- PON Architecture for Wireless Backhaul October 28, 2009 Paul Wilford.

-

PON Architecture for Wireless Backhaul

October 28, 2009

Paul Wilford

2 | PON Architecture for Wireless Backhaul All Rights Reserved © Alcatel-Lucent 2009

The mobile backhaul problem 1


The mobile backhaul problem

Current Wireless Carrier Environment

Increased bandwidth demands

Due to more advanced users and handsets

Mobile broadband (killer app)

TDM Backhaul is not efficient for packet data

Doesn’t fit well in traditional T1 Architecture

Current Wireless Carrier Environment

Increased bandwidth demands

Due to more advanced users and handsets

Mobile broadband (killer app)

TDM Backhaul is not efficient for packet data

Doesn’t fit well in traditional T1 Architecture



Data is becoming the primary use of the network Data is becoming the primary use of the network


2005-2010 2010-20202000-2005

ARPUARPU

TrafficTraffic


New mobile data services require exponentially increasing bandwidth but generate less revenue per bit transported than voice services. 100 Kb/s for GSM GPRS (downlink)

≥100 Mb/s for LTE (downlink)

This will break the traditional voice-optimized TDM Mobile Backhaul (MBH) network

Legacy leased line capex and opex scale linearly with bandwidth

New mobile data services require exponentially increasing bandwidth but generate less revenue per bit transported than voice services. 100 Kb/s for GSM GPRS (downlink)

≥100 Mb/s for LTE (downlink)

This will break the traditional voice-optimized TDM Mobile Backhaul (MBH) network

Legacy leased line capex and opex scale linearly with bandwidth


Landscape of today 2


Landscape of today

3G1XHRPD

IP Channel BTS

Voice Channels

DoRNC

PDSN/HSGW

GSMUMTS

IP Channel

BaseStation

NodeB

Voice Channels

Separate Core Networks for different

Radio Access Networks

•SGSN – Serving GPRS Support Node

•GGSN – Gateway GPRS Support Node

•PDSN – Packet Data Support Node

•HSGW – HRPD Serving Gateway

•RNC – Radio Network Controller

•DoRNC – Data Optimized RNC

•BSC – Base Station Controller

•MSC – Mobile Switching Center

•HRPD – High Rate Packet Data (1xEV-DO)

BTS


Landscape of today

Examples of customer deployments – Customer ‘X’

Customer ‘X’ primarily uses ATM for backhaul. The overall strategy is to seek higher-capacity, lower-cost solutions as the more data-centric technologies such as HSDPA drive capacity requirements.

The target state architecture is one that is flexible and can scale as capacity demand increases. Some solutions being considered include fiber to the cell site and bonded copper.

Customer ‘X’ has a combination of GSM/UMTS networks and will need to integrate backhaul for all networks as it migrates from GSM to UMTS to LTE.


Landscape of today

Examples of customer deployments – Customer ‘Y’

Customer ‘Y’s backhaul strategy consists of delivering Ethernet over the existing copper infrastructure with a migration to fiber-based Ethernet backhaul services.

Customer ‘Y’ plans to leverage its Fiber to the Premise (FTTP) network with pseudowire to provide backhaul services.


Landscape of Tomorrow 3


Landscape of tomorrow – Evolution to a common core

GSMUMTS

IP Channel

BaseStation

NodeB

Voice Channels

3G1XHRPD

IP Channel BTS

Voice Channels

DoRNC

HSGW

MME PCRF

SGW

PDN GW

LTE

RNC

GSM and CDMA voice and data networks converge into an IP-based evolved packet core (EPC)

For LTE, IP data from the eNodeB connects directly to the EPC

BTS


Landscape of tomorrow - 4G/LTE Mission

High Peak Data Rates

100 Mbps DL (20 MHz, 2x2 MIMO)50 Mbps UL (20 MHz, 1x2)

High Peak Data Rates100 Mbps DL (20 MHz, 2x2 MIMO)

50 Mbps UL (20 MHz, 1x2)

Improved SpectrumEfficiency

3-4x HSPA Rel’6 in DL*2-3x HSPA Rel’6 in UL

1 bps/Hz broadcast

Improved SpectrumEfficiency

3-4x HSPA Rel’6 in DL*2-3x HSPA Rel’6 in UL

1 bps/Hz broadcast

Improved CellEdge Rates

3-4x HSPA Rel’6 in DL*2-3x HSPA Rel’6 in ULFull Broadband Coverage

Improved CellEdge Rates

3-4x HSPA Rel’6 in DL*2-3x HSPA Rel’6 in ULFull Broadband Coverage

Packet Domain OnlySimplified Network

Architecture

Packet Domain OnlySimplified Network

Architecture

Scalable Bandwidth1.4, 3, 5,

10, 15, 20 MHz

Scalable Bandwidth1.4, 3, 5,

10, 15, 20 MHz

Network Co-existenceUMTS, GSM, HRPD, CDMANetwork Co-existenceUMTS, GSM, HRPD, CDMA

Low Latency< 5ms User Plane (UE to RAN edge)

< 100ms camped to active< 50ms dormant to active

Low Latency< 5ms User Plane (UE to RAN edge)

< 100ms camped to active< 50ms dormant to active

*Assumes 2x2 for DL in LTE, but 1x2

for HSPA Rel’ 6

Radio Access Network

Core Network


Landscape of tomorrow – Technology Innovation

With increased spectral efficiency, reduced latency and increased bandwidth, LTE enables innovations to improve performance at the handset.

An example of this is CoMP.

With increased spectral efficiency, reduced latency and increased bandwidth, LTE enables innovations to improve performance at the handset.

An example of this is CoMP.


What is CoMP?4


What is CoMP? – Cooperative Multi-Point

Controller

High-speed backhaul

All signals are potentially useful – no interference!

Overcome inter-cell interference by coordinating Tx/Rx at several base stations, thereby greatly increasing user rates and system capacity.

Each user is connected to several bases

Desired signal

Desired signal

Interference

Data rates limited by interference

Each user is connected to a single base

Today’s network


What is CoMP? - System Outline

Base Station

Base Station

Base Station

Base Station

CoMP Processor

Backhaul that conveys both uplink and downlink baseband

signal.

Performs downlink and uplink CoMP beamforming.

Base stations communicate with a centralized CoMP processor. The backhaul network conveys both uplink and downlink signals.Base stations communicate with a centralized CoMP processor. The backhaul network conveys both uplink and downlink signals.

Handset

Handset

Handset

Handset


What is CoMP? – Coherent vs. Non-Coherent

Coherent

Uses I/Q samples for CoMP processing in time or frequency domain

Requires the highest bandwidth from the backhaul network

Potential for greatest gain at the handset

Non-coherent

Uses soft bits for CoMP processing

Requires less backhaul bandwidth than coherent scheme

Coherent

Uses I/Q samples for CoMP processing in time or frequency domain

Requires the highest bandwidth from the backhaul network

Potential for greatest gain at the handset

Non-coherent

Uses soft bits for CoMP processing

Requires less backhaul bandwidth than coherent scheme


What is CoMP? – Uplink and Downlink

Uplink

To perform uplink CoMP, I/Q samples or soft bits must be transmitted to the CoMP processor

Downlink

To perform downlink CoMP there are two options:

Data and beam forming coefficients sent to each base station

I/Q samples or soft bits sent to each base station

After CoMP processing performed at CoMP processor

The backhaul network must support the required data distribution to all nodes

Channel State Information is required for beam forming

Different base stations adjust the amplitude and phase of the transmission of the signals to the handsets to achieve improved handset performance

Uplink

To perform uplink CoMP, I/Q samples or soft bits must be transmitted to the CoMP processor

Downlink

To perform downlink CoMP there are two options:

Data and beam forming coefficients sent to each base station

I/Q samples or soft bits sent to each base station

After CoMP processing performed at CoMP processor

The backhaul network must support the required data distribution to all nodes

Channel State Information is required for beam forming

Different base stations adjust the amplitude and phase of the transmission of the signals to the handsets to achieve improved handset performance


What is CoMP? - Requirements

CoMP schemes demand for

High bandwidth

multiple Gbit/s (DL &UL coherent, time domain)

<1 Gbit/s (DL & UL coherent, frequency domain)

about 100 Mbit/s (non-coherent)

Low latency

about 1 ms (all schemes, optimal case)

high backhaul latency may become a show stopper for CoMP– Need for a backhaul solution that is low latency

The Technical challenge is to meet the latency requirement under fully loaded conditions. This requires sophisticated scheduling and MAC Layer processing.


Different PON technologies5


Different PON technologies

PON technologies:

APON – ATM PON

First PON standard – used primarily for business applications

622 Mbps/155 Mbps

BPON – Broadband PON

Extension of APON – added OMCI (OAM Management Control Interface) and WDM capability

622 Mbps/155 Mbps

GEPON/EPON – Ethernet PON

IEEE 802.3ah Standard

1Gbps/1Gbps

GPON – Gigabit PON

ITU-T G.984 Standard

Evolution of BPON

2.5Gbps/1.25Gbps


Different PON technologies

PON technologies:

10G EPON – 10G Ethernet PON

Extension of GE/EPON

10 Gbps/1 Gbps

XGPON – 10G GPON

Extension of GPON

XGPON1 – 10 Gbps/2.5 Gbps

XGPON2 – 10 Gbps/10 Gbps

GPON is a suitable backhaul technology for packet-based services

For increased capacity and to support applications like CoMP, XGPON2 is the

best backhaul solution


Synchronization6


Synchronization: Problems with synchronization

Base station radio interface typically requires some level of synchronization

Frequency accuracy

Time/phase accuracy

Base station backhaul interface (typically legacy base stations) may be synchronous (T1/E1)

Synchronization considerations

Relative phase stability

Mobile hand-off between base stations

Coherent CoMP

Core network may or may not be synchronous

(Traditional) Ethernet, Synchronous Ethernet, SONET, etc.

Separate timing distribution network may or may not exist

GPS, NTR, etc.

Base station radio interface typically requires some level of synchronization

Frequency accuracy

Time/phase accuracy

Base station backhaul interface (typically legacy base stations) may be synchronous (T1/E1)

Synchronization considerations

Relative phase stability

Mobile hand-off between base stations

Coherent CoMP

Core network may or may not be synchronous

(Traditional) Ethernet, Synchronous Ethernet, SONET, etc.

Separate timing distribution network may or may not exist

GPS, NTR, etc.


Synchronization: GPON Mobile Backhaul End-to-End Synchronization

OLTOLT

GPON

RNCBSC

RNC/BSCGateway

IP/ Ethernet Network

GPON-fed cell site gateway (ONU)

Cell site

E1, Eth

GPON PHY 8 kHz clockE1/Sync E

PRC PRC

IEEE 1588v2 (when PRC not avail. at OLT)

E1, Eth

The GPON Transmission Convergence (GTC) layer supports the transport of an 8 kHz clock via 125 microsecond framing

Therefore GPON provides deterministic synchronization like TDM

However, CoMP requires something better

To achieve more precise timing synchronization, provisions must be made to compensate for the OLT-ONU delay variations

The GPON Transmission Convergence (GTC) layer supports the transport of an 8 kHz clock via 125 microsecond framing

Therefore GPON provides deterministic synchronization like TDM

However, CoMP requires something better

To achieve more precise timing synchronization, provisions must be made to compensate for the OLT-ONU delay variations

OLT

ONU

ONU

ONUGPON frame t

t

t

t

GPON frame

GPON frame

GPON frame


The MAC Layer7


The MAC Layer: GPON

GPON QoS is maintained through transmission containers (T-CONTs)

T-CONT classes

Type 1 – fixed bandwidth

Type 2 – assured bandwidth

Type 3 – allocated bandwidth + non-assured bandwidth

Type 4 – best effort

Type 5 – superset of all of the above

Scheduling algorithm at the GEM Layer guarantees that transmission container bandwidth and latency guarantees are satisfied under fully loaded conditions

Dynamic Bandwidth Allocation

Maximum fiber bandwidth utilization

Based on queue status from ONUs

Security (via AES)

FEC

GPON QoS is maintained through transmission containers (T-CONTs)

T-CONT classes

Type 1 – fixed bandwidth

Type 2 – assured bandwidth

Type 3 – allocated bandwidth + non-assured bandwidth

Type 4 – best effort

Type 5 – superset of all of the above

Scheduling algorithm at the GEM Layer guarantees that transmission container bandwidth and latency guarantees are satisfied under fully loaded conditions

Dynamic Bandwidth Allocation

Maximum fiber bandwidth utilization

Based on queue status from ONUs

Security (via AES)

FEC


The MAC Layer: Backhaul challenges

CoMP data processed and sent to downstream path for scheduling/reflection to ONUs

Very low latency requirement of 1 ms

Handoff between eNodeBs requires tighter synchronization at base stations

OLT must send additional information to ONUs so they know neighboring ONU timing for handoffs

FEC at 10 Gbps

Completing R-S computations for 10 Gbps within 125 us is challenging

CoMP data processed and sent to downstream path for scheduling/reflection to ONUs

Very low latency requirement of 1 ms

Handoff between eNodeBs requires tighter synchronization at base stations

OLT must send additional information to ONUs so they know neighboring ONU timing for handoffs

FEC at 10 Gbps

Completing R-S computations for 10 Gbps within 125 us is challenging


The MAC Layer:

BWMap(Dual Port)

MAC CORE

Processor I/F

GEM LayerDownstream

(encapsulation)

TC LayerDownstream

AESEncryption

FECEncode

PHY Layer Downstream

GEM LayerUpstream

TC LayerUpstream

FECDecode

PHY LayerUpstream

PLOAMDownstream

PLOAMUpstream

Regs

I/O Macro

I/O Macro

I/O Macro

I/O Macro

I/O I/O

I/O Macro

PLSUpstream

DBRUpstream

North Bound

I/F

South Bound

I/F

Scheduling for QoS and CoMP reflection

CoMP processing. Data fed to downstream GEM Layer

for reflection to ONUs

S1/X2 translation

S1/X2 translation 10G FEC decode

10G FEC encodeCoMP timing messages


Conclusions8


Conclusions

XGPON2:

Is a backhaul solution that can accommodate growth in bandwidth demand

Is a backhaul solution that connects to the simplified network architecture

Is a backhaul solution that can integrate data from 2G,3G and LTE networks

Is a backhaul solution that can handle the uplink and downlink data

distribution requirements for applications like CoMP

Is a backhaul solution that is synchronous and is compatible with IEEE

1588v2 synchronization through packet networks

Is a backhaul solution that contains efficient scheduling in the MAC layer for

maintaining QoS under fully loaded conditions


Thank You!


Backup Slides


The MAC Layer: ONU block diagram

BWMap(Dual Port)

Processor I/F

PHY LayerDownstream

TC LayerDownstream

AES Decryption

FECDecode

PHY LayerUpstream

TC LayerUpstream

FECEncode

GEM LayerUpstream

PLOAMFIFODS

Regs

I/O Macro10G

I/O Macro

MAC CORE

GEM LayerDownstream

PLOAMFIFOUS

I/OMacro(s)

I/O Macro

I/O Macro

USER I/FTranslation

USER I/FTranslation

I/O I/O


SHDSL.bisSHDSL.bis

GPONGPON

0,512

4

8

10

24

100

> 1000

500

1

DL

Sp

eed

[M

bp

s]

2000

2002

2004

2006

2008

2010

2012

GPRS

UMTSWireless

10G PON10G PON

ADSL

ADSL

ADSL2ADSL2

Wireline

HSPAHSPA

Conclusions: Broadband Access Networks can support 3G/LTE Bandwidth Requirements

LTELTE

ADSL2+ADSL2+

VDSL2VDSL2

HSPA+HSPA+

GPON satisfies LTE bandwidth needs

• 2.5G DS/1.25G US shared

• Optical split adjusted as required.

• Future evolution to 10G PON (λ overlay on same PON)

Bonded VDSL2 supports HSPA+ and early LTE

ADSL2+ and SHDSL.bis are tactical solutions for 2G 3G

XGPON2 satisfies LTE bandwidth needs

• 10G DS/10G US shared

- PON Architecture for Wireless Backhaul October 28, 2009 Paul Wilford.

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Transcript of - PON Architecture for Wireless Backhaul October 28, 2009 Paul Wilford.