KR101769619B1 - Apparatus and method for resource allocation in transmitter and receiver system of visible light communications - Google Patents

Abstract

The present invention proposes a method of allocating resources in consideration of the supporting capability of a visible light communication terminal in a visible light communication system supporting various band bands. To this end, the present invention provides a method for providing a visible light communication service using a multi-band with a visible light communication terminal located in a service area of a light source in a communication control device, Determining whether a resource supported by a visible light communication terminal is available; and requesting a visible light communication terminal to exchange a resource with another visible light communication terminal if there is no available resource. If the exchange of resources is permitted, the recovered resources can be allocated to the newly entered visible light communication terminal, so that the visible light communication service can be provided.

Description

[0001] APPARATUS AND METHOD FOR RESOURCE ALLOCATION IN TRANSMITTER AND RECEIVER SYSTEM OF VISIBLE LIGHT COMMUNICATIONS [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a visible light communication system, and more particularly, to an apparatus and a method for communicating visible light communication terminals having different communication bands in a light source cell region in a visible light communication system.

In recent years, as the luminous efficiency of LED (Light Emitting Diode) has improved and the price has dropped, LEDs have become commonplace in general lighting markets such as fluorescent lighting incandescent lamps as well as special lighting markets such as portable devices, displays, automobiles, have. Recently, due to depletion of radio frequency (RF) frequency band, possibility of confusion between various wireless communication technologies, increase of security requirement of communication, and the introduction of ultra high-speed ubiquitous communication environment of 4G wireless technology, With increasing interest, researches on visible light wireless communication using visible light LEDs are being conducted by various companies and research institutes.

Visible light communication, which transmits information using visible visible light, is safe, has a wide use band, and can be used freely without being regulated. Since it can see the place where the light arrives or the direction in which the light travels, It has the advantage of knowing the range accurately. Therefore, it is reliable from the viewpoint of security, and has a merit that it can be driven with low power in terms of power consumption. Therefore, visible light communication can be applied to hospitals and airplanes where the use of radio frequency (RF) is restricted, and additional information service using a display board can also be provided. Such a visible light communication system will be described with reference to FIG.

1 is a block diagram of a visible light communication system using general visible light communication (VLC). A general visible light communication system includes a light source 10 and an visible light transmission / reception module, which are composed of LEDs or LDs (Laid Diodes) and perform data transmission / reception by using visible light and at the same time perform data transmission / reception with the light source 10 And a visible light communication terminal (20). The visible light communication terminal may include a mobile terminal such as a mobile phone, a PDA, or a fixed terminal of a desktop type. In addition, visible light communication can be used more efficiently in combination with a communication system using different communication media such as wired and wireless.

In such a visible light communication system, many user services are possible by dividing the wavelength band used to support various terminals. However, in the current visible light communication system, there is no specification on the use standard for LED and LD band, and an access device (AP) as a communication control device through a LED light source supporting a single / multi band performs service management Should be. In the service area of such a light source, one or more visible light communication terminals are located, and the bands supported by the one or more visible light communication terminals may be different from each other. That is, not only a terminal supporting a single band but also a terminal supporting multiple bands coexist in the service area. For example, when a terminal supporting a single band initially allocates the band to another terminal in the communication control apparatus at the time of initial access, communication with the terminal that has initially accessed the terminal is impossible. In such a case, the problem of allocation of band resources may become an important issue.

Accordingly, the present invention provides an apparatus and method for efficiently allocating resources to one or more visible light communication terminals.

The present invention also provides an apparatus and method for enabling visible light communication even when terminals supporting a single band and multiple bands coexist in a service area of a light source.

According to another aspect of the present invention, there is provided a method for allocating resources in a resource allocation apparatus for a visible light communication system, the method comprising: receiving an initial connection from a visible light communication terminal; determining whether there is a resource to be allocated to the visible light communication terminal; The method of claim 1, further comprising the steps of: (a) collecting resources allocated from a visible light communication terminal of any one of visible light communication terminals belonging to a light source service area when there is no resource to be allocated as a result of the determination; To the connected visible light communication terminal.

According to another aspect of the present invention, there is provided a resource allocation apparatus for a visible light communication system, including: a light source; an initial connection from the visible light communication terminal through the light source; If there is no resource to be allocated as a result, after collecting resources allocated from any one of the visible light communication terminals of the visible light communication terminals belonging to the light source service area, information on the collected resources is transmitted to the initially accessed visible light communication terminal And a control unit for controlling the display unit.

According to the present invention, in a visible light communication system using multiple bands, resources are allocated to terminals belonging to a service area of a light source, and resources can be allocated to newly entering terminals when resources are allocated to newly entering terminals. There is an advantage that it can be utilized efficiently.

In addition, according to the present invention, it is possible to allocate resources to a newly entering terminal, which enables communication services for more terminals in a single service area.

1 shows a general visible light communication system,
2 is a configuration diagram of a visible light communication system according to an embodiment of the present invention,
3 is a diagram illustrating a resource allocation process according to an initial connection according to an embodiment of the present invention;
4 is an internal block diagram of a visible light communication terminal according to an embodiment of the present invention;
5 is an internal block diagram of a resource allocation apparatus according to an embodiment of the present invention;
FIG. 6 is a flowchart illustrating a resource allocation method according to an embodiment of the present invention;
7 illustrates a frame structure according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an apparatus and an operation method of the present invention will be described in detail with reference to the accompanying drawings. It will be appreciated that those skilled in the art will readily observe that certain changes in form and detail may be made therein without departing from the spirit and scope of the present invention as defined by the appended claims. To those of ordinary skill in the art. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

The present invention proposes a method of allocating resources in consideration of the supporting capability of a visible light communication terminal in a visible light communication system supporting various band bands. To this end, the present invention provides a method for providing a visible light communication service using a multi-band with a visible light communication terminal located in a service area of a light source in a communication control device, Determining whether a resource supported by a visible light communication terminal is available; and requesting a visible light communication terminal to exchange a resource with another visible light communication terminal if there is no available resource. If the exchange of resources is permitted, the recovered resources can be allocated to the newly entered visible light communication terminal, so that the visible light communication service can be provided.

Before describing the present invention, various bands supported by the visible light communication system used in the present invention will be briefly described.

In general, the total range of visible light wavelengths used in the visible light communication system is 380 to 780 nm, and up to thirteen effective wavelength bands, which can be used as wavelength channels, can exist. However, the number of wavelength bands to be divided can be changed in consideration of various factors. For example, if six wavelength bands are used, different data can be transmitted for six wavelength bands per one time slot channel.

The components of the visible light communication system capable of supporting multiple bands and their operation will now be described with reference to FIG. 2 is a configuration diagram of a visible light communication system according to an embodiment of the present invention.

2, the visible light communication system includes one or more terminals 1 to n (201, 202, 203, 204, 205 and 206), a light source 210 and a communication control device 215. Herein, it is assumed that each of the terminals 1 to n (201, 202, 203, 204, 205, and 206) operates in a time slot allocated to itself among n time slots that are located in the service area of the light source 210 . When the terminals 1 to n (201, 202, 203, 204, 205, and 206) communicate with the light sources 210 using different bands, band 1, band 2, It is assumed that communication is performed using bands 1 to 5.

Since each of the terminals 1 to n (201, 202, 203, 204, 205, and 206) performs communication with different bands, the light source 210 must communicate with each of the terminals 1 to n (201, 202, 203, 204, 205 and 206) in accordance with different bands. To this end, each of the terminals 1 to n (201, 202, 203, 204, 205, and 206) receives an initial message transmitted from the light source 210 when located in a service area of the light source 210. Then, time synchronization is performed using a C slot 230, which is a predetermined time slot included in the initial message, and an initial access is made to a light source (not shown) using a predetermined time slot and a predetermined band or a random band 210). In case of a terminal making initial connection using a random band, if the light source 210 can support multiple bands, it is possible to configure a communication link with the terminal. Thus, a communication link is formed. At this time, each of the terminals 1 to n (201, 202, 203, 204, 205, and 206) transmits band information that they can use by including them in the initial connection.

Then, each of the terminals 1 to n (201, 202, 203, 204, 205, and 206) receives the resource allocation information including the time slot and the band allocated to itself through the light source 210, and sets the allocated band. Accordingly, each of the terminals 1 to n (201, 202, 203, 204, 205, and 206) transmits and receives data according to visible light communication using the band set in the time slot allocated to itself.

For example, if band 1 is a predetermined band for initial connection, the terminal that intends to attempt initial connection transmits band information that can be used by band 1 to light source 210. Then, the light source 210 allocates communication resources by allocating usable time slots and bands to the terminal using the band information.

Meanwhile, after establishing a communication link, the light source 210 exchanges available band information and available time slot information with each of the terminals 1 to n (201, 202, 203, 204, 205 and 206), and allocates resources to the terminals 1 to n (201, 202, 203, 204, 205 and 206). Since each of the terminals 1 to n (201, 202, 203, 204, 205, and 206) has different bands, the light source 210 communicates with each of the terminals 1 to n (201, 202, 203, 204, 205, and 206) according to different bands.

Accordingly, the light source 210 communicates with each of the terminals 1 to n (201, 202, 203, 204, 205, and 206) using the time slots and bands assigned to the terminals 1 to n (201, 202, 203, 204, 205 and 206) by allocating communication band resources and time slots. This resource allocation is made at the time of initial connection. If a plurality of terminals 1 to n (201, 202, 203, 204, 205, and 206) communicate with the light sources 210 with different bands, communication between the terminals 1 to n (201, 202, 203, 204, 205, 206) and the light sources 210 is possible in the same time slot.

Here, in FIG. 2, a case is shown in which one time slot TS1 (Time Slot) is allocated to the terminal 1 (201), and one TS2 to TSn is assigned to each terminal 2 to n (202,203,204,205,206) But is not limited thereto. It is needless to say that each of the terminals 1 to n (201, 202, 203, 204, 205, and 206) may have a frame structure allocated to one and the same time slot if they have different bands. Therefore, according to the embodiment of the present invention, a combination between a band that can be supported by a terminal and a time slot to be allocated may vary.

An example of a frame structure to which such a resource allocation is applied is as indicated by reference numeral 220. The frame structure in FIG. 2 includes a C slot 230, control information 235, an uplink interval 240, and a downlink interval 250, which are time slots used for initial connection. In this frame structure, the resource allocation information may be transmitted / received in the control information 235 period.

The light source 210 transmits the transmission data received from the communication control device 200 to each of the terminals 1 to n (201, 202, 203, 204, 205, and 206) located in its service area. The light source 210 transmits the reception data received from each of the terminals 1 to n (201, 202, 203, 204, 205, and 206) to the communication control device 200.

Thereafter, when the terminal n + 1 207 attempts initial connection, the light source 210 determines whether there is a time slot available for allocating resources to the terminal n + 1 (207). If there is no time slot to allocate, the terminal n + 1 207 determines whether a usable band is used among the existing terminals 1 to n (201, 202, 203, 204, 205, and 206). If there is no band to allocate because it is already in use, communication resources can not be allocated, and communication with the terminal n + 1 (207) becomes impossible. In order to prevent this, the light source 210 reallocates bands assigned to existing terminals 1 to n (201, 202, 203, 204, 205, and 206) to different bands or reallocates time slots. Or reassign both the band and the time slot. To this end, the light source 210 requests resource exchange of a band and / or a time slot to any one of the existing terminals 1 to n (201, 202, 203, 204, 205, and 206) Quot; is allocated to the resource. A detailed description thereof will be described later.

The communication control unit 215 processes the data to be transmitted to the terminals 1 to n (201, 202, 203, 204, 205 and 206) according to visible light communication and transmits the processed data to the terminals 1 to n (201, 202, 203, 204, 205 and 206) through the light source 210, 202,203, 204,205, 206). < / RTI >

This communication control device 215 manages the light source 210, and in particular manages time slots and bands in accordance with embodiments of the present invention. In the following description, a device including the light source 210 and the communication control device 215 is referred to as a resource allocation device, and according to the embodiment of the present invention, 206, 203, 204, 205, and 206, and a band to be used for the specific time slot. Such resource allocation apparatuses include an access point, a base station, and the like.

Meanwhile, FIG. 3 is referred to in order to explain the initial connection process in detail. FIG. 3 is a diagram illustrating a resource allocation process according to an initial connection according to an embodiment of the present invention, illustrating a case where the first UE 201 initially accesses. 3 illustrates a process of allocating a resource between the terminal 201 and the light source 210. The communication controller 215 connected to the light source 210 performs control for resource allocation. The light source 210 will be mainly described.

Referring to FIG. 3, in step 301, the terminal 1 (201) attempts initial connection to the light source 210 using an initial access band. Accordingly, a communication link with the light source 210 is established. Here, for initial connection, the first terminal 201 uses an initial connection time slot like the C slot 230 of FIG. In addition, a predetermined band can be used as the initial connection band. Alternatively, the light source 210 may be configured to support multiple bands so that the initial connection band of the terminal 1 (201) is not limited. If the light source 210 supports multiple bands, the light source 210 can use any band even if the first terminal 201 tries to make an initial connection in an initial connection time slot such as a C slot using an arbitrary band Therefore, initial connection of the terminal 1 (201) is possible. That is, since the light source 210 can support multiple bands, all terminals attempting initial connection regardless of bands used in the terminal can be initially connected.

After the communication link according to the initial connection is established, the light source 210 allocates a time slot to the first terminal 201 in step 305 using the initial access band. The allocated time slot information is included in the control information section 235 of FIG. 2 and is transmitted to the terminal 1 (201). Accordingly, visible light communication is performed between the light source 210 and the terminal 1 (201) by transmitting and receiving data in the allocated time slot as in step 310.

In step 315, the light source 210 may transmit information on multiple bands available for the light source 210 in the allocated time slots using the initial access band. This process is performed to change the initial access band to the multiband that the light source 210 can support, or to leave the initial access band for other terminals to attempt initial access. That is, the initial access band changes the band so that it can be used only during the initial connection. The multiband information used by the light source 210 can be received from the first terminal 201 as in step 315. Alternatively, the light source 210 can also receive multiband information available in the first terminal 201 It is of course possible to implement. The transmission process of the multi-band information may be bidirectional or may be performed in any one direction.

Accordingly, in step 325, the terminal 1 (201) transmits a response to the multi-band information to the light source 210. For this response, the terminal 1 (201) may compare the multibands of the light source 210 with the available bands, and then transmit the common band as a result of the comparison. Alternatively, the terminal 1 (201) may select a usable band among multiple bands of the light source 210 and transmit the selected band as a response. If the multi-band information of the first terminal 201 is received from the light source 210, a response is transmitted to the first terminal 201 in step 330, and the operation for the response is the same as in the first terminal 201. [

Upon receiving the response, the light source 210 confirms the change of the multiple bands in step 335, and the process of changing the multiple bands is completed through the confirmation. Likewise, if the light source 210 transmits a response in step 330, the terminal 1 201 confirms the change of the multiple bands in step 340. Accordingly, in step 345, data transmission / reception using multi-bands is performed in the time slot allocated to the first mobile station 201. In this manner, steps 315, 325, and 335 and steps 320, 330, and 340 are different from each other, but show the same operation, and visible light communication is possible with only one of the operations. In step 350, the terminal 1 (201) transmits an Ack / Nack signal to the light source 210 for confirming whether data is transmitted or received. If the Nack signal is transmitted, the light source 210 retransmits the data using the multiple bands in the allocated time slot in step 355.

In the visible light communication system configured as described above, an example of the visible light communication terminal is shown in Fig. 4 is a diagram showing a configuration of a visible light communication terminal.

4, the visible light communication terminal 400 includes a first memory 411, a controller 412, a first encoder 413, a first modulator 414, a first transmission driver 415, an LED A first demodulator 416, a first demodulator 416, a first demodulator 416, a first demodulator 416, and a photodiode 421 .

The control unit 412 processes data for transmitting and receiving data according to visible light communication and controls the first encoder 413, the first decoder 48 and the selection unit 417, and controls the overall operation of the visible light communication terminal 400 .

If there is a request to change or release a resource allocated from the resource allocation device in the allocated time slot, the controller 412 generates and transmits a response to permit or reject the resource. Here, the change request for the allocated resource may be a change request for the band or time slot being used by the visible light communication terminal 400, or a change request for both the band and the time slot. For example, when the visible light communication terminal 400 capable of using the bands 1 to 6 is using the band 1, the resource allocation device may select one of the bands 2 to 6 to request the band 1 to change to the selected band have. Then, the control unit 412 transmits a response to permit or reject the band change to the selected band.

Alternatively, when the resource allocation apparatus requests release of the band 1 being used by the visible light communication terminal 400, the control unit 412 may transmit the service interruption through the band 1 as a response. Selection of service interruption can be made by the user of the visible light communication terminal 400.

The first encoder 413 encodes the transmission data input from the controller 412 and outputs the encoded data to the first modulator 414. The first modulator 414 modulates the input transmission data and outputs it to the first transmission driver 415.

The first transmission driver 415 is an LED 416 driver that optically modulates the transmission data input from the first modulation unit 414 and drives the LED 416 according to the band selected by the selection unit 417 .

The LED 416 is a light emitting element provided for transmitting the transmission data to the external device using the optical signal, and is driven by the first transmission driver 415. The types of light emitting devices that the visible light communication terminal can have are various, and each light emitting device supports different bands depending on its characteristics. Therefore, the type of band that can be used is determined according to the wavelength characteristic of the light emitting device provided in the visible light communication terminal.

The photodiode 421 is a photosensitive element that senses an optical signal transmitted from an external device. The photodiode 421 receives an optical signal including received data from the light source 210, converts the optical signal into an electrical signal, Output.

The first reception driver 420 adjusts the band detection of the photodiode 421 according to the band selected by the selection unit 117 as a driver for the photodiode 421. The first reception driver 420 outputs the electric signal input from the photodiode 421 to the first demodulation unit 419.

The first demodulation unit 419 demodulates the electric signal input from the first reception driver 420 into data according to the optical wireless communication system, and outputs the reception data to the first decoder 418.

The first decoder 418 decodes the received data and outputs the decoded data to the control unit 412. The control unit 412 processes the received data input from the first decoder 418. [

The first memory 411 stores a program for processing and controlling the control unit 412, reference data, various updatable storage data, and the like, and stores information on time slots and bands allocated according to the embodiment of the present invention .

Hereinafter, a configuration and operation of a resource allocation apparatus according to an embodiment of the present invention will be described with reference to FIG. 5 is an internal block diagram of a resource allocation apparatus according to an embodiment of the present invention.

The resource allocation device includes a communication control unit 215 and a light source 210 connected thereto. Specifically, the communication control unit 215 includes a second memory 551, a control unit 552, a second encoder 553, A second demodulation unit 554, a second decoder 555, a second demodulation unit 556, and a first input / output stage 559.

In addition, the light source 210 may include one wavelength tunable LED or a plurality of LEDs and a plurality of photodiodes. These LEDs are wavelength tunable or wavelength selectable or wavelength fixed LEDs, for example, each LED may include a white light LED and a tunable (or optional) filter. Likewise, each photodiode may also include a tunable (or selective) filter. The light source 210 may include a second input / output unit, a selection control unit, a second transmission driver, an LED, a second reception driver, and a photodiode, similarly to the configuration of the visible light communication terminal.

Among them, the second encoder 553, the second modulator 554, the second decoder 555, the second demodulator 556, the second transmission driver, the second reception driver, the LED, the photodiode, Operates in a similar manner to each component of the visible light communication terminal and plays a similar role, so that a detailed description thereof will be omitted.

The second memory 551 stores a program for processing and controlling the control unit 552, reference data, various updatable storage data, and the like. In accordance with the embodiment of the present invention, Information on allocated time slots and bands, and the like.

The communication control unit 215 transmits and receives data with the light source 210 through the first input output 559.

The control unit 552 controls the overall operation of the resource allocation apparatus and controls all operations required to allocate and manage time slots and bands for each terminal belonging to the service area of the light source 210 according to an embodiment of the present invention. . More specifically, the control unit 552 searches for a resource that can be allocated when there is a terminal attempting initial access to the service area of the light source 210. [ If there is no allocatable resource, that is, no time slot and no band, the controller 552 determines a terminal for collecting allocated resources from existing terminals based on the resource allocation state stored in the second memory 551. [

A method for allocating resources to an attempted terminal by changing resources allocated to existing terminals is as follows. More specifically, the control unit 552 selects a terminal capable of using multiple bands from existing terminals, changes the band in use in the selected terminal to another band, or requests release of a band in use. This method is a method of changing only the band without changing the time slot.

Also, if several terminals have different bands, it is possible to communicate with various terminals in the same time slot. In this case, the control unit 552 selects a terminal capable of using multiple bands from existing terminals and transmits a time slot allocated to the selected terminal to a time slot allocated to the terminal using a band that is not overlapped with the band currently used by the selected terminal . This method is a method of changing only the time slot.

In addition, the control unit 552 requests to change the time slot allocated to the selected terminal to the time slot allocated to the other terminal, and changes the band being used by the selected terminal to a band that is not overlapped with the band currently used by the other terminal do. This method is a method of changing both the time slot and the band.

As described above, the control unit 552 determines whether to collect only the allocated bands, only the time slots, or both the bands and time slots based on the stored resource allocation status. According to the determination result, the control unit 552 requests the change of the resource allocated to the determined mobile station or requests release of the resource. Then, the control unit 552 allocates the resources recovered from the allowed terminal to the terminal attempting the initial connection.

Referring to FIG. 6, the operation of the visible light communication terminal 400 and the resource allocation device configured as described above will be described. 6 is a flowchart illustrating a resource allocation method according to an embodiment of the present invention. In the following description, FIG. 2 will be exemplified and a case where band 1 is used as an initial connection band will be described as an example.

Referring to FIG. 6, the resource allocation apparatus 600 establishes an initial connection and a communication link with each of the terminals 1 to n (201, 202, 203, 204, 205, and 206) in the service area of the light source 210. Then, the resource allocation apparatus 600 allocates time slots to each of the terminals 1 to n (201, 202, 203, 204, 205, and 206) using the initial access band as in steps 603 to 607 using the set link. In step 609, the resource allocation apparatus 600 exchanges multi-band information with each of the terminals 1 to n (201, 202, 203, 204, 205, 206) in the time slots allocated to the terminals 1 to n (201, 202, 203, 204, 205, 206) And transmits and receives data using the allocated time slots. The resource allocation process according to the initial connection in each of the terminals 1 to n (201, 202, 203, 204, 205, and 206) has been described in detail with reference to FIG. 3, and therefore, the operation in FIG. 3 will be referred to.

Here, a frame structure as shown in FIG. 7 may be used for transmission of multi-band information. The resource allocation apparatus 600 may provide band information to each terminal using an initial access band in a time slot allocated to each terminal or may be provided from each terminal. In order to exchange multi-band information, a first multi-band information field (Src_multi_info) 710 and a second multi-band information field (Des_multi_info) 715 of the frame structure of FIG. 7 can be used. The first multi-band information field (Src_multi_info) 710 stores available multi-band information in the resource allocation apparatus 600 and the second multi-band information field (Des_multi_info) 715 stores multi- . Also, the time slot information field (S_info) 700 of FIG. 7 is used for time slot allocation.

As described above, when resources such as time slots and bands are allocated to each of the terminals 1 to n (201, 202, 203, 204, 205, and 206), data transmission / reception using the allocated resources is performed. In the meantime, the terminal n + 1 (207) can attempt initial connection using the initial access band in the service area of the light source 210. At this time, the terminal n + 1 207 attempts initial connection using the initial access band in the C slot for the initial connection as in the other terminals. In this case, after receiving the initial access in step 611, the resource allocation apparatus 600 searches the terminal n + 1 (207) for the available time slots and bands in step 613.

Here, the resource allocation apparatus 600 may separately exchange band information using the frame structure of FIG. 7, as in step 609, with respect to the band information used by the terminal n + 1 (207). Alternatively, the terminal n + 1 207 may transmit the usable band information using the frame structure of FIG. 7 at the initial access in step 611. [

Therefore, the resource allocation apparatus 600 can search the allocated resources based on the available band information in the terminal n + 1 (207) included in the initial connection or the band information acquired through exchange of the multi-band information. Since the information on the band to be transmitted in the initial connection is provided to the resource allocation apparatus 600, it is provided in a second multi-band information field (Des_multi_info) 715 of the frame structure of FIG. For example, when the available band in the terminal n + 1 (207) is band 1, only information on the band 1 is set in the second multi-band information field (Des_multi_info) 715 and transmitted. If the bits are mapped according to the band combination in the first multi-band information field (Src_multi_info) 710 and the second multi-band information field (Des_multi_info) 715 and using the bits mapped corresponding to the available bands, Information exchange is possible.

The procedure for searching for time slots and bands that can be allocated to the terminal n + 1 (207) in step 613 is as follows. Specifically, the resource allocation apparatus 600 searches whether a band available in the terminal n + 1 (207), for example, band 1, is used in another time slot. If there is no allocatable time slot and band 1 is also occupied by other terminals in each time slot, it is searched. If no allocatable time slots and bands are found, the resource allocation apparatus 600 determines a terminal for changing an existing allocated resource in step 615. [

The resource allocation apparatus 600 selects one of existing terminals using multiple bands including band 1 to change resources allocated to existing terminals. Then, the resource allocation apparatus 600 performs an operation of redistributing the recovered resources by changing the band 1 to another band or limiting the service to the band 1 for the selected terminal. By redistributing the recovered resources, it is possible to communicate with the terminal n + 1 207 that has attempted a new connection.

Assuming that the terminal 2 202 is a terminal capable of communicating using bands 1 to 6 and the terminal n 206 is a terminal capable of communicating using bands 1 to 5 as shown in FIG. 2, the resource allocation apparatus 600 allocates resources 2, and n (202, 206). In this case, the resource allocation apparatus 600 may request the change of the allocated resource to the terminal that can use the band of the largest number of bands and / or the terminal that uses the band that does not overlap with the terminal n + 1 207 among the multiple bands . 2, since the terminal 2 202 is the terminal that can use the most kinds of bands, the resource allocation apparatus 600 can request the terminal 2 202 to request allocation of the allocated resources or cancel the allocated resources as in step 617 .

If the terminal 2 202 is using some of the bands 2 to 6, including band 1, or all of the bands 1 to 6, the request for change of the allocated resource uses the used band 1 among the bands 2 to 6 It means a change request to a non-busy band. Also, the release request of the allocated resource means a service stop request using the band 1. At this time, since the time slot allocated to the terminal 2 (202) is TS2, the change request is transmitted in the time slot TS2. This method of changing the allocated resources corresponds to a method of changing only the band without changing the time slot.

If the terminal 2 202 uses some of the bands 1 to 6 but there is no overlapping band with the terminal n 206 using some of the bands 1 to 5, To change it. In this case, the resource allocation apparatus 600 requests the terminal 2 (202) to change the TS2 to the time slot TSn assigned to the terminal n (206). In this way, when requesting the change of the allocated resource, it can be requested to change only the time slot.

If the terminal 2 202 is using some of the bands 2 to 6 including the band 1, it requests the terminal n 206 to change the time slot allocated to the terminal n 206, n 206 may request a change to a band that does not overlap with the band in use. That is, the resource allocation apparatus 600 can request a change of both the time slot and the band.

In response to the request, the terminal 2 (202) transmits a response to the allocation resource change or a release response to the resource allocation apparatus 600. In this way, the resource allocation apparatus 600 recovers resources allocated from the terminal 2 (202). Accordingly, in step 625, the resource allocation apparatus 600 transmits the allocated resource information to allocate resources recovered in step 625 to the terminal n + 1 207. [ In step 627, the terminal n + 1 207 transmits an acknowledgment to the allocated resource, and in step 629, data transmission / reception is performed between the resource allocation apparatus 600 and the terminal n + 1 207 using the allocated resources .

For example, if time slot TS2 and band 1 are retrieved from terminal 2 202, time slot TS2 and band 1 are allocated to terminal n + 1 207. [ The time slot information and the band information are transmitted to the terminal n + 1 207 via the control information 235. Accordingly, the terminal n + 1 207 exchanges data with the resource allocation apparatus 600 using the band 1 in the allocated time slot TS2.

As described above, according to the present invention, when a band available in terminals belonging to a light source service area is varied in a resource allocation device, a serviceable resource is allocated among them, and if there is a terminal that has attempted a new connection, Compare available resources with available resources. If there is no allocatable resource, it is checked whether the terminal capable of communicating using the resources other than the resource to be allocated to the attempted terminal exists in the existing terminals. Then, after attempting to request a change of resources allocated to the terminal searched for, and receiving a response to allow the resource to be allocated to the terminal attempting to access the searched resource.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. For example, in the above-described embodiment, it is assumed that a resource is allocated in the resource allocation device. However, resources may be allocated in the communication control device or the light source. Therefore, the scope of the present invention should not be limited by the described embodiments but should be determined by the equivalents of the claims and the claims.

Claims (18)

A method for resource allocation in a resource allocation apparatus of a visible light communication system,
Determining whether there is a resource to be allocated to the visible light communication terminal when the visible light communication terminal attempts initial connection;
Requesting a visible light communication terminal of any one of the visible light communication terminals belonging to the light source service area to change the allocated resources when there is no resource to be allocated as a result of the determination;
And transmitting the information on the resources recovered from the one of the visible light communication terminals to the visible light communication terminal attempting the initial connection when receiving the response to the request from the one of the visible light communication terminals. Method for allocation.
The method of claim 1,
A time slot, and a band.
delete The method of claim 1, wherein the request for changing the allocated resource comprises:
And requesting the visible light communication terminal to use the band that does not overlap with the available band of the initially accessed visible light communication terminal while supporting the largest band among the other visible light communication terminals. Lt; / RTI >
3. The method of claim 2, wherein the step of recovering the allocated resource comprises:
And requesting a change of at least one of a time slot and a band allocated to any one of the visible light communication terminals.
The method of claim 1, wherein the step of determining whether there is a resource to be allocated comprises:
And determining whether there is a band to be allocated based on available band information of the initially connected visible light communication terminal.
The method of claim 1, wherein the step of determining whether there is a resource to be allocated comprises:
Exchanging multi-band information with the initially accessed visible light communication terminal;
Acquiring available band information of the initially accessed visible light communication terminal through exchange of the multiband information;
And determining whether there is a band to be allocated based on the obtained available band information.
2. The method of claim 1,
And the control information is transmitted to the initially-connected visible light communication terminal using the control information.
The method according to claim 1,
And transmitting and receiving data with the initially accessed visible light communication terminal using an allocated band included in the recovered resource in an allocated time slot included in the recovered resource.
A resource allocation apparatus for a visible light communication system,
A light source,
Determining whether there is a resource to be allocated to the visible light communication terminal when the visible light communication terminal attempts initial connection through the light source; and if it is determined that there is no resource to be allocated to the visible light communication terminal, The method comprising the steps of: requesting a visible light communication terminal to change the allocated resources; receiving information on resources recovered from the one of the visible light communication terminals when receiving a response to the request from the one of the visible light communication terminals; And a control unit for transmitting the resource to the communication terminal.
11. The method of claim 10,
A time slot, and a band.
delete 11. The apparatus according to claim 10,
And requests a visible light communication terminal using a band that does not overlap with an available band of the initially accessed visible light communication terminal while supporting the largest band among the other visible light communication terminals, .
11. The apparatus according to claim 10,
And requests a change of at least one of a time slot and a band assigned to any one of the visible light communication terminals.
11. The apparatus according to claim 10,
And determines whether there is a band to be allocated based on the available band information of the initially connected visible light communication terminal.
11. The apparatus according to claim 10,
Exchanges multiband information with the initially connected visible light communication terminal, acquires available band information of the initially connected visible light communication terminal through exchange of the multiband information, and allocates the available band information based on the obtained available band information And judges whether or not there is a band.
11. The method of claim 10,
And is transmitted to the initially connected visible light communication terminal using the control information.
11. The apparatus according to claim 10,
And transmits and receives data with the initially accessed visible light communication terminal using an allocation band included in the recovered resource in an allocated time slot included in the recovered resource.

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