JPH04207534A - Zone discrimination method - Google Patents

Abstract

PURPOSE:To accurately grasp the state that a mobile station is not moving across zones by allowing a base station to implement transmission power control and allowing the mobile station to measure and compare a reception electric field level of the base station during communication and a reception electric field level of peripheral base stations. CONSTITUTION:A mobile station 101 measures a reception electric field level of a base station 102 during communication and a reception electric field level of peripheral zones and sends the result of measurement to the base station as transmission information and the base station 102 during communication obtains correction information from an electric field level of a radio channel during communication based on the transmission information from the mobile station 101 and the base station 102 sends the correction information to the mobile station 101. The mobile station 101 receiving the correction information corrects the reception electric field level of the radio channel during communication and compares the electric field level after the correction with the reception electric field level of the peripheral zone and moves across zones when the reception electric field level of the peripheral zone is higher but does not move across zone when the reception electric field level of the peripheral zone is higher. Thus, a resident zone of the mobile station is accurately discriminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a zone determination method, and particularly to a zone determination method for determining the zone in which a mobile station resides in a mobile communication system having a small zone configuration.

[Conventional technology]

A typical example of a mobile communication system with a small zone configuration is a car telephone system. In the car telephone system, the purpose of reducing the power consumption of radio equipment and reducing co-channel interference is to measure the received electric field level of the opposing radio equipment (by measuring the receiving electric field level of the opposite radio equipment). A method is adopted to control the

Specifically, if the received electric field level measurement result from the base station or the opposing mobile station is a high value, control is performed to lower the transmission power to the mobile station within a range that satisfies a predetermined transmission quality. . On the other hand, if the received electric field Ll\\ measurement result is a low value, the base station performs control to increase the transmission power of the mobile station within a range that does not exceed the maximum transmission power.

In addition to transmission power control, mobile communication systems using time division multiple access (TDMA) speed up zone determination and
This has the effect of distributing the load on the base station control equipment. Therefore, it is relatively easy to detect zone transition using a mobile station. The second zone transition detection measures the received electric field level of the wireless channel that the mobile station is communicating with and the received electric field level of the surrounding zone, and compares the received electric field level of the surrounding zone.If the received electric field level of the surrounding zone is higher, the mobile station performs zone transition. It will be confirmed that it happened.

[Problem to be solved by the invention] However, in a conventional system in which transmission power control is performed on the base station side, when the mobile station uses the L8 lane method, it is difficult to control the received electric field level of the mobile station or the surrounding zone. When measuring the frequency, it is desirable to measure the frequency that is transmitted from the base station at a constant power. to measure the level of the radio channel being transmitted to the mobile station. However, if the base station is controlling the transmission power of the wireless channel during communication (in contrast, if the mobile station is transmitting at maximum output when performing pulse measurements (compared to As a result, the received electric field level in the surrounding zone is higher than that in the surrounding zone, causing the mobile station to judge that it has changed zones even though the mobile station has not moved between zones, causing the problem that the mobile station will switch zones. there were.

The present invention has been developed in view of the above points, and a base station performs transmission power control, and a mobile station measures and compares the received electric field level of the base station in communication with the received electric field level of surrounding base stations, It is an object of the present invention to provide a zone determination method for a TDMA mobile communication system that can accurately grasp the situation in which a mobile station is not performing zone migration.

[Means to solve the problem]

FIG. 1 shows a diagram explaining the principle of the present invention. A mobile communication system that covers a service area with multiple base stations, communicates between mobile stations and base stations using a time division multiple access method, and controls base station transmission power according to the received electric field level at the mobile station. In the zone determination method, the mobile station uses measuring means to measure the first received electric field level of the zone in which it is communicating and the second received electric field level of the surrounding zone, and sends the measurement results of the first received electric field level to the base station. Step 11), the base station transmits information regarding the transmission power to the mobile station based on the received first received electric field level (Step 13), and the mobile station corrects it based on the received information regarding the transmission power (Step 13). Step 1
5) The determination means compares the received electric field level of the wireless channel during communication with the second received electric field level to determine the zone (step 17). In addition, when the base station transmits correction information for the received electric field level to the mobile station, and the mobile station compares the received electric field levels to determine the zone in which it is located, the mobile station uses the received correction information to determine whether the mobile station is communicating. Correct the received electric field level of the wireless channel.

(Operation) The present invention measures the received electric field level in the zone of the base station with which the mobile station is communicating and the received electric field level in the surrounding zones, and transmits the measurement results to the base station as transmission information. Based on the transmission information from the mobile station, correction information is determined from the electric field level of the wireless channel during communication, and the base station further transmits this correction information to the mobile station.The mobile station that receives this correction information is in communication. Correct the received electric field level of the wireless channel, compare the corrected electric field level with the received electric field level of the surrounding zone, and if the received electric field level of the surrounding zone is higher, perform a zone transition, or if it is lower, perform a zone transition. This determines the exact zone in which the mobile station is located.

〔Example〕

FIG. 2 is a diagram showing the system configuration of a general car telephone system. In the figure, mobile station 101 is communicating with base station +02. In addition, base stations 103 to 10
8 is adjacent to the base station 102, and base stations 103 to +0
At least one common control channel used within each zone is set in 8. These channels are always transmitting at the maximum output that each base station can set.

FIG. 3 shows the configuration of a mobile station according to an embodiment of the present invention. The mobile station 101 includes a modulation circuit 201, a demodulation circuit 202, a synthesizer 203, a reception level measurement circuit 204, a timing generation circuit 205, an encoding circuit 206, a control circuit 207, and a decoding circuit 208.

The reception level measurement circuit 204 is a timing generation circuit 205
(Based on this, the control circuit 20
This circuit switches the frequency of the frequency synthesizer 203 specified from 7 to measure the reception level. A timing generation circuit 205 is a circuit that generates frame timing. The encoding circuit 206 is a circuit that multiplexes the information signal from the base station 102 and the control signal from the control circuit 207 into a TDMA frame, and further encodes the signal for transmission over the radio section. The mobile station 101 is controlled by the signal from the level measurement circuit 204 and the decoded signal from the decoding circuit 208. Decoding circuit 2
08 decodes the received signal, separates the received signal into a control signal and an information signal, and sends the control signal to the control circuit 207 and the information signal to the base station 102.

FIG. 4 shows an explanatory diagram of a measurement operation in a mobile station according to an embodiment of the present invention. In the figure, (A) shows the reception signal of mobile station +01, and (B) shows the reception frequency of mobile station 101. Frame F1 in (B) is 30a to 30 in (A) in the same figure.
The 3° frame F2, which is the frequency of the radio channel used for communication at the timing f, and the frame F7 are the frequencies of the common control channels of the respective peripheral base stations 103 to 108.

When the mobile station +01 starts communication, the base station 102 selects frequencies F2 to F, respectively, from among the common control channel frequencies used by the surrounding base stations 103 to 108.
7 to the mobile station 101. The mobile station 101 uses nearby base stations 103 to 10 during slots not used for communication.
Switch to the frequency notified from 8 and press 3 in the same figure (A).
Signals from the surrounding zones are received at timings 1a to 31f, and the received electric field levels of the surrounding base stations 103 to 108 are sequentially measured.

FIG. 5 shows an explanatory diagram of level measurement results and correction operations in a mobile station according to an embodiment of the present invention. In the figure, a level 401 indicated by a broken line indicates the received electric field level of the base station 102 during communication, and levels 403 to 408 indicate the level of the received electric field of the base station 102 in communication.
08 received electric field level and level correction value 409 are base station 1
You will be notified from 02. The level 402 indicates the received electric field level of the base station 102 during communication after correction.

FIG. 6 shows the sequence of operations of an embodiment of the present invention.

The operation of this embodiment will be explained with reference to the sequence diagram shown in FIG.

The mobile station 10
1 measures the received electric field level using the received level measuring circuit 204 and stores it in the memory in the control circuit 207 (step 5).
0 co). Furthermore, the mobile station 101 also notifies the base station 102 of the measured received electric field level using the control channel (
Step 502).

The base station 102 compares the received electric field level information transmitted from the mobile station 101 with a predetermined level of the base station 102, and if the received electric field level information from the mobile station 101 is higher than the predetermined level of the base station 102, the base station The station 102 then lowers the transmission power within a range that satisfies a predetermined transmission quality, and uses that value as the transmission power setting value. Furthermore, if the received electric field level information from the mobile station 101 is lower than the predetermined level of the base station 102, the transmission power is increased within a range that does not exceed the maximum transmission power, and that value is set as the transmission power setting value (step 503 )
. Further, the maximum transmit power of the base station 102 and step 50
Find the difference between the transmission power settings set in step 3 (step 50).
5) The base station 102 notifies the mobile station 101 of this as a correction value (step 506).

As shown in FIG. 4, the mobile station 101 receives peripheral base stations 103 to 103 in frames F2 to F7 during TDMA time slots.
The frequency of the control channel 108 is switched to the frequency of the control channel 108, and the received electric field levels of the surrounding base stations 103 to +08 are measured. Further, as shown in FIG. 5, the received electric field level 401 of the channel in communication is corrected by a correction value 409 from the base station 102, and the received electric field level 401 of the base station 102 after correction is
02 (step 507).

In FIG. 5, the received electric field level 404 of the base station 104 is the highest among the received electric field levels of neighboring base stations with respect to the mobile station 101. The reception electric field level 404 of this base station 104 and the reception electric field of the base station 102 after correction /\40
2 (step 509). At this time, base station 1
If the received electric field level 402 of 02 is higher than the received electric field level 404 of the surrounding base station 104, the mobile station 101 determines that the zone transition is not occurring. Furthermore, the received electric field level 402 of the base station 102 is the received electric field level 4 of the surrounding base station 104.
If it is lower than 04, the mobile station 101 determines that it is a zone transition (step 511).

In FIG. 5, before the transmission power of the base station 102 is corrected, the mobile station 1
An example is shown in which the received electric field level 404 of the surrounding base station 104 is higher than the received electric field level of the base station 104 with which the base station 102 is communicating, and after correction, the received electric field level 402 of the base station 102 with which the communication is being performed is higher. ing. In this way, the mobile station 101 that is communicating the received electric field level correction value 409 from the base station +01
By notifying the mobile station 101, the mobile station 101 can make an accurate zone transition determination even if the base station +02 is under transmission power control.

That is, when the mobile station 101 is not notified of the correction value of the transmission power at the base station 102 due to transmission power control, the base station 102 in communication uses 401 in FIG. 5 as its own station level. determines that 404, which is higher than 401, is the destination zone and performs zone switching. On the other hand, if the present invention is used, the received electric field level of the base station 102 during communication is set to 402 after correction, so the received electric field levels of the other base stations 103 to 108 are lower than 401. Station 101 does not perform zone switching.

Note that in the above example, the base station 102 notifies the mobile station 101 of the correction value only when the transmission power is changed, or the base station 102 constantly sends the correction value to the mobile station 101 when there is no other control signal. It is possible to improve the reliability of the control signal by using a method of notifying the correction value or a method of providing a dedicated control channel to constantly notify the correction value.
More reliable control can be performed.

Further, in the above sequence, in the processing of steps 505 and 506, a value smaller than the actual difference between the maximum transmission power and the transmission power setting value or a value larger than the actual value is notified to the mobile station 101 as a correction value. Suburbanization is also possible. When the base station 102 notifies the mobile station 101 of a small value, the mobile station 101 makes a zone transition determination before reaching the zone boundary level. This has the effect of dispersing 101 to the surrounding zone. For example, if traffic is concentrated in the zone of the base station 102 where the mobile station 101 is located, and if the received electric field level of the surrounding base station 104 is higher than other surrounding base stations, the mobile station 101 Zone transition to zone 104.

On the other hand, if the base station 102 notifies the mobile station 101 of a large value, zone transition is not determined even if the zone boundary is crossed to a certain extent, so there is a lot of traffic in the surrounding area.
If the traffic in your own area is low, surrounding base station 1
Channel switching from 03 to 108 can be suppressed.

〔Effect of the invention〕

According to the present invention, when the base station performs transmission power control, if the level is measured, the mobile station will receive a lower signal than when transmitting at maximum output, or the base station may have to adjust the correction value. By notifying the mobile station, accurate determination of zone transition can be made even if the base station is controlling transmission power. Furthermore, by directly manipulating the correction value of the received electric field level that is notified to the mobile station, it is possible to reduce the call loss rate by avoiding the traffic distribution in the area or from concentrating on a specific zone. Extremely useful.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the principle of the present invention, Fig. 2 is a system configuration diagram of a general car telephone system, Fig. 3 is a configuration diagram of a mobile station according to an embodiment of the present invention, and Fig. 4 is a diagram illustrating the configuration of a mobile station according to an embodiment of the present invention. FIG. 5 is an explanatory diagram of the measurement operation in a mobile station according to an embodiment of the present invention. FIG. FIG. 3 is a diagram illustrating an example sequence. 101...Mobile station, 102~+08*Base station, 201*
...Modulation circuit, 202--Demodulation circuit, 203-Non-seizer, 204...Reception electric field level measurement circuit, 205
・・Timing generation circuit, 206 ・・Encoding circuit, 20
7. Control circuit, 208. Decoding circuit. Patent Applicant: Nippon Telegraph and Telephone Co., Ltd. Diagram for explaining the principles of the present invention. Figure 1. General car telephone system 1: system configuration diagram. Figure 2. Configuration diagram of a mobile station according to an embodiment of the present invention. Figure 3.

Claims (2)

[Claims] (1) Mobile where a service area is covered by multiple base stations, communication is performed between the mobile station and the base station using a time division multiple access method, and base station transmission power is controlled according to the received electric field level at the mobile station. In the communication method zone determination method, the mobile station uses a measuring means to determine the first zone of the zone in which it is communicating.
and a second received electric field level in the surrounding zone, and transmit the measurement result of the first received electric field level to the base station, and the base station adjusts the received electric field level to the first received electric field level. the mobile station transmits information regarding the transmission power to the mobile station based on the received information regarding the transmission power;
A method for determining a zone, characterized in that the zone is determined by comparing the received electric field level with the received electric field level by a determining means. (2) When the base station transmits correction information on the received electric field level to the mobile station, and when the mobile station compares the received electric field levels and determines the zone in which it is located, the mobile station receives the correction information 2. The zone determination method according to claim 1, further comprising correcting the received electric field level of the wireless channel during communication based on the .