Performance Analysis of Video Transmission Over IEEE 802.11a/e WLANs (original) (raw)
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Feasible HCCA Polling Mechanism for Video Transmission in IEEE 802.11e WLANs
Wireless Personal Communications, 2015
IEEE 802.11e standard defines two Medium Access Control (MAC) functions to support Quality of Service (QoS) for wireless local area networks: Enhanced Distributed Channel Access (EDCA) and HCF Controlled Channel Access (HCCA). EDCA provides fair prioritized QoS support while HCCA guarantees parameterized QoS for the traffics with rigid QoS requirements. The latter shows higher QoS provisioning with Constant Bit Rate (CBR) traffics. However, it does not efficiently cope with the fluctuation of the Variable Bit Rate (VBR) video streams since its reference scheduler generates a schedule based on the mean characteristics of the traffic. Scheduling based on theses characteristics is not always accurate as these traffics show high irregularity over the time. In this paper, we propose an enhancement on the HCCA polling mechanism to address the problem of scheduling pre-recorded VBR video streams. Our approach enhances the polling mechanism by feed-backing the arrival time of the subsequent video frame of the uplink traffic obtained through cross-layering approach. Simulation experiments have been conducted on several publicly available video traces in order to show the efficiency of our mechanism. The simulation results reveal the efficiency of the proposed mechanism in providing less delay and high throughput with conserving medium channel through minimizing the number of Null-Frames caused by wasted polls.
Robust streaming of video over 802.11 WLANs poses many challenges, including packets losses caused by network buffer overflow or link erasures, time-varying wireless channel and video content characteristics etc. To improve the performance of real-time video transmission over 802.11 WLANs, the use of cross layer design approach is required which allows communication between layers by permitting one layer to access the data of another layer, thereby facilitating the exchange of information. One of such design approach includes Application (APP) and Medium Access Control (MAC) layers considerations and is explored in this paper. This study focuses on H.264/MPEG4-AVC, the most widely accepted video coding standard and provides better quality compressed video and flexibility in compressing and transmitting video at APP layer and the retry limit settings of the MAC layer can be optimized in such a way that the overall packet losses are minimized. In this paper, the proposed Top-Down cross-layer design involves the mapping of H.264 video slices (packets) to appropriate access categories of IEEE 802.11e according to their information significance.
The bursty nature of video streaming applications is due to the frame-based structure of video and this has an important impact on the resource requirements of the WLAN, affecting its ability to provide Quality of Service (QoS) particularly under heavily loaded conditions. For video streaming applications, packet loss and packets dropped due to excessive delay are the primary factors that affect the received video quality. In this paper, we analyse the effects of contention on the performance and behaviour of video streaming applications over IEEE 802.11b WLANs. We show that as contention levels increase, the packet delay increases significantly, despite the total offered load in the network remaining the same. The increased delay is shown to be related to the MAC mechanism used in the IEEE 802.11 standard. We also show that the characteristics of the video content significantly affect the degree to which the stream is affected by contention.
Implementation Issues for a Video Streaming Server in Ieee 802.11 e Wlans
Recent years have seen a proliferation of real-time multimedia traffic over a more and more heterogeneous Internet. Video streaming at high, consistent quality over wireless links proves to be a difficult task. Several optimization techniques have been proposed and studied, mostly through theoretical analysis and simulation. This article describes the implementation of a cross-layer H.264 video streaming server and the evaluation of its performance in IEEE 802.11e WLANs. Measurements present the benefits of employing several key cross-layer mechanisms which aim to improve the video transmission quality over wireless links. A cross-layer signaling solution is implemented, which addresses important QoS issues between user-space and the kernel traffic control and device driver components. Network support for efficient multiqueue transmission is enabled in the Linux network driver. In addition, the paper discusses the implementation of an enhanced scheduling scheme for the receive-side, in order to provide prioritization of video streams over elastic traffic, and also for better control of latency and improved throughput for multimedia flows.
International Journal of Communication Systems, 2020
Hybrid coordination function controlled channel access (HCCA) is a medium to enhance quality of service (QoS) via the IEEE 802.11e standard. The main limitation of HCAA is that it is only efficient for constant bit rate (CBR) applications. This is due to the nature of its scheduler that allocates transmission opportunities (TXOPs) based on traffic stream (TS) specifications (TSPECs) that are determined during the traffic setup time. Variable bit rate (VBR) traffics used in HCCA have nondeterministic profile, making it not optimally and efficiently supported by HCCA. The result of this inefficiency is a deterioration of the transmission performance of multimedia data as well as a drop in the number of served QoS video traffics. We propose a novel approach to deal with this issue, which is the feedback-based admission control unit (FACU). FACU works by optimizing the usage of extra bandwidth to ensure optimal transmission performance of multimedia data. FACU achieves this by exploiting piggybacked information concerning sequential video frames in order to accurately assign the TXOP. The proposed approach is evaluated by utilizing various video sequences. It is demonstrated that FACU maximizes the overall number of video streams and optimizes the overall usage of the network without having any adverse effects on the QoS constraints determined.
Packet-based Polling Scheme for Video Transmission in IEEE 802.11e WLANs
Procedia Computer Science, 2016
IEEE 802.11e standard introduces HCF Controlled Channel Access (HCCA) to support quality of service (QoS) for multimedia traffics. In HCCA, the traffics scheduled according to their mean characteristics which favors the Constant Bit Rate (CBR) transmission approach. However, it does not efficiently cope with the fluctuation of the Variable Bit Rate (VBR) video streams where the traffic shows deviation from its mean during the traffic lifetime. In this paper, we propose a packet based polling mechanism to enhance the scheduling of pre-recorded VBR video streams in HCCA function. Our approach exploits feedback information about the arrival time of the subsequent video frame obtained through cross-layering approach to accurately schedule the uplink traffics. Simulation experiments reveal the efficiency of the proposed mechanism in providing less delay and high throughput while maintaining medium channel.
FAST: A channel access protocol for wireless video (and non-video) traffic
2012 20th IEEE International Conference on Network Protocols (ICNP), 2012
This paper presents the design of a new paradigm for a content-aware wireless MAC layer that is optimized for wireless video (first and foremost) while targeting fairness and stability among competing video traffic, and among video and non-video traffic. Hence, we refer to the proposed MAC frame work as the FAST (Fair And STable) protocol. FAST employs two parameters for each packet, a quality value and a time-to live value. Based on these parameters, FAST is designed on a muIticlass priority queuing system that classifies the incoming traffic according to the content of each traffic flow and further identifies different priorities within each video content. We develop analytical frameworks to formulate channel allocation based on video/non-video fairness and video stability require ments as a joint bandwidth maximization and scheduling opti mization problem. We incorporate these frameworks to design and simulate a content-aware channel access mechanism, which utilizes video traffic content classifications and users demand in conjunction with stability and fairness requirements at the MAC layer to allocate wireless channels to individual wireless users. Our simulation results show that FAST provides significant improvements in packet-loss-ratio, delay, overall fairness, and stability parameters when compared with leading access control mechanisms over 4GILTE environment. • We develop an analytical model for the average waiting time of each priority video and non-video flow at the FAST MAC layer using multiclass priority queuing sys tem.
Analytical Modeling for Delay-Sensitive Video Over WLAN
IEEE Transactions on Multimedia, 2012
Delay-sensitive video transmission over IEEE 802.11 wireless local area networks (WLANs) is analyzed in a cross-layer optimization framework. The effect of delay constraint on the quality of received packets is studied by analyzing “expired-time packet discard rate”. Three analytical models are examined and it is shown that M/M/1 model is quite an adequate model for analyzing delay-limited applications such as live video transmission over WLAN. The optimal MAC retry limit corresponding to the minimum “total packet loss rate” is derived by exploiting both mathematical analysis and NS-2 simulations. We have shown that there is an interaction between "packet overflow drop" and "expired-time packet discard" processes in the queue. Subsequently, by introducing the concept of virtual buffer size, we will obtain the optimal buffer size in order to avoid "packet overflow drop". We finally introduced a simple and yet effective real-time algorithm for retry-limit adaptation over IEEE 802.11 MAC in order to maintain a loss protection for delay-critical video traffic transmission, and showed that the average link-layer throughput can be improved by using our adaptive scheme.
2006 IEEE 17th International Symposium on Personal, Indoor and Mobile Radio Communications, 2006
The bursty nature of video streaming applications is due to the frame-based structure of video and this has an important impact on the resource requirements of the WLAN, affecting its ability to provide Quality of Service (QoS) particularly under heavily loaded conditions. In this paper we analyse this bursty behaviour in depth. We show how each video frame is queued at the AP causing the packet delay to vary in a sawtooth manner that is related to the frame rate, the number of packets per video frame, and the packet size. We infer the maximum background traffic load that can be supported so that it does not negatively impact on the video streaming application. We demonstrate that there is a critical threshold load value above which the AP can no longer reliably support the video stream and compare it to the threshold load values calculated through analysis. Using this knowledge, the AP can employ resource allocation mechanisms to regulate the incoming traffic to the AP transmission queue so that QoS can be provided for streaming applications.
An On-Off Queue Control Mechanism for Scalable Video Streaming over the IEEE 802.11e WLAN
2008 IEEE International Conference on Communications, 2008
In this paper, we study the issue of scalable video streaming over IEEE 802.11e EDCA WLANs. Our basic idea is to control the number of "active" nodes on the channel in order to reduce collisions under heavy traffic conditions. Specifically, we propose a distributed on-off queue control (OOQC) mechanism, which is designed to maintain high network throughput while keeping packet loss due to collision as low as possible. A low priority early drop (LPED) method is also employed to drop the packets at the queue according to packet relative priority index (RPI) provided by scalable video coding. Simulation results show that our proposed OOQC scheme significantly outperforms EDCA in received video quality. This full text paper was peer reviewed at the direction of IEEE Communications Society subject matter experts for publication in the ICC 2008 proceedings.