JP4536673B2 - Radio base station and radio channel update method - Google Patents

Description

  The present invention relates to a radio base station and a radio channel update method having a function of determining a radio channel for performing radio communication and dynamically updating a radio channel in a radio frame communication system such as a wireless LAN.

  As a representative wireless frame communication system related to the present invention, for example, there is a wireless LAN system compliant with the standard IEEE802.11 by the American standardization organization IEEE (Non-patent Document 1). In the present specification, this standard is referred to as IEEE 802.11 standard.

  As shown in FIG. 7, the wireless LAN system transmits and receives a wireless frame using a wireless channel having a frequency with a wireless base station 71 and slave stations 73 and 74 existing in the communication area 72. The radio channel used by the radio base station is selected by a user who operates the normal radio base station, or automatically set by the radio base station. In addition, there are operation methods such as using a fixed radio channel for the first time or using a DFS (Dynamic Frequency Selection) function (Non-Patent Document 2) for dynamically updating the radio channel.

When a general radio base station that implements the DFS function determines a radio channel to be operated from various conditions at the time of startup, and thereafter checks the radio wave condition of each radio channel periodically and meets the conditions to be changed ( For example, when avoiding interference), a good radio channel is selected again and changed. In this case, the shorter the DFS cycle, the quicker the response to changes in radio wave conditions. However, since communication cannot be performed while the radio channel is being inspected, if the DFS cycle is short, the time that can be used for actual communication is shortened and communication efficiency is reduced. On the other hand, if the DFS period is long, the time required for checking the radio channel is shortened and communication efficiency is increased, but the response to the change in the radio wave state is delayed. For this reason, it is common to set a relatively long time such as 10 minutes for this DFS cycle.
IEEE 802.11, "Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications", IEEE std 802.11, 1999 IEEE 802.11h, "Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications, Amendment 5: Spectrum and Transmit Power Management Extensions in the 5 GHz band in Europe", IEEE 802.11 Std., Sep. 2003

  In the radio base station in which the DFS function is valid, the radio wave state of the radio channel is periodically checked to determine whether the radio channel needs to be changed. That is, the radio base station is set in a reception state for each selectable radio channel for a predetermined time, and checks whether there is another radio base station using the same radio channel. When another radio base station using the same radio channel is detected, the radio channel used by either radio base station is changed. However, if the other radio base station is operated with a fixed channel, the other radio base station will not change the radio channel, so the radio channel used by this radio base station will be changed. Become. In the normal DFS, even if another radio base station using the same radio channel appears, the appearance cannot be detected until the next DFS cycle, and the radio base station does not change the radio channel. During this time, the communication speed of the communication of the radio base station is degraded due to the overlap of the radio channels.

  As described above, in the conventional DFS, when another radio base station using the same radio channel appears, the update cycle is a relatively long time, and thus it may not be possible to immediately respond to a change in the situation. In particular, if the other radio base station appears on the same radio channel in a setting that uses a fixed radio channel instead of DFS, the radio channel used by this radio base station must be changed. Must wait for the DFS period. At this time, there is a possibility that a failure occurs in communication between the radio base station and the slave station due to the use of competing radio channels, which becomes a problem when the DFS cycle is long.

  The present invention is a wireless base station that dynamically updates a wireless channel to be used, and when another wireless base station using the same wireless channel appears, the wireless channel updating process is immediately performed without waiting for the DFS period. It is an object of the present invention to provide a radio base station and a radio channel update method that can start the communication.

  1st invention uses the same radio channel in a mutual communication area in the radio base station which communicates with several sub-stations by the operation method which changes the radio channel to be used dynamically according to the surrounding situation When there is a plurality of radio base stations and each radio base station adopts an operation method of fixing a radio channel to be used or dynamically changing a radio channel to be used, our radio base station A frame transmission unit that transmits a radio frame that stores information indicating an operation method of a radio channel used by the mobile station, and a frame reception unit that receives a radio frame that stores information indicating an operation method transmitted from a destination radio base station; The wireless channel is dynamically changed when it is detected from the radio frame received by the frame receiver that the other radio base station is an operation method for fixing the radio channel. And a determination unit to start the process.

  According to a second aspect of the present invention, in a radio base station that communicates with a plurality of slave stations by an operation method that dynamically changes a radio channel to be used according to surrounding conditions, the same radio channel is used in each other's communication area. When there is a plurality of radio base stations and the operation method of dynamically changing the radio channel used by each radio base station is taken, a radio frame storing information indicating the update period of the radio channel in our radio base station is stored. A frame transmission unit for transmission, a frame reception unit for receiving a radio frame storing information indicating an update period transmitted from a destination radio base station, and a destination radio base station detected from the radio frame received by the frame reception unit A determination unit that starts a process of dynamically changing the wireless channel when the update period of the wireless channel is equal to or greater than a predetermined value.

  According to a third aspect of the present invention, in a radio base station that communicates with a plurality of slave stations by an operation method that dynamically changes a radio channel to be used according to surrounding conditions, the same radio channel is used in each other's communication area. When there is a plurality of radio base stations and the operation method of dynamically changing the radio channel used by each radio base station is taken, a radio frame storing information indicating the update period of the radio channel in our radio base station is stored. A frame transmission unit for transmission, a frame reception unit for receiving a radio frame storing information indicating an update period transmitted from a destination radio base station, and a destination radio base station detected from the radio frame received by the frame reception unit And a determination unit that starts a process of dynamically changing the radio channel when the update cycle of the radio channel is equal to or greater than our update cycle.

  According to a fourth aspect of the present invention, in the radio channel update method of a radio base station that communicates with a plurality of slave stations by an operation method that dynamically changes the radio channel to be used according to surrounding conditions, When there are a plurality of radio base stations that use radio channels and the radio channel used by each radio base station is fixed or the radio channel to be used is dynamically changed, the operation method is either Received and received a radio frame storing information indicating the operation method of the radio channel used by our radio base station and receiving information indicating the operation method transmitted from the other radio base station When it is detected from the radio frame that the other radio base station operates the radio channel in a fixed manner, processing for dynamically changing the radio channel is started.

  According to a fifth aspect of the present invention, in the radio channel update method of a radio base station that communicates with a plurality of slave stations by an operation method that dynamically changes a radio channel to be used according to surrounding conditions, the same is applied to each other in a communication area. When there is a plurality of radio base stations that use radio channels and the operation method of dynamically changing the radio channel used by each radio base station is taken, information indicating the update period of the radio channel in this radio base station is displayed. The stored radio frame is transmitted, the radio frame storing the information indicating the update cycle transmitted from the other radio base station is received, and the radio channel update cycle of the other radio base station detected from the received radio frame is received. When it is equal to or greater than the predetermined value, a process of dynamically changing the radio channel is started.

  According to a sixth aspect of the present invention, in the radio channel update method of a radio base station that communicates with a plurality of slave stations by an operation method that dynamically changes a radio channel to be used according to surrounding conditions, the same is used in each communication area. When there is a plurality of radio base stations that use radio channels and the operation method of dynamically changing the radio channel used by each radio base station is taken, information indicating the update period of the radio channel in this radio base station is displayed. The stored radio frame is transmitted, the radio frame storing the information indicating the update cycle transmitted from the other radio base station is received, and the radio channel update cycle of the other radio base station detected from the received radio frame is received. If it is longer than our update cycle, the process of dynamically changing the radio channel is started.

  In the wireless base station that dynamically changes the wireless channel to be used, when a wireless base station using the same wireless channel appears and the wireless base station is operating the wireless channel fixedly, Or if the radio channel is dynamically changed but its update period is greater than or equal to the specified value or longer than the update period of our radio base station, our radio base station immediately starts the update process of the radio channel can do. As a result, it is possible to respond quickly to changes in the radio wave condition of the radio channel without waiting for the update process of the radio channel in the other radio base station and irrespective of the update period of the radio base station.

  FIG. 1 shows a configuration example of a main part of a radio base station of the present invention. In the figure, main parts of the radio base station 10 according to the present invention are a frame transmission unit 11 and a frame reception unit 12 that transmit and receive a radio frame via an antenna 15, a determination unit 13 connected to the frame reception unit 12, and a DFS. It is comprised from the channel setting part 14 which selects a radio channel.

  FIG. 2 shows an example of exchange of Probe Request / Probe Response frames between radio base stations. In the figure, the wireless base stations 10-1 and 10-2 existing in the communication areas 72-1 and 72-2 are IEEE802.11 standard management frames at the time of activation and periodically used wireless channels. Send and receive Probe Request / Probe Response frames. Here, an example of transmission / reception in only one direction is shown.

  In the frame transmission unit 11 of the radio base station of the present invention, a field (Request Information) 31 that is uniquely defined is added to the Probe Request frame to be transmitted as shown in FIG. In this unique field 31, information for notifying whether the radio channel operation method is fixed or dynamically updated using DFS is described. The radio base station that has received the Probe Request frame by the frame receiver 12 returns a Probe Response frame in accordance with the specifications of the IEEE802.11 standard. Upon receiving the probe request frame reception notification from the frame receiving unit 12, the frame transmitting unit 11 adds a field (Requested Information) 32 that is uniquely defined to the probe response frame to be transmitted as shown in FIG. In this unique field 32, similarly to the unique field 31, information for notifying the radio channel operation method is described. In addition, when the radio base station dynamically updates the radio channel using DFS, information on the DFS period may be added to the unique fields 31 and 32. Hereinafter, processing procedure examples 1 to 3 in the radio base station of the present invention will be described with reference to FIGS.

(Processing procedure example 1 of a radio base station)
1 to 3 and 4, the radio base station 10 that dynamically updates the radio channel using DFS automatically selects a radio channel and starts operation (S11). The frame receiving unit 12 transmits / receives a frame using the selected wireless channel. Here, when the frame receiving unit 12 of the radio base station 10 receives a Probe Request frame or a Probe Response frame (S12), the determining unit 13 refers to the unique field 31 or 32 therein (S13). As a result of referring to the information in the unique field 31 or 32, when it is detected that the radio channel used by this radio base station is operating as a fixed channel, the determination unit 13 In response to this instruction, the channel setting unit 14 immediately starts DFS processing (radio channel update processing) (S14), and selects a radio channel other than the radio channel used (S15). Next, the radio channel is changed to the selected radio channel (S16) and used in the subsequent operation.

  That is, in this processing procedure example 1, between the radio base station A that dynamically updates the radio channel using DFS and the radio base station B of the fixed channel, the radio base station A is the other radio base station. By detecting that B is a fixed channel by exchanging Probe Request / Probe Response frames, the wireless channel update process can be started immediately without waiting for the DFS period.

(Radio base station processing procedure example 2)
Here, both radio base stations that transmit and receive the Probe Request / Probe Response frame dynamically update the radio channel using DFS, and each of the unique fields 31 and 32 of the Probe Request / Probe Response frame has its own field. It is assumed that information on the DFS period is added.

  In the processing procedure example 2 shown in FIG. 5, there is a difference in the processing S13 of the determination unit 13 in the processing procedure example 1 shown in FIG. 4, and the others are the same. In S13a instead of S13, the determination unit 13 of the radio base station 10 refers to the information in the unique field 31 or 32 in the Probe Request frame or Probe Response frame. As a result, the same radio channel as that of our radio base station is used. If the other radio base station is set to dynamically update the radio channel and the DFS cycle is detected to be greater than or equal to a predetermined value, the channel setting unit 14 immediately receives an instruction from the determination unit 13 DFS processing (radio channel update processing) is started.

  That is, in this processing procedure example 2, in the radio base stations A and B that dynamically update the radio channel using DFS, the DFS cycle of the radio base station A is equal to or greater than a predetermined value, and the DFS cycle of the radio base station B is When it is less than the predetermined value, the radio base station B immediately detects that the DFS period of the radio base station A is equal to or greater than the predetermined value by exchanging Probe Request / Probe Response frames, and immediately waits without waiting for the DFS period. The radio channel update process can be started. Note that, when the DFS period of both the radio base stations A and B is equal to or greater than the predetermined value, the radio channel update process is immediately started. However, when both of the DFS periods are less than the predetermined value, the respective DFS periods are set. Based on this, the radio channel update process is started.

(Processing procedure example 3 of a radio base station)
Here, both radio base stations that transmit and receive the Probe Request / Probe Response frame dynamically update the radio channel using DFS, and each of the unique fields 31 and 32 of the Probe Request / Probe Response frame has its own field. It is assumed that information on the DFS period is added.

  In the processing procedure example 3 shown in FIG. 6, there is a difference in the processing S13 of the determination unit 13 of the processing procedure example 1 shown in FIG. In S13b instead of S13, the determination unit 13 of the radio base station 10 uses the same radio channel as that of our radio base station as a result of referring to the information in the unique field 31 or 32 in the Probe Request frame or Probe Response frame. When it is detected that the other radio base station dynamically updates the radio channel and that the DFS cycle is equal to or greater than the DFS cycle of the radio base station, the channel according to the instruction of the determination unit 13 The setting unit 14 immediately starts DFS processing (radio channel update processing).

  That is, in this processing procedure example 3, in the radio base stations A and B that dynamically update the radio channel using DFS, the DFS cycle of the radio base station A is longer than the DFS cycle of the radio base station B. By detecting this by exchanging Probe Request / Probe Response frames, the radio base station B can immediately start the radio channel update process without waiting for the DFS cycle. When the DFS cycle of the radio base station A is shorter than the DFS cycle of the radio base station B, the radio base station A immediately starts the radio channel update process without waiting for the DFS cycle.

The figure which shows the structural example of the principal part of the wireless base station of this invention. The figure which shows the exchange example of Probe Request / Probe Response frame between wireless base stations. The figure which shows the format of a Probe Request / Probe Response frame. The flowchart which shows the process procedure example 1 of the wireless base station of this invention. The flowchart which shows the process procedure example 2 of the wireless base station of this invention. The flowchart which shows the process sequence example 3 of the wireless base station of this invention. The figure which shows the structural example of a wireless LAN system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Radio base station 11 Frame transmission part 12 Frame reception part 13 Judgment part 14 Channel setting part 31, 32 Original field 71 Wireless base station 72 Communication area 73, 74 Child station

Claims (6)

In a radio base station that communicates with multiple slave stations with an operation method that dynamically changes the radio channel to be used according to the surrounding situation,
There are multiple radio base stations that use the same radio channel in each other's communication area, and each radio base station either fixes the radio channel to be used or dynamically changes the radio channel to be used When taking the operation method,
A frame transmission unit for transmitting a radio frame storing information indicating the operation method of the radio channel used by our radio base station;
A frame receiving unit that receives a radio frame storing information indicating the operation method transmitted from a destination radio base station;
A determination unit that starts a process of dynamically changing a radio channel when it is detected from the radio frame received by the frame reception unit that the destination radio base station is an operation method of fixing a radio channel; A radio base station comprising: In a radio base station that communicates with multiple slave stations with an operation method that dynamically changes the radio channel to be used according to the surrounding situation,
When there is a plurality of radio base stations using the same radio channel in each other's communication area, and taking an operation method of dynamically changing the radio channel used by each radio base station,
A frame transmitter for transmitting a radio frame storing information indicating an update period of a radio channel in our radio base station;
A frame receiving unit for receiving a radio frame storing information indicating the update period transmitted from a destination radio base station;
A determination unit that starts a process of dynamically changing a radio channel when an update period of a radio channel of the destination radio base station detected from the radio frame received by the frame reception unit is equal to or greater than a predetermined value; A radio base station characterized by comprising. In a radio base station that communicates with multiple slave stations with an operation method that dynamically changes the radio channel to be used according to the surrounding situation,
When there is a plurality of radio base stations using the same radio channel in each other's communication area, and taking an operation method of dynamically changing the radio channel used by each radio base station,
A frame transmitter for transmitting a radio frame storing information indicating an update period of a radio channel in our radio base station;
A frame receiving unit for receiving a radio frame storing information indicating the update period transmitted from a destination radio base station;
A determination unit for starting a process of dynamically changing a radio channel when an update period of a radio channel of the destination radio base station detected from the radio frame received by the frame reception unit is equal to or greater than our update period And a radio base station. In a radio channel update method of a radio base station that communicates with a plurality of slave stations by an operation method that dynamically changes a radio channel to be used according to surrounding conditions,
There are multiple radio base stations that use the same radio channel in each other's communication area, and either the radio channel used by each radio base station is fixed, or the radio channel used is dynamically changed When taking the operation method,
Sending a radio frame storing information indicating the operation method of the radio channel used by our radio base station,
Receiving a radio frame storing information indicating the operation method transmitted from the other radio base station;
A radio channel of a radio base station, wherein a process of dynamically changing a radio channel is started when it is detected from the received radio frame that the destination radio base station operates a radio channel in a fixed manner Update method. In a radio channel update method of a radio base station that communicates with a plurality of slave stations by an operation method that dynamically changes a radio channel to be used according to surrounding conditions,
When there is a plurality of radio base stations using the same radio channel in each other's communication area, and taking an operation method of dynamically changing the radio channel used by each radio base station,
Send a radio frame that stores information indicating the update period of the radio channel in our radio base station,
Receiving a radio frame storing information indicating the update period transmitted from the other radio base station;
A process of dynamically changing a radio channel is started when an update period of a radio channel of the destination radio base station detected from the received radio frame is equal to or greater than a predetermined value. Radio channel update method. In a radio channel update method of a radio base station that communicates with a plurality of slave stations by an operation method that dynamically changes a radio channel to be used according to surrounding conditions,
When there is a plurality of radio base stations using the same radio channel in each other's communication area, and taking an operation method of dynamically changing the radio channel used by each radio base station,
Send a radio frame that stores information indicating the update period of the radio channel in our radio base station,
Receiving a radio frame storing information indicating the update period transmitted from the other radio base station;
A radio base that starts a process of dynamically changing a radio channel when an update period of a radio channel of the destination radio base station detected from the received radio frame is greater than or equal to our update period. Station radio channel update method.

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