The problem of the peak to average power ratio (PAPR) is more prominent in non-continuous orthogonal frequency division multiplexing (NC-OFDM) modulation than in orthogonal frequency division multiplexing (OFDM) modulation. To study the influence of subcarrier distribution on PAPR, we defined the autocorrelation function R(ε) within a symbol period and the inter-symbol autocorrelation coefficient ρ(ε), which was used to measure the relationship between the PAPR, the total number of subcarriers,

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... and the number of cognitive users. Only when the total number of subcarriers was constant, the number of cognitive users was the main factor affecting PAPR; when the total number of subcarriers and the number of cognitive users were constant, the values of the autocorrelation coefficient varied with the distribution scheme where at this time, the statistical probability of PAPR increases monotonically with the increase of the autocorrelation coefficient. Using the appropriate subcarrier allocation scheme, which has a low autocorrelation coefficient, the PAPR of the NC-OFDM modulated signal could be effectively reduced by 5% to 6%.