JP2833591B2 - Interference mitigation in mobile radio communication systems. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for reducing radio interference between a mobile station and a base station in a cellular mobile communication system, and more particularly to a communication system for controlling transmission power of a mobile station.

[0002]

2. Description of the Related Art In the field of mobile communications, in order to use radio frequencies effectively, it is necessary to divide a service area into several radio zones and reuse the same frequency repeatedly in a remote radio zone. Is being done. When the same frequency is repeatedly used in this manner, in a plurality of wireless zones in which the same frequency is allocated, if the respective channels of the same frequency are used, the base station can use the same frequency even between remote wireless zones. Interference occurs when receiving. In order to solve this problem, a method of measuring the reception level during a call and controlling the transmission power of the mobile station has been used.

[0003]

In the above-mentioned conventional cellular mobile communication system, when a mobile station starts communication from a particularly visible high place such as a building rooftop or a hill, the mobile station transmits a signal to the base station. A call signal to a station causes radio interference to nearby base station receivers using the same frequency traffic channel. However, there is a problem that interference cannot be reduced in the range of transmission power that can be controlled by the conventional transmission power control method.

[0004] The reason is that in the conventional cellular mobile communication system, the frequency is reused in order to use the radio frequency effectively, and when the mobile station starts communication under the condition of the conventional technology, A calling signal transmitted from a mobile station is received by a wide range of base stations. However, in the conventional transmission power control method, the range of controllable transmission power is not set on the assumption that it is used under these conditions. is there.

An object of the present invention is to reduce radio wave interference between a mobile station and a base station in a cellular mobile communication system.

[0006]

According to the present invention, there is provided an interference mitigation system in a mobile radio communication system, comprising: means for measuring reception levels of a control channel and a communication channel during communication; and a mobile station facing the mobile station in accordance with the measured reception levels. Means for requesting control of the transmission power of each of the plurality of first control channels, each of which is assigned the control channel of the same frequency.
A mobile station comprising means for controlling the transmission power of the base station, a mobile station comprising an exchange, and performing frequency reuse and handoff, wherein the mobile station has particularly good visibility. When communication is started from a high place and the plurality of first base stations receive a call signal transmitted from the same mobile station, the plurality of first base stations each receive the call signal. Notifying the switch of the level of the call signal, the switch identifies a serving base station that is a base station that controls the mobile station from among the plurality of first base stations, and uses the switching base station to control the serving base station. Requesting a first process for starting communication and a second process for reducing the output of the communication signal transmission power of the mobile station to a minimum within a communicable range, and from the serving base station to the mobile station. Requesting the first processing and the second processing, and the mobile station executing the second processing , To reduce the interference from the mobile station to the second base station neighboring the use of vent talk channel with the same frequency as the competent base station.

The interference mitigation method in the mobile radio communication system according to the present invention is characterized in that, when the exchange specifies the serving base station, the reception level of the calling signal broadcast from each of the plurality of first base stations is specified. , The first base station that has notified the call signal having the highest level among the compared call signals can be specified as the serving base station.

[0008] As described above, the call signal transmitted from the mobile station is monitored, and the plurality of first base stations to which the control channel of the same frequency is allocated transmits the call signal transmitted from the same mobile station. When receiving, the transmission power of the mobile station is set to a value larger than the range that can be controlled by the conventional transmission power control method, and the transmission power is controlled to be reduced to the minimum within the range in which communication is possible. It is possible to reduce radio wave interference to a nearby base station using the same frequency communication channel.

[0009]

Next, embodiments of the present invention will be described in detail with reference to the drawings.

[1] Description of Configuration First, a configuration of an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a diagram showing a configuration of a cellular mobile communication system according to an embodiment of the present invention. Here, it is assumed that the mobile station 5 shown in FIG. 1 is in a zone under the jurisdiction of the base station 2 in advance.

The cellular mobile communication system shown in FIG.
An exchange 1 for a cellular mobile communication system, a base station 2,
The configuration includes a base station 3 to which a control channel of the same frequency as the base station 2 is allocated, a nearby base station 4 to which a communication channel of the same frequency as the base station 2 is allocated, and a mobile station 5. The base stations 2 to 4 are connected to the exchange 1.

The exchange 1 compares the reception levels of the calling signals of the mobile station 5 broadcast from the base stations 2 to 4, and detects the base station that has received the highest level of the calling signal (here, the base station). 2) and a function of requesting a reduction in the transmission power of the communication signal of the mobile station 5. The base stations 2 to 4 receive and measure a call signal transmitted from the mobile station 5, report a measurement value of the received call signal to the exchange 1, and communicate with the exchange 1. A function of transmitting to the mobile station 5 a start request and a request to reduce the call signal transmission power of the mobile station. The mobile station 5 has a function of controlling the transmission power according to the request for reducing the transmission signal transmission power transmitted from the base station 2 based on the request for reducing the transmission signal transmission power of the exchange 1.

[2] Description of Operation Next, the operation of the embodiment of the present invention will be described with reference to FIG. 1 and FIG. FIG. 2 is a diagram showing a flow of processing of the cellular mobile communication system in one embodiment of the present invention.

When the mobile station 5 starts communication from a particularly visible high place such as the roof of a building or a hill (A1), the base station 2 and the base station 3 transmit a call signal transmitted from the mobile station 5. And measures the reception level of the received call signal (A2), and notifies the exchange 1 of the measured value of the reception level of each call signal (A3). The exchange 1 compares the measured values of the reception levels of the call signals notified from the base station 2 and the base station 3 (A4). As a result, it is specified that the mobile station 5 exists in the zone under the jurisdiction of the base station having the higher reception level (here, the base station 2).

Then, it requests the specified base station 2 to start communication (A5), and requests a reduction in the communication signal transmission power of the mobile station 5 (A6). The base station 2 that has received the communication start request and the call signal transmission power reduction request
Requesting the start of communication (A7), and requesting a reduction in the transmission power of the call signal (A8). The mobile station 5 reduces the communication signal transmission power to the minimum within the communicable range (A
9). By doing so, it is possible to reduce radio wave interference from the mobile station 5 to the nearby wireless base station 4.

[0016]

As described above, according to the present invention, when a mobile station starts communication from a particularly visible place such as a building rooftop or a hill, the communication signal transmission power of the mobile station is reduced. By reducing the transmission power to a value larger than the transmission power controllable by the transmission power control method and to a minimum within a communicable range, radio interference to neighboring base stations using a communication channel of the same frequency can be reduced. This has the effect of being able to reduce.

The reason is that a call signal transmitted from a mobile station is monitored, and a plurality of first base stations to which a control channel of the same frequency is assigned transmit a call signal transmitted from the same mobile station. By performing transmission power control to reduce the communication signal transmission power of the mobile station to a value larger than the range controllable by the conventional transmission power control method and to the minimum within the communicable range when received. This is because the transmission power of the communication signal of the mobile station decreases, and the reception level of the call signal transmitted from the mobile station decreases in each of the neighboring base stations using the communication channel of the same frequency.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a processing flow of the cellular mobile communication system in one embodiment of the present invention.

[Explanation of symbols]

 1 exchange 2, 3, 4 base station 5 mobile station

Claims (2)

(57) [Claims] 1. A communication system comprising: means for measuring reception levels of a control channel and a communication channel during communication; and means for requesting control of transmission power of an opposing mobile station in accordance with the measured reception levels. In a cellular mobile communication system including a plurality of first base stations to which the control channel is assigned, a mobile station including a unit that controls transmission power of the own station, and an exchange, the mobile station performs communication. Starting, when the plurality of first base stations receive a call signal transmitted from the same mobile station, each of the plurality of first base stations determines whether the received call signal is The switch informs the switch of the level, the switch specifies a serving base station that is a base station that controls the mobile station from among the plurality of first base stations, and communicates from the switch to the serving base station. First process to start And a second process for reducing the output of the communication signal transmission power of the mobile station to a minimum within a communicable range. The first process and the second process are performed by the serving base station to the mobile station. 2, the mobile station executes the second process, and transmits a radio wave from the mobile station to a nearby second base station using the same communication channel as that of the serving base station. An interference mitigation method in a mobile radio communication system, which reduces interference. 2. The communication system according to claim 1, wherein when the exchange specifies the serving base station, the reception levels of the call signals broadcast from each of the plurality of first base stations are compared. 2. The interference mitigation method in the mobile radio communication system according to claim 1, wherein the first base station that has broadcasted the highest-level calling signal is specified as the serving base station.