CN104717755A - Downlink frequency spectrum resource distribution method with D2D technology introduced in cellular network - Google Patents

Abstract

The invention discloses a downlink frequency spectrum resource distribution method with the D2D technology introduced in a cellular network. The method includes the following steps that (1) in the downlink time slot, an interference limited area (ILA) of cellular users is used for reducing the inference to the cellular users by D2D users, and thus the normal communication of the cellular users can be guaranteed; (2) frequency spectrum resources are distributed to D2D communication links by using the sum capacity maximization of cellular links and D2D links in the system as the target; (3) when different D2D links are distributed with the same frequency spectrum resource, and a heuristic optimization algorithm is used by a base station to conduct frequency spectrum resource redistribution on the D2D links distributed with the same frequency spectrum resource in order to avoid the interference between the D2D links.

Description

The down frequency spectrum resources distribution method of D2D technology is introduced in a kind of cellular network

Technical field

The invention belongs to communication technical field, relate to the frequency spectrum resource allocation method introducing D2D technology in a kind of cellular network.

Background technology

Along with the development of mobile communication, 3G (Third Generation) Moblie is commercial.Industry just drops into more makes great efforts in the development of next generation wireless communication network, the Long Term Evolution (LTE/LTE-A) of such as 3GPP.LTE-A, as one of the candidate criteria of forth generation mobile communication system IMT-Advanced, meets the requirement of compatibility, hardware circuit solution and the spectrum efficiency that IMT-A proposes to a certain extent.Meanwhile, the two-forty of wireless cellular communication network, Large Copacity and higher service quality (QoS) have been inexorable trend, how more effectively to use limited bandwidth resources to realize WiMAX and seem particularly important.The local service of fast development in especially current mobile Internet, such as video/music is shared, also in the urgent need to introducing new technology to support in existing Cellular Networks.Traditional cellular mobile communication networks is all centerized fusion, and namely two terminal equipments are adjacent very near, and the communication between terminal equipment still must be undertaken by base station, and namely under certain scene, its resource utilization is not high.

In order to improve frequency spectrum resource service efficiency, reduce the load of Cellular Networks, obtain higher power system capacity, terminal direct connection (Device-to-Device communication, the D2D) technical research under cellular network comes into one's own day by day.Under base station controls D2D link terminal between communication have two kinds of patterns, a kind of is traditional communication pattern, and another kind directly carries out data communication between terminal, thus reduces the taking of interface-free resources, and improves system throughput.Simultaneously due to straight-through between terminal, do not need to forward through base station, can communication delay be reduced.Carry out short haul connection between D2D terminal in addition, transmitted power comparatively traditional communication is low, can save final energy again.

The application scenarios of terminal direct connection technology mostly is the type of local service, such as data multicast business and local file shared service.In multi-case data business, the supplier of service, organizer, can utilize the D2D communication technology, sends identical data content, immediately reliably complete service to participant.In addition, the available business of D2D technology also comprises the multiple person cooperational game, mobile advertisement service, friend-making business, inter-vehicular communication, mobile relay etc. in mobile status.

With can support compared with similar traffic (WLAN of unauthorized frequency range, bluetooth), D2D communication in cellular communication system is under the control of base station, use the authorized frequency bands resource of base station assigns, base station can control system interference level to obtain higher data transfer rate, simultaneously without the need to carrying out loaded down with trivial details manual pairings and access point setting as in WLAN and bluetooth, thus improve Consumer's Experience, be convenient to promoting service.

At present for the research of the down frequency spectrum resources assignment problem of the cellular system of introducing D2D communication, a kind of method of usual employing calculates the power system capacity that D2D communication link uses different spectral resource under three kinds of different communication modes respectively, the size of the power system capacity under Three models is compared, selection capacity maximum as communication pattern, simultaneously give D2D communication link distribute the frequency spectrum resource making capacity reach maximum.Another method the frequency spectrum resource in cellular cell is divided into two parts according to position, center of housing estate frequency spectrum and cell edge frequency spectrum.Such as, when D2D communication link is positioned at cell edge, allocations of edge frequency spectrum is multiplexing to D2D link; On the contrary, when D2D communication link is positioned at inside, cellular cell, distributing center frequency spectrum is multiplexing to D2D link.

Summary of the invention

The object of the present invention is to provide the down frequency spectrum resources distribution method introducing D2D technology in a kind of cellular network, ensure be re-used frequency spectrum resource phone user's proper communication while, for D2D link assignment down frequency spectrum resources, the method effectively can reduce the mutual interference between cellular link and D2D link, the capacity of elevator system.The present invention effectively raises actual operation, and signaling is simple simultaneously, complexity is low, reduces overhead.

For achieving the above object, present invention employs following technical scheme.

Introduce a down frequency spectrum resources distribution method for D2D technology in cellular network, concrete steps are: (1) sets up D2D communication link, assuming that: D2D link transmissions end D _tconstant transmitting power P is adopted in the process of communication _dtransmission information, and the channel between D2D user and phone user only considers large scale fading effect; If distance D _twhen the frequency spectrum resource of nearer phone user is multiplexing by D2D link, user D _tto the interference I of phone user _dCexceed phone user and can bear interference threshold value, as phone user and D _tdistance when exceeding certain length value, the interference I that phone user receives _dClower than interference threshold value; (2) at descending time slot, the frequency spectrum resource of the multiplexing cellular link of D2D link, D2D user produces interference to phone user, utilizes the interference-limited region of phone user to reduce D2D user to the interference of phone user, thus ensures the proper communication of phone user; (3) with cellular link and D2D link sum maximum capacity for target distributes frequency spectrum resource to D2D communication link; (4) when different D2D link assignment is to identical frequency spectrum resource, the D2D link being assigned to same spectrum resources is carried out to the reallocation of frequency spectrum resource.

As the preferred embodiments of the present invention, in described step (2), base station utilizes the transmitting power of D2D user and path loss model to calculate the interference-limited region of phone user, the frequency spectrum resource of the phone user in interference-limited region can not be multiplexing by D2D user, and the center of circle in described interference-limited region is D2D transmitting terminal D _t, radius is: wherein, P _dfor the transmitting power that D2D user is constant, c is path loss coefficient, N ₀for noise power, δ _cfor the threshold value of the interference-to-noise ratio that phone user receives.

As the preferred embodiments of the present invention, the concrete steps of described step (3) are: first, under downstream spectrum multiplexer mode, calculate the letter drying ratio of phone user and D2D user with then according to the dry ratio of the letter of correspondence, the capacity of respective link is calculated with finally carry out Resourse Distribute with the maximum target that turns to of capacity sum of cellular link and D2D link, wherein, maximize with the formula with the capacity sum of cellular link and D2D link represent, must meet simultaneously cellular link and D2D link can proper communication and D2D link at most can only the frequency spectrum resource of a multiplexing cellular link.

As the preferred embodiments of the present invention, maximizing to the capacity sum of cellular link and D2D link the method solved is: first by formula be reduced to: wherein, α _ifor the resource of the multiplexing phone user of D2D user, for the channel coefficients between base station and D2D user, P _bfor the transmitted power of base station, L _bDfor the link range of base station and D2D user, α is path loss index, for the frequency spectrum resource that the phone user in interference-limited region takies; The solving result of the result of Resourse Distribute represents as follows: wherein, i ^*for optimum resource index; Because base station can obtain the channel information of all channels be attached thereto, therefore, base station obtains channel coefficients during the multiplexing different spectral resource of D2D link, distributes to D2D link with the frequency spectrum resource that spectral channel coefficient is minimum.

As the preferred embodiments of the present invention, the concrete steps of step (4) are: when occurring that m bar D2D link assignment is to same resource i ^*situation time, adopt following methods to distribute again frequency spectrum resource, ensure that m bar D2D link can proper communication, wherein, m>=2; (4.1) due to m ?the non-interfering D2D link of s bar can continue to use frequency spectrum resource i ^*, therefore, then the process of sub-distribution represents with following formula: wherein, _jrepresent the sequence number of D2D link, β _i,j∈ { 0,1}, β _i,j=1 expression sequence number is the multiplexing label of D2D link of j is the frequency spectrum resource of i; Need to meet base station is can proper communication after the D2D link reallocation frequency spectrum resource that mutually disturbs of S bar simultaneously, and a multiplexing at most cellular link resource of D2D link, ensure that the D2D link of interference mutually does not use identical frequency spectrum resource simultaneously; (4.2) to the equations in step (4.1), the result of frequency spectrum resource reallocation is obtained.

As the preferred embodiments of the present invention, the method for solving of step (4.2) is: redistribute resources is carried out to the D2D link that m bar is assigned to same spectrum resources in base station, the channel information of the receiving terminal of the base station that base station utilization obtains and D2D link judges the disturbed condition on every block frequency spectrum resource, and then the quality judging for different D2D link performance, utilize Given information to carry out scheduling of resource.

As the preferred embodiments of the present invention, the concrete method for solving of step (4.2) is: the channel information between the receiving terminal of the D2D link that the base station of acquisition and s bar are disturbed by (4.2.1) base station mutually i ∈ 1 ..., n}, j ∈ 1 ..., s} sorts from small to large, namely obtain the channel coefficient matrix of a s × n, to be base station arrange from small to large to the channel coefficients of D2D link receiving terminal for each provisional capital of this matrix; (4.2.2) suppose that u article of D2D link assignment has arrived i ^*frequency spectrum resource and be subject to other and be assigned to i ^*the interference of the D2D link of frequency spectrum resource, wherein, i ^*[u in representing matrix, 1] frequency spectrum resource, then u article of D2D link can not use [u, 1] resource, be now its preassignment frequency spectrum resource [u, 2], then judge whether this frequency spectrum resource [u, 2] can ensure that base station is can proper communication after the D2D link reallocation frequency spectrum resource that mutually disturbs of S bar, if met, enter step (4.2.3), if do not met, terminate frequency spectrum resource and distribute; (4.2.3) judge: whether (1) frequency spectrum resource [u, 2] is elected to be optimum frequency spectrum resource by the D2D link outside m bar according to channel coefficients is minimum; (2) judge frequency spectrum resource [u, 2] whether with [j, 2], j ∈ 1 ..., s}, j ≠ u is identical frequency spectrum resource; If all whether condition (1) and condition (2), then by frequency spectrum resource [u, 2] u article of D2D link is distributed to, if condition (1) is yes, then base station judges frequency spectrum resource, repeat step (4.2.1) to step (4.2.3), until give u article of D2D link assignment to the frequency spectrum resource meeting restrictive condition; If condition (1) is not for no and condition (2) is yes, then, Resourse Distribute is carried out according to the magnitude relationship of channel coefficients in base station.

As the preferred embodiments of the present invention, in step (4.2.3), the method that Resourse Distribute is carried out according to the magnitude relationship of channel coefficients in base station is: if then base station assigns frequency spectrum resource [u, 2] is to u article of D2D link; If base station judges frequency spectrum resource [u, 3], repeats step (4.2.1) to step (4.2.3), until give u article of D2D link assignment to the resource meeting restrictive condition.

Compared with prior art, the invention has the beneficial effects as follows:

The present invention is directed to the scene of the multipair D2D telex network existed in cellular network, propose the method for the multiplexing phone user's down frequency spectrum resources of a kind of simple D2D user, D2D user is communicated by share spectrum resources.The inventive method utilizes the interference-limited regional coordination of phone user to reduce D2D user to the interference of phone user, carry out Resourse Distribute by what optimize the be re-used cellular link of frequency spectrum resource and D2D link with capacity, finally the D2D link being assigned to same spectrum resources is carried out to the reallocation of frequency spectrum resource.This method effectively can reduce the mutual interference between cellular link and D2D link, elevator system spectrum efficiency.Meanwhile, when this method increases for the quantity right as D2D user in cellular cell, algorithm complex is relatively low.

Accompanying drawing explanation

Fig. 1 is the Scene case that the inventive method is applied;

Power system capacity comparison diagram when Fig. 2 is the spacing difference of D2D user under different resource allocative decision;

Fig. 3 is power system capacity comparison diagram when D2D link transmissions end power is different under different resource allocative decision;

When Fig. 4 is interference-limited region difference under different resource allocative decision, D2D link is to the comparison diagram of the interference that cellular link produces;

Fig. 5 (a) be under different resource allocative decision D2D user to the CDF curve of the interference that phone user produces;

Fig. 5 (b) be under different resource allocative decision base station to the CDF curve of the interference that D2D user produces;

Embodiment

Below in conjunction with accompanying drawing, the present invention is described in further detail:

For the ease of understanding, the present invention, for the D2D communication network under lte-a system, illustrates in cellular network introducing D2D technology.

Below in conjunction with emulation and accompanying drawing, the present invention is described in detail.Specifically comprise the following steps: step (1): the determination of interference-limited region (ILA)

In system model Fig. 1, user D _twith D _rbetween set up D2D communication link, CUE ₁, CUE ₂..., CUE _nfor phone user, base station BS is D2D link assignment down frequency spectrum resources, according to the LTE system demand parameter that 3GPP TR25.913 defines, it is 20MHz that single subdistrict takies system bandwidth, each phone user takies t basic resource blocks (180KHz) (t=1,2,3, ..., n).Suppose D2D link transmissions end D _tconstant transmitting power P is adopted in the process of communication _dtransmission information, and the channel between D2D user and phone user only considers large scale fading effect.If distance D _twhen the frequency spectrum resource of nearer phone user is multiplexing by D2D link, then user D _tto the interference I of phone user _dCphone user can be exceeded and can bear interference threshold value, so as phone user and D _tdistance when exceeding certain length value, the interference I that phone user receives _dCcan then lower than interference threshold value.

In order to ensure D2D user to phone user's interference value within the scope of acceptable, the condition below the interference value demand fulfillment that phone user receives:

$\frac{I_{\mathrm{DC}}}{N_0}\≤{\mathrm{\δ}}_c---\left(1\right)$

Wherein, δ _crepresent the threshold value of the interference-to-noise ratio that phone user receives, when interference-to-noise ratio is greater than this threshold value, then phone user can not carry out proper communication, otherwise then passable; N ₀represent noise power.

Only consider large scale fading effect by the channel between D2D user and phone user, can obtain

I _DC＝P _D·c·(L _DC) ^-α(2)

Wherein, c represents path loss coefficient, L _dCrepresent D _tto the distance of phone user.

Formula (2) being updated to the interference radius that formula (1) can obtain the determined interference region of D2D transmitting terminal is

$L_{\mathrm{th}}={\left(\frac{P_D\·c}{N_0\·{\mathrm{\δ}}_c}\right)}^{1/\mathrm{\α}}---\left(3\right)$

With D2D transmitting terminal D _tfor the center of circle, with L _thborder circular areas for radius is the interference-limited region of phone user, the frequency spectrum resource that the phone user in this region takies d2D communication link can not be distributed to multiplexing.

Step (2): select optimum resource to distribute

Under downstream spectrum multiplexer mode, the Signal to Interference plus Noise Ratio that can obtain phone user and D2D user is with

${\mathrm{\γ}}_C^i=\frac{{\left|h_{C_i}\right|}^2{P}_B{L}_{C_i}^{-\mathrm{\α}}}{{\left|h_{{\mathrm{DC}}_i}\right|}^2{P}_D{L}_{D{C}_i}^{-\mathrm{\α}}+N_0}---\left(4\right)$

${\mathrm{\γ}}_{D2D}^i=\frac{{\left|h_D\right|}^2{P}_D{\mathrm{\ρ}}^{-\mathrm{\α}}}{{\left|h_{B_{i}D}\right|}^2{P}_B{L}_{\mathrm{BD}}^{-\mathrm{\α}}+N_0}---\left(5\right)$

Wherein, P _brepresent the transmitted power of base station, P _drepresent the signal transmitting power with the D2D link transmitting terminal of i-th multiplexing same spectrum resources of phone user, represent i-th channel coefficients between phone user and base station, represent the channel coefficients between base station and D2D user, represent the channel coefficients between D2D user and phone user, h _drepresent the channel coefficients of D2D communication link, represent i-th distance between phone user and base station, L _bDrepresent the link range of base station and D2D user, ρ represents the distance between the transmitting terminal of D2D link and receiving terminal, and α represents path loss index, N ₀represent white Gaussian noise power.

According to the Signal to Interference plus Noise Ratio of link, utilize Shannon channel capacity formula, corresponding link capacity can be obtained with

$r_C^i=B{\log }_2(1+{\mathrm{\γ}}_C^i)---\left(6\right)$

$r_{D2D}^i={B\log }_2(1+{\mathrm{\γ}}_{D2D}^i)---\left(7\right)$

Wherein, B represents the spectral bandwidth of cellular link.When carrying out Resourse Distribute, we wish that the link capacity obtained reaches maximum, and therefore, optimization aim is expressed as follows by we:

$\max \underset{i=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\α}}_i(r_C^i+r_{D2D}^i)---\left(8\right)$

$s.t.{\mathrm{\γ}}_C^i\≥{\mathrm{\γ}}_{\mathrm{thc}}---\left(9\right)$

${\mathrm{\γ}}_{D2D}^i\≥{\mathrm{\γ}}_{\mathrm{thd}}---\left(10\right)$

$\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\α}}_i\≤1;{\mathrm{\α}}_i\∈\left\{\mathrm{0,1}\right\}---\left(11\right)$

Formula (8) is resource allocation optimization target, object is the resource allocation result obtaining making link capacity maximum, restrictive condition (9) and (10) ensure that cellular link and D2D link can proper communications, formula (10) then limits a D2D link at most can only the frequency spectrum resource of a multiplexing cellular link, wherein α _i=1 represents the multiplexing CUE of D2D user _iresource, otherwise then not multiplexing.Above-mentioned optimization problem is actually typical mixed integer nonlinear programming (MINLP) problem, and the optimum solution of this optimization problem can be obtained by the method for traversal search, but algorithm complex is very high.And we introduce ILA ensure phone user telecommunication service quality after, when restrictive condition is constant, optimization aim (8) can be converted into:

$\max \underset{i\∉R_{{\mathrm{\δ}}_c}}{\overset{n}{\underset{i=1}{\mathrm{\Σ}}}}{\mathrm{\α}}_i\left(r_{D2D}^i\right)=\max \underset{i\∉R_{{\mathrm{\δ}}_c}}{\overset{n}{\underset{i=1}{\mathrm{\Σ}}}}{\mathrm{\α}}_i\left[B{\log }_2(1+\frac{{\left|h_D\right|}^2{P}_D{\mathrm{\ρ}}^{-\mathrm{\α}}}{{\left|h_{B_{i}D}\right|}^2{P}_B{L}_{\mathrm{BD}}^{-\mathrm{\α}}+N_0})\right]---\left(12\right)$

Can be drawn by formula (12), optimal solution there will not be the resource collection determined at ILA in.Further for optimization aim abbreviation can be obtained:

$\min \underset{i\∉R_{{\mathrm{\δ}}_c}}{\overset{n}{\underset{i=1}{\mathrm{\Σ}}}}{\mathrm{\α}}_i{\left|h_{B_{i}D}\right|}^2{P}_B{L}_{\mathrm{BD}}^{-\mathrm{\α}}---\left(13\right)$

The solution of formula (13) is the result of Resourse Distribute, and optimal solution can be expressed as:

$i^{*}=\underset{i\∉R_{{\mathrm{\δ}}_c}}{\underset{i\∈\{\mathrm{1,2},...,n\}}{\arg }}\min \left({\left|h_{B_{i}D}\right|}^2\right)---\left(14\right)$

In formula (14), i ^*represent optimum resource index, because base station can obtain the channel information of all channels be attached thereto, therefore, base station can obtain channel coefficients during the multiplexing different spectral resource of D2D link, thus selects the minimum frequency spectrum resource of spectral channel coefficient to distribute to D2D link.

Step (3): frequency spectrum resource is reallocated

In last point, base station completes according to formula (14) to be distributed the frequency spectrum resource of D2D link, but when there is many D2D links in community, there will be m (m>=2) bar D2D link assignment to same resource i ^*situation.Study for m bar D2D link assignment to the problem of same spectrum resources below.

When occurring that m (m>=2) bar D2D link assignment is to same resource i ^*situation time, if m bar D2D link continue use resource i* communicate, then likely cause between D2D link and mutually disturb.Therefore, need to distribute again frequency spectrum resource, ensure that m bar D2D link can proper communication.The redistribute resources of m bar D2D link can be represented with following optimizing process:

$\underset{{\mathrm{\β}}_{i,j}}{\max }\underset{i=1}{\overset{n}{\mathrm{\Σ}}}\underset{j=1}{\overset{m}{\mathrm{\Σ}}}{\mathrm{\β}}_{i,j}{B\log }_2(1+{\mathrm{\γ}}_{{D2D}_j}^i)---\left(15\right)$

Formula (15) represents, frequency spectrum resource distribution again carries out based on the capacity sum maximizing m bar D2D link.Wherein, j ∈ 1 ..., m}, represents the sequence number of D2D link, wherein, and β _i,j∈ { 0,1}, β _i,j=1 expression sequence number is the multiplexing label of D2D link of j is the frequency spectrum resource of i, otherwise then not multiplexing.

Carry out abbreviation to formula (15) can obtain:

$\underset{{\mathrm{\β}}_{i,j}}{\max }\{\underset{i=1}{\overset{n}{\mathrm{\Σ}}}\underset{j=1}{\overset{s}{\mathrm{\Σ}}}{\mathrm{\β}}_{i,j}B{\log }_2(1+{\mathrm{\γ}}_{{D2D}_j}^i)+\underset{j=m-s+1}{\overset{m}{\mathrm{\Σ}}}B(1+{\mathrm{\γ}}_{{D2D}_j}^{i^{*}})\}---\left(16\right)$

Section 1 in formula (16) in braces represent in m bar D2D link, the D2D link capacity sum of interference mutually, Section 2 represent non-interfering D2D link capacity sum in m bar link.

Non-interfering m-s bar D2D link can continue to use frequency spectrum resource i ^*, the further abbreviation of formula (16) is obtained:

$\underset{{\mathrm{\β}}_{i,j}}{\max }\underset{i=1}{\overset{n}{\mathrm{\Σ}}}\underset{j=1}{\overset{s}{\mathrm{\Σ}}}{\mathrm{\β}}_{i,j}{B\log }_2(1+{\mathrm{\γ}}_{{D2D}_j}^i)---\left(17\right)$

$\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\β}}_{i,j}\≤1,\∀j\∈\[1,s\]---\left(19\right)$

$\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\β}}_{i,j}\≤1,\∀i\∈\[1,n\]---\left(20\right)$

β _i，j∈{0，1} (21)

Wherein, restrictive condition (18) ensure that base station is can proper communication after the D2D link reallocation frequency spectrum resource that mutually disturbs of s bar, formula (19) and formula (20) ensure that a multiplexing at most cellular link resource of D2D link, ensure that the D2D link of interference mutually does not use identical frequency spectrum resource simultaneously.The result of frequency spectrum resource reallocation asks the solution of optimization aim (17) exactly, but be very difficult for the optimal solution of solving-optimizing target (17) this kind of MINLP problem, although traversal search can obtain optimal solution, but computation complexity is very high, and expense is very large operation time, but communication system has very strict requirement to time delay, therefore need to seek a kind of method for solving that complexity is lower under guarantee system system can obtain the prerequisite fully optimized.Propose a kind of heuristic value here to complete the reallocation of frequency spectrum resource, can prove that this algorithm optimizes systematic function to greatest extent again while reducing computation complexity by simulation analysis.

In the heuristic value that this part proposes, the D2D link that base station can realize being assigned to m bar same spectrum resources carries out redistribute resources, the channel information of the receiving terminal of the base station that base station utilization obtains and D2D link judges the disturbed condition on every block frequency spectrum resource, and then the quality judging for different D2D link performance, can be good at like this utilizing Given information to carry out scheduling of resource, do not need extra computing cost, algorithm specifically describes as follows:

1) as previously mentioned, base station can obtain the channel information of all channels be attached thereto, the channel information between the receiving terminal of the D2D link that the base station of acquisition and s bar are disturbed by base station mutually i ∈ 1 ..., n}, j ∈ 1 ..., s} sorts from small to large, namely the channel coefficient matrix of a s × n can be obtained like this:

$G_{\mathrm{BD}}={\left[\begin{array}{c}\underset{i}{\mathrm{sort}}\left({{\left|h_{B_i{D}_1}\right|}^{2}L}_{{\mathrm{BD}}_1}^{-\mathrm{\α}}\right)\\ \underset{i}{\mathrm{sort}}\left({{\left|h_{B_i{D}_2}\right|}^{2}L}_{{\mathrm{BD}}_2}^{-\mathrm{\α}}\right)\\ .\\ .\\ .\\ \underset{i}{\mathrm{sort}}\left({{\left|h_{B_i{D}_s}\right|}^{2}L}_{{\mathrm{BD}}_s}^{-\mathrm{\α}}\right)\end{array}\right]}_{s\×n}---\left(22\right)$

Wherein, 1≤u≤s, namely u article of D2D link assignment has arrived i ^*resource and be subject to other and be assigned to i ^*the interference of the D2D link of resource.In matrix (23), to be base station arrange from small to large to the channel coefficients of D2D link receiving terminal in each provisional capital.Analysis spectrum redistribute resources problem is carried out below, definition [j, k] with u article of D2D link, v ∈ 1 ..., G in n} representing matrix _bDthe frequency spectrum resource that middle jth row kth row are corresponding, such as [u, 1] represents frequency spectrum resource i ^*.

2) owing to being subject to the interference of other D2D links, u article D2D link can not use [u, 1] resource, now for it distributes frequency spectrum resource [u, 2], and judge to use frequency spectrum resource [u, 2] restrictive condition (18) whether is met time, if meet this restrictive condition, enter 3), if do not meet restrictive condition, can [u be learnt according to formula (5), 3], [u, n] all can not meet restrictive condition (18), now terminates to distribute the frequency spectrum resource of this D2D link.

3) when frequency spectrum resource [u, 2] meets restrictive condition (18), base station needs to do two judgements: one is judge whether frequency spectrum resource [u, 2] is elected to be optimum frequency spectrum resource by the D2D link outside m bar according to channel coefficients is minimum; Two be judge frequency spectrum resource [u, 2] whether with [j, 2], j ∈ 1 ..., s}, j ≠ u is identical frequency spectrum resource, if frequency spectrum resource [u, 2] is not elected to be optimum resource and resource [u by the D2D link outside m bar, 2] not [j, 2], j ∈ { 1,, s}, j ≠ u resource, then frequency spectrum resource [u, 2] distributes to u article of D2D link.

4) if frequency spectrum resource [u, 2] optimum resource is elected to be by the D2D link outside m bar according to channel coefficients is minimum, then frequency spectrum resource [u, 2] u article of D2D link can not be distributed to, now base station judges frequency spectrum resource [u, 3], 2 are repeated) 3), until give u article of D2D link assignment to the resource meeting restrictive condition.If frequency spectrum resource [u, 2] is not elected to be optimum resource but frequency spectrum resource [u, 2] is [j, 2] by the D2D link outside m bar according to channel coefficients is minimum, j ∈ 1 ..., s}, j ≠ u, then now base station according to channel coefficients with magnitude relationship carry out Resourse Distribute: if then distribute frequency spectrum resource [u, 2] to u article of D2D link; If then do not distribute frequency spectrum resource [u, 2] to u article of D2D link, now base station judges frequency spectrum resource [u, 3], repeats 2) 3), until give u article of D2D link assignment to the resource meeting restrictive condition.

The present invention is directed to the scene of the multipair D2D telex network existed in cellular network, propose the method for the multiplexing phone user's down frequency spectrum resources of a kind of simple D2D user, D2D user is communicated by share spectrum resources.The inventive method utilizes the interference-limited regional coordination of phone user to reduce D2D user to the interference of phone user, carry out Resourse Distribute by what optimize the be re-used cellular link of frequency spectrum resource and D2D link with capacity, finally the D2D link being assigned to same spectrum resources is carried out to the reallocation of frequency spectrum resource.This method effectively can reduce the mutual interference between cellular link and D2D link, elevator system spectrum efficiency.Meanwhile, when this method increases for the quantity right as D2D user in cellular cell, algorithm complex is relatively low.

Fig. 2, Fig. 3, Fig. 4 give the performance of different resource allocative decision under different index parameters.Can find out that resource allocation methods of the present invention effectively can reduce the mutual interference between D2D link and cellular link from Fig. 5 (a), Fig. 5 (b).

Claims (8)

1. introduce a down frequency spectrum resources distribution method for D2D technology in cellular network, it is characterized in that, the concrete steps of this resource allocation methods are:

(1) D2D communication link is set up, assuming that: D2D link transmissions end D _tconstant transmitting power P is adopted in the process of communication _dtransmission information, and the channel between D2D user and phone user only considers large scale fading effect; If distance D _twhen the frequency spectrum resource of nearer phone user is multiplexing by D2D link, user D _tto the interference I of phone user _dCexceed phone user and can bear interference threshold value, as phone user and D _tdistance when exceeding certain length value, the interference I that phone user receives _dClower than interference threshold value;

(2) at descending time slot, the frequency spectrum resource of the multiplexing cellular link of D2D link, D2D user produces interference to phone user, utilizes the interference-limited region of phone user to reduce D2D user to the interference of phone user, thus ensures the proper communication of phone user;

(3) with cellular link and D2D link sum maximum capacity for target distributes frequency spectrum resource to D2D communication link;

(4) when different D2D link assignment is to identical frequency spectrum resource, the D2D link being assigned to same spectrum resources is carried out to the reallocation of frequency spectrum resource.

2. introduce the down frequency spectrum resources distribution method of D2D technology as claimed in claim 1 in a kind of cellular network, it is characterized in that, in described step (2), base station utilizes the transmitting power of D2D user and path loss model to calculate the interference-limited region of phone user, the frequency spectrum resource of the phone user in interference-limited region can not be multiplexing by D2D user, and the center of circle, described interference-limited region is D2D transmitting terminal D _t, radius is: wherein, P _dfor the transmitting power that D2D user is constant, c is path loss coefficient, N ₀for noise power, δ _cfor the threshold value of the interference-to-noise ratio that phone user receives.

3. introduce the frequency spectrum resource allocation method of D2D technology as claimed in claim 1 in a kind of cellular network, it is characterized in that, the concrete steps of described step (3) are: first, under downstream spectrum multiplexer mode, calculate the letter drying ratio of phone user and D2D user with then according to the dry ratio of the letter of correspondence, the capacity of respective link is calculated with finally carry out Resourse Distribute with the maximum target that turns to of capacity sum of cellular link and D2D link, wherein, maximize with the formula with the capacity sum of cellular link and D2D link represent, must meet simultaneously cellular link and D2D link can proper communication and D2D link at most can only the frequency spectrum resource of a multiplexing cellular link.

4. introduce the down frequency spectrum resources distribution method of D2D technology in a kind of cellular network as claimed in claim 3, it is characterized in that, maximizing to the capacity sum of cellular link and D2D link the method solved is:

First by formula $\max \underset{i=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\α}}_i(r_C^i+r_{D2D}^i)$ Be reduced to: $\min \underset{\underset{{i\≠R}_{{\mathrm{\δ}}_c}}{i=1}}{\overset{n}{\mathrm{\Σ}}}{{\mathrm{\α}}_i\left|h_{B_{i}D}\right|}^2{P}_B{L}_{\mathrm{BD}}^{-\mathrm{\α}},$ Wherein, α _ifor the resource of the multiplexing phone user of D2D user, h _biDfor the channel coefficients between base station and D2D user, P _bfor the transmitted power of base station, L _bDfor the link range of base station and D2D user, α is path loss index, for the frequency spectrum resource that the phone user in interference-limited region takies;

The result of Resourse Distribute namely solving result represent as follows:

wherein, i ^*for optimum resource index;

Because base station can obtain the channel information of all channels be attached thereto, therefore, base station obtains channel coefficients during the multiplexing different spectral resource of D2D link, distributes to D2D link with the frequency spectrum resource that spectral channel coefficient is minimum.

5. introduce the down frequency spectrum resources distribution method of D2D technology as claimed in claim 1 in a kind of cellular network, it is characterized in that, the concrete steps of step (4) are: when occurring that m bar D2D link assignment is to same resource i ^*situation time, adopt following methods to distribute again frequency spectrum resource, ensure that m bar D2D link can proper communication, wherein, m>=2;

(4.1) due to m ?the non-interfering D2D link of s bar can continue to use frequency spectrum resource i ^*, therefore, then the process of sub-distribution represents with following formula:

$\underset{{\mathrm{\β}}_{i,j}}{\max }\underset{i=1}{\overset{n}{\mathrm{\Σ}}}\underset{j=1}{\overset{m}{\mathrm{\Σ}}}{\mathrm{\β}}_{i,j}{\log }_2(1+{\mathrm{\γ}}_{{D2D}_j}^i);$

Wherein, _jrepresent the sequence number of D2D link, β _i,j∈ { 0,1}, β _i,j=1 represents that sequence number is _jthe multiplexing label of D2D link be _ifrequency spectrum resource;

Need to meet base station is can proper communication after the D2D link reallocation frequency spectrum resource that mutually disturbs of S bar simultaneously, and a multiplexing at most cellular link resource of D2D link, ensure that the D2D link of interference mutually does not use identical frequency spectrum resource simultaneously;

(4.2) to the equations in step (4.1), the result of frequency spectrum resource reallocation is obtained.

6. in a kind of cellular network as claimed in claim 5, introduce the down frequency spectrum resources distribution method of D2D technology, it is characterized in that, the method for solving of step (4.2) is: redistribute resources is carried out to the D2D link that m bar is assigned to same spectrum resources in base station, the channel information of the receiving terminal of the base station that base station utilization obtains and D2D link judges the disturbed condition on every block frequency spectrum resource, and then the quality judging for different D2D link performance, utilize Given information to carry out scheduling of resource.

7. introduce the down frequency spectrum resources distribution method of D2D technology in a kind of cellular network as described in claim 5 or 6, it is characterized in that, the concrete method for solving of step (4.2) is:

(4.2.1) channel information between the receiving terminal of D2D link that the base station of acquisition and s bar are disturbed mutually of base station i ∈ 1 ..., n}, j ∈ 1 ..., s} sorts from small to large, namely obtain the channel coefficient matrix of a s × n, to be base station arrange from small to large to the channel coefficients of D2D link receiving terminal for each provisional capital of this matrix;

(4.2.2) suppose that u article of D2D link assignment has arrived i ^*frequency spectrum resource and be subject to other and be assigned to i ^*the interference of the D2D link of frequency spectrum resource, wherein, i ^*[u in representing matrix, 1] frequency spectrum resource, then u article of D2D link can not use [u, 1] resource, be now its preassignment frequency spectrum resource [u, 2], then judge whether this frequency spectrum resource [u, 2] can ensure that base station is can proper communication after the D2D link reallocation frequency spectrum resource that mutually disturbs of S bar, if met, enter step (4.2.3), if do not met, terminate frequency spectrum resource and distribute;

(4.2.3) judge: whether (1) frequency spectrum resource [u, 2] is elected to be optimum frequency spectrum resource by the D2D link outside m bar according to channel coefficients is minimum; (2) judge frequency spectrum resource [u, 2] whether with [j, 2], j ∈ 1 ..., s}, j ≠ u is identical frequency spectrum resource; If all whether condition (1) and condition (2), then by frequency spectrum resource [u, 2] u article of D2D link is distributed to, if condition (1) is yes, then base station judges frequency spectrum resource, repeat step (4.2.1) to step (4.2.3), until give u article of D2D link assignment to the frequency spectrum resource meeting restrictive condition; If condition (1) is not for no and condition (2) is yes, then, Resourse Distribute is carried out according to the magnitude relationship of channel coefficients in base station.

8. introduce the down frequency spectrum resources distribution method of D2D technology in a kind of cellular network as claimed in claim 7, it is characterized in that, in step (4.2.3), the method that Resourse Distribute is carried out according to the magnitude relationship of channel coefficients in base station is: if then base station assigns frequency spectrum resource [u, 2] is to u article of D2D link; If base station judges frequency spectrum resource [u, 3], repeats step (4.2.1) to step (4.2.3), until give u article of D2D link assignment to the resource meeting restrictive condition.