Optimal power allocation and relay selection for multiple code division multiple access peer-to-peer communication

Аннотация

The authors consider a half-duplex asynchronous code division multiple access cooperative network with N source–destination (SD) pairs and a number of relay nodes where the nodes of all pairs have to exchange data in two hops via assistance of one of the available relays. In this study, they minimise the total transmit power and derive the closed-form solution for choosing the best relay, the best relay gain and the transmit powers of all sources where some predefined signal-to-interference plus noiseratios (SINRs) are guaranteed. Interestingly, the feasibility condition of the problem depends only on the required SINRs, the number of SD pairs and the maximum cross-correlation of users’ codes. They suggest two control procedures for admitting or dropping of users to the network to satisfy the feasibility condition. For a reciprocal environment, the best relay and its gain are proved to remain unchanged for reversing the communication directions. In addition, the authors’ power control algorithm can be directly applied to the case of two-hop two-way relaying. Computer simulations are used to demonstrate the system performance.