Communication device and communication method using dual-stream dual-carrier modulation

Abstract

The present disclosure provides a communication apparatus and a communication method related to dual-stream dual-carrier modulation (DCM). The communication apparatus, during operation, includes a circuit configured to set first information indicating whether mapping of two or more modulation symbols modulated from information bits of a signal to two or more subcarriers is applied across two or more spatial streams of an orthogonal frequency division multiplexing (OFDM) symbol, and second information indicating whether data rate adjustment is applied to the signal, and a transmission unit configured to transmit a signal including the first information and the second information by using mapping of two or more modulation symbols across two or more spatial streams and / or data rate adjustment during operation.

Description

Technical Field

[0001] The present disclosure relates to a communication device and method for sub-carrier modulation, and particularly to sub-carrier modulation across multiple spatial streams.

Background Art

[0002] The Dual Carrier Modulation (DCM) scheme is a modulation scheme with frequency diversity, which reduces the data rate, expands the communication range, and particularly reduces the Packet Error Rate (PER) when interference exists.

[0003] According to the draft of 802.11be Extremely High Throughput, DCM is only applicable to Binary Phase Shift Keying (BPSK), rate 1 / 2 coding, and single spatial stream (SS) non-multi-user multiple input and multiple output (non-MU-MIMO) transmission. Extending DCM to two or more spatial streams is a good way to add spatial diversity to transmission. However, when using two or more spatial streams, the communication range and transmission reliability decrease.

[0004] Therefore, there is a need for a communication device and method for carrier (or sub-carrier) modulation to address these problems, and in particular, to extend sub-carrier modulation across two or more spaces, space-time, space-frequency, or transmission streams to support multi-stream transmission.

[0005] Furthermore, other desirable features and characteristics will become apparent from the following detailed description and the appended claims, in conjunction with the accompanying drawings and the background of the present disclosure.

Summary of the Invention

[0006] Non-limiting exemplary embodiments facilitate providing a communication device and a communication method for subcarrier modulation over multiple spatial streams in the context of a WLAN.

[0007] In a first aspect, the present disclosure provides a first communication device comprising: a circuit configured to set, during operation, first information indicating whether mapping of two or more modulation symbols modulated from information bits of a signal to two or more subcarriers is applied over two or more spatial streams of an orthogonal frequency division multiplexing (OFDM) symbol, and second information indicating whether data rate adjustment is applied to the signal; and a transmission unit configured to transmit, during operation, the signal including the first information and the second information by using the mapping of the two or more modulation symbols over the two or more spatial streams and / or the data rate adjustment.

[0008] In a second aspect, the present disclosure provides a second communication device comprising: a reception unit configured to receive, during operation, a signal including first information indicating whether mapping of two or more modulation symbols modulated from information bits of a signal to two or more subcarriers is applied over two or more spatial streams of an OFDM symbol, and second information indicating whether data rate adjustment is applied to the signal; and a circuit configured to decode and demodulate the signal to obtain information on the information bits mapped over the two or more spatial streams.

[0009] In a third aspect, the present disclosure provides a communication method performed by a first communication device, the method including: setting first information indicating whether mapping of two or more modulation symbols modulated from information bits of a signal to two or more subcarriers is applied over two or more spatial streams of an OFDM symbol, and second information indicating whether data rate adjustment is applied to the signal; and transmitting the signal including the first information and the second information by using the mapping of the two or more modulation symbols and / or the data rate adjustment.

[0010] In a fourth aspect, the present disclosure provides first information indicating whether mapping two or more modulation symbols modulated from information bits of a signal to two or more subcarriers is applied across two or more spatial streams of an OFDM symbol, and receiving the signal including second information indicating whether data rate adjustment is applied to the signal; and decoding and demodulating the signal to obtain information on the information bits mapped to the two or more spatial streams. A communication method performed by a second communication device, including:

[0011] Note that a general embodiment or a specific embodiment can be implemented as a system, a method, an integrated circuit, a computer program, a storage medium, or any optional combination thereof.

[0012] Further advantages and effects in an embodiment of the present disclosure will be apparent from the specification and the drawings. Such advantages and / or effects are provided by some embodiments and the features described in the specification and the drawings respectively, but not necessarily all are provided to obtain one or more identical features.

[0013] Embodiments of the present disclosure are merely examples, and will be better understood and will become readily apparent to those skilled in the art from the following description in conjunction with the drawings.

Brief Description of the Drawings

[0014]

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[0015] Those skilled in the art can understand that the elements in the figures are described simply and clearly and are not necessarily drawn to scale. For example, the dimensions of some elements in the illustrations, block diagrams, or flowcharts may be exaggerated relative to other elements for the purpose of accurately understanding the current embodiments.

[0016] Some embodiments of the present disclosure will be described by way of example with reference to the drawings. Like reference numerals and letters in the drawings refer to like or equivalent elements.

[0017] In the following paragraphs, specific exemplary embodiments are described with reference to access points (APs) and stations (STAs) for subcarrier modulation across multiple spatial streams, particularly in multiple-input multiple-output (MIMO) wireless networks.

[0018] In the context of IEEE802.11 (Wi-Fi) technology, a station, also called an STA, is a communication device that can use the 802.11 protocol. Based on the definition of IEEE802.11-2016, an STA can be any device that has a medium access control (MAC) and a physical layer (PHY) interface compliant with IEEE802.11 with respect to a wireless medium (WM).

[0019] For example, an STA may be a laptop, a desktop personal computer (PC), a personal digital assistant (PDA), an access point, or a Wi-Fi phone in a wireless local area network (WLAN) environment. An STA may be stationary or mobile. In a WLAN environment, the terms "STA", "wireless client", "user", "user device", and "node" are often used interchangeably.

[0020] Similarly, an AP, which can also be called interchangeably a wireless access point (WAP) in the context of IEEE802.11 (Wi-Fi) technology, is a communication device that enables the connection of an STA in a WLAN to a wired network. An AP is usually connected to a router (via a wired network) as a stand-alone device, but may be integrated with the router or used within the router.

[0021] As described above, an STA in a WLAN can operate as an AP in other cases, and vice versa. This is because a communication device in the context of IEEE802.11 (Wi-Fi) technology may include both STA hardware components and AP hardware components. Thus, the communication device may switch between STA mode and AP mode based on the actual WLAN conditions and / or requirements.

[0022] In a MIMO wireless network, "multiple" refers to multiple antennas that are simultaneously used for transmission and multiple antennas that are simultaneously used for reception via a wireless channel. In this regard, "multiple-input" refers to multiple transmitter antennas that input a wireless signal into a channel, and "multiple-output" refers to multiple receiver antennas that receive a wireless signal from the channel to a receiver. For example, in an N×M MIMO network system, N is the number of transmitter antennas, M is the number of receiver antennas, and N may or may not be equal to M. For the sake of simplicity, the respective numbers of transmitter antennas and receiver antennas will not be further described in this disclosure.

[0023] In a MIMO wireless network, single-user (SU) communication and multi-user (MU) communication can be carried out for communication between communication devices such as APs and STAs. The MIMO wireless network has advantages such as spatial multiplexing and spatial diversity, which enable higher data rates and robustness through the use of multiple spatial streams.

[0024] In the various embodiments below, "channel" and "subchannel" can be used interchangeably with any of "band", "subband", and "frequency segment".

[0025] FIG. 1 shows a schematic diagram of SU communication 100 between AP _{102} and STA _{104} in a MIMO wireless network. As shown, the MIMO wireless network may include one or more STAs (e.g., STA _{104}, STA _{106}, etc.). When the SU communication 100 within a channel is executed over the entire channel bandwidth, it is called full bandwidth SU communication. When the SU communication 100 within a channel is executed over a part of the channel bandwidth (e.g., when one or more 20 MHz sub-channels within the channel are punctured), it is called punctured SU communication. In SU communication 100, AP _{102} uses a plurality of antennas (e.g., four antennas as shown in FIG. 1) to transmit a plurality of spatio-temporal streams using all the spatio-temporal streams directed to a single communication device, i.e., STA _{104}. For simplicity, the plurality of spatio-temporal streams directed to STA _{104} are shown as grouped data transmission arrows 108 directed to STA _{104}.

[0026] SU communication 100 can be configured for two-way transmission. As shown in FIG. 1, in SU communication 100, STA _{104} may use a plurality of antennas (e.g., two antennas as shown in FIG. 1) to transmit a plurality of spatio-temporal streams using all the spatio-temporal streams directed to AP _{102}. For simplicity, the plurality of spatio-temporal streams directed to AP _{102} are shown as grouped data transmission arrows 110 directed to AP _{102}.

[0027] Therefore, in the SU communication 100 shown in FIG. 1, both uplink and downlink SU transmissions in the MIMO wireless network are possible.

[0028] FIG. 2 is a schematic diagram showing downlink multiple-user (MU) communication 200 between an AP 202 and a plurality of STAs 204, 206, 208 in a MIMO wireless network. The MIMO wireless network may include one or more STAs (e.g., STAs 204, STA 206, STA 208, etc.). The MU communication 200 can be OFDMA (Orthogonal Frequency Division Multiple Access) communication or MU-MIMO communication. In the case of OFDMA communication in a channel, the AP 202 simultaneously transmits a plurality of streams to the STAs 204, 206, 208 in the network on different resource units (RUs) within the channel bandwidth. In the case of MU-MIMO communication in a channel, the AP 202 uses a plurality of antennas via spatial mapping or precoding techniques to simultaneously transmit a plurality of streams to the STAs 204, 206, 208 on the same one or more RUs within the channel bandwidth. When the RUs for OFDMA communication or MU-MIMO communication occupy the entire channel bandwidth, the OFDMA communication or MU-MIMO communication is called full-bandwidth OFDMA communication or full-bandwidth MU-MIMO communication. When the RUs for OFDMA communication or MU-MIMO communication occupy a part of the channel bandwidth (e.g., when one or more 20 MHz sub-channels within the channel are punctured), the OFDMA communication or MU-MIMO communication is called punctured OFDMA communication or punctured MU-MIMO communication. For example, two space-time streams can be directed to STA 206, another one space-time stream can be directed to STA 204, and still another one space-time stream can be directed to STA 208. For simplicity, the two space-time streams directed to STA 206 are shown as grouped data transmission arrows 212, the space-time stream directed to STA 204 is shown as a data transmission arrow 210, and the space-time stream directed to STA 208 is shown as a data transmission arrow 214.

[0029] To enable uplink MU transmission, trigger-based communication is provided to the MIMO wireless network. In this regard, FIG. 3 shows a schematic diagram of trigger-based (TB) uplink MU communication 300 between an AP 302 and a plurality of STAs 304, 306, 308 in the MIMO wireless network.

[0030] Since there are a plurality of STAs 304, 306, 308 participating in the trigger-based uplink MU communication, the AP 302 needs to coordinate the simultaneous transmission of the plurality of STAs 304, 306, 308.

[0031] For coordination, as shown in FIG. 3, the AP 302 simultaneously transmits trigger frames 310, 314, 318 to the STAs 304, 306, 308 to indicate user-specific resource allocation information (e.g., the number of spatio-temporal streams, the starting STS number, and the allocated RUs) that each STA can use. Then, in response to the trigger frames, the STAs 304, 306, 308 may simultaneously transmit their respective spatio-temporal streams to the AP 302 according to the user-specific resource allocation information indicated in the trigger frames 310, 314, 318. For example, two spatio-temporal streams may be directed from the STA 306 to the AP 302, another one spatio-temporal stream may be directed from the STA 304 to the AP 302, and yet another one spatio-temporal stream may be directed from the STA 308 to the AP 302. For simplicity, the two spatio-temporal streams directed from the STA 306 to the AP 302 are shown as a grouped data transmission arrow 316, the spatio-temporal stream directed from the STA 304 to the AP 302 is shown as a data transmission arrow 312, and the spatio-temporal stream directed from the STA 308 to the AP 302 is shown as a data transmission arrow 320.

[0032] Packet / PPDU (Physical Layer Protocol Data Unit)-based transmission is performed by the Enhanced Distributed Channel Access (EDCA) mechanism and the distributed MAC (Media Access Control) method of 802.11 WLAN, so frequency and spatial resource scheduling is performed on a packet basis. In other words, the resource allocation information is PPDU-based in the EDCA mechanism.

[0033] WLAN supports non-trigger-based communication shown in FIGS. 1 and 2 and trigger-based communication shown in FIG. 3. In non-trigger-based communication, a communication device transmits a PPDU to one other communication device or two or more other communication devices in an unsolicited manner. In trigger-based communication, a communication device transmits a PPDU to one other communication device or two or more other communication devices only when it receives a request of a trigger frame.

[0034] As described above, the DCM method is a modulation method by frequency diversity for reducing the data rate, expanding the communication range, and reducing the packet error rate (PER), especially when interference exists. FIG. 4 shows a block diagram 400 showing the DCM method applied to information bits from the spatial stream (SS) of an orthogonal frequency division multiplexing (OFDM) symbol. In a typical DCM method, information bits from a spatial stream are modulated into two modulation symbols using different modulation mappings, that is, mapped to a pair of subcarriers (m, n) within an OFDM symbol. According to 802.11be EHT, the DCM method is applicable only to a single spatial stream. The pair of subcarriers (m, n) are usually widely separated frequency-wise within a spatial stream (e.g., separated by N SD / 2. Here, N SD is the number of data subcarriers per OFDM symbol or the number of data subcarriers within a subband (e.g., 20 / 40 / 80 MHz subband)).

[0035] FIG. 5 shows a transmission block diagram 500 illustrating the processing of a data field using a typical DCM scheme. The data field can be composed of the following processing blocks. The processing in the transmitter starts with a Pre-Forward Error Correction (FEC) physical layer (PHY) padding unit that adds redundant information to the data bits before the data is output to a scrambler that scrambles the data bits to reduce long runs of the same bit. A Low-Density Parity-Check (LDPC) encoder unit encodes the data bits before the encoded data is output to an FEC post-PHY padding unit that adds padding bits to match the number of bits required for the symbols.

[0036] Next, a stream parser unit divides the encoded bits into multiple blocks and transmits them through multiple spatial streams (N SS where N is the number of spatial streams). Here, N SS is 1, indicating a single spatial stream. The single spatial stream corresponds to a block of encoded bits and is transmitted to a constellation mapper unit and an LDPC tone mapper unit. The constellation mapper unit maps each block of encoded bits to a constellation point or complex number (also referred to here as a modulation symbol) using a selected modulation scheme (in this case, BPSK and DCM), maps each modulation symbol to two OFDM subcarriers (DCM), and ensures that each OFDM subcarrier is sufficiently separated in frequency to maximize the gain of frequency diversity. The LDPC tone mapper unit further interleaves the modulation symbols within the OFDM symbol to better protect against burst errors and overcome frequency-selective fading.

[0037] Thereafter, the spatial stream is sent to a spatial mapper unit for mapping to a plurality of transmit chains (three transmit chains are shown, each indicated by an arrow pointing from the spatial mapper unit). Each transmit chain is sent to an Inverse Discrete Fourier Transform (IDFT) unit. Each IDFT unit converts the OFDM subcarriers (frequency domain data) on the transmit chain into time domain data for transmission. The time domain data of the IDFT unit is then sent to a Guard Interval (GI) insertion and windowing unit, where a GI is inserted at the start of each OFDM symbol of the transmit chain, and each OFDM symbol may be windowed to minimize adjacent channel interference. The time domain data of each transmit chain is then sent to an analog and radio frequency (RF) unit, which prepares the data for transmission through an antenna.

[0038] In the 802.11be EHT draft, DCM is applicable to EHT Modulation Coding Scheme (MCS) 14 and EHT-MCS15. In EHT-MCS14, BPSK, rate 1 / 2 coding scheme, DCM, and Duplicate (DUP) mode are applicable. On the other hand, in EHT-MCS15, BPSK, rate 1 / 2 coding scheme, and DCM are applicable. The EHT DUP mode is a mode in which the transmitted data in the payload part of the PPDU is replicated at a frequency of 1 / 2. The EHT DUP mode can reduce the data rate in the 6 GHz band with wide bandwidths of 80 / 160 / 320 MHz.

[0039] Figure 6 shows the replicated data in the payload parts of the 80 / 160 MHz PPDU 600 and 320 MHz PPDU 620. In the 80 / 160 MHz PPDU, in the payload part, symbols X and X modulated from the same information bits via the DCM method in 40 / 80 MHz frequency segments DCMIt can include, and can also include, via the DUP mode, a replication (based on 1 / 2 of the frequency) of symbols modulated in the remaining 40 / 80 MHz frequency segment. The replication may include a phase rotation in one or more of the replicated symbols. In this case, the modulated symbol X is shifted to -X during replication. Similarly, in a 320 MHz PPDU, in the payload part, there are symbols X and X modulated from the same information bits via the DCM method in the 160 MHz frequency segment DCM and symbol X generated from L X L,DCM X U and X U,DCM can be included. Here, symbol X L is the lower half of symbol X, symbol X U is the upper half of symbol X, symbol X L,DCM is the lower half of symbol X DCM and symbol X U,DCM is the upper half of symbol X DCM . In the payload part, a replication (based on 1 / 2 of the frequency) of symbols modulated in the remaining 160 MHz frequency segment is also included via the DUP mode.

[0040] Figure 7 shows a transmission block diagram 700 showing the processing of a data field using typical DCM and DUP modes. The processing of the transmission part is similar to that shown in Figure 5 which processes a single spatial stream using an FEC pre-PHY padding unit, a scrambler unit, an LDPC encoder unit, an FEC post-PHY padding unit, a stream parser unit (N SS = 1), a constellation mapper unit, and an LDPC tone mapper unit. However, after the LDPC tone mapper unit, the spatial stream is sent to a frequency domain replication unit where the modulated symbols on the spatial stream are replicated (e.g., based on 1 / 2 of the frequency), and then sent to a spatial mapper unit for mapping to multiple transmission chains.

[0041] In 802.11ax HE, DCM is only applicable to HE-MCS 0, 1, 3, and 4, and the maximum number of spatial streams is 2. In the case of 2 spatial streams, the same modulation principle applied to a single spatial stream is applied to each spatial stream. This enables only frequency diversity gain.

[0042] FIG. 8 shows a block diagram 800 illustrating the DCM scheme applied to two information bits across two spatial streams (SS1, SS2) of an OFDM symbol. Conventionally, the same modulation principle is applied to two information bits X1, X2 from different spatial streams (SS1, SS2). In particular, each of the information bits X1, X2 is mapped to a pair of symbols (X 1k and X 1kDCM , X 2k and X 2kDCM ) that are mapped to a pair of subcarriers (m, n) within an OFDM symbol in their respective spatial streams (SS1, SS2). Similarly, the pair of subcarriers (m, n) are widely separated in frequency within the spatial stream (e.g., separated by N SD / 2, where N SD is the number of data subcarriers per OFDM symbol or the number of data subcarriers within a subband (e.g., 20 / 40 / 80 MHz subband)).

[0043] In contrast to DCM, the space-frequency diversity scheme (SFDS) is applied across two spatial streams. An example of SFDS is space frequency block coding (SFBC). FIG. 9 shows a block diagram 900 illustrating the SFBS scheme applied to two information bits across two spatial streams (SS1, SS2) of an OFDM symbol. In particular, the information bit from the first spatial stream (SS1) is modulated into two modulated symbols X 1k , X 1k * mapped to a pair of subcarriers (m, n). One of the modulated symbols (e.g., X1k ) is mapped to a first sub - carrier (m) corresponding to a first spatial stream (SS1), and another modulation symbol (e.g., X 1k * ) is mapped to a second sub - carrier (n) corresponding to a second spatial stream (SS2). Another information bit from the second spatial stream is also mapped to two modulation symbols X 2k , X 2k * modulated to. One of the modulation symbols (e.g., X 2k ) is mapped to the first sub - carrier (m) corresponding to the second spatial stream (SS2), and another modulation symbol (e.g., X 2k * ) is mapped to the second sub - carrier (n) corresponding to the first spatial stream (SS1). The pair of sub - carriers (m, n) are widely separated in frequency within the spatial stream (e.g., separated by N SD / 2, where N SD is the number of data sub - carriers per OFDM symbol or the number of data sub - carriers within a sub - band (e.g., 20 / 40 / 80 MHz sub - band)). In addition to the frequency diversity gain, such an SFDS scheme also enables a spatial diversity gain. In a modulation scheme including the SFDS scheme, if each formed stream (e.g., SS1 / SS2) contains the same (or overlapping) set of information bits (e.g., X1, X2), the stream may be called, for example, a spatial - frequency stream or a transmission stream, or a spatial stream.

[0044] As described above, in 802.11be EHT, the DCM method is applicable only to single spatial stream transmission. Extending DCM to two or more spatial streams is a good way to add spatial diversity to transmission. However, using multiple spatial streams reduces the communication range and transmission reliability. Therefore, there is a need for a communication device and method for carrier (or sub-carrier) modulation to address these problems, and in particular, it is necessary to extend sub-carrier modulation across two or more spatial streams to support multiple spatial stream transmissions.

[0045] According to the present disclosure, the extended frequency diversity method is applied to two or more spatial streams, providing higher or additional diversity gains (e.g., spatial diversity and / or antenna diversity) compared to the DCM of the 802.11 specification. Additionally or alternatively, a reliability improvement method that reduces the data rate to improve transmission reliability and provides additional diversity gains is applied.

[0046] In the following various embodiments, the extended frequency diversity method refers to mapping two or more modulation symbols modulated from the information bits of a signal to two or more sub-carriers. On the other hand, the reliability improvement method refers to the adjustment of the data rate.

[0047] The application of the extended frequency diversity method, i.e., mapping two or more modulation symbols modulated from the information bits of a signal to two or more sub-carriers, and the reliability improvement method, i.e., the adjustment of the data rate, are indicated through the first information and the second information set by the transmitting side AP (or STA), respectively. In one implementation, the application of the extended frequency diversity method is indicated by the number of spatial streams (N SS ) and the MCS information in the preamble part of the signal. The extended frequency diversity method (e.g., extended DCM method) can be a predefined method known to the intended receiving side or a method explicitly indicated in the preamble part of the signal.

[0048] For example, in an EHT MU PPDU, when MCS15 is indicated in the User field of the EHT-SIG field of the PPDU, if the SS (number of spatial streams) field is 1 (the same as 802.11be), the conventional DCM method is notified. SS If the field is 2 (N SS =2 is reserved in 802.11be), the extended DCM method is notified.

[0049] Also, in future implementations and revisions, such an application of the extended frequency diversity method may be indicated only by the MCS information.

[0050] Similarly, the application of the reliability improvement method can be set as the default together with the extended frequency diversity method, or can be notified by the N SS preamble part of the signal and the MSC information.

[0051] For example, in an EHT MU PPDU, when MCS15 and 3 are indicated in the User field of the EHT-SIG field of the PPDU, an extended DCM method with reliability improvement is indicated. SS When this is shown, an extended DCM method with reliability improvement is shown.

[0052] Also, such an application of the reliability improvement method can be indicated by another signal field other than the MCS and N SS information, such as the reliability improvement flag field shown in FIG. 11.

[0053] The receiving STA that receives a PPDU having a preamble part indicating that the extended frequency diversity method is applied shall decode and demodulate the PPDU according to a predefined / notified instruction regardless of whether the reliability improvement method is applied, and obtain additional gain.

[0054] FIG. 10 shows an exemplary EHT PPDU 1000 for subcarrier modulation across multiple spatial streams according to one embodiment of the present disclosure. The EHT PPDU 1000 may include a non-High Throughput (Legacy) Short Training field (L-STF), a non-High Throughput (Legacy) Long Training field (L-LTF), a non-High Throughput (Legacy) SIGNAL (L-SIG) field, a Repeated L-SIG (RL-SIG) field, a Universal Signal (U-SIG) field, an EHT-STF, an EHT-LTF), a Data field, and a Packet Extension (PE) field. The time lengths of the L-STF, L-LTF, L-SIG field, RL-SIG field, U-SIG field, EHT-SIG field, and EHT-STF are 8 μs, 8 μs, 4 μs, 4 μs, 8 μs, 8 μs, and 8 μs, respectively, and the EHT-LTF may include two or more EHT-LTF symbols having a time length that varies according to the guard interval (GI) and the LTF size.

[0055] The EHT-SIG field includes a Common field and a User Specific field. The User Specific field includes one or more User fields, and each User field includes an STA ID field, an MCS field, an N SS field, a Beamformed field, and a Coding field. The MCS field and / or the N SS field can provide information on whether an extended frequency diversity scheme (e.g., extended DCM) and / or a reliability improvement method is applied. Table 1 shows the coding scheme of the first example indicated by the MCS field and the N SS field, and N SS is 1 or 2.

[0056]

Table 1

[0057] Table 2 shows the encoding method of the second example indicated by the MCS field and the N SS field, and N SS can be either 1, 2, or 3.

[0058]

Table 2

[0059] FIG. 11 shows an EHT PPDU1100 which is another example for subcarrier modulation over multiple spatial streams according to an embodiment of the present disclosure. The PPDU1100 is similar to the PPDU1000 shown in FIG. 10, but each User field in the User Specific field of the EHT-SIG field further includes a Reliability Improvement Flag field that functions as another signaling for indicating whether a reliability improvement method is applied, while the MCS and N SS field indicate whether an extended frequency diversity method is applied. Table 3 shows the encoding method of the second example indicated by the MCS field, the N SS field, and the Reliability Improvement Flag field, and N SS is 1 or 2. The reliability improvement flag may be reserved when the Nss field is set to 1 (the value is ignored by the receiving unit). (Indicated by " / " in Table 3.)

[0060]

Table 3

[0061] Advantageously, by using these fields to provide information regarding the application of the extended frequency diversity scheme and the reliability improvement method, the DCM can be extended to two or more spatial streams, and spatial diversity gain can be provided to the DCM and the EHT DUP mode without additional signaling bits in the preamble portion of the PPDU or signal.

[0062] FIG. 12 shows a schematic diagram of a communication device 1200 according to the present disclosure. The communication device 1200 may also be implemented as an AP or an STA.

[0063] As shown in FIG. 12, the communication device 1200 may include a circuit 1214, at least one wireless transmission unit 1202, at least one wireless reception unit 1204, and at least one antenna 1212 (for simplicity, only one antenna is depicted in FIG. 12 for illustrative purposes). The circuit 1214 includes at least one control unit 1206, which may be used for software and / or hardware-assisted execution of designed tasks, including communication control with one or more other communication devices within the MIMO wireless network. The circuit 1214 may further include at least one transmission signal generation unit 1208 and at least one reception signal processing unit 1210. The at least one control unit 1206 can control the at least one transmission signal generation unit 1208 to generate a PPDU to be transmitted to one or more other communication devices through the at least one wireless transmission unit 1202. For example, the PPDU can be a PPDU used for downlink transmission if the communication device 1200 is an AP, or a PPDU used for trigger-based uplink transmission if the communication device 1200 is a STA. The at least one control unit 1206 may control the at least one reception signal processing unit 1210 to process the MAC frames and PPDUs received from one or more other communication devices under the control of the at least one control unit 1206 through the at least one wireless reception unit 1204. For example, the PPDU can be a PPDU used for trigger-based uplink transmission if the communication device 1200 is an AP, or a PPDU used for downlink transmission if the communication device 1200 is a STA. The at least one transmission signal generation unit 1208 and the at least one reception signal processing unit 1210 can be stand-alone modules of the communication device 1200 that communicate with the at least one control unit 1206 for the above functions, as shown in FIG. 12. Alternatively, the at least one transmission signal generation unit 1208 and the at least one reception signal processing unit 1210 may be included in the at least one control unit 1206. It is obvious to those skilled in the art that the arrangement of these functional modules is flexible and may vary according to actual needs and / or requirements.Data processing, virtual memory, and other related control devices can be provided on a suitable circuit board and / or within a chipset. In various embodiments, during operation, at least one wireless transmission unit 1202, at least one wireless reception unit 1204, and at least one antenna 1212 can be controlled by at least one control unit 1206.

[0064] The communication device 1200 can provide functions necessary for modulating subcarriers across a plurality of spatial streams during operation. For example, the communication device 1200 is an AP or a transmitting STA, and the circuit 1214 (for example, at least one transmission signal generation unit 1208 of the circuit 1214) can be configured to set first information and second information. The first information may indicate whether mapping two or more modulation symbols modulated from information bits of a signal to two or more subcarriers is applicable across two or more spatial streams of an OFDM symbol. The second information may indicate whether data rate adjustment is applied to the signal. The at least one wireless transmission unit 1202 may transmit a signal using mapping of two or more modulation symbols across two or more spatial streams and / or data rate adjustment. The signal may include both the first information and the second information.

[0065] In one embodiment, the circuit 1214 (for example, at least one transmission signal generation unit 1208 of the circuit 1214) is further configured to set a signal field related to an MCS coding scheme (for example, an MCS field) and / or the number of spatial streams (N SS field) of a signal to include the first information and the second information. In another embodiment, the second information is indicated by setting another signal field (for example, a Reliability Improvement Flag field).

[0066] In various embodiments, mapping two or more modulation symbols modulated from the information bits of a signal to two or more subcarriers is applied across two or more spatial streams of an OFDM symbol and includes any of the following.

[0067] a) Map two of two or more modulation symbols modulated from the information bits of the signal to a first subcarrier of two or more subcarriers in a first spatial stream of two or more spatial streams of the OFDM symbol and a second subcarrier of two or more subcarriers in a second spatial stream, respectively.

[0068] b) Map two of two or more modulation symbols modulated from the information bits of the signal to the same two or more subcarriers in each spatial stream of two or more spatial streams.

[0069] c) Map two of two or more modulation symbols modulated from a first information bit of the signal to two or more subcarriers in a first spatial stream of two or more spatial streams of the OFDM symbol and a second spatial stream of two or more spatial streams of an adjacent OFDM symbol, and map two of two or more modulation symbols modulated from a second information bit of the signal to two or more subcarriers in the second spatial stream of two or more spatial streams of the OFDM symbol and a first spatial stream of two or more spatial streams of the adjacent OFDM symbol, and the transmitter transmits the signal through the first and second spatial streams of the OFDM symbol and the adjacent OFDM symbol.

[0070] d) Phase rotation for one of two or more modulation symbols mapped to one of two or more subcarriers in one of two or more spatial streams of the OFDM symbol.

[0071] e) Inversion of one of two or more modulation symbols mapped to one of two or more subcarriers in one of two or more spatial streams of an OFDM symbol.

[0072] f) Conjugation of one of two or more modulation symbols mapped to one of two or more subcarriers in one of two or more spatial streams of an OFDM symbol.

[0073] g) Switching of two of two or more modulation symbols mapped to two of two or more subcarriers in one of two or more spatial streams.

[0074] h) Phase rotation, inversion, or conjugation of one of two or more modulation symbols mapped to one of two or more subcarriers in one of two or more spatial streams of one or more replicas of an OFDM symbol.

[0075] i) Inversion of one of two or more modulation symbols mapped to one of two or more subcarriers in one of two or more spatial streams of one or more replicas of an OFDM symbol.

[0076] j) Conjugation of one of two or more modulation symbols mapped to one of two or more subcarriers in one of two or more spatial streams of one or more replicas of an OFDM symbol.

[0077] In various embodiments, the adjustment of the data rate includes any of the following.

[0078] a) Duplicate the OFDM symbols in the payload portion of the signal, and the transmitter transmits a signal including the OFDM symbols in the payload portion and one or more replicas of the OFDM symbol adjacent to the OFDM symbol.

[0079] b) Duplicate the OFDM symbol block in the payload part of the signal, and the transmitter transmits a signal including the OFDM symbol block in the payload part and one or more duplicates of the OFDM symbol block adjacent to the OFDM symbol block. The OFDM symbol block includes an OFDM symbol and one or more adjacent OFDM symbols.

[0080] c) Switch two of the two or more modulation symbols mapped to two of the two or more subcarriers of one or more duplicates of the OFDM symbol.

[0081] d) Generate a signal including information bits in the first frequency segment of the payload part of the signal and one or more duplicates of the information bits in one or more second frequency segments by frequency duplication of the payload part of the signal.

[0082] For example, the communication device 1200 is a receiving STA, and at least one radio receiving unit 1204 can receive a signal including first information and second information. The first information can indicate whether mapping two or more modulation symbols modulated from the information bits of the signal to two or more subcarriers is applied across two or more spatial streams of the OFDM symbol. The second information can indicate whether adjustment of the data rate is applied to the signal. The circuit 1214 (for example, the circuit 1214 such as at least one received signal processing unit 1210) can be configured to decode and demodulate the signal to obtain information on the information bits mapped to two or more spatial streams.

[0083] FIG. 13 shows a flowchart 1300 illustrating a communication method performed by a first communication device. The first communication device can be, for example, an AP or a transmitting STA according to various embodiments of the present disclosure. In step 1302, steps of setting first information (mapping information of modulation symbols) and second information (data rate adjustment information) are executed. The first information indicates whether mapping two or more modulation symbols modulated from information bits of a signal to two or more subcarriers is applied over two or more spatial streams of an OFDM symbol, and the second information may indicate whether data rate adjustment is applied to the signal. In step 1304, a step of transmitting a signal using mapping of two or more modulation symbols over two or more spatial streams and / or data rate adjustment is executed, and the signal may include the first information and the second information.

[0084] FIG. 14 shows a flowchart 1400 illustrating a communication method performed by a second communication device. The second communication device can be, for example, a receiving STA according to various embodiments of the present disclosure. In step 1402, a step of receiving a signal including first information (mapping information of modulation symbols) and second information (data rate adjustment information) is executed. The first information indicates whether mapping two or more modulation symbols modulated from information bits of a signal to two or more subcarriers is applied over two or more spatial streams of an OFDM symbol, and the second information indicates whether data rate adjustment is applied to the signal. In step 1404, a step of decoding and demodulating the signal is executed to obtain information on information bits mapped to two or more spatial streams.

[0085] In the following paragraphs, a first embodiment of the present disclosure including application of an extended frequency diversity scheme such as a spatial frequency diversity scheme (SFDS) applied to two or more spatial streams (SS) without using a reliability improvement method is described.

[0086] FIG. 15 shows a block diagram 1500 illustrating an extended frequency diversity scheme applied to two information bits across two spatial streams (SS1, SS2) of an OFDM symbol according to a first embodiment of the present disclosure. In particular, the SFDS scheme is applied, and the information bits from the first spatial stream (SS1) are mapped to two modulation symbols X 1k , X 1kDCM . One of the modulation symbols (e.g., X 1k ) is mapped to the first subcarrier (m) corresponding to the first spatial stream (SS1), and the other modulation symbol (e.g., X 1kDCM ) is mapped to the second subcarrier (n) corresponding to the second spatial stream (SS2). Another information bit from the second spatial stream is also modulated to two modulation symbols X 2k , X 2kDCM mapped to a pair of subcarriers (m, n). One of the modulation symbols (e.g., X 2k ) is mapped to the first subcarrier (m) corresponding to the second spatial stream (SS2), and the other modulation symbol (e.g., X 2kDCM ) is mapped to the second subcarrier (n) corresponding to the first spatial stream (SS1). The pair of subcarriers (m, n) are widely separated in frequency within the spatial stream (e.g., separated by N SD / 2, where N SD is the number of data subcarriers per OFDM symbol or the number of data subcarriers within a subband (e.g., 20 / 40 / 80 MHz subband)).

[0087] Preferably, a phase rotation or sign inversion is applied to the modulation symbols on the partial frequency subcarriers of the spatial stream (e.g., the second modulation symbol from another information bit mapped to the second subcarrier (n) corresponding to the first spatial stream is rotated or inverted from X 2kDCM to -X 2kDCM , and the corresponding modulation symbol from another spatial stream (e.g., the second modulation symbol from the information bit (e.g., X1kDCM ) is distinguished from that corresponding to the second spatial stream mapped to the same second sub-carrier (n).

[0088] Applying such an SFDS scheme to multiple SSs can provide a specific spatial diversity gain in a specific propagation environment. For example, in a small room environment with a flat fading channel that has a clear line of sight (LOS), multiple SSs may function better for spatial diversity. In a large room environment with no line of sight (NLOS), the spatial diversity effect is probably small because the frequency diversity effect is large enough. Even when applying SFDS by applying the same total power to multiple SSs in an AWGN channel, there may be no spatial diversity gain.

[0089] Note that it should be noted that multiple spatial stream transmissions are sent to a single user. A receiving STA that receives a PPDU having a preamble indicating that SFDS is applied to multiple spatial streams combines demodulated symbols from different SSs according to the SFDS mapping to obtain a signal and a spatial diversity gain before decoding the PPDU.

[0090] FIG. 16 shows a transmission block diagram 1600 showing the processing of a data field through an extended frequency diversity scheme according to the first embodiment of the present disclosure. The processing of the transmitting unit is the same as that shown in FIG. 5, and includes a pre-FEC PHY padding unit, a scrambler unit, an LDPC encoder unit, a post-FEC PHY padding unit, and a stream parser unit (N SS=1), using a constellation mapper unit and an LDPC tone mapper unit to process a single spatial stream. Specifically, in this first embodiment, the constellation mapper unit maps each block of encoded bits to modulation symbols using BPSK, DCM, and SFDS schemes, maps each modulation symbol to two OFDM subcarriers, and then transmits the symbols to the LDPC tone mapper unit and the spatial mapper unit to map the spatial stream to two or more transmit chains (each transmit chain is indicated by an arrow pointed from the spatial mapper unit).

[0091] In the following paragraphs, a second embodiment of the present disclosure is described, including the application of an extended frequency diversity scheme such as dual carrier modulation (DCM) applied to multiple spatial streams (SS) without a reliability improvement method. In contrast to the conventional DCM scheme, in the DCM of this embodiment, the same information bits and modulation symbols are replicated (i.e., spatially replicated) to multiple SSs with cyclic shift diversity (CSD) applied.

[0092] According to the second embodiment, when the application of the extended frequency diversity scheme is shown, two different options / examples of spatial replication are applicable. (1) Normal spatial replication without CSD applied, and (2) Spatial replication with CSD applied such as partial phase rotation or code inversion.

[0093] FIG. 17 shows a block diagram 1700 showing that an extended frequency diversity scheme with spatial replication under Option 1 according to the second embodiment of the present disclosure is applied to the information bits across all spatial streams of an OFDM symbol. FIG. 18 shows a block diagram 1800 showing that an extended frequency diversity scheme with spatial replication under Option 2 according to the second embodiment of the present disclosure is applied to the information bits across all spatial streams of an OFDM symbol.

[0094] Referring to FIG. 17, in the extended frequency diversity scheme under Option 1 in the second embodiment, the DCM scheme with normal spatial replication is applied to a plurality of spatial streams. In particular, the information bits are two modulation symbols X 1k , X 1kDCM which are modulated and mapped to a pair of subcarriers (m,n) corresponding to the first spatial stream (SS1). The same modulation symbols X 1k , X 1kDCM and their mapping to the subcarriers (m,n) are also replicated to the second spatial stream (SS2). The pair of subcarriers (m,n) are widely separated in frequency within the spatial stream (e.g., separated by N SD / 2, where N SD is the number of data subcarriers per OFDM symbol or the number of data subcarriers within a sub-band (e.g., 20 / 40 / 80 MHz sub-band)).

[0095] Referring to FIG. 18, in the extended frequency diversity scheme under Option 2 in the second embodiment, the DCM scheme with spatial replication and CSD is applied to a plurality of spatial streams. In particular, the information bits are modulated to two modulation symbols X 1k , X 1kDCM which are mapped to a pair of subcarriers (m,n) corresponding to the first spatial stream (SS1). The same modulation symbols X 1k , X 1kDCM and their subcarrier (m,n) mapping are also replicated to the second spatial stream (SS2). In contrast to Option 1, a phase rotation or sign inversion is applied to the modulation symbols on the partial frequency subcarriers from the spatial stream (e.g., the second modulation symbol mapped to the second subcarrier (n) corresponding to the second spatial stream is rotated or inverted from X 1kDCM to -X 1kDCM and is distinguished from the same modulation symbol of other spatial streams (e.g., the modulation symbol X 1kDCM)。In this way, a low peak-to-average power ratio (PAPR) and high robustness can be obtained.

[0096] Under this scheme, a receiving STA that receives a PPDU having a preamble indicating that spatial replication is performed with or without rotation (Option 1 or 2) to apply DCM across multiple spatial streams combines demodulated symbols from different SSs according to the mapping before decoding the PPDU, obtaining improved spatial diversity and robustness.

[0097] Advantageously, such a DCM scheme with spatial replication applied to multiple SSs can provide the gain of spatial diversity while having the same data rate and performance as the DCM of a single SS or the transmission of a single SS with two transmit antennas.

[0098] FIG. 19 shows a transmission block diagram 1900 illustrating the processing of a data field through extended frequency diversity according to a second embodiment of the present disclosure. The processing of the transmitting unit is similar to that shown in FIG. 5 which processes a single spatial stream using an FEC pre-PHY padding unit, a scrambler unit, an LDPC encoder unit, post-FEC PHY padding, a stream parser unit (N SS = 1), a constellation mapper unit, and an LDPC tone mapper unit. Specifically, in this second embodiment, after the LDPC tone mapper unit, the spatial stream is sent to a spatial replication unit where the modulated symbols on the spatial stream are replicated into two spatial streams (each indicated by an arrow pointing out from the spatial replication unit). Next, the spatial stream and the replicated spatial streams are sent to a spatial mapper unit for mapping to two or more transmit chains. Optionally, under Option 2, one of the multiple spatial streams from the spatial replication unit is sent to a CSD unit, and after performing phase rotation or sign inversion on its modulated symbols, the spatial stream is sent to a spatial mapper unit for mapping to three transmit chains.

[0099] In the following paragraphs, a third embodiment of the present disclosure will be described in which an extended frequency diversity scheme such as dual carrier modulation (DCM) is applied to a plurality of spatial streams (SS) without a reliability improvement method. In contrast to the conventional DCM scheme, in the DCM of this embodiment, the same information bits are modulated into two or more modulation symbols using different modulation mappings (e.g., two DCM schemes), and the modulation symbols are rearranged between different SS. The rearrangement is performed on the frequency subcarriers of the OFDM symbol.

[0100] According to the third embodiment, when the application of the extended frequency diversity scheme is shown, two different options / examples of rearrangement of the frequency subcarriers are applicable. (1) The rearrangement is performed between subcarrier blocks of the symbol. (2) The rearrangement is performed between two or more adjacent subcarriers of the symbol.

[0101] FIG. 20 shows a block diagram 2000 showing an extended frequency scheme and rearrangement under Option 1 applied to the information bits across all spatial streams of an OFDM symbol according to the third embodiment of the present disclosure. FIG. 21 shows a block diagram 2100 showing an extended frequency diversity scheme and rearrangement under Option 2 applied to the information bits across all spatial streams of an OFDM symbol according to the third embodiment of the present disclosure.

[0102] In the extended frequency diversity scheme in the third embodiment, the information bit X1 is modulated using two different modulation mappings, and each modulation mapping generates a pair of modulation symbols on a spatial stream (e.g., the first spatial stream SS1). In particular, the first modulation mapping generates modulation symbols X 1k-1 and X 1kDCM-1 mapped to subcarriers m1 and n1, respectively, corresponding to the first spatial stream SS1, and the second modulation mapping generates modulation symbols X 1k-2 and X1kDCM-2 is generated. Thereafter, the modulated symbols are rearranged and mapped to another SS (e.g., SS2).

[0103] Referring to FIG. 20, under Option 1, for all four sub - carrier blocks of symbols X 1k-1 , X 1kDCM-1 , X 1k-2 and X 1kDCM-2 , rearrangements are performed at m1, m2, n1, and n2 respectively. In particular, the mapping sequence of the sub - carrier blocks of symbols in the first spatial stream (SS1) is rearranged and inverted in the second spatial stream (SS2). The first symbol (X 1k-1 ) mapped to the first sub - carrier index m1 of SS1 is rearranged to the fourth sub - carrier index n2 of SS2. The second symbol (X 1kDCM-1 ) mapped to the second sub - carrier index m2 of SS1 is rearranged to the third sub - carrier index n1 of SS2. The third symbol (X 1k-2 ) mapped to the third sub - carrier index n1 of SS1 is rearranged to the second sub - carrier index m2 of SS2. The fourth symbol (X 1kDCM-2 ) mapped to the fourth sub - carrier index n2 of SS1 is rearranged to the first sub - carrier index m1 of SS2.

[0104] Referring to FIG. 21, under Option 2, rearrangements are performed between two adjacent sub - carriers of the symbols. In particular, two adjacent sub - carriers of the symbols are grouped (e.g., X 1k-1 and X 1kDCM-1 ; X 1k-2 and X 1kDCM-2 ), and the mapping sequence of two adjacent sub - carriers of the symbols in the first spatial stream (SS1) is rearranged and inverted in the second spatial stream (SS2). The first symbol (X 1k-1) is rearranged to the second sub - carrier index m + 1 of SS2. The second symbol (X mapped to the second sub - carrier index n of SS1 1kDCM-1 ) is rearranged to the first sub - carrier index n + 1 of SS2. The third symbol (X mapped to the third sub - carrier index m + 1 of SS1 1k-2 ) is rearranged to the fourth sub - carrier index m of SS2. The fourth symbol (X mapped to the fourth sub - carrier index n + 1 of SS1 1kDCM-2 ) is rearranged to the third sub - carrier index n of SS2.

[0105] Such rearrangement between spatial streams is applied in addition to any extended frequency diversity scheme described in various embodiments of the present disclosure, and further robustness and frequency diversity can be obtained according to the embodiments. For example, as shown in FIG. 20, phase rotation or sign inversion can be applied to the modulated symbols on the partial - frequency sub - carriers from the spatial streams (e.g., the second modulated symbol mapped to the third sub - carrier (n1) corresponding to the second spatial stream is rotated or inverted from X 1k-2 to - X 1k-2 and is distinguished from the corresponding modulated symbols of other spatial streams).

[0106] Note that multiple - spatial - stream transmission is sent to a single user. Under this scheme, a receiving - side STA that receives a PPDU having a preamble indicating that stream - to - stream rearrangement is applied to multiple spatial streams with / without partial rotation according to Option 1 or 2 of this third embodiment combines the demodulated symbols from different SSs according to the mapping before decoding the PPDU to obtain improved spatial diversity and robustness.

[0107] Advantageously, such a DCM scheme with spatial replication applied to multiple SSs can provide the gain of spatial diversity and an additional gain of frequency diversity at the same data rate as DCM using a single SS, and also provides better robustness because one information bit can be carried by 2N subcarriers in N SSs.

[0108] FIG. 22 shows a transmission block diagram 2200 illustrating the processing of a data field through an extended frequency diversity scheme according to a third embodiment of the present disclosure. The processing of the transmitter is similar to that for processing a single spatial stream shown in FIG. 5 using an FEC pre-PHY padding unit, a scrambler unit, an LDPC encoder unit, an FEC post-PHY padding unit, a stream parser unit (N SS = 1), a constellation mapper unit, and an LDPC tone mapper unit. Specifically, in this third embodiment, after the constellation mapper unit maps each block of bits encoded using the BPSK, DCM scheme to modulation symbols, the modulation symbols are sent to a permutation unit that performs a permutation of the frequency subcarriers within the spatial stream and maps each modulation symbol to two OFDM subcarriers. Thereafter, the symbols mapped to the spatial stream are sent to an LDPC tone mapper unit and a spatial mapper unit that map the spatial stream to two or more transmit chains.

[0109] In the following paragraphs, a fourth embodiment of the present disclosure is described in which an extended frequency diversity scheme such as dual carrier modulation (DCM) is applied to a space-time stream (STS) generated by a space-time block coding (STBC) scheme from one or more SSs without using a reliability improvement method.

[0110] STBC is a robust transmission technique for OFDM symbols, where the same information bits from the SS are further mapped to two or more STSs. In other words, n SSs are mapped to 2n STSs. The STBC operation should be performed between the constellation mapper and the space mapper. In particular, the STBC process operates on the complex modulation symbols of consecutive pairs of OFDM symbols.

[0111] FIG. 23 shows a block diagram 2300 illustrating an extended frequency diversity scheme applied to two information bits from two spatial streams of OFDM symbols to generate STSs using STBC according to a fourth embodiment of the present disclosure.

[0112] The information bit X1 from the spatial stream (e.g., the first spatial stream SS1) is modulated to a pair of modulation symbols X 1k and X 1kDCM on OFDM symbol 2n using the DCM scheme. On the other hand, the second information bit X2 from the spatial stream SS1 is also modulated to a pair of modulation symbols X 2k and X 2kDCM on the adjacent OFDM symbol 2n + 1 using the DCM scheme.

[0113] In the extended frequency diversity scheme of the fourth embodiment, the modulation symbols from the SS (SS1) are processed through the STBC unit and mapped to two STSs (STS1 and STS2), with each STS containing the same modulation symbols. As shown in FIG. 23, the two STSs can be from different OFDM symbols. In particular, the modulation symbols X 1k , X 1kDCM from SS1 of OFDM symbol 2n are mapped to X 1k , X 1kDCM of STS1 of OFDM symbol 2n and -X * 1k , -X * 1kDCM of STS2 of the adjacent OFDM symbol 2n + 1. On the other hand, the modulation symbols X 2k, X 2kDCM is the X of STS1 of OFDM symbol 2n + 1 2k , X 2kDCM and -X of STS2 of the adjacent OFDM symbol 2n * 2k , X * 2kDCM is mapped to. In this example, the modulation symbols from the OFDM symbols mapped to the STS of adjacent symbols (e.g., X * 1k , X * 2k ) have a phase rotation or sign inversion applied to them and are distinguished from the corresponding modulation symbols from another STS.

[0114] Advantageously, such DCM schemes and STBC schemes applied to multiple SSs can generate two STSs from each SS and provide spatial diversity gain and better robustness at the same data rate as DCM in a single SS.

[0115] Alternatively, unlike the above DCM scheme by one SS, the STBC scheme can be applied to DCM by multiple SSs. In such a case, there are three or more STSs and more antennas and EHT - LTF symbols are required for transmission.

[0116] Such a DCM scheme between STSs generated by the STBC scheme is applied in addition to any extended frequency diversity scheme described in various embodiments of the present disclosure, and further robustness and frequency diversity can be obtained according to the embodiments. For example, as shown in FIG. 23, a phase rotation or sign inversion is applied to the modulation symbols from the OFDM symbols mapped to the STS of adjacent symbols (e.g., X * 1k , X * 2k ).

[0117] FIG. 24 shows a transmission block diagram 2400 illustrating the processing of a data field through an extended frequency diversity scheme according to a fourth embodiment of the present disclosure. The processing of the transmission unit is the same as that shown in FIG. 5, and includes a pre-FEC PHY padding unit, a scrambler unit, an LDPC encoder unit, a post-FEC PHY padding unit, a stream parser unit (N SS = 1), a constellation mapper unit, and an LDPC tone mapper unit to process a single spatial stream. Specifically, in this fourth embodiment, after the LDPC tone mapper unit, the spatial stream is sent to the STBC unit, which generates two spatio-temporal streams (each indicated by an arrow pointed from the STBC unit), and these two spatio-temporal streams are sent to the spatial mapper unit for mapping to two or more transmission chains.

[0118] In the following paragraphs, a fifth embodiment of the present disclosure is described in which an extended frequency diversity scheme such as quad sub-carrier modulation (QCM) is applied to multiple SSs without a reliability improvement method.

[0119] FIG. 25 shows a block diagram 2500 illustrating an extended frequency diversity scheme applied to two information bits through two spatial streams (SS1, SS2) of an OFDM symbol according to a fifth embodiment of the present disclosure.

[0120] In the extended frequency diversity scheme in the fifth embodiment, the QCM scheme is applied to multiple SSs. In particular, the information bits from the first spatial stream (SS1) are modulated into four modulation symbols X 1k 、X 1kDCM 、-X 1kDCM 、X 1kDCM mapped to four sub-carriers (m, n1, n2, n3). Another information bit from the second spatial stream (SS2) is also modulated into four modulation symbols X 2k 、X 2kDCM, -X 2kDCM , X 2kDCM is modulated to. Subcarriers (m, n1, n2, n3) are widely separated in frequency within a spatial stream (e.g., N SD / 4 separated, where N SD is the number of data subcarriers per OFDM symbol or the number of data subcarriers within a sub-band (e.g., 20 / 40 / 80 MHz sub-band)).

[0121] Advantageously, such a QCM scheme applied to multiple SSs can provide spatial and frequency diversity at the same data rate as DCM in a single SS. However, since the RU tone size cannot be divided into four equal units, it does not need to be applied to a 26-tone resource unit (RU). Under such a scheme, different spatial streams may be transmitted to different users. Such a QCM scheme can also be integrated with any extended frequency diversity scheme described in various embodiments of the present disclosure, and further robustness and frequency diversity can be obtained according to the embodiments.

[0122] FIG. 26 shows a transmission block diagram 2600 illustrating the processing of a data field through an extended frequency diversity scheme according to a fifth embodiment of the present disclosure. The processing of the transmitter is similar to that shown in FIG. 5 and uses an FEC pre-PHY padding unit, a scrambler unit, an LDPC encoder unit, an FEC post-PHY padding unit, a stream parser unit (N SS = 1), a constellation mapper unit, and an LDPC tone mapper unit to process a single spatial stream. Specifically, in this fifth embodiment, the constellation mapper unit maps each block of bits encoded using BPSK and the QCM scheme to four modulation symbols, and before the spatial stream is sent to the LDPC tone mapper unit and the spatial mapper unit to map the spatial stream to three transmit chains, each modulation symbol is mapped to four OFDM subcarriers.

[0123] In the following paragraphs, a sixth embodiment of the present disclosure is described, in which the application of the extended frequency diversity method with a reliability improvement method, for example, the application of the extended frequency diversity method in the first to fifth embodiments described above, is explained.

[0124] In particular, in this embodiment, a time-domain based iterative reliability improvement method is described, and the following three different options / examples of time-domain based iteration are applied. (1) Direct time repetition in which each OFDM symbol in the payload part of the PPDU is replicated one or more times before the next OFDM symbol. (2) Repetition of OFDM symbols with sub-carrier permutation in which each OFDM symbol in the payload part of the PPDU is replicated one or more times before the next OFDM symbol and the sub-carriers of the replicated symbols are permuted. (3) Repetition of OFDM symbols by sub-carriers-time block coding (CTBC) in which two or more OFDM symbols are grouped into OFDM symbol blocks and each OFDM symbol block in the payload part of the PPDU is replicated one or more times before the next OFDM symbol block.

[0125] FIG. 27 shows an exemplary payload part 2700 of a PPDU to which the time-domain based iterative reliability improvement method is applied under Option 1 according to the sixth embodiment of the present disclosure. FIG. 28 shows an exemplary payload part 2800 of a PPDU to which the time-domain based iterative reliability improvement method is applied under Option 2 according to the sixth embodiment of the present disclosure. In FIGS. 27 and 28, the number of repetitions 2 (N = 2) is shown.

[0126] The payload portions 2700, 2800 of the PPDU may include a plurality of OFDM symbols (OFDM SYM1, 2, ..., N). When a time-domain based repeated reliability improvement method is applied under Option 1, each OFDM symbol (OFDM SYM1, 2, ..., N) within the payload portion 2700 is replicated once (N = 2), and there are two identical OFDM SYMs existing immediately before the next OFDM SYM along the payload portion. The replicated OFDM symbols (OFDM SYM R1, 2, ..., N) are assigned immediately after the original OFDM symbol before the next OFDM symbol. As a result, the data rate is decreased and adjusted to 1 / N, and the transmission reliability is improved. However, since the channel states of adjacent OFDM symbols are very similar, only a power gain is obtained.

[0127] When a time-domain based repeated reliability improvement method is applied under Option 2, in addition to the replication of the OFDM symbols (OFDM SYM1, 2, ..., N) within the payload portion described in Option 1, the subcarriers of the replicated OFDM symbols (OFDM SYM X R, where X = 1, 2, ..., N) are rearranged. As a result, the data rate is decreased and adjusted to 1 / N, and not only the transmission reliability is improved, but also power and diversity gains are provided compared to Option 1.

[0128] FIG. 29 shows a block diagram 2900 showing a reliability improvement method applied under Option 2 to an OFDM symbol (e.g., OFDM SYM N) within the payload portion of the PPDU according to the sixth embodiment of the present disclosure. Information bits are two modulation symbols X 1k , X 1kDCMIt is modulated to. When the reliability improvement method is applied under Option 2 according to the sixth embodiment, repetitions of the OFDM SYM N R are generated. In the repetition of the OFDM symbol (OFDM SYM N R), the first modulated symbol of the repetition is mapped to the second subcarrier (n), the second modulated symbol of the repetition is mapped to the first subcarrier (m), and is distinguished from the corresponding modulated symbol of the original OFDM symbol (OFDM SYM N).

[0129] Figure 30 shows an exemplary payload portion 3000 of a PPDU to which a time-domain based repetition reliability improvement method is applied under Option 3 according to the sixth embodiment of the present disclosure. In this example, each adjacent pair of OFDM symbols for CTBC processing is grouped into OFDM blocks, and the number of repetitions of the OFDM symbol (block) is 2 (N = 2). Accordingly, each pair of OFDM symbols (OFDM blocks) is mapped to four (or two pairs) of OFDM symbols.

[0130] In particular, the payload portion of the PPDU may include a plurality of OFDM symbols (OFDM SYM 1, 2,..., N, N + 1), and two adjacent OFDM symbols along the payload portion are grouped into OFDM symbol blocks. When the time-domain based repetition reliability improvement method is applied under Option 3, each OFDM symbol block (e.g., OFDM SYM 1 and OFDM SYM 2 and OFDM SYM N and OFDM SYM N + 1) within the payload portion is replicated once (N = 2), so that there are two identical OFDM symbol blocks in front of the next OFDM SYM block along the payload portion. The replicated OFDM symbol blocks (OFDM SYM 1 R and OFDM SYM 2 R and OFDM SYM N R and OFDM SYM N + 1 R) are assigned immediately after the original OFDM symbol block in front of the next OFDM symbol block. This not only reduces and adjusts the data rate to 1 / N and improves the reliability of transmission, but also improves the power gain and robustness compared to Option 1.

[0131] CTBC is similar to STBC. Instead of mapping each SS to two spatial streams as in the case of STBC, in the case of CTBC, each pair of OFDM symbols (assuming an OFDM block consisting of two OFDM symbols) is mapped to 2N OFDM symbols. Here, N is the number of repetitions. CTBC processing acts on the complex modulation symbols of consecutive pairs of OFDM symbols. The same information bits from the OFDM symbols are mapped to two or more OFDM symbols. Furthermore, permutation within the OFDM symbol can also be performed to add frequency diversity.

[0132] This reduces and adjusts the data rate to 1 / N, and improves the transmission reliability. However, since the channel states of adjacent OFDM symbols are very similar, only power gain is obtained.

[0133] When the time-domain based reliability improvement method under Option 2 is applied, in addition to the replication of the OFDM symbols (OFDM SYM 1, 2,..., N) within the payload part described in Option 1, the subcarriers of the replicated OFDM symbols (OFDM SYM R 1, 2,..., N) are permuted. This not only reduces and adjusts the data rate to 1 / N and improves the transmission reliability, but also provides power and diversity gains compared to Option 1.

[0134] FIG. 31 shows a block diagram 3100 illustrating the reliability improvement method applied under Option 3 to two information bits from the spatial streams of two OFDM symbols to generate four OFDM symbols using CTBC according to the sixth embodiment of the present disclosure.

[0135] The information bit X1 from the spatial stream (e.g., the first spatial stream SS1) is modulated using the DCM method and mapped to a pair of modulation symbols X 1k and X 1kDCMOn the other hand, adjacent information bits X2 from the spatial stream SS1 are also modulated using the DCM method and mapped to a pair of modulation symbols X 2k and X 2kDCM resulting in...

[0136] The modulation symbols from SS1 of the OFDM symbol block (including symbols 2n and 2n + 1) are processed via the CTBC unit and replicated to generate two replicated OFDM SYM 2n+2 and 2n+3 with the same modulation symbols mapped to the subcarriers (m1, m2). In this example shown in Fig. 31, a rearrangement within the replicated OFDM symbols is applied, which switches the subcarrier mapping of the OFDM symbols. As a result, the second modulation symbol mapped to the second subcarrier of the original OFDM symbol is mapped to the first subcarrier of the replicated OFDM symbol, and the first modulation symbol mapped to the first subcarrier of the original OFDM symbol is mapped to the second subcarrier of the replicated OFDM symbol.

[0137] Furthermore, a rearrangement within the replicated OFDM symbol block (OFDM symbols 2n+2 and 2n+3) is applied, which switches the order of the OFDM symbols within the replicated OFDM symbol block. In particular, in the replicated OFDM symbol block, when including the first OFDM symbol 2n+2 and the second OFDM symbol 2n+3, the first OFDM symbol 2n+2 includes the modulation symbols X 2k and X 2kDCM replicated from the second OFDM symbol 2n+1 of the original OFDM symbol block, and the second OFDM symbol 2n+3 includes the modulation symbols X * 1k and -X * 1kDCM replicated from the first OFDM symbol 2n of the original OFDM symbol block. Furthermore, the modulation symbols of the replicated OFDM symbols (e.g., X of the replicated OFDM symbols 2n+3 and 2n+2) *1k , X * 2k ) is subject to phase rotation or sign inversion and is distinguished from the corresponding modulated symbols of other OFDM symbols.

[0138] Such a time-domain-based repetition method of DCM is applied in addition to any extended frequency diversity method described in various embodiments of the present disclosure, and further robustness and frequency diversity can be obtained according to the embodiments.

[0139] A receiving STA that receives a PPDU including a preamble indicating that an OFDM symbol is repeated combines symbols from different OFDM symbol blocks according to a mapping to obtain a power gain and a robustness gain before decoding and demodulating the PPDU.

[0140] FIG. 32 shows a transmission block diagram 3200 illustrating the processing of a data field through an extended frequency diversity method using a reliability improvement method according to the sixth embodiment of the present disclosure. The processing of the transmitting unit is similar to that shown in FIG. 5 that processes a single spatial stream using an FEC pre-PHY padding unit, a scrambler unit, an LDPC encoder unit, an FEC post-PHY padding unit, a stream parser unit (N SS = 1), a constellation mapper unit, and an LDPC tone mapper unit. Next, the spatial stream is sent to a spatial mapper unit that maps the spatial stream to three transmit chains. Each transmit chain is also sent to a permutation unit for duplicating the OFDM symbol and permuting (if necessary) the duplicated OFDM symbols before the transmit chain is sent to an IDFT unit to convert the OFDM subcarriers on the transmit chain into time-domain data for transmission.

[0141] In the following paragraphs, a seventh embodiment of the present disclosure is described in which an extended frequency diversity scheme (e.g., the extended frequency diversity scheme described in the first to fifth embodiments above) is applied together with another reliability improvement method (i.e., frequency replication of the payload portion of the signal).

[0142] In particular, in the reliability improvement method in the seventh embodiment, when MCS15 or MCS14 is notified respectively, frequency replication based on 1 / 2 or 1 / 4 of the payload portion of the PPDU is applied.

[0143] FIG. 33 shows an example of a 160 MHz PPDU 3300 to which 1 / 2 - based frequency replication according to the seventh embodiment of the present disclosure is applied. The 160 MHz PPDU 3300 includes a preamble portion, an EHT - STF, an EHT - LTF, and a payload portion 3302. In particular, in 1 / 2 - based frequency replication, the 160 MHz frequency segment is divided into two halves, a first half of 80 MHz frequency segment and a second half of 80 MHz frequency segment. The information bits X of the payload portion 3302 of the 160 MHz PPDU 3300 are demodulated into two modulation symbols X and X mapped to two 40 MHz frequency segments within the first 80 MHz frequency segment of the 160 MHz frequency segment. DCM and the two modulation symbols X and X DCM are replicated and mapped to the other two 40 MHz frequency segments within the second 80 MHz frequency segment of the 160 MHz frequency segment. This is similar to the EHT DUP transmission to which 1 / 2 - based replication is applied when MCS15 is notified. Note that when the RU tone size is less than 52 tones, 1 / 2 - based frequency replication is not applied.

[0144] FIG. 34 shows an example of a 160 MHz PPDU 3400 to which 1 / 4 - base frequency replication according to the seventh embodiment of the present disclosure is applied. The 160 MHz PPDU 3400 includes a preamble portion, an EHT - STF, an EHT - LTF, and a payload portion 3402. In particular, in 1 / 4 - base frequency replication, a 160 MHz frequency segment is divided into four quarters: a first quarter of a 40 MHz frequency segment, a second quarter of a 40 MHz frequency segment, a third quarter of a 40 MHz frequency segment, and a fourth quarter of a 40 MHz frequency segment. Information bits X of the payload portion 3402 of the 160 MHz PPDU 3400 are mapped to two modulation symbols X and X in two 20 MHz frequency segments within the first quarter of the 40 MHz frequency segment of the 160 MHz frequency segment. DCM are demodulated to these two modulation symbols X and X DCM which are replicated and mapped to two 20 MHz frequency segments respectively within the remaining second, third, and fourth quarters of the 40 MHz frequency segment of the 160 MHz frequency segment. Further, as shown by the replicated modulation symbols 3404 in the third quarter of the 40 MHz frequency segment, phase rotation or sign inversion may be applied to one or both of the replicated modulation symbols.

[0145] Under such a reliability improvement method, there is an advantage that adjustment to a 1 / 2 data rate is achieved and further frequency diversity is obtained. Such a reliability improvement method is applied in accordance with the seventh embodiment, together with any of the various reliability improvement methods described in the sixth and eighth embodiments of the present disclosure, to further reduce the data rate and improve the reliability.

[0146] FIG. 35 shows a transmission block diagram 3500 illustrating the processing of data fields through the extended frequency diversity scheme according to the seventh embodiment of the present disclosure. The processing of the transmitting unit is the same as that shown in FIG. 5, and includes a pre-FEC PHY padding unit, a scrambler unit, an LDPC encoder unit, a post-FEC PHY padding unit, a stream parser unit (N SS =1), a constellation mapper unit, and an LDPC tone mapper unit to process a single spatial stream. Specifically, in this seventh embodiment, after the LDPC tone mapper unit, the spatial stream is sent to a Frequency Domain Duplication unit to generate a replica of the modulated data of other frequency segments before the spatial stream is sent to a spatial mapper unit and mapped to three transmit chains.

[0147] In the following paragraphs, the eighth embodiment of the present disclosure is described, in which an extended frequency diversity scheme (e.g., the extended frequency diversity scheme described in the first to fifth embodiments above) is applied together with further reliability improvement methods through information block generation or code block concatenation schemes.

[0148] In 802.11, LDPC is an encoding scheme for the payload portion of the PPDU, and the LDPC encoder supports code block lengths of 648, 1296, and 1944. The LDPC encoder encodes an information block c = (i0, i1,..., i k-1 ) of size k by adding n - k parity bits such that H × C T = 0 (H is a (n - k) × n parity check matrix) to obtain a codeword c of size n (c = (i0, i1,..., i k-1 , p0, p1,..., p n-k-1 ).

[0149] There are two different options / examples for defining an LDPC method for encoding an information block according to the eighth embodiment. (1) By increasing the parity bits, define the LDPC method at a rate of 1 / N (N is an integer greater than 2). (2) By changing the size of the information block, define the LDPC method at a rate of K / N (K is the number of information bits, an integer greater than 0, and N is the data rate adjustment coefficient, an integer greater than 2).

[0150] Table 4 shows the LDPC information block lengths encoded under Option 1 according to the eighth embodiment, from various codeword block lengths supported by the LDPC encoder when the coding rate is 1 / 4. To support LDPC at a rate of 1 / N, the corresponding prototype matrices P1, P2, P3 are defined for parity check matrices of size 1944 / N × (1944(N - 1)) / N, 1296 / N × (1296(N - 1)) / N, 648 / N × (648(N - 1)) / N.

[0151] [Table 4]

[0152] FIG. 36 shows the codeword 3600 of the first example in the payload portion of the PPDU generated under Option 2 according to the eighth embodiment of the present disclosure. FIG. 37 shows the exemplary codeword 3700 of the second example in the payload portion of the PPDU generated under Option 2 according to the eighth embodiment of the present disclosure. FIG. 38 shows the exemplary codeword 3800 of the third example in the payload portion of the PPDU generated under Option 2 according to the eighth embodiment of the present disclosure.

[0153] Referring to FIG. 36, padding bits (N / 2 - K bits) of "0" are added to the information bits (K bits) to form an information block of N / 2 bits. The parity bits of the same N / 2 bits are generated at a rate of 1 / 2 from the information block to form a codeword. After the parity bits are generated, the transmitting unit may transmit either only the information bits with the parity bits or the repeated information bits with the parity bits. In this example, since the length of the codeword is the same as the current specification, a similar LDPC tone mapping can be used.

[0154] Alternatively, as shown in FIG. 37, no padding bits are added to the information bits (K bits), the information block includes only the information bits, and N - bit parity bits are added to form a codeword. In this example, since the length of the codeword may be different from the current specification, different LDPC tone mapping methods may be used.

[0155] Alternatively, as shown in FIG. 38, instead of adding (N / 2 - K) - bit padding bits, the information bits are repeated by (N / 2 - K) bits within the codeword. The parity bits of the same N / 2 bits are generated at a rate of 1 / 2 from the information block to form a codeword. In this example, since the length of the codeword is the same as the current specification, a similar LDPC tone mapping can be used.

[0156] Additionally or alternatively, in addition to defining an LDPC method for encoding the information block, the reliability improvement method according to the eighth embodiment can also be achieved by concatenating N code blocks generated from the same information block. The code blocks are generated by adding parity bits to the information block, but different code blocks are generated by encoding the same information block using different parity check matrices, and the transmission reliability can be improved by concatenating these different code blocks.

[0157] FIG. 39 shows an exemplary codeword 3900 including two concatenated code blocks generated from an information block according to the eighth embodiment of the present disclosure. The information block c includes information bits, and the LDPC encoder encodes the information block into two code blocks at a rate of 1 / 2 using different parity bits (p1k and p2k). The coding rate within each code block is 1 / 2, but the overall coding rate for the payload portion is 1 / 2N. To support LDPC concatenated at a rate, corresponding prototype matrices P1, P2, P3 different from the current prototype matrix are defined at a coding rate of 1 / 2 for codeword block lengths 648, 1296, 1944 of different parity check matrices.

[0158] By the reliability improvement method through the information block generation or code block concatenation method according to the eighth embodiment, a lower data rate can be achieved compared to 802.11be, and new prototypes and coding mechanisms are required.

[0159] FIG. 40 shows a transmission block diagram 4000 showing the processing of a data field through the extended frequency diversity method according to the eighth embodiment of the present disclosure. The processing of the transmission unit is the same as that shown in FIG. 5, and a single spatial stream is processed using an FEC pre-PHY padding unit, a scrambler unit, an LDPC encoder unit, an FEC post-PHY padding unit, a stream parser unit (N SS = 1), a constellation mapper unit, and an LDPC tone mapper unit. Specifically, in this eighth embodiment, the LDPC encoder unit is a special LDPC encoder unit, and before transmitting the encoded bits to the FEC post-PHY padding unit, parity bits and repeated information bits can be added to encode the information block.

[0160] As described above, the embodiments of the present disclosure provide an advanced communication system, communication method, and communication device for subcarrier modulation across multiple spatial streams in a MIMO WLAN network.

[0161] The present disclosure can be implemented by software, by hardware, or by software cooperating with hardware. Each functional block used in the description of the above embodiments is realized, partially or wholly, as an LSI which is an integrated circuit, and each process described in the above embodiments may be controlled, partially or wholly, by one LSI or a combination of LSIs. The LSI can be formed individually as a chip, or one chip can be formed so as to include part or all of the functional blocks. The LSI can include a data input / output section coupled to itself. Depending on the degree of integration, the LSI may also be referred to as an IC (Integrated Circuit), a system-on-chip (SoC), a system LSI, a super LSI, an ultra LSI. However, the technology for implementing the integrated circuit is not limited to LSI, and can be implemented by using a dedicated circuit, a general-purpose processor, or a dedicated processor. Furthermore, an FPGA (Field Programmable Gate Array) that can be programmed after the manufacture of the LSI, or a reconfigurable processor that can reconfigure the connection and setting of circuit cells arranged inside the LSI can also be used. The present disclosure can be implemented as digital processing or analog processing. As a result of the progress of semiconductor technology or another derivative technology, if the LSI is replaced by a future integrated circuit technology, the functional blocks can be integrated using the future integrated circuit technology. Biotechnology can also be applied.

[0162] The present disclosure can be implemented by any type of apparatus, device, or system having a communication function (referred to as a communication apparatus).

[0163] Non-limiting examples of communication devices include telephones (such as mobile phones, smartphones, etc.), tablets, personal computers (PCs) (such as laptops, desktops, notebooks, etc.), cameras (such as digital still cameras / video cameras, etc.), digital players (such as digital audio players / video players, etc.), wearable devices (such as wearable cameras, smartwatches, tracking devices, etc.), game consoles, digital book readers, telehealth / telemedicine (remote healthcare / medical prescription) devices, vehicles with communication functions (such as automobiles, airplanes, ships, etc.), and combinations of the various devices described above.

[0164] The communication device is not limited to being portable or movable, and includes any type of device, apparatus, system that is not portable or is fixed, for example, smart home devices (such as household appliances, lighting devices, smart meters or measuring devices, control panels, etc.), vending machines, and any other "Things" that may exist on the IoT (Internet of Things) network.

[0165] Communication may include, for example, the step of exchanging data through a cellular system, a wireless LAN system, a satellite system, etc., and various combinations thereof.

[0166] The communication device may include devices such as a control unit and sensors connected to a communication device that executes the communication function described in the present disclosure. For example, the communication device may include a control unit and sensors that generate control signals and data signals used by the communication device that executes the communication function of the communication device.

[0167] In addition, the communication device may include infrastructure facilities such as base stations, access points, and other devices, apparatuses, systems that communicate or control with devices such as those in the above non-limiting examples.

[0168] Although some features of various embodiments have been described with reference to the apparatus, it is understood that the corresponding features also apply to the methods of the various embodiments, and vice versa.

[0169] Those skilled in the art will understand that numerous variations and / or modifications can be made to the present disclosure without departing from the spirit or scope of the present disclosure as broadly described, as shown in the specific embodiments. Therefore, the present embodiments should be considered exemplary in all respects and not restrictive.

Claims

1. A circuit configured to set, during operation, first information indicating whether mapping two or more modulated symbols modulated from the information bits of a signal to two or more subcarriers is applied across two or more spatial streams of orthogonal frequency division multiplexing (OFDM) symbols, and second information indicating whether data rate adjustment is applied to the signal. A transmitting unit that, during operation, transmits the signal including the first information and the second information using the mapping of the two or more modulation symbols across the two or more spatial streams and / or the data rate adjustment, A first communication device comprising the following:

2. The two or more modulation symbols include a first pair of modulation symbols modulated from the information bits of the first signal, One symbol and the other symbol of the first pair are mapped to different spatial streams and different subcarriers within the same OFDM symbol. The first communication device according to claim 1.

3. The two or more modulation symbols include a second pair of modulation symbols modulated from information bits of a second signal different from the first signal, One symbol of the second pair is mapped to the same spatial stream as the other symbol of the first pair, and to the same subcarrier as the one symbol of the first pair. The other symbol of the second pair is mapped to the same spatial stream and the same subcarrier as the other symbol of the first pair. The first communication device according to claim 2.

4. The two or more modulation symbols include a second pair of modulation symbols modulated from information bits that duplicate the first signal, One symbol of the second pair is mapped to the same spatial stream as the other symbol of the first pair, and to the same subcarrier as the one symbol of the first pair. The other symbol of the second pair is mapped to the same spatial stream and the same subcarrier as the other symbol of the first pair. The first communication device according to claim 2.

5. Either the other symbol of the first pair or the other symbol of the second pair is mapped with its sign reversed, The first communication device according to claim 4.

6. The circuit is further configured to set the signal field of the signal, relating to either or both of the modulation coding scheme and the number of spatial streams (NSS), to include either or both of the first information and the second information. The first communication device according to claim 1.

7. The mapping includes mapping two of the two or more modulation symbols modulated from the information bits to the first subcarrier of the two or more subcarriers in the first spatial stream of the two or more spatial streams of the OFDM symbol, and to the second subcarrier of the two or more subcarriers in the second spatial stream of the two or more spatial streams, respectively. The first communication device according to claim 1.

8. The mapping includes the same mapping of two or more modulation symbols modulated from the information bits to two or more subcarriers in each of the two or more spatial streams, The first communication device according to claim 1.

9. The mapping includes mapping two of the two or more modulation symbols modulated from the first information bit of the signal to two or more subcarriers in the first spatial stream of the two or more spatial streams of the OFDM symbol and the second spatial stream of the two or more spatial streams of the adjacent OFDM symbol, and mapping two of the two or more modulation symbols modulated from the second information bit of the signal to two or more subcarriers in the second spatial stream of the two or more spatial streams of the OFDM symbol and the first spatial stream of the two or more spatial streams of the adjacent OFDM symbol. The transmitting unit transmits the signal through the first spatial stream and the second spatial stream of the OFDM symbol and the adjacent OFDM symbol. The first communication device according to claim 1.

10. The mapping further includes phase rotation, sign inversion, or conjugation of one of the two or more modulation symbols mapped to one of the two or more subcarriers in one of the two or more spatial streams of the OFDM symbol. The first communication device according to claim 8.

11. The mapping includes two switching of the two or more modulation symbols mapped to two of the two or more subcarriers in one of the two or more spatial streams. The first communication device according to claim 8.

12. The data rate adjustment corresponds to the duplication of the OFDM symbol in the payload portion of the signal, and the transmitting unit transmits the signal, which includes the OFDM symbol in the payload portion and one or more duplicates of the OFDM symbol adjacent to the OFDM symbol. The first communication device according to claim 1.

13. The data rate adjustment corresponds to the duplication of OFDM symbol blocks in the payload portion of the signal, and the transmitting unit transmits a signal that includes the OFDM symbol blocks in the payload portion and one or more duplicates of the OFDM symbol blocks adjacent to the OFDM symbol blocks, and the OFDM symbol blocks include the OFDM symbol and one or more adjacent OFDM symbols. The first communication device according to claim 1.

14. The data rate adjustment includes, in one of the one or more copies of the OFDM symbol, switching between two of the two or more modulation symbols mapped to two of the two or more subcarriers. The first communication device according to claim 12.

15. The mapping further includes phase rotation, sign inversion, or conjugation of one of the two or more modulation symbols mapped to one of the two or more subcarriers in one of the two or more spatial streams of the one or more copies of the OFDM symbol. The first communication device according to claim 12.

16. The aforementioned data rate adjustment corresponds to frequency duplication of the payload portion of the signal, The circuit is further configured to generate the signal, which includes the information bits in a first frequency segment of the payload portion of the signal and one or more copies of the information bits in one or more second frequency segments, and to set up the first information indicating whether mapping two or more modulated symbols modulated from the information bits and one or more copies of the information bits of the signal to the two or more subcarriers is applied across the two or more spatial streams of the OFDM symbols. The first communication device according to claim 6.

17. The signal field related to the modulation coding scheme indicates the number of copies of one or more copies of the information bit in one or more second frequency segments of the payload portion. The first communication device according to claim 16.

18. The second information includes the coding rate, the data rate adjustment corresponds to the formation of information bit blocks in the payload portion of the signal, and the information bit block includes a plurality of data bits. The circuit is further configured to generate the signal, which includes the information bit block and one or more parity bits in the payload portion of the signal, and to set up the first information indicating whether the mapping of two or more modulated symbols modulated from the information bit block is applied across the two or more spatial streams of the OFDM symbol. The number of parity bits (one or more) depends on the coding rate. The first communication device according to claim 1.

19. The information bit block includes either (i) one or more padding bits and (ii) one or more repetitions of the plurality of data bits, the number of padding bits and the number of repetitions of the plurality of data bits both depend on the coding rate. The first communication device according to claim 18.

20. A receiving unit that receives a signal during operation, which includes first information indicating whether mapping two or more modulated symbols modulated from the information bits of the signal to two or more subcarriers is applied across two or more spatial streams of OFDM symbols, and second information indicating whether data rate adjustment is applied to the signal. During operation, a circuit configured to decode and demodulate the signal in order to obtain information of the information bits mapped to the two or more spatial streams, A second communication device equipped with the following:

21. The signal includes a signal field relating to one or both of the modulation coding scheme and the number of spatial streams (NSS), and the signal field includes one or both of the first information and the second information. The second communication device according to claim 20.

22. Setting first information indicating whether mapping two or more modulated symbols modulated from the information bits of a signal to two or more subcarriers is applied across two or more spatial streams of OFDM symbols, and setting second information indicating whether data rate adjustment is applied to the signal, Transmitting the signal containing the first information and the second information using the mapping of the two or more modulation symbols across the two or more spatial streams and / or the data rate adjustment, A communication method implemented by a first communication device, including the above.

23. Receiving the signal which includes first information indicating whether mapping two or more modulated symbols modulated from the information bits of the signal to two or more subcarriers is applied across two or more spatial streams of OFDM symbols, and second information indicating whether data rate adjustment is applied to the signal, To obtain information of the information bits mapped to the two or more spatial streams, the signal is decoded and demodulated. A communication method implemented by a second communication device, including the above.

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