### Abstract

Multiple-access interference (MAI) depends on chip pulse shapes in chip-asynchronous direct sequence/code division multiple access (DS/CDMA) systems. The mean squared MAI averaged over relative time delays is expressed in a quadratic form, where a coefficient matrix is derived from the pulse shapes, while a variable vector consists of aperiodic autocorrelation functions of the signature sequences. This quadratic form gives a lower bound of the mean squared MAI, which is equivalent to the Welch bound if the pulse shape is a delta function. For any continuous pulse shapes, however, the mean squared MAI is shown to be reduced beyond the Welch bound. In case of rectangular pulse, the mean squared MAI is reduced by 13.4%, whereas the reduction ratio is 5.2% for band-limited pulses with excess bandwidth 0.5.

Original language | English |
---|---|

Title of host publication | Proceedings - 2006 IEEE International Symposium on Information Theory, ISIT 2006 |

Pages | 1524-1528 |

Number of pages | 5 |

DOIs | |

Publication status | Published - Dec 1 2006 |

Event | 2006 IEEE International Symposium on Information Theory, ISIT 2006 - Seattle, WA, United States Duration: Jul 9 2006 → Jul 14 2006 |

### Publication series

Name | IEEE International Symposium on Information Theory - Proceedings |
---|---|

ISSN (Print) | 2157-8101 |

### Other

Other | 2006 IEEE International Symposium on Information Theory, ISIT 2006 |
---|---|

Country | United States |

City | Seattle, WA |

Period | 7/9/06 → 7/14/06 |

### All Science Journal Classification (ASJC) codes

- Theoretical Computer Science
- Information Systems
- Modelling and Simulation
- Applied Mathematics

## Fingerprint Dive into the research topics of 'A lower bound on the mean squared correlations for band-limited asynchronous DS/CDMA systems'. Together they form a unique fingerprint.

## Cite this

*Proceedings - 2006 IEEE International Symposium on Information Theory, ISIT 2006*(pp. 1524-1528). [4036222] (IEEE International Symposium on Information Theory - Proceedings). https://doi.org/10.1109/ISIT.2006.262123