Optimal Outage Performance In Cooperative Relaying Wireless Communication Networks

With the rapid development of the wireless communications technology, the wirelesscommunications will need higher transmission rate and more reliable transmission link inthe future while maintaining a satisfactory quality of service. But some small mobiledevices do not readily equip with a plurality of antennas, only with a single antenna.Therefore, cooperative relay network has been proposed to overcome this drawback andcooperative relay network can obtain spatial diversity. In cooperative relay network, theinappropriate power allocation can make the cooperative relay network to improve theperformance of the users and relays effectively. The thesis studies power allocationscheme for one-way and two-way cooperative relay network and relay selection, andpresents the corresponding power allocation strategy. Then, the idea of the cooperationamong the users will be introduced into cognitive radio network, and design the optimalpower allocation scheme.Firstly, this thesis introduces the cooperative communication mode and cooperativecommunication system model. In AF, DF and HDAF mode and different channelenvironment, it makes the target of the outage probability minimum by considering theoptimal power allocation scheme. Lagrangian multiplier method can be chosen tooptimize the corresponding solutions and it is concluded the optimal power value. At thesame time, the performance of the cooperative communication system will be analyzedunder the three cooperative approaches, and the performance of the three cooperative relaymodes will be compared by the numerical simulation analysis.Then, considering the physical network coding mode and power price, and anoptimal power allocation scheme based on two-way relay network is presented. It canachieve the outage probability of the system minimum under the power cost constraints ofsystem.The performance with considering power price compare with the performancewithout considering the allocation of power price. Simulation results show the proposedscheme decrease the outage probability of the two-way relay networks. Finally, in order to make the utilization of the wireless communication networkresources promoted, the idea of the cooperative communication between users will beconsidered. And we mainly concern the power allocation and the best relay selectionscheme in cooperative cognitive radio network. The perfromance of the cooperativecognitive radio network of the three cooperative modes will be analyzed under the averageinterference constraint and peak interference constraint while maintaining the interferencepower at primary user under a certain level. Simulation results show average interferenceconstraint has lower outage probability compared with the peak interference constraint,due to the adaptive transmission terminals and relay power. In addition, by comparingwith the three cooperative approaches, the performance of using ahybrid-decode-amplify-forward collaborative approach is better than the other twocollaborative ways, and the performance of using amplify-forward mode is better thandecode-forward mode.