A Preemptive Channel Allocation Mechanism for GSM/GPRS Cellular Networks

• Main Authors: Wei-Chun Yang, 楊薇純
• Other Authors: Tsang-Ling Sheu
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/80341488177947642829

碩士 === 國立中山大學 === 電機工程學系研究所 === 89 === In the near future, the integration of GSM and GPRS services will bring the wireless personal communication networks into a new era. With the extreme growth in the number of users for contending limited resources, an efficient channel allocation scheme for GSM/GPRS users become very important. Currently, existing channel allocation schemes do not consider the various characteristics of traffic classes. Consequently, users can not obtain their optimal channel resources in delivering different types of traffic. In this thesis, a preemptive channel allocation mechanism is introduced for GSM/GPRS cellular networks. Based on the call requests, for different types of services, we classify the traffic into GSM, real-time GPRS and non-real-time GPRS. Two channel thresholds are defined. TGSM/GPRS is used to separate the channels between GSM and GPRS users, while TGPRS_rt is used to separate the channels between real-time and non-real-time GPRS users. Since the two thresholds can be dynamically adjusted based on the number of call requests, the channel utilization is increased and less resources are wasted. Note that in our proposed scheme, high-priority users（i.e., GSM handoff calls）can preempt the channels being used by low-priority users（i.e., non-real-time GPRS calls）. Hence, the call blocking probability of high-priority calls can be significantly reduced and their quality of services can be guaranteed as well. We build a 3-D Markov Chain mathematical model to analyze our proposed channel allocation schemes. The parameters of our interests include the call blocking probability, the average number of active calls, the average call completion rate and the overall channel utilization. To verify our mathematical results, we employ OPNET simulator to simulate the proposed schemes. Through the mathematical and simulation results, we have observed that with the preemptive channel allocation, the high-priority calls（i.e., GSM and real-time GPRS）can achieve relatively low blocking probability while slightly increasing the blocking probability of non-real-time GPRS calls. Besides, the overall channel utilization is greatly improved due to the appropriate channel allocation.