RRH-to-BBU Network Testing to
Ensure Performance and Reliability
Presenter:
Absolute Analysis
This presentation contains Proprietary Information.
Not intended for public distribution
Page 1
Agenda
• 1 – RAN Evolution and Test
Categories for RRH-To-BBU
Networks
• 2 - Investigator Product
Introduction
• 3 – Solving 5 Major 4G/LTE
RAN Problems
This presentation contains Proprietary Information.
Not intended for public distribution
Page 2
Presenter/Corporate Info
About Absolute Analysis
• Mission: Validate serial
communications
• In business since 1999
• Help customers test high
speed systems in:
About The Presenter
• Position
• Experience, etc.
– Telecom
– Military
– Data centers
• Fully employee owned
This presentation contains Proprietary Information.
Not intended for public distribution
Page 3
Presenter
Picture
LTE Radio Access Networks
Test Categories
• Interoperability: More
equipment, more problems
• RRH-BBU Communications:
Separation creates a difficult
debug environment
• RF Modulation Testing:
Validation of RF to Digital RF
• Performance Testing: Distance
requires more performance
testing of PON
• Multi-technology: Legacy +
4G/LTE creates complex timing
and cross-domain issues
This presentation contains Proprietary Information.
Not intended for public distribution
RRH
CPRI/
OBSAI
link
Interoperability
Multi-Technology
RF Modulation
Timing
Testing
BBU to RRH
Communications
Performance
Testing
BBU
DWDM
PON
Page 4
Visibility into the link is the key to
testing the RAN
CPRI or OBSAI Link
BBU
RRH
IQ Data
Command
Protocol
Vendor Specific
This presentation contains Proprietary Information.
Not intended for public distribution
Page 5
The #1 LTE Hardware Integration
Problem
WHERE is my problem?
RRH Team
BBU Team
Software Team
Hardware Team
RF Engineers
This presentation contains Proprietary Information.
Not intended for public distribution
DSP Engineers
Page 6
Section 2
INVESTIGATOR PRODUCT DESCRIPTION
RRH-TO-BBU COMMUNICATIONS TESTING
This presentation contains Proprietary Information.
Not intended for public distribution
Page 7
Who Uses Investigator?
This presentation contains Proprietary Information.
Not intended for public distribution
Page 8
A Comprehensive High-Speed Serial Protocol Test System
Investigator with mini-Portable
Chassis
This presentation contains Proprietary Information.
Not intended for public distribution
Page 9
• Monitor and Capture Data
• Real-time Performance
Statistics
• Decode IQ Data
• Decode C&M Data
• Generate CPRI and OBSAI
traffic
• Inject errors and delay
• BER Testing
• CPRI: 0.6144 to 6.144 Gbps
• OBSAI: 1.536, 3.072, and
6.144 Gbps
• Different Chassis Options
Network Connection Options
RRH
RRH
TAP
BBU
Optical Tap
BBU
Interpose Mode
RRH
BBU
This presentation contains Proprietary Information.
Not intended for public distribution
Cross Connect Switch
Page 10
Detailed Type of Testing
 Testing for Protocol Compliance
 Proper HFN, BFN incrementing
 Control word formatting
 Boot up sequence debugging
 RRH/BBU Control and Management
 When RRH receives command, what is it’s response?
And vice versa?
 What is the latency of any one device?
 RF Analysis
 Are my DPD algorithms working?
 Is the problem in my baseband IQ or my RRH
modulation?
 Stress Testing
 Inject errors via traffic generation
 Introduce delay into link
This presentation contains Proprietary Information.
Not intended for public distribution
Page 11
Compliance Testing – Sync and Timing
SYNC and Timing
• SYNC byte check
• HFN Increment, range
• BFN Increment, range
This presentation contains Proprietary Information.
Not intended for public distribution
Page 12
Compliance Testing – L1 Inband
•
•
Link Maintenance Flags
Vendor Specific Area
This presentation contains Proprietary Information.
Not intended for public distribution
Page 13
Extract IQ Data and Control Layer Data
Time: 10 40.040405
NPWR=300
MINOHPWR=230
MAXNUMCARR=8
MAXNUMPORTCARR=8
RRH
Spectrum Analyzer
Ethernet TCP
Commands
RF Software
CPRI /OBSAI
link
Fast C&M Data
(.PCAP or CSV)
Digital RF Data
(IQ) in CSV, text,
or MATLAB
BBU
This presentation contains Proprietary Information.
Not intended for public distribution
Page 14
Vendor Specific Channels
• Decode Vendor Specific Area
• C&M Decodes
This presentation contains Proprietary Information.
Not intended for public distribution
Page 15
Extract IQ Data
• From IQ Data, plot RF
using RF Analysis
software tools
Spectrum Graphs
Time Domain Graphs
This presentation contains Proprietary Information.
Not intended for public distribution
Constellation/EVM
Measurements
Page 16
Real-Time Performance Statistics
• Performance Statistics
– Loss of Signal (LOS)
– Loss of Frame (LOF)
– Service Port Access (SAP)
defect indication (SDI)
– Remote Alarm Indication
(RAI)
– Radio frame numbers
UMTS
• Protocol checks
– HFN/BFN sequence errors
– HFN range errors
– Invalid BFN numbers
This presentation contains Proprietary Information.
Not intended for public distribution
Page 17
Impairment (Delay and BER) Testing
• Simulate cable length delays
• Eliminates need to have
physical cabling to test
• Simulate fibre, coax, or twisted
pair
• Select cable length or delay
• Simulate BER from 10-9 to 10-15
• Specifications:
RRH
– Length: Cable length range:
2.4km to 40,000 km, resolution
7.6m
– Delay: 10uS to 1 second
BBU
This presentation contains Proprietary Information.
Not intended for public distribution
Page 18
Investigator for Laboratory
Applications
• Lab Testing Environment
– Protocol Analysis
– Real-Time Performance
Statistics
– Traffic Generation
– Error Injection
– Impairment (delay) testing
– Up to 16 CPRI or OBSAI
links
– Record up to 13 LTE radio
frames
This presentation contains Proprietary Information.
Not intended for public distribution
Page 19
Error Injector
• Inject errors into the
link to check error
recovery algorithms
• Checks include
– Setting link
maintenance flags
– Inserting CRC errors
This presentation contains Proprietary Information.
Not intended for public distribution
Page 20
Section 3
5 CASE STUDIES
RRH-TO-BBU COMMUNICATION PROBLEMS
This presentation contains Proprietary Information.
Not intended for public distribution
Page 21
1 – CPRI Byte Alignment
• CPRI Specification: Rules for
incrementing HFN and BFN
• Problem: If this is not correct,
interoperability problems
occur
• Solution: Use Performance
Statistics and Analyzer trace
capture to find any issues
This presentation contains Proprietary Information.
Not intended for public distribution
Page 22
1 – Solving Interoperability Example
HFN/BFN
incrementing
properly?
All CPRI/OBSAI
parameters
operating
according to
specification?
This presentation contains Proprietary Information.
Not intended for public distribution
Page 23
2 – Link Boot Up Solution
• Problem: On bootup, BBU
issued LOS intermittently. Link
would sometimes go down,
but not always.
• Solution: Capture link data
around LOS flag to see
conversation.
• Resolution: RRH was found to
go into frozen state on LOS
issue in complex timing patter.
This presentation contains Proprietary Information.
Not intended for public distribution
Page 24
3 – Fast C&M Visibility
• Problem: How to
check for command
layer stability
– Illegal Preamble
– Truncated frames
– Proper conversation
exchanges
• Solution: Capture
trace on C&M Layer
This presentation contains Proprietary Information.
Not intended for public distribution
Page 25
3 - RRH-BBU Communication Problems
Extract Fast C&M (Ethernet Channel) Data
Captured
Captured
Trace
Data
Trace Data
This presentation contains Proprietary Information.
Not intended for public distribution
CPRI/OBSAI
User Inputs
Data Extractor
Page 26
To Wireshark:
Ethernet
Command
Data (PCAP)
RRH/BBU C&M Layer Example
(TCP)
Time: 11 40.146655
Time: 10 40.040405
NPWR=300
MINOHPWR=230
MAXNUMCARR=8
MAXNUMPORTCARR=8
APCF=-15000
MASTERPORT=NO MASTERNUM=0
SLAVETCVR=RATE3
MASTERTCVR=NONE
LTECAP=0X0000003F HWTYPE="RRH" NUMTX=4
NUMRX=4 INFO=""
ADDLHW=NONE?EVENTENABLE:STATE=ENABLE?INTAL
MSTAT:INTALM=0X00200000,0X00000000
INTALM2=0X00000000,0X00000000
INTALM3=0X00000000,0X00000000?EXTALMSTAT:EXT
ALM=0X00000000?SIMULCAST:STATE=DISABLE?CPRID
ESC:NUMCPRIPORT=2 PORT1MODES=0X0000000
This presentation contains Proprietary Information.
Not intended for public distribution
Page 27
MESSAGE:TYPE=GETRESPONSE
TRANSACTION:ID=242
CPRISTAT:PORT1MODE=SLAVE
PORT2MODE=SLAVE
PORT1STATE=PASS
PORT2STATE=PASS
PORT1LNRATE=2
PORT2LNRATE=2
PORT1LNNEG=AUTO
PORT2LNNEG=AUTO
PORT1CMMODE=ACTIVE
PORT2CMMODE=ACTIVE
PORT1CMRATE=35
PORT2CMRATE=2
PORT1IQFMT=IQ16
4 – Rx Interference Problems
• Problem: Interference on
Rx signal causing dropped
calls
• Technical Headache: Signal
analyzer could not measure
exact RF radio horizon as
antenna
• Solution: Captured IQ data
on CPRI uplink
This presentation contains Proprietary Information.
Not intended for public distribution
Page 28
RRH
BBU
Traditional
Network
4 – Rx Interference Problems
RF to Digital RF (IQ) Correlation Test Set Up
CPRI/OBSAI Link
BBU
RRH
Investigator
CPRI/OBSAI Protocol
Analyzer
2 Way Trigger
60000
Signal Analyzer
40000
20000
-20000
IQ
Data
Correlated
This presentation contains Proprietary Information.
Not intended for public distribution
IQ
Data
Page 29
1
38
75
112
149
186
223
260
0
-40000
-60000
IQ Plots
5 - PON Performance Testing
• PON Problem:
Performance through
network did not meet
specification
• Technical Headache:
Did not know where
impairments were
• Solution: Used CPRI
and OBSAI
performance tester to
location slow devices.
This presentation contains Proprietary Information.
Not intended for public distribution
ROADM
BBU
BBU
BBU
BBU
BBU
Optical
Terminal
CPRI/OBSAI
Across WDM
(Distance to
50km)
ROADM
Baseband Pool
ROADM
Small Metro
Cells
Page 30
Macro Cells
RRHs
5 - PON Performance Testing
Performance Measurements
Find:
• Latency
• Failover delay
• Bit Error Rate
•
•
•
•
Cable disruptions
Slow devices
Misbehaving devices
Impairments
ROADM
Optical
Terminal
CPRI/OBSAI
Across WDM
(Distance to
50km)
ROADM
ROADM
Investigator for Baseband
side performance testing
Small Metro
Cells
This presentation contains Proprietary Information.
Not intended for public distribution
Page 31
Macro Cells
RRHs
5 - WDM Performance Testing
Primary
circuit
Optical
Terminal
Switch
Backup
circuit
ROADM
CPRI/OBSAI Across
WDM
(Distance to 50km)
ROADM
Macro Cells RRHs
Baseband Pool
ROADM
Small Metro Cells
This presentation contains Proprietary Information.
Not intended for public distribution
Page 32
5 - PON Performance Testing
Latency Measurements
Failover (Redundancy)
Measurement
Individual
Port
Measurements
This presentation contains Proprietary Information.
Not intended for public distribution
Traffic Test Pattern Selection
Page 33
Section 4
FUTURE DEVELOPMENT
This presentation contains Proprietary Information.
Not intended for public distribution
Page 34
Future: Real-Time CPRI or OBSAI Link
Monitoring
• Monitor RAN in real-time
– RF Signal Strength
– RRH/BBU Communication
Status
•
•
•
•
RRH
Remote monitoring
Real-time alarms and triggering
Reduce tower support costs
Reduce delay to problem
resolution
BBU
Central
Monitoring
Ethernet
Sales
Training
Q2 2011Information.
This presentation
contains
Proprietary
Not intendedVersion
for public
distribution
1.1
CPRI or
OBSAI
Link
Page 35
Future:
• 9.8 Gbps Speed
• Packet Jitter Injection
and Analysis
• Clock PPM monitoring
• RRH emulation for BBU
testing
• BBU emulation for RRH
testing
This presentation contains Proprietary Information.
Not intended for public distribution
Page 36
RRH
CPRI or
OBSAI
Link
RRH Testing
Section 5
DEMO
This presentation contains Proprietary Information.
Not intended for public distribution
Page 37
Section 6
Q&A
This presentation contains Proprietary Information.
Not intended for public distribution
Page 38
Section 7
BACKUP SLIDES
This presentation contains Proprietary Information.
Not intended for public distribution
Page 39
Investigator = Referee
RRH Team
BBU Team
Software Team
Hardware Team
RF Engineers
DSP Engineers
Investigator
This presentation contains Proprietary Information.
Not intended for public distribution
Page 40
The Business of PREVENTION and
RECOVERY
This presentation contains Proprietary Information.
Not intended for public distribution
Page 41
2G to 4G/LTE Evolution: Multi-Technology
LTE
2G
2G Antenna
3G
2G
RRH
RF
3G
RRH
CPRI or
OBSAI
link
Digital
RF
LTE
RRH
W-CDMA
BBU
2G
Technology
This presentation contains Proprietary Information.
Not intended for public distribution
BBU
3G Evolution
Page 42
Legacy
4G/LTE
4G/LTE Evolution: Baseband Pooling
RRH
Up to
10km
RRH
BBU
RRH
Up to
60km
2G/3G
RRH
Baseband Pool
RRH
RRH
Passive
Optical
Network
Next Generation
This presentation contains Proprietary Information.
Not intended for public distribution
Page 43
BBU
BBU
BBU
BBU
BBU
Heterogeneous Network (HetNet)
Evolution
To Backhaul
BBU
ROADM
BBU
BBU
BBU
Optical
Terminal
CPRI or OBSAI Across
WDM
(Distance to 50km)
ROADM
BBU
Macro Cells RRHs
Baseband Pool
ROADM
Small Metro Cells
This presentation contains Proprietary Information.
Not intended for public distribution
Page 44
LTE Radio Access Networks Testing
Challenges
• Limited RF signal availability
– Only digital RF at the bottom
of the tower
RRH
• RRH separation makes it
difficult to debug commands
• Distance requires more
performance testing of PON
• Multi-technology introduces
complex timing issues
This presentation contains Proprietary Information.
Not intended for public distribution
CPRI/OBSAI
link
DWDM
PON
BBU
Page 45
Customize Protocol Decodes
• Most companies
have CPRI or OBSAI
customizations
• Insert your own CPRI
decodes for display in
viewer
This presentation contains Proprietary Information.
Not intended for public distribution
Page 46
Impairment GUI
Fibre, coax,
twisted pair
cable types
Time or
Cable Length
Units in:
Bit Error
Rate
monitoring
Distance: feet,
meters (m,km)
Time: seconds
(uS, mS, S)
Transmitted
frame count
and link
status
This presentation contains Proprietary Information.
Not intended for public distribution
Page 47
Loss of Signal Debug Sequence
1. Check Bit Error Rate to rule out
physical layer issues.
2. Capture trace around error
conditions.
3. Check trace for CPRI compliance
4. Check trace for interoperability
issues on RRH/BBU control layer
5. Compare error condition traces
with normal operation traces to
find operational differences.
This presentation contains Proprietary Information.
Not intended for public distribution
Page 48
RRH/BBU C&M Layer Example
(TCP)
Time: 11 40.146655
Time: 10 40.040405
NPWR=300
MINOHPWR=230
MAXNUMCARR=8
MAXNUMPORTCARR=8
APCF=-15000
MASTERPORT=NO MASTERNUM=0
SLAVETCVR=RATE3
MASTERTCVR=NONE
LTECAP=0X0000003F HWTYPE="RRH" NUMTX=4
NUMRX=4 INFO=""
ADDLHW=NONE?EVENTENABLE:STATE=ENABLE?INTAL
MSTAT:INTALM=0X00200000,0X00000000
INTALM2=0X00000000,0X00000000
INTALM3=0X00000000,0X00000000?EXTALMSTAT:EXT
ALM=0X00000000?SIMULCAST:STATE=DISABLE?CPRID
ESC:NUMCPRIPORT=2 PORT1MODES=0X0000000
This presentation contains Proprietary Information.
Not intended for public distribution
Page 49
MESSAGE:TYPE=GETRESPONSE
TRANSACTION:ID=242
CPRISTAT:PORT1MODE=SLAVE
PORT2MODE=SLAVE
PORT1STATE=PASS
PORT2STATE=PASS
PORT1LNRATE=2
PORT2LNRATE=2
PORT1LNNEG=AUTO
PORT2LNNEG=AUTO
PORT1CMMODE=ACTIVE
PORT2CMMODE=ACTIVE
PORT1CMRATE=35
PORT2CMRATE=2
PORT1IQFMT=IQ16
RRH
Cross Trigger
BBU
Traditional
Network
Sales
Training
Q2 2011Information.
This presentation
contains
Proprietary
Not intendedVersion
for public
distribution
1.1
Page 50
Investigator