JP5906438B2 - Communications system - Google Patents

Description

  The present invention relates to a communication system.

  In a conventional communication system (for example, PBX (Private Branch eXchange) wireless system), a communication terminal sequentially switches base stations to be communicated among a plurality of base station apparatuses (hereinafter also simply referred to as “base stations”). Can move. Such switching of base stations is called handover. In order for a communication terminal that communicates with a base station using a time-division wireless communication scheme (for example, TDMA / TDD) to suitably perform handover between the plurality of base stations, the plurality of base stations transmit / receive timing to / from each other. Need to be synchronized.

  The following methods are known as a method of synchronizing a plurality of base stations. A time information server transmits time information to a plurality of base stations via a LAN (Local Area Network). And each base station adjusts the clock generator in an own apparatus based on the reception time of time information, and time information (for example, refer patent document 1).

  The following method is also known. A master-slave relationship (synchronization tree) is constructed as a master that generates transmission timing and reception timing and a slave that synchronizes according to the master among a plurality of base stations, and one base station is set as the highest master of the layer. Other base stations operate as slaves according to higher-layer base stations, receive a synchronization signal transmitted by the master base station by radio, and set their own transmission timing and reception timing. Then, the slave base station corrects a difference in transmission timing and reception timing with the master base station of the synchronization partner at a predetermined time interval (see, for example, Patent Document 2).

  The following method is also known. Japanese Patent Application Laid-Open No. 2004-228561 discloses an apparatus that organizes an ad hoc network from a set of a plurality of nodes and automatically selects a central coordinator node. This creates a topology map that describes the number and quality of communication links between nodes for all nodes, selects the best candidate node from this map information, and creates a high-quality bidirectional communication link between nodes. It seeks to achieve a possible and efficient network. (See Patent Document 3).

Japanese translation of PCT publication No. 2003-509973 JP 2002-165269 A JP 2006-50636 A

  In such a system, each base station normally receives a synchronization signal periodically issued by the master base station in order to synchronize with an upper master base station. When each base station loses sight of the synchronization signal, the synchronization with other base stations is shifted. As a result, each base station may not be able to synchronize with other base stations with accuracy other than restarting.

  In the technique of Patent Document 1, when the clock function of the time information server is stopped, a plurality of base stations cannot synchronize with each other with high accuracy. In the technique of Patent Document 2, when the timing generation function of the reference station is stopped, a plurality of base stations cannot be synchronized with each other with high accuracy.

  When building an IP-based in-house public wireless system, the wired NW (Network) between the base station (corresponding to a cordless master unit) and the PBX (main device) is IP-based, so the timing information is transmitted to the wired NW. It cannot be used for. Therefore, the system timing is synchronized by wireless synchronization (air synchronization).

  Since the hosted service cannot design a wireless system using an advanced server, it is necessary for each base station to design a timing master and a synchronization tree only with each other's radio wave condition and electric field strength. However, in a complex radio wave environment in a building, it is difficult to design an accurate tree manually, and after installation, communication between base stations fails, and some base stations operate out of sync. There was a stop.

  Patent Document 3 states that an efficient network can be realized by analyzing a topology map, but forming an efficient tree structure for synchronization in a time-division wireless communication system base station. It does not suggest.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a communication system that can form a more stable tree configuration and reduce the burden on an installation worker.

  The communication system of the present invention is a communication system in which a plurality of base station apparatuses communicate by a time division wireless communication method, each base station apparatus measures the received electric field strength of a signal of another base station apparatus that can be received, Reception when any two base station apparatuses capable of communication are connected by a route through which at least one other base station apparatus is interposed, and when they are directly connected without interposing another base station apparatus A base station that compares the electric field strength to determine a route between the two base station devices and has the smallest maximum number of intervening base station devices in the route between other base station devices that can communicate with each other. Determine the device as the highest master.

  According to this configuration, each base station apparatus can measure the received electric field strength of signals of other base station apparatuses that can be received, and can determine the highest master based on the measurement result of the received electric field intensity. Therefore, the installation operator can form a more stable tree structure without sequentially checking the communication environment, and the burden on the operator can be reduced.

  According to the present invention, the installation worker can form a more stable tree structure without sequentially checking the communication environment, and the burden on the worker can be reduced.

The block diagram which shows the structural example of the communication system in embodiment of this invention. The block diagram which shows the structural example of the base station apparatus in embodiment of this invention The figure which shows the example of the time division system in the radio | wireless communication in embodiment of this invention The figure which shows an example of the transmission / reception timing of the synchronous signal in the normal state of the base station apparatus in embodiment of this invention The figure which shows the example of correction | amendment of the communication timing in the normal state of the base station apparatus in embodiment of this invention The figure which shows an example of the correspondence of the received electric field strength and Cost value of the base station apparatus in embodiment of this invention (A), (b) is a figure which shows the criteria for determining the master / slave relationship of several base station apparatuses in embodiment of this invention. The figure for demonstrating the image which measures received electric field strength between several base station apparatuses in embodiment of this invention The flowchart which shows the survey process for determining the master of the highest layer of a base station apparatus in embodiment of this invention The flowchart which shows the Cost value calculation process between several base station apparatuses in the survey process in embodiment of this invention The flowchart which shows the bottleneck calculation process for discriminating the base station apparatus used as a bottleneck in the survey process in embodiment of this invention The figure showing an example of the communication area at the time of determining a certain base station apparatus as the master of the highest layer in the embodiment of the present invention The figure showing an example of the tree structure at the time of determining a certain base station apparatus as the master of the highest layer in the embodiment of the present invention The figure showing an example of the communication area at the time of deciding another base station apparatus as the master of the highest layer in the embodiment of the present invention The figure showing an example of the tree structure at the time of deciding another base station apparatus as the master of the highest layer in the embodiment of the present invention The figure showing an example of the communication area at the time of installing the base station apparatus in embodiment of this invention across a floor in a building The figure showing the example of the communication path at the time of installing the base station apparatus in embodiment of this invention in wide facilities, such as a hotel

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram illustrating a configuration example of a communication system 1000 according to an embodiment of the present invention. The communication system 1000 includes a base station apparatus (CS: Cell Station) 100, a communication terminal (PS: Personal Station) 200, and a SIP (Session Ini).
tiation Protocol) server 300, telephone 400, and router 500.

  A plurality of CSs 100 exist hierarchically in the communication system 1000. In FIG. 1, a plurality of CSs 100 are referred to as CS100M, CS100M1, and CS100M2. In FIG. 1, CS 100M is arranged in the highest layer and is, for example, a device (Timing master CS) serving as a reference for synchronization. CS 100M1 and CS 100M2 are devices (Slave CS) that are arranged in a lower layer of CS 100M and operate according to the synchronization standard of CS 100M. CS100M1 and CS100M2 may also be arranged hierarchically. For example, the CS 100M1 is arranged in an upper layer of the CS 100M2.

  PS 200 is a mobile communication terminal that operates as a slave unit and is movable. The PS 200 is, for example, a mobile phone, a personal digital assistant (PDA), or a portable sensor device. The PS 200 acquires location information using, for example, the GPS function of the PS 200, and performs handover with the CS 100 based on the acquired location information.

  The SIP server 300 uses the SIP protocol, for example, associates a telephone number with an IP address, and executes a call control process for calling and connecting a communication partner.

  The telephone 400 is, for example, an extension telephone, and communicates with another telephone device (for example, PS 200) via the SIP server 300, for example.

  The router 500 connects the communication system 1000 and the external network 600 and relays data in the communication system 1000 and data in the external network 600.

  The personal computer (PC) 700 is provided with setting work software, functions to support the CS installation work by the worker, and to activate a survey operation for determining a master base station (master CS) described later. The setting work software is one of programs, and is stored in a memory (not shown) of the PC 700, for example. Various functions are realized by the CPU (not shown) of the PC 700 executing the setting work software program.

  The router 500 is connected to the CS 100, PS 200, SIP server 300, telephone 400, and PC 700 via a wired network N1 (for example, an IP network).

  Next, a configuration example of the CS 100 will be described. FIG. 2 is a block diagram illustrating a configuration example of the CS 100. The CS 100 includes a wireless communication unit 101, an antenna unit 102, a wired communication unit 103, a wireless communication determination unit 104, a clock generation unit 105, a communication timing determination unit 106, a communication timing correction unit 107, a synchronization state determination unit 108, a storage unit 109, A learning processing unit 110 and a control unit 111 are provided.

  The wireless communication unit 101 communicates with other communication devices via the antenna unit 102 and the wireless network. The wireless network is a wireless communication network based on, for example, DECT (Digital Enhanced Cordless Communication).

  The wired communication unit 103 communicates with other communication devices via a wired network. The wired network is, for example, a wired LAN, a wired WAN, or a power line.

The wireless communication determination unit 104 determines whether the wireless communication unit 101 has normally received the synchronization signal from the master CS. The wireless communication determination unit 104 determines whether or not the CS wireless communication unit 101 has received the synchronization signal from the master CS at a predetermined reception timing. For example, when the synchronization signal is missed, there is a case where radio interference occurs at the reception timing of the synchronization signal when the power of the other CS that transmits the synchronization signal to the CS is off. Note that the master CS is a CS serving as a reference for synchronization of each CS, and may be a CS other than the CS 100M.

  The clock generation unit 105 operates each unit in the CS and generates a reference clock for determining the communication timing of the wireless communication unit 101.

  The communication timing determination unit 106 determines the communication timing of the communication signal by the wireless communication unit 101 based on the reference clock of the clock generation unit 105. The communication signal includes a synchronization signal for synchronizing with another CS.

  When the communication timing correction unit 107 loses sight of the synchronization signal from the master CS, the communication timing correction unit 107 corrects the communication timing for the wireless communication unit 101 to communicate based on the synchronization signal acquired from another CS via a wired network, for example. To do. The communication timing includes at least one of transmission timing and reception timing by the wireless communication unit 101.

  The control unit 111 controls each unit in the CS so as to perform a survey operation described later in cooperation with another CS.

  By executing the setting work software, the PC 700 determines one CS among a plurality of CSs as a temporary master CS and sends an activation instruction to the CS. Upon receiving the activation instruction, the CS control unit 111 performs a survey operation.

  In the example of the tree configuration illustrated in FIG. 13, radio synchronization of a certain CS (for example, CS (2)) is synchronized according to a synchronization signal from a master CS (for example, CS (1)) arranged in an upper layer. CS (7), which is lower than CS (2), is synchronized according to a synchronization signal from CS (2) as a master. The other CSs are synchronized according to the synchronization signal from the upper master CS.

  Here, the CS identification code is written in parentheses like CS (1), but in the drawing, the CS identification code is surrounded by a circle (circle). In the drawings, each CS may be represented by omitting the character “CS” and surrounding the identification code with a circle.

  The communication timing correction unit 107 of each CS corrects the communication timing according to the synchronization signal from the CS arranged in the upper layer. When correcting the communication timing, the reference clock of CS 100 may be corrected by a clock correction unit (not shown).

  The storage unit 109 illustrated in FIG. 2 includes, for example, a ROM (Read Only Memory) or a RAM (Random Access Memory), and stores various types of information. For example, the storage unit 109 stores information on the master CS to be synchronized, information on CS candidates that can be a determination request destination of the synchronization state when the synchronization is lost.

  The storage unit 109 stores information on at least one of transmission channels and slots of synchronization signals of other CSs in the network, or information on scheduled reception timing. The information on the transmission channel and transmission slot of the synchronization signal is an example of information on the time position where the synchronization signal is transmitted. In addition, the storage unit 109 stores, for example, information on time lag or correction parameter information obtained by learning processing.

  The learning processing unit 110 determines the correction parameter for correcting the communication timing according to the learning result while sequentially learning the time lag between the own CS and the other CS in the asynchronous state. Therefore, the learning processing unit 110 has a function as a correction parameter determination unit. This correction parameter is used in a state of being lost.

  The wireless communication determination unit 104, the communication timing determination unit 106, the communication timing correction unit 107, the synchronization state determination unit 108, and the learning processing unit 110 realize each function by executing a program stored in the storage unit 109. To do.

  Next, a configuration example of a communication frame in wireless communication will be described. In wireless communication in the communication system 1000, for example, as shown in FIG. 3, a time division method is used in which communication is performed with 10 msec as one frame and one frame divided into 24 slots. The time-division communication includes, for example, TDMA / TDD (Time Dimension Multiple Access / Time Division Duplex) communication. In the example shown in FIG. 3, a time length obtained by dividing one frame (10 msec) into 24 equal parts is defined as one slot. Each communication device is assigned one of the slots each time communication is started. Each communication device communicates with other communication devices using the assigned slot.

  The synchronization signal is also called a beacon signal and includes synchronization data (for example, Syncword). Syncword is a predetermined numeric string for timing synchronization, and is data of a known pattern determined in advance, which is synchronization information for synchronizing the above-described telephone device (PS200) and other slave CSs. In the DECT method, a unique Syncword is assigned to each network, and the Syncword is commonly included in signals transmitted from terminals belonging to one network.

  Next, synchronization processing in the normal state of the CS 100 will be described. FIG. 4 is a diagram illustrating an example of the transmission / reception timing of the synchronization signal in the normal state of the CS 100. FIG. 5 is a diagram illustrating an example of correcting the communication timing in the normal state of the CS 100.

  Usually, the CSs are synchronized with each other by periodically receiving a synchronization signal from the master CS. 4 and 5 exemplify synchronization processing among CS 100M, CS 100M1, and CS 100M2. The CS 100M operates as a synchronization master (master CS) of the CS 100M1, and the CS 100M1 operates as a synchronization master of the CS 100M2.

  As shown in FIG. 4, CS 100M transmits a synchronization signal at a constant interval (for example, slot 0 of communication signal 30) (synchronization signal TX). As shown in the figure, the slave CS100M1 receives the synchronization signal from the master CS100M (RX) and operates in synchronization with the communication timing of the CS100M. In addition, CS 100M1 transmits its own synchronization signal (synchronization signal TX) at a constant interval (for example, slot 7 of communication signal 30).

  The CS 100M2 illustrated in FIG. 4 receives the synchronization signal from the CS 100M1 (RX), and operates in synchronization with the communication timing of the CS 100M1. In addition, CS 100M2 transmits its own synchronization signal at regular intervals (for example, slot 15 of communication signal 30).

  As shown in FIG. 5, when a time lag occurs between CS 100M1 and CS 100M, CS 100M 1 detects the time position of Syncword included in the synchronization signal, and corrects the communication timing using the detection result. . FIG. 5 illustrates a case where the communication timing of the CS 100M1 is delayed from a predetermined timing.

  In addition, when a time lag occurs between CS 100M2 and CS 100M1, CS 100M2 corrects the communication timing using the information on the time lag included in the synchronization signal. FIG. 5 illustrates a case where the communication timing of CS100M2 is advanced from a predetermined timing.

  Next, a survey operation for determining the highest master base station (master CS) when the base station apparatus (CS 100) is installed in a building or the like will be described.

  FIG. 6 shows that when the base station apparatus receives a signal from another base station apparatus, the field strength (RSSI: Received Signal Strength Indicator) values are divided into a plurality of sections, and the weighted parameters according to the respective field strength sections An example is given. Hereinafter, a parameter set for each RSSI section is referred to as Cost (Cost value).

  For example, when a radio communication unit 101 of a certain CS 100M receives a signal from another CS 100M1, the cost value is “1” if the electric field strength is −40 dBm or higher, and the cost value is −50 dBm to −40 dBm. Set to “2”. The Cost value is weighted so as to increase as the electric field strength decreases.

  FIGS. 7A and 7B show basic determination criteria for determining the master / slave relationship of a plurality of base station apparatuses (CS100). The Cost value when CS (1) receives a signal from CS (2) is “Cost (2)-(1)”, and the Cost value when CS (2) receives a signal from CS (4). Is “Cost (4)-(2)” and CS (1) directly receives the signal from CS (4), the cost value is “Cost (4)-(1)”. The determination is made according to the following criteria (a) and criteria (b).

  In the criterion (a), when Cost (4)-(1) is larger than the sum of Cost (2)-(1) and Cost (4)-(2), CS (1) and CS ( 4), another CS (CS (2) in FIG. 7) is interposed, and CS (4) is a slave of CS (2). In this case, it is conceivable that C (1) and CS (4) are considerably far from each other, or that an obstacle exists between C (1) and CS (4). Therefore, it is better to interpose another CS between C (1) and CS (4).

  Further, in the criterion (b), when Cost (4)-(1) is smaller than the sum of Cost (2)-(1) and Cost (4)-(2), CS (1) and CS (4) is a slave of CS (1) without interposing another CS with CS (4). In this case, it is considered that CS (1) and CS (4) are relatively close in distance, and stable communication is possible. Therefore, it is better to connect CS (1) and CS (4) directly.

  Note that the case where Cost (4)-(1) is the same as the sum of Cost (2)-(1) and Cost (4)-(2) is handled in the same manner as the criterion (b). That is, no other CS is interposed between CS (1) and CS (4).

  In the survey process, all CSs sequentially receive signals from other CSs and calculate Cost based on the respective reception strengths. That is, each CS sequentially performs continuous reception operation, receives signals from all receivable CSs, extracts the ID information of the source CS, and measures the received field strength (RSSI) of the signals. And converted into a Cost value and recorded together with the ID information. The CS ID information is an example of CS identification information.

  FIG. 8 shows an image of measuring the received electric field strength with a plurality of CSs.

For example, the cost value is “2” between CS (1) and CS (2), and CS (2) and CS (2
The cost value is “1” with respect to 7). The ID information of the source CS of all signals received by each CS and the Cost value related to the signal are collected at one place via a wired network.

  Next, the survey process will be described in detail.

  FIG. 9 is a flowchart showing a survey process for determining the master CS of the highest layer, and is executed in the control unit 111 of each CS. One CS among the plurality of CSs is determined as a temporary master CS by the execution of the setting work software by the PC 700. By sending an activation instruction from the PC 700 to the temporary master CS, the CS that has received the activation instruction executes a survey process.

  In the CS installation work, first, a plurality of CSs (CS (1), CS (2),...) Are installed, and each is connected by a wired network. Further, the PC 700 that executes the setting work software is connected to the same wired network.

  When the PC 700 accepts an operation for starting survey processing by an operator through an operation unit (not shown), the temporary master CS is determined and an activation instruction is sent using a wired network. As shown in FIG. 9, when the temporary master CS is determined, the control unit 111 of the temporary master CS controls the wired communication unit 103 and notifies the other CSs of information on the temporary master CS via the wired network. (Step S1). As a result, the other CSs start operating in synchronism with the temporary master CS, and a temporary wireless tree is formed.

  After forming the temporary wireless tree, the control unit 111 of the temporary master CS controls the wired communication unit 103 to collect the Cost value for each CS and report it to the temporary master CS. Instruction is given via the wired network (step S2). The control units 111 of other CSs perform an operation of collecting Cost values according to instructions received via the wired network. As a result, all CSs including the temporary master CS start the cost value calculation process (step S3).

  FIG. 10 shows a Cost value calculation process between a plurality of base station apparatuses in the survey process.

  In the cost value calculation process, the control unit 111 of each CS controls the wireless communication unit 101, and sequentially starts a reception operation in accordance with an instruction sent from the temporary master CS via the wired network (step S21).

  For example, the control unit 111 of the provisional master CS selects a certain slave CS (for example, CS (2)), causes the slave CS to perform a continuous reception operation, and receives another CS (CS (3), CS (4). ,... Are transmitted (step S22). In the selected slave CS, in the continuous reception operation, the wireless communication unit 101 receives signals transmitted from other CSs and detects the received field strength (RSSI) of each signal.

  The control unit 111 of the selected slave CS associates the ID information of all other CSs that can receive the signal in the continuous reception operation with the Cost value determined based on the RSSI of the signal transmitted from the CS. Recording is performed (step S23). All other receivable CSs mean all CSs that can be received by the wireless communication unit 101 and whose ID information of the transmission source can be identified.

In step 24, the control unit 111 determines whether or not all CS detection operations have been completed. If there is an incomplete CS (step S24: No), the slave CS is updated (step S25), and RSSI detection is repeated.

  When all the CS detection operations are completed (step S24: Yes), in each CS, the wired communication unit 103 notifies the temporary master CS of the cost value via the wired network. That is, each CS associates the ID information of all other CSs that can be received with the Cost value related to the signal from the CS, and notifies the temporary master CS of the Cost value (step S26).

  In FIG. 9, when the cost value calculation process in step S3 is completed, the control unit 111 of the temporary master CS collects ID information and cost values of all other CSs that can be received by each CS. Then, the control unit 111 of the temporary master CS creates a map on which the Cost value between the CSs is placed (step S4).

  Then, the control unit 111 of the temporary master CS assumes that each CS is indirectly connected to one or more other CSs via a route through which one or more CSs are interposed. Based on the determination criteria shown in FIG. 7, the value obtained by adding the parameters between the base station devices in each route (one or more) is compared with the value of the parameters in the case of direct connection between the base station devices. Thus, the master / slave relationship is provisionally determined.

  Next, the control unit 111 of the provisional master CS, based on the provisional decision, determines the maximum number of stages on each route that is indirectly connected to the other CS for each CS, that is, other intervening intermediates. The maximum number of CSs (number of intervening nodes) is detected (step S5).

  For example, for CS (3), if there is only one CS (4) on the route from CS (3) to CS (5), the number of intervening nodes is “1”. Further, if there are two CS (2) and CS (6) on the route from CS (3) to CS (8), the number of intervening nodes is “2”. In the case of CS (3), if the number of intervening nodes “2” in the route from CS (3) to CS (8) is larger than the number of intervening nodes in other routes, “2” is the maximum for CS (3). It becomes the number of steps.

  Similarly, if two CSs (7) and CS (9) are present on the route from CS (2) to CS (10), the number of intervening nodes is “2”. Similarly, if four CSs are present on the route from CS (2) to CS (8), the number of intervening nodes is “4”.

  As described above, the control unit 111 of the provisional master CS checks the maximum number of stages (the number at which the number of intervening nodes is maximum) on each route indirectly connected to other CSs for each CS.

  In step S6, the control unit 111 of the temporary master CS determines whether or not the determination of the maximum number of stages has been completed for all CSs. If it is not completed (step S6: No), it is updated to another CS as a detection target (step S7), and the detection of the maximum number of stages in step 5 is repeated.

  When the operation for determining the maximum number of stages for all CSs is completed (step S6: Yes), in the next step, the control unit 111 determines the minimum number of stages among the number of stages (step S8).

In step S9, the control unit 111 of the temporary master CS determines whether there are a plurality of CSs having the same minimum number of steps (step S9). If there is only one CS having the minimum number of steps (step S9: No), in step S10, the control unit 111 of the temporary master CS assigns one CS having the minimum number of steps to the formal master CS of the highest layer. Determine as.

  When there are a plurality of CSs having the minimum number of stages (step S9: Yes), the control unit 111 of the temporary master CS counts the number of slave CSs whose hierarchy is positioned one level below (directly below) for each CS. The maximum number of CSs is obtained (step S11).

  In the next step 12, it is determined whether or not there are a plurality of CSs having the same maximum number of CSs one step lower (step S12). If there is not a plurality of CSs that are the same, that is, if there is only one CS having the maximum number of CSs one level lower (step S12: No), the control unit 111 of the temporary master CS sets the CS as the highest layer. Is determined as an official master CS (step S13).

  If there are a plurality of CSs having the maximum number of CSs one level lower (step S12: Yes), the process proceeds to the bottleneck calculation process (step S14). Hereinafter, each CS in the case where there are a plurality of CSs having the maximum number of CSs one level lower is set as a master CS candidate.

  FIG. 11 shows a bottleneck calculation process for determining a base station apparatus that becomes a bottleneck in the survey process. The operation in FIG. 11 is an operation by a master CS candidate.

  First, in step 31, the control unit 111 of the temporary master CS counts the total number (N) of subordinate CSs for each CS immediately below the master CS candidate.

  Next, the control unit 111 of the temporary master CS pays attention to one of the CSs directly under one master CS candidate (Step S32), and the CS under the target CS (Xth CS). It is determined whether the number of is larger than the number of CSs under the control of other CSs (step S34). The variable X is the serial number of the target CS, the variable B is a variable for storing the number of CSs under the CS, and the initial value is set to B = 0 (step S33).

  When the number of CSs under the target CS (Xth CS) is larger than the number of CSs under the control of other CSs (step S34: Yes), the control unit 111 of the temporary master CS The number of CS under the (Xth) subordinate is stored in variable B, and variable B is updated (step S35).

  Next, the control unit 111 of the temporary master CS updates the variable X (step S36) and pays attention to the next CS. If the number of CSs under the target CS (Xth CS) is smaller than or equal to the number of CSs under other CSs (step 34: No), the variable B is not updated. , Update variable X.

  In step 37, the control unit 111 of the temporary master CS determines whether or not the comparison operation of all CSs directly under one master CS candidate is completed (X> N?) (Step S37). If it is not completed (step 37: No), the process is repeated until the comparison is completed for all the CSs directly under the master CS candidate, and the process proceeds to step S34.

  When the comparison is completed for all the CSs directly under one master CS candidate (step 37: Yes), the process proceeds to step S38. The control unit 111 of the temporary master CS sets the value of the variable B of the CS having the maximum value of the variable B among the CSs directly under the master CS candidate as a parameter indicating the bottleneck of the master CS candidate. (Step 38).

In step 39, the control unit 111 of the temporary master CS determines whether or not the bottleneck calculation has been completed for all the master CS candidates (step S39). If it is not completed (step 39: No), the process is repeated until all the master CS candidates are completed, and the process proceeds to step S31. When the bottleneck calculation is completed for all the master CS candidates (step 39: Yes), the process in FIG. 11 is terminated and the process returns to the process in FIG.

  When the bottleneck calculation process is completed for all the master CS candidates, in FIG. 9, the control unit 111 of the temporary master CS determines the CS having the smallest parameter B representing the bottleneck as an official master (step S15). The parameter (variable) B means the size of the bottleneck under the CS.

For example, the master CS candidates are CS (2), CS (3), CS (7), and CS (2)
B1 = “2” for CS, B2 = “3” for CS (3), and B3 = “1” for CS (7). In this case, CS (3) having the smallest parameter B (B1, B2, B3) representing the bottleneck is determined as the formal master CS of the highest layer.

  By such determination, the master CS can be determined so that the bottleneck of each CS placed immediately below the highest layer is leveled. The leveling of the bottleneck is a state where the difference between superiority and inferiority is minimized.

  As described above, assuming that each master CS candidate is a master CS, the value of the variable B having the maximum value of the variable B among the CSs located immediately under each assumed master CS is determined for each master CS candidate. Extract. In this case, the bottleneck can be leveled most if the CS having the smallest value of the variable B among the master CS candidates is set as the formal master CS.

  When the formal master CS is determined as described above, the temporary master CS is notified by the wired communication unit 103 to the other CSs through the wired network and is notified of information such as an ID related to the master CS. To do. Thereby, a new radio tree is formed around the determined master CS. Thereafter, each CS operates according to a new radio tree.

  FIG. 12 shows an example of a communication area when a certain CS is determined as the master of the highest layer. FIG. 13 shows an example of a tree configuration when the same CS as in FIG. 12 is determined as the master of the highest layer.

  In the example of FIG. 12, CS (1) is the master of the highest layer, and a plurality of CSs operating as slaves are arranged under CS (1). For example, CS (2) that operates as a slave to CS (1) and CS (3) that operates as a slave to the same CS (1) are in total within the communication area of CS (1). Located in. In addition, in the communication area of CS (4), there are two, CS (5) that operates as a slave to CS (4) and CS (6) that operates as a slave to the same CS (4). To position. In addition, in the communication area of CS (7), there are two, CS (9) that operates as a slave to CS (7) and CS (11) that operates as a slave to the same CS (7). To position. In FIG. 12, as an example, the communication area is illustrated only for CS (1), CS (4), and CS (7) having a plurality of slave CSs under the control.

  Each CS synchronizes with the radio according to a master CS in a higher layer than each CS. For example, the CS (10) synchronizes according to the upper master CS (9). CS (9) synchronizes according to the upper master CS (7). CS (7) synchronizes according to the higher master CS (2). CS (2) synchronizes according to the highest master CS (1).

FIG. 14 shows an example of a communication area when another CS is determined as the master of the highest layer. FIG. 15 shows an example of a tree configuration when the same CS as in FIG. 14 is determined as the master of the highest layer. The example of FIGS. 14 and 15 is an example of a tree configuration set with emphasis on the bottleneck.

14 and 15, CS (7) is the master of the highest layer, and there are many CSs operating as slaves under CS (7). For example, CS (3), CS (4), CS (6), CS (9) and CS (11) existing in the communication area of CS (7) operate as slaves of CS (7). Also, CS (2) and CS (5) existing in the communication area of CS (4) operate as slaves of CS (4).
Under the control of CS (4), there are two CSs (CS (2) and CS (5)) operating as slaves. On the other hand, under the others, that is, under the control of CS (3), CS (6), CS (9), and CS (11), there is only one CS that operates as a slave. Even if CS (4) has the largest bottleneck, there are only two CSs under its control, and even if CS (4) becomes inoperable, the proportion of affected CSs is Less than the total CS number. As described above, the CS placed immediately below the master (CS (7)) in the highest layer can reduce the influence when the master CS becomes inoperable by leveling the bottleneck.

  FIG. 16 shows an example of a communication area when a base station device (for example, CS) is installed across a floor in a building. The CS (10) installed on the first floor is set as a slave of the CS (3) installed on the same first floor in the conventional manual setting operation. If the communication condition between CS (10) and CS (3) is bad, if the installation operator works without noticing the bad communication condition, CS (10) is used with unstable communication. Sometimes.

  By performing the survey process described above, the control unit 111 of the temporary master CS, for example, has a relatively stable CS (8) installed on the second floor and CS (10) installed on the first floor. To detect that communication is possible. Further, since CS (10) is set as a slave of CS (8) installed on the second floor, the burden on the operator can be reduced and a more stable tree configuration can be formed.

  FIG. 17 is an example of a communication path when a base station apparatus (for example, CS) is installed in a wide facility such as a hotel, and CS (1) is the master of the highest layer. The thicker the arrow line in FIG. 17, the stronger the received electric field strength. CS (4) or CS (6) is a bottleneck with many CSs under its control. Since the distance between CS (4) and CS (2) is relatively short, CS (4) is set as a slave of CS (2) in the conventional manual setting operation.

  When CS (4) and CS (1) directly transmit and receive according to the criterion (b) of FIG. 7, Cost (4)-(1) is Cost (2)-(1) and Cost (4). -CS (4) is a slave of CS (1) if it is less than or equal to the sum of (2). Even in consideration of the lower bottleneck of CS (4), it is advantageous to set CS (4) immediately below the master CS (1) of the highest layer.

  Next, an operation after the master CS of the highest layer is formally determined will be described. In the example of the tree configuration shown in FIG. 13, CS (2) is synchronized according to a synchronization signal from a master CS (for example, CS (1)) arranged in a higher layer, and CS (2) is a lower CS. (7) is synchronized according to a synchronization signal from CS (2) as a master. The other CSs synchronize according to the synchronization signal from the upper master CS (2).

The radio communication determination unit 104 of each CS illustrated in FIG. 2 determines whether the radio communication unit 101 has normally received the synchronization signal from the master CS. The wireless communication determination unit 104 determines whether or not the CS wireless communication unit 101 has received the synchronization signal from the master CS at a predetermined reception timing.

  The communication timing correction unit 107 of each CS corrects the communication timing according to the synchronization signal from the CS arranged in the upper layer. That is, during normal operation, each CS determines a correction parameter according to the information on the time lag acquired together with the synchronization signal, and stores it in the storage unit 109. As a result, even if the CS loses the synchronization signal temporarily, each CS can maintain the communication timing at a predetermined timing by this correction parameter, and can maintain the synchronization.

  Next, another example of the bottleneck calculation process will be described. First, similarly to the above-described example, the slave CS (one or more) immediately below each master CS candidate calculates the sum of the slave CSs held under the slave CS immediately below. Next, the ratio of the sum total of the slave CSs to the total CS number is calculated.

  For example, for the master CS candidate CS (1), there are six subordinates of the slave CS (8) directly under CS (1), 50% of the total, and the slave CS directly under CS (1). Assume that one CS under (10) is 7% of the total. Then, when CS (1) is an official master, if the direct CS (8) malfunctions, 50% of the CS becomes unusable.

  In addition, for CS (2) as a master CS candidate, there are two subordinates of slave CS (6) directly under CS (2), 17% of the total, and slave CS directly under CS (2) Assume that the number of CSs under (7) is three and that is 20% of the total. Then, when CS (2) is an official master, if the direct CS (7) malfunctions, 20% of the entire CS becomes unusable.

  In the above example, the narrowest bottleneck is CS (8), and it is determined that the master CS candidate (1) holding this slave CS (8) as the slave CS directly below is not suitable for the master. In this case, CS (2) is determined as the formal master CS.

  The present invention is not limited to the configuration of the above-described embodiment, and any configuration can be used as long as the functions shown in the claims or the functions of the configuration of the present embodiment can be achieved. Is also applicable.

  In the above-described example, the CS control unit 111 defined as the temporary master CS executes the survey operation in accordance with the activation instruction from the PC 700. However, the survey operation may be executed in the PC 700. That is, the PC 700 may execute an operation of setting work to issue an instruction to each CS to collect a Cost value and perform a bottleneck calculation process.

  INDUSTRIAL APPLICABILITY The present invention is useful for a communication system, a base station apparatus, and the like that can form a more stable tree configuration and reduce the burden on an installation worker.

1000 Communication system 100 Base station apparatus (CS)
101 wireless communication unit 102 antenna unit 103 wired communication unit 104 wireless communication determination unit 105 clock generation unit 106 communication timing determination unit 107 communication timing correction unit 108 synchronization state determination unit 109 storage unit 110 learning processing unit 111 control unit 200 communication terminal (PS) )
300 SIP server 400 Telephone 500 Router 600 External network 700 PC
N1 wired network

Claims (3)

A communication system in which a plurality of base station devices communicate by a time division wireless communication method,
Each base station device measures the received electric field strength of signals of other base station devices that can be received,
Reception when any two base station apparatuses capable of communication are connected by a route through which at least one other base station apparatus is interposed, and when they are directly connected without interposing another base station apparatus Compare the electric field strength to determine the route between the two base station devices,
A communication system, wherein a base station apparatus having the smallest number of intervening base station apparatuses is determined as the highest master in the route to another base station apparatus capable of communication. The communication system is a time division communication system in which the plurality of base station devices are synchronized with respect to a master base station device,
2. The communication system according to claim 1, wherein a temporary master base station device until the master base station device is determined is selected, and the plurality of base station devices are synchronized with the temporary master base station device. .   When there are a plurality of base station apparatuses having the smallest maximum number of intervening base station apparatuses, the number of base station apparatuses directly connected to each of the base station apparatuses is detected, and the directly connected base station apparatus is detected. The communication system according to claim 1 or 2, wherein the base station device having the largest number of station devices is set as a new master base station device.

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