Throughput analysis of link adaptation in interference-limited cellular systems

Abstract

We analyze the throughput performance of a link adaptation scheme in which a user, based on his SIR estimate, chooses an appropriate modulation and coding scheme. We consider the scenario where the users face similar path loss and fading models, and always have packets to transmit. The impact of link adaptation thresholds and channel correlation on the system throughput is investigated for a co-channel interference-limited TDMA cellular network. An expression for system throughput is derived in terms of the basic system parameters: channel fade statistics, number of users per cell, and link adaptation thresholds. We show that the optimal thresholds that maximize system throughput do not depend on the channel correlation. This behavior is very different from the stable queues scenario where the channel correlation was shown to be a crucial parameter in determining the impact or the no-transmission mode on system performance. It explains, to some extent, the intuition behind the heuristic formulae proposed in the literature.