Reserch On Multiple Antennas And Relays Coordinate Differential Coding Scheme Based On CDD Technology

Recently, wireless communication system is developing rapidly, the demand of wireless communication business for the human society is increasing,the requirements of quality indexes in a communication system improve continually. As a multiple antenna system,the MIMO (Multiple Input Multiple Output) technology can improve the space diversity gain greatly,but due to the restraints of actual conditions in the application process, the generation of cooprative communication is to solve this difficulty, through using multiple relay nodes work together, it can form a virtual MIMO system and be obtained the space diversity gain which is close to the MIMO system, however the distributed MIMO system has been improved space diversity gain of the system widerly.In the studies of signal transmission in the wireless communication network, most of them are based on the assumption of channel state information known to the receiver. It’s need to know the channel state information fully, in other words it will increase the burden of channel estimation. However, In the differential space-time coding scheme, under the condition of transmitter and the receiver does not need to know the channel state information, the receiver can detect the received signal and decode, so that channel estimation can be avoided.In this thesis, we first reserch the system model of MIMO、the OFDM (Orthogonal Frequency Division Multiplexing) modulation theory and several classical space-time frequency encodings, mainly reserch the differential space-time coding scheme in the MIMO system. Then reserch the wireless cooperative communication system model, diversity technique and several classic forwarding protocols, in addition compare the simulation of the error performance under the agreement between ampliy forward and decode forward,mainly introduce differential modulation and CDD (Cyclic Delay Diversity) technology in the wireless communication network, the simulation verifies the optimization of system error performance in the differential cooperative system combined with CDD technology. In this thesis, based on the concept of distributed MIMO, all nodes of the collaboration relay system have many transmitting antennas assembly, combined with the cyclic delay diversity and different coding technology, designed to improve the system ber performance and reduce the detection complexity. Firstly we study the collaborative MIMO system assembly two antennas, followed by the study of the coordination scheme with multiple antennas and multiple relays based on the technology of CDD and different coding, the relay nodes amplify the received signals from the source and forward to the destination, through the theoretical analysis and simulation experiment,we can prove that under the premise of the receiving end don’t know channel state information, combined with the CDD technology and different coordination scheme can improve the performance of the system, and has low detection complexity.