Radio communication method

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a base station dependent system used for digital wireless communication.

【0002】

[Conventional technology]

A digital wireless system is generally composed of one base station and a plurality of terminal stations. By synchronizing each terminal station with the timing of the base station, multiple connections that secure a plurality of lines at the same time are realized. Taking TDMA (Time Division Multiple Access), which is one of the multiple access methods, as an example, the concept of a multiplex system will be explained with reference to FIG.

【0003】

FIG. 5 is a diagram showing how communication is performed between two terminal stations and a base station in a TDMA system. 101 is a base station, 102 is a terminal station A, 103 is a terminal station B, 104-1 is a downlink signal transmitted from the base station 101 to the terminal station A102, and 104-2 is transmitted from the base station 101 to the terminal station B103. The downlink signal, 105-1 is an uplink signal transmitted from the terminal station A102 to the base station 101, and 105-2 is an uplink signal transmitted from the terminal station B103 to the base station 101. In FIG. 5, the wireless carrier is composed of a pair of uplink / downlink frequencies, the downlink frequency is F, and the uplink frequency is f. Multiplexing is realized by time-dividing the pair of frequencies as shown in FIG.

【0004】

FIG. 6 is a diagram showing slots of a conventional time division multiplexing system. FIG. 6 shows an example when the number of multiplex is 4. 106 is the frame delimiter for the downlink signal, 107 is the frame delimiter for the uplink signal, 108-1,2,3,4 is the slot for the downlink signal, 109-1,2,3,4 is the slot for the uplink signal, 110 is the time axis. Is. In FIG. 6, in the downlink direction (transmission from the base station 101 to the terminal station A102 or the terminal station B103), one radio carrier is divided into frames 106 on the time axis, and the frame 106 is further divided into slots corresponding to the multiplex number 4. (SLOT1, SLOT2, SLOT3, SLOT4) Multiplexing is performed by dividing into 108-1,2,3,4. In the example of Fig. 6, one frame is 40 msec.

【0005】

Slots 108-4 are assigned to one control channel (CCH), and slots 108-1, 108-2, 108-3 are assigned to three communication channels (TCH1, TCH2, TCH3). The control channel (slot 108-4) is a channel that controls the connection of lines, and the communication channel (slots 108-1, 108-2, 108-3) is a channel that performs communication such as telephone communication and data transmission. Base stations usually transmit all these slots at all times. On the other hand, in the up direction, the frame timing 107 based on the down frame 106 is divided into slots 109-1,2,3,4, and slot 109-4 has one control channel (CCH) as in the case of down. Slots 109-1, 109-2, 109-3 are assigned to three communication channels (TCH1, TCH2, TCH3). The terminal station (terminal station A102 or terminal station B103) has only the control channel (slot 109-4) or the communication channel slot (one of slots 109-1, 109-2, 109-3) specified by the base station 101. To send. In the example of this figure, the terminal station A102 transmits at the timing of slot 109-1, and the terminal station B transmits at the timing of slot 109-2.

【0006】

As described above, the multiplexing method in which a plurality of terminal stations individually perform uplink transmission in a slot designated by a base station is called TDMA (Time Division Multiple Access). In addition, TDM (Time Division) is a method in which a base station transmits through slots assigned to multiple terminal stations and the terminal station receives the slots assigned to its own station. Called Multiple). A general call connection means for performing such communication will be described. In the case of a terminal station call, the terminal station transmits a connection request signal in the slot specified for the control channel, for example, 1 to 2 frames, and the base station that receives the connection request signal is assigned for communication. At the same time as setting an empty slot from the slots as a communication channel, the terminal station is notified of this setting through the control channel, and the transmission slot of the terminal station is switched. On the other hand, in the case of a base station call, the base station checks for the presence or absence of a free channel in the communication channel, and if there is a free channel, the base station sends a call signal to the target terminal station on the control channel, and then. , Set an empty communication channel as the communication channel. In order to establish the above system, it is necessary to accurately control the transmission slot timing of the terminal station in order to prevent interference between the slots. Therefore, the base station constantly transmits a signal including the control channel (control channel signal), and the terminal station receives this control channel signal at any time when necessary to synchronize the slot timing with the base station. It is necessary to maintain a state in which it is possible.

【0007】

As mentioned above, the base station-dependent wireless systems that the base stations constantly transmit are the Association of Radio Industries and Businesses standard ARIB STD-27 (digital car phone system) and ARIB STD-39 (digital mobile communication for public business). It is used in TDMA systems such as (system). In addition, even in systems other than TDMA, for example, SCPC / FDMA (Single Channel Per Carrier / Frequency Division Multiple Access) systems used in ARIB STD-T61 (Narrowband Digital Communication System), the base station constantly transmits control channels. The terminal station receives this and establishes the synchronization of the frame timing, and also synchronizes the frequency. As a result, the accuracy of the transmission frequency of each terminal station is ensured, and interference with other channels is suppressed. Further, the fact that the terminal station synchronizes the frame with the base station also has an effect of facilitating the reception operation of the base station.

【0008】

[Problems to be Solved by the Invention]

In the above-mentioned prior art, in a base station-dependent wireless system, the base station needs to constantly transmit a control channel signal. In such a base station regular transmission system, for example, when the frequency of outgoing calls is very low in normal times such as disaster prevention radio, or when the frequency of connection is significantly reduced even in a normal system. However, it must always maintain a standby state for calls from the terminal station. Therefore, there is a drawback that the burden is large in terms of the power consumption of the transmitter of the base station. In particular, some systems are equipped with batteries so that they can be operated within a certain period of time even during a power outage, and such a system requires a system operation method with even higher power efficiency. An object of the present invention is to provide a wireless system and a method of operating the system by eliminating the above-mentioned drawbacks and reducing power consumption.

【0009】

[Means for solving problems]

In order to achieve the above object, the wireless communication method of the present invention puts the transmitter of the base station in a stopped state when there is no communication within a certain period of time, and when the terminal station makes a call during this period, the terminal station Sends a transmission start request signal to the base station, and the base station receives this signal and restarts the transmitter.

【0010】

That is, the wireless communication method of the present invention is a digital wireless system composed of at least a base station and a plurality of terminal stations, in which the base station constantly transmits a control channel signal and the plurality of terminal stations transmit the control channel signal. In a base station-dependent wireless communication method that receives and synchronizes with the frame timing of the base station to match the frame timing, the base station monitors the connection status of the line and a predetermined time after the last call ends. If there is no call connection request within, the base station shuts down the transmitter.

【0011】

Further, in the wireless communication method of the present invention, each of the plurality of terminal stations detects whether or not the transmitter of the base station is in the stopped state, and as a result of the detection, the transmitter of the base station is in the stopped state. Is to transmit a transmission activation request signal to the base station. Further, after transmitting the transmission start request signal to the base station, the terminal station performs a reception operation, receives the control channel signal of the base station, and establishes synchronization with the received control channel signal. A normal call is made after the synchronization is established.

【0012】

Furthermore, in the wireless communication method of the present invention, when the transmitter of the base station is in the stopped state, the base station is stopped when it receives a transmission start request signal transmitted from at least one of a plurality of terminal stations. Activate the transmitter of the base station in the state and start transmitting the control channel signal. Also, when the terminal station transmits a transmission activation request signal, the base station identifies the terminal station that transmitted the transmission activation request signal, and when the identified terminal station is in the zone of the base station, it is in a stopped state. It activates the transmitter of the base station in the above and starts the transmission of the control channel signal. Furthermore, when the base station of the wireless communication method of the present invention receives the transmission activation request signal, it identifies the terminal station that transmitted the transmission activation request signal, and the specified terminal station is in the zone of the base station. Occasionally, it activates the transmitter of a stopped base station and assigns a communication channel to the specified terminal station. Further, the terminal station of the wireless communication method of the present invention confirms the synchronization of reception of the signal transmitted from the base station, and if the synchronization of reception is established, makes a normal call. In addition, the terminal station of the wireless communication method of the present invention confirms the synchronization of reception of signals transmitted from the base station, and if reception synchronization is not established, detects that the transmitter of the base station is in a stopped state. It is a thing.

【0013】

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of the present invention will be described with reference to FIG. Hereinafter, in the description of the examples of the present invention, the TDMA system shown in FIG. 5 and the frame configuration shown in FIG. 6 are used at any time. FIG. 1 is a diagram for explaining the operation of an embodiment of the present invention. FIG. 1 (a) is a basic configuration diagram of a base station, where 11 is a base station control device, 12 is a radio device, 13 is a mode switch, and 14 is an antenna. In FIG. 1A, the base station control device 11 gives transmission data, control signals, and the like to the wireless device 12, and at the same time, inputs received data, status signals, and the like from the wireless device 12. The wireless device 12 includes at least a transmitter and a receiver, and transmits and receives transmission data via the antenna 14 in response to a signal given from the base station control device 11. At the same time, the base station control device 11 gives a control signal to the mode switcher 13. The mode switch 13 receives a control signal given from the base station control device 11 and controls the operation mode of the wireless device 12.

【0014】

The operation mode of the wireless device 12 will be described with reference to FIG. 1 (b). FIG. 1B is a diagram illustrating an operation mode of the wireless device 12. 21 to 24 are timings for explanation, 25 is a transmission output signal, 26 is an operation mode switching signal, 27 and 29 are normal transmission modes, and 28 is a standby mode. The horizontal axis is time. In FIG. 1 (b), the transmission output 25 shows the output of the antenna 14, and the operation mode switching signal 26 shows the output of the mode switch 13. As shown in this figure, the wireless device 12 is switched between the normal mode 27 or 29 and the standby mode 28 according to the operation mode switching signal.

【0015】

In the normal delivery mode 27 or 29, the operation is performed according to the operation according to the prior art. That is, the base station 101 transmits the slot (CCH108-4) including the control channel by the transmitter, so that the terminal station A102 or the terminal station B103 that can receive the slot (CCH108-4) can secure the synchronization. On the other hand, in the standby mode 28, the base station 101 always stops the transmission of the slot including the control channel, and then listens for the signal from the terminal station A102 or the terminal station B103. That is, the transmitter of the wireless device 12 is stopped and waits for a signal from the terminal station A102 or the terminal station B103. In FIG. 1 (b), the following conditions are required to shift the operation mode of the wireless device 12 from the normal transmission mode 27 to the standby mode 28, which occurs at the time shown at the timing 21. That is, basically, during the period of the normal delivery mode 27, if there is no line connection within a predetermined predetermined time, the mode shifts to the standby mode 28. However, in an emergency or the like, the transition to the standby mode 28 is prohibited by the setting of the operator of the base station 101 or the control signal from the control station (not shown in FIG. 5) that controls the corresponding radio zone. If so, even if there is no line connection within the predetermined time, the standby mode 28 is not entered and the normal delivery mode 27 is maintained.

【0016】

In order to realize such a condition, the mode switch 13 is made to perform an operation according to the flowchart shown in FIG. FIG. 2 is a flowchart showing an embodiment of the operation mode transition process of the base station of the present invention. In FIG. 2, in the transition prohibition confirmation step 101, if the mode switch 13 is set to prohibit the transition to the standby mode, the normal forward mode is maintained and the transition prohibition confirmation step 101 is repeated (standby, the normal forward mode). (Maintaining). If the prohibition of transition to the standby mode is not set, the process proceeds to step 102.

【0017】

In the time calculation step 102, the time T from the end time of the last call to the current time is calculated, and the process proceeds to step 103. In the time comparison step 103, if the time T exceeds the preset value L, the process proceeds to step 104, and if the time T is within the preset value L, the process returns to step 101. In the standby mode transition step 104, the mode switch 13 gives the wireless device 12 an operation mode switching signal 26 for shifting to the standby mode. In this way, when the operation mode switching signal 26 is given to the wireless device 12, the wireless device 12 switches the operation mode from the transmission mode 27 to the standby mode 28.

【0018】

Next, the transition conditions for transitioning from the standby mode 28 to the normal delivery mode 29 will be described with reference to the flowchart shown in FIG. FIG. 3 is a flowchart showing an embodiment of the operation mode transition process in the base station 101 of the present invention. In the forced continuous mode confirmation step 201, when a control signal given from the base station 101 or the control station that controls the corresponding wireless zone forcibly instructs the transition to the regular transmission mode, the forced normal transmission mode is executed. The transition step 207 is performed to shift to the normal feed mode. If there is no instruction to shift to the normal delivery mode, the process proceeds to step 202.

【0019】

In the call request confirmation step 202, it is confirmed whether or not to make a call from the base station 101 itself, and if the call is to be made, the process proceeds to the normal transmission mode transition step 207, and the base station 101 shifts to the normal transmission mode. The terminal station (terminal station A102 or terminal station B103) makes a normal call with time to establish synchronization. If there is no instruction to make a call, the process proceeds to step 203.

【0020】

In the reception operation step 203, the base station 101 in the standby mode constantly performs the reception operation, waits for the transmission activation request signal transmitted from the terminal station, and proceeds to step 204. In the synchronization confirmation step 204, since the frame timing of the terminal station is uncertain, synchronization that is not based on the timing of the own station is required for reception in the standby mode. Proceed to step 205. Therefore, the transmission start request signal transmitted from the terminal station depends on the performance of the wireless device 12 of the base station 101, but is, for example, about 25 frames (for example, if one frame is 40 msec, it is 1). It is transmitted continuously during sec). That is, the length of transmitting the transmission start request signal is longer than that of the connection request signal because the base station and the terminal station are not synchronized. In the terminal station identification step 205, the received signal identifies the terminal station that transmitted this signal, and the process proceeds to step 206. In the base station zone confirmation step 206, if the received signal is a transmission activation request signal from within the own base station zone, the process proceeds to step 207, and if not, the process returns to step 201. In the normal delivery mode transition step 207, the normal delivery mode is shifted. As described above, it is most important that the terminal station A102 or the terminal station B103 has a function of shifting to the normal delivery mode even when there is a request for a call.

【0021】

Next, the operation of the terminal station in the standby mode will be described with reference to the flowchart shown in FIG. FIG. 4 is a flowchart showing an embodiment of the terminal station operation of the present invention. When a call request is made at the terminal station A102 or the terminal station B103, the processing of the flowchart of FIG. 4 starts. First, in the reception synchronization confirmation step 301, the reception synchronization is confirmed, and if the reception synchronization is established (it is detected that the transmitter of the radio device 12 of the base station 101 is not in the stopped state), the process proceeds to step 305, which is normal. Make a call (ie, send a connection request signal to base station 101). If reception synchronization is not established, it is detected that the transmitter of the wireless device 12 of the base station 101 is in the stopped state, and the process proceeds to step 302. Transmission activation signal In transmission step 302, as a result of detection, it is determined that the base station 101 is in the standby mode, a transmission activation request signal is transmitted to the base station 101, and the process proceeds to step 303. Upon receiving this transmission activation request signal, the base station 101 performs steps 203 to 207 in FIG. 3, shifts to the normal transmission mode, and starts transmitting the control channel signal. In the reception synchronization establishment operation step 303, the control channel signal transmitted from the base station 101 is received to establish the reception synchronization, and the process proceeds to step 304. In the reception synchronization confirmation step 304, the reception synchronization is confirmed, and if the reception synchronization is established, the process proceeds to step 305 to make a normal call. If the reception synchronization is not established, the process proceeds to step 303, steps 303 and 304 are repeated to wait for the synchronization to be established, and when the synchronization is established, a normal call is made in step 305.

【0022】

Alternatively, after the base station 101 shifts to the normal transmission mode, it is possible to make a call to either the terminal station A102 or the terminal station B103 that has transmitted the transmission activation request. That is, in FIG. 4, after the processing of steps 301 to 302, the base station 101 receives the transmission activation request signal transmitted from the terminal station, and the synchronization confirmation step 204, the terminal station identification step 205, and the base station in FIG. The processing described in the zone confirmation step 206 and the normal transmission mode transition step 207 is performed, and a normal call is made to the terminal station that has transmitted the transmission activation request signal. In this case, the terminal station does not normally perform the call step 305, but waits for the call transmitted from the base station.

【0023】

In the above embodiment, the base station shifts to the standby mode when there is no line connection within a predetermined predetermined time, but the base station may shift to the standby mode at a fixed cycle, or at a fixed cycle. You may return to the normal delivery mode. Further, in the above embodiment, in the terminal station identification step 205 and the base station zone confirmation step 206, the terminal station that has transmitted the transmission activation request signal is identified, and if it is a transmission activation request signal from within the own base station zone, it is usual. Although it has shifted to the transmission mode, it may shift to the normal transmission mode even if it is a transmission activation request signal from outside the own base station zone, and further, without identifying the terminal station that transmitted the transmission activation request signal. You may shift to the normal delivery mode. Further, in the above embodiment, as a method for the terminal station to detect whether or not it is in the normal delivery mode, whether or not synchronization is established is used as a criterion for determination. Whether or not the received electric field strength of the signal is equal to or less than a predetermined value may be used as a criterion, or other means may be used.

【0024】

[Effect of the invention]

As described above, according to the present invention, in the case of a system in which calls are generated very infrequently in normal times or in a system in which the frequency of connections is significantly reduced, it is necessary to stop the transmission operation of the base station. By restarting the transmission at times, it is possible to operate the system by suppressing unnecessary transmission operations and saving the power consumption of the base station. Further, according to the present invention, in a base station-dependent system, it is possible to realize a system capable of connecting by calling from a terminal station at an arbitrary time including a case where the base station has stopped transmission.

[Simple explanation of drawings]

[Figure 1]

The figure for demonstrating the operation of one Embodiment of this invention.

[Figure 2]

The flowchart which shows one Example of the operation mode transition process of the base station of this invention.

[Fig. 3]

The flowchart which shows one Example of the operation mode transition process of the base station of this invention.

[Fig. 4]

The flowchart which shows one Example of the terminal station operation of this invention.

[Fig. 5]

The figure which shows the state of communication between a conventional terminal station and a base station.

[Fig. 6]

The figure which shows the slot of the conventional time division multiplexing system.

[Explanation of symbols]

11: Base station control device, 12: Radio device, 13: Mode switch, 14: Antenna, 21 ~ 24: Timing, 25: Transmission output signal, 26: Operation mode switching signal, 27, 29: Normal mode, 28 : Standby mode, 101: Base station, 102: Terminal station A, 103: Terminal station B, 104-1,104-2: Down signal, 105-1,105-2: Up signal, 106: Down signal frame delimiter, 107: Up Signal frame delimiter, 108-1,2,3,4: Down signal slot, 109-1,2,3,4: Up signal slot, 110: Time axis.