The present document defines technical parameters for a high capacity Digital Radio Relay System (DRRS) operating
in frequency bands with 40 MHz channel spacing e.g. the 4 GHz, 5 GHz, U 6 GHz and 11 GHz bands. The capacity
should be STM-4 or 4 × STM-1 per 40 MHz RF-channel by using both polarizations in the co-channel dual polarized
(CCDP) mode of operation.
The area of application of these DRRS is foreseen to be in regional and trunk networks forming part of a SDH-network
including STM-4 rings.
Systems considered in the present document should be able to respect ITU-R high grade performance objectives.
The systems considered should operate in these networks having regard for existing hop length, which are considered to
be normally up to about 30 km to 40 km for regional and about 60 km for trunk networks, respectively. Hop lengths
greater than this latter length are used in special applications.
For information about compatibility with other systems see clause A.3.
The parameters specified fall into two categories:
a) Those that are required to provide compatibility between channels from different sources of equipment on the
same route connected to separate antennas.
NOTE: Equipment supplied by different manufacturers on the same path or existing radio-relay systems operate
on different frequencies.
b) Parameters defining the transmission quality of the proposed system.
The standardization deals with baseband and RF characteristics relevant to SDH. Antenna/feeder system requirements
are also considered.
Baseband interfaces have to be considered for STM-1 signals and STM-4 signals in accordance with
ITU-T Recommendations G.707 [6] and G.957 [21] respectively.