Reception and transmission power gains control in a point-to-multipoint system

摘要

A point-to-multipoint radiocommunication network comprises master stations and subscriber slave stations, each master controls a pool of slaves generally fixed at different distances from the master, some user terminals can be connect at each slave by wire/cable/fibre optic. The master acquires and stores the main configuration and operational parameters of the slaves, in particular the distances from the master. Both the master and the slaves include transmission and reception AGC circuitry suitable to counteract fast-varying unforeseeable multipath fading (Rayleigh) and rain fading and a larger but calculable free-space attenuation due to the spread of the distances. Unforeseeable fading need fast-dynamic AGCs while calculable attenuation need semistatic AGCs. The master is continuously monitoring the access channels in uplink in order to detect the access requests from the slaves. As soon as the slave station is switched on to have access to the network, the master will start those operation usually named "registration" or "ranging" or "sign-on". Up to this point the slave station is able to decode the downstream signal and to set a rough value of the upstream transmission level, but the receiving and transmitting semistatic gain/attenuation levels are not correctly configured to make the dynamic range properly counteract all the possible fading phenomena. When the master station receives a signal transmitted by the slave station, it transmits a distance information to the remote slave station; the distance may be retrieved from an installation database or calculated during the registration phase or at the initial transmissions of the slave station, according to different possible embodiments. The slave station uses the distance information to automatically configure the "semistatic" gain/attenuation level in the best way. The same concepts apply to the point-to-point radio relay systems (fig.4). <IMAGE>