DLCs are used in telecom networks to extend the subscriber services available at the Local Exchange ( here-after referred as LE) to remote places where the subscribers are located. As the name implies, it uses digital techniques to carry voice and data information of subscribers.

Telecom Network expansion is easily achieved by deploying DLCs which facilitate provisioning of new connections on demand. The system is very useful for providing digital as well as analog services without compromising on the quality and bandwidth requirements. With V5.2 Interface (a protocol defined by the ITU-T), the DLC acts as a 'Remote Subscriber Unit' supporting concentration of Telecom traffic. The system includes all the resources like Power Plant, MDF, DDF etc., required for a emote exchange. These remote units can be of Indoor or Outdoor or Wall-mount types. These units can be installed in the colonies, commercial buildings, village clusters.etc and are connected to the main exchange through Optical Fiber cables.

• Type-1: Integrated with interface to LE at the level of 2Mbps with V5.2 interface.
• Type-2: Universal with interface to LE at 2-Wire interface

Typical architecture of the Digital Loop Carrier (DLC) on SDH STM-1 Ring consists of network elements - a Central Office Terminal (COT) and a set of remote terminals called Access Terminals (AT) all interconnected on 2-fibre SDH STM-1 Optical Ring. The system is configured in a RING topology with TWO aggregate optical ports at each terminal. The COT which forms the hub located at LE end consists of STM-1/4 Multiplexer deployed in the Add-Drop mode. The AT, deployed at the remote-end wherever there are subscriber clusters, consists of STM-1/4 De-multiplexer in Add-Drop mode. There can be a max 15 ATs in a RING. They drop the required bandwidth contained in the aggregate STM-1/4 signal at each of the ATs and handle different types of user interfaces for connecting the subscriber equipment to the network. Each AT can provide a max of 480 PSTN subscribers or combination of different subscriber interfaces.
The equipment is supplied with Element Management System software to execute all kinds of configuration, monitoring activities for individual RING and Network Management System software to monitor the total network of deployed DLCs and with remote management. Both EMS and NMS have extensive GUI and they are SNMP compliant.

In the emerging higher-end existence of Internet developments and technological advancements of today, the users are on the look out not only just for Voice connectivity alone, but also for high-speed Internet access, Video-on-Demand etc. This trend necessitates deployment of new network layout. However, in order to reduce the cost of the network building / maintenance and for better service facilities there is a need to deploy the "Convergent Network", which supports all these services that the user is looking for. That is where MIC Electronics - who already possesses the expertise in designing, developing and deploying the Digital Loop Carrier System - are in the forefront again with MIC's Multi Service Access Network which meets all the functional requirements to offer "Tripple Play" services - voice, video and data.

MSAN-20 is a Multi-Service Broadband Access Network on STM-1/4/16 SDH Optical Ring for the next generation network. It is mainly for metro-access applications, comprising of both narrowband interfaces as well as broadband interfaces on the same platform as shown in the figure. The narrowband interfaces include - circuit-switched and leased-line interfaces. The broadband interfaces include Ethernet, ADSL, etc., for services like High Speed Internet Access, Gaming, Video-on-Demand, Broadcast Video services, etc.

The equipment is supplied with Element Management System software to execute all kinds of configuration, monitoring activities for individual RING and Network Management System software to monitor the total network of deployed DLCs and with remote management. Both EMS and NMS have extensive GUI and they are SNMP compliant.