This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2010-188184, filed on Aug. 25, 2010, the entire contents of which are incorporated herein by reference.
Embodiments discussed herein are related to a control station and a control method for controlling a radio base station, and to a radio communication system that includes the radio base station, the control station, and the like.
In the radio communication system such as a mobile phone system, the control station monitors or controls, for example, a plurality of radio base stations. Each of the plurality of radio base stations performs radio communication with a mobile terminal positioned inside a communication area (for example, a cell or a sector) covered by the plurality of radio base stations.
In the above-described radio communication system, if an error occurs in the radio base station (for example, if an event obstructs an operation, which is normal or stable, or obstructs the operation in the future), the mobile terminal, positioned inside the communication area of the radio base station in which the error occurs, has difficulty maintaining the radio communication or starting another radio communication.
According to an aspect of the embodiments discussed herein, a radio communication system includes a plurality of radio base stations, and a control station which controls the plurality of radio base stations, wherein the control station comprises a controller which determines a peripheral base station, from among a plurality of peripheral base stations, and which adjusts a radio parameter for changing a range of a communication area based on each load of the plurality of peripheral base stations which are adjacent or close to a radio base station to be relieved from among the plurality of radio base stations.
Additional objects and advantages of the embodiments will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the embodiments. The object and advantages of the embodiments will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the embodiments, as claimed.
Embodiments will be described with reference to the attached diagrams. Hereinafter, a mobile phone system will be described as an example of the radio communication system. The embodiments described below are applicable to various radio communication systems other than the mobile phone system.
(1) Configuration of Radio Communication System
With reference to
As illustrated in
For example, the monitor control station 10 sets and opens channels for each speech communication of a plurality of radio base stations 20 positioned under the monitor control station 10 and controls handover of the mobile terminal 30 positioned inside a cell 29 (e.g., 29a or 29b) of each of the plurality of radio base stations 20 positioned under the monitor control station 10.
According to the first embodiment, when an error occurs in the radio base station 20, the monitor control station 10 controls the operation of the plurality of radio base stations 20 (hereinafter referred to as a “peripheral base station 20”) positioned in periphery of the radio base station 20 (hereinafter referred to as an “error base station 20”) in which the error occurs. For example, an “error” is an example of an event (for example, a hardware error, operation runaway, or operation suspension) that obstructs the operation, which is normal or stable, of the radio base station 20. Alternatively, the “error” according to the first embodiment is an example of an event (for example, detection or the like of an abnormal value (or a value other than acceptable values) of various parameters indicating an operation state of the radio base station 20) that may obstruct the operation, which is normal or stable, of the radio base station 20. More specifically, the monitor control station 10 controls the operation of the plurality of peripheral base stations 20 so that the cell 29 (for example, a range that is the cell 29 before the error occurs) of the error base station 20 is compensated (that is, relieved or covered) by the plurality of peripheral base stations 20. The control of the peripheral base station 20 by the monitor control station 10 will be described below (see
The radio base station 20 covers the cell 29 (a so-called macrocell) of which the radius is approximately several kilometers to more than ten kilometers or several tens of kilometers. The radio base station 20 performs the radio communication with the mobile terminal 30 included in the radio base station 20 (that is, the mobile terminal 30 is positioned inside the cell covered by the radio base station 20). That is, the radio base station 20 establishes a communication connection with the mobile terminal 30 included in the radio base station 20 and transmits and receives data to and from the mobile terminal 30.
The mobile terminal 30 establishes a communication connection with the radio base station 20 corresponding to the cell 29, in which the mobile terminal 30 is positioned, and transmits and receives the data. The mobile terminal 30 may use various services and applications (for example, a mail service, a speech communication service, a WEB browsing service, and the like) through the radio base station 20 (furthermore, a core network (not illustrated) positioned in an upper order of the monitor control station 10). A mobile phone, a Personal Digital Assistant (PDA), and various information apparatuses with radio communication functions are given as examples of the mobile terminal 30.
In the above description, the radio base station 20 covers the cell 29 (a so-called macrocell) of which the radius is approximately several kilometers to more than ten kilometers or several tens of kilometers. However, in addition to or instead of the radio base station 20, a radio base station that covers the cell (a so-called macrocell) of which the radius is approximately several hundred meters to one kilometer and a radio base station that covers the cell (a so-called femtocell) of which the radius is approximately several meters to more than ten meters may be used and/or allocated. Various radio base stations that cover the cell of which the radius does not have the above-described size may be used and/or allocated.
(2) Configuration of Monitor Control Station
With reference to
As illustrated in
The base station communication device 11 includes a receiver 111 that receives data transmitted from the radio base station 20, and a transmitter 112 that transmits the data to the radio base station 20.
The memory 12 stores traffic information such as a traffic amount of each of the plurality of radio base stations 20 positioned under the monitor control station 10. The traffic amount stored in the memory 12 is included, for example, in control data transmitted from each of the plurality of radio base stations 20 to the monitor control station 10. The number of the mobile terminals 30 included in each of the plurality of radio base stations 20, the data amount to be processed by each of the plurality of radio base stations 20, and the like are given as an example of the traffic amount.
The data processor 13, which is an example of a controller, controls operations of the monitor control station 10. The data processor 13 includes, for example, a traffic amount grasping section 131, a priority order determining section 132, a tilt angle control range determining section 133, and a relieving determining section 134 as a processing block that is logical or functional to be provided inside the data processor 13.
The traffic amount grasping section 131 obtains the traffic amount stored in the memory 12. For example, the traffic amount grasping section 131 obtains the traffic amount of the error base station 20 and of each of the plurality of peripheral base stations 20 if an error occurs in at least one of the plurality of radio base stations 20 positioned under the monitor control station 10. The traffic amount grasping section 131 outputs the obtained traffic amount of the error base station 20 to the relieving determining section 134. The traffic amount grasping section 131 outputs the obtained traffic amounts of the plurality of peripheral base stations 20 to the priority order determining section 132.
Based on the traffic amount of the plurality of peripheral base stations 20, the priority order determining section 132 determines the priority order for compensating the range that is the cell 29 of the error base station 20 with respect to each of the plurality of peripheral base stations 20. The priority order determining section 132 reports the determined priority order to the tilt angle control range determining section 133. In addition to or instead of determining the priority order of the peripheral base station 20, the priority order determining section 132 may determine the peripheral base station 20 that compensates the range that is the cell 29 of the error base station 20. In this case, the priority order determining section 132 may report the determined peripheral base station 20 to the tilt angle control range determining section 133.
According to the priority order reported from the priority order determining section 132, the tilt angle control range determining section 133 determines the control range that controls the tilt angle of the antenna element 251 (see
The relieving determining section 134 determines whether or not the determination standard for relieving the error base station 20 is satisfied by controlling the tilt angle of the antenna element 251 of the peripheral base station 20. A determination result is reported to, for example, the tilt angle control range determining section 133.
As illustrated in
(3) Configuration of Radio Base Station
With reference to
As illustrated in
The control station communication device 21 includes a receiver 211 that receives data transmitted from the monitor control station 10, and a transmitter 212 that transmits the data to the monitor control station 10.
The data processor 23 controls operations of the radio base station 20. The data processor 23 includes a traffic information collecting section 231 and a tilt angle control section 232 as a processing block, which is logical or functional, provided inside the data processor 23.
The traffic information collecting section 231 collects the traffic amount of the radio base station 20. The collected traffic amount is transmitted as a part of the control data, for example, to the monitor control station 10.
The tilt angle control section 232 operates the antenna actuator 252 according to the control range of the tilt angle transmitted from the monitor control section 10. As a result, for example, a motor or the like included in the antenna actuator 252 changes the tilt angle of the antenna element 251. Since the tilt angle is changed, the shape or the size of the radio base station 20 varies.
The mobile terminal communication device 24 receives the data (that is, an uplink signal) transmitted from the mobile terminal 30 and transmits the data (that is, a downlink signal) to the mobile terminal 30.
The antenna 25 outputs the radio signal (radio wave) according to the data, which is transmitted to the mobile terminal 30. The antenna 25 receives the radio signal output from the mobile terminal 30 (that is, the radio signal according to the data transmitted from the mobile terminal 30).
As illustrated in
(4) Operation Example
With respect to
As illustrated in
According to the determination result from Operation S11, if no error occurs (NO in Operation S119), the monitor control station 10 repeats Operation S11.
According to the determination result from Operation S11, if the error occurs (YES in Operation S119), the traffic amount grasping section 131 included in the monitor control station 10 obtains the traffic amount of the error base station 20 before the error occurs (Operation S12). The traffic amount grasping section 131 included in the monitor control station 10 obtains each traffic amount of the plurality of peripheral base stations 20 (Operation S13).
Based on each traffic amount of the plurality of peripheral base stations 20 obtained in Operation S13, the priority order determining section 132 included in the monitor control station 10 determines the priority order for compensating the range that is the cell 29 of the error base station 20 with respect to each of the plurality of peripheral base stations 20 (Operation S14). For example, the priority order determining section 132 may determine the priority order so that a higher priority order is assigned to the peripheral base station 20 having a lower traffic amount. That is, the priority order determining section 132 may determine the priority order so that the peripheral base station 20 having a larger traffic amount is assigned with a lower priority order. For example, the priority order determining section 132 may determine the priority order so that the peripheral base station 20 having a lower processing load is assigned with a higher priority order. That is, the priority order determining section 132 may determine the priority order so that a lower priority order is assigned to the peripheral base station 20 having a higher processing load.
With reference to
Based on the traffic amount of the peripheral base station 20,
In
With reference to
The tilt angle control range determining section 133 may determine the control range of the tilt angle so that the peripheral base station 20 having a higher priority order determined in Operation S14 covers a larger part or range of the cell 29 of the error base station 20. Alternatively, for example, the tilt angle control range determining section 133 may determine the control range of the tilt angle so that the peripheral base station 20 having a higher priority order determined in Operation S14 relieves more mobile terminals 30 that are stored (or were stored) in the error base station 20.
As illustrated in
Every time the tilt angle of the antenna element 251 included in one of the peripheral base stations 20 is controlled, the relieving determining section 134 determines whether or not the determination standard for relieving the error base station 20 is satisfied (Operation S17). For example, the relieving determining section 134 may determine whether or not a prescribed amount (for example, 90% of the traffic amount) of the traffic amount before the error occurrence in the error base station 20 is relieved. Alternatively, the relieving determining section 134 may determine whether or not a prescribed amount (for example, 90% of the mobile terminal 30) of the mobile terminal 30 stored in the error base station 20 is relieved. The traffic amount (that is, the mobile terminal 30) may be determined to be relieved or not by referring to position information (for example, GPS information) indicating the position of the mobile terminal 30 reported from the mobile terminal 30. If the position information indicating the position of the error base station 20 inside the cell 29 is reported from the mobile terminal 30 to the peripheral base station 20, the mobile terminal 30 is determined to be stored (that is, relieved) in the peripheral base station 20 by controlling the tilt angle. On the other hand, for example, if the position information indicating the position of the error base station 20 inside the cell 29 is not reported from the mobile terminal 30 to the peripheral base station 20, the mobile terminal 30 is determined not to be stored (that is, relieved) in the peripheral base station 20 by controlling the tilt angle. Since the determination is performed based on the position information, preferably the peripheral base station 20 reports the reception result of the position information from the mobile terminal 30 to the monitor control station 10. By referring to the reception result reported from the peripheral base station 20 and comparing a relieving state indicated by the reception result to the traffic amount of the error base station 20, the relieving determining section 134 may determine whether or not the determination standard of relieving is satisfied.
According to the result of the determination in Operation S17, if the determination standard for relieving is satisfied (YES in Operation S17), the monitor control station 10 preferably does not control the tilt angle corresponding to another peripheral base station 20 while maintaining the ongoing control of the tilt angle. For example, as illustrated in the example in
On the other hand, based on the determination result from Operation S17, if the determination standard for relieving is not satisfied (NO in Operation S17), the tilt angle control range determining section 133 determines whether or not the tilt angle with respect to all the peripheral base stations 20 is controlled (Operation S18). For example, as illustrated in
Based on the determination result from Operation S18, if the tilt angle with respect to all the peripheral base stations 20 is controlled (YES in Operation S18), the monitor control station 10 ends the operation. In this case, the monitor control station 10 may maintain or stop the ongoing control of the tilt angle (that is, the original state may return). If the determination standard for relieving is not satisfied when the tilt angle is performed with respect to the controlled peripheral base station 20, the error base station 20 is assumed not to be relieved. Therefore, the monitor control station 10 may report, to an operator of the error base station 20, that the peripheral base station 20 may not relieve the error base station 20.
Based on the determination result from Operation S18, if the tilt angle with respect to all of the peripheral base stations 20 is not controlled (NO in Operation S18), the tilt angle control range determining section 133 reports the control range of the tilt angle with respect to the peripheral base station 20 having the second highest priority order to the peripheral base station 20 having the second highest priority order (Operation S19). The control range of the tilt angle reported from the tilt angle control range determining section 133 is obtained by the tilt angle control section 232 included in the peripheral base station 20 having the second highest priority order. The tilt angle control section 232 controls the tilt angle of the antenna element 251 by operating the antenna actuator 252 according to the reported control range of the tilt angle (Operation S19).
The relieving determining section 134 determines whether or not the determination standard for relieving the error base station 20 is satisfied (Operation S17). A similar operation is repeated until the determination standard for relieving the error base station 20 is satisfied or until the control of the tilt angle with respect to all the peripheral base stations 20 is controlled.
According to the radio communication system 1 of the first embodiment, the range that is the cell 29 of the error base station 20 may be compensated in consideration of the traffic amount of the peripheral base station 20. According to the radio communication system 1 of the first embodiment, compared to the radio communication system that compensates the range that is the cell 29 of the error base station 20 without consideration of the traffic amount of the peripheral base station 20, the range that is the cell 29 of the error base station 20 may preferably be compensated. That is, the error base station 20 may be preferably relieved.
Here, as compared with the radio communication system 1 of the first embodiment, an example of a radio communication system relating to conventional techniques is described. In the example of the radio communication system, the radio base station that compensates the range that is the communication area of the radio base station in which the error occurs is specified in advance by being set by, for example, an operator of the radio base station. In this case, the technical problem described below may occur according to the operation state of the radio base station that is specified in advance. Specifically, for example, the radio base station, which compensates the range that is the communication area of the radio base station in which the error occurs, processes not simply the traffic to be processed before compensating the range that is the communication area of the radio base station in which the error occurs but also the new traffic to be added after compensating the range that is the communication area of the radio base station in which the error occurs. Accordingly, if the traffic amount processed before the radio base station on the compensating side compensates the range is relatively large, the traffic amount to be proceeded after being compensated by the radio base station may exceed the acceptable value. In this case, the radio communication of the mobile terminal positioned in the cell of the radio base station on the compensating side may be interrupted. The above-described technical problem may occur when the load of the radio base station is relatively large regardless of the traffic amount of the radio base station. Furthermore, the above-described technical problem may occur not simply when the range that is the communication area of the radio base station in which the error occurs is compensated, but also when another radio base station compensates the communication area (or the range that is the communication area) of a specific radio base station.
In contrast, according to the radio communication system 1 of the first embodiment, the range that is the cell 29 of the error base station 20 may preferably be compensated. That is, the error base station 20 may preferably be relieved.
According to the radio communication system 1 of the first embodiment, the peripheral base station having a lower traffic amount may compensate a larger part of the range that is the cell 29 of the error base station 20. Therefore, for example, exceeding the acceptable value of the traffic amount of the peripheral base station 20 due to the compensating may be suppressed.
According to the radio communication system 1 of the first embodiment, the tilt angle may be controlled in the descending order from the peripheral base station 20 having a small traffic amount. For example, the occurrence of exceeding of the acceptable value of the traffic amount of the peripheral base station 20 is preferably suppressed when the peripheral base station 20 having a large traffic amount first compensates the range that is the cell 29 of the error base station 20.
According to the radio communication system 1 of the first embodiment, the tilt angle with respect to the peripheral base station 20 may be controlled with reference to the traffic amount before the error occurrence in the error base station 20. Therefore, the tilt angle with respect to the peripheral base station 20 may be controlled so that the traffic amount before the error occurrence in the error base station 20 may be properly compensated.
According to the radio communication system 1 of the first embodiment, every time the tilt angle with respect to one of the peripheral base stations 20 is controlled, determination may be made to indicate whether or not the determination standard for relieving is satisfied. If the determination standard for relieving is not satisfied, the tilt angle with respect to the peripheral base station 20 having the second highest priority order is controlled. Therefore, the tilt angle of an excessively large number of the peripheral base stations 20 being controlled is unlikely.
According to the radio communication system 1 of the first embodiment, the priority order may be added to each of the plurality of peripheral base stations 20. Therefore, with reference to the added priority order, the control range of the tilt angle may be easily determined in a proper order, and the tilt angle may be controlled.
According to the first embodiment, the control of the tilt angle of the antenna element 251 included in the radio base station 20 is given as an example of a control method for compensating the range that is the cell 29 of the error base station 20. However, the range that is the cell 29 of the error base station 20 may be compensated by using a method other than the control of the tilt angle of the antenna element 251. For example, the tilt angle control range determining section 133 included in the monitor control station 10, and the tilt angle control section 232 and the antenna actuator 252 or the like included in the radio base station 20 may be changed according to a different employed method (that is, the method other than the control of the tilt angle). For example, the range that is the cell 29 of the error base station 20 may be compensated by controlling a parameter that affects beam forming of a radio wave emitted from the antenna element 251. For example, the range that is the cell 29 of the error base station 20 may be compensated by controlling the transmission power of the peripheral base station 20. Alternatively, the range that is the cell 29 of the error base station 20 may be compensated by controlling a reception power threshold value at handover to the peripheral base station 20.
The first embodiment describes an example of a case where the cell 29 of the error base station 20 in which the error occurs is compensated. However, when the peripheral base station 20 compensates the cell 29 of the radio base station 20 in which the error does not occur but the error may occur in the future, the configuration and operations of the above-described embodiments may be employed. Alternatively, to compensate the cell 29 of the radio base station 20 that is specific, desired, or arbitrary by the peripheral base station 20 regardless of the error occurrence, the configurations and operations of the above-described embodiments may be employed. In the above-described configuration, the above-described various effects may be achieved.
(5) Modified Operation
With reference to
As illustrated in
Based on the determination result from Operation S11, if no error occurs (NO in Operation S11), the monitor control station 10 repeats Operation S11.
Based on the determination result from Operation S11, if an error occurs (YES in Operation S11), the traffic amount grasping section 131 included in the monitor control station 10 obtains the traffic amount of the error base station 20 before the error occurrence (Operation S12). Furthermore, the traffic amount grasping section 131 included in the monitor control station 10 obtains each traffic amount of the plurality of peripheral base stations 20 (Operation S13).
Based on each traffic amount of the plurality of peripheral base stations 20 obtained in Operation S13, the priority order determining section 132 included in the monitor control station 10 determines the priority order to compensate the range that is the cell 29 of the error base station 20 with respect to each of the plurality of peripheral base stations 20 (Operation S14).
In the modified operation example, the relieving determining section 134 selects the peripheral base station 20, which has the highest priority order, as a candidate that compensates the range that is the cell 29 of the error base station 20 (Operation S21). The relieving determining section 134 predicts whether or not the error base station 20 is relieved when all the peripheral base stations 20 that have been selected compensate the range that is the cell 29 of the error base station 20 (Operation S22). The relieving determining section 134 may predict whether or not the error base station 20 is relieved based on the empty traffic amount (that is, the traffic amount that may further be stored) of the peripheral base station 20 and the traffic amount before the error occurrence in the error base station 20. For example, the relieving determining section 134 may calculate the empty traffic amount of the peripheral base station 20 by referring to the traffic amount of the peripheral base station 20. The relieving determining section 134 may determine whether or not the total empty traffic amount of the selected peripheral base station 20 exceeds a prescribed amount (for example, 90% of the traffic amount) of the traffic amount of the error base station 20 before the error occurrence. If the total empty traffic amount of the selected peripheral base station 20 exceeds the prescribed amount of the traffic amount of the error base station 20 before the error occurrence in the error base station 20, the error base station 20 is predicted to be relieved. On the other hand, if the total empty traffic amount of the selected peripheral base station 20 does not exceed the prescribed amount of the traffic amount before the error occurrence in the error base station 20, the error base station 20 is predicted not to be relieved.
Based on the determination result from Operation S21, if the error base station 20 is predicted not to be relieved (NO in Operation S22), the relieving determining section 134 determines whether or not all the peripheral base stations 20 are selected as a candidate that compensates the range that is the cell 29 of the error base station 20 (Operation S24).
Based on the determination result from Operation S24, if all the peripheral base stations 20 are selected as a candidate that compensates the range that is the cell 29 of the error base station 20 (YES in Operation S24), the monitor control station 10 ends the operation. That is, the monitor control station 10 ends the operation without controlling the tilt angle with respect to the peripheral base station 20. The monitor control station 10 may report that the peripheral base station 20 may not relieve the error base station 20 to the operator of the error base station 20.
On the other hand, based on the determination result from Operation S24, if the all the peripheral base stations 20 are not selected as a candidate that compensates the range that is the cell 29 of the error base station 20 (NO in Operation S24), the relieving determining section 134 selects the peripheral base station 20 having the second highest priority order as a candidate that compensates the range that is the cell 29 of the error base station 20 (Operation S25). The relieving determining section 134 determines whether or not the error base station 20 may be relieved if all the selected peripheral base stations 20 compensate the range that is the cell 29 of the error base station 20 (Operation S22). The similar operation is repeated until the error base station 20 is determined to be relieved or until all the peripheral base stations 20 are selected.
On the other hand, based on the determination result from Operation S21, if the error base station 20 is predicted to be relieved (YES in Operation S22), the tilt angle control range determining section 133 determines the control range, which controls the tilt angle of the antenna element 251 included in each of the peripheral base stations 20 selected in Operation S21 and Operation S25, according to the priority order reported from the priority order determining section 132 (YES in Operation S22). The method for determining the control range of the tilt angle in Operation S22 may be equivalent to the method for determining the control range of the tilt angle in Operation S15 illustrated in
With reference to
In
The relieving determining section 134 determines whether or not the determination standard for relieving the error base station 20 is satisfied (Operation S17) when the tilt angle of the antenna element 251 included in one of the peripheral base stations 20 is adjusted or controlled.
Based on the determination result from Operation S17, if the determination standard for relieving the error base station 20 is satisfied (YES in Operation S17), the monitor control station 10 does not control the tilt angle with respect to another peripheral base station 20 while maintaining the ongoing control of the tilt angle.
On the other hand, based on the determination result from Operation S17, if the determination standard for relieving the error base station 20 is not satisfied (NO in Operation S17), the tilt angle control range determining section 133 reports the control range of the tilt angle corresponding to the peripheral base station 20 having the second highest priority order to the peripheral base station 20 having the second highest priority order (Operation S19). The relieving determining section 134 determines whether or not the determination standard for relieving the error base station 20 is satisfied (Operation S17). A similar operation is repeated until the determination standard for relieving the error base station 20 is satisfied or until the tilt angle with respect to all the peripheral base stations 20 is controlled.
In the modified operation, if the error base station 20 is predicted to be relieved by the peripheral base station 20, the tilt angle with respect to the peripheral base station 20 is actually controlled. Accordingly, there is rarely a state where the determination standard for relieving is not satisfied when the tilt angle with respect to all the peripheral base stations 20 is controlled. In the modified operation, the determination operation in Operation S18 illustrated in
As described above, according to the modified operation, the above-described various effects may be achieved. In addition, according to the modified operation, if the error base station 20 is predicted to be relieved by the peripheral base station 20, the tilt angle is actually controlled. Therefore, if the error base station 20 is not predicted to be relieved by the peripheral base station 20, the tilt angle may be unlikely to be actually controlled. Therefore, the processing load related to the control of the tilt angle by the monitor control station 10 and the peripheral base station 20 may be relatively reduced. According to the above-described radio communication system, the peripheral base station that varies the communication area may be determined in consideration of the load of the peripheral base station.
All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. Although the embodiments have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.
Number | Date | Country | Kind |
---|---|---|---|
2010-188184 | Aug 2010 | JP | national |