tailieunhanh - Báo cáo hóa học: " Adjustable TXOP mechanism for supporting video transmission in IEEE 802.11e HCCA"

Tuyển tập các báo cáo nghiên cứu về hóa học được đăng trên tạp chí hóa hoc quốc tế đề tài : Adjustable TXOP mechanism for supporting video transmission in IEEE HCCA | Jansang and Phonphoem EURASIP Journal on Wireless Communications and Networking 2011 2011 158 http content 2011 1 158 Ũ EURASIP Journal on Wireless Communications and Networking a SpringerOpen Journal RESEARCH Open Access Adjustable TXOP mechanism for supporting video transmission in IEEE HCCA Aphirak Jansang and Anan Phonphoem Abstract The basic mechanism of HCCA HCF Control Channel Access has been introduced in IEEE standard to support the parameterized QoS by allocating a fixed duration based on the requested TSPEC requirements during the admission control process. However the variable bit rate VBR traffic . MPEG-2 and MPEG-4 video cannot be surely supported. In this study the adjustable TXOP mechanism for supporting video transmission ATMV has been proposed. The mechanism adaptively adjusts the TXOP duration according to a finite state machine based on feedback queue size information. The mechanism aims for prompt serving burst packets generated from the incoming video frames which finally minimizes the packet delay. Both system performance mean packet delay TXOP loss factor and channel occupancy and video quality PSNR and MOS values have been evaluated from five video clips in three categories by using the network simulator NS2 with EvalVid toolset. The results reveal that the proposed mechanism performs well for rapid movement video category and adequately supports for other video categories. Keywords IEEE quality of service variable bit rate finite state machine 1 Introduction To support quality of service QoS in IEEE 1 the IEEE task group 2 was setup. The standard has been rectified since 2005 based on its legacy IEEE Distributed Coordination Function DCF and Point Coordination Function PCF modes. Two extended modes are proposed Enhanced Distributed Channel Access EDCA and HCF Controlled Channel Access HCCA . The EDCA mode is the next generation of DCF mode that aims for supporting .