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Multipath Diversity Of Precoded Ofdm With Linear Equalization, Xiaojing Huang
Multipath Diversity Of Precoded Ofdm With Linear Equalization, Xiaojing Huang
Faculty of Informatics - Papers (Archive)
This paper settles a controversy over the multipath diversity performance of the precoded orthogonal frequency division multiplexing system with the linear equalization. Through the asymptotical analysis of the bit error rates with extreme system parameters, a comprehensive understanding of the linear equalization's behavior in the frequency-selective multipath fading channels is gained. Compared with the optimum maximum-likelihood detection, the diversity performance of the linear equalization can be well described by an asymptotical signal-to-noise ratio (SNR) degradation, which reveals that the linear equalization can achieve the maximum multipath diversity within an operational SNR range but will lose diversity advantage as SNR increases.
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.