CN105704721A - D2D-P multiplexing cellular network communication method capable of increasing frequency spectrum utilization rate - Google Patents

Abstract

The invention relates to a D2D-P multiplexing cellular network communication method capable of increasing a frequency spectrum utilization rate. The method comprises the following steps of S1, establishing a cellular network; S2, according to Hk,m, using an interference alignment method to acquire a solution set of an N row and d column precoding matrix Fm of each D2D-Pm; S3, calculating an interference matrix Hk,mFm of the D2D-Pm to CUk and designing an N row and d column cellular user postposition coding matrix Wk orthogonal to the Hk,mFm; S4, using the interference alignment method based on a minimum mean square error to acquire transmitter precoding matrixes Fm and receiver postposition coding matrixes Gm of all the D2D-Pm and carrying out communication; S5, setting a SINR threshold omegath of the D2D-Pm and determining whether the D2D-Pm is connected to the cellular network; S6, using an improved water injection power distribution method to send power to all the D2D-Pm distribution; and S7, according to results of the step S2 to the step S6, carrying out communication. Compared to the prior art, by using the method, interferences of the D2D-Ps on a cellular user are aligned to a cellular user position; a communication priority of the cellular user is guaranteed; mutual interference among the D2D-Ps is controlled and a D2D-P sum rate is increased.

Description

D2D-P multiplexing cellular network communication method for improving frequency spectrum utilization rate

Technical Field

The invention relates to a cellular network communication method, in particular to a D2D-P multiplexing cellular network communication method for improving the frequency spectrum utilization rate.

Background

With the rapid development of wireless communication, how to maximize the utilization of spectrum resources under the condition of limited spectrum resources has been a hot point of research. In a cellular network, a device-to-device user pair (D2D-P) is added to the cellular network to multiplex the spectrum resources thereof, which can improve the spectrum utilization rate, but will bring inevitable interference to cellular users, affecting the performance indexes such as the transmission rate of the cellular users.

Aiming at the problems that the cellular network has low utilization rate of frequency spectrum resources and D2D-P causes interference to the cellular network, the following methods are proposed by DaquanFang et al (DaquanFang, LuLuLuLuLu, Yiyuan-Wu, GeoffreyYeLi, GangFeng, ShaoqianLi. device-to-device communications underwritingCellularnets, IEEETRANSACTIONCOMMUNICATIONS, VOL.61, NO.8, pp.3541-3551, AUGUST 2013): by setting a threshold value in advance, selecting qualified D2D-P, then distributing power to potential cellular users and the qualified D2D-P, finally, selecting proper users from the potential cellular users to match with the qualified D2D-P, and maximizing the throughput gain and the access rate of the system by selecting proper range D2D-P, cellular network coverage, active cellular users and the number of D2D-P. The method is limited in the uplink of the cellular network, only ensures the communication requirements of partial cellular users, and does not specifically eliminate the interference caused by the addition of D2D-P into the cellular network.

LuYang et al (LuYang, WeiZhang, Shijin, "interference alignment device-to-device LANderlingering cellular networks", IEEE TRANSACTIONWIRELIES communications, VOL.14, NO.7, PP.3715-3723, July,2015.) use an interference alignment algorithm to resolve the interference caused by the D2D-P multiplexed spectrum resources by: (1) when the uplink of the base station is not fully occupied by cellular users, aligning the interference of D2D-P to the cellular users into these idle links, thereby protecting the cellular users from interference; (2) when the base station uplink is fully occupied, D2D-P can occupy part of the uplink, and when an interference threshold is set, the occupied link interference is controlled below the threshold, thereby controlling the interference to the cellular user. Although the method eliminates the interference of D2D-P to the communication link of the cellular user, when the cellular users are more, the interference caused by D2D-P can not be completely eliminated, and the performance indexes such as the number of accessed D2D-P, the transmission rate and the like are not considered, and only the interruption probability of the D2D-P accessing the cellular network is considered.

JianmoJiang et al (JianmoJiang, MugenPeng, WenboWang, KechengZhang, "energy efficiency information based on estimating information for Device-to-Device MIMOdownLinked cellular network", IEEEGlobom 2013Workshop-International working home Device-to-Device (D2D) communication With and WithwithoutInastmastructure, PP.585-590,2013.) apply the interference alignment algorithm to eliminate the cellular network downlink interference as follows: firstly, the coding technology is adopted to eliminate the interference caused by the addition of D2D-P into the cellular network. Then, aligning the interference between the cellular users to a specific signal dimension by using an interference alignment algorithm, and ensuring that the cellular users are not interfered; finally, post-coding and linear precoding are optimized to maximize the energy efficiency of D2D-P. The interference brought by the D2D-P joining the cellular network and the interference among cellular users are considered, but the performance indexes of the D2D-P communication indexes such as throughput, bit error rate and the like are not considered.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a D2D-P multiplexing cellular network communication method which has low interference, high D2D-P and high rate and improves the spectrum utilization rate.

The purpose of the invention can be realized by the following technical scheme:

a D2D-P multiplexing cellular network communication method for improving spectrum utilization rate is characterized by comprising the following steps:

s1, establishing a cellular network, wherein the cellular network comprises a cellular base station and K cellular user CUs_kAnd M pairs of device-user pairs D2D-P_mK is 1,2, …, K, M is 1,2, …, M, said D2D-P_mThe cellular user, the transmitter and the receiver are respectively provided with N transmitting antenna numbers and N receiving antenna numbers, and a signal vector Z sent from the transmitter to the receiver_mIs D row, 1 column, D2D-P_mTo CU_kOf the channel matrix H_k,mN rows and N columns;

s2, according to H_k,mObtaining D2D-P by interference alignment_mN rows and d columns precoding matrix F_mThe solution set of (1);

s3, calculating D2D-P_mFor CU_kInterference matrix H of_k,mF_mDesigned to be orthogonal to H_k,mF_mN lines ofD-column cellular user postcode matrix W_k，k＝1,2,…,K；

S4, obtaining all D2D-P by interference alignment method based on minimum mean square error_mTransmitter precoding matrix F_mAnd receiver postcoding matrix G_mAnd performs cellular network communication to acquire each cellular subscriber CU_kSignal to interference plus noise ratio (SINR);

s5, setting D2D-P_mSINR threshold ω_thIf D2D-P_mSINR of less than ω_thThen the D2D-P is added_mAccessing cellular network and setting β_mValue 1, otherwise set β_mA value of 0;

s6, precoding matrix F according to the transmitter_mAnd β_mAll D2D-P are subjected to improved water injection power distribution method_mAllocating transmission power P_m；

And S7, performing cellular network communication according to the matrix calculation result and the power distribution result of the steps S2-S6.

The step S2 specifically includes: all D2D-P_mFor CU_kInterference matrix H of_k,mF_mAlign to the CU_kOn the same signal subspace of the receiving end, the following specific equations are provided:

span(H_k,1F₁)＝...＝span(H_k,mF_m)＝...＝span(H_k,MF_M)

where K is 1,2, …, K, span (a) denotes the subspace spanned by the column vectors of matrix a.

The step S4 specifically includes the following steps:

s41, calculating a transmitter precoding matrix F received by the receiver_mProcessed signal level S_mAnd S_mPost-coding matrix G via receiver_mSignal level obtained after processing

S42, definition of all D2D-P_mSignal level mean square error sum_MSEThe following were used:

${\mathrm{\ϵ}}_{MSE}=\underset{m=1}{\overset{M}{\Σ}}E\left\{\right||\stackrel{\‾}{S_m}-S_m|{|}^2\}=\underset{m=1}{\overset{M}{\Σ}}E\left\{\right||{G_m}^H{S}_m-S_m|{|}^2\}$

the optimization problem is solved using the lagrangian multiplier method as follows:

$\begin{array}{cc}\underset{G_m,F_m}{\min }& {\mathrm{\ϵ}}_{MSE}\\ s.t.& \left|\right|F_m|{|}_F^2=P_m\end{array}$

wherein E {. represents the mathematical expectation, | | | X | | ceiling²The square of the norm of the matrix X is represented,f norm, P, representing matrix X_mIs D2D-P_mThe power of the transmission is set to be,p is the total transmit power of all D2D-ps.

In the step S41, the transmitter pre-codes the matrix F_mProcessed signal level S_mThe following formula is specifically calculated:

$S_m=\sqrt{P_m}{H}_{m,m}{F}_m{Z}_m+\underset{j=1,j\≠m}{\overset{M}{\Σ}}\sqrt{P_j}{H}_{m,j}{F}_j{Z}_j+n_m$

wherein, P_mIs D2D-P_mTransmission power of the transmitter, H_m,mIs D2D-P_mN-row, N-column channel matrix, H, from transmitter to receiver_m,jIs D2D-P_jTransmitter to D2D-P_mN-row, N-column channel matrix, N, of a receiver_mIs D2D-P_mAmbient noise received by the receiver.

The step S42 specifically includes the following steps:

s420, introducing a Lagrange multiplier lambda_mTo obtain the Lagrangian function:

$L(F_m,G_m,{\mathrm{\λ}}_m)={\mathrm{\ϵ}}_{MSE}+{\mathrm{\λ}}_m\left(\right|\left|F_m\right|{|}_F^2-P_m)$

wherein,_MSEsee definition of S42.

S421 for G in Lagrange function respectively_m、F_mTaking the partial derivative and making the partial derivative zero, we get equation (1) (2):

$F_m={(\underset{j=1}{\overset{M}{\Σ}}{H}_{j,m}{G}_j{G}_j^H{H}_{j,m}^H+{\mathrm{\λ}}_{m}I)}^{-1}{H}_{m,m}^H{G_m}^H---\left(1\right)$

$G_m={F_m}^H{H_{m,m}}^H{(\underset{j=1}{\overset{M}{\Σ}}{H}_{m,j}{F}_j{F}_j^H{\left(H_{m,j}\right)}^H+{\mathrm{\σ}}^{2}I)}^{-1}---\left(2\right)$

wherein M is 1,2, …, M, sigma²For ambient noise n_mAnd E { n }_mn_m ^H}＝σ²I, I is an N-order identity matrix;

s422, initializing a precoding matrix F_mObtaining a random matrix of N rows and d columns for the random matrix;

s423, calculating by the formula (2) to obtain a post-coding matrix G_m；

S424, substituting the formula (1) into the power limiting conditionFind lambda_m(λ_mNot less than 0), lambda is added_mSubstitution of formula (1), update F_m；

S425, calculating the sum of mean square errors_MSE；

S426, repeating the steps from the step 423 to the step 425 until_MSEConverge to obtain G_mAnd F_m。

In the S5, D2D-P_mCommunication SINR threshold value omega_thComprises the following steps: the cellular users participating in the communication measure the SINR of the local received signal and send the signal to the cellular base station through a feedback channel, and the cellular base station sets the minimum SINR to be D2D-P communication SINR threshold value omega_th. The local received signals comprise all interference of D2D-P to cellular users and signals sent by the base station to all the cellular users; a cellular subscriber receives signals transmitted by the base station to all cellular subscribers, including desired signals and undesired signals, which are considered interference.

In S6, the improved water injection power distribution method is used for solving the D2D-P_mTransmission power P_mThe calculation method comprises the following steps:

P_m＝β_m(μ/γ_m-1)⁺

wherein mu is the level of water injection and satisfiesγ_mIs D2D-P_mThe channel gain of (a) is determined,p is the total transmit power of all D2D-P, function (x)⁺Max (x,0) denotes taking the larger of the real numbers x and 0.

Compared with the prior art, the invention has the following advantages:

(1) the interference of the D2D-P to the cellular user is aligned to the cellular user, and the interference of the D2D-P to the cellular user is eliminated by adopting a post-coding technology, so that the communication priority of the cellular user is ensured.

(2) And the interference between D2D-P is processed by adopting the interference alignment technology based on the minimum mean square error, and a coding matrix of the minimum D2D-P mean square error is calculated, so that the mutual interference between D2D-P is controlled.

(3) Judging whether the D2D-P is accessed to the cellular network or not through a hard decision function, and utilizing an improved water injection power distribution method to perform network addition on the D2D-P_mAllocating transmission power P_mThe D2D-P sum rate is improved.

Drawings

FIG. 1 is a diagram illustrating coexistence interference between cellular users and device users in a cellular network according to the present invention;

FIG. 2 is an overall flow chart of the present invention;

FIG. 3 is a detailed flow chart of the method of the present invention.

Detailed Description

The invention is described in detail below with reference to the figures and specific embodiments. The present embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation manner and a specific operation process are given, but the scope of the present invention is not limited to the following embodiments.

Examples

Fig. 1 is a schematic diagram of coexistence of device-to-device user pairs and cellular users in a cellular network, where the network includes a cellular base station, and the base station is evolved base stations (evolvednodes) of LTE-a (long term evolution-Advanced) standard, and covers the cellular users and the device-to-device user pairs completely. Within its coverage area, there are randomly distributed K cellular users and M pairs of D2D-P, where D2D-P is divided into transmitter and receiver. The number of the cellular users, the number of the D2D-P transmitting antennas and the number of the receiving antennas are all set to be 2, and 2 cellular users and 2 pairs of D2D-P, D2D-P and cellular users can obtain complete channel state information within the coverage range of the cellular base station.

Fig. 2 is a flowchart of a D2D-P multiplexing cellular network communication method for improving spectrum utilization, comprising the following steps:

s1, establishing a cellular network, wherein the cellular network comprises a cellular base station and K cellular user CUs_kAnd M pairs of device-user pairs D2D-P_mK is 1,2, …, K, M is 1,2, …, M, said D2D-P_mThe system comprises a transmitter and a receiver, wherein the number of transmitting antennas and the number of receiving antennas of a cellular user, the transmitter and the receiver are N, and a signal vector sent to the receiver by the transmitter is Z with d rows and 1 column_m，D2D-P_mTo CU_kThe channel matrix is H with N rows and N columns_k,m；

S2, according to H_k,mObtaining D2D-P by interference alignment_mN rows and d columns precoding matrix F_mThe solution set of (1);

s3, calculating D2D-P_mFor CU_kInterference matrix ofH_k,mF_mDesigned to be orthogonal to H_k,mF_mN rows and d columns of cellular subscriber postcode matrix W_k；

S4, obtaining all D2D-P by interference alignment method based on minimum mean square error_mTransmitter precoding matrix F_mAnd receiver postcoding matrix G_mStarting a cellular network to communicate;

s5, setting D2D-P_mSINR threshold ω_thIf D2D-P_mSINR of less than ω_thThen the D2D-P is added_mAccess cellular network, setup β_mRepresents D2D-P_mWhether to access the cellular network, access β_mValue 1, otherwise β_mA value of 0;

s6, precoding matrix F according to the transmitter_mAnd β_mAll D2D-P are subjected to improved water injection power distribution method_mAllocating transmission power P_m；

And S7, performing cellular network communication according to the matrix calculation result and the power distribution result of the steps S2-S6.

The step S2 specifically includes: all D2D-P_mFor CU_kInterference matrix H of_k,mF_mAlign to the CU_kOn the same signal subspace of the receiving end, the following specific equations are provided:

span(H_k,1F₁)＝...＝span(H_k,mF_m)＝...＝span(H_k,MF_M)

where K is 1,2, …, K, span (a) denotes the subspace spanned by the column vectors of matrix a.

The step S4 specifically includes the following steps:

s41, calculating a transmitter precoding matrix F received by the receiver_mProcessed signal level S_mAnd post-coding matrix G via the receiver_mProcessed signal level

S42, definition of all D2D-P_mSignal level mean square error sum_MSEThe following were used:

${\mathrm{\ϵ}}_{MSE}=\underset{m=1}{\overset{M}{\Σ}}E\left\{\right||\stackrel{\‾}{S_m}-S_m|{|}^2\}=\underset{m=1}{\overset{M}{\Σ}}E\left\{\right||{G_m}^H{S}_m-S_m|{|}^2\}$

the optimization problem is solved using the lagrangian multiplier method as follows:

$\begin{array}{cc}\underset{G_m,F_m}{\min }& {\mathrm{\ϵ}}_{MSE}\\ s.t.& \left|\right|F_m|{|}_F^2=P_m\end{array}$

wherein, E represents the value of the expected value,f norm, P, representing matrix X_mIs D2D-P_mThe power of the transmission is set to be,p is the total transmit power of all D2D-ps.

In the step S41, the transmitter pre-codes the matrix F_mProcessed signal level S_mThe following formula is specifically calculated:

$S_m=\sqrt{P_m}{H}_{m,m}{F}_m{Z}_m+\underset{j=1,j\≠m}{\overset{M}{\Σ}}\sqrt{P_j}{H}_{m,j}{F}_j{Z}_j+n_m$

wherein, P_mIs D2D-P_mTransmission power of the transmitter, H_m,mIs D2D-P_mN-row, N-column channel matrix, H, from transmitter to receiver_m,jIs D2D-P_jTransmitter to D2D-P_mN-row, N-column channel matrix, N, of a receiver_mIs D2D-P_mAmbient noise received by the receiver.

The step S42 specifically includes the following steps:

s420, introducing a Lagrange multiplier lambda_mTo obtain the Lagrangian function:

$L(F_m,G_m,{\mathrm{\λ}}_m)={\mathrm{\ϵ}}_{MSE}+{\mathrm{\λ}}_m\left(\right|\left|F_m\right|{|}_F^2-P_m)$

wherein,_MSEsee definition of S42.

S421 for G in Lagrange function respectively_m、F_mTaking the partial derivative and making the partial derivative zero, we get equation (1) (2):

$F_m={(\underset{j=1}{\overset{M}{\Σ}}{H}_{j,m}{G}_j{G}_j^H{H}_{j,m}^H+{\mathrm{\λ}}_{m}I)}^{-1}{H}_{m,m}^H{G_m}^H---\left(1\right)$

$G_m={F_m}^H{H_{m,m}}^H{(\underset{j=1}{\overset{M}{\Σ}}{H}_{m,j}{F}_j{F}_j^H{\left(H_{m,j}\right)}^H+{\mathrm{\σ}}^{2}I)}^{-1}---\left(2\right)$

wherein M is 1,2, …, M, sigma²For ambient noise n_mAnd E { n }_mn_m ^H}＝σ²I, I is an N-order identity matrix;

s422, initializing a precoding matrix F_mObtaining a random matrix of N rows and d columns for the random matrix;

s423, calculating by the formula (2) to obtain a post-coding matrix G_m；

S424, substituting the formula (1) into the power limiting conditionFind lambda_m，λ_mNot less than 0, lambda_mSubstitution of formula (1), update F_m；

S425, calculating the sum of mean square errors_MSE；

S426, repeating the steps from the step 423 to the step 425 until_MSEConverge to obtain G_mAnd F_m。

In the S5, D2D-P_mCommunication SINR threshold value omega_thComprises the following steps: the cellular users participating in the communication measure the SINR of the local received signal and send the signal to the cellular base station through a feedback channel, and the cellular base station sets the minimum SINR to be a D2D-P communication threshold value omega_thThe local received signal comprises all interference of D2D-P to cellular users, and signals sent by the base station to all cellular users; a cellular subscriber receives signals transmitted by the base station to all cellular subscribers, including desired signals and undesired signals, which are considered interference.

In S6, P_mThe calculation formula is as follows:

P_m＝β_m(μ/γ_m-1)⁺

wherein mu is the level of water injection and satisfiesγ_mIs D2D-P_mThe channel gain of (a) is determined,p is the total transmit power of all D2D-P, function (x)⁺Max (x,0) denotes taking the larger of the real numbers x and 0.

The communication method is applied to the cellular network shown in fig. 1, and the steps are as follows:

(1) setting a cellular Base Station (BS) in a communication scenario₀) 2 cellular subscribers (CU)₁、CU₂) And 2 pairs of D2D-P;

the cellular users and the D2D-P adopt multiple antennas, and the number of the transmitting antennas and the number of the receiving antennas of the cellular users and the D2D-P are both set to be 2;

D2D-P_mthe signal vector transmitted by the transmitter to the receiver is a matrix Z with 2 rows and 1 column_mM is 1 or 2;

(2) note D2D-P_mTo CU_kThe channel matrix of (k 1 or 2) is 2 rows and 2 columns of H_k,m，D2D-P_mThe precoding matrix of (2) rows and (2) columns F_m. Mixing D2D-P_m(m is 1,2) to CU_kInterference H of_k,mF_mAlign to CU_kOn the same signal subspace of the receiving end, the following is shown:

span(H_1,1F₁)＝span(H_1,2F₂)

span(H_2,1F₁)＝span(H_2,2F₂)

wherein span (A) represents the subspace of the column vector expansion of matrix A; f can be obtained from the two constraints_mThe solution set of (1);

(3) note CU_k(k 1 or 2) after reception of signalSetting the coding matrix as 2 rows and 2 columns of W_k. Designing a post-coding matrix W_kOrthogonal to D2D-P_mFor CU_kOf the interference channel matrix H_k,mF_m(m ═ 1 or 2), as follows:

W_k＝Null(H_k,mF_m),m＝1,2

where B ═ null (a), denotes that matrix B is orthogonal to matrix a;

(4) note D2D-P_mThe post-coding matrix of the receiving end is G with 2 rows and 2 columns_m. Obtaining the minimum D2D-P by adopting an interference alignment algorithm based on the minimum mean square error_m(m 1 or 2) post-coding matrix G of mean square error₁，G₂And a precoding matrix F₁，F₂The steps are as follows:

a. for G in the Lagrangian function respectively_m、F_m(m ═ 1 or 2) partial derivatives are taken and their partial derivatives are made zero, yielding equations (1) (2):

$F_m={(\underset{j=1}{\overset{M}{\Σ}}{H}_{j,m}{G}_j{G}_j^H{H}_{j,m}^H+{\mathrm{\λ}}_{m}I)}^{-1}{H}_{m,m}^H{G_m}^H---\left(1\right)$

$G_m={F_m}^H{H_{m,m}}^H{(\underset{j=1}{\overset{M}{\Σ}}{H}_{m,j}{F}_j{F}_j^H{\left(H_{m,j}\right)}^H+{\mathrm{\σ}}^{2}I)}^{-1}---\left(2\right)$

where m is 1 or 2, σ²For ambient noise n_mThe variance of (a);

b. initializing a precoding matrix F_mA random matrix with 2 rows and 2 columns;

c. calculating by formula (2) to obtain a post-coding matrix G_m；

d. Substituting equation (1) into the power limiting conditionFind lambda_m(λ_mNot less than 0), lambda is added_mSubstituting equation (1) to update F_m；

e. Calculating mean square error_MSE；

f. Repeating the steps c, d and e until_MSEConverge to obtain G_m，F_mNamely, the solution is obtained;

(5) according to a precoding matrix F_m(m is 1 or 2), and the channel gain γ of D2D-Pm is calculated_mAs follows:

${\mathrm{\γ}}_m=\frac{1}{\left|\right|F_m|{|}^2},m=1,2$

(6) measuring local received signal by cellular user participating in communicationAnd sent to the BS via a feedback channel₀From BS₀The minimum SINR is set as a D2D-P communication threshold omega_th. Then adopting hard decision to judge D2D-P_mWhether to access a cellular network, using the reference β_mExpressed, as follows:

${\mathrm{\&beta;}}_m=\left\{\begin{array}{c}1,{\mathrm{SINR}}_{D2Dm}<{\mathrm{\&omega;}}_{th}\\ 0,{\mathrm{SINR}}_{D2Dm}\&GreaterEqual;{\mathrm{\&omega;}}_{th}\end{array}\right.,m=1,2$

wherein, the SINR_D2DmRepresents D2D-P_mβ_mSetting the value to 0, indicating D2D-P_mCan not be connectedInto a cellular network β_mSetting the value to 1, representing D2D-P_mAccess to a cellular network;

(7) according to gamma_mAnd β_mAllocating D2D-P according to a modified water-filling power allocation algorithm_mTransmit power P_mAs follows:

P_m＝β_m(μ/γ_m-1)⁺,m＝1,2

wherein mu is the level of water injection and satisfiesFunction (x)⁺Max (x,0) represents the maximum operation of the real numbers x and 0.

Claims (7)

1. A D2D-P multiplexing cellular network communication method for improving spectrum utilization rate is characterized by comprising the following steps:

s1, establishing a cellular network, wherein the cellular network comprises a cellular base station and K cellular user CUs_kAnd M pairs of device-to-device user pairs D2D-P_mK is 1,2, …, K, M is 1,2, …, M, said D2D-P_mThe cellular user, the transmitter and the receiver are respectively provided with N transmitting antenna numbers and N receiving antenna numbers, and a signal vector Z sent from the transmitter to the receiver_mIs D row, 1 column, D2D-P_mTo CU_kOf the channel matrix H_k,mN rows and N columns;

s2, according to H_k,mObtaining D2D-P by interference alignment_mN rows and d columns precoding matrix F_mThe solution set of (1);

s3, calculating D2D-P_mFor each CU_kInterference matrix H of_k,mF_mDesigned to be orthogonal to H_k,mF_mN rows and d columns of each cellular user postcode matrix W_k；

S4, obtaining all D2D-P by interference alignment method based on minimum mean square error_mTransmitter precoding matrix F_mAnd receiver postcoding matrix G_mAnd performs cellular network communication to acquire each cellular subscriber CU_kThe signal to interference plus noise ratio (SINR);

s5, setting D2D-P_mSINR threshold ω_thIf D2D-P_mSINR of less than ω_thThen the D2D-P is added_mAccess the cellular network and set β_mValue 1, otherwise set β_mA value of 0;

s6, precoding matrix F according to the transmitter_mAnd β_mValue, using improved water injection power distribution method for all D2D-P_mAllocating transmission power P_m；

And S7, performing cellular network communication according to the matrix calculation result and the power distribution result of the steps S2-S6.

2. The D2D-P multiplexing cellular network communication method for improving spectrum utilization according to claim 1, wherein the step S2 specifically comprises: all D2D-P_mFor CU_kInterference matrix H of_k,mF_mAlign to the CU_kOn the same signal subspace of the receiving end, the following specific equations are provided:

span(H_k,1F₁)＝...＝span(H_k,mF_m)＝...＝span(H_k,MF_M)

where K is 1,2, …, K, span (a) denotes the subspace spanned by the column vectors of matrix a.

3. The D2D-P multiplexing cellular network communication method for improving spectrum utilization according to claim 1, wherein the step S4 specifically includes the steps of:

s41, calculating a transmitter precoding matrix F received by the receiver_mProcessed signal level S_mAnd S_mPost-coding matrix G via receiver_mSignal level obtained after processing

S42, definition of all D2D-P_mSignal level mean square error sum_MSEThe following were used:

${\mathrm{\&epsiv;}}_{MSE}=\underset{m=1}{\overset{M}{\&Sigma;}}E\left\{\right||\stackrel{\&OverBar;}{S_m}-S_m|{|}^2\}=\underset{m=1}{\overset{M}{\&Sigma;}}E\left\{\right||{G_m}^H{S}_m-S_m|{|}^2\}$

the optimization problem is solved using the lagrangian multiplier method as follows:

$\underset{G_m,F_m}{min}{\mathrm{\&epsiv;}}_{MSE}$

$s.t.\left|\right|F_m|{|}_{Fm}^2=P_m$

wherein E {. represents the mathematical expectation, | | | X | | ceiling²The square of the norm of the matrix X is represented,f norm square, P, representing matrix X_mIs D2D-P_mAnd satisfyP is the total transmit power of all D2D-ps.

4. The D2D-P multiplexing cellular network communication method for improving spectrum utilization according to claim 3,wherein in step S41, the transmitter precodes matrix F_mProcessed signal level S_mThe following formula is specifically calculated:

$S_m=\sqrt{P_m}{H}_{m,m}{F}_m{Z}_m+\underset{j=1,j\&NotEqual;m}{\overset{M}{\&Sigma;}}\sqrt{P_j}{H}_{m,j}{F}_j{Z}_j+n_m$

wherein, P_mIs D2D-P_mTransmission power of the transmitter, H_m,mIs D2D-P_mN-row, N-column channel matrix, H, from transmitter to receiver_m,jIs D2D-P_jTransmitter to D2D-P_mN-row, N-column channel matrix, N, of a receiver_mIs D2D-P_mAmbient noise received by the receiver.

5. The D2D-P multiplexing cellular network communication method for improving spectrum utilization rate according to claim 3, wherein the step S42 specifically includes the steps of:

s420, introducing a Lagrange multiplier lambda_mTo obtain the Lagrangian function:

$L(F_m,G_m,{\mathrm{\&lambda;}}_m)={\mathrm{\&epsiv;}}_{MSE}+{\mathrm{\&lambda;}}_m\left(\right|\left|F_m\right|{|}_F^2-P_m)$

wherein,_MSEis the sum of the mean square errors of the signal levels;

s421 for G in Lagrange function respectively_m、F_mCalculating partial derivatives, and making the partial derivatives zero to obtain equations (1), (2):

$F_m={(\underset{j=1}{\overset{M}{\&Sigma;}}{H}_{j,m}{G}_j{G}_j^H{H}_{j,m}^H+{\mathrm{\&lambda;}}_{m}I)}^{-1}{H}_{m,m}^H{G_m}^H---\left(1\right)$

$G_m={F_m}^H{H_{m,m}}^H{(\underset{j=1}{\overset{M}{\&Sigma;}}{H}_{m,j}{F}_j{F}_j^H{\left(H_{m,j}\right)}^H+{\mathrm{\&sigma;}}^{2}I)}^{-1}---\left(2\right)$

wherein M is 1,2, …, M, sigma²For ambient noise n_mAnd E { n }_mn_m ^H}＝σ²I, I is an N-order identity matrix;

s422, initializing a precoding matrix F_mIs a random matrix;

s423, calculating by the formula (2) to obtain a post-coding matrix G_m；

S424, substituting the formula (1) into the power limiting conditionFind lambda_mLambda of a handle_mSubstitution of formula (1), update F_m；

S425, calculating all D2D-P_mSignal level mean square error sum_MSE；

S426, repeating the steps from the step 423 to the step 425 until_MSEConverge to obtain G_mAnd F_m。

6. The D2D-P multiplexing cellular network communication method for improving spectrum utilization rate of claim 1, wherein in S5, D2D-P_mCommunication SINR threshold value omega_thComprises the following steps: the cellular users participating in the communication measure the SINR of the local received signal and send the signal to the cellular base station through a feedback channel, and the cellular base station sets the minimum SINR to be a D2D-P communication threshold value omega_th。

7. The method of claim 1, wherein the D2D-P multiplexing cellular network communication method for improving spectrum utilization rate is characterized in thatIn the S6, the improved water injection power distribution method solves D2D-P_mTransmission power P_mThe calculation method comprises the following steps:

P_m＝β_m(μ/γ_m-1)⁺

wherein mu is the level of water injection and satisfiesγ_mIs D2D-P_mThe channel gain of (a) is determined,p is the total transmit power of all D2D-P, function (x)⁺Max (x,0) denotes taking the larger of the real numbers x and 0.