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Services and Quality of Services-1

Services and Quality of Services-1. Item 2007 L A Rønningen. Mobile Telephony (circuit switched) SMS Videoconferencing Telemedicine. TV Interactive broadcast WWW Email IP telephony (?). Networked Multimedia Services, examples. Quality of Service.

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Services and Quality of Services-1

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  1. Services and Quality of Services-1 Item 2007 L A Rønningen

  2. Mobile Telephony (circuit switched) SMS Videoconferencing Telemedicine TV Interactive broadcast WWW Email IP telephony (?) Networked Multimedia Services, examples

  3. Quality of Service • Provided by a system (service platform) • Technological system • Economical system • Social system • Management • environment • Human beings

  4. Quality of Service • Definition (one of several): ”Quality of Service indicates the defined and controlling behavior of a service expressed through quantitative measurable parameter(s)” [J B Schmitt]

  5. Resource Management • Service systems normally are constrained by limited resources • Resources shall be shared between users in a fair way • The quality of the service shall be controllable (pre-defined, aggreed)

  6. QoS control • Scaling and Adaptation of media quality • MPEG-4 • Quality Shaping (see DMP later) • Resource Reservation • GSM telephony (circuit switched)

  7. Real-Time • Definition (DIN): ”A real-time process is a process which delivers the results of the processing in a given time-span”

  8. Real-time characteristics • Deadlines • Soft deadlines • Not critical if we sometimes miss deadline • Hard deadlines • Critical, system failure if missed

  9. Real-time characteristics • Predictably fast response • A high degree of schedulability • Stability under transient overload

  10. Real-time characteristics (details) • Multi-tasking • No blocking of real-time tasks • Short Interrupt Delays • Fast Context Switching • Control of Memory Management • Guarantee of response time • Proper Scheduling • OS support for time-constrained tasks • Fine Granularity of Timer Service • Microseconds, milliseconds • Rich Set of InterTask Communication Mechanisms • Time-sensitive OS kernel mechanisms

  11. QoS Layering User Perceptual QoS Application Application QoS System System QoS Devices Network Network QoS Device QoS

  12. QoS Specification, Design and Implementation • Traffic • Troughput, utilization, delay, inter-event time, event rate, number of customers (packets, jobs, tasks,), congestion • Reliability, availability • Operation and maintenance • Security • Human factors (user interface) • Social factors • Economic factors

  13. Perceptual QoS • Description of perceptive qualities • Media quality (excellent,,,bad) (near-natural,,,,) • Frame size (large,,, small) • Stereoscopic (auto-) • Multiview (number of views) • Security (high,,, low) • User interface (excellent,,, bad) • Pricing choices • How much is a user willing to pay for a service with a certain quality

  14. Application QoS parameters • Media quality • Temporal and Spatial resolution of objects, frames, scenes • Number of autostereoscopic views • End-to-end delay, jitter • User focus on objects, fovation • Quality adaptation rules or profiles (e.g. vs traffic)

  15. System QoS parameters • CPU and GPU Requirements • Processing time • Period Time • CPU Utilization • Memory Requirements • Space • Access time • Cycle time • Communication Requirements (transport) • Packet rate • Packet size • Capacity (bandwidth) • End-to-end delay

  16. Network QoS parameters • Link capacity • Network load (link utilisation) • Interarrival time • Burstiness • Autocorrelation of streams • Transient streams • Stationary streams • Periodicity of streams • Packet size • Node service time • Packet loss (drop) • Propagation delay

  17. Device QoS parameters • System-QoS parameters • Other hardware requirements • Loadspeakers • Video capture boards • ,,,,,

  18. Service Classes • Guaranteed quality • Predictive quality • Best effort quality

  19. Guaranteed QoS • Specified through QoS parameter values • deterministic • Statistical • Single value - average (threshold, target) • Pair of values - interval • Triple of values - max, mean, min

  20. Video QoS parameter range Min spatial resolution Max spatial resolution Max frame rate Frame Rate (temporal resolution) Acceptable region Min frame rate Unacceptable region Spatial resolution

  21. Predictable service • Parameter bounds based on history, that is, past network behavior • Parameter values are measured, and certain statistical analyses may be carried out

  22. Best effort services • No guarantees of quality, no QoS parameter values • Partial guarantees, some QoS parameter values are given

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