JP3282319B2 - Mobile communication system, its radio base station, and mobile terminal - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile communication system, and more particularly to a cellular telephone system. In general, since a mobile terminal can move freely, if it goes out of the service area, that is, out of the service area, communication becomes impossible.

Therefore, the mobile terminal always determines whether or not the mobile station is within the service area by using the signal of the control channel transmitted from each radio base station. It is necessary to reduce the power.

[0003]

2. Description of the Related Art FIGS. 5 (a) and 5 (b) are illustrations of a conventional example of an out-of-service area judging method. FIG. 5 (a) is an explanatory view of a main part of a system, FIG. FIG. 7 is an example of a configuration diagram of a main part of a mobile terminal, FIG.
FIG. 9 is a configuration diagram of a main part of a processing / control unit in FIG. 7, FIG. 9 is an explanatory diagram (mobile terminal) of an out-of-service determination procedure of a conventional example, FIG.

Hereinafter, FIGS. 5 to 9 will be described. In FIG. 5A, the service area is divided into n small zone cells, and one radio base station is provided in each cell. The radio base station signal of the downlink (base station → mobile terminal) control channel of different frequencies for each cell _{(f 1, f 2 ·· f} n) ( hereinafter, abbreviated as a control signal) and a plurality of Call channel signal (
In the following, the control signal is always transmitted (see FIG. 5 (b)-(1)).

Here, the radio base station 1 comprises a processing / control unit 11, a modulation unit 12, a demodulation unit 13, a transmission unit, as shown in FIG.
14, a receiving unit 15, a frequency synthesizer 16, and the like, and a wireless base station control unit 51 for controlling the operation of a subordinate wireless base station, and a public telephone network via a mobile telephone exchange 52 connected to a public telephone network by a wired line, Mobile terminals that are not connected are connected by wireless lines.

The processing / control unit 11 has a function of monitoring and controlling communication with the mobile terminal, for example, allocating a communication channel, and the modulating unit 12 and the transmitting unit 14 modulate an input signal. The receiver 15 and the demodulator 13 convert the received signal to a predetermined frequency and level to extract the signal, and the frequency synthesizer 16 controls the processing / control unit. It has a function of generating a transmitting station-originated signal and a receiving station-originated signal corresponding to the control signal from 11 and transmitting them to the transmitting unit and the receiving unit, respectively.

On the other hand, as shown in FIG. 7, the mobile terminal 2 comprises a processing / control unit 21, a modulation unit 22, a demodulation unit 23, a transmission unit 24, a reception unit
25, frequency synthesizer 26, display unit 25, etc.
The display unit 27 has a function of displaying the result of processing by the processing / control unit 21, and the other parts have the same functions as the corresponding parts in the radio base station.

Although the processing / control unit 21 has the structure shown in FIG. 8, the operation of FIG.
A program to be executed by 1 is stored in the synthesizer control information memory 215 in the same way as the base station side, in which local oscillation frequency values required for transmitting and receiving control signals and communication signals are stored. when in the standby state is sends a control signal for receiving a control signal of frequency f ₁ to the frequency synthesizer 26.

[0009] Now, the reception section 25 in FIG. 7, at all times through the antenna, of the control signal of the frequency f ₁ ~f _n being input, frequency conversion by receiving only the control signal of frequency f ₁ Performing processing such as amplification and sending the result to the demodulation unit 23, and receiving electric field strength (RSSI ₁ ) corresponding to the reception level
To the processing / control unit 21.

The CPU 211 in the processing / control section 21b of FIG.
If the input RSSI ₁ is equal to or higher than a preset threshold value, the reception level of the frequency f ₁ is stored in a predetermined area in the RAM 213.
After storing the RSSI _1, synthesizer control information memory 215 the value of the reception local oscillation frequency to receive the signal of frequency f ₂
And added to the frequency synthesizer 26 of FIG.

Then, the corresponding signal from the receiving station is sent from the frequency synthesizer to the receiving section 25, and the
The receiving section 25 sends the RSSI _{2 of the} frequency f ₂ to the processing / control section 21, and the CPU 211 of FIG. 8 stores the RSSI ₂ in the RAM 213 if the value of the RSSI ₂ is higher than the threshold. This is called frequency f _n
Repeat until (See FIG. 5 (b)-(2) and FIG. 9 (a) -S1, S2). The reason why the subscript “b” is added to the symbol of the processing / control unit in FIG. 8 is to distinguish it from the processing / control unit of the embodiment shown in FIG.

When the CPU 211 detects that the RSSI values of the signals of the frequencies f ₁ to f _n are all below the threshold value, the CPU 211 determines that the signal is out of the service area (out of service area) and turns off the power supply of the receiving unit. Turn off and turn on timer 216 operation (
(See FIG. 9 (a) -S4, S5). When the operation of the timer is turned off in time T ₀ elapses, again, performing the out-of-service / out-of-range determination described above to turn on the receiver (see FIG. 9 (b)). However, if there is at least one RSSI having a value equal to or greater than the threshold value, it is determined that the terminal is within the service area, and the apparatus waits for reception of the signal of the highest RSSI (see FIG. 9 (a) -S3).

[0013] In addition, the determination interval of the in-range / out-of-range is often performed, for example, at intervals of several minutes when the mobile terminal is in a standby state.

[0014]

Here, the mobile terminal is:
Even at locations which can not receive the signal of frequency f ₁ ~ f _n at all, these signals sequentially received, because repeated to make a determination of the distance / out of range by comparing the time of the RSSI with the threshold value, the mobile There is a problem that the battery of the terminal has to supply power to a necessary part, resulting in non-negligible power consumption.

An object of the present invention is to reduce power consumption when a mobile terminal performs out-of-service determination.

[0016]

FIG. 1 is a block diagram showing the principle of the first to third embodiments of the present invention. In the figure, reference numeral 1 denotes a radio base station having a function of grasping the use state of a communication channel that can be used by the own station and a function of transmitting a signal for determining whether or not the mobile terminal is out of the service area. 2 is a mobile terminal,
Reference numeral 3 denotes a channel transmission function for out-of-service determination, and reference numeral 4 denotes a channel reception function for out-of-service determination.

[0017] The present invention provides another wireless base station.
A signal common to other radio base stations is transmitted on a common channel that can be used in common with the frequency and time of the line base station, and the mobile terminal performs out-of-range determination based on the reception state of the common channel.

Furthermore the present invention may contain other among the plurality of radio base stations
On a common channel that can be used in common with the frequency and time of the radio base station, a common signal is transmitted with other radio base stations ,
The mobile terminal determines whether or not it is in a state where it can communicate via the service area based on the reception state of the common signal .

[0019]

According to the present invention, a plurality of radio base stations can commonly use a frequency and a time with other radio base stations for in- range / out-of-range determination.
Provide a functional common channel. Then, the common channel is used from all the base stations by using this common channel with other radio base stations.
Send the issue . The mobile terminal performs out-of-service determination based on the reception state when receiving the common signal .

As a result, the out-of-service determination time is reduced by 1 /
n, the power consumption required for out-of-service determination is 1 / n
To decline.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In an embodiment of the present invention, a plurality of radio base stations share
As a common channel, a control channel (frequency f ₁
~ F _n ) Is not used and the frequency f _c Sphere of signal
Provided for outside judgment. And from all wireless base stations
This frequency f _c Send The mobile terminal has a frequency f _c of
RSSI when receiving a signal _c Is below the threshold
If it is, it is determined that it is out of service area. Note that the communication channel (the communication channel
Channel + control channel)
Sometimes, there is no communication channel available for mobile terminals,
The corresponding wireless base station stops sending the out-of-service determination signal.
You. As a result, the mobile terminal has the frequency f _c Receive the signal of
RSSI _c  Is below the threshold value and judges out of service area
And the receiver power is turned off.
Power consumption without unnecessary communication with wireless base stations
Reduce. If the mobile terminal is within range,
It is better to set up the line via a wireless base station with good line conditions
Therefore, the RSSI ₁ ~ RSSI _n Seeking
Of the RSSIs above the threshold,
Standby state for the wireless base station.

FIG . 2 is an explanatory diagram of out-of-service determination of the first and second embodiments of the present invention, and FIG. 3 is a configuration diagram (a processing / control unit and the like) of a main part of the third embodiment of the present invention. ) Indicates a wireless base station.
FIG. 4 (b) is a mobile terminal, and FIG. 4 is an explanatory diagram (mobile terminal) of the first to third out-of-service determination procedures of the present invention.

Here, the same reference numerals indicate the same objects throughout the drawings. Although the main configuration of the radio base station and the mobile terminal is almost the same as in FIGS. 6 and 7, the processing / control unit and the transmission unit in FIG. 3 are different between the present invention and the conventional example. To distinguish them. Furthermore, the ROM 21 in FIG.
A program for causing the CPU 211 to operate as shown in FIG. 4 is stored in 2a, and the CPU operates according to this program.

Hereinafter, the present invention will be described with reference to FIGS. 2 to 4, but the parts described in detail above will be described briefly.
The part of the present invention will be described in detail. First, FIGS. 2 and 3
As shown in (1), one radio base station is provided for each of the n cells, and the processing / control unit 11a includes all communication channels (control channel + communication channel) and out-of-service determination managed by the own station. A channel usage memory 114 for storing the latest usage status of the service channel, a display unit (not shown) for displaying this status, and an _fc transmission control unit 31 are provided.

Further, the transmission unit 14a, provided f _c oscillator 32 for generating a signal for the oscillator group 141 and out of service / close determination for generating a signal of a communication channel, but the latter oscillator using all communication channels except when in, is sending a signal at the frequency f _c.

[0026] In addition, the stopping of the transmission of the signal of frequency f _c is, CP
When U 111 detects that the usage status stored in the channel usage memory 114 is in a state of no margin, f _c
This is performed by transmitting a control signal from the transmission control section 31 to turn off the gate 33 provided on the output side of the _fc oscillator.

On the other hand, a processing / control unit provided in the mobile terminal
CPU 211 in 21a reads the value of the reception local oscillation frequency for receiving a signal of a frequency f _c from f _c control information memory 41, the frequency synthesizer 26 of Figure 7 this value via the interface INF 214 Send out. Accordingly, the reception section 25 that is turned on is sent to the processing and control unit 21a of the reception field strength (RRSSI _c) corresponding to the received level by receiving a signal of a frequency f _c which is input via the antenna (See FIG. 4-S1, S2).

Then, the CPU 211 shown in FIG.
Threshold to be pre-set and RSSI _c (e.g., stored in the RAM 213) compares the magnitude of the comparison result RSSI _c <
If it is the threshold value, it is determined to be out of service area, the determination result is displayed on the display unit 27 of FIG. 7, the power of the receiving unit is turned off again, and the timer is turned on (FIG. 4-S5, S6). See).

However, if RSSI _c > threshold, the CPU
211 determines that it is within the service area, and attempts to sequentially receive n waves as in the conventional example (see FIG. 4-S3). That is, CPU 211
Retrieves the f ₁ control information for receiving a signal of a frequency f ₁ from the synthesizer control information memory 215, since the delivery to the frequency synthesizer 26 of Figure 7, the frequency synthesizer
26 sends the synthesizer output, such as signal frequency f ₁ can be received as a reception local oscillation signal.

Therefore, the receiving unit 26 receives the RSSI ₁ obtained by receiving the signal of the frequency f ₁ input via the antenna, and converts the RSSI ₁ obtained in FIG.
To the processing / control unit 21a. The CPU 211 compares the RSSI ₁ with the set threshold value and stores the result in the RAM 213 if the former is larger than the latter. This is repeated, and when the signal of the frequency f _n is completed, it is determined that the signal is out of the service area if the RSSI of the n-wave is smaller than the threshold value, but the service area is determined if at least one RSSI is larger than the threshold value. And enters a standby state (see FIG. 4-S4).

[0031] Note that when the wireless base station a call channel is saturated, so stops sending the signal of the frequency f _c as described above, in the mobile terminal during the waiting time you are in the radio zone becomes out of range display Since the power of the receiving unit is turned off to prevent useless communication with the base station in which the communication channel is in a saturated state, the saturated state may be quickly resolved.

[0032]

As described above in detail, according to the present invention, there is an effect that it is possible to reduce the power consumption when the mobile terminal performs the out-of-service determination.

[Brief description of the drawings]

FIG. 1 is a principle configuration diagram of first to third aspects of the present invention.

FIG. 2 is an explanatory diagram of out-of-service area determination according to the first and second embodiments of the present invention.

FIGS. 3 (a) and 3 (b) are main part configuration diagrams (processing / control units) of a third embodiment of the present invention, where (a) is a case of a radio base station and (b) is a case of a mobile terminal;

FIG. 4 is an explanatory diagram (mobile terminal) of a first to third out-of-service determination procedures of the present invention.

5A and 5B are explanatory diagrams of an out-of-service area determination method according to a conventional example, wherein FIG. 5A is an explanatory diagram of a main part of a system, and FIG.

FIG. 6 is an example of a configuration diagram of a main part of a wireless base station.

FIG. 7 is an example of a configuration diagram of a main part of a mobile terminal.

FIG. 8 is a main part configuration diagram of a processing / control unit in FIG. 7;

FIG. 9 is an explanatory diagram (mobile terminal) of an out-of-service area determination procedure of a conventional example.
(a) is a flowchart, (b) is an explanatory diagram of a timer operation.

[Explanation of symbols]

1 wireless base station 2 mobile terminal 3 out-of-service channel transmission function 4 out-of-service channel reception function

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04Q ^7/ 00-7/38 H04B ⁷ /24-7/26

Claims (7)

(57) [Claims] 1. A mobile communication system in which a mobile terminal communicates via a service area composed of a plurality of radio base station radio zones, wherein the radio base station communicates with other radio base stations in frequency and time.
Is a common channel that can be used in common with other wireless base stations.
A mobile communication system transmitting a common signal , wherein the mobile terminal performs out-of-service determination based on a reception state of the common signal . 2. A mobile communication system in which a mobile terminal communicates via a service area composed of a plurality of radio base station radio zones, wherein the radio base station communicates with another radio base station in frequency and time.
Is a common channel that can be used in common with other wireless base stations.
It transmits a common signal, the mobile terminal, the mobile communication system characterized in that to determine whether a communicable state through the service area by the reception state of said common signal. 3. A mobile terminal of a mobile communication system that communicates through a service area composed of wireless zones of a plurality of radio base stations, wherein a frequency and a time can be commonly used by a plurality of radio base stations.
Transmitted from the plurality of radio base stations via a simple common channel.
Receiving a common signal at the plurality of radio base stations to be transmitted
Receiving means and the mobile terminal; and a service area determination means for performing a service area judged by the reception state of said common signals received in said receiving means. 4. A mobile terminal of a mobile communication system that communicates via a service area composed of a plurality of radio base station radio zones, wherein a plurality of radio base stations can commonly use frequency and time.
Transmitted from the plurality of radio base stations via a simple common channel.
Receiving a common signal at the plurality of radio base stations to be transmitted
Mobile terminal to a receiving means, characterized in that it has a discriminating means for discriminating whether or not the communicable state through the service area by the reception state of said common signals received in said receiving means. 5. A radio base station constituting an individual radio zone in a service area of a mobile communication system in which a mobile terminal wirelessly communicates, wherein frequency and time can be commonly used with other radio base stations.
A wireless base station comprising: a transmitting unit that transmits a signal common to another wireless base station for a mobile terminal serving as a communication partner to perform out-of-service determination via a common channel . 6. A radio base station constituting an individual radio zone in a service area of a mobile communication system in which a mobile terminal communicates wirelessly, wherein frequency and time can be commonly used with other radio base stations.
Via a common channel, sending mobile terminal as the communication partner to transmit for determining whether a communicable state through a service area, a common signal with another wireless base station
Radio base station; and a signal means. 7. The radio base station according to claim 5, wherein
The transmitting means may be used when the communication channel is unavailable.
A wireless base station for stopping transmission of a common signal .