A distributed access control method for wireless LANs in shadowing environments

In recent, years, the trend to use wireless LANs to realize mobile or ad ho c network is expanding. Previous proposals for access control methods for w ireless LANs included such methods as Carrier Sense Multiple Access with Co llision Avoidance (CSMA/CA) and polling. However, both methods have problem s of transfer efficiency and delay time. Research and development on new ac cess control methods is required to implement high-performance wireless LAN s. In this paper, we examine the development of a wireless version of the w ired token passing LAN access control method as a new wireless LAN access c ontrol method and propose Dynamic Token Passing (DTP) as a wireless token p assing LAN access control method that incorporates a token circulation meth od and a data relay scheme based on a reserved logical ring. The results sh ow that compared to existing methods, such as the IEEE 802.11 protocol, the proposed method exhibits better performance in an environment suffering fr om transmission path failures caused by blocking objects. A discussion of t he optimum configuration for the reserved logical rings shows that if A res erved logical rings are prepared and the optimum reserved logical ring is s elected, then a network can continue operation under the condition of A-1 f ailures. (C) 2001 Scripta Technica.