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標題: 跳頻分碼多工無線系統中之 廣義跳頻碼之設計與分析
Design and Performance Analysis of Generalized Hopping Codes for FH-CDMA Wireless Systems
作者: 謝杰紘
Hsieh, Chieh-Hung
關鍵字: FH-CDMA;跳頻分碼多工;Wireless System;無線系統
出版社: 通訊工程研究所
跳頻分碼多工系統在無線通訊上的應用日益受到重視,在本論文中,我們提出一種藉著將最大相關性函數值提升到n,使得碼數目得以變多的新式質數碼,稱之為多階層質數碼。當P是一個質數而代表此質數之次方的n是一正整數,我們可得到碼之數目為P的n次方,這些碼之長度為P且最大相關函數值為n。在碼的長度不變,互相關函數性質變為n的情況下,可大幅提高碼的用戶量,並使其在頻寬不變的狀態下,大量增加同時使用系統之用戶的數目。此多階層質數碼可分為n的階層,如任意兩個碼在第l階層,則其相關函式值即為l。我們分析多階層質數碼在開關鍵移跳頻分碼多工系統中之效能。以往只能求得最大互相關函數值為2之碰撞機率,我們提供了最大互相關函數值為n中互相關函數值為n,n - 1,…,1。之碰撞機率可根據不同的需求,在系統效能與資料傳輸速率上選擇較佳的折衷解決辦法。我們的結果顯示在使用者數量與系統效能中,藉著階層的選擇取得有效的平衡。

The application of frequency-hopping code-division multiple access (FH-CDMA) to wireless communication systems has been receiving significant attention recently. In this thesis, we study a new family of prime codes, so-called multi-level prime codes, with ex-panded code cardinality by relaxing the maximum cross-correlation function of λc to n, where n is a positive integer. If P is a prime number, our new constructions show that there are Pn sequence of length P and its maximum cross-correlation value is less than or equal to n. These multi-level prime codes can be partitioned into n levels, of which the cross-correlation peak between any two FH codes in level l is at most l ( where l ≤ n ). We analyze the performance of the multi-level prime codes in a conventional ON-OFF key-ing/FH-CDMA (OOK/FH-CDMA) system with hard-limiting detection, and provide the hit probability qn,0, qn,1, …, qn,n of having the cross-correlation values 0, 1, …, n, respectively. Our results show that there is a trade-off between code performance and cardinality.
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