A Combined Scheme for Controlling GSM Network Calls Congestion

Abstract

Network congestion and signal quality degradation are the major problems of the Global System for Mobile communication (GSM) most especially as the number of customers increases. They are issues that constantly and continuously demand for further researches to improve network performance. Congestion in various systems has always been tackled with various attempts, all of which falls in either the congestion avoidance category or congestion management category. Congestion avoidance has however been adjudged the best scheme for controlling network congestion and this is the approach employed in this research work. The conventional GSM network calls congestion control methods such as Token Bank, Auto atic Call Gapping among which Call Admission Control (CAC) is the best, was selected for this work. Dynamic load balancing technique was combined with CAC to re-route calls that would have been dropped to another less busy cell within the Base Station Controller (BSC) area. A naive form of Dijkstra shortest path algorithm was used to find the shortest route to which calls can be transferred among the collocated base station cells. The combined algorithms were implemented on JAVA platform using real life call data record (CDR) collected from Globacom Nigeria Limited New Call Blocking and Handoff Call Dropping Probabilities (NCBP and HCDP) were used to measure the performance results. The two probabilities were computed for both CAC only and the combined scheme. The results obtained showed that there is significant reduction in the values of both NCBP and HCDP by 71.43% and 100% respectively, of cells considered for the new combined scheme when compared with that of the CAC only. This indicates that the new scheme has further reduced the values of the NCBP and HCDP which enabled the cells to accommodate more calls thereby increasing the efficiency of the network performance.