Routing with Cooperative Transmissions in Wireless Ad Hoc Networks

Cooperative transmissions emulating
multi-antenna systems may help reduce the total energy
consumption in wireless networks. In this book, we define a
virtual Multiple-Input Single-Output (vMISO) link to be
established when a group of transmitters jointly enable
space-time communications with a single receiver. We present
a novel approach in characterizing the optimal multi-hop
vMISO routing in ad hoc networks. The key advantages of
vMISO links are the increase in transmission range and the
decrease in the required transmission energy due to
diversity gain. Specifically, we solve a nonlinear program
that minimizes the total energy cost of reliable end-to-end
transmissions by selecting the optimal cooperation set. Our
results indicate that a multi-hop vMISO system is energy
efficient only when a few nodes cooperate at each hop. We
design a new greedy geographical vMISO routing protocol.
Also, we formulate the network lifetime maximization with
vMISO routing as a nonlinear program. Then, we present a
novel cooperation set selection and flow augmentation based
routing heuristic that can significantly increase the
network lifetime compared to Single-Input Single-Output
systems.