2G/2.5G/3GArchitectureManu Mittal

2G to 3G Roadmap

2G

GSM Architecture

Network ElementsHLREvery PLMN requires access to at least one HLR as a permanent store of dataCan best be regarded as a large database with access times that must be kept as short as possible (for faster connectivity)Maintains subscriber information on teleservices and bearer services subscription, service restrictions, and supplementary servicesEach subscriber is assigned to one specific HLR, which acts as a fixed reference point and where information on the current location of the user is storedAuCAlways implemented as an integral part of the HLRThe reason for this is that although GSM mentions the interface between the AuC and the HLR and has even assigned it a name, the H-interface, it was never specified in sufficient detail to be a standalone entityContains a copy of the secret key (Ki) stored in the SIMCalculates and provides the authentication-triplets, that is, the signed response (SRES), the random number (RAND), and KcVLR uses these as input parameters for authentication and cipheringData Chart

Network ElementsVLRProvides dynamic subscriber data managementAs the subscriber moves from an old VLR to a new VLR, relevant data is also transferred (additional data could be requested from the HLR)The permanent data is the same as data in the HLRThe temporary data includesTemporary Subscriber Identity (TMSI)Location Area Identity (LAI) of an MHVLR allocates mobile subscriber roaming numbers (MSRNs) for the incoming call setupTypically, a VLR is linked with a single MSCEIRContains a list of all valid mobile equipment on the network, where each mobile station is identified by its International Mobile Equipment Identity (IMEI)

Data Chart

Network ElementsBase Station Controller (BSC):Maintains radio connections towards Mobile StationMaintains terrestrial connection towards the NSSBase Transceiver Station (BTS):Air interface signalling, ciphering and speech processingMobile Service Switching Centre (MSC):Call controlBSS control functionsInternetworking functionsChargingStatisticsInterface signalling towards BSS and external networks

Serving MSC: BSS connections, mobility management, inter-workingGateway MSC: Connections to the other networks

GSM Protocol ArchitectureMSBTSMSCBSCUm InterfaceA-bis interfaceA interfaceLayer 3Layer 2Layer 1CMMMRRRRMMCMRRLAPDmLAPDmLAPDLAPDPhysical layerPhysical layerPhysical layerPhysical layerBTSMBTSMBSSAPBSSAPSCCPSCCPMTPMTP

2G2.5G

GPRS Architecture

GPRS Architecture - ComponentsNew components introduced for GPRS services:PCU (Packet Control Unit)SGSN (Serving GPRS Support Node)GGSN (Gateway GPRS Support Node)IP-based backbone network

Old components in GSM upgraded for GPRS services:HLRMSC/VLRMobile Station

Modified Elements:BSS Introduction of packet control functionality (PCU) within the BSS to provide interface between packets and GSM air interface

MSCMSC requires changes to support inter-working to the new packet network node SGSN

Gs interface plays a key role, be it synchronization of Paging or combines CS/PS location updates

HLRHLR requires changes to support GPRS subscriber, feature, and mobility management data for GPRS Mobile Subscribers

PCU (Packet Control Unit)Converts packet data information into a format that can be transferred over the air interface

Manages radio resources

Implements Quality of service (QoS) measurement

SGSN (Serving GPRS support node)At the same hierarchical level as the MSC

Transfers data packets between mobile stations and GGSNs

Keeps track of the individual MSs location and performs security functions and access control

Detects and registers new GPRS mobile stations located in its service area

Participates into routing, as well as mobility management functions

GGSN (Gateway GPRS support node)It is the gateway in and out of the GPRS system

Functions:

Converts the GPRS packets from SGSN into the appropriate packet data protocol format (e.g., IP or X.25) and sends out on the corresponding packet data network

Packet routing and transmission

Access Control

Maintains the location information of the mobile stations that are using the data protocols provided by that GGSN.

Collects charging information for billing purpose

IP BackboneProtocol architecture based on the Internet Protocol (IP)

GTP (GPRS Tunneling Protocol) used to tunnel user data and signaling between GPRS Support Nodes. All PDP (Packet Data Protocol) PDUs (Protocol Data Units) shall be encapsulated by GTP

Two kinds of GPRS backbone Network:Intra-PLMN backbone network: The IP network interconnecting GSNs within the same PLMN.Inter-PLMN backbone network: The IP network interconnecting GSNs and intra-PLMN backbone networks in different PLMNs.

Two intra-PLMN backbone networks are connected via the Gp interface using Border Gateways and an inter-PLMN backbone network.

Border Gateway handles the packet transfer between GPRS PLMNs.

Communication between GPRS station and IP Host

GSM/GPRS Protocol Stack Architecture

Transmission plane MS-GGSN

Signaling plane MS-SGSN

2G2.5G3G

UMTS Network ArchitectureA typical UMTS network can be modeled as comprising of three basic parts:

User Equipment (UE) Access Network (AN) Core Network (CN)

UMTS Network Architecture ChangesMost of the change is in the Radio Access Network (RAN) part of the mobile network

CN network elements in 3G are upgraded versions of their 2G counterparts

Radio Access Scheme in 3G is different from that used in GSM/GPRS - WCDMA

Change in Radio Access Scheme allows operators to support multimedia services

What are NAS and AS?AS provides means to carry information over the air interface and the means to manage its resourcesNAS includes protocols that apply between UE and CN

Access NetworkAnalogy between 2G and 3G AS architecture could be derived as:

RNC replaces the BSCNode-B replaces the BTSRadio Access Technology changes to WCDMA

UMTS Terrestrial Radio Access Network (UTRAN)Hierarchical structureA Radio Network Controller (RNC) and associated Node-Bs form a Radio Network Sub-system (RNS)A Node-B is connected to a single RNC but an RNC is connected to multiple Node-BsA new interface Iur introduced for macro diversity

Interface Location Equivalent in GSM UuUE UTRANUmIuUTRAN CNIu-CS: RNC MSCAIu-PS: RNC SGSNGbIurRNC RNCNoneIubNode B RNCAbis

UTRAN: Functions of Node-BConnects with UE on Uu interface and RNC on Iub

Conversion of data to and from Uu interface

Forward Error Correction, Rate adaptation, Spreading/De-spreading

Channel Coding

Measurement report to RNC, handover etc.

Inner loop Power control

UTRAN: Functions of RNCRadio resource control & Channel allocation Mobile Station Admission and Traffic load/congestion control Power control settingsOuter loop power control Handover control Ciphering Channelization and scrambling code allocation handling Segmentation and reassembly Data transmission scheduling in packet transfer mode Broadcast signaling Combining/distribution of signals from/to different node Bs in a macro diversity situation

Core NetworkExisting CN components used in GSM are still used - MSC, VLR, HLR, SGSN, GGSN etc.

UMTS Protocol Architecture: Radio Interface Protocols (Control plane & User plane)These include: Medium Access Control (MAC) Radio Link Control (RLC) Broadcast/Multicast Control (BMC) Packet Data Convergence Protocol (PDCP) Radio Resource Control (RRC)

Layer 3Layer 2

UMTS Protocol Architecture: Radio Network Protocols (Control plane & User plane)Radio Access Network Application Part (RANAP)Controls signaling between Access & Core NetworkControls signaling for both Iu_CS and Iu_PS interfaces have the same control planeEquivalent in functionality to its GSM counterpart - BSSMAP (BSS Management Application Part) and GPRS counterpart BSSGP (BSS GPRS Protocol)

Radio Network Subsystem Application Part (RNSAP)Controls the signaling between two RNC over Iur interface

Node B Application Part (NBAP)Controls signaling between RNC and Node B over Iub interface

Iu User Plane Protocol

Iu Framing Protocol

Control Plane ProtocolsUser Plane Protocols

Iu Interface ProtocolsIu-CSIu-PSCS networkSS7 Evolution

Iur & Iub InterfacesIurIubCS networkSS7 Evolution

Thank You!

CS core NetworkControl PlaneUser Plane

SS7 Signaling Evolution

Important data in HLR & VLR

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