Summary of the invention
The present invention is directed to the deficiencies in the prior art, the optimum transmit-receive combination processing method of communication between devices under a kind of mobile communications network is provided, thereby the mean square error of the reception signal that the specific implementation of combined optimization can be by making mobile radio network link and D2D link minimizes and reduces bit error rate, and that perhaps optimizes whole system makes it maximization with speed.
The technical solution used in the present invention is: the optimum transmit-receive combination processing method of communication between devices under a kind of mobile communications network, and the method is carried out according to the following steps:
1) D2D (Device-to-Device) transmission user UE1 (User Equipment) and D2D reception user UE2 have respectively N
1Root transmitting antenna and M
1The root reception antenna, the base station has N
2The root transmitting antenna, network user UE3 has M
2The root reception antenna.The transmitted power that D2D sends user and base station is respectively P
1, P
2, they send respectively multi-stream data x
1And x
2(dimension is respectively S
1* 1 and S
2* 1) gives separately receiver.S
1And S
2The data fluxion that represents respectively D2D link and mobile radio network link transmission.
2) D2D link and mobile radio network link adopt nonopiate mode to share running time-frequency resource, namely D2D equipment between physical channel and certain mobile radio network user's the physical resource of communication overlapping.In TDD (Time Division Duplexing) system, realize optimum transmitting-receiving design in order to make the base station obtain complete channel information, the base station can obtain the base station to the down channel H of UE3 by uplink channel estimation
2And the base station is to the descending interference channel H of UE2
2,1By above-mentioned identical channel estimating mode, UE1 can obtain it equally to the transmission channel H of UE2
1And the interference channel H between it and the UE3
1,2Last UE1 is with H
1And H
1,2Feed back to the base station.
3) base station receives signal mean square error reduction bit error rate or the optimization of maximum channel channel capacity criterion base station, the pre-coding matrix of UE1 and the receiving matrix of UE2, UE3 according to the four complete class channel informations that obtain by minimizing.Because the protruding problem of above-mentioned optimization problem right and wrong and do not have closed solutions is so this patent provides two kinds of optional iterative algorithms.Be convenient narration, will minimize reception signal mean square error iterative algorithm and be called algorithm one, and maximum channel capacity algorithm is called algorithm two.The iterative calculation method of algorithm one is as follows:
Step 1: make iterations variable n=0, according to transmission channel H
1And H
2The singular value decomposition initializes sends pre-coding matrix
U=1,2; Subscript u is the variable of sign link, and wherein u=1 and u=2 represent respectively D2D link (communication link between UE1 and the UE2) and mobile network's down link (base station is to the communication link of UE3).
Then step 2:n=n+1 calculates the receiving matrix of the n+1 time iterative process link u according to following formula (2)
Step 3:
step 2 is calculated
Formula (3) is tried to achieve parameter below the substitution power constraint condition
Wherein
That guaranteed output constraints is set up and the Lagrange's multiplier of introducing;
Step 4: with what calculate in
step 2 and the
step 3
With
Formula below the substitution (1) can calculate the transmission pre-coding matrix in the iterative process the n+1 time
Step 5: repeating step 2 to step 4 until
With
Convergence.
Formula (1) all is variable and the u of sign link to the middle subscript u of formula (3) and m, m ∈ 1,2}, u ≠ m, and n represents the iterations variable, the conjugate transpose operation of capitalization H representing matrix, I representation unit battle array.
With
Represented respectively matrix
With
T element on the leading diagonal.Wherein,
With
Be respectively
The diagonal matrix of feature decomposition and unitary matrice.
The iterative calculation method of algorithm two is as follows:
Step 1: make iterations variable n=0, select enough little positive number τ and thresholding (be generally minimum positive number, for example get 0.001), according to transmission channel H
1And H
2The singular value decomposition initializes sends pre-coding matrix
And receiving matrix
And formula (4) below their substitutions obtained the Initial Channel Assignment capacity and be designated as cap (0);
Then step 2:n=n+1 calculates in the n+1 time iteration according to (5) formula quadratic programming and upgrades vectorial z; The expression formula of z is
Wherein,
With
Represent respectively link u pre-coding matrix and the receiving matrix updating value in n+1 the iterative process in ground; U=1,2 represents respectively D2D link (communication link between UE1 and the UE2) and mobile network's down link (base station is to the communication link of UE3);
Represent stretching computing, T representing matrix transposition.
Step 3: utilize the renewal vector that obtains in the
step 2 and introduce linear search parameter β, β changes at interval [0,1] neutral line, simultaneously note
With
And their substitution formulas (4) are calculated the cap (n+1, β) that contains ginseng, finally try to achieve the β of maximization cap (n+1, β)
*
Step 4: upgrade
With
And the channel capacity that obtains optimum in the n+1 iterative process is designated as cap (n+1)=cap (n+1, β
*).
Step 5: repeating step 2 is to step 4 until cap (n+1)-cap (n)≤thresholding;
Step 6: last, according to the power constraint condition to W
uLinear weighted function;
The computing formula of maximum channel capacity criterion shown in following formula (4), below formula (5) be the approximate expression of formula (4) and for quadratic programming problem;
(4)
Wherein, subscript u and m are variable and the u of sign link in the formula (4), m ∈ { 1,2}, u ≠ m, the conjugate transpose operation of capitalization H representing matrix, I representation unit battle array.w
U, kAnd f
U, kRespectively to send pre-coding matrix W
uWith receiving matrix F
uThe k column vector; ρ
uBe the transmitted power constraint factor of link u, the guaranteed output perseverance is P
u Be the reception Signal to Interference plus Noise Ratio of k the data flow of link u, can be with the following protruding optimization problem that is converted into of the optimization problem equivalence of (4) formula with ignoring behind the higher order term with the single order polynomial approximation after its Taylor expansion:
s.t. Qz=e (5)
-τ1≤z≤τ1
For convenience of description, some has been merged into following listed intermediate variable in the formula (5):
e=[P
1/ρ
1 P
2/ρ
2]
T
p
U, kIn the expression formula
g
X, u, kAnd g
Y, u, kIt is as follows,
In the formula (7)
With
Be respectively
Molecule and denominator, variable a
U, i, b
U, i, c
mAnd d
U, kBe defined as follows
Capable vector in the formula (6) among the matrix Q is
Beneficial effect: 1) the inventive method has considered that more all sidedly the base station sends the user to the interference of mobile radio network link to interference and the D2D of D2D link.Take full advantage of all transmission channels and interference channel information, transmission pre-coding matrix and the receiving matrix of combined optimization mobile radio network link and D2D link.
2) adopting the transmission pre-coding matrix that calculates in the inventive method and receiving matrix to reach to minimize the residential quarter to receive the signal mean square error receives bit error rate and and maximizes two links and target speed to reduce.Performance to real system improves a lot.
Embodiment
Below in conjunction with accompanying drawing the present invention is further described.
As shown in Figure 1: implementation step of the present invention is as follows:
1) D2D (Device-to-Device) transmission user UE1 (User Equipment) and D2D reception user UE2 have respectively N
1Root transmitting antenna and M
1The root reception antenna, the base station has N
2The root transmitting antenna, network user UE3 has M
2The root reception antenna.The transmitted power that D2D sends user and base station is respectively P
1, P
2, they send respectively multi-stream data x
1And x
2(dimension is respectively S
1* 1 and S
2* 1) gives separately receiver.S
1And S
2The data fluxion that represents respectively D2D link and mobile radio network link transmission.
2) D2D link and mobile radio network link adopt nonopiate mode to share running time-frequency resource, namely D2D equipment between physical channel and certain mobile radio network user's the physical resource of communication overlapping.In TDD (Time Division Duplexing) system, realize optimum transmitting-receiving design in order to make the base station obtain complete channel information, the base station can obtain the base station to the down channel H of UE3 by uplink channel estimation
2And the base station is to the descending interference channel H of UE2
2,1By above-mentioned identical channel estimating mode, UE1 can obtain it equally to the transmission channel H of UE2
1And the interference channel H between it and the UE3
1,2Last UE1 is with H
1And H
1,2Feed back to the base station.
3) base station receives signal mean square error reduction bit error rate or the optimization of maximum channel channel capacity criterion base station, the pre-coding matrix of UE1 and the receiving matrix of UE2, UE3 according to the four complete class channel informations that obtain by minimizing.Because the protruding problem of above-mentioned optimization problem right and wrong and do not have closed solutions is so this patent provides two kinds of optional iterative algorithms.U=1, u=2 represent respectively D2D link and mobile radio network link.Be convenient narration, will minimize reception signal mean square error iterative algorithm and be called algorithm one, as shown in Figure 2, and maximum channel capacity algorithm is called algorithm two, as shown in Figure 3.The iterative calculation method of algorithm one is as follows:
Step 1: make iterations variable n=0, according to transmission channel H
1And H
2The singular value decomposition initializes sends pre-coding matrix
U=1,2; Subscript u is the variable of sign link, and wherein u=1 and u=2 represent respectively D2D link (communication link between UE1 and the UE2) and mobile network's down link (base station is to the communication link of UE3).
Then step 2:n=n+1 calculates the receiving matrix of the n+1 time iterative process link u according to following formula (2)
Step 3:
step 2 is calculated
Formula (3) is tried to achieve parameter below the substitution power constraint condition
Wherein
That guaranteed output constraints is set up and the Lagrange's multiplier of introducing;
Step 4: with what calculate in
step 2 and the
step 3
With
Formula below the substitution (1) can calculate the transmission pre-coding matrix in the iterative process the n+1 time
Step 5: repeating
step 2 to step 4 until
With
Convergence.
Formula (1) all is variable and the u of sign link to the middle subscript u of formula (3) and m, m ∈ 1,2}, u ≠ m, and n represents the iterations variable, the conjugate transpose operation of capitalization H representing matrix, I representation unit battle array.
With
Represented respectively matrix
With
T element on the leading diagonal.Wherein,
With
Be respectively
The diagonal matrix of feature decomposition and unitary matrice.
The iterative calculation method of algorithm two is as follows:
Step 1: make iterations variable n=0, select enough little positive number τ and thresholding (be generally minimum positive number, for example get 0.001), according to transmission channel H
1And H
2The singular value decomposition initializes sends pre-coding matrix
And receiving matrix
And formula (4) below their substitutions obtained the Initial Channel Assignment capacity and be designated as cap (0);
Then step 2:n=n+1 calculates in the n+1 time iteration according to following (5) formula quadratic programming and upgrades vectorial z; The expression formula of z is
Wherein,
With
Represent respectively link u pre-coding matrix and the receiving matrix updating value in n+1 the iterative process in ground; U=1,2 represents respectively D2D link (communication link between UE1 and the UE2) and mobile network's down link (base station is to the communication link of UE3);
Represent stretching computing, T representing matrix transposition.
Step 3: utilize the renewal vector that obtains in the
step 2 and introduce linear search parameter β, β changes at interval [0,1] neutral line, simultaneously note
With
And their substitution formulas (4) are calculated the cap (n+1, β) that contains ginseng, finally try to achieve the β of maximization cap (n+1, β)
*
Step 4: upgrade
With
And the channel capacity that obtains optimum in the n+1 iterative process is designated as cap (n+1)=cap (n+1, β
*).
Step 5: repeating step 2 is to step 4 until cap (n+1)-cap (n)≤thresholding;
Step 6: last, according to the power constraint condition to W
uLinear weighted function;
The computing formula of maximum channel capacity criterion is suc as formula shown in following (4), below formula (5) be the approximate expression of formula (4) and be quadratic programming problem;
(4)
Wherein, subscript u and m are variable and the u of sign link in the formula (4), m ∈ { 1,2}, u ≠ m, the conjugate transpose operation of capitalization H representing matrix, I representation unit battle array.w
U, kAnd f
U, kRespectively to send pre-coding matrix W
uWith receiving matrix F
uThe k column vector; ρ
uBe the transmitted power constraint factor of link u, the guaranteed output perseverance is P
u Be the reception Signal to Interference plus Noise Ratio of k the data flow of link u, can be with the following protruding optimization problem that is converted into of the optimization problem equivalence of (4) formula with ignoring behind the higher order term with the single order polynomial approximation after its Taylor expansion:
s.t. Qz=e (5)
-τ1≤z≤τ1
For convenience of description, some has been merged into following listed intermediate variable in the formula (5):
e=[P
1/ρ
1 P
2/ρ
2]
T
p
U, kIn the expression formula
g
X, u, kAnd g
Y, u, kIt is as follows,
In the formula (7)
With
Be respectively
Molecule and denominator, variable a
U, i, b
U, i, c
mAnd d
U, kBe defined as follows
Capable vector in the formula (6) among the matrix Q is
The above only is preferred implementation of the present invention; be noted that for those skilled in the art; under the prerequisite that does not break away from the principle of the invention, can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.