適用於正交多工分頻存取系統之感知無線電頻譜偵測

為了徹底使用無線電資源進而增加頻譜使用效率，感知無線電會偵測環境以及辨識訊號來源，如此次要通訊系統得以和主要通訊系統共存，因此偵測和感知在感知無線電中扮演著重要的角色。在本篇論文中，我們針對正交多工分頻存取系統由於它在未來通訊系統的潛力以及在頻譜偵測的困難度，對於此系統，在提出的頻譜偵測週期之下我們獲得一組有效的感知資訊。為了避免干擾主要通訊系統，第一步是偵測主要通訊系統是否存在以及是否有使用者在使用此系統，在此我們透過量測接收訊號強度、追蹤符碼率的基本頻率、偵測正交多工分頻存取訊號的循環性以及無線通訊系統的控制信號，模擬結果顯示即使訊號雜訊比很低仍然能夠逼近完美的偵測。接著由於事前知道訊框的架構，藉由解訊框表頭我們能夠獲得資料傳輸速率和無線電資源分配狀況，最後透過無線通訊系統中速率和距離關係式決定出感知無線電所擁有的無線電資源並且同時保證對於主要通訊系統的干擾程度，此外藉由參數調整，我們的偵測程序能夠適用於當今任何先進的正交多工分頻存取系統。

關鍵字

感知無線電；無線電資源；頻譜使用率；頻譜偵測；偵測/感知週期；正交多工分頻存取系統；速率距離關係

並列摘要

In order to fully exploit wireless radio resource and then increase spectrum efficiency, cognitive radios for future wireless communication systems shall sense wireless environments and identify interference so that the secondary system(s) may coexist with primary communication systems. As a result, sensing and cognition play a major functionality in cognitive radios. In this thesis, we acquire an effective set of cognitive information under a proposed spectrum sensing cycle for orthogonal frequency division multiple access (OFDMA) systems because of their potential and challenges. To avoid interfering with primary systems, detecting existence and activity of the primary system by measuring RSSI, tracking fundamental symbol rate of the primary system and is the first step in coexistence. Furthermore, using cyclic property of OFDMA signal and control and management signal in wireless communication systems, we can precisely determine existence and activity of the target OFDMA system in one frequency band, via Neyman-Pearson criterion. Simulation results show that near perfection detection is achieved even at low SNR. With a priori knowledge of frame structure in potential primary systems, communication parameters, such as data transmission rate and resource allocation state, can be extracted by decoding frame header. Finally, we can determine available radio resource with respect to cognitive radios using rate-distance relationship, while guarantee interference to primary systems. Moreover, by parametric adjustment, our sensing procedure can be applied to any state-of-the-art OFDMA systems nowadays.

並列關鍵字

Cognitive radio ； radio resource ； spectrum efficiency ； spectrum sensing ； sensing/cognition cycle ； orthogonal frequency division multiple access (OFDMA) ； rate-distance relationship

參考文獻

[1] J. Mitola III, "Software radio architecture: a mathematical perspective," Selective Areas in Communications, IEEE Journal on, vol. 17, pp. 514-538, Apr. 1999.

[2] ------, “Cognitive radio for flexible mobile multimedia communications,” Mobile Multimedia Communications, IEEE International Workshop on, pp. 3-10, Nov. 1999.

[6] N. Devroye, P. Mitran, and V. Tarokh, “Achievable rates in cognitive radio channels”, IEEE Tran. Information Theory, vol. 52, pp. 1813-1827, May 2006.

[9] 3GPP home page: http://www.3GPP.org

[11] S. Parkvall, E. Englund, M. Lundevall, and J. Torsner, “Evolving 3G mobile systems: broadband and broadcast services in WCDMA,” IEEE Communication Magazine, pp. 68-74, Feb. 2006.

國際替代計量

適用於正交多工分頻存取系統之感知無線電頻譜偵測

全文下載

主題瀏覽