Research On Cooperative Transmission Scheme Based On Distributed Antennas Chain

The applications for communication expand quickly accompanied with the rapid development of wireless communication technology. However, in the high-speed moving scenes, the mobile communication system faces with the problem of the data service can not be met for the large value of Doppler shift and the rapid changes of channel state information, which making it a bottleneck in the development of wireless communication. In recent years, distributed antenna chain system has got a lot of attention for its performance improvement under the high-speed mobile scene. In addition, the theoretical research is mature for the cooperative communication technology, the wireless cooperative communication systems utilize communication terminals located in different geographical locations to form a virtual multiple-input multiple-output system, which enabling the larger-capacity and the longer-distance transmission of wireless communication system. Therefore, this thesis research a cooperative transmission scheme based on distributed antennas chain by combining the advantages of distributed antennas chain system and cooperative communication. The relays composed by distributed antennas chain can solve the installation difficulty of multiple antennas on one node, and the cooperative technology applied to the distributed antennas chain system can solve the problem of low bit error rate performance effectively in the high-speed communication scene. Depend on the background of high-speed communication scene, the research is organized as follows:(1) Analyze the relationship between the transmission performance and the control protocol, the terminal speed, the path loss and the frequency of handoff.(2) As the degradation of high speed mobile communication system performance caused by the frequent handoff, the simulation for the distributed antenna chain system is simulated to analyze the influence between the system performance with the cell coverage, the carrier to interference ratio and the system co-channel interference ratio.(3) This thesis proposes a cooperative transmission scheme based on distributed antennas chain by combining the advantages of the distributed antennas chain and the cooperative communication. The transmission scheme complete a communication process course by two time slots.In the first time slot, the source node broadcasts the data symbols to the relay nodes and the destination node by coding and orthogonal frequency division multiplexing (OFDM) modulation. In the second time slot, according to its own distributed antennas chain, the relay nodes retransmit the received data symbols to the destination node by cyclic delay and amplify forwarded, simultaneously, the source node continues to send next modulation data symbol towards the destination node. The MATLAB simulations verify the performance improvement of symbol error rate and spectrum efficiency.