COMMUNICATION DEVICE, COMMUNICATION METHOD, AND INTEGRATED CIRCUIT

Abstract

To provide a communication device capable of efficiently receiving and decoding packets.SOLUTION: The communication device generates a first PPDU that includes one first OFDM symbol as a legacy signal field, one second OFDM symbol placed immediately after the first OFDM symbol, and one or more third OFDM symbols as the first signal field placed after the second OFDM symbol, and transmits the same. The first signal field includes a piece of resource allocation information for multi-user transmission. The second OFDM symbol is derived from a legacy signal field by a first method to distinguish the same from a format of the second PPDU that d does not include the resource allocation information for multi-user transmission in the first PPDU format. The amount of phase rotation of the data subcarrier for the first OFDM symbol in the format of the first PPDU is different from the amount of phase rotation of the OFDM symbol of the data subcarrier with respect to the first OFDM symbol in the format of the second PPDU.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates generally to wireless communication systems, and more particularly to detecting different formats of packets. [Background technology]

[0002] The IEEE (Institute of Electrical and Electronics Engineers) 802.11 Working Group is developing the 802.11ax HE (High Efficiency) WLAN (Wireless Local Area Network) air interface to achieve a very significant increase in the real-world throughput achieved by users in high-density scenarios while maintaining backward compatibility with the legacy 802.11a / g / n / ac standards. OFDMA (Orthogonal Frequency Division Multiple Access) multi-user transmission is envisaged as one of the most important features of 802.11ax.

[0003] OFDM (Orthogonal Frequency Division Multiplexing) is a multiplexing technique that subdivides the system bandwidth into multiple orthogonal frequency subcarriers. In OFDM systems, the input data stream is split into several parallel substreams with lower data rates (hence increased symbol duration), and the substreams are modulated and transmitted on their respective orthogonal subcarriers. The increased symbol duration improves the robustness of OFDM systems with respect to channel delay spread. Furthermore, by introducing GI (Guard Interval), inter-symbol interference can be completely eliminated as long as the GI duration is longer than the channel delay spread. Furthermore, OFDM modulation can be realized by an efficient IFFT (Inverse Fast Fourier Transform), which allows multiple subcarriers to be used with low complexity. In OFDM systems, time and frequency resources are defined by OFDM symbols in the time domain and subcarriers in the frequency domain. OFDMA is a multiple access scheme that performs multiple operations of data streams to and from multiple users over the time and frequency resources of an OFDM system. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] IEEE 802.11-15 / 0132r9,Specification Framework for TGax,September 2015 [Non-Patent Document 2] IEEE 802.11-15 / 0579r4,802.11ax Preamble Design and Auto-detection,September 2015 [Non-Patent Document 3] IEEE 802.11-15 / 0826r3, HE-SIGA transmission for range extension, September 2015 [Non-Patent Document 4] IEEE Std 802.11ac-2013 [Non-Patent Document 5] IEEE Std 802.11-2012 Summary of the Invention [Problem to be solved by the invention]

[0005] 802.11ax packets may coexist with legacy 802.11a / g / n / ac packets in an 802.11 wireless network. Thus, a transmission method and a transmission apparatus are desired that enable a receiver to efficiently receive and decode packets when the receiver may receive packets of different formats. [Means for solving the problem]

[0006] The transmitting apparatus of the present disclosure includes a packet generating unit that, during operation, generates a packet including a legacy short training field, a legacy long training field, a legacy signal field (L-SIG), a repeating legacy signal field (RL-SIG), a first non-legacy signal field, a second non-legacy signal field, a non-legacy short training field, a non-legacy long training field, and a data field, where the second non-legacy signal field is optionally present in the packet, and the packet generating unit generates the packet by configuring the RL-SIG in a different manner depending on the presence or absence of the second non-legacy signal field in the packet, and a transmitting unit that, during operation, transmits the generated packet.

[0007] It should be noted that the general or specific disclosure may be implemented as a system, a method, an integrated circuit, a computer program, a storage medium, or any combination thereof.

[0008] The disclosed transmitting method and transmitting device for packet format detection allows a receiving unit to efficiently receive and decode packets when the receiving unit may receive packets of different formats. [Brief description of the drawings]

[0009] [Figure 1A] FIG. 1A is a diagram showing the format of a packet conforming to the IEEE 802.11a / g standard. [Figure 1B] FIG. 1B is a diagram showing the format of a HT packet conforming to the IEEE 802.11n standard. [Figure 1C] FIG. 1C is a diagram showing the format of a VHT packet conforming to the IEEE 802.11ac standard. [Figure 2A] FIG. 2A is a diagram showing the format of an L-SIG in an 802.11a / g packet. [Figure 2B] FIG. 2B is a diagram showing details of the L_Rate field of the L-SIG in an 802.11a / g packet. [Figure 2C] FIG. 2C is a block diagram showing the transmission portion of the L-SIG in an 802.11a / g packet. [Diagram 3] FIG. 3 is a diagram showing the format of an HE packet conforming to the IEEE 802.11ax specification framework document. [Figure 4] FIG. 4 is a flow chart illustrating a method for detecting a packet format according to the prior art. [Diagram 5] FIG. 5 is a block diagram illustrating an example of a transmission unit of an RL-SIG in an HE packet according to the first embodiment of the present disclosure. [Figure 6]FIG. 6 is a flowchart illustrating an example of a method for detecting a packet format according to the first embodiment of the present disclosure. [Figure 7] FIG. 7 is a block diagram illustrating an example of a transmission unit of an RL-SIG in an HE packet according to the second embodiment of the present disclosure. [Figure 8] FIG. 8 is a flowchart illustrating an example of a method for detecting a packet format according to the second embodiment of the present disclosure. [Figure 9] FIG. 9 is a flowchart illustrating an example of a method for detecting a packet format according to the third embodiment of the present disclosure. [Figure 10] FIG. 10 is a block diagram illustrating a configuration example of a wireless communication device according to the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Various embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. In the following description, detailed descriptions of known functions and configurations are omitted for clarity and conciseness.

[0011] <Basic knowledge that forms the basis of this disclosure> 1A, 1B and 1C show various formats of legacy 802.11a / g / n / ac packets. FIG. 1A shows the format of a packet 100A conforming to the IEEE 802.11a / g standard. FIG. 1B shows the format of a high throughput (HT) packet 100B conforming to the IEEE 802.11n standard. FIG. 1C shows the format of a very high throughput (VHT) packet 100C conforming to the IEEE 802.11ac standard.

[0012] Referring to FIG. 1A, an 802.11a / g packet 100A includes a legacy preamble including a legacy short training field (L-STF) 102A, a legacy long training field (L-LTF) 104A, and a legacy signal field (L-SIG) 106A, as well as a data field 120A. The L-STF 102A and L-LTF 104A are primarily used for packet detection, automatic gain control (AGC) settings, frequency offset estimation, time synchronization, and channel estimation. Both the L-STF 102A and the L-LTF 104A are 8 microseconds long.

[0013] FIG. 2A shows the format of the L-SIG 106A in the 802.11a / g packet 100A of FIG. 1A. The L-SIG 106A includes a 4-bit L_Rate field 202, a reserved bit 204, a 12-bit L_Length field 206, a parity bit 208, and six tail bits 210. The L_Rate field 202 carries information about the modulation type and coding rate used in the data field 120A. Details of the L_Rate field 202 are shown in FIG. 2B. The L_Length field 206 indicates the amount of data in octets in the data field 120A. The parity bit 208 provides even parity over the first 17 bits. Because the single parity bit 208 in the L-SIG 106A can be problematic in lower signal-to-noise ratio (SNR) conditions, the reserved bit 204 may additionally be used as additional parity in some implementations. Since L-SIG 106A is encoded separately from data field 120A, tail bits 210 are set to zero and are used to flush the encoder and decoder. Note that not only is it important that the intended receiver of packet 100A correctly decodes L-SIG 106A, nearby stations must also correctly decode L-SIG 106A in order to properly reserve channel access.

[0014] 2C is a block diagram showing a transmitter 250 of the L-SIG 106A in the 802.11a / g packet 100A of FIG. 1A. The transmitter 250 includes a binary convolutional code (BCC) encoder 252, an interleaver 254, a binary phase shift keying (BPSK) modulator 256, a pilot insertion block 258, an IFFT block 260, and a GI addition block 262. The BCC encoder 252 performs BCC coding on the 24 information bits of the L-SIG 106A at a coding rate of 1 / 2 to generate 48 coded bits. The interleaver 254 performs an interleaving operation on the 48 coded bits according to a predetermined interleaving rule. The BPSK modulation unit 256 converts the 48 coded and interleaved bits into 48 BPSK information symbols, where an input bit "1" is mapped to the symbol "+1", while an input bit "0" is mapped to the symbol "-1". The 48 BPSK information symbols are also inserted into subcarriers -26 to 26 of the OFDM symbol, except for pilot subcarriers 21, -7, 7 and 21, and DC subcarrier 0, which is set to 0. The pilot insertion block 258 inserts four pilot signals {+1, +1, +1, -1} into pilot subcarriers -21, -7, 7 and 21 of the OFDM symbol to perform coherent detection that is robust against frequency offset and phase noise. The IFFT block 260 performs an IFFT operation on the 52 information and pilot symbols to generate an OFDM symbol with a length of 3.2 microseconds. The GI addition block 262 prepends a 0.8 microsecond cyclic prefix to the OFDM symbol, resulting in a 4 microsecond OFDM symbol for SIG 106A.

[0015] Details of the transmission process of the L-STF 102A, the L-LTF 104A and the data field 120A can be found in the IEEE 802.11a / g standard.

[0016] Referring to FIG. 1B, the HT packet 100B includes a legacy preamble including an L-STF 102B, an L-LTF 104B, and an L-SIG 106B, an HE preamble including an HT signal field (HT-SIG) 110B, an HT short training field (HT-STF) 112B, and an HT long training field (HT-LTF) 114B, and an HT data field 120B.

[0017] The L-SIG 106B of the HT packet 100B is defined and transmitted similarly to the L-SIG 106A of the 802.11a / g packet 100A shown in Figure 1A, except that a cyclic shift is applied to the L-SIG 106B of the HT packet 100B to enable multi-spatial stream transmission over multiple antennas.

[0018] The HT-SIG 110B contains 48 information bits used to interpret the remaining HT packet 100B. The 48 HT-SIG bits are BCC coded at a rate of 1 / 2, resulting in 96 bits. These are split into two symbols, namely HT-SIG1 110B-1 and HT-SIG2 110B-2. Each symbol is interleaved, BPSK mapped, and pilot subcarriers are inserted. To facilitate packet format detection, the two symbols of the HT-SIG 110B are modulated by BPSK with a 90 degree rotation (i.e., quadrature BPSK (QBPSK)). In other words, an input bit "0" is mapped to the symbol "-j", while an input bit "1" is mapped to the symbol "+j". Then, an IFFT operation is performed on each symbol to generate an OFDM waveform of length 3.2 microseconds. A cyclic shift is applied and a 0.8 microsecond cyclic prefix is ​​prepended to the OFDM waveform, resulting in each HE-SIG 110B symbol being 4 microseconds long.

[0019] The HT-STF 112B is used to reset the AGC and reduce the dynamic range requirements of the analog-to-digital converter (ADC). The HT-LTF 114B is provided for MIMO (Multiple Input Multiple Output) channel estimation to receive and equalize the HT data field 120B.

[0020] Details of the transmission process of the L-STF 102B, the L-LTF 104B, the HT-STF 112B, the HT-LTF 114B and the HT data field 120B can be found in the IEEE 802.11n standard.

[0021] Referring to FIG. 1C, a VHT packet 100C includes a legacy preamble including an L-STF 102C, an L-LTF 104C and an L-SIG 106C, a VHT preamble including a first VHT signal field (VHT-SIG-A) 110C, a VHT short training field (VHT-STF) 112C, a VHT long training field (VHT-LTF) 114C and a second VHT signal field (VHT-SIG-B) 116C, and a VHT data field 120C.

[0022] The L-SIG 106C of the VHT packet 100C is defined and transmitted in a manner similar to the L-SIG 106B of the HT packet 100B shown in FIG. 2B.

[0023] VHT-SIG-A 110C contains 48 information bits used to interpret the remaining VHT packet 100C. The 48 VHT-SIG-A bits are BCC coded at rate 1 / 2 to yield 96 bits. These are split into two symbols (i.e., VHT-SIG-A1 110C-1 and VHT-SIG-A2 110C-2) and each symbol is interleaved. VHT-SIG-A1 110C-1 is BPSK modulated and VHT-SIG-A2 110C-2 is QBPSK modulated. A pilot subcarrier is inserted into each symbol. An IFFT operation is then performed on each symbol to generate an OFDM waveform of length 3.2 microseconds. A cyclic shift is applied and a 0.8 microsecond cyclic prefix is ​​prepended to the OFDM waveform, resulting in each symbol in HE-SIG-A1 110C-1 and HE-SIG-A2 110C-2 being a 4 microsecond OFDM symbol.

[0024] The VHT-STF 112C is used to reset the AGC and reduce the dynamic range requirements of the ADC. The VHT-LTF 114C provides for MIMO channel estimation to receive and equalize the VHT data field 120C.

[0025] Details of the transmission process of the L-STF 102C, L-LTF 104C, VHT-STF 112C, VHT-LTF 114C, VHT-SIG-B 116C and VHT Data field 120C can be found in the IEEE 802.11ac standard.

[0026] Note that resetting the AGC is critical for performance before receiving HT-LTF 114B or VHT-LTF 114C. Significant gain changes can occur at the beginning of HT-STF 112B or VHT-STF 112C for several reasons. For example, a cyclic shift change (from 200 to 600 microseconds on the transmitted spatial stream) can significantly change the effective wireless channel. Transmit beamforming can also result in a 6-10 dB increase in received signal gain, and transmit antenna diversity schemes and spatial extension (per the IEEE 802.11n or 802.11ac standards) beginning in HT-STF 112B or VHT-STF 112C can further change the channel. These sudden changes need to be compensated for by the AGC to prevent effects such as ADC saturation (clipping).

[0027] According to the formats of the legacy 802.11a / g / n / ac packets shown in Figures 1A-1C, it is possible for an 802.11n / ac receiver to easily detect the format of an incoming packet. As shown in Figure 1A, the BPSK modulated L-SIG arrives in the preamble of the 802.11a / g packet 100A at the same time as it arrives in the preamble in the HT packet 100B in Figure 1B and in the preamble in the VHT packet 100C in Figure 1C. The next symbol following the L-SIG in the time domain is the data field 120A in 802.11a / g, the QBPSK modulated HT-SIG1 110B-1 in 802.11n, and the BPSK modulated VHT-SIG-A1 110C-1 in 802.11ac. In this respect, if the 802.11n receiver detects a QBPSK modulation symbol immediately after the BPSK modulation L-SIG, the 802.11n receiver knows that the incoming packet is in 802.11n format. Otherwise, the 802.11n receiver determines that the incoming packet is in 802.11a / g format. In the same respect, if the 802.11ac receiver detects a QPSK (Quadrature Phase Shift Keying) modulation symbol or a modulation symbol with a higher modulation scheme immediately after the BPSK modulation L-SIG, the 802.11ac receiver knows that the incoming packet is in 802.11a / g format. If the modulation of the symbol is QBPSK, the 802.11ac receiver knows that the incoming packet is in 802.11n format. However, if the modulation of a symbol is BPSK, the incoming packet can be either 802.11a / g or 802.11ac format. This means that the 802.11ac receiver cannot distinguish the formats. By the next symbol (i.e., the second symbol following the L-SIG in the time domain), the 802.11ac receiver can distinguish between 802.11a / g and 802.11ac formats because the modulation of VHT-SIG-A2 110C-2 is QBPSK.

[0028] As described above, the 802.11n / ac receiver can determine that the incoming packet has an 802.11n format after receiving the first symbol following the L-SIG in the time domain. Because the period required by the 802.11n / ac receiver to detect the packet format is about one symbol time (or about 4 microseconds), the detection of the HT packet can be completed before the HT-STF 112B is received by the 802.11n / ac receiver. Therefore, the 802.11n / ac receiver has enough time to properly reset the AGC. However, the 802.11ac receiver can only determine that the incoming packet has an 802.11ac format after receiving the second symbol following the L-SIG in the time domain. This means that detection of the VHT packet cannot be completed before the VHT-STF 112C is received by the 802.11ac receiver, and as a result the 802.11ac receiver does not have enough time to properly reset the AGC.

[0029] According to the IEEE 802.11n or 802.11ac standard, the HT packet 100B or VHT packet 100C is reserved by an 802.11a / g device receiving the HT packet 100B or VHT packet 100C for a duration indicated by the L_Length and L_Rate fields in the L-SIG. The L_Rate field of the L-SIG in the HT packet 100B or VHT packet 100C is set to indicate a rate of 6 megabits per second (Mbps). The L_Length field of the L-SIG in the HT packet 100B or VHT packet 100C is set as follows:

[0030]

number

[0031] In the formula, TXTIME is the transmission time of the HT packet 100B or the VHT packet 100C. In other words, the value of the L_Length field of the L-SIG in the HT packet 100B or the VHT packet 100C is always a multiple of three.

[0032] 3 illustrates the format of an HE packet 300 that conforms to the IEEE 802.11ax specification framework document. The HE packet 300 includes a legacy preamble including an L-STF 302, an L-LTF 304, and an L-SIG 306, an HE preamble including a repeated L-SIG field (RL-SIG) 308, a first HE signal field (HE-SIG-A) 310, a second HE signal field (HE-SIG-B) 312, an HE short training field (HE-STF) 314, and an HE long training field (HE-LTF) 316, and an HE data field 320.

[0033] The L-SIG 306 of the HE packet 300 is defined and transmitted similarly to the L-SIG 106A of the 802.11a / g packet 100A shown in Figures 2A, 2B and 2C, except that a cyclic shift is applied to the L-SIG 306 of the HE packet 300 to enable multi-spatial stream transmission over multiple antennas.

[0034] The RL-SIG 308 is used to aid in detecting the format of the HE packet 300. According to the prior art, the RL-SIG 308 repeats the contents of the L-SIG 306 and is transmitted similarly to the L-SIG 306, resulting in the RL-SIG 308 also being a 4 microsecond OFDM symbol.

[0035] The HE-SIG-A 310 carries common control information, such as channel bandwidth, required to interpret the rest of the HE packet 300. There are two different types of HE-SIG-A 310. The first type of HE-SIG-A 310 consists of two symbols, namely HE-SIG-A1 310-1A and HE-SIG-A2 310-2A. The HE-SIG-A 310 is transmitted similarly to the VHT-SIG-A 110C. More specifically, the HE-SIG-A bits are BCC coded at rate 1 / 2. They are split into two symbols (i.e., HE-SIG-A1 310-1A and HE-SIG-A2 310-2A), and each symbol is interleaved and BPSK modulated. A pilot subcarrier is inserted in each symbol. Then, an IFFT operation is performed on each symbol to generate an OFDM waveform of length 3.2 microseconds. A cyclic shift is applied and a 0.8 microsecond cyclic prefix is ​​prepended to the OFDM waveform, resulting in a 4 microsecond OFDM symbol for each symbol in HE-SIG-A1 310-1A and HE-SIG-A2 310-2A. Meanwhile, the second type of HE-SIG-A 310 consists of four symbols: HE-SIG-A1 310-1A, Repeated HE-SIG-A1 (RHE-SIG-A1) 310-1B, HE-SIG-A2 310-2A and Repeated HE-SIG-A2 (RHE-SIG-A2) 310-2B. RHE-SIG-A1 310-1B repeats the contents of HE-SIG-A1 310-1A and is generated similarly to HE-SIG-A1 310-1A, except that the interleaver is bypassed. Similarly, RHE-SIG-A2 310-2B repeats the contents of HE-SIG-A2 310-2A and is generated similarly to HE-SIG-A2 310-2A, except that the interleaver is bypassed. The second type of HE-SIG-A 310 can be used to increase the robustness of transmission of HE-SIG-A 310 in outdoor scenarios.The HE-SIG-A1 310-1A immediately following the RL-SIG 308 is also BPSK modulated, so that legacy 802.11a / g / n / ac devices will detect the HE packet 300 as an 802.11a / g packet.

[0036] In order for the HE packet 300 to be properly processed by the 802.11ax receiver, the type of HE-SIG-A 310 needs to be indicated before the HE-SIG-A 310. In one embodiment, the L_Rate fields of the L-SIG 306 and RL-SIG 308 in the HE packet 300 are set to indicate a rate of 6 Mbps, and the L_Length fields of the L-SIG 306 and RL-SIG 308 in the HE packet 300 are set as follows:

[0037]

number

[0038] where m=1 or 2 is used for early indication of type of HE-SIG-A 310.

[0039] An alternative method for early indication of the type of HE-SIG-A 310 is by two different scrambling sequences. More specifically, for a first type of HE-SIG-A 310, a first scrambling sequence is scrambled by the information bits of the RL-SIG 308 before the BCC coding applied to the information bits of the RL-SIG 308. Otherwise, a second scrambling sequence is scrambled by the information bits of the RL-SIG 308. However, referring to FIG. 4, iterative detection as part of packet format detection must be performed after demodulation and decoding of the L-SIG 306 and RL-SIG 308 and blind descrambling of the RL-SIG 308. As a result, the time required for packet format detection is significantly increased.

[0040] The HE-SIG-B 312 includes resource allocation information and per-user allocation information for designated receiving devices, particularly for downlink (DL) multiuser (MU) transmissions. The HE-SIG-B 312 is not present in the HE packet 300 if it is intended to be used for single user (SU) transmissions or uplink (UL) MU transmissions. For UL MU transmissions, the resource allocation information and per-user allocation information for designated transmitting devices are preconfigured at the access point and transmitted by the access point in a trigger frame to the designated transmitting devices.

[0041] The HE-STF 314 is used to reset the AGC and reduce the dynamic range requirements of the ADC. If the HE packet 300 is to be used for SU or DL ​​MU transmission, the HE-STF 314 has a length of 4 microseconds. Otherwise, it has a length of 8 microseconds. The HE-LTF 316 is provided for MIMO channel estimation to receive and equalize the HE data field 320.

[0042] Signaling in the HE-SIG-A 310 can be used to indicate the presence of HE-SIG-B 312 in the HE packet 300 (i.e., to indicate whether the HE packet 300 is intended to be used for DL ​​MU transmission). In this case, since the two symbols of the HE-SIG-A 310 are encoded together, the 802.11ax receiver can only know whether HE-SIG-B 312 is present or not after decoding the entire HE-SIG-A 310. This means that detection of an HE packet 300 without HE-SIG-B 312 (i.e., HE-SIG-A 310 immediately followed by HE-STF 314) cannot be completed before the HE-STF 314 is received by the 802.11ax receiver, and as a result, the 802.11ax receiver may not have enough time to properly reset the AGC. Therefore, it is important to indicate the presence of HE-SIG-B 312 in the HE packet 300 before HE-SIG-A 310.

[0043] As mentioned above, if the HE packet 300 includes HE-SIG-B 312, it is intended to be used for DL ​​MU transmissions. Otherwise, the HE packet 300 is intended to be used for either SU or UL MU transmissions, and the signaling in the HE-SIG-A 310 is intended to further indicate whether the HE packet 300 is used for a SU or UL MU transmission.

[0044] Details of the transmission processing of the L-STF 302, L-LTF 304, HE-SIG-B 312, HE-STF 314, HE-LTF 316 and HE data field 320 can be found in the IEEE 802.11ax specification framework document.

[0045] FIG. 4 shows a method 400 for detecting a packet format used in a wireless communication device according to the prior art. The method 400 starts at step 402. At step 404, the wireless communication device performs iterative detection to determine whether the symbol immediately following the L-SIG in the incoming packet has the same content as the L-SIG. For iterative detection, it is preferable to perform a correlation between the L-SIG and the symbol immediately following the L-SIG across the data subcarriers after FFT (Fast Fourier Transform) processing. At step 406, if the correlation value is greater than a predetermined threshold (i.e., if the iterative detection is passed), the method 400 proceeds to step 408. Otherwise, the method 400 proceeds to step 412.

[0046] In step 408, the wireless communication device performs maximal ratio combining (MRC) on the L-SIG and the symbol immediately following the L-SIG, after which the combined L-SIG symbol is demodulated and decoded. In step 410, the wireless communication device checks the contents of the decoded L-SIG. The following conditions are met: Parity check is OK, The value of the L_Rate field indicates a rate of 6 Mbps, and The value of the L_Length field is a multiple of 3, If is satisfied, If the L-SIG content check passes, the wireless communication device determines that the packet is in 802.11ax format, and method 400 ends at step 414. If not, the wireless communication device performs legacy 802.11a / g / n / ac packet detection at step 412.

[0047] The transmit processing and content settings of the RL-SIG 308 in the HE packet 300 serve to distinguish 802.11ax packets from legacy 802.11a / g / n / ac packets, but cannot serve to indicate the presence of HE-SIG-B 312 in the HE packet 300.

[0048] Various embodiments for transmission processing and / or content configuration of the RL-SIG 308 in the HE packet 300 and corresponding methods for packet format detection of the present disclosure will now be described in further detail.

[0049] <First embodiment> According to a first embodiment of the present disclosure, the transmission processing of the RL-SIG 308 in the HE packet 300 is modified to facilitate indicating the presence of the HE-SIG-B 312 in the HE packet 300. However, the L-STF 302, L-LTF 304, L-SIG 306, HE-SIG-A 310, HE-SIG-B 312, HE-STF 314, HE-LTF 316 and HE Data field 320 in the HE packet 300 remain unchanged.

[0050] 5 is a block diagram showing a transmitter 500 of the RL-SIG 308 in the HE packet 300 of FIG. 3 according to the first embodiment of the present disclosure. The transmitter 500 includes a BCC encoder 502, an interleaver 504, a BPSK modulator 506, a mapping rule selector 520, a pilot insertion block 508, an IFFT block 510, and a GI addition block 512. The BCC encoder 502, the interleaver 504, the pilot insertion block 508, the IFFT block 510, and the GI addition block 512 have the same functions as their counterparts in the transmitter 200C shown in FIG. 2C. The modulation scheme used by the BPSK modulator 506 is configurable according to the presence of the HE-SIG-B 312 in the HE packet 300, unlike the BPSK modulator 256 in the transmitter 200C which uses a single modulation scheme.

[0051] According to the first embodiment of the present disclosure, the BPSK modulation unit 506 supports two different modulation schemes (i.e., BPSK mapping rules). For example, the first BPSK mapping rule is the same as that used by the BPSK modulation unit 256 of FIG. 2C. That is, in the IQ plane, an input bit "0" is mapped to a symbol "-1", while an input bit "1" is mapped to a symbol "+1". On the other hand, according to the second BPSK mapping rule, in the IQ plane, an input bit "0" is mapped to a symbol "+1", while an input bit "1" is mapped to a symbol "-1". The BPSK mapping rule selection unit 520 selects whether the first BPSK mapping rule or the second BPSK mapping rule is used by the BPSK modulation unit 506 according to the presence of the HE-SIG-B 312 in the HE packet 300. For example, in the HE packet 300 including the HE-SIG-B 312, the first BPSK mapping rule is used by the BPSK modulation unit 506. Otherwise, the second BPSK mapping rule is used by the BPSK modulator 506 .

[0052] FIG. 6 shows a method 600 for detecting a packet format in a wireless communication device according to a first embodiment of the present disclosure. The method 600 starts in step 602. In step 604, the wireless communication device performs iterative detection to determine whether the symbol immediately following the L-SIG in the incoming packet has the same content as the L-SIG. For iterative detection, it is preferable to perform correlation between the L-SIG and the symbol immediately following the L-SIG across data subcarriers after FFT processing. In step 606, if the absolute value of the correlation value is greater than a predetermined threshold (i.e., if the iterative detection is passed), the method 600 proceeds to step 607. Otherwise, the method 600 proceeds to step 612.

[0053] In step 607, the wireless communication device determines the BPSK mapping rule to be applied to the symbol immediately following the L-SIG, which can be done by checking the polarity of the correlation value used in step 606. For example, if the correlation value is positive, the first mapping rule is used; otherwise, the second mapping rule is used. If the second mapping rule is used, the BPSK symbols on the data subcarriers of the symbol immediately following the L-SIG should be inverted. In step 608, the wireless communication device performs MRC on the L-SIG and the symbol immediately following the L-SIG, after which the combined L-SIG symbol is demodulated and decoded. In step 610, the wireless communication device checks the contents of the decoded L-SIG. The following conditions are met: Parity check is OK, The value of the L_Rate field indicates a rate of 6 Mbps, and The value of the L_Length field is not a multiple of 3, If is satisfied, If the L-SIG content check passes, the wireless communication device proceeds to step 611. If not, the wireless communication device performs legacy 802.11a / g / n / ac packet detection in step 612.

[0054] In step 611, the wireless communication device determines that the packet is in 802.11ax format and determines the presence of HE-SIG-B in the packet according to the BPSK mapping rule determined in step 607. For example, if the first mapping rule is used, then HE-SIG-B is present in the HE packet. Otherwise, HE-SIG-B is not present in the HE packet. The method 600 ends in step 614.

[0055] In the first embodiment of the present disclosure, the signaling based on the above-mentioned BPSK mapping rules can help not only distinguish 802.11ax packets from legacy 802.11a / g / n / ac packets, but also indicate the presence of HE-SIG-B 312 in the HE packet 300.

[0056] <Second embodiment> According to a second embodiment of the present disclosure, the transmit processing of the RL-SIG 308 in the HE packet 300 is modified to facilitate indicating the presence of the HE-SIG-B 312 in the HE packet 300. However, the transmit processing of each of the L-STF 302, L-LTF 304, L-SIG 306, HE-SIG-A 310, HE-SIG-B 312, HE-STF 314, HE-LTF 316 and HE Data field 320 in the HE packet 300 remains unchanged.

[0057] 7 is a block diagram showing a transmitter 700 of the RL-SIG 308 in the HE packet 300 according to the second embodiment of the present disclosure. The transmitter 700 comprises a BCC encoder 702, an interleaver 704, a BPSK modulator 706, a pilot pattern selector 720, a pilot insertion block 708, an IFFT block 710, and a GI addition block 712. The BCC encoder 702, the interleaver 704, the BPSK modulator 706, the IFFT block 710, and the GI addition block 712 have the same functions as their counterparts in the transmitter 200C shown in FIG. 2C. Unlike the pilot insertion block 258 in the transmitter 200C of FIG. 2C, which uses a single pilot pattern, the pilot pattern used by the pilot insertion block 708 is configurable according to the presence of the HE-SIG-B 312 in the HE packet 300.

[0058] According to the second embodiment of the present disclosure, the pilot insertion block 708 supports two different pilot patterns. For example, the first pilot pattern is the same as that used by the pilot insertion block 258, while the second pilot pattern is the inverse of the first pilot pattern. That is, the first pilot pattern is {+1, +1, +1, -1}, while the second pilot pattern is {-1, -1, -1, +1}. These two pilot patterns correspond to odd parity codes, and the Hamming distance between these two pilot patterns is 4. The pilot pattern selector 720 selects whether the first pilot pattern or the second pilot pattern is used by the pilot insertion block 708 according to the presence of the HE-SIG-B 312 in the HE packet 300. For example, in the HE packet 300 containing the HE-SIG-B 312, the first pilot pattern is used by the pilot insertion block 708. Otherwise, the second pilot pattern is used by the pilot insertion block 708.

[0059] Since the RL-SIG 308 immediately follows the L-SIG 306, the pilot signals contained in the L-SIG 306 can be used to track the frequency and phase offsets of both the L-SIG 306 and the RL-SIG 308. Thus, the pilot pattern applied to the RL-SIG 308 can be used to indicate the presence of the HE-SIG-B 312 in the HE packet 300.

[0060] According to the second embodiment of the present disclosure, the pilot insertion block 708 can support four different pilot patterns. For example, the first pilot pattern is {+1, +1, +1, +1}, the second pilot pattern is {+1, -1, +1, -1}, the third pilot pattern is {+1, +1, -1, -1}, and the fourth pilot pattern is {+1, -1, -1, +1}. These four pilot patterns are equivalent to an even parity code, and the Hamming distance between these four pilot patterns is 2. In one embodiment, the pilot pattern selector 720 selects which of these four pilot patterns is used by the pilot insertion block 708 according to the presence of the HE-SIG-B 312 in the HE packet 300. For example, in the HE packet 300 containing the HE-SIG-B 312, the first pilot pattern is used by the pilot insertion block 708. In an HE packet 300 that does not include an HE-SIG-B 312, the second pilot pattern is used by the pilot insertion block 708. The third and fourth pilot patterns are reserved for future extensions. In another embodiment, the pilot pattern selector 720 selects which of these four pilot patterns is used by the pilot insertion block 708 according to the presence of an HE-SIG-B 312 in the HE packet 300 and the type of an HE-SIG-A 310 in the HE packet 300. For example, in an HE packet 300 that has an HE-SIG-B 312 and a first type of HE-SIG-A 310, the first pilot pattern is used by the pilot insertion block 708. In an HE packet 300 that does not have an HE-SIG-B 312 and has a first type of HE-SIG-A 310, the second pilot pattern is used by the pilot insertion block 708. In an HE packet 300 having an HE-SIG-B 312 and a second type of HE-SIG-A 310 , a third pilot pattern is used by the pilot insertion block 708 .In an HE packet 300 that does not have an HE-SIG-B 312 and has a second type of HE-SIG-A 310 , a fourth pilot pattern is used by pilot insertion block 708 .

[0061] According to the second embodiment of the present disclosure, the pilot insertion block 708 can support eight different pilot patterns. For example, the first pilot pattern is {+1, +1, +1, +1}, the second pilot pattern is {+1, -1, +1, -1}, the third pilot pattern is {+1, +1, -1, -1}, the fourth pilot pattern is {+1, -1, -1, +1}, the fifth pilot pattern is {-1, -1, -1, -1}, the sixth pilot pattern is {-1, +1, -1, +1}, the seventh pilot pattern is {-1, -1, +1, +1}, and the eighth pilot pattern is {-1, +1, +1, -1}. These eight pilot patterns are equivalent to an even parity code, and the Hamming distance between these eight pilot patterns is two. In one embodiment, the pilot pattern selector 720 selects which of these eight pilot patterns are used by the pilot insertion block 708 according to the presence of HE-SIG-B 312 in the HE packet 300. For example, in an HE packet 300 that includes HE-SIG-B 312, the first pilot pattern is used by the pilot insertion block 708. In an HE packet 300 that does not include HE-SIG-B 312, the second pilot pattern is used by the pilot insertion block 708. The remaining six pilot patterns are reserved for future expansion. In another embodiment, the pilot pattern selector 720 selects which of these eight pilot patterns are used by the pilot insertion block 708 according to the presence of HE-SIG-B 312 in the HE packet 300 and the type of HE-SIG-A 310 in the HE packet 300. For example, in an HE packet 300 having an HE-SIG-B 312 and an HE-SIG-A 310 of a first type, a first pilot pattern is used by the pilot insertion block 708. In an HE packet 300 having an HE-SIG-A 310 of a first type without an HE-SIG-B 312, a second pilot pattern is used by the pilot insertion block 708.In an HE packet 300 having an HE-SIG-B 312 and an HE-SIG-A 310 of the second type, the third pilot pattern is used by the pilot insertion block 708. In an HE packet 300 having an HE-SIG-A 310 of the second type but no HE-SIG-B 312, the fourth pilot pattern is used by the pilot insertion block 708. The remaining four pilot patterns are reserved for future expansion.

[0062] FIG. 8 illustrates a method 800 for detecting a packet format in a wireless communication device according to a second embodiment of the present disclosure. The method 800 starts at step 802. At step 804, the wireless communication device performs iterative detection to determine whether the symbol immediately following the L-SIG in the incoming packet has the same content as the L-SIG. For iterative detection, it is preferable to perform correlation across data subcarriers between the L-SIG and the symbol immediately following the L-SIG after FFT processing. At step 806, if the correlation value is greater than a predetermined threshold (i.e., if the iterative detection is passed), the method 800 proceeds to step 808. Otherwise, the method 800 proceeds to step 812.

[0063] In step 808, the wireless communication device performs MRC on the L-SIG and the symbol immediately following the L-SIG, and then the combined L-SIG symbol is demodulated and decoded. In step 810, the wireless communication device checks the contents of the decoded L-SIG. The following conditions are met: Parity check is OK, The value of the L_Rate field indicates a rate of 6 Mbps, and The value of the L_Length field is not a multiple of 3, If is satisfied, If the L-SIG content check passes, the wireless communication device proceeds to step 811. If not, the wireless communication device performs legacy 802.11a / g / n / ac packet detection in step 812.

[0064] In step 811, the wireless communication device determines a pilot pattern to be applied to the symbol immediately following the L-SIG, which can be done by correlating between the pilot signal of the symbol immediately following the L-SIG and a predefined pilot pattern. The pilot pattern that achieves the maximum correlation value is determined. In step 813, the wireless communication device determines the packet is in 802.11ax format according to the pilot pattern determined in step 811 and determines the presence of HE-SIG-B in the HE packet. For example, if the first pilot pattern is used, then HE-SIG-B is present in the HE packet. Otherwise, HE-SIG-B is not present in the HE packet. The method 800 ends in step 814.

[0065] In the second embodiment of the present disclosure, the signaling based on the above mentioned pilot patterns can help not only distinguish 802.11ax packets from legacy 802.11a / g / n / ac packets, but also indicate the presence of HE-SIG-B 312 in the HE packet 300.

[0066] <Third embodiment> According to a third embodiment of the present disclosure, the content settings of the L-SIG 306 and the RL-SIG 308 in the HE packet 300 are modified to facilitate indicating the presence of the HE-SIG-B 312 in the HE packet 300. However, the transmission operations of each of the L-STF 302, L-LTF 304, L-SIG 306, RL-SIG 308, HE-SIG-A 310, HE-SIG-B 312, HE-STF 314, HE-LTF 316 and HE Data field 320 in the HE packet 300 remain unchanged.

[0067] According to the third embodiment of the present disclosure, the L_Rate fields of the L-SIG 306 and RL-SIG 308 in the HE packet 300 are modified to indicate different rates according to the presence of the HE-SIG-B 312 in the HE packet 300. For example, in the HE packet 300 including the HE-SIG-B 312, the L_Rate fields of the L-SIG 306 and RL-SIG 308 are set to indicate a rate of 9 Mbps. Otherwise, the L_Rate fields of the L-SIG 306 and RL-SIG 308 are set to indicate a rate of 12 Mbps. The L_Length fields of the L-SIG 306 and RL-SIG 308 are set as follows:

[0068]

number

[0069] where TXTIME is the transmission time of the HE packet 300.

[0070] FIG. 9 illustrates a method 900 for detecting a packet format in a wireless communication device according to a third embodiment of the present disclosure. The method 900 starts at step 902. At step 904, the wireless communication device performs iterative detection to determine whether the symbol immediately following the L-SIG in the incoming packet has the same content as the L-SIG. For iterative detection, it is preferable to perform a correlation between the L-SIG and the symbol immediately following the L-SIG across the data subcarriers after FFT processing. At step 906, if the correlation value is greater than a predetermined threshold (i.e., if the iterative detection is passed), the method 900 proceeds to step 908. Otherwise, the method 900 proceeds to step 912.

[0071] In step 908, the wireless communication device performs MRC on the L-SIG and the symbol immediately following the L-SIG, and then the combined L-SIG symbol is demodulated and decoded. In step 910, the wireless communication device checks the content of the decoded L-SIG. If the parity check is OK, the L-SIG content check is passed and the wireless communication device proceeds to step 913. Otherwise, in step 912, the wireless communication device performs legacy 802.11a / g / n / ac packet detection.

[0072] In step 913, the wireless communication device determines that the packet is in 802.11ax format according to the value of L_Rate used in step 910, and determines the presence of HE-SIG-B 312 in the HE packet 300. For example, if the value of L_Rate indicates a rate of 9 Mbps, then HE-SIG-B 312 is present in the HE packet 300. Otherwise, HE-SIG-B 312 is not present in the HE packet 300. The method 900 ends in step 914.

[0073] In the third embodiment of the present disclosure, the above-mentioned L_Rate-based signaling can help to not only distinguish 802.11ax packets from legacy 802.11a / g / n / ac packets, but also indicate the presence of HE-SIG-B 312 in the HE packet 300. However, because the L_Rate field can be set to indicate a rate greater than 6 Mbps, the maximum transmission time of the HE packet 300 indicated by the L_Length field is compromised compared to the first and second embodiments of the present disclosure.

[0074] According to the present disclosure, each of the mapping rule-based signaling according to the first embodiment, the pilot pattern-based signaling according to the second embodiment, and the L_Rate-based signaling according to the third embodiment is not limited to being used to indicate the presence of the HE-SIG-B 312 in the HE packet 300, but can be used for other packet format indications. As an example, each of the mapping rule-based signaling according to the first embodiment, the pilot pattern-based signaling according to the second embodiment, and the L_Rate-based signaling according to the third embodiment can be used to indicate the type of the HE-SIG-A 310. As another example, each of the mapping rule-based signaling according to the first embodiment, the pilot pattern-based signaling according to the second embodiment, and the L_Rate-based signaling according to the third embodiment can be used to indicate a packet format in a future IEEE 802.11 standard that needs to maintain backward compatibility with the IEEE 802.11a / g / n / ac / ax standard.

[0075] According to the present disclosure, the BPSK mapping rule based signaling according to the first embodiment and the pilot pattern based signaling according to the second embodiment can be used in combination. For example, the BPSK mapping rule based signaling is used to indicate the presence of the HE-SIG-B 312 in the HE packet 300, while the pilot pattern based signaling is used to indicate the type of the HE-SIG-A 310 in the HE packet 300.

[0076] According to the present disclosure, the BPSK mapping rule based signaling according to the first embodiment and the L_Rate based signaling according to the third embodiment can be used in combination. For example, the BPSK mapping rule based signaling is used to indicate the presence of the HE-SIG-B 312 in the HE packet 300, while the L_Rate based signaling is used to indicate the type of the HE-SIG-A 310 in the HE packet 300.

[0077] According to the present disclosure, the pilot pattern based signaling according to the second embodiment and the L_Rate based signaling according to the third embodiment can be used in combination. For example, the pilot pattern based signaling is used to indicate the presence of HE-SIG-B 312 in the HE packet 300, while the L_Rate based signaling is used to indicate the type of HE-SIG-A 310 in the HE packet 300.

[0078] <Configuration of wireless communication device> FIG. 10 is a block diagram showing a configuration example of a wireless communication device 1000 according to the present disclosure. The wireless communication device 1000 may be an access point in a centralized wireless network, a station in a centralized wireless network, or a node in a peer-to-peer wireless network. The wireless communication device 1000 includes a controller 1010, a transmitter 1020, a receiver 1030, and a plurality of antennas 1040. The controller 1010 includes a packet generator 1012 and a packet format detector 1014. The packet generator 1012 is configured to generate an 802.11a / g / n / ac packet according to the IEEE 802.11a / g / n / ac standard or an 802.11ax packet according to one of the various embodiments of the present disclosure. The generated 802.11a / g / n / ac packet is transmitted via an antenna 1040 after transmission processing by a transmitter 1020 according to the IEEE 802.11a / g / n / ac standard. The generated 802.11ax packet is transmitted via the antenna 1040 after transmission processing by the transmitter 1020 according to one of the various embodiments of the present disclosure. Meanwhile, the controller 1010 is configured to analyze and process the packet received via the antenna 1040 after reception processing by the receiver 1030. In particular, the packet format detector 1014 in the controller 1010 is configured to detect the packet format according to one of the various embodiments of the present disclosure.

[0079] In the above embodiment, the present invention is configured by hardware as an example, but the present invention may also be provided by software cooperating with hardware.

[0080] Moreover, the functional blocks used in the description of this embodiment are generally realized as LSI devices, which are integrated circuits. The functional blocks may be formed as individual chips, or some or all of the functional blocks may be integrated into a single chip. Although the term "LSI" is used here, the terms "IC," "system LSI," "super LSI," and "ultra LSI" can also be used depending on the degree of integration.

[0081] In addition, the circuit integration is not limited to LSI, but may be realized by a dedicated circuit other than LSI or a general-purpose processor. After the LSI is manufactured, a field programmable gate array (FPGA) that is programmable, or a reconfigurable processor that enables reconfiguration of the connections and settings of circuit cells in the LSI may be used.

[0082] If an integrated circuit technology that can replace LSI appears as a result of progress in semiconductor technology or other technologies derived from it, such a technology can be used to integrate functional blocks. Another possibility is applications such as biotechnology. [Industrial Applicability]

[0083] The present disclosure may be applied to a method for performing packet format detection in a wireless communication system. [Explanation of symbols]

[0084] 1010 Controller 1012 Packet Generator 1014 Packet format detector 1020 Transmitter 1030 Receiving unit 1040 Antenna

Claims

1. a control circuit for generating a first Physical Protocol Data Unit (PPDU) including a first Orthogonal Frequency Division Multiplexing (OFDM) symbol that is a legacy signal field, a second OFDM symbol disposed immediately after the first OFDM symbol, and one or more third OFDM symbols that are a first signal field disposed after the second OFDM symbol, the first signal field including resource allocation information for multi-user transmission; A communication device comprising: a transmitter that transmits the generated first PPDU, the second OFDM symbol in the format of the first PPDU does not include resource allocation information for the multi-user transmission, and is derived from the legacy signal field according to a first binary phase shift keying (BPSK) mapping rule to distinguish it from a format of a second PPDU having a different position of a subsequent training field; the second OFDM symbol in the format of the second PPDU is derived from the legacy signal field by a second BPSK mapping rule different from the first BPSK mapping rule; Communications equipment.

2. The information for modulating the data subcarriers of the second OFDM symbol in the format of the first PPDU is identical to the information for modulating the data subcarriers of the first OFDM symbol. The communication device according to claim 1 .

3. In the format of the second PPDU, the data subcarriers of the second OFDM symbol are inverted from the data subcarriers of the first OFDM symbol. The communication device according to claim 1 .

4. A receiving device that receives the first PPDU sets an automatic gain control (AGC) based on the first BPSK mapping rule. The communication device according to claim 1 .

5. generating a first Physical Protocol Data Unit (PPDU) including a first Orthogonal Frequency Division Multiplexing (OFDM) symbol that is a legacy signal field, a second OFDM symbol disposed immediately after the first OFDM symbol, and one or more third OFDM symbols that are a first signal field disposed after the second OFDM symbol, the first signal field including resource allocation information for multi-user transmission; and transmitting the generated first PPDU, the second OFDM symbol in the format of the first PPDU does not include resource allocation information for the multi-user transmission, and is derived from the legacy signal field according to a first binary phase shift keying (BPSK) mapping rule to distinguish it from a format of a second PPDU having a different position of a subsequent training field; the second OFDM symbol in the format of the second PPDU is derived from the legacy signal field by a second BPSK mapping rule different from the first BPSK mapping rule; Communication methods.

6. The information for modulating the data subcarriers of the second OFDM symbol in the format of the first PPDU is identical to the information for modulating the data subcarriers of the first OFDM symbol. The communication method according to claim 5.

7. The method of claim 6, wherein the data subcarriers of the second OFDM symbol in the format of the second PPDU are inverted from the data subcarriers of the first OFDM symbol. The communication method according to claim 5.

8. A receiving device that receives the first PPDU sets an automatic gain control (AGC) based on the first BPSK mapping rule. The communication method according to claim 5.

9. generating a first Physical Protocol Data Unit (PPDU) including a first Orthogonal Frequency Division Multiplexing (OFDM) symbol that is a legacy signal field, a second OFDM symbol disposed immediately after the first OFDM symbol, and one or more third OFDM symbols that are a first signal field disposed after the second OFDM symbol, the first signal field including resource allocation information for multi-user transmission; and transmitting the generated first PPDU. the second OFDM symbol in the format of the first PPDU does not include resource allocation information for the multi-user transmission, and is derived from the legacy signal field according to a first binary phase shift keying (BPSK) mapping rule to distinguish it from a format of a second PPDU having a different position of a subsequent training field; the second OFDM symbol in the format of the second PPDU is derived from the legacy signal field by a second BPSK mapping rule different from the first BPSK mapping rule; Integrated circuits.

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