| dynamic Time Division Multiple Access (TDMA) polling-base scheme is proposed for an indoor broadband wireless LAN. The protocol attempts to bridge the existing and rapidly-growing ATM technology to that of personal communications systems and should be capable of handling variable bit rate as well as constant bit rate connections. The system assumes a microcellular architecture with a low frequency reuse such as 3 or 4. To combat the severe co-channel interference, which is expected to be the dominant transmission impairment, switched sector-beam antennas are used on both portables and base stations.;The fixed-length frame gated-limited polling multiple access consists of a number of subframes corresponding to each of the sectors of the antenna. Portables are polled and serviced with a rate that is determined by their average bit rate and service requirements. The subframes may be randomized in order to randomize the interference and allow the error control procedures to bring the performance of the system to the required level. Selective ARQ is proposed to enhance the reliability of the transport link.;An analytical study is carried out for a simplified scenario where a terminal is polled and serviced by a central server. The study takes into account the ARQ retransmissions and the TCMA frame structure. Results such as the probability generating function of buffer size and bounds for the traffic delay are obtained. The effect of temporal dependences in the traffic stream (nonrenewal models) or lack of it (renewal models) is also studied.;The steady state performance of the system in terms of cell loss probability, call block and drop probabilities, traffic cell waiting time, and portable buffer occupancy are evaluated by simulation. A 4... |
