KR20120011361A - Apparatus and method for resource allocation in transmitter and receiver system of visible light communications - Google Patents

Abstract

PURPOSE: A device for allocating resources in a visible ray communication system and a method thereof are provided to efficiently allocate resources to at least one visible ray communication terminal. CONSTITUTION: A controller(552) receives an initial access request from a visible ray communication terminal through a light source. The controller determines whether there are resources to be allocated to the visible ray communication terminal. When there are not resources to be allocated to the visible ray communication terminal, the controller collects allocated resources from a visible ray communication terminal which belongs to a light source service area. The controller transmits the information for the collected resources to the initially accessed visible ray communication terminal.

Description

APPARATUS AND METHOD FOR RESOURCE ALLOCATION IN TRANSMITTER AND RECEIVER SYSTEM OF VISIBLE LIGHT COMMUNICATIONS

The present invention relates to a visible light communication system, and more particularly, to an apparatus and method for communicating a visible light communication terminal having a different communication band in a visible light communication system in a light source cell region.

Recently, as the luminous efficiency of LED (Light Emitting Diode) is improved and the price is lowered, LED is becoming popular in general lighting market such as fluorescent incandescent lamp as well as special lighting market such as mobile device, display, automobile, traffic light, billboard. have. Recently, due to the depletion of RF (Radio Frequency) band frequency, the possibility of crosstalk between various wireless communication technologies, the increased demand for security of communication, and the arrival of ultra-high ubiquitous communication environment of 4G wireless technology, With increasing interest, research on visible light wireless communication using visible light LED is being conducted in various companies and research institutes.

Visible light communication, which transmits information using visible visible light, is safe, and because it can be used freely without restriction, it can see where the light arrives and where it is going. The advantage is that you know the exact range. Therefore, it is reliable in terms of security and has the advantage of being able to run at low power in terms of power consumption. Therefore, visible light communication can be applied to hospitals and airplanes in which RF (Radio Frequency) use is limited, and additional information services using an electronic signboard can be provided. This visible light communication system will be described with reference to FIG. 1.

1 is a configuration 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 a visible light transmit / receive module that are configured as LEDs or LDs (Layer Diodes) to perform data transmission and reception using visible light at the same time, and perform data transmission and reception with the light source 10. It is configured to include a visible light communication terminal 20. The visible light communication terminal may include a mobile terminal such as a mobile phone or a PDA or a fixed terminal in the form of a desktop. In addition, visible light communication can be used more efficiently in combination with communication systems using other communication media, wired and wireless.

In such a visible light communication system, many user services are possible by dividing and using a wavelength band used to support various terminals. However, in the current visible light communication system, there is no specification for the use of LEDs and LD bands. Therefore, an access point (AP), which is a communication control device, manages service management through an LED light source supporting single / multi band. Should be. One or more visible light communication terminals are located in the service area of the light source, 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 may 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 device during initial access, communication with the initial accessed terminal becomes impossible. In this case, the issue of allocation of band resources may be 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 a terminal supporting single band and multiple bands coexist in a service area of a light source.

According to an aspect of the present invention, there is provided a method for allocating resources in a resource allocation apparatus of a visible light communication system, the method comprising: receiving an initial connection from a visible light communication terminal and determining whether there is a resource to be allocated to the visible light communication terminal. And recovering an allocated resource from any one visible light communication terminal among other visible light communication terminals belonging to a light source service area when there is no resource to allocate, and initializing information on the recovered resource. And transmitting the connected visible light communication terminal.

In addition, the present invention, in the resource allocation apparatus of the visible light communication system, receiving an initial connection from the visible light communication terminal through one light source and the light source, and determines whether there is a resource to be allocated to the visible light communication terminal, As a result, when there is no resource to be allocated, the allocated resource is recovered from one visible light communication terminal among other visible light communication terminals belonging to a light source service area, and then information about the recovered resource is transmitted to the initially connected visible light communication terminal. It characterized in that it comprises a control unit.

According to the present invention, when a resource allocation is needed for a newly entered terminal after allocating resources to terminals belonging to a service area of a light source in a visible light communication system using multiple bands, resources may be allocated to newly entered terminals. There is an advantage that can be utilized efficiently.

In addition, according to the present invention, it is possible to allocate resources to the newly entered terminal has the advantage that the communication service for more terminals in one service area.

1 is a view showing a general visible light communication system,
2 is a block 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 initial access 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 a block diagram illustrating an internal configuration of a resource allocation apparatus according to an embodiment of the present invention;
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. In the following description, specific matters such as specific elements are shown, which are provided to help a more general understanding of the present invention. It is self-evident to those of ordinary knowledge in Esau. 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 for allocating resources in consideration of the support 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 process for providing a visible light communication service using a multi-band and the visible light communication terminals located in the service area of the light source in the communication control device, and if there is a new visible light communication terminal entered into the service area, Determining whether a resource supported by one visible light communication terminal is available, and requesting a resource exchange to any one visible light communication terminal of the other visible light communication terminals if there is no available resource. If the resource exchange is allowed, the newly entered visible light communication terminal can allocate the recovered resource to provide the visible light communication service.

Prior to 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 wavelength of visible light used in a visible light communication system is 380 to 780 nm, and there may be up to 13 effective wavelength bands that can be used as wavelength channels. 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.

As described above, each component of the visible light communication system capable of supporting the multi band and its operation will be described with reference to FIG. 2. 2 is a block diagram of a visible light communication system according to an exemplary embodiment of the present invention.

2, the visible light communication system includes one or more terminals 1 to n 201, 202, 203, 204, 205, 206, a light source 210, and a communication control device 215. Here, it is assumed that each of the terminals 1 to n (201, 202, 203, 204, 205, 206) is located in the service area of the light source 210, and each of the terminals 1 to n (201, 202, 203, 204, 205, 206) operates in a time slot assigned to itself among n timeslots. . In addition, when the terminals 1 to n (201, 202, 203, 204, 205, 206) communicate with the light source 210 by using different bands, the terminal 1 201 is band 1, the terminal 2 202 is band 1-6, the terminal n 206 Assumes communication using bands 1-5.

As described above, since the terminals 1 to n 201, 202, 203, 204, 205, and 206 communicate with each other with different bands, the light source 210 must communicate with each terminal 1 to n (201, 202, 203, 204, 205, 206) according to different bands. To this end, each terminal 1 to n (201, 202, 203, 204, 205, 206) is located in the service area of the light source 210, and receives an initial message transmitted from the light source 210. Then, time synchronization is performed using the C slot 230, which is a predetermined time slot included in the initial message, and initial access is performed using the predetermined time slot, a predetermined band, or a random band. 210). If the terminal is initially connected using a random band, if the light source 210 can support multiple bands, it is possible to configure a communication link with the terminal. This creates a communication link. At this time, each terminal 1 to n (201, 202, 203, 204, 205, 206) transmits the band information that can be used in the initial connection.

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

For example, when band 1 is a predetermined band for initial access, the terminal that attempts initial access transmits band information available to the light source 210 using band 1. Then, the light source 210 allocates a communication resource by allocating an available time slot and band to the terminal using the band information.

Meanwhile, the light source 210 exchanges usable band information and communication time slot information with each terminal 1 to n (201, 202, 203, 204, 205, 206) after establishing a communication link and allocates resources to each terminal 1 to n (201, 202, 203, 204, 205, 206). This is because 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, by allocating a communicable band resource and a time slot, the light source 210 communicates with each of the terminals 1 to n (201, 202, 203, 204, 205, and 206) using time slots and bands allocated to the terminals 1 to n (201, 202, 203, 204, 205 and 206). This resource allocation occurs at initial connection. If several terminals 1 to n 201, 202, 203, 204, 205, 206 have different bands to communicate with the light source 210, communication between the various terminals 1 to n 201, 202, 203, 204, 205, 206 and the light source 210 is possible in the same time slot.

Here, although FIG. 2 illustrates a case in which TS2 to TSn is allocated to each of terminals 2 to n (202, 203, 204, 205, and 206) such as a time slot TS1 (Time Slot) is allocated to the terminal 1 201, the time slot allocation method is It is not limited to this. Each terminal 1 to n (201, 202, 203, 204, 205, 206) may have a frame structure allocated to one same time slot when having different bands. Therefore, according to an embodiment of the present invention, the combination between the supportable band of the terminal and the time slot to be allocated may vary.

An example of the frame structure to which such 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 section 240, and a downlink section 250, which are time slots used for initial access. In this frame structure, resource allocation information may be transmitted / received in the control information 235 section.

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

Subsequently, when the terminal n + 1 207 attempts initial access, the light source 210 determines whether there is a time slot for allocating resources to the terminal n + 1 207. If there is no time slot to allocate, it is determined whether the band available for the terminal n + 1 207 is used among the existing terminals 1 to n (201, 202, 203, 204, 205, 206). If there is no band to be allocated because it is already in use, communication resources cannot be allocated and communication with the terminal n + 1 207 may be impossible. In order to prevent this, in the present invention, the light source 210 reallocates a band allocated to the existing terminals 1 to n 201, 202, 203, 204, 205, and 206 to another band or reallocates a time slot. Alternatively, both band and time slots may be reallocated. To this end, the light source 210 requests a 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, 206), and then newly enters the terminal n + 1 (207). Will allocate the recovered resources. Detailed description thereof will be described later.

The communication control device 215 processes the data to be transmitted with the terminals 1 to n (201, 202, 203, 204, 205, 206) and transmits the data to the terminals 1 to n (201, 202, 203, 204, 205, 206) through the light source 210, and transmits the terminal 1 to the terminal 1 according to the visible light communication. Processes data received via ˜n (201, 202, 203, 204, 205, 206).

The communication control device 215 manages the light source 210, and in particular, manages time slots and bands according to embodiments of the 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, the resource allocation device according to an embodiment of the present invention through each light source 210 each terminal 1 ~ n It serves to allocate a specific time slot to be used at 201,202,203,204,205,206 and a band to be used for that specific time slot. Such resource allocation apparatuses include an access point and a base station.

Meanwhile, to describe the initial access procedure in detail, reference is made to FIG. 3. 3 is a diagram illustrating a resource allocation process according to an initial connection according to an embodiment of the present invention, and illustrates a case in which the terminal 1 201 is initially connected. In addition, although FIG. 3 illustrates a resource allocation process between the terminal 201 and the light source 210, a control for resource allocation is performed by the communication control device 215 connected to the light source 210. For the sake of brevity, the light source 210 is mainly described.

Referring to FIG. 3, the terminal 1 201 attempts initial access to the light source 210 using an initial access band in step 301. This establishes a communication link with the light source 210. Here, for the initial access, the terminal 1 201 uses a time slot for initial access attempt as shown in the C slot 230 of FIG. 2. In addition, a predetermined band may be used as the initial access band. Alternatively, the light source 210 may be configured to support multiple bands so that the initial access 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 terminal 1 201 attempts initial access in an initial access time slot such as a C slot using an arbitrary band. Therefore, the initial connection of the terminal 1 (201) is possible. That is, since the light source 210 may support multiple bands, all terminals attempting initial access may be initially connected regardless of the band used by the terminal.

After the communication link according to the initial connection is established, the light source 210 allocates a time slot to the terminal 1 201 using an initial access band in step 305. The allocated time slot information is included in the control information section 235 of FIG. 2 and 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.

Subsequently, the light source 210 may transmit information on multiple bands that can be used by the light source 210 in a time slot allocated using the initial access band in step 315. This process is to change the initial access band to the multiple bands that the light source 210 can support or to leave the initial access band for another terminal to attempt initial access. That is, the initial access band is to change the band so that it can be used only during the initial access. Although the multi-band information used by the light source 210 may be provided in the terminal 1 201 as in step 315, the light source 210 may also be provided with the multi-band information available in the terminal 1 201. Of course it can be implemented. The transmission process of the multi-band information may be made in both directions, or may be made in only 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 multiple bands of the light source 210 with the bands available to the user, and then transmit a common band as a response as a result of the comparison. Alternatively, the terminal 1 201 may select a band that can be used among multiple bands of the light source 210 and transmit the selected band as a response. If the light source 210 receives the multi-band information of the terminal 1 201, the response is transmitted to the terminal 1 201 in step 330, and the operation for the response is the same as that of the terminal 1 201.

When receiving the response, the light source 210 confirms the change of the multi band in step 335 and then completes the process of changing the multi band through such confirmation. Likewise, when the light source 210 transmits the response in step 330, the terminal 1 201 confirms the change of the multi band in step 340. Accordingly, in step 345, data transmission and reception using multiple bands is performed in the time slot allocated to the terminal 1 201. As described above, the subjects in steps 315, 325, and 335 and the steps 320, 330, and 340 are different, but represent the same operation, and visible light communication is possible by only one operation. In step 350, the terminal 1 201 transmits an Ack / Nack signal to the light source 210 to confirm whether data is transmitted or received. If the Nack signal is transmitted, in step 355, the light source 210 retransmits data using multiple bands in the allocated time slot.

In the visible light communication system configured as described above, an example of the visible light communication terminal is illustrated in FIG. 4. 4 is a diagram illustrating a configuration of a visible light communication terminal.

Referring to FIG. 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, and an LED ( Light Emitting Diode (416), Selector 417, First Decoder 418, First Demodulator 419, First Receive Driver 420, Photodiode (PD) 421 .

The controller 412 processes data for data transmission and reception according to visible light communication, controls the first encoder 413, the first decoder 48, and the selector 417, and performs the overall operation of the visible light communication terminal 400. To control.

The controller 412 generates and transmits a response for allowing or rejecting a request for changing or releasing the allocated resource from the resource allocating apparatus in the allocated time slot. Here, the change request of the allocated resource may be a change request of a band or time slot being used by the visible light communication terminal 400 or a change request for both band and 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 allocating apparatus may request to change the band 1 to the selected band by selecting one band from the bands 2 to 6. have. The controller 412 then transmits a response allowing or rejecting the band change to the selected band.

Alternatively, when the resource allocation apparatus requests release of band 1 being used by the visible light communication terminal 400, the controller 412 may transmit a response indicating whether the service is interrupted through the band 1. Selection of whether to stop the service may 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 the modulated data to the first transmission driver 415.

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

The LED 416 is a light emitting device provided to transmit transmission data to an external device using an optical signal, and is driven by the first transmission driver 415. There are various types of light emitting devices that a visible light communication terminal can have, and each light emitting device has a different band according to its characteristics. Therefore, the kind of band which can be used is decided according to the wavelength characteristic of the light emitting element provided in a visible light communication terminal.

The photodiode 421 is a photosensitive device that senses an optical signal transmitted from an external device. The photodiode 421 receives an optical signal including received data from a light source 210 and converts it into an electrical signal to the first reception driver 420. Output

The first reception driver 420 is a driver for the photodiode 421 and adjusts the band detection of the photodiode 421 according to the band selected by the selection unit 117. The first reception driver 420 outputs an electrical signal input from the photodiode 421 to the first demodulator 419.

The first demodulator 419 demodulates the electrical signal input from the first reception driver 420 into data according to the optical wireless communication method, thereby outputting the received data to the first decoder 418.

The first decoder 418 decodes the received received data and outputs the received data to the controller 412, and the controller 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 kinds of updatable storage data, and the like. The first memory 411 stores information about allocated time slots and bands according to an embodiment of the present invention. Save it.

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. 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 device 215 and a light source 210 connected thereto. Specifically, the communication control device 215 may include a second memory 551, a controller 552, a second encoder 553, and a second light source 210. And a second modulator 554, a second decoder 555, a second demodulator 556, and a first input / output terminal 559.

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

In particular, 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, and the selection controller Since the operation of the operation similar to each component of the visible light communication terminal, and plays a similar role, 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, and according to an embodiment of the present invention, resource allocation state information for each terminal, that is, Stores information about allocated time slots and bands.

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

The controller 552 controls the overall operation of the resource allocation apparatus, and all operations necessary for performing time slot and band allocation and management for each terminal belonging to the service area of the light source 210 according to an embodiment of the present invention. To control. In detail, the controller 552 searches for an assignable resource when there is a terminal attempting initial access to the service area of the light source 210. If there is no allocable resource, that is, a time slot and a band, the controller 552 determines a terminal for recovering allocated resources from existing terminals based on the resource allocation state stored in the second memory 551.

The method for allocating to an initially attempted terminal by changing resources allocated to existing terminals is as follows. In detail, the controller 552 selects a terminal capable of using a multi-band from among the existing terminals, changes the band being used in the selected terminal to another band, or requests the release of the band being used. This method changes only the band without changing the time slot.

In addition, if multiple terminals have different bands, communication with multiple terminals is possible in the same time slot. In this case, the controller 552 selects a terminal capable of multi-band use among existing terminals, and assigns a time slot assigned to the selected terminal to a terminal using a band that does not overlap with a band being used by the selected terminal. Request a change. This method only changes the time slot.

In addition, the controller 552 requests to change the time slot allocated to the selected terminal to the time slot allocated to the other terminal while also changing the band used by the selected terminal to a band that does not overlap with the band used by the other terminal. do. This method is to change both time slots and bands.

As described above, the controller 552 determines whether to recover only the allocated band, only the time slot, or both the band and the time slot, based on the stored resource allocation state. According to the determination result, the controller 552 requests a change of the allocated resource to the determined terminal or requests for release. Then, the control unit 552 allocates the resources recovered from the terminal allowing for this request to the terminal attempting initial access.

Referring to FIG. 6, the operation of the visible light communication terminal 400 and the resource allocation apparatus 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 described as an example, and an example in which band 1 is used as an initial access band will be described.

Referring to FIG. 6, the resource allocation apparatus 600 establishes an initial connection and communication link with each of the terminals 1 to n 201, 202, 203, 204, 205, and 206 belonging to the service area of the light source 210. Then, the resource allocation apparatus 600 allocates time slots to 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 established link. Subsequently, the resource allocation apparatus 600 exchanges multi-band information with each terminal 1 to n (201, 202, 203, 204, 205, 206) in a time slot allocated to each terminal 1 to n (201, 202, 203, 204, 205, 206) in step 609, and the band determined through such band information exchange. And data is transmitted and received using the allocated time slot. Since the resource allocation process according to the initial access in each of the terminals 1 to n (201, 202, 203, 204, 205, 206) has already been described in detail with reference to FIG. 3, the operation in FIG.

In this case, the frame structure as shown in FIG. 7 may be used to transmit multi-band information. The resource allocation apparatus 600 may provide band information to or receive information from each terminal using an initial access band in a time slot allocated to each terminal. The first multi-band information field (Src_multi_info) 710 and the second multi-band information field (Des_multi_info) 715 of the frame structure of FIG. 7 may be used to exchange the multi-band information. The first multi-band information field (Src_multi_info) 710 includes multi-band information available in the resource allocation apparatus 600, and the second multi-band information field (Des_multi_info) 715 includes multi-band information available in the terminal. Is loaded. In addition, the time slot information field S_info 700 of FIG. 7 is used to allocate the time slot.

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

Here, the resource allocation apparatus 600 may separately exchange band information on the band information used by the terminal n + 1 207 using the frame structure of FIG. 7 as in step 609. Alternatively, in step 611, the terminal n + 1 207 may transmit band information that may be used by the terminal n + 1 207 using the frame structure of FIG. 7.

Accordingly, the resource allocation apparatus 600 may search for allocation resources based on band information obtained through exchange of available band information or multi-band information in the terminal n + 1 207 included in the initial access. Since the information on the band transmitted during the initial access is provided to the resource allocation apparatus 600, it is provided on the second multiband information field Des_multi_info 715 of the frame structure of FIG. 7. For example, when the band usable by the terminal n + 1 207 is band 1, only information on band 1 is set as a bit in the second multi-band information field Des_multi_info 715 and transmitted. In the first multiband information field (Src_multi_info) 710 and the second multiband information field (Des_multi_info) 715, bits are mapped according to a band combination, so that if a bit mapped to the available band is used, the multiband is used. Information exchange is possible.

The process of searching for a time slot and a band allocable to the terminal n + 1 207 in step 613 is as follows. In more detail, the resource allocation apparatus 600 searches for whether a band available in the terminal n + 1 207, for example, band 1, is used in another time slot. If there is no time slot that can be allocated, the band 1 is searched for being occupied by other terminals in each time slot. If the allocable time slot and band are not 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 communicating 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 for the band 1 to the selected terminal. By redistributing the resources recovered in this way, it is possible to communicate with the terminal n + 1 207 which has newly attempted access.

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

If UE2 202 is using some of bands 2 to 6 including band 1, or is using all of bands 1 to 6, the request for change of allocated resources uses band 1 in use from bands 2 to 6 A request to change to a band that is not in use. In addition, the release request of the allocated resource means a service stop request using band 1. At this time, since the time slot allocated to the terminal 2 202 is TS2, this change request is transmitted in the time slot TS2 section. The method of changing the allocated resource corresponds to a method of changing only the band without changing the time slot.

If UE 2 202 is using some of the bands 1 to 6, but there is no band overlapping with UE n 206 using some of the bands 1 to 5, the time slot allocated to UE 2 202 is used. Only change can be requested. In this case, the resource allocation apparatus 600 requests the terminal 2 202 to change the TS2 to the time slot TSn allocated to the terminal n 206. As such, when the change of the allocated resource is requested, only the time slot may be changed.

If the terminal 2 202 is using some of the bands 2 to 6 including the band 1, the terminal 2 (202) requests the change to the time slot allocated to the terminal n (206) and simultaneously uses the band being used by the terminal 2 (202). A change may be requested to a band that does not overlap with the band being used at n 206. That is, the resource allocation apparatus 600 may request to change 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 response to the release to the resource allocation apparatus 600. In this way, the resource allocation apparatus 600 recovers the allocated resources from the terminal 2 (202). Accordingly, in step 625, the resource allocation apparatus 600 transmits allocated resource information to allocate the resource recovered in step 625 to the terminal n + 1 207. In step 627, the terminal n + 1 207 transmits an acknowledgment of the allocated resource. In step 629, the terminal n + 1 207 transmits and receives data between the resource allocation apparatus 600 and the terminal n + 1 207. .

For example, when time slot TS2 and band 1 are recovered from terminal 2 (202), time slot TS2 and band 1 are allocated to terminal n + 1 (207). Such time slot information and band information are transmitted to the terminal n + 1 207 through the control information 235. Accordingly, the terminal n + 1 207 exchanges data with the resource allocation apparatus 600 by using band 1 in the allocated time slot TS2 section.

As described above, the present invention allocates a serviceable resource among various bands available to terminals belonging to a light source service area in a resource allocation apparatus, and then, if there is a terminal newly attempted to access, the terminal is used for the access attempt. Compare available resources with allocable resources. If there is no resource that can be allocated, it is searched whether there are existing terminals among the terminals that can communicate using resources other than the resources to be allocated to the terminal which attempted the connection. Then, after attempting to change the allocated resource to the searched terminal, and receives a response to allow this, the process of allocating the recovered resources to the terminal attempted to access.

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 the resource allocation device allocates resources. However, the communication control device or the light source may be configured to allocate resources. 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 allocating resources in a resource allocation apparatus of a visible light communication system,
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;
Recovering allocated resources from any one visible light communication terminal among other visible light communication terminals belonging to the light source service area when there is no resource to be allocated as a result of the determination;
And transmitting the information on the recovered resource to the initially connected visible light communication terminal.
The method of claim 1, wherein the resource,
At least one of a time slot and a band.
The method of claim 1, wherein recovering the allocated resource comprises:
Requesting a change of an allocated resource to any one of the other visible light communication terminals;
Receiving a response to the request from the selected terminal.
The process of claim 3, wherein the request for changing the allocated resource comprises:
A process of requesting a change in the allocated resource to a visible light communication terminal using a band which does not overlap with an available band of the initially connected visible light communication terminal while supporting the most bands of the other visible light communication terminals. Way for you.
The method of claim 2, wherein recovering the allocated resource comprises:
And requesting a change in at least one of a time slot and a band allocated to the at least one visible light communication terminal.
The method of claim 1, wherein the determining of whether there is a resource to allocate 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 determining of whether there is a resource to allocate comprises:
Exchanging multi-band information with the initially connected visible light communication terminal;
Acquiring available band information of the initially accessed visible light communication terminal by exchanging the multiband information;
And determining whether there is a band to be allocated based on the obtained available band information.
The method of claim 1, wherein the information on the recovered resources is
And transmitting the information to the initially connected visible light communication terminal using control information.
The method of claim 1,
And transmitting and receiving data to and from the initially connected visible light communication terminal using the allocated band included in the recovered resource in the allocated time slot included in the recovered resource.
In the resource allocation device of the visible light communication system,
One light source,
Receives an initial connection from the visible light communication terminal through the light source, determines whether there is a resource to be allocated to the visible light communication terminal, and if there is no resource to allocate, any one of other visible light communication terminals belonging to the light source service area And a control unit for recovering the allocated resources from the visible light communication terminal, and transmitting information on the recovered resources to the initially connected visible light communication terminal.
The method of claim 10, wherein the resource,
And at least one of a time slot and a band.
The method of claim 10, wherein the control unit,
And requesting a change of the allocated resource to any one of the other visible light communication terminals, and receiving a response to the request from the selected terminal.
13. The apparatus according to claim 12,
A resource allocation apparatus for requesting a change of the allocated resource to a visible light communication terminal using a band which does not overlap with an available band of the initially connected visible light communication terminal while supporting the most bands of the other visible light communication terminals. .
13. The apparatus according to claim 12,
And requesting a change in at least one of a time slot and a band allocated to the one visible light communication terminal.
The method of claim 10, wherein the control unit,
And determining whether there is a band to allocate based on available band information of the initially connected visible light communication terminal.
The method of claim 10, wherein the control unit,
After exchanging multiband information with the initially connected visible light communication terminal, acquiring available band information of the initially connected visible light communication terminal through the exchange of the multiband information, and assigning the available band information based on the obtained available band information. And determining whether there is a band.
The method of claim 10, wherein the information on the recovered resources,
The resource allocation apparatus, characterized in that for transmitting to the initially connected visible light communication terminal using the control information.
The method of claim 10, wherein the control unit,
And transmitting and receiving data to and from the initially connected visible light communication terminal using an allocation band included in the recovered resource in the allocated time slot included in the recovered resource.

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