Reservation Based MAC Protocol for a Wireless ATM LAN
A major issue in the WATM system design is the selection of a suitable channel sharing/media access control (MAC) technique at the data link layer. This thesis attempted to design a wireless “multimedia capable” MAC approach that provides a sufficient degree of transparency for many ATM applications. An attempt has been made during the course of this work to come up with a reservation based MAC protocol which satisfies the service requirements of different traffic classes. The basic idea behind the reservation-based MAC protocol is a sequence of Control-Data Frames (CDFs); each of which consists of a control phase followed by a data phase. During the control phase, wireless terminals who wish to transmit in the next CDF send a message to the base station (central controller) along with the detailed signaling information about the packets queued at the buffers, using a very efficient signaling scheme called the “superslot scheme”. The base station then allots (reserves) the slots among different users using the proposed Slot Allocation Policy. The slot allocation takes into account both the bandwidth guarantees made to each service at the time of connection set-up and also the dynamic state information obtained from the mobiles every CDF. This ensures that QoS guarantees can be met in a bandwidth efficient manner. Results obtained from a discrete event simulation of the system using a network simulator called BONeS show satisfactory performance of the protocol.