OFDM: An Old Idea solves New Problems

Autoren: K.-D. Kammeyer, H. Schmidt
Kurzfassung: The multicarrier technique is known since more than 40 years. First practical applications, however, were not considered before 1990 when Bingham’s famous paper appeared which pointed out the great attraction of this idea – especially in the form of the FFT-based ”OFDM” (Orthogonal Frequency Division Multiplexing). Meanwhile, OFDM is applied in the DAB and DVB standard (Digital Audio/Video Broadcasting) and in modern indoor communication concepts like HIPERLAN/2 and IEEE802.11a. In this paper an overview of new techniques in the field of multicarrier transmission will be given. At first, the attention is focused on the problems of equalization and channel estimation. Noise reduction methods are applied which exploit the fact that the channel impulse response is shorter than the FFT length used. A quite modern concept is the so-called ”turbo estimation” where channel decoding can be included in the estimation process. This leads to a very powerful channel tracking algorithm. In some recent papers OFDM was compared to the classical single carrier structure with a frequency domain equalizer; here it will shown that OFDM outperforms the single carrier structure if channel coding is taken into account. The performance of the algorithms developed here is demonstrated by simulation results based on the HIPERLAN/2 Standard.
Dokumenttyp: Konferenzbeitrag
Veröffentlichung: Linz, Austria, 19. - 22. August 2001
Konferenz: International Symposium on Theoretical Electrical Engineering (ISTET 01)
Index: 190
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