  We study the minimum latency broadcast scheduling (MLBS) problem in
Single-Radio Multi-Channel (SR-MC) wireless ad-hoc networks (WANETs), which are
modeled by Unit Disk Graphs. Nodes with this capability have their fixed
reception channels, but can switch their transmission channels to communicate
with their neighbors. The single-radio and multi-channel model prevents
existing algorithms for single-channel networks achieving good performance.
First, the common assumption that one transmission reaches all the neighboring
nodes does not hold naturally. Second, the multi-channel dimension provides new
opportunities to schedule the broadcast transmissions in parallel. We show MLBS
problem in SR-MC WANETs is NP-hard, and present a benchmark algorithm: Basic
Transmission Scheduling (BTS), which has approximation ratio of 4k + 12. Here k
is the number of orthogonal channels in SR-MC WANETs. Then we propose an
Enhanced Transmission Scheduling (ETS) algorithm, improving the approximation
ratio to k + 23. Simulation results show that ETS achieves better performance
over BTS, and the performance of ETS approaches the lower bound.
