Abstract: A multiple-hop multi-input multi-output (MIMO) amplify-and-forward relay wireless communication system includes a signal source node, a signal destination node and a plurality of relay nodes, wirelessly coupled between the signal source node and the signal destination node. The relay nodes feed back a plurality of signal to noise ratio information and a plurality of antenna number information to the signal source node. The signal source node allocates a plurality of corresponding transmission powers for the relay nodes and sends to the relay nodes.

Abstract: A guard section length detection method detects whether a preamble signal is received. A short preamble boundary is then detected, then detecting a frame boundary and detecting a guard section length. In the step of detecting the guard section length a second matched filter capable of processing 128 point data sets is detected. Four different 128 point data sets have a distance of 8 points, 16 points, 32 points, and 64 points respectively from the frame boundary to the second matched filter. Four signal correlation values are calculated for determining the guard section length.

Abstract: An adaptive channel estimator for estimating channel frequency responses when receiving OFDM symbols. The adaptive channel estimator comprises a channel estimator and a channel tracking module. The channel estimator generates one first channel frequency response for each OFDM symbol when operated in the first mode, and generates the channel frequency responses of a second channel frequency response for every N-th OFDM symbols when operated in the second mode, wherein N is a constant integer exceeding one and j is a non-negative integer. The channel tracking module indicates a channel status, and controls the channel estimator to operate in a first mode or a second mode according to the channel status.

Abstract: A guard section length detection method is disclosed. In the method, a guard section length detection method is used in an OFDM system. The OFDM symbol includes a data interval having a first length, and a guard section having a guard section length. The method detects a first symbol boundary and a second symbol boundary, and determines the guard section length based on a length between the first symbol boundary and the second symbol boundary.

Abstract: A receiving end apparatus disposes a spatial data combining circuit at symbol level and disposes an HARQ data combining circuit and/or the repetition data combining circuit at bit level. The spatial data combining is performed before the de-mapping, while the de-repetition and/or the HARQ chase combining are performed after the de-mapping. This apparatus configuration can significantly reduce the buffer size and the computation complexity required so the overall performance is therefore improved.

Abstract: A method for compensating IQ imbalance is disclosed. First, an OFDM signal is received. The OFDM signal is translated into frequency domain, wherein the translated OFDM signal has N sub-carriers noted as Y(1)-Y(N). The IQ imbalance compensation factor is generated according to the k-th sub-carrier of the translated signal Y(k), the (N?k+2)-th sub-carrier of the translated signal Y(N?k+2), and the complex conjugates thereof.

Abstract: The present invention provides an antenna-array-based multiple-input multiple-output orthogonal-frequency-division-multiplexing (MIMO-OFDM) system and a pre-coding and feedback method used in the same. The present invention uses QR decompositions of the MIMO channel matrixes to parameterize the channel state information (CSI) of every OFDM frequency band. In addition, the present invention feeds back the information related to ? and ? in the Givens rotation matrixes of the partial frequency bands and then uses an interpolation method to generate ? and ? in the Givens rotation matrixes of all the frequency bands, which further is able to represent the CSI of all the frequency bands. In this way, the present invention has advantages of low complexity and low feedback rate requirement.

Abstract: A method for compensating IQ imbalance is disclosed. First, an OFDM signal is received. The OFDM signal is translated into frequency domain, wherein the translated OFDM signal has N sub-carriers noted as Y(1)-Y(N). The IQ imbalance compensation factor is generated according to the k-th sub-carrier of the translated signal Y(k), the (N?k+2)-th sub-carrier of the translated signal Y(N?k+2), and the complex conjugates thereof.

Abstract: An adaptive channel estimator for estimating channel frequency responses when receiving OFDM symbols. The adaptive channel estimator comprises a channel estimator and a channel tracking module. The channel estimator generates one first channel frequency response for each OFDM symbol when operated in the first mode, and generates the channel frequency responses of a second channel frequency response for every N-th OFDM symbols when operated in the second mode, wherein N is a constant integer exceeding one and j is a non-negative integer. The channel tracking module indicates a channel status, and controls the channel estimator to operate in a first mode or a second mode according to the channel status.

Abstract: A guard section length detection method is disclosed. In the method, a guard section length detection method is used in an OFDM system. The OFDM symbol includes a data interval having a first length, and a guard section having a guard section length. The method detects a first symbol boundary and a second symbol boundary, and determines the guard section length based on a length between the first symbol boundary and the second symbol boundary.

Abstract: A guard section length detection method detects whether a preamble signal is received. A short preamble boundary is then detected, then detecting a frame boundary and detecting a guard section length. In the step of detecting the guard section length a second matched filter capable of processing 128 point data sets is detected. Four different 128 point data sets have a distance of 8 points, 16 points, 32 points, and 64 points respectively from the frame boundary to the second matched filter. Four signal correlation values are calculated for determining the guard section length.

Abstract: The present invention provides an antenna-array-based multiple-input multiple-output orthogonal-frequency-division-multiplexing (MIMO-OFDM) system and a pre-coding and feedback method used in the same. The present invention uses QR decompositions of the MIMO channel matrixes to parameterize the channel state information (CSI) of every OFDM frequency band. In addition, the present invention feeds back the information related to ? and ? in the Givens rotation matrixes of the partial frequency bands and then uses an interpolation method to generate ? and ? in the Givens rotation matrixes of all the frequency bands, which further is able to represent the CSI of all the frequency bands. In this way, the present invention has advantages of low complexity and low feedback rate requirement.