Cooperative Relay Performance Analysis And Enhanced Technology Research Over Nakagami-m Fading Model

Cooperation technology has been proposed to achieve high transmission rate and enhance reliability in the future wireless communication system. It can provide a stable quality of service (QoS) and transmission rate whether the users are in the center or the edge of the cell. The expansion of the BS (base station) coverage and the intergration of multiple wireless networks can be obtained obviously via cooperation technology, which is generally better than other technologies.The gain evaluation of cooperative relay technology performance is an important topic. The cooperative multi-relay channel model is proposed. The capacity of several relay protocols is analyzed and the factors which impact the capacity upper bound are obtained. These factors include power allocation scheme, the location and amount of relays, etc.The former researches of relay outage performance are exploited Rayleigh fading model. But the Nakagami-m distribution is able to characterize the fading channel characteristics better than Rayleigh fading model in actual wireless environment. The outage probability performance of decoded-and-forward (DF) and amplify-and-forward (AF) relay protocols is analyzed utilizing moment generating function (MGF) and inverse Laplace transform over Nakagami-m fading channel, and the asymptotic expressions of outage probability is derived. The application scenarios of DF and AF protocol are acquired.The heterogeneous cooperative relay technology can integrate various wireless networks. Considering the characteristics of heterogeneous cooperative relay channel, the heterogeneous cooperative relay channel models are presented. A theoretical analysis on the capacity of the heterogeneous cooperative relay channel is given, and it is compared with homogenous cooperative relay channel, in order to elaborate the advantages and disadvantages of the two different relay channels, as well as the applicable scenarios. A numerical example is given to describe how the power distribution and the location of the relay impact on the capacity of the relay channel. The outage probability performance of heterogeneous cooperative relay is analyzed over Nakagami-m fading model. The impact of relay amount on the outage performance in different scenarios and distinguish the differences of heterogeneous and homogeneous systems.An adaptive-forward relay protocol is proposed considering the lack of feedback channel situation. The outage probability performance of this protocol is analyzed utilizing moment generating function and inverse Laplace transform in fading channel, and the asymptotic expressions of outage probability is derived. It is compared with the informed DF and AF relay protocols. And the application scenarios of these relay protocols are acquired. The impact of relays amount on the system performance are further analyzed. According to these results, the advantages and characteristics of this protocol are confirmed.A hierarchical cooperative broadcast system model with superposition coding is proposed according to the characteristics of wireless broadcast system. The performance of cooperative relay system adopoted superposition coding is analyzed. And the impacts of system parameter on the system performance are further analyzed. The outage performance of cooperative relay system adopoted superposition coding over Nakagami-m fading model is futher analyzed and the asymptotic expressions of outage probability is derived. The impact of relay location and the power allocation scheme on the outage performance is given.