The Power Allocation Research In Cooperative Communication System

Now the MIMO technology is becoming a research focus in wirelesscommunications. The MIMO technology can improve the performance of the system,but it's difficult to install multiple antennas on the mobile terminal as a result of theconstraint of the size and cost. So the constraints become the limit of the applicationof MIMO technology. Because of this condition, the cooperative diversity technologywas proposed. The cooperative diversity technology is that each single-antenna usersto send both its own information and its collaborative partners'information inmulti-user environment. Studies have shown that the cooperative diversity technologycan improve the transmission reliability without changing the number of the users'antenna.Compared with the traditional direct communication, the collaborationcommunication will take more time, frequency, power or other system resources. Inorder to maximize the power efficiency and minimize interferences among users, Thetransmit power should be reasonable allocation in the source node and relay node. Sothe power allocation technology becomes the key technology in the cooperativecommunication.This thesis focuses on the power allocation in the cooperative communication.The main content and the original techniques are as follow:In multi-relay wireless communication system, we studied the impact of powerallocation between the source node and each relay node on the system capacity. Byanalyzing the capacity of multi-relay cooperative communication systems withnon-regenerative cooperative relay mode, we propose a suboptimum power allocationalgorithm (SPAA) with low computational complexity. The results show that,compared with the water-filling power allocation algorithm(WFAA), the proposedalgorithm significantly reduces the computational complexity.In the classical three-node model, we studied the power allocation under thecondition of the maximum power limit and the symbol error rate. According to thesending node and relay node power and maximum power values of different sub-casesof optimal power allocation. According to the power and the maximum power valuesof the sending node and the relay node, Corresponding optimal power allocationalgorithm was proposed. In the case of a given node power lever, we discussed the system various parameters impact on the performance of the system. The results show that the high energy efficiency appear at the middle of the sending node and relay node. If the communication distance is shorter, the modulation will be higher and the energy efficiency will be higher.