HistoryHistory andand TechnologyTechnology ofof IISDBSDB--TT ~~ aimingaiming atat mobilemobile andand portableportable receptionreception ~~ 17, September, 2007 Argentina DiBEG, JAPAN Osamu Yamada Pioneer Digital Broadcasting Expert Group 1 BiographyBiography 1944 Born in Tokyo 1967 Graduated from Waseda University and joined NHK 1971 Started research of new broadcasting systems 1975-1985 Engaged in the development of Teletext 1985-1992 Engaged in the development of FM multiplex broadcasting 1986-2002 Engaged in the development of terrestrial digital broadcasting 1991-2000 Engaged in the development of satellite digital broadcasting 1999-2002 Director General of NHK Science and Technical Research Laboratories 2002 left NHK and Joined Pioneer 2005 Senior Managing Director of Pioneer 2007 Executive Corporate Adviser, R&D 2 ContentsContents 1. History 2. TELETEXT 3. FM Multiplex Broadcasting 4. ISDB-T 4.1 OFDM 4.2 Frequency Assignment 4.3 Mobile Reception 4.4 Effective Usage of Frequency 4.5 System Parameter and BST-OFDM 4.6 Receivers 4.7 New Technologies for Receivers 4.8 New Technologies for SFN 4.9 International Activities 5. Conclusion 3 1.1. BroadcastingBroadcasting HistoryHistory inin JapanJapan 4 HistoryHistory ofof BroadcastingBroadcasting TechnologyTechnology inin JapanJapan 05 03 ISDB-T Digital(7years) 2000 00 ISDB-S 95 94 FM Multiplex Broadcasting 90 91 Experimental BS HDTV 85 TELETEXT Work for NHK 85 84 Experimental Analog BS (35years) 80 82 TV with Multi-ch Audio 75 TV(47years) 70 70 FM Radio 65 60 60 NTSC Color TV 55 53 TV 50 45 40 Radio(28years) 35 30 30 NHK STRL 1925 25 AM Radio 5 ResearchResearch HistoryHistory 1975～1985 TELETEX 1985～1994 FM Multiplex Broadcasting 1992～2000 ISDB-S 1986～2002 ISDB-T 6 2.2. TELETEXTTELETEXT （（19751975～～19851985）） 7 TELETEXTTELETEXT (1) TELETEX is the first service with digital technology in analog broadcasting age. (2) Characters and graphics are coded and multiplexed with the vertical blanking period of analog TV signals. (3) In 1970s, three systems, System A (France), System B (UK), System C (North America), and System D (Japan) had been developed. (4) At present, System B, and System D are available. (5) Japanese each character has a different meaning. Bit errors give erroneous information, therefore bit error can’t be permitted. (6) Only Japanese TELETEXT system had been making much of the development of error correcting codes. (7) Japanese TELETEXT never shows incorrect characters, because of the new error correcting method we developed. 8 FieldField TrialTrialｓｓ ofof TELETEXTTELETEXT Ｆｉｅｌｄ Ｔｒｉａｌ ｉｎ Ｗａｋａｙａma Error Pattern Analizer 9 ResearchResearch ResultResult (1) The simulation results using error patterns collected in the actual field trials showed that the (272,190) code was the best. (2) The (272,190) code is one of the majority logic decodable codes, and it is called a difference Set Cyclic Code. (3) The (272,190) code is one of LDPCs (Low Density Parity Check), which are hot topics in an error correcting code field. 10 PacketPacket SignalsSignals ofof TELETEXTTELETEXT 11 EErrorrror CorrectingCorrecting CapabilityCapability ofof thethe (272,190)(272,190) CodeCode 10 -1 10 -2 10 -3 No coding ate r -4 o 10 rr e - -5 t 10 (272,190) code Bi Convolutional code 10 -6 (272,190) (Viterbi hard 1/2) 10 -7 Product code 0 2 4 6 8 10 12 Eb/No (dB) 12 ErrorError CorrectingCorrecting CapabilityCapability ofof thethe (272,190)(272,190) CodeCode 10-6 A : Error correction B : Error detection 10-8 -10 10 A B 10-12 10-14 -16 Bit Error Rate 10 10-18 after Error Correction or Detection 10-20 10-22 10-4 10-3 10-2 Bit Error Rate of Received Signals 13 EffectEffect ofof thethe (272,190)(272,190) CodeCode Ghost interference Random noise (Delay time:2.5μs,D/U=7dB, (Input level:31dBμV, Bit-error-rate:4.03x10-3) Bit-error-rate:2.4x10-2) 14 ApplicationsApplications ofof thethe (272,190)(272,190) CodeCode (1) TELETEXT : (272,190) (2) FM multiplex Broadcasting : Product Code- (272,190)X(272,190) (3) Optical Card System for immigration card in U.S.A : Product Code-(272,190)X(272,190) (4) Protection for key of BS Pay TV : (272,190) (5) ISDB-T : Shortened (184,102) for TMCC signals 15 WhatWhat wewe werewere taughttaught (1) Digital signals are robust against random noise, but very weak against wave distortion. (2) Error correction is one of the key technologies in digital broadcasting, and indispensable technology for digital transmission. (3) Thanks to the progress of LSI, theoretically difficult themes can be realized. (4) Though analog TV can be received in running cars to some extent, TELETXE signals(5.27Mbps) can’t be received. (5) At that time, I believed that digital terrestrial TV broadcasting would be impossible, because of high bit rate of video signals and difficulty of mobile reception. 16 3.3. FMFM MultiplexMultiplex BroadcastingBroadcasting ーーDARC(DataDARC(Data RadioRadio Channel)Channel)ーー (1986(1986～～1995)1995) 17 FFrequencyrequency SpectrumSpectrum ofof FMFM StereoStereo BroadcastingBroadcasting SignalsSignals 0 0 Pilot -20 L+R L-R -20 -40 -40 Multiplexable Level (dB) Level (dB) band -60 -60 0 20 40 60 80 100 0 20 40 60 80 100 Baseband frequency (kHz) Baseband frequency (kHz) Original baseband spectrum and multiplexable Baseband spectrum of FM stereo band of FM stereo broadcasting broadcasting under multipath interference 18 FrequencyFrequency SpectrumSpectrum ofof DARCDARC 0 Pilot tone -20 L+R L-R DARC -40 Relative level (dB) -60 0 20 40 60 80 100 Baseband frequency (kHz) 19 Error Correction of DARC Powerful error correction by (272,190) product code Data Parity Parity Parity Product code 20 CarCar NavigationNavigation SystemSystem withwith VICSVICS (Vehicle Information Communication System) Penetration in March, 2006 1.5 Million 21 ExampleExample ofof VICSVICS Yellow ： traffic jam Red ： heavy traffic jam 22 PerformancePerformance ofof thethe (272,190)(272,190) productproduct codecode 10 -1 10 -2 10 -3 No coding 10 -4 10 -5 (272,190) code Bit-error rate Convolutional code 10 -6 (272,190) (Viterbi hard 1/2) 10 -7 Product code 0 2 4 6 8 10 12 Eb/No (dB) 23 ComparisonComparison ofof DARCDARC andand RDSRDS System DARC RDS Subcarrier 76 kHz 57 kHz Multiplex level 4～10％ 2～3％ Modulation LMSK BPSK Bitrate 16 kbit/s 1.2 kbit/s (272,190) Error correction (26,16) code product code 24 WhatWhat wewe werewere taughttaught (1) Many kind of digital modulation methods (2) Difficulty of mobile reception : poor antenna gain, fading interference, ghost interference (3) For example, the difference of antenna gain between fixed reception and mobile reception is more than 15 dB. (4) Existence of potential need, so called traffic information service 25 ４４.. ISDBISDB--TT (1986(1986--2002)2002) 26 MeritsMerits ofof DigitalDigital BroadcastingBroadcasting (1) Robustness against noise (2) Easy channel assignment (3) Effective use of bandwidth (4) Mobil and portable reception (5) High video quality (6) Affinity to computer and Internet (7) Easy to add new services (8) Fit for LSI technology 27 IntroductionIntroduction ofof DigitalDigital BroadcastingBroadcasting Year 94 96 98 2000 02 04 06 08 Japan ISDB-S BS ▽ Satellite ▽ ▽ 12GHz Band CS 110 degree CS Terrestrial Analog Broadcasting will be closed in 2011 TV ISDB-T Start broadcasting in 3 metropolitan areas ▽ Audio ISDB-Tsb Test broadcasting in Tokyo, Osaka▽ Cable ISDB-C ▽ US Satellite ▽DirecTV, USSB etc. Terrestrial ▽ DTV ▽ End of Analog Broadcasting Europe Satellite ▽ Canal Sat. etc.(France, Italy, Germany, Spain etc.) Terrestrial UK (BBC) etc. ▽ 28 Implementation Schedule of ISDB-T in Japan Jul. 2011 Analog disappears Oct. 2006 Start of ISDB-T (main city of the whole country) Apr 1.st 2006 Start of 1-Segment Broadcasting Dec 1.st 2003 Start of ISDB-T (Tokyo, Nagoya, Osaka) Apr. 2003 Provisional licenses were awarded Feb.2003 Start of Analog channel relocation 1999-2003 Real Scale Experiment Broadcasting 1999 MPT established technical standard 1998 Issue of Digital Broadcasting Study Group Report 1994 MPT asked to Council for technical requirement 29 SystemSystem RequirementsRequirements andand PrincipalPrincipal TechnologiesTechnologies (1) Excellent transmission characteristics OFDM (2) HDTV, mobile and portable services OFDM, time interleave, hierarchical transmission and one seg (3) System flexibility Segment structure (4) Effective use of frequency SFN 30 WhyWhy MobileMobile andand PortablePortable ReceptionReception (1) All kind of TV programs including data services can be received at home in the future, via satellite, cable, internet, etc.. (2) People’s outside life times are increasing in the present-day life. (3) Broadcasters have to anytime serve information including video, audio, and data. (4) Especially, the emergency information service is related to a matter of life and death, therefore it is a very important role for broadcasters to provide people with emergency information anytime and anywhere. (5) Above media in (1), can’t provide people such services, and VHF and UHF band frequency used by broadcasters, are the best for mobile and portable reception. (6) In the age of the convergence of broadcasting and communication, Broadcasters can’t survive without mobile and portable services. 31 4.14.1 OFDMOFDM （（OrthogonalOrthogonal FrequencyFrequency DivisionDivision Multiplex)Multiplex) 32 DABDAB (Digital(Digital AudioAudio BroadcastingBroadcasting)) (1) In 1980’s, EBU developed Digital Audio Broadcasting (DAB). (2) DAB adopted two new digital technologies, OFDM (Orthogonal Frequency Division Multiplex, CCETT in France) and digital audio compression