Error detection in diffusion-based molecular communication

Despite the recent research activities in molecular communication among bio agents, the design of reliable schemes remains an open problem. One of the challenges is to develop suitable coding schemes which meet the molecular communication specific constraints in terms of reliability and complexity. In this paper, we consider diffusion-based molecular communication in which the information is encoded into the concentration (e.g., on/off keying). Such a communication system operates over a completely asymmetric channel where one of the bits can be transmitted without any error while the other can undergo a random error by the channel. Because of the limitations of bio agents, we focus on error-detecting schemes which require far less complexity at the receiver relative to error-correction codes. We model the detection process at the receiver via an erasure channel and propose an algorithm that obtains the optimal codewords efficiently. Then, we consider an error-free sub-family of such codes, namely constant weight codes, and propose an implementation specific to the molecular communication. We analyze the rate of the constant-weight coding scheme and specify the optimal weights and lengths of such codes. We also show that this coding scheme, by design, would enable the nodes to synchronize their communications.