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Global system for mobile communication pdf

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GSM- Global System for Mobile Communication Hi Dear Readers! In this revision of the document, new data has been added with white color of words and black. GLOBAL SYSTEM FOR MOBILE COMMUNICATION. The GSM is Tideland Signal's unique approach to creating real time remote monitoring via a simple text. The Global System for Mobile Communication: The Hidden Wireless Networks and Mobile Communication, Standards .. Retrieved from: ayofoto.info ITU-D/Statistics/Documents/facts/ICTFactsFigurespdf.


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GSM Technology. Global System for Mobile Communication or. Groupe Special Mobile. To standardize cellular communication thoughout. Europe. Prior to it's. Global System for Mobile Communications (GSM). ✓ A set of recommendations and specifications for a digital cellular telephone network. (known as a Public. Global system for mobile communication (GSM) is a globally accepted standard for digital cellular communication. GSM is the name of a standardization group.

TDMA is a technique in which several different calls may share the same carrier. Dedicated channels are assigned to a mobile station, while common channels are used by idle mobile stations. The restriction service enables the calling party to restrict the presentation. This allows the system operator to purchase switching equipment from one supplier and radio equipment and the controller from another. The MS may include provisions for data communication as well as voice. To minimize co-channel interference and to conserve power, both the mobiles and the Base Transceiver Stations operate at the lowest power level that will maintain an acceptable signal quality.

The IMEI can be used to identify mobile units that are reported stolen or operating incorrectly. Just as the IMEI identities the mobile equipment, other numbers are used to identity the mobile subscriber.

Different subscriber identities are used in different phases of call setup. It is used by the land network to route calls toward an appropriate MSC. The international mobile subscribe identity IMSI is the primary function of the subscriber within the mobile network and is permanently assigned to him. The subscriber is identified in the system when he inserts the SIM card in the mobile equipment. This provides an enormous amount of flexibility to the subscribers since they can now use any GSM-specified mobile equipment.

The subscriber inserts it in the MS unit when he or she wants to use the MS to make or receive a call. The service provider if requested by the subscriber can also permanently bypass the PIN. According to the power and applications of it, M.

Their maximum allowed output power is 8 W. These terminals can emit up to 2 W of power. With evolution in technology, the maximum allowed power is reduced to 0. It is used in the case of system-internal signaling transactions in order to identify a subscriber. It is assigned only after successful subscriber authentication. Under certain condition Engr.

Here too the first two digits of the SN identify the HLR where the mobile subscriber is administrated. It is assigned upon demand by the HLR on a per-call basis. In conjunction with the IMSI, it is used to ensure that only authorized users are granted access to the system. The BS has a modular design and includes the: An interface is the entity responsible for communicating with MSs in a certain area.

The radio equipment of a BSS may be composed of one or more cells. The base station subsystem BSS is the section of a traditional cellular telephone network which is responsible for handling traffic and signaling between Engr. The BSS carries out transcoding of speech channels, allocation of radio channels to mobile phones, paging, quality management of transmission and reception over the air interface and many other tasks related to the radio network.

Detailed BSS Components 5. It is a functional entity that handles common control functions within a BTS. BSC within a mobile network is a key component for handling and routing information. It is a high-capacity switch that provides functions such as handover, cell configuration data, and control of radio frequency RF Engr.

It assigns and releases frequencies and timeslots for all MSs in its own area. It also reallocates frequencies to the BTSs in its area to meet locally heavy demands during peak hours or on special events. The minimum power level for a mobile unit is broadcast over the BCCH.

Redundancy often extends beyond the BSC equipment itself and is commonly used in the power supplies and in the transmission equipment providing the A-ter interface to PCU.

The databases for all the sites, including information such as carrier frequencies, frequency hopping lists, power reduction levels, receiving levels for cell border calculation, are stored in the BSC.

This data is obtained directly from radio planning engineering which involves modeling of the signal propagation as well as traffic projections. It performs some of the processing tasks of the BSC, but for packet data. The allocation of channels between voice and data is controlled by the base station, but once a channel is allocated to the PCU, the PCU takes full control over that channel.

The BTS is the radio equipment transceivers and antennas needed to service each cell in the network. BTS is typically able to handle three to five radio carries, carrying between 24 and 40 simultaneous communication. Reducing the BTS volume is important to keeping down the cost of the cell sites. BTS with its antennae [] A BTS compares radio transmission and reception devices, up to and including the antennas, and also all the signal processing specific to the radio interface. There are two categorize in which, BTS may be arranged in the cells depending upon the circumstances of the region in which they are to be used.

The two arrangements are shown in figure below. Collocated BTS Engr. Two types of BTS arrangements [] 5. To perform this function completely, the signals are encoded, encrypted, multiplexed, modulated, and then fed to the antenna system at the cell site.

Transcoding to bring kbps speech to a standard data rate of 16 kbps and then combining four of these signals to 64 kbps is essentially a part of BTS, though; it can be done at BSC or Engr. The voice communication can be either at a full or half rate over logical speech channel. The received signal from the mobile is decoded, decrypted, and equalized for channel impairments.

The channel subsequent assignment is made by BSC. Timing advance is determined by BTS. BTS signals the mobile for proper timing adjustment. Uplink radio channel measurement corresponding to the downlink measurements made by MS has to be made by BTS. Typically these directional antennas have a beam width of 65 to 85 degrees.

This increases the traffic capacity of the base station each frequency can carry eight voice channels whilst not greatly increasing the interference caused to neighboring cells in any given direction, only a small number of frequencies are being broadcast.

Typically two antennas are used per sector, at spacing of ten or more wavelengths apart. This allows the operator to overcome the effects of fading due to physical phenomena such as multipath reception. Some amplification of the received signal as it leaves the antenna is often used to preserve the balance between uplink and downlink signal.

Site Sectorization-Omni Cell site [] Figure 5. Site Sectorization-Tri Cell site [] Figure 5. Site Sectorization-Hex Cell site [] 5.

These configurations are chosen based on the rural or urban application. These configurations make the GSM system economical since the operation has options to adapt the best layout based on the traffic requirement. Thus, in some sense, system optimization is possible by the proper choice of the configuration. These include omni-directional rural configuration where the BSC and BTS are on the same site; chain and multidrop loop configuration in which several BTSs are controlled by a single remote BSC with a chain or ring connection topology; rural star configuration in which several BTSs are connected by individual lines to the same BSC; and sectorized urban configuration in which three BTSs share the same site and are controlled by either a collocated or remote BSC.

In rural areas, most BTSs are installed to provide maximum coverage rather then maximum capacity. The TRAU is the equipment in which coding and decoding is carried out as well as rate adaptation in case of data. This allows the system operator to purchase switching equipment from one supplier and radio equipment and the controller from another. This will also help reduce the complexity of the BTS. This approach allows for the maximum of flexibility and innovation in optimizing the transmission between MSC and BTS.

Figure 5. Transcoder Interfacing The transcoder is the device that takes Kbps speech or 3. First, the 13 Kbps or the data at 3. Four traffic channels can then be multiplexed on one Kbps circuit.

Then, up to 30 such Kbps channels are multiplexed onto a 2. This channel can carry up to 16x traffic and control signals. This interface uses LAPDm protocol for signaling, to conduct call control, measurement reporting, handover, power control, authentication, authorization, location update and so on.

For pdf mobile system global communication

Traffic and signaling are sent in bursts of 0. Simple description of Interfaces [] 5. The Abis interface uses multiplexing Mult or rate adaptation RA on its links.

Although there are usually transcoding units between BSC and MSC, the signaling communication takes place between these two ending points and the transcoder unit doesn't touch the SS7 information, only the voice or CS data are transcoded or rate adapted. It is a proprietary interface whose name depends on the vendor for example Ater by Nokia , it carries the A interface information from the BSC leaving it untouched.

Signaling protocol structure in GSM In the figure: Layer 1 is the physical layer, Layer 2 is the data link layer, and Layer 3 is the GSM signaling protocol. The NSS [], [] Engr. The main role of the MSC is to manage the communications between the GSM users and other telecommunication network users. The basic switching function is performed by the MSC, whose main function is to coordinate setting up calls to and from GSM users. The main difference between a MSC and an exchange in a fixed network is that the MSC has to take into account the impact of the allocation of RRs and the mobile nature of the subscribers and has to perform, in addition, at least, activities required for the location registration and handover.

The Network Switching Subsystem, also referred to as the GSM core network, usually refers to the circuit-switched core network, used for traditional GSM services such as voice calls, SMS, and circuit switched data calls. There is also an overlay architecture on the GSM core network to provide packet-switched data services and is known as the GPRS core network. All mobile phones manufactured today have both circuit and packet based services, so most operators have a GPRS network in addition to the standard GSM core network.

It connects to the subscribers through base stations and radio transmission equipment that control the air interface, and to the network of other MSCs and wireless infrastructure through voice trunks and Engr. An MSC includes the procedures for mobile registration and is generally co- sited with a visitor location register VLR that is used to temporarily store information relating to the mobile subscribers temporarily connected to that MSC.

The MSC performs the telephony switching functions of the system. It controls calls to and from other telephone and data systems. It also performs such functions as toll ticketing, network interfacing, common channel signaling, and others. It also interfaces with the PSTN. The term is only valid in the context of one call since any MSC may provide both the gateway function and the Visited MSC function; however, some manufacturers design dedicated high capacity MSCs which do not have Engr.

It thus acts as a message mailbox and delivery system The SMSC is a store-and-forward device used to provide peer-to-peer text messaging services in mobile networks. Any text message issued from a mobile handset is forwarded to the SMSC, where the location of the called subscriber is determined by consulting the appropriate HLR.

If the subscriber is currently connected to a reachable network, the location is determined and the text message is transmitted. If not, the message is stored for later transmission once the subscriber becomes available. The SMSC also includes back-end interfaces for the connection of enhanced service platforms that can be used to Engr. The HLR data is stored for as long as a subscriber remains with the mobile phone operator. The following procedures are implemented to deal with this: Each base station in the network is served by exactly one VLR; hence a subscriber cannot be present in more than one VLR at a time.

For example, the temporal mobile subscriber identity TMSI. An encryption key is also generated that is subsequently used to encrypt all wireless communications voice, SMS, etc. If the authentication fails, then no services are possible from that particular combination of SIM card and mobile phone operator attempted.

There is an additional form of identification check performed on the serial number of the mobile phone described in the EIR section below, but this is not relevant to the AUC processing. The AUC does not engage directly in the authentication process, but instead generates data known as triplets for the MSC to use during the procedure. It maintains various lists of message. The database stores the ME identification and has nothing do with subscriber who is receiving or originating call.

There are three classes of ME that are stored in the database, and each group has different characteristics: White List: This is the category of genuine equipment. Black List: This list contains all MEs with faults not important enough for barring.

It allows the network provider to operate, administer, and monitor the functioning of the BSS. The OSS is the functional entity from which the network operator monitors and controls the system. The purpose of OSS is to offer the customer cost-effective support for centralized, regional and local operational and maintenance activities that are required for a GSM network.

An important function of OSS is to provide a network overview Engr. The OMC provides alarm-handling functions to report and log alarms generated by the other network entities. The maintenance personnel at the OMC can define that criticality of the alarm. Maintenance covers both technical and administrative actions to maintain and correct the system operation, or to restore normal operations after a breakdown, in the shortest possible time. The fault management functions of the OMC allow network devices to be manually or automatically removed from or restored to service.

The status of network devices can be checked, and tests and diagnostics on various devices can be invoked. For example, diagnostics may be initiated remotely by the OMC. A mobile call trace facility can also be invoked. The performance management functions included collecting traffic statistics from the GSM network entities and archiving them in disk files or displaying them for analysis.

Communication for global system pdf mobile

Because a potential to collect large amounts of data exists, maintenance personal can select which of the detailed statistics to be collected based on personal interests and past experience. As a result of performance analysis, if necessary, an alarm can be set remotely. The OMC provides system change control for the software revisions and configuration data bases in the network entities or uploaded to the OMC.

Addresses serve to identify, authenticate, and localize subscribers, or switch connections to subscribers. Service-specific data are used to parameterize and personalize the supplementary services. The association of most important identifiers and their storage locations are summarized in figure below.

Signaling Point Code Figure 6. Bearer and Teleservice 3. Service 4. Local Mobile Service Identity Restrictions e. Parameters for additional services 6. Authentication Data Subject to Implementation Table 6. LMSI 3. Parameters for Supplementary 4. Information on Subscriber-used used for paging and cell setup Equipment if available 5. Telephony also referred to as teleservices 2. Data also referred to as bearer services Telephony services are mainly voice services that provide subscribers with the complete capability including necessary terminal equipment to Engr.

Data services provide the capacity necessary to transmit appropriate data signals between two access points creating an interface to the network. GSM Teleservices include: As standard fax machines are designed to be connected to a telephone using analog signals, a special fax converter connected to the exchange is used in the GSM system. This enables a GSM—connected fax to communicate with any analog fax in the network.

A message consisting of a maximum of alphanumeric characters can be sent to or from a mobile station. This service can be viewed as an advanced form of alphanumeric paging with a number of advantages.

If the subscriber's mobile unit is powered off or has left the coverage area, the message is stored and offered back to the subscriber when the mobile is powered on or has reentered the coverage area of the network.

This function ensures that the message will be received. A message of a maximum of 93 characters can be broadcast to all mobile subscribers in a certain geographic area. Share full text access. Please review our Terms and Conditions of Use and check box below to share full-text version of article.

Summary This chapter contains sections titled: Related Information. Email or Customer ID. Forgot password? Old Password. New Password. Your password has been changed. Returning user. The available spectrum is divided into channels A, B, C, D, and so on.

During the call, a single user will occupy completely one channel of e.

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The signaling over the network is digital, the speech is modulated analog narrow-band FM b Digital access The aim of digital networks is to have: Hence, there are eight physical channels per frequency carrier. In fact, the GSM system uses a mix of: Digital Radio Transmission System 4. As a result, different users can transmit using the same frequency, but they can't transmit at the same time. Each base station is assigned one or more carriers to use in its cell. A kHz frequency band separates the carrier frequencies from each Engr.

Normally, a 25MHz band should be divisible into carrier frequencies but in GSM the 1st carrier frequency is used as a guard band between GSM and other services that might be working on lower frequencies. Frequency Division in the Uplink Spectrum 4. Each of the carrier frequencies is divided into a ms multiframe.

A multiframe is made up of 26 frames. Two of these frames are used for control purposes, while the remaining 24 frames are used for traffic. Structure of a Multiframe 4. A normal burst is used to carry speech and data information. The structure of the normal burst is shown below. Each burst consists of 3 tail bits at each end, 2 data sequences of bits, a bit training sequence for equalization, and 8. There are 2 stealing bits 1 for each data sequence that are used by Fast Access Control Channels.

The frequency correction burst and synchronous burst have the same length as normal burst. They have different internal structures to differentiate them from normal bursts. Burst Structure 4. Organization of bursts, TDMA frames, and multiframes for speech and data [] 4.

It is used to train the MS in predicting and correcting the signal distortions due to Doppler and multipath effects in the demodulation process. The TSC has a 26, 41 or 64 bit pattern. The tail bits at the end define the end of a burst. The transmitted amplitude is ramped up from zero to a constant value over the useful period of a burst and then ramped down to zero again. Switching off will reduce interference to other RF channels.

By setting a flag, using the stealing flag bits, the receiver can distinguish between traffic user data and signaling information. Channels A channel relates to the recurrence of one burst in every frame. The channel is characterized by both its frequency and its position within the TDMA frame. This characterization is cyclical, and the channel pattern repeats every 3 hours.

There are two major categories of channels in GSM: Channels can also be classified as being dedicated or common. Dedicated channels are assigned to a mobile station, while common channels are used by idle mobile stations. In this standard, traffic channels for uplinks and downlinks are separated by 3 bursts.

Because of this, Engr. A full rate traffic channel uses 1 time slot in each of the traffic frames in a multiframe. These channels can be used by either idle or dedicated mobile stations.

Some of the common channel types are: GSM makes use of this inherent frequency agility to implement slow frequency hopping, where the mobile and BTS transmit each TDMA frame on a different carrier frequency.

The frequency hopping algorithm is broadcast on the Broadcast Control Channel. Since multipath fading is dependent on carrier frequency, slow frequency hopping helps alleviate the problem. In addition, co-channel interference is in effect randomized. Discontinuous transmission DTX is a method that takes advantage of the fact that a person speaks less that 40 percent of the time in normal conversation.

It must distinguish between voice and noise inputs, a task that is not as trivial as it appears, considering background noise. If a voice signal is misinterpreted as noise, the transmitter is turned off and a very annoying effect called clipping is heard at the receiving end.

If, on the other hand, noise is misinterpreted as a voice signal too often, the efficiency of DTX is dramatically decreased. Another factor to consider is that when the transmitter is turned off, there is total silence heard at the receiving end, due to the digital nature of GSM. To assure the receiver that the connection is not dead, comfort noise is created Engr. The paging channel, used by the base station to signal an incoming call, is structured into sub-channels. Each mobile station needs to listen only to its own sub-channel.

In the time between successive paging sub- channels, the mobile can go into sleep mode, when almost no power is used. To minimize co-channel interference and to conserve power, both the mobiles and the Base Transceiver Stations operate at the lowest power level that will maintain an acceptable signal quality. Power levels can be stepped up or down in steps of 2 dB from the peak power for the class down to a minimum of 13 dBm 20 milliwatts.

The mobile station measures the signal strength or signal quality based on the Bit Error Ratio , and passes the information to the Base Station Controller, which ultimately decides if and when the power level should be changed. Power control should be handled carefully, since there is the possibility of instability. This arises from having mobiles in co-channel cells alternatively increase their power in response to increased co-channel interference caused by the other mobile increasing its power.

These operations are described in the following sections. Radio subsystem RSS 2. Network switching subsystem SSS 3. Operation and maintenance subsystem OMS [], [] Engr. As we shall precede through our discussion on these components the architecture, other parts of the entire network will elaborate automatically. A mobile station is typically made up of: MS refers to the Mobile Phone i. This is the terminology of 2G systems like GSM.

MS can be installed in Vehicles or can be portable or handheld stations. The MS may include provisions for data communication as well as voice. A mobile transmits and receives message to and from the GSM system over the air interface to establish and continue connections through the system.

It is equivalent to the network termination of an ISDN access and is also the end-point of the radio interface. It does not contain any functions specific in GSM. The IMEI can be used to identify mobile units that are reported stolen or operating incorrectly. Just as the IMEI identities the mobile equipment, other numbers are used to identity the mobile subscriber. Different subscriber identities are used in different phases of call setup.

It is used by the land network to route calls toward an appropriate MSC. The international mobile subscribe identity IMSI is the primary function of the subscriber within the mobile network and is permanently assigned to him. The subscriber is identified in the system when he inserts the SIM card in the mobile equipment. This provides an enormous amount of flexibility to the subscribers since they can now use any GSM-specified mobile equipment.

The subscriber inserts it in the MS unit when he or she wants to use the MS to make or receive a call. The service provider if requested by the subscriber can also permanently bypass the PIN.

According to the power and applications of it, M. Their maximum allowed output power is 8 W. These terminals can emit up to 2 W of power. With evolution in technology, the maximum allowed power is reduced to 0. It is used in the case of system-internal signaling transactions in order to identify a subscriber. It is assigned only after successful subscriber authentication. Under certain condition Engr.

Here too the first two digits of the SN identify the HLR where the mobile subscriber is administrated.

Global System for Mobile Communications - Handbook of Computer Networks - Wiley Online Library

It is assigned upon demand by the HLR on a per-call basis. In conjunction with the IMSI, it is used to ensure that only authorized users are granted access to the system. The BS has a modular design and includes the: An interface is the entity responsible for communicating with MSs in a certain area. The radio equipment of a BSS may be composed of one or more cells. The base station subsystem BSS is the section of a traditional cellular telephone network which is responsible for handling traffic and signaling between Engr.

The BSS carries out transcoding of speech channels, allocation of radio channels to mobile phones, paging, quality management of transmission and reception over the air interface and many other tasks related to the radio network. Detailed BSS Components 5. It is a functional entity that handles common control functions within a BTS. BSC within a mobile network is a key component for handling and routing information. It is a high-capacity switch that provides functions such as handover, cell configuration data, and control of radio frequency RF Engr.

It assigns and releases frequencies and timeslots for all MSs in its own area. It also reallocates frequencies to the BTSs in its area to meet locally heavy demands during peak hours or on special events. The minimum power level for a mobile unit is broadcast over the BCCH. Redundancy often extends beyond the BSC equipment itself and is commonly used in the power supplies and in the transmission equipment providing the A-ter interface to PCU.

The databases for all the sites, including information such as carrier frequencies, frequency hopping lists, power reduction levels, receiving levels for cell border calculation, are stored in the BSC.

This data is obtained directly from radio planning engineering which involves modeling of the signal propagation as well as traffic projections. It performs some of the processing tasks of the BSC, but for packet data. The allocation of channels between voice and data is controlled by the base station, but once a channel is allocated to the PCU, the PCU takes full control over that channel.

The BTS is the radio equipment transceivers and antennas needed to service each cell in the network. BTS is typically able to handle three to five radio carries, carrying between 24 and 40 simultaneous communication.

Reducing the BTS volume is important to keeping down the cost of the cell sites. BTS with its antennae [] A BTS compares radio transmission and reception devices, up to and including the antennas, and also all the signal processing specific to the radio interface. There are two categorize in which, BTS may be arranged in the cells depending upon the circumstances of the region in which they are to be used. The two arrangements are shown in figure below. Collocated BTS Engr.

Two types of BTS arrangements [] 5. To perform this function completely, the signals are encoded, encrypted, multiplexed, modulated, and then fed to the antenna system at the cell site.

Transcoding to bring kbps speech to a standard data rate of 16 kbps and then combining four of these signals to 64 kbps is essentially a part of BTS, though; it can be done at BSC or Engr. The voice communication can be either at a full or half rate over logical speech channel. The received signal from the mobile is decoded, decrypted, and equalized for channel impairments. The channel subsequent assignment is made by BSC. Timing advance is determined by BTS.

BTS signals the mobile for proper timing adjustment. Uplink radio channel measurement corresponding to the downlink measurements made by MS has to be made by BTS. Typically these directional antennas have a beam width of 65 to 85 degrees. This increases the traffic capacity of the base station each frequency can carry eight voice channels whilst not greatly increasing the interference caused to neighboring cells in any given direction, only a small number of frequencies are being broadcast.

Typically two antennas are used per sector, at spacing of ten or more wavelengths apart. This allows the operator to overcome the effects of fading due to physical phenomena such as multipath reception. Some amplification of the received signal as it leaves the antenna is often used to preserve the balance between uplink and downlink signal.

Site Sectorization-Omni Cell site [] Figure 5. Site Sectorization-Tri Cell site [] Figure 5. Site Sectorization-Hex Cell site [] 5.

These configurations are chosen based on the rural or urban application. These configurations make the GSM system economical since the operation has options to adapt the best layout based on the traffic requirement. Thus, in some sense, system optimization is possible by the proper choice of the configuration. These include omni-directional rural configuration where the BSC and BTS are on the same site; chain and multidrop loop configuration in which several BTSs are controlled by a single remote BSC with a chain or ring connection topology; rural star configuration in which several BTSs are connected by individual lines to the same BSC; and sectorized urban configuration in which three BTSs share the same site and are controlled by either a collocated or remote BSC.

In rural areas, most BTSs are installed to provide maximum coverage rather then maximum capacity. The TRAU is the equipment in which coding and decoding is carried out as well as rate adaptation in case of data. This allows the system operator to purchase switching equipment from one supplier and radio equipment and the controller from another. This will also help reduce the complexity of the BTS. This approach allows for the maximum of flexibility and innovation in optimizing the transmission between MSC and BTS.

Figure 5.

Transcoder Interfacing The transcoder is the device that takes Kbps speech or 3. First, the 13 Kbps or the data at 3.

Four traffic channels can then be multiplexed on one Kbps circuit. Then, up to 30 such Kbps channels are multiplexed onto a 2. This channel can carry up to 16x traffic and control signals.

This interface uses LAPDm protocol for signaling, to conduct call control, measurement reporting, handover, power control, authentication, authorization, location update and so on. Traffic and signaling are sent in bursts of 0. Simple description of Interfaces [] 5. The Abis interface uses multiplexing Mult or rate adaptation RA on its links. Although there are usually transcoding units between BSC and MSC, the signaling communication takes place between these two ending points and the transcoder unit doesn't touch the SS7 information, only the voice or CS data are transcoded or rate adapted.

It is a proprietary interface whose name depends on the vendor for example Ater by Nokia , it carries the A interface information from the BSC leaving it untouched. Signaling protocol structure in GSM In the figure: Layer 1 is the physical layer, Layer 2 is the data link layer, and Layer 3 is the GSM signaling protocol.

The NSS [], [] Engr.