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Soft demodulation method and soft demodulation system applicable to QAM (Quadrature Amplitude Modulation) of Gray mapping

A technology of Gray mapping and soft demodulation, applied in the field of communication, which can solve the problem of high computational complexity

Active Publication Date: 2014-12-03
北京中科晶上科技股份有限公司
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Problems solved by technology

[0009] In order to solve the problem of high computational complexity in the existing soft demodulation technology, according to an embodiment of the present invention, a soft demodulation method suitable for Gray-mapped QAM is provided, the method includes:

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  • Soft demodulation method and soft demodulation system applicable to QAM (Quadrature Amplitude Modulation) of Gray mapping
  • Soft demodulation method and soft demodulation system applicable to QAM (Quadrature Amplitude Modulation) of Gray mapping
  • Soft demodulation method and soft demodulation system applicable to QAM (Quadrature Amplitude Modulation) of Gray mapping

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Embodiment Construction

[0056] In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below through specific embodiments in conjunction with the accompanying drawings. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

[0057] The existing soft demodulation methods ignore a problem when they are implemented, that is, the above-mentioned types of decoders do not require the soft demodulator to provide accurate LLR information. For example, the Turbo decoder only needs 5-bit quantized fixed-point LLR information to achieve almost the same decoding performance as floating-point LLR information, and the Viterbi decoder only needs 8-bit quantized LLR information to achieve almost the same decoding performance as floating-point LLR information. same decoding performance. Based on this, according to an embo...

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Abstract

The invention provides a soft demodulation method and a soft demodulation system applicable to QAM (Quadrature Amplitude Modulation) of Gray mapping. The method comprises the steps of acquiring a correction factor corresponding to each bit in currently received symbols; and calculating an LLR (Log-Likelihood Ratio) value corresponding to each bit according to the currently received symbols and the correction factor corresponding to each bit, thereby carrying out soft demodulation on the currently received symbols. The correction factor indicates a constellation pattern required to be demodulated and the current noise variance, and approaches the slope of a first-order linear function of an LLR theoretical curve of the corresponding bit. The soft demodulation method and the soft demodulation system can be applied to QAM of the Gray mapping, particularly can be applied to soft demodulation for high-order QAM, and can maintain the accuracy of acquired LLR information while reducing the computational complexity.

Description

technical field [0001] The present invention relates to the technical field of communication, more specifically, to a soft demodulation method and system suitable for Gray-mapped QAM, especially high-order QAM. Background technique [0002] Since the Gray-mapped QAM (Quadrature Amplitude Modulation, quadrature amplitude modulation) modulation method can provide lower bit error rate performance, and the complexity of soft demodulation is relatively simple compared with other modulation methods of the same order, so This type of modulation has received much wider attention. For example, 64QAM has been applied in communication protocols such as HSPA+ and LTE, and 256QAM, which can provide higher spectral efficiency, will also be introduced into the latest wireless LAN protocol IEEE 802.11ac. [0003] When demodulating QAM-modulated symbols, high-order QAM will lead to high computational complexity. In the past, the channel decoder basically used the hard decoding method, that...

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Application Information

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IPC IPC(8): H04L1/00H04L27/34
Inventor 苏泳涛姚彦斌林江南石晶林
Owner 北京中科晶上科技股份有限公司
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