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RRH-to-BBU Network Testing to Ensure Performance and Reliability

RRH-to-BBU Network Testing to Ensure Performance and Reliability. Presenter: Absolute Analysis. Agenda. 1 – RAN Evolution and Test Categories for RRH-To-BBU Networks 2 - Investigator Product Introduction 3 – Solving 5 Major 4G/LTE RAN Problems. Presenter/Corporate Info.

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RRH-to-BBU Network Testing to Ensure Performance and Reliability

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  1. RRH-to-BBU Network Testing to Ensure Performance and Reliability Presenter: Absolute Analysis

  2. Agenda 1 – RAN Evolution and Test Categories for RRH-To-BBU Networks 2 - Investigator Product Introduction 3 – Solving 5 Major 4G/LTE RAN Problems

  3. Presenter/Corporate Info About Absolute Analysis About The Presenter Position Experience, etc. Presenter Picture • Mission: Validate serial communications • In business since 1999 • Help customers test high speed systems in: • Telecom • Military • Data centers • Fully employee owned

  4. 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 Interoperability RRH RF Modulation Testing Performance Testing Multi-Technology Timing BBU to RRH Communications CPRI/OBSAI link BBU DWDM PON

  5. Visibility into the link is the key to testing the RAN CPRI or OBSAI Link BBU RRH IQ Data Command Protocol Vendor Specific

  6. The #1 LTE Hardware Integration Problem WHERE is my problem? RRH Team BBU Team Software Team Hardware Team RF Engineers DSP Engineers

  7. Section 2 InvestigatorProduct DescriptionRRH-to-BBU communications testing

  8. Who Uses Investigator?

  9. A Comprehensive High-Speed Serial Protocol Test System • 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 Investigator with mini-Portable Chassis

  10. Network Connection Options RRH RRH TAP BBU Optical Tap BBU Interpose Mode RRH BBU Cross Connect Switch

  11. 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

  12. Compliance Testing – Sync and Timing • SYNC and Timing • SYNC byte check • HFN Increment, range • BFN Increment, range

  13. Compliance Testing – L1 Inband • Link Maintenance Flags • Vendor Specific Area

  14. 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 Digital RF Data (IQ) in CSV, text, or MATLAB Fast C&M Data (.PCAP or CSV) BBU

  15. Vendor Specific Channels Decode Vendor Specific Area C&M Decodes

  16. Extract IQ Data Spectrum Graphs Constellation/EVM Measurements Time Domain Graphs • From IQ Data, plot RF using RF Analysis software tools

  17. Real-Time Performance Statistics UMTS • Performance Statistics • Loss of Signal (LOS) • Loss of Frame (LOF) • Service Port Access (SAP) defect indication (SDI) • Remote Alarm Indication (RAI) • Radio frame numbers • Protocol checks • HFN/BFN sequence errors • HFN range errors • Invalid BFN numbers

  18. 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: • Length: Cable length range: 2.4km to 40,000 km, resolution 7.6m • Delay: 10uS to 1 second RRH BBU

  19. 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

  20. Error Injector • Inject errors into the link to check error recovery algorithms • Checks include • Setting link maintenance flags • Inserting CRC errors

  21. Section 3 5 Case Studies RRH-TO-Bbu Communication Problems

  22. 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

  23. 1 – Solving Interoperability Example HFN/BFN incrementing properly? All CPRI/OBSAI parameters operating according to specification?

  24. 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.

  25. 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

  26. 3 - RRH-BBU Communication Problems Extract Fast C&M (Ethernet Channel) Data To Wireshark: Ethernet Command Data (PCAP) Captured Trace Data Captured Trace Data CPRI/OBSAI Data Extractor User Inputs

  27. RRH/BBU C&M Layer Example(TCP) 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?INTALMSTAT:INTALM=0X00200000,0X00000000 INTALM2=0X00000000,0X00000000 INTALM3=0X00000000,0X00000000?EXTALMSTAT:EXTALM=0X00000000?SIMULCAST:STATE=DISABLE?CPRIDESC:NUMCPRIPORT=2 PORT1MODES=0X0000000 Time: 11 40.146655 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

  28. 4 – Rx Interference Problems RRH BBU Traditional Network 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

  29. 4 – Rx Interference Problems RF to Digital RF (IQ) Correlation Test Set Up BBU RRH CPRI/OBSAI Link Investigator CPRI/OBSAI Protocol Analyzer 2 Way Trigger Signal Analyzer Correlated IQ Data IQ Data IQ Plots

  30. 5 - PON Performance Testing ROADM CPRI/OBSAI Across WDM (Distance to 50km) BBU BBU BBU Optical Terminal BBU BBU ROADM Macro Cells RRHs ROADM Baseband Pool Small Metro Cells 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.

  31. 5 - PON Performance Testing • Performance Measurements • Latency • Failover delay • Bit Error Rate • Find: • Cable disruptions • Slow devices • Misbehaving devices • Impairments ROADM CPRI/OBSAI Across WDM (Distance to 50km) Optical Terminal ROADM Macro Cells RRHs Investigator for Baseband side performance testing ROADM Small Metro Cells

  32. 5 - WDM Performance Testing Backup circuit Primary circuit ROADM CPRI/OBSAI Across WDM (Distance to 50km) Optical Terminal Switch ROADM Macro Cells RRHs Baseband Pool ROADM Small Metro Cells

  33. 5 - PON Performance Testing Latency Measurements Failover (Redundancy) Measurement Individual Port Measurements Traffic Test Pattern Selection

  34. Section 4 Future Development

  35. Future: Real-Time CPRI or OBSAI Link Monitoring RRH • Monitor RAN in real-time • RF Signal Strength • RRH/BBU Communication Status • Remote monitoring • Real-time alarms and triggering • Reduce tower support costs • Reduce delay to problem resolution CPRI or OBSAI Link BBU Central Monitoring Ethernet

  36. Future: RRH CPRI or OBSAI Link RRH Testing 9.8 Gbps Speed Packet Jitter Injection and Analysis Clock PPM monitoring RRH emulation for BBU testing BBU emulation for RRH testing

  37. Section 5 Demo

  38. Section 6 Q&A

  39. Section 7 Backup slides

  40. Investigator = Referee BBU Team RRH Team Hardware Team Software Team DSP Engineers RF Engineers Investigator

  41. The Business of PREVENTION and RECOVERY

  42. 2G to 4G/LTE Evolution: Multi-Technology LTE 2G 3G 2G 3G 2G Antenna RRH RRH CPRI or OBSAI link RF Digital RF LTE RRH W-CDMA BBU BBU Legacy 2G Technology 3G Evolution 4G/LTE

  43. 4G/LTE Evolution: Baseband Pooling RRH RRH Up to 10km BBU RRH Up to 60km 2G/3G RRH Baseband Pool RRH BBU BBU Passive Optical Network RRH BBU BBU BBU Next Generation

  44. Heterogeneous Network (HetNet) Evolution To Backhaul ROADM CPRI or OBSAI Across WDM (Distance to 50km) BBU BBU Optical Terminal BBU BBU ROADM BBU Macro Cells RRHs Baseband Pool ROADM Small Metro Cells

  45. LTE Radio Access Networks Testing Challenges • Limited RF signal availability • Only digital RF at the bottom of the tower • RRH separation makes it difficult to debug commands • Distance requires more performance testing of PON • Multi-technology introduces complex timing issues RRH CPRI/OBSAI link DWDM PON BBU

  46. Customize Protocol Decodes Most companies have CPRI or OBSAI customizations Insert your own CPRI decodes for display in viewer

  47. Impairment GUI Fibre, coax, twisted pair cable types Time or Cable Length Units in: Distance: feet, meters(m,km) Time: seconds (uS, mS, S) Bit Error Rate monitoring Transmitted frame count and link status

  48. Loss of Signal Debug Sequence Check Bit Error Rate to rule out physical layer issues. Capture trace around error conditions. Check trace for CPRI compliance Check trace for interoperability issues on RRH/BBU control layer Compare error condition traces with normal operation traces to find operational differences.

  49. RRH/BBU C&M Layer Example(TCP) 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?INTALMSTAT:INTALM=0X00200000,0X00000000 INTALM2=0X00000000,0X00000000 INTALM3=0X00000000,0X00000000?EXTALMSTAT:EXTALM=0X00000000?SIMULCAST:STATE=DISABLE?CPRIDESC:NUMCPRIPORT=2 PORT1MODES=0X0000000 Time: 11 40.146655 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

  50. RRH Cross Trigger BBU Traditional Network Investigator

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