Scheduling in Multi-Channel Wireless Networks

The availability of multiple orthogonal channels in a wireless network can lead to substantial performance improvement by alleviating contention and interference. However, this also gives rise to non-trivial channel coordination issues. The situation is exacerbated by variability in the achievable datarates across channels and links. Thus, scheduling in such networks may require substantial information-exchange and lead to non-negligible overhead. This provides a strong motivation for the study of scheduling algorithms that can operate with limited information while still providing acceptable worst-case performance guarantees. In this paper, we make an effort in this direction by examining the scheduling implications of multiple channels and heterogeneity in channel-rates. We establish lower bounds on the performance of a class of maximal schedulers. We first demonstrate that when the underlying scheduling mechanism is "imperfect", the presence of multiple orthogonal channels can help alleviate the detrimental impact of the imperfect scheduler, and yield a significantly better efficiency-ratio in a wide range of network topologies. We then establish performance bounds for a scheduler that can achieve a good efficiency-ratio in the presence of channels with heterogeneous rates without requiring explicit exchange of queue-information. Our results indicate that it may be possible to achieve a desirable trade-off between performance and information.