Centralised multi-class Access Control in a WiMAX-UMTS hybrid network

With the ever-increasing proliferation of air interfaces that coexist in the same operating area, advanced Radio Resource Management is crucial to take advantage of the available system resources. In this paper, we consider a downlink multi-class heterogeneous network where cells include two co-localized Radio Access Technologies (RAT): WiMAX [1] and UMTS [2]. We propose a Centralised Access Control algorithm responsible of assigning every arriving user to one of the two RATs, while taking into account the joint spatial distribution of already accepted users, the current load of each RAT, the location of the newly accepted user and its influence on global performance. The routing decision is formulated as a Semi Markov Decision Process (SMDP). We show how to obtain an optimal policy that maximizes a predefined reward function accounting for both the operator and users satisfaction.