TV White Space Opportunities and Challenges Mark Waddell, Lead R&D Engineer 22 nd January 2013 Research & Development
Contents TVWS Opportunities Why it is important and interesting to Broadcasters Managing DTT protection Constructing the Geolocation Database Analysis of Availability Channels per household and regional variations Research & Development 2
Contents Emerging Challenges Receiver Performance (C/I issues) Evolving nature of WSD technology immature and potentially disruptive Choice of database parameters Research & Development 3
Why are White Spaces Important? Research & Development 4 4
Broadband is key to many new BBC Services Research & Development 5
Why is TV White Space Attractive? NOTHING HIGH SPEED INTERNET TVWS Research & Development 6
We need to protect. 50 TV channels 24 radio channels HD and PVR services Research & Development 7
Why is protecting DTT so important? Research & Development 8
UK TV Consumption by Platform Q1 2011 19 million households using Terrestrial TV Platform 10.1 million for primary set 0.3 million adding pay TV DTT services 1.8 million on Analogue Terrestrial Expected to adopt DTT when UK DSO completes in 2012 Research & Development 9
Striking a Balance. Protecting Free to Air DTT Services Enabling WSD applications: Broadband Networks M2M Networks Balance controlled by the choice of Database parameters Research & Development 10
DTT Protection using a Geolocation Database Construct a Database from UK DTT Coverage Data Split Country into 100x100m pixels Protect only the preferred DTT channels Allow an acceptable loss of coverage Protect only populated pixels Calculate WSD EIRP limit for given interference budget Visualise results Maps: Illustrate regional variations Graphs: Household availabilty vs WSD power Postcode checker Research & Development 11
Constructing the Database DTT Planning Data Coverage Predictions Protected Transmitters Permitted Coverage Loss Maximum Permitted Co channel Interference Field at the DTT Antenna DTT Rx Selectivity (PR) WSD DTT coupling Separation distance Propagation Model WSD ERP restrictions Max ERP that will not degrade coverage at any DTT receiver in neighbouring pixels Research & Development 12
Combining Roof Top and Set Top restrictions Roof Top Restrictions Set Top Restrictions Combination For each Pixel Channel the minimum of the two Research & Development 13
Channel Availability @ WSD ERP = 30 dbm Roof Top Only Combined 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Research & Development 14
Spectrum Availability per Household Roof Top Only Combined Research & Development 15
WSD Geolocation Database Demonstrator Research & Development 16 16
WSD Geolocation Database Demonstrator Research & Development 17 17
Understanding Spectrum Availability TVWS Spectrum is Fragmented Channel availability varies with location Channel availability is power dependent Fewer channels at high power Variations can be shown on maps Quality of spectrum varies Must consider effects of unwanted TV coverage and interference on WSD performance Research & Development 18
Availability Cambridge for 30dBm (Roof Top Protection) 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Research & Development 19
Availability Cambridge for 30dBm (Combined Protection) 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Research & Development 20
Availability Glasgow for 30dBm (Roof Top Protection) 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Research & Development 21
Availability Glasgow for 30dBm (Combined Protection) 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Research & Development 22
Availability London for 30dBm (Roof Top Protection) 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Research & Development 23
Availability London for 30dBm (Combined Protection) 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Research & Development 24
Channel Availability at -30dBm 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Research & Development 25
Channel Availability at 0dBm 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Research & Development 26
Channel Availability at 30dBm 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Research & Development 27
Emerging Challenges Receiver performance BBC has been working to understand real receiver performance Selectivity (ACS) determines required protection ratio (C/I) Tests have revealed significant issues Receiver AGC design degrades effective ACS, increasing required protection ratios Trend towards Silicon tuners is resulting in reduced performance Research & Development 28
BBC Receiver Study How will receivers coexist with the new WSD Technology? WSD Research & Development 29 29
Introduction to Protection Ratios Protection Ratios Fundamental to Database construction Defines maximum WSD Interference for onset of picture failure PR Research & Development 30 30
BBC Methodology for C/I testing 14 Current Receiver Designs Tested 7 Silicon Tuners, 7 CAN Tuners 6 IDTVS, 6 STBs, 2 PVRs 5 Candidate WSD Technologies considered (LTE, WiMAX, WiFi, WSD1, WSD2) Real CPE and BS signals captured on an RF recorder 3 traffic levels (generated by iperf) 30 test signals in total ATE developed to automate measurements WSD recordings replayed on a lab signal generator Research & Development 31 31
C/I Characteristic Good Receiver (1 st Adjacent) Research & Development 32 32
C/I Characteristic Poor Receiver (1 st Adjacent) Research & Development 33 33
WiMAX CPE Idle All Receivers (1 st Adjacent) Research & Development 34 34
WiMAX CPE Idle All Receivers (3 rd Adjacent) Research & Development 35 35
Summary of Results All WSD waveforms Research & Development 36 36
Performance Degradation Mechanisms WSD/ TDD Original DVB-T Signal TDD Modulated DVB-T Time Time Time WSD signal overloads DTT tuner until AGC can operate AGC modulated by WSD TDD signal and TDD envelope wiped onto DTT signal Research & Development 37
Impact on TVWS Availability Research & Development 38
TVWS Availability Ofcom reference PRs Research & Development 39
TVWS Availability WiMAX PRs (80% receivers) Research & Development 40
Conclusions TVWS presents exciting opportunities. Connect rural areas and fix broadband not-spots Improve WiFi experience in homes and businesses Multimedia streaming and 2 nd screen support Provide harmonised spectrum supporting low cost devices But there are challenges. Significant regional variations Permitted power, number of channels Quality of spectrum Must make best use of the limited resource Need efficient radio system Must protect our DTT platform used in 80% of homes Research & Development 41
Conclusions Receiver performance a potential issue Degraded C/I characteristic is reducing TVWS availability Opportunities to improve tuner designs Opportunities to develop better WSD technologies Less interfering Higher performance Indoor applications (Small Cell) Research & Development 42
Thank you for your attention Research & Development 43