Patent ID: 8938015
Filing Date: 2015-01-20
Classification: H04L

Abstract:
1. A system for resolving cyclic ambiguity in an orthogonal frequency division multiplexed (OFDM) modulated received signal, said system comprising: a demodulator configured to receive an OFDM modulated signal over a channel, said signal comprising a sequence of symbols, each of said symbols comprising one or more pilot carriers and one or more data carriers; a time filtering and interpolation circuit coupled to said demodulator, said time filtering and interpolation circuit configured to estimate the frequency response of said channel based on time filtering and interpolation of said pilot carriers; a phase slope correction circuit configured to apply each of a plurality of phase slope corrections to said frequency response and to said data carriers; a frequency filtering and interpolation circuit configured to calculate frequency response estimates of said channel at data carrier frequencies based on frequency filtering and interpolation of said phase slope corrected frequency response; an equalization circuit configured to equalize said phase slope corrected data carriers based on said calculated frequency response estimates; an error calculation circuit configure to calculate the mean square error between said equalized data carriers and a nearest QAM constellation point; and an iterative phase slope optimization circuit configured to select the phase slope correction associated with the minimum of said mean square errors, wherein said selected phase slope resolves said cyclic ambiguity.