The modulator is used to perform frequency conversion on the received uplink/downlink RF signals, and the followed polarization controller and the balanced photodetector realize switching of the uplink and downlink RF channels. The RF repeater is built entirely using optical methods and does not require any frequency-dependent equipment, thus enabling high operating frequency and large operating bandwidth. In this paper, a dual-channel photonic RF repeater using polarization-division multiplexing dual-parallel Mach-Zehnder modulator is proposed. Due to frequency-dependent microwave devices, conventional electrical RF repeaters have limited bandwidth and are susceptible to electromagnetic interference.
Radio frequency (RF) repeaters are often used in satellite communication, wireless wideband communication and electronic warfare systems for signal receiving, forwarding and processing. After analyzing the proposed smart antenna module, we found out that the proposed repeater increases the amplification rate 15dB compare to the conventional RF repeater. We have designed a smart antenna module with switching beam structure in order to reduce the hardware and computational complexity.
To solve these problems, we have studied the implementation and adaptation of smart antenna system for RF repeaters. However, it requires lots of hardware complexity and computational delay.
Or, recently, ICS (interference cancellation system) techniques have been studied to estimate and to remove the feedback signals. Therefore, a receiving antenna has to be isolated from a transmitting antenna in order to reduce the effect of the feedbacked signal in the RF repeater. And the amplification rate of the RF repeater is limited by the feedbacked signals from the same repeater. The signals received at the receiving antenna are consist of signals from base station (or mobile terminal) and transmitted signals from the other side of antenna in a RF repeater.
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