正交分頻多工帶外功率譜散逸降低法

the reduction of out-of-band power emission in OFDM

季昀聖(Yun-Sheng Ji)

指導教授 ： 許超雲

大同大學/電機資訊學院/通訊工程研究所/碩士(2005年)

摘要

隨著數位通訊產業的越發成熟，我們於這有限寬度的頻帶上，有著越來越高的使用率，因此，頻道的分配使用問題變的更加重要，且各系統間頻道相互干擾與衝突的問題越發嚴重。因此頻帶間干擾的抑制成為一個重要的議題。
為了能夠有高的頻寬使用率，我們提出一種可明顯降低帶外頻譜功率的方法，來降低自身頻道對其他頻道的干擾。並且進一步修正本方法原有的缺點：在本身主頻帶內高頻處有過高功率值。
根據本方法的概念所做的模擬結果，有著以下的優點：
1. 僅需將修正資訊安插入兩個空的子載波中，而不需要對其他子載波進行更動。
2. 有效降低帶外功率譜散逸問題。
3. 本身主頻帶內高頻處過高功率值問題可被明顯抑制。
4. 提高頻帶使用效率。
5. 不需要更動原有的硬體架構。

關鍵字

正交分頻多工 ； 帶外功率譜

並列摘要

Due to the growth in wireless communications, more efficient utilization of spectrum is necessary. The increased sharing of spectrum translates into a higher likelihood of users interfering with one another. Therefore, interference rejection becomes an important issue in digital wireless communications.
In order to gain high bandwidth efficiency, we try to reduce the out-of-band power. By our proposed method, it can reduce the adjacent interference indeed. By the way, this method has drawback: peak-power phenomenon. To eliminate this problem, we add a constraint, and solve it indeed. Thus, the object of gaining high bandwidth efficiency will be achieved and more channels may be allowed in the specific frequency band.
According to our simulation, two advantages can be achieved as follows:
1. We only need to insert two auxiliary data into the original null subcarriers for reducing out-of-band power.
2. Reduce the out-of-band power spectrum.
3. The drawback of peak-power phenomenon can be reduced dramatically.
4. Increase the spectral efficiency.
5. Do not need to change hardware of current systems.

並列關鍵字

OFDM ； out-of-band

參考文獻

[1] R. van Nee and R. Prasad, “OFDM for wireless multimedia communications,” 2000.

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Broadcasting, Vol. 41, NO.1, March 1995

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[7] B.Sklar and E. Okamoto, “ Rayleigh fading channels in mobile digital communication