Can One Achieve Multiuser Diversity in Uplink Multi-Cell Networks?

Abstract

We introduce a distributed opportunistic scheduling (DOS) strategy, based on two pre-determined thresholds, for uplink \(K\)-cell networks with time-invariant channel coefficients. Each base station (BS) opportunistically selects a mobile station (MS) who has a large signal strength of the desired channel link among a set of MSs generating a sufficiently small interference to other BSs. Then, performance on the achievable throughput scaling law is analyzed. As our main result, it is shown that the achievable sum-rate scales as \(K\log(\text{SNR}\log N)\) in a high signal-to-noise ratio (SNR) regime, if the total number of users in a cell, \(N\), scales faster than \(\text{SNR}^{\frac{K-1}{1-\epsilon}}\) for a constant \(\epsilon\in(0,1)\). This result indicates that the proposed scheme achieves the multiuser diversity gain as well as the degrees-of-freedom gain even under multi-cell environments. Simulation results show that the DOS provides a better sum-rate throughput over conventional schemes.