DVB SH System for Broadcasting to Handheld Devices Project proposal for EE 5359 Multimedia processing Spring 2011 Guided by Dr K R Rao Irfan Kerawalla ID 1000719155 irfan kerawalla mavs uta edu Objective To implement the DVB SH Digital Video Broadcast Satellite Services to Handheld Devices standard designed for transmission of video audio and data services on mobile devices Motivation Mobile TV is expected by many to become one of the next big mass media markets Growing number of mobile phone users around the globe has triggered excessive demand for multimedia content People are constantly on the move and want all the latest updates ranging from news to social life on their fingertips This project is a step towards understanding the process involved in implementing and delivering quality media content to handheld devices What is DVB SH DVB SH 1 is the name of a transmission system standard designed to deliver video audio and data services to vehicles and handheld devices The key feature of DVB SH is that it is a hybrid satellite terrestrial system that allows the use of a satellite to achieve coverage of large regions or even a whole country In areas where direct reception of the satellite signal is not possible a terrestrial gap filler can be used seamlessly to provide coverage It is designed to use frequencies below 3GHz typically around 2 2GHz The system and waveform specifications have been published as ETSI standards TS 102 584 TS 102 585 and EN 302 583 1 System Architecture Figure 1 shows the network architecture of the DVB SH system TR a are broadcast infrastructure transmitters that provide reception in urban areas TR b are personal gap fillers Their purpose is to provide indoor coverage TR c are mobile broadcast infrastructure transmitters OFDM Orthogonal Frequency Division Multiplexing 8 is the natural choice for terrestrial modulation and is the basis of both the DVB H and DVB T systems DVB SH introduces a second scheme a time division multiplex TDM leading to two reference architectures termed SH A and SH B 8 SH A uses OFDM both on the satellite and the terrestrial link SH B uses TDM on the satellite link and OFDM for the terrestrial link Time slicing Time slicing is a very important aspect in DVB H technology The objective of time slicing is to reduce the average power consumption of the terminal and enable smooth and seamless service handover Time slicing consists of sending data in bursts using significantly higher instantaneous bit rate compared to the bit rate required if the data were transmitted using traditional streaming mechanisms 8 Time slicing enables a receiver to stay active only a fraction of the time while receiving bursts of a requested service Note that the transmitter is constantly on i e the transmission of the transport stream is not interrupted Time slicing also supports the possibility to use the receiver to monitor neighboring cells during the off times between bursts By accomplishing the switching of the reception from one transport stream to another during an off period it is possible to accomplish a quasi optimum handover decision as well as seamless service handover Compression in DVB SH DVB SH uses H 264 AVC compression standard The block diagram of H 264 encoder and decoder are given in figure 2 and figure 3 respectively Band used for DVB SH transmission Figure 4 Band used in DVB SH transmission DVB SH seeks to exploit the less congested higher frequency S band where there are opportunities for MSS mobile satellite services systems operating in conjunction with CGC complementary ground components Typical applications of DVB SH may include Broadcasting of radio and TV content Broadcasting of audio or video content customized for mobile TV e g virtual TV channels podcasts Data delivery push e g for ring tones logos Video on demand services Informative services e g news including location based services Interactive services via an external communications channel e g UMTS Universal Mobile Telecommunications System Figure 5 Conceptual description of a DVB SH system 11 Figure 6 Conceptual description of a DVB SH receiver 11 Table 1 gives the frequency domain parameters for the 8 MHz channel For other bandwidths simple scaling offers the parameters where narrowing channel bandwidth means increased symbol length Note that the number of active carriers is smaller than directly proposed by the FFT size As in DVB T this is due to having some guard band with zero amplitude carriers Table 1 Physical layer parameter and data rates of DVB SH system 11 Table 2 gives the OFDM symbol lengths in time domain with and without guard intervals It is worth noting that with the longest guard interval and using 4K mode one can build SFN single frequency network using up to about 33 35 km transmitter distances The maximum distance is dictated by the transmission delay between the transmitter sites This should be smaller than the guard interval length Table 2 Time domain parameters for DVB SH OFDM signal 11 DVB SH systems in the United States The telecom operator AT T has agreed to buy spectrum in the lower 700 MHz frequency band licensed by Qualcomm 12 Alcatel Lucent has hosted successful trials of DVB SH systems across the United States 12 ICO Global Communications has successfully launched a satellite named ICO G1 specifically for mobile television 12 References 1 ETSI EN 301192 Digital Video Broadcasting DVB DVB specification for data broadcasting DVB DATA 2 ETSI TS 102005 Digital Video Broadcasting DVB Specification for the use of video and audio coding in DVB services delivered directly over IP 3 ETSI EN 300468 Digital Video Broadcasting DVB Specification for Service Information SI in DVB systems DVB SI References 1 2 and 3 can be accessed from http www dvb h org 4 DVB BlueBook A079 Rev 1 IP Datacast over DVB H PSI SI http broadcasting ru pdf standard specifications internet 20protocol a079 pdf 5 DVB BlueBook A111 Framing structure channel coding and modulation for Satellite Services to Handheld devices SH below 3GHz http www dvb org RoxenUserID 9b5031601a81d830f6f38d9ed110cb03 technology standards a111 DVBSH Specification pdf 6 DVB Scene edition No 21 A New Star in the Sky by Prof Dr Ing Ulrich Reimers 7 P Kelley C Rigal DVB SH in S band References 6 and 7 can be accessed from http www ebu ch fr technical trev trev 311dvb sh pdf 8 DVB SH fact sheet 0409 April 2009 http www dvb h org PDF dvb sh fact sheet 0409 pdf 9 ETSI EN 302304 V1 1 1 2004 11 Digital
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