Title of Invention

TRANSMITTING AND RECEIVING CODED INFORMATION IN A MIMO COMMUNICATION SYSTEM

Abstract

A method of receiving information includes receiving a vector of signal values for a transmitted codeword in antennas of a MIMO receiver array in each of a sequence of time slots. Each vector forms one row of a matrix Y. Each antenna receives the signal values of one column of the matrix Y over the sequence of time slots such that one of the antennas receives the signal values of each column of the matrix Y. The method also includes evaluating a vector S (0,..., 0) for an associated zero m-component vector (0,..., 0). The vector S (0,..., 0) is given by a Jacamars transform of the diagonal part of the square matrix Y-Y .

Full Text

CODING IN A MIMO COMMUNICATION SYSTEM BACKGROUND This is a continuation-in-part application of Application No. 11/219,126, filed September 2,2005. Field of the Invention The invention relates to multiple-input-multiple-output (MIMO) communication systems and methods of operating MIMO systems. Discussion of the Related Art A MIMO communication system includes a transmitter with multiple transmitting antennas, a receiver with multiple receiving antennas, and a free space channel coupling the transmitting and receiving antennas. The transmitting antennas transmit on the same frequency band in each time slot. For that reason, a transmitter having M transmitting antennas can be viewed as sending a row of M signal values in each time slot. If the transmitter transmits a message over T time slots, the message is associated with a Tim dimensional matrix, U, of signal values. The free space channel couples the multiple transmitting antennas to various ones of the receiving antennas. Thus, in each time slot, individual receiving antennas receive a signal combining transmitted signals from more than one of the transmitting antennas. A transmission matrix, H, whose elements are the complex channel attenuations between various pairs of transmitting and receiving antennas, defines these combinations. In T time slots, N receiving antennas will receive a message that is described by a TxN dimensional matrix Y. The matrix Y approximately satisfies Y = U-G-H + w where w is an additive noise matrix and G is a diagonal matrix of transmission gains. Thus, knowledge of the transmission matrix, H, can enable the MIMO receiver to disentangle the signals transmitted by different ones of the transmitting antennas, e.g., if H is invertible. For that reason, it is sometimes desirable to measure the transmission matrix, H. One method of measuring H, involves transmitting standard pilot beams from various ones of the transmitting antennas and measuring the signals received in response to the transmission of the standard pilot beams. Unfortunately, the use of pilot beams is not convenient in all MIMO communication systems. For example, the uses of such pilot beams may not be enable measurements of the transmission matrix, H, for a channel whose properties are changing rapidly. In such MIMO communication systems, decoding is performed without a detailed knowledge of the transmission matrix. BRIEF SUMMARY Various embodiments provide for apparatus and method for operating portions of MIMO communication systems with advantageous codebooks. In one aspect, an apparatus is able to transmit a sequence of messages via a MIMO channel. The apparatus includes a MIMO transmitter. The MIMO transmitter has an array of antennas, is capable of selecting any codeword of a codebook, and is configured to select one of the codewords in response to receiving each message of the sequence. Each codeword of the codebook is a matrix. For each one of the selected codewords, the transmitter is configured to transmit signals from the antennas in a series of time slots corresponding to the one of the selected codewords such that the array transmits one column of the one of the selected codewords from each antenna and such that one row of the one of the selected codewords is transmitted in each of the time slots of the corresponding series. The transmitter is configured such that each of the codewords of the codebook is equal to a matrix m annoyer aspect, an apparatus micas a Mime receiver. Ire MIMO receiver includes an array of antennas. The receiver is configured to receive a vector of signal values for a transmitted codeword via the antennas in each of a sequence of time slots. Each vector forms one row of a matrix Y. The receiver is such that each antenna receives the signal values of one column of the matrix Y over the sequence of time slots such that the signal values of each column of the matrix Y are received in one of the antennas of the array. The receiver is configured to evaluate a vector S (0,..., 0) for a zero m-component vector (0,..., 0) from the received signal values. The vector S (0,..., 0) is given by a Hadamard transform of the diagonal part of the square matrix Y-Y^ BRIEF DESCRIPTION OF THE DRAWINGS Various embodiments are described in the Figures and Detailed Description of Illustrative Embodiments. Nevertheless, the invention may be embodied in various forms and is not limited to the embodiments described in the Figures and Detailed Description of Illustrative Embodiments. Figure 1 is a schematic view of a multiple-input-multiple-output (MIMO) contraindication system; Figure 2 is a flowchart illustrating an exemplary method of communicating using the MIMO communication system of Figure 1; and Figure 3 is a flowchart illustrating a method of decoding MIMO communications that have been coded according to a U^-standard codebook, e.g., as in the method of Figure 2; and Figure 4 is a block diagram for an apparatus configured to perform the decoding method of Figure 3. In the Figures and text, like reference numerals indicate elements with similar functions. DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS 1. MIMO Communication System Figure 1 illustrates a multiple-input-multiple-output (MIMO) communication system 10. The system includes a transmitter 12, a confimunication channel 13, and a receiver 14. The transmitter 12 has an array 15 of M transmission antennas 16i, ..,,16M. The channel 13 is, e.g., typically a free-space channel with a number of signal-scatterers therein (not shown). The receiver 14 has an array 17 of reception antennas 18I,...,18N. The transmission and reception arrays 15,17 may have the same or different numbers of antennas. That is, the positive integers "M" and "N" may be equal to or different. The number M is greater than 1 for a MIMO transmitter and is, e.g., preferably equal to 2™"^ where "m" is a positive integer greater than 1, e.g., m = 2, 3,4, 5, 6,7, 8,9,10, or more. The characteristics of the MIMO communication system 10 include transmission gains, a TxN-dimensional noise matrix w, and an MxN transmission matrix H. The transmission gains are ratios of the amplitudes of output signals over input signals at the transmission antennas 16i,. ..,16M. In the exemplary array 15, each transmission gain is equal to (p/M) . In other embodiments, one or more of the transmission antennas 16i, ... ,16M may have different transmission gains. The noise matrix w describes additive noise at the array 17. In particular, component "wtj" of the noise matrix w is the additive noise at associated reception antenna 18j at communication time slot "t". The transmission matrix, H, describes the channel attenuation, i.e., including amplitude and phase, between the transmission and reception arrays 15,17, In particular, the (j, k) component, Hjk, describes the coupling between the transmission antenna 16j and the reception antenna 18k. 2. MIMO Communications Figure 2 illustrates a method 20 of operating the MIMO conununication system 10 of Figure 1. The MIMO communication system 10 is able to send L types of messages from the transmitter 12 to the receiver 14. In particular, each message corresponds to one codeword in a reselected codebook having L codewords. Each codeword is a TxM matrix with a vector identifier "d" that uniquely identifies a single codeword. The method 20 includes selecting a codeword to transmit, wherein the selected codeword corresponds to the next message "d" awaiting transmission to the MIMO receiver 14 (step 22). The set of available codewords forms a U -standard codebook. A U -standard codebook has L different codewords where the number L is less than or equal to - 2 as described below. The method 20 includes transmitting the U standard codeword that corresponds to the message "d" from the MIMO transmitter 12 to the MIMO receiver 14 (step 24). The transmitter 12 transmits the codeword, in a row-by-row manner over a sequence of T time slots, e.g., consecutive slots of equal length. In a time slot "t" of the sequence, the transmitter 12 transmits row "t" of the particular TxM matrix codeword, Dud, that corresponds to the selected message. In each time slot, the antennae 16i, .. .,16M of the transmitter 12 simultaneously transndt signals on the same frequency band. For example, antenna 16k of the transmitter 12 transmits a corresponding signal of amplitude (p/M) Etch in a time slot "t". Over the T time slots for transmitting the selected codeword Dud, the antenna 16k of the transmitter 12 transmits a corresponding column of the selected codeword Dud- In particular, the k-to antenna 16k transmits the k-th column of the selected codeword Dud during the T time slots corresponding to the message "d". During T time slots, the method 20 includes receiving in the reception antennas 181,..., 1 8N signal amplitudes that together correspond to the transmitted codeword, Dud (step 26). During the T transmission time slots for the message "d", the reception antennas 18i,. ..,18N together receive a TxN dimensional matrix Y of signal amplitudes. In particular, one row of Y is received in each of the time slots for the message "d". Over the whole set of time slots for the message "d", the j-to reception antenna 18j receives the j-th column of the matrix Y. The received matrix Y can be motorized by Y = (p/M) Do-H + w. Here, w is an additive noise matrix, e.g., channel and electronics noise. The method 20 includes decoding the matrix Y of signal amplitudes received by the reception antennae 18i,..., 18N during the T signaling periods to determine which the identity of the transmitted codeword and thus, to determine the identity of the message transmitted (step 28). The decoding determines the identifier "d" of the transmitted U^-standard codeword. In particular, the receiver 14 decodes the matrix Y based on its knowledge of the U^-standard codebook to determine "d". Furthermore, the maximum likelihood-decoding algorithm does not require knowledge of the channel's transmission matrix, H. For that reason, this algorithm may be advantageous in embodiments where measuring H is inconvenient. For example, such situations occur when channel properties change too fast to conveniently measure H by using pilot beams. Nevertheless, it is preferable that channel properties are substantially constant over the T time slots used to transmit a codeword even if the channel properties vary too fast to conveniently measure the transmission matrix H. The method 20 includes performing steps 22, 24, 26, and 28 for each message to be transmitted. Thus, the method 20 allows communication of a sequence of selected messages between the transmitter 12 and receiver 14 of the MIMO communication system 10. To perform the MIMO communication method 20, both the transmitter 12 and receiver 14 of Figure 1 need to know the identity of the U* standard codebook that is used for coding messages. Different embodiments may use different U -standard codebooks. The forms and construction of such codebooks are described below. matrix. Thus, the last expression explains the origin of the step 52 in the loop execution of the method 40. Figure 4 shows an exemplary apparatus 70 for performing the decoding according to the method 40 of Figure 3. The apparatus 70 includes an input/output device 72, a data storage device 74, a bus 76, a RAM memory 78, and a general processor 80. The input/output device 72 delivers the matrix Y signal amplitudes, which the antennas 18i, ... ,18N of Figure 1 received from the channel 13, to the data storage device 74. The data storage device 74 stores data and a program of machine executable instructions. The machine executable instructions, e.g., encode the steps of the method 40 of Figure 3. The bus 76 transports said instructions and/or data between the input/output device 72, the data storage device 74, the memory 78, and the processor 80. The processor 108 is capable of executing the program of machine executable instructions to manipulate and process the data in the data storage device 74 thereby perform the method 40 of decoding the received matrix Y to determine which codeword was transmitted. In other embodiments, a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), or a digital signal processor (DSP) may be configured to perform the decoding method 40 as shown in Figure 3. From the disclosure, drawings, and claims, other embodiments of the invention will be apparent to those skilled in the art. What is claimed is: 1. An apparatus for transmitting a sequence of messages via a Middle channel, comprising: a MMO transmitter having an array of antennas, being capable of selecting any codeword of a codebook, and being configured to select one of the code words in response to receiving each message of the sequence, each codeword being a matrix; and wherein for each one of the selected codewords the transmitter is configured to transmit signals from the antennas in a series of time slots corresponding to the one of the selected codewords such that each antenna transmits one colunm of the one of the selected codewords and such that one row of the one of the selected codewords is transmitted in each of the time slots of the corresponding series; and wherein the transmitter is configured such that each of the codewords is a matrix 2. A method of receiving information, comprising: in each of a sequence of time slots, receiving a vector of signal values for a transmitted codeword in antennas of a MIMO receiver array, each vector forming one row of a matrix Y, each antenna receiving the signal values of one column of the matrix 4. The method of claim 3, wherein the steps of evaluating Hadamard transforms of the diagonal parts of the s are performed for each nonzero vector belonging to {0,1}. 5. The method of claim 3, further comprising : identifying a particular one of the Hadamard transforms that has a component whose magnitude is of equal or larger magnitude than the components of the others of the Hadamard transforms. 6. The method of claim 4, further comprising : identifying a particular zero or nonzero vector (a,,..., a ) whose associated one of the Hadamard transforms has a component whose magnitude is of equal or larger magnitude than the components of the other Hadamard transforms; and identifying an index of a largest magnitude component in the one of the Hadamard transforms. 7. An apparatus, comprising: a MIMO receiver including an array of antennas, the receiver being configured to receive a vector of signal values for a transmitted codeword via the antennas in each of a sequence of time slots, each vector forming one row of a matrix Y, the receiver is such that each antenna receives the signal values of one column of the matrix Y over the sequence of time slots such that the signal values of each column of the matrix Y are received in one of the antennas of the array; and wherein the receiver is configured to evaluate a vector S (0,..., 0) for a zero m- component vector (0,..., 0) from the received signal values, the vector S (0,..., 0) being given by a Hadamard transform of the diagonal part of the square matrix Y-Y . 8. The apparatus of claim 7, wherein the receiver is configured to evaluate a vector S(a) for a plurality of nonzero m-component vectors whose components belong to the set {0, 1}, each vector S(a) being a Hadamard transform of the

Documents:

6020-CHENP-2007 EXAMINATION REPORT REPLY RECEIVED 30-08-2013.pdf

6020-CHENP-2007 EXAMINATION REPORT REPLY RECEIVED 24-09-2012.pdf

6020-CHENP-2007 FORM-1 30-08-2013.pdf

6020-CHENP-2007 FORM-3 30-08-2013.pdf

6020-CHENP-2007 OTHER DOCUMENT 30-08-2013.pdf

6020-CHENP-2007 OTHER PATENT DOCUMENT 30-08-2013.pdf

6020-CHENP-2007 AMENDED CLAIMS 30-08-2013.pdf

6020-CHENP-2007 AMENDED PAGES OF SPECIFICATION 30-08-2013.pdf

6020-CHENP-2007 CORRESPONDENCE OTHERS 19-06-2013.pdf

6020-CHENP-2007 FORM-3 19-06-2013.pdf

6020-chenp-2007-abstract.pdf

6020-chenp-2007-claims.pdf

6020-chenp-2007-correspondnece-others.pdf

6020-chenp-2007-description(complete).pdf

6020-chenp-2007-drawings.pdf

6020-chenp-2007-form 1.pdf

6020-chenp-2007-form 26.pdf

6020-chenp-2007-form 3.pdf

6020-chenp-2007-form 5.pdf