Multichannel fast QR-decomposition algorithms: Weight extraction method and its applications

Mobien Shoaib*, Stefan Werner, José Antonio Apolinário

*Corresponding author for this work

    Research output: Contribution to journalArticleScientificpeer-review

    7 Citations (Scopus)


    Multichannel fast QR decomposition RLS (MCFQRD- RLS) algorithms are well known for their good numerical properties and low computational complexity. The main limitation is that they lack an explicit weight vector term, limiting themselves to problems seeking an estimate of the output error signal. This paper presents techniques which allow us to use MC-FQRD-RLS algorithms with applications that previously have required explicit knowledge of the adaptive filter weights. We first consider a multichannel system identification setup and present how to obtain, at any time, the filter weights associated with the MC-FQRD-RLS algorithm. Thereafter, we turn to problems where the filter weights are periodically updated using training data, and then used for fixed filtering of a useful data sequence, e.g., burst-trained equalizers. Finally, we consider a particular control structure, indirect learning, where a copy of the coefficient vector is filtering a different input sequence than that of the adaptive filter. Simulations are carried out for Volterra system identification, decision feedback equalization, and adaptive predistortionof high-power amplifiers. The results verify our claimsthat the proposed techniques achieve the same performance as the inverse QRD-RLS algorithm at a much lower computational cost.

    Original languageEnglish
    Article number5208327
    Pages (from-to)175-188
    Number of pages14
    JournalIEEE Transactions on Signal Processing
    Issue number1
    Publication statusPublished - 1 Jan 2010
    MoE publication typeA1 Journal article-refereed


    • Adaptive systems
    • Equalizer
    • Fast algorithms
    • Indirect learning
    • Multichannel algorithms
    • Predistortion
    • QR decomposition
    • Volterra system identification
    • Weight extraction


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