JPH02171039A - Speech channel changeover device - Google Patents

Abstract

PURPOSE:To decease a channel interruption time considerably at channel changeover during speech and to attain sure changeover of a speech channel by providing a position detection means detecting a position of a mobile equipment. CONSTITUTION:An antenna 32 for global positioning system(GPS) and a GPS receiver 26 receive a radio wave from plural artificial satellites and calculate the present position of an automobile, that is, a mobile equipment. Moreover, an earth magnetism sensor 28 detects the earth magnetism to find out the advancing direction of the mobile equipment. When the GPS detects the position of the mobile equipment, it is compared with the position of a radio zone in a zone map ROM 30. As a result, whether or not the position of the mobile equipment is at a border of the radio zone is recognized, and the radio zone selection CPU 24 sends a zone revision signal designating the radio zone to be advanced next in response to the position of the mobile equipment specified by the GPS. Thus, the channel changeover at the speech channel changeover is quickened to attain sure changeover of the speech channel.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a communication channel switching device that switches communication channels when a wireless zone changes in mobile communication such as a car phone.

[Background Art] With the recent progress in communication technology, mobile communications such as car phones are becoming widespread. In this mobile communication, a transmitter/receiver is mounted on a moving car or the like, and wireless communication is performed with an i-wireless base station. Since the radio base station is connected to a normal telephone line via a radio network control station and a mobile telephone exchange, it is possible to make calls using a mobile telephone or the like.

Here, each radio base station defines its own radio zone as a range in which it can sufficiently communicate with mobile stations, and by providing a large number of radio base stations, radio communication is possible in a predetermined area. That is, by setting a predetermined area as a wireless zone of one of the plurality of wireless base stations, wireless communication in that area is enabled.

In this way, a mobile device such as a telephone installed in a car performs wireless communication with a corresponding wireless base station at that location. Therefore, when a mobile device moves from one wireless zone to another during a call while traveling, it is necessary to change the wireless base station. The wireless base station allocates one of its own channels to the mobile station for communication, and since the channel is different between adjacent wireless zones, when the wireless zone is changed. In order to do this, it is necessary to perform a one-time channel changeover to an empty channel among communication channels used with the wireless base station in the destination wireless zone.

However, there are no clear boundaries between wireless zones, and the strength of radio waves gradually decreases as the area approaches the periphery. Near the boundaries of each wireless zone, the radio waves of both wireless base stations overlap while fluctuating. Therefore, in channel switching during a call, the zone with the highest reception level is selected from a plurality of wireless zones and connected due to such fluctuation characteristics.

Next, the control operation for switching channels during a call will be explained based on FIG. 5. In the figure, wireless base station 10A
, 10B, IOC is wireless zone 100A, 100B, 1
Located at the center of each of 00C. The wireless base station 10 includes a wireless network control station 12, a mobile telephone exchange 1
4. Connected to subscriber line switching center 18 via trunk line switching center 16. As a result, mobile device X and telephone device Y
It is possible to make calls.

Here, a case will be described in which mobile device X, which was talking in wireless zone 100A, moves toward wireless zone B.

(a) In this case, the wireless base station 10A that has jurisdiction over the wireless zone 100A constantly monitors the reception level of the communication channel from mobile device X, and the reception level is the specified value (15 dB
μ), it is known that mobile station X is moving out of its own zone (wireless zone 100A).

(b) The radio base station 10A notifies the radio network control station 12 of the deterioration of the reception level in the communication channel.

(c) The radio network control station 12 that received the notification
The base station 10 in the wireless zone 100 in and around 00A is instructed to monitor the communication channel reception level.

Here, each base station 10 has, in addition to control and communication receivers, an S/N monitoring receiver that monitors the reception level for channel switching during a call. And this S/
The reception level can be monitored by switching the channel of the N monitoring receiver to the communication channel instructed by the radio network control station 12.

(d) Each radio base station 10 switches the receiving channel of the S/N monitoring receiver based on the command, measures the reception level of the radio wave from mobile device X, and reports the result to the radio network control station 12. .

(e) The radio network control station 12 that receives the reception level report from each radio base station 10 determines that the radio zone 100 with the highest reception level is the zone to which the mobile device X will move.

(f) The mobile telephone exchange 14 conducts a wired continuity test with the wireless base station 10B regarding the new communication channel.

(g) If the test is successful, the communication channel of the original wireless base station 10A (mobile device X is still in wireless zone 1 at this point)
00A), sends out a busy channel change signal to switch to a new conversation channel.

(h) Mobile device X follows this instruction to create a new wireless zone B.
Switch to the call channel.

(i) The wireless base station 1OB in the new wireless zone 100B conducts a wireless continuity test with the mobile device X regarding the new communication channel.

(j) If the continuity test is good, the car 7u telephone exchange 1
4 switches the communication path from the old channel in the wireless zone 100A to the new channel in the wireless zone 100B to continue the conversation.

[Problems to be Solved by the Invention] Channel switching during a call in a conventional car phone was performed as described above. For this reason, there were the following problems.

(a) Since it is determined that mobile device It is impossible to distinguish between cases where the reception level is reduced due to radio wave shielding effects caused by the width of the road, the direction of the road and radio waves, and the undulation of the terrain, and cases where the reception level is reduced due to movement to the boundary area. be.

(b) In order to solve this problem, in the past, a radio continuity test was carried out between the radio base station and mobile device Excluded. However, in order to conduct such a wireless continuity test, a distance of several hundred meters is required.
It takes 5. For this reason, adding several tens of Ils when switching the communication channel at the mobile device occurs, and call quality deteriorates.

On the other hand, it has also been proposed that a wireless control station constantly grasp the movement trajectory of a mobile device, estimate the course of the mobile device based on the trajectory information, and switch communication channels. For example, Japanese Patent Laid-Open No. 60-90441 discloses the following system.

That is, the wireless base station issues an instruction to transmit a distance measurement packet, and the mobile device that receives the instruction sends a response packet back to the wireless base station at a predetermined timing. Then, the radio base station determines the distance to the mobile device based on this response time, and sends this to the radio control station. The radio control station stores the distances between the mobile device and the radio base station, learns the trajectory of the mobile device, and switches the communication channel appropriately.

However, such communication channel switching devices have the following problems.

(a) Since each wireless base station requires a distance measurement channel, the number of communication channels per wireless zone decreases.

(b) When transmitting and receiving packets, it is necessary to switch channels, measure distances, etc., which increases the burden on the wireless base station.

(c) The call is momentarily disconnected when transmitting and receiving packets for distance measurement.

(d) The radio network control station must monitor the trajectories of all mobile devices during a call, and the processing processor becomes very large. In other words, for example, there are 3 wireless base stations (wireless zones) per wireless network control station in a large city.
2, and the number of communication channels per wireless zone is 12.
There are approximately 0 channels. Therefore, the number of mobile stations per radio network control station is approximately 3,840, and storing all of these trajectories requires a considerably large storage capacity.

(e) Control when switching communication channels becomes complicated;
It is not suitable for a small zone (cell) system that aims to improve the efficiency of radio frequency use by making the wireless zone smaller.

The present invention has been made with the aim of solving the above-mentioned problems, and provides a communication channel switching device which has a very short communication path disconnection time when switching channels during a communication, and which can reliably switch communication channels. The purpose is to provide.

[Means for Solving the Problems] In order to achieve the above object, the speech channel switching device according to the present invention includes: a position detecting means for detecting the position of a mobile device; and a moving direction detecting means for detecting the moving direction of the mobile device. means, a zone map storage means for storing the positions of radio zones to be controlled by each of the plurality of radio base stations, and recognition that the mobile device has reached a boundary area adjacent to a radio zone to be controlled by another radio base station; an entry zone determining means for determining a wireless zone to enter next according to the detection result of the moving direction detecting means and the stored content of the zone map storage means when reaching the boundary area; and a wireless base. and zone change signal transmitting means for transmitting to the station a zone change signal specifying the next wireless zone to enter, and is characterized in that the mobile device specifies and specifies the wireless zone.

[Operation] The communication channel switching device according to the present invention has the above-described configuration, and performs communication channel switching in the following manner.

That is, by detecting the position of the mobile station by the position detection means and comparing it with the position of the wireless zone stored in the zone map storage means, it is recognized whether the position of the mobile station is in the boundary area of the wireless zone. do. and,
When the mobile station reaches the boundary area, it refers to the detection result of the moving direction detecting means and determines which wireless zone it will enter next.

Then, the mobile station transmits to the radio base station a zone change signal specifying the next radio zone to enter. Therefore, the radio base station switches channels in response to a command from the mobile station.

[Embodiment] Hereinafter, an embodiment of the communication channel switching device according to the present invention will be described based on the drawings.

FIG. 1 is a block diagram showing the configuration of a communication channel switching device according to the present invention, in which an antenna 20 for an automobile Mini 3 is shown.
is attached to a car and is used for heavy-duty transmission and reception in cars 1a2
The radio waves sent from the radio base station are transmitted to the car phone transceiver 22.
supply to.

The car telephone transceiver 22 transmits and receives these transmitted and received signals to and from the main body of the m-active device (not shown), thereby making it possible to make a telephone call. Here, the car phone transceiver 22 has a plurality of channels, and uses radio waves of a frequency corresponding to the selected channel as a carrier for communication via the car phone antenna 20.

This channel selection is performed by the wireless zone selection CPU 24. Then, this wireless zone selection CPU 24
is equipped with a GPS receiver 26 for locating the vehicle.
, data from a geomagnetic sensor 28 that measures the traveling direction of the vehicle is supplied. Furthermore, a zone map ROM 30 that stores the positions of wireless zones under the jurisdiction of a plurality of wireless base stations is connected to the wireless zone selection CPU 24.
24 can read out the stored contents of the zone map ROM 30 as appropriate. Note that the GPS antenna 32 receives signals from satellites and supplies them to the GPS receiver 26.

Here, the GPS antenna 32 and the GPS receiver 26 are connected to the Global Positioning System (Global Positioning System).
nIng System (hereinafter referred to as GPS), receives radio waves from multiple artificial satellites and calculates the current position of the vehicle. On the other hand, the geomagnetic sensor 28 detects the geomagnetism and detects the direction in which the vehicle is traveling.

Next, channel switching control during a call in the wireless zone selection CPU 24 will be explained based on FIG. 2.

When making a telephone call, lift the receiver (off-hook)
is started by. Therefore, off-hook is detected first (Sl). When off-hook, position measurement is performed using a GPS comprising a GPS antenna 32 and a GPS receiver 26 (S2).

As a result, the current position (latitude and longitude) of the automobile, that is, the mobile device X is detected. When this position detection is performed, a wireless zone is selected according to the detection result. Regarding the above-mentioned GPS, for example, Japanese Patent Laid-Open No. 61-19
The one shown in No. 6180 can be adopted.

In the apparatus of this embodiment, maps for wireless zones 100 in a plurality of wireless base stations 10 are stored in a zone map ROM 30.

That is, the zone map ROM 30 stores positional information about the wireless zone 100 of each base station 10 as shown in FIG. 3 in terms of its latitude and longitude.

Therefore, the zone selection CPU 24 can select which wireless zone 100 the vehicle belongs to according to the position of the vehicle specified by GPS (S3). In FIG. 3, since mobile station X initially belongs to wireless zone 100A, this wireless zone 100A is selected.

Here, each wireless zone 100 is defined as a range within which radio from the wireless base station 10 can sufficiently reach, and thus becomes a circular area centered on the wireless base station 10, as shown in FIG.

Therefore, adjacent wireless zones 100 overlap. The overlap region R indicated by diagonal lines in the figure is defined as a boundary region. When a car enters this overlap area R, it often moves to another wireless zone 100, so it is determined whether or not there is a vehicle in the overlap area R of the wireless zone 100 (S4). In the figure, wireless zone 100A
Mobile device X is entering the overlap area R between 100B and 100B.

In addition, in order to make these judgments, zone map ROM3
0, in addition to the position of the wireless base station 10 which is the center point of each wireless zone 100, the radius of the wireless zone 100, etc.
It stores position information about a regular hexagonal wireless zone 100 that divides an overlap region R shown by a broken line in FIG. 3 by a center line. Then, 100 wireless zones were selected (S
3) is performed using the regular hexagonal wireless zone 100, and whether or not the area is within the overlap portion R is determined based on the circular area (S4).

If the vehicle position is not within the overlap area R, the mobile device
A wireless zone registration signal is transmitted to the wireless base station 10 using the control channel in (S5).

That is, when located in the wireless zone 100A, the signal is transmitted to the wireless base station 10A.

The radio base station 10A that has received this registration signal detects an empty channel that is not currently being used in the radio zone 100A where the mobile device X exists, and sends a channel designation signal to the mobile device Send to. Therefore, on the mobile device X side, the wireless zone registration signal transmission (S5) is repeated until the channel designation signal is received.

If the channel designation signal is received, the communication channel in the mobile device X is set to the designated channel (S7), and the channel selection operation is ended. Therefore, the channel selected here is adopted as the channel directed to the automatic four-power transmitter/receiver 22, and telephone communication is performed in this state.

Note that since it is only necessary to transmit the wireless zone registration signal (S5) for the first time, it is preferable to return to the position measurement (S2) from the second time onwards unless the area is in the overlap area R.

Next, when the vehicle is located within the overlap portion R of the wireless zones 100A and 100B during driving, the direction of travel of the vehicle is then measured based on the signal from the geomagnetic sensor 28 (S8). Then, the wireless zone 100B is selected as the next transition destination zone in accordance with the detected traveling direction (S9). When the destination zone is set in this way, the mobile device X transmits a wireless zone change signal to the wireless base station 10A (S10). This wireless zone change signal is transmitted before the mobile device X crosses the boundary line of the wireless zone 100. This wireless zone change signal is transmitted in the communication channel to the wireless base station 10A using the lower band (0 to 300 Hz) outside the voice band (0, 3 to 3 kHz) as shown in FIG. It is transmitted simultaneously on the same carrier as the call signal.

The radio base station 10A transmits the signal for the radio zone 100B specified in this radio zone change signal to the radio network control station 12, and the radio network control station 12 provides an empty channel to the migration destination radio base station 10B. Let it be detected. Information about this vacant channel is then transmitted from the original radio base station 10A to the mobile device X as a signal within the communication channel similar to the radio zone change signal, that is, a channel designation signal. When mobile station X receives this channel designation signal (Sll), it switches to the communication channel designated by this signal (S7). by this,
The communication channel switching is completed and the new wireless base station 10B
The call will continue between the two.

As described above, in this embodiment, the exchange of control signals other than phone calls between the mobile device I will do it. Therefore, there is no call interruption when transmitting and receiving control signals, and control signals can be communicated at the same time.

Note that in the above-described embodiment, GPS was used as the position detection means for the mobile device X. The present invention is not limited to this, but the position is detected according to position information from a sign post installed on the road side that transmits position information, and then continuously by inertial navigation using a geomagnetic sensor and a vehicle running sensor. The position of the mobile device X may also be detected. In addition, in the above embodiment, the wireless zone to which to migrate was selected based only on the detection value of the geomagnetic sensor. It is also possible to select more accurately.

[Effects of the Invention] As explained above, according to the communication channel switching device according to the present invention, the mobile device X side detects its own position and direction of travel, and the mobile device Specify a wireless zone. Therefore, it is possible to prevent the communication channel switching operation from being erroneously delayed due to locational factors, and it is also possible to perform the switching operation quickly. Furthermore, since there is no need to constantly monitor the radio level at the radio base station, and the best radio base station can be selected at the mobile device, there is no need for a radio continuity test.

Furthermore, since the load on the radio base station and radio network control station side can be reduced, it can be effectively applied to a small zone system.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of a speech channel switching device according to the present invention, FIG. 2 is a flow chart diagram for explaining the operation of the wireless zone selection CPU 24 in the same embodiment, and FIG. FIG. 4 is an explanatory diagram showing the relationship between the wireless base station 10 and the wireless zone 100, FIG. 4 is a characteristic diagram showing frequency spectra of control signals and voice signals, and FIG. 5 is a configuration diagram showing the configuration of a conventional mobile communication system. 10... Wireless base station 20... Car phone antenna 22... Car phone transceiver 24... Wireless zone selection CPU 26...
GPS receiver 28 ... GPS antenna 30 ... ROM for zone map

Claims (1)

[Claims] (1) A position detecting means for detecting the position of a mobile device, a moving direction detecting means for detecting the direction of movement of the mobile device, and a zone map storage means for storing the positions of wireless zones to be controlled by each of a plurality of wireless base stations. and boundary area recognition means for recognizing that the mobile device has reached a boundary area adjacent to a wireless zone to be controlled by another wireless base station; An entry zone determining means for determining the next wireless zone to enter according to the stored content of the zone map storage means; and a zone change signal for transmitting a zone change signal specifying the next wireless zone to enter to the wireless base station. A communication channel switching device comprising: a transmitting means; and specifying a wireless zone in a mobile device.