### Abstract

Using the notion of expanding subspace and the framework of reduced-rank signal processing, we present our latest discovery on applying the vector and matrix conjugate gradient (CG) methods to design reduced-rank linear MMSE multiuser detectors (MUD) for code division multiple access (CDMA) systems. We show that for a synchronous CDMA system with K users, each using a distinct length N spreading code, the vector CG method converges to the full-rank linear MUD in at most K steps (K ≤ N). The matrix CG method converges to the full-rank linear MUD in one step. Furthermore, when the Gold codes are used as spreading codes in combination with a groupwise power control scheme, early convergence in the vector CG Wiener filter can be reached in just L steps (L ≪ K ≤ N), typically L = 2-4 independent of the user number K and the spreading length N.

Original language | English (US) |
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Pages | 189-193 |

Number of pages | 5 |

State | Published - Dec 1 2004 |

Event | 2004 IEEE 5th Workshop on Signal Processing Advances in Wireless Communications, SPAWC - Lisbon, Portugal Duration: Jul 11 2004 → Jul 14 2004 |

### Other

Other | 2004 IEEE 5th Workshop on Signal Processing Advances in Wireless Communications, SPAWC |
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Country | Portugal |

City | Lisbon |

Period | 7/11/04 → 7/14/04 |

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### All Science Journal Classification (ASJC) codes

- Engineering(all)
- Signal Processing

### Cite this

*Reduced-rank multiuser detectors based on vector and matrix conjugate gradient Wiener filters*. 189-193. Paper presented at 2004 IEEE 5th Workshop on Signal Processing Advances in Wireless Communications, SPAWC, Lisbon, Portugal.