內建編碼輔助式訊雜比估測器之定位技術設計與實作

Design and Implementation of Positioning Technique with Embedded Code-Aided SNR Estimator

林明弘(Ming-Hung Lin)

指導教授 ： 黃元豪

國立清華大學/電機資訊學院/電機工程學系/碩士(2012年)

摘要

在無線通訊系統中，訊雜比資訊可以用來觀察環境中的雜訊強度，所以訊雜比估測是一項不可或缺的估測技術。因此，在許多的通訊系統應用中，它們都需要訊雜比資訊來達到系統效能的最佳化。另外，近年來，在美國聯邦通訊委員會提出增強型911的需求之後，行動定位漸漸的成為了熱門的議題。因此，定位技術可藉由結合訊雜比估測技術來增進定位的精準度。由於我們採用的是接收訊號強度式之定位技術，它的定位準確性與接收到的 RSS 有很大的關係。因此，我們藉由編碼輔助式訊雜比估測所估測到之訊雜比資訊對 RSS 作雜訊消除，進而得到更準確的 RSS，而接收訊號強度式之定位技術再藉由雜訊消除後的接收訊號強度提高定位的精準性。經由模擬顯示，編碼輔助式訊雜比估測相較於其他的無資料輔助式訊雜比估測，在低訊雜比的環境下，編碼輔助式訊雜比估測有比較好的較能表現。本論文針對編碼輔助式訊雜比估測器實現其架構的設計，並將編碼輔助式訊雜比估測器整合接收訊號強度式之定位技術後在 FPGA 上做驗證。最後，我們的內建編碼輔助式訊雜比估測器之定位技術藉由射頻模組的幫助來完成現實世界的定位，並且藉由比較接收訊號強度式之定位技術使用有做雜訊消除的 RSS 和沒有做雜訊消除的 RSS，而經由結果顯示前者比後者有比較好的定位效能表現。

關鍵字

編碼輔助式 ； 訊雜比估測器 ； 定位技術

並列摘要

The information of signal-to-noise (SNR) is used to observe the power of noise, so the SNR estimation is an essential technique in wireless communication systems. Hence, many communication system applications require the SNR information to optimize the system performance. Also, the mobile positioning has become a popular issue since the E-911 purpose proposed by FCC. Hence, the positioning technique can cooperate with the SNR estimation to improve precision of positioning. Due to the adoption of the received signal strength (RSS)-based positioning technique in our work, the positioning performance is dominated by the RSS. Hence, the positioning performance can be improved
by RSS with noise cancellation which is estimated by the code-aided (CA) SNR estimation. The simulation results indicate that the CA SNR estimation method has better estimation performance than the other non-data-aided (NDA) SNR estimation methods in low SNR conditions. This thesis propose the architecture design of the CA SNR estimation, and verify the architecture design combined with the RSS-based positioning technique on FPGA. Finally, We use the RSS-based positioning technique with embedded CA SNR estimator to complete positioning estimation by using RF modules in real world, and the simulation results indicate that the RSS with noise cancellation has better performance than the RSS without noise cancellation in the integrated positioning system.

並列關鍵字

Code-Aided ； SNR Estimator ； Positioning Technique

參考文獻

Tsing Hua University, Hsinchu, Taiwan, 2011.

[2] M. A. Dangl and J. Lindner, “How to use a priori information of data symbols for SNR estimation,” IEEE Signal Processing Letters, vol. 13, no. 11, pp. 661–664, Nov. 2006.

[3] N. Wu, H. Wang, and J.-M. Kuang, “Code-aided SNR estimation based on expectation maximisation algorithm,” Electronics Letters, vol. 44, no. 15, pp. 924–925, Jul. 2008.

[4] ——, “Maximum likelihood signal-to-noise ratio estimation for coded linearly modulated signals,” IET Communications, vol. 4, no. 3, pp. 265–271, Feb. 2010.

[5] T. H. Kerr, “A critical perspective on some aspects of GPS development and use,” in Proc. AIAA/IEEE DASC, vol. 2, Oct. 1997, pp. 9.4–9–9.4–20 vol.2.