ETSI - ETS 300 234
Transmission and Multiplexing (TM); High Capacity Digital Radio-Relay Systems Carrying 1 x STM-1 Signals and Operating in Frequency Bands with About 30 MHz Channel Spacing and Alternated Arrangements
|Publication Date:||1 January 1995|
This European Telecommunication Standard (ETS) specifies parameters for digital radio-relay systems with a channel capacity of 1 x Synchronous Transport Module-level 1 (1 x STM-1) designed to operate in defined bands up to 15 GHz utilising approximately 30 MHz between adjacent cross-polar channels.
The parameters specified fall into two categories:
a) those required to provide compatibility between channels from different sources of equipment on the same route, connected either to separate antennas, or to separate polarizations of the same antenna. This category also includes parameters providing compatibility with the existing radio-relay network;
b) parameters defining the transmission quality of the proposed systems.
The task of defining compatibility requirements with analogue and digital systems on the same hop and at nodes is made complex by the fact that analogue systems and some digital systems are not standardized. Compatibility requirements are, therefore, limited to allowing the operation of digital and analogue channels on separate ports of the same antenna.
The standardization includes the following specifications:
- transmitter and receiver characteristics;
- baseband and Radio Frequency (RF) interface characteristics;
- diversity system characteristics.
Two possible baseband interfaces have to be considered:
- one for STM-1 signals (electrical and/or optical) in accordance with ITU-R Recommendation 750; and
- one for 140 Mbit/s plesiochronous signals (only electrical), according to ITU-T recommendation G.703.
The 140 Mbit/s signals should be carried "open-port", i.e. in a transparent manner independent of their content. They should be mapped into a 155 Mbit/s STM-1 signal as described in ITU-T Recommendations G.708 and G.709.
As regards the STM-1 signal the Section Overhead (SOH) processing is covered in a separate ETSI STC TM 4 document (a report on Synchronous Digital Hierarchy (SDH) aspects) and in ITU-R Recommendation 750 .