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  • Research Article
  • Open Access

Universal Linear Precoding for NBI-Proof Widely Linear Equalization in MC Systems

EURASIP Journal on Wireless Communications and Networking20072008:321450

  • Received: 1 May 2007
  • Accepted: 1 September 2007
  • Published:


In multicarrier (MC) systems, transmitter redundancy, which is introduced by means of finite-impulse response (FIR) linear precoders, allows for perfect or zero-forcing (ZF) equalization of FIR channels (in the absence of noise). Recently, it has been shown that the noncircular or improper nature of some symbol constellations offers an intrinsic source of redundancy, which can be exploited to design efficient FIR widely-linear (WL) receiving structures for MC systems operating in the presence of narrowband interference (NBI). With regard to both cyclic-prefixed and zero-padded transmission techniques, it is shown in this paper that, with appropriately designed precoders, it is possible to synthesize in both cases WL-ZF universal equalizers, which guarantee perfect symbol recovery for any FIR channel. Furthermore, it is theoretically shown that the intrinsic redundancy of the improper symbol sequence also enables WL-ZF equalization, based on the minimum mean output-energy criterion, with improved NBI suppression capabilities. Finally, results of numerical simulations are presented, which assess the merits of the proposed precoding designs and validate the theoretical analysis carried out.


  • Full Article
  • Symbol Sequence
  • Publisher Note
  • Transmission Technique
  • Linear Equalization

Publisher note

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Authors’ Affiliations

Dipartimento per le Tecnologie, Università Parthenope, Centro Direzionale, isola, C4 I-80143, Italy
Dipartimento di Ingegneria Elettronica e delle Telecomunicazioni, Università Federico II, via Claudio 21, Napoli, I-80125, Italy


© Donatella Darsena et al. 2008

This article is published under license to BioMed Central Ltd. 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.