http://hdl.handle.net/1957/7303 This collection includes scholarly articles produced by EECS faculty and students. 2013-05-25T06:20:41Z http://hdl.handle.net/1957/38188 Highly Linear Noise-Shaped Pipelined ADC Utilizing a Relaxed Accuracy Front-End Rajaee, Omid; Moon, Un-Ku A noise-shaped pipelined ADC is presented in this paper. A minimal complexity ΔΣ modulator in the first two sub-ADCs and residue feedback in the latter stages lead to high-order noise shaping. This also leads to reduced sensitivity to analog imperfections in the front-end stage. Implemented in 0.18μ m CMOS, the ADC achieves 12 ENOB with 64 MHz clock at 6X OSR while using only a 9-bit linear front-end multiplying-DAC (MDAC). The delta-sigma sub-ADCs dissipate 400μ W extra power (out of 13.9mW total power) while significantly enhancing the the overall ADC linearity. This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by IEEE-Institute of Electrical and Electronics Engineers and can be found at: http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=4. (c) 2013 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works. 2013-02-01T00:00:00Z http://hdl.handle.net/1957/38104 Computationally Efficient Lattice Reduction Aided Detection for MIMO-OFDM Systems under Correlated Fading Channels Liu, Wei; Choi, Kwonhue; Liu, Huaping We analyze the relationship between channel coherence bandwidth and two complexity-reduced lattice reduction aided detection (LRAD) algorithms for multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems in correlated fading channels. In both the adaptive LR algorithm and the fixed interval LR algorithm, we exploit the inherent feature of unimodular transformation matrix P that remains the same for the adjacent highly correlated subcarriers. Complexity simulations demonstrate that the adaptive LR algorithm could eliminate up to approximately 90 percent of the multiplications and 95 percent of the divisions of the brute-force LR algorithm with large coherence bandwidth. The results also show that the adaptive algorithm with both optimum and globally suboptimum initial interval settings could significantly reduce the LR complexity, compared with the brute-force LR and fixed interval LR algorithms, while maintaining the system performance. This is the publisher’s final pdf. The published article is copyrighted by Electronics and Telecommunications Research Institute and can be found at: http://etrij.etri.re.kr/. 2012-08-01T00:00:00Z http://hdl.handle.net/1957/38103 Efficient Congestion Control Utilizing Message Eavesdropping in Asynchronous Range-Based Localization Choi, Hoon; Baek, Yunju; Lee, Ben Asynchronous ranging is one practical method to implement a locating system that provides accurate results. However, a locating system utilizing asynchronous ranging generates a large number of messages that cause transmission delays or failures and degrades the system performance. This paper proposes a novel approach for efficient congestion control in an asynchronous range-based locating system. The proposed method significantly reduces the number of messages generated during the reader discovery phase by eavesdropping on other transmissions and improves the efficiency of ranging by organizing the tags in a hierarchical fashion in the measurement phase. Our evaluation shows that the proposed method reduces the number of messages by 70% compared to the conventional method and significantly improves the success rate of ranging. This is the publisher’s final pdf. The published article is copyrighted by the Electronics and Telecommunications Research Institute and can be found at: http://etrij.etri.re.kr/. 2013-02-01T00:00:00Z http://hdl.handle.net/1957/37567 Skill progression demonstrated by users in the Scratch animation environment Scaffidi, Christopher; Chambers, Christopher The Scratch environment exemplifies a tool+community approach to teaching elementary programming skills, as it includes a website where users can publish, discuss, and organize animations that are programs. To explore this environment’s effectiveness for helping people to develop programming skills, we performed a quantitative analysis of 250 randomly-selected users’ data, including over 1000 of their animations. We measured skill based on four models that had proven useful in prior empirical studies. Overall, we found mixed results about the environment’s effectiveness. Among users who do not drop out, we found an increasing progression in social skills. However, we also observed an extremely high drop-out rate. Moreover, we observed a flat or decreasing level of demonstrated skill on virtually every measure. These results call into question whether simply combining an animation tool and an online community is sufficient for keeping people engaged long enough to learn elementary programming skills. This is the author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Taylor & Francis and can be found at: http://www.tandfonline.com/toc/hihc20/current. 2012-01-01T00:00:00Z