JPH06350515A - Mobile communication equipment and mobile station equipment - Google Patents

Abstract

PURPOSE:To exactly judge zones by measuring the level of a received electric field from a peripheral base station with a frequency band different from its frequency band and correcting the level of a received electric field from a base station under communication corresponding to the difference of the frequency band. CONSTITUTION:A mobile station 20 measures the received electric field level (the first received electric field level) of the frequency band under communication and the received electric field level (the second received electric field level) of the frequency band for zone judge from the peripheral zone and transmits the measured result of the first received electric field level to a base station 11. Based on this result, the base station 11 transmits information for converting the received electric field level of that frequency band to the received electric field level of the frequency band for zone judge to the mobile station 20 as correction information. Corresponding to this correction information, the mobile station 20 corrects the first received electric field level just as the frequency band for zone judge is received. Further, the mobile station 20 judges its own existent zone by comparing the corrected value with the second level of the electric field received from the peripheral zone.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in a mobile communication system using a plurality of frequency bands in a small zone configuration. In particular, it relates to determination of the zone where the mobile station is located.

[0002]

2. Description of the Related Art A car telephone system is known as a typical example of a mobile communication system having a small zone configuration. In such a communication system, a mobile station and a radio base station (hereinafter simply referred to as “base station”)
Time division multiple access (TDMA)
Method is used. Further, as the frequency band, the 800 MHz band has been conventionally used, but more recently, it has become possible to use the 1.5 GHz band, and it is necessary to use a plurality of such frequency bands in the same service area. Became possible.

When a plurality of frequency bands are used in this way, the time that is not used for communication is used, and zone determination is performed using a frequency band different from the frequency band used for that communication. be able to. That is, the mobile station is 1.5
During a call in the GHz band, the reception level in the 800 MHz band of the frequency zone is measured in a time slot that is not used for the call, and zone determination is performed based on the measurement result. By doing so, it is possible to speed up zone determination, and further, it is possible to distribute the load on the control device of the base station.

Zone shift detection by the mobile station is performed as follows. That is, the mobile station compares the received electric field level of the wireless channel in communication with the received electric field level of the peripheral zone, and if the received electric field level of the peripheral zone is high, it is determined that the zone transition has been performed.

[0005]

However, when a signal is transmitted in each of a plurality of frequency bands from the base station side, the propagation distance varies depending on the frequency band due to the nature of radio waves. For example, when the propagation distance of the frequency band for zone determination is longer than the propagation distance of the frequency band in communication, the frequency band for zone determination reaches farther, and the received electric field level at the mobile station is It becomes higher than the frequency band. In such a case, if the reception levels are compared directly, the reception levels from neighboring base stations will be generated even though the mobile station's zone is actually the wireless zone of the base station in communication. Because it is high, it will be judged that it has moved to the zone. However, since the propagation distance of the frequency band for actual communication is short, even if an attempt is made to use the frequency band in a new zone for communication, a sufficient reception level cannot be obtained. In order to avoid this, it is necessary to receive all control channels for a plurality of frequency bands from the peripheral zone even if the radio waves are from the same base station. Therefore, the power consumption of the mobile station is high.

An object of the present invention is to solve the above problems and provide a mobile communication device capable of accurately determining the zone in which a mobile station is located.

[0007]

A first aspect of the present invention is a mobile communication device, which communicates with a plurality of radio base stations arranged in a service area and individual radio base stations by a time division multiple access system. A mobile station capable of receiving the radio signals from the radio base station with which the mobile station is in communication and the radio base stations in the vicinity of the mobile station and measuring the received electric field level thereof; In a mobile communication device including means for comparing the electric field levels and determining a zone in which the user is located, a plurality of radio base stations are configured to perform transmission and reception of control channels and communication channels in a plurality of frequency bands, respectively. The station controls the means for selecting one of a plurality of frequency bands as the transmission / reception frequency, the means for selecting this, and the means for measuring the received signal in the time slot during communication. In a time slot that is not used for communication, the control means that selects a frequency band that is not used for communication and supplies it to the means that measures the radio signal from the surrounding radio base station, and the radio base station of the communication partner And a measurement value notifying means for notifying the radio base station of the measurement value of the reception electric field level of the radio base station, the radio base station, and means for obtaining a correction value for the measurement value notified from the mobile station based on the difference in the frequency band. , A correction value notifying means for notifying the mobile station of the correction value, and the means for determining has a reception electric field level corrected by the correction value from the correction value notifying means and a reception electric field level from a peripheral radio base station. And means for comparing.

A second aspect of the present invention is a device used as a mobile station in the mobile communication device according to the first aspect, comprising means for selecting any of a plurality of frequency bands as a transmission / reception frequency and means for selecting this. It controls and supplies the received signal to the means for measuring the received signal in the time slot during communication, selects the frequency band not used in the communication in the time slot not used for communication, and selects the frequency band from the surrounding wireless base station. A control means for supplying the radio signal to the means for measuring and a measurement value notifying means for notifying the radio base station of the measurement value of the received electric field level from the radio base station of the communication partner are provided, and the correction value from the base station is used. It is characterized in that it comprises means for comparing the corrected received electric field level with the received electric field level from the surrounding wireless base station.

[0009]

In the mobile station, the received electric field level in the frequency band in communication and the received electric field level in the frequency band for zone judgment from the surrounding zone are measured, and the measurement result of the received electric field level in the frequency band in communication is measured. To the base station. The base station in communication determines a correction value of the electric field level of the wireless channel in communication with respect to the information from the mobile station, and transmits the correction value to the mobile station. As a method of obtaining the correction value, for example, the relationship between the reception electric field levels of the plurality of frequency bands may be measured and stored in advance, and the correction value may be read according to the information from the mobile station. The mobile station that received the correction value
The received electric field level of the wireless channel during communication is corrected as if the electric wave in the frequency band for zone determination is received, and the corrected electric field level is compared with the received electric field level of the peripheral zone. At this time, if the reception electric field level in the peripheral zone frequency band is higher, the zone transition processing is performed, and if it is low, the processing is not performed. Therefore, the mobile station can determine its own accurate zone.

[0010]

1 to 3 are diagrams showing the configuration of a mobile radio apparatus for carrying out the present invention. FIG. 1 shows the arrangement of a mobile station and a base station which are in communication with each other, and a surrounding base station, and FIG. Is a partially rewritten version thereof, and FIG. 3 shows the relationship between a mobile station and a base station.

This mobile radio apparatus includes a plurality of radio base stations arranged in a service area, and a mobile station capable of communicating with each radio base station by a time division multiple access system.
In FIG. 1, only the base stations 11 to 17 are shown as radio base stations, and only the mobile station 20 is shown as a mobile station. It is assumed that the mobile station 20 is in communication with the base station 11. Base stations 11 to 1
7 uses two frequency bands A and B in each zone, and at least one control channel to be used is set for each frequency band of the zone. This control channel is always transmitted with the maximum output that can be set by each base station.

FIG. 3 shows two types of mobile stations 20 and 30 with respect to the base station 11. The base station 11 has two frequency bands A,
B is used, and the mobile station 20 can also transmit and receive in frequency bands A and B. On the other hand, the mobile station 30 is a conventional mobile station, and corresponds to only the frequency band A and the base station 11
Can communicate with. The mobile station 20 uses the frequency band A,
Since it is compatible with any of B, and is a form in which two mobile stations corresponding to one frequency band such as the mobile station 30 are combined, it is called a dual mobile station.

FIG. 4 is a diagram showing a control flow of the base station 11 and the mobile station 20 for the mobile station 20 to determine the zone in which the mobile station 20 is located.

The mobile station 20 receives radio signals from the communicating base station 11 and the surrounding base stations 12 to 17 and measures the received electric field level. That is, the mobile station 20 receives the reception electric field level in the frequency band during communication (hereinafter referred to as “first reception electric field level”) and the reception electric field level in the zone determination frequency band from the surrounding zone (hereinafter referred to as “first reception electric field level”). Second received electric field level "),
The measurement result of the first received electric field level is transmitted to the base station 11. The base station 11 transmits, to the mobile station 20, information for converting the received electric field level in the frequency band into the received electric field level in the zone determination frequency band based on the received first received electric field level as correction information. . This correction information can be easily transmitted using, for example, a bit for notifying the mobile station in communication of the transmission power control information of the base station realized by the current technology. Based on this correction information, the mobile station 20 corrects the first received electric field level as if it had received the zone determination frequency band. The mobile station 20 further compares the corrected value with the second received electric field level received from the surrounding zone to determine its own zone.

FIG. 5 is a block diagram showing an example of the mobile station 20. The mobile station 20 includes a modulation circuit 21, a demodulation circuit 22, a frequency synthesizer 23, a reception level measurement circuit 24, a timing generation circuit 25, an encoding circuit 26, a control circuit 27 and a decoding circuit 28.

The modulation circuit 21 modulates the code input from the encoding circuit 26 and transmits it. The demodulation circuit 22 demodulates the received signal. The frequency synthesizer 23 supplies a local oscillation signal to the modulation circuit 21 and the demodulation circuit 22. The reception level measuring circuit 24 measures the reception power level in the demodulation circuit 22. At this time, the reception level measuring circuit 24 switches the oscillation frequency of the frequency synthesizer 23 under the control of the control circuit 27 so as to be able to receive respective radio signals from the base station in communication and the base stations in the vicinity thereof, and respectively. Measure the received electric field level of. The timing generating circuit 25 reproduces the frame timing from the received code, and the receiving level measuring circuit 24 and the encoding circuit 2
6 to control the operation timing. The encoding circuit 26 encodes an information signal input from the outside and multiplexes it with a control signal from the control circuit 27 into a TDMA frame.
The control circuit 27 controls the operation of the mobile station in accordance with the control information from the base station decoded by the decoding circuit 28, and further compares the reception electric field level measured by the reception level measuring circuit 24 with its own. Determine the zone in which you are located. The decoding circuit 28 decodes the received signal, separates the received signal into a control signal and an information signal, and outputs the control signal to the control circuit 27.

Here, the frequency synthesizer 23 can select one of a plurality of frequency bands A and B as a transmission / reception frequency, and the reception level measuring circuit 24 supplies the reception signal to the demodulation circuit 22 in the time slot during communication. , The frequency synthesizer 23 is controlled so as to supply the radio signal from the peripheral base station to the demodulation circuit 22 by selecting the frequency band not used for the communication in the time slot not used for the communication, The received electric field level at 22 is measured. This measured value is stored in the memory in the control circuit 27, and the measured value of the received electric field level from the base station of the communication partner is controlled by the control circuit 27 via the encoding circuit 26 and the modulation circuit 21 via the control channel. Notify the station. The control circuit 27 also receives, via the demodulation circuit 22 and the decoding circuit 28, the received electric field level correction value notified from the base station via the control channel, and corrects the received electric field level from the base station by the correction value. , And compares the corrected received electric field level with the received electric field levels from the surrounding base stations.

FIG. 6 is a diagram for explaining the operation of measuring the received electric field level in the mobile station, where (a) shows the received signal of the mobile station and (b) shows the received frequency of the mobile station. The mobile station receives the information signal from the base station of the communication partner in the frame of frequency F1 belonging to frequency band A, and further receives the common control channel of frequency band B from the surrounding base stations in the frames of frequencies F2 to F7. To further explain this, when the mobile station starts communication, the base station selects one from among the frequencies of the common control channel used by the peripheral base stations.
Each of them is selected and the frequencies F2 to F7 are notified to the mobile station. The mobile station sequentially switches the reception frequency during the slots not used for communication to frequencies F2 to F7, receives signals from the peripheral zone, and measures the received electric field level.

FIG. 7 is a diagram for explaining the relationship between the level measurement result at the mobile station and the correction operation. The mobile station measures the reception electric field level of the communication channel from the base station during communication and the reception electric field level of the common control channel in a frequency band different from that of the communication channels from the peripheral base stations. In FIG. 7, the reception electric field level of the communication channel is indicated by a broken line.

FIG. 8 shows an operation sequence between the mobile station and the base station. Here, it is assumed that the mobile station communicates with the base station on the communication channel of the frequency band A and receives the common control channel from the peripheral base stations on the frequency band B different from the frequency band A.

The mobile station measures the communication channel with the base station with which it is communicating and records it in the memory in the control circuit. Furthermore, the mobile station notifies the base station of the measured received electric field level using the control channel. The base station obtains a value for converting the reception level of the frequency band A into the reception level when receiving the radio wave of the frequency B from the received electric field level information received from the mobile station, and notifies the mobile station of this value as a correction value. . The mobile station measures the reception electric field level of the common control channel from the peripheral base station by using the time slot that is not used for communication of the mobile station. Further, the received electric field level of the channel in communication is corrected by the correction value from the base station, and the corrected level is regarded as the received electric field level from the base station in communication.

Assuming that the received electric field level from the second peripheral base station is the highest as shown in FIG.
The received electric field level from the second peripheral base station is compared with the corrected received electric field level from the in-call base station. At this time, if the received electric field level of the base station during communication is higher than the received electric field levels of the peripheral base stations, the mobile station determines that the zone transfer is not performed. If the received electric field level of the base station during a call is lower than the received electric field level of the neighboring base stations, the mobile station determines that the zone transition has occurred.

In the example shown in FIG. 7, the reception electric field level before correction from the base station during communication is lower than the reception electric field level from the second peripheral base station, and after correction (solid line) from the communication base station. The received electric field level is higher. In such a case, the base station notifies the mobile station in communication of the correction value of the received electric field level, thereby controlling the frequency band B of the peripheral base station even if the base station is in communication in the frequency band A. Only by measuring the channel, the mobile station can make an accurate zone transition decision.

That is, when the mobile station is not notified of the correction value at the time of frequency band conversion in the base station, the actual received electric field level from the communicating base station is used to compare with the received electric field level from the peripheral base station. Therefore, the mobile station determines the second peripheral base station whose received electric field level is higher than that during the call as the transfer destination zone, and switches the zone. On the other hand, if the reception electric field level is corrected, the reception electric field level from the communicating base station is corrected to be higher than the reception electric field level from the second peripheral base station, and the reception electric field from another peripheral base station is received. All levels are lower than that and the mobile station does not perform zone transition.

When converting the frequency band, it is possible to notify the mobile station of a value smaller than or larger than the actual correction value. When a small value is notified to the mobile station, the mobile station determines that the zone is moving before the level of the zone boundary, so when traffic is concentrated in a specific area,
Mobile station communications can be distributed in the peripheral zones.
For example, when traffic is concentrated in the zone of the base station in which the mobile station is located and the received electric field level from one neighboring base station is higher than that of another neighboring base station, the mobile station is in the zone of the neighboring base station. Move to the zone.

On the contrary, when a large value is notified to the mobile station, the zone transition is not judged even if the zone boundary is crossed to some extent. Therefore, when the traffic in the surrounding area is large and the traffic in the local area is small, the surrounding area is small. It is possible to suppress channel switching to the base station.

In the above embodiment, the case where the base station notifies the mobile station of the correction value and the mobile station corrects the value of the received electric field level has been described as an example. It is also possible to notify the value of the electric field level and use the value as it is in the mobile station. Also, instead of notifying the receiving electric field level to the communicating base station after measuring the receiving electric field level to all communicating base stations and peripheral base stations, if the receiving electric field level from the communicating base station is measured, The present invention can be similarly implemented by notifying the base station during communication immediately and then measuring the received electric field level from the peripheral base stations.

Further, although the case where the number of frequency bands is 2 has been described, the present invention can be similarly implemented when the number of frequency bands is 3 or more.

[0029]

As described above, when the mobile station is communicating in a certain frequency band, the mobile communication device of the present invention changes the electric field level received from the peripheral base station to a frequency band different from that frequency band. The received electric field level from the communicating base station is corrected by the difference in the frequency band. Thereby, accurate zone determination can be performed.

Further, since it is sufficient to measure the electric field level received from the peripheral base station for one frequency band, considering that the level must be measured for each frequency band, it is necessary to receive twice as many frames. It is possible to reduce the power consumption of mobile stations.

Further, by manipulating the correction value notified to the mobile station, it is possible to prevent the traffic distribution in the area from concentrating on a specific zone, and to reduce the call loss rate.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a mobile wireless device implementing the present invention, and is a diagram showing an arrangement of a mobile station and a base station which are in communication with each other and base stations around the base station.

FIG. 2 is a diagram in which a part of the configuration of FIG. 1 is rewritten.

FIG. 3 is a diagram showing a relationship between a mobile station and a base station.

FIG. 4 is a diagram showing a flow of control of a base station and a mobile station for the mobile station to determine a visited zone.

FIG. 5 is a block diagram showing an example of a mobile station.

6A and 6B are diagrams for explaining a received electric field level measuring operation in a mobile station, wherein FIG. 6A shows a received signal of the mobile station, and FIG. 6B shows a received frequency of the mobile station.

FIG. 7 is a diagram for explaining the relationship between the level measurement result at the mobile station and the correction operation.

FIG. 8 is a diagram showing an operation sequence between a mobile station and a base station.

[Explanation of symbols]

 11 to 17 base station 20, 30 mobile station 21 modulation circuit 22 demodulation circuit 23 frequency synthesizer 24 reception level measurement circuit 25 timing generation circuit 26 encoding circuit 27 control circuit 28 decoding circuit

Claims (3)

[Claims] 1. A plurality of radio base stations arranged in a service area, and a mobile station capable of communicating with each radio base station by a time division multiple access method, wherein the mobile station is a radio base station in communication. A means for receiving the respective radio signals from the station and its surrounding radio base stations and measuring the received electric field level, and a means for comparing the measured received electric field levels and determining the zone in which the user is located. In a mobile communication device including, the plurality of radio base stations are configured to perform transmission and reception of a control channel and a communication channel respectively in a plurality of frequency bands, the mobile station selects one of the plurality of frequency bands as a transmission and reception frequency Control means and the selecting means so that the received signal is supplied to the measuring means in the time slot during communication, and the time slot not used for communication is Control unit that selects a frequency band that is not used for the communication and supplies the radio signal from the peripheral radio base station to the measuring unit, and the measurement of the electric field level received from the radio base station of the communication partner. A measurement value notifying means for notifying the value to the radio base station, wherein the radio base station obtains a correction value for the measurement value notified from the mobile station based on the difference in the frequency band, and the correction value. Correction value notifying means for notifying the mobile station, and the judging means compares the reception electric field level corrected by the correction value from the correction value notifying means with the reception electric field level from a peripheral wireless base station. A mobile communication device comprising: 2. The mobile communication device according to claim 1, wherein the plurality of frequency bands are 800 MHz and 1.5 GHz bands. 3. A means for communicating with a radio base station by a time division multiple access system, and a radio field received by receiving radio signals from the radio base station in communication and the radio base stations in the vicinity thereof. In a mobile station device having means for measuring the level and means for comparing the measured received electric field level to determine the zone in which it is located, means for selecting one of a plurality of frequency bands as a transmission / reception frequency And controlling the selecting means to supply the received signal to the measuring means in the time slot during communication, and select the frequency band not used in the communication in the time slot not used for communication. A control means for supplying the measuring means with a radio signal from a peripheral radio base station and a measurement value of the electric field level received from the radio base station of the communication partner are notified to the radio base station. A mobile station, comprising: measurement value notifying means, wherein the determining means includes means for comparing a received electric field level corrected by a correction value from the base station with a received electric field level from a peripheral wireless base station. apparatus.