Fast detection of OFDM systems using graphical models

In this paper, we investigate the effect of four different message schedules on the performance of an OFDM receiver with unknown carrier frequency and phase noise offsets. One of the methods uses a serial schedule and the remaining three techniques use non-serial message schedules. The serial schedule is shown to give good estimates in less number of iterations compared to the non-serial message schedules. The results also show that fast graphical estimators can be designed by using non-serial message schedules with damping to approach the bit error rates of the serial schedule while reducing the computational time for convergence. In particular, the damped flooding message schedule using four iterations reduces the computational time for convergence by more than 30 % compared to the serial message schedule using one iteration for signal to noise ratios lower than 20 dB.