Cognitive interference-minimizing code assignment for underlay CDMA networks in asynchronous multipath fading channels

Ayman Elezabi, Mohamed Kashef, Mohamed Abdallah, Mohamed M. Khairy

Research output: Chapter in Book/Report/Conference proceedingConference contribution

9 Citations (Scopus)

Abstract

We propose a secondary CDMA network that operates as an underlay for a primary CDMA network where the code assignment for the secondary network is done cognitively. A code assignment criterion that minimizes interference from primary users and existing secondary users is formulated. The primary user codes as well as bit boundaries are unknown to the secondary network. The problem is initially formulated as a constrained optimization problem. Exhaustive search has complexity that is exponential in the spreading factor. The constraints are therefore relaxed to obtain a near-optimal solution with a complexity that is linear in the spreading factor and performance very close to the exhaustive search method. We consider the different cases where the primary users are bit- and chip-synchronous, chipsynchronous but bit-asynchronous, and chip-asynchronous over multi-path fading channels. We propose a method for blind epoch acquisition by processing the covariance matrix of the received signal. In all cases the performance improvement of the interference-minimizing code assignment over random code assignment is significant reaching over 3 dB for coded systems.

Original languageEnglish
Title of host publicationProceedings of the 2009 ACM International Wireless Communications and Mobile Computing Conference, IWCMC 2009
Pages1279-1283
Number of pages5
DOIs
Publication statusPublished - 2009
Externally publishedYes
Event2009 ACM International Wireless Communications and Mobile Computing Conference, IWCMC 2009 - Leipzig, Germany
Duration: 21 Jun 200924 Jun 2009

Other

Other2009 ACM International Wireless Communications and Mobile Computing Conference, IWCMC 2009
CountryGermany
CityLeipzig
Period21/6/0924/6/09

Fingerprint

Multipath fading
Fading channels
Code division multiple access
Constrained optimization
Covariance matrix
Processing

Keywords

  • Blind epoch acquisition
  • Cognitive radio
  • Interference mitigation
  • Underlay CDMA networks

ASJC Scopus subject areas

  • Computer Networks and Communications
  • Computer Science Applications
  • Software

Cite this

Elezabi, A., Kashef, M., Abdallah, M., & Khairy, M. M. (2009). Cognitive interference-minimizing code assignment for underlay CDMA networks in asynchronous multipath fading channels. In Proceedings of the 2009 ACM International Wireless Communications and Mobile Computing Conference, IWCMC 2009 (pp. 1279-1283) https://doi.org/10.1145/1582379.1582659

Cognitive interference-minimizing code assignment for underlay CDMA networks in asynchronous multipath fading channels. / Elezabi, Ayman; Kashef, Mohamed; Abdallah, Mohamed; Khairy, Mohamed M.

Proceedings of the 2009 ACM International Wireless Communications and Mobile Computing Conference, IWCMC 2009. 2009. p. 1279-1283.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Elezabi, A, Kashef, M, Abdallah, M & Khairy, MM 2009, Cognitive interference-minimizing code assignment for underlay CDMA networks in asynchronous multipath fading channels. in Proceedings of the 2009 ACM International Wireless Communications and Mobile Computing Conference, IWCMC 2009. pp. 1279-1283, 2009 ACM International Wireless Communications and Mobile Computing Conference, IWCMC 2009, Leipzig, Germany, 21/6/09. https://doi.org/10.1145/1582379.1582659
Elezabi A, Kashef M, Abdallah M, Khairy MM. Cognitive interference-minimizing code assignment for underlay CDMA networks in asynchronous multipath fading channels. In Proceedings of the 2009 ACM International Wireless Communications and Mobile Computing Conference, IWCMC 2009. 2009. p. 1279-1283 https://doi.org/10.1145/1582379.1582659
Elezabi, Ayman ; Kashef, Mohamed ; Abdallah, Mohamed ; Khairy, Mohamed M. / Cognitive interference-minimizing code assignment for underlay CDMA networks in asynchronous multipath fading channels. Proceedings of the 2009 ACM International Wireless Communications and Mobile Computing Conference, IWCMC 2009. 2009. pp. 1279-1283
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