Research On Channel Assignment Algorithms In Mobile Communication System

As the most widely used communication system today, the conflict between the enormous users and the limited frequency resource of GSM system is escalating. Being the key part of Radio Resource Management algorithms, channel assignment strategy is always a hot subject of research with its high improvement of spectral efficiency and quality of speech, efficient reduction of the interference between users, and therefore addition to network capacity.Firstly, analyzing the channel assignment algorithms of cellular mobile systems, a new dynamic channel assignment method which can be used in frequency tightly reuse network is proposed. With a better evaluation of the channels based on the interference measurement, the new method can optimize the utilization of radio resource through dynamic channel selection, and therefore solve the inadaptable problem of the traditional one in tightly reuse network. Through the fixed interference relationship of the users in cyclic hopping synchronized networks, each channel candidate is evaluated with the prediction of the achievable carrier-to-interference ratio(CIR), therefore made the distribution of interference optimized according to the difference demands of users, and finally channel of better CIR and less interference to the others is allocated.Secondly, a simulation platform of GSM cellular system with OPNET is designed by the team, and the part of the realization of dynamic channel allocation methods is my contribution. Through the system-level simulation of the proposed dynamic channel assignment method and the traditional one, the access performance, persistence performance, network quality and capacity of them are analyzed and compared in detail. Through the results of the congestion rate, drop rate, bad period rate, etc., a conclusion can be made that the proposed one is of better performance.Finally, the corresponding power control algorithms with the new channel allocation method are also researched. Through the system-level simulation, each scheme is simulated and compared, and a matching power control algorithm is found ultimately.