Link Master for VoLTE

Transcription

1 Link Master for VoLTE

2 CONTENTS. VoLTE Service Preparation and Commercialization in Major Operator.... VoLTE quality measurement method Test configuration VoLTE service quality report with auto call test VoLTE service quality report Call statistics report KPI report... 0

3 . VoLTE Service Preparation and Commercialization in Major Operator Before commercialization Samsung released st VoLTE smartphone (Samsung Galaxy S) on Q 0, and Operator started VoLTE test During Q and Q4 0, Operator found various problems in mobile and SIP server system Problem identified and solved with Link Master TM Mouth to ear delay was too long requirement: < 00msec, test result: > 900 msec reason: VoLTE AMRWB codec runs as software (AMRNB of UMTS call runs as hardware), and encoder/decoder took too long Operator (mobile phone quality assurance team, core network team, and VoLTE service development team), Samsung and Link Master TM team coworked to identify reason Below sample shows one of test result with Link Master TM. Link Master TM identified delay comes from AMRWB codec software, and Samsung improved it. Speech input Speech output 65 msec AMRWB encoder AMRWB decoder 76 msec UDP Tx UDP Rx 46 msec MAC MAC msec LL LL RF RF enb 08 msec msec Core enb Silence after HO, and call drop Another problem was silence after handover. After handover, there was no speech occasionally. With Link Master TM, Operator completed drive test with VoLTE auto call test and MOS measurement, listening to the speech in realtime using Link Master TM. They didn t watch the laptop, but could figure out immediately. They could hear handover occurred alarm, and no sound was played. By analysis with Link Master TM, they found no RTP packet was received after handover. Also, when there is no RTP packet to mobile, SIP server disconnects VoLTE session because of the charging issue. Together with system vendors (Samsung, NSN, Ericsson), Operator upgraded system package. Jitter/Loss/Delay KPI establishment

4 There was no KPI standard for jitter, loss, or delay for UMTS CS call. However, Operator had to establish new KPI standard Link Master TM team and Operator coworked to check voice quality(mos) with various combination of jitter, loss, and delay environments. (Jitter: 0~00msec, loss: 0~40%, delay:0~,000msec) After test, Operator established as below; Jitter: < 80msec Loss: < 0% Delay: It doesn t affect to the MOS, but it affects mouthtoear delay. Mouthtoear delay should be less than 00msec. Correlation between RTP jitter/loss and voice quality VoLTE uses AMRWB, which provides a clearer speech conversation. In the beginning of the deployment, engineers expected that if they keep RTP jitter and loss to certain threshold, voice quality(mos) will be maintained to high. Operator verified MOS using Link Master TM, and found that MOS can be low even though RTP jitter/loss is good. It means that RTP jitter/loss and MOS has a correlation, but not always There can be various reasons, but main reason is assumed to be in mobile side. Operator and Samsung are still coworking to clear this issue. Unexpected BYE message from network Even though none of mobile released the call, Operator found occasional VoLTE call drops. With Link Master TM, Operator analyzed SIP message and found unexpected BYE messages are received from network. Almost all of BYE message includes cause = QoS Service Unavailable. Operator coworked with network vendors and SIP server, and updated package. After package update, the probability went down a lot. BSR (buffer status report) During test with Link Master TM, Operator found unexpected VoLTE call drop occurs With Link Master TM, Operator monitored BSR. There are three kinds of UL BSR events; Periodic, High Data Arrival, and Robustness. Operator found there are unexpected robustness events, and it causes VoLTE call drop. With help of system vendor, SKT updated package and solved this issue. After commercialization Monitor and keep VoLTE KPI Operator is making field measurement every day in various area, using Link Master. They check various KPI values, and monitor the variation to keep to reasonable level. Voice quality(mos) measurement To keep VoLTE service quality, Operator checks MOS with Link Master TM. This is done by many engineers every day in various regions. VoLTE uses AMRWB, and Link Master TM can measure WB(wideband) speech quality using POLQA. POLQA is ITUT P.86 standard algorithm, which provides WB MOS calculation and mouthtoear delay.

5 . VoLTE quality measurement method.. Test configuration Link Master TM LML Laptop or Smart PC GPS Two mobiles for MM VoLTE test Link Master TM VoLT Link Master TM LML LTE signaling message(rrc, NAS) and TCP/IP packet data logging/analysis LTE data service quality measurement, with auto call test (FTP, iperf, etc.) LTE VoLTE service quality measurement, with auto call test LTE CSFB service quality measurement, with auto call test Link Master TM VoLT Qualcomm chip doesn t provide VoLTE call control function (origination, answer, release) LML can control VoLTE call using Bluetooth which is embedded in Link Master VoLT hardware Link Master VoLT also supports QoE(voice quality) measurement, through earjack cable with two mobiles.. VoLTE service quality report with auto call test For wide area VoLTE service quality measurement, auto call test is required. SKT can make daily/weekly/monthly reports, which include various KPIs including VoLTE call statistics, MOS statistics, SIP setup time, RTP jitter/loss/delay statistics, radio quality(rsrp, RSRQ, Tx power, SINR, HOIT, HO count, CQI, etc.)

6 Sample KPI

7 . VoLTE service quality report.. Call statistics report Below sample shows call statistics report sample, which includes VoLTE, CSFB, and data service measurement results. 0.7 LTE Service Quality Report Area Seoul KangNam Date Call statistics summary LTE VoLTE LTE CSFB WCDMA Voice Success Drop Bad Speech Quality Time Operator 98.00% 00.00% 0.00%.00%.76 Operator 98.66% 00.00% 0.67% 0.68%.7 Operator 00.00% 00.00% 0.00% 0.00%.69 CSFB Ratio (%) 98.00% 98.00% 0.00% 0.00% % 00.00% 00.00% 0.00% 0.00% % 98.67% 98.67% 0.00% 0.00% % 99.% 0.00% 0.00% % 00.00% 0.00% 0.00% 4. Data Success Trasnfer Throughput

8 LTE (Down) WCDMA (Down) WiBro (Down) LTE (Up) WCDMA (Up) WiBro (Up) KT 99.46% 00.00% 99.46% % 00.00% 98.9% % 00.00% 00.00% % 00.00% 98.69% % 00.00% 99.8%.0 99.% 99.6% 99.6% % 98.46% 98.05% % 00.00% 00.00% % 00.00% 99.46% % 00.00% 00.00% % 00.00% 00.00% % 00.00% 96.77% % 98.84% 00.00%.7 94.% 97.68% 96.44%.6 Call counts LTE_VoLTE LTE VoLTE Try Success Fail Drop BS(Bad Speech) BQ CBQ BS Comment

9 LTE_CSFB LTE CSFB Try Success Fail Drop BS(Bad Speech) BQ CBQ BS CSFB Calls CSFB Fail G Fail WCDMA_MM WCDMA Voice Try Success Fail Drop BS(Bad Speech) BQ CBQ BS Comment LTE Data (Down) Try Success Fail Trasnfer Try FTP Down Transfer Trasnfer Incomplete Throghput (Mbps) Traffic Fail Comment WCDMA Data (Down) Try Success Fail Trasnfer Try FTP Down Transfer Trasnfer Incomplete Throghput (Mbps) Traffic Fail Comment FTP Up Comment

10 LTE Data (Up) Try Success Fail Trasnfer Try Transfer Trasnfer Incomplete Throghput (Mbps) Traffic Fail WCDMA Data (Up) Try Success Fail Trasnfer Try FTP Up Transfer Trasnfer Incomplete Throghput (Mbps) Traffic Fail Comment KT KPI report Below sample shows KPI report sample, which includes VoLTE, CSFB, and data service measurement results. 0.7 LTE Service Quality Report KPI Area Seoul KangNam Date Radio Quality LTE VoLTE MM Radio quality Delay duration MOS RF class RSRP RSRQ Tx Power H/O Cont SINR CQI RTP Loss (%) RTP Delay (ms) RTP Jitter (ms) HO Latency (ms) SIP (80Rin g) SIP (00OK ) SIP (Traffic Start) QCI Avg Orig Term Class Class Class % % 47.5% 9.84% % % 44.9% 0.4%

11 % % 60.4%.64% CSFB/WCD MA Voice RSSI RSCP Radio quality Delay CSFB MOS WCDMA MOS RF class Ec/I o Tx Power Active PSC WCDMA LTE S S S S4 Avg Orig Term Avg Orig Term Class Class Class % 0.04%.98% % 8.4%.98% %.96% 0.49% LTE PS Down Radio quality RSSI RSRP RSRQ Tx Power BLE R Data Service Quality MCS Down Throughput (bps) Time CellID Co. PCI Co. SINR CQI Retrans RB RANK 64QAM 6QAM QPSK > 0M 0~0M 5~0M < 5M % % 45.78% 4.4% 9.8% 7.55% 4.88% 7.88% 9.69% % % 57.% 9.68%.09% 44.0%.7%.87% 8.46% % % 5.06%.7% 7.% 7.87% 46.76%.87%.5% LTE PS Up RSSI RSRP RSR Q Radio quality Tx Power BLE R Data Service Quality MCS Up Throughput (bps) Time CellID Co. PCI Co. SINR CQI Retrans RB RANK 64QAM 6QAM QPSK > 0M 5~0M.5~5M <.5M % 0.% 99.5% 0.75% 9.9% 5.5% 0.46% 0.07% % 0.% 95.5% 4.49% 70.47% 9.5% 5.4% 4.97% % 0.% 99.% 0.69% 9.0% 6.4% 0.50% 0.4% WCDMA PS Down Radio quality Data Service Quality MCS Down Throughput (bps) Time RSSI RSCP Ec/Io Tx Power CQI Retrans No of Codes 64QAM 6QAM QPSK > M 5K~M 56~5K < 56K % 8.47% 6.6% 78.79% 0.7% 5.5% 5.5%

12 % 5.8% 58.56% 84.5% 8.89%.48%.48% WCDMA PS Up Radio quality Data Service Quality MCS Up Throughput (bps) Time RSSI RSCP Ec/Io Tx Power CQI Retrans No of Codes 64QAM 6QAM QPSK > M 5K~M 8~5K < 8K % 0.0% 99.99% 75.9% 6.44% 5.95%.% %.0% 98.97% 8.74% 8.% 4.5%.69%

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