Collision Helps - Algebraic Collision Recovery for Wireless Erasure Networks

TL;DR

This paper introduces an algebraic collision recovery method for wireless erasure networks that leverages linear algebra to decode collided packets, improving delay and throughput over traditional collision avoidance techniques.

Contribution

It presents a novel algebraic collision representation and an ACK mechanism that enhances decoding capabilities and network performance in wireless erasure networks.

Findings

Outperforms ALOHA and centralized scheduling in delay and throughput.

Achieves stability region matching the cut-set bound for streaming arrivals.

Enables decoding from collisions using linear algebra and network coding.

Abstract

Current medium access control mechanisms are based on collision avoidance and collided packets are discarded. The recent work on ZigZag decoding departs from this approach by recovering the original packets from multiple collisions. In this paper, we present an algebraic representation of collisions which allows us to view each collision as a linear combination of the original packets. The transmitted, colliding packets may themselves be a coded version of the original packets. We propose a new acknowledgment (ACK) mechanism for collisions based on the idea that if a set of packets collide, the receiver can afford to ACK exactly one of them and still decode all the packets eventually. We analytically compare delay and throughput performance of such collision recovery schemes with other collision avoidance approaches in the context of a single hop wireless erasure network. In the multiple receiver case, the broadcast constraint calls for combining collision recovery methods with network coding across packets at the sender. From the delay perspective, our scheme, without any coordination, outperforms not only a ALOHA-type random access mechanisms, but also centralized scheduling. For the case of streaming arrivals, we propose a priority-based ACK mechanism and show that its stability region coincides with the cut-set bound of the packet erasure network.