Application of Closed Loop Resource Allocation for High Data Rate Packet Transmission

Abstract

High data rate (HDR) CDMA systems are designed for cellular data distribution networks with maximized overall throughput and quality of service (QoS). Both figures of merit rely critically on the adoption of highly performant medium access control (MAC) algorithms, which are the focus of this paper. In particular, the closed loop resource allocation (CLRA) MAC algorithm for the reverse link of an HDR system is described. CLRA entails different properties and advantages that make it attractive for application in HDR or similar mobile Internet networks. First of all, CLRA is a macro control loop with distributed intelligence stimulated by busy tones issued by the base stations to inform terminals about their current load. Rate allocation is performed at terminals, whereby fairness is ensured by a stochastic rate assignment algorithm based on data queue states, rate history, and minimum rate guarantee. Network stability is guaranteed by controlled ramping driven by base stations busy tones. Further, a specific feature is introduced to account also for possible effects on base stations which are not in the rake active set; this feature is identified as candidate set protection. Finally, power headroom margins are used to minimize the occurrence of outage events. The analytical characterization of this MAC algorithm is derived using Markov chain modeling, and the results confirm the CLRA robustness, fairness and efficiency. The proposed algorithm is applicable to the 1xEV-DO system standardized by 3GPP2 within the cdma2000 family.