Design and performance evaluation of RAC/EAC for wireless ATM environment

To provide a seamless interface to ATM networks and to support the emerging mobile multimedia services, it is desirable to introduce ATM technology in wireless networks also. However this introduction, termed "wireless ATM", presents several interesting challenges. Some of these challenges include managing an end-to-end ATM connection, handling the high error rate performance of the wireless link, maintaining the ATM cell sequence, and supporting the quality of service (QoS) requirement, if any, in the wireless ATM environment. In an ATM network VPIs/VCIs (virtual path identifiers/virtual circuit identifiers) are allocated to virtual paths consisting of switches and links between two stationary users. However, due to the mobility, the access point for a mobile user is not fixed. Therefore, a technique/scheme is required to maintain an end-to-end ATM connection in the wireless ATM environment. The design of such techniques has received some consideration in the literature. These schemes, such as the use of multiple circuit numbers per mobile user and the assignment of VPI/VCI to base stations, introduce a processing complexity in the wireless network. However, the ATM networks are likely to be operating at a higher speed than the wireless networks and, therefore, are less likely to become a bottleneck when a high rate of handoffs is encountered. This paper presents the design and performance evaluation of a dynamic scheme for connection management in a wireless ATM environment. The scheme, termed rearrange ATM connection/extend ATM connection (RAC/EAC), places the handoff processing in ATM network first, and if the NCP (network call processor) is unable to process the request in time, then it is performed in the wireless network.