Cross-Layer Design of MANETs: The Only Option

The current Internet protocol (IP) architecture model for mobile ad hoc network (MANET) routing protocol development ignores cross-layer effects by seeking to emulate as closely as possible the wireline architecture. Nevertheless, cross-layer effects are unavoidable and it is actually desirable to exploit these interactions to achieve greater performance. Further, support for cross-layer information flow is necessary for many of the applications envisioned for MANETs. We review the purpose of the IP architecture and argue that the MANET architecture model is not only unsuitable for exploiting cross-layer effects it also violates the very intent of the IP architecture. By focusing the standardization effort on making routing solutions and placing them at the point of integration, just above IP in the protocol stack, it effectively stifles the IP development goals of supporting local subnetwork optimization and long term innovation. We review issues of cross-layer design and then propose an alternative standardization effort that would preserve the opportunity for innovation while ensuring the integration of MANET subnetworks into larger integrated heterogeneous IP networks. Our proposal places MANET into its own subnetworking layer and then divides standardization into four parts: the interface to the MANET subnetwork, a heterogeneous routing protocol, mechanisms for cross-layer information flow, and a combined logical and spatially hierarchical addressing scheme. We identify several more radical MANET design proposals that depart substantially from the current model. All could be integrated into a larger heterogeneous IP network using our protocol approach