Research On Relaying Technologies In Cooperative Communication

Space, or multiple-antenna, diversity techniques are particularly attractive as they can be readily combined with other forms of diversity, e.g., time and frequency diversity, and still offer dramatic performance gains when other forms of diversity are unavailable. It is difficult for mobile users to achieve MIMO techniques, these mobile terminals inability to equip-multiple antennas due to the constraints with the size,power or the cost,which also leads to new direction for application of MIMO.In contrast to the more conventional forms of multiple-antenna techniques, in wireless network, users can cooperate by relaying information for one another when they are idle, to form a virtual multiple-antenna system, thus achieving space diversity and enhancing the system performance and robustness to fading under the premise of using single antenna terminal. We refer to this form of communication as cooperative communication.On the basis of international current research works,this thesis investigates some key theories and technologies for cooperative communication systems in depth, and presents some new contributions in the following topics: Transmit diversity-based cooperative communication systems with Multi-point relays, Fixed multi-antenna relay network, incremental cooperative relaying protocol. The following contents are the main work in this thesis:(1) A two-hop multi-point cooperative relaying communication systems model is proposed and this thesis study the performance of Multi-point relaying cooperative communication systems using selection decode-and-forward relays over independent non-identical Rayleigh fading channel. Exact and closed-form expressions of average symbol error rate (SER) and outage probability with Rayleigh fading channels was firstly derived by means of the moment generating function (MGF) with hyper-geometric function. Simulation results shown that the expressions were valid and the performance of two-hop multi-points cooperative relaying communication systems was better than that of traditional cooperative communication system. (2) Performance of cooperative relaying employs infrastructure based fixed relays having multiple antennas has been investigated. Close form expressions for outage probability and bit error rate have been derived for Nakagami fading channels. The effect of fading correlation among relay antennas and relay positioning on the system performance have also been studied.(3) The paper propose a base-station coordinated cooperative multi-user diversity incremental relaying protocol, which uses the broadcast feature of the wireless channel to induce multi-user diversity through a two-phase relaying process and improve throughout by saving the channel resource.