A Fault-Tolerant Dynamic Channel Allocation Scheme for Enhancing QoS in Cellular Networks ∗ Jianchang Yang, D. Manivannan and Mukesh Singhal Computer Science Department University of Kentucky Lexington, KY 40506. email: {jyang2, mani, singhal}@cs.uky.edu Abstract In cellular networks, it is vital to allocate communica- tion channels efficiently because the bandwidth allocated for cellular communication is limited. When mobile hosts move from one cell to another cell, to provide uninterrupted service, the new cell should have enough channels to sup- port the ongoing communication of the mobile hosts that moved into the cell. If channels are statically allocated, as is the case in current cellular networks, a cell may run out of channels when large number of mobile hosts move to a cell, thus degrading the quality of service. To over- come this problem, dynamic channel allocation approaches have been proposed. Under dynamic channel allocation, channels are allocated to cells on demand, thus increasing channel utilization and hence improving the quality of ser- vice. Such channel allocation approaches fall under two categories, namely, centralized and distributed. Central- ized approaches are neither scalable nor reliable, while dis- tributed approaches have the potential to be both reliable and scalable. In this paper, we present a distributed dy- namic channel allocation scheme for cellular networks that is fault tolerant. Our approach can tolerate the failure of mobile nodes as well as static nodes and enhance the qual- ity of service by making efficient reuse of channels. Key words: distributed channel allocation, cellular networks, fault tolerance, cellular communication ∗ This research was supported in part by UK LAN NSF/EPSCoR Grant and the National Science Foundation CAREER Award # CCR -9983584 1 Introduction In cellular communication networks, the geographical area is di- vided into smaller regions, called cells [8]. In each cell, there is one Mobile Service Station (MSS) [13, 14] which serves the Mo- bile Hosts (MHs) present in the cell. A Mobile Host can com- municate with other Mobile Hosts in the system only through the Mobile Service Station in its cell, even if the Mobile Hosts are in the same cell. This kind of architecture was first proposed in [9], and is shown in Figure 1. MSS MSS MSS MSS MSS MH MH MH MH MH MH MH MH MH MH MH MH FIXED NETWORK MSS MH MH MH MH MH MH MH MH MH CELL CELL CELL CELL CELL CELL Figure 1. A model of wireless communication network Before a mobile host can communicate with another mobile host, the MSS in the cell should allocate a channel to support the communication. We assume that there are two types of channels available in the system, namely, communication channels and con- trol channels.A Communication channel is used to support com- munication between MH and MSS; while control channels are set aside to be used exclusively to send control message generated by the channel allocation algorithm. In this paper, henceforth, unless Proceedings of the 36th Hawaii International Conference on System Sciences - 2003 0-7695-1874-5/03 $17.00 (C) 2003 IEEE 1