Quadrature amplitude modulation qubit demodulation method and device

Abstract

The embodiment of the invention discloses a quadrature amplitude modulation qubit demodulation method. The method includes the steps of predetermining a sub-area which each constellation point belongs to on a gray constellation complex plane corresponding to a bit position to be demodulated, wherein each sub-area corresponds to a perpendicular bisector; determining a sub-area which each constellation point containing the corresponding bit position to be demodulated and mapped by a received symbol on the gray constellation complex plane corresponding to the bit position to be demodulated; calculating the perpendicular distance between each received symbol containing the corresponding bit position to be demodulated and the corresponding perpendicular bisector, and making the distances serve as the qubit values of the bit position to be demodulated, wherein the qubit values are positive when each received symbol containing the corresponding bit position to be demodulated is located on the side, with the first bit value, of the corresponding perpendicular bisector, and the qubit values are negative when each received symbol containing the corresponding bit position to be demodulated is located on the side, with the second bit value, of the corresponding perpendicular bisector. The invention further discloses a quadrature amplitude modulation qubit demodulation device. By means of the quadrature amplitude modulation qubit demodulation method and device, the qubit demodulation efficiency can be improved.

Description

technical field [0001] The present application relates to the field of communication technology, in particular to a quadrature amplitude modulation (QAM) soft bit demodulation method and a corresponding device. Background technique [0002] In order to improve spectrum utilization, modern communication systems usually adopt high-order modulation. Quadrature Amplitude Modulation (Quadrature Amplitude Modulation, QAM) is a commonly used high-order modulation method, and since its modulation order M can be 4, 8, 16, 32, it can also reach 128, 256 or more. After adopting quadrature amplitude modulation, its decoding system usually adopts BICM (Bit-Interleaved Coded Modulation) of soft decision decoding. This decoding method requires the demodulator to output soft bit information. Soft bit information is usually measured by the Log-Likelihood Ratio (LLR) of the received bits, namely: [0003] LLR ( b ) = ...

AI Technical Summary

Problems solved by technology

Although this demodulation method no longer performs complex exponential operations, it still needs to calculate the distance between the received symbol and each constellation point in the Gray constellation diagram. The higher the order of quadrature amplitude modulation, the higher the constellation point on the Gray constellation The more bits, the amount of calculation will increase exponentially, prolonging the processing time, thereby reducing the efficiency of demodulating soft bit information

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