LMDS/LMCS hub interconnection alternatives and multiple access issues

LMDS/LMCS is a broadband wireless local loop, millimeter-wave alternative to emerging integrated multiservice access networks. Significantly large amounts of bandwidth - in the order of one GHz of spectrum - are made available to residential subscribers or supported business users respectively that employ highly directional antennas and signal polarization to establish communication with a central hub. Besides the requirement for dynamic bandwidth allocation capabilities, these networks should be able to guarantee negotiated quality of service (QoS) levels to a number of constant-length (ATM) - and possibly variable length (TCP/IP) - packet streams. In this context, we analyze the performance of contention, polling/probing and piggybacking mechanisms that will be used by the LMDS MAC protocol for the dynamic support of both real-time and non-real-time traffic streams. More specifically, we focus on the end-to-end performance of a real-time variable bit rate connection for which the LMDS link is only the access component of a multi-link path through an ATM network. Results are presented on maximum end-to-end cell delays under a Weighted Round Robin service discipline and buffer requirements are calculated for no-loss conditions. In parallel, we also consider the case in which variable length IP packet traffic is supported as such by the same wireless access network. Backbone interconnection alternatives of LMDS hubs, multiple access proposals and scheduling algorithms are addressed in this framework. [PUBLICATION ABSTRACT]