Optimization of polling sequence during fading interval in wireless systems

Within indoor wireless channels, the duration of channel fading can be very long, for which reliable packet exchanges between wireless devices may not be possible. During that period, some packets are continuously transmitted to check if the channel becomes available. However the transmission of channel checking packets reduces bandwidth efficiency. In this paper, we propose an optimization scheme for transmitting the checking packets such that the bandwidth loss caused by them is minimized. For this purpose, two loss factors, which are termed as the common loss and the private loss, are introduced and a new cost function based on these factors is proposed. To find the optimized time sequence of checking packets, we propose a new search method based on the proposed cost function, which achieves very low computational complexity. Moreover, we derive a condition under which the searched solution turns out to be unique. Performance of our algorithm is verified by some numerical simulations for various fading distributions.