WO2019020004A1 - 切换接入点的方法、控制器、网络设备和存储介质 - Google Patents

切换接入点的方法、控制器、网络设备和存储介质 Download PDF

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Publication number
WO2019020004A1
WO2019020004A1 PCT/CN2018/096795 CN2018096795W WO2019020004A1 WO 2019020004 A1 WO2019020004 A1 WO 2019020004A1 CN 2018096795 W CN2018096795 W CN 2018096795W WO 2019020004 A1 WO2019020004 A1 WO 2019020004A1
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Prior art keywords
terminal
rtt
rtts
reference value
switching
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PCT/CN2018/096795
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English (en)
French (fr)
Inventor
王瑞丰
王云贵
孙福清
何志健
潘淳
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华为技术有限公司
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Publication of WO2019020004A1 publication Critical patent/WO2019020004A1/zh

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/0005—Control or signalling for completing the hand-off
    • H04W36/0083—Determination of parameters used for hand-off, e.g. generation or modification of neighbour cell lists
    • H04W36/00837—Determination of triggering parameters for hand-off
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W48/00—Access restriction; Network selection; Access point selection
    • H04W48/16—Discovering, processing access restriction or access information
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W64/00—Locating users or terminals or network equipment for network management purposes, e.g. mobility management
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/08—Reselecting an access point
    • 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
    • H04W36/30—Reselection being triggered by specific parameters by measured or perceived connection quality data
    • H04W36/302—Reselection being triggered by specific parameters by measured or perceived connection quality data due to low signal strength

Definitions

  • the present application relates to the field of communications, and in particular, to a method, a controller, a network device, and a computer readable storage medium for switching an access point.
  • WLAN wireless local area network
  • the coverage radius of a wireless local area network is usually 20 m (m) to 30 m indoors and 100 m outdoor. If a high-gain directional antenna is used, the coverage radius of the WLAN can be increased to more than 600m. Therefore, WLANs can be deployed on WLAN devices that can use high-gain directional antennas on highways.
  • FIG 1 is a schematic diagram of a highway WLAN system.
  • the WLAN access point (English: access point, AP) is placed on the roadside of the highway, such as AP1, AP2, and AP3.
  • the user uses a terminal in the car, such as a mobile phone.
  • the handset is connected to the AP on the roadside, accessing the Internet via the AP and further via a wired network device such as a switch or router.
  • the terminal moves in a high-speed car as the vehicle moves at a high speed.
  • the terminal quickly switches between APs.
  • the terminal handover means that when the terminal moves from the coverage area of one AP to the coverage area of another AP, the terminal disconnects from the source AP and connects with the destination AP.
  • the real-time distance is calculated based on the round-trip time (RTT) of the AP and the terminal.
  • RTT round-trip time
  • the AP sends a probe packet including the data null frame to the terminal through the air interface, and records the duration between sending the probe packet and receiving the acknowledgement (ACK) frame as the round trip time.
  • the real-time distance between the AP and the terminal can be calculated according to formula (1):
  • C is the speed of light and D is the real-time distance between the AP and the terminal.
  • the RTT calculated according to the above method is larger than the duration of the probe packet from the AP to the terminal.
  • the present application provides a method, controller, network device, and computer readable storage medium for switching access points, and to switch access points at the same time.
  • a method for switching an access point comprising:
  • the controller determines the RTT reference value based on the minimum of the plurality of RTTs of the terminal. If the switching condition based on the difference between the real-time RTT and the RTT reference value is satisfied, the controller instructs the AP currently connected by the terminal to send a channel switching announcement to the terminal. The channel switching announcement instructs the terminal to switch the working channel to the working channel of the next AP.
  • the reference value is determined according to the minimum value of the plurality of RTTs of the terminal, and the reference value is the RTT measured when the physical distance between the terminal and the AP is closest, and may represent the processing time of the physical device chip.
  • the difference between the RTT and the RTT reference value of the terminal in the real-time position, that is, the influence of different physical devices on the RTT is excluded.
  • the AP currently connected to the terminal is sent a channel switching announcement to the terminal, so that the terminal can switch the working channel to the working channel of the next AP in time.
  • the controller determines an RTT reference value according to a minimum value of the plurality of RTTs of the terminal, including: the controller is configured according to the terminal A plurality of RTTs calculate a plurality of RTT averages, and a minimum of the plurality of RTT averages is determined as an RTT reference value.
  • the minimum value of the RTT mean is determined as the RTT reference value, and the purpose of calculating the RTT mean is to reduce the influence of the abnormal RTT on determining the RTT reference value.
  • the multiple RTTs of the terminal include the measured by the multiple APs and the terminal Multiple RTTs.
  • a plurality of RTTs between a plurality of APs and a terminal have more sampling data of the RTT, thereby determining an RTT reference value in a larger range, and improving the accuracy of the RTT reference value.
  • the handover AP success rate is less than the preset handover success rate
  • multiple of the terminal The RTT only includes a plurality of RTTs measured by the AP currently connected by the terminal and the terminal.
  • a second aspect of the present application provides a controller comprising means for performing the steps of the method of any of the above-described first aspect or any of the possible implementations of the first aspect.
  • a third aspect of the present application provides a network device, the network device including a processor and a port,
  • the processor is used to:
  • the port is used to indicate that the AP currently connected by the terminal sends a channel switching announcement to the terminal, where the channel switching announcement indicates that the terminal will The working channel is switched to the working channel of the next AP.
  • the processor is configured to calculate a plurality of RTT average values according to the multiple RTTs of the terminal, and select a minimum value of the plurality of RTT averages Determined as the reference value.
  • the multiple RTTs of the terminal include multiple RTTs that are measured by multiple APs and the terminal.
  • the multiple RTTs of the terminal when the handover AP success rate is less than the preset handover success rate, the multiple RTTs of the terminal only include the AP measured by the terminal currently connected to the terminal and the terminal Multiple RTTs between.
  • a fourth aspect of the present application provides a computer readable storage medium having stored therein instructions that, when executed on a computer, cause the computer to perform the methods described in the above aspects or implementations.
  • a fifth aspect of the present application provides a computer program product comprising instructions which, when run on a computer, cause the computer to perform the methods described in the above aspects or implementations.
  • Figure 1 is a schematic diagram of a highway WLAN system
  • FIG. 2 is a schematic flowchart of a method for switching an access point in an embodiment of the present invention
  • FIG. 3 is a schematic diagram of roadside deployment of an AP in an embodiment of the present invention.
  • FIG. 4 is a schematic diagram of signaling interaction for acquiring a terminal RTT reference value in an embodiment of the present invention
  • FIG. 5 is a schematic diagram of the principle of the RTT
  • Figure 6 is a schematic diagram of switching based on real-time distance
  • FIG. 7 is a schematic diagram of signaling interaction for acquiring a terminal RTT reference value in an embodiment of the present invention.
  • FIG. 8 is a schematic structural diagram of a controller in an embodiment of the present invention.
  • FIG. 9 is a schematic structural diagram of a network device according to an embodiment of the present invention.
  • FIG. 2 is a schematic flowchart of a method for switching an access point according to an embodiment of the present invention. This method can be used in systems including APs and controllers. The method includes the following steps.
  • the controller determines an RTT reference value according to a minimum value of the plurality of RTTs of the terminal.
  • BSSID basic service set identifier
  • the terminal associates with the AP to join the basic service set (BSS) identified by the BSSID.
  • BSS basic service set
  • the traditional handover of the terminal between APs changes the BSS where the terminal is located. Accordingly, the terminal requests a BSS whose associated BSSID is different from the BSSID of the BSS associated with the handover.
  • the terminal In the highway scene, the terminal is in the vehicle. Vehicles on highways are generally moving at high speeds. If the AP associated with the terminal is switched in the conventional manner, the terminal may associate the next AP shortly after being associated with one AP, thereby frequently switching between the APs. In order for the terminal not to perceive the occurrence of the handover, the change of the BSSID is to be avoided.
  • the BSSID used by the old AP to provide the service for the terminal is simulated. This process can be seen as the BSSID moving following the movement of the terminal.
  • an AP that simulates a corresponding BSSID serving a terminal is referred to as an AP connected to the terminal.
  • multiple APs provide the same BSSID.
  • the terminal joins the BSS identified by the BSSID instead of being associated with a specific AP.
  • Neighboring APs generally use different working channels (English: operating channel).
  • the AP connected to the terminal uses the Channel Switch Announcement (CSA) to instruct the terminal to switch the working channel to the working channel of the next AP, so that the terminal switches between the APs.
  • CSA Channel Switch Announcement
  • the AP connected to the terminal sends an RTT probe packet.
  • the RTT probe message is, for example, an empty data frame.
  • the receiver address of the RTT probe packet (English: receiver address) is the media access control (MAC) address of the terminal.
  • the AP may periodically send an RTT probe message to each terminal connected to the AP.
  • the period for sending an RTT probe packet is 200 milliseconds, that is, 5 times of RTT probe packets are sent to a single terminal every second.
  • the AP can also send probe packets non-periodically.
  • the AP sends the RTT to the controller connected to the AP, and the controller can determine the RTT reference value according to the minimum value among the plurality of RTTs of the terminal.
  • FIG. 3 is a schematic diagram of roadside deployment of an AP in an embodiment of the present invention.
  • the terminal connected to AP1 moves from position A to position A1, and the terminal connected to AP1 moves from position A1 to position A2.
  • the value of the RTT is gradually reduced from a large value to a minimum value, and then gradually increased from the minimum value. That is, the RTT of the terminal connected to AP1 at location A is greater than the RTT of the terminal at location A1, and the RTT of the terminal at location A1 is less than the RTT of the terminal at location A2.
  • the terminal connected to AP1 is at the position A1 closest to AP1, the RTT of the terminal and AP1 is the smallest.
  • the RTT closest to the minimum value of RTT is called the RTT reference value.
  • the RTT reference value is the RTT measured when the physical distance between the terminal and the AP is closest, and can represent the processing time of the physical device chip.
  • the controller may select a minimum value among the plurality of RTTs of the terminal, and use the minimum value as the RTT reference value. This ensures the accuracy of the RTT reference.
  • the controller may further calculate a plurality of RTT average values according to the plurality of RTTs of the terminal, determine a minimum value among the plurality of RTT average values, and use the minimum value as the RTT reference value.
  • the purpose of calculating the RTT mean is to reduce the effect of abnormal RTT on determining the RTT reference value.
  • the controller can also calculate the RTT mean within a specified period based on the plurality of RTTs of the terminal.
  • the specified period can be set in advance according to actual needs. As an example, the specified period is 1 hour, the controller can calculate the average RTT value within 1 hour according to multiple RTTs of the terminal, then the corresponding RTT mean value is obtained every hour, and the corresponding RTT mean value is selected in each hour. The minimum value is then used as the RTT reference value.
  • the terminal has an RTT minimum when it is connected to each AP.
  • the AP models are identical.
  • the minimum RTT is equal when connected to each AP.
  • FIG. 4 is a schematic diagram of signaling interaction for acquiring an RTT reference value according to an embodiment of the present invention.
  • the terminal is connected to the AP, and the AP reports the event to the controller.
  • the AP periodically sends an RTT detection message to the terminal, and the RPT reports the RTT to the controller every time the RPT is obtained.
  • the controller selects the minimum value of the RTT from the plurality of RTTs, and determines the minimum value as the RTT reference value.
  • the controller may determine the RTT reference value according to a minimum value among the plurality of RTTs when the terminal is connected to the plurality of APs.
  • the terminal is connected and disconnected with multiple APs in sequence, and then there are multiple RTTs for each AP, and multiple APs measure multiple RTTs with the terminal, and determine the RTT reference value based on the multiple RTTs to improve the RTT reference value.
  • the accuracy is a measure of the RTT reference value based on the multiple RTTs.
  • the models of the APs connected to the terminal may be the same or different.
  • the RTT is also different. Then, the RTT reference value corresponding to the AP can be determined for each AP.
  • the controller can determine the RTT reference value based on the minimum value in the RTT when connected to each AP. Specifically, when the terminal is connected to each AP, there are a plurality of RTTs, and the minimum value among the plurality of RTTs is determined as the RTT reference value. In other words, the RTT reference value varies depending on the AP.
  • the RTT reference value corresponding to the AP can be determined, which can improve the pertinence and accuracy of the RTT reference value.
  • the multiple RTTs of the terminal only include the APs currently connected by the terminal to measure multiple RTTs with the terminal.
  • AP1, AP2, ..., AP10, AP11, and AP12 are sequentially arranged on the highway side, and the terminal sequentially travels from AP1 to AP12, and the terminal sequentially connects AP1, AP2, ..., AP12.
  • the handover AP success rate is less than the preset handover success rate.
  • the controller relinquishes multiple RTTs when the AP1 to AP10 connected to the terminal are connected.
  • the controller can determine the RTT reference value based on the minimum of the plurality of RTTs when connected to the AP 10 to improve the accuracy of the RTT reference value.
  • the above three options can be selected according to the actual situation. That is to say, multiple of the above three schemes can be simultaneously executed.
  • the controller is configured to indicate that the AP currently connected by the terminal sends a channel switching announcement to the terminal, where the channel switching announcement instructs the terminal to switch the working channel to the next AP. channel.
  • the RTT time collected by the AP is 2 (T1+T2) of the baseband chip processing time more than the real RTT time.
  • 2 (T1+T2) is called the RTT reference value (English: RTT base value, RTT-BASE).
  • T1 is related to the chip used by the AP
  • T2 is related to the chip used by the terminal, because it is a round trip delay, so it is 2 times (T1+T2). So the RTT-BASE values for a given pair of APs and terminals are fixed.
  • b is the terminal RTT-BASE value
  • L is the real-time distance between the AP currently connected to the terminal and the terminal.
  • the real RTT is the actual round trip delay between the AP currently connected to the terminal and the terminal.
  • the difference between the real-time RTT and the RTT reference value is the real RTT.
  • the real RTT satisfies the switching condition.
  • the controller instructs the AP currently connected to the terminal to send a channel switching announcement to the terminal.
  • the channel switching announcement instructs the terminal to switch the working channel to the working channel of the next AP. .
  • FIG. 6 is a schematic diagram of switching based on real-time distance.
  • the terminal gradually approaches AP1, and the real-time distance of the terminal can know whether the terminal enters the handover area.
  • the switching area is determined by a preset minimum switching threshold and a preset maximum switching threshold.
  • the terminal does not enter the switching area.
  • the terminal enters the handover area.
  • the controller determines that the handover condition is met, and the controller instructs the AP currently connected by the terminal to send a channel switching announcement to the terminal.
  • the real-time distance between the currently connected AP and the terminal can be calculated.
  • the switching condition is greater than a preset minimum switching threshold.
  • the real-time distance between the currently connected AP and the terminal is greater than a preset minimum handover threshold, and the controller instructs the AP currently connected by the terminal to send a channel switching announcement to the terminal.
  • the switching condition is greater than a preset RTT threshold.
  • the switching area in FIG. 6 may be determined by a preset minimum RTT threshold and a preset maximum RTT threshold.
  • the real RTT is greater than the preset minimum RTT threshold, and the controller instructs the AP currently connected by the terminal to send a channel switching announcement to the terminal.
  • the handover condition may also take into account the Received Signal Strength Indication (RSSI), and a preset maximum handover threshold and a preset minimum handover threshold.
  • RSSI Received Signal Strength Indication
  • the real-time distance between the currently connected AP and the terminal can be calculated, and the real-time distance between the currently connected AP and the terminal is greater than a preset minimum handover threshold and less than a preset maximum handover threshold, and the RSSI is less than
  • the RSSI threshold is used by the controller to indicate that the AP currently connected by the terminal sends a channel switching announcement to the terminal.
  • the switching condition considers the RSSI, as well as a preset maximum RTT threshold and a preset minimum RTT threshold.
  • the real RTT is greater than the preset maximum RTT threshold and less than the preset minimum RTT threshold, and the RSSI is less than the RSSI threshold, and the controller instructs the currently connected AP to send the channel to the terminal. Switch the announcement.
  • the controller indicates that the AP currently connected by the terminal sends a channel switching announcement to the terminal.
  • the controller determines the RTT reference value according to the minimum value among the plurality of RTTs of the terminal, and can ensure that the error of the RTT reference value is small. If the switching condition based on the difference between the real-time RTT and the RTT reference value is met, the controller is configured to indicate that the AP currently connected by the terminal sends a channel switching announcement to the terminal, and the channel switching announcement instructs the terminal to switch the working channel to the working channel of the next AP. Thereby ensuring that the terminal communicates through the AP.
  • FIG. 7 is a schematic diagram of signaling interaction for acquiring a reference value of a terminal RTT according to an embodiment of the present invention, which specifically includes:
  • AP1 sends an RTT probe packet to the terminal, and the terminal replies with an ACK packet to AP1.
  • the AP1 reports the terminal RTT reference value to the controller.
  • the controller determines the difference between the real-time RTT and the RTT reference value based on the reported terminal RTT reference value.
  • the switching condition is satisfied, and the controller sends a channel switching announcement to the terminal through AP1.
  • the terminal is switched from the working channel of AP1 to the working channel of AP2, and AP2 sends a feedback result feedback to the controller.
  • FIG. 8 is a schematic structural diagram of a controller according to an embodiment of the present invention, which specifically includes: a calculation module 801 and a sending module 802. For the function of each module, refer to the above steps.
  • FIG. 9 is a schematic structural diagram of a network device according to an embodiment of the present invention, including a processor 901 and a port 902, for implementing a method for switching an access point.
  • the network device further includes a memory 903.
  • the processor 901, the port 902, and the memory 903 are connected to each other, for example, by a bus.
  • the processor 901 can be a central processing unit (CPU).
  • Port 902 can be a wireless port or a wired port.
  • the wireless port may be a cellular mobile network port, a WLAN port, or the like.
  • the wired port can be an Ethernet port, such as an optical port or an electrical port.
  • the memory 903 may be a read only memory (ROM) or a random access memory (RAM), a magnetic memory or the like.
  • the processor 901 determines an RTT reference value according to a minimum value of the plurality of RTTs of the terminal; if the switching condition based on the difference between the real-time RTT and the RTT reference value is satisfied, the port 902 is used to indicate that the AP currently connected by the terminal sends a channel switch to the terminal. It is announced that the channel switching announcement instructs the terminal to switch the working channel to the working channel of the next AP.
  • processor 901 For specific processing details of the processor 901, refer to the corresponding embodiments of FIGS. 2 to 8.
  • the computer program product comprises one or more computer instructions.
  • the computer program instructions When the computer program instructions are loaded or executed on a computer, the processes or functions described in accordance with embodiments of the present invention are generated in whole or in part.
  • the computer can be a general purpose computer, a special purpose computer, a computer network, or other programmable device.
  • the computer instructions can be stored in a computer readable storage medium or transferred from one computer readable storage medium to another computer readable storage medium, for example, the computer instructions can be from a website site, computer, server or data center Transfer to another website site, computer, server, or data center by wire (eg, coaxial cable, twisted pair, fiber optic) or wireless (eg, infrared, wireless, microwave, etc.).
  • the computer readable storage medium can be any medium that can be accessed by a computer or a data storage device that includes one or more media integrated servers, data centers, and the like.
  • the medium may be a magnetic medium (eg, a floppy disk, a hard disk, a magnetic tape), an optical medium (eg, an optical disk), or a semiconductor medium (such as a solid state disk (SSD)) or the like.

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Abstract

一种切换接入点的方法、控制器、网络设备和计算机可读存储介质，所述方法包括：控制器依据终端的多个往返时延(RTT)中的最小值，确定RTT基准值；如果基于实时RTT和所述RTT基准值的差值的切换条件被满足，所述控制器指示所述终端当前连接的接入点(AP)向所述终端发送信道切换宣告，所述信道切换宣告指示所述终端将工作信道切换为下一个AP的工作信道。采用本发明实施例后，在提高RTT基准值准确性的基础上，终端可以及时切换接入点。

Description

切换接入点的方法、控制器、网络设备和存储介质
本申请要求于2017年7月26日提交中国专利局、申请号为201710617820.9、发明名称为“切换接入点的方法、控制器、网络设备和存储介质”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，尤其涉及一种切换接入点的方法、控制器、网络设备和计算机可读存储介质。
背景技术
无线局域网(英文：wireless local area network，WLAN)的覆盖半径通常为室内20米(m)～30m，室外约100m。如果采用高增益的定向天线，可将WLAN的覆盖半径提高到600m以上。因此在高速公路可以采用高增益的定向天线的WLAN设备部署WLAN。
参见图1，图1是高速公路WLAN系统示意图。WLAN的接入点(英文：access point，AP)布放在高速公路的路旁，如：AP1、AP2和AP3。用户在汽车内使用终端，如手机。手机连接到路旁的AP，经由AP并进一步经由有线网络设备(例如交换机或路由器)访问互联网。
终端在高速行驶的汽车内，随着车辆高速移动。终端在AP间快速切换。终端切换是指：当终端从一个AP的覆盖区域移动到另外一个AP的覆盖区域时，终端断开与源AP连接，并与目的AP连接。
在切换AP的过程中，需要确定终端与AP的实时距离。实时距离是依据AP与终端的往返时延(英文：round-trip time，RTT)计算的。
AP通过空口向终端发送包括数据空帧的探测报文，并记录从发送探测报文到收到确认(ACK)帧之间的时长以作为往返时间。AP与终端的实时距离可以按照公式(1)计算：
D＝RTT*C/2                (1)
其中，C为光速，D为AP与终端的实时距离。
按照上述方法计算得到的RTT比探测报文从AP到终端的时长偏大。
由于RTT存在较大误差，因此无法及时切换接入点。
发明内容
本申请提供了一种切换接入点的方法、控制器、网络设备和计算机可读存储介质，以及时切换接入点。
第一方面，提供一种切换接入点的方法，所述方法包括：
控制器依据终端的多个RTT中的最小值，确定RTT基准值。如果基于实时RTT和所述RTT基准值的差值的切换条件被满足，所述控制器指示所述终端当前连接的AP向所述终端发送信道切换宣告。所述信道切换宣告指示所述终端将工作信道切换为下一 个AP的工作信道。
在上述技术方案中，依据终端的多个RTT中的最小值确定基准值，基准值是终端与AP之间的物理距离最近时测量得到的RTT，可以代表物理器件芯片的处理时间。终端处于实时位置的RTT与RTT基准值的差值，即排除了不同物理器件对RTT的影响。满足切换条件，则指示终端当前连接的AP向终端发送信道切换宣告，以使终端及时将工作信道切换为下一个AP的工作信道。
结合第一方面，在第一方面的第一种可能的实现方式中，控制器依据终端的多个RTT中的最小值，确定RTT基准值，包括：所述控制器依据所述终端的所述多个RTT计算多个RTT均值，将所述多个RTT均值中的最小值确定为RTT基准值。
在上述技术方案中，将RTT均值中的最小值确定为RTT基准值，计算RTT均值的目的在于减少异常RTT对确定RTT基准值的影响。
结合第一方面或第一方面的第一种可能的实现方式，在第一方面的第二种可能的实现方式中，所述终端的多个RTT包括多个AP测量到的与所述终端间的多个RTT。
在上述技术方案中，多个AP与终端间的多个RTT，RTT的采样数据较多，从而在较大范围内确定RTT基准值，提高RTT基准值的准确性。
结合第一方面或第一方面的第一种可能的实现方式，在第一方面的第三种可能的实现方式中，在切换AP成功率小于预设切换成功率时，所述终端的多个RTT只包括所述终端当前连接的AP测量到的与所述终端间的多个RTT。
在上述技术方案中，在切换AP成功率小于预设切换成功率时，则说明RTT的准确性较差，因此在确定RTT基准值时，则需要放弃之前获得的RTT，以提高RTT基准值的准确性。
本申请的第二方面提供了一种控制器，包括执行上述第一方面或第一方面的任一可能的实现方式的方法中步骤的模块。
本申请的第三方面提供了一种网络设备，所述网络设备包括处理器和端口，
所述处理器用于：
依据终端的多个RTT中的最小值，确定RTT基准值；
如果基于实时RTT和所述RTT基准值的差值的切换条件被满足，用所述端口指示所述终端当前连接的AP向所述终端发送信道切换宣告，所述信道切换宣告指示所述终端将工作信道切换为下一个AP的工作信道。
结合第三方面，在第一种可能的实现方式中，所述处理器，具体用于依据所述终端的所述多个RTT计算多个RTT均值，将所述多个RTT均值中的最小值确定为所述基准值。
在第三方面或上述任一可能的实现方式中，所述终端的多个RTT包括多个AP测量到的与所述终端间的多个RTT。
在第三方面或上述任一可能的实现方式中，在切换AP成功率小于预设切换成功率时，所述终端的多个RTT只包括所述终端当前连接的AP测量到的与所述终端间的多个RTT。
本申请的第四方面提供了一种计算机可读存储介质，所述计算机可读存储介质中存储有指令，当其在计算机上运行时，使得计算机执行上述各方面或实现方式所述的方 法。
本申请的第五方面提供了一种包含指令的计算机程序产品，当其在计算机上运行时，使得计算机执行上述各方面或实现方式所述的方法。
附图说明
图1是高速公路WLAN系统示意图；
图2是本发明实施例中切换接入点的方法流程示意图；
图3是本发明实施例中AP的路旁部署示意图；
图4是本发明实施例中获取终端RTT基准值的信令交互示意图；
图5是RTT的原理示意图；
图6是以实时距离为依据的切换示意图；
图7是本发明实施例中获取终端RTT基准值的信令交互示意图；
图8是本发明实施例中控制器的结构示意图；
图9是本发明实施例中网络设备的结构示意图。
具体实施方式
参见图2，图2是本发明实施例中切换接入点的方法流程示意图。该方法可以在包括AP和控制器的系统中使用。该方法包括以下步骤。
S201、控制器依据终端的多个RTT中的最小值，确定RTT基准值。
传统的AP提供独立的基本服务集标识(英文：basic service set identifier，BSSID)。终端和该AP关联即加入该BSSID所标识的基本服务集(英文：basic service set，BSS)。终端在AP间的传统切换要改变终端所在的BSS。相应地，终端会请求关联BSSID与切换前关联的BSS的BSSID不同的BSS。
高速公路场景中终端在交通工具中。高速公路上的交通工具一般处于高速移动状态。如果采用传统的方式切换终端所关联的AP，终端可能在与一个AP之后不久就要关联下一个AP，从而在AP之间频繁切换。为使终端不感知到切换的发生，要避免BSSID的改变。本发明实施例中，新的AP为终端提供服务时，模拟旧的AP为终端提供服务时使用的BSSID。该过程可以看作BSSID跟随终端的移动而移动。以下将模拟相应BSSID为终端提供服务的AP称为与终端连接的AP。
上述方案中，多个AP提供相同的BSSID。在关联后，终端加入该BSSID所标识的BSS，而不是和特定的AP关联。相邻AP一般使用不同的工作信道(英文：operating channel)。与终端连接的AP用信道切换宣告(英文：Channel Switch Announcement，CSA)指示终端将工作信道切换为下一个AP的工作信道，从而使终端在AP间切换。
与终端连接的AP发送RTT探测报文。RTT探测报文例如为空数据帧。RTT探测报文的接收方地址(英文：receiver address)为终端的介质访问控制(MAC)地址。
AP可以为每个连接该AP的终端周期性地发送RTT探测报文。例如，发送RTT探测报文的周期是200毫秒，即每秒向单个终端发送5次RTT探测报文。AP也可以非周期性地发送探测报文。
AP将RTT发送至与AP连接的控制器，控制器可以依据终端的多个RTT中的最小 值，确定RTT基准值。
参见图3，图3是本发明实施例中AP的路旁部署示意图。与AP1连接的终端从位置A移动到位置A1，与AP1连接的终端再从位置A1移动到位置A2。
在上述与AP1连接的终端的移动过程中，RTT的值由大逐渐减小到最小值后，再由最小值逐渐增加。也就是说，与AP1连接的终端在位置A的RTT大于该终端在位置A1的RTT，该终端在位置A1的RTT小于该终端在位置A2的RTT。当与AP1连接的终端在与AP1距离最近的位置A1时，该终端与AP1的RTT最小。
将最接近RTT最小值的RTT称为RTT基准值。RTT基准值是终端和AP之间的物理距离最近时测量得到的RTT，可以代表物理器件芯片的处理时间。为了确定RTT基准值，控制器可以在终端的多个RTT中挑选其中的最小值，将该最小值作为RTT基准值。从而确保RTT基准值的准确性。
此外，控制器还可以依据终端的多个RTT计算多个RTT均值，在多个RTT均值中确定最小值，将该最小值作为RTT基准值。计算RTT均值的目的在于减少异常RTT对确定RTT基准值的影响。
控制器还可以依据终端的多个RTT计算指定周期内的RTT均值。指定周期可以依据实际需求预先设置。作为一个示例，指定周期是1小时，控制器可以依据终端的多个RTT计算1小时内的RTT均值，那么每个小时均有对应的RTT均值，在每个小时均有对应的RTT均值中选择最小值，然后将该最小值作为RTT基准值。
考虑到终端在与每个AP连接时均存在RTT最小值。理论上，在AP型号均一致，对于一个终端而言，在与每个AP连接时RTT最小值是相等的。
在实际的应用过程中，考虑到各方面的因素，如：天气状况、AP的移动速度或设备损耗。即使AP型号均一致，对于一个终端而言，在与每个AP连接过程中RTT最小值也可能不相等。
下面以获取终端RTT基准值为例进行说明，参见图4是本发明实施例中获取RTT基准值的信令交互示意图。
首先，终端与AP连接，AP向控制器上报事件。
然后，AP定时发送RTT探测报文至终端，AP每次获得RTT后，将RTT上报至控制器。
最后，控制器从多个RTT中选择RTT的最小值，将该最小值确定为RTT基准值。
方案一：
控制器可以依据终端与多个AP连接时的多个RTT中的最小值，确定RTT基准值。
具体来说，在终端与一个AP的连接时会有多个RTT。终端与多个AP依次连接和去连接，那么对于每个AP均有多个RTT，多个AP测量到与终端间的多个RTT，基于上述多个RTT确定RTT基准值，可以提高RTT基准值的准确性。
方案二：
与终端连接的AP的型号有可能相同，也有可能不同。对于型号不同的AP，其RTT也是不同的。那么，可以针对每个AP确定该AP对应的RTT基准值。
控制器可以依据与每个AP连接时的RTT中的最小值，确定RTT基准值。具体来说，终端与每个AP连接时，有多个RTT，将多个RTT中的最小值确定为RTT基准值。 也就是说，RTT基准值是依据AP的不同而不同。
针对不同型号的AP，可以确定AP对应的RTT基准值，可以提高RTT基准值的针对性和准确性。
方案三：
考虑到切换AP成功率，切换AP成功率小于预设切换成功率时，则说明AP连接时的RTT准确性可能较差，因此在确定RTT基准值时，则需要放弃之前与AP连接时的RTT。终端的多个RTT只包括终端当前连接的AP测量到与终端间的多个RTT。
例如：AP1、AP2、……、AP10、AP11、AP12顺序排列在高速公路路边，终端从AP1顺序行驶至AP12，终端依次连接AP1、AP2、……、AP12。
终端在AP1至AP10的9次切换过程中，切换AP成功率小于预设切换成功率。在AP10切换至AP11的连接过程中，控制器放弃与终端连接的AP1至AP10连接时的多个RTT。
控制器可以依据与AP10连接时的多个RTT中的最小值，确定RTT基准值，以提高RTT基准值的准确性。
上述三个方案可以依据实际情况选择使用。也就是说，可以同时执行上述三个方案中的多个方案。
S202、如果基于实时RTT和RTT基准值的差值的切换条件被满足，控制器用于指示终端当前连接的AP向终端发送信道切换宣告，信道切换宣告指示终端将工作信道切换为下一个AP的工作信道。
参见图5，AP采集到的RTT时间要比真实的RTT时间多2(T1+T2)的基带芯片处理时间。将2(T1+T2)称为RTT基准值(英文：RTT base value，RTT-BASE)。T1与AP使用的芯片有关，T2与终端使用的芯片有关，因为是往返时延所以是2倍(T1+T2)。所以给定的一对AP和终端的RTT-BASE值是固定的。
L＝(RTT-b)*C/2              (2)
其中b为终端RTT-BASE值，L为终端当前连接的AP与终端的实时距离。
考虑到实时距离的变化与真实RTT相关。
真实RTT＝RTT-b               (3)
真实RTT是终端当前连接的AP与终端实际的往返时延。
实时RTT和RTT基准值的差即真实RTT，真实RTT满足切换条件，控制器则指示终端当前连接的AP向终端发送信道切换宣告，信道切换宣告指示终端将工作信道切换为下一个AP的工作信道。
情况一：
参见图6，图6是以实时距离为依据的切换示意图。终端逐渐接近AP1，由终端的实时距离可以获知终端是否进入切换区域。切换区域是由预先设置的最小切换阈值和预先设置的最大切换阈值确定。
在位置A，终端未进入切换区域。在位置B，终端进入切换区域。控制器判断满足切换条件，控制器则指示终端当前连接的AP向终端发送信道切换宣告。
基于真实RTT和公式(2)可以计算获得当前连接的AP与终端的实时距离。切换条件是大于预先设置的最小切换阈值。
当前连接的AP与终端的实时距离大于预先设置的最小切换阈值，控制器则指示终端当前连接的AP向终端发送信道切换宣告。
情况二：
切换条件是大于预先设置的RTT阈值。图6中切换区域可以是由预先设置的最小RTT阈值和预先设置的最大RTT阈值确定的。
依据公式(3)计算获得的真实RTT，该真实RTT大于预先设置的最小RTT阈值，控制器则指示终端当前连接的AP向终端发送信道切换宣告。
情况三：
切换条件还可以考虑接收的信号强度指示即(英文：Received Signal Strength Indication，RSSI)，以及预先设置的最大切换阈值和预先设置的最小切换阈值。
基于真实RTT和公式(2)可以计算获得当前连接的AP与终端的实时距离，当前连接的AP与终端的实时距离大于预先设置的最小切换阈值且小于预先设置的最大切换阈值，同时满足RSSI小于RSSI阈值，则控制器则指示终端当前连接的AP向终端发送信道切换宣告。
情况四：
切换条件考虑RSSI，以及预先设置的最大RTT阈值和预先设置的最小RTT阈值。
依据公式(3)计算获得的真实RTT，该真实RTT大于预先设置的最大RTT阈值且小于预先设置的最小RTT阈值，同时满足RSSI小于RSSI阈值，控制器则指示终端当前连接的AP向终端发送信道切换宣告。
也就是说，基于实时RTT和RTT基准值的差值满足切换条件，则控制器则指示终端当前连接的AP向终端发送信道切换宣告。
在本发明实施例中，控制器依据终端的多个RTT中的最小值，确定RTT基准值，可以确保RTT基准值的误差较小。如果基于实时RTT和RTT基准值的差值的切换条件被满足，控制器用于指示终端当前连接的AP向终端发送信道切换宣告，信道切换宣告指示终端将工作信道切换为下一个AP的工作信道，从而保障终端通过AP进行通信。
参见图7，图7是本发明实施例中获取终端RTT基准值的信令交互示意图，具体包括：
首先，AP1向终端发送RTT探测报文，终端向AP1回复ACK报文。AP1向控制器上报终端RTT基准值。控制器依据上报的终端RTT基准值确定实时RTT和RTT基准值的差值。
然后，满足切换条件，控制器通过AP1向终端发送信道切换宣告。终端由AP1的工作信道切换至AP2的工作信道，AP2向控制器发送切换结果反馈。
最后，控制器记录切换结果。
参见图8，图8是本发明实施例中控制器的结构示意图，具体包括：计算模块801和发送模块802。每个模块的功能具体参见上述步骤。
参见图9，图9是本发明实施例中网络设备的结构示意图，包括处理器901、端口902，用于实现切换接入点的方法。可选的，网络设备还包括存储器903。
其中，处理器901、端口902、存储器903互相连接，例如用总线互相连接。处理器901可以是中央处理器(CPU)。端口902可以是无线端口或有线端口。其中，无线 端口可以是蜂窝移动网络端口，WLAN端口等。有线端口可以是以太网端口，例如或光端口或电端口。
其中，存储器903可以是只读存储器(ROM)或随机存取存储器(RAM)，磁存储器等。
处理器901依据终端的多个RTT中的最小值，确定RTT基准值；如果基于实时RTT和RTT基准值的差值的切换条件被满足，用端口902指示终端当前连接的AP向终端发送信道切换宣告，信道切换宣告指示终端将工作信道切换为下一个AP的工作信道。
处理器901的具体处理细节参见图2至图8对应的实施例。
在上述实施例中，可以全部或部分地通过软件、硬件、固件或者其任意组合来实现。当使用全部或部分地以计算机程序产品的形式实现，所述计算机程序产品包括一个或多个计算机指令。在计算机上加载或执行所述计算机程序指令时，全部或部分地产生按照本发明实施例所述的流程或功能。所述计算机可以是通用计算机、专用计算机、计算机网络、或者其他可编程装置。所述计算机指令可以存储在计算机可读存储介质中，或者从一个计算机可读存储介质向另一个计算机可读存储介质传输，例如，所述计算机指令可以从一个网站站点、计算机、服务器或数据中心通过有线(例如同轴电缆、双绞线、光纤)或无线(例如红外、无线、微波等)方式向另一个网站站点、计算机、服务器或数据中心进行传输。所述计算机可读取存储介质可以是计算机能够存取的任何介质或者是包含一个或多个介质集成的服务器、数据中心等数据存储设备。所述介质可以是磁性介质(例如，软盘、硬盘、磁带)、光介质(例如，光盘)或者半导体介质(例如固态硬盘(SSD))等。

Claims (13)

  1. 一种切换接入点的方法，其特征在于，所述方法包括：
    控制器依据终端的多个往返时延(RTT)中的最小值，确定RTT基准值；
    如果基于实时RTT和所述RTT基准值的差值的切换条件被满足，所述控制器指示所述终端当前连接的接入点(AP)向所述终端发送信道切换宣告，所述信道切换宣告指示所述终端将工作信道切换为下一个AP的工作信道。
  2. 根据权利要求1所述切换接入点的方法，其特征在于，所述控制器依据终端的多个RTT中的最小值，确定RTT基准值，包括：
    所述控制器依据所述终端的所述多个RTT计算多个RTT均值，将所述多个RTT均值中的最小值确定为所述RTT基准值。
  3. 根据权利要求1或2所述切换接入点的方法，其特征在于，所述终端的多个RTT包括多个AP测量到的与所述终端间的多个RTT。
  4. 根据权利要求1或2所述切换接入点的方法，其特征在于，
    在切换AP成功率小于预设切换成功率时，所述终端的多个RTT只包括所述终端当前连接的AP测量到的与所述终端间的多个RTT。
  5. 一种控制器，其特征在于，所述控制器包括：
    计算模块，用于依据终端的多个往返时延(RTT)中的最小值，确定RTT基准值；
    发送模块，如果基于实时RTT和所述RTT基准值的差值的切换条件被满足，用于指示所述终端当前连接的接入点(AP)向所述终端发送信道切换宣告，所述信道切换宣告指示所述终端将工作信道切换为下一个AP的工作信道。
  6. 根据权利要求5所述控制器，其特征在于，所述计算模块，具体用于依据所述终端的所述多个RTT计算多个RTT均值，将所述多个RTT均值中的最小值确定为所述基准值。
  7. 根据权利要求5或6所述控制器，其特征在于，所述终端的多个RTT包括多个AP测量到的与所述终端间的多个RTT。
  8. 根据权利要求5或6所述控制器，其特征在于，在切换AP成功率小于预设切换成功率时，所述终端的多个RTT只包括所述终端当前连接的AP测量到的与所述终端间的多个RTT。
  9. 一种网络设备，其特征在于，所述网络设备包括处理器和端口，所述处理器用于：
    依据终端的多个往返时延(RTT)中的最小值，确定RTT基准值；
    如果基于实时RTT和所述RTT基准值的差值的切换条件被满足，用所述端口指示所述终端当前连接的接入点(AP)向所述终端发送信道切换宣告，所述信道切换宣告指示所述终端将工作信道切换为下一个AP的工作信道。
  10. 根据权利要求9所述网络设备，其特征在于，所述处理器，具体用于依据所述终端的所述多个RTT计算多个RTT均值，将所述多个RTT均值中的最小值确定为所述基准值。
  11. 根据权利要求9或10所述网络设备，其特征在于，所述终端的多个RTT包括多个AP测量到的与所述终端间的多个RTT。
  12. 根据权利要求9或10所述网络设备，其特征在于，在切换AP成功率小于预设切换成功率时，所述终端的多个RTT只包括所述终端当前连接的AP测量到的与所述终端间的多个RTT。
  13. 一种计算机可读存储介质，包括指令，当其在计算机上运行时，使得计算机执行如权利要求1-4任意一项所述的方法。
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CN113597784B (zh) * 2019-09-17 2023-10-13 Oppo广东移动通信有限公司 用于切换网络设备的方法、终端设备和网络设备
CN110868747B (zh) * 2019-11-28 2020-09-25 上海商米科技集团股份有限公司 一种可应用于多网络模式检测延时并自动切换的方法
CN113632430A (zh) * 2020-03-09 2021-11-09 北京小米移动软件有限公司 信道切换方法、装置、设备及可读存储介质
CN113300898A (zh) * 2020-04-10 2021-08-24 阿里巴巴集团控股有限公司 信息处理方法、系统及电子设备
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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101977423A (zh) * 2010-10-19 2011-02-16 北京航空航天大学 一种车载WiFi设备选择访问点的方法
CN102917424A (zh) * 2012-10-25 2013-02-06 陕西科技大学 一种WiFi通信中AP切换的方法
CN104067670A (zh) * 2012-10-19 2014-09-24 优倍快网络公司 无线网络的分布式无缝漫游

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20120057481A1 (en) * 2010-09-07 2012-03-08 Electronics And Telecommunications Research Institute System and method for measuring round trip time based on wireless local area network
CN102457510B (zh) * 2010-11-02 2016-02-10 中兴通讯股份有限公司 一种hap切换的方法和系统
US8933776B2 (en) * 2012-07-20 2015-01-13 Qualcomm Incorporated Relative positioning applications in wireless devices
US9445227B2 (en) * 2013-08-30 2016-09-13 Qualcomm Incorporated Passive positioning utilizing round trip time information
US20150131460A1 (en) * 2013-11-13 2015-05-14 Qualcomm Incorporated Method and apparatus for using rssi and rtt information for choosing access points to associate with

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101977423A (zh) * 2010-10-19 2011-02-16 北京航空航天大学 一种车载WiFi设备选择访问点的方法
CN104067670A (zh) * 2012-10-19 2014-09-24 优倍快网络公司 无线网络的分布式无缝漫游
CN102917424A (zh) * 2012-10-25 2013-02-06 陕西科技大学 一种WiFi通信中AP切换的方法

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