Title :
Design trade-offs for networks with soft end-to-end timing constraints
Author :
Zhu, Haifeng ; Lehoczky, John P. ; Hansen, Jeffery P. ; Rajkumar, Ragunathan
Author_Institution :
Dept. of Electr. & Comput. Eng., Carnegie Mellon Univ., Pittsburgh, PA, USA
Abstract :
As broadband capabilities on wired, wireless and mobile phone networks proliferate, real-time multimedia traffic is expected to consume higher portions of the available bandwidth. Usage models in such networks range from low-cost VoIP to high-cost, high-quality, high-resolution video streams along with many intermediate data streams. Video flows, however, have stochastic processing requirements, and they may result in very low utilization levels if traditional real-time scheduling techniques are used. This calls for new analytical methods. In this paper, we illustrate a set of new techniques for reasoning about the lateness of such stochastic flows, and apply it to engineer a wired multihop real-time network. We make use of 4 dominant parameters to characterize the design space: end-to-end deadline, acceptable lateness, the number of hops and the network workload. Given any three of these parameters, the remaining parameter can be computed. For instance, if a stochastic flow passes through 10 nodes, its end-to-end deadline is 150 ms, and no more than 0.1% of the packets can be late, what is the maximum allowable system workload that would satisfy the lateness requirements? This maximum allowable workload can then be used to develop for the admission control policy to guarantee that the specified timeliness requirements are met. This paper provides insights into real-time network effects and rules of thumb to properly engineer a high utilization real-time EDF (earliest deadline first) network. Simulation and experimental results validate our methods. Our techniques are further applicable to heterogeneous network cases where some nodes on the flow path are bottlenecks or have cross traffic from other flows.
Keywords :
mobile handsets; multimedia communication; performance evaluation; queueing theory; real-time systems; scheduling; stochastic processes; telecommunication congestion control; telecommunication traffic; VoIP; admission control policy; broadband capabilities; heterogeneous network; high-resolution video streams; maximum allowable system workload; mobile phone networks; real-time earliest deadline first network; real-time multimedia traffic; real-time scheduling techniques; stochastic processing requirements; wired multihop real-time network; Admission control; Bandwidth; Mobile handsets; Spread spectrum communication; Stochastic processes; Stochastic systems; Streaming media; Telecommunication traffic; Timing; Traffic control;
Conference_Titel :
Real-Time and Embedded Technology and Applications Symposium, 2004. Proceedings. RTAS 2004. 10th IEEE
Print_ISBN :
0-7695-2148-7
DOI :
10.1109/RTTAS.2004.1317288