CN115942499B - Multi-user scheduling method and scheduling device based on visible light communication - Google Patents
Multi-user scheduling method and scheduling device based on visible light communication Download PDFInfo
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Abstract
The utility model provides a multiuser scheduling method and scheduling device based on visible light communication, a plurality of optical access points are distributed in the area scope, and the multiuser scheduling method comprises the following steps: when the available light access points of the target user equipment are overlapped with the available light access points of other user equipment, obtaining a weighted evaluation value of the target user equipment according to the data transmission rate between the target user equipment and all the available light access points; obtaining weighted evaluation values of other user equipment according to the data transmission rates between the other user equipment and all the available optical access points; when the weighted evaluation value of the target user equipment is larger than that of the other user equipment, allowing the target user equipment to communicate with all available optical access points of the target user equipment, and carrying out joint transmission on all the available optical access points; other user devices are prohibited from communicating with their available optical access points. The method and the device can reduce the problems in the prior art and improve the fairness among users on the premise of eliminating the inter-cell interference.
Description
Technical Field
The present invention relates to the field of communications, and in particular, to a method and apparatus for scheduling multiple users based on visible light communications.
Background
Visible light has abundant frequency spectrum resources, can provide higher bandwidth, is used without authorization, uses a commercial Light Emitting Diode (LED) transmitter for visible light communication, directly transmits light signals in air, has the advantages of high transmission speed, wide coverage, high confidentiality, low cost and power consumption and the like, and simultaneously meets the requirements of energy-saving illumination. Visible light communication can be used for indoor short-distance communication, internet of vehicles communication and the like in 5G.
The existing technology of the fixed-shape regular cells with different frequency division multiplexing modes and the combined cells adopting the advanced transmission scheme with the cells as centers solves the problem of inter-cell interference of the line-of-sight transmission signals of a plurality of access points which are simultaneously received by users in the overlapping coverage areas of the cells, but still has the problems of frequent horizontal switching and interruption, low frequency spectrum utilization rate, high algorithm complexity and the like, and does not consider the flow requirement and fairness among multiple users.
Therefore, there is a need for a multi-user scheduling method based on visible light communication, which reduces the problems in the prior art and improves the fairness among users on the premise of eliminating inter-cell interference.
Disclosure of Invention
An object of the embodiments herein is to provide a multi-user scheduling method and scheduling apparatus based on visible light communication, so as to reduce problems in the prior art and improve fairness among users on the premise of eliminating inter-cell interference.
In order to achieve the above object, in one aspect, an embodiment herein provides a multi-user scheduling method based on visible light communication, in which a plurality of optical access points are distributed in a region, the multi-user scheduling method includes:
when the current scheduling time comes, taking the optical access points with the incidence angles to the user equipment smaller than the field angle of the user equipment in all the optical access points as the available optical access points of the user equipment;
when the available light access points of the target user equipment are overlapped with the available light access points of other user equipment, obtaining a weighted evaluation value of the target user equipment according to the data transmission rate between the target user equipment and all the available light access points of the target user equipment; obtaining weighted evaluation values of the other user equipment according to the data transmission rates between the other user equipment and all the available optical access points;
when the weighted evaluation value of the target user equipment is larger than that of the other user equipment, allowing the target user equipment to communicate with all available optical access points thereof, wherein all the available optical access points perform joint transmission; the other user device is prohibited from communicating with its available optical access point.
Preferably, the method for determining the data transmission rate between the target user equipment and the available optical access point thereof comprises the following steps:
obtaining a total direct current attenuation value of an optical channel of the available optical access point according to the incident angle of the available optical access point to target user equipment and the field angle of the target user equipment;
obtaining the signal-to-interference-plus-noise ratio of the available optical access point according to the receiving power of the target user equipment and the total direct current attenuation value of the optical channel;
and obtaining the data transmission rate between the target user equipment and the available optical access point according to the signal to interference plus noise ratio of the available optical access point.
Preferably, the obtaining the total dc attenuation value of the optical channel of the available optical access point according to the incident angle of the available optical access point to the target user device and the view angle of the target user device further includes:
the total dc attenuation value of the optical channels of the optical access point is calculated by the following formula:
wherein ,
，/>
half-power angle for available light access point, +.>
For the full power angle of the available optical access point, < >>
The gains of the optical filter and the optical concentrator respectively,
，/>
n is the reflection index of the optical concentrator, < - >
For the angle of incidence of the available optical access point to the target user equipment +.>
For the angle of view of the target user device, r is the distance from the available optical access point to the target user device, D PA Is the physical area of the available optical access point.
Preferably, the obtaining the signal to interference plus noise ratio of the available optical access point according to the received power of the target user equipment and the total dc attenuation value of the optical channel further includes:
the signal to interference plus noise ratio of an available optical access point is calculated by the following formula:
wherein 
G (j) is the j th row of the matrix G, H is the total DC attenuation value of the optical channels of the available optical access points, N is the total number of available optical access points, N 0 The noise power spectral density, B is the signal modulation bandwidth, gamma is the photoelectric conversion efficiency, +.>
，N shot Is the noise power spectral density of the optical signal, which is of the order of 10 -22 Q is electron charge, I a (P r,i ) For photocurrent at the target user equipment, S S S for an available optical access point belonging to a signal set I Is an available optical access point belonging to the interference set.
Preferably, the obtaining the data transmission rate between the target ue and the available optical access point according to the signal to interference plus noise ratio of the available optical access point further includes:
Obtaining a value range of the order of pulse amplitude modulation according to the signal-to-interference-plus-noise ratio, the signal error rate and the signal modulation mode of the available optical access node;
taking the maximum value in the value range as the order of pulse amplitude modulation;
and obtaining the data transmission rate between the target user equipment and the available optical access point according to the pulse amplitude modulation order and the signal modulation bandwidth.
Preferably, the obtaining the weighted evaluation value of the target ue according to the data transmission rate between the target ue and all the available optical access points thereof further includes:
obtaining an evaluation value of the target user equipment according to the data transmission rate between the target user equipment and all the available optical access points;
and obtaining the weighted evaluation value of the target user equipment according to the evaluation values of the other user equipment and the target user equipment.
Preferably, the obtaining the evaluation value of the target ue according to the data transmission rate between the target ue and all the available optical access points thereof further includes:
obtaining the total data transmission rate of the target user equipment according to the data transmission rates between the target user equipment and all the available optical access points;
According to the total data transmission rate of the target user equipment and the scheduling condition of the target user equipment in the last scheduling moment, calculating to obtain the long-term average throughput between the target user equipment and all the available optical access points thereof;
and calculating an evaluation value of the target equipment according to the total data transmission rate of the target user equipment and the long-term average throughput between the target user equipment and all the available optical access points thereof.
Preferably, the calculating, according to the total data transmission rate of the target ue and the scheduling situation of the target ue at the previous scheduling time, the long-term average throughput between the target ue and all the available optical access points thereof further includes:
the long-term average throughput between the target user device and all of its available optical access points is calculated by the following formula:
wherein ,TF For the duration between two adjacent scheduling moments, t is the current scheduling moment,
for the long-term average throughput between the target user equipment and all its available optical access points in the last scheduling instant +.>
The total data transmission rate of the target user equipment; if the target UE communicates with all available optical access points in the last scheduling time, the target UE is +. >
If the target UE does not communicate with its available optical access point in the last scheduling time, then +.>
。
Preferably, the obtaining the weighted evaluation value of the target ue according to the evaluation values of the other ue and the target ue further includes:
the number of the other user equipment is taken as the association number of the target user equipment;
and carrying out weighted calculation on the evaluation value of the target user equipment based on the association number of the target user equipment to obtain the weighted evaluation value of the target user equipment.
In another aspect, embodiments herein provide a multi-user scheduling apparatus based on visible light communication, in which a plurality of optical access points are distributed in a region, the multi-user scheduling apparatus including:
the available light access point determining module is used for taking light access points with incidence angles smaller than the field angle of the user equipment in all light access points as available light access points of the user equipment when the current scheduling time arrives;
the weighting priority value determining module is used for obtaining a weighting evaluation value of the target user equipment according to the data transmission rate between the target user equipment and all the available light access points of the target user equipment when the available light access points of the target user equipment are overlapped with the available light access points of other user equipment; obtaining weighted evaluation values of the other user equipment according to the data transmission rates between the other user equipment and all the available optical access points;
A scheduling module, configured to allow the target ue to communicate with all available optical access points thereof when the weighted priority value of the target ue is greater than that of the other ue, where the all available optical access points perform joint transmission; the other user device is prohibited from communicating with its available optical access point.
As can be seen from the technical solutions provided in the embodiments herein, a cell with a user as a center is formed by the method in the embodiments herein, and for any cell, there is one user equipment and at least one available optical access point in communication with the user equipment, if there are multiple available optical access points, the multiple available optical access points can perform joint transmission, so as to avoid signal interference. Any one optical access point in the cell belongs to the corresponding cell and is only communicated with the user equipment in the corresponding cell, so that the user experience can be improved. In addition, according to the weighted evaluation value of the user equipment, the overlapped available optical access points are determined to be in specific communication with which user equipment, and the fairness among multiple users is improved.
The foregoing and other objects, features and advantages will be apparent from the following more particular description of preferred embodiments, as illustrated in the accompanying drawings.
Drawings
In order to more clearly illustrate the embodiments herein or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described below, it being obvious that the drawings in the following description are only some embodiments herein and that other drawings may be obtained according to these drawings without inventive effort to a person skilled in the art.
Fig. 1 is a schematic flow chart of a multi-user scheduling method based on visible light communication according to an embodiment of the present disclosure;
fig. 2 is a flow chart illustrating a method for determining a data transmission rate between a target ue and an optical access point thereof according to an embodiment herein;
fig. 3 is a flow chart illustrating a data transmission rate to a target user device and an available optical access point according to a signal to interference plus noise ratio of the available optical access point provided by an embodiment herein;
fig. 4 is a schematic flow chart of obtaining a weighted evaluation value of a target ue according to an embodiment herein;
fig. 5 is a schematic flow chart of obtaining an evaluation value of a target user equipment according to an embodiment herein;
Fig. 6 is a schematic flow chart of obtaining a weighted evaluation value of a target user device according to evaluation values of other user devices and the target user device provided in the embodiments herein;
fig. 7 shows a schematic cell diagram of the rule of common frequency multiplexing provided by the embodiments herein;
fig. 8 shows a schematic diagram of a cell with a frequency reuse factor of 2 provided by embodiments herein;
fig. 9 shows a schematic diagram of two cells employing joint transmission combining as provided by embodiments herein;
fig. 10 shows a schematic diagram of a cell of two optical access points employing vector transmission combining as provided by embodiments herein;
fig. 11 illustrates a schematic diagram of a cell formed by a user-centric multi-user scheduling method based on visible light communication provided in an embodiment herein;
FIG. 12 illustrates a schematic comparison of average user throughput at different angles of view provided by embodiments herein;
FIG. 13 illustrates a schematic diagram of average user throughput for different occlusion probabilities at 120 degrees of field of view provided by embodiments herein;
FIG. 14 illustrates a schematic diagram of a Service Fairness Index (SFI) at a 120 degree field of view provided by embodiments herein;
fig. 15 is a schematic block diagram of a multi-user scheduling apparatus based on visible light communication according to an embodiment of the present disclosure;
Fig. 16 shows a schematic structural diagram of a computer device provided in embodiments herein.
Detailed Description
The following description of the embodiments of the present disclosure will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all embodiments of the disclosure. All other embodiments, based on the embodiments herein, which a person of ordinary skill in the art would obtain without undue burden, are within the scope of protection herein.
The existing technology of the fixed-shape regular cells with different frequency division multiplexing modes and the combined cells adopting the advanced transmission scheme with the cells as centers solves the problem of inter-cell interference of the line-of-sight transmission signals of a plurality of access points which are simultaneously received by users in the overlapping coverage areas of the cells, but still has the problems of frequent horizontal switching and interruption, low frequency spectrum utilization rate, high algorithm complexity and the like, and does not consider the flow requirement and fairness among multiple users.
To solve the above problems, embodiments herein provide a multi-user scheduling method based on visible light communication. Fig. 1 is a flow chart of a multi-user scheduling method based on visible light communication provided in the embodiments herein, the present disclosure provides the method operation steps described in the examples or the flow charts, but may include more or less operation steps based on conventional or non-inventive labor. The order of steps recited in the embodiments is merely one way of performing the order of steps and does not represent a unique order of execution. When a system or apparatus product in practice is executed, it may be executed sequentially or in parallel according to the method shown in the embodiments or the drawings.
It should be noted that the terms "first," "second," and the like in the description and claims herein and in the foregoing figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments described herein may be capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, apparatus, article, or device that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed or inherent to such process, method, article, or device.
Referring to fig. 1, embodiments herein provide a multi-user scheduling method based on visible light communication, in which a plurality of optical access points are distributed in a region, the multi-user scheduling method includes:
s101: when the current scheduling time comes, taking the optical access points with the incidence angles to the user equipment smaller than the field angle of the user equipment in all the optical access points as the available optical access points of the user equipment;
S102: when the available light access points of the target user equipment are overlapped with the available light access points of other user equipment, obtaining a weighted evaluation value of the target user equipment according to the data transmission rate between the target user equipment and all the available light access points of the target user equipment; obtaining weighted evaluation values of the other user equipment according to the data transmission rates between the other user equipment and all the available optical access points;
s103: when the weighted evaluation value of the target user equipment is larger than that of the other user equipment, allowing the target user equipment to communicate with all available optical access points thereof, wherein all the available optical access points perform joint transmission; the other user device is prohibited from communicating with its available optical access point.
The scheduling time arrives at intervals of set time, each time the scheduling time arrives, the optical access points with the incidence angle to the user equipment smaller than the view angle of the user equipment in all the optical access points are used as available optical access points of the user equipment, wherein the available optical access points are optical access points capable of communicating with the user equipment, and for the optical access points with the incidence angle to the user equipment larger than or equal to the view angle of the user equipment, the optical access points cannot communicate with the user equipment, namely the available optical access points of the user equipment.
When the available optical access point of the target user equipment coincides with the available optical access points of other user equipment, it is proved that the coincident optical access point is not only the available optical access point of the target user equipment, but also the available optical access point of other user equipment, and in the face of this situation, in order not to cause interference problems, it is necessary to determine with which user equipment the optical access point should communicate specifically.
When the available optical access point of the target user equipment does not overlap with the available optical access points of other user equipment, it is indicated that the target user equipment can form an independent cell, and the target user equipment is allowed to communicate with all the available optical access points thereof, and all the available optical access points perform joint transmission. At this time, although the target ue does not overlap with the available access points of other ues, it cannot be ensured that other ues do not overlap with the available access points of other ues, and therefore, it is not possible to determine the communication situation of other ues, and it is necessary to further use any other ue as the target ue, and determine whether the available access points of the target ue overlap with the available access points of other ues.
Specifically, the weighted evaluation values of the target ue and the other ues need to be obtained respectively, and it should be noted that there may be more than one other ue described herein, and one or more other ues may be used to determine which ue the coincident available optical access point a should communicate with.
And when the weighted evaluation value of the target user equipment is larger than that of other user equipment, allowing the target user equipment to communicate with all the available optical access points of the target user equipment, wherein the available optical access points corresponding to the target user equipment certainly comprise an available optical access point a overlapped with the other user equipment, and at the moment, all the available optical access points perform joint transmission, so that interference among the available optical access points is reduced. At this point, for an available optical access point a that is coincident with the presence of the target user device, other user devices are prohibited from communicating with their available optical access points. Of course, if the weighted evaluation value of the target ue is less than or equal to that of other ues, the overlapped available optical access point a communicates with other ues, and the target ue is prohibited from communicating with its available optical access point.
By forming a cell with a user as a center by the method in the embodiment, for any cell, there is one user equipment and at least one available optical access point in communication with the user equipment, and if there are multiple available optical access points, the multiple available optical access points can perform joint transmission, so as to avoid signal interference. Any one optical access point in the cell belongs to the corresponding cell and is only communicated with the user equipment in the corresponding cell, so that the user experience can be improved. In addition, according to the weighted evaluation value of the user equipment, the overlapped available optical access points are determined to be in specific communication with which user equipment, and the fairness among multiple users is improved.
In this embodiment, the light access point may be an LED lamp, and parameters of a specific LED lamp may be as shown in table 1 below:
TABLE 1
In this embodiment, referring to fig. 2, the method for determining the data transmission rate between the target ue and its available optical access point includes:
s201: obtaining a total direct current attenuation value of an optical channel of the available optical access point according to the incident angle of the available optical access point to target user equipment and the field angle of the target user equipment;
s202: obtaining the signal-to-interference-plus-noise ratio of the available optical access point according to the receiving power of the target user equipment and the total direct current attenuation value of the optical channel;
s203: and obtaining the data transmission rate between the target user equipment and the available optical access point according to the signal to interference plus noise ratio of the available optical access point.
Specifically, the obtaining the total dc attenuation value of the optical channel of the available optical access point according to the incident angle of the available optical access point to the target user equipment and the view angle of the target user equipment further includes:
the total dc attenuation value of the optical channels of the optical access point is calculated by the following formula:
wherein ,
，/>
Half-power angle for available light access point, +.>
For the full power angle of the available optical access point, < >>
Gain of optical filter and optical concentrator, respectively,/->
，
N is the reflection index of the optical concentrator, < ->
For the angle of incidence of the available optical access point to the target user equipment +.>
For the angle of view of the target user device, r is the distance from the available optical access point to the target user device, D PA Is the physical area of the available optical access point.
Further, the obtaining the signal to interference plus noise ratio of the available optical access point according to the received power of the target user equipment and the total dc attenuation value of the optical channel further includes:
the signal to interference plus noise ratio of an available optical access point is calculated by the following formula:
wherein 
G (j) is the j th row of the matrix G, H is the total DC attenuation value of the optical channels of the available optical access points, N is the total number of available optical access points, N 0 The noise power spectral density, B is the signal modulation bandwidth, gamma is the photoelectric conversion efficiency, +.>
，N shot Is the noise power spectral density of the optical signal, which is of the order of 10 -22 Q is electron charge, I a (P r,i ) For photocurrent at the target user equipment, S S S for an available optical access point belonging to a signal set I For an available optical access point belonging to the interference set, reference is made to fig. 7, where { a } is the signal set, { B, C, D } is the interference set.
In this embodiment, referring to fig. 3, the obtaining the data transmission rate between the target ue and the available optical access point according to the signal to interference plus noise ratio of the available optical access point further includes:
s301: obtaining a value range of the order of pulse amplitude modulation according to the signal-to-interference-plus-noise ratio, the signal error rate and the signal modulation mode of the available optical access node;
s302: taking the maximum value in the value range as the order of pulse amplitude modulation;
s303: and obtaining the data transmission rate between the target user equipment and the available optical access point according to the pulse amplitude modulation order and the signal modulation bandwidth.
Assuming baseband transmission without subcarrier modulation, pulse amplitude modulation with M-order (M-PAM) is used. Based on the signal to interference plus noise ratio, the signal error rate and the signal modulation scheme, the order of the maximum affordable pulse amplitude modulation that can maintain the set error rate can be determined.
In embodiments herein, the data transmission rate between the target user device and the available optical access point is calculated by the following formula:
wherein ,
for the data transmission rate between the target user equipment and the available optical access point at the current scheduling time, B is the signal modulation bandwidth, M is the order of pulse amplitude modulation, ρ=1, and is the cosine pulse roll-off factor.
In this embodiment, referring to fig. 4, the obtaining the weighted evaluation value of the target ue according to the data transmission rate between the target ue and all the available optical access points thereof further includes:
s401: obtaining an evaluation value of the target user equipment according to the data transmission rate between the target user equipment and all the available optical access points;
s402: and obtaining the weighted evaluation value of the target user equipment according to the evaluation values of the other user equipment and the target user equipment.
Specifically, referring to fig. 5, the obtaining, according to the data transmission rate between the target ue and all the available optical access points thereof, the evaluation value of the target ue further includes:
s501: obtaining the total data transmission rate of the target user equipment according to the data transmission rates between the target user equipment and all the available optical access points;
s502: according to the total data transmission rate of the target user equipment and the scheduling condition of the target user equipment in the last scheduling moment, calculating to obtain the long-term average throughput between the target user equipment and all the available optical access points thereof;
S503: and calculating an evaluation value of the target equipment according to the total data transmission rate of the target user equipment and the long-term average throughput between the target user equipment and all the available optical access points thereof.
For the target user equipment, the data transmission rate between the target user equipment and any available optical access point corresponding to the target user equipment can be obtained through calculation according to the formula, and the total data transmission rate of the target user equipment can be obtained by summing the data transmission rates between all available optical access points corresponding to the target user equipment. The long-term average throughput between the target user equipment and all the available optical access points is calculated according to the following formula:
the long-term average throughput between the target user device and all of its available optical access points is calculated by the following formula:
wherein ,TF For the duration between two adjacent scheduling moments, t is the current scheduling moment,
setting for target user in last scheduling timeLong-term average throughput between the device and all its available optical access points, < >>
The total data transmission rate of the target user equipment; if the target UE communicates with all available optical access points in the last scheduling time, the target UE is +. >
If the target UE does not communicate with its available optical access point in the last scheduling time, then +.>
。
Further, the evaluation value of the target device may be calculated by the following formula:
wherein ,
for the evaluation value of the target device at the current scheduling instant, < >>
For the total data transmission rate of the target user equipment at the current scheduling instant,/or->
The long term average throughput between the target user equipment and all of its available optical access points at the current scheduling instant.
In this embodiment, referring to fig. 6, the obtaining the weighted evaluation value of the target ue according to the evaluation values of the other ue and the target ue further includes:
s601: the number of the other user equipment is taken as the association number of the target user equipment;
s602: and carrying out weighted calculation on the evaluation value of the target user equipment based on the association number of the target user equipment to obtain the weighted evaluation value of the target user equipment.
Since there may be more than one other user equipment, the number of the other user equipment may be taken as the association number of the target user equipment, and dividing the evaluation value of the target user equipment by the association number is another process of weighting calculation, so as to obtain the weighted evaluation value of the target user equipment.
The weighted evaluation value of the target user equipment can be obtained through the above method, and it should be noted that the weighted evaluation value of other user equipment can also be obtained through calculation through the above method, and the calculation method of other user equipment is the same as that of the target user equipment, and is not described in detail herein. That is, the weighted evaluation value of any one of the user equipments a may be calculated by the steps herein, and when calculating the weighted evaluation value of any one of the user equipments a, the user equipments having the available optical access points coincident therewith may be considered as other user equipments with respect to the user equipment a, and the user equipment a may be considered as the target user equipment.
Further comparing the calling method in the prior art and the calling method of the embodiments herein:
fixed regular shaped cells include regular cells and merged cells. A conventional cell in this context refers to an area covered by one optical access node, and has both co-channel multiplexing (UFR) and non-co-channel multiplexing.
Referring to fig. 7, for the same frequency multiplexing under the cell-centered fixed-shape cell scheduling in the prior art, all cells use the same frequency f, the hatched area indicates the overlapping area of the cells, and the same frequency interference (ICI) is unavoidable, and the triangular point in the figure receives inter-cell interference (ICI) from the other three neighboring cells. Reducing the field of view (FOV) may be employed to mitigate ICI, but Downlink (DL) user equipment moves between optical access points because of significant performance degradation moving to areas where line of sight propagation cannot cover. The user equipment can be accessed in a time-sharing mode according to the fairness principle or the system capacity maximum principle, but the scheduling mechanism has high complexity and is not beneficial to the expansion of a large-scale network.
As shown in fig. 8, for the non-common frequency multiplexing with a frequency taking factor of 2 (FR-2) in the prior art, adjacent cells use orthogonal frequencies f, respectively 1 and f2 The first level neighbor cell ICI can be avoided and the second level neighbor cell ICI can be ignored, triangle points in the figure can remove ICI from neighbor cells B and C. But the spectrum utilization (BE) of the system is reduced due to the use of multiple frequencies, and the user experience is reduced by switching frequencies (switching cells) once every few meters.
The combined cell is to combine several adjacent cells into one large cell, so that the interference area is reduced, the mobility is improved, and joint transmission (CT) or Vector Transmission (VT) can be adopted for the overlapping part of the cell coverage areas.
As shown in fig. 9, for the prior art cell coverage overlap portion with joint transmission, a and B are combined into one cell, the overlapping region of which transmits the same signal as a single source, so that the potential ICI is advantageously converted into useful signals that may be combined, the cell edge in fig. 1 being the cell center in fig. 3. Multiple APs within the overlapping range of the combined cell serve only a single user at a time, and spectrum utilization (BE) is reduced.
As shown in fig. 10, vector transmission is adopted for the cell coverage overlapping part in the prior art, and multiple users can BE simultaneously served in the cell overlapping region by adopting VT based on Zero Forcing (ZF), so that the problem of BE reduction is solved. I.e. ICI is cancelled at the transmitter in advance, so that multiple users receive signals that do not interfere with each other, requiring the DC attenuation matrix and user data to be shared between APs. But this approach is more complex and may fail when the user is locally dense.
A schematic diagram as shown in fig. 11 is obtained by the method described in the embodiments herein, representing the formation of user-centric non-fixed regular-shape cells, wherein triangles represent certain user equipments. Triangle point A with a dotted line boundary and triangle point B at the right lower part have coincident available optical access points, when the weighted evaluation value of triangle point B is larger than triangle point A, the triangle point A prohibits communication with the available optical access points, the triangle point B forms a cell, and complex Zero Forcing (ZF) -based Vector Transmission (VT) is not adopted by joint transmission (CT), so that the triangle point B is scheduled in a parallel mode for other user equipment corresponding to the non-coincident available optical access points.
As shown in fig. 12, UFR, FR-2, CT-2, VT-2 respectively represent experiments performed by using the same frequency multiplexing under cell-centered fixed shape cell scheduling, non-same frequency multiplexing with FR factor of 2, joint transmission for the cell coverage overlapping portion, and vector transmission for the cell coverage overlapping portion, and UC is an experiment performed by the user-centered multi-user scheduling method proposed in the present embodiment. The increase in FOV results in an expansion of ICI coverage area, different cell formation designs and average user throughput at different FOVs, comparing the average user throughput for the 5 methods, where the average user throughput for the methods herein performs best.
As shown in fig. 13, by introducing different occlusion probabilities P at 120 degree field angle block Indicating the probability that the optical communication path is blocked, VLC blocking will cause the user to experience a reduced data rate, the downlink data rate becomes
R is the downlink rate for line-of-sight communications, assuming that all line-of-sight communications paths are occluded with equal probability, the average user throughput decreases as the occlusion probability increases. The average user throughput of the embodiment of the invention is always better than the prior art.
As shown in fig. 14, the Service Fairness Index (SFI) indicates the difference between the maximum value and the minimum value among the throughput of all users, and when the SFI is low, the throughput difference of different users is small, so that the user equipment is considered to be fairly served. Fig. 14 is a schematic diagram of SFI at 120 degrees of field of view, where embodiments of the present invention may provide a higher average user throughput while having a smaller SFI, as much as possible to meet fairness services.
Based on the above-mentioned multi-user scheduling method based on visible light communication, the embodiment herein also provides a multi-user scheduling device based on visible light communication. The described devices may include systems (including distributed systems), software (applications), modules, components, servers, clients, etc. that employ the methods described in embodiments herein in combination with the necessary devices to implement the hardware. Based on the same innovative concepts, the embodiments herein provide for devices in one or more embodiments as described in the following examples. Since the implementation of the device for solving the problem is similar to the method, the implementation of the device in the embodiment herein may refer to the implementation of the foregoing method, and the repetition is not repeated. As used below, the term "unit" or "module" may be a combination of software and/or hardware that implements the intended function. While the means described in the following embodiments are preferably implemented in software, implementation in hardware, or a combination of software and hardware, is also possible and contemplated.
Specifically, fig. 15 is a schematic block diagram of an embodiment of a multi-user scheduling apparatus based on visible light communication provided in this embodiment, and referring to fig. 15, a multi-user scheduling apparatus based on visible light communication provided in this embodiment has a plurality of optical access points distributed in an area, where the multi-user scheduling apparatus includes: the available optical access point determination module 100, the weighted priority value determination module 200, the scheduling module 300.
The available light access point determining module 100 is configured to use, as an available light access point of the user equipment, light access points of all light access points having an incident angle to the user equipment smaller than an angle of view of the user equipment when the current scheduling time arrives;
the weighted priority value determining module 200 is configured to obtain a weighted evaluation value of a target user equipment according to a data transmission rate between the target user equipment and all available optical access points of the target user equipment when the available optical access points of the target user equipment coincide with available optical access points of other user equipment; obtaining weighted evaluation values of the other user equipment according to the data transmission rates between the other user equipment and all the available optical access points;
a scheduling module 300, configured to allow the target ue to communicate with all available optical access points thereof when the weighted priority value of the target ue is greater than that of the other ue, where the all available optical access points perform joint transmission; the other user device is prohibited from communicating with its available optical access point.
Referring to fig. 16, a computer device 402 is further provided in an embodiment of the present disclosure based on a multi-user scheduling method based on visible light communication as described above, where the method is executed on the computer device 402. The computer device 402 may include one or more processors 404, such as one or more Central Processing Units (CPUs) or Graphics Processors (GPUs), each of which may implement one or more hardware threads. The computer device 402 may also comprise any memory 406 for storing any kind of information, such as code, settings, data, etc., and in a particular embodiment a computer program on the memory 406 and executable on the processor 404, which computer program, when being executed by the processor 404, may execute instructions according to the method described above. For example, and without limitation, memory 406 may include any one or more of the following combinations: any type of RAM, any type of ROM, flash memory devices, hard disks, optical disks, etc. More generally, any memory may store information using any technique. Further, any memory may provide volatile or non-volatile retention of information. Further, any memory may represent fixed or removable components of computer device 402. In one case, when the processor 404 executes associated instructions stored in any memory or combination of memories, the computer device 402 can perform any of the operations of the associated instructions. The computer device 402 also includes one or more drive mechanisms 408 for interacting with any memory, such as a hard disk drive mechanism, optical disk drive mechanism, and the like.
The computer device 402 may also include an input/output module 410 (I/O) for receiving various inputs (via an input device 412) and for providing various outputs (via an output device 414). One particular output mechanism may include a presentation device 416 and an associated graphical user interface 418 (GUI). In other embodiments, input/output module 410 (I/O), input device 412, and output device 414 may not be included, but merely as a computer device in a network. Computer device 402 may also include one or more network interfaces 420 for exchanging data with other devices via one or more communication links 422. One or more communication buses 424 couple the above-described components together.
The communication link 422 may be implemented in any manner, for example, through a local area network, a wide area network (e.g., the internet), a point-to-point connection, etc., or any combination thereof. Communication link 422 may include any combination of hardwired links, wireless links, routers, gateway functions, name servers, etc., governed by any protocol or combination of protocols.
Corresponding to the method in fig. 1-7, embodiments herein also provide a computer readable storage medium having stored thereon a computer program which, when executed by a processor, performs the steps of the above method.
Embodiments herein also provide a computer readable instruction wherein the program therein causes the processor to perform the method as shown in fig. 1 to 7 when the processor executes the instruction.
It should be understood that, in the various embodiments herein, the sequence number of each process described above does not mean the sequence of execution, and the execution sequence of each process should be determined by its functions and internal logic, and should not constitute any limitation on the implementation process of the embodiments herein.
It should also be understood that in embodiments herein, the term "and/or" is merely one relationship that describes an associated object, meaning that three relationships may exist. For example, a and/or B may represent: a exists alone, A and B exist together, and B exists alone. In addition, the character "/" herein generally indicates that the front and rear associated objects are an "or" relationship.
Those of ordinary skill in the art will appreciate that the elements and algorithm steps described in connection with the embodiments disclosed herein may be embodied in electronic hardware, in computer software, or in a combination of the two, and that the elements and steps of the examples have been generally described in terms of function in the foregoing description to clearly illustrate the interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure.
It will be clear to those skilled in the art that, for convenience and brevity of description, specific working procedures of the above-described systems, apparatuses and units may refer to corresponding procedures in the foregoing method embodiments, and are not repeated herein.
In the several embodiments provided herein, it should be understood that the disclosed systems, devices, and methods may be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative, e.g., the division of the units is merely a logical function division, and there may be additional divisions when actually implemented, e.g., multiple units or components may be combined or integrated into another system, or some features may be omitted or not performed. In addition, the coupling or direct coupling or communication connection shown or discussed with each other may be an indirect coupling or communication connection via some interfaces, devices, or elements, or may be an electrical, mechanical, or other form of connection.
The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the elements may be selected according to actual needs to achieve the objectives of the embodiments herein.
In addition, each functional unit in the embodiments herein may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit. The integrated units may be implemented in hardware or in software functional units.
The integrated units, if implemented in the form of software functional units and sold or used as stand-alone products, may be stored in a computer readable storage medium. Based on such understanding, the technical solutions herein are essentially or portions contributing to the prior art, or all or portions of the technical solutions may be embodied in the form of a software product stored in a storage medium, including several instructions to cause a computer device (which may be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in the embodiments herein. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a random access Memory (RAM, random Access Memory), a magnetic disk, or an optical disk, or other various media capable of storing program codes.
Specific examples are set forth herein to illustrate the principles and embodiments herein and are merely illustrative of the methods herein and their core ideas; also, as will be apparent to those of ordinary skill in the art in light of the teachings herein, many variations are possible in the specific embodiments and in the scope of use, and nothing in this specification should be construed as a limitation on the invention.
Claims (10)
1. A multi-user scheduling method based on visible light communication is characterized in that a plurality of optical access points are distributed in a region range, and the multi-user scheduling method comprises the following steps:
when the current scheduling time comes, taking the optical access points with the incidence angles to the user equipment smaller than the field angle of the user equipment in all the optical access points as the available optical access points of the user equipment;
when the available light access points of the target user equipment are overlapped with the available light access points of other user equipment, obtaining a weighted evaluation value of the target user equipment according to the data transmission rate between the target user equipment and all the available light access points of the target user equipment; obtaining weighted evaluation values of the other user equipment according to the data transmission rates between the other user equipment and all the available optical access points;
When the weighted evaluation value of the target user equipment is larger than that of the other user equipment, allowing the target user equipment to communicate with all available optical access points thereof, wherein all available optical access points corresponding to the target user equipment comprise available optical access points overlapped with the other user equipment; inhibit the other user devices from communicating with their available optical access points;
when the weighted evaluation value of the target user equipment is smaller than or equal to that of other user equipment, the overlapped available optical access points are communicated with other user equipment, and the target user equipment is forbidden to communicate with the available optical access points;
when the available optical access points of the target user equipment are not overlapped with the available optical access points of other user equipment, allowing the target user equipment to communicate with all the available optical access points of the target user equipment, wherein all the available optical access points perform joint transmission; at this time, the communication condition of other user equipment cannot be determined, any other user equipment needs to be further used as a new target user equipment, and whether the available optical access point of the new target user equipment coincides with the available optical access point of the new other user equipment is judged.
2. The method for multiuser scheduling based on visible light communication according to claim 1, wherein the method for determining the data transmission rate between the target user equipment and its available optical access points comprises:
obtaining a total direct current attenuation value of an optical channel of the available optical access point according to the incident angle of the available optical access point to target user equipment and the field angle of the target user equipment;
obtaining the signal-to-interference-plus-noise ratio of the available optical access point according to the receiving power of the target user equipment and the total direct current attenuation value of the optical channel;
and obtaining the data transmission rate between the target user equipment and the available optical access point according to the signal to interference plus noise ratio of the available optical access point.
3. The method for multiuser scheduling based on visible light communication according to claim 2, wherein the obtaining the total dc attenuation value of the optical channels of the available optical access points according to the incident angle of the available optical access points to the target user equipment and the view angle of the target user equipment further comprises:
the total dc attenuation value of the optical channels of the optical access point is calculated by the following formula:
wherein ,
，/>
half-power angle for available light access point, +.>
For the full power angle of the available optical access point, < >>
Gain of optical filter and optical concentrator, respectively,/->
，
N is the reflection index of the optical concentrator, < ->
For the angle of incidence of the available optical access point to the target user equipment +.>
For the angle of view of the target user device, r is the distance from the available optical access point to the target user device, D PA Is the physical area of the available optical access point.
4. The method for multiuser scheduling based on visible light communication according to claim 3, wherein the obtaining the signal-to-interference-plus-noise ratio of the available optical access point according to the received power of the target user equipment and the total dc attenuation value of the optical channel further comprises:
the signal to interference plus noise ratio of an available optical access point is calculated by the following formula:
wherein 
G (j) is the j th row of the matrix G, H is the total DC attenuation value of the optical channels of the available optical access points, N is the total number of available optical access points, N 0 The noise power spectral density, B is the signal modulation bandwidth, gamma is the photoelectric conversion efficiency, +.>
，N shot Is the noise power spectral density of the optical signal, which is of the order of 10 -22 Q is electron charge, I a (P r,i ) For photocurrent at the target user equipment, S S S for an available optical access point belonging to a signal set I Is an available optical access point belonging to the interference set.
5. The method for multiuser scheduling based on visible light communication according to claim 4, wherein the obtaining the data transmission rate between the target ue and the available optical access point according to the signal-to-interference-plus-noise ratio of the available optical access point further comprises:
obtaining a value range of the order of pulse amplitude modulation according to the signal-to-interference-plus-noise ratio, the signal error rate and the signal modulation mode of the available optical access point;
taking the maximum value in the value range as the order of pulse amplitude modulation;
and obtaining the data transmission rate between the target user equipment and the available optical access point according to the pulse amplitude modulation order and the signal modulation bandwidth.
6. The method for multiuser scheduling based on visible light communication according to claim 1, wherein the obtaining the weighted evaluation value of the target ue according to the data transmission rates between the target ue and all the available optical access points thereof further comprises:
obtaining an evaluation value of the target user equipment according to the data transmission rate between the target user equipment and all the available optical access points;
And obtaining the weighted evaluation value of the target user equipment according to the evaluation values of the other user equipment and the target user equipment.
7. The method for multiuser scheduling based on visible light communication according to claim 6, wherein the obtaining the evaluation value of the target ue according to the data transmission rate between the target ue and all the available optical access points thereof further comprises:
obtaining the total data transmission rate of the target user equipment according to the data transmission rates between the target user equipment and all the available optical access points;
according to the total data transmission rate of the target user equipment and the scheduling condition of the target user equipment in the last scheduling moment, calculating to obtain the long-term average throughput between the target user equipment and all the available optical access points thereof;
and calculating an evaluation value of the target user equipment according to the total data transmission rate of the target user equipment and the long-term average throughput between the target user equipment and all the available optical access points thereof.
8. The method for scheduling multiple users based on visible light communication according to claim 7, wherein the calculating the long-term average throughput between the target ue and all available optical access points thereof according to the total data transmission rate of the target ue and the scheduling situation of the target ue at the previous scheduling time further comprises:
The long-term average throughput between the target user device and all of its available optical access points is calculated by the following formula:
wherein ,TF For the duration between two adjacent scheduling moments, t is the current scheduling moment,
for the long-term average throughput between the target user equipment and all its available optical access points in the last scheduling instant +.>
The total data transmission rate of the target user equipment; if the target UE communicates with all available optical access points in the last scheduling time
If the target UE does not communicate with its available optical access point in the last scheduling time, then +.>
。
9. The method for multiuser scheduling based on visible light communication according to claim 6, wherein the obtaining the weighted evaluation value of the target ue according to the evaluation values of the other ue and the target ue further comprises:
the number of the other user equipment is taken as the association number of the target user equipment;
and carrying out weighted calculation on the evaluation value of the target user equipment based on the association number of the target user equipment to obtain the weighted evaluation value of the target user equipment.
10. A multi-user scheduling device based on visible light communication, characterized in that a plurality of optical access points are distributed in a region, the multi-user scheduling device comprising:
The available light access point determining module is used for taking light access points with incidence angles smaller than the field angle of the user equipment in all light access points as available light access points of the user equipment when the current scheduling time arrives;
the weighting priority value determining module is used for obtaining a weighting evaluation value of the target user equipment according to the data transmission rate between the target user equipment and all the available light access points of the target user equipment when the available light access points of the target user equipment are overlapped with the available light access points of other user equipment; obtaining weighted evaluation values of the other user equipment according to the data transmission rates between the other user equipment and all the available optical access points;
a scheduling module, configured to allow the target ue to communicate with all available optical access points thereof when the weighted priority value of the target ue is greater than that of the other ue, where all available optical access points corresponding to the target ue include available optical access points that overlap with the other ue; inhibit the other user devices from communicating with their available optical access points;
When the weighted evaluation value of the target user equipment is smaller than or equal to that of other user equipment, the overlapped available optical access points are communicated with other user equipment, and the target user equipment is forbidden to communicate with the available optical access points;
when the available optical access points of the target user equipment are not overlapped with the available optical access points of other user equipment, allowing the target user equipment to communicate with all the available optical access points of the target user equipment, wherein all the available optical access points perform joint transmission; at this time, the communication condition of other user equipment cannot be determined, any other user equipment needs to be further used as a new target user equipment, and whether the available optical access point of the new target user equipment coincides with the available optical access point of the new other user equipment is judged.
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