High efficient transmission on digital microwave radio

Abstract

The high-capacity digital microwave radio (DMR) currently used for trunk lines has a 4.5-b/Hz efficiency using 64 QAM (quadrature amplitude modulation) modulation and transmits 135-Mbps data within a 30-MHz bandwidth. When dual-polarization transmission techniques are used, an efficiency of 9 b/Hz can be achieved and transmission of 270 Mb/s data in the 30-MHz bandwidth becomes possible. The features and configuration of a 64 QAM DMR transmission system using dual polarization are presented. It is concluded that, currently, the 64 QAM DMR with XPIC (cross-polarization interference cancellers) is the most feasible system from both the technical and economical viewpoints when a capacity of higher than 135 Mb/s is required.<>