GSM_3GPP of knowledge of mobile communication

http://www921lj.blog.163.com/blog/static/477114502009518520360/

GSM System composition

Mobile Station MS, base station subsystem BSS and network subsystem NSS constitute the entity part of GSM system. Operational Support Systems (OSS) provide a means for the operations department to control and maintain these actual operational components.

1. Mobile Station (MS)
The type of mobile station includes not only a handheld platform, but also a car-mounted platform and a portable platform. Another important component of the
Mobile console is the user Identification Module (SIM), which is essentially an ISO-compliant "smart" card that contains all the information about the user and some of the wireless interfaces, including authentication and encryption information. GSM-standard mobile stations need to be inserted into the SIM card, only when handling unusual emergency calls, you can operate the mobile station without the SIM card. The application of the SIM card makes the mobile station not fixed to a user, so the GSM system is used to identify the mobile phone users through the SIM card, which lays the foundation for the future development of personal communication. The
2. Base station subsystem (BSS)
Base station subsystem is connected to the Mobile Service Switching Center (MSC) in the Network Path System (NSS) to achieve communication connections between mobile users or between mobile users and fixed network users, and to transmit system signals and user information. Of course, the BSS section should be operated and maintained, and the communication connection between BSS and Operation support Subsystem (OSS) should be established. The
Base station subsystem is composed of functional entities in both the Base station transceiver (BTS) and the base station controller (BSC).
3. Network Path System (NSS)
Network Path System (NSS) mainly includes the GSM system Exchange function and for user data and mobility management, security management required database functions, It plays a role in the management of communication between GSM mobile Subscriber and GSM mobile user and other communication network users. NSS is composed of a series of functional entities, the entire GSM system, that is, NSS between the functional entities and NSS and BSS through the CCITT signaling system No.7 Protocol and GSM code 7th signaling network communication.
4. Operational Support Subsystem (OSS)
Operational Support Subsystem (OSS) requires many tasks, including mobile user management, mobile device management, and network operation and maintenance.
Mobile User management can include user data management and call billing. User data management generally by the attribution user position Register (HLR) to complete this task, HLR is one of NSS functional entities. User identification Card SIM management can also be considered as a part of user data management, but as a relatively independent user identification card SIM management, but also in accordance with the operating department of the SIM management requirements and mode of the use of dedicated SIM personalized equipment to complete. Call billing can be handled separately by each mobile Service Exchange Center MSC and Gmsc accessed by mobile users, or by centralized processing of billing data through HLR or independent billing devices.
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Main interface of GSM system
The main interface of GSM system refers to a interface, Abis interface and UM interface. The definition and standardization of these three main interfaces can ensure that the mobile station, base station subsystem and network path system equipment produced by different suppliers can be integrated into the same GSM digital mobile communication Network for operation and use.
(1) A interface
A interface is defined as the communication interface between the network path System (NSS) and the base station subsystem (BSS), which is the interconnection interface between the mobile Service Exchange Center (MSC) and the base station controller (BSC), and its physical link is passed through the adoption of standard 2.048MB/S PCM Digital transmission link to achieve. The information passed by this interface includes mobile station management, base station management, mobility management, and continuous management.
(2) Abis interface
The Abis interface is defined as the communication interface between the two functional entity base station controllers (BSc) and the base station transceiver (BTS) for the base station subsystem for the remote interconnection of BTS (not with BSC) and BSc, physical links by using standard 2.048mb/s or 64kbit/s PCM Digital transmission link to achieve. The BS interface shown in Figure 3-4 is a special case of the Abis interface for direct interconnection between BTS (and BSc) and BSc, at which point the distance between BSc and BTS is less than 10 m. This interface supports all services provided to the user and supports the control of BTS wireless devices and the distribution of wireless frequencies.
(3) UM interface (Empty interface)
The Um interface (air interface) is defined as the communication interface between the mobile station and the base station transceiver (BTS) for interoperability between the mobile station and the fixed part of the GSM system, and the physical link is realized through the wireless link. The information passed by this interface includes wireless resource management, mobility management, and continuity management.

The interface between GSM system and other public telecommunication network
Other public telecommunication networks mainly refer to public telephone networks (PSTN), Integrated Services Digital Networks (ISDN), packet-switched public data networks (PSPDN) and circuit-switched public data networks (CSPDN). GSM systems are interconnected with these public telecommunication networks through MSC, and their interfaces must meet CCITT's relevant interfaces and signalling standards and the interfaces and signaling standards developed by the various national posts and telecommunications departments in connection with these telecommunications networks.
According to the development of the existing public telephone network (PSTN) and the development foreground of the Integrated Service Digital Network (ISDN), the interconnection mode of GSM system and PSTN and ISDN network adopts the 7th Signal signaling system interface. Its physical link is achieved through the PCM digital transmission of the standard 2.048MBIT/S between MSC and PSTN or ISDN switches.
If you have an ISDN switch, you can establish a direct signalling interface between HLR and ISDN to enable the ISDN switch to ask the HLR for location information directly from the Mobile user's ISDN number to establish a call route to the current registered MSc in the Mobile station.
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Zone definition
In the mobile communication network of the community, the base station is set up many, the mobile station does not have the fixed position, as long as the mobile user is in the service area, no matter where to move, the mobile communication network must have the Exchange control function to realize the performance of position update, handoff and automatic roaming.
Service
Service area refers to the region where the mobile station can be serviced, that is, the area in which users of different communications networks (such as PLMN, PSTN or ISDN) can communicate without knowing the actual location of the mobile station.
A service area may consist of one or several communal terrestrial mobile communications networks (PLMN), which can be part of a country or a country or a number of countries.
Public Land Mobile Communication Network (PLMN)
PLMN is a geographical area of communication services provided by a public land mobile communication Network (PLMN). PLMN can be considered an extension of a network, such as an ISDN or PSTN, and a PLMN area can consist of one or more mobile service Exchange centers (MSC). The area has a common numbering system (e.g. the same domestic area number) and a common routing plan. MSC forms the functional interface between fixed network and PLMN, for call continuation and so on.
MSC Area
MSC is a part of a PLMN network that is covered by a common area of all communities controlled by a mobile service exchange center. An MSc area can consist of one or several location areas.
Location Area
The location area refers to the area where the mobile station can be moved arbitrarily without the need for location updates. A location area may consist of one or more cells (or base station areas). In order to call the mobile station, a paging signal can be sent at all base stations in one location area.
Base Station Area
The area covered by all the cells that are included in one or more base station transceiver (BTS) sites that are placed at the same base site.
Community
A wireless coverage area identified by a base station identification code or a global community identification. When the omni-direction antenna structure is adopted, the cell is the base station area.

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Mobile identification number
IMSI (International Mobile subscriber Identity):
IMSI is the only identification number that the GSM system assigns to mobile users (MS), and this code is valid in all locations, including in the roaming area.
Adopt e.212 encoding method.
Stored in SIM cards, HLR, and VLR and transmitted over the wireless interface and the map interface.
Mcc:mobile Country Code, mobile Country code, three digits, such as China for 460.
Mnc:mobile Network Code, mobile network number, two digits, such as China Post and telecommunications MNC 00.
Msin:mobile Subscriber Identification number, a unique identification code for MS in a PLMN. The encoding format is: H1 H2 H3 S XXXXXX
Nmsi:national Mobile Subscriber identification, a unique identification code for MS in a country.
Typical examples of IMSI: 460-00-4777770001
IMSI Distribution principle:
Contains a maximum of 15 digits (0-9).
MCC is uniformly distributed around the world, and the distribution of Nmsi is the business of all countries.
If there is more than one GSM PLMN in a country, each PLMN is assigned a unique MNC.
When IMSI is allocated, it is necessary to follow the principle of PLMN most analytical MCC+MNC in foreign countries.
Updatelocation, Purgems, sendauthenticationinfo must be addressed with IMSI
Restoredata is typically addressed with IMSI, and all the current operations to HLR complement operations are IMSI addressed.
Tmsi (Temporary Mobile subscriber Identity):
Tmsi is a temporary user identification allocated within VLR in order to enhance the confidentiality of the system, and it is uniquely corresponding to IMSI within a VLR region.
Tmsi Distribution principle:
Contains four bytes, which can be made up of eight hexadecimal digits, and the structure can be determined by the Operations department depending on the local situation.
The Tmsi 32 bits cannot be all 1, because the tmsi representing a bit full of 1 in the SIM card indicates an invalid Tmsi.
To avoid tmsi duplication after a VLR reboot, you can take a part of Tmsi to represent the time or a specific bit of change after the VLR is restarted.
Lmsi (local Mobile subscriber Identity):
Lmsi is designed to speed up the query speed of VLR user data and is allocated by VLR when the location is updated, then sent to HLR with IMSI, and HLR will not do anything with it, but will send it to IMSI in any message containing VLR.
The length of the Lmsi is four bytes, with no specific allocation principle required, and its structure is determined by the operating departments.
MSISDN (Mobile subscriber International isdn/pstn number):
MSISDN refers to the call user to call the GSM PLMN a mobile user needs to dial the number, the role of fixed network PSTN number
Adopt E.164 Encoding method
stored in HLR and VLR, transmitted on the map interface
Structure Description:
Cc:country Code, country code, such as China for 86.
Ndc:national destination code, the domestic access number, such as China Mobile NDC currently have 139, 138, 137, 136, 135.
Sn:subscriber number
The general format for MSISDN is 86-139 (or 8-0)-h1 H2 H3 ABCD
Typical MSISDN for example: 861394770001
Sendroutinginfo and Sendimsi are all MSISDN addressed.
In China, the mobile subscriber number is up to 11 digits and a H0 (0~9) is added to the front of the h1h2h3, and its general format becomes 86-139 (or 8-0)-H0H1H2H3ABCD, typical number example: 8613904770001
Msc-number (MSC number)/vlr-number (VLR number)
Adopt E.164 Encoding method
The encoding format is
Cc+ndc+lsp
where cc, NDC meaning and MSISDN, LSP (lacally significant part) by the operator's own decision.
Typical msc-number for 86-139-0477.
Performhandover and Preparehandover are all msc-number addressed.
Currently online MSC and VLR are all in one, so msc-number and Vlr-number are basically the same
In China, both MSC and VLR numbers have been upgraded, with a 0 in front of m1m2m3, a typical number for example: 8613900477
Sendidentification, Cancellocation, Insertsubscriberdata, Deletesubscriber Data, Reset, Operations such as Provideroamingnumber must be vlr-number addressed, while sendparameters operations can be addressed with Vlr-number.
Roaming-number (roaming number) and Handover-number (toggle number)
Roaming-number abbreviation msrn,handover-number abbreviation Hon
Temporarily allocated during a move call or switch, which is used for gmsc addressing vmsc or Msca addressing MSCB and is released immediately after the continuation completes. It is not visible to the user.
Adopt E.164 Encoding method
The encoding format is: Add a few bytes to the back of the Msc-number
Typical roaming-number or Handover-number for 86-139-0477xxx
Due to the MSISDN number, MSC number, VLR number has been promoted, MSRN and Hon also with the rise, the typical number of MSRN and hon after the promotion of 86-139-00477ABC
There are two types of allocations for MSRN:
When the starting registration or location is updated, the MSRN is transferred to the HLR by the VLR distribution. When the mobile station leaves the site, delete the MSRN in both VLR and HLR so that the number can be reassigned to other roaming users.
At each mobile station when there is a call to the phone, according to HLR request, temporarily by VLR assigned a MSRN, this number can only be in a certain time range (such as 90 seconds) valid.
For Hon, it is a temporary number used when switching between two mobile switching areas (MSC) to establish a call link between MSc.
Hlr-number (HLR number)
Adopt E.164 Encoding method
The encoding format is
CC+NDC+H1 H2 H3 0000, after the rise, changed to: cc+ndc+h0h1h2h3000
Which cc,ndc meaning and MSISDN provisions.
The typical hlr-number is 86-139-4770000, and the ascending position is 861390477000.
Operations that are addressed with IMSI can be converted to Hlr-number addressing with the exception of the required
LAI (Location area identification--location)
When detecting location updates, use the location area to identify Lai.
MCC is the same as MNC and IMSI.
Lac:location area code, which is 2 byte long hexadecimal BCD code, 0000 and Fffe cannot be used.
CGI (Cell Global identification--Community recognition)
CGI is the only identification of all GSM PLMN, which is based on the identification of Lai in the location area and the identification of CI in the community.
The encoding format is LAI+CI
Ci:cell Identity is a 2-byte hexadecimal BCD code that can be customized by the operations department.
Rszi (regional Subscription Zone Identity)
Rszi explicitly defines the areas that the user can roam
? CC and NDC have the same meaning as in msisdn.
ZC (Zone Code) uniquely identifies the area that is allowed to roam within a plmn, which is set by the operator and stored within the VLR.
Rszi is not transmitted between HLR and VLR, and only ZC is transferred from HLR to VLR when the location is updated, for VLR to determine whether a user is allowed to roam within the VLR zone.
Bsic (Base station identification color code)
For mobile stations to identify adjacent, using the same carrier, different base station transceiver (BTS), especially to distinguish in different countries in the border region with the same carrier frequency of adjacent BTS. The Bsic is a 6-bit encoding, which is composed as shown in Figure 4-6.
NCC----PLMN color codes. Used to uniquely identify different plmn in neighboring countries. Neighboring countries should specifically coordinate the NCC configuration.
BCC----BTS color code. Used to uniquely identify the same carrier, adjacent, different BTS.
IMEI (International Mobile device Identification code)
IMEI uniquely identifies a mobile device that is used to monitor stolen or invalid mobile devices. The composition of the IMEI is shown in Figure 4-7:
The composition of the IMEI
TAC----Model approval code, which is assigned by the European Model approval Center.
FAC----Final assembly code, indicating the manufacturer or the final assembly location, which is encoded by the manufacturer.
SNR----ordinal number. The independent ordinal number of this number uniquely identifies each of the mobile devices for each TAC and FAC.
SP-------Standby.