JP2854967B2 - Zone judgment 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

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zone determination method, and more particularly to a zone determination method for determining a zone in which a mobile station is located in a mobile communication system having a small zone configuration.

[Conventional technology]

A typical example of a mobile communication system having a small zone configuration is an automobile telephone system. In the mobile phone system, a reception electric field level at an opposing radio is measured, and the transmission power of the radio is controlled based on the measurement result for the purpose of reducing power consumption of the radio and reducing co-channel interference. The method is adopted.

Specifically, when the electric field level measurement result received from the opposite mobile station to the base station is a high value, control is performed to reduce the transmission power to the mobile station within a range that satisfies a predetermined transmission quality. . On the other hand, when the received electric field level measurement result is a low value, the base station performs control to increase the transmission power of the mobile station within a range not exceeding the maximum transmission power.

In addition to the transmission power control, the mobile communication system based on the time division multiple access system (TDMA system) can speed up zone determination and
This has the effect of distributing the load on the control device of the base station. Therefore, the zone shift detection method by the mobile station can be relatively easily performed. In this zone shift detection, the mobile station measures the received electric field level of the wireless channel with which the mobile station is communicating and the received electric field level of the peripheral zone, compares them, and if the received electric field level of the peripheral zone is higher, the mobile station has performed the zone shift. It is confirmed that.

[Problems to be solved by the invention]

However, in a system in which conventional transmission power control is performed on the base station side, when the zone determination method by the mobile station is applied, when the mobile station measures the reception electric field level in the surrounding zone, the base station transmits the received electric field level at a constant power. It is desirable to measure the frequency at which the mobile station is constantly transmitting, for example, as represented by a common control channel, from the base station to the mobile station at the maximum power set in the zone. Is measured. However, if the base station controls the transmission power of the wireless channel during communication,
When the mobile station performs level measurement, the signal is received at a lower level than when transmitting at the maximum power.Therefore, the received electric field level in the surrounding zone becomes higher, and the mobile station moves even though it is not moving in the zone. There is a problem that the station determines that the zone has been shifted and performs zone switching.

The present invention has been made in view of the above points, the base station performs transmission power control, and the mobile station performs measurement and comparison of the reception electric field level of the base station during communication and the reception electric field level of the peripheral base station, An object of the present invention is to provide a TDMA mobile communication system zone determination method capable of accurately grasping a situation in which a mobile station is not performing zone transfer.

[Means for solving the problem]

FIG. 1 is a diagram illustrating the principle of the present invention. A mobile communication system zone that covers the service area with multiple base stations, performs communication between the mobile station and the base station using a time division multiple access system, and controls the base station transmission power according to the received electric field level at the mobile station. In the determination method, the mobile station uses the measuring means to determine the first reception electric field level of the visited zone in communication and the second reception electric field level of the surrounding zone.
, And transmits the measurement result of the first received electric field level to the base station (step 11), and the base station sends information on the transmission power to the mobile station based on the received first received electric field level. After transmitting (step 13), the mobile station corrects based on the information on the received transmission power (step 15).
The zone is determined by comparing the received electric field level of the wireless channel being communicated with the second received electric field level by the judging means (step 17). Also, when the base station transmits the received electric field level correction information to the mobile station, and the mobile station compares the received electric field level to determine the zone in which the mobile station is located, the mobile station is communicating based on the received correction information. The received electric field level of the wireless channel is corrected.

[Action]

According to the present invention, the mobile station measures the reception electric field level in the zone of the base station with which the mobile station is communicating and the reception electric field level in the peripheral zone, and transmits the measurement result to the base station as transmission information. The base station in communication obtains correction information from the electric field level of the wireless channel in communication based on the transmission information from the mobile station, and the base station transmits the correction information to the mobile station. The mobile station that has received the correction information corrects the received electric field level of the wireless channel in communication, compares the corrected electric field level with the received electric field level of the peripheral zone, and if the received electric field level of the peripheral zone is higher, the zone is higher. Perform the transition, but do not perform the zone transition if it is low. Thereby, the accurate zone in which the mobile station is located is determined.

〔Example〕

FIG. 2 is a diagram showing a system configuration in a general car telephone system. In the figure, a mobile station 101 is communicating with a base station 102. The base stations 103 to 108 are adjacent to the base station 102, and each of the base stations 103 to 108 has at least one common control channel used in a zone. These channels always transmit at the maximum power that can be set at each base station.

FIG. 3 shows the configuration of a mobile station according to one embodiment of the present invention. The mobile station 101 includes a modulation circuit 201, a demodulation circuit 202, and a synthesizer 20.
3, reception level measurement circuit 204, timing generation circuit 205,
It comprises an encoding circuit 206, a control circuit 207, and a decoding circuit 208.

The reception level measurement circuit 204 is a circuit that switches the frequency of the frequency synthesizer 203 specified by the control circuit 207 based on the frame timing from the timing generation circuit 205 and measures the reception level. Timing generation circuit
205 is a circuit for generating a frame timing. The encoding circuit 206 is a circuit that multiplexes an information signal from the base station 102 and a control signal from the control circuit 207 into a TDMA frame, and further encodes the signal for transmission in a wireless section. The control circuit 207 controls the mobile station 101 based on a signal from the reception level measurement circuit 204 and a decoded signal from the decoding circuit 208. The decoding circuit 208 decodes the received signal, separates the received signal into a control signal and an information signal, sends the control signal to the control circuit 207, and sends the information signal to the base station 102.

FIG. 4 is an explanatory diagram of a measurement operation in a mobile station according to one embodiment of the present invention. In the figure, (A) shows the reception signal of the mobile station 101, and (B) shows the reception frequency of the mobile station 101.
The frame F1 in (B) is the frequency of the wireless channel used for communication at the timings 30a to 30f in FIG.
Frames F2 to F7 correspond to respective peripheral base stations 103-1.
08 is the frequency of the common control channel.

In the base station 102, when the mobile station 101 starts communication, one of the frequencies of the common control channels used by the peripheral base stations 103 to 108 is used for each of the frequencies F2 to F7.
Notify. The mobile station 101 switches to the frequency notified from the peripheral base stations 103 to 108 at the time of the slot not used for communication and receives signals from the peripheral zone at timings 31a to 31f in FIG. The reception electric field levels of the peripheral base stations 103 to 108 are sequentially measured.

FIG. 5 is an explanatory diagram of a level measurement result and a correction operation in a mobile station according to one embodiment of the present invention. In the figure, a level 401 indicated by a broken line indicates a reception electric field level of the base station 102 during communication, levels 403 to 408 are reception electric field levels of the peripheral base stations 103 to 108, and a level correction value 409 is notified from the base station 102. Is done. Level 402 indicates the reception electric field level of the base station 102 during communication after the correction.

FIG. 6 shows a sequence of operation of one embodiment of the present invention. The operation of this embodiment will be described with reference to the sequence diagram of FIG.

For the channel of the base station 102 under communication, the mobile station 101 measures the reception electric field level by the reception level measurement circuit 204 and stores it in the memory in the control circuit 207 (step 501). Further, the mobile station 101 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 constant level of the base station 102, and if the received electric field level information from the mobile station 101 is higher than a predetermined level of the base station 102, the base station 102 The station 102 lowers the transmission power within a range that satisfies the predetermined transmission quality, and sets that value as the transmission power set value. 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 not exceeding the maximum transmission power, and that value is set as a transmission power set value (step 503). ). Further, a difference between the maximum transmission power of the base station 102 and the transmission power set value set in step 503 is obtained (step 505), and this is notified from the base station 102 to the mobile station 101 as a correction value (step 506).

As shown in FIG. 4, the mobile station 101 switches to the control channel frequency of the peripheral base stations 103 to 108 in the frames F2 to F7 at the time slot of the TDMA and measures the reception electric field level of the peripheral base stations 103 to 108. Further, as shown in FIG. 5, the received electric field level 401 of the channel under communication is corrected by the correction value 409 from the base station 102, and the corrected base station 102
Is set (step 507).

In FIG. 5, the highest reception electric field level of the peripheral base station with respect to the mobile station 101 is the reception electric field level 404 of the base station 104. The received electric field level 404 of the base station 104 is compared with the corrected received electric field level 402 of the base station 102 (step 509). At this time, the reception electric field level 402 of the base station 102
Is higher than the reception electric field level 404 of the peripheral base station 104, the mobile station 101 determines that the transfer is not a zone shift. If the received electric field level 402 of the base station 102 is lower than the received electric field level 404 of the peripheral base station 104, the mobile station 101 determines that the zone has been shifted (step 511).

In FIG. 5, the mobile station 101 before the transmission power of the base station 102 is corrected.
This shows an example in which the received electric field level of the peripheral base station 104 is higher than the received electric field level 404 of the surrounding base station 104 than the communicating base station 102, and the level 402 of the communicating base station 102 is higher after correction. . As described above, by notifying the mobile station 101 that is communicating the correction value 409 of the received electric field level from the base station 101, the mobile station 101 can perform an accurate zone shift determination even when the base station 102 is under transmission power control. it can.

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 the transmission power control, the base station 102 in communication sets the level of 401 in FIG. Will determine the 404 higher than the 401 as the migration destination zone and will switch the zone. On the other hand, according to the present invention, the received electric field level of the base station 102 during communication is set to 402 after correction, and the received electric field levels of the other base stations 103 to 108 are all lower than 401, so that the mobile station 101 Does not switch zones.

In the above example, an example in which the correction value is notified to the mobile station 101 only when the transmission power is changed in the base station 102 has been described. However, when the base station 102 does not have another control signal, the correction value is always set to the mobile station 101. By using a method of notifying 101 or a method of always providing a correction value by providing a dedicated control channel, the reliability of the control signal can be improved, and more reliable control can be performed.

In the above-described 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 set value or a value larger than the actual value is notified to the mobile station 101 as a correction value. Control is also possible. When the base station 102 notifies the mobile station 101 of a small value, the mobile station 101 performs zone determination before the zone boundary level, so that when traffic is concentrated in a specific area, the mobile station 101 There is an effect of dispersing 101 in peripheral zones. For example, the base station 102 where the mobile station 101 is located
Assuming that traffic is concentrated in this zone, and that the received electric field level of the peripheral base station 104 is higher than the other peripheral base stations, the mobile station 101 shifts to the zone of the base station 104.

Conversely, when the base station 102 notifies the mobile station 101 of a large value, the zone transition is not determined even if the zone boundary is exceeded to some extent, so that there is a large amount of traffic in the surrounding area and a small amount of traffic in the own station area. In addition, neighboring base stations 103-1
Channel switching to 08 can be suppressed.

〔The invention's effect〕

According to the present invention, when transmission power control is performed at the base station, the level is measured and the mobile station receives a lower value than when transmitting at the maximum output, but the base station moves the correction value. By notifying the station, accurate zone shift determination can be performed even when the base station performs transmission power control. Furthermore, by directly operating the correction value of the received electric field level to be notified to the mobile station, by avoiding the traffic distribution of the area from being concentrated on a specific zone,
This is extremely useful in practical use, for example, the call loss rate can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining the principle of the present invention, FIG. 2 is a system configuration diagram in a general automobile telephone system, FIG. 3 is a configuration diagram of a mobile station according to an embodiment of the present invention, and FIG. FIG. 5 is an explanatory diagram of a measuring operation in a mobile station according to one embodiment; FIG. 5 is an explanatory diagram of a level measurement result and a correcting operation in a mobile station according to an embodiment of the present invention; It is a figure showing a sequence. 101 mobile station, 102 to 108 base station, 201 modulation circuit, 202 demodulation circuit, 203 synthesizer, 204
Receive electric field level measurement circuit, 205: timing generation circuit, 206: encoding circuit, 207: control circuit, 208: decoding circuit.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Katsumi Kobayashi, inventor, 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Akira Hiroike, 1-16-1 Uchisaiwaicho, Chiyoda-ku, Tokyo Japan (56) References JP-A-59-161139 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H04B 7/24-7/26 H04Q 7/00- 7/38

Claims (2)

(57) [Claims] 1. A service area is covered by a plurality of base stations, communication is performed between a mobile station and a base station by a time division multiple access system, and transmission power of the base station is controlled according to a reception electric field level at the mobile station. In the mobile communication system zone determination method, the mobile station uses a measuring unit to determine a first zone of a communication zone in communication.
Measuring the first received electric field level of the peripheral zone and the second received electric field level of the peripheral zone, and transmitting the measurement result of the first received electric field level to the base station. The mobile station transmits information on the transmission power to the mobile station based on the received information on the transmission power and the reception electric field level of the wireless channel in communication corrected based on the received information on the transmission power.
A zone is determined by comparing the received electric field level with a received electric field level by a determination unit. 2. The mobile station receives, when the base station transmits reception electric field level correction information to the mobile station, the mobile station compares the received electric field level and determines a zone in which the mobile station is located. The zone determination method according to claim 1, wherein the reception electric field level of the wireless channel during communication is corrected based on the correction information.