Dss «Kvant-e». Analogue customer unit borscht function.
An analogue customer unit performs BORSCHT functions listed below.
Battery feed for a phone.
Overvoltage protection prevents equipment from being affected by high voltage or current.
Ringing.
Supervision function is vital for sensing “on/off-hook” states and dialing.
Coding, A/D and D/A conversions.
Hybrid function refers to the transition from 2-wire input to 4-wire output.
Testing function is necessary to test parameters of a subscriber line and a customer unit.
Dss «Kvant-e». Subscriber access subsystem. Slu-128 scheme. Short description of main elements.
"Kvant-E" system exchanges are intended for operation as a host exchange (HE), host and transit exchange (HTE), call center of an urban telephone network (UTN) or as a central exchange (CE), nodal exchange (NE), terminal exchange (TE) of a rural telephone network (RTN). Kvant-E digital switching system provides up to 100000 ports for subscriber access. Capacity of a subscriber module ranges from 128 to 640 ports. Kvant-E digital switching system is capable of providing 25 additional services.
Equipment of any digital switching system can be classified to the definite subsystems. Subscriber modules and remote subscriber modules belong to narrowband access subsystem while base stations controller (BSC), base stations, fixed access units (FAU) and repeaters belong to a wireless access subsystem. Switching subsystem is represented by all the channel switches of the Kvant-E. For example, switching control unit (SCU) belongs to the switching subsystem. Control subsystem is represented in the figure 2.1 by the control devices (CD). Module of synchronization provides generation and distribution of synchronization signals. MCCS7 is a module that enables SS7 signaling capability for the digital switching system. Digital line units (DLU) also called digital trunk units (DTU) belong to a network access subsystem. Operation administration and maintenance subsystem is represented by technical maintenance center (TMC) equipped with technical maintenance indicators board (TMIB).
A narrowband access subscriber module supports analogue subscriber lines, concentrates subscriber traffic, and provides subscriber and inner-system signaling exchange. Structure of the narrowband access subscriber module is shown in the figure 2.2.
Figure 2.2 – Narrowband access subscriber module of Kvant-e
The subscriber module contains a time and space switch. The switch handles 8 E1 trunks. The 0 trunk is assigned to signaling and synchronization unit (SSU) that provides signalling exchange and traffic transmission towards SCU. Trunks 1 to 4 are assigned to the cards of customer units (CU) (every customer unit is assigned to a single time channel). The 5-th trunk is assigned to a testing unit (TU). The 6-th trunk is assigned to the digital attenuator (DA). The 7-th trunk is shared by a digital receiver and a digital generator of tone signals (DGTS).
Signaling and synchronization unit (SSU) connects a subscriber module to a switching control unit (SCU) of host equipment. The SSU retransmits (in TC-0) synchronization signals received from the module of synchronization (MS). The SSU provides and supports inner-system signalling channel.
CS-8A controller controls the whole subscriber module. It receives and processes address information form a phone or SCU’s controller. It interacts with a controller of SCU of HE via inner-system signaling channel (ISSC). It controls operation of TSS and other units of the SM.
Generator of ringing signal (Ring) generates the 25 Hz AC ring signals in order to inform a subscriber about incoming call.
Testing unit (TU) measures parameters of subscriber lines and customer units. Digital attenuator (DA) provides attenuation of 6 dB for a voice transmission path. The DA is needed for autonomous operation of the module. If a call transits HE then SCU of host equipment provides attenuation.
Digital receiver (DR) receives DTMF dialing from a subscriber terminal.
Digital generator of tone signals (DGTS) generates tone signals that are necessary for any peripheral device operation. Moreover, it supports one voice message.
Subscriber traffic leaves the subscriber module and enters the switching control unit. The switching control unit is the digital switching network of Kvant-E.
A narrowband TDM digital switching network transfers information from any time channels of any input lines to any time channels of any output lines according to address information.
The SCU is capable of supporting from 16 to 512 E1 trunks. We are going to look at two SCU modules. They are SCU 32 and SCU 128.
Let us take a look at SCU-128 of Kvant-E digital switching system. Blok diagram of the SCU-128 is given in the figure 2.4.
Figure 2.4 – Block diagram of SCU-128
The switching control unit in the 128x128 configuration is a fully accessible, backed up TS type switch. It makes sense to use SCU-128 at a host exchange. SCU128 supports 128 E1 trunks (2 Mbit/s) connected to the multiplexers. The multiplexers multiplex 128 2 Mbit/s streams to 32 8192 kbit/s flows towards TSS. SCU-128 has eight multiplexers and eight demultiplexers. Every multiplexer or demultiplexer supports 16 E1 trunks.
Switching matrix supports 32 8 Mbit/s trunks. Every 8192 kbit/s trunk has a separate 2048 kbit/s trunk for signaling. Such a trunk carries 16-th time channels of all the 16 E1 trunks connected to a single multiplexer. Microcontroller (MK7L) processes signaling information from signaling trunks. Microcontroller is connected to a controller (PCA-6145B) via synchronous HDLC (High Level Data Link
Controller) trunk.
SCU-128 (Switching Control Unit)
SCU-128 is a fully accessible switching unit of the TS type. It is backed up. SCU-128 performs time and space switching.
It makes sense to use SCU-128 at host exchange. SCU-128 supports 128 E1 trunks (2 Mbit/s) connected to the multiplexers. The multiplexers multiplex 128 2 Mbit/s streams to 32 8192 kbit/s flows towards TSS. SCU-128 has eight multiplexers and eight demultiplexers. Every multiplexer or demultiplexer supports 16 E1 trunks.
Switching matrix supports 32 8 Mbit/s trunks. Every 8192 kbit/s trunk has a separate 2048 kbit/s trunk for signaling. Such a trunk carries 16-th time channels of all the 16 E1 trunks connected to one multiplexer. Microcontroller (MC7L) processes signaling information from signaling trunks. Microcontroller is connected to a controller (PCA-6145B) via synchronous HDLC (High Level Data Link Controller) trunk.
Kbit/s
PCA-6145B
MC7L
TC
TC
TC
TC
Mbit/s
Kbit/s
Kbit/s
Kbit/s
MX
DMX
MS
Figure 15 – Structure of SCU-128
Function of a broadband switching network is to perform ATM or Fast Packet Switching or Ethernet switching. It performs packet switching of digital flows with different bit rates (2 Mbit/s, 622 Mbit/s up to 1 Gbit/s). Asynchronous digital switching networks have inner buffer memory to store packets. Procedure of buffering can be implemented as input buffering, output buffering, or a switch can use a centralized buffer.