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Brendan kearns berlin 2012 vn3

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Presentation to NGN Signalling Forum 2012

Presentation to NGN Signalling Forum 2012

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  • 1. IMS Signalling Design and Customer Experience 13 th NGN Signalling Forum Berlin 31st January 2012 Brendan Kearns eircom Shane Dempsey TSSG
  • 2. Contents
    • (Eircom are largest fixed line op in Ireland)
    • eircom RCS trial
    • IMS deployment
    • Example deployment issue
      • Methods to minimise post dial delay
    • Example deployment issue
      • Methods to ensure call quality
    • Conclusion
  • 3. Eircom Rich Communication Suite 2.0 Trial Subscriber Databases Application Servers Provisioning Billing Alarms Circuit Switched Mobile IMS Core Transit Layer & PSTN Residential & Enterprise Users Web HLR IMS MSC MGC MG VoIP IM ENUM HSS LEG MOB Client WEB PH MOD ISDN Face Book Client VCC HLR PRES PC Client Client Client Client
  • 4. Eircom RCS: Some Findings Subscriber Databases Application Servers Provisioning Billing Alarms Circuit Switched Mobile IMS Core Transit Layer & PSTN Customers Web HLR IMS MSC MGC MG VoIP IM ENUM HSS LEG MOB Client WEB PH MOD ISDN Face Book Client VCC HLR PRES PC Client Client Client Client Residential Users Liked Media Share Enterprise Users Liked Single No. & Presence User Experience Dominated By The Simple: Handset & Client Interface, callQ, PDD Web Client Made Service Platform Independant
  • 5. IMS Deployment Timelines
    • IMS deployed in November 2011
      • High Level Design, LLD, acceptance test (300) phases
      • First line voice commercial trial
      • Onboard provisioning & PSTN billing
    • Wider deployment during 2012
      • Geographical redundancy
      • SIP Trunking & NGIN integration
      • Provisioning & billing integration
      • Consolation of Subscriber Data begins (HSS/hlr)
    • (SIP interconnect for HD voice & RCS)
  • 6. Initial Deployment & First Line Voice Subscriber Databases Application Servers Provisioning Billing Alarms Circuit Switched Mobile IMS Core Transit Layer & PSTN Customers Web HLR IMS MGC MG RES ENUM HSS PSTN MOB Client Residential Gateway PH MODEM ISDN MGW MGC
  • 7. Full Deployment & SIP Trunking Subscriber Databases Application Servers Provisioning Billing Alarms Circuit Switched Mobile IMS Core Transit Layer & PSTN Customers Web HLR IMS MSC MGC MG PRV SA RES NGIN ENUM HSS LEG MOB Client RGW PH MOD ISDN MGC SELF CARE IMS SIPT IPBX TOOLS IM SIP Interconnect
  • 8. Sample Deployment Issue Post Dial Delay
  • 9. Post Dial Delay: Analogue Phone on Home Gateway
    • En-bloc sending from handset
      • User knows number length thus no issue
    • Irish number plan is variable length
      • Overlap on PSTN
      • Now En-Bloc on IMS after time out (AGCF would have same issue)
    • Solutions
      • Append #
      • Digit map in gateway
      • “ Network” & “User” overlap sending with feedback from network
  • 10. Overlap Sending is one possible solution Phone Residential Gateway IMS MGCF TERM Exchange En-Bloc Sending Phase User Overlap Phase Network Overlap Phase Address Incomplete Minimum Digits Matched In CPE OFF HOOK INVITE Incomplete Digit Match In IMS Incomplete Address 484 Minimum Digits Req = N Send Digits in Invites INVITE Digit Match Found In IMS. Normal Call Processing IAM More Digits IMS Cannot Determine Number Ln 183 (No SDP) Send Digits In Info INFO No Digit Analysis In IMS TERM Has All Digits Complete Call
  • 11. Overlap or En-Bloc: Paper Analysis
    • En-Bloc is a RGW management issue
      • Local area dialling means that maps are region dependant
      • Number plan changes invoke reload of map
      • Network overlap is still required for (eg international) calls
    • Overlap versus open-bloc sending
      • Compare number Transactions & signalling load
      • But simulation necessary to ensure that IMS scaling is optimised from beginning
    • Collaboration with Waterford Institute of Technology
      • Use IMS Bench load simulator to load IMS with realistic user scenarios
      • Simulation of overlap sending is one such scenario
  • 12. IMS Bench
    • Conforms to ETSI benchmark IMS standard
    • Based on open source SIPp tool
    • Simulate client behavior
    • Distributed client for scalable load testing
    • Manager pushes test cases to distributed SIP’s over the network.
    • Synchronisation of scenarios between SIPPs
    • Agent enables monitoring of IMS load
    Manager SIPp 1 SIPp 2 SIPp N Sig. Agent IMS . . . Synch between Sipp Orchestration & Data Collection SIP IMS Test Traffic
  • 13. Overlap Simulation Pushes into overload: know our limits
    • How far can we push system before errors
      • What is impact on customer experience?
      • SBC throttling turned off here
    • Incorrectly Handled Scenarios are those which are outside operating parameters encompassing
      • Call flow, message formats, responsiveness timers, etc
      • .
  • 14. Sample Deployment Issue Understanding & Ensuring Voice Quality
  • 15. Experiments On Voice Quality
    • First line voice client is embedded in RGW
    • Start With Voice Quality Benchmarks
      • PSTN / PSTN is the benchmark
      • IMS / PSTN sets benchmark for A/D conversion in media gateway
      • IMS / IMS sets the benchmark for A/D conversion in residential gateway
    • Then Simulate Congestion and observe impact on
      • Upstream voice quality
      • Downstream voice quality
  • 16. Method To Test Voice Quality
    • Make call across network
    • DSLA injects audio into handset cord
      • Compare received with transmitted
      • Plot signal power against time
    • Many other reports
      • Gain versus audio frequency (1-3.4Khz)
      • Jitter analysis
      • Echo cancellation etc
    IMS Core Transit Layer & PSTN Gateway Phone Gateway Phone MALDEN DSLA TRANSMIT RECEIVE COMPARE
  • 17. Audio Stream IMS To PSTN: no congestion IMS Core Transit Layer & PSTN Gateway Phone Gateway Phone MALDEN DSLA TRANSMIT RECEIVE PESQ = 3.57 (Transmitted, Received, Error) Frequency Response Shows 6DB Loss
  • 18. Audio Stream Sent IMS To PSTN: no congestion IMS Core Transit Layer & PSTN Gateway Phone Gateway Phone MALDEN DSLA High Frequency Signal Loss In Media Gateway? TRANSMIT RECEIVE PESQ = 3.57 (Transmitted, Received, Error) Frequency Response Shows 6DB Loss
  • 19. IMS TO IMS: Voice Quality During ADSL Congestion
    • With No Congestion
      • PSTN To PSTN PESQ = 4.1
      • IMS To IMS PESQ = 4.2
    • Downstream not degraded
      • PESQ 3.5
    • Upstream connection lost
      • PESQ 1.1
      • Voice frames trapped behind data
    • (Voice Activity Detection Issue)
  • 20. Solution To Protect Voice Quality
    • Home Gateway sets DSCP for upstream packets
    • Voice packets scheduled out of gateway before Internet
    • Passed through access network in VLAN with Pbit set
    • VLAN – MPLS – VLAN mapping through access and core
    • SBC sets DSCP for downstream
    DSCP Marking HOME GATEWAY VLAN PBIT Optical VDSL MPLS EXP 7750 7750 7750 VLAN PBIT SWITCHES DSCP Marking IMS HOME ACCESS IMS ADSL ACCESS CORE
  • 21. Solution To Protect Voice Quality
    • Home Gateway sets DSCP for upstream packets
    • Voice packets scheduled out of gateway before Internet
    • Passed through access network in VLAN with Pbit set
    • VLAN – MPLS – VLAN mapping through access and core
    • SBC sets DSCP for downstream
    DSCP Marking HOME GATEWAY VLAN PBIT Optical VDSL MPLS EXP 7750 7750 7750 VLAN PBIT SWITCHES DSCP Marking IMS HOME ACCESS IMS ADSL ACCESS CORE Most Important Is That Voice Clocked Out Of Home Gateway Before Internet Traffic
  • 22. Softclient (WLAN) is Load Sensitive
    • IMS client running on iPhone
    • Without congestion PESQ is 4.4
    • When WLAN is loaded then
    • Downstream degraded first PESQ = 1.1
      • Because access point has no priority
      • Effectively One way transmission
    • Then Upstream Degraded
      • Voice packets delayed behind longer data packets
    • Congestion begins at low bit rate
    downstream upstream
  • 23. Can we Really Protect Voice on WLAN?
    • Candidate technology
      • 803.11e & Wifi Multimedia (WMM)
      • Short wait and backoff time for voice & AP
      • Timers broadcast to wireless devices
      • So traffic prioritised in both directions
    • Voice quality protected in light congestion
    • BUT: Is 802.11e feasible to deploy?
      • Supported by our gateway
      • Supported by our softclient
      • Not supported by all operating systems
    1 0 tx time n x 10 micro sec tx wait wait tx freeze 2 4 1 3 0 2
  • 24. Conclusion Tools To Enhance Call Quality
  • 25. Tools To Enhance Customer Experience Subscriber Data Mang Application Servers BSS OSS Circuit Switched Mobile IMS Core Transit Layer & PSTN Customers Web HLR IMS MSC MGC MG PRV SA RES NGIN ENUM HSS LEG MOB Client RGW PH MOD ISDN MGC SELF CARE IMS SIPT IPBX IM SIP INTER TOOLS
  • 26. Conclusion: Recommended Framework
    • IMS client simulation capability
    • Voice quality reporting
    • Active voice quality probing system
      • Across operators if motivation / agreement can be reached
    • Passive signalling load monitor
  • 27. Ancillary Slides
  • 28. Eircom Voice Call Continuity Trial Subscriber Databases Application Servers Provisioning Billing Alarms Circuit Switched Mobile IMS Core Transit Layer & PSTN Customers Web HSS VCC IMS MSC MGC MG RES ENUM HLR PSTN MOB Client PH
  • 29. Eircom Voice Call Continuity Trial Subscriber Databases Application Servers Provisioning Billing Alarms Circuit Switched Mobile IMS Core Transit Layer & PSTN Customers Web HSS VCC IMS MSC MGC MG RES ENUM HLR PSTN MOB Client PH - Lack of VCC Clients
  • 30. Eircom NGIN Integration & Web Exposure Trial Subscriber Databases Application Servers Provisioning Billing Alarms Circuit Switched Mobile IMS Core Transit Layer & PSTN Customers Web IMS MGC MG NGIN PSTN Client Browser Phone MS Outlook Google Maps
  • 31. Eircom NGIN Integration & Web Exposure Trial Subscriber Databases Application Servers Provisioning Billing Alarms Circuit Switched Mobile IMS Core Transit Layer & PSTN Customers Web IMS MGC MG NGIN PSTN Client Browser Phone MS Outlook Google Maps + OUTLOOK INTEGRATION FITS ENTERPRISE - GOOGLE MAPS APP WAS PURELY TECHNICAL EXERCISE
  • 32. IMS Benchmark: ETSI TS 186 008
    • Simulates the activities of individual users.
    • Use-cases describe the behaviour of an individual user, which, in turn, defines scenarios;
    • Benchmark tests generate a workload by aggregating the behaviour of individual scenarios & collecting measurements
    • Benchmark test reports that give metrics interpreted from the benchmark test logfiles.
    ScenarioSetup Scenario “Call Flows”
  • 33. Why Do We Have Post Dial Delay Issues?
    • Overlap sending from PSTN phone
      • RGW does not know number length
      • IMS does know number length for national & some international calls
      • Overlap sending is unavoidable for the rest
    • Static routing tables
      • IP routing tables update each other
      • Digit analysis tables are Isolated from each other
      • ENUM databases are not globally connected
  • 34. Mean Opinion Score
    • Conversational MOS shown
    • We calculated PESQ
    • And found
    • Good quality <200ms
    • Garbled 200-400ms
    • One way transmission
      • >400ms
      • Packet loss > 5%
  • 35. Strategy - Performance
    • Testing increases Scenario Attempts Per Second (SAPS) stepwise
      • E.g. From 30 Regs/s to >200 Call Attempts/s, increased by 20 SAPS every 5 minutes.
      • Poisson distribution used for scheduling, around mean (1/ SAPS) period
      • Range of tests will be considered, simulating typical user behavior: eg Overlap
    Activity Scenario Registration Initial with Auth De/Re-registrations Calls Successful Call of 1, 2, 5, 10 mins With[out] resource reservation Rejected Call Abandoned Calls Messages Successful - To Individual Successful - To Group Unsuccessful – User not found
  • 36. Simulation of Overlap Signaling Simulated SS7 <sample> random dialled d igits Statistically Distributed <pause> <recv timeout=“6000” ontimeout=“end”>
  • 37. Trials Versus Deployment
    • Trials
      • Input to product development process
      • Advanced features can be demonstrated
      • No back office integration
    • Deployment
      • Part of product development
      • Systems integration
      • Basic features
      • Rigorous testing
      • New issues emerge: basic user experience