Introduction
The development of GSM started in the 1980's. He was seen then as the cornerstone of plans for the mobile communications infrastructure in Europe for 1990. 1900 Today, GSM and DCS 1800 and PCS versions have been extended beyond Western Europe, with networks installed across all continents.
The story begins in 1982 when the European Conference of Postal and Telecommunications Administrations (CEPT), consisting then of the telecommunication authorities of 26 countries took two important decisions. The first was to create a team with the title "Special Mobile Group" (hence the term "GSM", which today means Global System for Mobile Communications) to develop a set of common rules for a future pan-European cellular network. The second was to recommend that two blocks of frequencies in the 900 MHz band be reserved for the system.
CEPT has taken these decisions in an attempt to solve the problems created by the uncoordinated development of various mobile communication systems using incompatible standards. Can not use the same terminal in different countries when traveling in Europe was one of these problems, another has been difficult to establish a pan-European mobile communications industry, which will compete global markets because of the lack of a sufficiently large domestic market with common standards - with its attendant economies of scale.
In 1986, it was clear that some of these analogue cellular networks would run out of capacity by early 1990. Accordingly, a directive has been issued for two blocks of frequencies in the 900 MHz band, but a little less than that recommended by the CEPT be strictly limited to a pan-European service to be opened in 1991.
Meanwhile, members of the GSM were making excellent progress with the development of agreed standards. An important decision was to accept a digital or analog.
The digital system would improve the efficiency of the spectrum, the provision of better quality and new services with advanced features, such as security. It would also be possible to use the Very Large Scale Integration (VLSI) technology, which would lead to smaller and cheaper phones, including handsets. In addition, the digital approach would complement the development of Integrated Services Digital Network (ISDN), which interfaces with the GSM.
GSM was originally for the Group Special Mobile, the CEPT (European Conference of Posts and Telegraphs) formed the group to develop a pan-European mobile to replace many existing systems in Europe have been inconsistent .
The main features of GSM were the ability to roam internationally, good sound quality, small, inexpensive mobile phones and the ability to handle large volumes of users. GSM was acquired in 1989 by ETSI (European Telecommunications Standards Institute) and closed the GSM standard in 1990. GSM service started in 1991. It has also been renamed this year for the global system for mobile communications (GSM).
Today there are approx. 105 countries with GSM networks, or planned and more are planned, with about 32 million subscribers worldwide in 139 networks. This represents over 25% of the cellular market in the world.
MOU Memorandum of Understanding "has over 210 members in 105 countries, the organization never meets three or four months to consider new or better implementations of the GSM system.
Highlights
1982 CEPT forms Group Special Mobile (GSM) and recommended the reservation of frequencies in the 900 MHz band for future pan-European mobile system.
1987 Memorandum of Understanding (MoU) was signed in Copenhagen, operators from thirteen countries in Europe.
1992 First commercial GSM network begins to spread.
1992 first agreement signed between Telecom Finland and Vodafone international roaming (UK) GSM networks.
1992, Australian operators are the first non-European operators to sign the Memorandum of Understanding.
Status Report 1993: Thirty GSM (end) service worldwide in more than one million customers. Seventy members of a Memorandum of Understanding of forty five countries.
1994 Status report: sixty GSM operation (end) worldwide, with over four million customers. Over a hundred members of the MoU than sixty countries.
1995 Progress Report: One hundred twenty (end) GSM networks in operation worldwide with more than twelve million customers. Over one hundred and fifty members MoU four countries.
Demands GSM
The voice quality of the GSM system must be better than that obtained by 900 MHz analog systems in all operating conditions.
The system provides user profile encryption
The system must operate in the frequency band 890-915MHz and 935-960MHz.
An international signaling standard is intended to allow the interconnection of mobile switching center and location registers.
Minimize changes to existing fixed public networks.
Design the system so that costs are minimized for all
Handset must be used in all participating countries
As flexibly as possible to other services such as ISDN
System must maximize the features and services to meet the special nature of mobile communications.
GSM Information
Quality
With digital photography, sound quality is crisp and clear. Background noise and static are reduced and cross-line conversations are also deleted. In comparison with analogue there are many fewer dropouts, and overall quality is closer to that of a landline.
Security
Unlike analog, everything you say and send in a digital network is secure. Some features are user authentication, which prohibits unauthorized access, distribution encryption key, which ensures the privacy restrictions of the call and caller ID, which can prevent the transmission of the call number of users to receiver.
Convenience Stores
With digital technology, the better, that's life better battery life. You have up to twice as much time talking about each battery charge, compared to analog. Moreover, digital service allows more calls to be handled at any time, thus reducing congestion in areas of dense population and high utilization.
Roaming
With digital, you can use the phone, and the number of countries around the world, operating a GSM network. Click here to see the list of GSM operators around the world. Or you can just take the SIM card and use another GSM phone. Home operator have a roaming agreement in force and shall be notified prior to departure, so you can activate in the country. All you have to do is connect your phone to the destination and automatically access the network. Depends on the country, you can still use the old SIM, but some countries require a SIM you get a loan provider before you go there. This will give you a new number, while in that country, but you can easily set up the introduction of a new number, if necessary.
GSM Phase 1 Features
Diversion
All calls
No response
Committed
Inaccessible
Call barring
Outgoing - Bars certain outgoing calls (eg, ISD)
Starters - Bar a few calls (useful if another country)
global roaming - Visit another country with GSM and a roaming agreement and use of your current phone number * (see section on homelessness)
GSM Phase 2 functions
SMS - Short Message Service - Allows you to send text messages too and from mobile
Multiparty Calling - Talk with other five parties, and even at the same time
Call Holding - Place a call on hold
Call Waiting - alerts you to another call during a call
Mobile data services - the handset can communicate with computers
Mobile Fax Service - Send the combined extract and receive faxes
Calling Line Identity Service - This service allows you to see the phone number of the incoming call on your phone before you answer
Notification of the load - can track call costs
Cell Broadcast - Subscribe to local news channels
Fax mobile termination - Another number that is issued with the receipt of faxes that can then go to the nearest fax machine.
GSM Phase 2 + features
Available in 1998
Upgrading and improvements to existing services
Most data on services including packet transmission upgrade bearer and data switching at 64 kbit / s and above
DECT access to GSM
capacity PMR / Public Access Mobile Radio (PAMR)-like
GSM loop
VPNs
Packet Radio
SIM improvements
premium rate services (eg stock prices on your phone)
96 GSM functions
In reality, there is no such thing as a 96 The GSM Memorandum of Understanding is a document called SE.03 Serg. In SE.03 find the date of implementation of services. And the date is "coded" if this is necessary at the beginning of the operation of the GSM network.
These services include: TS11 (speech based), TS12 (emergency calls/112), Call Forwarding SMS MT / call barring services and data / fax. Then run E96 servrvices service for roaming users by the end of 1996. The only service of this section is the phase of ODB 2. (Operator Determined ODB = exception).
E97 is a MO SMS (Short Message / mobile home).
List of E98 is longer. One reason is putting presure on the suppliers. Services included are CAMEL (support to the PNP input), ORS, USSD, HSCSD and GPRS.
The GSM network is composed of three parts, the mobile station (MS), which is similar to a cordless phone with additional features, Base Transceiver Station (BTS) that controls the connection to the Mobile Station, Base Station Controller (BSC) that controls multiply Base Transceiver Station and the rest of the network below ..
Mobile Station (MS)
A digital mobile phone and a SIM card is the mobile station. SIM (Subscriber Identity Module) card is a card that fits into your phone and is one of two formats - either full size (same size as a credit card) or the small plug in version. SIM microprocessor is based on a silicon chip that is designed to withstand temperatures from -25 degrees to +70 degrees Celsius, and will also resist the humidity is 85%. But silicon is fragile, and therefore, if the card is tampered with, physically or electronically, the card becomes unusable.
SIM contains all identification, such as IMSI (International Mobile Subscriber Identity. This is a numeric string, where the first three digits represent the country in which the SIM is from, the following is the actor in that country. The other numbers are entered the identity of the home network), phone memory, billing, SMS, PIN and information on international roaming.
The IMEI (International Mobile Equipment Identity) is the card serial number of the telephone set which is the equivalent number of NSE in an analog phone, the phone is fixed and can not be changed. The SIM card contains an IMSI (International Mobile Subscriber Identity), which identifies the user to the network computer and information security.
Base Station (RBS)
Base Transceiver Station consists of a radio transceiver with an antenna that covers a single cell. It manages communication with Member States through the radio interface.
BTS are linked together so you can move from one cell to another. The antenna can take various forms, in the United Kingdom lamps are used, but typically has three cells here.
Base Station Controller (BSC)
Base Station Controller manages multiple BTS. It controls the allocation and release of radio channels and transfers between cells.
A series of BTS is connected to each base station controller, the BSC keeps an eye on each call and decides when to switch the call to another BTS and which.
The rest of the network
Several CBS are controlled by the mobile switching center (MSC), MSC is working with four databases (HLR, VLR, EIR and AUC) and together they manage communications between mobile users and other networks. Each database has a separate work, these are
Mobile Switching Center (MSC)
Mobile Switching Center is the interface between the base system and the exchange of the subsystems of the cellular network. Moreover, MSC also has the interface with the cellular network and PSTN. MSC to produce billing information and ensure that any use is directed properly into account.
MSC is a rather complex task because, unlike traditional phone service, while GSM subscribers to call that could be anywhere on the web.
MSC must ensure that calls are routed through these customers, wherever they are and how they move throughout the duration of each cell. This situation becomes even more complex when two mobile subscribers need to contact each other from two distant places.
To simplify subscriber management function is a particular service area is allocated to each MSC. MSC has to manage change and the costs to customers in the service area, which includes coordination of all radio resources and activities inter-cell hand-off.
Location Register (HLR)
The HLR is the central database for all subscribers, which includes information on the identity of each subscriber, the services they have access and where the subscriber was last registered.
All procedures for the management of subscriptions reported HLR where the data is stored until it is the second part of the public land mobile network (PLMN).
The two key references that are used to route calls to each subscriber's international mobile subscriber identity (IMSI) and Mobile Subscriber Integrated Services Digital Network (MSISDN) number.
IMSI is a unique license number of the subscriber, which is stored in the SIM card and use the network for internal communications. If the SIM card is inserted into the phone, and becomes the mobile station.
The MSISDN is the number of mobile subscribers, which is attached to the IMSI in the HLR. Incoming calls to a subscriber, is translated back to the IMSI of CPR so that they can be delivered to the mobile station.
Once the MSISDN of the mobile station has been used to identify the IMSI, the HLR verifies the subscription records to ensure that the call can be sent to the last known position of the mobile station.
Visitor's Location Register (VLR)
The VLR is a database that is attached to an MSC and temporarily fixed information for each mobile workstation in the area served by the MSC.
Information temporarily stored in VLR is sufficient to allow a mobile station in the MSC area to make and receive calls. This includes the mobile station identity, the area where he was last registered and data relating to subscribers and any additional services that have been selected by the subscriber.
MSC always refers to the VLR, the mobile station attempts to ensure that the request can be fulfilled. This process has shown that barring any restrictions or guidelines are in place.
Equipment Identity Register (EIF)
The EIR will ensure that all mobile equipment are valid and authorized to operate in the PLMN. There are three categories in the EIR, a white list, a gray list and a blacklist.
A white list contains the IMEI number ranges of all movable property, which have been adopted in one of three centers of European GSM approval.
All mobile equipment, which is shown in gray in the list but shall act as an alarm is activated by the network operator. This arrangement allows the operator to identify any client who uses a stolen or lost mobile equipment.
Phones that are lost or stolen can be blacklisted, preventing them to work on national or PLMN PLMNs around the world.
Central Equipment Identity Register (CEIR)
An EIR is centrally administered by the Memorandum of Understanding of the Permanent Secretariat in Dublin, Ireland. Each member of the Memorandum of Understanding has agreed to connect its network to the EIR and CEIR in January 1995.
The advantage of having the concept CEIR is that it allows individual operators to restrict or prevent the application of a given MS across PLMNs, which are linked to CEIR.
Authentication Center (AUC)
The authentication center is used to validate the SIM card used by the mobile station. The secret information held in the CSA and also on the SIM card is used to perform complex mathematical calculations. initial authentication occurs if the results of these two calculations agree.
SMSC (SMS Service Center or center), SMSC addresses all SMS messages that are sent. Messages are sent to the station so you can get back on the call.
GMSC (Gateway MSC) is a gateway switch where the call is processed by the establishment of a call to a mobile phone user. The GMSC appears to the subscriber asking the right criteria HLR, VLR, so that queries and routes incoming calls to the MSC where the subscriber can be reached.
Conclusion
A truly international standard of GSM is critical to the success of the world. This has created a large market for mobile equipment and to promote competition among manufacturers of wide and lower prices for handsets and network equipment.
GSM also has all the characteristics of all GSM services and much more is added to both networks will be developed.
GSM has evolved to the point where it will be used in all countries (including Japan and the United States), making it easy homelessness and the ultimate in personal communication should be. Countries like the U.S. networks now based on GSM, but instead of 900MHz to 1800MHz and 1900 MHz works.
GSM GPRS
New GSM GPRS (General Packet Radio Services), data transmission has been optimized for "Burstyn" data services such as wireless Internet / intranet and multimedia services. It 'also known as GSM-IP (Internet Protocol) because it connects directly to the user's Internet service provider.
A major advantage of this new technology of packet switching is that users are always connected, always online, and can not be charged for the amount of data transported. Voice calls can be made simultaneously over GSM-IP while a data connection is running.
Users also benefit from easy and fast access to data from 114 kbps to various services.
Ericsson for example offers a robust IP end-to-end GPRS solution for open interfaces allow integration of multi-vendor networks.
The company's GPRS solution also provides advanced security for wireless use of intranet and corporate LAN services.
GPRS is a good add-on to integrate into existing networks. For new businesses, it is also attractive to launch GPRS networks to provide competitive services to Datacom.
Ericsson has already taken more than five contracts for a second technology for additional wireless services Datacom: HSCSD (High Speed Circuit Switched Data), which is particularly suitable for real time services and transfer large amounts of data such as video services.
Motorola GPRS solution introduces two new nodes in the GSM PLMN (Public Land Mobile Network) - The SGSN and GGSN.
Several new interfaces are added to connect the SGSN and GGSN appropriate GSM and GSM are not required to provide global packet data service.
Motorola's solution GPRS infrastructure is designed around a powerful IP routing engine, providing operators with a scalable and flexible solution that adapts the packet switching capability in line with subscriber growth expected data.
The SGSN tracks packages capable mobile sites, performs security functions and access control. The GGSN interfaces with external networks of packet data (PDN) to provide the routing destination for data to be delivered to the subscriber's mobile terminal and send data to the mobile home at destination.
The GGSN is connected to SGSN through a GPRS backbone network based on IP. The PCU performs radio functions and GPRS network functions. The PCU is connected to the OMC-G, base station controller and SGSN.
Previously, in 1999, Motorola and Cisco Systems Inc., the worldwide leader in networking for the Internet, today announced a strategic alliance to develop and deliver new global framework for Internet-based wireless networks. This collaboration will deliver the forum's first all-IP wireless industry that unites different standards for wireless services worldwide, and introduce an open platform for Internet-based integrated data, voice and video services over cellular networks.
