JPH0984093A - Mobile terminal equipment for small cell mobile communication system and power supply control method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the current consumption of a battery by controlling power supply for a radio section at high speed moving time thereby interrupting the power supply for a prescribed time in a mobile terminal equipment for a mobile communication system constituted by small-sized cell system radio zones. SOLUTION: A control section 60 of a mobile terminal equipment 10 counts the number of times of zone roaming for a prescribed time with an output of a reception electric field detection circuit 21 of a radio section 20 and discriminates that the mobile terminal equipment is moving at a high speed when the count is in excess of a preset number set in a ROM 62. A power supply control section 30 is controlled to interrupt a power supply from a battery 40 to the radio section for a prescribed time designated by a timer circuit section 7 to save the battery power.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile terminal device which is used in a mobile communication system of a small cell type wireless zone configuration and which is supplied with power from a battery and a power control method thereof.

[0002]

2. Description of the Related Art Conventionally, the radio zone of each base station of a mobile communication system has generally been a large zone with a radius of several kilometers or more.
Small zones (small cells) of m or less have also been put to practical use. As described above, when the size of the wireless zone changes from the large zone to the small zone or the small cell system, the ratio of the time for searching for a new zone (cell) to the moving speed of the mobile terminal device is the entire waiting state. Grows with time. This is because the smaller the zone with respect to the moving speed (constant speed) of a moving body such as an automobile or a train, the shorter the time for staying in one zone. For this reason, even though the wireless output of the wireless unit was reduced for small cells to reduce the current consumption, the detection operation time for searching the zone to wait for during high-speed movement increased,
For this reason, the current consumption increases and the battery usage time is shortened.

[0003]

In a conventional mobile terminal device for a small cell system, when moving at a high speed, the time staying in one zone (cell) is shortened and the current is wasted despite being unsuitable for communication. Consumes less and shortens the battery usage time.

Therefore, an object of the present invention is to provide a mobile terminal device and a power supply control method thereof for controlling the power supply of a radio unit according to the moving speed in a small cell type mobile communication system to reduce the current consumption. Especially.

[0005]

A mobile terminal device of the present invention moves in a service area of a small cell type mobile communication system in which a plurality of base stations are arranged in a service area and each constitutes a wireless zone of a small cell. In a mobile terminal device that wirelessly communicates with a base station corresponding to a wireless zone in which the self exists, a wireless unit that wirelessly transmits and receives a signal to and from the base station and that detects a received electric field strength of a received signal; A power control unit that controls the power supply from a battery to the unit, and the movement between the wireless zones is recognized by a change in the received electric field strength of the received signal from the base station detected by the wireless unit, and within a predetermined unit time. If the number of times of movement between the wireless zones exceeds the previously stored allowable number of movements, it is determined that the vehicle is moving at a speed unsuitable for communication, and the power control unit is controlled to control the wireless unit. And a control unit for a predetermined time stopping the power supply is specified in advance.

A power supply control method for a mobile terminal device according to the present invention is
A mobile terminal that moves within the service area of a small cell type mobile communication system in which a plurality of base stations are arranged in the service area and each constitutes a wireless zone of a small cell, and wirelessly communicates with a base station corresponding to a wireless zone in which the self exists. In a power supply control method for an apparatus, the allowable number of times of movement between wireless zones within a predetermined unit time and a fixed time during which a wireless connection operation with the base station is stopped are stored in advance, and a received signal from the base station is stored. The movement between the wireless zones is recognized by the change in the received electric field strength, and when the number of movements between the wireless zones within a predetermined unit time exceeds the allowable number of movements, it is determined that the vehicle is moving at a speed unsuitable for communication, and the base The power consumption of the battery is reduced by stopping the power supply to the wireless unit that wirelessly transmits and receives signals to and from the station for the fixed period of time to stop the unnecessary wireless connection operation. Reduction carried out.

[0007]

FIG. 1 is a block diagram showing an embodiment of a mobile terminal device of the present invention. In a mobile communication system, a simple portable telephone system (PHS) having a zone structure as shown in FIG. 3 is used. Is used. In FIG. 1, the mobile terminal device 10 wirelessly transmits and receives signals to and from the base station via the antenna 22 by radio for standby and communication, and detects the electric field strength of the received radio wave with the built-in reception electric field detection circuit 21. Part 20, ROM 62, RAM 63
A control unit 6 that has a CPU 61 that performs various processes based on programs and data stored in
0, a display unit 50 that visually displays data, a timer circuit unit 70 that measures elapsed time, a battery (battery) 40 that is a power supply source, and a power supply from the battery 40 to each unit in the device including the wireless unit 20. Power supply control unit 30 for controlling the supply / stop of supply of the power supply.

FIG. 2 is a flowchart showing a power supply control method when moving between zones of the mobile terminal control device of the present invention.

FIG. 3 is a diagram showing a zone configuration example of a mobile communication system to which the present invention is applied. Multiple base stations 1, 2,
Reference numerals 3 and 4 have zones 1, 2, 3 and 4 each having a radius of about 100 m as wireless zones of the small cell system, and the base stations 1 to 4 are partially overlapped with each other.
Is arranged. When the mobile terminal device 10 moves from point A to point B, the staying zone changes from zone 1 to zone 3 and zone 4.

Next, the operation of the mobile terminal device of the present invention will be described with reference to FIGS.

When the mobile terminal device 10 moves in a standby mode, the fluctuation time of the received electric field level changes according to the moving speed. When the control unit 60 detects from the detection result of the reception electric field detection circuit 21 of the wireless unit 20 that the reception electric field level is not suitable for standby, it recognizes that the zone has moved (Yes in step S1 of FIG. 2) and searches for a new zone. In order to do so, the wireless unit 20 is controlled to perform a zone search for a reception electric field level that can stand by by changing from intermittent reception operation to continuous reception operation. As the moving speed becomes faster, the interval of this operation becomes shorter and the ratio of the zone search time to the waiting time becomes larger. Unit time for moving speed judgment x
The allowable number of movements to
By registering in step 2, if the actual number of movements exceeds this y, it is determined that the high-speed movement is not suitable for communication (Yes in step S2) and the power supply of the terminal device or the power supply of the wireless unit for a certain period of time. Control to turn off. This power supply control is performed as follows. The control unit 60 compares the information from the wireless unit 20 with the information in the ROM 62, and when detecting that the actual number of movements exceeds the allowable number of movements y, controls the power supply control unit 30 to control the wireless unit 20 and the display unit. Power supply to other unnecessary parts such as 50 is stopped (step S3), and at the same time, the timer circuit unit 70 is activated to perform timed time measurement for a predetermined fixed time (for example, 1 minute to 10 minutes) (step S3). S4). When the timer circuit unit 70 times out (Yes in step S5), the control unit 60 controls the power supply control unit 30 to restart the power supply by the battery 40 to the wireless unit 20 and other parts (step S5).
6).

The values of the unit time x and the allowable number of movements y can be determined as follows. Here, it is assumed that a is the time until the search standby in the new zone due to the zone movement is entered. Also, the time for moving to a new zone and performing handover during communication is set to b. When the time staying in the zone is c, it can be determined as follows. (1) Calculation example for determining that standby is possible The ratio d for determining standby is the zone search time a with respect to the time c when the vehicle stays in the zone and waits.
The ratio of d = a / c × 100 (%) When this value d is equal to or less than e%, it is determined to be suitable for standby. Assuming a wireless zone with a zone diameter of 200 m, if e is 10%, 10 = a / c × 10
It becomes 0 and c = 10a. If the search time for waiting for a is 2 seconds, c will be 20 seconds or more. The moving speed at this time can be calculated as 36 km / h. (2) Calculation example for determining that a good call can be made The ratio f for determining that a good call can be made is determined by the time b of zone search and reconnection during handover with respect to the time when the call remains in the zone and can be called. The ratio. f = b / c × 100 (%) When this value f is g% or less, it is determined that good communication can be performed. Assuming a wireless zone with a zone diameter of 200 m, if g is 10%, then 10 = b / c × 10
It becomes 0 and c = 10b. If the time for zone search and reconnection for handover in b is 2 seconds, c is 2
It will be 0 seconds or more. The moving speed at this time is 36 km / h
/ H can be calculated. Also, the value of c at this time varies depending on the handover method. For example, the time varies depending on the recalling type handover or the direct handover with a switching instruction.

By such calculation, the moving speed can be determined by the size of the zone, the zone selection time for waiting, and the handover time during communication. This is a parameter for determining the values of x and y, and can be set as a time (x) for a plurality of times (y) for determining this condition. In this mobile communication system, for example, 36 km / h
When it is considered that high speed (10 m / sec) or more is not suitable for communication, x and y can be set as follows. Zone diameter 2
If 00m and y is 10, then x = zone diameter × moving frequency (y) / moving speed = 200 × 10/10 = 200
(Seconds). That is, the unit time x is 200 seconds,
The actual number of movements within this time is 10
If it exceeds the number of times, it is determined that high-speed movement not suitable for communication is being performed.

[0014]

According to the present invention, when the mobile terminal device moves at a certain speed or more, the wireless zone (base station) is frequently changed in the small cell system and sufficient call quality cannot be secured. In order to reduce the meaningless zone selection search time, the useless battery consumption can be reduced by entering the battery saving state in which the wireless unit is powered off.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a mobile terminal device of the present invention.

FIG. 2 is a flowchart showing a power supply control method when moving between zones of a mobile terminal device of the present invention.

FIG. 3 is a diagram showing a wireless zone configuration example of a mobile communication system to which the present invention is applied.

[Explanation of symbols]

 10 mobile terminal device 20 wireless unit 21 received electric field detection circuit 30 power supply control unit 40 battery 60 control unit 70 timer circuit unit

Claims (2)

[Claims] 1. A base station corresponding to a radio zone in which a self exists, which moves in the service area of a small cell type mobile communication system in which a plurality of base stations are arranged in the service area and each constitutes a radio zone of a small cell. In a mobile terminal device that performs wireless communication, a wireless unit that wirelessly transmits and receives a signal to and from the base station and that detects a received electric field strength of a received signal, and a power supply control that controls power supply from a battery to the wireless unit. Section, the movement between the wireless zones is recognized by the change in the received electric field strength of the received signal from the base station detected by the wireless section, and the number of movements between the wireless zones within a predetermined unit time is stored in advance. If the number of times of movement is exceeded, it is determined that the vehicle is moving at a speed unsuitable for communication, and the power supply control unit is controlled to supply power to the wireless unit at a predetermined constant level. A mobile terminal device, comprising: a control unit for stopping the time. 2. A base station corresponding to a radio zone in which the mobile station itself exists and which moves within the service area of a small cell type mobile communication system in which a plurality of base stations are arranged in the service area and each constitutes a radio zone of a small cell. In a power supply control method for a mobile terminal device that performs wireless communication, in advance, an allowable number of times of movement between wireless zones within a predetermined unit time and a fixed time for stopping a wireless connection operation with the base station are stored, Recognizing the movement between the wireless zones by the change in the received electric field strength of the received signal from the station, and when the number of movements between the wireless zones within a predetermined unit time exceeds the allowable number of movements, it is moving at a speed unsuitable for communication. By determining and stopping the power supply to the wireless unit that wirelessly transmits and receives signals to and from the base station for the certain period of time to stop the unnecessary wireless connection operation. Power supply control method for a mobile terminal device which is characterized in that the current consumption reduction of the battery.