Opportunistic scheduling policies for improved throughput guarantees in wireless networks

Jawad Rasool,Geir E Øien,Vegard Hassel,Sébastien De La Kethulle De Ryhove

doi:10.1186/1687-1499-2011-43

Abstract

Offering throughput guarantees for cellular wireless networks, carrying real-time traffic, is of interest to both the network operators and the customers. In this article, we formulate an optimization problem which aims at maximizing the throughput that can be guaranteed to the mobile users. By building on results obtained by Borst and Whiting and by assuming that the distributions of the users' carrier-to-noise ratios are known, we find the solution to this problem for users with different channel quality distributions, for both the scenario where all the users have the same throughput guarantees, and the scenario where all the users have different throughput guarantees. Based on these solutions, we also propose two simple and low complexity adaptive scheduling algorithms that perform significantly better than other well-known scheduling algorithms. We further develop an expression for the approximate throughput guarantee violation probability for users in time-slotted networks with the given cumulants of the distribution of bit-rate in a time-slot, and a given distribution for the number of time-slots allocated within a time-window.

Highlights

In modern wireless networks, opportunistic multiuser scheduling has been implemented to obtain a more efficient utilization of the scarcely available radio spectrum
We focus on the throughput guarantee violation probability (TGVP) because a throughput guarantee in most cases cannot be given with absolute certainty, i.e., we are focusing on soft throughput guarantees
We focus on the TGVP here since a throughput guarantee in most cases cannot be given with absolute certainty

Summary

Introduction

Opportunistic multiuser scheduling has been implemented to obtain a more efficient utilization of the scarcely available radio spectrum. For wireless cellular standards, such as 1 × EVDO, HSDPA, and Mobile WiMAX [1], the scheduling algorithms are often not specified in the standardization documents. Selecting the most efficient scheduling algorithms will be critical for having the most efficient utilization of a wireless network; the vendors that implement the most-suited scheduling algorithms will have a competitive advantage. Opportunistic multiuser scheduling will give higher throughput in a wireless cell than non-opportunistic algorithms like Round Robin (RR) because priority is given to the users with the most favorable channel conditions [2,3]. Always selecting the users with the best channel quality may lead to starvation of other users

Objectives

Findings

Discussion

Conclusion