JPH03104328A - Mobile communication control method - Google Patents

Abstract

PURPOSE:To control the size of a radio zone by correcting a reception level from a base station with a correction value of a reception level informed from the base station to a mobile station and informing the threshold level of the reception level required to make communication from each base station to the mobile station. CONSTITUTION:A correction value is informed to a mobile station 4 with an informing signal informed from base stations 1, 2, 3. Moreover, a mobile station 4 reads the correction value with the informing signal from the base stations 1, 2, 3 and measures the reception level 11 of the base stations 1, 2, 3 and obtains the reception level 11 of the base stations 1, 2, 3 and a reception level 12 after the correction to the base stations 1, 2, 3 from the correction value with the calculation. It is regarded by the correction that the radio zones of the base stations 1, 2, 3 are changed automatically. Thus, the size of the zone is controlled by calculating the correction value at the mobile station 4.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a method for determining a base station to call by controlling the boundary of a wireless zone in which a mobile device is located in a mobile communication system with a small zone configuration. It is.

(Prior Art) Hereinafter, a method for determining the radio zone in which a mobile device is located during a call will be described using a car telephone system as an example of a conventional mobile communication system.

In the car telephone system, all areas where the strength (reception level) of radio waves received by a mobile station from a base station are at a sufficient level for communication are defined as wireless zones. Although the size of this zone is affected by propagation conditions such as topography, it is basically determined by the transmission power of the base station.

FIG. 4 shows an example of zone determination during a call in a conventional car telephone system. FIG. 4(a) shows the zone configuration, and FIG. 4(b) shows the reception level from each base station at the mobile station. In FIG. 4(a), 1 to 3 are base stations, 4 is a mobile station, 5 is the zone of base station 1, 6 is the zone of base station 2, 7 is the zone of base station 3, and 8 is the zone of mobile station 4. A reception level threshold 31 necessary for communication indicates a zone determination boundary.

Next, a conventional zone determination operation during a phone call will be described.

For example, it is assumed that the mobile station 4 is located at a zone boundary of base stations and has a reception level that allows communication with these base stations. In other words, it is assumed that the reception level is higher than the threshold value 8.

Further, the reception level is assumed to be higher in the order of base station 1, base station 2, and base station 3 as shown in FIG. 4(b). The mobile station 4 selects the base station with the highest reception level and determines that it is in that zone. Even if all the communication channels of the base station 1 are in use, the mobile station 4 continues to select the base station 1 with the highest reception level due to the communication channel connection control algorithm, resulting in a call loss.

In this way, with conventional car phone systems, when setting up a wireless line for a call, the wireless zone in which the area is located is determined only based on the strength of the reception level. Even if there is a base station with a high reception level, call loss occurs and service deteriorates.

Further, FIG. 5 shows an example in which the zone determination of another conventional car telephone system is improved. In the same figure, 16
．． 17 is a base station, l8 is a zone of base station 1, 19 is a zone of base station 2, 21 is a mobile station, and 34 is a zone determination boundary.

Next, another conventional zone determination operation during a telephone call will be described.

For example, the mobile station 2l is located at the zone boundary between base station 16 and base station 17, has a reception level sufficient to communicate with both base stations, and has a higher reception level from base station 16. shall be. At this time, similar to the first conventional example above, when the base station 16 with a high reception level is determined to be in the own zone and a calling operation is performed, all communication channels of the base station 16 are in use. If so, the call will be lost. However, in another conventional example shown in FIG.
The mobile station 21 informs the mobile station 21 of other base stations since all communication channels in its own zone are in use and there are no free channels to reduce the number of lost calls.

(Problem to be Solved by the Invention) However, even in this conventional method, mobile stations randomly existing at zone boundaries are distributed to adjacent base stations.
If a mobile station exists at the edge of the zone of base station 17 (close to base station 16), the interference conditions with other base stations using the same channel will become severe, making it necessary to repeatedly increase the distance, etc. There are drawbacks.

The present invention is intended to solve these problems, and is a mobile communication system that can improve service by pseudo-controlling the size of its own zone under control from a base station and reducing call losses. The purpose is to provide a control method.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a reception system in which the base station notifies the mobile station of the reception level from the base station measured by the mobile station used for determining the wireless zone in which it is located. The feature is that the size of the wireless zone is controlled by correcting it with a level correction value and by notifying the reception level threshold required for communication from each base station to a mobile station. .

(Operation) Therefore, the present invention includes a plurality of base stations that transmit broadcast signals,
There is a mobile station that has the function of receiving broadcast signals from multiple base stations and the function of measuring reception levels, and small zone movement is configured such that the mobile station can compare the reception levels of multiple base stations. In a mobile communication system, each base station first notifies a mobile station of a correction value for the reception level, and the reception level of each base station measured by the mobile station is corrected using the correction value.

Furthermore, each base station notifies the mobile station of the reception level threshold required for communication. Therefore, the size of the wireless zone is controlled by correcting and changing the reception level threshold for determining callability for each base station.

Therefore, it is possible to improve the service by pseudo-controlling the size of the own zone under control from the base station and reducing call losses.

(Example) Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1(a) is a diagram showing a zone configuration of a first embodiment of the present invention. The figure (b) shows the amount of correction value broadcasted from each base station, and the figure (c) shows the reception level after correction.

Here, the correction value indicates the amount to be subtracted from the specified reception level. In other words, the larger the correction value is, the lower the actual reception level is determined to be. This embodiment shows an example in which a base station notifies a mobile station of a correction value of the reception level and performs zone determination. In FIG. 1(a), 1 to 3 are base stations, 4
is the mobile station, 5 is the zone before zone boundary control of base station 1, 6 is the zone before zone boundary control of base station 2, 7 is the zone of base station 3, and 8 is the zone where mobile station 4 is communicating. 9 is the zone after zone boundary control of base station 1, 10 is the zone after zone boundary control of base station 2, and 11 is the threshold of the reception level required for mobile station 4. The actually measured reception levels of the base stations 1 to 3, 12 the reception level corrected by the correction value, and 32 the zone determination boundary determined based on the corrected reception level.

Next, the operation of this embodiment will be explained. For example, when the traffic at base stations 1 and 2 is large and the communication channel usage rate is extremely high, mobile station 4 at the zone boundary
An example will be described in which the wireless zone determination is performed so that the base station 3 exists in the zone of the base station 3.

First, here, the mobile station 4 is located, for example, at the zone boundary of all the base stations, and has a reception level that allows it to communicate with all the base stations. In other words, the zone of each base station before receiving level correction is indicated by a dotted line in FIG. 1(a), and it is assumed that the mobile station 4 is located at a position that is included in the zone of all base stations.

Further, at this time, the reception level is assumed to be higher in the order of base station 1, base station 2, and base station 3, as shown by reception level l1 in FIG. At this time, the mobile station 4 is notified of the correction value shown in FIG. 4(b) using a broadcast signal broadcast from each base station.

In addition, the mobile station 4 reads the correction value from the broadcast signal from each base station, measures the reception level 1l of each base station, and calculates the correction value for each base station from the reception level 11 of each base station and the correction value. The reception level l2 is calculated.

As a result, base station 1 and base station 2 are connected as shown in FIG.
The corrected reception level 12 from the base station 3 is lower than that from the base station 3, and the corrected reception level l2 increases in the order of, for example, the base station 3, the base station 2, and the base station 1. If zone determination is performed using this corrected reception level l2, mobile station 4
It is possible to cause the base station 3 to determine that the base station 3 exists.

In other words, it can be considered that the wireless zone of each base station has automatically changed due to this correction. The new zones are zones 9 and 10 shown in solid lines in FIG. 1(a).

In this way, the size of the zone can be controlled by calculating, at the mobile station, the reception level measured by the mobile station and the correction value broadcasted from the base station. Further, since the base station broadcasts the correction value, the base station can select the correction value, and the size of the zone can be freely changed under the control of the base station alone.

By making the correction value broadcast from the base station correspond to the channel usage rate of each base station in this way, call loss can be reduced. For example, if base station 1 and base station 2 have a high channel usage rate and base station 3 has a low channel usage rate,
By increasing the correction values for base station 1 and base station 2 and decreasing the correction value for base station 3, a reversal of the reception level occurs, and mobile station 4 considers base station 3, which has a low channel usage rate, as its own zone. can do.

In this way, by using the zone boundary control method of this embodiment and also by associating the correction value with the channel usage rate of the base station, it is possible to control the channel usage rate of adjacent base stations, reduce call loss, and increase the frequency. It can be used effectively.

Next, FIG. 2(a) shows a zone configuration of a second embodiment of the present invention, and FIG. 2(b) is a diagram showing reception levels and threshold values. An example will be shown in which a zone determination is performed by notifying a reception level threshold necessary for communication from a base station to a mobile station according to the present embodiment. In the same figure (a), 1 to 3 are base stations, 4 is a mobile station, 5 is a zone before zone boundary control of base station 1, 6 is a zone before zone boundary control of base station 2, and 7 is the zone of base station 3, 11 is the reception level of the base station received by the mobile station, 13 is the zone after zone boundary control of base station 1, and l4 is the threshold notified from the base station to the mobile station. The value 15 indicates the difference between the reception level and the threshold value, and 33 indicates the zone determination boundary corresponding to the new wireless zone after executing this embodiment.

Next, the operation of this embodiment will be described, taking as an example a case where the size of the zone is changed so that the mobile station 4 located at the zone boundary of all base stations is present in the base station 3. That is, it is assumed that the mobile station 4 is located at a zone boundary and has a reception level that allows communication with all base stations. The reception level is assumed to be highest in the order of base station 1, base station 2, and base station 3. At this time, the threshold value 14 shown in FIG. 2(b) is reported by a broadcast signal broadcast from each base station. The mobile station 4 reads broadcast signals from each base station, measures the reception level of each base station, and determines the reception level 11 of each base station.
and the threshold value l4. At the base station 1 shown in FIG. 4(b), the reception level is lower than the threshold value, so communication becomes impossible. This means that the zone is made smaller like zone l3 of base station 1, and the size of the zone is controlled in a pseudo manner. Here, when performing zone determination,
Assuming that the base station with the largest difference between the reception level 1l and the threshold value l4 is selected as the own zone, the difference between the reception level 11 of the base station 2 and the threshold value 1 as shown in FIG.
Since the difference l5 between the reception level l1 of the base station 3 and the threshold value l4 is larger than the difference l5 between the reception level l1 of the base station 3 and the threshold value l4, the mobile station 4 can select the base station 3 as its own zone.

In this way, by comparing the reception level measured by the mobile station with the threshold value broadcasted from the base station by the mobile station, it becomes possible to control the zone boundary. In addition, in order to broadcast the threshold value from the base station, the threshold value can be selected by considering the channel usage rate, etc., as in the previous section, and the zone size and channel usage rate can be controlled by only the base station. has.

FIG. 3 shows an example of an application form of the present invention.

16. 17 is the base station, l9 is the zone of base station 17, 2
3 to 25 are zones of the base station 16 (sizes are changed due to zone boundary control), 27 to 29 are mobile stations, and 35 to 25 are mobile stations.
37 indicates a zone determination boundary when the base station 16 is in zones 23 to 25. Mobile station 27 exists on the zone boundary between base station 16 and base station 17, has a reception level that allows communication with both base stations, and base station 16 has a higher reception level than base station 17.
Assume that there is a communication channel with a high reception level and an empty communication channel, but the channel usage rate is high. At this time, in the conventional method, the mobile station 27 determines that the base station 16 with the highest reception level is in its own zone. However, by using this embodiment, the zone 23 of the base station 16 is made smaller in proportion to the high channel usage rate of the base station 16, and the zone 23 of the base station 16 is changed to zone 2.
4, the mobile station 27 determines that the base station 17 is in its own zone.

Furthermore, if the channel usage rate of the base station 16 is high,
By setting the zone of the base station 16 to zone 25, the mobile station 28 also determines that the base station 17 is its own zone. Furthermore, if the mobile station 29 is present at this time, the mobile station 29 can make the base station 16 its own zone. In the conventional improved type, in such a case, the base stations 16 and 17 are assigned according to the order in which the mobile stations are present, but in this embodiment, the base stations can be assigned according to the location where the mobile stations are present. Mobile stations existing near base station 17 can be preferentially determined to be in the zone of base station 17. This has the advantage of easing interference conditions and shortening the repeat distance with base stations that use the same channel.

As described above in detail, the method of the present embodiment has features such as being able to control the zone size and channel usage rate, and also being able to alleviate interference conditions.

In addition, as actual control methods, there are two methods: one is to control the correction value and threshold value according to the measurement results of the channel usage rate for a certain period of time, and the other is to control the correction value and threshold value at relatively quick intervals depending on the number of remaining channels. Methods of controlling the threshold value can be considered, and control using a combination of these methods can also be considered. By using such a control method, the zone boundary control method of this embodiment is particularly effective when the mobile station moves and the traffic for each zone changes depending on the time of the day or depending on the day. .

(Effects of the Invention) As described above in detail, the method of the present invention has the advantage that the size of the zone can be freely changed under control from the base station. Further, it has the advantage of being able to control the channel usage rate of the base station, reducing call loss, alleviating interference conditions, and making effective use of frequencies.

[Brief explanation of drawings]

FIG. 1(a) is a diagram showing the zone configuration of the first embodiment of the present invention, FIG. 1(b) is a diagram showing the amount of correction values broadcast from each base station, and FIG. 1(C) is a diagram showing the amount of correction values broadcast from each base station. FIG. 2(a) is a diagram showing the reception level after correction. FIG. 2(a) is a diagram showing the zone configuration of the second embodiment of the present invention. FIG. 2(b) is a diagram showing the reception level and threshold value. 4 is a diagram showing an example of the effect when the zone boundary control method of the present invention is performed; FIG. 4 is a diagram showing a zone configuration when zone determination is performed during a call in the first conventional car telephone system; FIG. 4(b) is a diagram showing the reception level from each base station at the mobile station, and FIG. 5 is a diagram showing an example in which an improvement is made to the zone determination of the second conventional car telephone system. be. 1-3. 16.17: Base station, 4, 21. 27 to 29: Mobile station, 5: Zone before zone boundary control of base station 1, 6: Zone before zone boundary control of base station 2, 7: Zone of base station 3, 8: Mobile station 4 9, 13: Zone after zone boundary control of base station 1, lO: Zone after zone boundary control of base station 2, l1 : Base station reception level received by the mobile station, l2:
Reception level corrected by correction value, 14: Threshold value notified from the base station to the mobile station, l5: Difference between reception level and threshold value, 18: Zone of base station l6, 19: Zone of base station l7 , 23-25: zone of base station 16, 32, 33: zone determination boundary, 35-37: zone determination boundary when the zone of base station 16 is zone 23-25. Figure 2 19.23-25: No 35-37: No ゛ ゜ 一冫≠+i-kome 1-】Yumihito Kōgata Ikkun Figure 3 A) (Fig. 4

Claims (4)

[Claims] (1) There are multiple base stations that transmit broadcast signals and a mobile station that has the function of receiving broadcast signals from multiple base stations and the function of measuring reception levels, and the reception levels of multiple base stations can be measured by the mobile station. In a small-zone mobile communication system that is configured to allow comparisons, each base station notifies the mobile station of a correction value for the reception level, and the reception level of each base station measured by the mobile station is calculated using the correction value. A mobile communication control method characterized by correcting. (2) The mobile communication control method according to claim 1, wherein the correction value is changed according to the channel usage rate of each base station. (3) There are multiple base stations that transmit broadcast signals and mobile stations that have the function of receiving broadcast signals from multiple base stations and the function of measuring reception levels, and the reception levels of multiple base stations can be measured by the mobile station. In a small zone mobile mobile communication system configured to enable comparison between base stations and mobile stations, mobile communication control is characterized in that a reception level threshold required for communication from each base station to a mobile station is notified. Method. (4) The mobile communication control method according to claim 3, wherein the threshold value is changed according to the channel usage rate of each base station.