Performance And Power Allocation Research For Cooperative Communication Systems

Cooperative communication is an emerging technology which is based on the existing network topology and has the ability to improve radio spectrum utilization together with system power efficiency through the multi-user collaboration. The technology implements and supports higher rates, higher bandwidth and wider network coverage through resources of the frequency, time, space, multi-dimensional effective multiplexing. Now the technology has become the key one of wireless communications B3G/4G.This paper analyzes the system performances and power allocation schemes under some kinds of model and protocols for cooperative communication systems. In addition, we also study the combination of cooperation and cognitive radio such as modeling and performance analyzing of cognitive and cooperative communication systems.The symbol error rate (SER) performance is analyzed for the optimization of amplify-and-forward (AF) multi-node cooperative communication systems in the third chapter. Firstly, theory SER is analyzed for the systems. Then, the corresponding low bound (LB) is derived, that will be nearing the theory SER between both low and high signal-to-noise ratio conditions. Finally, algorithms used in optimal power allocation (OPA) and partnership selection for the systems by exploring the LB as cost function are formulated. Theoretical analysis and simulation results show that the OPA outperforms traditional EPA in SER performance. Moreover, the LB will be more nearing the theory SER than existing algorithms especially under low SNR conditions.In the fourth chapter optimal relay and cooperation opportunity are analyzed for the outage performance optimization of decode-amplify-forward (DF), selective DF and incremental SDF (ISDF) in multi-node MIMO cooperative communication systems. Firstly, the system model for the proposed multi-node MIMO cooperative protocol is analyzed. Then, the optimal relay selection strategy (routing) is proposed. The mutual information and outage probability between source and destination nodes for the proposed scheme are formulated with the relays have the capability of maximum ratio combining (MRC) receiving and beam-forming transmitting. We proved that the outage performance for the proposed algorithm is the low bound for the general SDF/ISDF. Finally, we discussed the optimal power allocation and cooperation opportunity.The chapter?is divided into two sections. The first one analyzed the outage, throughput performance and power allocation for CR MIMO systems. The main contributions are the derivation of the outage and throughput closed-form expressions for licensed and cognitive users in both ideal and real cognitive MIMO flat Rayleigh fading environments. Under the condition of "transparent" from cognitive user to licensed user and random licensed user package arrivals, the paper analyzed the power allocation algorithm and the throughput then derived the optimal power allocation (OPA) algorithm for CR MIMO systems. Numerical results verified the theory analyses and the results show that the OPA algorithms maximize the maximum average throughput both for the licensed users and cognitive users while guarantees stability of the whole systems. For comparing, we also simulate SISO system under the same conditions.The second one studied the performance gain of asymmetry Cognitive Radio (CR) interference communication systems which is combined with amplify-and-forward (AF) cooperation technology. The main contributions are the derivation of outage and throughput closed-form expressions for licensed and cognitive users in cognitive cooperative communication systems under flat Rayleigh fading channel. Under the condition of "transparent" from Cognitive User (CU) to Licensed User (LU) and random LU package arrivals, the paper analyzed the power allocation algorithm and the throughput for the CU and derived the optimal power allocation (OPA) algorithm for cognitive cooperative communication systems. Simulation and analyzing show that the cooperation technology and OPA increase the overall system performance for both licensed and cognitive users while guarantee stability of the LU systems.