Fully adaptive MODEM up to 1024 QAM for 26 GHz broadband fixed wireless access systems with mesh topology

Broadband fixed wireless access (BFWA) systems operating above 17-GHz band are suitable for high-density deployment of high capacity wireless access infrastructure, while the radio link quality can suffer from rain attenuation especially in rainy climatic regions. In order to overcome the problem and enhance not only the reliability but also the total capacity of the system, the authors have proposed a multi-hop BFWA system with mesh topology. Its unique characteristics include the modulator/demodulator (MODEM) that can adaptively support QPSK, 16 QAM, 64 QAM, 256 QAM and 1024 QAM operation. It has the maximum transmission capacity of 52 Mbits/s per channel at 6.75 MHz symbol rate and attains 364 Mbits/s by multi-channel configuration over the entire 60-MHz bandwidth at 26-GHz band. This paper presents design and implementation of the MODEM together with various data including bit error curves that demonstrate the validity of the design and implementation. A one-year field experiment commenced in April 2004.