Due to dramatic increases in data traffic over the last decade, there has been growing interest in enhancing system performance levels in data communications and networking. Moreover, data are represented in various digital forms, such as text, voice, or video. As data capacity continues to increase, it imposes ever-demanding requirements on data-processing capabilities and networking system architectures. The desired system characteristics include, but are not limited to, lower power consumption, minimized networking latency, higher spectral efficiency/throughput, and enhanced data security. This Special Issue highlights research efforts dedicated to addressing the technical challenges faced in the broader data communication field, focusing on original system and algorithm approaches, which can enhance state-of-the-art techniques for communication and networking.