road to epc

7/27/2019 Road to EPC

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1 Copyright 2009 AIRCOM International

Evolution to LTE-EPCIstehsan Abbas


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Agenda

Core definition

Releases for Core

Per release explanation

Path towards SAE/ LTE

IMS and LTE

LTE Core description and detail of each

entity2


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Core Definition

CN includes physical entries realizing user location

management, network functions and service control eg;

MSC

HLR

STP

SMSC

GSN etc


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Evolution towards LTE

R-99

GSM with GSN

64 kbps CS, 384 kbps PS

Location services

R4

Split architecture

MMS

Improved location services

Basic IMS

R5

IMS advancements

IP transport in UTRAN

HSDPA

R6

WLAN integration

Multimedia broadcast

HSUPA

Improvements in IMS

R7MIMO smart antennas

PCRF

R8Introduction of LTE

EPC


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2.5G GSM networks (R99)

PSTN

VLR

HLR AUC EIR

VMSC GMSCBSCBTS

IP

backbone

GGSNSGSN

GPRS IP

backbone

PLMN

AAA DHCP

IN

CAMEL

DNS

With the upgrade to 2.5G network

IP Backbone is added for GPRS (SGSN/GGSN)

IP Network is also required for DNS, AAA, DHCP facilities

2G GSM networks (R96)

2G GSM Network consists of

CS/TDM MSCs

TDM/ATM based backbone


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AS

PSTN

3G R5/6/7/8, Ultimate Aim All IP

CSCF

MGWRNCNodeB

SGSN

IP

backhauling IPbackbone

GGSN

GPRS/VoIP IP

backbone

AAA DHCP

HSS

DNS


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Benefits of Split architecture

Introduction of Split Architecture in Core NW

Core Network

MSCs will be upgraded to MSC Servers.

Introduction of MGWs

Distributed switching

Saving of OPEX by saving LL Cost (No backhaul of voice to MSC-S)

Transport All IP

1 unified backbone for all networks

MPLS for end to end QoS


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Migration R99 to IP Cores


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R5 overview

CS/ PS Integrated IP networks

Both CS and PS passing through IP

Segregation at RNC (R5)


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LTE and onwards

Initial release

For 3G CS traffic Fallback was done

LTE traffic all converged to EPC

Traffic segregation at eNB


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Path towards R8 and IMS over LTE

CS and PS terminating on EPC

IMS based VoIP over LTE


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Summary of EVOLUTION


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Release overview


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Future Core networks

IMS

LTE


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LTE


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Performance Goals for LTE


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Introduction Demand of High bandwidth internet services like MMOG, mobile TV etc

Latest generation of technology also referred to as 4G

E-UTRAN (Evolved UMTS Terrestrial Radio Access NW) expected to improve:

End-user throughput

Sector capacity

Reduce user place latency

Full mobility, significantly improving the user experience.

End to End IP connectivity, enabling same QoS facility as that of IP

Voice traffic mainly supported on VoIP

Enabling integration with other multimedia devices more easily.

Unlike HSPA (UMTS), 3GPP specified a new Packet core, EPC.

Facilitating with lesser number of nodes, improved redundancy and seamless handover to other wireless/

fixed line technologies. (a seamless mobility exp)

Aggressive performance requirements, depending on physical layer technology such

as OFDM, MIMO, smart antennas.

Allowing flexible spectrum deployment in existing or new freq spectrum

Enabling existence with other 3GPP Radio access technologies (RATs)


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More interfaces

S101: Interface between MME and RNC for pre-registration andhence faster inter-system handovers. (signaling message shared

only). (two signaling i.e. 1- pre-registration and 2- HO signaling)

This way, we dont waste time for radio session initiation rather a simple radio

connection is done using the old radio session. (this process is referred to as pre-

registration)

S103: interface between SGW and PDSN (other 3gpp/ non 3GPP

technology) for forwarding the left over packets during the

handover process from LTE to other technologies. (mostly 3G)


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Roaming interface

S8: interface between SGW (visitor network) and P-GW (homenetwork) (concept almost the same as visitor SGSN connectivity

with home GGSN once you are in the roaming network)


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EPS


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EPC

Main elements are:

MME SGW

PGW

ePDG

PCRF


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Primary Difference between 3G and 4G Core

EPC is only packet switched Voice is traveled over IP (i.e. on Packet network)

EPC is an all IP Setup


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MME functions

Bearer Control

Managing and storing UE contexts

Distributing Paging messages to eNBs

Security Control

Authentication

Generating temporary identifiers to the UEs

Roaming

Tracking Area List management

Idle Mode UE tracking and reachability

Control and execution of paging

Serving GW selection

Mobility Management

For inter 3GPP access networks

For intra 3GPP access networks

Idle State mobility control

Lawful interception


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Functions of S-GW

Terminates user interface towards E-UTRAN

Packet routing and forwarding

IDLE mode DL packet buffering

Local Mobility Anchor for inter eNB Handover

Mobility anchoring for inter 3GPP mobility

Transport level packet marking in UL/DL

E.g Diffserv Code point, based on the QCI

Accounting for inter-operator charging

Event reporting (change of RAT etc.) to the PRCF

Lawful interception


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PDN NW GW (PGW)

Interface for UE towards Packet world (similar to GGSN)

A single UE may have multiple connections towards PGW

while accessing different PDNs

Functionalities of PGW are:

Policy enforcement

Packet filtering for each user

Charging support

Lawful interception Packet screening

Anchor of mobility between 3GPP and non 3GPP NWs


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ePDG (evolved Packet data gateway)

For the access of a UE from itself to untrusted non-3GPP access.S2b interface only.

Acts as a termination point for IPSEC from UE. (S2-b interface)

NOTE: S2a and S2c do not require ePDG, where S2a is towards the

trusted Non-3GPP access (towards a proxy Mobile IP) and S2c can be

trusted or untrusted access towards another client Mobile IP (and notproxy mobile IP)


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PCRF Works on DIAMETER protocol

Manages QoS aspects

On Gx interface, Policies are defined.

On Gy interface, Prepaid subscribers are charged

On Gz interface, Post-paid subscribers are charged

Gxx (which can be, Gxa towards IP-CAN or Gxc towards SGW) is purely for access to non 3GPP

technologies. (once roaming to them), triggered once S9 interface is under use (i.e. between

Visitor PCRF and Home PCRF)

Rx interface is for AAA (accounting, authentication and authorization) of subscriber.

Conceptually this is the first step before the policies are dictated to any particular subscriber.

Sy interface is for the subscription information of the subscriber.


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HSS

Same as HLR for SGSN, extra features added. HLR/AuC in one node

Repository for all subscriber/ service related features.

Interfaced with MME over S6a

3GPP Rel10 compliant

Seamless 3G-LTE mobility

Vo LTE support

Shared subs profile, context and state with ngHLR

Leverage HLR Proxy Mode to interwork with

Legacy HLRs

Supports Idle-mode

Signalling Reduction (ISP)

Integrated LTE-EIR


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