DDR: A distributed dynamic reservation scheme that supports mobility in wireless multimedia communications

We present a distributed dynamic reservation (DDR) scheme that supports mob ility in wireless multimedia communications, noting that low handover block ing and high channel utilization are possible if channel reservation can be done dynamically. As the traditional reservation schemes do not fit to han dling time-varying multiclass multimedia traffic due to the involved comput ational complexity, we employ an elaborate two-regional approximation schem e that can reduce the computation dramatically. We approximate the channel occupancy distribution based on the observation of arrival rates, means, an d variances of total calls and handover calls, which can be easily measured locally at each base station or switch in a distributed manner. The approx imation is made by arranging the distribution into two regions such that a simple distribution model can be applied in each region and then joining th e two regions using legitimate boundary conditions. This approximation enab les us to estimate the relevant number of reservation channels very quickly , with the computational complexity reduced to the order of O (log C) for t he channel capacity C. Nevertheless, the estimation turns out very close to the exact solution determined by applying the multidimensional Markov chai n approach. Simulation results reveal that the proposed DDR scheme can adap t itself well to time-varying multiclass multimedia traffic and achieve hig h channel utilization, yet maintain a very low handover blocking probabilit y.