Experiments on Frequency Error Compensation Using Synchronization Channel in OFDM Radio Access

This paper experimentally investigates the effect of frequency error compensation provided by demodulation automatic frequency control (AFC) using the Synchronization Channel (SCH) in downlink OFDM radio access. The implemented OFDM receiver compensates for the frequency error caused by the difference in frequency between a base station (BS) and a user equipment (UE) using a time-division multiplexed SCH signal and that caused by the Doppler shift generated by the mobility of a user using reference signals with staggered multiplexing. Experimental results show that even when the standard oscillator frequency of the UE cannot be made to track the more accurate frequency of a BS, demodulation AFC can suppress the residual frequency error to a sufficiently low level, i.e., within 0.3ppm, using the SCH so that the degradation in the block error rate of the physical broadcast channel control signals is slight, i.e., within approximately 0.1dB, with respect to the case without frequency error for speeds greater than 350km/h.