CN103873146B - Resource regulating method in indoor distributed visible light communication system - Google Patents

Abstract

The invention belongs to visible light communication field, provide the resource regulating method in a kind of indoor distributed visible light communication system, at the multiple equidistant LED access point of indoor layout, the signal transmission power setting each access point is identical, and single access point can only send signal to a user at most in single point in time, all access points control by a central control node, and the matrix then by forming the channel information between each time slot access point and user carries out computing to be dispatched multi-user.The present invention has avoided the interference between user, obtains under indoor distributed visible light communication system the dispatching method that total capacity is large, fairness good, hardware implementing is simple, computation complexity is low, effectively can embody the high feature of this system user reusability.

Description

Resource regulating method in indoor distributed visible light communication system

Technical field

The present invention relates to visible light communication field, the resource regulating method in a kind of indoor distributed visible light communication system.

Background technology

Visible light communication technology becomes the focus of communications field research in recent years gradually.It has the wide-band spectrum resources independent of radio spectrum, and without electromagnetic interference and radiation, green safety, is easy to cut off signal, the advantages such as good confidentiality.Because visible light communication system has the function that can realize room lighting and radio communication simultaneously, distributed system can be formed at the multiple LED access point of indoor layout.

Because the characteristic of channel of visible light communication and locus are closely related, the multiple access of high reusability can be realized in indoor visible light communication system.Under multi-user scene in a distributed system, need efficient dispatching algorithm to carry out the Resource Distribution and Schedule to multi-user, realize multi-user and jointly access, reach high power capacity as far as possible and meet certain fairness.

Summary of the invention

The present invention is directed to above-mentioned prior art Problems existing to make improvements, namely the technical problem to be solved in the present invention is to provide the resource regulating method in a kind of indoor distributed visible light communication system, resource regulating method in this indoor distributed visible light communication system provides solution for the Resource Distribution and Schedule of indoor distributed visible light communication system under multi-user's situation, increases power system capacity and meet fair principle under lower complexity.

In order to solve the problems of the technologies described above, the invention provides following technical scheme:

Resource regulating method in a kind of indoor distributed visible light communication system, at the multiple equidistant LED access point of indoor layout, the signal transmission power setting each access point is identical, and single access point can only send signal to a user at most in single point in time, all access points control by a central control node, and the matrix then by forming the channel information between each time slot access point and user carries out computing to be dispatched multi-user.

Described calculation step is:

Setting N is the number of LED access point, and K is number of users, and access point place plane is h to the vertical range of user place plane, and the spacing of access point and access point is d,

S1. at each time slot, described central control node obtains the channel information between each access point and user sent to by reverse link and forms channel matrix H _{(K × N)};

S2. the connection matrix C between user and access point is produced by channel matrix _{(K × N)};

S3. adjacency matrix N between user is produced by connection matrix again _{(K × K)};

S4. according to adjacency matrix N _{(K × K)}producing undirectedly has weight map model, and undirectedly has weight map model to be called interference figure by described, and the vertex set of figure is user's set, and when two users can receive the signal of a common access point simultaneously, the Jian You limit, summit of their correspondences connects;

S5. the weight on each summit is calculated by the adjoint point number of this point of equitable proportion Summing Factor and produces;

S6. the user that weight selection is maximum from vertex set, is added user's set that this time slot is scheduled, is removed this user and its adjoint point user from candidate collection; And so forth, until do not have user to remain in candidate collection.

At each time slot, described central control node obtains from each access point the channel information that reverse link feedback returns, and produces channel matrix H _{(K × N)}, element h _ijfor from a jth access point to the channel gain of i-th user.

At each time slot, described central control node is according to channel matrix H _{(K × N)}, produce connection matrix C _{(K × N)}, wherein each element definition is

$c_{ij}=\left\{\begin{array}{cc}1,& h_{ij}\≠0,\\ 0,& h_{ij}=0.\end{array}\right..$

At each time slot, described central control node is according to connection matrix C _{(K × N)}, produce adjacency matrix N _{(K × K)}, wherein each element definition is

$n_{ij}=\{\begin{array}{cc}\max \{c_{ik}\·c_{jk}\},k=1,\mathrm{...},N,& i\≠j,\\ 0,& i=j.\end{array}.$

At each time slot, described central control node is according to adjacency matrix N _{(K × K)}, producing undirectedly has weight map G ^(w)(V, E), is called interference figure; The vertex set V (G) of described interference figure is the user's set in scene, and the generation principle on limit collection E (G) is: if n _ij=1, there is a limit to be connected between the summit that user i with j is corresponding, otherwise be not connected.

At each time slot, described central control node calculates interference figure G ^(w)the weight on each summit in (V, E), user i at the weight calculation formula of time slot k is

$w_{i,k}=\frac{p_{i,k}}{d\left(v_i\right)+1}$

Wherein p _{i, k}for the equitable proportion factor of user, computational methods are

$p_{i,k}=\frac{r_{i,k}}{\stackrel{\‾}{r_{i,k}}}$

Wherein r _{i, k}for user i is at the achievable rate of time slot k, for it is at front T _caverage throughput in individual time slot, computational methods are

D (v _i) be summit adjoint point number in the drawings corresponding to user i.

At each time slot, described central control node selects this time slot by serviced user from V (G), and its process is:

A1. candidate collection is V (G), and the set selected is empty set;

A2. from candidate collection, selecting the point that weight is maximum, add and select set, a little deleting selecting from candidate collection with its adjoint point;

A3. repeat steps A 2 until candidate collection is empty set, set of selecting now corresponds to and serviced user is gathered.

At each time slot, for each user be selected, corresponding c _ijall access points of=1 launch identical signal; If there is remaining idle access point, can only be received, can not produce interference, also transmit to relative users to other user owing to transmitting by a user, described central control node to complete in this time slot access point to the distribution of multi-user.

The performance of this dispatching method affects by the range of receiving of receiver.When receiver receiving angle (FOV) close to time, this dispatching method can obtain optimum, obtains larger user's total capacity and good fairness.

Resource regulating method in indoor distributed visible light communication system provided by the invention achieves the scheduling in indoor visible light communication under multi-access point multi-user sight, and its beneficial effect is:

1, avoided the interference between multi-user in dispatching method, the receiving demodulation of receiver has been operated easier, be easy to Receiver Design and realize;

2, for each user takes full advantage of available multiple access point resources, realize transmit diversity, enhance received signal strength and user capacity;

3, the user that scheduling is as far as possible many is simultaneously serviced, takes full advantage of high reusability characteristic potential in indoor visible light communication system, improves the total capacity of system;

4, employ proportional fairness principle, ensure that fairness between the user under multi-subscriber dispatching.

Accompanying drawing explanation

Accompanying drawing is used to provide a further understanding of the present invention, and forms a part for specification, together with embodiments of the present invention for explaining the present invention, is not construed as limiting the invention.In the accompanying drawings:

Fig. 1 is the inventive method logic diagram;

Fig. 2 be preferred embodiment of the present invention indoor distributed visible light communication system in access point and user layout schematic diagram;

Fig. 3 is the interference figure model schematic obtained under Fig. 2 layout;

Fig. 4 is received signal to noise ratio simulation result under preferred embodiment of the present invention;

Fig. 5 is scheduling performance under preferred embodiment of the present invention and other scheme comparative result for total capacity;

The comparative result of total capacity when Fig. 6 is different receivers receiving angle under preferred embodiment of the present invention;

The comparative result of business fair index when Fig. 7 is different receivers receiving angle under preferred embodiment of the present invention.

Embodiment

As shown in figs. 1-7, the present invention discloses the resource regulating method in a kind of indoor distributed visible light communication system, is arranged on the visible light communication system in the larger room of area for one, arranges multiple LED access point, dispatches for multi-user's situation.

As, set N number of LED access point and equidistantly settle on the ceiling, wherein the spacing of each access point is d; K user is randomly dispersed in room, and the ceiling at access point place is h to the vertical range of user place plane.The signal transmission power of each access point is identical, and single access point can only be at most user's service in a time slot.All access points control by a central control node, to realize scheduling operation simultaneously.

For under this scene, the step of the dispatching method that the present invention proposes comprises:

1, at each time slot, in system, all access points receive self to can the channel information of service-user by reverse link from user, then send to central control node.Central control node, according to the channel information obtained from each access point, produces channel matrix H _{(K × N)}.Channel matrix H _{(K × N)}in element h _ijfor from a jth access point to the channel gain of i-th user.

2, channel matrix H is created _{(K × N)}after, central control node is again according to channel matrix H _{(K × N)}produce connection matrix C _{(K × N)}.Connection matrix C _{(K × N)}in each element by channel matrix H _{(K × N)}in element correspondence produce, be specially

$c_{ij}=\left\{\begin{array}{cc}1,& h_{ij}\≠0,\\ 0,& h_{ij}=0.\end{array}\right.$

If c _ij=1, illustrate that user i can receive the signal of a jth access point.Because received signal to noise ratio in indoor visible light communication system is general higher, namely this show there is an active link between user i and access point j.

3, connection matrix C is produced _{(K × N)}after, central control node is according to connection matrix C _{(K × N)}, produce adjacency matrix N _{(K × K)}, wherein each element is

$n_{ij}=\left\{\begin{array}{cc}\max \{c_{ik}\·c_{jk}\},k=1,\mathrm{...},N,& i\≠j,\\ 0,& i=j.\end{array}\right.$

This step shows, if i, j two users can be connected with at least one access point simultaneously, then and corresponding n _ij=1, think that these two users are adjacent.

4, adjacency matrix N is produced _{(K × K)}after, central control node is according to adjacency matrix N _{(K × K)}, producing one undirectedly has weight map G ^(w)(V, E), is called interference figure model.The vertex set V (G) of interference figure is the user's set in scene, and namely each user corresponds to a summit in figure; The generation principle on limit collection E (G) is: if n _ij=1, then have a limit to connect between the summit that user i and j is corresponding, otherwise these two summits are not connected.A limit is only had at most to be connected between any two summits.Interference figure G ^(w)(V, E) reflects the disturbed condition in scene between user.If the user of two vertex correspondence be connected by limit in the drawings receives simultaneously, then a user is wherein had at least to be interfered.

5, the undirected interference figure G having weight is produced ^(w)after (V, E), the weight on each summit in central control node calculating chart.Summit corresponding to user i is at the weight w of time slot k _{i, k}computational methods be

$w_{i,k}=\frac{p_{i,k}}{d\left(v_i\right)+1}$

Wherein d (v _i) be summit adjoint point number in the drawings corresponding to user i, p _{i, k}for user i is in the equitable proportion factor of time slot k, computational methods are

$p_{i,k}=\frac{r_{i,k}}{\stackrel{\‾}{r_{i,k}}}$

Wherein r _{i, k}for user i is at the achievable rate of time slot k, for it is at front T _caverage throughput in individual time slot, computational methods are

6, after determining the weight on each summit in interference figure, central control node selects this time slot by serviced user from V (G), and its process is: first setting candidate collection is V (G), and the set selected is empty set.From candidate collection, select the point that weight is maximum subsequently, added and select set, this point and its adjoint point are deleted from candidate collection.Repeat this step until candidate collection is empty set.Set of selecting now corresponds to and serviced user is gathered.

7, for the single user be selected, its corresponding c _ijall access points of=1 launch identical signal to it.In addition, if there is remaining idle access point, transmitting of idle access point can only be received by a user, can not produce interference to other user.So far central control node to complete in this time slot access point sharing out the work to user in system.、

Now the present invention is made in conjunction with the embodiments and further illustrating:

Shown in figure 2, consider in a foursquare room, be evenly arranged 8 × 8 access points, access point represents by "○" in fig. 2, and the spacing between neighboring access point is identical.In this room, be sprinkled into 10 users at random, user represents with " " in fig. 2 simultaneously.When in the coverage that user is in a certain access point, be connected with dotted line between user and access point, represent c corresponding in connection matrix C _ij=1.

Fig. 3 demonstrates the interference figure G produced according to the access point in Fig. 2 and user layout ^(w)(V, E).With the summit that the user that " " represents is in figure, n corresponding in adjacency matrix _ijlimit is had to connect between the user of=1, indicated by the solid line in figure 3.The example of the user be scheduled in the time slot utilizing method of the present invention to obtain with the user that "○" is irised out in Fig. 3, they between two mutually between there is not interference, can work simultaneously.

Accompanying drawing 4-6 gives the Performance Simulation Results utilizing dispatching method of the present invention.

Simulated example:

Be similar to Fig. 2, set 8 × 8 access points and be uniformly distributed at equal intervals, the spacing of neighboring access point is 2 meters.The ceiling at access point place is 2.2 meters to the vertical range of the horizontal plane at user place.Fig. 4 gives the simulation result of received signal to noise ratio under this scene.

In scene, 1 to 16 user is sprinkled at random in emulation.In each number of users situation, be repeatedly sprinkled into 5000 times at random, each statistics 50 time slots, carry out statistics and calculating mean value to result, obtain the simulation result of Fig. 4-6.

User's total capacity that Fig. 5 compares the dispatching method based on interference figure that the present invention provides and other two kinds of methods compares.Two kinds of methods being used for comparing are respectively: (1) each access point distributes to the user that in its coverage, channel gain is maximum; (2) utilize existing conflict graph model analysis to disturb, access point is distributed.Can find out, the user's total capacity obtained based on the dispatching method of interference figure model is significantly improved compared to other method, this is because method of the present invention takes full advantage of the transmit diversity of multi-access point and the high reusability characteristic of indoor visible light communication system on the basis of avoiding inter-user interference, make the number of users be scheduled try one's best many, and the capacity of each user is as far as possible large.

Fig. 6 and Fig. 7 gives and utilizes dispatching method of the present invention, at the simulation result of different receiver receiving angle (FOV) value dispatching performances.Wherein Fig. 6 investigates under different receiver range of receiving sizes, user's total capacity that scheduling obtains.Fig. 7 investigates under different receiver range of receiving sizes, the fair index of the business that scheduling obtains.The fair index of business is less, and the fairness of scheduling is better.Can find out, when the receiving angle of receiver is 30 °, can obtain larger user's total capacity and better fairness, dispatching effect is best.The performance of dispatching method of the present invention affects by the range of receiving of receiver, and preferably receiver receiving angle is about best scheduling result can be obtained near this scope.Excessive receiving angle to make between potential user interference become many, makes the number of users that can be scheduled simultaneously little.Too small receiving angle limits the obtainable access point resource of each user.

To sum up, the inventive method has avoided the interference between multi-user, the receiving demodulation of receiver is operated easier, is easy to Receiver Design and realizes; For each user takes full advantage of available multiple access point resources, realize transmit diversity, enhance received signal strength and user capacity; Dispatch as far as possible many users simultaneously serviced, take full advantage of high reusability characteristic potential in indoor visible light communication system, improve the total capacity of system; Employ proportional fairness principle, ensure that fairness between the user under multi-subscriber dispatching.

The foregoing is only the preferred embodiments of the present invention, be not limited to the present invention, although with reference to previous embodiment to invention has been detailed description, for a person skilled in the art, it still can be modified to the technical scheme described in foregoing embodiments, or carries out equivalent replacement to wherein portion of techniques feature.Within the spirit and principles in the present invention all, any amendment done, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (9)

1. the resource regulating method in an indoor distributed visible light communication system, it is characterized in that: at the multiple equidistant LED access point of indoor layout, the signal transmission power setting each access point is identical, and single access point can only send signal to a user at most in single point in time, all access points control by a central control node, then by carrying out computing to the matrix that the channel information between each time slot access point and user is formed, thus multi-user is dispatched; Described calculation step is:

Setting N is the number of LED access point, and K is number of users, and access point place plane is h to the vertical range of user place plane, and the spacing of access point and access point is d,

S1. at each time slot, described central control node obtains the channel information between each access point and user sent to by reverse link and forms channel matrix H _{(K × N)};

S2. the connection matrix C between user and access point is produced by channel matrix _{(K × N)};

S3. adjacency matrix N between user is produced by connection matrix again _{(K × K)};

S4. according to adjacency matrix N _{(K × K)}producing undirectedly has weight map model, and undirectedly has weight map model to be called interference figure by described, and the vertex set of figure is user's set, and when two users can receive the signal of a common access point simultaneously, the Jian You limit, summit of their correspondences connects;

S5. the weight on each summit is calculated by the adjoint point number of this point of equitable proportion Summing Factor and produces;

S6. the user that weight selection is maximum from vertex set, is added user's set that this time slot is scheduled, is removed this user and its adjoint point user from candidate collection; And so forth, until do not have user to remain in candidate collection.

2. the resource regulating method in indoor distributed visible light communication system according to claim 1, is characterized in that: at each time slot, and described central control node obtains from each access point the channel information that reverse link feedback returns, and produces channel matrix H _{(K × N)}, element h _ijfor from a jth access point to the channel gain of i-th user.

3. the resource regulating method in indoor distributed visible light communication system according to claim 2, it is characterized in that: at each time slot, described central control node is according to channel matrix H _{(K × N)}, produce connection matrix C _{(K × N)}, wherein each element definition is

4. the resource regulating method in indoor distributed visible light communication system according to claim 3, it is characterized in that: at each time slot, described central control node is according to connection matrix C _{(K × N)}, produce adjacency matrix N _{(K × K)}, wherein each element definition is

5. the resource regulating method in indoor distributed visible light communication system according to claim 4, it is characterized in that: at each time slot, described central control node is according to adjacency matrix N _{(K × K)}, producing undirectedly has weight map G ^(w)(V, E), is called interference figure; In described interference figure, each user corresponds to a summit in figure, and vertex set V (G) is the user's set in scene, and the generation principle on limit collection E (G) is: if n _ij=1, there is a limit to be connected between the summit that user i with j is corresponding, otherwise be not connected.

6. the resource regulating method in indoor distributed visible light communication system according to claim 5, is characterized in that: at each time slot, and described central control node calculates interference figure G ^(w)the weight on each summit in (K, E), user i at the weight calculation formula of time slot k is

Wherein p _{i, k}for the equitable proportion factor of user, computational methods are

Wherein r _{i, k}for user i is at the achievable rate of time slot k, for it is at front T _caverage throughput in individual time slot, computational methods are

D (v _i) be summit adjoint point number in the drawings corresponding to user i.

7. the resource regulating method in the indoor distributed visible light communication system stated according to claim 6, it is characterized in that: at each time slot, described central control node selects this time slot by serviced user from V (G), and its process is:

A1. candidate collection is V (G), and the set selected is empty set;

A2. from candidate collection V (G), selecting the maximum point of weight, add and select set, a little deleting selecting from candidate collection with its adjoint point;

A3. repeat steps A 2 until candidate collection V (G) is empty set, set of selecting now corresponds to and serviced user is gathered.

8. the resource regulating method in indoor distributed visible light communication system according to claim 7, is characterized in that: at each time slot, for each user be selected, and corresponding c _ijall access points of=1 launch identical signal.

9. the resource regulating method in indoor distributed visible light communication system according to claim 1, is characterized in that: the receiving angle choosing receiver is