JP7464556B2 - Wireless communication system and wireless communication device - Google Patents

Description

The present invention relates to a wireless communication system and a wireless communication device used in mobile wireless systems, and in particular to a wireless communication system and a wireless communication device that can improve convenience by allowing a call to be started if a call is made using an available slot even when a wireless call is being monitored in the wireless communication device.

Description of the Prior Art
Among wireless communication systems, there is one used in a train radio system.
In such wireless communication systems, communication between a ground station and an on-board station mounted on a train (train radio), and communication between the ground station and a maintenance terminal (wireless communication device) carried by a maintenance worker (maintenance radio) are realized using a TDMA (Time Division Multiple Access) method.

With train radio, voice calls and data communication of vehicle information are carried out between a train radio communication console, which is a ground station operated by an operations manager, and an on-board station (mobile station) installed on each train.
In addition, in the case of maintenance radio, voice communication is performed between a maintenance communication console, which is a ground station operated by a maintenance work manager, and a maintenance terminal carried by a maintenance worker, or between maintenance terminals.

The maintenance terminal also has a train radio monitoring mode and a maintenance radio mode as operation modes (reception modes). In the train radio monitoring mode, the maintenance terminal performs an operation of monitoring (eavesdropping on) train radio, and in the maintenance radio mode, performs voice communication with the maintenance communication console or between maintenance terminals.
The control unit of the maintenance terminal holds the operation mode set from the operation unit of the maintenance terminal, and controls each unit in accordance with the operation mode to perform appropriate operations.

The wireless communication system is equipped with a central control device, which performs line control and call control for train radio and maintenance radio to realize various types of communication.

[Mode switching process in the maintenance terminal: FIG. 6]
Here, the mode switching process in the maintenance terminal will be described with reference to Fig. 6. Fig. 6 is a flowchart showing the mode switching process in the maintenance terminal.
As shown in FIG. 6, the control unit of the maintenance terminal judges whether or not a mode switching operation has been performed from the operation unit (S31), and if not, returns to S31 and waits for an operation.

Furthermore, when a mode switching operation is performed in process S31, the control unit judges whether the switching destination mode is the train radio monitoring mode or the maintenance radio mode (S32). If the switching destination is the train radio monitoring mode, it is set to the train radio monitoring mode (S33), and if it is the maintenance radio mode, it is set to the maintenance radio mode (S34), and the process ends.
In this manner, mode switching is performed on the maintenance terminal carried by the maintenance technician.

[Operation of a conventional maintenance terminal: FIG. 7]
Next, the operation of the conventional maintenance terminal will be described with reference to Fig. 7. Fig. 7 is a flow chart showing the operation of the conventional maintenance terminal.
In a conventional wireless communication system, TDMA voice communication channels T1 and T2 are provided, with T1 being used for train radio and T2 being used for maintenance radio.

Then, as shown in FIG. 7, when the operation is started, the control unit of the maintenance terminal judges whether the currently set reception mode is the train radio monitor mode or the maintenance radio mode (S41).
If the set reception mode is the train radio monitor mode, the control unit controls the radio unit to wait for reception at T1 (S42).

The control section judges whether or not an incoming call has been received at T1 (S43), and if no incoming call has been received, the process returns to S41.
If an incoming call is received in process S43, the control unit performs train radio monitoring (S44), judges whether the call has ended (S45), and if the call has not ended (No), returns to process S44 to continue monitoring.
Also, if the call has been ended in process S45 (Yes), the control unit returns to process S41 and repeats the same process.

If the reception mode set in step S41 is the maintenance radio mode, the control unit waits for reception at T2 (S46), determines whether or not there has been an incoming call (S47), and returns to step S41 if there has been no incoming call.
Furthermore, if an incoming call is received in process S47, the control unit performs a maintenance radio call (S48), judges whether the call has ended (S49), and if the call has not ended (No), returns to process S48 and continues the call.
If the call is ended in process S49 (Yes), the control unit returns to process S41.
In this manner, operations are performed in the conventional maintenance terminal.

In other words, in conventional maintenance terminals, the waiting slot is switched depending on the reception mode, so when the train radio monitor mode is set, monitoring is only performed in slot T1, and even if there is an original maintenance radio call request in slot T2, it cannot be received.

[Related Technology]
Incidentally, a conventional technology for a wireless communication system is disclosed in Japanese Patent Laid-Open Publication No. 2014-155210, "Wireless Communication System" (Patent Document 1).
Japanese Patent Laid-Open No. 2003-233693 discloses monitoring of voice calls made via a base station located far from the monitor device.

JP 2014-155210 A

As mentioned above, in conventional wireless communication systems, the reception slot is determined by the reception mode set in the wireless communication device (maintenance terminal). Therefore, when the train radio monitor mode is set, even if a maintenance radio call request occurs in a different slot, it cannot be received, which is inconvenient.

Note that Patent Document 1 does not state that the wireless communication device monitors the control channel while monitoring a mobile call, and when it receives a call request on the control channel for a maintenance call that is made using an available slot on the voice channel, it stops monitoring and makes another call.

The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a wireless communication system and a wireless communication device that can improve convenience by interrupting monitoring and starting a call when a call request using an available slot is received on a control channel while a call is being monitored.

The present invention, which aims to solve the problems of the above-mentioned conventional example, is a wireless communication system having a central control station that uses a specific slot for calls in a time division multiple access communication method to make calls between ground equipment and a first wireless communication device, and uses an empty slot for calls in the communication method to make calls between the ground equipment and a second wireless communication device, and the central control station transmits a call request to the first wireless communication device or a call request to the second wireless communication device in the specific slot for control in the communication method, and the second wireless communication device monitors the specific slot for control, and when it receives a call request to the first wireless communication device, it monitors the call between the first wireless communication device and the ground equipment, and when it receives a call request to the second wireless communication device during the monitoring, it interrupts monitoring and starts the call of the call request.

The present invention is also characterized in that, in the wireless communication system, the central control station transmits a call request for a priority call with a high priority in a specific control slot, and the second wireless communication device monitors the specific control slot, and upon receiving a call request for a priority call, if monitoring is in progress, it interrupts the monitoring, and if a call with ground equipment is in progress, it interrupts the call and starts the priority call.

The present invention is also characterized in that in the above wireless communication system, when the second wireless communication device receives information in a specific control slot that the call between the ground equipment and the first wireless communication device is continuing after the call with the ground equipment is ended, the second wireless communication device resumes monitoring of the call.

The present invention is also a wireless communication device that communicates with ground equipment using an empty call slot in a time division multiple access communication method, and is characterized in that it monitors a specific slot for control in the communication method, and when it receives a call request for a call between the ground equipment and another wireless communication device in the specific slot, it monitors the call, and when it receives a call request from the ground equipment in the specific slot during the monitoring, it interrupts monitoring and starts the call for the call request.

The present invention is also characterized in that in the wireless communication device, a specific control slot is monitored, and when a call request for a priority call with a high priority is received in the specific slot, if monitoring is in progress, the monitoring is interrupted, and if a call with ground equipment is in progress, the call is interrupted and the priority call is started.

The present invention is also characterized in that when a call with ground equipment ends, if a call is still ongoing between the ground equipment and another wireless communication device, monitoring of that call is resumed.

According to the present invention, a wireless communication system having a central control station that performs a call between a ground facility and a first wireless communication device in a specific slot for calls in a time division multiple access communication method, and performs a call between a ground facility and a second wireless communication device in an empty slot for calls in the communication method, the central control station transmits a call request to the first wireless communication device or a call request to the second wireless communication device in the specific slot for control in the communication method, the second wireless communication device monitors the specific slot for control, and when it receives a call request to the first wireless communication device, it monitors the call between the first wireless communication device and the ground facility, and when it receives a call request to the second wireless communication device during the monitoring, it interrupts the monitoring and starts the call of the call request. Therefore, for example, when the second wireless communication device receives a call request addressed to itself in the specific slot for control while monitoring a wireless call of the first wireless communication device, it can perform the call of the call request, and can flexibly acquire information without being fixed by mode, which has the effect of improving convenience.

Furthermore, according to the present invention, in the wireless communication system described above, the central control station transmits a call request for a priority call with a high priority in a specific control slot, and the second wireless communication device monitors the specific control slot, and upon receiving a call request for a priority call, if monitoring is in progress, the monitoring is interrupted, and if a call with ground equipment is in progress, the call is interrupted and the wireless communication system starts the priority call. This has the effect of ensuring that a high priority call can be received even during monitoring or a call.

In addition, according to the present invention, a wireless communication device that communicates with ground equipment in an empty call slot in a time division multiple access communication method monitors a specific control slot in the communication method, and when a call request for a call between the ground equipment and another wireless communication device is received in the specific slot, the wireless communication device monitors the call, and when a call request is received from the ground equipment in the specific slot during the monitoring, the wireless communication device interrupts monitoring and starts the call of the call request. For example, when a call request addressed to the device is received in the specific control slot while monitoring a wireless call of a first wireless communication device, the call of the call request can be made, and information can be acquired flexibly without being fixed by mode, which has the effect of improving convenience.

FIG. 1 is a schematic diagram of a wireless communication system. FIG. 2 is a block diagram showing a schematic configuration of a maintenance terminal 7. FIG. 2 is an explanatory diagram showing the configuration of a TDMA slot. 10 is a flowchart showing a process of the maintenance terminal 7 in a train radio monitor mode. 13 is a flowchart showing processing for a high priority call. 13 is a flowchart showing a mode switching process in the maintenance terminal. 1 is a flowchart showing an operation of a conventional maintenance terminal.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings.
[Outline of the embodiment]
A wireless communication system according to an embodiment of the present invention (this wireless communication system) includes a central control station that realizes mobile calls between ground equipment and an on-board station as a first wireless communication device in a specific call slot in communication using TDMA, and realizes maintenance calls between ground equipment and a maintenance terminal as a second wireless communication device in an empty call slot, and the central control station transmits a mobile call call request or a maintenance call request in the specific control slot, and the maintenance terminal monitors the specific control slot and, when it receives a mobile call call request, monitors the mobile call. Even if it is during monitoring, if it receives a maintenance call request in the specific control slot, it interrupts the monitoring and starts the maintenance call. If a maintenance call occurs while monitoring a mobile call, the maintenance call can be made, improving convenience and increasing the safety of the equipment being maintained.

[Schematic configuration of this wireless communication system: Figure 1]
The schematic configuration of the present wireless communication system will be described with reference to Fig. 1. Fig. 1 is a schematic configuration diagram of the present wireless communication system. Note that, in this embodiment, the present invention will be described as being applied to a train wireless system, but is not limited to train wireless systems.

As shown in Figure 1, this wireless communication system includes a train radio communication console 1, a maintenance radio communication console 2, a central control station 3, a base station 4, an on-board station 6 mounted on a train 5, and a maintenance terminal 7 carried by a maintenance worker.
Of these, the central control station 3 and the maintenance terminal 7 are characteristic parts of this wireless communication system, and the other parts have the same configuration and operation as the conventional ones.
The ground equipment described in the claims includes the train radio communication console 1 and the maintenance radio communication console 2. The on-board station 6 corresponds to the first radio communication device described in the claims, and the maintenance terminal 7 corresponds to the second radio communication device described in the claims.

Each component of this wireless communication system will now be described.
The train radio communication console 1 is similar to a conventional one and is operated by an operations manager to carry out voice calls with an on-board station 6 mounted on a train 5 and data communication of vehicle information.
The maintenance wireless communication console 2 is operated by a maintenance work manager in the same manner as in the conventional case, and performs voice communication with a maintenance terminal 7 carried by a maintenance worker.

The central control station 3 performs line control and call control for train radio and maintenance radio, as in the conventional case, and as a feature of this wireless communication system, it transmits voice call requests via train radio and maintenance radio in a control slot so that the call requests can be received at the maintenance terminal 7 at all times.
As will be described later, each voice call is managed by assigning a unique call number.

The base station 4 is connected to the central control station 3 via a wired line, and is also connected to mobile stations 6 and a maintenance terminal 7 within the communication range via wireless lines to perform wireless communication.
The on-board station 6 is mounted on the train 5 and performs voice communication with the train radio communication console 1, as well as transmitting and receiving data such as vehicle information.

The maintenance terminal 7 is a wireless communication device carried by a maintenance worker, and is used to monitor train radio signals and make voice calls in the same manner as in the past.
In particular, the maintenance terminal 7 of this wireless communication system, as described below, constantly monitors the control slots, and when it detects a maintenance radio call request in that slot, it interrupts monitoring and starts the maintenance radio call even if it is in the process of monitoring train radio.

Furthermore, when the maintenance terminal 7 detects, in a control slot during a maintenance radio call, a priority call having a higher priority than a general train radio voice call or a maintenance radio voice call, for example, a mass call to inform of an emergency such as an earthquake alert, the maintenance radio call is terminated and the high priority call is made.
The operation of the maintenance terminal 7 will be described later.

[Configuration of the maintenance terminal 7: FIG. 2]
The configuration of the maintenance terminal 7 will be described with reference to Fig. 2. Fig. 2 is a block diagram showing a schematic configuration of the maintenance terminal 7.
As shown in FIG. 2, the maintenance terminal 7 includes a control unit 71, a wireless unit 72, a storage unit 73, a microphone 75, and a speaker 76.
In addition, an antenna 72a for performing wireless communication is connected to the wireless unit 72.
The control unit 71 starts a program stored in the storage unit 73 , controls each unit constituting the maintenance terminal 7 , and controls the operation of the entire maintenance terminal 7 .

[TDMA slot configuration: Figure 3]
Next, the configuration of the TDMA slots used in this wireless communication system will be described with reference to Fig. 3. Fig. 3 is an explanatory diagram showing the configuration of the TDMA slots.
As shown in FIG. 3, the TDMA slots of this system are composed of four slots, slot 0 to slot 3. Slot 0 and slot 1 are assigned as channels for voice communication, T1 and T2, respectively, and slot 2 and slot 3 are used as channels D1 and D2 for data communication.

In addition, the data channels in slots 2 and 3 are also used as control channels in MCA (Multi-Channel Access). A feature of this wireless communication system is that call requests for train radio voice calls and maintenance radio voice calls are transmitted through these channels.
In this wireless communication system, train radio voice calls are made using T1 and T2 in that order, and maintenance calls are made using T2 when T2 has availability.
The voice communication over train radio corresponds to the mobile communication described in the claims, and the voice communication over maintenance radio corresponds to the maintenance communication.

[Operation at the maintenance terminal]
The operation of the maintenance terminal 7 of this wireless communication system will now be described.
The maintenance terminal 7 operates in accordance with the mode set by the mode switching process shown in FIG. 6, in the same manner as in the conventional case.
In other words, when the train radio monitor mode is set, train radio is monitored, and when the maintenance radio mode is set, voice calls are made via maintenance radio, but the operation in each mode is different from the conventional one.

For example, even in the train radio monitor mode, the maintenance terminal 7 of this wireless communication system makes a maintenance call when a maintenance call is received.
In addition, when a call with a higher priority is received while monitoring train radio or making a maintenance call, the current monitoring or call is interrupted and the call with the higher priority is started. An example of a call with a higher priority is an emergency call such as an earthquake mass alert.

To achieve these operations, in this wireless communication system, slot 3 (channel D1) shown in Figure 3 is used as a control channel, and when the central control station 5 receives a call request for train radio and maintenance radio voice communication, the call request is assigned the channel to be used and transmitted using D1.
The maintenance terminal 7 constantly monitors the channel D1 to check whether a call request is received and detects whether a voice call is being made.

Furthermore, even if the control unit 71 of the maintenance terminal 7 is in the train radio monitor mode, when a maintenance radio call request is received on channel D1, the control unit 71 controls the communication to switch to a maintenance radio call.
In addition, the control unit 71 of the maintenance terminal 7 monitors channel D1 even while monitoring train radio or during a maintenance radio call, and when a call request for a high priority call is received, controls the transition to the high priority call.
These processes will be specifically described below.

[Processing in train radio monitor mode: Figure 4]
The process of the control unit 71 when the train radio monitoring mode is set in the maintenance terminal 7 will be described with reference to Fig. 4. Fig. 4 is a flowchart showing the process of the maintenance terminal 7 in the train radio monitoring mode.
As shown in FIG. 4, when the train radio monitor mode is set, the control unit 71 of the maintenance terminal 7 constantly monitors channel D1 to determine whether there is an incoming maintenance radio call, i.e., whether channel D1 contains a maintenance radio call request (S11).

If a maintenance radio call request is not included and there has been no incoming call (if No), the control unit 71 monitors D1 to determine whether there has been an incoming train radio call (whether a train radio call request is included) (S12), and if there has been no incoming train radio call (if No), it returns to processing S11 and continues monitoring channel D1.

If there is an incoming train radio signal in process S12 (Yes), the control unit 71 monitors the train radio signal (S13). The channel to be used is also specified for channel D1, and the train radio signal is monitored on channel T1, for example.

Even while monitoring the train radio, the control unit 71 monitors channel D1 to check whether there is an incoming maintenance radio call, and if there is no incoming maintenance radio call (No), it determines whether the train radio being monitored has ended (S15), and if it has not ended (No), it moves to process S13 and continues monitoring the train radio. If the train radio has ended in process S15 (Yes), it moves to process S11 and monitors channel D1.

In addition, if an incoming maintenance radio call is detected in process S11 or process S14 (Yes), the control unit 71 interrupts monitoring of the train radio, makes a maintenance radio call, and performs the maintenance radio call using the specified channel T2 (S16).

Then, the control unit 71 judges whether the maintenance radio call has ended (S17), and if not ended (No), the control unit 71 proceeds to process S16 and continues the maintenance radio call.
If the maintenance radio call ends in process S17 (Yes), the control unit 71 checks channel D1, and if the train radio is still ongoing (Yes), it proceeds to process S13 and monitors the train radio again at T1.

For example, the central control station 5 holds information (such as the call number) about the train radio call that the maintenance terminal 7 was monitoring, and when the maintenance radio call ends, it determines whether the train radio call is continuing based on the call number, and if it is continuing, it transmits the call number and the channel being used to D1, making it possible for the maintenance terminal 7 to return to monitoring the train radio. The call number is transmitted, for example, by the RICH (radio information channel) in the slot.

Also, if the train radio communication is not continuing but has ended in process S18 (No), the process returns to process S11 and monitors channel D1.
In this manner, processing in the train radio monitor mode of the maintenance terminal of this wireless communication system is carried out.

As a result, in this wireless communication system, even if the maintenance terminal 7 is set to train radio monitor mode, and even if train radio is being monitored, if a maintenance radio call is received, a maintenance radio call can be quickly established, and information about the maintenance work can be reliably transmitted to the maintenance worker.

[High Priority Call Processing: Figure 5]
Next, a process to be performed when a call with a high priority is received while a maintenance call or train radio monitoring is being performed at the maintenance terminal 7 will be described with reference to Fig. 5. Fig. 5 is a flow chart showing the process for a call with a high priority.
As shown in FIG. 5, the control unit 71 of the maintenance terminal 7 monitors the channel D1 during a maintenance call or while monitoring the train radio, and judges whether or not a call with high priority has been received (S21).

In this wireless communication system, a priority is set for each type of call, and the central control station 5 assigns a type to a call request and transmits it on the channel D1.
The control unit 71 of the maintenance terminal 7 prestores priorities corresponding to types, and checks the type attached to the call request to determine the priority.

In the process S21, if there is no incoming call with a high priority (No), the control unit 71 continues to monitor the channel D1 in the process S21.
Furthermore, if a high priority call is received in process S21 (Yes), the control unit 71 interrupts the current maintenance radio call or monitoring (train radio monitoring) (S22) and makes the high priority call (S23).

Then, the control unit 71 judges whether the call with the higher priority has ended (S24), and if the call has not ended (No), the control unit 71 returns to the process S23 and continues the call.
Furthermore, if the high priority call is ended in process S24 (if Yes), the control unit 71 checks D1 to determine whether the train radio that was being monitored before the interruption (the original train radio) is still continuing (S25), and if it is still continuing (if Yes), it switches to monitoring of that train radio (S26) and ends the process.
If the original train radio is not continuing in step S25 (No), the process ends.
In this manner, processing is performed when a high priority call is received.

Note that, here, we have taken the example of a case where a high priority call is also made as a voice call on the maintenance radio, but if there is a high priority call only on the train radio, the control unit 71 will recognize this through D1, interrupt the current train radio monitoring or maintenance call, start monitoring the train radio on channel T1, and monitor the high priority call.

[Effects of the embodiment]
This wireless communication system is equipped with a central control station 5 that realizes mobile calls between the ground equipment and the on-board station 6 in a specific call slot in communication using TDMA, and realizes maintenance calls between the ground equipment and the maintenance terminal 7 in an empty call slot, and the central control station 5 transmits a mobile call call request or a maintenance call request in the specific control slot, and a control unit 71 of the maintenance terminal 7 monitors the specific control slot, and when a mobile call call request is received, the control unit 71 monitors the specific control slot, and when a maintenance call request is received in the specific control slot even during monitoring, the monitoring of the mobile call is interrupted and a maintenance call is started, so that when a maintenance call call occurs during monitoring of a mobile call, a maintenance call that is of high importance to the maintenance worker can be made, and information can be flexibly acquired without being fixed in the mode, improving convenience and increasing the safety of the equipment to be maintained.

In addition, according to this wireless communication system, the central control station 5 transmits a call request for a call with a higher priority than a maintenance call in a specific control slot, and the control unit 71 of the maintenance terminal 7 monitors the specific control slot. When the control unit 71 receives a call request for a high priority call, if a mobile call is being monitored, the monitoring is interrupted, and if a maintenance call is being performed, the maintenance call is interrupted and the high priority call is started. This has the effect of giving priority to high priority calls such as emergency earthquake reports, ensuring the transmission of information.

In the above-described embodiment, an example has been described in which the wireless communication system is a train wireless communication system, the on-board station is a first wireless communication device, and the maintenance terminal is a second wireless communication device. However, the present invention is not limited to this, and it is sufficient that the first wireless communication device and the second wireless communication device are different, and that the second wireless communication device operates in a monitor mode in which it monitors calls made by the first wireless communication device (for example, the train wireless monitor mode described in the embodiment) and a call mode in which it makes calls (for example, the maintenance wireless mode described in the embodiment).

The present invention is suitable for a wireless communication system and a wireless communication device that, when a call request for another call using an available slot is received on a control channel while a mobile call is being monitored, can interrupt monitoring and start the other call, thereby improving convenience.

1...Train radio communication console, 2...Maintenance radio communication console, 3...Central control station, 4...Base station, 5...Train, 6...On-board station, 7...Maintenance terminal, 71...Control unit, 72...Radio unit, 72a...Antenna, 73...Memory unit, 74...Operation display unit

Claims (6)

A wireless communication system having a central control station for conducting a call between a ground facility and a first wireless communication device in a specific slot for a call in a time division multiple access communication method, and for conducting a call between the ground facility and a second wireless communication device in an empty slot for a call in the communication method,
the central control station transmits a call request to the first wireless communication device or a call request to the second wireless communication device in a specific slot for control in the communication method;
A wireless communication system characterized in that the second wireless communication device monitors the specific control slot, and when it receives a call request to the first wireless communication device, it monitors the call between the first wireless communication device and the ground equipment, and when it receives a call request to the second wireless communication device during the monitoring, it interrupts the monitoring and starts the call of the call request. The central control station transmits a call request for a high priority call in a specific slot for control,
The wireless communication system according to claim 1, characterized in that the second wireless communication device monitors the specific control slot, and when it receives a call request for the priority call, if the second wireless communication device is in the middle of monitoring, it interrupts the monitoring, and if it is in the middle of a call with the ground equipment, it interrupts the call, and starts the priority call. The wireless communication system according to claim 1 or 2, characterized in that when the second wireless communication device receives information in a specific control slot that the call between the ground equipment and the first wireless communication device is continuing after the call with the ground equipment is ended, the second wireless communication device resumes monitoring the call. A wireless communication device that communicates with ground facilities using an empty slot for communication in a time division multiple access communication method,
A wireless communication device characterized in that it monitors a specific slot for control in the communication method, and when it receives a call request for a call between ground equipment and another wireless communication device in the specific slot, it monitors the call, and when it receives a call request from the ground equipment in the specific slot during the monitoring, it interrupts the monitoring and starts the call of the call request. The wireless communication device according to claim 4, characterized in that it monitors a specific slot for control, and when it receives a call request for a priority call with a high priority in the specific slot, it interrupts the monitoring if it is in progress, interrupts the call if it is in progress with the ground equipment, and starts the priority call. The wireless communication device according to claim 4 or 5, characterized in that when the call with the ground equipment is ended, if a call between the ground equipment and the other wireless communication device is continuing, monitoring of the call is resumed.

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