The GPRS amount arrangement is the axial allotment of the General Packet Radio Service which allows 2G, 3G and WCDMA adaptable networks to address IP packets to alien networks such as the Internet. The GPRS arrangement is an chip allotment of the GSM arrangement switching subsystem.
Friday, February 24, 2012
General support functions
The GPRS amount arrangement provides advancement management, affair administration and carriage for Internet Protocol packet casework in GSM and WCDMA networks. The amount arrangement aswell provides abutment for added added functions such as announcement and allowable interception. It was aswell proposed, at one stage, to abutment packet radio casework in the US D-AMPS TDMA system, however, in practice, all of these networks accept been adapted to GSM so this advantage has become irrelevant.
Like GSM in general, GPRS bore is an accessible standards apprenticed system. The acclimation physique is the 3GPP.
Like GSM in general, GPRS bore is an accessible standards apprenticed system. The acclimation physique is the 3GPP.
GPRS tunnelling protocol (GTP)
GPRS tunnelling agreement is the defining IP-based agreement of the GPRS amount network. Primarily it is the agreement which allows end users of a GSM or WCDMA arrangement to move from abode to abode while continuing to affix to the Internet as if from one area at the Gateway GPRS Support Node (GGSN). It does this by accustomed the subscriber's abstracts from the subscriber's accepted Serving GPRS Support Node (SGSN) to the GGSN which is administration the subscriber's session. Three forms of GTP are acclimated by the GPRS amount network.
GTP-U
for alteration of user abstracts in afar tunnels for anniversary Packet Abstracts Agreement (PDP) context
GTP-C
for ascendancy affidavit including:
bureaucracy and abatement of PDP contexts
analysis of GSN reachability
updates; e.g., as subscribers move from one SGSN to another.
GTP'
for alteration of charging abstracts from GSNs to the charging function.
GGSNs and SGSNs (collectively accepted as GSNs) accept for GTP-C letters on UDP anchorage 2123 and for GTP-U letters on anchorage 2152. This advice is absolute aural a individual network, or in the case of all-embracing roaming, via a GPRS adrift barter (GRX).
The Charging Gateway Action (CGF) listens to GTP' letters beatific from the GSNs on TCP or UDP anchorage 3386. The amount arrangement sends charging advice to the CGF, about including PDP ambience activation times and the abundance of abstracts which the end user has transferred. However, this advice which occurs aural one arrangement is beneath connected and may, depending on the bell-ringer and agreement options, use proprietary encoding or even an absolutely proprietary system.
GTP adaptation aught supports both signalling and user abstracts beneath one all-encompassing header. It can be acclimated with UDP (User Datagram Protocol) or TCP (Transmission Ascendancy Protocol) on the registered anchorage 3386. GTP adaptation one is acclimated alone on UDP. The ascendancy even agreement GTP-C (Control) application registered anchorage 2123 and the user even agreement GTP-U (User) application registered anchorage 2152.
GTP-U
for alteration of user abstracts in afar tunnels for anniversary Packet Abstracts Agreement (PDP) context
GTP-C
for ascendancy affidavit including:
bureaucracy and abatement of PDP contexts
analysis of GSN reachability
updates; e.g., as subscribers move from one SGSN to another.
GTP'
for alteration of charging abstracts from GSNs to the charging function.
GGSNs and SGSNs (collectively accepted as GSNs) accept for GTP-C letters on UDP anchorage 2123 and for GTP-U letters on anchorage 2152. This advice is absolute aural a individual network, or in the case of all-embracing roaming, via a GPRS adrift barter (GRX).
The Charging Gateway Action (CGF) listens to GTP' letters beatific from the GSNs on TCP or UDP anchorage 3386. The amount arrangement sends charging advice to the CGF, about including PDP ambience activation times and the abundance of abstracts which the end user has transferred. However, this advice which occurs aural one arrangement is beneath connected and may, depending on the bell-ringer and agreement options, use proprietary encoding or even an absolutely proprietary system.
GTP adaptation aught supports both signalling and user abstracts beneath one all-encompassing header. It can be acclimated with UDP (User Datagram Protocol) or TCP (Transmission Ascendancy Protocol) on the registered anchorage 3386. GTP adaptation one is acclimated alone on UDP. The ascendancy even agreement GTP-C (Control) application registered anchorage 2123 and the user even agreement GTP-U (User) application registered anchorage 2152.
GPRS support nodes (GSN)
A GSN is a arrangement bulge which supports the use of GPRS in the GSM amount network. All GSNs should accept a Gn interface and abutment the GPRS tunneling protocol. There are two key variants of the GSN, namely Aperture and Confined GPRS Abutment Node.
edit Aperture GPRS Abutment Bulge (GGSN)
The Aperture GPRS Abutment Bulge (GGSN) is a capital basic of the GPRS network. The GGSN is amenable for the interworking amid the GPRS arrangement and alien packet switched networks, like the Internet and X.25 networks.
From an alien network's point of view, the GGSN is a router to a sub-network, because the GGSN ‘hides’ the GPRS basement from the alien network. When the GGSN receives abstracts addressed to a specific user, it checks if the user is active. If it is, the GGSN assiduously the abstracts to the SGSN confined the adaptable user, but if the adaptable user is inactive, the abstracts is discarded. On the added hand, mobile-originated packets are baffled to the adapted arrangement by the GGSN.
The GGSN is the ballast point that enables the advancement of the user terminal in the GPRS/UMTS networks. In essence, it carries out the role in GPRS agnate to the Home Agent in Adaptable IP. It maintains acquisition all-important to adit the Agreement Abstracts Units (PDUs) to the SGSN that casework a accurate MS (Mobile Station).
The GGSN converts the GPRS packets advancing from the SGSN into the adapted packet abstracts agreement (PDP) architecture (e.g., IP or X.25) and sends them out on the agnate packet abstracts network. In the added direction, PDP addresses of admission abstracts packets are adapted to the GSM abode of the destination user. The readdressed packets are beatific to the amenable SGSN. For this purpose, the GGSN food the accepted SGSN abode of the user and his or her contour in its breadth register. The GGSN is amenable for IP abode appointment and is the absence router for the affiliated user accessories (UE). The GGSN aswell performs affidavit and charging functions.
Other functions cover subscriber screening, IP Pool administration and abode mapping, QoS and PDP ambience enforcement.
With LTE book the GGSN functionality moves to SAE aperture (with SGSN functionality alive in MME).
edit Confined GPRS Abutment Bulge (SGSN)
A Confined GPRS Abutment Bulge (SGSN) is amenable for the supply of abstracts packets from and to the adaptable stations aural its bounded account area. Its tasks cover packet acquisition and transfer, advancement administration (attach/detach and breadth management), analytic hotlink management, and affidavit and charging functions. The breadth annals of the SGSN food breadth advice (e.g., accepted cell, accepted VLR) and user profiles (e.g., IMSI, address(es) acclimated in the packet abstracts network) of all GPRS users registered with this SGSN....
edit Common SGSN Functions
Detunnel GTP packets from the GGSN (downlink)
Adit IP packets against the GGSN (uplink)
Carry out advancement administration as Standby approach adaptable moves from one Acquisition Breadth to addition Acquisition Area
Billing user data
edit GSM/EDGE specific SGSN functions
Enhanced Abstracts Rates for GSM Evolution (EDGE) specific SGSN functions and characteristics are:
Maximum abstracts amount of approx. 60 kbit/s (150 kbit/s for EDGE) per subscriber
Connect via anatomy broadcast or IP to the Packet Control Unit application the Gb agreement stack
Accept uplink abstracts to anatomy IP packets
Encrypt down-link data, break up-link data
Carry out advancement administration to the akin of a corpuscle for affiliated approach mobiles
edit WCDMA specific SGSN functions
Carry up to about 42 Mbit/s cartage downlink and 5.8 Mbit/s cartage uplink (HSPA+)
Tunnel/detunnel downlink/uplink packets against the radio arrangement ambassador (RNC)
Carry out advancement administration to the akin of an RNC for affiliated approach mobiles
These differences in functionality accept led some manufacturers to actualize specialist SGSNs for anniversary of WCDMA and GSM which do not abutment the added networks, whilst added manufacturers accept succeeded in creating both together, but with a achievement amount due to the compromises required.
edit Aperture GPRS Abutment Bulge (GGSN)
The Aperture GPRS Abutment Bulge (GGSN) is a capital basic of the GPRS network. The GGSN is amenable for the interworking amid the GPRS arrangement and alien packet switched networks, like the Internet and X.25 networks.
From an alien network's point of view, the GGSN is a router to a sub-network, because the GGSN ‘hides’ the GPRS basement from the alien network. When the GGSN receives abstracts addressed to a specific user, it checks if the user is active. If it is, the GGSN assiduously the abstracts to the SGSN confined the adaptable user, but if the adaptable user is inactive, the abstracts is discarded. On the added hand, mobile-originated packets are baffled to the adapted arrangement by the GGSN.
The GGSN is the ballast point that enables the advancement of the user terminal in the GPRS/UMTS networks. In essence, it carries out the role in GPRS agnate to the Home Agent in Adaptable IP. It maintains acquisition all-important to adit the Agreement Abstracts Units (PDUs) to the SGSN that casework a accurate MS (Mobile Station).
The GGSN converts the GPRS packets advancing from the SGSN into the adapted packet abstracts agreement (PDP) architecture (e.g., IP or X.25) and sends them out on the agnate packet abstracts network. In the added direction, PDP addresses of admission abstracts packets are adapted to the GSM abode of the destination user. The readdressed packets are beatific to the amenable SGSN. For this purpose, the GGSN food the accepted SGSN abode of the user and his or her contour in its breadth register. The GGSN is amenable for IP abode appointment and is the absence router for the affiliated user accessories (UE). The GGSN aswell performs affidavit and charging functions.
Other functions cover subscriber screening, IP Pool administration and abode mapping, QoS and PDP ambience enforcement.
With LTE book the GGSN functionality moves to SAE aperture (with SGSN functionality alive in MME).
edit Confined GPRS Abutment Bulge (SGSN)
A Confined GPRS Abutment Bulge (SGSN) is amenable for the supply of abstracts packets from and to the adaptable stations aural its bounded account area. Its tasks cover packet acquisition and transfer, advancement administration (attach/detach and breadth management), analytic hotlink management, and affidavit and charging functions. The breadth annals of the SGSN food breadth advice (e.g., accepted cell, accepted VLR) and user profiles (e.g., IMSI, address(es) acclimated in the packet abstracts network) of all GPRS users registered with this SGSN....
edit Common SGSN Functions
Detunnel GTP packets from the GGSN (downlink)
Adit IP packets against the GGSN (uplink)
Carry out advancement administration as Standby approach adaptable moves from one Acquisition Breadth to addition Acquisition Area
Billing user data
edit GSM/EDGE specific SGSN functions
Enhanced Abstracts Rates for GSM Evolution (EDGE) specific SGSN functions and characteristics are:
Maximum abstracts amount of approx. 60 kbit/s (150 kbit/s for EDGE) per subscriber
Connect via anatomy broadcast or IP to the Packet Control Unit application the Gb agreement stack
Accept uplink abstracts to anatomy IP packets
Encrypt down-link data, break up-link data
Carry out advancement administration to the akin of a corpuscle for affiliated approach mobiles
edit WCDMA specific SGSN functions
Carry up to about 42 Mbit/s cartage downlink and 5.8 Mbit/s cartage uplink (HSPA+)
Tunnel/detunnel downlink/uplink packets against the radio arrangement ambassador (RNC)
Carry out advancement administration to the akin of an RNC for affiliated approach mobiles
These differences in functionality accept led some manufacturers to actualize specialist SGSNs for anniversary of WCDMA and GSM which do not abutment the added networks, whilst added manufacturers accept succeeded in creating both together, but with a achievement amount due to the compromises required.
Access point
Main article: Admission point name
An admission point is:
An IP arrangement to which a adaptable can be connected
A set of settings which are acclimated for that connection
A accurate advantage in a set of settings in a adaptable phone
When a GPRS adaptable buzz sets up a PDP context, the admission point is selected. At this point an admission point name (APN) is determined
Example: aricenttechnologies.mnc012.mcc345.gprs
Example: Internet
Example: mywap
Example: hcl.cisco.ggsn
This admission point is again acclimated in a DNS concern to a clandestine DNS network. This action (called APN resolution) assuredly gives the IP abode of the GGSN which should serve the admission point. At this point a PDP ambience can be activated.
An admission point is:
An IP arrangement to which a adaptable can be connected
A set of settings which are acclimated for that connection
A accurate advantage in a set of settings in a adaptable phone
When a GPRS adaptable buzz sets up a PDP context, the admission point is selected. At this point an admission point name (APN) is determined
Example: aricenttechnologies.mnc012.mcc345.gprs
Example: Internet
Example: mywap
Example: hcl.cisco.ggsn
This admission point is again acclimated in a DNS concern to a clandestine DNS network. This action (called APN resolution) assuredly gives the IP abode of the GGSN which should serve the admission point. At this point a PDP ambience can be activated.
PDP Context
The packet abstracts agreement (PDP; e.g., IP, X.25, FrameRelay) ambience is a abstracts anatomy present on both the Confined GPRS Support Node (SGSN) and the Gateway GPRS Support Node (GGSN) which contains the subscriber's affair advice if the subscriber has an alive session. If a adaptable wants to use GPRS, it accept to aboriginal attach and again actuate a PDP context. This allocates a PDP ambience abstracts anatomy in the SGSN that the subscriber is currently visiting and the GGSN confined the subscriber's admission point. The abstracts recorded includes
Subscriber's IP address
Subscriber's IMSI
Subscriber's
Tunnel Endpoint ID (TEID) at the GGSN
Tunnel Endpoint ID (TEID) at the SGSN
The Tunnel Endpoint ID (TEID) is a amount allocated by the GSN which identifies the tunnelled abstracts accompanying to a accurate PDP context.
Several PDP contexts may use the aforementioned IP address. The Accessory PDP Ambience Activation action may be acclimated to actuate a PDP ambience while reusing the PDP abode and added PDP ambience advice from an already alive PDP context, but with a altered QoS profile.1 Note that the action is alleged secondary, not the consistent PDP contexts that accept no such accord with the one the PDP abode of which they reused.
A absolute of 11 PDP contexts (with any aggregate of primary and secondary) can co-exist. NSAPI are acclimated to differentiate the altered PDP context.
Subscriber's IP address
Subscriber's IMSI
Subscriber's
Tunnel Endpoint ID (TEID) at the GGSN
Tunnel Endpoint ID (TEID) at the SGSN
The Tunnel Endpoint ID (TEID) is a amount allocated by the GSN which identifies the tunnelled abstracts accompanying to a accurate PDP context.
Several PDP contexts may use the aforementioned IP address. The Accessory PDP Ambience Activation action may be acclimated to actuate a PDP ambience while reusing the PDP abode and added PDP ambience advice from an already alive PDP context, but with a altered QoS profile.1 Note that the action is alleged secondary, not the consistent PDP contexts that accept no such accord with the one the PDP abode of which they reused.
A absolute of 11 PDP contexts (with any aggregate of primary and secondary) can co-exist. NSAPI are acclimated to differentiate the altered PDP context.
Reference points and interfaces
Within the GPRS amount arrangement standards there are a amount of interfaces and advertence credibility (logical credibility of affiliation which apparently allotment a accepted concrete affiliation with added advertence points). Some of these names can be apparent in the arrangement anatomy diagram on this page.
Reference points and interfaces
Within the GPRS amount arrangement standards there are a amount of interfaces and advertence credibility (logical credibility of affiliation which apparently allotment a accepted concrete affiliation with added advertence points). Some of these names can be apparent in the arrangement anatomy diagram on this page.
edit Interfaces in the GPRS network
Ga
The interface serves the CDRs (accounting records) which are accounting in the GSN and beatific to the charging aperture (CG). This interface uses a GTP-based protocol, with modifications that supports CDRs (Called GTP' or GTP prime).
Gb
Interface amid the abject base subsystem and the SGSN the manual agreement could be Frame Relay or IP.
Gd
Interface amid the SGSN and the SMS Gateway. Can use MAP1, MAP2 or MAP3.
Ge
The interface amid the SGSN and the account ascendancy point (SCP); uses the CAP protocol.
Gf
The interface amid the SGSN and the Accessories Character Register (EIR), acclimated for blockage the mobile's accessories character amount (IMEI) adjoin a account of appear baseborn adaptable phones.
Gi
IP based interface amid the GGSN and a accessible abstracts arrangement (PDN) either anon to the Internet or through a WAP gateway.
Gmb
The interface amid the GGSN and the Broadcast-Multicast Account Center (BM-SC), acclimated for authoritative MBMS bearers.
Gn
IP Based interface amid SGSN and added SGSNs and (internal) GGSNs. DNS aswell shares this interface. Uses the GTP Protocol.
Gp
IP based interface amid centralized SGSN and alien GGSNs. Amid the SGSN and the alien GGSN, there is the bound aperture (which is about a firewall). Aswell uses the GTP Protocol.
Gr
Interface amid the SGSN and the HLR. Messages traveling through this interface uses the MAP3 protocol.
Gs
Interface amid the SGSN and the MSC (VLR). Uses the BSSAP+ protocol. This interface allows paging and base availability if it performs abstracts transfer. If the base is absorbed to the GPRS network, the SGSN keeps clue of which acquisition breadth (RA) the base is absorbed to. An RA is a allotment of a beyond breadth breadth (LA). If a base is paged this advice is acclimated to conserve arrangement resources. If the base performs a PDP context, the SGSN has the exact BTS the base is using.
Gx
The off-line action interface amid the GGSN and the charging rules action (CRF). It is acclimated for accessories account abstracts breeze based on charging rules. Uses the bore protocol.
Gy
The on-line charging interface amid the GGSN and the online charging arrangement (OCS). Uses the bore agreement (DCCA application).
Gz
The off-line (CDR-based) charging interface amid the GSN and the CG. Uses GTP'.
Lg
The interface amid the SGSN and the Aperture Adaptable Breadth Center (GMLC), acclimated for breadth based services.
edit Interfaces in the GPRS network
Ga
The interface serves the CDRs (accounting records) which are accounting in the GSN and beatific to the charging aperture (CG). This interface uses a GTP-based protocol, with modifications that supports CDRs (Called GTP' or GTP prime).
Gb
Interface amid the abject base subsystem and the SGSN the manual agreement could be Frame Relay or IP.
Gd
Interface amid the SGSN and the SMS Gateway. Can use MAP1, MAP2 or MAP3.
Ge
The interface amid the SGSN and the account ascendancy point (SCP); uses the CAP protocol.
Gf
The interface amid the SGSN and the Accessories Character Register (EIR), acclimated for blockage the mobile's accessories character amount (IMEI) adjoin a account of appear baseborn adaptable phones.
Gi
IP based interface amid the GGSN and a accessible abstracts arrangement (PDN) either anon to the Internet or through a WAP gateway.
Gmb
The interface amid the GGSN and the Broadcast-Multicast Account Center (BM-SC), acclimated for authoritative MBMS bearers.
Gn
IP Based interface amid SGSN and added SGSNs and (internal) GGSNs. DNS aswell shares this interface. Uses the GTP Protocol.
Gp
IP based interface amid centralized SGSN and alien GGSNs. Amid the SGSN and the alien GGSN, there is the bound aperture (which is about a firewall). Aswell uses the GTP Protocol.
Gr
Interface amid the SGSN and the HLR. Messages traveling through this interface uses the MAP3 protocol.
Gs
Interface amid the SGSN and the MSC (VLR). Uses the BSSAP+ protocol. This interface allows paging and base availability if it performs abstracts transfer. If the base is absorbed to the GPRS network, the SGSN keeps clue of which acquisition breadth (RA) the base is absorbed to. An RA is a allotment of a beyond breadth breadth (LA). If a base is paged this advice is acclimated to conserve arrangement resources. If the base performs a PDP context, the SGSN has the exact BTS the base is using.
Gx
The off-line action interface amid the GGSN and the charging rules action (CRF). It is acclimated for accessories account abstracts breeze based on charging rules. Uses the bore protocol.
Gy
The on-line charging interface amid the GGSN and the online charging arrangement (OCS). Uses the bore agreement (DCCA application).
Gz
The off-line (CDR-based) charging interface amid the GSN and the CG. Uses GTP'.
Lg
The interface amid the SGSN and the Aperture Adaptable Breadth Center (GMLC), acclimated for breadth based services.
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