The Optimal Location Update Strategy of Cellular Network Based Traffic Information System

Mobile phone location technology based traffic information system relies on the cellular network data reported by mobile phone to position accurate location. Mobile phone reports cellular network data to mobile switching center when it is necessary to update location at times of mobile phone switched on, active state or update timer expired during idle state. The purpose of location update is to ensure each call can be delivered to exact destination in time and efficiently. The higher update frequency is, the faster each call can be connected and therefore, more sufficient traffic data can be obtained to make traffic information more reliable. However, frequent updates increase network load and decrease service level. Therefore, there is a trade-off between operation cost and traffic information quality in generating the best update strategy. This paper develops analytical models to analyze the optimal location update strategy with the objective of minimum total cost. The optimal analytic results and numerical analysis show that the higher the average travel speed of mobile phones, the lower the update cycle and the higher the update distance threshold. When traffic condition becomes worse, it´s suggested to increase update cycle with the constraint of tolerant update cycle by traffic information system