Throughput Region of Spatially Correlated Interference Packet Networks

TL;DR

This paper introduces opportunistic random access protocols for wireless networks that leverage interference pattern knowledge and spatial correlation to improve throughput, contrasting with traditional collision-based methods.

Contribution

It develops and proves the optimality of new protocols that utilize interference patterns and spatial correlation, including capacity characterization of correlated interference channels.

Findings

Spatial correlation can make outdated feedback as effective as real-time feedback.

Feedback's impact on throughput varies with spatial correlation regimes.

The protocols outperform conventional collision-based methods under certain conditions.

Abstract

In multi-user wireless packet networks interference, typically modeled as packet collision, is the throughput bottleneck. Users become aware of the interference pattern via feedback and use this information for contention resolution and for packet retransmission. Conventional random access protocols interrupt communication to resolve contention which reduces network throughput and increases latency and power consumption. In this work we take a different approach and we develop opportunistic random access protocols rather than pursuing conventional methods. We allow wireless nodes to communicate without interruption and to observe the interference pattern. We then use this interference pattern knowledge and channel statistics to counter the negative impact of interference. We prove the optimality of our protocols using an extremal rank-ratio inequality. An important part of our contributions is the integration of spatial correlation in our assumptions and results. We identify spatial correlation regimes in which inherently outdated feedback becomes as good as idealized instantaneous feedback, and correlation regimes in which feedback does not provide any throughput gain. To better illustrate the results, and as an intermediate step, we characterize the capacity region of finite-field spatially correlated interference channels with delayed channel state information at the transmitters.