Resource Allocation for Downlink Channel Transmission Based on Superposition Coding

TL;DR

This paper proposes a superposition coding-based resource allocation algorithm for downlink wireless channels, demonstrating significant throughput improvements over traditional time-sharing methods through numerical analysis.

Contribution

It introduces a novel power allocation algorithm for superposition coding in multi-user downlink channels, enhancing fairness and throughput tradeoffs.

Findings

Superposition coding outperforms time-sharing with 20-300% rate increase.

The proposed algorithm effectively balances fairness and throughput.

Numerical examples validate the efficiency of the superposition coding approach.

Abstract

We analyze the problem of transmitting information to multiple users over a shared wireless channel. The problem of resource allocation (RA) for the users with the knowledge of their channel state information has been treated extensively in the literature where various approaches trading off the users' throughput and fairness were proposed. The emphasis was mostly on the time-sharing (TS) approach, where the resource allocated to the user is equivalent to its time share of the channel access. In this work, we propose to take advantage of the broadcast nature of the channel and we adopt superposition coding (SC)-known to outperform TS in multiple users broadcasting scenarios. In SC, users' messages are simultaneously transmitted by superposing their codewords with different power fractions under a total power constraint. The main challenge is to find a simple way to allocate these power fractions to all users taking into account the fairness/throughput tradeoff. We present an algorithm with this purpose and we apply it in the case of popular proportional fairness (PF). The obtained results using SC are illustrated with various numerical examples where, comparing to TS, a rate increase between 20% and 300% is observed.