E1 Telecom: A Global Communication Standard For Digital Voice Communication


As populations grew and telecommunications networks began to experience larger loads of traffic, a method for standardizing data transfer was needed. In the European region, a system based off of the T-Carrier system in North America was derived. This became known as the E-Carrier System, or E1 System.

This digital voice transmission format was devised by the International Telecommunication Union Telecommunication Standardization Sector (ITU-T). While the name was created by The European Conference of Postal and Telecommunications Administrations (CEPT). Now widely used around the world (except for in North America and Japan) this telecom standard has proved to be reliable and provide faster communications than that of the American standard that it was based off of.

The system of cabling in an E1 network is relatively simple. Allowing for many conversations to be carried over a single line, E1 was created to promote reliability and efficiency within the telecom industry while avoiding excessive network redundancy.

Using a method known as multiplexing, E-Carrier networks allow for up to 32 conversations to be carried over a single line. Through data packet switching and encoded transmission cues, pieces of data are sent across the network and reassembled at the other end before the receiver is able to hear them.

With a data transfer rate of 2.048 million bits per second, over 32 channels at 64/kbps each, the E1 standard exceeds the transfer rates of it's equivalent system, T1 (1.544Mbit/s over 24 channels.

How it works

An E1 link operates over two separate sets of wires, usually Unshielded twisted pair (balanced cable) or using coaxial (unbalanced cable). A peak signal is encoded with pulses using a method avoiding long periods without polarity changes. These pulses are further divided into 32 timeslots which are further broken down to 8 bits each. Each time-slot sends and receives a PCM (Pulse Code Modulation) chunk to digitally represent sampled analog signals.

This form of data-transfer allows for a rate of flow useful in voice-over and telecom applications.

While this method has been recognized by CEPT as an international standard, usage in the US, Canada, and Japan still remains low due to the high volume of data transfer over the similar networks running on the older T-carrier technology.

In many countries around the world, telecommunications tasks are increasingly being handled across a communications-standard that is known as the E-Carrier System.

Similar to the T-Carrier networks found in North America, the E-Carrier differences are rather small but significant. Performing the same tasks over a network that is essentially the same, the difference lies in the encoding and data-transfer methods. While data transfered across a T1 connection arrives "in-band" with control information and data packets are sent at along the same path, Controls and transmissions are carried concurrently in an "out-of-band" method. This allows for the "urgent" Control coding to be processed by the receiving device in order to determine what information is following on the other line, as opposed to having to demultiplex the data packets like with T1 networks.

Equipment designed to work for E1 networks must be capable of sending and receiving data in this way. By sending alarm monitoring information over an E1 link, you circumvent the need for an expansive LAN while maintaining a relatively fast connection rate.

The Need for Standards - European countries work together to establish E1

When calls have to be transported from one service provider to another, perhaps passing through additional service providers in route, decisions obviously cease to be individual service provider issues. In Europe, where multiple countries are involved as well to further complicate the situation, service providers wisely began working together in unions to develop operating standards.

E1 Telecom transport standards were an important outcome of these efforts. Essentially they represented an agreement on the digital packetizing of voice communication so that voice calls could easily transition between different service provider networks. This standardized transport is the bedrock of network interoperability and painless call routing.

E1 Telecom Geography and Architecture - E1 in Europe is very similar to T1 in the United States

Similar to the T-carrier structure of many networks in the United States, E-carrier systems have become a standard across the pond in Europe. E1 networks operate in such a way that allows for an abundance of voice conversations to be transmitted over a single circuit instead of needing a separate, dedicated circuit for each conversation.

Time-digital Multiplexing and Data Compression - How E1 encapsulates multiple voice conversations

Through the use of time-digital multiplexing, telecom companies utilizing an E1 connection have a series of time slots on a single channel. Digital packets of information from multiple calls can be sent to a receiver in one or more time slots.

Carefully designed data compression / expansion algorithms enable voice communication to be quite clear with no noticeable audio artifacts from the multiplexing or the compression / expansion.

E1 Standards Adoption - Many countries outside of the United States choose to use E1 as a Standard

The E1 standards have become rather common in almost all countries around the world except for countries with established T1 networks; most notably the United States., Canada, and Japan. Created by the Commission of European Post and Telecommunications (CEPT) and adopted by the International Telecommunication Union Telecommunication Standardization Sector (ITU-T), the E-carrier networks (most often E1), have become an international foundation for digital voice communications around the world.

Is E1 easier or harder to manage than other data transport channels?

As you know, any telecom system requires good remote monitoring and control to stay online consistently. If you don't know what's happening at your remote sites, you can't respond to small threats. HVAC failures site unnoticed for hours and become thermal shutdowns. Minor equipment hiccups eventually trigger service outages.

E1 is no exception. It must be remotely monitored. One challenge that is common with E1 (and its close cousin T1) is a lack of IP/LAN. Any site where E1 is the primary transport channel is probably a very remote outside-plant facility. Since most telecom equipment assumes the availability of LAN, providing it can be difficult at such a remote location. You used to need an expensive "LAN card" from your transport manufacturer. Now, fortunately, there are better options. Let's take a look at one of the better ones, which has been a clever and versatile innovation for telcos worldwide:

A new solution for monitoring and LAN mediation: An E1-native Remote Telemetry Unit

Recently, new developments in remote monitoring technology have made it much easier for you to work with outside-plant transport. Versions of this technology have been developed for T1, Fiber, and E1.

Its easy to install - here's how the system works:

  1. Choose an E1-native RTU with a built-in LAN switch.
  2. Connect the RTU to your central office via E1.
  3. Plug other LAN equipment at the remote site into the RTU's LAN switch, granting it access to your network that would otherwise be impossible.

As you can see, this single device is capable of performing multiple functions. It's a remote monitoring RTU, so it collects alarm data and can issue control commands at your facility. It's an E1-to-LAN mediator, so it can communicate back to your central office using the available transport. It's also an E1-to-LAN mediator to other devices via its onboard switch, so all of your other critical gear can access your network

This new development in monitoring technology has directly reduced your potential cost for deployment. Buying one box is always cheaper than buying three. Installing one box is always faster and cheaper than installing three. There's also a reduction operational expenses. A single integrated RTU will be supported by the manufacturer. If you try to piece together the same functions with multiple devices, there's no manual and no tech support. Most of the time, each of your vendors will end up blaming the others.

Where have E1-native Remote Telemetry Units been deployed?

T1 is the common standard in the United States, so RTUs that support E1 are deployed in other countries that have standardized on E1. The Philippines is home to one example, where the national power company has deployed NetGuardian 832A RTUs specially equipped to handle E1.

Applications Drawing for the NGCP DPS solutions
Although the first NetGuardian shipped to NGCP for testing was just a 125 VDC build of the 832A, the final design also featured E1-capable RTU's reporting back to a T/Mon master station via E1 WAN Muxes and VLAN Routers.

National Grid Corporation of the Philippines (NGCP) rolled out a system built from E1-equipped NetGuardian remotes, E1 WAN muxes, VLAN routers, and a T/Mon master station. This single system took over for a much more complicated assortment of disconnected systems. That kind of efficiency boost is a great help for protecting revenues and cutting costs (the two sides of your bottom-line profits). Full E1 case study...

Critical to their success in this project was working with a manufacturer ("DPS Telecom") who could develop a perfect-fit solution. This helped during all phases of the project:

  • Initial Planning:
    NGCP was able to explain general requirements to DPS. DPS then asked follow-up questions and created preliminary application diagrams. This helped to clarify the solution well before implementation.
  • Purchasing:
    Buying from a single vendor instead of several reduces complexity and confusion.
  • Deployment:
    As a single vendor, DPS was able to help coordinate the project rollout. Multiple vendors cannot be expected to understand (and respond to) a client's overall project needs. Multiple vendors simply don't have enough "skin in the game".
  • Ongoing Support:
    One vendor has one tech support line. The team understands the complete implementation, and "blaming it on the other guy" is impossible. There is no other guy.
Full NGCP E1 case study...


Similar Topics:
E1 Equipment.
E1 RTUs.
E-Carrier System History.