No abstract

No abstract

This paper presents a new bidirectional transmission protocol with single data frame to computing the performance of MAC layer based on IEEE 802.11n. As high as 600 Mbps of physical data rate is achieved in IEEE 802.11n where high data rate the current MAC layer leads to high performance overhead and low performance of throughput and designing the MAC layer still ongoing to achieve high performance throughput. In this study, a new bidirectional transmission protocol with single data frame has been proposed called BTDF bidirectional transmission data fragmentation, which is divided each data frame from sender to receiver and reverse into subframes and send each subframe, Packets those exceed the size threshold are divided into fragments also where the corrupted subframe will be retransmitted during the disruption of transmission. We have implemented this scheme in NS2 simulator to show the results for TCP and HDTV traffics and compared with literature.

This paper proposes a cross-layer packet scheduling scheme for QoS support in audio-video transmission with IEEE 802.11e HCCA and assesses application-level QoS and QoE of the scheduling scheme under lossy channel conditions. In the proposed scheme, the access point (AP) basically allocates transmission opportunity (TXOP) for each station in a service interval (SI) like the reference scheduler of the IEEE 802.11e standard, which is referred to as the TGe scheme in this paper. In the proposed scheme, however, the AP calculates the number of MAC service data units (MSDUs) arrived in an SI, considering the inter-arrival time of audio samples and that of video frames, which are referred to as media units (MUs), at the application layer. The AP then gives additional TXOP duration in the SI to stations which had audio or video MAC protocol data units (MPDUs) in their source buffers at the end of the previous TXOP. In addition, utilizing video frame information from the application layer, we propose video frame skipping at the MAC-level of a source station. If a station fails to transmit a video MPDU, it drops all the following video MPDUs in the source buffer until the next intra-coded frame comes to the head of the buffer. We compare the reference scheduler (TGe scheme), the proposed packet scheduling scheme with and without the video frame skipping at the source in terms of application-level QoS and QoE. We discuss the effectiveness of the proposed packet scheduling scheme from a viewpoint of QoE as well as QoS. Numerical results reveal that the proposed packet scheduling scheme can achieve higher quality than the TGe scheme under lossy channel conditions. We also show that the proposed scheduling scheme can improve the QoS and QoE by using the video frame skipping at the source. Furthermore, we also examine the effect of SI on the QoS and QoE of the proposed packet scheduling scheme and obtain that the appropriate value of SI is equal to the inter-arrival time of video frame.

No abstract

No abstract

No abstract

No abstract