  The existing distributed TDMA-scheduling techniques can be classified as
either static or dynamic. The primary purpose of static TDMA-scheduling
algorithms is to improve the channel utilization by generating a schedule of
shorter length. But, they usually take a longer time to schedule, and hence,
are not suitable for WSNs, in which the network topology changes dynamically.
On the other hand, dynamic TDMA-scheduling algorithms generate a schedule
quickly, but they are not efficient in terms of generated schedule length. In
this paper, we propose a new approach to TDMA scheduling for WSNs, that bridges
the gap between the above two extreme types of TDMA-scheduling techniques, by
providing the flexibility to trade-off between the schedule length and the time
required to generate the schedule (scheduling time). The proposed TDMA
scheduling works in two phases. In the first phase, we generate a TDMA schedule
quickly, which need not have to be very efficient in terms of schedule length.
In the second phase, we iteratively reduce the schedule length in a manner,
such that the process of schedule length reduction can be terminated after the
execution of an arbitrary number of iterations, and still be left with a valid
schedule. This step provides the capability to trade-off between schedule
length and scheduling time. We have used Castalia network simulator to evaluate
the performance of proposed TDMA-scheduling scheme. The simulation result
together with theoretical analysis shows that in addition to the advantage of
trading-off the schedule length with scheduling time, the proposed TDMA
scheduling approach achieves better performance than existing algorithms in
terms of schedule length and scheduling time.
