Improving Voice and Data Service Provisioning in Cellular/WLAN Integrated Networks by Admission Control.
Wei Song, Yu Cheng, Weihua Zhuang, Aladdin Saleh · 2006
In this paper, we study the voice and data service provisioning in an integrated system of cellular and wireless local area networks (WLANs). To maximize the overall resource utilization of the integrated system, complementary quality of service (QoS) support capabilities of the two networks are exploited to serve voice and data traffic. As an essential resource allocation aspect, admission control can be used to properly admit voice and data calls to the overlaying cellular cells and WLANs. In this study, a generalized admission scheme is analyzed to investigate the dependence of resource utilization on admission parameters, which vary with user mobility and traffic variability. By applying an effective QoS evaluation approach, the admission parameters can be determined using a search algorithm. I. INTRODUCTION With complementary characteristics presented in the cellu- lar network and wireless local area network (WLAN), their interworking becomes a promising trend for next-generation wireless networks (1). The cellular network provides ubiqui- tous coverage, while WLANs are deployed disjointly in hot- spot areas. In the area with WLAN coverage (referred to as double-coverage area in the following), both cellular and WLAN accesses are available. With this two-tier overlaying structure, a new call in the double-coverage area can be admitted either to a cell or WLAN. Proper admission decision is also needed for vertical handoffs between a cell and WLAN, which is not necessary to maintain a call but mainly for load balancing and/or quality of service (QoS) improvement. The heterogeneous underlying QoS support of the integrated network can be exploited to maximize the resource utilization. In the cellular network, the base station (BS) controls access to the shared radio spectrum and reserves resources for admitted calls. The centralized control and reservation-based resource allocation enables fine-grained QoS. On the other hand, the medium access control (MAC) in WLANs is usually contention-based, e.g., the distributed coordination function of IEEE 802.11. Because of inevitable collision and backoff, this type of MAC is difficult to support services with strict QoS requirements such as real-time voice service, although it is efficient in serving bursty data traffic. With the complemen- tary QoS support, multi-class traffic load should be properly distributed to the cells and WLANs by admission control. Two admission schemes are discussed in (2,3) for voice and data services in a cellular/WLAN integrated network. In this paper, we further generalize the above admission schemes and investigate the dependence of resource utilization on admission