Key Technology Research Of Wireless Network Cooperative Communication

Cooperative communication is a new transmission technology, and it is an important wayof practical MIMO technology, it combines diversity and relay transmission advantage, sotraditional centralized competitive relationship can turn to distributed cooperative relationship,the capacity and quality of communication can be improved by cooperative modes, thetechnical problems of multi-antenna on the sending terminal can be solved without changinginfrastructure, so it has caused the extensive concern of the academic field and telecomoperators. The cooperative communication key technologies include relay node selection,coding cooperation, energy consumption and optimal power allocation, multi-cellcollaboration and cross-layer cooperation. The first three problems among them are basic;these problems have researched in the dissertation as follows:It is a basis problem to select one or more nodes as cooperative node in the cooperativesystem. Firstly, in order to increase system reliability and reduce complexity, this dissertationput forward a relay selection strategy, at the same time, the reliable node can be determinedaccording to the SNR threshold method; the optimal node can be obtained by selection factor.The strategy has a low BER and complexity. Secondly, the relay selection on two-way systemwas reseached, two_way relay nodes selection strategy based on amplify forwarding andnetwork coding were proposed, moreover, two strategies can achieve the full diversity, and theBER performance and diversity gain of the two strategies are compared. Finally, in the multiS-R-D nodes network environment, the use of exhaustive algorithm can obtain the optimalsolution. In order to reduce its computational complexity, improved selection strategy hasproposed, the strategy can achieve throughput similar to optimal algorithm, and complexity isalso greatly reduced.Coding cooperation is combined with mature channel coding techniques and cooperativecommunications technology; it can not only provide spatial diversity gain and coding gain.Firstly, the hybrid cooperative model based on LDPC was proposed. Moreover, According tothe coherence among the symbols of the LDPC code words, send different parts of them bydifferent users, and obtain diversity gain and coding gain.secondly, the fountain codes have an advantages of a low degree of coding redundancy, and the sender does not need to considerthe state of the channel. A multi-relay cooperative model is proposed, and LT code applies init, furthermore, we discussed two transmission modes, the scheme have lower bit error rate, aswell as a faster decoding speed.In sensor networks, the node energy consumption and power distribution is also keyissues. Firstly, the dissertation has analysised the factors that affect the cooperative nodeenergy consumption, and energy consumption of several cooperative modes is compared. Onthe other hand, an algorithm based on energy efficient transfer (EET) was proposed, thealgorithm first calculate the critical path ratio threshold, and then put geometric relationship asjudged conditions, that is, to determine whether a node in the wireless network as cooperativenodes. Finally, the optimal power allocation problem of the cooperative modes is researched,from the perspective of the outage probability, researching optimum power allocationalgorithm and simulation, discussing the cooperative gain of optimum power allocation andequal power allocation, analyzing the relationship between various parameters.