The unit carries out the following functions:
● 32xE1 external tributary interfaces (public interface) are available on the 32xE1 board front
panel. They carry 32xE1 tributary signals. E1 interface is compliant with ITU-T G.703 re- commendation. The impedance is both 120 ohm and 75 ohm, with a unique hardware ver- sion using four mini RJ21 connectors. The different impedances are provided via different cabling on the same connector. Each E1 uses six pins (three for Tx signals and 3 for Rx signals: in each direction a pin is used for both impedances and the other two pins are mu- tually exclusive).
● Physical interface management, which is in charge of auxiliary channels (User/D exter-
nal/Alarms) interfacing. Concerning 32xE1 management, a clock recovery function of input tributaries is available. Each tributary can be enabled or disabled. When a tributary is disabled, an AIS signal is transmitted at output port. When a tributary is enabled, hardware provides fault monitoring associated to each tributary, including AIS IN, LOS, Code error and AIS OUT detection. An interface towards the control section for configuration setting and alarm reporting are provided. For test and maintenance purposes, local loopback are available on each tributary signal, to verify interface and cabling integrity. Lightening pro- tection is provided. For test and maintenance, Access Board allows local and remote loop- back for each tributary signal.
● Cross connect function allows to cross-connect up to 32xE1 signals. Each local E1 input
port can be switched to any E1 tributary output port, at the other side of the link. Cross con- nect E1 configuration is set by using of suitable software commands, issued via LCT or EMS.
● A Stuffing/ destuffing mechanism is present for each tributary signal, in order to multiplex them into an aggregate signal.
● Multiplexing of 32xE1 tributary signals (after the stuffing block) into an aggregate frame al-
lows backplane connection. De-multiplexing of the same signals implemented in the oppo- site direction on the aggregate received from BaseBand boards.The overall functionalities associated to the access board are described in the following picture.
● Some other Auxiliary functions are available. A SEEP (i.e a Serial EEPROM) for remote
inventory (PID) is provided to record Factory Inventory data, and user data associated to Access board. This board holds the memory key receptacle, in order to allow memory key insertion and usage, and provide communication between Memory key interface and con- troller. Parallel Alarm connector allows collecting local Station alarms, to provide Remote Station controls and to provide summarized alarms associated to the local Radio Unit. In- terfacing toward the controller board, using internal communication channels. A mechani- cal ON/OFF locking lever switch for power supply control is provided.
6.5.2
BB (32xE1) Unit
The unit carries out the following functions:
● A part of "Baseband" management. BaseBand board multiplexes net payload, service
channel (64 kbit/s channel) and a TMN channel in order to build up the digital radio frame (aggregate signal) to be transmitted through the radio link. De-multiplexing of the same si- gnals, in Rx side. The radio frame is completely generated by Baseband. The multiplexed signal is FEC coded (Tx side) and Decoded (Rx side) for error correction purposes. FEC analysis of received signal is supported to allow hitless switch in protected system types and a proper CRC code is used for performance monitoring of the radio link. Signal is then Interleaved (Tx side) and de-interleaved (Rx side). Finally signal is scrambled (Tx side) to allow better RF spectrum shaping and de-scrambled (Rx side). FEC, Interleaver and Scrambler blocks can be enabled or disabled (by-passed) through a proper configuration setting.
● Baseband board supports Protection logic and switch controls, in order to manage protec-
ted 'System Types'. In particular for FD system types, a Hitless protection mechanism has been implemented, with delay compensation between the two RF channels. Compensati- on circuitry can compensate delays up to 16 bit (static portion) plus 16 bit (dynamic porti- on). Finally interfacing toward the control section for configuration setting and alarm repor- ting is required. The output of the Baseband management is the radio frame, i.e. the aggregate frame transmitted on the radio interface. The overall functionalities associated to baseband board processing are described in the following picture.
● "Power supply" block is in charge of equipment interfacing to external power supply (surge protection, EMI filtering), equipment internal power lines conditioning (soft-start, etc.) and -48 V power distribution to DC/DC converters and towards ODU. Tertiary sources genera- tion and tertiary sources' distribution (unit power sources) is foreseen. A battery redundan- cy scheme is provided. "Power supply" block provides IDU-ODU cable interface conditio- ning including Power supply signal switch off when short circuit or open circuit is detected. Detection and management of alarms related to equipment power supply system and in- terfacing toward the control section for alarm collection is provided.
6.5.3
Controller unit
The Controller unit implements a system controller, that is capable of managing all the system configurations. The main functions are:
● collection of alarms and working parameters from the system units (IDU and ODU); trans-
mission of this information to a local PC and to a network supervision system
● activation of system commands coming from a local PC or from a network supervision sys-
tem (status forcing, modification of equipment parameters, etc.)
● storage on a Memory key of the system configurations and on EEPROMs the inventory /
user data and alarms history.
● routing of messages among controllers and the network supervision system manager
● electrical and protocol translation between the radio environment (which uses a proprietary
protocol channel, embedded in the radio frame, to transport management information) and the supervision system (which requests that this information is available on a public con- nector, with a standard protocol).
6.6
IDU (1xE3)
Fig. 6.5 reports the block diagram of the IDU. The basic version (1+0) of the IDU consists of:
● a 1xE3 Tributary unit (75 Ohm unbal.), that represents the physical access of the equip-
All the other configurations of the IDU ( (1+1) FD, PD and H/S) are obtained by duplicating only the BB 1xE3 unit.
The IDU is provided with an EEPROM memory fitted on the Controller unit and of a KEY to insert onto the Tributary unit containing all the configuration parameters.