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This paper proposes an adaptive routing protocol called ARFA for an integrated cellular and ad hoc heterogeneous network with flexible access (iCAR-FA). Based on the presentation of the iCAR-FA physical characteristics, the paper details the design issues and operation of ARFA. Detailed numerical analysis on route request rejection rate, which is along with some general evaluations, has indicated the effectiveness and efficiency of the ARFA protocol.

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Integrated Cellular Networks (ICNs) are normally constructed by adding ad hoc overlay on cellular networks to solve the latter's flexibility and capacity expansion problems. In such networks, routing plays a critical role in finding a route to divert congested traffic from a congested cell to another less crowded cell. While much work has been conducted on routing protocols in ICNs, no dedicated work has been found for an important aspect of routing, namely source selection. The process of a source selection can be an algorithm which is designed for selecting a proper pseudo source to releases its occupying channel to a blocked mobile user. Consequently, this pseudo source diverts its ongoing call to another cell by using a free channel in a neighbor cell via a relaying route. Based on an introduction of a representative ICN infrastructure, this paper proposes three source selection algorithms. Both numerical analysis and evaluation results are presented, which show the efficiency of the algorithms and their different ability in adapting to different network situations, such as traffic density and cell capacity.

In heterogeneous wireless networks, when a mobile host/handset (MH) with multiple wireless interfaces changes its location or requires a certain network service, the MH will require a switch between different wireless networks (namely vertical handoff). A congestion-aware proactive vertical handoff algorithm is proposed, which uses a data pre-deployment technology to realise soft handoff between cellular interface and ad hoc interface. Here, the vertical handoff algorithm is implemented in an experimental heterogeneous network structure called converged ad hoc and cellular network, which is an ad hoc overlay system considering the balancing of the traffic between adjacent cellular cells. By evaluations, it is shown that the proposed algorithm can realise low handoff delay and low packet losses, and help to ease congestion issue existing in the heterogeneous networks.

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