JP2826189B2 - Mobile communication system and mobile device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] The present invention relates to a mobile communication system and a mobile station in which a mobile station measures the electric field strength of a control channel of a base station to know a destination base station, and to effectively allocate a radio communication channel. A base station is arranged for each of a plurality of wireless zones, and the plurality of wireless zones are controlled by a control station as one control zone,
In a mobile communication system in which the control station notified of a call request from a mobile station from a base station in a wireless zone where the mobile station is located specifies a communication channel to be used for the base station, The station monitors a usage rate of a communication channel for each of the plurality of wireless zones, sets a handover switching reference level value according to the usage rate, and transmits the reference value to a plurality of mobile stations through the plurality of base stations. Comparing means for comparing the received handover switching reference level with the current received electric field strength, wherein the plurality of mobile units are smaller than the handover switching reference level. When the comparison result is obtained, the control channel reception electric field strength from the base station in the wireless zone around the currently located wireless zone is measured, and based on the measurement result, Te configured to have a handover request means for transmitting to a base station in a radio zone currently serving a handover request to a given base station.

[Industrial applications]

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 a destination base station.

As shown in FIG. 5, the mobile communication system has, for example, a zone configuration including seven repetitions of wireless zones.
It is known from the point of effective use of frequency. In FIG.
A base station (BS) exists at the center of each wireless zone indicated by, and different frequencies are used, and the same frequency is used in zones of the same number. The control zone is 7
There are two radio zones, and the channel configuration includes a control channel (C-CH) and a communication channel (V-CH), and a line (downlink) from the base station (BS) to the mobile station (MS) and a mobile station, respectively. It is divided into a line (uplink) from the (MS) to the base station (BS). Also, C-CH and V-CH are allocated to each wireless zone. In addition, wireless communication between the base station (BS) and the mobile station (MS) in each wireless zone is performed by a time division multiple access (TDMA) system, and one mobile station has one time in terms of the base station. Communication is performed using slots.

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

[Conventional technology]

In a conventional mobile communication system, handover for allocating a wireless communication channel is performed as follows. First, the base station notifies the communicating mobile station of the control channel of the base station in the vicinity of the currently located base station by using control data in the used time slot when entering a call. The mobile station measures the received electric field strength of the channel that is currently communicating with the base station, and when the measurement result falls below the reference level, uses an empty time slot other than the time slot used for communication, and Of the control channel of the base station to be measured. Based on the change in the measurement result, the mobile station can know to which wireless zone the mobile station is moving (the mobile station can know the destination base station).

Subsequently, the mobile station transmits a handover request to the base station with which it is currently communicating. Thereby, the base station notifies the control station of the handover request. Based on the request, the control station checks an available communication channel and a time slot of the destination base station. In addition to notifying the slot, the mobile station notifies the destination base station that the mobile device will be handed over.

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

[Problems to be solved by the invention]

As the number of mobile communication system subscribers is increasing and the use of micro-cells in the wireless zone is progressing, especially in urban areas, the usage rate of mobile devices has temporarily increased only in specific wireless zones, There may be a case where a free communication channel exists in the wireless zone.

In such a case, in the above-described conventional mobile communication system, the mobile station does not output a handover request unless the electric field strength of the channel currently communicating with the base station is lower than the reference level. New outgoing calls and incoming calls of the mobile station located in the zone are ignored because there is no available channel, and the service cannot be received.

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

[Means for solving the problem]

FIG. 1 shows a principle configuration diagram of a mobile communication system according to the present invention. As shown in FIG.
12 ₁ base station 13 ₁ to 13 _n arranged in each to 12 _n, and controlled by the control station 11 a plurality of radio zones 12 ₁ to 12 _n as a single control zone, originating from the mobile station 14 ₁₁ to 14 _nm Call request to mobile station 14 ₁₁ ~
The control station 11 notified from the base station in the radio zone where the 14 _nm is located transmits a handover switching reference level to the control station 11 in the mobile communication system that specifies a communication channel to be used for the base station. means 15 is provided, also to each of the mobile station 14 ₁₁ to 14 _nm is received handover switching reference level and comparing means for comparing the current received field strength
And 16 ₁₁ ~ 16 _nm, is obtained by configured to have a handover request means 17 ₁₁ to 17 _nm.

Here, the handover switching reference level transmitting unit 15, the utilization of the communication channel is monitored for each of a plurality of radio zones 12 ₁ to 12 _n, handover switching reference level set values according to usage The multiple base stations 13 ₁
And transmits to the mobile station 14 ₁₁ to 14 _nm through to 13 _n.

Also, the handover request means 17 ₁₁ to 17 _nm, when the received field strength by the comparison means 16 ₁₁ ~ 16 _nm is received handover switching reference level small is that the comparison result from is obtained, a radio currently serving Measure the received electric field strength of the control channel transmitted from the base station in the wireless zone around the zone, and based on the measurement result, handover request to the predetermined base station Transmit to base station.

The mobile device according to the present invention, a plurality of base stations 13 ₁ to 13 _n
However, in the case of adding the information from the handover switching reference level transmitting means 15 to the broadcast information of the control channel and transmitting the information, receiving the information of the control channel while waiting,
Comparing means for comparing the handover switching reference level in the reception information with the reception electric field strength of the control channel; and controlling each base station when the reception electric field strength of the control channel is smaller than the reception handover switching reference level. Scanning means for performing a scan for waiting for a control channel having the second highest reception electric field strength among the reception electric field strengths of the channels during standby.

[Action]

In the mobile communication system according to the present invention monitors the handover switching reference level transmitting unit 15 is a base station 13 ₁ to 13 _n utilization of communication channels in the control zones in the control station 11 (traffic), the information New wireless zone 12 ₁ to 1
A handover switching reference level is determined every 2 _n, and a handover switching reference level having a value higher than the current value is transmitted to a base station in a wireless zone having a high communication channel usage rate. By this means, among a plurality of mobile stations located in a wireless zone having a high usage rate of a communication channel, a mobile station located in a peripheral part of the wireless zone is handed over via the handover request means. You can ask for over. Therefore, in the present invention, since the size of the zone can be substantially reduced for the radio zone having a high usage rate, it is possible to secure an empty communication channel for a new call in the radio zone having a high usage rate. it can.

In the mobile device according to the present invention, among mobile devices located in a wireless zone having a high usage rate, a standby mobile device located in a peripheral portion of the zone receives a communication channel by a scanning unit. When the mobile station finds a control channel with the second highest received field strength among the field strengths and makes a new call, the mobile station 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 having an available communication channel, instead of a base station in a wireless zone having a high usage rate.

〔Example〕

FIG. 2 shows a system configuration diagram of one embodiment of the present invention.
In the figure, the same components as those of FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. In FIG. 2, the control station (hereinafter, CS
11) are three base stations (hereinafter, referred to as BS) 13 ₁ , 13 ₂
And controls the 13 _3. BS 13 ₁ , 13 ₂ and 13 ₃ have wireless zones 12 ₁ , 12 ₂ and 12 ₃ , respectively, and perform wireless communication with mobile stations (hereinafter abbreviated as MS) on control channels and communication channels at mutually different frequencies. Do. However, wireless zones 12 ₁ , 12 ₂ ,
13 In ₃ both, T in one frequency in the same radio zone
Wireless communication is performed by the DMA method.

Now, as shown in FIG. 2, the radio zone 12 in _1, 1
One mobile station (MS) 14 ₁₁ -14 ₁₁₁ is located, of which MS 14
_{11-14 110} in communication with BS13 _1, assumed to be in standby is MS 14 _111. Also, MS 14 is in radio zone 12 _{2 21,} 14
_15, 14 ₁₆ and 14 ₁₇ within the area covered by a of which MS 14 ₂₁ is in communication with BS13 _2, MS 14 is in radio zone 12 _{3 31,} 14 _18, 14 _19, 14
₁₁₀ is visiting, of which MS 14 ₂₁ is assumed to be communicating with BS13 _3.

Furthermore, while the radio communication between the radio zone 12 within ₁ using all communication channels BS13 ₁ MS 14 ₁₁ to 14 ₁₁₀ and BS13 ₁ and is being performed, the radio zone 12 ₂ and 1 adjacent
3 fewer MS of _3, during communication, the BS13 _2, 13 ₃ each are present many vacant communication channels.

Next, the operation of each unit in the mobile communication system in such a state will be described with reference to FIG. If there is a call request from the MS, CS11
Upon receiving the request from the BS, it checks whether or not the BS has a free communication channel, and if so, specifies a communication channel to be used for the BS. On the other hand, when the switching network receives an incoming call to an MS in the control area, the CS 11 searches the location registration data for the wireless zone in which the MS is located, and
It is checked whether or not there is a free communication channel, and if there is, a communication channel is allocated to the BS.

Thus, CS11 is performed management of communication channels of each BS13 ₁ to 13 _3. Thus, CS11 is by monitoring the communication channel, in BS13 ₁ utilization of the communication channel is greater than a predetermined value, and, it can be seen that utilization of the communication channel BS13 ₂ and 13 ₃ is less than the predetermined value.

This allows CS11 to communicate with BS13 ₁ through BS13 _1.
14 with respect to ₁ to 14 _110, and sends the new handover switching reference level of a value higher than the current value (hereinafter referred to as "handover level") (of FIG. 3 step 101,10
2). At this time, the CS 11 does not have to send the handover switching reference level to the BSs 13 ₂ and 13 ₂ , but may send a new handover switching reference level having a lower value than the current value ( Step 10 in FIG.
3).

Radio zone 12 ₁ by the hand-over switching reference level is changed to a higher value, the broken line 1 in Figure 2
As indicated by 2 ₁ ′, the zone area becomes substantially narrower. Thus, BS13 ₁ and of the MS 14 ₁₁ to 14 ₁₁₀ in communication, is located in the radio zone 12 ₁ is such that not visited the radio zone 12 ₁ ', located in the peripheral portion of the radio zones 12 ₁ MS14 ₁₅
In to 14 _110, is compared with the reception field strength of the new handover switching reference level and BS13 ₁ communication channels received (step 104 of FIG. 3), compared towards the reception field strength is lowered results (weak since determination) is obtained (step 105 of FIG. 3), MS 14 ₁₅ to 14 ₁₁₀ in order to check their destination, by using the idle time slots, the radio zone 12 ₂ and 12 ₃ adjacent BS13 ₂ and the received signal strength of the control channel from 13 ₃ to measure (step 106 of FIG. 3).

The above results of measurement, MS 14 ₁₅ to 14 ₁₇ knows that the highest received field strength of the BS13 ₂ control channel, also MS 14 ₁₈
-14 ₁₁₀ knows that the highest received field strength of the control channel BS13 _3, transmits a handover request to the respective base station 13 _2, 13 ₃ to BS13 ₁ currently communicating (of FIG. 3 step 107 and 108 ).

CS11 Upon receiving the handover request from the MS 14 ₁₅ to 14 ₁₁₀ through BS13 ₁ (step 109 of FIG. 3), MS 14 ₁₅
-14 performs specified BS13 ₂ communication channels through BS13 ₁ for _17, through BS13 ₁ for MS 14 ₁₈ to 14 ₁₁₀
BS13 ₃ of performing the specified communication channel (step 110 and 111 of FIG. 3). Further, CS11 for destination BS13 _2, 13 ₃
The MS 14 _{15 to} 14 ₁₇ and the MS 14 _{18 to} 14 ₁₁₀ notify that a handover will occur (step 112 in FIG. 3). Thus, BS13 _2, 13 ₃ performs the transmission of the loop pending verification against _{MS14 15 ~14 17, MS14 18 ~14} 110 ( FIG. 3 step 11
3).

_{MS14 15 ~14 17, 14 18 ~14} 110 After performing channel designation data received in response to CS11 through BS13 ₁ (step 114 and 115 of FIG. 3), the channel switching to the communication channel of the new BS13 _2, 13 ₃ designated (Step 11 in FIG. 3)
6). Thereafter, the loop check return between the MS 14 ₁₅ to 14 ₁₇ is BS13 _2, also the loop check return between the MS 14 ₁₈ to 14 ₁₁₀ is BS13 _3, BS13 _2, 13 ₃ through performed in CS11 (Third FIG steps 117 and 118), and continues the radio communication with the BS13 _2, 13 ₃ (Fig. 3 step 119). On the other hand, when the CS11 receives the loop check return of the performs channel opening instruction to BS13 ₁ (FIG. 3 step 120).

Thus, since BS13 ₁ six vacant communication channel is generated, idle communication channel can not communicate without far, the MS 14 ₁₁₁ located near the BS13 _1, BS13 ₁
Communication becomes possible via the.

It should be noted that, as shown in step 101 and 103 of FIG. 3, while monitoring the usage of the communication channel for the entire zone CS11 may transmit dynamically to all BS13 ₁ to 13 ₃ handover switching reference level, also using the If the level is specified variably according to the rate, a better system can be constructed.

In the above embodiment notifies the handover switching the reference level in the communication channel to the MS in communication, thereby achieving effective utilization of the communication channel at high radio zone 12 _1-utilized in the communication channels, The present invention is not limited to this.
An instruction 11, BS13 ₁ to to 13 ₃ of the control channel information by adding a handover switching the reference level information of the communication channel of the radio zone, may be notified to the MS in the wireless zone.

Next, the operation of the mobile station in such a mobile communication system will be described with reference to the flowchart of FIG. First, among the mobile devices that are waiting, the mobile device that is to start a new communication knows the wireless zone in which it is located.
The control channels assigned to the entire system are scanned, and the scan is fixed to the control channel having the highest electric field strength after scanning (step 201). Subsequently, it is checked whether or not the handover switching reference level has been received in the received information of the control channel (step 202). If received, it is checked whether or not the value is greater than the received field strength of the current control channel (step 203).

Among the mobile stations located in the wireless zone where the usage rate of the communication channel is high, the mobile station located in the periphery of the wireless zone may have a received electric field strength lower than the handover switching reference level. Measures the received field strength of the control channel from each base station including the wireless zone adjacent to the wireless zone, and fixes it to the control channel with the second highest received field strength (step 204).
As a result, the mobile station changes and fixes the control channel having the highest received electric field strength to the second highest control channel.

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

According to the mobile station having such a configuration, if the mobile station (MS) 14 ₁₁₀ shown in FIG.
S14 ₁₁₀ has the second highest reception electric field strength while waiting
Fixed to the control channel from BS13 _3, thereby performing a call request to BS13 _3. Thus, according to this embodiment, the mobile station, such as 14 ₁₁₀ traffic is located in a high radio zone 12 ₁ can more efficiently use the communication channel.

〔The invention's effect〕

As described above, according to the mobile communication system of the present invention, by substantially reducing the radio zone with a high usage rate, a free communication channel can be secured for a new call in the radio zone. Channels can be effectively assigned, and according to the mobile station of the present invention, when the mobile station is located in a peripheral portion in a high-use rate radio zone,
A call request can be made with a fixed control channel at the time of waiting for a base station in a wireless zone having an adjacent free communication channel, so that communication can be performed over the free communication channel by efficiently using the communication channel. It has the feature of.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of the present invention, FIG. 2 is a diagram illustrating a system according to an embodiment of the present invention, FIG. 3 is a diagram illustrating a sequence according to an embodiment of the present invention, and FIG. FIG. 5 is a flowchart for explaining the operation of one embodiment, and FIG. In FIG, 11 ...... control station _{(CS), 12 1 ~12 n} ...... radio zone, 13 ₁ to 13 _n ...... base station _{(BS), 14 11 ~14 nm} ...... mobile station (MS), 15 ... ... indicates handover switching reference level transmitting unit, 16 ₁₁ ~16 _nm ...... comparing means, the 17 ₁₁ ~17 _nm ...... handover request means.

Claims (4)

(57) [Claims] 1. A plurality of radio zones (12 ₁ to 12 _n) base station for each of the (13 ₁ to 13 _n) arranged, radio zones of the plurality of (12 ₁ to 1
2 _n) is controlled by a control station (11) as one control zone, the mobile station (14 ₁₁ mobile equipment a call request from to 14 _nm) (14 ₁₁ to 14 _nm) is within the radio zone serving base said control station notified from the station, in a mobile communication system for specifying a communication channel to be used for that base station, the control station (11), said plurality of radio zones (12 ₁ to 1
Each the utilization of the communication channel of the 2 _n) monitor, set the handover switching reference level value in accordance with said use rate, it the plurality of base stations (13 ₁ ~13 _n) through a plurality of mobile stations a handover switching reference level transmitting unit that transmits to the _{(14 11 ~14 nm) (15} ), said plurality of mobile stations (14 ₁₁ ~14 _nm) the handover switching reference level received and the current receiving field and comparison means for comparing the intensity (16 ₁₁ ~16 _nm), when the comparison the received electric field strength is smaller than the receiving handover switching reference level results were obtained by the comparison means (16 ₁₁ ~16 _nm) Measures the received field strength of the control channel in the wireless zone around the currently located wireless zone, and based on the measurement result, issues a handover request to a predetermined base station in the currently located wireless zone. To send to the base station Mobile communication system, comprising the over-requesting means (17 ₁₁ ~17 _nm). 2. The plurality of base stations (13 _{1 to} 13 _n ) add information from the handover switching reference level transmitting means (15) to information of a communication channel and add the information to the mobile station currently communicating. transmitted to the comparing means (16 ₁₁ ~16 _nm) compares with the handover switching reference level received and the received field strength of the currently communicating, the handover request means (17 ₁₁ ~17 _nm) is Measuring a received electric field strength from a base station in the vicinity of the base station currently communicating, and transmitting a handover request to the base station currently communicating with the base station showing the highest received electric field strength. The mobile communication system according to claim 1. 3. The plurality of base stations (13 _{1 to} 13 _n ) add information from the handover switching reference level transmitting means (15) to control channel broadcast information and transmit the broadcast information. The mobile communication system according to claim 1. 4. A mobile station operating in the mobile communication system according to claim 3, wherein the mobile station receives information on a control channel while waiting, and receives the handover switching reference level and the control channel information in the received information. Comparing means (202, 203) for comparing the received electric field strength with the received radio field strength, when the comparison means (202, 203) obtains a comparison result in which the received electric field strength is smaller than the reception handover switching reference level, Scanning means (204) for measuring the reception electric field strength of the control channel from each base station in the wireless zone in the vicinity thereof and performing a scan for waiting for the control channel having the second highest reception electric field strength during standby. A mobile device comprising: