Multi-cell resource allocation method based on interference management in indoor VLC-WiFi heterogeneous networks

Abstract

The present invention relates to a multi-cell resource allocation method based on interference management in an indoor VLC-WiFi heterogeneous network, and belongs to the field of optical wireless communication technology. The method of the present invention can optimize the spectrum resource allocation of indoor VLC-WiFi. According to the user rate requirement, channel capacity and the interference influence of adjacent users, the interference influence factor between each user and each VLC access point is designed to determine the order in which users select VLC access points and the order in which they obtain resource allocation; according to the user's signal-to-interference-noise ratio value, user rate requirement value and channel capacity value, the user's priority factor is evaluated to determine the priority of VLC AP in selecting users; in the multi-cell resource allocation stage, VLC access points and multi-cell spectrum resources are selected for each user according to the priority factor and the interference influence factor; for users who fail to access the VLC AP, a wireless channel gain ratio allocation method for WiFi resources is adopted. This method can promote the rational allocation of spectrum resources in indoor VLC-WiFi heterogeneous networks and improve system throughput and user satisfaction.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical wireless communications and relates to a multi-cell resource allocation method based on interference management in an indoor VLC-WiFi heterogeneous network for downlink transmission of information. Background Art

[0002] In recent years, with the commercial deployment of 5G, emerging applications in intelligent scenarios have emerged in droves, and the demand for highly differentiated smart terminals has become increasingly pronounced. However, the rapidly growing wireless data traffic will eventually reach a certain limit within the limited 5G bandwidth resources. Therefore, for 6G, exploring different frequency bands to address spectrum shortages is particularly important. As a key component of future 6G wireless communication systems, visible light communication (VLC) technology, with its vast available bandwidth, ultra-high transmission rates, and superior coverage, provides an indispensable solution for achieving 6G's goals of ultra-high speed, ultra-low latency, and ultra-large connections. Multi-color VLC systems, constructed using multi-color light-emitting diodes (LEDs), provide users with even higher data rates. One of the core goals of 6G technologies is to build an integrated network to achieve "full spectrum, full coverage, and full application" communications. Multi-color VLC is one of the most promising next-generation wireless communication technologies for achieving this goal, truly realizing the "Internet of Everything." Furthermore, the integration of radio frequency (RF) communication technology and multi-color VLC will promote the coordinated development of various communication technologies in 6G, thereby promoting spectrum resource sharing and supplementation based on 5G, and enabling the development of IoT applications to a deeper level. Wireless Fidelity (WiFi), a widely used RF technology, integrates with VLC to form multi-color VLC-WiFi, which incorporates the design concepts of the basic 6G physical layer architecture and is currently receiving extensive research in academia. Given that 80% of future communications will occur indoors, indoor multi-color VLC-WiFi heterogeneous networks can serve users in a multi-cell format, meeting the differentiated data rate requirements of indoor users and enabling cell densification to meet rapidly growing capacity demands. This is a leading trend in future wireless network deployment. Indoor multi-color VLC-WiFi heterogeneous networks deploy a large number of VLC access points (APs) to serve different users, transforming the entire indoor area into multiple overlapping VLC AP cells. However, the inter-cell interference (ICI) generated by spectrum reuse between cells has a significant impact on some users. The dense deployment of cells and the irregular distribution of user locations make interference management more difficult, significantly impacting spectrum resource utilization. Therefore, in indoor multi-color VLC-WiFi heterogeneous networks, resource allocation must be based on interference management to achieve a good balance between spectrum reuse and ICI, while also addressing the diverse user rate requirements. This ensures user satisfaction, system fairness, and improved throughput performance. Summary of the Invention

[0003] In view of this, the core of the present invention is to provide a multi-cell resource allocation method based on interference management in indoor VLC-WiFi heterogeneous networks, which improves system throughput while ensuring user satisfaction and system fairness.

[0004] In order to achieve the above object, the present invention provides the following technical solutions:

[0005] A multi-cell resource allocation method based on interference management in an indoor VLC-WiFi heterogeneous network, characterized in that the method comprises the following steps:

[0006] S1: Determine the user set U, VLC access point set A, and VLC multi-color spectrum set in the indoor VLC-WiFi, and input the required rate of each user as r i , i∈U, VLC AP transmit power is P vlc , the WiFi access point transmission power is P wifi , initialize the WiFi AP-user association matrix F = [f 1i ] 1×|U| And the visible light band allocation matrix M=[m kj ] 3×|A| ; Based on the VLC Lambertian radiation model, calculate the optical channel gain from each user to each VLC access point, and based on the Rayleigh fading channel model, calculate the wireless channel gain from the user to the WiFi access point;

[0007] S2: Calculate the positive impact q between user i and VLC AP j according to Shannon's formula i,j , j∈A, define q i,j The main user set is Y i,j ,q i,j The secondary user set is Z i,j , executing the VLC AP selection algorithm based on interference avoidance for each user and each VLC AP in turn, obtaining the interference impact factor between each user and each VLC AP, and determining the order of selecting the VLC APs in ascending order for each user according to the size of the impact factor;

[0008] S3: Construct a set of VLC APs whose receiving SINR (Signal to Interference plus Noise Ratio) value to user i is greater than 1 in the system, denoted as K i , i∈U,K i represents the set of VLC APs that can be associated with user i; according to the Shannon formula, the relationship between user i and K is calculated. i The positive impact between i , construct q i The main user set Y i for: Determine the priority factor θ for user i to select VLC AP i , repeat step S3 to generate the priority factor of each user, and sort the users in descending order according to the priority factor;

[0009] S4: Based on the interference impact factor obtained in S2 and the user priority factor obtained in S3, the multi-cell resource allocation algorithm based on interference management is executed for each user in turn, and the VLC AP or WiFi AP connection information and spectrum resource allocation status selected by all users are output;

[0010] The calculation method of the optical channel gain and the wireless channel gain in the above-mentioned S1 is:

[0011] S101: Calculate the optical channel gain between user i and VLC AP j based on the Lambertian radiation model The calculation formula is:

[0012]

[0013] In the above formula, A PD Indicates the receiving area of ​​the optical receiver, the Lambertian radiation coefficient is the half-power angle of LED (Light-emitting Diode), d i,j is the straight-line distance between PD (Photodetector) i and LED j, is the emission angle of LED j, ψ is the receiving angle of PD i, ψ c is the receiver field of view angle, T(ψ) is the optical filtering gain of the receiver, and g(ψ) is the optical aggregation gain of the receiver;

[0014] S102: Calculate the wireless channel gain between WiFi AP j and user i based on the Rayleigh fading model The calculation formula is:

[0015]

[0016] In the above formula, h r is the small-scale fading gain, which obeys the Rayleigh distribution with an average power of 2.46 dB, L(d i,j ) is the large-scale fading loss, in dB, and its expression is:

[0017]

[0018] In the above formula, L FS (d i,j ) is the path loss of radio waves in free space, and its value is LFS (d i,j )=20lg(f c d i,j )-147.5, in dB, shadow fading X σ is a zero-mean Gaussian random variable with a standard deviation of 3dB, f c is the center carrier frequency of the WiFi AP, which is 2.4GHz, d i,j is the communication link distance from WiFi AP j to user i, d ref is the reference distance, its value is 10m;

[0019] The specific process of S2 mentioned above is:

[0020] S201: Calculate the channel capacity R from VLC AP j to user i according to Shannon's formula i,j , i∈U, j∈A, R i,j As the positive influence q between user i and VLC AP j i,j Value, that is, R i,j =q i,j ;

[0021] Among them, q i,j The calculation formula is:

[0022]

[0023] In the above formula, is the channel bandwidth provided by VLC AP j to user i, γ is the photoelectric conversion coefficient of the PD receiving signal of user i, is the optical transmission power allocated to user i by VLC AP j, is the noise power spectral density of the VLC system;

[0024] S202: Calculate the SINR value between VLC AP j and user i User i receives All VLCAPs with values ​​greater than 1 are stored in the set K i In, K i Represents the set of VLC APs that can be associated with user i; All users greater than 1 are stored in the set H j In the example, the candidate user set of VLC AP j will not include H of user i. j All other users in the VLC AP j are considered as the primary user set Y of user i that can be associated with VLC AP j. i,j , that is: Y i,j =H j \i, calculate the positive influence q between user i and VLC AP j i,jFor the main user set Y i,j The negative impact caused by the primary user i' value;

[0025] Among them, VLC AP j to user i and The calculation formulas are:

[0026]

[0027]

[0028] S203: Calculate the positive influence q between user i and VLC AP j i,j For the main user set Y i,j The negative impact of the weight caused by the main user i' value;

[0029] in, The calculation formula is:

[0030]

[0031] In the above formula, r max is the maximum demand rate of all users in the entire system, r min is the minimum required rate of all users in the entire system, r base The basic rate requirement of the user is set to 5Mbps, r i' is the data rate requirement of user i';

[0032] S204: K i The candidate user sets of all VLC AP j's except VLC AP j are merged, and H j The associated users in the VLC AP j are obtained by obtaining the secondary user set that user i can associate with, and using Z i,j Indicates that

[0033] S205: Calculate the positive influence q between user i and VLC AP j i,j For the secondary user set Z i,j Negative impact caused by secondary user i value;

[0034] in, The value is calculated as:

[0035]

[0036] S206: Calculate the positive influence q between user i and VLC AP j i,j For the secondary user set Zi,j The negative impact of the weight caused by the secondary user i value;

[0037] in, The value is calculated as:

[0038]

[0039] S207: Calculate the positive influence q between user i and VLC AP j i,j The total negative weight W caused to all users i,j value;

[0040] Among them, W i,j The value is calculated as:

[0041]

[0042] S208: Calculate the interference impact factor α between user i and VLC AP j i,j value;

[0043] Among them, α i,j The value is calculated as:

[0044]

[0045] S209: Repeat steps S201 to S208 to calculate the interference impact factor between each user and each VLC AP, and form an impact factor matrix α = [α i,j ] |U|×|A| ;

[0046] The specific steps of the above S3 are:

[0047] S301: Calculate the set K of VLC APs that user i can associate with i The positive impact q of all VLC APs on user i in i ;

[0048] Among them, q i The value is calculated as:

[0049]

[0050] S302: For K i All VLC APs in the system are associated with user set H. j Merge, then subtract user i from the merged set to generate positive influence q i The main user set Y i ;

[0051] Among them, the main user set Y of user ii The calculation formula is:

[0052]

[0053] S303: Calculate user i and K i The positive impact of VLC AP in the i For the main user set Y i The negative impact caused by other primary users i' value;

[0054] in, The calculation formula is:

[0055]

[0056] S304: Calculate user i and K i The positive impact between i For the main user set Y i The negative weight W caused by the primary user i' i i' value;

[0057] Among them, W i i' The calculation formula is:

[0058]

[0059] S305: Calculate user i and K i The positive impact between i The total weighted negative impact W on all users i value;

[0060] W i The calculation formula is:

[0061]

[0062] S306: Calculate the priority factor θ for user i to select the VLC AP i ;

[0063] Among them, θ i The calculation method is:

[0064]

[0065] S307: Repeat the operations from S301 to S306 to calculate the priority factor of each user in the set U in turn, and then calculate the priority factor θ according to the priority factor θ. i Arrange users in descending order to generate a priority order for users to select APs;

[0066] The specific process of S4 mentioned above is:

[0067] S401: Traverse the associated VLC AP j of user i in U in sequence, j∈K i If the interference factor between user i and VLC AP j is greater than the interference factor between VLC AP j and other users, then VLC AP j is removed from K i Delete from and get the candidate VLC AP set D for user i i , where other users here refer to users with a smaller priority factor than user i and located in H j Users within;

[0068] S402: Traverse candidate VLC AP j of user i in sequence, j∈D i , if the interference factor α between user i and VLC AP j i,j Less than the average impact factor between VLC AP j and other user i' Then add VLC AP j to the primary candidate VLC AP set Q of user i i Here, other users refer to those with a smaller priority factor than user i and located in H j User i* in the, that is, i*∈(U i ∩H j ), U i is the set of users with a smaller priority factor than user i;

[0069] S403: Repeat steps S401 and S402 to obtain a candidate VLC AP set D for each user in U i and the primary candidate VLCAP set Q i , if user i’s candidate VLC AP set D i If is an empty set, then user i is connected to the WiFi AP, i∈U;

[0070] S404: According to the priority factor θ i Select user i in descending order, and sort the candidate VLC AP set D of user i according to the interference impact factor between user i and VLC AP in descending order. i Sort them and allocate an available visible light band to the user in the order of the spectrum resources of each VLC AP, including red light band, green light band, and blue light band. If a certain VLC AP j is the main candidate VLC AP for user i, that is: VLC AP j∈Q i, the VLC AP j allocates two available visible light bands to user i until the user's required rate is met or there is no available visible light band. The available visible light band refers to the remaining visible light band of VLC AP j. If the remaining visible light band is allocated to user i without causing interference to other users, then this visible light band is the available visible light band of user i. The other users here refer to the users who have been allocated visible light bands and are located in H j For users in , if user i cannot obtain the available visible light bands of all VLC APs, user i is associated with the WiFi AP;

[0071] S405: Repeat step S404 until all users are traversed; the visible light band allocation matrix M of the VLC AP is [m kj ] 3×|A| Assignment, k = 1, 2, 3, respectively represent the red light band, green light band, blue light band of VLC AP, j represents the sequence number of VLCAP, element value m kj =i represents that the visible light band k of VLC AP j is allocated to user i; for the WiFi AP-user association matrix F = [f 1i ] 1×|U| Assignment, f 1i =1 means user i is associated with WiFi AP, f 1i =0 means user i is not associated with the WiFi AP, and the WiFi frequency band resources are allocated to users accessing the WiFi based on the ratio of the channel gain between the user and the WiFi;

[0072] S406: According to W i,j Value, calculate the average total weighted negative influence value of each user i From W i,j The user with the largest value starts to traverse in sequence, j∈D i , calculate user i in D i The average weighted negative impact on If user i’s weight on VLC AP j has a negative impact W i,j Value greater than And VLC AP j is in the primary candidate VLC AP set Q of user i i In the case of VLCAP j, the remaining visible light band k* of VLCAP j is directly allocated to user i, and m is set to k*j =i, until all users have traversed or all VLCAPs have no available light wave bands, update the visible light band allocation matrix M = [m kj ] 3×|A|; Calculate the cumulative channel capacity of all users to the associated VLCAP or WiFi AP to obtain the system throughput; Calculate the cumulative channel capacity of all users to the associated VLC AP or WiFi AP to obtain the system throughput;

[0073] S407: Output the visible light band allocation matrix M = [m kj ] 3×|A| , WiFi AP-user association matrix F=[f 1i ] 1×|U| And WiFi frequency band resource allocation and system throughput.

[0074] The beneficial effects of the present invention are as follows: the present invention relates to a multi-cell resource allocation method based on interference management in an indoor VLC-WiFi heterogeneous network. First, using user location and user required rate as input parameters, a control center generates an interference impact factor between each user and each VLC AP, and determines a VLC AP selection order for each user based on the impact factor. Simultaneously, a priority factor is generated for each user, and a priority order is determined for each user based on the priority factor. Next, for each user's associable VLC AP set, a candidate VLC AP set and a candidate primary VLC AP set are generated for each user. Then, a VLC AP and a visible light frequency band are selected for each user based on the impact factor and the priority factor. After that, the user is associated with the WiFi AP according to a WiFi AP supplementation strategy. Finally, a visible light frequency band is supplemented and allocated to the user according to the visible light frequency band supplementation strategy, further improving system throughput. BRIEF DESCRIPTION OF THE DRAWINGS

[0075] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below with reference to the following drawings, in which:

[0076] Figure 1 An example diagram of the downlink model of an indoor multi-color VLC-WiFi heterogeneous network;

[0077] Figure 2 Flowchart of multi-cell resource allocation algorithm based on interference management;

[0078] Figure 3 Flowchart of the user priority assessment algorithm based on user needs; DETAILED DESCRIPTION

[0079] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the content described in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0080] Among them, the accompanying drawings are only for illustrative purposes and represent only schematic diagrams rather than actual pictures, and should not be understood as limiting the present invention. In order to better illustrate the embodiments of the present invention, some parts in the accompanying drawings may be omitted, enlarged or reduced, and do not represent the dimensions of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions may be omitted in the accompanying drawings.

[0081] Attachment Figure 1 This is an example diagram of the downlink model of an indoor multi-color VLC-WiFi heterogeneous network. Multiple VLC APs densely deployed on the ceiling are used for downlink data transmission, and one WiFi AP is used for uplink data transmission and partial downlink data transmission. h represents the height of the receiving device from the ceiling, and h represents the height of the receiving device from the ceiling. PD = represents the ground height of the receiving device, measured in meters. VLC APs are spaced 2.5 meters apart. Each VLC AP consists of a multicolor LED array that emits red (R), green (G), and blue (B). By synthesizing the three colors of RGB light, stable white light illumination is achieved. The R, G, and B LEDs form a multicolor LED light assembly, also known as a multicolor LED array. For convenience, they are generally referred to as LEDs. Each user is equipped with a photoelectric detector (PD) that can receive the three colors of light. The PD acts as a receiver, detecting the VLC multi-spectrum signal from the VLC AP and receiving the data transmitted downlink by the VLC AP to the user. VLC APs and WiFi APs communicate with each other using power line communication (PLC). PLC is used to establish a connection with the multicolor VLC-WiFi heterogeneous network control center. When a VLC AP cannot provide spectrum resources for user communication, the user receives data through the WiFi AP.

[0082] Attachment Figure 2 This is a flowchart of the multi-cell resource allocation algorithm based on interference management, which is described in detail below:

[0083] Input: Input the user set U, VLC access point set A, VLC multi-color spectrum set in indoor VLC-WiFi, and input the required rate of each user as r i and the basic rate r of the users in the system base value, i∈U, VLC AP transmit power is P vlc , the WiFi access point transmission power is P wifi , initialize the WiFi AP-user association matrix F = [f 1i ] 1×|U| And the visible light band allocation matrix M=[m kj ] 3×|A| ;

[0084] Output: visible light band allocation matrix M for all users = [m kj ] 3×|A| , F=[f 1i ] 1×|U| and WiFi spectrum allocation and system throughput.

[0085] Step 1: According to formula (1), the optical channel gain from each user to each VLC access point is calculated using the Lambertian radiation model of VLC. i∈U, j∈A;

[0086] Step 2: According to formula (2), the channel gain from the user to the WiFi access point is calculated using the Rayleigh fading channel model. value, i∈U, j∈A;

[0087] Step 3: Calculate the channel capacity R from VLC AP j to user i using formula (4): i,j , i∈U, j∈A, let R i,j As the positive influence q between user i and VLC AP j i,j Value, that is, R i,j =q i,j ;

[0088] Step 4: Calculate the SINR (Signal to Interference plus Noise Ratio) between VLC AP j and user i using formula (5): User i receives All VLC APs with a value greater than 1 are stored in the set K i In, K i Represents the set of VLC APs that can be associated with user i; All users greater than 1 are stored in the set H j In the example, the candidate user set of VLC APj will not include H of user i. jAll other users in the VLC AP j are considered as the primary user set Y of user i that can be associated with VLC AP j. i,j , that is: Y i,j =H j Repeat step 4 to determine the primary user set Y of all users. i,j , i∈U;

[0089] Step 5: Calculate the positive impact q between user i and VLC AP j using formula (6): i,j For the main user set Y i,j The negative impact caused by the primary user i' Value, i'∈Y i,j , j∈K i , i∈U;

[0090] Step 6: Calculate the positive impact q between user i and VLC AP j using formula (7): i,j For the main user set Y i,j The negative impact of the weight caused by the main user i' Value, i'∈Y i,j , j∈K i , i∈U;

[0091] Step 7: K i The candidate user sets of all VLC AP j's except VLC AP j are merged, and H j The associated users in the VLC AP j are obtained by obtaining the secondary user set that user i can associate with, and using Z i,j Indicates that

[0092] Step 8: Calculate the positive impact q between user i and VLC AP j according to formula (8): i,j For the secondary user set Z i,j Negative impact caused by secondary user i Value, i”∈Z i,j , j∈K i , i∈U;

[0093] Step 9: Calculate the positive impact q between user i and VLC AP j according to formula (9): i,j For the secondary user set Z i,j The negative impact of the weight caused by the secondary user i Value, i”∈Z i,j , j∈K i , i∈U;

[0094] Step 10: Calculate the positive impact q between user i and VLC AP j according to formula (10): i,jThe total negative weight W caused to all users i,j value, i∈U, j∈K i ;

[0095] Step 11: Calculate the interference avoidance factor α associated between user i and VLC AP j according to formula (11): i,j Value i∈U, j∈K i ;

[0096] Step 12: Assign all users i to their associated VLC AP set K i The interference avoidance factor α associated with i,j Saved in an impact factor matrix α, that is, α=[α i,j ] |U|×|A| ;

[0097] Step 13: Execute the attached Figure 3 Based on the user priority assessment algorithm flow chart shown in the figure, the user priority factor θ is obtained. i , i∈U; then according to the priority factor θ i Arrange users in descending order to obtain the priority order of users selecting APs;

[0098] Step 14: Traverse the associated VLC AP j of user i in U, j∈K i If the interference factor between user i and VLC AP j is greater than the interference factor between VLC AP j and other users, then VLC AP j is removed from K i Delete from and get the candidate VLC AP set D for user i i , where other users here refer to users with a smaller priority factor than user i and located in H j User in, i∈U;

[0099] Step 15: Traverse candidate VLC AP j of user i in sequence, j∈D i , if the interference factor α between user i and VLC AP j i,j Less than the average impact factor between VLC AP j and other user i' Then add VLC AP j to the primary candidate VLC AP set Q of user i i Here, other users refer to those with a smaller priority factor than user i and located in H j User i* in the, that is, i*∈(U i ∩H j ), U i is the set of users with a smaller priority factor than user i, i∈U;

[0100] Step 16: If user i's candidate VLC AP set D i If is an empty set, then user i is connected to the WiFi AP, i∈U;

[0101] Step 17: According to the priority factor θ i Select user i in descending order, and sort the candidate VLC AP set D of user i according to the interference impact factor between user i and VLC AP in descending order. i Sort them and allocate an available visible light band k to the user in the order of each VLCAP spectrum resource k: red light band, green light band, blue light band, then m kj =i,j∈D i ; If VLC AP j is the primary candidate VLC AP for user i, that is: VLC AP j∈Q i , then the VLC APj allocates an additional second available visible light band k′ to user i, that is: m k′j =i, until the user's required rate is met or there is no available visible light band; the available visible light band refers to the remaining visible light band of VLC AP j. If the remaining visible light band is allocated to user i without causing interference to other users, then this visible light band is the available visible light band of user i. The other users here refer to the users who have been allocated visible light bands and are located in H j If user i cannot obtain the available visible light bands of all VLC APs, then user i is associated with WiFi AP, i∈U, and f 1i =1;

[0102] Step 18: VLC AP visible light band allocation matrix M = [m kj ] 3×|A| Assignment, k = 1, 2, 3, respectively represent the red light band, green light band, blue light band of VLC AP, j represents the sequence number of VLC AP, element value m kj =i represents that the visible light band k of VLC AP j is allocated to user i; for the WiFi AP-user association matrix F = [f 1i ] 1×|U| Assignment, f 1i =1 means user i is associated with WiFi AP, f 1i =0 means user i is not associated with the WiFi AP, and the WiFi frequency band resources are allocated to users accessing the WiFi based on the ratio of the channel gain between the user and the WiFi;

[0103] Step 19: According to W i,j Value, calculate the average total weighted negative influence value of each user i From Wi,j The user with the largest value starts to traverse in sequence, j∈D i , calculate user i in D i The average weighted negative impact on If user i’s weight on VLC AP j has a negative impact W i,j Value greater than And VLC AP j is in the primary candidate VLC AP set Q of user i i In the case of VLCAP j, the remaining visible light band k* of VLCAP j is directly allocated to user i, and m is set to k*j =i, until all users have traversed or all VLCAPs have no available light wave bands, update the visible light band allocation matrix M = [m kj ] 3×|A| ;Calculate the cumulative channel capacity of all users to the associated VLCAP or WiFi AP to obtain the system throughput;

[0104] Step 20: Output the visible light frequency band allocation matrix M = [m kj ] 3×|A| , WiFi AP-user association matrix F=[f 1i ] 1×|U| And WiFi frequency band resource allocation and system throughput.

[0105] Combined with attachment Figure 3 ,The specific process of the flow chart of the user priority ,assessment algorithm based on user needs is as follows;

[0106] Input: Input the user set U in the indoor VLC-WiFi and the associated VLC AP set K of all users i , input the required rate of each user as r i and the basic rate r of the users in the system base Value, input VLC AP j to user i channel capacity R i,j , j∈K i , let θ i =0,i∈U;

[0107] Output: User priority factor value θ for all users i , i∈U.

[0108] Step 1: According to formula (12), calculate user i and K i The positive impact between i ;

[0109] Step 2: For K i All VLC APs in the system are associated with user set H. jMerge, then subtract user i from the merged set to generate the positive influence q i The main user set Y i ,Right now: i∈U;

[0110] Step 3: According to formula (14), calculate user i and K i The positive impact of VLC AP in the i For the main user set Y i The negative impact caused by other primary users i' Value, i∈U, i′∈Y i ;

[0111] Step 4: According to formula (15), calculate user i and K i The positive impact between i For the main user set Y i The negative weight W caused by the primary user i' i i 'value, i∈U, i′∈Y i ;

[0112] Step 5: According to formula (16), calculate user i and K i The positive impact between i The total weighted negative impact W on all users i value, i∈U;

[0113] Step 6: According to formula (17), calculate the priority factor θ of user i for selecting VLC AP based on user needs i , i∈U;

[0114] Step 7: According to the priority factor θ i Arrange users in descending order and output the priority factor θ of user selection AP based on user needs i and according to θ ii The set U, i∈U, is sorted in descending order.

[0115] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions, which should all be included in the scope of the claims of the present invention.

Claims

1. A multi-cell resource allocation method based on interference management in an indoor VLC-WiFi heterogeneous network, characterized by: The method comprises the following steps: S1: Determine the user set U, VLC access point set A, and VLC multi-color spectrum set in indoor visible light communication-wireless fidelity VLC-WiFi, and input the required rate of each user as r i , i∈U, the VLC access point AP transmission power is P vlc , the WiFi access point transmission power is P wifi , initialize the WiFi AP-user association matrix F = [f 1i ] 1×|U| And the visible light band allocation matrix M=[m kj ] 3×|A| ; Based on the VLC Lambertian radiation model, calculate the optical channel gain from each user to each VLC access point, and based on the Rayleigh fading channel model, calculate the wireless channel gain from the user to the WiFi access point; According to the Lambertian radiation model, the optical channel gain between user i in S1 and VLC AP j is calculated as The calculation formula is: In the above formula, A PD Indicates the receiving area of ​​the optical receiver, the Lambertian radiation coefficient is the half-power angle of the light-emitting diode LED, d i,j is the straight-line distance between photodetector PD i and LED j, is the emission angle of LED j, ψ is the receiving angle of PD i, ψ c is the receiver field of view angle, T(ψ) is the optical filtering gain of the receiver, and g(ψ) is the optical aggregation gain of the receiver; According to the Rayleigh fading model, the wireless channel gain between WiFi AP j and user i is calculated as The formula is: In the above formula, h r is the small-scale fading gain, which obeys the Rayleigh distribution with an average power of 2.46 dB, L(d i,j ) is the large-scale fading loss, in dB, and its expression is: In the above formula, L FS (d i,j ) is the path loss of radio waves in free space, and its value is L FS (d i,j )=20lg(f c d i,j )-147.5, in dB, shadow fading X σ is a zero-mean Gaussian random variable with a standard deviation of 3dB, f c is the center carrier frequency of the WiFi AP, which is 2.4GHz, d i,j is the communication link distance from WiFi AP j to user i, d ref is the reference distance, its value is 10m; S2: Calculate the positive impact q between user i and VLC AP j according to Shannon's formula i,j , j∈A, define q i,j The main user set is Y i,j ,q i,j The secondary user set is Z i,j , calculate the interference impact factor between each user and each VLC AP, and determine the order of selecting VLC APs in ascending order for each user according to the size of the impact factor; Among them, the specific steps of S2 are: S201: Calculate the channel capacity R from VLC AP j to user i according to Shannon's formula i,j , i∈U, j∈A, R i,j As the positive influence q between user i and VLC AP j i,j Value, that is, R i,j =q i,j ; Among them, q i,j The calculation formula is: In the above formula, is the channel bandwidth provided by VLC AP j to user i, γ is the photoelectric conversion coefficient of the PD receiving signal of user i, is the optical transmission power allocated to user i by VLC AP j, is the noise power spectral density of the VLC system; S202: Calculate the SINR value between VLC AP j and user i User i receives All VLC APs with a value greater than 1 are stored in the set K i In, K i Represents the set of VLC APs that can be associated with user i; All users greater than 1 are stored in the set H j In the example, the candidate user set of VLC AP j will not include H of user i. j All other users in the VLC AP j are considered as the primary user set Y of user i that can be associated with VLC AP j. i,j , that is: Y i,j =H j \i, calculate the positive influence q between user i and VLC AP j i,j For the main user set Y i,j The negative impact caused by the primary user i' value; Among them, VLC AP j to user i and The calculation formulas are: S203: Calculate the positive influence q between user i and VLC AP j i,j For the main user set Y i,j The negative impact of the weight caused by the main user i' value; in, The calculation formula is: In the above formula, r max is the maximum demand rate of all users in the entire system, r min is the minimum required rate of all users in the entire system, r base The basic rate requirement of the user is set to 5Mbps, r i' is the data rate requirement of user i'; S204: K i The candidate user sets of all VLC AP j's except VLC AP j are merged, and H j The associated users in the VLC AP j are obtained by obtaining the secondary user set that user i can associate with, and using Z i,j Indicates that S205: Calculate the positive influence q between user i and VLC AP j i,j For the secondary user set Z i,j Negative impact caused by secondary user i value; in, The value is calculated as: S206: Calculate the positive influence q between user i and VLC AP j i,j For the secondary user set Z i,j The negative impact of the weight caused by the secondary user i value; in, The value is calculated as: S207: Calculate the positive influence q between user i and VLC AP j i,j The total negative weight W caused to all users i,j value; Among them, W i,j The value is calculated as: S208: Calculate the interference impact factor α between user i and VLC AP j i,j value; Among them, α i,j The value is calculated as: S209: Repeat steps S201 to S208 to calculate the interference impact factor between each user and each VLC AP, and form an impact factor matrix α = [α i,j ] |U|×|A| ; S3: Construct a set of VLC APs whose SINR value to user i is greater than 1 in the system, denoted as K i , i∈U,K i represents the set of VLC APs that can be associated with user i; according to the Shannon formula, the relationship between user i and K is calculated. i The positive impact between i , construct q i The main user set Y i for: Determine the priority factor for user i to select VLC AP Repeat step S3 to generate a priority factor for each user, and sort the users in descending order according to the priority factor; The specific steps of S3 are: S301: Calculate the set K of VLC APs that user i can associate with i The positive impact q of all VLC APs on user i in i ; Among them, q i The value is calculated as: S302: For K i All VLC APs in the system are associated with user set H. j Merge, then subtract user i from the merged set to generate positive influence q i The main user set Y i ; Among them, the main user set Y of user i i The calculation formula is: S303: Calculate user i and K i The positive impact of VLC AP in the i For the main user set Y i The negative impact caused by other primary users i' value; in, The calculation formula is: S304: Calculate user i and K i The positive impact between i For the main user set Y i The negative impact of the weight caused by the main user i' value; in, The calculation formula is: S305: Calculate user i and K i The positive impact between i The total weighted negative impact W on all users i value; W i The calculation formula is: S306: Calculate the priority factor of user i in selecting the VLC AP in, The calculation method is: S307: Repeat the operations from S301 to S306 to calculate the priority factor of each user in the set U in turn, and then calculate the priority factor of each user in the set U according to the priority factor. Arrange users in descending order to generate a priority order for users to select APs; S4: Based on the interference impact factor obtained in S2 and the user priority factor obtained in S3, a multi-cell resource allocation algorithm based on interference management is executed, and the connection information and spectrum resource allocation status of the VLC AP or WiFi AP selected by all users are output; The steps of the multi-cell resource allocation algorithm based on interference management described in step S4 are: S401: Traverse the associated VLC AP j of user i in U in sequence, j∈K i If the interference factor between user i and VLC AP j is greater than the interference factor between VLC AP j and other users, then VLC AP j is removed from K i Delete from and get the candidate VLC AP set D for user i i , where other users here refer to users with a smaller priority factor than user i and located in H j Users within; S402: Traverse candidate VLC AP j of user i in sequence, j∈D i , if the interference factor α between user i and VLC AP j i,j Less than the average impact factor between VLC AP j and other user i' Then add VLC AP j to the primary candidate VLC AP set Q of user i i Here, other users refer to those with a smaller priority factor than user i and located in H j User i* in the, that is, i*∈(U i ∩H j ), U i is the set of users with a smaller priority factor than user i; S403: Repeat steps S401 and S402 to obtain a candidate VLC AP set D for each user in U i and the primary candidate VLC AP set Q i , if user i’s candidate VLC AP set D i If is an empty set, then user i is connected to the WiFi AP, i∈U; S404: According to the priority factor Select user i in descending order, and sort the candidate VLC AP set D of user i according to the interference impact factor between user i and VLC AP in descending order. i Sort them and allocate an available visible light band to the user in the order of the spectrum resources of each VLC AP, including red light band, green light band, and blue light band. If a certain VLC AP j is the main candidate VLC AP for user i, that is: VLC AP j∈Q i , the VLC AP j allocates two available visible light bands to user i until the user's required rate is met or there is no available visible light band. The available visible light band refers to the remaining visible light band of VLC AP j. If the remaining visible light band is allocated to user i without causing interference to other users, then this visible light band is the available visible light band of user i. The other users here refer to the users who have been allocated visible light bands and are located in H j For users in , if user i cannot obtain the available visible light bands of all VLC APs, user i is associated with the WiFi AP; S405: Repeat step S404 until all users are traversed; the visible light band allocation matrix M of the VLC AP is [m kj ] 3×|A| Assignment, k = 1, 2, 3, respectively represent the red light band, green light band, blue light band of VLC AP, j represents the sequence number of VLC AP, element value m kj =i represents that the visible light band k of VLC AP j is allocated to user i; for the WiFi AP-user association matrix F = [f 1i ] 1×|U| Assignment, f 1i =1 means user i is associated with WiFi AP, f 1i =0 means user i is not associated with WiFi AP; Statistics WiFi AP-user association matrix F = [f 1i ] 1×|U| The number of users with a median value of 1 allocates WiFi frequency resources to users accessing WiFi based on the ratio of the channel gain between the user and WiFi. S406: W calculated according to S207 i,j Value, calculate the average total weighted negative influence value of each user i From W i,j The user with the largest value starts to traverse in sequence, j∈D i , calculate user i in D i The average weighted negative impact on If user i’s weight on VLC AP j has a negative impact W i,j Value greater than And VLC AP j is in the primary candidate VLC AP set Q of user i i In the case of VLC AP j, the remaining visible light band k* is directly allocated to user i, and m is set k*j =i, until all users have traversed or all VLC APs have no available light bands, update the visible light band allocation matrix M = [m kj ] 3×|A| ; Calculate the cumulative channel capacity of all users to the associated VLC AP or WiFi AP to obtain the system throughput; Output the resource allocation result visible light band allocation matrix M = [m kj ] 3×|A| , WiFi AP-user association matrix F=[f 1i ] 1×|U| And WiFi frequency band resource allocation and system throughput.

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