動態頻譜存取環境中以生物粒子演算法做最佳化能量分配

The power allocation by Particle Swarm Optimization in Dynamic Spectrum Access environments

周武億(Wu-I Chou)

指導教授 ： 林宗男

國立臺灣大學/電機資訊學院/電信工程學研究所/碩士(2010年)

https://doi.org/10.6342/NTU.2010.01739

摘要

在現今環境中，無線網路的使用者數目呈現驚人的成長，這也是由於網路多媒體應用程式的高度開發，因此無線網路的使用率越趨熱絡。但是無線網路的頻譜是珍貴且稀少並且是無法製造的，因此如何在有限的頻譜下做到最妥善頻段利用是目前最重要的研究方向。根據美國FCC 調查，目前各國的執照頻譜使用率僅10%不到，這是一個相當低且無法接受的使用率。因此目前科學家已經提出動態頻譜存取來大幅提高頻譜的使用率，而動態頻譜存取的核心問題便是討論如何在不影
響執照使用者(優先使用者)的情況下來決定次要使用者(非執照使用者)的傳輸能量來達到最高的次要使用者的傳輸效率。雖然這個問題在先前已經有人著手解決，但是當網路環境變成多重頻道(多重優先使用者)以及多重次要使用者時，這個問題將變成非常棘手且難解的問題。而大多數之前文獻上提出的方法都是近似解僅能解出次佳解而不是最佳解。因此，本篇論文提出一個新的演算法來有效率的解決動態頻譜能量分並且是在多重頻道以及多重次要用戶的環境下，而本篇論文提出的演算法能快速有效率的得到能量分配的最佳解，使得次要使用者在不影響優先使用者的情況下有最大的總和傳輸效率。

關鍵字

動態頻譜 ； 能量分配 ； 傳輸效率 ； 最佳化 ； 多重使用者 ； 多重頻道

並列摘要

It is well known that wireless spectrum is a very limited and treasur-able resource for communications. However, the wireless spectrum istruly underutilized in both spectral and time domain so far. Fortu-nately, it has been found that using dynamic spectrum access (DSA)in cognitive radio networks can significantly improve the spectral efficiency by allowing secondary users to access primary channels without interfering primary users. The dynamic spectrum access is not only managing the channel allocation but also power control with the objective to maximize the aggregate throughput of all secondary users. However, when it comes to a multi-user and multi-channel cognitive radio networks condition this problem becomes much more difficult. In the literature this kind of problem is often formulated as a mixed integer nonlinear programming (MINLP), but this problem is an NP-hard problem and it is also hard to solve. Hence, there are some approximation methods proposed to solve this problem which can only led to the suboptimal solutions. Therefore, we propose a novel algorithm to solve this problem and find the optimal solution instead of sub-optimal solution. In the literature [1] , this dynamic spectrum access problem has been carefully reexamined and found that this problem has been over-parameterized. We show that this problemcould be formulated as a nonlinear programming (NLP) without losing globally optimal objective function value. And we can solve this problem by using interior point DSA optimization algorithm in polynomial time. In our paper we use particle swarm optimization (PSO)
to find the optimal solution quick and correct, moreover, by using interior point methods can help us to choose the appropriate region to throw particles which can decrease searching time and cost. Finally, simulation results show performance of our proposed algorithm.

並列關鍵字

Dynamic spectrum access ； cognitive radio networks ； particle swarm optimization ； interior point

參考文獻

[1] T. L. Pochiang Lin, “Optimal dynamic spectrum access in multi-channel

[2] T. Shu and M. Krunz, “Coordinated channel access in cognitive radio net-

[3] A. T. Hoang, Y.-C. Liang, and M. Islam, “Power control and channel allo-

cation in cognitive radio networks with primary users’ cooperation,” IEEE

[4] M. A.McHenry, “Nsf spectrum occupancy measurements, project summary,”