Force-based load balancing in co-located UMTS/GSM networks

Currently UMTS networks are rolled out to compliment existing GSM networks. As most UMTS mobiles will also support GSM, the question of which system to select for a given service emerges. In order to exploit the differences between radio access technologies, common radio resource management (CRRM) is employed, i.e. common management of the whole radio resources such that the assignment of mobiles to different radio technologies is flexible and considers the specific advantages of each system. The focus of the paper is on intelligent algorithms to decide the balancing of the load between the different radio technologies. We study algorithms for optimum assignment of mobiles to a radio technology during call setup as well as during the call. The decision is based on an intelligent evaluation of various aspects of the radio link. Our algorithm is based on an approach previously employed to balance the load of distributed computing systems.

1 Introduction

Currently, UMTS networks are rolled out to complement existing GSM networks. As most UMTS mobiles will also support GSM, the question of which system to select for a given service emerges. A simple solution would be to use UMTS where available and GSM only as a fall back system for areas where UMTS is not available yet. However, as radio resources and infrastructure are costly, the need for more intelligent mechanisms to balance the load between the two systems arises.