A hybrid approach for RAT selection in wireless heterogeneous networks

Given the diversity and heterogeneity of the existing wireless radio access technologies, a key problem that arises in this context is the radio access network selection. The purpose of radio access network selection is to improve the quality of service experienced by clients and optimize the use of available radio resources. In this context, two approaches can be adopted: either a centralized or a distributed approach. In this paper, based on the two existing radio network selection approaches, we propose a new hybrid approach that combines the distributed one with periodic centralized interventions. We introduce the concept of the proposed hybrid approach, and study its performance. In the hybrid approach, client inbound sessions perform a distributed network selection while the system regularly intervenes to change client associations and/or to modulate the distributed algorithm in order to guarantee an acceptable level of performance. The results show that the hybrid approach performance is close to that of the optimal solution, and is better than that of the distributed approach in specific scenarios. Moreover, the hybrid approach reduces the overall signaling load for the system by decreasing the number of required handovers.