The horizontal structure of rain and its impact on the design of advanced satellite systems at centimetre and millimetre wavelengths

Abstract

The paper deals with the severe propagation problems that wiill be probably encountered in designing the future satellite communication systems in the Ka band and above and with some possible advanced solutions based on the knowledge of the local climatology. Within the very wide spectrum of new envisaged systems two ]particularly significant examples have been selected: the TV-sat at 22 GHz and the feeder-links at 20-30 GHz when site diversity configurations will be necessary as expected with low elevation orbiting satellites. As shown in the paper, by exploiting to the maximuIn extent the available meteorological informations, very effective fading and power-saving countermeasures can be envisaged.The enormous importance acquired by the satellite in some future t e l e c o~~~~c a~i o n systems like the direct TV broadcasting or the radio mobile is under the everybody's eyes; ong the various reasons of this s8uccess, the principal one undoubtly i s the ease to cover, with relatively IOW costs and in short time, very extended a e a s while keeping an e J ;~a o r d i n~ service flex ity. However, owing; to the greatly increased demand of tlransmission capacity (now and for the future), probl arise to cope with shortage of banwidth and orbital arcs, and with control of the EM interference and it is expected to become harder and harder in the next future.

An investigation of site diversity and comparison with ITU‐R recommendations

“…A key parameter in the calculation of diversity gain and improvement is the distance between the two sites in the site diversity system. This is hardly surprising, as it is well known that the rain rate values at two points in space becomes decorrelated with increasing distance between them [ Paraboni et al , 1998]. According to ITU‐R Rec.…”

The effect of precipitation on microwave LMDS networks-performance analysis using a physical raincell model

“…For we can use a log-power model, which is easily differentiable, such as (9) where , , and can be adjusted so that (7) fits the local long-term rain statistics. A table with appropriate values [6] for each "old" ITU-R rain zone is given in Table I. In general, is chosen so that % for mm/h, the gen-erally accepted value for the overall probability in many places in Europe.…”

“…Starting from (6) and 7fitted to the local rain zone, a cell density is generated. The assignment of the raincells (random coordinates of the raincell centers within the area considered, each having a random "diameter" and peak intensity ) is performed as follows.…”