Unconditional secure communication method based on beam-forming and security code

• US 9,985,986 B2
• Filed: 06/26/2015
• Issued: 05/29/2018
• Est. Priority Date: 06/19/2015
• Status: Active Grant

• Current Assignee: University of Electronic Science and Technology of China
• Original Assignee: University of Electronic Science and Technology of China
• Inventors: Wen, Hong, Tang, Jie, Xiang, Da, Song, Huanhuan
• Primary Examiner(s): Shiferaw, Eleni A
• Assistant Examiner(s): Holmes, Angela R
• Application Number:
  US15/306,094
• Publication Number:
  US 20170149823A1
• Time in Patent Office: 1,068 Days
• Field of Search: 726 26
• CPC Class Codes: H04B 7/0456 Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04L 1/06 using space diversity
• CPC Class Codes: H04L 63/0428 wherein the data content is protected, e.g. by encrypting or encapsulating the payload
• CPC Class Codes: H04L 63/1475 Passive attacks, e.g. eavesdropping or listening without modification of the traffic monitored
• CPC Class Codes: H04L 9/0875 based on channel impulse response [CIR]
• CPC Class Codes: H04W 12/122 Counter-measures against attacks; Protection against rogue devices

Abstract

The present invention discloses an unconditional secure communication method based on beam-forming and security code, which comprises the following steps of: Legitimate users send to the signal pie-encoded and modulated, meanwhile eavesdropper receives signals and calculates the bit error rate; computing security coding parameters, legitimate received users send pilot sequence, and legitimate sending users estimate legitimate channel, and extract information on legal channel coding and modulating signal was SVD pre-coding and sending; the signal was decoded, that will be judgment and demodulation then the signal after decoding do security code is transmitted to message or tapping, due to lack of legal channel information, eavesdropper cannot lift pre-coding processing of the received signal with the high bit error rate. This method can establish advantages channel of the wiretap model channel and to ensure that legitimate users can receive signals at the lower bit error rate.

Claims

1. An unconditional secure communication method based on beam-forming and security code, comprising steps of:

S1;

a legitimate receiver sending a pilot sequence Reference Signal (RS) to a legitimate transmitter, the RS going through a legitimate channel and an eavesdropping channel respectively, the legitimate transmitter and a passive eavesdropper receiving the RS, where a legitimate channel matrix is H1 and an eavesdropper'"'"'s channel matrix is H2;

S2;

the legitimate transmitter receiving a pilot sequence Y_RS which is transmitted by the legitimate receiver, where the pilot sequence Y_RS is obtained by the pilot sequence RS which is Rayleigh decayed through the legitimate channel, that is;

Y_RS=H1*RS+n 

 

(1)

applying Least Square (LS) algorithm to get uplink channel estimation value H_esti;

H_esti=Y_RS*RS<sup>−

1</sup> 

 

(2)

then transposing the H_esti, that is (H_esti)^T=H1esti;

S3;

modulating a plurality of bits X′

_bits which is sent by transmitter, and getting the complex modulated symbols X′

;

S4;

extracting Channel State Information (CSI) from H1esti, that is do Singular Value Decomposition (SVD) with H1esti;

H1esti=UDV^H 

 

(3)

then getting the V as the vector corresponding to the largest singular value getting the pre-coding matrix W;

S5;

doing SVD pre-coding processing for X′

, then getting W*X′

, and sending out a pre-coded signal W*X′

;

S6;

a pre-coded signal going through the legitimate channel and eavesdropping channel, and it is received by the legitimate receiver and the eavesdropping receiver respectively, in which the legitimate receiver receives signal as Y1′

;

Y1′

=H1*WX′

+n1 

 

(4)

the eavesdropper receiving signal as Y2;

Y2′

=H2*WX′

+n2 

 

(5)

S7;

the legitimate receiver and the eavesdropper to recover the secret bit through signal decision and decoding respectively;

in receiving side, the legitimate receiver doing MMSE decoding on Y1′

by multiply matrix He=H1*W;

X1′

=(He<sup>−

1</sup>He+I*σ

²)<sup>−

1</sup>He<sup>−

1</sup>*Y1′

 

 

(6)

then doing decision and demodulated on X1′

, getting bits streams X′

_bits1, then computing the bit error rate BER1′

according to X′

_bits;

in receiving side, eavesdropper also doing Minimum Mean Square Error (MMSE) decoding on Y2′

by multiply matrix HE=H2*W;

X2′

=(HE<sup>−

1</sup>HE+I*σ

<sup>−

2</sup>)<sup>−

1</sup>HE<sup>−

1</sup>*Y2′

 

 

(7)

then doing decision and demodulated on X2′

, getting bits streams X′

_bits2, then computing the bit error rate BER2′

according to X′

_bits ;

S8;

getting the parameters of secret code and choose the proper codes based on BER2′

;

S9;

the transmitter encoding the secret bits X_bits by the secure code, then modulating and getting the complex signal X, and sending W*X signal which is pre-coded by transmitter;

S10;

after the legitimate transmitter sending out the preprocessed signal, the preprocessed signal going through a legitimate channel and a eavesdropping channel, and which is received by the legitimate receiver and eavesdropping receiver, in which the legitimate receiver getting the signal Y1;

Y1=H1*WX+n3 

 

(8)

and the eavesdropper receiver get signal Y2;

Y2=H2*WX+n4 

 

(9)

S11;

in receiving side, the legitimate receiver and eavesdropper to recovery the secret bits through signal decision and decoding, respectively;

legitimate receiver doing MMSE decoding on Y1 by multiply matrix He=H1*W;

X1=(He<sup>−

1</sup>He+I*σ

²)<sup>−

1</sup>He<sup>−

1</sup>*Y1 

 

(10)

then doing decision and demodulated on X1, getting bits stream X_bits1, doing secure decoding on X_bits1, getting the secret bits;

eavesdropper also doing MMSE decoding on Y2 by multiply matrix HE=H2*W;

X2=(HE<sup>−

1</sup>HE+I*σ

²)<sup>−

1</sup>HE<sup>−

1</sup>*Y2 

 

(11)

Finally, the eavesdropper doing decision and demodulated on X2, getting bits stream X_bits2, then do secure decoding on X_bits2, get the eavesdropping secret bits;

the n, n1, n2, n3, n4 are Gaussian white noise, I is unit matrix, and σ

is the variance of Gaussian white noise;

the eavesdropper are unknown the channel information on H1, the bit error rate will be high after processing the received pre-coded signal.

2. The unconditional secure communication method based on beam-forming and security code according to claim 1, wherein the modulating ways in step S3, step S7 and step S11 is one of 16 QAM (Quadrature Amplitude Modulation), 64QAM, QPSK (Quadrature Phase Shift Keyin), 8PSK (Phase-Shift Keying) and BPSK (Binary Phase Shift Keying).

3. The unconditional secure communication method based on beam-forming and :

security code according to claim 1,

wherein the decision in step S7 and step S11 is as the soft decision.