  Efficient radio spectrum utilization and low energy consumption in mobile
devices are essential in developing next generation wireless networks. This
paper presents a new medium access control (MAC) mechanism to enhance spectrum
efficiency and reduce energy consumption in a wireless ad hoc network. A set of
coordinator nodes, distributed in the network area, periodically schedule
contention-free time slots for all data transmissions/receptions in the
network, based on transmission requests from source nodes. Adjacent
coordinators exchange scheduling information to effectively increase spatial
spectrum reuse and avoid transmission collisions. Moreover, the proposed MAC
scheme allows a node to put its radio interface into a sleep mode when it is
not transmitting/receiving a packet, in order to reduce energy consumption.
Simulation results demonstrate that the proposed scheme achieves substantially
higher throughput and has significantly lower energy consumption in comparison
with existing schemes.
