TW201815107A - Data packet transmitting method and wireless station - Google Patents

Abstract

A data packet transmitting method and wireless station are described. The method comprises: encoding a data packet to be transmitted from a source station to a destination station; modulating encoded bits to a first set of modulated symbols using a first modulation scheme at a first data subcarrier of a resource unit, and modulating the same encoded bits to a second set of modulated symbols using a second modulation scheme at a second data subcarrier of a resource unit if dual carrier modulation (DCM) is applied; remapping the first set of modulated symbols onto a first half of data frequency subcarriers of the RU of a wireless local area network by a tone mapper, and mapping the second set of modulated symbols onto a second half of data frequency subcarriers of the RU by the same tone mapper; and transmitting the mapped information of the tone mapper to the destination station.

Description

Method for transmitting data packet and wireless station

The present invention relates to the field of wireless communication technology, and in particular, to a method and a wireless station for transmitting data packets.

IEEE 802.11 is a set of Media Access Control (MAC) and Wireless Access Area (WLAN) communications used in the Wi-Fi (2.4 GHz, 3.6 GHz, 5 GHz, and 60 GHz) frequency bands. Physical layer (PHY) specifications. The 802.11 series consists of a series of half-duplex aerial modulation technologies using the same basic protocol. Standards and amendments provide the basis for wireless networking products using the Wi-Fi band. For example, IEEE 802.11ac is a wireless network standard in the IEEE 802.11 family that is used to provide high-throughput WLANs in the 5 GHz band. A wider channel bandwidth (20MHz, 40MHz, 80MHz, and 160MHz) is proposed in the IEEE 802.11ac standard. The High Efficiency (HE) WLAN Study Group (HEW SG) is a research group in the IEEE 802.11 working group. It considers improving the spectral efficiency to increase the system throughput in high-density scenarios of wireless devices. Thanks to HEW SG, TGax (an IEEE task force) was formed and appointed to study the IEEE 802.11ax standard (which will be the successor to IEEE 802.11ac). Recently, WLANs have grown exponentially in organizations in many industries.

Orthogonal Frequency Division Multiple Access (OFDMA) is introduced in HE WLAN to allow multiple users to transmit data at the same time to enhance user experience by allocating a subset of subcarriers to different users. In OFDMA, each user is assigned a set of subcarriers called a Resource Unit (RU) (the set of subcarriers includes a pilot subcarrier and a data subcarrier). In HE WLAN, a wireless station (Wireless Station, STA) can send a minimum size RU (about 2MHz bandwidth) in uplink and downlink OFDMA. Compared with its 20MHz preamble, the power density of the STA data part is 9dB higher than its preamble. As the Clear Channel Assessment (CCA) operates on a bandwidth of 20 MHz or more, narrow-band uplink OFDMA signals are difficult to detect by CCA. Therefore, the subcarrier interference of a STA in a specific narrowband is 9dB higher than that of other subcarriers. It can be seen that narrowband interference is inherent in HE WLAN. What is needed is a solution to deal with such narrow-band interference.

In Multi-User (MU) transmission, the performance of HE-SIGB is encoded using 1x OFDM symbol duration (ie, 3.2 microseconds + loop first code time). Finally, when using the same Modulation And Coding Scheme (MCS), its performance is worse than data symbols with a 4x OFDM symbol duration (ie, 3.2 × 4 microseconds + loop first code time). HE-SIGB requires a more powerful modulation scheme. In addition, in order to expand the range of outdoor conditions, a new signal noise ratio (SNR) that is lower than MCS0 (MCS0 requires the lowest signal-to-noise ratio among all current MCS modulation schemes) is also hoped. New modulation method.

Dual Sub-Carrier Modulation (DCM) modulates the same information on a pair of sub-carriers. DCM can introduce frequency diversity into OFDM systems by sending the same information on two subcarriers that are separated in frequency. DCM can achieve low complexity and provide better performance than existing modulation schemes used in WLAN. DCM enhances reliable transmission, especially under narrow-band interference. In information theory, a Low-Density Parity-Check (LDPC) code is a linear error-correcting code, a method of transmitting through a noise transmission channel. LDPC codes are commonly used in WLAN and OFDM systems. In HE WLAN, when the bandwidth is greater than 20MHz, LDPC becomes a mandatory error control coding scheme.

In a next-generation WLAN system based on the upcoming IEEE 802.11ax standard, each STA can use one or more RUs to send signals. When the DCM is applied to a given RU, a transmission process with a new LDPC subcarrier mapping scheme (tone mapping scheme) is expected to facilitate enhanced transmission reliability under the DCM.

The invention provides a method and a wireless station for transmitting data packets, which can enhance the transmission reliability based on the DCM mechanism.

Some embodiments of the present invention relate to a method of transmitting a data packet. It may include: encoding a data packet to be sent from a source station to a destination station; if dual subcarrier modulation is applied, using a first modulation scheme on a first data subcarrier of the resource unit to modulate the encoded bits to a first Group of modulation symbols, and using a second modulation scheme on the second data subcarrier of the resource unit to modulate the encoded bits to a second group of modulation symbols; the first group of modulation symbols by a subcarrier mapper Remap to the first half-frequency data subcarrier of the resource unit, and remap the second set of modulation symbols to the second half-frequency data subcarrier of the resource unit through the same subcarrier mapper; And sending the resource unit mapped by the subcarrier mapper to the destination station.

Some embodiments of the present invention relate to a wireless station, which may include: an encoder for encoding a data packet to be sent from a source station to a destination station; a modulator, if dual subcarrier modulation is applied, A data subcarrier uses a first modulation scheme to modulate the encoded bits to a first set of modulation symbols, and a second data subcarrier on the resource unit uses a second modulation scheme to modulate the encoded bits to A second group of modulation symbols; a subcarrier mapper for remapping the first group of modulation symbols to a first half-frequency data subcarrier of the resource unit, and remapping the second group of modulation symbols to A second half-frequency data subcarrier of the resource unit; and a transmitter for sending the resource unit mapped by the subcarrier mapper to a destination station.

It can be known from the above-listed solutions that when the DCM modulation technology is applied in the embodiment of the present invention, the first group of modulation symbols is mapped onto the first half-frequency data subcarrier of a resource unit in a wireless local area network through a subcarrier mapper. The second group of modulation symbols is mapped onto the second half-frequency data subcarrier of the resource unit through the same subcarrier mapper, thereby enhancing transmission reliability based on the DCM mechanism.

Certain terms are used in the description and the scope of subsequent patent applications to refer to specific elements. Those skilled in the art should understand that hardware manufacturers may use different names to refer to the same component. This document does not use the differences in names as a way to distinguish components, but rather uses the functional differences of components as a criterion for distinguishing components. In the following description and the scope of the patent application, the terms "including" and "including" are open-ended terms and should be interpreted as "including but not limited to". In addition, the term "coupled" includes both direct and indirect electrical connections. Therefore, if one device is coupled to another device, it means that the one device can be directly electrically connected to the other device, or indirectly electrically connected to the other device through other devices or connection means.

FIG. 1 illustrates a wireless communication system 100 and a high-efficiency HE PPDU frame structure supporting dual subcarrier modulation (DCM) with low density parity (LDPC) according to a novel aspect. The wireless communication system 100 includes a wireless access point 101 and a wireless station 102. In wireless communication systems, wireless devices communicate with each other through various well-defined frame structures. The frame includes a Physical Layer Convergence Procedure (PLCP) protocol resource unit (Protocol Data Unit, PDU) (abbreviated as: PPDU), a frame header, and a payload. Frames are divided into very specific and standardized parts. In FIG. 1, a high efficiency (HE) PPDU frame 110 is transmitted from a wireless access point 101 to a wireless station 102. HE PPDU 110 includes traditional short training field (shown as: L-STF) 111, traditional long training field (shown as: L-LTF) 112, and traditional signal field (shown as: L- SIG) 113, repeating the traditional signal field (shown as: RL-SIG) 114, high efficiency signal A field (shown as: HE-SIGA) 115, high efficiency signal B field (shown as: : HE-SIGB) 116, high-efficiency short training field (shown as: HE-STF) 117, multiple high-efficiency long training fields for data (shown as: HE-LTF) 118, high Efficiency data payload 119 and packet extension (represented in the figure: PE) 120.

Orthogonal Frequency Division Multiple Access (OFDMA) is introduced in HE WLAN to allow multiple users to transmit data simultaneously to enhance the user experience by allocating a subset of subcarriers to different users. In OFDMA, each user is assigned a set of subcarriers called a resource unit (RU). In HE WLAN, the STA can send a minimum size RU (about 2MHz bandwidth) in the uplink OFDMA. Compared with the 20MHz preamble of the STA, the power density of the data portion of the STA is 9dB higher than its preamble. The narrow-band uplink OFDMA signal is difficult to detect by CCA. Therefore, the subcarrier interference of a STA in a specific narrowband is 9dB higher than that of other subcarriers. It can be seen that narrowband interference is inherent in HE WLAN. Therefore, a solution to deal with narrow-band interference is needed. In addition, in dense deployments, robustness with narrowband interference is important for HW WLAN. Enhancing the Packet Error Rate (PER) performance of the HE data section can extend the range of outdoor scenes. There is a need for a new HE data modulation scheme that can operate at a lower SNR than MCS0.

HE-SIGB is mainly used for prospective users. In multi-user (MU) transmission, the performance of HE-SIGB is encoded using 1x OFDM symbol duration. Finally, when using the same modulation and coding scheme (MCS), its performance is worse than data symbols with 4x OFDM symbol duration. This shows that extending the Cyclic Prefix (CP) from 0.8us (microseconds) to 1.6us or even 3.2us does not effectively ensure that the SIGB is reliable with respect to the data. Therefore, HE-SIGB needs a more robust modulation scheme. HE-SIGB can contain many bits for OFDMA / MU-MIMO transmission. Assume that the HE-SIGB contains information mainly intended for the intended user, and not all other STAs receive the HE-SIGB. The higher the MCS, the higher the efficiency. Therefore, HE-SIGB should allow the use of variable MCS to improve efficiency.

Therefore, dual subcarrier modulation (DCM) is introduced in HE WLAN. DCM is the perfect solution for narrow-band interference. DCM can introduce frequency diversity into OFDM systems by sending the same information on two subcarriers that are separated in frequency. For single-user transmission, the DCM scheme modulates the same information on a pair of data subcarriers n and m, that is, 0 <n <NSD / 2 and m = NSD / 2 + n, where NSD is a data subcarrier in a resource unit. total. For OFDMA transmission, a given user is allocated a frequency resource block. The DCM scheme for one frequency block is the same as the single-user OFDM case.

The DCM indication scheme can be used, making the encoding and decoding of the DCM very simple. As shown in Figure 1, HE-SIGA 115 or HE-SIGB 116 includes an MCS subfield and a DCM bit, where the MCS field is used to indicate MCS and the DCM bit is used to indicate whether to apply DCM to the The user's subsequent HE-SIGB 116 or subsequent data payload 119. If DCM is applied and indicated, the transmitter uses different mapping schemes to modulate the same coded bits on two separate subcarriers. In addition, when a RU is applied to a given RU, a new low density co-located (LDPC) subcarrier mapper can be used. For HE PPDU 110 transmission using DCM, the LDPC coded bit stream is first modulated by the DCM constellation mapper. The modulation symbols in the lower half of the band are repeated, conjugated and mapped to the upper half of the band. The DCM LDPC subcarrier mapper is used to map the modulation symbols in the lower half of the frequency band to the lower half of the data subcarrier. Use the same DCM LDPC subcarrier mapper to map the modulation symbols in the upper half of the band to the upper half of the data subcarrier.

FIG. 2 is a simplified block diagram of a wireless device 201 and 211 (located in a wireless communication system 200) according to a novel aspect. For the wireless device 201 (for example, a transmitting device), the antennas 207 and 208 transmit and receive radio signals. The antenna-coupled RF transceiver module 206 receives RF signals from the antenna, converts them into baseband signals, and sends them to the processor 203. The RF transceiver 206 also converts the baseband signals from the processor, converts them into RF signals, and sends them to the antennas 207 and 208. The processor 203 processes the received baseband signals and calls different function modules and circuits to perform functions in the wireless device 201. The memory 202 stores program instructions and data 210 to control the operation of the device 201.

Similarly, for a wireless device 211 (eg, a receiving device), antennas 217 and 218 transmit and receive RF signals. The RF transceiver module 216 coupled to the antenna receives RF signals from the antenna, converts them to baseband signals, and sends them to the processor 213. The RF transceiver 216 also converts the baseband signal from the processor, converts it to an RF signal, and sends it to the antennas 217 and 218. The processor 213 processes the received baseband signals and calls different function modules and circuits to perform functions in the wireless device 211. The memory 212 stores program instructions and data 220 to control the operation of the wireless device 211.

The wireless devices 201 and 211 also include several functional modules and circuits that can be implemented and configured to perform embodiments of the invention. In the example of FIG. 2, the wireless device 201 is a transmitting device including an encoder 205, a symbol mapper / modulator 204, and an OFDMA module 209. The wireless device 211 is a receiving device and includes a decoder 215, a demapper / demodulator 214, and an OFDMA module 219. Please note that a wireless device can be either a sending device or a receiving device. Different functional modules and circuits can be implemented and configured by software, firmware, hardware and any combination thereof. When the functional modules and circuits are executed by the processors 203 and 213 (for example, by executing the program codes 210 and 220), the transmitting device 201 and the receiving device 211 are allowed to execute the embodiments of the present invention.

In one example, on the transmitter side, the device 201 generates a HE PPDU frame and inserts the MCS and DCM indicator bits into the signal field of the HE PPDU frame at the same time. Then, the device 201 applies the corresponding MCS and DCM and LDPC subcarrier mapping, and sends the HE PPDU to the receiver. On the receiver side, the device 211 receives the HE PPDU and decodes the MCS and DCM indicator bits. If the DCM indication bit is 0, the receiver calculates a Logarithm Likelihood Ratio (LLR) of the received bits of each subcarrier based on the indicated MCS. On the other hand, if the DCM indicator bit is equal to 1, the receiver calculates the LLR by performing the LLR combination of the upper and lower subcarriers of the resource unit. Next, various embodiments of the transmitting device and the receiving device will be described with reference to the drawings.

FIG. 3 is a simplified diagram of a transmission device 300 to which DCM modulation with LDPC subcarrier mapping is applied. The encoder 301 encodes a data packet to be sent to a receiving device, and the encoded bits output by the encoder 301 are fed (can pass a bit interleaver of a BCC not shown) to the DCM + LDPC mapper 302. The encoder 301 may be an LDPC encoder, and therefore, the encoded bits output by the encoder 301 may be LDPC encoded bits. The DCM + LDPC mapper 302 first uses the DCM mapper to modulate the same coded bits on two separate data subcarriers with different mapping schemes. For example, as shown in FIG. 3, the data subcarrier n and the data subcarrier m carry the same bit information, where the data subcarrier n is a lower subcarrier and a mapping scheme # 1 is applied (for example, the following mentioned BPSK), the data subcarrier m is the higher subcarrier, and mapping scheme # 2 is applied (for example, SBPSK mentioned later). The DCM + LDPC mapper 302 then uses the LDPC mapper to remap the modulation symbols formed on the two separate subcarriers to the other data subcarriers of the resource unit. The remapped resource units are fed to the IFFT 303 and sent. .

Assume that the modulation symbols for data subcarrier n and data subcarrier m are expressed as with . For Binary Phase Shift Keying (BPSK) DCM, with It can be obtained by mapping 1-bit coded bits on two identical or different BPSK constellations (for example, BPSK and SBPSK (Shaped Binary Phase Shift Keying)). For example, a BPSK DCM mapping scheme can be:

For QPSK (Quadrature Phase Shift Keying) DCM, with It is possible to map a 2-bit encoded stream on two identical or different QPSK constellations Come to get. E.g, Can use QPSK for mapping, Mapping can be performed using SQPSK (Shaped Quadrature Phase Shift Keying) or other rotated QPSK schemes.

Figure 4 shows an example of a modulation mapping scheme for 16QAM DCM. For 16QAM DCM, by mapping 4-bit streams on two different 16QAM constellations, respectively To get with . As shown in Figure 4, modulation is performed using the constellation shown in Figure 4 (a). And use the constellation diagram shown in 4 (b) to modulate :

among them:

For higher modulation schemes such as 64QAM and 256QAM, the with DCM is applied using two different mapping schemes. For DCM, modulations higher than 16QAM are not recommended. This is because in order to obtain higher performance, DCM may reduce the data rate of higher modulation.

Figure 5 shows the DCM transmission process using LDPC and LDPC subcarrier mappers. The transmitter of the wireless device includes LDPC encoder 501, stream parser 502, selector 511/531, DCM constellation mapper 512/532, DCM LDPC subcarrier mapper 513/533, non-DCM constellation mapper 522/542, LDPC A subcarrier mapper 523/543, a loop shift element delay circuit 534, a spatial mapper 514, and an inverse discrete Fourier transform circuit 515/535 for each stream. The LDPC encoder 501 encodes a data packet into a long bit stream, which is parsed by the stream parser 502 into a plurality of bit streams. If DCM is applied, each bit stream is modulated by the DCM constellation mapper 512 ( ...), and is mapped by the DCM LDPC subcarrier mapper 513. The mapped stream of 513 is further mapped by the spatial mapper 514, and finally passed to the inverse discrete Fourier transform circuit 515 to be transmitted. On the other hand, if DCM is not applied, each bit stream ( ...) modulated by the non-DCM constellation mapper 522 and mapped by the LDPC subcarrier mapper 523, and the mapping result is further mapped by the spatial mapper 514 and passed to the inverse discrete Fourier transform circuit IDFT 515 to be transmitted Out.

Figure 6 shows an example of an LDPC subcarrier mapper when DCM is applied for a given resource unit (RU). In the example in Figure 6, the LDPC coded bit stream ... mapped by the DCM constellation mapper 611, and then by two identical DCM LDPC subcarrier mappers 621 and 622, respectively. NSD is the number of data subcarriers in a resource unit (RU). For LDPC coded bit streams, ..., when DCM modulation is used, the DCM constellation mapper 611 and the DCM LDPC subcarrier mapper 621 and 622 are applied. For example, for QPSK DCM modulation, coded / interleaved bits ... is modulated into QPSK modulation symbols: [d1, d2,… ], The modulation symbol is mapped to the data subcarrier in the lower half of the resource unit; the modulation symbol in the lower half is repeated and conjugated [ , ,… ] = conj ([d1, d2,… ]), And then mapped to the data subcarrier in the upper half of the resource unit. Then use DCM LDPC subcarrier mapper 621 to convert [d1, d2,… ] Remap to the data subcarriers [1,2, ... NSD / 2] and use the same DCM LDPC subcarrier mapper 622 to [ , ,… ] Remapping to the data subcarriers [NSD / 2 + 1, NSD / 2 + 2,… NSD]. The DCM LDPC subcarrier mappers 621 and 622 are the same.

In a next-generation WLAN system based on the upcoming IEEE 801.11ax standard, each station (STA) can use one or more resource units (RU) to transmit signals. The RU size can be 26, 52, 106, 242, 484 or 996 subcarriers (including pilot subcarriers and data subcarriers), and the subcarrier spacing is approximately 78.1kHz. Correspondingly, the number of data subcarrier NSDs of each RU is 24, 48, 102, 234, 468, and 980, respectively. When a DCM is applied to a given RU, the number of modulation symbols generated by the DCM using a given stream is half the number of data subcarriers and subcarriers of the RU, that is, NSD / 2. For example, if the size of the data subcarrier of the RU is 102, the number of modulation symbols generated using the DCM is NSD / 2 = 51. The generated modulation symbols will be mapped onto the data subcarriers of the first and second half bands of the RU (for example, in Figure 6, for QPSK DCM modulation, the coded / interleaved bits ... is modulated into QPSK modulation symbols: [d1, d2,… ], The modulation symbol is mapped to the data subcarrier in the lower half of the resource unit; the modulation symbol in the lower half is repeated and conjugated [ , ,… ] = conj ([d1, d2,… ]), And then mapped to the data subcarrier in the upper half of the resource unit. Then use DCM LDPC subcarrier mapper 621 to convert [d1, d2,… ] Remap to the data subcarriers [1,2, ... NSD / 2] and use the same DCM LDPC subcarrier mapper 622 to [ , ,… ] Re-mapped to the data subcarriers [NSD / 2 + 1, NSD / 2 + 2,… NSD]). The first half of the RU contains subcarriers 1 to NSD / 2, and the second half of the RU contains subcarriers NSD / 2 to subcarrier NSD, where NSD is the size of the RU's data on the carrier.

Figure 7 shows one embodiment of an LDPC subcarrier mapper for DCM. For HE PPDU transmission without DCM, the LDPC subcarrier mapping corresponding to the LDPC coded stream of user u in the r-th RU is accomplished by replacing the modulation symbols generated by the constellation mapper as follows, where NSD is the r-th The total number of data subcarriers in the RU.

As described below, the LDPC subcarrier mapper maps the kth modulation symbol generated by the constellation mapper to the t (k) th subcarrier, where DTM is the LDPC subcarrier mapping distance of the rth RU.

For HE PPDU transmission with DCM, the LDPC subcarrier mapping of the LDPC-encoded stream corresponding to user u in the rth RU is accomplished by replacing the modulation symbol stream generated by the constellation mapper as follows, NSD is the total number of data subcarriers in the r-th RU.

As described below (see Figure 6), the DCM LDPC subcarrier mapper maps the kth modulation symbol generated by the constellation mapper to the t (k) th subcarrier, where DTM-DCM is the rth RU when DCM is applied LDPC subcarrier mapping distance.

In the example of table 700, DCM LDPC subcarrier mapping will be performed on all LDPC encoded streams mapped into the RU as described above. When DCM is applied to the LDPC coded stream, DTM-DCM should be applied to the lower half of the data subcarriers in the RU and the upper half of the data subcarriers in the RU. For each RU size, the LDPC subcarrier mapping distance parameters DTM and DTM-DCM are constant, and the values of DTM and DTM-DCM for different RU sizes are given in Table 700. The LDPC subcarrier mapper guarantees that every two consecutively generated modulation symbols will be transmitted on two subcarriers separated by at least other data subcarriers (for example, DTM-DCM-1). Each DTM-DCM corresponds to a different LDPC subcarrier mapper (equivalent to a block interleaver).

The two frequency subcarriers for the DCM can be predetermined. For single-user transmission, for example, DCM modulation can be applied to subcarriers k and k + N / 2, where N is the total number of subcarriers in one OFDM symbol or one RU. For OFDMA transmission, DCM modulation can be applied to two equal-frequency resource blocks allocated to a given user. Even if interference in one frequency band or frequency resource block is used, a transmission method using DCM can be realized. For example, for non-WiFi signals or overlapping Basic Service Set (OBSS) signals, different clear channel assessment (CCA) thresholds can be applied to the two frequency bands.

FIG. 8 is a simplified diagram of a receiving device 800 using DCM with LDPC demapping. At the receiver, the received signal through the fast Fourier transform module 801 can be written as:

--- Upper subcarrier

--- Sub-carrier

among them:

with Is the channel response matrix of subcarriers n and m;

with It is modeled as additive Gaussian white noise (AWGN) noise.

When the SNRs of the upper and lower subcarriers are considered to be "good", the receiver's demapper / demodulator 802 can calculate the log-likelihood ratio of the received bits by combining the received signals from the upper and lower subcarriers ( LLR). Alternatively, when the SNRs of the upper and lower subcarriers are considered to be "bad", the receiver may choose to calculate the LLR of only the received bits from the upper subcarrier or select the LLR of only the received bits from the lower subcarrier. The demodulated signal is then fed to a decoder 803 to output a decoded signal.

There are many advantages to using DCM. No delay for modulation is added within one OFDM symbol. No additional complexity is introduced on the modulator and demodulator. For modulation, there is no additional complexity, just the upper band subcarriers and the lower band subcarriers need to be modulated in a similar manner. For demodulation, the LLR calculation is very simple. For QPSK, just add two LLRs. For 16QAM, only a few simple additional subtractions are required. Simulation results show that for MCS0 and MCS2, PER performance improves at least 2dB gain in 4x symbols. This performance gain is significant. For wider bandwidths (> 20MHz), greater performance gains can be expected based on larger frequency diversity gains. For outdoor access, false leveling is also reduced. Overall, the DCM scheme results in stronger robustness to narrowband interference and provides a very good compromise between data rate and QPSK½ rate code and 16QAM½ rate.

FIG. 9 is a flowchart of a method of transmitting and encoding a HE PPDU frame using a DCM with LDPC subcarrier mapping according to a novel aspect. In step 901, the source station encodes a data packet to be sent to the destination station. In step 902, when dual subcarrier modulation (DCM) is applied, the source station uses different modulation schemes to modulate the encoded information on two separate subcarriers of the resource unit to generate a first set of modulation symbols. And the second set of modulation symbols, for example, the two separated subcarriers are respectively located in the first half-frequency data subcarrier range and the second half-frequency data subcarrier range of the resource unit; in step 903, the source The station remaps the first group of modulation symbols to the first half-frequency data subcarrier of the resource unit through a subcarrier mapper, and remaps the second group of modulation symbols to On the second half-frequency data subcarrier of the resource unit; in specific implementation, the remapping can ensure that every two consecutively generated modulation symbols will be transmitted on two subcarriers separated by at least other data subcarriers. In step 904, the source station sends the resource units mapped by the subcarrier mapper to the destination station. In one example, the subcarrier mapper is a low density parity (LDPC) subcarrier mapper designed for dual subcarrier modulation.

The use of ordinal numbers such as "first" and "second" in the scope of the patent application does not imply any priority, order of priority, order between elements, or chronological order of executed methods, and Used only as an identifier to distinguish between different components with the same name (with different ordinal numbers). The above description is only a preferred embodiment of the present invention, and all equivalent changes and modifications made in accordance with the scope of patent application of the present invention shall fall within the scope of the present invention.

100, 200‧‧‧ wireless communication system

101‧‧‧Wireless access point

110‧‧‧High Efficiency (HE) PPDU Frame

102‧‧‧Wireless Station

111‧‧‧ traditional short training field

112‧‧‧Traditional Long Training Field

113‧‧‧ Traditional Signal Field

114‧‧‧ Repeat traditional signal field

115‧‧‧High Efficiency Signal A

116‧‧‧High efficiency signal B field

117‧‧‧High efficiency short training field

118‧‧‧ Efficient long training field for data

119‧‧‧High Efficiency Data Payload

120‧‧‧Group expansion

201, 211‧‧‧ wireless equipment

203, 213‧‧‧ processors

202, 212‧‧‧Memory

210, 220‧‧‧ program instructions and information

206,216‧‧‧RF transceiver

205, 301‧‧‧ encoder

204‧‧‧Symbol Mapper / Modulator

209,219‧‧‧OFDMA module

207,208,217,218‧‧‧antenna

215,803‧‧‧ decoder

214,802‧‧‧‧Demap / Demodulator

300‧‧‧ sending equipment

302‧‧‧DCM / LDPC block

303‧‧‧IFFT

501‧‧‧LDPC encoder

502‧‧‧stream parser

511,531‧‧‧ selector

512, 532, 611‧‧‧DCM Constellation Mapper

522, 542‧‧‧ non-DCM constellation mapper

513,533,621,622‧‧‧‧DCM LDPC subcarrier mapper

523,543‧‧‧LDPC Subcarrier Mapper

534‧‧‧Circular shift element delay circuit for each stream

514‧‧‧Space Mapper

515,535‧‧‧‧Inverse discrete Fourier transform circuit

700‧‧‧ watch

800‧‧‧ receiving equipment

801‧‧‧Fast Fourier Conversion Module

901, 902, 903, 904 ‧‧‧ steps

FIG. 1 illustrates a wireless communication system 100 and a high-efficiency HE PPDU frame structure supporting dual subcarrier modulation (DCM) with low density parity (LDPC) according to a novel aspect; FIG. 2 illustrates a wireless device according to a novel aspect Simplified block diagrams of 201 and 211; Figure 3 is a simplified diagram of a transmitting device 300 applying DCM modulation with LDPC subcarrier mapping; Figure 4 shows an example of a modulation mapping scheme for 16QAM DCM; Figure 5 DCM transmission process using LDPC and LDPC subcarrier mapper is shown; FIG. 6 shows an example of LDPC subcarrier mapper when DCM is applied for a given resource unit (RU); FIG. 7 shows One embodiment of an LDPC subcarrier mapper for DCM; FIG. 8 is a simplified diagram of a receiving device 800 using DCM with LDPC de-modulation; FIG. 9 is a diagram using LDPC subcarrier mapping according to a novel aspect Flow chart of a method for DCM to send and encode HE PPDU frames.

Claims (19)

A method for transmitting a data packet through a resource unit in a wireless local area network, comprising: encoding a data packet to be sent from a source station to a destination station; and if dual subcarrier modulation is applied, using the first data subcarrier on the resource unit A modulation scheme that modulates the encoded bits to a first group of modulation symbols, and uses a second modulation scheme to modulate the encoded bits to a second group of modulation symbols on a second data subcarrier of the resource unit; A subcarrier mapper remaps the first group of modulation symbols to a first half-frequency data subcarrier of the resource unit, and remaps the second group of modulation symbols to the resource unit through the same subcarrier mapper A second half-frequency data subcarrier of the resource unit; and sending the resource unit mapped by the subcarrier mapper to the destination station. According to the method described in item 1 of the patent application scope, the first modulation scheme and the second modulation scheme are based on the same modulation order. According to the method according to item 1 of the scope of patent application, the first data subcarrier is located in a first half-frequency resource subcarrier range of the resource unit, and the second data subcarrier is located in a second half of the resource unit. Within half-frequency resource subcarrier range. According to the method described in item 1 of the patent application scope, the number of modulation symbols generated by the first and second modulation schemes is half of the total number of data subcarriers contained in the resource unit. According to the method described in item 1 of the patent application scope, the subcarrier mapper is used for low-density co-channel control coding. According to the method described in claim 5 of the patent application scope, the low-density co-channel subcarrier mapper maps each modulation symbol generated by the first modulation scheme to the first half-frequency data belonging to the resource unit. Subcarrier. According to the method described in claim 5 of the patent application scope, the low-density co-channel subcarrier mapper maps each modulation symbol generated by the second modulation scheme to the second half-frequency data belonging to the resource unit Subcarrier. According to the method described in item 5 of the patent application scope, the low-density co-channel subcarrier mapper is a block interleaver with a constant distance for each resource unit size. According to the method described in item 5 of the scope of the patent application, the low-density co-channel subcarrier mapping distance when dual subcarrier modulation is applied is different from the low-density co-channel subcarrier mapping distance when dual subcarrier modulation is not applied. The method according to item 1 of the scope of patent application, further comprising: determining whether to apply dual subcarrier modulation to the encoded bits; and performing non-modulation if dual subcarrier modulation is not applied to the encoded bits. Dual subcarrier modulation and subcarrier mapping. A wireless station that sends a data packet through a resource unit in a wireless local area network includes: an encoder for encoding a data packet to be sent from a source station to a destination station; a modulator, if dual subcarrier modulation is applied, at the resource unit Using the first modulation scheme on the first data subcarrier to modulate the encoded bits to a first set of modulation symbols, and using the second modulation scheme on the second data subcarrier of the resource unit to encode the bits Modulation to a second group of modulation symbols; a subcarrier mapper for remapping the first group of modulation symbols to a first half-frequency data subcarrier of the resource unit, and re-modulating the second group of modulation symbols Mapped to the second half-frequency data subcarrier of the resource unit; and a transmitter for sending the resource unit mapped by the subcarrier mapper to a destination station. According to the wireless station according to item 11 of the scope of patent application, the first modulation scheme and the second modulation scheme are based on the same modulation order. According to the wireless station according to item 11 of the scope of patent application, the first data subcarrier is located within a first half-frequency resource subcarrier of the resource unit, and the second data subcarrier is located within a first half of the resource unit. Within the second half-frequency resource subcarrier range. According to the wireless station according to item 11 of the scope of patent application, the number of modulation symbols generated by the first and second modulation schemes is half of the total number of data subcarriers contained in the resource unit. According to the wireless station according to item 11 of the scope of patent application, the subcarrier mapper is used for low-density co-channel control coding. According to the wireless station according to item 15 of the scope of patent application, the low-density co-channel subcarrier mapper maps each modulation symbol generated by the first modulation scheme to the first half-frequency belonging to the resource unit Data subcarriers. According to the wireless station of claim 15 in the patent application scope, the low-density co-channel subcarrier mapper maps each modulation symbol generated by the second modulation scheme to the second half-frequency belonging to the resource unit Data subcarriers. According to the wireless station according to item 15 of the scope of the patent application, the low-density co-channel subcarrier mapper is a block interleaver having a constant distance for each resource unit size. According to the wireless station described in item 15 of the scope of the patent application, the low-density co-channel sub-carrier mapping distance when dual sub-carrier modulation is applied is different from the low-density co-channel sub-carrier mapping distance when dual sub-carrier modulation is not applied.