8 December 1995 Orthogonal frequency division multiplexing with coding and transmitter antenna diversity
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Proceedings Volume 2601, Wireless Data Transmission; (1995); doi: 10.1117/12.228138
Event: Photonics East '95, 1995, Philadelphia, PA, United States
Abstract
In this paper we consider transmitter diversity for a OFDM system. In a OFDM system, each of the sub-carriers experience a different fade, and depending on the coherence band-width, several adjacent sub-carriers may be in a deep fade. If the channel is also varying slowly, these sub-carriers will be in a fade for a long time. To avoid the waste of band-width and errors on the affected sub-carriers, transmitter diversity can be used with the OFDM system so that the sub-carriers over the 'bad' part of the spectrum can still be utilized. OFDM systems which use FFT based demodulation at the receiver are especially unsuitable for Doppler and delay spread channels. In such channels OFDM system performance degrades due to the loss in orthogonality of the sub-carriers and the consequential increase in inter-carrier interference (ICI). Hence, we conclude that an FFT based receiver is not suitable for wireless channels, and we propose the use of multiple demodulators at the receiver, each operating over an individual sub-carrier band. This increases the complexity, however, such an increase is necessary for a wireless channel. In this paper we show how the full band-width available to the system can be utilized using multiple transmitting antennas.
© (1995) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Zulfiquar Sayeed, Saleem A. Kassam, "Orthogonal frequency division multiplexing with coding and transmitter antenna diversity", Proc. SPIE 2601, Wireless Data Transmission, (8 December 1995); doi: 10.1117/12.228138; http://dx.doi.org/10.1117/12.228138
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KEYWORDS
Antennas

Orthogonal frequency division multiplexing

Receivers

Transmitters

Doppler effect

Demodulation

Signal to noise ratio

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