WO2001033248A1

WO2001033248A1 - Mobile communication system

Info

Publication number: WO2001033248A1
Application number: PCT/JP2000/007678
Authority: WO
Inventors: Kiyoshi Nomura
Original assignee: Matsushita Electric Industrial Co., Ltd.
Priority date: 1999-11-02
Filing date: 2000-11-01
Publication date: 2001-05-10
Also published as: AU1052401A

Abstract

A mobile communication system has a mobile radio terminal which receives a signal transmitted from a communication object base station device and ordering the calculation of position information and calculate the arrival time differences between the timing signal transmitted from a reference base station device out of base stations including the communication object base station and the timing signals transmitted from the other base station devices and transmits the calculated arrival time differences to the communication object base station device.

Description

Description Mobile communication technology

The present invention relates to a mobile communication system that handles mobile wireless terminals such as mobile phones and PHS terminals, and more particularly to a mobile communication system that has a function of detecting the position of a mobile wireless terminal. Background art

In recent years, as the number of users of mobile communication services has increased, it has become necessary to detect the position of a mobile wireless terminal such as a mobile phone * PHS terminal. To date, several methods for detecting the position of a mobile radio terminal have been proposed and put into practical use. Among these methods, a method that has high accuracy in detecting the position of a mobile radio terminal and is relatively easy to realize in an existing mobile communication system is disclosed in, for example, Japanese Patent Application Laid-Open No. 7-181242. Are disclosed.

The method disclosed in the above-mentioned publication is used in a mobile communication system in which a communication of a DCMA method is performed between a mobile radio terminal and a plurality of base stations. In this mobile communication system (hereinafter referred to as “first mobile communication system”), the mobile radio terminal determines the time (propagation delay time) until the transmission signal of each base station reaches the mobile radio terminal. The position of the own station is calculated using three elements including a difference, a difference in transmission timing between transmission signals of each base station, and information on the position of each base station. Hereinafter, the difference in time required for the transmission signal of each base station to reach the mobile radio terminal is referred to as “propagation delay time difference”.

The propagation delay time difference among the above three factors is calculated by the mobile radio terminal. Information on the difference in transmission timing and the position of each base station among the above three elements is transmitted from the base station to the mobile radio terminal via a predetermined radio channel. Will be notified.

In this mobile communication system, the mobile radio terminal communicates via an access channel when the mobile radio terminal is in a standby state, and a traffic channel used for transmitting voice information when the mobile radio terminal is in a call state. The information on the calculated position is transmitted to the base station or the management station dedicated to position detection via.

However, in the first mobile radio system described above, a part of the communication resources used for communication from the base station to the mobile radio terminal is used for communication of the above-described transmission timing difference and information on the position of each base station. Need to be assigned to

Furthermore, in this mobile communication system, the mobile radio terminal calculates the position using the above three elements, so that the operation rate of CPU increases and an extra memory is required. For this reason, there is a problem that the power consumption and the device size of the mobile radio terminal increase.

In order to solve such a problem, the present inventors notify the propagation delay time difference calculated by the mobile radio terminal to the base station, and the base station notifies the propagation delay time difference notified from the mobile radio terminal to the position calculation station. Notifying, and the position calculating station detects the position of the mobile radio terminal using the difference in the transmission timing, the information on the position of each base station, and the propagation delay time notified from the base station. System (hereinafter referred to as “second mobile communication system”). This invention is disclosed in Japanese Patent Application Laid-Open No. H11-12526332.

However, the above-mentioned conventional mobile communication system has the following problems. First, in both the first mobile communication system and the second mobile communication system described above, the mobile radio terminal receives transmission signals (spread spectrum signals) from a plurality of base stations, and In order to detect the position of the station, a difference in time required for the transmission signal of the base station to reach the mobile radio terminal, that is, a propagation delay time difference, is calculated using the received transmission signals. When calculating the propagation delay time difference, the mobile radio terminal needs to operate a circuit (including a digital signal processor) for calculating the propagation delay time difference. Therefore, if the mobile wireless terminal frequently calculates the propagation delay time difference, the operating rate of the circuit increases and an extra memory is required, so that more power is consumed.

Therefore, the operating time (ie, standby time and talk time) of a mobile wireless terminal using a small battery as a power source is significantly reduced. In order to improve the operation time of the mobile wireless terminal, it is conceivable to install a larger battery in the mobile wireless terminal. In this case, it is difficult to reduce the size of the mobile wireless terminal.

As described above, in the conventional mobile communication system, calculating the propagation delay time difference required for detecting the position of the mobile radio terminal prevents the miniaturization of the mobile radio terminal and prolongation of the standby time and the talk time. It is a factor.

Second, the position of the mobile radio terminal may be detected even in a standby state. In this case, in the first mobile communication system, information on the position of the mobile radio terminal is transmitted from the mobile radio terminal to the base station via an access channel. This greatly increases the traffic on the access channel used only for location registration and outgoing traffic. Such an increase in traffic may cause a shortage of access channel capacity, and may increase a processing load on a base station receiving the information on the above-mentioned location or a management station dedicated to location detection. . In the second mobile communication system, not the information on the position of the mobile radio terminal but the propagation delay time difference is transmitted from the mobile radio terminal to the base station via a predetermined radio channel. Therefore, there is a possibility that a similar increase in traffic occurs in the predetermined wireless channel. Third, in the first mobile communication system (the second mobile communication system), the mobile radio terminal transmits more information on the position (propagation delay time difference) to the base station more frequently. Power will be consumed. This allows The operating time of a mobile wireless terminal that mainly uses a small battery as a power source is significantly shortened, which makes it difficult to reduce the size of the mobile wireless terminal, make the standby time longer, and increase the talk time. Disclosure of the invention

An object of the present invention is to provide a mobile communication system that reduces the power consumption and size of a mobile wireless terminal and that reduces traffic on a wireless channel.

The purpose is that only the mobile radio terminal instructed to calculate the position information (that is, the mobile radio terminal that has been requested to detect the position information) has the propagation delay time difference (arrival time) required to calculate the position information of this mobile radio terminal. Is calculated and transmitted to the base station. More specifically, according to the present invention, among mobile radio terminals instructed to calculate position information, only a moving mobile radio terminal calculates a propagation delay time difference and transmits it to a base station. Achieved. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a block diagram showing a configuration of a mobile communication system according to a first embodiment of the present invention;

FIG. 2 is a block diagram showing a configuration of a base station in the mobile communication system according to the first embodiment of the present invention;

FIG. 3 is a block diagram showing a configuration of a mobile radio terminal in the mobile communication system according to the first embodiment of the present invention;

FIG. 4 is a block diagram showing a configuration of a position calculating station in the mobile communication system according to the first embodiment of the present invention;

FIG. 5 is a schematic diagram showing an example of a frame format of a paging channel transmitted by a base station in the mobile communication system according to the first embodiment of the present invention; FIG. 6 is a block diagram showing a configuration of a mobile radio terminal in a mobile communication system according to a second embodiment of the present invention;

Hereinafter, the best mode for carrying out the invention will be described with reference to the accompanying drawings.

(Embodiment 1)

In the present embodiment, a case where the position of a mobile radio terminal in a standby state is detected will be described with reference to FIG. FIG. 1 is a block diagram showing a configuration of the mobile communication system according to the first embodiment of the present invention.

As shown in FIG. 1, the mobile communication system according to the present embodiment includes a mobile radio terminal 5, base stations 1 to 4 around the mobile radio terminal 5, and base stations 1 to 4, respectively. And a position calculation station 6 connected via wired lines 21 to 24. In the present embodiment, for simplicity of description, it is assumed that mobile radio terminal 5 performs normal radio communication with base station 1 (that is, the base station to be communicated with is base station 1).

The base stations 1 to 4 transmit timing signals 11 to 14, respectively. These timing signals are signals used by the mobile radio terminal 5 for the purpose of calculating a time difference (that is, arrival time difference) until the transmission signal of each base station reaches the mobile radio terminal 5. . Note that, in the present embodiment, an example will be described in which a signal transmitted via a perch channel (hereinafter referred to as a “perch channel signal”) is used as a timing signal. The perch channel signal transmitted by each base station is spread by a base station-specific perch channel spreading code.

As the timing signal, any signal other than the perch channel signal can be used as long as the condition that the mobile radio terminal 5 can calculate the arrival time difference is satisfied. For example, indicate the time actually transmitted by the base station. If the signal containing the timing information is transmitted by the base station as a timing signal, the mobile radio terminal 5 determines the time when the timing signal was received and the information indicating the time included in the timing signal. By using this, the time of arrival for this base station can be calculated. Thereby, the mobile radio terminal 5 can calculate the arrival time difference using the timing signal transmitted by each base station.

Further, the base stations 1 to 4 transmit a position information signal (ie, a signal including information for instructing calculation of position information) to a mobile wireless terminal that is performing normal wireless communication with the base station. These position information signals are transmitted to the mobile radio terminal 5 as position information (specifically, information necessary for calculating the position of the mobile radio terminal 5, that is, the arrival time difference at the mobile radio terminal 5). This signal is used for the purpose of instructing the calculation of. In the present embodiment, an example will be described in which a signal transmitted via a paging channel (hereinafter, referred to as a “paging channel signal”) is used as a position information signal. The paging channel signal transmitted by each base station is spread by a base station-specific paging channel spreading code.

Here, the mobile radio terminal 5 performs normal radio communication with the base station 1 (that is, the base station 1 is a communication target base station for the mobile radio terminal 5). The figure shows that only the base station 1 transmits the paging channel signal 15 to the mobile radio terminal 5. Although not shown in FIG. 1, base stations 2 to 4 also transmit paging channel signals to mobile radio terminals that are performing radio communication with the base stations.

FIG. 2 is a block diagram showing a configuration of a base station in the mobile communication system according to the first embodiment of the present invention. As shown in FIG. 2, the base stations 1 to 4 include a timing signal transmitting unit 31 for transmitting a timing signal (perch channel signal) to the mobile radio terminal 5 via the antenna 30, The mobile radio terminal 5 uses the signal transmitted from the antenna 5 and received via the antenna 30. A signal transfer unit 35 that extracts information about the calculated arrival time difference and transfers it to the transmission / reception unit 34, and a paging channel transmission unit that transmits a paging channel signal (position information signal) to the mobile radio terminal 5. A transmission / reception unit 3 for transmitting the information transferred by the signal transmission unit 3 5 and the timing of the timing signal transmitted by the timing signal transmission unit 31 to the position calculation station 6 via the wired line 37. And 4.

FIG. 3 is a block diagram showing a configuration of a mobile radio terminal in the mobile communication system according to the first embodiment of the present invention. As shown in FIG. 3, the mobile radio terminal 5 includes a paging channel receiver 44 for extracting a paging channel signal (position information signal) from a signal (received signal) received by the antenna 40, and a paging channel. The contents of the base channel signal extracted by the channel receiving unit 44 are analyzed, and each unit (the timing signal receiving unit 41, the calculating unit 42, and the comparing unit 46) of the mobile radio terminal 5 is analyzed according to the analysis result. An analysis section 47 for controlling; a timing signal reception section 41 for extracting timing signals 11 to 14 constantly transmitted by the base stations 1 to 4 from signals (reception signals) received by the antenna 40; A calculation unit 42 for calculating the arrival time difference between the timing signals 11 to 14 extracted by the timing signal reception unit 41; and a storage unit 45 for storing the arrival time difference calculated by the calculation unit 42. , Calculation The difference between the current arrival time difference (current arrival time difference) calculated by the unit 42 and the arrival time difference (previous arrival time difference) stored by the storage unit 45 is calculated, and the calculated difference is compared with a predetermined value. And a transmitting section 43 for transmitting the arrival time difference calculated by the calculating section 42 to the base station 1 in accordance with the result of the comparison in the comparing section 46.

FIG. 4 is a block diagram showing a configuration of a position calculating station in the mobile communication system according to the first embodiment of the present invention. As shown in FIG. 4, the position calculation station 6 includes a wired line 37 connected to each of the base stations 1 to 4 and a signal obtained through the wired line 37 (for example, an information signal such as voice and an arrival time difference to be described later). Receiving information 51) and information on the positions of base stations 1 to 4 (hereinafter referred to as “position information”). Location information ". ), The arrival time difference at the mobile radio terminal 5 received by the receiving unit 51, the position information of the base stations 1 to 4 stored in the storage unit 52, and the base station And a position information calculator 53 that calculates the position of the mobile radio terminal 5 using the difference in transmission timing between the timing signals transmitted by 1 to 4.

Next, the operation of the mobile communication system according to the present embodiment will be described in detail with reference to FIG. 5 in addition to FIGS. FIG. 5 is a schematic diagram illustrating an example of a frame format of a base channel transmitted by the base station in the mobile communication system according to the first embodiment of the present invention. The paging channel is a channel used for a mobile radio terminal in a standby state to intermittently receive information from a base station (intermittent reception). The details of this paging channel are as follows.

Each mobile radio terminal that intermittently receives from the base station 1 is assigned one of a plurality of groups prepared in advance as a group to which the mobile terminal belongs. That is, the mobile radio terminals that receive intermittently from the base station 1 are grouped. The base station 1 divides each unit frame into a predetermined number of time slots, and allocates a group to which information is transmitted to each time slot. Further, base station 1 transmits information on the predetermined group using a time slot to which the predetermined group is assigned. Each mobile radio terminal intermittently receiving from the base station 1 receives only the time slot corresponding to the group to which the mobile terminal belongs.

Specifically, referring to FIG. 5, each unit frame (for example, first to third frames) is divided into a predetermined number (for example, 5) of time slots. For each time slot, a group to which information is to be transmitted (for example, a first group and a second group) is assigned. For example, the first group is assigned to time slots 6 1—1, 6 2—2 and 6 3—3, and the second group is assigned to time slots 6 2—1 and 6 3—2. Assigned.

Information on each group (mobile radio terminals belonging to) is provided by the control unit and The data section 4 is included. The control unit in the information on the first group is transmitted in time slot 61-1 among the time slots to which the first group is assigned, and the data unit 1 in the information on the first group is assigned to the first group. The data part 2 of the information about the first group is transmitted in the time slot 63-2 of the time slots to which the first group is assigned. . Details of the information for each group are as follows. That is, the information on each group includes a control unit and a plurality of data units. The control section includes data indicating whether or not data sections 1 to 4 contain valid data (0: no valid data, 01: incoming call instruction, 10: position information calculation instruction, 1 1: Position information calculation stop instruction) is set. The data sections 1 to 4 contain information indicating the number of the terminal to be controlled by the control section.

The mobile radio terminal that has received the control unit indicating “0 0 (no valid data)” does not receive the data units 1 to 4 for the group to which the mobile terminal belongs. The mobile radio terminal stops the reception operation until a time slot in a predetermined frame transmitted by the next control unit for the group to which the mobile radio terminal belongs.

The mobile radio terminal that has received the control unit indicating “01 (incoming call instruction)” first receives the data units 1 to 4 for the group to which the terminal belongs, transmitted from the next frame onward. Further, when the received data portions 1 to 4 include information indicating the own terminal, the mobile radio terminal starts a call reception operation and then starts a telephone call (normal communication).

The mobile radio terminal that has received the control unit indicating “10 (location information calculation instruction)” first receives the control unit indicating “01 (incoming instruction)” in the same manner as when the control unit indicates the next frame. Receives the transmitted data parts 1 to 4 for the group to which the terminal belongs. Further, when the received data portions 1 to 4 include information indicating the own terminal, the mobile wireless terminal calculates the arrival time difference. The details of the calculation of the arrival time difference will be described later. This “10 (position information calculation instruction)” May be transmitted to a mobile wireless terminal (for example, a mobile wireless terminal owned by a wandering elderly person or the like) for which location information is required at regular time intervals. Alternatively, it may be transmitted a predetermined number of times.

The mobile radio terminal that has received the control unit indicating "1 1 (position information calculation stop instruction)" first transmits the control unit after the next frame in the same manner as when the control unit indicates "01 (incoming instruction)". It receives the data for the group to which the terminal belongs. Furthermore, when the received data portions 1 to 4 include information indicating the own terminal, the mobile radio terminal stops calculating the arrival time difference. The above is the details of the paging channel.

First, the operation of the mobile wireless terminal 5 will be described. Referring to FIG. 3, in antenna 40, mainly evening signal 11 to 14 transmitted by each of base stations 1 to 4 and paging channel signal transmitted by base station 1 Are received at the same time.

The signal (received signal) received by antenna 40 is sent to paging channel receiving section 44 and timing signal receiving section 41. The paging channel receiving section 44 performs despreading processing on the received signal from the antenna 40 using the paging channel spreading code assigned to the base station 1, thereby converting the paging channel signal. Is extracted. The extracted paging channel signal is sent to analysis section 47.

The operation of paging channel signal receiving section 44 is performed when base station 1 transmits a control section (see FIG. 5) for the group to which the own terminal belongs.

In addition, the operation of paging channel signal receiving section 44 as described above is performed when base station 1 is transmitting data sections 1 to 4 (see FIG. 5) for the group to which the own terminal belongs. However, at this time, the operation of the paging channel signal receiving unit 44 is performed under the control of the analyzing unit 47 that has analyzed the contents of the control unit. The analysis section 47 analyzes the contents of the paging channel signal extracted by the paging channel reception section 44 (specifically, the control section for the group to which the terminal belongs). According to the result of this analysis, first, the paging channel receiving section 44 is controlled by the analyzing section 47. That is, when the control unit in the extracted paging channel signal is any of “01”, “10”, and “11”, the data units 1 to 4 for the group to which the own terminal belongs belong to the base station. Since it is transmitted by 1, the paging channel receiving section 44 is controlled by the analyzing section 47 so as to extract the paging channel at the timing when the data sections 1 to 4 are received. As a result, the contents of the paging channel signal extracted by the paging channel receiving unit 44 (specifically, the data units 1 to 4 of the group to which the own terminal belongs) are input to the analyzing unit 47. .

Further, the analyzing section 47 controls the timing signal receiving section 41, the calculating section 42, and the comparing section 46 according to the results of the analysis of the analyzing section and the data sections 1 to 4. That is, the control unit in the extracted paging channel signal indicates “10 (location information calculation instruction)”, and one of the demultiplexing units 1 to 4 in the extracted paging channel signal indicates its own terminal. The analysis unit 47 activates the timing signal reception unit 41, the calculation unit 42, and the comparison unit 46 only when the information indicating the following is included. As described above, the base station 1 sends a control unit that indicates “10 (location information calculation instruction)” to the mobile radio terminal that needs location information at regular time intervals or a predetermined number of times. Send. Therefore, each time the own terminal receives the position information calculation instruction from the base station 1 and each of the data sections 1 to 4 includes information indicating the own terminal, the analysis section 47 executes Is activated.

When the control unit in the extracted paging channel signal is “0 0 (no valid data)” or “01 (incoming instruction)”, the above units are not activated by the analysis unit 47. The control unit in the extracted paging channel signal is “11 (location information calculation stop instruction)”, and the extracted paging channel signal is If the information indicating the own terminal is included in any of the data sections 1 to 4 in the data channel signal (in this case, the control section was previously “10” and the data section 1 to 4 (It goes without saying that the above-described units have been activated because the information indicating the terminal is included.) The analysis unit 47 stops the activation of the above units.

The control unit in the extracted paging channel signal is “01 (incoming call instruction)”, and information indicating the own terminal is included in any of the data units 1 to 4 in the extracted paging channel signal. In such a case, the above-described units may be activated by the analysis unit 47. However, in this case, power consumption may increase due to frequent processing by the above-described units. Therefore, the control unit in the extracted paging channel signal is “10”, and information indicating the own terminal is included in any of the data units 1 to 4 in the extracted paging channel signal. It is preferable that the above-described units are started by the analysis unit 47 only when there is an error.

When each of the above units is started by the analysis unit 47, the following processing is performed. That is, the timing signal receiving unit 41 performs despreading processing on the received signal from the antenna 40 using a spreading code for a perch channel unique to each of the base stations 1 to 4. As a result, evening signals 11 to 14 transmitted by base stations 1 to 4 are extracted. Each of the extracted timing signals is sent to the calculation unit 42.

The calculating unit 42 calculates the arrival time difference between the timing signals using each timing signal extracted by the timing signal receiving unit 41. That is, the arrival time difference between the timing signals transmitted by the reference base stations in all the base stations (base stations 1 to 4) and the timing signals transmitted by each base station other than the reference base station is calculated. More specifically, when the evening signal 11 transmitted by the base station 1 is used as a reference (that is, the base station 1 is used as a reference base station), the timing signal 11 and the timing signals 12 to 14 are used. Arrival time difference between (t pl2, tpl3, tp14) are calculated. Note that any of the base stations 1 to 4 may be selected as the reference base station. The calculated arrival time difference is sent to the comparison unit 46 and the accumulation unit 45.

The storage unit 45 stores the arrival time difference calculated by the calculation unit 42 as a current arrival time difference (current arrival time difference). The comparison unit 46 compares the arrival time difference currently calculated by the calculation unit 42 (current arrival time difference) with the arrival time difference previously calculated by the calculation unit 42 and stored in the storage unit 45 (previous arrival time difference). ) The difference between and is calculated. Further, the calculated difference is compared with a predetermined value. If the calculated difference is equal to or larger than the predetermined value, the comparing unit 46 determines that the mobile wireless terminal 5 has moved from the previous position, and transfers the currently calculated arrival time difference to the transmitting unit 43. Is done. Conversely, if the calculated difference is less than the predetermined value, the comparing unit 46 determines that the mobile wireless terminal 5 is at the previous position, and transfers the arrival time difference to the transmitting unit 43. Not done.

The predetermined value is set by the base station 1 and received by the mobile radio terminal 5 via a channel such as an access channel. Further, the predetermined value is set by the base station 1 so as to be a value corresponding to the required accuracy of position detection. Naturally, since there are a plurality of mobile radio terminals that perform radio communication with the base station 1, the above-mentioned predetermined value is set by the base station 1 for each mobile radio terminal.

Note that, in the present embodiment, the mobile radio terminal transmits only when the base station issues a position information calculation instruction and the mobile terminal is not moving (ie, the arrival time difference is equal to or greater than a predetermined value). The case where information indicating the arrival time difference is transmitted to the base station has been described. However, the present invention is not limited to this, and when the mobile radio terminal issues a position information calculation instruction from the base station irrespective of the movement of its own terminal, information indicating the arrival time difference with respect to the base station is provided. It can be applied to the transmission of In this case, the base station reliably receives the arrival time difference at the mobile radio terminal only from the mobile radio terminal that needs position detection. Therefore, the current position of the mobile radio terminal can be reliably detected. In this way, by setting a predetermined value for each mobile radio terminal according to the required accuracy of position detection, the frequency of transmission of position information (arrival time difference) by the mobile radio terminal, which may have low detection accuracy, is suppressed. Therefore, the power consumption of the mobile radio terminal can be reduced. The setting of the predetermined value is performed not only by the base station 1 but also in the base stations 2 to 4.

The arrival time difference transferred from the comparing section 46 is transmitted to the base station 1 through the antenna 40 by the transmitting section 43. Here, since the own terminal is in the standby state, the arrival time difference is transmitted to the base station 1 while being superimposed on the channel used in the standby state (the access channel in the present embodiment). That is, a signal including information indicating the arrival time difference is transmitted from the base station 1 to the mobile wireless terminal 5 via the access channel. Hereinafter, a signal transmitted via the access channel is referred to as an “access channel signal”.

Next, the operation in base station 1 will be described. First, focusing on the transmission processing, the paging channel transmission unit 36 includes information about each group (for example, the control unit and the data transmission units 1 to 4) according to the frame format as shown in FIG. A signal is generated, and the signal is despread by a paging channel spreading code unique to base station 1 to generate a paging channel signal. The timing signal transmitting unit 31 generates a signal including information indicating the transmission timing of the timing signal transmitted by the own station (that is, information indicating the time at which the timing signal is actually transmitted) and the like. A timing signal (perch channel signal) is generated by being spread by a perch channel spreading code unique to station 1.

The generated paging channel signal and timing signal are multiplexed at the same time and transmitted via antenna 30. The signal transmitted in this manner is received by mobile radio terminal 5 described above. On the other hand, focusing on the reception processing, the access channel signal transmitted by the mobile radio terminal 5 described above is received via the antenna 30 and transmitted to the signal transfer unit 35. In the signal transfer section 35, information on the arrival time difference calculated by the mobile radio terminal 5 is extracted from the signal (received signal) received by the antenna 30.

Here, it goes without saying that the information on the arrival time difference calculated by the mobile radio terminal 5 is extracted from the received signal only when all of the following conditions are satisfied. That is, first, the first condition is that a position information calculation instruction is issued from the base station 1 to the mobile radio terminal 5 via the paging channel, and that the base station 1 That is, the position information calculation stop instruction is not issued through the paging channel. The second condition is that the mobile radio terminal 5 is moving (that is, it is recognized that the difference between the previous arrival time difference and the current arrival time difference is equal to or more than a predetermined value in the comparing unit 46 in FIG. 3). That is.

The information on the extracted arrival time difference is transmitted to the position calculating station 6 through the wired line 37 together with the information on the transmission timing of the timing signal transmitted by the own station by the transmitting section 34.

Although the operation of the base station has been described using the base station 1 as an example, the base stations 2 to 4 have the same configuration as the base station 1, and are connected between the mobile station and a mobile radio terminal that performs radio communication. Performs the same transmission processing and reception processing as described above.

Next, the operation of the position calculation station will be described. Information on the transmission timing of the timing signals of the base stations 1 to 4 is sent to the receiving unit 51 via the wired line 37. Further, to the receiving section 51, information on the calculated arrival time difference is transmitted from the base station 1 to the mobile wireless terminal 5 via the wired line 37. These pieces of information are sent from the receiving unit 51 to the position information calculating unit 53.

The storage unit 52 stores the position information of the base stations 1 to 4. Specifically, the storage unit 52 stores information in which the positions of the base stations 1 to 4 are represented on a three-dimensional axis. Have been. In the present embodiment, the position information of base stations 1 to 4 is respectively (X1, Υ1, Ζ1), (Χ2, Υ2, Ζ2), (Χ3, Υ3, Ζ3), (Χ4, Υ4, Ζ4). The position information of the base stations 1 to 4 stored in the storage unit 52 is sent to the position information calculation unit 53.

The position information calculation unit 53 uses the position information of the base stations 1 to 4, the transmission timings of the timing signals transmitted by the base stations 1 to 4, and the arrival time difference calculated by the mobile radio terminal 5 to perform a mobile operation. The position of the wireless terminal 5 is calculated. The calculation of the mobile wireless terminal can be realized, for example, by the method disclosed in Japanese Patent Laid-Open No. 11-252632 by the present inventor. The outline of this method is as follows.

That is, first, using the transmission timing of the timing signals transmitted by the base stations 1 to 4, the transmission timing between the timing signal of the reference base station and the timing signals of the base stations other than the reference base station is determined. The difference is calculated. The reference base station may be any one of all base stations. In the present embodiment, since base station 1 is the reference base station, the difference in transmission timing between the timing signal of base station 1 and the timing signals of base stations 2 to 4 (that is, tdl 2, tdl 3 , Td 14) are calculated. Furthermore, the position information of the base stations 1 to 4, the transmission timing difference between the timing signal of the base station 1 and the timing signal of the base stations 2 to 4, and the arrival time difference at the mobile radio terminal 5 are used. By solving the simultaneous equations, the position (X, Y, Z) of the mobile radio terminal 5 on the three-dimensional axis is calculated. The specific method of calculating the position is as disclosed in the above publication. Here, the method of calculating the position of the mobile radio terminal disclosed in the above publication is included.

In the mobile communication system having the above-described configuration, the base station transmits a signal (in other words, a signal instructing calculation of position information (arrival time difference) via a paging channel only to mobile radio terminals that need to be located. 10 (location information calculation instruction)), and if the location information of this mobile wireless terminal is no longer needed, A signal (ie, "11 (location information calculation stop instruction)" for instructing the mobile radio terminal to stop calculating the location information (arrival time difference) can be transmitted via the paging channel. As a result, the arrival time difference can be calculated by only the mobile radio terminals that need position detection among all the mobile radio terminals in the standby state, and can reach mobile radio terminals that do not need position detection. Since the time difference is not calculated, the power consumption of the mobile radio terminal can be kept low.

As described above, according to the mobile communication system according to the present embodiment, the mobile radio terminal receives the timing signal for position detection (specifically, receives the timing signal transmitted by each base station. The signal is extracted from the signal), the arrival time difference is calculated, and the calculated arrival time is not always transmitted to the base station, but only when a signal instructing to calculate the position information is received from the base station. Do. As a result, the power consumption of the mobile radio terminal can be kept low, and the traffic on the access channel can be reduced. In addition, the processing load on the base station and the position calculation station that receives the position information (arrival time difference) from the mobile radio terminal (for example, the load in the transmission / reception processing of the arrival time difference and the load in calculating the position of the mobile radio terminal) is reduced. You can also.

Further, according to the mobile communication system according to the present embodiment, the mobile radio terminal receives the timing signal for position detection, calculates the arrival time difference, and transmits the calculated arrival time to the base station. However, instead of performing this operation all the time, a signal for instructing calculation of position information is received from the base station and only when the own terminal moves, so that the power consumption of the mobile radio terminal can be further reduced. At the same time, traffic on the access channel can be further reduced. Further, the processing load on the base station and the position calculation station that receive the position information (arrival time difference) from the mobile radio terminal can be further reduced.

Further, according to the mobile communication system according to the present embodiment, since it is possible to suppress the power consumption of the mobile radio terminal, it is possible to use the mobile radio terminal. A small battery with a small capacity can be selected as the battery to be used (including a rechargeable battery). As a result, the size of the mobile radio terminal can be reduced.

Also, in the present embodiment, a paging channel is used as a channel for transmitting a signal instructing the mobile radio terminal to calculate position information (arrival time difference) in order to take advantage of the following. Was explained.

(1) In PDC and W_CDM, the channel used for intermittent reception by a mobile radio terminal in a standby state shall be a paging channel.

(2) The paging channel includes the concept of grouping, and the mobile radio terminal can use the paging channel to perform intermittent reception, thereby reducing the power consumption of the mobile radio terminal.

(3) In the paging channel, there is a field for transmitting the number of the terminal to be called in order for the mobile radio terminal to perform a call receiving operation. Therefore, this field can include a signal instructing calculation of position information.

However, the present invention is also applicable to a case where a channel other than a paging channel is used as a channel for transmitting a signal instructing calculation of position information. Specifically, any channel that satisfies the following conditions can be used as a channel for transmitting a signal for instructing calculation of position information. In other words, (1) All mobile radio terminals that perform intermittent reception with the base station must be able to receive a signal instructing the calculation of location information in common (a common channel). (2) The channel must be able to transmit signals to start and stop calculating position information. (3) The channel must be capable of transmitting a signal indicating the mobile radio terminal from which position information calculation is started and stopped.

Here, the paging channel is a channel that satisfies the above conditions (1) to (3) and can instruct a mobile radio terminal that performs intermittent reception to perform an incoming call operation. Therefore, when the paging channel is adopted, the mobile radio terminal only performs the intermittent reception via the paging channel and waits. It is possible to shift from the receiving state to the incoming call operation, and to start or stop the calculation of the position information. By this means, receiving a signal indicating start or stop of calculation of position information and receiving a signal indicating transition from a standby state to an incoming call operation can be realized by receiving one channel. . Therefore, the number of required radio channels can be reduced, the configuration of the receiving unit of the mobile radio terminal can be simplified, and the power consumption of the mobile radio terminal can be suppressed.

As described above, according to the mobile communication system according to the present embodiment, it is possible to reduce the power consumption and the size of the mobile radio terminal, and to reduce the traffic on the radio channel.

(Embodiment 2)

In the present embodiment, the difference between the current reception level and the previous reception level of the signal transmitted from the base station among the mobile radio terminals that have received the signal instructing the calculation of the position information in Embodiment 1 is described. A case will be described with reference to FIG. 6 in which only mobile radio terminals having a value equal to or greater than a predetermined value calculate arrival time differences and transmit the difference to the base station. FIG. 6 is a block diagram showing a configuration of a mobile radio terminal in the mobile communication system according to the second embodiment of the present invention. Note that the same components as those in the first embodiment (FIG. 3) in FIG. 6 are denoted by the same reference numerals as those in FIG. 3, and detailed description is omitted.

In FIG. 6, the analysis unit 70 does not control each unit in accordance with the analysis result, but sends the analysis result to a comparison unit 73 described later, except for the analysis unit 4 in the first embodiment. It has the same configuration as 7. The reception level detection section 71 detects the reception level of the paging signal extracted by the paging channel signal reception section 44 at predetermined time intervals, and sends the detection result to the storage section 72 and the comparison section 73. The storage unit 72 stores the reception level of the paging signal detected by the reception level detection unit 71, and sends the storage result to the comparison unit 73. The comparison unit 73 performs the following operation according to the analysis result of the analysis unit 70. That is, the comparison unit 73 calculates the difference between the current paging channel reception level (current reception level) and the previously detected paging channel reception level (previous reception level), and compares the calculated difference with a predetermined value. Compare with value. Further, comparing section 73 activates timing signal receiving section 41 and calculating section 74 only when the calculated difference is equal to or greater than a predetermined value.

Calculating section 74 has the same configuration as calculating section 42 in Embodiment 1 except that the calculated arrival time difference is transmitted to transmitting section 43.

Next, the operation of the mobile radio terminal having the above configuration will be described focusing on only the differences from the first embodiment. The paging channel signal extracted by paging channel reception section 44 is sent to analysis section 70 and reception level detection section 71. The reception level detector 71 detects the reception level of the extracted paging channel signal at predetermined time intervals. The reception level of the detected paging channel signal is stored in storage section 72. Analysis section 70 analyzes the contents of the paging channel signal (control section or control section and data sections 1 to 4), similarly to analysis section 47 in the first embodiment. The analysis result is sent to the comparison unit 73. The extraction of the paging channel signal in paging channel receiving section 44 (extraction of data sections 1 to 4 when the control section is “01” “10” “11”) is the same as that of the first embodiment. Similarly, it goes without saying that the control is performed by the analysis unit 70.

In comparison section 73, the control section in the paging channel signal is “10 (position information calculation instruction)”, and any of the data sections to 4 in the paging channel signal includes information indicating its own terminal. If there is, first, the difference between the current reception level of the paging channel signal detected by the reception level detection unit 71 and the previous reception level of the paging channel signal stored in the storage unit 72 is calculated. Further, the calculated difference is compared with a predetermined value. Note that the predetermined value is different from the predetermined value used by the comparing unit 46 in the first embodiment. It can be set in a similar way.

If the calculated difference is smaller than the predetermined value, it is recognized that the own terminal has not moved, and the comparing section 73 does not activate the timing signal receiving section 41 and the calculating section 74. Conversely, if the calculated difference is equal to or greater than the predetermined value, it is recognized that the own terminal is moving, and the comparing unit 73 activates the timing signal receiving unit 41 and the calculating unit 74. .

The processing in the timing signal receiving unit 41 and the calculating unit 74 is the same as that in the first embodiment, and thus detailed description is omitted. However, the arrival time difference calculated by the calculation unit 74 is transmitted by the direct transmission unit 43 via the antenna 40.

In this embodiment, a case has been described in which a change in the reception level of the paging channel is used as an index indicating the movement state of the mobile radio terminal. However, the reception level of any signal transmitted by the base station is described. The movement state of the mobile radio terminal may be recognized based on the change. Specifically, it is preferable to use a signal whose transmission level is always constant among the signals transmitted from the base station. However, if the transmission level is reported to the mobile radio terminal, the mobile radio terminal can recognize the relative change in the reception level, so that the transmission level of the signal transmitted from the base station is constant. It is also possible to use signals that are not. Furthermore, in the present embodiment, the mobile radio terminal detects the movement state of its own terminal based on a change in the reception level of a signal transmitted by the base station to be communicated (base station 1 in FIG. 1). However, if the above-mentioned method is adopted, the base station based on the reception level of the signal transmitted by the base station (the base stations 2 to 4 in FIG. 1) other than the base station to be communicated with will be described. It is also possible to detect the moving state of the terminal.

As described above, according to the mobile communication system according to the present embodiment, among the mobile radio terminals that have received the signal instructing the calculation of the position information, the current reception level and the previous reception level of the signal transmitted from the base station are determined. Mobile wireless terminal whose difference is greater than or equal to a predetermined value Only the end calculates the arrival time difference and sends it to the base station. As a result, the power consumption of the mobile radio terminal can be reduced, and the traffic on the access channel can be reduced. Further, the processing load on the base station and the position calculation station that receive the position information (arrival time difference) from the mobile radio terminal can be reduced. Further, as compared with Embodiment 1, although a configuration for detecting the reception level is required, the frequency of calculating the arrival time difference can be reduced, so that the power consumption of the mobile wireless terminal can be suppressed.

(Embodiment 3)

In the present embodiment, a case will be described in which the position of a mobile wireless terminal in a call is detected. In a mobile radio terminal in a call state, various processes are performed for the call, so that power consumption generally increases. When a signal instructing calculation of position information is received from a base station in a mobile wireless terminal in such a call state, processing for calculating an arrival time difference is performed in addition to processing for the call. Power consumption is further increased.

Specifically, when a signal instructing calculation of position information is received from the base station, the mobile radio terminal according to the first embodiment arrives at regular time intervals in order to detect the movement state of its own terminal. A time difference is calculated. By calculating the arrival time difference, the power consumption of the mobile radio terminal increases. However, the calculated arrival time difference is actually transmitted to the base station only when the difference from the previous arrival time difference is equal to or larger than a predetermined value. In other words, the arrival time difference that increases power consumption is calculated only to detect the moving state of the mobile radio terminal.

Therefore, in the present embodiment, attention is paid to the fact that the movement status of the mobile radio terminal can be detected by the base station using the arrival time difference or the reception level of the signal transmitted from the mobile radio terminal. That is, in this embodiment, the base station detects the arrival time (propagation delay) or the reception level of the signal transmitted by the mobile radio terminal, and detects the current arrival time among the mobile radio terminals requiring position detection. And before arrival Instructs only mobile radio terminals whose difference from the specified value exceeds a predetermined value, or only mobile radio terminals whose difference between the current reception level and the previous reception level exceeds a predetermined value to calculate position information. To send a signal.

Specifically, the base station calculates the arrival time (or reception level) of a signal (hereinafter referred to as a “traffic channel signal”) received via a traffic channel used for communication of information signals (voice and data). For each mobile radio terminal, it is detected and stored at specified time intervals.

When a base station detects a mobile radio terminal that needs to detect location information, the base station first determines the current arrival time (current reception level) and the previous arrival time (previous reception level) for this mobile radio terminal. The difference between is compared with a predetermined value. If the difference is equal to or greater than a predetermined value, it can be determined that the mobile radio terminal is moving, so the base station instructs the mobile radio terminal to calculate position information via a control channel or the like. To send a signal. Conversely, if the difference is less than the predetermined value, it can be determined that the mobile radio terminal has not moved, and the base station transmits a signal instructing the mobile radio terminal to calculate position information. do not do.

On the other hand, the mobile radio terminal transmits the signal by each base station only when the signal received via the control channel (hereinafter referred to as “control channel signal”) includes the signal instructing the calculation of the position information. The arrival time difference is calculated using the timing signal. Note that the calculation of the arrival time difference is the same as in the above-described embodiment, and a detailed description thereof will be omitted. Further, the mobile radio terminal transmits a traffic channel signal into which a signal relating to the calculated arrival time difference is inserted, to the base station.

The base station extracts information on the arrival time difference from the traffic channel signal and transmits the extracted information on the arrival time difference to the position calculation station. Subsequent operations performed by the position calculation station are the same as those in the above-described embodiment, and a detailed description thereof will be omitted.

Thus, according to the mobile communication system according to the present embodiment, When the line terminal is in a call state, the base station detects the arrival time (propagation delay) or reception level of the signal transmitted by the mobile wireless terminal, and the current arrival time of the mobile wireless terminal that needs position detection. For mobile radio terminals whose difference between the previous arrival level and the previous arrival level exceeds a predetermined value, or only for mobile radio terminals whose difference between the current reception level and the previous reception level exceeds a predetermined value, Transmit the signal instructing calculation. By this means, the mobile radio terminal for which position information detection is requested calculates the arrival time difference and transmits it to the base station only when the mobile terminal is surely moving. Therefore, it is possible to reduce the power consumption of the mobile radio terminal and reduce traffic on the traffic channel. Therefore, it is possible to keep the power consumption of the mobile radio terminal low, so it is possible to select a small battery with a small capacity (including a rechargeable battery) for use in this mobile radio terminal. it can. As a result, the size of the mobile radio terminal can be reduced.

In this embodiment, with the intention of minimizing the power consumption of the mobile radio terminal in the call state, the base station detects the movement state of the mobile radio terminal in the call state, and is requested to detect the position information. A case has been described in which a signal instructing calculation of position information is transmitted only to the mobile wireless terminal that is actually moving among the mobile wireless terminals.

However, the base station may transmit a signal instructing the calculation of the position information to all the mobile radio terminals requested to detect the position information. At this time, the mobile radio terminal that has received the signal for instructing the calculation of the position information may calculate the arrival time difference and transmit it to the base station, regardless of the moving state of the own terminal. Further, at this time, the mobile radio terminal that has received the signal instructing the calculation of the position information uses the change in the arrival time difference (the level of the received signal) as in Embodiment 1 (Embodiment 2). Only when the terminal is moving, the arrival time difference may be calculated and transmitted to the base station. Even in this case, the power consumption of the mobile radio terminal can be reduced as compared with the conventional method. In the present embodiment, the base station detects the moving state of the mobile radio terminal, and only the mobile radio terminal (and the mobile radio terminal that is actually moving) that has been requested to detect the position information receives the position information. Although the transmission of the signal instructing the calculation of the information has been described as being limited to communication with the mobile radio terminal in the call state, the mobile radio terminal in the standby state described in the first and second embodiments has been described. It is also possible to apply to the communication of. By this means, the power consumption of the mobile radio terminal in the standby state can be further reduced as compared to Embodiments 1 and 2.

In the above first to third embodiments, the case has been described where a position calculating station is provided to calculate the position of the mobile radio terminal. However, the position of the mobile radio terminal may be performed by any of the base stations. In this case, the base station that calculates the position of the mobile radio terminal (for example, base station 1 in FIG. 1) transmits the position information of a plurality of base stations (for example, base stations 1 to 4 in FIG. 1) and transmits the base station 1. It is necessary to recognize the difference between the timing signal transmitted and the timing signals transmitted by the base stations 2 to 4. The base station 1 can calculate the above difference using, for example, the received timing signals of the base stations 2 to 4. As described above, as a device for calculating the position of a mobile radio terminal, any of a base station and a position calculation station can be used. As described above, according to the present invention, only the mobile radio terminal instructed to calculate the position information calculates the propagation delay time difference required for calculating the position information of the mobile radio terminal, and transmits the difference to the base station. By transmitting, it is possible to provide a mobile communication system that can reduce the power consumption and size of a mobile wireless terminal and reduce traffic on a wireless channel. The present specification is based on Japanese Patent Application No. 11-312-153 filed on Jan. 2, 1999. This content is included here. Industrial applicability

INDUSTRIAL APPLICABILITY The present invention is suitable for use in a mobile communication system that handles mobile wireless terminals such as a mobile phone and a PHS terminal, and in particular, is used in the field of mobile communication systems having a function of detecting the position of a mobile wireless terminal.

Claims

The scope of the claims

1. By receiving a signal transmitted by the base station apparatus to be communicated and instructing calculation of position information, a timing signal transmitted by a reference base station apparatus in a plurality of base station apparatuses including the base station apparatus A mobile radio terminal device for calculating an arrival time difference between the base station device and the timing signal transmitted by each base station device other than the reference base station device, and transmitting the calculated arrival time difference to the base station device to be communicated with; Mobile communication system.

2. The mobile wireless terminal device according to claim 1, wherein the calculated arrival time difference is transmitted to the communication target base station device according to a moving state when a signal instructing calculation of position information is received. Mobile communication system.

3. The mobile communication system according to claim 2, wherein the mobile radio terminal device detects a moving state based on a change in a reception level of a signal transmitted by the base station device.

4. The mobile communication system according to claim 2, wherein the mobile wireless terminal device detects a moving state based on a change in the calculated arrival time difference.

5. The mobile communication system according to claim 1, wherein the mobile radio terminal device transmits a signal for instructing calculation of position information by a base station device to be communicated according to a moving state of the mobile radio terminal device. .

6. The mobile communication system according to claim 5, wherein the communication target base station device detects a moving state of the mobile radio terminal device based on a reception level of a signal transmitted by the mobile radio terminal device.

7. The mobile communication system according to claim 5, wherein the communication target base station device detects a moving state of the mobile wireless terminal device based on a propagation delay of a signal transmitted by the mobile wireless terminal device.

8. The mobile communication system according to claim 1, wherein the mobile wireless terminal device maintains a communication state or a standby state relationship with a base station apparatus to be communicated with.

9. Using the time difference of arrival received via the base station The mobile communication system 1 according to claim 1, further comprising a position calculation station that calculates a position of the terminal device.