Future generation networks will be seen as a new initiative to bring together all heterogeneous wireless and wired systems under the same framework, to provide connectivity anytime and anywhere using any available technology. Network convergence is therefore regarded as the next major challenge in the evolution of telecommunications technologies and the integration of computer and communications. We begin this article with an outline of the design tenets for an interworking architecture between both Long Term Evolution (LTE) and mobile WiMAX technologies. We then define the various functional entities and their interconnections needed for their interworking. Next, we discuss the end-to-end protocol layering in the interworking architecture, network selection and discovery, and IP address allocation. Finally, we describe in more detail the functional architecture and processes associated with security, QoS, and mobility management.