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393575910-318163030-E2E-VOLTE-pptx.pptx

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393575910-318163030-E2E-VOLTE-pptx.pptx

  1. 1. I Copyright © 2016 Tech Mahindra. All rights reserved. 1 E2E Volte optimization- Offerings & Capabilities Planning & implementation 1 KPIs 3 Challenges of implementation 4 Testing & Tools 2
  2. 2. I Copyright © 2016 Tech Mahindra. All rights reserved. 2 Introduction to VOLTE  LTE is a packet only architecture designed to improve data performance. It does not support CS voice or video call.  In order to accommodate voice on LTE, two approaches were taken i.e. CSFB(Circuit Switch Fall Back) and Volte.  GSMA – Voice over LTE has evolved as the preferred standard for telephony solution in LTE that has been accepted by the operator community.  GSMA has defined Voice over LTE (Volte) in describing minimum set of requirements for delivering voice in an all IP environment based on existing 3GPP IMS based multimedia telephony solution. LTE Voice Solutions Voice and Data Services Provided By the LTE Network Data Services Provided By the LTE Network and Voice Services Provided By the CS Network IMS/SRVCC(Voice Solution Provided by IMS and Data by LTE EPC.LTE Subscribers can Roam on 2G/3G network by SRVCC Voice Services are Provided by OTT(Over the Top Content Delivery of Audio and Video Over Internet with help of ISP) Carrier Voice Services Provided by CSFB (Subscribers Fall back to Traditional 2G/3G Networks) SVLTE: Dual Radio Terminals are required ,the 2G/3G Network Provides Voice services and LTE Provides data
  3. 3. I Copyright © 2016 Tech Mahindra. All rights reserved. 3 VoLTE Phase-based Deployment Policy(Planning) LTE LTE 2G/3G LTE 2G/3G LTE 2G/3G Phase 2: Continuous LTE coverage Phase 1: Hot spot LTE coverage Phase 3: Full LTE coverage Pre-VoLTE Initial commercial use Large-scale commercial deployment  Terminals:  Initial smartphone  LTE data card and LTE CPE(Customer premises equipment (CPE)  Deployment suggestions:  CSFB  CPEs subscribe to IMS-based VoIP voice services.  Soft clients subscribe to rich media RCS services(Rich Communication Services) program is a GSM Association (GSMA) .  Terminals:  Smartphone  LTE data card and LTE CPE(Customer premises equipment (CPE))  Deployment suggestions:  IMS-based VoLTE voice services  eSRVCC  Convergent database SingleSDB  LTE-based rich media RCS services  Terminals:  Smartphone  LTE data card and LTE CPE(Customer premises equipment (CPE))  Deployment suggestions:  The LTE network becomes the mainstream.  ICS(IMS Centralized Services)  IMS roaming and interworking
  4. 4. I Copyright © 2016 Tech Mahindra. All rights reserved. 4 Overview of the Data collection Using Wireshark and TEMS Discovery TI Logs MME Traces collected 1) TI-Logs are Terminal Logs or UE Logs Collected during drive test and Analyses Using Tems Discovery Like RRC Failure Analysis and L3 Message Analysis 2) 2)As a Part of Enode B Performance Analysis Wireshark Logs Collected at MME on S1 AP,X2 AP to analyse the Performance issues happening on SIP protocols to identify UE and ENodeB Performance issues
  5. 5. I Copyright © 2016 Tech Mahindra. All rights reserved. 5 High level Troubleshooting Guide For Performance Analysis Collect Data Analyze UE Layer 3 RF Correlation Found? Correlate with Traces Evaluate in detail Evaluate SIP Log IMS Correlation Found? Evaluate in detail Potential MME/EPC Issue? RAN ISSUE CORE ISSUE Cascade to E2E Team YES NO NO YES  Trouble Shooting to Improve Volte Performance are done Via Drive Test Logs an Logs Collected at MME  Access ability and Retain ability are two main KPIs for LTE Layer 3 Analysis. Tems Discovery Volte report also provides LTE RRC KPIs like RRC Setup Failure Rate, RRC Setup Attempts, RRC Setup Complete, RRC Drop Rate, RRC Calls Successfully Completed, RRC Drops, etc.  Wireshark Logs an Helps to Find out NON-RF issues like SIP Protocols Issues, Core Network Issues
  6. 6. I Copyright © 2016 Tech Mahindra. All rights reserved. 6 VOLTE Log Analysis Using Wireshark(SIP Messages) UE Registration with IMS The Above Snap shows the analysis of Packet Capture for SIP Messages done on ENodeB to MME S1 –AP Interface analysis done using wireshark.The Log shows the UE is Registered in Volte Domain(registered with IMS) and IMS AKA- Authentication(Authentication and Key Agreement) has been Completed by Core Network and UE is Ready to make Volte Calls
  7. 7. I Copyright © 2016 Tech Mahindra. All rights reserved. 7 RRC(L3) Analysis Procedure from Tems Discovery The Above Snap shows the analysis of UE logs collected during drive test and analyzed using Tems discovery, the L3 analysis above shows that the UE is started reading the System Information messages and ready for registration to LTE network
  8. 8. I Copyright © 2016 Tech Mahindra. All rights reserved. 8 LTE/VOLTE COUNTER KPI’S & THRESHOLD LTE Counter KPI'S for 10 MHz KPI Target % Accessibility >99% % Retainability > 99 % % HOSR > 98.5 % % IRAT Rate < 1% DL Throughput (Mbps) > 11 UL Throughput (Mbps) > 5 CSFB Succ Rate > 98.5 % VOLTE Counter KPI'S KPI Target % Accessibility QCI1 >99% % Retainability QCI 1 > 99 % % HOSR QCI1 > 98.5 % %SRVCC Succ Rate > 98.5 % LTE OSS KPI’s Volte OSS KPI’s VOLTE Drive KPI KPI Threshold VOLTE MO Accessibility >99% VOLTE Retainability >99% VOLTE MO Retainability >99% VOLTE MT Retainability >99% VOLTE MO Voice Setup Time <8.5 sec VOLTE MT Voice Setup Time <3.5 sec % of Samples with MOS>2.1 > 98 % % of call stayed on VOLTE >96% VOLTE Drive Scenario MS1 LTE_Scanner MS2 Long Call DL (DO only) MS3 Long Call UL (DO only) MS4 MO CSFB Call MS5 MT CSFB Call MS6 VOLTE MO UE MS7 VOLTE MT UE Volte Drive Test KPI’s
  9. 9. I Copyright © 2016 Tech Mahindra. All rights reserved. 9 VOLTE OPTIMIZATION(Drive Test and OSS Statistics)  Volte Performance can Analysed by Drive Test data and OSS Statistics  The purpose of VOLTE drive test is to evaluate the coverage and performance of a network for voice call services. The Major VOLTE drive test parameters are as RSRP, SINR, DL RSSI, MOS Score, RSRQ, UE TX Power etc.  Techmahindra has to perform few basic checks with drive logs and parameter audit sheets like : Site are not radiating or radiating with poor footprint, Antenna Swap, MIMO Swap, PCI Collision, Alarms, UL RSSI, VSWR, Cell Status, eNodeB Power and check for Parameter.  Session setup success (Accessibility), session completion failure (Retainability) and SRVCC success rate are two main KPI’s for analysis from Drive Test data and OSS Stats  With the help of drive test data and OSS Stats, Techmahindra can check below points: – Coverage footprint of sites – Accessibility – Retain ability – Mobility – Quality – MOS Score – SRVCC  If Any degradation in any drive KPI, then has to find out RCA and has to provide solution as per specific problems. Please find some basic troubleshooting and recommendation for improvement of drive KPI in next slide:  SRVCC - SRVCC is the Main KPI which needs to be Optimized when there is no Volte Coverage When the handset leaves the LTE coverage area, then VOLTE connection can be handed over to a CS connection in a legacy network. This procedure is called SRVCC (Single Radio Voice Call Continuity). If LTE coverage is extensive, then SRVCC probability is Low. It is beneficial to have a low SRVCC probability to gain full benefit of VOLTE. If SRVCC issue observed, need to check for A2 and B2 thresholds of QCI 1. Check for neighbor relations for SRVCC with legacy network
  10. 10. I Copyright © 2016 Tech Mahindra. All rights reserved. 10 VOLTE OPTIMIZATION(Flow Chart for Accessibility) START Call Access Failure? Yes HW Fault /Down Time? Check Hardware Fault (RRU, Neighbor Cell fault or down), Check current alarm, History & Activity logs Yes NO is Accessibility fail to Due o High/LOW RSSI Yes Check Media, S1 continuity, Tempoint status. NO Is Fails due to Poor RF Check PCI Collision, Interference (UL RSSI), overshooting and Hardware As Fails due to Congestion? Yes Try to offload Cell/Site, Apply Layer management strategy if multicarrier carriers available, Apply Hi Cap settings & Do possible Physical Optimization. Fails due to Other Reasons? Check for any Non RF Ready Or Pre launch sites nearby, Check layer management strategy for Multicarrier sites, need to check core Network issues by UE traces or MME traces analyzed using Wireshark. END Yes Identify Poor RF Coverage, Check CQI & Power Limitation. Recommend Physical Optimization of cells or Propose New Coverage sites. Check for faulty antenna, High VSWR, damaged cables or connectors. Yes Tx Fault? NO NO NO
  11. 11. I Copyright © 2016 Tech Mahindra. All rights reserved. 11 VOLTE OPTIMIZATION(Flow Chart for Retainability) START Call Drop? Yes No HW Fault /Down Time? Check Hardware Fault (RRU, Neighbor Cell fault or down), Check current alarm, History & Activity logs Yes NO Is Drop due to HO Fail Or High UL RSSI? Yes Check Media, S1 continuity, Tempoint status. NO Is Drop due to Poor RF Check PCI Collision, Interference (UL RSSI) on target cell, overshooting Check UL RSSI on cell. High Interference cause drops. Is Drop due to Congestion? Yes Try to offload Cell/Site, Apply Layer management strategy if multicarrier carriers available, Apply Hi Cap settings & Do possible Physical Optimization. Drops due to Other Reasons? Check for any Non RF Ready Or Pre launch sites nearby, Check layer management strategy for Multicarrier sites, need to check core Network issues by UE traces or MME traces analyzed using Wireshark. END Yes Identify Poor RF Coverage, Check CQI & Power Limitation. Recommend Physical Optimization of cells or Propose New Coverage sites. Check for faulty antenna, High VSWR, damaged cables or connectors. Yes Tx Fault? NO NO NO
  12. 12. I Copyright © 2016 Tech Mahindra. All rights reserved. 12 VOLTE OPTIMIZATION(Flow Chart for Mobility ) START Poor HO Preparation Yes NO NO Overshooting Yes END NO Incorrect Parameter setting in Target Term point to MME missing on target cells. Check if all MME link is working if MME is in Pool. Check for Overshooting cells with drive plots/Prach Report ,Recommend Physical Optimization of these cells and parameter optimization to restrict the Cell footprint. Propose Coverage optimization for sites having coverage holes. Target cell might be loaded Handover preparation may fail because the target eNodeB cannot provide the necessary resources for the handover during congestion or cannot interpret the contents of the handover request message. Check Ho Parameters and Call traces with log analysis to check the incorrect parameter NO Alarm in the target Check for X2Failure alarm or S1 Failure alarm in The target cell Yes Yes NO NOO Yes NO Collectogs on X2 and S1 AP Analyse using Wireshark and check for the Cause
  13. 13. I Copyright © 2016 Tech Mahindra. All rights reserved. 13 S. N Problem Description Troubleshooting Solution 1 TX Imbalance If Both the Tx branches of Antenna or RRU are not dominant in same direction, it is refered as Tx Imbalance, (Difference between two TX branches < 10db). It can we verified with scanner Tx1 & Tx2 RSRP plot in Tems discovery to see that the difference between TX1 and TX2 rsrp should not exceed 10db. Inform customer so that the tower crew can be sent to site for rectification. 2 Feeder Swap Feeder cables are physically incorrectly connected between the RRU and Antenna. PCI plot need to be checked on Tems discovery to see if the sectors are radiating in the expected direction. Inform customer so that the tower crew can be sent to site for rectification. 3 Azimuth Issue If existing orientation of antenna are different from the designed azimuth. PCI distribution need to be check in PCI Plot. PCIs are shifted either clockwise or anti clockwise with respect to the azimuths Inform customer so that the tower crew can be sent to site for verification. 4 Accessibility Issue Poor Accessibility observed during Drive Test Need to Check PCI collision. Check for UL RSSI, Check for coverage, check for Alarm, check for License capacity. Check for SIP call flow, there can be several reason observed from SIP messages. Fix the problem after implementation of recommendation on the basis of analysis. 5 Retainability Issue Poor Retainability observed during drive test Check for coverage, Check for PCI collision, check for UL RSSI, check for handover parameters. Check for SIP call flow. If there is no RTP packet for 10 sec then it will pegged a drop. Fix the problem after implementation of recommendation on the basis of analysis. 6 HO Failure During the mobilty test when UE tries to Handover from one PCI to another PCI and it got failed. Need to check the neighbor definition and check for ANR parameters as well. Need to check the basic Handover Parameters. Fix the problem after implementation of recommendation on the basis of analysis. 7 MOS Score Issue Poor MOS Score (<2.1) Need to check RF conditions. Check for UL RSSI, Alarms, VSWR and verify for codec rate etc. . Fix the problem after implementation of recommendation on the basis of analysis. VOLTE OPTIMIZATION CASE STUDIES during Drive Test
  14. 14. I Copyright © 2016 Tech Mahindra. All rights reserved. 14 Challenges To Deploying VoLTE The “flipside” of being able to deliver voice and data over one network is that those networks must now be optimized for both voice and data. Delivering high-quality voice is more challenging, and doing so in the form of data packets even more so. Aside from the sheer novelty of this undertaking, VoLTE involves lots of new moving pieces, unproven technologies, and interdependencies. Major challenges to ensuring successful Deployments out of the gate include:  Validating New Devices and Configurations By 2016, ARC Chart expects the installed base of Volte-enabled handsets to top 74 million. Such devices are already available in Korea and other countries leading adoption. Expects to see many more devices available in many more countries by the end of 2014, and all of these new devices need to be evaluated for performance, interoperability, and reliability.  Interoperability in Increasingly Multi-vendor Environments the interfaces involved in Volte are also prone to customization by vendors, including critical Diameter protocols used in the EPC core, and Session Initiation Protocol (SIP) implementations within IMS.  Signaling Spikes in hard-to-predict signaling traffic are already occurring due to smartphones generating up to 20x the signaling traffic of traditional phones. Signaling volumes may actually overwhelm infrastructures, leading to costly and embarrassing outages.  Fallback Volte is not a forklift upgrade; it’s a whole new deal. Until every mobile phone in use supports it, operators will need to support legacy air-links and provide seamless fallback to 2G/3G networks where LTE is unavailable.  Ensuring Quality of Experience (QoE) For Volte to be worth the formidable investment, it not only has to deliver better quality than what OTT players provide, but exceed what 2G/3G networks deliver as well. Early indicators  Impact on value-added services What impact will increased complexity have on features like Call Waiting, forwarding, voicemail, and conferencing? In migrating voice to LTE, operators need to be sure subscribers’ satisfaction with the features they’ve come to rely on won’t be compromised  Stress / Scalability Does voice get prioritized effectively as the network become stressed? Where are the new bottlenecks and congestion points? What happens when failovers occur? QoS and reliability must be assessed under realistic load and high-stress conditions to ensure satisfaction and bring high-risk surprises to light before they do damage.
  15. 15. I Copyright © 2016 Tech Mahindra. All rights reserved. 15 VOLTE – Key Optimization CHALLENGES Metrics Characteristics impacting VoLTE KPIs Impacted HO Performance HO interruption time > 200 ms HO Oscillation – In poor RF conditions/cell edge Delayed/dragged HO – Slow fading signal HO failures Retainability Accessibility MOS Score DL SINR Degraded SINR - < 5 dB High traffic sites impact overall DL SINR SINR degradation during dragged HO – Intra/Inter Frequency Retainability Accessibility MOS Score Multi-RAB throughput & MBB Throughput Core/IMS Issues Packet loss and jitter – Non RAN related Systemic Issues – Control Plane related Functional aspects Retainability Accessibility MOS Score Call set up time UL RSSI UL RSSI > -110 dBm High packet loss Consistent RACH failures Retainability Accessibility MOS Score Coverage/RSRP - SRVCC Low RSRP levels Fall back to UMTS – impacts perceived end user call quality MOS Score Retainability

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