The Analysis And Optimization Of GSM Network Call-Drop Rate

With the progressing of telecom reformation, the competition in the mobile communication market has been more and more fierce. In the last 10 years (1999-2008), China Mobile has set up the largest GSM network in the world, now in the highest flight in domestic market compared to other competitions. Since the network covering has reached such a high level, the next step is to enhance network optimization, improve network quality and increase the satisfaction of customer.With the expanding of the network scale and the fast growing of the customer amount, call-drop rate, call-completion rate and congestion rate have become the three major bottlenecks that restrict the improvement of the wireless network quality. Among them, the drop call has especially severe impacts on our customer and call-drop rate has always been one of the important KPI indexes in the test of mobile network quality. To reduce the call-drop rate, achieve and surpass the call-drop rate index target in the mobile network test, Jincheng (China) Mobile carried out the activity of optimizing call-drop rate and reached the target of controlling the call-drop rate. The call-drop rate decreased to about 0.3% and the network quality is enhanced dramatically, which powerfully supported the business expanding.This paper is based on the background of the activity of optimizing GSM call-drop rate in Jincheng Mobile. First, from the theoretical aspect, the definition and classification of the drop call in the mobile telecommunication were introduced. The signal flow of normal call and all kinds of drop call were compared and analyzed. Then the usual reasons of drop call and the corresponding solutions were analyzed from all aspects of the hardware problem, software problem, parameter setup, covering, switch, jamming and transmission of the base stations. Research was done based on the network condition, network structure, the structure and capability of the base station equipment, radio frequency transmission feature and the methods of optimizing network in Jincheng Mobile. Finally, the activity of optimizing GSM call-drop rate was carried out in three steps including network analysis, optimization implement and production consolidation. The call-drop rate is reduced from previous 2.0% to 0.3%. With this activity, the network service quality and economic benefit were enhanced in Jincheng Mobile.