Research On Differential Space-Time-Frequency Coding Scheme In Wireless Cooperative Communication Network

In wireless cooperative communication network, distributed differential space-time-frequency (DSTF) coding is to realize the information coding and transmission by a reasonable coding scheme on the condition that the channel state information is not available to the relay node and the receiver. Distributed DSTF coding can particularly obtain space and frequency diversity, reduce the detection complexity and node power consumption, and enhance the anti-jamming capability and bit error performance of the whole network. This dissertation's mainly research work is as follows:(1) The basic principle of space-time-frequency coding is introduced. The history and various standards of space-time-frequency coding are discussed.(2) DSTF scheme is analyzed on the basis of space-time-frequency coding structure. The simulation results confirm that rate embedded DSTF coding scheme, especially in the case of high spectral efficiency or large number of transmit antennas, has extremely obvious higher bit error rate(BER) performance and higher frequency spectrum efficiency than the existing space-time-frequency coding.(3) Based on a cooperative communications research background, a asynchronous distributed DSTF coding is proposed by using the amplify-and-forward protocol. The scheme firstly divides the source data packet into groups, thereby reducing the coding complexity. At the same time by applying full diversity rotation, Cayley transformation and OFDM modulation at the source node and then amplifying and forwarding the received signal at the relays, a distributed DSTF code is constructed. Simulation results show that, The proposed scheme can achieve both spatial and multi-path diversities without either perfect synchronization at the relays or any instantaneous channel state information at the destination node.