Advanced techniques for super multi-carrier digital microwave radio with trellis-coded 256 QAM modulation

The latest techniques for realization of an outage-free digital microwave radio (DMR) are presented. Three major techniques, trellis-coded 256 QAM (quadrature amplitude modulation) modulation, super multicarrier transmission, and microwave signal processing (MSP), are described. The BER (bit error rate) and signature characteristics of the trellis-coded 256 QAM system are simulated, and its validity as a fading countermeasure is indicated. The Viterbi-decoder LSI and effect of phase error on the TCM modem are also presented. An experiment using a 4, 8, 40-carrier 256 QAM modem showed an overall outage improvement factor of nearly 500 times due to a 40-carrier system. Lastly, the microwave signal processing technique, including IF stage (carrier) signals for DMR systems, is presented. An all-digital 256 QAM modulator was constructed and showed superior performance with no adjustment.<>