Network Planning for IEEE 802.16j Relay Networks

Abstract

In this chapter, a problem formulation for determining the optimal node location for base stations (BSs) and relay stations (RSs) in relay-based802.16networksis developed.A numberof techniques are proposedto solve the resulting integer programming(IP) problem—theseare comparedin terms of the time taken to find a solution and the quality of the solution obtained. Finally, there is some analysis of the impact of the ratio of BS/RS costs on the solutions obtained. Three techniques are studied to solve the IP problem: (1) a standard branch and bound mechanism, (2) an approach in which state space reduction techniques are applied in advance of the branch and bound algorithm, and (3) a clustering approach in which the problem is divided into a number of subproblems which are solved separately, followed by a final overall optimization step. These different approaches were used to solve the problem. The results show that the more basic approachcan be used to solve problemsfor small metropolitanareas; the state space reduction technique reduces the time taken to find a solution by about 50 percent. Finally, the clustering approach can be used to find solutions of approximately equivalent quality in about 30 percent of the time required in the first case. After scalability tests were performed,some rudimentary experimentswere performed in which theratioofBS/RS costwasvaried.Theinitialresultsshowthatforthescenariosstudied,reducingthe