JP4871705B2 - Digital wireless communication system - Google Patents

Description

  The present invention relates to a digital wireless communication system, and more particularly, to a digital wireless communication system capable of rapid communication line connection even when communication traffic is crowded.

  As one of the digital radio communication systems in practical use, there is a digital radio communication system defined in the standard ARIB STD-T87 (Association of Radio Industries and Businesses-T87) “Airport MCA Digital Radio Communication System”. is there. This system, for example, provides multi-channel access (MCA) for airports that have an important mission of ensuring the safety of aircraft in the airport area and the comfort of users' activities at each airline. Access) wireless communication system.

  FIG. 6 shows a digital wireless communication system with multiple base station zones. In FIG. 6, reference numeral 601 denotes a control station, 602-1 and 602-2 denote base stations, and 603-1 and 603-2 denote base station zones, that is, communication areas of the respective base stations. The base station 602-1 has a plurality of terminal stations in the communication area 603-1, for example, groups 604-1, 604-2, ... 604-m. In addition, when representing a terminal station group, it is referred to as a terminal station group 604. Each terminal station group 604 is composed of a plurality of terminal stations. For example, the terminal station group 604-1 is composed of terminal stations 605-1, ... 605-10, and the terminal station group 604-m is composed of terminal stations 605-51, ... 605-n. Yes. In addition, when representing a terminal station, it is called a terminal station 605. Similarly, the base station 602-2 has a group 606-1,... 606-p having a plurality of terminal stations in the communication area 603-2. In addition, when representing a terminal station group, it is referred to as a terminal station group 606. Each terminal station group 606 includes a plurality of terminal stations. For example, the terminal station group 606-1 is composed of terminal stations 607-1,... 607-10, and the terminal station group 606-p is composed of terminal stations 607-31,. Yes. The terminal station group is referred to as a terminal station group 606, and the terminal station group is referred to as a terminal station 607.

  This digital wireless communication system is a communication connection service for direct communication between terminal stations 605 and 607 and base stations, between other base stations, or between terminal stations via a base station, or between terminal stations, for example, A communication connection service between a terminal station outside the area 603-1 and a terminal station in the communication area 603-1 is configured to be performed.

  The control station 601 maintains and manages the communication connection and service area between the base station 602 and the plurality of terminal stations 605 and 607 in the digital wireless communication system, and performs call control from the terminal station or setting of a communication route. The control etc. which perform are performed. Note that the control station 601 may be configured integrally with the base station 602-1 or the base station 602-2, or may be installed at a place distant from each other as shown in FIG. In this case, the control station 601 and the base stations 602-1 and 602-2 are generally connected via transmission lines 608-1 and 608-2 such as wired or micro lines. Further, the terminal station described here includes a mobile wireless device, a portable wireless device, an information terminal station, or the like mounted on a vehicle or the like. Further, in the above example, only two base stations are shown, but generally, a system composed of a plurality of base stations and a large number of terminal stations is common, but will be described with reference to FIG. 6 having a simple configuration. .

  FIG. 7 shows an example of radio carrier frequency allocation permitted for use in a digital radio communication system using the digital radio technology defined in the standard ARIB STD-T87. In FIG. 7, for example, in the uplink direction, that is, the direction from the terminal station to the base station, several tens of waves (f1, f2,...) Are recognized with a radio carrier f of 400 MHz band and a width of 25 KHz. In the downlink direction, that is, in the direction from the base station to the terminal station, a radio carrier F that is 44.5 MHz away from the radio carrier in the uplink direction and a width of 25 kHz and several tens of waves (F1, F2,...) Are recognized. It has been. Accordingly, in the communication of the digital wireless communication system, the frequencies in the upstream direction f1, f2,..., The downstream directions F1, F2,. Each system can use one or a plurality of radio carriers according to the scale.

  Further, in the standard ARIB STD-T87, between terminal stations, for example, a terminal station 605-11 located within the communication area 603-1 and a terminal station located outside the communication area 603-1 are directly connected between the terminal stations. A wireless carrier W is allowed to communicate. This wireless carrier W also has a bandwidth of 25 KHz, and a dozen waves (W1, W2,...) Are recognized. In the digital wireless communication system shown in FIG. 6, the base station 602-1 uses, for example, uplink and downlink pair waves (f1, F1), (f2, F2), (f3, F3), and The base station 602-2 performs communication using uplink and downlink pair waves (f5, F5), (f6, F6), and (fm, Fm).

  Further, each radio carrier is divided into frames as shown in FIG. 8, and after the frame is further divided into four slots, control channels C and communication channels S1, S2, S3,. Assigned. Such a communication system is a TDMA (Time Division Multiple Access) digital wireless communication system. Note that the communication channels S1, S2, S3,... S11 are referred to as communication channels S. Here, for example, one frame is 40 ms, and one slot is 10 ms. The control channel C is a channel that performs wireless line connection control and the like, and the communication channel S is a channel that performs telephone calls and data communication. In FIG. 8, only the downlink directions F1, F2, and F3 are shown in the uplink and downlink pair waves. Table 1 summarizes the frame configuration shown in FIG.

  In this example, there are three radio carriers F1, F2, and F3. When one radio carrier is divided into four slots for communication, a total of 12 channels can be used, but one channel is assigned to the control channel C. The remaining 11 channels are used as communication channels S1, S2,... S11.

  In the system shown in FIG. 8 and Table 1, for example, the base station 602-1 shown in FIG. 6 uses, for example, uplink and downlink pair waves (f1, F1), (f2, F2), (f3, F3) And the state which is communicating with each terminal station 605 is shown. Similarly, the base station 602-2 communicates with each terminal station 607 using the uplink and downlink pair waves (f5, F5), (f6, F6), (fm, Fm). In the description, the base station 602-1 and the terminal station 605 belonging to the communication area 603-1 will be described.

  Now, an operation for the terminal station 605 belonging to the communication area 603-1 to perform communication will be described. For example, the case where the terminal station 605-1 belonging to the group 604-1 communicates with the terminal station 605-11 belonging to the group 604-2 will be briefly described. The terminal station 605-1 transmits a connection request signal to the control station 601 through the base station 602-1 using the control channel C shown in FIG. Receiving the connection request signal, the control station 601 searches for an empty channel of the communication channel S shown in FIG. 8, and if there is an empty communication channel S, sends a connection permission signal to the terminal station 605-1 for the control channel C. Use to send. At the same time, the control channel C is used to transmit a communication channel designation signal, for example, the communicable channel S1, to the terminal station 605-1 and the terminal station 605-11. Therefore, the operators of the terminal station 605-1 and the terminal station 605-11 can set the communication channel S1 and perform a voice call by the press talk method.

  In this way, the digital wireless communication system performs a communication operation. However, in such a digital wireless communication system, the digital wireless communication system is operated without stopping throughout the year, and is an operation state in which communication is repeated day and night. Wireless terminal station users are also always required to make a quick call line connection in order to instantly communicate business communications. However, in the digital wireless communication system as described above, the system is composed of hundreds to thousands of terminal stations. For this reason, the load of communication traffic increases during a specific time of the day, and the communication traffic increases during busy hours in the morning and evening. Even if the terminal station is operated, the wireless line is connected. It is difficult or difficult to connect, which hinders the performance of each airline. Therefore, it is desired to realize a digital wireless communication system that can quickly connect a terminal station.

JP-A-10-178673 ARIB STD-T87 “Airport Digital Mobile Communication System”, Japan Radio Industry Association

  Even if the operation status of a digital wireless communication system increases the communication traffic load during a specific time of the day, or the communication traffic increases during the busy hours of morning and evening Therefore, it is desired to realize a wireless communication system that can be connected to a terminal station quickly.

  An object of the present invention is to provide a highly reliable digital wireless communication system.

  Another object of the present invention is to provide a digital radio communication system capable of rapid communication line connection.

  Another object of the present invention is to provide a digital wireless communication system that enables traffic distribution of control signals in response to an increase in communication traffic.

  Another object of the present invention is to provide a digital radio communication system that enables traffic distribution of control signals according to time zones.

  Still another object of the present invention is to provide a digital wireless communication system that can cope with a load of communication traffic generated in response to an accident or a change in weather.

  A digital wireless communication system of the present invention includes a control station, a base station coupled to the control station, and a plurality of terminal stations coupled to the base station via a radio channel, and the radio channel includes a control channel, In a digital radio communication system having a communication channel, the control station has a control unit and a storage unit, and the control unit monitors a call loss rate of the digital radio communication system, and the call loss rate exceeds a predetermined call loss rate. The control unit is configured to increase the number of control channels.

  In the digital wireless communication system of the present invention, the control unit is configured to increase the number of control channels when a period in which the call loss rate exceeds a predetermined call loss rate continues for a predetermined period.

  The digital wireless communication system of the present invention includes a control station, a base station coupled to the control station, and a plurality of terminal stations coupled to the base station through a radio channel, and the radio channel is controlled by In a digital wireless communication system having a channel and a communication channel, the control station has a control unit and a storage unit, and stores a time zone table in which the number of control channels is determined in the storage unit. The channel number of the control channel is set with reference to the time zone table.

  In the digital radio communication system of the present invention, the storage unit stores a control channel allocation table, and when the control unit increases the number of channels of the control channel, the control channel allocation table is transmitted to the plurality of terminal stations. An available control channel is set based on

  As described above, the present invention can realize a digital wireless communication system that has high reliability and can be quickly connected to a communication line. In addition, it is possible to realize a digital wireless communication system that enables an increase in communication traffic and traffic distribution of control signals according to time zones. It is also possible to cope with communication traffic loads that occur due to accidents and changes in weather. Therefore, there is a feature that can realize a digital wireless communication system capable of maintaining a quick communication line connection requested by a user.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to FIGS. The digital radio communication system to which the present invention is applied is substantially the same as the digital radio system shown in FIG. FIG. 1 is a block diagram showing specific configurations of a control station and a base station according to an embodiment of the present invention, and corresponds to the control station 601 and the base station 602 of the digital wireless communication system shown in FIG. The control station 601 is also referred to as a line control device.

  In FIG. 1, reference numeral 101 denotes a control station, and 102 denotes a base station. The control station 101 and the base station 102 are coupled by a transmission line 103 such as a wired or micro line. Note that the control station 101 and the base station 102 can be configured integrally, but can also be provided separately as shown in FIG. Also, a plurality of base stations 102 are usually provided as shown in FIG. 6, but in FIG. 1, only one station is shown as a representative for the sake of simplicity. The control station 101 has a control unit 104, a storage unit 105, and a control table 106. The control table 106 includes an operation display unit 107, a microphone 108, and a speaker 109. Also, the base station 102 receives a signal from the base station to the terminal station, for example, a transmission radio 110 that transmits the signal from the radio carrier F1, and a reception radio 111 that receives a signal from the terminal station, for example, by the radio carrier f1. It consists of In FIG. 1, only the receiving wireless device 111 that receives the signal from the transmitting wireless device 110 and the terminal station, which is transmitted by the wireless carrier F1, is received by the wireless carrier f1, but is transmitted by the wireless carriers F2 and F3. It goes without saying that a transmission radio (not shown) and a reception radio (not shown) for receiving signals from the terminal stations by radio carriers f2 and f3 are also provided.

  The control station (line control device) 101 has a function of managing the channel usage status (communication channel usage status) of multi-channel access, a function of creating and transmitting control information to the base station 102, and a reception by the base station 102. For example, a function for analyzing the received control information, or a function for instructing the terminal station 605 to use a line (communication channel to be used) by receiving or transmitting the control information. In other words, the control station 101 maintains and manages a communication connection and a service area between the base station radio apparatus 602 (base station 102) and the plurality of terminal stations 605 and 607 (terminal station 200) in the digital radio communication system. Control for making a call from a terminal station or setting a communication route is performed.

  In addition, the base station 102 (corresponding to 602) has a function of wirelessly communicating signals such as control information and voice information with the terminal station 605 existing in the communicable range, and the control station 101 (corresponding to 601 only). A function of communicating a signal such as control information. Specifically, the base station 102 receives and demodulates control information transmitted from each terminal station 605 by radio and passes the control information to the control station 101 and modulates the control information output from the control station 101 to each terminal. A function of transmitting to a station by radio is provided.

  FIG. 2 is a block diagram showing a specific configuration of a terminal station according to an embodiment of the present invention, and corresponds to the terminal stations 605 and 607 of the digital radio system shown in FIG. Note that the terminal station described here includes a mobile wireless device, a portable wireless device, an information terminal station, or the like mounted on a vehicle or the like. In FIG. 2, the terminal station 200 (corresponding to the terminal stations 605 and 607) uses, for example, a paired wave of an uplink radio carrier f1 and a downlink radio carrier F1, and can perform voice communication using the press talk method. The device is shown. The terminal station 200 is assumed to represent a plurality of terminal stations. In FIG. 2, 201 is an antenna for transmitting / receiving to / from the base station 102, 202 is a changeover switch for transmitting / receiving to / from the base station 102, 203 is a receiving unit, 204 is a received signal processing unit, and 205 is , A speaker, 206, a control unit, 207, a storage unit, 208, a display unit, 209, an operation unit, 210, a microphone, 211, a transmission signal processing unit, and 212, a transmission unit. The apparatus shown in FIGS. 1 and 2 will be described as a press talk type apparatus, but may be a simultaneous transmission / reception system.

  Now, a case where the terminal station 200 performs communication will be described. For example, an operation for the terminal station 605 (same as the terminal station 200) belonging to the communication area 603-1 to perform communication will be described. For example, the case where the terminal station 605-1 belonging to the group 604-1 communicates with the terminal station 605-11 belonging to the group 604-2 will be described. First, the terminal station 605-1 transmits a connection request signal to the control station 601 through the base station 602-1 using, for example, the control channel C shown in FIG. The signal frame format of this control channel C is shown in FIG. In FIG. 4, symbols for each part are R: burst transient response guard time, P: preamble, CAC: control signal (including PCH, BCCH, and SCCH), PCH: general call channel, BCCH: broadcast channel, SCCH: individual Zone signaling channel, E: collision control bit, SW: synchronization word, CI: carrier information, CC: color code (interference countermeasure code), I: idle bit. The number represents the number of bits. The connection request signal is transmitted as, for example, a code “0001” as shown in Table 2 using 4 bits of the control signal CAC.

  Receiving the connection request signal (code “0001”), the control station 601 searches for an empty channel of the communication channel S shown in FIG. 8, and if there is an empty communication channel S, for example, an empty communication channel S1, The connection permission signal is transmitted to the terminal station 605-1 as, for example, a code “0010” shown in Table 2 using 4 bits of the control channel CAC of the control channel C shown in FIG. At the same time, the control station 601 transmits a communication channel designation signal using the control channel C, for example, an empty channel S1 (communication available channel) to the terminal station 605-1 and the terminal station 605-11 using the control channel. . Therefore, the operators of the terminal station 605-1 and the terminal station 605-11 can set the terminal station to the communication channel S1 and perform a voice call by the press talk method.

  FIG. 5 shows a signal frame format of the communication channel shown in FIG. In FIG. 5, symbols of each part are R: burst transient response guard time, P: preamble, TCH: traffic channel, SW: synchronization word, CI: carrier information, CC: color code (interference countermeasure code), FACCH: high speed ACCH, SACCH: Low-speed ACCH, RCH: Housekeeping channel, B / I: Busy / Idle bit. The number represents the number of bits. For example, voice for a call is performed using the traffic channel TCH.

  Thus, in the digital wireless communication system described above, when a connection request signal is transmitted from the plurality of terminal stations 200 to the control station 101 via the base station 102 using the upstream control channel C, the control of the control station 101 is performed. The unit 104 constantly monitors the communication channel S shown in FIG. 8, detects an empty communication channel S in response to the connection request signal from the terminal station 200, and sends the empty communication channel S to the requested terminal station 200. The communication channel S is assigned, so that the communication is always performed by dynamically allocating a plurality of communication channels to the plurality of terminal stations 200 and performing wireless communication.

  Thus, the control channel C exchanges control signals between the base station 102 and the terminal station 200 at the start or end of a call, and controls terminal state information when the terminal station 200 is turned on / off. It is used for transmission / reception of a control signal for notifying the control station 101 of a report to the station 101 and a location registration of the connected terminal station 200. Therefore, the communication traffic of the control channel C increases when the number of terminal stations 200 in operation is large or when the number of outgoing calls is large.

  When the communication traffic of the control channel C increases, when the control station 101 or the terminal station 200 tries to output a control signal, the terminal that has collided with the control signal output by another terminal station 200 and has issued the control signal later The station 200 needs to perform retransmission (retry). When a large number of control signal retransmissions (retry) occurs, the timing for transmitting a call channel assignment or connection permission signal to a plurality of terminal stations 200 is delayed, and a quick communication line assignment or transmission right assignment requested by the user is performed. Will not be able to.

  In particular, in a digital wireless communication system, a system is composed of hundreds to thousands of terminal stations. For this reason, the load of communication traffic increases during a specific time of the day, and the communication traffic increases during busy hours in the morning and evening. Even if the terminal station is operated, the communication line is connected. It is difficult or difficult to connect, which hinders the performance of each airline.

  In the present invention, the control unit 104 of the base station 101 allows the communication from the plurality of terminal stations 200 in order to eliminate the state where the communication line is not connected or difficult to connect even if the terminal station is operated as described above. The number of calls (number of connection requests) is constantly monitored, and when there are many signal collisions on the control channel, in other words, the number of calls that are not connected to the number of calls, that is, when the call loss rate is a predetermined value or more. The control is performed so as to increase the number of control channels C. Here, the call loss rate A% is expressed by the following equation.

A = (Number of connection failures / number of calls per unit time) × 100 (1)
According to the inventor's experiment, if the call loss rate A is 3% or less (when A <3%) as shown in Table 3, for example, the terminal station is operated even if the control channel C is one channel. There is no state where the communication line is not connected or difficult to connect, but when the call loss rate A exceeds 3% (when A ≧ 3%), the terminal station is operated unless the control channel C is set to 2 channels. In this case, it has been found that the state where the communication line is not connected or difficult to connect cannot be solved. In the embodiment of the present invention, the case in which the call loss rate A is set to 3% as a threshold and the number of control channels is controlled has been described. . Further, even if the control channel C is changed to 2 channels, when the call loss rate A exceeds 3% (when A ≧ 3%), it is possible to further control the number of control channels.

  In order to realize such control, in the present invention, the call loss rate table shown in Table 3 is stored in advance in the storage unit 105 of the control station 101. Then, the control unit 104 of the control station 101 constantly monitors the call loss rate of the digital radio communication system. If the call loss rate A exceeds 3% (A ≧ 3%), the number of control channels C is set to 2. It is controlled to be a channel.

  This will be described with reference to FIG. 3 and Table 4. FIG. 3 is a diagram showing an embodiment of a frame configuration to which the present invention is applied. FIG. 3 shows three radio carriers in the downlink directions F1, F2, and F3, but the uplink radio carriers f1, f2, and f3 have the same frame configuration (not shown). In FIG. 3, the radio carrier F1 has a three-channel configuration of a control channel C1 and communication channels S1, S2, and S3, and the radio carrier F2 has a three-channel configuration of a control channel C2 and communication channels S4, S5, and S6. The wireless carrier F3 has a four-channel configuration of communication channels S7, S8, S9, and S10. This channel configuration is shown in Table 4.

  That is, there are three radio carriers and a 12-channel configuration, but the radio carrier F1 has one control channel C1 and three communication channels, and the radio carrier F2 has one control channel C2 and three communication channels. The wireless carrier F3 has four communication channels. That is, the digital wireless communication system includes two control channels and ten communication channels. Thus, when the call loss rate A exceeds 3% (when A ≧ 3%), when the terminal station is operated by increasing the control channel C to 2 channels C1 and C2, the wireless line is not connected, The state where it is difficult to connect can be solved.

  Now, the control unit 104 of the control station 101 constantly monitors the number of calls (number of connection requests) from a plurality of terminal stations 200, and when the call loss rate A is 3% or less (when A <3%), The control channel C of the digital radio communication system is changed from 2 channels to 1 channel. As described above, the control unit 104 of the control station 101 monitors the call loss rate A of the digital wireless communication system, and performs control so that the control channel is switched to 1 channel or 2 channels according to the call loss rate A.

  Thus, when the control unit 104 of the control station 101 constantly monitors the call loss rate A of the digital wireless communication system and switches the control channel to 1 channel or 2 channels according to the call loss rate A, for example, the call loss rate A is mainly 3%. As a result, there are cases where it goes up and down frequently. In such a case, the control unit 104 of the control station 101 frequently repeats the operation of switching the control channel of the digital wireless communication system to one channel or two channels. In such a case, the operation of the digital wireless communication system becomes unstable, which is not a preferable system from the viewpoint of reliability. Therefore, in the present embodiment, for example, when the call loss rate A exceeds 3% (when A ≧ 3%) exceeds a predetermined time T, for example, 5 minutes, the control channel C is increased to 2 channels C1 and C2. Is to control. In this way, since the control unit 104 of the control station 101 can suppress the operation of frequently switching the control channel of the digital radio communication system to one channel or two channels, a stable digital radio communication system can be obtained. The predetermined time T can be appropriately set according to the system configuration, purpose of use, etc., such as 3 minutes or 10 minutes. The predetermined time T is stored in the storage unit 105 in advance. The setting and changing of the predetermined time T can be performed on the operation display unit 107.

  Next, when the control channel C is increased to two channels C1 and C2 as in the above-described embodiment, the terminal station 200 is confused unless the control channel C1 and the control channel C2 are used separately. Become. Therefore, in another embodiment of the present invention, a method for solving this will be described with reference to Table 5. The digital wireless communication system shown in FIG. 6 is divided into a communication area 603-1 and a communication area 603-2, and terminal stations 605 and 607 grouped exist in these communication areas. In this embodiment, the terminal station 605 in the communication area 603-1 will be described for simplicity, but the same applies to the terminal station 607 in the communication area 603-2.

  In the communication area 603-1, there are a base station 602-1 and a group of terminal stations 604-1, 604-2,. Therefore, a control channel allocation table is created for these groups as shown in Table 5, and the groups that can use the control channels C1 and C2 are divided into groups.

  In Table 5, when the control channel is one channel, all the groups 604-1, 604-2,... 604-m belonging to the communication area 603-1 use one control channel C. For example, when the call loss rate A of the system exceeds 3%, the terminal stations using the control channel C1 are the terminal stations 605 belonging to the groups 604-1 and 604-2, and the terminal stations using the control channel C2 are , The terminal stations 605 belonging to the groups 604-3,... 604-m are determined in advance. The control channel allocation table shown in Table 5 is stored in advance in the storage unit 105 of the control station 101 and the storage unit 207 of the control unit 206 of each terminal station 200. When the control unit 104 of the control station 101 detects that the call loss rate A of the digital wireless communication system exceeds 3%, the control unit 104 sets the control channel of the digital wireless communication system to C1 and C2 to each terminal station 200. Notice.

  As a notification method, the control unit 104 of the control station 101, for example, sends a control channel change signal to a code “0011” as shown in Table 2 and uses all the control channels C belonging to the communication area 603-1. The terminal station 605 (corresponding to the terminal station 200) is notified. When the terminal station 605 receives the code “0011” of the control channel change signal, the terminal station 605 decodes this code, refers to the control channel allocation table shown in Table 5 stored in the storage unit 207 of the control unit 206, and uses it. It is determined whether the control channel to be used is C1 or C2. By doing so, even if the control channel is changed from C of one channel to C1 and C2 of two channels, each terminal station 605 knows the control channel that can be used by itself, and thus is not confused.

  Next, another embodiment of the present invention will be described with reference to FIG. In the above embodiment, the control unit 104 of the control station 101 monitors the call loss rate A of the digital wireless communication system and controls the number of control channels according to the call loss rate A. The embodiment shown in FIG. 9 is a method for controlling the number of control channels according to the time zone. In FIG. 9, the vertical axis represents the call loss rate, and the horizontal axis represents time, for example, one day, 24 hours. Lines 901 and 902 indicate time periods when the call loss rate exceeds 3%, for example. In FIG. 9, the call loss rate exceeds 3% at 6:00 to 10:00 and 16:00 to 20:00 in the time zone of one day. In other time zones, the call loss rate is 3% or less. In such a case, the control unit 104 of the control station 101 sets the control channel to 2 channels in the time zone of 1 day between 6 o'clock and 10 o'clock and 16:00 to 20:00, and other time zones Is controlled to be one channel. Specifically, the time zone table shown in Table 6 is stored in the storage unit 105 of the control station 101, and the control unit 104 of the control station 101 controls the number of control channels based on this time zone table.

  In Table 6, the control channel is 1 channel for the time zone, 0 o'clock to 6 o'clock, 10 o'clock to 16 o'clock, 20 o'clock to 24 o'clock, and the control channel is 2 channels at 6 o'clock to 10 o'clock, and 16:00 to 20:00 It is shown that. It should be noted that the control channel is set to 2 channels at just 6:00, 10:00, 16:00, and 20:00. The time zone table shown in Table 6 can be realized by measuring the call loss rate A and operating the operation display unit 107 and setting the time zone and the like in advance while the digital wireless communication system is operating.

  If the time zone table is set in this way, the control unit 104 of the control station 101 does not always have to monitor the call loss rate A of the digital wireless communication system. For example, a timer provided in the control unit 104 of the control station 101 Since the number of control channels can be increased or decreased based on the time zone table as time elapses (not shown), the control unit 104 is freed from the burden of constantly monitoring the call loss rate A. Needless to say, the time zone table shown in Table 6 may be changed variously depending on the season and on Sundays and holidays.

  Furthermore, when an accident occurs at the airport or when it is snowing, the number of calls from the terminal station increases drastically, so that the operator operates the operation display unit 107 of the control station 101 to forcibly control it. Channels can be increased to two channels or more.

  The configurations of the control station, base station, and terminal station of the digital wireless communication system according to the embodiment of the present invention described above are not necessarily limited to those described above, and various configurations can be used. The application field of the present invention is not necessarily limited to the above-described fields, and the present invention can be applied to various fields. For example, the present invention can be applied not only to communication of voice information but also to communication of various information such as text and images.

  Although the present invention has been described in detail above, the present invention is not limited to the embodiments of the digital radio communication system described herein, and can be widely applied to other digital radio communication systems. Needless to say.

The block diagram of schematic structure of the control station and base station used by this invention is shown. The block diagram of schematic structure of the terminal station used by this invention is shown. It is a figure for demonstrating the flame | frame structure used by this invention. It is a figure for demonstrating the frame structure of the control channel used by this invention. It is a figure for demonstrating the frame structure of the communication channel used by this invention. It is a block diagram which shows an example of the conventional digital radio | wireless communications system. It is a figure for demonstrating the relationship of the radio | wireless carrier frequency used with the conventional digital radio | wireless communications system. It is a figure for demonstrating the frame structure of the conventional digital radio | wireless communications system. It is a figure for demonstrating another Example of this invention.

Explanation of symbols

  101, 601: Control station, 102, 602: Base station, 103, 608: Transmission path, 104, 206: Control unit, 105, 207: Storage unit, 106: Control table, 107: Operation display unit, 108, 210: Microphone, 109, 205: Speaker, 110: Radio for transmission, 111: Radio for reception, 200, 605, 607: Terminal station, 201: Antenna, 202: Changeover switch, 203: Receiver, 204: Received signal processing Part, 205: speaker, 208: display part, 209: operation part, 211: transmission signal processing part, 212: transmission part, 603: communication area, 604, 606: terminal station group.

Claims (3)

In a digital radio communication system having a control station, a base station coupled to the control station, and a plurality of terminal stations coupled to the base station through a radio channel, the radio channel having a control channel and a communication channel ,
The control station has a control station storage unit, the 該統system station memory unit, a time frame table that defines the number of control channels that can be used depending on the time zone, the control channels according to the number of control channels available And a control channel assignment table assigned to each control channel by a terminal station that can use
The terminal station has a terminal station storage unit, and a control channel allocation table in which terminal stations that can use each control channel according to the number of usable control channels are allocated to the terminal station storage unit for each control channel Remember
When the control station increases the number of control channels that can be used in the time zone based on the time zone table, the terminal station uses the control channel allocation table stored in the terminal station storage unit to A digital wireless communication system, characterized in that a control channel to be used by a station is determined . A digital wireless communication system according to claim 1, wherein
When the control station increases the number of control channels that can be used in the time zone based on the time zone table, the control station notifies the terminal station of a control channel change signal using the control channel. A digital radio communication system , which receives a control channel change signal, determines a control channel to be used by the terminal station based on a control channel allocation table stored in the terminal station storage unit . In a digital radio communication system having a control station, a base station coupled to the control station, and a plurality of terminal stations coupled to the base station through a radio channel, the radio channel having a control channel and a communication channel ,
The control station and the terminal station each have a control station storage unit and a terminal station storage unit, and each control channel is assigned to the control station storage unit and the terminal station storage unit according to the number of control channels that can be used. An available terminal station stores a control channel assignment table assigned to each control channel,
When the control station increases the number of control channels that can be used, the terminal station determines a control channel to be used by the terminal station based on a control channel allocation table stored in the terminal station storage unit. A digital wireless communication system.

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