Abstract:
A method of communicating data to M receiving antennas from N transmitting antennas, where M and N are integers, the method includes the steps of receiving M data signals from M receive antennas, applying the M data signals to a space/time decoder to produce M decoded streams and reconstructing original data transmitted via N transmit antennas from the M decoded streams. At least P transmitting antennas transmit space-time block-coded signals and (N-P) transmitting antennas transmit code signals through spatial division multiplexing, where P is an integer.

Description:
REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority of U.S. Provisional Patent Application Ser. No. 60/604,050, filed Aug. 25, 2004. The subject matter of this earlier filed application is hereby incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Technical Field of the Invention 
         [0003]    This invention relates generally to wireless communication systems and more particularly to a transmitter transmitting at high data rates with such wireless communication systems. Additionally, the present invention allows the detection and reception of multiple data streams for higher data rates. 
         [0004]    2. Description of Related Art 
         [0005]    Communication systems support wireless and wire lined communications between wireless and/or wire lined communication devices. Such communication systems range from national and/or international cellular telephone systems to the Internet to point-to-point in-home wireless networks. Each type of communication system is constructed, and hence operates, in accordance with one or more communication standards. For instance, wireless communication systems may operate in accordance with one or more standards including, but not limited to, IEEE 802.11, BLUETOOTH™, advanced mobile phone services (AMPS), digital AMPS, global system for mobile communications (GSM), code division multiple access (CDMA), local multi-point distribution systems (LMDS), multi-channel-multi-point distribution systems (MMDS), and/or variations thereof. 
         [0006]    For each wireless communication device to participate in wireless communications, it may include a built-in radio transceiver (i.e., receiver and transmitter) or may be coupled to an associated radio transceiver (e.g., a station for in-home and/or in-building wireless communication networks, RF modem, etc.). The transmitter may include a data modulation stage, one or more intermediate frequency stages, and a power amplifier. The data modulation stage converts raw data into baseband signals in accordance with a particular wireless communication standard. The one or more intermediate frequency stages mix the baseband signals with one or more local oscillations to produce RF signals. The power amplifier amplifies the RF signals prior to transmission via an antenna. 
         [0007]    The transmitter may include a data modulation stage, one or more intermediate frequency stages, and a power amplifier. The data modulation stage can convert raw data into baseband signals in accordance with a particular wireless communication standard. The one or more intermediate frequency stages mix the baseband signals with one or more local oscillations to produce RF signals. The power amplifier amplifies the RF signals prior to transmission via an antenna. 
         [0008]    The transmitter includes at least one antenna for transmitting the RF signals, which are received by a single antenna, or multiple antennas, of a receiver. When the receiver includes two or more antennas, the receiver will select one of them to receive the incoming RF signals. In this instance, the wireless communication between the transmitter and receiver is a single-output-single-input (SOSI) communication, even if the receiver includes multiple antennas that are used as diversity antennas (i.e., selecting one of them to receive the incoming RF signals). For SISO wireless communications, a transceiver includes one transmitter and one receiver. 
         [0009]    Other types of wireless communications include single-input-multiple-output (SIMO), multiple-input-single-output (MISO), and multiple-input-multiple-output (MIMO). In a SIMO wireless communication, a single transmitter processes data into radio frequency signals that are transmitted to a receiver. The receiver includes two or more antennas and two or more receiver paths. Each of the antennas receives the RF signals and provides them to a corresponding receiver path (e.g., LNA, down conversion module, filters, and ADCs). Each of the receiver paths processes the received RF signals to produce digital signals, which are combined and then processed to recapture the transmitted data. 
         [0010]    For a multiple-input-single-output (MISO) wireless communication, the transmitter includes two or more transmission paths (e.g., digital to analog converter, filters, up-conversion module, and a power amplifier) that each converts a corresponding portion of baseband signals into RF signals, which are transmitted via corresponding antennas to a receiver. The receiver includes a single receiver path that receives the multiple RF signals from the transmitter. In this instance, the receiver uses beam forming to combine the multiple RF signals into one signal for processing. 
         [0011]    For a multiple-input-multiple-output (MIMO) wireless communication, the transmitter and receiver each include multiple paths. In such a communication, the transmitter parallel processes data using a spatial and time encoding function to produce two or more streams of data. The transmitter includes multiple transmission paths to convert each stream of data into multiple RF signals. The receiver receives the multiple RF signals via multiple receiver paths that recapture the streams of data utilizing a spatial and time decoding function. The recaptured streams of data are combined and subsequently processed to recover the original data. 
         [0012]    With the various types of wireless communications (e.g., SISO, MISO, SIMO, and MIMO), providing a diversity of transmitted signals is important to ensure proper data integrity. However, prior art systems do not have the ability to separate and detect signals from multiple streams and realize the full benefits of those multiple streams. Therefore, a need exists for a receiver that has the ability to detect and separate signals from multiple streams so that coding and diversity gain may be realized. 
       BRIEF SUMMARY OF THE INVENTION 
       [0013]    According to one embodiment of the present invention, a method of communicating data to M receiving antennas from N transmitting antennas, where M and N are integers, the method includes the steps of receiving M data signals from M receive antennas, applying the M data signals to a space/time decoder to produce M decoded streams and reconstructing original data transmitted via N transmit antennas from the M decoded streams. At least P transmitting antennas transmit space-time block-coded signals and (N-P) transmitting antennas transmit code signals through spatial division multiplexing, where P is an integer. 
         [0014]    Additionally, the step of reconstructing original data may include determining a number of transmit streams and configurations of those transmit streams through analysis of the M decoded streams. Also, P may be two and the step of receiving M data signals includes receiving two space-time block-coded signals. Also, when N is three, the step of receiving M data signals includes receiving a repetition code signal. Additionally, the step of reconstructing original data may include zero-forcing terms equivalent to relationships between signals sent from the N transmitting antennas to the M receiving antennas to cancel interference. 
         [0015]    According to another embodiment, a receiver for communicating data from N transmitting antennas to M receiving antennas, where M and N are integers, includes receiving means for receiving M data signals via M receive antennas, applying means for applying the M data signals to a space/time decoder to produce M decoded streams and reconstructing means for reconstructing original data transmitted via N transmit antennas from the M decoded streams. At least P transmitting antennas transmit space-time block-coded signals and (N-P) transmitting antennas transmit code signals through spatial division multiplexing, where P is an integer. 
         [0016]    According to another embodiment, a receiver for communicating data from N transmitting antennas to M receiving antennas, where M and N are integers includes M receive antennas, for receiving M data signals, a space/time decoder, configured to produce M decoded streams based on the M data signals and symbol demapping modules, configured to reconstruct original data transmitted via N transmit antennas from the M decoded streams. At least P transmitting antennas transmit space-time block-coded signals and (N-P) transmitting antennas transmit code signals through spatial division multiplexing, where P is an integer. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    For the present invention to be easily understood and readily practiced, the present invention will now be described, for purposes of illustration and not limitation, in conjunction with the following figures: 
           [0018]      FIG. 1  is a schematic block diagram of a wireless communication device in accordance with one embodiment of the present invention; 
           [0019]      FIG. 2  illustrates schematic block diagrams of a transmitter and receiver, with  FIG. 2(   a ) providing a schematic block diagram of an RF transmitter and with  FIG. 2(   b ) providing a schematic block diagram of an RF receiver, in accordance with embodiments of the present invention; 
           [0020]      FIGS. 3(   a ) and  3 ( b ) are a schematic block diagram of a transmitter in accordance one embodiment of with the present invention; 
           [0021]      FIGS. 4(   a ) and  4 ( b ) are a schematic block diagram of a receiver in accordance with one embodiment of the present invention; 
           [0022]      FIG. 5  is a diagram illustrating a Space-Time Block Coding (STBC) method with three transmit antennas to achieve one and a half streams, in accordance with one embodiment of the present invention; 
           [0023]      FIG. 6  is a diagram illustrating another STBC method with a Spatial Division Multiplexing (SDM) component, with three transmit antennas to achieve two streams, in accordance with one embodiment of the present invention; and 
           [0024]      FIG. 7  is a diagram illustrating another STBC method with SDM components, with four transmit antennas to achieve three streams, in accordance with one embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0025]      FIG. 1  is a schematic block diagram illustrating a wireless communication device, according to an example of the invention. The device includes a baseband processing module  63 , memory  65 , a plurality of radio frequency (RF) transmitters  67 ,  69 ,  71 , a transmit/receive (T/R) module  73 , a plurality of antennas  81 ,  83 ,  85 , a plurality of RF receivers  75 ,  77 ,  79 , and a local oscillation module  99 . The baseband processing module  63 , in combination with operational instructions stored in memory  65 , execute digital receiver functions and digital transmitter functions, respectively. The digital receiver functions include, but are not limited to, digital intermediate frequency to baseband conversion, demodulation, constellation demapping, decoding, de-interleaving, fast Fourier transform, cyclic prefix removal, space and time decoding, and/or descrambling. The digital transmitter functions include, but are not limited to, scrambling, encoding, interleaving, constellation mapping, modulation, inverse fast Fourier transform, cyclic prefix addition, space and time encoding, and/or digital baseband to IF conversion. The baseband processing module  63  may be implemented using one or more processing devices. Such a processing device may be a microprocessor, micro-controller, digital signal processor, microcomputer, central processing unit, field programmable gate array, programmable logic device, state machine, logic circuitry, analog circuitry, digital circuitry, and/or any device that manipulates signals (analog and/or digital) based on operational instructions. The memory  66  may be a single memory device or a plurality of memory devices. Such a memory device may be a read-only memory, random access memory, volatile memory, non-volatile memory, static memory, dynamic memory, flash memory, and/or any device that stores digital information. Note that when the processing module  63  implements one or more of its functions via a state machine, analog circuitry, digital circuitry, and/or logic circuitry, the memory storing the corresponding operational instructions is embedded with the circuitry comprising the state machine, analog circuitry, digital circuitry, and/or logic circuitry. 
         [0026]    In operation, the baseband processing module  63  receives the outbound data  87  and, based on a mode selection signal  101 , produces one or more outbound symbol streams  89 . The mode selection signal  101  will indicate a particular mode as are indicated in mode selection tables. For example, the mode selection signal  101  may indicate a frequency band of 2.4 GHz, a channel bandwidth of 20 or 22 MHz and a maximum bit rate of 54 megabits-per-second. In this general category, the mode selection signal will further indicate a particular rate ranging from 1 megabit-per-second to 54 megabits-per-second. In addition, the mode selection signal will indicate a particular type of modulation, which includes, but is not limited to, Barker Code Modulation, BPSK, QPSK, CCK, 16 QAM and/or 64 QAM. A code rate is supplied as well as number of coded bits per subcarrier (NBPSC), coded bits per OFDM symbol (NCBPS), data bits per OFDM symbol (NDBPS), error vector magnitude in decibels (EVM), sensitivity which indicates the maximum receive power required to obtain a target packet error rate (e.g., 10% for IEEE 802.11a), adjacent channel rejection (ACR), and an alternate adjacent channel rejection (AACR). 
         [0027]    The mode selection signal may also indicate a particular channelization for the corresponding mode. The mode select signal may further indicate a power spectral density mask value. The mode select signal may alternatively indicate a rate that has a 5 GHz frequency band, 20 MHz channel bandwidth and a maximum bit rate of 54 megabits-per-second. As a further alternative, the mode select signal  101  may indicate a 2.4 GHz frequency band, 20 MHz channels and a maximum bit rate of 192 megabits-per-second. A number of antennas may be utilized to achieve the higher bandwidths. In this instance, the mode select would further indicate the number of antennas to be utilized. Another mode option may be utilized where the frequency band is 2.4 GHz, the channel bandwidth is 20 MHz and the maximum bit rate is 192 megabits-per-second. Various bit rates ranging from 12 megabits-per-second to 216 megabits-per-second utilizing 2-4 antennas and a spatial time encoding rate may be employed. The mode select signal  101  may further indicate a particular operating mode, which corresponds to a 5 GHz frequency band having 40 MHz frequency band having 40 MHz channels and a maximum bit rate of 486 megabits-per-second. The bit rate may range, in this example, from 13.5 megabits-per-second to 486 megabits-per-second utilizing 1-4 antennas and a corresponding spatial time code rate. 
         [0028]    The baseband processing module  63 , based on the mode selection signal  101  produces the one or more outbound symbol streams  89  from the output data  88 . For example, if the mode selection signal  101  indicates that a single transmit antenna is being utilized for the particular mode that has been selected, the baseband processing module  63  will produce a single outbound symbol stream  89 . Alternatively, if the mode select signal indicates 2, 3 or 4 antennas, the baseband processing module  63  will produce 2, 3 or 4 outbound symbol streams  89  corresponding to the number of antennas from the output data  88 . 
         [0029]    Depending on the number of outbound streams  89  produced by the baseband module  63 , a corresponding number of the RF transmitters  67 ,  69 ,  71  can be enabled to convert the outbound symbol streams  89  into outbound RF signals  91 . The implementation of the RF transmitters  67 ,  69 ,  71  will be further described with reference to  FIG. 2 . The transmit/receive module  73  receives the outbound RP signals  91  and provides each outbound RF signal to a corresponding antenna  81 ,  83 ,  85 . 
         [0030]    When the radio  60  is in the receive mode, the transmit/receive module  73  receives one or more inbound RF signals via the antennas  81 ,  83 ,  85 . The T/R module  73  provides the inbound RF signals  93  to one or more RF receivers  75 ,  77 ,  79 . The RF receiver  75 ,  77 ,  79 , which will be described in greater detail with reference to  FIG. 4 , converts the inbound RF signals  93  into a corresponding number of inbound symbol streams  96 . The number of inbound symbol streams  95  will correspond to the particular mode in which the data was received. The baseband processing module  63  receives the inbound symbol streams  89  and converts them into inbound data  97 . 
         [0031]    As one of average skill in the art will appreciate, the wireless communication device of  FIG. 1  may be implemented using one or more integrated circuits. For example, the device may be implemented on one integrated circuit, the baseband processing module  63  and memory  65  may be implemented on a second integrated circuit, and the remaining components, less the antennas  81 ,  83 ,  85 , may be implemented on a third integrated circuit. As an alternate example, the device may be implemented on a single integrated circuit. 
         [0032]      FIG. 2(   a ) is a schematic block diagram of an embodiment of an RF transmitter  67 ,  69 ,  71 . The RF transmitter may include a digital filter and up-sampling module  475 , a digital-to-analog conversion module  477 , an analog filter  479 , and up-conversion module  81 , a power amplifier  483  and a RF filter  485 . The digital filter and up-sampling module  475  receives one of the outbound symbol streams  89  and digitally filters it and then up-samples the rate of the symbol streams to a desired rate to produce the filtered symbol streams  487 . The digital-to-analog conversion module  477  converts the filtered symbols  487  into analog signals  489 . The analog signals may include an in-phase component and a quadrature component. 
         [0033]    The analog filter  479  filters the analog signals  489  to produce filtered analog signals  491 . The up-conversion module  481 , which may include a pair of mixers and a filter, mixes the filtered analog signals  491  with a local oscillation  493 , which is produced by local oscillation module  99 , to produce high frequency signals  495 . The frequency of the high frequency signals  495  corresponds to the frequency of the RF signals  492 . 
         [0034]    The power amplifier  483  amplifies the high frequency signals  495  to produce amplified high frequency signals  497 . The RF filter  485 , which may be a high frequency band-pass filter, filters the amplified high frequency signals  497  to produce the desired output RF signals  91 . 
         [0035]    As one of average skill in the art will appreciate, each of the radio frequency transmitters  67 ,  69 ,  71  will include a similar architecture as illustrated in  FIG. 2(   a ) and further include a shut-down mechanism such that when the particular radio frequency transmitter is not required, it is disabled in such a manner that it does not produce interfering signals and/or noise. 
         [0036]      FIG. 2(   b ) is a schematic block diagram of each of the RF receivers  75 ,  77 ,  79 . In this embodiment, each of the RF receivers may include an RF filter  501 , a low noise amplifier (LNA)  503 , a programmable gain amplifier (PGA)  505 , a down-conversion module  507 , an analog filter  509 , an analog-to-digital conversion module  511  and a digital filter and down-sampling module  513 . The RF filter  501 , which may be a high frequency band-pass filter, receives the inbound RF signals  93  and filters them to produce filtered inbound RF signals. The low noise amplifier  503  amplifies the filtered inbound RF signals  93  based on a gain setting and provides the amplified signals to the programmable gain amplifier  505 . The programmable gain amplifier further amplifies the inbound RF signals  93  before providing them to the down-conversion module  507 . 
         [0037]    The down-conversion module  507  includes a pair of mixers, a summation module, and a filter to mix the inbound RF signals with a local oscillation (LO) that is provided by the local oscillation module to produce analog baseband signals. The analog filter  509  filters the analog baseband signals and provides them to the analog-to-digital conversion module  511  which converts them into a digital signal. The digital filter and down-sampling module  513  filters the digital signals and then adjusts the sampling rate to produce the inbound symbol stream  95 . 
         [0038]      FIGS. 3(   a ) and  3 ( b ) illustrate a schematic block diagram of a multiple transmitter in accordance with the present invention. In  FIG. 3(   a ), the baseband processing is shown to include a scrambler  172 , channel encoder  174 , interleaver  176 , demultiplexer  170 , a plurality of symbol mappers  180 - 1  through  180 - m , a space/time encoder  190  and a plurality of inverse fast Fourier transform (IFFT)/cyclic prefix addition modules  192 - 1  through  192 - m . The baseband portion of the transmitter may further include a mode manager module  175  that receives the mode selection signal and produces settings for the radio transmitter portion and produces the rate selection for the baseband portion. 
         [0039]    In operations, the scrambler  172  adds (in GF2) a pseudo random sequence to the outbound data bits  88  to make the data appear random. A pseudo random sequence may be generated from a feedback shift register with the generator polynomial, for example, of S(x)=x 7 +x 4 +1 to produce scrambled data. The channel encoder  174  receives the scrambled data and generates a new sequence of bits with redundancy. This will enable improved detection at the receiver. The channel encoder  174  may operate in one of a plurality of modes. For example, for backward compatibility with standards such as IEEE 802.11(a) and IEEE 802.11(g), the channel encoder has the form of a rate ½ convolutional encoder with 64 states and a generator polynomials of G 0 =133 8  and G 1 =171 8 . The output of the convolutional encoder may be punctured to rates of ½, ⅔rds and ¾ according to the specified rate tables. For backward compatibility with IEEE 802.11(b) and the CCK modes of IEEE 802.11(g), the channel encoder has the form of a CCK code as defined in IEEE 802.11(b). For higher data rates, the channel encoder may use the same convolution encoding as described above or it may use a more powerful code, including a convolutional code with more states, a parallel concatenated (turbo) code and/or a low density parity check (LDPC) block code. Further, any one of these codes may be combined with an outer Reed Solomon code. Based on a balancing of performance, backward compatibility and low latency, one or more of these codes may be optimal. 
         [0040]    The interleaver  176  receives the encoded data and spreads it over multiple symbols and transmit streams. This allows improved detection and error correction capabilities at the receiver. In one embodiment, the interleaver  176  will follow the IEEE 802.11(a) or (g) standard in the backward compatible modes. For higher performance modes, the interleaver will interleave data over multiple transmit streams. The demultiplexer  170  converts the serial interleave stream from interleaver  176  into M-parallel streams for transmission. 
         [0041]    Each symbol mapper  180 - m  through  180 - m  receives a corresponding one of the M-parallel paths of data from the demultiplexer. Each symbol mapper locks maps bit streams to quadrature amplitude modulated QAM symbols (e.g., BPSK, QPSK, 16 QAM, 64 QAM, 256 QAM, et cetera) according to the rate tables. For IEEE 802.11 (a) backward compatibility, double gray coding may be used. 
         [0042]    The map symbols produced by each of the symbol mappers  180  are provided to the space/time encoder  190 . Thereafter, output symbols are provided to the IFFT/cyclic prefix addition modules  192 - 1  through  192 - m , which performs frequency domain to time domain conversions and adds a prefix, which allows removal of inter-symbol interference at the receiver. In general, a 64-point IFFT will be used for 20 MHz channels and 128-point IFFT will be used for 40 MHz channels. 
         [0043]    In one embodiment, the number of M-input paths will equal the number of P-output paths. In another embodiment, the number of output paths P will equal M+1 paths. For each of the paths, the space/time encoder multiples the input symbols with an encoding matrix that has the form of: 
         [0000]    
       
         
           
               
             
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         [0000]    Note that the rows of the encoding matrix correspond to the number of input paths and the columns correspond to the number of output paths. 
         [0044]      FIG. 3(   b ) illustrates the radio portion of the transmitter that includes a plurality of digital filter/up-sampling modules  195 - 1  through  195 - m , digital-to-analog conversion modules  200 - 1  through  200 - m , analog filters  210 - 1  through  210 - m  and  215 - 1  through  215 - m , I/Q modulators  220 - 1  through  220 - m , RF amplifiers  225 - 1  through  225 - m , RF filters  230 - 1  through  230 - m  and antennas  240 - 1  through  240 - m . The P-outputs from the other stage are received by respective digital filtering/up-sampling modules  195 - 1  through  195 - m.    
         [0045]    In operation, the number of radio paths that are active correspond to the number of P-outputs. For example, if only one P-output path is generated, only one of the radio transmitter paths will be active. As one of average skill in the art will appreciate, the number of output paths may range from one to any desired number. 
         [0046]    The digital filtering/up-sampling modules  195 - 1  through  195 - m  filter the corresponding symbols and adjust the sampling rates to correspond with the desired sampling rates of the digital-to-analog conversion modules  200 . The digital-to-analog conversion modules  200  convert the digital filtered and up-sampled signals into corresponding in-phase and quadrature analog signals. The analog filters  210  and  215  filter the corresponding in-phase and/or quadrature components of the analog signals, and provide the filtered signals to the corresponding I/Q modulators  220 . The I/Q modulators  220  based on a local oscillation, which is produced by a local oscillator  100 , up-converts the I/Q signals into radio frequency signals. The RF amplifiers  225  amplify the RF signals which are then subsequently filtered via RF filters  230  before being transmitted via antennas  240 . 
         [0047]      FIGS. 4(   a ) and  4 ( b ) illustrate a schematic block diagram of another embodiment of a receiver in accordance with the present invention.  FIG. 4(   a ) illustrates the analog portion of the receiver which includes a plurality of receiver paths. Each receiver path includes an antenna  250 - 1  through  250 - n , RF filters  255 - 1  through  255 - n , low noise amplifiers  260 - 1  through  260 - n , I/O demodulators  265 - 1  through  265 - n , analog filters  270 - 1  through  270 - n  and  275 - 1  through  275 - n , analog-to-digital converters  280 - 1  through  280 - n  and digital filters and down-sampling modules  290 - 1  through  290 - n.    
         [0048]    In operation, the antennas  250  receive inbound RF signals, which are band-pass filtered via the RF filters  255 . The corresponding low noise amplifiers  260  amplify the filtered signals and provide them to the corresponding I/Q demodulators  265 . The I/Q demodulators  265 , based on a local oscillation, which is produced by local oscillator  100 , down-converts the RF signals into baseband in-phase and quadrature analog signals. 
         [0049]    The corresponding analog filters  270  and  275  filter the in-phase and quadrature analog components, respectively. The analog-to-digital converters  280  convert the in-phase and quadrature analog signals into a digital signal. The digital filtering and down-sampling modules  290  filter the digital signals and adjust the sampling rate to correspond to the rate of the baseband processing, which will be described in  FIG. 4(   b ). 
         [0050]      FIG. 4(   b ) illustrates the baseband processing of a receiver. The baseband processing portion includes a plurality of fast Fourier transform (FFT)/cyclic prefix removal modules  294 - 1  through  294 - n , a space/time decoder  296 , a plurality of symbol demapping modules  300 - 1  through  300 - n , a multiplexer  310 , a deinterleaver  312 , a channel decoder  314 , and a descramble module  316 . The baseband processing module may further include a mode managing module  175 . The receiver paths are processed via the FFT/cyclic prefix removal modules  294  which perform the inverse function of the IFFT/cyclic prefix addition modules  192  to produce frequency domain symbols as M-output paths. The space/time decoding module  296 , which performs the inverse function of space/time encoder  190 , receives the M-output paths. 
         [0051]    The symbol demapping modules  300  convert the frequency domain symbols into data utilizing an inverse process of the symbol mappers  180 . The multiplexer  310  combines the demapped symbol streams into a single path. 
         [0052]    The deinterleaver  312  deinterleaves the single path utilizing an inverse function of the function performed by interleaver  176 . The deinterleaved data is then provided to the channel decoder  314  which performs the inverse function of channel encoder  174 . The descrambler  316  receives the decoded data and performs the inverse function of scrambler  172  to produce the inbound data  98 . 
         [0053]    As noted above, STBC is usually performed with pairs of antennas, utilizing Orthogonal Frequency Division Multiplexing (OFDM). With multiple antennas, i.e. with more than two antennas, multiple streams can be utilized to achieve higher data rates. In such cases, STBC is applied over some of the transmit antennas, but other antennas transmit signals without STBC. These other antennas may transmit using Spatial Division Multiplexing (SDM). Thus, portions of the signal streams have diversity gains, while others do not. In this way, it is also possible to have greater coding gains from better signal streams. Given these additional possibilities, a receiver according to the present invention should have the ability to detect and separate signals to achieve these gains. 
         [0054]      FIG. 5  is a basic diagram illustrating one embodiment of STBC realization or transmission with SDM by the receiver  521 . Multiple signals, c 1 (t), c 2 (t) and c 3 (t), are received from an encoding block. The t i  denotes an encoding interval index in time, usually a two symbol period for the STBC encoder. After coding, c 1  and c 2  are transmitted through transmission antennas  510   a  and  510   b , and signal c 3  is transmitted through transmission antenna  515   a . The signals c 1  and c 2  can be configured with conjugate values and signal c 3  is encoded by repetition coding. The transmitted signals are received by the STBC decoding block  521 , through receive antennas  520   a  and  520   b . After processing, signals, c 1 , c 2 , and c 3 , based on the originally transmitted signals are reformulated and output through outputs  551 ,  552  and  553 . In general, the received signals are related to the source signals through an “H” or “G” component plus a noise term. 
         [0055]    From this set-up, the channels may be estimated as: 
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                                   2 
                                 
                                  
                                 
                                   ( 
                                   
                                     t 
                                     0 
                                   
                                   ) 
                                 
                               
                             
                           
                         
                         ] 
                       
                     
                     , 
                     
                       
                         c 
                         2 
                       
                       = 
                       
                         [ 
                         
                           
                             c 
                             3 
                           
                            
                           
                             ( 
                             
                               t 
                               0 
                             
                             ) 
                           
                         
                         ] 
                       
                     
                     , 
                     
                       
                         r 
                         1 
                       
                       = 
                       
                         [ 
                         
                           
                             
                               
                                 
                                   r 
                                   1 
                                 
                                  
                                 
                                   ( 
                                   
                                     t 
                                     0 
                                   
                                   ) 
                                 
                               
                             
                           
                           
                             
                               
                                 
                                   r 
                                   1 
                                   ⋆ 
                                 
                                  
                                 
                                   ( 
                                   
                                     t 
                                     1 
                                   
                                   ) 
                                 
                               
                             
                           
                         
                         ] 
                       
                     
                     , 
                     
                       
                         r 
                         2 
                       
                       = 
                       
                         [ 
                         
                           
                             
                               
                                 
                                   r 
                                   2 
                                 
                                  
                                 
                                   ( 
                                   
                                     t 
                                     0 
                                   
                                   ) 
                                 
                               
                             
                           
                           
                             
                               
                                 
                                   r 
                                   2 
                                   ⋆ 
                                 
                                  
                                 
                                   ( 
                                   
                                     t 
                                     1 
                                   
                                   ) 
                                 
                               
                             
                           
                         
                         ] 
                       
                     
                     , 
                     
                       
 
                     
                      
                     
                       
                         H 
                         i 
                       
                       = 
                       
                         [ 
                         
                           
                             
                               
                                 h 
                                 
                                   1 
                                    
                                   i 
                                 
                               
                             
                             
                               
                                 h 
                                 
                                   2 
                                    
                                   
                                       
                                   
                                    
                                   i 
                                 
                               
                             
                           
                           
                             
                               
                                 h 
                                 
                                   2 
                                    
                                   
                                       
                                   
                                    
                                   i 
                                 
                                 ⋆ 
                               
                             
                             
                               
                                 - 
                                 
                                   h 
                                   
                                     1 
                                      
                                     i 
                                   
                                   ⋆ 
                                 
                               
                             
                           
                         
                         ] 
                       
                     
                     , 
                     
                       
                         G 
                         i 
                       
                       = 
                       
                         [ 
                         
                           
                             
                               
                                 g 
                                 i 
                               
                             
                           
                           
                             
                               
                                 g 
                                 i 
                                 ⋆ 
                               
                             
                           
                         
                         ] 
                       
                     
                   
                 
               
               
                 
                   ( 
                   1 
                   ) 
                 
               
             
           
         
       
     
         [0056]    To cancel the interference, zero forcing is applied such that: 
         [0000]    
       
         
           
             
               
                 
                   
                     
                       
                         
                           [ 
                           
                             
                               
                                 
                                   [ 
                                   
                                     
                                       
                                         1 
                                       
                                       
                                         0 
                                       
                                     
                                     
                                       
                                         0 
                                       
                                       
                                         1 
                                       
                                     
                                   
                                   ] 
                                 
                               
                               
                                 
                                   [ 
                                   
                                     
                                       
                                         
                                           
                                             - 
                                             
                                               g 
                                               1 
                                             
                                           
                                            
                                           
                                             g 
                                             2 
                                             
                                               - 
                                               1 
                                             
                                           
                                         
                                       
                                       
                                         0 
                                       
                                     
                                     
                                       
                                         0 
                                       
                                       
                                         
                                           
                                             - 
                                             
                                               g 
                                               1 
                                             
                                           
                                           ⋆ 
                                           
                                             g 
                                             2 
                                             
                                               - 
                                               
                                                 1 
                                                 ⋆ 
                                               
                                             
                                           
                                         
                                       
                                     
                                   
                                   ] 
                                 
                               
                             
                             
                               
                                 
                                   
                                       
                                   
                                    
                                   
                                     
                                       z 
                                       1 
                                     
                                      
                                     
                                         
                                     
                                      
                                     
                                       z 
                                       2 
                                     
                                   
                                 
                               
                               
                                 
                                   
                                     z 
                                     3 
                                   
                                    
                                   
                                       
                                   
                                    
                                   
                                     z 
                                     4 
                                   
                                 
                               
                             
                           
                           ] 
                         
                         
                           3 
                           × 
                           4 
                         
                       
                       × 
                       
                         [ 
                         
                             
                         
                          
                         
                           
                             
                               
                                 r 
                                 1 
                               
                             
                           
                           
                             
                               
                                 r 
                                 2 
                               
                             
                           
                         
                         ] 
                       
                     
                     = 
                     
                       
                         [ 
                         
                             
                         
                          
                         
                           
                             
                               
                                 
                                   r 
                                   ~ 
                                 
                                 1 
                               
                             
                           
                           
                             
                               
                                 
                                   r 
                                   ~ 
                                 
                                 2 
                               
                             
                           
                         
                         ] 
                       
                       = 
                       
                         
                           
                             
                               [ 
                               
                                 
                                   
                                     
                                       H 
                                       ~ 
                                     
                                   
                                   
                                     0 
                                   
                                 
                                 
                                   
                                     0 
                                   
                                   
                                     
                                       G 
                                       ~ 
                                     
                                   
                                 
                               
                               ] 
                             
                             
                               3 
                               × 
                               3 
                             
                           
                           × 
                           
                             [ 
                             
                               
                                 
                                   
                                     c 
                                     1 
                                   
                                 
                               
                               
                                 
                                   
                                     c 
                                     2 
                                   
                                 
                               
                             
                             ] 
                           
                         
                         + 
                         
                           [ 
                           
                             
                               
                                 
                                   
                                     n 
                                     ~ 
                                   
                                   1 
                                 
                               
                             
                             
                               
                                 
                                   
                                     n 
                                     ~ 
                                   
                                   2 
                                 
                               
                             
                           
                           ] 
                         
                       
                     
                   
                    
                   
                     
 
                   
                    
                   
                     where 
                     , 
                     
                       
                         
                           H 
                           ~ 
                         
                         
                           2 
                           × 
                           2 
                         
                       
                       = 
                       
                         
                           H 
                           1 
                         
                         - 
                         
                           
                             [ 
                             
                               
                                 
                                   
                                     
                                       - 
                                       
                                         g 
                                         1 
                                       
                                     
                                      
                                     
                                       g 
                                       2 
                                       
                                         - 
                                         1 
                                       
                                     
                                   
                                 
                                 
                                   0 
                                 
                               
                               
                                 
                                   0 
                                 
                                 
                                   
                                     
                                       - 
                                       
                                         g 
                                         1 
                                       
                                     
                                     ⋆ 
                                     
                                       g 
                                       2 
                                       
                                         - 
                                         
                                           1 
                                           ⋆ 
                                         
                                       
                                     
                                   
                                 
                               
                             
                             ] 
                           
                           × 
                           
                             H 
                             2 
                           
                         
                       
                     
                     , 
                     
                       
 
                     
                      
                     
                       
                         
                           G 
                           ~ 
                         
                         
                           1 
                           × 
                           1 
                         
                       
                       = 
                       
                         
                           
                             
                                
                               
                                 g 
                                 1 
                               
                                
                             
                             2 
                           
                           + 
                           
                             
                                
                               
                                 g 
                                 2 
                               
                                
                             
                             2 
                           
                         
                       
                     
                     , 
                   
                 
               
               
                 
                   ( 
                   2 
                   ) 
                 
               
             
           
         
       
     
         [0057]    and z 1 , z 2 , z 3  and z 4  satisfy the following equation: 
         [0000]        h   11   z   1   +h   21   *z   2   +h   12   z   3   +h   22   *z   4 =0 
         [0000]        h   21   z   1   −h   11   *z   2   +h   22   z   3   −h   12   *z   4 =0 
         [0000]        g   1   z   1   +g   1   *z   2   +g   2   z   3   +g   2   *z   4 =√{square root over (| g   1 | 2   +|g   2 | 2 )}  (3) 
         [0058]    Thereafter Z is found by zero-forcing to minimize noise enhancement, such that: 
         [0000]    
       
         
           
             
               
                 
                   z 
                   = 
                   
                     
                       
                         ( 
                         
                           AA 
                           ⋆ 
                         
                         ) 
                       
                       
                         - 
                         1 
                       
                     
                      
                     
                       A 
                       ⋆ 
                     
                      
                     c 
                   
                 
               
               
                 
                   ( 
                   4 
                   ) 
                 
               
             
             
               
                 
                   where 
                   , 
                   
                     z 
                     = 
                     
                       
                         [ 
                         
                           
                             
                               
                                 z 
                                 1 
                               
                             
                             
                               
                                 z 
                                 2 
                               
                             
                             
                               
                                 z 
                                 3 
                               
                             
                             
                               
                                 z 
                                 4 
                               
                             
                           
                         
                         ] 
                       
                       ′ 
                     
                   
                   , 
                   
                     
 
                   
                    
                   
                     A 
                     = 
                     
                       [ 
                       
                         
                           
                             
                               h 
                               11 
                             
                           
                           
                             
                               h 
                               21 
                               ⋆ 
                             
                           
                           
                             
                               h 
                               12 
                             
                           
                           
                             
                               h 
                               22 
                               ⋆ 
                             
                           
                         
                         
                           
                             
                               h 
                               22 
                             
                           
                           
                             
                               - 
                               
                                 h 
                                 11 
                                 ⋆ 
                               
                             
                           
                           
                             
                               h 
                               22 
                             
                           
                           
                             
                               - 
                               
                                 h 
                                 12 
                                 ⋆ 
                               
                             
                           
                         
                         
                           
                             
                               g 
                               1 
                             
                           
                           
                             
                               g 
                               1 
                               ⋆ 
                             
                           
                           
                             
                               g 
                               2 
                             
                           
                           
                             
                               g 
                               2 
                               ⋆ 
                             
                           
                         
                       
                       ] 
                     
                   
                   , 
                   
                     
 
                   
                    
                   
                     c 
                     = 
                     
                       
                         
                           [ 
                           
                             
                               
                                 0 
                               
                               
                                 0 
                               
                               
                                 
                                   
                                     
                                       
                                          
                                         
                                           g 
                                           1 
                                         
                                          
                                       
                                       2 
                                     
                                     + 
                                     
                                       
                                          
                                         
                                           g 
                                           2 
                                         
                                          
                                       
                                       2 
                                     
                                   
                                 
                               
                             
                           
                           ] 
                         
                         ′ 
                       
                       . 
                     
                   
                 
               
               
                 
                     
                 
               
             
           
         
       
     
         [0059]    Next, STBC decoding may be performed with channel matching such that 
         [0000]    
       
         
           
             
               
                 
                   
                     
                       
                         [ 
                         
                           
                             
                               
                                 
                                   H 
                                   ~ 
                                 
                                 ⋆ 
                               
                             
                             
                               
                                   
                               
                             
                             
                               0 
                             
                           
                           
                             
                               
                                   
                               
                             
                             
                               
                                   
                               
                             
                             
                               0 
                             
                           
                           
                             
                               0 
                             
                             
                               0 
                             
                             
                               
                                 
                                   G 
                                   ~ 
                                 
                                 ⋆ 
                               
                             
                           
                         
                         ] 
                       
                        
                       
                         [ 
                         
                           
                             
                               
                                 
                                   r 
                                   ~ 
                                 
                                 1 
                               
                             
                           
                           
                             
                               
                                 
                                   r 
                                   ~ 
                                 
                                 2 
                               
                             
                           
                         
                         ] 
                       
                     
                     = 
                     
                       
                         
                           [ 
                           
                             
                               
                                 
                                   
                                     
                                       H 
                                       ~ 
                                     
                                     ⋆ 
                                   
                                    
                                   
                                     H 
                                     ~ 
                                   
                                 
                               
                               
                                 
                                     
                                 
                               
                               
                                 0 
                               
                             
                             
                               
                                 
                                     
                                 
                               
                               
                                 
                                     
                                 
                               
                               
                                 0 
                               
                             
                             
                               
                                 0 
                               
                               
                                 0 
                               
                               
                                 
                                   
                                     
                                       G 
                                       ~ 
                                     
                                     ⋆ 
                                   
                                    
                                   
                                     G 
                                     ~ 
                                   
                                 
                               
                             
                           
                           ] 
                         
                          
                         
                           [ 
                           
                             
                               
                                 
                                   c 
                                   1 
                                 
                               
                             
                             
                               
                                 
                                   c 
                                   2 
                                 
                               
                             
                           
                           ] 
                         
                       
                       + 
                       
                         [ 
                         
                           
                             
                               
                                 N 
                                 1 
                               
                             
                           
                           
                             
                               
                                 N 
                                 2 
                               
                             
                           
                         
                         ] 
                       
                     
                   
                    
                   
                       
                   
                    
                   
                     
 
                   
                    
                   
                     where 
                     , 
                     
                       
 
                     
                      
                     
                       
                         
                           
                             H 
                             ~ 
                           
                           ⋆ 
                         
                          
                         
                           H 
                           ~ 
                         
                       
                       = 
                       
                         
                           
                             ( 
                             
                               
                                 H 
                                 1 
                               
                               - 
                               
                                 
                                   [ 
                                   
                                     
                                       
                                         
                                           
                                             - 
                                             
                                               g 
                                               1 
                                             
                                           
                                            
                                           
                                             g 
                                             2 
                                             
                                               - 
                                               1 
                                             
                                           
                                         
                                       
                                       
                                         0 
                                       
                                     
                                     
                                       
                                         0 
                                       
                                       
                                         
                                           
                                             - 
                                             
                                               g 
                                               1 
                                             
                                           
                                           ⋆ 
                                           
                                             g 
                                             2 
                                             
                                               - 
                                               
                                                 1 
                                                 ⋆ 
                                               
                                             
                                           
                                         
                                       
                                     
                                   
                                   ] 
                                 
                                 × 
                                 
                                   H 
                                   2 
                                 
                               
                             
                             ) 
                           
                           ⋆ 
                         
                          
                         
                           ( 
                           
                             
                               H 
                               1 
                             
                             - 
                             
                               
                                 [ 
                                 
                                   
                                     
                                       
                                         
                                           - 
                                           
                                             g 
                                             1 
                                           
                                         
                                          
                                         
                                           g 
                                           2 
                                           
                                             - 
                                             1 
                                           
                                         
                                       
                                     
                                     
                                       0 
                                     
                                   
                                   
                                     
                                       0 
                                     
                                     
                                       
                                         
                                           - 
                                           
                                             g 
                                             1 
                                           
                                         
                                         ⋆ 
                                         
                                           g 
                                           2 
                                           
                                             - 
                                             
                                               1 
                                               ⋆ 
                                             
                                           
                                         
                                       
                                     
                                   
                                 
                                 ] 
                               
                               × 
                               
                                 H 
                                 2 
                               
                             
                           
                           ) 
                         
                       
                     
                     , 
                     
                         
                     
                      
                     
                       
 
                     
                      
                     
                         
                     
                      
                     
                       
                         
                           
                             G 
                             ~ 
                           
                           ⋆ 
                         
                          
                         
                           G 
                           ~ 
                         
                       
                       = 
                       
                         
                           
                              
                             
                               g 
                               1 
                             
                              
                           
                           2 
                         
                         + 
                         
                           
                              
                             
                               g 
                               2 
                             
                              
                           
                           2 
                         
                       
                     
                     , 
                   
                 
               
               
                 
                   ( 
                   5 
                   ) 
                 
               
             
           
         
       
     
         [0060]    which is diagonalized and constant x identity. 
         [0061]      FIG. 6  is a basic diagram illustrating another embodiment of STBC realization or transmission with SDM by the receiver  621 . Multiple signals, c 1 (t), c 2 (t), c 3 (t) and c 4 (t), are received from an encoding block. After coding, c 1  and c 2  are transmitted through transmission antennas  610   a  and  610   b , and signals c 3  and c 4  are transmitted through transmission antenna  615   a . The signals c 1  and c 2  can be configured with conjugate values and signals c 3  and c 4  are being transmitted as in SDM with conjugate. The transmitted signals are received by the STBC decoding block  621 , through receive antennas  620   a  and  620   b . After processing, signals, c 1 , c 2 , c 3  and c 4 , based on the originally transmitted signals are reformulated and output through outputs  651 - 654 . In general, the received signals are related to the source signals through an “H” or “G” component plus a noise term. 
         [0062]    From this set-up, the channels may be estimated as: 
         [0000]    
       
         
           
             
               
                 
                   
                     
                       
                         [ 
                         
                           
                             
                               
                                 r 
                                 1 
                               
                             
                           
                           
                             
                               
                                 r 
                                 2 
                               
                             
                           
                         
                         ] 
                       
                       
                         4 
                         × 
                         1 
                       
                     
                     = 
                     
                       
                         
                           
                             
                               [ 
                               
                                 
                                   
                                     
                                       H 
                                       1 
                                     
                                   
                                   
                                     
                                       G 
                                       1 
                                     
                                   
                                 
                                 
                                   
                                     
                                       H 
                                       2 
                                     
                                   
                                   
                                     
                                       G 
                                       2 
                                     
                                   
                                 
                               
                               ] 
                             
                             
                               4 
                               × 
                               4 
                             
                           
                            
                           
                             [ 
                             
                               
                                 
                                   
                                     c 
                                     1 
                                   
                                 
                               
                               
                                 
                                   
                                     c 
                                     2 
                                   
                                 
                               
                             
                             ] 
                           
                         
                         
                           4 
                           × 
                           1 
                         
                       
                       + 
                       
                         
                           [ 
                           
                             
                               
                                 
                                   n 
                                   1 
                                 
                               
                             
                             
                               
                                 
                                   n 
                                   2 
                                 
                               
                             
                           
                           ] 
                         
                         
                           4 
                           × 
                           1 
                         
                       
                     
                   
                    
                   
                       
                   
                    
                   
                     
 
                   
                    
                   
                     where 
                     , 
                     
                       
 
                     
                      
                     
                       
                         c 
                         1 
                       
                       = 
                       
                         [ 
                         
                           
                             
                               
                                 
                                   c 
                                   1 
                                 
                                  
                                 
                                   ( 
                                   
                                     t 
                                     0 
                                   
                                   ) 
                                 
                               
                             
                           
                           
                             
                               
                                 
                                   c 
                                   2 
                                 
                                  
                                 
                                   ( 
                                   
                                     t 
                                     0 
                                   
                                   ) 
                                 
                               
                             
                           
                         
                         ] 
                       
                     
                     , 
                     
                       
                         c 
                         2 
                       
                       = 
                       
                         [ 
                         
                           
                             
                               
                                 
                                   c 
                                   3 
                                 
                                  
                                 
                                   ( 
                                   
                                     t 
                                     0 
                                   
                                   ) 
                                 
                               
                             
                           
                           
                             
                               
                                 
                                   c 
                                   4 
                                 
                                  
                                 
                                   ( 
                                   
                                     t 
                                     0 
                                   
                                   ) 
                                 
                               
                             
                           
                         
                         ] 
                       
                     
                     , 
                     
                       
                         r 
                         1 
                       
                       = 
                       
                         [ 
                         
                           
                             
                               
                                 
                                   r 
                                   1 
                                 
                                  
                                 
                                   ( 
                                   
                                     t 
                                     0 
                                   
                                   ) 
                                 
                               
                             
                           
                           
                             
                               
                                 
                                   r 
                                   1 
                                   ⋆ 
                                 
                                  
                                 
                                   ( 
                                   
                                     t 
                                     1 
                                   
                                   ) 
                                 
                               
                             
                           
                         
                         ] 
                       
                     
                     , 
                     
                       
                         r 
                         2 
                       
                       = 
                       
                         [ 
                         
                           
                             
                               
                                 
                                   r 
                                   2 
                                 
                                  
                                 
                                   ( 
                                   
                                     t 
                                     0 
                                   
                                   ) 
                                 
                               
                             
                           
                           
                             
                               
                                 
                                   r 
                                   2 
                                   ⋆ 
                                 
                                  
                                 
                                   ( 
                                   
                                     t 
                                     1 
                                   
                                   ) 
                                 
                               
                             
                           
                         
                         ] 
                       
                     
                     , 
                     
                       
 
                     
                      
                     
                       
                         H 
                         i 
                       
                       = 
                       
                         [ 
                         
                           
                             
                               
                                 h 
                                 
                                   1 
                                    
                                   i 
                                 
                               
                             
                             
                               
                                 h 
                                 
                                   2 
                                    
                                   
                                       
                                   
                                    
                                   i 
                                 
                               
                             
                           
                           
                             
                               
                                 h 
                                 
                                   2 
                                    
                                   
                                       
                                   
                                    
                                   i 
                                 
                                 ⋆ 
                               
                             
                             
                               
                                 - 
                                 
                                   h 
                                   
                                     1 
                                      
                                     i 
                                   
                                   ⋆ 
                                 
                               
                             
                           
                         
                         ] 
                       
                     
                     , 
                     
                       
                         G 
                         i 
                       
                       = 
                       
                         [ 
                         
                           
                             
                               
                                 
                                   g 
                                   i 
                                 
                               
                             
                             
                               
                                 0 
                               
                             
                           
                            
                           
                             
                               
                                 0 
                               
                             
                             
                               
                                 
                                   g 
                                   i 
                                   ⋆ 
                                 
                               
                             
                           
                         
                         ] 
                       
                     
                   
                 
               
               
                 
                   ( 
                   6 
                   ) 
                 
               
             
           
         
       
     
         [0063]    To cancel the interference, zero forcing is applied such that: 
         [0000]    
       
         
           
             
               
                 
                   
                     
                       [ 
                       
                         
                           
                             
                               [ 
                               
                                 
                                   
                                     1 
                                   
                                   
                                     0 
                                   
                                 
                                 
                                   
                                     0 
                                   
                                   
                                     1 
                                   
                                 
                               
                               ] 
                             
                           
                           
                             
                               [ 
                               
                                 
                                   
                                     
                                       
                                         - 
                                         
                                           g 
                                           1 
                                         
                                       
                                        
                                       
                                         g 
                                         2 
                                         
                                           - 
                                           1 
                                         
                                       
                                     
                                   
                                   
                                     0 
                                   
                                 
                                 
                                   
                                     0 
                                   
                                   
                                     
                                       
                                         - 
                                         
                                           g 
                                           1 
                                         
                                       
                                       ⋆ 
                                       
                                         g 
                                         2 
                                         
                                           - 
                                           
                                             1 
                                             ⋆ 
                                           
                                         
                                       
                                     
                                   
                                 
                               
                               ] 
                             
                           
                         
                         
                           
                             
                               
                                   
                               
                                
                               
                                 
                                   z 
                                   11 
                                 
                                  
                                 
                                     
                                 
                                  
                                 
                                   z 
                                   12 
                                 
                               
                             
                           
                           
                             
                               
                                 z 
                                 13 
                               
                                
                               
                                   
                               
                                
                               
                                 z 
                                 14 
                               
                             
                           
                         
                         
                           
                             
                               
                                   
                               
                                
                               
                                 
                                   z 
                                   
                                     21 
                                      
                                     
                                         
                                     
                                   
                                 
                                  
                                 
                                   z 
                                   22 
                                 
                               
                             
                           
                           
                             
                               
                                 z 
                                 
                                   23 
                                    
                                   
                                       
                                   
                                 
                               
                                
                               
                                 z 
                                 24 
                               
                             
                           
                         
                       
                       ] 
                     
                     × 
                     
                         
                     
                      
                     
                       [ 
                       
                         
                           
                             
                               r 
                               1 
                             
                           
                         
                         
                           
                             
                               r 
                               2 
                             
                           
                         
                       
                       ] 
                     
                   
                   = 
                   
                       
                     
                       
                         
                           [ 
                           
                             
                               
                                 
                                   
                                     r 
                                     ~ 
                                   
                                   1 
                                 
                               
                             
                             
                               
                                 
                                   
                                     r 
                                     ~ 
                                   
                                   2 
                                 
                               
                             
                           
                           ] 
                         
                         = 
                         
                           
                             
                               
                                 [ 
                                 
                                   
                                     
                                       
                                         H 
                                         ~ 
                                       
                                     
                                     
                                       0 
                                     
                                   
                                   
                                     
                                       0 
                                     
                                     
                                       
                                         G 
                                         ~ 
                                       
                                     
                                   
                                 
                                 ] 
                               
                               
                                 4 
                                 × 
                                 4 
                               
                             
                             × 
                             
                               [ 
                               
                                 
                                   
                                     
                                       c 
                                       1 
                                     
                                   
                                 
                                 
                                   
                                     
                                       c 
                                       2 
                                     
                                   
                                 
                               
                               ] 
                             
                           
                           + 
                           
                             
                               [ 
                               
                                 
                                   
                                     
                                       
                                         n 
                                         ~ 
                                       
                                       1 
                                     
                                   
                                 
                                 
                                   
                                     
                                       
                                         n 
                                         ~ 
                                       
                                       2 
                                     
                                   
                                 
                               
                               ] 
                             
                              
                             
                               
 
                             
                              
                             where 
                           
                         
                       
                       , 
                       
                         
                           
                             H 
                             ~ 
                           
                           
                             2 
                             × 
                             2 
                           
                         
                         = 
                         
                           
                             H 
                             1 
                           
                           - 
                           
                             
                               [ 
                               
                                 
                                   
                                     
                                       
                                         - 
                                         
                                           g 
                                           1 
                                         
                                       
                                        
                                       
                                         g 
                                         2 
                                         
                                           - 
                                           1 
                                         
                                       
                                     
                                   
                                   
                                     0 
                                   
                                 
                                 
                                   
                                     0 
                                   
                                   
                                     
                                       
                                         - 
                                         
                                           g 
                                           1 
                                         
                                       
                                       ⋆ 
                                       
                                         g 
                                         2 
                                         
                                           - 
                                           
                                             1 
                                             ⋆ 
                                           
                                         
                                       
                                     
                                   
                                 
                               
                               ] 
                             
                             × 
                             
                               H 
                               2 
                             
                           
                         
                       
                       , 
                       
                         
 
                       
                        
                       
                         
                           
                             G 
                             ~ 
                           
                           
                             2 
                             × 
                             2 
                           
                         
                         = 
                         
                           
                             
                               
                                 
                                    
                                   
                                     g 
                                     1 
                                   
                                    
                                 
                                 2 
                               
                               + 
                               
                                 
                                    
                                   
                                     g 
                                     2 
                                   
                                    
                                 
                                 2 
                               
                             
                           
                           × 
                           
                             [ 
                             
                               
                                 
                                   1 
                                 
                                 
                                   0 
                                 
                               
                               
                                 
                                   0 
                                 
                                 
                                   1 
                                 
                               
                             
                             ] 
                           
                         
                       
                       , 
                     
                      
                     
                         
                     
                   
                 
               
               
                 
                   ( 
                   7 
                   ) 
                 
               
             
           
         
       
     
         [0064]    and z ij  satisfy the following equation: 
         [0000]        h   11   z   i1   +h   21   *z   i2   +h   12   z   i3   +h   22   *z   i4 =0 
         [0000]        h   21   z   i1   −h   11   *z   i2   +h   22   z   i3   −h   12   *z   i4 =0 
         [0000]        g   1   z   11   +g   2   z   13 =√{square root over (| g   1 | 2   +|g   2 | 2 )} 
         [0000]        g   1   *z   22   +g   2   *z   24 =√{square root over (| g   1 | 2   +|g   2 | 2 )}  (8) 
         [0065]    with i being 1 or 2 in the above series of equations. 
         [0066]    Thereafter Z is found by zero-forcing to minimize noise enhancement, such that: 
         [0000]    
       
         
           
             
               
                 
                   
                     z 
                     = 
                     
                       
                         
                           ( 
                           
                             AA 
                             * 
                           
                           ) 
                         
                         
                           - 
                           1 
                         
                       
                        
                       
                         A 
                         * 
                       
                        
                       c 
                     
                   
                    
                   
                     
 
                   
                    
                   
                     
                       z 
                       = 
                       
                         
                           [ 
                           
                             
                               
                                 
                                   z 
                                   11 
                                 
                               
                               
                                 
                                   z 
                                   12 
                                 
                               
                               
                                 
                                   z 
                                   13 
                                 
                               
                               
                                 
                                   z 
                                   14 
                                 
                               
                             
                             
                               
                                 
                                   z 
                                   21 
                                 
                               
                               
                                 
                                   z 
                                   22 
                                 
                               
                               
                                 
                                   z 
                                   23 
                                 
                               
                               
                                 
                                   z 
                                   24 
                                 
                               
                             
                           
                           ] 
                         
                         ′ 
                       
                     
                     , 
                     
                       
 
                     
                      
                     
                       A 
                       = 
                       
                         [ 
                         
                           
                             
                               
                                 h 
                                 11 
                               
                             
                             
                               
                                 h 
                                 21 
                                 * 
                               
                             
                             
                               
                                 h 
                                 12 
                               
                             
                             
                               
                                 h 
                                 22 
                                 * 
                               
                             
                           
                           
                             
                               
                                 h 
                                 21 
                               
                             
                             
                               
                                 - 
                                 
                                   h 
                                   11 
                                   * 
                                 
                               
                             
                             
                               
                                 h 
                                 22 
                               
                             
                             
                               
                                 - 
                                 
                                   h 
                                   12 
                                   * 
                                 
                               
                             
                           
                           
                             
                               
                                 g 
                                 1 
                               
                             
                             
                               0 
                             
                             
                               
                                 g 
                                 2 
                               
                             
                             
                               0 
                             
                           
                           
                             
                               0 
                             
                             
                               
                                 g 
                                 1 
                                 * 
                               
                             
                             
                               0 
                             
                             
                               
                                 g 
                                 2 
                                 * 
                               
                             
                           
                         
                         ] 
                       
                     
                     , 
                     
                       
 
                     
                      
                     where 
                     , 
                     
                       
 
                     
                      
                     
                       c 
                       = 
                       
                         
                           [ 
                           
                             
                               
                                 0 
                               
                               
                                 0 
                               
                               
                                 
                                   
                                     
                                       
                                          
                                         
                                           g 
                                           1 
                                         
                                          
                                       
                                       2 
                                     
                                     + 
                                     
                                       
                                          
                                         
                                           g 
                                           2 
                                         
                                          
                                       
                                       2 
                                     
                                   
                                 
                               
                               
                                 0 
                               
                             
                             
                               
                                 0 
                               
                               
                                 0 
                               
                               
                                 0 
                               
                               
                                 
                                   
                                     
                                       
                                          
                                         
                                           g 
                                           1 
                                         
                                          
                                       
                                       2 
                                     
                                     + 
                                     
                                       
                                          
                                         
                                           g 
                                           2 
                                         
                                          
                                       
                                       2 
                                     
                                   
                                 
                               
                             
                           
                           ] 
                         
                         ′ 
                       
                     
                   
                 
               
               
                 
                   ( 
                   9 
                   ) 
                 
               
             
           
         
       
     
         [0067]    Next, STBC decoding may be performed with channel matching such that 
         [0000]    
       
         
           
             
               
                 
                   
                     
                       
                         [ 
                         
                           
                             
                               
                                 
                                   H 
                                   ~ 
                                 
                                 * 
                               
                             
                             
                               0 
                             
                           
                           
                             
                               0 
                             
                             
                               
                                 
                                   G 
                                   ~ 
                                 
                                 * 
                               
                             
                           
                         
                         ] 
                       
                        
                       
                         [ 
                         
                           
                             
                               
                                 
                                   r 
                                   ~ 
                                 
                                 1 
                               
                             
                           
                           
                             
                               
                                 
                                   r 
                                   ~ 
                                 
                                 2 
                               
                             
                           
                         
                         ] 
                       
                     
                     = 
                     
                       
                         
                           [ 
                           
                             
                               
                                 
                                   
                                     
                                       H 
                                       ~ 
                                     
                                     * 
                                   
                                    
                                   
                                     H 
                                     ~ 
                                   
                                 
                               
                               
                                 
                                   
                                     
                                       0 
                                     
                                   
                                   
                                     
                                       0 
                                     
                                   
                                 
                               
                             
                             
                               
                                 
                                   0 
                                    
                                   
                                       
                                   
                                    
                                   0 
                                 
                               
                               
                                 
                                   
                                     
                                       G 
                                       ~ 
                                     
                                     * 
                                   
                                    
                                   
                                     G 
                                     ~ 
                                   
                                 
                               
                             
                           
                           ] 
                         
                          
                         
                           [ 
                           
                             
                               
                                 
                                   c 
                                   1 
                                 
                               
                             
                             
                               
                                 
                                   c 
                                   2 
                                 
                               
                             
                           
                           ] 
                         
                       
                       + 
                       
                         [ 
                         
                           
                             
                               
                                 N 
                                 1 
                               
                             
                           
                           
                             
                               
                                 N 
                                 2 
                               
                             
                           
                         
                         ] 
                       
                     
                   
                    
                   
                     
 
                   
                    
                   
                     
                       
                         
                           
                             H 
                             ~ 
                           
                           * 
                         
                          
                         
                           H 
                           ~ 
                         
                       
                       = 
                       
                         
                           
                             ( 
                             
                               
                                 H 
                                 1 
                               
                               - 
                               
                                 
                                   [ 
                                   
                                     
                                       
                                         
                                           
                                             - 
                                             
                                               g 
                                               1 
                                             
                                           
                                            
                                           
                                             g 
                                             2 
                                             
                                               - 
                                               1 
                                             
                                           
                                         
                                       
                                       
                                         0 
                                       
                                     
                                     
                                       
                                         0 
                                       
                                       
                                         
                                           
                                             - 
                                             
                                               g 
                                               1 
                                               * 
                                             
                                           
                                            
                                           
                                             g 
                                             2 
                                             
                                               
                                                 - 
                                                 1 
                                               
                                               * 
                                             
                                           
                                         
                                       
                                     
                                   
                                   ] 
                                 
                                 × 
                                 
                                   H 
                                   2 
                                 
                               
                             
                             ) 
                           
                           * 
                         
                          
                         
                           ( 
                           
                             
                               H 
                               1 
                             
                             - 
                             
                               
                                 [ 
                                 
                                   
                                     
                                       
                                         
                                           - 
                                           
                                             g 
                                             1 
                                           
                                         
                                          
                                         
                                           g 
                                           2 
                                           
                                             - 
                                             1 
                                           
                                         
                                       
                                     
                                     
                                       0 
                                     
                                   
                                   
                                     
                                       0 
                                     
                                     
                                       
                                         
                                           - 
                                           
                                             g 
                                             1 
                                             * 
                                           
                                         
                                          
                                         
                                           g 
                                           2 
                                           
                                             
                                               - 
                                               1 
                                             
                                             * 
                                           
                                         
                                       
                                     
                                   
                                 
                                 ] 
                               
                               × 
                               
                                 H 
                                 2 
                               
                             
                           
                           ) 
                         
                       
                     
                     , 
                     
                       
 
                     
                      
                     where 
                     , 
                     
                       
 
                     
                      
                     
                       
                         
                           
                             G 
                             ~ 
                           
                           * 
                         
                          
                         
                           G 
                           ~ 
                         
                       
                       = 
                       
                         
                           ( 
                           
                             
                               
                                  
                                 
                                   g 
                                   1 
                                 
                                  
                               
                               2 
                             
                             + 
                             
                               
                                  
                                 
                                   g 
                                   2 
                                 
                                  
                               
                               2 
                             
                           
                           ) 
                         
                         × 
                         
                           [ 
                           
                             
                               
                                 1 
                               
                               
                                 0 
                               
                             
                             
                               
                                 0 
                               
                               
                                 1 
                               
                             
                           
                           ] 
                         
                       
                     
                     , 
                   
                 
               
               
                 
                   ( 
                   10 
                   ) 
                 
               
             
           
         
       
     
         [0068]    which is diagonalized and constant x identity. 
         [0069]      FIG. 7  is a basic diagram illustrating another embodiment of STBC realization or transmission with SDM by the receiver  721 . Multiple signals, c 1 (t), c 2 (t), c 3 (t), c 4 (t), c 5 (t) and c 6 (t), are received from an encoding block. After coding, c 1  and c 2  are transmitted through transmission antennas  710   a  and  710   b , and signals c 3 , c 4 , c 5  and c 6  are transmitted through transmission antennas  715   a  and  715   b . The signals c 1  and c 2  can be configured with conjugate values and signals c 3 , c 4 , c 5  and c 6  are being transmitted as in SDM with conjugates. The transmitted signals are received by the STBC decoding, block  721 , through receive antennas  720   a ,  720   b  and  720   c . After processing, signals, c 1  and c 2 , based on the originally transmitted signals are reformulated and output through outputs  751  and  752 . In general, the received signals are related to the source signals through an “H” or “G” component plus a noise term. 
         [0070]    From this set-up, the channels may be estimated as: 
         [0000]    
       
         
           
             
               
                 
                   
                     
                       
                         [ 
                         
                           
                             
                               
                                 r 
                                 1 
                               
                             
                           
                           
                             
                               
                                 r 
                                 2 
                               
                             
                           
                           
                             
                               
                                 r 
                                 3 
                               
                             
                           
                         
                         ] 
                       
                       
                         6 
                         × 
                         1 
                       
                     
                     = 
                     
                       
                         
                           
                             
                               [ 
                               
                                 
                                   
                                     
                                       H 
                                       1 
                                     
                                   
                                   
                                     
                                       G 
                                       1 
                                     
                                   
                                 
                                 
                                   
                                     
                                       H 
                                       2 
                                     
                                   
                                   
                                     
                                       G 
                                       2 
                                     
                                   
                                 
                                 
                                   
                                     
                                       H 
                                       3 
                                     
                                   
                                   
                                     
                                       G 
                                       3 
                                     
                                   
                                 
                               
                               ] 
                             
                             
                               6 
                               × 
                               6 
                             
                           
                            
                           
                             [ 
                             
                               
                                 
                                   
                                     c 
                                     1 
                                   
                                 
                               
                               
                                 
                                   
                                     c 
                                     2 
                                   
                                 
                               
                               
                                 
                                   
                                     c 
                                     3 
                                   
                                 
                               
                             
                             ] 
                           
                         
                         
                           6 
                           × 
                           1 
                         
                       
                       + 
                       
                         
                           [ 
                           
                             
                               
                                 
                                   n 
                                   1 
                                 
                               
                             
                             
                               
                                 
                                   n 
                                   2 
                                 
                               
                             
                             
                               
                                 
                                   n 
                                   3 
                                 
                               
                             
                           
                           ] 
                         
                         
                           6 
                           × 
                           1 
                         
                       
                     
                   
                    
                   
                     
 
                   
                    
                   where 
                   , 
                   
                     
 
                   
                    
                   
                     
                       c 
                       1 
                     
                     = 
                     
                       [ 
                       
                         
                           
                             
                               
                                 c 
                                 1 
                               
                                
                               
                                 ( 
                                 
                                   t 
                                   0 
                                 
                                 ) 
                               
                             
                           
                         
                         
                           
                             
                               
                                 c 
                                 2 
                               
                                
                               
                                 ( 
                                 
                                   t 
                                   0 
                                 
                                 ) 
                               
                             
                           
                         
                       
                       ] 
                     
                   
                   , 
                   
                     
                       c 
                       2 
                     
                     = 
                     
                       [ 
                       
                         
                           
                             
                               
                                 c 
                                 3 
                               
                                
                               
                                 ( 
                                 
                                   t 
                                   0 
                                 
                                 ) 
                               
                             
                           
                         
                         
                           
                             
                               
                                 c 
                                 4 
                               
                                
                               
                                 ( 
                                 
                                   t 
                                   0 
                                 
                                 ) 
                               
                             
                           
                         
                       
                       ] 
                     
                   
                   , 
                   
                     
                       c 
                       3 
                     
                     = 
                     
                       [ 
                       
                         
                           
                             
                               
                                 c 
                                 5 
                               
                                
                               
                                 ( 
                                 
                                   t 
                                   0 
                                 
                                 ) 
                               
                             
                           
                         
                         
                           
                             
                               
                                 c 
                                 6 
                               
                                
                               
                                 ( 
                                 
                                   t 
                                   0 
                                 
                                 ) 
                               
                             
                           
                         
                       
                       ] 
                     
                   
                   , 
                   
                     
 
                   
                    
                   
                     
                       r 
                       1 
                     
                     = 
                     
                       [ 
                       
                         
                           
                             
                               
                                 r 
                                 1 
                               
                                
                               
                                 ( 
                                 
                                   t 
                                   0 
                                 
                                 ) 
                               
                             
                           
                         
                         
                           
                             
                               
                                 r 
                                 1 
                                 * 
                               
                                
                               
                                 ( 
                                 
                                   t 
                                   1 
                                 
                                 ) 
                               
                             
                           
                         
                       
                       ] 
                     
                   
                   , 
                   
                     
                       r 
                       2 
                     
                     = 
                     
                       [ 
                       
                         
                           
                             
                               
                                 r 
                                 2 
                               
                                
                               
                                 ( 
                                 
                                   t 
                                   0 
                                 
                                 ) 
                               
                             
                           
                         
                         
                           
                             
                               
                                 r 
                                 2 
                                 * 
                               
                                
                               
                                 ( 
                                 
                                   t 
                                   1 
                                 
                                 ) 
                               
                             
                           
                         
                       
                       ] 
                     
                   
                   , 
                   
                     
                       r 
                       3 
                     
                     = 
                     
                       [ 
                       
                         
                           
                             
                               
                                 r 
                                 3 
                               
                                
                               
                                 ( 
                                 
                                   t 
                                   0 
                                 
                                 ) 
                               
                             
                           
                         
                         
                           
                             
                               
                                 r 
                                 3 
                                 * 
                               
                                
                               
                                 ( 
                                 
                                   t 
                                   1 
                                 
                                 ) 
                               
                             
                           
                         
                       
                       ] 
                     
                   
                   , 
                   
                     
 
                   
                    
                   
                     
                       H 
                       i 
                     
                     = 
                     
                       [ 
                       
                         
                           
                             
                               h 
                               
                                 1 
                                  
                                 i 
                               
                             
                           
                           
                             
                               h 
                               
                                 2 
                                  
                                 i 
                               
                             
                           
                         
                         
                           
                             
                               h 
                               
                                 2 
                                  
                                 i 
                               
                               * 
                             
                           
                           
                             
                               - 
                               
                                 h 
                                 
                                   1 
                                    
                                   i 
                                 
                                 * 
                               
                             
                           
                         
                       
                       ] 
                     
                   
                   , 
                   
                     
                       G 
                       i 
                     
                     = 
                     
                       [ 
                       
                         
                           
                             
                               g 
                               
                                 1 
                                  
                                 i 
                               
                             
                           
                           
                             0 
                           
                           
                             
                               g 
                               
                                 2 
                                  
                                 i 
                               
                             
                           
                           
                             0 
                           
                         
                         
                           
                             0 
                           
                           
                             
                               g 
                               
                                 1 
                                  
                                 i 
                               
                               * 
                             
                           
                           
                             0 
                           
                           
                             
                               g 
                               
                                 2 
                                  
                                 i 
                               
                               * 
                             
                           
                         
                       
                       ] 
                     
                   
                 
               
               
                 
                   ( 
                   11 
                   ) 
                 
               
             
           
         
       
     
         [0071]    To cancel the interference, zero forcing is applied such that: 
         [0000]    
       
         
           
             
               
                 
                     
                   
                     
                       
                         [ 
                         
                           
                             
                               
                                   
                               
                             
                             
                               
                                 [ 
                                 
                                   
                                     
                                       1 
                                     
                                     
                                       0 
                                     
                                   
                                   
                                     
                                       0 
                                     
                                     
                                       1 
                                     
                                   
                                 
                                 ] 
                               
                             
                             
                               
                                   
                               
                             
                             
                               
                                   
                               
                             
                             
                               
                                 [ 
                                 
                                   
                                     
                                       
                                         a 
                                         1 
                                       
                                     
                                     
                                       0 
                                     
                                     
                                       
                                         a 
                                         2 
                                       
                                     
                                     
                                       0 
                                     
                                   
                                   
                                     
                                       0 
                                     
                                     
                                       
                                         a 
                                         1 
                                         * 
                                       
                                     
                                     
                                       0 
                                     
                                     
                                       
                                         a 
                                         2 
                                         * 
                                       
                                     
                                   
                                 
                                 ] 
                               
                             
                             
                               
                                   
                               
                             
                           
                           
                             
                               
                                 z 
                                 11 
                               
                             
                             
                               
                                 z 
                                 12 
                               
                             
                             
                               
                                 z 
                                 13 
                               
                             
                             
                               
                                 z 
                                 14 
                               
                             
                             
                               
                                 z 
                                 15 
                               
                             
                             
                               
                                 z 
                                 16 
                               
                             
                           
                           
                             
                               
                                 z 
                                 21 
                               
                             
                             
                               
                                 z 
                                 22 
                               
                             
                             
                               
                                 z 
                                 23 
                               
                             
                             
                               
                                 z 
                                 24 
                               
                             
                             
                               
                                 z 
                                 25 
                               
                             
                             
                               
                                 z 
                                 26 
                               
                             
                           
                           
                             
                               
                                 z 
                                 31 
                               
                             
                             
                               
                                 z 
                                 32 
                               
                             
                             
                               
                                 z 
                                 33 
                               
                             
                             
                               
                                 z 
                                 34 
                               
                             
                             
                               
                                 z 
                                 35 
                               
                             
                             
                               
                                 z 
                                 36 
                               
                             
                           
                           
                             
                               
                                 z 
                                 41 
                               
                             
                             
                               
                                 z 
                                 42 
                               
                             
                             
                               
                                 z 
                                 43 
                               
                             
                             
                               
                                 z 
                                 44 
                               
                             
                             
                               
                                 z 
                                 45 
                               
                             
                             
                               
                                 z 
                                 46 
                               
                             
                           
                         
                         ] 
                       
                       × 
                       
                         [ 
                         
                           
                             
                               
                                 r 
                                 1 
                               
                             
                           
                           
                             
                               
                                 r 
                                 2 
                               
                             
                           
                           
                             
                               
                                 r 
                                 3 
                               
                             
                           
                         
                         ] 
                       
                     
                     = 
                     
                         
                       
                         
                           
                             [ 
                             
                               
                                 
                                   
                                     
                                       r 
                                       ~ 
                                     
                                     1 
                                   
                                 
                               
                               
                                 
                                   
                                     
                                       r 
                                       ~ 
                                     
                                     2 
                                   
                                 
                               
                               
                                 
                                   
                                     
                                       r 
                                       ~ 
                                     
                                     3 
                                   
                                 
                               
                             
                             ] 
                           
                           = 
                           
                             
                               
                                 
                                   [ 
                                   
                                     
                                       
                                         
                                           H 
                                           ~ 
                                         
                                       
                                       
                                         0 
                                       
                                     
                                     
                                       
                                         0 
                                       
                                       
                                         
                                           G 
                                           ~ 
                                         
                                       
                                     
                                   
                                   ] 
                                 
                                 
                                   6 
                                   × 
                                   6 
                                 
                               
                               × 
                               
                                 [ 
                                 
                                   
                                     
                                       
                                         c 
                                         1 
                                       
                                     
                                   
                                   
                                     
                                       
                                         c 
                                         2 
                                       
                                     
                                   
                                   
                                     
                                       
                                         c 
                                         3 
                                       
                                     
                                   
                                 
                                 ] 
                               
                             
                             + 
                             
                               
                                 [ 
                                 
                                   
                                     
                                       
                                         
                                           n 
                                           ~ 
                                         
                                         1 
                                       
                                     
                                   
                                   
                                     
                                       
                                         
                                           n 
                                           ~ 
                                         
                                         2 
                                       
                                     
                                   
                                   
                                     
                                       
                                         
                                           n 
                                           ~ 
                                         
                                         3 
                                       
                                     
                                   
                                 
                                 ] 
                               
                                
                               
                                 
 
                               
                                
                               where 
                             
                           
                         
                         , 
                         
                            
                         
                          
                         
                           
                             
                               H 
                               ~ 
                             
                             
                               2 
                               × 
                               2 
                             
                           
                           = 
                           
                             
                               H 
                               1 
                             
                             - 
                             
                               
                                 [ 
                                 
                                   
                                     
                                       
                                         a 
                                         1 
                                       
                                     
                                     
                                       0 
                                     
                                     
                                       
                                         a 
                                         2 
                                       
                                     
                                     
                                       0 
                                     
                                   
                                   
                                     
                                       0 
                                     
                                     
                                       
                                         a 
                                         1 
                                         * 
                                       
                                     
                                     
                                       0 
                                     
                                     
                                       
                                         a 
                                         2 
                                         * 
                                       
                                     
                                   
                                 
                                 ] 
                               
                               × 
                               
                                 [ 
                                 
                                   
                                     
                                       
                                         H 
                                         2 
                                       
                                     
                                   
                                   
                                     
                                       
                                         H 
                                         3 
                                       
                                     
                                   
                                 
                                 ] 
                               
                             
                           
                         
                         , 
                         
                           
 
                         
                          
                         
                           
                             
                               G 
                               ~ 
                             
                             
                               4 
                               × 
                               4 
                             
                           
                           = 
                           
                             [ 
                             
                               
                                 
                                   
                                     
                                       
                                         
                                           ∑ 
                                           
                                             i 
                                             = 
                                             1 
                                           
                                           3 
                                         
                                          
                                         
                                           
                                              
                                             
                                               g 
                                               
                                                 1 
                                                  
                                                 
                                                     
                                                 
                                                  
                                                 i 
                                               
                                             
                                              
                                           
                                           2 
                                         
                                       
                                     
                                     × 
                                     
                                       I 
                                       
                                         2 
                                         × 
                                         2 
                                       
                                     
                                   
                                 
                                 
                                   0 
                                 
                               
                               
                                 
                                   0 
                                 
                                 
                                   
                                     
                                       
                                         
                                           ∑ 
                                           
                                             i 
                                             = 
                                             1 
                                           
                                           3 
                                         
                                          
                                         
                                           
                                              
                                             
                                               g 
                                               
                                                 2 
                                                  
                                                 
                                                     
                                                 
                                                  
                                                 i 
                                               
                                             
                                              
                                           
                                           2 
                                         
                                       
                                     
                                     × 
                                     
                                       I 
                                       
                                         2 
                                         × 
                                         2 
                                       
                                     
                                   
                                 
                               
                             
                             ] 
                           
                         
                         , 
                       
                     
                   
                 
               
               
                 
                   ( 
                   12 
                   ) 
                 
               
             
           
         
       
     
         [0072]    Thereafter Z is found by zero-forcing to minimize noise enhancement, such that: 
         [0000]        z =( AA *) −1   A*c   (13) 
         [0000]    where, 
         [0000]    
       
         
           
             
               z 
               = 
               
                 
                   [ 
                   
                     z 
                     ij 
                   
                   ] 
                 
                 ′ 
               
             
             , 
             
               c 
               = 
               
                 
                   [ 
                   
                     
                       
                         
                           0 
                           
                             2 
                             × 
                             4 
                           
                         
                       
                       
                         
                           
                             G 
                             ~ 
                           
                           
                             4 
                             × 
                             4 
                           
                         
                       
                     
                   
                   ] 
                 
                 ′ 
               
             
             , 
             
               A 
               = 
               
                 
                   [ 
                   
                     
                       
                         
                           H 
                           1 
                         
                       
                       
                         
                           G 
                           1 
                         
                       
                     
                     
                       
                         
                           H 
                           2 
                         
                       
                       
                         
                           G 
                           2 
                         
                       
                     
                     
                       
                         
                           H 
                           3 
                         
                       
                       
                         
                           G 
                           3 
                         
                       
                     
                   
                   ] 
                 
                 ′ 
               
             
           
         
       
     
         [0000]    and a 1  and a 2  are also found by zero forcing 
         [0000]    
       
         
           
             
               [ 
               
                 
                   
                     
                       a 
                       1 
                     
                   
                 
                 
                   
                     
                       a 
                       2 
                     
                   
                 
               
               ] 
             
             = 
             
               
                 
                   [ 
                   
                     
                       
                         
                           g 
                           12 
                         
                       
                       
                         
                           g 
                           13 
                         
                       
                     
                     
                       
                         
                           g 
                           22 
                         
                       
                       
                         
                           g 
                           23 
                         
                       
                     
                   
                   ] 
                 
                 
                   - 
                   1 
                 
               
               × 
               
                 
                   [ 
                   
                     
                       
                         
                           - 
                           
                             g 
                             11 
                           
                         
                       
                     
                     
                       
                         
                           - 
                           
                             g 
                             21 
                           
                         
                       
                     
                   
                   ] 
                 
                 . 
               
             
           
         
       
     
         [0073]    Next, STBC decoding may be performed with channel matching in processes similar to those discussed in the above-discussed embodiments. In all of the above discussed embodiments, at least a pair of transmit antennas are used for STBC (c 1 (t 0 ) and c 2 (t 0 )), the other transmit antennas may transmit SDM signals. Thus, while only the first two sequences, c 1 (t) and c 2 (t), will obtain diversity gain, but there may be additional coding gains based on good quality bits. The additional sequences provide signal-to-noise advantages using repetition codes. 
         [0074]    Although the invention has been described based upon these preferred embodiments, it would be apparent to those skilled in the art that certain modifications, variations, and alternative constructions would be apparent, while remaining within the spirit and scope of the invention. In order to determine the metes and bounds of the invention, therefore, reference should be made to the appended claims.