### Abstract

The adaptive parallel subgradient projection (PSP) algorithm was proposed in 2002 as a set-theoretic adaptive filtering algorithm providing fast and stable convergence, robustness against noise, and low computational complexity by using weighted parallel projections onto multiple time-varying closed half-spaces. In this paper, we present a novel weighting technique named pairwise optimal weight realization (POWER) for further acceleration of the adaptive PSP algorithm. A simple closed-form formula is derived to compute the projection onto the intersection of two closed half-spaces defined by a triplet of vectors. Using the formula inductively, the proposed weighting technique realizes a good direction of update. The resulting weights turn out to be pairwise optimal in a certain sense. The proposed algorithm has the inherently parallel structure composed of q primitive functions, hence its total computational complexity O(_{qr}N) is reduced to O(rN) with q concurrent processors (r: a constant positive integer). Numerical examples demonstrate that the proposed technique for r =1 yields significantly faster convergence than not only adaptive PSP with uniform weights, affine projection algorithm, and fast Newton transversal filters but also the regularized recursive least squares algorithm.

Original language | English |
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Pages (from-to) | 4557-4571 |

Number of pages | 15 |

Journal | IEEE Transactions on Signal Processing |

Volume | 54 |

Issue number | 12 |

DOIs | |

Publication status | Published - 2006 Dec 1 |

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### Keywords

- Adaptive parallel subgradient projection
- Optimal weight design
- Set-theoretic adaptive filtering

### ASJC Scopus subject areas

- Signal Processing
- Electrical and Electronic Engineering