CN107994934B - Safe transmission method of untrusted relay network based on symbol separation and beam forming - Google Patents

Safe transmission method of untrusted relay network based on symbol separation and beam forming Download PDF

Info

Publication number
CN107994934B
CN107994934B CN201711118285.9A CN201711118285A CN107994934B CN 107994934 B CN107994934 B CN 107994934B CN 201711118285 A CN201711118285 A CN 201711118285A CN 107994934 B CN107994934 B CN 107994934B
Authority
CN
China
Prior art keywords
relay
relays
equal
noise
matrix
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN201711118285.9A
Other languages
Chinese (zh)
Other versions
CN107994934A (en
Inventor
姚如贵
蒋朋飞
陆亚南
左晓亚
徐娟
马科维
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Northwestern Polytechnical University
Shenzhen Institute of Northwestern Polytechnical University
Original Assignee
Northwestern Polytechnical University
Shenzhen Institute of Northwestern Polytechnical University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Northwestern Polytechnical University, Shenzhen Institute of Northwestern Polytechnical University filed Critical Northwestern Polytechnical University
Priority to CN201711118285.9A priority Critical patent/CN107994934B/en
Publication of CN107994934A publication Critical patent/CN107994934A/en
Application granted granted Critical
Publication of CN107994934B publication Critical patent/CN107994934B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/0413—MIMO systems
    • H04B7/0456—Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/022—Site diversity; Macro-diversity
    • H04B7/026—Co-operative diversity, e.g. using fixed or mobile stations as relays
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
    • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
    • H04B7/0617—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal for beam forming
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/08—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station
    • H04B7/0837—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station using pre-detection combining
    • H04B7/0842—Weighted combining
    • H04B7/086—Weighted combining using weights depending on external parameters, e.g. direction of arrival [DOA], predetermined weights or beamforming

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)
  • Radio Relay Systems (AREA)

Abstract

The invention provides a safe transmission method of an untrusted relay network based on symbol separation and beam forming, which comprises the steps of selecting two relays with strongest channel gains to respectively send a real part and an imaginary part of useful symbol separation, then designing directional beam forming, and enabling the two selected relays to receive the real part and the imaginary part of a useful signal to the maximum extent so as to ensure that an untrusted relay node R cannot eavesdrop useful information, and simultaneously enabling a target node R to receive the real part and the imaginary part of the useful signal
Figure DDA0001466787120000011
Useful information can be decoded, so that the safe transmission performance of the network is improved. The method improves the reliability of network transmission while minimizing the decoding capability of the untrusted relay, and has important significance for improving the safe transmission performance of the system.

Description

Safe transmission method of untrusted relay network based on symbol separation and beam forming
Technical Field
The invention relates to a safe transmission method of an untrusted relay network.
Background
In recent years, due to the openness of wireless communication, wireless signals are easily intercepted, tampered and interfered, so that a great threat is brought to the secure communication of users, and the security problem of wireless networks is receiving more and more attention. Unlike conventional encryption mechanisms, Physical-Layer Security (Physical-Layer Security) has the advantages of lower computational complexity and saving time and spectrum resources. As the security of wireless communication is more and more improved, physical layer security has gained wide attention in both theoretical research and practical applications.
With the shortage of communication resources and the development of relay selection technology, the introduction of relay selection technology into the physical layer security model has attracted more and more attention. In an actual application system, how to select an optimal relay from a plurality of potential relays, thereby effectively utilizing system resources, improving the Bit Error Rate (BER) performance of the system and optimizing the network performance becomes a problem of concern. If the relay node itself is not trusted, it becomes more complicated how to design an efficient secure transmission scheme. Therefore, for the application scenarios of multiple antennas and multiple untrusted relays, a safe transmission scheme design based on symbol separation and beam forming is developed, which has important significance for improving system safety and improving system error rate.
Document 1, "Spectral efficiency protocols for half-duplex decoding relays [ IEEE Journal on Selected Areas in Communications, vol.25, No.2, pp.379-389,2007 ]" aims at an authentic relay network to obtain a conclusion that cooperative relaying can improve the reachable rate of a system, and proposes a bidirectional relay transmission scheme, which can complete information exchange between two source nodes in two time slots, thereby effectively improving the spectrum efficiency.
Document 2 "On the roaming power allocation for secure amplification and forwarding of wireless communication in a two-hop wireless relay network with an eavesdropping node" discusses secure communication in the two-hop wireless relay network. In order to prevent an eavesdropper from intercepting useful information, the destination node sends interference noise, which is beneficial to protecting the source information from eavesdropping and simultaneously ensuring reliable decoding by the destination node.
Document 3 "Cooperation with an undirected relay: a secret permanent [ ieee transactions on Information Theory, vol.56, No.8, pp.3807-3827,2009 ]" for a single-antenna unidirectional untrusted relay network, it is demonstrated that using a target cooperative interference (DJ) scheme for using an untrusted relay node in communication results in a higher achievable safe rate than simply treating it as an eavesdropping node.
Document 4 "Secure beamforming for MIMO two-way communications with undirected Relay [ IEEE Transactions on Signal Processing, vol.62, No.9, pp.2185-2199,2014 ]" mainly studies the beam forming design in a multi-antenna, single Relay system, with the help of an untrusted Relay node, the source node and the destination node exchanging messages. The relay node is used as a signal repeater and a potential eavesdropper, and the safety rate of the system can be obviously improved by utilizing the beam forming technology.
Document 5 "Robust beamforming for correlation in MIMO wireless channels with pilot CSI [ IEEE Transactions on Signal Processing, vol.59, No.1, pp.351-361,2011 ]" mainly studies that a source node sends Artificial Noise (AN) to interfere with untrusted relay and eavesdrop useful information under high channel gain, and equal power distribution is performed on cooperative interference signals and useful signals, so that higher security can be achieved.
Document 6, "Relay selection for secure communication networks with undirected nodes [ IEEE Transactions on Signal Processing, vol.11, No.11, pp.2466-2476,2016 ]" mainly studies that a target node sends a cooperative interference Signal, so as to avoid an untrusted Relay node from stealing useful information, thereby improving the security of a physical layer.
Currently, related to the research on the physical layer security technology is mainly to develop an optimization design for eavesdropping nodes, and a relay network itself is trusted (as in documents 1 and 2), while research on an untrusted relay system is very little. Next, the existing research is mainly directed to the case where the source and the sink are single antennas (see document 3). Furthermore, the existing research mainly aims at the beamforming technology of the single relay network (as in document 4). In addition, the existing documents mainly study the cooperative interference at the source node or the destination node to improve the physical layer safety (as documents 5 and 6), but part of the transmission power is wasted.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a safe transmission method of an untrusted relay network based on symbol separation and beam forming, which is optimally designed from the angles of a safe transmission scheme, relay selection, symbol separation, beam forming and the like, effectively reduces the capability of the untrusted relay for decoding useful information, improves the transmission reliability of the whole communication link, and realizes information safe transmission under the application scene of multiple antennas and multiple untrusted relays by utilizing the physical layer safety technology.
The technical scheme adopted by the invention for solving the technical problem comprises the following steps:
step one, in a first time slot of an information transmission process, completing relay selection, precoding design, symbol separation and beam forming, specifically comprising the following contents:
(1) for a source node
Figure BDA0001466787100000021
N untrusted relay nodes
Figure BDA0001466787100000022
And a destination node
Figure BDA0001466787100000023
Formed multi-antenna, multi-untrusted relay network, assuming
Figure BDA0001466787100000031
Is provided with L antennas, and the L antennas are arranged,
Figure BDA0001466787100000032
z antennas are arranged, all relays are single antennas, L is more than or equal to N and more than or equal to 2,
Figure BDA0001466787100000033
and
Figure BDA0001466787100000034
there is no direct transmission link between them, allThe nodes all work in a half-duplex mode, and all the nodes receive noise with the mean value of 0 and the variance of N0Additive complex gaussian noise of (1); channel vector according to ith relay
Figure BDA00014667871000000351
Two relays with the strongest channel gain are selected
Figure BDA0001466787100000035
And
Figure BDA0001466787100000036
wherein i is more than or equal to 1, m, N is more than or equal to N, and m is not equal to N;
(2) definition except for
Figure BDA0001466787100000037
To
Figure BDA0001466787100000038
And from
Figure BDA0001466787100000039
To
Figure BDA00014667871000000310
The channel matrixes of all other relays are respectively
Figure BDA00014667871000000311
And
Figure BDA00014667871000000312
Figure BDA00014667871000000313
obtained by singular value decomposition
Figure BDA00014667871000000355
Wherein,
Figure BDA00014667871000000314
is composed of
Figure BDA00014667871000000315
A diagonal matrix of all the singular values,
Figure BDA00014667871000000316
and
Figure BDA00014667871000000317
is a unitary matrix; decomposing matrix V to obtain V ═ V1V2]Wherein
Figure BDA00014667871000000318
And V is2The column of (a) is a subspace of (b)
Figure BDA00014667871000000319
A null space of (a); suppose that
Figure BDA00014667871000000320
Representation matrix V2J is more than or equal to 1 and less than or equal to L-N +1, and designing precoding vectors
Figure BDA00014667871000000321
In the same way, obtain and
Figure BDA00014667871000000322
of the orthogonal basis matrix
Figure BDA00014667871000000323
Figure BDA00014667871000000324
Representation matrix T2K is more than or equal to 1 and less than or equal to L-N +1, and designing precoding vectors
Figure BDA00014667871000000325
(3)
Figure BDA00014667871000000326
Mapping a bit stream into one using M-ary modulation techniquesComplex signal of unit power
Figure BDA00014667871000000352
Wherein
Figure BDA00014667871000000327
And
Figure BDA00014667871000000328
are respectively complex signals
Figure BDA00014667871000000329
Real and imaginary parts of, constructed using symbol separation techniques and beamforming techniques
Figure BDA00014667871000000330
Is sent out
Figure BDA00014667871000000331
Wherein,
Figure BDA00014667871000000332
Psto represent
Figure BDA00014667871000000333
The transmission power of (a); at the selection of
Figure BDA00014667871000000334
And
Figure BDA00014667871000000335
the positions respectively receive the real part and the imaginary part of a useful signal and superpose additive complex Gaussian noise, other unselected relays can only receive the additive complex Gaussian noise, and the signals received by the relay nodes are expressed as
Figure BDA00014667871000000336
Wherein,
Figure BDA00014667871000000337
is shown in
Figure BDA00014667871000000338
Processing the received additive complex gaussian noise;
step two, in a second time slot of the information transmission process, completing relay amplification forwarding, source node cooperative interference and combined reception, wherein the specific contents are as follows:
(1) selected relay
Figure BDA00014667871000000339
And
Figure BDA00014667871000000340
amplifying the forwarded signal to
Figure BDA00014667871000000353
And
Figure BDA00014667871000000354
wherein, mumAnd mumTo represent
Figure BDA00014667871000000341
And
Figure BDA00014667871000000342
the amplification factor of (a) is,
Figure BDA00014667871000000343
and
Figure BDA00014667871000000344
Figure BDA00014667871000000345
and
Figure BDA00014667871000000346
is composed of
Figure BDA00014667871000000347
And
Figure BDA00014667871000000348
the transmit power of (a);
(2) by the source node
Figure BDA00014667871000000349
Sending artificial noise to all relay nodes;
(3) in that
Figure BDA00014667871000000350
To the received signal
Figure BDA0001466787100000041
Wherein,
Figure BDA0001466787100000042
is that
Figure BDA0001466787100000043
Total equivalent noise; by means of the method of regular inversion,
Figure BDA0001466787100000044
to decode useful information
Figure BDA00014667871000000424
Is estimated value of
Figure BDA0001466787100000045
Wherein,
Figure BDA0001466787100000046
and
Figure BDA0001466787100000047
respectively represent
Figure BDA0001466787100000048
And
Figure BDA0001466787100000049
is determined by the estimated value of (c),
Figure BDA00014667871000000410
is that
Figure BDA00014667871000000411
And
Figure BDA00014667871000000412
the equivalent channel matrix in between is used,
Figure BDA00014667871000000413
the invention has the beneficial effects that: aiming at the problem of safe transmission of an untrusted multi-relay network, a safe transmission scheme based on symbol separation and beam forming is provided, the decoding capability of an untrusted relay is minimized, meanwhile, the reliability of network transmission is improved, and the method has important significance for improving the safe transmission performance of a system.
Drawings
FIG. 1 is a diagram of a multi-antenna, multi-untrusted relay network communication model;
fig. 2 is a comparison of error rate performance at the relay node and at the destination node for different schemes.
Detailed Description
The present invention will be further described with reference to the following drawings and examples, which include, but are not limited to, the following examples.
The invention provides a novel safe transmission scheme of an untrusted relay network based on symbol separation and beam forming, which comprises the steps of selecting two relays with strongest channel gains to respectively send a real part and an imaginary part of useful symbol separation, then designing directional beam forming, and enabling the two selected relays to receive the real part and the imaginary part of a useful signal to the maximum extent so as to ensure that an untrusted relay node R cannot eavesdrop useful information, and simultaneously enabling a target node R to receive the real part and the imaginary part of the useful signal
Figure BDA00014667871000000414
Useful information can be decoded, so that the safe transmission performance of the network is improved.
In the invention, the relay network is not trusted and can eavesdrop useful information. In the invention, a single antenna is expanded to a multi-antenna research, multiple relays are selected, corresponding beam forming precoding is designed, a safety scheme design based on the combination of symbol separation and beam forming is developed from another angle aiming at the application scenes of multiple antennas and multiple untrusted relays, signals are divided into a real part and an imaginary part to be respectively transmitted, and useful signals are sent to the best relay to be amplified and forwarded by utilizing a beam forming technology, so that the error rate of a system is reduced while the safety is improved.
The channel model studied by the invention is a multi-antenna multi-untrusted relay network with three nodes, and the communication principle of the relay network is shown in fig. 1. The model consists of a source node
Figure BDA00014667871000000415
N untrusted relay nodes
Figure BDA00014667871000000416
And a destination node
Figure BDA00014667871000000417
And (4) forming. Suppose that
Figure BDA00014667871000000418
Is provided with L antennas, and the L antennas are arranged,
Figure BDA00014667871000000419
and all relays are single-antenna and L is more than or equal to N and more than or equal to 2. Due to the long-distance transmission or the shadow effect,
Figure BDA00014667871000000420
and
Figure BDA00014667871000000421
there is no direct link between them, so
Figure BDA00014667871000000422
And
Figure BDA00014667871000000423
can only pass through
Figure BDA0001466787100000051
Communication is performed. In the present invention, it is assumed that all nodes operate in half-duplex mode, and that all nodes receive noise with mean 0 and variance N0Additive complex gaussian noise.
The technical scheme adopted by the invention for solving the technical problem comprises the following steps:
step one, in a first time slot of an information transmission process, respectively completing operations such as relay selection, precoding design, symbol separation, beam forming and the like:
(1) and (4) relay selection. According to channel vector
Figure BDA0001466787100000052
Selecting the channel with the strongest gain, i.e.
Figure BDA0001466787100000053
(||·||22 norm representing vector) of the maximum two relays
Figure BDA0001466787100000054
And
Figure BDA0001466787100000055
wherein i is more than or equal to 1, m, N is more than or equal to N, and m is not equal to N,
Figure BDA0001466787100000056
represents from
Figure BDA0001466787100000057
The channel vector to the i-th relay,
Figure BDA0001466787100000058
and
Figure BDA0001466787100000059
respectively representing the mth and nth relays.
(2) Precoding vectors
Figure BDA00014667871000000510
And
Figure BDA00014667871000000511
and (5) designing. Define from
Figure BDA00014667871000000512
To
Figure BDA00014667871000000513
To and from
Figure BDA00014667871000000514
To
Figure BDA00014667871000000515
The channel matrixes of all other relays are respectively
Figure BDA00014667871000000516
And
Figure BDA00014667871000000517
can be expressed as
Figure BDA00014667871000000518
Obtained by singular value decomposition
Figure BDA00014667871000000519
Wherein,
Figure BDA00014667871000000520
is composed of
Figure BDA00014667871000000521
A diagonal matrix of all the singular values,
Figure BDA00014667871000000522
and
Figure BDA00014667871000000523
is a unitary matrix. Further decomposing the matrix V may result in V ═ V1V2]Wherein
Figure BDA00014667871000000524
And V is2The column of (a) is a subspace of (b)
Figure BDA00014667871000000525
Of zero space, i.e.
Figure BDA00014667871000000526
Suppose that
Figure BDA00014667871000000527
Representation matrix V2Is 1 < j < L-N +1), the invention maximizes
Figure BDA00014667871000000528
To maximize reception and thereby design precoding vectors
Figure BDA00014667871000000529
Namely, it is
Figure BDA00014667871000000530
In the same way, can obtain
Figure BDA00014667871000000531
Of the orthogonal basis matrix
Figure BDA00014667871000000532
Figure BDA00014667871000000533
Representation matrix T2One column vector (1. ltoreq. k. ltoreq.L-N +1), the invention maximizes
Figure BDA00014667871000000534
To maximize reception and thereby design precoding vectors
Figure BDA00014667871000000535
Namely, it is
Figure BDA00014667871000000536
(3) Symbol separation and beamforming.
Figure BDA00014667871000000537
Mapping the bit stream into a complex signal of unit power by using M-ary modulation technology (MPSK or QAM modulation)
Figure BDA00014667871000000538
Wherein
Figure BDA00014667871000000539
And
Figure BDA00014667871000000540
are respectively complex signals
Figure BDA00014667871000000541
Real and imaginary parts of (c). Then, constructed using symbol separation techniques and beamforming techniques
Figure BDA00014667871000000542
Is sent out
Figure BDA00014667871000000543
Wherein,
Figure BDA00014667871000000544
(Psto represent
Figure BDA00014667871000000545
The transmission power of),
Figure BDA00014667871000000546
and
Figure BDA00014667871000000547
is the precoding vector designed by the present invention.
In accordance with the above symbol separation, beamforming and precoding design, at the selection
Figure BDA00014667871000000548
And
Figure BDA00014667871000000549
the positions respectively receive the real part and the imaginary part of the useful signal and superpose the additive complex Gaussian noise, other unselected relays can only receive the additive complex Gaussian noise, namely the signal received by the relay node can be expressed as
Figure BDA0001466787100000061
Wherein,
Figure BDA00014667871000000644
is shown in
Figure BDA0001466787100000062
The received additive complex Gaussian noise has a mean value of 0 and a variance of N0，i＝1，…，N。
And step two, in a second time slot of the information transmission process, respectively finishing the operations of relay amplification forwarding, source node cooperative interference and combined receiving.
(1) And (5) relay amplification forwarding. Selected relay
Figure BDA0001466787100000063
And
Figure BDA0001466787100000064
amplifying the forwarded signal to
Figure BDA0001466787100000065
And
Figure BDA0001466787100000066
wherein, mumAnd munTo represent
Figure BDA0001466787100000067
And
Figure BDA0001466787100000068
the amplification factor of, the power constraint needs to be satisfied
Figure BDA0001466787100000069
And
Figure BDA00014667871000000610
Figure BDA00014667871000000611
and
Figure BDA00014667871000000612
is composed of
Figure BDA00014667871000000613
And
Figure BDA00014667871000000614
the transmit power of. In fact, it is possible to use,
Figure BDA00014667871000000615
and
Figure BDA00014667871000000616
the real and imaginary parts of the useful signal contaminated by the repeating noise are amplified separately. At this time, all other unselected relays can hear the signal
Figure BDA00014667871000000617
And
Figure BDA00014667871000000618
(2) and source node cooperative interference. To prevent eavesdropping of useful signals by other unselected relays [5 ]]By the source node
Figure BDA00014667871000000619
And sending the artificial noise to all the relay nodes.It should be noted that, due to long distance transmission or shadowing effects,
Figure BDA00014667871000000620
and
Figure BDA00014667871000000621
there is no direct-transfer link between them,
Figure BDA00014667871000000622
the artificial noise cannot be received, so the artificial noise does not interfere
Figure BDA00014667871000000623
Normal reception.
(3) And combining and receiving. In that
Figure BDA00014667871000000624
Where the received signal is
Figure BDA00014667871000000625
Wherein,
Figure BDA00014667871000000626
is that
Figure BDA00014667871000000627
The total equivalent noise. By means of the method of regular inversion,
Figure BDA00014667871000000628
to decode useful information
Figure BDA00014667871000000629
Is estimated value of
Figure BDA00014667871000000630
(wherein,
Figure BDA00014667871000000631
and
Figure BDA00014667871000000632
respectively represent
Figure BDA00014667871000000633
And
Figure BDA00014667871000000634
estimated value of) can be expressed as
Figure BDA00014667871000000635
Wherein,
Figure BDA00014667871000000636
is that
Figure BDA00014667871000000637
And
Figure BDA00014667871000000638
the equivalent channel matrix in between is used,
Figure BDA00014667871000000639
the specific implementation mode of the invention comprises the following steps:
first time slot
In the first time slot of information transmission, operations such as relay selection, precoding design, symbol separation and beam forming, relay reception and the like are respectively completed, and the detailed process is described as follows:
defining a channel matrix
Figure BDA00014667871000000640
Represents from
Figure BDA00014667871000000641
Channel vectors to the ith relay (1 ≦ i ≦ N).
(1) And (4) relay selection. According to channel vector
Figure BDA00014667871000000642
Calculating channel gain
Figure BDA00014667871000000643
(||·||2Representing the 2 norm of the vector). Selecting the two relays with the strongest channel gains, i.e.
Figure BDA0001466787100000071
Maximum two relays
Figure BDA0001466787100000072
And
Figure BDA0001466787100000073
wherein i is more than or equal to 1, m, N is more than or equal to N, and m is not equal to N.
(2) Precoding vectors
Figure BDA0001466787100000074
And
Figure BDA0001466787100000075
and (5) designing. For the
Figure BDA0001466787100000076
Is designed to be
Figure BDA0001466787100000077
Is sent to
Figure BDA0001466787100000078
Ensuring that other relays do not receive
Figure BDA0001466787100000079
Thereby ensuring that
Figure BDA00014667871000000710
Security of the transmission. In the same way, for
Figure BDA00014667871000000711
Is designed to be
Figure BDA00014667871000000712
Is sent to
Figure BDA00014667871000000713
Ensuring that other relays do not receive
Figure BDA00014667871000000714
Thereby ensuring that
Figure BDA00014667871000000715
Security of the transmission. Based on the fact that the precoding vector is constructed by using a null space method
Figure BDA00014667871000000716
And
Figure BDA00014667871000000717
define from
Figure BDA00014667871000000718
To
Figure BDA00014667871000000719
To and from
Figure BDA00014667871000000720
To
Figure BDA00014667871000000721
Channel matrix for all relays except
Figure BDA00014667871000000722
And
Figure BDA00014667871000000723
is composed of
Figure BDA00014667871000000724
For those in formula (1)
Figure BDA00014667871000000725
Singular value decomposition is carried out to obtain
Figure BDA00014667871000000726
Wherein,
Figure BDA00014667871000000727
is composed of
Figure BDA00014667871000000728
The diagonal matrix of all singular values can be further divided into
Figure BDA00014667871000000729
And
Figure BDA00014667871000000730
is a unitary matrix. The decomposition matrix V may be given as V ═ V1V2]Wherein
Figure BDA00014667871000000731
And V is2The column of (a) is a subspace of (b)
Figure BDA00014667871000000732
Of zero space, i.e.
Figure BDA00014667871000000733
In the same way, can obtain
Figure BDA00014667871000000734
A set of orthogonal basis matrices corresponding to the null space of
Figure BDA00014667871000000735
Suppose that
Figure BDA00014667871000000736
Representation matrix V2A column vector (j is more than or equal to 1 and less than or equal to L-N +1),
Figure BDA00014667871000000737
representation matrix T2One column vector (1. ltoreq. k. ltoreq.L-N +1), the invention maximizes
Figure BDA00014667871000000738
And
Figure BDA00014667871000000739
to maximize reception and thereby design precoding vectors
Figure BDA00014667871000000740
And
Figure BDA00014667871000000741
is composed of
Figure BDA00014667871000000742
(3) Symbol separation and beamforming.
Figure BDA00014667871000000743
Mapping useful information bit stream information into complex signal with unit power by using M-ary modulation technology (MPSK or QAM modulation)
Figure BDA00014667871000000744
Wherein
Figure BDA00014667871000000745
And
Figure BDA00014667871000000746
are respectively complex signals
Figure BDA00014667871000000747
Real and imaginary parts of (c). Then, constructed using symbol separation techniques and beamforming techniques
Figure BDA00014667871000000748
Is transmitted as a signal xsAnd will be useful signals
Figure BDA00014667871000000749
Respectively, the real and imaginary signals of the selected relay
Figure BDA00014667871000000750
And
Figure BDA00014667871000000751
assuming that the real and imaginary parts are transmitted with equal power,
Figure BDA00014667871000000752
is transmitted as a signal xsCan be expressed as
Figure BDA00014667871000000753
Wherein,
Figure BDA00014667871000000754
(Psto represent
Figure BDA00014667871000000755
The transmission power of),
Figure BDA00014667871000000756
and
Figure BDA00014667871000000757
representing the designed precoding vector.
(4) And (4) relay receiving. Signals received by the ith relay node
Figure BDA00014667871000000758
Is composed of
Figure BDA0001466787100000081
Wherein,
Figure BDA0001466787100000082
is shown in the relay
Figure BDA0001466787100000083
The mean value of the additive complex Gaussian noise is 0 and the variance is N0，i＝1，…，N。
The signals received at the N-th relay node are 1, … according to the previous symbol separation, beamforming and precoding design
Figure BDA0001466787100000084
Is composed of
Figure BDA0001466787100000085
Due to precoding vectors
Figure BDA0001466787100000086
And
Figure BDA0001466787100000087
when i is not equal to m,
Figure BDA0001466787100000088
when i ≠ n, the signal is,
Figure BDA0001466787100000089
the signal received by the relay can be expressed as:
Figure BDA00014667871000000810
the real part and the imaginary part of the useful signal are directionally transmitted respectively by using the symbol separation and the beam forming technology. It can be seen from the simulated figure 2 that the relay is in the middle of the simulation
Figure BDA00014667871000000811
In the relay, the received signal lacks a real part
Figure BDA00014667871000000812
Lack of imaginary part in the received signal, in the case of communication systems using QPSK modulation, in the relay
Figure BDA00014667871000000813
And
Figure BDA00014667871000000814
a relatively large error rate, approximately 0.25dB, is achieved. At other relays, the received signal is only additive white gaussian noise and does not contain any useful information.
Second time slot
In the second time slot of information transmission, the operations of relay amplification forwarding, source node cooperative interference and combined reception are respectively completed, and the detailed process is described as follows:
(1) and (5) relay amplification forwarding. Selected relay
Figure BDA00014667871000000815
And
Figure BDA00014667871000000816
amplifying the forwarded signal to
Figure BDA00014667871000000817
And
Figure BDA00014667871000000818
wherein, mumAnd munTo represent
Figure BDA00014667871000000819
And
Figure BDA00014667871000000820
the amplification factor of, the power constraint needs to be satisfied
Figure BDA00014667871000000821
And
Figure BDA00014667871000000822
Figure BDA00014667871000000823
and
Figure BDA00014667871000000824
is composed of
Figure BDA00014667871000000825
And
Figure BDA00014667871000000826
the transmit power of.
(2) And source node cooperative interference. In fact, it is possible to use,
Figure BDA00014667871000000827
and
Figure BDA00014667871000000828
the real and imaginary parts of the useful signal contaminated by the repeating noise are amplified separately. At this time, all other unselected relays can hear the signal
Figure BDA00014667871000000829
And
Figure BDA00014667871000000830
to prevent eavesdropping of useful signals by other unselected relays [5 ]]By the source node
Figure BDA00014667871000000831
And sending the artificial noise to all the relay nodes. It should be noted that, due to long distance transmission or shadowing effects,
Figure BDA00014667871000000832
and
Figure BDA00014667871000000833
there is no direct-transfer link between them,
Figure BDA00014667871000000834
the artificial noise cannot be received, so the artificial noise does not interfere
Figure BDA00014667871000000835
Normal reception.
(3) And combining and receiving. Suppose that the signal forwarded to the destination node by the ith relay is
Figure BDA00014667871000000836
Then at the destination node
Figure BDA00014667871000000837
To the received signal forwarded by the ith relay
Figure BDA00014667871000000838
Is composed of
Figure BDA00014667871000000839
Wherein,
Figure BDA0001466787100000091
is that
Figure BDA0001466787100000092
At the time of the reception of the additive complex gaussian noise,
Figure BDA0001466787100000093
is the ith relay to
Figure BDA0001466787100000094
The channel vector of (2).
Destination node
Figure BDA0001466787100000095
The received signal is from a relay
Figure BDA0001466787100000096
And
Figure BDA0001466787100000097
is represented by
Figure BDA0001466787100000098
Wherein,
Figure BDA0001466787100000099
is that
Figure BDA00014667871000000910
The total equivalent noise.
By means of the method of regular inversion,
Figure BDA00014667871000000911
to decode useful information
Figure BDA00014667871000000912
Is estimated value of
Figure BDA00014667871000000913
(wherein,
Figure BDA00014667871000000914
and
Figure BDA00014667871000000915
respectively represent
Figure BDA00014667871000000916
And
Figure BDA00014667871000000917
estimated value of) can be expressed as
Figure BDA00014667871000000918
Wherein,
Figure BDA00014667871000000919
is a relay
Figure BDA00014667871000000920
And
Figure BDA00014667871000000921
the equivalent channel matrix in between is used,
Figure BDA00014667871000000922
the invention simulates the error rate performance of the proposed relay selection scheme. In the scheme, QPSK modulation technology is adopted, and a source node
Figure BDA00014667871000000923
And destination node
Figure BDA00014667871000000924
The number of antennas of (1) is L-8 and Z-2, respectively. Assuming a repeating network with 4 independent channels, the output power is set to
Figure BDA00014667871000000925
(i ═ 1,2, 3, 4); all received noise powers are assumed to be N0By changing from 1 to 1
Figure BDA00014667871000000926
Transmission power P ofsTo adjust the signal-to-noise ratio (SNR). All simulations were run 10000 times independently using a fading channel model. To show the performance advantages of the proposed symbol separation and beamforming with channel selection scheme of the present invention, we introduce two other commonly used security transmission schemes for comparison. The first is an artificial noise scheme (document [5 ]]Denoted as "AN scheme"), source node
Figure BDA00014667871000000927
Sending signal to relay node with strongest channel gain, carrying out equivalent power distribution in artificial noise and useful signal to obtain higher safety (when the proportion of power distribution is slightly changed, its safety is not affected), supposing that the signal is distributed to transmission signal
Figure BDA00014667871000000928
Has a power of 0.55PsThe power allocated to the artificial noise is 0.45Ps. The second scheme is a destination node cooperative interference scheme (document [ 6]]Denoted as "DJ protocol"),
Figure BDA00014667871000000929
the power of the transmitted interference signal is 0.5Ps. It should be noted that the above AN scheme, DJ scheme and the proposed scheme of the present invention, in the second time slot,
Figure BDA00014667871000000930
a cooperative jamming signal must be transmitted to prevent the useful signal forwarded by the selected relay from being eavesdropped by other relays.
Figure 2 compares the BER performance at the relay and at the destination node for the proposed scheme of the present invention with the AN scheme, the DJ scheme. In the AN and DJ schemes, there is a high error rate at the untrusted relay, however, due to the waste of part of the transmission power in transmitting artificial noise or cooperative interference, the error rate performance at the destination node is poor, 0.125 and 0.07 respectively; the scheme provided by the invention has good safety, the error rate is larger at the selected relay, and due to the orthogonal transmission of the beam forming technology, the transmission power P is carried outsThe error rate performance at the destination node is obviously improved. Therefore, the scheme provided by the invention has obvious improvement on the safety of the untrusted relay and the reliability of the destination node.
And (4) conclusion: aiming at the application scenario of safe transmission of multiple antennas and multiple untrusted relays, the invention provides a new scheme combining symbol separation and beam forming technologies, and the safe transmission of information in an untrusted multiple relay network is ensured. Compared with the existing AN or DJ scheme, the scheme provided by the invention realizes higher BER performance of the relay node and lower BER performance of the destination node, and can obtain reliable system safe transmission.

Claims (1)

1. A safe transmission method of an untrusted relay network based on symbol separation and beam forming is characterized by comprising the following steps:
step one, in a first time slot of an information transmission process, completing relay selection, precoding design, symbol separation and beam forming, specifically comprising the following contents:
(1) for a source node
Figure FDA0002629643250000011
N untrusted relay nodes
Figure FDA0002629643250000012
And a destination node
Figure FDA0002629643250000013
Formed multi-antenna, multi-untrusted relay network, assuming
Figure FDA0002629643250000014
Is provided with L antennas, and the L antennas are arranged,
Figure FDA0002629643250000015
z antennas are arranged, all relays are single antennas, L is more than or equal to N and more than or equal to 2,
Figure FDA0002629643250000016
and
Figure FDA0002629643250000017
there is no direct transmission link between them, all nodes work in half-duplex mode, and all the nodes receive noise with mean value 0 and variance N0Additive complex gaussian noise of (1); channel vector according to ith relay
Figure FDA0002629643250000018
Two relays with the strongest channel gain are selected
Figure FDA0002629643250000019
And
Figure FDA00026296432500000110
wherein 1 is less than or equal to i, m and nN is less than or equal to N, and m is not equal to N;
(2) definition except for
Figure FDA00026296432500000111
To
Figure FDA00026296432500000112
And from
Figure FDA00026296432500000113
To
Figure FDA00026296432500000114
The channel matrixes of all other relays are respectively
Figure FDA00026296432500000115
And
Figure FDA00026296432500000116
wherein the subscript
Figure FDA00026296432500000117
And
Figure FDA00026296432500000118
respectively representing a set {1, 1., m-1, m +1, …, N } except m and N, and a set {1, 1., N +1, …, N } obtained by singular value decomposition
Figure FDA00026296432500000119
Wherein,
Figure FDA00026296432500000120
is composed of
Figure FDA00026296432500000121
A diagonal matrix of all the singular values,
Figure FDA00026296432500000122
and
Figure FDA00026296432500000123
is a unitary matrix; decomposing matrix V to obtain V ═ V1V2]Wherein
Figure FDA00026296432500000124
And V is2The column of (a) is a subspace of (b)
Figure FDA00026296432500000125
A null space of (a); suppose that
Figure FDA00026296432500000126
Representation matrix V21 ≦ j ≦ L-N +1 by maximizing
Figure FDA00026296432500000127
Designing precoding vectors
Figure FDA00026296432500000128
In the same way, obtain and
Figure FDA00026296432500000129
of the orthogonal basis matrix
Figure FDA00026296432500000130
Figure FDA00026296432500000131
Representation matrix T2K is more than or equal to 1 and less than or equal to L-N +1, and designing precoding vectors
Figure FDA00026296432500000132
Suppose that
Figure FDA00026296432500000133
Representation matrix T21 ≦ k ≦ L-N +1 by maximizing
Figure FDA00026296432500000134
Designing precoding vectors
Figure FDA00026296432500000135
Is composed of
Figure FDA00026296432500000136
(3)
Figure FDA00026296432500000137
Mapping a bit stream into a complex signal of one unit power by using M-ary modulation technique
Figure FDA00026296432500000144
Wherein
Figure FDA00026296432500000145
And
Figure FDA00026296432500000146
are respectively complex signals
Figure FDA00026296432500000147
Real and imaginary parts of, constructed using symbol separation techniques and beamforming techniques
Figure FDA00026296432500000143
Is sent out
Figure FDA00026296432500000138
Wherein,
Figure FDA00026296432500000139
Psto represent
Figure FDA00026296432500000140
The transmission power of (a); at the selection of
Figure FDA00026296432500000141
And
Figure FDA00026296432500000142
the positions respectively receive the real part and the imaginary part of a useful signal and superpose additive complex Gaussian noise, other unselected relays can only receive the additive complex Gaussian noise, and the signals received by the relay nodes are expressed as
Figure FDA0002629643250000021
Wherein,
Figure FDA0002629643250000022
is shown in
Figure FDA0002629643250000023
Processing the received additive complex gaussian noise;
step two, in a second time slot of the information transmission process, completing relay amplification forwarding, source node cooperative interference and combined reception, wherein the specific contents are as follows:
(1) selected relay
Figure FDA0002629643250000024
And
Figure FDA0002629643250000025
amplifying the forwarded signal to
Figure FDA0002629643250000026
And
Figure FDA0002629643250000027
wherein, mumAnd munTo represent
Figure FDA0002629643250000028
And
Figure FDA0002629643250000029
the amplification factor of (a) is,
Figure FDA00026296432500000210
and
Figure FDA00026296432500000211
Figure FDA00026296432500000212
and
Figure FDA00026296432500000213
is composed of
Figure FDA00026296432500000214
And
Figure FDA00026296432500000215
the transmit power of (a);
(2) by the source node
Figure FDA00026296432500000216
Sending artificial noise to all relay nodes;
(3) in that
Figure FDA00026296432500000217
To the received signal
Figure FDA00026296432500000218
Wherein,
Figure FDA00026296432500000241
representing a destination node
Figure FDA00026296432500000219
Receive from m and n relay nodes
Figure FDA00026296432500000220
And
Figure FDA00026296432500000221
) The signal of (a) is received,
Figure FDA00026296432500000222
and
Figure FDA00026296432500000223
denotes the m-th and n-th relay nodes (
Figure FDA00026296432500000224
And
Figure FDA00026296432500000225
) To the destination node
Figure FDA00026296432500000226
Of the channel vector ndRepresenting a destination node
Figure FDA00026296432500000227
The received noise vector is then used to determine the noise vector,
Figure FDA00026296432500000228
is that
Figure FDA00026296432500000229
Total equivalent noise; by means of the method of regular inversion,
Figure FDA00026296432500000230
to decode useful information
Figure FDA00026296432500000238
Is estimated value of
Figure FDA00026296432500000231
Wherein,
Figure FDA00026296432500000232
and
Figure FDA00026296432500000233
respectively represent
Figure FDA00026296432500000239
And
Figure FDA00026296432500000240
is determined by the estimated value of (c),
Figure FDA00026296432500000234
is that
Figure FDA00026296432500000235
And
Figure FDA00026296432500000236
the equivalent channel matrix in between is used,
Figure FDA00026296432500000237
CN201711118285.9A 2017-11-14 2017-11-14 Safe transmission method of untrusted relay network based on symbol separation and beam forming Active CN107994934B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201711118285.9A CN107994934B (en) 2017-11-14 2017-11-14 Safe transmission method of untrusted relay network based on symbol separation and beam forming

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201711118285.9A CN107994934B (en) 2017-11-14 2017-11-14 Safe transmission method of untrusted relay network based on symbol separation and beam forming

Publications (2)

Publication Number Publication Date
CN107994934A CN107994934A (en) 2018-05-04
CN107994934B true CN107994934B (en) 2020-10-27

Family

ID=62030300

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201711118285.9A Active CN107994934B (en) 2017-11-14 2017-11-14 Safe transmission method of untrusted relay network based on symbol separation and beam forming

Country Status (1)

Country Link
CN (1) CN107994934B (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109586772B (en) * 2019-01-08 2021-02-09 五邑大学 Multi-antenna wireless relay MIMO system and transmission method thereof
CN115102591B (en) * 2022-08-25 2023-01-20 北京智芯微电子科技有限公司 Beam forming method, device and equipment based on water back injection and readable storage medium

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104378757A (en) * 2014-12-10 2015-02-25 山东大学 Method for guaranteeing physical layer security in multi-relay multi-interference wiretapping network
CN105515717A (en) * 2015-11-30 2016-04-20 华侨大学 Cooperative relay security transmission method based on artificial noise interference
CN106374980A (en) * 2016-07-27 2017-02-01 西安交通大学 Safe transmission method in MIMO Y eavesdropping network based on real interference alignment
CN106788643A (en) * 2016-12-29 2017-05-31 中国人民解放军理工大学 A kind of safe method for precoding of multi-user to end-to-end relay system
EP3202052A1 (en) * 2014-09-29 2017-08-09 Telefonaktiebolaget LM Ericsson (publ) Interference and/or power reduction for multiple relay nodes using cooperative beamforming

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3202052A1 (en) * 2014-09-29 2017-08-09 Telefonaktiebolaget LM Ericsson (publ) Interference and/or power reduction for multiple relay nodes using cooperative beamforming
CN104378757A (en) * 2014-12-10 2015-02-25 山东大学 Method for guaranteeing physical layer security in multi-relay multi-interference wiretapping network
CN105515717A (en) * 2015-11-30 2016-04-20 华侨大学 Cooperative relay security transmission method based on artificial noise interference
CN106374980A (en) * 2016-07-27 2017-02-01 西安交通大学 Safe transmission method in MIMO Y eavesdropping network based on real interference alignment
CN106788643A (en) * 2016-12-29 2017-05-31 中国人民解放军理工大学 A kind of safe method for precoding of multi-user to end-to-end relay system

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Lun Dong;Zhu Han;Athina P. Petropulu;H. Vincent Poor.Improving Wireless Physical Layer Security via Cooperating Relays.《IEEE Transactions on Signal Processing》.2009, *

Also Published As

Publication number Publication date
CN107994934A (en) 2018-05-04

Similar Documents

Publication Publication Date Title
CN109743729B (en) Secret transmission method of wireless energy-carrying cooperative system
Ntranos et al. Cellular interference alignment
Serafimovski et al. Dual-hop spatial modulation (Dh-SM)
CN106059705B (en) A kind of relaying safe transmission method of physical layer
CN107124245B (en) Full duplex one-way junction self-interference suppressing method based on combined transceiving beam forming
Liu et al. Artificial-noise-aided transmission in multi-antenna relay wiretap channels with spatially random eavesdroppers
US20040192395A1 (en) Co-channel wireless communication methods and systems using nonsymmetrical alphabets
Gong et al. Intelligent reflecting surface aided secure communications for NOMA networks
Rui et al. On the performance of full-duplex relaying with relay selection
CN105636215B (en) The interference neutralization method dynamically distributed based on power
Karavolos et al. HST-NNC: A novel hybrid satellite-terrestrial communication with NOMA and network coding systems
Khan et al. Modulation based non-orthogonal multiple access for 5G resilient networks
Wang et al. Multicast secrecy rate maximization for reconfigurable intelligent surface backscatter communication
CN107994934B (en) Safe transmission method of untrusted relay network based on symbol separation and beam forming
Nguyen et al. Short packet communications for cooperative UAV-NOMA-based IoT systems with SIC imperfections
Afana et al. Distributed beamforming for two-way DF relay cognitive networks under primary–secondary mutual interference
CN108631825B (en) Physical layer safety transmission method for enhancing bidirectional AF relay cooperation wireless communication system
Wei et al. Design of generalized analog network coding for a multiple-access relay channel
CN106230476A (en) Information secure transmission method based on non-associating man made noise in insincere relay system
Maham et al. Interference analysis and management for spatially reused cooperative multihop wireless networks
Ibrahim et al. Multiway distributed wireless relay network with projected binary quantization
Tian et al. Relay-aided interference alignment for the X channel with limited CSI
CN107425887B (en) Beam forming method in multi-antenna untrusted relay network
Huang et al. Joint decode-and-forward and cooperative jamming for secure wireless communications
Li et al. Joint source-and-relay beamforming for multiple-input multiple-output systems with single-antenna distributed relays

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant