Abstract—Next generation wireless networks will take advantageof the popularity and the data rates offered byunlicensed wireless networks to enhance cellular services.Nowadays, it is not surprising to see heterogeneous wirelessnetworks coexisting on a daily basis i.e. UMTS, WiFi,and WiMAX. Unfortunately, technical issues and the lackof roaming agreements between network operators preventinteroperability. One of the goals of next generationwireless networks is to enable service mobility betweenheterogeneous wireless networks, thus we present in thisarticle a SIP-based roaming architecture to enable servicemobility in heterogeneous multi-operator wireless networks.Our objective is to establish mutual trust between cellularnetwork operators and unlicensed wireless networks througha efficient SLA monitoring and enforcement and brokerbasedaccess control. All this, with minimal changes incurrent wireless network architectures.

Index Terms—wireless convergence, service mobility, roamingarchitecture, heterogeneous wireless networks.

Cite: Oscar Salazar Gait´an, Philippe Martins, Jacques Demerjian, and Samir Tohm´e, "Enabling Roaming in Heterogeneous Multi-Operator Wireless Networks," Journal of Communications, vol. 2, no. 4, pp. 18-28, 2007.