Patent Publication Number: US-2023164675-A1

Title: Access point in mesh network for initiating dynamic frequency selection flow and methods of operating the same

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a mesh network, and in particular, to an access point in a mesh network for initiating a dynamic frequency selection flow and methods of operating the same. 
     2. Description of the Prior Art 
     A multiple access point (Multi-AP) network, also known as a mesh network, is a network architecture proposed by WiFi Alliance, being suitable for providing connections between multiple access points/routers in a large space to expand coverage of wireless network signals. 
     The regulation specifies that an access point in a mesh network needs to execute a dynamic frequency selection (DFS) flow when a DFS channel is adopted in the mesh network. The DFS channel is a channel for transmitting radar signals. In the DFS flow, if the access point in the wireless network uses the DFS channel as the operation channel, upon the access point detecting a radar signal, the access point needs to switch its operation channel to another channel, and is forbidden to return to the original DFS channel in a time interval as specified by the regulation. 
     The mesh network includes multi-AP controllers and multi-AP agents. If only one multi-AP agent detects a radar signal, only the multi-AP agent will execute the DFS flow for switching channels. The multi-AP controller will continue to run on the original DFS channel, resulting in a disconnection of a link between the multi-AP controller and the multi-AP agent, stopping the multi-AP agent from providing WiFi services, leading to poor user experience around the multi-AP agent. 
     SUMMARY OF THE INVENTION 
     According to an embodiment of the invention, a first access point in a mesh network includes a transceiver and a processor. The processor is coupled to the transceiver, and is used to determine whether a second access point transmitting a beacon belongs to the mesh network upon detecting the beacon; if the second access point belongs to the mesh network, determine whether the beacon includes first channel switch announcement information; and if the beacon includes the first channel switch announcement information, configure the transceiver to transmit second channel switch announcement information, and switch the first access point to a target channel. The first channel switch announcement information and the second channel switch announcement information comprise information of the target channel. 
     According to another embodiment of the invention, a method of operating a first access point in a mesh network includes after detecting a beacon, a processor of the first access point determining whether a second access point transmitting the beacon belongs to the mesh network, if the second access point belongs to the mesh network, the processor determining whether the beacon includes first channel switch announcement information, and if the beacon includes the first channel switch announcement information, a transceiver of the first access point transmitting second channel switch announcement information, and switching the first access point to a target channel. The first channel switch announcement information and the second channel switch announcement information comprise information of the target channel. 
     According to another embodiment of the invention, a method of operating an access point in a mesh network includes receiving a 1905 packet, and if the 1905 packet includes information of a target channel, a transceiver of the access point transmitting channel switch announcement information comprising the information of the target channel, and switching the access point to the target channel. 
     These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic diagram of a mesh network according to an embodiment of the invention. 
         FIG.  2    is a block diagram of an access point according to an embodiment of the invention. 
         FIG.  3    is a flowchart of an operation method of operating the access point in  FIG.  1    according to an embodiment of the invention. 
         FIG.  4    is a flowchart of an operation method of operating the access point in  FIG.  1    according to another embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIG.  1    is a schematic diagram of a mesh network  1  according to an embodiment of the invention. The mesh network  1  may be a wireless mesh network including a multi-access point (multi-AP) controller and one or more multi-AP agents. The mesh network  1  may adopt multi-AP specification version 2.0, IEEE 1905.1 protocol, and IEEE 802.11 protocol, where IEEE 802.11 specifies the communication protocols of the physical layer and the data link layer, and IEEE 1905.1 specifies the communication protocol of the convergence layer above the data link layer. The access points in the mesh network  1  may communicate with each other using 1905 packets. In  FIG.  1   , the mesh network  1  includes access points  10  to  14 . The access point  10  may be configured as a multi-AP controller, and the access points  12  and  14  may be configured as multi-AP agents. The multi-AP controller may control the mesh network  1 . For example, the access point  10  may determine connection statuses of the access points  10  to  14 , select an operation channel for the mesh network  1 , and control channel switching. The multi-AP agents may execute instructions from the multi-AP controller. For example, the access points  12  and  14  may receive instructions from the access point  10  to obtain a selected channel. If the mesh network  1  employs a dynamic frequency selection (DFS) channel to provide WiFi services, when the access point  12  or  14  detects a radar signal, all the access points  10  to  14  in the mesh network  1  will execute the DFS flow to switch to the same target channel, maintaining connections between the access points  10  to  14  and continuously providing WiFi services. 
     The access points  10  to  14  may be sequentially coupled in a wireless manner. The access points  10  to  14  may be set up at different locations to provide coverages C 10  to C 14 , respectively. For example, the access points  10  to  14  may be set up at the 1st to 3rd floors of a house, and provide WiFi services in the coverages C 10  to C 14 , respectively. The access point  10  may be additionally coupled to a wide area network (WAN)  18 . A wireless station  16  may be coupled to the access point  14  in a wireless manner. The access points  10  to  14  may provide WiFi services via the same channel. When the wireless station  16  moves, the WiFi service may be obtained from the access point  10 ,  12 , or  14  via the same channel, and thus, the access points  10  to  14  may be regarded as a single wireless network with the coverages C 10  to C 14 . 
     The access points  10  to  14  may have a single-frequency, dual-frequency, or multi-frequency transmission capabilities. The operation of the mesh network  1  is explained with the access points  10  to  14  having single-frequency transmission capability in the 5 GHz band. The DFS channels are located in the 5 GHz band. If a DFS channel is selected as the operation channel of the mesh network  1 , the access points  10  to  14  may listen for a radar signal in the operation channel in a first predetermined period such as 1 minute. If no radar signal is detected in the first predetermined period, the access points  10  to  14  may start to use the selected channel to provide WiFi services. For example, channels  56  to  144  in the 5 GHz band may be the DFS channels, the access point  10  may select a DFS channel  56  from the 5 GHz channels, and notify the access points  12  and  14  to use the DFS channel  56  to provide WiFi services. The access points  10  to  14  may listen for a radar signal in the DFS channel  56  for 1 minute, and if no radar signal is detected, start to use DFS channel  56  to provide WiFi services. Later, if one of the access points  10  to  14  detects that a radar signal is in the DFS channel, the access point that detects the radar signal may switch the channel. If the access point of detecting the radar signal is the access point  10 , the access point  10  may transmit channel switch announcement (CSA) information to initiate a DFS flow, and the mesh network  1  will switch from the current DFS channel to another channel in a second predetermined period, e.g., in 500 microseconds, and the original DFS channel is forbidden for use in a third predetermined period, e.g., in 30 minutes. The CSA information may be transmitted via a beacon. If the access point  12  or  14  detects the radar signal, the access point  12  or  14  may issue a beacon including the CSA information and/or a 1905 packet including information of a target channel. so as to notify the access point  10  to initiate the DFS flow, as detailed in the operation method  300  in  FIG.  3   . Correspondingly, the access point  10  may initiate the DFS flow as detailed in the operation method  400  in  FIG.  4    upon confirming that the beacon including the CSA information and/or the 1905 packet including the information of the target channel is transmitted from the access point  12  or  14  in the mesh network  1 . The operation methods  300  and  400  will be described in detail in subsequent paragraphs. 
     The access point  10  may use a media access control (MAC) address or other network identification information to determine whether the beacon and/or 1905 packet is originated from the access point  12  or  14  belonging to the mesh network  1 . For example, the access point  15  may be located near the access point  10  and does not belong to the mesh network  1 . The access point  15  will not communicate with the access points  10  to  14  in the mesh network  1  using the 1905 packets, but the access points  10  to  14  may receive beacons from the access point  15 . Upon establishing the mesh network  1 , the access point  10  may store MAC addresses of the access points  12  and  14 . Since a beacons transmitted by one of the access points  12  to  15  will contain the MAC address thereof, the access point  10  may compare the MAC address in the beacon to the MAC addresses stored in the access point  10  to determine whether the beacon is transmitted by an access point in the mesh network  1 . When the MAC address in the beacon matches a MAC address stored in the access point  10 , the access point  10  may determine that the beacon is transmitted from the access point  12  or  14  in the mesh network  1 . When the MAC address in the beacon does not match a MAC address stored in the access point  10 , the access point  10  may determine that the beacon is transmitted from the access point  15  outside the mesh network  1 . 
     In some embodiments, the access point  10  does not need to store the MAC addresses of the access points  12  and  14 , instead, a beacon transmitted by the access points  12  and  14  may carry network identification information, and the access point  10  may use the network identification information in the beacon to determine whether the beacon is transmitted from a access point in the mesh network  1 . For example, the network identification information may be equipment vendor information. When equipment vendor information in the beacon matches the equipment vendor information of the access point  10 , the access point  10  may determine that the beacon is transmitted from the access point  12  or  14  in the mesh network  1 . When equipment vendor information in the beacon does not match the equipment vendor information of the access point  10 , the access point  10  may determine that the beacon is transmitted from the access point  15  outside the mesh network  1 . In another example, the network identification information may be a service set identifier (SSID) of the mesh network  1 . When a SSID in the beacon matches the SSID of the access point  10 , the access point  10  may determine that the beacon is transmitted from the access point  12  or  14  in the mesh network  1 . When a SSID in the beacon does not match the SSID of the access point  10 , the access point  10  may determine that the beacon is transmitted from the access point  15  outside the mesh network  1 . In some embodiments, the 1905 packet may include a vendor specific message, which may include the information of the target channel, a MAC address of the access point transmitting the 1905 packet, or other DFS information. The access point  10  may determine that the 1905 packet is transmitted from the access point  12  or  14  in the mesh network  1  according to the MAC address or other DFS information in the 1905 packet. 
       FIG.  2    is a block diagram of the access point  10 ,  12 , or  14  in  FIG.  1   , with the access point  10  being used as an example. The access point  10  includes a transceiver  20 , a processor  22 , and a memory  24 . The processor  22  is coupled to the transceiver  20  and the memory  24 . While  FIG.  2    only shows one set of transceiver  20 , those familiar with the art will recognize that for dual-band or multi-band access points  10 ,  12 , or  14 , access points  10 ,  12 , or  14  may include 2 or more sets of transceivers for transmitting and receiving  2  or more WiFi signals simultaneously. 
       FIG.  3    is a flowchart of the operation method  300  for use in the access point  12  or  14 . The operation method  300  includes Steps S 302  to S 308  for use to trigger the DFS flow and transmit a 1905 packet and a first beacon upon detection of a radar signal. Any reasonable step change or adjustment is within the scope of the disclosure. Steps S 302  to S 308  are detailed as follows: 
     Step S 302 : Provide WiFi service on a DFS channel; 
     Step S 304 : Determine whether a radar signal is detected? If so, proceed to Step S 306 ; if not, return to Step S 302 ; 
     Step S 306 : Transmit a 1905 packet including the information of the target channel; 
     Step S 308 : Transmit a first beacon including the CSA information, and switch the channel. 
     In Step S 302 , the access point  12  or  14  provides WiFi services on the DFS channel while continuously monitoring the radar signal. In Step S 304 , if the processor  22  of the access point  12  or  14  determines that a radar signal is detected in the DFS channel, the access point  12  or  14  will notify the access point  10  of the detection (Steps S 306  and S 308 ). If the processor  22  of the access point  12  or  14  determines that no radar signal is detected in the DFS channel, the access point  12  or  14  will continue to provide WiFi services on the DFS channel (Step S 302 ). In Step S 306 , the transceiver  20  of the access point  12  or  14  will transmit a 1905 packet including the information of the target channel. In Step S 308 , the transceiver  20  of the access point  12  or  14  will periodically transmit a first beacon including the CSA information at intervals of a fourth predetermined period, and the access point  12  or  14  will switch to the target channel after the second predetermined period. The target channel is selected by the processor  22 . The CSA information in the first beacon includes the information of the target channel and a switching countdown. For example, the fourth predetermined period may be 100 microseconds, the transceiver  20  of the access point  12  or  14  may transmit the first beacon including the CSA information at intervals of 100 microseconds, and the first beacon transmitted at 500 microseconds after detecting the radar signal includes the information of the target channel and the switching countdown of 0. When the switching countdown reaches 0, the access points  10  to  14  will switch to the target channel. 
     While the operation method  300  adopts the 1905 packet and the first beacon to transmit the information of the target channel, in some embodiments, the operation method  300  may omit Step S 306  and only adopt the first beacon to transmit the information of the target channel, for the access point  10  to trigger the DFS flow in a fast and reliable manner. 
       FIG.  4    is a flowchart of the operation method  400  for use in the access point  10 . The operation method  400  includes Steps S 402  to S 412  for use to trigger the DFS flow upon receiving the 1905 packet or the first beacon. Any reasonable step change or adjustment is within the scope of the disclosure. Steps S 402  to S 412  are detailed as follows: 
     Step S 402 : Provide WiFi service on a DFS channel; 
     Step S 404 : Determine whether a 1905 packet includes the information of a target channel? If so, go to Step S 406 ; and if not, go to Step S 408 ; 
     Step S 406 : Transmit a second beacon including the CSA information, and switch the channel; 
     Step S 408 : Determine whether a first beacon is detected? If so, go to Step S 410 ; and if not, go back to Step S 402 ; 
     Step S 410 : Determine whether the access point transmitting the first beacon belongs to the mesh network  1 ? If so, go to Step S 412 ; and if not, return to Step S 402 ; 
     Step S 412 : Determine whether the first beacon includes the CSA information? If so, go to Step S 406 ; and if not, go back to Step S 402 . 
     In Step S 402 , the access point  10  provides WiFi services on the DFS channel while continuously monitoring the radar signal. In Step S 404 , if the processor  22  of the access point  10  determines that a 1905 packet including the information of a target channel is detected, since only the access points  10  to  14  in the mesh network  1  can communicate using the 1905 packet, the processor  22  of the access point  10  may determine that the 1905 packet is transmitted from the access point  12  or  14 , and the transceiver  20  of the access point  10  will transmit a second beacon including the CSA information, and switch the access point  10  to the target channel after the second predetermined period (Step S 406 ). The CSA information in the second beacon includes the information of the target channel and the switching countdown. When the switching countdown reaches 0, the access point  10  switches to the target channel. 
     If the processor  22  of the access point  10  determines in Step S 404  that no 1905 packet including the information of a target channel is received, the processor  22  of the access point  10  will continue to determine whether the first beacon is detected (Step S 408 ). If no first beacon is detected, the access point  10  does not need to switch the channel, and therefore, the access point  10  returns to Step S 402  to continue to provide WiFi services on the DFS channel. If the first beacon is detected, the processor  22  of the access point  10  determines whether the access point transmitting the first beacon belongs to the mesh network  1  (Step S 410 ). The memory  26  of the access point  10  may store the MAC addresses of the access points  12  and  14  upon establishment of the mesh network  1 . The processor  22  of the access point  10  determines whether the beacon mesh network access point  1  by comparing the MAC address  26  of the first beacon to a MAC address in the first memory. In some embodiments, the access point  10  of the processor  22  may determine whether the beacon mesh network access point  1  by comparing the network identification information in the first beacon and the network identification information of the access point  10 . 
     If the access point transmitting the first beacon belongs to the mesh network  1 , the processor  22  of the access point  10  continues to determine whether the first beacon includes the CSA information (Step S 412 ). If the access point that transmitting the first beacon does not belong to the mesh network  1 , the access point  10  does not need to switch the channel, and returns to Step S 402  to continue to provide WiFi services on the DFS channel. 
     If the first beacon includes the CSA information, the transceiver  20  of the access point  10  transmits a second beacon including the CSA information, and the access point  10  is switched to the target channel after the second predetermined period (Step S 406 ). If the first beacon does not include the CSA information, the access point  10  does not need to switch the channel, and the access point  10  returns to Step S 402  to continue to provide WiFi services on the DFS channel. 
     While the operation method  400  uses 1905 packets and the first beacons to determine whether to initiate the DFS flow, in some embodiments, the operation method  400  may omit Step S 404  and only use the first beacon to determine whether to initiate the DFS flow, for the access point  10  to trigger the DFS flow in a fast and reliable manner. 
     The embodiment in  FIGS.  1  to  4    uses the 1905 packet and beacons of the mesh network  1  to determine whether to initiate the DFS flow. When the access point  12  or  14  detects a radar signal, all the access points  10  to  14  in the mesh network  1  will execute the DFS flow to switch to a common target channel, maintaining the connections between access points  10  to  14  and continuing to provide WiFi services. 
     Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.