以FPGA實現在正交分頻多工系統上新的載波干擾抑制技術

Implementation of a Novel Inter-Carrier Interference Suppression Scheme for OFDM System in FPGA

鄭令宜(Ling-Yi Cheng)

指導教授 ： 許孟烈

國立暨南國際大學/科技學院/通訊工程研究所/碩士(2009年)

https://doi.org/10.6837/NCNU.2009.00092

摘要

正交分頻多工調變技術(Orthogonal Frequency Division Multiplexing, OFDM)是一種相當可靠且非常適合在高速傳輸的調變技術，然而OFDM對於頻率偏移所造成的載波間干擾（inter carrier interference, ICI）特別敏感，因此系統效能很容易受到載波間干擾而大幅地降低。載波間干擾自我消除技術(ICI Self-Cancellation Scheme)，因其容易實現以及效能穩定而受到重視，然而在頻率偏移較大的時候，往往無法提供令人滿意的效果。在本論文中，我們提出了一個新的抑制ICI方法，利用信號共軛分配的方式提供鏡射，而能在保持信號相位之下達到ICI的自我消除，並不需要額外增加系統演算的複雜度。由模擬結果顯示，新的抑制ICI方法在位元錯誤率上優於ICI自我消除技術的效能。最後，我們將此方法實現在可程式邏輯閘陣列 (Field Programmable Gate Array, FPGA)發展板上，證實此方法之可行性。

關鍵字

正交分頻多工調變技術 ； 載波間干擾 ； 可程式邏輯閘陣列

並列摘要

Orthogonal frequency division multiplexing (OFDM) system is a modulation technique which is reliable and very suitable for high data rata transmission. However, OFDM is highly sensitive to carrier frequency offset (CFO) which results in inter-carrier interference (ICI). Therefore system performance is easily reduced by inter-carrier interference (ICI). ICI self-cancellation scheme has received much attention due to its simplicity and high robustness to frequency offset errors. However, they can not provide satisfactory performance for large carrier frequency offset. In this thesis, we propose a novel scheme of ICI suppression utilizes the conjugate data allocation on adjacent subcarriers to preserve the signal phase without additional algorithmic complexity of the system. Simulation results show that the proposed scheme outperforms ICI self-cancellation scheme for BER performance. Finally, we have implemented and verified the proposed scheme in Field Programmable Gate Array (FPGA).

並列關鍵字

OFDM ； ICI ； FPGA

參考文獻

[1] Y. Zhao and S. G. Häggman, “Intercarrier interference self-cancellation scheme for OFDM mobile communication systems,” IEEE Transactions on Communications, vol. 49, no. 7, pp. 1185-1191, July 2001.

[2] Richard van Nee, Ramjee Prasad, OFDM wireless multimedia communication, Artech House Boston London, 2000.

[3] John A. C. Bingham, ADSL, VDSL, and multicarrier modulation, Wiley-Intersciencem, 2001.

[4] 溫志宏,劉宗憲,邱茂清,林仁勇,連振凱,林進豐,李國瑞,正交分頻多重進接技術, 滄海書局. Jul. 2007.

[5] Y. R. Lin, FPGA Implementation of 100Mbps OFDM Transceiver, M.S. thesis, Dept. Elec. Eng., National Chi Nan Univ., Puli, Taiwan, 2008.