5530na hanoi training.ppt
TRANSCRIPT
Alcatel-Lucent University Antwerp
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University
5530 Network Analyzer
R4.1+
Alcatel-Lucent University Antwerp
University
Alcatel-Lucent University Antwerp
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University
Introduction
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5530 NA
5530 NA on-demand fault diagnosis tools. single-end line testing dynamic line management network analysis tools Northbound interface to upper-layer OSS applications. Multi-vendor plug-ins for third-party nodes
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System overview 5530 NA
Alcatel 73xx DSLAM3rd party DSLAM
5523 AWS 5530 NA
http https http
SNMP v1SNMP v3tftp
CPE xDSL modem
https introduced from R2.3clustering introduced from R3.3
5530 NA cluster
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5530NA – ASAM communication
SNMP TFTP
Network diagnosis
Protocol Handler
Network analysis
5530 NA
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Network Diagnosis
tools to quickly detect, resolve & troubleshoot DSL outages, actively and pro-actively.
Line State Diagnosis (R3.3+) Equipment fault diagnosis Real-time dashboard Line quality diagnosis: diagnosis and monitoring over time Short Line Quality Diagnosis (R3.3) Single End Line Testing: SELT Line Quality Validation (R4.1)
SELT can be used for loop qualification before a CPE is installed fault detection and localization when the CPE cannot be synchronized
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Network analysis
manage your installed DSL infrastructure pro-actively. Assess the impact of the introduction of new DSL
services and plan maintenance activities in your DSL network
Collect network-wide: line classification DSL operational behaviour information
Network-wide analysis functions: Network stability Network performance CPE classification
Detailed reports on network characteristics
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University
Getting started
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Connecting to the 5530 NA
Use your browser to connect to the 5530 NA http://<IP-address 5530NA>:8080 https://<IP-address 5530NA>:8443
5530 NA R2.3+ introduces secure http (https): Depending on your browser, one or more security
certificates may appear. Click on the Yes or Ok button to continue.
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Main (R3.3+)
NA menu options
Profile of logged in user
Access to help- user guide
About 5530 NA- product information- license information
Logout
Home- overview page (this page)
Current diagnosis inspections in database of 5530NA- number of inspections per type- inspection health- clickable per inspection type per health
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Inspect field
Port resource identifier TL1: <DSLAM-name>:<rackID>-<shelfID>-<slotID>-
<portID>Example: ISAM5:1-1-1-6
AWS: <DSLAM-name>:R<rackID>.S<shelfID>.LT<slotID>.<portID>
Example: ISAM5:R1.S1.LT1.6 User labels Customer ID Inspection ID
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Configure element manager(s)
Creation of a new element manager: Click on the “Add EML provider” button
Provide the IP address and account data for the AWS
Click on the “Add URL provider” buttonProvide name and URL for host fileFile://xxxxxxxxxxhtml://xxxxxxxxxxftp://yyyyyyyyyyyyy
Discover managed networks Click on the “Synchronise ASAMs” button
Display discovered ASAMs Click on the link behind the configured EML Reachability from the 5530 NA to ASAMs is shown
5530 NAconfiguration
Synchronization
• Add xxx provider• Delete• Edit (R2.3+)• Synchronise DSLAMs• Show synchronization report• Synchronization settings• Display ASAMs/provider
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Display discovered ASAMs
Click on the link behind the configured provider Reachability from the 5530 NA to ASAMs is also
shown
Reachable Unreachableor not supported
Synchronize button
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University
Network Diagnosis
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Network diagnosis Applications:
on-demand trouble shooting on a line (line monitoring)
identifies probable cause and provides repair advice equipment problem diagnosis (one-shot diagnosis)
similar to AWS Main characteristics:
monitoring of line parameters over time automatic analysis in real-time time saving can be executed by customer service representatives
no technical expertise required automated collection of:
max. attainable bit rate, attenuation, noise margin, bit loading, ...
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Network diagnosis
Diagnosis of one line starts with line state diagnosis: Line configuration overview Last detected CPE type SELT reference if available Line classification history Access to other line diagnosis tools
Dashboard, SELT, line quality diagnosis (LQD), short LQD, Line Quality Validation (LQV –> R4.1 only)
Line parameter summary If line is down equipment fault diagnosis is started Access to other NA tools related to that port
Diagnosis & SELT management, event history & NA configuration
Start “Line State Diagnosis”
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Line State Diagnosis report (R4.1)
New!
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Equipment fault diagnosis
If the line is DOWN, the 5530 NA diagnoses the problems.
The diagnosis verifies the existence and status of the following:
ASAM reset LT card & applique LT Port xDSL Line …
“detected equipment fault problems” window
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Dashboard inspection
real-time views of a DSL: display operational parameter values for the DSL detect line quality degradations.
updated every 10 s information appears in a separate window. Results cannot be saved. Window layout can be saved
data shown Bit rates, attenuations, noise margins, ATM traffic, coding
violations & Forward Error CorrectionsEach window can be expanded
Alarms & events Configuration details
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Dashboard inspection
Hide/unhide measure pointsMaximize windowHide window
Hide/unhide data window
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Line quality diagnosis Start a (short) line quality diagnosis
Click on ‘short diagnosis’ or ‘diagnosis’ Provide collection mode parameters
For LQD only (not short LQD) Click on ‘Continue inspection’ Parameters monitored:
Line status PM data, attainable & actual line rate ATM traffic Noise margins & attenuation Bit loading and bit swapping Coding violations & Forward Error
Corrections SNR, QLN, Hlog Output power …
Line state diagnosis
report
(Short) Diagnosis
inspection?
Provide monitoring& collection period
parameters
cancel
Monitoring
continue
5530NA Home
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Inspection principles
NE
...
tHistorical line data(data in MIB)
Line state report Monitoring phase(in background)
Monitoring configuration
Notification sent
1. Automatic export?2. Data purged
Purge timeout
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Diagnosis concept
LQD measurement symptoms 1 or more symptoms (combined or not) possible problem
Detected problem also based upon extensive Alcatel field experience
No 100% certainty confidence level given Confidence level: based upon the combination and clarity of
symptoms
Line Quality Diagnosismeasurement
Symptom x Detected problem Axx% confidence
Symptom y
Symptom z
Symptom …
Detected problem Byy% confidence
Detected problem Czz% confidence
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Block line quality diagnosis
Block line quality inspection Line quality diagnosis on multiple DSL lines in one go
Max. block inspection size: 200 to 500 DSL lines separated by a comma in the inspect field
Could also be started from network analysis classification reports
No line state report is given
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Block Inspection Execution
5530 NA schedules Line Quality Diagnosis on the individual lines
Execution time depends on Number of lines contained in inspection block Max. number of inspections per NE Block inspection quota
Inspection management Cancel, purge of the block inspection is propagated to all
contained diagnosis processes
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Single End Line Testing
SELT test on lines that are not in sync. SELT can detect open and short loops up to a certain
lengthSignal reflection measurement
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Managing inspections
Inspections appear in the current inspection list until purge timeout [hours] Dashboard inspections only appear in list when running.
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Managing inspections
View: look at report detailsDelete: report deleted from 5530 NAStop: stops running inspectionEdit: Edits description field
Health: good or bad/
Sort according to (blue items are clickable)
Filter criteria
Sort ascendingSort descending
Depending NA release this window might differ slightly
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5530NA homepage
When logging into the 5530NA the home page gives an overview of all inspections in the database
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G.SHDSL Support R2.3+
Network Diagnosis and Analysis support for G.SHDSL
Two- and four-wire mode Repeaters not supported
Network Diagnosis Package Equipment Fault Diagnosis Line Quality Diagnosis
Detection of line instabilities based on MTBE
Real-time dashboard Network Analysis Package
Network AnalysisLine classification
taking MTBE into account (line instabilities)
Network Detail Reports
Measurement of Bit rate (US and DS) Attenuation (US and DS) Noise Margin (US and DS) Coding Violations
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Network Diagnosis interpretation
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Network Diagnosis
Loop diagnostic mode = robust initialization that allows to perform DELT measurements even when line is not able to get into showtime mode
Available for ADSL2 and VDSL2
in-service monitoring (with optional carrier data mode)
synchronized
DELT: loop diagnostics mode
loop diagnostics (LD) initialization
SELT: reflectometry
synchronization/LD not possible
e.g. impulsenoise
e.g. cable cut
NEW IN R4.1NEW IN R4.1
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DELT parameters
Measurable parameters, but they are not necessarely shown in the 5530 NA reports
DELT: loop diagnostics mode
loop diagnostics (LD) initialization
e.g. impulsenoise
•ISM = In-Service Monitoring•CD = Carrier Data•CD+ = Carrier Data with reinit•LD = Loop Diagnostic
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Detected problems
Bridgedtap
MissingPOTS/ISDN
splitter
RFI
Crosstalk•Low-frequency•ISDN, HDSL, SHDSL, T1/E1 disturber
•Open circuit•Intermittentcontact
Shortcircuit
Degradedcontact
Impulsenoise
Untwistedin-housewiring
CPE interoperabilityproblem
Loopunbalance
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Definitions
Line stability Line is unstable: (on average) spontaneous resync within
6 hours! MTBR = Mean Time Between Resynchronisations
Line quality Poor quality: lots of code violations
CV = CRC error on ADSL superframe MTBE = Mean Time Between Error Events
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Definitions: MTBE
Case 1: Line 1: Line 2:
Which line has best quality? Case 2:
Line 1: Line 2:
Which line has best quality?
1Error… …
t
t100Errors
24 errors
400 errors
t
t
Rate: 500kbps
Rate: 5Mbps
MTBE = rate x total showtime/# of errored events
Error event
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Definitions: Service Stability
Service degradation because of transmission errors or spontaneous resynchronizations.
On the line state report
On the LQD report
From NA R3.1 these thresholds are configurable through the service templates
MTBE<1E+08bits, MTBE<60s or MTBR<6hMTBE= show-time / #CV events [sec]MTBE= show-time x rate/#CV events [bits]MTBR= show-time/spont. resyns [sec]
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xDSL performance
Does the DSL line match the expected performance for a specified attenuation?
undetermined - no data for attainable bit rate or attenuation Degraded:
attainable bit rate < bad attainable bit rate curve Medium:
bad attainable bit rate < attainable bit rate < good att. bit rate
Good: good attainable bit rate < attainable bit rate
Configure xDSL performance settings system settings Only shown in “classification history” in link state
diagnosis report
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xDSL performance
Graph specifies the classification for xDSL performance
Atta
inab
le b
it ra
te
Attenuation
Attainable (good)Attainable (bad)
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Monitoring configuration (R4.1)
Automatic duration is 6 or 18 hours of show-show-timetime. Decision based upon comparison of historical service stability with the current!
NORMAL_INIT: Enable line reinitialization: allows collection of QLN, Hlog
ROBUST_INIT: Enable Loop Diagnostics (LD) mode
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Line quality diagnosis report
5530 NANetwork
diagnosis
diagnosis management
• Inspection ID
Notification mail link
Show details
• Show details
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LQD report windows
Service stability Based on configured threshold values of MTBE & MTBR in service
template CPE type
Displays the friendly name for the CPE type as defined in the CPE filter.
Profile details of xDSL service & xDSL spectrum profile
Communicated through EOC
R4.1: name of used service template is shown
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LQD report windows
Service stability & xDSL performance daily line classification (network analysis)
Network analysis reports only average line classifications
on a weekly or monthly basis
Daily line classification(network analysis)Previous & current LQDs
Inspection ID
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Report export
Report can be exported to 2 different file types CSV export
Data for use in a spreadsheet Data put in simple ASCII file separated with commas
Min. interval is 3 minutes (even if polling period is smaller) RAW export
Proprietary 5530 NA file (R2.3)<name>_id_#_.raw.gz
XML file (R3.1+)<name>_id_#_.xml.gz
Full data detail for archiving and re-importing in another serverImport via Network diagnosis > Diagnosis management
Files are saved on operator’s machine (not the 5530 NA server)
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LQD report windows
Confidence based on severity and symptoms detected A complete description of all problems is provided in
the user guide of the 5530NA.
Detected RFIs
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LQD report windows
Show details of LQD report Details include monitoring information, parameter
summary, event summary and a collection of diagrams representing all collected data
Specific LQD report detail terminology: Spontaneous resync: re-init within 40s Profile switch: change in xDSL profiles, the detected line
quality problems are based on the symptoms since the last profile change
Coding Violations: CRC error in ADSL superframe Forward Error Corrections: corrections made by Reed
Solomon Quiet Line Noise: representation of actual noise on line Transfer function magnitude (Hlog):
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Inspection info & event summary
MTBE is for up and down together MTBR is average for total showtime
= showtime period / # of spontaneous resyncs
Bitswaps > actual bitswapping eventsNOT the number of bits swapped! (found in event details)
Clicking on the event will provide you the details
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Event summary
Bitswaps Date & time of bitswap event Number of bits swap
Spontaneous resync Date & time of resync event Total duration of the resynchronisation
Profile switch Number of port configuration
changes Collection failure Robust Resyncs
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Collected data graphs: guidelines
All collected data is put into several graphs where for the majority these rules apply
Line downCollection failureCollector down
Measurement data 1Measurement data 2Measurement data 3
Mea
sure
d da
ta s
cale Loop
Diagnostics
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Bitloading contour
Bitloading in time
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Bitloading
Variance [bits] Represents the variation in bits of that carrier for the total
showtime
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SNR
Variance represents the average variation of the SNR over the
spectrum
Robust init results
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Bitrate graphs
Rates shown: Actual bitrate Attainable bitrate ATM traffic
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Coding violations graph
CV = CRC error in ADSL superframe These errors are after correction by Reed Solomon
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Forward Error Correction graph
FEC: number of bytes corrected by Reed Solomon during polling interval.
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Noise margin graphs
Noise margin depends on configuration in the ADSL line profile Modem could lower or increase output power
Noise margins show Configured noise margins & actual noise margin
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Attenuation graph
Attenuation on a customer line should remain stable
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Output power graph
Output power can depend on noise margin configuration
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Line Quality Validation (LQV)
LQV : inspection to validate the operational behaviour of a line
Very lightweight Polling once every 4 hours (configurable in service template) Stops after 6 hours of show time –OR- after 7 weeks of
monitoring Only data needed to determine the operational behaviour is
collected (calculation of MTBE & MTBR) The (only) result is the stability of the line :
OKNOKUnknown
Notification sent by e-mail
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Line Quality Validation: duration
Validation monitoring duration = minimum amount of showtime required to decide that line is stable/risky = 6 hours by default (configurable)
Decision that line is unstable can already be taken at earliest when first sample is taken (after 4 hours) (when MTBE/MTBR cannot fall below threshold for unstable line anymore even if remainder of required showtime would be error free)
Maximum duration: 7 days
InitiationLQV validation
polling period
validation monitoring duration
data collection point + decision stable/riskydata collection point + decision unstable
Show
time
dura
tion
line upline down
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CPE filters
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CPE filters
In the EOC some parameters are communicated about the CPE
System vendor & System Vendor model Modem vendor & modem vendor model Serial number
Based on these parameters we can assign a CPE to a certain category and give it a friendly name
Friendly name shown in diagnostic reports Category used in Analysis reports Certain CPE types can be blacklisted
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Blacklisted / not interoperable
Configuration > CPE filter > Definition Blacklisted
User is advised to use a CPE that is not on the black list. A line quality diagnosis cannot be performed for the
blacklisted CPE Not interoperable
If blacklist is configured by setting the “Not interoperable” flag True, a LQD inspection can be started even when the CPE is blacklisted!
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CPE filter definition (Black/White List)
Create new CPE category / friendly name Shows all discovered blacklisted CPE categories in table
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CPE Filter Editor
Define details per CPE category System IDs & models Modem IDs & models Serial number Blacklist details: blacklisted and/or not interopable
Define filter order Once a match is found for a CPE it is not matched to the next
entries
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CPE filter in action
In the line state diagnosis report and the line quality diagnosis report the CPE type is indicated by the friendly name
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Service providers & ports
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Used for wholesale Each port assigned to a service provider A user belonging to a service provider can only operate
on those ports
Service provider
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Configuring the Service provider
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Assigning a user to a Service provider
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Port management
Specifies user friendly label for the port Specifies service template to be used for operations on
the port Assigns the port to a service provider Specifies the current DLM state of the port Available via
Line State diagnostics report Main menu: Configuration > ports management
5530 NA Configuration
Ports management
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Configuring ports
Methods to configure a port Configure one-by-one manually
Import from XML file triggered by userSpecify the list of ports in an XML file & import
through GUI
Import from XML automaticSpecify the list of ports in an XML file & place the file
in port import path (system settings), which is “/var/tmp/8080” by default
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Configuring ports manually 1/2
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Configuring ports manually 2/2
The line state diagnosis report allows to add/modify the port configuration Labels Service template & Service provider DLM state
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Configuring ports via XML
Configuration Port management Bulk operations tab
Enter filename of XML file<!ELEMENT DlmMapping (Mapping+)>
<!ATTLIST DlmMapping version CDATA #REQUIRED >
<!ELEMENT Mapping (#PCDATA)>
<!ATTLIST Mapping port CDATA #REQUIRED label CDATA #IMPLIED serviceTemplate CDATA #IMPLIED serviceProvider CDATA #IMPLIED dlmState CDATA #IMPLIED >
<!-- Sample XML-->
<DlmMapping version="version 1.0">
<Mapping port="frodo:1-1-2-1“ label="f21“ serviceProvider="ServiceProvider1“ serviceTemplate="ServiceTemplate1“ />
<Mapping port="frodo:1-1-3-1“ label="f31“ />
</DlmMapping>
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Bulk import of ports via XML
XML file on server side
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Network analysis
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Network analysis overview
Build-up operational database of DSL Statistical collection of key operational DSL
parameters across entire installed base
Classification of installed based: red, yellow, green clusters (analysis report)
Assists with introduction and deployment of advanced DSL services
Line classification basis for upgrade decisions
Helps to identify poor lines and network problems (e.g. strong crosstalk)
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Data collection principle
Inventory of all configured DSL lines X datapoints for each line,
The more datapoints the more confident the end result. only one sample a day. datapoint = data/counter collection of historical line parameters
line rates, noise margins, attenuation, CV interleaving, CPE info, cust. ID …
Data collection is responsibility of data collector. Data collected at a random time
At the end of each day the reports are generated
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Data storage
5530 NA can store several sets of network assessments. This helps to determine the variation over a period of
time. Only one assessment can be active at a given time!
The three types of network assessments are: Planned Current Previous
From R2.3 up to X assessments can be stored on the 5530NA
X is configurable via system settings (default = 12)
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Network assessment principle
Snapshotn-x
Snapshotn
tNetwork Assessment
DataCollection
(continuous)
DataStorage
Reports
Aggregation period:1 week or 1 month
The NA polls the entire network every day For enabled nodes
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Analysis process
Assessmentprocess
Operational xDSL Parameters+
classification data
Network Collector
NA Export
Network Analysis Network Details
Operator
Assessment Management
Administrator
Network analysis Network details
Analysisprocess
REPORTING
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Assessments management: overview table
AssessmentAssessment Assessment
PLANNED CURRENT PREVIOUS
AssessmentProcess
Network Collector
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Assessments management: assessment shift
PurgedAssessment Assessment
PLANNED CURRENT PREVIOUS
Assessment
Created
Shift happens when CURRENT is COMPLETED and PLANNED start date is reached
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Data collector
On which DSLAM do we enable data collection? Start data collection Stop data collection Collection statistics Failure log
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Plan network analysis
Plan a new network analysis & provide:
Aggregation periodOver which period do we
generate reports1 wk or 1 month
Start timeImmediate or after current
period
Only one assessment can run at a time
5530 NAMain menu:
Analysis
Report definition
• Apply changes• Reset values•Delete
Periods
Provide parameters
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Report Filters
Use filters to determine the criteria on which reports are created, including the detail reports.
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Filter Definition
Different criterias are available and can be combined
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DSLAM selectors
Seperate ASAMs by a comma Check if ASAMs are known by 5530NA
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Reporting
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Network analysis conclusion
Statistical collection of key xdsl parameters of all lines
Necessary tool to plan maintenance activities
Invaluable tool when planning the introduction of new services
Analysis capabilities based on Alcatel’s experience
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Network detail report capabilities
Provides a detailed report on the behaviour of your network Attainable bitrate vs attenuation contour plot graphs Attenuation upstream vs attenuation downstream contour plot
graph Attainable bitrate histograms Attenuation histograms Attainable bitrate vs attenuation line graphs Noise margin histograms Output power histograms
Visualises all retrieved data of the selected network assessment
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5530NA Homepage & network stability analysis
When logging into the 5530NA the home page shows the current stability analysis pie chart
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Trigger configuration
Used to trigger commands if changes are found in the analysis data for certain parameters.
The collected data is compared with data collected the previous day.
Triggers allow the 5530 NA to be proactive in maintaining the network to offer improved data reliability and automated network
diagnosis. Following changes are monitored to trigger specific actions:
CPE type customer ID stability profile service template
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Trigger configuration
ActionsChanges Configure actions
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Triggers in action
Here the stability degradation triggers an automatic LQD To view all automatically triggered quality diagnostics filter
on user name: Analysis triggerAnalysis trigger
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Network analysis interpretation
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Analysis report: breakdown
line export
xDSL line TL1 addressesStored on server (/var/tmp)
Start a block line quality diagnostics
5530 NA Analysis
Reporting
Analysis reports:Stability analysisPrequalification compliancePerformance analysis
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Confidence histogram
Confidence is based upon the number of datapoints collected all datapoints collected = 100% confidence Less datapoints give a lower confidence
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Showtime distribution graph
Only for stability analysis report
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Report header
Only for Analysis reports
Filter used to generate reports
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Stability & Performance Analysis Report
Stability Analysis Classified according to line stability Line stability is defined in service template 3 categories
Stable, Risky & Unstable Performance Analysis
Classified according to line performanceAttainable bitrate vs Attenuation
Performance graphs configurable via system settings 3 categories
Good, Medium & Bad
Category 1Category 2
Category 3
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Prequalification compliance report
The prequalification compliance report classifies the lines according to their prequalification health.
default prequalification health rule (defined in the service template):
Actual LR < Planned LR => NOK
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CPE categories report
CPE category analysis report each bar represents the number of CPEs in a CPE category
CPE categories configurable via Configuration > CPE filter
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Active ports analysis report
You can use the Active ports analysis report to generate a Prequalification health reportPrequalification health report and a Detailed bit rates Detailed bit rates reportreport for a DSLAM selector.
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Detail reports
ADSL, ADSL2, RE-ADSL, ADSL2+, SHDSL, and VDSL report details, which are displayed in graphs, show the relationship and distribution of operational parameters.
You can only view network assessment report details on the second day of collection.
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attainable bitrate vs attenuation contour plot
The color indicates how many lines have an attainable bitrate and attenuation in that range
Majority of lines here have a high attainable bitrate with a low attenuation
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Attenuation contour plot
Attenuation of a line is in relation to the length of the line There should be a linear relationship between the attenuation
downstream and the attenuation upstream (see graph)
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Attainable bitrate histogram
Red bar indicates number of lines that have that attainable bitrate
Blue line is the accumulation of all lines in percentage Apc. 5% of lines can not reach 3Mbps
downstream upstream
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Attenuation histogram
Red bar indicates how many lines are within that attenuation interval
Blue line is the accumulation of all lines in percentage
downstream upstream
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Output Power histogram (R2.3)
Red bar indicates how many lines are within that output power interval
Blue line is the accumulation of all lines in percentage
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Attainable bitrate vs attenuation line graph
For a certain attenuation range how many lines can reach that bitrate
Attenuation is an indication for the length of a loop
downstream upstream
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Noise margin histogram
Red bar indicates how many lines are within that noise margin interval
Blue line is the accumulation of all lines in percentage
downstream upstream
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Exporting: /opt/ni/bin/na_export.sh
Exporting of assessment and operational data Login on NA server as ni user
/opt/ni/bin/na_export.sh <path & filename>
Script will request which data to export
<filename>: filename of the dumpfile
This creates a clear text file (CSV) with your assessment data
Could be re-imported in xls or other applications
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Data interpretation
Correct interpretation of the data can only be done by understanding the xDSL line profile parameters in your network.
Typically noise margin parameters have a large impact on your 5530 NA result
Lower max. noise margin modem might lower its output power
Lower output power reduced attainable bitrate (this makes it more difficult to assess your network for an upgrade)
But because the modem can increase its output power in case of increasing noise or higher requested bitrate making exactly the upgrade possible
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Sample report: bad connectors
suspected capacitive coupling due to bad connectors: typically RJ11 connector oxidationsuspected capacitive coupling due to bad connectors: typically RJ11 connector oxidation impedance is inversely proportional with the frequency so upstream will suffer more
upst
ream
atte
nuat
ion
[dB]
downstream attenuation [dB]
> upstream attenuation is higher than upstream attenuation is higher than expectedexpected
• for (small) percentage of lines
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Sample report: ISDN crosstalk
upst
ream
max
atta
inab
le b
itrat
e [k
b/s]
upstream attenuation [dB]> suspected ISDN crosstalk into US band of ADSL over POTSsuspected ISDN crosstalk into US band of ADSL over POTS
> upstream attainable bitrate is lower than upstream attainable bitrate is lower than expectedexpected
• for (small) percentage of lines
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www.alcatel-lucent.com
Alcatel-Lucent University Antwerp
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University
DSL technology refresh
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Quadrature Amplitude Modulation (QAM)
Transmitted data = Constellation
2
3
1
0
-1
-2
-3
0,5 1 1,5 2 2,5 3
1111 1001
0000
00110111 0101 0001
0110
1110
1101 1011
1100 1000 1010
0100 0010
1001 0000 1111
Symbol length (Ts)
Symbol is represented by a variation of amplitude & phase for a particular frequencyy = A . sin (2 f.t + )
4 bits/symbol>> QAM-16
t
A
A
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QAM and Noise
Constellation
1111 1001
0000
00110111 0101 0001
0110
1110
1101 1011
1100 1000 1010
0100 0010
0
2
3
1
-1
-2
-3
0,5 1
1001
Parasite noiseSame frequency
Amplitude Phase
The Shannon-Hartley theorem : Capacity bps= 1/3 x W x SNR x G
0
2
3
1
-1
-2
-30,5 1
1011
Transmit Receive
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Bits/symbol QAM Signal/Noise ratio (dB) for BER<10-7
4 QAM-16 21,8
6 QAM-64 27,8
8 QAM-256 33,8
9 QAM-512 36,8
10 QAM-1.024 39,9
12 QAM-4.096 45,9
14 QAM-16.384 51,9
SNR/QAM relationship
Relation between the SNR and the max. QAM. (QAM is directly linked to the line rate)
To obtain a certain speed we need a min. SNR!
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Discrete Multi Tone (DMT)
For DSL, multiple carrier frequencies are modulated on the 1 ADSL line using QAM.
These frequencies are equally spaced and for each carrier the SNR is measured to determine the maximum achievable QAM.
The sum of all frequencies is put on the line
This concept is called Discrete Multi Tone (DMT)
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Discrete Multi Tone example
Ts (Symbol Time)
QAM-4 f1
QAM-16 f2
QAM-4 f3
= DMT
1 DMT Symbol
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#bits per carrier
Bits/carrier
Carriers
23456789
1011121314
Maximum value after SNR measurement per carrier at startup
Possible working value at startup
1
126
Bit swapping
After start-up we‘ll use a lower QAM than possible on most of the carriers
measured SNR at startup determines maximum possible QAM at start-up
E.g.: max. QAM-4096 (12 bits per symbol) used QAM on that carrier : QAM-1024 (10 bits per symbol) 2 extra bits that could be allocated
During show-time, SNR is measured regularly (default every sec)
if SNR degrades lower QAM bits of that carrier will be reallocated to other carriers (where max. QAM > actual used QAM)
modems spread out the reallocated bits over numerous carriers.
127
Bit-swapping explained
Bits/carrier
Carriers
23456789
1011121314
1
Sudden frequency interference decreases SNR on a number of carriers
Current max. bits/carrier
Current used bits/carrier
128
Bit-swapping explained (2)
Bits/carrier
Carriers
23456789
1011121314
1
A lower SNR also lowers our max QAM (the number of bits on those carriers)
Current max. bits/carrier
Current used bits/carrier
Affected frequencies
129
Bit-swapping explained (3)
Bits/carrier
Carriers
23456789
1011121314
1
Current max. bits/carrier
Current used bits/carrier
130
Bit-swapping explained (4)
Bits/carrier
Carriers
23456789
1011121314
1
Current max. bits/carrier
Current used bits/carrier
Noise margin is spread over the full spectrum
Bitswapping protects your DSL line against slowly changing line conditions
131
Reed-Solomon correction mode
Byte1234
239
k byte message vector
n byte code vector
254255
240
n - k check bytes
Code RS(255,239)
Distance : n-k+1d= 255-239+1
d=17
Correction: (d-1)/2c=(17-1)/2
c = 8
With 16 check bytes, the RS code can correct up to 8 erroneous bytes
per code vector
Error correction overhead = 16/255 = 6.3 %
132
Reed Solomon
Message vector Ctrl
Received data
Transmitted data
Distance = 15-11+1= 5 Correction = (5-1)/2= 2
More than 2 lost bytes
Burst of errors
Data to be transmitted
Lost data
133
Interleaving
Message vector Ctrl Data to be transmitted
Transmitted Data
Bloc 0 Bloc 1 Bloc 2
Received Data
CtrlCorrection CtrlCorrection CtrlCorrection CtrlCorrection CtrlCorrection
Bloc 3 Bloc 4
Bloc 0 Bloc 1 Bloc 2 Bloc 3
Burst errors
6 lost bytes
1 Byte errorper bloc!
134
ADSL superframe
DS 3DS 2DS 1 DS 4 DS 68DS 67. . . . . SS 69
SUPERFRAME17 ms
DMT Symbol
DMT symbol a DMT symbol is the sum of all symbols on each individual
carrier Data Symbol (DS)
a data symbol is used to transmit payload information Synchronization Symbol (SS)
a synchronization symbol is transmitted after 68 data symbols to assure synchronization and to detect possible loss of frame
ADSL symbol period Ts=17ms/69 = 246,377 s Ts=17ms/68 = 250 s (symbol period for the data plane)
135
Trellis coding
Trellis coding is another error detection and correction mechanism which is optional for ADSL.
Trellis principle looking at the complete data, you’re able to detect and
correct errors, similar to detection and correction is spoken language.
Example :transmitted data the water is wet and coldreceived data the water is llet and cold
by looking at the word “let” only, we can not decide that the sentence is wrong.
by looking at the information before and after the word (context), we can safely say that it should be “wet” instead of “let”.
136
ADSL & Reed Solomon
DS 3DS 2DS 1 DS 4 DS 68DS 67. . . . . SS 69
SUPERFRAME17 ms
DMT Symbol
Assume Trellis coding is NOT used ! 1 data symbol corresponds to a 255 RS word. Some bytes in the
RS word are framing overhead used for modem to modem communication (EOC, AOC, IB, CRC)
If RS is not used, our data still runs through the RS decoder. Maximum downstream ADSL speed for our data :
with RS (255-16-1)*8bits/byte*4000 symb/sec = 7,616 Mbps
without RS (255-1)*8bits/byte*4000 symb/sec = 8,128 Mbps Currently, more than 1 RS word can be mapped to 1 DMT
symbol. Rates higher than 8,1 Mbps are possible
137
Coding gain
Bits/symbol QAM uncoded Trellis RS Trellis + RS4 QAM-16 21,5 16 17,5 12,56 QAM-64 27,5 22 23,5 18,5
SNR for BER = 1E-7
From the table QAM vs. SNR, we have seen that to attain a BER of 10-7 for a specific QAM you need a certain SNR.
if the SNR is lower than this value, the BER will be too high. by introducing error detection and correction you lower the BER
because a number of the introduced errors will be corrected. The mechanism introduces a coding gain resulting in an
actual lower SNR that is needed to achieve a certain constellation.
Trellis introduces a brute coding gain of approximately 5,5dB RS introduces a brute coding gain of approximately 4dB Trellis & RS together introduce a brute gain of approximately
9dB
138
Data rate terminology
Net Data Rate (NDR) Rate at input of the PMS-TC layer (alfa/beta interface) sometimes referred to as the payload rate
OverHead data rate (OH) Sum of OAM data (e.g. EOC) and CRC bytes
Aggregate Data Rate (ADR) net data rate + overhead data rate Rate at input of RS encoder (A-interface)
Total Data Rate (TDR) aggregate data rate + RS coding overhead Rate at output of RS encoder = Rate at input of Trellis encoder
(delta-itf.) Line Rate (LR)
Total data rate + Trellis coding overhead Rate at output of Trellis encoder (U-interface) LR = ( sum of b(i) ) * symbol rate
139
Data rate terminology
Graphical Representation
bearer data + OAM + CRC
+ FEC overhead + Trellis bits
PMDPMS-TCPMS-TC
net data rate
(alpha-beta interface)
aggregate data rate
(A-interface)
total data rate (delta-interface)
line rate (U-interface)
NDR ADR
TDR Line rate
FEC overhead
application specificdata
TPS-TC
140
Impulse Noise Protection (INP) in ADSL2(+)
Impulse noise protection How much of the DMT symbol is protected? Protection via Reed Solomon and extended via interleaving
Which parameters influence the INP S = # DMT symbols per RS word D = interleaving depth (# of combined RS words used) N = Number of bytes per RS word (1 255 bytes) R = Number of RS overhead bytes (0 16 bytes)
(ms)delay 4
DS
NRDS0,5INP
141
Step 1: protection for 1RS / 1DMT symbol
NO interleaving introduced R=overhead bytes N=Total bytes K= payload bytes Correction on payload = R/2
What part of the DMT symbol is protected? Number of correctable bytes over number of bytes in DMT
symbol INP = DMT protection = payload correction / N = R / (2xN)
K R
DMT symbol
142
Assume 1 RS word / 4 DMT symbols & NO interleaving S = # DMT symbols per RS word = 4 We have seen before that RS correction = R/2
How much of the DMT symbol is protected? RS word is now spread over 4 DMT symbols
With R=16 you have 8 correctable bytes over 4 DMT symbols
INP = (# correctable bytes) / (#bytes in a DMT symbol)= = (R/2) / (N/S) = (S x R) /( 2 x N)
INP increases with a factor S
Step 2: protection for 1RS / S DMT symbols
DMT DMT
RS
DMT DMT
143
...
1 2 3 4 5 6
Step 3: introducing interleaving
Correction has improved by a factor D Errorred bytes are spread over “D” RS words Payload correction = D x R/2
DMT protection has as such also increased = # correctable bytes / N = (DxR)/(2xN)
BufferD
D = interleaving depthN = number of bytes per RS word
incoming
outgoing
Max. 255 Bytes
..
N
B1B1B1B1B2B2B2B2 BxBxBxBx Bz Bz BN BN BN BN...
Assume 1 interleaved RS word / DMT symbol
Size N
Max. 64
144
Step 4: all together
RS introduces a correction = R/2 RS correction presented by parameter R
Interleaving introduces an improvement on the number of correctable bytes
Interleaving represented by parameter D
S factor introduces an impact on the number of correctable bytes per DMT symbol
INP = (S x # correctable bytes) / N = S x R x D / (2 x N)
145
conclusions
INP = S x D x R / 2 x N How to increase the INP
Increase S > increases the introduced delay Increase D > increases the introduced delay Increase R > Decreases the available bitrate Decrease N > Decreases the available bitrate
When configuring a DSL port a max delay needs to be given and a minimum INP
This will impact the max. possible bitrate
Available Net data rate ≈ 32 kbps x (N-R) / S
146
Impact of INP/delay on performance When
Higher Minimum INP is required Lower Maximum delay is required
Rate will decrease Decrease of Efficiency on all datarates
Due to more coding overhead Decrease of Max Possible Net Datarates
decrease of “ceiling” on rate-reach curveDue to framing / coding Limitations
– TX limitations due to standard – RX limitations due to standard and chipset
But Performance might increase ! Performance is more than raw datarate only ! Due to lower BER, throughput might increase
Remark: increase only when impulse noise is really present
ceiling
efficiency
NetDatarate
Reach
ceiling
efficiency
NetDatarate
Total Datarate
147
Impact of INP/delay on performance
Decrease of Efficiency (on all rates) Terminology
Efficiency = Net Datarate / Total Datarate– Net Datarate = without RSOH– Total Datarate = with RSOH– RSOH = Reed Solomon Overhead
Efficiency = 1 – Percentage RSOH
Approximate FormulaPercentage RSOH = max ( 6.25, INP/(2*Delay) ) %
– Note : Delay in [ms], INP in symbol.Percentage Rate_loss = Percentage RSOH – 6.25
– 6.25 % = RSOH already needed for “normal” coding gainZero Loss when : Delay >= 8 * INP
148
Figure 1 :
Net
Dat
arat
e (b
ps)
Total Data Rate (bits/symbol) x 4000 symbols/sec = bps
D=384D=511D=384D=511
D=384D=511
D=384D=511
ADSL2+ADSL2+
149
Figure 2 :
x 4000 symbols/sec = bps
D=384D=511D=384D=511
D=384D=511
D=511D=384
D=511
D=384
ADSL2+ADSL2+
Total Data Rate (bits/symbol)
Net
Dat
arat
e (b
ps)
150
Figure 3 :
x 4000 symbols/sec = bps
ADSL2+ADSL2+
Total Data Rate (bits/symbol)
Net
Dat
arat
e (b
ps)
151
Rate adaptation mode: operator controlled
The modems will synchronize to a line rate which is capable to support the operator set “planned bitrate” if the attainable line rate is planned bitrate
If the modems are not able to achieve the planned bit rate they will not synchronize and an alarm is generated
kbits/s
Planned bitrate = 500 kbits/s
512kbits/sActual rate
152
Rate adaptation mode: automatic (ADSL2 with SRA)
modems synchronize between a set minimum and maximum online adaptation to degrading or improving line conditions If the modems can’t synchronize, an alarm is generated.
kbits/s
MaxLR
MLR
ALR
t
Reset
threshold bit rate
153
Some examples of ‘new’ annexes: Annex I, J and M
UPAnnex A
UP
1.1 MHz
POTS
Annex B
Annex I
Annex J
Annex M
ISD
NPO
TSDOWN
138kHz
UP
UP
UP
UP
DOWN
DOWN
DOWN
DOWN
120kHz 276kHz
All digital
154
ADSL2+ doubles the frequency spectrum
155
Reach Extended ADSL2 concept
Same or even less total Tx power On long loops (e.g. up to 5.5 km 26 AWG) Increase in reach of 300-600m (26 AWG, 0.4mm loop) New ADSL2 PSD mask with reduced crosstalk to other
DSL services. Leads to a small reach increase on the longest loop of
about 0,5 kft relative to ADSL2, if SHDSL is a dominating crosstalker.
In self-crosstalk the length increases up to 600m.
using a higher power level (PSD) in a smaller band
156
READSL2: PSD masks
2 modes defined Non overlapped Overlapped: optional (not implemented)
2 Upstream PSD masks Higher PSD level in narrower frequency band. Same total power
1 Downstream PSD mask Boosted PSD level over half the bandwidth. Same total power
PSD(dBm/Hz)
6 14 24 32 128 255
-32,9-36,4-38,0
-37,0
carrier
-40,0
mode 1mode 2
157
VDSL2 Band plans - ETSI
Band plans 998 and 997 + Variants Accommodate POTS & ISDN overlay Different US0 types
A: “normal US0” (25-138 kHz) M: “extended US0” (25-276 kHz) B: “shifted US0” (120-276 kHz)“No US0" (f0 = N/A)
f0L f0H f1 f2 f3 f4 f5=12
TBD f [MHz]
US0 DS1 US1 DS2 US2
Band plan
Band-edge frequencies (As defined in the generic band plan
Figure 7-1) f0L f0H f1 f2 f3 f4 f5 kHz kHz kHz kHz kHz kHz kHz
25 138 138 997 25
276
276
3000 5100 7050 12000
25 138 138
25 276 276
120 276 276 998
N/A N/A 138
3750 5200 8500 12000
158
VDSL spectrum - ETSI
ISDNPOTS f
DMT
138 kHz 1.1MHz 12MHzoptional upstream band downstream band upstream band
~25 kHz
Plan 997– optimized for optimized for symmetrysymmetrydown up updown
0.138..0.276 3.0 5.1 7.05 12.0 MHz
down up updown
3.75 5.2 8.5 12.0 MHz
ADSL
0.138 1.1 MHz
Plan 998 - optimized for asymmetryasymmetry
f1f0 f2 f3 f4 f5
0.138..0.276
159
VDSL2 amendment, bandplan for region B, ETSI (jan.07)
f0L f0HkHz kHz
A 25 138M 25 276A 25 138
997E30
A 25 138M 25 276B 120 276
A 25 138B 120 276
HPE17HPE30 30000
US4
US3
US4176647050 10125 12000 14000 21450 24890
US0 DS1 US1 DS2 US2 DS3 DS4998ADE30 30000
176645200
US3
DS2
DS3
8500 12000
138
3750
276
997
998E30
998E17
997E17
998
24890
DS4US2
24890DS3US2
US3
US0 DS1 US1
998ADE17 276276138
bandplan
DS1 US1 DS2
f2kHz
f1kHz
US0 type
30000
US4DS3 US3 DS4
19500 2700017664
f9kHz
14000
f3 f4 f5 f6 f7 f8kHz
276
kHz
12000
US1 DS2DS1
138
kHz
138
kHz kHz kHzUS2
5200 8500
3000 5100 7050
138
276138
US0138
138138
US0
30000
12000
276
1400017664
21450276
138276
3750
160
Noise margin parameters
SNR (dB)
SNR needed for the configured line rateS0
NM (dB)
t (s)
SNR measured at startup (Pmax)
6dBTARGET NOISE MARGIN(TNM)
MAX. ADD. NOISE MARGIN(MANM)
S2 = SNR needed for startup
= S0 + TNM
S2
S1
S1 = SNR for max. output power at startup
S3 = SNR AT startup = S2 + MANM
S3
MINIMUM NOISE MARGIN(MinNM)
Adjust output power
!>1’: RESET
STARTUP SHOWTIME
MAX. NOISE MARGIN(MaxNM)