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無線與行動多媒體網路 Wireless and Mobile Multimedia Networks

無線與行動多媒體網路 Wireless and Mobile Multimedia Networks. 國立中山大學 電機系 許蒼嶺 教授. Multimedia Traffic Characteristics. Traffic Types Traditional Data Traffic Image Voice, High-Quality Sound Full Motion Video Interactive Multimedia. Data Traffic. Interactive Transactions

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無線與行動多媒體網路 Wireless and Mobile Multimedia Networks

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  1. 無線與行動多媒體網路Wireless and Mobile MultimediaNetworks 國立中山大學 電機系 許蒼嶺 教授

  2. Multimedia Traffic Characteristics • Traffic Types • Traditional Data Traffic • Image • Voice, High-Quality Sound • Full Motion Video • Interactive Multimedia

  3. Data Traffic • Interactive Transactions • Banking, Airline Reservation, Insurance Processing • 30 Transactions per sec for 1000 Terminals • Very Stable and Predictable Traffic Patterns • File Transfer • From a Few Kbytes to Hundred Million Bytes • Uniform, Regular Transmission of Data at a Constant Rate • Interactive LAN Data Traffic • Interactive Response May be Relatively Sensitive to Network Delay • Real Issues for Data Traffic • Flow/Congestion Control • Error Recovery or Re-Transmission

  4. IMAGE Traffic • Major Difference from Data Traffic • Very Large Block Transfer • Response Time Between 1 - 5 sec • Transporting Image • Compression Ratio of 4 to 1 on Average • Network Load can be Reduced • On-Line Books with Illustrations • Consecutive Display of Many Images with 1 - 2 sec Apart • Unplanned Load on Network

  5. Voice and High-Quality Sound • Voice Traffic • PCM Encoding Gives 64 Kbps • Acceptable End-to-End Delay is about 90 msec • Variable-Rate Coding • Half Duplex • About 60% of One-Way Voice Conversation Consists of Silence • High-Quality Sound • CD Quality Stereo (5 Channels) Involves Very High Bit Rate • Continuous (Such as Film Soundtrack) • Delay Does not Matter as Much as Voice

  6. Full-Motion Video • A Sequence of Pictures or Frames • NTSC：525 Lines at 30 Frames per sec • PAL：625 Lines at 25 Frames per sec • High Compression Ratio • Very Little Different From the Frame Before • MPEG-2 ：I, B, and P Frames • Timing Considerations • Jitter May Affect Presentation Quality • Network Considerations • Sufficient Bandwidth via Reservation • Acceptable End-to-End Delay

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