A survey of handover algorithms in DVB-H <s>  <s> Handover is the mechanism that transfers an ongoing call from one cell to another as a user moves through the coverage area of a cellular system. As smaller cells are deployed to meet the demands for increased capacity, the number of cell boundary crossings increases. The author presents an overview of published work on handover performance and control and discusses current trends in handover research. He discusses investigations that are applicable to a single tier of cells. He focuses on macrocells, but includes a brief discussion on how things change as cell sizes shrink. By assuming an overlay of macrocells and microcells he summarizes issues and approaches unique to such systems. <s> BIB001 </s> A survey of handover algorithms in DVB-H <s>  <s> Utilising the DVB-T specification fully will allow broadcasters choose from different modulation formats including QPSK for transmission of MPEG-2 signals over difficult media. Very rugged signals with excellent power and echo performance can be selected with DVB-T modems for contribution circuits. This paper details preliminary results of the transmission of a 6 Mbit/sec MPEG-2 signal from a mobile vehicle to a main station on an upper adjacent channel to existing PAL I broadcasts. It shows that it is possible to use DVB-T signals for contributions from mobile transmitters without signal degradation. <s> BIB002 </s> A survey of handover algorithms in DVB-H <s>  <s> Television reception is the next challenge mobile handheld terminals will face, which already receive FM radio and can access to Internet. User cases include relaxation at idle times during travels, video information services for business users, entertainment clips and cartoons. This paper introduces two different wireless technologies, DVB-H and MBMS, which can be used to receive digital television in handheld devices. The paper presents both technologies as feasible solutions for the video broadcasting scenario, compares their performance, and it finally tells about their limitations. <s> BIB003 </s> A survey of handover algorithms in DVB-H <s>  <s> DVB-H (Digital Video Broadcasting for Handhelds) is a standard specified by the DVB Organization specifically for the broadcast of TV-like content and data to handheld devices, such as mobile phones, which have unique requirements in terms of power consumption, screen-size and mobility. Seamless handover in such a unidirectional network is especially challenging. In this paper we describe the handover issues of DVB-H networks and propose a novel seamless soft handover mechanism based on measuring CDF (Cumulative Distribution Function) of the signal to noise ratio (SNR) in the DVB-H terminal receiver front-end . Details of the algorithm is given and simulation is done to prove the benefits of such soft <s> BIB004 </s> A survey of handover algorithms in DVB-H <s>  <s> This presentation discussed the issues, technologies, and spectrum implications of broadcast technologies for mobile TV. The presentation aims to address such broadcasting dilemmas as limited battery capacity, limited processing power, and competing demands for antenna/silicon space. It also gives the advantages and disadvantages of the following technologies: DVB-H, DMB, and FLO. <s> BIB005 </s> A survey of handover algorithms in DVB-H <s>  <s> This paper describes an experiment that evaluated the feasibility and advantages of mobile data broadcasting services that will be launched in Japan in 2006. Network-linked services and location-aware services are distinct applications of the mobile broadcasting services. The network-linked services will enable users to obtain content data from broadcast and communication networks, while the location-aware services provide each user with location-based information. The experiment was performed with the prototype receivers receiving actual broadcast waves and data from the mobile Internet. The trial service contents and the prototype broadcast system were also developed. We discuss the appropriate distribution of broadcast and network content. <s> BIB006 </s> A survey of handover algorithms in DVB-H <s>  <s> This paper introduces T-DMB transmission system in Korea based on Eureka-147 DAB and presents a new architecture of transmission system for digital multimedia services. For transmission of the digital multimedia contents in mobile environment by using the existing DAB, we developed a T-DMB processor which performs T-DMB encoding and insertion of the media stream into the existing DAB transmission system. After the implemented T-DMB processor can be connected to the front of the commercial Eureka-J47 DAB system, and the performance of the T-DMB system is confirmed through the T-DMB experimental broadcasting in Korea. <s> BIB007
igital Video Broadcasting -Terrestrial (DVB-T) was not only designed for transmitting TV-like video contents but also for transmitting data services [1] [2] [3] . Digital Video Broadcasting -Handheld (DVB-H) [4] [5] [6] , formerly known as "DVB-X" [7] , is a unidirectional communication technology based on DVB-T. DVB-H and DVB-T were developed by the organization called DVB Project [8] . Recently, the DVB ad-hoc group Convergence of Broadcast and Mobile Services (CBMS) developed IPDC (IP Datacast)  over the DVB-H standard [10] , which is currently being processed by the European Telecommunications Standards Institute (ETSI). The IPDC over DVB-H standard complements the DVB-H standard by defining OSI layers 3-7 and refining some of the OSI layer 2 specific protocols, especially Program Specific Information (PSI) and Service Information (SI). DVB-H poses novel challenges for handover research. Before talking about the origin of the handover issues in DVB-H it is necessary to take a look at the services that are transmitted in DVB-H networks. The service contents in DVB-H networks are delivered in the form of IP datagrams using IP-based mechanisms or in the form of other network layer datagrams encapsulated into Multi-Protocol Encapsulation (MPE) sections  . This kind of service is called IPDC. Although IPDC services can be offered via existing GPRS or UMTS cellular networks by Multimedia Broadcast/Multicast Service (MBMS) [12] BIB003 [14] , MBMS is only suitable for light traffic services such as short video clips. For heavy-duty streaming services, DVB-H is a better solution because of its higher bit rate compared with that of MBMS.  . IPDC brings new characteristics for DVB-H networks. The benefits are as follows [16] : • IPDC provides a platform for true convergence of services between DVB-H and cellular telecommunication networks (GPRS/UMTS). • IPDC allows the coding to be decoupled from the transport layer, thus opening the door to a number of features benefiting handheld mobile terminals, including a variety of encoding methods which only require low power from a decoder (decoding high-bandwidth MPEG-2 encoded streaming video/audio is relatively power consuming). • IPDC is relatively insensitive to any buffering or delays within the transmission (unlike MPEG-2). • IPDC is well-suited for time-sliced transmission. In a word, an IPDC service is suitable for handover in DVB-H. But what are the advantages of mobile reception of DVB-H compared to that of DVB-T? VALIDATE [17] and MOTIVATE  were two European projects that addressed the issues of mobile reception of DVB-T signals BIB002 . Laboratory tests and field trials have shown that mobile applications of DVB-T are feasible using the code rate equals 1/2 modes of the specification  . However, the tests of receivers also showed the limits of performance achievable for mobile television using DVB-T without enhancements to the receivers  . In addition, the power consumption of mobile reception of DVB-T is a big issue for battery powered terminals  BIB005 . DVB-H is the technique that was rolled out for the mobile portable reception of IPDC contents [24, 25] . Similar standards are used in Japan and Korea for mobile data broadcasting BIB006 BIB007 . The scenario of single-frequency DVB-H networks consists of high-power DVB-H transmitters like those of DVB-T. However, multifrequency networks comprised of low power DVB-H transmitters are also expected to be a typical network scenario for DVB-H. With decreasing cell size, handover in DVB-H becomes a critical issue. Handover in traditional cellular telecommunications networks (like GSM) refers to the mechanism that transfers an ongoing call from one cell to another as a user moves through the coverage area of the cellular system BIB001 and has long been a research topic. However, handover in DVB-H refers to the switching of the reception of IP-based services from one transport stream to another when the terminal moves through the coverage area of a DVB-H network [29] . In this survey the two different terms "channel" and "transport stream" are used for the same meaning. They both mean the path along which a communications signal is transmitted. Soft handover is usually used to mean that radio links are added and removed in such a way that the device always keeps at least one radio link to the base station BIB004 . In DVB-H, this means that the received frequency and/or transport stream is changed without interruption of the ongoing reception. It is considered important for researchers in the DVB-H area to understand the importance of handover, especially in multifrequency DVB-H networks. Therefore, this article provides a comprehensive survey of various aspects of the handover algorithms in DVB-H networks. The article is structured as follows. We describe the technical features of DVB-H. Then a detailed introduction to handover in DVB-H is given and the differences between handover in DVB-H, DVB-T and cellular telecommunications networks are presented. Next, the authors' approaches to handover research in DVB-H are described with the handover challenges and handover stages followed. The different handover algorithms currently available are investigated. The authors' view of how to design a handover algorithm for DVB-H is presented. Finally, the article closes with the conclusions and a discussion of the projects related to and the research trends in handover algorithms in DVB-H networks.