A Study of Cell Assignment Problem of the Two-Level wireless ATM Network
|關鍵字:||細胞指派問題;無線非同步傳輸模式網路;基因演算法;模擬退火;啟發式演算法;cell assignment problem;wireless ATM;genetic algorithm;simulated annealing;heuristic algorithm|
Recently, there has been some interest in extending ATM (Asynchronous Transfer Mode) technology to the wireless environment. The motivation behind this extension (termed wireless ATM) includes the desire for seamless interconnection of wireless and ATM networks, and the need to support emerging mobile multimedia services. In this dissertation, we investigate the problem of optimum assignment of cells in PCS (Personal Communication Service) to switches in a wireless ATM network. Given cells and switches in an ATM network (whose locations are fixed and known), the problem is assigning cells to switches such that the cost can be minimized. The cost has two components, one is the cost of handoffs that involve two switches, and the other is the cost of cabling. In this dissertation, first, this problem named cell assignment problem is modeled as a complex integer-programming problem. Since finding an optimal solution to this problem is NP-hard, we develop several heuristic algorithms, genetic algorithms, and a simulated annealing algorithm to solve this problem. Experimental results show that these algorithms have good efficiency. Second, due to the tremendous growth in the usage of mobile phone, the call may be dropped if the congestion occurred at the base station. To provide better quality of the communication, new base stations may be added into the PCS network or cell may be split to increase the whole capacities of the PCS network. Moreover, the original connections between cells and switches may be out of date or the handoff traffic between cells may be changed. After the number of base stations is increased, how to assign newly added and split cells of PCS network to switches in ATM network such that the total cost is minimized is an important issue. Furthermore, extended cell assignment problem and the network expansion problem are formulated and solved. Beside, since the availability and the reliability of the wireless ATM network are important. We also solve the dual-homing cell assignment problem, which allows each cell can be assigned to two switches in ATM network. For the different kinds of cell assignment problem, genetic algorithms are proposed to solve these problems.
|Appears in Collections:||Thesis|