JP4962479B2 - Wireless communication device with transmission power control function - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide radio communication equipment provided with a transmission power control function which has a relatively simple structure between mobile radio communication equipment terminals and quickly sets minimum necessary transmission power adaptable to a variety of communication systems. <P>SOLUTION: A connection request signal is transmitted by one of radio communication equipment with high-level transmission electric power. On the reception side, incoming call electric field intensity is compared with a preset threshold and, only when the former is equal to or smaller than the threshold, a connection response signal is returned. On the transmission side, transmission power is reduced when the connection response signal is detected on the transmission side, meanwhile when the connection response signal is not detected, the high level is maintained and a communication mode is entered. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a wireless communication device having a transmission power control function, and more particularly to a wireless communication device having a transmission power control function that can be switched to an appropriate transmission power by a simple process.

  In a mobile communication system, a means for controlling the transmission power to the minimum necessary is extremely important for effectively using a limited channel frequency. In particular, when the same communication system is shared by a large number of wireless communication devices, if some wireless communication devices communicate with large transmission power, communication between other wireless communication devices in the vicinity will be disturbed. Problems arise. Further, communication with more transmission power than necessary also shortens the battery usage time. Therefore, conventionally, various means for controlling the transmission power to the minimum necessary have been taken.

  For example, FIG. 7 is a flowchart showing an overview of the transmission power processing disclosed in Patent Document 1. The wireless communication device of this system includes a function for switching the transmission power between a low level “LOW” and a high level “High”, a function for transmitting a connection request signal, and a connection request signal transmitted from the other party. On the other hand, it has a function of returning a connection response signal. Before starting communication from one of the wireless communication devices having such a function, a connection request signal is transmitted to the communication partner with low level “LOW” transmission power (S101). It is determined whether or not a connection response signal is returned (S102). In this determination, if a connection response signal is detected (S102, Yes), communication is started in a state where the transmission output is set to be kept “LOW” (S103) (S104). On the other hand, if the connection response signal does not arrive from the other party in step S102 (S102, No), the transmission output level is switched to high “High” (S105), and the connection request signal is transmitted again (S106). It is determined whether or not a connection response signal is returned from the wireless communication device (S107). In this determination, if a connection response signal is detected (S107, Yes), communication is started in a state where the transmission output is set to be maintained at “High” (S108). If the connection response signal does not arrive from the other party in process S107 (S107, No), the communication process is terminated and the power is shut off (S109). According to this method, it is possible to avoid unnecessary high-level transmission when communication is possible with low-level transmission power.

  Moreover, FIG. 8 is a figure which shows the outline | summary of the method described in patent document 2. As shown in FIG. The wireless communication device in this example returns a response signal with its own unique ID when receiving a predetermined detection signal, a function for switching between two transmission powers of high (“High”) and low (“LOW”). A memory for storing functions and response signals is provided. In this method, as shown in FIG. 8, first, a detection signal for requesting communication with low-level power (“LOW”) is transmitted from the originating wireless communication device (S110). The wireless communication device that has received this signal returns a response signal with its own unique ID (identification number), and the originating wireless communication device demodulates these response signals and stores them in the storage device ( S111, 200 to 202). Next, the transmission side wireless communication device switches the transmission power to a high level (“High”), similarly transmits a detection signal (S112), and returns a response signal and unique ID information as a list 203 to 205. While storing (S113), based on the list | wrist of the memorize | stored response signal, the communication state between each radio | wireless communication apparatus is judged (S114). In this example, no. 001 to No. The presence / absence of response signals from the three wireless communication devices 003 is stored as a list, and appropriate communication is performed based on the communication availability result for each of the high (“High”) and low (“LOW”) transmission powers. It is possible to determine which is the other party.

Further, in Patent Document 3, as shown in FIG. 9, the base unit 206 detects a signal indicating a reception state of the reception signals (voice signals by voice) from the slave units 207 and 208 and compares it with a preset threshold value. On the basis of the result, there has been proposed one that transmits a signal for controlling transmission power to the handset side.
FIG. 10 is a flowchart showing an example of the control. As shown in FIG. 10 (a), the process of the master unit 206 obtains RSSI (Received Signal Strength) for the received signal from the slave unit (S120). The level is compared with a preset threshold value (S121), and a control signal for increasing / decreasing transmission power according to the magnitude relationship is transmitted to the slave unit (S122). As shown in FIG. 10 (b), the slave unit transmits a signal modulated by voice to the master unit 206 prior to communication (S130), and receives the control signal returned from the master unit as described above. (S131), the transmission power value of the slave unit is set according to the control signal (S132). In other words, a signal (RSSI) indicating the electric field strength of the radio wave transmitted from the slave unit is detected, and if the value is larger than the specified value, the transmission power is reduced. By instructing to increase the power, the transmission power is controlled to be appropriate.
JP-A-8-265252 JP 2004-201156 A Japanese Unexamined Patent Publication No. 7-79484

However, the conventional transmission power control methods described above have the following problems.
In the method described in Patent Document 1, if there is a connection response signal from at least one wireless communication device in response to a connection request signal at a low level, the transmission power is determined to be at a low level, so that it is located far away. There is a high possibility that communication with other wireless communication devices becomes impossible. Therefore, when transmitting information to a plurality of wireless communication devices distributed over a wide range, it is not always an appropriate method.
Further, in the method described in Patent Document 2, since it is necessary to store the information as information even when there is no response from the communication partner, it is a condition that the communication partner is known in advance, and communication with a large number of wireless communication devices is required. In addition, when complicated processing is repeated periodically for establishing a communication path, communication between them becomes impossible, and there is a drawback that increases power consumption.
In the method described in Patent Document 3, in a simultaneous transmission / reception communication system such as a cordless telephone, the transmission power of the own station is increased or decreased based on a power control signal returned from either the slave unit or the master unit during a call. In addition, it is impossible to properly control the transmission power between the slave units by mutual communication. Even if each slave unit has the same function as that of the master unit, the system cannot be realized by the simplex system.
The present invention has been made in view of various circumstances of a wireless communication apparatus having a conventional transmission power control function, and can be employed in various communication systems, and can be quickly implemented with a relatively simple configuration. An object of the present invention is to provide a wireless communication device having a transmission power control function that enables appropriate transmission power control.

  In order to solve such a problem, the present invention provides a wireless communication device including a transmission unit and a reception unit, wherein the reception unit transmits a connection request transmitted from another wireless communication device. A connection request signal detecting means for detecting a signal, a received electric field level detecting means for detecting an electric field strength of a received signal including the connection request signal, and comparing the detected received electric field level value with a preset received electric field level threshold value. If the received electric field level is equal to or lower than the threshold as a result of the comparison by the received electric field level comparing means and the received electric field level comparing means, the connection response signal indicating means for instructing the transmission unit to transmit the connection response signal, and the transmission unit are transmitted. In addition to detecting a connection response signal returned from another wireless communication device in response to the connection request signal, connection response signal detection information is transmitted to the transmission unit. Connection response signal detection means for supplying to the transmission unit, transmission power switching means for switching the transmission power to at least two high and low levels, and transmitting a connection request signal with high transmission power at the start of communication, Transmission power is maintained at a high level when connection response signal detection information is received from the connection response signal detection means of the receiving unit within a predetermined time, and transmission power is received when connection response signal detection information is not received within a predetermined time. Transmission power control means for switching the connection response signal to a low level, and means for transmitting a connection response signal when receiving a connection response signal instruction from the receiving unit.

According to a second aspect of the present invention, in the wireless communication device having the transmission power control function according to the first aspect, the transmission unit includes means for switching the transmission power level in three or more stages, and the connection request signal transmitted at the start of communication is provided. It is characterized by means for transmitting a connection request signal by sequentially switching the transmission power level in a decreasing direction until a connection response signal returned from another wireless communication device is detected in response.
According to a third aspect of the present invention, in the wireless communication apparatus having the transmission power control function according to the first or second aspect, the received electric field level detecting means is an RSSI detecting means or a signal detecting means corresponding to communication quality. It is characterized by being.
According to a fourth aspect of the present invention, there is provided a wireless communication device having the transmission power control function according to any one of the first to third aspects, wherein the wireless communication device has a function of selectively calling one or more specific wireless communication devices. The connection request signal and the connection response signal are exchanged with the wireless communication device that is called automatically.

  The present invention transmits a connection request signal with a high level of transmission power from the transmitting side at the start of communication, etc., and when the receiving side detects this connection request signal, the electric field strength level of the signal or similarly the communication quality Is detected and the connection response signal is returned when the level is equal to or lower than the threshold value. When the connection response signal is returned on the transmission side, the transmission power is maintained at a high level. Then, communication is started. When the connection response signal is not returned, the transmission power level is switched to a low level and the connection request signal is transmitted to detect the presence or absence of the connection response signal. According to this method, for example, the transmission power value that can ensure communication with a radio communication device located farthest in the assumed communication range is set as the maximum transmission power level, and the incoming electric field strength is set as a threshold value. For example, a connection response signal is not returned from a wireless communication device located at a short distance in response to a connection request signal at the maximum transmission power. Therefore, when the communication partner is located only at a short distance, the communication is controlled with low level transmission power. When the communication partner is located far away, the communication partner is controlled with high level transmission power. Thus, communication with the minimum necessary transmission power can be performed quickly without adding the.

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. However, the components, types, combinations, shapes, relative arrangements, and the like described in this embodiment are merely illustrative examples and not intended to limit the scope of the present invention only unless otherwise specified. . In addition, the same parts and the same matters as those already described are denoted by the same reference numerals and numbers, and redundant description is omitted.
FIG. 1 is a block diagram showing a schematic configuration of a wireless communication device having a transmission power control function according to the present invention. The wireless communication device 1 shown in this example includes a transmission unit 2, a reception unit 3, a control unit 4 that performs control described below, and an output signal of the transmission unit 2 in addition to normal control of the wireless communication device. A change-over switch (SW) 6 that transmits a signal that is transmitted to the antenna 5 and that arrives at the antenna 5 to the receiving unit 3, a speaker 7 that converts the demodulated signal output from the receiving unit 3 into sound, and A storage unit 8 and a comparator 9 that function in implementation, and an analog / digital converter (A / D conversion) 10 are provided. In this configuration, the storage unit 8 stores a threshold value for comparison with a received electric field strength (RSSI) value from the communication partner.
Further, the comparator 9 compares the threshold value stored in the storage unit 8 with the value of the received electric field intensity (RSSI) output from the receiving unit 3, and is an analog / digital converter (A / D). Conversion) 10 converts the RSSI signal output from the receiving unit 3 for the comparison into a digital signal and supplies it to the comparator 9.
Note that RSSI (Received Signal Strength) is generally configured to be detected as a DC voltage signal proportional to the received electric field strength, and has a constant electric field strength depending on the power supply voltage of the circuit and the performance of the receiving unit. The above is saturated (see FIG. 4).

Characteristic points in this configuration will be described separately for the transmitter and the receiver as follows. In the following description, “reception unit” and “transmission unit” are not limited to the reception unit 3 and transmission unit 2 shown in FIG. It is described as including functions achieved by cooperation with the block.
First, the receiving unit including the receiving unit 3 includes a connection request signal detecting unit for detecting a connection request signal transmitted from another wireless communication device, and an electric field strength (RSSI) of a received signal from the other party including the connection request signal. The received electric field level detecting means for detecting the received electric field level value is compared with the RSSI threshold value stored in the storage unit 8 as described above, and when the received electric field level is equal to or lower than the threshold value, When the electric field strength is smaller than the threshold value, the transmission unit is instructed to transmit a connection response signal. Prior to the start of communication, when a connection response signal returned from another wireless communication device is detected in response to a request signal transmitted from the transmitting unit 2 of the local station, a connection indicating that there is a connection response The response signal detection information is supplied to the transmission unit or the control unit 4 that controls the transmission unit via the control unit 4.
In addition, the transmission unit transmits a connection request signal with a transmission power switching means for switching transmission power to at least two high and low levels and a high transmission power at the start of communication, and detects a connection response signal of the reception unit within a predetermined time. Transmission power control means for maintaining the transmission power at a high level when receiving connection response signal detection information from the means, and switching the transmission power to a low level when no connection response signal detection information is received within a predetermined time. ing. Furthermore, when a connection request signal transmitted from another wireless communication device at the start of communication is detected (by the receiving unit) and the value is determined to be less than or equal to the threshold value, a connection response signal (supplied from the receiving unit) is When an instruction signal for transmission is received, a connection response signal is transmitted.

  An example of the control processing according to the present invention in such a configuration will be described with reference to FIGS. First, FIG. 2 is a flowchart mainly showing an example of control of the transmission unit of the wireless communication apparatus according to the present invention. First, when a user presses a push-to-talk (PTT) switch (not shown) added to a transmission unit (S1), a connection request signal from the transmission unit 2 is superimposed on a carrier wave, and a transmission / reception switch 6 And transmitted through the antenna 5 (S2). Note that the transmission power at this time is set to a high level. Thereafter, the timer function (not shown) of the control unit 4 starts counting, and the control unit determines whether or not a connection response signal has arrived from another wireless communication device within a predetermined time (S3). . As a result of this determination, if there is a connection response from another wireless communication device (S3, Yes), at least one other wireless communication device can receive with an electric field strength equal to or lower than the threshold level. Therefore, the transmission power is maintained in the high level state (S4), and the mode shifts to the voice transmission mode (S5).

  On the other hand, if no connection response signal is returned from another wireless communication device within the predetermined time in the above-described process S3, none of the other wireless communication devices satisfy the electric field strength condition below the threshold. The transmission power is switched to a low level (“LOW”) (S6), and the voice transmission mode is entered (S5). In other words, if no response of the connection response signal is detected from any other wireless communication device, it can be determined that there is a high possibility that the transmission power is too high to the extent that the incoming field strength exceeds the threshold. If the transmission is continued, the interference to other wireless communication devices occurs, and the power consumption increases more than necessary, so that the transmission power is reduced and the communication mode is shifted.

  FIG. 3 is a flowchart mainly showing an example of control of the receiving unit of the wireless communication apparatus according to the present invention. When the receiving unit 3 is in a standby state, as described above, a connection request signal is transmitted from another wireless communication device at the start of communication. When the signal is received (S10), the signal including the connection request signal is transmitted. The RSSI is detected, and the level is compared with the threshold value stored in the storage unit 8 (S11). If the electric field strength level of this signal exceeds the threshold value (S11, Yes), switching to the voice reception mode without giving an instruction to transmit the connection response signal (S12), but if it is below the threshold value (S11) , No), by supplying an instruction to transmit the connection response signal to the transmission unit 2 or the transmission unit, the transmission unit 2 transmits the connection response signal with the transmission power at a high level (“High”). After that, the voice reception mode is switched (S12).

With this configuration and control, it is possible to prevent transmission with excessive transmission power by only transmitting a connection request signal once and waiting for a connection response signal for a predetermined time. By the way, when the response of the connection response signal is not detected from any other wireless communication device, there is a case where there is no other wireless communication device that can receive the connection request signal. Since it becomes clear in voice communication, it does not become a big trouble. If there is no other wireless communication device that can communicate at all, it is sufficient to move the place and call again. In the above embodiment, for example, when communication with any one of a plurality of fixed stations scattered like a wireless LAN port can be achieved, even when the purpose is achieved, transmission with excessive transmission power is prevented. Useful.
Note that how much the threshold value is set in the present invention is an important factor in operation, and will be described with reference to the drawings. FIG. 4 is a diagram showing an example of the relationship with RSSI expressed as a DC voltage value (V) with the vertical axis representing the RSSI value and the horizontal axis representing the level of the radio wave input to the antenna. Depending on the power supply voltage and the performance of the receiving section, it becomes saturated above a certain electric field strength.
In this figure, it is assumed that when the connection request signal at a high level becomes the input level of the threshold value C, a sufficient call quality is maintained even at a low level of transmission power.
In such a case, when the RSSI is set to a large level like the threshold A and the input level of the connection request signal at the high level is about the threshold A, the input level that is too low even at the low output level. Therefore, if the output is at a high level, the transmission power becomes more than necessary. The higher the threshold value, the more cases where the transmission power becomes higher in the telephone call, and the effect of the invention is less likely to be exhibited.
On the other hand, when the threshold value B is set, if the connection request signal having a high output level reaches an input level that is about the threshold value B, sufficient call quality is not ensured at a low output level. Therefore, it is necessary to set an appropriate value as the threshold value C as the threshold value.

FIG. 5 illustrates the situation described above. Consider a case where a connection request signal (solid arrow in the figure) is transmitted from the wireless communication device 11 in a situation where the portable wireless communication devices 11 to 16 are scattered as shown in FIG. Assuming that the threshold value of the incoming field strength RSSI of radio waves transmitted from the wireless communication device 11 with a high level of transmission power corresponds to the curve 17 indicated by a broken line in terms of distance, a wireless located within that range Since the communication devices 12 to 14 detect the RSSI equal to or higher than the threshold value, the connection response signal is not returned. On the other hand, in the wireless communication devices 15 and 16 located outside the curve 17, the RSSI is equal to or lower than the threshold value, and a connection response signal (broken arrow in the figure) is returned. In the wireless communication device 11 that receives this signal, the connection It operates to detect the response signal and maintain the transmission power at a high level.
That is, if another wireless communication device is located only inside the threshold curve 17, the connection response signal is not returned, and the wireless communication device 11 performs communication by reducing the transmission power to a low level. The influence on other communications can be reduced, and at the same time, power consumption can be reduced.

The present invention can be variously modified without being limited to the embodiments described above.
For example, when the present invention is applied to a wireless communication system having a selective calling function, only the wireless communication device that is the target of selective calling detects the connection request signal and returns the connection response signal described above. Therefore, the number of target wireless communication devices is reduced, and the transmission power required for communication with these devices is controlled, so that the effect of the invention becomes even more remarkable.
In addition, the signal indicating the electric field strength used in the present invention is not limited to RSSI, and any other signal that shows the communication quality of the incoming signal can be used in the same manner. Furthermore, in the case of communication with error correction such as digital modulation, the error rate obtained in the demodulation of error correction on the receiving side can be used as an alternative index.
In addition, the transmission power switching in the present invention need not be limited to high and low, and may be switched to three or more stages.

  FIG. 6 is a flowchart illustrating an example of control in a case where transmission power can be switched between three levels of high level, medium level, and low level. In this example, first, when a user presses a push-to-talk (PTT) switch (not shown) added to a transmission unit, a connection request signal is superimposed on a carrier wave and transmitted from the transmission unit 2. (S20). Note that the transmission power at this time is set to a high level. Thereafter, the timer function (not shown) of the control unit 4 starts counting, and determines whether or not a connection response signal has arrived from another wireless communication device within a certain time (S21). If there is no connection response from another wireless communication device as a result of this determination (S21, No), the transmission power is reduced by one step and set to the medium level (S22), and the connection request signal is transmitted again. Then, similarly to S21, it is determined whether or not a connection response signal has arrived from another wireless communication device within a certain time (S23). If there is no connection response from another wireless communication device as a result of this determination (S23, No), the transmission power is further reduced by one step and set to a low level (S24), and the transmission power is further reduced. Since this is not possible, the voice transmission mode is entered in a low level state (S25).

On the other hand, when a connection response signal is returned from another wireless communication device in the above-described processing S21 and processing S23, there is a wireless communication device with a suitable transmission level at that time. In a state where the transmission power is maintained (S26, S27), a transition is made to the voice transmission mode (S25).
In this way, if transmission power is switched to three or more stages, communication control with minimum necessary transmission power becomes possible. Even in this case, threshold setting and control on the receiving side may be substantially the same as in the case shown in FIG.
In the above-described Patent Documents 1 to 3, means relating to transmission power control are disclosed, and therefore, when implementing the present invention, they can be referred to or used together. Further, if the various control methods related to the wireless communication apparatus of the present invention described above are programmed based on an OS that can be controlled by a computer, the same processing method can be controlled by a computer equipped with the OS. In recent years, a wireless communication device uses a digital processing circuit such as a computer or a DSP. Therefore, if the method of the present invention is stored in a memory as a program or data, the present invention is implemented by partially using those functions. It becomes possible to do.

The block diagram which shows one Example of the radio | wireless communication apparatus of this invention. The flowchart which shows the example of control of the transmission side of the radio | wireless communication apparatus of this invention. The flowchart which shows the example of control of the receiving side of the radio | wireless communication apparatus of this invention. The RSSI characteristic figure which shows the example of the threshold value of the radio | wireless communication apparatus of this invention. The system outline figure for explaining the example of control of the radio communications equipment of the present invention. The flowchart which shows the other example of control of the transmission side of the radio | wireless communication apparatus of this invention. The flowchart which shows the example of the conventional transmission power control. The flowchart which shows the other example of conventional transmission power control. The block diagram which shows the other example of conventional transmission power control. It is a flowchart which shows the example of the conventional transmission power control, (a) is a flowchart of a main | base station, (b) is a flowchart of a subunit | mobile_unit.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1, 11 thru | or 16 Wireless communication apparatus, 2 Transmission part, 3 Reception part, 4 Control part, 5 Antenna, 6 Transmission / reception changeover switch, 7 Speaker, 8 Storage part, 9 Comparator, 10 Analog / digital converter

Claims (4)

In a wireless communication device having a transmission unit and a reception unit,
The reception unit includes a connection request signal detection unit that detects a connection request signal transmitted from another wireless communication device, a reception electric field level detection unit that detects an electric field strength of a reception signal including the connection request signal, and the detection When the received electric field level is equal to or lower than the threshold value as a result of the comparison by the received electric field level comparing means for comparing the received electric field level value with a preset received electric field level threshold value and the received electric field level comparing means, the connection response signal A connection response signal indicating means for instructing transmission, and a connection response signal returned from another wireless communication device in response to a connection request signal transmitted from the transmission unit, and connection response signal detection information Connection response signal detection means for supplying to the transmission unit,
The transmission unit transmits transmission power switching means for switching transmission power to at least two high and low levels, and transmits a connection request signal with high transmission power at the start of communication, and connection response signal detection means for the reception unit within a predetermined time. Transmission power control means for maintaining the transmission power at a high level when receiving connection response signal detection information from the transmission power, and switching the transmission power to a low level when not receiving connection response signal detection information within a predetermined time; and the reception And a means for transmitting a connection response signal upon receiving a connection response signal instruction from the unit.   2. The wireless communication device according to claim 1, wherein the transmission unit includes means for switching a transmission power level in three or more steps, and is returned from another wireless communication device in response to the connection request signal transmitted at the start of communication. A wireless communication apparatus having a transmission power control function, characterized by comprising means for sequentially switching a transmission power level in a decreasing direction until a signal is detected and transmitting a connection request signal.   3. The radio communication apparatus according to claim 1, wherein the reception electric field level detection means is an RSSI detection means or a signal detection means corresponding to communication quality. Machine.   The wireless communication device according to any one of claims 1 to 3, wherein the wireless communication device has a function of selectively calling one or more specific wireless communication devices. A wireless communication apparatus having a transmission power control function, wherein the connection request signal and the connection response signal are exchanged between each other.

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