Analysis of Frequency Offset, its Distribution and its Impact on Multicarrier Spread Spectrum Techniques

Multi carrier is the utmost technology before preceding towards 5G. Code Division Multiple Access (CDMA) is a basic spreading technique. Multi Tone CDMA (MT-CDMA), Multi Carrier CDMA (MC-CDMA), and Multi Carrier Direct Sequence CDMA (MC-DS-CDMA) are three types of Multi Carrier Spread Spectrum (MCSS). Carrier frequency offset (CFO) is one of the factors, which give birth to MAI and ICI. These interferences deteriorate the Spectral Efficiency(SE) of the network. Interesting fact is CFO among the subcarriers, spectral efficiency will increase with increase in the CFO. In this paper, we have compared two distributions of CFO "truncated-Gaussian, and uniform ". There is a significant increase in the performance of MCSS with increase in the variance of CFO. Another interesting fact, spectral efficiency also increases with increase in the SINR and number of interferers. Conclusively uniform Probability Density Function (PDF) of CFO outperforms truncated Gaussian PDF of CFO in all the three cases.