Research Of Admission Control In Cellular Mobile Networks With Retrial Phenomenon

Call Admission Control (CAC) is a very important part of the wireless resource management in cellular mobile networks. It is an important issue in wireless network research that how to serve more customers using scarce wireless resource, improve the using utility of wireless resource and at the same time guarantee the users' Quality of Service (QoS). Retrial phenomenon, which has a significant negative impact on the network performance, is non-neglectable in the CAC. Although researchers have done much work on the CAC in cellular mobile networks with retrial phenomenon, they do not differentiate the retrial calls and new calls on admission.Based on the background mentioned above, the research, "Research of Admission Control in Cellular Mobile Networks with Retrial Phenomenon", is proposed. The impacts that the retrial calls make on the cellular mobile networks and the users' QoS are studied. Feasible retrial priority admission algorithms and an adaptive algorithm are proposed. A lot of and strict simulations are done in this paper, and the simulation results indicate that the proposed algorithms improve the users' QoS and system performance. The algorithm performances under various conditions are studied too. The research in this paper provides some valuable references for the wireless network design and management.The issues of CAC with guard channels and CAC with retrial phenomenon are studied in this paper. Based on the queuing theory, Four-priority Retrial Priority Admission (FRPA) algorithm and Three-priority Retrial Priority Admission (TRPA) algorithm are proposed. The basic philosophy of the algorithms is that giving the retrial calls higher priority on admission will decrease the blocking rate of retrial calls and then alleviate the retrial calls' negative impact on the network performance. According to the fact that the network load is time varying, we also propose a Threshold Channel Adaptive Algorithm (TCAA) based on TRPA. In order to evaluate the performance of the algorithms, we propose the following parameters: total first retrial call blocking rate (Pfrb), total second retrial call blocking rate (Psrb), total cell blocking rate (Pab), new call retrial blocking rate (Pnrb), handoff retrial blocking rate (Phrb) and non-handoff blocking rate (Pnhb).The feasibility of the priority algorithms and the adaptive algorithm are studied through the analysis of the signal structure of the random access procedure in the GSM network. The thoughtway can be implemented into other cellular networks (such as CDMA system).Many simulation experiments are done in this paper. The simulation results indicate that the retrial phenomenon has significant negative impact on the network performance, and the FRPA algorithm efficiently decreases the Pfrb and Psrb and then improves the cell performance with retrial phenomenon. The simulation results also indicate that the TRPA algorithm efficiently decreases the Pnrb and Phrb and then decreases the Pab and improves the global system efficiency. The optimal system load range for the priority algorithm is also discussed by simulation. Through the simulation, we also manifest that the TCAA can adjust the threshold channels according to the variety of the system load (the handoff call arriving intensity) and keep the handoff dropping rate under the threshold, and then improves the using utility of the channels and the global system performance. We also study the performance of the TRPA algorithm under various retrial interval distributions (such as Negative Exponential, Erlang, Uniform, Constant, Lognormal, Rayleigh, Standard Weibull) and various intervals, and make out some valuable conclutions.