Improved strategy of time-frequency opportunistic spectral usage for multi-rate wireless systems

In this paper, we present an improved strategy of channel probing and transmission scheduling in a multi-rate wireless system. We consider a fixed data time model, where time is slotted and channel states do not change within one slot. In a multichannel wireless system, a transmitter can opportunistically use channels with high-quality conditions. In order to make better decisions and find out the channel with the maximum transmission rate, the transmitter should probe individual channels by sending control packets, which will consume time and energy, thus reduce effective time for actual data transmission. In fact, the coherence time of the channel may be much larger than the duration of one slot. We can send multiple back-to-back packets if the channel are always in good conditions. Leveraging the absorbing Markov chain model, we propose a strategy for opportunistic spectral usage, in which both time and frequency domain process are taken into account.