WO2020101155A1

WO2020101155A1 - Method for supporting vehicle mobility in vlc network

Info

Publication number: WO2020101155A1
Application number: PCT/KR2019/010803
Authority: WO
Inventors: 김상옥; 김병오; 윤상호; 노승완
Original assignee: ㈜유양디앤유
Priority date: 2018-11-13
Filing date: 2019-08-23
Publication date: 2020-05-22

Abstract

A method for supporting vehicle mobility in a VLC network is disclosed. According to some of the proposed techniques, prior to an occurrence of a handover process, a handover pre-notification is provided to a target cell for a vehicle to move shortly thereafter from a current serving cell to the target cell. The pre-notification allows the target cell to prepare for an upcoming handover, including reserving resources for the handover, prior to the occurrence of the handover process. According to some other proposed techniques, as a vehicle travels, while street lights located in front of a serving cell in the driving direction of the vehicle are added to a current serving cell, some serving street lights located at the rear end of the serving cell are removed from the current serving cell. That is, as the vehicle travels, the serving cell is reconfigured.

Description

Method for supporting vehicle mobility in VLC network

The present invention mainly relates to Visible Light Communication (VLC) between a vehicle and several LED street lights.

The content described in this section merely provides background information for the present invention and does not constitute a prior art.

Visible Light Communication (VLC) is a communication method that directly transmits an optical signal to the atmosphere using light in the visible spectrum as a medium. VLC communication is characterized by wide spectrum, high transmission rate and small interference, and can be used for transmission of traffic-intensive service flows. Outdoor VLC (Outdoor VLC) is mainly discussed in the Intelligent Transportation System (ITS). ITS has many LED devices, such as LED street lights, traffic lights, and automotive LED lights, which has the advantage of being able to build a VLC system at a low cost.

The present invention mainly relates to visible light communication between a vehicle driving on a road and various street lights. In such a scenario, the lighting coverage of a street light can be viewed as wireless coverage, typically referred to as a cell in a cellular communication system. When a vehicle crosses between adjacent cells, there may be multiple handovers. Since the lighting coverage of the street light is very small compared to that of the cellular network, the time that the driving vehicle stays in one cell will be very short. Frequent switching of a VLC link to a vehicle between multiple cells can cause severe signaling overhead, delay, data disruption and / or degradation of quality of service (QoS).

The handover procedure is typically based on each mobile device monitoring the received signal strength of signals transmitted by the serving base station and neighboring base stations. Handover is generally initiated when two main conditions are met: first, the received signal strength of the current serving base station is less than the received signal strength of the neighboring base station, and second, the difference in received signal strength between the two base stations is a specific time period. While it is greater than a certain threshold.

This handover procedure works fairly well in many cellular communication situations, but it does not work well in VLC communication situations, for example, between a vehicle moving at high speed and a street light with small lighting coverage. That is, the original connection with the serving VLC base station may be lost / dropped before a handover request is generated and the handover connection with the new VLC base station is properly established. Moreover, in typical indoor scenarios, street lights installed on roads are usually not, while the lighting coverages are generally partially overlapping each other to illuminate the entire interior space.

The present disclosure is intended to provide various techniques for supporting mobility of a vehicle in a VLC network including street lights on a road that perform VLC communication with a vehicle.

According to some proposed techniques, prior to the handover process taking place, the target cell is provided with a prior handover notification for the vehicle to move from the current serving cell to the target cell soon. Prior notification allows the target cell to prepare for an upcoming handover, including reserving resources for handover, before the handover process occurs. Advance handover notification is possible because the path of the moving vehicle can be known or predicted and the target cell can be known or predicted accordingly. Through the reservation of resources, the handover process can be completed faster than otherwise. In this way, for vehicles moving at high speed, the probability of successful handover is increased.

According to some other proposed techniques, the coordination node of the VLC network controls a group of streetlights serving the vehicle to follow the vehicle based on the vehicle's current location and the vehicle's speed. That is, as the vehicle travels, street lights located in front of the serving cell in the driving direction of the vehicle are added to the current serving cell, and some serving street lights located at the rear end in the serving cell are removed from the current serving cell. According to this technique, as the vehicle travels on the road, the serving cell for the vehicle is reconstructed, thereby eliminating the need for an existing handover procedure.

According to an aspect of the present disclosure, a method for supporting mobility of a vehicle includes: before a handover initiation of a VLC connection occurs, a base station of a serving cell transmits a pre-handover notification to a base station of a target cell that is a cell adjacent to the serving cell. ; And in response to the advance handover notification, the base station of the target cell reserves a resource for supporting handover of the VLC connection. Here, a plurality of street lights controlled by a base station of the serving cell form the serving cell, and a plurality of street lights controlled by a base station of the target cell form the target cell. The method includes: determining, by the base station of the serving cell, to handover the vehicle to the base station of the target cell; And performing the handover between the base station of the serving cell and the base station of the target cell.

Embodiments of the method may further include one or more of the following features.

In some embodiments, the advance handover notification includes information identifying the communication module of the vehicle.

In some embodiments, the method further includes, in response to the advance handover notification, transmitting a response message including information necessary for the base station of the target cell to access the target cell to the base station of the serving cell. .

In some embodiments, the step of deciding to handover the vehicle to the base station of the target cell is performed in a situation where the vehicle is located in the lighting coverage of the last street lamp among a series of street lights forming the serving cell.

In some embodiments, the step of deciding to handover the vehicle to the base station of the target cell is based on the time when the last street light in the serving cell receives an ACK message informing the reception of a data packet from the vehicle. And determining to handover to the base station of the target cell.

In some embodiments, determining to handover the vehicle to the base station of the target cell comprises: receiving, by the base station of the serving cell, a handover request message from the vehicle; And determining to handover the vehicle to the base station of the target cell based on the time point when the handover request message is received.

In some embodiments, the step of performing the handover may include: a base station of the serving cell transmitting a handover request message to the base station of the target cell; And transmitting a handover indication message including information necessary for the base station of the serving cell to access the target cell with the vehicle.

In some embodiments, when two or more vehicles are located in the coverage area of the serving cell, the base station of the serving cell provides a VLC service to each vehicle using a multiple access technique.

According to another aspect of the present disclosure, a method of supporting mobility of a vehicle includes determining a current position and speed of the vehicle within a group of street lights serving the vehicle; Determining a predicted future location of the vehicle based on the location and speed of the vehicle; Changing a part of the street lights constituting the street light group so that the street light group may have a serving area covering the predicted future location of the vehicle; And providing information regarding the changed streetlight group to base stations related to the changed streetlight group. Here, a plurality of street lights belonging to the street light group transmits VLC signals having the same data packet to each other.

In some embodiments, the step of changing a part of the street lights constituting the street light group includes adding at least one street light located in front of the street light group to the street light group, and at least one located at a rear side in the street light group. And removing the street light from the street light group.

In some embodiments, the step of changing a part of the street lights constituting the street light group includes adaptively changing the number of street lights belonging to the street light group in response to a traffic traffic condition of the road.

In some embodiments, the step of changing a part of the street lights constituting the street light group includes changing the number of street lights belonging to the street light group by time zone or day of the week.

In some embodiments, the step of changing a part of the street lights constituting the group of street lights further includes changing the number of street lights belonging to the group of street lights in response to the speed of the vehicle.

In some embodiments, the number of street lights included in the street light group is changed in units of the number of street lights controlled by one base station.

In some embodiments, the current position and speed of the vehicle is determined based at least in part on the time points when each street light belonging to the street light group receives an ACK message indicating the reception of a data packet from the vehicle.

In some embodiments, the method further includes receiving a report regarding the current location or speed of the vehicle from the vehicle.

In some embodiments, when two or more vehicles are located in the coverage area of the streetlight group, the streetlight group provides a VLC service to each vehicle using multiple access techniques.

1 is a diagram illustrating an exemplary V2I scenario in which visible light communication is performed between a vehicle and various LED street lights.

2 is a conceptual diagram illustrating a pre-handover preparation technique of a VLC link according to another embodiment of the present invention.

3 is a flowchart illustrating a method for early handover according to an embodiment of the present invention.

4 is a view for explaining a technique for a serving street light group to follow a vehicle according to another embodiment of the present invention.

5 is a view for explaining a technique for adaptively changing the number of street lights belonging to one street light group according to traffic traffic conditions according to another embodiment of the present invention.

6 is a flowchart illustrating a method of supporting mobility of a vehicle according to an embodiment of the present invention.

This research invention patent was an invention patent that was filed by Yuyang D & U, a supervisory agency under the support of the Information and Communication Broadcasting Standard Development Support Project of the Ministry of Science and ICT (Task No .: 2018-0-00933).

Hereinafter, some embodiments of the present invention will be described in detail through exemplary drawings. It should be noted that in adding reference numerals to the components of each drawing, the same components have the same reference numerals as possible even though they are displayed on different drawings. In addition, in describing the present invention, when it is determined that detailed descriptions of related well-known structures or functions may obscure the subject matter of the present invention, detailed descriptions thereof will be omitted.

In addition, in describing the components of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are only for distinguishing the component from other components, and the nature, order, or order of the component is not limited by the term. Throughout the specification, when a part is 'included' or 'equipped' a component, this means that other components may be further included rather than excluded, unless specifically stated otherwise. . In addition, terms such as '... unit,' and 'module' described in the specification mean a unit that processes at least one function or operation, which may be implemented by hardware or software or a combination of hardware and software.

1 is a diagram illustrating an exemplary V2I scenario in which visible light communication (VLC) is performed between a vehicle and various LED street lights.

The vehicle 10 is provided with a communication module (not shown) suitable for data communication by VLC technology, for example, on the side of the road 1, an illumination module that outputs visible light for illuminating the road 1, respectively Street lights equipped with (not shown) are arranged.

The communication module of the vehicle 10 includes an optical receiver and an optical transmitter, and data communication is possible in both directions. The communication module of the vehicle 10 may receive data and transmit it to, for example, a vehicle terminal (On Board Unit: OBU) (not shown). The communication module can be located, for example, on the front window or roof of the vehicle 10.

The lighting module of the street light 11 is configured to be suitable for data communication by VLC technology, so that data communication can be at least between the lighting module of the street light 11 and the communication module of the vehicle 10. The lighting module of each street light 11 is controlled by an associated base station 13, and it is also possible to communicate with each other between adjacent base stations 13. The base stations 13 can be connected to the backhaul network 20 through the associated coordination node 15. The coordination node 15 may be a router or switch. Alternatively, the vehicle and street light may use RF communication or IR communication to form an uplink path.

For convenience of description, in the following description, the terms "lighting module for street lamp" and the term "street lamp" may be used interchangeably. Similarly, the terms "communication module of vehicle 10" and the term "vehicle" can be used interchangeably.

Since the lighting coverage 12 of the street light 11 is very small compared to a cell of the cellular network, the time for the traveling vehicle 10 to stay in the lighting coverage area 12 of one street light 11 is very short. Frequent switching of the VLC link to the vehicle 10 between the plurality of street lights 11 may cause severe signaling overhead, delay, data interruption and / or degradation of quality of service (QoS).

As described below, the present invention expands communication coverage between a vehicle and a street light through grouping of street lights. As shown in FIG. 1, in some embodiments of the present invention, a plurality of street lights 11 are communicatively connected to each base station 13, and each base station 13 is associated with street lights 11 VLC communication can be controlled. Each base station 13 can control the related street lights 11 to transmit a VLC signal including the same data. Accordingly, it can be seen that the lighting coverages provided by the respective street lights 11 related to the same base station 13 form the VLC communication coverage, serving area or cell of the corresponding base station 13. In other words, a plurality of street lights are grouped to form one cell. All street lights in one cell are controlled by the same base station and synchronized with each other. Each streetlight group is identified by a group ID, and each streetlight can be identified by a streetlight ID. The header of the data packet transmitted by the street light may include a group identifier to which it belongs and its street light identifier. The payloads of data packets transmitted by each street light may all be the same.

Because all street lights in a cell transmit the same data, when moving within the cell, the vehicle receives a data packet from any one of a series of street lights in the cell. When the current streetlight is out of sight of the vehicle, the vehicle will immediately receive a data packet from the next streetlight. The vehicle may transmit an ACK message to the street light whenever it receives a data packet. Accordingly, based on which street light in the cell has received the ACK message, the base station can know or estimate at which point in the cell the vehicle in motion has reached the current cell. In addition, the base station may estimate the speed of the vehicle running in the cell based on the time between the series of street lights in the cell receiving the ACK message and each street light.

If the coverage of each street lamp in a cell overlaps each other, when the vehicle is out of the current street lamp coverage, the vehicle immediately receives a VLC signal from the next street lamp. That is, when the vehicle moves inside the cell, communication is always maintained without interruption. Thus, while passing street lights within the cell, the signaling overhead for switching the VLC link is eliminated.

On the other hand, as in the street lamp arrangement model illustrated in FIG. 1, there may be a non-covered area that is not illuminated between two adjacent street lights 11. In the non-coverage area, the VLC communication link will be interrupted. When the interval of the non-coverage area is called ' L ' [m], and the moving speed of the vehicle 10 is ' v ' [m / s], it is required until the vehicle 10 enters the next coverage area. Time is t = L / v [s]. During this time, the communication link is interrupted. According to one aspect of the present invention, when the vehicle 10 leaves the serving cell, the interruption is avoided by storing a larger amount of data to be lost in the buffer space until entering the next cell.

By estimating the total amount of data to be lost during this time and leaving enough buffer space for that data, the communication link can be kept healthy. If the average transfer rate is ' B ', the buffer space is G> B * t . The buffer size is related to the speed of the vehicle 10. That is, when the speed of the vehicle 10 is low, a larger buffer size will be required. When the speed of the vehicle 10 increases, the buffer size will decrease.

Meanwhile, while the vehicle 10 moves from the current cell to the next cell, handover is required to maintain the communication connection of the vehicle 10. In a cellular network, the handover process comprises three steps: a) handover initiation (also referred to as 'handover decision'), b) target cell selection and c) handover execution. It can be divided into (stage). Handover initiation is the task of deciding to switch the communication link from the current cell to another cell. This determination is usually made based on the strength of the received signal of the mobile device. When the received signal is weak, the mobile device decides to switch to another cell according to the switching time. Since several cell candidates are available, one of them must be selected as the target cell. Once the target cell is determined, a handover execution step occurs. In the handover execution phase, a message is exchanged between the mobile device and the support stations as well as the mobile exchange to transfer the communication session from the current cell to the target cell.

In a cellular network, since mobile devices are surrounded by numerous cells, selecting the optimal cell for handover is influenced by various factors. However, in the V2I scenario to which the VLC network is applied, the target cell is determined very simply and intuitively. That is, since the street lights 11 are arranged in a line on the road 1, the next cell arranged adjacent to the current cell is determined as the target cell. Therefore, in a V2I scenario to which a VLC network is applied, target cell selection may be omitted in the handover process or may be performed prior to the handover process.

Another difference between cellular networks and VLC networks is the cell size. Typically, cellular networks have cell sizes in the range of 1 to 20 km, and mobile devices take considerable time to move out of the serving cell. In a V2I scenario with a VLC network, each cell contains only a few streetlights placed at tens of meters apart, so the cell size is usually only a few hundred meters. Due to the high travel speed, the time it takes for the vehicle to move out of the serving cell is very short, so the probability of a handover drop is much higher than for a cellular network.

According to an embodiment of the present invention, prior to the handover process occurring, this problem is overcome by providing the target cell with a prior handover notification for the vehicle 10 to be moved from the current serving cell to the target cell soon. Prior notification allows the target cell to prepare for an upcoming handover, including reserving resources for handover of the VLC connection, before the handover process of the communication link to the vehicle 10 occurs. Advance handover notification is possible because the path of the moving vehicle 10 can be known or predicted and accordingly the target cell can be known or predicted in advance. Through the reservation of resources, the handover process can be completed faster than otherwise. In this way, for the vehicle 10 moving at high speed, the probability of a successful handover is seamlessly increased.

The advance handover notification may be made at any point from the time when the vehicle 10 forms a communication link with the current serving cell until the handover process is executed. However, it may be desirable that the prior handover notification is provided earlier as the vehicle speed increases. The advance handover notification may include information identifying the communication module of the vehicle 10 to be handed over. The advance handover notification may further include information regarding the estimated current speed of the vehicle 10 or timing to reach the target cell. The advance handover notification may be provided to the base station 13b of the target cell by the base station 13a of the serving cell or the coordination node 15. The base station 13b of the target cell may transmit a response message including information necessary to access the target cell to the base station 13a of the serving cell in response to the advance handover notification.

(S310) Before handover starts, the base station 13a of the serving cell pre-hands to the base station 13b of the target cell, which is a cell adjacent to the serving cell, based on the determination that the vehicle 10 is approaching the target cell. Send an over notification message.

(S320) In response to the advance handover notification message, the base station 13b of the target cell reserves sufficient resources to support handover of the vehicle's VLC communication link. The base station 13b of the target cell can transmit a response message including information necessary to access the target cell to the base station 13a of the serving cell so that the vehicle can quickly access the target cell.

(S330 to S340) Thereafter, a handover process including a handover start step and a handover execution step is performed. The handover process can typically be performed in a situation where the vehicle 10 is located within the lighting coverage of the last street light (e.g., street light marked 11 _last in FIG. 2) among the series of street lights that make up the serving cell.

The handover decision can be performed by the base station 13a of the serving cell. For example, the base station of the serving cell may decide to switch the VLC connection to the target cell based on the time when the last street light 11 _{last in the} cell receives the ACK message from the vehicle 10. Alternatively, the base station 13a of the serving cell may decide to switch the VLC connection to the target cell in response to receiving the handover request message from the vehicle 10. The vehicle 10 may transmit a handover request message to the base station 13a of the serving cell when a data packet including the identifier of the last street light is received. Furthermore, the base station 13a or the vehicle 10 of the serving cell may determine the timing to handover in a manner similar to that of the existing cellular network, based on the received signal strength (RSS) of the VLC signal.

In the handover execution step, the base station 13a of the serving cell transmits a handover request message to the base station 13b of the target cell, and transmits a handover indication message including information necessary to access the target cell 10 By sending it to, the vehicle 10 is instructed to hand over to the target cell. The vehicle 10 disconnects from the serving cell and connects to the target cell.

According to some embodiments of the present invention, the coordination node of the VLC network controls a group of street lights serving the vehicle to follow the vehicle, based on the current location of the vehicle and the speed of the vehicle. That is, as the vehicle travels, the street lights constituting the cell serving the vehicle are changed. In other words, as the vehicle travels, street lights located in front of the serving cell in the driving direction of the vehicle are added to the current serving cell, and at the same time, some serving street lights located at the rear end in the serving cell are removed from the current serving cell. In this embodiment, no vehicle is involved in changing the street lights that make up the serving cell. That is, signaling for switching is not required between the vehicle and the VLC network. Partial replacement of the street lights constituting the serving cell may be performed periodically, and more frequently as the vehicle speed increases to ensure that the serving cell follows the position of the vehicle. According to this technique, as the vehicle travels on the road, the serving cell for the vehicle is reconstructed, thereby eliminating the need for an existing handover procedure.

As described above, based on which streetlight in the serving cell has received the ACK message, the coordination node can know or estimate at which point in the current cell the driving vehicle has reached. In addition, it is possible to estimate the speed of a vehicle driving in the cell based on the time intervals between the series of street lights in the serving cell receiving the ACK message and each street light. Alternatively, the vehicle may periodically report its geographic location (or identifier of the street light on which the VLC link is established) and speed to the steering node.

When the vehicle first connects to the VLC network, the coordination node may set some street lights in the front and rear as a serving street light group based on the current location of the vehicle.

If the speed of the vehicle is doubled, the switching timing between the groups of street lights will also be doubled, and accordingly, from a network perspective, the traffic per unit time due to signaling for switching will also double. If the number of street lights included in one group is doubled in response to the speed of the vehicle being doubled, the switching timing between the street lights groups will remain the same.

The VLC network according to an embodiment of the present invention adaptively changes the number of street lights included in one group according to traffic traffic conditions or the speed of a vehicle currently serving. For example, as the traffic volume of the corresponding road increases, the number of street lights included in one group gradually or gradually decreases. Conversely, as the traffic traffic of the corresponding road decreases, the number of street lights included in one group gradually or gradually increases. The VLC network may change the number of street lights included in one group by time zone or day of the week.

All street lights belonging to one street light group may be street lights controlled by the same base station, or street lights belonging to different base stations may form one street light group. Further, the number of street lights included in one group may be changed in units of the number of street lights controlled by one base station.

The method shown in FIG. 6 can be performed by a coordination node on the VLC network.

(S610) The steering node determines the current position and speed of the vehicle in a group of street lights serving the vehicle. A plurality of street lights belonging to the street light group transmits VLC signals having the same data packet to each other. The coordination node can know or estimate which point in the streetlight group has reached the driving vehicle based on which streetlight in the streetlight group receives an ACK message indicating that a data packet has been received from the vehicle. Alternatively, the steering node may periodically receive a message from the vehicle informing of the vehicle's geographic location (or identifier of the street light on which the VLC link is established) and speed.

(S620) The steering node determines the predicted future position of the vehicle based on the position and speed of the vehicle.

(S630) The coordination node changes a part of the street lights constituting the serving street light group so that the street light group has a serving area covering the predicted future position of the vehicle. That is, the coordination node reconstructs the serving cell. For example, the coordination node adds at least one streetlight located in front of the streetlight group to the streetlight group, while removing at least one streetlight located behind the streetlight group from the streetlight group. The coordination node may adaptively change the number of street lights belonging to the street light group in response to the traffic traffic situation of the road on which the vehicle is running. For example, as the traffic volume of the corresponding road increases, the number of street lights belonging to the street light group gradually or gradually decreases. Conversely, as traffic traffic on the road becomes lower, the number of street lights belonging to the street light group gradually or gradually increases. The coordination node may change the number of streetlights belonging to the streetlight group by time zone or day of the week. The adjustment node may change the number of street lights belonging to the street light group in response to the speed of the vehicle.

(S640) The coordination node provides information regarding the changed streetlight group to base stations related to the changed streetlight group. Subsequently, through resource reconfiguration and bearer path change, a plurality of street lights belonging to the changed street light group transmits VLC signals having the same data packet.

Meanwhile, in some cases, two or more vehicles may be located in a cell supported by one streetlight group, such as a case where the size of the streetlight group is large or traffic is congested. The streetlight group can also provide services to these vehicles at the same time. This is known as multiple access in cellular networks. In cellular systems, a number of multiple access technologies have been developed, such as time-division multiple access (TDMA), code-division multiple access (CDMA), orthogonal frequency division multiple access (OFDMA). One of the solutions to a suitable multiple access method in a VLC network is to adopt the multiple access technology used in RF cellular systems. Many studies have been conducted to use multiple access techniques in VLC networks. In TDMA, each UE is given a time slot for transmission. In CDMA, a signal for each UE is assigned a unique orthogonal code, and a desired signal can be obtained using the assigned code. The design of multiple orthogonal codes such as optical orthogonal codes, unipolar m-sequences and Walsh-Hadamard codes is possible in a VLC network. OFDMA may be used to distribute orthogonal subcarriers to multiple UEs. In addition, wavelength division multiple access (WDMA) may be considered when a communication module of a street light supports signals that are distinguished by different colors.

The above description is merely illustrative of the technical idea of the present embodiment, and those skilled in the art to which this embodiment belongs may be capable of various modifications and variations without departing from the essential characteristics of the present embodiment. Therefore, the present embodiments are not intended to limit the technical spirit of the present embodiment, but to explain, and the scope of the technical spirit of the present embodiment is not limited by these embodiments. The scope of protection of the present embodiment should be interpreted by the claims below, and all technical spirits within the equivalent range should be interpreted as being included in the scope of the present embodiment.

CROSS-REFERENCE TO RELATED APPLICATION

This patent application is filed in Korea on November 13, 2018, Patent Application No. 10-2018-0138978, and is filed in Korea on November 13, 2018, the entire contents of which are incorporated herein by reference. Priority is claimed on No. 10-2018-0138982.

Claims

In a VLC network including street lights on the road performing VLC communication with a vehicle, in the method for supporting the mobility of the vehicle,

Before the handover initiation of the VLC connection occurs, the base station of the serving cell transmits a pre-handover notification to the base station of the target cell, which is a cell adjacent to the serving cell, where a plurality of street lights controlled by the base station of the serving cell are served. Forming a cell, and a plurality of street lights controlled by a base station of the target cell form the target cell;

In response to the advance handover notification, the base station of the target cell reserves a resource for supporting handover of the VLC connection;

The base station of the serving cell determines to handover the vehicle to the base station of the target cell; And

Performing the handover between a base station of the serving cell and a base station of the target cell;

How to include.
According to claim 1,

The advance handover notification,

And information identifying the communication module of the vehicle.
According to claim 1,

And in response to the advance handover notification, transmitting a response message including information necessary for the base station of the target cell to access the target cell to the base station of the serving cell.
According to claim 1,

Determining to handover the vehicle to the base station of the target cell,

The method is characterized in that it is performed in a situation where the vehicle is located in the lighting coverage of the last street lamp among a series of street lights forming the serving cell.
According to claim 1,

Determining to handover the vehicle to the base station of the target cell,

And determining that the vehicle is handed over to the base station of the target cell, based on the time when the last street light in the serving cell receives an ACK message indicating the reception of a data packet from the vehicle. .
In claim 1,

Determining to handover the vehicle to the base station of the target cell,

A base station of the serving cell receiving a handover request message from the vehicle; And

And determining to handover the vehicle to the base station of the target cell based on the time point when the handover request message is received.
According to claim 1,

Step of performing the handover,

The base station of the serving cell transmitting a handover request message to the base station of the target cell; And

Transmitting a handover indication message including information necessary for the base station of the serving cell to access the target cell with the vehicle.

Characterized in that it comprises, a method.
According to claim 1,

When two or more vehicles are located in the coverage area of the serving cell, the base station of the serving cell is characterized in that it provides a VLC service to each vehicle using a multiple access technique.
In a VLC network including street lights on the road performing VLC communication with a vehicle, in the method for supporting the mobility of the vehicle,

Determining a current position and speed of the vehicle in a group of street lights serving a vehicle, wherein a plurality of street lights constituting the group of street lights transmit VLC signals having the same data packet;

Determining a predicted future location of the vehicle based on the location and speed of the vehicle;

Changing a part of the street lights constituting the street light group so that the street light group may have a serving area covering the predicted future location of the vehicle; And

Providing information about the changed streetlight group to base stations related to the changed streetlight group

Including, method.
The method of claim 9,

The step of changing a part of the street lights constituting the street light group,

And adding at least one streetlight located in front of the streetlight group to the streetlight group, and removing at least one streetlight located rearward in the streetlight group from the streetlight group.
The method of claim 9,

The step of changing a part of the street lights constituting the street light group,

And adaptively changing the number of street lights belonging to the street light group in response to the traffic traffic situation of the road.
The method of claim 9,

The step of changing a part of the street lights constituting the street light group,

And changing the number of streetlights belonging to the streetlight group by time zone or day of the week.
The method of claim 9,

The step of changing a part of the street lights constituting the street light group,

And in response to the speed of the vehicle, changing the number of street lights belonging to the street light group.
The method of claim 9,

The number of street lights included in the street light group,

The method, characterized in that it is changed in units of the number of street lights controlled by one base station.
The method of claim 9,

The current position and speed of the vehicle,

Each of the streetlights belonging to the streetlight group is determined based at least in part on the time points at which an ACK message indicating the reception of a data packet is received from the vehicle.
The method of claim 9,

And receiving a report regarding the current location or speed of the vehicle from the vehicle.
The method of claim 9,

When two or more vehicles are located in a coverage area of the streetlight group, the streetlight group provides a VLC service to each vehicle using a multiple access technique.