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Adaptive Overlap-Add Equalization For Mb-Ofdm Ultra-Wideband, Darryn Lowe, Xiaojing Huang
Adaptive Overlap-Add Equalization For Mb-Ofdm Ultra-Wideband, Darryn Lowe, Xiaojing Huang
Faculty of Informatics - Papers (Archive)
A zero-pad can be used with orthogonal frequency division multiplexing (OFDM) for low-complexity robustness against multipath interference. In this paper, we use adaptive overlap-add (OLA) equalization for improvements of up to 0.6 dB improvement when used with multi-band OFDM (MB-OFDM) ultra-wideband in multipath channels. A theoretical model that relates the size of OLA window to post-equalizer signal-to-noise ratio is derived. An approximating algorithm is then developed that is suitable for low-complexity implementation, with Monte Carlo simulations used to quantify the performance improvements. We conclude that adaptive OLA equalization is computationally simple and can be implemented while remaining fully compliant with …
Ultra-Wideband Mb-Ofdm Channel Estimation With Complementary Codes, Darryn Lowe, Xiaojing Huang
Ultra-Wideband Mb-Ofdm Channel Estimation With Complementary Codes, Darryn Lowe, Xiaojing Huang
Faculty of Informatics - Papers (Archive)
In this paper, we design complementary codesets that significantly improve the quality of channel estimation in orthogonal frequency division multiplexing (OFDM) communication systems, with a focus on the recent MB-OFDM ultra-wideband (UWB) standard. The proposed time-domain OFDM channel estimation technique incurs only a nominal increase in computational complexity and is able to be readily retrofitted into the existing MB-OFDM standard. The underlying complementary codesets, found via an evolutionary algorithm, combine with the existing preamble synchronization sequences to yield asymptotically ideal auto-correlation functions (ACFs). We show how improvements exceeding 1 dB can be achieved in end-to-end packet error rate relative to …
Adaptive Low-Complexity Mmse Channel Estimation For Ofdm, Darryn Lowe, Xiaojing Huang
Adaptive Low-Complexity Mmse Channel Estimation For Ofdm, Darryn Lowe, Xiaojing Huang
Faculty of Informatics - Papers (Archive)
In this paper we present extremely low-complexity adaptive infinite impulse response (IIR) filters that approximate minimum mean square error (MMSE) channel estimation in orthogonal frequency-division multiplexing (OFDM) systems. We show how the packet error rate (PER) can be significantly improved over conventional zero-forcing (ZF) estimation without incurring a significant increase in computational complexity. All quantitative results are provided in the context of multi-band OFDM (MB-OFDM) ultra-wideband (UWB) with standard IEEE channel models.
Middle School Mathematics Teacher Certification, Degree Level, And Experience, And The Effects On Teacher Attrition And Student Mathematics Achievement In A Large Urban District, Bonnie Swan
Electronic Theses and Dissertations
The purpose of this study was to examine the backgrounds and experiences of middle school mathematics teachers that often distinguish "quality" teachers, including certification, experience, degree type, and degree level and how those demographics and others vary for different types of schools. The emphasis was on profiling teachers in a large urban district by describing their basic features and distributions, as well as how middle school mathematics teachers, according to those differences, relate to student mathematics achievement, teacher attrition and teacher mobility. Student achievement was measured by test results from the Norm Reference Test-Normal Curve Equivalent (NRT-NCE) mathematics portion of …