Random Access OFDMA Network with Dynamic Resource Allocation Using Regenerative Decode and Forwarding Protocol with Rayleigh Fading Channel

In this paper we have investigated the optimum power allocation in a random access wireless orthogonal frequency division multiple access (OFDMA) communication system with multiple source and multiple destination nodes. The multiple sources in the system each transmitted information to multiple destinations and cooperated via an orthogonal regenerative decode and forward protocol with different frequency slots. We developed a framework for power allocation in this scenario around the concept of OFDMA and derived the expressions for the transmit power received by each source as a function of the cooperation ratio between sources. The relay node employing orthogonal regenerative decode and forwarding strategy with optimum power allocation helped the source nodes that had low quality direct links and had destination near to the relay first and improved the individual capacities of the low potential source node. We investigated the effect of interference when all sources transmit with equal frequency allocation and the impact of orthogonal frequency division among the sources. In the case of Rayleigh fading channels, we demonstrated that mutual cooperation can minimize the average total required transmit power and can also lead to a reduction in average required transmit power when both the sources have symmetric and asymmetric fading channels to the destinations.