JP2015534771A - Orthogonal frequency division multiplexing (OFDM) symbol format for wireless local area networks (WLANs) - Google Patents

Abstract

A plurality of information bits are encoded to generate a plurality of coded bits in an orthogonal frequency division multiplexing (OFDM) symbol generation method. Although the plurality of information bits corresponds to the first bandwidth, the OFDM symbol includes a number of data tones corresponding to the second bandwidth. The plurality of coded bits are mapped to a plurality of constellation symbols. The plurality of constellation symbols are mapped to the first plurality of data subcarriers corresponding to the first portion of the OFDM symbol and to the second plurality of data subcarriers corresponding to the second portion of the OFDM symbol. The subset of data subcarriers in the first plurality of data subcarriers and the second plurality of data subcarriers is set to one or more predetermined values. The OFDM symbol is then generated to include at least a first plurality of data subcarriers and a second plurality of data subcarriers.

Description

The present disclosure relates generally to multiple communication networks, and more specifically to communicating multiple functions of a device between multiple devices in a wireless network.
[Cross-reference to related applications]

  This application is named “VHTSIGB Modulation” and claims the benefit of US Provisional Application No. 61 / 360,828, filed July 1, 2010. The name of the invention is “Modulation of Signal Field in a "WLAN Frame Header", a continuation of US patent application Ser. No. 13 / 174,186, filed Jun. 30, 2011, the entire disclosures of which are hereby incorporated herein by reference. This application also claims the benefit of US Provisional Application No. 61 / 703,593, filed Sep. 20, 2012, entitled “VHTSIGB Modulation”, the entire disclosure of which is hereby incorporated herein by reference. Incorporated herein.

  The background description provided herein is generally intended to provide a context for the disclosure. The work of the inventors listed at present is clearly expressed in this disclosure within the scope described in this background chapter and within the scope of aspects of the description that may not be accepted as prior art at the time of filing. Neither implicitly nor implicitly recognized as prior art.

  The development of wireless local area network (WLAN) standards such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11a, 802.11b, 802.11g and 802.11n standards has improved the maximum data throughput for single users. . For example, the IEEE 802.11b standard specifies a single user maximum throughput of 11 megabits per second (Mbps), the IEEE 802.11a and 802.11g standards specify a single user maximum throughput of 54 Mbps, and the IEEE 802.11n standard specifies 600 Mbps. Specifies the single user maximum throughput for. Work begins on a new standard, IEEE 802.11ac, which is expected to provide even greater throughput.

  According to the first embodiment, a method for generating an orthogonal frequency division multiplexing (OFDM) symbol of a data unit transmitted over a communication channel encodes a plurality of information bits to be included in an OFDM symbol. Generating the coded bits of. The plurality of information bits corresponds to the first bandwidth, the OFDM symbol includes a number of data tones corresponding to the second bandwidth, and the second bandwidth is greater than the first bandwidth. The method also maps the plurality of coded bits to a plurality of constellation symbols, and maps the plurality of constellation symbols to a first plurality of data subcarriers corresponding to a first portion of the OFDM symbol. A stage of performing. The method further includes setting a subset of data subcarriers in the first plurality of data subcarriers to one or more predetermined values. Further, the method further includes mapping the plurality of constellation symbols to a second plurality of data subcarriers corresponding to the second portion of the OFDM symbol; and data subcarriers in the second plurality of data subcarriers. Setting the subset to one or more predetermined values. The method further includes generating an OFDM symbol to include at least a first plurality of data subcarriers and a second plurality of data subcarriers.

  In another embodiment, an apparatus comprises a network interface configured to encode a plurality of information bits to generate a plurality of coded bits to be included in an OFDM symbol. The plurality of information bits corresponds to the first bandwidth, the OFDM symbol includes a number of data tones corresponding to the second bandwidth, and the second bandwidth is greater than the first bandwidth. The network interface also maps the plurality of coded bits to a plurality of constellation symbols, and maps the plurality of constellation symbols to a first plurality of data subcarriers corresponding to the first portion of the OFDM symbol. It is configured as follows. The network interface is also configured to set a subset of data subcarriers in the first plurality of data subcarriers to one or more predetermined values. Furthermore, the network interface further maps the plurality of constellation symbols to a second plurality of data subcarriers corresponding to the second portion of the OFDM symbol, and a subset of data subcarriers in the second plurality of data subcarriers. Is configured to set to one or more predetermined values. The network interface is further configured to generate an OFDM symbol to include at least a plurality of data subcarriers corresponding to the first portion and a plurality of data subcarriers corresponding to the second portion.

1 is a block diagram of an exemplary embodiment of a wireless local area network (WLAN) that utilizes various signal field modulation and mapping techniques described herein. FIG.

It is a figure of the example data unit format which concerns on embodiment.

It is a block diagram of the example PHY processing unit which concerns on embodiment.

4 is a diagram of an exemplary OFDM symbol for a 40 MHz communication channel configured to be generated by the PHY processing unit of FIG. 3, according to an embodiment.

FIG. 4 is a diagram of another exemplary OFDM symbol for a 40 MHz communication channel configured to be generated by the PHY processing unit of FIG. 3, according to another embodiment.

4 is a diagram of an exemplary OFDM symbol for an 80 MHz communication channel configured to be generated by the PHY processing unit of FIG. 3, according to an embodiment.

FIG. 4 is a diagram of another exemplary OFDM symbol for an 80 MHz communication channel configured to be generated by the PHY processing unit of FIG. 3, according to another embodiment.

FIG. 3 is a flow diagram of an example method for generating and transmitting a PHY data unit with a signal field such as VHT-SIGB or another suitable field, according to an embodiment.

FIG. 6 is a flow diagram of another example method for generating and transmitting a PHY data unit with a signal field, such as VHT-SIGB or another suitable field, according to another embodiment.

FIG. 6 is a flow diagram of an example method for generating and transmitting a multi-user PHY data unit with a signal field, such as VHT-SIGB or another suitable field, according to an embodiment.

FIG. 3 is a flow diagram of an example method for generating an OFDM symbol, according to an embodiment.

  In embodiments described below, a wireless network device, such as a wireless local area network (WLAN) access point (AP), transmits multiple data streams to one or more client stations. In an embodiment, the AP is configured to operate with a plurality of client stations according to a first communication protocol (eg, IEEE 802.11ac standard). In embodiments, the different client stations proximate to the AP are further configured to operate according to a second communication protocol (eg, IEEE 802.11n standard, IEEE 802.11a standard, IEEE 802.11g standard, etc.). The first communication protocol and the second communication protocol define operation in a frequency band above 1 GHz and generally for multiple applications requiring relatively short range wireless communication at relatively low data rates. used. The first communication protocol is referred to herein as a very high throughput (VHT) protocol, and the second communication protocol is referred to herein as a legacy protocol. In some embodiments, the AP is further or alternatively configured to operate with multiple client stations according to a third communication protocol. A third communication protocol defines operation in the frequency band below 1 GHz and is typically used for multiple applications that require relatively long distance wireless communications at relatively low data rates. The first communication protocol and the second communication protocol are collectively referred to as a “short range” communication protocol, and the third communication protocol is referred to herein as a “long range” communication protocol.

  In an embodiment, each one of a plurality of communication protocols (eg, a plurality of short distance protocols, a plurality of long distance protocols) defines a plurality of transmission channel bandwidths. In some embodiments, the data unit transmitted or received by the AP includes a legacy portion corresponding to a bandwidth defined in the legacy protocol (eg, a 20 MHz bandwidth defined in the 802.11a protocol), and a VHT It includes a preamble with a VHT portion corresponding to the same or different channel bandwidth defined by the protocol (eg, 80 MHz bandwidth defined by the VHT protocol). According to an embodiment, the data unit preamble includes a plurality of signal fields that convey information required at the receiver to correctly identify and decode the data unit. In some embodiments, for example, the preamble includes two signal fields. The first signal field is included in the legacy portion of the preamble and modulated in a manner similar to the legacy portion of the data unit. The second signal field is included in the VHT portion of the preamble and is modulated in a manner similar to the VHT data portion of the data unit. In one such embodiment, the second signal field is modulated in a manner similar to the VHT data portion of the data unit, but uses a lower code rate and smaller constellation size than the VHT data portion. Further, in some embodiments, the bit allocation for the second signal field is the same regardless of the specific channel bandwidth occupied by the data unit. For example, in an embodiment, the bit allocation is specified for a minimum bandwidth defined by the VHT protocol (eg, 20 MHz bandwidth, 40 MHz, etc.) and transmits a second signal field in the higher VHT bandwidth. Bit insertion and / or duplication is used to do this. Further, in an embodiment, the VHT data portion of the data unit includes multiple spatial data streams directed to a single user (SU) or multi-user (MU), whereas the second signal field is a single Limited to data streams. In these embodiments, the single stream of the second signal field is mapped in several ways to multiple spatial streams and / or multiple users corresponding to the data portion of the data unit.

  FIG. 1 is a block diagram of an exemplary embodiment of a wireless local area network (WLAN) 10 that utilizes the various signal field modulation and mapping techniques described herein. The AP 14 includes a host processor 15 coupled to the network interface 16. The network interface 16 includes a medium access control (MAC) processing unit 18 and a physical layer (PHY) processing unit 20. The PHY processing unit 20 includes a plurality of transceivers 21 that are coupled to a plurality of antennas 24. Although three transceivers 21 and three antennas 24 are shown in FIG. 1, in other embodiments, the AP 14 has a different number (eg, 1, 2, 4, 5, etc.) of transceivers 21 and antennas 24. Can be included. In one embodiment, the MAC processing unit 18 and the PHY processing unit 20 are configured to operate according to a first communication protocol (eg, the IEEE 802.11ac standard currently in the process of being standardized). The first communication protocol is also referred to herein as a very high throughput (VHT) protocol. In another embodiment, the MAC processing unit 18 and the PHY processing unit 20 are also configured to operate according to at least a second communication protocol (eg, IEEE 802.11n standard, IEEE 802.11a standard, etc.). In yet another embodiment, the MAC processing unit 18 and the PHY processing unit 20 are further or alternatively configured to operate according to a long-range communication protocol (eg, IEEE 802.11ah standard, IEEE 802.11af standard, etc.).

  The WLAN 10 includes a plurality of client stations 25. Although four client stations 25 are shown in FIG. 1, in various scenarios and embodiments, the WLAN 10 may include a different number (eg, 1, 2, 3, 5, 6, etc.) of client stations 25. it can. At least one client station 25 (eg, client station 25-1) is configured to operate according to at least a first communication protocol.

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

  In the embodiment, one or all of the client stations 25-2, 25-3, and 25-4 have the same or similar structure as the client station 25-1. In these embodiments, multiple client stations 25 of the same or similar structure as client station 25-1 have the same or different number of transceivers and antennas. For example, in the embodiment, client station 25-2 has only two transceivers and two antennas.

  In various embodiments, the PHY processing unit 20 of the AP 14 is configured to generate a plurality of data units that conform to the first communication protocol. The one or more transceivers 21 are configured to transmit the generated plurality of data units via one or more antennas 24. Similarly, the one or more transceivers 24 are configured to receive a plurality of data units via one or more antennas 24. In an embodiment, the PHY processing unit 20 of the AP 14 is configured to process a plurality of data units that conform to the received first communication protocol.

  In various embodiments, the PHY processing unit 29 of the client device 25-1 is configured to generate a plurality of data units that conform to the first communication protocol. The one or more transceivers 30 are configured to transmit the generated plurality of data units via one or more antennas 34. Similarly, one or more transceivers 30 are configured to receive a plurality of data units via one or more antennas 34. In an embodiment, the PHY processing unit 29 of the client device 25-1 is configured to process a plurality of data units that conform to the received first communication protocol.

  FIG. 2 is a diagram of a data unit 250 configured for the AP 14 to transmit to the client station 25-1, according to an embodiment. In an embodiment, client station 25-1 is also configured to transmit data unit 250 to AP. The data unit 250 conforms to the VHT protocol and occupies the 80 MHz band. In other embodiments, data units similar to data unit 250 occupy different bandwidths, such as 20 MHz, 40 MHz, 120 MHz, 160 MHz or any suitable bandwidth. Further, the bands need not be contiguous in frequency, but may include two or more smaller bands separated within the frequency. For example, in embodiments, in some scenarios, such as when multiple situations and multiple devices support a 160 MHz channel, the data unit 250 is two consecutive, separated in frequency by some suitable minimum bandwidth. Do not occupy the 160MHz band consisting of 80MHz band. The data unit 250 includes four legacy short training fields (L-STF) 252, four legacy long training fields (L-LTF) 254, four legacy signal fields (L-SIG) 256, and four first verh throughput signal field (VHT-SIGA) 258, very high throughput short training field (VHT-STF) 262, N pieces of very high throughput long training field (VHT-LTF) 264, and a second very high throughput signal field ( VHT-SIGB) 268 Including the preamble it has. Here, N is an integer. Data unit 250 also includes a data portion 272. The plurality of L-STFs 252, the plurality of L-LTFs 254 and the plurality of L-SIGs 256 form a legacy part. The VHT-STF 262, the plurality of VHT-SIGAs 258, the plurality of VHT-LTF 264, the VHT-SIGB 268, and the data portion 266 form a very high throughput (VHT) part.

  In the embodiment of FIG. 2, each of the plurality of L-STFs 252, each of the plurality of L-LTFs 254, each of the plurality of L-SIGs 256, and each of the plurality of VHT-SIGAs 258 occupy a 20 MHz band. In this disclosure, several exemplary data units, including data unit 250, with a continuous bandwidth of 80 MHz are described for the purpose of representing multiple embodiments of multiple frame formats. However, these frame format embodiments and other embodiments are applicable to other suitable bandwidths (including non-contiguous bandwidths). For example, the preamble of FIG. 2 includes four each of L-STF 252, L-LTF 254, L-SIG 256, and VHT-SIGA 258, but orthogonal frequency division multiplexing (OFDM) data units are 20 MHz, 40 MHz, 120 MHz, and 160 MHz. In other embodiments that occupy a cumulative bandwidth other than 80 MHz, such as, etc., an appropriate number of L-STFs 252, L-LTF 254, L-SIG 256, and VHT-SIGA 258 are utilized depending on them. (For example, one L-STF 252, L-LTF 254, L-SIG 256, and VHT-SIGA 258 for an OFDM data unit occupying 20 MHz, and two for each of multiple fields for a 40 MHz bandwidth OFDM data unit. Each of the plurality of fields are 6 for OFDM data units 120MHz bandwidth, and each of the plurality of fields eight for OFDM data units 160MHz bandwidth). Also, in an OFDM data unit with a 160 MHz bandwidth, for example, in some embodiments and situations, the bands are not continuous in frequency. Thus, for example, L-STF 252, L-LTF 254, L-SIG 256, and VHT-SIGA 258 occupy two or more bands that are separated from each other in frequency. And in some embodiments, for example, consecutive bands are separated in frequency by at least 1 MHz, at least 5 MHz, at least 10 MHz, at least 20 MHz. In the embodiment of FIG. 2, each of VHT-STF 262, VHT-LTF 264, VHT-SIGB 268, and data portion 266 occupy the 80 MHz band. According to the embodiment, when the data unit conforming to the first communication protocol is an OFDM data unit that occupies the cumulative bandwidth of OFDM such as 20 MHz, 40 MHz, 120 MHz, or 160 MHz, the VHT-STF, the plurality of VHT-LTFs , VHT-SIGB, VHT data portion occupies the entire corresponding bandwidth of the data unit.

  Further, according to the embodiment of FIG. 2 in which the device generating the data unit 250 includes multiple antennas and can transmit beamforming or beam steering, the VHT-SIGA 258 is not steered of the data unit 250 ( That is, “omnidirectional” or “pseudo omnidirectional”; the terms “unsteered” and “omnidirectional” as used herein also encompass the term “pseudo omnidirectional”. PHY information that is common to each of the plurality of client stations 25 of FIG. In contrast, VHT-SIGB 268 is included in the “steered” part. In embodiments where the data unit 250 is a multi-user transmission (eg, including independent multiple data streams for different receiving devices to which the data unit 250 corresponds), the steered portion may be a plurality of client stations 25. Different data for different clients 25 transmitted simultaneously via multiple antennas 24 of FIG. 1 through different (or user-specific) multiple spatial channels to convey different content to each. Thus, in these embodiments, multiple VHT-SIGAs 258 convey common information to all users, whereas VHT-SIGB 268 includes user-specific information. In contrast, in embodiments where the data unit 250 is a single user transmission, the steered portion includes data for a particular client 25 that is transmitted to the client station 25 via the antenna 24 and beam steered.

  According to an embodiment, each of the plurality of VHT-SIGAs 258 comprises two OFDM symbols modulated in a similar manner to the legacy plurality of L-SIG fields 256. In contrast, according to some embodiments and / or scenarios below, the VHT-SIGB field 268 comprises a single OFDM symbol modulated in a manner similar to the VHT data portion 272.

  FIG. 3 is a block diagram of an example PHY processing unit 300 configured to generate OFDM symbols, according to an embodiment. For example, in embodiments and / or scenarios, the PHY processing unit 300 generates an OFDM symbol corresponding to the VHT-SIGB 268 of the data unit 250 (FIG. 2). In another embodiment and / or scenario, PHY processing unit 300 generates an OFDM symbol corresponding to data portion 272 of data unit 250. In other embodiments and / or scenarios, the PHY processing unit 300 may be an OFDM symbol corresponding to another portion of the data unit 250, or in other embodiments and / or scenarios. Generate OFDM symbols to be included in the appropriate data unit. In one embodiment, referring to FIG. 1, the AP 14 and the client station 25-1 each include a PHY processing unit, such as a PHY processing unit 300.

  According to an embodiment, the PHY unit 300 generally includes a forward error correction (FEC) encoder 302 that encodes an input data stream to generate a corresponding encoded stream. In one embodiment, the FEC encoder utilizes a code rate 1/2 binary convolutional code (BCC). In other embodiments, the FEC encoder may utilize other suitable multiple encoding formats and / or other suitable multiple code rates. The FEC encoder 302 interleaves multiple bits of the encoded stream to prevent a long sequence of adjacent noisy multiple bits from being input to the decoder at the receiver (ie, multiple bits of multiple bits). Connected to a frequency interleaver 304 (which changes the order).

The constellation mapper 306 maps the interleaved sequence of bits to a plurality of constellation points corresponding to different subcarriers of the OFDM symbol. More specifically, the constellation mapper 306 converts each log ₂ (M) into one of M constellation points. In one embodiment, constellation mapper 306 operates according to a binary phase shift keying (BPSK) modulation scheme. In other embodiments, other suitable modulation schemes are utilized. The constellation mapper 306 is coupled to a tone duplication and insertion unit 308 that implements various duplication and insertion techniques described below in various embodiments and / or scenarios.

  In an embodiment, the output of tone duplication and insertion unit 308 is provided to stream mapper unit 312. In an embodiment, the stream mapper 312 distributes multiple constellation points into more space-time streams. Pilot generation unit 310 generates a plurality of pilot tones used, for example, for frequency offset estimation at the receiver, and inserts the plurality of pilot tones into symbol OFDM tones at the plurality of space-time outputs of stream mapper 312. To do. Multiple cyclic shift diversity (CSD) units 314 insert multiple cyclic shifts into all space-time streams except one to prevent unintended beamforming.

  Spatial mapping unit 316 maps the multiple space-time streams to multiple transmission chains corresponding to one or more available transmit antennas. In various embodiments, the spatial mapping is: 1) multiple mapping constellation points from each space-time stream are directly mapped to multiple transmission chains (ie, one-to-one mapping) direct mapping, 2) all spatial -A spatial extension in which the vectors of constellation points from the time stream are expanded via matrix multiplication to generate multiple inputs to the multiple transmission chains; and 3) from all space-time streams Each vector of the plurality of constellation points is multiplied with a matrix of steering vectors to include one or more of the beamformings that generate the plurality of inputs to the plurality of transmit chains.

In one embodiment, the spatial mapping unit 316 applies a steering matrix Q (eg, multiplies a signal vector s of N _STS × 1 by Q, ie, Qs). Here, Q has a size of (N _TX × N _STS ), N _TX is the number of transmission chains, and N _STS is the number of space-time streams. When beamforming is utilized, the matrix Q is generated based on a multiple-input multiple-output (MIMO) channel between the transmitter and receiver. In one embodiment, N _TX has a maximum value of 8. In another embodiment, N _TX has a maximum value of 16. In other embodiments, N _TX has different maximum values, such as 4, 32, 64, etc.

  Each output of the spatial mapping unit 316 corresponds to a transmission chain, and each output of the spatial mapping unit 316 is processed by a discrete inverse Fourier transform (IDFT) unit 318 that converts a block of constellation points into a time domain signal. Is done. In an embodiment, the IDFT unit 318 is configured to implement a fast inverse Fourier transform (IFFT) algorithm. Each time domain signal is provided to a transmit antenna for transmission.

  According to an embodiment, the number of subcarriers (or tones) of an OFDM symbol generally depends on the channel bandwidth (BW) used. For example, according to an embodiment, an OFDM symbol for a 20 MHz channel corresponds to a size 64 IDFT and includes 64 tones. On the other hand, an OFDM symbol of a 40 MHz channel corresponds to a size 128 IDFT and includes 128 tones. In an embodiment, the multiple tones in the OFDM symbol include multiple guard tones for filtering up and down ramps, multiple DC tones for reducing radio frequency interference, and multiple tones for frequency offset estimation. Includes pilot tone. According to embodiments, the remaining multiple tones can be used to transmit data or multiple information bits (“multiple data tones”). Schematic transmitter flow of an exemplary PHY processing unit configured to generate data units compliant with a first communication protocol and utilized in multiple data units corresponding to some embodiments of the present disclosure Various examples of transmission channels and multiple tone mappings are described in US patent application Ser. No. 12 / 846,681 entitled “Methods and Apparatus for WLAN Transmission” filed Jul. 29, 2010. Which is incorporated herein by reference in its entirety.

  In an embodiment, the tones and / or bit assignments for OFDM symbols in a data unit are the same regardless of the channel bandwidth occupied by the data unit. For example, multiple OFDM symbols are generated according to a format defined for a “base” bandwidth, such as a minimum channel bandwidth defined by a communication protocol. The tone duplication and insertion techniques described herein are used to generate multiple OFDM symbols corresponding to wider multiple channel bandwidths. For example, in an embodiment, a 20 MHz channel bandwidth is used as the base bandwidth. In this embodiment, multiple OFDM symbols are generated according to the tone and / or bit allocation defined for the 20 MHz channel bandwidth, and the tone duplication and insertion techniques described herein are 40 MHz channels, 80 MHz channels. Etc. to generate a plurality of OFDM symbols corresponding to a plurality of higher bandwidth channels such as. In other embodiments, a bandwidth of 40 MHz is used as the base bandwidth, and multiple OFDM symbols with higher bandwidth are generated using the tone duplication and insertion techniques described herein. . In other embodiments, other suitable base bandwidths are utilized.

  In general, in various embodiments and / or scenarios, any suitable bandwidth corresponding to a size N IDFT can be utilized as the base bandwidth, and tone duplication and insertion described herein. The technique may be used to generate an OFDM symbol corresponding to a larger size IDFT, eg, a kN point IDFT, based on the tone and / or bit allocation defined for the N point IDFT. it can. Here, N and k are integers. It should be noted that tone duplication and insertion techniques are generally performed as described below to generate a wider bandwidth signal field based on tone and / or bit assignments defined for lower bandwidth signal fields. However, such techniques are not limited to multiple OFDM symbols corresponding to multiple signal fields, and in other embodiments, other fields of the OFDM data unit (eg, multiple training fields). Note that this applies to a plurality of OFDM symbols corresponding to the data field.

  As an example, referring again to FIG. 2, in an embodiment, the bit allocation for the VHT-SIGB field 268 of the data unit 250 is the same regardless of the channel bandwidth occupied by the particular data unit being generated. Also, in some embodiments, the same number of guard tones, DC tones and pilot tones are used in OFDM symbols generated for VHT-SIGB 268 as symbols generated for the data portion of data unit 250. Is done. In one such embodiment, multiple guard tones, multiple DC tones, and multiple pilot tones are included in the OFDM symbol generated for VHT-SIGB field 268 as an OFDM symbol generated for data portion 272. Of the same frequency.

  In an embodiment, the VHT-SIGB field 268 bit allocation corresponds to a 20 MHz OFDM symbol with a corresponding number of data tones for multiple data units corresponding to multiple larger bandwidths (eg, 40 MHz, 80 MHz, etc.). However, the same bit allocation is used. In one such embodiment, for example, 20 bits are assigned to the plurality of information bits, 6 bits are assigned to the plurality of tail bits, and 26 bits are assigned to the VHT-SIGB field. In an embodiment where the VHT-SIGB field 268 is encoded with a BCC encoder at a code rate of 1/2, 26 bits are encoded into 52 data bits corresponding to 52 data tones available on the 20 MHz channel. In other embodiments, other suitable bit assignments and other suitable encoding and modulation schemes are used for the VHT-SIGB field 268. To fill the remaining available data tones in various embodiments and / or scenarios where the same number of bits are assigned to multiple higher bandwidth channels with a corresponding higher number of data tones The tone duplication and insertion techniques described herein are utilized.

  FIG. 4 is a diagram of an OFDM symbol 400 generated for a VHT-SIGB field (such as the VHT-SIGB field 268 of FIG. 2) of a data unit for a 40 MHz channel, according to an embodiment. OFDM symbol 400 corresponds to an IDFT of size 128 and includes 128 tones. In an embodiment, 128 tone slots are indexed from -64 to +63. The 128 tones include guard tones, direct current (DC) tones, data tones and pilot tones. The six tones from the lowest frequency and the five tones from the highest frequency are the guard tones. Three tones indexed from -1 to +1 are DC tones. In an embodiment, OFDM symbol 400 also includes 6 pilot tones and 108 data tones. As shown in FIG. 4, the 108 data tones include 52 tones corresponding to VHT-SIGB bits with 2 insertion tones, and the resulting 54 tones represent the remaining tones of the OFDM symbol. Duplicated once more to fill. In OFDM symbol 400, the two insertion tones occupy the lowest data / pilot frequency tone slot in the lower channel sideband and the two lowest data / pilot frequency tone slots in the higher channel sideband. .

  FIG. 5 is a diagram of another exemplary OFDM symbol 500 generated for a VHT-SIGB field (eg, VHT-SIGB field 268 of FIG. 2) of a data unit for a 40 MHz channel, according to another embodiment. is there. OFDM symbol 500 includes a plurality of insertion tones in OFDM symbol 500 with two lowest data / pilot frequency tone slots in the lower channel sideband and two highest data / pilot frequency tone slots in the higher channel sideband. Is the same as the OFDM symbol 400 except that it occupies.

  In another embodiment, the two insertion tones occupy any other suitable plurality of data / pilot frequency tone slots in OFDM symbol 400 or OFDM symbol 500.

  FIG. 6 is a diagram of an OFDM symbol 600 generated for a VHT-SIGB field (eg, VHT-SIGB field 268 of FIG. 2) of a data unit for an 80 MHz channel, according to an embodiment. OFDM symbol 600 corresponds to a size 256 IDFT and includes 256 tones. In an embodiment, 256 tone slots are indexed from -128 to +127. The 256 tones include a plurality of guard tones, a plurality of DC tones, a plurality of data tones, and a plurality of pilot tones. The six tones from the lowest frequency and the five tones from the highest frequency are the guard tones. Three tones indexed from -1 to +1 are DC tones. The OFDM symbol 350 also includes 8 pilot tones and 234 data tones. The 234 data tones include 52 tones corresponding to multiple VHT-SIGB information bits, 52 tones that are duplicates of multiple VHT-SIGB information bits, and 13 inserted tones, and the resulting 117 tones Is replicated once. In OFDM symbol 600, the 13 insertion tones are the lowest frequency pilot / data tone slots in the lower channel sideband and the lowest frequency pilot / data tone slots in the higher channel sideband. Occupy.

  FIG. 7 is a block diagram of another OFDM symbol 700 generated for a VHT-SIGB field (eg, VHT-SIGB field 268 of FIG. 2) of a data unit for an 80 MHz channel, according to another embodiment. . OFDM symbol 700 includes 13 lowest frequency data / pilot tone slots in lower channel sidebands and highest frequency data / pilot tones in higher channel sidebands in OFDM symbol 700. Similar to OFDM symbol 600, except that it occupies a slot.

  In another embodiment, the 13 insertion tones occupy other suitable data / pilot tone slots in OFDM symbol 600 or OFDM symbol 700.

  In an embodiment or situation, multiple insertion tones in symbol 400, multiple insertion tones in symbol 500, multiple insertion tones in symbol 600 and / or multiple insertion tones in symbol 700 may be VHT-SIGB information bits. And / or carry some value of the VHT-SIGA information bits. Similarly, in some other embodiments and / or situations, multiple insert tones in symbol 400, multiple insert tones in symbol 500, multiple insert tones in symbol 600 and / or multiple in symbol 700. The inserted tone carries several values of the LSIG information bits. Alternatively, in other embodiments and / or situations, multiple insertion tones in symbol 400, multiple insertion tones in symbol 500, multiple insertion tones in symbol 600 and / or multiples in symbol 700. The insertion tones are a plurality of null (0) tones. These embodiments have the advantage of not using additional transmit power to transmit multiple insertion tones (ie, all of the total transmit power is due to VHT-SIGB information and tail bits). Used). In other embodiments and / or scenarios, multiple insertion tones in symbol 400, multiple insertion tones in symbol 500, multiple insertion tones in symbol 600, multiple insertion tones in symbol 700 are arbitrary Is modulated with other suitable values.

  In other embodiments and / or scenarios, multiple insertion tones in symbol 400, multiple insertion tones in symbol 500, multiple insertion tones in symbol 600 and / or multiple insertion tones in symbol 700 are , Modulated with any other suitable values.

  In an embodiment, client station 25-1 of FIG. 1 discards multiple inserted tones in the VHT-SIGB field of the received data unit during the decoding and demodulation process. Alternatively, in an embodiment, if the multiple insertion tones are of multiple values corresponding to several information bits of a signal field (eg, VHT-SIGA, VHT-SIGB, L-SIG), the receiver Rather than simply discarding multiple inserted tones, it takes advantage of the additional diversity provided by them during the decoding and demodulation process.

  In some embodiments, the 80 MHz signal field is generated using a tone and / or bit allocation for a 40 MHz bandwidth as the base bandwidth. For example, in an embodiment, the 80 MHz VHT-SIGB field should fill the remaining data tones of the 80 MHz VHT-SIGB field using the tones and / or bit assignments defined for the 40 MHz VHT-SIGB field. It is generated using the tone duplication and insertion techniques described herein. Similarly, in an embodiment, the 160 MHz signal field uses tone and / or bit assignments for the 80 MHz signal field to fill the remaining data tones of the 160 MHz field as described herein. And using insertion techniques. In another embodiment, the 160 MHz MHz field is generated using the tone insertion and duplication techniques described herein, using the tone and / or bit assignments for the 40 MHz bandwidth signal field. In overview, in various embodiments and / or scenarios, the base bandwidth B is utilized to generate OFDM symbols for an mB bandwidth communication channel. Here, m is an integer.

  In an embodiment, a field corresponding to 20 MHz or another suitable bandwidth is utilized to generate a larger base bandwidth, such as a 40 MHz base bandwidth. For example, one or more uncoded bits can be transferred to a 20 MHz bandwidth channel or another suitable bandwidth channel so that the encoded bitstream corresponds to a larger bandwidth such as a 40 MHz bandwidth after encoding. Inserted into the corresponding bitstream. A tone duplication and insertion technique is then applied to the base bandwidth to generate multiple OFDM symbols for multiple higher bandwidth channels. For example, referring to FIG. 3, a copy of a plurality of uncoded information bits is utilized, and the resulting bitstream (encoded bits) after being encoded by encoder 302 is 40 MHz base bandwidth, etc. If necessary, one or more additional bits may be added to the uncoded information bitstream (eg, multiple bit replicas) before feeding the bitstream to the encoder 302 to accommodate a wider base bandwidth. Added before or after multiple bit duplication occurs. In this embodiment, the coded bits then constellation that maps the coded bits to constellation points corresponding to OFDM tones with a base bandwidth, such as a 40 MHz bandwidth. Provided to the mapping unit 306. In an embodiment, tone duplication and insertion unit 308 then duplicates and / or duplicates the resulting multiple OFDM tones, for example, to generate a wider bandwidth OFDM symbol, such as an 80 MHz OFDM symbol or a 160 MHz OFDM symbol. Or, additional multiple OFDM tones are inserted.

  As described above, in some embodiments, the AP 14 is configured to communicate with one or more client stations according to a long-range communication protocol that defines operation in a frequency band generally below 1 GHz. In some such embodiments, the long range communication protocol uses one or more physical layer data unit formats that are the same as or similar to the physical layer data unit format defined by the one or more short range communication protocols. Define. In one embodiment, long distance to support communication over longer distances and to accommodate multiple channels of typically lower bandwidth available at lower (below 1 GHz) frequencies. The communication protocol defines a plurality of data units that are substantially the same as the physical layer data unit format defined by the long-range communication protocol, but with a format that is generated using a lower clock rate. In an embodiment, the AP operates at a clock rate suitable for short range (and high throughput) operation and a down clock is used to generate a new clock signal that is used for operation below 1 GHz. The As a result, in this embodiment, a data unit that conforms to a long-range communication protocol (“long-range data unit”) is generally a physical layer format of a data unit that conforms to a short-range communication protocol (“short-range data unit”). Is transmitted over a longer period of time. As an example, multiple data units conforming to the IEEE 802.11ah standard are generated according to the format defined in the IEEE 802-11n standard or the IEEE 802-11ac standard, but generated using a clock signal downclocked by a ratio of 10 Is done. In this embodiment, the multiple short range data units generally correspond to the multiple channel bandwidths described above (eg, 20 MHz, 40 MHz, 80 MHz, 160 MHz), and the multiple long range data units have a down clock ratio of 10. Corresponding multiple down-clocked bandwidths (eg, 2 MHz, 4 MHz, 8 MHz, 16 MHz).

  In other embodiments, other suitable downclock ratios are utilized. For example, in an embodiment, the plurality of data units according to IEEE 802.11af are a plurality of versions down-clocked with a down clock ratio 7.5 of the data units of IEEE 802.11n or IEEE 802.11ac. Further, in some embodiments, the long-range communication protocol may be, for example, a 1 MHz bandwidth channel intended for multiple operations that require higher signal-to-noise ratio performance such as extended range or control mode operation. Define one or more additional bandwidth channels. Various examples of long-range data units generated by a downclock and exemplary multiple PHY formats of long-range data units utilized in some embodiments are disclosed in the United States application filed Jan. 26, 2012. Patent application 13 / 359,336 is incorporated herein by reference in its entirety.

  In some such embodiments, the lowest channel bandwidth that is down-clocked is utilized as the base bandwidth, and the tone duplication and insertion techniques described herein accommodate higher channel bandwidths. Used to generate multiple OFDM symbols. For example, tones and / or bit assignments defined for multiple OFDM symbols corresponding to 1 MHz base bandwidth or 2 MHz base bandwidth to generate multiple OFDM symbols corresponding to multiple higher bandwidths The tone duplication and insertion techniques utilized and described herein are utilized to generate multiple OFDM symbols for multiple higher bandwidth channels (eg, 2 MHz, 4 MHz, 8 MHz, 16 MHz). By way of example, in various embodiments and referring to FIGS. 4 and 5, the depicted OFDM symbols 400 and 500 are long distances generated using tone assignments defined for a 2 MHz bandwidth channel. Corresponds to the 4 MHz bandwidth of the communication protocol. As another example, in various embodiments and referring to FIGS. 6 and 7, the depicted OFDM symbols 600 and 700 were generated using tone assignments defined for a 2 MHz bandwidth channel. Corresponds to the 8 MHz bandwidth of the long-range communication protocol. In another embodiment, tone and / or bit allocation for another suitable base bandwidth, such as 4 MHz bandwidth, is utilized, and the tone duplication and insertion techniques described herein can be used for 8 MHz or 16 MHz channels, etc. Used to generate multiple OFDM symbols corresponding to higher bandwidth channels. In overview, in various embodiments and / or scenarios, the base bandwidth B is utilized to generate OFDM symbols for an mB bandwidth communication channel. Here, m is an integer.

に従ってマッピングされる。ここで、Ｑ^（ｋ）は、ＶＨＴ−ＬＴＦトレーニングフィールドのｋ番目のトーンの空間マッピングに対応し、Ｄ^（ｋ）は、ｋ番目のトーンのＣＳＤ位相シフトに対応し、Ｐ_＊１，...，Ｐ_{＊ＮＬＴＦ}は、マッピング行列Ｐの複数の列であり、Ｓ^（ｋ）は、ＶＨＴ−ＬＴＦトレーニングシンボルのｋ番目のトーンである。 Referring again to FIG. 2, in embodiments where the data portion 272 includes multiple spatial streams, the VHT-SIGB field 268 is mapped to multiple streams accordingly. In some such embodiments, the VHT-STF field 264 that includes multiple training sequences corresponding to multiple spatial streams is mapped to multiple spatial streams via a matrix P. In some embodiments and / or scenarios, the same matrix P maps a single data stream in the VHT-SIGB field 268 to multiple data streams corresponding to multiple spatial streams in the VHT-data portion 272. Used for. More specifically, in an embodiment, the plurality of VHT-LTF training fields 264 are associated with a plurality of corresponding spatial streams.

Is mapped according to Where Q ^(k) corresponds to the spatial mapping of the kth tone in the VHT-LTF training field, D ^(k) corresponds to the CSD phase shift of the kth tone, P _{* 1} ,. ., P _{* NLTF} is a plurality of columns of the mapping matrix P, and S ^(k) is the kth tone of the VHT-LTF training symbol.

ここで、Ｓ_{ＶＨＴＳＩＧＢ＿Ｕ１} ^（ｋ）は、ＶＨＴ−ＳＩＧＢシンボルのｋ番目のトーンである。他の複数の実施形態及び／又はシナリオでは、Ｐ行列の異なる列が、ＶＨＴ−ＳＩＧＢフィールド２６８をマッピングするために使用される。 Still referring to FIG. 2, in an embodiment, the VHT-SIGB field 268 uses one of the plurality of columns P _{* 1} ,..., P _{* NLTF} of _Equation 1 to Mapped to multiple spatial streams. For example, in an embodiment, the first column of the P matrix is used to map the VHT-SIGB field 268.

Here, S _{VHTSIGB_U1} ^(k) is the k-th tone of the VHT-SIGB symbol. In other embodiments and / or scenarios, different columns of the P matrix are used to map the VHT-SIGB field 268.

に従ってマッピングされる。ここで、Ｑ_Ｕ１ ^（ｋ）は、ユーザ１のＶＨＴ−ＬＴＦトレーニングフィールドのｋ番目のトーンの空間マッピングに対応し、Ｑ_Ｕ２ ^（ｋ）は、ユーザ２のＶＨＴ−ＬＴＦトレーニングフィールドのｋ番目のトーンの空間マッピングに対応し、Ｄ_Ｕ１ ^（ｋ）は、ユーザ１に対するｋ番目のトーンの巡回シフトダイバーシチ（ＣＳＤ）位相シフトに対応し、Ｄ_Ｕ２ ^（ｋ）は、ユーザ２に対するｋ番目のトーンの巡回シフトダイバーシチ（ＣＳＤ）位相シフトに対応し、Ｐ_{（Ｕ１）＿＊１}，...，Ｐ_{（Ｕ１）＿＊ＮＬＴＦ}は、ユーザ１に対するマッピング行列Ｐの複数の列であり、Ｐ_{（Ｕ２）＿＊１}，...，Ｐ_{（Ｕ２）＿＊ＮＬＴＦ}は、ユーザ２に対するマッピング行列Ｐの複数の列であり、Ｓ^（ｋ）は、ＶＨＴ−ＬＴＦトレーニングシンボルのｋ番目のトーンである。 In some embodiments, the data unit 250 is a multi-user (MU) data unit, ie, the data unit 250 is more than one user (eg, from one of the plurality of client stations 25 of FIG. 1). User-specific information about many client stations). For example, in an embodiment, the data unit 250 includes user specific information for two users (ie, the data unit 250 is a “two user” data unit). In other embodiments and / or scenarios, the data unit 250 includes data for different numbers of users (eg, 3 users, 4 users, 5 users, etc.). In some embodiments, the number of VHT-LTF fields 264 is directly related to the sum of the spatial streams for all of the intended recipients (users) of the data unit. A single “giant” mapping matrix P is then used to map together multiple training information tones for all users and all spatial streams. For example, in an embodiment, if the data unit 250 is a two user data unit, the VHT-LTF field 268 is

Is mapped according to Where Q _U1 ^(k) corresponds to the spatial mapping of the k th tone of user 1's VHT-LTF training field, and Q _U2 ^(k) is the k th tone of user 2's VHT-LTF training field. , D _U1 ^(k) corresponds to the cyclic shift diversity (CSD) phase shift of the k th tone for user 1, and D _U2 ^(k) is the cyclic of the k th tone for user 2. Corresponding to shift diversity (CSD) phase shift, P _{(U1) _ * 1} ,..., P _{(U1) _ * NLTF} are a plurality of columns of the mapping matrix P for user 1, and P _{(U2) _ * 1, ..., P (U2} ) _ * NLTF are a plurality of columns of the mapping matrix P with respect to the user ^{2, S (k)} is, VHT-LTF training symbol Which is the k-th tone.

に従ってＶＨＴ−ＳＩＧＢフィールド２６８をユーザ１にマッピングするために結合Ｐ行列の第１の列が使用される。ここで、Ｓ_{ＶＨＴＳＩＧＢ＿Ｕ１} ^（ｋ）は、ユーザ１に対するＶＨＴ−ＳＩＧＢシンボルのｋ番目のトーンである。他の複数の実施形態では、結合Ｐ行列の別の複数の列が、ＶＨＴ−ＳＩＧＢフィールド２６８を、複数のデータストリームを介して対象とするユーザにステアリングするために使用される。 With continued reference to FIG. 2, in an embodiment where the data unit 250 is a two-user data unit, the VHT-SIGB field 268 is therefore steered towards two users (each user from another user). Assume that no interference is observed). In this case, a single stream in the VHT-SIGB field 268 is an arbitrary sequence P _{(U1) _ * 1} ,..., P _{(U1) _ * NLTF} or P _{(U2) _ * 1 ,.} .., P _{(U2) _ * NLTF} is used to map to multiple spatial streams and multiple users. For example, in the embodiment:

The first column of the combined P matrix is used to map the VHT-SIGB field 268 to user 1 according to Here, S _{VHTSIGB_U1} ^(k) is the k-th tone of the VHT-SIGB symbol for user 1. In other embodiments, other columns of the combined P matrix are used to steer the VHT-SIGB field 268 to the intended user via multiple data streams.

  FIG. 8 is a flow diagram illustrating an example method 800 for generation and transmission of a PHY data unit with a signal field, such as VHT-SIGB or another suitable field, according to an embodiment. Method 800 is at least partially implemented by a PHY processing unit, such as PHY processing unit 20 (FIG. 1), PHY processing unit 29 (FIG. 1), and / or PHY processing unit 300 (FIG. 3). FIG. 8 is described with reference to FIG. 3 for ease of explanation. However, in other embodiments, another suitable PHY processing unit and / or network interface implements the method 800.

  At block 804, a signal field of the preamble of the PHY data unit is generated. In an embodiment, a VHT-SIGB field is generated. In another embodiment, another suitable signal field is generated.

  At block 808, the signal field generated at block 804 is mapped to a first plurality of data subcarriers corresponding to the first frequency portion of the OFDM symbol. For example, the BPSK constellation mapping block 306 maps the signal field to a first plurality of data subcarriers corresponding to the first frequency portion of the OFDM symbol. In another embodiment, another suitable processing block of the network interface implements block 808.

  At block 812, the set of data subcarriers in the first plurality of data subcarriers is set to a plurality of predetermined values. For example, in an embodiment, at least some of the subcarriers in the set of subcarriers are set to the value “+1” or other suitable value. In another example, in an embodiment, at least some of the subcarriers in the set of subcarriers are set to the value “−1” or other suitable value. As another example, in an embodiment, at least some of the subcarriers in the set of subcarriers are set to a null value. In an embodiment, block 812 is implemented by tone duplication and insertion block 308 of FIG. In another embodiment, another suitable processing block of the network interface implements block 812.

  At block 816, the signal field generated at block 804 is mapped to a second plurality of data subcarriers corresponding to the second frequency portion of the OFDM symbol. For example, tone duplication and insertion block 308 in FIG. 3 maps the signal field to a second plurality of data subcarriers corresponding to the second frequency portion of the OFDM symbol. In another embodiment, another suitable processing block of the network interface implements block 816.

  At block 820, a set of data subcarriers in the second plurality of data subcarriers is set to a plurality of predetermined values. For example, in an embodiment, at least some of the subcarriers in the set of subcarriers are set to the value “+1” or some other suitable value. In another example, in an embodiment, at least some of the subcarriers in the set of subcarriers are set to the value “−1” or some other suitable value. As another example, in an embodiment, at least some of the subcarriers in the set of subcarriers are set to a null value. In an embodiment, block 820 is implemented by tone duplication and insertion block 308 of FIG. In another embodiment, another suitable processing block of the network interface implements block 820.

  At block 824, a plurality of guard tones, a plurality of DC tones and / or a plurality of pilot tones in the first frequency portion and the second frequency portion are set. In an embodiment, block 824 is at least partially implemented by VHT pilot generation block 310. In another embodiment, another suitable processing block of the network interface implements block 824.

  At block 828, the PHY data unit is transmitted. For example, in an embodiment, a PHY processing unit that implements the method 800 causes at least partially transmission of a PHY data unit.

  FIG. 9 is a flow diagram of another example method 900 for generation and transmission of a PHY data unit having a signal field, such as VHT-SIGB or another suitable field, according to an embodiment. Method 900 is implemented at least in part by a PHY processing unit, such as PHY processing unit 20 (FIG. 1), PHY processing unit 29 (FIG. 1), and / or PHY processing unit 300 (FIG. 3), and FIG. Will be described with reference to FIG. However, in other embodiments, another suitable PHY processing unit and / or network interface implements the method 900.

  At block 904, a plurality of training fields are generated. For example, in an embodiment, multiple VHT-LTF fields are generated in the embodiment. At block 908, multiple training fields are mapped to multiple signal streams using a mapping matrix. In the embodiment, the mapping matrix includes the matrix P described above. In other embodiments, other suitable mapping matrices are used. In an embodiment, block 908 is implemented by mapping block 312. However, in other embodiments, another suitable block of the PHY processing unit and / or network interface implements block 908.

  At block 912, a signal field of the preamble of the PHY data unit is generated. In an embodiment, a VHT-SIGB field is generated. In another embodiment, another suitable signal field is generated. At block 916, the signal field is mapped to multiple signal streams using the columns of the mapping matrix utilized at block 908. In the embodiment, the columns of the matrix P described above are used. In other embodiments, another suitable mapping matrix column is used. In an embodiment, the first column of the matrix P is used. In other embodiments, columns other than the first column of the matrix P are used.

  At block 920, multiple signal streams are mapped to multiple spatial streams. In an embodiment, the multiple signal streams are mapped to multiple spatial streams using the matrix Q described above. In other embodiments, other suitable matrices are utilized. In an embodiment, block 920 is implemented by spatial mapping block 316. However, in other embodiments, another suitable block of the PHY processing unit and / or network interface implements block 920.

  At block 924, the PHY data unit is transmitted. For example, in an embodiment, a PHY processing unit implementing method 900 causes at least partially transmission of a PHY data unit. Block 924 includes transmitting (or causing) to transmit at least i) a plurality of training fields and ii) signal fields via the plurality of spatial streams.

  FIG. 10 is a flow diagram of another example method 950 for generating and transmitting a multi-user PHY data unit having a signal field, such as VHT-SIGB or another suitable field, according to an embodiment. Method 950 is implemented at least in part by a PHY processing unit, such as PHY processing unit 20 (FIG. 1), PHY processing unit 29 (FIG. 1), and / or PHY processing unit 300 (FIG. 3), and FIG. Will be described with reference to FIG. However, in other embodiments, another suitable PHY processing unit and / or network interface implements the method 950.

  At block 954, multiple training fields are generated for the multi-user PHY data unit. For example, in the embodiment, a plurality of VHT-LTF fields are generated. At block 958, multiple training fields are mapped to multiple signal streams using a mapping matrix. In the embodiment, the mapping matrix includes the large matrix P described above. In other embodiments, other suitable mapping matrices are utilized. In an embodiment, block 958 is implemented by mapping block 312. However, in other embodiments, another suitable block of the PHY processing unit and / or network interface implements block 958.

  At block 962, a first signal field of a multi-user PHY data unit preamble is generated, the first signal field corresponding to a first client device. In an embodiment, a VHT-SIGB field is generated. In another embodiment, another suitable signal field is generated. At block 966, the first signal field is mapped to multiple signal streams using a portion of the mapping matrix column used at block 958. Here, the part corresponds to the first client device. In the embodiment, some of the columns of the large matrix P described above are used. Here, the part corresponds to the first client device. In other embodiments, some of the columns of another suitable mapping matrix are utilized. In the embodiment, a part of the first column of the large matrix P is used. In other embodiments, a part of the columns other than the first column of the large matrix P is used.

  At block 970, a second signal field of the multi-user PHY data unit preamble is generated, the second signal field corresponding to the second client device. In an embodiment, a VHT-SIGB field is generated. In another embodiment, another suitable signal field is generated. At block 974, the second signal field is mapped to multiple signal streams using a portion of the mapping matrix column utilized at block 958. Here, the part corresponds to the second client device. In the embodiment, some of the columns of the large matrix P described above are used. Here, the part corresponds to the second client device. In other embodiments, a portion of another suitable mapping matrix column is utilized. In the embodiment, a part of the first column of the large matrix P is used. In other embodiments, some of the columns of the large matrix P other than the first column are used. In an embodiment, the same column is used in blocks 966 and 974.

  At block 978, the multiple signal streams are mapped to the spatial stream. In an embodiment, multiple signal streams are mapped to multiple spatial streams using the matrix Q described above. In other embodiments, other suitable matrices are utilized. In an embodiment, block 978 is implemented by a spatial mapping block 316. However, in other embodiments, another suitable block of the PHY processing unit and / or network interface implements block 978.

  At block 982, a multi-user PHY data unit is transmitted. For example, in an embodiment, a PHY processing unit that implements the method 950 causes at least partially a PHY data unit to be transmitted. Block 982 includes transmitting (or causing to transmit) at least i) a plurality of training fields, ii) a first signal field, and iii) a second signal field via a plurality of spatial streams.

  FIG. 11 is a flow diagram of an example method 1000 for generating OFDM symbols for PHY data units, according to an embodiment. Method 1000 is at least partially implemented by a PHY processing unit, such as PHY processing unit 20 (FIG. 1), PHY processing unit 29 (FIG. 1), and / or PHY processing unit 300 (FIG. 3), in some embodiments. Is done. In other embodiments, other suitable PHY processing units and / or network interfaces implement method 1000.

  In block 1002, a plurality of information bits are encoded to generate a plurality of coded information bits to be included in the OFDM symbol. The plurality of information bits corresponds to the first bandwidth, and the OFDM symbol includes a number of data subcarriers corresponding to the second bandwidth. Here, the second bandwidth is larger than the first bandwidth. For example, in various embodiments and / or scenarios, the plurality of information bits may be a base channel such as a 1 MHz bandwidth, a 2 MHz bandwidth, a 4 MHz bandwidth, a 20 MHz bandwidth, a 40 MHz bandwidth, or another suitable base channel bandwidth. Corresponding to bandwidth B, the OFDM symbol includes several data tones that are larger than the base bandwidth, eg corresponding to the channel bandwidth of the mB bandwidth channel. Where m is a suitable integer greater than 1.

  At block 1004, the plurality of coded bits are mapped to a plurality of constellation symbols. At block 1006, the plurality of constellation symbols are mapped to a first plurality of data subcarriers corresponding to the first frequency portion of the OFDM symbol.

  At block 1008, the set of one or more data subcarriers in the first plurality of data subcarriers is set to a plurality of predetermined values. For example, in an embodiment, at least some of the subcarriers in the set of subcarriers are set to the value “+1” or some other suitable value. As another example, in embodiments, at least some of the subcarriers in the set of subcarriers are set to the value “−1” or some other suitable value. As another example, in an embodiment, at least some of the subcarriers in the set of subcarriers are set to a null value. In an embodiment, block 1006 is implemented by tone duplication and insertion block 308 of FIG. In another embodiment, another suitable processing block of the network interface implements block 1006.

  At block 1010, the plurality of constellation symbols are mapped to a second plurality of data subcarriers corresponding to a second frequency portion of the OFDM symbol. For example, tone duplication and insertion block 308 of FIG. 3 maps the signal field to a second plurality of data subcarriers corresponding to the second frequency portion of the OFDM symbol. In another embodiment, another suitable processing block of the network interface implements block 1010.

  At block 1012, a set of one or more data subcarriers in the second plurality of data subcarriers is set to a plurality of predetermined values. For example, in an embodiment, at least some subcarriers in the set of subcarriers are set to the value “+1” or some other suitable value. As another example, in embodiments, at least some subcarriers in the set of subcarriers are set to the value “−1” or some other suitable value. As another example, in an embodiment, at least some subcarriers in the set of subcarriers are set to a null value. In an embodiment, block 1012 is implemented by tone duplication and insertion block 308 of FIG. In another embodiment, another suitable processing block of the network interface implements block 1012.

  At block 1014, an OFDM symbol is generated to include at least a first plurality of data subcarriers and a second plurality of data subcarriers. In an embodiment, the OFDM symbol is generated to further include one or more of (i) multiple guard tones, (ii) multiple DC tones, and (iii) multiple pilot tones. In an embodiment, the OFDM symbol conforms to a format defined by a short-range communication protocol such as, for example, the IEEE 802.11n standard or the IEEE 802.11ac standard. In another embodiment, the OFDM symbol is compliant with a communication protocol such as the IEEE 802.11ah standard or the IEEE 802.11af standard, and is down-clocked (eg, with some tones and / or OFDM symbols compliant with a short-range communication protocol). (Or with bit allocation). In other embodiments, the OFDM symbols are compliant with other suitable communication protocol or protocols.

  In an embodiment, the OFDM symbol will be included in the preamble of the data unit. For example, in some embodiments and / or scenarios, an OFDM symbol corresponds to a signal field or training field that will be included in the preamble. In other embodiments and / or scenarios, the OFDM symbol will be included in the data portion of the data unit.

  At least some of the various blocks, operations and techniques described above may be implemented utilizing hardware, a processor executing multiple firmware instructions, a processor executing multiple software instructions, or any combination thereof. When implemented using a processor that executes multiple software or firmware instructions, the multiple software or firmware instructions may be a magnetic disk, optical disk, RAM, ROM, flash memory, hard disk drive, optical disk drive, tape drive, etc. Any tangible and non-tangible computer readable storage media or multiple media may be stored. The plurality of software or firmware instructions may include a plurality of machine readable instructions that, when executed by one or more processors, cause the one or more processors to perform various operations.

  If implemented in hardware, the hardware may comprise one or more separate components, integrated circuits, application specific integrated circuits (ASICs), programmable logic devices, and the like.

  According to the first embodiment, a method for generating an orthogonal frequency division multiplexing (OFDM) symbol of a data unit transmitted over a communication channel encodes a plurality of information bits to be included in an OFDM symbol. Generating the coded bits of. The plurality of information bits corresponds to the first bandwidth, the OFDM symbol includes a number of data tones corresponding to the second bandwidth, and the second bandwidth is greater than the first bandwidth. The method also maps the plurality of coded bits to a plurality of constellation symbols, and maps the plurality of constellation symbols to a first plurality of data subcarriers corresponding to a first portion of the OFDM symbol. A stage of performing. The method further includes setting a subset of data subcarriers in the first plurality of data subcarriers to one or more predetermined values. Further, the method further comprises: mapping the plurality of constellation symbols to a second plurality of data subcarriers corresponding to the second portion of the OFDM symbol; and data subcarriers in the second plurality of data subcarriers Setting a subset of to one or more predetermined values. The method further includes generating an OFDM symbol to include at least a first plurality of data subcarriers and a second plurality of data subcarriers.

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

  Setting the subset of data subcarriers in the first plurality of data subcarriers to one or more predetermined values comprises at least one piece of data in the subset of data subcarriers in the first plurality of data subcarriers. Setting a subcarrier to a null value.

  Setting the subset of data subcarriers in the second plurality of data subcarriers to one or more predetermined values comprises at least one data in the subset of data subcarriers in the second plurality of data subcarriers. Setting a subcarrier to a null value.

  Setting the subset of data subcarriers in the first plurality of data subcarriers to one or more predetermined values comprises at least one piece of data in the subset of data subcarriers in the first plurality of data subcarriers. Setting the subcarrier to a non-zero value.

  Setting the subset of data subcarriers in the second plurality of data subcarriers to one or more predetermined values comprises at least one data in the subset of data subcarriers in the second plurality of data subcarriers. Setting the subcarrier to a non-zero value.

  The method maps a plurality of constellation symbols to a third plurality of data subcarriers corresponding to a third portion of the OFDM symbol, and 1 sets a subset of data subcarriers in the third plurality of data subcarriers. And setting to one or more predetermined values.

  Generating the OFDM symbol further comprises including a third plurality of data subcarriers in the OFDM symbol.

  The method further comprises generating a physical layer (PHY) data unit preamble, the preamble including an OFDM symbol.

  The method further comprises generating a data portion of a physical layer (PHY) data unit, the data portion including an OFDM symbol.

  Before encoding a plurality of information bits, the method includes: (ii) inserting one or more additional bits into the plurality of information bits; and (ii) duplicating the plurality of information bits and the additional bits. Generating a plurality of bits, and encoding the plurality of information bits comprises encoding a plurality of replicated bits.

  The first bandwidth corresponds to bandwidth B, the second bandwidth corresponds to bandwidth mB, and m is an integer.

  In another embodiment, an apparatus comprises a network interface configured to encode a plurality of information bits to generate a plurality of coded bits to be included in an OFDM symbol. The plurality of information bits corresponds to the first bandwidth, the OFDM symbol includes a number of data tones corresponding to the second bandwidth, and the second bandwidth is greater than the first bandwidth. The network interface also maps the plurality of coded bits to a plurality of constellation symbols, and maps the plurality of constellation symbols to a first plurality of data subcarriers corresponding to the first portion of the OFDM symbol. It is configured as follows. The network interface is also configured to set a subset of data subcarriers in the first plurality of data subcarriers to one or more predetermined values. Furthermore, the network interface further maps the plurality of constellation symbols to a second plurality of data subcarriers corresponding to the second portion of the OFDM symbol, and a subset of data subcarriers in the second plurality of data subcarriers. Is configured to set to one or more predetermined values. The network interface is further configured to generate an OFDM symbol to include at least a plurality of data subcarriers corresponding to the first portion and a plurality of data subcarriers corresponding to the second portion.

  In other embodiments, the apparatus includes any combination of one or more of the following features.

  The network interface is further configured to include one or more of (i) multiple guard tones, (ii) multiple direct current (DC) tones, and (iii) multiple pilot tones in the OFDM symbol.

  Setting the subset of data subcarriers in the first plurality of data subcarriers to one or more predetermined values is at least one data in the subset of data subcarriers in the first plurality of data subcarriers. Setting the subcarrier to a null value.

  Setting the subset of data subcarriers in the second plurality of data subcarriers to one or more predetermined values is at least one data in the subset of data subcarriers in the second plurality of data subcarriers. Setting the subcarrier to a null value.

  Setting the subset of data subcarriers in the first plurality of data subcarriers to one or more predetermined values is at least one data in the subset of data subcarriers in the first plurality of data subcarriers. Setting the subcarrier to a non-zero value.

  Setting the subset of data subcarriers in the second plurality of data subcarriers to one or more predetermined values is at least one data in the subset of data subcarriers in the second plurality of data subcarriers. Setting the subcarrier to a non-zero value.

  The network interface maps a plurality of constellation symbols to a third plurality of data subcarriers corresponding to a third portion of the OFDM symbol, and one subset of data subcarriers in the third plurality of data subcarriers. Or it is further configured to map to a plurality of predetermined values and generate an OFDM symbol to further include a third plurality of data subcarriers.

  The network interface is further configured to generate a physical layer (PHY) data unit preamble, the preamble including an OFDM symbol.

  The network interface is further configured to generate a data portion of a physical layer (PHY) data unit, the data portion including an OFDM symbol.

  The network interface inserts one or more additional bits into multiple information bits and duplicates multiple information bits and additional bits before encoding multiple information bits to generate multiple duplicate bits And encoding the plurality of information bits comprises encoding the plurality of replicated bits.

  The first bandwidth corresponds to bandwidth B, the second bandwidth corresponds to bandwidth mB, and m is an integer.

  Although the present invention has been described with reference to specific examples, which are intended to be illustrative only and not limiting, various modifications can be made to the disclosed embodiments without departing from the scope of the invention. Changes, additions and / or deletions may be made.

Claims (18)

A method for generating orthogonal frequency division multiplexed symbols (OFDM symbols) of data units transmitted over a communication channel, comprising:
Encoding a plurality of information bits to generate a plurality of coded bits to be included in the OFDM symbol;
Mapping the plurality of coded bits to a plurality of constellation symbols;
Mapping the plurality of constellation symbols to a first plurality of data subcarriers corresponding to a first portion of the OFDM symbol;
Setting a subset of data subcarriers in the first plurality of data subcarriers to one or more predetermined values;
Mapping the plurality of constellation symbols to a second plurality of data subcarriers corresponding to a second portion of the OFDM symbol;
Setting a subset of data subcarriers in the second plurality of data subcarriers to one or more predetermined values;
Generating the OFDM symbol to include at least the first plurality of data subcarriers and the second plurality of data subcarriers;
The plurality of information bits corresponds to a first bandwidth, the OFDM symbol includes a number of data tones corresponding to a second bandwidth, and the second bandwidth is the first bandwidth. Greater than,
Method.   Generating the OFDM symbol comprises including one or more of (i) a plurality of guard tones, (ii) a plurality of direct current (DC) tones, and (iii) a plurality of pilot tones in the OFDM symbol. The method of claim 1, further comprising: Setting the subset of data subcarriers in the first plurality of data subcarriers to one or more predetermined values comprises: in the subset of data subcarriers in the first plurality of data subcarriers; Setting at least one data subcarrier to a null value;
Setting the subset of data subcarriers in the second plurality of data subcarriers to one or more predetermined values comprises: in the subset of data subcarriers in the second plurality of data subcarriers; Setting at least one data subcarrier to the null value,
The method according to claim 1 or 2. Setting the subset of data subcarriers in the first plurality of data subcarriers to one or more predetermined values comprises: in the subset of data subcarriers in the first plurality of data subcarriers; Setting at least one data subcarrier to a non-zero value;
Setting the subset of data subcarriers in the second plurality of data subcarriers to one or more predetermined values comprises: in the subset of data subcarriers in the second plurality of data subcarriers; Setting at least one data subcarrier to the non-zero value;
The method according to claim 1 or 2. Mapping the plurality of constellation symbols to a third plurality of data subcarriers corresponding to a third portion of the OFDM symbol;
Setting a subset of data subcarriers in the third plurality of data subcarriers to one or more predetermined values;
Generating the OFDM symbol further comprises including the third plurality of data subcarriers in the OFDM symbol;
The method according to any one of claims 1 to 4. Generating a physical layer (PHY) data unit preamble;
The preamble includes the OFDM symbol;
6. A method according to any one of claims 1-5. Generating a data portion of a physical layer (PHY) data unit;
The data portion includes the OFDM symbol;
6. A method according to any one of claims 1-5. (I) inserting one or more additional bits into the plurality of information bits; (ii) duplicating the plurality of information bits and the additional bits before encoding the plurality of information bits; Generating a generated bit,
Encoding the plurality of information bits comprises encoding the plurality of replicated bits;
The method according to any one of claims 1 to 7. The first bandwidth corresponds to bandwidth B, the second bandwidth corresponds to bandwidth mB,
m is an integer,
9. A method according to any one of claims 1 to 8. Encoding a plurality of information bits to generate a plurality of coded bits to be included in an OFDM symbol;
Mapping the plurality of coded bits to a plurality of constellation symbols;
Mapping the plurality of constellation symbols to a first plurality of data subcarriers corresponding to a first portion of the OFDM symbol;
Setting a subset of data subcarriers in the first plurality of data subcarriers to one or more predetermined values;
Mapping the plurality of constellation symbols to a second plurality of data subcarriers corresponding to a second portion of the OFDM symbol;
Setting a subset of data subcarriers in the second plurality of data subcarriers to one or more predetermined values;
A network interface configured to generate the OFDM symbol to include at least the plurality of data subcarriers corresponding to the first portion and the plurality of data subcarriers corresponding to the second portion;
The plurality of information bits corresponds to a first bandwidth, the OFDM symbol includes a number of data tones corresponding to a second bandwidth, and the second bandwidth is the first bandwidth. Greater than,
apparatus. The network interface is further configured to include one or more of (i) a plurality of guard tones, (ii) a plurality of direct current (DC) tones, and (iii) a plurality of pilot tones in the OFDM symbol.
The apparatus according to claim 10. The network interface sets at least one data subcarrier in the subset of data subcarriers in the first plurality of data subcarriers to a null value, and the data subcarriers in the second plurality of data subcarriers Further configured to set at least one data subcarrier in the subset to the null value;
The apparatus according to claim 10 or 11. The network interface sets at least one data subcarrier in the subset of data subcarriers in the first plurality of data subcarriers to a non-zero value, and sets data subcarriers in the second plurality of data subcarriers. 12. The apparatus of claim 10 or 11, further configured to set at least one data subcarrier in the subset to the non-zero value. The network interface is
Mapping the plurality of constellation symbols to a third plurality of data subcarriers corresponding to a third portion of the OFDM symbol;
Mapping a subset of data subcarriers in the third plurality of data subcarriers to one or more predetermined values;
14. The apparatus according to any one of claims 10 to 13, further configured to generate the OFDM symbol to further include the third plurality of data subcarriers. The network interface is
Further configured to generate a preamble of a physical layer (PHY) data unit;
The preamble includes the OFDM symbol;
15. Apparatus according to any one of claims 10 to 14. The network interface is
Further configured to generate a data portion of a physical layer (PHY) data unit;
The data portion includes the OFDM symbol;
15. Apparatus according to any one of claims 10 to 14. The network interface is
Inserting one or more additional bits into the plurality of information bits;
Further configured to replicate the plurality of information bits and the additional bit to generate a plurality of replicated bits before encoding the plurality of information bits;
Encoding the plurality of information bits comprises encoding the plurality of replicated bits;
The device according to any one of claims 10 to 16. The first bandwidth corresponds to bandwidth B, the second bandwidth corresponds to bandwidth mB,
m is an integer,
The apparatus according to any one of claims 10 to 17.

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