Hierarchical Modulation for DVB-T Implementation & Application Bernhard Baumgartner Senior Product Manager

Transcription

1 Hierarchical Modulation for DVB-T mplementation & Application Bernhard Baumgartner Senior Product Manager Hierarchical Modulation 1

2 Hierarchical Modulation for DVB-T Hierarchical Modulation is nothing new it is part of the DVB-T standard for several years. But The receiver industry did not always consider it exactly. Planners seldom check if hierarchical modulation adds additional value to their DVB-T network application Target of this presentation is to explain the theory of hierarchical modulation for DVB and to provide examples for possible implementations Hierarchical Modulation 2

3 What is hierarchical Modulation? Hierarchical Modulation allows to transmit two digital data streams via one transmitter the LP Stream (Low Priority) higher bit rate sensitive (higher C/N needed) the HP Stream (High Priority) lower bit rate Very robust (less C/N needed) Hierarchical Modulation 3

4 Sub Carrier Modulation non-hierarchical modes PSK 16-AM 64-AM PSK: 4 carrier positions A PSK carrier can transport 2 bits 16-AM: 16 carrier positions A 16-AM carrier can transport 4 bits 64-AM: 64 carrier positions A 64-AM carrier can transport 6 bits Hierarchical Modulation 5

5 Hierarchical Modulation PSK in 16-AM High priority bit stream (HP) defines actual quadrant Low priority bit stream (LP) defines position in actual quadrant Hierarchical Modulation 7

6 Hierarchical Modulation PSK in 64-AM High priority bit stream (HP) defines actual quadrant Low priority bit stream (LP) defines position in actual quadrant Hierarchical Modulation 8

7 α- Factor, C/N PSK in uniform 16-AM 3 α = 1: HP: PSK, CR 2/3, Req. C/N ~8.2 db ~ 7.5 Mbps LP: PSK, CR 2/3, Req. C/N ~ 11.1 db ~ 7.5 Mbps 3 Required C/N values are for EF reception after RS decoder! Hierarchical Modulation 10

8 α- Factor, C/N PSK in non-uniform 16-AM α = 4: HP: PSK, CR 2/3, Req. C/N ~5.9dB ~ 7.5 Mbps LP: PSK, CR 2/3, Req. C/N ~ 19.1 db ~ 7.5 Mbps 4 6 Required C/N values are for EF reception after RS decoder! Hierarchical Modulation 12

9 Coverrage Area of DVB-T Transmitters Field strength 64 AM Code rate 7/8 ~ 30 Mbit /s 16 AM Code rate 3/4 ~ 15 Mbit/s The area covered by a DVB-T transmitter is strongly depending on the selected parameters for the COFDM signal C/N PSK Code rate 1/2 ~ 5 Mbit/s C/N C/N noise floor Distance in km Hierarchical Modulation 15

10 Possible applications for hierarchical modulation transmit services to portable and fixed receivers at the same time increase net bit rate of the broadcast channel transmit services to stationary and mobile receivers at the same time transmit HDTV and SDTV at the same time with different coverage areas Hierarchical Modulation 16

11 Stationary vs Portable receivers LP Non- Hierarchical HP Non-hierarchical: 64 AM, G 1/8, FEC 2/3 Bit rate: Mbps C/N (Gaussian): 16.5 db HP: PSK, G 1/8, FEC 1/2 Bit rate: 5.53 Mbps C/N (Gaussian): 8.9 db LP: 16-AM, G 1/8, FEC 2/3 Bit rate: Mbps C/N (Gaussian): 16.9 db Hierarchical Modulation 17

12 ncreased useful bit rate LP Non- Hierarchical HP Mbps Non-hierarchical: 64 AM, G 1/8, FEC 2/3 Bit rate: Mbps C/N (Gaussian): 16.5 db HP: PSK, G 1/8, FEC 3/4 Bit rate: 8.29 Mbps C/N (Gaussian): 13.7 db LP: 16-AM, G 1/8, FEC 3/4 Bit rate: Mbps C/N (Gaussian): 18.6 db Hierarchical Modulation 18

13 Mobile & Stationary reception RF1 Non- Hierarchical RF1 LP RF 2 Non- Hierarchical RF 1 HP Non-hierarchical RF1: 64 AM, G 1/8, FEC 2/3 = Mbps Non-hierarchical RF2: PSK, G 1/8, FEC 2/3 = 7.37 Mbps HP - RF1: PSK, G 1/8, FEC 1/2 = 5.53 Mbps LP - RF1: 16-AM, G 1/8, FEC 3/4 = 16.59Mbps Hierarchical Modulation 19

14 Simulcast HDTV & SDTV Non- Hierarchical (HDTV) LP (HDTV) HP (SDTV) Non-hierarchical: 64 AM, G 1/8, FEC 2/3 Bit rate: Mbps C/N (Gaussian): 16.5 db HP: PSK, G 1/16, FEC 3/4 Bit rate: 5.53 Mbps C/N (Gaussian): 10.8 db LP: 16-AM, G 1/16, FEC 3/4 Bit rate: Mbps C/N (Gaussian): 21 db Hierarchical Modulation 20

15 Hierarchical Modulation in SFN Operation Audio/Video Encoder Audio/Video Encoder Transport Stream Multiplexer LP LP Telecom Network (Microwave, Fibre optics) Modulator Amplifier Audio/Video Encoder Audio/Video Encoder Transport Stream Multiplexer HP HP SFN Adapter Telecom Network (Microwave, Fibre optics) Modulator Amplifier Modulator Amplifier Only Requirement: Correct maximum network delay entered in SFN adapter Hierarchical Modulation 25

16 Synchrony SFN Adapter 1U rackable frame nput redundancy management Automatic bit rate adaptation process Mandatory and optional MP management NT update feature Embedded SNMP agent nternal PRBS generators for test purpose Time Stamp generation for Hierarchical Modulation integrated as a standard feature! Hierarchical Modulation 26

17 Atlas - DTV660 Product Line Air Liquid Hierarchical Modulation 27 Hierarchical Modulation s available as a standard option for all Harris DVB-T Transmitters

18 Summary Hierarchical modulation allows the Transmission of two independent AS data streams with different characteristic via one transmitter Transmission to stationary and mobile receivers on the same channel. Broadcasting of SDTV and HDTV on the same channel The required technology is now available as a standard transmitter option Hierarchical Modulation adds a lot of advantages and flexibility... to make Hierarchical Modulation a long term success DVB-T equipment manufacturers and broadcasters have to work together! Hierarchical Modulation 28

19 Herzlichen Dank für hre Aufmerksamkeit! Hierarchical Modulation 29