A non-regenerative repeating digital microwave radio system

The authors present a nonregenerative repeating system using digital quadrature amplitude modulation (QAM) signals. The difference in cumulative degradation characteristics between regenerative and nongenerative repeating systems is discussed. In addition, the bit error rate performance of a repeater transmission is presented using 16-QAM signals at a 12.5-Mb/s transmission rate. Multirelay degradation factors and countermeasures against interference noise are considered, which are self-interference passing adjacent channels and cross-polarization interference. Calculated and experimental results using adjacent 16-QAM signals and dual-polarization 256-QAM signals are presented.<
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