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Code modulation method, demodulation and decoding method and system

A coding modulation and coding technology, which is applied in the field of digital information transmission, can solve the problems of insufficient robustness of channel conditions, low code rate, and unsatisfactory performance, and achieve the effects of reducing Shaping loss, increasing diversity order, and improving throughput

Active Publication Date: 2013-06-12
TSINGHUA UNIV
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  • Abstract
  • Description
  • Claims
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AI Technical Summary

Problems solved by technology

[0015] Existing communication and broadcasting systems usually use BICM technology, and its coding and modulation parts are independent of each other. Although TCM technology combines coding and modulation technology for optimization, the performance in fading channels is not good.
The BICM-ID technology proposed by the academic circle is a good combination of coding and modulation technology, but the existing BICM-ID technology has many weaknesses, so it is not conducive to be applied to industrial standards
For example, the traditional BICM-ID has a high bit error platform, because it requires high-order mapping, it needs to use an outer code with a very low code rate when the spectral efficiency is low, and the robustness to channel conditions is not enough. For example, a well-designed AWGN channel BICM-ID systems often perform unsatisfactorily in fading channels

Method used

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  • Code modulation method, demodulation and decoding method and system

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Embodiment 1

[0100] like image 3 As shown, in order to reduce the Shaping loss of the BICM and BICM-ID systems, the encoding and modulation method according to an embodiment of the present invention in this embodiment includes:

[0101] S1. Perform channel coding and bit interleaving on the input information bits to obtain coded bits;

[0102] S2. Perform M-point APSK constellation mapping on the coded bits, where M is a positive integer greater than 1.

[0103] APSK is a Gaussian-like constellation map of complex space. Using the two degrees of freedom of amplitude and phase, this embodiment can well approach the ideal Gaussian distribution by optimizing the distribution of APSK constellation points, thereby effectively reducing the Shaping loss, and finally obtaining transmission performance close to the channel capacity.

[0104] Similar to traditional QAM constellation mapping, APSK constellation diagrams with different numbers of points need to be designed for different spectrum ef...

Embodiment 2

[0110] The MAPSK in embodiment 1 has an obvious effect on reducing the Shaping loss when the spectral efficiency is high, but the effect is limited when the spectral efficiency is low. The reason is that the coded modulation system with low spectral efficiency usually adopts low-order modulation with very small M, such as M=8 or 4, and the distribution of constellation points is difficult to approach the ideal Gaussian distribution, and the Shaping loss at this time is inherently small. In addition, Constellation point mapping methods are also limited.

[0111] In order to effectively reduce Shaping losses under various spectral efficiencies, the coding and modulation method of this embodiment is especially suitable for coding and modulation systems with low spectral efficiency, and also suitable for coding and modulation systems with medium and high spectral efficiencies.

[0112] like Figure 6 As shown, it is a flowchart of a coding and modulation method according to an im...

Embodiment 3

[0122] The channel coding and constellation mapping of BICM and BICM-ID systems are designed and optimized for memoryless channels. The purpose of making the channel memoryless is to maximize the diversity order of the coding modulation system and the demodulation decoding system, which is very important for transmission in fading channels. Due to the use of bit interleaving technology, the input of channel decoding at the receiving end can be equivalent to a memoryless input, which is also the advantage of BICM and BICM-ID systems.

[0123] In order to ensure the transmission performance of BICM and BICM-ID systems in fading channels, the input of constellation demapping at the receiving end must also be optimized to the greatest extent. Therefore, the encoding and modulation method of this embodiment proposes constellation rotation technology and a general-purpose method combined with dimension conversion. Real number interleaving technology, together with BICM and BICM-ID t...

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Abstract

The invention relates to a code modulation method, demodulation and decoding method and system which are used for digital communication systems. The code modulation method comprises the following steps of: carrying out channel coding and bit interleaving on an input information bit to obtain a code bit; and carrying out M-point K-dimensional Gaussian constellation mapping on the code bit to obtain a constellation mapping symbol, i.e. a K-dimensional real number vector, wherein M and K are both integers more than 1. The method and the system can ensure that the performances of a code modulation system and a corresponding demodulation and decoding system approach channel capacity in high and low frequency spectrums under the condition of a plurality of channels, such as AWGN (Additive WhiteGaussian Noise), attenuation and the like, and consider the throughput capacity of the system at the same time.

Description

technical field [0001] The invention relates to the field of digital information transmission, in particular to a bit interleaving coding and modulation method, demodulation and decoding method and system in a digital communication system. Background technique [0002] One of the fundamental tasks of digital communication systems, including typical wireless mobile communication systems and terrestrial digital broadcasting systems, is to realize the error-free transmission of digital information. Using channel coding for error control is the most effective method and means to realize this fundamental task. In order to meet the transmission requirements of digital information on common analog channels, channel coding technology usually needs to be combined with digital modulation technology. The combination of channel coding and modulation constitutes a coded modulation system, which is a subsystem of the digital communication system transmitter and one of its core modules, a...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04L1/00H04L27/34H04L27/38
Inventor 杨知行谢求亮彭克武宋健王昭诚
Owner TSINGHUA UNIV
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