JP4675277B2 - Radio receiving method and radio receiving apparatus - Google Patents

Description

  The present invention relates to a radio reception method in a radio terminal device such as a mobile phone, a PDA (Personal Digital Assistant), and a radio card terminal, and a radio reception apparatus that implements the radio reception method.

  For example, the frequency in the 800 MHz band mainly used in mobile phones is assigned to the slices sequentially in order to follow the increase in users. For this reason, in the future, third-generation mobile phones adopting the mainstay CDMA system will require a wide frequency bandwidth, and in the current state of being fragmented, it is expected that a band that cannot be used will be generated even if it is allocated. The

  In recent years, therefore, it has been necessary to actively develop a fundamental review of frequency allocation that is not confined to conventional ideas. Therefore, prior to this review, the Ministry of Internal Affairs and Communications presented a basic concept on frequency reorganization. A frequency restructuring policy has been formulated.

  According to this reorganization policy, since the operation at the newly allocated frequency will start from the autumn of 2006, until the full transition to 2012, the previously allocated frequency and the newly allocated frequency will start. Will coexist with the frequency assigned to.

  At the time when the new allocation and the old allocation coexist, for example, there is an area where the downlink frequency band by the old allocation for a certain carrier and the uplink frequency band by the new allocation for another carrier are very adjacent. Will exist.

  Here, the reception (Rx) filter in the mobile phone that receives the downlink frequency band has, for example, as shown in FIG. 16, a pass characteristic with a wide pass bandwidth that sufficiently covers the downlink frequency band (desired reception band). Have. Therefore, when there is an upstream frequency band (transmission frequency band of another system) of a different communication carrier adjacent to the desired reception band, the transmission frequency band of the other system indicated by hatching in this Rx filter. It is assumed that the amount of attenuation in the high frequency part of this can be obtained only at most about 1 dB. FIG. 16 shows a case where the transmission frequency band of the other system is adjacent to the lower limit frequency side of the desired reception band.

  As described above, in the case of a mobile phone having a low noise amplifier (LNA) having an interference characteristic as shown in FIG. 17 to be described later if a sufficient attenuation amount cannot be obtained with respect to the transmission frequency band of another adjacent system. For example, when transmitted from a mobile phone of another system at 24 dBm at a location 1 m away, a mobile phone having a desired reception band adjacent to the transmission frequency band is subjected to sensitivity suppression of 14 dB, for example.

  This sensitivity suppression will be described in more detail.

で表される。ここで、ｄは電波の発信源からの距離（ｍ）、ｆは周波数（Ｈｚ）である。したがって、８００ＭＨｚの電波が２４ｄＢｍで発信されると、１ｍ離れたところの電波強度は、

となる。すなわち、１ｍ離れた場所では、−６．５ｄＢｍの妨害を受けることになる。 The attenuation of radio waves in free space is

It is represented by Here, d is a distance (m) from a radio wave transmission source, and f is a frequency (Hz). Therefore, when an 800 MHz radio wave is transmitted at 24 dBm, the radio field intensity at a distance of 1 m is

It becomes. That is, at a place 1 m away, the interference is −6.5 dBm.

  Here, the reception sensitivity of the mobile phone has a relationship as shown in FIG. 17, for example, with respect to the level of the interference wave (800 MHz). In FIG. 17, the vertical axis represents reception sensitivity (dBm), and the horizontal axis represents interference wave level (dBm). As is clear from FIG. 17, the reception sensitivity without interference is −110 dBm, whereas the reception sensitivity when receiving interference of −6.5 dBm is −96 dBm, and the sensitivity is suppressed by 14 dB. Become.

  The effect of this suppression of reception sensitivity is that both mobile phones that perform power control with the base station that keeps the relationship between transmission power and reception power constant are weak because the transmission power increases when reception power is low. When it is in an electric field, it appears prominently, and there is a possibility that the receivable range of a mobile phone having a desired reception band may be extremely narrowed.

  As a solution to such a problem, for example, a high frequency input of a strong electric field is detected using a breakdown phenomenon of a transistor constituting a low noise amplifier of a receiving circuit, and a front stage of the low noise amplifier is based on the detection result. 2. Description of the Related Art A wireless receiver is known that attenuates adjacent interfering waves by controlling the pass characteristics of a variable filter provided in (see, for example, Patent Document 1).

JP 2002-164804 A

  However, in the wireless reception device disclosed in Patent Document 1 described above, the variable filter is controlled only when the intensity of the adjacent interference wave exceeds a threshold value and the transistor causes a breakdown phenomenon. If the level of the adjacent interference wave is equal to or lower than the threshold value, the adjacent interference wave cannot be attenuated and sensitivity is suppressed.

  In addition, even if the decrease in reception sensitivity is more affected by the insertion loss of the variable filter than the suppression of sensitivity due to adjacent interference noise, the insertion loss is increased unnecessarily because the pass characteristics of the variable filter are controlled. May cause a decrease in sensitivity.

  Instead of using the breakdown phenomenon of the transistor, it is also conceivable to control the variable filter using RSSI (Received Signal Strength Indicator) representing the received electric field strength. However, this RSSI frequently fluctuates according to changes in the distance from the base station, the surrounding environment, and the like, and even when the RSSI is high to some extent, it may have received adjacent interference waves, so only RSSI is used. When the variable filter is controlled, accurate control cannot be performed.

  Therefore, an object of the present invention made in view of such circumstances is to provide a radio reception method and a radio reception apparatus that can effectively mitigate sensitivity suppression due to the influence of adjacent interfering waves without unnecessarily reducing reception sensitivity. There is.

The invention of the wireless reception method according to claim 1 that achieves the above object is to receive a reception signal from an antenna through a filter having a variable pass characteristic.
Based on the received signal input through the filter, the actual received quality of the received signal and the received electric field strength of the radio wave received by the antenna are respectively detected.
The pass characteristic of the filter is controlled based on a comparison between a preset ideal reception quality corresponding to the detected reception electric field strength and the detected actual reception quality.

Furthermore, the invention of the wireless receiver according to claim 2 that achieves the above object is as follows:
An antenna for receiving radio waves in a desired frequency band;
A filter having a variable pass characteristic for passing a received signal from the antenna;
A received electric field strength detecting means for detecting a received electric field strength of a radio wave received by the antenna based on a received signal input through the filter;
Reception quality detection means for detecting the actual reception quality of the received signal based on the received signal input through the filter;
Storage means for storing ideal reception quality with respect to received electric field strength;
Comparison means for comparing the ideal reception quality stored in the storage means corresponding to the reception field strength detected by the reception field strength detection means and the actual reception quality detected by the reception quality detection means;
Control means for controlling the pass characteristic of the filter based on the comparison result by the comparison means;
It is characterized by having.

The invention according to claim 3 is the wireless receiver according to claim 2,
The comparing means compares whether the difference between the ideal reception quality and the actual reception quality is equal to or greater than a first threshold;
The control means controls the pass characteristic of the filter so that the pass band of the received signal is widened when the difference is less than the first threshold value.

The invention according to claim 4 is the radio reception apparatus according to claim 2 or 3,
The comparing means compares whether the difference between the ideal reception quality and the actual reception quality is equal to or greater than a second threshold;
The control means controls the pass characteristic of the filter so that the pass band of the received signal is narrowed when the difference is equal to or greater than the second threshold value.

The invention according to claim 5 is the wireless receiver according to claim 4,
The control means is configured such that the difference is not less than the second threshold value, the received electric field strength detected by the received electric field strength detecting means is less than a third threshold value, and the actual received quality detected by the received quality detecting means is first. When it is less than four thresholds, the pass characteristic of the filter is controlled so that the pass band of the received signal is narrowed.

  According to the present invention, the actual reception field strength and reception quality are detected, and the pass characteristic of the filter is controlled based on a comparison between the ideal reception quality corresponding to the detected reception field strength and the detected actual reception quality. Therefore, it is possible to effectively mitigate sensitivity suppression due to the influence of adjacent interference waves without unnecessarily lowering the reception sensitivity.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a block diagram showing a circuit configuration of a main part of the radio reception apparatus according to the first embodiment of the present invention. This wireless receiving apparatus is exemplified as a mobile phone, and has a control unit 10 that controls the overall operation. The transmission signal is generated by the transmission (Tx) baseband unit 12 based on the reference clock from the TCXO (crystal oscillation circuit with temperature compensation circuit) 11 a of the PLL (phase locked loop) unit 11, and the Tx interstage filter 13. Then, the power is amplified by the power amplifier 14 and then transmitted from the antenna 16 through the Tx filter of the duplexer 15 incorporating the Tx filter and the Rx filter.

  A received signal received by the antenna 16 is amplified by a low noise amplifier (LNA) 17 via an Rx filter of the duplexer 15 and then input to an Rx baseband unit 19 via an Rx interstage filter 18. Processing is performed based on the reference clock from the TCXO 11a of the PLL unit 11.

  Elements constituting the mobile phone other than the wireless unit such as a display unit including an LCD, a battery, and an input unit having operation keys are shown as an application unit 20.

  In the present embodiment, as shown in FIG. 16, when there is a transmission frequency band of another system adjacent to the lower limit frequency of the desired reception band, the influence of adjacent interference waves in the transmission frequency band of the other system. Relieve sensitivity suppression by.

For this reason, in the present embodiment, as shown in FIG. 2, the Rx filter 21 of the duplexer 15 is connected to the filter element 22 between the Rx signal line connected to the antenna (Ant) and the ground. A series circuit of a tunable capacitor 24 composed of a fixed capacitor 23 and a varicap or the like is connected in parallel with the filter element 22, and, for example, the center frequency is substantially constant by a control voltage V _C [V] applied to the tunable capacitor 24. A band-pass filter having a variable pass bandwidth is configured. As for the Tx filter 25, in FIG. 2, a filter element 26 and a fixed capacitor 27 are connected in parallel between the Tx signal line and the ground to form a fixed bandpass filter having a predetermined pass characteristic. Similarly to the filter 21, a tunable capacitor made of a varicap or the like may be connected in series to the fixed capacitor 27, and the pass characteristic of the Tx filter 25 may be controlled according to the control of the pass characteristic of the Rx filter 21. .

  In FIG. 1, the Rx baseband unit 19 includes a C / N detection unit 31 that detects an actual C / N (Carrier to Noise Ratio) indicating reception quality of a received signal, and a received electric field strength. An RSSI detector 32 for detecting the RSSI to be shown is provided, and the actual C / N and RSSI are detected at predetermined timings, respectively. Note that the actual C / N measurement timing by the C / N detection unit 31 is every few seconds, such as when the pilot PN changes, and when the power is turned on.

Further, the control unit 10 applies a control voltage V _C to the comparison unit 34 that performs a comparison operation of required data, and to the tunable capacitor 24 that constitutes the Rx filter 21 of the duplexer 15 based on the calculation result of the comparison unit 34. An Rx filter control unit 35 that controls the pass characteristics of the Rx filter 21 by applying the temperature sensing unit 36 that measures the ambient temperature, and an RSSI-C that indicates an ideal C / N without interference corresponding to RSSI. The memory unit 37 that stores / N data and various threshold values in advance and the buffer unit 38 that temporarily stores necessary data are connected.

Here, the actual C / N and RSSI detected by the C / N detection unit 31 and the RSSI detection unit 32 of the Rx baseband unit 19 respectively change according to the pass characteristics of the Rx filter 21 of the duplexer 15. . Further, the pass characteristic of the Rx filter 21 is narrowed by the control voltage V _C [V], for example, as the control voltage becomes higher, as shown in FIG. The insertion loss also changes so as to increase, and those values also change depending on the temperature T [° C.].

For this reason, as RSSI-C / N data stored in the memory unit 37, the sequential temperatures T ₀ , T ₁ ,..., T _N−1 , T _N (T _N > T ₀ ) [° C.] And sequential control voltages V ₀ , V ₁ ,..., V _N−1 , V _N (V _N > V ₀ ) [V], adjacent to RSSI [dBm], for example, as shown in FIG. The ideal C / N [dB] obtained in each RSSI in a state where no interference wave is received is stored. FIG. 4 shows RSSI-C / N data when T = T ₀ and V _C = V ₀ .

  Next, the operation of the present embodiment will be described with reference to FIGS.

FIG. 5 is a main flowchart showing the overall schematic operation. First, V ₀ [V] is applied as a control voltage V _C to the tunable capacitor 24 constituting the Rx filter 21 of the duplexer 15 from the Rx filter control unit 35 of the control unit 10 by turning on the power of the mobile phone (step S1). Then, the pass characteristic of the Rx filter 21 is set as a normal pass characteristic when no adjacent interference wave is received (step S2).

  Thereafter, the ambient temperature is measured by the temperature sensing unit 36 (step S3), and the optimum characteristic data corresponding to the temperature is obtained from the RSSI-C / N data stored in advance in the memory unit 37 to the current temperature. The RSSI-C / N data that is closest and corresponds to the current control voltage is selected (step S4).

  On the other hand, the C / N detection unit 31 and the RSSI detection unit 32 of the Rx baseband unit 19 detect the actual C / N and RSSI at a predetermined timing, and store the detected values in the buffer unit 38 respectively. 0, recorded as RSSI-0 (step S5).

  Thereafter, using the detected RSSI-0, the corresponding ideal C / N without interference is searched from the RSSI-C / N data selected in Step S4, and the searched ideal C / N is buffered 38. Is stored as C / N-1 (step S6).

  Next, the comparison unit 34 compares and determines whether the difference between the ideal C / N-1 stored in the buffer unit 38 and the detected actual C / N-0 is equal to or greater than a preset threshold value ΔC / N. (Step S7) Based on the comparison determination result, the Rx filter control unit 35 executes the insertion loss improvement control for the Rx filter 21 of the duplexer 15 when it is less than ΔC / N (Step S8), and ΔC / If N or more, C / N improvement control is executed for the Rx filter 21 (step S9). Here, ΔC / N corresponds to the first threshold value and the second threshold value. In the present embodiment, even if there is no interference, the amount of change in C / N that is expected to change depending on the surrounding conditions. And stored in the memory unit 37 in advance.

  The processes in steps S3 to S9 described above are repeated until the power is turned off (step S10), and all the processes are terminated when the power is turned off.

FIG. 6 is a flowchart showing the operation of the insertion loss improvement control in step S8 of FIG. In this insertion loss improvement control, since the difference between the ideal C / N-1 and the detected actual C / N-0 with respect to the detected RSSI is less than ΔC / N, first, the current is applied to the tunable capacitor 24 of the Rx filter 21. It is determined whether or not the applied control voltage V _C is at V ₀ where the insertion loss of the Rx filter 21 is minimized (step S21).

Here, if it is determined that V _C = V ₀ , the control cannot be performed to reduce the insertion loss of the Rx filter 21 to be less than that, so the processing ends and the process returns to the main flow.

On the other hand, if it is determined in step S21 that V _C ≠ V ₀ , the control voltage V _C-1 is changed by one step to the control voltage V _C-1 which is wider than the current control voltage and lower in insertion loss. (Step S22), the process returns to the main flow. Thereby, the input level to the LNA 17 of the adjacent interfering wave can be reduced. Further, the control voltage so varying in steps of one V _C, it is possible to prevent call disconnection due rapid deterioration in C / N.

FIG. 7 is a flowchart showing the operation of the C / N improvement control in step S9 of FIG. In this C / N improvement control, since the difference between the ideal C / N-1 and the detected actual C / N-0 with respect to the detected RSSI is greater than or equal to ΔC / N, first, the tunable capacitor 24 of the Rx filter 21 is applied. It is determined whether or not the currently applied control voltage V _C is at the control voltage V _N that provides the pass characteristics with the largest attenuation amount of the adjacent disturbance wave (step S31).

Here, when it is determined that V _C = V _N , it is impossible to further attenuate the adjacent interfering wave. Therefore, when the process is terminated and the process returns to the main flow, and V _C ≠ V _N is determined. Changes one step to the control voltage V _{C + 1} that has a narrower passband width than the current control voltage and increases the attenuation amount of the adjacent interference wave (step S32), and returns to the main flow.

であらわされる。 Thus, in the present embodiment, the actual C / N detected by the C / N detection unit 31 is used as an index for measuring the level of the adjacent interfering wave. This real C / N is expressed as follows: Pc is the carrier power, Pn is the external noise power, and Pk is the noise power from the adjacent interference wave.

It is expressed.

となって、感度が１０×ｌｏｇＰｋ改善されてＣ／Ｎが増加し、感度抑圧が軽減されることになる。 Here, if the level of the adjacent interference wave decreases and the noise power Pk becomes Pk = 0,

Thus, the sensitivity is improved by 10 × logPk, the C / N is increased, and the sensitivity suppression is reduced.

  For example, if the RSSI-C / N data shown in FIG. 8 is selected as the optimum characteristic data in step S4 of FIG. 5 and the RSSI detected by the RSSI detector 32 is −70 dBm, there is no interference with the RSSI. The ideal C / N at that time is 35 dB. However, if the actual C / N detected by the C / N detection unit 31 is 10 dB, in this case, the noise is increased by 25 dB, that is, the sensitivity is suppressed by 25 dB. The cause of the increase in noise is mainly due to the adjacent interference wave. Here, since the ratio between the interference wave and the noise caused thereby is approximately 1: 1, as described above, the level of the adjacent interference wave can be reduced by increasing the control voltage of the Rx filter 21 and narrowing the pass bandwidth. Can be suppressed by 25 dB. Therefore, if the insertion loss of the Rx filter 21 is ignored, the sensitivity can be improved by 25 dB.

Actually, when the control voltage is increased and the pass band width is narrowed, the insertion loss of the Rx filter 21 also increases. Therefore, the increase in the insertion loss decreases the sensitivity. For example, as shown in FIG. 9, in a normal wide bandwidth pass characteristic where the control voltage V _C is V ₀ , the insertion loss is 0.5 dB, and the attenuation with respect to the interference wave band which is the transmission frequency band of another system is Suppose that it was 1.0 dB. In this state, if an interference wave due to the adjacent frequency is generated and the sensitivity suppression due to the noise becomes 9 dB, the sensitivity is reduced by 9.5 dB together with the insertion loss.

In this case, according to the present embodiment, an appropriate control voltage V _i is applied to the Rx filter 21 to narrow the pass band width, and the pass characteristic is, for example, an insertion loss of 4.0 dB and an attenuation with respect to the interference wave band. The amount is controlled to be 10 dB. Therefore, in this case, the sensitivity suppression due to the interference wave noise of the adjacent frequency is 0 dB, so the overall sensitivity reduction is 4.0 dB together with the insertion loss, compared with the case where the pass characteristic of the Rx filter is not controlled. The sensitivity can be improved by 5.5 dB.

  As described above, in the present embodiment, RSSI is detected, an interference wave is detected based on a comparison between an ideal C / N and an actual C / N in the detected RSSI, and the level of the interference wave is determined. Since the pass characteristic of the Rx filter 21 of the duplexer 15 is controlled, even when the RSSI is high, the adjacent interference wave can be reliably detected and the interference wave noise can be suppressed. When the difference between the ideal C / N and the actual C / N is less than the threshold value ΔC / N, that is, when the sensitivity suppression of the adjacent interfering wave is smaller than the insertion loss of the Rx filter 21, the pass bandwidth is Since the pass characteristic is controlled so that the insertion loss becomes wider and the insertion loss becomes smaller, the reception sensitivity can be further improved. Therefore, it is possible to effectively mitigate sensitivity suppression due to the influence of adjacent interference waves without unnecessarily lowering the reception sensitivity.

  In addition, since the Rx filter originally provided in the duplexer 15 is configured so that the pass characteristic is variable and the pass characteristic is controlled, the circuit configuration can be simplified.

(Second Embodiment)
FIG. 10 is a block diagram showing a circuit configuration of a main part of the radio reception apparatus according to the second embodiment of the present invention. In the present embodiment, Rx filter temperature characteristic data is also stored in the memory unit 37 in advance in the configuration shown in FIG. 1, and the other configurations are the same as those in FIG.

Here, as shown in FIG. 11, the Rx filter temperature characteristic data includes Rx filter 21 at each control voltage for each temperature T = T ₀ , T ₁ ,..., T _N−1 , T _N [° C.]. The insertion loss due to and the attenuation amount of the adjacent interference wave are stored. Note that the Rx filter pass characteristic data for each temperature can be obtained, for example, without storing attenuation amounts and insertion losses in all control voltages V ₀ , V ₁ ,..., V _N−1 , V _N [V]. Only ₀ , V ₂ ,..., V _N and every other data or every several data may be stored, and other control voltage data may be obtained by interpolation.

  Next, the operation of the present embodiment will be described. This embodiment is different from the flowchart shown in FIG. 5 in the characteristic data selection process in step S4 and the C / N improvement control in step S9.

  That is, in step S4, as the optimum characteristic data corresponding to the ambient temperature measured by the temperature sensing unit 36 in step S3, as in the first embodiment, the RSSI-C / The RSSI-C / N data closest to the current temperature and corresponding to the current control voltage is selected from the N data, and the current temperature is determined from the Rx filter temperature characteristic data stored in the memory unit 37 in advance. Select the nearest Rx filter pass characteristic data

In step S9, C / N improvement control is executed according to the flowchart shown in FIG. That is, in the state in which the C / N improvement control is performed, the difference between the ideal C / N-1 and the detected actual C / N-0 is greater than or equal to ΔC / N. It is determined whether or not the control voltage V _C is at the control voltage V _N having the largest attenuation (step S41). If it is determined that V _C = V _N , the adjacent interference wave is further attenuated. Since control is not possible, the process ends and returns to the main flow.

On the other hand, if it is determined that V _C ≠ V _N , the difference C / N _d between the ideal C / N-1 and the actual C / N-0 with respect to the current RSSI is acquired (step S42), and step S42 is performed. from Rx filter pass characteristic data is selected in step S4 to obtain the attenuation Att _C of adjacent interfering wave band by the current control voltage _{V C} (step S43).

Thereafter, it is determined whether or not the selected Rx filter pass characteristic data includes a control voltage corresponding to the minimum Att among the attenuation (Att) controls exceeding (Att _C + C / N _d ) (step) S44), in some cases, stored in the buffer unit 38 and the control voltage Vm as Vcb (step S45), if not, stores the _{V N} is the maximum value of the control voltage to the buffer unit 38 as Vcb ( Step S46).

Next, as a comparison voltage of each control voltage from the current control voltage V _C to the control voltage Vcb stored in the buffer unit 38, it performs the following calculation (step S47).

First, a reduction prediction of sensitivity suppression at the comparison voltage V is performed. Therefore, the difference between the attenuation amount (Att (V) −Att _C ) when the current control voltage V _C of the Rx filter 21 is changed to the comparison voltage V and the C / N _d calculated in step S42 is It is determined whether it is 0 or less (step S48). As a result, when it is 0 or less, the predicted sensitivity suppression SD-F when the control voltage is V is set to 0 (step S49), and when it exceeds 0, the predicted sensitivity suppression SD-F is set to C / N _d. − (Att (V) −Att _C ) (Step S50).

  The same processing is executed for the next comparison voltage V + 1, and the expected sensitivity suppression at that time is SD-S (steps S51 to S53).

  Thereafter, the total loss-F of the insertion loss Loss (V) of the Rx filter 21 at the comparison voltage V and the expected sensitivity suppression SD-F is calculated (step S54), and the insertion loss Loss (V + 1) at the comparison voltage V + 1 is predicted. The total loss-S with the sensitivity suppression SD-S is calculated (step S55), and the magnitude relationship between the two is compared (step S56).

As a result, when Loss-F is equal to or lower than Loss-S, control with Loss-F is predicted to be optimal control, so the control voltage V _{C is set} to V (step S57), and the process returns to the main loop. On the other hand, when Loss-F exceeds Loss-S, the comparison voltage V is set to V + 1 (step S58), and the above determination flow from step S47 is repeated.

  Even if the comparison voltage V becomes Vcb, if Loss-F exceeds Loss-S in step S56, Vcb is predicted to be the optimum control voltage, so the control voltage Vc is set to Vcb (step S59). Return to flow.

  According to the present embodiment, in the C / N improvement control, the control voltage Vc of the Rx filter 21 uses the Rx filter pass characteristic data, and the attenuation amount and insertion loss of the adjacent jamming band are minimized. Since it is controlled to an optimum value, sensitivity suppression due to the influence of adjacent interfering waves can be more effectively mitigated without unnecessarily lowering the reception sensitivity than in the first embodiment.

(Third embodiment)
FIG. 13 is a flowchart showing the main operation of the radio receiving apparatus according to the third embodiment of the present invention. In this embodiment, in the C / N improvement control in the second embodiment shown in FIG. 12, when it is determined in step S41 that V _C ≠ V _N , the ideal C / N for the current RSSI in step S42. -1 and prior to obtaining the difference C / _{N d} of the actual C / N-0, it executes the determination processing of the RSSI at step S61.

  In the RSSI determination processing in step S61, as shown in FIG. 14, first, it is determined whether RSSI-0 measured in step S5 of FIG. 5 is equal to or greater than a preset third threshold RSSI-th ( Step S62). Here, the RSSI-th is stored in the memory unit 37 in advance as a value that can obtain a sufficient C / N in a non-interfering state, for example.

  As a result, when RSSI-0 is less than RSSI-th, it is determined that it is necessary to suppress the interference wave even with a small amount of interference wave, and the process proceeds to step S42 of the C / N improvement flow. On the other hand, when RSSI-0 is equal to or greater than RSSI-th, it is determined whether or not the actual C / N-0 measured in step S5 in FIG. 5 is equal to or greater than a preset fourth threshold C / N-th. (Step S63). Here, C / N-th is stored in the memory unit 37 in advance as a value that can secure a sufficient C / N even when the interference wave level fluctuates when the measured value of RSSI is RSSI-th.

  As a result, when the actual C / N-0 is less than C / N-th, it is determined that it is necessary to suppress the interference wave even with a small amount of interference wave, and the process proceeds to step S42 of the C / N improvement flow. . On the other hand, when the actual C / N-0 is equal to or greater than C / N-th, there is no need to improve C / N immediately. Therefore, the process returns to the main flow shown in FIG. The process proceeds to S10. FIG. 15 shows the relationship between the selected RSSI-C / N data and the first and second thresholds ΔC / N, the third threshold RSSI-th, and the fourth threshold C / N-th. .

  According to the present embodiment, even if the RSSI is RSSI-th or more and the measured actual C / N-0 is C / N-th or more, that is, even if the sensitivity is somewhat suppressed by the interference wave, Rx In the state where it is not necessary to control the filter 21 to further suppress the interference wave, the C / N improvement control is not performed. Therefore, the sensitivity suppression due to the influence of the adjacent interference wave can be suppressed without unnecessarily reducing the reception sensitivity. It can be relaxed more efficiently.

  In addition, this invention is not limited only to the said embodiment, Many deformation | transformation or a change is possible. For example, in the first embodiment, the RSSI determination process shown in the third embodiment may be executed between step S31 and step S32 of the C / N improvement control shown in FIG. . In the above embodiment, both the first threshold value and the second threshold value are equal to ΔC / N. However, for example, (first threshold value <second threshold value), and both are made different to detect the detected RSSI. When the difference between the ideal C / N-1 and the detected actual C / N-0 is less than the first threshold value, the insertion loss improvement control is executed, and when the difference is equal to or greater than the second threshold value, the C / N improvement control is executed. It can also be executed.

  Furthermore, the pass characteristics of the Rx filter are not limited to the case where the center bandwidth is fixed and the pass bandwidth is controlled, but the cutoff frequency on the side where the adjacent adjacent interference wave exists is controlled, or the pass bandwidth is substantially constant. As a whole, shift control of the whole (center frequency) can be performed. The Rx filter having a variable pass characteristic can be provided separately from the duplexer. Furthermore, the reception quality is not limited to C / N, and other evaluation values such as S / N can be used. Further, the present invention can be effectively applied not only to a mobile phone but also to a wireless reception device used for other wireless terminal devices such as a PDA and a card terminal.

It is a block diagram which shows the circuit structure of the principal part of the radio | wireless receiver which concerns on 1st Embodiment of this invention. It is a circuit diagram which shows the structure of the duplexer shown in FIG. It is a figure which shows the passage characteristic of a Rx filter. It is a figure which shows an example of RSSI-C / N data stored in the memory part of FIG. It is a main flowchart which shows schematic operation | movement of 1st Embodiment. It is a flowchart which shows the operation | movement of the insertion loss improvement control in step S8 of FIG. It is a flowchart which shows the operation | movement of C / N improvement control in FIG.5 S9. It is a figure which shows RSSI-C / N data for demonstrating the operation | movement of 1st Embodiment. It is a figure which shows the passage characteristic of a Rx filter. It is a block diagram which shows the circuit structure of the principal part of the radio | wireless receiver which concerns on 2nd Embodiment of this invention. It is a figure which shows the Rx filter temperature characteristic data stored in the memory part of FIG. It is a flowchart which shows the operation | movement of the improvement control of C / N by 2nd Embodiment. It is a flowchart which shows the principal part operation | movement of the radio | wireless receiver which concerns on 3rd Embodiment of this invention. It is a flowchart which shows the operation | movement of the RSSI determination process in step S61 of FIG. It is a figure which shows the relationship between RSSI-C / N data and threshold value RSSI-th, threshold value C / N-th, and (DELTA) C / N. It is a figure which shows the pass characteristic of the conventional Rx filter. It is a figure which shows the relationship between the interference wave level and reception sensitivity in a mobile telephone.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Control part 11 PLL part 12 Tx baseband part 13 Tx interstage filter 14 Power amplifier 15 Duplexer 16 Antenna 17 Low noise amplifier (LNA)
18 Rx Interstage Filter 19 Rx Baseband Unit 20 Application Unit 21 Rx Filter 22, 26 Filter Element 23, 27 Fixed Capacitor 24 Tunable Capacitor 25 Tx Filter 31 C / N Detection Unit 32 RSSI Detection Unit 34 Comparison Unit 35 Rx Filter Control Section 36 Temperature sensing section 37 Memory section 38 Buffer section

Claims (3)

When receiving the received signal from the antenna through a filter with variable pass characteristics,
Based on the received signal input through the filter, the actual received quality of the received signal and the received electric field strength of the radio wave received by the antenna are respectively detected.
A wireless reception method, wherein a pass characteristic of the filter is controlled based on a comparison between a preset ideal reception quality corresponding to the detected received electric field strength and the detected actual reception quality. An antenna for receiving radio waves in a desired frequency band;
A filter having a variable pass characteristic for passing a received signal from the antenna;
A received electric field strength detecting means for detecting a received electric field strength of a radio wave received by the antenna based on a received signal input through the filter;
Reception quality detection means for detecting the actual reception quality of the received signal based on the received signal input through the filter;
Storage means for storing ideal reception quality with respect to received electric field strength;
Comparison means for comparing the ideal reception quality stored in the storage means corresponding to the reception field strength detected by the reception field strength detection means and the actual reception quality detected by the reception quality detection means;
Control means for controlling the pass characteristic of the filter based on the comparison result by the comparison means;
A wireless receiver characterized by comprising: The comparing means compares whether the difference between the ideal reception quality and the actual reception quality is a first threshold value or more;
3. The radio reception according to claim 2, wherein when the difference is less than the first threshold, the control unit controls the pass characteristic of the filter so that a pass band of the reception signal is widened. apparatus.

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