JP3389503B2 - Base station equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a base station device for a radio telephone that adjusts the transmission output of a control channel.

[0002]

2. Description of the Related Art In recent years, PHS (Personal Handyphone S
In ystem), the call area has expanded greatly with the addition of base station equipment. When arranging base station equipment,
In order to efficiently cover a wider area with a minimum number of base station devices, it is ideal to arrange the base station devices regularly as shown in FIG. 5 (a).

However, under the present circumstances, it is difficult to regularly arrange the base station apparatus in an ideal location due to the influence of the terrain and buildings, and the size and shape of the wireless zone are different depending on the base station apparatus. It is difficult to arrange well. Further, in an area with a high traffic density such as a city, base station devices are densely arranged in order to cope with it. FIG. 5B shows an example of the arrangement of the base station devices in such a current situation.

From such a background, interference of control channels between adjacent base station devices has become a problem in recent years.
Here, the control channel is a control channel that is provided separately from the call channel (call channel), and is mainly used for service information and incoming information in the wireless zone, and for outgoing and location registration from mobile stations. It is used for notifying control information such as various signals.

The base station device, as shown in FIG.
A (Time Division Multiple Access) / TDD (Time
Division Duplex) 5ms TDMA / TD
The D frame is divided into 8 time slots for 625 μs each, and 4 time slots among them are used for upstream communication (mobile station →
It is possible to perform communication by assigning different time slots to a maximum of four mobile stations using the base station apparatus) channel and the remaining four time slots as downlink communication (base station apparatus → mobile station) channel. The base station device is
An integer multiple of the A / TDD frame, for example, 20 frames (100 ms) is set as an intermittent transmission cycle, and one cycle (80
One time slot for each transmission time slot) is assigned to a transmission time slot of a downlink control channel (hereinafter referred to as a downlink control slot), and intermittent transmission of control information and the like is performed.

Since the frequency of the control channel is common to all the base station devices, when adjacent base station devices output radio waves of the control channel in the same time slot, the wireless zones overlap as shown in FIG. 5 (c). Interference occurs in the shaded area. The mobile station located in this interference portion cannot receive the control channel and cannot talk.

In order to deal with this, in the conventional technique, the base station apparatus prevents the downlink control slot of the control channel from overlapping with the downlink control slots of other peripheral apparatuses in order to prevent the downlink control slot of the peripheral base station apparatus from changing in time slot units. The received signal level of the transmitted wave is measured, and the time slot with the lowest measured value is determined as the downlink control slot. By this method, the conventional base station apparatus avoids the interference of the control channel.

[0008]

However, even in the above-described control channel interference avoidance method in the prior art, since the number of time slots in one intermittent transmission cycle is limited, all time slots are downlink control slots of other devices. If it is assigned to, there is a problem of interference.

This interference does not occur only between adjacent base station devices. The size and shape of the wireless zone in the actual installation environment cannot be theoretically grasped.For example, when the wireless zone is installed on the roof of a building, the reach of radio waves may be unexpectedly long, which is unexpected. Interference has occurred. In addition to such a situation, in recent years, considering the situation where a base station device is added in order to cope with high traffic, the area where the control channel interferes (interference area) will continue to increase, and as a result, communication will increase. It is expected that the impossible area will increase.

In view of the above problems, it is an object of the present invention to provide a base station apparatus that reduces control channel interference.

[0011]

[0012]

The base station apparatus of the present invention comprises:
Others in the transmission time slot of the control channel of the own device
Measure the received signal level of the transmitted wave of the control channel of the device
Measuring means, the range of the received signal level and the control channel
Transmit power and transmit power as the range of received signal level increases
A table that corresponds to
Storage means for storing a plurality of data in the storage means and the storage means
Among the plurality of tables, a selection means for selecting one of the tables according to the environment of the apparatus, by using the selection tables, the received signal level measured by the measuring means
Specifying means for specifying the transmission output of the control channel to be output by the device itself according to the
The transmission output designated by the designating means.
A transmission means for transmitting a transmission wave of the channel may be provided .

Further, the selecting means includes an environment judging means for judging the installation environment according to the reception condition of the control channel from the peripheral base station device, and the table is selected using the judgment result of the environment judging means. You may comprise. Further, the measuring means is a transmission channel of the control channel of the own device.
In addition to the mobile slot, the reception signal level of the transmission wave of the control channel of the other device in each transmission time slot that can be assigned as the control channel of the own device is measured, and the environment determination means is the reception signal measured by the measurement means. It may be configured to include a counting unit that counts the number of levels exceeding a predetermined level and determine the installation environment according to the number counted by the counting unit.

The base station apparatus further includes demodulation means for demodulating a transmission wave of a control channel of another apparatus for all transmission time slots in which the control channel of the own apparatus can be transmitted, and the environment determination means includes the demodulation means. By the determination means for determining whether each transmission time slot is normally demodulated by, and the counting means for counting the number of normally demodulated by the determination means, the number counted by the counting means The installation environment may be determined accordingly.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION (First Embodiment) A base station apparatus according to the first embodiment of the present invention will be described below. FIG. 1 is a block diagram showing the configuration of the base station apparatus of this embodiment. In the figure, the base station device includes an antenna 10, a transmission / reception changeover switch 11, a transmission unit 12, a reception unit 13, a line unit 14, and a control unit 15.

The transmission / reception changeover switch 11 includes a control unit 15
It is a switch that switches between transmission and reception of the antenna 10 by TDD under the control of. The transmission unit 12 includes the modulation unit 12
1. The transmitter 122 is configured to convert a transmission signal into a modulation signal in the modulation unit 121 under the control of the control unit 15,
The transmitter 122 converts the signal into a high frequency signal, amplifies it, and outputs it via the antenna 10.

The transmitter 122 comprises a burst switch (not shown) for cutting out transmission time slots, a mixer (not shown) for converting to a transmission frequency, and a transmission output amplifier 122a. In particular, the transmission output amplifier 122a includes the control unit 15
The transmission output is made variable by the transmission output control signal. The receiver 13 includes a receiver 131, a demodulator 132, and an RS.
SI (received signal strength indicator) detector 1
The reception wave input from the antenna 10 is converted into an intermediate frequency signal by frequency conversion in the receiver 131, and demodulated in the demodulation unit 132 to be converted into a baseband signal.

The RSSI detector 133 is the strength of the received wave (electric field strength) input from the antenna 10 to the receiver 131.
Is detected for each time slot and is output to the transmission slot 151 as a received signal level. The line unit 14 is a digital network interface unit, which performs location registration, authentication, call connection, information exchange with a PHS management center, etc. under the control of the control unit 15, and a TDMA / TDD frame with another device. Synchronize timing.

The control unit 15 is composed of a microcomputer and ROM / RAM, and realizes various functions by reading and executing a program stored in the ROM. Particularly, the control unit 15 sets the transmission output of the control channel of the own device so that the higher the received signal level becomes, the smaller the transmission output becomes, according to the reception signal level of the transmission wave of the control channel of the other device in the downlink control slot of the own device. Control.

That is, the control unit 15 determines that the higher the received signal level of the other device is, the closer the wireless zone of the other device is to the own device, and reduces the transmission output of the own device to reduce the wireless output of the own device. The area of the zones is reduced to prevent interference due to overlapping wireless zones. In order to realize these, the control unit 15 includes a transmission slot selection unit 151, a transmission output determination unit 152, and a transmission output control unit 15
It consists of 3.

Prior to controlling the transmission output, the transmission slot selection section 151 selects the transmission time slot with the lowest possibility of interference from the 80 transmission time slots as the downlink control slot. Specifically, when the reception signal level of each time slot is input from the RSSI detector 133, the transmission slot selection unit 151 compares the reception signal levels of 80 transmission time slots in the intermittent transmission cycle of the control channel among them. Then, the transmission time slot having the lowest received signal level is selected as the downlink control slot.

The transmission slot selection section 151 notifies the transmission output control section 153 of the determined time slot number n of the downlink control slot, and notifies the transmission output determination section 152 of the received signal level r in that time slot. The transmission output determination unit 152 determines the transmission output of the downlink control slot according to the received signal level r input from the transmission slot selection unit 151.

The transmission output determination unit 152 internally stores the transmission output table 152 in order to determine the transmission output.
a is used. FIG. 2 is a diagram showing stored contents of the transmission output table 152a. As shown in the figure, the transmission output table 152a associates a plurality of reception signal level ranges and the transmission outputs of the control channels to be output in the ranges so that the higher the reception signal level is, the smaller the transmission output is.

When the transmission slot selection section 151 notifies the reception signal level r, the transmission output determination section 152 refers to the transmission output table 152a to find a corresponding reception signal level range, and the transmission output corresponding to the range. The transmission output control unit 153 is notified of p. For example, the transmission slot selection unit 151 sets the received signal level r to “23 dBμ
When "V" is notified, the transmission output determining unit 152 causes the transmission output table 152a to indicate the transmission output p "300 mW" corresponding to the range of the reception signal level of "20 to 30 dBμV".
To the transmission output control unit 153.

The transmission output control section 153 controls the transmission output of the transmission output amplifier 122a in the downlink control slot. More specifically, when the transmission slot selection unit 151 notifies the transmission output control unit 153 of the slot number n and the transmission output determination unit 152 notifies the transmission output p, the transmission wave of the control channel is transmitted to the time slot of the slot number n. At, the transmission output control signal is sent to the transmission output amplifier 122a so as to output the transmission output p.

With the above configuration, in the base station apparatus, the transmission slot selection section 151 selects the downlink control channel from the 80 transmission slots according to the received signal level of another apparatus, and receives the downlink control channel. The transmission output determination unit 152 is notified of the signal level, and the transmission output determination unit 152 determines the transmission output using the transmission output table 152a corresponding to the smaller transmission output for the higher reception signal level, and the transmission output control unit 153 determines. The transmission output amplifier 122a is controlled so as to be output with the generated transmission output.

With this configuration, when the wireless zones of other base stations existing in the vicinity of the base station apparatus are close to the own apparatus, the area of the wireless zone of the own apparatus is reduced to reduce the wireless Minimize zone overlap, which reduces control channel interference. (Second Embodiment) A base station apparatus according to the second embodiment will be described below.

FIG. 3 is a block diagram showing the configuration of the base station apparatus of this embodiment. In the figure, the base station device is configured to change the transmission output according to the received signal level as in the first embodiment, and is also configured to control the transmission output according to the installation environment of the base station device. To be done. In this embodiment, the installation environment refers to a high installation density of peripheral base station devices in the installation area of the base station device. For example, in a low traffic area such as the suburbs, the installation density of the base station devices is low, so that one base station device needs to increase the wireless zone by a larger transmission output to cover the area. On the other hand, in a high traffic area such as an urban area, since the installation density of base station devices is high and the interference is likely to occur, it is necessary to reduce the transmission output to reduce the occurrence of the interference.

The base station apparatus of the present embodiment determines the installation environment of the base station apparatus and flexibly changes the transmission output in accordance with the determined installation environment and the received signal level to prevent occurrence of interference. Configured to reduce. For this reason,
The base station apparatus of FIG. 3 includes a control unit 16 instead of the control unit 15 in FIG. 1, and the internal configuration of the control unit 16 is partially different from the control unit 15. In FIG. 3, components having the same reference numerals as those in FIG. 1 have the same functions, and therefore description thereof will be omitted, and different components will be described below.

The control unit 16 of this base station apparatus includes a transmission slot selection unit 151, an environment determination unit 161, and a transmission output determination unit 1.
62 and a transmission output control unit 153. The environment determination unit 161 stores the demodulated signal of the control channel of the other device input from the demodulation unit 132 and the received signal level of the control channel of the other device in the 80 transmission slots input from the RSSI detector 133. Then, the installation environment is determined according to the reception status thereof, and the table selection unit 163 is notified.

In the present embodiment, the installation environment is classified into three categories of "A", "B", and "C" in the order of low installation density, middle installation, and high installation density. Which of the three categories corresponds to is determined. First, when the number of slots in which the received signal level of the control channel of the other device exceeds the predetermined level is less than the first predetermined number among the 80 transmission time slots, it is classified as “A”. Here, the predetermined level refers to the maximum value of the level that the base station apparatus can use as a downlink control slot without causing interference.

Further, if the received signal level exceeds a predetermined level, and if the number of those normally demodulated by the demodulation unit 132 in those slots is less than the second predetermined number, it is classified as "B" and the second predetermined number. "C" if more than
Is determined. The normally demodulated number means how many other base station devices the wireless device is installed in.

More specifically, the environment determination unit 161 uses the RSSI
A predetermined level of the received signal level of the control channel of the other device detected by the detector 133 (for example, 40 dBμ
It is determined whether or not the number of slots exceeding V) is equal to or larger than a first predetermined number (for example, 4), and if less than 4, it is determined to be “A” and notified to the table selection unit 163. Judgment result,
If the number of slots exceeding the predetermined level is four or more, the environment determination unit 161 further counts the number of transmission waves of the control channel demodulated normally from the input of the demodulation unit 132, and the number is the second predetermined number. "B" if less than (eg 4)
The table selection unit 163 is notified, and when it is determined that the number is the second predetermined number or more, it is determined as “C” and the table selection unit 163 is notified.

The transmission output determination unit 162 is the environment determination unit 16
Installation environment and transmission slot selection unit 1 determined by 1
The transmission output of the downlink control slot is determined according to the received signal level r input from S51. Therefore, the transmission output determination unit 162 includes a table selection unit 163 and a transmission output table 162a.

The table selection unit 163 is the environment determination unit 16
According to the installation environments A, B, and C determined by No. 1, the transmission output determination unit 161 selects a table used for transmission output determination from the transmission output tables 162a, 162b, 162c. Figure 4
FIG. 6 is a diagram showing stored contents of transmission output tables 162a, b, c. In the figure, the transmission output table 162a,
Although b and c are commonly associated with each other so that the higher the received signal level is, the smaller the transmitted output is, the transmitted outputs corresponding to the range of the received signal level are different.

That is, the transmission output tables 162a, 162b,
c is 162b rather than 162a and 162 more than 162b
For c, as the range of the received signal level becomes higher,
It is adapted so that the transmission output becomes smaller. When the environment determining unit 161 determines that the installation environment is “A”, the table selecting unit 163 transmits the transmission output table 162.
If you select a and the installation environment is determined to be "B",
Select the transmission output table 162b, and the installation environment is "C"
When it is determined that the transmission output table 162c is selected, the transmission output determination unit 162 determines the transmission output according to the reception signal level r input from the transmission slot selection unit using the selected table. .

As a result, the base station apparatus covers a wide area by preventing the transmission output from being lowered too much in an area with a low installation density, and has a high received signal level in an area with a high installation density. As a result, the transmission output is greatly reduced to prevent interference.

[0038]

The base station apparatus of the present invention is a control station of its own apparatus.
For each transmission time slot that can be assigned for channels
Takes a measurement unit for measuring a received signal level of the transmission wave of the control channel of another system, one transmission Times every predetermined time period
Lots transmit time slot for own device control channel
The means for selecting the
Received signal level of each transmission time slot during a predetermined period
And the transmit time slot with the lowest received signal level.
Selected as the transmission time slot for the control channel.
Time slot selection means to select, and the selected transmission
Specifying means for specifying the transmission output of the control channel to be output from the device itself in the time slot, such that the transmission output becomes smaller as the received signal level becomes higher ;
And transmitting means for transmitting the transmission wave of the control channel at the designated transmission output in the designated transmission time slot.

With this configuration, the base station apparatus of the present invention has a higher transmission signal of the control channel of its own apparatus as the received signal level of the control channel of the other apparatus is higher in the transmission time slot of the control channel of its own apparatus. When the wireless zone of another device is closer to its own device, the wireless zone of its own device is made smaller, and the area of the interference area due to the overlapping of the wireless zones is made smaller. Therefore, there is an effect that interference can be reduced.

Further, the base station apparatus of the present invention has the effect of saving transmission power because the transmission output is reduced when an interference area occurs. The designation means is
A storage means is provided for storing a table in which a plurality of reception signal level ranges and control channel transmission outputs to be output in the range are associated with each other so that a higher reception signal level has a smaller transmission output. It may be configured to specify the transmission output by using.

As described above, in the base station apparatus of the present invention, since the designating means designates the transmission power using the table in which the range of the received signal level and the transmission power are associated with each other, the transmission power is designated by a simple configuration. can do. The present invention
The base station device of the
Received signal of control wave of other device in lot
Signal level range and received signal level range
And the transmit power of the control channel
A table that corresponds to the higher the transmission output
A plurality of storage units for each installation environment;
Environment of the own device among the plurality of tables stored in the means
Using a selection means for selecting one of the tables, the selection <br/>-option tables according to, measurement by the measuring means
The control signal that the device should output according to the received signal level.
Specifying means for specifying the transmission output of the channel, and the transmission type
In the mobile slot, the transmission specified by the specifying means is performed.
Transmission means for transmitting the control channel transmission wave
May be provided .

With such a configuration, the base station apparatus of the present invention uses only a plurality of tables having different correspondences between the reception signal level range and the transmission output depending on the installation environment. In addition to changing the transmission output accordingly, there is an effect that the transmission output can be changed more efficiently according to the installation environment. Further, the selection means includes an environment determination means for determining the installation environment according to the reception status of the control channel from the peripheral base station device,
A table may be selected using the judgment result of the environment judging means.

With such a configuration, in the base station apparatus of the present invention, the environment determining means determines the installation environment and determines the transmission output using the table according to the determination result. If the transmission output of the control channel is changed based on the determination of the installation environment and the measurement of the received signal level on a regular basis, such as once, it is possible to maintain an interference area without the need for manual operation. There is.

Further, the measuring means is a control chip of its own device.
In addition to the channel transmission time slots , each transmission time slot that can be assigned as the control channel of the own device
Takes measures the reception signal level of the transmission wave of the control channel of another system, the environment judgment unit includes a counting means for counting the number of past the predetermined level of the received signal level measured by the measuring means, the counting The installation environment may be determined according to the number counted by the means.

With such a configuration, the base station apparatus of the present invention counts the number of received signal levels of the control channels of other apparatuses exceeding a predetermined level, so that the base station apparatus can detect the large number of the neighboring base stations. It can be regarded as a large number (high density), and the installation environment can be determined according to this degree. The base station device further includes demodulation means for demodulating a transmission wave of a control channel of another device for all transmittable transmission time slots of the control channel of the own device, and the environment determination means performs each transmission by the demodulation means. The determination means for determining whether or not the time slot is normally demodulated, and the counting means for counting the number of times normally determined by the determination means are provided, and installed according to the number counted by the counting means. It may be configured to determine the environment.

With this configuration, the base station apparatus of the present invention counts the number of normally demodulated transmission waves of the control channel of the other apparatus, thereby determining the large number of the transmission waves of the peripheral base stations. It can be regarded as a large number (high density), and the installation environment can be determined according to this degree.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a base station device of a first embodiment.

FIG. 2 is a diagram showing stored contents of a transmission output table 152a.

FIG. 3 is a block diagram showing a configuration of a base station device of a second embodiment.

FIG. 4 is a diagram showing stored contents of transmission output tables 162a, b, c.

FIG. 5A is a diagram showing a regular arrangement of base station devices in the case of efficiently covering a wider area with a small number of base stations. (B) is a figure which shows the example of arrangement | positioning of the present base station apparatus. (C) is a diagram showing an interference area due to overlapping of wireless zones.

FIG. 6 is a diagram showing an arrangement example of transmission slots of a control channel according to the TDMA / TDD system.

[Explanation of symbols]

10 antennas 11 Send / receive switch 12 Transmitter 13 Receiver 14 line section 15 Control unit 151 transmission slot selection unit 152 Transmission output determination unit 152a transmission output table 153 Transmission output control unit

Claims (4)

(57) [Claims] 1. A transmission time slot of a control channel of its own device.
Signal of the transmitted wave of the control channel of another device
It receives the measuring means for measuring the level, the range of the received signal level and the transmission output of the control channel.
The higher the signal level range, the smaller the transmission output.
Multiple tables are stored for each installation environment.
Of the storage means and the plurality of tables stored in the storage means,
Means for selecting one table according to the storage environment
When using the selection tables, by the measuring means
It should output according to the measured received signal level
Designating means for designating the transmission output of the control channel, and by the designating means in the transmission time slot
Transmit the control channel transmit wave with the specified transmit power.
Group Chikyoku device you anda transmitting means that. 2. The selecting means comprises an environment judging means for judging an installation environment according to a reception condition of a control channel from a peripheral base station device, and selects a table by using a judgment result of the environment judging means. The base station device according to claim 1. 3. The measuring means is a control channel of its own device.
In addition to the transmission time slot, the reception signal level of the transmission wave of the control channel of the other device in each transmission time slot that can be assigned as the control channel of the own device is measured, and the environment determination unit is measured by the measurement unit. 3. The base station apparatus according to claim 2, further comprising a counting unit that counts the number of received signal levels exceeding a predetermined level, and determines the installation environment according to the number counted by the counting unit. 4. The base station apparatus further comprises demodulation means for demodulating a transmission wave of a control channel of another apparatus for all transmittable transmission time slots of a control channel of the own apparatus, and the environment determination means includes: The demodulating means is provided with a judging means for judging whether or not each transmission time slot is normally demodulated, and a counting means for counting the number of times normally judged by the judging means, and is counted by the counting means. The base station device according to claim 2, wherein the installation environment is determined according to the number.