Multimedia Communications Multimedia Technologies & Applications. Prof. Dr. Abdulmotaleb El Saddik

Transcription

1 Multimedia Communications Multimedia Technologies & Applications Prof. Dr. Abdulmotaleb El Saddik Multimedia Communications Research Laboratory School of Information Technology and Engineering University of Ottawa Ottawa, Ontario, Canada 1 site.uottawa.ca mcrlab.uottawa.ca Satellite Technologies and Multimedia Services 1

2 Satellite Multimedia Services Internet Intranet MAN 3 End user PC Multimedia Applications over Satellite Video, Audio, and Data services TV broadcasting (digital TV, HDTV, MAC- European system) DAB (digital audio broadcasting) News distribution Video on demand, audio on demand Home shopping Entertainment Distance education Others 4 2

3 Land-Satellite Network Configurations CPE-CPE: Customer Premise (or Provided) Equipment A wide range of customer-premises terminating equipment which is connected to the local telecommunications network: telephones, modems, terminals, routers, set-top boxes, etc. LAN Interconnection Public MANs Public Networks 5 CPE-CPE Interconnection CPE CPE Gateway Gateway Database 6 Switch Switch 3

4 LAN Interconnection GATEWAY GATEWAY 7 Public MAN-CPE Interconnection CPE GATEWAY Gateway 8 PUBLIC MAN Switch 4

5 Public Network-CPE CPE GATEWAY Gateway PUBLIC Network Switch 9 Direct Broadcast Satellite (DBS) Radio communication service in which Signals Audio, Video & Data/Text are transmitted via Satellite for direct reception by the consumer. Single point to Multipoint Link. 10 5

6 11 The Advantages of DBS Economical long distance signal transmission Wideband capacity Typically 24MHz of bandwidth is available in each transponder Global coverage About 42% of the earth surface is within view of a geostationary satellite Better coverage of rural and undeveloped areas. Superior quality reception with digital Video & Audio. Highly User friendly with Interactive Remote control. Basic elements in a DBS system Earth Station {uplink} for processing program material & uplinking to the Satellites. Satellites operating transponders in Ku (DBS) band receive signals on the uplink carrier down convert, amplify and beam them back to earth. Receiving system comprises of a 24 parabolic antenna with with smart card access and a TV/ PC. Frequency Band Downlink Uplink; C ,200 MHz 5,925-6,425 MHz Ku GHZ GHz 12 Ka GHz GHz 6

7 The Signal Transmission Path in DBS Forward path uplink (earth station to satellite) in DBS, only a single carrier exists in the transponder. Therefore, all the programs are assembled and multiplexed at the same geographical position. downlink (satellite to public receiver) Return Path (optional for interactive services) telephone line, internet 13 ORBITAL SLOT ALLOCATIONS 175 west 166 WEST 157 WEST 148 WEST EARTH WEST 110 WEST 101 WEST 61.5 WEST 7

8 TRANSPONDER PARAMETERS DBS Frequency 17.3 to 17.8 GHz No of Transponders Channel Bandwidth 24 MHz per Transponder Polarization RHCP /LHCP Transponder Power High power 240 W Low power 120 W Propagation factors of Satellite Signals free space losses attenuation due to cloud, rain and snow atmospheric effect Faraday rotation effect (signal attenuation) signal losses due to scintillation (signal fading) Adjacent channel interference (from the different transponders) interference from terrestrial transmission 16 8

9 DBS receiving system VIDEO AUDIO TEXT/DATA LNB DECODERS & OUTPUT BUFFERS RAM Demodulation, Synchronization Recovery & FEC DESCRAMBLER, DEMULTIPLEXER PACKER FILTER RAM 17 Card reader CONTROL mp Source coding and multiplexing MPEG-2: in order to operate the TWTA close to saturation, thus optimizing the satellite power efficiency, TDM should be employed. Program Video Transport Audio mux 1 Data 2 mux n MUX Adaptation & Energy Dispersal Outer Coder RS(204,188) Interleaver (I=12) Convolution Inner Coder To the RF Satellite Channel Baseband Shaping QPSK Modulator 18 MPEG-2 Source coding & Multiplexing Satellite Channel Adapter 9

10 19 Channel coding and modulation channel coding Reed-Solomon (RS) code for Forward Error Correction (FEC) Viterbi convolutional code for outer error correction: the convolution code can be flexibly configured to operate at different rate:1/2, 1/3, 3/4, 5/6, 7/8, allowing the optimization of the system performance for the satellite transponder bandwidth and power. modulation QPSK is suggested by the fact that DTH services via satellite are particularly affected by power limitations rather than by bandwidth constraints. e.g., at a symbol rate of 20 Msymbols/sand 2 bits / symbol with FEC of 3/4 Convolutional code and 188/204 RS we have a net Info Rate of 40 x 3/4 x 188/204 = 27 Mbps. DirecTV Introduced in June 1994 in U.S.A. Programming is distributed by DirecTV, a unit of Hughes Electronics Corporation and United States Satellite Broadcasting Company, Inc. (USSB) 3 high-power HS601 satellites (DBS -1, DBS-2, DBS -3) are co-located in geostationary orbit 22,300 miles above the earth at 101 degree west longitude Each satellite features watts Ku band transponders DBS-1 delivers up to 60 channels of DirecTV programming and approximately 20 channels of programming from USSB DBS-2 and DBS-3: provide 8 transponders at 240 watts 20 10

11 DirecTV (cont d) Capacity: up to 175 channels of digital programs 18 inch dish MPEG -2 compatible bandwidth: 24 MHz/transponder SmartCard for conditional access. SmartCard is a creditcard sized processor board which plugs into the front of the decoder to allow the decoder to receive the authorized programming. 21 ExpressVu-Canada s first National digital television services up to 100 channels Antenna size 60cm (24 inch) using Canadian Telesat Anik E1 satellite, in a geostationary orbit approximately 23,500 miles above the equator at longitude 111 degrees (directly south of Winnipeg). coast-to-coast coverage from Vancouver, BC to St. John, NF, up to Yukon and Northwest Territories. All levels of audio: mono, stereo, and including surround sound stereo are supported, if the source program carries these features

12 DirecPC DirecPC, introduced in November 1994, is a high performance satellite data distribution services from Hughes Network Systems (HNS). DirecPC can give you rapid access to information from a variety of sources via a small easy-to-install satellite dish. Using Galaxy IV satellite, located at 99 degree west longitude. Available bandwidth is Mbps Coverage: 48 U.S. continental states and Canada (open on October 1, 1995 by HNS and Telesat Canada) 23 DirecPC 24 12

13 DirecPC Services Turbo Internet high speed access to the Internet Package Delivery Electronic catalog Reuters news wheel Software delivery Multimedia CNN Headline News Financial Ticker Sports Ticker others 25 Internet 26 End user PC 13

14 Equipment needed for DirecPC A DirecPC access kit (DAK) 24 inch dish ISA adapter card (allowing a PC to receive satellite data via the DirecPC s Network Operations Center) DirecPC software and users manuals An IBM-PC compatible 486DX-66 or higher computer 8Mbytes RAM or more 500Mbytes HD or more 27 The future of DBS-integrated services digital broadcasting ISDB is a future broadcasting system that provides viewers with a variety of services. Flexibility: capable of integrating various services of different transmission capacities, speeds, etc. Extendibility: capable of adding new services. Interoperability: easy interfacing with other broadcasting systems through different transmission media. Program reception: enable viewers to select desired programs easily using an integrated receiver for all services

15 Satellite Constellations Voice Iridium, Globalstar, ICO, Inmarsat Mini-M, Super GEOs / Ellipso Constellation / Odyssey Broadband data Teledesic, Skybridge, Orblink / M-Star Celestri / GIPSE Rostelesat / Spaceway Astrolink Cyberstar Euroskyway, GESN KaStar Worldspace Aster V-Stream / WEST Voicespan / Undersea fibre Concert / Sky Station HALO, Skysat Messaging Orbcomm Final Analysis Leo One E-Sat KITComm Courier / LEqO Picosat / Starsys Navigation GPS Glonass / GNSS 29 Iridium 30 15

16 Iridium Satellites 66 Cost per Sat $62 million Altitude 785 km Planes 6 Orbit Circular Mobile MHz 1616/1616 Ground MHz Ka Band Channels/sat 3,840 Min El. Angle 8.2o Stabilization 3 Axis Weight 1,100 lbs Antenna Beamed Phased Array 31 Teledesic 32 16