High-Capacity Millimeter-Wave Transmission System

Fixed wireless system (FWS) is mainly used in mobile network systems. As an RF band of the FWS, the microwave bands (6–42 GHz) have been used so far; however, the millimeter-wave band (60–175 GHz), which can realize a large capacity by widening the bandwidth, is now being commercialized. In this chapter, elementary modem technologies in the FWS are introduced. In particular, phase noise suppression, which is a key to realizing high-order modulation scheme and millimeter-wave bands, is explained. Regarding the millimeter-wave bands, regulations for the FWS and the propagation characteristics such as the rainfall attenuation indicated by the ITU-R recommendations are introduced. Moreover, multiplexing transmission technologies for realizing further high-capacity, especially spatial multiplexing transmission technologies suitable for the millimeter-wave bands, which has been attracting attention in recent years, are explained, and as a target of the near future, specifications for realizing a 100 Gbps transmission system using the multiplexing technology are described.