Blind Decoding of Multiple Description Codes over OFDM Systems via Sequential Monte Carlo
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Blind Decoding of Multiple Description Codes over OFDM Systems via Sequential Monte Carlo Zigang Yang Texas Instruments Inc, 12500 TI Boulevard Dallas, MS 8653 Dallas, TX 75243, USA Email: [email protected]
Dong Guo Department of Electrical Engineering, Columbia University, New York, NY 10027, USA Email: [email protected]
Xiaodong Wang Department of Electrical Engineering, Columbia University, New York, NY 10027, USA Email: [email protected] Received 1 May 2004; Revised 20 December 2004 We consider the problem of transmitting a continuous source through an OFDM system. Multiple description scalar quantization (MDSQ) is applied to the source signal, resulting in two correlated source descriptions. The two descriptions are then OFDM modulated and transmitted through two parallel frequency-selective fading channels. At the receiver, a blind turbo receiver is developed for joint OFDM demodulation and MDSQ decoding. Transformation of the extrinsic information of the two descriptions are exchanged between each other to improve system performance. A blind soft-input soft-output OFDM detector is developed, which is based on the techniques of importance sampling and resampling. Such a detector is capable of exchanging the so-called extrinsic information with the other component in the above turbo receiver, and successively improving the overall receiver performance. Finally, we also treat channel-coded systems, and a novel blind turbo receiver is developed for joint demodulation, channel decoding, and MDSQ source decoding. Keywords and phrases: multiple description codes, OFDM, frequency-selective fading, sequential Monte Carlo, turbo receiver.
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INTRODUCTION
Multiple description scalar quantization (MDSQ) is a source coding technique that can exploit diversity communication systems to overcome channel impairments. An MDSQ encoder generates multiple descriptions for a source and sends them over different channels provided by the diversity systems. At the receiver, when all descriptions are received correctly, a high-quality reconstruction is possible. In the event of failure of one or more of the channels, the reconstruction would still be of acceptable quality. The problem of designing multiple description scalar quantizers is addressed in [1, 2], where a theoretical performance bound is derived in [1] and practical design methods are given in [2, 3]. Conventionally, MDSQ has been This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
investigated only from the perspective of transmission over erasure channels, that is, channels which either transmit noiselessly or fail completely [1, 2, 4]. Recently, it was shown in [5] that an MDSQ can be used effectively for communication over slow-fading channels. In that system, a threshold on the channel fade values is used to determine the acceptability of the received description. The signal received from the bad co
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