- introduction to mobile telecommunications and an overview of the GSM standard. - It introduces the main system components, the network structure and basic terminology used.. - Describe the history of GSM development. - Describe the philosophy of GSM as a global common standard. - Describe the GSM network components. - Describe the GSM geographical network structure. - Describe the GSM frequency bands. - HISTORY OF GSM. - MSC SERVICE AREA. - PLMN SERVICE AREA. - GSM SERVICE AREA. - Mobile telecommunications is one of the fastest growing and most demanding of all telecommunications technologies.. - In the future, cellular systems employing digital technology will become the universal method of telecommunication.. - The origins of mobile communications followed quickly behind the invention of radio in the late 1800s. - The major milestones in the development of wireless communications are summarized in the following table:. - 1921 The Detroit police department used a 2 MHz frequency in the department's first vehicular mobile radio. - 1930s Amplitude Modulation (AM) two-way mobile systems were in place in the U.S. - By the end of the decade channel. - This led to the standardization of telecommunications for all members of the Nordic Mobile Telephone (NMT) group, the first. - 1979 The FCC authorized the installation and testing of the first developmental cellular system in the US (Illinois Bell Telephone Company).. - For example, this includes specification of the following:. - Each mobile standard has been developed to meet the particular requirements of the country or interest groups. - The main standards and the main markets in which they are used are summarized in the following table.. - Ericsson is one of the leading telecommunication companies in the world, with customers in more than 130 countries. - Ericsson’s key product is the AXE digital exchange which is in service in the most sophisticated public networks in Europe, the Americas, Australia, Africa and Asia. - One of the key reasons for the success of AXE is that it is modular in design which allows it to adapt easily to a wide variety of applications. - Ericsson is the world's most successful supplier of mobile network infrastructure equipment and supplies 40% of the world's mobile telephony market. - Ericsson supplies 50% of the world's digital telephony market. - This history of GSM is outlined in the following table:. - standard in the 900 MHz frequency band. - 1991 • The GSM 1800 standard was released.. - The number of GSM subscribers reached one million.. - The first commercial DCS 1800 system was launched in the U.K.. - 1994 • The MoU now had over 100 signatories covering 60 countries.. - The total number of GSM subscribers exceeded 3 million.. - 1995 • The specification for the Personal Communications Services (PCS) was. - developed in the U.S.A. - This version of GSM operates at 1900 MHz.. - GSM growth trends continued steadily through 1995, with the number of GSM subscribers increasing at the rate of 10,000 per day and rising.. - In April 1995, there were 188 members of the MoU from 69 countries.. - 1996 • The first GSM 1900 systems became available.. - of the world’s mobile market.. - Because GSM provides a common standard, cellular subscribers can use their telephones over the entire GSM service area which includes all the countries around the world where the GSM system is used.. - The GSM specifications do not specify the actual hardware requirements, but instead specify the network functions and interfaces in detail. - The GSM recommendations consist of twelve series which are listed in the table below These series were written by different working parties and a number of expert groups. - A permanent nucleus was established in order to coordinate the working parties and to manage the editing of the recommendations. - In the late 1980s, the groups involved in developing the GSM standard realized that within the given time-frame they could not complete the specifications for the entire range of GSM services and features as originally planned. - Some of the enhancements offered by Phase 2+ include:. - The GSM network is divided into two systems. - Each of these systems are comprised of a number of functional units which are individual components of the mobile network. - The BSS is comprised of the following functional units:. - The OMC performs all the operation and maintenance tasks for the network such as monitoring network traffic and network alarms. - network’s HLR in order to route a call to a Mobile Station (MS).. - Any MSC in the mobile network can function as a gateway by integration of the appropriate software.. - The VLR database contains information about all the mobile subscribers currently located in an MSC service area. - temporarily stores subscription information so that the MSC can service all the subscribers currently visiting that MSC service area. - The VLR can be regarded as a distributed HLR as it holds a copy of the HLR information stored about the subscriber.. - The HLR sends a copy of the information to the VLR and updates its own location. - The main function of the AUC is to authenticate the subscribers attempting to use a network. - The BSC manages all the radio-related functions of a GSM network. - The BTS controls the radio interface to the MS. - comprises the radio equipment such as transceivers and antennas which are needed to serve each cell in the network. - In the OMC, staff are presented with information about the status of the network and can monitor and control a variety of system parameters. - There may be one or several OMCs within a network depending on the network size.. - The range or coverage area of an MS depends on the output power of the MS. - The identity of the LA in which an MS is currently located is stored in the VLR.. - An MSC service area is made up of a number of LAs and represents the geographical part of the network controlled by one MSC. - In order to be able to route a call to an MS, the subscriber’s MSC service area is also recorded and monitored.. - The subscriber’s MSC service area is stored in the HLR.. - Figure 1-6 MSC service area. - A Public Land Mobile Network (PLMN) service area is the entire set of cells served by one network operator and is defined as the area in which an operator offers radio coverage and access to its network. - The GSM service area is the entire geographical area in which a subscriber can gain access to a GSM network. - The GSM service area increases as more operators sign contracts agreeing to work together. - Currently, the GSM service area spans dozens of countries across the world from Ireland to Australia and South Africa.. - The figures below show alternative views of the same network:. - The first figure shows the network nodes and their layout across the network. - For simplicity, this may be referred to as the hardware view of the network.. - For simplicity, this may be referred to as the software view of the network.. - MSC/VLR 2 MSC Service Area 1 MSC Service Area 2. - Cell 2-A-25 MSC Service Area 2. - MSC Service Area 1. - countries and extended version of GSM 900 can be used, which provides extra network capacity. - This extended version of GSM is called E-GSM, while the primary version is called P-GSM.. - GSM 1800. - In 1990, in order to increase competition between operators, the United Kingdom requested the start of a new version of GSM adapted to the 1800 MHz frequency band. - In 1995, the Personal Communications Services (PCS) concept was specified in the United States. - An MS can have one of the following states:. - ,GOH the MS is ON but a call is not in progress. - $FWLYH the MS is ON and a call is in progress. - 'HWDFKHG the MS is OFF. - An MS roaming around the network must inform the network when it enters a new LA. - When an MS is powered off it is detached from the network.. - When the subscriber switches power on, the MS scans the GSM frequencies for special channels called control channels. - When it finds a control channel, the MS measures the signal strength it receives on that channel and records it. - channels have been measured, the MS tunes to the strongest one.. - When the MS has just been powered on, the MS must register with the network which will then update the MS’s status to idle.. - If the location of the MS is noticed to be different from the currently stored location then a location update will also take place.. - As the MS moves through the network, it continues to scan the control channels to ensure that it is tuned to the strongest. - If the MS finds one which is stronger, then the MS retunes to this new control channel 2 . - If the new control channel belongs to a new LA, the MS will also inform the network of its new location.
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