In this paper, we present an analytical method for effectively evaluating the channel utilization of voice calls in voice over WLAN systems. The method is under realistic assumptions general enough to deal with various cases of mixed traffic sources and transmission conditions. The accuracy and effectiveness of our method are validated through experiments. The method provided a basis for a prototype call-admission-control system for VoWLAN, in an attempt to enable an operational VoWLAN system with quality-of-service support.
We present a producer-consumer model of multimedia-on-demand (MOD) servers. The producer retrieves media data from a disk and places it into a set of buffers, while the consumer sends out the data in the buffers to the users. We develop for the producer a buffer-inventorybased dynamic scheduling (BIDS) algorithm that guarantees non-zero inventory and non-overflow of data in the buffers to meet the continuity requirement and no-loss of data for each media stream. The algorithm can deal with heterogeneous me dia streams as well as the transient circumstances upon service completions and arrivals of new requests. To smooth out the impact of bursty data of variable-bit-rate media streams and therefore increase the maximum admissible load of requests, we also introduce into the scheduling scheme a time-scale-dependent peak consumption rate and a virtual cycle time. Based on BIDS, an effective admission control mechanism can be easily established by checking two simple conditions respectively on the overall system load and buffer size. Our algorithm is very easy to implement. Experiments carried out with an actual disk system and real video stream data verify that it is more robust compared to static scheduling algorithms previously proposed in the literature, especially when handling variable-bit-rate media streams.
We present a producer-consumer model of multimediaon-demand servers, The producer retrieves media data from a disk and places it into a set of buffers while the consumer sends out the data in the buffers to the users. We develope for the producer a time-scale dependent buffer-inventory-hirsed dynamic scheduling scheme named o-BIDS which gunrunteesto meet the continuityrequiremcnt and no-lossof datn for each media stream. The scheme introduces a time-scale dependent peak consumption rate and a virtual cycle time to smooth out the impact of bursty data of variable-bit-raie streams, thus improving the maximum admissible load of requests. A straighlforward admission control mechanism with quality-of-service guarantees is then established based on two simple conditions respectively on loud and bufier size. Our scheduling scheme is very easy to implement, and experiments carried out with an actual disk system and rei11 video stream data verifr the effectiveness of the scheme.
In this paper, we give a quantitative evaluation on the effect of integrating WiMAX and Wi-Fi, as compared to the case of separate WiMAX and Wi-Fi systems, on the system capacity with QoS being considered. We focus particularly on the VoIP traffic aspects of the system. Based on this capacity evaluation, a cost analysis is further presented. We also propose and analyze a resource management scheme on Wi-Fi to WiMAX handover.
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