A novel fountain code-based mobile IPTV multicast system architecture over WiMAX network

In this paper, we present a novel fountain code-based mobile IPTV multicast system architecture over WiMAX network. In the proposed system, the transmission algorithm at a base station determines the control parameters of a fountain-encoded IPTV multicast stream adaptively to the wireless link states of subscribers in order to provide a stable IPTV service with minimum resource usage on WiMAX network, and the channel grouping algorithm at a server makes near-optimal channel grouping based on channel selection preferences to pursue an effective tradeoff between the channel zapping time and the processing complexity of a subscriber. Finally, experimental results are provided to show the performance of the proposed system.     

Combining the rate adaptation and quality adaptation schemes for wireless video streaming

Video streaming service over wireless networks is a challenging task because of the changes in the wireless channel conditions that can occur due to interference, fading, and station mobility. Moreover, the IEEE 802.11 WLAN standard does not contain any specifications for the rate adaptation scheme which are useful for improving the wireless link utilization. To provide efficient wireless video streaming service, the rate adaptation scheme should be applied at the low layer and the quality adaptation scheme should be considered at the high layer. To meet this requirement of wireless video streaming, we propose a new cross-layer design for video streaming over wireless networks. This design includes the rate adaptation scheme in the data link and physical layers and the quality adaptation scheme in the application layer. The rate adaptation scheme adjusts the data transmission rate based on the measured RSSI at the sender-side and informs the quality adaptation scheme about the rate limits. Then the quality adaptation scheme utilizes this rate limits to adjust the quality of the video stream. Through performance evaluations, we prove that our cross-layer design improves the wireless link utilization and the quality of the video stream simultaneously.     

Optimizing the ARQ performance in downlink packet data systems with scheduling

Third generation wireless systems typically employ adaptive coding and modulation, scheduling, and Hybrid Automatic Repeat reQuest (HARQ) techniques to provide high-speed packet data service on the downlink. Two main considerations in designing such a system are algorithms for the selection of coding and modulation schemes based on the channel quality of the link and algorithms for the selection of the user to whom a particular slot is assigned. We propose a systematic approach to optimize the mapping between signal-to-interference-and-noise ratio (SINR) and modulation and coding scheme (MCS) to maximize the throughput by taking into account the type of HARQ scheme employed. We also propose to incorporate frame error rate (FER) and retransmission information as a part of the scheduling decision. The proposed scheduler ranking methods based on using an effective rate rather than the instantaneous rate provide natural priority to retransmissions over new transmissions, and priority to users with better channel quality. Extensive simulation results comparing performance of the proposed methods to conventional methods are presented.     

End-to-end optimized TCP-friendly rate control for real-time video streaming over wireless multi-hop networks

Rate control is an important issue in video streaming applications. The most popular rate control scheme over wired networks is TCP-Friendly Rate Control (TFRC), which is designed to provide optimal transport service for unicast multimedia delivery based on the TCP Reno’s throughput equation. It assumes perfect link quality, treating network congestion as the only reason for packet losses. Therefore, when used in wireless environment, it suffers significant performance degradation because of packet losses arising from time-varying link quality. Most current research focuses on enhancing the TFRC protocol itself, ignoring the tightly coupled relation between the transport layer and other network layers. In this paper, we propose a new approach to address this problem, integrating TFRC with the application layer and the physical layer to form a holistic design for real-time video streaming over wireless multi-hop networks. The proposed approach can achieve the best user-perceived video quality by jointly optimizing system parameters residing in different network layers, including real-time video coding parameters at the application layer, packet sending rate at the transport layer, and modulation and coding scheme at the physical layer. The problem is formulated and solved as to find the optimal combination of parameters to minimize the end-to-end expected video distortion constrained by a given video playback delay, or to minimize the video playback delay constrained by a given end-to-end video distortion. Experimental results have validated 2–4 dB PSNR performance gain of the proposed approach in wireless multi-hop networks by using H.264/AVC and NS-2.     

Improving IPTV Forwarding Mechanism in IEEE 802.16j MMR Networks Based on Aggregation

Internet protocol television (IPTV) service depends on the network quality of service (QoS) and bandwidth of the broadband service provider. IEEE 802.16j mobile multihop relay Worldwide Interoperability for Microwave Access networks have the opportunity to offer high bandwidth capacity by introducing relay stations. However, to actually satisfy QoS requirements for offering IPTV services (HDTV, SDTV, Web TV, and mobile TV) for heterogeneous users' requests, providers must use a video server for each IPTV service type, which increases the network load, especially bandwidth consumption and forwarding time. In this paper, we present a solution for forwarding IPTV video streaming to diverse subscribers via an 802.16j broadband wireless access network. In particular, we propose a new multicast tree construction and aggregation mechanism based on the unique property of prime numbers. Performance evaluation results show that the proposed scheme reduces both bandwidth consumption and forwarding time.     

Engineering wireless broadband access to IPTV

IPTV is now extending to wireless broadband access. If broadband video streaming is to achieve competitive quality the video stream itself must be carefully engineered to cope with challenging wireless channel conditions. This paper presents a scheme for doing this for H.264/AVC codec streaming across a WiMAX link. Packetization is an effective tool to govern error rates and, in the paper, source-coded data-partitioning serves to allocate smaller packets to more important data. A packetization strategy is insufficient in itself, as temporal error propagation should also be addressed by insertion of intra-coded data. It may be necessary to include redundant packets when channel conditions worsen. The whole should be protected by application-layer rateless coding. Therefore, the contribution of the paper is a complete scheme comprised of various protection measures aimed at robust IPTV streaming. Due to computational overheads, the scheme is aimed at the new generation of smartphones with GHz CPUs.     

Link Adaptation Using Dynamically Allocated Thresholds and Power Control

Link adaptation technique, in which the modulation and coding used in a communication system is changed as per the channel conditions is a very well investigated topic for link throughput maximization with widespread application in wireless access networks. Most of the known algorithms dynamically adjust transmitter data rate by comparing instantaneous SNR with pre-defined SNR switching thresholds, in order to maximize throughput while maintaining the desired quality of service. However, the use of incorrect or stale values of these pre-defined switching thresholds often leads to selection of erroneous modulation and coding schemes resulting in unsatisfactory throughput or quality of service. This work introduces a novel scheme which achieves the maximum possible throughput while maintaining the target quality of service by dynamically acquiring the threshold values of different modulation and coding schemes used in the system for a given value of block error rate based on measurement at the receiver. This helps in keeping the threshold look up table up to date, so that proper threshold values for mode switching is present for all channel conditions. Also, a relationship between the throughput and the accuracy of the threshold value calculation is provided so that these can be optimized depending on the user requirements. The performance evaluation shows that the proposed system outperforms the conventional link adaptation in various operating scenarios where pre-determined look up tables are not available.

     

A Scalable Information Security Technique: Joint Authentication-Coding Mechanism for Multimedia over Heterogeneous Wireless Networks

There have been increasing concerns about the security issues of wireless transmission of multimedia in recent years. Wireless networks, by their natures, are more vulnerable to external intrusions than wired ones. Therefore, many applications demand authenticating the integrity of multimedia content delivered wirelessly. In this work, we propose a framework for jointly authenticating and coding multimedia to be transmitted over heterogeneous wireless networks. We firstly provide a novel graph-based authentication scheme which can not only construct the authentication graph flexibly but also trade-off well among some practical requirements such as overhead, robustness and delay. And then, a rate-distortion optimized joint source-channel coding (JSCC) approach for error-resilient scalable encoded video is presented, in which the video is encoded into multiple independent streams and each stream is assigned forward error correction (FEC) codes to avoid error propagation. Furthermore, we consider integrating authentication with the specific JSCC scheme to achieve a satisfactory authentication results and end-to-end reconstruction quality by optimally applying the appropriate authentication and coding rate. Simulation results show the effectiveness of the proposed authentication-coding scheme for multimedia over wireless networks.     

A generalized Chinese remainder theorem-based proactive multi-secret sharing scheme for global wide area network

Adaptive communication for is one of the hottest areas of research in the telecommunication systems including wireless broadcast systems. This is primarily accomplished for sake of boosting the transmission throughput with enhanced quality of service and ideal link utilization. In adaptive communication, various radio transmission parameters like modulation symbol, code-rate and power etc. are carefully chosen according to the erratic channel state information on the link. Digital video broadcast—second generation (DVB-S2) has an inbuilt support for adaptive coding and modulation (ACM). However, power adaptation is still a necessity because of power constraint in downlink where satellite has a limited power bank. Moreover, different downlinks have distinct transmit power requirements due to diverse ambient on earth receivers like rainy, foggy, stormy and with clear sky etc., hence flat transmit power distribution among all the ground receivers may not be a good idea at all. To utilize the ACM feature in DVB-S2 and to additionally adapt power, in this paper, an adaptive modulation, coding (MODCOD) and power scheme is proposed. By investigating a fuzzy system and differential evolution algorithm, to select the set of MODCODs and optimum power vector, respectively, for the next transmission interval. From the simulation results it is apparent that the proposed scheme is promising in terms of efficient link and transmit power utilization as well as quality of service compared to the schemes in the literature with flat power distribution.

     

纠正DPPM中插入删节错误的纠错码方案

采用差分脉冲位置调制（DPPM）的无线光通信中存在插入和删节错误。针对该类错误,提出了一种可纠正同步错误的编译码方案。DPPM的码片翻转会造成当前符号中比特的插入/删节及后续符号中比特的替代错误,替代错误总是伴随插入／删节错误发生。针对这种特殊的错误形式,通过删剪卷积码扩展网格图中的禁用路径,设计了改进的维特比译码算法。该方案不需要改变已有的卷积码编码方法,所设计系统的发端和传统的发端一致。结果表明,相比于未编码系统。所提出方案可有效降低误帧率．获得明显的性能增益。     

QoE-aware mobile IPTV channel control algorithm over WiMAX network

In this paper, we present an effective IPTV channel control algorithm that improves the quality of experience for subscribers to mobile IPTV services over WiMAX network. We consider the video quality of TV channels and the channel zapping time as quality of experience metrics. The proposed algorithm controls the channel distribution state and the target bit rate of TV channels based on the channel preference information of subscribers to achieve an effective trade-off between channel zapping time and video quality. Finally, simulation results are provided to demonstrate the performance of the proposed system.     

SSIM-based error-resilient cross-layer optimization for wireless video streaming

The traditional Sum of Squared Error (SSE)-based cross-layer optimization has been shown to be an effective way to improve the quality of service for wireless video streaming. However, recent research works show that the SSE-based optimization metric does not always provide the video distortion measurement that matches well with the video quality degradation observed by the human vision system. Taking advantage of the Structural SIMilarity (SSIM) metric in measuring the video perceptual quality, a SSIM-based error-resilient cross-layer optimization scheme is proposed to improve the perceptual quality for the real-time wireless video streaming in this paper. Besides the video data rate adjustment and the link adaption including the Modulation and Coding Scheme (MCS) selection, the error-resilient Rate-Distortion Optimization (RDO) for each encoding unit is introduced into the cross-layer optimization process to ensure that the video data are transmitted efficiently and reliably over the time-varying wireless channel. In addition, to ensure that cross-layer optimization scheme is more practical, a low-complexity optimal parameter selection algorithm that exploits the MCS-SNR relationship and the Rate-Quantization (R-Q) model is proposed. Experimental results show that significant performance improvements in terms of the perceptual video quality and the computational complexity are achieved for the proposed cross-layer optimization scheme.     

Cross-layer optimized authentication and error control for wireless 3D medical video streaming over LTE

3D video for tele-medicine applications is gradually gaining momentum since the 3D technology can provide precise location information. However, the weak link for 3D video streaming is the necessary wireless link of the communication system. Neglecting the wireless impairments can severely degrade the performance of 3D video streaming that communicates complex critical medical data. In this paper, we propose systematic methodology for ensuring high performance of the 3D medical video streaming system. First, we present a recursive end-to-end distortion estimation approach for MVC (multiview video coding)-based 3D video streaming over error-prone networks by considering the 3D inter-view prediction. Then, based on the previous model, we develop a cross-layer optimization scheme that considers the LTE wireless physical layer (PHY). In this optimization, the authentication requirements of 3D medical video are also taken into account. The proposed cross-layer optimization approach jointly controls and manages the authentication, video coding quantization of 3D video, and the modulation and channel coding scheme (MCS) of the LTE wireless PHY to minimize the end-to-end video distortion. Experimental results show that the proposed approach can provide superior 3D medical video streaming performance in terms of peak signal-to-noise ratio (PSNR) when compared to state-of-the-art approaches that include joint source-channel optimized streaming with multi-path hash-chaining based-authentication, and also conventional video streaming with single path hash-chaining-based authentication.     

Progressive image transmission over space-time coded OFDM-based MIMO systems with adaptive modulation

This paper considers a progressive image transmission system over wireless channels by combining joint source-channel coding (JSCC), space-time coding, and orthogonal frequency division multiplexing (OFDM). The BER performance of the space-time coded OFDM-based MIMO system based on a newly built broadband MIMO fading model is first evaluated by assuming perfect channel state information at the receiver for coherent detection. Then, for a given average SNR (hence, BER), a fast local search algorithm is applied to optimize the unequal error protection design in JSCC, subjected to fixed total transmitted energy for various constellation sizes. This design allows the measurement of the expected reconstructed image quality. With this end-to-end system performance evaluation, an adaptive modulation scheme is proposed to pick the constellation size that offers the best reconstructed image quality for each average SNR. Simulation results of practical image transmissions confirm the effectiveness of our proposed adaptive modulation scheme.     

Cross-layer resource allocation for integrated Voice/Data traffic in wireless cellular networks

A major task in next-generation wireless cellular networks is provisioning of quality of service (QoS) over the bandwidth limited and error-prone wireless link. In this paper, we propose a cross-layer design scheme to provide QoS for voice and data traffic in wireless cellular networks with differentiated services (DiffServ) backbone. The scheme combines the transport layer protocols and link layer resource allocation to both guarantee the QoS requirements in the transport layer and achieve efficient resource utilization in the link layer. Optimal resource allocation problems for voice and data flows are formulated to guarantee pre-specified QoS with minimal required resources. For integrated voice/data traffic in a cell, a hybrid time-division/code-division medium access control (MAC) scheme is presented to achieve efficient multiplexing. Theoretical analysis and simulation results demonstrate the effectiveness of the proposed cross-layer approach.     

有线无线融合的卫星时间敏感网络流调度研究

随着空间通信任务日趋复杂化,尤其是对时间敏感的需求不断提升,一方面要求星内系统的高带宽、可靠性和实时性;另一方面星间无线链路也应具备低时延和高可靠性.但由于卫星内部有线链路与星间无线链路差异大,业务数据经过有线和无线链路联合传输时,容易引发节点拥塞,而无法保障时敏业务的时延有界需求.为了提升数据在空间网络传输的实时性,...     

基于分层聚类分析的IPTV业务质量研究与应用

IPTV是基于IP协议的视频业务,与互联网数据业务对网络质量的要求存在很多不同,对网络带宽、QoS性能、可靠性及时延性等方面都要求更高。随着IPTV业务的推广发展和用户对业务质量要求的提高,IPTV业务质量保障变得越来越重要。因此,介绍IPTV网络承载技术,分析IPTV业务质量保障现状及不足,结合SQM系统提出了一种基于分层聚类分析的IPTV业务质量优化方案。     

Joint QoS control for video streaming over wireless multihop networks: A cross-layer approach

In this paper, we propose a novel cross-layer framework for jointly controlling and coding for multiple video streams in wireless multihop networks. At first, we develop a cross-layer flow control algorithm that works at the medium access control (MAC) layer to adjust each link's persistence probability and at the transport layer to adjust flow rates. This proposal is designed in a distributed manner that is amenable to online implementation for wireless networks, and then, a rate-distortion optimized joint source-channel coding (JSCC) approach for error-resilient scalable encoded video is presented, in which the video is encoded into multiple independent streams and each stream is assigned forward error correction (FEC) codes to avoid error propagation. Furthermore, we integrate the JSCC with the specific flow control algorithm, which optimally applies the appropriate channel coding rate given the constraints imposed by the transmission rate obtained from the proposed flow control algorithm and the prevailing channel condition. Simulation results demonstrate the merits and the need for joint quality of service (QoS) control in order to provide an efficient solution for video streaming over wireless multihop networks.     

High capacity wireless multimedia transmission with unequal error protection over Rayleigh fading channel

Efficient use of the available bandwidth and power resources for real-time multimedia transmission with high data rate and quality of service guarantee is one of the main challenges for next generation wireless systems. In image and video applications, the reception quality is highly sensitive to transmission delay, data loss, and error performance. Therefore, feasible transmission techniques over realistic channel conditions and detection methods are required to meet the increasing demands of multimedia services. In this paper, adaptive real-time communication (ARTC) system based superposition coding and layered detection is proposed for higher capacity visual data transmission over Rayleigh fading channel with unequal error protection (UEP). In the transmitter side, the source data is splitted into two streams depending on their importance, high priority and low priority. These two bit streams are modulated individually using different adjustable power allocation ratio according to partial feedback of channel state information with a constraint of total transmitted power during every symbol period. The received signal is detected using low complexity layered receiver with successive interference cancellation. To evaluate the system performance, constellation constrained capacity formula is derived. Under same resources of bandwidth, power, and time, extensive simulation results demonstrate the effectiveness of proposed ARTC scheme and shows significant improvement in capacity and bit-error-rate compared with the conventional direct single stream transmission and hierarchical modulation. Furthermore, the unequal importance characteristics of visual data are well exploited to attain reliable communication with UEP property.