An interference-avoidance code assignment strategy for the hierarchical two-dimensional-spread MC-DS-CDMA system: A prototype of cognitive radio femtocell system

研究成果: Article同行評審

32 引文 斯高帕斯(Scopus)

摘要

In recent years, the family of multicarrier code-division multiple-access (MC-CDMA) transmission technologies has drawn a lot of attention in providing broadband wireless communication services. From the literature, one can find extensive discussions in many aspects of MC-CDMA under a flat system architecture either for conventional or currently emerging cognitive radio (CR) systems. In this paper, we shift the focus from the flat architecture to the hierarchical architecture based on 2-D-spread multicarrier direct-sequenced CDMA, in which a microcell is embedded in the primitive macrocell. However, in such a hierarchical architecture, severe intercell interference can occur between the macrocell and the microcell. Via the interference avoidance code assignment strategy, this kind of intercell interference in downlink transmissions can be eliminated. To this end, we define the white, gray, and black spreading codes to facilitate the management of spreading code resources. Properly allocating the white and gray spreading codes but the black ones can achieve a higher spectrum efficiency without harming the macrocell users. For the purpose of evaluating the candidacy of the gray spreading codes, a sophisticated interference analysis is conducted to define a new multiple access interference (MAI) coefficient to quantize the amount of interference imposed on a microcell user. With the help of the new MAI coefficient, a less-interfered white or gray spreading code can be assigned to microcell users, which can bring about an extra 55% of call admissions in one of our considered cases. Moreover, the capability of the proposed hierarchical system architecture, as well as the interference management scheme for developing the femtocell system, has also been proved via simulation results with a large number of femtocells. It is believed that by cooperating with the substream deactivation technique, the proposed spreading code management associated with the hierarchical system architecture can be a potential prototype of the CR-based femtocell system.

原文English
文章編號6062426
頁(從 - 到)166-184
頁數19
期刊IEEE Transactions on Vehicular Technology
61
發行號1
DOIs
出版狀態Published - 2012 一月

All Science Journal Classification (ASJC) codes

  • Automotive Engineering
  • Aerospace Engineering
  • Electrical and Electronic Engineering
  • Applied Mathematics

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