在光纖展頻通訊中, 若使用質數值為P之修正質數碼做為展頻碼,它的長度為P/sup 2/chips, 但其解碼容量卻只有P/sup 2/個。若需要較大之解碼容量時, 必須使用較大之P值而使得展頻碼可能太長而不切實際。本論文改用由多個質數P/sub 1/、P/sub 2/...P/sub k/之修正質數碼所合併的新碼做為展頻碼, 結果只需(P/sup 2//sub 1/+P/sup 2//sub 2/+Λ+P/sup 2//sub k/) chips之長度即能擁有(P/sup 2//sub 1/×P/sup 2//sub 2/×Λ×P/sup 2//sub k/)之解碼容量, 而且其解碼系統只需沿用原修正質數碼之簡易結構即可。 The Modified Prime Code with prime number P, used in optical spread spectrum systems has the property that both its code length and the number of codes are P/sup 2/. Thus, in a system that needs large capacity of codes, the code length may be too large for practice. In this paper, a new code which combines several modified prime codes, with prime number P/sub 1/P/sub 2/...P/sub k/ respectively, is proposed. It is shown that the new code can be use in the same basically encoding/decoding structure as the modified prime code. Also, it is shown that using only(P/sup 2//sub 1/+P/sup 2//sub 2/+Λ+P /sup 2//sub k/) chip length, the new code can reach the capacity of (P/sup 2//sub 1/×P/sup 2//sub 2/×Λ×P/sup 2//sub k/) codes.
關聯:
一九九八年全國電信研討會論文集=Proceedings of 1998 National Symposium on Telecommunications,頁137-142