Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Research Article An Adaptive Fair-Distributed Scheduling Algorithm to Guarantee QoS for Both VBR and CBR Video | Hindawi Publishing Corporation EURASIP Journal on Advances in Signal Processing Volume 2008 Article ID 264790 12 pages doi 2008 264790 Research Article An Adaptive Fair-Distributed Scheduling Algorithm to Guarantee QoS for Both VBR and CBR Video Traffics on IEEE WLANs Saeid Montazeri 1 Mahmood Fathy 2 and Reza Berangi2 1 Computer Group Islamic Azad University KhomeiniShahr Branch Khomeinishar 84175 119 Iran 2 Department of Computer Engineering Iran University of Science and Technology Tehran 16846-13114 Iran Correspondence should be addressed to Saeid Montazeri Received 2 October 2007 Revised 15 February 2008 Accepted 16 April 2008 Recommended by Jianfei Cai Most of the centralized QoS mechanisms for WLAN MAC layer are only able to guarantee QoS parameters for CBR video traffic effectively. On the other hand the existing distributed QoS mechanisms are only able to differentiate between various traffic streams without being able to guarantee QoS. This paper addresses these deficiencies by proposing a new distributed QoS scheme that guarantees QoS parameters such as delay and throughput for both CBR and VBR video traffics. The proposed scheme is also fair for all streams and it can adapt to the various conditions of the network. To achieve this three fields are added to the RTS CTS frames whose combination with the previously existing duration field of RTS CTS frames guarantees the periodic fair adaptive access of a station to the channel. The performance of the proposed method has been evaluated with NS-2. The results showed that it outperforms IEEE HCCA. Copyright 2008 Saeid Montazeri et al. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited. 1. INTRODUCTION The wireless LAN WLAN systems have received increasing popularity in recent years because they are cost
