Performance of pilot symbol assisted and PLL phase noise estimation and compensation for high-order circular QAM

Abstract

Recently, we proposed a high-order circular quadrature amplitude modulation (QAM) constellation scheme with a high low-density parity-check (LDPC) coding rate that is suitable for partial LDPC coding associated with parallel double Gray mapping for microwave mobile backhaul. This paper presents the bit error rate (BER) performance of circular QAM when using a combination of Wiener filter based pilot symbol assisted (PSA) and phase locked loop (PLL) phase noise (PN) estimation and compensation methods. Computer simulation results show that the required received signal-to-noise power ratio (SNR) at the BER of 10−6 using the PSA and PLL PN estimation and compensation is decreased by approximately 0.3, 0.6, and 1.3 dB for the pilot symbol insertion interval of 25, 50, and 100 symbols, respectively, compared to that using only the PSA PN estimation for circular 1024QAM. Accordingly, we show that the PLL PN estimation is effective in decreasing the pilot symbol overhead of PSA PN estimation for circular QAM, which is robust against time-varying PN.