A Utility-based Resource Allocation Approach for the Downlink in CDMA Wireless Networks with Multimedia Services
ABSTRACT In this paper the problem of resource allocation for the downlink in code division multiple access wireless networks supporting multimedia services is addressed. A utility based power and rate allocation algorithm which aims at optimizing system's performance while satisfying multiple services' diverse quality of service (QoS) requirements is introduced and analyzed. For the efficient support of real-time users our proposed methodology takes into account their short-term throughput QoS constraints satisfaction, which is achieved by dynamically adapting their utility functions with respect to their corresponding short-term service performance information. Through modelling and simulation it is demonstrated that significant performance improvements are achieved in terms of the short-term throughput requirement satisfaction even for large number of real-time users, without any considerable loss in the total system's throughput.
- SourceAvailable from: ieeetmc.com01/1996; Kluwer., ISBN: 978-0-7923-9732-8
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ABSTRACT: We consider the following queueing system which arises as a model of a wireless link shared by multiple users. Multiple flows must be served by a "channel" (server). The channel capacity (service rate) changes in time randomly and asynchronously with respect to different flows. In each time slot, a scheduling discipline (rule) picks a flow for service based on the current state of the channel and the queues. We study a scheduling rule, which we call the exponential rule, and prove that this rule is throughput-optimal, i.e., it makes the queues stable if there exists any rule which can do so. In the proof we use the fluid limit technique, along with a separation of time scales argument. Namely, the proof of the desired property of a "conventional" fluid limit involves a study of a different fluid limit arising on a "finer" time scale. In our companion paper  it is demonstrated that the exponential rule can be used to provide Quality of Service guarantees over a shared wireless link.11/2001;
Conference Proceeding: Opportunistic scheduling policies for wireless systems with short term fairness constraints[show abstract] [hide abstract]
ABSTRACT: We consider a scheduling problem for packet based wireless systems with time-varying channel conditions. Designing scheduling mechanisms that take advantage of time-varying channel conditions, which are different for different users, is necessary to improve the wireless system performance. Such scheduling mechanisms are called opportunistic. In this paper we formulate an opportunistic scheduling problem with short term processor sharing fairness constraints as an optimization problem where short term refers to the time window on which the fairness is guaranteed. In its most general form, this problem cannot be solved analytically. We first solve the above optimization problem for three special cases. We consider the scheduling problem with long term fairness constraints; then we consider the scheduling problem for the shortest possible window under two sets of assumptions namely, one in which users have identically distributed channel conditions and another in which users have independent channel conditions. Observing the form of the corresponding optimal policies, we define a heuristic policy for our original opportunistic scheduling problem with short term fairness constraints. We show via simulation that our heuristic policy attains a good trade-off by guaranteeing short term fairness while achieving high average system throughput. We also illustrate that the optimal opportunistic scheduling policy with long term fairness constraint is in fact unfair in practical scenarios.Global Telecommunications Conference, 2003. GLOBECOM '03. IEEE; 01/2004