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Proposal of Power Saving Techniques for Wireless Terminals Using CAZAC-OFDM Scheme

Authors:
Takanobu Onoda
Ryota Ishioka
Masahiro Muraguchi

Keywords: OFDM; CAZAC; polar modulation; SEPP;

Abstract:
A major drawback of Orthogonal Frequency Division Multiplexing (OFDM) signals is extremely high Peak-to-Average Power Ratio (PAPR). Signals with high PAPR lead to a lowering of the energy efficiency of the Power Amplifiers (PAs) and the shortened operation time causes a serious problem in battery-powered wireless terminals. In this paper, we propose a new power saving technique for wireless terminals. It is the combination of a polar modulation technique and CAZAC (Constant Amplitude Zero Auto-Correlation) equalizing technique. Proposed the polar modulation technique for the PA employs a current control by changing the common-gate stage bias in a cascade amplifier circuit. The CAZAC equalization scheme makes the PAPR of M-array Quadrature Amplitude Modulation (M-QAM) OFDM signals into the PAPR of M-QAM single-carrier signals. By using CAZAC-OFDM signal, proposed polar modulation PA exhibits overall efficiency of 40% at Error Vector Magnitude (EVM) of -32dB. Furthermore, a breakthrough technique which transcends barrier of 50% efficiency has been proposed. A prototype of Single Ended Push-Pull amplifier (SEPP AMP) exhibits power gain of 11dB over 100MHz to 1GHz, the maximum efficiency of 65% without polar modulation scheme.

Pages: 115 to 120

Copyright: Copyright (c) IARIA, 2018

Publication date: July 22, 2018

Published in: conference

ISSN: 2308-4030

ISBN: 978-1-61208-650-7

Location: Barcelona, Spain

Dates: from July 22, 2018 to July 26, 2018