1. GPRS overview
GPRS (General Packet Radio Service) is the abbreviation of General Packet Radio Service. It is a high-efficiency method based on packet switching to transmit data. GPRS will profoundly change the end user's experience of using mobile data computing. The most obvious advantage of GPRS is that it can provide a higher data rate than the existing GSM network of 9.6kbit / s, up to 170kbit / s. The huge throughput changes a single text-oriented wireless application, making multimedia services including pictures, voice and video a reality. Mobile users no longer have to dial a special ISP (Internet Service Provider) to send and receive E-mail and browse the web
Page, GPRS provides a seamless and direct Internet connection. GPRS supports the X.25 protocol and the IP protocol that has a profound impact on the Internet. For the existing circuit-switched data service (CSD) and short message service (SMS) of the GSM network, GPRS is a supplement rather than a substitute. GPRS flexibly and dynamically allocates wireless resources according to user needs, so as to achieve multi-user sharing and improve frequency utilization. At the same time, the charging will be changed from the traditional on-time method to charging based on the transmission volume of user data. GPRS is not only supported by GSM, the second generation mobile communication system in Europe, but also by IS-136 in North America. Its high data rate can provide part of the multimedia services in the third generation and is several years ahead of time, and when the third generation really arrives, for those operators who do not have the third generation operating rights, GPRS is still It is a competitive business, so GPRS is considered to be an important step in the evolution of the second generation mobile communication system to the third generation. At present, several major telecommunications companies such as Nokia, Motorola,
Simens and others are actively participating in the provision of GPRS.
2. The logical structure of GPRS
Logically, GPRS can be implemented by adding two new network nodes to the GSM network structure. The two nodes are:
* GPRS service support node (Serving GPRS support node, SGSN);
* GPRS gateway support node (Gateway GPRS support node, GGSN).
The GSM standard 03.60 defines a new interface between the new node and the new node and the original node of the GSM network, as shown in Figure 1.
Related pictures on this topic are as follows:
Figure 1 The logical structure of GPRS ...... Signaling interface-signaling and data transmission interface
The support node GSN (GPRS Support Node) has all the functions to support GPRS. Allow multiple in a PLMN
GSN.
The packet data network analyzes the address of the PDP (Packet Data Protocol) and accesses the GPRS network from the GGSN. The GGSN is responsible for storing the routing information of users who have attached the GPRS service, and according to this information, the PDUs (Protocol
Data Units) is sent to the current registration point of the MS through the tunnel technology, that is, the SGSN. GGSN can pass Gc
The interface (if present) queries the current location information of the mobile user from the HLR. GGSN is PDN (Packed Data Network)
The first node interconnected with a GSM PLMN that supports GPRS (ie, the Gi reference point is supported by GGSN).
The SGSN is the node that is currently providing services to the MS (that is, the Gb interface is supported by the SGSN). When the GPRS service is activated, the SGSN is responsible for establishing information about mobility and security and confidentiality with the MS. When the PDP information is activated, the SGSN is responsible for establishing PDP information for routing with the GGSN.
The functions of SGSN and GGSN can be realized by a physical node, or they can be implemented on different physical nodes.
They should all have IP routing capabilities and be able to connect to IP routers. When the SGSN and GGSN are located in different PLMNs, they are interconnected through the Gp interface. The Gp interface has all the functions of the Gn interface and the security functions required for communication between PLMNs. Through the Gs interface, the SGSN can transmit the location information of the MS to the MSC / VLR, and can listen to the paging request from the MSC / VLR.
3. Mobility Management (MM) function in GPRS
GPRS MM functions include activation, deactivation, security and confidentiality, location management, user management and so on. The mobility management of GPRS users is reflected in the MS
Related pictures on this topic are as follows:
Figure 2 Mobility management state model The mutual conversion between the three MM states. The three states are: idle, standby, and ready.
The MS at a certain moment is always in one of three states (see Figure 2 for the state transition relationship).
In the idle state, the user has not activated GPRS mobility management. The MS and SGSN have not yet stored the user's effective location information or routing information. At this time, no mobility management related to the user is performed, and the MS cannot receive except PTM-M (Point To
Any news other than MulTIpoint-MulTIcast). When the MS initiates an activation request to the SGSN and is accepted, the MS moves to the ready state. At this time, the MS can receive / send PDP (Packet Data Protocol) PDUs and can receive PTM-M and PTM-
G (Point To MulTIpoint-Group) message. In the ready state, regardless of whether wireless resources are allocated to users or not, even if no data is sent, the MM contact should always be maintained. There is a special timer for monitoring activities in the ready state. When the timer expires, the MS changes to the standby state. After the MS sends a request to deactivate GPRS to SGSNA and is accepted, the MS goes to idle state.
In the standby state, MS and SGSN have established MM context (Intertext) for the user's IMSI (InternaTIonal Mobile Station Identity). At this time, the MS can receive PTM-M and PTM-G data, and also can receive messages and signaling of paging PTP or PTM-G and messages of paging CS (Circuit Switched) service sent by the SGSN. But MS can't send / receive
PTP data and transfer PTM-G data. When the MS responds to the paging message, the MS transitions to the ready state, and the SGSN transitions to the ready state when receiving the paging response returned by the MS.
The MM information stored in the MS includes IMSI, MM status (idle, ready or waiting), P-TMSI (Packet Temporary
Mobile Subscriber Identity), P-TMSI signature (for identity verification, current routing area (RA), current cell identification (CI), currently used key Kc, key serial number CKSN, encryption algorithm, PDP information, etc. MSC / Storage in VLR
IMSI, SGSN number. HLR stores IMSI, MSISDN, SGSN number, SGSN address, GGSN list, PDP information, etc.
SGSN stores IMSI, MM status, P-TMSI, P-TMSI signature, IMEI (International Mobile Equipment
Identity), MSISDN, RA, CI, Kc, CKSN, encryption algorithm, PDP information, etc.
The mobile management protocol is composed of three parts. They are the LLC and RLC / MAC protocols adopted by the Um interface, the MAP protocol adopted between the SGSN and HLR (Gr), the SGSN and EIR (Gf), the SGSN and MSC / VLR Gs) between BSSAP + agreement.
The following highlights the activation process and location management process in MM.
(1) Activation process â‘ The MS sends an activation request message to the new SGSN, which includes P-TMSI + old RAI (used when no P-TMSI is available)
IMSI), CKSN, activation type (only one of GPRS activated, GPRS activated when IMSI has been activated, GPRS / IMSI joint activation), DRX parameters, old P-TMSI signature.
② The new SGSN sends an identity authentication request message (P-TMSI, old RAI, old P-TMSI signature) to the old SGSN to obtain the MS ’s
IMSI. The old SGSN sends back an authentication response message (IMSI, three-parameter group for authentication). If the old SGSN cannot authenticate the MS, the corresponding cause of error will be sent back.
â‘¢If neither the new nor the old SGSN can authenticate the MS, the new SGSN will send an authentication request message to the MS (authentication type = IMSI),
The MS sends back a response message (IMSI).
â‘£ Confidential authentication between MS, new SGSN and HLR.
⑤ Perform IMEI inspection between MS, new SGSN and EIR.
â‘¥If the SGSN number has been changed during the initial activation or re-activation (compared to the last time), the SGSN should notify the HLR. From new
SGSN sends location update message (SGSN number, SGSN address, IMSI) to HLR; HLR sends location elimination message to old SGSN
(IMSI, elimination type); old SGSN response (IMSI); HLR sends insert user data message (IMSI, GPRS user data) to the new SGSN; the new SGSN checks the legality of the MS in the new RA, if the MS is a locally restricted user and If activation in the new RA is not allowed, the new SGSN returns a response (IMSI, SGSN area restricted) to the HLR, refusing the activation request. If the activation is not allowed for other reasons, the response (IMSI, reason) is returned to the HLR. If the MS is legal, it will return an answer (IMSI); HLR
The SGSN sends back a location update response.
⑦If the activation type in point ①is the latter two (activate GPRS, GPRS / IMSI joint activation when IMSI is activated), when the Gs interface between SGSN and MSC / VLR exists, update the VLR. The VLR number is obtained from RA. The new SGSN sends a location update request message (new LAI, IMSI, SGSN number, location update type) to the new MSC / VLR; the new VLR sends the HLR
Request location update (IMSI, new VLR); HLR notifies old VLR to eliminate location information (IMSI); old VLR responds to HLR
(IMSI); HLR sends the insert user data message (IMSI, GSM user data) to the new MSC / VLR; the new VLR answers the HLR
(IMSI). At this time, the new MSC / VLR sends a location update acceptance response (VLRTMSI) to the new SGSN.
⑧ The new SGSN sends an activation accept message (P-TMSI, VLRTMSI, P-TMSI signature) to the MS.
⑨ The MS sends an activation complete message (P-TMSI, VLRTMSI) to the new SGSN.
â‘© The new SGSN sends a TMSI reallocation complete message (VLRTMSI) to the new MSC / VLR.
(2) Location management process
The MS compares the received CI and RAI with the stored CI and RAI, and if a difference is found, it needs to initiate a location update request.
When the MS is in the ready state, a cell update request is initiated when the CI changes. When the MS is in the waiting state, it can only initiate RA
Update request, and when the CI changes within the same RA, the update request cannot be initiated. RA update is divided into SGSN internal RA update and SGSN
There are two types of RA updates. Here is a more complicated update of RA between SGSNs.
â‘ MS requests RA update from the new SGSN (old RAI, old P-TMSI signature, update type).
â‘¡ The new SGSN sends a request to the old SGSN to obtain the MM and PDP information of the MS (old RAI, TLLI, old P-TMSI signature, new SGSN
Address), the old SGSN responds.
â‘¢ Conduct security and confidentiality verification between MS, new SGSN and HLR.
â‘£ The new SGSN informs the old SGSN that it is ready to receive the activated PDP information.
⑤ The old SGSN forwards the stuck packet units to the new SGSN.
â‘¥ The new SGSN sends a PDP update request (new SGSN address, TID (Tunnel Identifier), negotiated QoS) to the GGSN,
GGSN response (TID).
⑦ The new SGSN requests location updates from the HLR (SGSN number, SGSN address, IMSI).
⑧ The HLR informs the old SGSN of the cancellation location (IMSI, cancellation type) and the old SGSN responds (IMSI).
⑨ The HLR sends an insert user data message (IMSI, GPRS user data) to the new SGSN, and the new SGSN responds (IMSI).
â‘© HLR responds to the location update request of the new SGSN (IMSI).
The new SGSN sends an RA update acceptance message (P-TMSI, P-TMSI signature, received N-PDU number) to the MS.
The MS sends the RA update complete message (P-TMSI, received N-PDU number) to the new SGSN.
4 Conclusion
GPRS is an advanced service capable of providing high-speed data, and its operation and implementation will take a big step towards the third-generation mobile communication that provides multimedia services. The position of the MS in mobile communication is always changing frequently, which in turn affects the management of users, the allocation of wireless resources, the establishment of communication connections, etc. Therefore, mobility management (MM) is a crucial issue to study mobile in GPRS Sexual management is far-reaching.
The planning of IP addresses in the GPRS network In the GPRS backbone network, the IP protocol is used at the network layer, and each SGSN and GGSN has an internal IP address for communication within the backbone network. When each GPRS terminal is connected to an external data network, such as an IP network, a corresponding IP address is required. Therefore,
The IP address is an important resource of the GPRS network, which is used for the identification of network equipment and users. Good address planning is very important for the development and maintenance of the network.
The IP address of the GPRS network can be divided into two cases: the address of the internal GPRS backbone network and the address required to connect to the Internet.
The first type is used for SGSN, GGSN, BG, DNS, DHCP, CG, network management equipment, all routers and WAP gateways used, and can use the reserved address specified in the RFCl597 file.
The reserved address is divided into three segments:
10.0.0.0 --- 10.255.255.255 (1 class A address);
172.16.0.0 --- 172.31.255.255 (16 connected Class B addresses);
192.168.0.0 --- 192.168.255.255 (256 connected Class C addresses).
The second type of address is a public IP address. These addresses are required for interconnection with the Internet. If the operator connects the GPRS network only to the Internet as a bearer network, the public IP is provided by IAP; if the operator also provides services as an ISP,
You need to apply to CNNICC for a public IP address.
The general address allocation principles are as follows:
a. The allocated addresses should meet the needs as soon as possible, and make the addresses as continuous as possible to reduce the size of the routing table.
b. Addresses need to be managed in a unified manner, allocated on demand and ensure effective use. The number of allocated addresses is allocated according to the principle that the utilization rate of the IP address of the application system reaches 25% in the initial stage and more than 50% in one year.
c. Network equipment (routers and GGSN) must support classless inter-domain routing technology (CIDR, Class Inter Domain)
Routing) and variable length subnet mask (VLSM, Variable Length Subnet Mask) technology, less than the number of network hosts
127 is generally assigned by subnet address, and the subnet mask is determined according to the actual number of hosts in the application system.
GPRS abbreviation
A
AA-Anonymous access
APN-Access point name
ARP-Address Resolution Protocol
ARQ-Automatic request resend
ATM-asynchronous transfer mode
AuC-Authentication Center
B
BB-backbone network carrying circuit
BCCH-Broadcast Control Channel
BCF-Base station control function
BCS-block check sequence
BEC-backward error correction
BG-Border Gateway
BS-billing system
BSC-Base Station Controller
BSS-Base Station Subsystem
BSSGP-GPRS Base Station Subsystem Agreement
BTS-Base Transceiver
BVC-BSSGP virtual connection
BVCI-BSSGP virtual connection identification
C
CG-billing gateway
CGF-billing gateway function
CGI-Community Global Identification
CI-cell identity
CLNP-connectionless network protocol
CLNS-connectionless network service
CMIP-General Management Information Protocol
CONS-connection-oriented network protocol
CRC-cyclic redundancy code check
CS-circuit switching, coding scheme
CU-cell upgrade
D
DB-Database
DL-downlink
DLCI-Data link connection identification
DNIC-Data Network Identification Code
DNS-Domain Name System
E
EIR-device identification register
ETSI-European Telecommunications Standards Committee
F
F / W-Firewall
FH-frame header
FTP-File Transfer Protocol
G
GGSN-gateway GPRS support node
GMSC-Gateway MSC
GPRS-General Packet Radio Service
GRE-General routing package
GSM-Global Mobile Communication System
GSN-GPRS support node
GTP-GPRS tunnel protocol
I
IMEI-International Mobile Equipment Identifier
IMSI-International Mobile User Identifier
IP-Internet protocol
IPv4-Internet Protocol version 4
IPv6-Internet Protocol version 6
ISP-Internet service provider
L
LAC-location area code
LAN-Local Area Network
LLC-Logical Link Control
LLM-logical link management
LLME-Logical Link Management Entity
M
MAC-Media Access Control
MCC-mobile service country code
MNC-Mobile network code
MO-Mobile calling
MS-Mobile Station
MSC-Mobile Switching Center
MT-mobile terminal
MTP2-message layer 2
MTP3-Message Transport Layer 3
N
NE-Network Unit
NFS-Network File System
NGAF-non-GPRS warning sign
NMG-Network Management Gateway
NMN-Network Management Node
N-PDU-Network Protocol Data Unit
NSE-Network Business Entity
NSS-network switching subsystem
O
OMC-Operation and Maintenance Center
OSF-operating system function
OSI-Open System Interconnection
P
PACCH-packet combination control channel
PAGCH-packet access confirmation channel
PBCCH- packet broadcast control control channel
PC-power control
PCCCH-packet shared control channel
PCU-group control unit
PDC-packet data communication
PDCH-packet data channel
PDN-packet data network
PDP-Packet Data Agreement
PDTCH-packet data traffic channel
PDU-protocol data unit
PL-Physical Link
PPP-point-to-point protocol
PSDN-Packet Exchange Database
PSPDN-packet switched public data network
PSTN-Public Switched Telephone Network
PTM SC-point-to-multipoint service center
PTM-point to multipoint
PTM-G-point-to-point-group call
PTM-M-point-to-multipoint-broadcast
P-TMSI-packet TMSI
PTP-point-to-point
PVC-permanent virtual circuit
Q
QoS-quality of service
R
RLC-Wireless Link Control
S
SAP-Service Access Point
SC-Business Center
SDU-Service Data Unit
SGSN-service GPRS support node
SIM-User ID Card
SMS-short message service
SM-SC-Short Message-Business Center
SMSS-Exchange and Management Subsystem
SNDC-Subnet Independent Convergence
SNDCP-Subnet Independent Convergence Protocol
SS # 7-7 signaling system
SVC-switched virtual circuit
T
TA-Pre-timing
TCP-Transmission Control Protocol
TDMA-time division multiple access
TEPI-Tunnel Endpoint Identification
Tunnel endpoint identification in TEPIG-GGSN
Tunnel endpoint identification in TEPIS-SGSN
TID-Tunnel Identification
TLLI-Temporary logical link identification
TRAU-transcoder and rate adaptation unit
TRX-Transmitter-Receiver
U
UDP-User Datagram Protocol
UL-uplink
V
VPN-Virtual Private Network
GPRS (General Packet Radio Service) is the abbreviation of General Packet Radio Service. It is a high-efficiency method based on packet switching to transmit data. GPRS will profoundly change the end user's experience of using mobile data computing. The most obvious advantage of GPRS is that it can provide a higher data rate than the existing GSM network of 9.6kbit / s, up to 170kbit / s. The huge throughput changes a single text-oriented wireless application, making multimedia services including pictures, voice and video a reality. Mobile users no longer have to dial a special ISP (Internet Service Provider) to send and receive E-mail and browse the web
Page, GPRS provides a seamless and direct Internet connection. GPRS supports the X.25 protocol and the IP protocol that has a profound impact on the Internet. For the existing circuit-switched data service (CSD) and short message service (SMS) of the GSM network, GPRS is a supplement rather than a substitute. GPRS flexibly and dynamically allocates wireless resources according to user needs, so as to achieve multi-user sharing and improve frequency utilization. At the same time, the charging will be changed from the traditional on-time method to charging based on the transmission volume of user data. GPRS is not only supported by GSM, the second generation mobile communication system in Europe, but also by IS-136 in North America. Its high data rate can provide part of the multimedia services in the third generation and is several years ahead of time, and when the third generation really arrives, for those operators who do not have the third generation operating rights, GPRS is still It is a competitive business, so GPRS is considered to be an important step in the evolution of the second generation mobile communication system to the third generation. At present, several major telecommunications companies such as Nokia, Motorola,
Simens and others are actively participating in the provision of GPRS.
2. The logical structure of GPRS
Logically, GPRS can be implemented by adding two new network nodes to the GSM network structure. The two nodes are:
* GPRS service support node (Serving GPRS support node, SGSN);
* GPRS gateway support node (Gateway GPRS support node, GGSN).
The GSM standard 03.60 defines a new interface between the new node and the new node and the original node of the GSM network, as shown in Figure 1.
Related pictures on this topic are as follows:
Figure 1 The logical structure of GPRS ...... Signaling interface-signaling and data transmission interface
The support node GSN (GPRS Support Node) has all the functions to support GPRS. Allow multiple in a PLMN
GSN.
The packet data network analyzes the address of the PDP (Packet Data Protocol) and accesses the GPRS network from the GGSN. The GGSN is responsible for storing the routing information of users who have attached the GPRS service, and according to this information, the PDUs (Protocol
Data Units) is sent to the current registration point of the MS through the tunnel technology, that is, the SGSN. GGSN can pass Gc
The interface (if present) queries the current location information of the mobile user from the HLR. GGSN is PDN (Packed Data Network)
The first node interconnected with a GSM PLMN that supports GPRS (ie, the Gi reference point is supported by GGSN).
The SGSN is the node that is currently providing services to the MS (that is, the Gb interface is supported by the SGSN). When the GPRS service is activated, the SGSN is responsible for establishing information about mobility and security and confidentiality with the MS. When the PDP information is activated, the SGSN is responsible for establishing PDP information for routing with the GGSN.
The functions of SGSN and GGSN can be realized by a physical node, or they can be implemented on different physical nodes.
They should all have IP routing capabilities and be able to connect to IP routers. When the SGSN and GGSN are located in different PLMNs, they are interconnected through the Gp interface. The Gp interface has all the functions of the Gn interface and the security functions required for communication between PLMNs. Through the Gs interface, the SGSN can transmit the location information of the MS to the MSC / VLR, and can listen to the paging request from the MSC / VLR.
3. Mobility Management (MM) function in GPRS
GPRS MM functions include activation, deactivation, security and confidentiality, location management, user management and so on. The mobility management of GPRS users is reflected in the MS
Related pictures on this topic are as follows:
Figure 2 Mobility management state model The mutual conversion between the three MM states. The three states are: idle, standby, and ready.
The MS at a certain moment is always in one of three states (see Figure 2 for the state transition relationship).
In the idle state, the user has not activated GPRS mobility management. The MS and SGSN have not yet stored the user's effective location information or routing information. At this time, no mobility management related to the user is performed, and the MS cannot receive except PTM-M (Point To
Any news other than MulTIpoint-MulTIcast). When the MS initiates an activation request to the SGSN and is accepted, the MS moves to the ready state. At this time, the MS can receive / send PDP (Packet Data Protocol) PDUs and can receive PTM-M and PTM-
G (Point To MulTIpoint-Group) message. In the ready state, regardless of whether wireless resources are allocated to users or not, even if no data is sent, the MM contact should always be maintained. There is a special timer for monitoring activities in the ready state. When the timer expires, the MS changes to the standby state. After the MS sends a request to deactivate GPRS to SGSNA and is accepted, the MS goes to idle state.
In the standby state, MS and SGSN have established MM context (Intertext) for the user's IMSI (InternaTIonal Mobile Station Identity). At this time, the MS can receive PTM-M and PTM-G data, and also can receive messages and signaling of paging PTP or PTM-G and messages of paging CS (Circuit Switched) service sent by the SGSN. But MS can't send / receive
PTP data and transfer PTM-G data. When the MS responds to the paging message, the MS transitions to the ready state, and the SGSN transitions to the ready state when receiving the paging response returned by the MS.
The MM information stored in the MS includes IMSI, MM status (idle, ready or waiting), P-TMSI (Packet Temporary
Mobile Subscriber Identity), P-TMSI signature (for identity verification, current routing area (RA), current cell identification (CI), currently used key Kc, key serial number CKSN, encryption algorithm, PDP information, etc. MSC / Storage in VLR
IMSI, SGSN number. HLR stores IMSI, MSISDN, SGSN number, SGSN address, GGSN list, PDP information, etc.
SGSN stores IMSI, MM status, P-TMSI, P-TMSI signature, IMEI (International Mobile Equipment
Identity), MSISDN, RA, CI, Kc, CKSN, encryption algorithm, PDP information, etc.
The mobile management protocol is composed of three parts. They are the LLC and RLC / MAC protocols adopted by the Um interface, the MAP protocol adopted between the SGSN and HLR (Gr), the SGSN and EIR (Gf), the SGSN and MSC / VLR Gs) between BSSAP + agreement.
The following highlights the activation process and location management process in MM.
(1) Activation process â‘ The MS sends an activation request message to the new SGSN, which includes P-TMSI + old RAI (used when no P-TMSI is available)
IMSI), CKSN, activation type (only one of GPRS activated, GPRS activated when IMSI has been activated, GPRS / IMSI joint activation), DRX parameters, old P-TMSI signature.
② The new SGSN sends an identity authentication request message (P-TMSI, old RAI, old P-TMSI signature) to the old SGSN to obtain the MS ’s
IMSI. The old SGSN sends back an authentication response message (IMSI, three-parameter group for authentication). If the old SGSN cannot authenticate the MS, the corresponding cause of error will be sent back.
â‘¢If neither the new nor the old SGSN can authenticate the MS, the new SGSN will send an authentication request message to the MS (authentication type = IMSI),
The MS sends back a response message (IMSI).
â‘£ Confidential authentication between MS, new SGSN and HLR.
⑤ Perform IMEI inspection between MS, new SGSN and EIR.
â‘¥If the SGSN number has been changed during the initial activation or re-activation (compared to the last time), the SGSN should notify the HLR. From new
SGSN sends location update message (SGSN number, SGSN address, IMSI) to HLR; HLR sends location elimination message to old SGSN
(IMSI, elimination type); old SGSN response (IMSI); HLR sends insert user data message (IMSI, GPRS user data) to the new SGSN; the new SGSN checks the legality of the MS in the new RA, if the MS is a locally restricted user and If activation in the new RA is not allowed, the new SGSN returns a response (IMSI, SGSN area restricted) to the HLR, refusing the activation request. If the activation is not allowed for other reasons, the response (IMSI, reason) is returned to the HLR. If the MS is legal, it will return an answer (IMSI); HLR
The SGSN sends back a location update response.
⑦If the activation type in point ①is the latter two (activate GPRS, GPRS / IMSI joint activation when IMSI is activated), when the Gs interface between SGSN and MSC / VLR exists, update the VLR. The VLR number is obtained from RA. The new SGSN sends a location update request message (new LAI, IMSI, SGSN number, location update type) to the new MSC / VLR; the new VLR sends the HLR
Request location update (IMSI, new VLR); HLR notifies old VLR to eliminate location information (IMSI); old VLR responds to HLR
(IMSI); HLR sends the insert user data message (IMSI, GSM user data) to the new MSC / VLR; the new VLR answers the HLR
(IMSI). At this time, the new MSC / VLR sends a location update acceptance response (VLRTMSI) to the new SGSN.
⑧ The new SGSN sends an activation accept message (P-TMSI, VLRTMSI, P-TMSI signature) to the MS.
⑨ The MS sends an activation complete message (P-TMSI, VLRTMSI) to the new SGSN.
â‘© The new SGSN sends a TMSI reallocation complete message (VLRTMSI) to the new MSC / VLR.
(2) Location management process
The MS compares the received CI and RAI with the stored CI and RAI, and if a difference is found, it needs to initiate a location update request.
When the MS is in the ready state, a cell update request is initiated when the CI changes. When the MS is in the waiting state, it can only initiate RA
Update request, and when the CI changes within the same RA, the update request cannot be initiated. RA update is divided into SGSN internal RA update and SGSN
There are two types of RA updates. Here is a more complicated update of RA between SGSNs.
â‘ MS requests RA update from the new SGSN (old RAI, old P-TMSI signature, update type).
â‘¡ The new SGSN sends a request to the old SGSN to obtain the MM and PDP information of the MS (old RAI, TLLI, old P-TMSI signature, new SGSN
Address), the old SGSN responds.
â‘¢ Conduct security and confidentiality verification between MS, new SGSN and HLR.
â‘£ The new SGSN informs the old SGSN that it is ready to receive the activated PDP information.
⑤ The old SGSN forwards the stuck packet units to the new SGSN.
â‘¥ The new SGSN sends a PDP update request (new SGSN address, TID (Tunnel Identifier), negotiated QoS) to the GGSN,
GGSN response (TID).
⑦ The new SGSN requests location updates from the HLR (SGSN number, SGSN address, IMSI).
⑧ The HLR informs the old SGSN of the cancellation location (IMSI, cancellation type) and the old SGSN responds (IMSI).
⑨ The HLR sends an insert user data message (IMSI, GPRS user data) to the new SGSN, and the new SGSN responds (IMSI).
â‘© HLR responds to the location update request of the new SGSN (IMSI).
The new SGSN sends an RA update acceptance message (P-TMSI, P-TMSI signature, received N-PDU number) to the MS.
The MS sends the RA update complete message (P-TMSI, received N-PDU number) to the new SGSN.
4 Conclusion
GPRS is an advanced service capable of providing high-speed data, and its operation and implementation will take a big step towards the third-generation mobile communication that provides multimedia services. The position of the MS in mobile communication is always changing frequently, which in turn affects the management of users, the allocation of wireless resources, the establishment of communication connections, etc. Therefore, mobility management (MM) is a crucial issue to study mobile in GPRS Sexual management is far-reaching.
The planning of IP addresses in the GPRS network In the GPRS backbone network, the IP protocol is used at the network layer, and each SGSN and GGSN has an internal IP address for communication within the backbone network. When each GPRS terminal is connected to an external data network, such as an IP network, a corresponding IP address is required. Therefore,
The IP address is an important resource of the GPRS network, which is used for the identification of network equipment and users. Good address planning is very important for the development and maintenance of the network.
The IP address of the GPRS network can be divided into two cases: the address of the internal GPRS backbone network and the address required to connect to the Internet.
The first type is used for SGSN, GGSN, BG, DNS, DHCP, CG, network management equipment, all routers and WAP gateways used, and can use the reserved address specified in the RFCl597 file.
The reserved address is divided into three segments:
10.0.0.0 --- 10.255.255.255 (1 class A address);
172.16.0.0 --- 172.31.255.255 (16 connected Class B addresses);
192.168.0.0 --- 192.168.255.255 (256 connected Class C addresses).
The second type of address is a public IP address. These addresses are required for interconnection with the Internet. If the operator connects the GPRS network only to the Internet as a bearer network, the public IP is provided by IAP; if the operator also provides services as an ISP,
You need to apply to CNNICC for a public IP address.
The general address allocation principles are as follows:
a. The allocated addresses should meet the needs as soon as possible, and make the addresses as continuous as possible to reduce the size of the routing table.
b. Addresses need to be managed in a unified manner, allocated on demand and ensure effective use. The number of allocated addresses is allocated according to the principle that the utilization rate of the IP address of the application system reaches 25% in the initial stage and more than 50% in one year.
c. Network equipment (routers and GGSN) must support classless inter-domain routing technology (CIDR, Class Inter Domain)
Routing) and variable length subnet mask (VLSM, Variable Length Subnet Mask) technology, less than the number of network hosts
127 is generally assigned by subnet address, and the subnet mask is determined according to the actual number of hosts in the application system.
GPRS abbreviation
A
AA-Anonymous access
APN-Access point name
ARP-Address Resolution Protocol
ARQ-Automatic request resend
ATM-asynchronous transfer mode
AuC-Authentication Center
B
BB-backbone network carrying circuit
BCCH-Broadcast Control Channel
BCF-Base station control function
BCS-block check sequence
BEC-backward error correction
BG-Border Gateway
BS-billing system
BSC-Base Station Controller
BSS-Base Station Subsystem
BSSGP-GPRS Base Station Subsystem Agreement
BTS-Base Transceiver
BVC-BSSGP virtual connection
BVCI-BSSGP virtual connection identification
C
CG-billing gateway
CGF-billing gateway function
CGI-Community Global Identification
CI-cell identity
CLNP-connectionless network protocol
CLNS-connectionless network service
CMIP-General Management Information Protocol
CONS-connection-oriented network protocol
CRC-cyclic redundancy code check
CS-circuit switching, coding scheme
CU-cell upgrade
D
DB-Database
DL-downlink
DLCI-Data link connection identification
DNIC-Data Network Identification Code
DNS-Domain Name System
E
EIR-device identification register
ETSI-European Telecommunications Standards Committee
F
F / W-Firewall
FH-frame header
FTP-File Transfer Protocol
G
GGSN-gateway GPRS support node
GMSC-Gateway MSC
GPRS-General Packet Radio Service
GRE-General routing package
GSM-Global Mobile Communication System
GSN-GPRS support node
GTP-GPRS tunnel protocol
I
IMEI-International Mobile Equipment Identifier
IMSI-International Mobile User Identifier
IP-Internet protocol
IPv4-Internet Protocol version 4
IPv6-Internet Protocol version 6
ISP-Internet service provider
L
LAC-location area code
LAN-Local Area Network
LLC-Logical Link Control
LLM-logical link management
LLME-Logical Link Management Entity
M
MAC-Media Access Control
MCC-mobile service country code
MNC-Mobile network code
MO-Mobile calling
MS-Mobile Station
MSC-Mobile Switching Center
MT-mobile terminal
MTP2-message layer 2
MTP3-Message Transport Layer 3
N
NE-Network Unit
NFS-Network File System
NGAF-non-GPRS warning sign
NMG-Network Management Gateway
NMN-Network Management Node
N-PDU-Network Protocol Data Unit
NSE-Network Business Entity
NSS-network switching subsystem
O
OMC-Operation and Maintenance Center
OSF-operating system function
OSI-Open System Interconnection
P
PACCH-packet combination control channel
PAGCH-packet access confirmation channel
PBCCH- packet broadcast control control channel
PC-power control
PCCCH-packet shared control channel
PCU-group control unit
PDC-packet data communication
PDCH-packet data channel
PDN-packet data network
PDP-Packet Data Agreement
PDTCH-packet data traffic channel
PDU-protocol data unit
PL-Physical Link
PPP-point-to-point protocol
PSDN-Packet Exchange Database
PSPDN-packet switched public data network
PSTN-Public Switched Telephone Network
PTM SC-point-to-multipoint service center
PTM-point to multipoint
PTM-G-point-to-point-group call
PTM-M-point-to-multipoint-broadcast
P-TMSI-packet TMSI
PTP-point-to-point
PVC-permanent virtual circuit
Q
QoS-quality of service
R
RLC-Wireless Link Control
S
SAP-Service Access Point
SC-Business Center
SDU-Service Data Unit
SGSN-service GPRS support node
SIM-User ID Card
SMS-short message service
SM-SC-Short Message-Business Center
SMSS-Exchange and Management Subsystem
SNDC-Subnet Independent Convergence
SNDCP-Subnet Independent Convergence Protocol
SS # 7-7 signaling system
SVC-switched virtual circuit
T
TA-Pre-timing
TCP-Transmission Control Protocol
TDMA-time division multiple access
TEPI-Tunnel Endpoint Identification
Tunnel endpoint identification in TEPIG-GGSN
Tunnel endpoint identification in TEPIS-SGSN
TID-Tunnel Identification
TLLI-Temporary logical link identification
TRAU-transcoder and rate adaptation unit
TRX-Transmitter-Receiver
U
UDP-User Datagram Protocol
UL-uplink
V
VPN-Virtual Private Network
Vacuum Cleaner Ac Dry-Wet Motor
Vacuum Cleaner Ac Dry-Wet Motor,Vacuum Electric Cleaner Ac Motor,Wet Dry Vacuum Cleaner Motor,Wet And Dry Vacuum Cleaner Motor
Zhoushan Chenguang Electric Appliance Co., Ltd. , https://www.vacuum-cleaner-motors.com