利用雙曲線的幾何特性對於適性無線電波干涉定位系統的定位精準度進行模型化與最佳化

Abstract

「定位精準度」是評量一個定位系統效能最重要的指標，在現存的各種定位系統中，「無線電波干涉定位法（Radio Interferometric Positioning, RIP）」是少數可以達到公分尺度精準度的定位系統。在這篇畢業論文中，我們動態選擇環境中已知位置的感應點當作無線電波的發射點，藉此改善對於多個目標同時定位時的定位精準度。我們建立了一個誤差估計模型，這個模型可以預測使用任何發射點組合時的定位誤差。利用這個誤差估計模型，我們發展出「適性的無線電波干涉定位法（Adaptive RIP）」，可以根據定位目標的位置選擇最佳的發射點組合。我們實做Adaptive RIP，並且在實際環境中實驗。根據我們的實驗結果，不管在單一目標或是多個目標，Adaptive RIP的定位精準度都比原本的RIP好，平均定位精準度進步了47%~60%。

One of the most important performance objectives for a localization system is positional accuracy. It is fundamental and essential to general location-aware services. The radio interferometric positioning (RIP) method [1] is an exciting ap-proach which promises sub-meter positional accuracy. In this work, we would like to enhance the RIP method by dynamically selecting the best anchor nodes as beacon senders, and further optimizing the positional accuracy when tracking multiple targets. We have developed an estimation error model to predict posi-tional error of the RIP algorithm given different combinations of beacon senders. Building upon this estimation error model, we further devise an adaptive RIP method that selects the optimal sender-pair combination (SPC) according to the locations of targets relative to anchor nodes. We have implemented the adaptive RIP method and conducted experiments in a real sensor network testbed. Experi-mental results have shown that our adaptive RIP method outperforms the static RIP method in both single-target and multi-target tracking, and improves the av-erage positional accuracy by 47%~60% and re-duces the 90% percentile error by 55%~61%.