JPH04185026A - Mobile communication system and mobile machine - Google Patents

Abstract

PURPOSE:To efficiently use communication channels by practically reducing a radio zone of high use rate and securing an idle channel for a new call in this zone in the mobile communication system where a mobile machine measures the field intensity of the control channel of a base station to find a base station at the movement destination. CONSTITUTION:A hand-over switching reference level transmitting means 15 in a control station 11 monitors the use rates, namely, the traffic of communication channels in reference stations 131 to 13n in a control zone and discriminates the hand-over switching reference level in each of new radio zones 121 to 12n based on this monitor information and transmits the hand-over switching reference level higher than the present value to the reference station in the radio zone where the use rate of communication channels is higher. Thus, hand-over is requested to a mobile machine placed in the periphery of the radio zone, where the use rate of communication channels is high, out of plural radio machines placed in this radio zone through its hand-over means, and an idle channel is secured even in the zone of high use rate.

Description

[Detailed Description of the Invention] [Summary] An object of the present invention is to effectively allocate wireless communication channels in a mobile communication system and a mobile device in which the mobile device measures the electric field strength of the control channel of the base station and learns the base station to which it is moving. A base station is placed in each of a plurality of wireless zones, the plurality of wireless zones are controlled by a control station as one control zone, and call requests from mobile devices are received within the wireless zone in which the mobile device is located. In a mobile communication system in which the control station notified by a base station specifies a communication channel to be used for the base station, the control station monitors the usage rate of the communication channel for each of the plurality of wireless zones. , a handover switching reference level transmitting means for setting a handover switching reference level value according to the usage rate and transmitting it to a plurality of mobile terminals through the plurality of base stations, the plurality of mobile terminals receiving a comparison means for comparing the handover switching reference level and the current received field strength, and when a comparison result is obtained that is smaller than the handover switching reference level, A handover that measures the control channel received field strength from a base station within the wireless zone and, based on the measurement results, sends a handover request to a predetermined base station to the base station within the wireless zone that is currently located. requesting means.

[Industrial application field]

The present invention relates to a mobile communication system and a mobile device, and more particularly to a mobile communication system and a mobile device in which the mobile device measures the electric field strength of a control channel of a base station to know the base station to which the mobile device is moving.

A mobile communication system having a zone configuration consisting of, for example, seven repeating radio zones, as shown in FIG. 5, is known from the point of view of effective frequency utilization. In the figure, a base station (BS) exists at the center of each wireless zone indicated by 1 to 7, and different frequencies are used, and the same frequency is used in zones with the same number. In addition, the control zone is 7
The channel configuration consists of a control channel (C-CH) and a communication channel (v-CH), which are the downlink from the base station (BS) to the mobile station (MS), (MS) to the base station (BS) (uplink).

Further, C-CH and V-CH are assigned to each wireless zone. In addition, the base station (BS) in each wireless zone
) and a mobile station (MS) is performed using a time division multiple access (TDMA) method, and a nm mobile station communicates with a base station using one time slot.

In such a mobile communication system, it is important to effectively allocate communication channels within the wireless zone where the mobile device is located.

[Conventional technology]

In conventional mobile communication systems, handover for wireless communication channel allocation is performed as follows. First, when a base station enters a call, it notifies the mobile device in communication of the control channels of base stations surrounding the currently located base station using control data within the used time slot.

The mobile device measures the received field strength of the channel currently communicating with the base station, and when the measurement result is below the reference level, it uses an empty time slot other than the one currently used for communication, and Measure the received field strength of the control channel of the base station. Based on changes in this measurement result, the mobile device can know which wireless zone it is moving toward (it can also know the base station to which it is moving).

Subsequently, the mobile device transmits a handover request to the base station with which it is currently communicating. Thereby, the base station notifies the control station of the above handover request. Based on the request, the control station checks the available communication channel and time slot of the destination base station, and if there is an available communication channel and time slot of the destination wireless zone to the base station that made the handover request. Along with notifying the slot,
The mobile device notifies the destination base station that it will hunt over.

Thereafter, the mobile device receives the communication channel and time slot data of the destination wireless zone from the base station with which it is currently communicating, and based on this, the mobile device switches to the received communication channel, thereby completing handover.

[Problem to be solved by the invention]

Nowadays, the number of subscribers to mobile communication systems is increasing and wireless zones are becoming microcells. Particularly in urban areas, the usage rate of mobile devices temporarily increases in certain wireless zones, and the surrounding areas A case may occur in which a free communication channel exists in a wireless zone.

In such a case, in the conventional mobile communication system described above, the mobile device is configured to not output a handover request unless the electric field strength of the channel currently communicating with the base station falls below the reference level. New calls made and received by mobile devices located in the zone are ignored because there are no available channels, resulting in a situation where no service is available.

The present invention has been made in view of the above points, and an object of the present invention is to provide a mobile communication system and a mobile device that can effectively allocate wireless communication channels.

[Means to solve the problem]

FIG. 1 shows a basic configuration diagram of a mobile communication system according to the present invention. As shown in the figure, the present invention provides a plurality of wireless zones 1
2t~12. Every base station 13+~! 3. The plurality of wireless zones 121-12 are controlled as one control zone by the control station 11, and call requests from mobile devices 1411-14□ are handled by mobile device 141. ~143. In a mobile communication system in which a control station 11 notified from a base station in a wireless zone in which it is located specifies a communication channel to be used for that base station, a handover switching reference level transmitting means 15 is provided in the control station 11. , and mobile devices 1411~
Each of 14□ includes a comparison means 161 for comparing the received handover switching reference level and the current received electric field strength.
1-161. and handover requesting means 17II-1.
7°.

Here, the handover switching reference level transmitting means 15 transmits information to a plurality of wireless zones 12 . The usage rate of the communication channel is monitored for each of the mobile stations 141 . . . . . . . . . . . . . ~14. ．． Send to.

Furthermore, handover request means 17nm to I7. .

are the comparison means 1611-161. When a comparison result is obtained in which the received electric field strength is smaller than the received handover switching reference level, the received electric field strength of the control channel transmitted from the base station in the wireless zone surrounding the wireless zone in which you are currently located is Based on the measurement results, a handover request to a predetermined base station is transmitted to the base station in the wireless zone where the base station is currently located.

Furthermore, the mobile device according to the present invention includes a plurality of base stations 13, .
3. In the case where information from the handover switching reference level transmitting means 15 is added to the control channel broadcast information and transmitted, the control channel information is received during standby, and the handover switching reference level in the received information is transmitted. a comparison means for comparing the received field strength of the control channel with the received field strength of the control channel from each base station when the received field strength of the control channel is smaller than the reception handover switching reference level; and scanning means for performing a scan during standby to find a control channel with the second highest received field strength.

[Effect]

In the mobile communication system according to the present invention, the handover switching reference level transmitting means 15 within the control station 11 or the base station 13 within the control zone. ~13. The usage rate (traffic) of the communication channel is monitored, and based on that information, new wireless zones 12+ to 12. The handover switching reference level is determined each time, and a handover switching reference level higher than the current value is transmitted to the base station in the wireless zone where the communication channel usage rate is high. As a result, among multiple mobile devices located in a wireless zone with a high communication channel usage rate, a handover is sent to a mobile device located in the periphery of that wireless zone via the handover request means. You can ask for overs. Therefore, in the present invention, the size of a radio zone with a high usage rate can be substantially reduced, so that it is possible to secure an empty communication channel for a new call within a radio zone with a high usage rate. can.

Furthermore, in the mobile device according to the present invention, among mobile devices located in a radio zone with a high usage rate, a mobile device in standby located near the zone receives communication channels by scanning means. When the mobile device finds the control channel with the second highest received field strength and makes a new call, the mobile device issues a call request to the base station of the found control channel. A call request can be made to a base station in an adjacent wireless zone that has an empty communication channel, rather than to a base station in a wireless zone with a high usage rate.

〔Example〕

FIG. 2 shows a system configuration diagram of an embodiment of the present invention. In the figure, the same components as in FIG. 1 are denoted by the same reference numerals, and their explanations will be omitted. In Fig. 2, the control station (hereinafter referred to as C8
) 11 are three base stations (hereinafter referred to as BS) 13
+, 13. and controls 13 units. BS 13+, 1
3 and 13. are 12+, 12* and 12. respectively. is defined as a wireless zone, and wireless communication is performed with a mobile device (hereinafter referred to as MS) using a control channel and a communication channel at mutually different frequencies. However, the wireless zone is 121°12!
, 12s, wireless communication is performed in the same wireless zone using a single frequency using the TDMA method.

Now, as shown in Figure 2, within the wireless zone 12+, there are
11 mobile stations (MS) 141. ~141□ is in the area,
Among them, MS 14 ++ ~ 1411° is B513. It is assumed that the MS 141□ is in communication with the MS 141□ and is on standby. Also, wireless zone 12. Inside is MS 14*+,
141$+14+s and 1417 are in the area, of which MS14! + is communicating with B513, and wireless zone 12. MS14□, 14nm. 14111
4116 are in the area, of which MS142. is B S 1
3 It is assumed that communication is in progress with s.

Furthermore, wireless zone 12. All B5131 communication channels are used within the MS t 4nm to 14nm. and B
While wireless communication is being carried out with the adjacent wireless zone 12. In 12s and 12s, the number of MSs in communication is small, and each B5132.133 has a large number of empty communication channels.

Next, the operation of each part in the mobile communication system in this state will be explained with reference to FIG. 3.

If there is a call request from an MS, the C3lI receives the request from the BS in the wireless zone where the MS is located, and transmits the request to the BS.
Checks whether there is a free communication channel in the BS, and if so, specifies the communication channel to be used to the BS.

On the other hand, when a call is received from the switching network to an MS within the control area, the C3I searches for the wireless zone in which the MS is located based on the location registration data, and checks whether the corresponding BS has a free communication channel. And if there is, its BS
Allocate communication channels to

As mentioned above, C3lI corresponds to each B513. ~13, are managing communication channels.

Therefore, C3lI monitors this communication channel and BSt3. If the usage rate of the communication channel exceeds a predetermined value,
and BS 132 and 13. It can be seen that the usage rate of the communication channel is less than a predetermined value.

This allows C3lI to pass through B513+ to B513.
A new handover switching reference level (hereinafter also referred to as "handover level") with a higher value than the current value is sent to the MS 14 + to I4110 that is communicating with the MS 14+ to I4110 (steps 101 and 102 in FIG. 3). .At this time, C3lI is B513□.

Although it is not necessary to send the handover switching reference level for 13s, it is also possible to send a new handover switching reference level with a lower value than the current value (
Step 103 in FIG. 3).

The wireless zone 121 has a dashed line 12 in FIG. 2 due to its huntover switching reference level being changed to a higher value.
As shown by +', the zone area becomes substantially narrower. This causes MS 141 . ~
141. . Among them, if you are located in wireless zone 12, or wireless zone 12. MS 14 +s to 14□ located in the periphery of wireless zone 12+ such that they are no longer located in '.

is the received new handover switching reference level and B5.
Comparing the received field strength of the 13+ communication channel (
At step 104 in FIG. 3), a comparison result (weak determination) in which the received electric field strength is lower is obtained (step 105 in FIG. 3), so MS14+s~141□. In order to confirm his/her destination, he uses an empty time slot and calls B5132 and 1 in the adjacent wireless zones 122 and 12s.
3. The received electric field strength of the control channel from the control channel is measured (step 106 in FIG. 3).

As a result of the above measurement, MS14+s~1417 is B513
It is known that the received electric field strength of the control channel is the highest for MS14nm~141. . know that the received field strength of the control channel of base station 131 . Sends a handover request to IL to the currently communicating BS 13+ (step 107 in Figure 3).
．． 108).

C3lI is MS t 4n through B S l 3 +
When a handover request is received from m~1411° (
Step 109 in Figure 3), MS 1415-14
B513 for 1°. The communication channel of BS 132 is specified through MS 14nm to 141.

The communication channel of BS 132 is specified through BS 131 (steps 110 and 11 in FIG. 3).
1). Also, C3lI is the destination BSI L.

13, against MS14+s~14. i, MS14. .

~14,1° notifies that handover is coming (step 112 in FIG. 3). As a result, B513□
, 13. is MS 140~1417+MS14□
~1411° is sent out waiting for loop confirmation (
Step 113 in FIG. 3).

MS14+s~1417, 14+s~14110 sends a channel designation data reception response to C3ll through B5131.
After this (third step 114, 115), channel switching is performed to the specified new communication channel of B513*, 13s (step 116 in FIG. 3). After that, MS14+s~14,7 returns a loop confirmation with B5132, and MS143. ~148. . is B
B5131.1 Loop confirmation return with SIL
3. to C3lI (step 11 in Figure 3).
7.118), B513a, 1, 3s continue wireless communication (step 119 in FIG. 3). On the other hand, C3lI
Upon receiving the above loop confirmation return, B513. (Step 120 in FIG. 3)
).

As a result, six free communication channels are generated for B5131, which was previously unable to communicate because there were no free communication channels. MS141 located near
1 can communicate via BS131.

As shown in steps 101 and 103 in FIG. 3, all B5131-13. A better system can be constructed if the handover nm switching reference level is transmitted to the user, and the level is varied and specified in accordance with the usage rate.

In addition, in the above embodiment, the handover switching reference level is notified to the communicating MS through the communication channel, and the communication channel is intended to be effectively used in the wireless zone 121, which has a high usage rate. The invention is not limited to this,
According to the instructions from C5II, handover switching reference level information of the communication channel of the wireless zone is added to the control channel information of BS+3+ to BS+13s, and the M
It is also possible to notify S.

Next, the operation of the mobile device in such a mobile communication system will be explained with reference to the flowchart of FIG. First, among mobile devices in standby, a mobile device that wants to start a new communication scans the control channels assigned throughout the system in order to know the wireless zone in which it is located, and after scanning, the field strength is adjusted. The control channel is fixed to the highest control channel (step 201). Next, it is checked whether the handover switching reference level is received in the received information of the control channel (step 202). If received, it is checked whether the value is greater than the current received field strength of the control channel (step 203).

Among mobile devices located in a wireless zone with a high communication channel usage rate, mobile devices located on the periphery of that wireless zone may have received field strength that falls below the node over switching reference level. In this case, the received field strength of the control channel from each base station including the wireless zone adjacent to the wireless zone is measured, and the control channel with the second highest received field strength is fixed (step 204).
. As a result, the mobile device changes and fixes the control channel from the control channel with the highest received field strength to the second highest control channel.

Thereafter, the mobile device receives broadcast data of the newly fixed control channel, makes a call request therefrom, and receives communication service (step 205).

According to the mobile station having such a configuration, if, for example, the mobile station (MS) 14zo in FIG. 2 makes a new call, the mobile station (MS) 14z will make a new call. During its standby, it fixes to the control channel from the BS 13s with the second highest received field strength and issues a call request to the BS 13s.

In this way, according to the present embodiment, the mobile phone 14□ is located in the wireless zone 121 with high traffic. Mobile devices can use communication channels more efficiently.

〔Effect of the invention〕

As described above, according to the mobile communication system of the present invention, by substantially reducing the wireless zone with high usage rate,
Since an empty communication channel can be secured for a new call within the wireless zone, communication channels can be allocated effectively. If you are located in the area, you can fix the control channel during standby and issue a call request to the base station in the wireless zone that has an adjacent free communication channel, so you can efficiently use the communication channel. It has features such as being able to communicate using a vacant communication channel.

[Brief explanation of the drawing]

FIG. 1 is a diagram of the principle configuration of the present invention, FIG. 2 is a system configuration diagram of an embodiment of the present invention, FIG. 3 is a sequence explanatory diagram of an embodiment of the present invention, and FIG. 4 is a mobile device of the present invention. Flowchart for explaining the operation of one embodiment. FIG. 5 is a diagram for explaining the zone configuration. In the figure, 11...control station (C8), 12, ~12. ...wireless zone, 13, ~13. ...Base station (BS), 1411-14
nm--Mobile station (MS), 15... Handover switching reference level transmitting means, 16.1-161. . . . comparison means, 17.1 to 17°, . . . indicates handover requesting means. System summary of an embodiment of the present invention Fig. 2 Flowchart for explaining the operation of an embodiment of the mobile device of the present invention Fig. 4 Diagram illustrating zone configuration Fig. 5

Claims (4)

[Claims] (1) A base station (13_1 to 13_n) is arranged in each of a plurality of wireless zones (12_1 to 12_n), and the plurality of wireless zones (12_1 to 12_n) are controlled by a control station (11) as one control zone, Mobile device (14_1_1~
14_n_m) from the mobile device (14_1_m).
In a mobile communication system, the control station (11) receives notification from a base station in a wireless zone in which the base station (1 to 14_n_m) is located and specifies a communication channel to be used for the base station. Multiple wireless zones (12_
The communication channel usage rate is monitored for each of the base stations (1 to 12_n), a handover switching reference level value is set according to the usage rate, and it is applied to each of the plurality of base stations (13_1 to 13_n).
_n) through multiple mobile devices (14_1_1 to 14_n
_m), the plurality of mobile devices (14_1_1 to 14_n_m) have comparison means for comparing the received handover switching reference level with the current received electric field strength. (16_1_1~16_n
_m) and the comparison means (16_1_1 to 16_n_m)
When a comparison result is obtained in which the received field strength is smaller than the received handover switching reference level, the received field strength of the control channel in the wireless zone around the currently located wireless zone is measured, and the received field strength is measured. A mobile communication system characterized by having handover request means (17_1_1 to 17_n_m) that transmits a handover request to a predetermined base station to a base station in a currently located wireless zone based on a measurement result. . (2) The plurality of base stations (13_1 to 13_n) add the information from the handover switching reference level transmitting means (15) to the communication channel information and transmit it to the mobile device currently communicating, The comparison means (16_1_1-1
The handover request means (17_1_1 to 17_n) compares the received handover switching reference level with the received field strength currently in communication,
_m) measures the received field strength from base stations surrounding the currently communicating base station, and sends a handover request to the base station with the highest received field strength to the currently communicating base station. The mobile communication system according to claim 1, characterized in that: (3) The plurality of base stations (13_1 to 13_n) add information from the handover switching reference level transmitting means (15) to broadcast information on a control channel and transmit the resultant information. mobile communication system. (4) A mobile device operating within the mobile communication system according to claim 3, which receives control channel information during standby, and includes the handover switching reference level in the received information and the received electric field of the control channel. Comparison means (202, 203) for comparing the strength and the comparison means (202, 203)
When a comparison result is obtained in which the received field strength is smaller than the received handover switching reference level, the received field strength of the control channel from each base station in the wireless zone in which it is located and the surrounding wireless zones is determined. scanning means (204) for performing scanning during standby to find the control channel with the second highest received field strength;
A mobile device comprising: