The Optimization of Location Management

Abstract

Binding and tracking are the two major phases of Location Management System (LMS). Thus, the communication costs during these two phases should be considered mostly for LMS optimization, without impairing the LMS performance. This paper describes a new optimization algorithm and, the key points of our improvement are: first, for each mobile terminal, we define more than one “anchor” node between its HLR and the serving VLR and construct a logical chain among all of them; second, the mobile terminal would memorize the current chain structure. Whenever the mobile terminal moves into a region served by a new VLR, the terminal will submit the chain structure which is saved in its memory to the new VLR. Then, the optimizing algorithm is conducted at the new VLR. The Records (that come from the terminal) and the routing information (of the new VLR) are used in the optimizing algorithm. The result of the optimization is a new chain structure in which the new VLR is one end of the chain, (the other end is always HLR of the terminal). After that, the new VLR updates the anchor chain according to the optimization result, and also downloads the new chain structure (the optimization result) to update the terminal’s memory. The binding cost and the tracking cost are both considered in the optimization algorithm. The complexity analysis shows that in the worst case, the total cost (binding plus tracking) with zero call blocking probability can be O(M), which is better than the latest result O(M·log(M)). Here, M is the distance that the terminal has moved. The simulation investigates the efficiency of our improvement with different CMR (Call-toMobility Ratio). Keywords-wireless network, cellular system, mobile computing, mobility management, location management, anchor chain.