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008			230300s1999 th u m rtt 0| a1eng d
035			_a.b11782791
099		9	_aAIT Thesis no.TC-99-4
100	0		_aTran Anh Tuan
245	1	0	_aUnequal error protection for MPEG-2 video transmission over frequency selective Rayleigh fading channels
260			_aBangkok : _bAsian Institute of Technology, _c1999
300			_a81 p.
490	1		_aThesis ; _vno. TC-99-4
500			_aA thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering. School of Advanced Technologies
502			_aThesis (M.Eng.) - Asian Institute of Technology, 1999
520			_aMPEG-2 video communication over wireless challilels has been rece1vmg a lot of attention recently. MPEG-2 video is, however, extremely sensitive, due to the compression techniques it employs, to transmission errors. One single bit error may dramatically degrade the quality of the reconstructed video. Forward error correction (FEC) may be used to protect the transmitted video sequence. The sensitivity of different bits in the sequence, to transmission errors, however, varies from bit to bit. Unequal error protection (UEP) is therefore more beneficial than equal error protection (EEP). Furthermore, frequency-selective wireless challilels exhibit different fading levels over a period. The error correction assignments should also vary adaptively with the transmission conditions. In this thesis, the effects of bit errors at different positions in the video sequence were investigated. Results of the investigation show that the degree of importance of the bits in each slice varies from bit to bit. The bits at the begilliling of each slice are far more important than those bits at the far end of the slice. Therefore, the bits in each slice should be provided with different error control levels in order to improve video quality while minimizing the overhead due to FEC. A new UEP scheme was proposed, based on the above investigation results, which can improve the video quality of MPEG-2 video, transmitted over frequency selective RC1 yleigh fading challilels, without bandwidth expansion. In this scheme, not only header and control info1mation is provided with higher error control level, but also the video data in each slice is unequally protected. Here, an MPEG-2 video sequence is first split into different layers according to their importance. In each layer, the header and control information is separated and protected by higher error protection level. The video data in each slice is also unequally protected according to the position of the data in the slice. Rate-compatible punctur ~d convolutional codes, obtained by puncturing a (3,1,6) convolutional code, are used to provide UEP for the video sequence. The simulation results (using different video sequences) show remarkable improvement in both objective (up to 4 dB improvement in peak signal to noise ratio was observed) and subjective video quality compared to the video quality that was transmitted under the EEP scheme. Furthermore, the proposed scheme yields the same, or even slightly less, amount of overhead, due to FEC, compared to the EEP scheme. It was further noted that if the challilel state information is available at the transmitter, different error correction assignments could be applied adaptively with the challilel state information, which may give better results. It can, based on the above results, be concluded that the proposed scheme is a robust scheme to transmit MPEG-2 video over wireless challilels under a bandwidth constraint.
650		0	_aDigital communications
700	1		_aRajatheva, R.M.A.P, _eChairperson
700	1		_aAhmed, Kazi Mohiuddin, _eExamination Committee
700	0		_aTeerapat Sanguankotchakorn, _eExamination Committee
710	2		_aNokia Telecommunications, _eScholarship donor
810	2		_aAsian Institute of Technology. _tThesis ; _vno. TC-99-4
856			_3Full-Text _uhttp://203.159.5.9/ait-thesis/detail.php?q=B12250
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