From Gigabit to Multi-Gigabit: mm Waves in Mobile Networks´ Backhaul

In recent years mm-wave point-to-point radios appeared among wireless equipment. The large available bandwidth in principle up to 10 GHz - the sparse utilization of the frequency band and efficient spatial filtering make them very advantageous for the backhaul of cellular networks. Present day equipment transmit 1 Gbit/sec over paths of several, about 1 to 3 km-s. The aim of this paper is to briefly present features and applications of these equipments and to discuss development possibilities. Concerning the increase of hop length the already used technique of rate adaptation is analyzed and two diversity techniques are presented. About increase of transmission rate up to 10 Gbit/sec it is shown that simply rescaling the methods used in actual systems is virtually non-viable and more sophisticated methods are needed. Two techniques are proposed and investigated, (i) Spatial demultiplexing of channels is presented; conditions of application are shown, (ii) Possibilities offered by adaptive coding are investigated.