An Experimental Investigation of Parallel Multimedia Streams Over IEEE 802.11e WLAN Networks Using TXOP

Abstract

-In this paper we perform an experimental investigation of the IEEE 802.11e TXOP facility to enhance the transmission of parallel multimedia streaming sessions through efficient bandwidth reservation and explicitly consider both the audio and video streams. The delay constraints associated with the audio and video streams that comprise a multimedia session pose the greatest challenge since real-time multimedia is particularly sensitive to delay as the packets require a strict bounded end-to-end delay. We show how the TXOPLimit parameter can be efficiently dimensioned to reduce the transmission delay for the video frames. Due to its frame-based nature, video applications are considered to be bursty as each video frame is typically transmitted as a burst of packets. The size of the burst is related to the size of the video frame and the number of packets required to transmit the video frame. The TXOP facility is particularly suited to efficiently deal with this burstiness since it can be used to reserve bandwidth for the duration of the packet burst. Through experimental investigation, we show that there is a significant performance improvement for the video streams by using the TXOPLimit parameter however there is no such improvement for the audio streams. We show that over-dimensioning the TXOPLimit parameter can cause the video stream to seize too much bandwidth which results in a deterioration in performance for the other competing traffic streams. This deterioration becomes more prominent as the number of parallel multimedia streams increases. We show that there is a performance improvement to all traffic streams by providing differentiated service to the constituent I, P, and B video frame types in conjunction with the TXOP facility.

Performance Tradeoff Study of Streaming Video among Vehicle

“…Video streams need to be smoothened because they can be much more bursty than VoIP (Voice over IP) streams [3,4]. This can be done by reducing the video compression rate with respect to the total traffic flow rate.…”

Investigation of H.264 Video Streaming over an IEEE 802.11e EDCA Wireless Testbed

“…Some recent work conducted experimentally in [14] investigated the effect of varying the TxOP parameter on the video quality when using data partitioning. The TxOP parameter allows for a station to send a burst of data frames at once in a single contention attempt.…”

Experimental investigation of IEEE 802.11e EDCA

“…Using (4) and the delay distribution we can calculate the expected frame delay per access category, such as AC_BK = 9.03ms, AC_BE = 2.65ms and AC_VO = 1.84ms.…”

“…Similarly in [3] the EDCA mechanism is implemented in a field programmable gate array (FPGA). In [4] the authors modify the TxOP (defined in Section II) bursting parameter to enhance multimedia transmission focussing on video transmission. VoIP capacity of a network is evaluated in [5] while modifying buffering requirements and the TxOP value.…”

“…VoIP capacity of a network is evaluated in [5] while modifying buffering requirements and the TxOP value. Both [4,5] feature hardware test-beds for the experimental work. The focus of this recent work is still on the modification and optimisation of EDCA for a specific traffic type.…”