  This paper presents the design, implementation and performance evaluation of
a location MAC protocol, called L-MAC, for wireless sensor networks. L-MAC is a
combination of TDMA and CSMA while offsetting the high overhead of time slot
assignment by allocating the time slots to sensor nodes based on their location
information. This design avoids high computation complexity of time slot
assignment incurred by node mobility and node failure. The area which the
wireless sensor network occupies is divided into blocks and each block is
associated with an inter-block time slot and an intra-block time slot. In the
inter-block time slot, the sensor nodes stay active and receive the packets
from nodes outside of the block. In the intra-block time slot, the sensor nodes
communicate with peer nodes in the same block under CSMA. Sensor nodes stay
sleep in all other time slots unless they have traffic to send. L-MAC is
implemented and evaluated in NS-2.
