Reverse-link capacity and transmit power in a power-controlled cellular DS-CDMA system

Koji Ohno, Fumiyuki Adachi

Research output: Contribution to journalArticlepeer-review

Abstract

This paper considers the DS-CDMA with an imperfect transmit power control and analyzes the relationship between the reverse-link capacity and the average transmit power, considering the space/path (RAKE) diversity. A simple formula for calculation is derived. Using the space diversity, an instantaneous large transmit power can be avoided when the transmit power is controlled. It is shown that, at that time, the interference from other cells can be reduced and the reverse-link capacity can be increased. Especially, when the spreading bandwidth is narrow and the single-path reception is used, the space diversity is shown to be necessary. It is known in CDMA that the link capacity can be increased by sectorizing the cell. In the practical antenna, however, where the directivity of the antenna overlaps with other sectors, there can be interference from adjacent sectors. A calculation formula is derived considering the antenna directivity. Using that formula, the reverse-link capacity and the average transmit power are examined precisely for the case where the pilot symbol interpolation QPSK coherent detection is used in the data modulation/demodulation. Finally, the effect of the shadowing correlation is investigated.

Original languageEnglish
Pages (from-to)72-82
Number of pages11
JournalElectronics and Communications in Japan, Part I: Communications (English translation of Denshi Tsushin Gakkai Ronbunshi)
Volume80
Issue number4
DOIs
Publication statusPublished - 1997 Apr

Keywords

  • DS-CDMA
  • RAKE reception
  • Space diversity

ASJC Scopus subject areas

  • Computer Networks and Communications
  • Electrical and Electronic Engineering

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