Wednesday, February 23, 2011

Understand about 2G - much talked these days!!!

Understand about 2G

Thanks to some of our shrewd and crooked politicians, make more technological knowhow, even to a layman through their well organized and simpler way of minting and siphoning cores of money!! India has unique record of not sending a single political person behind bars after successful court judgment. This could be also a similar one though it is termed as sensational one. Human memory is short and this is well understood by all politician and make merry!!!

One such latest one talked by one and all is 2G spectrum scam. I try to understand on this scam as well as what is that 2G itself!!

I am sharing with others too for better understanding on this subject.    

What is 2G spectrum scam?
(As read at NDTV)

The 2G spectrum scam involved officials and ministers in the Government of India illegally undercharging mobile telephony companies for frequency allocation licenses, which they would use to create 2G subscriptions for cell phones. According to a report submitted by the Comptroller and Auditor General based on money collected from 3G licenses, the loss to the exchequer was Indian Rupee ₹176,379 crore (US$38.27 billion). The issuing of the 2G licenses occurred in 2008, but the scam came to public notice when the Indian Income Tax Department investigated political lobbyist Niira Radia and the Supreme Court of India took Subramaniam Swamy's complaints on record [With Case type: Writ Petition (Civil),Case No:10, Year:2011].The case details of the main PIL filed with the supreme court is Type: Writ Petition (Civil),Case No:423, Year:2010
In 2008, the Income Tax department, after orders from the ministry of Home and the PMO, began tapping the phones of Niira Radia. This was done to help with an ongoing investigation 
into a case where it was alleged that Niira Radia had acted as a spy.

Some of the many conversations recorded over 300 days were leaked to the media. The intense controversy around the leaked tapes, became known in the media as the Radia tapes controversy. The tapes featured some explosive conversations between Politicians, Journalists and Corporate Houses. Politicians from Karunanidhi to Arun Jaitley, journalists like Barkha Dutt and Vir Sanghvi and Industrial groups like the Tata's were either participants or mentioned in these explosive tapes.

  • 2G licenses issued to private telecom players at throwaway prices in 2008
  • CAG: Spectrum scam has cost the government Rs. 1.76 lakh crore
  • CAG: Rules and procedures flouted while issuing licenses
  •  Entry fee for spectrum licenses in 2008 pegged at 2001 prices
  •  Mobile subscriber base had shot up to 350 million in 2008 from 4 million in 2001
  • Rules changed after the game had begun
  • Cut-off date for applications advanced by a week
  • Licenses issued on a first-come-first-served basis
  • No proper auction process followed, no bids invited
  • Raja ignored advice of TRAI, Law Ministry, Finance Ministry
  • TRAI had recommended auctioning of spectrum at market rates
  • Unitech, Swan Telecom got licenses without any prior telecom experience
  • Swan Telecom given license even though it did not meet eligibility criteria
  • Swan got license for Rs. 1537 crore, sold 45% stake to Etisalat for Rs. 4200 crore
  • Unitech Wireless got license for Rs. 1661 crore, sold 60% stake for Rs. 6200 crore
  • All nine companies paid DoT only Rs. 10,772 crore for 2G licences

What is 2G?

Before going into this, some background to understand better on this mobile telephone.

Mobile radio telephone

These early mobile telephone systems can be distinguished from earlier closed radiotelephone systems in that they were available as a commercial service that was part of the public switched telephone network, with their own telephone numbers, rather than part of a closed network such as a police radio or taxi dispatch system.
These mobile telephones were usually mounted in cars or trucks, though briefcase models were also made. Typically, the transceiver (transmitter-receiver) was mounted in the vehicle 
trunk and attached to the "head" (dial, display, and handset) mounted near the driver seat.


1G (or 1-G) refers to the first-generation of wireless telephone technology, mobile telecommunications. These are the analog telecommunications standards that were introduced in the 1980s and continued until being replaced by 2G digital telecommunications. The main difference between two succeeding mobile telephone systems, 1G and 2G, is that the radio signals that 1G networks use are analog, while 2G networks are digital.

Although both systems use digital signaling to connect the radio towers (which listen to the handsets) to the rest of the telephone system, the voice itself during a call is encoded to digital signals in 2G whereas 1G is only modulated to higher frequency, typically 150 MHz and up.

2G (or 2-G) is short for second-generation wireless telephone technology. Second generation 2G cellular telecom networks were commercially launched on the GSM standard in Finland by Radiolinja (now part of Elisa Oyj) in 1991. Three primary benefits of 2G networks over their predecessors were that phone conversations were digitally encrypted; 2G systems were significantly more efficient on the spectrum allowing for far greater mobile phone penetration levels; and 2G introduced data services for mobile, starting with SMS text messages.

After 2G was launched, the previous mobile telephone systems were retrospectively dubbed 1G. While radio signals on 1G networks are analog, radio signals on 2G networks are digital. Both systems use digital signaling to connect the radio towers (which listen to the handsets) to the rest of the telephone system.

2G has been superseded by newer technologies such as 2.5G, 2.75G, 3G, and 4G; however, 2G networks are still used in many parts of the world.

2G technologies

2G technologies can be divided into TDMA-based and CDMA-based standards depending on the type of multiplexing used. The main 2G standards are:
  • GSM (TDMA-based), originally from Europe but used in almost all countries on all six inhabited continents. Today accounts for over 80% of all subscribers around the world. Over 60 GSM operators are also using CDMA2000 in the 450 MHz frequency band (CDMA450]
  • IS-95 aka cdmaOne (CDMA-based, commonly referred as simply CDMA in the US), used in the Americas and parts of Asia. Today accounts for about 17% of all subscribers globally. Over a dozen CDMA operators have migrated to GSM including operators in Mexico, India, Australia and South Korea.
  • PDC (TDMA-based), used exclusively in Japan
  • iDEN (TDMA-based), proprietary network used by Nextel in the United States and Telus Mobility in Canada
  • IS-136 aka D-AMPS (TDMA-based, commonly referred as simply 'TDMA' in the US), was once prevalent in the Americas but most have migrated to GSM.
2G services are frequently referred as Personal Communications Service, or PCS, in the United States.

Capacities, advantages, and disadvantages

Using digital signals between the handsets and the towers increases system capacity in two key ways:
  • Digital voice data can be compressed and multiplexed much more effectively than analog voice encodings through the use of various codecs, allowing more calls to be packed into the same amount of radio bandwidth.
  • The digital systems were designed to emit less radio power from the handsets. This meant that cells could be smaller, so more cells could be placed in the same amount of space. This was also made possible by cell towers and related equipment getting less expensive.
  • The lower power emissions helped address health concerns.
  • Going all-digital allowed for the introduction of digital data services, such as SMS and email.
  • Greatly reduced fraud. With analog systems it was possible to have two or more "cloned" handsets that had the same phone number.
  • Enhanced privacy. A key digital advantage not often mentioned is that digital cellular calls are much harder to eavesdrop on by use of radio scanners. While the security algorithms used have proved not to be as secure as initially advertised, 2G phones are immensely more private than 1G phones, which have no protection against eavesdropping.
  • In less populous areas, the weaker digital signal may not be sufficient to reach a cell tower. This tends to be a particular problem on 2G systems deployed on higher frequencies, but is mostly not a problem on 2G systems deployed on lower frequencies. National regulations differ greatly among countries which dictate where 2G can be deployed.
  • Analog has a smooth decay curve, digital a jagged steppy one. This can be both an advantage and a disadvantage. Under good conditions, digital will sound better. Under slightly worse conditions, analog will experience static, while digital has occasional dropouts. As conditions worsen, though, digital will start to completely fail, by dropping calls or being unintelligible, while analog slowly gets worse, generally holding a call longer and allowing at least a few words to get through.
  • While digital calls tend to be free of static and background noise, the lossy compression used by the codecs takes a toll; the range of sound that they convey is reduced. You'll hear less of the tonality of someone's voice talking on a digital cellphone, but you will hear it more clearly.
2G networks were built mainly for voice services and slow data transmission.
Some protocols, such as EDGE for GSM and 1x-RTT for CDMA2000, are defined as "3G" services (because they are defined in IMT-2000 specification documents), but are considered by the general public to be 2.5G services (or 2.75G which sounds even more sophisticated) because they are several times slower than present-day 3G services.
2.5G (GPRS)

2.5G is a stepping stone between 2G and 3G cellular wireless technologies. The term "second and a half generation   is used to describe 2G-systems that have implemented a packet switched domain in addition to the circuit switched domain. It does not necessarily provide faster services because bundling of timeslots is used for circuit switched data services (HSCSD) as well.

The first major step in the evolution of GSM networks to 3G occurred with the introduction of General Packet Radio Service (GPRS). CDMA2000 networks similarly evolved through the introduction of 1xRTT. The combination of these capabilities came to be known as 2.5G.

GPRS could provide data rates from 56 kbit/s up to 115 kbit/s. It can be used for services such as Wireless Application Protocol (WAP) access, Multimedia Messaging Service (MMS), and for Internet communication services such as email and World Wide Web access. GPRS data transfer is typically charged per megabyte of traffic transferred, while data communication via traditional circuit switching is billed per minute of connection time, independent of whether the user actually is utilizing the capacity or is in an idle state.
1xRTT supports bi-directional (up and downlink) peak data rates up to 153.6 kbit/s, delivering an average user data throughput of 80-100 kbit/s in commercial networks It can also be used for WAP, SMS & MMS services, as well as Internet access.

2.75G (EDGE)
GPRS networks evolved to EDGE networks with the introduction of 8PSK encoding. Enhanced Data rates for GSM Evolution (EDGE), Enhanced GPRS (EGPRS), or IMT Single Carrier (IMT-SC) is a backward-compatible digital mobile phone technology that allows improved data transmission rates, as an extension on top of standard GSM. EDGE was deployed on GSM networks beginning in 2003—initially by Cingular (now AT&T) in the United States.

EDGE is standardized by 3GPP as part of the GSM family and it is an upgrade that provides a potential three-fold increase in capacity of GSM/GPRS networks. The specification achieves higher data-rates (up to 236.8 kbit/s) by switching to more sophisticated methods of coding (8PSK), within existing GSM time slots.

Further we have 3G,4G, 5G phones. This is the out come of constant technological advancement and research.

1 comment:

kaykay said...

Very good info ...systematically compiled.