JP2007036795A - Wireless communication apparatus and power control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wireless communication apparatus capable of executing transmission at a maximum power independently of a connected apparatus by controlling a reception diversity operation. <P>SOLUTION: The wireless communication apparatus provided with a reception diversity means connected to an electronic apparatus and receiving supply of power from the electronic apparatus to carry out wireless communication with an external station includes: a maximum transmission power value setting means that reads a voltage of the electronic apparatus and sets a maximum transmission power value from the read voltage; and a control means that compares a transmission power value to the external station with the maximum transmission power value and controls the reception diversity means to deactivate its operation when the transmission power value to the external station is greater than the maximum transmission power value. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a radio communication apparatus that performs reception diversity and a power control method thereof.

Conventionally, a wireless communication apparatus provided with a reception diversity circuit is known, but the circuit control method in such an apparatus is roughly divided into the following three. The first is a selection formula typified by a method of selecting one of the two receivers having the higher reception level, and the second is that a main receiver is determined and the main receiver is below a certain level. A switching type represented by a method of switching to a sub-receiver when the reception level is reached, and the third is a method of synthesizing two signals while keeping two receivers in a reception state, although it is slightly different from the control. Is a synthesis formula. The selection type includes an antenna diversity switch that selects an antenna having a good reception state among a plurality of antennas, and can switch antennas (see, for example, Patent Document 1). For the switching type, several diversity switching methods for low power consumption have been proposed. For example, there is a method in which two reception circuits are alternately switched in time during standby (see, for example, Patent Document 2). ). The synthesis formula is basically a method of always receiving signals simultaneously in two systems and synthesizing signals (for example, see Patent Document 3).
JP-A-9-181660 JP-A-5-252094 JP 2000-1965630 A

  By the way, as a wireless communication apparatus including the reception diversity circuit as described above, for example, a PC card, a USB terminal, etc., which are connected to a device such as a personal computer or a PDA and operate by receiving power supply from the device are known. However, such PC cards and USB terminals have the following problems.

  That is, the PC card, USB terminal, and the like as described above generally have an upper limit of operating current of about 1000 mA, but such an upper limit may not be realized depending on the personal computer to be connected. Specifically, there is usually no problem if the upper limit of the current used is 1000 mA. However, in consideration of the efficiency of the DC-DC converter and the like, when data transmission is performed at the maximum power value, the current used is increased to 1000 mA. In this case, the voltage drops, which hinders the driving of the device.

For such a problem, conventionally, the maximum transmission power value at the time of transmission is set to a low value in advance, or control such as lowering the maximum transmission power value when some threshold is exceeded, Although these controls are effective for current limiting, the transmission power is reduced for the original communication, and as a result, the communicable area is narrowed. In other words, although transmission is desired with the maximum power value, transmission power is controlled so that the transmission wave does not reach the base station.
The present invention has been made in view of such circumstances, and provides a wireless communication device and a power control method capable of transmitting at maximum power regardless of the connected device by controlling the reception diversity operation. With the goal.

  The present invention is a wireless communication apparatus including a reception diversity unit that is connected to an electronic device, receives power supply from the electronic device, and performs wireless communication with an external station, and reads and reads a voltage value of the electronic device. The maximum transmission power value setting means for setting the maximum transmission power value from the voltage value, the transmission power value to the external station and the maximum transmission power value are compared, and the transmission power value to the external station is the maximum And control means for controlling to turn off the operation of the reception diversity means when the transmission power value is larger than the transmission power value.

  In the present invention, the control means compares the transmission power value to the external station and the maximum transmission power value, and when the transmission power value to the external station is smaller than the maximum transmission power value, Control is performed to turn on the operation of the reception diversity means.

  The present invention relates to a power control method for a wireless communication apparatus provided with a reception diversity means for connecting to an electronic device and receiving power supply from the electronic device and performing wireless communication with an external station, the voltage value of the electronic device being The maximum transmission power value setting step for setting the maximum transmission power value from the read voltage value, the transmission power value to the external station and the maximum transmission power value are compared, and the transmission power to the external station And a control step for controlling to turn off the operation of the reception diversity means when the value is larger than the maximum transmission power value.

  The present invention compares the transmission power value to the external station and the maximum transmission power value in the control step, and when the transmission power value to the external station is smaller than the maximum transmission power value, Control is performed to turn on the operation of the reception diversity means.

  According to the present invention, the transmission power value to the base station is compared with the maximum transmission power value set based on the voltage value of the electronic device to be connected, and the transmission power value exceeds the maximum transmission power value. In addition, since the reception diversity operation is turned off, the power consumption can be reduced. Also, by turning off the receive diversity operation, the power consumed by the receive diversity circuit can be used as the power to improve the transmission performance. The effect that the reduction of the communicable area by setting the power value to a low value can be avoided is also obtained.

  Hereinafter, a wireless communication apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the embodiment. In the following description, as an example, communication is performed by connecting a data communication card of 1xEV-DO (technical specification for data communication included in the “cdma2000” standard) equipped with two reception diversity circuits to a personal computer. explain. In FIG. 1, a symbol C is a 1 × EV-DO data communication card. Reference numerals 12A and 12B are two systems (first and second) receiving units for performing reception diversity, and two different antennas 11A and 11B are connected to each other. Reference numeral 13 denotes an electric field strength measuring unit that measures the electric field strengths of the first receiving unit 12A and the second receiving unit 12B. Reference numeral 14 denotes an electric field strength discriminating unit that discriminates the value of the electric field strength measured by the electric field strength measuring unit 13 and evaluates the reception state. Reference numeral 15 denotes a determination unit that determines whether or not to turn off the reception diversity operation. Reference numeral 16 denotes a battery monitoring unit that reads the voltage value of the external battery 19 provided in the personal computer 20. Reference numeral 17 denotes a diversity control unit that controls on / off of the reception diversity operation by the first receiving unit 12A and the second receiving unit 12B based on the result of determination by the determining unit 15. Reference numeral 21 denotes a transmission power monitoring unit that monitors the transmission power of the transmission unit 18. Reference numeral 22 denotes a maximum transmission power value setting unit that sets the value of the maximum transmission power of the transmission unit 18. Reference numeral 23 denotes a reference table storage unit that stores a reference table in which a relationship between current consumption and transmission power is defined in advance. Reference numeral 24 denotes a maximum transmission power value storage unit that stores the maximum transmission power value of the transmission unit 18 set by the maximum transmission power value setting unit 22. Reference numeral 25 denotes a communication control unit for performing communication via the first reception unit 12A, the second reception unit 12B, and the transmission unit 18. The battery monitoring unit 16, the maximum transmission power value setting unit 22, the reference table storage unit 23, and the maximum transmission power value storage unit 24 correspond to the maximum transmission power value setting unit (symbol A) according to the present invention, and the determination unit 15 The diversity control unit 17 and the transmission power monitoring unit 21 correspond to the control means (symbol B) according to the present invention.

  Next, the operation of the data communication card C shown in FIG. 1 will be described with reference to FIG. First, when the main power is turned on, it waits until it reaches a steady state (steps S1 and S2). And the battery monitoring part 16 reads the power supply condition (voltage value of the external battery 19) of the external battery 19 (step S3). Normally, a PCMCIA card or the like has a power supply voltage specification of 3.3V ± 0.3V, and an approximate maximum supplyable current value can be predicted from the voltage value. Since this voltage value may vary depending on the personal computer 20, the voltage value of the external battery 19 is read when the power is turned on, so that the connected device (here, the personal computer 20) to which the data communication card C is connected can cope with different power environments. It becomes possible. For example, if the voltage of the external battery 19 is 3.3 V, a booster circuit operates in the data communication card C to generate necessary power. Since the maximum current value is 1000 mA, if it is simply converted to 3.6 V, the current that can be used in the data communication card C is 916 mA. If the external battery 19 is 3.0 V, the maximum current of 1000 mA does not change, so that a current of 833 mA can be used. Since this is an example where the efficiency is 100%, the current actually decreases further. Therefore, if a table defining the relationship between current consumption and transmission power is prepared, it is possible to cope with changes in the voltage value of the external battery 19.

  Next, the maximum transmission power value setting unit 22 is a table that defines the relationship between the voltage value of the external battery 19, the current consumption stored in the reference table storage unit 23 and the transmission power, and the diversity circuit in the data communication card C. The current consumption value is referred to (step S4). Then, the maximum transmission power value setting unit 22 sets the maximum transmission power value when the reception diversity operation is in the on state and the maximum transmission power value when the reception diversity operation is in the off state (step S5), and maximum transmission of both the set values. It memorize | stores in the electric power value memory | storage part 24 (step S6). Thus, the maximum transmission power value storage unit 24 stores the respective maximum transmission power values when the reception diversity operation is turned on / off.

  Next, the diversity control unit 17 turns on the reception diversity operation and shifts to the normal standby state (step S7). On the other hand, the transmission power monitoring unit 21 constantly monitors the transmission power to the base station (external station) and notifies the determination unit 15 of the obtained transmission power value (step S8). The determination unit 15 compares the transmission power value notified from the transmission power monitoring unit 21 with the maximum transmission power value stored in the maximum transmission power value storage unit 24 when the reception diversity operation is on (step). S9). Then, if the transmission power value exceeds the maximum transmission power value when the reception diversity operation is on (if transmission power value> maximum transmission power value is satisfied), the determination unit 15 causes the diversity control unit 17 to On the other hand, an instruction to turn off the reception diversity operation (request signal) is output. In response to this, the diversity control unit 17 turns off one of the first receiving unit 12A and the second receiving unit 12B (turns the reception diversity operation off) and switches to the low power consumption mode. (Step S10).

  Next, the determination unit 15 refers to the reception state in the OFF state of the reception diversity operation notified from the electric field strength determination unit 14, and evaluates the current reception state (step S11). As a result of this evaluation, it is determined whether or not reception is possible even in the state of one system (step S12). As a result of this determination, when it is determined that it is difficult to receive in the state of one system, the determination unit 15 outputs an instruction to turn on the reception diversity operation to the diversity control unit 17. In response to this, the diversity control unit 17 turns on the reception diversity operation and returns to the normal mode (step S7). On the other hand, when the signal can be received even in the state of one system, the determination unit 15 reads the transmission power value notified from the transmission power monitoring unit 21 (step S13), and the transmission power value and the maximum transmission power value storage unit 24. Is compared with the maximum transmission power value stored in the ON state of the reception diversity operation (step S14). If the transmission power value does not exceed the maximum transmission power value when the reception diversity operation is on (if transmission power value <maximum transmission power value is satisfied), the determination unit 15 causes the diversity control unit 17 to On the other hand, an instruction to turn on the reception diversity operation is output. In response to this, the diversity control unit 17 turns on the reception diversity operation and returns to the normal mode (step S7).

  Next, the operation shown in FIG. 2 will be described with a specific example. First, the battery monitoring unit 16 measures the voltage of the external battery 19 (step S3). As a result of the measurement, when the voltage of the battery 19 is 3.3 V, since the maximum current value is 1000 mA, the data communication card C can be used up to a current of 916 mA. Here, in order to simplify the description, it is assumed that the efficiency is 100%. FIG. 3 shows a relationship between the current stored in the reference table storage unit 23 and the transmission power. From this figure, it can be seen that a current of 950 mA is required at 24 dBm and a current of 900 mA at 22 dBm, and that a transmission power of approximately 23 dBm is possible at 916 mA. At 24 dBm output, the power that can be supplied from the external battery 19 may be exceeded and the system may be down. Therefore, the maximum power is set in consideration of the safety factor. For example, the maximum transmission power value setting unit 22 sets the maximum transmission power value to 22 dBm. Then, the value of 22 dBm is stored in the maximum transmission power value storage unit 24. If the current consumption of the reception diversity circuit is 50 mA, a margin of 50 mA is generated by turning off the reception diversity operation. That is, by turning off the reception diversity operation, the transmission power is 24 dBm output, the current consumption of the entire data communication card C is 900 mA, and the 22 dBm output is 850 mA, and the current is reduced by 50 mA. As a result, the maximum current that can be supplied is less than 916 mA, so the maximum transmittable power setting can be increased to 24 dBm instead of 22 dBm, and transmission power reduction can be improved by 2 dB by turning off the receive diversity operation. Can do. Here, the maximum transmission power value setting unit 22 stores the maximum transmission power value in the off state of the reception diversity operation as 24 dBm in the maximum transmission power value storage unit 24 (steps S4 to S6).

  Next, after setting the maximum transmission power value when the reception diversity operation is ON / OFF, the state shifts to the normal use state (step S7). Normally, the reception diversity operation is turned on and used. However, if a request to increase the transmission power value to 22 dBm or more is made by the transmission power control from the base station, the allowable current value will be exceeded as it is, so that it exceeds 22 dBm. However, the transmission power of 22 dBm or more can be achieved by turning off the reception diversity operation. However, at 24 dBm or more, the current consumption reduction effect by setting the reception diversity operation to the off state is exceeded, so that it cannot exceed 24 dBm. When there is a request to reduce the transmission power to 22 dBm or less by the transmission power control from the base station, the reception diversity operation is turned on (steps S8 to S14).

  Next, an example in which the above-described data communication card C is connected to another connected device will be described. When the external battery of the connected device is 3.0 V, the data communication card C can use a current of 833 mA. From the diagram showing the relationship between the current and the transmission power shown in FIG. 3, it can be obtained that the output is 18 dBm and becomes 830 mA. When the reception diversity operation is on, the maximum transmission power is limited to 18 dBm. If the reception diversity operation is similarly turned off by 50 mA, the upper limit is set to 880 mA. From FIG. 3, it is 900 mA at 22 dBm and 855 mA at 20 dBm, so that it is 21 dBm at 880 mA, and the maximum transmission power when the reception diversity operation is off can be reduced to 21 dBm. As a result, an improvement of 3 dB can be expected. When a request of 18 dBm or more is received by the transmission power control from the base station, the reception diversity operation is set to the off state and the transmission power upper limit is increased to 21 dBm. When the request is 18 dBm or less, the reception diversity operation is used in the on state. It becomes possible.

  As described above, the purpose of the conventional diversity control is mainly to improve the reception performance due to the diversity effect and to achieve low power consumption while maintaining stable reception, whereas the wireless communication according to the present invention. Since the device controls reception diversity as a measure against transmission performance instead of control for reception performance, when there is a current limitation due to an external battery, etc., the reception diversity operation is turned off when the maximum transmission power is output. By setting the state, it is possible to avoid a decrease in the communicable area due to the transmission power down control and setting the maximum power setting value lower.

  FIG. 4 shows an example of the relationship between the output of the power amplifier and the current. In the RF circuit, the circuit after the power amplifier has a circuit loss of about 3 to 4 dB. This circuit loss is assumed to be 3 dB here. If the transmission power at the antenna end is 24 dBm, the power amplifier output is 27 dBm, so the current at 27 dBm is about 380 mA from FIG. Since it is about 340 mA at 26 dBm when it is lowered by 1 dB, it can be seen that the current is lowered by about 40 mA by reducing 1 dB from the maximum transmission power.

  On the other hand, a current of 50 mA to 60 mA is required for the LNA and the demodulation IC. This is an example of direct conversion, but in heterodyne, current tends to increase slightly. In the case of diversity of two reception systems, a current of 100 mA is used for reception. From this, it can be seen that the current of 50 mA is reduced when the current for one reception system is reduced by turning off the reception diversity operation.

  From the above, it can be seen that a current reduction effect equivalent to or higher than that obtained by controlling the transmission power can be obtained by turning off the reception diversity operation when the maximum transmission power is output. In this example, the reception is two systems, but a terminal equipped with many receivers can be expected to further increase the current reduction effect.

  In this way, when there is a current limit due to an external battery, etc., communication is possible by setting the transmission power down control and the maximum transmission power value lower by turning off the reception diversity operation when the maximum transmission power is output. Can be avoided. Here, the case of outputting the maximum transmission power has been described, but the same effect can be obtained by performing the same control even if the current or the like is limited before reaching the maximum output.

  The wireless communication apparatus of the present invention is not limited to being mounted on a data communication card, but is mounted on a USB terminal or the like.

It is a block diagram which shows the structure of one Embodiment of this invention. It is a flowchart which shows operation | movement of the apparatus shown in FIG. It is explanatory drawing which shows the relationship between an electric current and output electric power. It is explanatory drawing which shows the relationship between an electric current and transmission power.

Explanation of symbols

11A, 11B ... Antenna, 12A ... First receiving unit, 12B ... Second receiving unit, 13 ... Electric field strength measurement unit, 14 ... Electric field strength determination unit, 15 ... Determination unit , 16 ... Battery monitoring unit, 17 ... Diversity control unit, 18 ... Transmission unit, 19 ... External battery, 20 ... Personal computer, 21 ... Transmission power monitoring unit, 22 ... Maximum transmission power value setting unit, 23... Adjustment value storage unit, 24... Maximum transmission power value storage unit, 25.

Claims (4)

A wireless communication device comprising a reception diversity means for connecting to an electronic device and receiving power supply from the electronic device to perform wireless communication with an external station,
A maximum transmission power value setting means for reading a voltage value of the electronic device and setting a maximum transmission power value from the read voltage value;
The transmission power value to the external station is compared with the maximum transmission power value, and when the transmission power value to the external station is larger than the maximum transmission power value, the operation of the reception diversity means is turned off. And a control means for controlling the wireless communication device.   The control means compares the transmission power value to the external station and the maximum transmission power value, and when the transmission power value to the external station is smaller than the maximum transmission power value, the reception diversity means The wireless communication apparatus according to claim 1, wherein the wireless communication apparatus is controlled to turn on the operation. A power control method for a wireless communication device comprising a reception diversity means for connecting to an electronic device and receiving power supply from the electronic device and performing wireless communication with an external station,
A maximum transmission power value setting step for reading a voltage value of the electronic device and setting a maximum transmission power value from the read voltage value;
The transmission power value to the external station is compared with the maximum transmission power value, and when the transmission power value to the external station is larger than the maximum transmission power value, the operation of the reception diversity means is turned off. And a control step for controlling the power. In the control step, the transmission power value to the external station is compared with the maximum transmission power value, and if the transmission power value to the external station is smaller than the maximum transmission power value, the reception diversity means The power control method according to claim 3, wherein the control is performed so that the operation is turned on.

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