Patent ID: 6862321
Filing Date: 2005-03-01
Classification: H04L

Abstract:
1. In an orthogonal frequency division multiplexing modulation system, a method of generating a transmission signal, comprising the steps of: determining non-compensation signal points in a two-dimensional plane without considering a signal error caused by digital quadrature modulation, the determined non-compensation signal points corresponding to orthogonal frequency division multiplexing subcarriers having positive and negative angular frequencies, the two-dimensional plane being defined by a real axis and an imaginary axis, the real axis corresponding to real-part signal components, the imaginary axis corresponding to imaginary-parts signal components; determining compensation signal points in the two-dimensional plane on the basis of the determined non-compensation signal points and in response to a signal error caused by digital quadrature modulation if the non-compensation signal points are used, the compensation signal points corresponding to the orthogonal frequency division multiplexing subcarriers having the positive and negative angular frequencies, wherein the compensation signal points corresponding to the orthogonal frequency division multiplexing subcarriers having the positive angular frequencies and the compensation signal points corresponding to the orthogonal frequency division multiplexing subcarriers having the negative angular frequencies are in a predetermined relation; sequentially assigning digital information signal pieces to one of the compensation signal points in response to contents of the digital information signal pieces; and subjecting the digital information pieces to a modulation process including digital quadrature modulation in response to the assignment given by the assigning step to generate a radio-frequency transmission signal including an orthogonal frequency division multiplexed signal containing the orthogonal frequency division multiplexing subcarriers.