• Title/Summary/Keyword: IFDMA

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Multiple Access Interference Cancellation for IFDMA Systems with Frequency Offsets (IFDMA 시스템에서 주파수 옵셋에 의한 다중접속간섭 제거 기법)

  • Kim, Jeong-Woo;Won, Yu-Jun;Seo, Bo-Seok
    • Journal of Satellite, Information and Communications
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    • v.6 no.1
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    • pp.32-36
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    • 2011
  • In this paper, we propose a cancellation scheme of multiple access interference (MAI), which is caused by carrier frequency offset, for the receiver of an interleaved orthogonal frequency division multiple access (IFDMA) uplink system. In the IFDMA systems, carrier frequency offsets introduce adjacent channel interference from other users' subcarriers, which results in performance degradation. In the proposed method, we compensate the carrier frequency offset in time domain and then eliminate MAI by using parallel interference cancellation in frequency domain. Simulation results show that the proposed method is effective in removing the MAI especially when the number of users are large and the MAI severely degrades the system performance.

The Effect of Clipping on the Spectrum and BER of IFDMA Signal with Pulse Shaping (파형정형된 IFDMA 신호에서 클리핑이 스펙트럼과 BER에 미치는 영향)

  • Park, Seung-Yong;Kim, Jeong-Goo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.34 no.11C
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    • pp.1106-1112
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    • 2009
  • The SC-FDMA(single carrier-frequency division multiple access) was recently adopted as the uplink multiple access scheme from 3GPP LTE(3rd Generation Partnership Project Long Tenn Evolution) due to its low PAPR (Peak-to-averaged power ratio). The bandwidth of IFDMA(interleaved FDMA), one of the sub-carrier mapping methods of SC-FDMA, gets narrower as the roll-off factor of RRC(root raised cosine) filter decreases from 1 to 0, whereas its PAPR can increase significantly. In practice, to increase the power efficiency of an amplifier, signals with high PAPR undergo the process of clipping. Clipping of signals may cause regeneration of high-frequency components as well as distortion of signals. The current paper deals with the effect of clipping on the spectrum and BER of IFDMA signals with RRC filters.