Improved Phase Noise Compensation in OFDM Systems

. Phase noise (PN) consists of common phase error (CPE) and inter carrier interference (ICI). In an OFDM symbol, CPE has the same impact on each subcarrier, which is easy to be suppressed. However, ICI destroys the orthog-onality of subcarriers, which is difficult to be eliminated. Therefore, an additional method is needed to be performed in the OFDM receiver to compensate the ICI. The interpolation method is considered an effective way to eliminate the ICI caused by PN in the OFDM system. To enhance the accuracy of the PN estimation and compensation, we propose a linear method, LI-ICI-EE1 method based on LI-ICI-E1. Multiple interpolation slopes are first calculated by selecting multiple pairs of observation samples, then the slope with the maximal linear fitting degree based on the least square (LS) criterion is selected to improve the LI precision. Fur-thermore, to improve the estimation accuracy of PN in the LI-ICI-EE1, we propose a Shrinkage-based on LI-ICI-E1 method named SLI-EE1, which is implemented by adding an 𝑙 2 norm penalty term to the error function. At last, to optimize the low accuracy of LI-ICI-EE1 and SLI-EE1 when the PN compensation problem is a high-order problem, we propose a non-linear method Shrinkage-based Third-order Lagrange method named STL. Simulation results show that the improved methods have better BER performance.