JP2009124461A - Radio base station and radio communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that, when the number of connected mobile radio terminals remarkably increases in a specific radio base station among a plurality of radio base stations in a radio communication system, the number of connected terminals is reduced by reducing the beacon signal power of the radio base station, however, accompanied by the reduction of the number of connected terminals, mobile radio terminals connected with other radio base station adjacent to the radio base station at long distance are generated, and in the mobile radio terminals, the sharp deterioration of radio communication quality is generated. <P>SOLUTION: Pieces of information regarding radio communication states of the respective radio base stations 111, 112 are shared by mutual communication, and the transmission power of a beacon signal transmitted from a local station and radio transmission speed of mobile radio terminals 121-124 connected to the local station are controlled using the shared information. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a radio base station and a radio communication having a function of averaging the number of mobile radio terminals connected to each radio base station when a plurality of radio base stations communicate with a plurality of mobile radio terminals. About the system.

  In recent years, with the advancement of digital wireless communication technology, wireless communication systems capable of high-speed transmission have been widely used in businesses and general households. Typical examples include wireless LAN systems such as IEEE802.11a, 11b, 11g, and 11n.

  When these wireless communication systems are used in corporations, large stores, various large facilities, or relatively large areas outside, to increase the number of mobile wireless terminals to be accommodated and to expand the area where radio waves reach In order to do so, a plurality of radio base stations are installed in a distributed manner in a plane. On the other hand, in order to move within the above-mentioned buildings and areas, the mobile radio terminal continues communication while selectively switching the radio base station with the best communication conditions.

  As is well known, these base station selections are performed using a connection control signal called a beacon signal transmitted from each radio base station. That is, the mobile radio terminal functions to detect the reception strength of beacon signals from a plurality of radio base stations, select the radio base station having the highest strength, and perform stable radio communication. If frequent base station connection switching (handover) is not preferable as the mobile radio terminal moves, a slight hysteresis may be set in the above signal strength comparison. There is no change in the judgment itself.

  However, there is a possibility that a big problem occurs in the above-described method. When one wireless base station communicates with a plurality of mobile wireless terminals, a constant wireless communication speed is distributed to the plurality of wireless terminals, so that the communication speed naturally decreases in inverse proportion to the number of connected terminals. Furthermore, since each mobile radio terminal normally transmits an access request to find the radio radio stop time and secure the radio communication time for itself, the collision probability of the access request signal rapidly increases as the number increases. As a result, the delay until establishment of a communication opportunity increases, and as a result, the communication speed is further reduced more than the inverse proportion of the number.

  Therefore, it is desirable to average the communication load so that the number of mobile radio terminals accommodated by each radio base station does not greatly deviate from one base station to another. It can be said that the base station selection based on the above-mentioned beacon signal strength is a method that cannot meet this requirement at all.

  To solve this problem, a method has been proposed in which the communication load between wireless base stations is averaged (see, for example, Patent Document 1 and Patent Document 2).

  In Patent Literature 1, each wireless base station notifies the mobile wireless terminal of its own communication status (for example, communication load information such as communication speed that can be provided to the mobile wireless terminal). It is described that it is easy to select a low-load radio base station by comparing the communication status information.

Patent Document 2 describes a method in which a radio base station with a large communication load reduces the power of a beacon signal to be transmitted, and conversely, a station with a margin in communication load increases the power of a beacon signal. As a result, even if the wireless mobile terminal is actually a close wireless base station, the wireless base station crowded with a large number of terminals reduces the beacon power, thus increasing the possibility of selecting another wireless base station. Is possible.
JP 2003-324449 A JP 2006-60322 A

  Although the above-mentioned Patent Document 1 and Patent Document 2 each present a solution for solving the load distribution of a radio base station, practical problems remain. First, in Patent Document 1, a new mechanism for transmitting a communication load status of a radio base station to a mobile radio terminal must be prepared, and an additional cost burden is generated in both the radio base station and the mobile radio terminal. In addition, radio base stations and mobile radio terminals introduced with the above-described mechanisms can be expected to operate appropriately, but existing mobile radio terminals do not react, and there is a risk of malfunction with respect to new protocols. Of course, because new terminals and existing terminals cannot be mixed, there is an introduction barrier that all radio base stations and mobile radio terminals must be exchanged at the same time in facilities that already operate radio communication systems. To do.

  Further, in Patent Document 2, the apparent distance from each mobile radio terminal to the radio base station is changed by the intensity control of the beacon signal. Therefore, the number of mobile radio terminals connected to the radio base station can be effectively increased or decreased. I can expect to do it. Further, since the mobile radio terminal only needs to operate with the conventional base station selection algorithm, there is a great advantage that the existing terminal can be used as it is.

  However, the method of Patent Document 2 causes a new problem. A mobile radio terminal that originally communicated with a radio base station with the best conditions is a radio base station that has not been selected until now due to a decrease in the beacon signal of the station, or a radio base station with poor communication conditions. Will start communication. As a result, there arises a problem that the possibility of impairing normal communication is increased due to an increase in communication errors accompanying a decrease in wireless transmission quality. Originally, in order to provide the highest reach and communication speed, each radio base station transmits at the maximum power within the communication standard in the normal operation state, and the beacon signal strength of the adjacent radio base station has decreased. Therefore, it is impossible to further increase the transmission power (both beacon signal and data communication signal) of the own station.

  The present invention has been made to solve the above problems, and for mobile communication terminals that are to communicate with distant base stations in order to average the communication load of a plurality of wireless base stations, An object of the present invention is to provide a radio base station and a radio communication system that reduce deterioration of communication quality.

  To achieve the above object, a radio base station according to the present invention is a communication system including at least a plurality of radio base stations and a plurality of mobile radio terminals that communicate with any of the radio base stations. When functioning to select a wireless base station to be connected by comparing the received power of beacon signals transmitted by a plurality of wireless base stations, the wireless base station determines its own station according to the number of mobile wireless terminals connected to it. The transmission power of the beacon signal emitted from the mobile station and the wireless transmission speed of the mobile wireless terminal connected to the own station are controlled. As a result, it is possible to control the number of mobile radio terminals in a plurality of radio base stations in the direction of averaging, and for mobile radio terminals that are to be connected to radio base stations farther than before the control. Thus, it is possible to provide a method for reducing deterioration in communication quality. In addition, since it is not necessary to add a new function or circuit to the mobile radio terminal, there is a feature that the existing mobile radio terminal can be used as it is.

  In addition, the radio base station of the present invention increases the transmission power of the beacon signal emitted from the own base station when the number of mobile radio terminals connected to the own base station is less than a predetermined threshold. It is desirable to control so as to reduce the wireless transmission rate with the mobile wireless terminal connected to the mobile phone. As a result, the configuration of the wireless communication system can be simplified because it is not necessary to share information between the wireless base stations by simply setting the threshold of the number of connected mobile wireless terminals that increase the transmission power of the beacon signal in each wireless base station in advance. Can be

  Also, the radio base station of the present invention shares information related to the radio communication status of each radio base station by mutual communication, and uses this shared information to connect the transmission power of the beacon signal emitted from the own station and the own station. The wireless transmission rate with the mobile wireless terminal may be controlled. Thereby, since the wireless communication status can be shared between the wireless base stations in real time, finer control becomes possible.

  In the radio base station of the present invention, it is preferable that the information on the radio communication status of the radio base stations shared with each other includes the number information of mobile radio terminals connected to each radio base station and the power information of the beacon signal. As a result, each radio base station grasps the terminal connection status of the entire radio communication system, effectively controls the transmission power control of beacon signals for the purpose of averaging the number of mobile radio terminals connected to each radio base station, and moves Wireless transmission speed control with a wireless terminal becomes possible.

  The radio base station of the present invention controls the radio base station that reduces the number of connected mobile radio terminals to at least reduce the transmission power of the beacon signal, and increases the number of connected mobile radio terminals. The base station may be controlled to reduce at least the radio transmission rate with the mobile radio terminal. As a result, the radio base station that wants to reduce the number of mobile radio terminals to be connected can narrow the range to an apparently narrow communicable area, and as a result, the number of connected terminals can be reduced. On the other hand, the wireless base station located in the vicinity of the wireless base station where the power of the beacon signal is reduced is connected to a remote mobile wireless terminal that has not been connected so far, so the wireless transmission conditions are not good. However, it is possible to maintain stable communication with these mobile radio terminals by reducing the radio transmission speed.

  A wireless communication system of the present invention includes a plurality of wireless base stations, a plurality of mobile wireless terminals that wirelessly communicate with any of the wireless base stations, and a server device that is wired to the plurality of wireless base stations. When the wireless base station functions to select the wireless base station to be connected by comparing the received power of the beacon signal transmitted by the wireless base station, the server device displays the number information of the mobile wireless terminals connected to each of the wireless base stations. A base station control signal that is received from the base station and controls the transmission power of the beacon signal in each of the plurality of radio base stations and the radio transmission speed with the mobile radio terminal is generated based on the number information of the base station. Is transmitted to each radio base station. Thus, only the server device needs to derive the control method for the transmission power of the beacon signal and the wireless transmission rate of the mobile wireless terminal, and each wireless base station receives the base station control signal from the server device. Therefore, the processing load on the radio base station can be reduced.

  In the radio communication system of the present invention, the control signal controls the radio base station that reduces the number of mobile radio terminals to be connected to at least reduce the transmission power of the beacon signal, and determines the number of mobile radio terminals to be connected. For a radio base station to be increased, it may be a control signal for controlling at least a radio transmission rate with a mobile radio terminal. As a result, the radio base station that wants to reduce the number of mobile radio terminals to be connected can narrow the range to an apparently narrow communicable area, and as a result, the number of connected terminals can be reduced. On the other hand, the wireless base station located in the vicinity of the wireless base station where the power of the beacon signal is reduced is connected to a remote mobile wireless terminal that has not been connected so far, so the wireless transmission conditions are not good. However, it is possible to maintain stable communication with these mobile radio terminals by reducing the radio transmission speed.

  In the radio communication system of the present invention, the control signal increases at least the transmission power of the beacon signal and decreases the radio transmission rate with the mobile radio terminal for the radio base station that increases the number of connected mobile radio terminals. It may be a control signal for controlling the control. As a result, the radio base station that changes the transmission power of the beacon signal is the same as the radio base station that changes the radio transmission speed, and control becomes easier.

  According to the present invention, it becomes possible to control the number of connected mobile radio terminals in a plurality of radio base stations in a direction to be averaged, and to move to a radio base station farther than before the control. It is possible to provide a radio base station and a radio communication system that reduce degradation of communication quality for radio terminals.

  Hereinafter, embodiments of a radio base station according to the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 shows a basic configuration of a radio communication system to which a radio base station according to a first embodiment of the present invention is applied. A connection point 101 with an external network, radio base stations 111 and 112 fixedly installed, A mobile wireless terminal 121, 122, 123, 124 connected to the wired transmission path 102, the wireless base station 111 or the wireless base station 112 for connecting the base stations 111, 112 to each other and connecting to the external network via the connection point 101. It is composed of The cover area 131 is the range where the beacon signal of the radio base station 111 reaches, that is, the range where the mobile radio terminal can communicate with the radio base station 111, and the cover area 132 is the range where the beacon signal of the radio base station 112 reaches, ie, the mobile radio terminal Indicates a range in which communication with the radio base station 112 is possible. The boundary line 200 compares the strength of the beacon signal received by the mobile radio terminal and indicates the boundary to which connection to which radio base station is selected, and the mobile radio terminal located on the left side of the boundary line 200 Is connected to the radio base station 111, and the mobile radio terminal located on the right side is connected to the radio base station 112.

  For example, if the wireless communication system is a wireless LAN, the connection point 101 is connected to the Internet network, and if it is a local mobile phone network, it is connected to a nationwide public mobile phone network.

  In the initial state in FIG. 1, since the mobile radio terminal 121 is on the left side of the boundary line 200, it is connected to the radio base station 111, while the mobile radio terminals 122, 123, and 124 are on the right side of the boundary line 200. 112 is connected. That is, one mobile radio terminal is connected to the radio base station 111, and three mobile radio terminals are connected to the radio base station 112. Here, the radio base station 112 determines that it is desirable to reduce the beacon signal strength of the local station in order to approach the average value of two connected terminals, and performs the strength reduction.

  The cover area of the radio base station 112 after the radio base station 112 reduces the transmission power of the beacon signal is displayed as the cover area 133. In this situation, the boundary line 201 which is a new boundary line moves in a direction closer to the radio base station 112 than the original boundary line 200.

  As a result, the mobile radio terminal 124 that has been connected to the radio base station 112 until then is on the left side of the new boundary line 201, and is thus reconnected to the radio base station 111. As a result, both the wireless base stations 111 and 112 are connected to two terminals, and the number of connected terminals is averaged.

  Incidentally, at this time, since the mobile radio terminal 124 is inside the cover area 131, it can receive a beacon signal from the radio base station 111, but from the radio base station 111 as originally appropriate to connect to the radio base station 112. Therefore, the radio wave from the radio base station 111 is greatly attenuated, and as a result, the radio signal quality is expected to deteriorate. Specifically, transmission errors increase due to a low signal-to-noise ratio (CN ratio).

  Therefore, in the present invention, a radio base station (radio base station 111 in this drawing) that is connected to a distant mobile radio terminal for averaging the number of connected terminals reduces the transmission error by reducing the radio transmission speed. I try to prevent the increase. As is well known, in a radio signal subjected to digital modulation, if the transmission power is the same, the radio power density per unit frequency band increases as the frequency bandwidth to be transmitted becomes narrower, so that the CN ratio is improved, resulting in a transmission error rate. Can be reduced.

  In order to average the number of mobile radio terminals connected as described above, a radio base station that wants to reduce the number of mobile radio terminals lowers the beacon signal transmission power, and as a result, a radio to which a distant mobile radio terminal is newly connected. The base station can maintain communication quality by lowering the transmission rate. As a result, the mobile radio terminal connected to the radio base station 111 is used with its original speed performance reduced, but the speed due to bandwidth sharing caused by the large number of connected terminals without performing this power / speed control. The decrease in speed caused by the decrease and the increase in delay time due to access contention usually appears as a noticeable performance decrease.

  Next, the operation of the present embodiment shown in FIG. 1 will be described with reference to FIG. The horizontal axis indicates the position of the mobile radio terminal, and the vertical axis indicates the received signal strength at that position. First, in an initial state, a radio signal (beacon signal and data signal) of the radio base station 111 installed at the position a is represented by a signal curve 301, and a radio signal (beacon signal and data) of the radio base station 112 installed at the position b. Signal) is represented by a signal curve 302. At this time, the boundary line 200 is located at a position c which is substantially the center of both radio base stations.

  The mobile radio terminal 124 is located at the position d, and the level X, which is the reception intensity of the beacon signal from the radio base station 111, is compared with the level X, which is the reception intensity of the beacon signal from the radio base station 112. Therefore, the mobile radio terminal 124 selects and connects to the radio base station 112. Thereafter, reception of the beacon signal and the data signal is continued at level X.

  Thereafter, the wireless base station 112 reduces the transmission power of the beacon signal in order to average the number of connected terminals described above, and the beacon signal at that time is represented by a signal curve 303 (the data signal of the wireless base station 112 is a signal Curve 302 may remain). At this time, the boundary line 201 of both radio base stations moves to a position e where the signal curve 301 and the signal curve 303 intersect. Then, the mobile radio terminal 124 at the position d compares the level Y from the radio base station 111 with the level Z from the radio base station 112, and the level Y is larger, so the connection is switched to the radio base station 111. . For this reason, the communication which has been operated with the data signal of level X from the radio base station 112 until now is changed to the data signal of level Y from the radio base station 111, and the signal strength is lowered. As a result, the error rate of the demodulated data signal is increased.

  In order to prevent this increase in error rate, the radio base station 111 that increases the connection distance with the mobile radio terminal maintains the signal curve 301 and reduces the transmission rate of radio data to prevent the CN ratio from deteriorating. . Of course, since the mobile radio terminal connected to the radio base station 111 can know the transmission speed from the information included in the beacon signal, an operation to increase the reception CN ratio by narrowing the frequency bandwidth of the necessary reception signal is performed. .

  According to the above method, the operation of averaging the number of connected terminals is realized only by the function of the radio base station, and the mobile radio terminal side only needs to execute the conventional radio base station selection algorithm. In other words, there is no need to add any circuit or software to the mobile radio terminal, and there is no need to change the communication protocol between the radio base station and the mobile radio terminal, so there is no cost burden and the mobile radio currently in use This has a great advantage that the terminal can be used as it is.

  Several methods can be considered for determining whether to reduce the power of the beacon signal in order to reduce the number of connected terminals. The simplest method is to give a threshold to the number of connected terminals in advance. For example, if a threshold value of 10 is set, each radio base station constantly monitors the number of mobile radio terminals connected to the own station, and if it exceeds 10, the power of the beacon signal may be reduced. Since the number of connected terminals is less than 10 immediately after the beacon power is lowered, the so-called oscillation operation state is maintained as it is. Therefore, it goes without saying that the threshold value has hysteresis. For example, after the beacon power is lowered, the threshold value is lowered to 5 units, and operation is performed so as not to restore the power of the beacon signal until the threshold value is lowered. On the other hand, the radio base station in the adjacent cover area knows that the adjacent radio base station has performed the beacon power reduction operation, and performs the operation of reducing the radio transmission rate.

FIG. 3 shows a flow when the above judgment operation is realized by actual software. In the drawing, the numerical value n is the number of mobile radio terminals connected to the radio base station own station, N ₁ is a threshold for resetting the number of mobile radio terminals connected, which is determined to restore the transmission power of the beacon signal once reduced, N ₂ Is a threshold value for lowering the number of connected mobile wireless terminals, which is a decision to reduce the transmission power of the beacon signal.

  First, a beacon power standard value setting / radio speed standard value setting step 402 is executed from the operation start step 401 through a path 501. In the wireless communication system of the present embodiment, the standard values of beacon power and wireless speed are set to the maximum values of the standards for the purpose of exhibiting the best performance within the standards. Based on this, the radio base station transmits a beacon signal.

  Next, through the path 502, the local station connected terminal number detection step 403 is executed. As a result, it is known that there are n units (n is a natural number).

The number comparison step 404 is executed via the pass 503. This is for the purpose of returning the beacon power to the standard value in response to a decrease in the number of connected terminals by the radio base station once having lowered the beacon power. Comparing the threshold number N ₁ and n for restoration judgment. n is chosen as it is the path 506 is greater than the threshold N _1, so meets if smaller return condition to the contrary, through a path 504, to perform the beacon power standard values return step 405. Thereafter, the path 505 joins the path 506.

  Next, an adjacent radio base station data reading step 406 is executed. The wireless base stations are connected by wire as described above, and can transmit / receive information to / from each other. Since the local station knows in advance the adjacent wireless base station that partially overlaps its own coverage area, it selects and reads the necessary communication status data of the adjacent wireless base station from the data flowing on the wired transmission path 102. be able to.

  After this, a determination step 407 for determining whether or not there is a station in operation with the beacon power already reduced among the adjacent wireless base stations via the path 507 is executed. If there is a radio base station that is operating with beacon power reduction, the coverage area of the own station is substantially widened. Then, the next judgment cycle is entered.

  On the other hand, if there is no corresponding adjacent radio base station, the radio speed standard return step 409 is executed via the path 510. This is a step for returning the wireless speed to the standard once the wireless communication speed is lowered and then the neighboring wireless base station returns the beacon power to the standard so that it is no longer necessary to reduce the wireless communication speed of the local station. It is.

Next, the number comparison step 410 is executed via the path 511. The connection terminal number threshold N ₂ for determining the beacon power reduction is compared with the current connection terminal number n, and if it exceeds N ₂ , the beacon power reduction setting step 411 is performed via the path 513 in order to reduce the number of connection terminals. Execute. After this, the path 514 is joined to the path 502, and the next determination cycle is entered.

On the other hand, since if it is less than the threshold value N ₂ beacon power good remains the standard, joins the path 502 via path 512, enter the next determination cycle.

  Although the functions of the present application are realized by the above processing flow, the order of steps and the installation of paths are not limited to this.

The fixing the threshold number as described above requires only a small burden on the processing software although, in the case where the number of mobile radio terminal has increased as a whole communication system, exceeds a threshold value N ₂ for determining a number of radio base stations Therefore, there is a possibility that appropriate control cannot be performed for a radio base station having a remarkably large number of connected terminals, which originally has to reduce the number of connected terminals preferentially.

In order to operate rationally even in such a situation, know the number of mobile radio terminals included in the entire communication system and the average number of terminals per radio base station from the information on the number of connected terminals shared with each other, and power control based on that It is desirable to make this judgment. For example as the threshold value N ₂ of the above, the average number of terminals per base station in each case, it is conceivable to set the example 2 times the value. Alternatively, it is also effective to perform beacon signal control for a predetermined number of radio base stations in order of increasing number of connected terminals.

  In addition, the power control of the beacon signal and the control of the wireless transmission speed do not need to be a high and low two-step control, and three or more kinds of fine control are performed based on the connection terminal information of each wireless base station and the power information of the beacon signal. This makes it possible to achieve optimal control of the number of connected terminals and the transmission rate.

  Furthermore, when the communication at the mobile wireless terminal is a real-time video and audio signal, communication can be performed without any problems by switching the radio transmission speed switching control and the video and audio encoding / combining method and speed in conjunction with each other. Can continue. In general, devices that communicate video and audio via wireless or the Internet have a built-in mechanism for selecting the encoding / decoding speed according to the quality and capacity of the transmission path. It can be said that there is no particular difficulty. For example, videos of several tens of kbps to several hundreds of kbps are widely used, and voices of several kbps to several tens of kbps are widely used.

(Second Embodiment)
In the first embodiment, the radio base station 112 in FIG. 1 lowers the beacon signal strength of its own station in order to approach the average value of two connected terminals. As a result, the radio base station 111 that has connected to a distant mobile radio terminal for the purpose of averaging the number of connected terminals prevents an increase in transmission errors by lowering the radio transmission speed.

  On the other hand, in the present embodiment, the radio base station 111 increases the beacon signal strength of its own station in order to approach the average value of two connected terminals. As a result, the radio base station 111 that has connected to a distant mobile radio terminal in order to average the number of connected terminals reduces the radio transmission rate. In this way, since the radio base station that changes the beacon signal strength is the same as the radio base station that changes the radio transmission speed, a threshold value for the number of connected units whose beacon signal strength is changed is set in advance in each radio base station. It is not necessary to share beacon signal strength change information between wireless base stations, and a simpler wireless communication system can be constructed.

  The basic operation principle itself of this embodiment is the same as that described in FIG. Here, an actual operation flow of the radio communication system in the present embodiment will be described with reference to FIG.

In the drawing, the numerical value n is the number of mobile radio terminals connected to the radio base station itself, N ₃ is a threshold value for determining the beacon signal transmission power, and N ₄ is a determination to return the beacon signal transmission power to the standard value. It is a terminal numerical value threshold value used as a reference.

  First, a beacon power standard value setting / radio speed standard value setting step 602 is executed from the operation start step 601 through a path 701. In the wireless communication system of this embodiment, in order to increase the beacon power and control the number of connected terminals, the standard value of the beacon power is set lower than the maximum value that can be transmitted. Based on this, the radio base station transmits a beacon signal.

  Next, through the path 702, the local station connected terminal number detection step 603 is executed. As a result, it is known that there are n units (n is a natural number).

The number comparison step 604 is executed via the path 703. This is intended to increase the beacon power when the number of connected terminals is less than the threshold. Compare and the n threshold number N ₃ for power increase judgment. n is chosen as it is the path 706 is greater than the threshold value N _3, since qualify for power increase smaller Conversely, via path 704, to perform the beacon power increase setting step 605. In this case, since the radio base station is connected to a distant mobile radio terminal in order to average the number of connected terminals, it is necessary to reduce the radio speed in order to maintain communication quality. For this reason, after executing the beacon power increase setting step 605, it passes through the path 705 and joins the path 702 via the wireless speed decrease setting step 606.

If the path 706 is selected in the number comparison step 604, the next number comparison step 607 is executed. Comparing the current connection terminal count n and the connecting terminal count threshold N ₄ for determining whether or not to return the beacon power to a standard value, in order to reduce the number of connection terminals, if exceeded N _4, path After step 707, step 608 is executed to restore the beacon power to the standard value and the radio speed to the standard value. After that, the path 708 is joined to the path 702, and the next determination cycle is entered.

On the other hand, since it if the beacon power does not need to be changed less than the threshold value N _4, joins the path 702 via path 709, enter the next determination cycle.

  As described above, in the second embodiment, the standard value of the beacon power is suppressed to be lower than the maximum transmittable power, so that the connection of the radio base station can be performed with a simpler procedure than in the first embodiment. It is possible to average the number of terminals. Furthermore, since there is no need to share beacon power change information between wireless base stations, a simpler wireless communication system can be configured.

(Third embodiment)
FIG. 5 shows a basic configuration of a radio communication system to which a radio base station according to the third embodiment of the present invention is applied. A connection point 101 with an external network, radio base stations 111, 112, 113 fixedly installed. , 114, a server device 140 wired to the wireless base stations 111 to 114, a wired transmission path 102 that connects the wireless base stations 111 to 114 and the server device 140 to each other and connects to an external network via the connection point 101, And a large number of mobile radio terminals (not shown) that are wirelessly connected to any one of the radio base stations 111 to 114.

  When a large number of wireless base stations are two-dimensionally arranged as shown in FIG. 5 and the respective cover areas (cover areas 131 to 134 in FIG. 5) are complicatedly overlapped, the wireless base stations share information with each other. It takes a very large processing load to exchange and determine the optimum beacon signal transmission power and wireless transmission speed of the local station. Further, when the control algorithm is improved, software must be updated for each individual radio base station, and the load on the operation side of the radio communication system is large.

  Therefore, with the configuration of FIG. 5, each wireless base station simply sends the communication status of its own station, that is, the number of connected terminals and the transmission power of the beacon signal to the server device 140 in a wired manner. By grasping it, it is possible to send a control signal back to each radio base station. As a result, each radio base station has only to passively set the transmission power and radio transmission speed of the beacon signal based on the control signal from the server device 140, and the above control algorithm can be improved only by the server device 140. It becomes a system with excellent operability.

  As described above, according to the present invention, the beacon transmission power of a radio base station can be obtained even in a situation where the number of connected radio terminals of a plurality of radio base stations is uneven and the communication load varies depending on the radio base station. By controlling the wireless transmission rate, it is possible to average the communication load of the wireless communication system and maintain the communication quality.

  In all the embodiments described above, the mobile radio terminals that reduce the radio transmission speed have been described as all mobile radio terminals connected to the target radio base station. However, the present invention is not limited to this. For example, the radio transmission rate of only the newly connected mobile radio terminal may be reduced by controlling the beacon transmission power.

  According to the present invention, when the number of mobile radio terminals connected to a specific radio base station among a plurality of radio base stations is significantly increased in a radio communication system, the number of connections is decreased, and the influence of a long distance is increased. It is intended to prevent deterioration in communication quality of a mobile radio terminal that is to communicate with a radio base station, and is widely used in a very general radio communication system including a plurality of radio base stations and mobile radio terminals. Is possible.

The figure which shows the basic composition of the radio | wireless communications system in the 1st Embodiment of this invention. The figure showing the change of the signal strength by the electric power control of the beacon signal in the 1st Embodiment of this invention The figure which shows the judgment procedure of the electric power intensity of a beacon signal and radio | wireless transmission rate control in the 1st Embodiment of this invention The figure which shows the judgment procedure of the power intensity of a beacon signal and radio | wireless transmission rate control in the 2nd Embodiment of this invention. The figure which shows the structure of the radio | wireless communications system in the 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Connection point (with external network) 102 Wired transmission line 111-114 Wireless base station 121-124 Mobile wireless terminal 131-134 Cover area 140 Server apparatus 200,201 Boundary line 301-303 (Receiving of radio base station selection) Signal curve

Claims (8)

In a wireless communication system having a plurality of wireless base stations and a plurality of mobile wireless terminals that wirelessly communicate with any of the wireless base stations, the mobile wireless terminal uses received power of a beacon signal transmitted by the plurality of wireless base stations. When functioning to select a wireless base station to be connected by comparing, the wireless base station, according to the number of mobile wireless terminals connected to its own station, the transmission power of the beacon signal emitted from its own station, A radio base station that controls a radio transmission speed with a mobile radio terminal to be connected. When the number of mobile wireless terminals connected to the wireless base station is less than a predetermined threshold, the wireless base station increases the transmission power of a beacon signal emitted from the mobile station and communicates with the mobile wireless terminal connected to the mobile station. The radio base station according to claim 1, wherein the radio base station is controlled to reduce a radio transmission rate. Information on the wireless communication status of each wireless base station is shared by mutual communication, and using this shared information, the transmission power of the beacon signal emitted from the own station, the wireless transmission speed of the mobile wireless terminal connected to the own station, and The radio base station according to claim 1, wherein the radio base station is controlled. The radio base station according to claim 3, wherein the information on the radio communication status of the radio base station includes information on the number of mobile radio terminals connected to each radio base station and power information of a beacon signal. Control to reduce at least the beacon signal transmission power for radio base stations that reduce the number of mobile radio terminals to be connected, and at least mobile radio to radio base stations to increase the number of mobile radio terminals to be connected The radio base station according to claim 4, wherein control is performed so as to reduce a radio transmission rate with the terminal. A plurality of wireless base stations; a plurality of mobile wireless terminals that wirelessly communicate with any of the wireless base stations; and a server device that is wired to the plurality of wireless base stations. When the server device functions to select the radio base station to be connected by comparing the received power of the beacon signal to be transmitted, the server device obtains the number information of the mobile radio terminals currently connected to each of the radio base stations. A signal for controlling the transmission power of the beacon signal in each of the plurality of radio base stations and the radio transmission speed with the mobile radio terminal based on the number information thereof, and generating the control signal for each radio base station A wireless communication system, wherein The control signal is controlled to reduce the transmission power of at least a beacon signal for a radio base station that reduces the number of connected mobile radio terminals, and for a radio base station that increases the number of connected mobile radio terminals 7. The radio communication system according to claim 6, wherein the radio communication system is a control signal for controlling at least a radio transmission rate with a mobile radio terminal. The control signal is a control signal for controlling a radio base station that increases the number of mobile radio terminals to be connected to increase at least the transmission power of the beacon signal and reduce the radio transmission speed with the mobile radio terminal. The wireless communication system according to claim 6.

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