On code design for simultaneous energy and information transfer

We consider the problem of binary code design for simultaneous energy and information transfer where the receiver completely relies on the received signal for fulfilling its real-time power requirements. The receiver, in this scenario, would need a certain amount of energy (derived from the received signal) within a sliding time window for its continuous operation. In order to meet this energy requirement at the receiver, the transmitter should use only those codewords which carry sufficient energy. In this paper, we assume that the transmitter uses on-off keying where bit one corresponds to transmission of a high energy signal. The transmitter uses only those codewords which have at least d ones in a sliding window of W = d + 1 bits. We show that with this constraint, the noiseless code capacity is achieved by sequences generated from a finite state Markov machine. We also investigate achievable rates when such constrained codes are used on noisy communication channels. Although a few of these results are well known for run-length limited codes used for data storage, they do not seem to appear in literature in the form presented here.