Globally optimal user-network association in an 802.11 WLAN & 3G UMTS hybrid cell

Abstract

We study globally optimal user-network association in an integrated WLAN and UMTS hybrid cell. The association problem is formulated as a generic MDP (Markov Decision Process) connection routing decision problem. In the formulation, mobile arrivals are assumed to follow Poisson process and a uniformization technique is applied in order to transform the otherwise state-dependent mobile departures into an i.i.d. process. We solve the MDP problem using a particular network model for WLAN and UMTS networks and with rewards comprising financial gain and throughput components. The corresponding Dynamic Programming equation is solved using Value Iteration and a stationary optimal policy with neither convex nor concave type switching curve structure is obtained. Threshold type and symmetric switching curves are observed for the analogous homogenous network cases. © Springer-Verlag Berlin Heidelberg 2007.