This work presents two different propositions which mark new advances in WiMAX. The first work addresses multiservice environment and service differentiation in WiMAX networks. It argues that, using only polling based priority scheduling at subscriber stations and demand based dynamic bandwidth allocation (DBA) at the base station, it is possible to serve various traffic types in WiMAX systems with only three service classes rather than four as proposed in the standard. It reduces the complexity of scheduling mechanisms to be implemented in WiMAX interface cards thus bringing down overall capital expenditure (CAPEX) model for such system while providing QoS to applications. Both the transfer plane QoS, in terms of latency and jitter, and the command plane QoS, in terms of blocking probability are assessed. In particular, a simple, multiservice call admission control (CAC) mechanism is proposed that significantly improves on a previously proposed CAC mechanism by favouring real time traffic over non real time traffic. The second work proposes an architecture for a hybrid system composed of WiMAX (access network) and WiFi systems. A new “tightly coupled” approach considers matching parameters at MAC level which translates directly into the transfer of requirements from WiFi network to WiMAX. A notion of jitter in WiFi systems is also introduced.