Generation of OFDM signal with envelop pulse-width modulation (EPWM) transmitter employing 2nd-order delta-sigma modulator

College

Gokongwei College of Engineering

Department/Unit

Electronics And Communications Engg

Document Type

Conference Proceeding

Source Title

IEEE 5th Asia Pacific Wireless Conference

Publication Date

2008

Abstract

OFDM achieves high spectral efficiency in wireless communication systems. However, it is difficult ti achieve high power efficiency because of its large PAPR. Envelope Pulse-Width Modulation (EPWM) transmitters have been proposed to obtain high power efficiency for the amplification of OFDM signals. This paper proposes an EPWM transmitter which employs the 2nd order Δ-∑ modulator with a null-response frequency. Expression for quantization noise power is theoretically derived to estimate in-band and adjacent channel quantization noise power. The power spectral density (PSD) of the IEEE 802.11a OFDM signal generated with the transmitter is calculated changing the null-response frequency. The adjacent channel leakage power ratio (ACLR) of the OFDM output signal is calculated from the PSD. It is shown that the null-response frequency of 20 MHz give the minimum ACLR for the transmitter.

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Disciplines

Electrical and Computer Engineering

Keywords

Pulse modulation (Electronics); Orthogonal frequency division multiplexing; Electronic noise

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