Performance Comparison of Taylor Series Approximation and CORDIC Algorithm for an Open-Loop Polar Transmitter

Open-Loop Polar Transmitter에 적용 가능한 테일러 급수 근사식과 CORDIC 기법 성능 비교 및 평가

  • Kim, Sun-Ho (School of Electronic Engineering, Soongsil University) ;
  • Im, Sung-Bin (School of Electronic Engineering, Soongsil University)
  • 김선호 (숭실대학교 정보통신전자공학부) ;
  • 임성빈 (숭실대학교 정보통신전자공학부)
  • Received : 2010.06.17
  • Published : 2010.09.25

Abstract

A digital phase wrapping modulation (DPM) open-loop polar transmitter can be efficiently applied to a wideband orthogonal frequency division multiplexing (OFDM) communication system by converting in-phase and quadrature signals to envelope and phase signals and then employing the signal mapping process. This mapping process is very similar to quantization in a general communication system, and when taking into account the error that appears during mapping process, one can replace the coordinates rotation digital computer (CORDIC) algorithm in the coordinate conversion part with the Taylor series approximation method. In this paper, we investigate the application of the Taylor series approximation to the cartesian to polar coordinate conversion part of a DPM polar transmitter for wideband OFDM systems. The conventional approach relies on the CORDIC algorithm. To achieve efficient application, we perform computer simulation to measure mean square error (MSE) of the both approaches and find the minimum approximation order for the Taylor series approximation compatible to allowable error of the CORDIC algorithm in terms of hardware design. Furthermore, comparing the processing speeds of the both approaches in the implementation with FPGA reveals that the Taylor series approximation with lower order improves the processing speed in the coordinate conversion part.

Acknowledgement

Supported by : 한국연구재단

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