24 - Wireless Asynchronous Transfer Mode (ATM) in Data Networks for Mobile Systems

Abstract

This chapter discusses the migration path from the existing fixed asynchronous transfer mode (ATM) LAN standards to ATM wireless LAN (ATM WLAN), describing the functions related to radio link access, the implications on transport protocols, and the support of user mobility. ATM WLAN is envisioned as a system of densely populated wireless-access parts with small coverage areas and an ATM-oriented backbone network that could span a geographical area, justifying the term LAN. Some of the solutions presented could be adopted in wide area networks too. To establish the migration path, one must take into account the characteristics and requirements of the services supported in ATM networks. The same service characteristics must be supported in the ATM WLAN. ATM networks are characterized by point-to-point links leading to star-based topologies, at least for the access part of the network. This issue affects the selection of the multiple access schemes for ATM WLAN and favors centralized adaptive schemes. It is still important to investigate the interaction between the proposed multiple access scheme and the transport layer supporting user applications. Thus, the performance of transport control protocol (TCP) over the adopted multiple access control (MAC) scheme for the ATM WLAN is also investigated. The chapter concludes that by adopting an ATM cell retransmission policy, the throughput of the TCP layer can approach the maximum value.