0WB080003(slide)SGSN9810 V800 (UAG)Hardware System-20090228-B-V2.0
Railway Operational Communication Solution GSM-R SGSN9810 Product Description1.0(20090330)
description
Transcript of Railway Operational Communication Solution GSM-R SGSN9810 Product Description1.0(20090330)
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Product Description
GSM-R SGSN9810 Product Description
Issue V1.0
Date 2009-03-30
HUAWEI TECHNOLOGIES CO., LTD.
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Huawei Technologies Co., Ltd. provides customers with comprehensive technical support and service.
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About This Document
Author
Prepared by Liao Huanran Date 2009-03-30
Reviewed by Date
Approved by Wang Zhoujie Date 2009-03-30
Summary This document provides information for the product function, features, technical indexes, and
structure of the SGSN9810 serving GPRS support node so that you can have a global view of
the SGSN9810.
This document includes:
Chapter Details
1 Overview Describes the position and application of the SGSN9810 in
a network.
2 Product Feature Describes the product features of the SGSN9810.
3 System Structure Describes the hardware, software, and logical structure of
the SGSN9810.
4 Function Describes the product features of the SGSN9810.
5 Operation and
Maintenance
Describes the operation and maintenance of the
SGSN9810.
6 Reliability Describes the hardware and software reliability of the
SGSN9810.
7 Technical Index Describes the technical indexes of the SGSN9810.
8 Installation Describes the fundamental features for the hardware and
software installation of the SGSN9810.
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History
Issue Details Date Author Approved by
V1.0 Creation 2009-03-30 Liao Huanran Wang Zhoujie
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Contents
1 Introduction to the SGSN9810 .................................................................................................... 8
1.1 Structure of a GPRS/UMTS Network .............................................................................................................. 8
1.2 Huawei GPRS/UMTS CN-PS Solution ........................................................................................................... 9
1.2.1 SGSN .................................................................................................................................................... 10
1.2.2 GGSN .................................................................................................................................................... 10
1.2.3 HA ......................................................................................................................................................... 10
1.2.4 CG ......................................................................................................................................................... 11
1.2.5 AAA Server ........................................................................................................................................... 11
1.2.6 DNS Server ........................................................................................................................................... 11
1.2.7 BG ......................................................................................................................................................... 11
1.3 Overview of the SGSN9810 ........................................................................................................................... 12
2 Key Benefits ................................................................................................................................. 15
2.1 Large Capacity and High Integration ............................................................................................................. 15
2.2 High-Speed Hardware Forwarding ................................................................................................................ 15
2.3 Supporting Boards of 750C Series ................................................................................................................. 15
2.4 Standard Protocol Interfaces .......................................................................................................................... 16
2.5 Abundant Physical Interfaces ......................................................................................................................... 17
2.6 Rich Services and Functions .......................................................................................................................... 17
2.7 Accurate Clock System .................................................................................................................................. 18
2.8 Easy Operation and Maintenance ................................................................................................................... 18
2.9 High Reliability .............................................................................................................................................. 19
3 System Structure ......................................................................................................................... 20
3.1 Hardware Configuration ................................................................................................................................. 20
3.1.1 Cabinet Configuration ........................................................................................................................... 20
3.1.2 Switching Subrack ................................................................................................................................ 22
3.1.3 Basic Subrack........................................................................................................................................ 23
3.1.4 Extended Subrack ................................................................................................................................. 25
3.2 Software Structure .......................................................................................................................................... 26
3.3 Logical Structure ............................................................................................................................................ 27
3.3.2 Switching Subsystem ............................................................................................................................ 28
3.3.3 PS Transfer Subsystem.......................................................................................................................... 28
3.3.4 Gb Interface Processing Subsystem ...................................................................................................... 28
3.3.5 Signaling Processing Subsystem ........................................................................................................... 29
3.3.6 Lawful Interception Subsystem............................................................................................................. 29
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3.3.7 Charging Subsystem ............................................................................................................................. 29
3.3.8 Iu Interface Control Plane Processing Subsystem ................................................................................. 29
3.3.9 GTP Control Plane Processing Subsystem ............................................................................................ 29
3.3.10 Operation and Maintenance Subsystem .............................................................................................. 29
3.3.11 Clock Subsystem ................................................................................................................................. 29
4 Services and Functions ............................................................................................................... 30
4.1 Services .......................................................................................................................................................... 30
4.1.1 IP/PPP Bearer Services ......................................................................................................................... 30
4.1.2 Short Message Services ........................................................................................................................ 31
4.1.3 Location Services .................................................................................................................................. 32
4.1.4 CAMEL Phase 3 Services ..................................................................................................................... 33
4.1.5 Lawful Interception ............................................................................................................................... 34
4.2 Functions ........................................................................................................................................................ 35
4.2.1 Mobility Management ........................................................................................................................... 36
4.2.2 Session Management............................................................................................................................. 36
4.2.3 Routing .................................................................................................................................................. 36
4.2.4 IPv6 Support ......................................................................................................................................... 37
4.2.5 IPSec and LLC Encryption ................................................................................................................... 38
4.2.6 Charging ................................................................................................................................................ 38
4.2.7 QoS ....................................................................................................................................................... 39
4.2.8 Iu-FLEX/Gb-FLEX ............................................................................................................................... 40
4.2.9 RAN Sharing in Connected State .......................................................................................................... 41
4.2.10 MVNO ................................................................................................................................................ 42
4.2.11 UESBI-Iu ............................................................................................................................................ 43
4.2.12 Multi-SPs and 2 Mbit/s Signaling Links ............................................................................................. 44
4.2.13 NTP Client Functions .......................................................................................................................... 45
4.2.14 Network-Assisted Cell Change ........................................................................................................... 47
4.2.15 SIGTRAN Support .............................................................................................................................. 47
4.2.16 Gb over IP ........................................................................................................................................... 49
4.2.17 Differential Services ........................................................................................................................... 50
4.2.18 Handover Strategy Control ................................................................................................................. 50
4.2.19 Enhanced MBMS ................................................................................................................................ 51
4.2.20 Network Share .................................................................................................................................... 52
4.2.21 Security Solution ................................................................................................................................. 53
4.2.22 Bidirectional Forwarding Detection (BFD) ........................................................................................ 55
4.2.23 One Tunnel .......................................................................................................................................... 55
4.2.24 SGSN N+1Backup .............................................................................................................................. 56
4.2.25 Multi SIM............................................................................................................................................ 56
5 Operation and Maintenance ..................................................................................................... 58
5.1 O&M System ................................................................................................................................................. 58
5.2 Configuration Management ............................................................................................................................ 59
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5.3 Equipment Management ................................................................................................................................ 59
5.4 Tracing Management ...................................................................................................................................... 59
5.5 Performance Management .............................................................................................................................. 60
5.6 Fault Management .......................................................................................................................................... 60
5.7 Security Management ..................................................................................................................................... 60
5.8 CHR ............................................................................................................................................................... 60
5.9 SSL ................................................................................................................................................................. 61
5.10 SSH .............................................................................................................................................................. 62
5.11 Online Help .................................................................................................................................................. 63
6 Reliability ..................................................................................................................................... 64
6.1 Hardware Reliability ...................................................................................................................................... 64
6.1.1 Board Hot Backup ................................................................................................................................. 64
6.1.2 ASIC Technology .................................................................................................................................. 64
6.1.3 Quality Components ............................................................................................................................. 64
6.1.4 Load Sharing ......................................................................................................................................... 65
6.1.5 Power Supply Reliability ...................................................................................................................... 65
6.2 Software Reliability ....................................................................................................................................... 65
6.2.1 Reliability Building at Different Phases ................................................................................................ 65
6.2.2 Error Tolerance ..................................................................................................................................... 65
6.3 Charging Reliability ....................................................................................................................................... 66
7 Technical Specifications ............................................................................................................ 67
7.1 Performance Specifications ............................................................................................................................ 67
7.2 Physical Interfaces ......................................................................................................................................... 67
7.3 Clock Indexes ................................................................................................................................................. 68
7.4 Engineering Specifications ............................................................................................................................. 70
7.4.1 Power Consumption .............................................................................................................................. 70
7.4.2 Dimensions and Weight of Cabinets ..................................................................................................... 71
7.4.3 Environment Requirements ................................................................................................................... 71
7.5 Reliability Specifications ............................................................................................................................... 72
8 Installation.................................................................................................................................... 73
A Acronyms and Abbreviations .................................................................................................. 74
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1 Introduction to the SGSN9810 The SGSN9810 is a core device of the packet domain of the GPRS/UMTS core network.
1.1 Structure of a GPRS/UMTS Network
The current wireless technology is evolving from 2G global system for mobile
communications (GSM) to 3G UMTS by way of 2.5G GPRS. Mobile communication
networks now cover large areas, transfer data in high speed, and can access the Internet. These
networks provide a wide range of multimedia services such as voice, data, and video and can
be accessed anytime and anywhere.
Figure 1-1shows the structure of a GPRS/UMTS network.
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Figure 1-1 Structure of a GPRS/UMTS network
Other PLMN
NodeB
RNC
UMTS UTRAN
RANGSM/GPRS BSS
BSC
CN-CS
MGW/MSC
Server
HLR
SGSN
Firewall
BG
DNS Server
SMS-GMSC
SMS-IWMSC
GMSC
Billing
Center
CG
GGSN/
FA
CN-PS
DNS
ServerWAP
Gateway
AAAServer
Firewall
BTSMS
HA
Core
Network
PSTN,
ISDN
Internet,
Intranet,
etc.
SS7
EIR
MS
As shown in Figure 1-1, a GPRS/UMTS network consists of the following parts:
Mobile station (MS): user equipment capable of originating and receiving calls over the
air interface. To handle data services, the MS establishes a logical link with the packet
switched (PS) domain.
Radio access network (RAN): handles all radio related functions.
Core network-circuit switching (CN-CS): provides circuit services and connects to
external circuit switched networks, such as a public switched telephone network (PSTN).
CN-PS: provides packet data services and connects to external public data networks
(PDNs), such as the Internet.
1.2 Huawei GPRS/UMTS CN-PS Solution The Huawei GPRS/UMTS CN-PS consists of the following main network entities:
Serving GPRS support node (SGSN)
Gateway GPRS support node (GGSN) and foreign agent (FA)
Home agent (HA)
Charging gateway (CG)
Authentication, authorization, accounting (AAA) server
Domain name system (DNS) server
Border gateway (BG)
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The CN-PS offers the means for an MS to access an external PDN. It provides packet data
services and charging services, such as prepaid and postpaid services.
1.2.1 SGSN
The SGSN is a functional entity that provides packet data services. It forwards incoming and
outgoing internet protocol (IP) packets to the mobile stations (MSs) within its service area.
The SGSN provides the following functions:
Routing and forwarding of data packets
Encryption and authentication
Session management
Mobility management
Logical link management
Generation and output of call detail records (CDRs)
1.2.2 GGSN
The GGSN is also a functional entity that provides packet data services. It routes and
encapsulates packet data between the GPRS/UMTS network and an external PDN.
The GGSN provides the following functions:
Interface to an external PDN
The GGSN serves as a gateway for an MS to access the external PDN. For the external
network, the GGSN serves as a router for all equipment in the GPRS/UMTS network.
GPRS/UMTS session management
The GGSN sets up a connection between an MS and the external PDN.
Data routing and forwarding
The GGSN receives data from the MS and then forwards the data to the external PDN. It
also receives data from the external PDN and selects a transport channel in the
GPRS/UMTS network based on the destination address to forward the data to the SGSN.
FA functions
To support mobile Internet Protocol (IP) services, the GGSN is embedded with FA
functions. In this case, the GGSN/FA serves as a gateway of the GPRS/UMTS network
and an FA of the network visited by the MS.
Charging for postpaid services
The GGSN generates and outputs CDRs based on the usage of the external network by
the subscribers.
Call control and service switching functions for prepaid services
For prepaid services, the GGSN serves as a service switching point (SSP) that connects a
mobile network and an intelligent network.
1.2.3 HA
The HA is an entity that is used to support mobile IP access. It is an enhanced router that also
maintains the current location information of the MSs.
The HA has the following function:
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Sending broadcast messages to the MSs so that the MSs know if they are on the home
network.
Handling and replying the registration requests from an MS. Generating mobility binding
records (MBRs) between the MS home address and care-of address.
Agency and forwarding: The HA reports the availability of network prefixes for the MS
home address so that the packets for the MS home address can be routed to the home
network. After encapsulating the packets, the HA tunnels them to the GGSN/FA, and
then the GGSN/FA finally forwards the packets to the MS.
1.2.4 CG
The CG is a new device added to the GPRS/UMTS network. It collects, consolidates, and
preprocesses CDRs generated by the SGSN or the GGSN. It provides an interface to the
billing center.
The CDRs are generated by several network entities when a GPRS or UMTS subscriber visits
the Internet. Each entity may generate several CDRs.
The CG is used to reduce the work load of the billing center by consolidating and
preprocessing the CDRs before sending them to the billing center. With the CG in the network,
the SGSN or the GGSN need not provide the charging interface to the billing center.
1.2.5 AAA Server
The AAA server carries out authentication, authorization and accounting according to the
Remote Authentication Dial-In User Service (RADIUS) protocol.
The AAA server is not specific to the GPRS/UMTS system.
1.2.6 DNS Server
There are two types of DNS server in a GPRS/UMTS network.
The first is the DNS between the GGSN and the external PDN. As an ordinary DNS on the
Internet, this DNS resolves the domain name of the external PDN.
The second is the DNS on the GPRS/UMTS CN. The main functions of the DNS server
include the following:
Resolves the GGSN IP address from the access point name (APN) to set up a connection
between the GGSN and the MS when the MS accesses the external PDN.
Resolves the SGSN IP address from the old routing area code during the inter-SGSN
routing area update.
Resolves the SGSN IP address from the new radio network controller (RNC) identity (ID)
during RNC relocation.
The DNS server is not specific to the GPRS/UMTS system.
1.2.7 BG
The BG is a router. In addition to security functions, it provides a routing function between
the SGSN and the GGSN in different PLMNs.
The BG is not specific to the GPRS/UMTS system.
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The FA and the HA are mandatory for mobile IP access. If the mobile IP access function is not required,
the FA and the HA are not required.
1.3 Overview of the SGSN9810 The SGSN9810 can be used in a GPRS and a UMTS network. It supports up to 3 million
subscribers attached to the network at the same time.
Figure 1-2 shows the SGSN9810 appearance.
Figure 1-2 SGSN9810 appearance
The SGSN9810 provides a wide range of services, functions, protocol interfaces, and physical
interfaces. Built on the mature platform of Huawei products, it is reliable and easy to operate.
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The main functions of the SGSN9810 are listed as follows:
IP bearer services
Mobility management
Security management
Session management
Charging
Quality of service (QoS) and flow management
Static and dynamic routing
Simple network management protocol (SNMP) support
Optional functions include:
Point-to-Point Protocol(PPP) bearer services
Short message service (SMS)
Customized applications for mobile network enhanced logic (CAMEL) 3 intelligent
services
Location service (LCS)
Internet protocol security extensions (IPSec) function
Lawful interception
2 Mbit/s signaling link
Multiple signaling points
Network time protocol (NTP)
Multiple HPLMNs
Iu-FLEX
Mobile virtual network operator (MVNO)
Network assisted cell change (NACC)
IP multimedia subsystem (IMS) bearing
IPv6
RAN sharing in connected mode
UESBI-Iu
Enhanced data rates for GSM evolution (EDGE)
High speed downlink packet access (HSDPA)
Differential service
Handover strategy control
Gb over IP
Signaling transport (SIGTRAN) support
SGSN N+1 backup
One Tunnel
Multi-SIM
APN error correction
The following features are added in the SGSN9810 V800R009 version:
Supporting boards of 750C series
Enhanced multimedia broadcast and multicast service (MBMS)
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Network share in the gateway core network (GWCN)
Security solution
Security Socket Layer (SSL)
Bidirectional forwarding detection (BFD)
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2 Key Benefits The SGSN9810 is a competitive SGSN product offered by Huawei. It has multiple features
and functions.
2.1 Large Capacity and High Integration
If the boards of 750B series are used, the SGSN9810 can support a maximum of 2 million
2.5G and 3G attached subscribes concurrently. A fully configured SGSN9810 system requires
five cabinets for a 2.5G network or three cabinets for a 3G network.
If the boards of 750C series are used, the SGSN9810 can support a maximum of 3 million
2.5G and 3G attached subscribes concurrently. Only two cabinets are required for
configuration of 2 million 2.5G or 3G subscribers, whereas three cabinets are required for
configuration of 3 million subscribers.
2.2 High-Speed Hardware Forwarding
The user plane data of the SGSN9810 is forwarded using hardware. This improves the
processing efficiency and integration of the system.
The hardware supports the traffic at the rate of 900 Mbit/s in a 2.5G system or the traffic at
the rate of 10 Gbit/s in a 3G system.
2.3 Supporting Boards of 750C Series
The SGSN9810 supports the boards of 750C series and thus the system performance and
specification are greatly improved. As a result, the SGSN can meet the present and future
performance requirements.
Table 2-1 lists the hardware comparison between the 750C series and the 750B series.
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Table 2-1 Hardware comparison
Hardware 750C 750B
CPU
750GX(clock frequency
1GHz)
750(clock frequency
500MHz)
Memory 1GB 512MB
FLASH 32M 16M
The maximum number of subscribers supported by the SGSN increases to 3 million. The
number of cabinets for 2 million 2.5G subscribers decreases from five to two and that for 3G
subscribers decreases from three to two.
2.4 Standard Protocol Interfaces
The SGSN9810 supports a variety of 3rd Generation Partnership Project (3GPP) protocol
interfaces to connect to the equipment from different vendors. This makes network
deployment easy for operators.
Figure 2-1 shows the protocol interfaces supported by the SGSN9810.
Figure 2-1 Protocol interfaces supported by the SGSN9810
Gf
Gi
GnIu
Gc
Gp
Gs
MSC/VLR
TE MT UTRAN TEPDN
Gr
HLR
Other PLMN
SGSN
GGSN
Gd
SM- SCSMS-GMSC
SMS-IWMSC
GGSN
EIRSGSN
GnCGF
GaGa
Billing
System
Gb
TE MT BSS
CAMEL GSM-
SCF
Ge
GLMC
Lg
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2.5 Abundant Physical Interfaces
The SGSN9810 provides the following physical interfaces to adapt different networks:
Gn, Gp, Ga, Iu-CS, and Iu-PS interfaces: STM-1, STM-4, 10 Mbit/s, 100 Mbit/s, and
1,000 Mbit/s Ethernet interfaces
Gb, Gd, Ge, Gf, Gr, Gs, and Lg interfaces: E1, T1, STM-1, STM-4, 10 Mbit/s, 100
Mbit/s, and 1,000 Mbit/s Ethernet interfaces
The 1,000 Mbit/s Ethernet interfaces support both optical ports and electrical ports.
2.6 Rich Services and Functions
The SGSN9810 provides a wide range of services and functions. The basic functions include:
IP bearer services
Mobility management
Security management
Session management
Charging
Quality of service (QoS) and flow management
Static and dynamic routing
Simple network management protocol (SNMP) support
Optional functions include:
Point-to-Point Protocol(PPP) bearer services
Short message service (SMS)
Customized applications for mobile network enhanced logic (CAMEL) 3 intelligent
services
Location service (LCS)
Internet protocol security extensions (IPSec) function
Lawful interception
2 Mbit/s signaling link
Multiple signaling points
Network time protocol (NTP)
Multiple HPLMNs
Iu-FLEX
Mobile virtual network operator (MVNO)
Network assisted cell change (NACC)
IP multimedia subsystem (IMS) bearing
IPv6
RAN sharing in connected mode
UESBI-Iu
Enhanced data rates for GSM evolution (EDGE)
High speed downlink packet access (HSDPA)
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Differential service
Handover strategy control
Gb over IP
Signaling transport (SIGTRAN) support
Supporting boards of 750C series
Enhanced multimedia broadcast and multicast service (MBMS)
Network share in the gateway core network (GWCN)
Security solution
Security Socket Layer (SSL)
Bidirectional forwarding detection (BFD)
2.7 Accurate Clock System A clock synchronization system is required when the SGSN9810 uses the E1/T1 interface and
the STM-1 or STM-4 optical interface to interconnect with other devices. The clock system of
the SGSN9810, using the advanced digital phase-locked loop and reliable software
phase-locked technology, has the following features:
It provides stratrum-2 (A and B types) and stratum-3 clocks.
The stratum-2 and stratum-3 clocks can be flexibly configured through terminals.
It provides multiple input reference signals, which include 2.048 MHz and 2.048 Mbit/s.
It provides powerful software functions, including display, alarm, O&M functions. The
operators can conveniently control the phase-locked method and the source reference of
the clock through the maintenance console.
It has powerful phase-locked capability and adapts to all kinds of clock transmission. In
case that the clock reference has fault, the clock synchronization system of the
SGSN9810 can work in free running mode and keep synchronization.
2.8 Easy Operation and Maintenance The operation and maintenance (O&M) system of the SGSN9810 has the following features:
Flexible O&M methods
The O&M system can be flexibly built according to the network structure and customer
requirements. Multiple maintenance interfaces are supported, including the interfaces to
the local maintenance terminal (LMT), the Huawei centralized network management
system iManager M2000, and the Simple Network Management Protocol (SNMP) based
on the network management system. Through the Common Object Request Broker
Architecture (CORBA) interface provided by the iManager M2000, more network
management requirements can be fulfilled.
Friendly user interfaces
The SGSN9810 provides O&M interfaces that combines the merits of both man-machine
language (MML) and graphic user interface (GUI).
Powerful signaling tracing
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The SGSN9810 provides functions to trace the messages of designated subscribers and
the signals on the protocol interfaces such as the Iu, Gb, Gs, and Gr. The SGSN9810 also
provides message explanation and filtering.
Software patching in function level
Through online software patching, software errors can be solved without interrupting
services. The SGSN9810 also supports remote patching and version fallback.
2.9 High Reliability
The SGSN9810 is highly reliable because of the following features:
Backup of important data
The SGSN9810 automatically backs up important data, such as the configuration data,
performance data, and operation logs.
Operation security management
Different management privileges are assigned to different users. During the user login,
the SGSN9810 checks the user identity. After the user login, the SGSN9810 maintains
the complete operation to ensure system security.
CG redirection and bill buffering
When the active CG or the link to the active CG fails, the SGSN9810 sends the bills to
the standby CG. If the standby CG is also faulty, the SGSN9810 stores the bills in its
buffer.
Hardware redundancy design
All critical boards are configured in the 1+1 backup or N+1 redundancy to ensure the
high reliability of the system.
Fault Avoidance
The SGSN9810 provides protection mechanisms to avoid the following system faults:
System power off
Maloperation on system power switch
Lightning surge on the system power
High voltage and low voltage
Short circuit of power supply
Lightning surge on E1/T1 links
Current surge and high voltage on the power supply and interfaces
System overload control
In the case of center processing unit (CPU) overload or resource congestion, the
SGSN9810 adjusts the traffic smoothly to avoid system down.
Board locking and system shutdown
This function ensures that a service can slowly exit from a board or the system if
required without interrupting other services.
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3 System Structure The system structure of the SGSN9810 includes hardware structure, software structure, and
logical structure.
3.1 Hardware Configuration
The SGSN9810 hardware consists of the cabinet, subrack, and board.
Cabinet
The SGSN9810 uses Huawei's N68-22 cabinet. This cabinet is a standard 19-inch one
and is in compliance with the IEC297. The SGSN9810 requires 1~6 cabinets.
Subrack
The SGSN9810 uses the standard 19-inch subrack, which is also called the PSM subrack.
A maximum of four PSM subracks can be configured in each cabinet. Each PSM subrack
contains 21 slots. Boards are inserted in front and rear of the backplane.
According to the board configuration, the PSM subrack is classified into three types,
namely, switching subrack, basic subrack and extension subrack.
Board
According to the position, the boards of the SGSN9810 are classified into the front card,
back card, and pinch board. The number of boards depends on the capacity of the
system.
3.1.1 Cabinet Configuration
Figure 3-1 shows an example of the cabinet configuration of the SGSN9810.
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Figure 3-1 Hardware configuration of the SGSN9810
PSM Subrack
Air Deflector
Air Deflector
Air Deflector
Dummy Panel
Power Distribution Box
PSM Subrack
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3.1.2 Switching Subrack
The switching subrack refers to the PSM subrack that is configured with the UFCU boards.
Only one switching subrack is required.
The fundamental function of the switching subrack is to forward data among the PSM
subracks.
Figure 3-2 shows the boards in the switching subrack.
Figure 3-2 Boards in the switching subrack
U
F
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In Figure 3-2, the boards in the upper half of the subrack are inserted from the rear, and the boards in the
lower half are inserted from the front.
Table 3-1 briefs the functions of the boards in the switching subrack.
Table 3-1 Functions of the boards in the switching subrack
Board Function
Subrack control unit (URCU) Bus mediation
Board configuration
Maintains boards
Controls the PSM subrack
PSM back interface unit (UBIU) Provides optical ports, network ports, and serial ports
for the URCU.
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Board Function
Auxiliary control unit (UACU) Works with the URCU board to control the two
buses in the PSM subrack.
Controls hot swap of the service processing boards
in the PSM subrack.
Controls the switchover of URCU boards.
PSM alarm unit (UALU) Monitors the power module of the PSM subrack.
Monitors back board status.
Monitors subrack temperature.
PSM power module (UPWR) Provides power supply for the PSM subrack.
Frame connect unit (UFCU) Forwards service subrack data.
Packet interface unit (UPIU) Receives and forwards Asynchronous Transfer Mode
(ATM) data and Ethernet link data.
GTP forwarding unit (UGFU) Forwards GPRS Tunneling Protocol (GTP) data.
Charging detail record unit
(UCDR)
Collects, encodes, and sends CDRs, and stores CDRs
in the buffer.
Back storage unit (UBSU) Provides external interfaces and a hard disk for the
UCDR.
GTP processing unit (UGTP) Forwards GPRS tunneling protocol for control plane
(GTP-C) signaling messages and implements the
charging function of GPRS tunneling protocol for
user plane(GTP-U) data
For NTP, DNS client and IPSec functions
3.1.3 Basic Subrack
The basic subrack refers to the PSM subrack that is configured with the UOMU boards. Only
one basic subrack is required.
The fundamental function of the basic subrack is to provide operation and maintenance to the
system, including operator management, configuration management, alarm management,
tracing management, and performance measurement.
Figure 3-3 to Figure 3-4 show the boards in the basic subrack for 2.5G network and 3G
network.
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Figure 3-3 Boards in the basic subrack (2.5G network)
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G
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Figure 3-4 Boards in the basic subrack
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Table 3-2 briefs the functions of the boards in the basic subrack.
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Table 3-2 Functions of the boards in the basic subrack
Board Function
Clock unit (UCKI) Provides operation clock for the SGSN9810
Packet service signal
processing unit (USPU)
For application layer protocols such as Session Management
(SM), Mobility Management (MM), and Customized
Applications for Mobile network Enhanced Logic (CAMEL)
Processes Signaling System No.7 (SS7) L3 messages
Gb interface unit (UGBI) For Gb interface protocols
Iu_PS control processing
unit (UICP)
For Iu-PS control plane protocols
Packet service O&M unit
(UOMU)
For the operation and maintenance functions of the
SGSN9810
PSM flashdisk storage unit
(UFSU)
Provides external interfaces and a hard disk for the UOMU
E1 processing interface
unit (UEPI)
Provides external E1 interfaces for the Packet Service Signal
Processing Unit (USPU) or Gb Interface Unit (UGBI)
T1 processing interface
unit (UTPI)
Provides external T1 interfaces for the USPU or UGBI
LAN switch card (ULAN) Serves as a local area network (LAN) switch to provide a
connection between the UOMU and URCU
SIGTRAN process unit
(USIG)
For the MTP3 User Adaptation Layer (M3UA) and Stream
Control Transmission Protocol (SCTP) of the SIGTRAN
Lawful interception
processing unit (ULIP)
Provides the following interfaces for lawful interception:
The interfaces for receiving interception requests
The interfaces for collecting and transmitting interception
messages
Lawful Interception
Enhanced Processing
Unit(ULEP)
For Lawful Interception Enhanced Processing Unit
3.1.4 Extended Subrack
The extended subracks process services. An extended subrack can be configured to process
2.5G services, 3G services, or both.
Figure 3-5 shows the boards in a extended subrack for both 2.5G and 3G services. For the
description of these boards, see Table 3-2.
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Figure 3-5 Boards in the extended subrack (2.5/3G)
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3.2 Software Structure
The SGSN9810 is a distributed system where functions are distributed in and implemented by
different boards. Each board has its own software that consists of a platform module and
function-specific modules.
Figure 3-6 shows the structure of the SGSN9810 software.
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Figure 3-6 Structure of the SGSN9810 software
Platform management sub-system (OS and DOPRA)
O&M sub-system
Device management
sub-system
Database
management sub-
systemUGFU UFCU
USPU UCDR
ULIP UGTP
UICP
Service feature plane
Data forwarding plane System management plane
Data service plane
UGBI
The data service plane consists of a platform management subsystem, that is, the operating
system (OS) and the Distributed Object-oriented Programmable Real-time Architecture
(DOPRA). This plane is the basis of other software modules.
The system management plane manages the whole SGSN9810 system. It consists of
three subsystems:
O&M
Device management
Database management
The system management plane and the data service plane are the basic modules in each
board software.
The data forwarding plane consists of the UGFU and UFCU. It carries out the switching,
routing, and forwarding of ATM and IP packets.
The service plane processes services. It consists of the USPU, UCDR, ULIP, UGBI,
UGTP, and UICP.
3.3 Logical Structure The SGSN9810 has twelve logical functional subsystems, as shown in Figure 3-7.
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Figure 3-7 Logical structure of the SGSN9810
Switching
subsystem
PS transfer
subsystem
Gb interface
processing
subsystem
Signaling
processing
subsystem
Clock subsystem
Operation and
maintenance
subsystem
Iu interface
control
plane
processing
subsystem
GTP
control
plane
processing
subsystem
Lawful
interception
subsystem
Charging
subsystem
GGSN
NTP
DNS
RNC
BITS
ATM
IP HLR
E1/T1
LMT
M2000
IP
PCU
This section briefs the functions of these subsystems and the hardware that implements the
functions.
3.3.2 Switching Subsystem
Function: Packets switching and interconnection between subracks
Hardware: URCU, UPIU, and UFCU
3.3.3 PS Transfer Subsystem
Function: routing and forwarding of GTP user data; Gn/Gp external interfaces
Hardware: UGFU and UPIU
3.3.4 Gb Interface Processing Subsystem
Function: implementing L1, Network Service (NS) and Base Station Subsystem GPRS
Protocol (BSSGP) layer protocols of the Gb interface
Hardware: UGBI and E1 processing interface unit (UEPI) or T1 processing interface unit
(UTPI)
The UEPI or UTPI is not required when the Gb over IP function is enabled.
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3.3.5 Signaling Processing Subsystem
Function: implementing L1, L2, and L3 of the Message Transfer Part (MTP), SIGTRAN,
Signaling Connection and Control Part (SCCP), Mobile Application Part (MAP), MM, SM,
CAMEL, and Location Service (LCS) protocols.
Hardware: USPU, SIGTRAN process unit (USIG), and UEPI/UTPI
3.3.6 Lawful Interception Subsystem
Function: X1-1/X2/X3 interfaces, collection and transmission of lawful interception data
Hardware: ULIP and ULEP
3.3.7 Charging Subsystem
Function: collection, storage, coding, and transmission or CDR data
Hardware: UCDR
3.3.8 Iu Interface Control Plane Processing Subsystem
Function: implementing the control plane Signaling ATM Adaptation Layer (SAAL), MTP3B,
SCCP, and Radio Access Network Application Part (RANAP) protocols of the Iu interface
Hardware: UICP
3.3.9 GTP Control Plane Processing Subsystem
Function: implementing the GTP-C protocol and IPSec encryption of GTP-C signaling
messages
Hardware: UGTP
3.3.10 Operation and Maintenance Subsystem
Function: external O&M interfaces, system O&M, configuration management, performance
management, alarm management, and operation logs
Hardware: UOMU and Flash Storage Unit (UFSU)
3.3.11 Clock Subsystem
Function: providing stratum-2 or stratum-3 clock (secondary clock) for the system
Hardware: clock unit (UCKI)
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4 Services and Functions The SGSN9810 offers abundant services and functions, and meets the requirements of
multiple networks and operations.
4.1 Services
The SGSN9810 provides a full range of services to meet the demands of various subscribers.
This section introduces the following services:
IP/PPP bearer services
Short message services (SMS)
Location services
CAMEL Phase 3 services
Lawful interception
4.1.1 IP/PPP Bearer Services
The GPRS/UMTS network supports protocols such as the IPv4, IPv6, and Point-to-Point
Protocol (PPP).
The IP/PPP packets can travel transparently on the GPRS/UMTS network. Subscribers can
use various IP and PPP applications, such as web browsing, File Transfer Protocol (FTP), and
Virtual Private Network (VPN), through the GPRS/UMTS network.
Figure 4-1 shows the structure of the protocol stacks that provide IP and PPP bearer services
in a 3G network.
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Figure 4-1 IP/PPP bearer protocols (3G)
3G-SGSNUTRANMSIu-PS Gn Gi
3G-GGSNUu
L1
RLC
PDCP
MAC
Application
E.g.,
IP,PPP
L1
RLC
PDCP
MAC
L1
UDP/IP
GTP-U
L2
Relay Relay
L1
UDP/IP
L2
GTP-U
E.g.,
IP,PPP
L1
UDP/IP
GTP-U
L2
L1
UDP/IP
GTP-U
L2
Figure 4-2 shows the structure of the protocol stacks that provide IP and PPP bearer services
in a 2.5 network.
Figure 4-2 IP/PPP bearer protocols (2.5G)
L2
Application
IP
SNDCP
LLC
RLC
MAC
GSM RF
LLC
BSSGP
L1bis L1
IP
L2
L1
IP
GTP-U
IP
Um Gb GnMS BSS SGSN GGSN
NetworkService
UDPUDP
MAC
GSM RF L1bis
NetworkService
RLC BSSGP
Relay
Relay
SNDCP GTP-U
Gi
4.1.2 Short Message Services
Short message services (SMS) include normal SMS and enhanced SMS.
Normal SMS allows for the messages that contain up to 160 bytes (including control
bytes).
Enhanced SMS allows for formats in a message in addition to texts. These formats may
include objects such as animations and images. A short message can contain more than
one object.
SMS consists of two types of basic service:
mobile terminated short message (SM-MT)
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SM-MT is the capability that enables the GSM/UMTS system to deliver the short
messages submitted by the short message center (SMC) to the specified MS. At the same
time, result (success or failure) of the message delivery is provided. In the case of
delivery failure, a repeat strategy is implemented.
mobile originated short message (SM-MO)
SM-MO is the capability that enables the GSM/UMTS system, with the help of the SMC,
to forward the short messages submitted by an MS to the short message entity (SME). At
the same time, result (success or failure) of the message submission is provided.
Figure 4-3 shows the basic network structure of the SMS.
Figure 4-3 Basic network structure of the SMS
No.7
MSC
SGSN
RNC
BSC/PCU
NodeB
BTS
SMC
The GPRS-attached MSs or the GPRS-attached but international mobile subscriber identity
(IMSI) -unattached MSs submit and receive short messages through the PS domain.
The GPRS-attached and IMSI-attached MSs submit and receive short messages through either
the PS domain or the circuit switching (CS) domain. If the messages are submitted through
the CS domain, the SGSN can be used for paging.
4.1.3 Location Services
The LCS enables the GPRS/UMTS network to locate an MS in the network and provide the
geographic location of the MS after data conversion and calculation.
The location data can be applied internally or externally.
For internal purposes, it can be used by the operator to fulfill certain requirements such
as location-based charging.
For external purposes, it can be used by the network to provide various location-based
services such as on-demand services, customized messages, and customized services.
Figure 4-4 shows the network of the LCS.
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Figure 4-4 Network of the LCS
GMLC
2G-
MSC
3G-
SGSN
2G-
SGSN
MSC
server
gsmSCF
LgGb
A
Lg
Lc
Le
Iu
HSS
Iu
Iu
Lg
Um
Uu
LgLh
External LCSClient
Iu
LIF-MLP
OSA APIProprietary
OSA SCS
Proprietary
UE
GERAN
UTRAN
The LCS network includes the following major entities:
LCS client
The LCS client originates location requests. Corresponding to the application of LCS,
the LCS client includes the internal LCS client and the external LCS client.
GMLC
The Gateway mobile location center (GMLC) provides an path for the LCS client to
access the public land mobile network (PLMN).
After receiving the location request from the LCS client, the GMLC requests routing
data from the home location register (HLR) or the home subscriber server (HSS).
At the same time, the GMLC forwards the request to the visited mobile switching center
(VMSC), SGSN, or MSC server after authentication.
The location result is also forwarded through the GMLC.
MSC, MSC server, and SGSN
These entities connect to the GMLC through the Lg interface. They receive, process, and
respond to the location request.
4.1.4 CAMEL Phase 3 Services
The CAMEL enables operators to provide subscribers special services such as the prepaid
service.
Figure 4-5 shows how the SGSN supports CAMEL Phase 3 services in a GPRS/UMTS
network.
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Figure 4-5 SGSN support to CAMEL Phase 3 services
MS
Visiting NetworkInterrogating Network
Home Network
CAP
Home/Interrogating/Visiting Network
MAP
HLR gsmSCF
SGSN
gprsSSF
As shown in the figure, the SGSN integrates the GPRS service switching function (gprsSSF)
and provide CAMEL Phase 3 services under the control of the GSM service control function
(gsmSCF).
4.1.5 Lawful Interception
The lawful interception is a capability of the mobile network to provide the content of
communication (CC) of MSs and intercept related information (IRI) to a law enforcement
agency (LEA).
Figure 4-6 shows the procedure of lawful interception.
Figure 4-6 Procedure of lawful interception
Network node
ADMF
DF2
DF3
X1-1
X2
X3
LEA
Intercept request
IRI
CC
Intercept reques
The procedure for lawful interception is as follows:
1. The LEA sends an intercept request to the administration function (ADMF) entity.
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2. The ADMF forwards the request to the network node.
3. The network node starts intercepting the CC of the target subscriber.
4. The network node forwards the IRI and CC of the target subscriber to the LEA through the delivery function (DF).
As shown in Figure 4-6, the logical entities relating to the interception in a mobile network
include the network nodes (SGSN and GGSN), ADMF, and DF.
The ADMF controls the interception while the DF collects and forwards the IRI and the CC.
Relevant interfaces include the X1-1 interface, X2 interface, and X3 interface.
X1-1 interface is between the ADMF and the network node.
It transfers interception-related management messages from the ADMF to the network
node.
X2 interface is between the DF2 and the network node.
It transfers the IRI.
X3 interface is between the DF3 and the network node.
It transfers the CC.
4.2 Functions The SGSN9810 provides powerful functions to meet the requirements of network operators.
This section introduces the following functions:
Mobility management
Session management
Routing
IPv6 support
IPSec and logical link control (LLC) encryption
Charging
QoS
Iu-FLEX/Gb-FLEX
RAN sharing in connected state
MVNO
UESBI-Iu
Multi-SPs and 2 Mbit/s signaling link
NTP client functions
Network assisted cell change (NACC)
SIGTRAN support
Gb over IP
Differential services
Handover strategy control
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4.2.1 Mobility Management
The MM function is used to control an MS access to the GPRS/UMTS network and trace the
location of the MS, such as the routing area (RA) and SGSN information of the MS.
The MM function is fulfilled mainly by attach, detach, and route updating procedures. It
ensures that the location of the MS is updated while the MS is moving, such as the updating
of the current SGSN information in the HLR.
4.2.2 Session Management
The SM carries out Packet Data Protocol (PDP) context management.
The PDP context is a group of messages related to the PDP. The network elements, such as
the MS, SGSN, and GGSN, send and manage the PDP data based on the PDP context.
Session management includes PDP context activation, modification, and deactivation.
Before the MS transmits data, it must activate the PDP context. During the data transfer, the
PDP context can be modified based on the requirement of the QoS. After data transfer, the
PDP context must be deactivated to release network resources.
4.2.3 Routing
The SGSN9810 supports various routing protocols to ensure the flexible networking using the
Gn/Gp interface.
Static Routing
Static routes are manually configured by the administrator. Users can configure static routes
to set up a connected network.
In a simple network, static routes can be used to ensure the stable operation of the router. Well
configured static routes can improve the performance of the network and ensure the
bandwidth for critical applications.
When the network is faulty, the static route cannot adjust itself and requires reconfiguration.
OSPF
The open shortest path first (OSPF) is an interior gateway protocol (IGP) developed by the
internet engineering task force (IETF). The OSPF is implemented based on link status.
The OSPF has the following features:
Large scope
The OSPF can be used for the networks of various sizes and support up to hundreds of
routers.
Fast convergence
After the network topology is changed, an update message is sent at once to synchronize
the data in the autonomous system.
Loop free
The OSPF uses the shortest path algorithm to determine a route based on the link status.
The algorithm ensures that the route is loop free.
Area division
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The network of the autonomous system can be divided into several areas so that the
network is easy to manage. The route information transferred between the areas is
abstracted, so the required bandwidth is further reduced.
Equivalent route
Multiple equivalent routes to the same destination are supported.
Hierarchical routes
Routes are classified into four categories. They are (from high to low priority) intra-area
routes, inter-area routes, class-1 external routes, and class-2 external routes.
RIP II
The routing information protocol (RIP) is a simple IGP that is used in small networks.
The RIP is widely used in networks thanks to the following features:
Easy to implement
Little protocol overhead which makes almost no impact on the network performance
Easy to configure and maintain compared with the OSPF and intermediate
system-to-intermediate system (IS-IS) intra-domain routing information exchange
protocol
4.2.4 IPv6 Support
The rapid development of Internet services requires more and more IP addresses, which are
beyond the capability of the IPv4 protocol. As a result, the IPv6 is developed to address this
problem.
Compared with the IPv4, the IPv6 boasts of the following advantages:
Extended IP addresses
IP addresses are extended from 32 bits in the IPv4 to 128 bits in the IPv6, indicating that
the address resources are abundant. This address structure also improves routing
efficiency.
Simplified packet header format
The packet header is simplified to minimize the processing by routers; thus it improves
routing efficiency.
Enhanced support for extension and option capability
The IPv6 satisfies additional requirements without affecting the routing of normal
packets or special packets.
Flow identity
The flow identity is used to improve the processing of packet flows, especially real-time
applications.
Identity verification and security
Enhanced identity verification and security measures make IPv6 especially suitable for
sensitive commercial information.
The data plane and the signaling plane of the SGSN9810 Gn/Gp interface supports both IPv4
and IPv6 addresses.
Operators can choose one of the following four operational modes:
Supporting only IPv6 addresses
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Preferring IPv6 addresses
Supporting only IPv4 addresses
Preferring IPv4 addresses
4.2.5 IPSec and LLC Encryption
To ensure the security of data transfer, the SGSN9810 supports IPSec encryption for the
signaling massages on the Gn/Gp interface and data encryption for the Gb interface messages.
IPSec
The SGSN9810 encrypts the Gn/Gp signaling messages by using the IP Security (IPSec)
protocols.
The IPSec is a series of protocols developed by the IETF to ensure the security of the data that
is transmitted on the Internet.
Through encryption and data source verification on the IP layer, the privacy and integrity of
data packets can be guaranteed when the packets are transferred on the Internet.
LLC Encryption
In a 2.5G system, the encryption on the Logical Link Control (LLC) layer between the MS
and SGSN is the traditional stream encryption using the GPRS-A5 algorithm.
The data to be encrypted includes the information field and the authentication field carried by
LLC frames.
4.2.6 Charging
Figure 4-7 shows the GPRS/UMTS charging network.
The SGSN and GGSN collect the charging information relating to radio network resource
usage and CN resource usage by each MS. Then they generate CDRs and send them to the
CG through the Ga interface.
Figure 4-7 GPRS/UMTS charging network
GGSN
CG Billing Centre
SGSN
Internet
BSC/PCU
RNC
BTS
NodeB
Gn
GaGa
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The SGSN9810 can generate the following seven CDRs:
SGSN generated - CDR(S-CDR): records the information related to certain PDP contexts
in the SGSN
Mobility management generated - CDR(M-CDR): records the mobility-related
information
SGSN delivered short message mobile originated - CDR(S-SMO-CDR): records the
information related to SM-MO services
SGSN delivered short message mobile terminated - CDR(S-SMT-CDR): records the
information related to SM-MT services
Mobile terminated LCS CDR(LCS-MT-CDR): records the information related to
mobile-terminated location services
Mobile originated LCS CDR(LCS-MO-CDR): records the information related to
mobile-originated location services
Network induced LCS CDR(LCS-NI-CDR): records the information related to
network-initiated location services
4.2.7 QoS
The 3GPP R5 specifications define four classes of QoS, as described in Table 4-1.
Table 4-1 UMTS QoS classes
Traffic Class Conversational Class
Streaming Class
Interactive Class
Background Class
Characteristics Preserve time
relation between
entities of the
stream
Conversational
pattern (high
quality, low delay)
Preserve time
relation
between
entities of the
stream
Request
response
pattern
Destination
does not expect
the data within
a certain time.
Example of the
application
Voice Video Web
browsing
Download or
sending
e-mails
The SGSN9810 support the four QoS classes by using the following mechanisms:
Access control
When the subscriber activates the PDP context, the SGSN negotiates the QoS with the
MS.
If the negotiation fails, the SGSN denies the MS access.
QoS queue management
The data packets are assigned to QoS queues based on the QoS class. The SGSN
dispatch the queues using the class-based weighted fair queuing (CBWFQ) algorithm to
decide the order of transmission.
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In case of congestion, the SGSN decides the discard criteria of packets by using the
weighted random early detection (WRED) algorithm. This ensures the transmission
reliability of the high-priority data.
Differentiated Services (DiffServ)
DiffServ is an IP QoS model that is used in a backbone network to meet various service
requirements.
In the DiffServ system, the network node determines the per-hop behavior (PHB)
according to the differentiated services code point (DSCP) in the IP header.
The SGSN supports the following PHBs: expedited forwarding (EF), assured forwarding
(AF), and best-effort (BE). It also supports the three discard priorities of the AF.
QoS mapping
QoS mapping converts the QoS attributes of different bearer protocols.
It includes the mapping between the 3GPP QoS and DSCP, between the DSCP and the
ATM QoS, and between the R97/98 and the R99 QoS attributes.
CAR and Remarking
If the actual data packet stream requires the QoS higher than the requested one, the
SGSN handles the packets based on the committed access rate (CAR) and discard the
extra packets.
SGSN can also carry out a Remarking process to lower the QoS of the data packet.
4.2.8 Iu-FLEX/Gb-FLEX
The Iu-FLEX/Gb-FLEX function allows one RAN or base station subsystem (BSS) to
connect to several CN nodes in the same domain.
The Iu-FLEX/Gb-FLEX function introduces the concept of pool areas. Similar to an MSC or
SGSN service area, a pool area contains one or more RAN/BSS service areas, but it is served
by multiple CN nodes (MSC or SGSN) at the same time. See Figure 4-8 for details.
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Figure 4-8 Example of pool area configuration
Area 1
RANnode
Area 5
RANnode
Area 6
RANnode
Area 7
RANnode
Area 8
RANnode
Area 2
RANnode
Area 3
RANnode
Area 4
RANnode
PS pool-area 2
PS pool-area 1
CS pool-area 2
CS pool-
area 1
MSC 3MSC 2
MSC 1
MSC 6MSC 5
MSC 4
SGSN 6
SGSN 2
SGSN 1
SGSN 5SGSN 4
SGSN 3
MSC 7
The Iu-FLEX/Gb-FLEX function expands the service areas of each CN node and reduces the
effort required for the inter-node update, handover, relocation, and HLR update.
This function also improves system availability. If one CN node in the pool area is faulty,
other nodes can provide services.
4.2.9 RAN Sharing in Connected State
Figure 4-9 shows the scenario of RAN sharing in connected state. In this scenario, the
networks of operator A and operator B together cover a large area in which an overlap area
exists. The RANs of operator A and operator B are connected through the CNs, so the user
equipment (UE) of operator B can operate in the network of operator A. In the overlap area,
the UE of operator B must access the RAN of operator B rather than the network of operator
A.
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Figure 4-9 RAN sharing between operators
Core Network A Core Network B
Radio Access Network
BRadio Access Network
A
To solve the problem mentioned above, the R5 protocol introduces the concept of shared
network area (SNA). An SNA corresponds to one or more location areas (Las) that control the
UE access.
The SNA is configured in the CN. The CN provides an SNA ID list that contains the SNAs
that the UE can access.
If the location area (LA) is in the SNA that the UE can access, the RAN allows the UE to
access the network. Otherwise, it denies the UE.
4.2.10 MVNO
A mobile virtual network operator (MVNO) uses the resources authorized by a mobile
network operator (MNO) to provide services and maintain the authorized resources.
The MVNO function enables more operators to invest on and share the network to lower the
investment risk and maximize resource usage.
The network resources authorized by the MNO can be the RAN, part of the CN, or the whole
CN. Figure 4-10 shows the example of partial CN sharing. In the example, the MNO shares
its SGSN with the MVNO, and the MVNO owns the GGSN, CG, and other network
equipment.
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Figure 4-10 MVNO network
GGSN
CG Billing Centre
SGSN
Internet
BSC/PCU
RNC
BTS
NodeB
GGSNCG
MVNO
MNO
4.2.11 UESBI-Iu
The UEs may have potential standard or manufacture defects. The RAN needs UE-specific
behavior information (UESBI) regarding 3GPP features to help the lower layer process the
local 3GPP features.
The UESBI corresponds to the following two sets of information:
UESBI-Uu: The messages are sent by the UE to the RAN through the messages defined
by the Radio Resource Control (RCC) protocol.
UESBI-Iu: The message is obtained by the CN from the International Mobile Station
Equipment Identity and Software Version number (IMEISV) of the UE. The CN then
sends the messages to the RAN through the Iu interface.
Figure 4-11 shows the network structure of the UESBI-Iu.
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Figure 4-11 Network structure of the UESBIIu
IMEISVUE
SGSNSRNCNodeB
1Attach and IMEISVinterrogation
IMEISVStorage
2
UESBI
3
MSC
When the UE accesses the VLR or SGSN, the IMEISV from the UE is saved in the VLR or
SGSN. When an Iu connection (such as CS voice session and PS data transfer) is set up later,
the IMEISV is read from the MM context of the VLR or SGSN to obtain the UESBI. The
UESBI is then sent to the serving RNC (SRNC).
4.2.12 Multi-SPs and 2 Mbit/s Signaling Links
Ever increasing equipment capacity boosts the signaling flow between signaling points. The
16 signaling links specified by the protocol are far from enough to fulfill actual networking
requirements.
To solve this problem, the SGSN9810 provides the multiple signaling points (multi-SPs)
function and 2 Mbit/s signaling links.
Multi-SPs Function
The SGSN9810 entity can be divided virtually into several logical signaling points. Thus the
restriction of 16 signaling links between two signaling points is broken.
As shown in Figure 4-12, from the aspect of other signaling points, the SGSN9810 contains
multiple signaling points, and there are 16 links for each signaling point.
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Figure 4-12 Multiple signaling points supported by the SGSN9810
SP SP
Single SP
Multi SPs
Link
Link Set
LinkLink Set
LinkLink Set
SP
SP2
SP1
2 Mbit/s Signaling Links
A 2 Mbit/s signaling link binds multiple timeslots into an E1/T1 link to increase the
throughput of a link.
4.2.13 NTP Client Functions
The network time protocol (NTP) is a TCP/IP protocol that is used to issue accurate time in
the entire IP network. Its transmission is based on the UDP. The RFC1305 specifies the
algorithm used by the NTP to ensure the accuracy of clock synchronization. Theoretically, the
accuracy can be 1 ns.
Figure 4-13 shows the synchronous networking mode of the NTP. The NTP time
synchronization can be realized provided that the network from the device or the lower server
to the upper server is available. The time accuracy offered by the NTP synchronous
networking mode is of ms. This can be applied in alarm, log, and performance measurement.
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Figure 4-13 NTP synchronous networking mode
NTP Server
NTP Server NTP Server
NTP Server NTP Server
NTP Server
NTP ClientNTP Client
Class 0
Class 1
Class 2
The NTP services can be classified into three types when the NTP synchronous networking
mode is used.
NTP server of the highest layer: It refers to the NTP server of stratum 0, which offers
time synchronization service to the lower layer.
NTP server of the intermediate layer: Stratum 1 and stratum 2 obtain time from the time
server of upper layer, and offer time synchronization to the lower layer.
NTP client: It only obtains time. Time synchronization service is not offered.
When the SGSN9810 is configured as the NTP client, it obtains time from the NTP server of
upper layer and synchronizes time. Figure 4-14 shows the networ