In this paper, we study joint radio resource man- agement (JRRM) in heterogeneous networks and we propose a way of achieving optimality. We consider a micro, pico or femto cell with two co-localized radio access technologies (RAT), e.g. WLAN and HSDPA. RAT are mainly characterized by the data rates they offer at a given distance of the access point (resp. base station). Dual-technology mobile stations (MS) are initiating downlink packet calls in the considered cell. A network controlled joint RRM algorithm is responsible to assign MS to a RAT, while taking into account the joint spatial distribution of already accepted MS, the current load of each RAT, the location of the newly accepted packet call and its influence on the global performance. Two classes of JRRM algorithms are considered. In a study based on the Semi Markov Decision Process (SMDP) theory, we show how to obtain optimal policies for each of these classes. Optimality is here defined through a utility function accounting for user satisfaction and blocking.