A Non-Negative Code Division Multiple Access in Nanonetwork Based on Non-Uniform Quantization

With the advancement of nanotechnology, the Bio-Internet of Things(B-IoT) and nanonetworks have become important research focuses. Compared to electromagnetic communication, molecular communication is not constrained by device size and has outstanding low-power consumption and biocompatibility, making it a promising approach for realizing nanonetworks. However, when multiple nanomachines are present, using the same type of information molecule leads to severe inter-user interference. Since the available types of information molecules are limited, simply increasing their number is not feasible and also raises the detection complexity at the receiver. In this paper, we propose a non-negative signal-based code-division multiple access (NCMA) scheme that enables communication among multiple nanomachines using only one type of information molecule. By assigning unique orthogonal codewords to different users and employing a non-uniform sampling and quantization scheme, the proposed NCMA effectively distinguishes information from different users and enhances interference resistance. Simulation results demonstrate that this scheme can support up to 16 nanomachines communicating with each other using only a single type of information molecule, while significantly reducing inter-symbol interference, making it a viable and effective communication solution for B-IoT.