QVBR-MAC: A QoS-Oriented MAC Protocol for Variable-Bit-Rate MC-CDMA Wireless LANs

Multicarrier Code Division Multiple Access (MC-CDMA) techniques were originally proposed at mid of 90’s for wideband multi-user communications in wireless environments characterised by hostile propagation characteristics. Problems still to be solved are related to the provision of efficient resource channel allocation in variable-bit-rate transmission. In this work, the design of a MC-CDMA-based WLAN infrastructure is considered. The great advantage of MC-CDMA, i.e. the capability of supporting asynchronous multi-user variable-bit-rate (VBR) transmission over multipath channel with conventional detection, is exploited, jointly with an efficient and real-time Medium Access Control (MAC) strategy, in order to allow a significant number of VBR users to share the same bandwidth with different QoS profiles. Different classes of users will be labeled by the MAC level that has to plan a controlled access to the channel on the basis of the users’ requests and to check the possibility of assuring to them a certain Qos degree. The paper presents an overview of the system and tests its performance through extensive simulation.