Research On Space-Time Block Code For SC-FDE System

Space-time block codes (STBC) can get some diversity gain with multiple antennas over multipath channel, improve BER performance of the system, and increase the wireless transmission distance.In the frequency selective fading channels, Single carrier frequency domain equalization (SC-FDE) can be effective against interference between data blocks (IBI) caused by the multipath channel. Compared with OFDM, the transmission scheme of SC-FDE has the advantages of lower PAPR and less sensitivity to frequency offset. STBC in the SC-FDE system can take advantage of the superiority of two schemes, and have wide prospects. Currently the research works on STBC in the SC-FDE system are focused on orthogonal space-time block code (OSTBC). For the complex signal encoding, OSTBC can not reach full speed transmission when the number of transmit antennas is greater than2.To solve above problems, this paper studies the quasi-orthogonal space-time block code (QOSTBC) in the SC-FDE system. We propose the encoding and decoding methods about QOSTBC with Givens rotation in the SC-FDE system for three and four transmit antennas, which can achieve the full rate compared with the OSTBC in the SC-FDE system. Compared with the traditional QOSTBC in the SC-FDE system, the schemes we proposed also have merits. Firstly, the method we proposed after the Givens rotation, the equivalent channel matrix and the encoding matrix are both orthogonal matrix. The proposed method can eliminate interference between the different symbols, implement linear decoding and reduce the complexity of decoding. Secondly, the proposed scheme has better error performance.Finally, the paper studies the concatenated coding about the QOSTBC based Givens rotation and convolutional codes in the SC-FDE system. By concatenated coding, the system can simultaneously obtain diversity gain and coding gain to further reduce the error rate.