Multi-level access priority channel allocation strategies in Global System for Mobile communications (GSM) networks

Global System for Mobile communications (GSM) telephony has great impact in cellular communication technology because of its ability to accomodate more subscribers than the analog telephone. As a result, many calls are now on the network to seize the scarce radio resources available in GSM spectrum thereby leading to congestion most of the time. This work focuses on how the congestion experienced on the GSM network can be minimized. The voice call on the network is subclassifled into four classes namely special call (s_v), handoff call (h_v), retrial call (r_v) and new call (n_v). A level of priority was established among the classes so that the most urgent and important service will have access to the channel on the network by preempting the lower priority services when there is congestion and there is no free channel to communicate. The voice communications over the GSM network using the different classes of subscribers were analyzed with Markov chain´s model. The steady state probabilities for voice services were derived using Multidimensional Erlang B. The blocking and dropping probabilities models for the different services were later developed. The impacts of priorities on different subscribers in the network were shown through the graphical display of the results. The work shows that the models used gave significant reduction in congestion when compared to the traditional Erlang-B model normally used to control congestion in GSM.