Anritsu Handheld Products For Testing CPRI

Anritsu Handheld ProductsFor Testing CPRI

November 2016

José María Pindado Buendía

Engineering & Technology, EMEA

Copyright© ANRITSU2

Agenda

• Introduction• C-RAN Technology Overview• Tests required and solutions for CPRI Network

– Optical Test– CPRI Test– RFoCPRI Test

• Summary

MT1000A/MT1100A Training FY 2015

3 Copyright© ANRITSU| CONFIDENTIAL |

Mobile operator challenges migration to C-RAN

• Operators are having to support an explosive spread of smartphones and tablets thus increasing demand for bandwidth, several challenges present to them:• Increasing Quality, bandwidth and coverage of the

communication• cost optimisation. The Euro per bit continues to decrease• To be prepare network next generation, the 5G• Reduce Energy consumption

• Adoption of Centralized-Radio Access Networks (C-RAN) is key for operators to achieve mobile network migration.

• New protocols are used over C-RAN• Common Public Radio Interface (CPRI) • Open Base Station Architecture Initiative (OBSAI)

Traffic (EB / Month) 2014 2019 GrowthFixed/Wired 32.4 55.7 11%Fixed/Wi-Fi 24.9 88.1 29%Mobile/Cellular 2.5 24.3 57%


Agenda



• Summary


5

Tower Evolution N

ode B

PS

AC

.

Switch

RRH

BB

U

PS

A\C

Switch

RRH

PS

A\CSwitch

RRH

PS

A\CSwitch

RRH

PS

A\CSwitch

RRH

4 P

ort

B

BU

Switch

PS

A\C

Heavy high loss Coax

Dedicated equipment high

Power consumption

Remote Radio

Head Unit

Optical Fiber and

Power feed

Less equipment lower Power consumption

Minimum equipment lowest

Power consumption

Single BBU serving multiple

RRH Units.

The migration to C-RAN

Yesterdays network

Todays networkRRH

Deployment

Tomorrows networkC-RAN

OTN / MPLS-TP

Metro Network

Current Transport Network

1 Gbps or 10 Gbps

Ethernet link

Ethernet / SDH/SONET

/ OTNNetwork

PS : Power SupplyAC : Air Conditioner

BBU : Base Band UnitRRH : Radio Remote HeadC-RAN : Centralized-Radio Access Networks

BTS

RRHRRH

RRHRRH

RRHRRHRRHRRH RRHRRH

6 Copyright© ANRITSU

What is CPRI

CPRI is digital interface standards for transmitting digitized RF signals from RRH to BBU.It defines framing, coding, control, synchronisation …managing the up and down traffic.

• It’s standard developed in cooperation with several manufacturers Ericsson, Huawei, NEC, ALU and Nokia.

Today CPRI interfaces are being deployed for RRH configuration.Tomorrow CPRI will be extended in the Mobile FrontHaul, some trials are done with the operators

.

CPRI

7

Mobile networks, CPRI where they fit IN

• This move to the C-RAN creates a new domain within the mobile network. • The new network between the BBU and the RRH in the cell site is referred to as the

fronthaul network• The network between the BBU and the core network is still the mobile backhaul

network – Physical layer, normally optical (electrical is standardized)

Mobile FronthaulMobile Backhaul

RRH: Remote Radio HeadBBU: Base Band UnitCO : Central Office

CPRI

CoreNetwork

Optical Link

8

BBU 4GBBU 4G

CWDM(up to 18 CPRI)

Passive opticalmux and Dmux

Active transponder

CPRI onDWDMNetwork

Active Front-HaulPassive Front-Haul

Distance between BBU and RRH relies on latency specification. The max distance is 40km.

Front Haul configuration

Distribution box

RRH

RRHRRH

RRH

RRHRRH

Ant up 1

RRH

RRHRRH

BBUBBU

BBU 3GBBU 3GAnt up 1

RRH

RRHRRH


CPRI System Architecture

(The CPRI standard uses other names, RU (Radio Unit)= RRH & DU (Digital Unit) =BBU

C&M : Control and Management


CPRI (option 1) basic frame structure (128 bits)

The basic frame is Tc = 1/fc, Tc = 1/3.84 MHz, = 260.417n

CPRI System architecture

11

• The Hyperframe– 256 basic frames

• 256 control words (the green section is the control words) organized in 64 sub channels, 4 words each.

– 66.67 µs (256*260.417) long• The CPRI (or eNodeB) Frame

– 150 hyperframes– 10 ms (66.67*150) long

• BFN (NodeB Frame Number)

The CPRI 10 ms Frame

#0 #Z #149CPRI 10ms Frame

#0 #X #255

1...8

B0

B = T-1

W

Y

Hyperframe

BFNMany NodeB Frames


CPRI rate and capability

• CPRI link capacity per option


CPRI capacity vs Radio format

Required CPRI link capacity depending on radio technologies


• Rates 1 through 7 use 8B/10B line coding

• New rates (7A, 8 & 9) use 64B/66B line coding

• Option/Line Rate 7A will be used for Machine to Machine(internal)• Don’t need to worry about for our

testing• Option/Line rate 8 = 10137.6 Mbit/s• Option/Line rate 9 = 12165.12 Mbit/s• Option/Line rate 10 = 24330.24 Mbit/s

CPRI Bit Rates increase

Option / Line Rate

Bit Rate (Gbps) Line Code

1 0.6144 8B/10B2 1.2288 8B/10B3 2.4576 8B/10B

4 3.0720 8B/10B5 4.9152 8B/10B6 6.1440 8B/10B7 9.8304 8B/10B

7a 8.1101 64B/66B8 10.1376 64B/66B9 12.1651 64B/66B

10 24.3302 64B/66B


Agenda



• Summary


16

C-RAN network is optical :

Many fibers Multi Mode and Single Mode- Fibers from RRH to cabinet, some tens of

meter - Cabinet to BBU some hundreds of meter

(<40km)

Many connectors Mainly LC type

Many transceivers SFP- Several types:

- Black and white- Colored- Single or two fibers

Mux and Demux (active or passive)

C-RAN network and Optical devices

RRH

RRHRRH

Distribution at bottonof the antenna

RRH

RRHRRH

Ant up 1

BBUBBU

Distribution insideBBU building

17

Depending on the operators, the procedure to test the optical network can be slightly different.

Installation and maintenance : tests are required• Connector cleaning• Fiber Characterization• Optical power and budget• Fiber identification

Tools are also required :• Microscope (a Visual inspection Probe)• Optical Time Domain Reflectometer (OTDR)• Power Meter & Optical Loss Test set (OLTS)• Visual Light source (VLS)

Optical tests for installation & Maintenance

18

RRH

BBU

RRH

CabinetDistribution

LC connectors

LC to LCconnectors

Tens ofmeters

<40km

Using an OTDR It tests the optical link (fiber + connectors)

Capable to measure fibers and to find some events on optical link : loss, reflection, bending, splice & connector

With the MT1000A OTDR :• FiberVisualizer mode : OTDR tests easy to understand with a

Pass/Fail evaluation

• OTDR mode : Usual visualization with trace and event table

• Multimode 850 and 1300nm and Singlemode 1310 and 1550nm

• Distance test range >> 40km

• Dead Zone : Event 0.8m , Attenuation 3.8m

19

Using Visual Inspection Probe VIP

G0306A Video Inspection Probe

Cleanup

Cleanup

A simple dust onto a connector can stop the optical link.

VIP tests ensure the connectors are clean.

Anritsu VIP can be connected on the MT1000A or a PC • Function for detecting presence of scratches and dirt on optical connector• Displays results as Pass/Fail evaluation based on IEC61300-3-35 standard• Supports various connector types

20

Using OLTS (Optical Loss Test Set)

With the MT1000A or CMA5

• Source: Multimode 850 and 1300nm and Singlemode 1310 and 1550nm

• ~50dB dynamic

• With MT1000A

• Measurement results managed with Loss Table

• Pass/Fail evaluation using preset threshold values

RRH

RRH

Tens ofmeters

It tests the optical link (fiber + connectors) For short distance & Quick tests

NOT able to find events on the distance

Loop is required if tests are done at the bottom of the antenna

CMA5source

CMA5PowerMeter

CMA5OLTS

MT1000A OLTS

21

VFL OPM

Using Visual Fault Locator (VFL)& Optical Power Meter (OPM)

Many Fibers and connectors to be linked at the right place. • Visually the VFL ensures the right connection• The OPM ensures the power level is enough

With the MT1000A• VFL, Emitting Red light. Modulate On/Off• Optical Power Meter -67 to +6dBm @ 800 to 1700nm

22

Anritsu solution : MT1000A

9” high-resolution

touch panel

Power switch

Tests covered:

- OTDR MM and SM

- Visible source

- Power meter

- Visual Inspection Probe

- OLTS

Visible Light Source Option

Back panel Cover

OTDR ModuleMU100020A/21A

Main FrameMT1000A

Optical Power Meter

OTDR Multimode Port (850/1300 nm)

OTDR Single-Mode Port (1310/1550 nm)

Audio AUX(Interface for GPS)

Clock Input

USBMini-B

USB A

USB A

Ethernet Interface (for Remote Control)

DC Input (18 Vdc)


Agenda



• Summary


24

C-RAN network and CPRI protocol

C-RAN network uses frames between BBU and RRH.

• Transmission section– Physical layer, normally optical (electrical is standardized)

• Bit rate and 8B/10B line coding or 64B/66B line coding– Standard requires transmission error

free at a rate of BER < 10-12

• Time Division Multiplexing section– Aligns each higher layer to

“time on the wire”

• Layer 2:– Control word:

• L1 In-band protocol• C&M data• Vendor Specific data

– IQ Data (RF data)

Laye

r 2La

yer 1

IQ D

ata

User Plane

Vend

or S

peci

fic

Eth

erne

t

Control & Management Plane SYNC

Electrical Transmission

Optical Transmission

Time Division Multiplexing

HD

LC

L1 In

-ban

d Pr

otoc

ol

C&M : Control & Management

Frame

RRH

RRHRRH

RRH

RRHRRH

Ant up 1

BBUBBU

Frame

25

L1-InBand CPRI protocol

Extract from Figure 30 in CPRI Specification V6.1: Start-up states

and transitions

Standby

L1 synchronization

Protocol setup

C/M plane (L2+) setup

Interface and vendor specific

negotiation

Operation

Passive link

No C&M

C&M proposed

A

B

C

D

E

F

G

State

C&M Control & Management

RF signal is carried into the payload of the frame.

Before carrying RF signal, the L1-InBand protocol establishes the connection between equipment.

Standby to Operation sequence allows to connect the equipment.

Alarms and Errors are reported in case the sequence failed:• LOS : Loss of Signal • LOF :Loss of Frame • Reset : Master send Reset to Slave• RDI : Remote Default Indication• SDI : SAP Default Indication

Frame

RRH

RRHRRH

RRH

RRHRRH

Ant up 1

BBUBBU

Frame

26

Transport CPRI - What’s tested and why• Testing up to the “Passive Link” (or to the “G” state)

– Allows to confirm that that BBU and RRH communication is OK• Optical power, wavelength (correct SFP), frequency, etc...• Confirms L1In-band sequence and show Alarm/error

• BERT (May require loopback)– Ensures network meets the required <10-12 requirement

The payload is filling in PRBS sequence (instead of RF)

• Delay (Requires loopback)– Ensures the minimum delayspecification in C-RAN is met

• Automatic Protection switching– For protected network, ensures theAPS sequences works correctly

①②

Tester

27

CPRI - Test cases for Installation and Maintenance

• Test case 1– Connect to actual Equipment

• SFP & frequency tests• Monitor Errors/alarms/link• Check equipment behaviour

• Test case 2– Terminate both sides of the transmission line

(one side could be in loopback)• BER test• Delay measurement• APS (Automatic Protection switching)

• Test case 3– Monitoring of the actual line between

BBU and RRH• Utilizing through mode to monitor interactive

behaviour of equipment

Test case 2

Test case 3

Test case 1

Splitter

Splitter

Monitoring situationOnly for Maintenance

Emulation test situation

System test situation

Tester

Tester

Tester Tester

RRH

BBU

RRH BBU

Tester

Tester

C-RAN

Tester LoopC-RAN

28

MT1000A Tester for TransportCPRI Product Features

CPRI/OBSAI L1 Test• Supported bit rates

– CPRI: 614.4, 1228.8, 2457.6, 3072.0, 4915.2, 6144.0, 9830.4, 10137.6 Mbps

– OBSAI: 768, 1536, 3072.0, 6144.0 Mbps• Clocks: Internal, External (10 MHz), GPS• Level (dBm), Bit rate and deviation (ppm) tests• Alarm/Error detection (Signal Loss, PSL, Pattern Error)• Unframed BER measurement• Automatic Protection Switching (APS) tests

MT1000A

BBU

BBU

SFP

BBU

RRU

SFP

Two ports, - Independent Generator/analyzer- Pass-through monitoring

Select the bit rate

Status & frequency tests

Alarm, error,statistics

APS tests, Switching time depending on events

29

MT1000A Tester for TransportCPR Product Features

• CPRI L2 Test– Link status monitoring– Alarm/Error detection (Signal Loss, LOS, LOF, R-LOS, R-LOF, RAI, SDI, Reset, PSL, LCV, INVSH, Pattern Error)– Framed BER measurement– Round Trip Delay RTD Measurement (min, avg, max)

LINK?EthernetHDLC

BBU

BBU

SFP

BBU

CPRI link configuration CPRI link status

30

MT1000A Tester for TransportOTN /CPRI Product Features

Several vendors use Optical Transport Network (OTN) to transport CPRI .Specific OTN tests are required at this layer:

– OTN Alarm/Error detection– L1 Unframed BER measurement using CPRI client signals


Agenda



• Summary



Typical test configuration for CPRI RF testing

80% / 20%or

50% / 50%

or

CPRI link


CPRI based measurements

• Differences with Traditional RF

• Configuring CPRI Link

RF CPRI

Analog Digital

Absolute Measurements Relative Measurements

dBm dB

Specific Center Frequency Base Band 0 Hz

Absolute Power levels Relative Power Levels

Full Span capable Max Span: Carrier BW +50%

CPRI Link

Key CPRI Parameters

Line Rate (rates 1 to 7 supported)

AxC (Antenna Container: 0 to 10)

CPRI BW (Bandwidth of LTE carrier)

IQ Bit Width (10, 12, 15, 16)

Reserve / Stuffing Bits (0 to 10)

Aggregation (On / Off)

Note: Configurations can be different on UL & DL


CPRI digital filtering - Limitations for Interference Hunting

LTEUplink

Nearby Transmitter

Pre-filter Frequency Range

Digital Filter

LTEUplink

Carrier BW + 50%

Traditional filtering

CPRI Digital Filter Only Tx Carrier IQ

CPRI based Interference Testing

In-Band only

CPRI Link

RRH

BBU


How to connect the instrument to the RRH/BBU

BBU

Optical TAP

A B AB

BBU

RRU

BBU

RRU

BBU

BTS

Mas

ter

RRU

Normal RRU to BBUConnection

Measures with Live Traffic

RRU

SFP

SFP

SFP

BBU


Layer 2 Alarms

BTS Master (2 SFP Ports)E series (1 SFP Port) MT1000A (2 SFP Ports)

SFP monitoring and alarm monitoring

Loss of Signal (LOS)Loss of Frame (LOF)LSS (Loss Sequence Synchronization)




SFP Data

BTS Master (2 SFP Ports)E series (1 SFP Port) MT1000A (2 SFP Ports)


CPRI spectrogram screen

• Spectrum and / or Spectrogram is useful for intermittent signals

• Use the spectrogram to look for signals that change over time• Unstable regarding frequency

and / or level

• Passive Intermodulation

• From a cell phone booster with insufficient input to output isolation

• Common consumer grade equipment issue

• Temperature sensitive

• Sensitive to changing reflections

• People

• Cars

• etc…


CPRI data


Agenda



• Summary


41

Summary

New challenges in the telecoms, the Mobile Network architecture will migrate using new technologies such as C-RAN and CPRI.

RF signal digitized as close as possible to RF antenna. The framed signal transmits information into the FrontHaul, BackHaul, and Core networks.

New network equipment to be installed for Mobile networks, vendors and operators have already done some trials.

Installation & Maintenance of these new network technologies require new procedures and testers.

Anritsu, leader in the instrumentation market, offers testers for optical link, CPRI protocol and RFoCPRI.

42| CONFIDENTIAL |

PM1-1SN150067-00

OTDR +CPRIOTDR +CPRI+ RFoCPRI Test

Anritsu is the only supplier that can cover all mobile network testing needs.Mobile Network Market

Network MasterPTP/SyncE

RFoCPRI +RFoCPRI +RF Test

NetworkMaster

BTSMaster

Questions?

Additional information


L1 Inband protocol• LOS

– Detection: 8B/10B or 64B/66B line coding errorsor low optical power level

– Action: Change to state “B” of the start-up process

• LOF– Detection: Hyperframe alignment isn’t possible– Action: Change to state “B” of start-up

process (RRH prevent emission “recommended”)

• Reset– Action: Sent from any master to

slave port, forwarded from slave to master (daisy chained) Extract from Figure 30

in CPRI Specification V6.1: Start-up states

and transitions

Standby

L1 synchronization

Protocol setup


Interface and vendor specific negotiation

Operation

Passive link

No C&M

C&M proposed

A

B

C

D

E

F

G

State


L1 Inband protocol• RAI

– Detection: Any CPRI transceiver errors LOS, LOF etc.

– Action on Remote: Change to state “B” of start-up process (RRH prevent emission “recommended”)

• SDI– Detection: Near end informing far end

equipment – link must not be used for any Service Access Points

– Action on Remote: Far end must not use the link anymore (RRH prevent emission “recommended”) Extract from Figure 30

in CPRI Specification V6.1: Start-up states

and transitions

Standby

L1 synchronization

Protocol setup


Interface and vendor specific negotiation

Operation

Passive link

No C&M

C&M proposed

A

B

C

D

E

F

G

State

Anritsu Handheld Products For Testing CPRI

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