IPTV Systems, Standards and Architectures: Part II - Heterogeneous Networks and Terminal-Aware QoS/QoE-Guaranteed Mobile IPTV Service

We describe two main technical challenges in terms of the network and application levels for mobile IPTV service. To support a multimedia- streaming application service over a mobile network environment, we present the IP/MPLS-based NGN architecture with fixed and mobile convergence and its challenge, which is basically to support QoS for mobile IPTV ser vice. To meet the challenges for application source levels, we focus on the relationship of user terminals and video streaming sources to support user-perceived QoE, based on high- quality service between heterogeneous terminals. The techniques to meet these challenges depend on the characteristics of media processing and terminal capabilities, such as LCD panel size, resolution, video coding, and so on, in the heterogeneous network environment. To have a relationship between the two different levels, the significant factors mentioned previously are required to deliver the bandwidth coupled with a user profile to provide QoS/QoE in assured seamless mobile IPTV service on client devices.     

Device Personalisation — Where Content Meets Device

The explosive growth of the Internet has come with increasing diversity and heterogeneity in terms of access device, device capability, network access method, bandwidth, and user preferences. Most Internet services and World Wide Web content has been designed with desktop computers in mind, and often contains rich media, such as images, audio, and video. In many cases this content is not suitable for the new (often mobile) client devices because of their limitations in terms of screen size, memory, media support, connection speed, etc. These shortcomings have prompted the need to adapt the services and content of the Internet. This is broadly known as content negotiation and requires consideration of the client device's capabilities and characteristics (both hardware and software), the connection type and speed/bandwidth, and the user's preferences.     

Headlight Prefetching and Dynamic Chaining for Cooperative Media Streaming in Mobile Environments

Media streaming in mobile environments is becoming more and more important with the proliferation of 3G technologies and the popularity of online media services such as news clips, live sports, and hot movies. To avoid service interruptions, proper data management strategies must be taken by all parties. We propose a two-level framework and cooperative techniques for mobile media streaming. Headlight prefetching is for the cooperation of streaming access points to deal with unpredictable client movement and seamless hand-off. For each user, we maintain a virtual fan-shaped prefetching zone along the direction of movement similar to a vehicle headlight. The overlapping area and accumulated virtual illuminance of the headlight zone on a particular cell determine the degree and volume of prefetching on that cell. Dynamic chaining facilitates cooperation among users to maximize cache utilization and streaming benefit. On receiving a request from a client, the streaming access point starts a search for supplying partners before attempting to a remote media server. If a qualified partner is found, the client is chained to the partner and receives subsequent segments without server intervention. The client can itself be a supplying partner for other clients and naturally form a chain of users that are viewing and sharing the same media. Simulation results demonstrate that headlight prefetching and dynamic chaining can significantly decrease streaming disruptions, reduce bandwidth consumption, increase cache utilization and improve service response time.     

Transcoding media for bandwidth constrained mobile devices

Bandwidth is an important consideration when dealing with streaming media. More bandwidth is required for complex data such as video as opposed to a simple audio file. When delivering streaming media, sufficient bandwidth is required to achieve an acceptable level of performance. If the information streamed exceeds the bandwidth capacity of the client the result will be ‘choppy’ and incomplete with possible loss of transmission. Transcoding typically refers to the adaptation of streaming content. Typical transcoding scenarios exploit content‐negotiation to negotiate between different formats in order to obtain the most optimal combination of requested quality and available resources. It is possible to transcode media to a lesser quality or size upon encountering adverse bandwidth conditions. This can be accomplished without the need to encode multiple versions of the same file at differing quality levels. This study investigates the capability of transcoding for coping with restrictions in client devices. In addition, the properties of transcoded media files are examined and evaluated to determine their applicability for streaming in relation to a range of broad device types capable of receiving streaming media. Copyright © 2005 John Wiley & Sons, Ltd.     

Composable ad hoc location‐based services for heterogeneous mobile clients

This paper introduces a comprehensive architecture that supports adapting a client device's functionality to new services it discovers as it moves into a new environment. Users wish to invoke services – such as controlling the lights, printing locally, gaining access to applicationspecific proxies, or reconfiguring the location of DNS servers – from their mobile devices. But a priori standardization of interfaces and methods for service invocation is infeasible. Thus, the challenge is to develop a new service architecture that supports heterogeneity in client devices and controlled objects while making minimal assumptions about standard interfaces and control protocols. Four capabilities are needed for a comprehensive solution to this problem: (1) allowing device mobility, (2) augmenting controllable objects to make them networkaccessible, (3) building an underlying discovery architecture, and (4) mapping between exported object interfaces and client device controls. We motivate the need for these capabilities by using an example scenario to derive the design requirements for our mobile services architecture. We then present a prototype implementation of elements of the architecture and some example services using it, including controls to audio/visual equipment, extensible mapping, server autoconfiguration, location tracking, and local printer access.     

移动网络中基于两级缓存的流媒体调度算法

提出一种适用于移动通信网的两级缓存流媒体系统结构2CMSA（two—level cache mobile streaming architecture），它突破了移动流媒体系统中终端缓存空间小、无线接入网带宽窄的局限；针对2CMSA结构设计了基于两级缓存的移动流媒体调度算法2CMSS（two—level cache based mobile streaming scheduling algorithm），建立数学模型分析了其性能；仿真实验证明，与原有的移动流媒体系统相比，使用2CMSS调度算法能够有效地节省网络传输开销，降低用户启动时延。     

Piecewise Network Awareness Service for Wireless/Mobile Pervasive Computing

This paper presents a piecewise framework for network awareness service (NAS) for wireless/mobile pervasive computing. We investigate how piecewise consideration of wired and wireless elements of the framework architecture benefits service advertisement and discovery and network-awareness techniques. We also discuss scalability of the NAS framework with respect to platform computing capabilities. The framework is suitable for a wide range of computing devices, from powerful ones with multi-tasking operating systems (OS) to small ones with lightweight OS. Case studies applying the NAS framework to sensor monitoring in home networks and data streaming in pervasive multimedia computing are presented. The analytical results on the performance of the NAS framework in these case studies show that it has significant advantages over traditional network-awareness frameworks in terms of reducing wireless bandwidth consumption and saving battery energy of mobile devices.     

基于ZigBee技术的智能家居系统

通常把智能家居定义为利用计算机、网络和自动化控制技术,通过一个固定的平台将与家居生活有关的设备集成到一个系统中。系统通过无线通信技术进行各个节点和平台之间的通信,类似于一个家庭的局域网。文中设计了一种基于ZigBee技术的智能家居系统,除了能够利用ZigBee无线通信技术对室内的温湿度信息的实时感知,开关控制外,本系统还设计了视频流服务器,能够将室内的视频信息通过网络传输到远程客户端,如手机或者PC Web客户端。另外,此视频流服务器具有较强的扩展功能,能够进行各种常用协议的传输以及支持各种常见视频设备的数据采集。     

QoE in video streaming over wireless networks: perspectives and research challenges

The deployment of 3G/LTE networks and advancements in smart mobile devices had led to high demand for multimedia streaming over wireless network. The rapid increasing demand for multimedia content poses challenges for all parties in a multimedia streaming system, namely, content providers, wireless network service providers, and smart device makers. Content providers and mobile network service providers are both striving to improve their streaming services while utilizing advancing technologies. Smart device makers endeavor to improve processing power and displays for better viewing experience. Ultimately, the common goal shared by content providers, network service providers, and smart device manufactures is to improve the QoE for users. QoE is both an objective and a subjective metric measuring the streaming quality experience by end users. It may be measured by streaming bitrate, playback smoothness, video quality metrics like Peak to Signal Noise Ratio, and other user satisfaction factors. There have been efforts made to improve the streaming experiences in all these aspects. In this paper, we conducted a survey on existing literatures on QoE of video streaming to gain a deeper and more complete understanding of QoE quality metrics. The goal is to inspire new research directions in defining better QoE and improving QoE in existing and new streaming services such as adaptive streaming and 3D video streaming.     

移动网络中流媒体业务适配承载带宽的解决方案研究

YouTube、优酷、PPLive等一大批以流媒体为载体的视频网站的火爆,意味着流媒体时代的到来。然而,由于移动网络通信环境的不确定性,不能提供稳定的带宽,不能保障流媒体的业务质量。在研究流媒体业务特征、通信标准的基础上,提出一种基于移动核心网信令的,向流媒体业务平台告知移动网络无线链路实时带宽的方法。流媒体平台可根据当前带宽,及时地调整流媒体编码速率,以达到节约网络资源,改善用户业务感受的效果。     

QoE optimization for HTTP adaptive streaming: Performance evaluation of MEC-assisted and client-based methods

Seamless streaming of high quality video under unstable network condition is a big challenge. HTTP adaptive streaming (HAS) provides a solution that adapts the video quality according to the network conditions. Traditionally, HAS algorithm runs at the client side while the clients are unaware of bottlenecks in the radio channel and competing clients. The traditional adaptation strategies do not explicitly coordinate between the clients, servers, and cellular networks. The lack of coordination has been shown to lead to suboptimal user experience. As a response, multi-access edge computing (MEC)-assisted adaptation techniques emerged to take advantage of computing and content storage capabilities in mobile networks. In this study, we investigate the performance of both MEC-assisted and client-side adaptation methods in a multi-client cellular environment. Evaluation and comparison are performed in terms of not only the video rate and dynamics of the playback buffer but also the fairness and bandwidth utilization. We conduct extensive experiments to evaluate the algorithms under varying client, server, dataset, and network settings. Results demonstrate that the MEC-assisted algorithms improve fairness and bandwidth utilization compared to the client-based algorithms for most settings. They also reveal that the buffer-based algorithms achieve significant quality of experience; however, these algorithms perform poorly compared with throughput-based algorithms in protecting the playback buffer under rapidly varying bandwidth fluctuations. In addition, we observe that the preparation of the representation sets affects the performance of the algorithms, as does the playback buffer size and segment duration. Finally, we provide suggestions based on the behaviors of the algorithms in a multi-client environment.     

直播流媒体传输系统的冗余优化

摘 要: 对HTTP Live Streaming深入研究之后,发现该协议在直播流媒体传输过程中存在视频流索引文件重复传送的问题。详细阐述了服务器与客户端之间的交互过程,并通过对网络监控软件的使用,检测到交互过程中服务器传输给客户端的视频流索引文件存在较大的冗余,造成网络带宽开销增大。提出一种可行的改进方案,在.M3U8文件中添加一个#EXT-X-MEDIA-SEQUENCE-LAST标签,并使服务器和客户端都对该标签进行识别。通过对网络占用率的对比分析,改进后的方案对网络带宽的占用率明显减小,进而验证了该改进方案的可行性。     

Client-side session splice approach,a novel approach to achieving seamless handoffs for multimedia applications in mobile computing

Thanks to the invention of mobile computing technology, people nowadays can have various entertainment experiences with multi-function devices and heterogeneous network interfaces. When using multi-function devices with heterogeneous network interfaces to download and play streaming data, they maybe want to switch the communication from a network interface to another one in a device (i.e., the intra-terminal handoff), or to the network interface in another device (i.e., the inter-terminal handoff). In the handoffs, they have to manually reset or initiate the application, and then re-subscribe to the streaming service because the communication bound to the old network interface is lost. They are interrupted for a long time when watching the show. They have to remember the point or the scene played in the application before the handoff in order to re-subscribe to the streaming service after the handoff. They suffer from the troubling manual operations, especially when the handoff happens frequently to the network interfaces having limited communication ranges. When roaming through networks, accordingly, they need a way to download and play the streaming data without interruption due to handoffs. They can use the proposed Client-side Session Splice Approach (CSSA) to achieve seamless handoffs for multimedia applications in mobile computing. They can rely on the CSSA to automatically finish the handoff between network domains or homogeneous communication media in a network interface, the handoff between network interfaces in a device, and the handoff between network interfaces in different devices. For achieving seamless handoffs, they can count on the CSSA to automatically re-subscribe the streaming service on behalf of the application and smartly download the streaming data at the point or the scene played in the application just before the handoff happens. They don’t need to worry about the compatibility of the CSSA because the CSSA keeps intact applications, network infrastructures, and streaming servers. They can understand the principle, the practicability, the functionality, and the overheads of the CSSA through this paper.     

Syxaw: Data Synchronization Middleware for the Mobile Web

In this paper, we present a middleware for synchronization of opaque and structured data in a mobile and resource-constrained environment. The presented Syxaw (Synchronizer with XML-awareness) system distinguishes itself from related proposals in that it interoperates transparently with resources on the World Wide Web, and by exhibiting a model of synchronization that is both easy to understand and well suited for weak devices in a mobile and ubiquitous environment. We demonstrate the feasibility of the proposed system by considering several usage scenarios, including working on the Web and collaborative XML editing. We consider system performance on a mobile wireless device, and examine the impact of different optimization techniques to the performance. According to our analysis, Web interoperability suggests that the data share model be kept simple and conservative, and that moving functionality onto the client is advantageous. We find that the techniques of operation bundling and concurrent use of network downlink and uplink improve network utilization, but that achieving full bandwidth usage with a weak client is challenging in practice.     

基于微信小程序框架的智能能耗监测系统设计

近年来,随着移动互联网的发展以及网络普及度增高,网络传输速率加快,基于互联网的远程终端控制,远程监测,远程操作的设备技术更加成熟,远程监测控制系统的价值也逐渐凸显。此类设备能够连接互联网,通过云服务器进行数据交互,可以通过手机或者电脑设备进行远程的数据查看和硬件操作,在电力管理中,电量数据的采集和分析是最重要的一部分,在此基础上能够减少查询电量数据的人力消耗,加强电量查询的精准度,为电力管理提供更科学的方法。微信小程序的出现改变了手机软件的形态,其不一定独立存在,可以包含在微信中,十分方便。文章利用微信小程序作为客户端依托设计,设计一套基于远程控制装置的能耗监测系统。     

An Architecture for Exploiting Multihoming in Mobile Devices for Vertical Handovers & Bandwidth Aggregation

In recent years, mobile devices with multihoming capabilities i.e. equipped with multiple network interfaces have gained large scale popularity. This multihoming capability enables the mobile devices to connect with multiple diverse access networks simultaneously. However, networking protocol stack implemented in current devices is not capable of exploiting the availability of multiple network interfaces. Multihoming can be used to provide two important services: vertical handovers and bandwidth aggregation. Vertical handover enables a multihomed device to switch its connectivity from one access network to another access network without disrupting the communication session. Bandwidth aggregation enables multihomed device to achieve higher throughput by establishing simultaneous connections over multiple available network interfaces. A number of solutions have been proposed to exploit multihoming for vertical handovers and bandwidth aggregation. However, most of these solutions either require the support of additional network entities such as host agent, foreign agent, mobility gateway, proxy, etc. or they require changes in current widely deployed protocol stack in operating system kernels. Dependence on either network operator, administrator or operating system vendors hinders the large scale deployment of these solutions. This paper presents an end-to-end architecture that offers the vertical handover and bandwidth aggregation services to TCP applications. This architecture neither requires any additional network entity nor it requires the changes in current networking protocol stack in operating system kernels. The paper presents the design, implementation and performance analysis of the proposed architecture.     

End-to-end stereoscopic video streaming with content-adaptive rate and format control

We address efficient compression and real-time streaming of stereoscopic video over the current Internet. We first propose content-adaptive stereo video coding (CA-SC), where additional coding gain, over that can be achieved by exploiting only inter-view correlations, is targeted by down-sampling one of the views spatially or temporally depending on the content, based on the well-known theory that the human visual system can perceive high frequencies in three-dimensional (3D) from the higher quality view. We also developed stereoscopic 3D video streaming server and clients by modifying available open source platforms, where each client can view the video in mono or stereo mode depending on its display capabilities. The performance of the end-to-end stereoscopic streaming system is demonstrated using subjective quality tests.     

Remote walkthrough over mobile networks using 3-D image warping and streaming

A mobile walkthrough environment based on 3-D superview warping and view compensation streaming is presented. In this environment, 3-D views are rendered on the remote clients using 3-D oversized reference views and compensated on a view-on-demand basis by the graphically rendered views from the server. The view compensations (hole residuals and the depth map) are coded using a layered joint source-channel coding with unequal error corrections to protect the significant packets on noisy and erasure mobile channels. The new compensated view will then serve as a reference view for the subsequent rendering on the clients. This environment enables numerous mobile virtual applications, such as remote m-gaming, remote m-design, m-learning, m-CAD/CAM, etc., scalable to different network capabilities.     

基于IIS平滑流式处理的移动流媒体系统

针对当前流媒体传输协议在无线网络中的不足,采用IIS平滑流式处理技术设计了基于服务器/客户端模式的移动流媒体系统。详细讨地论了微软的IIS平滑流式处理协议,采用该协议传输音/视频数据,搭建了基于IIS7 Web服务器的流媒体服务,设计了一款基于Windows Phone 7智能手机的流媒体播放器客户端。通过在WiFi网络环境下测试该系统,在直播和点播两种播放模式下,客户端播放的视频画面清晰流畅。通过仿真无线网络带宽的变化,验证了IIS平滑流式处理根据客户端的可用带宽实时调整传送到客户端视频流的质量的特性。