一般而言，在感知無線電網路中，我們希望極大化次要使用者的傳輸量。在本論文中，一個感知無線電網路系統，在通道容量的限制下，我們去探討次要使用者的最大傳輸量問題。藉由KKT 定理，可得到一個目標函數，利用此目標函數，來獲得次要使用者的最佳個數。並且舉例數值結果實驗來做說明。在本實驗中，最重要的結果是，為了達到最大次要使用者的傳輸量，並不是合作所有次要使用者，而是合作某一數目的次要使用者。

In a CR network, the maximum SUs throughput is desired generally. In this thesis, We
investigate and formulate the problem of the secondary users’ throughput maximization in
cognitive radio systems under channel capacity constrain. By using KKT theorem, an objec-
tive function is developed to obtain an optimal solution for the SU throughput maximization
problem. An numerical example is also presented for illustration. The most important results
revealed in the example show that the maximum SU throughput is achieved by cooperating an
optimal number of SU pairs instead of cooperating all the SU pairs.

1 Introduction 1
1.1 Motivation and objective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Thesis Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2 System Model 5
2.1 System model for spectrum sensing . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2 Local detection for spectrum sensing . . . . . . . . . . . . . . . . . . . . . . . . 6
2.3 Cooperative Spectrum Sensing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3 The Secondary Users’ Throughput Maximization 9
3.1 Problem formulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.2 Optimal solution scheme development . . . . . . . . . . . . . . . . . . . . . . . . 10
4 Numerical Examples 13
4.1 The effect of interference channel fading coefficient : |g|2 . . . . . . . . . . . . . 14
4.2 The effect of primary user’s transmission rate : Rp . . . . . . . . . . . . . . . . . 17
4.3 The effect of the primary user’s transmission power : Pp . . . . . . . . . . . . . 20
4.4 The effect of the probability for which the PU is inactive : P(H0) . . . . . . . . 23
5 Conclusions 26
6 Appendix 27

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