JP2011176514A - Cellular phone terminal, mobile communication system and lna low gain mode switching control method for use therein - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cellular phone terminal which reduces power consumption while maintaining reception characteristics even if the RSSI is larger than the reception level at which high gain mode switching of LNA occurs when high-speed RXAGC is completed during frequency setting. <P>SOLUTION: The cellular phone terminal includes a low noise-amplifier (an RF device 14) having a mechanism of switching the gain by the reception level from a base station, and is compatible with all communication rates. The cellular phone terminal has a means (a digital signal processor 12) for switching the gain of the low noise-amplifier forcibly to the low gain mode if the received signal intensity signal is larger than the reception level at which high gain mode switching of the low-noise amplifier takes place when the high-speed automatic gain control is completed during frequency setting. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a mobile phone terminal, a mobile communication system, an LNA low gain mode switching control method used therefor, and a program therefor, and more particularly to an LNA (Low Noise Amplifier) having a mechanism capable of performing gain switching according to a reception level in a mobile phone terminal. .

  Since the LNA gain mode switching threshold is constant regardless of the communication rate, a reception level that does not cause deterioration in reception sensitivity even when the communication rate is high is set (for example, see Patent Document 1).

  A general configuration of this LNA is shown in FIG. In FIG. 12, the LNA circuit 30 includes an LNA 31, a bias (Bias) circuit 32, a switch 33, and a logic (Logic) circuit 34.

  The LNA circuit 30 has a high gain mode and a low gain mode. In the high gain mode, the LNA 31 is turned on to amplify the signal and increase the S / N (Signal / Noise) ratio (ratio of signal to noise). . On the contrary, in the low gain mode, the LNA 31 is turned off and a path for bypassing the LNA 31 (path via the switch 33) is provided to output the signal without amplifying it.

  The general LNA shown in FIG. 12 has a high gain mode and a low gain mode as described above. In the high gain mode, the low noise amplifier is turned on to amplify the signal and increase the SN ratio. Conversely, in the low gain mode, the low noise amplifier is turned off and a path for bypassing the low noise amplifier is provided, and the signal is output without being amplified.

  Therefore, when the reception level is sufficiently high, there is an advantage that the current consumption can be reduced by setting the low gain mode and turning off the low noise amplifier. For this reason, in general, when the reception level is large in a mobile phone terminal, the LNA is set to the low gain mode as much as possible to reduce the current consumption. When the reception level is close to the reception sensitivity level, the mode is switched to the high gain mode to improve the SN ratio and improve the reception sensitivity. It is improving.

  However, in the above-mentioned LNA, as shown in FIG. 13, a switching threshold value for switching from the low gain mode to the high gain mode and a switching threshold value for switching from the high gain mode to the low gain mode are provided so that LNA switching does not occur more frequently. Usually there is a threshold.

  For example, when the reception level at the switching threshold value for switching from the low gain mode to the high gain mode is −70 dBm, and the reception level between the switching threshold values for switching from the high gain mode to the low gain mode is −50 dBm, the reception level is −60 dBm. If there is, there is a case of either the low gain mode or the high gain mode, and the same situation occurs between the reception levels (−50 dBm to −70 dBm) at which LNA switching occurs.

  In other words, there is a situation where the current consumption varies depending on the LNA mode while maintaining the same reception level. Here, RXAGC gain (reception automatic gain control gain) refers to the gain of the RFIC (Radio Frequency Integrated Circuit) reception variable amplifier, and the total reception gain is the sum of the LNA gain and the RXAGC gain. .

  For example, when the reception level is −65 dBm, it is assumed that the LNA gain in the high gain mode of the LNA is 15 dB and the RXAGC gain at that time is 35 dB. When the LNA low gain is 0 dB, the total reception gain is the same as that in the LNA high gain mode, and the RXAGC gain at that time is 50 dB.

Japanese Patent Laid-Open No. 2005-223583

  In the above-described LNA, as shown in FIGS. 3 and 4, the same RSSI (Received Signal Strength Indicator) value is obtained because the convergence result of the high-speed RX AGC is different in spite of the same reception environment. However, the LNA gain mode may be different.

  As a result, even when the RSSI value is the same, the current consumption is different between the low gain mode and the high gain mode of the LNA. Recently, there has been a tendency for LNAs to be built into RFICs. At that time, it is common for input / output to be differentiated, and the current consumption is simply doubled compared to LNAs that have only one input / output. It has become. Therefore, the current consumption difference increases depending on whether the LNA is in the low gain mode or the high gain mode, and this situation improvement is required.

  Therefore, an object of the present invention is to solve the above-mentioned problems, and even when RSSI is larger than the reception level at which high gain mode switching of LNA occurs when the high-speed RXAGC performed at the time of frequency setting is completed, the power consumption is maintained while maintaining the reception characteristics. Mobile phone terminal, mobile communication system, LNA low gain mode switching control method used therefor, and a program thereof.

A mobile phone terminal according to the present invention includes a low noise amplifier having a mechanism capable of performing gain switching according to a reception level from a base station, and is a mobile phone terminal corresponding to a communication rate from low speed to high speed,
Provided with means for forcibly switching the gain of the low noise amplifier to the low gain mode when the received signal strength indication signal is larger than the reception level at which the high gain mode switching of the low noise amplifier occurs upon completion of the high-speed reception automatic gain control performed at the frequency setting. Yes.

  A mobile communication system according to the present invention includes the above mobile phone terminal.

The LNA low gain mode switching control method according to the present invention includes a base station and a low noise amplifier having a mechanism capable of performing gain switching according to a reception level from the base station, and is used for a mobile phone terminal corresponding to a communication rate from low speed to high speed. An LNA low gain mode switching control method comprising:
When the mobile phone terminal completes the high-speed reception automatic gain control performed when the frequency is set, and the received signal strength display signal is larger than the reception level at which the high-gain mode switching of the low-noise amplifier occurs, the gain of the low-noise amplifier is forcibly set to the low-gain mode. The process to switch to is executed.

The program according to the present invention includes a base station and a low-noise amplifier having a mechanism capable of switching gains according to a reception level from the base station, and is executed by a central processing unit in a mobile phone terminal that supports communication rates from low speed to high speed. A program to
Includes processing to forcibly switch the gain of the low noise amplifier to low gain mode when the received signal strength indication signal is greater than the reception level at which high gain mode switching of the low noise amplifier occurs at the completion of high-speed reception automatic gain control performed when setting the frequency It is characterized by.

  The present invention is configured and operated as described above, so that consumption is maintained while maintaining reception characteristics even when RSSI is higher than the reception level at which high gain mode switching of LNA occurs when high-speed RXAGC performed at the time of frequency setting is completed. The effect that electric power can be reduced is obtained.

It is a block diagram which shows the structural example of the mobile telephone terminal by the 1st Embodiment of this invention. It is a block diagram which shows the structure of RF apparatus of FIG. It is a figure which shows the example finally converged to the LNA low gain mode by the general high-speed RXAGC implemented at the time of the frequency switch in the 1st Embodiment of this invention. It is a figure which shows the example finally converged to LNA high gain mode by the general high-speed RXAGC implemented at the time of the frequency switch in the 1st Embodiment of this invention. The figure which shows the example which switches the gain mode of LNA to low gain mode compulsorily when the RSSI measurement result at the time of completion of high-speed RXAGC is larger than RSSI which LNA high gain mode switching generate | occur | produces in the 1st Embodiment of this invention. is there. It is a flowchart which shows the control procedure by the 1st Embodiment of this invention. It is a flowchart which shows the control procedure by the 2nd Embodiment of this invention. It is a flowchart which shows the control procedure by the 3rd Embodiment of this invention. It is a figure which shows the example of switching of LNA in the 3rd Embodiment of this invention. It is a flowchart which shows the control procedure by the 4th Embodiment of this invention. It is a figure which shows how to obtain | require SIR in the 4th Example of this invention. It is a block diagram which shows the general structure of LNA relevant to this invention. It is a figure which shows the example of switching of LNA relevant to this invention.

  Next, embodiments of the present invention will be described with reference to the drawings. First, an outline of an LNA (Low Noise Amplifier) low gain mode switching control method according to the present invention will be described.

  The LNA low gain mode switching control method according to the present invention includes an LNA having a mechanism capable of performing gain switching according to a reception level, and is compulsory when the reception level is higher than a reception level at which high gain mode switching of the LNA occurs. The control is performed to switch the LNA to low gain.

  In other words, in order to solve the above-described problem, the present invention switches the LNA high gain mode when RSSI (Received Signal Strength Indicator) is completed when high-speed RXAGC (reception automatic gain control) performed at the time of frequency setting is completed. If the received signal level is larger than the received level, the LNA gain is forcibly switched to the low gain mode to provide a method that can further reduce power consumption.

  The general LNA shown in FIG. 12 has a high gain mode and a low gain mode as described above. In the high gain mode, a low noise amplifier is turned on to amplify a signal, and an SN (Signal / Noise) ratio (signal to noise). The ratio). Conversely, in the low gain mode, the low noise amplifier is turned off and a path for bypassing the low noise amplifier is provided, and the signal is output without being amplified.

  Therefore, when the reception level is sufficiently high, there is an advantage that the current consumption can be reduced by setting the low gain mode and turning off the low noise amplifier. For this reason, in general, when the reception level is large in a mobile phone terminal, the LNA is set to the low gain mode as much as possible to reduce the current consumption. When the reception level is close to the reception sensitivity level, the mode is switched to the high gain mode to improve the SN ratio and improve the reception sensitivity. It is improving.

  However, in this LNA, as shown in FIG. 13, a switching threshold value for switching from the low gain mode to the high gain mode and a switching threshold value for switching from the high gain mode to the low gain mode are provided, so that more frequent LNA switching does not occur. There is a threshold.

  For example, when the reception level at the switching threshold value for switching from the low gain mode to the high gain mode is −70 dBm, and the reception level between the switching threshold values for switching from the high gain mode to the low gain mode is −50 dBm, the reception level is −60 dBm. If there is, there is a case of either the low gain mode or the high gain mode, and the same situation occurs between the reception levels (−50 dBm to −70 dBm) at which LNA switching occurs.

  In other words, there is a situation where the current consumption varies depending on the LNA mode while maintaining the same reception level. Here, RXAGC gain (reception automatic gain control gain) refers to the gain of the RFIC (Radio Frequency Integrated Circuit) reception variable amplifier, and the total reception gain is the sum of the LNA gain and the RXAGC gain. .

  For example, when the reception level is −65 dBm, it is assumed that the LNA gain in the high gain mode of the LNA is 15 dB and the RXAGC gain at that time is 35 dB. When the LNA low gain is 0 dB, the total reception gain is the same as that in the LNA high gain mode, and the RXAGC gain at that time is 50 dB.

  In order to solve the above problem, in the present invention, when high-speed RXAGC performed at the time of frequency setting is completed, the reception level is larger than the reception level at which high-gain mode switching of LNA occurs (= RXAGC gain is switched to LNA high-gain mode) If it is smaller than the RXAGC gain), the LNA gain is forcibly switched to the low gain mode, so that the power consumption can be reduced while maintaining the reception characteristics at the intermediate potential level.

  FIG. 1 is a block diagram showing a configuration example of a mobile phone terminal according to the first embodiment of the present invention. In FIG. 1, a mobile phone terminal according to the first embodiment of the present invention includes a CPU (Central Processing Unit) device 11, a digital signal processing device 12 under the basic control, an analog signal processing device 13, An RF (Radio Frequency) device 14, a memory device 15, a power supply device 16, a battery 17, and an antenna 18 are included.

  The CPU device 11 controls the digital signal processing device 12, the analog signal processing device 13, the RF device 14, the memory device 15, the power supply device 16, and exchanges data with the digital signal processing device 12.

  The RF device 14 performs modulation / demodulation of the radio signal, and the analog signal processing device 13 performs AD (analog / digital) conversion of the signal from the RF device 14 and sends the AD converted signal to the digital signal processing device 12. The signal from the signal processing device 12 is DA (digital / analog) converted, and the DA converted signal is sent to the RF device 14.

  The digital signal processing device 12 performs digital signal processing on the signal from the analog signal processing device 13, decodes the signal, and sends the decoded signal to the CPU device 11.

  Also, the digital signal processing device 12 measures the RSSI level and sends an RXAGC gain control signal and an LNA mode switching signal to the RF device 14 in accordance with the measured value.

  Further, the digital signal processing device 12 performs power control of the transmission signal, performs SIR (Signal to Interference power Ratio) measurement, and performs frequency setting control.

  Control information and the like are written in the memory device 15, and the CPU device 11 performs reading and writing according to the control information. The memory device 15 stores LNA mode switching threshold data. Further, the memory device 15 stores a program for the CPU device 11 to control and a program executed by the digital signal processing device 12.

  The power supply device 16 supplies power to the CPU device 11, the digital signal processing device 12, the analog signal processing device 13, the RF device 14, and the memory device 15 in accordance with control from the CPU device 11. The battery 17 supplies a voltage to the entire device via the power supply device 16. The antenna 18 receives a signal from a base station (not shown) and transmits a signal from the mobile phone terminal to the base station.

  FIG. 2 is a block diagram showing the configuration of the RF device 14 of FIG. 2, the RF device 14 includes an antenna switch (ANTSW) 141, a duplexer 142, an LNA 143, a BPF (Band Path Filter) 144, an RFIC 145, a BPF 146, a PA 147, and an isolator 148. .

  The antenna switch (ANTSW) 141 normally switches the antenna 18 to be used. The duplexer 142 is a filter that separates a transmission signal and a reception signal. The LNA 143 can amplify a signal while suppressing noise as much as possible, and can be switched between a high gain mode and a low gain mode.

  The BPF 144 attenuates signals other than the received signal. The RFIC 145 includes a signal modulation / demodulation circuit, a transmission / reception variable gain amplifier, a baseband filter, an amplifier, and a PLL (Phase Locked Loop) synthesizer. The BPF 146 attenuates signals other than the transmission signal. The PA 147 is an amplifier that can be amplified to a high power. The isolator 148 does not reverse the high power signal.

  The LNA low gain mode switching control method according to the first embodiment of the present invention will be described with reference to FIGS. Hereinafter, how to obtain RSSI and LNA gain will be shown as an example. In this example, a case of WCDMA (Wideband Code Division Multiple Access) will be described.

In the case of WCDMA, the received signal is demodulated and then divided into an I signal and a Q signal. First, instantaneous power is obtained (RSSI calculation # 1). This instantaneous power is
RX_Level (n) = I (n) ² + Q (n) ²
(N = 0 to N)
It is calculated by the formula. N is an arbitrary number of samples.

Next, the average instantaneous power is obtained (RSSI calculation # 2). This average instantaneous power is
RX_Level2 = 1 / N · ΣRX_Level (n)
It is calculated by the formula. Note that Σ is the sum of n = 0 to N.

Subsequently, the average instantaneous power value is converted by dB (RSSI calculation # 3). The dB conversion is
RX_Level_dB = 10 Log (RX_Level2)
It is done with the formula.

  Further, a known level (for example, a signal of −60 dBm) is input from the antenna 18, and the digital signal processing device 12 calculates RSSI calculation # 1 to RSSI calculation # 3 (RSSI calculation # 4).

In the digital signal processing device 12, when the LNA 143 is in the high gain mode,
RX_Level correction value = −60 dBm−RX_Level_dB
+ LNA_GAIN + RFIC_GAIN
When the LNA 143 is in the low gain mode,
RX_Level correction value = −60 dBm−RX_Level_dB + RFIC_GAIN
(RSSI calculation # 5).

  LNA_GAIN, which is the gain of LNA 143, is the difference between RSSI in the low gain mode and RSSI in the high gain mode in RSSI calculation # 5, RFIC_GAIN is the gain of the receiving variable amplifier of RFIC 145, and is set by digital signal processing device 12 Therefore, it is a known value.

For example, if the value of RX_Level_dB when the LNA 143 is in the high gain mode is 10 dBm, LNA_GAIN = 15 dB, and RFIC_GAIN = 30 dB, the RX_Level correction value is −25 dB. With the above,
RSSI = RX_Level_dB-LNA_GAIN
-RFIC_GAIN-RX_Level correction value (RSSI calculation # 6).

Further, if the value of RX_Level_dB when the LNA is in the low gain mode is 10 dBm and RFIC_GAIN = 45 dB, the RX_Level correction value is −25 dB. With the above,
RSSI = RX_Level_dB-RFIC_GAIN
-RX_Level correction value (RSSI calculation # 7).

  Next, a method for switching the LNA 143 from the low gain mode to the high gain mode will be described. Initially, the LNA 143 performs RSSI measurement (RSSI calculation # 8) in the low gain mode.

  At that time, for example, when RSSI = −70 dBm in a state where the high gain mode switching threshold (HIGHGAIN_TH) = − 70 dBm is set, the digital signal processing device 12 detects that the high gain mode switching threshold ≧ RSSI, A signal for switching the LNA 143 from the low gain to the high gain mode is sent. The LNA 143 switches from the low gain to the high gain mode by this signal. The subsequent RSSI measurement method is performed by RSSI calculation # 6.

  Similarly, the switching method of the LNA 143 from the high gain mode to the low gain mode is, for example, when the low gain mode switching threshold (LOWGAIN_TH) = − 50 dBm is set, and when RSSI = −50 dBm, the digital signal processing device 12 After detecting that the mode switching threshold ≦ RSSI, a signal for switching the LNA 143 from the high gain to the low gain mode is sent. The LNA 143 is switched from the high gain mode to the low gain mode by this signal. The subsequent RSSI measurement method is performed by RSSI calculation # 7.

  Next, an example of high-speed RXAGC performed at the time of frequency setting is shown. This time, the case of WCDMA is shown as an example. In the case of WCDMA, RSSI measurement and RXAGC are usually performed in units of 1 slot (about 667 μs).

  However, at the time of frequency switching, the RSSI of the switching destination frequency is unknown and the digital signal processing device 12 needs to reach a desired level at high speed in order to start normal reception operation.

  For that purpose, it is necessary to perform RXAGC at high speed. The unit of RSSI measurement and RXAGC is shortened to, for example, 30 μs, and is performed about 10 times, and then the conventional RSSI measurement and RXAGC in one slot unit are performed. Generally, a switching method is taken, and normal reception operation and normal communication are performed at the same time. That is, high-speed RXAGC is for stabilizing RXAGC at high speed, and does not perform normal communication.

  FIG. 3 shows an example of a general high speed RXAGC implemented at the time of frequency switching and finally converged to the LNA low gain mode. Similarly, FIG. 4 shows an example in which the general high-speed RXAGC implemented at the time of frequency switching finally converges to the LNA high gain mode.

  The LNA gain mode that converges in FIGS. 3 and 4 is different for the same RSSI because the RSSI measurement time is short, and an error occurs in the RSSI measurement and RXAGC determined based on the RSSI measurement. In addition, when the RSSI variation is large in time units, the same result as described above is obtained.

  FIG. 5 is a diagram illustrating an example in which the LNA gain mode is forcibly switched to the low gain mode when the RSSI measurement result at the completion of the high-speed RXAGC is larger than the RSSI in which the LNA high gain mode switching occurs. This shows the high speed RXAGC applied in the present invention.

  FIG. 6 is a flowchart showing a control procedure according to the first embodiment of the present invention. With reference to these FIG. 1, FIG. 2, and FIG. 6, the procedure only relating to the present invention will be described based on the above-mentioned method of obtaining the RSSI and the relationship between the LNA switching from the low gain mode to the high gain mode. In this example, WCDMA, which is a communication method approved by 3GPP (3rd Generation Partnership Project), is used. Note that the control procedure shown in FIG. 6 can also be realized by the CPU device 11 executing the program of the memory device 15.

  First, the CPU device 11 instructs the digital signal processing device 12 to set the frequency. The digital signal processing device 12 sets the frequency in the RFIC 145 of the RF device 14 by this command (step S1 in FIG. 6).

  Next, the CPU device 11 sets the LNA high gain mode switching threshold value (HIGHGAIN_TH) and the LNA low gain mode switching threshold value (LOWGAIN_TH) read from the memory device 15 in the digital signal processing device 12. The digital signal processing device 12 sets the low gain mode in the LNA 143 of the RF device 14 as an initial setting (step S2 in FIG. 6). For example, LNA high gain mode switching threshold (HIGHGAIN_TH) = − 70 dBm, and LNA low gain mode switching threshold (LOWGAIN_TH) = − 50 dBm.

  Next, the digital signal processing device 12 starts high-speed RXAGC and RSSI measurement, starts gain control on the received signal 10 times, for example, in 30 μs units, and simultaneously performs RSSI measurement in the same units. This is performed (step S3 in FIG. 6). At this time, RSSI measured at the 10th time is set to −65 dBm.

The digital signal processing device 12 compares the RSSI and the HIGHGAIN_TH + POWER_OFFSET value (step S4 in FIG. 6). Here, the unit of POWER_OFFSET is dB, for example, 2 dB.
RSSI (-65 dBm)
≧ HIGHGAIN_TH + POWER_OFFSET
(−70 dBm + 2 dB = −68 dB)
Therefore, the digital signal processing device 12 forcibly switches the LNA 143 to the low gain mode (step S5 in FIG. 6).

  If the RSSI measured at the 10th time is −72 dBm, that is, RSSI <HIGHGAIN_TH + POWER_OFFSET, the process of step S5 is not performed.

  In order to shift to normal RXAGC, the digital signal processing device 12 switches the gain control to the received signal and RSSI measurement in units of one slot (667 μs) with respect to the RF device 13 (step S6 in FIG. 6).

  FIG. 7 is a flowchart showing a control procedure according to the second embodiment of the present invention. The cellular phone terminal according to the second embodiment of the present invention has the same configuration as the cellular phone terminal according to the first embodiment of the present invention shown in FIGS.

  The second embodiment of the present invention is that, at the time of frequency setting in the compressed mode (compressed mode), even if the RSSI is equal to or higher than the threshold after the high-speed RX AGC, the mode is not forcibly switched to the LNA low gain mode. This is different from the above embodiment.

  Here, the compressed mode is to increase the transmission rate of a specific portion, thereby providing a section where data transmission is not performed (hereinafter referred to as GAP), and the mobile terminal performs RSSI measurement and the like by switching the reception frequency in that section. Say that.

  This compressed mode is performed when performing a series of synchronization establishment processes such as cell search in carriers of different frequencies while maintaining the current call in inter-frequency handover. At this time, if the time required for establishing synchronization becomes longer, it is necessary to provide more GAP, that is, the compression mode time becomes longer.

  In the compressed mode, there is also a report that the communication quality is deteriorated, and in order to avoid the influence as much as possible, a device for shortening the time required for establishing synchronization is required. For this reason, the time of the high-speed RXAGC ( Frequency) reduction is required. In such a situation, forcibly switching to the LNA low gain mode may have side effects such as communication quality degradation, so this embodiment is necessary.

  Hereinafter, the control procedure according to the second embodiment of the present invention will be described with reference to FIG. 1, FIG. 2, and FIG. The control procedure shown in FIG. 7 can also be realized by the CPU device 11 executing the program of the memory device 15.

  The CPU device 11 instructs the digital signal processing device 12 to set the frequency. The digital signal processing device 12 sets the frequency in the RFIC 145 of the RF device 14 by this command (step S11 in FIG. 7).

  Next, the CPU device 11 sets the LNA high gain mode switching threshold value (HIGHGAIN_TH) and the LNA low gain mode switching threshold value (LOWGAIN_TH) read from the memory device 15 in the digital signal processing device 12. The digital signal processing device 12 sets the low gain mode in the LNA 143 of the RF device 14 as an initial setting (step S12 in FIG. 7). For example, LNA high gain mode switching threshold (HIGHGAIN_TH) = − 70 dBm, and LNA low gain mode switching threshold (LOWGAIN_TH) = − 50 dBm.

  The digital signal processing device 12 starts high-speed RXAGC and RSSI measurement, starts gain control for the received signal, for example, 10 times in units of 30 μs, and simultaneously performs RSSI measurement in the same units (see FIG. 7 step S13).

  The CPU device 11 confirms whether the current compression mode is set (step S14 in FIG. 7). If not in the compressed mode, the RSSI measured at the 10th time is set to −65 dBm.

The digital signal processing device 12 compares the RSSI and the HIGHGAIN_TH + POWER_OFFSET value (step S15 in FIG. 7). If it is in the compressed mode, the process of step S15 and the following process of step S16 are not performed.
RSSI (-65 dBm)
≧ HIGHGAIN_TH + POWER_OFFSET
(−70 dBm + 2 dB = −68 dB)
Therefore, the digital signal processing device 12 forcibly switches the LNA 143 to the low gain mode (step S16 in FIG. 7). If the RSSI measured at the 10th time is −72 dBm, that is, RSSI <HIGHGAIN_TH + POWER_OFFSET, the process of step S16 is not performed.

  In order to shift to normal RXAGC, the digital signal processing device 12 switches the gain control to the received signal and RSSI measurement in units of one slot (667 μs) with respect to the RF device 14 (step S17 in FIG. 7).

  FIG. 8 is a flowchart showing a control procedure according to the third embodiment of the present invention. The cellular phone terminal according to the third embodiment of the present invention has the same configuration as the cellular phone terminal according to the first embodiment of the present invention shown in FIGS.

  According to the third embodiment of the present invention, data CH [DPDCH (Dedicated Physical Data Channel), DPCCH (Dedicated Physical Control Channel)] for performing voice and data communication has a low communication rate of 12.2 kbps. Sometimes, when the RSSI is equal to or greater than the LNA high gain mode switching threshold, the mode is forcibly switched to the LNA low gain mode.

  The third embodiment of the present invention also differs from the above embodiment in that switching is performed at the slot boundary of normal RXAGC (one slot unit) during communication. The reason for forcibly switching to the LNA low gain mode is limited to the low rate when the LNA is frequently and periodically switched between the high gain mode and the low gain mode during communication as shown in FIG. This is because data is lost transiently at a specific location, and at a high rate of 384 kbps or HSDPA (High Speed Downlink Access), the lost data cannot be repaired by digital signal processing, and communication quality is degraded. .

  For this reason, it is necessary to apply the present embodiment only at a low rate of 12.2 kbps, that is, a high spreading factor and a high repair capability even if a little data is lost.

  Hereinafter, the control procedure according to the third embodiment of the present invention will be described with reference to FIG. 1, FIG. 2, and FIG. The control procedure shown in FIG. 8 can also be realized by the CPU device 11 executing the program of the memory device 15.

  The CPU device 11 instructs the digital signal processing device 12 to open the data CH at a certain communication rate, for example, 12.2 kbps, for voice and data communication (step S21 in FIG. 8).

  The digital signal processing device 12 starts communication using the data CH, starts gain control for the reception signal and power control for the transmission signal in units of one slot (667 μs) for the RF device 14, and simultaneously RSSI measurement is performed for one slot (step S22 in FIG. 8).

  The digital signal processing device 12 compares the current communication rate (CURRENT_RATE) with the limit communication rate (LIMIT_RATE) for which the LNA low gain mode is possible (step S23 in FIG. 8). The limit communication rate (LIMIT_RATE) for which the LNA low gain mode can be compulsorily read is read from the memory device 15.

  For example, assuming that the current communication rate is 12.2 kbps or higher when the current communication rate is 30 kbps, that is, if the limit communication rate (LIMIT_RATE) (30 kbps) ≧ current communication rate (CURRENT_RATE) (12.2 kbps), the digital signal processing device 12 Compares RSSI with HIGHGAIN_TH + POWER_OFFSET value (step S24 in FIG. 8).

  When RSSI ≧ HIGHGAIN_TH + POWER_OFFSET, the digital signal processing device 12 forcibly switches the LNA 143 to the low gain mode and returns to the processing of step S22 (step S25 in FIG. 8).

  In the process of step S23, when the limit communication rate (LIMIT_RATE) for which the LNA low gain mode can be forcibly is smaller than the current communication rate (CURRENT_RATE), that is, when the limit communication rate (LIMIT_RATE) <the current communication rate (CURRENT_RATE). The process returns to step S22 without passing through step S24.

  If RSSI <HIGHGAIN_TH + POWER_OFFSET in the process of step S24, the process returns to step S22 without passing through the process of step S25. Thereafter, the same control as described above is performed until a data CH close command is issued.

  FIG. 10 is a flowchart showing a control procedure according to the fourth embodiment of the present invention. The cellular phone terminal according to the fourth embodiment of the present invention has the same configuration as the cellular phone terminal according to the first embodiment of the present invention shown in FIGS.

  The fourth embodiment of the present invention is different from the above-described embodiment in that when the SIR is good and the RSSI is equal to or higher than the LNA high gain mode switching threshold, the LNA low gain mode is forcibly switched.

  Forcibly switching to the LNA low gain mode is limited to when the SIR is good, as shown in FIG. 9, when the LNA is frequently and periodically switched between the high gain mode and the low gain mode during communication, Since data is lost at a specific location in a transient manner, there is a possibility that communication quality may be deteriorated because the lost data cannot be completely restored by digital signal processing in a situation where the SIR deteriorates in a fading environment or the like. It is. For this reason, the minimum required SIR is SIR_STANDARD, and this embodiment is applied only when the SIR_STANDARD is more than that.

  First, how to obtain SIR is shown. In the case of WCDMA, the received signal is demodulated and divided into an I signal and a Q signal. Since the I signal and the Q signal are orthogonal to each other, symbol points are formed on the complex plane. It is desirable that symbol points are gathered at one point, but in reality, the point is widened due to the influence of interference waves. This is shown in FIG.

  The strength up to the ideal symbol point is called RSCP (Received Signal Code Power), which is the power of the signal after despreading. The intensity of spread (dispersion of symbol points) is called ISCP [Interference Signal Code Power: Interference wave (also called interference wave) signal average power], and the difference between symbol points before despreading and symbol points after despreading I can say that.

And SIR is derived | led-out by ratio of RSCP and ISCP. That is,
SIR = RSCP ÷ ISCP
Thus, the larger the interference wave, the smaller the value.

  Further, Ec ÷ No (= RSCP ÷ RSSI), which is a ratio of desired signal energy per bit to noise, may be used instead of SIR by RSSI and RSCP. All of this processing is performed by the digital signal processing device 12.

  Hereinafter, a control procedure according to the fourth embodiment of the present invention will be described with reference to FIG. 1, FIG. 2, and FIG. The control procedure shown in FIG. 10 can also be realized by the CPU device 11 executing the program of the memory device 15.

  The CPU device 11 instructs the digital signal processing device 12 to open the data CH at a certain communication rate, for example, 12.2 kbps in order to perform voice and data communication (step S31 in FIG. 10).

  The digital signal processing device 12 starts communication using the data CH, starts gain control for the reception signal and power control for the transmission signal in units of one slot (667 μs) for the RF device 14, and simultaneously RSSI measurement and SIR measurement are performed for one slot (step S32 in FIG. 10).

  The digital signal processing device 12 forcibly compares the current communication rate with the limit communication rate at which the LNA low gain mode is possible (step S33 in FIG. 8).

  In the case of LIMIT_RATE ≧ CURRENT_RATE, the digital signal processing device 12 compares whether or not the measurement SIR is greater than or equal to the reference SIR_STANDARD (step S34 in FIG. 10).

  When the measurement SIR is equal to or higher than the reference SIR_STANDARD, the digital signal processing device 12 compares the RSSI with the HIGHGAIN_TH + POWER_OFFSET value (step S35 in FIG. 10).

  When RSSI ≧ HIGHGAIN_TH + POWER_OFFSET, the digital signal processing device 12 forcibly switches the LNA 143 to the low gain mode and returns to the processing of step S32 (step S36 in FIG. 10). If LIMIT_RATE <CURRENT_RATE in the process of step S33, the process returns to the process of step S32 without performing the process of step S34.

  If the measurement SIR is less than the reference SIR_STANDARD in the process of step S34, the process returns to the process of step S32 without passing through the process of step S35.

  If RSSI <HIGHGAIN_TH + POWER_OFFSET in the process of step S35, the process returns to the process of step S32 without performing the process of step S36. Thereafter, the same control as described above is performed until a data CH close command is issued.

  As described above, in the present invention, when the high speed RXAGC performed at the time of frequency setting is completed and the RSSI is larger than the reception level at which the LNA high gain mode switching occurs, the LNA gain is forcibly switched to the low gain mode, thereby improving the reception characteristics. Power consumption can be reduced while maintaining.

  Further, in the present invention, even when the RSSI at the completion of the high speed RXAGC performed at the time of frequency setting is larger than the reception level at which the LNA high gain mode switching occurs, the LNA gain is forcibly switched to the low gain mode in the compress mode. Therefore, it is possible to prevent deterioration of reception characteristics at different frequencies.

  Furthermore, in the present invention, if the RSSI is larger than the reception level at which switching of the LNA high gain mode occurs if the communication rate is low, the LNA gain is forcibly switched to the low gain mode at the slot boundary. The power consumption can be reduced while maintaining the reception characteristics.

  Furthermore, in the present invention, when the RSSI is larger than the reception level at which switching of the LNA high gain mode occurs in an environment where the SIR value is good, the LNA gain is forcibly switched to the low gain mode at the slot boundary even in the communication state. As a result, power consumption can be reduced while maintaining reception characteristics.

11 CPU device
12 Digital signal processor
13 Analog signal processor
14 RF equipment
15 Memory device
16 Power supply
17 battery
18 Antenna
141 Antenna switch
142 Duplexer
143 LNA
144,146 BPF
145 RFIC
147 PA
148 Isolator

Claims (10)

A mobile phone terminal that includes a low-noise amplifier with a mechanism that allows gain switching according to the reception level from the base station, and that supports communication rates from low speed to high speed,
Having a means to forcibly switch the gain of the low-noise amplifier to the low-gain mode when the received signal strength indication signal is larger than the reception level at which the high-gain mode switching of the low-noise amplifier occurs when the high-speed reception automatic gain control performed when setting the frequency is completed A mobile phone terminal characterized by.   By increasing the transmission rate of the specific part, a section in which data transmission is not performed is provided, and in the compressed mode in which at least the reception signal strength display signal is measured by switching the reception frequency in the section, the high-speed reception automatic gain 2. The control of forcibly switching the gain of the low noise amplifier to a low gain mode when the received signal strength display signal is larger than a reception level at which switching of the high gain mode of the low noise amplifier occurs when the control is completed. 1. The mobile phone terminal according to 1.   The low-noise amplifier gain is forcibly switched to a low-gain mode if the received signal strength display signal is larger than a reception level at which a high-gain mode switching of the low-noise amplifier occurs when the communication rate is low. The cellular phone terminal according to claim 1 or 2.   When the SIR (Signal to Interference power Ratio) is good even in the communication state, the gain of the low noise amplifier is forcibly set to the low gain mode if the received signal strength display signal is larger than the reception level at which the high gain mode switching of the low noise amplifier occurs. The mobile phone terminal according to any one of claims 1 to 3, wherein the mobile phone terminal is switched to.   A mobile communication system comprising the mobile phone terminal according to any one of claims 1 to 4. An LNA low gain mode switching control method used for a mobile phone terminal that includes a base station and a low noise amplifier having a mechanism capable of performing gain switching according to a reception level from the base station, and supports a communication rate from low speed to high speed,
When the mobile phone terminal completes the high-speed reception automatic gain control performed when the frequency is set, and the received signal strength display signal is larger than the reception level at which the high-gain mode switching of the low-noise amplifier occurs, the gain of the low-noise amplifier is forcibly set to the low-gain mode. An LNA low gain mode switching control method characterized by executing a process of switching to   In the compressed mode, the mobile phone terminal provides a section in which data transmission is not performed by increasing the transmission rate of the specific part, and at least measures the received signal strength display signal by switching the reception frequency in the section. When the high-speed reception automatic gain control is completed, forcibly switching the low-noise amplifier gain to the low-gain mode when the received signal strength display signal is larger than the reception level at which the high-noise mode switching of the low-noise amplifier occurs. The LNA low gain mode switching control method according to claim 6.   When the mobile phone terminal is at a low rate even in a communication state, if the received signal strength indication signal is larger than the reception level at which the high gain mode switching of the low noise amplifier occurs, the gain of the low noise amplifier is forcibly switched to the low gain mode. 8. The LNA low gain mode switching control method according to claim 6 or 7, wherein:   When the mobile phone terminal has a good signal-to-interference power ratio (SIR) even in a communication state, the gain of the low-noise amplifier is higher if the received signal strength display signal is larger than the reception level at which high-gain mode switching of the low-noise amplifier occurs. The LNA low gain mode switching control method according to any one of claims 6 to 8, wherein the LNA is forcibly switched to a low gain mode. A program executed by a central processing unit in a mobile phone terminal corresponding to a communication rate from a low speed to a high speed, including a base station and a low noise amplifier having a mechanism capable of switching gain according to a reception level from the base station,
Includes processing to forcibly switch the gain of the low noise amplifier to low gain mode when the received signal strength indication signal is greater than the reception level at which high gain mode switching of the low noise amplifier occurs at the completion of high-speed reception automatic gain control performed when setting the frequency A program characterized by

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