Resource Allocation for Delay Differentiated Traffic in Multiuser OFDM Systems

TL;DR

This paper addresses resource allocation in multiuser OFDM systems with mixed delay-sensitive and delay-insensitive traffic, proposing optimal and suboptimal algorithms to maximize throughput while guaranteeing delay constraints.

Contribution

It introduces a novel resource allocation framework for heterogeneous OFDM systems, including a multi-level water-filling solution and efficient algorithms for practical implementation.

Findings

Optimal power allocation follows a multi-level water-filling principle.

Proposed algorithms effectively balance throughput and delay guarantees.

Numerical results show improved performance in outage probability and transmission rates.

Abstract

Most existing work on adaptive allocation of subcarriers and power in multiuser orthogonal frequency division multiplexing (OFDM) systems has focused on homogeneous traffic consisting solely of either delay-constrained data (guaranteed service) or non-delay-constrained data (best-effort service). In this paper, we investigate the resource allocation problem in a heterogeneous multiuser OFDM system with both delay-constrained (DC) and non-delay-constrained (NDC) traffic. The objective is to maximize the sum-rate of all the users with NDC traffic while maintaining guaranteed rates for the users with DC traffic under a total transmit power constraint. Through our analysis we show that the optimal power allocation over subcarriers follows a multi-level water-filling principle; moreover, the valid candidates competing for each subcarrier include only one NDC user but all DC users. By converting this combinatorial problem with exponential complexity into a convex problem or showing that it can be solved in the dual domain, efficient iterative algorithms are proposed to find the optimal solutions. To further reduce the computational cost, a low-complexity suboptimal algorithm is also developed. Numerical studies are conducted to evaluate the performance the proposed algorithms in terms of service outage probability, achievable transmission rate pairs for DC and NDC traffic, and multiuser diversity.