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1 Topic 8 Digital Audio Broadcasting and DMB

2 Contents of the 5 th week lecture Digital Audio Broadcasting DMB 2

3 Mobile TV

4 Mobile TV standards 4

5 Digital Audio Broadcasting and Digital Radio

6 DAB System

7 Why DAB? More power and spectrum efficiency High quality audio Multimedia radio Good for eliminating the effects of channel di stortions and fades 7

8 Digital Radio Broadcasting ITU Standard EUREKA-147 Hybrid IBOC(In-Band On-Channel) ISDB-TSB Frequency band 기존 FM (VHF; 30MHz~300MHz) 및 UHF (300MHz~3GHz)대역 사용 30MHz 이하 대역 사용 (DRM) vs. AM 방송 위성주파수 사용(DSB) 8

9 지상파 DAB 비교 BST: Band Segmented Transmission 9

10 위성 DAB 비교 10

11 EUREKA 147

12 EUREKA ; EUREKA 147 project 로 명명 EBU(European Broadcasting Union) 1994 ; ITU Digital System-A(ITU-R BS.1114, BO. 1130) 1997; ETS , adopted by ETSI(European Telecommunications Standard Institute) a complete DAB transmission system, and in particular contains refinements to the Eureka 147 DAB system with regard to establishing single frequency networks in the L-band (1.4 GHz). 12

13 EUREKA-147 Features The DAB transmission signal carries a multiplex of several digital services simultaneously within the overall bandwidth is MHz. The ensemble contains audio programs, data related to the audio program and optionally other data services. Usually, the receiver will decode several of these services in parallel. A specific part of the multiplex contains information on how the multiplex is actually configured, so that the receiver can decode the signal correctly. It may also carry information about the services themselves and the links between different services. Flexible audio bit-rate, from 8 kbit/s to 384 kbit/s, which allows the multiplex to be configured in such a way that it provides typically 5 to 6 high-quality stereo audio programs or up to 20 restricted-quality mono programs. Data services Program Associated Data(PAD) embedded in the audio bitstream Conditional Access Service Information (SI) 13

14 Generation of a DAB Signal 14

15 Reception of a DAB Signal 15

16 Audio Services MPEG-1 Layer 2, MPEG-2 Layer 2 The DAB Specification permits full use of the flexibility of Layer II except for the fact that only the standard studio sampling frequency of 48 khz and the half sampling frequency of 24 khz are used. Layer II is capable of processing mono, stereo and dual-channel such as bilingual programs. Different encoded bit-rate options are available (8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160 or 192 kbit/s per monophonic channel). In stereophonic or dual-channel mode, the encoder produces twice the bit-rate of a mono channel. 16

Data Services - PAD Each audio program contains Program Associated Data (PAD) with a variable capacity (minimum 667 bit/s, up to 65 kbit/s) which is used to convey information together with the sound

17 Data Services - PAD Each audio program contains Program Associated Data (PAD) with a variable capacity (minimum 667 bit/s, up to 65 kbit/s) which is used to convey information together with the sound program. The PAD Channel is incorporated at the end of the DAB/ISO audio frame. Typical examples of PAD applications are dynamic range control information, a dynamic label to display program titles or lyrics, speech/music indication and text with graphic features. 17

18 Data Services Independent Data Services In addition to PAD, general data may be transmitted as a separate service. Independent data Transmission ways 1) in the form of a continuous stream segmented into 24 ms logical frames with a data rate of n x 8 kbit/s (n x 32 kbit/s for some code rates) 2) in packet mode, where individual packet data services may have much lower capacities and are bundled in a packet sub-multiplex. 3) as a part of the FIC (Fast Information Channel). Typical examples of Independent Data Services Traffic Message Channel Correction data for Differential GPS Paging Electronic newspaper 18

19 Conditional Access Every service can be fitted with Conditional Access if desired. The Conditional Access (CA) system includes three main functions: Scrambling/descrambling - The scrambling/descrambling function makes the service incomprehensible to unauthorised users. Entitlement checking - Broadcasting conditions required to access a service, together with encrypted secret codes to enable descrambling for authorised receivers Entitlement management. - The entitlement management function distributes entitlements to receivers. 19

20 Service Information Information for program selection and for operation and control of receivers basic program-service label (i.e. the name of a program service) program-type label (e.g. news, sports, classical music) dynamic text label (e.g. the programme title, lyrics, names of artistes) program language time and date, for display or recorder control switching to traffic reports, news flashes or announcements on other services cross-reference to the same service being transmitted in another DAB ensemble or via AM or FM and to other services transmitter identification information (e.g. for geographical selection of information) Essential items of SI that are used for program selection are carried in the FIC. 20

21 Channel Coding and Time Interleaving The data representing each of the program services is subjected to energy dispersal scrambling convolutional coding time interleaving 21

Main Service Multiplex The encoded and interleaved data is fed to the Main Service Multiplexer (MUX) where every 24 ms the data is gathered in sequences.

22 Main Service Multiplex The encoded and interleaved data is fed to the Main Service Multiplexer (MUX) where every 24 ms the data is gathered in sequences. The combined bit-stream output from the multiplexer is known as the Main Service Channel (MSC) and has a gross capacity of 2.3 Mbit/s. Depending on the convolutional code rate, the net bit-rate ranges from approximately 0.6 to 1.8 Mbit/s, accommodated in a DAB signal with a MHz bandwidth. 22

23 Transmission Frame 23

24 Frame Organization 24

25 DAB Emission Block Diagram FIC Data Services Multiplex Multiplex Controller Control Data Service Information A u d i o Programme Services PAD 24/48 KHz PCM Audio Signal Conditional Access Scramble r General Data Services Conditional Access Scrambler Service Information Assembler ISO Layer I I Audio Encoder FIDC MCI Packet Multiplex Assembler Stream-mode Data Fast Information Block Assembler Packet Mode Packet SI Multiplex Assembler DAB Audio Frame Packet Mode Data SI AIC Conditional Access Scrambler Conditional Access Scrambler Conditional Access Scrambler Energy Dispersal Scrambler Energy Dispersal Scrambler Energy Dispersal Scrambler Energy Dispersal Scrambler Energy Dispersal Scrambler Convolutional Encoder Convolutional Encoder Convolutional Encoder Convolutional Encoder Convolutional Encoder Time Interleaver Time Interleaver Time Interleaver Time Interleaver CIF MSC FIC & MSC (frequency interleaved) Symbol Generator FIC Main Service Multiplexer Transmission Frame Multiplexer Synchronisation Channel Symbol Generator OFDM Signal Generator TII Signal Generator + DAB Transmission Signal 25

26 DAB Signal Structure (1) Frame 77 symbols, 3 channels 3 channels Main Service Channel(MSC) - used to carry audio and data service components(time-interleaved chan nel with EEP(Equal Error Protection) or UEP(Unequal Error Protection)) - The output signal from the main service multiplexer is contained in MSC - Stream Mode data are carried in logical frames transparently from source to destination. - Packet Mode data groups within a sub-channel. - made up of a sequence of common interleaved frames (CIF) - Each CIF contains 55,296 bits, which is equivalent to 864 capacity units (CU), which is the smallest addressable unit within the DAB signal - The main service channel contains 72 symbols of the total 77 symbol frame. 26

27 DAB Signal Structure (2) 3 channels (Cont d) Fast Information Channel(FIC) - used for rapid access of information by a receiver( non-time-interleaved channel with fixed EEP). - contains information about the configuration of the actual multiplex, the data service components, and any service information, if present. - It is made up of fast information blocks (FIB), each of which contains 256 bits of information about the configuration of the main service channel. - 3 symbols of the total 77 symbol frame. 27

28 DAB Signal Structure (3) 3 channels (Cont d) Synchronization Channel and Null Symbol - used to reference the time information in the fast information channel. - This information contains the time of transmission of the null symbol in the transmission frame carrying time information. - Also used for demodulation functions such as channel state estimation, automatic frequency control, and may contain transmitter identification information. 28

29 Multiplex Configuration Information (MCI) Basically describes how the DAB multiplex is organized. Providing the following information: defines the sub-channel organization; lists the services available in the ensemble; establishes links between services and services comp onents; establishes links between sub-channel and service co mponents; manages the multiplex re-configuration. 29

30 DAB Modulation (1) DQPSK COFDM to combat frequency selective fading, and multipath propagation distortions. It also can be used to establish single frequency networks Guard interval between successive symbols - channel selectivity and multipath propagation will not cause inter-symbol interference 30

31 OFDM Sub-channel Spectrum OFDM Spectrum data source serial-to -parallel signal mapper IFFT P/S guard interval inserti on D/A upconverter FFT Based OFDM System Channel data out downconverter parallelto-serial signal mapper FFT S/P guard interval removal A/D 31

32 DAB Modulation(2) 32

33 Guard Interval maintaining the orthogonality in the presence of echoes avoid ISI wasted power 33

34 DAB Transmission Modes 34

35 DAB Emission Block Diagram FIC Data Services Multiplex Multiplex Controller Control Data Service Information A u d i o Programme Services PAD 24/48 KHz PCM Audio Signal Conditional Access Scramble r General Data Services Conditional Access Scrambler Service Information Assembler ISO Layer I I Audio Encoder FIDC MCI Packet Multiplex Assembler Stream-mode Data Fast Information Block Assembler Packet Mode Packet SI Multiplex Assembler DAB Audio Frame Packet Mode Data SI AIC Conditional Access Scrambler Conditional Access Scrambler Conditional Access Scrambler Energy Dispersal Scrambler Energy Dispersal Scrambler Energy Dispersal Scrambler Energy Dispersal Scrambler Energy Dispersal Scrambler Convolutional Encoder Convolutional Encoder Convolutional Encoder Convolutional Encoder Convolutional Encoder Time Interleaver Time Interleaver Time Interleaver Time Interleaver CIF MSC FIC & MSC (frequency interleaved) Symbol Generator FIC Main Service Multiplexer Transmission Frame Multiplexer Synchronisation Channel Symbol Generator OFDM Signal Generator TII Signal Generator + DAB Transmission Signal 35

36 Terrestrial DAB Distribution Networks 36

37 IBOC DAB

38 IBOC In Band on Channel (IBOC) DAB In USA shares the same frequency bands as frequency modulated (FM) signals. In this hybrid system the DAB signal is placed on either side of the FM radio signal, from about 130 khz to 200 khz away from the host FM center frequency. The COFDM carriers are individually modulated using QPSK modulation and there are approximately 95 carriers in each sideband. 38

39 Digital Radio in the AM Bands

40 Digital Radio in the AM Bands DRM(Digital Radio Mondiale) US Digital Radio USA 40

41 Digital Radio Mondiale 41

42 Digital Multimedia Broadcasting

43 Portable and Mobile Digital Broadcasting

44 DTV 및 DMB 차이 (1) 44

45 DTV 및 DMB 차이 (2) 45

46 DTV 및 DMB 차이 (3) 46

47 휴대 이동 방송 서비스의 特徵 휴대 이동 방송은 신개념의 서비스로 세가지 특징을 지님 - 이동성 : 바로 여기서, 지금 당장 방송 시청이 가능한 매체 - 개인화 : 기존 가족 중심 TV 시청 개인 시청으로 변화 - 양방향화 : DMB 휴대폰을 통한 양방향 통신 서비스 이동성 개인화 언제 어디서나 시청이 가능한 서비스 (최대 150Km/h의 속도에서도 수신 가능) 내손안의 TV 나만의 방송 방송과 통신의 융합 양방향 서비스 상향 양방향 채널을 이용한 개별 프로그램화 47

883 GHz) 한별위성 144도 E Contents Ku-band (12.214~12.239 GHz) S-band (2.630~ 2.

48 위성 DMB 소형 자동차만한 위성 (36000km상공) 에서 방송 서비스 송신 - 방송 신호가 미약한 음영 지역은 중계기(Gap Filler)를 통한 재송신 전세계적으로 일본과 한국이 상용 서비스 중 Ku-band (13.824~ GHz) 한별위성 144도 E Contents Ku-band (12.214~ GHz) S-band (2.630~ GHz) Gap Filler S-band VOD Commerce Combined with mobile Internet Mobile phone 48 Vehicle-mounted Terminal Dedicated Terminal 48

49 위성주파수 대역 명칭 주파수(GHz) L-band 1.2 ~ 2.0 S-band 2.0 ~ 4.0 C-band 4.0 ~ 8.0 X-band 8.0 ~ 12.0 Ku-band 12.0 ~ 18.0 Ka-band 18.0 ~ 40.0 Milimeter 40 ~

50 지상파 DMB 방송 송신탑에서 공중파 방송 서비스 송신 지상파 DMB: 국내의 T-DMB와 해외기술인 DVB-H, MediaFLO VHF 채널 12, 8 번 할당, 각 채널당 3개 사업자, 1사업자당 비디오 1, 오디오 3, 데이터 1 개 제공 월, 한국 세계 최초 이동방송 (오디오 + 비디오) DMB 서비스 T-DMB 서비스 50

51 한국 T-DMB 구조 51

52 Extended Modes of DAB 52

53 DAB 와 한국 T-DMB 관계 53

54 한국 T-DMB Tx and Rx 54

55 한국 지상파 DMB 구성 EUREKA-147 DAB mode 1 사용 TV 채널당 (6MHz) 3개 사업자 VHF TV 8, 12 채널 사용 6개 사업자 ; KBS, MBC, SBS, YTN DMB, 한국 DMB, U1 미디어 6 MHz 구성 512 KHz-Block A-192 KHz-Block B -192 KHz Block C 496KHz Each Block ; MHz 1 개 블록(사업자) 비디오 1개, 오디오 3개, 데이터 2개 서비스 비디오 2개 서비스 55

56 지상파 DMB 서비스 타입 구분 오디오 서비스 멀티미디어 서비스 데이터 서비스 서비스 타입 CD Quality Stereo Audio 비디오 : VCD Quality (7 LCD) 오디오 : Above FM Quality(Max. CD) 데이터 : Text and Graphic PAD/NPAD : News, Wether, TPEG EPG, interactive services, etc. 56

57 지상파 DMB 기술 규격 57

58 DVB-H 특징 DVB-T에서 Mobile 용으로 진화 전력 소모를 절감할 수 있는 신기술(time-slicing) On demand service를 위한 필요한 주소 체계를 제공(IPv6) 양방향 서비스를 위한 규격 정의(UMTS, GPRS와 연동 가능) Broadcast + multimedia contents 방송과 통신의 융합 58

59 방송시스템 비교 요약(1) MediaFLO 위성 DMB 지상파 DMB DVB-H Modulation OFDM COFDM-QPSK COFDM-DQPSK Bandwidth Carrier Frequency Inter-activeness 전송속도, No. Channel Spectral efficiency (bits/hz) Playback delay (채널전환지연) MPEG 디코더 지연은 제외 6 MHz (5,7,8 MHz 가능) 700 MHz 대역에서 실험중, 실제론 UHF가 될 것으로 예상 비 표준 15 video, 7 audio (예상) COFDM- QPSK/16/64QAM 25 MHz 1.54MHz 5/6/8 MHz 2.6 GHz 2G/3G망 접속가능 (사업자 구현이슈) 7.5 Mbps (실제 서비스기준) 11 video, 25 Audio, 3 data UHF (VHF가능) 2G/3G망 접속가능 (사업자 구현이슈) 1 Video, 3 Audio, 2 data 1.0~ ~ ~ 1.1 VHF UMTS망 접속 표준화(CBMS) 진행 중 미정 0.6 ~ 2.5 (64 QAM ~ 4.17 가능 ) 1.5s(미확인사항) 3.5 s 0.5 s 4 s 내외 예상 59

60 방송시스템 비교요약(2) MediaFLO 위성 DMB 지상파 DMB DVB-H Authentication AAA (UIM-Unicast) CAS/Smart card CAS 표준 제정 중 CAS 표준 제정 중 Maximum Resolution QVGA 예상 QVGA CIF (QVGA도 지원) 미정 (QVGA 유력) Video Codec Enhanced H.264 (30 frame/s) H.264 (15 frame/s) H.264 (15or30 frame/s) H.264 유력 Audio Codec MPEG 4 AAC+ MPEG4 AAC+ MPEG4 BSAC MPEG 4 AAC+ 유력 중계방식 지상 송신+ 중계기 위성직접수신 + Gap filler 지상 송신 + 중계기 지상 송신 + 중계기 요금방식 미정 정액제 무료 (광고수익) 유료 (유럽) 주요제조사 Qualcomm 도시바, 삼성 프론티어실리콘, 삼성 노키아, 필립스 60

61 위성 및 지상파 DMB 比較 지상파 DMB 위성 DMB Frequency-band VHF(174 ~216MHz) S-Band(2.6GHz) Bandwidth 6MHz (1.536 MHz *3 multiplex) 25 MHz Transmission Method Eureka-147 (OFDM) System E (CDM) Modulation/Coding DQPSK/RS + Conv. Code QPSK/ RS + Conv. Code Audio Codec MPEG Audio Layer Ⅱ, MPEG-4 BSAC(Bit-Sliced Arithmetic Coding) Video Codec H.264 MPEG-4 Part 10 AVC MPEG-2 AAC+ SBR(Spectral Band Replication) H.264 MPEG-4 Part 10 AVC Service Channel 4~5 (contain Video channel) per multiplexer 30 ~40 channel 61

62 지상파시스템- DVB-H vs. T-DMB (1/2) bandwidth DVB-H 6MHz (규격상 5,6,7,8MHz가능) 지상파DMB 1.536MHz(하나의 앙상블) *3 ~ 전체 대역폭(6MHz) Sub-carrier 2k,4k,8k 1,536 가장 적합한 화면 크기 360*288 최대 352*288 채널 data rate(비디오) 384kbps 384kbps -526kbps(가변) Inner code rate 1/2-7/8 (convolution) 1/2 8/9 (convolution) Data rate Mbps ~ 11Mbps (BW= 8MHz일 때) 약 3Mbps (500kbps *6개) 전송방식 COFDM COFDM Video codec MPEG-4 H.264 MPEG-4 H.264 Audio codec MPEG4 AAC MPEG-4 BSAC 변조방식 QPSK, 16QAM, 64QAM DQPSK 부가 서비스 적용 (데이터 방송) 데이터 방송 고려 데이터 방송에 대한 표준화 진행 중 62

63 지상파시스템- DVB-H vs. T-DMB (2/2) DVB-H 지상파DMB 비고 송출 방식 하나의 송출 회사가 필요 앙상블마다 방송사를 지정 각각 송출 가능 Coverage 속도가 높을 경우 낮음 넓음 전력 소모 (front-end단 기준) 하드웨어 복잡도 (T-DMB=1) 주파수 효율 (T-DMB=1) 화면 전환 시 지연 요인 <100mW (Time Slicing 채용) 2배 이상 2.5배 정도 Time Slice 동기 IP streaming을 사용 <100mW 1배 1배 앙상블 변환 시 동기화 시간에서 delay 발생 DVB-H: 송출사와 방송사 분리 T-DMB: DVB대비 4배로 SFN구성에 다소 유리 DVB-H: Time slicing으로 90%이상 전력 소모 감소 (이론상) 많은 slice를 사용시: bit rate 감소 화질 저하 우려 버퍼링 시간 증가 지연 발생 가능 DVB-H: IP헤더로 인한 유효데이터 감소 T-DMB: 앙상블간 Guard band (총 6MHz중 4.5MHz)로 인한 효율저하 DVB-H: 버퍼링으로 인한 지연 T-DMB: 앙상블 변환 시 동기화 시간에서 delay 발생 63

64 휴대 이동 방송 국가별 표준 동향 위성 DMB: 지역별 독자표준 지상파 DMB : DAB방식과 지역별 표준 경쟁 구도 DVB-H 와 경쟁 유 럽 DVB-H DAB(T-DMB) 중 국 DAB, DVB-H DMB-H (자체표준) 미 국 DAB, DVB-H MediaFLO ATSC-M/H, IBOC 한 국 T-DMB 위성 DMB (System E) 일 본 ISDB-T 위성 DMB (System E) * IBOC : In Band On Channel (미국 오디오 방송 표준) * ISDB : Integrated Service Digital Broadcasting (일본 독자 지상파 DMB 표준)

Contents Why DMB? When DMB? Where DMB? What DMB? Who DMB? How DMB? Demonstration Conclusion 2/ 27

DMB Home Coming Day www.pixtree.com 1/ 27 Contents Why DMB? When DMB? Where DMB? What DMB? Who DMB? How DMB? Demonstration Conclusion 2/ 27 Why DMB? Digital Convergence 3/ 27 Why DMB? Anytime, Anywhere,