Multi-Level Tabu Search for 3G Network Dimensioning

We investigate the dimensioning of 3G wireless networks with a CDMA2000 radio interface technology. These networks offer a range of multimedia services that require different end-to-end QoS. In order to meet this QoS, dimensioning of a 3G network must include an handshake between the radio and the core networks and therefore involve the three networks (radio, core, access). In this paper we primarily address the problem of optimizing the base station locations and the core network link capacity with different multimedia traffic scenarios and different QoS and GoS requirements. The dimensioning problem is formulated as a mixed integer program (MIP) problem and solved by a tabu search (TS) algorithm that relies on the signal to noise plus interference ratio (SNIR) to guide its search strategy. In order to improve the efficiency of the tabu search, we study extensively various of its key features: (i) search intensification through dynamic tabu lists and aspiration criteria; (ii) search diversification through restarts using new base station locations. We next conduct experiments with the resulting tabu search (TS) on quite large instances. The MIP formulation can be used to evaluate the quality of those solutions. It is then showed that the TS solutions are almost optimal on small instances and requires much less resources than the approximated solutions obtained with the MIP formulations, even for larger instances.