前沿课题讲座05手机电视.pptVIP

手机电视 孙松林 北京邮电大学 Email: slsun@ Mobile: Content DVB-H Digital Video Broadcasting for Handheld UMTS-PSS Universal Mobile Telecommunications System Packet Switched Stream Introduction Convergence of digital media and communication give users possibility to consume most digital content also in mobile environment The emerging DVB-H standard aims to provide digital TV reception in mobile devices Earlier known as DVB-X DVB-H is being standardized by and ad hoc group of the DVB organization Expected to be standardized in the first quarter of 2004 DVB-H combines traditional television broadcast standards with elements specific to handheld devices; mobility, smaller screens and antennas, indoor coverage and reliance on battery power? Motivation for creating DVB-H Why not use UMTS? Not scalable for mass content delivery For delivery of mass media content, broadcast networks should be preferred over point-to-point cellular networks Why not use DVB-T? Was designed for rooftop reception Need for an efficient power saving mechanism Inadequate impulse noise protection Why not use DAB? Designed for devices with similar power constraints but too narrow spectrum is assigned for data transmission 四种不同的典型导频分布图 DVB-T系统中的导频插入方案 DVB-T的帧结构 DVB-T Terrestrial Digital Television Standard Used in 36 countries world wide One-to-many broadband wireless data transport Video, audio, data and – importantly – IP packets Scalable: cell size up to 100km (DVB-H cell size is smaller) Huge capacity: 54 channels each 5-32Mbit/s Shut down of analog TV will free up huge frequency capacity for DVB-T usage DVB-T (cont.) Developed for MPEG-2 stream distribution, but can basically carry any data Flexible, has many modes, 4.98-31.67 Mbit/s @ C/N=25dB COFDM multicarrier modulation with 2k and 8k modes One DVB channel is ~8MHz 1705 sub carriers (spacing: 4464 Hz) - 2k mode 6817 sub carriers (spacing: 1116 Hz) - 8k mode Carrier modulation: QPSK, 16 QAM or 64 QAM Error correction: convolutional code