Equalization methods in OFDM and FMT systems for broadband wireless communications

Multicarrier systems are adopted in several standards for their ability to achieve optimal performance in very dispersive channels. In particular, orthogonal-frequency division multiplexing (OFDM) and filtered multitone (FMT) systems are two examples where the modulation filter has an ideal rectangu...

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Bibliographic Details
Published in:IEEE transactions on communications 2002-09, Vol.50 (9), p.1413-1418
Main Authors: Benvenuto, N., Tomasin, S., Tomba, L.
Format: Article
Language:English
Subjects:
Amplitude modulation
Bit error rate
Bit rate
Broadband
Broadband communication
Channels
Dispersion
Equalization
Equalizers
Fading
Filters
Frequency domain analysis
Modulation
OFDM modulation
Orthogonal Frequency Division Multiplexing
Studies
Wireless communication
Wireless communications
Wireless networks
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Summary:Multicarrier systems are adopted in several standards for their ability to achieve optimal performance in very dispersive channels. In particular, orthogonal-frequency division multiplexing (OFDM) and filtered multitone (FMT) systems are two examples where the modulation filter has an ideal rectangular amplitude characteristic in time and frequency domains, respectively. In this letter, we propose new equalization schemes for FMT and compare their performances with OFDM. In general, FMT has a greater spectral efficiency than OFDM, due to the absence of the cyclic prefix and a reduced number of virtual carriers. However, it exhibits a higher distortion per subchannel, due to the imperfect equalization of the transmit filters. As a performance comparison, we considered both the achievable bit rate (ABR) and the bit error rate (BER) in a multipath Rayleigh fading channel. We note that while ABR gives a theoretical bound on the system bit rate, assuming the knowledge of the channel at the transmit side, the BER refers to an uncoiled system with a fixed modulation. Although FMT requires a fixed structure with a higher computational complexity than OFDM, it turns out that FMT, even with the simplest one tap per subchannel adaptive equalizer, yields a better performance than OFDM, both in terms of ABR and BER. Hence, FMT can be a valid alternative to OFDM for broadband wireless applications, also.
ISSN:0090-6778
1558-0857
DOI:10.1109/TCOMM.2002.802571