Method and apparatus for estimating modulation accuracy of OFDM_TDD system

A modulation accuracy and adjusted technology, applied in the direction of multi-frequency code system, multi-carrier system, baseband system components, etc., can solve the influence of nonlinear products, the distortion of the amplitude-frequency characteristics of the channel filter, and the EVM of the OFDM_TDD system is not given test methods etc.
CN101499982AActive Publication Date: 2009-08-05DATANG MOBILE COMM EQUIP CO LTD
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Patent Information

Authority / Receiving Office
CN ยท China
Current Assignee / Owner
DATANG MOBILE COMM EQUIP CO LTD
Publication Date
2009-08-05

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Abstract

The invention discloses a method for estimating the precision modulation of an orthogonal frequency division multiplexing (OFDM_TDD) system of time division multiplexing. The method comprises the following steps: received I and Q path signals are filtered and extracted, and the time shift and frequency shift of the extracted signals are adjusted; the the adjusted signals are demodulated to generate measurement signals; hard decision is carried out to the measurement signals, and the measurement signals after hard decision is adjusted to generate reference signals; error signals are obtained by decreasing the reference signals from the measurement signals and an error vector magnitude (EVM) is obtained through calculation according to the error signals and the reference signals. The invention also discloses a device for estimating the modulation precision of the OFDM_TDD system of time division multiplexing. The application of the method is capable of obtaining the EVM without the processing of channel decoding by generating the reference signals and the measurement signals after the signals are adjusted. The method is a proposal for the estimation of the modulation precision applicable to the OFDM_TDD systems.
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Description

technical field

[0001] The invention relates to the technical field of mobile communication, in particular to a method and a device for estimating the modulation precision of an Orthogonal Frequency Division Multiplexing (OFDM_TDD) system of time division multiplexing. Background technique

[0002] Error vector value (EVM), also known as correlation constellation error, is an important indicator for measuring modulation quality in digital communication systems. The third generation mobile communication system, including Wideband Code Division Multiple Access (WCDMA), CDMA2000, Time Division-Synchronous-Code Division Multiple Access (TD-SCDMA), etc. , and the Worldwide Interoperability Microwave Access (WIMAX) protocol stipulate that the modulation accuracy is measured by EVM.

[0003] The EVM indicators that affect the output signal mainly include the following factors:

[0004] 1. The amplitude of the input I and Q signals is unbalanced;

[0005] 2. Quadrature modulator ...

Claims

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