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Demodulation method of 16QAM in time division synchronized CDMA system

A code division multiple access and time division synchronization technology, applied in multi-carrier systems and other directions, can solve the problems of increasing processor overhead, large calculation amount, and reducing processing speed, achieving less calculation amount, ensuring demodulation performance, and improving demodulation. The effect of efficiency

Inactive Publication Date: 2005-11-16
ZTE CORP
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AI Technical Summary

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

[0022] 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 ratios 0 , according to  0 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 ratios 1 , according to  1 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.

[0023] 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...

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Abstract

The method includes steps: (1) rotating the received signal and relevant coordinate of planisphere 45 degree in clockwise; (2) calculating b0' possible log likelihood ratio of b0, b0' takes maximum of calculated values; if b0' is larger than 0, then b0 = 0; otherwise b0 = 1; (3) rotating the received signal and relevant coordinate of planisphere 45 degree in anticlockwise, and calculating b1 according to the method; based on results of b0 and b1, adjusting the signals above; (4) calculating b2' and b3' according to b2' = x+y, b3' = y - x; if calculated result is larger than 0, then demodulated result of corresponding bit is 0, otherwise, demodulated result is 1. Features are simple, less amount of calculation, ensuring demodulation performance effectively so as to raise demodulating efficiency and quality of 16 QAM in TD - SCDMA system.

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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IPC IPC(8): H04L27/38
Inventor 刘虎李颖傅强
Owner ZTE CORP
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