Message Scheduling for Efficient Data Communication Under Varying Channel Conditions

This paper deals with the problem of optimizing the decisions as to when to schedule transmissions of messages under varying channel conditions. A cost function is minimized which is a sum of delay cost and resource cost. An exponential delay cost function is utilized which is unconventional, but has some realistic qualities as well as mathematical convenience. Most of the analysis is based on using the two-state Markov model of channel conditions. However, to improve realism, the bad channel state is assumed in some cases to have several modes of different expected durations, but the mode is not known to the user. Results are derived for two cases. One case is that of a single, lightly loaded two-state channel where a message arrives during a bad state. A second case is where there is time sharing of transmission over different channels where conditions on the different channels vary differently.