適用於無線都會區域網路中正交分頻多工存取模式之上行基頻接收機設計與實作

為了提供更完善的無線通訊服務，無線都會區域網路標準IEEE 802.16e-2005應運而生。因無線網路的便利性，用戶端只需要安裝符合IEEE 802.16e-2005標準的收發機，在各種不同的環境下，包含市區、郊區、固定或移動端用戶，都可享受無線寬頻上網的功能。此外藉由無線網路接收機的安裝，還可省去業者佈線的高昂成本。本論文設計一符合IEEE 802.16e-2005正交分頻多工存取模式之基地端實體接收機，並以C++程式撰寫實現，可操作在靜態或是動態環境通道。接收機針對量測碼偵測、量測碼邊界估測、載波頻率飄移偵測與補償、通道估測、載波間干擾消除等演算法進行開發與研究。其中在量測碼偵測與邊界估測分別使用頻域差動解碼與時域相關器組，模擬結果顯示在低SNR時即可成功偵測到量測碼並估測其邊界。在通道估測部分提出一套針對在動態環境下正交分頻多工存取模式的決策輔助通道估測演算法。另外在載波間干擾消除等化器部分提出動態環境下正交分頻多工存取模式的類球面搜尋等化器，模擬比較結果證明本論文提出之演算法比現今常見演算法有較好的估測與等化效能。最後，在各式通道模型下，本論文所提出的架構可以有效的對抗多重路徑瑞雷衰減、載波頻率與取樣時脈飄移的影響，並在動態環境都普勒效應的通道下減少錯誤發生的機率，增進系統效能，成功的將資料解調還原。

關鍵字

正交分頻多工存取；通道估測；載波間干擾消除

並列摘要

In this thesis, design and implementation of an IEEE 802.16e-2005 OFDMA uplink receiver is presented. To synchronize with un-registered mobile subscribers, frequency domain differential decoder is applied to detect ranging codes which are transmitted from mobile subscribers. Time domain correlator bank is used to precisely estimate ranging symbol boundary. Also wighted least square algorithm and parallel interference cancellation (PIC) are adopted to estimate and conpensate carrier frequency offset (CFO). Since high mobility is supported in IEEE 802.16e-2005 and OFDMA systems are well-known to be vulnerable to Doppler frequency spread which is caused by time-selective channel, a novel decision-aided channel estimation algorithm and sphere-search-like ICI-mitigation equalizer are proposed to reduced error floor and enhance system performance. Numerical simulation results and comparisons show that proposed algorithms have more accurate channel estimation result and better system performance. The overall system simulation results under different channel models show that proposed receiver can combat multi-path Rayleigh fading channel which incorporates with receiver non-ideal effects, including CFO and SCO, and recover data successfully. Also error floor caused by doubly-selective channel will be reduced due to use proposed novel channel estimation and ICI mitigation algorithm.

並列關鍵字

OFDMA ； channel estimation ； ICI mitigation ； ICI cancellation

參考文獻

[1] IEEE Std 802.16-2004, Standard for Local and Metropolitan Area Networks Part 16: Air Interface For Fixed and Mobile Broadband Wireless Access Systems.

[6] Kang-Chuan Chang, Design and Implementation of a Baseband Receiver for IEEE 802.16e-2005 OFDMA Mode Mobile Station, M.S. thesis, National Taiwan University, Taipei, July 2007.

[10] .Dent, G.E. Bottomley, and T. Croft, “Jakes Fading Model Revisited,” IEEE Electron. Letter, vol. 29, no. 13, pp. 1162-1163, Jun. 1993.

[14] Tiejun Wang, Proakis, J.G., Zeidler, J.R., “Techniques for suppression of intercarrier interference in OFDM systems”, in Proc. of IEEE Wireless Communications and Networking Conference, vol.1, pp. 39-44, March, 2005

[15] Grandmaison, M.-E., Gagnon, F., “Channel Estimation Algorithms for Uplink OFDMA Tiles”, in Proc. of International Symposium on Wireless Pervasive Computing, Feb. 2007

國際替代計量

適用於無線都會區域網路中正交分頻多工存取模式之上行基頻接收機設計與實作

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