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1.
Naveen Chilamkurti Sherali Zeadally Robin Soni Giovanni Giambene 《Multimedia Tools and Applications》2010,47(1):189-205
The use of wireless networks has spread further than simple data transfer to delay sensitive and loss tolerant multimedia
applications. Over the past few years, wireless multimedia transmission across Wireless Local area Networks (WLANs) has gained
a lot of attention because of the introduction of technologies such as Bluetooth, IEEE 802.11, 3G, and WiMAX. The IEEE 802.11
WLAN has become a dominating technology due to its low cost and ease of implementation. But, transmitting video over WLANs
in real time remains a challenge because it imposes strong demands on video codec, the underlying network, and the Media Access
Control (MAC) layer. This paper presents a cross-layer mapping algorithm to improve the quality of transmission of H.264 (a
recently-developed video coding standard of the ITU-T Video Coding Experts Group) video stream over IEEE 802.11e-based wireless
networks. The major goals of H.264 standard were on improving the rate distortion and the enhanced compression performance.
Our proposed 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. We evaluate the performance of our proposed cross-layer design and the
results obtained demonstrate its effectiveness in exploiting characteristics of the MAC and application layers to improve
the video transmission quality. 相似文献
2.
A Cross-Layer Mapping Unequal Error Protection (CLM-UEP) mechanism is proposed for video streaming over IEEE 802.11e wireless networks. In the proposed approach, the transmitted video frames are assigned a different number of redundant packets in accordance with their video coding significance. An adaptive cross-layer mapping algorithm is then applied in the Media Access Control (MAC) layer to map the video and redundant packets to appropriate Access Category (AC) queues based on their coding significance and the network load. The numerical results show that the UEP mechanism provides an effective protection against wireless transmission losses. Moreover, the CLM algorithm maximizes the utilization efficiency of the AC queues and minimizes network congestion. As a result, a significant improvement is obtained in both the Playable Frame Ratio (PFR) and the peak signal-to-noise ratio of the transmitted video. 相似文献
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基于跨层优化和不平等保护的思想,提出一种新的IEEE 802.11e动态队列分派算法。利用AC[1]和AC[0]队列优化视频传输;根据队列状态动态计算队列优先级,并将它与视频帧优先级相匹配;综合考虑视频帧的优先级、不同队列的拥塞状况为视频帧动态分派队列。仿真实验表明,该算法能有效降低视频的传输失真。 相似文献
5.
针对H.264视频在802.11e无线网络中传输时,由丢包和编码量化引起的接收端失真问题,提出了一种以失真为驱动的跨层优化算法,以减少接收端的失真。通过率失真模型得到量化参数(QP)和量化失真之间的关系后,根据不同视频数据分区的丢包率,估计出接收端的传输失真和总体失真;然后,以这个总体失真为依据,提出一个求最优量化参数的选择算法。实验结果表明,所提方法相比只针对H.264视频不同数据分区赋予不同传输优先级的由上向下跨层架构,或者只考虑根据传输丢包率调整编码器量化参数的由下到上的跨层架构,平均峰值信噪比(PSNR)提高了1~2dB,具有更小的接收端失真。 相似文献
6.
无线接入和视频应用的日益普及使无线视频传输成为新的研究热点。随着研究的深入,跨层优化和不平等保护的思想逐渐为大多数研究所采纳。基于IEEE 802.11e协议研究无线视频传输质量的改善方法,提出一种综合考虑视频帧优先级和相对排队延时、适用于优先级数目有限的任何编码算法的视频帧调度算法。仿真实验结果表明,提出的算法具有远高于标准EDCA及其已有改进方案的平均峰值信噪比。 相似文献
7.
认知无线电网络中,次级用户选择信道的传统技术基于信道特性对传输信道进行随机选择,忽略了应用层视频业务对信道质量的要求。针对该问题提出了一种基于视频业务质量优化的信道选择技术,优化视频业务端到端的传输质量。通过最小化端到端视频失真,跨层优化综合选择物理层传输信道、自适应调制与编码模式以及应用层的编码量化参数。该方法在多信道认知无线电网络下进行了大量的视频传输仿真模拟实验。实验结果表明该方法能够比不含信道选择的跨层优化方法提高认知无线电网络下次级用户的视频传输业务客观质量1.5 dB以上。 相似文献
8.
针对随机早期检测(RED)算法在网络拥塞控制中的缺点和复杂性,提出了基于路由队列资源(缓冲)自适应的新算法(ND-RED)。该算法采用非线性丢包策略和动态调整算法参数的方法,使得路由队列长度稳定在参考值附近,从而有效控制了网络拥塞,高效地利用了资源。最后实验结果表明,ND-RED算法具有良好的稳定性,在队列控制和丢包率控制方面优于RED算法。 相似文献
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Robust streaming of video over 802.11 wireless LANs (WLANs) poses many challenges, including coping with packets losses caused by network buffer overflow or link erasures. In this paper, we propose a novel error protection method that can provide adaptive quality-of-service (QoS) to layered coded video by utilizing priority queueing at the network layer and retry-limit adaptation at the link layer. The design of our method is motivated by the observation that the retry limit settings of the MAC layer can be optimized in such a way that the overall packet losses that are caused by either link erasure or buffer overflow are minimized. We developed a real-time retry limit adaptation algorithm to trace the optimal retry limit for both the single-queue (or single-layer) and multiqueue (or multilayer) cases. The video layers are unequally protected over the wireless link by the MAC with different retry limits. In our proposed transmission framework, these retry limits are dynamically adapted depending on the wireless channel conditions and traffic characteristics. Furthermore, the proposed priority queueing discipline is enhanced with packet filtering and purging functionalities that can significantly save bandwidth by discarding obsolete or un-decodable packets from the buffer. Simulations show that the proposed cross-layer protection mechanism can significantly improve the received video quality. 相似文献
11.
马荣飞 《计算机工程与设计》2012,33(6):2156-2159
提出了适用于无线视频传感器网络的基于能量感知的跨层交互多路径协作路由技术.该技术首先采用了基于视频传感器节点感知距离的遗传优化算法,预测传输视频数据的能耗和剩余能量,结合无线信道质量和视频编码算法建立一种跨层协同的工作体系,优化节点传输视频数据的能耗、时延和带宽等因素;然后建立应用层、网络层和物理层跨层协同工作体系.仿真实验和数学分析表明,该技术不仅能够较好地满足视频传感器网络应用业务的多样性QoS数据传输性能需求,而且可以充分利用视频传感器网络受限的计算、存储能力和能量等资源. 相似文献
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In order to assure the communication quality in network systems with heavy traffic and limited bandwidth, a new ATRED (adaptive thresholds random early detection) congestion control algorithm is proposed for the congestion avoidance and resource management of network systems. Different to the traditional AQM (active queue management) algorithms, the control parameters of ATRED are not configured statically, but dynamically adjusted by the adaptive mechanism. By integrating with the adaptive strategy, ATRED alleviates the tuning difficulty of RED (random early detection) and shows a better control on the queue management, and achieve a more robust performance than RED under varying network conditions. Furthermore, a dynamic transmission control protocol–AQM control system using ATRED controller is introduced for the systematic analysis. It is proved that the stability of the network system can be guaranteed when the adaptive mechanism is finely designed. Simulation studies show the proposed ATRED algorithm achieves a good performance in varying network environments, which is superior to the RED and Gentle-RED algorithm, and providing more reliable service under varying network conditions. 相似文献
13.
抗时延敏感性跨层自适应资源分配方案* 总被引:1,自引:1,他引:0
为了对抗多用户OFDM系统中用户实时业务对时延的敏感性,提出一种利用Hopfield神经网络(HNN)算法的跨层自适应资源分配方案。该方案设置用户调度优先级时同时考虑物理层的信道状态信息,及媒体接入层的用户队列状态信息和等待时间等;采用HNN算法,最大化系统容量的同时降低了平均时延和丢包率。仿真结果表明,相比于传统资源分配方案,该方案可以有效保障用户的服务质量,并提高了系统的整体性能。 相似文献
14.
基于IEEE802.11DCF提出了一种应用于无线自组网的媒质接入控制协议,该协议包括网络适应性退避算法和拥塞反馈两个关键机制。协议的主要思想是根据节点周围实际竞争状况和网络拥塞情况进行包调度。仿真结果表明,提出的机制有效地降低了平均端到端时延和数据丢包率,提高了信道接入公平性。 相似文献
15.
Byung Joon Oh Chang Wen Chen 《Multimedia, IEEE Transactions on》2009,11(6):1052-1061
This paper presents a cross-layer design for a reliable video transmission over wireless ad hoc networks based on multichannel MAC protocol with TDMA. First, we conduct a study of the multichannel MAC protocol through Markov chain model. Based on this study, two novel cross-layer modules are adopted for the design of multichannel MAC protocol. First, we adopt maximum latency rate (MLR) as the channel quality metric. Unlike the traditional MAC design based on network allocation vector (NAV), MLR is implemented to provide differentiated traffic so that the channel with smaller MLR time is initiated for higher priority traffic. Second, we adopt two congestion-aware metrics, namely MAC utilization and queue length of MAC layer, to improve the congestion-aware routing protocols with AODV and DSR. These two novel modules allow the proposed MAC protocol design to achieve high performance video transmission over wireless ad hoc networks. Experimental results show that the proposed scheme outperforms the state-of-the-art schemes under multichannel environments in wireless ad hoc networks for as much as 3.6 dB in PSNR. Such significant performance enhancement confirms that the cross-layer approach is very effective for multichannel MAC protocol design. 相似文献
16.
In this paper, we present a cross-layer approach for video transmission in wireless LANs that employs joint source and application-layer channel coding, together with rate adaptation at the wireless physical layer (PHY). While the purpose of adopting PHY rate adaptation in modern wireless LANs like the IEEE 802.11a/b is to maximize the throughput, in this paper we exploit this feature to increase the robustness of wireless video. More specifically, we investigate the impact of adapting the PHY transmission rate, thus changing the throughput and packet loss channel characteristics, on the rate-distortion performance of a transmitted video sequence. To evaluate the video quality at the decoder, we develop a cross-layer modeling framework that considers jointly the effect of application-layer joint source-channel coding (JSCC), error concealment, and the PHY transmission rate. The resulting models are used by an optimization algorithm that calculates the optimal JSCC allocation for each video frame, and PHY transmission rate for each outgoing transport packet. The comprehensive simulation results obtained with the H.264/AVC codec demonstrate considerable increase in the PSNR of the decoded video when compared with a system that employs separately JSCC and PHY rate adaptation. Furthermore, our performance analysis indicates that the optimal PHY transmission rate calculated by the proposed algorithm, can be significantly different when compared with rate adaptation algorithms that target throughput improvement. 相似文献
17.
Zheng Wan Naixue Xiong Nasir Ghani Athanasios V. Vasilakos Liang Zhou 《Multimedia Tools and Applications》2014,72(1):541-571
Packet loss of video streams cannot be avoided at wireless links for limited wireless bandwidth and frequently changed environments. To provide differentiated Quality of Service (QoS) guarantees between multimedia and data services, IEEE 802.11e was proposed. However, its performance and flexibility need to be further improved. In this paper, after a survey on various modifications of IEEE 802.11e, we formulate the problem of video transmission over IEEE 802.11e networks to help scheme design and performance analysis. Then accompanied with in-depth analysis, an adaptive unequal protection schema is proposed, which is composed of three mechanisms: (1) Insert each video packet into the access category (AC) with the minimum relative queuing delay; (2) Assign each packet dynamically to a proper AC based on several parameters to guarantee the transmission of high priority frames; (3) Apply fuzzy logic controllers to adjust parameters so as to reply quickly to the variation of video data rate, coding structure and network load. Finally, regarding MPEG-4 codec as the example, we perform extensive evaluations and validate the effectiveness and flexibility of proposed scheme. Simulations are divided into WLAN and multihop parts, involving different video sequences and various traffic modes of data streams. Beside performance comparison between proposed scheme and other ones, influence of parameter setting and combination with routing algorithms are also evaluated. 相似文献
18.
Hussein Abdel-Jaber Mike Woodward Fadi Thabtah Amer Abu-Ali 《Journal of Network and Computer Applications》2008,31(4):750-770
Due to the rapid development in computer networks, congestion becomes a critical issue. Congestion usually occurs when the connection demands on network resources, i.e. buffer spaces, exceed the available ones. We propose in this paper a new discrete-time queueing network analytical model based on dynamic random early drop (DRED) algorithm to control the congestion in early stages. We apply our analytical model on two-queue nodes queueing network. Furthermore, we compare between the proposed analytical model and three known active queue management (AQM) algorithms, including DRED, random early detection (RED) and adaptive RED, in order to figure out which of them offers better quality of service (QoS). We also experimentally compare the queue nodes of the proposed analytical model and the three AQM methods in terms of different performance measures, including, average queue length, average queueing delay, throughput, packet loss probability, etc., aiming to determine the queue node that offers better performance. 相似文献
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Network lifetime and transmission quality are of paramount importance for rate control in an energy constrained multi-hop wireless network. It is known that they depend on mechanisms that span several protocol layers due to the existing interference across collision links and the energy constrained nature of wireless nodes. Although separate consideration of these issues simplifies the system design, it is often insufficient for wireless networks when the overall system performance is required. In this paper, we present a framework for cross-layer rate control towards maximum network lifetime and collision avoidance. The main contributions of this paper are twofold. First, although the link attainable rate is typically a non-convex and non-separable function of persistent probabilities, we prove the convergence of this cross-layer algorithm to the global optimum of joint congestion control and random access algorithm under the framework of nonlinear programming. Second, by adjusting a parameter in the objective function, we achieve the tradeoff between transmission quality and network lifetime. Simulations illustrate the desirable properties of the proposed algorithm, including convergence to the global optimum, better performance than the layered scheme, desirable tradeoff between transmission quality and network lifetime. 相似文献