Basics of E1/T1 Link

Basics of E1/T1 Link or Data rate

E1:

It is the Basic Data rate of communication in telecommunication. It is the lowest level of the Plesiochronous Digital Hierarchy (PDH) and is among the most common ways of transmitting voice & data over telephone and data networks. Physically E1 is transmitted as 32 timeslots.

STANDARDS OF E 

E0=64 kbits/second
E1=2.048 kbits/s
E2=8.448 Mbits/s
E3=34.368 Mbits/s
E4=139.264 Mbits/s
E5=564.992 Mbits/s

E1 Link

• E1 link operates over two separate sets of wires. Usually Twisted pair cables.
• A nominal 3volt peak signal is encoded with pulses using a method that avoids long periods without polarity changes.
• This is an ideal for voice telephone calls where the voice is sampled.
• The line data rate of E1 is 2.048 Mbits/S. full duplex [2.048 Mbits/s upstream and downstream] which is split in to 32 time slots each being allocated 8 bits in turn.
• So each time slot sends and receives an 8bits/s of sample.
• 8000 times per second = 8* 8000* 32 = 2,048,000.
• The timeslots are numbered from 0-31.
• One timeslot ( TS0 ) is reserved for framing purposes and alternately transmits a fixed pattern.

TS0= Synchronization, Alarm transport, international carrier use.
E1 has 30 circuits.

One timeslot [ TS16] is often reserved for signalling purpose to control call setup and teardown according to telecommunication protocol.

This includes channel associating Signaling ( CAS ) where a set of bits is used opening and closing the ckt. where CAS is known as per trunk signaling , a form of digital communication.

PHYSICAL E1
Here two types of physical delivery option are available for E1:

• UNBALANCED [120w]: COPPER WIRE 4 [ One pair for TX ( 4+5) one pair for RX ( 1+2)
• BALANCED [75w]: COAX with BNC connector [one cable for RX and one cable for TX]

E1 Frame

The E1 framing is the first level in the digital hierarchy. The E1 frame carries 30 voice channels in a 256-bit frame. Since 30 channels only require 240 bits; 16 bits are available for framing, signaling, error checking and supervisory communications. These extra 16 bits are divided into two groups of 8 bits each.

E3 Frame

A group of E1 circuits bundled on to higher capacity E3 links between telephone exchanges or countries. This allows a network operator to provide a end-to-end E1 circuit between customers in different countries that share single high capacity links between them.

• E3 has 480 circuits.
• E3 has 512 timeslots and data rate as 34.368 Mbits/s.

-DR

Basics of PSTN

PSTN 

PUBLIC SWITCHED TELEPHONE NETWORK

PSTN is the global collection of interconnects originally designed to support circuit-switched voice communication. The PSTN provides the traditional Plain Old Telephone Service (POTS) to residences and many other establishments. Parts of the PSTN are also utilized for DSL, VoIP and other Internet-based network technologies.

The basic PSTN network link supports 64 Kbps bandwidth. In residences, the PSTN phone line caring this bandwidth is typically a copper cable. Traditional dial-up modems utilize nearly 56 Kbps of this bandwidth when connected to a phone line. The PSTN utilizes the SS7 signaling protocol.

Transfer of information in the PSTN takes place over land lined trunked lines consisting of fiber optic cables, copper cables, microwave link and satellite link. 

-DR

Basics of Radio (RF)

Radio frequency (RF) 

RF radiation is a subset of electromagnetic radiation with a wavelength of 100km to 1mm, which is a frequency of 3 KHz to 300 GHz, respectively.

This range of electromagnetic radiation constitutes the radio spectrum and corresponds to the frequency of alternating current electrical signals used to produce and detect radio waves.

RF can refer to electromagnetic oscillations in either electrical circuits or

radiation through air and space. Like other subsets of electromagnetic radiation, RF travels at the speed of light.

In order to receive radio signals, for instance from AM/FM radio stations, a radio antenna must be used. However, since the antenna will pick up thousands of radio signals at a time, a radio tuner is necessary to tune in to a particular frequency (or frequency range). This is typically done via a resonator (in its simplest form, a circuit with a capacitor and an inductor).

The resonator is configured to resonate at a particular frequency (or frequency band), thus amplifying sine waves at that radio frequency, while ignoring other sine waves. Usually, either the inductor or the capacitor of the resonator is adjustable, allowing the user to change the frequency at which it resonates.

Electrical currents that oscillate at RF have special properties not shared by direct current signals. One such property is the ease with which they can ionize air to create a conductive path through air.

This property is exploited by 'high frequency' units used in electric arc welding, although strictly speaking these machines do not typically employ frequencies within the HF band. Another special property is an electromagnetic force that drives the RF current to the surface of conductors, known as the skin effect.

Another property is the ability to appear to flow through paths that contain insulating material, like the dielectric insulator of a capacitor.

The degree of effect of these properties depends on the frequency of the signals.

-DR

Basics of SS7 or Signaling System 7

SS7- Signaling System 7:

It is an international telecommunication standard protocol used by mobile networks around the world.

SS7 is a protocol is widely used for common channel signaling between interconnected networks.

SS7 is used to interconnect most of the cellular MSCs .And is the key factor in enabling autonomous registration and automated roaming in first generation cellular systems.

Network Services part provides ISDN nodes with highly reliable and efficient means of exchanging signaling traffic using connection less services. 

The Signaling connection control part [SCCP] in ss7 actually supports packet data network interconnections as well as connection-oriented networking to virtual circuit networks.

The SS7 was the foundation for signaling for 2G and 3G circuit switch Network.

-DR

Basics of Mobile Backhaul

Mobile Backhaul

In a Telecommunication network the backhaul portion of the network comprises the intermediate links between the core network or backbone of the network and the small subnetworks at the edge of the entire hierarchical network.

like MSC-BSC-MSC or MSC-BSC-BTS-BSC-MSC

Examples:

• Connecting wireless base stations to the corresponding base station controllers.
• Connecting DSLAMS to nearest ATM or ethernet aggregation controllers.
• Connecting a large company's site to a metro ethernet network.

CORE NETWORK

A core network is a central part of telecom network that provides various services to customers who are connected by the access network.

Functionality of CORE NETWORK:-

1.Aggregation
2.Authentication
3.Call control/switching
4.Charging
5.Service Invocation
6.Gateways

-DR

Life from 1G to 4G

Mobile Connectivity 1G to 4G at a Glance

1G- 1st Generation Mobile/ wireless Communication 

Speed approx 2.4Kbps

2G- 2nd Generation Mobile/wireless Communication

Speed approx 1.3 Mbps

3G- 3rd Generation Mobile/wireless Communication

Speed approx 2 Mbps

Coming 4G- 4th Generation Mobile/wireless Communication

Speed approx 100 mbps- 1 Gbps

4th Generation

As we all are presently in 3G communication, we have crossed the 1G and 2G phase which have given the path to get more speed in coming technology. Now the very future is coming for 4th generation with more speed.

The WWRF (Wireless World Research Forum) defines 4G as a network that operates on Internet technology, combines it with other applications and technologies such as Wi-Fi and WiMAX, and runs at speeds ranging from 100 Mbps (in cell-phone networks) to 1 Gbits (in local Wi-Fi networks). 

4G is not just one defined technology or standard, but rather a collection of technologies and protocols to enable the highest throughput, lowest cost wireless network possible. The official designation from the IEEE for 4G is Beyond 3G. 

Some of the standards which pave the way for 4G systems are WiMAX, WiBro, and the proposed 3GPP Long Term Evolution work-in-progress technologies such as HSOPA. 4G is tower less wireless, more formally known as wireless ad hoc peer-to-peer networking. New data services, interactive TV and evolving Internet behavior will influence mobile data usage. Long sessions in always-on mode will force a re-think of radio access technology to achieve the required – but not easy to attain – capacity (Gbit/s/km) at low cost. 

Many technologies are competing on the road to 4G, Three paths are possible, even if they are more or less specialized. The first is the 3G-centric path, in which Code Division Multiple Access (CDMA) will be progressively pushed to the point at which terminal manufacturers will give up. When this point is reached, another technology will be needed to realize the required increases in capacity and data rates.. The second path is the radio LAN one. Widespread deployment of Wi-Fi for PCs, laptops and PDAs. In enterprises, voice may start to be carried by Voice over Wireless LAN (VoWLAN). However, it is not clear what the next successful technology will be. Reaching a consensus on a 200 Mbit/s (and more) technology will be a lengthy task, with too many proprietary solutions on offer.

A third path is IEEE 802.16e and 802.20, which are simpler than 3G for the equivalent performance. A core network evolution towards a broadband Next Generation Network (NGN) will facilitate the introduction of new access network technologies through standard access gateways, based on ETSI-TISPAN, ITU-T, 3GPP, China Communication Standards Association (CCSA) and other standards. How can an operator provide a large number of users with high session data rates using its existing infrastructure? 

The first (called “parent coverage”) is dedicated to large coverage and real-time services. Legacy technologies, such as 2G/3G and their evolutions will be complemented by Wi-Fi and WiMAX.

4G Features:

Multimedia, HD Voice, HD Video and other broadband internet services.

High speed internet with low cost.

And here comes 5G....Future Ahead..

Basics of ISDN

ISDN

Integrated Services Digital Network 

• ISDN is a set of communication standard for digital transmission of voice ,data ,video and other network services over traditional circuits of PSTN [public Switched telephone Network] . 
•  ISDN provides a complete digital interface between end-users over twisted pair telephone lines. 
•  ISDN provides two distinct kinds of signaling components to end-users in a telecommunication network, 1st one supports traffic between end-user and network [Access signaling] and 2nd is Network signaling and is governed by SS7 suite of protocols.
• ISDN is a circuit switched telephone network system, that also provides access to packet switched networks and is designed to allow digital transmission of voice and data over ordinary telephone copper wires, which enhances better voice quality.

Benefits:

• Carries a variety of user traffic signals, including data, voice, and video.
• Offers much faster call setup than modem connections.
• The Channel A provides 4khz analogue signal. 
• B channels provide a faster data transfer rate than modems.
• B channels are suitable for negotiated Point-to-Point Protocol (PPP) links which provides a 64kbps digital channel.
• ISDN also provides more bandwidth than a traditional 56 kbps dialup connection.
• ISDN uses bearer channels, also called B channels, as clear data paths. 
• Channel H was designed as a digital channel of 384, 1,536 or 1,920 kbps that provides the user with an information transfer capability.

As per some news media, it is considered that ISDN service may be stopped from year 2020. 

-DR