LAUSR

We design user-assisted relaying strategies and analyze their performance in a multiple-input-multiple-output uplink cellular network. In user-assisted relaying, the base station serves an active user equipment (UE) using a transmission scheme adaptive between direct transmission and relaying via another UE according to a cooperation strategy. Modeling the network based on stochastic geometry and Poisson point processes, we propose a practical, geometric-based cooperation strategy determining how to select the relaying UE and when to perform relaying transmission. The proposed relaying transmission employs a simple transmit beamforming and one of two optimized receive combining schemes depending on interference awareness. The extra interference generated by relaying UEs is captured in an interference model that accounts for the adaptive transmission and random locations of these UEs. Integrating the proposed cooperation strategy, transmit and receive beamforming design, and interference model, we analyze the network outage rate performance. Provided sufficient density of potential relay UEs, results demonstrate user-assisted relaying to be most beneficial for cell edge UEs when the relaying UEs are equipped with multiple antenna elements and their signals propagate in relatively high shadowing environments.