KR20160106123A - Physical layer frame format for wlan - Google Patents

Abstract

In a method for generating a physical layer (PHY) data unit for transmission over a communication channel, the PHY data unit conforms to a first communication protocol, and the first communication device generates a PHY preamble for the PHY data unit, And a second portion of the PHY preamble to determine a duration of the PHY data unit based on the first portion of the PHY preamble, Protocol, but formatting the PHY preamble to be decodable by a second communication device that does not comply with the first communication protocol. The first communication device generates a PHY data unit including a PHY preamble and a PHY payload.

Description

[0001] PHYSICAL LAYER FRAME FORMAT FOR WLAN [0002]

See related application

This disclosure is continuation in part (CIP) of U.S. Patent Application Serial No. 14 / 523,678 entitled " Range Extension Mode for WiFi ", filed October 24, US patent application entitled " Range Extension PHY " Patent application number. 61 / 895,591, filed on January 9, 2014, and U.S. Pat. Patent application number. 61 / 925,332, filed on March 10, 2014, and U.S. Pat. Patent application number. 61 / 950,727, filed May 2, 2014, and U.S. Pat. Patent application number. 61 / 987,778, the disclosures of which are incorporated herein by reference in their entirety.

In addition, this disclosure is incorporated by reference in its entirety for all purposes, such as U.S. Pat. Patent application number. 61 / 924,467 filed on January 29, 2014, entitled " Physical Layer Frame Format for WLAN " Patent application number. 62 / 030,426, filed on August 7, 2014, entitled " Physical Layer Frame Format for WLAN " Patent application number. 62 / 034,509 filed on September 3, 2014, entitled " Physical Layer Frame Format for WLAN " Patent application number. 62 / 045,363, filed on September 17, 2014, entitled " Physical Layer Frame Format for WLAN " Patent application number. 62 / 051,537, filed on December 8, 2014, and U. S. Patent Application Serial No. 60 / Patent application number. 62 / 089,032, the disclosures of which are incorporated herein by reference in their entirety.

Field of disclosure

Field of the Invention The present invention relates generally to wireless communication networks, and more particularly to physical layer (PHY) frame formats capable of coexisting 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 last 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 Mbps (megabits per second), the IEEE 802.11a and 802.11g standards specify a single user peak throughput of 54 Mbps, the IEEE 802.11n standard specifies 600 Mbps, and the IEEE 802.11ac standard specifies a single user peak throughput in the gigabits per second (Gbps) range. Future standards are likely to provide much larger 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 includes generating a PHY preamble for the PHY data unit in a first communication device, the step of generating the PHY preamble includes generating a signal field, generating a replica of the signal field and the signal field with the PHY preamble And wherein the first portion of the PHY preamble follows a second communication protocol to determine the duration of the PHY data unit based on the first portion of the PHY preamble, And formatting the PHY preamble so as to be decodable by the second communication device. The method also includes, at the first communication device, generating 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 a first portion of the PHY preamble; And the legacy signal field includes information indicating the duration of the PHY data unit.

The step of generating the PHY preamble for the PHY data unit further comprises generating an additional signal field compliant with 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 by the second communication device.

Generating the PHY preamble for the PHY data unit further comprises: including a replica 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 replica 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, wherein the second signal field is used to indicate the PHY data unit to a duration Generating a second signal field, the second signal field including 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 by the second communication device.

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

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

In another embodiment, a first communication device includes a network interface device having one or more integrated circuits, wherein the one or more integrated circuits are configured to: generate a physical layer (PHY) preamble for the PHY data unit compliant with a first communication protocol Wherein generating the physical layer preamble includes generating a signal field, including a replica of the signal field and the signal field in the PHY preamble, and generating a PHY data preamble based on the first portion of the PHY preamble, And formatting the PHY preamble so that a first portion of the PHY preamble follows a second communication protocol to determine a duration of the PHY preamble but is decodable by a second communication device that does not conform to the first communication protocol. The one or more integrated circuits are also configured to generate the PHY data unit comprising 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; Wherein 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 the 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 to include the additional signal field in a second portion of the PHY preamble.

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

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

The one or more integrated circuits are configured to include a replica of the additional signal field in a 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, wherein the second signal field includes information indicating a duration of the PHY data unit, and wherein the first signal field of the PHY preamble Said second signal field being included in said portion; And to include the first signal field in a second portion of the PHY preamble.

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

Wherein the one or more integrated circuits include an individual 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 PHY payload comprising an individual second guard interval between OFDM symbols in the PHY payload, wherein each second guard interval has a duration that is longer than a respective first guard interval .

The one or more integrated circuits are configured to generate the PHY preamble including an individual 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), in accordance with one embodiment.
Figures 2a and 2b are diagrams of a data unit format of the prior art.
Figure 3 is a diagram of another prior art data unit format.
4 is a diagram of another prior art data unit format.
Figure 5 is a diagram of another prior art data unit format.
6A is a group of modulation diagrams used to modulate symbols in a data unit of the prior art.
FIG. 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 multiplex (OFDM) data unit according to one embodiment.
Figure 7b is a group of modulation diagrams used to modulate the symbols in the data unit depicted in Figure 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 according to an exemplary embodiment is used for a preamble of a data unit.
9B is a diagram illustrating an example data unit in which the regular coding scheme according to one embodiment is used only for a portion of the preamble of the data unit.
10A is a diagram illustrating an example data unit in which a tone spacing adjustment according to an embodiment is used in combination with block coding.
FIG. 10B is a diagram illustrating an example data unit in which tone spacing according to another embodiment is used in combination with block coding. FIG.
11A is a diagram illustrating a regular mode data unit according to one embodiment.
11B is a diagram illustrating a range extension mode data unit according to an embodiment.
Figures 12a-12b are diagrams that separately illustrate two possible formats of a long training field according to two exemplary embodiments.
FIG. 13A is a diagram illustrating a non-legacy signal field of the normal mode data unit of FIG. 11A according to one embodiment.
FIG. 13B is a diagram illustrating a non-legacy signal field of the extended range mode data unit of FIG. 11B in accordance with one embodiment.
14A is a diagram illustrating a range extended mode data unit according to an embodiment.
14B is a diagram illustrating a legacy signal field of the range extended mode data unit of FIG. 14A according to one embodiment.
14C is a diagram illustrating a Fast Fourier Transform (FFT) window for the legacy signal field of FIG. 14B in a legacy receiving device according to one embodiment.
15 is a block diagram illustrating a format of a non-legacy signal field in accordance with one embodiment.
16 is a block diagram illustrating an example PHY processing unit for generating normal mode data units using a regular coding scheme according to one embodiment.
17A is a block diagram of an example PHY processing unit for generating range extended 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 extended mode data units according to another embodiment.
18A is a block diagram of an example PHY processing unit for generating range extended 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 extended mode data units according to another embodiment.
19A is a block diagram of an example PHY processing unit for generating range extended mode data units according to another embodiment.
19B is a block diagram of an example PHY processing unit for generating range extended mode data units according to another embodiment.
20A is a diagram illustrating repetition of OFDM symbols in a preamble of a ranging extended mode data unit according to an embodiment.
FIG. 20B is a diagram illustrating repetition of OFDM symbols in a preamble of a ranging extended 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 showing an iterative technique for OFDM symbols according to another embodiment.
21 is a flowchart of an exemplary method for generating a data unit according to an embodiment.
22A is a diagram of a 20 MHz full bandwidth with repeats of a range extended data unit having a 10 MHz subband in accordance with one embodiment.
22B is a diagram of a 40 MHz full bandwidth with repeats of a range extended data unit having a 10 MHz subband in accordance with one embodiment.
22C is a diagram of an exemplary tone plan for a 32-FFT mode according to one embodiment.
23 is a diagram of an example data unit in which a laser enhancement mode according to an embodiment is used for a preamble of a data unit.
24 is a block diagram of an example PHY processing unit for generating range extended mode data units according to another embodiment.
25A is a diagram of an exemplary 20 MHz full bandwidth with ½ tone spacing in accordance with one embodiment.
25B is a diagram of an exemplary 20 MHz full bandwidth with ½ tone spacing, in accordance with one embodiment.
26A is a diagram of a non-legacy tone plan for a range extended mode having a size 64 FFT and a ½ tone interval in accordance with one embodiment.
26B is a diagram of a non-legacy tone plan for a range extension mode having a size 128 FFT and a ½ tone spacing in accordance with one embodiment.
26C is a diagram of a non-legacy tone plan for a range extension mode having a size 256 FFT and a ½ tone spacing in accordance with one embodiment.
27 is a flow diagram of an exemplary method for generating a data unit in accordance with one embodiment.
28 is a flowchart of an exemplary method for generating a data unit according to another embodiment.
29 is a diagram of an example PHY preamble portion following a first communication protocol, in accordance with one embodiment, compared to a preamble portion conforming to a legacy protocol.
FIG. 30 is a diagram of another exemplary PHY preamble portion following a first communication protocol, according to another embodiment, compared to a preamble portion conforming to a legacy protocol.
31 is a diagram of another example PHY preamble portion following a first communication protocol according to another embodiment compared to a preamble portion conforming to a legacy protocol.
32 is a diagram of another example PHY preamble portion following a first communication protocol according to another embodiment compared to a preamble portion conforming to a legacy protocol.
33 is a diagram of another exemplary PHY preamble portion following a first communication protocol according to another embodiment compared to a preamble portion conforming to a legacy protocol.
34 is a diagram of another example PHY preamble portion following a first communication protocol, according to another embodiment compared to a preamble portion following a legacy protocol.
35 is a diagram of another example PHY preamble portion following a first communication protocol according to another embodiment compared to a preamble portion conforming to a legacy protocol.
36 is a diagram of another example PHY preamble portion following a first communication protocol according to another embodiment compared to a preamble portion conforming to a legacy protocol.
FIG. 37 is a diagram of another example PHY preamble portion following a first communication protocol, according to another embodiment compared to a preamble portion conforming to a legacy protocol.
Figures 38a-d are diagrams illustrating examples of auto detection symbols used with the example PHY preamble of Figure 37 according to various embodiments.
39 is a diagram of another exemplary PHY preamble portion following a first communication protocol according to another embodiment compared to a preamble portion conforming to a legacy protocol.
40A is a diagram of another example PHY preamble portion following a first communication protocol, according to another embodiment.
40B is a diagram of another example PHY preamble portion following a first communication protocol, according to another embodiment.
41 is a diagram of another exemplary PHY preamble portion following a normal mode of a first communication protocol as compared to a preamble portion compliant with a legacy protocol and another exemplary PHY preamble portion following a range extension mode of the first communication protocol, FIG.
FIG. 42 illustrates a diagram of another exemplary PHY preamble portion that follows the normal mode of the first communication protocol and another exemplary PHY preamble portion that follows the range extension mode of the first communication protocol, as compared to the preamble portion following the legacy protocol, FIG.
Figure 43 is a diagram of another exemplary PHY preamble portion following a normal mode of a first communication protocol as compared to a preamble portion compliant with a legacy protocol and another exemplary PHY preamble portion following a range extension mode of a first communication protocol, FIG.

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 client stations according to at least a first communication protocol. The first communication protocol is sometimes referred to in the present application 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 in accordance with one or more other communication protocols that define operations with the same frequency band as the HEW communication protocol but with overall lower data throughputs. Lower data throughput communication protocols (e.g., IEEE 802.11a, IEEE 802.11n, and / or IEEE 802.11ac) are collectively referred to herein as " legacy " In at least some embodiments, the legacy communication protocols are typically located in indoor communication channels, and the HEW communication protocol includes at least occasional outdoor communication, extended range communication, or reduced signal-to-noise ratios (SNR) Lt; RTI ID = 0.0 > regions. ≪ / RTI >

According to one embodiment, the symbols transmitted by the AP are generated according to a range extension coding scheme that provides increased redundancy of symbols or encoded information bits in symbols. Duplication increases the likelihood of symbols that are successfully decoded by devices that receive symbols from the AP within areas with a particularly reduced SNR. The amount of redundancy required to mitigate the reduced SNR is typically dependent on delay channel spread (e.g., 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 normal mode and a range extension mode. The normal mode is typically used with communication channels characterized by shorter channel delay spreads (e.g., indoor communication channels) or generally higher SNR values, and the range extended mode is generally used in relatively small increments Is used with communication channels characterized by longer channel delay spreads (e.g., outdoor communication channels) or generally lower SNR values. In one embodiment, the regular coding scheme is used in normal mode, and the range extension coding scheme is used in the range extended mode.

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

In another embodiment, the preamble used in the range extension mode is formatted differently from the preamble used in the normal mode. For example, the preamble used in the range extended mode is formatted so that the receiving device can automatically detect (e.g., before decoding) that the data unit corresponds to the range extended mode. In one embodiment, when the receiving device senses that the data unit is in the range extended mode, the receiving device uses the data extension of the data unit using the range extension coding technique, and in at least some embodiments, at least the portion of the preamble As well as 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 one embodiment. The receiving device then decodes at least the data portion of the data unit using a regular coding scheme in one embodiment.

In addition, in at least some embodiments, the preamble of a data unit in normal mode and / or range extension mode is not a HEW communication protocol, but a client station operating in accordance with a legacy protocol has a specific Information can be determined, and / or the data unit is formatted so as not to conform to the legacy protocol. Additionally, the preamble of the data unit may be formatted such that the client station operating in accordance with the HEW protocol is able to determine whether the data unit conforms to the HEW communication protocol and whether the data unit is formatted according to the normal mode or range extension mode in one embodiment. do. Similarly, in one embodiment, a client station configured to operate in accordance with the HEW communication protocol also transmits data units as described above.

In at least some embodiments, the data units formatted as described above have an AP configured to operate with client stations, for example, in accordance with a plurality of different communication protocols, and / or a plurality of client stations Having WLANs operating according to different communication protocols is useful. In the above example, communication devices configured to operate according to both the HEW communication protocol (including normal mode and range extension mode) and the legacy communication protocol continue to operate in accordance with the HEW communication protocol rather than the legacy communication protocol It can be determined that the data unit has been formatted and that the data unit is formatted according to the range extension mode instead of the normal mode. Similarly, a communication device configured to operate in accordance with 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 the 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 the network interface 16. The network interface 16 includes a medium access control (MAC) processing unit 18 and a physical layer (PHY) processing unit 20. The PHY processing unit 20 includes a plurality of transceivers 21 and the transceiver 21 is coupled to a plurality of antennas 24. Although three transceivers 21 and three antennas 24 are illustrated in FIG. 1, the AP 14 may be a transceiver of other suitable numbers (e.g., 1, 2, 4, 5, etc.) (21) and antennas (24). In one embodiment, the MAC processing unit 18 and the PHY processing unit 20 operate in accordance with a first communication protocol (e.g., a HEW communication protocol) that includes at least a first mode and a second mode of a first communication protocol . In some embodiments, the first mode may be a range extension coding technique (e.g., block encoding, bit-wise replication, or symbol replication), a signal modulation technique (e.g., The present invention corresponds to a range extension mode using both phase shift keying or quadrature amplitude modulation or both a range extension coding technique and a signal modulation technique. (SNR) ratio when successful decoding of PHY data units according to the extended mode is performed, as compared to the normal mode using the normal coding technique. In embodiments, the range extended mode may be a data transmission mode in order to achieve successful decoding with an increased range and / or a reduced SNR ratio as compared to the normal mode. In another embodiment, the MAC processing unit 18 and the PHY processing unit 20 are also configured to operate in accordance with a second communication protocol (e.g., the IEEE 802.11ac standard). In another embodiment The MAC processing unit 18 and the PHY processing unit 20 may additionally include a second communication protocol, a third communication protocol, and / or a fourth communication protocol (e.g., an IEEE 802.11a standard and / or an IEEE 802.11n standard) As shown in FIG.

The WLAN 10 includes a plurality of client stations 25. Although four client stations 25 are illustrated in FIG. 1, the WLAN 10 may be used in various scenarios and embodiments, such as client stations of other suitable numbers (e.g., 1, 2, 3, 5, 6, (25). At least one of the client stations 25 (e.g., client station 25-1) is configured to operate in accordance with at least a first communication protocol. In some embodiments, at least one of the client stations 25 is not configured to operate in accordance with the first communication protocol, but a second communication protocol, a third communication protocol, and / or a fourth communication protocol Quot;). ≪ / RTI >

The client station 25-1 includes a host processor 26 coupled to the 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 and the transceiver 30 is 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 used in other embodiments with other suitable numbers (e.g., 1, 2, 4, 5, ) Transceivers 30 and antennas 34. The transceivers 30 of FIG.

According to an embodiment, the client station 25-4 is a legacy client station, i. E. The client station 25-4 receives data transmitted by the AP 14 or another client station 25 according to a first communication protocol The unit is received and can not be fully decoded. Similarly, according to the embodiment, the legacy client station 25-4 can not receive data units according to the first communication protocol. On the other hand, the legacy client station 25-4 receives and completely decodes and transmits data units in accordance with 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 the embodiment, the client station 25-4 has a structure similar to that of the client station 25-1. In these embodiments, a client station 25 having the same or similar structure as the client station 25-1 has the same or different numbers of transceivers and antennas. For example, client station 25-2 has only two transceivers and two antennas (not shown), depending on the 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 are configured to transmit the data units generated via the antenna (s) 24. Similarly, transceiver (s) 21 are configured to receive data units via antenna (s) 24. The PHY processing unit 20 of the AP 14 processes the received data units according to the first communication protocol and with the following described formats according to various embodiments and determines that these data units conform to the first communication protocol .

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 in the present application. The transceiver (s) 30 are configured to transmit the data units generated via the antenna (s) 34. Similarly, transceiver (s) 30 are configured to receive data units via antenna (s) The PHY processing unit 29 of the client device 25-1 is adapted to process the received data units according to the first communication protocol and having the following described formats in accordance with various embodiments, Lt; RTI ID = 0.0 > communication protocol. ≪ / RTI >

Figure 2a is a diagram of a prior art OFDM data unit 200 configured to transmit AP 14 to orthogonal frequency division multiplexing (OFDM) modulation to legacy client station 25-4, according to an embodiment. In an embodiment, legacy client station 25-4 is also configured to transmit data unit 200 in accordance with one embodiment to AP 14. [ The data unit 200 conforms to the IEEE 802.11a standard and occupies the 20 megahertz (MHz) band. The data unit 200 includes a legacy short training field (L-STF) 202, typically used for packet detection, initial synchronization, and automatic gain control, and the like, And a legacy long training field (L-LTF) The data unit 200 also includes a legacy signal field 202 that is used to carry certain physical layer (PHY) parameters of the data unit 200, such as, for example, the modulation type and coding rate used to transmit the data unit. (L-SIG) < / RTI > The data unit 200 also includes a data portion 208. 2B is a diagram of an exemplary data portion 208 (which is not low density parity-check encoded) that, as required, includes a service field, a scrambled physical layer service data unit (PSDU), tail bits, . The data unit 200 is designed for transmission over one spatial or space-time stream in a single-input single-output (SISO) channel configuration.

Figure 3 is a diagram of a prior art OFDM data unit 300 configured to transmit AP 14 to legacy client station 25-4 via Orthogonal Frequency Division Multiplexing (OFDM) modulation, in accordance with an embodiment. In an embodiment, the legacy client station 25-4 is also configured to transmit to the AP 14 a data unit 300 according to one embodiment. The data unit 300 conforms to the IEEE 802.11n standard, occupies the 20 MHz band, and includes mixed mode situations, i.e., when the WLAN includes one or more client stations that conform to the IEEE 802.11a standard but do not conform to the IEEE 802.11n standard For example. The data unit 300 includes an L-STF 302, an L-LTF 304, an L-SIG 306, a high throughput signal field HT-SIG 308, a high throughput short training field HT- (MIMO) channel configuration in a multiple-input multiple-output (MIMO) channel configuration, and a data preamble having a plurality of data high throughput long training fields (HT-LTFs) ) ≪ / RTI > In particular, according to the IEEE 802.11n standard, a data unit 300 includes two HT-LTFs 312 if the data unit 300 is transmitted using two spatial streams, and four HT-LTFs 312 312 are transmitted using three or four spatial streams. An indication of the specific number of spatial streams 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 configured to transmit AP 14 to orthogonal frequency domain multiplexing (OFDM) modulation to legacy client station 25-4, in accordance with an embodiment. In an embodiment, legacy client station 25-4 is also configured to transmit data unit 400 to AP 14. [ Data unit 400 conforms to the IEEE 802.11n standard and occupies the 20 MHz band and does not include any client stations that conform to the " Greenfield " situations, i.e., the WLAN compliant with the IEEE 802.11a standard, n standard client stations. The data unit 400 includes a high throughput green field short training field (HT-GF-STF) 402, a first high throughput long training field HT-LTF1 404, an HT-SIG 406, Data HT-LTFs 408, where M is 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 configured to transmit AP 14 to orthogonal frequency domain multiplexing (OFDM) modulation to legacy client station 25-4, according to an embodiment. In an embodiment, legacy client station 25-4 is also configured to transmit data unit 500 to AP 14. [ The 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 in scenarios, a data unit similar to the data unit 500 occupies a different bandwidth, such as 40 MHz, 80 MHz, or 160 MHz bandwidth. The data unit 500 includes an L-STF 502, an L-LTF 504, an L-SIG 506, a first ultra high throughput signal field VHT-SIGA1 508-1, (VHT-SIGAs) 508 including a first high throughput signal field (VHT-SIGA2) 508-2, an ultra high throughput short training field (VHT-STF) 510, (VHT-LTFs) 512 (where M is an integer), and a second ultra high throughput signal field (VHT-SIG-B) The data unit 500 also includes a data portion 516.

6A is a set of diagrams illustrating the modulation of the L-SIG, HT-SIG1, and HT-SIG2 fields of the data unit 300 of FIG. 3, as defined by the IEEE 802.11n standard. The L-SIG fields are modulated according to Binary Phase Shift Keying (BPSK), while the HT-SIGl and HT-SIG2 fields are modulated according to BPSK but not on the orthogonal 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 the 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 the modulation 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.

FIG. 7A is a diagram of an OFDM data unit 700 configured for AP 14 to transmit to client station 25-1 via Orthogonal Frequency Division Multiplexing (OFDM) modulation, in accordance with one embodiment. In an embodiment, client station 25-1 is also configured to transmit data unit 700 to AP 14. [ The data unit 700 follows the first communication protocol and occupies a 20 MHz bandwidth. Data units conforming to a first communication protocol similar to the data unit 700 occupy other appropriate bandwidths, for example 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz, or in other embodiments, other appropriate bandwidths. The data unit 700 may be used in a " mixed mode " situations, i.e. a client station (e.g., a legacy client station 25-4) that conforms to the legacy communication protocol but does not conform to the first communication protocol, . The data unit 700, in some embodiments, is also used in other situations.

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

7A, data portion 700 includes one of each of L-STF 702, L-LTF 704, L-SIG 706, and HEW-SIGA1s 708. L-LTF 704, L-SIG 706, HEW-SIGA1 (702), L-STF 702, 708 are repeated, in one embodiment, over a corresponding number of 20 MHz sub-bands of the total bandwidth of the data unit. For example, in an embodiment, the OFDM data unit occupies an 80 MHz bandwidth and thus, in an embodiment, L-STF 702, L-STF 704, L-SIG 706, HEW- ), Respectively. In some embodiments, the modulation of the different 20 MHz sub-bandwidth signals is rotated by different angles. For example, in one embodiment, the first sub-band is rotated 0-, the second sub-band is rotated 90- degrees, the third sub-band is rotated 180- -. In other embodiments, different suitable rotations are used. The different phases of the 20 MHz sub-band signals cause, in at least some embodiments, a reduced peak-to-average power ratio (PAPR) of the OFDM symbols in the data unit 700. In the embodiment, HEW-STF, HEW-LTFs, HEW-SIGB and HEW data, if the data unit according to the first communication protocol occupies a cumulative bandwidth such as 20 MHz, 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz, Portion occupies the corresponding overall bandwidth of the data unit.

7B is a block diagram illustrating the 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. 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, Modulation has the same modulation. Therefore, 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 in the same way as the L-Sig field and the HEW-SIGA1 field, while the HEW-SIGA3 field is modulated in the L-Sig field, HEW- And the modulation of the HEW-SIGA2 field.

In an embodiment, the modulations of the L-SIG 706, HEW-SIGA1 708-1, and HEW-SIGA2 708-2 fields of the data unit 700 are based on data units conforming to the IEEE 802.11ac standard Legacy client stations configured to operate in accordance with the IEEE 802.11a standard and / or the IEEE 802.11n standard, in correspondence to the modulations of corresponding fields in the data unit 500 of FIG. 5, The client station according to the IEEE 802.11a standard will assume that the data unit 700 complies with the IEEE-802.11ac standard and will therefore process the data unit 700. For example, Will recognize the 802.11a standard and set the duration (or data unit duration) of the data unit in accordance with the duration indicated in the L-SIG 706. For example, according to one embodiment, the legacy client station 25 -4) SIG field 706 will yield a duration for the data unit based on the rate and length (e.g., as a number of bytes) displayed in the L-SIG field 706. In an embodiment, The rate and length of the data unit 700 are set such that the client station configured to operate in accordance with the legacy communication protocol is configured to calculate a packet duration T that corresponds to or at least approximates the actual duration of the data unit 700, For example, in one embodiment, the rate is set to indicate the lowest rate (i.e., 6 Mbps) defined by the IEEE 802.11a standard, the length being such that the packet duration computed using the lowest rate is at least equal to the data rate Is set to a value calculated to approximate the actual duration of the unit 700.

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

Similarly, a legacy client station configured to operate in accordance with the IEEE 802.11n standard, in one embodiment, is configured to receive, upon receiving the data unit 700, the rate and length indicated in the L-SIG 706 of the data unit 700, The packet duration T of the data unit 700 will be calculated. The legacy client station will detect the modulation of the first HEW signal field (HEW-SIGA1) 708-1 (BPSK) and assume that the data unit 700 is a legacy data unit compliant with the IEEE-802.11a standard. In an embodiment, the legacy client station will continue to decode the data unit 700, but will fail an error check (e.g., 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 the clear channel estimate (CCA). Thus, the communication medium will be protected from access by the legacy client station during the duration of the data unit 700, in an embodiment.

A legacy client station configured to operate in accordance with the IEEE 802.11ac standard rather than the first communication protocol is capable of receiving data units 700 at a rate indicated in the L-SIG 706 of the data unit 700, And calculate the packet duration T of the data unit 700 based on the length. However, in an embodiment, the legacy client station will not be able to detect that the data unit 700 does not conform to the IEEE 802.11ac standard, based on the modulation of the data unit 700. In some embodiments, one or more of the HEW signal fields (e.g., HEW-SIGA1 and / or HEW-SIGA2) of the data unit 700 may intentionally cause an error when the legacy client station decodes the data unit 700 And thus is configured to stop (or " drop ") decoding the data unit 700. For example, the HEW-SIGA 708 of the data unit 700 is formatted in one embodiment to deliberately 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 will drop the data unit 700 in an embodiment and before performing a clear channel estimation (CCA) For example, 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. [ Thus, the communication medium, in one embodiment, will be protected from access by the legacy client station for the duration of the data unit 700.

8 is a block diagram of an OFDM symbol 800 according to one embodiment. The data unit 700 of FIG. 7 includes OFDM symbols, e.g., 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 that repeats the end portion of the OFDM symbol. In one embodiment, the guard interval portion 802 includes a guard interval portion 802 that is a symbol interval between symbol segments resulting from multi-path propagation in a communication channel over some OFDM symbol 800 that is transmitted from a transmitting device (e.g., AP 14) Is used to minimize or eliminate interference and to ensure orthogonality of OFDM tones in the receiving device (e.g., client station 25-1). In one embodiment, the length of the guard interval portion 802 is selected based on the worst case channel delay spread in the communication channel between the transmitting device and the receiving device. For example, in one embodiment, the longer guard interval compared to the shorter guard interval, which is typically selected for indoor communication channels characterized by shorter channel delay spreads, is typically characterized by longer channel delay spreads For outdoor communication. In one embodiment, the length of the guard interval portion 802 is determined by the tone spacing (e.g., the spacing between sub-carrier frequencies of the full bandwidth of the data unit, as well as which information portion 804 was created) ). For example, a longer guard interval is selected (e.g., 256 tones) with a narrower tone interval compared to a shorter guard interval for a wider tone interval (e.g., 64 tones).

Depending on the transmission mode being used, the guard interval portion 802, according to one embodiment, corresponds to a short guard interval, a normal guard interval, or a long guard interval . 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 reasonably high SNR ratios, and the long guard interval is used 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 the HEW data unit (e.g., HEW data unit 700) when the HEW data unit is transmitted in normal mode, 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 extended 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 mu s. In other embodiments, the information portion 804 has an increased length corresponding to the tone interval at which the information portion 804 is generated. For example, if the information portion 804 has a first length of 3.2 mu s for a normal mode using a first tone interval of 64 tones and a second length of 6.4 mu s for a second tone interval of 128 tones, The two tone interval and the second length are both increased by an integer multiple of 2 compared to the first tone interval 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 (e. G., The information portion 804) Accept two copies). In other embodiments, other suitable lengths are used for SGI, NGI, LGI, and / or information portion 804. 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 intervals is used in a 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 indicative of < / RTI > For example, the normal mode for a 20 MHz bandwidth OFDM data unit uses a 64-point discrete Fourier transform (DFT) resulting in 64 OFDM tones (e.g., indices -32 to +31) Mode uses a 128-point DFT for a 20 MHz OFDM data unit resulting in 128 OFDM tones (e.g., indices -64 to +63) in the same bandwidth. In this case, the tone intervals in the range extended mode OFDM symbols are reduced by a factor of two (1/2) compared to the normal mode OFDM symbols while using the same tone plan. As another example, the normal mode for a 20 MHz bandwidth OFDM data unit uses 64-point discrete Fourier transform (DFT) resulting in 64 OFDM tones, while the range extended mode uses 20 MHz OFDM Use a 256-point DFT for the data unit. In this case, the tone interval in the range extended mode OFDM symbols is reduced by a factor of 4 (1/4) compared to the normal mode OFDM symbols. In these embodiments, for example, a long GI duration of 1.6 mu s is used. However, in one embodiment, the duration of the information portion of the extended-mode OFDM symbol is increased (e.g., from 3.2 μs to 6.4 μs), and the percentage of total OFDM symbol durations versus GI fraction durations remains the same do. Thus, in this case, efficiency loss is avoided due to the longer GI symbols in at least some embodiments. In various embodiments, the term " long guard interval " used in the present application 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 normal mode or a range extension mode according to an embodiment is used for a preamble of a data unit. The data unit 900 is generally the same as the data unit 700 of FIG. 7A and includes numbered elements, such as the data unit 700 of FIG. 7A. The HEW-SIGA field 708 (e.g., HEW-SIGA1 708-1 or HEW-SIGA2 708-2) of the data unit 900 includes a coding indication (CI) 902 The CI indication 902 is configured to indicate either (i) a regular mode with regular coding scheme or (ii) a range extended mode with range extended coding scheme. In some embodiments, the CI indication may be determined by a modulation and coding technique (e. G., A modulation scheme and a coding scheme) In an embodiment, for example, the normal mode corresponds to MCS values determined to be valid by the legacy receiver device (e.g., conforming to the IEEE 802.11ac protocol). And the range extension mode is enabled by the legacy receiver device The CI indication 902 corresponds to a determined (or unsupported) MCS value that does not comply with the IEEE 802.11ac protocol (e.g., does not comply with the IEEE 802.11ac protocol). In other embodiments, the CI indication 902 includes a plurality of normal mode MCS values and a plurality 9A, the regular coding scheme is used for all the OFDM symbols of the preamble of the data unit 700, and the range indicated by the CI indication 902 is < RTI ID = 0.0 > One of the enhancement coding or regular coding techniques is used for OFDM symbols in the data portion 716 in the illustrated embodiment.

In one embodiment, for example, when a range-extended coding scheme is used for OFDM symbols in the data portion 716, the range and / or SNR in the successful decoding of the PHY data units are compared to the regular data units, Improved (i. E., Successful decoding at longer range and / or lower SNR). In some embodiments, the improved range and / or SNR performance is not necessarily achieved for decoding the preamble 701 generated using a regular coding technique. In such embodiments, the transmission of at least the portion of the preamble 701 having the predetermined transmit power to increase the decoding range of the portion of the preamble 701 is greater than the transmit power used for the transmission of the data portion 716 Boosted. In some embodiments, the portion of the preamble 701 that is transmitted with a transmit power boost may include legacy fields such as L-STF 702, L-LTF 704, and L-SIG 708, and / - Includes 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 as the " unboosted " do. Is used in combination with the transmit power boost of L-STF 702, L-LTF 704, and / or L-SIG 706 in some embodiments. In other embodiments, the 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 according to one embodiment is used for a preamble portion of a data unit. The data unit 950 is configured such that the data unit 950 can determine whether the coding scheme indicated by the CI indication 902 is a preamble 751 applied to the OFDM symbols of the data portion 716 as well as OFDM symbols of the portion of the preamble 751. [ 9A, except that the data unit 900 of FIG. Particularly, in the illustrated embodiment, the regular coding scheme is used for the first portion 751-1 of the preamble 701, and one of the range extension coding scheme or normal coding scheme indicated by the CI indication 902 is data Is used for the OFDM symbols of the second portion 751-2 of the preamble 751 in addition to the OFDM symbols of the portion 716. [ Thus, the coding scheme indicated by the CI indication 902 skips the OFDM symbol corresponding to the HEW-STF 710 and is applied starting with the OFDM symbol corresponding to the HEW-LTF 712-1 in the illustrated embodiment . Skipping the HEW-STF 710 in at least some embodiments may be performed by decoding the CI indication 902 and prior to receiving such OFDM symbols using the coding scheme indicated by the CI indication 902, Allowing the device receiving the data unit 950 sufficient time to properly set up the receiver to begin decoding.

FIG. 10A is a diagram illustrating an example data unit 1000 in which OFDM tone interval adjustment is used in combination with bit and / or symbol repetition for a range extension coding technique, in accordance with one embodiment. The data unit 1000 may be configured such that when the CI indication 902 indicates that the range extension coding scheme is being used, the OFDM symbols of the data portion 716 are transmitted to the normal mode OFDM symbols < RTI ID = 0.0 > Is generally generated using OFDM modulation with a tone interval that is reduced relative to the tone interval used for the data unit 900 of FIG. 7A.

FIG. 10B is a diagram illustrating an example data unit 1050 in which OFDM tone interval adjustment is used in combination with bit and / or symbol repetition for a range extension coding technique, according to another embodiment. The data unit 1050 includes a data unit 1050 that includes a data unit 1050 that includes a CI indication 902 indicating that OFDDM symbols in the data portion 716 and the OFDM symbols in the second portion 751-2, Is generally the same as data unit 950 of FIG. 9B except that the symbols are generated using OFDM modulation with a reduced tone interval relative to the tone interval used for normal mode OFDM symbols of data unit 1050 Do. In the embodiment shown in FIG. 10A, the total bandwidth of 20 MHz includes a normal tone spacing and a guard interval and a tone interval reduced by 2 in the first portion 751-1 over the entire bandwidth, A long guard interval, and a 64-size FFT twice repeated. In some embodiments, the transmit power boost is applied to the first portion 751-1. In other embodiments, other multiples such as 4x, 8x, or other appropriate values are used for one or more of a reduced tone spacing, an increased guard interval, an increased symbol duration, or an increased iteration over the entire bandwidth .

In some embodiments, a different preamble format is used for range extension mode data units compared to the preamble used for normal mode data units. In such embodiments, the device receiving the data unit can automatically sense whether the data unit is a normal 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 normal mode data unit 1100 includes a normal mode preamble 1101. The normal mode preamble 1101 is generally the same as the preamble 701 of the data unit 700 of FIG. 7A. In one embodiment, 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 (e.g., HEW-SIGA1 1108-1 or HEW-SIGA2 1108-2) of the preamble 1101 includes a CI indication 1102. In one embodiment, the CI indication 1102 is set to indicate whether the range extension coding scheme or regular coding scheme is used for OFDM symbols in the data portion 716 of the data unit 1100. In one embodiment, the CI indication 1102 comprises one bit, the first value of the bit representing the regular coding scheme and the second value of the bit representing the range extension coding scheme. As will be 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 normal mode preamble and not an extended mode preamble Can be detected. In one embodiment, upon detecting that the preamble 1101 is a normal mode preamble, based on the CI indication 1102, the receiving device determines whether a range extended coding scheme or regular coding scheme was used for the OFDM symbols in the data portion 716 and Thereby determining whether to decode the data portion 716. [ In some embodiments, when the CI indication 1102 indicates that the range extension coding scheme is being used, the OFDM symbols (e.g., HEW-LTFs and HEW-SIGB) of the portion of preamble 1101 and the data portion The OFDM symbols of data unit 716 are generated using OFDM modulation with a smaller tone interval than the tone interval used for normal mode OFDM symbols of data unit 1050. [

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

In one embodiment, one or more symbols of the HEW-SIGAs 1152 may include QBPSK instead of BPSK, for example, to allow automatic detection between the normal mode and the range extension mode by a receiving device operating in accordance with the HEW communication protocol. . In one embodiment, for example, where the normal mode preamble includes two BPSK symbols and one Q-BPSK symbol after the L-SIG 706 field, the BPSK symbols of the range extension mode preamble and L And one Q-BPSK symbol after the -SIG 706 field. In one embodiment, for example, there are 48 data tones in each 64-FFT (20 MHz) when using a 4x bit-wise iteration of MCS0. In some embodiments, some bits, such as, for example, the signal bandwidth, the bits used to indicate the MCS value, or other suitable bits in the case of auto-sensing distinction between the extended and normal modes, SIGAs < / RTI >

The content of each L-SIG (s) 1154 is transmitted to the L-SIG (s) 1154 of the data unit 1150 in one embodiment, where the preamble 1151 includes one or more second L- 706 in Fig. In one embodiment, the receiving device receiving the data unit 1150 determines that the preamble 1151 corresponds to the range extension mode preamble by sensing the repetition (s) of the L-Sig fields 706,1154. Furthermore, in one embodiment, the rate subfield and length subfield of L-SIG 706 and, accordingly, the rate subfield (s) of second L-SIG (s) The subfield (s) are set to fixed (e.g., predetermined) values. In this case, upon detection of the repetition (s) of L-Sig fields 706, 1154 in one embodiment, the receiving device may receive a fixed Values. However, in some embodiments, at least the length subfields of the L-SIG 706, and hence the length fields of at least the second L-SIG (s) 1154, are not set to fixed values. For example, instead, in one embodiment, the length field is set to a value determined based on the actual length of the data unit 1150. In one such embodiment, the receiving device first decodes L-SIG 706 and then iterates the L-Sig fields 706,1154 using the value of the length subfield in L-SIG 706 (S). In another embodiment, the receiving device first senses the repetition (s) of the L-Sig fields 706,1154 and then determines the number of detected multiples of the L-Sig fields 706,1154 Use redundant information in a plurality of L-Sig fields 706, 1154 to combine L-Sig fields 706, 1154 and / or improve channel estimation.

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

In other embodiments, preamble 1151 omits the second L-SIG (s) 1154 but includes L-LTF2 1156. [ In this embodiment, the receiving device senses that the preamble 1151 is a range extension mode preamble by sensing the presence of L-LTF2 1156. [ Figures 12a-12b are diagrams illustrating two possible formats of LTFs suitable for use as L-LTF2 1156 in accordance with two exemplary embodiments. 12A, in a first exemplary embodiment, L-LTF2 1200 is configured in the same manner as L-LTF 704, i.e., in a legacy communication protocol (e.g., IEEE 802.11a / n / ac standard Lt; / RTI > Specifically, in the illustrated embodiment, L-LTF2 1200 includes two repetitions of a double guard interval (DGI) 1202 followed by a long training sequence 1204, 1206. Going 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 iteration of the long training sequence 1212, a second normal guard interval 1214, and a long training sequence 1216 ). ≪ / RTI >

Referring back to FIG. 11B, in one embodiment, the HEW-SIGA (s) 1152 is 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 of the normal 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 normal mode preamble 1101. In other embodiments, the number and / or content of the HEW-SIGAs 1152 is different from the number and / or content of the HEW-SIGA (s) 1108 of the normal mode preamble 1101. In one embodiment, the device receiving the data unit 1150 receives the HEW-SIGA (s) 1152 using a range extension coding technique based on the detection that the preamble 1151 corresponds to a range extension mode preamble And interprets the HEW-SIGA (s) 1152 properly defined for the range extension mode.

In one embodiment in which the preamble 1151 omits the L-SIG (s) 1154 and / or the L-LTF2 1156, the receiving device may receive the HEW-SIGA field using the range extension coding technique and the regular coding technique - Detecting whether a HEW-SIGA field in the preamble is generated using a range extension coding scheme or a regular coding scheme based on a correlation (auto-correlation), thereby detecting a preamble as a range extension mode preamble 1151 or a normal mode preamble 1101 ). ≪ / RTI > Figures 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 one embodiment. In the illustrated embodiment, the HEW-SIGA 1108 of the normal mode preamble 1101 includes a first NGI 1302, a first HEW-SIGA field 1304, a second NGI 1306, and a second HEW- Field 1308. < / RTI > On the other hand, the HEW-SIGA 1152 of the range extension mode preamble 1151 includes a first LGI 1310, a first HEW-SIGA field 1312, a second LGI 1314, and a second HEW- 1312). In one embodiment, the receiving device performs a first autocorrelation of the HEW-SIGA field using a normal guard interval structure, e.g., the structure illustrated in Figure 13A, and uses a long guard interval structure, e.g., the structure illustrated in Figure 13b To perform a second auto-correlation, and auto-correlation results perform the comparison. In one embodiment, if the autocorrelation of the HEW-SIGA field using the long guard interval produces a larger result compared to the result of 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 autocorrelation of the HEW-SIGA field using the normal guard interval as compared to the result of the autocorrelation of the HEW-SIGA field with the long guard interval produces a larger result, then the receiving device It is determined that the preamble corresponds to the normal mode preamble 1101. [

Referring again to FIG. 11B, in one embodiment, the preamble 1151 is formatted such that the legacy client station can determine the duration of the data unit 1150 and / or the data unit does not conform to the legacy communication protocol. Additionally, in one embodiment, the preamble 1151 is formatted so that a client station operating in accordance with the HEW protocol can determine that the data unit complies with the HEW communication protocol. For example, at least two OFDM symbols, such as L-SIG (s) 1154 and / or L-LTF2 1156 and / or HEW- The SIGA (s) 1152 are modulated using BPSK modulation. In this case, in one embodiment, the legacy client station will process the data unit 1150 as a legacy data unit, determine the duration of the data unit based on the L-SIG 706, You will refrain from accessing. Further, in one embodiment, one or more other OFDM symbols, e.g., one or more HEW-SIG (s) 1152 of the preamble 1151 are modulated using Q-BPSK modulation and transmitted to a client station Allowing the data unit 1150 to sense whether it 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 a single stream and / or only a single user transmission in the range extension mode. Continuing with FIG. 11B, in one embodiment, where the preamble 1151 includes a HEW-STF 1158 and a HEW-LTF (s) 1160, the AP 14 begins with a HEW- Beam shaping and / or multi-user transmission. In other words, in one embodiment, the fields of the preamble 1151 preceding the HEW-STF 1158 are intended to be received by all intended recipients of the data unit 1150 in an omni-directional, multi-user mode, On the other hand, 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 beamformed and / or other intents of the data unit 1150 Lt; RTI ID = 0.0 > receivers. ≪ / RTI > In one embodiment, the HEW-SIGB field 1162 includes user-specific information for the intended recipients of the data unit 1150 in the MU-MIMO mode. The HEW-SIGB field 1162 is generated using a regular coding scheme or a range extension coding scheme according to an embodiment. Similarly, the HEW-STF 1158 is generated using a regular coding scheme or a range extension coding scheme according to an embodiment. In one embodiment, the training sequence used on the HEW-STF 1158 is a sequence defined in a legacy communication protocol, e.g., the IEEE 802.11ac protocol.

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

In some embodiments, the receiver device uses the HEW-STF field 1158 to resume the automatic gain control (AGC) process to receive the data portion 716. The HEW-STF has the same duration as the VHT-STF (i.e., 4 microseconds) in one embodiment. In other embodiments, the HEW-STF has a longer duration than the VHT-STF. In one embodiment, the HEW-STF has the same time-domain periodicity as the VHT-STF, using the same tone interval as the IEEE 802.11ac in the frequency domain and one non-zero tone every 4 tones. In other embodiments with a 1 / N tone interval, the HEW-STF has one non-zero tone for every 4 * N tones. In embodiments where the overall bandwidth for the data unit is greater than 20 MHz (e.g., 40 MHz, 80 MHz, etc.), the HEW-STF uses the same wide bandwidth VHT-STF as in IEEE 802.11ac Ie 20 MHz VHT-STF redundancy for the entire bandwidth of 40 MHz, 80 MHz, 160 MHz, etc.).

14A is a diagram illustrating a range extended mode data unit 1400 according to one embodiment. The data unit 1400 includes a range extension mode preamble 1401. The extended range mode preamble 1401 is identical to the preamble 1401 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 Lt; RTI ID = 0.0 > 11b < / RTI > 14B is a diagram illustrating an L-Sig field 1406 in accordance with one embodiment. 14B, the L-Sig field 1406 includes a double guard interval 1410, a first L-Sig field 1412 containing the contents of the L-Sig field 706 of the preamble 1151, And a second L-Sig field 1414 containing the contents of the second L-SIG2 field 1154 of the preamble 1151. [ In various embodiments, the L-Sig field 1406 may be set to a fixed value as discussed above for the L-Sig fields 706,1154 of Figure 11B, or a length subfield set to a variable value . In various embodiments, redundant (repeated) bits in the L-Sig field 1406 are used for improved channel estimation as discussed above for the L-Sig fields 706, do.

In one embodiment, the legacy client station receiving the data unit 1400 assumes that the L-Sig field 1406 includes 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 relative to the actual L-Sig field 1412. In one embodiment, to ensure that the constellation points in 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 The modulation of the L-Sig field 1412 is phase-shifted with respect to normal BPSK modulation. For example, in a 20 MHz OFDM symbol, if the normal guard interval is 0.8 占 퐏 and the double guard interval is 1.6 占 퐏, then the modulation of the OFDM tone k of the L-Sig field 1412 will result in the original L- SIG < / RTI > for the corresponding OFDM tone k:

방정식 1

Equation 1

Thus, in one embodiment, the L-Sig field 1412 is modulated using the inverse Q-BPSK instead of the normal BPSK. Thus, in one embodiment, for example, a bit of value 1 is modulated on -j, a bit of value 0 is modulated on j, and a {j, -j} modulation Lt; / RTI > In one embodiment, due to the inverse Q-BPSK modulation of the L-Sig field 1412, the legacy client station in an embodiment may properly decode the L-Sig field 1412 and may be used in the L-SIG 1412 field The duration of the data unit 1400 can be determined. On the other hand, in one embodiment, a client station operating in accordance with the HEW protocol may detect a preamble (e. G., By detecting an iteration of the L-Sig field 1412 or by detecting an inverse Q- 1401) is a range extension mode preamble. Alternatively, in other embodiments, the client station operating in accordance with the HEW protocol may use the other sensing methods discussed above to determine the preamble (s) based on the modulation or format of the HEW-SIGA field (s) 1401) is a range extension mode preamble.

Referring to Figures 11a-11b and 14a, in some embodiments, the long guard interval is set to a normal mode preamble (e.g., preamble 1101 and range extended mode preamble (e.g., preamble 1151 or preamble 1401 LF field 704 and the L-Sig field 702, in one embodiment, are used for the first OFDM symbols of both of the L- 14A, in one embodiment, the L-STF field 702, the L-LTF field 702, and the HEW-SIGA field 1152 are generated using the long guard interval, respectively. 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, (E.g., Q-BPSK) or HEW-SIGA field 1152, in various embodiments the preamble is a normal mode preamble or range Similar to the preamble 1151 of FIG. 11B, the preamble 1401 of FIG. 14A may also be used to determine whether the second L-LTF2 field (1156).

15 is a block diagram illustrating the format of the HEW-SIGA field 1500 according to one embodiment. In some embodiments, the HEW-SIGA field (s) 1152 of the data unit 1150 or the data unit 1400 is formatted into the HEW-SIGA field 1500. In some embodiments, the HEW-SIGA field (s) 1108 is formatted with the HEW-SIGA field 1500. The HEW-SIGA field 1500 includes a double guard interval 1502, a first iteration of the HEW-SIGA field 1504, and a second iteration of the HEW-SIGA field 1506. In an exemplary embodiment, DGI is 1.8 [mu] s and each iteration of HEW-SIGA is 3.2 [mu] s. In one embodiment, the repeated bits in the HEW-SIGA field 1500 are used to increase the reliability of the 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 normal HEW-SIGA field format used in the normal mode, The format of the HEW-SIGA field 1500 is used to auto-sense the range extension mode preamble based on a comparison between the auto-correlation of the HEW-SIGA field of the HEW-SIGA field. In some embodiments, the HEW-SIGA field 1500 provides less redundancy (as compared to the data portion 716) since the additional time domain iteration of the HEW-SIGA field 1500 provides sufficient improvement in decoding performance redundancy.

16 is a block diagram illustrating an example PHY processing unit for generating normal mode data units using a regular coding scheme according to one embodiment. 1, in one embodiment, the AP 14 and the client station 25-1 each include a PHY processing unit, e.g., a PHY processing unit 1600. [ In various embodiments and / or scenarios, the PHY processing unit 1600 generates range extended data units such as, for example, one of the data units of Figures 9a, 9b, 10a, or 10b. PHY processing unit 1600 generally includes a scrambler 1602 that scrambles an information bit stream to reduce the occurrence of long sequences of days or zeros. The FEC encoder 1606 encodes the scrambled information bits to produce encoded data bits. In one embodiment, the FEC encoder 1606 includes a binary convolutional code (BCC) encoder. In another embodiment, the FEC encoder 1606 includes a puncturing block followed by a binary convolutional encoder. In yet other embodiments, the FEC encoder 1606 includes a low density parity check (LDPC) encoder. The interleaver 1610 receives the encoded data bits and interleaves the bits (i.e., changes the order of the bits) to prevent long sequences of adjacent noise bits from entering the decoder at the receiver. Constellation mapper 1614 maps the sequence of interleaved bits to constellation points corresponding to different subcarriers of an OFDM symbol. More specifically, for each spatial stream, constellation mapper 1614 converts the bit sequence of length log ₂ (M) into one of the M constellation points.

The output of constellation mapper 1614 is operated by an inverse discrete Fourier transform (IDFT) unit 1618 that transforms blocks of constellation points into time-domain signals. In embodiments or situations where the PHY processing unit 1600 operates to generate data units for transmission over multiple spatial streams, the cyclic shift diversity (CSD) unit 1622 is intentional To prevent non-beamforming, a cyclic shift is inserted into all but one of the spatial streams. The output of the CSD unit 1622 is used to smooth the edges of each symbol to increase the decay of the spectrum for the OFDM symbol and to adjust the guard interval < RTI ID = 0.0 > (GI) insertion and window unit 1626. The output of the GI insertion and window unit 1626 is provided to an analog and radio frequency (RF) unit 1630 which converts the signal to an analog signal for transmission and upconverts the signal to an RF frequency.

In various embodiments, the range extension mode corresponds to the lowest data rate modulation and coding scheme (MCS) of the normal mode, and redundancy or repetition of bits may be applied to at least some of the fields or symbols of the data unit . For example, in various embodiments and / or scenarios, the range extension mode may be implemented in accordance with one or more range extension coding schemes described below in the data portion of the extended mode extended data unit and / or the non- It is introduced by repetition of symbols. As an example, according to one embodiment, normal mode data units are generated according to a regular coding scheme. In various embodiments, the regular coding scheme may use a set of MCSs, such as MCS0 (BPSK modulation and 1/2 coding rate) to MCS9 (Quadrature Amplitude Modulation (QAM) and 5/6 coding rate ) And the higher order MCSs correspond to the higher data rates. In one such embodiment, the range extended mode data units are generated using a range extension coding technique such as additional bit repetition, block encoding, or symbol repetition that further reduces the data rate and modulation and coding defined by MCSO do.

17A is a block diagram illustrating an example PHY processing unit 1700 for generating range extended mode data units using a range extension coding technique in accordance with one embodiment. In some embodiments, the PHY processing unit 1700 generates data fields and / or signals of the extended mode data units. With reference to Figure 1, in one embodiment, the AP 14 and the client station 25-1 each include a PHY processing unit, e.g., a PHY processing unit 1700.

The PHY processing unit 1700 is similar to the PHY processing unit 1600 of Figure 16 except that the PHY processing unit 1700 includes a block coder 1704 coupled to the scrambler 1702. In one embodiment, the block coder 1704 reads the incoming (scrambled) information bits of one block at a time, generates many copies of each block (or each bit in the block), and, in accordance with the range extension coding technique Interleaves the resulting bits and outputs interleaved bits for further encoding by FEC encoder 1706 (e.g., a binary convolutional encoder). In general, each block, according to one embodiment, receives a plurality of information bits that fill the data tones of a single OFDM symbol, after being encoded by the block coder 1704 and by the FEC encoder 1706. As an example, in one embodiment, the block coder 1704 generates two copies (2x iterations) of each block of 12 information bits to produce the 24 bits contained in the OFDM symbol. The 24 bits are then encoded by the FEC encoder 1706 at a coding rate of 1/2 to produce the 48 bits that have modulated 48 data tones of the OFDM symbol (e.g., using BPSK modulation). As another example, in another embodiment, block coder 1704 generates 24 bits encoded by FEC encoder 1706 at a coding rate of 1/2 to produce 48 bits that modulate 48 data tones of an OFDM symbol (4x iterations) of each block of 6 information bits in order to do so. As another example, in another embodiment, the block coder 1704 may include 26 bits encoded by the FEC encoder 1706 at a coding rate of 1/2 to generate 52 bits that modulate 52 data tones of an OFDM symbol To generate two copies (2x repeats) of each block of 13 information bits to generate. 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 in an OFDM symbol.

In some embodiments, the block coder 1704 generates a data (or signal) field as defined by the MCS0 specified in the IEEE 802.11n standard for the 20 MHz channel, i.e., 52 data tones per OFDM symbol Apply the 4x iteration technique. In this case, according to one embodiment, the block coder 1704 generates four copies of each block of 6 information bits to generate 24 bits, and then generates two copies of the padding bits (i. E. A number of bits designated 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) (I.e., 26 bits for 52 data tones).

In one embodiment, block coder 1704 uses a "block level" iteration scheme where each block of n bits is repeated m consecutive times. As an example, according to one embodiment, if m is equal to 4 (4x iterations), block coder 1704 generates sequences [C, C, C, C] and C is a block of n bits. In another embodiment, block coder 1704 uses a "bit level" iteration scheme where each incoming bit is repeated m consecutive times. In this case, in one embodiment, if m equals 4 (4x iterations), the block coder 1704 generates a sequence [b1 b1 b1 b1 b2 b2 b2 b2 b3 b3 b3 b3. . . B1 is the first bit in the block of bits, b2 is the second bit, and so on. In yet other embodiments, block coder 1704 generates m 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 include any suitable code, for example a Hamming block code with a coding rate of 1/2, 1/4, (1, 2) or (1, 4) block code, (12,24) block code or (6, 24) block code having a coding rate of 1/4, (13,26) block codes, etc.) to encode incoming blocks of incoming bits or bits.

According to one embodiment, the effective coding rate corresponding to the combination of coding performed by coding block coder 1704 and coding performed by FEC encoder 1706 is the product of the two coding rates. For example, in one embodiment where the block coder 1704 uses a 4x iteration (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 / 8. In accordance with one embodiment, as a result of the reduced coding rate compared to the coding rate used to generate the similar normal mode data unit, the data rate in the range extended mode is a factor corresponding to the coding rate provided to the block coder 1704 (For example, a factor of two, a factor of four, etc.).

In accordance with some embodiments, the block coder 1704 uses the same block coding scheme as the block coding scheme used to generate the data portion of the control mode data unit to generate the signal field of the control mode data unit. For example, in one embodiment, the OFDM symbols of the signal field and the OFDM symbols of the data portion, each including 48 data tones, in this embodiment, for example, a block coder 1704, A 2x iteration scheme is applied to the blocks of 12 bits. In another embodiment, the data and signal fields 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 as compared to the number of data tones per OFDM symbol in the data portion. Thus, in this embodiment, when operating on a signal field as compared to the block size and coding scheme used to generate the data portion, the block coder 1704 may use different block sizes and, in some embodiments, Lt; / RTI > For example, if a long-range communication protocol specifies 52 data tones per OFDM symbol in the signal field and 48 data tones per OFDM tones in the data portion, then block coder 1704, according to one embodiment, To the blocks of 13 bits of the data portion and to the blocks of 12 bits of the data portion.

An FEC encoder 1706 according to one embodiment encodes the block coded information bits. In one embodiment, BCC encoding is performed continuously over the entire field being created (e.g., 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 designated size (e.g., 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 continuously encodes the incoming bits.

Similar to the interleaver 1610 of FIG. 16, in various embodiments, an interleaver 1710 may vary the order of the bits to provide diversity gain, Reduces the likelihood of collapsing on a 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 extended mode data unit are padded so that the data unit occupies, for example, an integer number of OFDM symbols (i.e., many bits of the known value are padded to information bits . 1, padding is implemented in the MAC processing units 18, 28 and / or PHY processing units 20, 29 in some embodiments. In some such embodiments, the number of padding bits is determined according to padding equations provided in a short range communication protocol (e.g., IEEE 802.11a standard, IEEE 802.11n standard, IEEE 802.11ac standard, etc.). In general, these padding equations include calculating a number of padding bits based on a number of data bits (N _DBPS ) per OFDM symbol and / or a number of coded data bits (N _CBPS ) per symbol It is accompanied. In a range extended mode, according to one embodiment, the number of padding bits is based on the number of information bits in the OFDM symbol before the information bits are block encoded by the block coder 1704 and BCC encoded by the FEC encoder 1706. [ (E.g., 6 bits, 12 bits, 13 bits, etc.). Thus, the number of padding bits in a range extended mode data unit is generally determined to be within the corresponding normal mode data (or corresponding short range data Unit) padding bits. On the other hand, according to one embodiment, the number of coded bits per symbol is the number of coded bits per symbol in the normal mode data unit (or in the corresponding short range data unit), e.g., the number of coded bits per OFDM 24, 48, 52, and so on.

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

The PHY processing unit 1750 is similar to the PHY processing unit 1700 of Figure 17A except that the FEC encoder 1706 in the PHY processing unit 1750 has been replaced by an LDPC encoder 1756. [ Thus, in this embodiment, the output of the block coder 1704 is provided for additional 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 the adjacent 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 one embodiment, an LDPC tone remapping unit 1760 reorders blocks of coded information bits or coded information bits according to a tone remapping function. Mapping the successive coded information bits or blocks of information bits in the cases where successive OFDM tones are adversely affecting during transmission to map on non-contiguous tones in the OFDM symbol to enable data recovery at the receiver a tone remapping function is generally defined. In some embodiments, the LDPC tone remapping unit 1760 is omitted. 17A, many tail bits are typically added to each field of the data unit for proper operation of the FEC encoder 1706, for example, to encode each of the encoded < RTI ID = 0.0 > After the field is encoded, it ensures that the BCC encoder goes back to the zero state. In one embodiment, for example, six tail bits may be inserted at the end of the data portion before the data portion is provided to the FEC encoder 1706 (e.g., after the bits are processed by the block coder 1704) do.

In some embodiments, the signal field of the extended mode data unit has a different format as compared to the signal field format of the normal mode data unit. In some such embodiments, the signal field of the extended mode data units is shorter compared to the signal field format of the normal mode data unit. For example, according to one embodiment, only one modulation and coding scheme is used in the range extension mode so that information (or some information) about modulation and coding need not be communicated in the range extension mode signal field. Similarly, in one embodiment, the maximum length of the extended mode data unit is shorter by comparing the maximum length of the normal mode data unit, and in this case, few bits are required for the length subfield of the extended 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 may include some subfields (e.g., a low density parity check (LDPC) subfield, space time block coding (STBC) Fields, etc.) are omitted. Additionally or alternatively, in some embodiments, the Range Expansion Mode signal field includes a shorter CRC subfield compared to the cyclic redundancy check (CRC) subfield of the normal mode signal field (e.g., 8 bits Small). In general, in some embodiments, in the extended range mode, 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 extended mode data units using a range extension coding technique in accordance with another embodiment. In some embodiments, the PHY processing unit 1800 generates data fields and / or signals of the extended mode data units. 1, in one embodiment, the AP 14 and the client station 25-1 each include a PHY processing unit, e.g., a PHY processing unit 1800. [

The PHY processing unit 1800 is similar to the PHY processing unit 1700 of Figure 17A except that the block coder 1808 is located behind the FEC encoder 1806 in the PHY processing unit 1800. [ Thus, in this embodiment, the information bits are first scrambled by the scrambler 1802, the FEC encoded 1806 encoded bits are then replicated or otherwise decoded by the block coder 1808, Lt; / RTI > In an exemplary 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 (e.g., the entire data portion, , 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 designated 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 1/2 coding rate to generate 24 BCC coded bits and outputs the BCC coded bits to a block coder 1808). In one embodiment, the block coder 1808 generates two copies of each incoming block and interleaves the generated bits according to the Range Extended Coding Scheme coding technique to generate the 48 bits to be included in the OFDM symbol. In one such embodiment, the 48 bits correspond to 48 data tones generated using Fast Fourier Transform (FFT) of size 64 in the IDFT processing unit 1818. As another example, in another embodiment, the FEC encoder 1806 may encode 6 information bits per OFDM symbol using a 1/2 coding rate to generate 12 BCC coded bits, and transmit the BCC coded bits to a block coder 1808). In one embodiment, the block coder 1808 generates two copies of each incoming block and interleaves the generated bits according to a range extension coding scheme 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 Fast Fourier Transform (FFT) of size 32 in the IDFT processing unit 1818.

Similar to the block coder 1704 of FIG. 17A, the range extension coding scheme used by the block coder 1808 to generate the signal field of the range extended mode data unit according to the embodiment is the data portion of the range extended mode data unit Lt; RTI ID = 0.0 > 1808 < / RTI > In various embodiments, block coder 1808 may be implemented as a "block level" iteration scheme or a "bit level" iteration scheme as discussed above in connection with block coder 1704 of FIG. Lt; / RTI > Similarly, in other embodiments, the block coder 1808 may generate copies of m number of incoming bits and interleave the resulting bit stream according to the appropriate code, or otherwise, (1, 2) or (1, 2, 3, 4) having a coding rate of 1/2, 1/4, 4) block codes, (12,24) block codes or (6,24) block codes, (13,26) block codes, etc.). According to one embodiment, the effective coding rate for the data units generated by the PHY processing unit 1800 is determined by the coding rate used by the FEC encoder 1806 and the repetition used by the block coder 1808. [ (Or coding rate).

In one embodiment, the block coder 1808 provides sufficient diversity gain so that no further interleaving of the coded bits is required, and the interleaver 1810 is omitted. One advantage of omitting the interleaver 1810 is that in this case the OFDM symbols with 52 data tones may be generated using 4x or 6x iterative techniques even if the number of data bits per symbol in some of these situations is not an integer . For example, in one such embodiment, the output of the FEC encoder 1806 is divided into blocks of 13 bits and each block may be divided into four (or a quarter of the rate) to produce 52 bits to be included in the OFDM symbol Block encoded). In this case, if the FEC encoder 1806 uses a coding rate of 1/2, the number of data bits per symbol is equal to 6.5. In an exemplary embodiment using 6x iterations, the FEC encoder 1806 encodes the information bits using a coding rate of 1/2 and the output is divided into blocks of four bits. The block coder 1808 repeats each of the four bit blocks six times (or block encodes each block using a 1/6 coding rate) and generates four padding bits < RTI ID = 0.0 > (padding bits).

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

Also, in the example of the PHY processing unit 1700 of Figure 17, many tail bits are typically inserted into each field of the data unit for proper operation of the FEC encoder 1806, for example, After the field of the BCC encoder is encoded, the BCC encoder goes back to the zero state. In one embodiment, six tail bits are inserted at the end of the data portion, for example, before the data portion is provided to the FEC encoder 1806 (e.g., 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 in which the block coder 1808 uses a 4x iteration technique (or other block code with a coding rate of 1/4), the FEC encoder 1806 uses a coding rate of 1/2, (Including tail bits), and the 24 signal field bits are BCC encoded to produce 48 BCC encoded bits, and then encoded for each of the 12 bits < RTI ID = 0.0 > 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 six information bits of the signal field.

Furthermore, in some embodiments, the PHY processing unit 1800 generates OFDM symbols with 52 data tones in accordance with the MCS0 specified in the IEEE 802.11n standard or the IEEE 802.11ac standard, and the block coder 1808 uses the 4x iteration technique do. In some such embodiments, excess padding is used to ensure that the resulting encoded data stream to be included in an OFDM symbol contains 52 bits. In one such embodiment, the padding bits are added to the coded information bits after the bits are 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, the PAPR reduction unit 1809 flips the bits in some or all of the repeated blocks to reduce or eliminate the occurrence of the same bit sequences at different frequency positions in the OFDM symbol, To-peak power ratio. Generally, the bit flip includes changing the bit value zero to bit value day and changing the bit value day to bit value zero. According to one embodiment, the PAPR reduction unit 1809 implements bit flipping using XOR operation. For example, in one embodiment using a 4x iteration of a block of coded bits, if a block of coded bits to be included in the OFDM symbols is denoted C and if C '= C XOR 1 (i.e., , Then some possible bit sequences at the output of the 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 un-flipped bits may 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 extended mode data units according to another embodiment. In some embodiments, the PHY processing unit 1850 generates data fields and / or signals of the extended mode data units. 1, in one embodiment, the AP 14 and the client station 25-1 each include a PHY processing unit, e.g., a PHY processing unit 1850. [

The PHY processing unit 1850 is similar to the PHY processing unit 1800 of Figure 18 except that the FEC encoder 1806 in the PHY processing unit 1850 has been replaced by an 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 duplicated 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 adjacent 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 one embodiment, the LDPC tone remapping unit 1860 rearranges the blocks of coded information bits or coded information bits according to the tone remapping function. Mapping the successive coded information bits or blocks of information bits in the cases where successive OFDM tones are adversely affecting during transmission to map on non-contiguous tones in the OFDM symbol to enable data recovery at the receiver Is defined in its entirety. 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 extended mode data units according to another embodiment. In some embodiments, PHY processing unit 1900 generates data fields and / or signals of range extended mode data units. 1, in one embodiment, the AP 14 and the client station 25-1 each include a PHY processing unit, e.g., a PHY processing unit 1900.

The PHY processing unit 1900 is similar to the PHY processing unit 1800 of FIG. 18A except that a block coder 1916 is located behind the constellation mapper 1914 in the PHY processing unit 1900. Thus, in this embodiment, the BCC encoded information bits after being processed by interleaver 1910 are mapped to constellation symbols and then constellation symbols are duplicated or otherwise decoded by block coder 1916 do. According to one embodiment, processing by the FEC encoder 1906 is performed continuously over the entire field being created (e.g., 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 constellation symbols by the constellation mapper 1914. The constellation symbols are then partitioned into blocks of a designated size (e.g., six symbols, twelve symbols, thirteen symbols, or any other suitable number of symbols), and then each block is partitioned into a block coder (1916). As an example, in one embodiment using 2x iterations, constellation mapper 1914 generates 24 constellation symbols and block coder 1916 generates 48 constellation symbols corresponding to 48 data tones of the OFDM symbol ( For example, two copies of 24 symbols (as specified in the IEEE 802.11a standard). As another example, in one embodiment using 4x iteration, constellation mapper 1914 generates 12 constellation symbols and block coder 1916 generates 48 symbols corresponding to 48 data tones of the OFDM symbol ( (E.g., as specified in the IEEE 802.11a standard). As another example, in one embodiment using 2x iterations, constellation mapper 1914 generates 26 constellation symbols and block coder 1916 generates 52 constellations corresponding to 52 data tones of the OFDM symbol (E. G., Generates two copies of 26 symbols) as indicated in the IEEE 802.11n standard or the IEEE 802.11ac standard. Generally, in various embodiments and / or scenarios, block coder 1916 generates any suitable number of copies of the blocks of incoming awareness symbols and interleaves the generated symbols according to any appropriate coding scheme. Similar to the block coder 1704 of FIG. 17A and the block coder 1808 of FIG. 18A, a block coder 1916 is used to generate a signal field (or signal fields) of a range extended mode data unit, 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 extended mode data unit. According to one embodiment, the effective coding rate for the data units generated by the PHY processing unit 1900 depends on the coding rate used by the FEC encoder 1906 and the number of iterations used by the block coder 1916 Coding rate).

In accordance with one embodiment, since the redundancy is introduced after the information bits are mapped to constellation symbols in this case, each OFDM symbol generated by the PHY processing unit 1900 is subjected to OFDM And includes less non-overlapping data tones as compared to data tones. Thus, the interleaver 1910 operates on fewer tones per OFDM symbol as compared to the interleaver used in the normal mode (e.g., the interleaver 1610 of FIG. 16) or the interleaver used when generating the corresponding short range data unit . For example, in one embodiment with 12 non-redundant data tones per OFDM symbol, the interleaver 1910 may determine the number of columns (N _col ) 6 and the number of _rows (N _row ) 2 * the number of bits per subcarrier N _bpscs ). In another exemplary 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, interleaver parameters other than the interleaver parameters used in the normal mode are used for the interleaver 1910. Alternatively, in one embodiment, the block coder 1916 provides sufficient diversity gain so that no additional interleaving of the coded bits is required, and the interleaver 1910 is omitted. In this case, as in the exemplary embodiment using the PHY processing unit 1800 of FIG. 18A, the OFDM symbols with 52 data tones may be used even if the number of data bits per symbol in some of these situations is not a 4x or 6x iteration scheme Lt; / RTI >

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

In some embodiments, the PHY processing unit 1900 generates OFDM symbols with 52 data tones in accordance with the MCS0 specified in the IEEE 802.11n standard or the IEEE 802.11ac standard, and the block coder 1916 uses the 4x iteration scheme. In some such embodiments, excess padding is used to ensure that the resulting encoded data stream to be included in an OFDM symbol contains 52 bits. In one such embodiment, the padding bits are added to the coded information bits after the bits are 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 a portion of the data tones that are repeatedly modulated. For example, in one embodiment the added phase shift is 180 degrees. The 180 degree phase shift corresponds to the sign flip of the bits that modulate the data tones in which the phase shifts are implemented. In another embodiment, the PAPR reduction unit 1917 adds 180 degrees of phase shift (e.g., 90 degrees phase shift or any other suitable phase shift). As an example, in one embodiment using 4x iteration, if a block of 12 constellation symbols to be included in the OFDM symbols is denoted as C and a simple block iteration is performed, the resulting sequence is [C C C C]. In some embodiments, the PAPR reduction unit 1917 introduces a 90 degree phase shift (i.e., j * C) for the code flip (i.e., -C) or for some repeated blocks. In some such embodiments, the resulting sequence may be, for example, [C 1 -C 6 -C 6], [-C 2 -C 6 -C 6], [C 6 -C 6] J * C, j * C, j * C], or any other combination of C, -C, j * C, and -j * C. In general, any suitable phase shift in various embodiments and / or scenarios may be introduced into any repeated block. In some embodiments, the PAPR reduction unit 1809 is omitted.

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

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

The PHY processing unit 1950 is similar to the PHY processing unit 1900 of Figure 19 except that the FEC encoder 1906 in the PHY processing unit 1950 is replaced by an LDPC encoder 1956. [ Thus, in this embodiment, LDPC encoded information bits are mapped to constellation symbols by constellation mapper 1914 and then constellation symbols are duplicated or otherwise block encoded by 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, according to one embodiment, the PHY processing unit 1950 omits the interleaver 1910 because adjacent 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 1960. According to one embodiment, the LDPC tone remapping unit 1960 rearranges blocks of coded information bits or coded information bits according to the tone remapping function. Mapping the successive coded information bits or blocks of information bits in the cases where successive OFDM tones are adversely affecting during transmission to map on non-contiguous tones in the OFDM symbol to enable data recovery at the receiver Is defined in its entirety. In some embodiments, the LDPC tone remapping unit 1960 is omitted.

In the embodiments described above with respect to FIGS. 17-19, the range extension mode introduces redundancy by repeating constellation symbols in the bits and / or frequency domain. Alternatively, in some embodiments, the range extension coding scheme includes OFDM symbol repetition of the data fields and / or signals of the extended mode data units performed in the time domain. For example, FIG. 20A is a diagram illustrating a 2x iteration of each OFDM symbol of the HT-SIG1 and HT-SIG2 fields in the preamble of a range extended mode data unit according to one embodiment. Similarly, FIG. 20B is a diagram showing a 2x iteration of each OFDM symbol in the L-Sig field in the preamble of the extended mode data unit according to one embodiment. 20C is a diagram illustrating a time domain repetition technique for OFDM symbols in a 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, the OFDM symbol repeats are output in succession in the embodiment of FIG. 20C, but the OFDM symbol repeats in the embodiment of FIG. 20D are interleaved. In general, OFDM symbol repeats 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 Figure 1, a method 2100 is implemented by the network interface 16, in one embodiment. For example, in one such embodiment, the PHY processing unit 20 is configured to implement the method 2100. According to yet another embodiment, the MAC processing 18 is also configured to implement in at least a portion of the method 2100. Still referring to FIG. 1, in another embodiment, the method 2100 is implemented by a network interface 27 (e.g., PHY processing unit 29 and / or MAC processing unit 28). In other embodiments, the 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 repeat technique described above for the block coder 1704 of FIG. At block 2104, the information bits are encoded using an FEC encoder, such as 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 containing OFDM symbols is generated.

In one embodiment, as illustrated in FIG. 21, for example, as described above with respect to FIG. 17A, the information bits are first encoded using a block encoder (block 2102) and the block coded bits are then encoded using the FEC encoder The order of the blocks 2102 and 2104 is interchanged. In this embodiment, for example, as shown in Figure 18A, The information bits are first FEC encoded and the FEC encoded bits are encoded according to the block coding technique. In still other embodiments, block 2102 is located after block 2106. In this embodiment, The FEC encoded bits in block 2104 are mapped to constellation symbols in block 2106 and then the constellation symbols are passed to block 2102 as described above with respect to Figure 19A, Lt; / RTI > is encoded according to a block coding or iterative technique.

In various embodiments, the range extension coding scheme employs a reduced-size fast Fourier transform (FFT) technique that outputs a reduced number of constellation symbols that are repeated over the entire lane width 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 (e.g., a 32-FFT mode) having 24 data tones. The 32 subcarriers correspond to the 10 MHz subband 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 replication 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 over each 10 MHz subband of the total 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, a plurality of constellations are repeated 4x over the entire 20 MHz bandwidth (i.e., in each 5 MHz subband). Thus, the receiving device combines multiple constellations to improve the decoding reliability of constellation. In some embodiments, the modulation of the different 5 or 10 MHz sub-bandwidth signals is rotated by different angles. For example, in one embodiment, the first sub-band is rotated 0-, the second sub-band is rotated 90- degrees, the third sub-band is rotated 180- -. In other embodiments, different suitable rotations are used. The different phases of the 20 MHz sub-band signals result, in at least some embodiments, to a reduced peak-to-average power ratio (PAPR) of the OFDM symbols in the data unit.

22A is a diagram of a 20 MHz full bandwidth with 2x iterations having a range extended data unit with a 10 MHz subband according to one embodiment. As shown in Fig. 22A, each subband of 10 MHz is rotated by rotation r1 and r2 individually. 22B is a diagram of a 40 MHz full bandwidth with 4x iterations of a range extended data unit having a 10 MHz subband in accordance with one embodiment. As shown in Fig. 22B, each subband of 10 MHz is rotated by rotation r1, r2, r3, and r4 individually. 22C is a diagram of an example tone plan 2230 for a 32-FFT mode corresponding to a 10 MHz subband in accordance with one embodiment. Tone plan 2230 includes 32 total tones with 24 data tones, 2 pilot tones at indices +7 and -7, 1 DC current tone, and 5 guard tones as shown in FIG. In embodiments where a reduced size FFT technique is used, the corresponding tone plan is used for the HEW-LTF field if present. In other embodiments where a reduced size FFT technique is used but no HEW-LTF field is present, the L-LTF field 704 includes an additional < RTI ID = 0.0 > ± 1 < / RTI > code for pilot tones for corresponding indices of the modified tone plan . For example, in one embodiment, tones -29, -27, +27, and +29 are added to the tone plan for the L-LTF field. In a further embodiment, the ± 1 codes are removed from the L-LTF tone plan at tones -2, -1, 1, and 2 within the 20 MHz bandwidth. Similar changes are applied for the entire bandwidths of 40 MHz, 80 MHz, 160 MHz, and so on.

23 is a diagram of an example data unit 2300 in which a laser enhancement mode according to one embodiment is used for a preamble 2301 of a data unit. In some embodiments, preamble 2301 indicates both normal mode and range extended mode. In this embodiment, other methods are used to distinguish between the extended mode and the normal mode, such as those described above with respect to Figures 9, 10, and 11.

The data unit 2301 is generally similar to the data unit 1150 of Figure 11B except that the preamble 2301 of the data unit 2300 is formatted differently from the preamble 1151 of the data unit 1101, ≪ / RTI > In one embodiment, the preamble 2301 is formatted such that the receiving device operating in accordance with the HEW communication protocol can determine that the preamble 2301 is a range extension mode preamble instead of the regular mode preamble. In one embodiment, preamble 2301 includes a modified long training field M-LTF 2304 and a modified long training field M-LTF 2304, instead of L-LTF 704 and L-SIG 706, Signal field M-SIG (2306). In one embodiment, the preamble 2301 includes an L-STF 702, a double guard interval followed by two iterations of the modified long training sequence as M-LTF 2304, a normal guard interval, and a modified signal field M -SIG. In some embodiments, the preamble 2301 further includes one or more first HEW signal fields (HEW-SIGAs) In one embodiment, the preamble 2301 further comprises 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) In other embodiments, preamble 2301 omits L-SIG (s) 1154 and / or 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, preamble 2301 omits HEW-STF 1158, HEW-LTF (s) 1160 and / or HEW-SIGB 1162. In one embodiment, the data unit 2300 also includes a data portion 716 (not shown in Fig. 23). In some embodiments, the HEW signal fields (HEW-SIGAs) 1152 are modulated using the same range extension coding scheme as the data field 716.

In various embodiments, M-LTF 2304 corresponds to L-LTF 704 multiplied by a predetermined sequence (e.g., 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) For example, ± 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 of the predetermined sequence (i. E., Many values) is equal to the sum of many data tones and many pilot tones per 20 MHz band in the IEEE 802.11ac protocol, e.g., 52 values And 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. If the HEW-STF and / or HEW-LTF fields are not present in the range extension preamble, as described above with respect to the tone plan 2230 for the 32-FFT mode corresponding to the 10 MHz subband, Lt; RTI ID = 0.0 > L-LTF < / RTI > In one embodiment, the tone plan is inconsistent between 20 MHz L-LTF and the 10 MHz 32-FFT mode is used for missing tones (e.g., for tones -29, -27, +27, 29) by inserting +1 or -1 codes into the L-LTF.

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

The PHY processing unit 2400 is similar to the PHY processing unit 1700 of Figure 17A except that a tone multiplier 2404 is located behind the constellation mapper 1614 in the PHY processing unit 2400. [ (I. E., M-SIG 2306) for the L-Sig field and ii) the L-LTF field of the range extension mode data unit I. E., M-LTF 2304).

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

In one embodiment, tone multiplier 2404 receives constellation symbols for data contained in L-SIG 706 from constellation mapper 1614 and generates constellation symbols for pilot tones from pilot tone generator 2408 Lt; / RTI > Thus, in one embodiment, the M-SIG 2306 output from tone multiplier 2404 includes modified constellation symbols for data tones and pilot tones that are to be transformed into time-domain signals by IDFT 1618. [

In some embodiments, the receiver device decodes M-SIG 2306 using channel estimates based on, for example, M-LTF 2304. In this example, since both L-LTF 704 and L-SIG 706 are multiplied by a predetermined sequence, the legacy receiver device may perform multiplication as part of the channel estimation process or autocorrelation process Efficiently. In one embodiment, the receiving device determines that the preamble does not multiply the LTF field (e.g., M-LTF 2304 or L-LTF 704) in the preamble with a predetermined sequence and multiplies the pre- (E. G., Multiplied) and not multiplying with a predetermined sequence based on the auto-correlation of the field to the range extension mode preamble 2400 or to the normal mode preamble 1101 Or not. In one embodiment, the receiving device performs a first auto-correlation of LTFs with L-LTF 704, a second auto-correlation of LTFs with M-LTF 2304, Perform a comparison of the results. In one embodiment, if the autocorrelation to M-LTF 2304 produces a larger result compared to the result of the autocorrelation to L-LTF 704, then the receiving device may determine that the preamble is an extended mode preamble (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, Mode normal preamble 1101 corresponds to the normal 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 range extension mode or L-LTF _i for normal 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 channel estimation from the M-LTF to decode additional fields of the data unit (i.e., HEW-SIG and / or data fields). In some scenarios, the values of the predetermined sequence corresponding to the pilot tones are all equal and allow phase tracking on the pilot tones.

In some embodiments, OFDM modulation with reduced tone intervals is used with the same size FFT to reduce the data rate in the range extension mode. For example, the normal 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 extended mode uses 2 OFDM data tones resulting in 128 OFDM tones in the same bandwidth Use a tone interval that is reduced by a factor. In this case, the tone intervals in the range extended mode OFDM symbols are reduced by a factor of 2 compared to the normal 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 normal 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 extended mode uses 20 MHz OFDM A tone interval reduced by 1/4 is used for the data unit. In this case, the tone interval in the range extended mode OFDM symbols is reduced by a factor of 4 compared to the normal mode OFDM symbols (1/4) while using a 4x increased symbol duration and a 4x increased guard interval. In these embodiments, for example, a long GI duration of 1.6 mu s is used. However, in one embodiment, the duration of the information portion of the extended-mode OFDM symbol is increased (e.g., from 3.2 μs to 6.4 μs), and the percentage of total OFDM symbol durations versus GI fraction durations remains the same do. Thus, in this case, efficiency loss is avoided due to the longer GI symbols in at least some embodiments. In various embodiments, the term " long guard interval " used in the present application 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 interval is reduced, the guard intervals are increased, and the symbol duration is increased according to factors 6, 8, or other appropriate values. In some embodiments, variations in tone spacing, guard intervals, and symbol duration are used in combination with block coding or symbol repetition as described above.

The charge-up bandwidth of the data units for the range extension mode is 20 MHz in some embodiments. For example, the increased signal bandwidth will not further increase the range or improve the 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-interval is reduced by a factor of four for the range extension mode, then the overall bandwidth for the 512 FFT is 40 MHz and therefore 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 (e.g., 160 MHz). In various embodiments, for example, the ½ tone interval may be 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, Lt; RTI ID = 0.0 > 1024 < / RTI > In some embodiments, the reduced tone interval is used in combination with a smaller FFT size. In various embodiments, shorter guard intervals may be used, 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 is a reduction of 1 / 9th of the OFDM symbol Lt; / RTI > tone interval.

In some embodiments, the range extension mode uses a smaller tone interval (i.e., ½, ¼, etc.). In this embodiment, the same FFT size, for example, represents a smaller bandwidth corresponding to 64 FFTs for the 10 MHz band for a half tone interval. In one embodiment, the tone plan in the same FFT size is the same for both the extended and normal modes. For example, in a range extended mode, a 64 FFT is equivalent to a 64 FFT for 20 MHz in IEEE 802.11ac, (tone plan) is used. 25A is a diagram of an exemplary 20 MHz full bandwidth with ½ tone spacing in accordance with one embodiment. In this case, the indices for the original DC tones of the legacy tone plan for each 64 FFT are now in the middle of the 10 MHz subband instead of the middle of the total 20 MHz bandwidth, and the indices for the original guard tones are real DC tone . In some embodiments where the band used for the range extended mode data unit is less than 20 MHz, since the indices will not overlap with the " true DC tone ", the smallest signal bandwidth is either the range extended mode or the regular Mode, the non-legacy tone plan includes additional data or pilot tones in the indices for 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 interval is reduced, the influence from the DC current offset and the carrier frequency offset (CFO) becomes larger as compared to the normal mode. 25B is a diagram of an exemplary 20 MHz full bandwidth with ½ tone spacing, in accordance with one embodiment. In some embodiments, the additional zero tones are defined to be close to the DC current tones of the band for the non-legacy tone plan of the range extension mode as compared to the legacy tone plan of the same FFT size in normal mode. In various embodiments, for example, when the FFT size is greater than or equal to 128 with a tone spacing reduced by ½, or when the FFT size is greater than or equal to 256 with a tone spacing reduced by ¼, Additional zero tones are defined above the determined FFT size and / or tone spacing. In some embodiments, an increased number of guard tones, for example, to maintain the same absolute guard interval (e.g., absolute frequency spacing) at band edges as compared to a legacy tone plan in normal mode, Legacy tone plan for the non-legacy tone plan. 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 instances, the same absolute guard spacing facilitates filter designs. In some embodiments, for example, if the total number of data tones for a non-legacy tone plan differs from the same FFT size in normal mode, the PHY parameters for the FEC interleaver and / or the LDPC tone mapper may be non- Is redefined for the number of data tones in the plan.

Figure 26A is a diagram of a non-legacy tone plan 2600 for a range extended mode having a size 64 FFT and a ½ tone spacing in accordance with one embodiment. In the non-legacy tone plan 2600, additional guard tones are included (i.e., guard tones -28, -27, +27, +28) as compared to the legacy tone plan for the normal mode. In some embodiments, 64 FFTs are clustered into a DC tone with pilot tones or data tones. FIG. 26B is a diagram of a non-legacy tone plan 2601 for a range extended mode having a size 128 FFT and a 1/2 tone spacing according to one embodiment. In the non-legacy tone plan 2601, additional guard tones (i.e., guard tones -58, -57, +57, +58) and additional DC tones (i.e., DC Tones -2, -1, 0, 1, 2). Figure 26C is a diagram of a non-legacy tone plan 2602 for a range extension mode with a size 256 FFT and a ½ tone spacing, according to one embodiment. In the non-legacy tone plan 2602, additional guard tones (i.e., guard tones -122, -121, +121, +122) and additional DC tones (i.e., DC Tones -2, -1, 0, 1, 2). 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 normal mode.

FIG. 27 is a flow diagram of an exemplary method 2700 for generating a data unit according to an embodiment. Referring to Figure 1, a method 2700 is implemented by the 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 yet another embodiment, the MAC processing 18 is also configured to implement in at least a portion of the method 2700. [ Still referring to FIG. 1, in another embodiment, the method 2700 is implemented by a network interface 27 (e.g., PHY processing unit 29 and / or MAC processing unit 28). In other embodiments, the 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 in block 2702 may include generating a OFDM symbol of the data portion according to one of a range extension coding technique corresponding to the range extension mode or a regular coding technique corresponding to the normal mode . In one embodiment, the range extension coding scheme includes the range extension coding techniques described above with respect to FIG. 10 (e.g., reduced tone spacing). In another embodiment, the range extension coding scheme includes the range extension coding techniques (e.g., bit-wise iteration or symbol repetition) described above with respect to Figures 17-20. In another embodiment, the range extension coding scheme includes the range extension coding techniques (e. G., Data unit repetition) described above with respect to FIG. In another embodiment, the range extension coding scheme includes an appropriate combination of the range extension coding schemes described above with respect to Figures 10, 17-20, and 22.

In one embodiment, generating OFDM symbols for a data portion of a PHY data unit in accordance with a range extension coding scheme includes: generating a forward error correction (FEC) encoder (e.g., a FEC encoder (1706), (1806), or (1906)) to encode a plurality of information bits; For example, using the constellation mapper 1614 or 1914, mapping the plurality of encoded bits to a plurality of constellation symbols; For example, generating the OFDM symbols including the plurality of constellation symbols using IDFT 1618 or 1818. In one embodiment, generating OFDM symbols comprises the steps of: i) encoding a plurality of information bits according to a block coding technique (e.g., using a block coder 1704); ii) according to a block coding technique (E.g., using a block coder 1808), or iii) encoding a plurality of constellation symbols in accordance with an encoding block coding scheme (e.g., using a block coder 1916). ≪ / RTI > In another embodiment, for example, as described above with respect to FIG. 22, generating OFDM symbols for a data field may include generating a plurality of constellation symbols in a first bandwidth portion of a channel bandwidth and a second And generating OFDM symbols of a data field including a copy of a plurality of constellation symbols in a bandwidth portion. In a further embodiment, a copy of a plurality of constellation symbols is generated that includes a predetermined phase shift.

At block 2704, a preamble of the data unit is generated. The preamble generated in block 2704 is generated to indicate whether the data portion of at least a data unit generated in block 2702 has been generated using a range extension coding technique or a regular coding technique. In various embodiments and / or scenarios, preambles 701 (Figures 9a, 10a), 751 (Figures 9b, 10b), 1101 (Figure 11a), 1151 ), 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 a first portion representing i) the duration of the PHY data unit and ii) a second portion indicating whether at least some OFDM symbols of the data portion are generated according to a range extension coding technique. In a further embodiment, the first portion of the preamble is preambleed to be decodable by a receiver device that does not conform to a first communication protocol (e.g., a HEW communication protocol) but complies with a second communication protocol (e.g., a legacy communication protocol) Wherein a duration of the PHY data unit is determined based on a first portion of the preamble.

In one embodiment, the preamble generated at block 2704 includes a CI indication set to indicate whether at least a data portion has been generated using a range extension coding technique or a regular coding technique. In one embodiment, the CI indication includes 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 in block 2704 is formatted (e.g., without decoding) so that the receiving device can automatically detect whether the preamble corresponds to a regular mode preamble or a range extended mode preamble. In one embodiment, the detection of a range extension mode preamble signals to the receiving device that at least a data portion has been generated using a range extension coding technique.

In one embodiment, the step of generating a preamble comprises the steps of: i) generating a second portion of a preamble that includes second OFDM symbols for at least one copy of a short training field according to a first communication protocol and ii) And generating third OFDM symbols for at least one copy of i) a long training field according to a first communication protocol and ii) a long training field. In a further embodiment, the OFDM symbols, the second OFDM symbols, and the third OFDM symbols for the data portion have the same tone plan as 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 (e.g., a legacy communication protocol), and generating at least some OFDM symbols of the data field in a range extension mode And generating a second signal field with a copy of the first signal field to indicate that the second signal field is generated according to the second signal field. 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 compliant with the first communication protocol as an additional training field It is possible. In another embodiment, the first signal field and the second signal field are decodable in combination by a receiver device compliant with a first communication protocol to increase the decoding reliability of the first signal field and the second signal field.

In one embodiment, the first portion of the preamble includes: i) a legacy short training field conforming to a second communication protocol; ii) a non-legacy long training field; and iii) a legacy signal Field, and the second portion of the preamble does not contain 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 following a second communication protocol, and a second plurality of constellation symbols are generated using a non-legacy tone plan Generated for a non-legacy long training field; And the OFDM symbols for the data field include a third plurality of constellation symbols generated using the non-legacy tone plan.

In one embodiment, OFDM symbols are generated for a first portion of a preamble as a legacy preamble using normal guard intervals following 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, the 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 the normal guard interval, and the OFDM symbols in the second part of the second preamble are generated at the long guard interval RTI ID = 0.0 > non-legacy long training < / RTI > In another embodiment, OFDM symbols are generated for the legacy signal field of the first portion of the preamble using the normal guard interval, and the OFDM symbols are generated for the non-legacy signal field of the second portion of the preamble using the long guard interval . In one embodiment, the second portion of the preamble is decodable by the receiver devices compliant with the first communication protocol and the long guard interval of the second preamble indicates that the PHY data unit is in the range extension mode, Signals to the devices. In yet other embodiments, the OFDM symbols are generated using a long guard interval to generate for a second portion of a preamble for a copy of a first OFDM symbol for a non-legacy signal field and ii) a non-legacy signal field do. In one embodiment, the OFDM symbols are arranged in a first portion of a preamble that includes 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 And is generated for each of the plurality of fields.

At block 2706, the data unit is generated to include the preamble generated at block 2704 and the data portion generated at block 2702. [ In one embodiment, the PHY data unit includes a double guard interval according to a second communication protocol, without a guard interval between the first signal field and the second signal field, followed by a first portion of the signal field and a second portion of the signal field .

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

In another embodiment, 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 are i) a second tone interval different from the first tone interval, and ii) Generated using regular guard interval. In a further embodiment, the second tone spacing of the first portion of the preamble is i) a legacy tone interval following the second communication protocol, and ii) an integer multiple of the first tone interval of the data field; And the regular guard interval is a legacy guard interval following 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 interval and a legacy guard interval, and ii) at least a second OFDM symbol using a first tone interval and a long guard interval . In still other embodiments, the OFDM symbols for the data field include a plurality of constellation symbols in the first bandwidth portion of the channel bandwidth and a first tone portion in the second bandwidth portion of the channel bandwidth, And the first bandwidth portion and the second bandwidth portion have the same bandwidth. In a further embodiment, generating the OFDM symbols for the data field includes generating a copy of the plurality of constellation symbols including a predetermined phase shift.

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

In another embodiment, the step of generating OFDM symbols in a data field of a PHY data unit according to a range extension mode comprises: using non-legacy tone intervals and a non-legacy tone plan that do not conform to a second communication protocol, Generating OFDM symbols; And generating OFDM symbols for a first portion of the preamble using a second tone spacing different from the non-legacy tone interval 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 the direct current tone. In one embodiment, the non-legacy tone plan includes at least one data tone in place of the corresponding guard tone in the legacy tone plan such that the non-legacy tone plan and the legacy tone plan have the same number of data tones. In another embodiment, the non-legacy tone plan includes fewer data tones than the legacy tone plan, and generating the OFDM symbols for the data field using the non-legacy tone interval and non- And encoding the information bits for the OFDM symbols using an error correction code based on a number of data tones in 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 in accordance with one embodiment. Referring to Figure 1, a method 2800 is implemented by the 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 yet another embodiment, the MAC processing 18 is also configured to implement at least a portion of the method 2800. [ Still referring to FIG. 1, in another embodiment, the method 2800 is implemented by a network interface 27 (e.g., PHY processing unit 29 and / or MAC processing unit 28). In other embodiments, the 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 the 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 a 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 are encoded to produce a first plurality of information bits.

At block 2806, in one embodiment, a first plurality of encoded bits is mapped to a first plurality of constellation symbols. At block 2808, in one embodiment, a first plurality of modified constellation symbols is generated, including multiplying a predetermined sequence by a first plurality of constellation symbols. At block 2810, a second plurality of orthogonal frequency division multiplexing (OFDM) symbols is generated comprising a first plurality of modified constellation symbols in an embodiment. At block 2812, a preamble is generated that includes a first plurality of OFDM symbols for a first field and a second plurality of OFDM symbols for a second field in one embodiment. At block 2814, a PHY data unit containing 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 representing the duration of the PHY data unit, and the second plurality of information bits comprises a first set of information bits The preamble is formatted so as to be decodable, but 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 an index.

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

In some embodiments, generating a first plurality of OFDM symbols comprises generating a first plurality of OFDM symbols in a first field generated by a receiver compliant with a first communication protocol to enable automatic detection of a first mode or a second mode by a receiver device, Correlated output to i) generating a first plurality of OFDM symbols to send a first mode of a first communication protocol or ii) a second mode of a first communication protocol do. In one embodiment, the first field comprises a first long training sequence. In another embodiment, the first field comprises 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; Multiplying the second plurality of constellation symbols by the predetermined sequence; generating a second plurality of modified constellation symbols; 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 .

29 is a diagram of an example PHY preamble portion 2900 following a HEW communication protocol, in accordance with one embodiment, as compared to a preamble portion 2904 that conforms to a legacy protocol. In one embodiment, the network interface device 16 of the AP 14 is coupled to the client station 25-1 via orthogonal frequency-domain multiplexing (OFDM) modulation in accordance with an embodiment with a data unit As shown in FIG. In one embodiment, the network interface device 27 of the client station 25-1 is configured to determine whether the data unit comprising the preamble 2900 conforms to the first communication protocol using the 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 to the AP 14 a data unit comprising a PHY preamble 2900. In one embodiment, the network interface device 16 of the AP 14 is configured to determine whether a data unit comprising the preamble 2900 conforms to a first communication protocol using the techniques discussed below.

According to one embodiment, the data unit comprising the PHY preamble 2900 follows the first communication protocol and occupies a 20MHz bandwidth. Data units that conform to the preamble 2900 and that comply with the first communication protocol may include other appropriate bandwidth such as, for example, 40MHz, 80MHz, 160MHz, 320MHz, 640MHz, or in other embodiments, You can take it. The preamble 2900 may be used to send a message to a client station (e.g., legacy client station 25-4) that is in "mixed mode" situations, i.e., the WLAN 10 complies with a legacy communication protocol but does not conform to the first communication protocol 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, 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 that includes a guard interval 2920 and an L-SIG OFDM symbol 2924, according to one embodiment. L-LTF 204/304/504 and L-SIG 206/306/506 may be combined with a first portion of a corresponding legacy preamble 2904 according to an embodiment (e.g., IEEE 802.11a standard, IEEE 802.11 g preamble conforming to the IEEE 802.11n standard, the IEEE 802.11n standard, and / or the IEEE 802.11ac standard). 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, L-SIG 206/306/506 includes a length field set for a value indicating the length of a PHY data unit including 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, a communication device configured to operate in accordance with the first communication protocol senses repetition of L-Sig field 206/306/506 in preamble 2900, and the L-Sig field 206/306/506, Based on the detected reception of the preamble 2900, whether or not the corresponding preamble 2900 complies with the first communication protocol. In one embodiment, upon iterative detection of the L-Sig fields 206/306/506, 2928, the receiving device may, in one embodiment, provide iterative L- 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) (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 enhances the decoding reliability of the L-Sig fields 206/306 / 206/306/506, 2928 in order to combine the detected multiple L-Sig fields 206/306/506, 2928 and / Use information.

In one embodiment, the preamble 2900 further includes a HEW-SIGl field 2932 that includes a DGI 2936 and a HEW-SIGl field OFDM symbol 2940. The preamble 2900 also includes a second HEW-SIGl field 2944. In one embodiment, the HEW-SIGl field 2944 is a copy of the HEW-SIG1 field 2932. In one embodiment, the receiving device compliant with the first communication protocol, in one embodiment, uses a copy that iterates HEW-SIGl fields 2932, 2944 as additional training information to improve channel estimation. In another embodiment, a receiving device that complies with the first communication protocol receives a number of HEW-SIG1 fields 2932, 2944 sensed to improve the decoding reliability of HEW-SIGl fields 2932, 2944 Use redundancy information in multiple HEW-SIG1 fields 2932, 2944 to combine and / or improve channel estimation.

In one embodiment, the receiving device configured according to the first communication protocol is formatted to determine whether the data unit comprising 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. In this embodiment, a receiving device that receives a data unit that includes a preamble 2900 may use the long training sequence of the legacy communication protocol as described above with respect to FIG. 23 in one embodiment to generate LTF 204/304 / RTI > by performing a second cross-correlation of the LTF field 204/304/504 using the first cross-correlation of the first communication protocol and the modified long training sequence of the first communication protocol, The first communication protocol can be detected.

In one embodiment, the preamble portion 3201 of the data unit 3200 is additionally formatted so that the legacy communication device determines whether the data unit 3200 does not conform to the legacy communication protocol. For example, in one embodiment, the receiving device may include a first L-Sig field 3202, a second L-Sig field 3202, and a second L-Sig field 3202 to detect BPSK modulation in OFDM symbols at corresponding locations in the legacy data unit format 3220 3204 and the HEW-SIG1 field 3208 are modulated, respectively. For example, upon BPSK modulation detection in OFDM symbols corresponding to the first L-Sig field 3202, the second L-Sig field 3204 and the HEW-SIG1 field 3206, Will stop processing the data unit 3200 and will refrain from accessing the media for a determined duration based on the L-Sig field 3204. [

FIG. 30 is a diagram of a portion 3000 of an example PHY preamble following a first communication protocol according to another embodiment compared to a portion 2904 of the preamble following a legacy protocol. The preamble 3000 is similar to the preamble 2900 of FIG. 29, and the same-numbered elements are not discussed in detail for the sake of brevity. In one embodiment, the network interface device 16 of the AP 14 is configured to generate and transmit a data unit comprising the PHY preamble 3000 to the client station 25-1 via OFDM modulation according to one embodiment do. In one embodiment, the network interface device 27 of the client station 25-1 uses a technique discussed below to determine whether a data unit comprising the preamble 3000 conforms to a first communication protocol do.

In one embodiment, the network interface device 27 of the client station 25-1 is also configured to generate a data unit comprising the PHY preamble 3000 and transmit it to the AP 14. [ In one embodiment, the network interface device 16 of the AP 14 is configured to use the techniques discussed below to determine whether a data unit comprising the preamble 3000 complies with a first communication protocol.

According to one embodiment, the data unit comprising the PHY preamble 3000 follows the first communication protocol and occupies 20 MHz bandwidth. Data units that conform to the preamble 3000 and that comply with the first communication protocol may include other appropriate bandwidth such as, for example, 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz, or in other embodiments, You can take it. The preamble 3000 may be used to send a message to a client station (e.g., legacy client station 25-4) that is in "mixed mode" situations, ie, the WLAN 10 follows a legacy communication protocol but does not follow the first communication protocol Suitable for inclusion. The preamble 3000, in some embodiments, is also used in other situations.

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

The L-LTF 204/304/504 and the L-SIG 206/306/506 are coupled to a first portion of the corresponding legacy preamble 2904 according to an embodiment (e.g., IEEE 802.11a standard, IEEE 802.11 g preamble conforming to the IEEE 802.11n standard, the IEEE 802.11n standard, and / or the IEEE 802.11ac standard). 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 a PHY data unit including the PHY preamble 3000 in one embodiment.

 In one embodiment, a communication device configured to operate in accordance with the HEW protocol senses repetition of HEW-SIGl fields 3004, 3016 in the preamble 3000, and detects the repetition of the HEW-SIG1 fields 3004, , It is configured to determine whether or not the corresponding preamble 3000 conforms to the HEW communication protocol.

In one embodiment, a receiving device that complies with the HEW protocol, in one embodiment, uses a copy that iterates HEW-SIGl fields 3004 and 3016 as additional training information to improve channel estimation. In another embodiment, a receiving device conforming to the HEW protocol may combine the sensed plurality (3004, 3016) and / or improve channel estimation to improve the decoding reliability of the HEW-SIG1 fields 3004, 3016 And uses redundancy information in a plurality of HEW-SIG1 fields 3004 and 3016. [

31 is a diagram of a portion 3100 of an example PHY preamble that follows a first communication protocol according to another embodiment compared to a portion 2904 of a preamble following a legacy protocol. The preamble 3100 is similar to the preamble 2900 of FIG. 29 and the preamble 3000 of FIG. 30, and the same-numbered elements are not discussed in detail for the sake of brevity.

In one embodiment, the network interface device 16 of the AP 14 is configured to generate and transmit a data unit comprising the PHY preamble 3100 to the client station 25-1 via OFDM modulation according to one embodiment do. In one embodiment, the network interface device 27 of the client station 25-1 is configured to determine whether the data unit comprising the preamble 3100 complies with the first communication protocol using the 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 to the AP 14 a data unit comprising a PHY preamble 3100. In one embodiment, the network interface device 16 of the AP 14 is configured to determine whether the data unit comprising the preamble 3100 complies with the first communication protocol using the techniques discussed below.

According to one embodiment, the data unit comprising the PHY preamble 3100 follows the first communication protocol and occupies 20MHz bandwidth. Data units that conform to the preamble 3100 and that comply with the first communication protocol may include other appropriate bandwidth such as, for example, 40MHz, 80MHz, 160MHz, 320MHz, 640MHz, or other suitable bandwidths in other embodiments It can occupy. The preamble 3100 is used to send a message to a client station (e.g., legacy client station 25-4) that is in "mixed mode" situations, ie, the WLAN 10 follows a legacy communication protocol but does not conform to the first communication protocol Suitable for inclusion. The preamble 3100, in some embodiments, is also used in other situations.

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

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 coupled to a first portion of the corresponding legacy preamble 2904 according to an embodiment (e.g., IEEE 802.11a standard, IEEE 802.11 g preamble conforming to the IEEE 802.11n standard, the IEEE 802.11n standard, and / or the IEEE 802.11ac standard). 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 a PHY data unit including the PHY preamble 3000 in one embodiment.

In one embodiment, the communication device configured to operate in accordance with the HEW protocol detects the 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 determined iteration, determines whether the corresponding preamble 2900 complies with the HEW protocol. In one embodiment, upon iterative detection of the L-Sig fields 206/306/506, 2928, the receiving device may, in one embodiment, provide iterative L- 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) (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 enhances the decoding reliability of the L-Sig fields 206/306 / 206/306/506, 2928 in order to combine the detected multiple L-Sig fields 206/306/506, 2928 and / Use information.

In one embodiment, a communication device configured to operate in accordance with the HEW protocol senses repetition of HEW-SIGl fields 3004, 3016 in the preamble 3000, and detects the repetition of the HEW-SIG1 fields 3004, , It is configured to determine whether or not the corresponding preamble 3000 conforms to the HEW communication protocol.

In one embodiment, a receiving device that complies with the HEW protocol, in one embodiment, uses a copy that iterates HEW-SIGl fields 3004 and 3016 as additional training information to improve channel estimation. In another embodiment, a receiving device conforming to the HEW protocol may combine the sensed plurality (3004, 3016) and / or improve channel estimation to improve the decoding reliability of the HEW-SIG1 fields 3004, 3016 And uses redundancy information in a plurality of HEW-SIG1 fields 3004 and 3016. [

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

The data unit including the preamble 3200 follows the first communication protocol and occupies 20MHz bandwidth. Data units conforming to the first communication protocol having preambles with similar preambles in the preamble 3200 may be used to transmit other suitable bandwidths, for example 40MHz, 80MHz, 160MHz, 320MHz, 640MHz, or in other embodiments, have. The data unit comprising the preamble 3200 may be used in a " mixed mode " situations where a WLAN 10 complies with a legacy communication protocol but does not conform to a first communication protocol (e.g., a legacy client station 25 -4)). Preamble 3200, in some embodiments, is also used in other situations.

The preamble 3200 includes a long training field 3204 having a first long guard interval 3202, a first portion 3204-1 and a second portion 3204-2, a second long guard interval 3206, 1 L-Sig field 3206-1, a second L-Sig field 3206-2, a third long guard interval 3202, a first HEW signal field HEW-SIG1 3208, a fourth long guard interval 3202) and a second HEW signal field HEW-SIG2 (3210). 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 corresponds to the first L- It is a copy of the Sig field 3602-1. In one embodiment, each long guard interval 3202 is a double grard interval that is twice as long as the normal guard interval defined by the legacy communication protocol. For example, in one embodiment, the normal guard interval defined by the legacy communication protocol is 0.8 占 퐏, but the double guard interval is 1.6 占 퐏. In another embodiment, each long guard interval 3202 has another suitable value that is 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 ㎲, but in various embodiments the long guard interval is another suitable value greater than 1.2,, 2.4 3.2, 3.2,, or 0.8 ㎲.

With continued reference to Figure 32, a legacy data unit format 3220 is illustrated for reference. The data unit following format 3220 includes a long guard field 3224 having a double guard interval 3222, a first portion 3224-1 and a second portion 3224-2, a first regular guard interval 3225, , An L-Sig field 3226, an OFDM symbol 3228 corresponding to a signal field (e.g., an HT-SIG1 field or a VHT-SIG1 field), or a data unit 3200 dependent on a particular legacy protocol An OFDM symbol 3230 corresponding to an OFDM symbol of a data portion, a third regular guard interval 3225 and a signal field (for example, an HT-SIG2 field or a VHT-SIG2 field) And OFDM symbols of data portions that depend on a particular legacy protocol.

In one embodiment, a receiving device compliant with the first communication protocol is formatted with a preamble portion 3201 of the data unit 3200 to determine 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 corresponds to the modified legacy signal Field 2306 in Fig. In this embodiment, the receiving device receiving the data unit 3200 is configured to receive the first of the long training fields 3202 using the long training sequence of the legacy communication protocol, as described above with respect to FIG. 23 in one embodiment. 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 complies with the first communication protocol . Additionally or alternatively, in one embodiment, the receiving device receiving the data unit 3200 can detect the presence of the second L-Sig field 3205 in the preamble portion 3201, It can detect that it complies with the communication protocol.

In one embodiment, the preamble portion 3201 of the preamble 3200 is additionally formatted so that the legacy communication device determines whether the data unit comprising the preamble 3200 does not conform to the legacy communication protocol. For example, in one embodiment, the receiving device may include a first L-Sig field 3202, a second L-Sig field 3202, and a second L-Sig field 3202 to detect BPSK modulation in OFDM symbols at corresponding locations in the legacy data unit format 3220 3204 and the HEW-SIG1 field 3208 are modulated, respectively. For example, upon BPSK modulation detection in OFDM symbols corresponding to the first L-Sig field 3202, the second L-Sig field 3204 and the HEW-SIG1 field 3206, Will stop processing the data unit 3200 and will refrain from accessing the media for a determined duration based on the L-Sig field 3204. [ 32, in one embodiment, the first L-Sig field 3204 in the time domain is associated with the corresponding OFDM symbol in the legacy preamble 3220 due to the long guard interval preceding the L-Sig field 3210. [ It is not aligned with the 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 second L-Sig field 3206-1 are arranged such that constellation points are shown as BPSK in the shifted FFT window used by the legacy communication device with the corresponding OFDM symbols of the legacy format 3220, 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 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 twice as long as the normal guard interval is defined by the legacy communication protocol, the length of each of the first L-Sig field 3206-1 and the HEW-SIG1 field 3208 The constellation points are rotated by 90 degrees as described above with respect to Figures 14b-14c. As a result, 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 performs BPSK modulation . In this embodiment, the cyclic prefix of the second L-Sig field 3206-2 is not matched to the last portion 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 is configured for the network interface device 16 of the AP 14 to generate via OFDM modulation according to one embodiment and to transmit to the client station 25-1. In one embodiment, the network interface device 27 of the client station 25-1 is configured to determine whether the data unit comprising the preamble 3300 complies with the first communication protocol using the techniques discussed below do.

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

The data unit including the preamble 3300 follows the first communication protocol and occupies 20MHz bandwidth. Data units having preambles similar to the preamble 3300 and compliant with the first communication protocol may occupy other appropriate bandwidths such as, for example, 40MHz, 80MHz, 160MHz, 320MHz, 640MHz, or in other embodiments, have.

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

In one embodiment, the L-Sig field 3206 and the second HEW-SIGl field 3208-2 are each aligned to its corresponding OFDM symbol in the legacy format 3220. [ On the other hand, the first HEW-SIGl field 3208-1 is not aligned with its corresponding OFDM symbol in the legacy format 3220. [ In one embodiment, the constellation points of the first HEW-Sig field 3208-1 are pre-rotated so that the receiving device senses BPSK modulation in the shifted FFT window corresponding to the OFDM symbol 3228 (e.g., 90 degrees). In one embodiment, the second HEW-SIG1 field 3208-2 is modulated using BPSK modulation such that the receiving device can detect BPSK modulation of the corresponding OFDM symbol 3330 in the legacy format 3200. [ However, in this case, the modulation of the second HEW-SIG1 field 3208-2 (BPSK) in one embodiment is the modulation of the first HEW-SIG1 field 3208-1 (e.g., R-QBPSK) different. As a result, the cyclic prefix of the second HEW-SIG 1 field 3208-2 is not exactly matched to the corresponding last portion of the first HEW-SIG1 field 3208-1.

Alternatively, in another embodiment, the second HEW-SIG1 field 3208-2 is modulated in the same modulation scheme as the first HEW-SIG1 field 3208-1 (e.g., R-QBPSK). In this embodiment, the cyclic prefix of the second signal field HEW-SIG1 field 3208-2 matches the last portion of the first signal field HEW-SIG1 field 3208-1, and the non-legacy device matches the preamble 3300 To detect more accurately whether or not the data unit containing the data unit 3300 corresponds to the first communication protocol based on the detection of the repetition of the HEW-SIG1 field in the data unit 3300. [ Furthermore, in this embodiment, the legacy device will sense shifted modulation (e.g., quadrature phase shift keying) in the corresponding OFDM symbol 3230, which may be a data unit in accordance with the IEEE-802-11ac standard 3200). ≪ / RTI > However, the legacy device will interpret the second HEW-SIGl field 3208-2 as the VHT-SIG2 field and fail the CRC check of the VHT-SIG2 field. In one embodiment, the legacy device, in accordance with the IEEE 802.11ac standard, would then discard the data unit with the preamble 3300 and inhibit the blanket media access indicated in the L-Sig field 3206 in one embodiment . Various methods for ensuring that the legacy device detects a CRC error based on the decoding of the second HEW-SIGl field 3208-2 are described in U.S. Pat. Patent application no. 13 / 856,277, (Attorney Docket No. MP4709), which is hereby incorporated by reference in its entirety.

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

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

The data unit including the preamble 3400 follows the first communication protocol and occupies 20MHz bandwidth. Data units that have similar preambles to the preamble 3400 and comply with the first communication protocol may receive other suitable bandwidth such as, for example, 40MHz, 80MHz, 160MHz, 320MHz, 640MHz, or in other embodiments, have.

The preamble 3400 includes a preamble portion 3401 that includes long guard intervals between OFDM symbols of the preamble portion 3401 and includes no redundancy of the L-Sig field 3206, 32, except that the preamble 3200 of FIG. Additionally, unlike the preamble 3200, the pre-rotation of the constellation points in the OFDM symbols of the preamble 3400 in the illustrated embodiment is not aligned to the corresponding OFDM symbols in the legacy format 3220 Do not.

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

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

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

FIG. 36 is a diagram of an example PHY preamble portion 3600 following a first communication protocol, according to another embodiment, in comparison to the portion 2904 of the preamble following the legacy protocol. The preamble 3600 is similar to the preamble 2900 of FIG. 29, and the same-numbered elements are not discussed in detail for purposes of simplicity.

In one embodiment, the network interface device 16 of the AP 14 is configured to generate and transmit a data unit comprising a PHY preamble 3600 to the client station 25-1 via OFDM modulation according to one embodiment. do. In one embodiment, the network interface device 27 of the client station 25-1 is configured to determine whether a data unit comprising the preamble 3600 complies with the first communication protocol using the techniques discussed below do.

In one embodiment, the network interface device 27 of the client station 25-1 is also configured to generate a data unit containing the PHY preamble 3600 and transmit it to the AP 14. [ In one embodiment, the network interface device 16 of the AP 14 is configured to determine whether a data unit comprising the preamble 3600 complies with a first communication protocol using techniques discussed below.

According to one embodiment, the data unit comprising the PHY preamble 3600 follows the first communication protocol and occupies a 20MHz bandwidth. Data units that conform to the preamble 3600 and that conform to the first communication protocol may include other appropriate bandwidths, such as, for example, 40MHz, 80MHz, 160MHz, 320MHz, 640MHz, or other suitable bandwidths in other embodiments You can take it. The preamble 3600 is used to send a message to a client station (e.g., legacy client station 25-4) that is in "mixed mode" situations, ie, the WLAN 10 follows a legacy communication protocol but does not conform to the first communication protocol Suitable for inclusion. Preamble 3600, in some embodiments, is also used in other situations.

In one embodiment, the HEW-Sig field 3604 in the time domain is associated with the corresponding OFDM symbol (V) HT-SIG1 in the legacy preamble 2904 due to the long guard interval 2936 preceding the HEW-SIG1 OFDM symbol 2940 Field 3608. < / RTI >

In one embodiment, the constellation points of the HEW-SIGl OFDM symbol 2940 are rotated by an amount determined by the length of the long guard interval 2936 by the duration of the long guard interval 2936. [ For example, in one embodiment, where the guard interval is defined by a legacy communication protocol, the long guard interval is doubled. The constellation points of the HEW-SIGl OFDM symbol 2940 are described above with respect to Figures 14b-14c It is rotated by 90 degrees. As a result, in one embodiment the HEW-SIGl field 3604 is modulated using the inverted QBPSK (R-QBPSK) modulation.

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

The data unit including preamble 3700 follows the first communication protocol and occupies 20MHz bandwidth. Data units comprising preambles similar to the preamble 3700 and compliant with the first communication protocol may include other suitable bandwidth such as, for example, 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz, or in other embodiments, .

The preamble 3700 is the same as the preamble 3300 of FIG. 33 except that the preamble 3700 omits the second (replica) HEW-SIG1 field 3208-2 and includes the auto-sense OFDM symbol 3706. [ Lt; / RTI > In one embodiment, the receiving device can detect whether a data unit containing the preamble 3700 complies with the first communication protocol based on the detection of the auto-sensing OFDM symbol 3706 in the data unit 3700 have. In the illustrated embodiment, the auto-sense symbol 3706 is immediately after the L-Sig field 3206. [ The auto-detect symbol 3706 is arranged in its corresponding OFDM symbol in the legacy data unit format 3220 and is arranged for at least non-zero tones of the tones of the corresponding OFDM symbol in the legacy format 3220 in one embodiment 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 to the corresponding OFDM symbol in the legacy format 3220. [ In one embodiment, the constellation points of the HEW-SIG1 field 3208 are pre-rotated so that the legacy receiving device senses BPSK modulation using the FFT window of the corresponding OFDM symbol in the legacy format 3220 (e.g., 90 degrees).

Figures 38a-38d are diagrams illustrating the auto-sensing OFDM symbol 3706 of the data unit 3700 in accordance with some representative embodiments. Going first to Figure 38A, in one embodiment, the auto-sensing OFDM symbol 3706 includes five iterations of the L-LTF sequence defined by legacy communication protocols. In this embodiment, the non-legacy receiving device reuses the start of the packet sensing algorithm used to sense the beginning of the data unit 3700 based on the L-STF field included at the beginning of the data unit 3700, Unit 3700 is in compliance with the first communication protocol. Going now to Figure 38b, in one embodiment, the auto-sensing OFDM symbol 3706 includes two (or more) of the appropriate predetermined sequence (corresponding to more OFDM tones) as compared to the L- STF sequence defined by the legacy communication protocol Lt; / RTI > For example, the predetermined sequence may be different for each OFDM tone (e.g., set [+/- 2, +/- 4, +/- 6 , Etc.] OFDM tones with inner indices). Going now to 38c, in one embodiment, the auto-sensing OFDM symbol 3706 includes five iterations of the last portion of the L-Sig field 3206 (e.g., lasting 0.8 占 퐏). 38c, auto-sensing OFDM symbol 3706 may comprise two iterations of a large portion (e.g., 1.6 占 퐏) of the L-Sig field 3206, followed by an L-Sig field Includes a sub-portion of a large portion (e. G., 0.8 mu s) of the sub-portion 3206 (e.

In other embodiments, the auto-sensing OFDM symbol 3706 may comprise any other suitable pre-amble available for use at the receiving device to auto-sense whether the data unit comprising the preamble 3700 conforms to the first communication protocol And includes the determined sequence. For example, the auto-sensing OFDM symbol 3706 includes a predetermined Barker code sequence, a predetermined Golay code sequence, or any other suitable predetermined sequence in various embodiments . In one embodiment, by sensing a high correlation of the auto-sensing OFDM symbol 3706 with a predetermined sequence, the receiving device senses whether the data unit comprising the preamble 3700 complies with the first communication protocol.

39 is a diagram of a portion 3900 of an example PHY preamble that follows a first communication protocol according to another embodiment compared to a portion 2904 of a preamble following 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 the sake of brevity.

In one embodiment, the network interface device 16 of the AP 14 is configured to generate and transmit a data unit comprising a PHY preamble 3900 to the client station 25-1 via OFDM modulation according to one embodiment. do. In one embodiment, the network interface device 27 of the client station 25-1 uses the techniques discussed below to determine whether the data unit comprising the preamble 3900 conforms to the first communication protocol do.

In one embodiment, the network interface device 27 of the client station 25-1 is also configured to generate a data unit containing the PHY preamble 3900 and transmit it to the AP 14. [ In one embodiment, the network interface device 16 of the AP 14 is configured to determine whether the data unit comprising the preamble 3900 conforms to the first communication protocol using the techniques discussed below.

According to one embodiment, the data unit comprising the PHY preamble 3900 follows the first communication protocol and occupies 20MHz bandwidth. Data units that conform to the preamble 3900 and that comply with the first communication protocol may include other appropriate bandwidth such as, for example, 40MHz, 80MHz, 160MHz, 320MHz, 640MHz, or in other embodiments, You can take it. The preamble 3900 is used to send a message to a client station (e.g., legacy client station 25-4) that is in "mixed mode" situations, ie, the WLAN 10 follows a legacy communication protocol but does not follow the first communication protocol Suitable for inclusion. The preamble 3900, in some embodiments, is also used in other situations.

SIG1 2944 according to one embodiment is modulated using BPSK while L-SIG 206/36/506, L-SIG 2928 and HEW-SIG1 2932 are modulated using BPSK, while HEW- For example, Q-BPSK).

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

In one embodiment, the network interface device 16 of the AP 14 is configured to generate and transmit a data unit comprising the PHY preamble 4000 to the client station 25-1 via OFDM modulation according to one embodiment. do. In one embodiment, the network interface device 27 of the client station 25-1 is configured to determine whether a data unit comprising the preamble 4000 complies with the first communication protocol using the techniques discussed below do.

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

According to one embodiment, a data unit comprising a PHY preamble 4000 follows a first communication protocol and occupies a 20 MHz bandwidth. Data units that conform to the preamble 4000 and that conform to the first communication protocol may include other appropriate bandwidth such as, for example, 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz, or in other embodiments, You can take it. The preamble 4000 may be used in a " mixed mode " situations where the WLAN 10 is a client station (e.g., legacy client station 25-4) that conforms to the legacy communication protocol but does not conform to the first communication protocol Suitable for inclusion. The preamble 4000, in some embodiments, is also used in other situations.

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 a guard interval is included between the L-LTF OFDM symbol 4012 and the L-SIG OFDM symbol 4016. According to one embodiment, the legacy device may decode the L-SIG 4016 and determine the length of the PHY data unit that includes the PHY preamble 4000. [ For example, the L-SIG 4016 includes a set of length fields for a value indicating the length of a PHY data unit that includes 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. do. In this embodiment, the receiving device compliant with the first communication protocol uses a long training sequence of the legacy communication protocol as described above with respect to FIG. 23 in one embodiment to generate a first cross- Correlations and a modified long training sequence of the first communication protocol to perform a second cross-correlation of the L_LTF field 4012 to determine whether the data unit comprising the preamble 4000 complies with the first communication protocol Can be detected.

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, HEW-SIGB OFDM symbol 4036. In one embodiment, DGI is included between L-SIG 4016 and HEW-STF 4020a. LTF1 OFDM symbol 4024 and the HEW-SIGA OFDM symbol 4028, between the HEW-STF OFDM symbol 4020b and the HEW-LTF1 OFDM symbol 4024, between the HEW-LTF1 OFDM symbol 4024 and the HEW- Between the OFDM symbol 4028 and one or more HEW-LTFs OFDM symbols 4032 and between one or more HEW-LTFs OFDM symbols 4032 and the HEW-SIGB OFDM symbol 4036.

FIG. 40B is a diagram of a portion 4050 of another example PHY preamble following a first communication protocol according to another embodiment. The preamble portion 4050 is similar to the preamble portion 4000 and the same-numbered elements are not discussed in detail for the sake of brevity.

In one embodiment, the network interface device 16 of the AP 14 is configured to generate and transmit a data unit comprising the PHY preamble 4050 to the client station 25-1 via OFDM modulation according to one embodiment do. In one embodiment, the network interface device 27 of the client station 25-1 is configured to determine whether the data unit comprising the preamble 4050 complies with the first communication protocol using the techniques discussed below do.

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

According to one embodiment, the data unit comprising the PHY preamble 4050 follows the first communication protocol and occupies 20MHz bandwidth. Data units that conform to the preamble 4050 and that comply with the first communication protocol may include other appropriate bandwidth such as, for example, 40MHz, 80MHz, 160MHz, 320MHz, 640MHz, or in other embodiments, It can occupy. The preamble 4050 may be used in a " mixed mode " situations, i.e. a client station (e.g., a legacy client station 25-4) that conforms to the legacy communication protocol but does not conform to the first communication protocol Suitable for inclusion. Preamble 4050, in some embodiments, is also used in other situations.

According to one embodiment, the legacy device may decode the L-SIG 4016 and determine the length of the PHY data unit that includes the PHY preamble 4050. [ For example, L-SIG 4016 includes a set of length fields for a value indicating the length of a PHY data unit that includes 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. do. In this embodiment, the receiving device compliant with 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 generate a first cross- Correlations and a modified long training sequence of the first communication protocol to perform a second cross-correlation of the L_LTF field 4012 to determine whether the data unit comprising the preamble 4050 complies with the first communication protocol Can be detected.

Additionally or alternatively, in one embodiment, a receiving device receiving a data unit comprising a preamble 4050 may detect the presence of one or more second L-Sig fields 4054 in the preamble portion 4050, Can be detected to comply with the first communication protocol.

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

In some embodiments, techniques such as those described above may be used to detect data units that conform to a first communication protocol and to detect any of a plurality of modes (defined by a first communication protocol) . For example, FIG. 41 is a diagram of a portion 4100 of an example PHY preamble that follows a first communication protocol according to another embodiment compared to a portion 2904 of a preamble following a legacy protocol. In addition, the PHY preamble 4100 also corresponds to the range extension mode of the first communication protocol. 41 also includes a diagram of a portion 4104 of an example PHY preamble following a first communication protocol according to another embodiment compared to a portion 2904 of a preamble following a 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 communicates with the client station 25-1 via OFDM modulation in accordance with an embodiment with a data unit (not shown) including a PHY preamble 4100 or a PHY preamble 4104 As shown in FIG. In one embodiment, the network interface device 27 of the client station 25-1 uses the techniques discussed below to determine whether the data unit comprising the preamble 4100 or preamble 4104 complies with the first communication protocol Or < / RTI > In one embodiment, the network interface device 27 of the client station 25-1 uses the techniques discussed below to determine whether the data unit comprising the preamble 4100 conforms to the range extension mode and the preamble 4104 To determine whether the containing data unit follows a regular mode.

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

According to one embodiment, the data unit comprising the PHY preamble 4100 follows the first communication protocol and occupies a 20MHz bandwidth. Data units that conform to the preamble 4100 and that conform to the first communication protocol may include other suitable bandwidths, such as, for example, 40MHz, 80MHz, 160MHz, 320MHz, 640MHz, or in other embodiments, You can take it. According to one embodiment, the data unit comprising the PHY preamble 4104 follows the first communication protocol and occupies 20MHz bandwidth. Data units that conform to the preamble 4104 and that conform to the first communication protocol may include other suitable bandwidth such as, for example, 40MHz, 80MHz, 160MHz, 320MHz, 640MHz, or in other embodiments, You can take it.

The preamble 4100 is similar to the preamble 2900 of FIG. 29, and the same-numbered elements are not discussed in detail for purposes of simplicity. 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, L-SIG 206/306/506 includes a set of length fields for a value indicating the length of a PHY data unit including PHY preamble 4100 in one embodiment.

In one embodiment, the communication device configured to operate in accordance with the HEW protocol detects the 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 Based on the determined iteration, determines whether the corresponding preamble 4100 complies with the first communication protocol. Additionally, the communication device configured to operate in accordance with the first communication protocol determines whether the preamble 4100 follows the range extension mode of the first communication protocol, based on the detected iteration of the L-Sig field 206/306/506 .

The preamble 4104 includes a DGI 4104, an L-LTF 4108, an L-LTF 4112, a GI 4116, and an 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. do. In this embodiment, a receiving device that complies with a first communication protocol uses a long training sequence of a legacy communication protocol as described above with respect to FIG. 23 in one embodiment to generate a first cross- Correlations and a modified long training sequence of the first communication protocol to perform a second cross-correlation of the L_LTF field 4112 to determine whether the data unit comprising the preamble 4104 complies with the first communication protocol Can be detected. In a similar manner, a receiving device compliant with the first communication protocol may sense whether a data unit comprising the preamble 4104 conforms to the normal 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, a receiving device that complies with the HEW protocol uses a long training sequence of legacy communication protocols as described above with respect to FIG. 23 in one embodiment to generate a first cross-correlation of L-LTF 2912 And performing a second cross-correlation of the L_LTF field 2916 using a modified long training sequence of the first communication protocol to detect whether the data unit comprising the preamble 4100 complies with the HEW communication protocol have.

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

In one embodiment, the network interface device 16 of the AP 14 communicates with the client station 25-1 via OFDM modulation in accordance with an embodiment with a data unit (not shown) including a PHY preamble 4200 or a PHY preamble 4204 As shown in FIG. In one embodiment, the network interface device 27 of the client station 25-1 uses the techniques discussed below to determine whether the data unit comprising the preamble 4200 or preamble 4204 complies with the first communication protocol Or < / RTI > In one embodiment, the network interface device 27 of the client station 25-1 uses the techniques discussed below to determine whether the data unit comprising the preamble 4200 complies with the range extension mode and which preamble 4204 To determine whether the containing data unit conforms to the normal mode.

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

According to one embodiment, the data unit comprising the PHY preamble 4200 follows the first communication protocol and occupies 20MHz bandwidth. Data units that conform to the preamble 4200 and that conform to the first communication protocol may include other suitable bandwidths, such as, for example, 40MHz, 80MHz, 160MHz, 320MHz, 640MHz, or in other embodiments, It can occupy. According to one embodiment, the data unit comprising the PHY preamble 4204 follows the first communication protocol and occupies 20MHz bandwidth. Data units that conform to the preamble 4204 and that conform to the first communication protocol may include other appropriate bandwidth such as, for example, 40MHz, 80MHz, 160MHz, 320MHz, 640MHz, or other suitable bandwidths in other embodiments It 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 simplicity. 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, the communication device configured to operate in accordance with the first communication protocol senses the repetition of HEW-SIG1 fields 3004, 3016 in preamble 4200, Based on the iteration, it is configured to determine 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 whether the preamble 4200 follows the range extension mode of the first communication protocol, based on the detected iteration of the HEW-SIGl fields 3004, 3016 .

The preamble 4204 is similar to the preamble 4104 of FIG. 41, and the same-numbered elements are not discussed in detail for the sake of brevity. In one embodiment, the L_LTF field 4112 corresponds to the modified LTF field 2304 of FIG. 23, and in one embodiment, the L-SIG 4120 corresponds to the modified legacy signal field 2306 of FIG. do. In this embodiment, a receiving device that complies with a first communication protocol uses a long training sequence of a legacy communication protocol as described above with respect to FIG. 23 in one embodiment to generate a first cross- Correlations and a modified long training sequence of the first communication protocol to perform a second cross-correlation of the L_LTF field 4112 to determine whether the data unit comprising the preamble 4104 complies with the first communication protocol Can be detected. In a similar manner, a receiving device compliant with the first communication protocol may sense whether a data unit comprising the preamble 4104 conforms to the normal 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 compliant with the first communication protocol uses a long training sequence of the legacy communication protocol as described above with respect to FIG. 23 in one embodiment to generate a first cross- Correlations of the L_LTF field 2916 using the correlation and the modified long training sequence of the first communication protocol to detect whether the data unit comprising the preamble 4200 complies with the HEW communication protocol can do.

43 is a diagram of a portion 4300 of an example PHY preamble following a first communication protocol according to another embodiment compared to a portion 2904 of a preamble following a legacy protocol. In addition, the PHY preamble 4300 also corresponds to the range extension mode of the first communication protocol. Figure 43 also includes a diagram of a portion 4304 of an example PHY preamble that conforms to a first communication protocol according to another embodiment compared to a portion 2904 of a preamble following a legacy protocol. In addition, 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 communicates with the client station 25-1 via OFDM modulation according to one embodiment a data unit (e.g., a PHY preamble 4300 or a PHY preamble 4304) As shown in FIG. In one embodiment, the network interface device 27 of the client station 25-1 uses the techniques discussed below to determine whether the data unit comprising the preamble 4300 or the preamble 4304 complies with the first communication protocol Or < / RTI > In one embodiment, the network interface device 27 of the client station 25-1 uses the techniques discussed below to determine whether the data unit comprising the preamble 4300 conforms to the range extension mode and the preamble 4304 To determine whether the containing data unit conforms to the normal mode.

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

According to one embodiment, the data unit comprising the PHY preamble 4300 follows the first communication protocol and occupies a 20MHz bandwidth. Data units that conform to the preamble 4300 and that comply with the first communication protocol may include other appropriate bandwidth such as, for example, 40MHz, 80MHz, 160MHz, 320MHz, 640MHz, or in other embodiments, It can occupy. According to one embodiment, the data unit comprising the PHY preamble 4304 follows the first communication protocol and occupies a 20MHz bandwidth. Data units conforming to the first communication protocol may include other preamble similar to the preamble 4304 and may include other appropriate bandwidth such as for example 40MHz, 80MHz, 160MHz, 320MHz, 640MHz, or in other embodiments, It can occupy.

The preamble 4300 is similar to the preamble 2900 of FIG. 29, and the same-numbered elements are not discussed in detail for the sake 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, L-SIG 206/306/506 includes a set of length fields for a value indicating the length of a PHY data unit including PHY preamble 4300 in one embodiment.

Data unit 4300 is the same as data unit 2900 of Figure 29 except that data unit 4300 omits the second (replica) L-Sig field 2928 and includes auto-sense OFDM symbol 4308. [ ). In one embodiment, the receiving device compliant with the first communication protocol determines whether the data unit comprising the preamble 4300 conforms to the first communication protocol based on the detection of the auto-sensing OFDM symbol 4308 in the preamble 4300 Can be detected. In the illustrated embodiment, the auto-sense symbol 4308 is immediately after the L-Sig field 206/306/506. The auto-detect 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, a receiving device compliant with the first communication protocol is configured to receive a data unit (not shown) including a preamble 4300 based on sensing auto-sense OFDM symbol 4308 in preamble 4300, The first communication protocol can be detected.

The preamble 4304 is similar to the preamble 4104 of FIG. 41, and the same-numbered elements are not discussed in detail for the sake of brevity. In one embodiment, the L_LTF field 4112 corresponds to the modified LTF field 2304 of FIG. 23, and in one embodiment, the L-SIG 4120 corresponds to the modified legacy signal field 2306 of FIG. do. In this embodiment, a receiving device that complies with a first communication protocol uses a long training sequence of a legacy communication protocol as described above with respect to FIG. 23 in one embodiment to generate a first cross- Correlations of the L_LTF field 4112 using the correlation and the modified long training sequence of the first communication protocol to determine whether the data unit comprising the preamble 4304 complies with the first communication protocol Can be detected. In a similar manner, a receiving device conforming to the first communication protocol may sense whether the data unit comprising the preamble 4304 conforms to the normal 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 that complies with 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 generate a first cross-correlation of the L-LTF 2912 And 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 comprising the preamble 4300 complies with the first communication protocol .

In various other embodiments, techniques such as those described above with respect to Figures 9a-28 may be used to determine whether a receiver compliant with a first communication protocol is capable of: i) determining whether a data unit complies with a first communication protocol; and ii) It will be appreciated that those described above with respect to Figures 29-40b that are utilized to enable determining which of the various different modes of the first communication protocol (e.g., range extension mode, normal mode, etc.) It is combined with the same technologies.

In some embodiments where the Sig field is duplicated (e.g., 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 tl) 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, the BPSK symbols s are mapped sequentially in the first SIG OFDM symbol, while the same BPSK symbols s are cyclically mapped to half of the tones in the second SIG OFDM symbol and is cyclically shifted. In other embodiments, other suitable time varying tones are utilized to obtain time diversity over different SIG OFDM symbols.

In one embodiment, time diversity over different SIG OFDM symbols is implemented using different interleavers for the same coded bits on 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 complies with the first communication protocol, the L-Sig field in the preamble following the first communication protocol corresponds to L-SIG in the legacy preamble multiplied by the sequence ck:

(방정식 6)

(Equation 6)

Here, k is a tone index. In one embodiment, the sequence _ck is a sequence having values of 占.

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

In some embodiments, the HEW-Sig field includes data unit duration information, such as multiple bytes in a data unit, multiple OFDM symbols in a data unit, and so on.

In some embodiments, the fact that including a replica of the HEW-Sig field in the preamble causes a legacy device (e.g., an IEEE 802.11ac receiver) to generate a SIGA CRC error with a 100% probability in the Sig field in the legacy preamble For example, a HEW-Sig field corresponding to SIGA is constructed. For example, in various embodiments, the bits in the HEW-Sig field are scrambled and include a one-bit field set to ensure that the SIGA CRC is in an error state. In another embodiment, the HEW-Sig field is designed to include bits corresponding to the unrecognized 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 includes generating a PHY preamble for the PHY data unit in a first communication device, the step of generating the PHY preamble includes: generating a signal field, including replicating a signal field and a signal field in a PHY preamble Wherein the first portion of the PHY preamble follows a second communication protocol to determine the duration of the PHY data unit based on the first portion of the PHY preamble, And formatting the PHY preamble so as to be decodable by the communication device. The method also includes, in the first communication device, generating 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 a first portion of the PHY preamble; And the legacy signal field includes information indicating the duration of the PHY data unit.

Wherein generating the PHY preamble for the PHY data unit further comprises: generating an additional signal field compliant with 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 by the second communication device.

Generating the PHY preamble for the PHY data unit further comprises: including a replica 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 replica 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, wherein the second signal field is used to indicate the PHY data unit to a duration Generating a second signal field, the second signal field including information, including the second signal field in a first portion of the PHY preamble; And And including the first signal field in a second portion of the PHY preamble.

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

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

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

In another embodiment, a first communication device includes a network interface device having one or more integrated circuits, wherein the one or more integrated circuits are configured to: generate a physical layer (PHY) preamble for the PHY data unit compliant with a first communication protocol Wherein generating the physical layer preamble includes generating a signal field, including a replica of a signal field and a signal field in a PHY preamble, and determining a duration of the PHY data unit based on a first portion of the PHY preamble The first portion of the PHY preamble following the second communication protocol to decode the PHY preamble so as to be decodable by the second communication device not following the first communication protocol. The one or more integrated circuits are also configured to generate the PHY data unit comprising 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; Wherein 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 the 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 to include the additional signal field in a second portion of the PHY preamble.

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

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

The one or more integrated circuits are configured to include a replica of the additional signal field in a 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, wherein the second signal field includes information indicating a duration of the PHY data unit, Including the second signal field in a first portion; And to include the first signal field in a second portion of the PHY preamble.

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

Wherein the one or more integrated circuits include an individual 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 an individual second guard interval between OFDM symbols in the PHY payload to generate the PHY payload, wherein each second guard interval has a duration that is longer than a respective first guard interval .

The one or more integrated circuits are configured to generate the PHY preamble including an individual 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-implemented firmware instructions, processor-implemented software instructions, or any combination thereof. When implemented using a processor that executes software or firmware instructions, the software or firmware instructions may be stored in any non-volatile, type of computer readable medium or media such as magnetic disk, optical disk, random access memory (RAM) A dedicated memory (ROM), a flash memory, a magnetic tape, or the like. The software or firmware instructions may include machine-readable instructions that, when executed by one or more processors, cause one or more processors to perform the various steps.

When implemented in hardware, the hardware may include one or more of discrete components, an integrated circuit, an application specific integrated circuit (ASIC), a programmable logic device (PLD), and the like.

While the present invention has been described with reference to specific examples, which are intended to be illustrative only and not intended to be limiting of the invention, it is to be understood that changes, additions, and / or deletions can be made to the disclosed embodiments without departing from the scope of the invention have.

Claims (20)

CLAIMS What is claimed is: 1. 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,
In a first communication device, generating a PHY preamble for the PHY data unit,
Generating a signal field;
Including a replica of the signal field and the signal field in the PHY preamble, and
Wherein the first portion of the PHY preamble follows a second communication protocol but does not conform to the first communication protocol to determine a duration of the PHY data unit based on the first portion of the PHY preamble. Formatting the PHY preamble so as to be decodable by the device; generating the PHY preamble; And
And in the first communication device, generating the PHY data unit comprising the PHY preamble and a PHY payload. The method according to claim 1,
The signal field is a legacy signal field decodable by the second communication device;
The legacy signal field is included in a first portion of the PHY preamble; And
Wherein 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 second communication protocol; and
Further including the additional signal field in a 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 second communication device. 4. The method of claim 3, wherein generating the PHY preamble for the PHY data unit comprises:
Further including a replica of the additional signal field in a second portion of the PHY preamble. The method of claim 1, wherein generating the PHY preamble for the PHY data unit comprises:
Further including a replica of the additional signal field in a second portion of the PHY preamble. The method according to claim 1,
The signal field is a first signal field; And
Wherein 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 including information indicating a duration of the PHY data unit; generating the second signal field;
Including the second signal field in a first portion of the PHY preamble; And
And including the first signal field in a second portion of the PHY preamble. 8. The method of claim 7, wherein the second portion of the PHY preamble is not decodable to the second communication device. The method according to claim 1,
Wherein the PHY preamble for the PHY data unit is generated by including an individual first guard interval between orthogonal frequency domain (OFDM) symbols in a first portion of the PHY preamble; And
The method may further comprise, in the first communication device, generating the PHY payload including an individual second guard interval between OFDM symbols in the PHY payload, wherein each second guard interval comprises Wherein the first guard interval has a duration longer than the first guard interval of the first guard interval. The method of claim 9, wherein the PHY preamble for the PHY data unit is generated by including an individual second guard interval between OFDM symbols in a second portion of the PHY preamble. In the first communication apparatus,
A network interface device having one or more integrated circuits, wherein the one or more integrated circuits comprise:
Generating a physical layer (PHY) preamble for the PHY data unit conforming to a first communication protocol,
Generating a signal field,
Including a replica of the signal field and the signal field in the PHY preamble; and
Wherein the first portion of the PHY preamble follows a second communication protocol but does not conform to the first communication protocol to determine a duration of the PHY data unit based on the first portion of the PHY preamble. Formatting the PHY preamble to be decodable by the device; And
The PHY data unit comprising the PHY preamble and the PHY payload. The method of claim 11,
The signal field is a legacy signal field decodable by the second communication device;
Wherein the one or more integrated circuits are configured to include the legacy signal field in a first portion of the PHY preamble; And
Wherein 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
Generate an additional signal field conforming to the second communication protocol, and
And to include the additional signal field in a 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 second communication device. 14. The method of claim 13, wherein the one or more integrated circuits
And to include a replica of the additional signal field in a second portion of the PHY preamble. 12. The method of claim 11, wherein the one or more integrated circuits
And to include a replica of the additional signal field in a second portion of the PHY preamble. The method of claim 11,
The signal field is a first signal field; And
The one or more integrated circuits
Wherein the second signal field comprises information indicating a duration of the PHY data unit, the second signal field including information indicating a duration of the PHY data unit,
Including the second signal field in a first portion of the PHY preamble; And
And to include the first signal field in a second portion of the PHY preamble. 19. The first communication device of claim 17, wherein the second portion of the PHY preamble is not decodable to the second communication device. 12. The method of claim 11, wherein the one or more integrated circuits
Generating a PHY preamble for the PHY data unit by including an individual first guard interval between orthogonal frequency domain (OFDM) symbols in a first portion of the PHY preamble; And
Wherein the second guard interval is configured to generate the PHY payload that includes a respective second guard interval between OFDM symbols in the PHY payload, each second guard interval having a duration longer than a respective first guard interval, A first communication device. 21. The first communication device of claim 19, wherein the one or more integrated circuits are configured to generate the PHY preamble that includes an individual second guard interval between OFDM symbols in a second portion of the PHY preamble.

Images