Multi-user Cooperation In Communication Networks And Performance

In wireless communications, multipath fading has been a deadly factor degrading the performance of communication until the advent of cooperative diversity technology. Cooperative diversity technology is a new type of distributed spatial diversity techniques, which, in recent years, has been valued highly by the experts, and become one of the key technologies of the Next-Generation Wireless Communication Networks. It is the core technology in the spectrum sensing and spectrum sharing in the field of cognitive radio systems in foreign.Several efficient cooperative diversity protocols, including Amplify-and-Forward (AF), Decoded-and-Forward (DF), Selection-and-Relay (SF) and Coded-Cooperative (CC), are now widely used.This paper first introduced the concept of cooperative diversity, compared to the performance of different protocols in terms of outage probability; Secondly, we discussed the outage probability and bit error rate performance under the DF protocols over the independent and identically distributed fading channels, obtained the general expression in the mixed channel for the two factors; Then we discussed the performance of the multi-user cooperative communication network, analyzed the outage probability and bit error rate performance in the single-user multi-relay system based on DF protocol, raised cooperative coding and adaptive cooperative coding in multi-user multi-relay networks, and confirmed the positive gains the later brings. Mean while, we built a multi-source multi-relay and multi-destinations system and raised a suitable solution. At last, with the adoption of cooperative diversity technology in the cognitive radio systems, it confirmed that cooperative diversity techniques can improve the sensitivity of the cognitive radio systems, and it can not only effectively enhance the spectral efficiency, but also can improve overall system throughput.