KR102376949B1 - Physical layer frame format for wlan - Google Patents

Abstract

A method for generating a physical layer (PHY) data unit for transmission over a communication channel, the PHY data unit conforming to a first communication protocol, wherein the first communication device generates a PHY preamble for the PHY data unit, comprising: a signal field generating a signal field and including a replica of the signal field in the PHY preamble, and wherein the first portion of the PHY preamble communicates with the second communication to determine a duration of the PHY data unit based on the first portion of the PHY preamble. and formatting the PHY preamble to be decodable by a second communication device that conforms to the protocol but does not conform to the first communication protocol. The first communication device generates a PHY data unit including a PHY preamble and a PHY payload.

Description

Physical layer frame format for WLAN

REFERENCE TO RELATED APPLICATIONS

This disclosure is a continuation in part (CIP) of U.S. Patent Application Serial No. 14/523,678, entitled “Range Extension Mode for WiFi,” filed on October 24, 2014, and filed on October 25, 2013 US titled “Range Extension PHY”, filed in Provisional Patent Application No. 61/895,591, and U.S. Pat. Provisional Patent Application No. 61/925,332, and U.S. Pat. Provisional Patent Application No. 61/950,727, and U.S. Pat. Provisional Patent Application No. 61/987,778, the disclosures of which are incorporated herein by reference in their entirety.

Additionally, this disclosure is disclosed in U.S. Pat. Provisional Patent Application No. 61/924,467, U.S. Pat. Provisional Patent Application No. 62/030,426, U.S. Pat. Provisional Patent Application No. 62/034,509, U.S. Pat. Provisional Patent Application No. 62/045,363, U.S. Pat. Provisional Patent Application No. 62/051,537, and U.S. Pat. Provisional Patent Application No. 62/089,032, the disclosures of which are incorporated herein by reference in their entirety.

field of initiation

BACKGROUND OF THE INVENTION Field of the Invention [0001] The present invention relates generally to wireless communication networks, and more particularly, to physical layer (PHY) frame formats capable of coexistence with legacy devices in wireless local area networks.

When operating in an infrastructure mode, wireless local area networks (WLANs) typically include an access point (AP) and one or more client stations. WLANs have evolved rapidly over the past few decades. 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, has improved single-user peak data throughput. 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 specifies 600 Specifies single-user peak throughput in Mbps, and the IEEE 802.11ac standard specifies single-user peak throughput in the gigabits per second (Gbps) range. Future standards are likely to provide much greater throughputs, such as throughputs in the tens of Gbps range.

In one embodiment, a method for generating a physical layer (PHY) data unit for transmission over a communication channel, the PHY data unit conforming to a first communication protocol. The method comprises, in a first communication device, generating a PHY preamble for the PHY data unit, wherein generating the PHY preamble comprises generating a signal field, and adding the signal field and a copy of the signal field to the PHY preamble. and to determine a duration of the PHY data unit based on the first portion of the PHY preamble, wherein the first portion of the PHY preamble conforms to a second communication protocol, but does not conform to the first communication protocol. and formatting the PHY preamble to be decodable by a second communication device. The method also includes generating, at the first communication device, the PHY data unit including the PHY preamble and a PHY payload.

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

the signal field is a legacy signal field decodable by the second communication device; the legacy signal field is included in the first part of the PHY preamble; and the legacy signal field includes information indicating a duration of the PHY data unit.

Generating the PHY preamble for the PHY data unit further comprises generating an additional signal field conforming to the second communication protocol, and including the additional signal field in a second portion of the PHY preamble. .

The second portion of the PHY preamble is not decodable to the second communication device.

Generating the PHY preamble for the PHY data unit further comprises: including a copy of the additional signal field in a second portion of the PHY preamble.

Generating the PHY preamble for the PHY data unit further comprises: including a copy of the additional signal field in a second portion of the PHY preamble.

the signal field is a first signal field; and generating the PHY preamble for the PHY data unit comprises: generating a second signal field decodable by the second communication device, the second signal field indicating a duration of the PHY data unit. generating the second signal field comprising information; including the second signal field in a first portion of the PHY preamble; and including the first signal field in a second portion of the PHY preamble.

The second portion of the PHY preamble is not decodable to the second communication device.

the PHY preamble for the PHY data unit is generated by including a respective first guard interval between orthogonal frequency domain (OFDM) symbols in a first portion of the PHY preamble; and the method further comprises generating, at the first communication device, the PHY payload including a respective second guard interval between OFDM symbols in the PHY payload, wherein each second guard interval is It has a longer duration than each first guard interval.

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

In another embodiment, a first communication device comprises a network interface device having one or more integrated circuits, wherein the one or more integrated circuits: generate a physical layer (PHY) preamble for the PHY data unit conforming to a first communication protocol and generating the physical layer preamble comprises generating a signal field, including the signal field and a copy of the signal field in the PHY preamble, and the PHY data unit based on a first portion of the PHY preamble. and formatting the PHY preamble so that a first portion of the PHY preamble conforms to a second communication protocol, but is decodable by a second communication device that does not conform to the first communication protocol to determine the duration of the PHY preamble. The one or more integrated circuits are also configured to generate the PHY data unit including the PHY preamble and the PHY payload.

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

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

The one or more integrated circuits are configured to generate an additional signal field conforming to the second communication protocol, and include the additional signal field in the second portion of the PHY preamble.

The second portion of the PHY preamble is not decodable to the second communication device.

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

The one or more integrated circuits are configured to include a copy of the additional signal field 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 decodable by the second communication device, the second signal field comprising information indicating a duration of the PHY data unit, the first signal field of the PHY preamble including the second signal field in a portion; and include the first signal field in the second portion of the PHY preamble.

The second portion of the PHY preamble is not decodable to the second communication device.

the one or more integrated circuits include a respective first guard interval between orthogonal frequency domain (OFDM) symbols in a first portion of the PHY preamble to generate the PHY preamble for the PHY data unit; and generate the PHY payload including a respective second guard interval between OFDM symbols in the PHY payload, each second guard interval having a longer duration than each first guard interval. .

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

1 is a block diagram of an exemplary wireless local area network (WLAN), according to one embodiment.
2A and 2B are diagrams of a prior art data unit format.
3 is a diagram of another prior art data unit format.
4 is a diagram of another prior art data unit format.
5 is a diagram of another prior art data unit format.
6A is a group of modulation diagrams used to modulate symbols within a data unit of the prior art.
6B is a group of modulation diagrams used to modulate symbols in an exemplary data unit, according to an embodiment.
7A is a diagram of an orthogonal frequency division multiplexing (OFDM) data unit according to an embodiment.
7B is a group of modulation diagrams used to modulate symbols in the data unit depicted in FIG. 7A according to an embodiment.
8 is a block diagram of an OFDM symbol according to an embodiment.
9A is a diagram illustrating an example data unit in which a regular coding scheme is used for a preamble of the data unit according to an embodiment.
9B is a diagram illustrating an example data unit in which a canonical coding scheme is used for only a portion of the preamble of the data unit, according to an embodiment.
10A is a diagram illustrating an example data unit in which tone spacing adjustment is used in combination with block coding according to an embodiment.
10B is a diagram illustrating an example data unit in which tone spacing adjustment is used in combination with block coding according to another embodiment.
11A is a diagram illustrating a regular mode data unit according to an embodiment.
11B is a diagram illustrating a range extension mode data unit according to an embodiment.
12A-12B are diagrams separately illustrating two possible formats of a long training field according to two example embodiments.
FIG. 13A is a diagram illustrating a non-legacy signal field of the regular mode data unit of FIG. 11A according to an embodiment.
13B is a diagram illustrating a non-legacy signal field of the range extension mode data unit of FIG. 11B according to an embodiment.
14A is a diagram illustrating a range extension mode data unit according to an embodiment.
14B is a diagram illustrating a legacy signal field of the range extension mode data unit of FIG. 14A according to an embodiment.
14C is a diagram illustrating a fast Fourier transform (FFT) window for the legacy signal field of FIG. 14B at a legacy receiving device according to one embodiment;
15 is a block diagram illustrating the format of a non-legacy signal field according to an embodiment.
16 is a block diagram illustrating an example PHY processing unit for generating regular mode data units using a canonical coding technique according to an embodiment.
17A is a block diagram of an example PHY processing unit for generating range extension mode data units using a range extension coding technique according to an embodiment.
17B is a block diagram of an example PHY processing unit for generating range extension mode data units according to another embodiment.
18A is a block diagram of an example PHY processing unit for generating range extension mode data units using a range extension coding technique according to another embodiment.
18B is a block diagram of an example PHY processing unit for generating range extension mode data units according to another embodiment.
19A is a block diagram of an example PHY processing unit for generating range extension mode data units according to another embodiment.
19B is a block diagram of an example PHY processing unit for generating range extension mode data units according to another embodiment.
20A is a diagram illustrating repetition of OFDM symbols in a preamble of a range extension mode data unit according to an embodiment.
20B is a diagram illustrating repetition of OFDM symbols in a preamble of a range extension mode data unit according to an embodiment.
20C is a diagram illustrating a time domain repetition scheme for OFDM symbols according to an embodiment.
20D is a diagram illustrating a repetition scheme for OFDM symbols according to another embodiment.
21 is a flow diagram of an exemplary method for creating a data unit according to one embodiment.
22A is a diagram of a 20 MHz full bandwidth with repetitions of a range extension data unit with a 10 MHz subband according to one embodiment.
22B is a diagram of a 40 MHz full bandwidth with repetitions of a range extension data unit with a 10 MHz subband according to one embodiment.
22C is a diagram of an example tone plan for a 32-FFT mode according to one embodiment.
23 is a diagram of an example data unit in which a laser extension mode is used for a preamble of a data unit according to an embodiment.
24 is a block diagram of an example PHY processing unit for generating range extension mode data units according to another embodiment.
25A is a diagram of an example 20 MHz full bandwidth with ½ tone spacing according to one embodiment.
25B is a diagram of an example 20 MHz full bandwidth with ½ tone spacing according to one embodiment.
26A is a diagram of a non-legacy tone plan for range extension mode with size 64 FFT and ½ tone spacing, according to one embodiment.
26B is a diagram of a non-legacy tone plan for range extension mode with size 128 FFT and ½ tone spacing according to one embodiment.
26C is a diagram of a non-legacy tone plan for range extension mode with size 256 FFT and ½ tone spacing according to one embodiment.
27 is a flow diagram of an exemplary method for generating a data unit in accordance with one embodiment.
28 is a flow diagram of an exemplary method for generating a data unit according to another embodiment.
29 is a diagram of an example PHY preamble portion conforming to a first communication protocol, according to an embodiment, as compared to a preamble portion conforming to a legacy protocol;
30 is a diagram of another example PHY preamble portion conforming to a first communication protocol, according to another embodiment, as compared to a preamble portion conforming to a legacy protocol;
31 is a diagram of another example PHY preamble portion conforming to a first communication protocol, according to another embodiment, as compared to a preamble portion conforming to a legacy protocol;
32 is a diagram of another example PHY preamble portion conforming to a first communication protocol, according to another embodiment, as compared to a preamble portion conforming to a legacy protocol;
33 is a diagram of another example PHY preamble portion conforming to a first communication protocol, according to another embodiment, as compared to a preamble portion conforming to a legacy protocol;
34 is a diagram of another example PHY preamble portion conforming to a first communication protocol according to another embodiment as compared to a preamble portion conforming to a legacy protocol;
35 is a diagram of another example PHY preamble portion conforming to a first communication protocol, according to another embodiment, as compared to a preamble portion conforming to a legacy protocol;
36 is a diagram of another example PHY preamble portion conforming to a first communication protocol, according to another embodiment, as compared to a preamble portion conforming to a legacy protocol;
37 is a diagram of another example PHY preamble portion conforming to a first communication protocol, according to another embodiment, as compared to a preamble portion conforming to a legacy protocol;
38A-D are diagrams illustrating examples of auto detection symbols used with the example PHY preamble of FIG. 37 in accordance with various embodiments.
39 is a diagram of another example PHY preamble portion conforming to a first communication protocol according to another embodiment as compared to a preamble portion conforming to a legacy protocol;
40A is a diagram of another example PHY preamble portion conforming to a first communication protocol, according to another embodiment.
40B is a diagram of another example PHY preamble portion conforming to a first communication protocol, according to another embodiment.
41 is a diagram of another example PHY preamble portion conforming to a regular mode of a first communication protocol and another example PHY preamble portion conforming to a range extension mode of a first communication protocol as compared to a preamble portion conforming to a legacy protocol, according to an embodiment; is a diagram of
42 is a diagram of another example PHY preamble portion conforming to a regular mode of a first communication protocol and another example PHY preamble portion conforming to a range extension mode of a first communication protocol as compared to a preamble portion conforming to a legacy protocol, according to an embodiment; is a diagram of
43 is a diagram of another example PHY preamble portion conforming to a regular mode of a first communication protocol and another example PHY preamble portion conforming to a range extension mode of a first communication protocol as compared to a preamble portion conforming to a legacy protocol, according to an embodiment; is a diagram of

In the embodiments described below, a wireless network device, such as an access point (AP) of a wireless local area network (WLAN), transmits data streams to one or more client stations. The AP is configured to operate with the client stations according to at least a first communication protocol. The first communication protocol is sometimes referred to herein as “High Efficiency Wi-Fi,” “HEW” communication protocol, or 802.11ax communication protocol. In some embodiments, different client stations in the vicinity of the AP are configured to operate according to one or more other communication protocols that define operation in the same frequency band as the HEW communication protocol but with lower overall data throughputs. 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 generally deployed as indoor communication channels, and the HEW communication protocol at least occasionally provides for outdoor communication, extended range communication, or reduced signal-to-noise ratios (SNR) of transmitted signals. It is arranged for communication within the areas it has.

The symbols transmitted by the AP, according to one embodiment, are generated according to a range extension coding technique that provides for increased redundancy of symbols or encoded information bits within the symbols. Redundancy increases the likelihood of symbols being successfully decoded by a device receiving symbols from an AP, especially in regions with reduced SNR. The amount of redundancy needed to mitigate the reduced SNR generally depends on the delay channel spread (eg, for an outdoor communication channel), other signals interfering with the symbols, and/or other factors. do. In one embodiment, the HEW communication protocol defines a regular mode and a range extension mode. Normal mode is generally used with communication channels characterized by shorter channel delay spreads (eg, indoor communication channels) or generally higher SNR values, and the range extension mode is generally relatively in one embodiment. Used with communication channels characterized by longer channel delay spreads (eg, outdoor communication channels) or generally lower SNR values. In one embodiment, the regular coding technique is used in the regular mode, and the range extension coding technique is used in the range extension mode.

In one embodiment, the data unit transmitted by the AP is a preamble and a data part, the preamble being used, at least in part, to signal, to a receiving device, various parameters used for transmission of the data part. In various embodiments, the preamble of the data unit is used to signal to the receiving device at least the specific coding scheme being used for the data portion of the data unit. In some embodiments, the same preamble format is used in the regular mode as in the range extension mode. In one such embodiment, the preamble comprises an indication set to indicate whether a regular coding technique or a range extension coding technique is used for at least the data portion of the data unit. In some embodiments, the indicated regular coding scheme or range extension coding scheme is used for at least part of the preamble of the data unit in addition to the data part of the data unit. In one embodiment, the receiving device determines the particular coding scheme being used based on the indication in the preamble of the data unit, and then uses the particular coding scheme to convert the appropriate remaining portion of the data unit (e.g., the data portion, or part of the preamble and the data part).

In another embodiment, the preamble used in the range extension mode is formatted differently from the preamble used in the regular mode. For example, the preamble used in the range extension mode is formatted so that the receiving device can automatically (eg, before decoding) detect that the data unit corresponds to the range extension mode. In one embodiment, when the receiving device detects that the data unit corresponds to the range extension mode, the receiving device uses a range extension coding technique to use a data portion of the data unit, and, in at least some embodiments, at least a portion of the preamble. as well as decoding the data portion of the data unit. On the other hand, when the receiving device detects that the data unit does not correspond to the range extension mode, the receiving device assumes that the data unit corresponds to the normal mode in an embodiment. The receiving device then decodes at least the data portion of the data unit using a canonical coding technique in one embodiment.

Additionally in at least some embodiments, the preamble of the data unit in the regular mode and/or the range extension mode is specific to the data unit, such as the duration of the data unit, by a client station operating according to a legacy protocol other than the HEW communication protocol. information may be determined, and/or data units are formatted such that they do not conform to legacy protocols. Additionally, the preamble of the data unit is formatted such that it is possible for a client station operating according to the HEW protocol to determine whether the data unit conforms to the HEW communication protocol and whether the data unit is formatted according to the regular mode or the range extension mode in one embodiment. do. Similarly, in one embodiment, a client station configured to operate according to the HEW communication protocol also transmits data units as described above.

In at least some embodiments, data units formatted as described above have, for example, an AP configured to operate with client stations according to a plurality of different communication protocols and/or a plurality of client stations Having WLANs that operate according to different communication protocols is useful. Continuing with the example above, a communication device configured to operate according to both a HEW communication protocol (including a regular mode and a range extension mode) and a legacy communication protocol indicates that a given data unit conforms to the HEW communication protocol rather than the legacy communication protocol. It can be determined that it is formatted, and furthermore, it can be determined that the data unit is formatted according to the range extension mode rather than the regular mode. Similarly, a communication device configured to operate according to a legacy communication protocol other than the HEW communication protocol may determine that the data unit is not formatted according to the legacy communication protocol and/or may determine a duration of the data unit.

1 is a block diagram of an exemplary wireless local area network (WLAN) 10 in accordance with one embodiment. The AP 14 includes a host processor 15 coupled to a 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 , the transceiver 21 being coupled to a plurality of antennas 24 . Although three transceivers 21 and three antennas 24 are illustrated in FIG. 1 , the AP 14 may have other suitable numbers (eg, 1, 2, 4, 5, etc.) of transceivers in other embodiments. 21 and antennas 24 . In one embodiment, MAC processing unit 18 and PHY processing unit 20 operate according to a first communication protocol (eg, HEW communication protocol) comprising at least a first mode and a second mode of the first communication protocol. is configured to In some embodiments, the first mode is a range extension coding technique (eg, block encoding, bit-wise replication, or symbol replication), a signal modulation technique (eg, Corresponds to a range extension mode using phase shift keying or quadrature amplitude modulation, or both a range extension coding technique and a signal modulation technique. , to increase the range and/or reduce the signal-to-noise (SNR) ratio when successful decoding of PHY data units conforming to the range extension mode is performed, compared to a regular mode using a regular coding technique). In embodiments, the range extension mode reduces the data transmission rate to achieve successful decoding with increased range and/or reduced SNR ratio compared to the normal mode.In another embodiment, MAC processing unit 18 and PHY processing unit 20 is also configured to operate according to a second communication protocol (eg, IEEE 802.11ac standard) In another embodiment, MAC processing unit 18 and PHY processing unit 20 may additionally and operate according to the second communication protocol, the third communication protocol and/or the fourth communication protocol (eg, the IEEE 802.11a standard and/or the IEEE 802.11n standard).

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

The client station 25 - 1 includes a host processor 26 coupled to a 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 , which are coupled to a plurality of antennas 34 . Although three transceivers 30 and three antennas 34 are illustrated in FIG. 1 , the client station 25 - 1 may be configured in other suitable numbers (eg, 1, 2, 4, 5, etc.) in other embodiments. ) of transceivers 30 and antennas 34 .

According to an embodiment, the client station 25 - 4 is a legacy client station, ie the client station 25 - 4 is the data transmitted by the AP 14 or another client station 25 according to the first communication protocol. Receive the unit and make it completely undecodable. Similarly, according to an embodiment, the legacy client station 25 - 4 is not able to receive data units according to the first communication protocol. On the other hand, the legacy client station 25 - 4 makes it possible to receive, fully decode and transmit data units according to the second communication protocol, the third communication protocol and/or the fourth communication protocol.

In an 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 an embodiment, the client station 25-4 has a structure similar to that of the client station 25-1. In these embodiments, the client station 25 of the same or similar structure as the client station 25-1 has the same or a different number of transceivers and antennas. For example, the client station 25 - 2 has only two transceivers and two antennas (not shown) according to an embodiment.

In various embodiments, the PHY processing unit 20 of the AP 14 is configured to generate data units conforming to the first communication protocol and having the formats described herein. The transceiver(s) 21 is configured to transmit the generated data units via the antenna(s) 24 . Similarly, transceiver(s) 21 is configured to receive data units via antenna(s) 24 . The PHY processing unit 20 of the AP 14 processes received data units conforming to a first communication protocol and having the formats described hereinafter and determines that these data units conform to the first communication protocol, according to various embodiments. is configured to

In various embodiments, the PHY processing unit 29 of the client device 25 - 1 is configured to generate data units conforming to the first communication protocol and having the formats described herein. Transceiver(s) 30 is configured to transmit the generated data units via antenna(s) 34 . Similarly, transceiver(s) 30 is configured to receive data units via antenna(s) 34 . The PHY processing unit 29 of the client device 25-1 is configured to process received data units according to a first communication protocol and having the formats described hereinafter, according to various embodiments, and these data units are first configured to determine that it conforms to the communication protocol.

2A is a diagram of a prior art OFDM data unit 200 configured for an AP 14 to transmit to a legacy client station 25-4 via orthogonal frequency division multiplexing (OFDM) modulation, according to an embodiment. In an embodiment, the legacy client station 25 - 4 is also configured to transmit the data unit 200 to the AP 14 according to an embodiment. The data unit 200 conforms to the IEEE 802.11a standard and occupies a 20 megahertz (MHz) band. Data unit 200 is a legacy short training field (L-STF) 202, typically used for packet detection, initial synchronization, and automatic gain control, and the like, and generally used for channel estimation and fine synchronization. It contains a preamble with a legacy long training field (L-LTF) 204 . The data unit 200 is also a legacy signal field, used to convey certain physical layer (PHY) parameters of the data unit 200 , such as, for example, the coding rate and modulation type used to transmit the data unit. (L-SIG) 206 . The data unit 200 also includes a data portion 208 . 2B is a diagram of an exemplary data portion 208 (low density parity check unencoded), which contains a service field, a scrambled physical layer service data unit (PSDU), tail bits, and pad bits, as required. include Data unit 200 is designed for transmission over one space or space-time stream in a single input single output (SISO) channel configuration.

3 is a diagram of a prior art OFDM data unit 300 in which an AP 14 is configured to transmit to a legacy client station 25-4 via orthogonal frequency domain multiplexing (OFDM) modulation, according to an embodiment. In an embodiment, the legacy client station 25 - 4 is also configured to transmit the data unit 300 to the AP 14 according to an embodiment. The data unit 300 conforms to the IEEE 802.11n standard, occupies the 20 MHz band, and in mixed mode situations, ie, when the WLAN contains one or more client stations that conform to the IEEE 802.11a standard but not the IEEE 802.11n standard. It is designed for Data unit 300 includes L-STF 302 , L-LTF 304 , L-SIG 306 , High Throughput Signal Field (HT-SIG) 308 , High Throughput Short Training Field (HT-STF) 310, and a preamble with M data high throughput long training fields (HT-LTFs) 312, where M is typically a data unit 300 in a multiple input multiple output (MIMO) channel configuration. ) is an integer determined by the number of spatial streams used to transmit. In particular, according to the IEEE 802.11n standard, a data unit 300 comprises two HT-LTFs 312 if the data unit 300 is transmitted using two spatial streams, and four HT-LTFs ( 312 is a data unit 300 that is transmitted using 3 or 4 spatial streams. An indication of the specific number of spatial streams to be used is included in the HT-SIG field 308 . The data unit 300 also includes a data portion 314 .

4 is a diagram of a prior art OFDM data unit 400 in which an AP 14 is configured to transmit to a legacy client station 25-4 via orthogonal frequency domain multiplexing (OFDM) modulation, in accordance with an embodiment. In an embodiment, the legacy client station 25 - 4 is also configured to transmit the data unit 400 to the AP 14 . The data unit 400 complies with the IEEE 802.11n standard, occupies the 20 MHz band, and in “Greenfield” situations, i.e. the WLAN does not contain any client stations conforming to the IEEE 802.11a standard, It is designed for when it contains only client stations conforming to the n standard. The data unit 400 includes a high throughput greenfield short training field (HT-GF-STF) 402 , a first high throughput long training field (HT-LTF1) 404 , an HT-SIG 406 , and M contains the preamble with data HT-LTFs 408 , where M is generally an integer corresponding to the number of spatial streams used to transmit the data unit 400 in a multiple input multiple output (MIMO) channel configuration. The data unit 400 also includes a data portion 410 .

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

6A is a set of diagrams illustrating modulation of the L-SIG, HT-SIG1, and HT-SIG2 fields of the data unit 300 of FIG. 3 as defined by the IEEE 802.11n standard. The L-SIG field is modulated according to binary phase shift keying (BPSK), whereas the HT-SIG1 and HT-SIG2 fields are modulated according to BPSK, but not on the quadrature axis (Q-BPSK). In other words, the modulation of the HT-SIG1 and HT-SIG2 fields is rotated by 90 degrees compared to the modulation of the L-SIG field.

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

7A is a diagram of an OFDM data unit 700 that the AP 14 is configured to transmit to a client station 25-1 via orthogonal frequency domain multiplexing (OFDM) modulation, according to one embodiment. In an 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. Data units conforming to a first communication protocol similar to data unit 700 occupy other suitable bandwidths, such as, for example, 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz, or in other embodiments, other suitable bandwidths. Data unit 700 may be used in “mixed mode” situations, i.e., a client station in which WLAN 10 conforms to a legacy communication protocol but not a first communication protocol (eg, legacy client station 25-4). It is suitable when including Data unit 700, in some embodiments, is also used in other situations.

Data unit 700 includes L-STF 702 , L-LTF 704 , L-SIG 706 , a first HEW signal field (HEW-SIGA1) 708-1 and a second HEW signal field (HEW). Two first HEW signal fields (HEW-SIGAs) 708, including -SIGA2) 708-2, a HEW short training field (HEW-STF) 710, M HEW long training fields ( HEW-LTFs) 712 (where M is an integer), and a preamble 701 having a third HEW signal field (HEW-SIGB) 714 . L-STF 702 , L-LTF 704 , L-SIG 706 , HEW-SIGAs 708 , HEW-STF 710 , M HEW-LTFs 712 , and HEW- SIGB 714 includes an integer number of one or more OFDM symbols. For example, in one embodiment, HEW-SIGAs 708 include two OFDM symbols, where HEW-SIGA1 708-1 field includes a first OFDM symbol and HEW-SIGA2 includes a second OFDM symbol. Includes OFDM symbols. In another embodiment, for example, the preamble 701 includes a third HEW signal field (HEW-SIGA3, not shown) and the HEW-SIGAs 708 include three OFDM symbols, HEW-SIGA1 ( 708-1) field includes a first OFDM symbol, HEW-SIGA2 includes a second OFDM symbol, and HEW-SIGA3 includes a third OFDM symbol. In at least some examples, the HEW-SIGAs 708 are collectively referred to as a single HEW signal field (HEW-SIGA) 708 . In some embodiments, data unit 700 also includes a data portion 716 . In other embodiments, data unit 700 omits data portion 716 .

In the embodiment of FIG. 7A , data portion 700 includes one of each of L-STF 702 , L-LTF 704 , L-SIG 706 , and HEW-SIGA1s 708 . 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 , HEW-SIGA1s ( 708) is repeated over a corresponding number of 20 MHz sub-bands of the total bandwidth of the data unit, in one embodiment. For example, in an embodiment, an OFDM data unit occupies 80 MHz bandwidth, thus, in the embodiment L-STF 702 , L-STF 704 , L-SIG 706 , HEW-SIGA1s 708 ), including 4 of each. In some embodiments, the modulation of different 20 MHz sub-bandwidth signals is rotated by different angles. For example, in one embodiment, the first subband is rotated 0-degrees, the second subband is rotated 90-degrees, the third sub-band is rotated 180-degrees, and the fourth sub-band is 270 degrees rotated. - is also rotated. In other embodiments, different suitable rotations are used. Different phases of the 20 MHz sub-band signals result in a reduced peak to average power ratio (PAPR) of OFDM symbols in data unit 700 , in at least some embodiments. In an embodiment, if the data unit conforming to the first communication protocol is an OFDM data unit occupying an accumulated bandwidth such as 20 MHz, 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz, HEW-STF, HEW-LTFs, HEW-SIGB and HEW data The portion occupies the corresponding total bandwidth of the data unit.

7B is a diagram of diagrams illustrating modulation of L-SIG 706 , HEW-SIGA1 708 - 1 , and HEW-SIGA2 708 - 2 of data unit 700 of FIG. 7A , according to one embodiment. is a set 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 of the corresponding fields as depicted in FIG. 6B. It has the same modulation as the modulation. Accordingly, the HEW-SIGA1 field is modulated in the same way as the L-SIG field. On the other hand, the HEW-SIGA2 field is rotated by 90 degrees compared to the modulation of the L-SIG field. In some embodiments having a third HEW-SIGA3 field, the HEW-SIGA2 field is modulated identically to the L-Sig field and the HEW-SIGA1 field, whereas the HEW-SIGA3 field is an L-Sig field, a HEW-SIGA1 field, and rotated by 90 degrees compared to the modulation of the HEW-SIGA2 field.

In an embodiment, modulations of the L-SIG 706, HEW-SIGA1 708-1, and HEW-SIGA2 708-2 fields of the data unit 700 are performed in a data unit conforming to the IEEE 802.11ac standard (eg , corresponding to modulations of corresponding fields in data unit 500 of FIG. 5 , legacy client stations configured to operate in accordance with the IEEE 802.11a standard and/or the IEEE 802.11n standard may, in at least some circumstances, It will be assumed that 700 conforms to the IEEE-802.11ac standard and will process the data unit 700 accordingly. For example, a client station conforming to the IEEE 802.11a standard may have a legacy IEEE It will be aware of the 802.11a standard and set the duration (or data unit duration) of the data unit according to the duration indicated in the L-SIG 706. For example, according to one embodiment, the legacy client station 25 -4) will yield the duration for the data unit based on the rate and length (eg, number of bytes) indicated in the L-SIG field 706. In an embodiment, the L-SIG field ( The rate and length at 706 are determined by a client station configured to operate in accordance with the legacy communication protocol to determine, based on the rate and length, a packet duration T corresponding to, or at least approximating, the actual duration of the data unit 700 . For example, in one embodiment, the rate is set to indicate the lowest rate defined by the IEEE 802.11a standard (ie, 6 Mbps), and the length is the packet duration calculated using the lowest rate. This at least is set to a value calculated to approximate the actual duration of the data unit 700 .

In one embodiment, the legacy client station conforming to the IEEE-802.11a standard, when receiving the data unit 700 , using, for example, the rate field and the length field of the L-SIG field 706 , It will compute the packet duration for the data unit 700 and, in one embodiment, wait until the end of the computed packet duration before performing clear channel assessment (CCA). Thus, in this embodiment, the communication medium is protected against evaluation by the legacy client station for at least the duration of the data unit 700 . In an embodiment, the legacy client station will continue to decode data unit 700 , but will fail error checking (eg, frame check sequence (FCS)) at the end of data unit 700 .

Similarly, a legacy client station configured to operate in accordance with the IEEE 802.11n standard, in one embodiment, when receiving the data unit 700 , is at the rate and length indicated in the L-SIG 706 of the data unit 700 . based on the packet duration T of the data unit 700 will be calculated. The legacy client station will detect modulation of the first HEW signal field (HEW-SIGA1) 708-1 (BPSK) and assume that the data unit 700 is a legacy data unit conforming to the IEEE-802.11a standard. In an embodiment, the legacy client station will continue to decode the data unit 700 , but will fail error checking (eg, using a frame check sequence (FCS)) at the end of the data unit. In any event, in accordance with the IEEE 802.11n standard, the legacy client station will, in one embodiment, wait until the end of the calculated packet duration (T) before performing a clear channel assessment (CCA). Accordingly, the communication medium will, in an embodiment, be protected from access by legacy client stations for the duration of the data unit 700 .

A legacy client station configured to operate in accordance with the IEEE 802.11ac standard other than the first communication protocol, when receiving the data unit 700 , in an embodiment, may, when receiving the data unit 700 at the rate indicated in the L-SIG 706 of the data unit 700 and We will calculate the packet duration T of the data unit 700 based on the length. However, the legacy client station, in an embodiment, will not be able to detect, based on the modulation of the data unit 700 , that the data unit 700 does not comply with the IEEE 802.11ac standard. In some embodiments, one or more HEW signal fields (eg, HEW-SIGA1 and/or HEW-SIGA2) of data unit 700 intentionally contain an error when the legacy client station decodes data unit 700 . It is formatted to cause detection and thus to stop (or “drop”) decoding the data unit 700 . For example, the HEW-SIGA 708 of the data unit 700 is, in one embodiment, formatted intentionally to cause an error when the SIGA field is decoded by a legacy device according to the IEEE 802.11ac standard. In addition, according to the IEEE 802.11ac standard, when an error is detected when decoding the VHT-SIGA field, the client station, in an embodiment, will drop the data unit 700 and before performing a clear channel assessment (CCA). , eg, will wait until the end of the calculated packet duration T, calculated based on the rate and length indicated in the L-SIG 706 of the data unit 700 . Accordingly, the communication medium will, in one embodiment, be protected from access by legacy client stations for the duration of the data unit 700 .

8 is a block diagram of an OFDM symbol 800 according to an embodiment. The data unit 700 of FIG. 7 includes OFDM symbols such as OFDM symbols 800 in one embodiment. The 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 repeating the end portion of the OFDM symbol. In one embodiment, the guard interval portion 802 is inter-symbol due to multi-path propagation in a communication channel via any OFDM symbol 800 transmitted from a transmitting device (eg, AP 14) to a receiving device. It is used to minimize or eliminate interference and to ensure orthogonality of OFDM tones at the receiving device (eg, client station 25-1). In one embodiment, the length of the guard interval portion 802 is selected based on an expected worst case channel delay spread in a communication channel between the transmitting device and the receiving device. For example, in one embodiment a longer guard interval is typically characterized by longer channel delay spreads as compared to a shorter guard interval selected for indoor communication channels that are typically characterized by shorter channel delay spreads. It is selected for outdoor communication. In one embodiment, the length of the guard spacing portion 802, along with which information portion 804 was generated, is the tone spacing (eg, the spacing between sub-carrier frequencies of the entire bandwidth of the data unit). ) is selected based on For example, a longer guard interval is selected for a narrower tone spacing (eg, 256 tones) compared to a shorter guard interval for a wider tone spacing (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 being used. . In one embodiment, the short guard interval or normal guard interval is used for indoor communication channels, communication channels with relatively short channel delay spreads, or communication channels with suitably high SNR ratios, and the long guard interval is for outdoor communication channels, communication channels with relatively long delay spreads, or communication channels that do not have suitably high SNR ratios. In one embodiment, the normal guard interval or short guard interval is used for some or all OFDM symbols of a HEW data unit (eg, HEW data unit 700 ) when the HEW data unit is transmitted in regular mode, and the long guard The interval is used for at least some OFDM symbols of the HEW data unit when the HEW data unit is transmitted in the range extension mode.

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. 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 tone interval over which the information portion 804 is generated. For example, the information portion 804 has a first length of 3.2 μs for a regular mode using a first tone interval of 64 tones and a second length of 6.4 μs for a second tone interval of 128 tones; The two tone spacing and the second length are both increased by an integer multiple of two 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 is a portion of the received time-domain signal). accommodates two copies). In other embodiments, SGI, NGI, LGI, and/or other suitable lengths for 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 of 75% or less of the length of the NGI, and the NGI has a length of 75% or less of the length of the LGI. In other embodiments, the SGI has a length of 50% or less of the length of the NGI, and the NGI has a length of 50% or less of the length of the LGI.

In other embodiments, OFDM modulation with reduced tone spacing is used in range extension mode using the same tone plan (e.g., which OFDM tones are designated for data tones, pilot tones, and/or guard tones) a predetermined sequence of indices indicating whether For example, the normal mode for a 20 MHz bandwidth OFDM data unit uses a 64-point Discrete Fourier Transform (DFT) that results in 64 OFDM tones (eg, indices -32 to +31), whereas the range extension The mode uses a 128-point DFT for a 20 MHz OFDM data unit that results in 128 OFDM tones (eg, indices -64 to +63) in the same bandwidth. In this case, the tone spacing in the range extension mode OFDM symbols is reduced by a factor of 2 compared to the regular mode OFDM symbols while using the same tone plan (1/2). As another example, the regular mode for a 20 MHz bandwidth OFDM data unit uses a 64-point Discrete Fourier Transform (DFT) resulting in 64 OFDM tones, while the range extension mode results in 256 OFDM tones in the same bandwidth 20 MHz OFDM A 256-point DFT is used for the data unit. In this case, the tone spacing in the range extension mode OFDM symbols is reduced by a factor of 4 compared to the regular mode OFDM symbols (1/4). In such embodiments, a long GI duration of, for example, 1.6 μs is used. However, in one embodiment the duration of the information portion of the range extension mode OFDM symbol is increased (eg, from 3.2 μs to 6.4 μs), and the percentage of total OFDM symbols duration to GI portion duration remains the same. do. Thus, in this case, an efficiency loss is avoided due to a longer GI symbol in at least some embodiments. In various embodiments, the term “long guard interval” as used herein encompasses an increased duration of the guard interval as well as a reduced OFDM tone interval that effectively increases the duration of the guard interval.

9A is a diagram illustrating an example data unit 900 in which a regular mode or a range extension mode is used for a preamble of a data unit according to an embodiment. Data unit 900 is generally identical to data unit 700 of FIG. 7A and includes the same-numbered elements as 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 an embodiment, the CI indication 902 is set to indicate one of (i) a regular mode with a regular coding scheme or (ii) a range extension mode with a range extension coding scheme. Indication 902 includes one bit, a first value of that bit indicates a normal mode and a second value of that bit indicates a range extension mode In some embodiments, the CI indication is a modulation and coding scheme ( MCS: modulation and coding scheme) indicator In one embodiment, for example, the regular mode corresponds to MCS values (e.g. conforming to IEEE 802.11ac protocol) determined to be valid by the legacy receiver device. In other embodiments, the CI indication 902 ) has a plurality of bits representing a plurality of regular mode MCS values and a plurality of range extension mode MCS values, As illustrated in Fig. 9a , the regular coding scheme is used for all OFDM symbols of the preamble of the data unit 700 , either range extension coding or canonical coding scheme, indicated by CI indication 902 , is used for OFDM symbols of data portion 716 in the illustrated embodiment.

In one embodiment, for example, if a range extension coding scheme is used for OFDM symbols of data portion 716 , the range and/or SNR in successful decoding of PHY data units may be compared to normal data units in overall Improved (ie, successful decoding at longer range and/or lower SNR). In some embodiments, improved range and/or SNR performance is not necessarily achieved for decoding of the preamble 701 generated using a canonical coding technique. In such embodiments, the transmission of at least the portion of the preamble 701 with a predetermined transmit power to increase the decoding range of the portion of the preamble 701 is compared to the transmit power used for the transmission of the data portion 716 . is boosted. In some embodiments, the portion of the preamble 701 transmitted with transmit power boost includes legacy fields, such as L-STF 702 , L-LTF 704 , and L-SIG 708 , and/or ratio -Contains legacy fields such as HEW-STF and HEW-LTF. In various embodiments, the transmit power boost is 3 dB, 6 dB, or other suitable values. In some embodiments, the transmit power boost is determined such that the “boosted” preamble 701 is decodable with similar performance compared to the “unboosted” data portion 716 at the same location with similar performance. do. In some embodiments, used in combination with a transmit power boost of L-STF 702 , L-LTF 704 , and/or L-SIG 706 . In other embodiments, an increased length of L-STF 702 , L-LTF 704 , and/or L-SIG 706 is used instead of transmit power boost.

9B is a diagram illustrating an example data unit 950 in which a range extension coding scheme is used for a preamble portion of a data unit according to an embodiment. The data unit 950 is a preamble 751 in which the data unit 950 is applied to the OFDM symbols of the data portion 716 as well as the OFDM symbols of the portion of the preamble 751 , the coding scheme indicated by the CI indication 902 . ) is generally the same as data unit 900 of FIG. 9A , except that it includes Specifically, in the illustrated embodiment, a canonical coding technique is used for the first part 751-1 of the preamble 701, and one of the range extension coding technique or the canonical coding technique, indicated by the CI indication 902, is It is used for OFDM symbols of the second part 751-2 of the preamble 751 in addition to the OFDM symbols of the part 716 . Accordingly, the coding scheme indicated by the CI indication 902 is applied, skipping the OFDM symbol corresponding to the HEW-STF 710 and starting with the OFDM symbol corresponding to the HEW-LTF 712-1 in the illustrated embodiment. . In at least some embodiments skipping the HEW-STF 710 uses a coding scheme indicated by the CI indication 902 prior to decoding the CI indication 902 and receiving such OFDM symbols for OFDM symbols. Allow the device receiving the data unit 950 sufficient time to properly set up the receiver to begin decoding.

10A is a diagram illustrating an example data unit 1000 in which OFDM tone spacing adjustment is used in combination with bit and/or symbol repetition for a range extension coding scheme, according to one embodiment. Data unit 1000 indicates that, within data unit 1000, OFDM symbols of data portion 716 are regular mode OFDM symbols of data unit 1000 when CI indication 902 indicates that a range extension coding scheme is being used. It is generally identical to data unit 900 of FIG. 7A except that it is generated using OFDM modulation with a reduced tone spacing compared to the tone spacing used for .

10B is a diagram illustrating an example data unit 1050 in which OFDM tone spacing adjustment is used in combination with bit and/or symbol repetition for a range extension coding scheme, according to another embodiment. Data unit 1050 includes, within data unit 1050, OFDM symbols in data portion 716 and OFDM in second portion 751-2 when CI indication 902 indicates that a range extension coding scheme is being used. Generally identical to data unit 950 of FIG. 9B , except that the symbols are generated using OFDM modulation with a reduced tone spacing compared to the tone spacing used for the normal mode OFDM symbols of data unit 1050 . Do. In the embodiment shown in Fig. 10a, the total bandwidth of 20 MHz is the normal tone spacing and guard interval in the first portion 751-1 over the entire bandwidth and the tone spacing reduced by two; A long guard interval, and an FFT of size 64 repeated twice is used. In some embodiments, a 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 used for one or more of reduced tone spacing, increased guard spacing, increased symbol duration, or increased repetition across the entire bandwidth. .

In some embodiments, a different preamble format is used for range extension mode data units compared to the preamble used for regular mode data units. In such embodiments, the device receiving the data unit may automatically detect whether the data unit is a regular mode data unit or a range extension mode data unit based on the format of the preamble of the data unit. 11A is a diagram illustrating a normal mode data unit 1100 according to one embodiment. The regular mode data unit 1100 includes a regular mode preamble 1101 . The regular mode preamble 1101 is generally 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 including a first HEW-SIGA1 field 1108 - 1 and a second first HEW-SIGA2 field 1108 - 1 . In one embodiment, the HEW-SIGA field 1108 of the preamble 1101 (eg, HEW-SIGA1 1108-1 or HEW-SIGA2 1108-2) includes the CI indication 1102 . In one embodiment, the CI indication 1102 is set to indicate whether a range extension coding scheme or a canonical coding scheme is used for the OFDM symbols of the data portion 716 of the data unit 1100 . In one embodiment, the CI indication 1102 includes one bit, wherein a first value of the bit indicates a regular coding scheme and a second value of that bit indicates a range extension coding scheme. As described in more detail below, in one embodiment, the device receiving the data unit 1100 determines, based on the format of the preamble 1101, that the preamble 1101 is a regular mode preamble and not an extended mode preamble. can detect Upon detecting that the preamble 1101 is a regular mode preamble in an embodiment, based on the CI indication 1102 the receiving device determines whether a range extension coding scheme or a regular coding scheme is used for OFDM symbols of the data portion 716 and It determines whether or not to decode the data portion 716 accordingly. In some embodiments, OFDM symbols (eg, HEW-LTFs and HEW-SIGB) and data portion of the portion of the preamble 1101 when the CI indication 1102 indicates that a range extension coding scheme is being used The OFDM symbols of 716 are generated using OFDM modulation with a smaller tone spacing compared to the tone spacing used for the regular mode OFDM symbols of data unit 1050 .

11B is a diagram illustrating a range extension mode data unit 1150 according to an embodiment. The range extension mode data unit 1150 includes a range extension mode preamble 1151 . Data unit 1150 is generally similar to data unit 1100 of FIG. 11A , except that preamble 1151 of data unit 1150 is formatted differently than preamble 1101 of 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 a range extension mode preamble instead of a regular mode preamble. In one embodiment, the range extension mode preamble 1151 includes L-STF 702 , L-LTF 704 , and L-SIG 706 , and one or more first HEW signal fields (HEW-SIGAs). (1152). In one embodiment, the preamble 1150 further includes one or more second L-SIG(s) 1154 following the L-Sig field 706 . In some embodiments the second L-SIG(s) 1154 is followed by a second L-LTF field (L-LTF2) 1156 . In other embodiments, the preamble 1151 omits the L-SIG(s) 1154 and/or the L-LTF2 1156 . In some embodiments, the preamble 1151 also includes a HEW-STF 1158 , one or more HEW-LTF fields 1160 , and a second HEW signal field (HEW-SIGB) 1162 . In other embodiments, the preamble 1151 omits the HEW-STF 1158 , HEW-LTF(s) 1160 and/or HEW-SIGB 1162 . In one embodiment, data unit 1150 also includes data portion 716 (not shown in FIG. 11B ). In some embodiments, HEW signal fields (HEW-SIGAs) 1152 are modulated using the same range extension coding technique as data field 716 .

In one embodiment, one or more symbols of the HEW-SIGAs 1152 may be QBPSK instead of BPSK, for example, to allow automatic detection between regular mode and range extension mode by a receiving device operating in accordance with the HEW communication protocol. is modulated using In one embodiment, for example, when the regular mode preamble includes two BPSK symbols and one Q-BPSK symbol after the L-SIG 706 field, the range extension mode preamble includes three BPSK symbols and L One Q-BPSK symbol is included after the -SIG 706 field. In one embodiment, for example, we have 48 data tones in each 64-FFT (20MHz) when using 4x bit-wise repetition of MCS0. In some embodiments, for example, in case of auto-sensing distinction between range extension mode and regular mode, some bits, such as bits used to indicate signal bandwidth, MCS value or other suitable bits, are HEW- omitted from SIGAs 1152 .

In an embodiment in which the preamble 1151 includes one or more second L-SIG(s) 1154 , the content of each L-SIG(s) 1154 is the L-SIG ( 706). In one embodiment, the receiving device receiving the data unit 1150 determines that the preamble 1151 corresponds to a range extension mode preamble by detecting repetition(s) of the L-Sig fields 706 and 1154 . Moreover, in one embodiment, the rate subfield and length subfield of the L-SIG 706 , and thus the rate subfield(s) and length of the second L-SIG(s) 1154 , 1154 . The subfield(s) are set to fixed (eg, predetermined) values. In this case, upon detecting the repetition(s) of the L-Sig fields 706, 1154 in one embodiment, the receiving device fixes the fixed in the repetition L-Sig fields as additional training information to improve the channel estimation. use values. However, in some embodiments, at least the length subfield of L-SIG 706 , and thus at least the length fields of second L-SIG(s) 1154 are not set to a fixed value. For example, instead, in one embodiment, the length field is set to a value determined based on the actual length of data unit 1150 . In one such embodiment, the receiving device first decodes the L-SIG 706 , and then uses the value of the length subfield in the L-SIG 706 to repeat the L-Sig fields 706 , 1154 . detect(s) In another embodiment, the receiving device first senses the repetition(s) of the L-Sig fields 706, 1154 and then the sensed multiple to improve the decoding reliability of the L-Sig fields 706, 1154. Combine the L-Sig fields 706, 1154 and/or use redundancy information in multiple L-Sig fields 706, 1154 to improve channel estimation.

In one embodiment where the preamble 1151 includes the L-LTF2 1156 , the OFDM symbol(s) of the L-LTF2 1156 are generated using a range extension coding technique. In another embodiment, where the preamble 1151 includes the L-LTF2 11156, the OFDM symbol(s) of the L-LTF2 1156 are generated using a canonical coding technique. For example, in one embodiment if the double guard interval (DGI) used for the L-LTF 704 is long enough for the communication channel through which the data unit 1150 travels from the transmitting device to the receiving device, The OFDM symbols of the L-LTF2 1156 are then generated using a regular coding technique, or, alternatively, the preamble 1151 omits the L-LTF2 1156 .

In other embodiments, the preamble 1151 omits the second L-SIG(s) 1154 but includes the L-LTF2 1156 . In this embodiment, the receiving device detects that the preamble 1151 is a range extension mode preamble by detecting the presence of the L-LTF2 1156 . 12A-12B are diagrams illustrating two possible formats of LTFs suitable for use as L-LTF2 1156 in accordance with two example embodiments. Turning first to FIG. 12A , in a first exemplary embodiment, L-LTF2 1200 is configured in the same manner as L-LTF 704 , ie, a legacy communication protocol (eg, IEEE 802.11a/n/ac standard). ) are formatted as defined by Specifically, in the illustrated embodiment, L-LTF2 1200 includes a double guard interval (DGI) 1202 , followed by two repetitions of a long training sequence 1204 , 1206 . Turning now to FIG. 12B , in another example embodiment, L-LTF2 1208 is formatted differently than L-LTF 704 . Specifically, in the illustrated embodiment, L-LTF2 1208 includes a first normal guard interval 1210 , a first repetition of a long training sequence 1212 , a second normal guard interval 1214 , and a long training sequence 1216 . ) and the second iteration of

Turning back to FIG. 11B , in one embodiment, the HEW-SIGA(s) 1152 are generated using a range extension coding technique. In one embodiment, the number of HEW-SIGAs 1152 is equal to the number of HEW-SIGA(s) 1108 in the regular mode preamble 1101 . Similarly, in one embodiment, the content of the HEW-SIGAs 1152 is the same as the content of the HEW-SIGA(s) 1108 of the regular mode preamble 1101 . In other embodiments, the number and/or content of HEW-SIGAs 1152 is different from the number and/or content of HEW-SIGA(s) 1108 of the regular mode preamble 1101 . In one embodiment, the device receiving the data unit 1150 writes the HEW-SIGA(s) 1152 using a range extension coding technique based on detecting that the preamble 1151 corresponds to a range extension mode preamble. Decode and interpret HEW-SIGA(s) 1152 defined appropriately for range extension mode.

In an embodiment in which the preamble 1151 omits the L-SIG(s) 1154 and/or the L-LTF2 1156, the receiving device automatically - By detecting whether the HEW-SIGA field in the preamble is generated using a range extension coding technique or a regular coding technique based on auto-correlation, the preamble is a range extension mode preamble (1151) or a normal mode preamble (1101) ) to determine whether or not 13A-13B are diagrams of HEW-SIGA 1108 of regular mode preamble 1101 and HEW-SIGA 1152 of range extension mode preamble 1151 , respectively, according to an embodiment. In the illustrated embodiment, the HEW-SIGA 1108 of the regular 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 range extension mode preamble 1151 includes the first LGI 1310, the first HEW-SIGA field 1312, the second LGI 1314, and the second HEW-SIGA field ( 1312). In one embodiment, the receiving device performs the first auto-correlation of the HEW-SIGA field using a normal guard interval structure, such as the structure illustrated in FIG. 13A, and a long guard interval structure, such as the structure illustrated in FIG. 13B. to perform a second auto-correlation, and compare the auto-correlation results. In one embodiment, if the auto-correlation of the HEW-SIGA field using the long guard interval produces a larger result compared to the result of the auto-correlation of the HEW-SIGA field using the normal guard interval, then the receiving device It is determined that the preamble corresponds to the range extension mode preamble 1151 . In one embodiment, if the auto-correlation of the HEW-SIGA field using the normal guard interval produces a larger result compared to the result of the auto-correlation of the HEW-SIGA field with the long guard interval, then the receiving device It is determined that the preamble corresponds to the regular mode preamble 1101 .

Referring again to FIG. 11B , in one embodiment, the preamble 1151 is formatted such that the legacy client station may determine the duration of the data unit 1150 and/or the data unit does not conform to the legacy communication protocol. Additionally, in one embodiment, the preamble 1151 is formatted such that a client station operating according to the HEW protocol can determine that the data unit is compliant with the HEW communication protocol. For example, at least two OFDM symbols immediately following L-SIG 706 of preamble 1151 , such as L-SIG(s) 1154 and/or L-LTF2 1156 and/or HEW- The SIGA(s) 1152 is modulated using BPSK modulation. In this case, in one embodiment the legacy client station will treat the data unit 1150 as a legacy data unit, determine the duration of the data unit based on the L-SIG 706, and transfer the determined duration to the medium. will refrain from accessing it. Moreover, in one embodiment one or more other OFDM symbols of the preamble 1151 , such as one or more HEW-SIG(s) 1152 are modulated using Q-BPSK modulation, and a client station operating according to a HEW communication protocol. to detect if the data unit 1150 complies with the HEW communication protocol.

In some embodiments, the HEW communication protocol allows for beamforming and/or multi user MIMO (MU-MIMO) transmission in a range extension mode. In other embodiments, the HEW communication protocol allows only single stream and/or only single user transmission in range extension mode. With continued reference to FIG. 11B , in one embodiment where the preamble 1151 includes HEW-STF 1158 and HEW-LTF(s) 1160 , AP 14 begins with HEW-STF 1158 . Apply beamforming and/or multi-user transmission. In other words, the fields of the preamble 1151 preceding the HEW-STF 1158 in one embodiment are omni-directional and are intended to be received by all intended recipients of the data unit 1150 in multi-user mode, Whereas the HEW-STF field 1158 following the HEW-STF field 1158, as well as the preamble fields and the data portion following the preamble 1151 are beam-shaped and/or other intents of the data unit 1150 different parts intended to be received by the intended recipients. In one embodiment, the HEW-SIGB field 1162 contains user-specific information for intended recipients of the data unit 1150 in MU-MIMO mode. The HEW-SIGB field 1162 is generated using a regular coding technique or a range extension coding technique according to an embodiment. Similarly, the HEW-STF 1158 is generated using a regular coding technique or a range extension coding technique according to an embodiment. In one embodiment, the training sequence used on HEW-STF 1158 is a sequence defined in a legacy communication protocol, such as the IEEE 802.11ac protocol.

On the other hand, in one embodiment where the preamble 1151 omits the HEW-STF 1158 and HEW-LTF(s) 1160 , beamforming and MUMIMO are not allowed in the extended guard interval mode. In this embodiment, only single user single stream transmission is allowed in extended guard interval mode. In one embodiment, the receiving device obtains a single stream channel estimate based on the L-LTF field 704 , and based on the obtained channel estimate based on the L-LTF field 704 , the data in the data unit 1150 is demodulate the part

In some embodiments, the receiver device uses the HEW-STF field 1158 to resume an automatic gain control (AGC) process for receiving the data portion 716 . HEW-STF has a duration equal to VHT-STF (ie, 4 microseconds) in one embodiment. In other embodiments, the HEW-STF has a longer duration than the VHT-STF. In one embodiment, HEW-STF has the same time-domain periodicity as VHT-STF, using the same tone spacing as IEEE 802.11ac in the frequency domain and there is one non-zero tone for every 4 tones. In other embodiments with 1/N tone spacing, HEW-STF has one non-zero tone 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.), HEW-STF uses the same wide bandwidth VHT-STF as in IEEE 802.11ac ( That is, overlapping of 20 MHz VHT-STF for the total bandwidth of 40 MHz, 80 MHz, 160 MHz, etc.).

14A is a diagram illustrating a range extension mode data unit 1400 according to an embodiment. The data unit 1400 includes a range extension mode preamble 1401 . The range extension mode preamble 1401 is shown except that the L-SIG 706 and the second L-SIG 1154 of the preamble 1151 are combined into a single L-Sig field 1406 in the preamble 1401. It is generally similar to the range extension mode preamble 1151 of 11b. 14B is a diagram illustrating the L-Sig field 1406 according to one embodiment. In the embodiment of FIG. 14B , the L-Sig field 1406 is a double guard interval 1410 , a first L-Sig field 1412 containing the contents of the L-Sig field 706 of the preamble 1151 , and and a second L-Sig field 1414 including contents of the second L-SIG2 field 1154 of the preamble 1151 . In various embodiments, the L-Sig field 1406 includes a length subfield set to a fixed value or set to a variable value as discussed above with respect to the L-Sig fields 706 and 1154 of FIG. 11B . include In various embodiments, redundant (repeated) bits in L-Sig field 1406 are used for improved channel estimation as discussed above with respect to L-Sig fields 706 and 1154 in FIG. 11B . do.

In one embodiment, the legacy client station receiving the data unit 1400 assumes that the L-Sig field 1406 contains a normal guard interval. As illustrated in FIG. 14C , the FFT window for the L-SIG information bits assumed in the legacy client station in this embodiment is shifted compared to the actual L-Sig field 1412 . In one embodiment, to ensure that constellation points within the FFT window correspond to BPSK modulation as expected by the legacy client station, thus allowing the legacy client station to properly decode the L-Sig field 1412 For this purpose, the modulation of the L-Sig field 1412 is phase-shifted with respect to the regular BPSK modulation. For example, in a 20MHz OFDM symbol, if the normal guard interval is 0.8 μs and the double guard interval is 1.6 μs, then the modulation of OFDM tone k in the L-Sig field 1412 is the original L- Transitions for the corresponding OFDM tone k of the SIG:

방정식 1

Equation 1

Thus, in one embodiment, the L-Sig field 1412 is modulated using inverse Q-BPSK instead of regular BPSK. Thus, in one embodiment, for example, bits of value 1 are modulated on -j, bits of value 0 are modulated on j, {j, -j} modulation instead of regular {1, -1} BPSK modulation is concluded with In one embodiment, because of the inverse Q-BPSK modulation of the L-Sig field 1412, the legacy client station in one embodiment is able to properly decode the L-Sig field 1412 and Based on the duration of the data unit 1400 can be determined. On the other hand, in one embodiment, the client station operating according to the HEW protocol detects the repetition of the L-Sig field 1412 or inverse Q-BPSK modulation of the L-Sig field in the FFT window of the legacy client station by detecting the preamble ( 1401) may be auto-detected as the range extension mode preamble. Alternatively, in other embodiments, the client station operating in accordance with the HEW protocol uses other sensing methods discussed above, such as based on the modulation or format of the HEW-SIGA field(s) 1152 , the preamble ( 1401) is the range extension mode preamble.

Referring to FIGS. 11A-11B and 14A , in some embodiments, the long guard interval is a regular mode preamble (eg, preamble 1101 ) and a range extension mode preamble (eg, preamble 1151 or preamble 1401 ). ))) for both original OFDM symbols.For example, with reference to Figures 11a-11b, in one embodiment L-STF field 702, L-LTF field 704 and L-Sig field 706, 1154, and HEW-SIGA field 1152 are generated using a long guard interval, respectively. Similarly, with reference to Figure 14A, in one embodiment, L-STF field 702, L-LTF Field 704 and L-Sig field 1406, and HEW-SIGA(s) 1152 are each generated using a long guard interval In one embodiment, based on modulation of HEW-SIGA field 1152 (eg, Q-BPSK) or based on an indication included in the HEW-SIGA field 1152, the receiving device determines whether the preamble corresponds to the regular mode preamble or the range extension mode preamble in various embodiments Moreover, similar to the preamble 1151 of FIG. 11B , the preamble 1401 of FIG. 14A includes or omits the second L-LTF2 field 1156 according to embodiments and/or scenarios.

15 is a block diagram illustrating a format of a HEW-SIGA field 1500 according to an embodiment. In some embodiments, HEW-SIGA field(s) 1152 of data unit 1150 or data unit 1400 are formatted as HEW-SIGA field 1500 . In some embodiments, the HEW-SIGA field(s) 1108 is formatted as a HEW-SIGA field 1500 . The HEW-SIGA field 1500 includes a double guard interval 1502 , a first repetition of the HEW-SIGA field 1504 , and a second repetition of the HEW-SIGA field 1506 . In an exemplary embodiment, 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 reliability of decoding of the HEW-SIGA field 1500 . In one embodiment, the auto-correlation of the HEW-SIGA field of the preamble using the format of the HEW-SIGA field 1500 and the preamble using the regular HEW-SIGA field format used in the regular mode, such as the format illustrated in FIG. 13A . The format of the HEW-SIGA field 1500 is used to auto-detect the range extension mode preamble based on a comparison between auto-correlations of the HEW-SIGA field of . In some embodiments, the HEW-SIGA field 1500 has less redundancy compared to the data portion 716 because the additional time domain repetition of the HEW-SIGA field 1500 provides sufficient improvement in decoding performance. It is modulated using redundancy.

16 is a block diagram illustrating an example PHY processing unit for generating regular mode data units using a canonical coding technique according to an embodiment. 1 , in one embodiment, an AP 14 and a 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 range extension data units, such as, for example, one of the data units of Figures 9a, 9b, 10a, or 10b. The PHY processing unit 1600 generally includes a scrambler 1602 that scrambles an information bit stream to reduce the occurrence of long sequences of things or zeros. The FEC encoder 1606 encodes the scrambled information bits to generate encoded data bits. In one embodiment, the FEC encoder 1606 comprises a binary convolutional code (BCC) encoder. In another embodiment, the FEC encoder 1606 includes a binary convolutional encoder followed by a puncturing block. In still other embodiments, the FEC encoder 1606 comprises a low density parity check (LDPC) encoder. Interleaver 1610 receives the encoded data bits and interleaves the bits (ie, changes the order of the bits) to prevent long sequences of adjacent noisy bits from entering the decoder at the receiver. A constellation mapper 1614 maps the interleaved sequence of bits to constellation points corresponding to different subcarriers of an OFDM symbol. More specifically, for each spatial stream, the constellation mapper 1614 converts every bit sequence of length log ₂ (M) to one of the M constellation points.

The output of the constellation mapper 1614 is operated by an inverse discrete Fourier transform (IDFT) unit 1618 that transforms a block of constellation points into a time-domain signal. In embodiments or situations in which the PHY processing unit 1600 operates to generate data units for transmission over multiple spatial streams, the cyclic shift diversity (CSD) unit 1622 intentionally Inserts a cyclic shift in all but one of the spatial streams to prevent beamforming. The output of the CSD unit 1622 outputs, for OFDM symbols, a guard interval that smoothes the edges of each symbol and prepends a circular extension of the OFDM symbol to increase the decay of the spectrum. (GI) insertion and windowing unit 1626 . The output of the GI insert and window 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 range extension mode corresponds to the lowest data rate modulation and coding scheme (MCS) of the regular mode and uses redundancy or repetition of bits to further reduce the data rate in at least some fields or symbols of the data unit. introduced by repetition of For example, in various embodiments and/or scenarios the range extension mode may include redundancy in the data portion of a range extension mode data unit and/or non-legacy signal field or Introduced by repetition of symbols. As an example, according to an embodiment, the canonical mode data units are generated according to a canonical coding technique. In various embodiments, the canonical coding scheme is a series of MCSs, such as MCS0 (binary phase shift keying (BPSK) modulation and coding rate of 1/2) to MCS9 (quadrature amplitude modulation (QAM) and coding rate of 5/6). ) is the selected modulation and coding scheme (MCS: modulation and amplitude modulation), and higher order MCSs correspond to higher data rates. In one such embodiment, the range extension mode data units are generated using a range extension coding technique such as modulation and coding defined by MCS0 with added bit repetition, block encoding, or symbol repetition that further reduces the data rate. do.

17A is a block diagram illustrating an example PHY processing unit 1700 for generating range extension mode data units using a range extension coding technique according to an embodiment. In some embodiments, the PHY processing unit 1700 generates data fields and/or signals of range extension mode data units. 1 , in one embodiment, an AP 14 and a 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 one block of incoming (scrambled) information bits at a time, creates many copies of each block (or each bit within the block), and according to a range extension coding technique. Interleave the resulting bits and output the interleaved bits for further encoding by the FEC encoder 1706 (eg, binary convolutional encoder). In general, each block, after being encoded by the block coder 1704 and by the FEC encoder 1706, according to one embodiment, contains a number of information bits that fill the data tones of a single OFDM symbol. As an example, in one embodiment, the block coder 1704 creates two copies (2x repetitions) of each block of 12 information bits to generate 24 bits included in the OFDM symbol. The 24 bits are then encoded by the FEC encoder 1706 at a coding rate of 1/2 to generate 48 bits modulated (eg, using BPSK modulation) the 48 data tones of the OFDM symbol. As another example, in another embodiment, the block coder 1704 generates 24 bits encoded by the FEC encoder 1706 at a coding rate of 1/2 to generate 48 bits modulated 48 data tones of an OFDM symbol. To do this, we create four copies (4x repetitions) of each block of 6 information bits. As another example, in another embodiment, the block coder 1704 converts the 26 bits encoded by the FEC encoder 1706 at a coding rate of 1/2 to generate 52 bits modulated 52 data tones of the OFDM symbol. to create two copies (2x repetitions) of each block of 13 information bits. 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 data tones of an OFDM symbol.

In some embodiments, the block coder 1704 generates a data (or signal) field with 52 data tones per OFDM symbol, as defined by MCS0 specified in the IEEE 802.11n standard for a 20 MHz channel. A 4x iteration technique is applied. In this case, the block coder 1704, according to one embodiment, creates four copies of each block of 6 information bits to produce 24 bits and then two padding bits (i.e., A number of bits specified by the BCC encoder that encodes 26 bits using a coding rate of 1/2 to generate 52 coded bits to modulate the 52 data tones) and add two bits of predetermined values. (ie, 26 bits for 52 data tones).

In one embodiment, the block coder 1704 uses a “block level” repetition technique in which each block of n bits is repeated m consecutive times. As an example, according to one embodiment, if m is equal to 4 (4x repetitions), the block coder 1704 generates the sequence [C, C, C, C], where C is a block of n bits. In another embodiment, the block coder 1704 uses a "bit level" repetition technique in which each incoming 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 . . .], where b1 is the first bit in the block of bits, b2 is the second bit, and so on. In still other embodiments, the block coder 1704 creates m number of copies of the incoming bits and interleaves the resulting bit stream according to any suitable code. Alternatively, in another embodiment, the block coder 1704 may execute any suitable code, eg, a Hamming block code or 1/2, with a coding rate of 1/2, 1/4, etc. any other block code with a coding rate of 1/4, etc. (eg (1,2) or (1, 4) block code, (12,24) block code or (6, 24) block code; (13,26) block code, etc.) to encode the incoming bits or incoming blocks of bits.

The effective coding rate corresponding to the combination of the coding performed by the coding block coder 1704 and the coding performed by the FEC encoder 1706, according to an embodiment, is the product of the two coding rates. For example, in one embodiment where the block coder 1704 uses 4x repetitions (or a coding rate of 1/4) and the FEC encoder 1706 uses a coding rate of 1/2, the resulting effective coding rate is 1 equal to /8. According to an embodiment, as a result of the reduced coding rate compared to the coding rate used to generate similar regular mode data units, the data rate in the range extension mode is a factor corresponding to the coding rate provided to the block coder 1704 . (e.g., a factor of 2, a factor of 4, etc.)

The block coder 1704 uses the same block coding technique used to generate the data portion of the control mode data unit to generate the signal field of the control mode data unit, in accordance with some embodiments. For example, in one embodiment, the OFDM symbol of the signal field and the OFDM symbol of the data portion, each containing 48 data tones, in this embodiment, for example, the block coder 1704 2x repetition technique is applied to blocks of 12 bits. In another embodiment, the data portion and signal field of the control mode data unit are generated using different block coding techniques. 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 may use a different block size and, in some embodiments, a different coding technique, when operating on the signal field compared to the block size and coding technique used to generate the data portion. use For example, if the long range communication protocol specifies 52 data tones per OFDM symbol of the signal field and 48 data tones per OFDM tones of the data portion, the block coder 1704, according to one embodiment, implements a 2x repetition technique in the signal field. Apply the 2x repetition technique to blocks of 13 bits of , and blocks of 12 bits of the data part.

The FEC encoder 1706 according to an embodiment encodes block coded information bits. In one embodiment, BCC encoding is performed continuously over the entire field being generated (eg, the entire data field, the entire signal field, etc.). Thus, in this embodiment, the information bits corresponding to the field being generated are divided into blocks of a specified size (eg, 6 bits, 12 bits, 13 bits, or any other suitable number of bits). ), each block is processed by a block coder 1704, and the resulting data stream is then provided to an FEC encoder 1706 that sequentially encodes the incoming bits.

Similar to interleaver 1610 of FIG. 16 , in various embodiments, interleaver 1710 changes the order of bits to provide diversity gain and causes consecutive bits in the data stream to be transmitted. Reduces the chance of collapsing in the channel. In some embodiments, however, the block coder 1704 provides sufficient diversity gain so that the interleaver 1710 is omitted. In some embodiments, interleaver 1710 or FEC encoder 1706 provides bits to constellation mapper 1614 for transmission as described above.

In some embodiments, the information bits in the data portion of the range extension mode data unit are padded (ie, many bits of a known value to the information bits such that the data unit occupies, for example, an integer number of OFDM symbols). added). 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 is determined according to padding equations provided in a short range communication protocol (eg, IEEE 802.11a standard, IEEE 802.11n standard, IEEE 802.11ac standard, etc.). In general, these padding equations involve, to some extent, calculating a number of padding bits based on a number of data bits per OFDM symbol (N _DBPS ) and/or a number of coded data bits per symbol (N _CBPS ). accompanying In the range extension mode, according to an embodiment, the number of padding bits before the information bits are block encoded by the block coder 1704 and BCC encoded by the FEC encoder 1706 is based on the number of information bits in the OFDM symbol (e.g., 6 bits, 12 bits, 13 bits, etc.) Thus, the number of padding bits in the range extension mode data unit as a whole is in the corresponding regular mode data (or the corresponding short range data). different from the number of padding bits in the unit). On the other hand, according to an embodiment, the number of coded bits per symbol is the number of coded bits per symbol in a normal mode data unit (or in a corresponding short range data unit), eg, coded bits per OFDM. 24, 48, 52, etc.

17B is a block diagram illustrating an example PHY processing unit 1750 for generating range extension mode data units according to another embodiment. In some embodiments, the PHY processing unit 1750 generates data fields and/or signals of range extension mode data units. 1 , in one embodiment, AP 14 and client station 25 - 1 each include a PHY processing unit such as a PHY processing unit 1750 .

PHY processing unit 1750 is similar to PHY processing unit 1700 of FIG. 17A except that FEC encoder 1706 in PHY processing unit 1750 is replaced by LDPC encoder 1756 . Thus, in this embodiment, the output of the block coder 1704 is provided for further block encoding by the LDPC encoder 1756 . In one embodiment, the LDPC encoder 1756 uses a block code corresponding to a coding rate of 1/2, or a block code corresponding to another suitable coding rate. In the illustrated embodiment, the PHY processing unit 1750 omits the interleaver 1710 because contiguous bits in the information stream are themselves spread by the LDPC code and no further interleaving is required. Additionally, in one embodiment, additional frequency diversity is provided by the LDPC tone remapping unit 1760 . According to an embodiment, the LDPC tone remapping unit 1760 reorders the coded information bits or blocks of coded information bits according to the tone remapping function. Tone remapping function so that consecutive coded information bits or blocks of information bits are mapped onto non-contiguous tones within an OFDM symbol to enable data recovery at the receiver in cases where consecutive OFDM tones are detrimental during transmission (tone remapping function) is defined in general. In some embodiments, the LDPC tone remapping unit 1760 is omitted. In various embodiments, referring again to FIG. 17A , a number of tail bits are typically added to each field of the data unit for proper operation of the FEC encoder 1706 , for example, each encoded After the field is encoded, the BCC encoder ensures that it goes back to the zero state. 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 ). do.

In some embodiments, the signal field of the range extension mode data unit has a different format compared to the signal field format of the regular mode data unit. In some such embodiments, the signal field of the range extension mode data units is shorter compared to the signal field format of the regular mode data unit. For example, according to one embodiment, only one modulation and coding technique is used in the range extension mode so that information (or any information) regarding modulation and coding does not need to be communicated in the range extension mode signal field. Similarly, in one embodiment, the maximum length of the range extension mode data unit is shorter compared to the maximum length of the regular mode data unit and in this case, few bits are required for the length subfield of the range extension mode signal field. As an example, in one embodiment, the range extension mode signal field is formatted according to the IEEE 802.11n standard, but some subfields (eg, low density parity check (LDPC) subfield, space time block coding (STBC) subfield) fields, etc.) are omitted. Additionally or alternatively, in some embodiments, the range extension mode signal field includes a shorter CRC subfield compared to a cyclic redundancy check (CRC) subfield of the regular mode signal field (eg, 8 bits) smaller than those). In general, in the range extension mode according to some embodiments, some signal field subfields are omitted or modified and/or some new information is added.

18A is a block diagram illustrating an example PHY processing unit 1800 for generating range extension mode data units using a range extension coding technique according to another embodiment. In some embodiments, PHY processing unit 1800 generates data fields and/or signals of range extension mode data units. 1 , in one embodiment, AP 14 and client station 25 - 1 each include a PHY processing unit such as a PHY processing unit 1800 .

PHY processing unit 1800 is similar to PHY processing unit 1700 of FIG. 17A except that in PHY processing unit 1800 a block coder 1808 is located after FEC encoder 1806 . Thus, in this embodiment, the information bits are first scrambled by the scrambler 1802, encoded by the FEC encoder 1806 and the FEC coded bits are then replicated or otherwise, the block coder 1808 is block-encoded by In an example implementation of the PHY processing unit 1700 , in one embodiment, processing by the FEC encoder 1806 is performed continuously over the entire field being generated (eg, the entire data portion, the entire signal field). , etc.). Thus, in this embodiment, the information bits corresponding to the field being generated are first encoded by the FEC encoder 1806 and then the BCC coded bits are divided into blocks of a specified size (e.g., 6 bits , 12 bits, 13 bits, or any other suitable number of bits). Each block is then processed by a block coder 1808 . As an example, in one embodiment, the FEC encoder 1806 encodes 12 information bits per OFDM symbol using a coding rate of 1/2 to generate 24 BCC coded bits and converts the BCC coded bits to a block coder ( 1808). In one embodiment, the block coder 1808 generates two copies of each incoming block according to a range extension coding scheme coding scheme and interleaves the generated bits to generate 48 bits to be included in the OFDM symbol. In one such embodiment, the 48 bits correspond to 48 data tones generated using a size 64 fast Fourier transform (FFT) in IDFT processing unit 1818 . As another example, in another embodiment, the FEC encoder 1806 encodes 6 information bits per OFDM symbol using a coding rate of 1/2 to generate 12 BCC coded bits and converts the BCC coded bits to a block coder ( 1808). In one embodiment, the block coder 1808 generates two copies of each incoming block according to a range extension coding technique and interleaves the generated bits to generate 24 bits to be included in the OFDM symbol. In one such embodiment, the 24 bits correspond to 24 data tones generated using a fast Fourier transform (FFT) of size 32 in IDFT processing unit 1818 .

Similar to the block coder 1704 of FIG. 17A , the range extension coding technique used by the block coder 1808 to generate the signal field of the range extension mode data unit according to an embodiment is the data portion of the range extension mode data unit. The same or different from the range extension coding technique used by the block coder 1808 to generate In various embodiments, the block coder 1808 may use a “block level” iteration scheme or a “bit level” iteration scheme as discussed above with respect to block coder 1704 of FIG. 17A . to implement Similarly, in another embodiment, the block coder 1808 creates m number of copies of the incoming bits and interleaves the resulting bit stream according to an appropriate code or otherwise uses any suitable code, e.g., 1/2, A Hamming block code having a coding rate of 1/4, etc. or any other block code having a coding rate of 1/2, 1/4, etc. (eg (1,2) or (1, 4) Encode incoming bits or incoming blocks of bits using a block code, (12,24) block code or (6, 24) block code, (13,26) block code, etc.). According to one embodiment, the effective coding rate for the data units generated by the PHY processing unit 1800 is the coding rate used by the FEC encoder 1806 and the repetition used by the block coder 1808 . is the product of the number (or coding rate) of

In one embodiment, the block coder 1808 provides sufficient diversity gain so that additional interleaving of the coded bits is not required, and the interleaver 1810 is omitted. One advantage of omitting the interleaver 1810 is that in this case OFDM symbols with 52 data tones can be generated using 4x or 6x repetition techniques, even if in some such situations the number of data bits per symbol is not an integer. . For example, in one such embodiment, the output of the FEC encoder 1806 is split into blocks of 13 bits, each block four times (or at a rate of 1/4) to generate 52 bits to be included in the OFDM symbol. block encoded) is repeated. In this case, if the FEC encoder 1806 uses a coding rate of 1/2, the number of data bits per symbol equals 6.5. In an exemplary embodiment using 6x repetition, the FEC encoder 1806 encodes the information bits using a coding rate of 1/2 and the output is split into blocks of four bits. The block coder 1808 iterates over each four-bit block six times (or block-encodes each block using a coding rate of 1/6), and four padding bits to generate 52 bits to be included in the OFDM symbol. (padding bits) are added.

As in the example of PHY processing unit 1700 of FIG. 17A described above, if padding is used by PHY processing unit 1800, the number of data bits per symbol (N _DBPS ) used for padding bit calculation is OFDM The actual number of non-redundant data bits in the symbol (eg, 6 bits, 12 bits, 13 bits, or any other suitable number of bits in the example above). The number of coded bits per symbol (N _CBPS ) used in the padding bit calculation is equal to the number of bits actually included in the OFDM symbol (eg, 24 bits, 48 bits, 52 bits included in the OFDM symbol) , or any other suitable number of bits).

Also in the example of the PHY processing unit 1700 of FIG. 17 , a number of tail bits are typically inserted into each field of the data unit for proper operation of the FEC encoder 1806 , e.g., each encoded After the field of is encoded, it ensures that the BCC encoder goes back to the zero state. 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 (eg, performed after processing by the block coder 1704 ). . Similarly, in the case of a signal field according to one embodiment, 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 repetition scheme (or other block codes with a coding rate of 1/4), the FEC encoder 1806 uses a coding rate of 1/2, and the signal field contains 24 information bits (including tail bits), the 24 signal field bits being BCC encoded to produce 48 BCC encoded bits, then each of 12 bits for further encoding by the block coder 1808 . It is divided into four blocks. Thus, in this embodiment, the signal field is transmitted on four OFDM symbols and each of the symbols contains 6 information bits of the signal field.

Moreover, in some embodiments, the PHY processing unit 1800 generates OFDM symbols with 52 data tones according to the IEEE 802.11n standard or MCS0 specified in the IEEE 802.11ac standard and the block coder 1808 uses a 4x repetition technique. do. In some such embodiments, redundant padding is used to ensure that the resulting encoded data stream to be included within an OFDM symbol contains 52 bits. In one such embodiment, padding bits are added to the coded information bits after the bits have been processed by the 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, PAPR reduction unit 1809 flips bits in some or all repeated blocks to reduce or exclude occurrences of identical bit sequences at different frequency positions within an OFDM symbol, thereby flipping the output signal reduce the peak-to-average power ratio of In general, bit flipping involves replacing bit value zero with bit value one and bit value one with bit value zero. According to one embodiment, the PAPR reduction unit 1809 implements bit flipping using an XOR operation. For example, in one embodiment using 4x repetition of a block of coded bits, if the block of coded bits to be included in OFDM symbols is denoted by C and if C' = C XOR 1 (ie, the bit flipped block C), then some possible bit sequences at the output of PAPR reduction unit 1809 according to some embodiments are [CC' C' C'], [C' C' C' C], [CC' C C'], [CCC C'], and the like. In general, any combination of blocks with flipped bits and blocks with non-flipped bits can be used. In some embodiments, the PAPR unit 1809 is omitted.

18B is a block diagram illustrating an example PHY processing unit 1850 for generating range extension mode data units according to another embodiment. In some embodiments, the PHY processing unit 1850 generates a signal and/or data fields of range extension mode data units. 1 , in one embodiment, AP 14 and client station 25 - 1 each include a PHY processing unit such as a PHY processing unit 1850 .

PHY processing unit 1850 is similar to PHY processing unit 1800 of FIG. 18 except that FEC encoder 1806 in PHY processing unit 1850 is replaced by LDPC encoder 1856 . Thus, in this embodiment, the information bits are first encoded by the LDPC encoder 1856 and the LDPC coded bits are then copied or otherwise block encoded by the block coder 1808 . In one embodiment, the LDPC encoder 1856 uses a block code corresponding to a coding rate of 1/2, or a block code corresponding to another suitable coding rate. In the illustrated embodiment, the PHY processing unit 1850 omits the interleaver 1810 because contiguous bits in the information stream are themselves spread by the LDPC code and no further interleaving is required, according to one embodiment. Additionally, in one embodiment, additional frequency diversity is provided by the LDPC tone remapping unit 1860 . According to an embodiment, the LDPC tone remapping unit 1860 reorders the coded information bits or blocks of coded information bits according to a tone remapping function. Tone remapping function so that consecutive coded information bits or blocks of information bits are mapped onto non-contiguous tones within an OFDM symbol to enable data recovery at the receiver in cases where consecutive OFDM tones are detrimental during transmission This is defined as a whole. In some embodiments, the LDPC tone remapping unit 1860 is omitted.

19A is a block diagram illustrating an example PHY processing unit 1900 for generating range extension mode data units according to another embodiment. In some embodiments, the PHY processing unit 1900 generates data fields and/or signals of range extension mode data units. 1 , in one embodiment, an AP 14 and a client station 25 - 1 each include a PHY processing unit such as a PHY processing unit 1900 .

PHY processing unit 1900 is similar to PHY processing unit 1800 of FIG. 18A except that block coder 1916 is located behind constellation mapper 1914 in PHY processing unit 1900 . Thus, 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 otherwise block encoded by the block coder 1916. do. According to one embodiment, processing by the FEC encoder 1906 is performed continuously over the entire field being generated (eg, the entire data field, the entire signal field, etc.). In this embodiment, the information bits corresponding to the field being generated are first encoded by the FEC encoder 1806 and then the BCC coded bits are mapped to the constellation symbols by the constellation mapper 1914 . The constellation symbols are then divided into blocks of a specified size (eg, 6 symbols, 12 symbols, 13 symbols, or any other suitable number of symbols) and then each block is (1916). As an example, in one embodiment using 2x repetition, constellation mapper 1914 generates 24 constellation symbols and block coder 1916 generates 48 symbols corresponding to 48 data tones of an OFDM symbol ( Create two copies of 24 symbols (as specified in the IEEE 802.11a standard, for example). As another example, in one embodiment using 4x repetition, constellation mapper 1914 generates 12 constellation symbols and block coder 1916 generates 48 symbols corresponding to 48 data tones of an OFDM symbol ( For example, four copies of the 12 constellation symbols are created (as specified in the IEEE 802.11a standard). As another example, in one embodiment using 2x repetition, constellation mapper 1914 generates 26 constellation symbols and block coder 1916 generates 52 symbols corresponding to 52 data tones of an OFDM symbol. Repeat the 26 symbols (eg, as specified in the IEEE 802.11n standard or the IEEE 802.11ac standard) (ie, create two copies of the 26 symbols). In general, in various embodiments and/or scenarios, block coder 1916 generates any suitable number of copies of blocks of incoming constellation symbols and interleaves the generated symbols according to any suitable coding technique. Similar to block coder 1704 of FIG. 17A and block coder 1808 of FIG. 18A, by block coder 1916 to generate a signal field (or signal fields) of a range extension mode data unit according to an embodiment. The range extension coding scheme used is the same as or different from the range extension coding scheme used by the block coder 1916 to generate the data portion of the range extension mode data unit. According to an 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 repetitions used by the block coder 1916 (or coding rate).

Since, in this case, redundancy is introduced after the information bits are mapped to constellation symbols, according to one embodiment, each OFDM symbol generated by the PHY processing unit 1900 is an OFDM symbol contained within regular mode data units. It contains fewer non-redundant data tones compared to the data tones. Thus, the interleaver 1910 operates on fewer tones per OFDM symbol compared to the interleaver used in regular mode (eg, interleaver 1610 in FIG. 16 ), or the interleaver used when generating the corresponding short range data unit. designed to do For example, in one embodiment with 12 non-redundant data tones per OFDM symbol, interleaver 1910 determines the number of columns (N _col ) 6 and the number of rows (N _row ) 2* the number of bits per subcarrier ( It is designed using N _bpscs ). In another example embodiment with 12 non-redundant data tones per OFDM symbol, the interleaver 1910 is designed using N _col 4 and N _row 3*N _bpscs . In other embodiments, other interleaver parameters are used for the interleaver 1910 than the interleaver parameter used in the regular mode. Alternatively, in one embodiment, the block coder 1916 provides sufficient diversity gain so that additional interleaving of the coded bits is not required, and the interleaver 1910 is omitted. In this case, as in the representative embodiment using the PHY processing unit 1800 of FIG. 18A , OFDM symbols with 52 data tones are performed using a 4x or 6x repetition scheme, even if the number of data bits per symbol in some such situations is not an integer in some such situations. can be created using

If padding is used by the PHY processing unit 1900, as in the example embodiment of the PHY processing unit 1700 of FIG. 17A or the PHY processing unit 1800 of FIG. 18 described above, used for calculating the padding bit. The number of data bits per symbol that becomes N _DBPS is the actual number of non-redundant data bits in the OFDM symbol (eg, 6 bits, 12 bits, 13 bits in the example above, or any other suitable number of bits). The number of coded bits per symbol (N _CBPS ) used in padding bit calculations is, in this case, the number of bits in a block of constellation symbols processed by block coder 1916 (e.g., 12 bits, 24 bits, 26 bits, etc.) equal to the number of non-redundant bits included in the OFDM symbol.

In some embodiments, PHY processing unit 1900 generates OFDM symbols with 52 data tones according to MCS0 specified in IEEE 802.11n standard or IEEE 802.11ac standard and block coder 1916 uses a 4x repetition technique. In some such embodiments, redundant padding is used to ensure that the resulting encoded data stream to be included within an OFDM symbol contains 52 bits. In one such embodiment, padding bits are added to the coded information bits after the bits have been processed by the block coder 1808 .

In the embodiment of FIG. 19 , 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 modulated with the repeated constellation. For example, in one embodiment the added phase shift is 180 degrees. A 180 degree phase shift corresponds to a sign flip of bits modulating the data tones on which the phase shifts are implemented. In another embodiment, the PAPR reduction unit 1917 adds another 180 degree phase shift (eg, a 90 degree phase shift or any other suitable phase shift). As an example, in one embodiment using 4x repetition, if a block of 12 constellation symbols to be included in OFDM symbols is denoted as C and simple block repetition is performed, the resulting sequence is [C C C C]. In some embodiments, PAPR reduction unit 1917 introduces a sign flip (ie, -C) or a 90 degree phase shift (ie, j*C) for some repeated blocks. In some such embodiments, the resulting sequence is, for example, [C -C -C -C], [-C -C -C -C], [C -CC -C], [CCC -C], [ C j*C, j*C, j*C], or any other combination of C, -C, j*C, and -j*C. In general, any suitable phase shift may be introduced into any repeated block in various embodiments and/or scenarios. In some embodiments, the PAPR reduction unit 1809 is omitted.

In some embodiments, PHY processing unit 1900 generates OFDM symbols with 52 data tones according to MCS0 specified in IEEE 802.11n standard or IEEE 802.11ac standard and block coding 1916 uses a 4x repetition technique. In some such embodiments, redundant pilot tones are inserted to ensure that the resulting number of data and pilot tones in an OFDM symbol is equal to 56 specified in the short range communication protocol. As an example, in one embodiment, six 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 are 48 data tones generated by being modulated with 12 data tones and then repeated four times. Four pilot tones are added as specified in the IEEE 802.11n standard and 4 redundant pilot tones are added to generate 56 data and pilot tones.

19B is a block diagram illustrating an example PHY processing unit 1950 for generating range extension mode data units according to another embodiment. In some embodiments, PHY processing unit 1950 generates a signal and/or data fields of range extension mode data units. 1 , in one embodiment, the AP 14 and the client station 25 - 1 each include a PHY processing unit such as a PHY processing unit 1950 .

PHY processing unit 1950 is similar to PHY processing unit 1900 of FIG. 19 except that FEC encoder 1906 in PHY processing unit 1950 is replaced by LDPC encoder 1956 . Thus, in this embodiment, the LDPC encoded information bits are mapped to constellation symbols by a constellation mapper 1914 and the constellation symbols are then duplicated or otherwise block encoded by a block coder 1916 . . In one embodiment, the LDPC encoder 1956 uses a block code corresponding to a coding rate of 1/2, or a block code corresponding to another suitable coding rate. In the illustrated embodiment, the PHY processing unit 1950 omits the interleaver 1910 because contiguous bits in the information stream are themselves spread by the LDPC code and no further interleaving is required, according to one embodiment. Additionally, in one embodiment, additional frequency diversity is provided by the LDPC tone remapping unit 1960 . According to an embodiment, the LDPC tone remapping unit 1960 reorders the coded information bits or blocks of coded information bits according to a tone remapping function. Tone remapping function so that consecutive coded information bits or blocks of information bits are mapped onto non-contiguous tones within an OFDM symbol to enable data recovery at the receiver in cases where consecutive OFDM tones are detrimental during transmission This is defined as a whole. In some embodiments, the LDPC tone remapping unit 1960 is omitted.

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

21 is a flow diagram of an exemplary method 2100 for generating a data unit according to one embodiment. Referring to FIG. 1 , method 2100 is implemented, in one embodiment, by network interface 16 . For example, in one such embodiment, the PHY processing unit 20 is configured to implement the method 2100 . According to another embodiment, MAC processing 18 is also configured to implement in at least a portion of method 2100 . With continued reference to FIG. 1 , in another embodiment, method 2100 is implemented by network interface 27 (eg, PHY processing unit 29 and/or MAC processing unit 28 ). In other embodiments, method 2100 is implemented by 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 technique described above with respect to block coder 1704 of FIG. 17 . At block 2104 , the information bits are encoded using an FEC encoder, such as, for example, the FEC encoder 1706 of FIG. 17A or the LDPC encoder 1756 of FIG. 17B . At block 2106, the 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 for including OFDM symbols is generated.

In one embodiment, as illustrated in FIG. 21 , the information bits are first encoded using a block encoder (block 2102 ) and the block coded bits are then encoded using an FEC encoder, for example as described above with respect to FIG. 17A , as illustrated in FIG. 21 . (block 2104). In another embodiment, the order of blocks 2102 and 2104 is interchanged. Thus, in this embodiment, for example, As such, the information bits are first FEC encoded and the FEC encoded bits are encoded according to a block coding scheme. In other embodiments, block 2102 is located 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 the constellation symbols are then mapped to the constellation symbols at block 2102, e.g., as described above with respect to FIG. 19A. ) is encoded according to block coding or iterative techniques.

In various embodiments, the range extension coding technique uses a reduced size fast Fourier transform (FFT) technique that outputs a reduced number of constellation symbols that are repeated over the entire large bandwidth to improve range 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-FFT mode). The 32 sub-carriers correspond to the 10 MHz sub-band of the entire 20 MHz bandwidth. In this example, the constellation symbols are repeated over the entire bandwidth of 20 MHz to provide redundancy of the constellation symbols. In various embodiments, the reduced size FFT technique is used in combination with the bit-wise and/or symbol duplication techniques described above with respect to Figures 17-19.

In some embodiments where additional bandwidth is available, such as 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz, etc., 32 subcarriers are repeated across each 10 MHz subband of the full bandwidth. For example, in another embodiment, the 32-FFT mode corresponds to a 5 MHz subband of the entire 20 MHz bandwidth. In this embodiment, multiple constellations are repeated 4x across the entire 20 MHz bandwidth (ie, in each 5 MHz subband). Accordingly, the receiving device combines multiple constellations to improve decoding reliability of the constellations. In some embodiments, the modulation of different 5 or 10 MHz sub-bandwidth signals is rotated by different angles. For example, in one embodiment, the first subband is rotated 0-degrees, the second subband is rotated 90-degrees, the third sub-band is rotated 180-degrees, and the fourth sub-band is 270 degrees rotated. - is also rotated. In other embodiments, different suitable rotations are used. Different phases of the 20 MHz sub-band signals, in at least some embodiments, result in a reduced peak-to-average power ratio (PAPR) of OFDM symbols within a data unit.

22A is a diagram of a 20 MHz full bandwidth with 2x repetitions with a range extension data unit with 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, respectively. 22B is a diagram of a 40 MHz full bandwidth with 4x repetitions of a range extension data unit with a 10 MHz subband according to one embodiment. As shown in Fig. 22B, each subband of 10 MHz is rotated individually by rotations r1, r2, r3, and r4. 22C is a diagram of an example tone plan 2230 for a 32-FFT mode corresponding to a 10 MHz subband, according to one embodiment. Tone plan 2230 includes 32 total tones with 24 data tones, 2 pilot tones at indices +7 and -7, 1 direct current tone, and 5 guard tones as shown in FIG. 22 . In embodiments where the reduced size FFT technique is used, the corresponding tone plan, if present, is used for the HEW-LTF field. In other embodiments where the reduced size FFT technique is used but the HEW-LTF field is not present, the L-LTF field 704 is an additional ±1 sign for pilot tones to the corresponding indices of the modified tone plan. modified to include 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, ±1 signs are removed from the L-LTF tone plan on tones -2, -1, 1, and 2 within the 20 MHz bandwidth. Similar changes apply for all bandwidths of 40 MHz, 80 MHz, 160 MHz, etc.

23 is a diagram of an example data unit 2300 in which the laser extension mode is used for the preamble 2301 of the data unit according to an embodiment. In some embodiments, the preamble 2301 indicates both a regular mode and a range extension mode. In this embodiment, another method for distinguishing between the range extension mode and the regular mode is used, such as those described above with respect to Figures 9, 10, and 11 .

Data unit 2301 is generally similar to data unit 1150 of FIG. 11B , except that the preamble 2301 of the data unit 2300 is formatted differently than the preamble 1151 of the data unit 1101, and has the same number Contains elements numbered as . 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 a range extension mode preamble instead of a regular mode preamble. In one embodiment, the preamble 2301 comprises a modified long training field M-LTF 2304 and a modified long training field M-LTF 2304 instead of the L-LTF 704 and L-SIG 706 respectively compared to the data unit 1151 , respectively. contains a signal field M-SIG 2306 . In one embodiment, the preamble 2301 includes an L-STF 702, a double guard interval, followed by two repetitions of a long training sequence modified as M-LTF 2304, a normal guard interval, and a modified signal field M -Includes SIG. In some embodiments, the preamble 2301 further includes one or more first HEW signal fields (HEW-SIGAs) 1152 . In one embodiment, the preamble 2301 further includes one or more second L-SIG(s) 1154 following the M-Sig field 2306 . In some embodiments the second L-SIG(s) 1154 is followed by a second L-LTF field (L-LTF2) 1156 . In other embodiments, the preamble 2301 omits the L-SIG(s) 1154 and/or the L-LTF2 1156 . In some embodiments, the preamble 2301 also includes a HEW-STF 1158 , one or more HEW-LTF fields 1160 , and a second HEW signal field (HEW-SIGB) 1162 . In other embodiments, the preamble 2301 omits the HEW-STF 1158 , HEW-LTF(s) 1160 and/or HEW-SIGB 1162 . In one embodiment, data unit 2300 also includes data portion 716 (not shown in FIG. 23 ). In some embodiments, HEW signal fields (HEW-SIGAs) 1152 are modulated using the same range extension coding technique as data field 716 .

In various embodiments, M-LTF 2304 corresponds to L-LTF 704 multiplied by a predetermined sequence (eg, a polarization code). For example, using the index i, the i-th constellation symbol of the L-LTF 704 to obtain the M-LTF 2304 as shown in Equation 1 is the i-th value of the predetermined sequence ( For example, it is multiplied by ±1):

(방정식 1)

(Equation 1)

where 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:

(방정식 2)

(Equation 2)

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

In one embodiment, each of the predetermined sequence and the modified long training sequence has a length greater than or equal to the sum of the number of data tones and the number of pilot tones. As described above with respect to the tone plan 2230 for the 32-FFT mode corresponding to the 10 MHz subband, if the HEW-STF and/or HEW-LTF fields are not present in the range extension preamble, the receiver It relies on the L-LTF field for demodulation of the fields. In one embodiment, the tone plan is mismatched between 20 MHz L-LTF and 10 MHz 32-FFT mode for missing tones (eg , tones -29, -27, +27, and + for a total of 58 tones). 29 ) is corrected by inserting +1 or -1 signs into the L-LTF.

24 is a block diagram illustrating an example PHY processing unit 2400 for generating range extension mode data units according to another embodiment. In some embodiments, the PHY processing unit 2400 generates a signal and/or training fields of range extension mode data units. 1 , in one embodiment, AP 14 and client station 25 - 1 , each include a PHY processing unit such as a PHY processing unit 2400 .

PHY processing unit 2400 is similar to PHY processing unit 1700 of FIG. 17A except that a tone multiplier 2404 in PHY processing unit 2400 is located behind constellation mapper 1614 . In some embodiments, tone multiplier 2404 provides i) modified constellation symbols for the L-Sig field (ie, M-SIG 2306) and ii) the L-LTF field of the range extension mode data unit ( That is, generate a modified long training sequence for M-LTF 2304).

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

In one embodiment, tone multiplier 2404 receives constellation symbols for data included in L-SIG 706 from constellation mapper 1614 and constellation symbols for a pilot tone from pilot tone generator 2408 . receive them Accordingly, in one embodiment the M-SIG 2306 output from tone multiplier 2404 includes transformed constellation symbols for pilot tones and data tones to be converted by IDFT 1618 to a time-domain signal.

In some embodiments, the receiver device decodes the M-SIG 2306 using, for example, channel estimates based on the M-LTF 2304 . In this example, since both L-LTF 704 and L-SIG 706 have been multiplied by a predetermined sequence, the legacy receiver device performs multiplication as part of the channel estimation process or auto-correlation process. effectively omitted. In one embodiment, the receiving device determines that the preamble LTF field in the preamble (eg, M-LTF 2304 or L-LTF 704 ) does not multiply with the predetermined sequence and with the predetermined sequence L-LTF Corresponds to range extension mode preamble 2400 or normal mode preamble 1101 by detecting whether it is generated with a predetermined sequence based on auto-correlation of the field or not multiplied with a predetermined sequence (e.g., multiplied) decide whether to In one embodiment, the receiving device performs a first auto-correlation of the LTF with L-LTF 704 , performs a second auto-correlation of the LTF with M-LTF 2304 , and auto-correlation Comparison of the results is performed. In one embodiment, if the auto-correlation to the M-LTF 2304 produces a larger result compared to the result of the auto-correlation to the L-LTF 704, then the receiving device determines that the preamble is the extended mode preamble. Decide which corresponds to (2300). On the other hand, in one embodiment if the auto-correlation of the LTF to the L-LTF 704 produces a larger result compared to the result of the auto-correlation to the M-LTF 2304, then the receiving device sends the preamble It determines which one corresponds to the regular mode preamble (1101). In some embodiments, the receiver device performs auto-correlation in the frequency domain according to Equation 3:

(방정식 3)

(Equation 3)

where y _i is the last received and averaged L-LTF sequence, and L _i is the transmitted L-LTF sequence or modified long training sequence M-LTF belonging to IEEE 802.11a/n/ac. For example, L _i is C _i * L-LTF _i for the range extension mode or L-LTF _i for the regular mode. In some scenarios, cross-correlation of successive tones generally removes channel effects and frequency domain match filtering finds the most likely transmitted sequence. In some embodiments, the receiver device uses the channel estimate from the M-LTF to decode additional fields of the data unit (ie, HEW-SIG and/or data fields). In some scenarios, the values of the predetermined sequence corresponding to the pilot tones are all one, allowing phase tracking on the pilot tones.

In some embodiments, OFDM modulation with reduced tone spacing is used with the same size FFT to reduce data rate in range extension mode. For example, the regular mode for a 20 MHz bandwidth OFDM data unit uses a 64-point fast Fourier transform (FFT) that results in 64 OFDM tones, whereas the range extension mode uses a factor of 2 that results in 128 OFDM tones in the same bandwidth. Tone spacing reduced by the factor is used. In this case, the tone spacing in range extension mode OFDM symbols is reduced by a factor of 2 compared to regular mode OFDM symbols while using the same 64-point FFT, 2x increased symbol duration, and 2x increased guard interval ( 1/2), then the symbols are repeated in the remaining bandwidth. As another example, the regular mode for a 20 MHz bandwidth OFDM data unit uses a 64-point fast Fourier transform (FFT) resulting in 64 OFDM tones, while the range extension mode results in 256 OFDM tones in the same bandwidth 20 MHz OFDM Use a ¼ reduced tone spacing for data units. In this case, the tone spacing in range extension mode OFDM symbols is reduced by a factor of 4 compared to regular mode OFDM symbols while using 4x increased symbol duration, and 4x increased guard interval (1/4). In such embodiments, a long GI duration of, for example, 1.6 μs is used. However, in one embodiment the duration of the information portion of the range extension mode OFDM symbol is increased (eg, from 3.2 μs to 6.4 μs), and the percentage of total OFDM symbols duration to GI portion duration remains the same. do. Thus, in this case, an efficiency loss is avoided due to a longer GI symbol in at least some embodiments. In various embodiments, the term “long guard interval” as used herein encompasses an increased duration of the guard interval as well as a reduced OFDM tone interval that effectively increases the duration of the guard interval. In other embodiments, the tone spacing is reduced, the guard spacings are increased, and the symbol duration is increased according to factors 6, 8, or other suitable values. In some embodiments, variations in tone spacing, guard spacings, and symbol duration are used in combination with block coding or symbol repetition as described above.

The full signal bandwidth of the data units for the range extension mode is 20 MHz in some embodiments. For example, increased signal bandwidth will not further increase range or improve SNR performance. In some embodiments, the range extension mode is configured to use an FFT size of up to 512 points. In this embodiment, if the tone-spacing is reduced by a factor of 4 for the range extension mode, then the total bandwidth for the 512 FFT is 40 MHz and thus the range extension mode uses up to 40 MHz signal bandwidth.

In other embodiments, the range extension mode is configured for up to the largest available signal bandwidth (eg, 160 MHz). In various embodiments, for example, the ½ tone spacing is 64 FFT for the 10 MHz band, 128 FFT for the 20 MHz band, 256 FFT for the 40 MHz band, 512 FFT for the 80 MHz band, and the 160 MHz band. corresponds to 1024 FFT. In some embodiments, a reduced tone spacing is used in combination with a smaller FFT size. In various embodiments, shorter guard intervals are reduced, for example, where the normal guard interval has a duration equal to 25% of the duration of the OFDM symbol and the short guard interval has a duration equal to 1/9th of the OFDM symbol. Used with the specified tone spacing.

In some embodiments, the range extension mode uses a smaller tone spacing (ie, ½, ¼, etc.). In such an embodiment, the same FFT size, for example, 1/2 tone spacing represents a smaller bandwidth corresponding to 64 FFTs for the 10 MHz band. In one embodiment, the tone plan within the same FFT size is the same for both range extension mode and regular mode, e.g., 64 FFTs in range extension mode are the same tone plan as 64 FFTs for 20 MHz in IEEE 802.11ac. (tone plan) is used. 25A is a diagram of an example 20 MHz full bandwidth with ½ tone spacing according to one embodiment. In this case, the indices for the original DC tones of the legacy tone plan for each 64FFT are now in the middle of the 10 MHz subband instead of in the middle of the total 20 MHz bandwidth, and the indices for the original guard tones are the true DC tone close to In some embodiments where the band used for the range extension mode data unit is less than 20 MHz, the smallest signal bandwidth is the range extension mode or regular because the indices will not overlap with “true DC tone” Since it is 20 MHz for the mode, the non-legacy tone plan contains additional data or pilot tones in indices to the original DC tones. In some embodiments, the non-legacy tone plan includes additional data tones instead of guard tones at the edges of the legacy tone plan to maintain the same number of populated tones.

In other embodiments, when the tone spacing is reduced, the influence from the direct current offset and carrier frequency offset (CFO) becomes greater compared to the normal mode. 25B is a diagram of an example 20 MHz full bandwidth with ½ tone spacing according to one embodiment. In some embodiments, the additional zero tones are defined closer to the direct current tone of the band for the non-legacy tone plan of the range extension mode compared to a legacy tone plan of the same FFT size in the regular mode. In various embodiments, for example, only in advance when the FFT size is greater than or equal to 128 with tone spacing reduced by ½, or when the FFT size is greater than or equal to 256 with tone spacing reduced by ¼. Additional zero tones are defined above the determined FFT size and/or tone spacing. In some embodiments, for example, an increased number of guard tones are added to the range extension mode to maintain the same absolute guard spacing (eg, absolute frequency spacing) at the band edges compared to the legacy tone plan in the regular mode. Used for non-legacy tone plans for . In this case, the total number of data tones and pilot tones in the non-legacy tone plan is less than the legacy tone plan. In some examples, the same absolute guard spacing facilitates filter designs. In some embodiments, the PHY parameters for the FEC interleaver and/or LDPC tone mapper are the non-legacy tones, for example, if the total number of data tones for the non-legacy tone plan is different from the same FFT size of the regular mode. It is redefined for the number of data tones in the plan.

26A is a diagram of a non-legacy tone plan 2600 for range extension mode with size 64 FFT and ½ tone spacing, according to one embodiment. In the non-legacy tone plan 2600 , additional guard tones are included compared to the legacy tone plan for the regular mode (ie, guard tones -28, -27, +27, +28). In some embodiments, 64 FFTs are packed into DC tones along with pilot tones or data tones. 26B is a diagram of a non-legacy tone plan 2601 for range extension mode with size 128 FFT and ½ tone spacing according to one embodiment. In the non-legacy tone plan 2601, additional guard tones (ie, guard tones -58, -57, +57, +58) and additional DC tones (ie, DC tones -2, -1, 0, 1, 2) are included. 26C is a diagram of a non-legacy tone plan 2602 for range extension mode with size 256 FFT and ½ tone spacing, according to one embodiment. In the non-legacy tone plan 2602 , compared to the legacy tone plan for the regular mode, additional guard tones (ie, guard tones -122, -121, +121, +122) and additional DC tones (ie, DC tones -2, -1, 0, 1, 2) are included. In other embodiments, additional guard tones and/or DC tones are added to the non-legacy tone plans for the range extension mode compared to the regular mode.

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

At block 2702, first OFDM symbols for the data field are generated. In various embodiments, generating the OFDM symbols at block 2702 comprises generating OFDM symbols of the data portion according to one of a range extension coding scheme corresponding to a range extension mode or a canonical coding scheme corresponding to the regular mode. includes In one embodiment, the range extension coding technique includes the range extension coding techniques described above with respect to FIG. 10 (eg, reduced tone spacing). In another embodiment, the range extension coding technique includes the range extension coding techniques described above with respect to FIGS. 17-20 (eg, bit-wise repetition or symbol repetition). In another embodiment, the range extension coding technique includes the range extension coding techniques described above with respect to FIG. 22 (eg, data unit repetition). In another embodiment, the range extension coding scheme comprises an appropriate combination of the range extension coding schemes described above with respect to FIGS. 10 , 17-20 and 22 .

In one embodiment, generating OFDM symbols for a data portion of a PHY data unit according to a range extension coding scheme comprises: a forward error correction (FEC) encoder (eg, an FEC encoder) to obtain a plurality of encoded bits. encoding the plurality of information bits using (1706), (1806), or (1906); mapping the plurality of encoded bits to a plurality of constellation symbols, eg, using a constellation mapper (1614) or (1914); generating OFDM symbols including the plurality of constellation symbols using, for example, IDFT (1618) or (1818). In one embodiment, generating OFDM symbols comprises: i) encoding a plurality of information bits according to a block coding scheme (e.g., using block coder 1704), ii) according to a block coding scheme encoding the plurality of encoded bits (e.g., using a block coder 1808), or iii) encoding the plurality of constellation symbols according to an encoding block coding technique (e.g., using a block coder (e.g., a block coder ( 1916)). In another embodiment, for example, as described above with respect to FIG. 22, generating OFDM symbols for the data field comprises a plurality of constellation symbols within a first bandwidth portion of the channel bandwidth and a second portion of the channel bandwidth. and generating OFDM symbols of the data field including copies of the plurality of constellation symbols within the bandwidth portion. In a further embodiment, copies of a plurality of constellation symbols comprising a predetermined phase shift are generated.

At block 2704, a preamble of the data unit is generated. The preamble generated at block 2704 is generated to indicate whether the data portion of at least the data unit generated at block 2702 was generated using a range extension coding technique or a canonical coding technique. In various embodiments and/or scenarios, preambles 701 ( FIGS. 9a , 10a ), 751 ( FIGS. 9b , 10b ), 1101 ( FIGS. 11a ), 1151 ( FIG. 11b ) ), or 1401 ( FIG. 14A ) is generated at block 1604 . In other embodiments, other suitable preambles are generated at block 2704 .

In one embodiment, the preamble is generated to have i) a first portion indicating the duration of the PHY data unit and ii) a second portion indicating whether at least some OFDM symbols of the data portion have been generated according to a range extension coding scheme. In a further embodiment, the preamble is such that a first portion of the preamble is decodable by a receiver device that does not conform to a first communication protocol (eg, a HEW communication protocol) but conforms to a second communication protocol (eg, a legacy communication protocol). A first portion of is formatted to determine the duration of the PHY data unit based on the first portion of the preamble.

In one embodiment, the preamble generated at block 2704 includes a CI indication configured to indicate whether at least the data portion was generated using a range extension coding technique or a canonical coding technique. In one embodiment, the CI indication comprises one bit. In one embodiment, in addition to the data portion, a portion of the preamble is generated using a coding technique indicated by the CI indication. In another embodiment, the preamble generated at block 2704 is formatted such that the receiving device can automatically detect (eg, without decoding) whether the preamble corresponds to a regular mode preamble or a range extension mode preamble. In one embodiment, sensing of the range extension mode preamble signals to the receiving device that at least the data portion was generated using a range extension coding technique.

In one embodiment, generating the preamble comprises generating a second portion of the preamble comprising second OFDM symbols for i) a short training field according to a first communication protocol and ii) at least one copy of the short training field. and generating third OFDM symbols for i) a long training field according to the first communication protocol and ii) at least one copy of the long training field. In a further embodiment, the OFDM symbols for the data portion, the second OFDM symbols, and the third OFDM symbols have the same tone plan separate from the tone plan for the first portion of the preamble.

In another embodiment, block 2704 includes generating a first signal field for a PHY data unit according to a second communication protocol (eg, a legacy communication protocol) and at least some OFDM symbols in the data field are in a range extension mode. generating a second signal field as a copy of the first signal field to indicate that it has been generated according to 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 used by a receiver device conforming to the first communication protocol as an additional training field possible. In another embodiment, the first signal field and the second signal field are decodable in combination by a receiver device conforming to the first communication protocol to increase decoding reliability of the first signal field and the second signal field.

In one embodiment, the first portion of the preamble comprises i) a legacy short training field conforming to a second communication protocol, ii) a non-legacy long training field, and iii) a legacy signal conforming to a second communication protocol. field, and the second part of the preamble does not include any training fields. In this embodiment, a first plurality of constellation symbols are generated for a legacy short training field using a legacy tone plan conforming to a second communication protocol, and a second plurality of constellation symbols are generated using a non-legacy tone plan using a non-legacy tone plan. generated for a non-legacy long training field; and OFDM symbols for the data field include a third plurality of constellation symbols generated using a non-legacy tone plan.

In one embodiment, OFDM symbols are generated for a first portion of the preamble as a legacy preamble using a normal guard interval conforming to a second communication protocol, and OFDM symbols are generated for a second portion of the preamble using a long guard interval do. In a further embodiment, OFDM symbols for the non-legacy signal field and the non-legacy short training field of the second part of the preamble are generated using a normal guard interval, and OFDM symbols in the second part of the preamble are separated by a long guard interval is generated for the non-legacy long training field using In another embodiment, OFDM symbols are generated for a legacy signal field of a first portion of the preamble using a normal guard interval, and OFDM symbols are generated for a non-legacy signal field of a second portion of the preamble using a long guard interval is created In one embodiment, the second portion of the preamble is decodable by receiver devices conforming to the first communication protocol and the long guard interval of the second preamble indicates that the PHY data unit conforms to the range extension mode for the receiver conforming to the first communication protocol. signals to devices. In yet other embodiments, OFDM symbols are generated for a second portion of the preamble for a copy of the first OFDM symbol for i) a non-legacy signal field and ii) a non-legacy signal field using a long guard interval do. In one embodiment, the OFDM symbols include i) a double guard interval, ii) a first OFDM symbol for a field, and iii) a second OFDM symbol for a field that is a copy of the first OFDM symbol. It is generated for each field among the plurality of fields.

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 comprises a double guard interval according to a second communication protocol, followed by a first portion of the signal field and a second portion of the signal field, without a guard interval between the first signal field and the second signal field created to do

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

In another embodiment, the OFDM symbols for the data field are generated using a first tone interval and a long guard interval, and the OFDM symbols for the first portion of the preamble include i) a second tone interval different from the first tone interval, and ii) Generated using regular guard intervals. In a further embodiment, the second tone spacing of the first portion of the preamble is i) a legacy tone spacing conforming to the second communication protocol, and ii) an integer multiple of the first tone spacing of the data field; and the regular guard interval is a legacy guard interval conforming to the second communication protocol. In another embodiment, the OFDM symbols for the second preamble portion include i) at least a first OFDM symbol using a legacy tone spacing and a legacy guard spacing and ii) at least a second OFDM symbol using a first tone spacing and a long guard spacing is created by In still other embodiments, the OFDM symbols for the data field include a first tone comprising a plurality of constellation symbols in a first bandwidth portion of the channel bandwidth and a copy of the plurality of constellation symbols in a second bandwidth portion of the channel bandwidth. It is generated using the interval, and has the same bandwidth as the first bandwidth portion and the second bandwidth portion. In a further embodiment, generating OFDM symbols for the data field comprises generating copies of the plurality of constellation symbols comprising a predetermined phase shift.

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

In another embodiment, generating the OFDM symbols in the data field of the PHY data unit according to the range extension mode comprises: a non-legacy tone interval that does not conform to the second communication protocol and a non-legacy tone plan for the data field. generating OFDM symbols; and generating OFDM symbols for the first portion of the preamble using a second tone spacing different from the non-legacy tone spacing and a legacy tone plan different from the non-legacy tone plan. . In a further embodiment, the non-legacy tone plan includes at least one guard tone instead of a corresponding data tone of the legacy tone plan that is close to a direct current tone. In one embodiment, the non-legacy tone plan includes at least one data tone instead of a 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 contains fewer data tones than the legacy tone plan, and generating OFDM symbols for the data field using the non-legacy tone interval and the non-legacy tone plan comprises a non- and encoding the information bits for the OFDM symbols using an error correction code based on many data tones of the 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.

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

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

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

In some embodiments, the first plurality of information bits comprises a first set of one or more information bits indicative of a duration of a PHY data unit, by a receiver device conforming to a second communication protocol but not conforming to the first communication protocol. The preamble is formatted to be decodable, and the duration of the PHY data unit is determined based on the preamble. 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 corresponding i-th value of the second long training sequence, where i is the index.

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

In some embodiments, generating the first plurality of OFDM symbols comprises a first field generated by the receiver according to the first communication protocol to enable automatic detection of the first mode or the second mode by the receiver device generating a first plurality of OFDM symbols such that an auto-correlation output for ΓΠ signals i) a first mode of a first communication protocol or ii) a second mode of the first communication protocol do. 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, method 2800 includes: encoding a second plurality of information bits for a data field of a PHY data unit to generate a second plurality of encoded bits; mapping a second plurality of encoded bits to a second plurality of constellation symbols; generating a second plurality of modified constellation symbols, comprising multiplying the second plurality of constellation symbols by the predetermined sequence; generating a third plurality of orthogonal frequency division multiplexing (OFDM) symbols including the second plurality of modified constellation symbols; and generating the data field comprising the third plurality of OFDM symbols, wherein generating the PHY data unit comprises generating the PHY data unit including at least the preamble and the data field. includes steps.

29 is a diagram of an example PHY preamble portion 2900 that conforms to the HEW communication protocol, according to one embodiment, as compared to a preamble portion 2904 that conforms to the legacy protocol. In one embodiment, the network interface device 16 of the AP 14 is a data unit including a PHY preamble 2900 to the client station 25-1 via orthogonal frequency domain multiplexing (OFDM) modulation according to an embodiment. is configured to generate and transmit In one embodiment, the network interface device 27 of the client station 25 - 1 is configured to determine whether the data unit including the preamble 2900 conforms to the first communication protocol using techniques discussed below. do.

In one embodiment, the network interface device 27 of the client station 25 - 1 is also configured to generate and transmit a data unit including the PHY preamble 2900 to the AP 14 . In one embodiment, the network interface device 16 of the AP 14 is configured to determine whether the data unit including the preamble 2900 conforms to the first communication protocol using 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. Data units that include a similar preamble in preamble 2900 and conform to the first communication protocol may use other suitable bandwidths, such as, for example, 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz, or in other embodiments, other suitable bandwidths. can occupy The preamble 2900 addresses “mixed mode” situations, i.e., a client station in which the WLAN 10 conforms to a legacy communication protocol but not the first communication protocol (eg, a legacy client station 25-4). suitable for inclusion. The preamble 2900, in some embodiments, is also used in other situations.

Preamble portion 2900 includes L-LTF (204/304/504). In one embodiment, the 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 . The preamble portion 2900 further includes an L-SIG 206/306/506 including a guard interval 2920 and an L-SIG OFDM symbol 2924 according to an embodiment. The L-LTF (204/304/504) and the L-SIG (206/306/506) are the first part (eg, IEEE 802.11a standard, IEEE 802.11) of the corresponding legacy preamble 2904 according to an embodiment. g standard, the IEEE 802.11n standard, and/or a preamble conforming to the IEEE 802.11ac standard) is part of the first portion of the preamble 2900 . The legacy device may decode the L-SIG (206/306/506) and determine the length of the PHY data unit including the PHY preamble (2900). For example, the L-SIG 206/306/506 includes a length field set for a value indicating the length of the PHY data unit including the PHY preamble 2900 in one embodiment.

The preamble 2900 includes a second L-Sig field 2928 . In one embodiment, the L-Sig field 2928 is a copy of the L-Sig field 206/306/506. In one embodiment, the communication device configured to operate according to the first communication protocol detects a repetition of the L-Sig field 206/306/506 in the preamble 2900, and the L-Sig field 206/306/506 and determine whether the corresponding preamble 2900 conforms to the first communication protocol based on the sensed reception of . In one embodiment, upon repeated sensing of the L-Sig fields 206/306/506, 2928, the receiving device in one embodiment repeats the L-Sig as additional training information to improve channel estimation. Use a copy in the Sig fields. In some embodiments, the receiving device first decodes the L-SIG 206/306/506 and then uses the value of the length subfield in the L-SIG 206/306/506 to enter the L-Sig fields. Detect repetition of (206/306/506,2928). In another embodiment, the receiving device first senses the repetition of the L-Sig fields 206/306/506,2928, and then improves the decoding reliability of the L-Sig fields 206/306/506,2928 Combine the sensed multiple L-Sig fields 206/306/506,2928 to create and/or overlap within multiple L-Sig fields 206/306/506,2928 to improve channel estimation use the information.

In one embodiment, the preamble 2900 further includes a HEW-SIG1 field 2932 including a DGI 2936 and a HEW-SIG1 field OFDM symbol 2940 . The preamble 2900 also includes a second HEW-SIG1 field 2944 . In one embodiment, the HEW-SIG1 field 2944 is a copy of the HEW-SIG1 field 2932 . In one embodiment, the receiving device conforming to the first communication protocol uses, in one embodiment, a copy repeating HEW-SIG1 fields 2932 , 2944 as additional training information to improve the channel estimation. In another embodiment, the receiving device conforming to the first communication protocol uses the sensed multiple HEW-SIG1 fields 2932 , 2944 to improve decoding reliability of the HEW-SIG1 fields 2932 , 2944 . Redundant information in multiple HEW-SIG1 fields 2932 , 2944 is used to combine and/or improve channel estimation.

In one embodiment, the preamble 2900 is formatted such that a receiving device configured according to the first communication protocol determines whether a data unit including the preamble 2900 conforms to the first communication protocol. 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 corresponds to the modified legacy signal field 2306 of FIG. 23 . In this embodiment, the receiving device receiving the data unit including the preamble 2900 uses the LTF 204/304 long training sequence of the legacy communication protocol as described above with respect to FIG. 23 in one embodiment. /504) by performing a second cross-correlation of the LTF field 204/304/504 using the modified long training sequence of the first communication protocol and the first cross-correlation of the first communication protocol. It can detect whether the first communication protocol is followed.

In one embodiment, the preamble portion 3201 of the data unit 3200 is further formatted such that the legacy communication device determines whether the data unit 3200 does not conform to the legacy communication protocol. For example, in one embodiment, a first L-Sig field 3202, a second L-Sig field ( 3204) and HEW-SIG1 field 3208 are each modulated. For example, upon detecting BPSK modulation in 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 in one embodiment will stop processing the data unit 3200 and refrain from accessing the medium for a duration determined based on the L-Sig field 3204 .

30 is a diagram of a portion 3000 of an example PHY preamble conforming to a first communication protocol according to another embodiment as compared to a portion 2904 of the preamble conforming to the legacy protocol. The preamble 3000 is similar to the preamble 2900 of FIG. 29 and like-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 and transmit a data unit including the PHY preamble 3000 to the client station 25-1 via OFDM modulation according to an embodiment. do. In one embodiment, the network interface device 27 of the client station 25 - 1 is configured to determine whether the data unit including the preamble 3000 conforms to the first communication protocol using techniques discussed below. do.

In one embodiment, the network interface device 27 of the client station 25 - 1 is also configured to generate and transmit 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 whether the data unit including the preamble 3000 conforms to the first communication protocol using techniques discussed below.

According to one embodiment, the data unit including the PHY preamble 3000 conforms to the first communication protocol and occupies a 20 MHz bandwidth. Data units comprising a similar preamble in preamble 3000 and conforming to the first communication protocol may use other suitable bandwidths, such as, for example, 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz, or in other embodiments, other suitable bandwidths. can occupy The preamble 3000 addresses “mixed mode” situations, i.e., a client station in which the WLAN 10 conforms to the legacy communication protocol but not the first communication protocol (eg, the legacy client station 25-4). suitable for inclusion. The preamble 3000 is, in some embodiments, also used in other situations.

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

The L-LTF (204/304/504) and the L-SIG (206/306/506) are the first part (eg, IEEE 802.11a standard, IEEE 802.11) of the corresponding legacy preamble 2904 according to an embodiment. g standard, the IEEE 802.11n standard, and/or a preamble conforming to the IEEE 802.11ac standard) is part of the first portion of the preamble 3000 . The legacy device may decode the L-SIG (206/306/506) and determine the length of the PHY data unit including the PHY preamble (3000). For example, the L-SIG 206/306/506 includes a set of length fields for a value indicating the length of the PHY data unit including the PHY preamble 3000 in one embodiment.

In one embodiment, a communication device configured to operate according to the HEW protocol detects repetition of HEW-SIG1 fields 3004, 3016 in preamble 3000, and responds to the detected repetition of HEW-SIG1 field 3004, 3016. based on the preamble 3000 is configured to determine whether or not the HEW communication protocol is compliant.

In one embodiment, a receiving device conforming to the HEW protocol uses a copy of repeating HEW-SIG1 fields 3004 , 3016 as additional training information to improve channel estimation, in one embodiment. In another embodiment, the receiving device conforming to the HEW protocol combines the sensed multiple (3004, 3016) to improve decoding reliability of the HEW-SIG1 fields (3004, 3016) and/or to improve channel estimation Redundancy information in multiple HEW-SIG1 fields 3004 and 3016 is used.

31 is a diagram of a portion 3100 of an example PHY preamble conforming to a first communication protocol according to another embodiment as compared to a portion 2904 of a preamble conforming to a legacy protocol. Preamble 3100 is similar to preamble 2900 of FIG. 29 and preamble 3000 of FIG. 30 and equally-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 and transmit a data unit including the PHY preamble 3100 to the client station 25-1 via OFDM modulation according to an embodiment. do. In one embodiment, the network interface device 27 of the client station 25 - 1 is configured to determine whether the data unit including the preamble 3100 conforms to the first communication protocol using techniques discussed below. do.

In one embodiment, the network interface device 27 of the client station 25 - 1 is also configured to generate and transmit a data unit including the PHY preamble 3100 to the AP 14 . In one embodiment, the network interface device 16 of the AP 14 is configured to determine whether the data unit including the preamble 3100 conforms to the first communication protocol using techniques discussed below.

According to one embodiment, the data unit including the PHY preamble 3100 conforms to the first communication protocol and occupies a 20 MHz bandwidth. Data units comprising a similar preamble in preamble 3100 and conforming to the first communication protocol may use other suitable bandwidths, such as, for example, 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz, or in other embodiments, other suitable bandwidths. can occupy The preamble 3100 addresses “mixed mode” situations, i.e., a client station in which the WLAN 10 conforms to a legacy communication protocol but does not conform to the first communication protocol (eg, a legacy client station 25-4). suitable for inclusion. The preamble 3100, in some embodiments, is also used in other situations.

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

Unlike the preamble 3000 , the preamble 3100 includes a second L-Sig field 2928 . In one embodiment, the L-Sig field 2928 is a copy of the L-Sig field 206/306/506.

The L-LTF (204/304/504) and the L-SIG (206/306/506) are the first part (eg, IEEE 802.11a standard, IEEE 802.11) of the corresponding legacy preamble 2904 according to an embodiment. g standard, the IEEE 802.11n standard, and/or a preamble conforming to the IEEE 802.11ac standard) is part of the first portion of the preamble 3000 . The legacy device may decode the L-SIG (206/306/506) and determine the length of the PHY data unit including the PHY preamble (3000). For example, the L-SIG 206/306/506 includes a set of length fields for a value indicating the length of the PHY data unit including the PHY preamble 3000 in one embodiment.

In one embodiment, a communication device configured to operate according to the HEW protocol detects repetition of the L-Sig field 206/306/506 in the preamble 2900, and detects the detection of the L-Sig field 206/306/506. based on the repeated iteration, determine whether the corresponding preamble 2900 conforms to the HEW protocol. In one embodiment, upon repeated sensing of the L-Sig fields 206/306/506, 2928, the receiving device in one embodiment repeats the L-Sig as additional training information to improve channel estimation. Use a copy in the Sig fields. In some embodiments, the receiving device first decodes the L-SIG 206/306/506 and then uses the value of the length subfield in the L-SIG 206/306/506 to enter the L-Sig fields. Detect repetition of (206/306/506,2928). In another embodiment, the receiving device first senses the repetition of the L-Sig fields 206/306/506,2928, and then improves the decoding reliability of the L-Sig fields 206/306/506,2928 Combine the sensed multiple L-Sig fields 206/306/506,2928 to create and/or overlap within multiple L-Sig fields 206/306/506,2928 to improve channel estimation use the information.

In one embodiment, a communication device configured to operate according to the HEW protocol detects repetition of HEW-SIG1 fields 3004, 3016 in preamble 3000, and responds to the detected repetition of HEW-SIG1 field 3004, 3016. based on the preamble 3000 is configured to determine whether or not the HEW communication protocol is compliant.

In one embodiment, a receiving device conforming to the HEW protocol uses a copy of repeating HEW-SIG1 fields 3004 , 3016 as additional training information to improve channel estimation, in one embodiment. In another embodiment, the receiving device conforming to the HEW protocol combines the sensed multiple (3004, 3016) to improve decoding reliability of the HEW-SIG1 fields (3004, 3016) and/or to improve channel estimation Redundancy information in multiple HEW-SIG1 fields 3004 and 3016 is used.

32 is a diagram of a preamble 3200 portion of an OFDM data unit that the network interface device 16 of the AP 14 is configured to generate via OFDM modulation and transmit to the client station 25-1 via OFDM modulation according to an embodiment. In one embodiment, the network interface device 27 of the client station 25 - 1 is configured to determine whether the data unit including the preamble 3200 conforms to the first communication protocol using techniques discussed below. do.

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 3200 to the AP 14 . In one embodiment, the network interface device 16 of the AP 14 is configured to determine whether the data unit including the preamble 3200 conforms to the first communication protocol using techniques discussed below.

The data unit including the preamble 3200 conforms to the first communication protocol and occupies a 20 MHz bandwidth. Data units conforming to the first communication protocol having similar preambles in preamble 3200 may occupy other suitable bandwidths, such as, for example, 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz, or in other embodiments, other suitable bandwidths. there is. The data unit containing the preamble 3200 may be used in “mixed mode” situations, i.e., a client station in which the WLAN 10 conforms to a legacy communication protocol but not the first communication protocol (eg, a legacy client station 25 It is suitable when including -4)). The preamble 3200, in some embodiments, is also used in other situations.

The preamble 3200 includes a first long guard interval 3202, a long training field 3204 having a first portion 3204-1 and a second portion 3204-2, a second long guard interval 3206, a second 1 L-Sig field 3206-1, 2nd L-Sig field 3206-2, 3rd long guard interval 3202, 1st HEW signal field HEW-SIG1 3208, 4th long guard interval ( 3202 ) and a preamble portion 3210 having a second HEW signal field HEW-SIG2 3210 . In one embodiment, the first L-Sig field 3602-1 corresponds to the L-Sig field 706 of the data unit 700, and the second L-Sig field 3602-2 is the first L- A copy of the Sig field (3602-1). In one embodiment, each long guard interval 3202 is a double guard interval that is twice as long as the regular guard interval defined by the legacy communication protocol. For example, in one embodiment, the regular guard interval defined by the legacy communication protocol is 0.8 μs, whereas the double guard interval is 1.6 μs. In another embodiment, each of the long guard intervals 3202 has another suitable value greater than the regular guard interval defined by the legacy communication protocol. For example, the regular guard interval defined by the legacy communication protocol is 0.8 μs, but in various embodiments the long guard interval is 1.2 μs, 2.4 μs, 3.2 μs, or any other suitable value greater than 0.8 μs.

With continued reference to FIG. 32 , a legacy data unit format 3220 is illustrated for reference. A data unit conforming to the format 3220 includes a double guard interval 3222, a long training field 3224 having a first part 3224-1 and a second part 3224-2, a first regular guard interval 3225 , L-Sig field 3226, OFDM symbol 3228 corresponding to a signal field (eg, HT-SIG1 field or VHT-SIG1 field), or data unit 3200 depending on the specific legacy protocol to which it corresponds. OFDM symbol of the data part, third regular guard interval 3225, and OFDM symbol 3230 corresponding to the signal field (eg, HT-SIG2 field or VHT-SIG2 field), or format 3200 Contains OFDM symbols in the data portion that depend on the specific legacy protocol.

In one embodiment, the preamble portion 3201 of the data unit 3200 is formatted such that the receiving device conforming to the first communication protocol determines whether the data unit 3200 corresponds to the first communication protocol. 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 is the modified legacy signal of FIG. 23 . Corresponds to field 2306. In this embodiment, the receiving device receiving the data unit 3200 uses the long training sequence of the legacy communication protocol as described above with respect to FIG. 23 in one embodiment to set the first of the long training field 3202 Perform a second cross-correlation of the L_LTF field 3202 using the cross-correlation and the modified long training sequence of the first communication protocol to detect whether the data unit 3200 conforms to the first communication protocol. can Additionally or alternatively, in one embodiment, the receiving device receiving the data unit 3200 detects the presence of the second L-Sig field 3205 in the preamble portion 3201 so that the data unit 3200 is sent to the first It can detect conformance to the communication protocol.

In one embodiment, the preamble portion 3201 of the preamble 3200 is further formatted such that the legacy communication device determines whether the data unit including the preamble 3200 does not conform to the legacy communication protocol. For example, in one embodiment, a first L-Sig field 3202, a second L-Sig field ( 3204) and HEW-SIG1 field 3208 are each modulated. For example, upon detecting BPSK modulation in 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 in one embodiment will stop processing the data unit 3200 and refrain from accessing the medium for a duration determined based on the L-Sig field 3204 . As illustrated in FIG. 32 , in one embodiment the first L-Sig field 3204 in the time domain is the corresponding OFDM symbol in the legacy preamble 3220 because of the long guard interval preceding the L-Sig field 3210 . It is not aligned to L-SIG (3224). On the other hand, the second L-Sig field 3212 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 constellation points of the first L-Sig field 3206-1 and The constellation points of the HEW-SIG1 field 3208 are pre-rotated. In one embodiment, the constellation points of the first L-Sig field 3206-1 and of the HEW-SIG1 field 3208 are rotated by an amount determined by the length of the long guard interval by the duration of the long guard interval. . For example, in one embodiment where the long guard interval is doubled because the regular guard interval is defined by the legacy communication protocol, in each of the first L-Sig field 3206-1 and in the HEW-SIG1 field 3208 The constellation points are rotated by 90 degrees as described above with respect to Figures 14b-14c. Consequently, in this embodiment the first L-Sig field 3206-1 and the HEW-SIG1 field 3208 are each modulated using reversed QBPSK (R-QBPSK) modulation.

In one embodiment, the second L-Sig field 3206-2 is aligned with the corresponding OFDM symbol 3228 in the legacy format 3220 and thus, the second L-Sig field 3206-2 uses BPSK modulation. is modulated using 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.

33 is a diagram of a preamble portion 3300 of an OFDM data unit that the network interface device 16 of the AP 14 is configured to generate via OFDM modulation and transmit to the client station 25 - 1 according to an embodiment. In one embodiment, the network interface device 27 of the client station 25 - 1 is configured to determine whether the data unit including the preamble 3300 conforms to the first communication protocol using techniques discussed below. do.

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

The data unit including the preamble 3300 conforms to the first communication protocol and occupies a 20 MHz bandwidth. Data units having similar preambles in preamble 3300 and conforming to the first communication protocol may occupy other suitable bandwidths, such as, for example, 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz, or in other embodiments, other suitable bandwidths. there is.

In the preamble portion 3301 of the preamble 3300, a second long guard interval 3202-2 is replaced with a regular guard interval 3302, and a second L-Sig field 3206-2 is a data unit 3300 The preamble 3300 is similar to the preamble 3200 of FIG. 2 except that it is omitted from . Additionally, the preamble portion 3301 includes a first HEW-SIG1 field 3208-1 and a second HEW-SIG1 field 3208-2 compared to a single HEW-SIG1 field 3208 of the preamble 3200 . In one embodiment, the second HEW-SIG1 field 3208-2 is a copy of the first HEW-SIG1 field 3208-1.

In one embodiment, the L-Sig field 3206 and the second HEW-SIG1 field 3208 - 2 are each aligned with its corresponding OFDM symbol in the legacy format 3220 . On the other hand, the first HEW-SIG1 field 3208 - 1 is not aligned with its corresponding OFDM symbol of the legacy format 3220 . In one embodiment, the constellation points of the first HEW-Sig field 3208-1 are pre-rotated (eg, such that the receiving device detects BPSK modulation within a shifted FFT window corresponding to OFDM symbol 3228 ). by 90 degrees). In one embodiment, the second HEW-SIG1 field 3208 - 2 is modulated using BPSK modulation so that the receiving device can detect the BPSK modulation of the corresponding OFDM symbol 3330 in the legacy format 3200 . However, in this case, in one embodiment, the modulation of the second HEW-SIG1 field 3208-2 (BPSK) is the same as the modulation of the first HEW-SIG1 field 3208-1 (eg, R-QBPSK). different. As a result, the cyclic prefix of the second HEW-SIG 1 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 with the same modulation scheme as the first HEW-SIG1 field 3208-1 (eg, R-QBPSK). In this 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 non-legacy device uses the preamble 3300 ) allows more accurately detecting whether the data unit including the data unit 3300 corresponds to the first communication protocol based on detecting repetition of the HEW-SIG1 field in the data unit 3300 . Moreover, in this embodiment, the legacy device will detect shifted modulation (e.g., quadrature phase shift modulation) within the corresponding OFDM symbol 3230, which is converted into data units according to the IEEE-802-11ac standard ( 3200) can lead to five senses. However, the legacy device will interpret the second HEW-SIG1 field 3208-2 as a VHT-SIG2 field, and will fail the CRC check of the VHT-SIG2 field. In one embodiment, according to the IEEE 802.11ac standard, the legacy device will then discard the data unit with the preamble 3300 and, in one embodiment, suppress the constraint medium access indicated in the L-Sig field 3206 . . Various methods for ensuring that a legacy device detects a CRC error based on the second HEW-SIG1 field 3208-2 decoding are described in U.S. Pat. Patent application No. 13/856,277, (Attorney Docket No. MP4709), which is incorporated herein by reference in its entirety.

34 is a diagram of a preamble portion 3400 of an OFDM data unit that the network interface device 16 of the AP 14 is configured to generate via OFDM modulation and transmit to the client station 25-1, according to an embodiment. In one embodiment, the network interface device 27 of the client station 25 - 1 is configured to determine whether the data unit including the preamble 3400 conforms to the first communication protocol using techniques discussed below. do.

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

The data unit including the preamble 3400 conforms to the first communication protocol and occupies a 20 MHz bandwidth. Data units having similar preambles in preamble 3400 and conforming to the first communication protocol may occupy other suitable bandwidths, such as, for example, 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz, or in other embodiments, other suitable bandwidths. there is.

The preamble 3400 is, in one embodiment, that the preamble portion 3401 of the preamble 3400 includes long guard intervals between OFDM symbols of the preamble portion 3401, and does not include overlapping of the L-Sig field 3206. It is similar to the preamble 3200 of FIG. 32 except that it is not Additionally, unlike preamble 3200 , in the illustrated embodiment the pre-rotation of constellation points within OFDM symbols of preamble 3400 is not aligned to corresponding OFDM symbols in legacy format 3220 . does not

35 shows a preamble portion 3500 of an OFDM data unit configured to be transmitted by a network interface device 16 of an AP 14 to a client station 25-1 via orthogonal frequency domain multiplexing (OFDM) modulation, according to an embodiment. ) is a diagram of In one embodiment, the network interface device 27 of the client station 25 - 1 is configured to determine whether the data unit including the preamble 3500 conforms to the first communication protocol using techniques discussed below. do.

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

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

36 is a diagram of an example PHY preamble portion 3600 that conforms to a first communication protocol, according to another embodiment, as compared to a portion 2904 of a preamble that conforms to the legacy protocol. The preamble 3600 is similar to the preamble 2900 of FIG. 29 and like-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 and transmit a data unit including the PHY preamble 3600 to the client station 25-1 via OFDM modulation according to an embodiment. do. In one embodiment, the network interface device 27 of the client station 25 - 1 is configured to determine whether the data unit including the preamble 3600 conforms to the first communication protocol using techniques discussed below. do.

In one embodiment, the network interface device 27 of the client station 25 - 1 is also configured to generate and transmit a data unit including the PHY preamble 3600 to the AP 14 . In one embodiment, the network interface device 16 of the AP 14 is configured to determine whether the data unit including the preamble 3600 conforms to the first communication protocol using 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. Data units comprising a similar preamble in preamble 3600 and conforming to the first communication protocol may use other suitable bandwidths, such as, for example, 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz, or in other embodiments, other suitable bandwidths. can occupy The preamble 3600 addresses “mixed mode” situations, i.e., a client station in which the WLAN 10 conforms to a legacy communication protocol but not the first communication protocol (eg, a legacy client station 25-4). suitable for inclusion. The preamble 3600, in some embodiments, is also used in other situations.

In one embodiment, the HEW-Sig field 3604 in the time domain is the corresponding OFDM symbol (V)HT-SIG1 in the legacy preamble 2904 because of the long guard interval 2936 preceding the HEW-SIG1 OFDM symbol 2940 . It is not aligned to field 3608 .

In one embodiment, the constellation points of the HEW-SIG1 OFDM symbol 2940 are rotated by the duration of the long guard interval 2936 by an amount determined by the length of the long guard interval 2936 . For example, in one embodiment where the long guard interval is doubled because the regular guard interval is defined by the legacy communication protocol, the constellation points of the HEW-SIG1 OFDM symbol 2940 are described above with respect to Figures 14B-14C. rotated by 90 degrees as if Consequently, in one embodiment the HEW-SIG1 field 3604 is modulated using inverted QBPSK (R-QBPSK) modulation.

37 is a preamble portion of an OFDM data unit configured for network interface device 16 of AP 14 to generate via orthogonal frequency domain multiplexing (OFDM) modulation and transmit to client station 25-1, according to an embodiment. (3700) is a diagram. In one embodiment, the network interface device 27 of the client station 25-1 is configured to determine whether the data unit including the preamble 3700 conforms to the first communication protocol using techniques discussed below. do.

In one embodiment, the network interface device 27 of the client station 25 - 1 is also configured to generate and transmit a data unit including the preamble 3700 to the AP 14 . In one embodiment, the network interface device 16 of the AP 14 is configured to determine whether the data unit including the preamble 3700 conforms to the first communication protocol using techniques discussed below.

The data unit including the preamble 3700 conforms to the first communication protocol and occupies a 20 MHz bandwidth. Data units comprising similar preambles in preamble 3700 and conforming to the first communication protocol may occupy other suitable bandwidths, such as, for example, 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz, or in other embodiments, other suitable bandwidths. can

The preamble 3700 is the preamble 3300 of FIG. 33 except that the preamble 3700 omits the second (replica) HEW-SIG1 field 3208-2 and includes an auto-sensing OFDM symbol 3706. similar to In one embodiment, the receiving device may detect whether the data unit including the preamble 3700 conforms to the first communication protocol based on detecting the auto-sensing OFDM symbol 3706 in the data unit 3700 . there is. In the illustrated embodiment the auto-sensing symbol 3706 is immediately after the L-Sig field 3206 . The auto-sensing symbol 3706 is aligned with its corresponding OFDM symbol in the legacy data unit format 3220, and in one embodiment for at least non-zero tones of the tones of the corresponding OFDM symbol in the legacy format 3220. It is modulated using BPSK modulation. In one embodiment, the long guard interval 3710 is used as the HEW-SIG1 field 3208 of the preamble 3700 . In one embodiment, the HEW-SIG1 field 3208 of the preamble 3700 is not aligned with the corresponding OFDM symbol of the legacy format 3220 . In one embodiment, the constellation points of the HEW-SIG1 field 3208 are pre-rotated (e.g., pre-rotated) such that the legacy receiving device detects the BPSK modulation using the FFT window of the corresponding OFDM symbol in the legacy format 3220. by 90 degrees).

38A-38D are diagrams illustrating auto-sensing OFDM symbol 3706 of data unit 3700 in accordance with some representative embodiments. Turning first to FIG. 38A , in one embodiment, the auto-sensing OFDM symbol 3706 includes five repetitions of an L-LTF sequence defined by 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 by reusing the data. The unit 3700 may detect whether the first communication protocol is compliant. Turning now to FIG. 38B , in one embodiment, the auto-sensing OFDM symbol 3706 is two of an appropriate predetermined sequence that is longer (corresponding to more OFDM tones) compared to the L-STF sequence defined by the legacy communication protocol. contains repetitions of For example, the predetermined sequence may in one embodiment, within each 20 MHz band of the data unit 3700, include a different OFDM tone (eg, a set [+/- 2, +/4, +/- 6) each time. , etc.] OFDM tones with indices in ). Turning now to 38c and in one embodiment, the auto-sensing OFDM symbol 3706 includes five repetitions of the last portion (eg, 0.8 μs duration) of the L-Sig field 3206 . Turning now to FIG. 38C , in one embodiment, the auto-sensing OFDM symbol 3706 consists of two repetitions of a large portion (eg, 1.6 μs) of the L-Sig field 3206, followed by the L-Sig field ( 3206), including a postfix portion comprising a sub-portion of a large portion (eg, 0.8 μs).

In other embodiments, the auto-sensing OFDM symbol 3706 is any other suitable preamble that can be used at the receiving device to auto-sense whether the data unit including the preamble 3700 conforms to the first communication protocol. contains the determined sequence. For example, the auto-sensing OFDM symbol 3706 comprises a predetermined Barker code sequence, a predetermined Golay code sequence, or any other suitable predetermined sequence in various embodiments. . In one embodiment, the receiving device senses whether the data unit including the preamble 3700 conforms to the first communication protocol by detecting the high correlation of the auto-sensing OFDM symbols 3706 in a predetermined sequence.

39 is a diagram of a portion 3900 of an example PHY preamble conforming to a first communication protocol according to another embodiment as compared to a portion 2904 of a preamble conforming to a legacy protocol. The preamble 3900 is similar to the preamble 2900 of FIG. 29 and the same-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 and transmit a data unit including the PHY preamble 3900 to the client station 25-1 via OFDM modulation according to an embodiment. do. In one embodiment, the network interface device 27 of the client station 25 - 1 is configured to determine whether the data unit including the preamble 3900 conforms to the first communication protocol using techniques discussed below. do.

In one embodiment, the network interface device 27 of the client station 25 - 1 is also configured to generate and transmit a data unit including the PHY preamble 3900 to the AP 14 . In one embodiment, the network interface device 16 of the AP 14 is configured to determine whether the data unit including the preamble 3900 conforms to the first communication protocol using 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. Data units comprising a similar preamble in preamble 3900 and conforming to the first communication protocol may use other suitable bandwidths, such as, for example, 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz, or in other embodiments, other suitable bandwidths. can occupy The preamble 3900 addresses “mixed mode” situations, i.e., a client station in which the WLAN 10 conforms to a legacy communication protocol but does not conform to the first communication protocol (eg, a legacy client station 25-4). suitable for inclusion. The preamble 3900, in some embodiments, is also used in other situations.

L-SIG (206/36/506), L-SIG (2928), and HEW-SIG1 (2932) are modulated using BPSK, whereas HEW-SIG1 (2944) according to an embodiment is rotated BPSK ( For example, it is modulated using Q-BPSK).

40A is a diagram of a portion 4000 of another example PHY preamble conforming 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 and transmit a data unit comprising the PHY preamble 4000 to the client station 25-1 via OFDM modulation according to an embodiment. do. In one embodiment, the network interface device 27 of the client station 25 - 1 is configured to determine whether the data unit including the preamble 4000 conforms to the first communication protocol using techniques discussed below. do.

In one embodiment, the network interface device 27 of the client station 25 - 1 is also configured to generate and transmit a data unit including the PHY preamble 4000 to the AP 14 . In one embodiment, the network interface device 16 of the AP 14 is configured to determine whether the data unit including the preamble 4000 conforms to the first communication protocol using techniques discussed below.

According to one embodiment, the data unit including the PHY preamble 4000 conforms to the first communication protocol and occupies a 20 MHz bandwidth. Data units comprising a similar preamble in preamble 4000 and conforming to the first communication protocol may use other suitable bandwidths, such as, for example, 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz, or in other embodiments, other suitable bandwidths. can occupy The preamble 4000 addresses “mixed mode” situations, i.e., a client station in which the WLAN 10 conforms to the legacy communication protocol but not the first communication protocol (eg, the legacy client station 25-4). suitable for inclusion. The preamble 4000 is also used in other situations, in some embodiments.

The 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 . According to an embodiment, the legacy device may decode the L-SIG 4016 and determine the length of the PHY data unit including the PHY preamble 4000 . For example, the L-SIG 4016 includes a set of length fields for a value indicating the length of the PHY data unit including the PHY preamble 4000 in one embodiment.

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. 23 . do. In this embodiment, the receiving device conforming to the first communication protocol uses the long training sequence of the legacy communication protocol as described above with respect to FIG. 23 in one embodiment to first cross- Whether the data unit including the preamble 4000 conforms to the first communication protocol is determined by performing a second cross-correlation of the L_LTF field 4012 using the correlation and the modified long training sequence of the first communication protocol. can detect

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

40B is a diagram of a portion 4050 of another example PHY preamble conforming to a first communication protocol according to another embodiment. Preamble portion 4050 is similar to preamble portion 4000 and like-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 and transmit a data unit including the PHY preamble 4050 to the client station 25-1 via OFDM modulation according to an embodiment. do. In one embodiment, the network interface device 27 of the client station 25 - 1 is configured to determine whether the data unit including the preamble 4050 conforms to the first communication protocol using techniques discussed below. do.

In one embodiment, the network interface device 27 of the client station 25 - 1 is also configured to generate and transmit a data unit including the PHY preamble 4050 to the AP 14 . In one embodiment, the network interface device 16 of the AP 14 is configured to determine whether the data unit including the preamble 4050 conforms to the first communication protocol using techniques discussed below.

According to one embodiment, the data unit including the PHY preamble 4050 conforms to the first communication protocol and occupies a 20 MHz bandwidth. Data units comprising a similar preamble in preamble 4050 and conforming to the first communication protocol may use other suitable bandwidths, such as, for example, 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz, or in other embodiments, other suitable bandwidths. can occupy The preamble 4050 addresses “mixed mode” situations, i.e., a client station in which the WLAN 10 conforms to a legacy communication protocol but not the first communication protocol (eg, a legacy client station 25-4). suitable for inclusion. The preamble 4050, in some embodiments, is also used in other situations.

According to an embodiment, the legacy device may decode the L-SIG 4016 and determine the length of the PHY data unit including the PHY preamble 4050 . For example, the L-SIG 4016 includes a set of length fields for a value indicating the length of the PHY data unit including the PHY preamble 4050 in one embodiment.

The preamble 4050 also includes one or more second L-SIGs 4054 . In one embodiment, the one or more second L-SIGs 4054 are replicas of the 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. 23 . do. In this embodiment, the receiving device conforming to the first communication protocol uses the long training sequence of the legacy communication protocol as described above with respect to FIG. 23 in one embodiment to first cross- Whether the data unit including the preamble 4050 conforms to the first communication protocol by performing a second cross-correlation of the L_LTF field 4012 using the correlation and the modified long training sequence of the first communication protocol. can detect

Additionally or alternatively, in one embodiment, the receiving device receiving the data unit including the preamble 4050 detects the presence of one or more second L-Sig fields 4054 in the preamble portion 4050 of the data unit It can detect conformance to this first communication protocol.

In one embodiment, DGI is included between L-SIG 4054b and HEW-STF 4020a. In one embodiment, the individual DGIs are between the HEW-STF OFDM symbol 4020b and the HEW-LTF1 OFDM symbol 4024, between the HEW-LTF1 OFDM symbol 4024 and the HEW-SIGA OFDM symbol 4028, HEW-SIGA between OFDM symbol 4028 and one or more HEW-LTFs OFDM symbols 4032 , and between one or more HEW-LTFs OFDM symbols 4032 and HEW-SIGB OFDM symbol 4036 .

In some embodiments, techniques such as those described above detect data units conforming to a first communication protocol and detect any one of a number of modes (defined by the first communication protocol) to which the data units correspond. can be used for For example, FIG. 41 is a diagram of a portion 4100 of an example PHY preamble conforming to a first communication protocol according to another embodiment as compared to a portion 2904 of a preamble conforming to a legacy protocol. Additionally, the PHY preamble 4100 also corresponds to a range extension mode of the first communication protocol. 41 also includes a diagram of a portion 4104 of an example PHY preamble conforming to a first communication protocol according to another embodiment as compared to a portion 2904 of a preamble conforming to the legacy protocol. Additionally, the PHY preamble 4104 also corresponds to the normal mode of the first communication protocol.

In one embodiment, the network interface device 16 of the AP 14 is a data unit including a PHY preamble 4100 or a PHY preamble 4104 to the client station 25-1 via OFDM modulation according to an embodiment. is configured to generate and transmit In one embodiment, the network interface device 27 of the client station 25 - 1 determines whether the data unit including the preamble 4100 or the preamble 4104 conforms to the first communication protocol using techniques discussed below. is configured to determine whether or not In one embodiment, the network interface device 27 of the client station 25-1 determines whether the data unit including the preamble 4100 conforms to the range extension mode and determines the preamble 4104 using techniques discussed below. and determine whether the containing data unit conforms to a regular mode.

In one embodiment, the network interface device 27 of the client station 25 - 1 is also configured to generate and transmit data units including the PHY preamble 4100 or the PHY preamble 4104 to the AP 14 . In one embodiment, the network interface device 16 of the AP 14 determines whether the data unit including the PHY preamble 4100 or the PHY preamble 4104 conforms to the first communication protocol using techniques discussed below. is configured to determine In one embodiment, the network interface device 16 of the AP 14 determines whether the data unit including the preamble 4100 conforms to the range extension mode and the data including the preamble 4104 using techniques discussed below. and determine whether the unit complies with the regular mode.

According to one embodiment, the data unit including the PHY preamble 4100 conforms to the first communication protocol and occupies a 20 MHz bandwidth. Data units comprising a similar preamble in preamble 4100 and conforming to the first communication protocol may use other suitable bandwidths, such as, for example, 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz, or in other embodiments, other suitable bandwidths. can occupy According to one embodiment, the data unit including the PHY preamble 4104 conforms to the first communication protocol and occupies a 20 MHz bandwidth. Data units comprising a similar preamble in preamble 4104 and conforming to the first communication protocol may use other suitable bandwidths, such as, for example, 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz, or in other embodiments, other suitable bandwidths. can occupy

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

In one embodiment, a communication device configured to operate according to the HEW protocol detects repetition of the L-Sig field 206/306/506 in the preamble 4100, and detects the detection of the L-Sig field 206/306/506. and determine whether the corresponding preamble 4100 conforms to the first communication protocol based on the repeated repetition. Additionally, the communication device configured to operate according to the first communication protocol determines whether the preamble 4100 complies with the range extension mode of the first communication protocol based on the sensed repetition of the L-Sig field 206/306/506. is configured to determine

The 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. 23 . do. In this embodiment, the receiving device conforming to the first communication protocol uses the long training sequence of the legacy communication protocol as described above with respect to FIG. 23 in one embodiment to conduct the first cross- of the L-LTF 4108 - Whether the data unit including the preamble 4104 conforms to the first communication protocol by performing a second cross-correlation of the L_LTF field 4112 using the correlation and the modified long training sequence of the first communication protocol. can detect In a similar manner, a receiving device conforming to the first communication protocol may sense whether the data unit including the preamble 4104 conforms to the regular 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. 23 . do. In this embodiment, the receiving device conforming to the HEW protocol uses the long training sequence of the legacy communication protocol as described above with respect to FIG. 23 in one embodiment to perform the first cross-correlation of the L-LTF 2912 . 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 whether the data unit including the preamble 4100 conforms to the HEW communication protocol. there is.

42 is a diagram of a portion 4200 of an example PHY preamble conforming to a first communication protocol according to another embodiment as compared to a portion 2904 of a preamble conforming to a legacy protocol. Additionally, the PHY preamble 4200 also corresponds to a range extension mode of the first communication protocol. 42 is a diagram of a portion 4204 of an example PHY preamble conforming to a first communication protocol according to another embodiment as compared to a portion 2904 of a preamble conforming to a legacy protocol. Additionally, the PHY preamble 4204 also corresponds to the regular mode of the first communication protocol.

In one embodiment, the network interface device 16 of the AP 14 is a data unit including a PHY preamble 4200 or a PHY preamble 4204 to the client station 25-1 via OFDM modulation according to an embodiment. is configured to generate and transmit In one embodiment, the network interface device 27 of the client station 25 - 1 determines whether the data unit including the preamble 4200 or the preamble 4204 conforms to the first communication protocol using techniques discussed below. is configured to determine whether or not In one embodiment, the network interface device 27 of the client station 25-1 determines whether the data unit including the preamble 4200 conforms to the range extension mode and determines the preamble 4204 using techniques discussed below. and determine whether the containing data unit conforms to the regular mode.

In one embodiment, the network interface device 27 of the client station 25 - 1 is also configured to generate and transmit data units including the PHY preamble 4200 or the PHY preamble 4204 to the AP 14 . In one embodiment, the network interface device 16 of the AP 14 uses techniques discussed below to determine whether the data unit including the PHY preamble 4200 or the PHY preamble 4204 conforms to the first communication protocol. is configured to determine In one embodiment, the network interface device 16 of the AP 14 determines whether the data unit including the preamble 4200 conforms to the range extension mode and the data including the preamble 4204 using techniques discussed below. and determine whether the unit complies with the regular mode.

According to one embodiment, the data unit including the PHY preamble 4200 conforms to the first communication protocol and occupies a 20 MHz bandwidth. Data units comprising a similar preamble in preamble 4200 and conforming to the first communication protocol may use other suitable bandwidths, such as, for example, 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz, or in other embodiments, other suitable bandwidths. can occupy According to one embodiment, the data unit including the PHY preamble 4204 conforms to the first communication protocol and occupies a 20 MHz bandwidth. Data units comprising a similar preamble in preamble 4204 and conforming to the first communication protocol may use other suitable bandwidths, such as, for example, 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz, or in other embodiments, other suitable bandwidths. can occupy

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

In one embodiment, a communication device configured to operate according to a first communication protocol detects repetition of HEW-SIG1 fields 3004, 3016 in preamble 4200, and detects a repetition of HEW-SIG1 field 3004, 3016 in preamble 4200. and determine, based on the iteration, whether the corresponding preamble 4200 conforms to the first communication protocol. Additionally, the communication device configured to operate according to the first communication protocol determines, based on the sensed repetition of the HEW-SIG1 fields 3004 , 3016 , whether the preamble 4200 complies with the range extension mode of the first communication protocol. configured to decide.

The preamble 4204 is similar to the preamble 4104 of FIG. 41 and the same-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. 23 . do. In this embodiment, the receiving device conforming to the first communication protocol uses the long training sequence of the legacy communication protocol as described above with respect to FIG. 23 in one embodiment to conduct the first cross- of the L-LTF 4108 - Whether the data unit including the preamble 4104 conforms to the first communication protocol by performing a second cross-correlation of the L_LTF field 4112 using the correlation and the modified long training sequence of the first communication protocol. can detect In a similar manner, a receiving device conforming to the first communication protocol may sense whether the data unit including the preamble 4104 conforms to the regular 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. 23 . do. In this embodiment, the receiving device conforming to the first communication protocol uses the long training sequence of the legacy communication protocol as described above with respect to FIG. 23 in one embodiment to first cross- Detect whether the data unit including the preamble 4200 conforms to the HEW communication protocol by performing the second cross-correlation of the L_LTF field 2916 using the correlation and the modified long training sequence of the first communication protocol. can do.

43 is a diagram of a portion 4300 of an example PHY preamble conforming to a first communication protocol according to another embodiment as compared to a portion 2904 of a preamble conforming to the legacy protocol. Additionally, the PHY preamble 4300 also corresponds to a range extension mode of the first communication protocol. 43 also includes a diagram of a portion 4304 of an example PHY preamble conforming to a first communication protocol according to another embodiment as compared to a portion 2904 of a preamble conforming to the legacy protocol. Additionally, the PHY preamble 4304 also corresponds to the normal mode of the first communication protocol.

In one embodiment, the network interface device 16 of the AP 14 is a data unit including a PHY preamble 4300 or a PHY preamble 4304 to the client station 25-1 via OFDM modulation according to an embodiment. is configured to generate and transmit In one embodiment, the network interface device 27 of the client station 25 - 1 determines whether the data unit comprising the preamble 4300 or the preamble 4304 conforms to the first communication protocol using techniques discussed below. is configured to determine whether or not In one embodiment, the network interface device 27 of the client station 25-1 determines whether the data unit comprising the preamble 4300 conforms to the range extension mode and determines the preamble 4304 using techniques discussed below. and determine whether the containing data unit conforms to the regular mode.

In one embodiment, the network interface device 27 of the client station 25 - 1 is also configured to generate and transmit data units including the PHY preamble 4300 or the PHY preamble 4304 to the AP 14 . In one embodiment, the network interface device 16 of the AP 14 uses the techniques discussed below to determine whether the data unit including the PHY preamble 4300 or the PHY preamble 4304 conforms to the first communication protocol. is configured to determine In one embodiment, the network interface device 16 of the AP 14 determines whether the data unit including the preamble 4300 conforms to the range extension mode and the data including the preamble 4304 using techniques discussed below. and determine whether the unit conforms to the regular mode.

According to one embodiment, the data unit including the PHY preamble 4300 conforms to the first communication protocol and occupies a 20 MHz bandwidth. Data units comprising a similar preamble in preamble 4300 and conforming to the first communication protocol may use other suitable bandwidths, such as, for example, 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz, or in other embodiments, other suitable bandwidths. can occupy According to one embodiment, the data unit including the PHY preamble 4304 conforms to the first communication protocol and occupies a 20 MHz bandwidth. Data units comprising a similar preamble in preamble 4304 and conforming to the first communication protocol may use other suitable bandwidths, such as, for example, 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz, or in other embodiments, other suitable bandwidths. can occupy

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

The data unit 4300 is the data unit 2900 of FIG. 29 except that the data unit 4300 omits the second (replica) L-Sig field 2928 and includes an auto-sensing OFDM symbol 4308 . ) is similar to In one embodiment, the receiving device conforming to the first communication protocol determines whether the data unit comprising the preamble 4300 conforms to the first communication protocol based on detecting the auto-sensing OFDM symbol 4308 in the preamble 4300 . can detect whether In the illustrated embodiment the auto-sensing symbol 4308 is immediately after the L-Sig field 206/306/506. The auto-sensing symbol 4308 is aligned to its corresponding OFDM symbol in the legacy data unit format 2904 and is modulated using BPSK modulation in one embodiment. In one embodiment, the receiving device conforming to the first communication protocol is a data unit including the preamble 4300 based on detecting the auto-sensing OFDM symbol 4308 in the preamble 4300 as discussed with respect to FIG. 37 . It can detect whether the first communication protocol is followed.

The preamble 4304 is similar to the preamble 4104 of FIG. 41 and like-numbered elements are not discussed in detail for purposes of brevity. In one embodiment, L_LTF field 4112 corresponds to modified LTF field 2304 of FIG. 23 , and in one embodiment, L-SIG 4120 corresponds to modified legacy signal field 2306 of FIG. 23 . do. In this embodiment, the receiving device conforming to the first communication protocol uses the long training sequence of the legacy communication protocol as described above with respect to FIG. 23 in one embodiment to first cross- Whether the data unit including the preamble 4304 conforms to the first communication protocol by performing a second cross-correlation of the L_LTF field 4112 using the correlation and the modified long training sequence of the first communication protocol. can detect In a similar manner, a receiving device conforming to the first communication protocol may sense whether the data unit including the preamble 4304 conforms to the regular 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. 23 . do. In this embodiment, the receiving device conforming to the HEW protocol uses the long training sequence of the legacy communication protocol as described above with respect to FIG. 23 in one embodiment to perform the first cross-correlation of the L-LTF 2912 . 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 whether the data unit including the preamble 4300 conforms to the first communication protocol. can

In various other embodiments, techniques such as those described above with respect to Figures 9a-28 allow a receiver conforming to a first communication protocol to i) determine whether a data unit conforms to the first communication protocol, and ii) As described above with respect to Figures 29-40B utilized to enable determining which of a variety of different modes (eg, range extension mode, regular mode, etc.) of the first communication protocol a data unit conforms to. combined with the same techniques.

In some embodiments where the Sig field is duplicated (eg, L-SIG, HEW-SIG1, etc.), time varying tone mapping is utilized. For example, in one embodiment, a half bandwidth cyclic shift tone mapper is used. In one embodiment, the tones on the first SIG OFDM symbol (time t1) are:

(방정식 4).

(Equation 4).

, 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 tones on the second (replica) SIG OFDM symbol (time t ₂ ) are:

(방정식 5)

(Equation 5)

, where N is the number of tones in the SIG OFDM symbol. Thus, in one embodiment, BPSK symbols s are mapped sequentially to tones in a first SIG OFDM symbol, while identical BPSK symbols s are cyclically for half of the tones in a second SIG OFDM symbol. (cyclically) shifted. In other embodiments, another suitable time varying tone is utilized to achieve time diversity across different SIG OFDM symbols.

In one embodiment, time diversity across different SIG OFDM symbols is implemented using different interleavers for identically coded bits on the two OFDM symbols. In other embodiments, other suitable techniques for implementing time diversity across different SIG OFDM symbols are utilized.

In some embodiments in which the preamble conforms to the first communication protocol, the L-Sig field in the preamble conforms to the first communication protocol corresponds to the L-SIG in the legacy preamble multiplied by the sequence ck:

(방정식 6)

(Equation 6)

Here, k is the tone index. In one embodiment, the sequence c _k is a sequence with values of ±1.

In some embodiments, one or more additional L-Sig fields are included in the preamble conforming to the first communication protocol.

In some embodiments, the HEW-Sig field contains data unit duration information, such as a number of bytes in a data unit, a number of OFDM symbols in a data unit, and the like.

In some embodiments, including a copy of the HEW-Sig field in the preamble causes the legacy device (eg, IEEE 802.11ac receiver) to generate a SIGA CRC error with a 100% probability of the Sig field in the legacy preamble (eg For example, the HEW-Sig field corresponding to SIGA) is configured. For example, in various embodiments, the bits in the HEW-Sig field are scrambled and 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 bits corresponding to invalid modes in the legacy protocol.

In one embodiment, a method for generating a physical layer (PHY) data unit for transmission over a communication channel, the PHY data unit conforming to a first communication protocol. The method comprises, in a first communication device, generating a PHY preamble for the PHY data unit, wherein generating the PHY preamble comprises: generating a signal field, including a signal field and a copy of the signal field in the PHY preamble and determining a duration of the PHY data unit based on the first portion of the PHY preamble, wherein the first portion of the PHY preamble conforms to a second communication protocol, but does not conform to the first communication protocol. and formatting the PHY preamble to be decodable by the communication device. The method also includes generating, at the first communication device, the PHY data unit including the PHY preamble and a PHY payload.

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

the signal field is a legacy signal field decodable by the second communication device; the legacy signal field is included in the first part of the PHY preamble; and the legacy signal field includes information indicating a duration of the PHY data unit.

Generating the PHY preamble for the PHY data unit further comprises: generating an additional signal field conforming to the second communication protocol, and including the additional signal field in a second portion of the PHY preamble do.

The second portion of the PHY preamble is not decodable to the second communication device.

Generating the PHY preamble for the PHY data unit further comprises: including a copy of the additional signal field in a second portion of the PHY preamble.

Generating the PHY preamble for the PHY data unit further comprises: including a copy of the additional signal field in a second portion of the PHY preamble.

the signal field is a first signal field; and generating the PHY preamble for the PHY data unit comprises: generating a second signal field decodable by the second communication device, the second signal field indicating a duration of the PHY data unit generating the second signal field comprising information; including the second signal field in a first portion of the PHY preamble; and including the first signal field in a second portion of the PHY preamble.

The second portion of the PHY preamble is not decodable to the second communication device.

the PHY preamble for the PHY data unit is generated by including a respective first guard interval between orthogonal frequency domain (OFDM) symbols in a first portion of the PHY preamble; and the method further comprises generating, at the first communication device, the PHY payload including a respective second guard interval between OFDM symbols in the PHY payload, wherein each second guard interval is It has a longer duration than each first guard interval.

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

In another embodiment, a first communication device comprises a network interface device having one or more integrated circuits, wherein the one or more integrated circuits: generate a physical layer (PHY) preamble for the PHY data unit conforming to a first communication protocol wherein generating the physical layer preamble comprises generating a signal field, including a signal field and a copy of the signal field in a PHY preamble, and a duration of the PHY data unit based on the first portion of the PHY preamble. and format the PHY preamble so that the first portion of the PHY preamble conforms to a second communication protocol, but is decodable by a second communication device that does not conform to the first communication protocol to determine The one or more integrated circuits are also configured to generate the PHY data unit including the PHY preamble and the PHY payload.

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

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

The one or more integrated circuits are configured to generate an additional signal field conforming to the second communication protocol, and include the additional signal field in the second portion of the PHY preamble.

The second portion of the PHY preamble is not decodable to the second communication device.

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

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

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

The second portion of the PHY preamble is not decodable to the second communication device.

the one or more integrated circuits include a respective first guard interval between orthogonal frequency domain (OFDM) symbols in a first portion of the PHY preamble to generate the PHY preamble for the PHY data unit; and a respective second guard interval between OFDM symbols in the PHY payload to generate the PHY payload, each second guard interval having a longer duration than each first guard interval. .

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

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

When implemented in hardware, the hardware may include one or more of discrete components, integrated circuits, application-specific integrated circuits (ASICs), programmable logic devices (PLDs), and the like.

Although the invention has been described with reference to specific examples, which are illustrative only and not intended as limitations of the invention, changes, additions, and/or deletions may be made to the disclosed embodiments without departing from the scope of the invention. there is.

Claims (20)

A method for generating a physical layer (PHY) data unit for transmission over a communication channel, the PHY data unit conforming to a first communication protocol, the method comprising:
generating, in a first communication device, a PHY preamble for the PHY data unit;
generating a first orthogonal frequency division multiplexing (OFDM) symbol of the PHY preamble that includes a legacy signal field;
generating a second OFDM symbol of the PHY preamble that includes a copy of the legacy signal field, the second OFDM symbol being transmitted after the first OFDM symbol, and a copy of the legacy signal field in the second OFDM symbol the presence of indicates to second communication devices conforming to the first communication protocol that the PHY data unit is conforming to the first communication protocol, and
To determine a duration of the PHY data unit based on the first portion of the PHY preamble, the first portion of the PHY preamble including the first OFDM symbol conforms to a second communication protocol, but generating the PHY preamble, comprising formatting the PHY preamble to be decodable by a third communication device that does not conform to the first communication protocol; and
generating, at the first communication device, the PHY data unit including the PHY preamble and a PHY payload. The method according to claim 1,
the legacy signal field is decodable by the third communication device;
The legacy signal field includes information indicating a duration of the PHY data unit. 3. The method of claim 2, wherein generating the PHY preamble for the PHY data unit comprises:
generating an additional signal field conforming to the first communication protocol; and
and including the additional signal field in a third OFMD symbol of the second portion of the PHY preamble. 4. The method of claim 3, wherein the second portion of the PHY preamble is not decodable to the third communication device. 4. The method of claim 3, wherein generating the PHY preamble for the PHY data unit comprises:
and including a copy of the additional signal field in a fourth OFMD symbol of the second portion of the PHY preamble. The method of claim 1, wherein generating the PHY preamble for the PHY data unit comprises:
and including a copy of the legacy signal field in a second portion of the PHY preamble that cannot be decoded by a third communication device that does not conform to the first communication protocol. delete delete The method according to claim 1,
the PHY preamble for the PHY data unit is generated by including a respective first guard interval between orthogonal frequency domain (OFDM) symbols in a first portion of the PHY preamble; and
The method further comprises generating, at the first communication device, the PHY payload including a respective second guard interval between OFDM symbols in the PHY payload, wherein each second guard interval is each having a longer duration than the first guard interval of 10. The method of claim 9, wherein the PHY preamble for the PHY data unit is generated by including a respective second guard interval between OFDM symbols in a second portion of the PHY preamble. A first communication device, comprising:
A network interface device having one or more integrated circuits, the one or more integrated circuits comprising:
generating a physical layer (PHY) preamble for a PHY data unit conforming to a first communication protocol, wherein generating the PHY preamble comprises:
generating a first orthogonal frequency division multiplexing (OFDM) symbol of the PHY preamble that includes a legacy signal field;
generating a second OFDM symbol of the PHY preamble that includes a copy of the legacy signal field, the second OFDM symbol being transmitted after the first OFDM symbol, and a copy of the legacy signal field in the second OFDM symbol the presence of indicates to second communication devices conforming to the first communication protocol that the PHY data unit is conforming to the first communication protocol, and
To determine a duration of the PHY data unit based on the first portion of the PHY preamble, the first portion of the PHY preamble including the first OFDM symbol conforms to a second communication protocol, but 1 comprising formatting the PHY preamble to be decodable by a third communication device that does not conform to a communication protocol; and
and generate the PHY data unit including the PHY preamble and PHY payload. 12. The method of claim 11,
the legacy signal field is decodable by the third communication device;
and the legacy signal field includes information indicating a duration of the PHY data unit. 13. The method of claim 12, wherein the one or more integrated circuits are
generate an additional signal field conforming to the first communication protocol; and
and include the additional signal field in a third OFMD symbol of the second portion of the PHY preamble. 14. The first communication device of claim 13, wherein the second portion of the PHY preamble is not decodable to the third communication device. 14. The method of claim 13, wherein the one or more integrated circuits are
and include a copy of the additional signal field in a fourth OFDM symbol of the second portion of the PHY preamble. 12. The method of claim 11, wherein the one or more integrated circuits are
and include a copy of the legacy signal field in a second portion of the PHY preamble that cannot be decoded by a third communication device that does not conform to the first communication protocol. delete delete 12. The method of claim 11, wherein the one or more integrated circuits are
include a respective first guard interval between orthogonal frequency domain (OFDM) symbols in a first portion of the PHY preamble to generate the PHY preamble for the PHY data unit; and
and generate the PHY payload including a respective second guard interval between OFDM symbols in the PHY payload, each second guard interval having a longer duration than each first guard interval; A first communication device. 20. The device of claim 19, wherein the one or more integrated circuits are configured to generate the PHY preamble including a respective second guard interval between OFDM symbols in a second portion of the PHY preamble.

Images