Adaptive fast data broadcasting scheme for video-on-demand service

As we support video-on-demand (VOD) service with batching schemes, the bandwidth requirement will be very large for a popular movie. For a hot video, fast data broadcasting scheme substantially reduce the bandwidth requirements as compared with batching schemes. However, the fast data broadcasting scheme needs to predict which movie is hot. If the prediction is not accurate, the allocated bandwidth will be wasted. This paper presents a new data broadcasting scheme for VOD service. For a movie, as it is popular, the new scheme will work like the fast data broadcasting scheme to save the communication bandwidth. If there is no request for the movie, the new scheme will not allocate bandwidth for the movie. Therefore, the bandwidth allocation for a movie is always efficient whether or not the movie is popular     

A fast video-on-demand broadcasting scheme for popular videos

Broadcasting is a prospective approach to support near video-on-demand services with light communication overhead. By letting clients share channels, such approaches involve partitioning a video into segments and repeatedly broadcasting these segments in multiple channels. An early paper proposed a broadcasting scheme called RFS (recursive frequency splitting), which can significantly reduce clients' waiting time. While efficient, RFS suffers from a high computational complexity of O(nlogn), where n is the number of segments of the video, which is typically very large. This paper proposes an efficient segmentation scheme, which can significantly reduce the computational overhead by slightly sacrificing the number of segments that can be arranged as compared to RFS.     

CAR: a low latency video-on-demand broadcasting scheme for heterogeneous receivers

As different types of wireless networks are converging into an all-IP network, i.e., the Internet, it can be expected that in the near future video-on-demand (VoD) will be widely applied to many interesting services, and users can access these services using heterogeneous terminals via heterogeneous wired/wireless access networks. Many periodic broadcasting protocols have been proposed to reduce the implementation cost of VoD systems. However, most of the protocols assumed homogeneity for user terminals, while in practice, user terminals are usually quite different in their processing power, buffer space, and power. To address this problem, a few periodic broadcasting protocols providing the same video quality for all heterogeneous clients have been proposed recently. In this paper, we proposed a novel heterogeneous VoD broadcasting technique called Catch and Rest (CAR) to accommodate bandwidth heterogeneity without sacrificing user video quality. Then, we provide mathematic analysis to calculate the client bandwidth and buffer space requirements of CAR. Finally, we present our performance evaluation results for CAR. Our results show that under the same system resources (i.e., server and network bandwidth), CAR provides more uniform and acceptable service latency for all heterogeneous clients compared to previous works.     

On-channel repeater for digital television broadcasting service

This paper presents the results of tests performed by the Communications Research Center Canada (CRC) to investigate the on-channel repeater (OCR) for digital television broadcasting services using the ATSC-8VSB transmission standard. The focus has been to study the areas where the coverage of the OCR overlaps with the main transmitter. The factors involved in successful reception in these areas and their impact on the design and configuration of this kind of repeater are identified and discussed.     

Maximizing service availability for secure satellite broadcasting

Cryptography is the most suitable technique to protect the access to subscribed value‐added services for mobile applications provided through satellite broadcasting (e.g. localization and mobile TV). However, if a temporary loss of signal is experienced by receivers, not only the data streaming is compromised, but also the key management‐related messages. Hence, when the signal is received again, it is impossible for the receivers to decrypt it. One way to overcome this issue is the re‐transmission of keys to guarantee that the largest set of legitimate receivers has the updated (set of) keys. In this paper we analyze the problem of key update in a mobile user context in order to maximize the service availability. In particular, we provide the following contributions: we propose a mathematical model that captures all the relevant features of mobile users. Then, we formally prove a few novel results on the structure of the admissible rekeying sequence. These results are used to design a scheduling algorithm for key broadcasting that, according to our model, minimizes the number of mobile users that are prevented from updating their crypto keys, hence continuing accessing the service. Finally, simulation results support our theoretical findings. Copyright © 2008 John Wiley & Sons, Ltd.     

On optimal broadcasting scheme for popular video service

In order to approach a video-on-demand (VOD) service, we can allocate more bandwidth to broadcast a popular video more frequently to reduce viewers' waiting time. Using a broadcasting scheme to support a popular video periodically, in order to guarantee a given waiting time, the harmonic broadcasting scheme needs the least bandwidth in the existing schemes. In this paper, we show that using any broadcasting scheme, the minimum bandwidth requirement for the same waiting time is the same as the harmonic broadcasting scheme. Therefore, for a popular video, in order to approach a near VOD service, the harmonic broadcasting scheme is an optimal broadcasting scheme that needs the least bandwidth for a given viewers' waiting time     

Jamming to the HF broadcasting service

The Institute for Telecommunication Sciences has been actively involved in an internationally coordinated monitoring program to determine the location of emitters of harmful interference (jamming) to the high-frequency (HF) broadcast service. four monitoring programs were undertaken between October 1984 and June 1986. The procedures that have been used and the results that have been obtained are summarized. The locations of the emitters that cause jamming to the HF broadcast service are shown and selected characteristics of the jamming environment are described. The degree to which jamming that is directed to certain broadcasters adversely impacts the performance of other broadcast services that operate on the same or adjacent channels as the targeted broadcaster is examined     

日本的综合业务数字广播地面传输协议

1.引言高清晰度电视按传输媒质[1]分为地面、卫星和同轴电缆3种.对卫星和同轴电缆传输方式,各国基本已完全决定自己所采用的标准,中国分别采用欧洲的DVB-S和DVB-C标准.对于地面传输方式,美国发展比较快,1995年末形成标准,1998年末开始有线电视台播送此类节目.欧洲在1997年形成标准,日本在1998年形成标准.其它国家也在积极推进高清晰度电视地面传输协议的选择和制定,西班牙、澳大利亚、加拿大[2]和新加坡等国家分别对高清晰度电视广播进行了协议比较和场测.对于中国的地面高清晰度电视标准,有关部门正在讨论制定中,并积极进行场测试验.下面将介绍高清晰度电视地面传输协议的发展概况,同时重点介绍日本的高清晰度电视地面传输协议--综合业务数字广播地面(ISDB-T)传输协议.     

A recursive frequency-splitting scheme for broadcasting hot videos in VOD service

One way to broadcast a popular/hot video is to let multiple users share a few channels. The stress on the scarce channels can be alleviated without sacrificing viewer waiting time. One common approach is to partition the video into fixed-length segments, which are broadcast on several channels periodically. Two representative approaches are the fast broadcasting scheme and the PAGODA scheme, which can broadcast a video using k channels by having new viewers wait no longer than /spl Theta/(D/2/sup k/) and /spl Theta/(D/5/sup k/2/) time, respectively, where D is the length of the video. In this paper, we propose a new scheme, called recursive frequency splitting (RFS), that significantly improves on existing schemes in terms of viewer waiting time. Some lower bounds on the viewers' waiting time are also developed.     

Optimal video placement for hierarchical video-on-demand systems

We have been implementing a VOD system over ATM networks based on a hierarchical three-level network architecture. One of the most important design problems is how to organize video programs stored at different level of servers. In this paper, we propose an optimal video placement strategy which gives the optimal number of video copies should be stored at each level of server such that the cost function can be minimized while a lower bound of the request rejection probability for each video is guaranteed. Our major contribution is that we model the time-variant request arrivals as a non-homogeneous Poisson process     

日本广播事业的现状和发展动向

近年来，数字技术在电信领域的快速发展和广泛应用已成为使广播媒体的业务环境发生巨大变化的重要因素。在因特网快速普及、接入方式不断创新和计算机处理速度不断加快的技术背景下，在通信和广播两大公众业务领域之间出现了崭新的业务类型(业务的融合)，并具有共用网络(传输线     

UVoD: An unified architecture for video-on-demand services

Existing video-on-demand (VoD) systems can be classified into two categories: true-VoD (TVoD) and near-VoD (NVoD). TVoD systems allocate a dedicated channel for every user to achieve short latency. NVoD systems make use of multicast technologies to enable multiple users to share a single channel to reduce system cost. This paper proposes a VoD architecture called UVoD that unifies the existing TVoD and NVoD architectures by integrating unicast with multicast transmissions. A performance model of the system is derived and numerical results show that one can achieve significant performance gain over TVoD (over 500%) under the same latency constraints     

VOD系统的一种可行的解决方法--分时点播电视

对现有VOD系统的一些解决方法的可行性进行研究,并提出一种新的真点播电视（TVOD）系统的实现方案,即分时点播电视。这种类似于多任务系统的解决方案能有效地降低TVOD系统进入实用的成本和价格,并能很好地满足用户要求。     

Adaptive batching scheme for multicast video-on-demand systems

In this paper, an adaptive algorithm is developed for providing true video on demand (VoD) services in a multicast environment. In conventional batching schemes, the batching time of the system is fixed and the performance of such static schemes is highly dependent on the selection of the batching time. If the batching time is wrongly estimated, the performance of the system will be greatly degraded. Our algorithm tries to dynamically find the optimal batching time by the newly updated arrival rate so as to minimize the bandwidth requirement. The results show that the system performance of the adaptive approach is always better than the static scheme in terms of total bandwidth requirement and customer reneging probability, especially in using long batching time for the high arrival rate     

A two-level patching scheme for video-on-demand delivery

Although patching has shown to be a simple and efficient technique for immediate media on-demand delivery, there is still much scope for further improvement compared with the lower bound of the server network-I/O bandwidth requirement. In this paper, a new technique of two-level patching scheme is proposed for the first time, in which patching channels are rearranged through merging and further patching. Simulation results show that the proposed two-level patching scheme outperforms the conventional patching technique by a significant margin. It even performs better than the dynamic skyscraper algorithm over a wide range of client request rates. Furthermore, it is reasonably competitive with hierarchical multicast stream merging (HMSM) at low to modest client request rates. Most importantly, the implementation complexity of our algorithm is much lower than the skyscraper and HMSM.     

Transmission of system information and additional service data fordigital HDTV broadcasting

A transmission scheme of system information and additional data service for digital HDTV broadcasting is proposed. The proposed configuration is based on MPEG-2/DVB specifications and uses combination of both program specific information and service information to allow efficient delivery of program related information. The prototype hardware unit was implemented to transmit the proposed system information and additional data in a digital broadcasting network     

Improving cell broadcasting scheme to support multi-lingual service in wireless networks

In this paper we propose a new problem named energy-efficient multi-lingual cell broadcasting(EEML-CB) to support multi-lingual service in cell broadcasting system. We prove that the problem is NP-hard and then propose ILP model as well as a greedy algorithm named smart multi-lingual cell broadcasting (SMCB). We evaluated our heuristic by simulations.     

Using on-channel repeater to improve reception in DTV broadcasting service area

The paper presents the results of a series of tests performed by the Communications Research Centre Canada (CRC), to investigate the possibility of improving reception, by using an on-channel repeater (OCR), in areas already covered by an 8-VSB digital television transmitter. The results are then compared with those obtained at the same test locations using DVB-T transmission at various bit rates to study the impact of OCR versus reduced bit rate transmission. The results should show under which conditions it might be possible to use an OCR, instead of reducing the bit rate, to improve reception in parts of the coverage area of a main transmitter.     

Digital audio broadcasting: High-grade service quality through on-board processing techniques

A digital audio broadcasting (DAB) satellite system is presented here which provides a high-grade quality of service for some hundreds of channels. This, with minimum cost of the radio set and of the broadcasting station, greatly improves the radio broadcasting service throughout the world, especially in areas where deployment of conventional relay infrastructure is difficult and not yet cost-effective. Potential broadcasters located in the visible hemisphere can directly up-link their programming to the DAB satellites. Broadcasters can also copy each up-link channel and steer flexibility to any beam or combination of satellite beams. The paper illustrates the advantages and the feasibility of a DAB system based on geostationary satellites with on-board processing generating signals of MCPC (multiple channel per carrier) type. This multiplexing technique allows large system margins. This solution allows the satellite L-band TWTA amplifiers to be operated in saturation and eliminates the intermodulation noise associated with the transmission of FDMA channels. A powerful coding scheme has been selected to create a ‘robust’ down-link. In this way several high-power DAB channels of radio programming, with selectable data rate, are directly delivered to the users.     

Wavelength division multiplexing-based video-on-demand systems

Serving video-on-demand (VOD) traffic via isochronous transmission service is highly desirable because of the characteristics of VOD traffic. This paper proposes a mechanism to transfer VOD traffic over wavelength division multiplexing (WDM) networks by employing isochronous transmission service. Based on the proposed mechanism, the problem of scheduling isochronous and asynchronous traffic for single-star WDM networks with multiple receivers and transmitters is investigated. The lower bounds on the total switching duration and the number of switching modes for the isochronous and asynchronous traffic scheduling problem are derived. An optimal scheduling algorithm is presented for the cases where only asynchronous traffic exists; and a heuristic algorithm is also proposed for the cases where both the isochronous and asynchronous traffic coexist in the WDM networks. Simulation results indicate that the average switching duration and the average number of switching modes obtained by the proposed algorithm are close to the lower bounds, which implies that the proposed scheduling algorithm is effective