JP4528607B2 - Mobile radio terminal and receiving circuit - Google Patents

Description

  The present invention relates to a receiving circuit used for a mobile radio terminal such as a mobile phone and used to detect a received power level from a base station.

  2. Description of the Related Art In recent years, a spread spectrum system that is resistant to interference and interference has attracted attention as a communication system applied to a wireless mobile communication system such as a mobile phone. The CDMA (Code Division Multiple Access) method using the spread spectrum communication method is particularly characterized in that a mobile station can smoothly perform a handover that moves between base stations.

  And in order to implement | achieve this smooth hand-over, it is necessary for a mobile station to measure the received power level of the signal from a base station, and to report to a base station regularly (for example, refer patent document 1). The received power level is used as comparison data for base station selection in the mobile station. For these reasons, it is necessary to accurately obtain the received power level.

  However, in the conventional mobile radio terminal, when there is interference power in the channel adjacent to the desired channel, the power out of the desired wave band is attenuated by the baseband channel filter, so that the Carrier RSSI cannot be obtained correctly. .

Further, although the reception unit is intermittently operated during standby, the AGC does not converge well immediately after getting up, and the detected RSSI varies by 1 dB to 2 dB. For this reason, there is a problem that RSSI cannot be obtained accurately in a short time. Long-time measurement can detect RSSI with high accuracy, but it wastes battery power.
Japanese Patent No. 3528727.

  Conventional mobile radio terminals have a problem that Carrier RSSI cannot be obtained correctly. In addition, although the reception unit is intermittently operated during standby, there is a problem that AGC does not converge well in a short time and RSSI cannot be detected accurately.

  The present invention has been made to solve the above-described problem, and an object thereof is to provide a mobile radio terminal and a receiving circuit that can accurately detect a Carrier RSSI without increasing power consumption.

  In order to achieve the above object, the present invention provides an amplifying means for amplifying a received radio signal, a demodulating means for demodulating the radio signal amplified by the amplifying means, and a power level of a demodulation result of the demodulating means. A mobile radio terminal for performing automatic gain control, comprising: a first detecting means for detecting; and a gain control means for controlling the gain of the amplifying means based on the power level detected by the first detecting means. Filter means for extracting a signal in a desired frequency band from the result, second detection means for detecting the power level of the signal extracted by the filter means, power level detected by the second detection means, and a preset reference value And a level correction means for correcting the level fluctuation by adding the difference to the power level detected by the first detection means by automatic gain control.

  As described above, in the present invention, the difference between the power level detected by the second detection means and the preset reference value is added to the power level detected by the first detection means in the automatic gain control loop. Therefore, the level fluctuation is corrected.

  Therefore, according to the present invention, the fluctuation of the power level detected in the automatic gain control loop can be corrected without continuously measuring the received power level until the gain control by the automatic gain control loop converges. Therefore, it is possible to provide a mobile radio terminal capable of accurately measuring the received power level without increasing the power consumption.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a configuration of a reception system of a mobile radio terminal according to an embodiment of the present invention. The mobile radio terminal includes an antenna 1, a reception amplifier 10, a demodulation circuit 11, an A / D converter 12, a channel filter 13, a modem reception unit 14, an AGC control unit 15, and a D / A conversion unit 16. And an address-RSSI conversion unit 17, a power calculation circuit 18, and a Carrier RSSI calculation unit 19.

  The antenna 1 receives a radio signal transmitted from a base station of a mobile communication system (not shown) from the space and outputs it to the reception amplifier 10. The reception amplifier 10 amplifies the reception signal input from the antenna 1 with a gain according to an instruction from the AGC control unit 15 described later. The demodulation circuit 11 obtains a baseband signal obtained by demodulating the radio signal amplified by the reception amplifier 10.

  The A / D converter (A / D) 12 A / D converts the baseband signal and outputs the digital signal obtained thereby to the channel filter 13 and the AGC control unit 15. The channel filter 13 cuts components other than the desired channel from the digital signal, and outputs a component corresponding to the desired channel to the modem receiver 14. The modem receiving unit 14 demodulates data from the digital signal that has passed through the channel filter 13.

The channel filter 13, for example, those conforming to the test prescribed in 3GPP (3 ^rd Generation Partnership Project) standard 25.101 7.5 Adjacent Channel Selectivity. That is, as shown in FIG. 2, even when a W-CDMA (Wideband Code Division Multiple Access) signal is present in a large amount of 33 dB in the adjacent channel N that is 5 MHz away from the desired signal S, this signal can be cut significantly.

  The AGC control unit 15 obtains a reception amplifier control value for controlling the reception amplifier 10 and an AGC address value based on the digital signal obtained by the A / D converter 12. FIG. 3 shows a configuration example of the AGC control unit 15. The AGC control unit 15 includes a power calculation circuit 151, an adder 152, a reference data storage unit 153, an integration circuit 154, and a reception amplifier control unit 155.

  The power calculation circuit 151 squares the digital signal obtained by the A / D converter 12 and converts it into a power value. The adder 152 subtracts the reference value stored in the reference data storage unit 153 from the power value, and outputs the subtraction result to the integration circuit 154. The integration circuit 154 outputs an average value obtained by integrating the subtraction result for a certain time as an AGC address value to the reception amplifier control unit 155 and the address-RSSI conversion unit 17.

  The reception amplifier control unit 155 obtains a reception amplifier control value for setting the output level of the reception amplifier 10 to a desired level from the AGC address value based on the built-in conversion table, and outputs it to the D / A conversion unit 16. . The D / A converter 16 D / A converts the reception amplifier control value to obtain a control voltage for controlling the reception amplifier 10. Then, the gain of the receiving amplifier 10 is controlled by this control voltage.

  The conversion table of the reception amplifier control unit 155 associates the AGC address value (input) with the reception amplifier control value (output) as shown in FIG. 4, for example. In this example, when the AGC address value is “1002”, the reception amplifier control value is “973”, and when the AGC address value is “50”, the reception amplifier control value is “30”. It has become.

  The address-RSSI conversion unit 17 obtains a Pre_RSSI value from the AGC address value output from the AGC control unit 15 based on a built-in conversion table, and outputs the value to the Carrier RSSI calculation unit 19.

The conversion table is, for example, as shown in FIG. When the AGC address value is “1002”, the Pre_RSSI value is −32 [dBm], and when the AGC address value is “50”, the Pre_RSSI value is −127 [dBm]. This table is created based on the following formula (1).

  The power calculation circuit 18 squares the digital signal that has passed through the channel filter 13 and converts it into a power value. This power value is output to the Carrier RSSI calculator 19 as the power average value Pm.

The Carrier RSSI calculation unit 19 obtains a Carrier RSSI value based on the Pre_RSSI value, the power average value Pm, and the following equation (2). The Carrier RSSI value obtained here is notified to the base station through a transmission system (not shown) and used as information when selecting a communicable base station.

FIG. 6 shows a configuration example of the Carrier RSSI calculation unit 19. The Carrier RSSI calculation unit 19 shown in this figure includes a calculation unit 191, an adder 192, a storage unit 193, and an adder 194.
The calculation unit 191 obtains 10Log ₁₀ Pm based on the power average value Pm. The adder 192 subtracts the reference value 10Log ₁₀ Pref stored in the storage unit 193 from 10Log ₁₀ Pm obtained by the arithmetic unit 191 and outputs the subtraction result (10Log ₁₀ (Pm / Pref)) to the adder 194. . The adder 194 adds the Pre_RSSI value and the subtraction result (10Log ₁₀ (Pm / Pref)), and outputs the addition result as a Carrier RSSI value.

  Next, the operation of the mobile radio terminal having the above configuration will be described. Here, in particular, the measurement of the reception power level at the time of intermittent reception will be described. In the example shown in FIG. 7, the reception system shifts from the sleep state to the wake-up state at time t0, and then enters the sleep state again at time t1.

  The AGC control unit 15 obtains an AGC address value based on the digital signal obtained by the A / D converter 12 at time t0, that is, when the wakeup state is entered. The AGC address value is converted into a Pre_RSSI value by the address-RSSI conversion unit 17.

  The Pre_RSSI value has a level fluctuation of 1 dB to 2 dB as shown in FIG. 7 due to an insufficient convergence time of the AGC loop including the reception amplifier 10, the demodulation circuit 11, the A / D converter 12, and the AGC control unit 15.

  On the other hand, the power calculation circuit 18 also obtains the power average value Pm based on the digital signal that has passed through the channel filter 13 at the time t0, that is, at the time of entering the wake-up state. Both the Pre_RSSI value obtained by the AGC control unit 15 and the average power value Pm obtained by the power calculation circuit 18 are output to the Carrier RSSI calculation unit 19.

On the other hand, the Carrier RSSI calculator 19 obtains a correction term 10Log ₁₀ (Pm / Pref) for correcting the level fluctuation based on the power average value Pm and the reference value 10Log ₁₀ Pref. Then, the Carrier RSSI calculation unit 19 adds the correction term 10Log ₁₀ (Pm / Pref) to the Pre_RSSI value to obtain the Carrier RSSI value in which the level fluctuation is corrected.
Eventually, when 100 [ms] elapses from time t0 and time t1 is reached and the reception system is again in the sleep state, the calculation of the Carrier RSSI value is terminated.

  As described above, in the mobile radio terminal having the above-described configuration, the correction term for obtaining the Pre_RSSI value based on the digital signal before passing through the channel filter 13 that suppresses the component of the adjacent channel and correcting the level fluctuation generated in the Pre_RSSI value. Is obtained from the average power value Pm based on the digital signal that has passed through the channel filter 13, and this is added to the Pre_RSSI value to obtain the Carrier RSSI corrected for the level fluctuation.

  Therefore, according to the mobile radio terminal having the above-described configuration, it is possible to correct the level fluctuation occurring in the Pre_RSSI value without performing long-time measurement until the gain control by the AGC loop converges, thereby increasing power consumption. It is possible to detect Carrier RSSI accurately.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. Further, for example, a configuration in which some components are deleted from all the components shown in the embodiment is also conceivable. Furthermore, you may combine suitably the component described in different embodiment.

  For example, in the above-described embodiment, the channel filter 13 is provided in order to suppress the adjacent channel component. However, the present invention can be applied to a configuration that does not include the channel filter 13.

  In that case, the power calculation circuit 18 squares the digital signal output from the A / D converter 12 to obtain the power average value Pm, and outputs this to the Carrier RSSI calculation unit 19. Even with such a configuration, it is possible to correct the level fluctuation occurring in the Pre_RSSI value.

  In the above embodiment, the configuration of the Carrier RSSI calculation unit 19 is shown as a hardware configuration as shown in FIG. 6, but it can also be realized by using a DSP, a CPU, and software.

In the above embodiment, the operation at the time of standby reception has been described as an example. However, the present invention is not limited to this, and can be applied at the time of data communication or a call.
Furthermore, in the above embodiment, the base of the logarithm has been described as “10”, but the present invention is not limited to this, and natural logarithms “e”, “2”, and the like can also be used.
In the above embodiment, the CDMA system has been described as an example. However, the present invention is not limited to this, and can be applied to other communication systems such as a TDMA system and an SDMA system.
In addition, it goes without saying that the present invention can be similarly implemented even if various modifications are made without departing from the gist of the present invention.

The circuit block diagram which shows the structure of one Embodiment of the mobile radio | wireless terminal concerning this invention. The figure for demonstrating the specification of the channel filter of the mobile radio | wireless terminal shown in FIG. The circuit block diagram which shows the structure of the AGC control part of the mobile radio | wireless terminal shown in FIG. The figure for demonstrating the conversion table of the receiving amplifier control part of the mobile radio | wireless terminal shown in FIG. The figure for demonstrating the conversion table of the address-RSSI conversion part of the mobile radio | wireless terminal shown in FIG. The circuit block diagram which shows the structure of the Carrier RSSI calculation part of the mobile radio | wireless terminal shown in FIG. The figure for demonstrating operation | movement of the mobile radio | wireless terminal shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Antenna, 10 ... Reception amplifier, 11 ... Demodulation circuit, 12 ... A / D converter, 13 ... Channel filter, 14 ... Modem receiver, 15 ... AGC control part, 16 ... D / A converter, 17 ... Address -RSSI conversion unit, 18 ... power calculation circuit, 19 ... Carrier RSSI calculation unit, 151 ... power calculation circuit, 152 ... adder, 153 ... reference data storage unit, 154 ... integration circuit, 155 ... reception amplifier control unit, 191 ... Arithmetic unit, 192... Adder, 193... Storage unit, 194.

Claims (6)

Amplifying means for amplifying the received radio signal;
Demodulation means for demodulating the radio signal amplified by the amplification means;
First detection means for detecting the power level of the demodulation result of the demodulation means;
A mobile radio terminal for performing automatic gain control, comprising gain control means for controlling the gain of the amplification means based on the power level detected by the first detection means,
Filter means for extracting a signal of a desired frequency band from the demodulation result;
Second detection means for detecting the power level of the signal extracted by the filter means;
The difference between the reference value which the second detection means is preset power levels detected, and the level correction means for correcting the level variation is added to the power level of the first detecting means is detected by the automatic gain control A mobile radio terminal comprising: Amplifying means for amplifying the received radio signal;
Demodulation means for demodulating the radio signal amplified by the amplification means;
First detection means for detecting the power level of the demodulation result of the demodulation means;
A mobile radio terminal for performing automatic gain control, comprising gain control means for controlling the gain of the amplification means based on the power level detected by the first detection means,
Second detection means for detecting a power level of a demodulation result of the demodulation means;
Level correction means for adding the difference between the power level detected by the second detection means and a preset reference value to the power level detected by the first detection means by the automatic gain control and correcting the level fluctuation; A mobile radio terminal comprising:   The level correction means corrects the level fluctuation by adding a value obtained by subtracting the reference value from the logarithmic value of the power level detected by the second detection means to the power level detected by the first detection means. The mobile radio terminal according to claim 1 or 2, characterized by the above. Amplifying means for amplifying the received radio signal;
Demodulation means for demodulating the radio signal amplified by the amplification means;
First detection means for detecting the power level of the demodulation result of the demodulation means;
A receiving circuit for performing automatic gain control, comprising gain control means for controlling the gain of the amplification means based on the power level detected by the first detection means,
Filter means for extracting a signal of a desired frequency band from the demodulation result;
Second detection means for detecting the power level of the signal extracted by the filter means;
Level correction means for adding the difference between the power level detected by the second detection means and a preset reference value to the power level detected by the first detection means by the automatic gain control and correcting the level fluctuation; A receiving circuit comprising: Amplifying means for amplifying the received radio signal;
Demodulation means for demodulating the radio signal amplified by the amplification means;
First detection means for detecting the power level of the demodulation result of the demodulation means;
A receiving circuit for performing automatic gain control, comprising gain control means for controlling the gain of the amplifying means based on the power level detected by the first detecting means,
Second detection means for detecting a power level of a demodulation result of the demodulation means;
Level correction means for adding the difference between the power level detected by the second detection means and a preset reference value to the power level detected by the first detection means by the automatic gain control and correcting the level fluctuation; A receiving circuit comprising:   The level correction means corrects the level fluctuation by adding a value obtained by subtracting the reference value from the logarithmic value of the power level detected by the second detection means to the power level detected by the first detection means. The receiving circuit according to claim 4, wherein:

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