GPRS,EDGE and UMTS positioning over 2G till 3G period.
GPRS technology introduce few network elements and nodes to the existing PLMN (phase 2) network which had been welly serving the circuit switch barrier services which are voice and short message service.
SGSN,GGSN in GPRS networks- PCU (Packet Control Unit)
- SGSN (Serving GPRS Support Node)
- GGSN (Gateway GPRS Support Node)
- BG (Border Gateway)
New Interface that introduced in GPRS service- Gb (Interface between PCU and SGSN)
- Gd (Interface between SGSN and SMS-Gateway MSC (SMS-GMSC))
- Gf (Interface between SGSN and EIR for enquired IMEI)
- Gn (Interface between SGSN and local PLMN)
- Gp (Interface between SGSN and other PLMN when roaming - inbound roaming)
- Gs (Interface between SGSN and VLR for cordinating conventional GSM network when operating in GSM mode and GPRS Mode) - backward compatible
- Gr (Interface between SGSN and HLR for exchange subscriber information)
- Gc(Interface between GGSN and HLR for exchange location information)
- Gi (Interface between GGSN with external packet network element or service provider)
p/s: Gc and Gs is an optional implementation)
PCU - Packet Control Unit
- It can be located at SGSN, BSC or at BTS side depending on the vendor that implementing it.
- Conversion of Packet Data into PCU-Frames ( packet switched data and also TRAU-Frame from circuit switch data). PCU route both traffic types, circuit-switched and packet switched for all downstream. While upstream, PCU fraems converted and sent to SGSN via frame relay / ATM networks.
- Responsible for all radio control in GPRS which is Radio Link Control and Medium Access Control.
SGSN - Serving GPRS Support Node- Routing of data packets between GGSN and packet switched service.
- Mobility management that update the HLR via GPRSLocationUpdate operations whenever there is changes of Routing Area ( smaller than Location Area in conventional GSM 2G network). Besides, the SGSN will also inter operate with VLR via BSSMAP+ to update location area if there is changes compare to the previous location area.
- PDP / GPRS Session Management for maintaining the Packet Data Protocol session
- Resolve the APN ( Access Point Name ) via DNS liked service to indentify which GGSN should it to refer to. GTP (GPRS Tunnel Protocol is used for the SGSN and GGSN communications)
- SGSN would need to have huge tempory buffer of the packet data in case there is changes of cell during packet data transfer, the earlier SGSN would need to transfer the unacknowledged packet to the newly roam SGSN.
- Data compression also be part of the SGSN role to optimized the air-interface transferring of bursty traffic.
- Domestic charging can be applied here.
GGSN (Gateway GPRS Support Node)
- Interconnection of the PLMN network towards external packet data network service provider.
- If Internet Protocol is chosen as the PDP context, the mapping of IP address that obtain during the session management and the mobile station identification will be kept here.
- International GPRS roaming charging can be applied here as the SGSN can be a foreign PLMN.
BG (Border Gateway)- takes care of all inter-PLMN GPRS traffic. It is important for roaming mobile stations.
Class A,B and C GPRS mobile station- Class A - Simultaneous Operation of Circuit Switch and Packet Switch (both operate at the same time)
- Class B - Simultaneous Monitoring only, if the Packet Switch is active ( e.g. surfing WAP ) there is a traffic activity on Circuit Switch ( e.g. SMS ) the Packet Switch GPRS session will be suspend and resume after the circuit switch activity finish.
- Class C - Only support Circuit Switch or Packet Switch network only.
In next article more topic on GPRS mobile management with backward compatible with conventional GSM network will be discussed.
Telecom convergence had became a very popular and common words in telecoms industry. Service providers, vendors and standardization body had always coming out with various suggestion and solution to reduce the CAPEX ( capital expenditure) and also OPEX ( operational expenditure ) . Telecoms technology continuously changing and evolving everyday in the area of transport approach (TDM, VoIP) , protocol handshake (H.323, IS41, MAP, SIP) and etc.Why Silo based deployment model exist?
3 separate silo application of different type of network
There is various type of telecoms network exist in current telecom eco-systems such as wireline network, wireless network (GSM, CDMA) and IP Network ( IMS, NGN ). Each of them having thier own predefine protocol hand-shake and transportation medium, thus each service creation or application deployment consist of the detail network protocol handling to ensure the functionality of the service across the network. No doubts, the cost of maintaining various service creation and application will be increase and become expensive when come to customization The result of the silo based deployment will increase the operators or service providers CAPEX and OPEX .Towards Application and Service Converged ( Parlay or ASC )?When Telecoms meet IT, this is where the convergence come in and few infrastructure concept had been adopted such as SDP ( Server Delivery Platform ) and IMS ( IP Multimedia Subsystems ). The emerge of SDP is to cut down the complexity of service creation and application to various type of network by providing the network abstraction without knowing the details of the core networks flow and functionality.
Parlay Gateway in the position of Service Delivery Platform
Parlay / Parlay X gateway came in to serve the central point of network resource management as well as network abstraction to the service creation and application that deployed in the SDP systems. The maturity of the Parlay Gateway deployment is still on the evaluation by the community. On the other hands, some may think that the deployment of Parlay Gateway will incurre another silo and add on CAPEX at the network layer. Another party may think Parlay Gateway doesn't address the legacy IN ( Intelligent Network) application. ASC as the ultimate solutions?
AppTrigger Application Session Controller for the support of legacy network
AppTrigger, a telecoms solution company had come out the idea of Application Session Controller (ASC). The ASC will be sitting in the middle of application and the core network layer by providing a unified data session controller across various network e.g. TCAP ( wireless network), SIP ( IP-Network ) and INAP ( wired line network ) as well as other legacy network.Similarity and ConclusionBoth Parlay and ASC serve the similarly which to provide the network abstraction to the applications and services creation. In order to converge various network systems would need some time and redefine the standard API, besides the practicality and business use case would also need to be considered.
One things for sure for telecoms service provider and vendor would need to find their way to maintain single service creations logic e.g. (Location Base Services as well as Caller RingTone) regardless GSM networks, IMS based SIP network or fix line network.
Thus a unified session application handshake protocol would be needed and network specific enabler (plugin model) need to exist to achieve the real convergence environment.
resources and link:-AppTrigger Application Session Controller
App Trigger 1st IN based systems intergrate with IMS implementation
Parlay Group
GPRS,EDGE and UMTS positioning over 2G till 3G period
