Policy-Based QoS-Aware Packet Scheduling for CDMA 1x Ev-DO

Abstract

Abstract-CDMA 1x Ev-DO is an evolution of the CDMA2000 3G wireless standard to enable high rate packet data services up to 2.4Mbps in Rev 0, 3.1Mbps in Rev A, and 4.9Mbps in Rev B. To support such high data rates, CDMA 1x Ev-DO utilizes TDMA technology on the downlink allowing a single receiver per time slot. Accordingly, a scheduling algorithm is necessary to determine which user receives data in a given time slot. Typically, schedulers consider efficiency (increasing network throughput) or fairness (fair allocation of resources among users) as the basis for scheduling. To realize a reasonable tradeoff between efficiency and fairness, opportunistic schedulers have been proposed that take advantage of instantaneous improvements in users radio conditions by serving them at higher rates. However, given the increasing demand to support user QoS requirements, a QoS-aware scheduler may need to serve users even at times of inadequate radio conditions. In this paper, we propose a QoS-aware packet scheduling algorithm that takes into account policy rules that govern the relationships between different user QoS classes. Our scheduler uses marginal utility functions defined to embody the given rules when selecting users to be served on the downlink. Our scheduling algorithm is implemented in the OPNET module of the CDMA 1x Ev-DO system that we have developed, and its performance is compared to other scheduling algorithms. The simulation results show that our scheduler performs well ensuring the policy rules are followed, meeting users' QoS requirements, and providing fairness among users within the same QoS class.