JPS62128227A - System for detecting location of mobile station - Google Patents

Abstract

PURPOSE:To obtain an accurate long period mean reception level with a few number of receivers by obtaining plural periodic short-time reception levels as to each mobile station and regarding the mean value as a mean reception level. CONSTITUTION:When a base station 1 during talking detects that the level of the talking channel of a mobile station is decreased than a threshold L, the station 1 sends a switching request signal to a control station 7, which sends a level request signal to the peripheral base station of the base station 1. Each base station calculates a long period mean value based on a data till that point of time when a reception level measuring receiver receives a ratio wave sent from the mobile station during talking intermittently and sends the result to the control station 7 as a level report.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for detecting the position of a mobile station in a mobile communication system for establishing a small wireless zone. The present invention relates to a method of measuring at each base station and determining the wireless zone in which a mobile station is located.

[Conventional technology]

In mobile communications, in order to effectively use radio frequencies, one base station's wireless zone (hereinafter also referred to as zone)
The current trend is to reduce the frequency and use the same frequency repeatedly in separate zones.

Therefore, when a mobile station is traveling regularly while communicating with a base station, there are many opportunities to shift from one zone to another. In this case, in order for communication to be performed without interruption, it is necessary to constantly know the location of the mobile station and to appropriately switch the wireless channel used for communication when changing zones. The switching must have been carried out accurately. If the 4i11 is used with a 4i11 mode, the propagation loss will increase, resulting in a decrease in the quality of communication. interference on the same channel.

I will be able to do it.

A mobile station position detection method that has been conventionally used to detect the time point at which the wireless channel is switched, that is, the transition of zones, will be described with reference to the drawings.

FIG. 1 is a diagram showing an example of the configuration of a mobile communication system consisting of a plurality of wireless zones.

In FIG. 1, base stations 1, 2, and 3 each have a wireless zone 4, 5, and 6 as their service area, and base stations 1, 2, and
．． 2.3 is centrally controlled by the control station 7. Communication between adjacent radio base stations 1.2.3 and mobile stations uses different radio channels to prevent interference between adjacent zones.

Mobile station 8 in zone 4 moves toward zone 5 as shown by the arrow while communicating with base station 1, and the radio wave f^ of the mobile station becomes low reception level at base station 1, and high reception level at base station 2. The flowchart in Figure 2 and the operation of the receiver for measuring the reception level in Figure 3 are explained regarding the conventional control for detecting the transition of the wireless zone when the user moves to an area where the level is L-. This will be explained using a diagram.

The base station 1 monitors the reception level of the radio channel rA that the mobile station 8 is transmitting, and the mobile station 8 detects that the reception level at the base station 1 has reached a specified threshold (when the mobile station is near the zone). When the base station 1 reaches point A, which exceeds the measurement level), the base station 1 transmits a channel switching request with the measurement level added to the control station 7.

When the control station 7 receives the switching request signal from the base station 1, it transmits a level request to base stations 2, 3, etc. in the vicinity of the base station 1. The base station that received the level request measures the level LA of the radio channel fA transmitted by the mobile station 8 using a reception level measurement receiver as shown in FIG. 3, and sends the measurement result as a level report to the control station 7. Send.

The control station compares these level reports and the level added to the channel switching request, determines that the zone of the base station with the highest level is the location of the mobile station and the transition destination zone, and switches the wireless channel. Make the switch.

In Figure 1, since base station 2 is the closest to point A, the level of base station 2 should be higher than the levels of base station 3 and base station 1, and these levels are determined by the central station. By comparing, a transition from zone 8 to zone 5 is detected.

[Problem that the invention seeks to solve]

Conventionally, level measurement for mobile station position detection is started by a control station issuing a command to surrounding base stations when the reception level of a communicating base station falls below a threshold. Therefore, it was necessary to perform measurements in a short period of time to prevent communication quality from deteriorating due to movement of the mobile station during measurement.

! r-7. M 11411411fih:ffi unit +
-7 I-) 7.6 pickles I+.

There are strong fluctuations in , and therefore short-term measurements are not the best measurement method to use to determine zone transitions.

The fluctuation characteristics of this reception level will be described in detail below.

FIG. 4 is a diagram showing an example of propagation characteristics in land mobile communication, in which (a) shows fluctuations in a short period, (b) shows fluctuations in a long period, and (e) shows the long period average value and distance. It shows the relationship between

In this way, fluctuations in reception level are centered around a long-term average value (for car phones, the average value over 10 to 15 seconds) that attenuates with distance, and a combination of slow local fluctuations and fast instantaneous fluctuations. has been done.

The destination zone of the mobile station is determined based on the fact that this long-term average value corresponds to the distance from the base station as shown in Figure 4(c), so the accurate long-term average value is determined. If this information cannot be obtained, there is a risk that the location of the mobile station, that is, the destination zone will be incorrectly determined. However, in the average value of the reception level over a short period of time, local variations and instantaneous fluctuations are not sufficiently averaged, resulting in an error from the actual long-term average value.

In this way, with conventional level measurements, only the average reception level of 1-11'F open can be obtained, so accurate long-term average values cannot be obtained, and the mobile station position cannot be determined correctly. There was a drawback.

The present invention solves the conventional drawback that measurement of the average reception level at a base station can only be carried out for a short period of time.
The object of the present invention is to provide a highly accurate mobile station 11γ1 detection method that can accurately determine the compensation level over a long period with a small number of receivers.

[Means to solve the problem]

According to the present invention, the above object is achieved as stated in the claims.
This is achieved by this means.

That is, in the present invention, when measuring the average reception level of a wireless channel that a mobile station is transmitting, the reception level of a plurality of channels is measured by changing the reception FyJ(t"J') of one receiver one after another. The most important feature is that by sequentially measuring short periods of time and repeating this, multiple periodic short-term reception levels are obtained for each mobile station, and the average of these is regarded as the average reception level. This method is different from the conventional technology in that the average reception level of each successful or unsuccessful mobile station can be obtained at the same time in one reception.

〔Example〕

FIG. 5 is a 70-chart illustrating the control of one embodiment of the present invention. Further, FIG. 6 is a diagram showing the operation of the reception level measuring receiver in the above embodiment.

In the case of the present invention, as shown in the PtS1 diagram, the configuration and functions of base stations 1 to 3 and the control station 7 are the same as in the conventional system, but the operation of the reception level measuring receiver is different.

That is, as shown in FIG. 5, when the base station 1 in communication detects that the level of the channel in communication of the mobile station is 7" below the threshold, it sends a switching request signal to the control M7,
The central station 7 that has received this sends a level request signal to base stations surrounding the base station 1 (up to this point, it is the same as the conventional system). Each base station does not measure the level of the specified channel from the moment it receives a level request as in the past, but instead the reception level measurement receiver intermittently receives the radio waves transmitted by the mobile station in communication. A long-term average value is calculated based on the data obtained up to that point and sent to the control station 7 as a level report. The operation of the reception level measuring receiver in this case will be explained in more detail with reference to FIGS. 1 and 6.

As shown in FIG. 1, it is assumed that base station 1 is provided with radio channels of frequency FA, and base station 3 is provided with radio channels of frequencies fB and fc. In this case, the channels used by mobile stations in the surrounding base stations of base station 2 are fAs f'B , f
(H, and these channels can be monitored.

The present invention constantly monitors these channels regardless of whether there is a level request, and one receiver 1Jl14h4L)
/PIA,,4+++,-m+1Jb-3τ+1e2-
1-TjJxs4%4ru.

As shown in FIG. 6, by repeatedly measuring the level of each channel for a short period of time while switching channels, the average of the sinus chamber results several times can be regarded as a long-term average value.

FIG. 6 shows a case where three channels are measured three times each at a measurement period Tf. As mentioned above, there are fluctuations in the reception level with respect to the long-term average value, and short-time level measurements cannot absorb the fluctuations and a standard deviation exists. This standard deviation becomes smaller as the measurement time becomes longer, but since the pitch fm of local fluctuations is generally very slow at 0.2 Hz, if the receiver is used for a limited time, it will be concentrated continuously. It is better to measure intermittently for short periods of time than to measure
Standard and deviation can be reduced.

The PtS7 diagram shows the characteristic of the standard deviation when measurements are intermittently repeated many times in this way, with the usage time of the receiver constant.

In the same figure, it can be seen that when the same measurement time opening T is given, the larger the number of receptions NS performed within the Tr is, the more advantageous it is, even though the reception time per time becomes shorter.

In other words, it is more advantageous to measure more times than to measure for a long period of time, even if the time is short. Therefore, the measuring method shown in FIG. 6 can clearly obtain a more accurate long-term average value than the conventional level measuring method shown in FIG.

Perform such measurements and find the average value. : Accordingly,
When a level request is received from the control station, a level report can be made immediately.

For example, in FIG. 6, the latest past three measurement results U-AI, 1-A2, LA are always stored, and when a level request is received, their average (L Al +I
-A2 +LA))/3 is sent as a level report.

The average value of the reception level may be determined by a moving average instead of a simple average.

As is clear from these results, compared to the conventional technology 1U, reception 1/Bell measurement reception 1. ;view, u・ra 慴】°, f
l-? jv'Ken-ia L/ Hell L) (Correct = lW
'%'+',>)ru, two (1, ri, l; (,□i
From 2 to 2, Jl:, it is possible to quickly detect the mobile station position by shortening the IL season 11#) from 2 station level' to 5 request/reception ffl to level report sending ii. Becomes Noh. 1. FIG. 23 is a flowchart illustrating control in another embodiment of the present invention.

FIG. 9 is a diagram illustrating the operation of the reception level measuring receiver in the above embodiment.

This embodiment is shown in FIG. 5 and is different from the other embodiment in that the channel to be measured by the reception level measuring receiver is not all the channels used by the mobile station in the surrounding base stations, but IJI! It is located in a place where only channel A in 'M' is available. An embodiment of such a method of monitoring only the channel in the channel 4g will be described with reference to FIGS. 3 and 9.

As shown in FIG. 8, each base station sends the start and end of communication of each channel of the base station to the central station 7 as a communication start notification and a communication end notification. The control bureau receives this information. :By broadcasting once a month, each base station receives monitoring reception f as shown in Figure 9.
Based on this information, it is possible to limit the channels measured by f1fi to only those that are currently communicating. FIGS. 8 and 9 show a case where communication on channel f ends at base station 1 and communication on channel r2 starts.

In this way, by measuring only the level of the channel during communication, $I is reduced compared to the embodiment shown in FIG.
Although it becomes more complicated, efficient channel monitoring becomes possible, and the number of channels that can be monitored by the receiver for receiving 1/bell measurement can be increased and the number of channels can be increased.

〔Effect of the invention〕

As explained above, according to the method of the present invention, compared to the conventional technology, the average reception level obtained from the reception level measuring receiver is more accurate, and the level report from the level request reception at the base station is more accurate. Since the time until transmission can be shortened, the mobile station position can be detected accurately and quickly.

[Brief explanation of drawings]

Figure 1 shows a mobile Jffi (,
A diagram showing an example of the configuration of the r method; FIG. 2 is a flow chart explaining control of mobile station position detection in the conventional method 11;
Figure 3 shows the conventional reception level measurement method. A diagram explaining the operation of Nobuiso, Figure 154 is a diagram showing the propagation characteristics of land mobile communication,
FIG. 5 is a flowchart explaining the control of an embodiment of the present invention, FIG. 6 is a diagram showing the operation of reception 1/bell measurement reception in an embodiment of the present invention, and FIG. ')
Characteristics of the standard deviation of the received level when measuring i14.・1
Figure 8 is a 70-chart explaining the control of another embodiment of the present invention. FIG. 3 is a diagram illustrating the operation of the reception level measuring receiver in the missing example of the present invention. 1.2.3 ...Base station, 4.1), (3.
...Zone, 7 ...Control Bureau, N≦
・・・・・・Press mobile station t'lAA+nQlI
Gi! ) A graduate / Figure graduate 2nd figure rod ,, 3 Figure 4 g 7 23 1f/l) 2t), 30 60 1 (X
) Construction area (KVRn Figure 5 Figure 6 Figure 6

Claims (1)

[Claims] A service area is made up of a collection of wireless zones of multiple base stations, and base stations and mobile stations communicate using wireless channels, and base stations can communicate with each other using fixed lines installed between them. In a certain mobile communication system, each base station uses a reception level measurement receiver with a variable reception frequency to sequentially and repeatedly measure the reception level of each radio channel frequency transmitted by a plurality of mobile stations. Then, calculate the average value of the reception level measured multiple times for each mobile station, compare the average value for each mobile station between base stations, and select the wireless zone of the base station with the highest average value for the corresponding mobile station. A mobile station position detection method characterized by determining a wireless zone in which a mobile station is located.