Cooperative Transmission Using Incremental Opportunistic Relaying Strategy And Power Allocation

Cooperative diversity is a new kind of space diversity technology, the user's antenna and its partner's antenna constitutes a virtual multi-antenna array, and spatial diversity is achieved. Various results show that cooperative diversity can combat fading effectively, higher the data rate, lower the outage probability of service, increase the capacity of communication, and increase the Quality of Service and reliability.To enhance the performance of the cooperative communication system, study and analysis of several cooperative diversity protocols and relay selection methods are made. The main results obtained and contents of this thesis are as follows: the fundamental principle of diversity and cooperative diversity; the current cooperative diversity protocols and the comparison of them; the current relay selection schemes used in cooperative diversity and the comparison of them. Based on Opportunistic Relaying, a new collaborative communications program-- Incremental Opportunistic Relaying is researched. Theoretic and simulation analyses show that, in Incremental Opportunistic Relaying, the relay node doesn't forward information, and lower the outage probability of service. In addition, the optimal power allocation algorithm aiming at minimizing the outage probability is researched in this thesis under the condition that the system resources are limited in this program. The algorithm depends on the average channel information of the relays, without updating in real-time transmission, thus incurs little overhead. Simulation results show that, the performance of the optimal power allocation algorithm given in this thesis is very close to the performance of the exhaustive search method. Compared with equal power allocation algorithm, this algorithm can reduce the outage probability of cooperative communication.