A survey of handover algorithms in DVB-H <s> HANDOVER DECISION-MAKING BASED ON THE HANDOVER CRITERIA <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> BIB001 </s> A survey of handover algorithms in DVB-H <s> HANDOVER DECISION-MAKING BASED ON THE HANDOVER CRITERIA <s> The 3rd generation mobile cellular communication systems will provide high-capacity bandwidth, enabling rich media and even TV services to be accessible via mobile handheld devices. For the reception of such services, seamless mobility is a must rather than an option. Alternatively, Digital Television standards, particularly data broadcasting in Terrestrial Digital Video Broadcasting (DVB-T), can be used for the delivery and reception of similar services. However, the current DVB-T standard lacks adequate methods that enable seamless mobility. In cellular delivery systems, this can be achieved by so-called soft handovers. time slicing is a recent enhancement proposed for the new - still being developed - Digital Video Broadcasting for handheld (DVB-H) standard, which together with DVB-T enables a feasible solution for soft handover to be implemented. This paper considers how time slicing can be utilized in implementing soft handover in a DVB-H receiver. An algorithm for soft handover is proposed and evaluated. <s> BIB002
In the second stage of the handover process, the DVB-H ternFigure 9. Soft handover illustration. minal will decide whether it should perform handover based on the predefined handover criteria. The most commonly used handover criteria parameters are the Received Signal Strength Indicator (RSSI) and the Signal Noise Ratio (SNR) BIB001 BIB002 . This survey article only considers MFNs, so the selfinterferences between different transmitters in SFNs will not be considered. When the RSSI or the SNR is identified as degraded to some degree from the handover measurement of the first stage, the handover decision-making process will be triggered. Taking the SNR as the handover criteria for example, once the SNR threshold margin value s_th is reached for a certain threshold time t_th, the receiver will tune to the frequency with the strongest SNR value to continue service reception. The SNR and duration threshold are shown in Fig.  11 . In addition to the physical layer parameters, it is increasingly important to take the quality of currently received IP streams as one handover criterion especially within a MFN network. This is also recognized in  16] .