New calls blocking analysis in cellular systems based on Markov chain model

The enormous growth of wireless networks has made efficient use of the radio spectrum which is divided into a set of disjoint channels. These channels can be used simultaneously by using an optimal channel allocation scheme. The main limitation with such wireless systems is the number of available channels. Frequency reuse and channel assignment techniques are used to increase the system capacity. In order to avoid interference with other channels, each channel is given a frequency, a time slot, a spreading code or a combination of any of these. Two non-borrowing FCA (fixed channel assignment) schemes, non-prioritized scheme (NPS) and reserved channel scheme (RCS), are compared. In NPS, all the channels in a cell are available for both initial and handoff calls; in RCS, some channels are reserved for handoff calls and the remaining channels can be utilized for both initial and handoff calls. The formulae for computing blocking probabilities for initial and handoff calls are derived using steady state balance equations defined by a Markov chain model. From simulation results, graphs are plotted of blocking probabilities versus total number of channels. These show that the blocking probability is a decreasing function of the number of channels.