257 results about "Space time block coded" patented technology

Disclosed is an apparatus and method for adaptively allocating transmission power for beamforming combined with orthogonal space-time block codes (OSTBC) in a distributed wireless communication system, the apparatus comprising: a plurality of sub-arrays for beamforming, which are geographically distributed and each of which comprises a plurality of distributed antennas placed in random groups; and a central processing unit for identifying performances of subsets by applying a predetermined power allocation scheme according to subsets which can be obtained by combining the sub-arrays, by means of a Nakagami fading parameter and information about large-scale fading of each of the sub-arrays, fed back from a receiving party, for determining a subset having a best performance as an optimal subset according to the identified performances, and for performing power allocation based on the subset set as the optimal subset.

A method is provided for transmitting signals from a transmitter comprising two or more antennas in a mobile telecommunications network. The method involves determining channel state information, estimating the reliability of that channel state information, and space time block encoding at least one data sequence. Before transmitting the data sequence, a linear transformation is applied to the data sequence so as to at least partially compensate for channel variations. The linear transformation is dependent upon the channel state information and upon the estimated reliability of the channel state information.

An apparatus that adaptively allocates transmission power for beam-forming combined with orthogonal space time block codes in a distributed wireless communication system, the apparatus including: sub-arrays for beam-forming, which are geographically distributed and each of which includes a plurality of distributed antennas placed in random groups. A central processing unit provides predetermined combinable power allocation schemes according to subsets in a plurality of the sub-arrays, identifying performances of the schemes by using information on large-scale fading of each of the sub-arrays fed back from a receiving party, setting a subset having best performance as an optimal subset according to the identified performances, and performing power allocation according thereto.

A method is provided of transmitting signals from two or more antennas in a wireless telecommunications network, in which at least one data sequence is space-time block encoded. Before transmitting the data sequence, a linear transformation is applied to the data sequence, the linear transformation being adapted to use knowledge of correlation among the antennas to at least partially compensate the transmitted signals for said correlation. The linear transformation depends on the eigenvalues of an antenna correlation matrix. The linear transformation further depends on a ratio of symbol energy (E_s) to noise variance (σ²). The method includes transmitting the encoded and transformed data sequence.

Transmitters, receivers, and methods for providing improved transmit diversity orthogonal frequency division multiplexed communication systems is provided.

Methods, systems and apparatuses are provided for transmitting and receiving space-time block coded data in a wireless communications system with co-operative relays. A source node transmits RF signals representing first and second sets of data symbols in respective first and second channels (in time frequency code or any combination) of a wireless communications system, the first and second sets of data symbols being for transmission from separate antennas respectively according to a space-time block code. A relay node receives the RF signals representing the first set of data symbols in the first channel and transmits RF signals representing the first set of data symbols in the second channel. A destination node received the RF signals representing the second set of data symbols from the source node and the RF signals representing the first set of data symbols from the relay node. This enables decoding of the received RF signals representing the first and second sets of data symbols according to the space-time block code.

Disclosed is a device for allocating transmission power using a symbol error rate (SER) for orthogonal space-time block codes (OSTBC) in a wireless communication system. The device includes: a plurality of antennas, which are distributed geographically and independently linked to a central processing unit; a receiver to select an optimum subset of the SER performance, using a preset power allocation to each of available antenna subset combinations, and sending the selected subset to a transmitter; and a central processing unit to allocate power by applying an OSTBC symbol having a unit average power to the optimum subset from the receiver.

Embodiments of the invention provide orthogonal Frequency Division Multiplexing-Space-time Block Codes (OFDMSTBC) mappings for code rate 1, 2 and 4 codes for 4 Transmit Antennas. To overcome the innate weakness of known codes, a new class of STBC codes is provided which is particularly suited for OFDM applications, although other applications are also contemplated. Codes for STBC mappings in the time direction, the frequency direction and a combined time frequency mapping for multiple antennas are provided. In OFDM applications, these codes exploit the properties of OFDM and FEC codes to substantially maintain the advantages of Alamouti codes. Furthermore, while the detailed examples given herein focus on four antenna applications, they can be easily extended to systems with more than four antennas.

The present invention relates to a method and apparatus for transmitting and receiving signals using a Physical layer Protocol Data unit (PPDU) format to which Space-Time Block Coding (STBC) is applied in a Wireless Local Area Network (WLAN). According to one aspect of the present invention, a method for transmitting data to a plurality of Stations (STAs) on a transmission channel by an Access Point (AP) in a WLAN may be provided. The transmission channel may be divided into a plurality of subchannels allocated to the plurality of STAs. The method may include generating a High Efficiency-Long Training Field (HE-LTF) field having a length determined based on whether Space-Time Block Coding (STBC) is applied to the plurality of subchannels, and transmitting a Physical layer Protocol Data Unit (PPDU) frame including the HE-LTF field and a plurality of data units for the plurality of STAs to the plurality of STAs.

A coding technique for achieving a maximum diversity gain in a wireless communication system having a transmitter for transmitting data on a fading channel through a plurality of transmit antennas and a receiver for receiving the data through a plurality of receive antennas. In the coding technique, P m^th-order sub-rotated vectors {right arrow over (r)}_i are generated by constellation-rotating an L^th-order input vector {right arrow over (x)} including a plurality of input symbols modulated in at least one modulation scheme. m p^th-order sub-vectors {right arrow over (u)}_i are generated using the sub-rotated vectors {right arrow over (r)}_i. Codeword matrices A_i({right arrow over (u)}_i) are generated by performing orthogonal space-time block coding on the sub-vectors {right arrow over (u)}_i and then transmitted through the transmit antennas.

The transmit diversity and symbol rate in a wireless mobile system are increased by allocating the complex symbols to be transmitted in accordance with a time-space slot format that incorporates non-orthogonal-based matrices, defined as matrices whose format is such that the product of the matrix and its Hermitian transpose is other than the identity matrix times a real number other than unity. The non-orthogonal-based matrices are indexed by antenna and by symbol period. Copies and complex conjugates (or negative complex conjugates) of the same symbol that are transmitted from different antennas are mutually separated into non-adjacent parts of the slot. Each non-orthogonal-based "space-time" matrix is composed of orthogonal-based matrices, i.e., matrices other than non-orthogonal-based matrices. Preferably, sequences of complex conjugates are time-reversed in the slot.

Enhanced performance is achieved by combining channel coding with the space-time coding principles. With K synchronized terminal units transmitting on N antennas to a base station having M≧K receive antennas, increased system capacity and improved performance are attained by using a concatenated coding scheme where the inner code is a space-time block code and the outer code is a conventional channel error correcting code. Information symbols are first encoded using a conventional channel code, and the resulting signals are encoded using a space-time block code. At the receiver, the inner space-time block code is used to suppress interference from the other co-channel terminals and soft decisions are made about the transmitted symbols. The channel decoding that follows makes the hard decisions about the transmitted symbols. Increased data rate is achieved by, effectively, splitting the incoming data rate into multiple channels, and each channel is transmitted over its own terminal.

In a method of transmitting a data stream from a transmitter in a multiple-input-multiple-output (MIMO) wireless communication system, where the transmitter comprises a plurality of transmit antennas, a discrete Fourier transform (DFT) is applied to the data stream to generate a plurality of symbol sequences; symbols of a first symbol sequence from the plurality of symbol sequences are paired with symbols of a second symbol sequence from the plurality of symbol sequences to generate a plurality of symbol pairs, wherein the pairing results in an orphan symbol; a space-time block code (STBC) is applied to the symbol pairs to generate a plurality of sets of STBC symbols, each set of STBC symbols being associated with a corresponding one of the plurality of antennas; a cyclic delay diversity (CDD) operation is applied to the orphan symbol to generate a plurality of CDD symbols, each CDD symbol being associated with a corresponding one of the plurality of antennas; and each one of the antennas transmits the corresponding set of STBC symbols and the corresponding CDD symbol.

A space-time block coding apparatus and method in a transmitter with four transmit antennas in a system using a space-time block coding scheme, a pre-coder pre-codes an input symbol sequence by multiplying the input symbol sequence by e^jθ, θ being a phase rotation angle, in case of QPSK in range of 0≦θ≦90, 23.5≦θ≦24.5, or 65.5≦θ≦66.5, in case of 16QAM in range of 0≦θ≦90, 15.5≦θ≦17.5 or 72.5≦θ≦74.5, the pre-coded symbol sequence being reconstructed to have real and imaginary parts. A mapper generates symbol vectors by recombining the real and imaginary parts of the pre-coded symbol sequence in an interleaving scheme. A plurality of Alamouti coders encodes the symbol vectors in an Alamouti scheme and transmits the encoded symbol vectors through corresponding transmit antennas.

In a particular embodiment, a method includes applying a first stream to antenna mapping scheme to a preamble portion of a packet. The method further includes applying a second stream to antenna mapping scheme to a data portion of the packet. The second stream to antenna mapping scheme is applied to the data portion of the packet but not to the preamble portion of the packet. The second stream to antenna mapping scheme includes a circulation scheme or a cyclic delay diversity (CDD) scheme.

Disclosed is an apparatus and method for encoding/decoding a space time block code in a mobile communication system using a multiple input multiple output scheme. In a transmitter employing a plurality of transmit antennas in the mobile communication system, if a signal to be transmitted is input, the transmit signal is pre-encoded according to a preset coding scheme, the pre-encoded signal is space-time mapped according to a number of the transmit antennas to employ a preset space time block coding scheme, and the space-time mapped signal is transmitted through the transmit antennas by applying the preset space time block coding scheme to the space-time mapped signal.

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.