HISTORY
Early European analog cellular networks employed an uncoordinated mix of technologies and protocols that varied from country to country, preventing interoperability of subscriber equipment and increasing complexity for equipment manufacturers who had to contend with varying standards from a fragmented market. The work to develop a European standard for digital cellular voice telephony began in 1982 when the European Conference of Postal and Telecommunications Administrations (CEPT) created the Groupe Spécial Mobile committee and provided a permanent group of technical support personnel, based in Paris. In 1987, 15 representatives from 13 European countries signed a memorandum of understanding to develop and deploy a common cellular telephone system across Europe. The foresight of deciding to develop a continental standard paid off, eventually resulting in a unified, open, standard-based network larger than that in the United States.
France and Germany signed a joint development agreement in 1984 and were joined by Italy and the UK in 1986. In 1986 the European Commission proposed to reserve the 900 MHz spectrum band for GSM. By 1987, the basic parameters of the GSM standard had been agreed upon and 15 representatives from 13 European nations signed a memorandum of understanding in Copenhagen, committing to deploy GSM. In 1989, the Groupe Spécial Mobile Committee was transferred from CEPT to the European Telecommunications Standards Institute (ETSI).
Phase I of the GSM specifications were published in 1990. The historic world’s first GSM call was made by the Finnish Prime Minister, Harri Holkeri to Kaarina Suonio, Mayor of the city of Tampere) on July 1, 1991. The first network was built by Telenokia and Siemens and operated by Radiolinja.
In 1992, the first short messaging service (SMS or “text message”) message was sent and Vodafone UK and Telecom Finland signed the first international roaming agreement. Work had begun in 1991 to expand the GSM standard to the 1800 MHz frequency band and the first 1800 MHz network became operational in the UK in 1993.
Also in 1993, Telecom Australia became the first network operator to deploy a GSM network outside of Europe and the first practical hand-held GSM mobile phone became available. In 1995, fax, data, and SMS messaging services became commercially operational, the first 1900 MHz GSM network in the world became operational in the United States and GSM subscribers worldwide exceeded 10 million. In this same year, the GSM Association was formed. Pre-paid GSM SIM cards were launched in 1996 and worldwide GSM subscribers passed 100 million in 1998.
In 2000, the first commercial GPRS services were launched and the first GPRS-compatible handsets became available for sale. In 2001 the first UMTS (W-CDMA) network was launched and worldwide GSM subscribers exceeded 500 million. In 2002 the first multimedia messaging services (MMS) were introduced and the first GSM network in the 800 MHz frequency band became operational. EDGE services first became operational in a network in 2003 and the number of worldwide GSM subscribers exceeded 1 billion in 2004.
By 2005, GSM networks accounted for more than 75% of the worldwide cellular network market, serving 1.5 billion subscribers. In 2005, the first HSDPA-capable network also became operational. The first HSUPA network was launched in 2007 and worldwide GSM subscribers exceeded two billion in 2008.
The GSM Association estimates that technologies defined in the GSM standard serve 80% of the global mobile market, encompassing more than 1.5 billion people across more than 212 countries and territories, making GSM the most ubiquitous of the many standards for cellular networks.
Technical details
GSM is a cellular network, which means that mobile phones connect to it by searching for cells in the immediate vicinity. There are five different cell sizes in a GSM network—macro, micro, pico, femto, and umbrella cells. The coverage area of each cell varies according to the implementation environment. Macro cells can be regarded as cells where the base station antenna is installed on a mast or a building above average rooftop level. Micro cells are cells whose antenna height is under average rooftop level; they are typically used in urban areas. Picocells are small cells whose coverage diameter is a few dozen metres; they are mainly used indoors. Femtocells are cells designed for use in residential or small business environments and connect to the service provider’s network via a broadband internet connection. Umbrella cells are used to cover shadowed regions of smaller cells and fill in gaps in coverage between those cells.
Cell horizontal radius varies depending on antenna height, antenna gain, and propagation conditions from a couple of hundred meters to several tens of kilometres. The longest distance the GSM specification supports in practical use is 35 kilometres (22 mi). There are also several implementations of the concept of an extended cell, where the cell radius could be doubled or even more, depending on the antenna system, the type of terrain, and the timing advance.
Indoor coverage is also supported by GSM and may be achieved by using an indoor picocell base station, or an indoor repeater with distributed indoor antennas fed through power splitters, to deliver the radio signals from an antenna outdoors to the separate indoor distributed antenna system. These are typically deployed when a lot of call capacity is needed indoors; for example, in shopping centers or airports. However, this is not a prerequisite, since indoor coverage is also provided by in-building penetration of the radio signals from any nearby cell.
The modulation used in GSM is Gaussian minimum-shift keying (GMSK), a kind of continuous-phase frequency shift keying. In GMSK, the signal to be modulated onto the carrier is first smoothened with a Gaussian low-pass filter before being fed to a frequency modulator, which greatly reduces the interference to neighboring channels (adjacent-channel interference).
GSM carrier frequencies
GSM networks operate in several different carrier frequency ranges (separated into GSM frequency ranges for 2G and UMTS frequency bands for 3G), with most 2G GSM networks operating in the 900 MHz or 1800 MHz bands. Where these bands were already allocated, the 850 MHz and 1900 MHz bands were used instead (for example in Canada and the United States). In rare cases, the 400 and 450 MHz frequency bands are assigned in some countries because they were previously used for first-generation systems.
Most 3G networks in Europe operate in the 2100 MHz frequency band.
Regardless of the frequency selected by an operator, it is divided into timeslots for individual phones to use. This allows eight full-rate or sixteen half-rate speech channels per radio frequency. These eight radio timeslots (or eight burst periods) are grouped into a TDMA frame. Half-rate channels use alternate frames in the same timeslot. The channel data rate for all 8 channels is 270.833 kbit/s, and the frame duration is 4.615 ms.
The transmission power in the handset is limited to a maximum of 2 watts in GSM850/900 and 1 watts in GSM1800/1900.
Subscriber Identity Module (SIM)
One of the key features of GSM is the Subscriber Identity Module, commonly known as a SIM card. The SIM is a detachable smart card containing the user’s subscription information and phone book. This allows the user to retain his or her information after switching handsets. Alternatively, the user can also change operators while retaining the handset simply by changing the SIM. Some operators will block this by allowing the phone to use only a single SIM or only a SIM issued by them; this practice is known as SIM locking.
SIM/Phone lock
Sometimes mobile network operators restrict handsets that they sell for use with their network. This is called locking and is implemented by a software feature of the phone. Because the purchase price of the mobile phone to the consumer is typically subsidized with revenue from subscriptions, operators must recoup this investment before a subscriber terminates service. A subscriber may usually contact the provider to remove the lock for a fee, utilize private services to remove the lock or make use of free or fee-based software and websites to unlock the handset themselves.
In some territories (e.g., Bangladesh, Hong Kong, India, Malaysia, Pakistan, and Singapore) all phones are sold unlocked. In others (e.g., Finland, Singapore) it is unlawful for operators to offer any form of subsidy on a phone’s price.[9]
GSM service security
GSM was designed with a moderate level of service security. The system was designed to authenticate the subscriber using a pre-shared key and challenge-response. Communications between the subscriber and the base station can be encrypted. The development of UMTS introduces an optional Universal Subscriber Identity Module (USIM), that uses a longer authentication key to give greater security, as well as mutually authenticating the network and the user – whereas GSM only authenticates the user to the network (and not vice versa). The security model, therefore, offers confidentiality and authentication, but limited authorization capabilities, and no non-repudiation.
GSM uses several cryptographic algorithms for security. The A5/1 and A5/2 stream ciphers are used for ensuring over-the-air voice privacy. A5/1 was developed first and is a stronger algorithm used within Europe and the United States; A5/2 is weaker and used in other countries. Serious weaknesses have been found in both algorithms: it is possible to break A5/2 in real-time with a ciphertext-only attack, and in February 2008, Pico Computing, Inc. revealed its ability and plans to commercialize FPGAs that allow A5/1 to be broken with a rainbow table attack. The system supports multiple algorithms so operators may replace that cipher with a stronger one.
On 28 December 2009, German computer engineer Karsten Nohl announced that he had cracked the A5/1 cipher. According to Nohl, he developed a number of rainbow tables (static values that reduce the time needed to carry out an attack) and has found new sources for known plaintext attacks. He also said that it is possible to build “a full GSM interceptor … from open source components” but that they had not done so because of legal concerns.
In January 2010, threatpost.com reported that researchers had developed a new attack that had “broken Kasumi” (also known as A5/3), the standard encryption algorithm used to secure traffic on 3G GSM wireless networks, by means of a sandwich attack (a type of related-key attack), allowing them to identify a full key. It reported experts as saying that this “is not the end of the world for Kasumi.” (Paper[14]) The researchers noted that their attack failed on its predecessor algorithm MISTY1, and observed that the GSM Association’s change of standard from MISTY to KASUMI resulted in a “much weaker cryptosystem”. This was followed between December 2010 and April 2011 by an announcement from other researchers that they had reverse-engineered the GSM encryption algorithms, and demonstrated software capable of real-time interception of GSM voice calls.
New attacks have been observed that take advantage of poor security implementations, architecture, and development for smartphone applications. Some wiretapping and eavesdropping techniques hijack the audio input and output providing an opportunity for a 3rd party to listen in to the conversation. At present such attacks often come in the form of a Trojan, malware, or a virus and might be detected by security software.
Culled from Wikipedia
Brief History of GSM & the GSMA
1982
Groupe Speciale Mobile (GSM) is formed by the Confederation of European Posts and Telecommunications (CEPT) to design a pan-European mobile technology.
1984
France & Germany sign a joint development agreement for GSM.
1985
‘GAP’ (Groupe d’Analyse et de Prevision’) meetings took place that led to the European Commission’s endorsement of the GSM project.
1986
EU Heads of State endorsed the GSM project. The European Commission initiative proposes to reserve the 900MHz spectrum band for GSM, as agreed in the EC Telecommunications Council.
A quadripartite agreement between France, Germany, Italy, and the UK cooperation agreement signed (to support the standards work and exchange research data).
Trials of different digital radio transmission schemes and different speech codecs in several countries, with comparative evaluation by CEPT GSM in Paris.
1987
Basic parameters of the GSM standard agreed in February.
Proposal agreed upon by four ministers from the quadripartite countries to create an Operator Agreement in the form of a ‘Memorandum of Understanding’. The ‘MoU’ was drawn up and signed in Copenhagen in September by 15 members from 13 countries that committed to deploying GSM.
1988
Completion of the first set of detailed GSM specifications for infrastructure tendering purposes.
Simultaneous issue of invitation to tender for networks by ten GSM network operators – all subsequently signed in the same year.
1989
Groupe Speciale Mobile (transferred to an ETSI technical committee) defines the GSM standard as the internationally accepted digital cellular telephony standard.
The UK’s Department of Trade & Industry (DTI) produced a document ‘Phones on the Move’ that first proposed PCN (Personal Communications Networks (later known as DCS 1800 and subsequently GSM 1800) networks to operate in the 1800 GHz frequency band.
1990
GSM adaptation work started for the DCS1800 band.
1991
The first GSM call was made by Radiolinja in Finland.
1992
First international roaming agreement signed between Telecom Finland and Vodafone (UK).
First SMS sent.
1993
Telstra Australia becomes the first non-European operator to sign the GSM MoU 32 networks on air in 18 countries or territories
First, truly hand-portable terminals are launched commercially. The world’s first DCS1800 (later GSM1800) network opened in the UK.
1994
GSM Phase 2 data/fax bearer services launched
GSM MoU membership surpasses 100 operators
GSM subscribers hit one million.
1995
GSM MoU group is formally registered as the GSM MoU Association in Switzerland with 117 networks on air.
Global GSM subscribers exceed 10 million.
GSM World Congress held in Madrid, Spain.
Formation of GSMA Regional Interest Groups (RIGs).
Fax, data, and SMS services started, and video over GSM was demonstrated.
The first North American PCS 1900 (now GSM 1900) network opened – via a phone call by US Vice President Al Gore.
1996
First GSM networks in Russia and China go live.
Pre-paid GSM SIM cards launched.
GSM MoU membership approaches 200 operators from nearly 100 countries.
167 networks live in 94 countries.
GSM World Congress moves to Cannes, France.
GSM subscribers hit 50 million.
GSMA Awards launched.
1997
15 GSM networks on air in the USA using the 1900MHz band.
100 countries on air globally
First tri-band handsets launched.
1998
Global GSM subscribers surpass 100 million.
1999
WAP trials begin in France and Italy.
Contracts placed for GPRS systems.
2000
First commercial GPRS services launched.
3G licence auctions commence.
First GPRS handsets enter the market.
Five billion SMS messages were sent in one month.
2001
The first 3GSM (W-CDMA) network goes live.
3GSM World Congress held in Cannes, France.
Fifty billion SMS messages were sent in the first three months.
GSM subscribers exceed 500 million.
First mobile phone colour screens launched
2002
GSM was introduced for the 800MHz band.
First Multimedia Messaging Services go live.
95% of nations worldwide have GSM networks.
400 billion SMS messages were sent in the year.
First mobile camera phones launched.
2003
First EDGE networks go live.
GSMA creates a new CEO-level Board.
Membership of the GSM Association breaks through the 200-country barrier.
Over half a billion handsets are produced in a year.
2004
GSM SURPASSES ONE BILLION CUSTOMERS.
More than 50 3GSM networks live.
GSM Association and Ovum announce market data venture: Wireless Intelligence.
2005
GSM surpasses 1.5 billion customers.
GSM dominates over 3/4 of the wireless market.
First HSDPA network goes live.
Over 100 3GSM networks launched.
120+ 3GSM handset models launched or announced.
The first ever sub-$30 mobile phone was announced.
Over one trillion SMS sent in the year
2006
GSM SURPASSES TWO BILLION CUSTOMERS.
Over 120 commercial 3GSM networks in more than 50 countries and almost 100 million subscriptions.
Approximately 85 HSDPA networks in the commercially launched by year-end.
66 HSDPA devices are available from 19 suppliers, including 32 handset models.
GSMA membership exceeds 900 companies (including over 700 operators).
Over 980 million handsets sold by year-end.
2007
Heading towards 2.5 billion GSM connections.
Further HSDPA network launches and introduction of HSUPA.
The first GSMA Mobile Asia Congress was held in Macau SAR, China.
GSMA celebrates its 20th anniversary.
2008
More than 55,000 visitors to the GSMA’s Mobile World Congress in Barcelona.
GSM surpasses 3 Billion connections
