JPH10276463A - Mobile radio communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a mobile radio communication system which always executes appropriate hand-off processing that corresponds to traffic and surely reduces loss probability. SOLUTION: When a mobile station 42 measures the receiving electric field intensity of a carrier from a base station 21C, also, an exchange 50 measures the traffic of each base station 21A to 21E and 22A to 22E and the hand-off processing of the mobile station is controlled based on measurement data of measured receiving electric field intensity of the mobile station, the threshold that starts the hand-off processing is changed in accordance with the traffic of the base station 21C or 21D which is related to the hand-off.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile station which moves within a service area formed by a plurality of radio zones each covered by a base station, and performs call processing of the mobile station.
The present invention relates to a mobile radio communication system controlled by an exchange via a base station control device that controls a base station, and more particularly to control of handoff between radio zones of the mobile station.

[0002]

2. Description of the Related Art FIG.
FIG. 1 is a system configuration diagram showing a conventional mobile radio communication system disclosed in Japanese Patent Publication No. In the figure, 11A to 11E and 12A to 12E are a plurality of wireless zones, 21A to 21E.
And 22A to 22E are wireless zones 11A to 11E,
Base stations covering 12A to 12E, 31 and 32 denote base station controllers controlling base stations 21A to 21E and 22A to 22E, and 41 and 42 denote respective wireless zones 11A to 11E.
E, a mobile station that moves between 12A to 12E, 50 is an exchange that controls the base station controllers 31 and 32 and performs call processing for the mobile stations 41 and 42.

Next, the operation will be described. The mobile station 42 receives the radio wave from the base station 21C and the base station 21D adjacent thereto.
, And periodically reports to the base station 21C. The base station 21C relays the measurement data of the received electric field strength transmitted from each of the mobile stations 41 and 42 moving in the covered radio zone 11C to the base station controller 31. The base station controller 31 controls each of the base stations 21A to 21E.
Received received field strength measurement data sent from the mobile station, and for each mobile station, the received electric field between the base station that is talking using the channel of that station and the handoff destination base station adjacent to the base station The intensity difference is calculated and recorded and stored in a built-in recording table.

Here, for example, when traffic overload occurs in the base station 21C, the exchange 50
Upon detecting this, the base station controller 31 requests the base station controller 31 to notify a forced handoff candidate for forcibly executing a handoff. The base station control device 31 having received this request refers to the recording table and determines which of the mobile stations 41 and 42 in the radio zone 11C covered by the base station 21C can be handed off from the base station 21C. A mobile station having the smallest difference between the received electric field strength of the radio wave (carrier wave) and the received electric field strength of the radio wave from the adjacent base station that is a handoff destination is searched for, and the mobile station is reported to the exchange 50 as a candidate for forced handoff. .

As a candidate for the forced handoff, the one with the smallest difference is selected among the mobile stations that can be handed off. A nearby mobile station (mobile station 42 in the case shown) is selected as a candidate. The exchange 50 that has received the report forcibly executes the handoff process for the mobile station 42. Thereby, the connection of the mobile station 42 is switched from the base station 21C to the base station 21D, and the overload of traffic in the base station 21C is eliminated.

[0006]

Since the conventional mobile radio communication system is configured as described above, the base station 21
When traffic overload occurs in C, only the difference between the received electric field strengths of the radio waves from the base station 21C and the adjacent base station 21D of the mobile stations 41 and 42 that are communicating via the base station 21C is determined. Since a forced handoff process is performed based on the above, an appropriate handoff process depending on traffic may not be performed, and there has been a problem that the call loss rate cannot be reliably reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems. A mobile radio capable of always executing an appropriate handoff process according to traffic and reliably reducing a call loss rate. The aim is to obtain a communication system.

[0008]

According to a first aspect of the present invention, there is provided a mobile radio communication system in which a mobile station measures a received electric field strength of a carrier wave from a base station, and the received electric field strength of the carrier wave measured by the mobile station. When controlling handoff of a mobile station during a call based on the measurement data of the base station, the threshold value of the received electric field strength is changed according to the traffic of the base station related to the handoff measured by the exchange. Things.

In the mobile radio communication system according to the second aspect of the present invention, the control of the handoff is performed based on the deterioration of the measurement data of the received electric field intensity of the carrier wave from the base station used by the mobile station for communication, The threshold for judging the deterioration of the measurement data of the received electric field strength is changed so as to be high when the traffic of the base station is large and to be low when the traffic of the base station is small.

In the mobile radio communication system according to the third aspect of the present invention, the handoff control is performed when the reception electric field strength from a base station adjacent to the base station used by the mobile station for communication is adjusted to the reception electric field strength at the handoff destination. The threshold for determining whether the received electric field strength is sufficient as the reception electric field of the handoff destination is high when the traffic of the adjacent base station is large, and when the traffic is small, It is made to change so that it may become low.

In the mobile radio communication system according to the present invention, the base station measures the received field strength of the carrier from each mobile station, and the base station measures the received field strength of the carrier from each mobile station. When controlling handoff of a mobile station during a call based on the measurement data of the base station, the threshold value of the received electric field strength is changed according to the traffic of the base station related to the handoff measured by the exchange. Things.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. FIG. 1 is a system configuration diagram showing a mobile radio communication system according to Embodiment 1 of the present invention. In the figure, 11A to 11E and 12A to 12E are a plurality of radio zones forming a service area of the mobile radio communication system, and 21A to 21E are radio zones 1
Base stations that cover each of 1A to 11E with a predetermined transmission quality, 22A to 22E are wireless zones 12A to 12E.
E are base stations that cover each of E with a predetermined transmission quality. 31 is a base station controller that controls the base stations 21A to 21E, and 32 is a base station controller that controls the base stations 22A to 22E. These are the parts corresponding to those of the related art shown with the same reference numerals in FIG.

Reference numeral 42 denotes each of the wireless zones 11A to 11E.
And a mobile station that moves within the service area of the mobile radio communication system formed by
a is a radio wave (carrier) from the base station 21C which is arranged in the mobile station 42 and used by the mobile station 42 for communication.
This is a base station electric field strength measuring device for measuring the reception electric field strength of the radio wave from the base station 21D and the like which is a handoff destination adjacent to the base station 21C. Reference numeral 50 denotes an exchange which controls the base station controllers 31 and 32 and executes call processing of the mobile station 42 and the like to control handoff thereof. Reference numeral 5a is disposed in the exchange 50 and includes base stations 21A to 21A. This is a traffic measuring device that measures the traffic of each of 21E and 22A to 22E. In addition,
The mobile station 42 and the exchange 50 are different from the conventional ones shown by the same reference numerals in FIG. 5 in that they have a base station electric field strength measuring device 4a or a traffic measuring device 5a.

Next, the operation will be described. The mobile station 42 uses the built-in base station electric field strength measuring device 4a to cover the base station 21 covering the radio zone 11C where the mobile station 42 is located.
In addition to measuring the received electric field strength of the carrier wave transmitted from C, the base station 21D covering the wireless zone 11D which is a handoff destination adjacent thereto is identified, and the base station 21D is transmitted from the adjacent base station 21D. The received electric field strength of the carrier is also measured, and the measured data is periodically reported to the base station 21C. Similarly, the other mobile stations measure the received electric field strength and periodically report the measured data to the corresponding base station. The base stations 21A to 21E transmit to the base station controller 31 measurement data of the received electric field strength transmitted from the mobile stations moving in the radio zones 11A to 11E covered by the base stations 21A to 21E, respectively. The relay station relays the measurement data of the received electric field strength transmitted from the mobile station moving in the wireless zones 12A to 12E covered by the base station control device 32, respectively.

Further, the base station control device 31 transmits information to the base station 21A.
To 21E and the base stations 21A to 2E.
1E, the base station controller 32 receives the measurement data of the received electric field strength for each mobile station,
A to 22E and the base stations 22A to 22E.
The measurement data of the received electric field strength for each mobile station transmitted from 22E is received. The exchange 50 controls the base station controllers 31 and 32 to execute a handoff process based on the measurement data, to change the connection of the base station with which the mobile station that is talking is communicating, and to store the built-in traffic. Using the measuring device 5a, the traffic of each of the base stations 21A to 21E and 22A to 22E is measured, and the measurement result is notified to the base station controllers 31 and 32.

Here, during a call using the channel of the base station 21C, the mobile station 42 moving in the radio zone 11C,
Consider a case where the measurement data of the received electric field strength of the carrier wave transmitted by the base station 21C approaches the boundary of the wireless zone and deteriorates.

The mobile station 42 uses the base station field strength measuring device 4a to transmit the received field strength of the carrier from the base station 21C used by the mobile station 42 for communication and the base station 21C identified as the handoff destination. Adjacent base station 2
Measure the received field strength of the carrier from 1D. The measurement data of the received electric field strength is periodically reported to the base station 21C, and the base station 21C relays it to the base station controller 31. On the other hand, the exchange 50 is connected to each of the base stations 21A to 21E and 22A to 22E by the traffic measuring device 5a.
Each traffic is transmitted to each base station 2
It is measured as a value divided by the number of channels 1A to 21E and 22A to 22E, and is notified to the base station controller 32 or 32, respectively.

The base station controller 31 transmits the measurement data of the received electric field strength of the carrier wave from the base station 21C to the mobile station 42 during a call using the channel of the base station 21C sent from the base station 21C. And a threshold value for determining whether or not the measurement data has deteriorated. As a result, when the measured data of the received electric field strength falls below this threshold value, it is determined that the measured data has deteriorated. Here, the threshold value for determining whether or not the measurement data has deteriorated is determined by the traffic measurement device 5a and transmitted from the exchange 50 to the base station 2.
It is controlled by 1C traffic. FIG. 2 is an explanatory diagram showing a change in the threshold value with respect to the traffic. The threshold value for judging whether or not the measurement data of the received electric field strength has deteriorated is a threshold value when the traffic of the base station 21C is large. Is high, and when the traffic is small, the threshold value is controlled to be low. Therefore, when the traffic of the base station 21C increases, it is determined that the measurement data has deteriorated even at a relatively high reception electric field strength. However, when the traffic is small, the measurement data deteriorates unless the reception electric field strength decreases to some extent. It is not determined that they have done so.

Here, according to the example shown in FIG. 2, the threshold value is controlled so as to continuously change in response to a change in traffic. For example, as shown in FIG. The threshold value may be controlled so as to discretely change for each range.

In this manner, the measured data of the received electric field strength from the base station 21C used by the mobile station 42 for the call becomes lower than the threshold value, and the measured data of the received electric field strength is deteriorated. When this is detected, the base station control device 31 determines whether or not to hand off the mobile station 42 from the wireless zone 11C to the adjacent wireless zone 11D. This determination is based on the measurement data of the received electric field strength of the carrier wave from the base station 21D, which is the handoff destination in the mobile station 42, and a threshold for judging whether the received electric field strength is sufficient as the handoff destination. This is done by comparison with the value. That is, if the measured data of the received electric field strength of the carrier wave from the base station 21D in the mobile station 42 is equal to or larger than the threshold value, the base station controller 31 requests the exchange 50 to perform a handoff of the mobile station 42. .
Upon receiving the request, the exchange 50 executes a handoff process for the mobile station 42, whereby the connection of the mobile station 42 is switched from the base station 21C to the base station 21D.

As described above, according to the first embodiment,
When performing a handoff control based on the deterioration of the measurement data of the received electric field strength of the carrier wave transmitted from the base station used by the mobile station for the call, to determine whether the measurement data has deteriorated. The threshold value is controlled such that when the traffic of the base station in use by the mobile station is large, the traffic is high and when the traffic is small, the low is low, so that the handoff of the mobile station from the base station with high traffic becomes easy. Thus, it is possible to perform the optimal control of the traffic distribution, thereby reducing the call blocking rate and effectively using the channel.

Embodiment 2 FIG. In the first embodiment, the threshold value for detecting that the measured data of the received electric field strength of the carrier wave from the base station used by the mobile station for communication has deteriorated is
Although described as being variable according to the traffic of the base station, the threshold value for determining whether the reception field strength from the adjacent base station is sufficient as the reception field strength at the handoff destination, It may be changed according to the traffic of the adjacent base station.

That is, the base station controller 31 first receives the electric field strength of the carrier wave transmitted from the base station 21C in the mobile station 42 during a call using the channel of the base station 21C sent from the base station 21C. Is compared with a threshold value for determining whether or not the measurement data has deteriorated, and it is determined whether or not the measurement data of the reception electric field strength has deteriorated. When the deterioration of the measurement data is detected, the base station control device 31 determines whether or not the mobile station 42 is handed off from the wireless zone 11C to the wireless zone 11D. This determination is based on the measurement data of the received electric field strength of the carrier wave from the base station 21D, which is the handoff destination in the mobile station 42, and a threshold for judging whether the received electric field strength is sufficient as the handoff destination. This is done by comparison with the value.

Here, the threshold value for determining whether or not the reception field strength at the handoff destination is sufficient is:
It is controlled by the traffic of the base station 21D, which is a handoff destination, measured by the traffic measuring device 5a and sent from the exchange 50. Also in this case, the threshold value for detecting whether the received electric field strength at the handoff destination is sufficient is, as shown in FIG. 2 or FIG.
Is controlled so that the threshold value becomes higher when the traffic is large, and the threshold value becomes lower when the traffic is small.

Therefore, when the traffic of the base station 21D increases, even if the received electric field intensity of the carrier wave from the base station 21D in the mobile station 42 is relatively high, it is sufficient as the received electric field intensity of the handoff destination. Is not determined, but if the traffic is small,
Even when the received field strength from the base station 21D is low to some extent, it is determined that the received field strength at the handoff destination is sufficient. If the measurement data of the received electric field strength of the carrier wave from the base station 21D in the mobile station 42 is equal to or more than such a threshold value, the base station control device 31 requests the exchange 50 to hand off the mobile station 42. Upon receiving the request, the exchange 50 executes a handoff process for the mobile station 42, whereby the connection of the mobile station 42 is switched from the base station 21C to the base station 21D.

It is to be noted that the threshold value for determining whether or not the reception electric field strength of the handoff destination is sufficient as described above is not only controlled according to the traffic of the base station to which the handoff is performed, but also is implemented. As described in the first embodiment, the threshold for determining whether or not the measurement data of the received electric field strength has deteriorated may be controlled according to the traffic of the base station used for the call.

As described above, according to the second embodiment,
Measurement data of the received electric field strength from the base station adjacent to the base station used by the mobile station for communication, when performing handoff control based on whether or not the received electric field strength of the handoff destination is sufficient, By controlling the threshold value for determining whether or not the received electric field strength of the handoff destination is sufficient when the traffic of the adjacent base station is large and low when the traffic of the adjacent base station is small, the base station with high traffic is controlled. This makes it difficult to perform a handoff of the mobile station to the mobile station, thereby making it possible to perform optimal control of the traffic distribution, reduce the call blocking rate, and effectively use the channel.

Embodiment 3 In each of the above embodiments, the case where the measurement data of the received electric field strength of the carrier wave from the base station is measured on each mobile station side, and the measurement data from each mobile station is relayed by the base station and sent to the base station control device However, the measurement data of the received electric field strength of the carrier wave from each mobile station may be measured by the base station, and the measurement data for each mobile station may be sent from the base station to the base station controller.

FIG. 4 shows such a third embodiment of the present invention.
FIG. 1 is a system configuration diagram showing a mobile radio communication system according to the first embodiment. In the figure, 2a is arranged in each of the base stations 21A to 21E and 22A to 22E,
This is a mobile station electric field intensity measuring device that measures the electric field intensity of a received radio wave (carrier) from the like. In FIG. 4, the mobile station electric field strength measuring device 2a is shown only in the base station 21C, and the description is omitted in other base stations.

Next, the operation will be described. In the first and second embodiments, the reception electric field strength of the base station 21C used by the mobile station 42 for communication and the base station 21D adjacent thereto is measured, and the measurement data is reported to the base station 21C. In the third embodiment, each of the base stations 21A to 21A is controlled by instructions from the base station controllers 31 and 32.
21E and 22A to 22E measure the received electric field strength of the carrier from the mobile station 42 in each base station. The measurement of the received electric field strength from the mobile station 42 in the base stations 21A to 21E and 22A to 22E is performed by the mobile station electric field strength measuring device 2a incorporated therein.

Each of the base stations 21A to 21E and 22A to 2
The measurement data of the received electric field strength of the carrier for each mobile station measured in 2E is sent to the base station controllers 31 and 32.
Each of the base station controllers 31 and 32 has a base station 21 measured by the traffic measuring device 5a of the exchange 50.
A to 21E and 22A to 22E traffic are also sent. Hereinafter, as in the case of Embodiment 1 or 2, the threshold value of the received electric field strength of the carrier for determining whether or not to perform the handoff of the mobile station 42 is set to the base station related to the handoff, that is, The base station 21C during which the mobile station 42 is using the call or the base station 21 adjacent to the base station 21C to which the mobile station 42 is to be handed off.
The handoff of the mobile station 42 between the radio zones 11C and 11D is controlled by changing the traffic according to the traffic of D.

As described above, according to the third embodiment,
Since the base station measures the received electric field strength of the carrier from each mobile station and transmits the measured data to the base station controller,
A threshold for determining whether the measurement data has deteriorated,
Alternatively, when performing handoff control by comparing with a threshold value for determining whether or not the reception electric field strength of the handoff destination is sufficient, each mobile station measures the reception electric field strength for each base station. This has the effect of eliminating the need to send data.

[0033]

As described above, according to the first aspect of the present invention, the mobile station measures the received electric field strength of the carrier from the base station, and based on the measured data, the handoff of the mobile station during a call. , The threshold value of the received electric field strength is controlled according to the traffic of the base station related to the handoff measured by the exchange. By raising the, during the transition to the wireless zone covered by another base station of the mobile station during a call, the transition is facilitated, and when transitioning from the wireless zone covered by another base station, Since the transition is difficult to perform, it is possible to optimally control the traffic distribution, and to reduce the call loss rate appropriately to enable effective use of the channel. There is an effect that Temu is obtained.

According to the second aspect of the present invention, the handoff control is performed based on the deterioration of the measurement data of the received electric field strength of the carrier wave from the base station used by the mobile station for communication,
When the traffic of the base station is large, the threshold value at that time is lowered, and when the traffic is small, the threshold value is set to be high. When performing handoff control based on the deterioration of the measurement data, it becomes easier to perform a handoff of the mobile station from a base station with high traffic to an adjacent base station, and optimal control of traffic distribution can be performed. There is an effect that the call blocking rate can be reduced and the channel can be effectively used.

According to the third aspect of the present invention, the handoff of the handoff is performed based on whether or not the received electric field strength from the base station adjacent to the base station used by the mobile station for the call is sufficient as the reception electric field at the handoff destination. When the traffic of the adjacent base station is large, the threshold at that time is set high, and when the traffic is small, the threshold is set low. When performing the handoff control based on whether or not the measurement data of the reception electric field strength of the reception electric field strength is sufficient as the reception electric field strength of the handoff destination, the handoff of the mobile station from the adjacent base station to the base station with high traffic is performed. This makes it possible to perform optimal control of traffic distribution, reduce the call blocking rate, and effectively utilize channels.

According to the fourth aspect of the present invention, the base station measures the received electric field strength of the carrier wave from each mobile station, and receives the signal when controlling the handoff of the mobile station during a call based on the measured data. Since the threshold of the electric field strength is configured to be changed according to the traffic of the base station related to the handoff measured by the exchange, the base station with a large traffic raises the threshold for performing the handoff so that the communication can be performed. When transitioning to a wireless zone covered by another base station of the mobile station, the transition is facilitated, and
When transitioning from a wireless zone covered by another base station, it is difficult to make the transition, so it is possible to optimally control the traffic distribution, and to appropriately reduce the call loss rate and achieve effective use of the channel. In addition to this, there is an effect that it is not necessary to transfer the measurement data of the received electric field strength from each mobile station to the base station in controlling the handoff.

[Brief description of the drawings]

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

FIG. 2 is an explanatory diagram showing an example of a change of a threshold value for determining whether or not to perform handoff according to the present invention with respect to traffic;

FIG. 3 is an explanatory diagram showing another example of a change of a threshold value for determining whether to perform handoff in the present invention with respect to traffic.

FIG. 4 is a system configuration diagram showing a mobile radio communication system according to a third embodiment of the present invention.

FIG. 5 is a system configuration diagram showing a conventional mobile radio communication system.

[Explanation of symbols]

2a Mobile station electric field strength measuring device, 4a Base station electric field strength measuring device, 5a Traffic measuring device, 11A-11
E, 12A to 12E wireless zone, 21A to 21E, 2
2A to 22E base station, 31, 32 base station controller,
42 mobile stations, 50 switches.

Claims (4)

[Claims] 1. A service area of the entire system is formed by a plurality of wireless zones, a plurality of base stations covering each of the wireless zones, and a plurality of wireless zones covered by each of the base stations. A mobile station that moves within a service area, a base station controller that controls the base station, and an exchange that controls the base station controller and performs call processing for the mobile station. The mobile station has a base station electric field strength measuring device for measuring a received electric field intensity of a carrier wave transmitted from the base station, and the exchange has a traffic measuring device for measuring traffic of each of the base stations. When controlling the handoff of the mobile station between the wireless zones based on the received electric field strength of the carrier measured by the mobile station, Mobile radio communication system, characterized in that the threshold value of the reception field strength of the carrier wave for determining whether to perform the hand-off is varied in accordance with the traffic of the base station related to the handoff. 2. A handoff control is performed based on whether or not measurement data of a received electric field strength of a carrier wave transmitted from a base station used by the mobile station for a call is degraded. 2. The mobile station according to claim 1, wherein a threshold value for determining whether or not the mobile station has deteriorated is changed in accordance with the traffic of the base station so as to be high when the traffic is large and low when the traffic is small. Wireless communication system. 3. The reception field strength measurement data from a base station adjacent to a base station used by the mobile station for a call,
Based on whether or not the reception electric field strength of the handoff destination is sufficient, the handoff control is performed, and the threshold value for determining whether or not the reception electric field strength of the handoff destination is sufficient is set to the adjacent threshold. 3. The mobile radio communication system according to claim 1, wherein the traffic is changed so as to be high when the traffic is large and low when the traffic is small, according to the traffic of the base station. 4. A service area of the entire system is formed by a plurality of wireless zones, and a plurality of base stations covering each of the wireless zones, and the plurality of wireless zones covered by each of the base stations are formed. A mobile station that moves within a service area, a base station controller that controls the base station, and an exchange that controls the base station controller and performs call processing for the mobile station. The base station has a mobile station electric field strength measuring device for measuring a received electric field intensity of a carrier wave transmitted from the mobile station, and the exchange has a traffic measuring device for measuring traffic of each of the base stations. The handoff of the mobile station between the radio zones, based on the received electric field strength of the carrier for each mobile station measured by the base station Controlling the threshold value of the received electric field strength of the carrier for determining whether or not to perform a handoff in accordance with the traffic of the base station related to the handoff. system.