Wireless repeater with equalization of feedback channel and phase noise for LTE-Advanced uplink

When the gain of a wireless repeater is larger than the isolation between transmit and receive antennas of the repeater, the feedback signal that comes into the receive antenna from the transmit antenna of the repeater causes the repeater to go into feedback oscillation regardless of the input signal. In this paper, we propose adaptive equalizer and phase noise compensator in order to effectively cancel feedback channel and phase noise in wireless repeater system based on LTE-Advanced uplink system. In a repeater system, the performance has got worse caused by feedback channel and phase noise. Thus, the interference cancellation system requires to removing the interference signal in wireless repeater. In this paper, in order to cancel feedback channel, we use adaptive equalizer such as NLMS and RLS. And, in LTE-Advanced uplink standard, block type pilot is a common pilot pattern in wireless communication systems. So the phase noise compensator exploits block type pilot. Instead of estimating phase noise in other algorithms, which are pretty difficult and complex to get accurate estimation results, the proposed method directly estimates the interference components caused by phase noise and improves estimation accuracy. After that, we reconstruct the interference matrix and suppress the interferences by the inverse matrix method. BER performance of proposed method is satisfied 12.5dB at 10-4.