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Method for reducing safety gap of COFDM system

A technology of safety circle and constellation point, which is applied in the field of reducing the safety circle of COFDM system, can solve the problems of large safety circle, low signal-to-noise ratio, narrowing of the safety circle, etc., and achieve less restrictions, good safety performance, and reduce the system safety circle Effect

Inactive Publication Date: 2016-11-30
NORTHWEST UNIV
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Problems solved by technology

[0003] From the perspective of modulation mapping, the existing technology designs an inverse gray code (Yarg code) with the goal of maximizing the distance between adjacent constellation points, which improves the demodulation of low signal-to-noise ratio (Signal Noise Ratio, SNR) areas The bit error rate achieves the purpose of narrowing the security circle, which is simple to implement and has achieved good results, but the corresponding security circle is still relatively large, and the security circle has not been analyzed in the context of a complete communication system.

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  • Method for reducing safety gap of COFDM system
  • Method for reducing safety gap of COFDM system
  • Method for reducing safety gap of COFDM system

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Embodiment 1

[0037] This embodiment takes the 16QAM (Quadrature Amplitude Modulation) constellation modulation mode as an example to describe in detail the specific method for reducing the security margin of the C-YP-OFDM system.

[0038] Step 1, the information source outputs the information bit stream X(k), uses the FEC encoder to perform channel coding on X(k), and obtains the codeword sequence c(k);

[0039] Step 2: Perform inverse Gray code mapping on the codeword sequence c(k) to obtain the complex symbol sequence C(k), construct a 4-bit inverse Gray code, and map it to the constellation map to form a 16QAM inverse Gray code constellation map , specifically as figure 2 shown.

[0040] Step 3: Select the punctured constellation point Q for the complex symbol sequence C(k) according to the 16QAM inverse Gray mapping constellation diagram w Perform constellation punching and zeroing and output symbol sequence C p (k);

[0041] Will figure 2 Each constellation point in corresponds...

Embodiment 2

[0055] Choose LDPC code as the forward error correction code to form the LDPC-YP-COFDM security system, specifically select the QC-LDPC code defined in the 802.16e standard and the RU fast coding algorithm, and the decoding scheme uses Log -BP joint decoding algorithm, the LDPC code length is 2304, the code rate is 1 / 2, the number of decoding iterations is 10, the number of subcarriers of OFDM is 576, and the 16QAM constellation modulation method is selected. The recovery threshold ε under this constellation mapping is 0.1.

[0056] For various constellation mapping methods, the constellation diagrams are symmetric. Therefore, when each constellation point with the same Euclidean distance is selected as the perforated constellation point, the result of the security boundary is the same. Therefore, this Embodiment random from the constellation point candidate set {Q with the largest Euclidean distance 1 ,Q 4 ,Q 13 ,Q 16} select Q 16 When the constellation point is used as ...

Embodiment 3

[0061] The existing representative three security methods, a: perforated LDPC security coding method (see literature [1] for specific methods, Klinc D., Ha J., Mclaughlin S.W., et al.LDPC codes for physical layer security[ J].University of Windsor,2009), b: add disturbance matrix method (see literature [2] for specific methods, Baldi M., Bianchi M., Chiaraluce F..Non-systematic codes for physical layersecurity[C] / / Information Theory Workshop (ITW), 2010IEEE.IEEE, 2010:1-5), c: Inverse Gray code mapping method (see literature [3] for specific methods, Kwak B.J., Song N.O., Park B., et al.PhysicalLayer Security with Yarg Code[C] / / Proceedings of the 2009First International Conference on Emerging Network Intelligence.IEEE Computer Society, 2009:43-48) and the traditional LDPC-COFDM system were compared with the C-YP-COFDM algorithm of the present invention, and the specific results are shown in Table 2. Among them, both methods a and b are designed to reduce the system security bo...

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Abstract

The invention belongs to the technical field of communication safety, and specifically discloses a method for reducing a safety gap of a COFDM system. The method is based on a complete communication system environment, an information bit stream is output at a source of an emission end, channel encoding, Yarg-code mapping, constellation puncturing, serial-parallel conversion, inverse fast Fourier transform, parallel-serial conversion and CP adding operation are carried out on the information bit stream, a receiving end employs an algorithm opposite to the emission end, and finally, the information bit stream is recovered. According to the invention, a Yarg-code mapping method and a constellation puncturing technology are combined and are applied to a COFDM system, through performing puncturing zero-setting on constellation points on a Yarg-code constellation mapping graph, puncture positions are enabled to be not easily recovered under a signal-to-noise ratio and can be completely recovered under a high signal-to-noise ratio, the system bit error rate is enabled to be higher under the low noise-to-signal ratio and is more rapidly reduced under the high signal-to-noise ratio, and thus the purpose of greatly reducing the system safety gap is realized.

Description

technical field [0001] The invention belongs to the technical field of communication security, and in particular relates to a method for reducing the security boundary of a COFDM system. Background technique [0002] Orthogonal Frequency Division Multiplexing (OFDM) technology, as a multi-carrier modulation technology, has incomparable advantages in high-speed transmission systems. Coded Orthogonal Frequency Division Multiplexing (COFDM) is the core technology of broadband wireless communication, and effectively reducing its security margin is an important way to ensure secure communication. The security of digital communication system refers to whether the communication system has the capability of secure communication and the level of security. As a new wireless security transmission technology, physical layer security provides a new idea to solve the information security problem of wireless communication from the perspective of the physical layer at the bottom of the net...

Claims

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Application Information

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IPC IPC(8): H04J13/00H04J13/12H04L27/26
CPCH04J13/0014H04J13/12H04L27/2602
Inventor 高宝建景利杨育华黄士亚汪俊
Owner NORTHWEST UNIV
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