阅读说明：本技术 基于noma的d2d通信物理层安全功率分配方法 (NOMA-based D2D communication physical layer safe power distribution method ) 是由 刘琚 徐田凤 于山山 高智超 邬磊 于 2021-09-10 设计创作，主要内容包括：本发明公开了一种基于NOMA的D2D通信物理层安全功率分配方法,属于无线通信技术领域,解决D2D通信在被动窃听下的物理层安全问题,在保证每个D2D用户服务质量的情况下,构建以最大化D2D通信保密率为目标的优化问题。通过优化D2D组发射机DT对DR1及DR2的功率分配,来最大化D2D通信系统的保密率。根据KKT条件,推导出两种情况下的最优功率分配的闭式解,进而通过对比两种情况下的D2D通信系统的保密总速率,得到最终的最优功率分配方法。通过与基于OMA的D2D通信网络的保密率及能量效率对比,所提出的功率分配方法具有更高的保密速率和能量效率。(The invention discloses a NOMA-based D2D communication physical layer security power distribution method, belongs to the technical field of wireless communication, solves the physical layer security problem of D2D communication under passive eavesdropping, and constructs an optimization problem aiming at maximizing the D2D communication secrecy rate under the condition of ensuring the service quality of each D2D user. The secret rate of the D2D communication system is maximized by optimizing the power allocation of the D2D group transmitters DT to DR1 and DR 2. And deducing closed solutions of the optimal power distribution under two conditions according to the KKT condition, and comparing the total secret rates of the D2D communication systems under the two conditions to obtain the final optimal power distribution method. The proposed power allocation method has a higher privacy rate and energy efficiency by contrast to those of OMA based D2D communication networks.)

1.A NOMA-based D2D communication physical layer safe power allocation method is suitable for NOMA-enabled D2D communication system, which comprises a base station BS and a cellular user c₁An eavesdropper Eve and a D2D user group, wherein the D2D user group comprises 1D 2D sending terminal DT and 2D 2D receiving terminals DR₁、DR₂(ii) a Wherein, DR₁The distance to DT is much smaller than the distance DR2 to DT, DR₁For near-end users, has stronger channel gain, DR₂For far-end users, there is a weaker channel gain; D2D transmitting end DT using NOMA scheme and two D2D receiving ends DR₁、DR₂Communication is carried out, and an eavesdropper Eve tries to eavesdrop D2D transmitter DT transmitting to DR₁And DR₂Base station BS is located in the cell centre and uses OMA technology for cellular users c₁Serving, D2D group communication multiplexes spectrum resources of the cellular uplink;

the power allocation method of the communication system specifically comprises the following steps:

the base station acquires ideal channel state information of cellular users c1, D2D receiving terminals DR1, DR2 and eavesdropper Eve and calculates the communication rate of the cellular users, wherein the devices in the system are all single antennas, the channels among the devices are modeled as Rayleigh channels,indicating cellular user c₁To DR₁、DR₂The gain of the interference channel of (a),are DT, c respectively₁The channel gain to the eavesdropper Eve,are DT to DR, respectively₁、DR₂The channel gain of (a);

and the base station calculates the secret rate of the D2D group communication according to the acquired information, calculates the power distribution coefficient at the D2D transmitting end by taking the maximum secret rate of the D2D group as a target, and forwards the power distribution coefficient to the D2D transmitting end.

2. The NOMA-based D2D communication physical layer secure power allocation method according to claim 1, wherein: the secret ratio SR of the D2D group is DR₁、DR₂Communication rate R₁、R₂Sum minus eavesdropper decoding DR₁、DR₂Rate ofWherein the content of the first and second substances, δ²power of additive white Gaussian noise, p_cIs the transmit power of cellular user c 1.

3. The NOMA-based D2D communication physical layer secure power allocation method according to claim 1, wherein: in particular, the eavesdropper Eve decodes DR₁Signal of (2) is DR₂C and c₁The signal of (2) is regarded as an interference signal, and similarly, it is in decoding DR₂When the signal is in (2), DR₁C and c₁The signal of (2) is regarded as an interference signal.

4. The NOMA-based D2D communication physical layer secure power allocation method according to claim 1, wherein: the base station ensures that DR when calculating the power distribution coefficient alpha of the D2D transmitting terminal DT₁、DR₂The minimum communication rate of (a), wherein,is DR₁，DR₂The lowest rate in communication requires a corresponding signal-to-noise ratio.

5. The NOMA-based D2D communication physical layer secure power allocation method according to claim 1, wherein: definition of p₁＝αQ_T，p₂＝(1-α)Q_T，0<α<0.5，p₁For DT end to DR₁Allocated transmission power, p₂For DT end to DR₂Allocated transmission power, Q_TIs the maximum transmission power of the DT end.

6. The NOMA-based D2D communication physical layer secure power allocation method according to claim 1, wherein: base station according to pair DR₁、DR₂The quality of service of (2) is guaranteed, the range of the power distribution coefficient α is calculated:

7. the NOMA-based D2D communication physical layer secure power allocation method according to claim 1, wherein: according to KKT condition, when power distribution coefficientOrWhen the communication security rate of the D2D group is maximum, the base station calculatesToSending to DT, DT compares power distribution coefficientsCorresponding secret ratio Sr₁，Sr₂And selecting the alpha value corresponding to the maximum secret rate as the final power distribution scheme.

Technical Field

The invention relates to the technical field of wireless communication, in particular to a NOMA-based D2D communication physical layer safe power distribution method.

Background

With the rise of intelligent services such as smart homes, smart cities, internet of things, smart power grids and the like, a large number of mobile terminals with limited energy access networks exist in future networks. In this context, efficient utilization of spectrum resources, efficient and repeated use of energy, is of increasing interest to the industry and academia. The number of Access users of a 4G wireless communication network adopting an Orthogonal Multiple Access (OMA) mode is limited by limited Orthogonal resources, and cannot meet the Access of massive users to a certain extent. Different from orthogonal multiple access, Non-orthogonal multiple access (NOMA) in a power domain is one of 5G key technologies, different users are distinguished through the power domain, multiple users are allowed to share the same time-frequency resource, and higher frequency spectrum efficiency and energy efficiency are achieved.

5G another key technology, D2D (Device-to-Device), allows direct communication between two mobile users without going through a base station or core network. D2D communication has the following advantages: 1) neighbor gain, which reduces transmission range by bypassing the base station to achieve extremely high bit rate, low delay, and low power consumption; 2) multiplexing gain, the D2D terminal and the traditional cellular user share the same spectrum resource, thereby improving the spectrum efficiency; 3) single hop gain, single hop in D2D mode, rather than two hops in the traditional cellular mode.

Studies have shown that NOMA technology, in combination with D2D communication, can further improve spectral and energy efficiency. In terms of security, D2D communication is typically by way of interference with cellular links to combat eavesdroppers in the network, but the security of the D2D link itself is difficult to guarantee. Applying NOMA to D2D communication, in turn, introduces co-channel interference, making interference management more complex and handling of security in the presence of an eavesdropper more complex. Therefore, it is very important to research an effective resource allocation strategy to improve the physical layer security of the network.

Disclosure of Invention

Aiming at the physical layer security problem of a communication network enabled by NOMA technology and D2D technology under passive eavesdropping, a NOMA-based D2D communication physical layer security power allocation method is provided. The method establishes the problem of maximizing the secret rate of the D2D communication system under the condition of ensuring the service quality of each D2D user. And deducing closed solutions of optimal power distribution under two conditions according to a (Karush-Kuhn-Tucker) KKT condition, and comparing the secret rates of the D2D communication systems under the two conditions to obtain a final power distribution method. The considered NOMA-based D2D communication network has a higher privacy rate and energy efficiency under the proposed power distribution method compared to the OMA-based D2D communication network.

In order to achieve the purpose, the invention adopts the following technical scheme:

a NOMA-based D2D communication physical layer safe power allocation method is suitable for NOMA-enabled D2D communication system, which comprises a base station BS and a cellular user c₁An eavesdropper Eve and a D2D user group, wherein the D2D user group comprises 1D 2D sending terminal DT and 2D 2D receiving terminals DR₁、DR₂(ii) a Wherein, DR₁The distance to DT is much smaller than the distance DR2 to DT, DR₁For near-end users, has stronger channel gain, DR₂For far-end users, there is a weaker channel gain; D2D transmitting end DT using NOMA scheme and two D2D receiving ends DR₁、DR₂Communication is carried out, and an eavesdropper Eve tries to eavesdrop D2D transmitter DT transmitting to DR₁And DR₂Base station BS is located in the cell centre and uses OMA technology for cellular users c₁Serving, D2D group communication multiplexes spectrum resources of the cellular uplink;

the power allocation method of the communication system specifically comprises the following steps:

the base station acquires ideal channel state information of cellular users c1, D2D receiving terminals DR1, DR2 and eavesdropper Eve and calculates the communication rate of the cellular users, wherein the devices in the system are all single antennas, the channels among the devices are modeled as Rayleigh channels,indicating cellular user c₁To DR₁、DR₂The gain of the interference channel of (a),are DT, c respectively₁The channel gain to the eavesdropper Eve,are DT to DR, respectively₁、DR₂The channel gain of (a);

and the base station calculates the secret rate of the D2D group communication according to the acquired information, calculates the power distribution coefficient at the D2D transmitting end by taking the maximum secret rate of the D2D group as a target, and forwards the power distribution coefficient to the D2D transmitting end.

In particular, the privacy ratio SR of the D2D group is DR₁、DR₂Communication rate R₁、R₂Sum minus eavesdropper decoding DR₁、DR₂Rate ofWherein the content of the first and second substances, δ²power of additive white Gaussian noise, p_cIs the transmit power of cellular user c 1.

In particular, the eavesdropper Eve decodes DR₁Signal of (2) is DR₂C and c₁The signal of (2) is regarded as an interference signal, and similarly, it is in decoding DR₂When the signal is in (2), DR₁C and c₁The signal of (2) is regarded as an interference signal.

In particular, the base station calculates the power distribution coefficient α of the D2D transmitting terminal DTEnsure that DR₁、DR₂The minimum communication rate of (a), wherein,is DR₁，DR₂The lowest rate in communication requires a corresponding signal-to-noise ratio.

In particular, define p₁＝αQ_T，p₂＝(1-α)Q_T，0<α<0.5，p₁For DT end to DR₁Allocated transmission power, p₂For DT end to DR₂Allocated transmission power, Q_TIs the maximum transmission power of the DT end.

In particular, the base station is based on the pair DR₁、DR₂The quality of service of (2) is guaranteed,the range of the power distribution coefficient α is calculated:

in particular, according to the KKT condition, when the power division factorOrWhen the communication security rate of the D2D group is maximum, the base station calculates the obtained rateSending to DT, DT compares power distribution coefficientsCorresponding secret ratio Sr₁，Sr₂And selecting the alpha value corresponding to the maximum secret rate as the final power distribution scheme.

The invention has the beneficial effects that:

1 the method aims at maximizing the secrecy rate of D2D, solves the closed-form solution of the power distribution coefficient, and has low algorithm complexity compared with other methods for solving the power distribution coefficient through iterative updating.

The combination of the 2NOMA technology and the D2D technology can further improve the spectrum efficiency of the system and the system capacity, but also makes the interference management of the system more complicated, and the information of the legal user is easy to be intercepted in the case of an eavesdropper. The power distribution method provided by the invention can effectively resist eavesdropping and ensure the communication safety of a physical layer.

3 the power allocation method provided by the invention is suitable for the situation that the D2D group and the cellular user multiplex the uplink frequency spectrum, and can be expanded to a multi-carrier system, namely a multi-cellular user and multi-D2D group communication scene.

Drawings

FIG. 1 is a system model diagram;

FIG. 2 is a flow diagram of a NOMA-based D2D communication physical layer safe power allocation strategy;

the NOMA power allocation scheme proposed in fig. 3 is compared to the D2D group privacy ratio of the OMA scheme;

fig. 4 simulates the impact of different circuit power losses PC on the energy efficiency of group D2D communications based on the proposed power distribution method and compares it with the energy efficiency of group D2D communications based on OMA.

Detailed Description

In order to more clearly describe the technical contents of the present invention, the present invention will be further described with reference to the accompanying drawings.

The invention provides a NOMA-based D2D communication physical layer security power distribution method, which considers the physical layer security problem of D2D communication under passive eavesdropping, and constructs an optimization problem aiming at maximizing the D2D group communication secrecy rate under the conditions of ensuring the service quality of each D2D user and limiting the power of cellular users and D2D group transmitting terminals. DR for receiving end by optimizing D2D transmitting end DT₁And DR₂To maximize the privacy rate of the D2D communication system. Deducing a closed solution of optimal power distribution under two conditions according to the KKT condition, and thenAnd comparing the secret rates of the D2D communication system in the two cases to obtain the final power distribution method. In contrast to the privacy rate and energy efficiency of the OMA based D2D communication network, the considered NOMA based D2D communication network has a higher privacy rate and energy efficiency based on the proposed power allocation method.

FIG. 1 is a system model diagram, a single-cell communication scenario, a single carrier downlink NOMA-based D2D communication scenario in which a D2D Transmitter (DT) uses NOMA protocol with two D2D Receivers (DR)₁、DR₂) Communication is performed. Meanwhile, there is an eavesdropper, which is a passive eavesdropper, and Eve tries to eavesdrop D2D transmitter DT transmitting to DR₁And DR₂Of the signal of (1). The base station BS is located in the cell centre and uses OMA technology for cellular users (c)₁) Serving, D2D group communication multiplexes the spectrum resources of the cellular uplink. The D2D group consists of a D2D transmitter DT, a D2D receiving end DR1 and DR 2. Suppose in D2D group communication, DR₁For near-end users, has stronger channel gain, DR₂For the far-end user, there is a weak channel gain.

FIG. 2 is a flow chart of the method, which is mainly divided into the following steps:

(1) the base station calculates the communication rate, DR, of the following terminal according to the acquired information₁、DR₂Communication rate R₁、R₂。R₁＝log2(1+SINR^DR1)、R₂＝log2(1+SINR^DR2). Eavesdropper Eve decoding DR₁，DR₂Rate of

(2) Wherein the content of the first and second substances, indicating cellular user c₁To DR₁、DR₂Of the interference channel, delta²Power of additive white Gaussian noise, p_cIs the transmit power of the cellular user (c 1).Are DT, c respectively₁Channel gain to eavesdropper Eve.

(3) Constructing an optimization function with the goal of maximizing the communication security rate of the D2D group, wherein the security rate SR of the D2D group is DR₁、DR₂Is subtracted from the sum of the communication rates of the eavesdropper decoding DR₁、DR₂The rate of (c). The optimization problem is described as follows:

p₁+p₂≤Q_T (1.c)

0<p₁<p₂ (1.d)

formula 1 is an objective function, and the constraint conditions (1.a) (1.b) ensure DR₁、DR₂The quality of communication of (a), wherein,is DR₁，DR₂The minimum rate of (c) requires a constraint. (1.c) (1.d) the NOMA power allocation principle is satisfied, the far-end user allocates more power and the near-end user allocates less power.

(4) Since the sum of the power allocated to the strong and weak users in the D2D group is the maximum transmission power of the DT terminal, a power allocation factor α is introduced. Definition of p₁＝αQ_T，p₂＝(1-α)Q_T，0<α<0.5。p₁For DT end to DR₁Allocated transmission power, p₂For DT end to DR₂Allocated transmission power, Q_TIs the maximum transmission power of the DT end. The optimization objective function can be expressed as:definition, g (α) — f (α) ≦ 0;

(5) the range of power distribution coefficients can be derived from equations (1.a) and (1. b):

(6) the optimization problem can be converted into the following form:

s.t.(K1-α)≤0

(α-K2)≤0

0≤α≤0.5

(7) constructing a Lagrange multiplier of the optimization function in the step 6:

L(.)＝g(α)+(K₁-α)λ₁+(α-K₂)λ₂equation 4

Wherein λ is₁，λ₂Is a lagrange multiplier;

(8) the KKT condition for solving the inequality constraint optimization problem in step 6 is as follows.

(9) Obtaining two power distribution factors according to formula 5

(10) The optimization objective is to maximize the secret ratio of the D2D group, compare the power distribution coefficientsCorresponding secret ratio Sr₁，Sr₂And selecting the alpha value corresponding to the maximum secret rate as the final power distribution scheme.

Fig. 3 simulates the privacy rate of NOMA-based D2D group communications based on the power allocation method proposed in this patent and compares it with the privacy rate of OMA-based D2D group communications. The OMA scheme adopts the traditional FDMA scheme, i.e. the frequency spectrum is in DR₁And DR₂Are equally distributed among them. It can be seen from the simulation results that the D2D group privacy ratio is higher with the NOMA scheme than with the OMA scheme.

Fig. 4 simulates the effect of different circuit power loss values PC on the energy efficiency of a D2D group communication network based on the proposed power allocation method. The energy efficiency is calculated in equation 6, where P is the transmission power at the DT terminal. From the simulation results, it can be seen that with the increase of the circuit power loss value PC, the energy efficiency of the D2D group communication network is reduced under both OMA and NOMA schemes, and the energy efficiency of the D2D communication network adopting the NOMA scheme is higher than that of the D2D communication network adopting the OMA scheme. Specifically, when P is 4W and PC is 0.3, the energy efficiency of the D2D group communication network using the NOMA scheme is 0.4bpj/Hz, whereas under the same simulation setup, the energy efficiency of the D2D group under the OMA scheme is only 0.3731bpj/Hz, and the considered NOMA-based D2D communication network is superior to the OMA-based D2D communication network in energy saving communication based on the proposed power allocation method.

Although the embodiments of the present invention have been described with reference to the accompanying drawings, the scope of the present invention is not limited thereto, and those skilled in the art can make various modifications and variations without inventive changes based on the technical solution of the present invention.