CN111585621B - Communication method based on antenna selection of maximized artificial noise power - Google Patents

Abstract

The invention provides a communication method for antenna selection based on maximized artificial noise power, which comprises the following steps: 1) both communication parties determine the total number of transmitting antennas and the total number of receiving antennas, and each time slot uses a plurality of transmitting antennas and 1 receiving antenna during appointed communication; 2) calculating artificial noise power, and selecting a plurality of transmitting antennas which maximize the artificial noise power and 1 receiving antenna as a communication transmitting and receiving antenna; 3) the sender uses the random weighting coefficient to weight the modulation symbol and then sends out the modulation symbol through a certain active antenna determined by spatial modulation, and the receiver receives the modulation symbol through the active receiving antenna and mediates and recovers the information bit. The invention further deteriorates the bit error rate performance of the eavesdropper by maximizing the power of the artificial noise, and simultaneously further enhances the bit error rate performance of a legal receiver because the artificial noise is related to the modulus of the channel information.

Description

Communication method based on antenna selection for maximizing artificial noise power

technical field

The invention belongs to the technical field of wireless communication physical layer security, and relates to multiple input multiple output (Multiple Input Multiple Output, MIMO) technology, spatial modulation (Spatial Modulation, SM) technology, artificial noise (Artificial Noise, AN) technology, antenna selection (Antenna Selection) technology , AS) technology.

Background technique

Spatial modulation is proposed as a new multiple-input multiple-output method, which can activate only one antenna in a time slot, and use the activated antenna index to carry other information, while reducing the complexity of the transceiver. Specifically, the spatial modulation system conveys two types of information: (1) the combination of active transmit antennas; (2) the symbols transmitted on the active antennas.

Considering that spatial modulation faces the risk of leaking information to illegal eavesdroppers, physical layer security becomes challenging in spatial modulation. In traditional MISO systems, artificial noise is proposed to enhance safety. By introducing AN into the Spatial Modulation-Multiple Input Single Output (SM-MISO) system, some scholars proposed a secure Unitary Coded Spatial Modulation (UC-SM) scheme. The purpose is to generate time-varying interference to eavesdroppers. Alice, the sender, and Bob, the receiver, transmit the same information in two different time slots, so the legitimate receiver can obtain twice the transmit diversity gain. In the UC-SM system, a transmission group is divided into four time slots, and two different modulation symbols are transmitted respectively. However, UC-SM has the limitation of a single receive antenna, which results in a performance penalty for the receiver. Although antenna selection has been widely used in spatial modulation-multiple input multiple output SM-MIMO systems, it is still challenging to conceive a new antenna selection criterion based on physical layer security in UC-SM systems.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to propose an antenna selection standard based on maximizing artificial noise (Artificial-Noise-Maximization, ANM) power and in the The implementation of joint transmit and receive antenna selection in the UC-SM system can achieve a better balance between security performance and computational complexity.

The technical solution adopted by the present invention to solve the above-mentioned technical problems is, a communication method based on antenna selection for maximizing artificial noise power, comprising the following steps:

1) Both parties in the communication determine the total number of transmitting antennas and the total number of receiving antennas, and the specified spatial modulation range is N _t transmitting antennas and one receiving antenna, and N _t >1;

2) Calculate the artificial noise power, and select N _t transmitting antennas and one receiving antenna that maximize the artificial noise power as the transmitting and receiving antennas for communication;

3) The information bits of the sender are spatially modulated to obtain modulation symbols, and one activation is determined in the N _t transmitting antennas. After the modulation symbols are weighted using random weighting coefficients, the activated antenna determined by spatial modulation will use the weighted modulation The symbol is transmitted, and the receiver receives the modulation symbol through an activated receiving antenna and modulates and recovers the information bits.

Aiming at the problem that the existing antenna selection technology only considers the legitimate party performance and has high complexity, the present invention selects the antenna based on the criterion of maximizing artificial noise power, and applies the criterion in the UC-SM security system. In the UC-SM system, the BER performance of the eavesdropper is further deteriorated by maximizing the power of the artificial noise, and at the same time, since the AN is related to the modulo value of the channel information, the BER performance of the legitimate receiver is further enhanced.

The beneficial effect of the invention is that the eavesdropping ability of the eavesdropper can be suppressed, and the transmission performance between the legitimate two parties is enhanced at the same time. At the same time, it has lower complexity and avoids the disadvantage of high complexity of traditional antenna selection.

Description of drawings

1 is a block diagram of an antenna selection system based on maximizing artificial noise power proposed by the present invention;

Figure 2 shows the performance comparison between the antenna selection scheme using the ANM criterion and the traditional UC-SM system in the UC-SM system when N _T =6, N _t =4, _NR =3, where ANM-AS represents the present invention method, Original represents the bit error rate performance of the traditional UC-SM system;

FIG. 3 shows the performance comparison between the antenna selection scheme using the ANM criterion and the traditional UC-SM system in the UC-SM system when N _T =7, N _t =4, and _NR =3.

Detailed ways

In order to better describe the present invention, the terms and system structures used in the technical solutions of the present invention are first introduced.

MIMO: MIMO technology refers to the use of multiple transmit and receive antennas at the transmitter and receiver, respectively, so that signals are transmitted and received through multiple antennas at the transmitter and receiver, thereby improving communication quality.

SM: SM technology is a new type of multi-antenna transmission technology. It uses the activation state of the antenna as a new means of digital modulation, and turns the index information of the activated antenna into an additional way of carrying data. It is a very promising wireless physics technology. Layer transfer technology.

AN: AN technology refers to the physical layer technology that artificially adds noise that does not affect the demodulation of the legitimate receiver in the transmitted signal vector, so that the eavesdropper is disturbed by the artificially added noise, thereby improving the security.

AS: The basic starting point of the AS technology is to select some good antennas for use among all the antennas, which not only takes advantage of the spatial diversity or multiplexing of the MIMO system, but also reduces its hardware complexity.

Fig. 1 shows the block diagram of the antenna selection system under the secure unitary coding spatial modulation proposed by the present invention.

The system implementation is roughly divided into the following steps:

Step 1: Determine the parameters of the system to be selected, that is, determine the total number of transmitting antennas N _T , the total number of receiving antennas N _R , and the specified spatial modulation range is N _t transmitting antennas and one receiving antenna, N _t >1;

Step 2: Calculate the artificial noise power, and select the transceiver antenna that maximizes the artificial noise power;

Step 3: The transmitter determines to activate the antenna according to the spatial modulation, and uses random weighting coefficients to weight the modulation symbols and transmits them. The receiver receives the modulation symbols through the selected receiving antenna and modulates and recovers the information bits.

A. UC-SM System Model

表示向下取整运算。此外，经由一个传输组传输的信息比特是2log₂M，M是信号星座的大小。因此，UC-SM系统在四个时隙当中传输的总信息数量如下所示Consider an SM-MIMO system. Alice, the sender, has _NT antennas, Bob, the legitimate receiver, has _NR antennas, and Eve, the eavesdropper, has _Ne antennas. Assuming that Bob can obtain accurate channel state information (Channel State Information, CSI) and feed it back to Alice perfectly, the sender selects N _t antennas from NT during the communication process _, and the receiver selects a receive antenna from _NR . In each time slot of a transmission, Alice selects N _t antennas from N _T antennas for spatial modulation. In spatial modulation, one of the N _t antennas is activated. Therefore, the number of information bits transmitted via the index of the active antenna is

Represents a round-down operation. Furthermore, the information bits transmitted via one transmission group are 2log ₂ M, where M is the size of the signal constellation. Therefore, the total amount of information transmitted by the UC-SM system in the four time slots is as follows

When the N _t antennas selected by Alice and the 1 antenna selected by Bob are determined, the position of the active antenna is determined according to the transmission information, and x ₁ and x ₂ are used to represent two different transmission modulation symbols, and w _i represents the ith random weighting coefficients for each time slot. So the signal received by Bob can be expressed as

u_i服从0均值的复高斯白噪声，方差为

Among them, _yi represents the signal received in the _ith slot, hi represents the CSI corresponding to the active antenna in the ith slot, and obeys the distribution

u _i obeys the complex Gaussian white noise with 0 mean, and the variance is

To further ensure that AN does not affect Bob's detection, the random weight coefficients are generated as follows

Here, βx _is the power ratio of the transmitted signal, _βt represents the power ratio of random artificial noise, and d1 and _d2 are both 0 _- mean, unit-variance Gaussian random noise. β _x and β _t satisfy the following power constraints

Combining the reception vectors of the first two slots and the last two slots respectively, Bob's final reception vector can be expressed as

h ₁₂ =h ₁ w ₁ +h ₂ w ₂ =β _x (h ₁ +h ₂ )

h ₃₄ =h ₃ w ₃ +h ₄ w ₄ =β _x (h ₃ +h ₄ )

Therefore, the artificial noise effect at Bob's side can be eliminated. However, due to the channel independence, artificial noise will have an impact on Eve.

B. Maximize Artificial Noise Algorithm

B1. Calculate the power of artificial noise

当Alice选出N_T中的N_t根，Bob选出N_R的一根后，对应的信道可表示为

h^H＝H(x_b,x_a)，其中x_b为Bob选出天线的索引，

为Alice所选出的N_t根天线的索引集合，x_i(i＝1,2,…,N_t)为第i根选择天线的索引。The ANM-AS scheme proposed by the present invention further deteriorates the bit error rate performance of the eavesdropper by maximizing the power of artificial noise, and the full channel information can be expressed as

When Alice selects the N _t root in NT and Bob selects the _NR root _, the corresponding channel can be expressed as

h ^H =H(x _b ,x _a ), where x _b is the index of Bob's selected antenna,

is the index set of N _t antennas selected by Alice, and x _i (i=1, 2, . . . , N _t ) is the index of the ith antenna selected.

For a selected CSIh ^H and a given random noise d ₁ , d ₂ , the total power of artificial noise in 4 slots can be described as

Among them, ||·|| represents the norm operation,

B2. Calculate the maximum value of artificial noise

Therefore, for a given channel state information and random noise, the ANM-AS scheme can be described as

代表Alice可选激活天线位置的所有集合，共有

种可能的组合。通过遍历所有

种选择情况，将每种情况下的人工噪声功率对应放入矩阵

中，寻找使得人工噪声功率最大化的天线选择方案。通过最大化人工噪声的功率，ANM准则可以进一步恶化窃听方的误码率性能。另外，人工噪声的功率比率越大意味着选择的信道状态信息h_i越大，因此合法接收方会有一个更好的性能。因此，本发明所提出的方案实现了可靠性与安全性之间的权衡，仿真步骤总结如表1。where p=[1,2,...,N _R ] ^T represents all sets of Bob's optional active antenna positions,

Represents all sets of Alice's optional active antenna positions, totaling

possible combinations. by traversing all

There are various selection cases, and the artificial noise power corresponding to each case is put into the matrix

, to find an antenna selection scheme that maximizes the artificial noise power. By maximizing the power of artificial noise, the ANM criterion can further deteriorate the bit error rate performance of the eavesdropper. In addition, the larger the power ratio of artificial noise means the larger the selected channel state information _hi , so the legitimate receiver will have a better performance. Therefore, the solution proposed by the present invention realizes the trade-off between reliability and security, and the simulation steps are summarized in Table 1.

Table 1: ANM-AS Algorithm

个可能的选择，表2给出了浮点运算下的ANM-AS算法的复杂度。Further, the ANM criterion considers the computational complexity in terms of the number of floating point operations (FLOPs). When Alice and Bob's selected antennas are determined, the artificial noise power is calculated to require 39FLOPs. Considering that there are a total of

A possible choice, Table 2 gives the complexity of the ANM-AS algorithm under floating-point operations.

Table 2: Computational Complexity

Simulation results

In the simulation, it is assumed that N _T =6, N _R =3, N _t =4, N _r =1, _Ne =1, and β _t =0.3. The modulation scheme adopts Binary Phase Shift Keying (BPSK) and Quadrature Phase Shift Keying (QPSK). In Rayleigh fading channel, maximum likelihood detection is considered.

Figure 2 (a) and Figure 3 (a) show the BER performance comparison between the traditional UC-SM system using BPSK modulation and the ANM-AS scheme proposed by the present invention under different numbers of antennas.

Figure 2 (b) and Figure 3 (b) compare the BER performance between the UC-SM system using QPSK modulation and the ANM-AS scheme proposed by the present invention under the condition of different numbers of antennas.

As can be seen from Figure 2 and Figure 3, our proposed ANM-AS criterion not only improves the BER and improves the security of the eavesdropping side, but also further reduces the BER and improves the transmission performance on the legitimate receiver side. .

Claims (3)

1. A communication method based on antenna selection that maximizes artificial noise power, comprising the steps of:

1) both communication parties determine the total number of transmitting antennas and the total number of receiving antennas, and the designated space modulation range is N_tRoot transmitting antenna and 1 receiving antenna, N_t＞1；

2) Calculating the artificial noise power, selecting N that maximizes the artificial noise power_tThe root transmitting antenna and the 1 receiving antenna are used as the communication receiving and transmitting antenna;

3) the information bit of the sending party is subjected to space modulation to obtain a modulation symbol and is positioned in the N_tDetermining 1 activation in the root transmitting antenna, performing weighting processing on the modulation symbols by using a random weighting coefficient, transmitting the weighted modulation symbols through the activation antenna determined by spatial modulation, and receiving the modulation symbols by a receiving party through the activated 1 receiving antenna and mediating and recovering information bits;

in order to ensure the elimination of the artificial noise influence at the receiving side, the transmitting side determines a random weighting coefficient corresponding to each time slot according to the power ratio of the transmission signal and the artificial noise.

2. The method of claim 1, wherein the artificial noise power is calculated by:

wherein x is_bFor the index of the selected receive antenna,

is selected N_tIndex set of root transmit antennas, H (x)_b,x_a) Activating N for sender_tA corresponding channel is activated by a root transmitting antenna and a receiving antenna for communication; a (H (x)_b,x_a) Represents a channel H (x)_b,x_a) The artificial noise power of (2); i | · | | represents a norm operation, i is the ith time slot of 4 time slots of one transmission group, and i ═ 1,2,3, 4; h is_iIndicating the channel state information CSI, d corresponding to the i-th time slot active antenna_mIs a gaussian random noise with a mean value of 0,

to round down, m is 1, 2.

3. The method of claim 1, wherein the transmitter sets a random weight coefficient w corresponding to each time slot i in 4 time slots of a transmission group_iComprises the following steps:

wherein, beta_xFor transmitting the power ratio of the signals, beta_tRepresents followingPower ratio of mechanical and artificial noise, d₁And d₂Gaussian random noise, h, all 0 means_iRepresenting the channel state information CSI corresponding to the ith time slot activated antenna; beta is a_xAnd beta_tSatisfies the following conditions:

and activating the variance of the distribution obeyed by the CSI corresponding to the antenna for the ith time slot.

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