Communication device, communication method, and integrated circuit

Abstract

To provide a communication device capable of efficiently receiving and decoding packets.SOLUTION: The communication device is a device for detecting the format of a first received PPDU based on a first OFDM symbol which is a legacy signal field and a second OFDM symbol placed immediately after the first OFDM symbol. The second OFDM symbol in the first PPDU format includes no resource allocation information for multi-user transmission, and is derived from the legacy signal field by the first BPSK mapping rule to distinguish from the second PPDU format, in which the position of the subsequent training field is different. The second OFDM symbol in the second PPDU format is derived according to a second BPSK mapping rule that is different from the first BPSK mapping rule from the legacy signal field.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present disclosure generally relates to wireless communication systems, and more particularly to the detection of different formats of packets.

Background Art

[0002] The IEEE (Institute of Electrical and Electronics Engineers) 802.11 working group is developing an 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 legacy 802.11a / g / n / ac standards. OFDMA (Orthogonal Frequency Division Multiple Access) multi-user transmission is envisioned 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 an OFDM system, the input data stream is divided into several parallel sub-streams with a lower data rate (and thus an increased symbol duration), and each sub-stream is modulated with a respective orthogonal subcarrier and transmitted. By increasing the symbol duration, the robustness of the OFDM system against channel delay spread is improved. Furthermore, by introducing a GI (Guard Interval), inter-symbol interference can be completely removed as long as the GI duration is longer than the channel delay spread. Additionally, OFDM modulation can be realized by an efficient IFFT (Inverse Fast Fourier Transform) that enables the use of multiple subcarriers with low complexity. In an OFDM system, 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 among multiple users across the time and frequency resources of an OFDM system.

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

Non-Patent Document 2

Non-Patent Document 3

Non-Patent Document 4

Non-Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0005] 802.11ax packets may coexist with legacy 802.11a / g / n / ac packets within an 802.11 wireless network. Therefore, a transmission method and a transmission apparatus that enable a receiving unit to efficiently receive and decode packets when the receiving unit may receive packets of different formats are desired.

Means for Solving the Problems

[0006] The transmission apparatus of the present disclosure includes, during operation, a packet generation unit that generates a packet including a legacy short training field, a legacy long training field, a legacy signal field (L-SIG), a repeated 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, wherein the second non-legacy signal field is optionally present in the packet, and the packet generation unit generates the packet by configuring the RL-SIG in different ways according to the presence or absence of the second non-legacy signal field in the packet, and a transmission unit that transmits the generated packet during operation.

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

[0008] With the packet format detection transmission method and transmission device of the present disclosure, when the receiving unit may receive packets of different formats, the receiving unit can efficiently receive and decode the packets.

Brief Description of the Drawings

[0009]

Figure 1A

Figure 1B

Figure 1C

Figure 2A

Figure 2B

Figure 2C

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

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

[0011] <BASIC KNOWLEDGE FORMING THE BASIS OF THE PRESENT DISCLOSURE> FIGS. 1A, 1B, and 1C show various formats of legacy 802.11a / g / n / ac packets. FIG. 1A shows the format of a packet 100A compliant with the IEEE 802.11a / g standard. FIG. 1B shows the format of a high throughput (HT) packet 100B compliant with the IEEE 802.11n standard. FIG. 1C shows the format of a very high throughput (VHT) packet 100C compliant with the IEEE 802.11ac standard.

[0012] Referring to FIG. 1A, the 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, a legacy signal field (L-SIG) 106A, and a data field 120A. The L-STF 102A and L-LTF 104A are mainly used for packet detection, automatic gain control (AGC) setting, frequency offset estimation, time synchronization, and channel estimation. The lengths of both the L-STF 102A and L-LTF 104A are 8 microseconds.

[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, reserved bits 204, a 12-bit L_Length field 206, a parity bit 208, and six tail bits 210. The L_Rate field 202 carries information regarding 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 data amount of the data field 120A in octets. The parity bit 208 provides even parity over the first 17 bits. Since the single parity bit 208 in the L-SIG 106A may be problematic under lower signal-to-noise ratio (SNR) conditions, the reserved bits 204 may be additionally used as additional parity in some implementations. Since the L-SIG 106A is encoded separately from the data field 120A, the tail bits 210 are set to zero and used to flush the encoder and decoder. Note that it is important not only for the receiving unit targeted by the packet 100A to correctly decode the L-SIG 106A, but also for nearby stations to correctly decode the L-SIG 106A in order to appropriately reserve channel access.

[0014] FIG. 2C is a block diagram showing a transmission section 250 of the L-SIG 106A in the 802.11a / g packet 100A of FIG. 1A. The transmission section 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 encoding 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 modulator 256 converts the 48 coded and interleaved bits into 48 BPSK information symbols, where the input bit "1" is mapped to the symbol "+1", while the input bit "0" is mapped to the symbol "-1". Also, the 48 BPSK information symbols are placed in the subcarriers -26 to 26 of the OFDM symbol excluding the pilot subcarriers 21, -7, 7, and 21 and the DC subcarrier 0 set to 0. The pilot insertion block 258 inserts four pilot signals {+1, +1, +1, -1} into the pilot subcarriers -21, -7, 7, and 21 of the OFDM symbol for performing robust coherent detection against frequency offset and phase noise. The IFFT block 260 executes an IFFT operation on the 52 information and pilot symbols to generate an OFDM symbol having a length of 3.2 microseconds. The GI addition block 262 prepends a cyclic prefix of 0.8 microseconds to the OFDM symbol, and as a result, the SIG 106A becomes an OFDM symbol of 4 microseconds.

[0015] Details of the transmission processing of the L-STF 102A, 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 L-STF 102B, L-LTF 104B, and L-SIG 106B, an HT signal field (HT-SIG) 110B, an HT short training field (HT-STF) 112B, a HE preamble including 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 in the same manner as the L-SIG 106A of the 802.11a / g packet 100A shown in FIG. 1A. However, it is different in that a cyclic shift is applied to the L-SIG 106B of the HT packet 100B to enable multi-spatial stream transmission via a plurality of antennas.

[0018] The HT-SIG 110B includes 48 information bits used to interpret the remaining HT packet 100B. The 48 HT-SIG bits are BCC-encoded at a rate of 1 / 2 to become 96 bits. These are divided 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, the input bit "0" is mapped to the symbol "-j", while the input bit "1" is mapped to the symbol "+j". Then, an IFFT operation is performed on each symbol to generate an OFDM waveform with a length of 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 of the HE-SIG 110B having a length of 4 microseconds.

[0019] The HT-STF 112B is used to reset the AGC and reduce the dynamic range requirements of an 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 processing of the L-STF 102B, L-LTF 104B, HT-STF 112B, HT-LTF 114B, and HT data field 120B can be found in the IEEE 802.11n standard.

[0021] Referring to FIG. 1C, the VHT packet 100C includes a legacy preamble including the L-STF 102C, L-LTF 104C, and L-SIG 106C, 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, as well as a VHT preamble, and a VHT data field 120C.

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

[0023] VHT-SIG-A 110C contains 48 information bits that are used to interpret the remaining VHT packets 100C. The 48 VHT-SIG-A bits are BCC-encoded at rate 1 / 2, resulting in 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 QPSK-modulated. A pilot subcarrier is inserted into each symbol. Then, an IFFT operation is performed on each symbol to generate an OFDM waveform with a length of 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 of HE-SIG-A1 110C-1 and HE-SIG-A2 110C-2 being a 4-microsecond OFDM symbol.

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

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

[0026] Note that resetting the AGC is important for performance prior to receiving the HT-LTF 114B or VHT-LTF 114C. For several reasons, significant gain changes can occur at the start of the HT-STF 112B or VHT-STF 112C. For example, changes in the cyclic shift (from 200 to 600 microseconds on the transmitted spatial stream) can significantly change the effective radio channel. Transmit beamforming can also result in an increase in the received signal gain of 6 - 10 dB, and the transmit antenna diversity scheme and spatial expansion (according to the IEEE 802.11n or 802.11ac standard) starting in the 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 format of the legacy 802.11a / g / n / ac packets shown in FIGS. 1A to 1C, the 802.11n / ac receiver can easily detect the format of the incoming packet. As shown in FIG. 1A, the BPSK-modulated L-SIG arrives simultaneously in the preamble of the 802.11a / g packet 100A when it arrives in the preamble of the HT packet 100B in FIG. 1B and the preamble of the VHT packet 100C in FIG. 1C. The next symbol following 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 regard, when the 802.11n receiver detects a QBPSK-modulated symbol immediately after the BPSK-modulated L-SIG, the 802.11n receiver can know that the incoming packet is in the 802.11n format. Otherwise, the 802.11n receiver determines that the incoming packet is in the 802.11a / g format. In the same regard, when the 802.11ac receiver detects a QPSK (Quadrature Phase Shift Keying) -modulated symbol or a modulation symbol by a higher modulation method immediately after the BPSK-modulated L-SIG, the 802.11ac receiver can know that the incoming packet is in the 802.11a / g format. When the modulation of the symbol is QBPSK, the 802.11ac receiver can know that the incoming packet is in the 802.11n format. However, when the modulation method of the symbol is BPSK, the incoming packet may be in either the 802.11a / g format or the 802.11ac format. This means that the 802.11ac receiver cannot distinguish the formats. Due to the modulation of VHT-SIG-A2 110C-2 being QBPSK for the next symbol (i.e., the second symbol following L-SIG in the time domain), the 802.11ac receiver can distinguish between the 802.11a / g format and the 802.11ac format.

[0028] As described above, the 802.11n / ac receiving unit can determine that the incoming packet has an 802.11n format after receiving the first symbol following the L-SIG in the time domain. Since the period required for the 802.11n / ac receiving unit 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 receiving unit. Therefore, the 802.11n / ac receiving unit has sufficient time to appropriately reset the AGC. However, the 802.11ac receiving unit 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 the detection of the VHT packet cannot be completed before the VHT-STF 112C is received by the 802.11ac receiving unit, and as a result, the 802.11ac receiving unit cannot take sufficient time to appropriately reset the AGC.

[0029] According to the IEEE 802.11n or 802.11ac standard, the HT packet 100B or the VHT packet 100C is retained by the 802.11a / g device that receives the HT packet 100B or the VHT packet 100C for the 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 the 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 the VHT packet 100C is set as follows.

[0030]

Number

[0031] Where 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 3.

[0032] Figure 3 shows the format of the HE packet 300 compliant with the IEEE 802.11ax specification framework document. The HE packet 300 includes a legacy preamble including L-STF 302, L-LTF 304, and 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 in the same manner as the L-SIG 106A of the 802.11a / g packet 100A shown in FIGS. 2A, 2B, and 2C. However, it is different in that a cyclic shift is applied to the L-SIG 306 of the HE packet 300 to enable multi-spatial stream transmission via a plurality of antennas.

[0034] The RL-SIG 308 is used to assist in the detection of the format of the HE packet 300. According to the prior art, the RL-SIG 308 repeats the content of the L-SIG 306 and is transmitted in the same manner as the L-SIG 306. As a result, the RL-SIG 308 also becomes a 4-microsecond OFDM symbol.

[0035] HE-SIG-A 310 carries common control information necessary for interpreting the remaining HE packets 300, such as channel bandwidth. 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. HE-SIG-A 310 is transmitted in the same way as VHT-SIG-A 110C. More specifically, the HE-SIG-A bits are BCC encoded at a rate of 1 / 2. These are divided into two symbols (i.e., HE-SIG-A1 310-1A and HE-SIG-A2 310-2A), each symbol is interleaved and BPSK modulated. Pilot subcarriers are inserted into each symbol. Then, an IFFT operation is performed on each symbol to generate an OFDM waveform with a length of 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 of HE-SIG-A1 310-1A and HE-SIG-A2 310-2A being a 4-microsecond OFDM symbol. On the other hand, the second type of HE-SIG-A 310 consists of four symbols, namely, 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 content of HE-SIG-A1 310-1A and is generated in the same way as HE-SIG-A1 310-1A, except that the interleaver is bypassed. Similarly, RHE-SIG-A2 310-2B repeats the content of HE-SIG-A2 310-2A and is generated in the same way as HE-SIG-A2 310-2A, except that the interleaver is bypassed. The second type of HE-SIG-A 310 can be used to enhance the robustness of the transmission of HE-SIG-A 310 in an outdoor scenario.The HE-SIG-A 310-1A immediately following the RL-SIG 308 is also BPSK modulated, so that legacy 802.11a / g / n / ac devices detect the HE packet 300 as an 802.11a / g packet.

[0036] It is necessary to indicate the type of the HE-SIG-A 310 before the HE-SIG-A 310 so that the HE packet 300 can be properly processed by the 802.11ax receiver. 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 an early indication of the type of the HE-SIG-A 310.

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

[0040] HE-SIG-B 312 includes resource allocation information and per-user allocation information for a designated receiving device, especially for downlink (DL) multi-user (MU) transmission. HE-SIG-B 312 does not exist in the HE packet 300 when it is intended to be used for single user (SU) transmission or uplink (UL) MU transmission. For UL MU transmission, resource allocation information for a designated transmitting device and per-user allocation information are preset at the access point and transmitted by the access point to the designated transmitting device within a trigger frame.

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

[0042] The signaling within HE-SIG-A 310 can be used to indicate the presence of HE-SIG-B 312 within 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 both symbols of HE-SIG-A 310 are encoded together, the 802.11ax receiver does not know whether HE-SIG-B 312 is present until after the entire HE-SIG-A 310 is decoded. This means that the detection of an HE packet 300 without HE-SIG-B 312 (i.e., with HE-STF 314 following immediately after HE-SIG-A 310) cannot be completed before the HE-STF 314 is received by the 802.11ax receiver, and as a result, the 802.11ax receiver does not have enough time to properly reset the AGC. Therefore, it is important to indicate the presence of HE-SIG-B 312 within the HE packet 300 before HE-SIG-A 310.

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

[0044] Details of the transmission processing of L-STF 302, L-LTF 304, HE-SIG-B 312, HE-STF 314, HE-LTF 316, and the 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. 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. Regarding the iterative detection, it is preferable to perform a correlation over the data subcarriers between the L-SIG and the symbol immediately following the L-SIG after FFT (Fast Fourier Transform) processing. At step 406, if the correlation value is greater than a predetermined threshold (i.e., if it passes the iterative detection), method 400 proceeds to step 408. Otherwise, method 400 proceeds to step 412.

[0046] At step 408, the wireless communication device performs maximal ratio combining (MRC) on the L-SIG and the symbol immediately following the L-SIG, and then the combined L-SIG symbol is demodulated and decoded. At step 410, the wireless communication device checks the content of the decoded L-SIG. When the following conditions, namely, the 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 are satisfied, it passes the L-SIG content check, the wireless communication device determines that the packet is in the 802.11ax format, and method 400 ends at step 414. Otherwise, the wireless communication device performs legacy 802.11a / g / n / ac packet detection at step 412.

[0047] The transmission process and content setting of the RL-SIG 308 in the HE packet 300 help to distinguish an 802.11ax packet from a legacy 802.11a / g / n / ac packet, but cannot help to indicate the presence of the HE-SIG-B 312 in the HE packet 300.

[0048] Next, various embodiments for the transmission process of RL-SIG 308 in the HE packet 300 and / or content setting, and corresponding methods for packet format detection of the present disclosure will be described in more detail.

[0049] <First Embodiment> According to the first embodiment of the present disclosure, the transmission process of RL-SIG 308 in the HE packet 300 is changed to facilitate the indication of the presence of 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] FIG. 5 is a block diagram showing a transmission unit 500 of RL-SIG 308 in the HE packet 300 of FIG. 3 according to the first embodiment of the present disclosure. The transmission unit 500 includes a BCC encoding unit 502, an interleaver 504, a BPSK modulation unit 506, a mapping rule selection unit 520, a pilot insertion block 508, an IFFT block 510, and a GI addition block 512. The BCC encoding unit 502, the interleaver 504, the pilot insertion block 508, the IFFT block 510, and the GI addition block 512 have the same functions as the corresponding ones in the transmission unit 200C shown in FIG. 2C. The modulation method used by the BPSK modulation unit 506 can be configured according to the presence of HE-SIG-B 312 in the HE packet 300, which is different from the BPSK modulation unit 256 in the transmission unit 200C that uses a single modulation method.

[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 in FIG. 2C. That is, in the IQ plane, the input bit "0" is mapped to the symbol "-1", while the input bit "1" is mapped to the symbol "+1". On the other hand, according to the second BPSK mapping rule, in the IQ plane, the input bit "0" is mapped to the symbol "+1", while the input bit "1" is mapped to the symbol "-1". The BPSK mapping rule selection unit 520 selects which of the first BPSK mapping rule and 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 modulation unit 506.

[0052] FIG. 6 shows a method 600 for detecting a packet format in a wireless communication device according to the first embodiment of the present disclosure. The method 600 starts at step 602. At step 604, the wireless communication device performs repeated detection to determine whether the symbol immediately following the L-SIG in the incoming packet has the same content as the L-SIG. Regarding the repeated detection, it is preferable to perform correlation over the data subcarriers between the L-SIG and the symbol immediately following the L-SIG after FFT processing. At step 606, if the absolute value of the correlation value is greater than a predetermined threshold (i.e., if the repeated detection passes), 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 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. When 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, and then the combined L-SIG symbol is demodulated and decoded. In step 610, the wireless communication device checks the content of the decoded L-SIG. The following conditions, namely, The 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, when satisfied, pass the L-SIG content check, and the wireless communication device proceeds to step 611. Otherwise, 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 the 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, when the first mapping rule is used, the HE packet contains HE-SIG-B. Otherwise, the HE packet does not contain HE-SIG-B. Method 600 ends in step 614.

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

[0056] <Second Embodiment> According to the second embodiment of the present disclosure, the transmission process of the RL-SIG 308 in the HE packet 300 is changed to facilitate the indication of the presence of the HE-SIG-B 312 in the HE packet 300. However, the transmission process 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] FIG. 7 is a block diagram showing a transmission unit 700 of the RL-SIG 308 in the HE packet 300 according to the second embodiment of the present disclosure. The transmission unit 700 includes a BCC encoding unit 702, an interleaver 704, a BPSK modulation unit 706, a pilot pattern selection unit 720, a pilot insertion block 708, an IFFT block 710, and a GI addition block 712. The BCC encoding unit 702, the interleaver 704, the BPSK modulation unit 706, the IFFT block 710, and the GI addition block 712 have the same functions as the corresponding ones in the transmission unit 200C shown in FIG. 2C. Different from the pilot insertion block 258 in the transmission unit 200C of FIG. 2C that uses a single pilot pattern, the pilot pattern used by the pilot insertion block 708 can be configured 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 inversion 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 selection unit 720 selects which of the first pilot pattern and 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 including 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 is provided immediately after the L-SIG 306, the pilot signal included in the L-SIG 306 can be used to track the frequency and phase offsets for both the L-SIG 306 and the RL-SIG 308. Therefore, in order to indicate the presence of the HE-SIG-B 312 in the HE packet 300, it is possible to utilize the pilot pattern applied to the RL-SIG 308.

[0060] According to a 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 selection unit 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 including the HE-SIG-B 312, the first pilot pattern is used by the pilot insertion block 708. In the HE packet 300 not including the HE-SIG-B 312, the second pilot pattern is used by the pilot insertion block 708. The third pilot pattern and the fourth pilot pattern are reserved for future expansion. In another embodiment, the pilot pattern selection unit 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 and the type of the HE-SIG-A 310 in the HE packet 300. For example, in the HE packet 300 having the HE-SIG-B 312 and the first type of HE-SIG-A 310, the first pilot pattern is used by the pilot insertion block 708. In the HE packet 300 having no HE-SIG-B 312 and the first type of HE-SIG-A 310, the second pilot pattern is used by the pilot insertion block 708. In the HE packet 300 having the HE-SIG-B 312 and the second type of HE-SIG-A 310, the third pilot pattern is used by the pilot insertion block 708.In the HE packet 300 that does not have HE-SIG-B 312 and has the second type of HE-SIG-A 310, a fourth pilot pattern is used by the 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 2. In one embodiment, the pilot pattern selection unit 720 selects which of these eight 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 including the HE-SIG-B 312, the first pilot pattern is used by the pilot insertion block 708. In the HE packet 300 not including the 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 selection unit 720 selects which of these eight 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 and the type of the HE-SIG-A 310 in the HE packet 300. For example, in the HE packet 300 having the HE-SIG-B 312 and the first type of HE-SIG-A 310, the first pilot pattern is used by the pilot insertion block 708. In the HE packet 300 having no HE-SIG-B 312 and having the first type of HE-SIG-A 310, the second pilot pattern is used by the pilot insertion block 708.In the HE packet 300 having HE-SIG-B 312 and the second type of HE-SIG-A 310, a third pilot pattern is used by the pilot insertion block 708. In the HE packet 300 having no HE-SIG-B 312 but having the second type of HE-SIG-A 310, a fourth pilot pattern is used by the pilot insertion block 708. The remaining four pilot patterns are reserved for future expansion.

[0062] FIG. 8 shows 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. Regarding the iterative detection, after the FFT processing, it is preferable to perform a correlation over the data subcarriers between the L-SIG and the symbol immediately following the L-SIG. At step 806, if the correlation value is greater than a predetermined threshold (i.e., if it passes the iterative detection), the method 800 proceeds to step 808. Otherwise, the method 800 proceeds to step 812.

[0063] At step 808, the wireless communication device performs MRC on the L-SIG and the symbol immediately following the L-SIG, and then the synthesized L-SIG symbol is demodulated and decoded. At step 810, the wireless communication device checks the content of the decoded L-SIG. The following conditions, namely, the 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, when satisfied, it passes the L-SIG content check, and the wireless communication device proceeds to step 811. Otherwise, the wireless communication device performs legacy 802.11a / g / n / ac packet detection at step 812.

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

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

[0066] <The Third Embodiment> According to the third embodiment of the present disclosure, the content settings of L-SIG 306 and RL-SIG 308 in the HE packet 300 are changed to facilitate the indication of the presence of HE-SIG-B 312 in the HE packet 300. However, the transmission processing of each of 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 the HE data field 320 in the HE packet 300 remains 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 changed 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 shows a method 900 for detecting a packet format in a wireless communication device according to the third embodiment of the present disclosure. The method 900 starts at step 902. At step 904, the wireless communication device performs repeated detection to determine whether the symbol immediately following the L-SIG in the incoming packet has the same content as the L-SIG. Regarding the repeated detection, it is preferable to perform a correlation over the data subcarriers between the L-SIG and the symbol immediately following the L-SIG after the FFT processing. At step 906, if the correlation value is greater than a predetermined threshold (i.e., if the repeated detection passes), 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 synthesized 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, it passes the L-SIG content check, 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, HE-SIG-B 312 exists in the HE packet 300. Otherwise, HE-SIG-B 312 does not exist in the HE packet 300. The method 900 ends in step 914.

[0073] In the third embodiment of the present disclosure, the above-mentioned signaling based on L_Rate can not only distinguish 802.11ax packets from legacy 802.11a / g / n / ac packets, but also help indicate the presence of HE-SIG-B 312 in the HE packet 300. However, since 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 impaired as compared with 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 HE-SIG-B 312 in the HE packet 300, and 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 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 the packet format in a future IEEE 802.11 standard that needs to maintain backward compatibility with the IEEE 802.11a / g / n / ac / ax standards.

[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 signaling based on the BPSK mapping rule is used to indicate the presence of HE-SIG-B 312 in the HE packet 300, while the pilot pattern-based signaling is used to indicate the type of 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 signaling based on the BPSK mapping rule 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.

[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 can 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 transmission unit 1020, a reception unit 1030, and a plurality of antennas 1040. The controller 1010 includes a packet generation unit 1012 and a packet format detection unit 1014. The packet generation unit 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 various embodiments of the present disclosure. The generated 802.11a / g / n / ac packet is transmitted via the antenna 1040 after being processed for transmission by the transmission unit 1020 according to the IEEE 802.11a / g / n / ac standard. The generated 802.11ax packet is transmitted via the antenna 1040 after being processed for transmission by the transmission unit 1020 according to one of various embodiments of the present disclosure. On the other hand, the controller 1010 is configured to analyze and process the packet received via the antenna 1040 after the reception process by the reception unit 1030. In particular, the packet format detection unit 1014 in the controller 1010 is configured to detect the packet format according to one of 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 that cooperates with the hardware.

[0080] Also, 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 part or all of the functional blocks may be integrated on a single chip. Here, the term "LSI" is used, but depending on the degree of integration, the terms "IC", "system LSI", "super LSI", "ultra LSI" may also be used.

[0081] Also, the circuit integration is not limited to LSI, and may be realized by a dedicated circuit other than LSI or a general-purpose processor. After manufacturing the LSI, a field programmable gate array (FPGA) which is programmable, or a reconfigurable processor which enables reconnection and setting of circuit cells in the LSI may be used.

[0082] When an integrated circuit technology replacing LSI appears as a result of the progress of semiconductor technology or other technologies derived from that technology, the functional blocks can be integrated using such technology. Another possibility is an application such as biotechnology.

Industrial Applicability

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

Explanation of Signs

[0084] 1010 Controller 1012 Packet generation unit 1014 Packet format detection unit 1020 Transmission unit 1030 Reception unit 1040 Antenna

Claims

1. a receiver for receiving 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 that is arranged immediately after the first OFDM symbol, and one or more third OFDM symbols that are a first signal field that are arranged after the second OFDM symbol, the first signal field including resource allocation information for multi-user transmission; a control unit that detects a format of the received first PPDU based on the first OFDM symbol and the second OFDM symbol; A communication device comprising: 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. information for modulating the data subcarriers of the second OFDM symbol in the format of the first PPDU is the same as information for modulating the data subcarriers of the first OFDM symbol; The communication device according to claim 1 .

3. the BPSK symbols on the data subcarriers of the second OFDM symbol in the format of the second PPDU are inverted BPSK symbols on the data subcarriers of the first OFDM symbol; The communication device according to claim 1 .

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

5. receiving 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; detecting a format of the received first PPDU based on the first OFDM symbol and the second OFDM symbol; A communication method comprising: 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. information for modulating the data subcarriers of the second OFDM symbol in the format of the first PPDU is the same as information for modulating the data subcarriers of the first OFDM symbol; The communication method according to claim 5.

7. the BPSK symbols on the data subcarriers of the second OFDM symbol in the format of the second PPDU are inverted versions of the BPSK symbols on the data subcarriers of the first OFDM symbol; The communication method according to claim 5.

8. setting an automatic gain control (AGC) based on the first BPSK mapping rule; The communication method according to claim 5.

9. receiving 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; detecting a format of the received first PPDU based on the first OFDM symbol and the second OFDM symbol; An integrated circuit for controlling 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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