BibTeX
@MISC{Steendam_designand,
author = {Heidi Steendam},
title = {DESIGN AND ANALYSIS OF THE UW-OFDM SIGNAL},
year = {}
}
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Abstract
Unique word (UW-) OFDM is a novel multicarrier system that is shown to be suitable for cognitive radio systems. To construct the UW-OFDM signal, a code generation matrix is required to introduce redundancy in the frequency domain, implying that the code generation matrix must satisfy a num-ber of conditions. In this paper, we use an algebraic construc-tion method to separate the conditions imposed by the signal shape from the code design. The degrees of freedom resulting from this construction method are used to optimize different performance measures (i.e., the minimum Euclidean distance and the power) at the transmitter or at the receiver side. Based on the algebraic decomposition, a composite channel can be defined. Irrespective of whether the optimization is done at the transmitter or the receiver, we shown in the paper that al-ways the strongest modes of this composite channel must be excited. Index Terms — multicarrier communication, error rate, Euclidean distance, tight frame 1. UW-OFDM In multicarrier communication systems, typically a guard in-terval is used to combat the effect of intersymbol interference. In traditional multicarrier systems, this guard interval is added on top of the signal containing the data, resulting in a signal with extended symbol duration. Unlike these standard multi-carrier systems, unique word (UW-) OFDM counteracts inter-symbol interference without the necessity to extend the DFT block with a guard interval. In UW-OFDM, this guard inter-val is part of the DFT interval, i.e., the last Nu samples of the DFT interval are reserved for the unique word, which is a se-quence of known samples. In [1], it is shown that UW-OFDM outperforms cyclic prefix (CP-) OFDM with respect to the bit error rate in fading channels. This is confirmed in [2] where a theoretical analysis of the error rate performance shows that UW-OFDM is always able to achieve full diversity, whereas in CP-OFDM only a diversity one is obtained unless precod-ing is used. Further, it is shown in [3] that UW-OFDM has
Keyphrases
uw-ofdm signal unique word code generation matrix composite channel guard interval dft interval last nu sample intersymbol interference construction method frequency domain error rate performance signal shape index term different performance measure known sample inter-symbol interference extended symbol duration tight frame guard inter-val full diversity euclidean distance code design receiver side cognitive radio system traditional multicarrier system algebraic decomposition minimum euclidean distance error rate dft block standard multi-carrier system bit error rate communication system uw-ofdm outperforms cyclic prefix algebraic construc-tion method novel multicarrier system guard in-terval theoretical analysis
