Cooperative Diversity in Wireless Networks

An ad-hoc network with a base station, a mobile and a third station acting as a relay is analysed. The channels are modelled using path loss, Rayleigh fading and thermal noise. Different combining methods and diversity protocols are compared. In the simulations, the amplify and forward protocol shows a better performance than the decode and forward protocol. To combine the incoming signals the channel quality should be estimated as well as possible. Information about the average quality shows performance benefits, and a rough approximation about the variation of the channel quality increases the performance even more. Whatever combination of diversity protocol and combining method is used, second level diversity is observed. The relative distances between the relay and the stations has a large effect on the performance.