Demodulation method of 16QAM in time division synchronized CDMA system

A technology of code division multiple access and time division synchronization, applied in the direction of multi-carrier systems, etc., can solve the problems of increasing processor overhead, reducing processing speed, and large amount of calculation, so as to achieve less calculation, ensure demodulation performance, and improve demodulation efficiency effect

Inactive Publication Date: 2009-07-08
ZTE CORP
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Problems solved by technology

[0007] The 16QAM demodulation method in the existing TD-SCDMA system involves many calculation parameters, and the calculation amount is relatively large, which increases the overhead of the processor and reduces the processing speed

Method used

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  • Demodulation method of 16QAM in time division synchronized CDMA system
  • Demodulation method of 16QAM in time division synchronized CDMA system
  • Demodulation method of 16QAM in time division synchronized CDMA system

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Embodiment Construction

[0026] Such as image 3 As shown, for a received signal, the signal and its constellation coordinates are rotated 45 degrees clockwise. Let the corresponding mapping bit be b 0 b 1 b 2 b 3 , then first calculate b according to the rotated signal 0 possible log-likelihood ratio according to The maximum value of the calculation result is demodulated to b 0 ; Rotate the signal and its constellation diagram coordinates counterclockwise by 45 degrees, and calculate b according to the rotated signal 1 possible log-likelihood ratio according to The maximum value of the calculation result is demodulated to b 1 ; then according to b 0 , b 1 The demodulation result of demodulation b 2 , b 3 . The specific steps are described in detail below.

[0027] Let the received signal in the coordinates of the original constellation diagram be R(x, y), and the rotated one be R'(x', y'), where x' and y' represent the real part and the imaginary part of the signal respectively. ...

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Abstract

The invention discloses a 16QAM demodulation method in a time division synchronous code division multiple access system, comprising the steps of: rotating the received signal and the coordinates of the constellation diagram where it is located by 45 degrees clockwise, and calculating the possible logarithmic likelihood ratio  of b0 0, 0 takes the maximum value of the calculation results, if 0 is greater than 0, then b0 is 0, otherwise b0 is 1; rotate the aforementioned signal and the coordinates of the original constellation diagram counterclockwise by 45 degrees, and calculate b1 according to the aforementioned method; according to b0, The demodulation result of b1 adjusts the aforementioned signal, and calculates 2 and 3 according to 2=x+y, 3=y-x. If the calculation result is greater than 0, the demodulation result of the corresponding bit is 0; otherwise, the demodulation result is 1. The present invention adopts the combination of phase rotation and segmented function, demodulation soft judgment mode, realizes 16QAM soft demodulation conveniently, not only has less calculation amount, but also guarantees demodulation performance effectively, thereby improves 16QAM in TD-SCDMA system demodulation efficiency and quality.

Description

technical field [0001] The invention relates to a 16QAM (Quadrature Amplitude Modulation, quadrature amplitude modulation) demodulation method in a time division synchronous code division multiple access system in a 3G (third generation) communication system. Background technique [0002] With the increase of mobile multimedia services, the transmission rate of 2Mb / s of the third generation mobile communication system will not be able to meet the requirements, and it is inevitable to develop a mobile communication system with larger capacity and higher bit transmission rate. Therefore, WCDMA (Wideband Code Division Multiple Access, Wideband Code Division Multiple Access), CDMA2000 and TD-SCDMA (Time Division—Synchronous Code Division Multiple Access, Time Division Synchronous Code Division Multiple Access) are all undergoing technical enhancements to develop higher service rate, and provide more B3G (the last three generations of mobile communication) application services. ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04L27/38
Inventor 刘虎李颖傅强
Owner ZTE CORP
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