Performance of Spectrum Sharing Protocol for Uplink Transmissions in Cellular Communications with Relays

In this paper, we consider a cellular communication system with half-duplex regenerative relays, and propose a dynamic spectrum access (DSA)-based protocol for simultaneous uplink transmission in the same frequency band as the downlink transmission. The proposed protocol facilitates better frequency utilization. In this protocol, relay selection is employed for the downlink, while distributed beamforming is used in the uplink. Assuming peak interference constraints as well as peak power constraints for all uplink transmissions, we analyze the outage performance of the protocol. Expressions are also presented for the asymptotic outage probability. Computer simulations demonstrate that asymmetry in rates that is characteristic of cellular links makes it possible to achieve good outage performance for both uplink and downlink transmissions.