Efficient Time-Based Topology-Dependent Scheduling for Radio Packet Networks
Abstract
In Radio Packet Network (RPN), unconstrained transmission may lead to
collision of two or more packets. Time Division Multiple Access (TDMA)
protocol is a common used protocol to schedule collision-free
transmission for such networks. TDMA transmission allows a number
of users to access a single radio channel without interference by
allocating unique time slots to each user. In TDMA network, time
is divided into frames and a frame consists of time slots. For
networks where each node is a neighbor for all the other nodes,
each node should assign a different time slot in TDMA frame to
transmit in it to have collision-free transmission. Typically,
those time slots are ended by \emph{guard times} for propagation
delays. Those guard times are fixed for all time slots regardless
the actual needed propagation delays.
In this paper, we propose a topology-dependent algorithm that
automatically schedules collision-free channel access and specify
the time instant when a node is to send a packet. We use
variable guard times, instead of the fixed ones, calculated using the actual needed propagation delays between sources and
destinations. We show that with such scheduling algorithm, a 90%
saving in the original guard times could be achieved that
increases the network utilization by about 10%.
Also UMIACS-TR-2002-57