JP2017510111A - Physical layer frame format for WLAN - Google Patents

Abstract

In a method for generating a physical layer (PHY) data unit that conforms to a first communication protocol for transmission over a communication channel, the first communication device generates a signal field and signals to the PHY preamble. Including a copy of the field and signal field and so that the first part of the PHY preamble can be decoded by a second communication device that is compliant with the second communication protocol but not the first communication protocol. Formatting the PHY preamble to generate a PHY preamble for the PHY data unit, including determining the duration of the PHY data unit based on the first portion of the PHY preamble. The first communication device generates a PHY data unit to include a PHY preamble and a PHY payload.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This disclosure is a continuation-in-part of US patent application Ser. No. 14 / 523,678 entitled “Range Extension Mode for WiFi” filed on Oct. 24, 2014. US Provisional Patent Application No. 61 / 895,591 entitled “Range Extension PHY” filed on May 25, US Provisional Patent Application No. “Range Extension PHY” filed on January 9, 2014 No. 61 / 925,332, US Provisional Patent Application No. 61 / 950,727 entitled “Range Extension PHY” filed on March 10, 2014, and “Range” filed on May 2, 2014. US Provisional Patent Application No. 61 entitled “Extension PHY” / 987,778, all of which are incorporated herein by reference in their entirety.

  Further, this disclosure is a US Provisional Patent Application No. 61 / 924,467 entitled “Physical Layer Frame Format for WLAN” filed on Jan. 7, 2014, filed on Jul. 29, 2014. US Provisional Patent Application No. 62 / 030,426 entitled “Physical Layer Frame Format for WLAN”; US Provisional Patent Application No. 62/030 entitled “Physical Layer Frame Format for WLAN” filed on August 7, 2014; No. 034,509, filed September 3, 2014, US Provisional Patent Application No. 62 / 045,363, filed September 17, 2014, entitled “Physical Layer Frame Format for WLAN” US Provisional Patent Application No. 62 / 051,537 entitled “Physical Layer Frame Format for WLAN” and US Provisional Patent Application entitled “Physical Layer Frame Format for WLAN” filed on Dec. 8, 2014 No. 62 / 089,032 is claimed and all these disclosures are hereby incorporated by reference in their entirety.

  The present disclosure relates generally to wireless communication networks, and more specifically to a physical layer (PHY) frame format that facilitates coexistence with legacy devices in wireless local area networks.

  Typically, when operating in infrastructure mode, a wireless local area network (WLAN) includes an access point (AP) and one or more client stations. WLAN has evolved rapidly over the past decade. With the development of WLAN standards such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11a, 802.11b, 802.11g and 802.11n standards, single user peak data throughput has been improved. For example, the IEEE 802.11b standard specifies a single user peak throughput of 11 megabits per second (Mbps), the IEEE 802.11a and 802.11g standards specify a single user peak throughput of 54 Mbps, and the IEEE 802.11n standard is 600 Mbps. The IEEE 802.11ac standard defines single user peak throughput in the gigabit per second (Gbps) range. Future standards will guarantee to provide greater throughput, such as throughput in the range of tens of Gbps.

  In one embodiment, the method generates a physical layer (PHY) data unit for transmission over a communication channel, the PHY data unit complying with a first communication protocol. The method comprises generating a PHY preamble for a PHY data unit at a first communication device, the step including generating a signal field to include a signal field and a duplicate of the signal field in the PHY preamble; The PHY preamble is formatted such that the first portion of the PHY preamble can be decoded by a second communication device that conforms to the communication protocol 2 but does not conform to the first communication protocol. Determining the duration of the PHY data unit based on the portion. The method also includes generating a PHY data unit to include a PHY preamble and a PHY payload at the first communication device.

  In various other embodiments, the method further includes one of two or more of the following features, or any suitable combination.

  The signal field is a legacy signal field that can be decoded by the second communication device, the legacy signal field is included in the first part of the PHY preamble, and the legacy signal field contains information indicating the duration of the PHY data unit. Including.

  Generating the PHY preamble for the PHY data unit further includes generating an additional signal field that conforms to the second communication protocol and including the additional signal field in the second portion of the PHY preamble.

  The second part of the PHY preamble is not decodable by the second communication device.

  Generating the PHY preamble for the PHY data unit further includes including a further signal field replica in the second portion of the PHY preamble.

  Generating the PHY preamble for the PHY data unit further includes including a further signal field replica in the second portion of the PHY preamble.

  The signal field is a first signal field, and generating the PHY preamble for the PHY data unit includes generating a second signal field decodable by the second communication device, and a first PHY preamble first. The method further includes including a second signal field in the portion and including a first signal field in the second portion of the PHY preamble, wherein the second signal field is information indicating a duration of the PHY data unit. including.

  The second part of the PHY preamble is not decodable by the second communication device.

  A PHY preamble for the PHY data unit is generated to include a respective first guard interval between a plurality of orthogonal frequency division (OFDM) symbols in a first portion of the PHY preamble, the method comprising: Generating a PHY payload to include a respective second guard interval between a plurality of OFDM symbols in the PHY payload, wherein each second guard interval is greater than each first guard interval. Also has a long duration.

  The PHY preamble for the PHY data unit is generated to include a respective second guard interval between the multiple OFDM symbols in the second portion of the PHY preamble.

  In another embodiment, the first communication device is compliant with the second communication protocol, generating a signal field, including a signal field and a duplicate of the signal field in a physical layer (PHY) preamble, The PHY preamble is formatted so that the first part of the PHY preamble can be decoded by a second communication device that does not conform to the first communication protocol, and the PHY data unit is based on the first part of the PHY preamble. A network interface device having one or more integrated circuits configured to generate a PHY preamble for a PHY data unit that conforms to a first communication protocol, including determining a duration. The one or more integrated circuits are also configured to generate a PHY data unit that includes a PHY preamble and a PHY payload.

  In various other embodiments, the first communication device further includes one of two or more of the following features, or any suitable combination.

  The signal field is a legacy signal field that is decodable by the second communication device, and the one or more integrated circuits are configured to include the legacy signal field in the first portion of the PHY preamble, Contains information indicating the duration of the PHY data unit.

  The one or more integrated circuits are configured to generate a further signal field that conforms to the second communication protocol and to include the further signal field in the second portion of the PHY preamble.

  The second part of the PHY preamble is not decodable by the second communication device.

  The one or more integrated circuits are configured to include additional signal field replicas in the second portion of the PHY preamble.

  The one or more integrated circuits are configured to include additional signal field replicas in the second portion of the PHY preamble.

  The signal field is a first signal field, and the one or more integrated circuits generate a second signal field that can be decoded by the second communication device, and the second signal in the first portion of the PHY preamble. The field is configured to include a first signal field in the second portion of the PHY preamble, the second signal field including information indicating a duration of the PHY data unit.

  The second part of the PHY preamble is not decodable by the second communication device.

  One or more integrated circuits generate a PHY preamble for a PHY data unit that includes a respective first guard interval between a plurality of orthogonal frequency division (OFDM) symbols in a first portion of the PHY preamble, and in the PHY payload It is configured to generate a PHY payload that includes a respective second guard interval between a plurality of OFDM symbols, each second guard interval having a longer duration than the first guard interval.

  The one or more integrated circuits are configured to generate the PHY preamble to include a respective second guard interval between the plurality of OFDM symbols in the second portion of the PHY preamble.

1 is a block diagram of an exemplary wireless local area network (WLAN), according to one embodiment. FIG.

It is a figure of the data unit format of a prior art. It is a figure of the data unit format of a prior art.

FIG. 4 is a diagram of another prior art data unit format.

FIG. 4 is a diagram of another prior art data unit format.

FIG. 4 is a diagram of another prior art data unit format.

FIG. 4 is a group of modulation diagrams used to modulate a plurality of symbols in a prior art data unit.

6 is a group of multiple modulation diagrams used to modulate multiple symbols in an exemplary data unit, according to one embodiment.

FIG. 3 is a diagram of an orthogonal frequency division multiplexing (OFDM) data unit, according to one embodiment.

7B is a group of multiple modulation diagrams used to modulate symbols in the data unit illustrated in FIG. 7A, according to one embodiment.

FIG. 3 is a block diagram of an OFDM symbol according to one embodiment.

FIG. 4 illustrates an exemplary data unit in which a standard encoding scheme is used for the preamble of the data unit, according to one embodiment.

FIG. 4 illustrates an exemplary data unit in which a standard encoding scheme is used for only a portion of the preamble of the data unit, according to one embodiment.

FIG. 4 illustrates an exemplary data unit in which tone spacing adjustment is used in combination with block coding, according to one embodiment.

FIG. 6 illustrates an exemplary data unit in which tone spacing adjustment is used in combination with block coding, according to another embodiment.

FIG. 6 illustrates a standard mode data unit according to one embodiment.

FIG. 6 illustrates a distance extension mode data unit, according to one embodiment.

FIG. 3 illustrates two possible formats for a long training field, respectively, according to two exemplary embodiments. FIG. 3 illustrates two possible formats for a long training field, respectively, according to two exemplary embodiments.

FIG. 11B illustrates a non-legacy signal field of the standard mode data unit of FIG. 11A, according to one embodiment.

FIG. 12 is a diagram illustrating a non-legacy signal field of the distance extension mode data unit of FIG. 11B, according to one embodiment.

FIG. 6 is a block diagram illustrating a distance extension mode data unit, according to one embodiment.

FIG. 14B illustrates a legacy signal field of the distance extension mode data unit of FIG. 14A, according to one embodiment.

FIG. 14B is a diagram illustrating a Fast Fourier Transform (FFT) window for a legacy signal field in the legacy receiving device of FIG. 14B, according to one embodiment.

FIG. 3 is a block diagram illustrating the format of a non-legacy signal field, according to one embodiment.

2 is a block diagram illustrating an exemplary PHY processing unit that generates multiple standard mode data units using a standard encoding scheme, according to one embodiment. FIG.

2 is a block diagram of an exemplary PHY processing unit that generates a plurality of distance extension mode data units using a distance extension encoding scheme, according to one embodiment. FIG.

FIG. 6 is a block diagram of an exemplary PHY processing unit that generates multiple distance extension mode data units according to another embodiment.

FIG. 4 is a block diagram of an exemplary PHY processing unit that generates a plurality of distance extension mode data units using a distance extension encoding scheme, according to another embodiment.

FIG. 6 is a block diagram of an exemplary PHY processing unit that generates multiple distance extension mode data units according to another embodiment.

FIG. 6 is a block diagram of an exemplary PHY processing unit that generates multiple distance extension mode data units according to another embodiment.

FIG. 6 is a block diagram of an exemplary PHY processing unit that generates multiple distance extension mode data units according to another embodiment.

FIG. 4 is a diagram illustrating repetition of multiple OFDM symbols in a preamble of a distance extension mode data unit, according to one embodiment.

FIG. 4 is a diagram illustrating repetition of multiple OFDM symbols in a preamble of a distance extension mode data unit, according to one embodiment.

FIG. 3 illustrates a time domain repetition scheme for multiple OFDM symbols, according to one embodiment.

FIG. 6 illustrates a repetition scheme for multiple OFDM symbols according to another embodiment.

FIG. 3 is a flow diagram of an exemplary method for generating a data unit, according to one embodiment.

FIG. 4 is a diagram of an entire 20 MHz bandwidth with repetition of a distance extension data unit having a 10 MHz subband, according to one embodiment.

FIG. 4 is a diagram of the entire 40 MHz bandwidth with repetition of a distance extension data unit having a 10 MHz subband, according to one embodiment.

FIG. 3 is an exemplary tone plan for a 32 point FFT mode, according to one embodiment.

FIG. 6 is a diagram of an example data unit in which distance extension mode is used for the preamble of the data unit, according to one embodiment.

FIG. 6 is a block diagram of an exemplary PHY processing unit that generates multiple distance extension mode data units according to another embodiment.

FIG. 3 is an exemplary 20 MHz full bandwidth diagram with 1/2 tone spacing, according to one embodiment.

FIG. 3 is an exemplary 20 MHz full bandwidth diagram with 1/2 tone spacing, according to one embodiment.

FIG. 6 is a diagram of a non-legacy tone plan in distance extension mode with a size 64 FFT and a 1/2 tone spacing, according to one embodiment.

FIG. 4 is a diagram of a non-legacy tone plan in distance extension mode with a size 128 FFT and a 1/2 tone spacing, according to one embodiment.

FIG. 6 illustrates a distance extension mode non-legacy tone plan with a size 256 FFT and a 1/2 tone spacing, according to one embodiment.

FIG. 3 is a flow diagram of an exemplary method for generating a data unit, according to one embodiment.

FIG. 6 is a flow diagram of an exemplary method for generating a data unit, according to another embodiment.

FIG. 3 is a diagram comparing a portion of an exemplary PHY preamble that conforms to a first communication protocol with a portion of a preamble that conforms to a legacy protocol, according to one embodiment.

FIG. 5 is a diagram comparing a portion of another exemplary PHY preamble that conforms to a first communication protocol with a portion of a preamble that conforms to a legacy protocol, according to another embodiment.

FIG. 5 is a diagram comparing a portion of another exemplary PHY preamble that conforms to a first communication protocol with a portion of a preamble that conforms to a legacy protocol, according to another embodiment.

FIG. 5 is a diagram comparing a portion of another exemplary PHY preamble that conforms to a first communication protocol with a portion of a preamble that conforms to a legacy protocol, according to another embodiment.

FIG. 5 is a diagram comparing a portion of another exemplary PHY preamble that conforms to a first communication protocol with a portion of a preamble that conforms to a legacy protocol, according to another embodiment.

FIG. 5 is a diagram comparing a portion of another exemplary PHY preamble that conforms to a first communication protocol with a portion of a preamble that conforms to a legacy protocol, according to another embodiment.

FIG. 5 is a diagram comparing a portion of another exemplary PHY preamble that conforms to a first communication protocol with a portion of a preamble that conforms to a legacy protocol, according to another embodiment.

FIG. 5 is a diagram comparing a portion of another exemplary PHY preamble that conforms to a first communication protocol with a portion of a preamble that conforms to a legacy protocol, according to another embodiment.

FIG. 5 is a diagram comparing a portion of another exemplary PHY preamble that conforms to a first communication protocol with a portion of a preamble that conforms to a legacy protocol, according to another embodiment.

FIG. 38 illustrates an example of an auto detect symbol used with the example PHY preamble of FIG. 37, according to various embodiments. FIG. 38 illustrates an example of an auto detect symbol used with the example PHY preamble of FIG. 37, according to various embodiments. FIG. 38 illustrates an example of an auto detect symbol used with the example PHY preamble of FIG. 37, according to various embodiments. FIG. 38 illustrates an example of an auto detect symbol used with the example PHY preamble of FIG. 37, according to various embodiments.

FIG. 5 is a diagram comparing a portion of another exemplary PHY preamble that conforms to a first communication protocol with a portion of a preamble that conforms to a legacy protocol, according to another embodiment.

FIG. 4 is a diagram of a portion of another example PHY preamble that conforms to a first communication protocol, according to another embodiment.

FIG. 4 is a diagram of a portion of another example PHY preamble that conforms to a first communication protocol, according to another embodiment.

FIG. 4 is a diagram of a portion of another example PHY preamble that conforms to the distance extension mode of the first communication protocol, and another example PHY preamble that conforms to the standard mode of the first communication protocol, according to one embodiment. It is the figure which compared a part with preamble part based on a legacy protocol.

FIG. 4 is a diagram of a portion of another example PHY preamble that conforms to the distance extension mode of the first communication protocol, and another example PHY preamble that conforms to the standard mode of the first communication protocol, according to one embodiment. Some figures are compared with some preambles that conform to the legacy protocol.

Part of another exemplary PHY preamble that conforms to the distance extension mode of the first communication protocol, and part of another example PHY preamble that conforms to the standard mode of the first communication protocol, according to one embodiment. Is a diagram comparing a part of a preamble that conforms to a legacy protocol.

  In embodiments described below, a wireless network device, such as a wireless local area network (WLAN) access point (AP), transmits multiple data streams to one or more client stations. The AP is configured to operate with a plurality of client stations in compliance with at least the first communication protocol. The first communication protocol may be referred to herein as a “high efficiency Wi-Fi”, “HEW” communication protocol, or 802.11ax communication protocol. In some embodiments, different client stations near the AP are in the same frequency band as the HEW communication protocol, but generally comply with one or more other communication protocols that specify operation with lower data throughput. Configured to work. Lower data throughput communication protocols (eg, IEEE 802.11a, IEEE 802.11n, and / or IEEE 802.11ac) are collectively referred to herein as “legacy” communication protocols. In at least some embodiments, legacy communication protocols are commonly used in indoor communication channels, and HEW communication protocols are at least sometimes reduced in outdoor communication, distance extension communication, or signal to noise ratio (SNR) of transmitted signals. Used in area communications.

  According to one embodiment, the multiple symbols transmitted by the AP are generated by a distance extension coding scheme that provides increased redundancy of symbols or information bits encoded within the symbols. Redundancy increases the likelihood that symbols will be successfully decoded, especially by devices that receive multiple symbols from the AP in areas of reduced SNR. In general, the amount of redundancy required to mitigate the reduced SNR depends on delay channel spread (eg, for outdoor communication channels), symbols and / or other signals that interfere with other factors. To do. In one embodiment, the HEW communication protocol defines a standard mode and a distance extension mode. In one embodiment, standard mode is generally used with multiple communication channels characterized by shorter channel delay spread (eg, indoor communication channel) or generally higher SNR values, while distance extension mode is generally relatively Used with communication channels characterized by long channel delay spread (eg, outdoor communication channels) or generally lower SNR values. In one embodiment, the standard encoding scheme is used in standard mode and the distance extension encoding scheme is used in distance extension mode.

  In one embodiment, the data unit transmitted by the AP includes a preamble and a data portion that is used, at least in part, to signal various parameters used to transmit the data portion to the receiving device. It is done. In various embodiments, the data unit preamble is used to signal a receiving device a specific encoding scheme that uses at least the data portion of the data unit. In some embodiments, the same preamble format as in distance extension mode is used in standard mode. In one such embodiment, the preamble includes an indication set that indicates whether a standard encoding scheme or a distance extension encoding scheme is used for at least the data portion of the data unit. In some embodiments, the standard encoding scheme or distance extension encoding scheme shown is used for at least a portion of the data unit preamble in addition to the data portion of the data unit. In one embodiment, the receiving device determines a particular encoding scheme that is being used based on an indication in the preamble of the data unit, and then uses the particular encoding scheme to use the appropriate remaining portion of the data unit ( For example, a data part or a preamble and a part of the data part) are decoded.

  In another embodiment, the preamble used in distance extension mode is formatted differently than the preamble used in standard mode. For example, the preamble used in the distance extension mode is formatted such that the receiving device can automatically detect (eg, before decoding) that the data unit corresponds to the distance extension mode. In one embodiment, if the receiving device detects that the data unit corresponds to a distance extension mode, the receiving device decodes the data portion of the data unit using a distance extension encoding scheme, and at least some embodiments In step 1, at least a part of the preamble and a data part of the data unit are decoded. On the other hand, if the receiving device detects that the data unit does not support the distance extension mode, the receiving device assumes in one embodiment that the data unit corresponds to the standard mode. Next, in one embodiment, the receiving device decodes at least the data portion of the data unit using a standard encoding scheme.

  In addition, in at least some embodiments, the preamble of the standard mode and / or extended distance mode data unit is a data unit such as the duration of the data unit by a client station operating according to a legacy protocol rather than a HEW communication protocol. Specific information and / or data unit is formatted so that it can be determined that the data unit is not compliant with the legacy protocol. Furthermore, the data unit preamble is, in one embodiment, formatted by a client station operating according to the HEW protocol that the data unit conforms to the HEW communication protocol, and the data unit is formatted according to a standard mode or a distance extension mode. Formatted so that it can be determined. Similarly, a client station configured to operate in accordance with the HEW communication protocol also transmits a plurality of data units as described above in one embodiment.

  In at least some embodiments, for example, a client station that conforms to a plurality of different communication protocols, and / or a plurality of client stations that are configured to operate with a plurality of WLANs that operate according to a plurality of different communication protocols. Formatted data units such as those described above with a AP are useful. Continuing with the above example, a communication device configured to operate in accordance with both the HEW communication protocol (including the standard mode and distance extension mode) and the legacy communication protocol is such that a given data unit is a legacy communication protocol. Rather, it can be determined that the data unit is formatted according to the HEW communication protocol, and it can be further determined that the data unit is formatted according to the distance extension mode instead of the standard mode. Similarly, a communication device configured to operate in compliance with a legacy communication protocol rather than a HEW communication protocol may determine that the data unit is not formatted according to the legacy communication protocol and / or Can be determined.

  FIG. 1 is a block diagram of an exemplary wireless local area network (WLAN) 10 according to one embodiment. The AP 14 includes a host processor 15 coupled to the network interface 16. The network interface 16 includes a medium access control (MAC) processing unit 18 and a physical layer (PHY) processing unit 20. The PHY processing unit 20 includes a plurality of transceivers 21 that are coupled to a plurality of antennas 24. Although three transceivers 21 and three antennas 24 are illustrated in FIG. 1, in other embodiments, the AP 14 may have other suitable numbers (eg, 1, 2, 4, 5, etc.) of transceivers 21 and An antenna 24 is included. In one embodiment, the MAC processing unit 18 and the PHY processing unit 20 comply with a first communication protocol (eg, HEW communication protocol) that includes at least a first mode and a second mode of the first communication protocol. Configured to work. In some embodiments, the first mode may be a distance extension encoding scheme (eg, block encoding, bit-wise replication, or symbol replication), a signal modulation scheme (eg, phase shift keying or quadrature amplitude modulation), or It corresponds to distance extension mode using both distance extension coding scheme and signal modulation scheme. The distance extension mode is configured to increase distance and / or reduce signal to noise (SNR) ratio compared to a second mode (eg, a standard mode using a standard coding scheme) at this SNR. A successful decoding of the PHY data unit that conforms to the distance extension mode is performed. In various embodiments, the distance extension mode reduces the data rate of transmission compared to the standard mode and achieves successful decoding with increased distance and / or reduced SNR ratio. In another embodiment, the MAC processing unit 18 and the PHY processing unit 20 are configured to operate in accordance with a second communication protocol (eg, the IEEE 802.11ac standard). In yet another embodiment, the MAC processing unit 18 and the PHY processing unit 20 may include a second communication protocol, a third communication protocol, and / or a fourth communication protocol (eg, IEEE 802.11a standard and / or IEEE 802). .11n standard).

  The WLAN 10 includes a plurality of client stations 25. Although four client stations 25 are illustrated in FIG. 1, in various scenarios and embodiments, the WLAN 10 includes other suitable numbers (eg, 1, 2, 3, 5, 6, etc.) of client stations 25. . At least one of the plurality of client stations 25 (for example, the client station 25-1) is configured to operate according to at least the first communication protocol. In some embodiments, at least one of the plurality of client stations 25 is not configured to operate in accordance with the first communication protocol, but the second communication protocol, the third communication protocol, and / or Or configured to operate in accordance with at least one of the fourth communication protocols (referred to herein as a “legacy client station”).

  Client station 25-1 includes a host processor 26 coupled to network interface 27. The network interface 27 includes a MAC processing unit 28 and a PHY processing unit 29. The PHY processing unit 29 includes a plurality of transceivers 30 that are coupled to a plurality of antennas 34. Although three transceivers 30 and three antennas 34 are illustrated in FIG. 1, in other embodiments, the client station 25-1 may have other suitable numbers (eg, 1, 2, 4, 5, etc.). Transceiver 30 and antenna 34.

  According to one embodiment, client station 25-4 is a legacy client station. That is, it is not possible for the client station 25-4 to receive and completely decode a data unit transmitted by the AP 14 or another client station 25 in accordance with the first communication protocol. Similarly, according to one embodiment, it is not possible for legacy client station 25-4 to transmit multiple data units in accordance with the first communication protocol. On the other hand, the legacy client station 25-4 can receive, completely decode and transmit the data unit in accordance with the second communication protocol, the third communication protocol, and / or the fourth communication protocol. It becomes.

  In one embodiment, one or both of the client stations 25-2 and 25-3 have the same or similar structure as the client station 25-1. In one embodiment, the client station 25-4 has a structure similar to the client station 25-1. In these embodiments, a plurality of client stations 25 having the same or similar structure as the client station 25-1 have the same or different numbers of transceivers and antennas. For example, according to one embodiment, client station 25-2 has only two transceivers and two antennas (not shown).

  In various embodiments, the PHY processing unit 20 of the AP 14 is configured to generate a plurality of data units that conform to a first communication protocol and have a plurality of formats described herein. The transceiver 21 is configured to transmit a plurality of generated data units via the antenna 24. Similarly, the transceiver 21 is configured to receive a plurality of data units via the antenna 24. According to various embodiments, the PHY processing unit 20 of the AP 14 processes a plurality of received data units that conform to a first communication protocol and have a plurality of formats described herein below, A plurality of such data units are configured to determine that they are compliant with the first communication protocol.

  In various embodiments, the PHY processing unit 29 of the client device 25-1 is configured to generate a plurality of data units that conform to the first communication protocol and have a plurality of formats described herein. The The transceiver 30 is configured to transmit a plurality of generated data units via the antenna 34. Similarly, transceiver 30 is configured to receive a plurality of data units via antenna 34. According to various embodiments, the PHY processing unit 29 of the client device 25-1 is compliant with the first communication protocol and has a plurality of received data units having a plurality of formats as described herein below. And determining that a plurality of such data units are compliant with the first communication protocol.

  FIG. 2A is a diagram of a prior art OFDM data unit 200 configured for AP 14 to transmit to legacy client station 25-4 via orthogonal frequency division multiplexing (OFDM) modulation, according to one embodiment. In one embodiment, legacy client station 25-4 is also configured to transmit data unit 200 to AP. The data unit 200 conforms to the IEEE 802.11a standard and occupies a 20 megahertz (MHz) band. The data unit 200 includes a legacy short training field (L-STF) 202 generally used for packet detection, initial synchronization and automatic gain control, etc., and a legacy long training field (L-LTF) 204 generally used for channel estimation and fine synchronization. Including a preamble. The data unit 200 also includes a legacy signal field (L-SIG) 206, which is a specific physical layer (PHY) for the data unit 200, such as, for example, the modulation type and coding rate used to transmit the data unit. Used to carry parameters. Data unit 200 also includes a data portion 208. FIG. 2B is a diagram of an example data portion 208 (low density parity check is not encoded), where the example data portion 208 is service field, scrambled physical layer service data unit (PSDU) if necessary. , Tail bits, and padding bits. Data unit 200 is designed for transmission over a single spatial or spatio-temporal stream in a single input single output (SISO) channel configuration.

  FIG. 3 is a diagram of a prior art OFDM data unit 300 configured for an AP 14 to transmit to a legacy client station 25-4 via orthogonal frequency division multiplexing (OFDM) modulation, according to one embodiment. In one embodiment, legacy client station 25-4 is also configured to transmit data unit 300 to AP. The data unit 300 is compliant with the IEEE 802.11n standard, occupies a 20 MHz band, and is in a mixed mode situation, i.e., one or more client stations where the WLAN is compliant with the IEEE 802.11a standard but is not compliant with the IEEE 802.11n standard. Designed for cases involving. The data unit 300 includes an L-STF 302, an L-LTF 304, an L-SIG 306, a high throughput signal field (HT-SIG) 308, a high throughput short training field (HT-STF) 310, and M data high throughput long training fields. A preamble with (HT-LTF) 312. In general, M is an integer determined by the number of spatial streams used to transmit a data unit 300 in a multiple input multiple output (MIMO) channel configuration. Specifically, in accordance with the IEEE 802.11n standard, the data unit 300 includes two HT-LTFs 312 when the data unit 300 is transmitted using two spatial streams, and three data units 300 or When transmitted using four spatial streams, four HT-LTFs 312 are included. An indication of the particular number of spatial streams used is included in the HT-SIG field 308. Data unit 300 also includes a data portion 314.

  FIG. 4 is a diagram of a prior art OFDM data unit 400 configured for an AP 14 to transmit to a legacy client station 25-4 via orthogonal frequency division multiplexing (OFDM) modulation, according to one embodiment. In one embodiment, legacy client station 25-4 is also configured to transmit data unit 400 to AP. The data unit 400 is compliant with the IEEE 802.11n standard, occupies a 20 MHz band, is in a “green field” situation, ie, does not include any client station whose WLAN is compliant with the IEEE 802.11a standard, and is compliant with the IEEE 802.11n standard. Designed for cases involving only client stations. Data unit 400 includes a high-throughput green field short training field (HT-GF-STF) 402, a first high-throughput long training field (HT-LTF1) 404, HT-SIG 406, and a preamble having M pieces of data HT-LTF 408. including. In general, M is an integer corresponding to the number of spatial streams used to transmit a data unit 400 in a multiple-input multiple-output (MIMO) channel configuration. Data unit 400 also includes a data portion 410.

  FIG. 5 is a diagram of a prior art OFDM data unit 500 that is configured for an AP 14 to transmit to a legacy client station 25-4 via orthogonal frequency division multiplexing (OFDM) modulation, according to one embodiment. In one embodiment, legacy client station 25-4 is also configured to transmit data unit 500 to AP. Data unit 500 conforms to the IEEE 802.11ac standard and is designed for “mixed field” situations. Data unit 500 occupies a 20 MHz bandwidth. In other embodiments or scenarios, data units similar to data unit 500 occupy different bandwidths, such as 40 MHz, 80 MHz, or 160 MHz bandwidths. Data unit 500 includes L-STF 502, L-LTF 504, L-SIG 506, first very high throughput signal field (VHT-SIGA1) 508-1 and second very high throughput signal field (VHT-SIGA2) 508-2. Two first very high throughput signal fields (VHT-SIGA) 508, very high throughput short training field (VHT-STF) 510, M very high throughput long training fields (VHT-LTF) 512, and It includes a preamble with two very high throughput signal fields (VHT-SIG-B) 514. M is an integer. Data unit 500 also includes a data portion 516.

  6A is a set of diagrams illustrating the modulation of the L-SIG, HT-SIG1 and HT-SIG2 fields of the data unit 300 in FIG. 3, as defined by the IEEE 802.11n standard. The L-SIG field is modulated by binary phase shift keying (BPSK), and the HT-SIG1 and HT-SIG2 fields are modulated by BPSK but on the orthogonal axis (Q-BPSK). In other words, the modulation of the HT-SIG1 and HT-SIG2 fields is rotated by 90 ° compared to the modulation of the L-SIG field.

  6B is a set of diagrams illustrating the modulation of the L-SIG, VHT-SIGA1 and VHT-SIGA2 fields of the data unit 500 in FIG. 5 as defined by the IEEE 802.11ac standard. Unlike the HT-SIG1 field in FIG. 6A, the VHT-SIGA1 field is modulated by the same BPSK as the modulation of the L-SIG field. On the other hand, the VHT-SIGA2 field is rotated 90 ° compared to the modulation of the L-SIG field.

  FIG. 7A is a diagram of an OFDM data unit 700 configured for AP 14 to transmit to client station 25-1 via orthogonal frequency division multiplexing (OFDM) modulation, according to one embodiment. In one embodiment, the client station 25-1 is also configured to transmit the data unit 700 to the AP 14. The data unit 700 conforms to the first communication protocol and occupies a 20 MHz bandwidth. In other embodiments, like the data unit 700, the plurality of data units compliant with the first communication protocol may be, for example, 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz, or some other suitable bandwidth, etc. May occupy other suitable bandwidth. Data unit 700 is suitable in a “mixed mode” situation, ie, when WLAN 10 includes a client station (eg, legacy client station 25-4) that conforms to the legacy communication protocol but does not conform to the first communication protocol. . In some embodiments, the data unit 700 is also used in a number of other situations.

  In one embodiment, the data unit 700 includes an L-STF 702, an L-LTF 704, an L-SIG 706, a first HEW signal field (HEW-SIGA1) 708-1, and a second HEW signal field (HEW-SIGA2) 708-. Two first HEW signal fields (HEW-SIGA) 708, two HEW short training fields (HEW-STF) 710, M HEW long training fields (HEW-LTF) 712, and a third HEW signal field Including a preamble 701 with (HEW-SIGB) 714, where M is an integer. Each of L-STF 702, L-LTF 704, L-SIG 706, HEW-SIGA 708, HEW-STF 710, M HEW-LTF 712, and HEW-SIGB 714 includes an integer of one or more OFDM symbols. For example, in one embodiment, HEW-SIGA 708 includes two OFDM symbols, the HEW-SIGA1 708-1 field includes a first OFDM symbol, and HEW-SIGA2 includes a second OFDM symbol. For example, in another embodiment, preamble 701 includes a third HEW signal field (HEW-SIGA3, not shown), HEW-SIGA 708 includes three OFDM symbols, and HEW-SIGA1 708-1 field includes The first OFDM symbol is included, HEW-SIGA2 includes the second OFDM symbol, and HEW-SIGA3 includes the third OFDM symbol. In at least some examples, the plurality of HEW-SIGA 708 are collectively referred to as one HEW signal field (HEW-SIGA) 708. In some embodiments, the data unit 700 also includes a data portion 716. In other embodiments, the data unit 700 omits the data portion 716.

  In the embodiment of FIG. 7A, data unit 700 includes L-STF 702, L-LTF 704, L-SIG 706, and one of each of a plurality of HEW-SIGA1 708s. In other embodiments where an OFDM data unit similar to data unit 700 occupies a cumulative bandwidth other than 20 MHz, L-STF 702, L-LTF 704, L-SIG 706, and each of the plurality of HEW-SIGA1 708 are one Iterate over a corresponding number of 20 MHz subbands of the full bandwidth of the data unit of the embodiment. For example, in one embodiment, an OFDM data unit occupies an 80 MHz bandwidth and thus includes four of each of L-STF 702, L-LTF 704, L-SIG 706, and multiple HEW-SIGA1 708 in one embodiment. In some embodiments, the modulation of different 20 MHz subband signals is rotated at different angles. For example, in one embodiment, the first subband rotates 0 °, the second subband rotates 90 °, the third subband rotates 180 °, and the fourth subband rotates 270 °. In other embodiments, different suitable rotations are used. In at least some embodiments, the plurality of different phases of the 20 MHz subband signal results in a reduction in OFDM symbol peak-to-average power ratio (PAPR) in data unit 700. In one embodiment, if the data unit conforming to the first communication protocol is an OFDM data unit occupying a cumulative bandwidth such as 20 MHz, 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz, etc., HEW-STF, multiple HEW- The LTF, HEW-SIGB and HEW data portions occupy the entire corresponding bandwidth of the data unit.

  7B is a set of diagrams illustrating modulation of L-SIG 706, HEW-SIGA1 708-1, and HEW-SIGA2 708-2 of data unit 700 in FIG. 7A, according to one embodiment. In this embodiment, the L-SIG 706, HEW-SIGA1 708-1 and HEW-SIGA2 708-2 fields are defined in the IEEE 802.11ac standard and have the same modulation as the corresponding field modulation illustrated in FIG. 6B. . Accordingly, the HEW-SIGA1 field is modulated in the same manner as the L-SIG field. On the other hand, the HEW-SIGA2 field is rotated 90 ° compared to the modulation of the L-SIG field. In some embodiments having a third HEW-SIGA3 field, the HEW-SIGA2 field is modulated similarly to the L-SIG field and the HEW-SIGA1 field, but the HEW-SIGA3 field is an L-SIG field, Compared with the modulation of HEW-SIGA1 field and HEW-SIGA2 field, it is rotated by 90 °.

  In one embodiment, modulation of the L-SIG 706, HEW-SIGA1 708-1, and HEW-SIGA2 708-2 fields of the data unit 700 is a data unit that conforms to the IEEE 802.11ac standard (eg, the data unit 500 of FIG. 5). A plurality of legacy client stations configured to operate in accordance with the IEEE 802.11a standard and / or the IEEE 802.11n standard may support data units in at least some conditions. Assuming that 700 conforms to the IEEE 802.11ac standard, the data unit 700 is processed accordingly. For example, a client station conforming to the IEEE 802.11a standard understands the legacy IEEE 802.11a standard portion of the preamble of the data unit 700 and follows the data unit duration (or data unit duration) according to the duration indicated in L-SIG 706. ) Is set. For example, according to one embodiment, legacy client station 25-4 calculates a duration for the data unit based on the rate and length (eg, number of bytes) indicated in L-SIG field 706. In one embodiment, the rate and length in L-SIG field 706 is based on the actual duration of data unit 700 based on the rate and length by a client station configured to operate in accordance with a legacy communication protocol. Is set to calculate a packet duration (T) that corresponds to or at least close to. In one embodiment, for example, the rate is set to indicate the lowest rate specified by the IEEE 802.11a standard (ie, 6 Mbps), and the length is the packet duration calculated using the lowest rate in data unit 700. Is set to a value calculated to be at least close to the actual duration of.

  In one embodiment, when a legacy client station that conforms to the IEEE 802.11a standard receives the data unit 700, it calculates the packet duration of the data unit 700 using, for example, the rate and length fields of the L-SIG field 706. , In one embodiment, wait until the end of the calculated packet duration before performing a clear channel assessment (CCA). Thus, in this embodiment, the communication medium is protected from access by legacy client stations for at least the duration of data unit 700. In one embodiment, the legacy client station continues to decode the data unit 700, but an error check fails (eg, using a frame check sequence (FCS)) at the end of the data unit 700.

  Similarly, in one embodiment, when a legacy client station configured to operate in accordance with the IEEE 802.11n standard receives the data unit 700, the rate and length indicated in the L-SIG 706 of the data unit 700 are shown. Based on the above, the packet duration (T) of the data unit 700 is calculated. The legacy client station detects the modulation of the first HEW signal field (HEW-SIGA1) 708-1 (BPSK) and assumes that the data unit 700 is a legacy data unit conforming to the IEEE 802.11a standard. In one embodiment, the legacy client station continues to decode the data unit 700, but an error check fails at the end of the data unit (eg, using a frame check sequence (FCS)). In any case, in accordance with the IEEE 802.11n standard, the legacy client station, in one embodiment, waits until the calculated packet duration (T) expires before performing a clear channel evaluation (CCA). Thus, in the embedding, the communication medium is protected from access by legacy client stations during the duration of the data unit 700.

  In one embodiment, a legacy client station configured to operate in accordance with the IEEE 802.11ac standard rather than the first communication protocol receives the data unit 700 and is indicated in L-SIG 706 of the data unit 700. Calculate the packet duration (T) of the data unit 700 based on the rate and length. However, in one embodiment, the legacy client station cannot detect that the data unit 700 is not compliant with the IEEE 802.11ac standard based on the modulation of the data unit 700. In some embodiments, one or more HEW signal fields (eg, HEW-SIGA1 and / or HEW-SIGA2) of data unit 700 may cause errors to legacy client stations when intentionally decoding data unit 700. It is formatted to detect and thus stop (or “drop”) decoding of the data unit 700. In one embodiment, for example, the HEW-SIGA 708 of the data unit 700 is formatted to intentionally cause an error when the SIGA field is decoded by a legacy device according to the IEEE 802.11ac standard. Further, in an embodiment, in accordance with the IEEE 802.11ac standard, if an error is detected when decoding a VHT-SIGA field, the client station drops the data unit 700, eg, Clear Channel Evaluation (CCA) Wait until the calculated packet duration (T) calculated based on the rate and length indicated in L-SIG 706 of data unit 700 ends. Thus, in one embodiment, the communication medium is protected from access by legacy client stations during the duration of data unit 700.

  FIG. 8 is a diagram of an OFDM symbol 800 according to one embodiment. In one embodiment, data unit 700 in FIG. 7A includes an OFDM symbol, such as OFDM symbol 800. OFDM symbol 800 includes a guard interval (GI) portion 802 and an information portion 804. In one embodiment, the guard interval includes a cyclic prefix that repeats the last portion of the OFDM symbol. In one embodiment, guard interval portion 802 ensures OFDM symbol orthogonality at the receiving device (eg, client station 25-1), and OFDM symbol 800 is transmitted from the transmitting device (eg, AP 14) to the receiving device. It is used to minimize or eliminate intersymbol interference due to multipath propagation in the communication channel. In one embodiment, the length of the guard interval portion 802 is selected based on the worst case channel delay spread expected in the communication channel between the transmitting device and the receiving device. In one embodiment, for example, longer guard intervals are typically longer channels compared to shorter guard intervals selected for multiple indoor communication channels that are typically characterized by shorter channel delay spreads. Selected for multiple outdoor communication channels characterized by delay spread. In one embodiment, the length of the guard interval portion 802 is selected based on the interval of the tone from which the information portion 804 was generated (eg, the interval between multiple subcarrier frequencies of the full bandwidth in the data unit). For example, a longer guard interval is selected for a narrower tone interval (eg, 256 tones) compared to a shorter guard interval for a wider tone interval (eg, 64 tones).

  According to one embodiment, the guard interval portion 802 corresponds to a short guard interval, a normal guard interval, or a long guard interval depending on the transmission mode used. In one embodiment, an indoor communication channel, a communication channel with a relatively short channel delay spread, or a communication channel with a suitable high SNR ratio uses a short guard interval or a normal guard interval, and an outdoor communication channel, A long guard interval is used for communication channels with a long delay spread, or communication channels that do not have a suitable high SNR ratio. In one embodiment, when a HEW data unit (eg, HEW data unit 700) is transmitted in standard mode, a normal guard interval or a short guard interval is used for some or all OFDM symbols of the HEW data unit, and HEW If the data unit is transmitted in distance extension mode, a long guard interval is used for at least some OFDM symbols of the HEW data unit.

  In one embodiment, the short guard interval (SGI) has a length of 0.4 μs, the normal guard interval is 0.8 μs, and the long guard interval (LGI) has a length of 1.2 μs or 1.8 μs. Have. In one embodiment, the information portion 804 has a length of 3.2 μs. In other embodiments, the information portion 804 has an increased length corresponding to the interval of the tone from which the information portion 804 was generated. For example, the information portion 804 has a first length of 3.2 μs for a standard mode using a first tone spacing of 64 tones and a 6.55 for a 128 tone second tone spacing. Having a second length of 4 μs, the second tone spacing and the second length are both increased by an integer multiple of 2 compared to the first tone spacing and the first length. . In one embodiment, the remaining length of the information portion 804 is filled with a copy of the received time domain signal (eg, the information portion 804 includes two copies of the received time domain signal). In other embodiments, SGI, NGI, LGI, and / or other suitable lengths of information portion 804 are used. In some embodiments, the SGI has a length that is 50% of the length of the NGI, and the NGI has a length that is 50% of the length of the LGI. In other embodiments, the SGI has a length that is 75% or less of the length of the NGI, and the NGI has a length that is 75% or less of the length of the LGI. In other embodiments, the SGI has a length that is 50% or less of the length of the NGI, and the NGI has a length that is 50% or less of the LGI.

  In other embodiments, OFDM modulation with reduced tone spacing is pre-determined to indicate the same tone plan (eg, which OFDM tones are designated for data tones, pilot tones, and / or guard tones). Used in distance extension mode using a defined set of indices). For example, a standard mode for an OFDM data unit with a 20 MHz bandwidth results in 64 OFDM tones (eg, indices −32 to +31) using a 64 point discrete Fourier transform (DFT), and a distance extension mode is 20 MHz. A 128-point DFT is used for a single OFDM data unit, resulting in 128 OFDM tones (eg, index -64 to +63) with the same bandwidth. In this case, while using the same tone plan, the interval between tones in the distance extension mode OFDM symbol is reduced by half (1/2) compared to the standard mode OFDM symbol. As another example, the standard mode for an OFDM data unit with a 20 MHz bandwidth results in 64 OFDM tones using a 64-point discrete Fourier transform (DFT), while the distance extension mode is applied to a 20 MHz OFDM data unit. A 256 point DFT is used to provide 256 OFDM tones of the same bandwidth. In this case, the tone spacing in the distance extension mode OFDM symbol is reduced by a quarter (1/4) compared to the standard mode OFDM symbol. In several such embodiments, for example, a long GI duration of 1.6 μs is used. However, in one embodiment, the duration of the information portion in the distance extension mode OFDM symbol is increased (eg, from 3.2 μs to 6.4 μs), and the percentage of the duration of the GI portion relative to the total duration of the OFDM symbol is Still the same. Thus, in this case, in at least some embodiments, efficiency loss due to longer GI symbols is avoided. In various embodiments, the term “long guard interval” as used herein includes an increased duration of the guard interval and a reduced OFDM tone interval that substantially increases the duration of the guard interval.

  FIG. 9A is a diagram illustrating an example data unit 900 in which standard mode or distance extension mode is used for the preamble of the data unit, according to one embodiment. In general, the data unit 900 is the same as the data unit 700 of FIG. 7A and includes the same numbered elements as the data unit 700 of FIG. 7A. The HEW-SIGA field 708 (eg, HEW-SIGA1 708-1 or HEW-SIGA2 708-2) of the data unit 900 includes a coding indication (CI) 902. According to one embodiment, CI indication 902 is set to indicate one of (i) a standard mode using a standard encoding scheme, or (ii) a distance extension mode using a distance extension encoding scheme. . In one embodiment, the CI indication 902 includes one bit, the first value of the bit indicates a standard mode, and the second value of the bit indicates a distance extension mode. In some embodiments, the CI indication is combined with a modulation and coding scheme (MCS) indicator. For example, in one embodiment, the standard mode corresponds to an MCS value that is determined to be valid by a legacy receiver device (eg, conforming to the IEEE 802.11ac protocol), while the distance extension mode is (eg, IEEE 802.11ac). Corresponds to MCS values that are determined to be invalid (or not supported) by legacy receiver devices (which are not protocol compliant). In other embodiments, the CI indication 902 includes a plurality of bits indicating a plurality of standard mode MCS values and a plurality of distance extension mode MCS values. As illustrated in FIG. 9A, a standard encoding scheme is used for all OFDM symbols of the preamble of data unit 700, and in the illustrated embodiment, a standard encoding scheme or distance extension code indicated by CI indication 902. One of the encoding schemes is used for the OFDM symbol of the data portion 716.

  For example, in one embodiment, when a distance extension coding scheme is used for the OFDM symbol of the data portion 716, the distance and / or SNR for successfully decoding the PHY data unit is generally improved compared to the standard data unit. (Ie, successfully decoded at longer distances and / or lower SNR). In some embodiments, improved distance and / or SNR performance is not necessarily obtained for decoding the preamble 701, which is generated using a standard coding scheme. In some such embodiments, transmitting at least a portion of the preamble 701 using transmit power boost increases the decoding range of a portion of the preamble 701 compared to the transmit power used to transmit the data portion 716. To do. In some embodiments, a portion of the preamble 701 transmitted using transmit power boost is a legacy field such as L-STF 702, L-LTF 704, and L-SIG 708, and / or HEW-STF and HEW- Includes non-legacy fields such as LTF. In various embodiments, the transmit power boost is 3 dB, 6 dB, or other suitable value. In some embodiments, the transmit power boost is determined such that the “boosted” preamble 701 can be decoded with similar performance compared to the “not boosted” data portion 716 at the same location. In some embodiments, the increased length of L-STF 702, L-LTF 704, and / or L-SIG 706 is used in combination with transmit power boost. In other embodiments, the increased length of L-STF 702, L-LTF 704, and / or L-SIG 706 is used in place of transmit power boost.

  FIG. 9B is a diagram illustrating an example data unit 950 in which a distance extension encoding scheme is used for only a portion of the data unit preamble, according to one embodiment. In general, the data unit 950 includes a preamble 751 in which the encoding scheme indicated by the CI indication 902 is applied to a plurality of OFDM symbols that are part of the preamble 751 and a plurality of OFDM symbols that are the data portion 716. Is the same as the data unit 900 of FIG. 9A. Specifically, in the illustrated embodiment, a standard encoding scheme is used for the first portion 751-1 of the preamble 701, and one of the standard encoding scheme or the distance extension encoding scheme is CI As indicated by instruction 902, in addition to the multiple OFDM symbols of data portion 716, it is used for the multiple OFDM symbols of second portion 751-2 of preamble 751. Accordingly, in the illustrated embodiment, the encoding scheme indicated by CI indication 902 is applied at the beginning of the OFDM symbol corresponding to HEW-LTF 712-1, skipping the OFDM symbol corresponding to HEW-STF 710. In at least some embodiments, skipping HEW-STF 710 allows the device receiving data unit 950 to decode CI indication 902 and properly configure the receiver to receive CI before receiving the OFDM symbol. The encoding scheme indicated by instruction 902 is used to allow sufficient time to begin decoding of such multiple OFDM symbols.

  FIG. 10A is a diagram illustrating an exemplary data unit 1000 in which OFDM tone spacing adjustment is used in combination with bit and / or symbol repetition of a distance extension coding scheme, according to one embodiment. In general, data unit 1000 is small compared to the tone spacing used for the standard mode OFDM symbol of data unit 1000 when CI indication 902 indicates that a distance extension coding scheme is used in data unit 1000. 7A is the same as the data unit 900 of FIG. 7A, except that multiple OFDM symbols of the data portion 716 are generated using OFDM modulation with the toned spacing.

  FIG. 10B is a diagram illustrating an example data unit 1050 in which adjusting the spacing of OFDM tones is used in combination with bit and / or symbol repetition of a distance extension coding scheme, according to another embodiment. In general, data unit 1050 is small compared to the tone spacing used for the standard mode OFDM symbol of data unit 1050 when CI indication 902 indicates that distance extension coding scheme is used in data unit 1050. 9B is the same as the data unit 950 of FIG. 9B, except that OFDM modulation with the toned spacing is used to generate a plurality of OFDM symbols in the second portion 751-2 and a plurality of OFDM symbols in the data portion 716. . In the embodiment shown in FIG. 10A, the entire 20 MHz bandwidth is used, the normal tone spacing and guard interval in the first portion 751-1, and the tone spacing are reduced by two, the long guard interval and size 64. The FFT of is repeated twice over the entire bandwidth. In some embodiments, the transmit power boost is applied to the first portion 751-1. In other embodiments, other multiples such as 4x, 8x, or other suitable values are reduced tone spacing, increased guard interval, increased symbol duration, or increase in overall bandwidth. Used for one or more of the iterations.

  In some embodiments, a different preamble format is used for the distance extension mode data unit compared to the preamble used for the standard mode data unit. In multiple such embodiments, a device that receives a data unit may automatically detect whether the data unit is a standard mode data unit or a distance extension mode data unit based on the format of the data unit preamble. . FIG. 11A is a diagram illustrating a standard mode data unit 1100 according to one embodiment. The standard mode data unit 1100 includes a standard mode preamble 1101. In general, the standard mode preamble 1101 is the same as the preamble 701 of the data unit 700 of FIG. 7A. In one embodiment, the preamble 1101 includes a HEW-SIGA field 1108 that includes a first HEW-SIGA1 field 1108-1 and a second HEW-SIGA2 field 1108-2. In one embodiment, the HEW-SIGA field 1108 (eg, HEW-SIGA1 1108-1 or HEW-SIGA2 1108-2) of the preamble 1101 includes a CI indication 1102. In one embodiment, CI indication 1102 is set to indicate whether a distance extension encoding scheme or a standard encoding scheme is used for the OFDM symbol of data portion 716 in data unit 1100. In one embodiment, the CI indication 1102 includes one bit, the first value of the bit indicates a standard encoding scheme, and the second value of the bit indicates a distance extension encoding scheme. As described in more detail below, in one embodiment, a device that receives data unit 1100 detects, based on the format of preamble 1101, that preamble 1101 is a standard mode preamble rather than an extended mode preamble. Can do. In one embodiment, upon detecting that the preamble 1101 is a standard mode preamble, the receiving device uses a distance extension coding scheme for the plurality of OFDM symbols in the data portion 716 based on the CI indication 1102 or It is determined whether a standard encoding scheme is used and the data portion 716 is decoded accordingly. In some embodiments, when the CI indication 1102 indicates that a distance extension coding scheme is being used, some OFDM symbols (eg, HEW-LTF and HEW-SIGB) and data portions of the preamble 1101 716 OFDM symbols are generated using OFDM modulation with a tone spacing that is small compared to the tone spacing used for the standard mode OFDM symbols in data unit 1050.

  FIG. 11B is a diagram illustrating a distance extension mode data unit 1150, according to one embodiment. The distance extension mode data unit 1150 includes a distance extension mode preamble 1151. In general, the data unit 1150 is similar to the data unit 1100 of FIG. 11A, except that the preamble 1151 of the data unit 1150 is formatted differently than the preamble 1101 of the data unit 1100. In one embodiment, the preamble 1151 is formatted such that a receiving device operating according to the HEW communication protocol can determine that the preamble 1151 is not a standard mode preamble but a distance extension mode preamble. In one embodiment, distance extension mode preamble 1151 includes L-STF 702, L-LTF 704, and L-SIG 706, and one or more first HEW signal fields (HEW-SIGA) 1152. In one embodiment, preamble 1150 further includes one or more secondary L-SIG 1154 following L-SIG field 706. In some embodiments, the plurality of secondary L-SIGs 1154 are followed by a second L-LTF field (L-LTF2) 1156. In other embodiments, preamble 1151 omits L-SIG 1154 and / or L-LTF2 1156. Also, in some embodiments, the preamble 1151 includes a HEW-STF 1158, one or more HEW-LTF fields 1160, and a second HEW signal field (HEW-SIGB) 1162. In other embodiments, preamble 1151 omits HEW-STF 1158, HEW-LTF 1160, and / or HEW-SIGB 1162. In one embodiment, the data unit 1150 also includes a data portion 716 (not shown in FIG. 11B). In some embodiments, multiple HEW signal fields (HEW-SIGA) 1152 are modulated using the same distance extension encoding scheme as data field 716.

  In one embodiment, one or more symbols of HEW-SIGA 1152 are modulated using, for example, QBPSK instead of BPSK, and between a standard mode and a distance extension mode by a receiving device operating according to the HEW communication protocol. Enable automatic detection. For example, in one embodiment, if the standard mode preamble includes two BPSK symbols and one Q-BPSK symbol after the L-SIG 706 field, the distance extension mode preamble is three BPSK symbols after the L-SIG 706 field and Contains one Q-BPSK symbol. For example, in one embodiment, a 4x bit format repetition of MCS0 with 48 data tones of 64 FFTs (20 MHz) each is used. For example, in some embodiments, if auto-detection distinguishes between normal mode and distance extension mode, some bits, such as bits used to indicate signal bandwidth, MCS values, or other suitable bits are HEW -Omitted from SIGA 1152.

  In one embodiment where the preamble 1151 includes one or more secondary L-SIGs 1154, the contents of each of the L-SIGs 1154 are the same as the contents of the L-SIG 706 in the data unit 1150. In one embodiment, the receiving device that receives the data unit 1150 determines that the preamble 1151 corresponds to the distance extension mode preamble by detecting repetition of the L-SIG fields 706, 1154. Furthermore, in one embodiment, both the rate subfield and length subfield of L-SIG 706, and thus the rate subfield and length subfield of secondary L-SIG1154, are set to fixed values (eg, predetermined). Is done. In this case, in one embodiment, upon detecting repetitions of multiple L-SIG fields 706, 1154, the receiving device uses a fixed value of the repeating multiple L-SIG fields as additional training information to perform channel estimation. Improve. However, in some embodiments, at least the length subfield of L-SIG 706, and thus at least the length field of secondary L-SIG 1154, is not set to a fixed value. For example, in an alternative embodiment, the length field is set to a value determined based on the actual length of the data unit 1150. In one such embodiment, the receiving device first decodes L-SIG 706 and then uses the value of the length subfield in L-SIG 706 to detect repetitions of L-SIG fields 706, 1154. In another embodiment, the receiving device first detects the repetition of the L-SIG fields 706, 1154, and then combines the detected multiple L-SIG fields 706, 1154 to deselect the L-SIG fields 706, 1154. Improve coding reliability and / or use redundant information in multiple L-SIG fields 706, 1154 to improve channel estimation.

  In embodiments where the preamble 1151 includes L-LTF2 1156, the L-LTF2 1156 OFDM symbol is generated using a distance extension coding scheme. In another embodiment, where the preamble 1151 includes L-LTF2 1156, L-LTF2 1156 OFDM symbols are generated using a standard coding scheme. For example, in one embodiment, if the double guard interval (DGI) used in L-LTF 704 is long enough for the communication channel that data unit 1150 passes from the receiving device to the transmitting device, the multiple OFDM symbols of L-LTF2 1156 are , Generated using a standard encoding scheme, or preamble 1151 omits L-LTF2 1156.

  In another embodiment, preamble 1151 omits secondary L-SIG 1154 but includes L-LTF2 1156. In this embodiment, the receiving device detects that the preamble 1151 is a distance extension mode preamble by detecting the presence of L-LTF2 1156. 12A-12B are diagrams illustrating two possible formats of LTF suitable for use as L-LTF2 1156, according to two exemplary embodiments. Referring first to FIG. 12A, in a first exemplary embodiment, L-LTF2 1200 is defined in the same way as L-LTF704, ie, by legacy communication protocols (eg, the IEEE 802.11a / n / ac standard). Is formatted as follows. Specifically, in the illustrated embodiment, L-LTF2 1200 includes a double guard interval (DGI) 1202, followed by two iterations of long training sequences 1204, 1206. Referring now to FIG. 12B, in another exemplary embodiment, L-LTF2 1208 is formatted differently than L-LTF704. Specifically, in the illustrated embodiment, L-LTF2 1208 includes first normal guard interval 1210, first iteration of long training sequence 1212, second normal guard interval 1214, and long training sequence 1216. Includes a second iteration.

  Referring again to FIG. 11B, in one embodiment, the HEW-SIGA 1152 is generated using a distance extension coding scheme. In one embodiment, the number of HEW-SIGAs 1152 is the same as the number of HEW-SIGAs 1108 of the standard mode preamble 1101. Similarly, in one embodiment, the content of HEW-SIGA 1152 is the same as the content of HEW-SIGA 1108 of standard mode preamble 1101. In other embodiments, the number and / or content of HEW-SIGA 1152 is different from the number and / or content of HEW-SIGA 1108 of standard mode preamble 1101. In one embodiment, the device receiving the data unit 1150 decodes the HEW-SIGA 1152 using a distance extension encoding scheme based on detecting that the preamble 1151 corresponds to a distance extension mode preamble. Convert HEW-SIGA 1152 appropriately as specified in the extended mode.

  In embodiments in which the preamble 1151 omits L-SIG1154 and / or L-LTF2 1156, the receiving device may use a distance extension code based on the autocorrelation of the HEW-SIGA field using a distance extension coding scheme and a standard coding scheme. It is determined whether the preamble corresponds to the distance extension mode preamble 1151 or the standard mode preamble 1101 by detecting whether the HEW-SIGA field in the preamble has been generated using a coding scheme or a standard coding scheme. 13A-13B are diagrams of a HEW-SIGA 1108 of a standard mode preamble 1101 and a HEW-SIGA 1152 of a distance extension mode preamble 1151, according to an embodiment. In the illustrated embodiment, the HEW-SIGA 1108 of the standard mode preamble 1101 includes a first NGI 1302, a first HEW-SIGA field 1304, a second NGI 1306, and a second HEW-SIGA field 1308. On the other hand, the HEW-SIGA 1152 of the distance extension mode preamble 1151 includes a first LGI 1310, a first HEW-SIGA field 1312, a second LGI 1314, and a second HEW-SIGA field 1312. In one embodiment, the receiving device performs a first autocorrelation of the HEW-SIGA field using a normal guard interval structure such as the structure illustrated in FIG. 13A, such as the structure illustrated in FIG. 13B. A second autocorrelation is performed using the long guard interval structure and a comparison of the autocorrelation results is performed. In one embodiment, if the autocorrelation of a HEW-SIGA field using a long guard interval produces a result that is large compared to the autocorrelation result of a HEW-SIGA field using a normal guard interval, the receiving device may It is determined that it corresponds to the extended mode preamble 1151. On the other hand, in one embodiment, if the autocorrelation of the HEW-SIGA field using the normal guard interval produces a result larger than the autocorrelation result of the HEW-SIGA field having the long guard interval, the receiving device Is determined to correspond to the standard mode preamble 1101.

  Referring again to FIG. 11B, in one embodiment, the preamble 1151 is formatted such that the legacy client station can determine the duration of the data unit 1150 and / or that the data unit is not compliant with the legacy communication protocol. . Further, in the embodiment, the preamble 1151 is formatted so that a client station operating according to the HEW protocol can determine that the data unit conforms to the HEW communication protocol. For example, at least two OFDM symbols immediately after L-SIG 706 of preamble 1151, such as L-SIG 1154 and / or L-LTF2 1156 and / or HEW-SIGA 1152, are modulated using BPSK modulation. In this case, in one embodiment, the legacy client station treats data unit 1150 as a legacy data unit, determines the duration of the data unit based on L-SIG 706, and accesses the medium during the determined duration. Self-control. Further, in one embodiment, one or more other OFDM symbols of preamble 1151, such as one or more of HEW-SIG 1152, are modulated using Q-BPSK modulation and data unit 1150 conforms to the HEW communication protocol. It is possible for a client station that operates in compliance with the HEW communication protocol to detect this.

  In some embodiments, the HEW communication protocol enables beamforming and / or multi-user MIMO (MU-MIMO) transmission in distance extension mode. In other embodiments, the HEW communication protocol allows only a single stream and / or only a single user transmission in distance extension mode. With continued reference to FIG. 11B, in embodiments where the preamble 1151 includes HEW-STF 1158 and HEW-LTF 1160, the AP 14 applies beamforming and / or multi-user transmission initiating the HEW-STF 1158. In other words, in one embodiment, the fields of preamble 1151 precede the HEW-STF 1158, are omni-directional, and are received by all intended recipients of data unit 1150 in multi-user mode. However, the HEW-STF field 1158 and the preamble fields following the HEW-STF field 1158 and the data portion following the preamble 1151 are beamformed and / or by different intended recipients of the data unit 1150. Includes different parts intended to be received. In one embodiment, the HEW-SIGB field 1162 includes user specific information for the intended multiple recipients of the data unit 1150 in MU-MIMO mode. The HEW-SIGB field 1162 is generated using a standard encoding scheme or a distance extension encoding scheme, depending on the embodiment. Similarly, HEW-STF 1158 is generated using a standard encoding scheme or a distance extension encoding scheme, depending on the embodiment. In one embodiment, the training sequence used for HEW-STF 1158 is a sequence defined in a legacy communication protocol, such as the IEEE 802.11ac protocol.

  On the other hand, in embodiments where preamble 1151 omits HEW-STF 1158 and HEW-LTF 1160, beamforming and MUMIMO are not enabled in the extended guard interval mode. In this embodiment, transmission by only a single user and a single stream is possible in the extended guard interval mode. In one embodiment, the receiving device obtains a single stream channel estimate based on the L-LTF field 704 and demodulates the data portion of the data unit 1150 based on the channel estimate obtained based on the L-LTF field 704. To do.

  In some embodiments, the receiver device uses the HEW-STF field 1158 to reinitiate an automatic gain control (AGC) process that receives the data portion 716. In one embodiment, the HEW-STF has the same duration (ie, 4 microseconds) as the VHT-STF. In other embodiments, the HEW-STF has a longer duration than the VHT-STF. In one embodiment, the HEW-STF has the same time domain periodicity as the VHT-STF, so there is one non-zero tone for every four tones in the frequency domain and the same tone as IEEE 802.11ac. Is used. In other embodiments with 1 / N tone spacing, the HEW-STF has one non-zero tone for every 4 × N tones. In embodiments where the overall bandwidth for a data unit is greater than 20 MHz (eg, 40 MHz, 80 MHz, etc.), the HEW-STF uses the same wider bandwidth VHT-STF as IEEE 802.11ac (ie, 40 MHz, 80 MHz, A 20 MHz VHT-STF replica for the entire bandwidth such as 160 MHz).

  FIG. 14A is a block diagram illustrating a distance extension mode data unit 1400 according to one embodiment. Data unit 1400 includes distance extension mode preamble 1401. In general, the distance extension mode preamble 1401 is similar to the distance extension mode preamble 1151 of FIG. To do. FIG. 14B is a diagram illustrating an L-SIG field 1406 according to one embodiment. In the embodiment of FIG. 14B, the L-SIG field 1406 includes a double guard interval 1410, a first L-SIG field 1412 containing the contents of the L-SIG field 706 in the preamble 1151, and a secondary L-SIG2 field in the preamble 1151. And a second L-SIG field 1414 containing the contents of 1154. In various embodiments, the L-SIG field 1406 has a length subfield set to a fixed value or set to a variable value, as described above with respect to the L-SIG fields 706, 1154 of FIG. 11B. Including. In various embodiments, the redundant (repeated) bits of L-SIG field 1406 are used for the improved channel estimation described above with respect to L-SIG fields 706, 1154 of FIG. 11B.

従って、一実施形態において、Ｌ‐ＳＩＧフィールド１４１２は、標準のＢＰＳＫではなく反転Ｑ‐ＢＰＳＫを用いて変調される。従って、一実施形態において、例えば値１のビットは−ｊに変調され、ビット値０はｊに変調されて、標準の｛１，−１｝ＢＰＳＫ変調ではなく｛ｊ，−ｊ｝変調をもたらす。一実施形態において、Ｌ‐ＳＩＧフィールド１４１２の反転Ｑ‐ＢＰＳＫ変調の結果として、レガシクライアント局は、Ｌ‐ＳＩＧフィールド１４１２を適切にデコードし、一実施形態において、Ｌ‐ＳＩＧ１４１２フィールドに基づいてデータユニット１４００の持続時間を判断し得る。他方、一実施形態においてＨＥＷプロトコルに準拠して動作するクライアント局は、Ｌ‐ＳＩＧフィールド１４１２の反復を検出するか、またはレガシクライアント局のＦＦＴウィンドウ内のＬ‐ＳＩＧフィールドの反転Ｑ‐ＢＰＳＫ変調を検出することにより、プリアンブル１４０１が距離延長モードプリアンブルであると自動検出し得る。あるいは、複数の他の実施形態において、ＨＥＷプロトコルに準拠して動作するクライアント局は、ＨＥＷ‐ＳＩＧＡフィールド１１５２の変調またはフォーマットに基づくなど、上述の他の複数の検出方法を用いて、プリアンブル１４０１が距離延長モードプリアンブルであることを検出する。 In one embodiment, a legacy client station that receives data unit 1400 assumes that L-SIG field 1406 includes a normal guard interval. As illustrated in FIG. 14C, in this embodiment, the FFT window of the L-SIG information bits assumed in the legacy client station is shifted compared to the actual L-SIG field 1412. In one embodiment, ensure that the constellation points in the FFT window correspond to BPSK modulation as expected by the legacy client station, so that the legacy client station properly decodes the L-SIG field 1412. To enable, the modulation of L-SIG field 1412 is phase shifted with respect to standard BPSK modulation. For example, in a 20 MHz OFDM symbol, when the normal guard interval is 0.8 μs and the double guard interval is 1.6 μs, the modulation of the OFDM tone k in the L-SIG field 1412 can be seen from the following equation: Shifted to the corresponding OFDM tone k of L-SIG.

Thus, in one embodiment, the L-SIG field 1412 is modulated using inverted Q-BPSK rather than standard BPSK. Thus, in one embodiment, for example, a bit with value 1 is modulated to -j and a bit value 0 is modulated to j, resulting in {j, -j} modulation rather than standard {1, -1} BPSK modulation. . In one embodiment, as a result of the inverted Q-BPSK modulation of the L-SIG field 1412, the legacy client station appropriately decodes the L-SIG field 1412, and in one embodiment, a data unit based on the L-SIG 1412 field. A duration of 1400 may be determined. On the other hand, a client station operating in accordance with the HEW protocol in one embodiment detects a repetition of the L-SIG field 1412 or performs inverted Q-BPSK modulation of the L-SIG field in the legacy client station's FFT window. By detecting, it can be automatically detected that the preamble 1401 is a distance extension mode preamble. Alternatively, in other embodiments, a client station operating in accordance with the HEW protocol may use the other detection methods described above, such as based on the modulation or format of the HEW-SIGA field 1152, to cause the preamble 1401 to Detects the distance extension mode preamble.

  Referring to FIGS. 11A-11B and 14A, in some embodiments, the long guard interval is both a standard mode preamble (eg, preamble 1101) and a distance extension mode preamble (eg, preamble 1151 or preamble 1401). Used for the first OFDM symbol. For example, referring to FIGS. 11A-11B, in one embodiment, the L-STF field 702, the L-LTF field 704 and the L-SIG fields 706, 1154, and the HEW-SIGA field 1152 use a long guard interval. Each is generated. Similarly, referring to FIG. 14A, in one embodiment, L-STF field 702, L-LTF field 704, L-SIG field 1406, and HEW-SIGA field 1152 are generated using a long guard interval. In one embodiment, the receiving device may determine whether the preamble is a standard mode preamble based on a modulation (eg, Q-BPSK) of the HEW-SIGA field 1152 in various embodiments, or based on an indication included in the HEW-SIGA field 1152. Alternatively, it may be determined whether the distance extension mode preamble is supported. Further, similar to the preamble 1151 of FIG. 11B, the preamble 1401 of FIG. 14A includes or omits the second L-LTF2 field 1156, depending on the embodiment and / or scenario.

  FIG. 15 is a block diagram illustrating the format of the HEW-SIGA field 1500 according to one embodiment. In some embodiments, data unit 1150 or HEW-SIGA field 1152 of data unit 1400 is formatted as HEW-SIGA field 1500. In some embodiments, HEW-SIGA field 1108 is formatted as HEW-SIGA field 1500. HEW-SIGA field 1500 includes a double guard interval 1502, a first repetition of HEW-SIGA field 1504, and a second repetition of HEW-SIGA field 1506. In the exemplary embodiment, the DGI is 1.8 μs and each iteration of HEW-SIGA is 3.2 μs. In one embodiment, the repeated bits in the HEW-SIGA field 1500 are used to increase the decoding reliability of the HEW-SIGA field 1500. In one embodiment, the format of HEW-SIGA field 1500 is the standard used in standard modes such as the autocorrelation of the HEW-SIGA field of the preamble using the HEW-SIGA field 1500 format and the format illustrated in FIG. 13A. Based on a comparison between the HEW-SIGA field autocorrelation of the preamble using the HEW-SIGA field format, it is used to automatically detect the distance extension mode preamble. In some embodiments, HEW-SIGA field 1500 is modulated with less redundancy compared to data portion 716. This is because the additional time domain repetition of the HEW-SIGA field 1500 provides a sufficient improvement in decoding performance.

  FIG. 16 is a block diagram illustrating an exemplary PHY processing unit that generates a plurality of standard mode data units using a standard encoding scheme, according to one embodiment. In one embodiment, referring to FIG. 1, AP 14 and client station 25-1 each include a PHY processing unit, such as a PHY processing unit 1600. In various embodiments and / or scenarios, the PHY processing unit 1600 generates a plurality of distance extension data units, such as one of the data units of FIG. 9A, FIG. 9B, FIG. 10A, or FIG. Generally, the PHY processing unit 1600 includes a scrambler 1602 that scrambles the information bitstream to reduce the occurrence of long sequences of 1s or 0s. The FEC encoder 1606 encodes a plurality of scrambled information bits to generate encoded data bits. In one embodiment, FEC encoder 1606 includes a binary convolutional code (BCC) encoder. In another embodiment, the FEC encoder 1606 includes a binary convolutional encoder followed by a puncturing block. In yet another embodiment, the FEC encoder 1606 includes a low density parity check (LDPC) encoder. The interleaver 1610 receives the encoded data bits, interleaves these bits (ie, changes the order of the bits), and a long sequence of adjacent noise bits is input to the receiver decoder. To be prevented. The constellation mapper 1614 maps the interleaved sequence of bits to constellation points corresponding to different subcarriers of the OFDM symbol. More specifically, for each spatial stream, constellation mapper 1614 converts each bit sequence of length log2 (M) into one of M constellation points.

  The output of constellation mapper 1614 is each computed by a discrete inverse Fourier transform (IDFT) unit 1618 that transforms a block of constellation points into a time domain signal. In embodiments or situations where the PHY processing unit 1600 operates to generate a plurality of data units for transmission over a plurality of spatial streams, the cyclic shift diversity (CSD) unit 1622 performs unintended beamforming. To prevent this, a cyclic shift is inserted into all but one of the plurality of spatial streams. The output of the CSD unit 1622 is provided to a guard interval (GI) insertion and windowing unit 1626 that prepends the cyclic extension of the OFDM symbol to the OFDM symbol and smooths the edge of each symbol to increase spectral attenuation. The output of the GI insertion and windowing unit 1626 is provided to an analog and radio frequency (RF) unit 1630 that converts the signal to an analog signal and upconverts the signal to an RF frequency for transmission.

  In various embodiments, the distance extension mode corresponds to the lowest data rate modulation and coding scheme (MCS) of the standard mode, and a plurality of bits of redundancy or repetition is applied to at least some fields or a plurality of data units. This results in symbol repetition, further reducing the data rate. For example, in various embodiments and / or scenarios, the distance extension mode may be a distance extension mode data unit or a data portion of a repetition of a plurality of symbols and / or a non-legacy signal field according to one or more distance extension encoding schemes described below. To bring redundancy. As an example, according to one embodiment, the plurality of standard mode data units are generated by a standard encoding scheme. In various embodiments, standard coding schemes include MCS0 (binary phase shift keying (BPSK) modulation and 1/2 coding rate) to MCS9 (quadrature amplitude modulation (QAM) and 5/6 coding rate), etc. MCS selected from a set of modulation and coding schemes (MCS), with higher order MCS corresponding to higher data rates. The distance extension mode data unit in such an embodiment is generated using a distance extension coding scheme such as modulation and coding as defined by MCS0 and added bit repetition, block encoding or symbol repetition. Further reduces the data rate.

  FIG. 17A is a block diagram of an example PHY processing unit 1700 that generates multiple distance extension mode data units using a distance extension encoding scheme, according to one embodiment. In some embodiments, the PHY processing unit 1700 generates the signal and / or data field of the distance extension mode data unit. In one embodiment, referring to FIG. 1, the AP 14 and the client station 25-1 each include a PHY processing unit, such as a PHY processing unit 1700.

  The PHY processing unit 1700 is similar to the PHY processing unit 1600 of FIG. 16 except that the PHY processing unit 1700 includes a block coder 1704 coupled to a scrambler 1702. In one embodiment, the block coder 1704 reads a plurality of input (scrambled) information bits per block at a point in time and generates several copies of each block (or each bit in the block). The interleaved bits are then interleaved according to the distance extension coding scheme and output as interleaved bits for further encoding by an FEC encoder 1706 (eg, binary convolutional encoder). In general, according to one embodiment, each block includes a number of information bits that, after being encoded by block coder 1704 and FEC encoder 1706, satisfy multiple data tones of one OFDM symbol. As an example, in one embodiment, the block coder 1704 generates two copies (12x iterations) of 12 information bits for each block to generate 24 bits to be included in one OFDM symbol. The 24 bits are then encoded by the FEC encoder 1706 at a 1/2 coding rate to produce 48 bits, which modulate the 48 data tones of the OFDM symbol (eg, using BPSK modulation). To do. As another example, in another embodiment, the block coder 1704 generates four (4x iterations) copies of each block of six information bits to generate 24 bits, which are then converted into FEC encoders. 1706, encoded at 1/2 coding rate, produces 48 bits that modulate the 48 data tones of the OFDM symbol. As yet another example, in another embodiment, the block coder 1704 generates two (2x iterations) copies of each block of 13 information bits to generate 26 bits, which are then Encoded by the FEC encoder 1706 at 1/2 coding rate to generate 52 bits that modulate the 52 data tones of the OFDM symbol. In other embodiments, block coder 1704 and FEC encoder 1706 are configured to generate 104, 208, or any suitable number of bits for modulation of the data tone of the OFDM symbol.

  In some embodiments, the block coder 1704 generates a data (or signal) field as defined by MCS0 as defined in the IEEE 802.11n standard for a 20 MHz channel, ie, 52 data per OFDM symbol. If a tone is present, apply a 4x repeating scheme. In this case, according to one embodiment, the block coder 1704 generates four copies of each block of six information bits to generate 24 bits, and then two padding bits (ie, predetermined 2 bits of value) to provide a specified number of bits (ie 26 bits for 52 data tones) to the BCC encoder, which has a coding rate of 1/2 Is used to encode the 26 bits to generate 52 encoded bits for modulating 52 data tones.

  In one embodiment, the block coder 1704 uses a “block level” repetition scheme in which each block of n bits is repeated m times in succession. As an example, if m is equal to 4 (4x iterations), block coder 1704 generates a sequence [C, C, C, C] according to one embodiment. C is a block of n bits. In another embodiment, the block coder 1704 uses a “bit level” repetition scheme in which each input bit is repeated m consecutive times. In this case, in one embodiment, if m is equal to 4 (4x iterations), the block coder 1704 generates the sequence [b1 b1 b1 b1 b2 b2 b2 b2 b3 b3 b3 b3 ...]. b1 is the first bit in the multi-bit block, b2 is the second bit, and so on. In yet another embodiment, block coder 1704 generates m number of copies of the input bits and interleaves the resulting bitstream according to any suitable code. Alternatively, in yet another embodiment, the block coder 1704 may be any suitable code, eg, a Hamming block code having a coding rate of 1/2, 1/4, etc., or 1/2, 1/4, etc. Other block codes having a coding rate of (eg, (1,2) or (1,4) block code, (12,24) block code, or (6,24) block code, (13,26) block A plurality of input bits or a plurality of blocks of input bits.

  According to one embodiment, the effective encoding rate corresponding to the combination of encoding performed by block coder 1704 and encoding performed by FEC encoder 1706 is the product of the two encoding rates. For example, in an embodiment where the block coder 1704 uses 4x iterations (or 1/4 encoding rate) and the FEC encoder 1706 uses 1/2 encoding rate, the resulting effective encoding rate is 1 Equals / 8. According to one embodiment, as a result of the reduced encoding rate compared to the encoding rate used to generate similar standard mode data units, the data rate in distance extension mode is determined by the block coder 1704. It is substantially reduced by a factor corresponding to the number of applied coding rates (eg, 1/2, 1/4, etc.).

  According to some embodiments, the block coder 1704 is the same block encoding scheme as the block encoding scheme that generates the data portion of the control mode data unit that is used to generate the signal field of the control mode data unit. Is used. For example, in one embodiment, the OFDM symbol of the signal field and the OFDM symbol of the data portion each include 48 data tones, and in this embodiment, the block coder 1704, for example, for the signal field and data portion, A scheme of repeating 2 × a plurality of 12-bit blocks is applied. In another embodiment, the data portion and signal field of the control mode data unit are generated using different block coding schemes. For example, in one embodiment, the long-range communication protocol specifies a different number of data tones per OFDM symbol in the signal field compared to the number of data tones per OFDM symbol in the data portion. Thus, in this embodiment, the block coder 1704 uses a different block size, and in some embodiments, the block size and encoding scheme used to generate the data portion when operating on the signal field. Use a different block size and encoding scheme compared to. For example, if the long-range communication protocol specifies 52 data tones per OFDM symbol in the signal field and 48 data tones per OFDM tone in the data portion, according to one embodiment, Block coder 1704 applies the 2x repeating scheme to the 13-bit blocks of the signal field and applies the 2x repeating scheme to the 12-bit blocks of the data portion.

  According to one embodiment, the FEC encoder 1706 encodes block encoded information bits. In one embodiment, BCC encoding is performed continuously over all fields generated (eg, the entire data field, the entire signal field, etc.). Thus, in this embodiment, a plurality of information bits corresponding to a generated field is divided into a plurality of blocks of a specified size (for example, 6 bits, 12 bits, 13 bits, or other suitable number of bits). Each block is processed by a block coder 1704, and the resulting data stream is then provided to the FEC encoder 1706, which sequentially encodes a plurality of input bits.

  In various embodiments, similar to the interleaver 1610 of FIG. 16, the interleaver 1710 includes a plurality of interleavers 1710 to provide diversity gain and reduce the chance that consecutive bits in the data stream are corrupted in the transmission channel. Change the order of bits. However, in some embodiments, block coder 1704 provides sufficient diversity gain and interleaver 1710 is omitted. In some embodiments, interleaver 1710 or FEC encoder 1706 provides multiple bits to constellation mapper 1614 for transmission as described above.

  In some embodiments, information bits in the data portion of the distance extension mode data unit are padded (ie, a known number of bits is added to the information bits), eg, the data unit is an integer OFDM Occupies symbols. Referring to FIG. 1, in some embodiments, padding is implemented in MAC processing units 18, 28 and / or PHY processing units 20, 29. In some such embodiments, the number of padding bits conforms to the padding equations provided in short-range communication protocols (eg, IEEE 802.11a standard, IEEE 802.11n standard, IEEE 802.11ac standard, etc.). Determined. In general, these padding equations calculate the number of padding bits based in part on the number of data bits per OFDM symbol (NDBPS) and / or the number of encoded data bits per symbol (NCBPS). Including calculating. According to one embodiment, in distance extension mode, the number of padding bits is the number of information bits in the OFDM symbol (before the plurality of information bits are block encoded by the block coder 1704 and BCC encoded by the FEC encoder 1706 ( For example, 6 bits, 12 bits, 13 bits, etc.). Accordingly, the number of padding bits in the distance extension mode data unit is generally different from the number of padding bits in the corresponding standard mode data (or corresponding short distance data unit). On the other hand, according to one embodiment, the number of coded bits per symbol is the same as the number of coded bits per symbol of a standard mode data unit (or corresponding short-range data unit), for example 1 The coded bits per OFDM are 24, 48, 52, etc.

  FIG. 17B is a block diagram of an exemplary PHY processing unit 1750 that generates multiple distance extension mode data units, according to another embodiment. In some embodiments, the PHY processing unit 1750 generates the signal and / or data field of the distance extension mode data unit. In one embodiment, referring to FIG. 1, AP 14 and client station 25-1 each include a PHY processing unit, such as a PHY processing unit 1750.

  The PHY processing unit 1750 is similar to the PHY processing unit 1700 of FIG. 17A except that in the PHY processing unit 1750, the FEC encoder 1706 is replaced with an LDPC encoder 1756. Thus, in this embodiment, the output of block coder 1704 is provided by LDPC encoder 1756 for further block encoding. In one embodiment, LDPC encoder 1756 uses a block code corresponding to a 1/2 encoding rate, or a block code corresponding to another suitable encoding rate. In the illustrated embodiment, the PHY processing unit 1750 omits the interleaver 1710, which is that multiple adjacent bits in the information stream are typically spread by the LDPC code itself and require further interleaving. Because it is not. Further, in one embodiment, further frequency diversity is provided by LDPC tone remapping unit 1760. According to one embodiment, LDPC tone remapping unit 1760 reorders the encoded information bits or blocks of encoded information bits according to a tone remapping function. In general, tone remapping functions are such that consecutive coded information bits or blocks of information bits are mapped to discontinuous tones in an OFDM symbol, and consecutive OFDM tones are adversely affected during transmission. In some cases, it is defined to facilitate data recovery at the receiver. In some embodiments, the LDPC tone remapping unit 1760 is omitted. Referring back to FIG. 17A, in various embodiments, several tail bits are typically added to each field of the data unit to properly operate the FEC encoder 1706, eg, a BCC encoder encoded each field. Make sure to return to the zero state later. In one embodiment, for example, six tail bits are inserted at the end of the data portion before the data portion is provided to the FEC encoder 1706 (eg, after the bits have been processed by the block coder 1704).

  In some embodiments, the signal field of the distance extension mode data unit has a different format compared to the signal field format of the standard mode data unit. In some such embodiments, the signal field of the distance extension mode data unit is short compared to the signal field format of the standard mode data unit. For example, in distance extension mode according to one embodiment, only one modulation and coding scheme is used, and therefore less information about modulation and coding needs to be communicated (or communicate) in the distance extension mode signal field. No information). Similarly, in one embodiment, the maximum length of the distance extension mode data unit is short compared to the maximum length of the standard mode data unit, in which case the bits required for the length subfield of the distance extension mode signal field The number decreases. As an example, in one embodiment, the distance extension mode signal field is formatted in accordance with the IEEE 802.11n standard, but specific subfields (eg, low density parity check (LDPC) subfield, space-time block coding). (STBC) subfield etc.) are omitted. Additionally or alternatively, in some embodiments, the distance extension mode signal field has a short CRC subfield (eg, less than 8 bits) compared to the cyclic redundancy check (CRC) subfield of the standard mode signal field. Including. In general, according to some embodiments, in the distance extension mode, certain signal field subfields are omitted or changed and / or certain new information is added.

  FIG. 18A is a block diagram of an example PHY processing unit 1800 that generates a plurality of distance extension mode data units using a distance extension encoding scheme, according to another embodiment. In some embodiments, the PHY processing unit 1800 generates the signal and / or data field of the distance extension mode data unit. In one embodiment, referring to FIG. 1, AP 14 and client station 25-1 each include a PHY processing unit, such as a PHY processing unit 1800.

  The PHY processing unit 1800 is similar to the PHY processing unit 1700 of FIG. 17A except that in the PHY processing unit 1800, a block coder 1808 is placed after the FEC encoder 1806. Thus, in this embodiment, the information bits are first scrambled by scrambler 1802 and encoded by FEC encoder 1806, and the FEC encoded bits are then duplicated by block coder 1808 or otherwise block encoded. Is done. In one embodiment, like the exemplary embodiment of the PHY processing unit 1700, processing by the FEC encoder 1806 is performed continuously over the entire generated field (eg, the entire data portion, the entire signal field, etc.). The Accordingly, in the present embodiment, a plurality of information bits corresponding to the generated field are first encoded by the FEC encoder 1806, and then the BCC encoded bits have a specified size (for example, 6 bits, 12 bits, 13 bits, or any other suitable number of bits). Each block is then processed by block coder 1808. As an example, in one embodiment, the FEC encoder 1806 encodes 12 information bits per OFDM symbol using a 1/2 coding rate to generate 24 BCC coded bits, BCC encoded bits are provided to block coder 1808. In one embodiment, the block coder 1808 generates two copies of each input block, interleaves the multiple bits generated according to the distance extension coding scheme, and is included in one OFDM symbol. Generate bits. In one such embodiment, the 48 bits correspond to 48 data tones generated in the IDFT processing unit 1818 using a size 64 fast Fourier transform (FFT). As another example, in another embodiment, FEC encoder 1806 encodes 6 information bits per OFDM symbol using a 1/2 encoding rate to generate 12 BCC encoded bits. The BCC encoded bits are provided to the block coder 1808. In one embodiment, the block coder 1808 generates two copies of each input block, interleaves the multiple bits generated according to the distance extension coding scheme, and is included in one OFDM symbol. Generate bits. In one such embodiment, the 24 bits correspond to 24 data tones generated in the IDFT processing unit 1818 using a size 32 FFT.

  Similar to the block coder 1704 of FIG. 17A, the distance extension encoding scheme used by the block coder 1808 to generate the signal field of the distance extension mode data unit may include the data portion of the distance extension mode data unit, depending on the embodiment. It is different or identical to the distance extension encoding scheme used by block coder 1808 to generate. In various embodiments, block coder 1808 implements the “block level” or “bit level” iteration scheme described above with respect to block coder 1704 of FIG. 17A. Similarly, in another embodiment, the block coder 1808 generates a copy of m number of input bits to interleave the resulting bitstream according to a suitable code, or any other A suitable code, for example, a Hamming block code having a coding rate of 1/2, 1/4, or any other block code having a coding rate of 1/2, 1/4, etc. ) Or (1,4) block code, (12,24) block code, or (6,24) block code, (13,26) block code, etc.) Encode a block of generated bits. According to one embodiment, the effective coding rate for data units generated by the PHY processing unit 1800 is the coding rate used by the FEC encoder 1806 and the number of iterations (or coding rate) used by the block coder 1808. Product.

  In one embodiment, the block coder 1808 provides sufficient diversity gain and the interleaver 1810 is omitted because no further interleaving of the coded bits is required. One advantage of omitting the interleaver 1810 is that in this case, an OFDM symbol with 52 data tones is 4x or even in some such situations, even if the number of data bits per symbol is not an integer. It can be generated using a 6x iterative scheme. For example, in one such embodiment, the output of FEC encoder 1806 is divided into a plurality of 13-bit blocks, with each block repeated four times (or block encoded at a quarter rate), one 52 bits to be included in the OFDM symbol are generated. In this case, when the FEC encoder 1806 uses an encoding rate of 1/2, the number of data bits per symbol is equal to 6.5. In an exemplary embodiment using 6x iterations, the FEC encoder 1806 encodes information bits using a 1/2 coding rate and its output is divided into multiple blocks of 4 bits. The block coder 1808 adds 4 padding bits by repeating each block of 4 bits 6 times (or by encoding each block using a coding rate of 1/6) and adding it to one OFDM symbol. Generate 52 bits to be included.

  When padding is used by the PHY processing unit 1800 as in the example of the PHY processing unit 1700 in FIG. 17A described above, the number of data bits per symbol (NDBPS) used for padding bit calculation is the non-number in the OFDM symbol. The actual number of redundant data bits (eg, 6 bits, 12 bits, 13 bits, or other suitable number of bits in the above example). The number of coded bits per symbol (NCBPS) used in the padding bit calculation is equal to the number of bits actually contained in one OFDM symbol (eg, 24 bits, 48 bits, 52 bits, or OFDM symbols) Other suitable number of bits).

  Also, as in the example of the PHY processing unit 1700 of FIG. 17A, several tail bits are typically inserted into each field of the data unit to properly operate the FEC encoder 1806, for example, the BCC encoder Make sure to return to zero after encoding. In one embodiment, for example, six tail bits are inserted at the end of the data portion before the data portion is provided to the FEC encoder 1806 (ie, after processing by the block coder 1704 is performed). Similarly, for signal fields, according to one embodiment, the tail bits are inserted at the end of the signal field before the signal field is provided to the FEC encoder 1806. In an exemplary embodiment where the block coder 1808 uses a 4x repeating scheme (or another block code that uses a 1/4 coding rate), the FEC encoder 1806 uses a 1/2 coding rate; The signal field includes 24 information bits (including tail bits), and these 24 signal field bits are BCC encoded to generate 48 BCC encoded bits, which are 4 bits of 12 bits. Each is divided into blocks and further encoded by a block coder 1808. Thus, in this embodiment, the signal field is transmitted over four OFDM symbols, each of which includes six information bits of the signal field.

  Further, in some embodiments, the PHY processing unit 1800 generates a plurality of OFDM symbols having 52 data tones according to MCS0 as defined in the IEEE 802.11n standard or the IEEE 802.11ac standard, and the block coder 1808 includes: A 4x iterative scheme is used. In some such embodiments, additional padding is used to ensure that the resulting encoded data stream to be included in one OFDM symbol contains 52 bits. In one such embodiment, padding bits are added to the encoded information bits after the bits are processed by block coder 1808.

  In the embodiment of FIG. 18A, the PHY processing unit 1800 also includes a peak to average power ratio (PAPR) reduction unit 1809. In one embodiment, the PAPR reduction unit 1809 flips bits in some or all of the repeated blocks to reduce or eliminate the occurrence of identical bit sequences at different frequency locations within the OFDM symbol, This reduces the peak-to-average power ratio of the output signal. In general, a bit flip involves changing a 0 bit value to a 1 bit value and changing a 1 bit value to a 0 bit value. According to one embodiment, the PAPR reduction unit 1809 implements bit flips using XOR operations. For example, in an embodiment using 4x repetitions of a block of coded bits, one block of coded bits contained in one OFDM symbol is denoted C and C ′ = C XOR 1 (ie, block If C has flipped bits), according to some embodiments, some possible bit sequences at the output of the PAPR reduction unit 1809 are [C C ′ C ′ C ′], [C ′ C 'C' C], [C C 'C C'], [C C C C '], and the like. In general, any combination of blocks with flipped bits and blocks with non-fliped bits can be used. In some embodiments, the PAPR unit 1809 is omitted.

  FIG. 18B is a block diagram of an example PHY processing unit 1850 that generates multiple distance extension mode data units, according to another embodiment. In some embodiments, the PHY processing unit 1850 generates the signal and / or data field of the distance extension mode data unit. In one embodiment, referring to FIG. 1, AP 14 and client station 25-1 each include a PHY processing unit, such as a PHY processing unit 1850.

  The PHY processing unit 1850 is similar to the PHY processing unit 1800 of FIG. 18A except that in the PHY processing unit 1850, the FEC encoder 1806 is replaced with an LDPC encoder 1856. Thus, in this embodiment, the information bits are first encoded by LDPC encoder 1856, and the LDPC encoded bits are then duplicated by block coder 1808 or otherwise block encoded. In one embodiment, LDPC encoder 1856 uses a block code that corresponds to a 1/2 encoding rate, or a block code that corresponds to another suitable encoding rate. In the illustrated embodiment, the PHY processing unit 1850 omits the interleaver 1810, since multiple adjacent bits in the information stream are typically spread by the LDPC code itself, according to one embodiment. This is because no further interleaving is required. Further, in one embodiment, further frequency diversity is provided by LDPC tone remapping unit 1860. According to one embodiment, LDPC tone remapping unit 1860 reorders the encoded information bits or blocks of encoded information bits according to a tone remapping function. In general, tone remapping functions are such that consecutive coded information bits or blocks of information bits are mapped to discontinuous tones in an OFDM symbol, and consecutive OFDM tones are adversely affected during transmission. In some cases, it is defined to facilitate data recovery at the receiver. In some embodiments, the LDPC tone remapping unit 1860 is omitted.

  FIG. 19A is a block diagram of an example PHY processing unit 1900 that generates multiple distance extension mode data units, according to another embodiment. In some embodiments, the PHY processing unit 1900 generates the signal and / or data field of the distance extension mode data unit. In one embodiment, referring to FIG. 1, the AP 14 and the client station 25-1 each include a PHY processing unit, such as a PHY processing unit 1900.

  The PHY processing unit 1900 is similar to the PHY processing unit 1800 of FIG. 18A except that in the PHY processing unit 1900, a block coder 1916 is placed after the constellation mapper 1914. Therefore, in this embodiment, after being processed by the interleaver 1910, the BCC encoded information bits are mapped to constellation symbols, and then the constellation symbols are duplicated or separately block encoded by a block coder 1916. . According to one embodiment, processing by the FEC encoder 1906 is performed continuously over the entire generated field (eg, the entire data field, the entire signal field, etc.). In this embodiment, a plurality of information bits corresponding to the generated field are first encoded by the FEC encoder 1806 and then the BCC encoded bits are mapped to constellation symbols by the constellation mapper 1914. The constellation symbols are then divided into a plurality of blocks of a specified size (eg, 6 symbols, 12 symbols, 13 symbols, or other suitable number of symbols), and each block is then processed by a block coder 1916. It is processed. As an example, in an embodiment using 2x iterations, the constellation mapper 1914 generates 24 constellation symbols, and the block coder 1916 generates two copies of the 24 symbols (e.g., 48 symbols corresponding to the 48 data tones of the OFDM symbol are generated (as specified in the IEEE 802.11a standard). As another example, in an embodiment using 4x iterations, constellation mapper 1914 generates 12 constellation symbols and block coder 1916 generates 4 copies of 12 constellation symbols. , Generate 48 symbols corresponding to the 48 data tones of the OFDM symbol (eg, as specified in the IEEE 802.11a standard). As yet another example, in an embodiment using 2x iterations, the constellation mapper 1914 generates 26 constellation symbols, and the block coder 1916 repeats 26 symbols (ie, 26 symbols). Generate two copies of the symbol), and generate 52 symbols corresponding to the 52 data tones of the OFDM symbol (eg, as specified in the IEEE 802.11n standard or the IEEE 802.11ac standard). In general, in various embodiments and / or scenarios, block coder 1916 generates any suitable number of copies of a plurality of blocks of input constellation symbols, and any suitable encoding of the generated symbols. Interleave according to the scheme. Similar to block coder 1704 of FIG. 17A and block coder 1808 of FIG. 18A, the distance extension coding scheme used by block coder 1916 to generate one signal field (or multiple signal fields) of the distance extension mode data unit is Depending on the embodiment, the distance extension encoding scheme used by the block coder 1916 to generate the data portion of the distance extension mode data unit is different or the same. According to one embodiment, the effective coding rate for the data units generated by the PHY processing unit 1900 is the coding rate used by the FEC encoder 1906 and the number of iterations (or coding rate) used by the block coder 1916. The product of

  According to one embodiment, in this case, redundancy is provided after information bits are mapped to constellation symbols, so that each OFDM symbol generated by PHY processing unit 1900 is OFDM data included in a standard mode data unit. Contains fewer non-redundant data tones compared to tones. Accordingly, the interleaver 1910 is per OFDM symbol compared to the interleaver used in the standard mode (eg, interleaver 1610 in FIG. 16) or the interleaver used when generating the corresponding short-range data unit. Designed to operate on a smaller number of tones. For example, in an embodiment using 12 non-redundant data tones per OFDM symbol, the interleaver 1910 has 6 columns (Ncol) and rows (Nrow) bits per subcarrier (Nbpscs) × Designed to use 2. In another exemplary embodiment using 12 non-redundant data tones per OFDM symbol, interleaver 1910 is designed to use Ncol of 4 and Nrow of Nbpscs × 3. In other embodiments, other interleaver parameters are used for interleaver 1910 that are different from the interleaver parameters used in the standard mode. Alternatively, in one embodiment, the block coder 1916 provides sufficient diversity gain, and no further interleaving of the coded bits is required, so the interleaver 1910 is omitted. In this case, as in the exemplary embodiment using the PHY processing unit 1800 of FIG. 18A, 52 data tones are obtained even if the number of data bits per symbol is not an integer in some such situations. Having an OFDM symbol can be generated using a 4x or 6x repeating scheme.

  When padding is used by the PHY processing unit 1900 as in the exemplary embodiment of the PHY processing unit 1700 in FIG. 17A above, or the PHY processing unit 1800 in FIG. 18A above, 1 used for padding bit calculation. The number of data bits per symbol (NDBPS) is the actual number of non-redundant data bits in one OFDM symbol (eg, 6 bits, 12 bits, 13 bits, or other suitable number of bits in the example above) . The number of coded bits per symbol (NCBPS) used in the padding bit calculation is equal to the number of non-redundant bits contained in one OFDM symbol, in this case the constellation processed by the block coder 1916. Corresponding to the number of bits in the block of the symbol (for example, 12 bits, 24 bits, 26 bits, etc.).

  In some embodiments, the PHY processing unit 1900 generates a plurality of OFDM symbols with 52 data tones according to MCS0 as defined in the IEEE 802.11n standard or the IEEE 802.11ac standard, and the block coder 1916 includes 4 × Use an iterative scheme. In some such embodiments, additional padding is used to ensure that the resulting encoded data stream to be included in one OFDM symbol contains 52 bits. In one such embodiment, padding bits are added to the encoded information bits after the bits are processed by block coder 1808.

  In the embodiment of FIG. 19A, the PHY processing unit 1900 includes a peak to average power ratio (PAPR) reduction unit 1917. In one embodiment, the peak-to-average power ratio unit 1917 adds a phase shift to some of the data tones that are modulated using repetitive constellations. For example, in one embodiment, the added phase shift is 180 °. A 180 ° phase shift corresponds to a sign flip of the bits that modulate the data tone in which the phase shift is implemented. In another embodiment, the PAPR reduction unit 1917 adds a phase shift other than 180 ° (eg, a 90 ° phase shift or other suitable phase shift). As an example, in one embodiment using 4x iterations, one block of 12 constellation symbols to be included in the OFDM symbol is denoted C, resulting in a simple block iteration being performed. The sequence made is [C CC C]. In some embodiments, the PAPR reduction unit 1917 provides a sign flip (ie, -C) or 90 ° phase shift (ie, j * C) for some of the repeated blocks. In some such embodiments, the resulting sequence can be, for example, [C-C-C-C], [-C-C-C-C], [C-C C-C], [C C C C-C], [C j * C, j * C, j * C], or other combinations of C, -C, j * C and j * C. In general, in various embodiments and / or scenarios, a suitable phase shift may be provided for any repeated block. In some embodiments, the PAPR reduction unit 1809 is omitted.

  In some embodiments, the PHY processing unit 1900 generates a plurality of OFDM symbols with 52 data tones according to MCS0 as defined in the IEEE 802.11n standard or the IEEE 802.11ac standard, and the block coder 1916 includes 4 × Use an iterative scheme. In some such embodiments, additional pilot tones are inserted to ensure that the number of resulting data tones and pilot tones in one OFDM symbol is equal to 56 as specified in the short-range communication protocol. To. As an example, in one embodiment, 6 information bits are BCC encoded at a coding rate of 1/2 and the resulting 12 bits are mapped to 12 constellation symbols (BPSK). The 12 constellation symbols modulate 12 data tones, which are then repeated 4 times to produce 48 data tones. As specified in the IEEE 802.11n standard, four pilot tones are added, and four more pilot tones are added to generate 56 data tones and pilot tones.

  FIG. 19B is a block diagram of an example PHY processing unit 1950 that generates multiple distance extension mode data units, according to another embodiment. In some embodiments, the PHY processing unit 1950 generates the signal and / or data field of the distance extension mode data unit. In one embodiment, referring to FIG. 1, AP 14 and client station 25-1 each include a PHY processing unit, such as a PHY processing unit 1950.

  The PHY processing unit 1950 is similar to the PHY processing unit 1900 of FIG. 19A except that in the PHY processing unit 1950, the FEC encoder 1906 is replaced with an LDPC encoder 1956. Therefore, in this embodiment, LDPC encoded information bits are mapped to constellation symbols by constellation mapper 1914, and then the constellation symbols are duplicated or separately block encoded by block coder 1916. In one embodiment, LDPC encoder 1956 uses a block code that corresponds to a 1/2 encoding rate, or a block code that corresponds to another suitable encoding rate. In the illustrated embodiment, the PHY processing unit 1950 omits the interleaver 1910, which is that multiple adjacent bits in the information stream are typically spread by the LDPC code itself, according to one embodiment. This is because no further interleaving is required. Further, in one embodiment, additional frequency diversity is provided by LDPC tone remapping unit 1960. According to one embodiment, LDPC tone remapping unit 1960 reorders the encoded information bits or blocks of encoded information bits according to a tone remapping function. In general, tone remapping functions are such that consecutive coded information bits or blocks of information bits are mapped to discontinuous tones in an OFDM symbol, and consecutive OFDM tones are adversely affected during transmission. In some cases, it is defined to facilitate data recovery at the receiver. In some embodiments, the LDPC tone remapping unit 1960 is omitted.

  In the embodiments described above with respect to FIGS. 17A-19B, the distance extension mode provides redundancy by repeating bits and / or constellation symbols in the frequency domain. Alternatively, in some embodiments, the distance extension coding scheme includes a data field of a distance extension mode data unit that is performed in the repetition and / or time domain of OFDM symbols in the signal. For example, FIG. 20A is a diagram illustrating that each OFDM symbol of the HT-SIG1 field and the HT-SIG2 field in the preamble of the distance extension mode data unit is repeated 2x according to an embodiment. Similarly, FIG. 20B is a diagram illustrating that each OFDM symbol of the L-SIG field in the preamble of the distance extension mode data unit is repeated 2x according to one embodiment. FIG. 20C is a diagram illustrating a time-domain repetition scheme of OFDM symbols in the data portion of the control mode data unit, according to one embodiment. FIG. 20D is a diagram illustrating an OFDM symbol repetition scheme in a data portion according to another embodiment. As shown, in the embodiment of FIG. 20C, OFDM symbol repetitions are output in succession, whereas in the embodiment of FIG. 20D, OFDM symbol repetitions are interleaved. In general, in various embodiments and / or scenarios, OFDM symbol repetitions are interleaved according to any suitable interleaving scheme.

  FIG. 21 is a flow diagram of an exemplary method 2100 for generating data units according to one embodiment. Referring to FIG. 1, the method 2100 is implemented by the network interface 16 in one embodiment. For example, in one such embodiment, PHY processing unit 20 is configured to implement method 2100. According to another embodiment, the MAC process 18 is configured to implement at least a portion of the method 2100. With continued reference to FIG. 1, in yet another embodiment, method 2100 is implemented by network interface 27 (eg, PHY processing unit 29 and / or MAC processing unit 28). In other embodiments, the method 2100 is implemented by several other suitable network interfaces.

  At block 2102, the information bits to be included in the data unit are encoded according to the block code. In one embodiment, the information bits are encoded using, for example, the block level or bit level repetition scheme described above with respect to block coder 1704 of FIG. 17B. At block 2104, the information bits are encoded using, for example, an FEC encoder such as the FEC encoder 1706 of FIG. 17A or the LDPC encoder 1756 of FIG. 17B. At block 2106, information bits are mapped to constellation symbols. At block 2108, a plurality of OFDM symbols are generated to include constellation points. At block 2110, a data unit that includes an OFDM symbol is generated.

  In one embodiment, as illustrated in FIG. 21, the information bits are first encoded using a block encoder (block 2102), and then the block encoded bits are, for example, those described above with respect to FIG. 17A, etc. Encoded using a FEC encoder (block 2104). In another embodiment, the order of block 2102 and block 2104 is reversed. Thus, in this embodiment, the information bits are first FEC encoded and the FEC encoded bits are encoded according to a block encoding scheme such as that described above with respect to FIG. 18A, for example. In yet another embodiment, block 2102 is placed after block 2106. In this embodiment, the information bits are FEC encoded at block 2104, the FEC encoded bits are mapped to constellation symbols at block 2106, and then at block 2102 the constellation symbols are, for example, with respect to FIG. 19A. Encoded according to a block coding or repetition scheme as described above.

  In various embodiments, the distance extension coding scheme uses a reduced size Fast Fourier Transform (FFT) technique that outputs a reduced number of constellation symbols, where the constellation symbols are repeated across the bandwidth, Improve distance and / or SNR performance. For example, in one embodiment, the constellation mapper maps a sequence of bits to a plurality of constellation symbols corresponding to 32 subcarriers having 24 data tones (eg, 32 point FFT mode). . The 32 subcarriers correspond to the 10 MHz subband in the entire 20 MHz bandwidth. In this example, the constellation symbols are repeated throughout the 20 MHz bandwidth to provide constellation symbol redundancy. In various embodiments, the reduced size FFT technique is used in combination with the bit format and / or symbol replication techniques described above with respect to FIGS. 17A-19B.

  In some embodiments where additional bandwidth is available, such as 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz, 32 subcarriers are repeated across each 10 MHz subband of the entire bandwidth. For example, in another embodiment, a 32 point FFT mode corresponds to a 5 MHz subband of the entire 20 MHz bandwidth. In this embodiment, the constellations are repeated 4x across the entire 20 MHz bandwidth (ie, each subband of 5 MHz). Accordingly, the receiving device combines a plurality of constellations to improve the reliability of constellation decoding. In some embodiments, the modulation of different 5 or 10 MHz subband signals is rotated at different angles. For example, in one embodiment, the first subband rotates 0 °, the second subband rotates 90 °, the third subband rotates 180 °, and the fourth subband rotates 270 °. In other embodiments, different suitable rotations are used. In at least some embodiments, the plurality of different phases of the 20 MHz subband signal results in a reduction in OFDM symbol peak-to-average power ratio (PAPR) in the data unit.

  FIG. 22A is a diagram of the entire 20 MHz bandwidth with 2 × iterations of a distance extension data unit having a 10 MHz subband, according to one embodiment. As shown in FIG. 22A, each subband of 10 MHz is rotated by rotations r1 and r2. FIG. 22B is a diagram of the entire 40 MHz bandwidth with 4 × repetitions of a distance extension data unit having a 10 MHz subband, according to one embodiment. As shown in FIG. 22B, each subband of 10 MHz is rotated by rotations r1, r2, r3, and 4, respectively. FIG. 22C is a diagram of an exemplary tone plan 2230 in 32-point FFT mode corresponding to a 10 MHz subband, according to one embodiment. Tone plan 2230 has a total of 24 data tones, two pilot tones at indices +7 and -7, one direct tone, and five guard tones, as shown in FIG. 22C. Includes 32 tones. In embodiments where a reduced size FFT technique is used, a corresponding tone plan is used for the HEW-LTF field, if present. In other embodiments where a reduced size FFT technique is used, but no HEW-LTF field is present, the L-LTF field 704 is a pilot tone for the corresponding index of the modified tone plan. Modified to include an additional ± 1 sign. For example, in one embodiment, tones -29, -27, +27 and +29 are added to the tone plan for the L-LTF field. In a further embodiment, the ± 1 sign is removed from the L-LTF tone plan in tones -2, -1, 1 and 2 with a 20 MHz bandwidth. Similar changes apply to the entire bandwidth, such as 40 MHz, 80 MHz, 160 MHz.

  FIG. 23 is a diagram of an example data unit 2300 in which the distance extension mode is used for the data unit preamble 2301, according to one embodiment. In some embodiments, the preamble 2301 exhibits both a standard mode and a distance extension mode. In one such embodiment, another method is used to distinguish between standard mode and distance extension mode, such as those described above with respect to FIGS. 9A, 9B, 10A, 10B, and 11A, 11B.

  Data unit 2301 is generally similar to data unit 1150 of FIG. 11B and includes the same numbered elements, except that preamble 2301 of data unit 2300 is formatted differently from preamble 1151 of data unit 1101. . In one embodiment, the preamble 2301 is formatted such that a receiving device operating according to the HEW communication protocol can determine that the preamble 2301 is not a standard mode preamble but a distance extension mode preamble. In one embodiment, compared to data unit 1151, preamble 2301 includes a modified long training field M-LTF 2304 and a modified signal field M-SIG 2306, respectively, instead of L-LTF 704 and L-SIG 706. In one embodiment, preamble 2301 includes a double guard interval followed by two iterations of a long training sequence modified as L-STF 702, M-LTF 2304, a normal guard interval, and a modified signal field M-SIG. In some embodiments, the preamble 2301 further includes one or more first HEW signal fields (HEW-SIGA) 1152. In one embodiment, the preamble 2301 further includes one or more secondary L-SIGs 1154 following the L-SIG field 2306. In some embodiments, the plurality of secondary L-SIGs 1154 are followed by a second L-LTF field (L-LTF2) 1156. In other embodiments, the preamble 2301 omits the L-SIG 1154 and / or L-LTF2 1156. Also, in some embodiments, the preamble 2301 includes a HEW-STF 1158, one or more HEW-LTF fields 1160, and a second HEW signal field (HEW-SIGB) 1162. In other embodiments, preamble 2301 omits HEW-STF 1158, HEW-LTF 1160, and / or HEW-SIGB 1162. In one embodiment, the data unit 2300 also includes a data portion 716 (not shown in FIG. 23). In some embodiments, multiple HEW signal fields (HEW-SIGA) 1152 are modulated using the same distance extension encoding scheme as data field 716.

式中、Ｃは、予め定められたシーケンスである。いくつかの実施形態において、Ｍ‐ＳＩＧ２３０６は、方程式２に示されるように、予め定められたシーケンスを掛けたＬ‐ＳＩＧ７０６に対応する。

いくつかの実施形態において、予め定められたシーケンスの長さ（すなわち、値の数）は、ＩＥＥＥ８０２．１１ａｃプロトコルにおける２０ＭＨｚ帯域当たりのデータトーンの数およびパイロットトーンの数の合計、例えば５２の値（すなわち、４８個のデータトーンおよび４のパイロットトーン）に等しい。 In various embodiments, M-LTF 2304 corresponds to L-LTF 704 multiplied by a predetermined sequence (eg, a polarization code). For example, using index i, the i-th constellation symbol of L-LTF 704 is multiplied by the i-th value of a predetermined sequence (eg, ± 1) as shown in Equation 1, and M-LTF 2304 is obtain.

In the formula, C is a predetermined sequence. In some embodiments, M-SIG 2306 corresponds to L-SIG 706 multiplied by a predetermined sequence, as shown in Equation 2.

In some embodiments, the predetermined sequence length (ie, the number of values) is the sum of the number of data tones and pilot tones per 20 MHz band in the IEEE 802.11ac protocol, eg, a value of 52 ( That is, 48 data tones and 4 pilot tones).

  In one embodiment, the predetermined sequence and the modified long training sequence each have a length that is greater than or equal to the sum of the number of data tones and the number of pilot tones. If the HEW-STF and / or HEW-LTF fields are not present in the distance extension preamble, as described above with respect to the 32-point FFT mode tone plan 2230 corresponding to the 10 MHz subband, the receiver Depends on the L-LTF field for demodulation. In one embodiment, a tone plan mismatch between a 20 MHz L-LTF and a 10 MHz 32 point FFT mode results in unknown tones (eg, tones -29, -27, +27 and +29 for a total of 58 tones). Is corrected by inserting a code of +1 or −1 in the L-LTF for.

  FIG. 24 is a block diagram of an exemplary PHY processing unit 2400 that generates multiple distance extension mode data units, according to another embodiment. In some embodiments, the PHY processing unit 2400 generates a distance extension mode data unit signal and / or training field. In one embodiment, referring to FIG. 1, AP 14 and client station 25-1 each include a PHY processing unit, such as PHY processing unit 2400.

  The PHY processing unit 2400 is similar to the PHY processing unit 1700 of FIG. 17A except that in the PHY processing unit 2400, a tone multiplier 2404 is placed after the constellation mapper 1614. In some embodiments, tone multiplier 2404 includes i) a modified constellation symbol for the L-SIG field (ie, M-SIG 2306), and ii) the L-LTF field (ie, M-) of the distance extension mode data unit. Generate a modified long training sequence for LTF 2304).

  In some embodiments, the PHY processing unit 2400 generates at least a first long training sequence for the distance extension mode preamble by multiplying the predetermined sequence by the second long training sequence of the second communication protocol. Configured to generate. In one embodiment, for example, tone multiplier 2404 multiplies a predetermined sequence with L-LTF 704 to obtain M-LTF 2304. In one embodiment, tone multiplier 2404 provides M-LTF 2304 to IDFT 1618 instead of L-LTF 704 during distance extension mode.

  In one embodiment, tone multiplier 2404 receives constellation symbols for data to be included in L-SIG 706 from constellation mapper 1614 and constellation symbols for pilot tones from pilot tone generator 2408. Thus, in one embodiment, M-SIG 2306 output from tone multiplier 2404 includes modified constellation symbols for data tones and pilot tones that are to be converted to time domain signals by IDFT 1618.

式中、ｙ_ｉは、最後に受信されて平均されたＬ‐ＬＴＦシーケンスであり、Ｌ_ｉは、ＩＥＥＥ８０２．１１ａ／ｎ／ａｃに属する送信されたＬ‐ＬＴＦシーケンス、または修正されたロングトレーニングシーケンスＭ‐ＬＴＦである。例えば、Ｌ_ｉは距離延長モードのＣ_ｉ＊Ｌ‐ＬＴＦ_ｉまたは標準モードのＬ‐ＬＴＦ_ｉのいずれかである。いくつかのシナリオにおいて、連続するトーンの相互相関は一般に、チャネル効果を除去し、周波数領域一致フィルタリングは、可能性が最も高い送信されたシーケンスを発見する。いくつかの実施形態において、レシーバデバイスは、Ｍ‐ＬＴＦからのチャネル推定を用いて、データユニットの追加のフィールド（すなわち、ＨＥＷ‐ＳＩＧおよび／またはデータフィールド）をデコードする。いくつかのシナリオにおいて、パイロットトーンに対応する予め定められたシーケンスの値は全て１であり、パイロットトーンに対する位相トラッキングを可能にする。 In some embodiments, the receiver device decodes M-SIG 2306 using, for example, channel estimation based on M-LTF 2304. In this example, both L-LTF 704 and L-SIG 706 are multiplied by a predetermined sequence so that the legacy receiver device substantially eliminates multiplication as part of the channel estimation or autocorrelation processing. In one embodiment, the receiving device uses (eg, multiplies with) a predetermined sequence based on autocorrelation of L-LTF fields with or without a predetermined sequence multiplication. ), Or by multiplying the preamble by the distance extension mode preamble 2400 by detecting whether an LTF field in the preamble (eg, either M-LTF 2304 or L-LTF 704) has been generated without being multiplied by a predetermined sequence. Alternatively, it is determined whether it corresponds to the standard mode preamble 1101. In one embodiment, the receiving device performs LTF first autocorrelation using L-LTF 704, performs LTF second autocorrelation using M-LTF2304, and performs a comparison of autocorrelation results. To do. In one embodiment, if the autocorrelation using M-LTF 2304 produces a large result compared to the autocorrelation result using L-LTF 704, the receiving device determines that the preamble corresponds to distance extension mode preamble 2300. On the other hand, in one embodiment, if the autocorrelation of the LTF using L-LTF 704 produces a result that is large compared to the autocorrelation result using M-LTF 2304, the receiving device may determine that the preamble corresponds to the standard mode preamble 1101. to decide. In some embodiments, the receiver device performs autocorrelation in the frequency domain according to Equation 3.

Where y _i is the last received and averaged L-LTF sequence, and L _i is the transmitted L-LTF sequence belonging to IEEE 802.11a / n / ac, or a modified long training sequence M-LTF. For example, _{L i} is either _{C i} * L-LTF i or standard mode L-LTF _i of distance extension mode. In some scenarios, cross-correlation of consecutive tones generally removes channel effects, and frequency domain matched filtering finds the most likely transmitted sequence. In some embodiments, the receiver device uses channel estimation from the M-LTF to decode additional fields of the data unit (ie, HEW-SIG and / or data field). In some scenarios, the value of the predetermined sequence corresponding to the pilot tone is all 1, allowing phase tracking for the pilot tone.

  In some embodiments, OFDM modulation with reduced tone spacing uses the same size FFT to reduce the data rate of distance extension mode. For example, the standard mode for an OFDM data unit with a 20 MHz bandwidth results in 64 OFDM tones using a 64-point Fast Fourier Transform (FFT), while the distance extension mode reduces the tone by a factor of two. The spacing is used to yield 128 OFDM tones of the same bandwidth. In this case, using the same 64 point FFT, 2x increased symbol duration, and 2x increased guard interval, the tone spacing in the distance extended mode OFDM symbol is 2 compared to the standard mode OFDM symbol. The symbols are then reduced by a factor (1/2) and then the symbols are repeated with the remaining bandwidth. As another example, the standard mode for a 20 MHz bandwidth OFDM data unit provides 64 OFDM tones using a 64 point Fast Fourier Transform (FFT), while the distance extension mode applies to a 20 MHz OFDM data unit. A tone spacing reduced to ¼ results in 256 OFDM tones of the same bandwidth. In this case, while using a symbol duration increased to 4x and a guard interval increased to 4x, the tone spacing in the distance extended mode OFDM symbol is a quarter (1/4) compared to the standard mode OFDM symbol. ) Is made smaller. In several such embodiments, for example, a long GI duration of 1.6 μs is used. However, in one embodiment, the duration of the information portion in the distance extension mode OFDM symbol is increased (eg, from 3.2 μs to 6.4 μs), and the percentage of the duration of the GI portion relative to the total duration of the OFDM symbol is: Still the same. Thus, in this case, in at least some embodiments, efficiency loss due to longer GI symbols is avoided. In various embodiments, the term “long guard interval” as used herein includes an increased duration of the guard interval and a reduced OFDM tone interval that substantially increases the duration of the guard interval. In other embodiments, according to a factor of 6, 8, or other suitable value, the tone spacing is reduced, the guard interval is increased, and the symbol duration is increased. In some embodiments, as described above, changes in tone spacing, guard interval, and symbol duration are used in combination with block coding or symbol repetition.

  The total signal bandwidth of the data unit in distance extension mode in some embodiments is 20 MHz. For example, it is unlikely that increased signal bandwidth will further increase distance or improve SNR performance. In some embodiments, the distance extension mode is configured to use an FFT size of up to 512 points. In one such embodiment, for distance extension mode, if the tone spacing is reduced by a quarter, the total bandwidth of the 512 point FFT is 40 MHz, and therefore distance extension mode is a signal of up to 40 MHz. Use bandwidth.

  In other embodiments, the distance extension mode is configured for up to the maximum available signal bandwidth (eg, 160 MHz). In various embodiments, for example, the 1/2 tone spacing is 64 FFTs for the 10 MHz band, 128 FFTs for the 20 MHz band, 256 FFTs for the 40 MHz band, 512 FFTs for the 80 MHz band, and 160 MHz. Corresponds to an FFT of 1024 points for the band. In some embodiments, the reduced tone spacing is used in combination with a smaller FFT size. In various embodiments, a shorter guard interval, eg, a normal guard interval having a duration equal to 25% of the duration of the OFDM symbol, and a short guard interval having a duration equal to 1/9 of the OFDM symbol has been reduced. Used with tone spacing.

  In some embodiments, the distance extension mode uses smaller tone spacing (ie 1/2, 1/4, etc.). In one such embodiment, the same FFT size represents a smaller bandwidth, for example, a 1/2 tone spacing corresponds to a 64 point FFT for a 10 MHz band. In one embodiment, the tone plan within the same FFT size is the same for both distance extension mode and standard mode, for example, a 64-point FFT in distance extension mode is equivalent to a 64-point FFT for 20 MHz in IEEE 802.11ac. Use the same tone plan. FIG. 25A is an exemplary 20 MHz full bandwidth diagram with 1/2 tone spacing, according to one embodiment. In this case, the original DC tone index of the legacy tone plan for each 64 point FFT is not in the middle of the total bandwidth of 20 MHz, but here in the middle of the 10 MHz subband, and the index of the original guard tone is Approximate a true DC tone. In some embodiments where the bandwidth used for the distance extension mode data unit is less than 20 MHz, the non-legacy tone plan includes additional data or pilot tones in the index of the original DC tone. This is because the index does not overlap with the “true DC tone” and the smallest signal bandwidth is 20 MHz in distance extension mode or standard mode. In some embodiments, the non-legacy tone plan includes additional data tones instead of guard tones at the end of the legacy tone plan to retain the same number of populated tones.

  In other embodiments, the smaller the tone spacing, the greater the effects from DC offset and carrier frequency offset (CFO) compared to standard mode. FIG. 25B is an exemplary 20 MHz full bandwidth diagram with 1/2 tone spacing, according to one embodiment. In some embodiments, the additional zero tone is defined as being closer to the DC tone in the band of the non-legacy tone plan in distance extension mode compared to the same FFT size legacy tone plan in standard mode. . In various embodiments, the additional zero tone is greater than or equal to 128, for example, with a tone spacing that is reduced by one-half of the FFT size, or of a tone that has a reduced FFT size by one-fourth. It is specified that only a predetermined FFT and / or tone spacing is exceeded if it is greater than or equal to 256 having a spacing. In some embodiments, an increased number of guard tones to maintain the same absolute guard spacing (eg, absolute frequency spacing) at the edge of the band compared to, for example, a standard mode legacy tone plan. Is used for non-legacy tone plans in distance extension mode. In this case, the total number of data tones and pilot tones in the non-legacy tone plan is smaller than in the legacy tone plan. In some examples, the same absolute guard spacing facilitates filter design. For example, in some embodiments where the total number of data tones in a non-legacy tone plan differs from the same FFT size in standard mode, the PHY parameter for the FEC interleaver and / or LDPC tone mapper is the number of data tones in the non-legacy tone plan. Redefined for numbers.

  FIG. 26A is a diagram of a distance extension mode non-legacy tone plan 2600 with a size 64 FFT and a 1/2 tone spacing, according to one embodiment. Compared to the standard mode legacy tone plan, the non-legacy tone plan 2600 includes additional guard tones (ie, guard tones -28, -27, +27, +28). In some embodiments, a 64-point FFT populates the DC tone with a pilot tone or data tone. FIG. 26B is a diagram of a distance extension mode non-legacy tone plan 2601 with a size 128 FFT and a 1/2 tone spacing, according to one embodiment. Compared to the standard mode legacy tone plan, the non-legacy tone plan 2601 has an additional guard tone (ie, guard tone -58, -57, +57, +58) and an additional DC tone (ie, DC tone -2, -1, 0, 1, 2). FIG. 26C is a diagram illustrating a distance extension mode non-legacy tone plan 2602 with a size 256 FFT and a 1/2 tone spacing, according to one embodiment. Compared to the standard mode legacy tone plan, the non-legacy tone plan 2602 includes additional guard tones (ie, guard tones -122, -121, +121, +122) and additional DC tones (ie, DC tone -2, -1, 0, 1, 2). In other embodiments, compared to the standard mode, in the distance extension mode, additional guard tones and / or DC tones are added to the non-legacy tone plan.

  FIG. 27 is a flow diagram of an exemplary method 2700 for generating data units according to one embodiment. Referring to FIG. 1, method 2700 is implemented by network interface 16 in one embodiment. For example, in one such embodiment, the PHY processing unit 20 is configured to implement the method 2700. According to another embodiment, the MAC process 18 is configured to implement at least a portion of the method 2700. With continued reference to FIG. 1, in yet another embodiment, the method 2700 is implemented by the network interface 27 (eg, the PHY processing unit 29 and / or the MAC processing unit 28). In other embodiments, the method 2700 is implemented with several other suitable network interfaces.

  At block 2702, a first OFDM symbol for the data field is generated. In various embodiments, generating an OFDM symbol at block 2702 may include OFDM symbols of the data portion according to one of a distance extension encoding scheme corresponding to the distance extension mode or a standard encoding scheme corresponding to the standard mode. Generating a step. In one embodiment, the distance extension encoding scheme includes the distance extension encoding scheme described above with respect to FIGS. 10A, 10B (eg, reduced tone spacing). In another embodiment, the distance extension encoding scheme includes the distance extension encoding scheme described above with respect to FIGS. 17A-20D (eg, bit-style repetition or symbol repetition). In yet another embodiment, the distance extension encoding scheme includes the distance extension encoding scheme described above with respect to FIGS. 22A-22C (eg, repetition of data units). In yet another embodiment, the distance extension encoding scheme includes a suitable combination of the distance extension encoding schemes described above with respect to FIGS. 10A, 10B, 17A-20D, and 22A-22C.

  In one embodiment, generating an OFDM symbol for a data portion of a PHY data unit according to a distance extension coding scheme includes using a forward error correction (FEC) encoder (eg, FEC encoder 1706, 1806 or 1906) to generate a plurality of information. Encoding the bits to obtain a plurality of encoded bits; for example, mapping the plurality of encoded bits to a plurality of constellation symbols using, for example, constellation mapper 1614 or 1914; for example, IDFT 1618 or 1818 is used to generate an OFDM symbol including a plurality of constellation symbols. In one embodiment, generating an OFDM symbol comprises: i) encoding a plurality of information bits according to a block coding scheme (eg, using block coder 1704); ii) a block (eg, using block coder 1808) Encoding a plurality of encoded bits according to an encoding scheme, or iii) performing one of the steps of encoding a plurality of constellation symbols according to a block encoding scheme (eg, using block coder 1916). It has further. In another embodiment, generating an OFDM symbol for the data field includes a plurality of constellation symbols in a first bandwidth portion of the channel bandwidth, eg, as described above with respect to FIGS. 22A-22C, and a channel. Generating an OFDM symbol for a data field including a plurality of copies of the constellation symbols in a second bandwidth portion of the bandwidth. In a further embodiment, copies of the plurality of constellation symbols are generated to include a predetermined phase shift.

  At block 2704, a data unit preamble is generated. The preamble generated at block 2704 is generated to indicate whether at least the data portion of the data unit generated at block 2702 has been generated using a distance extension encoding scheme or a standard encoding scheme. In various embodiments and / or scenarios, one of preambles 701 (FIGS. 9A, 10A), 751 (FIGS. 9B, 10B), 1101 (FIG. 11A), 1151 (FIG. 11B), or 1401 (FIG. 14A). One is generated at block 1604. In other embodiments, other suitable preambles are generated at block 2704.

  In one embodiment, the preamble indicates i) a first part indicating the duration of the PHY data unit and ii) whether at least some OFDM symbols of the data part are generated according to a distance extension coding scheme. Generated to have a second part. In a further embodiment, the first portion of the preamble is a first communication protocol (e.g., the first portion of the preamble determines the duration of the PHY data unit based on the first portion of the preamble). Formatted to be decodable by a receiver device that does not comply with the HEW communication protocol but conforms to the second communication protocol (eg, legacy communication protocol).

  In one embodiment, the preamble generated at block 2704 includes a CI indication set to indicate at least the data portion is being generated using a distance extension encoding scheme or a standard encoding scheme. In one embodiment, the CI indication includes 1 bit. In one embodiment, a portion of the preamble is generated in addition to the data portion using the encoding scheme indicated by the CI indication. In another embodiment, the preamble generated at block 2704 is such that the receiving device can automatically detect whether the preamble corresponds to a standard mode preamble or a distance extension mode preamble (eg, without decoding). Formatted. In one embodiment, detecting a distance extension mode preamble signals a receiving device that at least a data portion is generated using a distance extension encoding scheme.

  In one embodiment, generating the preamble comprises: i) a short training field compliant with the first communication protocol; and ii) a second portion of the preamble including a second OFDM symbol for at least one copy of the short training field. And i) generating a third OFDM symbol for at least one copy of the long training field and ii) a long training field compliant with the first communication protocol. In a further embodiment, the OFDM symbol, the second OFDM symbol, and the third OFDM symbol of the data portion have the same tone plan that is separate from the tone plan for the first portion of the preamble.

  In another embodiment, block 2704 generates a first signal field of the PHY data unit according to a second communication protocol (eg, legacy communication protocol), and at least some OFDM symbols of the data field extend the distance. Generating a second signal field as a copy of the first signal field to indicate that it is generated according to the mode. In a further embodiment, the first signal field and the second signal field indicate that the duration of the PHY data unit is a predetermined duration, and the second signal field is a first communication protocol. Can be used as a supplemental training field by receiver devices that comply with. In another embodiment, the first signal field and the second signal field are receivers compliant with the first communication protocol so as to increase the reliability of the decoding of the first signal field and the second signal field. It can be decoded in combination with the device.

  In one embodiment, the first portion of the preamble includes i) a legacy short training field that conforms to the second communication protocol, ii) a non-legacy long training field, and iii) a legacy signal that conforms to the second communication protocol. And the second part of the preamble does not include the training field. In the present embodiment, the first plurality of constellation symbols are generated for the legacy short training field using a legacy tone plan compliant with the second communication protocol, and the second plurality of constellation symbols are: An OFDM symbol generated for a non-legacy long training field using a non-legacy tone plan and a data field includes a third plurality of constellation symbols generated using a non-legacy tone plan.

  In one embodiment, a plurality of OFDM symbols are generated for a first portion of a preamble as a legacy preamble using a normal guard interval that conforms to a second communication protocol, and the plurality of OFDM symbols are long guards. Generated for the second part of the preamble using the interval. In a further embodiment, the non-legacy short training field of the OFDM symbol for the non-legacy signal field and the second part of the preamble is generated using a normal guard interval, and the OFDM symbol of the second part of the preamble is a long guard Generated for non-legacy long training fields using intervals. In another embodiment, the OFDM symbol is generated for the legacy signal field of the first portion of the preamble using the normal guard interval, and the OFDM symbol is not used for the second portion of the preamble using the long guard interval. Generated for legacy signal fields. In one embodiment, the second portion of the preamble is decodable by a plurality of receiver devices that conform to the first communication protocol, and the long guard interval of the second preamble is a plurality that conforms to the first communication protocol. To the receiver device that the PHY data unit complies with distance extension mode. In yet another embodiment, the plurality of OFDM symbols may include a second guard preamble using a long guard interval for i) a non-legacy signal field and ii) a copy of the first OFDM symbol for the non-legacy signal field. Are generated for In one embodiment, the plurality of OFDM symbols includes i) a double guard interval, ii) a first OFDM symbol for the field, and iii) a second OFDM symbol for the field that is a copy of the first OFDM symbol. Generated for each field of the plurality of fields in the second part of the preamble.

  At block 2706, a data unit is generated to include the preamble generated at block 2704 and the data portion generated at block 2702. In one embodiment, the PHY data unit includes a double guard interval followed by a first portion of the signal field and a second portion of the signal field according to a second communication protocol, It is generated so as not to include a guard interval with the signal field.

  In some embodiments, at least a first portion of the preamble is transmitted using a transmit power boost compared to the data field to increase the decoding range of the first portion of the preamble.

  In another embodiment, a first tone spacing and a long guard interval are used to generate a plurality of OFDM symbols for the data field, i) a second tone spacing different from the first tone spacing and ii A plurality of OFDM symbols for the first part of the preamble are generated using the standard guard interval. In a further embodiment, the second tone spacing in the first portion of the preamble is i) a legacy tone spacing that conforms to the second communication protocol, and ii) the first tone spacing of the data field. It is an integer multiple, and the standard guard interval is a legacy guard interval that conforms to the second communication protocol. In another embodiment, a preamble comprising: i) at least a first OFDM symbol using a legacy tone spacing and a legacy guard interval; and ii) at least a second OFDM symbol using a first tone spacing and a long guard interval. Multiple OFDM symbols for the second part are generated. In yet another embodiment, the plurality of OFDM symbols for the data field uses the first tone spacing and the plurality of constellation symbols in the first bandwidth portion of the channel bandwidth and the channel bandwidth first. And a plurality of constellation symbol copies in the two bandwidth portions, wherein the first bandwidth portion and the second bandwidth portion have the same bandwidth. In a further embodiment, generating the OFDM symbol for the data field comprises generating a plurality of constellation symbol copies to include a predetermined phase shift.

  In one embodiment, generating an OFDM symbol for a data field comprises generating an OFDM symbol for the data field using a first tone interval, a long guard interval, and a long symbol duration. In a further embodiment, generating an OFDM symbol for the first portion of the preamble includes generating an OFDM symbol for the first portion of the preamble using a second tone interval, a standard guard interval, and a duration of the standard symbol. Generating. In a further embodiment, the second tone spacing in the first part of the preamble is an integer multiple of i) the legacy tone spacing and ii) the first tone spacing in the data field, and the standard guard interval is Legacy guard interval, and the duration of the long symbol is a multiple of an integer n of the duration of the standard symbol.

  In another embodiment, generating a plurality of OFDM symbols for a data field of a PHY data unit according to a distance extension mode includes using a non-legacy tone spacing and a non-legacy tone plan that are not compliant with the second communication protocol. Generating a plurality of OFDM symbols for the preamble, the preamble generating step using a second tone spacing different from the non-legacy tone spacing and a legacy tone plan different from the non-legacy tone plan Generating a plurality of OFDM symbols for the first part of the. In a further embodiment, the non-legacy tone plan includes at least one guard tone instead of the corresponding data tone of the legacy tone plan that approximates the DC tone. In one embodiment, the non-legacy tone plan includes at least one data tone in place of the corresponding guard tone of the legacy tone plan so that the non-legacy tone plan and the legacy tone plan have the same number of data tones. In another embodiment, the non-legacy tone plan includes fewer data tones than the legacy tone plan, and using the non-legacy tone spacing and the non-legacy tone plan, generating multiple OFDM symbols for the data field comprises: And encoding a plurality of information bits of the plurality of OFDM symbols using an error correction code based on the number of data tones of the non-legacy tone plan. In one embodiment, the error correction code is a binary convolutional code. In another embodiment, the error correction code is a low density parity check code.

  FIG. 28 is a flow diagram of an exemplary method 2800 for generating a data unit, according to one embodiment. Referring to FIG. 1, method 2800 is implemented by network interface 16 in one embodiment. For example, in one such embodiment, the PHY processing unit 20 is configured to implement the method 2800. In addition, according to another embodiment, the MAC process 18 is configured to implement at least a portion of the method 2800. With continued reference to FIG. 1, in yet another embodiment, method 2800 is implemented by network interface 27 (eg, PHY processing unit 29 and / or MAC processing unit 28). In other embodiments, the method 2800 is implemented by several other suitable network interfaces.

  At block 2802, a first plurality of orthogonal frequency division multiplexed (OFDM) symbols is generated for a first field of a preamble to be included in a PHY data unit in one embodiment. In some embodiments, each OFDM symbol of the first plurality of OFDM symbols is obtained by multiplying at least a predetermined sequence with a second long training sequence of a second communication protocol. Corresponds to the first long training sequence of the communication protocol. At block 2804, in one embodiment, the first plurality of information bits for the second field of the preamble is encoded to generate a first plurality of encoded bits.

  At block 2806, in one embodiment, the first plurality of encoded bits is mapped to the first plurality of constellation symbols. At block 2808, in one embodiment, a first plurality of modified constellation symbols is generated that includes multiplying the first plurality of constellation symbols with a predetermined sequence. At block 2810, in one embodiment, a second plurality of orthogonal frequency division multiplexing (OFDM) symbols is generated that includes the first plurality of modified constellation symbols. At block 2812, in one embodiment, a preamble is generated that includes a first plurality of OFDM symbols for a first field and a second plurality of OFDM symbols for a second field. At block 2814, a PHY data unit that includes at least a preamble is generated.

  In some embodiments, the first plurality of information bits includes a first set of one or more information bits that indicate a duration of the PHY data unit, and the preamble is a PHY data unit based on the preamble. To be decodable by a receiver device that conforms to the second communication protocol but does not conform to the first communication protocol. In one embodiment, the i th value of the first long training sequence corresponds to the i th value of the predetermined sequence multiplied by the i th value corresponding to the second long training sequence, and i is Is an index.

  In one embodiment, the length of the first long training sequence is greater than or equal to the sum of the number of data tones and the number of pilot tones in the OFDM symbol defined by the second communication protocol. In some embodiments, generating the first plurality of modified constellation symbols comprises multiplying the predetermined sequence with the plurality of pilot tone constellation symbols for the second communication protocol. In some embodiments, the plurality of values of the predetermined sequence corresponding to the plurality of pilot tone constellation symbols have a value of one. In one embodiment, the plurality of values in the predetermined sequence have a value of +1 or -1.

  In some embodiments, generating the first plurality of OFDM symbols includes: an autocorrelation output for a first field generated by a receiver that is compliant with the first communication protocol; i) the first communication protocol; The first plurality of modes, or ii) signaling the second mode of the first communication protocol to allow automatic detection of the first mode or the second mode by the receiver device. Generating an OFDM symbol. In one embodiment, the first field includes a first long training sequence. In another embodiment, the first field includes a second long training sequence.

  In one embodiment, the method 2800 encodes a second plurality of information bits for the data field of the PHY data unit to generate a second plurality of encoded bits, and the second plurality of encoded bits. Generating a second plurality of modified constellation symbols comprising mapping the generated bits to a second plurality of constellation symbols and multiplying a predetermined sequence with the second plurality of constellation symbols Generating a third plurality of orthogonal frequency division multiplex (OFDM) symbols including a second plurality of modified constellation symbols and generating a data field including the third plurality of OFDM symbols And the number of steps for generating the PHY data unit is small. Comprising the step of generating the PHY data unit to also include a preamble and a data field.

  FIG. 29 is a diagram comparing an exemplary PHY preamble portion 2900 compliant with the HEW communication protocol with a preamble portion 2904 compliant with the legacy protocol, according to one embodiment. In one embodiment, the network interface device 16 of the AP 14 is configured to generate a data unit that includes a PHY preamble 2900 and send it to the client station 25-1 via orthogonal frequency division multiplexing (OFDM) modulation according to one embodiment. The In one embodiment, the network interface device 27 of the client station 25-1 uses a plurality of techniques discussed below to determine that the data unit that includes the preamble 2900 is compliant with the first communication protocol. Configured.

  Also, in one embodiment, the network interface device 27 of the client station 25-1 is configured to generate a data unit that includes the PHY preamble 2900 and send it to the AP. In one embodiment, the network interface device 16 of the AP 14 is configured to determine that the data unit including the preamble 2900 is compliant with the first communication protocol using a plurality of techniques discussed below. .

  According to one embodiment, the data unit including the PHY preamble 2900 conforms to the first communication protocol and occupies a 20 MHz bandwidth. A plurality of data units that conform to the first communication protocol and that include a preamble similar to the preamble 2900 may be other suitable bandwidths such as 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz in various other embodiments, or Multiple other suitable bandwidths may be occupied. Preamble 2900 is suitable in a “mixed mode” situation, that is, when WLAN 10 includes a client station (eg, legacy client station 25-4) that conforms to the legacy communication protocol but does not conform to the first communication protocol. . In some embodiments, the preamble 2900 is also used in a number of other situations.

  Preamble portion 2900 includes L-LTF 204/304/504. In one embodiment, L-LTF 204/304/504 includes a double guard interval 2908, a first L-LTF OFDM symbol 2912, and a second L-LTF OFDM symbol 2916. According to one embodiment, preamble portion 2900 further includes L-SIG 206/306/506, which include guard interval 2920 and L-SIG OFDM symbol 2924. According to one embodiment, the L-LTF 204/304/504 and the L-SIG 206/306/506 are associated with the legacy preamble 2904 (eg, IEEE 802.11a standard, IEEE 802.11g standard, IEEE 802.11n standard, and / or IEEE 802. Is a part of the first part of the preamble 2900 that matches the corresponding first part of the 11ac standard). The legacy device can decode the L-SIG 206/306/506 to determine the length of the PHY data unit that includes the PHY preamble 2900. In one embodiment, for example, L-SIG 206/306/506 includes a length field set to a value indicating the length of the PHY data unit that includes the PHY preamble 2900.

  Preamble 2900 includes a secondary L-SIG field 2928. In one embodiment, L-SIG field 2928 is a duplicate of L-SIG field 206/306/506. In one embodiment, a communication device configured to operate in accordance with the first communication protocol detects a repetition of the L-SIG field 206/306/506 in the preamble 2900, and the L-SIG field 206/306 Based on the detection of reception of / 506, the preamble 2900 is configured to be compliant with the first communication protocol. In one embodiment, upon detecting repetition of L-SIG fields 206/306/506, 2928, the receiving device uses the duplicates in multiple repeating L-SIG fields as additional training information, and in one embodiment channel estimation. To improve. In some embodiments, the receiving device first decodes L-SIG 206/306/506 and then uses the value of the length subfield in L-SIG 206/306/506 to 506, 2928 iterations are detected. In another embodiment, the receiving device first detects the repetition of the L-SIG fields 206/306/506, 2928, and then combines the detected multiple L-SIG fields 206/306/506, 2928 to L -Improve decoding reliability of the SIG fields 206/306/506, 2928 and / or improve channel estimation using redundant information in the multiple L-SIG fields 206/306/506, 2928;

  In one embodiment, preamble 2900 further includes a HEW-SIG1 field 2932, which includes a DGI 2936 and an OFDM symbol 2940 in the HEW-SIG1 field. Preamble 2900 also includes a secondary HEW-SIG1 field 2944. In one embodiment, HEW-SIG1 field 2944 is a duplicate of HEW-SIG1 field 2932. In one embodiment, a receiving device that conforms to the first communication protocol uses the duplicates in the repeating HEW-SIG1 fields 2932, 2944 as additional training information to improve channel estimation in one embodiment. In another embodiment, a receiving device compliant with the first communication protocol combines a plurality of detected HEW-SIG1 fields 2932, 2944 to improve decoding reliability of the HEW-SIG1 fields 2932, 2944. And / or use redundant information in multiple HEW-SIG1 fields 2932, 2944 to improve channel estimation.

  In one embodiment, the preamble portion 2900 can be determined by a receiving device configured in accordance with the first communication protocol that the data unit that includes the preamble 2900 is in compliance with the first communication protocol. Is formatted as follows. For example, in one embodiment, the LTF field 204/304/504 corresponds to the modified LTF field 2304 of FIG. 23, and in one embodiment, the first legacy signal field 206/306/506 is modified in FIG. Corresponding to the legacy signal field 2306 generated. In this embodiment, a receiving device that receives a data unit that includes the preamble 2900 is a first cross-correlation of LTF 204/304/504 that uses a long training sequence of a legacy communication protocol as described above in FIG. 23 in one embodiment. And detecting that the data unit conforms to the first communication protocol by performing a second cross-correlation of the LTF field 204/304/504 using the modified long training sequence of the first communication protocol Can do.

  In one embodiment, the preamble portion 3201 of the data unit 3200 is further formatted so that the legacy communication device can determine that the data unit 3200 is not compliant with the legacy communication protocol. For example, in one embodiment, the first L-SIG field 3202, the second L-SIG field 3204, and the HEW-SIG1 field 3208 each correspond to a receiving device in a plurality of OFDM symbols in the format 3220 of the legacy data unit. Modulated to detect BPSK modulation at location. For example, in one embodiment, upon detecting BPSK modulation in a plurality of OFDM symbols corresponding to the first L-SIG field 3202, the second L-SIG field 3204, and the HEW-SIG1 field 3206, the receiving device may The process of 3200 is stopped and the access to the medium is restrained for the duration determined based on the L-SIG field 3204.

  FIG. 30 is a diagram comparing an exemplary PHY preamble portion 3000 conforming to a first communication protocol with a preamble portion 2904 conforming to a legacy protocol, according to another embodiment. Preamble 3000 is similar to preamble 2900 of FIG. 29, and identically numbered elements are not discussed in detail for purposes of brevity. In one embodiment, the network interface device 16 of the AP 14 is configured to generate a data unit that includes the PHY preamble 3000 and send it to the client station 25-1 via OFDM modulation according to one embodiment. In one embodiment, the network interface device 27 of the client station 25-1 is configured to determine that the data unit that includes the preamble 3000 is compliant with a first communication protocol that uses a plurality of technologies discussed below. Is done.

  In one embodiment, the network interface device 27 of the client station 25-1 is also configured to generate and send a data unit including the PHY preamble 3000 to the AP 14. In one embodiment, the network interface device 16 of the AP 14 is configured to determine that the data unit including the preamble 3000 is compliant with the first communication protocol using a plurality of techniques discussed below. .

  According to one embodiment, the data unit including the PHY preamble 3000 is compliant with the first communication protocol and occupies a 20 MHz bandwidth. A plurality of data units conforming to the first communication protocol and including a preamble similar to the preamble 3000 may be other suitable bandwidths such as 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz in various other embodiments, or Multiple other suitable bandwidths may be occupied. The preamble 3000 is suitable in a “mixed mode” situation, that is, when the WLAN 10 includes a client station (eg, legacy client station 25-4) that conforms to the legacy communication protocol but does not conform to the first communication protocol. In some embodiments, the preamble 3000 is also used in a number of other situations.

  Unlike the preamble 2900, the preamble 3000 omits the secondary L-SIG 2928. Further, unlike the preamble 2900, the HEW-SIG1 3004 includes a GI 3008 instead of a DGI. The HEW-SIG1 3004 also includes a HEW-SIG1 OFDM symbol 3012. In one embodiment, HEW-SIG1 3016 is a replica of HEW-SIG1 3004. The preamble 3000 includes a HEW-SIG2 3020, and the HEW-SIG23020 includes a DGI 3024 and a HEW-SIG2 OFDM symbol 3028.

  According to one embodiment, the L-LTF 204/304/504 and the L-SIG 206/306/506 are associated with the legacy preamble 2904 (eg, IEEE 802.11a standard, IEEE 802.11g standard, IEEE 802.11n standard, and / or IEEE 802. Is a part of the first part of the preamble 3000 that matches the corresponding first part of the preamble according to the 11ac standard. The legacy device may decode the L-SIG 206/306/506 to determine the length of the PHY data unit that includes the PHY preamble 3000. In one embodiment, for example, L-SIG 206/306/506 includes a length field set to a value indicating the length of the PHY data unit that includes PHY preamble 3000.

  In one embodiment, a communication device configured to operate in accordance with the HEW protocol detects a repetition of the HEW-SIG1 field 3004, 3016 in the preamble 3000 and detects a repetition of the HEW-SIG1 field 3004, 3016. Is configured to determine that the preamble 3000 is compliant with the HEW communication protocol.

  In one embodiment, a receiving device that is compliant with the HEW protocol uses the duplicates in the repeating HEW-SIG1 fields 3004, 3016 as additional training information to improve channel estimation in one embodiment. In another embodiment, a receiving device that conforms to the HEW protocol combines a plurality of detected HEW-SIG1 fields 3004, 3016 to improve decoding reliability of the HEW-SIG1 fields 3004, 3016, and / or Alternatively, channel estimation is improved using redundant information in a plurality of HEW-SIG1 fields 3004, 3016.

  FIG. 31 is a diagram comparing an exemplary PHY preamble portion 3100 compliant with a first communication protocol with a preamble portion 2904 compliant with a legacy protocol according to another embodiment. Preamble 3100 is similar to preamble 2900 of FIG. 29 and preamble 3000 of FIG. 30, and identically numbered elements are not discussed in detail for the sake of brevity.

  In one embodiment, the network interface device 16 of the AP 14 is configured to generate a data unit that includes the PHY preamble 3100 and send it to the client station 25-1 via OFDM modulation according to one embodiment. In one embodiment, the network interface device 27 of the client station 25-1 is configured to determine that the data unit including the preamble 3100 is compliant with a first communication protocol using a plurality of technologies discussed below. Is done.

  In one embodiment, the network interface device 27 of the client station 25-1 is configured to generate a data unit including the PHY preamble 3100 and send it to the AP. In one embodiment, the network interface device 16 of the AP 14 is configured to determine that the data unit that includes the preamble 3100 is compliant with the first communication protocol using a plurality of techniques discussed below. .

  According to one embodiment, the data unit including the PHY preamble 3100 is compliant with the first communication protocol and occupies a 20 MHz bandwidth. A plurality of data units conforming to the first communication protocol and including a preamble similar to the preamble 3100 may be other suitable bandwidths such as 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz, etc. in various other embodiments, or Multiple other suitable bandwidths may be occupied. The preamble 3100 is suitable in a “mixed mode” situation, that is, when the WLAN 10 includes a client station (eg, a legacy client station 25-4) that conforms to the legacy communication protocol but does not conform to the first communication protocol. In some embodiments, the preamble 3100 is also used in a number of other situations.

  Unlike the preamble 2900, the HEW-SIG1 3004 includes a GI 3008 instead of a DGI. The HEW-SIG1 3004 also includes a HEW-SIG1 OFDM symbol 3012. In one embodiment, HEW-SIG1 3016 is a replica of HEW-SIG1 3004. The preamble 3100 includes a HEW-SIG2 3020, and the HEW-SIG23020 includes a DGI 3024 and a HEW-SIG2 OFDM symbol 3028.

  Unlike the preamble 3000, the preamble 3100 includes a secondary L-SIG field 2928. In one embodiment, L-SIG field 2928 is a duplicate of L-SIG field 206/306/506.

  According to one embodiment, the L-LTF 204/304/504 and the L-SIG 206/306/506 are associated with the legacy preamble 2904 (eg, IEEE 802.11a standard, IEEE 802.11g standard, IEEE 802.11n standard, and / or IEEE 802. Is a part of the first part of the preamble 3000 that matches the corresponding first part of the preamble according to the 11ac standard. The legacy device may decode the L-SIG 206/306/506 to determine the length of the PHY data unit that includes the PHY preamble 3000. In one embodiment, for example, L-SIG 206/306/506 includes a length field set to a value indicating the length of the PHY data unit that includes PHY preamble 3000.

  In one embodiment, a communication device configured to operate in accordance with the HEW protocol detects a repetition of the L-SIG field 206/306/506 in the preamble 2900 and the L-SIG field 206/306/506 Based on the detected iteration, the preamble 2900 is configured to determine compliance with the HEW communication protocol. In one embodiment, upon detecting repetition of L-SIG fields 206/306/506, 2928, the receiving device uses the duplicates in multiple repeating L-SIG fields as additional training information, and in one embodiment channel estimation. To improve. In some embodiments, the receiving device first decodes L-SIG 206/306/506 and then uses the value of the length subfield in L-SIG 206/306/506 to 506, 2928 iterations are detected. In another embodiment, the receiving device first detects the repetition of the L-SIG fields 206/306/506, 2928, and then combines the detected multiple L-SIG fields 206/306/506, 2928 to L -Improve decoding reliability of the SIG fields 206/306/506, 2928 and / or improve channel estimation using redundant information in the multiple L-SIG fields 206/306/506, 2928;

  In one embodiment, a communication device configured to operate in accordance with the HEW protocol detects a repetition of the HEW-SIG1 field 3004, 3016 in the preamble 3000 and detects a repetition of the HEW-SIG1 field 3004, 3016. Is configured to determine that the preamble 3000 is compliant with the HEW communication protocol.

  In one embodiment, a receiving device that is compliant with the HEW protocol uses the duplicates in the repeating HEW-SIG1 fields 3004, 3016 as additional training information to improve channel estimation in one embodiment. In another embodiment, a receiving device that conforms to the HEW protocol combines a plurality of detected HEW-SIG1 fields 3004, 3016 to improve decoding reliability of the HEW-SIG1 fields 3004, 3016, and / or Alternatively, channel estimation is improved using redundant information in a plurality of HEW-SIG1 fields 3004, 3016.

  FIG. 32 is a diagram of a portion of an OFDM data unit preamble 3200 that the network interface device 16 of the AP 14 is configured to generate with OFDM modulation and transmit to the client station 25-1 according to one embodiment. In one embodiment, the network interface device 27 of the client station 25-1 is configured to determine that the data unit that includes the preamble 3200 is compliant with a first communication protocol that uses a plurality of technologies discussed below. Is done.

  In one embodiment, the network interface device 27 of the client station 25-1 is configured to transmit a data unit including the preamble 3200 to the AP. In one embodiment, the network interface device 16 of the AP 14 is configured to determine that the data unit including the preamble 3200 is compliant with the first communication protocol using a plurality of techniques discussed below. .

  The data unit including the preamble 3200 conforms to the first communication protocol and occupies a 20 MHz bandwidth. In other embodiments, a plurality of data units conforming to the first communication protocol and having a plurality of preambles similar to the preamble 3200 may be other suitable bands such as 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz, etc. May occupy a width, or multiple other suitable bandwidths. The data unit that includes the preamble 3200 is in a “mixed mode” situation, that is, when the WLAN 10 includes a client station that conforms to the legacy communication protocol but does not conform to the first communication protocol (eg, the legacy client station 25-4). Is preferred. In some embodiments, the data unit that includes the preamble 3200 is also used in multiple other situations.

  The preamble 3200 includes a first long guard interval 3202-1, a long training field 3204 having a first portion 3204-1 and a second portion 320204-2, a second long guard interval 3202-2, a first L A SIG field 3206-1, a second L-SIG field 3206-2, a third long guard interval 3202-3, a first HEW signal field HEW-SIG1 3208, a fourth long guard interval 3202-4, and A preamble portion 3201 having a second HEW signal field HEW-SIG2 3210 is included. In one embodiment, the first L-SIG field 3206-1 corresponds to the L-SIG field 706 of the data unit 700 and the second L-SIG field 3206-2 is the first L-SIG field 3206. A duplicate of -1. In one embodiment, each long guard interval 3202 is a double guard interval that is twice as long as the standard guard interval defined by the legacy communication protocol. For example, in one embodiment, the standard guard interval defined by the legacy communication protocol is 0.8 μs, while the double guard interval is 1.6 μs. In another embodiment, each of the plurality of long guard intervals 3202 has another suitable value that is greater than the standard guard interval defined by the legacy communication protocol. For example, the standard guard interval specified by the legacy communication protocol is 0.8 μs, but in various embodiments, the long guard interval is greater than 1.2 μs, 2.4 μs, 3.2 μs, or 0.8 μs. Is a suitable value.

  With continued reference to FIG. 32, a legacy data unit format 3220 is shown for reference. Data units conforming to the format 3220 include a double guard interval 3222, a long training field 3224 having a first portion 3224-1 and a second portion 3224-2, a first standard guard interval 3225, and an L-SIG field. 3226, an OFDM symbol 3228 corresponding to a signal field (eg, HT-SIG1 field or VHT-SIG1 field), or an OFDM symbol of a data portion according to a specific legacy protocol corresponding to data unit 3200, and a third standard A guard interval 3225 and an OFDM symbol 3230 corresponding to a signal field (for example, HT-SIG2 field or VHT-SIG2 field), or a format 3200 Of including a OFDM symbol of the data portion corresponding to the legacy protocol.

  In one embodiment, the preamble portion 3201 of the data unit 3200 may allow a receiving device configured according to the first communication protocol to determine that the data unit 3200 is compatible with the first communication protocol. To be formatted. For example, in one embodiment, the L-LTF field 3204 corresponds to the modified LTF field 2304 of FIG. 23, and in one embodiment, the first legacy signal field 3206 corresponds to the modified legacy signal field 2306 of FIG. To do. In this embodiment, the receiving device that receives the data unit 3200 may receive a first cross-correlation and a first of the long training field 3202 using a long training sequence of a legacy communication protocol, as described above in FIG. 23 in one embodiment. By performing a second cross-correlation of the L-LTF field 3202 using a modified long training sequence of the communication protocol, it can be detected that the data unit 3200 is compliant with the first communication protocol. . Additionally or alternatively, a receiving device that receives the data unit 3200 in one embodiment detects the presence of the second L-SIG field 3205 in the preamble portion 3201, thereby causing the data unit 3200 to enter the first communication protocol. Compliance can be detected.

  In one embodiment, the preamble portion 3201 of the preamble 3200 is further formatted so that the legacy communication device can determine that the data unit that includes the preamble 3200 is not compliant with the legacy communication protocol. For example, in one embodiment, the first L-SIG field 3202, the second L-SIG field 3204, and the HEW-SIG1 field 3208 each correspond to a receiving device in a plurality of OFDM symbols in the format 3220 of the legacy data unit. Modulated to detect BPSK modulation at location. For example, in one embodiment, upon detecting BPSK modulation in a plurality of OFDM symbols corresponding to the first L-SIG field 3202, the second L-SIG field 3204, and the HEW-SIG1 field 3206, the receiving device may The process of 3200 is stopped and the access to the medium is restrained for the duration determined based on the L-SIG field 3204. As illustrated in FIG. 32, the first L-SIG field 3204 is the corresponding OFDM symbol in the legacy preamble 3220 in one embodiment because the long guard interval precedes the L-SIG field 3210 in the time domain. Not aligned with L-SIG3224. On the other hand, the second L-SIG field 3206-2 is aligned with the corresponding OFDM symbol 3228 in the legacy preamble 3220. In the illustrated embodiment, the HEW-SIG1 field is misaligned in the time domain with the corresponding OFDM symbol 3230 in the legacy preamble, similar to the first L-SIG field 3208.

  In one embodiment, the plurality of constellation points of the first L-SIG field 3206-1 and HEW-SIG1 field 3208 is a legacy communication using a plurality of corresponding OFDM symbols with a plurality of constellation points of legacy format 3220. Pre-rotated to appear as BPSK in the shifted FFT window used by the device. In one embodiment, the constellation points of the first L-SIG field 3206-1 and HEW-SIG1 field 3208 are rotated by an amount determined by the length of the long guard interval according to the duration of the long guard interval. The For example, in an embodiment where the long guard interval is twice as long as the standard guard interval defined by the legacy communication protocol, the constellations of each of the first L-SIG field 3206-1 and HEW-SIG1 field 3208 The point is rotated 90 ° as described above with respect to FIGS. 14B and 14C. As a result in the present embodiment, the first L-SIG field 3206-1 and HEW-SIG1 field 3208 are each modulated using inverted QBPSK (R-QPBPSK) modulation.

  In one embodiment, the second L-SIG field 3206-2 is aligned with the corresponding OFDM symbol 3228 in legacy format 3220, so that the second L-SIG field 3206-2 is modulated using BPSK modulation. Is done. In this embodiment, the cyclic prefix of the second L-SIG field 3206-2 does not match the last part of the first L-SIG field 3206-1 in one embodiment.

  FIG. 33 is a diagram of a portion 3300 of a preamble in an OFDM data unit configured for the network interface device 16 of the AP 14 to transmit to the client station 25-1 via OFDM modulation, according to one embodiment. In one embodiment, the network interface device 27 of the client station 25-1 is configured to determine that the data unit that includes the preamble 3300 is compliant with a first communication protocol that uses a plurality of technologies discussed below. Is done.

  In one embodiment, the network interface device 27 of the client station 25-1 is also configured to transmit a data unit including the preamble 3300 to the AP. In one embodiment, the network interface device 16 of the AP 14 is configured to determine that the data unit that includes the preamble 3300 is compliant with the first communication protocol using a plurality of techniques discussed below. .

  The data unit including the preamble 3300 conforms to the first communication protocol and occupies a 20 MHz bandwidth. In other embodiments, the plurality of data units conforming to the first communication protocol and having a plurality of preambles similar to the preamble 3300 may include other suitable bands such as 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz, etc. May occupy a width, or multiple other suitable bandwidths.

  In the preamble 3300, the second long guard interval 3202-2 is replaced by the standard guard interval 3302 in the preamble portion 3301 of the preamble 3300, and the second L-SIG field 3206-2 is omitted from the data unit 3300. Except for this, it is similar to the preamble 3200 of FIG. Further, the preamble portion 3301 includes a first HEW-SIG1 field 3208-1 and a second HEW-SIG1 field 3208-2 as compared to a single HEW-SIG1 field 3208 of the preamble 3200. In one embodiment, the second HEW-SIG1 field 3208-2 is a duplicate of the first HEW-SIG1 field 3208-1.

  In one embodiment, L-SIG field 3206 and second HEW-SIG1 field 3208-2 are each aligned with their corresponding OFDM symbols in legacy format 3220. On the other hand, the first HEW-SIG1 field 3208-1 is misaligned with its corresponding OFDM symbol in the legacy format 3220. In one embodiment, the constellation points of the first HEW-SIG field 3208-1 are pre-rotated so that the receiving device detects BPSK modulation in the shifted FFT window corresponding to the OFDM symbol 3228 ( For example, 90 °). In one embodiment, the second HEW-SIG1 field 3208-2 is modulated using BPSK modulation so that the receiving device can detect BPSK modulation of the corresponding OFDM symbol 3330 in legacy format 3200. However, in this case, in one embodiment, the second HEW-SIG1 field 3208-2 modulation (BPSK) is different from the first HEW-SIG1 field 3208-1 modulation (eg, R-QPBPSK). As a result, the cyclic prefix of the second HEW-SIG1 field 3208-2 does not exactly match the corresponding last part of the first HEW-SIG1 field 3208-1.

  Alternatively, in another embodiment, the second HEW-SIG1 field 3208-2 is modulated using the same modulation as the first HEW-SIG1 field 3208-1 (eg, R-QPBPSK). In the present embodiment, the cyclic prefix of the second signal field HEW-SIG1 field 3208-2 matches the last part of the first signal field HEW-SIG1 field 3208-1, and the HEW-SIG1 in the data unit 3300 Based on the detection of field repetition, it enables a non-legacy device to more accurately detect that the data unit that includes the preamble 3300 corresponds to the first communication protocol. Further, in this embodiment, the legacy device detects the modulation (eg, QPSK) shifted in the corresponding OFDM symbol 3230, thereby erroneously detecting the data unit 3200 as a data unit compliant with the IEEE-802-11ac standard. May bring. However, the legacy device interprets the second HEW-SIG1 field 3208-2 as a VHT-SIG2 field, and the CRC check of the VHT-SIG2 field fails. In one embodiment, the legacy device then discards the data unit with preamble 3300 in accordance with the IEEE 802.11ac standard and accesses the medium for the duration indicated in L-SIG field 3206 in one embodiment. Self-control. Based on the decoding of the second HEW-SIG1 field 3208-2, various methods for ensuring that legacy devices detect CRC errors are described in US patent application Ser. No. 13 filed Apr. 4, 2013. / 856,277 (Attorney Docket No. MP4709), which is incorporated herein by reference in its entirety.

  FIG. 34 is a diagram of a portion 3400 of a preamble in an OFDM data unit configured for the network interface device 16 of the AP 14 to transmit to the client station 25-1 via OFDM modulation, according to one embodiment. In one embodiment, the network interface device 27 of the client station 25-1 is configured to determine that the data unit including the preamble 3400 is compliant with a first communication protocol using a plurality of technologies discussed below. Is done.

  In one embodiment, the network interface device 27 of the client station 25-1 is also configured to transmit a data unit including the preamble 3400 to the AP. In one embodiment, the network interface device 16 of the AP 14 is configured to determine that the data unit including the preamble 3400 is compliant with the first communication protocol using a plurality of techniques discussed below. .

  The data unit including the preamble 3400 conforms to the first communication protocol and occupies a 20 MHz bandwidth. In other embodiments, the plurality of data units conforming to the first communication protocol and having a plurality of preambles similar to the preamble 3400 may include other suitable bands such as 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz, etc. May occupy a width, or multiple other suitable bandwidths.

  In one embodiment, the preamble 3400 includes a plurality of long guard intervals between the OFDM symbols of the preamble portion 3401 and does not include a duplicate of the L-SIG field 3206, except that the preamble portion 3401 of the preamble 3400 includes a plurality of long guard intervals. Similar to 32 preambles 3200. Further, in the illustrated embodiment, unlike the preamble 3200, the pre-rotation of the constellation points in the multiple OFDM symbols of the preamble 3400 is out of position with the corresponding OFDM symbol in the legacy format 3220.

  FIG. 35 is a diagram of a portion 3500 of a preamble in an OFDM data unit configured for the network interface device 16 of the AP 14 to transmit to the client station 25-1 via orthogonal frequency division multiplexing (OFDM) modulation, according to one embodiment. is there. In one embodiment, the network interface device 27 of the client station 25-1 is configured to determine that the data unit that includes the preamble 3500 is compliant with a first communication protocol that uses a plurality of technologies discussed below. Is done.

  In one embodiment, the network interface device 27 of the client station 25-1 is configured to transmit a data unit including the preamble 3500 to the AP 14. In one embodiment, the network interface device 16 of the AP 14 is configured to determine that the data unit that includes the preamble 3500 is compliant with the first communication protocol using a plurality of techniques discussed below. .

  The data unit including the preamble 3500 conforms to the first communication protocol and occupies a 20 MHz bandwidth. In other embodiments, the plurality of data units conforming to the first communication protocol and having a plurality of preambles similar to the preamble 3500 may be other suitable bands such as 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz, etc. May occupy a width, or multiple other suitable bandwidths. The preamble 3500 is the same as the preamble 3400 in FIG. 34 except that the second long guard interval 3302-2 is replaced by a standard guard interval 3502 in the preamble 3500. In this case, in one embodiment, L-SIG field 3206 is aligned with its corresponding OFDM symbol (L-SIG field 3226) in legacy format 3220.

  FIG. 36 is a diagram comparing an exemplary PHY preamble portion 3600 that conforms to a first communication protocol with a preamble portion 2904 that conforms to a legacy protocol, according to another embodiment. Preamble 3600 is similar to preamble 2900 of FIG. 29, and identically numbered elements are not discussed in detail for purposes of brevity.

  In one embodiment, the network interface device 16 of the AP 14 is configured to generate a data unit that includes the PHY preamble 3600 and send it to the client station 25-1 via OFDM modulation according to one embodiment. In one embodiment, the network interface device 27 of the client station 25-1 is configured to determine that the data unit that includes the preamble 3600 is compliant with a first communication protocol using a plurality of technologies discussed below. Is done.

  In one embodiment, the network interface device 27 of the client station 25-1 is also configured to generate a data unit that includes the PHY preamble 3600 and send it to the AP. In one embodiment, the network interface device 16 of the AP 14 is configured to determine that the data unit that includes the preamble 3600 is compliant with the first communication protocol using a plurality of techniques discussed below. .

  According to one embodiment, the data unit including the PHY preamble 3600 conforms to the first communication protocol and occupies a 20 MHz bandwidth. A plurality of data units conforming to the first communication protocol and including a preamble similar to the preamble 3600 may be other suitable bandwidths such as 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz in various other embodiments, or Multiple other suitable bandwidths may be occupied. The preamble 3600 is suitable in a “mixed mode” situation, that is, when the WLAN 10 includes a client station (eg, legacy client station 25-4) that conforms to the legacy communication protocol but does not conform to the first communication protocol. In some embodiments, the preamble 3600 is also used in a number of other situations.

  In one embodiment, the HEW-SIG field 3604 in the time domain is aligned with the corresponding OFDM symbol (V) HT-SIG1 field 3608 in the legacy preamble 2904 because the long guard interval 2936 precedes the HEW-SIG1 OFDM symbol 2940. Not.

  In one embodiment, the constellation points of the HEW-SIG1 OFDM symbol 2940 are rotated by an amount determined by the length of the long guard interval 2936 due to the duration of the long guard interval 2936. For example, in an embodiment where the long guard interval is twice as long as the standard guard interval defined by the legacy communication protocol, the constellation points of the HEW-SIG1 OFDM symbol 2940 are described above with respect to FIGS. 14B-14C. Is rotated 90 °. As a result, in one embodiment, the HEW-SIG1 field 3604 is modulated using inverted QBPSK (R-QPBPSK) modulation.

  FIG. 37 illustrates a portion 3700 of a preamble in an OFDM data unit configured to be generated and transmitted to the client station 25-1 by orthogonal frequency division multiplexing (OFDM) modulation by the network interface device 16 of the AP 14, according to one embodiment. FIG. In one embodiment, the network interface device 27 of the client station 25-1 is configured to determine that the data unit that includes the preamble 3700 is compliant with a first communication protocol that uses a plurality of technologies discussed below. Is done.

  Also, in one embodiment, the network interface device 27 of the client station 25-1 is configured to generate a data unit that includes the preamble 3700 and send it to the AP. In one embodiment, the network interface device 16 of the AP 14 is configured to determine that the data unit that includes the preamble 3700 is compliant with the first communication protocol using a plurality of techniques discussed below. .

  The data unit including the preamble 3700 conforms to the first communication protocol and occupies a 20 MHz bandwidth. In other embodiments, the plurality of data units that include a plurality of preambles that conform to the first communication protocol and are similar to the preamble 3700 may include other suitable bands such as 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz, etc. May occupy a width, or multiple other suitable bandwidths.

  The preamble 3700 is similar to the preamble 3300 of FIG. 33 except that the preamble 3700 omits the second (replicated) HEW-SIG1 field 3208-2 and includes an auto-detected OFDM symbol 3706. In one embodiment, the receiving device may detect that the data unit that includes the preamble 3700 conforms to the first communication protocol based on the detection of the auto-detected OFDM symbol 3706 in the data unit 3700. In the illustrated embodiment, the auto detect symbol 3706 immediately follows the L-SIG field 3206. In one embodiment, auto-detect symbol 3706 is aligned with its corresponding OFDM symbol in legacy data unit format 3220 and BPSK modulated for at least non-zero tones of the corresponding OFDM symbol in legacy format 3220 Is modulated using. In one embodiment, long guard interval 3710 is used with HEW-SIG1 field 3208 of preamble 3700. In one embodiment, the HEW-SIG1 field 3208 of the preamble 3700 is misaligned with the corresponding OFDM symbol in the legacy format 3220. In one embodiment, the constellation points of the HEW-SIG1 field 3208 are pre-rotated such that the legacy receiving device detects BPSK modulation using the FFT window of the corresponding OFDM symbol in legacy format 3220 (eg, 90 °).

  FIGS. 38A-38D are diagrams illustrating auto-detected OFDM symbols 3706 of a data unit 3700, according to some example embodiments. Referring first to FIG. 38A, in one embodiment, the auto-detected OFDM symbol 3706 includes five repetitions of an L-LTF sequence defined by multiple legacy communication protocols. In this embodiment, the non-legacy receiving device re-uses the start of the packet detection algorithm used to detect the start of the data unit 3700, based on the L-STF field included at the beginning of the data unit 3700, It can be detected that the data unit 3700 complies with the first communication protocol. Referring now to FIG. 38B, in one embodiment, the auto-detected OFDM symbol 3706 is a predetermined preference that is long (corresponding to more OFDM tones) compared to the L-STF sequence defined by the legacy communication protocol. Including two iterations of a simple sequence. For example, in one embodiment, the predetermined sequence includes an index in every other OFDM tone within each 20 MHz band of data unit 3700 (eg, set [+/− 2, + / 4, +/− 6, etc.]). A plurality of values corresponding to OFDM tones). Referring now to FIG. 38C, in one embodiment, the auto-detected OFDM symbol 3706 includes five repetitions of the last portion (eg, the last 0.8 μs) in the L-SIG field 3206. Referring now to FIG. 38C, in one embodiment, the auto-detect OFDM symbol 3706 includes two repetitions of a larger portion (eg, 1.6 μs) of the L-SIG field 3206, followed by the L-SIG field 3206. Followed by a postfix portion including a lower portion of a larger portion of (eg, 0.8 μs).

  In other embodiments, the auto-detect OFDM symbol 3706 may be used at a receiving device to detect any other pre-existing data unit that includes the preamble 3700 that is compliant with the first communication protocol. Contains a defined preferred sequence. For example, in various embodiments, the auto-detected OFDM symbol 3706 includes a predetermined Barker code sequence, a predetermined Golay code sequence, or other suitable predetermined sequence. In one embodiment, the receiving device detects that the data unit that includes the preamble 3700 complies with the first communication protocol by detecting a high correlation with a predetermined sequence of auto-detected OFDM symbols 3706.

  FIG. 39 is a diagram comparing an exemplary PHY preamble portion 3900 that conforms to a first communication protocol with a preamble portion 2904 that conforms to a legacy protocol, according to another embodiment. Preamble 3900 is similar to preamble 2900 of FIG. 29, and identically numbered elements are not discussed in detail for purposes of brevity.

  In one embodiment, the network interface device 16 of the AP 14 is configured to generate a data unit that includes the PHY preamble 3900 and send it to the client station 25-1 via OFDM modulation according to one embodiment. In one embodiment, the network interface device 27 of the client station 25-1 is configured to determine that the data unit that includes the preamble 3900 is compliant with a first communication protocol using a plurality of technologies discussed below. Is done.

  In one embodiment, the network interface device 27 of the client station 25-1 is also configured to generate a data unit that includes the PHY preamble 3900 and send it to the AP. In one embodiment, the network interface device 16 of the AP 14 is configured to determine that the data unit that includes the preamble 3900 is compliant with the first communication protocol using a plurality of techniques discussed below. .

  According to one embodiment, the data unit including the PHY preamble 3900 conforms to the first communication protocol and occupies a 20 MHz bandwidth. A plurality of data units conforming to the first communication protocol and including a preamble similar to the preamble 3900 may be other suitable bandwidths such as 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz in various other embodiments, or Multiple other suitable bandwidths may be occupied. The preamble 3900 is suitable in a “mixed mode” situation, that is, when the WLAN 10 includes a client station that conforms to the legacy communication protocol but does not conform to the first communication protocol (eg, the legacy client station 25-4). In some embodiments, the preamble 3900 is also used in a number of other situations.

  According to one embodiment, L-SIG206 / 36/506, L-SIG2928, and HEW-SIG1 2932 are modulated using BPSK, while HEW-SIG1 2944 is rotated BPSK (eg, Q-BPSK) Is modulated using.

  FIG. 40A is a diagram of a portion 4000 of another example PHY preamble that conforms to a first communication protocol, according to another embodiment.

  In one embodiment, the network interface device 16 of the AP 14 is configured to generate a data unit that includes the PHY preamble 4000 and send it to the client station 25-1 via OFDM modulation according to one embodiment. In one embodiment, the network interface device 27 of the client station 25-1 is configured to determine that the data unit that includes the preamble 4000 is compliant with a first communication protocol that uses a plurality of technologies discussed below. Is done.

  In one embodiment, the network interface device 27 of the client station 25-1 is also configured to generate a data unit that includes the PHY preamble 4000 and send it to the AP. In one embodiment, the network interface device 16 of the AP 14 is configured to determine that the data unit that includes the preamble 4000 is compliant with the first communication protocol using a plurality of techniques discussed below. .

  According to one embodiment, the data unit including the PHY preamble 4000 is compliant with the first communication protocol and occupies a 20 MHz bandwidth. A plurality of data units conforming to the first communication protocol and including a preamble similar to the preamble 4000 may be other suitable bandwidths such as 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz in various other embodiments, or Multiple other suitable bandwidths may be occupied. Preamble 4000 is suitable in a “mixed mode” situation, that is, when WLAN 10 includes a client station that conforms to the legacy communication protocol but does not conform to the first communication protocol (eg, legacy client station 25-4). In some embodiments, preamble 4000 is also used in a number of other situations.

  Preamble portion 4000 includes a legacy portion 4004 having a first L-LTF OFDM symbol 4008, a second L-LTF OFDM symbol 4012, and an L-SIG OFDM symbol 4016. In one embodiment, a double guard interval (not shown) is included before the L-LTF OFDM symbol 4008 and the guard interval is included between the L-LTF OFDM symbol 4012 and the L-SIG OFDM symbol 4016. It is. According to one embodiment, the legacy device can decode L-SIG 4016 to determine the length of the PHY data unit that includes the PHY preamble 4000. In one embodiment, for example, L-SIG 4016 includes a length field set to a value indicating the length of the PHY data unit that includes PHY preamble 4000.

  In one embodiment, the L-LTF field 4012 corresponds to the modified LTF field 2304 of FIG. 23, and in one embodiment, the L-SIG 4016 corresponds to the modified legacy signal field 2306 of FIG. In this embodiment, a receiving device that is compliant with the first communication protocol, in one embodiment, as described above with respect to FIG. 23, a first cross-correlation of L-LTF 4008 using a legacy communication protocol long training sequence and By performing the second cross-correlation of the L-LTF field 4012 using the modified long training sequence of the first communication protocol, the data unit including the preamble 4000 is compliant with the first communication protocol. Can be detected.

  The PHY preamble 4000 includes one or more HEW-STF OFDM symbols 4020, HEW-LTF1 OFDM symbols 4024, HEW-SIGA OFDM symbols 4028, one or more HEW-LTF OFDM symbols 4032, and HEW-SIGB OFDM symbols 4036. . In one embodiment, DGI is included between L-SIG 4016 and HEW-STF 4020a. In one embodiment, each DGI is between HEW-STF OFDM symbol 4020b and HEW-LTF1 OFDM symbol 4024, between HEW-LTF1 OFDM symbol 4024 and HEW-SIGA OFDM symbol 4028, and HEW-SIGA OFDM symbol 4028. It is included between one or more HEW-LTF OFDM symbols 4032 and between one or more HEW-LTF OFDM symbols 4032 and HEW-SIGB OFDM symbols 4036.

  FIG. 40B is a diagram of a portion 4050 of another example PHY preamble that conforms to the first communication protocol, according to another embodiment. Preamble portion 4050 is similar to preamble portion 4000, and identically numbered elements are not discussed in detail for purposes of brevity.

  In one embodiment, the network interface device 16 of the AP 14 is configured to generate a data unit that includes a PHY preamble 4050 and send it to the client station 25-1 via OFDM modulation according to one embodiment. In one embodiment, the network interface device 27 of the client station 25-1 is configured to determine that the data unit including the preamble 4050 is compliant with a first communication protocol using a plurality of technologies discussed below. Is done.

  In one embodiment, the network interface device 27 of the client station 25-1 is also configured to generate a data unit that includes the PHY preamble 4050 and send it to the AP. In one embodiment, the network interface device 16 of the AP 14 is configured to determine that the data unit that includes the preamble 4050 is compliant with the first communication protocol using a plurality of techniques discussed below. .

  According to one embodiment, the data unit including the PHY preamble 4050 is compliant with the first communication protocol and occupies a 20 MHz bandwidth. A plurality of data units conforming to the first communication protocol and including a preamble similar to the preamble 4050 may be other suitable bandwidths such as, for example, 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz in various other embodiments, or Multiple other suitable bandwidths may be occupied. Preamble 4050 is suitable in a “mixed mode” situation, that is, when WLAN 10 includes a client station that conforms to the legacy communication protocol but does not conform to the first communication protocol (eg, legacy client station 25-4). In some embodiments, the preamble 4050 is also used in a number of other situations.

  According to one embodiment, the legacy device can decode L-SIG 4016 to determine the length of the PHY data unit that includes the PHY preamble 4050. In one embodiment, for example, L-SIG 4016 includes a length field set to a value indicating the length of the PHY data unit that includes PHY preamble 4050.

  The preamble 4050 also includes one or more secondary L-SIGs 4054. In one embodiment, one or more secondary L-SIGs 4054 are replicas of L-SIG 4016.

  In one embodiment, the L-LTF field 4012 corresponds to the modified LTF field 2304 of FIG. 23, and in one embodiment, the L-SIG 4016 corresponds to the modified legacy signal field 2306 of FIG. In this embodiment, a receiving device that is compliant with the first communication protocol, in one embodiment, as described above with respect to FIG. 23, a first cross-correlation of L-LTF 4008 using a legacy communication protocol long training sequence and The data unit including the preamble 4050 is compliant with the first communication protocol by performing a second cross-correlation of the L-LTF field 4012 using the modified long training sequence of the first communication protocol. Can be detected.

  Additionally or alternatively, a receiving device that receives a data unit that includes a preamble 4050 in one embodiment detects the presence of one or more secondary L-SIG fields 4054 in the preamble portion 4050 so that the data unit is first It can be detected that the communication protocol is compliant.

  In one embodiment, DGI is included between L-SIG 4054b and HEW-STF 4020a. In one embodiment, each DGI is between HEW-STF OFDM symbol 4020b and HEW-LTF1 OFDM symbol 4024, between HEW-LTF1 OFDM symbol 4024 and HEW-SIGA OFDM symbol 4028, and HEW-SIGA OFDM symbol 4028. It is included between one or more HEW-LTF OFDM symbols 4032 and between one or more HEW-LTF OFDM symbols 4032 and HEW-SIGB OFDM symbols 4036.

  In some embodiments, the plurality of techniques as described above detects a plurality of data units that conform to the first communication protocol, and the plurality of data units are defined by the first communication protocol. It can be used to detect which of a plurality of modes corresponds. For example, FIG. 41 is a diagram comparing an exemplary PHY preamble portion 4100 compliant with a first communication protocol with a preamble portion 2904 compliant with a legacy protocol, according to another embodiment. Furthermore, the PHY preamble 4100 also supports the distance extension mode of the first communication protocol. FIG. 41 also includes a diagram comparing an exemplary PHY preamble portion 4104 compliant with the first communication protocol with a preamble portion 2904 compliant with the legacy protocol, according to another embodiment. Further, the PHY preamble 4104 corresponds to the standard mode of the first communication protocol.

  In one embodiment, the network interface device 16 of the AP 14 is configured to generate and transmit a data unit including the PHY preamble 4100 or PHY preamble 4104 to the client station 25-1 by OFDM modulation according to one embodiment. In one embodiment, the network interface device 27 of the client station 25-1 determines that the data unit that includes the preamble 4100 or preamble 4104 is compliant with a first communication protocol that uses a plurality of technologies discussed below. Configured as follows. In one embodiment, the network interface device 27 of the client station 25-1 uses a plurality of techniques discussed below to ensure that the data unit that includes the preamble 4100 conforms to the distance extension mode and the data unit that includes the preamble 4104 is Configured to determine compliance with standard mode.

  In one embodiment, the network interface device 27 of the client station 25-1 is also configured to generate and send a plurality of data units including the PHY preamble 4100 or PHY preamble 4104 to the AP 14. In one embodiment, the network interface device 16 of the AP 14 determines that the data unit including the PHY preamble 4100 or the PHY preamble 4104 is compliant with the first communication protocol using a plurality of techniques discussed below. Configured as follows. In one embodiment, the network interface device 16 of the AP 14 uses a plurality of techniques discussed below to allow the data unit including the preamble 4100 to comply with the distance extension mode and the data unit including the preamble 4104 to comply with the standard mode. Is configured to determine that

  According to one embodiment, the data unit including the PHY preamble 4100 conforms to the first communication protocol and occupies a 20 MHz bandwidth. A plurality of data units conforming to the first communication protocol and including a preamble similar to the preamble 4100 may be other suitable bandwidths such as 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz in various other embodiments, or Multiple other suitable bandwidths may be occupied. According to one embodiment, the data unit including the PHY preamble 4104 conforms to the first communication protocol and occupies a 20 MHz bandwidth. A plurality of data units that conform to the first communication protocol and include a preamble similar to the preamble 4104 may be other suitable bandwidths such as, for example, 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz in various other embodiments, or Multiple other suitable bandwidths may be occupied.

  Preamble 4100 is similar to preamble 2900 of FIG. 29, and identically numbered elements are not discussed in detail for purposes of brevity. The legacy device can decode L-SIG 206/306/506 to determine the length of the PHY data unit that includes the PHY preamble 4100. In one embodiment, for example, L-SIG 206/306/506 includes a length field set to a value indicating the length of the PHY data unit that includes PHY preamble 4100.

  In one embodiment, a communication device configured to operate in accordance with the HEW protocol detects a repetition of the L-SIG field 206/306/506 in the preamble 4100, and the L-SIG field 206/306/506 Based on the detected iteration, the preamble 4100 is configured to determine that it is compliant with the first communication protocol. Further, a communication device configured to operate in accordance with the first communication protocol may be configured such that the preamble 4100 is a distance of the first communication protocol based on the detected repetition of the L-SIG field 206/306/506. Configured to determine compliance with the extended mode.

  Preamble 4104 includes DGI 4104, L-LTF 4108, L-LTF 4112, GI 4116, and L-SIG 4120. In one embodiment, the L-LTF field 4112 corresponds to the modified LTF field 2304 of FIG. 23, and in one embodiment, the L-SIG 4120 corresponds to the modified legacy signal field 2306 of FIG. In this embodiment, a receiving device that is compliant with the first communication protocol, in one embodiment, as described above with respect to FIG. 23, the first cross-correlation of the L-LTF 4108 using the legacy communication protocol long training sequence and The data unit including the preamble 4104 is compliant with the first communication protocol by performing a second cross-correlation of the L-LTF field 4112 with the modified long training sequence of the first communication protocol. Can be detected. Similarly, a receiving device that conforms to the first communication protocol can detect that the data unit that includes the preamble 4104 conforms to the standard mode of the first communication protocol.

  In another embodiment, the L-LTF field 2916 corresponds to the modified LTF field 2304 of FIG. 23, and in one embodiment, the L-SIG 2924 corresponds to the modified legacy signal field 2306 of FIG. In this embodiment, a receiving device that is compliant with the HEW protocol, in one embodiment, as described above with respect to FIG. 23, the first cross-correlation of L-LTF 2912 using the long training sequence of the legacy communication protocol and the first Performing a second cross-correlation of the L-LTF field 2916 with a modified long training sequence of the communication protocol may detect that the data unit that includes the preamble 4100 is compliant with the HEW communication protocol. it can.

  FIG. 42 is a diagram comparing an exemplary PHY preamble portion 4200 compliant with a first communication protocol with a preamble portion 2904 compliant with a legacy protocol, according to another embodiment. Furthermore, the PHY preamble 4200 also supports the distance extension mode of the first communication protocol. FIG. 42 also includes a diagram comparing an exemplary PHY preamble portion 4204 compliant with a first communication protocol with a preamble portion 2904 compliant with a legacy protocol, according to another embodiment. Further, the PHY preamble 4204 corresponds to the standard mode of the first communication protocol.

  In one embodiment, the network interface device 16 of the AP 14 is configured to generate and transmit a data unit including the PHY preamble 4200 or PHY preamble 4204 to the client station 25-1 by OFDM modulation according to one embodiment. In one embodiment, the network interface device 27 of the client station 25-1 determines that the data unit including the preamble 4200 or the preamble 4204 is compliant with a first communication protocol using a plurality of technologies discussed below. Configured as follows. In one embodiment, the network interface device 27 of the client station 25-1 uses a plurality of techniques discussed below to ensure that the data unit including the preamble 4200 conforms to the distance extension mode and the data unit including the preamble 4204 is Configured to determine compliance with standard mode.

  In one embodiment, the network interface device 27 of the client station 25-1 is also configured to generate and send a plurality of data units including the PHY preamble 4200 or the PHY preamble 4204 to the AP. In one embodiment, the network interface device 16 of the AP 14 determines that the data unit including the PHY preamble 4200 or PHY preamble 4204 is compliant with the first communication protocol using a plurality of techniques discussed below. Configured as follows. In one embodiment, the network interface device 16 of the AP 14 uses a plurality of techniques discussed below, where the data unit that includes the preamble 4200 is compliant with the distance extension mode and the data unit that includes the preamble 4204 is in the standard mode. Configured to be compliant.

  According to one embodiment, the data unit including the PHY preamble 4200 is compliant with the first communication protocol and occupies a 20 MHz bandwidth. A plurality of data units conforming to the first communication protocol and including a preamble similar to the preamble 4200 may be other suitable bandwidths such as 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz in various other embodiments, or Multiple other suitable bandwidths may be occupied. According to one embodiment, the data unit including the PHY preamble 4204 conforms to the first communication protocol and occupies a 20 MHz bandwidth. A plurality of data units conforming to the first communication protocol and including a preamble similar to the preamble 4204 may be other suitable bandwidths such as 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz in various other embodiments, or Multiple other suitable bandwidths may be occupied.

  Preamble 4200 is similar to preamble 3000 of FIG. 30, and identically numbered elements are not discussed in detail for purposes of brevity. The legacy device may decode L-SIG 206/306/506 to determine the length of the PHY data unit that includes the PHY preamble 4200. In one embodiment, for example, L-SIG 206/306/506 includes a length field set to a value indicating the length of the PHY data unit that includes PHY preamble 4200.

  In one embodiment, a communication device configured to operate in accordance with the first communication protocol detects repetition of the HEW-SIG1 field 3004, 3016 in the preamble 4200, and detects the HEW-SIG1 field 3004, 3016. The preamble 4200 is configured to be compliant with the first communication protocol based on the repeated iterations. In addition, a communication device configured to operate in accordance with the first communication protocol may be configured such that the preamble 4200 is based on the detected repetition of the HEW-SIG1 fields 3004, 3016 and the distance extension mode of the first communication protocol. Configured to be compliant.

  Preamble 4204 is similar to preamble 4104 of FIG. 41, and identically numbered elements are not discussed in detail for purposes of brevity. In one embodiment, the L-LTF field 4112 corresponds to the modified LTF field 2304 of FIG. 23, and in one embodiment, the L-SIG 4120 corresponds to the modified legacy signal field 2306 of FIG. In this embodiment, a receiving device that is compliant with the first communication protocol, in one embodiment, as described above with respect to FIG. 23, the first cross-correlation of the L-LTF 4108 using the legacy communication protocol long training sequence and The data unit including the preamble 4104 is compliant with the first communication protocol by performing a second cross-correlation of the L-LTF field 4112 with the modified long training sequence of the first communication protocol. Can be detected. Similarly, a receiving device that conforms to the first communication protocol can detect that the data unit that includes the preamble 4104 conforms to the standard mode of the first communication protocol.

  In another embodiment, the L-LTF field 2916 corresponds to the modified LTF field 2304 of FIG. 23, and in one embodiment, the L-SIG 2924 corresponds to the modified legacy signal field 2306 of FIG. In this embodiment, a receiving device that is compliant with the first communication protocol, in one embodiment, as described above with respect to FIG. 23, a first cross-correlation of L-LTF 2912 using a legacy training protocol long training sequence and Performing a second cross-correlation of the L-LTF field 2916 using the modified long training sequence of the first communication protocol to detect that the data unit containing the preamble 4200 is compliant with the HEW communication protocol can do.

  FIG. 43 is a diagram comparing an exemplary PHY preamble portion 4300 that conforms to a first communication protocol with a preamble portion 2904 that conforms to a legacy protocol, according to another embodiment. Furthermore, the PHY preamble 4300 also supports the distance extension mode of the first communication protocol. FIG. 43 also includes a diagram comparing an exemplary PHY preamble portion 4304 compliant with the first communication protocol with a preamble portion 2904 compliant with the legacy protocol, according to another embodiment. Furthermore, the PHY preamble 4304 also supports the standard mode of the first communication protocol.

  In one embodiment, the network interface device 16 of the AP 14 is configured to generate and transmit data units including the PHY preamble 4300 or PHY preamble 4304 to the client station 25-1 by OFDM modulation according to one embodiment. In one embodiment, the network interface device 27 of the client station 25-1 determines that the data unit that includes the preamble 4300 or the preamble 4304 is compliant with a first communication protocol that uses multiple technologies discussed below. Configured as follows. In one embodiment, the network interface device 27 of the client station 25-1 uses a plurality of techniques discussed below to ensure that the data unit including the preamble 4300 conforms to the distance extension mode and the data unit including the preamble 4304 is Configured to determine compliance with standard mode.

  In one embodiment, the network interface device 27 of the client station 25-1 is also configured to generate and send a plurality of data units including the PHY preamble 4300 or PHY preamble 4304 to the AP 14. In one embodiment, the network interface device 16 of the AP 14 determines that the data unit including the PHY preamble 4300 or PHY preamble 4304 is compliant with the first communication protocol using a plurality of techniques discussed below. Configured as follows. In one embodiment, the network interface device 16 of the AP 14 uses a plurality of techniques discussed below, wherein the data unit including the preamble 4300 is compliant with the distance extension mode and the data unit including the preamble 4304 is in the standard mode. Configured to be compliant.

  According to one embodiment, the data unit including the PHY preamble 4300 conforms to the first communication protocol and occupies a 20 MHz bandwidth. A plurality of data units conforming to the first communication protocol and including a preamble similar to the preamble 4300 may be other suitable bandwidths such as 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz in various other embodiments, or Multiple other suitable bandwidths may be occupied. According to one embodiment, the data unit including the PHY preamble 4304 is compliant with the first communication protocol and occupies a 20 MHz bandwidth. A plurality of data units conforming to the first communication protocol and including a preamble similar to the preamble 4304 may be other suitable bandwidths such as 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz in various other embodiments, or Multiple other suitable bandwidths may be occupied.

  Preamble 4300 is similar to preamble 2900 of FIG. 29, and identically numbered elements are not discussed in detail for purposes of brevity. The legacy device may decode L-SIG 206/306/506 to determine the length of the PHY data unit that includes the PHY preamble 4300. In one embodiment, for example, the L-SIG 206/306/506 includes a length field set to a value indicating the length of the PHY data unit that includes the PHY preamble 4300.

  Data unit 4300 is similar to data unit 2900 of FIG. 29 except that data unit 4300 omits the second (replicated) L-SIG field 2928 and includes an auto-detected OFDM symbol 4308. In one embodiment, a receiving device that is compliant with the first communication protocol may determine that a data unit that includes the preamble 4300 is compliant with the first communication protocol based on detection of the auto-detected OFDM symbol 4308 in the preamble 4300. Can be detected. In the illustrated embodiment, the auto-detect symbol 4308 immediately follows the L-SIG field 206/306/506. In one embodiment, auto-detected symbol 4308 is aligned with its corresponding OFDM symbol in legacy data unit format 2904 and modulated using BPSK modulation. In one embodiment, a receiving device compliant with the first communication protocol has a data unit that includes a preamble 4300 based on detection of an auto-detected OFDM symbol 4308 in the preamble 4300 as discussed with respect to FIG. It is possible to detect compliance with a communication protocol.

  The preamble 4304 is similar to the preamble 4104 of FIG. 41, and identically numbered elements are not discussed in detail for the sake of brevity. In one embodiment, the L-LTF field 4112 corresponds to the modified LTF field 2304 of FIG. 23, and in one embodiment, the L-SIG 4120 corresponds to the modified legacy signal field 2306 of FIG. In this embodiment, a receiving device that is compliant with the first communication protocol, in one embodiment, as described above with respect to FIG. 23, the first cross-correlation of the L-LTF 4108 using the legacy communication protocol long training sequence and The data unit containing the preamble 4304 is compliant with the first communication protocol by performing a second cross-correlation of the L-LTF field 4112 with the modified long training sequence of the first communication protocol. Can be detected. Similarly, a receiving device compliant with the first communication protocol can detect that the data unit including the preamble 4304 is compliant with the standard mode of the first communication protocol.

  In another embodiment, the L-LTF field 2916 corresponds to the modified LTF field 2304 of FIG. 23, and in one embodiment, the L-SIG 2924 corresponds to the modified legacy signal field 2306 of FIG. In this embodiment, a receiving device that is compliant with the HEW protocol, in one embodiment, as described above with respect to FIG. 23, the first cross-correlation of L-LTF 2912 using the long training sequence of the legacy communication protocol and the first Performing a second cross-correlation of the L-LTF field 2916 with a modified long training sequence of the communication protocol detects that the data unit including the preamble 4300 is compliant with the first communication protocol be able to.

  In various other embodiments, the techniques described above with respect to FIGS. 9A-28 determine that a receiver that conforms to the first communication protocol i) the data unit conforms to the first communication protocol. Ii) used to allow to determine which of the various different modes of the first communication protocol (eg distance extension mode, standard mode, etc.) the data unit complies with, FIG. Combined with multiple techniques as described above for 40B.

式中、ＳＩＧ_ｋはＳＩＧ ＯＦＤＭシンボルのｋ番目のトーンであり、ｓ_ｋはＳＩＧ ＯＦＤＭシンボルにマッピングされるべきｋ番目のＢＰＳＫシンボルである。一実施形態において、第２の（複製）ＳＩＧ ＯＦＤＭシンボル上の複数のトーン（時間ｔ_２）は、次式に対応する。

式中、ＮはＳＩＧ ＯＦＤＭシンボルにおけるトーンの数である。従って一実施形態において、複数のＢＰＳＫシンボルｓは、第１のＳＩＧ ＯＦＤＭシンボルにおける複数のトーンにシーケンシャルにマッピングされるが、同一の複数のＢＰＳＫシンボルｓは、第２のＳＩＧ ＯＦＤＭシンボルにおける複数のトーンの半分にわたって周期的にシフトされる。複数の他の実施形態において、別の好適な時変トーンマッピングが複数の異なるＳＩＧ ＯＦＤＭシンボル全体にわたって時間ダイバーシチを実現するのに使用される。 In some embodiments where the SIG field is a replica (eg, L-SIG, HEW-SIG1, etc.), time-varying tone mapping is used. For example, in one embodiment, a cyclic shift tone mapper with a bandwidth of 1/2 is used. In one embodiment, the multiple tones (time t ₁ ) on the first SIG OFDM symbol correspond to:

Where SIG _k is the k th tone of the SIG OFDM symbol and s _k is the k th BPSK symbol to be mapped to the SIG OFDM symbol. In one embodiment, the multiple tones (time t ₂ ) on the second (replicated) SIG OFDM symbol correspond to:

Where N is the number of tones in the SIG OFDM symbol. Thus, in one embodiment, multiple BPSK symbols s are mapped sequentially to multiple tones in the first SIG OFDM symbol, but the same multiple BPSK symbols s are multiple tones in the second SIG OFDM symbol. Are periodically shifted over half of the. In other embodiments, another suitable time-varying tone mapping is used to achieve time diversity across multiple different SIG OFDM symbols.

  In one embodiment, time diversity across multiple different SIG OFDM symbols is implemented with different interleavers for the same multiple coded bits across two OFDM symbols. In other embodiments, other techniques suitable for implementing time diversity across multiple different SIG OFDM symbols are used.

式中、ｋはトーンインデックスである。一実施形態において、シーケンスｃ_ｋは±１の値を有するシーケンスである。 In some embodiments where the preamble conforms to the first communication protocol, the L-SIG field in the preamble conforming to the first communication protocol corresponds to the L-SIG in the legacy preamble multiplied by the sequence _ck .

Where k is the tone index. In one embodiment, the sequence _ck is a sequence having a value of ± 1.

  In some embodiments, one or more additional L-SIG fields are included in a plurality of preambles that conform to the first communication protocol.

  In some embodiments, the HEW-SIG field includes data unit duration information such as the number of bytes in the data unit, the number of OFDM symbols in the data unit.

  In some embodiments, a HEW-SIG field (eg, SIGA) that matches the SIG field in the legacy preamble is 100 for legacy devices (eg, IEEE 802.11ac receivers) by including a duplicate of the HEW-SIG field in the preamble. Is configured to generate SIGA CRC errors with a probability of%. For example, in various embodiments, multiple bits in the HEW-SIG field are scrambled to include a 1-bit field set to ensure that the SIGA CRC is in error. In another embodiment, the HEW-SIG field is designed to include multiple bits corresponding to multiple modes that are invalid in the legacy protocol.

  In one embodiment, the method generates a physical layer (PHY) data unit for transmission over a communication channel, the PHY data unit complying with a first communication protocol. The method comprises generating a PHY preamble for a PHY data unit at a first communication device, the step including generating a signal field to include a signal field and a duplicate of the signal field in the PHY preamble; The PHY preamble is formatted such that the first portion of the PHY preamble can be decoded by a second communication device that conforms to the communication protocol 2 but does not conform to the first communication protocol. Determining the duration of the PHY data unit based on the portion. The method also includes generating a PHY data unit to include a PHY preamble and a PHY payload at the first communication device.

  In various other embodiments, the method further includes one of two or more of the following features, or any suitable combination.

  The signal field is a legacy signal field that can be decoded by the second communication device, the legacy signal field is included in the first part of the PHY preamble, and the legacy signal field contains information indicating the duration of the PHY data unit. Including.

  Generating the PHY preamble for the PHY data unit further includes generating an additional signal field that conforms to the second communication protocol and including the additional signal field in the second portion of the PHY preamble.

  The second part of the PHY preamble is not decodable by the second communication device.

  Generating the PHY preamble for the PHY data unit further includes including a further signal field replica in the second portion of the PHY preamble.

  Generating the PHY preamble for the PHY data unit further includes including a further signal field replica in the second portion of the PHY preamble.

  The signal field is a first signal field, and generating the PHY preamble for the PHY data unit includes generating a second signal field decodable by the second communication device, and a first PHY preamble first. The method further includes including a second signal field in the portion and including a first signal field in the second portion of the PHY preamble, wherein the second signal field is information indicating a duration of the PHY data unit. including.

  The second part of the PHY preamble is not decodable by the second communication device.

  A PHY preamble for the PHY data unit is generated to include a respective first guard interval between a plurality of orthogonal frequency division (OFDM) symbols in a first portion of the PHY preamble, the method comprising: Generating a PHY payload to include a respective second guard interval between a plurality of OFDM symbols in the PHY payload, wherein each second guard interval is greater than each first guard interval. Also has a long duration.

  The PHY preamble for the PHY data unit is generated to include a respective second guard interval between the multiple OFDM symbols in the second portion of the PHY preamble.

  In another embodiment, the first communication device is compliant with the second communication protocol, generating a signal field, including a signal field and a duplicate of the signal field in a physical layer (PHY) preamble, The PHY preamble is formatted so that the first part of the PHY preamble can be decoded by a second communication device that does not conform to the first communication protocol, and the PHY data unit is based on the first part of the PHY preamble. A network interface device having one or more integrated circuits configured to generate a PHY preamble for a PHY data unit that conforms to a first communication protocol, including determining a duration. The one or more integrated circuits are also configured to generate a PHY data unit that includes a PHY preamble and a PHY payload.

  In various other embodiments, the first communication device further includes one of two or more of the following features, or any suitable combination.

  The signal field is a legacy signal field that is decodable by the second communication device, and the one or more integrated circuits are configured to include the legacy signal field in the first portion of the PHY preamble, Contains information indicating the duration of the PHY data unit.

  The one or more integrated circuits are configured to generate a further signal field that conforms to the second communication protocol and to include the further signal field in the second portion of the PHY preamble.

  The second part of the PHY preamble is not decodable by the second communication device.

  The one or more integrated circuits are configured to include additional signal field replicas in the second portion of the PHY preamble.

  The one or more integrated circuits are configured to include additional signal field replicas in the second portion of the PHY preamble.

  The signal field is a first signal field, and the one or more integrated circuits generate a second signal field that can be decoded by the second communication device, and the second signal in the first portion of the PHY preamble. The field is configured to include a first signal field in the second portion of the PHY preamble, the second signal field including information indicating a duration of the PHY data unit.

  The second part of the PHY preamble is not decodable by the second communication device.

  One or more integrated circuits generate a PHY preamble for a PHY data unit that includes a respective first guard interval between a plurality of orthogonal frequency division (OFDM) symbols in a first portion of the PHY preamble, and in the PHY payload It is configured to generate a PHY payload that includes a respective second guard interval between a plurality of OFDM symbols, each second guard interval having a longer duration than the first guard interval.

  The one or more integrated circuits are configured to generate the PHY preamble to include a respective second guard interval between the plurality of OFDM symbols in the second portion of the PHY preamble.

  At least some of the various blocks, operations, and techniques described above may be implemented using hardware, a processor that executes multiple firmware instructions, a processor that executes multiple software instructions, or any combination thereof. . When implemented using a processor that executes software or firmware instructions, the software or firmware instructions may be any non-transitory, tangible computer-readable medium, or magnetic disk, optical disk, random access memory (RAM), read It can be stored in a medium such as only memory (ROM), flash memory, or magnetic tape. Software or firmware instructions may include a plurality of machine readable instructions that, when executed by one or more processors, cause the one or more processors to perform various operations.

  When implemented in hardware, the hardware may comprise one or more of a plurality of discrete components, integrated circuits, application specific integrated circuits (ASICs), programmable logic devices (PLDs), and so on.

  Although the present invention has been described with reference to specific examples, these are only exemplary and are not intended to limit the invention and depart from the scope of the invention. Without limitation, multiple changes, additions and / or deletions can be made to the disclosed embodiments.

Claims (20)

A method of generating a physical layer (PHY) data unit conforming to a first communication protocol for transmission over a communication channel, comprising:
The method
Generating a PHY preamble for the PHY data unit in a first communication device;
The stage includes
Generating a signal field;
Including the signal field and a copy of the signal field in the PHY preamble;
Formatting the PHY preamble so that a first portion of the PHY preamble can be decoded by a second communication device that conforms to a second communication protocol but does not conform to the first communication protocol; Determining a duration of the PHY data unit based on the first portion of a PHY preamble;
Generating the PHY data unit at the first communication device to include the PHY preamble and a PHY payload. The signal field is a legacy signal field that can be decoded by the second communication device;
The legacy signal field is included in the first portion of the PHY preamble,
The method of claim 1, wherein the legacy signal field includes information indicating the duration of the PHY data unit. Generating the PHY preamble for the PHY data unit comprises:
Generating a further signal field conforming to the second communication protocol;
3. The method of claim 2, further comprising including the additional signal field in a second portion of the PHY preamble.   The method of claim 3, wherein the second portion of the PHY preamble is not decodable by the second communication device.   The method according to claim 3 or 4, wherein generating the PHY preamble for the PHY data unit further comprises including a copy of the further signal field in the second portion of the PHY preamble.   The method according to any one of the preceding claims, wherein generating the PHY preamble for the PHY data unit further comprises including a further signal field replica in a second part of the PHY preamble. . The signal field is a first signal field;
Generating the PHY preamble for the PHY data unit comprises:
Generating a second signal field decodable by the second communication device;
Including the second signal field in the first portion of the PHY preamble;
Including the first signal field in a second portion of the PHY preamble;
The method according to claim 1, wherein the second signal field includes information indicating the duration of the PHY data unit.   The method of claim 7, wherein the second portion of the PHY preamble is not decodable by the second communication device. The PHY preamble for the PHY data unit is generated to include a respective first guard interval between a plurality of orthogonal frequency division (OFDM) symbols in the first portion of the PHY preamble;
The method further comprises generating the PHY payload at the first communication device to include a respective second guard interval between a plurality of OFDM symbols in the PHY payload,
9. A method according to any one of the preceding claims, wherein each second guard interval has a longer duration than each first guard interval.   The method of claim 9, wherein the PHY preamble for the PHY data unit is generated to include a respective second guard interval between a plurality of OFDM symbols in a second portion of the PHY preamble. Generating a signal field; including the signal field and a copy of the signal field in a physical layer (PHY) preamble; and a second that is compliant with the second communication protocol but not compliant with the first communication protocol. Formatting the PHY preamble such that a first part of the PHY preamble can be decoded by a communication device and determining a duration of a PHY data unit based on the first part of the PHY preamble; Including
Generating the PHY preamble for the PHY data unit conforming to the first communication protocol;
A first communication device comprising a network interface device having one or more integrated circuits that generate the PHY data unit to include the PHY preamble and PHY payload. The signal field is a legacy signal field that can be decoded by the second communication device;
The one or more integrated circuits include the legacy signal field in the first portion of the PHY preamble;
The first communication device according to claim 11, wherein the legacy signal field includes information indicating the duration of the PHY data unit. The one or more integrated circuits are:
Generating a further signal field conforming to the second communication protocol;
13. The first communication device of claim 12, including the additional signal field in a second portion of the PHY preamble.   The first communication device of claim 13, wherein the second portion of the PHY preamble is not decodable by the second communication device.   15. The first communication device of claim 13 or 14, wherein the one or more integrated circuits include a copy of the additional signal field in the second portion of the PHY preamble.   16. The first communication device of any one of claims 11-15, wherein the one or more integrated circuits include a further signal field replica in a second portion of the PHY preamble. The signal field is a first signal field;
The one or more integrated circuits are:
Generating a second signal field decodable by the second communication device;
Including the second signal field in the first portion of the PHY preamble;
Including the first signal field in a second portion of the PHY preamble;
The first communication device according to any one of claims 11 to 16, wherein the second signal field includes information indicating the duration of the PHY data unit.   The first communication device of claim 17, wherein the second portion of the PHY preamble is not decodable by the second communication device. The one or more integrated circuits are:
Generating the PHY preamble for the PHY data unit to include a respective first guard interval between a plurality of orthogonal frequency division (OFDM) symbols in the first portion of the PHY preamble;
Generating the PHY payload to include a respective second guard interval between a plurality of OFDM symbols in the PHY payload;
The first communication device according to any one of claims 11 to 18, wherein each second guard interval has a duration that is longer than each first guard interval.   21. The first of claim 19, wherein the one or more integrated circuits generate the PHY preamble to include a respective second guard interval between a plurality of OFDM symbols in a second portion of the PHY preamble. 1 communication device.

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