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Exploring the Hot-Carrier Effect on the Wireless Transceivers

by Herlekar, Sameer R.

Abstract (Summary)
Phase noise can be regarded as the most severe cause of performance degradation in the wireless communication systems. The hot-carriers (HCs), found in the CMOS synchronization circuits, are the high-energy charge carriers that degrade the MOSFET devices performance by increasing the threshold voltage required to operate the MOSFETs. The HC effect manifests itself as the phase noise whose level increases with the continued MOSFET operation and such increases result in the performance degradation of the voltage-controlled oscillator (VCO) built on the MOSFETs. The HC effect is particularly evident in the short-channel MOSFET devices. In this dissertation, we analyze the wireless transceiver performances in the presence of the synchronization errors induced by the HC effect, for both single-carrier and multi-carrier communication systems. We derive the relationship between the corresponding system performances and the HC effect in terms of a crucial parameter, the MOSFET threshold voltage. We employ a new phase noise model for the wireless systems influenced by the HC effect, which is based on a new precise phase noise mask function. In addition, we analyze the impact of the phase noise arising from the HC effect on the single-carrier wireless systems in terms of the BER and the signal-to-interference-plus-noise ratio (SINR). We derive the exact BER expression and show the SINR degradation for the QPSK systems that suffer from the phase noise. We apply Monte Carlo simulations to verify our analysis. To study the HC effect thoroughly, we simplify the BER expression as a new asymptotical analysis as the signal-to-noise ratio approaches to infinity and obtain the lower bound of the achievable BER for the single-carrier wireless systems. For multi-carrier systems, we focus our discussions on the orthogonal frequency division multiplexing (OFDM) systems. According to our simulations, we show that the bit-error-rate (BER) evaluation for OFDM using our new phase noise model in the presence of the HCs can be very different up to three orders-of-magnitude from the existing models disregarding the HCs. We have also found that the ICI self-cancellation coding is very effective for combating the phase noise in the OFDM systems.
Bibliographical Information:

Advisor:Peter Wolenski; Jianhua Chen; Jurgen Hurrelbrink; Subhash Kak; Ashok Srivastava; Hsiao-Chun Wu

School:Louisiana State University in Shreveport

School Location:USA - Louisiana

Source Type:Master's Thesis

Keywords:electrical computer engineering

ISBN:

Date of Publication:06/14/2006

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