JP2008160731A - Radio communication unit and control method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain solution of the problem that if deviation of a transmitter is deviated from a specified value, reception sensitivity is extremely reduced and reception may be disabled occasionally but conventionally, means for correcting the deviation during operation of a radio communication unit is not known. <P>SOLUTION: In the case where communication quality of an incoming call signal becomes worse than a fixed value, a deviation correction signal is transmitted to call or control deviation correction of an opposite-side transmitter. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wireless communication device and a control method thereof, and more particularly, to a means for improving reception sensitivity by correcting a deviation of a transmission unit.

In recent years, land mobile radio (LMR) for commercial use has been reduced in frequency band per channel and digitized from the viewpoint of frequency utilization efficiency. When digitizing, frequency division multiplexing using frequency modulation keying (FSK) of FM modulation because of coexistence with existing analog wireless communication devices, diversion of existing equipment, ease of control, etc. (Frequency Division Multiple Access (FDMA)) or phase shift keying (PSK) that changes the phase is often employed.
Further, as frequency modulation means and phase modulation means, for example, frequency control of a voltage controlled oscillator (VCO) or a temperature compensated crystal oscillator (TCXO) using a crystal resonator as a frequency oscillation source. A frequency shift and a phase shift are given by superimposing data and audio signals to be transmitted on the signal.

On the other hand, in a communication system that transmits information by using a phase shift amount or a frequency shift amount of a carrier wave such as PSK or FSK, a frequency shift value or a phase shift value (hereinafter collectively referred to as a deviation). Since the frequency bandwidth of the carrier wave to be transmitted fluctuates, the maximum value of the deviation is limited so as not to exceed the specified value.
In recent years, transmission / reception in a wireless communication apparatus often transmits various data as well as audio signals. In digital communication, audio signals are also digitally encoded and transmitted. As a method for adjusting the deviation between the audio signal and the data when transmitting the audio signal and the data, for example, the method proposed in Patent Document 1 exists. This eliminates problems in FM modulation and PM modulation by adding a selective call signal or the like to the signal from the microphone and supplying it as the VCO control signal of the PLL circuit, as will be described later. Means available in the practice of the present invention.
JP-A-11-68719

By the way, the deviation of the transmission signal of the radio communication device is generally adjusted semi-fixed by a resistor, a preset switch, etc. so that the maximum value becomes a certain value or less by the modulation circuit of the transmitter. Depending on the situation, it is carried out in a maintenance factory where various measuring instruments are prepared.
However, the set deviation may fluctuate due to various causes. In general, if the maximum deviation value set in the modulation circuit increases, the frequency bandwidth of the transmission signal widens and interferes with adjacent channels and other communication systems, so an excessive signal is input to the modulation circuit. Is configured so that the deviation does not exceed a certain value. Also, in multi-level modulation such as digital modulation, modulation is performed so that multi-level deviation values (frequency shift amount and phase shift amount) correspond to several levels of signal level, so each stage of deviations. The value varies in proportion to the set maximum deviation value.
In such a usage situation, if the maximum deviation set value fluctuates due to various causes, the detection level at the time of reception detection fluctuates, and the practical reception sensitivity decreases.

FIG. 8 is a graph showing an example in which the relationship between the deviation error (horizontal axis) and the bit error rate (vertical axis) of the transmitter is measured, where 0 at the center of the horizontal axis is 1050 (Hz) taking quaternary FSK as an example. And the bit error rate (%) when each is changed in the range of ± 500 (Hz) in increments of 100 (Hz) to the left and right. As is apparent from this figure, if an error of about ± 250 Hz or more occurs on both the plus side and the minus side, the bit error rate rapidly deteriorates and data restoration becomes impossible.
However, conventionally, when an error occurs in a deviation, there is no means for correcting this, and the adjustment is carried out by bringing it to a maintenance service station of a wireless communication device having various measuring devices. Therefore, even if the deviation decreases due to some cause and an error occurs, the error reaches a large error of about ± 250 Hz as shown in FIG. 8 and is not noticed until reception becomes impossible. The current situation was operating radio communications equipment.
The present invention has been made in view of the problems associated with the occurrence of deviation errors in such conventional wireless communication devices, and correction of deviation errors is performed automatically or manually while operating the wireless communication device. It is an object of the present invention to provide a radio communication apparatus and a control method thereof capable of always maintaining the best reception sensitivity.

In order to solve the above problems, the present invention provides a wireless communication device according to claim 1, which is a wireless communication device including a frequency / phase modulation transmission unit and a reception unit. A means for detecting the field strength level or reception quality, a means for comparing the result with a preset threshold value, and a comparison correction signal when the field strength level or reception quality of the received signal falls below the threshold value as a result of the comparison. And means for transmitting.
The wireless communication device according to claim 2 is a wireless communication device including a frequency / phase modulation transmission unit and a reception unit, and when the deviation correction signal is received from the counterpart wireless communication device, means for notifying that fact or automatic And a means for correcting the deviation of the transmission unit.
According to a third aspect of the present invention, in the wireless communication device according to the first aspect, a means for detecting a frame synchronization word transmitted from the counterpart wireless communication device, a received frame detection word, and an ideal frame synchronization word And a means for comparing the detected error with a preset threshold value, and a means for transmitting a deviation correction signal to the counterpart wireless communication device when the error is larger than the threshold value. And

According to a fourth aspect of the present invention, in the wireless communication device according to the second aspect, when the deviation of the transmission unit is corrected in response to the deviation correction signal received from the counterpart wireless communication device, the passage of a preset time is measured. A timer means and means for resetting a corrected deviation when a set time has elapsed are provided.
The invention according to claim 5 relates to a control method of a radio communication device, and in a communication method when a radio communication device having a frequency / phase modulation transmission unit and a reception unit communicate with each other, an incoming call is received from a partner radio communication device. A process for detecting a field strength level or reception quality of a received signal, a process for comparing the result with a preset threshold value, and a comparison result when the field strength level or reception quality of the received signal falls below the threshold value And a process of transmitting a deviation correction signal, a process of notifying that when a deviation correction signal is received from the counterpart wireless communication device, or a process of automatically correcting a deviation of the transmission unit.

According to a sixth aspect of the present invention, in the method for controlling a wireless communication device according to the fifth aspect, the wireless communication device further detects a frame synchronization word transmitted from the counterpart wireless communication device, and the received and detected frame. Processing to detect the error between the synchronization word and the ideal frame synchronization word, processing to compare the detected error with a preset threshold value, and send a deviation correction signal to the partner wireless communication device when the error is larger than the threshold value Including a process to perform.
The invention according to claim 7 is the method for controlling a wireless communication device according to claim 5 or 6, wherein when the deviation of the transmission unit is corrected in response to the deviation correction signal received from the counterpart wireless communication device, a preset time And a timer process for measuring the elapsed time and a process for resetting the corrected deviation when the set time has elapsed.

  Since the present invention is configured as described above, the following effects can be obtained. That is, in the first and second aspects of the invention, in a wireless communication device having a frequency / phase modulation scheme transmission unit and reception unit, the field strength level or reception quality of the received signal received from the counterpart wireless communication device. Since it is configured to send a deviation correction signal to the counterpart wireless communication device when the value is below the threshold, the possibility that the deviation of the own station has decreased on the side receiving this correction signal is detected. It is possible to manually urge the operator to correct the deviation or automatically correct the deviation by determining that there is an error and notifying the fact. Further, even when the deviation set value is normal, by increasing the deviation within an allowable range, an effect of improving the reception sensitivity at the communication partner can be obtained.

According to a third aspect of the present invention, the wireless communication device according to the first aspect further comprises means for detecting a frame synchronization word, and the communication quality is determined based on an error between the received and detected frame synchronization word and an ideal frame synchronization word. Since the determination is made, the communication quality can be determined accurately and promptly, and the deviation correction signal can be transmitted accurately.
According to a fourth aspect of the present invention, in the wireless communication device according to the second aspect, when the deviation of the transmission unit is corrected in response to the deviation correction signal received from the counterpart wireless communication device, the passage of a preset time is measured. Because it has timer means and means to reset the corrected correction when the set time has passed, in order to return the deviation correction to the original state when the start and end of transmission are not clear as in voice communication Can be accurately performed.
The inventions according to claims 5 to 7 relate to a method for controlling a radio communication device, and the functions of the radio communication device according to claims 1 to 4 are configured as processing methods. It can be realized as software means.

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. However, the components, types, combinations, shapes, relative arrangements, and the like described in this embodiment are merely illustrative examples and not intended to limit the scope of the present invention only unless otherwise specified. .
Before describing a specific example of the present invention, the result of verifying the relationship between deviation error and reception sensitivity will be described. FIG. 1 shows the relationship between the variation of the maximum deviation value and the RF (high frequency) signal level required to obtain the same reception quality (reception sensitivity). When the deviation error is 0, it is about −121 dBm. It is shown that. As shown in FIG. 1, it is clear that the higher the deviation error, the higher the reception level (RF reception level: dBm) of the high frequency signal required to obtain the same communication quality, that is, the reception sensitivity decreases. is there. Furthermore, the fact that should be particularly noted with respect to FIG. 1 is that the deviation error to the minus side is more markedly lower than the plus error. For example, the RF reception level with respect to a deviation of −250 Hz is −111 dBm, and an input of a large RF signal of about 10 dB with respect to an error of 0 is necessary, and the reception sensitivity is lowered correspondingly. In addition, it can be seen that the occurrence of an error on the plus side improves the reception sensitivity up to about +150 Hz.
The present invention is based on the relationship between the deviation error and the reception sensitivity. By actively utilizing this phenomenon, the deviation error is corrected automatically or manually while operating the radio communication device. Provided are a wireless communication device configured to always maintain sensitivity in the best state and a control method thereof.

FIG. 2 is a flowchart for explaining the basic concept of the present invention. In this example, a base station radio communication device with relatively stable deviations and a mobile station radio communication device with severe environmental conditions such as temperature changes and large vibrations and high possibility of deviation fluctuations are taken as examples. The present invention will be described. FIG. 2 shows the operation of the base station radio communication apparatus on the left side and the operation of the mobile station radio communication apparatus on the right side, and the two operate in relation to each other. First, when the mobile station transmits to the base station (Sm1), the base station receives this signal (Ss1) and detects the reception quality (Ss2). As a result, when the communication quality falls below a preset threshold value (Ss3 Yes), a deviation correction signal is transmitted to the mobile station (Ss4). When the mobile station receives this signal (Sm2), it corrects the deviation of the transmitter of its own station in a direction increasing by a preset amount (Sm3), and transmits again with the increased deviation (Sm4). If this signal is received by the base station, the reception quality detection and the threshold value are compared again as described above (Ss1 to Ss3), and if the reception quality exceeds the threshold value (Ss3 No), the reception preparation is completed. Is transmitted to the mobile station (Ss5), the mobile station receiving this signal (Sm5) performs data transmission (Sm6), and when the data transmission is completed, the corrected deviation is reset to the original state (Sm7). The process is terminated. Although illustration is omitted, if the reception quality does not exceed the threshold even if the deviation is increased by the processes of Ss1 to Ss4, it is determined that the electric field strength is smaller than the communication quality improvement effect according to the present invention. Then, the increased deviation is reset and the process is terminated.
In addition, the reception quality can be detected by a received signal strength detection means (Receive Signal Strength Indicator: RSSI), or if the relationship between RSSI and the actual electric field strength level is known, instead of reception quality detection, It may be detection of electric field strength.

As described above, when the reception quality is less than or equal to the threshold value, there is a possibility that the deviation on the mobile station side is lowered. Therefore, the deviation correction signal is transmitted from the base station, and the deviation of the mobile station is set at, for example, a 50 Hz step. Perform incremental processing. Then, as described with reference to FIG. 1, the reception quality on the base station side is improved by the reception sensitivity improvement effect due to the increase in the deviation. This reception quality improvement effect is useful not only when the deviation of the transmitter on the mobile station side is lowered, but also when the reception quality is below the threshold due to the low incoming field strength to the base station. In general, since the base station transmission power is often set larger than the mobile station, the base station radio field reception field strength at the mobile station is sufficient, but both the reverse direction base station reception field strength is low, so both In view of the fact that the above-mentioned communication often does not hold, it can be understood that the effect of the present invention enables communication in an area where communication has been impossible in the past. In that case, instead of “communication quality detection” and “communication quality comparison” in the processes Ss2 and Ss3 shown in FIG. 2, “electric field intensity detection” and “electric field intensity comparison” may be performed.
In the above embodiment, the case where the deviation correction is automatically executed when the deviation correction signal is received is described. However, instead of this example, the beep sound, the LED blinking, and the liquid crystal display indicate that the deviation correction signal has been received. It is also possible to notify the operator by a display or the like to prompt the operator to correct the deviation. In this case, a deviation correction start switch is provided, or a deviation correction is performed by a keyboard operation.

3 and 4 are flowcharts showing processing functions of the base station radio communication apparatus and the mobile radio communication apparatus according to a modified embodiment of the present invention. The example shown in FIG. 2 shows an example in which the deviation correction process is repeated a plurality of times until the communication quality and the received electric field strength exceed the threshold. However, in order to simplify the process and perform a quick communication, the deviation correction is performed once. It can also be configured to perform processing. That is, as shown in FIG. 3, when the transmission start message is received from the mobile station (Ss11), the reception quality is detected (Ss12). As a result, when the communication quality is lower than the preset threshold (Ss12 Yes), A reception completion message is transmitted to the mobile station together with the deviation correction signal (Ss13), and data transmitted from the mobile station is received (Ss14). If the received electric field strength exceeds the threshold value in the determination in step Ss12, Only the reception preparation completion message is transmitted to the mobile station (Ss15), and the process proceeds to data reception (Ss14).
Similarly, in the mobile station wireless communication device, as shown in FIG. 4, after receiving the transmission start message (Sm11), when the reception preparation completion message is received from the base station (Sm12 Yes), a deviation correction message is included at the same time. (Sm13 Yes), if it is included (Sm13 Yes), the deviation of the transmitter of the local station is corrected in the direction of increasing the preset amount (Sm14), and the increased deviation Although data transmission is performed (Sm15), if a deviation correction message is not included (Sm13 No), data transmission is performed without performing deviation correction (Sm15). Although not shown in FIG. 4, the corrected deviation is reset after the data transmission is completed. Also in this example, not only the electric field strength comparison but communication quality detection and threshold comparison may be used.

In the case of a wireless communication device having a frame synchronization word (FSW) detection means instead of an electric field strength level and communication quality, the deviation between the detected value and the ideal value at the symbol point of the FSW is determined as the necessity determination of the deviation correction. It is also possible to make a judgment based on a comparison between the calculated value and a preset threshold value. That is, when the ideal symbol value of FSW is Xfs and the received symbol value is X, the error Y between the ideal symbol value and the received symbol value is
Yi = Xfsi−Xi (where i is from 0 to N) (1)
It is expressed as If the number of FSW symbols is N and the error average is Xa,
Xa = (1 / N) ΣYi (where i is from 0 to N) (2)
Therefore, the error variance is σ ² = (1 / N) Σ (Yi−Xa) ² (where i is from 0 to N) (3)
The larger the variance value σ ² , the larger the error from the ideal value, and the communication quality can be evaluated. Therefore, the above formula is calculated, and when the variance value σ ² is compared with a preset threshold value, a deviation correction signal is transmitted when the variance value becomes larger than a certain value.

FIG. 5 is a process flowchart of the base station radio communication apparatus showing a modification of the present invention including such processes. In FIG. 5, when the transmission start message is received from the mobile station (Ss21), the above-described dispersion value σ ² is calculated and compared with a preset threshold value. If the threshold value is exceeded (Ss22 Yes), with deviation correction signal, and transmits a reception preparation completion message (SS23), but receives the data transmitted from the mobile station (SS24), the decision in the process SS22, reception ready If the variance sigma ² below the threshold Only the message is transmitted to the mobile station (Ss25), and the process proceeds to data reception (Ss24). As described above, since the FSW detection is frequently performed in the wireless communication device having the FSW detection function, it can be used for determining whether or not the deviation correction is necessary in the present invention.

FIG. 6 is a process flowchart showing still another embodiment of the present invention, which is a preferred embodiment for a mobile station radio communication apparatus that performs voice communication. That is, in the example shown above, the processing in the data communication has been mainly described. However, in the data communication, the start and the end are often relatively clear, whereas in the voice communication, the start and the end are unclear. In many cases, the timing for resetting the corrected deviation tends to be difficult to grasp. Therefore, the mobile station wireless communication device is provided with a timer function for measuring a predetermined time, and the deviation correction is reset when a predetermined time has elapsed.
In FIG. 6, when the process starts, first, transmission is performed from the mobile station radio to the base station (Sm21), and then a signal transmitted from the base station is received in response (Sm22). Since the base station reply includes a deviation correction signal if necessary based on the signal reception result from the mobile station as described above, the presence / absence of the deviation correction signal is detected (Sm23). Is included (Sm23 Yes), deviation correction is performed (Sm24), and a timer for measuring a certain time is started (Sm25). When a predetermined time has elapsed (Sm26 Yes), the corrected deviation is reset and returned to the original value (Sm27), and the process is terminated.

  Note that if transmission is performed during timer measurement (when the timer time has not expired), transmission is performed with deviation correction. If transmission is performed after the timer has expired, transmission is performed without deviation correction. For example, the process returns to the process Sm21, and the process of Sm27 is repeated. Preferably, if a time slightly longer than the average call time per time is set as the timer time, a call in a state in which the deviation correction is performed can be performed during one call without any trouble. According to this method, there is an effect of preventing transmission in an unnecessary deviation correction state when the start and end are unclear as in voice communication.

  The present invention is not limited to the above-described embodiments, and various modifications can be made. Further, in the embodiment, the case where one is a base station wireless communication device and the other is a mobile station wireless communication device is shown, but it is not necessary to limit to this relationship, communication between mobile station wireless communication devices, base station Any combination of communication between the two or a communication between the repeater and the mobile station is applicable. Furthermore, in both wireless communication devices, the other party's deviation is monitored, or the field strength and the reception quality are monitored. It can also be configured to transmit a signal.

  It should be noted that various configurations of the wireless communication device for realizing the present invention can be considered, and in recent years, since many digital wireless communication devices are used, a program is constructed so as to realize the above-described functions. Then, it can be realized by software by installing it in the memory of a wireless communication device equipped with a CPU. FIG. 7 is a block diagram showing a configuration example of a wireless communication device for realizing the present invention. The configuration shown in this example is displayed as a functional block. The antenna 1, the antenna duplexer 2 for sharing the antenna for transmission and reception, the reception high-frequency unit (RX) 3, the detection circuit 4, the data demodulation unit 5, Frame synchronization word (FSW) detection unit 6, reception quality detection unit 7, threshold memory 8 that stores a preset threshold value, comparator 9 that compares the detected reception quality result with a value in threshold memory 8, and deviation correction A signal generation circuit 10 and a message detection circuit 11 are provided. The transmission side includes a transmission power amplification unit (TX) 12, an FM or PM modulator 13, a data input terminal 14 attached to the FM / PM modulator 13, a microphone 15, a deviation correction circuit 16, and a timer circuit 17. Yes. Among these configurations, what should be noted is that the reception quality evaluation information detected on the basis of the signal of the detection circuit of the reception unit or the FSW detection unit 6 as described above is compared with the value of the threshold memory 8, As a result, a signal from the deviation correction signal generation circuit 10 is supplied to the transmitter, and a message detection that detects a deviation correction signal transmitted from another wireless communication device, a reception preparation completion message, etc. For example, the deviation correction circuit 16 of the transmission unit is started by the output of the circuit 11 and the deviation correction circuit is reset by the timer circuit 17.

In this example, the configuration example including both the transmission-side function and the reception-side function is shown. However, the base station radio device only needs to have a communication quality judgment function and a deviation correction signal transmission function. If the radio for a radio is provided with a deviation correction function, a message detection function, and a timer function, the function of the present invention can be satisfied for at least one-way communication. The means described in Patent Document 1 proposed by the same applicant as a conventional example is disclosed as a deviation adjusting means in the modulation circuit, and can be referred to when implementing the present invention.
Further, since the individual blocks and their functions have already been described in connection with the embodiments, further detailed description is omitted, but the functions of each block are built in (not shown). As described above, the present invention can be realized by installing and executing software constructed as a program.

The graph of the measurement result which shows the relationship between the deviation error and reception sensitivity utilized in this invention. The flowchart which shows one embodiment of the process of the radio | wireless communication apparatus which concerns on this invention. The flowchart which shows the other Example of the process of the radio | wireless communication apparatus which concerns on this invention. The flowchart which shows the other Example of an embodiment of the radio | wireless communication apparatus which concerns on this invention. The flowchart which shows the other Example of an embodiment of the radio | wireless communication apparatus which concerns on this invention. The flowchart which shows the other Example of an embodiment of the radio | wireless communication apparatus which concerns on this invention. The block diagram which shows one Example of the radio | wireless communication apparatus which concerns on this invention. The graph which shows the relationship between a deviation error and a bit error rate.

Explanation of symbols

  3 reception high frequency unit, 4 detection circuit, 5 data demodulation unit, 6 frame synchronization word (FSW) detection unit, 7 reception quality detection unit, 8 threshold memory, 9 comparator, 10 deviation correction signal generation circuit, 11 message detection circuit, 12 transmission power amplifier (TX), 13 message detection circuit, 16 deviation correction circuit, 17 timer circuit.

Claims (7)

  In a wireless communication device having a frequency / phase modulation transmission unit and a reception unit, means for detecting the electric field strength level or reception quality of the received signal received from the counterpart wireless communication device and comparing the result with a preset threshold value And a means for transmitting a deviation correction signal to the counterpart wireless communication device when the field intensity level or reception quality of the compared received signal falls below a threshold value.   When a deviation correction signal is received from a counterpart wireless communication apparatus in a wireless communication apparatus having a frequency / phase modulation type transmission unit and reception unit, means for notifying that fact or automatically correcting the deviation of the transmission unit A wireless communication device comprising means.   2. The wireless communication device according to claim 1, further comprising: means for detecting a frame synchronization word transmitted from the counterpart wireless communication device; and means for detecting an error between the received and detected frame synchronization word and an ideal frame synchronization word. A wireless communication device comprising: means for comparing the detected error with a preset threshold value; and means for transmitting a deviation correction signal to the counterpart wireless communication device when the error is larger than the threshold value.   3. The wireless communication device according to claim 2, wherein when the deviation of the transmission unit is corrected in response to the deviation correction signal received from the counterpart wireless communication device, timer means for measuring the passage of a preset time, and the set time A wireless communication device comprising means for resetting a corrected deviation when it has elapsed.   In a wireless communication device control method when a wireless communication device having a frequency / phase modulation transmission unit and a reception unit communicate with each other, the field strength level or reception quality of a received signal received from the counterpart wireless communication device is detected. Processing, processing for comparing the result with a preset threshold, processing for transmitting a deviation correction signal to the counterpart wireless communication device when the field strength level or reception quality of the compared received signal falls below the threshold, and counterpart wireless communication A control method for a wireless communication device, comprising: a process of notifying that when a deviation correction signal is received from an apparatus, or a process of automatically correcting a deviation of a transmission unit.   6. The method of controlling a wireless communication device according to claim 5, further comprising: detecting a frame synchronization word transmitted from the counterpart wireless communication device, and detecting an error between the received and detected frame synchronization word and an ideal frame synchronization word. And a process for comparing the detected error with a preset threshold value and a process for transmitting a deviation correction signal to the partner radio communication apparatus when the error is greater than the threshold value. Method.   The method of controlling a wireless communication device according to claim 5 or 6, wherein when the deviation of the transmission unit is corrected in response to the deviation correction signal received from the counterpart wireless communication device, a timer process for measuring the elapse of a preset time; A method for controlling a wireless communication device, comprising: a process of resetting a corrected deviation when a set time has elapsed.

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