OVSF code allocation and two-stage combining method to reduce intercode interference in OFCDM system

Kazuhiko Hasegawa, Ryuichiro Shimura, Iwao Sasase

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

In this paper, we propose an OVSF (Orthogonal Variable Spreading Factor) code allocation in OFCDM (Orthogonal Frequency and Code Division Multiplexing) system. In the proposed OVSF code allocation, codes which have a different ancestor code are allocated to users. When the proposed OVSF code allocation is used, a receiver can use a despreading which utilizes chips shorter than the spreading factor. Thus, symbols are generated. Furthermore, we propose a two-stage combining method. After first stage combining, by despreading, the symbols are multiplied by weights and combined in second stage combining. We show that the proposed scheme achieves better BER performance than the conventional scheme by computer simulations.

Original languageEnglish
Pages (from-to)16-24
Number of pages9
JournalElectronics and Communications in Japan, Part I: Communications (English translation of Denshi Tsushin Gakkai Ronbunshi)
Volume90
Issue number9
DOIs
Publication statusPublished - 2007 Sep

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Multiplexing
Computer simulation

Keywords

  • Intercode interference
  • MMSE combining
  • OFCDM
  • OVSF code

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Computer Networks and Communications

Cite this

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abstract = "In this paper, we propose an OVSF (Orthogonal Variable Spreading Factor) code allocation in OFCDM (Orthogonal Frequency and Code Division Multiplexing) system. In the proposed OVSF code allocation, codes which have a different ancestor code are allocated to users. When the proposed OVSF code allocation is used, a receiver can use a despreading which utilizes chips shorter than the spreading factor. Thus, symbols are generated. Furthermore, we propose a two-stage combining method. After first stage combining, by despreading, the symbols are multiplied by weights and combined in second stage combining. We show that the proposed scheme achieves better BER performance than the conventional scheme by computer simulations.",
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AU - Shimura, Ryuichiro

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AB - In this paper, we propose an OVSF (Orthogonal Variable Spreading Factor) code allocation in OFCDM (Orthogonal Frequency and Code Division Multiplexing) system. In the proposed OVSF code allocation, codes which have a different ancestor code are allocated to users. When the proposed OVSF code allocation is used, a receiver can use a despreading which utilizes chips shorter than the spreading factor. Thus, symbols are generated. Furthermore, we propose a two-stage combining method. After first stage combining, by despreading, the symbols are multiplied by weights and combined in second stage combining. We show that the proposed scheme achieves better BER performance than the conventional scheme by computer simulations.

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