Mobile nodes in a mobile ad hoc network communicate with each other. In order to facilitate communication of mobile nodes with fixed nodes in the Internet, gateways are used. The resultant integrated heterogeneous architecture is called Integrated Internet MANET in the literature. Such heterogeneous architectures are needed in order to realize the potential of, and to achieve the stated objectives of proposed 5G networks of the future. Gateways in Integrated Internet-MANET may be fixed or mobile. Several issues arise in Integrated Internet-MANET. In this paper, three critical issues encountered in Integrated Internet-MANET are addressed together. These issues are, efficient gateway selection mechanism, adjusting the gateway advertisement range and dynamically adapting the periodicity of gateway advertisements. Three strategies are proposed which use a path load balancing mechanism for efficient gateway selection. These strategies address the issues of adjusting the gateway advertisement range and dynamically adapting the periodicity of gateway advertisements in different ways. The proposed strategies have been simulated in a two-tier as well as a hybrid architecture using network simulation tool ns-2. The simulation results are presented and the scenarios, under which each of the proposed strategies is useful, are discussed.

The communication range of devices within a mobile ad hoc network is inherently restricted. One way of enhancing the communication range of a mobile ad hoc network, is to interconnect it to a wired network like the internet, thus forming a heterogeneous wired cum wireless network. This interconnection also enables mobile nodes to access internet services, and is achieved through gateways. Mobile nodes in the ad hoc network need to discover and register with a gateway in order to obtain Internet connectivity. Gateway discovery mechanisms called proactive, reactive and hybrid exist to enable mobile nodes to register with internet gateways. In the recent times, few optimizations have been proposed to the existing gateway discovery mechanisms in order to make gateway discovery by mobile nodes efficient. In this paper, we present a detailed survey of the state of the art in gateway discovery and selection mechanisms.