SG 9 covers radio-relay systems – point-to-point terrestrial links, both LOS and OTH. It addresses such topics as performance and availability objectives, RF channel arrangements, system characteristics and fade countermeasures.
SG 9 also deals with fixed systems below 30 MHz, for which there is still a surprisingly high usage.
A third, and greatly expanding area dealt with by the SG is that of FWA. This includes systems such as those providing the “last mile” connection to the home, point-to-point and point-to-multipoint distribution systems – all of which span a wide range of requirements in terms of data rate and performance objectives.
Finally, a fourth and very important topic dealt with by SG 9, not unconnected with the theme of FWA, is the exciting topic of HAPS.
