Research On The Relay Choice And The Power Allocation In Cooperative Diversity System

With the high speed development of the wireless mobile communication technology,people’s requirements are constantly improved for wireless communication rate and reliability.The multipath will have serious intersymbol interference. Therefore, how to overcome themultipath effect is first solve the problem to improve the communication quality. IEEE802.16standards mentioned in the single carrier frequency domain equilibrium (SC/FDE) technologycan effectivly against the channel’s frequency selective decline and realize high speed andhigh capacity transmission. On the other hand, IEEE802.16a standard suggests to combine theSC/FDE technology and MIMO technology to gain higher diversity gain with low complexity.But MIMO technology is difficult to practical in cellular nets and Ad-hoc and other network.The diversity cooperation finds a new way to application MIMO technology in small mobileterminal that is a promising spatial diversity technology.At the same time, there are many alternative potential available relay nodes in thecooperation communication system of many users. Relay choice is to select the mostappropriate node to participate cooperation communication process in these users to get thebiggest cooperation gain. Therefore, relay choice is an important problem in cooperationcommunication system. Another important question is the power allocation of cooperationcommunication system. It confirm some standards according to the different transmissionscheme under the premise of limited resources in the system. it can adaptivly distributereasonable power for every link in the constraint condition that can greatly improve theutilization rate of power, the communication system capacity and the anti-interferenceability.so they make the system more optimum performance.This article mainly studies achieve project of the SC/FDE technology and cooperationdiversity technology. Then it researches relay choice technology and power allocationtechnology, because the two technologies are important in the system. First, the relay choice,First it studies relay selection technology-opportunity relay that it is based on channelinstantaneous state information. Then it studies relay selection technology based on channellocation information and confirms the best relay position in the system. The experimentproved that choose the best relay to participate in cooperation communication that can reduce the system BER. Second, power allocation. The paper proposes power allocation optimizationalgorithm based on the minimum system error symbols rate and maximum system channelcapacity. Experiments show that adopting the two optimization algorithm can respectivelyreduce the system error symbols rate and increase the system channel capacity.