JP2011171963A - Communication equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide communication equipment that achieves power-saving without causing communication error or significantly changing sensitivity. <P>SOLUTION: A difference is calculated between an output signal of a variable gain phase shifting part 4 that increases/decreases a gain of the output of a noise sensor part 3 that acquires noise and a radio signal received from an antenna 2 that receives the radio signal from the outside. The gain of the variable gain phase shifting part 4 is controlled based on a reception quality index (BER, C/N, RSSI, or AGC control value) which is based on the above difference. When the gain becomes smaller than a predetermined value, supply of electric power to the variable gain phase shifting part 4 is stopped. Thus, energy saving is attained without causing communication error or significantly changing sensitivity. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a communication device such as a mobile phone and a PDA (Personal Digital Assistant).

  2. Description of the Related Art Conventionally, in small communication devices such as a mobile phone and a PDA, the casing has been reduced in size and thickness because importance is placed on portability. In addition, as the housing becomes smaller and thinner, it is required to reduce the size and power consumption of the battery. As conventional techniques for achieving power saving, for example, those described in Patent Document 1 and Patent Document 2 are known. In Patent Document 1, when a BER (Bit Error Rate) output from an error correction unit is larger than a predetermined threshold value, diversity reception is performed by supplying power to two tuner units. A technique is described in which, when the BER is smaller than the threshold, single reception is performed by stopping power supply to one of the two tuner sections. Patent Document 2 describes a technique for switching on / off a pre-amplifier unit located in a pre-stage of a tuner based on a MER (Modulation Error Rate) measurement value.

JP 2006-31258 A JP 2009-088807 A

  However, in the prior art described in Patent Document 1 described above, it is difficult to assume in advance a reception state after stopping the switching operation between diversity reception and single reception, and thus there is a problem that a communication error may occur. is there. In particular, there is a problem when switching from diversity reception to single reception, and a communication error may occur when the BER is smaller than the threshold and the BER is changed to be larger than the threshold even though the BER is switched to single reception.

  Further, in the conventional technique described in Patent Document 2 described above, the control of the pre-amplifier unit is limited to either on or off, and there is a problem that the sensitivity changes greatly with switching.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a communication device capable of saving power without causing a communication error and without greatly changing sensitivity.

  The communication device of the present invention includes an antenna that receives an external radio signal, a noise sensor unit that acquires noise, a variable gain phase shift unit that increases or decreases the gain of the output of the noise sensor unit, and the variable gain phase shift An adder that takes a difference between the output signal of the unit and the radio signal received from the antenna, and reduces the gain based on a reception quality index based on the output of the adder, and the gain is equal to or less than a predetermined value. In this case, the power supply to the variable gain phase shifter is stopped.

  According to the above configuration, the difference between the output signal of the variable gain phase shifter that increases or decreases the output gain of the noise sensor unit and the received radio signal is taken, and the variable gain phase shift is performed based on the reception quality indicator based on this difference. Since the gain of the unit is continuously changed, it is possible to save power without causing a communication error or greatly changing the sensitivity.

  In the above configuration, the predetermined value is substantially zero.

  In the above configuration, the reception quality indicator is BER, and the gain of the variable gain phase shifter is decreased as the BER decreases.

  In the above configuration, the reception quality index is C / N, and the gain of the variable gain phase shifter is decreased as the C / N increases.

  In the above configuration, the reception quality index is RSSI, and the gain of the variable gain phase shifter is decreased as the RSSI increases.

  In the above configuration, the reception quality index is set as an AGC control value, and the gain of the variable gain phase shifter is decreased as the AGC control value decreases.

  In the above configuration, the BER and C / N are obtained from a demodulator connected to the output of the adder.

  In the above configuration, the RSSI and AGC control values are obtained from a tuner connected to the output of the adder.

  In the above configuration, the variable gain phase shifter is configured by a plurality of variable gain amplifiers, and the power supply to the plurality of variable gain amplifiers is stopped one by one in conjunction with the control for reducing the gain.

  The present invention can save power in a communication device such as a mobile phone or a PDA without causing a communication error and without greatly changing sensitivity.

The block diagram which shows schematic structure of the communication apparatus which concerns on one embodiment of this invention The figure which shows the characteristic of BER The figure which shows the characteristic of C / N The figure which shows the characteristic of RSSI The figure which shows the characteristic of AGC control value The figure for demonstrating control operation | movement of the communication apparatus of FIG. 1 when a reception quality parameter | index is set to C / N FIG. 1 is a flowchart showing an active noise canceller activation control operation of the communication device of FIG. 1 when the reception quality index is BER. FIG. 1 is a flowchart showing an active noise canceller activation control operation of the communication device of FIG. 1 when the reception quality index is C / N. FIG. 1 is a flowchart showing an active noise canceller activation control operation of the communication device of FIG. 1 when the reception quality index is RSSI. FIG. 1 is a flowchart showing an active noise canceller activation control operation of the communication device in FIG. 1 when the reception quality index is an AGC control value. The block diagram which shows schematic structure of the application example of the communication apparatus of FIG.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments for carrying out the invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram showing a schematic configuration of a communication device according to an embodiment of the present invention. In the figure, the communication device 1 of the present embodiment generates a waveform having a phase opposite to that of the interference noise component superimposed on the desired wave signal (that is, a phase opposite to that of the interference noise component generated inside the communication device). It has a function of obtaining a noise canceling effect by adding to a desired wave signal, and includes an antenna 2 that receives a radio signal from the outside, a noise sensor unit 3 that acquires noise, and a gain of an output of the noise sensor unit 3 Variable gain phase shifter 4 for increasing / decreasing the frequency, adder 5 for taking the difference between the output signal of variable gain phase shifter 4 and the radio signal received from antenna 2, and the radio signal output from adder 5 A tuner 6 that extracts a channel modulation signal, a demodulator 7 that demodulates and outputs digital data (TS: Transport Stream) from a signal selected by the tuner 6, and a BER ( The gain of the variable gain phase shifter 4 is changed on the basis of Bit Error Rate) or C / N (Carrier to Noise ratio), and when the gain becomes smaller than a predetermined value, the variable gain phase shift is performed. And a controller 8 for stopping power supply to the unit 4. The noise sensor unit 3, the variable gain phase shift unit 4, the adder 5 and the controller 8 constitute a noise canceller.

  The variable gain phase shifter 4 includes one variable gain amplifier 41 and one variable phase shifter 42. The BER and C / N are reception quality indicators. FIG. 2 shows BER characteristics and FIG. 3 shows C / N characteristics. The BER characteristic is a characteristic that the BER decreases when the signal-to-noise ratio (S / N) increases, and the C / N characteristic is a characteristic that the C / N increases when the signal-to-noise ratio increases. Accordingly, the controller 8 decreases the gain as the BER decreases when the reception quality index is BER, and decreases the gain as C / N increases when the reception quality index is C / N.

  More specifically, the controller 8 determines the optimum adjustment state of the variable gain phase shifter 4 while maintaining the sensitivity point threshold values (BER: X, C / N: Y) of the BER and C / N reception quality indexes. By reducing the gain coefficient α as a reference, the amount of noise cancellation is suppressed in stages, and when α = 0 is finally reached, control is performed to stop the operation of the variable gain phase shifter 4. On the other hand, when the controller 8 determines that there is a possibility that the BER or C / N reception quality index does not satisfy the sensitivity point threshold condition, the controller 8 stops the reduction control of α or returns it to α = 1. The control step of α is determined based on the maximum slope of the BER or C / N characteristic. The predetermined value compared with the gain of the variable gain phase shifter 4 is substantially a value of “0 (zero)”.

  The reception quality indicator may be an RSSI (Received Signal Strength Indicator) or an AGC (Automatic Gain Control) control value in addition to the BER and C / N. FIG. 4 shows the RSSI characteristics, and FIG. 5 shows the AGC control value characteristics. In the case of RSSI, a measurement error occurs due to noise power, and actual characteristics are shown by dotted lines. ΔP shown in FIG. 4 is a measurement error. In the case of the AGC control value, the AGC control value is determined based on RSSI in order to keep the amplitude of the input signal at a constant value.

  The RSSI characteristic is a characteristic that the RSSI increases when the signal-to-noise ratio increases, and the characteristic of the AGC control value is a characteristic that the AGC control value decreases as the signal-to-noise ratio increases. Thereby, the controller 8 decreases the gain as the RSSI increases when the reception quality index is RSSI, and decreases the gain as the AGC control value decreases when the reception quality index is the AGC control value. The sensitivity point in the case of RSSI is P, and the sensitivity point in the case of an AGC control value is Q. The AGC control value and the RSSI have opposite characteristics (inclination is reversed). The RSSI and AGC control values can be obtained from the tuner 6.

Here, the stepwise switching control of the gain coefficient α by C / N will be described in detail with reference to the C / N characteristic diagram shown in FIG. C / N (dB) can be derived from equation (1). The noise power (dB) can be derived from the equation (2).
[Basic expression]
C / N calculation formula (dB): CNR = 10 log (D / U) (1)
Noise power (dB): 10 log (U) = 10 log {N _T + (1-α} N _MAX (2)
However, CNR: C / N, D: desired wave power, U: noise power, N _T : stationary noise such as thermal noise component (known for each system), N (t): interference noise component ... burst noise that varies with time , N _MAX : interference noise component maximum value (known for each system), α: noise canceller gain coefficient

[Control procedure]
[1] Control from initial state α = 1 (maximum noise suppression effect) to α _{1 The} C / N measurement value obtained from the demodulator 7 at this time is y ₀ , and the sensitivity point C / N that becomes the reception limit If Y is Y, the noise power does not adversely affect reception even if the difference y ₀ -Y increases. If the maximum slope of the C / N output characteristic with respect to the power ratio is k, the gain coefficient α1 in the _first control can be derived from the equation (3).
10 log {N _T + (1−α ₁ ) N _MAX } = 10 log (N _T ) + k (y ₀ −Y) (3)
Therefore, α ₁ = 1 + N _T / N _MAX × {1-10 ^{((y0−Y) k / 10)} }.

[2] Control from α ₁ to α _{2 If the} C / N measurement value obtained from the demodulator 7 at this time is y ₁ , the noise power increases in the difference y ₁ -Y between the two as in [1]. Even if it does not adversely affect reception, the gain coefficient α ₂ in the second control can be derived from the equation (4).
10 log {N _T + (1−α ₂ ) N _MAX } = 10 log {N _T + (1−α ₁ ) N _MAX } + k (y ₁ −Y) (4)
Therefore, α ₂ = 1 + N _T / N _MAX − {1 + N _T / N _MAX −α ₁ } × {10 ^{((y 1 −Y) k / 10)} }.

[3] Control from α ₂ to α ₃ Similarly to [2], the calculation of the gain coefficient is repeated sequentially.
As a result of the calculation, when the gain coefficient α = 0, the operation of the variable gain phase shifter 4 is turned off.

The stepwise switching control of the gain coefficient α by C / N has been described above. Even when the BER, RSSI, and AGC control values are used, the characteristic gradient k and the output difference between the observed value and the sensitivity point (y ₀ -Y) The same control can be performed by changing only the method of obtaining the above.

Next, the operation of the active noise canceller of the communication device 1 of the present embodiment will be described for each reception quality index of BER, C / N, RSSI, and AGC control value.
“When the reception quality index is BER”
FIG. 7 is a flowchart showing an active noise canceller (ANC) activation control operation of the communication device 1 when the reception quality index is BER. In the figure, it is first determined whether or not the active noise canceller is on (step 1). If the active noise canceller is on, BER is measured (step 2). After measuring the BER, it is determined whether or not the value is less than the sensitivity point X1 (step 3). If the value is less than the sensitivity point X1, the gain coefficient α is changed. That is, α _{i is set} to α _{i + 1} (step 4). After finishing the process of step 4, it returns to step 1. In this way, while the active noise canceller is in the on state, the gain coefficient α is changed by measuring the BER until the BER becomes equal to or higher than the sensitivity point X1.

  If it is determined in step 3 that the BER is not less than the sensitivity point X1, that is, if it is greater than or equal to the sensitivity point X1, it is determined whether or not the sensitivity point X2 is exceeded (step 5). However, X1 <X2. When the BER exceeds the sensitivity point X2, the active noise canceller is turned on and the gain coefficient α is set to “1”. When the process proceeds from step 3 to step 5, the active noise canceller is in the on state, so only the gain coefficient α is set. On the other hand, if the BER is equal to or less than the sensitivity point X2, no processing is performed and the process returns to step 1. On the other hand, if the active noise canceller is not in the ON state in the determination in step 1, the process proceeds to step 5.

  Thus, when the active noise canceller is in the ON state, the BER is measured. If the measured BER is less than the sensitivity point X1, the gain coefficient α is changed, and this process is repeated until the BER exceeds the sensitivity point X1. Thereafter, when the BER exceeds the sensitivity point X1 and further exceeds the sensitivity point X2 (X1 <X2), the gain coefficient α is set to “1”. When the active noise canceller is not turned on, the active noise canceller is turned on when the BER exceeds the sensitivity point X2, and the gain coefficient α is set to “1”.

“When the reception quality index is C / N”
FIG. 8 is a flowchart showing an active noise canceller activation control operation of the communication device 1 when the reception quality index is C / N. In the figure, it is first determined whether or not the active noise canceller is on (step 10). If the active noise canceller is on, C / N is measured (step 11). After measuring C / N, it is determined whether the value exceeds the sensitivity point Y1 (step 12). If the value exceeds the sensitivity point Y1, the gain coefficient α is changed. That is, α _{i is set} to α _{i + 1} (step 13). After finishing the process of step 13, it returns to step 10. In this way, while the active noise canceller is in the on state, the gain coefficient α is changed by measuring C / N until C / N becomes equal to or lower than the sensitivity point Y1.

  If it is determined in step 12 that C / N is equal to or less than the sensitivity point Y1, it is further determined whether or not the sensitivity point is less than Y2 (step 14). However, Y1> Y2. When C / N is less than the sensitivity point Y2, the active noise canceller is turned on and the gain coefficient α is set to “1”. When the process proceeds from step 12 to step 14, the active noise canceller is in the on state, and therefore only the gain coefficient α is set. On the other hand, if C / N exceeds the sensitivity point Y2, no processing is performed and the process returns to step 10. On the other hand, if the active noise canceller is not in the ON state in the determination in step 10, the process proceeds to step 14.

  In this way, C / N is measured when the active noise canceller is in the on state, and if the measured C / N exceeds the sensitivity point Y1, the gain coefficient α is changed, and this processing is performed with C / N equal to or less than the sensitivity point Y1. Repeat until. Thereafter, when C / N becomes equal to or less than the sensitivity point Y1, and further becomes less than the sensitivity point Y2 (X1 <X2), the gain coefficient α is set to “1”. When the active noise canceller is not in the on state, the active noise canceller is turned on by setting C / N to be less than the sensitivity point Y2, and the gain coefficient α is set to “1”.

"When the reception quality index is RSSI"
FIG. 9 is a flowchart showing an active noise canceller activation control operation of the communication device 1 when the reception quality index is RSSI. In the figure, it is first determined whether or not the active noise canceller is on (step 20). If the active noise canceller is on, RSSI is measured (step 21). After measuring the RSSI, it is determined whether or not the value exceeds the sensitivity point P1 (step 22). If the value exceeds the sensitivity point P1, the gain coefficient α is changed. That is, α _{i is set} to α _{i + 1} (step 23). After finishing the process of step 23, it returns to step 20. In this way, while the active noise canceller is in the on state, the RSSI is measured until the RSSI becomes the sensitivity point P1 or less, and the gain coefficient α is changed.

  If it is determined in step 22 that the RSSI is equal to or less than the sensitivity point P1, it is further determined whether or not it is less than the sensitivity point P2 (step 24). However, P1> P2. When the RSSI is less than the sensitivity point P2, the active noise canceller is turned on and the gain coefficient α is set to “1”. When the process proceeds from step 22 to step 24, the active noise canceller is in the on state, so only the gain coefficient α is set. On the other hand, if the RSSI exceeds the sensitivity point P2, no processing is performed and the process returns to step 20. On the other hand, if it is determined in step 20 that the active noise canceller is not on, the process proceeds to step 24.

  In this way, RSSI is measured when the active noise canceller is in the ON state. If the measured RSSI exceeds the sensitivity point P1, the gain coefficient α is changed, and this process is repeated until the RSSI becomes equal to or less than the sensitivity point P1. Thereafter, when the RSSI becomes equal to or lower than the sensitivity point P1, and further becomes less than the sensitivity point P2 (P1> P2), the gain coefficient α is set to “1”. When the active noise canceller is not turned on, the active noise canceller is turned on by setting the RSSI below the sensitivity point P2, and the gain coefficient α is set to “1”.

“When the reception quality index is an AGC control value”
FIG. 10 is a flowchart showing an active noise canceller activation control operation of the communication device 1 when the reception quality index is an AGC control value. In the figure, it is first determined whether or not the active noise canceller is on (step 30). If the active noise canceller is on, an AGC control value is acquired (step 31). After acquiring the AGC control value, it is determined whether the value is less than the sensitivity point Q1 (step 32). If the value is less than the sensitivity point Q1, the gain coefficient α is changed. That is, α _{i is set} to α _{i + 1} (step 33). After finishing the process of step 33, it returns to step 30. In this way, while the active noise canceller is in the on state, the AGC control value is acquired and the gain coefficient α is changed until the AGC control value becomes equal to or higher than the sensitivity point Q1.

  If it is determined in step 32 that the AGC control value is not less than the sensitivity point Q1, that is, if it is greater than or equal to the sensitivity point Q1, it is determined whether or not the sensitivity point Q2 is exceeded (step 34). However, Q1 <Q2. When the AGC control value exceeds the sensitivity point Q2, the active noise canceller is turned on and the gain coefficient α is set to “1”. When the process proceeds from step 32 to step 34, the active noise canceller is in the on state, so only the gain coefficient α is set. On the other hand, if the AGC control value is equal to or less than the sensitivity point Q2, no processing is performed and the process returns to step 30. On the other hand, if the active noise canceller is not in the ON state as determined in step 30, the process proceeds to step 34.

  As described above, the AGC control value is acquired when the active noise canceller is in the ON state. If the acquired AGC control value is less than the sensitivity point Q1, the gain coefficient α is changed, and this processing is performed so that the AGC control value exceeds the sensitivity point Q1. Repeat until. Thereafter, when the AGC control value exceeds the sensitivity point Q1 and further exceeds the sensitivity point Q2 (Q1 <Q2), the gain coefficient α is set to “1”. When the active noise canceller is not turned on, the active noise canceller is turned on when the AGC control value exceeds the sensitivity point Q2, and the gain coefficient α is set to “1”.

  As described above, according to the communication device 1 of the present embodiment, the antenna that receives the output signal of the variable gain phase shifter 4 that increases or decreases the gain of the output of the noise sensor unit 3 that acquires noise and the radio signal from the outside. 2 is used to control the gain of the variable gain phase shifter 4 based on a reception quality index (BER, C / N, RSSI, or AGC control value) based on the difference. Since the power supply to the variable gain phase shifter 4 is stopped when the value becomes smaller than a predetermined value, power saving can be achieved without causing a communication error or a significant change in sensitivity.

  In the communication device 1 according to the present embodiment, the variable gain phase shifter 4 is configured by one variable gain amplifier 41. However, as shown in the block diagram of FIG. ,..., 41-N, and the power supply to the plurality of variable gain amplifiers 41-1, 41-2,. You may do it.

  The present invention has an effect that power saving can be achieved without causing a communication error or a significant change in sensitivity, and can be applied to a small communication device such as a mobile phone or a PDA.

DESCRIPTION OF SYMBOLS 1 Communication apparatus 2 Antenna 3 Noise sensor part 4 Variable gain phase shift part 5 Adder 6 Tuner 7 Demodulator 8 Controller 41, 41-1, 41-2, ..., 41-N Variable gain amplifier 42 Variable phase shifter

Claims (9)

An antenna for receiving an external radio signal;
A noise sensor unit for acquiring noise;
A variable gain phase shift unit for increasing or decreasing the gain of the output of the noise sensor unit;
An adder that takes a difference between an output signal of the variable gain phase shifter and a radio signal received from the antenna;
A communication device that decreases the gain based on a reception quality index based on an output of the adder, and stops power supply to the variable gain phase shifter when the gain becomes a predetermined value or less. The communication device according to claim 1,
A communication device in which the predetermined value is substantially zero. The communication device according to claim 1 or 2,
A communication device that reduces the gain as the reception quality index is BER and the BER decreases. The communication device according to claim 1 or 2,
The reception quality index is C / N,
A communication device that decreases the gain as the C / N increases. The communication device according to claim 1 or 2,
The reception quality indicator is RSSI;
A communication device that decreases the gain as the RSSI increases. The communication device according to claim 1 or 2,
The reception quality indicator is an AGC control value,
A communication device that decreases the gain as the AGC control value decreases. The communication device according to claim 3 or 4,
The BER and C / N are communication devices output from a demodulator connected to the output of the adder. The communication device according to claim 5 or 6,
The RSSI and the AGC control value are communication devices that are output from a tuner connected to the output of the adder. The communication device according to any one of claims 1 to 8,
The variable gain phase shifter is composed of a plurality of variable gain amplifiers;
A communication device that stops power supply to the plurality of variable gain amplifiers one by one in conjunction with the control for reducing the gain.

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