An Advanced Tree Algorithm with Interference Cancellation in Uplink and Downlink

TL;DR

This paper introduces ATIC, an advanced tree algorithm with interference cancellation capabilities at both the access point and user levels, significantly improving throughput and reducing delays in collision resolution.

Contribution

ATIC extends existing tree algorithms by enabling users to perform interference cancellation, achieving higher throughput and efficiency in collision management.

Findings

Achieves asymptotic throughput of 0.924 with many users

Reduces collision occurrences and packet delays

Requires additional feedback resources compared to other algorithms

Abstract

In this paper, we propose Advanced Tree-algorithm with Interference Cancellation (ATIC), a variant of binary tree-algorithm with successive interference cancellation (SICTA) introduced by Yu and Giannakis. ATIC assumes that Interference Cancellation (IC) can be performed both by the access point (AP), as in SICTA, but also by the users. Specifically, after every collision slot, the AP broadcasts the observed collision as feedback. Users who participated in the collision then attempt to perform IC by subtracting their transmissions from the collision signal. This way, the users can resolve collisions of degree 2 and, using a simple distributed arbitration algorithm based on user IDs, ensure that the next slot will contain just a single transmission. We show that ATIC reaches the asymptotic throughput of 0.924 as the number of initially collided users tends to infinity and reduces the number of collisions and packet delay. We also compare ATIC with other tree algorithms and indicate the extra feedback resources it requires.