最近，幾種以Kodialam等人提出的RFID數量估計算法為基礎的新算法相繼出現。這些新算法不僅考慮到RFID讀器和RFID標簽之聞無線信道的不穩定性和不確定性，而且還可以保證其估算具有一定的準確性。然而，這些RFID數量估計算法的設計和性能評估都是基於一個比較簡化的信道模型。根據這個信道模型，封包在RFID讀器和標簽之聞傳送時遺失的概率是符合獨立分布的。然而，一些實證測量研究指出，在一般的室内環境，人的活動和設備的移動對信道的影響是不可忽視的。這些活動可以引起多普勒效應，從而使信號變成時域相關。因此，在真實的無線信道傳輸中，封包的遺失也是時域相關的。由於不同的RFID數量估計算法具體的設計和實現方法各有不同，封包遺失的時域相關性可能對這些RFID數量估計算法造成不同程度的影響。 / 在本論文中，我們評估了三系列的算法在更真實的時域相關的無線信道下的性能。具體來，我們重點研究和分析了時域相關性在哪些方面影響了現有的RFID數量估計算法的準確性。依據描述真實無線信道特性的實驗數據，我們改進了原來的信道模型，使其概括了RFID讀器和標簽之聞向前信道/向後信道的時域相關性。通過觀察這三系列算法在更真實的時域相關的無線信道下的表現，我們分析了造成估算值和真實值之間差距的原因。同時，提出了一些改善數量估計算法準確性的方法，並且通過模擬試驗證明這些改進可以提高算法在真實無線信道下的準確性。 / Recently, several new RFID counting algorithms have been proposed based on the probabilistic counting schemes introduced by Kodialam et. al.. These existing algorithms took into account the unreliable and non-deterministic nature of the radio communication channels between the RFID reader and the tags,and are capable of providing tag-count estimates that satisfy a desired level of accuracy. However, all algorithms were designed and evaluated based on a simplistic packet loss model. It assumes that the loss probability of a packet between the reader and the tag-set follows an independent, identical distribution. No characterizations of possible temporal correlations of the channels were performed. As presented by some empirical measurements, movements of personnel or equipments in a building can generate Doppler effect, which introduces time correlations to the fading signal. Thus, the realistic packet loss caused by the wireless channels is temporally correlated due to the frequent change of the nearby environment. Depending on specific implementation details of each individual algorithm,temporally correlated packet loss might have significant impact on the tag-set cardinality estimation. / In this thesis, we will evaluate the performance of the aforementioned RFID counting algorithms under a more sophisticated time-correlated channel fading model. In particular, we focus on investigating and analyzing how the temporal correlations would influence the accuracy of these existing counting algorithms. Based on the experimental statistics that characterized the realistic indoor channels, we refine the channel model to describe the time-correlation of the forward and backward channel between the RFID reader and the tags. We also modify the model to support implementations of different communication scenarios. Comparisons of the performance of the existing counting schemes under the simplistic uncorrelated packet loss channel model and the refined correlated channel model are conducted. We also propose extensions for these RFID counting schemes to mitigate the estimation inaccuracy generated by the correlated packet loss. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Deng, Yulin. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 99-107). / Abstracts also in Chinese. / Abstract --- p.i / Acknowledgement --- p.vi / Chapter 1 --- Introduction --- p.1 / Chapter 2 --- Background and related work --- p.7 / Chapter 3 --- Modeling time-correlated channels in RFID systems --- p.13 / Chapter 3.1 --- Memoryless channel model --- p.14 / Chapter 3.2 --- Backscattering channel model --- p.16 / Chapter 3.2.1 --- Discussions of channel differences with active tags --- p.18 / Chapter 3.3 --- Difficulties in extending mathematical analysis for Memoryless channel model to time-correlated Backscattering channel model --- p.19 / Chapter 3.4 --- Implementations of Backscattering channel model --- p.20 / Chapter 3.4.1 --- Model the one-way fading channel based on the Clarke and Gans model --- p.20 / Chapter 3.4.2 --- Other implementation aspects of the Twoway Backscattering channel model --- p.25 / Chapter 4 --- Performance evaluation of the First-two-moment implicit approach under time-correlated channels --- p.27 / Chapter 4.1 --- System model --- p.28 / Chapter 4.2 --- Estimator Accuracy --- p.30 / Chapter 4.3 --- Performance evaluation of the First-two-moment implicit RFID counting scheme over time-correlated channels --- p.32 / Chapter 4.3.1 --- Modeling differences --- p.34 / Chapter 4.3.2 --- Coherence time --- p.37 / Chapter 4.3.3 --- Rician fading channel --- p.40 / Chapter 4.3.4 --- Discussions for the case with active tags --- p.42 / Chapter 4.4 --- Correcting estimation errors under time-correlated channels --- p.44 / Chapter 4.4.1 --- Correcting estimation mean --- p.44 / Chapter 4.4.2 --- The impact of time-correlated channels on estimation variance --- p.47 / Chapter 4.5 --- Chapter summary --- p.49 / Chapter 5 --- Performance Evaluation of the Capture-Recapture approach under time-correlated channels --- p.50 / Chapter 5.1 --- System model --- p.51 / Chapter 5.2 --- Different estimation algorithms --- p.53 / Chapter 5.2.1 --- Union-based approach --- p.53 / Chapter 5.2.2 --- The Capture-Recapture approach --- p.55 / Chapter 5.3 --- Performance evaluation of the estimation schemes under time- correlated channels --- p.58 / Chapter 5.3.1 --- Simulation Setup --- p.60 / Chapter 5.3.2 --- Observations and Analysis --- p.65 / Chapter 5.4 --- Extensions of correcting the errors under timecorrelated channels --- p.69 / Chapter 5.5 --- Chapter Summary --- p.72 / Chapter 6 --- Performance evaluation of adaptive RFID counting algorithms under time-correlated channels --- p.74 / Chapter 6.1 --- System Model --- p.75 / Chapter 6.2 --- Adaptive RFID counting Algorithms --- p.76 / Chapter 6.2.1 --- Adaptive Union approach --- p.77 / Chapter 6.2.2 --- Probabilistic Estimation For Lossy Channels (PELOC) --- p.78 / Chapter 6.3 --- Performance evaluation of the adaptive counting algorithms under time-correlated channels --- p.80 / Chapter 6.3.1 --- Simulation Setup --- p.81 / Chapter 6.3.2 --- Observation and analysis --- p.82 / Chapter 6.4 --- Extensions to correct the inaccuracy under timecorrelated channels / Chapter 6.5 --- Chapter Summary --- p.93 / Chapter 7 --- Conclusion and Future work --- p.95 / Bibliography --- p.99

Thesis (M. Phil.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 159-164).

Thesis (Ph.D.)--RAND Graduate School, 2007. / Includes bibliographical references.

Localization and motion control (navigation) are two major tasks for a successful mobile robot navigation. The motion controller determines the appropriate action for the robot’s actuator based on its current state in an operating environment. A robot recognizes its environment through some sensors and executes physical actions through actuation mechanisms. However, sensory information is noisy and hence actions generated based on this information may be non-deterministic. Therefore, a mobile robot provides actions to its actuators with a certain degree of uncertainty. Moreover, when no prior knowledge of the environment is available, the problem becomes even more difficult, as the robot has to build a map of its surroundings as it moves to determine the position. Skilled navigation of a differential drive mobile robot (DDMR) requires solving these tasks in conjunction, since they are inter-dependent. Having resolved these tasks, mobile robots can be employed in many contexts in indoor and outdoor environments such as delivering payloads in a dynamic environment, building safety, security, building measurement, research, and driving on highways. This dissertation exploits the use of the emerging Radio Frequency IDentification (RFID) technology for the design and implementation of cost-effective and modular control techniques for navigating a mobile robot in an indoor environment. A successful realization of this process has been addressed with three separate navigation modules. The first module is devoted to the development of an indoor navigation system with a customized RFID reader. This navigation system is mainly pioneered by mounting a multiple antenna RFID reader on the robot and placing the RFID tags in three dimensional workspace, where the tags’ orthogonal position on the ground define the desired positions that the robot is supposed to reach. The robot generates control actions based on the information provided by the RFID reader for it to navigate those pre-defined points. On the contrary, the second and third navigation modules employ custom-made RFID tags (instead of the RFID reader) which are attached at different locations in the navigation environment (on the ceiling of an indoor office, or on posts, for instance). The robot’s controller generates appropriate control actions for it’s actuators based on the information provided by the RFID tags in order to reach target positions or to track pre-defined trajectory in the environment. All three navigation modules were shown to have the ability to guide a mobile robot in a highly reverberant environment with variant degrees of accuracy.

In this thesis, we propose the method to design tag antennas, which are suitable for radio frequency identification system. The fact that the tag antennas design comes with single layer printed circuit board can achieve cost down of the antennas. For the tag antennas, the aim is to design the RFID tag antenna operating in 860¡V960 MHz which are suitable for both the near- and far-field operations worldwide. The method we use to design tag antenna is the dual loop form with Bow-tie antenna, and we focus on the impedance conjugate matching between the RFID strap and antenna to increase impedance bandwidth and improve reading performance. We can adjust parameter to be suitable for different RFID strap in the design framework. The dual loop structure carries out power coupling efficiently in the near field and can allow the RFID strap to work even in the weak EM wave. According to the result of power coupling simulation, we analyze and discuss which factor will affect the reliability of the identification. Such reliability will help to build RFID system.

Since the inception of the backscatter-radio technology, this field has continually evolved. As a result, this technology is used for a multitude of applications like personnel identification, logistics and assets management and military purposes etc. Radio Frequency Identification (RFID) technology works in several ISM-frequency bands. This work pertains to the design and development of an RF tag that uses 5.8 GHz ISM band for backscatter. This frequency band has many inherent advantages like higher gain antennas, smaller sized tags, increased immunity to conductive object losses, and larger RF bandwidth. The objective of this research is design and prototype development of an RF tag capable of sensing acceleration, angular motion, and shock experienced by an object on which it is installed. The sensed information is modulated onto an incident continuous wave (CW) and backscattered to the reader. Literature research suggested that such work has not been done previously using an RFID platform. The challenges include integration of the sensor, antenna and other electronics to efficiently backscatter the information to the receiver, designing a suitable planar antenna, realtime backscattering of the sensed information, and low power consumption. As a further step, it is required to design and integrate two antennas on RF tag to simultaneously backscatter the same information; and to measure and compare its effect with single antenna tag. The sensed impact/shock and rotational movement information from the inertial sensors (accelerometer and gyroscope) was backscattered instantly and displayed on the custom developed graphical user interface. The development of GUI was not part of this project and was developed by another lab member. RF Tags with single and dual antenna configurations were designed and tested. It was observed that by increasing the number of antennas higher read range can be achieved. Moreover, by doubling the antennas the radar cross-section for the tag was approximately doubled.

Thesis (M.B.A.)--Naval Postgraduate School, December 2003. / "MBA professional report"--Cover. Thesis advisor(s): Ira Lewis, Keebom Kang, Nicholas Dew. Includes bibliographical references (p. 73-75). Also available online.

Thesis (M. Phil.)--University of Hong Kong, 2010. / Includes bibliographical references (leaves 116-120). Also available in print.

published_or_final_version / Industrial and Manufacturing Systems Engineering / Doctoral / Doctor of Philosophy