| 摘要 |
PROBLEM TO BE SOLVED: To avoid interference between carriers by detecting the speed of a vehicle within a cell, and the higher the detected speed is the more spread the frequency interval of the subcarrier of orthogonal frequency division multiplex(OFDM) is set. SOLUTION: Concerning OFDM, when a transmission rate per subcarrier is defined as R (kbps) and the frequency interval between subcarriers is defined asΔF, the relationΔF=K.R (K is an integer and expressed as 'carrier arrangement K' hereafter) must be established. In normal OFDM, the condition of subcarrier arrangement K=1 is established. Since Doppler deviation with traveling is made large when traveling the vehicle, if subcarrier arrangement K=1 is assumed a carrier interference is generated by the influence of frequency fluctuation of the subcarrier. Therefore, the carrier arrangement K is increased to '2' or '3', for example, as shown in figure (b) or (c), and the influence of the Dopper deviation is avoided. Thus, even if the frequency of the subcarrier fluctuates somewhat, the carrier interference will not be generated.
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