  Heterogeneous wireless networks with wireless devices supporting multitude of
radio access technologies are witnessing increasing interest from network
providers and consumers alike. Energy efficiency in such networks has become an
important design consideration due to the limited battery life of mobile
terminals on one side, and the ever increasing operational expenses pertaining
to energy expenditure on the other. In this paper, we present a routing
protocol for multi-radio multi-hop wireless networks, which aims to achieve a
trade-off between energy consumption in the network and routing delay,
considering both the energy consumption at the devices and the link energy
costs. We also present optimum route-path selection strategies by defining a
utility function to minimize the energy consumption in the network while
maximizing the network lifetime. Using simulations, we verify the utility of
the route-path selection strategies and the efficiency of the energy aware
routing algorithm. It turns out that the proposed protocol is energy efficient
in terms of path selection, with a slight compromise in the end-to-end delay.
