JP2007506303A - Multi-antenna system and method using high-throughput space-frequency block codes - Google Patents

Abstract

  Multi-carrier transmitters use high-throughput space-frequency block codes and map transmission symbols to specific transmit antennas and specific subcarriers of a multi-carrier communication channel.

Description

  The present invention relates to wireless communications and, in some embodiments, to multi-carrier communication systems.

CROSS REFERENCE TO RELATED APPLICATIONS This application is a 35 U.S. S. C. 119 (e) claims the benefit of priority, which is incorporated herein for reference.

  To increase the data rate and / or throughput of wireless communications, wireless signals are transmitted using two or more transmit antennas over two or more spatial channels utilizing subcarriers of the same frequency. These systems are often referred to as multi-input multi-output (MIMO) systems and take advantage of multipath diversity between antennas. Conventional MIMO systems encode signals using convolutional coding and / or Viterbi coding, but these techniques are sensitive to antenna separation and antenna fading correlation.

  Accordingly, there is a general need for an apparatus and method for increasing the data rate and / or throughput of wireless communications.

  The appended claims are directed to some of the various embodiments of this invention. When considered in conjunction with the drawings, the detailed description may provide a more thorough understanding of the embodiments of the invention, with like reference numerals referring to like items throughout the drawings.

  The following description and drawings sufficiently illustrate certain embodiments of the invention to enable those skilled in the art to practice the embodiments. Other embodiments include structural, logical, electrical, and process changes. This example merely shows possible changes. If not explicitly required, individual components and functions are optional and the operational sequence may be altered. Some of the embodiments and functions may be included therein and may be replaced with others. The scope of the invention includes the claims and the full scope of those claims, and the requirements of these claims include all equivalents. In such embodiments of the present invention, where there is fact that more than one invention is disclosed, the scope of this application is voluntarily limited to any single invention or inventive concept for convenience only. There is no intent, and is cited here individually or collectively by the term “invention”.

  FIG. 1 is a block diagram of a multi-carrier transmitter according to some embodiments of the present invention. Multicarrier transmitter 100 is part of a wireless communication device and transmits a multicarrier communication signal, such as an orthogonal frequency division multiplexing (OFDM) communication signal, through a multicarrier communication channel.

  In some embodiments, multicarrier transmitter 100 encodes symbols for transmission on a multicarrier communication channel that includes two or more spatial channels and uses two or more transmit antennas 114. In some embodiments, multi-carrier transmitter 100 uses a high-throughput space-frequency block code and does not require the use of convolution or error correction coding, although the scope of the invention is limited in this respect. It will never be done. In some embodiments, the use of high throughput space-frequency block codes by multicarrier transmitter 100 eliminates the need for Viterbi encoding, but the scope of the present invention is not limited in this respect. Absent. In some embodiments, increased throughput and / or increased range is achieved using convolutional codes with similar bit error rate and bandwidth, and through the use of high throughput space-frequency block codes for the system. Achieved.

  In some embodiments, the multi-carrier transmitter 100 encodes the multi-symbol vector 105 by multiplying each symbol vector 105 by a complex field matrix to generate a pre-encoded symbol vector 107. A precoder 106 is included. In some embodiments, multi-carrier transmitter 100 includes a partitioner 108 for grouping pre-encoded symbol vectors 107 into a plurality of groups 109. Each group 109 is two or more pre-encoded symbol vectors 107. In some embodiments, the multi-carrier transmitter 100 may further convert each pre-coded symbol of the pre-coded symbol vector 107 to one of a plurality of sub-carriers and a plurality of spaces of the multi-carrier communication channel. It includes a space-frequency symbol mapper 110 for mapping to one of the channels. In some embodiments, the space-frequency symbol mapper 110 may convert a pre-coded symbol to one of the subcarriers and the space based at least in part on the group of symbols and the position of the symbol within the group. Although mapped to one of the channels, the scope of the present invention is not limited in this respect.

  In some embodiments, the space-frequency symbol mapper 110 may convert a pre-coded symbol to one of the subcarriers and the transmit antenna based at least in part on the group of symbols and the position of the symbol within the group. Although mapped to one of 114, the scope of the present invention is not limited in this respect. In these embodiments, each transmit antenna 114 is associated with one of the spatial channels, but the scope of the invention is not limited in this respect.

  In some embodiments, multi-carrier transmitter 100 further includes a symbol mapper 102 that generates a continuous symbol stream of symbols 103 from an input serial bit stream 101. In some embodiments, mapper 102 is a quadrature amplitude modulation (QAM) symbol mapper that produces a serial symbol stream of QAM symbols, although the scope of the invention is not limited in this respect. In some embodiments, multi-carrier transmitter 100 further includes a serial to parallel converter 104 to generate a plurality of parallel symbol vectors 105 from the serial symbol stream. Each symbol vector 105 has more than one symbol. In some embodiments, parallel symbol vector 105 is a QAM symbol vector.

  In some embodiments, multi-carrier transmitter 100 further includes a Fast Inverse Fourier Transform (IFFT) circuit 112 on the corresponding channel of the spatial channel or the corresponding antenna of transmit antenna 114. A signal 113 for RF transmission is generated from the symbol 111 mapped to the space-frequency provided by 110. In some embodiments, signal 113 is a signal packetized for transmission. In some embodiments, a circuit that adds a cyclic prefix (CP) (guard interval interval) to signal 113 may be included in the signal path after IFFT circuit 112 to help reduce intersymbol interference. The scope of the present invention is not limited to this point. In some embodiments, each transmit antenna 114 corresponds to one of the spatial channels, although the scope of the invention is not limited in this respect.

  In some embodiments, the precoder 106 is a linear square precoder that pre-codes each of the parallel symbol vectors 105 separately and generates a plurality of parallel pre-coded symbol vectors 107. In some embodiments, the complex field matrix (eg, theta) used in the precoder 106 is a square complex field matrix having a substantially row-wise Vandermonde structure, The range is not limited to this point. The Vandermonde matrix relates to a certain matrix that occurs in the least squares of a polynomial suitable for Lagrange's complementary polynomial, and relates to the reconstruction of the statistical distribution from the moment of allocation, but the scope of the present invention is in this respect. There is no limit.

  In some embodiments, the precoder 106 encodes M × G parallel symbol vectors 105 and each of the parallel symbol vectors 105 has M × K symbols. In these embodiments, partitioner 108 groups pre-coded symbol vector 107 into G group 109 of parallel symbol vector 107. Each group 109 has M pre-encoded symbol vectors 107. In these examples, M, G, and K are selected to satisfy the equation Nc = M × K × G, where Nc is related to the number of data subcarriers in the multicarrier channel. M, G and K may be positive integers less than 100. In some embodiments, M corresponds to the number of spatial channels and / or transmit antennas 114, although the scope of the present invention is not limited in this respect. For example, if the multi-carrier communication channel includes 16 data subcarriers and the transmitter uses 4 transmit antennas, M is 4, G is 2 and K is 2. The total number of symbols transmitted will be the number of symbols per symbol vector (ie M × K) times the number of vectors (ie M × G), here 64 symbols. Sixteen symbols (ie, one for each of the 16 data subcarriers) are modulated by each IFFT circuit 112 and transmitted by the corresponding antenna of transmit antenna 114. In an embodiment, K and G are selected based on, among other things, the number of subcarriers and the number of antennas.

  FIG. 2 illustrates a pre-encoded symbol vector according to some embodiments of the present invention. In some embodiments, the symbols of the pre-encoded symbol vector 207 are related to the symbol layer. The pre-encoded symbol vector 207 corresponds to the pre-encoded symbol vector 107 (FIG. 1), but the scope of the present invention is not limited in this respect. Pre-encoded symbol vectors 207 are grouped into two or more groups 209. Pre-encoded symbol vector 207 includes a plurality of pre-encoded symbols 203, respectively. In some embodiments, there are M layers for each of the G groups. In some embodiments, the number of layers M is almost simply the number of transmit antennas. In these embodiments, a space-frequency symbol mapper, such as space-frequency symbol mapper 110 (FIG. 1), pre-codes a pre-coded symbol vector 207 based on the group and layer associated with the symbol. Each encoded symbol 203 is mapped to one of the subcarriers and one of the transmit antennas. In these embodiments, space-frequency symbol mapper 110 (FIG. 1) maps M × K × G symbols to each transmit antenna and / or spatial channel and transmits the antenna for modulation on subcarriers. A plurality of mapped symbols of M × K × G symbols is provided to an IFFT circuit, such as IFFT circuit 112 (FIG. 1) associated with. FIG. 2 includes four layers for each of two groups of pre-encoded symbol vectors 207 (ie, group 109), where each of pre-encoded symbol vectors 207 is eight pre-encoded. Figure 6 illustrates an embodiment of the present invention including a modified symbol 203; In the illustrated embodiment, there are 16 data subcarriers in a multicarrier communication channel, but the scope of the invention is not limited in this respect.

  In some embodiments, the space-frequency symbol mapper 110 (FIG. 1) may use at least some pre-coded symbols 203 of the layer based on the group and position of the pre-coded symbols within the group. Are mapped to subcarriers and transmit antennas in a sequential manner, but the scope of the invention is not limited in this respect. In some embodiments, a first group of first pre-coded symbols is mapped to a first subcarrier and a first transmit antenna, and a first group of second pre-coded symbols is: Maps to second subcarrier and second transmit antenna. A particular mapping is selected to achieve, among other things, increased diversity.

FIG. 3 illustrates space-frequency mapping according to some embodiments of the present invention. Pre-coded symbol 303 is based on one of transmit antenna 114 (FIG. 1) or spatial channel 302 (shown in row) and sub-carrier 304 (column) based on the pre-coded symbol layer and group. 1). In FIG. 3, the pre-encoded symbol 303 corresponds to the pre-encoded symbol 203 (FIG. 2) and is shown as S _ijk , where i is the i th layer, j is the group number, and k is Represents the kth pre-coded symbol. In the illustrated embodiment with 16 data subcarriers, the first group of pre-encoded symbols 303 are mapped to subcarriers 1 to 4 and subcarriers 9 to 12, while the second group of Pre-encoded symbols 303 are mapped to subcarriers 5-8 and subcarriers 13-16.

  In some embodiments, a particular layer of pre-encoded symbols 303 is mapped diagonally in this embodiment. For example, for the first group of symbols, the first layer first symbol 306 is mapped to the first subcarrier and the first transmit antenna, and the first layer second symbol 308 is the second subcarrier and the second transmission. Mapped to the antenna, the third symbol 310 of the first layer is mapped to the third subcarrier and the third transmit antenna, the fourth symbol 312 of the first layer is mapped to the fourth subcarrier and the fourth transmit antenna, The fifth symbol 314 of one layer is mapped to the ninth subcarrier and the first transmission antenna, the sixth symbol 316 of the first layer is mapped to the tenth subcarrier and the second transmission antenna, and the seventh symbol of the first layer 318 is mapped to the eleventh subcarrier and the third transmit antenna, and the eighth symbol 31 of the first layer 31 It is mapped to the 12 sub-carrier and a fourth transmit antenna. This mapping applies to other layers and groups as well, as illustrated in FIG. Another mapping based on layers and groups is performed by the space-frequency symbol mapper 110 (FIG. 1).

  Referring to FIG. 1, in some embodiments, the spatial channel is a correlated channel (eg, non-orthogonal in frequency). In these embodiments, each spatial channel can use subcarriers modulated with symbols of the same frequency. In some embodiments, decorrelation between spatial channels (eg, at least partial orthogonality) is achieved through antenna separation. In some embodiments, the transmit antennas 114 can have a spatial spacing between them that is at least approximately half the wavelength of the transmit frequency. In some embodiments, the space may be selected such that different antennas undergo uncorrelated channel fading. In some embodiments, the high-throughput space-frequency block code used by multi-carrier transceiver 100 may not be sensitive to small antenna placement or separation, and may be robust to antennas that reduce correlation. There is. In some embodiments, antenna separation may be small compared to the transmit wavelength. In some embodiments, decorrelation between spatial channels is achieved through beamforming, but the scope of the invention is not limited in this respect.

  In some embodiments, the multi-carrier communication channel includes a plurality of subcarriers modulated with symbols. In some embodiments, each subcarrier modulated with a symbol has a null point at approximately the center frequency of the other subcarrier to achieve substantial orthogonality between the subcarriers of the multicarrier communication channel. Can do. In some embodiments, the multi-carrier communication channel is an orthogonal frequency division multiplexing (OFDM) communication channel that includes multiple OFDM subcarriers, although the scope of the invention is not limited in this respect.

  In some embodiments, multi-carrier transmitter 100 utilizes two or more spatial diversity transmit antennas 114 to “divide” the channel into two or more spatial channels. In some embodiments, each transmit antenna defines one spatial transmission channel. In other embodiments, multi-carrier transmitter 100 uses beamforming techniques to “split” the channel into spatial channels. In these embodiments, each spatial channel is used to communicate a separate or unrelated data stream on the same subcarrier as the other spatial channels, allowing additional data communication without increasing frequency bandwidth. Allow. The use of a spatial channel takes advantage of the multipath characteristics of the channel. In some embodiments, the spatial channel is a non-orthogonal channel, but the scope of the invention is not limited in this respect.

  In some embodiments, the serial to parallel converter 104 may operate in the signal path preceding the mapper 102. In accordance with some embodiments, the mapper 102 of the multicarrier transmitter 100 symbol modulates the subcarriers according to individual subcarrier modulation assignments. This is sometimes referred to as adaptive bit loading (ABL). Thus, one or more bits are represented by symbols modulated on subcarriers. The modulation assignment for an individual subchannel is based on the channel characteristics or channel conditions for that subcarrier, but the scope of the invention is not limited in this respect. In some embodiments, the subcarrier modulation assignment varies from zero bits per symbol to 10 or more bits per symbol.

  In some embodiments, multi-carrier symbols are viewed as a combination of symbols modulated on individual subcarriers. Due to the variable number of bits per subcarrier modulated with symbols and the variable number of subchannels including multicarrier channels, the number of bits per multicarrier symbol varies greatly.

  In some embodiments, the frequency spectrum for the multi-carrier communication channel includes subcarriers in either the 5 GHz frequency spectrum or the 2.4 GHz frequency spectrum. In these embodiments, the 5 GHz frequency spectrum includes frequencies ranging from approximately 4.9 GHz to 5.9 GHz, and the 2.4 GHz frequency spectrum includes frequencies ranging from approximately 2.3 GHz to 2.5 GHz. However, the scope of the present invention is not limited in this respect, and other frequency spectra may be equally suitable.

  FIG. 4 is a block diagram of a multi-carrier receiver according to some embodiments of the present invention. Multicarrier receiver 400 is part of a wireless communication device and receives a multicarrier communication signal, such as an OFDM communication signal, on a multicarrier communication channel. In some embodiments, multi-carrier receiver 400 may be part of a communication station that further includes a multi-carrier transmitter, such as multi-carrier transmitter 100 (FIG. 1), but other multi-carrier transmissions. The machine may be more appropriate.

  In some embodiments, multi-carrier receiver 400 can receive signals on a multi-carrier communication channel over two or more spatial channels and uses two or more receive antennas 402. In some embodiments, multi-carrier receiver 400 decodes a signal encoded with a high-throughput space-frequency block code and does not require the use of convolutional or error correction decoding, although The range of is not limited to this point. In some embodiments, the use of high throughput space-frequency block codes eliminates the need for Viterbi decoding, but the scope of the invention is not limited in this respect. In some embodiments, increased throughput and / or increased range is achieved through the use of high throughput space-frequency block codes for the system, using convolutional codes with similar bit error rates and bandwidths. The In some embodiments, multi-carrier receiver 400 uses a null process repeatedly to decode signals received over a multi-carrier communication channel encoded with a high-throughput space-frequency block code. Continuously remove interference from the symbol layer.

  In some embodiments, multi-carrier receiver 400 includes a demultiplexer 406 and generates a group of symbol vectors 407 by combining subcarrier frequency components corresponding to received symbol vector 405. Each group of symbol vectors 407 may have symbol components combined from different subcarriers. In some embodiments, symbol vector 407 is generated by demultiplexer 406 in G groups (two groups are shown in FIG. 4). In some embodiments, each of symbol vectors 407 has a length of M × K encoded symbols. In some embodiments, to collect and group information from some of the subcarriers received on all receive antennas 402, demultiplexer 406 reconstructs the row vectors into column vectors, The scope of the invention is not limited to this point.

  Multicarrier receiver 400 further includes a null canceller 408 associated with each group of symbol vectors 407, and based on decoded symbol vector 420, subcarriers for the associated group of symbol vectors. Perform null canceling in units. The null canceller 408 generates a symbol vector 409 with null canceled.

  Multicarrier receiver 400 further includes a decoder 410 associated with each group for decoding null canceled symbol vector 409. In some embodiments, decoder 410 is a sphere decoder that spherically decodes a layer of related groups of symbols, and outputs theta (one decoded layer at a time) to theta and Multiply by a complex field matrix called. In this way, the decoder 410 regenerates a pre-encoded symbol vector 420 (eg, regenerates the current layer) for the null canceller 408 so that all null layers are decoded until all layers are decoded. The canceller 408 cancels the contribution from the current layer symbol vector 407. In some embodiments, the null is performed once for each subcarrier while cancellation is performed for M-1 iterations until all layers are decoded, Is not limited to this point. In some embodiments, the decoder 410 performs maximum likelihood (ML) detection within a sphere or spherical limit, unlike brute force ML detection. In some embodiments, decoder 410 generates a decoded QAM symbol vector 411 for each subcarrier of the multicarrier communication channel.

  In some embodiments, the null canceller 408 may cause the i-th layer to still be subject to interference from the 1st layer to the i-1th layer, and from the i + 1th layer in the symbol vector for a particular subcarrier frequency. The symbols are nulled so that there is substantially no interference up to the Mth layer, but the scope of the present invention is not limited to this point. In some embodiments, the null canceller 408 cancels some elements in the symbol vector 407 after further nulling based on the symbol vector 420. This is done continuously until all layers are decoded. In some embodiments, this is an iterative process. For example, nothing is canceled during the first iteration, and the decoded symbol vector 420 fed back is zero.

  In some embodiments, multicarrier receiver 400 further includes an FFT circuit 404 that demodulates subcarriers of a multicarrier communication channel received via receive antenna 402 and receives symbol vectors associated with each receive antenna. 405 is generated. Received symbol vector 405 (ie, from each antenna 402) includes symbol components from each of the subcarriers of the multicarrier communication channel. In some embodiments, the number of receive antennas 402 is equal to or greater than the number of transmit antennas or spatial channels used to transmit multicarrier communication signals, although the scope of the invention is limited in this respect. It will never be done.

  In some embodiments, multi-carrier receiver 400 further includes a symbol demapper 412 that demaps the decoded symbol vector 111 for each group to generate a plurality of parallel bit sets 413. The symbol demapper 412 may be a QAM demapper, but the scope of the present invention is not limited in this respect. In some embodiments, multi-carrier receiver 400 further includes a parallel to serial converter 414 for generating a serial bit stream 415 from a plurality of parallel bit sets 413.

  In some embodiments, circuitry (not shown) for removing the cyclic prefix (CP) added by the transmitter to reduce intersymbol interference may be included in the signal path before the FFT circuit 404. However, the scope of the present invention is not limited to this point.

  Multi-carrier transmitter 100 (FIG. 1) and / or multi-carrier receiver 400 may be a personal digital assistant (PDA), a laptop or portable computer with wireless communication capabilities, a web tablet, a wireless phone, a wireless On headphones, pagers, instant messaging devices, digital cameras, laptops with access points or other devices, or parts of portable and / or other devices that can receive and / or transmit information wirelessly There may be. In some embodiments, certain communication standards, such as IEEE 802.11 (a), 802.11 (b), 802.11 (g / h), and wireless local area network (WLAN), and In accordance with the Institute of Electrical and Electronics Engineers (IEEE) standards including the 802.11 (n) standard and / or the 802.16 standard for Wireless Urban Area Networks (WMAN) (see FIG. 1). ) Transmits radio frequency (RF) communications, and the multi-carrier receiver 400 receives radio frequency (RF) communications, but the transmitter 100 (FIG. 1) and / or the receiver 400 is further terrestrial digital. -Video broadcasting (DVB-T) broadcasting standard and high-function wireless local area network (HiperLAN) standard Suitable for transmitting and / or receiving communications according to another technique including rating.

  Although some embodiments of the present invention are discussed in an example that embodies 802.11x (eg, 802.11a, 802.11g, 802.11HT, etc.), the claims are not limited thereto. Some embodiments of the present invention are embodied as part of any wireless system that uses a multi-carrier wireless communication channel (eg, Orthogonal Frequency Division Multiplexing (OFDM), Discrete Multitone Modulation (DMT)). ), Etc.), which may be used within a limited range or without limitation, for example, wireless personal area network (WPAN), wireless local area network (WLAN) Used in wireless metropolitan area networks (WMAN), wireless wide area networks (WWAN), cellular networks, third generation (3G) networks, fourth generation (4G) networks, universal mobile phone systems (UMTS) and similar communication systems Is done.

  In some embodiments, each transmit antenna 114 (FIG. 1) and each receive antenna 402 includes a directional or omnidirectional antenna, such as a dipole antenna, a monopole antenna, a loop antenna, a microstrip antenna. Or other types of antennas suitable for receiving and / or transmitting RF signals.

  In some embodiments, multi-carrier transmitter 100 (FIG. 1) and / or multi-carrier receiver 400 are part of a single multi-carrier communication station. Although multi-carrier transmitter 100 (FIG. 1) and / or multi-carrier receiver 400 is illustrated as part of one or more wireless communication devices, multi-carrier transmitter 100 (FIG. 1) and / or multi-carrier Receiver 400 may be part of any wireless or wired communication device that includes a general purpose processing or computing system. In some embodiments, multi-carrier transmitter 100 (FIG. 1) and / or multi-carrier receiver 400 may be part of a battery-powered device. In some embodiments, if transmitter 100 (FIG. 1) and receiver 400 are part of a communication station, the transmit and receive antennas may be shared, but the scope of the invention is limited in this respect. Never happen.

  Multi-carrier transmitter 100 (FIG. 1) and / or multi-carrier receiver 400 is illustrated as comprising several individual functional elements, but one or more functional elements may be combined, It may also be implemented in combination with processing elements including a digital signal processor (DSP) and / or software-oriented elements such as other hardware elements. For example, the illustrated elements include one or more microprocessors, DSPs, application specific integrated circuits (ASICs), and combinations of various hardware and logic circuits to perform at least the functions described herein.

  Unless specifically stated otherwise, processing, computing, computing, and judging, displaying or like terms may refer to the operation or process of one or more processing or computing systems or similar devices. , It also represents data represented as physical quantities in the processing system registers and memory (eg, electronics), and other data represented in the processing system registers or memory or other information stored, transmitted, physical quantities in the display device as well Manipulate and convert to data. Further, as used herein, a computing (computing) device includes one or more processing elements coupled to computer readable memory that is volatile or non-volatile memory, or a combination thereof.

  FIG. 5 is a flowchart illustrating a procedure for transmitting space-frequency symbols according to some embodiments of the present invention. Spatial-frequency symbol transmission procedure 500 is performed by a multicarrier transmitter, such as multicarrier transmitter 100 (FIG. 1), although other multicarrier transmitters are also suitable. In some embodiments, procedure 500 encodes symbols for transmission on a multi-carrier communication channel that includes more than one spatial channel and uses more than one transmit antenna.

  Act 502 includes generating a serial symbol stream from an input serial bit stream. In some embodiments, operation 502 is performed by a symbol mapper, such as mapper 102 (FIG. 1).

  Act 504 includes generating a plurality of parallel symbol vectors from the serial symbol stream. Each symbol vector has more than one symbol. In some embodiments, operation 504 is performed by a series-parallel converter, such as series-parallel converter 104 (FIG. 1).

  Act 506 includes multiplying each symbol vector by a complex field matrix to encode a plurality of symbol vectors to generate a pre-encoded symbol vector. In some embodiments, operation 506 encodes the symbol vector with a linear square precoder that pre-encodes each of the plurality of parallel symbol vectors separately to generate a plurality of pre-encoded parallel symbol vectors. Including doing. In some embodiments, the complex field matrix is a square complex field matrix with a substantially row-wise Vandermonde structure, although the scope of the invention is not limited in this respect. In some embodiments, operation 506 is performed by a precoder, such as precoder 106 (FIG. 1).

  Act 508 includes grouping the pre-encoded symbol vectors into a plurality of groups. Each group has two or more pre-encoded symbol vectors. In some embodiments, operation 508 is performed by a partitioner, such as partitioner 108 (FIG. 1).

  Operation 510 multiplies a pre-coded symbol of a pre-coded symbol vector based at least in part on a group of pre-coded symbols and a position within the group of pre-coded symbols. Mapping to one of a plurality of subcarriers and one of a plurality of spatial channels of a carrier communication channel. In some embodiments, operation 510 maps a pre-encoded symbol of a pre-encoded symbol vector to one of the subcarriers and one of the multiple transmit antennas of the multicarrier communication channel. including. Each transmit antenna corresponds to one of the spatial channels, but the scope of the present invention is not limited in this respect. In some embodiments, operation 510 is performed by a space-frequency symbol mapper, such as space-frequency symbol mapper 110 (FIG. 1).

  Act 512 includes performing a Fast Inverse Fourier Transform (IFFT) to modulate the modulated signal for RF transmission on the corresponding one of the spatial channels from the space-frequency mapped symbols generated in act 510. Generate.

  FIG. 6 is a flowchart illustrating symbol reception and decoding procedures according to some embodiments of the present invention. Symbol reception and decoding procedure 600 is performed by a multi-carrier receiver, such as multi-carrier receiver 400 (FIG. 4), although other multi-carrier receivers may be more appropriate. Procedure 600 is for decoding a signal transmitted by a multicarrier transmitter, such as multicarrier transmitter 100 (FIG. 1), or for decoding a multicarrier signal generated by procedure 500 (FIG. 5). Although practiced, the scope of the present invention is not limited in this respect.

  Act 604 includes demodulating the subcarriers of the multicarrier communication signal received on the plurality of receive antennas to generate a receive symbol vector associated with each receive antenna. In some embodiments, the received symbol vector includes symbol components from each of the subcarriers of the multicarrier communication channel. In some embodiments, operation 604 is performed by an FFT circuit, such as FFT circuit 404 (FIG. 4).

  Act 606 includes generating a group of symbol vectors by combining corresponding subcarrier frequency components of the received symbol vector. In some embodiments, operation 606 includes reconstructing and / or demultiplexing the symbol vector. In some embodiments, each group of symbol vectors may include symbol components combined from different subcarriers. In some embodiments, operation 606 is performed by a demultiplexer, such as demultiplexer 406 (FIG. 4).

  Act 608 includes null-cancelling the associated group of symbol vectors on a subcarrier basis based on the decoded symbol vector to generate a null-cancelled symbol vector. In some embodiments, operation 608 iteratively cancels interference from symbol vectors in successive layers. In some embodiments, the null canceller disables interference from the symbol vector 407 (FIG. 4) so that the i th layer still interferes with the first through i−1 layers, Although there is no substantial interference from the (i + 1) th layer to the Mth layer, the scope of the present invention is not limited to this point. In some embodiments, operation 608 is performed by a null canceller, such as null canceller 408 (FIG. 4).

  Act 610 includes decoding a layer of symbols of the associated group by multiplying the decoded output 1 layer at a time by a complex field matrix and regenerating a symbol vector for null canceling. To do. In some embodiments, operation 610 is performed by a decoder, such as decoder 410 (FIG. 4). In some embodiments, operation 610 includes spherical decoding to generate a decoded QAM symbol vector for each subcarrier of the multicarrier communication channel, although the scope of the invention is limited in this respect. It will never be done.

  Act 612 includes inverse mapping the decoded symbol vectors for each group to generate a plurality of parallel bit sets. Operation 612 is performed by a symbol inverse mapper, such as inverse mapper 412 (FIG. 4).

  Act 614 includes generating a serial bit stream from a plurality of parallel bit sets. In some embodiments, operation 614 is performed by a parallel to serial converter, such as parallel to serial converter 414 (FIG. 4).

  Although the individual operations of procedures 500 and 600 are illustrated and described as individual operations, one or more individual operations may be performed simultaneously, and the operations are performed in the order shown. do not need.

  Embodiments of the present invention are implemented in hardware, firmware and / or software. Embodiments of the invention are implemented as instructions stored on a machine-readable medium, which are read and executed by at least one processor to perform the operations described herein. A machine-readable medium includes any mechanism for storing or transmitting information in a form readable by a machine (eg, a computer). For example, machine readable media include read only memory (ROM), random access memory (RAM), magnetic disk storage media, optical storage media, flash memory devices, electrical, optical, acoustic, Or other forms of propagated signals (eg, carrier waves, infrared signals, digital signals, etc.) and other forms.

  This summary requires a summary that can confirm the nature and gist of the technical disclosure. F. R. Provided to comply with Section 1.72 (b). It is submitted with the understanding that it will not be used to limit or interpret the scope or meaning of the claims.

  In the foregoing detailed description, various features are sometimes grouped together in a single embodiment for the purpose of simplifying the specification. This method in the specification should not be construed as reflecting an invention in which the subject embodiment requires more features than are expressly recited in each claim. Rather, as the following claims indicate, the invention is less than all the features of a single disclosed embodiment. Thus, the following claims are hereby incorporated into this detailed description, with each claim standing on its own as a separate preferred embodiment.

FIG. 2 is a block diagram of a multi-carrier transmitter according to some embodiments of the present invention. Fig. 4 illustrates a predetermined encoded symbol vector according to some embodiments of the present invention. Fig. 4 illustrates a space-frequency mapping according to some embodiments of the present invention. FIG. 2 is a block diagram of a multi-carrier receiver according to some embodiments of the invention. FIG. 4 is a flowchart illustrating a procedure of transmitting space-frequency symbols according to some embodiments of the present invention. FIG. 6 is a flowchart illustrating symbol reception and decoding procedures according to some embodiments of the present invention.

Claims (42)

A precoder that encodes a plurality of symbol vectors by multiplying each of the symbol vectors by a complex field matrix to generate a pre-encoded symbol vector;
A partitioner for grouping the pre-encoded symbol vectors into a plurality of groups, each group having two or more pre-encoded symbol vectors;
A pre-encoded symbol of the pre-encoded symbol vector is at least partially based on the group of pre-encoded symbols and the position of the pre-encoded symbol within the group. A spatial-frequency symbol mapper that maps to one of a plurality of subcarriers of a carrier communication channel and one of a plurality of spatial channels;
A multi-carrier transmitter comprising: A symbol mapper that generates a serial symbol stream from an input serial bit stream;
A serial-parallel converter for generating a plurality of parallel symbol vectors from the serial symbol stream, wherein the symbol vector comprises two or more symbols;
The transmitter of claim 1, further comprising:   A fast inverse Fourier transform (IFFT) circuit that generates a signal for radio frequency (RF) transmission on a corresponding channel of the spatial channel from the space-frequency mapped symbols provided by the space-frequency symbol mapper The transmitter of claim 2, further comprising:   The precoder is a linear square precoder that pre-codes each of the plurality of parallel symbol vectors separately and generates a plurality of parallel pre-coded symbol vectors. Transmitter.   5. The transmitter according to claim 4, wherein the complex field matrix is a square complex field matrix having a substantially Verndelmond structure in a row direction.   The transmitter of claim 1, further comprising a plurality of transmit antennas, each transmit antenna corresponding to one of the spatial channels. The precoder encodes M × G parallel symbol vectors, each parallel symbol vector having M × K symbols;
The partitioner groups the pre-encoded symbol vectors into groups of G parallel symbol vectors, each group having M pre-encoded symbol vectors;
Here, M, G and K are positive integers,
M × K × G is equal to the number of data subcarriers of the multicarrier communication channel,
M is equal to the number of transmit antennas,
The transmitter according to claim 6. The symbols of the pre-encoded symbol vector are associated with a layer of symbols, the number of layers being M for each group;
The space-frequency symbol mapper determines each pre-coded symbol of the pre-coded symbol vector based on the group and the layer associated with the symbol and the sub-carrier and the layer. Map to one of the transmit antennas,
The space-frequency symbol mapper maps M × K × G symbols to each transmit antenna and maps a mapped symbol of a plurality of M × K × G symbols for modulation on the subcarrier. Providing an IFFT circuit associated with the transmit antenna;
The transmitter according to claim 7.   The space-frequency symbol mapper maps at least some symbols of the layer to the subcarriers and the transmit antennas in a sequential manner based on the group of symbols and the position within the group. The transmitter according to claim 7. The multi-carrier communication channel includes a plurality of spatial channels, each spatial channel associated with one of a plurality of transmit antennas;
Each spatial channel uses subcarriers with the same frequency as the other spatial channels,
The transmitting antennas have a distance of at least approximately a half wavelength of the transmitting frequency between them,
The transmitter according to claim 1. The multicarrier communication channel includes subcarriers modulated with a plurality of symbols;
The subcarriers modulated in each symbol have a null point at substantially the center frequency of the other subcarriers to achieve substantial orthogonality between the subcarriers of the multicarrier communication channel.
The transmitter according to claim 1. The transmitter is a part of a multicarrier communication station including the multicarrier transmitter and a multicarrier receiver, and the multicarrier receiver
A demultiplexer that generates a group of symbol vectors by combining the corresponding subcarrier frequency components of the received symbol vector;
A null canceller associated with each group of symbol vectors for performing null cancellation on a per subcarrier basis for the associated group of symbol vectors based on the decoded symbol vector, the null canceller The canceller generates a null point canceled symbol vector, and a null canceller,
Associated with each group, decoding a layer of symbols of the associated group and multiplying the output of the decoder by a complex field matrix one layer at a time to regenerate the symbol vector for the null canceller The decoder
The transmitter according to claim 1, comprising: A demultiplexer that generates a group of symbol vectors by combining the corresponding subcarrier frequency components of the received symbol vector;
A null canceller associated with each group of symbol vectors for performing null cancellation on a subcarrier basis for the associated group of symbol vectors based on the decoded symbol vector, comprising: The canceller generates a null point canceled symbol vector, and a null canceller,
A decoder associated with each group that decodes a layer of symbols of the associated group and multiplies the decoder output by a complex field matrix one layer at a time to regenerate a symbol vector for the null canceller When,
A multi-carrier receiver comprising:   The receiver according to claim 13, wherein the null canceller repetitively cancels interference from the symbol vectors in successive layers. Each group of symbol vectors generated by the demultiplexer includes components of symbols combined from different subcarriers;
The decoder is a sphere decoder and generates a decoded quadrature amplitude modulation symbol vector for each subcarrier of the multicarrier communication channel;
The receiver according to claim 13. An FFT circuit that demodulates reception subcarriers of the multicarrier communication signal received on a plurality of reception antennas and generates the reception symbol vectors associated with each reception antenna, wherein the reception symbol vectors are An FFT circuit including components of symbols from a plurality of subcarriers of a carrier communication channel;
An inverse mapper that inverse maps the decoded symbol vector for each group to generate a plurality of parallel bit sets;
A parallel-serial converter that generates a serial bit stream from the plurality of parallel bit sets;
14. The receiver of claim 13, further comprising: The receiver is a part of a multicarrier communication station including the multicarrier transmitter and a multicarrier receiver, and the multicarrier transmitter is
A precoder for encoding a plurality of symbol vectors by multiplying each of the symbol vectors by a complex field matrix and generating a pre-encoded symbol vector;
A partitioner for grouping the pre-encoded symbol vectors into a plurality of groups, each group having two or more pre-encoded symbol vectors;
A pre-encoded symbol of the pre-encoded symbol vector is at least partially based on the group of pre-encoded symbols and the position of the pre-encoded symbol within the group. A spatial-frequency symbol mapper that maps to one of a plurality of subcarriers of a carrier communication channel and one of a plurality of spatial channels;
14. The receiver of claim 13, further comprising: Multiple antennas,
A multi-carrier transmitter that encodes symbols with space-frequency block codes for transmission on a multi-carrier communication channel;
The space-frequency block code includes pre-encoded symbols mapped to the plurality of transmit antennas and subcarriers of the multicarrier communication channel;
A communication station characterized by this. The multi-carrier transmitter is
A precoder for encoding a plurality of symbol vectors by multiplying each of the symbol vectors by a complex field matrix and generating a pre-encoded symbol vector;
A partitioner for grouping the pre-encoded symbol vectors into a plurality of groups, each group having two or more pre-encoded symbol vectors;
A pre-encoded symbol of the pre-encoded symbol vector is at least partially based on the group of pre-encoded symbols and the position of the pre-encoded symbol within the group. A spatial-frequency symbol mapper that maps to one of a plurality of subcarriers of a carrier communication channel and one of a plurality of spatial channels;
The communication station according to claim 18, further comprising:   A multi-carrier that continuously decodes interference from a layer of symbols by decoding a signal received on the multi-carrier communication channel and encoded with the space-frequency block code using a repeating null process The communication station according to claim 18, further comprising a receiver. The multi-carrier receiver
A demultiplexer that generates a group of symbol vectors by combining the corresponding subcarrier frequency components of the received symbol vector;
A null canceller associated with each group of symbol vectors for performing null cancellation on a subcarrier basis for the associated group of symbol vectors based on the decoded symbol vector, The canceller generates a null-point canceled symbol vector, and a null canceller
Associated with each group, decoding a layer of symbols of the associated group and multiplying the output of the decoder by a complex field matrix one layer at a time to regenerate the symbol vector for the null canceller The decoder
The communication station according to claim 20, further comprising: Encoding a plurality of symbol vectors by multiplying each of the symbol vectors by a complex field matrix to generate a pre-encoded symbol vector;
Grouping the pre-encoded symbol vectors into a plurality of groups, each group having two or more pre-encoded symbol vectors;
A pre-encoded symbol of the pre-encoded symbol vector is at least partially based on the group of pre-encoded symbols and the position of the pre-encoded symbol within the group. Mapping to one of a plurality of subcarriers and one of a plurality of spatial channels of a carrier communication channel;
A method for transmitting via a multi-carrier communication channel. Generating a serial symbol stream from an input serial bit stream;
Generating a plurality of parallel symbol vectors from the serial symbol stream, each of the symbol vectors having two or more symbols;
The method of claim 22 further comprising:   Fast inverse Fourier generating a signal for radio frequency (RF) transmission on the corresponding channel of the spatial channel from the space-frequency mapped symbols generated by mapping the pre-coded symbols 24. The method of claim 23, further comprising performing a transformation (IFFT).   23. The encoding step of claim 22, wherein each of the plurality of parallel symbol vectors is separately pre-encoded to generate a plurality of parallel pre-encoded symbol vectors. the method of.   26. The method of claim 25, wherein the complex field matrix is a square complex field matrix having a substantially row-wise Vandermonde structure. The mapping step maps the pre-encoded symbol of the pre-encoded symbol vector to one of the subcarriers and one of a plurality of transmit antennas of the multicarrier communication channel. Each transmit antenna corresponds to one of the spatial channels,
23. The method of claim 22, wherein: The encoding step encodes M × G parallel symbol vectors, each parallel symbol vector having M × K symbols;
Said grouping comprises grouping said pre-encoded symbol vectors into groups of G parallel symbol vectors, each group comprising M said pre-encoded symbol vectors;
Here, M, G and K are positive integers,
M × K × G is equal to the number of data subcarriers of the multicarrier communication channel,
M is equal to the number of transmit antennas,
28. The method of claim 27. The symbols of the pre-encoded symbol vector are associated with a layer of symbols, the number of layers being M for each group;
The mapping step comprises: assigning each precoded symbol of the precoded symbol vector to one of the subcarriers and the transmit antenna based on the group and the layer associated with the symbol. Map to one,
The mapping step maps M × K × G symbols to each transmit antenna and provides symbols mapped to a collection of M × K × G symbols for modulation on the subcarrier. ,
29. The method of claim 28.   The step of mapping includes the step of mapping at least some symbols of the layer to the subcarriers and the transmit antennas in a sequential manner based on the group of symbols and the position within the group. 30. The method of claim 28. The multi-carrier communication channel includes a plurality of spatial channels, each spatial channel associated with one of a plurality of transmit antennas;
Each spatial channel uses subcarriers with the same frequency as the other spatial channels,
The transmitting antennas have a distance of at least approximately a half wavelength of the transmitting frequency between them,
23. The method of claim 22, wherein: The multicarrier communication channel includes subcarriers modulated with a plurality of symbols;
The subcarriers modulated into each symbol have a null point at substantially the center frequency of the other subcarriers to achieve substantial orthogonality between the subcarriers of the multicarrier communication channel.
23. The method of claim 22, wherein: Generating a group of symbol vectors by combining the corresponding subcarrier frequency components of the received symbol vector; and
Performing null cancellation per subcarrier for the associated group of symbol vectors based on the decoded symbol vector to generate a null-cancelled symbol vector;
Decoding the layer of symbols of the associated group by multiplying the encoded output by a layer once with a complex field matrix, and regenerating the symbol vector for null cancellation;
A method for receiving via a multi-carrier communication channel.   34. The method of claim 33, wherein performing null cancellation includes iteratively canceling interference from the symbol vectors in successive layers. Each group of symbol vectors generated by the demultiplexer includes symbol components combined from different subcarriers;
The encoding step includes spherical encoding to generate a decoded quadrature amplitude modulation symbol vector for each subcarrier of the multi-carrier communication channel.
34. The method of claim 33. Demodulating received subcarriers of the multicarrier communication signal received on a plurality of receive antennas to generate the received symbol vectors associated with each receive antenna, wherein the received symbol vectors are the multicarriers Including components of symbols from a plurality of subcarriers of a communication channel; and
Back-mapping the vector of decoded symbols for each group to generate a plurality of parallel bit sets;
Generating a serial bit stream from the plurality of parallel bit sets;
36. The method of claim 35, further comprising: One or more substantially omnidirectional transmit antennas;
A multi-carrier transmitter coupled to the transmit antenna, the multi-carrier transmitter comprising:
A precoder for encoding a plurality of symbol vectors by multiplying each of the symbol vectors by a complex field matrix and generating a pre-encoded symbol vector;
A partitioner for grouping the pre-encoded symbol vectors into a plurality of groups, each group having two or more pre-encoded symbol vectors;
A pre-encoded symbol of the pre-encoded symbol vector is at least partially based on the group of pre-encoded symbols and the position of the pre-encoded symbol within the group. A spatial-frequency symbol mapper that maps to one of a plurality of subcarriers of a carrier communication channel and one of a plurality of spatial channels;
A system characterized by including. A symbol mapper that generates a serial symbol stream from an input serial bit stream;
A serial-parallel converter for generating a plurality of parallel symbol vectors from the serial symbol stream, wherein each of the serial vectors has two or more symbols;
38. The system of claim 37, further comprising:   A fast inverse Fourier transform (IFFT) circuit that generates a signal for radio frequency (RF) transmission on a corresponding channel of the spatial channel from the space-frequency mapped symbols provided by the space-frequency symbol mapper 40. The system of claim 38, further comprising: In a machine readable medium providing instructions, when the instructions are executed by one or more processors, the processor comprises:
Encoding a plurality of symbol vectors by multiplying each of the symbol vectors by a complex field matrix to generate a pre-encoded symbol vector;
Grouping the pre-encoded symbol vectors into a plurality of groups, each group having two or more pre-encoded symbol vectors;
A pre-encoded symbol of the pre-encoded symbol vector is at least partially based on the group of pre-encoded symbols and the position of the pre-encoded symbol within the group. Map to one of a plurality of subcarriers of a carrier communication channel and one of a plurality of spatial channels;
A machine-readable medium, wherein the operation is performed. In a machine readable medium providing instructions, when the instructions are executed by one or more processors, the processor comprises:
Generate a serial symbol stream from an input serial bit stream;
Generating a plurality of parallel symbol vectors from the serial symbol stream, each of the symbol vectors having two or more symbols;
41. The machine readable medium of claim 40, wherein the operation is performed.   In a machine readable medium that provides instructions, when the instructions are executed by one or more processors, the processor maps to a space-frequency generated by mapping the pre-encoded symbols. 42. Machine-readable according to claim 41, wherein a fast inverse Fourier transform (IFFT) is performed from the generated symbols to generate a signal for radio frequency (RF) transmission on a corresponding channel of the spatial channel Medium.

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