Investigations on Enhancement Techniques for Sparse Code Multiple Access Based Wireless Systems

Abstract

The recent evolution in wireless communication systems has established goals for high data rate, spectral efficiency, low error rate, and low latency. It is challenging to achieve these due to severe time-variance or significant frequency selectivity of radio channels. Several multiple access schemes like Code Division Multiple Access (CDMA) and Orthogonal Frequency Division Multiple Access (OFDMA) are being used in the current generation of wireless networks. The CDMA lacks performance due to Multi-path Interference (MPI), and OFDMA has no coherent frequency diversity and suffers from adjacent cell interference. To overcome the drawbacks and enhance the performance, a combination of CDMA and OFDMA has been chosen for this research, known as Orthogonal Frequency and Code Division Multiplexing Access (OFCDMA). In OFCDM, the two-dimensional (2D) spreading employed gives diversity in both time and frequency domains. This provides flexible transmission rates due to time and frequency spreading by changing the spreading factors and can work in different cell environments and channel conditions newline