Maurizio Bolla

A new 32QAM modem for doubling transmission capacity in 40 MHz channelling plans

Frequency reuse enables one to double spectrum efficiency of radio systems. This technique is of great interest for microwave bands below 10 GHz, which are now fully occupied by conventional interleaved channels. The first step is frequency reuse of 40-MHz channel arrangements, which typically use 16 quadrature amplitude modulated (QAM). 140-Mb/s systems. A 32QAM system equipped with a baseband cross polarization interference canceller (XPIC) which may be used with the same structures of the installed 16QAM radios with no loss in performance is proposed. Future 32QAM modulation will also be possible for synchronous STM1 155.52-Mb/s signals. The hardware implementation of a 32QAM modem, including measurement results, is presented.<<ETX>>