KR101077749B1 - Quasi-orthogonal space-time block encoder, decoder and methods for space-time encoding and decoding orthogonal frequency division multiplexed signals in a multiple-input multiple-output system - Google Patents

Abstract

Embodiments of a quasi-orthogonal space-time encoder, decoder and method for space-time encoding and decoding of orthogonal frequency division multiplexing (OFDM) signals in a multiple input multiple output (MIMO) system are described herein generally. Other embodiments may be described and claimed. In some embodiments, a method of decoding received multicarrier signals includes deriving objective functions from a received signal matrix, minimizing objective functions to produce decoded hard bits, and decoded soft bits. Solving the simultaneous linear equations of the objective functions to produce.

MIMO, OFDM, Objective Function, Quasi-Ortho, Hard Bit, Soft Bit

Description

QUASI-ORTHOGONAL SPACE-TIME BLOCK ENCODER, DECODER AND METHODS FOR SPACE-TIME ENCODING AND DECODING ORTHOGONAL FREQUENCY DIVISION MULTIPLEXED SIGNALS IN A MULTIPLE-INPUT MULTIPLE-OUTPUT SYSTEM}

The present invention relates to wireless communication systems. Some embodiments relate to transmitting and receiving multicarrier signals using a plurality of antennas. Some embodiments relate to multiple-input, multiple-output (MIMO) orthogonal frequency division multiplexed (OFDM) systems.

Some wireless communication systems use multiple transmit antennas and / or multiple receive antennas to increase the amount of data that can be transmitted. In some MIMO systems using multicarrier signals, such as OFDM, each transmit antenna can be configured to transmit a separately encoded information stream on the same set of subcarriers. Decoding individual subcarriers at the receiver becomes increasingly difficult when three or more transmit antennas are used, especially for high coding rates.

Thus, there is a general need for encoders, decoders and methods for encoding and decoding in reduced complexity multicarrier systems.

1 is a functional block diagram of a multicarrier transmitter in accordance with some embodiments of the present invention.

2 is a functional diagram of a space-time encoder in accordance with some embodiments of the present invention.

3 is a functional block diagram of a multicarrier receiver in accordance with some embodiments of the present invention.

4 is a functional diagram of a space-time decoder in accordance with some embodiments of the present invention.

In the following description and drawings it will be described sufficiently that those skilled in the art to practice the specific embodiments of the present invention. Other embodiments may include structural, logical, electrical, process, and other changes. Portions and features of some embodiments may be included in or substituted for portions and features of other embodiments. Embodiments of the invention set forth in the claims include all possible equivalents of those claims. The embodiments of the present invention are not intended to limit the scope of the present application to any one invention or novel concept when two or more inventions are in fact disclosed, but merely for convenience, individually or collectively, The term "invention" may be referred to.

1 is a functional block diagram of a multicarrier transmitter in accordance with some embodiments of the present invention. The multicarrier transmitter 100 transmits the multicarrier signals generated from the input bit stream 101 using the plurality of transmit antennas 114. In some embodiments, multicarrier transmitter 100 may be part of a multiple input, multiple output (MIMO) communication system, and each of transmit antennas 114 may transmit different information symbols. The multicarrier transmitter 100 generates constellation symbols from the error correction encoder 102, the encoded bit stream 103, and encodes the space-time encoded constellation for encoding the input bit stream 101. It may include a space-time encoder 108 for providing inversion symbols to the inverse Fourier transform (IFT) circuit 110. Constellation symbols can be viewed as frequency-domain symbols. IFT circuit 110 may perform an inverse discrete Fourier transform to convert the blocks of these frequency-domain signals into time-domain. Each of these transformed blocks may be referred to as a multicarrier symbol or an OFDM symbol.

The multicarrier transmitter 100 also generates RF signals from the digital time-domain baseband signals provided by the IFT circuit 110 for radio-frequency for transmission by the corresponding one of the transmit antennas 114. (RF) circuit 112 may be included. Multicarrier transmitter 100 may also include other functional elements not shown in FIG. 1 to facilitate understanding.

According to some embodiments, the space-time encoder 108 space-time encodes the multicarrier signals by generating a constellation set from the initial bit stream 103 and corresponds to the number of transmit antennas 114. The bits of the constellation set are mapped to form a plurality of complex symbols. The space-time encoder 108 may also linearly transform the symbols of the constellation set using the selected linear transformation matrix to generate linearly transformed symbols. Space-time encoder 108 may also form complex symbols corresponding to the number of transmit antennas 114 from the linearly transformed symbols. The space-time encoder 108 may also form code matrices, for example Alamouti code matrices, from the complex symbols and transmit a multicarrier signal for transmission by the transmit antennas 114. A quasi-orthogonal space-time matrix can be generated from the code matrices for use in the generation of. These examples are discussed in more detail below.

In some embodiments, the sequence of symbols represented by one dimension (eg, row) of the quasi-orthogonal space-time matrix includes multicarrier signals, by transmit antennas 114. It may be further processed for subsequent transmission on the plurality of subcarriers. These embodiments are also discussed in more detail below.

In some embodiments, for each transmit antenna 114, an inverse Fourier transform is performed by the IFT circuit 110 for each symbol in one dimension (eg, row) of the quasi-orthogonal space-time matrix. Can be performed to generate a time-domain waveform. For each transmit antenna 114, the time-domain waveform may be upconverted by the RF circuit 112 for transmission by the associated transmit antenna of the transmit antennas 114. Each transmit antenna 114 may simultaneously transmit information represented by groups of symbols of one dimension (eg, row) of the quasi-orthogonal space-time matrix. These embodiments are also discussed in more detail below.

In some embodiments, the code matrices generated from the linearly transformed symbols can include aramidity code matrices, and the quasi-orthogonal space-time matrix can include one of the aramidity code matrices. In some embodiments, the constellation set may comprise a quadrature amplitude modulation (QAM) constellation set generated from the bit stream 103. These embodiments are also discussed in more detail below.

Although some embodiments of the present invention are described using four transmit antennas 114, the scope of the present invention is not limited in this respect, since other numbers of transmit antennas may also be used. The transmit antennas 114 are, for example, dipole antennas, monopole antennas, patch antennas, loop antennas, microstrip antennas. Or directional or omnidirectional antennas, including other types of antennas suitable for transmission of RF signals. In some MIMO embodiments, instead of two or more antennas, one antenna with multiple apertures may be used. In these embodiments, each aperture may be considered a separate antenna. In some embodiments, each antenna may be effectively separated to take advantage of different channel characteristics and spatial diversity that may occur between each transmit antenna 114 and another wireless communication device. In some embodiments, the transmit antennas 114 may be separated up to one tenth or more of the wavelength.

2 is a functional diagram of a space-time encoder according to some embodiments of the invention. Space-time encoder 200 may be suitable for use as space-time encoder 108 (FIG. 1), but other space-time encoder configurations may also be suitable.

In these embodiments, the space-time encoder 200 includes a constellation set generator 210 for generating a constellation set (S) 211 from the bit stream 103, and a constellation set ( And a symbol mapper 220 for mapping the bits of 211 into a plurality of complex symbols z _i 221. Complex symbols z _i may be represented by r _i + js _i . The number of complex symbols 221 may correspond to the number of transmit antennas, eg, transmit antennas 114 (FIG. 1). In these embodiments, the space-time encoder 200 also linearly transforms the complex symbols 221 using a selected transformation matrix 261 (eg, U ₁ , U ₂ or U ₃ ) to perform a linear transformation. Linear conversion circuit 230 for generating the converted symbols p _i , q _i 231. Space-time encoder 200 may also include a complex symbol generator 240 for forming complex symbols 241 for the respective transmit antennas from linearly transformed symbols 231. In these embodiments, the space-time encoder 200 also includes a code matrix generator 242 for forming code matrices (A, B) 243 from complex symbols 241, and code matrices ( From 243, a quasi-orthogonal space-time matrix generator 244 for generating a quasi-orthogonal space-time matrix (Q) 246 for use in generating multicarrier signals for transmission at transmit antennas.

In some embodiments, space-time encoder 200 may also include one dimension (eg, row) of quasi-orthogonal space-time matrix 246 for further processing and subsequent transmission by transmit antennas. May include a selection circuit 250 for selecting a sequence of symbols represented by. Each transmit antenna may concurrently transmit information represented by groups of symbols in the dimension (eg, row) of quasi-orthogonal space-time matrix 246.

In some embodiments, when four transmit antennas are used, each transmit antenna may transmit OFDM signals on a plurality of subcarriers. In some embodiments, the number of subcarriers can be 52, but can range from as little as 10 to more than 100 or more. Each OFDM symbol includes a plurality of subcarriers. In some embodiments with four transmit antennas, for each subcarrier using optimally transformed 4x4 quasi-orthogonal space-time block codes of rate 1 (ie, four independent information symbols, one per antenna) The four OFDM symbols can be encoded together by the space-time encoder 200 and decoded together by a multicarrier receiver, eg, the multicarrier receiver 300 (FIG. 3). In these embodiments, one information symbol is transmitted simultaneously by each transmit antenna.

In these embodiments, the constellation set generator 210 may generate the constellation set 211 from the bit stream 103. In these embodiments, the constellation set 211 may represent a QAM signal constellation with a total of N1 × N2 points. The constellation set 211 can be expressed as follows:

In this equation, d represents the distance of the closed points in each direction and can be measured based on the average transmit power used by the multicarrier transmitter 100 (FIG. 1). N1 and N2 may include positive integers such as 2, 4, 8, etc., and may vary depending on the modulation level (ie, number of bits per symbol) and / or transmission rate.

In some embodiments using four transmit antennas, symbol mapper 220 may map the binary information bits in the constellation set S to four complex symbols z _i . In these embodiments,

이며, 여기에서

이다.

, Where

to be.

In these equations, r _i and s _i represent the real part and the imaginary part of complex symbols z _i . In the case of four transmit antennas, the index i is in the range of 1 to 4 corresponding to the number of transmit antennas.

As described below, these information symbols (ie, r _i and s _i ) are 4x4 quasi-orthogonal space-time with one dimension (e.g., row) mapped to each of the four transmit antennas. Encoded sequentially in a block code matrix. Another dimension (ie, column) may represent symbols in the frequency domain.

In these embodiments with four transmit antennas, the linear transformation circuit 230 applies the linear transformation matrix 261, which may be a 4 × 4 real matrix, discussed in more detail below, to the symbol mapper 220. Eight real symbols generated by (i.e. r _i and s _i for i = 1,2,3,4) and p by another eight real symbols (ie i = 1,2,3,4 _i and q _i ). An example of a linear transformation performed by the linear transformation circuit 230 is represented by the following equation:

In these equations, T represents a transpose operation and U represents a selected linear transformation matrix 261. The generation of the linear transformation matrix 261 is discussed below.

In some embodiments, when four transmit antennas are used, complex symbol generator 240 may form another set of four complex symbols 241, which may be represented as follows:

for i = 1,2,3,4

From these formed four complex symbols, code matrix generator 242 may form two 2x2 code matrices 243, e.g., the Aramouti code matrices illustrated below:

In some embodiments using four transmit antennas, quasi-orthogonal space-time matrix generator 244 generates a 4x4 quasi-orthogonal space-time matrix (Q) 246 from two Aramouti code matrices. can do. Quasi-orthogonal space-time matrix 246 can be illustrated as follows:

In these embodiments, each row of quasi-orthogonal space-time matrix 246 may be used to generate time-domain signals for one of the transmit antennas, although the scope of the present invention is limited in this regard. It doesn't happen. In some alternative embodiments, each column of quasi-orthogonal space-time matrix 246 may be used to generate time-domain signals for one of the transmit antennas. In some embodiments, the selection circuit 250 is a space-time encoding represented by one dimension (eg, row) of the quasi-orthogonal space-time matrix 246 for further processing before transmission. It is possible to select a sequence of symbols.

The linear transformation matrix 261 used by the linear transformation circuit 230 described above may be defined as a 4x4 real matrix U. In some embodiments, linear transformation matrix generator 260 may generate one or more linear transformation matrices based on the following equations:

, 및

, And

In these equations, N1 and N2 correspond to integers used by constellation set generator 210. Diagonalization of the symmetry matrix Σ

이고, ε₁ 및 ε₂는 ∑의 고유값들이며, V는 2×2 직교 행렬이다.Can be expressed as

Ε ₁ and ε ₂ are the eigenvalues of Σ, and V is a 2 × 2 orthogonal matrix.

In these embodiments,

이다.

to be.

The linear transformation matrix U can be selected from one of the following three matrices U _i (i = 1,2,3):

Here, P2 and P3 are permutation matrices that can be defined as follows:

In these embodiments, using one of the linear transformation matrices U ₁ , U _2, and U ₃ , increase and / or increase of quasi-orthogonal space-time block codes using minimal maximum-likelihood (ML) decoding. It may help to achieve an optimal diversity product (ie, increased determinant distance and / or coding benefit / gain).

In some embodiments, when the constellation set 211 is a square QAM matrix (ie, N1 = N2), the linear transformation matrix U ₁ becomes orthogonal and takes the form:

In these situations, the linear transformation performed by the linear transformation circuit 230 may also be orthogonal.

3 is a functional block diagram of a multicarrier receiver in accordance with some embodiments of the present invention. Multicarrier receiver 300 may include receive antennas 302 for receiving multicarrier communication signals from a multicarrier transmitter, eg, multicarrier transmitter 100 (FIG. 1). The number of receive antennas 302 used in the multicarrier receiver 300 may be at least as many as the number of transmit antennas 114 (FIG. 1) used by the multicarrier transmitter 100 (FIG. 1). Multicarrier receiver 300 may also include an RF circuit 304 for each receive antenna 302 for downconverting the received signals and generating digital baseband signals. Multicarrier receiver 300 also performs Discrete Fourier Transform (DFT), e.g., Fast Fourier Transform (FFT), on the signals provided by RF circuit 304 to generate frequency-domain signals. Fourier-transform (FT) circuitry 306 may be included for each receive antenna 302. In some embodiments, the frequency-domain signal may be generated for each subcarrier of the multicarrier communication signals received by the multicarrier receiver 300. The multicarrier receiver 300 also decodes the frequency domain signals provided by the FT circuit 306 and determines decision metrics, e.g., decoded soft bits (discussed in more detail below). 315, and a space-time decoder 308 for generating decoded symbols represented by hard bits 317. The soft bits 315 are associated with a corresponding one of the hard bits 317 that can be used in the error correction decoder 312 discussed below to accurately generate the bits of the decoded bit stream 321. It can represent the probability.

Multicarrier receiver 300 may also include, among other things, a channel estimator 320 for generating channel estimates H for use in the space-time decoder 308. In some embodiments, the outputs of the space-time decoder 308 include for each subcarrier a pair of symbols representing a QAM constellation point, although the scope of the present invention is not limited in this regard. Multicarrier receiver 300 may also include a symbol demapper 310 for demap hard bits 317 to generate groups of bits. The multicarrier receiver 300 may also include an error correction decoder 312 for decoding the groups of bits generated by the symbol mapper 310 to produce a decoded bit stream 321. Multicarrier receiver 300 may also include other functional elements not specifically illustrated to facilitate understanding.

In some embodiments, channel estimation performed by channel estimator 320 may be based on OFEM training symbols (ie, preambles). In these embodiments, channel estimates generated from the preambles may be used to process OFDM symbols in subsequent transmission bursts, although the scope of the present invention is not limited in this respect.

In some embodiments, the error correction decoder 312 may be a forward error-correcting (FEC) decoder, for example a turbo decoder, and using soft bits 315 to encode the bit. Decode 319. In some embodiments, error correction decoder 312 may use convolutional decoding or Reed-Solomon decoding, or a combination thereof, although the scope of the present invention is limited in this regard. It is not. In some other embodiments, the error correction decoder 312 may use turbo decoding or low-density parity-check (LDPC) decoding as well as other encoding / decoding techniques using soft bits 315. Also available.

According to some embodiments, for each receive antenna 302, the space-time decoder 308 may derive objective functions from the received signal matrix y _n 311, The hard bits 317 can be generated by minimizing the objective functions, and the soft bits 315 can be generated by solving a set of linear equations of the objective functions. In these embodiments, the space-time decoder 308 selects, for example, one of the selected linear transformation matrices for each subcarrier of the multicarrier signals received via the respective receive antennas 302. Quasi-orthogonal space-time block decoding can be performed using the linear transformation matrix 261 (FIG. 2) (ie, one of U ₁ , U ₂ , U ₃ ). The selected linear transformation matrix may correspond to the linear transformation matrix used by the multicarrier transmitter 100 (FIG. 1) to space-time encode the multicarrier signals for transmission. In some embodiments, the space-time decoder 308 receives respective transmit antennas 114 (FIG. 1) of the multicarrier transmitter 100 (FIG. 1) and each receive of the multicarrier receiver 300. A channel estimation matrix H can be used that can be estimated for the plurality of wireless channels between the antennas 302. These examples are discussed in more detail below.

Although some embodiments of the present invention are described as using at least four receive antennas 302, the scope of the present invention is not limited in this respect because other numbers of transmit antennas may also be used. Receive antennas 302 may be directional, including, for example, dipole antennas, monopole antennas, patch antennas, loop antennas, microstrip antennas, or other types of antennas suitable for transmission of RF signals. It may include one or more omnidirectional antennas. In some MIMO embodiments, instead of two or more antennas, one antenna with multiple apertures may be used. In these embodiments, each aperture may be considered a separate antenna. In some embodiments, each antenna may be effectively separated to take advantage of different channel characteristics and spatial diversity that may occur between each receive antenna 302 and another wireless communication device. In some embodiments, receive antennas 302 may be separated by one tenth or more of the wavelength.

4 is a functional diagram of a space-time decoder according to some embodiments of the present invention. Space-time decoder 400 may be suitable for use as space-time decoder 308 (FIG. 3), but other configurations for space-time decoder 308 (FIG. 3) may also be suitable. have. The space-time decoder 400 includes a processing circuit 402 for deriving objective functions, a processing circuit 406 for minimizing objective functions, and a processing circuit 404 for solving linear equations. In these embodiments, the processing circuit 402 may derive the objective functions 413 from the received signal matrix y _n 411 using one of the linear transformation matrices 410. The processing circuit 406 may use the channel estimation matrix (H) 412 to minimize the objective functions 413 to generate decoded hard bits 417. The processing circuit 404 may solve the system of linear equations based on the objective functions 413 and the channel estimation matrix (H) 412 to produce the decoded soft bits 415. In some embodiments, space-time decoder 400 may perform these operations on each subcarrier of the received multicarrier signals. In these embodiments, the received signal matrix 411 is one of the received signal matrices 311 (FIG. 3) generated for each subcarrier via all receive antennas 302 (FIG. 3). Correspondingly, each received signal matrix 411 may be able to include an input from each receive antenna 302 (FIG. 3). In these embodiments, decoded soft bits 415 may correspond to soft bits 315 (FIG. 3), and decoded hard bits 417 may correspond to hard bits 317 (FIG. 3). It can respond. In these embodiments, channel estimation matrix (H) 412 may be generated by channel estimator 320 (FIG. 3), and one of linear transformation matrices 410 is linear transformation matrices 261 ( May correspond to one of FIG. 2).

According to some embodiments, the received signal matrix 411 may be represented by the following equation:

In this equation, Y _n represents the received signal on the nth subcarrier, H represents the channel matrix for the nth subcarrier, and Q represents a quasi-orthogonal space-time block code used to encode the signal at the transmitter. x denotes decoded signals and W denotes additive channel noise.

By applying one of the aforementioned linear transformation matrices and removing the subcarrier index n, the maximum likelihood decoding is achieved by the space-time decoder 400 based on one of the following equations: Can:

는 목적 함수들을 나타내는데, 여기에서 r_i 및 s_i는 소프트 비트들(415)을 나타낸다. 상기 수학식에 나타난 것과 같이, 원래의 여덟 개의 요소로 된 집합의 실수 변수 탐색(eight-tuple real variable searching) 은 두 개의 요소로 된 집합의 실수 변수 탐색의 네 배가 된다. 이것은, 하나의 복소수 심볼 탐색의 경우와 대략 동일한 복잡도를 가질 수 있는데, 이 복잡도는, 변환 행렬 U₁이 U에 이용될 때의 아라모우티 코딩의 복잡도와 동일한 복잡도이다. 이들 실시예들에서, 상기의 수학식은 다음과 같이 될 수 있다:In these equations,

Denotes objective functions, where r _i and s _i represent soft bits 415. As shown in the above equation, the original eight-tuple real variable searching is four times that of the two-element set. This may have roughly the same complexity as in the case of one complex symbol search, which is the same complexity as that of the aramouti coding when the transformation matrix U ₁ is used for U. In these embodiments, the equation above may be as follows:

Based on the above, the processing circuit 402 can derive the objective functions 413 as follows. In some embodiments, rotation using R ₁ and U ₁ may be performed for the square QAM signal constellation described above.

In these embodiments, the channel estimate H in the MIMO system can be expressed as follows:

The received signal matrix Y can be expressed as follows:

In these equations, M represents the number of transmit antennas, N represents the number of receive antennas, and T represents the number of time-slots (ie, T OFDM symbols). In some embodiments using four transmit antennas (M = 4) and four receive antennas (N = 4), for four time slots (T = 4), the following equations give four transmissions: It may represent a signal transmitted by the antennas.

, 및

, And

By algebraic manipulation, the objective functions 413 can be derived by the processing circuit 402 as follows:

Processing circuitry 406 may operate on these objective functions to generate decoded hard bits 417 that may represent the output of maximum likelihood decoding. In some embodiments, processing circuit 406 may minimize the objective functions using the following equation to generate decoded hard bits 417:

In these embodiments, r _k and r _s represent decoded hard bits 417 corresponding to the symbols transmitted at the four transmit antennas.

On the other hand, the processing circuit 404, instead of the constellation set S, which may be a discrete signal constellation set, in terms of real values r _i and s _i on the real line, the objective functions 413 (eg For example, by minimizing the four objective functions represented by f _i (r _i , s _i ) shown above, soft bits 415 can be generated from the maximum likelihood decoding. Since the objective functions f _i (r _i , s _i ) are quadratic forms of the real variables r _i and s _i , the minimum and soft output of the maximum likelihood decoding is determined by the processing circuit 404 by: It can be determined by solving the following 2x2 linear equations:

Decoded soft bits 415 generated from solving these equations may be used by an error correction decoder, eg, error correction decoder 312 (FIG. 3). In some embodiments, the solutions of the 2x2 linear equations may be improved using minimum mean square estimation (MMSE), although the scope of the present invention is not limited in this respect.

In some embodiments described above, the coding gain is fast maximum likelihood decoding with approximately the same complexity as in the case of aramouti decoding, for space-time coding for MIMO OFDM systems with four transmit antennas. Can be maximized when

1 through 4, although the multicarrier transmitter 100, the space-time encoder 200, the multicarrier receiver 300, and the space-time decoder 400 are illustrated as having several separate functional elements. One or more of the functional elements may be combined, a combination of software-configured elements, eg, processing including digital signal processors (DSPs), and / or other hardware elements. It can be implemented by elements. For example, some elements may 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. . In some embodiments, illustrated functional elements may refer to one or more processes that operate on one or more processing elements.

In some embodiments, multicarrier transmitter 100 and / or multicarrier receiver 300 may be part of one or more wireless communication devices capable of communicating OFDM communication signals over a multicarrier communication channel. The multicarrier communication channel may be within a predetermined frequency spectrum and may include a plurality of orthogonal subcarriers. In some embodiments, multicarrier signals may be defined by closely spaced OFDM subcarriers. Each subcarrier may have null at the virtual center frequency of the other subcarriers and / or each subcarrier may have integer cycles within a symbol period, The scope of the invention is not limited in this respect. In some embodiments, the multicarrier transmitter 100 and / or the multicarrier receiver 300 can communicate in accordance with a multiple access technique, eg, orthogonal frequency division multiple access (OFDMA). However, the scope of the present invention is not limited in this respect.

In some embodiments, multicarrier transmitter 100 and / or multicarrier receiver 300 may be a communication station, eg, a wireless fidelity (WiFi) communication station, an access point (AP), or mobile station (MS). May be part of a wireless local area network (WLAN) communication station. In some other embodiments, the multicarrier transmitter 100 and / or the multicarrier receiver 300 may be a broadband wireless access (BWA) network communication station, such as Worldwide Interoperability for Microwave Access (WiMax) communication. The scope of the present invention is not limited in this respect, although it may be part of a station, since multicarrier transmitter 100 and / or multicarrier receiver 300 may be part of almost any wireless communication device.

In some embodiments, multicarrier transmitter 100 and / or multicarrier receiver 300 may comprise a portable wireless communication device, such as a personal digital assistant (PDA), a wireless communication function. Laptop or portable computer, web tablet, cordless phone, wireless headset, pager, instant messaging device, digital camera, access point, television, medical device (e.g. , Heart rate monitor, blood pressure monitor, etc.) or any other device capable of wirelessly transmitting and / or receiving information.

In some embodiments, the frequency spectrum of the communication signals received by the multicarrier transmitter 100 and / or the multicarrier receiver 300 may include a 5 GHz frequency spectrum or a 2.4 GHz frequency spectrum. In these embodiments, the 5 GHz frequency spectrum includes frequencies in the range of approximately 4.9 to 5.9 GHz and the 2.4 GHz frequency spectrum includes frequencies in the range of approximately 2.3 to 2.5 GHz, but other frequency spectrums are equally suitable as well. Therefore, the scope of the present invention is not limited to this point. In some BWA network embodiments, the frequency spectrum of the communication signals may include frequencies between 2 and 11 GHz, although the scope of the present invention is not limited in this respect.

In some embodiments, the multicarrier transmitter 100 and / or the multicarrier receiver 300 may include specific communication standards, eg, IEEE 802.11 (a), 802.11 (b), 802.11 (g), 802.11 (h). Multicarrier transmitter 100 and / or multicarrier receiver 300, although the signals may be communicated in accordance with the proposed specification for IEEE standards and / or wireless local area networks, including 802.11 (n) standards. In addition, the scope of the present invention is not limited in this respect as it may be suitable for transmitting and / or receiving communications in accordance with other techniques and standards.

In some broadband radio access network embodiments, the multicarrier transmitter 100 and / or the multicarrier receiver 300 may include the IEEE 802.16-2004 and IEEE 802.16 (e) standards for wireless metropolitan area networks (WMAN). Multicarrier transmitter 100 and / or multicarrier receiver 300 may also transmit and / or receive communications in accordance with other techniques and standards. The scope of the present invention is not limited in this respect as it may be suitable also for the following. For more information about the IEEE 802.11 and IEEE 802.16 standards, see "IEEE Standards for Information Technology-Telecommunications and Information Exchange between Systems"-Local Area Networks-Specific Requirements-Part 11 "Wireless LAN Medium Access Control (MAC) and See Physical Layer (PHY), ISO / IEC 8802-11: 1999 ", and Metropolitan Area Networks-Specific Requirements-Part 16:" Air Interface for Fixed Broadband Wireless Access Systems "(May 2005) and related revisions / versions. Let's do it.

Unless specifically stated otherwise, terms such as processing, computing, calculating, determining, displaying, etc., refer to the physical and physical (eg, One or more processing or computing systems, or similar devices, or other capable of manipulating and converting data expressed in electrical quantities into other data similarly represented in physical quantities in registers or memories of the processing system It may refer to the action and / or process of storing, transmitting or displaying such information. In addition, as used herein, a computing device includes one or more processing elements coupled with computer readable memory, which may be volatile or nonvolatile memory, or a combination thereof.

Some embodiments of the invention may be implemented in one or a combination of hardware, firmware and software. Some embodiments of the invention may also be embodied as instructions stored on a machine readable medium, which may be read and executed by at least one processor, to perform the operations disclosed herein. Machine-readable media can include any mechanism for storing or transmitting information in a form readable by a machine (eg, a computer). For example, a machine-readable medium may include read-only memory (ROM), random-access memory (RAM), magnetic disk storage media, optical storage media, flash memory devices, electrical, optical, acoustical or otherwise. Other types of propagated signals (eg, carrier waves, infrared signals, digital signals, etc.), and others.

This abstract requires 37 C.F.R. It is provided to comply with Section 1.72 (b). This summary 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 within one embodiment for the purpose of streamlining the disclosure. The method of this disclosure should not be construed as reflecting the intention of embodiments of the claimed subject matter to require more features than are explicitly listed in each claim. Rather, as indicated in the following claims, the invention may reside in fewer features than all features of one disclosed embodiment. Accordingly, the following claims are hereby incorporated into the detailed description, with each claim standing on its own as a separate preferred embodiment.

Claims (19)

A method of space-time encoding multicarrier signals performed by a space-time encoder, the method comprising: Linearly transforming input symbols of a constellation set using the selected transformation matrix to produce linearly transformed symbols; Forming a complex symbol for each of a plurality of transmit antennas from the linearly transformed symbols; Forming code matrices from the complex symbols; And Generating a quasi-orthogonal space-time matrix from the code matrices for use in generating multicarrier signals for transmission by the transmit antennas And a space-time encoding method of the multicarrier signals. 2. The system of claim 1, further comprising: in one dimension of the quasi-orthogonal space-time matrix for transmission by one of the transmit antennas on a plurality of subcarriers comprising the multicarrier signals. Transforming the sequence of symbols represented by the space-time encoding method of the multicarrier signals. The method of claim 2, wherein the further transforming step comprises: for each of the plurality of transmit antennas: Performing an inverse Fourier transform on each of the symbols of the one dimension of the quasi-orthogonal space-time matrix to produce a time-domain waveform; And Upconverting the time-domain waveform for transmission by an associated transmit antenna of the transmit antennas, Wherein each of the plurality of transmit antennas simultaneously transmits information represented by the groups of symbols of the one dimension of the quasi-orthogonal space-time matrix. 3. The method of claim 2, wherein forming the code matrices comprises generating Alamouti code matrices from the linearly transformed symbols. And wherein the quasi-orthogonal space-time matrix comprises a matrix of the Aramouti code matrices. The method of claim 1, Generating a quadrature amplitude modulation constellation set from the initial bit stream; And Mapping the bits of the constellation set to a plurality of complex symbols corresponding to the number of transmit antennas, The linear transforming step includes linearly transforming the mapped plurality of complex symbols using the selected transform matrix to produce a plurality of real symbols. As a space-time encoder, A linear transformation circuit for linearly transforming input symbols of the constellation set using the selected transformation matrix to produce linearly transformed symbols; A complex symbol generator for forming a complex symbol for each of a plurality of transmit antennas from the linearly transformed symbols; A code matrix former for forming code matrices from the complex symbols; And Quasi-orthogonal space-time matrix generator for generating a quasi-orthogonal space-time matrix from the code matrices for use in generating multicarrier signals for transmission by the transmit antennas Space-time encoder comprising a. 7. The method of claim 6, wherein the sequence of symbols represented by one dimension of the quasi-orthogonal space-time matrix is transmitted to one of the transmit antennas on the plurality of subcarriers comprising the multicarrier signals. A space-time encoder that is transformed for transmission. 8. The method of claim 7, wherein for each of the plurality of transmit antennas an inverse Fourier transform is performed on each of the symbols of the one dimension of the quasi-orthogonal space-time matrix to generate a time-domain waveform, The time-domain waveform is upconverted for transmission by an associated transmit antenna of the transmit antennas, Each of the plurality of transmit antennas simultaneously transmits information represented by the groups of symbols of the one dimension of the quasi-orthogonal space-time matrix. 8. The method of claim 7, wherein the code matrix former generates an aramouti code matrices from the linearly transformed symbols, And said quasi-orthogonal space-time matrix generator generates said quasi-orthogonal space-time matrix including a matrix of said aramiuti code matrices. The method of claim 6, A constellation set generator for generating the constellation set from an initial bit stream; And A symbol mapper for mapping the bits of the constellation set to a plurality of complex symbols corresponding to the number of transmit antennas, The constellation set includes a quadrature amplitude modulation constellation set, And the linear transform circuit linearly transforms the mapped plurality of complex symbols using the selected transform matrix to produce a plurality of real symbols. A method of decoding received multicarrier signals performed by a space-time decoder, the method comprising: Converting the received signal matrix into a set of objective functions, the objective functions being functions of soft bits; Performing a mathematical operation on the objective functions to generate decoded hard bits for symbol demapping; And Solving a set of linear equations generated from the objective functions to produce decoded soft bits for use in error correction decoding. And decoding the received multicarrier signals. 12. The method of claim 11, wherein the converting, performing a mathematical operation, and obtaining a solution comprise: giving orthogonal space-time for each subcarrier of the multicarrier signals received via a plurality of antennas coupled to the multicarrier receiver. Performing block decoding, The transforming step includes using a selected transform matrix among a plurality of transform matrices, Wherein the selected transform matrix corresponds to a transform matrix used for space-time encoding the multicarrier signals by a multicarrier transmitter for transmission to the multicarrier receiver. 13. The method of claim 12, wherein performing the mathematical operation and obtaining a solution comprises using a channel estimation matrix estimated for a plurality of wireless channels between the multicarrier transmitter and the multicarrier receiver. A method of decoding received multicarrier signals. 13. The method of claim 12, wherein the multicarrier signals comprise orthogonal frequency division multiplexed signals received via a plurality of antennas. 14. The cyclic prefix of claim 13 wherein for each subcarrier, the multicarrier signals received via each of the antennas prior to the space-time block decoding to generate the received signal matrix. removing (cyclic prefix; CP) and performing a multi-point Fourier transform. As a multicarrier receiver, Fourier transform circuit for generating a received signal matrix for each subcarrier from the received multicarrier signals; And Space-time decoder for generating decoded soft bits and decoded hard bits from the received signal matrices Including, The decoded soft bits represent probabilities for use in error correction decoding, The decoded hard bits represent bits before symbol demapping, The space-time decoder converts the received signal matrix into a set of objective functions, performs a mathematical operation on the objective functions to generate the decoded hard bits, and generates the decoded soft bits. And a processing circuit for solving a system of linear equations generated from said objective functions. The method of claim 16, A symbol demapper for demaping the decoded hard bits to produce blocks of demapped bits; And And an error correction decoder for performing error correction decoding operations on the blocks of demapped bits using the decoded soft bits to produce a decoded bit stream. The method of claim 16, wherein the processing circuit, Perform quasi-orthogonal space-time block decoding on each of the subcarriers of the multicarrier signals received via a plurality of antennas connected to the multicarrier receiver, Using a selected transformation matrix among a plurality of transformation matrices, Wherein the selected transform matrix corresponds to a transform matrix used for space-time encoding of the multicarrier signals by a multicarrier transmitter for transmission to the multicarrier receiver. 19. The apparatus of claim 18, wherein the processing circuitry is configured for a plurality of wireless channels between the multicarrier transmitter and the multicarrier receiver to perform mathematical operations on the objective functions and to solve the system of linear equations. Multicarrier receiver using an estimated channel estimation matrix.

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