IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY, VOL. 55, NO. 5, SEPTEMBER 2006 1565 QoS-Aware Distributed Resource Management for a WCDMA Uplink Pratik Das, Student Member, IEEE, and Jamil Y. Khan, Senior Member, IEEE Abstract—In this paper, a hybrid resource management system for the uplink in Universal Mobile Telecommunications System wideband code-division multiple access (WCDMA) with compo- nents in the Node-B and user equipment (UE) has been proposed. A rate scheduler in the client focuses on average packet delays as a means of abstracting application-specific requirements from the rest of the resource management scheme. It controls uplink transmission through variable spreading gain to optimize resource usage while meeting target delays. Service change requests from the distributed rate schedulers are collectively processed through interservice and intraservice priority queuing in a manner that is shown to exhibit fairness in allocation of resources when cu- mulative load exceeds system capacity. The performance of the proposed algorithm is explored through discrete-event simulations for three classes of traffic, namely voice, video, and data, over the WCDMA uplink in the presence of short-term Rayleigh fading, automatic repeat request, forward error correction, target trans- mission delays to meet the respective quality of service, and frame error rate targets in a “multicell” environment. The authors an- alyze two alternatives for distributed resource management with the UE or Node-B in control of rate scheduling and observe the fairness in resource allocation of both systems. Priority of speech, video, and data traffic is respected and reflected in 95th percentile transmission delays for heavily loaded systems. Index Terms—Radio resource management (RRM), rate sched- uling, Universal Mobile Telecommunications System (UMTS), uplink, wideband code-division multiple access (WCDMA). I. I NTRODUCTION T HE POPULARITY of applications such as email, web browsing, streaming, and nonreal-time multimedia have led to tremendous growth in global communication over the Internet. Recently, “broadband” Internet access through dig- ital subscriber line (DSL), cable, and satellite networks has improved the diversity, quality, and quantity of media avail- able to the Internet user. This greater freedom in accessibility has led to a 155% compound annual growth rate (CAGR) in broadband penetration worldwide between 1999 and 2002, with forecasts predicting further acceleration in penetration as costs reduce [1]. The last decade has seen a push for research and development to bridge the gap between the quality of content accessible Manuscript received September 4, 2004; revised October 26, 2005 and January 25, 2006. This work was supported by the University of Newcastle, Callaghan, N.S.W., Australia. The review of this paper was coordinated by Dr. A. Chockalingam. The authors are with the School of Electrical Engineering and Computer Science, University of Newcastle, Callaghan, N.S.W. 2308, Australia (e-mail: pratik@ee.newcastle.edu.au; jkhan@ee.newcastle.edu.au). Digital Object Identifier 10.1109/TVT.2006.878738 over mobile systems and what is available over fixed networks. Third-generation (3G) and fourth-generation (4G) mobile com- munication technology aims to narrow this gap. The relevance of the mobile communication device and the need to provide services through it similar to those available on fixed networks have never been greater. At the end of 2003, there were over 1.35 billion mobile subscribers worldwide as compared with 1.2 billion fixed-line communications users [2]. It is known that different applications require different qual- ities of service (QoS) from underlying communication links and that traditionally circuit-switched transmission schemes have been used in wireless communications to guarantee QoS. However, with the bandwidth available being less than that required to meet demand in the licensed civilian wireless com- munication domain, and the high cost associated with spectrum ownership, bandwidth becomes the most valuable resource in such a scenario. In this context, the overallocation of resources for each circuit or call, i.e., the spectral inefficiency, becomes a significant demerit. Efficient use of bandwidth can be promoted through packet-switched data transmission because of the gain in throughput achieved when statistically multiplexing users according to their transmission loads and channel conditions. However, the QoS experienced by a user and the diversity in the link requirements of different applications must also be considered [3]. By maintaining application-specific service re- quirements while improving network throughput, QoS schemes stand as an enabling technology for the success of 3G systems. The Universal Mobile Telecommunications System (UMTS) is a 3G system in development within the Third-Generation Partnership Project (3GPP) with wideband code-division mul- tiple access (WCDMA) as the radio access mechanism. In this paper, we concentrate on resource management for the WCDMA uplink. UMTS provides a common channel and a dedicated channel (DCH) for uplink transmissions. While the former would support true packet-switched communication, the latter can be also used to provide packet-controlled commu- nication with similar statistical multiplexing gains because of the ability to throttle the transmission rate over time. UMTS enables different data rates for users in several ways, i.e., through variable spreading gain (VSG) per transmission chan- nel, through multiple codes (MC) with fixed spreading gain (FSG) transmitted in parallel, or a combination of the two [4]. However, for simplicity of implementation, most propose the use of one or the other. In terms of the signal-to-noise ratios (SNRs) and bit-error rates (BERs) experienced by users, both approaches have an identical effect on the system [5], [6]. The spreading gain or the number of codes allocated to users can also be scheduled differently at periodic intervals in UMTS. 0018-9545/$20.00 © 2006 IEEE