Pre-interference canceller for digital microwave radio systems

✍ Scribed by Kazuji Watanabe; Syuta Uwano; Hideaki Matsue

• Publisher: John Wiley and Sons
• Year: 1995
• Tongue: English
• Weight: 853 KB
• Volume: 78
• Category: Article
• ISSN: 8756-6621
• DOI: 10.1002/ecja.4410780609

✦ Synopsis

As radio communication has progressed, reduction of intersystem interference has become a problem. In a conventional interference canceller, the interference signal as a source of cancellation is obtained at the receiving station and the interference component in the desired signal is canceled based on this interference signal. However, the interference signal for cancellation may not be obtained at the receiving station. As a remedy, an extraction and reinjection-type interference canceller has already been proposed.

In this paper, a pre-interference canceller is proposed in which, if the transmitting station of the desired signal and that of the interference signal are identical, the interference signal is mixed with the desired signal from the transmitting station beforehand and the interference signal leaking into the desired signal is cancelled at the receiving station.

First, the applicable range and the fundamental configuration of the present canceller are presented. Subsequently, the method for determining the amplitude and phase of the interference signal injected into the desired signal of the transmitting station and the method for evaluation of the cancellation effect are presented theoretically.

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Next, an experiment is carried out with the desired signal of 16 QAM or 256 QAM and the interference signal of 256 QAM.

Interference improvement by about 20 dB is obtained for both the 16 and 256 QAM signals. Also, the response speed of control for the fading is 60 ms. In addition to the validity of the theoretical results, effectiveness of the proposed canceller is shown.