telecom italia - wcdma ran ip back hauling - tim network architecture and synchronization aspects

8/3/2019 Telecom Italia - WCDMA RAN IP Back Hauling - TIM Network Architecture and Synchronization Aspects

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Rome 3-5 Nov 2009 2

Agenda

Synchronization in 3G

Radio Access Network Iub interface evolution

from ATM to IP

Iub over IP andsynchronizationsolutions

A.Guerrieri TIM WCDMA RAN IP Backhauling


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A.Guerrieri TIM WCDMA RAN IP BackhaulingRome 3-5 Nov 2009 3

Synchronization in 3G Radio Access Network

RNC

MSC

SGSN

MGWRBS

Radio Access Network Core Network

Uu

Iub Iu

Radio Interface

SynchronizationFrame

Synchronization

NodeSynchronization

Network

Synchronization

frequency error

< 50 ppb


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Network Synchronization is responsible for the distribution of clocks, and allowsthe clocks to operate at the same frequency in different nodes. Note that clockin this context does not deal with the time of day, but with frequency only.

Node Synchronization is the basis for the numbering of frames between theRNC and RBS nodes, and for frame timing. The correct operation of Node

Synchronization is dependent on the proper operation of NetworkSynchronization.

Frame Synchronization is responsible for the numbering of user frames, and forthe transmission and reception of frames to and from the RNC node at thecorrect times, to compensate for transfer and processing delay in the RNC-RBSpath. The correct operation of Frame Synchronization in the Intra-RNS case isdependent on the proper operation of the Node Synchronization.

Radio Interface Synchronization is responsible for the alignment of radio framesbetween the RBS and the UE.

Synchronization in 3G Radio Access Network


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Rome 3-5 Nov 2009 5

Iub interface

evolutionin TIM

Radio AccessNetwork



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Iub Interface over ATM: the 3GPP Standard

Node B

Application Part

(NBAP)

AAL Type 2

ALCAP

Transport

Layer

Physical Layer

Radio

Network

Layer

Radio Network

Control Plane

Transport

NetworkControl Plane

DCH

FP

RACH

FP

ATM

DSCH

FP

AAL Type 5

User Plane

SSCF-UNI

SSCOP

AAL Type 5

SSCF-UNI

SSCOP

Q.2630.1

Q.2150.2

FACH

FP

PCH

FP

USCH

FP

CPCH

FP

TFCI2FP

Radio LayerProtocols

Transport LayerProtocols (TNL)

ALCAP protocol stack: for AAL2 connections setup


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RAN Reference architecture before 2005

BTS

BTS

MGW

MSC

SGSN

ATM SwBTS

BTS

Iub, Mub

Iub, Mub

UTRAN Core Network

RNC

Iu

Iub

ATM Sw

RNCIu

Iur

BTS

MGW

MSC

SGSN

BTS

BTS

Iub, Mub

BTS

Iub

ATM Sw

RNC

Iur

BTS

Iub

Iub

E1 Links

STM1 links(local)

Iu


ATM Sw

ATM Sw

SDH

SDH

SDH


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Common ITU-T specifications used

Specified by 3GPP

ATMAdaptation

Layer AAL2

A

AL0

A

AL5

PhysicalLayer

E1 - STM1 (PDH-SDH)

VP (Virtual Path)

ATM Layer

VC (Virtual Channel)

Radio Network Layer

Transport Network Layer

ATM Transport according to 3GPP R99

UTRAN Protocol layers - Iub over ATM

RadioApplication

Layer

WCDMARadio

ApplicationChannels



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Specified by 3GPP

ATMAdaptation

Layer AAL2

A

AL0

A

AL5

PhysicalLayer Electrical / Optical - GbE

VP (Virtual Path)ATM Layer


Radio Network Layer


RadioApplication

Layer

WCDMARadio

ApplicationChannels

Eth Layer PWE3 (Martini circuits) over Eth

UTRAN Protocol layers - ATM over Eth (generic)



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RAN Reference architecture after 2005

BTS

BTS

MGW

MSC

SGSN

ATM SwBTS

BTS

Iub, Mub

Iub, Mub

UTRAN Core Network

RNC

Iu

Iub

ATM Sw

RNCIu

IurOPM

GTW-A

GTW-A

BTS

GTW-B

MGW

MSC

SGSN

BTS

BTSIub, Mub

GTW-A

OPM GTW-B

BTS

Iub

ATM Sw

RNC

Iur

BTS

Iub

Iub

E1 Links

STM1 links(local)

Iu



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Iub over TI GbE backbone

OPM TI

(GbE)

RNC

E1

E1

GTW-A

E1

E1

GTW-A

GTW-B

RNC

Link E1

Link STM-1 VC 12

Link STM-1 VC 4

Ethernet

OSS

PWE3/Ethernet

ATM

ATMATM



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Iub (ATM) over GbE

NodeB

SOL SDH

nxE1 GBE

DWDM Infr. GBE

nxSTM1

SDH

3G

SDH

RNC

feeder

metro

8630 8840

ADM

ADM

Rete otticametropolitana OPM

Circuito ATM

VLAN per UMTS

PWE3 (Martini circuits)

GTW_AGTW_B

ModemSHDSL

ModemSHDSL

Centrale diattestazioneSOL

rame

metro

STM1CWDM CWDM



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Iub over IP



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Specified by 3GPP

ATMAdaptation

Layer AAL2

A

AL0

A

AL5

PhysicalLayer

Physical Connection (E1/E3/STM1)

VP (Virtual Path)

ATM Layer


Radio Network Layer



UTRAN Iub over ATM

RadioApplication

Layer

WCDMARadio

ApplicationChannels



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Specified by 3GPP

PhysicalLayer

Electrical / Optical (GbE)

Radio Network Layer



RadioApplication

Layer

WCDMARadio

ApplicationChannels

IPTransportLayer

UTRAN Iub over IP



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Iub over IP Protocol Stack

DCH, HS-DSCH, E-DCHFACH, PCH, RACH FPs

and Node Sync (overFACH)

NBAP

TransportNetworkLayer

RadioNetworkLayer

Radio NetworkControl Plane

Network Synch Radio NetworkUser Plane

NWSync

Ethernet

UDPSCTP (*)

NTP (**)

(*) SCTP (Stream Control Transmission Protocol)(**) NTP (Network Time Protocol )

Ethernet Ethernet

IPIP IP

UDP



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OPM

RNC

Eth

Eth

Eth

Eth

RNC

Link E1

Link STM-1 VC 12

Link STM-1 VC 4

Ethernet

OSS

IP IPIP

Eth

Eth

Iub over IP



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RNC

GE

NodeB

MetroFEEDER

1GE

1GE

SGUSite

RemoteFeeder

OpticalNetwork

DWDM ornaked fiber

1GE

METROdi raccolta

GE SLSite

GE

nakedfiber

Optical

Fiber

Ring

Iub over IP Architecture (FTTB)


1GE

10GE

10GE

10GE

10GEGE

OPMMETRO


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Rome 3-5 Nov 2009 19

OPMOptical Packed Metro

Layer 2 NetworkRNC

Eth

Eth

Eth

Iub over IP - Layer 3 Architecture

DCN(OSS)

RdG

MdR

MdR

RemoteFeeder

RemoteFeeder

RPS HSRP

HSRP

RSTP

Layer 3 connection Layer 3 connection

MdR = Def Gateway MdR = Def Gateway



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Synchronization

over IPsolution



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Network Synchronization over IP

Client - Server synchronization architecture.A Network Synch NTP Server is integrated inRNC and a client is in RBS

Synch - Server connection is based on NTPProtocol (Network Time Protocol) over UDP/IP

Network synchronization for an IP connectedRBS is achieved by aligning the frequency ofthe RBS to the frequency of an NTP serverwith traceability to a G.811 source.

RBSs are synchronized using ad hoc clockrecovery algorithm that uses NTP packets(OCXO in RBS)

No other synchronization functionalitiesrequired (external devices, Synch nodes, GPSetc.)


SASE

2 MHz GPS

Iu over IP/ETH Iu over ATM/SDH

SS

SC

Synchronization Server

Synchronization Client

SC SC

SS

NTP

IP/EthernetNetwork


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Network Sync details

RNCIub over IPSync

Client

Sync

Server

Timing

Unit

In order to meet performance requirements, the Synch Client sends an NTP request at regular intervals.

The regulator selects the NTP packet frequency based on its need. The range of 1-10 packets per second.

The higher request frequency is used at start-up or acquisition to make convergence time shorter, and thenwhen steady state is reached, the rate is decreased.

Iu overATM (SDH) CoreNetwork

In case Iu is connected only over IP, there will be no transmission interface available from which the RNC

can take its synchronization. In this case, the RNC must take its synchronization from the physical

synchronization port on its Timing Unit. The signal to this physical synchronization port can be e.g. a 2.044

MHz signal from a SASE, or from an SDH multiplexer on site

RNC

Iub over IPSyncClient

Sync

Server

Timing

Unit

Iu over IP

SASE

CoreNetwork


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Rome 3-5 Nov 2009 23

Iub over IP Network Synch Protocol Stack

DCH, HS-DSCH, E-DCHFACH, PCH, RACH FPs

and Node Sync (overFACH)

NBAP

TransportNetworkLayer

RadioNetworkLayer

Radio NetworkControl Plane

Network Synch Radio NetworkUser Plane

NWSync

Ethernet

UDPSCTP (*)

NTP (**)

(*) SCTP (Stream Control Transmission Protocol)(**) NTP (Network Time Protocol )

Ethernet Ethernet

IPIP IP

UDP



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Rome 3-5 Nov 2009 24

Backhauling requirements for Iub over IP

Service requirements: no additional requirement for the backhauling IPnetwork compared to the "ATM over GbE" solution.



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Backhauling requirements for Iub over IP


The max PDV is generally not a sufficient requirement for the

purpose of qualifying a packet network as able to carry timing

over packets.This is especially true in the definition of the start up

conditions: in this case the PDV statistics is fundamental (e.g.

in order to select a suitable number of good packets)

Current requirement in TIM network: when best 1% packetshave less than 20 microseconds delay variation, locking

happens quite fast (


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Rome 3-5 Nov 2009 26

TI Optical Packet Metro


24 MdR (Metro di Raccolta) 60 Metro 30 sites

70 Metro Feeder 180 Remote Feeder (180 SGU sites) OPM Load between Feeder and Metro: 5%-10% Number of nodes between Node B and RNC: 4 (Remote Feeder, Metro Feeder,Metro, MdR) OPM Traffic Handling: QoS priority (3 queues)

RNC

GE

NodeB

MetroFEEDER

1GE

1GE

SGU

Site

RemoteFeeder

OpticalNetwork

DWDM ornaked fiber

1GE

METROdi raccolta

GESL

Site

GE

naked

fiber

OpticalFiberRing

1GE

10GE

10GE

10GE

10GEGE

OPM

METRO

100 Node Bs active todayusing Iub over IP and opticalfiber FTTB with dedicated nakedfiber (no GPON) Project started in 1H 2008 Hundreds of Nobe B over IPplanned for 2009-2010 Very stable solution No synchronizationproblems


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QoS for Iub over IP

QoS separation at IP level, using DSCP (Differentiated Services CodePoints). [0...63].

QoS separation at Ethernet level by using the Priority Bits (L2 Ethernetpriority 802.1p). P-bit [0..7]

Bearer X

Bearer Y

Bearer Z

DSCPX

DSCPY

DSCPZ

P-BitX

P-BitY

P-BitZ



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QoS Mapping TIM choices

3 QoS Priority Levels

Maximum: Network Synchronization and Conversational/Streaming traffic Medium: PS R99 DCHs and NBAP signaling Best effort: HSDPA/HSUPA

Layer 3:

DSCP

Layer 2:

P-bit

High Priority46 Sync

18 CS & Stream

5

Sync, CS, Stream

Medium Priority22

PS R99, NBAP

3

PS R99, NBAP

Best Effort0

HSxPA

0

HSxPA

Our Optical Packed Metro is a Layer 2 network working with 3 P-bit values (5, 3, 0), so wehad to adapt the mapping of DSCP to P-bit to the existing situation.



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QoS Mapping TIM choices (2)

Layer 3:

DSCP

Layer 2:

P-bit

46 Sync

18 CS &Stream

5

Sync, CS,Stream

22

PS R99,NBAP

3

PS R99,NBAP

0

HSxPA

0

HSxPA



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Rome 3-5 Nov 2009 30

Conclusions

Iub over IP is the solution for: the transport bottlenecks removal the evolution of the network towards new services:

HSDPA Evolution 64QAM (up to 21 Mbps) HSDPA Evolution MIMO (up to 28 Mbps) HSDPA Evolution MultiCarrier (up to 42 Mbps)

LTE (150/300 Mbps)

Live traffic shows good performance and no quality, reliability orthroughput variations. Iub over IP (optical fiber) deployment started in 1H 2008 100 Node Bs active today using Iub over IP and optical fiber Hundreds of Nobe B over IP planned for 2009-2010 in the TIM RadioAccess Network


Iub over IP (with sync based on NTP over IP) is a very stable solution:no synchronization problems in real network (18 months)


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TIM A.Guerrieri TIM WCDMA RAN IP BackhaulingRome 3-5 Nov 2009 31

Acknowledgements:

Lorella Parmeggiani(TI Opical Packet Metro Engeniering)


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Thanks for

Your Attention

Alessandro Guerrieri

TIM Telecom Italia

Wireless Access Engineering

[email protected]

telecom italia - wcdma ran ip back hauling - tim network architecture and synchronization aspects

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