JP2012156870A - Radio base station and communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio base station and a communication method in a radio communication system where a communication area which a prescribed radio base station in a communication disabled state covers is prevented from becoming out-of-service without increasing interference of a radio wave between adjacent base stations when the radio base station becomes in the communication disabled state.SOLUTION: A standby level control section 7 reduces a standby zone selection level and/or a standby zone holding level of a self-station in the case of a stop state in which the adjacent base station cannot be communicated. A control channel managing section 6 informs a radio terminal of the reduced standby zone selection level and/or the standby zone holding level.

Description

  The present invention relates to a radio base station and a communication method, and more particularly to a radio base station and a communication method capable of notifying a radio terminal of a standby zone selection level and / or a standby zone holding level.

  Wireless base stations such as the PHS (Personal Handy-phone System) system check the status of the control channel transmitted by the adjacent base station at the time of start-up, and use the control channel at a timing different from the control channel timing of the adjacent base station (See, for example, Patent Document 1 (Japanese Patent Laid-Open No. 9-107323)).

  The wireless terminal receives the standby zone selection level and the standby zone holding level from the wireless base station through the broadcast channel. The wireless terminal sets a wireless base station that transmits a control channel received at a reception level equal to or higher than the standby zone selection level as a standby base station. Further, the setting of the standby base station is maintained unless the reception level of the set control channel of the standby base station falls below the standby zone holding level at a constant rate in a certain period.

JP-A-9-107323

  By the way, when a failure occurs in a certain radio base station and communication becomes impossible in the radio base station, the communication area covered by the radio base station becomes out of range.

  In order to avoid this, it is also possible to increase the transmission output of the radio base station adjacent to the base station where communication is disabled, and recover the area covered by the base station where communication was disabled However, when a plurality of adjacent base stations increase the transmission output, radio wave interference increases between these radio base stations.

  Therefore, an object of the present invention is to provide a wireless base station that is in a communication disabled state without increasing radio wave interference between adjacent base stations when a wireless base station is in a communication disabled state. It is to provide a radio base station and a communication method in a radio communication system that can prevent the communication area covered by the mobile phone from being out of service area.

  In order to solve the above-described problem, the radio base station of the present invention has a standby level that reduces the standby zone selection level and / or standby zone holding level of the local station when the adjacent base station is in a communication stop state. A control unit; and a notification unit that notifies the wireless terminal of the reduced standby zone selection level and / or standby zone retention level.

  According to the present invention, when a certain wireless base station becomes incapable of communication, the wireless base station that has become incapable of communication is covered without increasing radio wave interference between adjacent base stations. It is possible to prevent the communication area from being out of service area.

It is a figure showing the structure of the radio | wireless communications system of embodiment of this invention. It is a figure showing the structure of the wireless base station of 1st Embodiment. (A) is a figure showing the communication area area before it will be in the stop state where a base station cannot communicate. (B) is a figure for demonstrating the communication area area when a certain base station will be in the stop state which cannot communicate. (C) is a figure for demonstrating the communication area area when the base station of a stop state returns to the operation state which can communicate. It is a figure showing the transmission timing of the control channel of an adjacent base station. It is a figure showing the transmission timing of the control channel of a self-station and an adjacent base station. It is a figure for demonstrating the process which determines a base station as a halt condition. It is a figure for demonstrating the process which determines with the base station determined to be a halt condition having returned to the operation state. It is a flowchart showing the control procedure of the standby zone selection level and standby zone holding | maintenance level of the wireless base station of 1st Embodiment. It is a figure showing the structure of the wireless base station of 2nd Embodiment.

Embodiments of the present invention will be described below with reference to the drawings.
[First Embodiment]
In the first embodiment, an existing PHS base station will be described as an example.

(Constitution)
FIG. 1 is a diagram showing a configuration of a wireless communication system according to an embodiment of the present invention.

  Referring to FIG. 1, this radio communication system includes a base station control center 31, a plurality of radio base stations 1-1 to 1-N, and radio terminals 32-1 to 32-2 that communicate with these radio base stations. 3. The base station control center 31 and the plurality of radio base stations 1-1 to 1-N are connected by wired networks 30-1 to 30-N. Hereinafter, the wireless base stations 1-1 to 1-N are collectively referred to as the wireless base station 1, the networks 30-1 to 30-N are collectively referred to as the network 30, and the wireless terminals 32-1 to 32-32. -3 may be collectively referred to as a wireless terminal 32.

FIG. 2 is a diagram illustrating the configuration of the radio base station according to the first embodiment.
Referring to FIG. 2, this radio base station 1 includes an antenna 10, a radio communication unit 2, a received power measurement unit 3, a timing control unit 4, a call channel management unit 5, a control channel management unit 6, The determination unit 21, the standby level control unit 7, the adjacent base station ID storage unit 8, and the stop base station ID storage unit 9 are provided.

The wireless communication unit 2 transmits and receives wireless signals through the antenna 10.
The received power measuring unit 3 measures the power of the received signal received by the wireless communication unit 2.

  The timing control unit 4 instructs the control channel management unit 6 about the transmission timing of the control channel, and instructs the call channel management unit 5 about the timing of transmission and reception of the call channel.

  The determination unit 21 monitors the control channel of the adjacent base station and grasps the operation status of the adjacent base station. Specifically, the determination unit 21 is in a stopped state in which the adjacent base station is incapable of communication when the control channel transmitted from the adjacent base station cannot be continuously received a predetermined number of times or more. Is determined. When the control unit transmitted from the neighboring base station in the stopped state can be continuously received a predetermined number of times or more, the determining unit 21 determines that the neighboring base station in the stopped state has been restored to the operable state. .

  The standby level control unit 7 decreases the standby zone selection level and the standby zone holding level of its own station when the adjacent base station is in a stopped state where communication is impossible. Further, the standby level control unit 7 increases the reduced standby zone selection level and standby zone holding level of the own station to the original levels when the neighboring base station in the stopped state is restored to an operable state. .

  Here, the standby zone selection level represents a threshold of a reception level at which the wireless terminal first enters a standby state. When this standby zone selection level is increased, the standby area is reduced, but the communication quality at the end of the area is improved. Conversely, if the standby zone selection level is reduced, the standby area increases, but the communication quality at the edge of the area deteriorates.

  The standby zone holding level represents a reception level threshold value for maintaining standby after the wireless terminal selects a connection destination base station. By having the standby zone holding level, it is possible to prevent frequent switching of out-of-service / standby at the wireless terminal at the edge of the area. In order for the wireless terminal to hold standby, the standby zone holding level is preferably a value equal to or lower than the standby zone selection level. If the standby zone retention level is reduced, the standby area increases, but the communication quality at the edge of the area deteriorates. Conversely, if the standby zone holding level is increased, calls cannot be made even in the standby state.

  The area defined by the conventional default standby zone selection level and standby zone retention level is set narrower than the area where radio waves actually reach for stable communication. That is, the conventional default standby zone selection level and standby zone retention level are set to values that are somewhat larger than the limit over which radio waves actually reach.

  This is because when the standby zone selection level and the standby zone holding level are set to the limits of the area where radio waves actually reach, there is a problem that out-of-service / standby switching is frequently performed at the wireless terminal at the area edge, and This is because there is a problem that it is easy to receive interference from adjacent base stations.

  Therefore, the radio terminal can receive radio waves from the base station even if the standby zone selection level and the standby zone holding level are slightly reduced from the default. In addition, when the adjacent base station stops communication, it does not receive interference from the adjacent base station at the end of the area.

  In the embodiment of the present invention, when the adjacent base station stops communication, the standby zone selection level and the standby zone holding level of the own station (own radio base station) are reduced by utilizing such characteristics. By doing so, the communication area of the neighboring base station in the stopped state is covered.

The adjacent base station ID storage unit 8 stores a CS-ID that is an identification number of the adjacent base station.
The stopped base station ID storage unit 9 stores the CS-ID of the base station determined to be in the stopped state.

  The control channel management unit 6 manages transmission of the control channel according to the timing instructed from the timing control unit 4. The control channel management unit 6 notifies the standby zone selection level and the standby zone holding level using a broadcast channel that is a type of control channel.

  The call channel management unit 5 manages transmission and reception of the call channel according to the timing instructed from the timing control unit 4.

(Within communication area)
FIG. 3A is a diagram illustrating the communication area before the wireless base station enters a stop state where communication is impossible.

  As shown in FIG. 3A, the wireless base station # 1, the wireless base station # 2, and the wireless base station # 3 can communicate with wireless terminals within the communication area areas 52, 55, and 54, respectively.

  FIG. 3B is a diagram for explaining a communication area area when a certain radio base station is in a stopped state where communication is impossible.

  As shown in FIG. 3B, when the wireless base station # 2 is in a stop state where communication is impossible, the standby zone selection level and the standby zone holding level of the wireless base station # 1 and the wireless base station # 3 are set. Decrease. As a result, the communication area area 52 of the wireless base station # 1 is expanded to the communication area area 51, and the communication area area 54 of the wireless base station # 3 is expanded to the communication area area 53.

  FIG. 3C is a diagram for explaining the communication area area when the wireless base station in a stopped state returns to an operable state. By returning to the operation state in which the radio base station # 2 can communicate, the standby zone selection level and the standby zone holding level of the radio base station # 1 that has determined that the radio base station # 2 is in the stopped state are increased to the original levels Then, the communication area area 51 returns to the original communication area area 52. Further, the standby zone selection level and the standby zone holding level of the wireless base station # 3 that has determined that the wireless base station # 2 is in the stopped state increase to the original level, and the communication area area 53 returns to the original communication area area 54.

(Control channel timing)
FIG. 4 is a diagram illustrating the transmission timing of the control channel of the adjacent base station.

  As shown in FIG. 4, adjacent base station # 1 and adjacent base station # 2 transmit a control channel at a period of 100 msec at different timings.

FIG. 5 is a diagram showing the transmission timing of the control channel of the own station and the adjacent base station.
As shown in FIG. 5, the own station (that is, the radio base station) transmits the control channel at a cycle of 100 msec at a timing different from the transmission timing of the control channel of adjacent base station # 1 and adjacent base station # 2. To control.

FIG. 6 is a diagram for explaining a process of determining a base station to be in a stopped state.
As shown in FIG. 6, reception of the control channel from the adjacent base station # 2 has failed continuously five times (1) to (5). As a result, the adjacent base station # 2 is determined to be in a stopped state.

  FIG. 7 is a diagram for explaining a process of determining that the base station determined to be in the stopped state has returned to the operating state.

  As shown in FIG. 7, the control channel has been successfully received from the stopped base station # 2 for five consecutive times (1) to (5). As a result, it is determined that the stopped base station # 2 has returned to the operating state.

(Operation)
FIG. 8 is a flowchart showing a control procedure of the standby zone selection level and the standby zone holding level of the radio base station according to the first embodiment.

  Referring to FIG. 8, when the power is turned on (step S101), standby level control unit 7 sets a radio base station whose reception level measured by reception power measurement unit 3 is a predetermined value (for example, 30 dB) or more to an adjacent base station. The CS-ID of the set adjacent base station is stored in the adjacent base station ID storage unit 8 (step S102).

  Next, the timing control unit 4 causes the control channel management unit 6 to transmit its own control channel at a cycle of 100 msec at a timing different from the timing at which the adjacent base station storing the CS-ID transmits the control channel. (Step S103).

  Next, when there is a radio base station that has not been able to continuously receive the control channel five times (that is, for 500 msec) among the adjacent base stations that store the CS-ID, the determination unit 21 (step S104). ), Determines that the adjacent base station is in a stopped state, and stores the CS-ID of the adjacent base station in the stopped state in the stopped base station ID storage unit 9 (step S105).

  The standby level control unit 7 decreases the standby zone selection level from, for example, 50 dB to 30 dB, and decreases the standby zone holding level from, for example, 30 dB to 10 dB (step S106).

  The control channel management unit 6 notifies the wireless terminal of the reduced standby zone selection level and standby zone retention level using the broadcast channel. When there is a change in the standby zone selection level and the standby zone holding level notified by the received broadcast channel, the wireless terminal changes the standby zone selection level and the standby zone holding level (step S107).

  Next, when there is a radio base station that has received the control channel five times continuously among the neighboring base stations in the stopped state that store the CS-ID (step S108), the determination unit 21 stops the state. Is determined to have returned to the operating state, and the CS-ID of the determined adjacent base station is deleted from the stopped base station ID storage unit 9 (step S109).

  The standby level control unit 7 returns the standby zone selection level from 30 db to the original 50 dB, and returns the standby zone retention level from 10 dB to the original 30 dB (step S110).

  The control channel management unit 6 notifies the wireless terminal of the standby zone selection level and standby zone retention level that have been increased to the original level using the broadcast channel (step S111).

  As described above, according to the present embodiment, an adjacent base station of a wireless base station that has been in a stopped state where wireless signals cannot be communicated changes the standby zone selection level and the standby zone holding level to the wireless terminal. By notifying, an adjacent base station can cover an area that has conventionally been out of service and can communicate. As a result, the area covered by the wireless base station that has been stopped can be covered before the wireless base station that has been stopped is restored, so that communication services can be provided without any delay. . In particular, according to the embodiment of the present invention, even when one radio base station breaks down at the time of disaster occurrence, there is an advantage that it is possible to reduce the situation where it is impossible to contact in an emergency.

  In the embodiment of the present invention, since the area is expanded without changing the transmission output of the radio base station, the service area of the radio base station that has been stopped is adjacent to the adjacent area without increasing interference between the radio base stations. It becomes possible to cover temporarily with the base station.

  Further, in the embodiment of the present invention, when a radio base station that has been in a stopped state is restored to an operating state, an adjacent base station that has covered the area of the radio base station that has been in a stopped state, It can be returned to the cover area.

[Second Embodiment]
The second embodiment is applicable to a wireless communication system such as LTE (Long Term Evolution) designed so that cells do not overlap. If the cells do not overlap, the control channel of the adjacent base station cannot be acquired. Therefore, as in the first embodiment, the adjacent base station is stopped by monitoring the radio control channel. I can't figure out. Therefore, in the second embodiment, a base station that is in a stopped state where communication is impossible transmits a message indicating that the base station is in a stopped state to the base station control center 31 through the network 30. The wireless base station that has returned to the communicable operating state transmits a message to the effect that the wireless base station has returned to the operating state to the base station control center 31 via the network 30.

FIG. 9 is a diagram illustrating a configuration of a radio base station according to the second embodiment.
The wireless base station 11 is different from the wireless base station 1 of the first embodiment in FIG. 2 in that it includes a network communication unit 13 and a function of the determination unit 22.

  The network communication unit 13 receives a notification from the base station control center 31 that the adjacent base station is in a stopped state through the network 30. In addition, the network communication unit 13 receives notification from the base station control center 31 through the network 30 that the stopped neighboring base station has been restored to the operating state.

  The determination unit 22 receives a notification that the adjacent base station is in the stopped state through the network communication unit 13, and determines that the adjacent base station is in the stopped state.

  The determination unit 22 receives a notification that the neighboring base station in the stopped state has recovered to the operating state through the network communication unit 13, and determines that the neighboring base station in the stopped state has recovered to the operating state.

As described above, the present embodiment can provide the same effects as those of the first embodiment.
[Modification]
The present invention is not limited to the above embodiment, and includes, for example, the following modifications.

(1) Standby zone selection level and standby zone retention level In the embodiment of the present invention, both the standby zone selection level and the standby zone retention level are changed according to whether or not the control channel has been successfully received. However, it is good also as changing only any one.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1, 11 radio base station, 2 radio communication unit, 3 received power measurement unit, 4 timing control unit, 5 call channel management unit, 6 control channel management unit, 7 standby level control unit, 8 adjacent base station ID storage unit, 9 Stop base station ID storage unit, 10 antenna, 13 network communication unit, 21, 22 determination unit.

Claims (10)

A standby level control unit that reduces the standby zone selection level and / or standby zone holding level of the own station when the adjacent base station is in a communication stop state;
A radio base station comprising: a notification unit that notifies the radio terminal of the reduced standby zone selection level and / or standby zone retention level. The radio base station further includes:
The radio base station according to claim 1, further comprising: a determination unit configured to determine whether or not the adjacent base station is in a stopped state in which communication is not possible based on a control channel transmitted from the adjacent base station at a constant period.   The said determination part determines that the said adjacent base station is a stop state, when the control channel transmitted with the fixed period from the said adjacent base station cannot be received continuously more than predetermined times. Wireless base station. The radio base station is
The radio base station according to claim 1, further comprising: a determination unit that receives a notification that the adjacent base station is in a stopped state from a center that manages the base station and determines that the adjacent base station is in a stopped state. The standby level control unit restores the reduced standby zone selection level and / or standby zone holding level of the local station to the original level when the neighboring base station in the stopped state is restored to an operable state. Increase,
The radio base station according to claim 1, wherein the notification unit notifies the radio terminal of the standby zone selection level and / or the standby zone holding level increased to the original level. The radio base station further includes:
The determination unit according to claim 5, further comprising: a determination unit configured to determine whether or not the neighboring base station in the stopped state has been restored to the operating state based on a control channel transmitted from the neighboring base station in the stopped state at a constant period. Radio base station.   The determination unit determines that the adjacent base station in the stopped state has been restored to the operating state when the control channel transmitted from the adjacent base station in the stopped state has been continuously received a predetermined number of times or more. The radio base station according to claim 6. The radio base station is
From the center that manages the base station, a determination unit that receives a notification that the neighboring base station in the stopped state has been restored to the operating state and determines that the neighboring base station in the suspended state has been restored to the operating state, The radio base station according to claim 5. The radio base station is a PHS base station,
The radio base station according to claim 1, wherein the notification unit notifies the radio terminal of the standby zone selection level and / or the standby zone holding level using a broadcast channel. Reducing the standby zone selection level and / or the standby zone holding level of the local station when the adjacent base station is in a communication stop state,
And notifying the wireless terminal of the reduced standby zone selection level and / or standby zone retention level.

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