A Comprehensive Review on Multiple Access Schemes for URLLC Applications

Meeting the requirements of spectral efficiency and massive connectivity are facing a major challenge in current standards of cellular network. To overcome this bottleneck, multiple access schemes are being chosen as a novel candidate. Orthogonal Multiple Access scheme, Non Orthogonal Multiple Access scheme and its variants have been explored reduced latency and increased connectivity. Out of these two schemes, Non orthogonal based multiple access is being suggested for 5G and beyond systems to occupy more number of subscribers. But, present mobile communication systems require high quality of service with minimal latency. Polar codes a class of channel codes, offer several advantages when combined with Non Orthogonal Multiple Access techniques. These codes have shown a potential interest to prove the capacity of wireless communication systems. The recent error correction techniques are focusing towards in proving less computational complexity with better reliability. To satisfy the above requirements, the polar coded NOMA scheme along with Guessing Random Additive Noise Decoding scheme would be proposed. In this article, various multiple access schemes have been taken into account and are reviewed at different situations to achieve Ultra-reliable low latency communication (URLLC) problem specifications in 5G and beyond systems.