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Träfflista för sökning "WFRF:(Agrell Erik 1965 ) srt2:(2005-2009)"

Sökning: WFRF:(Agrell Erik 1965 ) > (2005-2009)

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21.
  • Zhao, Hongxia, 1971, et al. (författare)
  • Trellis-Coded Modulation in PSK and DPSK Communications
  • 2006
  • Ingår i: European Conference on Optical Communication. - 9782912328397 ; , s. 1-2
  • Konferensbidrag (refereegranskat)abstract
    • Coded modulation is for the first time investigated in phase-modulated systems, with coherent as well as differential detection. We find coding gains of 3.0 and 1.7 dB, already with the simplest possible trellis code.
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22.
  • Zhao, Hongxia, 1971, et al. (författare)
  • Unequal bit error probability in coherent QPSK fiber-optic systems using phase modulator based transmitters
  • 2008
  • Ingår i: European Transactions on Telecommunications. - : Wiley. - 1541-8251 .- 1124-318X. ; 19:8, s. 895-906
  • Tidskriftsartikel (refereegranskat)abstract
    • We report on the occurrence of unequal bit error probability in a coherent quadrature phase shift keying (QPSK) fiber optic system. The bit error rates (BER) of two QPSK bits are derived individually based on the developed system model, and they turn out to differ by more than an order of magnitude for a phase modulator based transmitter. The phenomenon, previously unreported, arises because such a transmitter introduces a controlled form of inter-symbol-interference (ISI), and the receiver low-pass filters affect this ISI differently for the two bits. The optimum bandwidth of the receiver low-pass filter is obtained from the analytic derivation, which is about 0.7 times the symbol rate. We propose two simple system modifications, one in the transmitter and one in the receiver, to compensate for the phenomenon and equalize the two BER's. Those modifications improve the system performance by about 2~dB without adding any extra hardware.
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  • Resultat 21-22 av 22

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