The Cooperative Relay Communication Based On Jafarkhani Code

With the rapid development of wireless communication technology, the third-generation mobile communication (3G) technology tends into application. But the problem of slowing data transmission speed is also increasingly apparent. For example, data rates of these new interactive multimedia businesses usually need to reach tens or even hundreds of megabytes in bits per second, however,3G technology cannot fulfill this requirement clearly. MIMO technology is the advanced technology that can significantly increase the channel capacity. OFDM technology can greatly improve spectral efficiency, and cooperative communication can not only improve the system capacity in the case of a single antenna but also improve resource utilization. Moreover MIMO, OFDM and cooperative communication all can greatly improve system performance. Thus they have become the key technologies for future mobile communications.In order to solve the problem of slowing data rate, spectrum efficiency and limited resources, the cooperative relay communication scheme based on Jafarkhani codes in the basis of MIMO, OFDM and cooperative communication technology is proposed in this thesis. Firstly, a simple cooperative communication scheme is introduced based on Jafarkhani code, in which the cooperative communication model is applied and there is a source node, a destination node and two relay nodes. The relay node amplifies the signal which comes from the source node and transmits it to destination node. Thus the signal of the destination node has Jafarkhani code structure and the maximum likelihood decoding method can be utilized. It demonstrates that the scheme can reduce the complexity of decoding without sacrificing the performance. Secondly, the Jacket matrix can replace the FFT modulation method of cooperative relay communication since it has inverse characteristic, simple calculation, and easy implement. Therefore a space-time cooperative communication scheme is further proposed based on the Jacket transform, which has the characteristics of low computational complexity, easy implement, good performance and certain flexibility. Finally, the thesis is extended to the new scheme in MIMO systems. The signal processing method of the relay node is redefined, such that the reception signal in the target node can be still decoded with the maximum likelihood decoding method. Compared with the SISO scheme, the system performance of the MIMO scheme is much better in the case of the same signal-to-noise ratio.In conclusion, the presented cooperative relay communication scheme which is based on Jafarkhani code can improve the system performance, system capacity and spectrum utilization in a certain extent. It makes scarce resources better utilized and has great practical application values.