C06-Broadcast_Systems - Prof. Dr.-Ing. JochenSchiller,

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Unformatted text preview: Prof. Dr.-Ing. JochenSchiller, http://www.jochenschiller.de/ MC SS02 6.1 Mobile Communications Chapter 6: Broadcast Systems ¡ Unidirectional distribution systems ¡ DAB ¡ architecture ¡ DVB ¡ Container ¡ High-speed Internet Prof. Dr.-Ing. JochenSchiller, http://www.jochenschiller.de/ MC SS02 6.2 Unidirectional distribution systems Asymmetric communication environments ¡ bandwidth limitations of the transmission medium ¡ depends on applications, type of information ¡ examples z wireless networks with base station and mobile terminals z client-server environments (diskless terminal) z cable TV with set-top box z information services (pager, SMS) Special case: unidirectional distribution systems ¡ high bandwidth from server to client (downstream), but no bandwidth vice versa (upstream) ¡ problems of unidirectional broadcast systems z a sender can optimize transmitted information only for one groupof users/terminals z functions needed to individualize personal requirements/applications Prof. Dr.-Ing. JochenSchiller, http://www.jochenschiller.de/ MC SS02 6.3 Unidirectional distribution service provider service user sender receiver receiver receiver . . . unidirectional distribution medium A A A A A A A B B B B optimized for expected access pattern of all users individual access pattern of one user ≠ Prof. Dr.-Ing. JochenSchiller, http://www.jochenschiller.de/ MC SS02 6.4 Sender ¡ cyclic repetition of data blocks ¡ different patterns possible (optimization possible only if the content is known) Receiver ¡ use of caching z cost-based strategy: what are the costs for a user (waiting time) if a data block has been requested but is currently not cached z application and cache have to know content of data blocks and access patterns of user to optimize Structuring transmissions -broadcast disks A B C A B C flatdisk A A B C A A skeweddisk A B A C A B multi-disk Prof. Dr.-Ing. JochenSchiller, http://www.jochenschiller.de/ MC SS02 6.5 DAB: Digital Audio Broadcasting ¡ Media access ¡ COFDM (Coded Orthogonal Frequency Division Multiplex) ¡ SFN (Single Frequency Network) ¡ 192 to 1536 subcarrierswithin a 1.5 MHz frequency band ¡ Frequencies ¡ first phase: one out of 32 frequency blocks for terrestrial TV channels 5 to 12 (174 -230 MHz, 5A -12D) ¡ second phase: one out of 9 frequency blocks in the L-band (1452-1467.5 MHz, LA -LI) ¡ Sending power: 6.1 kW (VHF, Ø 120 km) or 4 kW (L-band, Ø 30 km) ¡ Date-rates: 2.304 Mbit/s (net 1.2 to 1.536 Mbit/s) ¡ Modulation: Differential 4-phase modulation (D-QPSK) ¡ Audio channels per frequency block: typ. 6, max. 192 kbit/s ¡ Digital services: 0.6 -16 kbit/s (PAD), 24 kbit/s (NPAD) Prof. Dr.-Ing. JochenSchiller, http://www.jochenschiller.de/Prof....
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This note was uploaded on 02/28/2008 for the course CSCI 6360 taught by Professor Wu during the Spring '08 term at University of Texas at Dallas, Richardson.

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C06-Broadcast_Systems - Prof. Dr.-Ing. JochenSchiller,

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