JP4355466B2 - Mobile communication terminal apparatus, reception sensitivity deterioration preventing method used therefor, and program thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mobile communication terminal which improves the desired wave to disturbing wave ratio after despreading by reducing the high power of disturbing waves mixed in a band of desired waves, thereby reducing the suppression of the receiving sensitivity. <P>SOLUTION: An antenna 11 receives incoming waves and a radio unit 12 amplifies the waves received by the antenna 11. An A/D converter 13 A/D- converts the received waves amplified by the radio unit 12. A memory 14 stores values after A/D conversion by the A/D converter 13 synchronously with a frame synchronizing signal from a CDMA demodulator 16. An arithmetic unit 15 monitors values after A/D conversion from the memory 14 every frame, and reduces the value after A/D conversion to a predetermined value for the portion having periodicity at a level higher than the predetermined value. The CDMA demodulator 16 performs demodulation on the despread received wave based on the values received from the arithmetic unit 15. <P>COPYRIGHT: (C)2003,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a mobile communication terminal apparatus, a reception sensitivity deterioration preventing method used therefor, and a program thereof, and more particularly, to a system that reduces reception sensitivity suppression in a CDMA (Code Division Multiple Access) receiver.
[0002]
[Prior art]
Conventionally, in a CDMA receiver, as shown in FIG. 7, after a received wave received by a radio unit 32 via an antenna 31 and spread spectrum is converted by an A / D (analog / digital) conversion unit 33, The spectrum demodulation unit 34 performs despreading.
[0003]
That is, in the conventional CDMA receiver, the spectrum-spread received wave passes from the antenna 31 through the radio unit 32 and is input to the A / D conversion unit 33, and the value after this A / D conversion is directly used by the spectrum demodulation unit 34. Demodulated and data are extracted.
[0004]
[Problems to be solved by the invention]
However, in the above-described conventional CDMA receiver, as shown in FIG. 8, if a periodic noise such as a harmonic of a clock is mixed in the received wave band at a high level, the noise level is not limited even if despreading is performed. Remains at a high level to some extent, and the signal-to-noise ratio deteriorates, resulting in a deterioration in reception sensitivity.
[0005]
That is, the conventional CDMA receiver has a problem that reception sensitivity deteriorates when a high-power interference wave (periodic noise) is mixed in the band of the desired wave. For example, periodic noise includes “clock harmonics”, “transmitted waves + clock harmonics” generated from a circuit in a CDMA receiver (for example, a switching circuit or a clock circuit that performs periodic operations), and the like. There are often.
[0006]
As a method of suppressing this periodic noise generation, measures are taken to suppress the generation of the noise at the time of circuit design, but this countermeasure prevents the deterioration of reception sensitivity due to unexpected noise generation. I can't. Incidentally, noise other than periodic noise does not affect the subsequent processing by the despreading processing in the CDMA receiver.
[0007]
Further, the conventional CDMA receiver has a problem that the interference wave cannot be reduced or eliminated because the A / D converted value is simply supplied to the spectrum demodulator.
[0008]
Accordingly, an object of the present invention is to solve the above-mentioned problems and to reduce the power of the high power jamming wave mixed in the band of the desired wave to improve the ratio of the desired wave / jamming wave after despreading. Another object of the present invention is to provide a mobile communication terminal apparatus capable of reducing suppression of reception sensitivity, a reception sensitivity deterioration prevention method used therefor, and a program thereof.
[0009]
[Means for Solving the Problems]
A mobile communication terminal apparatus according to the present invention is a mobile communication terminal apparatus that demodulates by performing despreading after analog / digital conversion of a spectrum-spread received wave, and stores the analog / digital conversion value before despreading in a database And the location of periodic noise in the database converted analog / digital conversion value is specified by the number of data from the beginning of the frame, and the setting is preset for the periodic noise at the specified location. Correction processing means for performing correction processing by value.
[0010]
The reception sensitivity deterioration prevention method according to the present invention is a method for reducing reception sensitivity suppression of a mobile communication terminal apparatus that demodulates by performing despreading after analog / digital conversion of a spectrum-spread received wave. A step of creating a database of analog / digital conversion values, and a location of periodic noise in the database of the analog / digital conversion values specified by the number of data from the beginning of the frame, and periodic noise at the specified location And a step of performing a correction process using preset setting values.
[0011]
The program of the reception sensitivity deterioration prevention method according to the present invention is a program of a reception sensitivity deterioration prevention method of a mobile communication terminal apparatus that demodulates by performing despreading after analog-to-digital conversion of a spread spectrum received wave. The computer of the communication terminal device stores the analog / digital conversion value before despreading in a database, and the location of periodic noise in the analog / digital conversion value in the database is the number of data from the beginning of the frame. And performing a correction process using a preset value for the periodic noise at the specified location .
[0012]
That is, the mobile communication terminal apparatus according to the present invention uses a CDMA (Code Division Multiple Access) receiver to suppress reception sensitivity due to periodic noise such as clock harmonics in analog / digital (A / D). It is characterized in that the values after conversion are made into a database and reduced by intentionally deleting or offsetting the data of the noise part.
[0013]
More specifically, the mobile communication terminal device of the present invention includes an antenna that receives a received wave, a radio unit that amplifies the received wave, an A / D converter that A / D converts the received wave, A memory for storing the value after A / D conversion, and the value after A / D conversion are monitored for each frame in synchronization with the frame synchronization signal from the CDMA demodulator, and the cycle is set at a level higher than a preset set value. An arithmetic processing unit that reduces the value after A / D conversion to a set value for a characteristic part, and a CDMA demodulating unit that demodulates the received wave by despreading based on the value received from the arithmetic processing unit Has been.
[0014]
The mobile communication terminal apparatus of the present invention adopts the configuration as described above, creates a database of values after A / D conversion, adds offset processing to the noise part, reduces the noise level, and reduces sensitivity suppression. Has the effect of
[0015]
In this way, the values after A / D conversion are made into a database, and the periodic noise part is offset, so a high-power interference wave (periodic noise) mixed in the desired wave band. Therefore, it is possible to improve the ratio of the desired wave / interfering wave after despreading, so that it is possible to reduce the suppression of reception sensitivity.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a mobile communication terminal apparatus according to an embodiment of the present invention. FIG. 1 shows a CDMA (Code Division Multiple Access) receiver as the mobile communication terminal device 1 according to an embodiment of the present invention.
[0017]
The mobile communication terminal device 1 includes an antenna 11, a radio unit 12, an A / D conversion unit 13, a memory 14, an arithmetic processing unit 15, a CDMA demodulation unit 16, and a recording medium 17. The recording medium 17 stores a program to be executed by a computer (not shown) of the mobile communication terminal device 1, and writing control to the memory 14 and processing of the arithmetic processing unit 15 are realized by execution of the program by the computer. Is done.
[0018]
The antenna 11 receives the received wave, and the radio unit 12 amplifies the received wave received by the antenna 11. The A / D converter 13 performs A / D conversion on the received wave amplified by the wireless unit 12. The memory 14 accumulates the values after A / D conversion in the A / D converter 13 in synchronization with the frame synchronization signal from the CDMA demodulator 16 and creates a database.
[0019]
The arithmetic processing unit 15 monitors the value after A / D conversion from the memory 14 for each frame, and sets the value after A / D conversion for a portion having a periodicity at a level higher than a preset setting value. To decrease. The CDMA demodulator 16 demodulates the received wave by performing a despreading process based on the value received from the arithmetic processor 15. If the arithmetic processing unit 15 does not detect periodic noise, the CDMA demodulation unit 16 receives the A / D converted value stored in the memory 14 and passed through the arithmetic processing unit 15 as it is.
[0020]
FIG. 2 is a diagram showing a data storage method in the memory 4 of FIG. In FIG. 2, the memory 14 stores data in units of one frame in synchronization with the frame synchronization signal from the CDMA demodulator 16.
[0021]
In this embodiment, it is assumed that the A / D conversion value of the desired wave is “0x07” and the A / D conversion value of the interference wave (noise) is “0xCC”. If the arithmetic processing unit 5 takes the average of the A / D conversion values for each frame, it can be seen that the level of the desired wave is about “0x07”. This is performed for an arbitrary number of frames, and a threshold value is determined from the average value. In this embodiment, it is assumed that a margin is added to the average value of “0x07” and the threshold value is set to “0x20”.
[0022]
In this embodiment, the synchronization is performed in the frame, and the interference wave is also a periodic noise. Therefore, the location of the interference wave existing in one frame is always almost constant. Therefore, the arithmetic processing unit 15 determines a threshold value for detecting periodic noise, and compares the threshold value for the portion where the interference wave specified from the next frame specifying the location of the interference wave exists. Then, a process (rounding process) for converting the original A / D conversion value into a preset setting value is performed. This processed value is transmitted to the CDMA demodulator 16 where despreading processing is performed. The set value is a fixed value set in advance so that the reception sensitivity does not deteriorate.
[0023]
Note that the configuration and operation of the antenna 11, the radio unit 12, and the CDMA demodulation unit 16 shown in FIG. 1 are well known to those skilled in the art and are not directly related to the present invention. Description of is omitted.
[0024]
FIGS. 3 and 4 are diagrams illustrating a reception sensitivity suppression reduction operation of the mobile communication terminal device according to the embodiment of the present invention. FIG. 5 is a flowchart illustrating an operation of the mobile communication terminal device according to the embodiment of the present invention. . With reference to FIGS. 1 to 5, the reception sensitivity suppression mitigation operation of the mobile communication terminal apparatus according to one embodiment of the present invention will be described. Note that the processing shown in FIG. 5 is realized by the computer of the mobile communication terminal device 1 executing the program of the recording medium 17.
[0025]
The received wave that is received by the antenna 11 and spectrum-spread is amplified by the radio unit 12 (step S1 in FIG. 5) and supplied to the A / D conversion unit 13. The A / D converter 13 A / D converts the received wave (step S2 in FIG. 5), and supplies it to the memory 14. The memory 14 stores data in units of one frame in synchronization with the frame synchronization signal from the CDMA demodulator 6 and creates a database (step S3 in FIG. 5).
[0026]
The arithmetic processing unit 15 calculates the average value of each A / D-converted frame from the frame unit data stored in the memory 14 (step S4 in FIG. 5), and adds a preset margin to the average value. Then, a threshold value for detecting the interference wave (noise) is determined (step S5 in FIG. 5).
[0027]
The arithmetic processing unit 15 compares the determined threshold value with the A / D conversion value for each frame (step S6 in FIG. 5), and profiles a place where the value is larger than the threshold value (time from the beginning of the frame) ( FIG. 5 step S7).
[0028]
When the value of the same place exceeds the threshold value in any number of frames (step S8 in FIG. 5), the arithmetic processing unit 15 determines that an interference wave (noise) exists at that place (step S9 in FIG. 5), and starts from the next frame. The value of the place is replaced with a preset setting value (step S10 in FIG. 5) and supplied to the CDMA demodulator 16. The CDMA demodulation unit 16 performs a despreading process based on the supplied value (step S11 in FIG. 5).
[0029]
In this embodiment, as shown in FIG. 3, the values after A / D conversion are made into a database, and by adding offset processing to the noise part, as shown in FIG. 4, the noise level is reduced and sensitivity suppression is performed. It has the effect that it can be reduced.
[0030]
As described above, in this embodiment, the A / D converted values are stored in the memory 14 in units of frames and stored in a database, so that the periodic noise location can be represented by the number of data (time) from the beginning of the frame. Can be identified.
[0031]
In this embodiment, a threshold value is set, and those that periodically exceed the threshold value are determined as noise, and the value is reduced to the set value, so that the noise level before despreading can be reduced.
[0032]
Therefore, in this embodiment, it is possible to reduce the power of the high power jamming wave (periodic noise) mixed in the desired wave band and improve the ratio of the desired wave / jamming wave after despreading. The suppression of reception sensitivity can be reduced. This effect is effective both when the mobile communication terminal device 1 is shipped and after it is shipped.
[0033]
FIG. 6 is a block diagram showing a configuration of a mobile communication terminal apparatus according to another embodiment of the present invention. In FIG. 6, a mobile communication terminal device 2 according to another embodiment of the present invention has an arithmetic processing unit 15 having a communication function with a terminal CPU (central processing unit) 21 of the receiver body, and the terminal CPU 21 is connected to an external interface 22. 1 is the same as that of the mobile communication terminal apparatus according to the embodiment of the present invention shown in FIG. 1, and the same components are denoted by the same reference numerals. The operation of the same component is the same as that of the embodiment of the present invention. The write control for the memory 14, the processing of the arithmetic processing unit 15, and the data transfer between the arithmetic processing unit 15 and the terminal CPU 21 are stored in the recording medium 17 by the computer (not shown) of the mobile communication terminal device 2. Realized by executing the program.
[0034]
The arithmetic processing unit 15 has an A / D conversion value stored in the memory 14 having at least one of a place designated by the terminal CPU 21 (where noise occurs with periodicity), a designated setting value, and a threshold margin. And the sensitivity suppression mitigation process can be controlled by communication from the terminal CPU 21.
[0035]
Thereby, in this embodiment, the sensitivity suppression reduction process can be stopped, and the effect of sensitivity suppression reduction can be verified. Note that the designated location, designated setting value, threshold margin, and the like for the terminal CPU 21 are set from an external information processing apparatus (such as a personal computer) via the external interface 22.
[0036]
Thus, in the present embodiment, since the arithmetic processing unit 15 has a communication function with the terminal CPU 21 of the receiver, in addition to the automatic processing for reducing sensitivity suppression, the frequency of noise that causes sensitivity suppression, the approximate level If you know, you can specify it and execute the process. Further, the set value used in the arithmetic processing unit 15 can also be changed via the terminal CPU 21.
[0037]
In this embodiment, the arithmetic processing unit 15 has a communication function with the terminal CPU 21, but instead of the communication function with the terminal CPU 21, communication with the outside such as RS-232C, USB (Universal Serial Bus). It can also be configured to have a function. In this case, it is also possible to directly set the frequency, approximate level, set value, etc. of noise causing sensitivity suppression from the outside in the arithmetic processing unit 15.
[0038]
【The invention's effect】
As described above, the present invention provides a database of analog / digital conversion values before despreading in a mobile communication terminal apparatus that demodulates by performing despreading after analog / digital conversion of the spread spectrum received wave. By correcting the periodic noise in the converted analog / digital conversion value with a preset setting value, the power of the high interference wave mixed in the band of the desired wave is lowered and the signal after despreading is reduced It is possible to improve the ratio of the desired wave / interfering wave, and to reduce the reception sensitivity.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a mobile communication terminal apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a data storage method in the memory of FIG. 1;
FIG. 3 is a diagram illustrating a reception sensitivity suppression mitigation operation of a mobile communication terminal device according to an embodiment of the present invention.
FIG. 4 is a diagram illustrating a reception sensitivity suppression reduction operation of the mobile communication terminal according to an embodiment of the present invention.
FIG. 5 is a flowchart showing an operation of the mobile communication terminal according to an embodiment of the present invention.
FIG. 6 is a block diagram showing a configuration of a mobile communication terminal apparatus according to an embodiment of the present invention.
FIG. 7 is a block diagram showing a configuration of a mobile communication terminal apparatus according to a conventional example.
FIG. 8 is a diagram illustrating an operation of a mobile communication terminal device according to a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1, 2 Mobile communication terminal device 11 Antenna 12 Radio | wireless part 13 A / D conversion part 14 Memory 15 Operation processing part 16 CDMA demodulation part 17, 23 Recording medium 21 Terminal CPU
22 External interface

Claims (7)

A mobile communication terminal apparatus for demodulating by performing despreading after analog-to-digital conversion of a spread spectrum received wave, means for creating a database of the analog / digital conversion values before despreading, Further, the correction processing means for specifying the location of the periodic noise in the analog / digital conversion value by the number of data from the head of the frame and performing the correction processing by the preset value for the periodic noise at the specified location. And a mobile communication terminal device. The mobile communication terminal apparatus according to claim 1, wherein the correction processing means reduces the value after the analog / digital conversion to the set value for the specific portion having a periodicity at a level higher than the setting. . Wherein the correction processing means includes a function of communicating with the outside, claims and performing at least one of the correction processing of the said set value and said margin and said periodic noise place from the outside The mobile communication terminal device according to claim 1 . A method of preventing reception sensitivity deterioration of a mobile communication terminal apparatus for demodulating by performing despreading after analog-to-digital conversion of a spectrum-spread received wave, wherein the analog / digital conversion value before despreading is made into a database And the location of the periodic noise in the analog / digital conversion value stored in the database is specified by the number of data from the beginning of the frame, and the periodic noise at the specified location is corrected by a preset setting value. A method for preventing reception sensitivity deterioration. 5. The reception sensitivity according to claim 4 , wherein the step of performing the correction processing reduces the value after the analog / digital conversion to the set value for the specific portion having a periodicity at a level higher than the setting. Deterioration prevention method. 6. The correction process according to claim 4 , wherein the correction process includes performing a correction process using at least one of the set value from the outside, the margin, and the location of the periodic noise. Or a method for preventing reception sensitivity deterioration. A program of a reception sensitivity deterioration prevention method for a mobile communication terminal device that demodulates by performing despreading after analog / digital conversion of a spread spectrum received wave, the computer of the mobile communication terminal device before the despreading A process of creating a database of the analog / digital conversion values, and a location of periodic noise in the database of the analog / digital conversion values specified by the number of data from the beginning of the frame, and periodicity at the specified location The program for performing the process which performs the correction process by the preset setting value with respect to noise.

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