Research Of Selection Cooperation Transmission Technology In Wireless Networks

Cooperative communication technology can take the full advantages of antenna resources in wireless systems, which allows single-antenna systems to reap the benefits of multiple-input multiple-output(MIMO) systems. Thus, it can significantly improve both the anti-fading performance and the reliability of data transmission. As one of the main methods of cooperation communication, selection cooperation can achieve full diversity order by choosing just one relay with the best channel value to perform cooperation. Hence it has received much attention from academia due to its high performance and low complexity. In the literature of selection cooperation, most works concentrate on relay-destination channels to exploit available gains as far as possible. Meanwhile, the analysis of selection cooperation has largely focused on the idealistic assumption that the number of available relays is deterministic.Considering the limitations mentioned above, this thesis focuses on the investigation of selection cooperation in terms of the utilizing of relay-relay channels and the varying number of relays. The main works of this thesis are as follows:Firstly, study the key relay mechanisms used in cooperation communication, and explore the development and the relay selection strategies of selection cooperation.Secondly, aiming at the limitation that common selection cooperation methods largely focus on the relay-destination channels to perform cooperation, a selection cooperation protocol with additional consideration about available relay-relay channels is proposed. By using feedback mechanism reasonably, the cooperative system can utilize both the relay-destination links and relay-relay-destination links to perform cooperation flexibly. The outage probability of the proposed protocol is analyzed from the perspective of information theory, and the analytical results are verified by numerical results.Thirdly, considering the limitation that most of the analytical results were derived based on the idealistic assumption of a fixed number of available relays, this thesis analyzes the performance of selection cooperation with dynamically changing relay number. By modeling the occupancy of each relay as a Markov on-off chain in a two-hop network with multi-relays, a close-form expression for outage probability is derived, and the theoretical derivation is demonstrated by numerical results.Finally, based on the existing IEEE 802.15.4 network platform, the proposed protocol is realized and corresponding experimental platform for the proposed protocol is established. The test results demonstrate that the proposed protocol can enhance the reliability of data transmission significantly.This thesis investigates the selection cooperation transmission technology from the perspective of theoretical analysis and experimental tests, which has the better reference value for the practical application of selection cooperation in wireless systems.