Maximum Sum Rate of Slotted Aloha with Successive Interference Cancellation

TL;DR

This paper analyzes the maximum sum rate of slotted Aloha networks using Successive Interference Cancellation (SIC), comparing ordered and unordered SIC, and evaluates their performance relative to traditional models across different SNR levels.

Contribution

It extends previous work by incorporating SIC receivers into the analysis of slotted Aloha, deriving optimal parameters and quantifying the rate gains and limitations at various SNR regimes.

Findings

Ordered SIC yields significant rate gains at moderate SNR.

At high SNR, rate gaps between models diminish, all sharing a slope of e^{-1}.

Multipacket reception improves sum rate performance compared to collision models.

Abstract

This is a sequel of our previous work [8] on characterization of maximum sum rate of slotted Aloha networks. By extending the analysis to incorporate the capacity-achieving receiver structure, Successive Interference Cancellation (SIC), this paper aims to identify the rate loss due to random access. Specifically, two representative SIC receivers are considered, i.e, ordered SIC where packets are decoded in a descending order of their received power, and unordered SIC where packets are decoded in a random order. The maximum sum rate and the corresponding optimal parameter setting including the transmission probability and the information encoding rate in both cases are obtained as functions of the mean received signal-to-noise ratio (SNR). The comparison to the capture model shows that the gains are significant only with the ordered SIC at moderate values of the mean received SNR $\rho$. With a large $\rho$, the rate gap diminishes, and they all have the same high-SNR slope of $e^{-1}$, which is far below that of the ergodic sum capacity of fading channels. The effect of multipacket reception (MPR) on the sum rate performance is also studied by comparing the MPR receivers including SIC and the capture model to the classical collision model.