WO2017202306A1 - 一种轨道交通中无线局域网的信道管理方法及相关设备 - Google Patents

一种轨道交通中无线局域网的信道管理方法及相关设备 Download PDF

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Publication number
WO2017202306A1
WO2017202306A1 PCT/CN2017/085538 CN2017085538W WO2017202306A1 WO 2017202306 A1 WO2017202306 A1 WO 2017202306A1 CN 2017085538 W CN2017085538 W CN 2017085538W WO 2017202306 A1 WO2017202306 A1 WO 2017202306A1
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WIPO (PCT)
Prior art keywords
access point
channel
trackside
trackside access
vehicle
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Application number
PCT/CN2017/085538
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English (en)
French (fr)
Inventor
张�林
阮卫
欧历云
Original Assignee
华为技术有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Application filed by 华为技术有限公司 filed Critical 华为技术有限公司
Priority to EP17802152.3A priority Critical patent/EP3457757B1/en
Publication of WO2017202306A1 publication Critical patent/WO2017202306A1/zh
Priority to US16/201,039 priority patent/US10736013B2/en

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/24—Reselection being triggered by specific parameters
    • H04W36/32—Reselection being triggered by specific parameters by location or mobility data, e.g. speed data
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W84/00—Network topologies
    • H04W84/005—Moving wireless networks
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/24—Reselection being triggered by specific parameters
    • H04W36/32—Reselection being triggered by specific parameters by location or mobility data, e.g. speed data
    • H04W36/324—Reselection being triggered by specific parameters by location or mobility data, e.g. speed data by mobility data, e.g. speed data
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
    • H04W4/30—Services specially adapted for particular environments, situations or purposes
    • H04W4/40—Services specially adapted for particular environments, situations or purposes for vehicles, e.g. vehicle-to-pedestrians [V2P]
    • H04W4/42—Services specially adapted for particular environments, situations or purposes for vehicles, e.g. vehicle-to-pedestrians [V2P] for mass transport vehicles, e.g. buses, trains or aircraft
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/04—Wireless resource allocation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W84/00—Network topologies
    • H04W84/02—Hierarchically pre-organised networks, e.g. paging networks, cellular networks, WLAN [Wireless Local Area Network] or WLL [Wireless Local Loop]
    • H04W84/10—Small scale networks; Flat hierarchical networks
    • H04W84/12—WLAN [Wireless Local Area Networks]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
    • H04W88/08—Access point devices

Definitions

  • the present application relates to the field of communications, and in particular, to a channel management method and related device for a wireless local area network in rail transit.
  • a wireless local area network (WLAN) technology can be used to set up a vehicle-to-ground communication system.
  • a wireless communication link (such as a mesh (mesh) link or a wireless distribution system (WDS) link) is established between the in-vehicle access point and the trackside access point.
  • the wireless communication link can support wireless communication between the in-vehicle access point and the trackside access point.
  • the device of the passenger on the vehicle can access the network via the onboard access point and further via the trackside access point.
  • the car access point uses the same channel as all trackside access points.
  • the in-vehicle access point switches between multiple track-side access points (English: hand over).
  • the onboard access point monitors the signal of the trackside access point. If the vehicle access point finds that the signal strength of a trackside access point meets a preset threshold, the in-vehicle access point can establish a wireless communication link with the trackside access point.
  • the vehicle access point finds that the signal strength of the trackside access point with which the wireless communication link was established is getting weaker and weaker, while the signal of the other trackside access point is getting stronger.
  • the in-vehicle access point may disconnect the original wireless communication link and establish a new wireless communication link with another trackside access point.
  • Trackside access points may be interfered by radar or other signals, and interference may be avoided if the trackside access point switches (English: switch) to other channels.
  • the trackside access points after switching channels are different from other trackside access points and the channels used by the car access points, which affects the establishment of the wireless communication link. If the trackside access point does not switch its working channel, the interference will affect the establishment of the wireless communication link. Further, in some local regulations, when an access point uses certain channels as a working channel, it must switch its working channel if a radar signal is detected. Therefore, interference from radar or other signals will affect the switching of the vehicle access point between multiple track access points.
  • a channel management method, device and system for wireless local area networks in rail transit are provided to ensure the same channel between trackside access points.
  • the first aspect discloses a channel management method for a wireless local area network in rail transit, the method comprising:
  • the first trackside access point changes the working channel of the first trackside access point to
  • the second channel indicates that the in-vehicle access point changes the working channel of the in-vehicle access point to the second channel
  • the first channel is the working channel of the first track-side access point before the working channel of the first track-side access point changes
  • the second channel is the working channel of the second track access point.
  • the working channel of the first track access point and the working channel of the trackside access point are changed to the second channel, which can ensure the between the trackside access points.
  • the channels are the same, so that the switching efficiency can be improved when the in-vehicle access point switches between the track-side access points.
  • the method further includes:
  • the first trackside access point After the first trackside access point is disconnected from the in-vehicle access point wireless communication link, the first trackside access point changes the working channel of the first trackside access point to the first channel.
  • the first track access point When the wireless communication link between the first track access point and the vehicle access point is disconnected, the first track access point changes its own working channel to the first channel, that is, returns to the original channel, avoiding other tracks.
  • the side access points also change.
  • the first trackside access point changes the working channel of the first trackside access point to the second channel, Also includes:
  • the first trackside access point acquires the traveling direction of the vehicle carrying the vehicle access point
  • the first trackside access point queries the neighboring access point list for the identifier of the second trackside access point adjacent to the first trackside access point associated with the direction of travel of the vehicle and the second trackside access point Working channel.
  • the second aspect discloses a channel management method for a wireless local area network in rail transit, the method comprising:
  • the controller determines that the first channel is different from the second channel, where the first channel is a working channel of the first trackside access point, and the second channel is a working channel of the second trackside access point;
  • the controller instructs the first trackside access point to change the working channel to the second channel, and instructs the first trackside access point to send an indication message to instruct the in-vehicle access point to change the working channel of the in-vehicle access point to the second channel.
  • the controller when determining that the first channel and the second channel are different, instructing the working channels of the first trackside access point and the in-vehicle access point to change to the second channel, and ensuring a channel between the trackside access points The same, in order to improve the switching efficiency when the in-vehicle access point switches between the track-side access points.
  • the method further includes:
  • the controller instructs the first trackside access point to change the working channel of the first trackside access point to the first channel.
  • the controller instructs the first trackside access point to restore the working channel to the original first channel, avoiding other trackside access points. It also changes with it.
  • the controller before the first trackside access point changes the working channel to the second channel, further include:
  • the controller determines a trackside access point whose working channel is different from the preset channel as a second trackside access point
  • the controller determines the first trackside access point according to the preset condition and the driving direction of the vehicle, and the preset condition includes any one of the following: the first trackside access point is adjacent to the second trackside access point;
  • the logical distance between the first track access point and the second track access point meets a preset threshold
  • the physical distance between the first trackside access point and the second trackside access point of the first trackside access point meets a preset threshold.
  • the controller instructing the first trackside access point to change the working channel to the second channel, includes:
  • the controller instructs the first trackside access point to change the working channel to the second channel.
  • the third aspect discloses a trackside access point, including:
  • a channel changing unit configured to establish a wireless communication link between the track-side access point and the vehicle access point, and the first channel is different from the second channel, and change the working channel of the trackside access point to the second channel, One channel is the working channel of the first trackside access point, and the second channel is the working channel of the other trackside access point;
  • An indication unit instructing the in-vehicle access point to change the working channel of the in-vehicle access point to the second channel.
  • a fourth aspect discloses a controller comprising:
  • a determining unit configured to determine that the first channel is different from the second channel, where the first channel is a working channel of the first trackside access point, and the second channel is a working channel of the second trackside access point;
  • an indicating unit configured to indicate that the first trackside access point changes the working channel to the second channel, and instruct the first trackside access point to send an indication message to indicate that the in-vehicle access point changes the working channel of the in-vehicle access point to Second channel.
  • a fifth aspect discloses a trackside access point, the trackside access point comprising a processor and a communication interface,
  • a communication interface for establishing a wireless communication link with the in-vehicle access point
  • a processor configured to: if the first trackside access point and the in-vehicle access point have established a wireless communication link and the first channel is different from the second channel, change the working channel of the first trackside access point to the first
  • the second channel indicates through the communication interface that the vehicle access point changes the working channel of the vehicle access point to the second channel, and the first channel is the work of the first trackside access point before the working channel of the first trackside access point changes.
  • the second channel is the working channel of the second track access point.
  • a sixth aspect discloses a controller including a processor and a communication interface
  • a communication interface for connecting to a plurality of trackside access points and performing signaling interaction
  • a processor configured to perform determining that the first channel is different from the second channel, where the first channel is a working channel of the first trackside access point, and the second channel is a working channel of the second trackside access point;
  • the processor instructs the first trackside access point to change the working channel to the second channel, and instructs the first trackside access point to send an indication message through the communication interface to indicate that the car access point will be the car access point
  • the working channel is changed to the second channel.
  • FIG. 1 is a block diagram of a channel management system for a wireless local area network in rail transit according to an embodiment of the present invention
  • FIG. 2 is a schematic flow chart of a channel management method for a wireless local area network in rail transit according to an embodiment of the present invention
  • FIG. 3 is a schematic flow chart of another channel management method for a wireless local area network in rail transit according to an embodiment of the present invention
  • FIG. 4 is a schematic diagram of a modularization of a trackside access point according to an embodiment of the present invention.
  • FIG. 5 is a schematic diagram of a modularity of a controller according to an embodiment of the present invention.
  • FIG. 6 is a schematic structural diagram of a trackside access point according to an embodiment of the present invention.
  • FIG. 7 is a schematic structural diagram of a controller disclosed in an embodiment of the present invention.
  • FIG. 1 is a structural diagram of a channel management system for a wireless local area network in rail transit according to an embodiment of the present invention.
  • Rail transit refers to the mode of transport that runs along the track, including the use of wheeled vehicles operating on rails to transport passengers and cargo such as rail, light rail, trams, subways, and modes of transport that do not use the form of wheels but are still orbiting. Magnetic levitation, cable cars, ropeways, etc.
  • vehicles running on a track are directed by them in a directed manner.
  • Embodiments of the present invention are applicable to rail transit in which the vehicle is running on a track, the vehicle can carry one or more onboard access points, and a plurality of trackside access points are placed along the track.
  • the channel management system may further include a controller, where the controller may be a server or a network device, or may be a control center composed of multiple devices.
  • the controller is used to manage trackside access points.
  • the controller can be connected to multiple trackside access points via a wired network, a wireless network, or a hybrid network of wired and wireless.
  • multiple trackside access points can be connected to the controller through switches and routers.
  • the controller can be directly connected to each trackside access point.
  • the controller can be further connected to the in-vehicle access point via a trackside access point.
  • a trackside access point such as a trackside access point AP1, a trackside access point AP2, a trackside access point AP3, and a trackside access point are deployed at a certain distance on the ground adjacent to the track.
  • the in-vehicle access point M1 deployed on the train establishes a wireless communication link with the trackside access point.
  • the in-vehicle access point M1 transmits and receives data via a wireless communication link with the trackside access point AP2.
  • the traveling direction of the vehicle carrying the in-vehicle access point M1 is from the trackside access point AP2 to the trackside access point AP3.
  • the current working channel of the trackside access point AP3 is switched from the original channel 36 to the channel 40 due to radar signal interference, and the working channels of other trackside access points are all channels 36.
  • the in-vehicle access point M1 finds that the signal of the trackside access point AP2 is weakened, the channel 36 is scanned first to attempt to establish a wireless communication link with another trackside access point.
  • the working channel of the trackside access point AP3 is the channel 40, and the car access point M1 cannot find the trackside access point AP3.
  • the in-vehicle access point M1 continues to attempt to scan on other channels until the trackside access point AP3 is found. This process takes a lot of time, so it is difficult to quickly establish a new wireless communication link.
  • the present application proposes a channel management method for the wireless local area network in the rail transit. For details, refer to the subsequent embodiments.
  • FIG. 2 is a schematic flowchart of a channel management method for a wireless local area network in rail transit according to an embodiment of the present invention.
  • channel switching may be initiated by a first trackside access point itself.
  • the controller indicates to initiate a channel switch, and the first trackside access point may also initiate a channel switch in conjunction with the controller.
  • the method includes steps 101-102.
  • the first trackside access point and the in-vehicle access point have established a wireless communication link, and the first channel is different from the second channel, the first trackside access point accesses the first trackside The working channel of the point is changed to the second channel, and the first channel is a working channel of the first trackside access point before the working channel of the first trackside access point changes, the second channel The working channel of the access point of the second track.
  • the first trackside access point instructs the in-vehicle access point to change a working channel of the in-vehicle access point to the second channel.
  • the vehicle access point can establish a wireless communication link with the trackside access point disposed along the track, so that the passenger's device on the vehicle can access the network via the vehicle access point and the trackside access point.
  • the wireless communication link described above may be a wireless mesh link or a WDS link.
  • the working channels of all trackside access points are the same channel. Channel switching occurs because some trackside access points may be interfered by radar or other factors. If subjected to thunder A trackside access point that interferes with or interferes with other factors is indicated by the controller to switch channels, and the controller may indicate that other suitable trackside access points also switch channels.
  • the trackside access point that has performed channel switching can send the switched working channel to the trackside access point adjacent to itself.
  • the switched working channel can also be sent to the controller, which instructs the other suitable trackside access point to switch channels.
  • the vehicle access point is switched from the first track access point to the second track access point.
  • the car access point can directly Switch.
  • the car access point needs to be switched at the time of switching.
  • a scan is performed to obtain the working channel of the second track access point before the channel change can be made and switched from the first track side access point to the second track side access point.
  • the channels of the first track side access point and the second track side access point may be unified first, and then switched.
  • the first track access point can send a channel switch announcement (CSA) to the vehicle.
  • CSA channel switch announcement
  • the in-vehicle access point can change the working channel to the second channel according to the CSA.
  • the first trackside access point receives the channel change message sent by the second trackside access point or the controller, and modifies the channel according to the channel change message.
  • a working channel of the second track access point in the neighboring access point list is
  • the first trackside access point is the trackside access point AP2 in FIG. 1, and the second trackside access point is the trackside access point AP3 in FIG.
  • the first trackside access point AP2 stores a neighboring access point list in which the working channel of the adjacent access point, such as the working channel of the trackside access point AP1, is the channel 36 and the second track side.
  • the working channel of the second track access point AP3 in the point list is modified from the original channel 36 to channel 40.
  • the first trackside access point acquires a traveling direction of the vehicle carrying the in-vehicle access point.
  • the first trackside access point queries, from a list of neighboring access points, an identifier of the second trackside access point adjacent to the first trackside access point associated with a direction of travel of the vehicle And a working channel of the second track access point.
  • the first trackside access point can obtain the traveling direction of the vehicle carrying the vehicle access point by any of the following methods: First, when the first trackside access point establishes a wireless communication link with the vehicle access point, The vehicle access point actively sends the driving direction information of the vehicle to the first track side access point; secondly, when the first track side access point establishes a wireless communication link with the vehicle access point or after, the first The trackside access point sends a direction acquisition request to the vehicle access point, and the vehicle access point sends a direction response message carrying the direction information to the first trackside access point according to the request, and the first trackside access point can pass the The response message obtains the direction of travel of the vehicle.
  • the embodiments of the present invention are not limited to the above-mentioned two ways of obtaining the traveling direction of the vehicle, and may be other methods such as measurement by technical means by the trackside access point and the like.
  • the adjacent access point list may include a driving direction of the vehicle, and an identifier of an adjacent trackside access point corresponding to the driving direction, such as a media access control (MAC) address, and the adjacent track The working channel of the access point.
  • the first track access point is the trackside access point AP2
  • the traveling direction of the vehicle acquired by the trackside access point AP2 is the trackside access point AP1 to the trackside access point APn
  • the adjacent access is queried.
  • the identifier of the adjacent trackside access point corresponding to the AP1 to the trackside access point APn direction is the MAC address of the trackside access point AP3, and the working channel of the trackside access point AP3 can be known as the channel 40.
  • the first track-side access point AP2 compares its own working channel, that is, the first channel, with the second channel of the second adjacent track-side access point AP3, and determines whether the first channel and the second channel are the same. . If the first channel is channel 36 and the second channel is channel 40, the first trackside access point AP2 learns that the first channel is different from the second channel.
  • the trackside access point switches channels under the direction of the controller, the trackside access point does not need to record information for adjacent trackside access points.
  • the controller instructs the first track side access point to switch to the second channel at an appropriate timing.
  • the working channel of the first trackside access point and the working channel of the in-vehicle access point can be synchronously switched to the same channel as the working channel of the second trackside access point.
  • channel switching is required to ensure that the vehicle access point and the second trackside access point are connected before establishing a connection. For the same channel. Since the in-vehicle access point and the first track-side access point have established a wireless communication link, if the working channel of the in-vehicle access point is directly switched to the same channel as the working channel of the second access point, it may be directly The original wireless communication link between the vehicle access point and the first trackside access point is disconnected. However, the current car access point has not been able to establish a new wireless communication link with the second track access point, which may cause signal interruption.
  • the working channel of the first track access point and the working channel of the car access point can be synchronously switched to be next to the second track.
  • the working channel of the access point is the same channel to effectively reduce the probability of packet loss.
  • the trackside access point decides to switch channels autonomously, there are two ways to change the working channel.
  • the first type is changed by the first track access point, and the first track access point can directly change its working channel to the second channel and access to the second track through the wireless communication link.
  • the point transmission channel change indication is, for example, a CSA message, so that the in-vehicle access point changes its own working channel to the second channel. If the CSA message carries the switching time, the first track can be reached when the switching time is reached. The access point and the car access point make channel changes.
  • the second mode is indicated by the controller
  • the first trackside access point may send a channel change request to the controller
  • the controller receives the control change request and determines whether a channel change is needed, and if necessary, the controller may Transmitting, by the first trackside access point, a channel change indication to indicate that the first trackside access point changes the working channel of the first trackside access point to the second channel and indicates that the onboard access point will The working channel of the in-vehicle access point is changed to the second channel.
  • the vehicle access point can be used during the running of the vehicle by the following steps. Switching from the first track access point to the second track access point, the specific steps are as follows:
  • the vehicle access point finds the second track access point and detects that the signal of the second track access point is available, and the second track access point creates a new one.
  • the activated standby wireless communication link maintains the original wireless communication link with the first trackside access point, and can use the wireless communication link for data transmission and reception;
  • the standby wireless communication link may be activated to perform data transmission and reception.
  • the original wireless communication link is retained, and the original wireless communication link is only used for the in-vehicle access point to receive the buffered message sent by the first track-side access point, and cannot be used for the in-vehicle access point to access the first track.
  • Point to send data
  • the vehicle access point When the vehicle access point detects that the signal of the first track access point has weakened to a certain threshold and is difficult to use, the vehicle access point will completely disconnect the original wireless connection with the first track access point.
  • the process of switching the in-vehicle access point from the first track access point to the second track access point may not be limited to the process described above, or the in-vehicle access point may be established with the second track access point. Immediately after the new wireless communication link, the original wireless communication link established with the first trackside access point is disconnected.
  • the first trackside access point operates the first trackside access point.
  • the channel is changed to the first channel.
  • the working channel of the first track access point remains the second channel, if the first track access point is not If the working channel is restored to the original first channel, some other trackside access points may also change.
  • the working channel of the first track access point AP2 is channel 36, and the second track is connected.
  • the working channel of the ingress AP3 is the channel 40. If the first track access point AP2 changes the channel to the channel 40, if the new wireless communication link is established and the original wireless communication link is disconnected, the first will not be The working channel of the trackside access point AP2 is restored.
  • the work of the trackside access point AP1 needs to be performed according to the working channel of the trackside access point AP2.
  • the channel changes to channel 40, and thus, the working channels of multiple trackside access points may be changed to channel 40, which may cause multiple trackside access points due to changes in one trackside access point. change.
  • the working channel of the first trackside access point is restored, which can reduce the total number of channel switching in the entire system.
  • the recovery process can restore its own working channel immediately after disconnecting the original wireless communication link, or restore its working channel after the preset threshold time has elapsed.
  • the first trackside access point establishes a wireless communication link with the in-vehicle access point, and the first channel is different from the second channel, and may not be limited to the first trackside access point for status determination and determination. It can also be monitored and judged by the controller.
  • a wireless communication link may be established between the first track access point and the in-vehicle access point, and the working channel of the first track access point and the working channel of the second track access point are different.
  • the first track access point changes the working channel of its own working channel and the in-vehicle access point to the working channel of the second track access point, and ensures the first track access point through the channel change,
  • the same channel of the car access point and the second track access point so that when the car access point needs to be switched from the first track access point to the second track access point, there is no need to be next to the second track
  • the working channel of the access point is scanned, which reduces the time for acquiring the working channel of the access point of the second track, and also avoids the packet loss problem caused by channel change during the handover process, and can improve the trackside access point. The efficiency of switching between.
  • FIG. 3 is a schematic flowchart diagram of another method for channel management of a wireless local area network in rail transit according to an embodiment of the present invention.
  • the embodiment of the invention includes the flow of channel management by the controller to the trackside access point in the corresponding embodiment of FIG. 2 .
  • the method includes steps 201-202.
  • the controller determines that the first channel is different from the second channel, where the first channel is a working channel of the first trackside access point, and the second channel is a working channel of the second trackside access point.
  • the vehicle access point can establish a wireless communication link with the trackside access point disposed along the track, so that the passenger's device on the vehicle can access the network via the vehicle access point and the trackside access point.
  • the above wireless communication link may be a mesh link or a WDS link.
  • the controller and multiple trackside access points can be wired, The wireless mode or the combination of wired and wireless communication, the controller can monitor the link establishment status of multiple trackside access points and trackside access points in real time, and can also learn the information of multiple trackside access points.
  • Working channel It is assumed that the current channels of all trackside access points are initially the same channel, and the working channels of some trackside access points are switched to other channels due to interference by radar or other factors.
  • These trackside access points can notify the controller that it is subject to radar or other factors, and the controller instructs these trackside access points to switch the working channel.
  • the controller can instruct these trackside access points to switch to the same new working channel to reduce the onboard access point in these The number of channel switchings that need to be made when switching between track-side access points that are continuously set.
  • the trackside access point can also decide to switch channels independently. In this case, the trackside access point can send channel switching information to the controller.
  • the controller modifies its stored channel information according to the received channel switching information.
  • the controller can also detect each trackside access point. If a trackside access point with a channel change is found, the channel information corresponding to the trackside access point can be modified.
  • the controller determines the trackside access point whose working channel is different from the preset channel as the second trackside access point.
  • the second track access point may be a trackside access point or multiple trackside access points.
  • a trackside access point is taken as an example, and other trackside access points that generate channel changes are the same principle as the second trackside access point.
  • the controller determines the first trackside access point according to a preset condition and a driving direction of the vehicle, where the preset condition includes any one of the following: the first trackside access point and the The second track access point is adjacent to each other; the logical distance between the first track side access point and the second track side access point meets a preset threshold; the first track side access point and the The physical distance of the second track access point meets a preset threshold.
  • the controller may acquire the traveling direction of the vehicle carrying the in-vehicle access point in various ways, for example, sending a direction acquisition request to the in-vehicle access point by a trackside access point that establishes a wireless communication link with the in-vehicle access point. Obtain the direction of travel of the vehicle and inform the controller. For another example, when the vehicle access point establishes a wireless communication link by any one of the trackside access points, the traveling direction of the vehicle is notified to the trackside access point, and the controller obtains the vehicle through the trackside access point.
  • Direction of travel The embodiments of the present invention are not limited to the above-exemplified methods for obtaining the traveling direction of the vehicle, and may be other methods obtained by measurement by technical means such as trackside access points or controllers.
  • the controller selects the first trackside access point according to the second track access point, the preset selection condition, and the driving direction of the vehicle, and the preset selection condition may be based on the physical distance, the logical distance, the speed of the vehicle, and the terrain.
  • the preset selection condition can be adjusted, for example, the physical distance is increased to provide a longer time for the vehicle access point to perform channel switching.
  • the foregoing condition may be selected according to the foregoing conditions.
  • the second track access point is the track side access point AP3
  • the vehicle traveling direction is from the AP1-APn
  • the two tracks adjacent to the second track access point are adjacent to each other.
  • the ingress AP2 and the trackside access point AP4 further select AP2 as the first trackside access point according to the traveling direction of the vehicle.
  • the preset condition of determining the first track access point is the second condition, that is, the logical distance between the first track access point and the second track access point meets a preset threshold, or The three types of conditions are that the physical distance between the first track access point and the second track access point meets a preset threshold, and the first track access point may not be adjacent to the second track access point. . If the first track access point is not a trackside access point adjacent to the second track access point, then the first track All trackside access points between the side access point and the second trackside access point are also switched to the second channel along with the first trackside access point. All trackside access points between the first trackside access point and the second trackside access point may be referred to as transitional trackside access points.
  • the second track access point is the trackside access point AP3, and the first trackside access point is determined as the trackside access point AP1 according to the second type of condition and the traveling direction of the vehicle, and the transition trackside access point is It is the trackside access point AP2.
  • the controller instructs the first trackside access point to change a working channel to the second channel, and instructs the first trackside access point to send an indication message to indicate that the car access point will The working channel of the in-vehicle access point is changed to the second channel.
  • the controller may indicate that the first trackside access point is switched when the in-vehicle access point establishes a wireless communication link with the first trackside access point.
  • Working channel For example, the second track access point is the trackside access point AP3, the first trackside access point is the trackside access point AP2, and the controller finds that the first trackside access point AP2 and the car access point have been established.
  • the wireless communication link may be sent by the controller to the first trackside access point AP2 to send a channel change indication message.
  • the channel change indication message may instruct the first trackside access point AP2 to change the working channel to the second channel. Further, the channel change indication sent by the controller may further instruct the first trackside access point AP2 to send the CSA.
  • the above manner can also be applied to the first track access point determined by the second type condition or the third type condition.
  • Determining the first track access point with the second condition or the third condition allows the controller to indicate the second track access point when the vehicle access point is far from the second track access point
  • Multiple trackside access points switch the working channel together. Due to the fast speed of the vehicle, the on-board access point may have left the first track access point when these trackside access points switch the working channel. Regardless of which of the trackside access points between the first trackside access point and the second trackside access point is communicated between the onboard access point and the second trackside access point, the trackside access point can indicate the onboard access The point switches the working channel together with these trackside access points.
  • the second track access point is the trackside access point AP3, the first trackside access point is the trackside access point AP1, and the controller finds that the first trackside access point AP1 and the car access point have been established.
  • a wireless communication link wherein the controller may send a transmission channel change indication message to the first trackside access point AP1 and the transition trackside access point AP2, where the channel change indication message indicates the first trackside access point AP1 and the transition trackside access point AP2 change the working channel to the second channel.
  • the channel change indication sent by the controller may further indicate that the first track side access point AP1 and the transition track side access point AP2 send a CSA, where the indication car access point changes the working channel to the second channel. .
  • the channel change indication sent by the controller may carry the handover time, and the first trackside access point and the transition trackside access point may determine the specific moment of the channel handover according to the handover time to ensure the first track access.
  • Point, transition track access point, and vehicle access point perform work channel switching simultaneously.
  • the controller instructs the first trackside access point to be next to the first track
  • the working channel of the access point changes to the first channel
  • the controller can instruct both the first track access point and the transition track side access point to restore the working channel to the original working channel.
  • the channel recovery process can also be performed separately or simultaneously.
  • the first trackside access point and the transition trackside access point may each perform a working channel recovery within a preset time range after the wireless communication link with the in-vehicle access point is disconnected, or may be in-vehicle access. After the wireless communication link of the point and the last transition track access point is disconnected, the controller instructs the first trackside access point and the transition trackside access point to simultaneously perform working channel recovery within a preset time range.
  • the controller may instruct the preparatory trackside access point to also switch the working channel to the second channel.
  • the preparatory trackside access point is one or more trackside access points to which the vehicle is directed in a direction of travel after leaving the second track access point. in case A plurality of consecutive trackside access points are instructed to switch to the same new working channel by interference from the same interferer, and the preparatory trackside access point is the vehicle leaving the last track of the consecutive trackside access points One or more trackside access points to which the direction of travel of the vehicle behind the access point is directed.
  • the controller may instruct the preparatory trackside access point to switch the working channel while instructing the first trackside access point to switch the working channel.
  • the controller may also instruct the preparatory trackside access point to switch the working channel when the in-vehicle access point reaches a trackside access point different from the preset channel.
  • the controller may instruct the preparatory trackside access point to switch the working channel at any time after indicating that the first trackside access point switches the working channel and before the in-vehicle access point leaves the trackside access point different from the preset channel.
  • the controller instructs the preparatory trackside access point to change the working channel to the first channel, and instructs the preparatory trackside access point to send an indication message to indicate that the in-vehicle access point has its working channel Change to the first channel.
  • the controller determines that the first channel and the second channel are different, the working channel of the first track access point and the in-vehicle access point is changed to the second channel, and the first track can be ensured.
  • the channels of the side access point, the car access point and the second track access point are the same, so that when the car access point needs to be switched from the first track side access point to the second track side access point, the vehicle The access point does not need to scan the working channel of the second track access point or obtain the working channel of the second track access point through the controller, thereby reducing the time for acquiring the working channel of the second track access point, and simultaneously It also avoids the packet loss problem caused by channel change during handover, and improves the efficiency of switching between trackside access points.
  • FIG. 4 is a schematic diagram of a modularization of a trackside access point according to an embodiment of the present invention.
  • the trackside access point may include a channel changing unit 11 and an indicating unit 12.
  • the channel changing unit 11 is configured to establish a wireless communication link between the trackside access point and the in-vehicle access point, and the first channel is different from the second channel, and change the working channel of the trackside access point to In the second channel, the first channel is a working channel of the trackside access point of the trackside access point, and the second channel is a work of another trackside access point. channel;
  • the indication unit 12 is configured to instruct the in-vehicle access point to change a working channel of the in-vehicle access point to the second channel.
  • the channel changing unit 11 is further configured to: after the trackside access point is disconnected from the wireless communication link of the in-vehicle access point, change the working channel of the trackside access point to The first channel.
  • the trackside access point further includes an obtaining unit 13 and a query unit 14;
  • the acquiring unit 13 is configured to acquire a traveling direction of a vehicle carrying an in-vehicle access point by a trackside access point;
  • the query unit 14 is configured to query, by the trackside access point, the adjacent track access point adjacent to the trackside access point associated with the traveling direction of the vehicle from a list of neighboring access points The identification of the point and the working channel of the other trackside access point.
  • FIG. 5 is a schematic diagram of a modularity of a controller according to an embodiment of the present invention.
  • the controller may include a determining unit 21 and an indicating unit 22;
  • the determining unit 21 is configured to determine that the first channel is different from the second channel, where the first channel is a working channel of the first trackside access point, and the second channel is a second track access Point of work channel;
  • the indicating unit 22 is configured to instruct the first trackside access point to change a working channel to the second channel, and instruct the first trackside access point to send an indication message to indicate the vehicle access Point changing the working channel of the in-vehicle access point to the second channel.
  • the indicating unit 22 is further configured to:
  • the first trackside access point is instructed to change the working channel of the first trackside access point to The first channel.
  • the determining unit 21 is further configured to determine, as the second trackside access point, a trackside access point different from the preset channel.
  • the preset condition includes any one of the following: the first trackside access point and the second trackside access point Adjacent; a logical distance between the first trackside access point and the second trackside access point meets a preset threshold; the first trackside access point and the second trackside access point The physical distance meets the preset threshold.
  • the indicating unit 22 is specifically configured to:
  • FIG. 6 is a schematic structural diagram of a trackside access point according to an embodiment of the present invention.
  • the trackside access point includes a processor 1001 and a communication interface 1002, wherein the processor 1001 is connected to the communication interface 1002, such as through a bus 1003.
  • the processor 1001 may be a central processing unit (CPU).
  • Communication interface 1002 may be a wireless communication interface or a combination of a wireless communication interface and a wired communication interface.
  • the wireless communication interface may be, for example, a wireless local area network (WLAN) interface.
  • the wireless communication interface can also include other types of wireless interfaces, such as cellular mobile network interfaces.
  • the wired communication interface can be, for example, an Ethernet interface.
  • the Ethernet interface can be an optical interface, an electrical interface, or a combination thereof.
  • a wired communication interface and/or a wireless communication interface in communication interface 1002 can be coupled to the controller.
  • the wireless communication interface in communication interface 1002 can be used for WLAN communication with an onboard access point.
  • the trackside access point may also include a memory 1003.
  • the memory 1003 may include a volatile memory such as a random access memory (RAM); the memory may also include a non-volatile memory such as a read only memory (ROM), a flash memory, a hard disk (HDD), or a solid state disk (SSD); 1003 may also include any combination of the above types of memory.
  • the memory can be used to store a list of neighboring access points, and can also store temporarily acquired related parameters (eg, the direction of travel, speed, etc. of the vehicle). If the processor 1002 includes a CPU, the memory can also store the program code and transmit the program code to the CPU to cause the CPU to implement the embodiments of the present invention in accordance with the instructions of the program code.
  • the processor 1001 is configured to perform a wireless communication link between the orbital access point and the in-vehicle access point, and the first channel is different from the second channel, and change the working channel of the trackside access point to a second channel, where the first channel is a working channel of the trackside access point before the working channel of the trackside access point changes, and the second channel is a working channel of another trackside access point ;
  • the processor 1001 is further configured to instruct the in-vehicle access point to change a working channel of the in-vehicle access point to the second channel.
  • processor 1001 further performs:
  • the working channel of the trackside access point is changed to the first channel.
  • processor 1001 before the processor 1001 performs the step of changing the working channel of the trackside access point to the second channel, performing:
  • FIG. 7 is a schematic structural diagram of a controller according to an embodiment of the present invention.
  • the controller may be a controller, which may be a server, a network device, an access controller, or a control center composed of multiple devices.
  • the controller may include a processor 2001 and a communication interface 2002, wherein the processor 2001 is connected to the communication interface 2002, such as via a bus 2003.
  • the processor 2001 can be a CPU.
  • Communication interface 2002 can be a wired communication interface, a wireless communication interface, or a combination thereof.
  • the wired communication interface can be, for example, an Ethernet interface, and the Ethernet interface can be an optical interface, an electrical interface, or a combination thereof.
  • the wireless communication interface can be, for example, a WLAN interface, a cellular mobile network interface, or the like.
  • the communication interface 2002 can be used to connect to multiple trackside access points and perform signaling interactions.
  • the controller may also include a memory 2004.
  • Memory 2004 can include volatile memory such as RAM; memory can also include non-volatile memory such as ROM, flash memory, HDD or SSD; the memory can also include any combination of the types of memory described above.
  • the memory can be used to store a list of access points, and can also store relevant data temporarily acquired by the controller, such as the direction of travel of the vehicle. If the processor 2002 includes a CPU, the memory 2004 can also store program code and transfer the program code to the CPU to cause the CPU to implement the embodiments of the present invention in accordance with the instructions of the program code.
  • the processor 2002 is configured to perform determining that the first channel is different from the second channel, where the first channel is a working channel of the first trackside access point, and the second channel is a second track bypass The working channel of the entry point;
  • the processor 2002 is further configured to: instruct the first trackside access point to change a working channel to the second channel, and instruct the first trackside access point to send an indication message by using the communication interface. Instructing the in-vehicle access point to change a working channel of the in-vehicle access point to the second channel.
  • processor 2002 further performs:
  • the first trackside access point After the first trackside access point is disconnected from the wireless communication link of the in-vehicle access point, the first trackside access point is instructed by the first trackside access point to access the first trackside The working channel of the point is changed to the first channel.
  • the method further performs:
  • the preset condition includes any one of the following: the first trackside access point and the second trackside access point Adjacent; the first track access point and the The logical distance of the second track access point meets a preset threshold; the physical distance between the first track access point and the second track access point meets a preset threshold.
  • the processor 2002 performs to instruct the first trackside access point to change the working channel to the second channel, where:
  • the controller instructs the first trackside access point to change a working channel to the second channel.

Abstract

一种轨道交通中无线局域网的信道管理方法及相关设备。该方法包括：若第一轨旁接入点与车载接入点已建立无线通信链路且第一信道与第二信道不相同，所述第一轨旁接入点将所述第一轨旁接入点的工作信道改变为所述第二信道，所述第一信道为所述第一轨旁接入点的工作信道改变前所述第一轨旁接入点的工作信道，所述第二信道为第二轨旁接入点的工作信道；所述第一轨旁接入点指示所述车载接入点将所述车载接入点的工作信道改变为所述第二信道。

Description

一种轨道交通中无线局域网的信道管理方法及相关设备
本申请要求于2016年5月27日提交中国专利局、申请号为201610370134.1、发明名称为“一种轨道交通中无线局域网的信道管理方法及相关设备”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及通信领域，具体涉及了一种轨道交通中无线局域网的信道管理方法及相关设备。
背景技术
为满足轨道交通车辆中乘客的上网需求，可以采用无线局域网(英文：wireless local area network，WLAN)技术设置车地通信系统。在车辆上设置车载接入点(英文：access point，AP)，并沿轨道设置多个轨旁接入点。车载接入点和轨旁接入点间建立无线通信链路(如网格(英文：mesh)链路或无线分布式系统(wireless distribution system，WDS)链路)。该无线通信链路可以支持车载接入点和轨旁接入点之间的无线通信。车辆上的乘客的设备可以经由车载接入点并进一步经由轨旁接入点访问网络。车载接入点和所有轨旁接入点使用相同的信道。在车辆运行时，车载接入点在多个轨旁接入点间切换(英文：hand over)。在车辆的运行过程中，车载接入点监听轨旁接入点的信号。若车载接入点发现某个轨旁接入点的信号强度满足预设阈值时，该车载接入点可以与该轨旁接入点建立无线通信链路。车辆继续运行过程中，车载接入点发现原来与其建立无线通信链路的轨旁接入点的信号强度越来越弱，而另一轨旁接入点的信号越来越强。当另一轨旁接入点的信号强度满足预设阈值时，车载接入点可以断开原来的无线通信链路而与另一轨旁接入点建立新的无线通信链路。
轨旁接入点可能受雷达或其它信号干扰，如果轨旁接入点切换(英文：switch)到其它信道则可以避免干扰。但是切换信道后的轨旁接入点和其他轨旁接入点以及车载接入点使用的信道不同，影响无线通信链路的建立。如果轨旁接入点不切换其工作信道，干扰会影响无线通信链路的建立。进一步地，有些地方的法规规定接入点使用某些信道作为工作信道时，如果探测到雷达信号则必须切换其工作信道。因此在雷达或其它信号的干扰免会影响车载接入点在多个轨旁接入点间的切换。
发明内容
提供一种轨道交通中无线局域网的信道管理方法、设备和系统，以期确保轨旁接入点之间的信道相同。
第一方面公开了一种轨道交通中无线局域网的信道管理方法，该方法包括：
若第一轨旁接入点与车载接入点已建立无线通信链路且第一信道与第二信道不相同，第一轨旁接入点将第一轨旁接入点的工作信道改变为第二信道并指示车载接入点将车载接入点的工作信道改变为第二信道，第一信道为第一轨旁接入点的工作信道改变前第一轨旁接入点的工作信道，第二信道为第二轨旁接入点的工作信道。
在第一信道和第二信道不相同的情况下，第一轨旁接入点的工作信道和轨旁接入点的工作信道均改变为第二信道，可以确保轨旁接入点之间的信道相同，以便于车载接入点在轨旁接入点之间进行切换时能提高切换效率。
结合第一方面，在第一方面的第一种实现中，还包括：
第一轨旁接入点与车载接入点的无线通信链路断开后，第一轨旁接入点将第一轨旁接入点的工作信道改变为第一信道。
在第一轨旁接入点与车载接入点的无线通信链路断开情况下，第一轨旁接入点将自身工作信道改变为第一信道，即恢复为原来的信道，避免其它轨旁接入点也随之进行改变。
结合第一方面或第一方面的第一种实现，在第一方面的第二种实现中，第一轨旁接入点将第一轨旁接入点的工作信道改变为第二信道之前，还包括：
第一轨旁接入点获取携带车载接入点的车辆的行驶方向；
第一轨旁接入点从相邻接入点列表中查询车辆的行驶方向关联的与第一轨旁接入点相邻的第二轨旁接入点的标识和第二轨旁接入点的工作信道。
第二方面公开了一种轨道交通中无线局域网的信道管理方法，该方法包括：
控制器确定第一信道与第二信道不相同，其中，第一信道为第一轨旁接入点的工作信道，第二信道为第二轨旁接入点的工作信道；
控制器指示第一轨旁接入点将工作信道改变为第二信道，并指示第一轨旁接入点发送指示消息以指示车载接入点将车载接入点的工作信道改变为第二信道。
控制器在确定第一信道和第二信道不相同的情况下，指示第一轨旁接入点和车载接入点的工作信道改变为第二信道，可以确保轨旁接入点之间的信道相同，以便于车载接入点在轨旁接入点之间进行切换时能提高切换效率。
结合第二方面，在第二方面的第一种实现中，还包括：
第一轨旁接入点与车载接入点的无线通信链路断开后，控制器指示第一轨旁接入点将第一轨旁接入点的工作信道改变为第一信道。
在第一轨旁接入点与车载接入点的无线通信链路断开之后，控制器指示第一轨旁接入点将工作信道恢复为原来的第一信道，避免其它轨旁接入点也随之进行改变。
结合第二方面或第二方面的第一种可能的实现，在第二方面的第二种可能的实现中，控制器指示第一轨旁接入点将工作信道改变为第二信道之前，还包括：
控制器将工作信道与预设信道不同的轨旁接入点确定为第二轨旁接入点；
控制器根据预设条件和车辆的行驶方向确定第一轨旁接入点，预设条件包括如下任意一种：第一轨旁接入点与第二轨旁接入点相邻；
第一轨旁接入点与第二轨旁接入点的逻辑距离满足预设阈值；
第一轨旁接入点第一轨旁接入点与第二轨旁接入点的物理距离满足预设阈值。
结合第二方面或第二方面第二种可能的实现，在第二方面的第三种可能的实现中，控制器指示第一轨旁接入点将工作信道改变为第二信道，包括：
当第一轨旁接入点与车载接入点建立无线通信链路时，控制器指示第一轨旁接入点将工作信道改变为第二信道。
第三方面公开了一种轨旁接入点，包括：
信道变更单元，用于若轨旁接入点与车载接入点已建立无线通信链路且第一信道与第二信道不相同，将轨旁接入点的工作信道改变为第二信道，第一信道为第一轨旁接入点的工作信道改变前第一轨旁接入点的工作信道，第二信道为另一轨旁接入点的工作信道；
指示单元，指示车载接入点将车载接入点的工作信道改变为第二信道。
第四方面公开了一种控制器，包括：
确定单元，用于确定第一信道与第二信道不相同，其中，第一信道为第一轨旁接入点的工作信道，第二信道为第二轨旁接入点的工作信道；
指示单元，用于指示第一轨旁接入点将工作信道改变为第二信道，并指示第一轨旁接入点发送指示消息以指示车载接入点将车载接入点的工作信道改变为第二信道。
第五方面公开了一种轨旁接入点，轨旁接入点包括处理器和通信接口，
通信接口，用于与车载接入点建立无线通信链路；
处理器，用于执行若第一轨旁接入点与车载接入点已建立无线通信链路且第一信道与第二信道不相同，将第一轨旁接入点的工作信道改变为第二信道并通过通信接口指示车载接入点将车载接入点的工作信道改变为第二信道，第一信道为第一轨旁接入点的工作信道改变前第一轨旁接入点的工作信道，第二信道为第二轨旁接入点的工作信道。
第六方面公开了一种控制器，控制器包括处理器和通信接口，
通信接口，用于与多个轨旁接入点相连并进行信令交互；
处理器，用于执行确定第一信道与第二信道不相同，其中，第一信道为第一轨旁接入点的工作信道，第二信道为第二轨旁接入点的工作信道；
处理器，通过通信接口指示第一轨旁接入点将工作信道改变为第二信道，并通过通信接口指示第一轨旁接入点发送指示消息以指示车载接入点将车载接入点的工作信道改变为第二信道。
附图说明
为了更清楚地说明本发明实施例中的技术方案，下面将对实施例描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1是本发明实施例中一种轨道交通中无线局域网的信道管理系统的架构图；
图2是本发明实施例公开的一种轨道交通中无线局域网的信道管理方法的流程示意图；
图3是本发明实施例公开的另一种轨道交通中无线局域网的信道管理方法的流程示意图；
图4是本发明实施例公开的一种轨旁接入点的模块化示意图；
图5是本发明实施例公开的一种控制器的模块化示意图；
图6是本发明实施例公开的一种轨旁接入点的结构示意图；
图7是本发明实施例公开的一种控制器的结构示意图。
具体实施方式
请参阅图1，图1是本发明实施例中一种轨道交通中无线局域网的信道管理系统的架构图。轨道交通是指沿轨道运行的运输方式，包括用在轨道上运行的轮式车辆运输乘客和货物如铁路运输、轻轨、有轨电车、地铁以及并非使用车轮形式但仍然沿轨道运行的运输方式如磁悬浮、缆车、索道等。轨道交通中，运行在轨道上的车辆被其有向地引导。本发明实施例可应用于轨道交通中，车辆运行于轨道上，车辆可携带一个或多个车载接入点，多个轨旁接入点沿轨道安放。可选的，信道管理系统还可以包括控制器，所述控制器可以是服务器或网络设备，也可以是多个设备组成的控制中心。控制器用于管理轨旁接入点。控制器可以通过有线网络、无线网络或有线和无线的混合网络与多个轨旁接入点相连。例如，多个轨旁接入点可以通过交换机和路由器与控制器连接。又如，控制器可以直接和各个轨旁接入点相连。控制器可以通过轨旁接入点进一步连接到车载接入点。
如图1所示，在轨道旁的地面上每间隔一定距离部署一个轨旁接入点如轨旁接入点AP1、轨旁接入点AP2、轨旁接入点AP3、轨旁接入点AP4……轨旁接入点APn。列车上部署的车载接入点M1与轨旁接入点建立无线通信链路。例如，车载接入点M1经由和轨旁接入点AP2间无线通信链路收发数据。携带车载接入点M1的车辆的行驶方向为从轨旁接入点AP2行驶向轨旁接入点AP3。假设轨旁接入点AP3当前的工作信道由于受雷达信号干扰由原来的信道36切换为信道40，其它轨旁接入点的工作信道均为信道36。当车载接入点M1发现轨旁接入点AP2的信号减弱时，会先扫描信道36，以尝试和另一轨旁接入点建立无线通信链路。然而轨旁接入点AP3的工作信道为信道40，车载接入点M1无法发现轨旁接入点AP3。车载接入点M1继续尝试在其它信道上扫描，直到发现轨旁接入点AP3。此过程会耗费较多时间，因此难以快速建立新的无线通信链路。
为了改进车载接入点M1在轨旁接入点之间的切换效率，本申请提出了一种轨道交通中无线局域网的信道管理方法，具体请参见后续实施例。
请参阅图1～2，其中，图2是本发明实施例公开的一种轨道交通中无线局域网的信道管理方法的流程示意图，本发明实施例可以由第一轨旁接入点自身发起信道切换或控制器指示发起信道切换，也可以由第一轨旁接入点结合控制器来发起信道切换。所述方法包括步骤101～102。
101，若第一轨旁接入点与车载接入点已建立无线通信链路且第一信道与第二信道不相同，所述第一轨旁接入点将所述第一轨旁接入点的工作信道改变为所述第二信道，所述第一信道为所述第一轨旁接入点的工作信道改变前所述第一轨旁接入点的工作信道，所述第二信道为第二轨旁接入点的工作信道。
102，所述第一轨旁接入点指示所述车载接入点将所述车载接入点的工作信道改变为所述第二信道。
车辆在行驶过程中，车载接入点可以与沿轨道设置的轨旁接入点建立无线通信链路，以使车辆上的乘客的设备可以经由车载接入点和轨旁接入点访问网络，上述无线通信链路可以是无线网格链路也可以是WDS链路。初始时所有轨旁接入点的工作信道为同一信道。由于某些轨旁接入点可能受雷达或其它因素干扰而进行了信道切换。如果受雷 达或其它因素干扰的轨旁接入点是被控制器指示切换信道的，控制器可以指示合适的其他轨旁接入点也切换信道。如果受雷达或其它因素干扰的轨旁接入点是自主决定切换信道的，已进行信道切换的轨旁接入点可以将切换后的工作信道发送到与自己相邻的轨旁接入点，也可以将切换后的工作信道发送到控制器，由控制器指示其它合适的轨旁接入点切换信道。
车载接入点由第一轨旁接入点切换到第二轨旁接入点，当第一轨旁接入点和第二轨旁接入点为同一工作信道时，车载接入点可以直接进行切换。当第一轨旁接入点和第二轨旁接入点为不同工作信道时，由于车载接入点并不知道第二轨旁接入点的工作信道，因而在切换时车载接入点需要进行扫描以获取第二轨旁接入点的工作信道，然后才能进行信道改变以及由第一轨旁接入点切换至第二轨旁接入点。为了提高轨旁接入点之间的切换效率，可以先将第一轨旁接入点和第二轨旁接入点的信道进行统一，然后再进行切换。由于第一轨旁接入点已经获知第二轨旁接入点的工作信道即第二信道，第一轨旁接入点可以通过发送信道切换通告(英文：channel switch announcement，CSA)给车载接入点，车载接入点可以根据CSA将工作信道改变为第二信道。
如果轨旁接入点自主决定切换信道，可选的，第一轨旁接入点接收所述第二轨旁接入点或者控制器发送的信道变更消息，并根据所述信道变更消息修改所述相邻接入点列表中的所述第二轨旁接入点的工作信道。
例如，第一轨旁接入点为图1中的轨旁接入点AP2，第二轨旁接入点为图1中的轨旁接入点AP3。第一轨旁接入点AP2存储有一个相邻接入点列表，所述列表中记录有相邻接入点的工作信道如轨旁接入点AP1的工作信道为信道36和第二轨旁接入点AP3的工作信道信道36。若第二轨旁接入点AP3的工作信道由于受到雷达干扰已由信道36切换至信道40，第一轨旁接入点AP2接收信道变更消息，并根据所述信道变更消息将相邻接入点列表中的第二轨旁接入点AP3的工作信道由原来的信道36修改为信道40。
可选的，第一轨旁接入点获取携带车载接入点的车辆的行驶方向。
所述第一轨旁接入点从相邻接入点列表中查询所述车辆的行驶方向关联的与所述第一轨旁接入点相邻的所述第二轨旁接入点的标识和所述第二轨旁接入点的工作信道。
第一轨旁接入点可以通过如下任意一种方式获取携带车载接入点的车辆的行驶方向：第一种，在第一轨旁接入点与车载接入点建立无线通信链路时，由车载接入点主动向第一轨旁接入点发送车辆的行驶方向信息；第二种，在第一轨旁接入点与车载接入点建立无线通信链路时或之后，由第一轨旁接入点向车载接入点发送方向获取请求，车载接入点根据该请求向第一轨旁接入点发送的携带方向信息的方向响应消息，第一轨旁接入点可以通过该响应消息获得车辆的行驶方向。本发明实施例不局限于上述列举的两种获取车辆的行驶方向的方式，也可以是其它的如由轨旁接入点通过技术手段测量所获得等等。
相邻接入点列表中可以包括车辆的行驶方向，与行驶方向对应的相邻轨旁接入点的标识如媒体接入控制(英文：media access control，MAC)地址，以及该相邻轨旁接入点的工作信道。例如，第一轨旁接入点为轨旁接入点AP2，轨旁接入点AP2获取到的车辆的行驶方向为轨旁接入点AP1到轨旁接入点APn，查询相邻接入点列表与轨旁接入点 AP1到轨旁接入点APn方向对应的相邻轨旁接入点的标识为轨旁接入点AP3的MAC地址，进而可获知轨旁接入点AP3的工作信道为信道40。
第一轨旁接入点AP2将自身的工作信道即第一信道，与第二相邻轨旁接入点AP3的工作信道即第二信道进行比对，判断第一信道与第二信道是否相同。若第一信道为信道36，而第二信道为信道40，则第一轨旁接入点AP2获知第一信道与第二信道不相同。
如果轨旁接入点在控制器的指示下切换信道，轨旁接入点不需要记录相邻轨旁接入点的信息。控制器确定第一轨旁接入点与第二相邻轨旁接入点的工作信道不同后，在合适的时机指示第一轨旁接入点切换到第二信道。
优选的，可以将第一轨旁接入点的工作信道和车载接入点的工作信道同步切换为与第二轨旁接入点的工作信道相同的信道。
为了使车载接入点能够由第一轨旁接入点快速切换至第二轨旁接入点，需通过信道切换的方式来确保车载接入点与第二轨旁接入点在建立连接前为相同信道。由于车载接入点与所述第一轨旁接入点已建立无线通信链路，若直接将车载接入点的工作信道切换为与第二接入点的工作信道相同的信道，则可能直接断开了车载接入点与第一轨旁接入点之间的原有的无线通信链路。而当前车载接入点还未能与第二轨旁接入点建立新的无线通信链路，这样可能会导致信号中断。因此，为了保证在第一信道与第二信道不相同的情况下能够进行平滑切换，可以将第一轨旁接入点的工作信道和车载接入点的工作信道同步切换为与第二轨旁接入点的工作信道相同的信道，以有效减小丢包的概率。
如果轨旁接入点自主决定切换信道，也可以有两种改变工作信道的方式。第一种是由第一轨旁接入点进行改变，第一轨旁接入点可以直接将自身的工作信道改变为所述第二信道，并通过无线通信链路向第二轨旁接入点发送信道改变指示如CSA消息，以使所述车载接入点将自身的工作信道改变为第二信道，若CSA消息中携带有切换时间，则可以在到达切换时间时，将第一轨旁接入点和车载接入点进行信道改变。第二种方式为由控制器进行指示，第一轨旁接入点可以向控制器发送信道改变请求，控制器接收所述控制改变请求并确定是否需要进行信道改变，若需要，控制器可以向第一轨旁接入点发送信道改变指示，以指示第一轨旁接入点将所述第一轨旁接入点的工作信道改变为所述第二信道并指示所述车载接入点将所述车载接入点的工作信道改变为所述第二信道。
上述过程确保了所述第一轨旁接入点、第二轨旁接入点和所述车载接入点处于同一信道，本发明实施例可以通过下列步骤在车辆行驶过程中将车载接入点从第一轨旁接入点切换到第二轨旁接入点，具体步骤如下：
1、车辆行驶过程中，车载接入点发现所述第二轨旁接入点并检测到轨旁第二轨旁接入点的信号可用，与该第二轨旁接入点新建一个还未被激活的备用无线通信链路，同时保持与第一轨旁接入点的原来的无线通信链路，并可采用该无线通信链路进行数据收发；
2、当车载接入点监听到所述第二轨旁接入点的信号优于所述第一轨旁接入点时，可以激活所述备用无线通信链路以进行数据收发，此时仍保留原来的无线通信链路，原来的无线通信链路只用于车载接入点接收第一轨旁接入点发送的缓存报文，而不能用于车载接入点向第一轨旁接入点发送数据；
3、当车载接入点检测到所述第一轨旁接入点的信号已减弱到一定阈值而难以使用时，车载接入点会彻底断开与第一轨旁接入点的原来的无线通信链路，这时表示车载接入点已完全建立与第二轨旁接入点的无线通信链路。
车载接入点由第一轨旁接入点切换到第二轨旁接入点的过程可以不局限于上述所描述的过程，也可以是车载接入点在与第二轨旁接入点建立了新的无线通信链路后，立即断开与第一轨旁接入点建立的原来的无线通信链路。
可选的，所述第一轨旁接入点与所述车载接入点的无线通信链路断开后，所述第一轨旁接入点将所述第一轨旁接入点的工作信道改变为所述第一信道。
车载接入点建立新的无线通信链路，并断开原来的无线通信链路后，第一轨旁接入点的工作信道仍然为第二信道，若不将第一轨旁接入点的工作信道恢复为原来的第一信道，则可能会出现部分其它的轨旁接入点也随之进行改变，例如，第一轨旁接入点AP2的工作信道为信道36，第二轨旁接入点AP3的工作信道为信道40，若第一轨旁接入点AP2将信道改变为信道40，若在建立新的无线通信链路并断开原来的无线通信链路后，不将第一轨旁接入点AP2的工作信道恢复，待下一个车辆接入轨旁接入点AP1信道为信道36时，则需要根据轨旁接入点AP2的工作信道将轨旁接入点AP1的工作信道改变为信道40，由此下去，可能多个轨旁接入点的工作信道都会被改变为信道40，这会造成因一个轨旁接入点的改变而引起多个轨旁接入点的改变。第一轨旁接入点在与车载接入点断开后，将第一轨旁接入点的工作信道进行恢复，可以减少整个系统中信道切换的总次数。恢复过程可以在断开原来的无线通信链路后立即将自身的工作信道恢复，也可以在预设阈值时间到达之后，再将自身的工作信道进行恢复。
上述发明实施例中，第一轨旁接入点与车载接入点建立无线通信链路且第一信道与第二信道不相同，可以不局限于第一轨旁接入点进行状态确定和判断，也可以是由控制器进行监测和判断。
本发明实施例中，可以在第一轨旁接入点与车载接入点已建立无线通信链路且第一轨旁接入点的工作信道与第二轨旁接入点的工作信道不相同情况下，第一轨旁接入点将自身的工作信道和车载接入点的工作信道均改变为第二轨旁接入点的工作信道，通过信道改变确保了第一轨旁接入点、车载接入点和第二轨旁接入点的相同信道，这样可以在需要将车载接入点由第一轨旁接入点切换到第二轨旁接入点时，无需对第二轨旁接入点的工作信道进行扫描，减小了获取第二轨旁接入点工作信道的时间，同时也避免了切换过程中进行信道改变而引起的丢包问题，可提高轨旁接入点之间切换的效率。
请参阅图3，图3是本发明实施例公开的另一种轨道交通中无线局域网的信道管理方法的流程示意图。本发明实施例包括于图2对应实施例中采用控制器对轨旁接入点进行信道管理的流程。所述方法包括步骤201～202。
201，控制器确定第一信道与第二信道不相同，其中，所述第一信道为第一轨旁接入点的工作信道，所述第二信道为第二轨旁接入点的工作信道。
车辆在行驶过程中，车载接入点可以与沿轨道设置的轨旁接入点建立无线通信链路，以使车辆上的乘客的设备可以经由车载接入点和轨旁接入点访问网络，上述无线通信链路可以是mesh链路也可以是WDS链路。控制器与多个轨旁接入点可以采用有线方式、 无线方式或有线和无线相结合的方式进行通信连接，控制器可以实时监测到多个轨旁接入点与轨旁接入点的链路建立状态，还可以获知多个轨旁接入点的工作信道。假设初始时所有轨旁接入点的当前信道为同一信道，由于受雷达或其它因素干扰，一些轨旁接入点的工作信道切换为其它信道。这些轨旁接入点可以通知控制器自身受雷达或其它因素干扰，由控制器指示这些轨旁接入点切换工作信道。在多个连续设置的轨旁接入点受到同一干扰源(例如雷达)的干扰时，控制器可以指示这些轨旁接入点切换到相同的新的工作信道，以减少车载接入点在这些连续设置的轨旁接入点间切换时需要做的信道切换的次数。轨旁接入点也可以自主决定切换信道。这种情况下，轨旁接入点可以将信道切换信息发送给控制器。控制器根据接收到的信道切换信息修改其存储的信道信息。控制器也可以检测各个轨旁接入点，若发现有信道变更的轨旁接入点，则可以修改所述轨旁接入点对应的信道信息。
本发明实施例中，控制器将工作信道与预设信道不同的轨旁接入点确定为第二轨旁接入点。所述第二轨旁接入点可以是一个轨旁接入点，也可以是多个轨旁接入点。本发明实施例以一个轨旁接入点为例，其它产生信道变更的轨旁接入点作为第二轨旁接入点也是相同原理。
可选的，所述控制器根据预设条件和车辆的行驶方向确定所述第一轨旁接入点，所述预设条件包括如下任意一种：所述第一轨旁接入点与所述第二轨旁接入点相邻；所述第一轨旁接入点与所述第二轨旁接入点的逻辑距离满足预设阈值；所述第一轨旁接入点与所述第二轨旁接入点的物理距离满足预设阈值。
控制器可以通过多种方式获取携带车载接入点的车辆的行驶方向，例如，由与车载接入点建立无线通信链路的轨旁接入点向所述车载接入点发送方向获取请求以获取车辆的行驶方向，并告知所述控制器。又如，车载接入点在于任意一个轨旁接入点建立无线通信链路时，会将车辆的行驶方向告知给所述轨旁接入点，控制器通过该轨旁接入点获得车辆的行驶方向。本发明实施例不局限于上述所列举的获取车辆的行驶方向的方法，也可以是其它的如由轨旁接入点或控制器通过技术手段测量所获得等等。
控制器根据第二轨旁接入点、预设选择条件以及车辆的行驶方向选择第一轨旁接入点，所述预设选择条件可以是依据物理距离、逻辑距离、车辆行驶的速度以及地形等参考因素进行设定以及调整，当控制器检测到车辆行驶速度过快时，可以将预设选择条件进行调整例如增加物理距离以便于提供更长时间给车载接入点进行信道切换。
如果上述确定第一轨旁接入点的预设条件为第一类条件即所述第一轨旁接入点与所述第二轨旁接入点相邻，则可以根据上述条件选择与第二轨旁接入点相邻的两个或多个轨旁接入点，并进一步根据车辆的行驶方向从两个或多个轨旁接入点中选择一个轨旁接入点作为第一轨旁接入点。例如，如图1所示，第二轨旁接入点为轨旁接入点AP3，车辆行驶方向为从AP1-APn，则所述第二轨旁接入点相邻的两个轨旁接入点AP2和轨旁接入点AP4，进一步根据车辆的行驶方向选择AP2作为第一轨旁接入点。
如果上述确定第一轨旁接入点的预设条件为第二类条件即所述第一轨旁接入点与所述第二轨旁接入点的逻辑距离满足预设阈值，或者为第三类条件即所述第一轨旁接入点与所述第二轨旁接入点的物理距离满足预设阈值，第一轨旁接入点可以不与第二轨旁接入点相邻。如果第一轨旁接入点不是与第二轨旁接入点相邻的轨旁接入点，则第一轨 旁接入点与第二轨旁接入点之间的所有轨旁接入点也要和第一轨旁接入点一起切换到第二信道。第一轨旁接入点与第二轨旁接入点之间的所有轨旁接入点可以称为过渡轨旁接入点。例如，第二轨旁接入点为轨旁接入点AP3，根据第二类条件和车辆的行驶方向确定第一轨旁接入点为轨旁接入点AP1，则过渡轨旁接入点为轨旁接入点AP2。
202，所述控制器指示所述第一轨旁接入点将工作信道改变为所述第二信道，并指示所述第一轨旁接入点发送指示消息以指示所述车载接入点将所述车载接入点的工作信道改变为所述第二信道。
用第一类条件确定第一轨旁接入点，可以是在当车载接入点与第一轨旁接入点建立了无线通信链路时，控制器指示该第一轨旁接入点切换工作信道。例如，第二轨旁接入点为轨旁接入点AP3，第一轨旁接入点为轨旁接入点AP2，控制器发现第一轨旁接入点AP2与车载接入点已建立无线通信链路，则可以由控制器向所述第一轨旁接入点AP2发送发送信道改变指示消息。信道改变指示消息可以指示第一轨旁接入点AP2将工作信道改变为第二信道。进一步地，所述控制器所发送的信道改变指示还可以指示第一轨旁接入点AP2发送CSA。上述方式也可以适用于第二类条件或第三类条件所确定第一轨旁接入点。
用第二类条件或第三类条件确定第一轨旁接入点，可以让控制器在车载接入点离第二轨旁接入点尚远时，就指示第二轨旁接入点之前的多个轨旁接入点一起切换工作信道。由于车辆行驶速度快，这些轨旁接入点切换工作信道时车载接入点可能已经离开第一轨旁接入点。无论在工作信道切换时，车载接入点与第一轨旁接入点和第二轨旁接入点间的哪一个轨旁接入点通信，该轨旁接入点都可以指示车载接入点和这些轨旁接入点一起切换工作信道。
例如，第二轨旁接入点为轨旁接入点AP3，第一轨旁接入点为轨旁接入点AP1，控制器发现第一轨旁接入点AP1与车载接入点已建立无线通信链路，则可以由控制器向所述第一轨旁接入点AP1和过渡轨旁接入点AP2发送发送信道改变指示消息，所述信道改变指示消息指示第一轨旁接入点AP1和过渡轨旁接入点AP2将工作信道改变为第二信道。进一步地，所述控制器所发送的信道改变指示还可以指示第一轨旁接入点AP1和过渡轨旁接入点AP2发送CSA，所述指示车载接入点将工作信道改变为第二信道。
所述控制器所发送的信道改变指示可以携带切换时间，第一轨旁接入点和过渡轨旁接入点可以根据所述切换时间确定信道切换的具体时刻，以保证第一轨旁接入点、过渡轨旁接入点以及车载接入点同步执行工作信道切换。
可选的，所述第一轨旁接入点与所述车载接入点的无线通信链路断开后，所述控制器指示所述第一轨旁接入点将所述第一轨旁接入点的工作信道改变为所述第一信道。
如果存在过渡轨旁接入点，控制器可以指示第一轨旁接入点和过渡轨旁接入点都将工作信道恢复为原来的工作信道。信道恢复过程可同时也可以分别进行。例如，第一轨旁接入点和过渡轨旁接入点可以各自在与车载接入点的无线通信链路断开之后的预设时间范围内进行工作信道恢复，也可以是在车载接入点和最后一个过渡轨旁接入点的无线通信链路断开之后，控制器指示第一轨旁接入点和过渡轨旁接入点同时在预设时间范围内进行工作信道恢复。
可选的，控制器可以指示预备轨旁接入点也将工作信道切换为第二信道。预备轨旁接入点为车辆在离开第二轨旁接入点后的行驶方向指向的一个或多个轨旁接入点。如果 多个连续的轨旁接入点受到同一干扰源的干扰而被指示切换到相同的新工作信道，预备轨旁接入点为车辆在离开这些连续的轨旁接入点中的最后一个轨旁接入点后的所述车辆的行驶方向指向的一个或多个轨旁接入点。控制器可以在指示第一轨旁接入点切换工作信道的同时指示预备轨旁接入点切换工作信道。控制器也可以在车载接入点到达与预设信道不同的轨旁接入点时指示预备轨旁接入点切换工作信道。控制器可以在指示第一轨旁接入点切换工作信道后，并且在车载接入点离开与预设信道不同的轨旁接入点前的任意时刻指示预备轨旁接入点切换工作信道。在车载接入点和预备轨旁接入点建立了无线通信链路时，或在车载接入点和预备轨旁接入点建立了无线通信链路后并在车载接入点和预备轨旁接入点断开无线通信链路前，控制器指示预备轨旁接入点将工作信道改变为第一信道，并指示预备轨旁接入点发送指示消息以指示车载接入点将其工作信道改变为第一信道。
本发明实施例中，控制器在确定第一信道和第二信道不相同的情况下，指示第一轨旁接入点和车载接入点的工作信道改变为第二信道，可以确保第一轨旁接入点、车载接入点和第二轨旁接入点的信道相同，这样可以在需要将车载接入点由第一轨旁接入点切换到第二轨旁接入点时，车载接入点无需对第二轨旁接入点的工作信道进行扫描或通过控制器获取第二轨旁接入点的工作信道，减小了获取第二轨旁接入点工作信道的时间，同时也避免了切换过程中进行信道改变而引起的丢包问题，可提高轨旁接入点之间切换的效率
请参阅图4，图4是本发明实施例公开的一种轨旁接入点的模块化示意图。如图4所示，所述轨旁接入点可以包括信道变更单元11和指示单元12。
所述信道变更单元11，用于若轨旁接入点与车载接入点已建立无线通信链路且第一信道与第二信道不相同，将所述轨旁接入点的工作信道改变为所述第二信道，所述第一信道为所述轨旁接入点的工作信道改变前所述轨旁接入点的工作信道，所述第二信道为另一轨旁接入点的工作信道；
所述指示单元12，用于指示所述车载接入点将所述车载接入点的工作信道改变为所述第二信道。
可选的，所述信道变更单元11还用于：所述轨旁接入点与所述车载接入点的无线通信链路断开后，将所述轨旁接入点的工作信道改变为所述第一信道。
可选的，所述轨旁接入点还包括获取单元13和查询单元14；
所述获取单元13用于轨旁接入点获取携带车载接入点的车辆的行驶方向；
所述查询单元14用于所述轨旁接入点从相邻接入点列表中查询所述车辆的行驶方向关联的与所述轨旁接入点相邻的所述另一轨旁接入点的标识和所述另一轨旁接入点的工作信道。
本发明实施例各个单元的详细解释请参见上述方法实施例，在此不再赘述。
请参阅图5，图5是本发明实施例公开的一种控制器的模块化示意图。如图5所示，所述控制器可以包括确定单元21和指示单元22；
所述确定单元21，用于确定第一信道与第二信道不相同，其中，所述第一信道为第一轨旁接入点的工作信道，所述第二信道为第二轨旁接入点的工作信道；
所述指示单元22，用于指示所述第一轨旁接入点将工作信道改变为所述第二信道，并指示所述第一轨旁接入点发送指示消息以指示所述车载接入点将所述车载接入点的工作信道改变为所述第二信道。
可选的，所述指示单元22还用于：
所述第一轨旁接入点与所述车载接入点的无线通信链路断开后，指示所述第一轨旁接入点将所述第一轨旁接入点的工作信道改变为所述第一信道。
可选的，所述确定单元21，还用于将工作信道与预设信道不同的轨旁接入点确定为所述第二轨旁接入点；
根据预设条件和车辆的行驶方向确定所述第一轨旁接入点，所述预设条件包括如下任意一种：所述第一轨旁接入点与所述第二轨旁接入点相邻；所述第一轨旁接入点与所述第二轨旁接入点的逻辑距离满足预设阈值；所述第一轨旁接入点与所述第二轨旁接入点的物理距离满足预设阈值。
可选的，所述指示单元22具体用于：
当所述第一轨旁接入点与所述车载接入点建立无线通信链路时，指示所述第一轨旁接入点将工作信道改变为所述第二信道。
本发明实施例中的各个单元的详细解释请参考上述方法实施例，在此不再赘述。
请参阅图6，图6是本发明实施例公开的一种轨旁接入点的结构示意图。如图6所示，所述轨旁接入点包括处理器1001和通信接口1002，其中，处理器1001和通信接口1002相连，如通过总线1003相连。所述处理器1001可以是中央处理器(CPU)。通信接口1002可以是无线通信接口或者是无线通信接口和有线通信接口的组合。无线通信接口例如可以为无线局域网(英文：wireless local area network，WLAN)接口。无线通信接口还可以包括蜂窝移动网络接口等其他类型的无线接口。有线通信接口例如可以为以太网接口。以太网接口可以是光接口、电接口或其组合。通信接口1002中的有线通信接口和/或无线通信接口可以与控制器进行连接。通信接口1002中的无线通信接口可以用于与车载接入点进行WLAN通信。
所述轨旁接入点还可以包括存储器1003。存储器1003可以包括易失性存储器如随机存取存储器(RAM)；存储器还可以包括非易失性存储器如只读存储器(ROM)、快闪存储器、硬盘(HDD)或固态硬盘(SSD)；存储器1003还可以包括上述种类的存储器的任意组合。存储器可以用于存储相邻接入点列表，还可以存储临时获取的相关参数(例如车辆车辆的行驶方向、速度等)。如果处理器1002包括CPU，存储器还可以存储程序代码，并将该程序代码传输给CPU，以使得CPU根据程序代码的指示实现本发明实施例。
所述处理器1001用于执行若轨旁接入点与车载接入点已建立无线通信链路且第一信道与第二信道不相同，将所述轨旁接入点的工作信道改变为所述第二信道，所述第一信道为所述轨旁接入点的工作信道改变前所述轨旁接入点的工作信道，所述第二信道为另一轨旁接入点的工作信道；
所述处理器1001还用于指示所述车载接入点将所述车载接入点的工作信道改变为所述第二信道。
可选的，所述处理器1001还执行：
所述轨旁接入点与所述车载接入点的无线通信链路断开后，将所述轨旁接入点的工作信道改变为所述第一信道。
可选的，所述处理器1001执行将所述轨旁接入点的工作信道改变为所述第二信道的步骤之前，还执行：
获取携带车载接入点的车辆的行驶方向；
从相邻接入点列表中查询所述车辆的行驶方向关联的与所述轨旁接入点相邻的所述另一轨旁接入点的标识和所述另一轨旁接入点的工作信道。
上述发明实施例中执行步骤的具体解释请参见前面的方法实施例解释，在此不再赘述。
请参阅图7，图7是本发明实施例公开的一种控制器的结构示意图。如图7所示，所述控制器可以是控制器是可以是服务器、网络设备、接入控制器，也可以是多个设备组成的控制中心。所述控制器可以包括处理器2001和通信接口2002，其中，处理器2001和通信接口2002相连，如通过总线2003相连。所述处理器2001可以是CPU。通信接口2002可以是有线通信接口、无线通信接口或其组合。有线通信接口例如可以为以太网接口，以太网接口可以是光接口、电接口或其组合。无线通信接口例如可以为WLAN接口、蜂窝移动网络接口等。通信接口2002可以用于与多个轨旁接入点相连并进行信令交互。
所述控制器还可以包括存储器2004。存储器2004可以包括易失性存储器如RAM；存储器还可以包括非易失性存储器如ROM、快闪存储器、HDD或SSD；存储器还可以包括上述种类的存储器的任意组合。存储器可以用于存储接入点列表，还可以存储控制器临时获取的相关数据，例如车辆的行驶方向。如果处理器2002包括CPU，存储器2004还可以存储程序代码，并将该程序代码传输给CPU，以使得CPU根据程序代码的指示实现本发明实施例。
所述处理器2002，用于执行确定第一信道与第二信道不相同，其中，所述第一信道为第一轨旁接入点的工作信道，所述第二信道为第二轨旁接入点的工作信道；
所述处理器2002还用于执行指示所述第一轨旁接入点将工作信道改变为所述第二信道，并通过所述通信接口指示所述第一轨旁接入点发送指示消息以指示所述车载接入点将所述车载接入点的工作信道改变为所述第二信道。
可选的，所述处理器2002还执行：
所述第一轨旁接入点与所述车载接入点的无线通信链路断开后，通过所述通信接口2002指示所述第一轨旁接入点将所述第一轨旁接入点的工作信道改变为所述第一信道。
可选的，所述处理器2002执行指示所述第一轨旁接入点将工作信道改变为所述第二信道的步骤之前，还执行：
将工作信道与预设信道不同的轨旁接入点确定为所述第二轨旁接入点；
根据预设条件和车辆的行驶方向确定所述第一轨旁接入点，所述预设条件包括如下任意一种：所述第一轨旁接入点与所述第二轨旁接入点相邻；所述第一轨旁接入点与所 述第二轨旁接入点的逻辑距离满足预设阈值；所述第一轨旁接入点与所述第二轨旁接入点的物理距离满足预设阈值。
可选的，所述处理器2002执行指示所述第一轨旁接入点将工作信道改变为所述第二信道，具体执行：
当所述第一轨旁接入点与所述车载接入点建立无线通信链路时，所述控制器指示所述第一轨旁接入点将工作信道改变为所述第二信道。
上述发明实施例中执行步骤的具体解释请参见前面方法实施例解释，在此不再赘述。
本领域普通技术人员可以理解实现上述实施例方法中的全部或部分步骤是可以通过程序来指令处理器完成，所述的程序可以存储于计算机可读存储介质中，所述存储介质可以是随机存取存储器、只读存储器、快闪存储器、硬盘、固态硬盘、磁带，软盘，光盘或其任意组合。
以上所述，仅为本发明较佳的具体实现，但本发明的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本发明揭露的技术范围内，可轻易想到的变化或替换，都应涵盖在本发明的保护范围之内。因此，本发明的保护范围应该以权利要求的保护范围为准。

Claims (21)

  1. 一种轨道交通中无线局域网的信道管理方法，其特征在于，包括：
    若第一轨旁接入点与车载接入点已建立无线通信链路且第一信道与第二信道不相同，所述第一轨旁接入点将所述第一轨旁接入点的工作信道改变为所述第二信道并指示所述车载接入点将所述车载接入点的工作信道改变为所述第二信道，所述第一信道为所述第一轨旁接入点的工作信道改变前所述第一轨旁接入点的工作信道，所述第二信道为第二轨旁接入点的工作信道。
  2. 根据权利要求1所述的方法，其特征在于，还包括：
    所述第一轨旁接入点与所述车载接入点的无线通信链路断开后，所述第一轨旁接入点将所述第一轨旁接入点的工作信道改变为所述第一信道。
  3. 根据权利要求1或2所述的方法，其特征在于，所述第一轨旁接入点将所述第一轨旁接入点的工作信道改变为所述第二信道之前，还包括：
    第一轨旁接入点获取携带所述车载接入点的车辆的行驶方向；
    所述第一轨旁接入点从相邻接入点列表中查询所述车辆的行驶方向关联的与所述第一轨旁接入点相邻的所述第二轨旁接入点的标识和所述第二轨旁接入点的工作信道。
  4. 一种轨道交通中无线局域网的信道管理方法，其特征在于，包括：
    控制器确定第一信道与第二信道不相同，其中，所述第一信道为第一轨旁接入点的工作信道，所述第二信道为第二轨旁接入点的工作信道；
    所述控制器指示所述第一轨旁接入点将工作信道改变为所述第二信道，并指示所述第一轨旁接入点发送指示消息以指示车载接入点将所述车载接入点的工作信道改变为所述第二信道。
  5. 根据权利要求4所述的方法，其特征在于，还包括：
    所述第一轨旁接入点与所述车载接入点的无线通信链路断开后，所述控制器指示所述第一轨旁接入点将所述第一轨旁接入点的工作信道改变为所述第一信道。
  6. 根据权利要求4或5所述的方法，其特征在于，所述控制器指示所述第一轨旁接入点将工作信道改变为所述第二信道之前，还包括：
    所述控制器将工作信道与预设信道不同的轨旁接入点确定为所述第二轨旁接入点；
    所述控制器根据预设条件和车辆的行驶方向确定所述第一轨旁接入点，所述预设条件包括如下任意一种：
    所述第一轨旁接入点与所述第二轨旁接入点相邻；
    所述第一轨旁接入点与所述第二轨旁接入点的逻辑距离满足预设阈值；
    所述第一轨旁接入点与所述第二轨旁接入点的物理距离满足预设阈值。
  7. 根据权利要求4至6中任意一项所述方法，其特征在于，所述控制器指示所述第一轨旁接入点将工作信道改变为所述第二信道，包括：
    当所述第一轨旁接入点与所述车载接入点建立无线通信链路时，所述控制器指示所述第一轨旁接入点将工作信道改变为所述第二信道。
  8. 一种轨旁接入点，其特征在于，包括：
    信道变更单元，用于若轨旁接入点与车载接入点已建立无线通信链路且第一信道与第二信道不相同，将所述轨旁接入点的工作信道改变为所述第二信道，所述第一信道为所述轨旁接入点的工作信道改变前所述轨旁接入点的工作信道，所述第二信道为另一轨旁接入点的工作信道；
    指示单元，用于指示所述车载接入点将所述车载接入点的工作信道改变为所述第二信道。
  9. 根据权利要求8所述的轨旁接入点，其特征在于，所述信道变更单元，还用于：
    所述轨旁接入点与所述车载接入点的无线通信链路断开后，将所述轨旁接入点的工作信道改变为所述第一信道。
  10. 根据权利要求8或9所述的轨旁接入点，其特征在于，还包括：
    获取单元，用于获取携带所述车载接入点的车辆的行驶方向；
    查询单元，用于从相邻接入点列表中查询所述车辆的行驶方向关联的与所述轨旁接入点相邻的所述另一轨旁接入点的标识和所述另一轨旁接入点的工作信道。
  11. 一种控制器，其特征在于，包括：
    确定单元，用于确定第一信道与第二信道不相同，其中，所述第一信道为第一轨旁接入点的工作信道，所述第二信道为第二轨旁接入点的工作信道；
    指示单元，用于指示所述第一轨旁接入点将工作信道改变为所述第二信道，并指示所述第一轨旁接入点发送指示消息以指示所述车载接入点将所述车载接入点的工作信道改变为所述第二信道。
  12. 根据权利要求11所述的控制器，其特征在于，所述指示单元还用于：
    所述第一轨旁接入点与所述车载接入点的无线通信链路断开后，指示所述第一轨旁接入点将所述第一轨旁接入点的工作信道改变为所述第一信道。
  13. 根据权利要求11或12所述的控制器，其特征在于，所述确定单元还用于：
    将工作信道与预设信道不同的轨旁接入点确定为所述第二轨旁接入点；
    根据预设条件和车辆的行驶方向确定所述第一轨旁接入点，所述预设条件包括如下任意一种：
    所述第一轨旁接入点与所述第二轨旁接入点相邻；
    所述第一轨旁接入点与所述第二轨旁接入点的逻辑距离满足预设阈值；
    所述第一轨旁接入点与所述第二轨旁接入点的物理距离满足预设阈值。
  14. 根据权利要求11至13中任意一项所述的控制器，其特征在于，所述指示单元具体用于：
    当所述第一轨旁接入点与所述车载接入点建立无线通信链路时，指示所述第一轨旁接入点将工作信道改变为所述第二信道。
  15. 一种轨旁接入点，其特征在于，所述轨旁接入点包括处理器和通信接口，
    所述通信接口，用于与车载接入点建立无线通信链路；
    所述处理器，用于若轨旁接入点与所述车载接入点已建立无线通信链路且第一信道与第二信道不相同，将所述轨旁接入点的工作信道改变为所述第二信道，并通过所述通信接口指示所述车载接入点将所述车载接入点的工作信道改变为所述第二信道，所述第一信道为所述轨旁接入点的工作信道改变前所述轨旁接入点的工作信道，所述第二信道为另一轨旁接入点的工作信道。
  16. 根据权利要求15所述的轨旁接入点，其特征在于，所述处理器还用于：
    所述轨旁接入点与所述车载接入点的无线通信链路断开后，将所述轨旁接入点的工作信道改变为所述第一信道。
  17. 根据权利要求15或16所述的轨旁接入点，其特征在于，所述处理器将所述轨旁接入点的工作信道改变为所述第二信道之前，所述处理器还用于：
    获取携带所述车载接入点的车辆的行驶方向；
    从相邻接入点列表中查询所述车辆的行驶方向关联的与所述轨旁接入点相邻的所述另一个轨旁接入点的标识和所述另一个轨旁接入点的工作信道。
  18. 一种控制器，其特征在于，所述控制器包括处理器和通信接口，
    所述通信接口，用于与多个轨旁接入点相连并进行信令交互；
    所述处理器，用于执行确定第一信道与第二信道不相同，其中，所述第一信道为第一轨旁接入点的工作信道，所述第二信道为第二轨旁接入点的工作信道；
    所述处理器，还用于通过所述通信接口指示所述第一轨旁接入点将工作信道改变为所述第二信道，以及指示所述第一轨旁接入点发送指示消息以指示车载接入点将所述车载接入点的工作信道改变为所述第二信道。
  19. 根据权利要求18所述的控制器，其特征在于，所述处理器还用于：
    所述第一轨旁接入点与所述车载接入点的无线通信链路断开后，通过所述通信接口指示所述第一轨旁接入点将所述第一轨旁接入点的工作信道改变为所述第一信道。
  20. 根据权利要求18或19所述的控制器，其特征在于，所述指示所述第一轨旁接入点将工作信道改变为所述第二信道之前，所述处理器还用于：
    将工作信道与预设信道不同的轨旁接入点确定为所述第二轨旁接入点；
    根据预设条件和车辆的行驶方向确定所述第一轨旁接入点，所述预设条件包括如下任意一种：
    所述第一轨旁接入点与所述第二轨旁接入点相邻；
    所述第一轨旁接入点与所述第二轨旁接入点的逻辑距离满足预设阈值；
    所述第一轨旁接入点与所述第二轨旁接入点的物理距离满足预设阈值。
  21. 根据权利要求18至20中任意一项所述的控制器，其特征在于，所述处理器还用于：
    当所述第一轨旁接入点与所述车载接入点建立无线通信链路时，指示所述第一轨旁接入点将工作信道改变为所述第二信道。
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