ATSC 3.0 Single Frequency Broadcast Network Experience in the Republic of Korea Sungho Jeon, Seong-Man Min, Dawoon Chung, Kangsoo Kim, Jahoon Ku, and Kyungbok Lee July 19, 2023 (Session 2) Current & Future Korean BroadcastingSystem | Department of MediaTransmission Global Digital Terrestrial Transmission Workshop 2023 @ Busan, South Korea

ATSC 1.0 T-DMB ATSC 3.0 Mobile(SD) Multi-channel Datacasting High-definition TV Second-generation terrestrial broadcasting system First-generation terrestrial broadcasting system + → 1TV Simulcast 2TV Simulcast Visual 2FM EWS Emergency Warning Service TPEG Traffic information 9-3 Visual 1Radio (suspended) 9-1 KBS1 UHD 9-2 KBS disaster-focused channel IBB Interactive Service Visual 2FM KBS NEWS24 Ultra HD + Interactive Mobile HD/MMS/Datacasting AEAT Emergency Alert Service By deploying only one ATSC 3.0 system, various services are available DATA 7-1 KBS2 UHD AEAT Emergency Alert Service DATA

700MHz frequency band 470–698MHz DTV frequency band KBS2, EBS KBS1, MBC, 지역민방 Seoul Daejeon Jeonju Gwangju Cheongju Busan Ulsan (2020.12.) UHD broadcasting network expansion in progress according to new Korean government policy plan ATSC 1.0 DTV switch-off 2020 2019 2021 2027 2023 2022 UHD innovation service (multi-channel/mobile/interactive) start 2017 World's first ATSC 3.0 terrestrial UHD broadcasting started 2017.05. 2017.12. 2017.12. 2017.12. 2017.12. Daegu 2017.12. 2023. Q3. 2023. Q3. Jeju 2022.02. Continuous expansion of service area Changwon Chuncheon 2024. Q1. 2024. Q1.

(2020.12.) UHD broadcasting network expansion in progress according to new Korean government policy plan

2 3 3 2 3 2 3 1 1 1 1 1 1 1 2 2 2 2 2 1 2 2 2 2 3 2 2 3 3 3 3 2 3 2 2 2 2 2 3 3 3 3 3 3 3 3 3 4 3 2 2 1 1 2 1 2 1 2 2 4 5 2 3 2 3 3 A coverage prediction map of ATSC 3.0 service simulated with a planning tool. (2020.12.) UHD broadcasting network expansion in progress according to new Korean government policy plan

A/78:2007 ATSC Recommended Practice: Transport Stream Verification

TR 101 290 Measurement Guidelines for DVB Systems PCR monitoring A/78a ATSC Recommended Practice: Transport Stream Verification Priority of faults Priority 1 : TS sync loss, Sync byte error Priority 2 : Transport error, CRC error Priority 3 : NIT error TOA (transport stream off-air) POA (program off-air) CM (component missing) QOS (quality of service) TNC (technically nonconformant) Key Monitoring Indicator by the First-Generation Terrestrial Broadcasting Standard

Terrestrial broadcasting system structure as defined in the ITU Handbook Note that with the advent of advanced 2nd generation transmission and modulations systems an additional block is to introduced between service multiplex and transport, the so-called Gateway. 1st Generation Terrestrial Broadcasting System Exciter Exciter 2nd Generation Terrestrial Broadcasting System ITU-R Rec. BT.1877 ITU-R Rec. BT.1306

IBC KBS KBS Transmitter #3 Transmitter #3 Transmitter #1 GPS ATSC3.0 Exciter GPS ATSC3.0 Exciter GPS Broadcast Gateway PTP ✓ SFN requires all devices to “use (synchronize) the same clock” based on GPS signal or PTP time. ✓ All transmitters must parse the Timing Packet and Preamble Packet among the input signals and set the transmitter to the same value. = Transmitter must be set by using STL Interface Transmission parameters are not set in individual transmitters ∴ All transmission parameter settings are ONLY on Broadcast Gateway! GPS ATSC3.0 Exciter SFN Condition #2 Same Time SFN Condition #1 Same Data SFN Condition #3 Same Frequency * PTP = IEEE1588v2 PTP(Precision Time Protocol) ATSC 3.0 Single Frequency Network

Master Control Room IP Broadband Microwave ATSC 3.0 Transmitter STLTP /RTP/UDP/IP STLTP /RTP/UDP/IP RF Broadcast Gateway Target equipment L2/L3 Switch Exciter ATSC 3.0 UHDTV Major monitoring items ✓ PTP SYNC Error ✓ BGW output stability Related standard A/324 A/322 ✓ Switchport Shutdown TTAK.KO-07.0154 PTP/UDP/IP ✓ RF MUTE (off-air) ✓ GPS SYNC error ✓ SFN Golden Rules . Packet Sequence Error (Packet Drop) . Network Delay exceeding tolerance range . Frequency Stability GP S SFN Transmitters ATSC 3.0 Transmitter ATSC 3.0 Transmitter ATSC 3.0 Standard Document and Key Monitoring Indicators at Each Analysis Point

BGW (A) BGW (B) IP-C/O L2/L3 Switch (A) L2/L3 Switch (B) Exciter (A) Exciter (B) TACU ATSC 3.0 Television Master control room Broadband IP Network (Point A) STLTP Microwave L2/L3 Switch (A) L2/L3 Switch (B) Remote device synchronized by PTP RF On-air (Point A) STLTP (Point B) RF Remote device synchronized by GPS PTP GPS Transmission site Central server collecting data JSON over VPN JSON over VPN ATSC 3.0 measuring Points A(STLTP), and B(RF) and corresponding inputs to the monitoring device

JSON Format for Exchanging STLTP and RF Measurement JSON Format for STLTP Measurement JSON Format for RF Measurement

Front Panel Rear I/O ✓ STLTP Monitoring • Network Delay • Maximum Network Delay • Packet Sequence Remote device synchronized by GPS or PTP ✓ RF Monitoring • RSSI • SNR • MER ✓ GPS Monitoring Front Panel Rear I/O GPS PTP

Remote device synchronized by PTP Remote device synchronized by GPS Remote monitoring devices installed at each point on the dashboard

{"pushkey":"","status":{"rf":{},"dstp":[{"plp_id":0, "plp_bitrate":1166832,"lls_bitrate":18512,"lls_bsid" :1041},{"plp_id":1,"plp_bitrate":16577184,"lls_bitra te":18512,"lls_bsid":1041}],"service":[],"recovery": [],"error":[],"event":[],"device":{"device_ip":"192. 168.104.122","rf_status":99,"total_bitrate":18410410 ,"error_state":0,"utc_dt":"2020-11-11 01:36:03.175","net_input_status":1,"timesync_state": 1,"leap_second":37,"local_dt":"2020-11-11 10:36:03.175","power_alarm":1},"stltp":{"stl_fec_sta te":"4x8","stltp_ip":"239.255.9.30","txid_seed":"1", "network_delay_min":"4.8","stltp_port":5000,"network _delay_now":"9.2","max_net_delay":"599.8","packet_dr op_count":0,"wakeup_bit":"00","stltp_bitrate":184104 10,"l1d_bsid":1041,"l1d_version":1,"network_delay_ma x":"23.0","stl_fec_repair_count":0,"txid_injection_l vl":"21.0","txid_group":0}}} Remote monitoring device transmits measurement values in JSON format every second DB Server WEB Server ✓ Data collection and system integration ✓ Analysis of collected monitoring data Example of JSON specification for collecting data from central data collection server configuration and remote monitoring device

✓ MND ≥ actual network delay + transmitter processing delay: RF OK ✓ MND < actual network delay + transmitter processing delay: RF Mute Transmitter #2 Processing Delay Buffer at Exciter Network Delay Transmitter #1 Processing Delay Buffer at Exciter Network Delay Network 1 Network 2 Transmitter 1 Transmitter 2 Packet Release Time Bootstrap Emission Time • • • Packet 3 Packet 2 Packet 1 Packet N BGW Signaling ATSC 3.0 BGW 2018 Scheduler / Studio to Transmitter Link 5 January 2018 Table 8.3 Timing and Management Stream Packet Payload Syntax No. of Bits Format Timing & Management_Packet (TMP) () { Structure_Data () { length 16 uimsbf version_major 4 uimsbf version_minor 4 uimsbf maj_log_rep_cnt_pre 4 uimsbf maj_log_rep_cnt_tim 4 uimsbf bootstrap_major 4 uimsbf bootstrap_minor 4 uimsbf min_time_to_next 5 uimsbf system_bandwidth 2 uimsbf bsr_coefficient 7 uimsbf preamble_structure 8 uimsbf ea_wakeup 2 bslbf num_emission_tim 6 uimsbf num_xmtrs_in_group 6 uimsbf xmtr_group_num 7 uimsbf maj_log_override 3 bslbf num_miso_filt_codes 2 bslbf tx_carrier_offset 2 tcimsbf reserved 6 for (i=0; i<6; i++) ‘1’ } Bootstrap_Timing_Data () { for (i=0; i<=num_emission_tim; i++) seconds 32 uimsbf nanoseconds 32 uimsbf } } Per_Transmitter_Data () { Exciter Singaling ATSC 3.0 Exciter • • • Frame 3 Frame 2 Frame 1 Frame N ATSC S32-230r72 Revision o 9.3 Syntax and Semantics for L1-Detail D The syntax and field semantics of the L1 following subsections. The names of sign Table 9.8 L1-De Syntax L1_Detail_signaling() { L1D_version L1D_num_rf for (L1D_rf_id=1 .. L1D_num_rf) { L1D_bonded_bsid reserved } if (L1B_time_info_flag != 00) { L1D_time_sec L1D_time_msec if (L1B_time_info_flag != 01) { L1D_time_usec if (L1B_time_info_flag != 10) { L1D_time_nsec } } } for (i=0 .. L1B_num_subframes) { if (i > 0) { Maximum Network Delay (MND) (Point A: STLTP) network_delay_now network delay now = Device System Time() – Packet Release Time() where Device_System_Time() is the current time acquired by the remote device in synchronization with GPS or PTP. = Bootstrap_Timing_Data() – Packet_Release_Time()

(Point A: STLTP) packet_drop_count By checking whether the sequence number in RTP Header are continuous, with the missing packet number, we can quickly check whether the Packet Drop has been occurred. Cycle from 0 to 65535

(a) Dashboard #1: Real-time network topology monitoring Dashboard displaying data collected every second by a central server

(b) Dashboard #2: Graphs visualizing real-time data from multiple remote devices Dashboard displaying data collected every second by a central server (Point A) STLTP network_delay_now (Point A) STLTP packet_drop_count stl_fec_repair_count (Point B) RF x: rf_rssi, y: rf_mer (Point B) RF rf_status

20 Data Characteristics of ATSC 3.0 System Monitoring Metrics Anomaly type Meric Failure phenomenon (1) Mismatch stltp_ip stltp_port l1d_bsid l1d_version max_net_delay txid_seed txid_injection_lvl wakeup_bit stl_fec_state rf_frequency A matching issue between the BGW output multicast stream and the transmitter is occurring -> Not a normal transmission/reception situation (2) Event of interest packet_drop_count This is a situation in which data for RF signal generation cannot be normally received, and RF MUTE occurs when the amount of occurrence is high. stl_fec_repair_count The number of recovered packets does not affect actual broadcasting, but it can be confirmed that instability exists on the current transmission link. rf_fer This is the number of received error packets that remain even after all error corrections have passed. If a value other than 0 is observed, viewing inconveniences such as broken screens occur on the TV set.

21 Data Characteristics of ATSC 3.0 System Monitoring Metrics Anomaly type Meric Failure phenomenon (3) Concept drift network_delay_max network_delay_min This is an item representing the maximum or minimum value within the last 24 hours. It continues to be constant and then detects a change in value. In particular, whether the maximum value exceeds the MND is directly related to the occurrence of the SFN failure situation. (4) Point outlier stltp_bitrate In case of exceeding the maximum, Network Overflow -> a large amount of packet CRC errors -> RF MUTE occurs when packet drops exceed the allowable value If the minimum is not reached, If the BGW output is muted (or if the encoding of a specific channel is abnormal). rf_rssi The number of recovered packets does not affect actual broadcasting, but it can be confirmed that instability exists on the current transmission link. rf_mer This is the number of received error packets that remain even after all error corrections have passed. If a value other than 0 is observed, viewing inconveniences such as broken screens occur on the TV set.

Datetime -3σ -2σ -σ +3σ +2σ +σ μ Outlier -3σ +3σ μ Stltp_bitrate [Mbps] 30 29 25 STLTP output bit rate @ BGW AVG = 26.958 Mbps STD = 0.156 Mbps Capacity limit Anomaly Detection Framework for Time-Series Data based on 3-Sigma Rule The 3-sigma rule can be applied to detect anomaly situations that fall outside of 99.7% range. 1) stltp_bitrate:

Datetime network_delay_now Zero-mean standardization -3σ -2σ -σ +3σ +2σ +σ μ Outlier +3σ -3σ μ mean AVG = 16.458 ms STD = 0.670ms Anomaly Detection Framework for Time-Series Data based on 3-Sigma Rule The 3-sigma rule can be applied to detect anomaly situations that fall outside of 99.7% range. 2) network_delay_now: +6σ = 4.02ms -6σ

Coordinate Transformations Mahalanobis Distance rf_rssi rf_mer rf_rssi rf_mer Anomaly Detection Framework based on Mahalanobis Distance by combining two highly correlated metrics By transforming highly correlated time-series data (left) into a single plane (right) and applying Mahalanobis distance, various outlier points can be more clearly detected. A screen shot of a real-time monitoring system displaying data from Dashboard #2 (Case Study) Constant rf_rssi values, Decreasing rf_mer values

MER [dB] RSSI [dBm] 2022-05-29 00:00:00~09:16:30 KM Case Study: Constant rf_rssi values, Decreasing rf_mer values ATSC 3.0 TV #1 ATSC 3.0 TV #2

26 Conclusion: A straightforward proposal of a technique applicable to ATSC 3.0 operational data, along with its real-world validation. Theory Practice Standard

https://towardsdatascience.com/a-comprehensive-beginners-guide-to-the-diverse-field-of-anomaly-detection-8c818d153995 Further Studies: Deriving sophisticated techniques for detecting various anomaly conditions and conducting real-world validation. International Journal of Data Science and Analytics (2021) 12:297–331 https://doi.org/10.1007/s41060-021-00265-1