Patent Description:
An intelligent transportation system ( ITS) is intended to establish, by integrating and using advanced information technologies, communications technologies, sensing technologies, control technologies, computer technologies, and the like, a real-time, accurate, and highly-efficient comprehensive transportation management system that plays an all-round role in a wide range.

The ITS may effectively use traffic facilities, reduce traffic load and environmental pollution, ensure traffic safety, and improve transportation efficiency. The ITS indicates a future development direction of a transportation system, and is an important part of an intelligent city. Main participants in the ITS are road infrastructures, vehicles, management centers, users, and the like.

As main vehicles, the vehicles in the ITS need to communicate with other vehicles, road infrastructures, traffic management centers, users, and the like, which is also referred to as a vehicle to everything (V2X).

When the V2X is implemented based on a wireless communications network, such as LTE and <NUM>, a vehicle is used as a mobile device to travel between serving cells of base stations. Therefore, the base station needs to be switched to ensure continuity of a service provided for the vehicle.

Currently, it is determined that a base station is switched based on signal strength of a base station received by a mobile device, for example, a mobile phone. When signal strength of a base station that currently serves the mobile device received by the mobile device is less than signal strength of another base station, the another base station is used as a next base station that serves the mobile device. Then the mobile device establishes a communication connection to the next base station that serves the mobile device, and finally, the service provided by the base station for the mobile device is handed over from the base station that currently serves the mobile device to the next base station that serves the mobile device.

However, compared with a conventional mobile device, for example, a mobile phone, a vehicle is a new mobile device, and is characterized by a higher moving speed, a lower requirement on a transmission delay, and a higher requirement on service continuity. In this case, timeliness and reliability of base station handover cannot be determined based on signal strength of a base station only, and there may even be a case in which the vehicle has crossed a serving cell and the base station handover is not completed.

<CIT> discloses that advance handover notice is given to a "target" base station of a group of mobile radio connections that will soon be handed over the to the target base station from a current, "serving" base station. This advance notice permits the target base station to reserve resources and prepare for the handovers of the mobile radio connections. In addition, the handover operation is initiated earlier than it would be otherwise.

<CIT> discloses a V2X communication base station cluster system, cluster method and cluster server. The method comprises: a first base station receives and forwards the register information of a vehicle, and the vehicle accesses the base station; the register information, the position information and the motion state information of the vehicle is received; comparing the stored base station distribution condition according to the received position and motion state information, and it is predicated that each base station which the vehicle is possible to pass or arrive in the next presetting time slot or a presetting distance.

The present invention provides a base station handover method in claim <NUM> and device based on a motion status of a mobile device in claim <NUM>, which can start base station handover at a more proper time, and quickly and seamlessly complete the base station handover, so as to meet requirements of security assurance and efficiency improvement.

According to a first aspect, a base station handover method based on a motion status of a mobile device is provided, and the method includes:.

The threshold is set based on an assumption that the mobile device has established the second communication connection to the second base station, and a required time from the initiating the handover from the first base station to the second base station to the completing the handover from the first base station to the second base station.

In a possible implementation, the predicting, based on the current location and the motion status of the mobile device, duration from a current moment to a moment when a base station that serves the mobile device completes handover from a first base station to a second base station includes:.

In a possible implementation, the handover boundary is determined based on an intensity interface between signal strength of the first base station and signal strength of the second base station; or the handover boundary is determined based on a section of an intersection point between a surface of signal coverage space of the first base station and a surface of signal coverage space of the second base station.

In a possible implementation, that the mobile device establishes the second communication connection to the second base station includes:
the second communication connection is established when the mobile device enters signal coverage space of the second base station.

In a possible implementation, the signal coverage space of the base station is determined based on a location and the signal strength of the base station.

In a possible implementation, the initiating the handover from the first base station to the second base station includes:
indicating, to the first base station, the second base station, and/or the mobile device, that the base station that serves the mobile device is switched from the first base station to the second base station.

In a possible implementation, that the handover from the first base station to the second base station is completed includes:
serving the mobile device by the first base station through the first communication connection is switched to serving the mobile device by the second base station through the second communication connection.

In a possible implementation, that the first base station is switched to the second base station includes:
the first base station hands over a service provided for the mobile device to the second base station.

In a possible implementation, the next base station that serves the mobile device is determined based on the current location and a current direction of the mobile device; or the next base station that serves the mobile device is determined based on the base station that currently serves the mobile device and a current direction of the mobile device.

In a possible implementation, the base station that currently serves the mobile device is determined based on the current location of the mobile device.

In a possible implementation, the motion status further includes an angular velocity.

According to a second aspect, a base station handover device based on a motion status of a mobile device is provided, and the device includes:.

The device further includes:
a setting module, configured to set the threshold based on an assumption that the mobile device has established the second communication connection to the second base station, and a required time from the initiating the handover from the first base station to the second base station to the completing the handover from the first base station to the second base station.

In a possible implementation, that the prediction module predicts, based on the current location and the motion status of the mobile device, duration from a current moment to a moment when a base station that serves the mobile device completes handover from a first base station to a second base station includes:.

In a possible implementation, the initiating the handover from the first base station to the second base station includes:
the handover module indicates, to the first base station, the second base station, and/or the mobile device, that the base station that serves the mobile device is switched from the first base station to the second base station.

The following clearly and completely describes the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some rather than all of the embodiments of the present invention. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

It should be understood that the embodiments of the present invention may be applied to any mobile device in a wireless communications network. A vehicle is only one of typical mobile devices that are characterized by a higher moving speed, a lower requirement on a transmission delay, and a higher requirement on service continuity. For ease of description, the embodiments of the present invention are described by using a vehicle as an example. However, this shall not constitute a limitation on an applicable mobile device.

In an ITS, precise positioning is a precondition for performing location-based traffic control and resource scheduling. Therefore, the vehicle needs to determine a location of the vehicle, and update the location based on a traveling direction, a speed, an acceleration, and an angular velocity of the vehicle. This may be implemented based on technologies such as a global positioning system and an electronic map.

In the wireless communications network, a location and signal strength of a base station affect signal coverage space of the base station. Therefore, a dynamic location of a traveling vehicle relative to each base station may be used to determine a base station that currently serves the vehicle and predict a base station that may serve the vehicle in the future.

In a specific area, a distribution diagram of signal coverage space of base stations is constructed based on locations and signal strength of the base stations. A location determines a center of signal coverage space of a base station, and signal strength determines a size of the signal coverage space of the base station. In addition, environmental factors such as astronomical factors and geographical factors may also affect the size and a shape of the signal coverage space of the base station.

If signal coverage space of one base station and signal coverage space of another base station partially overlap, a location for performing handover between the two base stations in an overlapping area may be determined by using the following two methods.

<FIG> is a schematic diagram of a method <NUM> for determining a handover boundary of base stations in an overlapping area.

As shown in <FIG>, signal coverage space of a base station A and signal coverage space of a base station B partially overlap.

In an overlapping area, signal strength of the base station A is compared with signal strength of the base station B at all locations to form an intensity interface. On the interface, the signal strength of the base station A is equal to the signal strength of the base station B; on one side of the interface, the signal strength of the base station A is greater than the signal strength of the base station B; and on the other side of the interface, the signal strength of the base station A is less than the signal strength of the base station B.

The interface is used as a boundary at which a base station that serves a vehicle is switched between the base station A and the base station B when the vehicle is traveling. When the vehicle enters the side on which the signal strength of the base station A is greater than the signal strength of the base station B, the base station is switched from the base station B to the base station A. When the vehicle enters the side on which the signal strength of the base station A is less than the signal strength of the base station B, the base station is switched from the base station A to the base station B.

In an overlapping area, a section is taken at an intersection point between a surface of signal coverage space of the base station A and a surface of signal coverage space of the base station B. The base station A is preferably used on a side that is of the section and that faces the base station A, and the base station B is preferably used on a side that is of the section and that faces the base station B.

The section is used as a boundary at which a base station that serves a vehicle is switched between the base station A and the base station B when the vehicle is traveling. When the vehicle enters the side that is of the section and that faces the base station A, the base station is switched from the base station B to the base station A. When the vehicle enters the side that is of the section and that faces the base station B, the base station is switched from the base station A to the base station B.

<FIG> is a schematic diagram of a base station handover method based on a motion status of a mobile device.

As shown in <FIG>, a base station that serves a vehicle is switched when the vehicle is traveling.

A base station that currently serves the vehicle may be determined based on distribution of signal coverage space of base stations and a current location of the vehicle, and it is assumed that the base station is a base station A. The vehicle has established a communication connection a to the base station A, and the base station A is serving the vehicle through the communication connection a.

A next base station that serves the vehicle may be determined based on the distribution of the signal coverage space of the base stations and the current location and a current direction of the vehicle, or the base station A that currently serves the vehicle and the current direction of the vehicle, and it is assumed that the next base station is a base station B. The vehicle needs to establish a communication connection b to the base station B, and the base station B is to serve the vehicle through the communication connection b.

When the vehicle is in signal coverage space of the base station A, the base station A still serves the vehicle. To be specific, while the vehicle maintains the communication connection a to the base station A, the vehicle pre-establishes the communication connection b to the base station B when the vehicle travels into signal coverage space of the base station B.

Duration from a current moment to a moment when the base station that serves the vehicle completes handover from the base station A to the base station B may be determined based on a handover boundary between the base station A and the base station B in an overlapping area, the current location and a motion status of the vehicle, and a time required for the vehicle to travel from the current location to the handover boundary based on the motion status. The motion status of the vehicle includes at least a traveling direction, a speed, and an acceleration, and may further include an angular velocity, and the like of the vehicle.

The duration dynamically changes with traveling of the vehicle. When the duration is reduced to a certain preset threshold, base station handover is initiated. To be specific, that the base station that serves the vehicle is switched from the base station A to the base station B is indicated to the base station A, the base station B, and/or the vehicle. Because a communication connection between the vehicle and the base station B has been pre-established, the threshold may be set based on a required time from initiating to completion of the base station handover. In this period, a service provided for the vehicle is mainly handed over from the base station A to the base station B. The time may be obtained through calculation, measurement, or statistics collection.

Because motion statuses are different for all vehicles, an initiation moment of the base station handover determined by using the foregoing method may correspond to different locations for the vehicles.

After the base station handover is completed, to be specific, after serving the vehicle by the base station A through the communication connection a is switched to serving the vehicle by the base station B through the communication connection b, the communication connection a between the vehicle and the base station A may be broken, or may be broken only when the vehicle travels out of the signal coverage space of the base station A.

<FIG> is a schematic flowchart of a base station handover method based on a motion status of a mobile device. In a specific embodiment, the method may be performed by a base station, or may be performed by a mobile device. In an intelligent driving field, the method may be performed by a mobile service switching center. As shown in <FIG>, the method S <NUM> includes the following steps:.

<FIG> is a schematic diagram of modules of a base station handover device based on a motion status of a mobile device.

As shown in <FIG>, the apparatus <NUM> includes an obtaining module <NUM>, a prediction module <NUM>, and a handover module <NUM>.

The obtaining module <NUM> is configured to obtain a current location and a motion status of a mobile device. In all possible embodiments, the motion status includes a direction, a speed, and an acceleration, and may further include an angular velocity.

The prediction module <NUM> is configured to predict, based on the current location and the motion status of the mobile device, duration from a current moment to a moment when a base station that serves the mobile device completes handover from a first base station to a second base station, where the first base station is a base station that currently serves the mobile device, and the second base station is a next base station that serves the mobile device.

The prediction module may determine, based on the current location and a current direction of the mobile device, the next base station that serves the mobile device. Alternatively, in another manner, the prediction module <NUM> may determine, based on the base station that currently serves the mobile device and a current direction of the mobile device, the next base station that serves the mobile device.

The handover module <NUM> is configured to: after the mobile device maintains a first communication connection to the first base station and establishes a second communication connection to the second base station, initiate the handover from the first base station to the second base station when the duration is reduced to a set threshold.

In an implementation, the handover module in the apparatus <NUM> is further configured to set the threshold based on an assumption that the mobile device has established the second communication connection to the second base station, and a required time from the initiating the handover from the first base station to the second base station to the completing the handover from the first base station to the second base station.

During specific implementation, the prediction module determines a handover boundary between the first base station and the second base station, and determines the duration based on the time required for the mobile device to reach the handover boundary from the location based on the motion status. In a manner, the prediction module determines the handover boundary based on an intensity interface between signal strength of the first base station and signal strength of the second base station. Alternatively, in another manner, the prediction module determines the handover boundary based on a section of an intersection point between a surface of signal coverage space of the first base station and a surface of signal coverage space of the second base station.

In a more specific possible handover manner, after the mobile device maintains the first communication connection to the first base station and establishes the second communication connection to the second base station, and when the duration is reduced to a set threshold, the handover module indicates, to the first base station, the second base station, or the mobile device, that the base station that serves the mobile device is switched from the first base station to the second base station.

The foregoing solutions may be implemented by a vehicle, a base station, a mobile service handover center, or another functional entity. The foregoing apparatus <NUM> may be a processor with some modules having calculation and processing capabilities. The implementers need to understand distribution of signal coverage space of base stations, including a handover boundary between the base stations having overlapping coverage space, and a current location and a motion status of a vehicle.

It should be understood that the apparatus <NUM> according to this embodiment of the present invention may correspond to an execution body of the method <NUM> in the embodiments of the present invention, and the foregoing and other operations and/or functions of the modules in the apparatus <NUM> are respectively intended to implement corresponding procedures of the method <NUM>. For brevity, details are not described herein again.

It should be understood that in the embodiments of the present invention, "B corresponding to A" indicates that B is associated with A, and B may be determined based on A. However, it should be further understood that determining B based on A does not mean that B is determined based on A only, in other words, B may also be determined based on A and/or other information.

It should be further understood that, unless the context clearly supports an exception, a single form "one" ("a", "an", and "the") used in this specification also intends to include a plural form. It should be further understood that, "and/or" used in this specification includes any or all possible combinations of one or more associated listed items.

A person of ordinary skill in the art may be aware that, in combination with the embodiments disclosed in this specification, units and algorithm steps in the examples may be implemented by electronic hardware, computer software, or a combination thereof. To clearly describe the interchangeability between hardware and software, the foregoing has generally described compositions and steps of each example based on functions. Whether the functions are performed by the hardware or the software depends on particular applications and design constraints of the technical solutions.

It may be clearly understood by a person skilled in the art that, for convenient and brief description, for specific operating processes of the foregoing system, apparatus, and unit, refer to corresponding processes in the foregoing method embodiments.

In some embodiments provided in this application, it should be understood that the disclosed system, apparatus, and method may be implemented in other manners. For example, a plurality of units or components may be combined or integrated in another system, or some features may be ignored or not performed. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections may be implemented through some interfaces, indirect couplings or communication connections between the apparatuses or units, or electrical connections, mechanical connections, or connections in other forms.

Some or all of the units may be selected based on actual requirements to achieve the objectives of the solutions of the embodiments of the present invention.

When being implemented in the form of the software functional unit and sold or used as an independent product, the integrated unit may be stored in a computer-readable storage medium. Based on such an understanding, the technical solutions of the present invention essentially, or the part contributing to the prior art, or all or some of the technical solutions may be implemented in a form of a software product. The computer software product is stored in a storage medium and includes several instructions for instructing a computer device (which may be a personal computer, a server, or a network device) to perform all or some of the steps of the methods described in the embodiments of the present invention. The foregoing storage medium includes: any medium that can store program code, such as a USB flash drive, a removable hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk, or an optical disc.

Claim 1:
A base station handover method based on a motion status of a mobile device, performed by a base station, a mobile device or a mobile service switching center, comprising:
obtaining (S110) a current location and a motion status of a mobile device;
predicting (S120), based on the current location and the motion status of the mobile device, duration from a current moment to a moment when a base station that serves the mobile device completes handover from a first base station to a second base station, wherein the first base station is a base station that currently serves the mobile device, and the second base station is a next base station that serves the mobile device, and the motion status comprises at least a combination of a direction, a speed and an acceleration of the mobile device; and
after the mobile device maintains a first communication connection to the first base station and establishes a second communication connection to the second base station, initiating (S140) the handover from the first base station to the second base station when the duration is reduced to a set threshold;
wherein the method further comprising:
setting the threshold based on an assumption that the mobile device has established the second communication connection to the second base station, and a required time from the initiating the handover from the first base station to the second base station to the completing the handover from the first base station to the second base station.