Multi-address communication method and system thereof, and base station equipment thereof and mobile station

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention is a broadcast communication system and a broadcast in a mobile communication system that controls the transmission power of a mobile station and the transmission power of a base station when a broadcast message is transmitted from a base station to a plurality of specific mobile stations by a broadcast channel. Communication methods and base station equipment and mobile stations.

【0002】

[Conventional technology]

Conventionally, there are various methods for optimizing mutual transmission power between a base station and a plurality of mobile stations in a mobile communication system. In particular, in the DS-CDMA system that can transmit and receive multiple channels in the same frequency band, it is often adjacent to multiple cells, avoiding the influence of interference with other cells, and the base station and mobile station of the own cell. In order to stabilize transmission and reception with, not only the transmission power of the base station to the mobile station but also the transmission power of the mobile station to the base station is strongly required to be optimized.

【0003】

For example, Japanese Patent Application Laid-Open No. 7-336292 describes a step of calculating a signal path gain between a transmitting device and a corresponding receiving station in order to maintain sufficient transmission quality on a communication link, and a common step among receiving stations. The steps for measuring the communication path interference power level, the inverse of the signal path gain, the common communication path interference power level, and the minimum target value of the ratio of the received carrier power to the common communication path interference power are determined in advance. Between each continuous power adjustment execution of a cycle of calculating the product of values, adjusting the power of the signal transmitted by the transmitter according to the value of the product, and adjusting the power of the signal. It is described that by repeating each of the above steps by changing the time interval between them, the necessity of simultaneousness and cooperation between a plurality of transmitting devices is alleviated, and the cost of transmitting power control is suppressed. ..

【0004】

Further, regarding the transmission power control method in the spread spectrum communication device, Japanese Patent Application Laid-Open No. 8-32513 uses transmission power control bits sequentially transmitted from a receiving station to a transmitting station, and continuously having the same value of the transmission power control bits. A step of storing a predetermined transmission power control amount at the transmitting station according to the number of receptions, a step of sequentially transmitting the transmission power control bit from the receiving station to the transmitting station, and a step of sequentially transmitting the transmitting power control bit from the receiving station to the transmitting station. According to the step of detecting the number of consecutive receptions of the same value of the transmitted power control bit and the transmission power control amount corresponding to the number of consecutive receptions of the same value of the transmission power control bit at the transmitting station. When the step of controlling the transmission power is provided and the transmission power control bits of the same value are continuously received, it is considered that the reception power of the partner station fluctuates significantly, and the transmission power is transmitted as the continuous reception time elapses. It is described that the increase / decrease amount of is increased to follow sudden fluctuations in the communication path.

【0005】

Further, regarding mobile communication in which communication is performed by code division multiplexing (CDMA) wireless signals or mobile communication systems and the radio wave propagation status changes in a short time, Japanese Patent Application Laid-Open No. 9-275373 (Patent No. 2803626) and Japanese Patent Application Laid-Open No. It is described in Japanese Patent Application Laid-Open No. 10-224293. In both publications, in a mobile station transmission power control method that changes the transmission power of its own station by a preset fixed amount, when an instruction to increase or decrease the transmission power is received from the radio base station control device, the output increase / decrease range It is described that the transmission output control means of the mobile station is instructed to increase or decrease the amount set by the setting means.

【0006】

Here, normally, in a cellular mobile communication system, as channels transmitted from a base station, individual channels assigned to each user (mobile station) and capable of making a call, and mainly control information and the like are transmitted, and all users transmit. A common channel that receives and uses control information is defined. However, although a broadcasting channel that can be arbitrarily received by a plurality of unspecified majority is defined, a broadcasting channel that can be received and used by a plurality of specific users at the same time is neither standardized nor defined. Therefore, in the cellular mobile communication system, in order to provide the broadcast service, the same information is sent to each target user separately, or simultaneous communication is performed using a common channel common to each target user. It is conceivable to do either.

【0007】

On the other hand, in the 3rd generation and later mobile communication systems, which are currently being standardized, it is considered that services by such a broadcast channel will be provided. Here, in particular, assuming a cellular system based on the CDMA system based on the spread spectrum system, it is important to minimize the interference with other channels due to the transmission of the broadcast message. That is, it is desirable that the reception power of the broadcast message of the mobile station is the minimum necessary for the user having the worst reception condition among the specific users to receive.

【0008】

[Problems to be Solved by the Invention]

Regarding such a broadcast message, Japanese Patent Application No. 10-310048, which is currently pending, states that transmission power control in a broadcast communication system in which a plurality of specific mobile stations receive a broadcast message transmitted by a base station through one communication channel. The method is described. In the same publication, the mobile station includes a receiving unit that receives the broadcast message, a determination device that measures the received power of the broadcast message to determine whether the received power is sufficient, and a broadcast message to the base station. A transmission power increase request signal transmitter that requests an increase in transmission power, a switch that turns on transmission of the transmission power increase request signal when the reception power of the broadcast message is insufficient, and a transmission power of the transmission power increase request signal. The controller has a controller that gradually increases the transmission power of the transmission power increase request signal when the reception power of the broadcast message decreases even after the transmission power increase request signal is transmitted. Raise to.

【0009】

Further, the base station includes a transmission unit for the broadcast message, a controller for controlling the transmission power of the broadcast message transmitter, and a reception unit for receiving the transmission power increase request signal transmitted by the mobile station. The controller increases the transmission power when it receives the transmission power increase request signal, and gradually lowers the transmission power when it does not receive the transmission power increase request signal for a certain period of time. These controls allow the poorest reception mobile station to transmit the broadcast message with the minimum power to receive the broadcast message with sufficient quality.

【0010】

However, the publication does not mention that the base station instructs the mobile station to control the transmission power of the mobile station. If this transmission power control is not performed, the mobile station does not reduce the transmission power, so that the merit of sharing the transmission channel cannot be utilized. Conversely, if the transmission power of the mobile station is controlled, the transmission power of the transmission power increase request signal from the mobile station can be shared by all the mobile stations that receive the broadcast message. This leads to a reduction in power consumption.

【0011】

However, when the transmission power control from the base station is performed by the method described in the above-mentioned publication, the mobile station whose reception power of the broadcast message reaches a sufficient value turns off the transmission of the transmission power increase request signal. Therefore, in the base station, the received power of the transmission power increase request signal from the mobile station decreases sharply, and even though there is a mobile station that cannot receive the broadcast message with sufficient quality, the same from the base station. The transmission power of the information message may not be increased or decreased for a while, and as a result, the time for transmitting the transmission power increase request signal from the mobile station becomes longer, and the power consumption of the mobile station increases. There was a case.

【0012】

In consideration of the above conditions, the present invention makes the quality sufficient in a short time at the start of receiving the broadcast service when transmitting the broadcast message from the base station to a plurality of specific mobile stations, and moves the broadcast message. This is to reduce the power consumption by controlling the transmission power of the station.

【0013】

[Means for solving problems]

INDUSTRIAL APPLICABILITY In a broadcast communication system in which a plurality of mobile stations receive a broadcast message transmitted by a base station via a broadcast channel, the base station uses the received power of the broadcast message in the plurality of mobile stations. A receiving unit that receives a transmission power increase request signal from the mobile station that is transmitted correspondingly, and a received power detection that detects the received power of the transmission power increase request signal from the mobile station received by the receiving unit. A unit, a transmission power control generation means that determines and generates a transmission power increase or decrease request signal for the mobile station by the received power, and a transmission power to each mobile station by the transmission power increase request signal from the mobile station. A power control unit for controlling is provided, and the transmission power increase or decrease request signal is transmitted to the mobile station together with the broadcast message, and the mobile station transmits the transmission power increase or decrease request signal and the broadcast message. It is characterized in that the transmission power of the transmission power increase request signal from the mobile station is gradually reduced according to the received power.

【0014】

Further, the present invention is a broadcast communication method in which a plurality of mobile stations receive a broadcast message transmitted by a base station through a broadcast channel, wherein the base station receives power of the broadcast message at the mobile station. The transmission power increase request signal from the mobile station to be transmitted is received, the received power of the received transmission power increase request signal is detected, and the transmission power increase or decrease request signal is determined and generated by the received power. , The transmission power to the mobile station is controlled by the received power, and the transmission power increase or decrease request signal is transmitted to the mobile station together with the broadcast message, and the mobile station transmits the transmission power increase or decrease request signal. Is received, and the transmission power of the transmission power increase request signal from the mobile station is gradually reduced according to the reception power of the broadcast message.

【0015】

Further, the present invention is a base station that transmits a broadcast message to a plurality of mobile stations by a broadcast channel, and is transmitted to the base station according to the reception quality of the broadcast message at the plurality of mobile stations. A receiving unit that receives a transmission power increase request signal, a detection unit that detects the received power of the transmission power increase request signal detected by the receiving unit, and a transmission power increase or decrease request signal to the mobile station by the received power. The transmission power increase or decrease request signal generating means for determining and generating the transmission power, and the power control unit for controlling the transmission power to the mobile station by the received power are provided, and the transmission power increase or decrease request signal is provided together with the broadcast message. Instructs the increase or decrease of the transmission power of the mobile station, and the mobile station gradually lowers the transmission power of the transmission power increase request signal according to the reception power of the transmission power increase or decrease request signal and the previous broadcast message. It is characterized by that.

【0016】

Further, the present invention comprises a mobile station that receives a broadcast message through a broadcast channel transmitted from a base station, a receiving unit that receives a transmission power increase or decrease request signal from the base station together with the broadcast message, and the above. When the received power that detects the received power of the broadcast message from the receiving unit is compared with the received power and a predetermined threshold value and the received power is large, a request for increasing the transmission power to the base station is made. When the transmission of the signal is stopped and the received power is small and the transmission power increase request signal is received, the transmission of the transmission power increase request signal is provided with a power control unit for increasing the transmission power of the transmission power increase request signal. It is characterized in that the transmission power of the transmission power increase request signal is gradually reduced when the operation is stopped.

【0017】

Further, in the mobile communication system according to the present invention, in a broadcast communication system in which a plurality of mobile stations receive a broadcast message transmitted by a certain channel of a base station, the optimum value of the received power of the broadcast message at the mobile station. It realizes high-speed convergence to the mobile station and reduction of power consumption of the mobile station by sending a transmission power control signal.

【0018】

Further, according to the present invention, the mobile station uses the power measuring device 24 to receive the broadcast power, and the transmission power control signal detector 25 uses the transmission power control signal detector 25 to transmit the transmission power control signal from the base station. Detect each. In response to this result, the transmission power controller 26 determines the power of the transmission power increase request signal for the base station. At this time, if the received power of the broadcast message is equal to or higher than a certain threshold, the transmission power increase request signal may not be sent (the power is set to 0 in the transmission power controller 26), but this signal is in the cell. Considering that all mobile stations in the above are transmitting using a common channel, even if the received power exceeds the threshold, the transmission power is not suddenly set to 0, but the power is reduced step by step to broadcast the message. It is possible to quickly converge the received power of the mobile station to the optimum value, and as a result, reduce the power consumption of the mobile station.

【0019】

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment according to the present invention will be described in detail with reference to the drawings.

【0020】

[First Embodiment] (1) Explanation of configuration FIG. 1 shows the configuration of a base station (a) and a mobile station (b) of a broadcast communication system of a broadcast message as an embodiment of the present invention.

【0021】

In FIG. 1A, the base station transmits the broadcast message with a modulator 12 that modulates the broadcast message with QPSK, QAM, or the like, a circulator 11 that separates the transmitted wave and the received wave, and a plurality of broadcast messages. An antenna 10 that receives a transmission power increase request signal from a mobile station, a demodulator 13 that demodulates a transmission power increase request signal from a plurality of mobile stations, and a receive power of a transmission power increase request signal from a plurality of mobile stations. The power detection unit 14 to detect, the power control unit 16 that controls the transmission power from the base station to the mobile station by the received power, and the TPC (Transmitter Power) that generates the transmission power control signal bit that controls the transmission power of the mobile station. Control) It is composed of a signal generator 17 and a timer 15 that counts the time when the received power of the transmission power increase request signal from the mobile station falls below a certain threshold.

【0022】

However, although the configuration relating to the broadcast channel for transmitting the broadcast message has been mainly described, it goes without saying that the configuration relating to the transmission and reception of the individual channel and the common channel is also provided.

【0023】

Further, in FIG. 1B, the mobile station uses a modulator 22 that modulates the transmission power increase request signal to the base station, a circulator 21 that separates the transmission wave and the reception wave, and the transmission power increase request signal. An antenna 20 that transmits and receives a broadcast message from the base station, a demodulator 23 that demodulates the broadcast message from the base station, and a power detector 24 that detects the received power of the broadcast message from the base station. It is composed of a TPC bit detector 25 that detects a transmission power control (TPC) signal bit from a base station, and a power control unit 26 that controls a transmission power according to the received power and the TPC bit.

【0024】

In addition, in this mobile station, the configuration related to the transmission of the broadcast channel for receiving the broadcast message and the transmission power increase request signal of the base station has been mainly described, but the configuration related to the transmission and reception of individual channels and common channels in the mobile station is also possible. Of course, it has.

【0025】

Here, if the broadcast communication system adopts the CDMA system, the base station and the plurality of mobile stations have the same spreading code determined in advance, and the base station spreads using this spreading code, and a plurality of them are spread. The broadcast message from the base station can be received by multiple specific mobile stations at the same time by back-spreading at the specific mobile station.

【0026】

Table 1 shows the signals exchanged between the base station and a plurality of mobile stations in the broadcast communication system.

【0027】

[table 1]

<img file="JP2001007759A_D0001.tif" />Further, FIG. 2 is a configuration diagram showing an example of the demodulator 13 of the base station. Received signals Rx such as transmission power increase request signals transmitted from a plurality of mobile stations are selected as a plurality of received signals by the input selection circuit 41 and input to the lake finger receiving unit 42. At the same time, it is input to the path search circuit 43, and the multipath delay profile is estimated. The multiplier 44 generates a spreading code by multiplying a long code assigned to each mobile station and a short code assigned to each channel. In each of the lake finger circuits # 1 to # 8, the spreading code is delayed by the delay circuit 422 according to the delay profile, and the signal sent from the input selection circuit 41 is despread by the despreading circuit 421. Of the despreaded signals, the pilot symbol is input to the transmission line estimation circuit 423 to estimate the transmission line characteristics. Synchronous detection is performed by the synchronous detection circuit 424 using this coefficient of determination. In each of the lake finger circuits # 1 to # 8, the synchronous detection circuit 424 outputs the output, and the synchronous detection output is combined by the maximum ratio synthesis circuit 45.

【0028】

Note that FIG. 2 is merely an example, and the demodulator of the base station described in the present invention is not limited to the configuration shown in FIG.

【0029】

Next, as shown in FIG. 1A, the base station modulates the broadcast message with the modulator 12 and transmits it from the antenna 10 via the circulator 11. The signal from the mobile station is demodulated by the demodulator 13 via the antenna 10 and the circulator 11, and the received power of the transmission power increase request signal from the mobile station is detected by the power detection unit 14. As a method for measuring the received power, it is conceivable to use the average of the received powers of a specific number of symbols. The transmission power control unit 16 controls the transmission power as follows according to the signals from the power detection unit 14 and the timer 15.

【0030】

(1) When the received power of the base station of the transmission power increase request signal from a plurality of mobile stations exceeds the second threshold value (B in FIG. 4 described later), the broadcast message transmission power of the base station is increased. ..

【0031】

(2) Increase in transmission power from multiple mobile stations If the reception power of the request signal at the base station continues for a certain period of time below the second threshold value, the broadcast message transmission power of the base station is reduced.

【0032】

(3) In cases other than (1) and (2) above, the broadcast message transmission power of the base station is not changed.

【0033】

In the transmission power control (TPC) signal generator 17, the received power of the transmission power increase request signal from the plurality of mobile stations at the base station is the first threshold value (the second threshold value B set by the transmission power controller 16). Value different from: If it exceeds A) in Fig. 4, which will be described later, the transmission power reduction request signal, which is a request signal to reduce the transmission power of each mobile station, is received if the reception power is equal to or less than the first threshold value. A transmission power increase request signal, which is a request signal for increasing the transmission power of each mobile station, is generated and sent to the modulator 12, and the transmission power increase or decrease request signal is modulated together with the broadcast message and transmitted to the mobile station.

【0034】

Of the signals sent from the base station to the mobile station, the transmission power increase or decrease request signal is always transmitted at a constant level (a level that reaches the mobile station at the end of the cell with sufficient quality).

【0035】

On the other hand, in the mobile station, the signal from the base station is demodulated by the demodulator 23 via the antenna 20 and the circulator 21, and receives the broadcast message and the transmission power increase or decrease request signal. Further, the power detection unit 24 detects the received power of the broadcast message, and the transmission power control (TPC) signal detector 25 detects the transmission power increase or decrease request signal from the base station.

【0036】

Based on these two detection results, the transmission power controller 26 of the mobile station controls the transmission power of the transmission power increase request signal to the base station as follows.

【0037】

(1) The received power of the broadcast message from the base station is below the fourth threshold value (the level at which the broadcast message can be received with sufficient quality), and the transmission power control signal from the base station is the increase request signal. If so, increase the transmission power.

【0038】

(2) If the received power of the broadcast message from the base station is equal to or less than the fourth threshold value and the transmission power control signal from the base station is a reduction request signal, the transmission power is reduced.

【0039】

(3) If the received power of the broadcast message from the base station is larger than the fourth threshold value, the transmitted power is gradually reduced. In this case, the instruction by the transmission power increase or decrease request signal from the base station is ignored. Further, the method of reducing the transmission power in this case is not always the same as in the case of (2).

【0040】

The transmission power increase request signal from the mobile station is modulated by the modulator 22 and transmitted to the base station via the circulator 21 and the antenna 20.

【0041】

The above base station and mobile station have shown a configuration in which the antennas 10 and 20 are directly driven from the modulators 12 and 22 via the circulators 11 and 21, but the modulators 12 and 22 are used in the case of the CDMA system. Spread-modulates the transmission power increase request signal with a PN signal, converts it into a predetermined high-frequency signal, amplifies the power in the power amplification stage, and then supplies the signal to the antennas 10 and 20. Further, although an example in which the signal is directly input from the circulator 11 to the demodulator 13 is shown, the demodulator 13 converts the high frequency signal received from the mobile station into an intermediate frequency and then back-diffuses the PN signal. The baseband signal is converted into a baseband signal, and the baseband signal, which is a transmission power increase request signal from the mobile station, is input to the power measuring device 14 to detect the received power. Further, although an example in which the signal is directly input from the circulator 21 to the demodulator 23 is shown, the demodulator 23 is based by converting the received high frequency signal into an intermediate frequency and then back-spreading it by the above PN signal. It is converted into a band signal, a broadcast message and a transmission power control signal from the base station are output, and the baseband signal is input to the power detection unit 24 to detect the received power.

【0042】

The communication method of the mobile communication system is not particularly limited, but IMT-2000, cdmaOne, and TDMA (Time Division) that use the CDMA (Code Division Multiple Access) method that enables broadcast messages easily. The present invention can also be applied to PDC (Personal Digital Cellular) and PHS (Personal Handyphone System) that use the Multiple Access) method.

【0043】

(2) Explanation of operation FIG. 3 is an example of the state of the broadcast communication system assumed in the present invention. The base station 30 having the device shown in FIG. 1 (a) and the mobile stations 31 to 35 having the device shown in FIG. 1 (b) can communicate with each other in one cell 38 shown by the alternate long and short dash line, and the base. The broadcast message is transmitted from the station 30 using the broadcast channel. The area 36 shown by the dotted line is a good quality area where the broadcast message can be received with sufficient quality at a certain point in time, and the range expansion area 37 shown by the solid line increases the transmission power of the base station by one step from the time point of the area 36. It is an extended good quality area of time. Also, 38 represents the cell boundaries covered by base station 30, and region 37 is always inside 38. A cell that can be communicated by another base station is adjacent to the outside of the cell 38. When the transmission power to the mobile station of the base station is increased by the transmission power increase request signal from the mobile station and the range area 36 in which the broadcast message is received with sufficient quality is expanded to the area 37, the mobile stations 33 and 34 are newly added. Is in that range. By expanding this area, the mobile stations 33 and 34 do not need to send the transmission power increase request signal that has been transmitted so far, and can stop the transmission. However, according to the method according to the present invention, the mobile stations 33 and 34 and 34 does not suddenly reduce the transmission power of this transmission power increase request signal to 0, but gradually decreases it. Further, since the reception quality of the mobile station 35 is not sufficient even at this point, the mobile station 35 continues to send the transmission power increase request signal to the base station. The base station further increases the transmission power in response to the request by the transmission power increase request signal. By repeating the above operation, the transmission power (downlink) of the base station to the mobile station until the reception power of all the mobile stations reaches a sufficient level, and the reception power of the transmission power increase request signal from each mobile station (downlink). An example of the transition of uplink) is the case where the method according to the present invention is applied (Fig. 4 (b)) and the case where the operation can be inferred from the above-mentioned explanation of Japanese Patent Application No. 10-310048 (Fig. 4 (a)). Will be described.

【0044】

In FIG. 4, the horizontal axis is the time axis and the vertical axis is the transmission / reception power. The uplink from the mobile station to the base station shows the reception power of the transmission power increase request signal received by the base station, and the downlink from the base station to the mobile station shows the transition of the transmission power of the broadcast message transmitted by the base station. Each is represented. In the figure, the three dotted lines A, B, and C are the lines showing the following numerical values. (A) The first threshold value used when determining whether the transmission power control signal sent by the base station to the mobile station is an increase request or a decrease request. (B) A second threshold used by the base station to determine whether to increase the transmission power of the broadcast message. (C) A third threshold of power that allows the poorest reception mobile station in the cell to receive broadcast messages of sufficient quality. That is, the optimum transmission power value of the base station at that time.

【0045】

Normally, A&gt; B, but it should be noted that the magnitude relationship and spacing of each line other than that have no meaning.

【0046】

First, FIG. 4 (a) by the conventional method will be described. In FIG. 4 (a), since the received power of the transmission power increase request signal from the mobile station does not reach the second threshold value B at time 0 (a line), the base station transmits the signal to the mobile station as a downlink. A power increase request signal is sent, and the received power of the base station increases. At time 1, the received power of the transmission power increase request signal from the mobile station exceeds the second threshold value B (line b), and the transmission power of the broadcast message to the mobile station of the base station begins to increase (b'. line). At time 2, the received power from the base station of a mobile station among multiple mobile stations is at a sufficient level, and the mobile station requests the transmission power increase because the base station does not need to increase the transmission power. Stop transmitting the signal (c line). That is, the transmission power of the transmission power increase request signal by the mobile station is set to 0. Therefore, the received power of the transmission power increase request signal received by the base station at time 2 is reduced by that amount because the transmission power of one mobile station becomes 0.

【0047】

In the broadcast communication system, the transmission power increase request signal from each mobile station uses a common channel for all mobile stations in the cell, so that the reception power of the transmission power increase request signal decreases at this time 2. .. Normally, this decrease is considered to be larger than the interval between the first threshold A and the second threshold B, so the increase in the transmission power of the broadcast message from the base station stops (d line), and the base station The received power of is not changed until the time 3 when the second threshold value B is exceeded next. In addition, each mobile station gradually increases the transmission power of the transmission power increase request signal to the base station according to the transmission power increase request signal from the base station (e-line).

【0048】

Furthermore, when the received power of multiple mobile stations reaches a sufficient level at the same time (point E), the received power of the transmission power increase request signal from the mobile station of the base station is significantly reduced as at time 4 (f line). ). In such a case, the base station sends a transmission power increase request signal from the mobile station to the mobile station to increase the transmission power of the mobile station (g line). It takes time for the received power of the base station to reach the second threshold value B again. Since the transmission power increase request signal from the mobile station is equal to or less than the second threshold value B, the base station must keep the downlink transmission power constant (h line) and receive the transmission power increase request signal for a certain period of time. For example, since the transmission power is gradually reduced (i-line), the transmission power of the base station decreases from time 5 to time 6 even though there are mobile stations whose received power is not yet sufficient.

【0049】

After this time 6, the base station gradually increases the transmission power of the broadcast message to the mobile station as a downlink as shown in FIG. 4 (a) in response to the transmission power increase request signal from the mobile station. (j line). In addition, the base station sends a transmission power increase request signal to the mobile station to output a request signal to increase the transmission power of the mobile station, and increases the transmission output of the transmission power increase request signal to the mobile station base station. Then, as shown in the uplink in FIG. 4 (a), the detection level of the received power of the transmission power increase request signal from the mobile station in the base station is gradually increased (k line). Therefore, the base station increases the received power of the transmission power increase request signal from the mobile station.

【0050】

As a result, the received power of all mobile stations reaches a sufficient level, and the transmission of the transmission power increase request signal from all mobile stations is stopped at time 7 (l line). After time 7, each mobile station can obtain a high quality received signal, so there is no need to transmit a transmission power increase request signal to the base station, and the received power of the base station remains 0, downlink. Holds the transmit power for a certain period of time.

【0051】

On the other hand, when the method according to the present invention is applied in the same situation, it becomes as shown in FIG. 4 (b). From time 0'to 2', the transition is the same as in Fig. 4 (a) (lines a and b), but the mobile station whose received power reaches a sufficient level at time 2'is a transmission power increase request signal. The transmission power of is not suddenly set to 0, but is lowered step by step (m line). As a result, since the other mobile stations are gradually increasing the transmission power of the transmission power increase request signal to the base station, the reception power of the base station starts to increase again before becoming lower than the second threshold value B. (n line), the time 4'when the reception power of the next two or more mobile stations becomes sufficient is earlier than the time 4 in FIG. 4 (a). On the other hand, the transmission power from the downlink base station to the mobile station gradually increases because the reception power of the transmission power increase request signal to the base station does not fall below the second threshold value B (o line).

【0052】

Furthermore, after time 4', these two or more mobile stations also gradually reduce the transmission power of the transmission power increase request signal to the base station (p line), so that the reception power of the base station is shown in FIG. 4 (a). The section from time 4 to 6 when is equal to or less than the second threshold value B is shortened to time 4 ~ 6' in FIG. 4 (b), and the transmission power of the base station is reduced as shown in FIG. 4 (a). The phenomenon is also avoided. In addition, the transmission power of the broadcast message from the downlink base station to the mobile station is that the reception power of the transmission power increase request signal to the base station is equal to or less than the second threshold value B after time 4 . Therefore, it is held at a constant level (q line). In addition, the received power of the transmission power increase request signal from the mobile station of the base station is gradually increasing from the mobile station that cannot receive sufficient quality, and the transmission power of the transmission power increase request signal is gradually increased until time 7'. The balance point between the mobile station that gradually reduces the transmission power of the transmission power increase request signal and the mobile station that gradually increases becomes the intersection of the p line and the r line.

【0053】

After that, the time when the received power of all the mobile stations becomes sufficient is time 7', which converges in a shorter time than the time 7 in FIG. 4 (a). In addition, after the time 8'when the transmission power of all mobile stations becomes 0, each mobile station can obtain a broadcast message as a high-quality reception signal, so that each mobile station can obtain a transmission power increase request signal. Does not need to be transmitted to the base station, and the received power of the base station remains 0 (u line). In addition, when the transmission power of the transmission power increase request signal to the base station of the mobile station decreases (s line) and becomes equal to or less than the second threshold value B, the downlink transmission power of the broadcast message or the like is held (t). (Line), the downlink transmission power will stop increasing and reach a certain level, and then it will decrease after a predetermined time because there is no transmission power increase request signal to the base station of the mobile station (v line). ).

【0054】

In both cases of Fig. 4 (a) and Fig. 4 (b), shadowing when any mobile station moves behind the building after time 7 or time 7', and fading phenomenon in which the reception level drops sharply. When the above occurs, the reception quality at the mobile station deteriorates, so that the transmission power increase request signal is transmitted again to the base station, and the above operation is restarted.

【0055】

The example shown in FIG. 4 will be described in more detail as shown in FIG. In FIG. 5, for example, with the mobile stations as the four stations (a)-(d), FIG. 5 (a) by the conventional method is shown in FIG. 4 (a), and FIG. 5 (b) by the method of the present invention is shown in FIG. 4 ( It corresponds to b).

【0056】

In Fig. 5 (a), at time 0 when the broadcast message was started to be transmitted from the base station, the four mobile stations (a), (b), (c), and (d) had low power and transmitted power increase request signals. To the base station (a line). At time 1, each of the four mobile stations transmits a transmission power increase request signal to the base station with a power higher than that of time 0 (line b). At time 2, since the fourth mobile station d has obtained sufficient received power, the transmission of the transmission power increase request signal to the base station is stopped (c line), and the received power of the base station is set to time 1. Compared to that, it has decreased significantly. Next, until time 3-4, the mobile stations (a)-(c) increase the transmission power increase request signal to their own base stations (e-line). Then, at time 4, the mobile stations (b) and (c) have obtained sufficient received power, so the transmission of the transmission power increase request signal to each base station is stopped and set to 0 (f line). ).

【0057】

At time 5, only the mobile station (a) increases the transmission power increase request signal to the base station (g line). Furthermore, until time 6, only the mobile station (a) increases the transmission power increase request signal to the base station (k line). After that, at time 7, the mobile station (a) also obtained sufficient received power, and therefore stopped transmitting the transmission power increase request signal to the base station (l line). In this state, all four mobile stations are receiving broadcast messages from the base station with good quality.

【0058】

On the other hand, FIG. 5B shows a relationship diagram with time regarding the received power of the base station in the transmission power control according to the present invention.

【0059】

Time 0'and time 1'are the same as time 0 and time 1 in FIG. 5 (a) (lines a and b). At time 2', the mobile station (d) reached a level where it could receive the broadcast message of the base station with sufficient quality, but the transmission power for transmitting the transmission power increase request signal to the base station was gradually reduced. (m line), it does not stop suddenly. In addition, at time 3', it is noted that the transmission power of the mobile station (d) is gradually decreasing. At time 4', it is shown that the transmission power of the mobile station d is stopped, and the mobile stations (b) and (c) are also able to receive the broadcast message of the base station with sufficient quality, and the mobile station ( In b) and (c), the transmission power is gradually reduced (p line). This gradual decrease is shown at time 4 "and time 6'. At time 7'and 8', similar to mobile stations (c) and (b) at time 4" and 6'. Since the mobile station (a) can receive the broadcast message from the base station with good quality, the transmission power for transmitting the transmission power increase request signal to the base station is gradually reduced (). s line) is understood. After that, the base station cannot receive the transmission power increase request signal from the mobile station, and it is necessary to transmit the request signal for increasing the transmission power of the base station from the specific mobile station that can receive each broadcast message with high quality. There is no (u line).

【0060】

It should be noted that the times 0 to 7 in FIG. 4 (a), the times 0'to 8', 4 "in FIG. 4 (b), the times 0 to 7 in FIG. 5 (a), and the times in FIG. 5 (b). Although 0'~ 8'corresponds directly, times 0 to 7 in FIG. 4 (a), times 0 to 7 in FIG. 5 (a), and times 0'~ 8', 4 in FIG. 4 (b). "And the time 0'~ 8'in Fig. 5 (b) do not correspond directly.

【0061】

A conceptual sequence diagram of the method according to the present invention described above is shown in FIG. In FIG. 6, as an example, it is assumed that a base station and mobile stations a and b are assumed, and mobile station b is closer to the base station than mobile station a. First, the base station transmits a broadcast message and a transmission power increase request signal as a request signal to the mobile station to a plurality of specific mobile stations a and b. On the other hand, the mobile stations a and b transmit a transmission power increase request signal indicating that the transmission power of the base station is increased. Next, the base station increases the transmission power of the broadcast message or the like of its own station and transmits the broadcast message or the like to the mobile station. Next, since the mobile station b can obtain sufficient reception quality for receiving the broadcast message of the base station, the mobile station a does not send the transmission power increase request signal to the base station, and the mobile station a transmits it to the base station. Sends a power increase request signal.

【0062】

Subsequently, the base station transmits the broadcast message or the like to the mobile station while increasing or maintaining the transmission power. After that, the mobile station a can receive the broadcast message or the like from the base station with sufficient reception quality, and therefore transmits the transmission power increase request signal to the base station while gradually reducing the transmission power. After that, the base station transmits the broadcast message or the like to the mobile station while increasing or holding the transmission power, but since the mobile station does not receive the transmission power increase request signal from the mobile station to the base station, the broadcast message or the like is transmitted. All of the plurality of specific mobile stations that receive the signal are transmitted to each mobile station, recognizing that they are receiving the signal with sufficient reception quality. Further, when the base station does not receive the transmission power increase request signal from the mobile station to the base station for a predetermined time, the transmission power of the broadcast message or the like is reduced and transmitted.

【0063】

In this way, since the transmission output level of the transmission power increase request signal by the mobile station according to the present invention is gradually reduced, each mobile station stabilizes the broadcast message from the time when the base station starts outputting the broadcast message. It is possible to shorten the time until reception, and it becomes possible to send a high-quality broadcast message to a plurality of specific mobile stations.

【0064】

Further, when the output level of the transmission power of the transmission power increase request signal by the mobile station according to the above embodiment is gradually reduced, it is related to the request of the transmission power decrease request signal from the base station, for example, in units of 1 dB. Alternatively, it may decrease at regular intervals such as in 0.5 dB units, or may decrease with a non-linear decrease curve.

【0065】

[Second Embodiment] Next, a second embodiment of the present invention will be described.

【0066】

In the present embodiment, in FIG. 1A, the power detection unit 14 measures the received power of the transmission power increase request signal from a plurality of mobile stations, and the TPC signal generator 17 transmits the transmission power control (TPC) bit signal. When deciding, in addition to the transmission power increase request signal and transmission power decrease request signal of the mobile station, another type of large power increase request signal that requests a large increase in power is prepared, and the received power of the base station is the second threshold. When the value is significantly lower than (B in Fig. 4), this significant power increase request signal is transmitted to the mobile station.

【0067】

The mobile station's TPC bit detector 25 has a function that can detect this third significant power increase request signal in addition to the conventional transmission power increase request signal and transmission power decrease request signal. When the transmission power increase request signal is detected, the transmission power control unit 26 increases the power increase range and transmits the signal. As a result, the period below the second threshold value B (2 to 3 and 4 to 6) is shortened with respect to the sudden decrease in the received power of the base stations at time 2 and time 4 in FIG. 4 (a), and the optimum transmission power is optimized. Fast convergence to values and reduced power consumption of mobile stations are achieved.

【0068】

Further, it is of course possible to combine the first embodiment and the second embodiment, and in this case, a higher effect can be obtained.

【0069】

In the above embodiment, the transmission power control method of the broadcast message by the CDMA method has been described, but the broadcast message is transmitted to all mobile stations existing in the area covered by the base station like a so-called broadcast message. Unlike the case of doing so, when sending a broadcast message such as "All members gather at XX time" to the group members from free time during a group trip, etc., or having multiple sales employees carry a mobile phone. By sending a broadcast message at predetermined time intervals and notifying the performance of all sales employees as a broadcast message, it is possible to aggressively expand sales.

【0070】

Further, the broadcast message may be voice, image data, graph data, or the like, and is not limited to the type of data. Even when a broadcast channel using a spread spectrum modulation system with a time slot such as the TDD-CDMA system is used, the response channel and response slot of each mobile station corresponding to the time slot are set in advance by the system. The present invention can be applied as it is sometimes defined.

【0071】

[Effect of the invention]

According to the present invention, the first effect is the movement in which the received power reaches a sufficient level by the mutual communication control between the base station and a specific plurality of mobile stations when the broadcast message is transmitted by the broadcast channel. By gradually reducing the transmission power of the station, the period during which the reception power of the base station decreases can be shortened, so that the time required for the transmission power of the base station to converge to the optimum value is shortened.

【0072】

The second effect is that the time until the broadcast message can be received with sufficient quality is shortened, so that the time for transmitting the transmission power increase request signal is also reduced, resulting in the consumption of the mobile station. Power can be reduced and battery life can be extended.

[Simple explanation of drawings]

[Figure 1]

It is a block diagram of the base station and the mobile station of the mobile communication system by this invention.

[Figure 2]

This is an example of a block diagram of a demodulation unit of a base station of a mobile communication system according to the present invention.

[Fig. 3]

It is explanatory drawing which shows the location of the base station and the mobile station of the mobile communication system of this invention.

[Fig. 4]

It is a time chart which shows the control of the transmission / reception power in the base station of the mobile communication system of this invention .

[Fig. 5]

It is a time chart which shows the control of the received power in the base station of the mobile communication system of this invention.

[Fig. 6]

It is a sequence between a base station and a mobile station of a mobile communication system according to the present invention.

[Explanation of symbols]

10 base station antenna 11,21 Circulator 12,22 Modulator 13,23 Demodulator 14,24 Power detector 15 timer 16,26 Power controller 17 Transmission power control bit judge 20 Mobile station antenna 21 Transmit power control bit detector 30 base stations 31 ~ 35 Mobile station 36 Good quality reception area 37 Range extension area 38 cell boundaries 41 Input selection circuit 42 Lake finger circuit 421 Reverse diffusion circuit 422 Delay circuit 423 Transmission line estimation circuit 424 Synchronous detection circuit 43 Path search circuit 44 Multiplier 45 Maximum ratio synthesis circuit