Understanding the Impact of Interference on Collaborative Relays

Collaborative relays achieve the benefits of spatial diversity without requiring physical antenna arrays at the end devices. Although many studies have demonstrated its effectiveness in an isolated single source-destination system, applying cooperative relays to a large-scale wireless network remains challenging. We show that a large wireless system with cooperative relays can be penalized by the elevated level of interference it produces. By examining the interdependency between interference management and cooperative relay strategies, the penalty is modeled by an increase in spectrum resource usage and translated into a penalty on single-link throughput. This throughput penalty serves as a reference for designing collaborative relays in isolated scenarios. To mitigate the impact of interference, we present two channel allocation mechanisms for collaborative relay systems with different fairness and utilization trade-offs. Simulation results confirm our analytical findings and demonstrate the effectiveness of our proposed channel allocation mechanisms.