Performance investigation of CMA and RLS based equalization for next generation long reach passive optical networks

Digital coherent receivers (DCR) exploiting advanced digital signal processing (DSP) have shown major impact, in terms of increasing receiver sensitivity and spectral efficiency, on optical communication for long haul transmission. Recently coherent receivers started to be employed in metro/access networks. In this paper, we investigate the performance of DCR in next generation long reach passive optical networks (NG-LRPON). Constant modulus algorithm (CMA) and recursive least squares (RLS) equalizers are used to blindly mitigate fiber chromatic dispersion (CD) and polarization mode dispersion (PMD) for different signal speeds and modulation schemes. For low signal speed, our simulation results show that CMA achieves same steady state as RLS however with low complexity. For high baud rate signals such as 5 and 10Gbaud, RLS achieves 50% faster convergence rate in terms of number of symbols.