RU2775837C2 - Simplified detection of spatial modulation and space-time block encoding with selection of antennas - Google Patents

Abstract

FIELD: wireless communication.

SUBSTANCE: in the invention, AS flow encoding is performed separately in a transmitter in contrast to data flow encoding, allowing the transmitter to use one detection type (for example, ML detection) for AS bits and another detection type MIMO with decreased complexity for data bits (for example, detection with minimum min square error (MMSE) or detection with zero forcing (ZF) of insignificant coefficients).

EFFECT: reduction in complexity of processing of a set of spatially modulated flows.

20 cl, 6 dwg, 2 tbl

Description

The field of technology to which the invention belongs

The present disclosure relates to methods and systems for transmitting and receiving communication signals using spatial modulation and space-time block coding.

State of the art

The rapid increase in the number of connected devices creates a need for wireless communication networks to be able to support an ever increasing number of devices concentrated in a geographical area. The multiple heterogeneous devices that must be supported in a dense deployment scenario include, for example, high-powered devices such as personal computers and low-powered devices such as Internet of Things (IoT) devices and wearables.

Multiple Input Multiple Output (MIMO) systems that use multiple antennas can increase network performance. Spatial modulation (SM) is a MIMO type of modulation in which only a subset of the available transmit (TX) antennas of a network transmitter is activated at any given time. SM may be useful in low complexity MIMO system implementations, such as IoT and wearable messaging, and may operate in an open loop mode without requesting channel state information at the transmitter.

At least in some SM schemes, as shown for example in A. Helmy, et al., “Spatial Modulation for Improved Performance of Next-Generation WLAN”, WCNC 2017, San Francisco, CA, USA, antenna selection is made in according to the antenna selection (AS) bits that are included in a separate antenna selection stream. The AS bits are not predetermined or unknown to the receiver. Therefore, the receiver relies on the Maximum Likelihood (ML) detection type to determine the AS bits. A. Helmy et al. describe a transmitter that applies Forward Error Correction (FEC) coding for both the data streams and the AS stream together, so that as a result, the receiver must also apply the same ML detection for recovery. data stream bits. The complexity of ML detection is very high, especially for Modulation and Coding Scheme (MCS) 16-QAM or higher.

Accordingly, there is a need for an SM system capable of recovering AS and data bits received by a receiver using various detection methods.

Disclosure of the essence of the invention

This disclosure describes methods and systems that may allow, using various detection methods, to detect at the receiver the AS and data bits present in transmitted SM streams. In exemplary embodiments, AS stream coding is performed separately at the transmitter, as opposed to data stream coding, allowing the receiver to use one type of detection (eg, ML detection) for AS bits and another type of reduced complexity MIMO detection for data bits (eg, detection with Minimum Min Square Error (MMSE) or Zero Forcing (ZF) detection.

In accordance with the first approach, the method performed at the transmitter comprises the steps of: applying forward error correction (FEC) coding to encode a first portion of an incoming data bitstream into a first encoded bitstream; applying FEC encoding to encode, regardless of the first part, the second part of the incoming data bitstream into the antenna selection (AS) bitstream; encoding each of the plurality of spatial streams into corresponding symbols, each spatial stream being a different corresponding part of the first encoded bitstream; and transmitting the symbols through respective sets of transmit antennas, wherein the respective set of transmit antennas for transmitting each symbol is determined by the AS bits of the AS bitstream.

Alternatively, in any of the previous approaches, encoding each of the plurality of spatial streams into corresponding symbols comprises the steps of: encoding the bits of each of the spatial streams; converting bits of each of the spatial streams into constellation points; and transform the constellation points of each spatial stream into the corresponding symbols.

Alternatively, in any of the previous approaches, the symbols are orthogonal frequency division multiplexing (OFDM) symbols.

Alternatively, in any of the previous approaches, the AS bits are inherent in OFDM symbols on a subcarrier-to-subcarrier basis.

As an option, with any of the previous approaches, the method is designed to generate and transmit data block data protocol (Protocol Data Unit, PPDU) physical layer convergence procedure (Physical Layer Convergence Procedure, PLCP), and the method further comprises the step of: enter into a PPDU preamble; where the total number of transmit antennas NT is greater than the number N of transmission streams used to transmit the PPDU data.

Alternatively, in any of the previous approaches, the symbol pilot subcarriers are mapped to the respective transmit antenna sets according to the AS bits.

According to another approach, the processing system comprises a memory and a processing device coupled to the memory, the processing device being configured to: apply Forward Error Correction (FEC) coding to encode a first portion of an incoming data bitstream into a first encoded bitstream; applying FEC encoding to encode, regardless of the first part, the second part of the incoming data bitstream into the antenna selection (AS) bitstream; encoding each of the plurality of spatial streams into corresponding symbols, each spatial stream being a different corresponding portion of the first encoded bitstream; and transmitting the symbols through respective sets of transmit antennas, wherein the respective set of transmit antennas for transmitting each symbol is determined by the AS bits of the AS bitstream.

Alternatively, in any of the previous approaches, the processor is configured to encode each of the plurality of spatial streams into corresponding symbols by:

encoding bits in each of the spatial streams; converting bits of each of the spatial streams into constellation points; and converting the constellation points of each spatial stream into corresponding symbols.

Alternatively, in any of the previous approaches, the symbols are orthogonal frequency division multiplexing (OFDM) symbols.

Alternatively, in any of the previous approaches, AS bits are inherent in OFDM symbols on a subcarrier-to-subcarrier basis.

Alternatively, with any of the previous approaches, the processing device is configured to generate a Physical Layer Convergence Procedure (PLCP) protocol data unit (Protocol Data Unit, PPDU) using coding, and transmit the PPDU through the corresponding sets of transmit antennas , using the transmission, and the processing device is further configured to: input in the preamble PPDU many long training fields (long training field, LTF), in which the number of LTF in the preamble corresponds to the total number of NT transmit antennas; wherein the total number NT of transmit antennas is greater than the number N of transmission streams used to transmit the PPDU data.

Alternatively, in any of the previous approaches, the pilot symbol subcarriers are mapped to the respective transmit antenna sets according to the AS bits.

In accordance with another approach, a method for processing a plurality of spatially modulated streams, each of which is received through a plurality of antennas in the receiver, comprises the steps of: applying detection based on the logarithmic likelihood ratio (Log Likelihood Ratio, LLR) for maximum likelihood (Maximum Likelihood , ML), to spatially modulated streams for antenna selection (AS) bit detection; applying MIMO (multiple input multiple output) type detection to separate the SM modulated streams into respective streams for decoding, where the MIMO detection is based on the detected AS bits and uses a detection other than ML based detection; and decode the corresponding streams.

Alternatively, in any of the preceding approaches, decoding comprises: performing an inverse constellation transform; and performing bit-reversal.

Alternatively, with any of the previous approaches, MIMO detection is performed using Minimum Min Square Error (MMSE) detection or Zero Forcing (ZF) detection.

Alternatively, with any of the previous approaches, ML LLR AS bit detection is performed using a calculation of the Euclidean distance between received spatially modulated streams and a binary phase shift keying (BPSK) constellation.

According to a further approach, the processing system comprises a memory and a processing device associated with the memory. The processor is configured to apply detection based on a Log Likelihood Ratio (LLR) for Maximum Likelihood (ML) to a plurality of spatially modulated streams received by a plurality of receive antennas to detect antenna selection (AS) bits; applying detection with multiple inputs and multiple outputs (multiple input multiple output, MIMO) to separate the SM modulated streams into corresponding streams for decoding, in which the MIMO detection is based on the detected AS bits and uses a detection other than detection based on ML; and decoding the respective streams.

Alternatively, in any of the prior approaches, the processor is further configured to perform decoding by: performing an inverse constellation transform; and performing bit-reversal.

Alternatively, in any of the previous approaches, MIMO detection is performed using Minimum Min Square Error (MMSE) detection or Zero Forcing (ZF) detection.

Alternatively, in any of the previous approaches, ML LLR-based AS bit detection is performed by calculating the Euclidean distance between the received spatially modulated streams and a binary phase shift keying (BPSK) constellation.

In some approaches, the present disclosure describes a processing system comprising a memory and a processing device associated with the memory. The processing device is configured to implement any of the preceding methods.

Brief description of the drawings

Reference will now be made by way of example to the accompanying drawings showing exemplary embodiments of the present application and in which:

Fig. 1 is an example of a radio frequency communication network in which exemplary embodiments may be implemented;

Fig. 2 is a block diagram of an exemplary apparatus suitable for transmission or reception in a radio frequency communication network;

Fig. 3 is a block diagram of a transmitter according to the first exemplary embodiment;

Fig. 4 is a block diagram of a receiver according to the first exemplary embodiment;

Fig. 5 is a block diagram of a transmitter according to the second exemplary embodiment; and

Fig. 6 is a block diagram of a receiver according to the second exemplary embodiment.

Like reference numerals may be used throughout the drawings to refer to like components.

Implementation of the invention

The following is a table of selective abbreviations used in the following description:

Table 1

Abbreviations

Reduction Definition STA Station AP Access point SM Spatial modulation AS Antenna selection ML Maximum Likelihood FEC Forward Error Correction MCS Modulation and coding system MIMO Multiple inputs to multiple outputs MMSE Minimum RMS error ZF Vanishing Insignificant Coefficients STBC Spatio-temporal block coding TX Transmitter RX Receiver LLR Log likelihood ratio QAM Quadrature amplitude-shift keying ChanD, Channel D Channel D; one of the IEEE channel models BCC Binary Convolutional Encoding LDPC Low Density Parity Check

In FIG. 1 is a schematic diagram of an exemplary system 100 in which the methods described herein may be implemented. System 100 represents the network infrastructure of a local wireless network, which may be, for example, a Wi-Fi infrastructure containing an access point (AP) 102. AP 102 may also be referred to as a Personal Basic Service Set control point, PBSS) (PCP) or base station. AP 102 may be implemented as a router, for example. In general, the designation AP 102 may refer to any component (or set of components) capable of providing wireless access to a network, such as an deployed NodeB (eNB), a macro cell, a femto cell, a distribution node, a Wi-Fi AP, or other devices operating using wireless technologies. The AP 102 may, for example, provide wireless access in accordance with one or more wireless communication protocols, such as Long Term Evolution (LTE), LTE-Advanced (LTE-A), High Speed Packet Access (HSPA), Wi-Fi 802.11a/b/g/n/ac/ad and other 802.11 protocols. At least one station (STA) 104 communicates with AP 102. In configurations in which multiple STAs communicate with AP 102, each STA 104 may operate independently with different capabilities. STA 104 may also be referred to as, for example, a terminal, user device, user equipment (UE), or client. Each STA 104 may be any component (or set of components) capable of wireless communication, such as any suitable electronic device (ED) capable of wireless communication, including mobile or stationary devices such as smartphones, laptops, mobile phones, Internet of Things (IoT) devices, wearable devices, tablet devices, or any other device capable of wireless communication, and the STA 104 need not be the same.

System 100 may support communication between AP 102 and each STA 104, as well as communication directly between STA 104 (also referred to as device-to-device communication). STA 104 may also serve as a relay station for STA to STA or AP to STA communications. AP 102 may also perform multi-user (MU) transmissions (eg, transmissions from AP 102 to many STA 104 at the same time), for example, using directional antennas and/or frequency division. In the example in FIG. 1, system 100 supports MIMO communication between AP 102 and STA 104, allowing multiple spatially modulated (SM) RF streams 106(1)-106(N) (each generically referred to as SM stream 106) to be sent. signals from AP 102 to STA 104 at the same time.

In FIG. 2 shows a block diagram of a simplified exemplary processing system 200 that may be used to implement the embodiments disclosed herein. The exemplary processing system 200 described below, or variations thereof, may be used to implement the AP 102 or any of the STAs 104. Other processing systems may be suitable for implementing the embodiments described in this disclosure and may contain components other than those discussed below. Although in FIG. 2 shows only one instance of each component, there may be multiple instances of each component in processing system 200.

The processing system 200 may comprise one or more processing devices 202 such as a processor, a microprocessor, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), an application-specific logic circuit, or their combinations. Processing system 200 may further comprise one or more input/output (I/O) interfaces 204 to allow interaction with one or more additional input devices 214 and/or output devices 216. Processing system 200 may include one or more network interfaces 206 for wired or wireless communication with a network (eg, intranet, Internet, P2P, WAN, and/or LAN) or another node. The network interface(s) 206 may include wired links (eg, an Ethernet cable) and/or wireless links (eg, one or more antennas) for intranet and/or internetwork connections.

Network interface(s) 206 may provide wireless communications via one or more antennas. In this example, the plurality of antennas together form an antenna array 218 that can perform both transmit and receive functions. Antenna array 218 may allow directional communication using beamforming and beamtracking. In other examples, there may be separate antennas or separate antenna arrays for transmit and receive.

The processing system 200 may also include one or more storage devices 208, which may include a mass storage unit such as a solid state drive, a hard drive, a magnetic disk, and/or an optical disk. Processing system 200 may include one or more memories 210, which may include volatile or nonvolatile memory (eg, flash memory, random access memory, RAM, and/or read-only memory, ROM). The non-portable memory(s) 210 may store instructions for execution by the processing device(s) 202 so as to perform the exemplary methods described in this disclosure. The memory(s) 210 may contain other software instructions, such as to implement an operating system and other applications/functions. In some examples, one or more datasets and/or modules may be provided by external storage (eg, an external drive in wired or wireless communication with processing system 200) or may be provided by portable or non-portable computer-readable media. Examples of non-portable computer-readable media include RAM, ROM, erasable programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), flash memory, CD-ROM, or other portable memory storage devices.

Possible bus 212, providing communication between the components of the system 200 processing, containing device(s) 202 processing, additional interface(s) 204 I/O, network interface(s) 206, block(s) 208 storage device and/ or memory(s) 210. Bus 212 may be any suitable bus architecture, including, for example, a memory bus, a peripheral bus, or a video bus.

In FIG. 2 additional input device(s) 214 (eg, keyboard, mouse, microphone, touch screen, and/or keyboard) and additional output device(s) 216 (eg, display, speaker, and/or printer) are shown as external in relation to the processing system 200. In other examples, one or more input devices 214 and/or output devices 216 may be an internal component of the processing system 200.

In FIG. 3 shows a block diagram of a transmitter 300 implemented by AP 102 processing system 200 in accordance with exemplary embodiments. The transmitter 300 includes a first group of transmitter blocks 302 that correspond to the transmitter blocks specified in IEEE 802.11-2016 clause 19: High-Throughput (HT) PHY specifications. In the embodiment of FIG. 3, in addition to the first transmitter block group 302, the transmitter 300 also includes a transmitter block antenna selection (AS) group 304 which, as described below, allows the AS bits to be encoded separately from the data bits that are encoded by the first transmitter block group 302.

In the illustrated embodiment, the first transmitter block group 302 comprises operational processes represented by the following blocks: a) scrambler (block 306): scrambles input data (incoming interleaved bit stream I) to reduce the likelihood of long sequences consisting of 0s or 1s; b) encoder parser (block 308): if binary convolutional coding (BCC) is to be used, this block demultiplexes the scrambled bits among N _ES (the number of BCC encoders for the data field). The BCC encoders round-robin, also as described below, separate the data bits for use as antenna selection (AS) bits from among the scrambled bits; c) FEC encoders (block 310): encode data to allow error correction (the FEC encoder may comprise a BCC encoder followed by a puncher or may comprise a low density parity check (LDPC) encoder); d) a stream parser (block 312) divides the encoder outputs from the FEC 310 into spatial streams that are sent to various interleavers and converters; e) interleaver (block 314): interleaves the bits of each spatial stream (reverses the bit order) to prevent long sequences of adjacent noise bits (interleaving can only be applied when BCC coding is used); f) constellation converter (block 316): converts the sequence of bits in each spatial stream into constellation points (complex numbers); g) space-time block coding (STBC) encoder (block 318): distributes constellation points of N _ss spatial streams into N _sts space-time streams using a space-time block code (STBC can only be used when N _ss <Nsts); h) Cyclic shift diversity (CSD) block (block 320): inserts a cyclic shift into the space-time stream to prevent random beamforming; i) spatial transform block (block 322): transforms the space-time streams to transmit strings; j) inverse discrete Fourier transform (IDFT) block (block 324): transforms the block of constellation points into a block in the time domain; k) Guard interval (GI) windowing and insertion box (block 326): GI insertion adds GI to the beginning of the symbol with its own circular extension, the windowing operation further smoothes the edges of each symbol to increase spectral attenuation; i) analog and RF block (block 328): upconverts the subcarriers to a carrier frequency and transmits the resulting upconverted stream to the wireless channel via the corresponding transmit antenna TA(1)-TA(N _T ) (referred to generically as the transmit antenna TA or transmitting antennas TA(i)).

The first group 302 of transmitter units is configured to generate a Data field (Data) of Protocol Data Units (PPDUs) of a Physical Layer Convergence Procedure (PLCP). A subset of transmitter block group 302, containing the constellation transform (block 316), CSD (block 320), spatial transform block (block 312), and transmission chains, is also used to form the preamble fields of PPDUs containing High Throughput Long Training Field, HT-LTF).

In exemplary embodiments, depending on the particular application, some of the transmitter processing blocks in the first group 302 may be omitted. For example, in some transmitter configurations where BCC coding is not used, multiple FEC encoders 310 of the data stream may be replaced by a single FEC encoder 310. In some examples, STBC block 318 may be omitted.

The present disclosure applies to applications where the transmitter 300 is configured to generate a plurality (N) of space-time streams less than the number of N _T transmit antennas TA(i) available at the transmitter 300 and use an N subset of the N _T transmit antennas TA(i) to transmit N SM streams 106(1)-106(N). In the exemplary embodiment to be now described, the number N of space-time streams generated in a given time by transmitter 300 is equal to the number of spatial data streams, as well as the number of transmitted SM streams 106(1)-106(N), and block 318 The STBC of transmitter 300 may be omitted. Since the number (N) of transmission chains and respective transmit antennas TA(i) used to transmit the SM streams 106 is less than the total number (N _T ) of transmission chains and antennas, the spatial transform block 322 requests commands as to which antennas must be chosen. The selection of antennas by spatial transform block 322 is done based on "OFDM subcarrier-OFDM subcarrier".

In an exemplary embodiment, when generating a PPDU data field, transmitter 300 receives as input an I bitstream that contains a data bitstream. Selected bits from the data stream are used by transmitter 300 as antenna select (AS) bits. These AS bits are used to determine which of the N _T transmit antennas TA(i) (and corresponding transmission chains) should be used to transmit the respective SM streams 106. antenna selection, the bits that are used to select antennas have the dual purpose of transmitting data as well as providing information about antenna selection.

Accordingly, in exemplary embodiments, the encoder parser 308 is configured to split the incoming bit stream I data into one or more spatial data streams and a separate AS stream 305 . The one or more spatial data streams together comprise mN bits/OFDM symbol/subcarrier, where N is the number of spatial streams and m=log ₂ (M), where M is the size of the signal constellation alphabet that is applied in the constellation transform blocks (block 316). The AS stream 305 contains n bits/OFDM symbol/subcarrier, where n is the number of active antenna section bits used to provide an index value that determines which of the N _T antennas is selected. The AS bits of stream 305 are sent to transmitter block AS group 304 for separate processing, and the data streams are sent to the FEC encoder(s) (block 310) and stream parser (block 312) in the first transmitter block group 302 to form N spatial data streams, each of which undergoes respective operations of the interleaver (block 314) and the constellation transform block (block 316), resulting in the input of N respective space-time data streams into the spatial transform block (block 322).

Referring again to the AS stream 305, the parsing process used by the encoder parser (block 308) to selectively extract the n bits/OFDM symbol/subcarrier for the AS stream 305 from the incoming everyday data stream I can be any suitable predetermined parsing process. In FIG. The 3 AS bits that are output by the encoder parser 308 are identified as the original AS bits. The transmitter block AS group 304 processes the AS stream 305 to convert the original AS bits into processed AS bits and AS selection information, which are then used for antenna selection and subcarrier coding by the spatial mapper (block 322). In particular, a separate FEC encoding operation is applied by a particular FEC AS encoder (block 330) of the AS stream to the original AS bits of the AS stream 305 . Thus, the AS bitstream is FEC coded in the AS FEC encoder (block 330) regardless of the data bitstream(s) that are FEC coded in the encoders (blocks 310) of the first transmitter block group 302.

The FEC-coded AS bits are then interleaved at the AS interleaver (block 332), resulting in processed AS bits. An antenna selection operation (block 334) is then applied to the encoded, interleaved AS bits (where the encoded, interleaved bits are processed AS bits) to determine based on the AS bits contained in the AS stream 305 received from antennas TA(1)-TA( N _T ) to use. The antenna selection operation (block 334) may, for example, be based on a lookup table. An exemplary embodiment of an antenna selection lookup table in which the number of SM streams is N=2, the number of available transmit antennas is N _T =4, and the number of active AS bits is n=2 is as follows.

table 2

Antenna selection table

Index of selected antenna combination Two data bits corresponding to each selected antenna combination (1st bit, 2nd bit) Selected set of TX antennas
(1st TA, 2nd TA) 0 (0, 0) [TA 0, TA 1] one (0, 1) [TA 2, TA 3] 2 (ten) [TA 0, TA 3] 3 (eleven) [TA 1, TA 2]

In exemplary embodiments, information identifying the selected set of antennas (e.g., column 3 of Table 1) is provided to a spatial transformation process (block 332), which converts the constellation points from the N space-time data streams directly into the corresponding transmission chains of the selected transmit antennas TA(i ). In the above example, in which the number of AS bits is two, the two processed AS bits are used to select two TX antennas for each subcarrier. Then, the resulting SM streams 106(1)-106(N) are transmitted. In at least some embodiments, pilot subcarriers that otherwise cannot be used for data transmission can be used to carry actual data via the AS bits because the TX antenna selection for the pilot subcarriers must also be made by the AS bits.

As noted above, a subset of transmitter 300 blocks is used to form the HT-LTF containing portion of the PPDU preamble that precedes the data field. In multi-transmit antenna situations, the number of HT-LTFs contained in the PPDU before the data field is typically determined by the number of active transmission streams. However, in the present embodiments, the receiving device (eg, STA 104) does not know in advance which of the transmit antennas TA(1)-TA(N _T ) will actually be used to transmit the SM streams 106, and accordingly requests information for estimates of all possible N _T channels of SM-flows. Accordingly, when transmitter 300 collects a PPDU, it must contain enough HT-LTF to allow the receiver to estimate all possible N _T SM channels. As an example, when N _T =4, then 4 HT-LTFs should be included in the PPDU preamble. Although this may increase the amount of overhead required for channel estimation in some applications, when compared to other MIMO-based spatial multiplexing systems, as noted above, in the exemplary embodiments, the AS bits that are transmitted in the SM streams 106 are carried as data. , and antenna selection information, thus improving performance by an additional n bits per subcarrier for each OFDM symbol.

As shown in FIG. 4, transmitted SM streams 106(1)-106(N) are received at receiver 400 as received SM streams 106R(1)-106R(N), respectively. The receiver units shown in FIG. 4 represent processing operations that, for example, can be implemented by the processing system 200 on the STA 104. As shown in FIG. 4, receiver 400 includes N _R receive antennas. Each of the N _R receive antennas receives all N SM streams 106R(1)-106R(N). Receiver 400 includes receiver (RX) processing operations (block 402) that filters and downconverts to baseband the SM streams 106R(1)-106R(N) received by each receive antenna. As shown at block 404, GI removal is applied to the symbols in the received baseband streams and a fast Fourier transform is applied to transform the symbols into the frequency domain. In addition, the N _T HT-LTF signals contained in the received streams are used to perform channel estimation for each of the possible N _T x N _R RF channels between receiver 400 and transmitter 300. The antennas selected at the transmitter essentially communicate via SM streams 106R(1)-106R(N) and ML LLR calculations are performed to extract AS information. In particular, as indicated at block 406, LLR calculations are performed to estimate the AS bits specific to received streams 106R(1)-106R(N). For example, in a case where two of the 4 possible antennas are used, ML-based LLR is performed according to all combinations of antenna selection for the first bit 0 or 1 and the second bit 0 or 1. The probability for bit 0 minus the probability for bit 1 would be LLR in the corresponding bit like the first AS bit (or the second AS bit) for each subcarrier. The LLR for AS bits is obtained by taking the logarithm of the sum of multiple exponentials. The sum of the exponentials can be approximated by finding the maximum value of the exponent of the exponentials, which can be shown as below [1].

Equation 1:

where:

является LLR для i-ого выбора бита антенны, когда принятый сигнал является вектором y через потоки RX 106R(1)-106R(N) и

является канальной матрицей для выбранного набора антенны.

is the LLR for the ith antenna bit selection when the received signal is a y vector via RX streams 106R(1)-106R(N) and

is the channel matrix for the selected antenna set.

является выбором выбранного бита антенна и

является набором антенных конфигурации, когда i-ый выбор антенного бита равен 0.

is the choice of the chosen bit antenna and

is the antenna configuration set when the i-th antenna bit selection is 0.

является набором констелляций QAM, и

is a set of QAM constellations, and

- полный набор констелляций QAM, где набор констелляций QAM является двумя элементами полного набора констелляций QAM, например, в случае 2 потоков, выбранных из возможных 4 потоков, набор констелляций QAM является двумя из 16 точек констелляций QAM всего набора констелляций QAM.

- the complete QAM constellation set, where the QAM constellation set is two elements of the complete QAM constellation set, for example, in the case of 2 streams selected from a possible 4 streams, the QAM constellation set is two of the 16 QAM constellation points of the entire QAM constellation set.

The number of output LLRs per subcarrier is determined by the number of bits used to select the TX antennas. Thus, according to the example shown in Table 1 where N = 2, there will be two output LLRs per subcarrier from block 406. In the example of FIG. 4, the LLR output signals are soft decision information that is processed by the antenna configuration block 408 . In this regard, the outputs of the non-strict LLR decision for the antenna selection bits are de-interleaved (block 410) to de-transform the AS interleaving performed in the transmitter AS interleaver 332 and then pass through the AS FEC decoder 412 to recover the AS bits that were originally inputted. to the 330 AS FEC transmitter encoder. Accordingly, the output of the FEC AS decoder 412 is a reconstructed version of the AS bits that were originally provided as input (original AS bits) to the AS stream group 305 of transmitter blocks.

As shown in FIG. 4, the recovered AS bits are then re-encoded and re-interleaved to recreate the processed AS bits, and these recreated processed AS bits are used to make the final AS selection decision (block 414). In particular, the operations performed in block 414 on the recovered AS bits are the same as those performed by transmitter block AS group 304 on the original AS bits, resulting in a reconstructed version of the processed AS bits and AS information that was generated by group 304 AS transmitter blocks. Receiver 400 thus has a local copy of the antenna selection information shown in Table 1 for use.

The resulting antenna selection information is then subjected to a MIMO discovery process (block 416) (As noted above, STBC is excluded from this example and will be discussed in the context of a further example below). MIMO detection is performed on the baseband SM streams to recover the N spatial streams. This MIMO discovery is done with an understanding of which hop antennas were used for the OFDM symbols. The N recovered spatial streams may then be processed in parallel using the operations of the respective constellation demappers and bit deinterleaver (blocks 418) and the resulting data streams are deparsed and decoded with FEC (block 420) for the deparsing of the stream and encoding processes. with FEC, which were performed in blocks 312, 310 of the transmitter. A decoder de-parsing operation (block 422) is then performed to recombine the recovered AS bitstream with the recovered data bitstream by de-parsing the parsing performed at transmitter block 308 . Finally, a descrambler operation (block 424) is applied to generate output data stream O, which is a reconstructed version of input data stream I.

As noted above, MIMO detection (block 416) may be performed with full knowledge of the transmission channels based on antenna selection performed by antenna configuration block 408 . This reduces the channel coefficient matrix H for data detection from SM streams 106R(1)-106R(N) from N _T x N _R to N x N _R , where N <N _T . Accordingly, by allowing the AS stream to be processed independently of the data streams at the receiver 400, the system shown in FIG. 3 and 4 allows the receiver to know which transmit antennas were used prior to decoding the data streams. This, in turn, allows a simpler discovery process to be used to recover individual spatial streams from the SM streams 106R(1)-106R(N) and subsequently decode the data in the streams. For example, the MIMO detection applied at block 416 may be based on a less resource intensive detection algorithm such as MMSE or ZF rather than the more resource intensive ML based on LLR calculation. If MMSE or ZF detection is used, the LLR calculation can then be performed on a per-stream basis using a smaller matrix H of channel coefficients.

With respect to the LLR calculations performed on the AS bits (block 406), as noted above, the LLR outputs for each subcarrier are determined by the number of bits used to select the TX antennas. Although ML-based LLR calculation is used in receiver 400 to detect AS bits, this is only required for a subset of bits (eg, the number of AS bits) for each subcarrier, and not for all bits, including AS bits and data.

Thus, using separate AS bit FEC specific encoder operations and AS interleaver (blocks 332, 334) at transmitter 300 and corresponding AS bit specific operations at receiver 400 allows processing of the AS bit stream (which contains bits carrying AS information, as well as data) independently of data bit streams (which contains only data bits), allowing different detection methods to be applied to each stream. Detection performed on data bitstreams can be done with knowledge of the choice of transmitting antennas, which is obtained from the AS bitstream.

In exemplary embodiments, STBC may be applied by transmitter 300 and corresponding STBC detection may be performed at receiver 400. STBC adds an extra layer of processing at the transmitter and receiver since N spatial streams are not directly mapped to N space-time streams. The use of STBC can provide a diversification gain by using more transmission chains and transmit antennas than the number of existing spatial streams.

In FIG. 5 is a block diagram of a transmitter 500 implemented by AP 102 processing system 200 in accordance with a further exemplary embodiment. The operation blocks of the transmitter 500, which have the same function as those of the transmitter 300, are denoted by the same reference numerals as in FIG. 3. The only difference between transmitter 500 and transmitter 300 is that the data bits from the input I stream that are used for the AS bits are not extracted from the input data bit stream I until FEC encoding occurs. In this respect, as shown in FIG. 5, the parser bit operation (block 511) occurs after the input data bitstream I has been scrambled (block 306) and FEC encoded (block 310). In the parser bit operation (block 511), the data bits that are used for antenna selection (labeled as raw AS bits in FIG. 5) are extracted into the AS stream 505 from the rest of the data bitstream. The bitstream data is parsed (block 312) into N parallel spatial data streams, which are interleaved, constellated and CSD transformed (blocks 314, 316, 320) and provided to the spatial transformation process (block 322).

The original AS bits in AS stream 505 are processed by the AS interleaver and subjected to antenna selection operations (blocks 332 and 334) in the same manner as described above with respect to transmitter 300 to provide the processed AS bits and AS information for the spatial transformation process (block 322 ). The spatial mapping process (block 322) transforms the respective spatial data streams into the respective transmission chains as indicated by the AS information, and also encodes each subcarrier with the processed AS bits, resulting in SM transmission streams 506(1)-506(N).

As shown in FIG. 6, transmitter 500 requests receiver 600, which has a different receiver configuration than receiver 400, to receive SM streams 506R(1)-506R(N). This is because joint FEC encoding of the AS bits and data bits only before parsing at transmitter 500 makes it difficult for the receiver to perform a separate process of decoding and re-encoding just for the AS bits, as is done at receiver 400. FIG. 6, the operating blocks of the receiver 600, which have the same function as those in the receiver 400, have the same reference numerals as used in FIG. four.

The receiver 600 differs from the receiver 400 in that the antenna configuration block 408 of the receiver 400 (which contains the deinterleaver AS and decoder with FEC processes (blocks 410, 412) and the recoding, reinterleaving, and antenna selection processes (block 414) are all replaced at receiver 600 to a simple hard decision antenna selection process (block 608). Accordingly, at receiver 600, a hard decision for AS is made immediately after the calculation of the LLR (block 406 using equation (1)) for the AS bits. As a result of hard decision, the detection process MIMO (block 416) becomes aware of the selected transmit antennas used in transmitter 500 and MIMO detection should not be limited to ML-based LLR calculation, but may alternatively use less computationally intensive detection algorithms such as MMSE and ZF If MMSE detection is used or ZF, the LLR calculation is processed for each spatial data stream individually.

В некоторых примерах обнаружение MIMO (блок 416) может быть сделано, основываясь на вычислении LLR на основе ML. Например, вычисление LLR, основанное на ML, может быть выполнено для всех возможных сочетаний конфигураций антенн – в случае, когда передающие антенны определяются до обнаружения MIMO, количество сочетаний антенн становится меньше, чем когда передающие антенны не были определены. Как пример определения MIMO, вычисление LLR, основанное на ML, для потоков данных приводится ниже в уравнении (2).

In some examples, MIMO detection (block 416) may be done based on the ML based LLR calculation. For example, an ML-based LLR calculation can be performed for all possible combinations of antenna configurations - in the case where transmit antennas are determined prior to MIMO detection, the number of antenna combinations becomes less than when no transmit antennas were determined. As an example of the definition of MIMO, the calculation of LLR based on ML for data streams is given below in equation (2).

Equation 2:

LLR для q-го бита переданных данных, когда принимаемый сигнал является вектором y через потоки RX и

является канальной матрицей для выбранного набора антенн

LLR for the qth transmitted data bit when the received signal is a y vector via the RX streams and

is the channel matrix for the selected set of antennas

Выбор бита выбранных антенн

Bit Selection of Selected Antennas

S : Set of all antenna configurations

Набор констелляций QAM

QAM constellation set

Набор констелляций QAM для q-го бита передаваемых данных, 1.

A set of QAM constellations for the q-th bit of transmitted data, 1.

As noted above, in exemplary embodiments, the AS bits may be applicable even to pilot carriers that are not normally used for information transmission. When pilot carriers are transmitted through antennas selected by the AS bits, the LLR calculation for the antenna selection bits can be done by calculating the Euclidean distance between the received signal and the binary phase shift keying (BPSK) or quadrature BPSK (quadrature BPSK, QBPSK) constellation, regardless of the MCS for the information bits of the data field.

While the present disclosure describes methods and processes with steps in a specific order, one or more steps of the methods and processes may be omitted or changed as needed. One or more of the steps, as appropriate, may take place in an order other than the order in which they are described.

While the present disclosure has been described at least in part in terms of methods, those skilled in the art will appreciate that the present disclosure also relates to various components for performing at least some of the approaches and features of the described methods via hardware, software, security or any combination thereof. Accordingly, the technical solution of the present disclosure may be implemented in the form of a software product. The desired software product may be stored as a pre-recorded storage device or other similar non-volatile or non-transferable computer-readable media, including, for example, a DVD, CD-ROM, USB flash drive, removable hard drive, or other media. The software product contains instructions physically stored thereon that enable a processing device (eg, a personal computer, server, or network device) to execute examples of the methods disclosed herein.

The present disclosure may be embodied in other specific forms without departing from the subject matter of the application. The exemplary embodiments described are to be considered in all respects to be illustrative only and non-limiting. Selected features of one or more of the embodiments described above may be combined to create alternative embodiments not expressly described, and features suitable for such combinations should be understood to be within the scope of this disclosure.

All values and subranges within the disclosed ranges are also disclosed. Furthermore, while the systems, devices, and processes disclosed and shown herein may contain a number of elements/components, the systems, devices, and assemblies may be modified to contain additional or fewer such elements/components. For example, while any of the disclosed elements/components may be referred to as a single one, the embodiments disclosed herein may be modified to include multiple such elements/components. The subject matter described here is intended to encompass and contain all necessary changes in technology.

Claims (42)

1. The method implemented by the transmitter and containing the steps in which: applying Forward Error Correction (FEC) coding to encode a first portion of an incoming data bitstream into a first encoded bitstream; applying FEC coding to encode, regardless of the first part, the second part of the incoming data bitstream into the antenna selection (AS) bitstream; encoding each of the plurality of spatial streams into corresponding symbols, each spatial stream being a different corresponding part of the first encoded bitstream; and transmitting the symbols through respective sets of transmit antennas, wherein the corresponding set of transmit antennas for transmitting each symbol is determined by the AS bits of the AS bitstream. 2. The method of claim 1, wherein the step of encoding each of the plurality of spatial streams into corresponding symbols comprises sub-steps of: encode the bits in each of the spatial streams; converting the bits in each of the spatial streams into constellation points; and transform the constellation points of each spatial stream into the corresponding symbols. 3. The method of claim 1 or 2, wherein the symbols are orthogonal frequency division multiplexing (OFDM) symbols. 4. The method of claim 3, wherein the AS bits are inherent to the OFDM symbols on a subcarrier-to-subcarrier basis. 5. The method according to any one of paragraphs. 1-4, characterized in that it is intended for the formation and transmission of data of the Protocol Data Unit (PPDU) of the Physical Layer Convergence Procedure (PLCP), and additionally containing a step at which a plurality of long training fields (LTFs) are included in the PPDU preamble, and the number of LTFs in the preamble corresponds to the total number of N _T transmit antennas; wherein the total number N _T of transmit antennas is greater than the number N of transmission streams used to transmit the PPDU data. 6. The method according to any one of paragraphs. 1-5, in which the symbol pilot subcarriers are mapped to the respective transmit antenna sets according to the AS bits. 7. A processing system comprising a memory and a processing device connected to the memory, the processing device being configured to: applying Forward Error Correction (FEC) coding to encode a first portion of the incoming data bitstream into a first encoded bitstream; applying FEC encoding to encode, regardless of the first part, the second part of the incoming data bitstream into the antenna selection (AS) bitstream; encoding each of the plurality of spatial streams into corresponding symbols, each spatial stream being a different corresponding part of the first encoded bitstream; and transmitting symbols through respective sets of transmit antennas to transmit each symbol determined by the AS bits of the AS bitstream. 8. The processing system of claim 7, wherein the processor is configured to encode each of the plurality of spatial streams into corresponding symbols by: encoding bits into each of the spatial streams; converting bits of each of the spatial streams into concentration points; and transformation of the concentration points of each of the spatial streams into the corresponding symbols. 9. The processing system of claim 7 or 8, wherein the symbols are orthogonal frequency division multiplexing (OFDM) symbols. 10. The processing system of claim 9, wherein the AS bits are inherent to the OFDM symbols on a subcarrier-to-subcarrier basis. 11. The processing system according to any one of paragraphs. 7-10, in which the processing device is configured to generate protocol data unit (PPDU) data of a physical layer convergence procedure (PLCP) using encoding, and transmitting the PPDU through the respective sets of transmit antennas using transmission, and the processing device is further configured with opportunity: including a plurality of long training fields (LTFs) in the PPDU preamble, the number of LTFs in the preamble corresponding to the total number of N _T transmit antennas; wherein the total number N _T of transmit antennas is greater than the number N of transmission streams used to transmit PPDU data. 12. The processing system according to any one of paragraphs. 7-11, in which the symbol pilot subcarriers are mapped to the respective transmit antenna sets according to the AS bits. 13. A method for processing a plurality of spatially modulated streams, each of which is received by a receiver through a plurality of antennas, comprising the steps of: apply detection based on log-likelihood ratio (LLR) for maximum likelihood (ML) to the spatially modulated streams to detect antenna selection (AS) bits; using multiple input-multiple output (MIMO) detection to separate the SM modulated streams into respective streams for decoding, the MIMO detection being based on the detected AS bits and using a detection other than detection based on ML detection; and decode the corresponding streams. 14. The method according to p. 13, in which the step of decoding contains sub-steps, which perform the inverse transformation of the constellation; and perform bit-reversal. 15. The method of claim 13 or 14, wherein the MIMO detection is performed using minimum mean square error (MMSE) detection or zero-to-zero (ZF) detection. 16. The method according to any one of paragraphs. 13-15, in which ML LLR type detection for AS bits is performed using a calculation of the Euclidean distance between received spatially modulated streams and a binary phase shift keying (BPSK) constellation. 17. A processing system comprising a memory and a processing device connected to the memory, the processing device being configured to: applying detection based on the maximum likelihood (ML) logarithmic likelihood ratio (LLR) to a plurality of spatially modulated streams to detect antenna selection (AS) bits; applying multiple input multiple output (MIMO) detection to separate the SM modulated streams into respective streams for decoding, wherein the MIMO detection is based on the detected AS bits and uses a detection other than detection based on ML detection; and decoding the corresponding streams. 18. The processing system of claim 17, wherein the processing device is further configured to decode by performing an inverse constellation transform and performing bit deinterleaving. 19. The processing system of claim 17 or 18, wherein the MIMO detection is performed by minimum mean squared error (MMSE) detection or zeroing (ZF) detection. 20. The processing system according to any one of paragraphs. 17-19, in which ML LLR AS bit detection is performed by calculating the Euclidean distance between the received spatially modulated streams and a binary phase shift keying (BPSK) constellation.

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