Betting on Gilbert-Elliot channels

Abstract

In this paper a communication system operating over a Gilbert-Elliot channel is studied. The goal of the transmitter is to maximize the number of successfully transmitted bits. This is achieved by choosing among three possible actions: (i) betting aggressively by using a weak code that allows the transmission of a high number of bits but provides no protection against a bad channel, ii) betting conservatively by using a strong code that perfectly protects the transmitted bits against a bad channel but does not allow a high number of data bits, iii) betting opportunistically by sensing the channel for a fixed duration and then deciding which code to use. The problem is formulated and solved using the theory of Markov decision processes (MDPs). It is shown that the optimal strategy has a simple threshold structure. Closed form expressions and simplified procedures for the computation of the threshold policies in terms of the system parameters are provided. If a feedback channel is available, it is shown that the total number of transmitted bits increases.

To Transmit Now or Not to Transmit Now

“…In a different context, existing work applied tools from Markov decision processes to solve communication problems over time-varying links, e.g., [37], [38], [53]. In their work, Laourine and Tong considered actions with a variable number of bits being sent in each action [38].…”

“…As in [38], [42]- [44], we assume that the current state of the link is not known to the sending process. The sender can however benefit from the feedback regarding previous transmissions to guess the current state.…”

Communication over a time correlated channel with an energy harvesting transmitter

“…In [17], the authors investigate the problem of optimal access to a GilbertElliot channel, wherein an energy-unlimited transmitter senses the channel at every time slot. In [18] channel sensing is done only occasionally. The transmitter can decide to transmit at a high or a low rate without sensing the channel; or can first sense the channel and transmit at a reduced rate due to the time spent for sensing.…”

“…The transmitter can decide to transmit at a high or a low rate without sensing the channel; or can first sense the channel and transmit at a reduced rate due to the time spent for sensing. The energy cost of sensing is ignored in [18].…”

Sensing and Communication Tradeoff for Cognitive Access of Continues-Time Markov Channels

“…The tradeoff between sensing and rate has been studied in [15], [16], [17] for the single channel scenario. In [15], optimal tradeoff between throughput and sensing cost is solved using an MDP formulation whereas in [16], [17], the authors considered a one stage formulation where the throughput of SU is maximized under the constraint that detection probability should be no less than a given level. For the multiple channel case, analytical characterization of the tradeoff between channel sensing time and DSA throughput is more challenging; only limited numerical results have been reported.…”