JP2007129435A - Error detecting device and reception error judging method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an error detecting device and a reception error judging method that can prevent wrong reception and effectively judge received data. <P>SOLUTION: A frame continuation signal 108 is generated in timing 104 based upon the length of the received data, and RSSI data 114 measured by an RSSI measurement section 110 is input to a carrier presence/absence judgement section 116, which compares the RSSI data with an RSSI threshold and generates a carrier presence/absence signal corresponding to the comparison result. A received data length error judgement section 124 generates a received data length error signal 130 based upon those frame continuation signal 108 and carrier presence/absence signal 122 and outputs the signal. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an error detection apparatus and a reception error determination method for detecting an error of a reception signal in a digital radio apparatus that receives a radio signal.

  Digital radio apparatuses generally use a CRC (Cyclic Redundancy Check code) that performs frame error determination in order to ensure the quality of a radio channel.

  In the CRC, transmission data is processed on the transmission data using a predetermined generator polynomial, and the result is added as a redundant code to the data string and transmitted. Next, on the receiving side, the received data is calculated with a generator polynomial determined in advance by the same processing as that on the transmitting side. When the processing result is other than all “0”, it is determined as a data error. In this case, the CRC calculation target is the length indicated by the Length field included in the received data in the payload data portion. Generally, the value of the Length field represents the number of octets of payload data (1 octet = 8 bits).

  The TDMA-TDD system base station synchronization apparatus described in Patent Document 2 terminates the CRC determination bit in a burst frame in order to prevent malfunction due to fluctuations in received electric field strength and to reduce reception errors. In some cases, the detection signal of the received electric field signal is masked by the mask means for a certain period, and the synchronization means of the base station is triggered at the edge timing of the output of the mask means.

  In Patent Document 3, the received digital signal is deteriorated based on the RSSI signal indicating the received intensity of the received signal, the UW signal indicating whether synchronization is established, and the BER signal indicating the error rate of the received digital signal. A digital wireless receiver is disclosed that mutes the output if it is degraded.

JP 2000-252945 A Japanese Patent Laid-Open No. 11-163842 Japanese Patent Laid-Open No. 2000-174643

  However, in the digital radio apparatus using the above-mentioned CRC, if an error occurs in the Length field due to a radio-specific random error, it is erroneously received without an error in the CRC judgment under the following conditions, and the line quality is degraded. was there.

  As the condition, there is a case where the length of the frame is erroneously larger than the expected value and all the data is 0 data for the number of octets having the wrong difference. For example, it is considered that the expected value of 6 octets of Length is received by mistakenly assuming that Length is 8 octets, and all the last 2 octets (8−6 = 2) are received as “0” and processing is judged. It is done.

  The reason for this is that the CRC judgment target is determined by the Length field, but in the case of the above condition, 0 continuation is added after the redundant code of the CRC calculation result added on the transmission side. As a characteristic of the CRC function, the CRC calculation result becomes “0”, and further calculation (division) of 0 data becomes “0” after that, resulting in a determination result without error. However, since the received data has 0 data added to the regular frame (the number of error octets in the Length field), it becomes completely different data and is erroneously received.

  In Patent Document 1, the predicted maximum payload length and the predicted minimum payload length are calculated, and whether or not there is an error in the payload length by comparing the predicted predicted payload length with the payload length information from the received signal is extracted. It was something to do. This method requires a configuration for calculating the predicted payload length and is complicated, and also requires time for calculating the predicted payload length, resulting in a problem that the high speed is reduced. Further, it is conceivable that an error in the payload length that is within the range of the predicted payload length cannot be detected.

  An object of the present invention is to provide an error detection device and a reception error determination method that can prevent such erroneous reception and can determine reception data effectively.

  In order to solve the above-described problem, the present invention provides an error detection apparatus for detecting an error of a received signal received by a digital radio apparatus that receives a radio signal including a plurality of payloads. A timing unit that generates an instruction signal for instructing measurement of strength and generates a frame continuation signal corresponding to the length of the payload (Length) from the received signal, and a measurement that measures the reception intensity of the received signal according to the instruction signal A carrier determination unit that determines presence / absence of a carrier of the radio signal based on the reception strength and generates a carrier presence / absence signal indicating the presence / absence of the carrier, and a payload of the reception signal based on the frame continuation signal and the carrier presence / absence signal Error determination means for determining whether or not there is an error in the length.

  In order to solve the above-mentioned problem, the present invention provides a reception error determination method for detecting an error in a received signal received by a digital radio apparatus that receives a radio signal including a plurality of payloads. Generates an instruction signal for instructing the measurement of the received signal strength in accordance with the timing step for generating a frame continuation signal corresponding to the length of the payload from the received signal, and indicates the received signal strength A measurement step for measuring according to the signal, a carrier determination step for determining the presence / absence of a carrier of the radio signal based on the received intensity, and generating a carrier presence / absence signal indicating the presence / absence of the carrier, and a frame continuation signal and a carrier presence / absence signal And an error determination step of determining whether or not there is an error in the length (Length) of the payload of the received signal.

  According to the present invention, by generating an instruction signal for instructing measurement of reception intensity (RSSI) of a received signal, and generating a frame continuation signal corresponding to the length (Length) of the payload from the received signal, From the carrier presence / absence signal generated by recognizing the frame continuation signal and further determining the presence / absence of the carrier of the radio signal, it can be determined whether or not there is an error in the length (Length) of the payload of the received signal.

  As described above, the present invention generates a carrier presence / absence signal according to whether or not a predetermined threshold or more based on the RSSI measurement result, generates a digital information frame continuation signal generated from the received signal, By comparing the two generated signals, it is possible to detect whether there is an error in the length of the payload obtained from the received signal. Further, the presence / absence of the carrier can be determined by comparing the first parameter with the reception intensity, and the first parameter can be set from the host device.

  Therefore, it is possible to detect erroneous reception by prioritizing and using the received data length error signal even when the CRC is determined to be normal even though the Length field is erroneously generated. Become. Therefore, there is an effect of ensuring the line quality as the system of the digital radio apparatus and improving the reliability.

  Furthermore, the RSSI data being received can be monitored, a level fluctuation equal to or greater than a threshold value can be determined, and the presence of an interference wave in the received IF signal can be detected. In addition, the determination of the level fluctuation equal to or greater than the threshold can be made by comparing the second parameter with the reception intensity, and the second parameter can be set from the host device. Therefore, for example, by changing the channel according to the judgment of the host device, there is an effect of eliminating the adverse effect of the interference wave and improving the line quality of the system.

  Next, embodiments of an error detection device and a reception error determination method according to the present invention will be described in detail with reference to the accompanying drawings. Referring to FIG. 2, there is shown an embodiment of an error detection circuit 10 in a digital radio apparatus to which an error detection apparatus and a reception error determination method according to the present invention are applied. In the following description, portions that are not directly related to the present invention are not shown and described, and the reference numerals of the signals are represented by the reference numbers of the connecting lines that appear.

  The error detection circuit 10 in this embodiment includes a reception length register unit 100 that receives reception data (RXD) 12 obtained by demodulating an intermediate frequency signal (IF signal) and sets a reception payload length. The reception Length register unit 100 outputs the register value 102 to the timing unit 104. In the figure, the reception circuit and the transmission circuit such as a CRC inspection circuit and a demodulation circuit are not shown.

  The timing unit 104 has a function of outputting to the output 106 a register value 102 of the received Length register unit 100 and a measurement instruction signal indicating an instruction to measure RSSI (received electric field strength) in octets of the payload. In addition, the timing unit 104 generates a frame continuation signal indicating frame continuation of received data based on a Length value (received payload length) that is payload length information obtained from the received data 12, and outputs it as a frame continuation signal 108 Have The frame continuation signal 108 represents a frame length corresponding to the recognized Length value at a high level “1” for a period corresponding to the recognized Length value.

  The RSSI measurement unit 110 connected to the output 106 of the timing unit 104 performs RSSI measurement based on the input IF signal 112 and outputs the RSSI data 114.

  The output of the RSSI measurement unit 110 is connected to one input of the carrier determination unit 116 via a connection line 114. The carrier determination unit 116 is a functional unit that determines the presence or absence of a transmission carrier based on the RSSI data 114 and the register value 118 of the RSSI level threshold value register unit 120 connected to the other input. The RSSI level threshold value register unit 120 holds an RSSI level threshold value to determine a transmission carrier, and supplies the register value 118 to the carrier determination unit 116 as a parameter. Carrier determination section 116 supplies carrier presence / absence signal 122 indicating the determination result to reception data length error determination section 124.

  The reception data length error determination unit 124 is a determination unit that determines an error in which the reception data length is inconsistent based on the carrier presence / absence signal 122 and the frame continuation signal 108. When the reception data length error determination unit 124 determines that there is an error in the reception data length, it outputs a significant reception data length error signal 130.

  With the above configuration, the operation of the error detection circuit 10 in the present embodiment will be described with reference to the timing chart for detecting the received data length error shown in FIG.

  First, the Length value (reception payload length) from the reception data (RXD) 12 received from time t1 is stored in the reception Length register unit 100 (time t2 to time t3).

  The timing unit 104 outputs a measurement instruction signal 106 to the RSSI measurement unit 110 for each octet of payload data reception to instruct RSSI measurement. In addition, the timing unit 104 sends a frame continuation signal 108 to the reception data length error determination unit 124 from the start of the reception payload section.

  The RSSI measurement unit 110 sends RSSI data 114 to the carrier determination unit 116 for each octet. The carrier determination unit 116 compares the register value 118 set in the RSSI threshold value register unit 120 by the higher-level device with the RSSI data 114 to determine the presence / absence of a carrier. Carrier determination section 116 transmits carrier presence / absence signal 122 corresponding to the determination result to reception data length error determination section 124. The reception data length error determination unit 124 checks the frame continuation signal 108 supplied from the timing unit 104 and the carrier presence / absence signal 122 supplied from the carrier presence / absence determination unit 116. In this case, reception data length error determination section 124 outputs reception data length error signal 130 when it detects a contradiction when frame continuation is indicated even though there is no transmission carrier (time t4).

  As described above, according to the first embodiment shown in FIGS. 1 and 2, the received data is received even when the CRC is determined to be normal although the Length field is erroneously generated and the Length error is generated. Since an error can be generated by outputting a long error signal, erroneous reception can be detected. Therefore, there is an effect of ensuring the line quality as the system of the digital radio apparatus and improving the reliability.

  Referring to FIG. 3, an example of transmission data and reception data when erroneous reception is performed in a state where a Length error occurs and it is determined that there is no CRC error is shown in the conventional example.

  As shown in the figure, the low-order (LSB) and high-order (MSB) of the CRC are transmitted by adding a redundant code processed by using a predetermined generator polynomial to the transmission data on the transmission side and adding it to the payload data sequence. . On the receiving side, the received data is calculated with a generator polynomial by the same processing as that on the transmitting side, and when the processing result is other than all “0”, it is determined that there is a data error. In this case, the CRC calculation target is the payload data portion, which is 4 octets in the figure, and the CRC calculation result is 2 octets. This is indicated by the Length field included in the received data (0x06).

  However, there may be an error in the Length field of the received data due to, for example, a random error peculiar to the radio, that the frame Length is larger than the expected value and that the data is all 0 data for the wrong number of octets. And For example, it is conceivable that the expected value of 6 octets of Length is erroneously received as being 8 octets, and all the last 2 octets are received as “0” and processing is determined. The reason for this is that the CRC determination target is determined by the Length field, but in the case of the above condition, 0 continuation is further added after the redundant code of the CRC calculation result added on the transmission side. As a characteristic of the CRC function, even if 0 data is further calculated (divided) after the CRC result is “0” (no error), it becomes “0” and it is determined that there is no error. However, since the received data has 0 data added to the regular frame (the number of error octets in the Length field), it becomes completely different data and is erroneously received. In the illustrated example, since there are no more carriers after the regular transmission data, the generation state of dummy data (d1, d2) in which “0 data” for two octets in which the reception data is indefinite continues is shown. In the case of this conventional example, it is determined that the received data has no CRC error, and the payload data is erroneously received as “0x11, 0x22, 0x33, 0x44, 0xDD, 0x33”.

  In the above-described embodiment, even if such a case occurs, for example, a random error peculiar to radio occurs, and a contradiction when frame continuation is indicated even though there is no transmission carrier is detected. Since reception data length error signal 130 can be output, erroneous reception can be prevented.

  Next, another configuration example of the error detection circuit in the digital radio apparatus to which the digital radio apparatus and the reception error determination method according to the present invention are applied will be described below with reference to FIG.

  As shown in the figure, the error detection circuit 400 in the present embodiment further includes an interference wave presence / absence determination unit 410 and an RSSI level fluctuation threshold value register unit 420 in addition to the configuration of the error detection circuit 10 shown in FIG. Therefore, the configuration similar to the configuration indicated by the same reference numerals shown in FIG.

As shown in FIG. 4, the interference wave presence / absence determination unit 410 is connected to the RSSI measurement unit 110 and inputs RSSI data 114 to determine the presence / absence of interference waves. Further, the RSSI level fluctuation threshold value register unit 420 is a register that holds an RSSI level fluctuation threshold value for determining the presence of an interference wave, and the interference wave presence / absence judgment unit via the connection line 430 using the held parameter as a register value. Output to 410. Interference wave presence / absence determination unit 410 determines the presence / absence of an interference wave in received IF signal 112 based on RSSI data 114 and RSSI level fluctuation threshold value (register value) 430. The interference wave presence / absence determination unit 410 outputs the interference wave detection signal 440 when the interference wave is detected. With the above configuration, the operation of the error detection circuit 400 of the digital radio apparatus in this embodiment is described with reference to the timing chart shown in FIG. While explaining.

  First, the timing unit 104 outputs a measurement instruction signal 106 instructing RSSI measurement unit 110 to perform RSSI measurement for each octet of payload data reception (time t1 to time t7). RSSI measurement section 110 sends RSSI data 114 to interference wave presence / absence determination section 410 and carrier presence / absence determination section 116 for each octet. The interference wave presence / absence determination unit 410 compares the register value 430 of the RSSI level fluctuation threshold register unit 420 set by the host device with the RSSI data 114 to determine the presence / absence of interference waves. In this case, the interference wave presence / absence determination unit 410 outputs an interference wave detection signal 440 indicating the presence of an interference wave (time t6 to time t7) when the presence / absence determination detects that a level fluctuation equal to or greater than the threshold value has occurred.

  As described above, according to the second embodiment shown in FIG. 4 and FIG. 5, in addition to the effect of the first embodiment shown in FIG. By detecting the level fluctuation, it is detected that an interference wave is present in the received IF signal. Therefore, for example, by changing the channel according to the judgment of the host device, there is an effect of eliminating the adverse effect of the interference wave and improving the line quality of the system.

  In addition, although each Example demonstrated above showed the example applied to ensuring the quality of a radio channel by using the reception data length error detection method and the interference wave detection method in the whole digital radio apparatus, specifically, For example, it can be applied to a ZigBee system.

  As described above, in the above embodiment, based on the result of RSSI measurement, the carrier presence / absence signal 122 is generated according to whether or not it is equal to or greater than a predetermined threshold, and the payload length information obtained from the reception data 12 is received by the reception Length register unit. 100, and based on the stored payload length information, the digital information frame continuation signal 108 generated according to the payload length information is generated, and whether the two generated signals continue at the same level in the same period By comparing whether or not there is an error, it is possible to detect whether or not there is an error in the payload length information obtained from the received signal. In this comparison process and payload length error detection, for example, an exclusive OR of two signals is calculated, and when the operation result is “1”, a reception data length error signal 130 can be generated. In addition, in the case of further comprising a configuration for detecting an interference wave using RSSI data 114, in order to avoid an adverse effect due to the interference wave, for example, control is performed so as to obtain a higher quality line quality by changing a communication channel. Is possible.

It is a block diagram which shows the structural example of the error detection circuit in an Example. It is a timing chart which shows the operation | movement at the time of the reception data length error detection in the Example shown in FIG. It is a figure for demonstrating the case where a Length error generate | occur | produces and it receives incorrectly. It is a block diagram which shows the other structural example of an error detection circuit. 5 is a timing chart showing an operation when detecting an interference wave in the embodiment shown in FIG.

Explanation of symbols

10 Error detection circuit
100 Receive Length register
104 Timing section
110 RSSI measurement unit
116 Carrier presence / absence judgment unit
120 RSSI threshold register
124 Received data error judgment section
410 Interference wave presence / absence judgment unit
420 RSSI level fluctuation threshold register

Claims (12)

In an error detection apparatus for detecting an error in a received signal received by a digital radio apparatus that receives a radio signal including a plurality of payloads, the apparatus includes:
A timing means for generating an instruction signal instructing measurement of reception intensity of the received signal according to the received signal, and generating a frame continuation signal according to the length of the payload (Length) from the received signal;
Measuring means for measuring the received intensity of the received signal according to the instruction signal;
Carrier determination means for determining the presence / absence of a carrier of the radio signal based on the reception intensity and generating a carrier presence / absence signal indicating the presence / absence of a carrier;
An error detection apparatus comprising: error determination means for determining whether or not there is an error in the length of the payload of the received signal based on the frame continuation signal and the carrier presence / absence signal . The error detection device according to claim 1, wherein the device includes:
First register means for holding a first parameter as a threshold for determining the presence or absence of the carrier;
The carrier determination unit compares the reception strength with the first parameter, and generates the carrier presence / absence signal according to a result of the comparison.   3. The error detection device according to claim 2, wherein the first register means holds the first parameter set by a host device.   4. The error detection device according to claim 1, wherein the error detection device monitors an interference wave from a level fluctuation of the reception signal based on a reception intensity measured by the measurement device. And an interference wave determining means generates an interference wave detection signal when detecting a level fluctuation of a predetermined value or more. 5. The error detection apparatus according to claim 4, wherein the apparatus includes second register means for holding a second parameter as a threshold value for determining a level variation of the received signal.
The interference detection unit is configured to detect a level fluctuation of a predetermined value or more based on the second parameter.   6. The error detection device according to claim 5, wherein the second register means holds the second parameter set by a host device. In a reception error determination method for detecting an error in a received signal received by a digital radio apparatus that receives a radio signal including a plurality of payloads, the method includes:
A timing step of generating an instruction signal instructing measurement of reception intensity of the received signal according to the received signal, and generating a frame continuation signal according to the length of the payload (Length) from the received signal;
A measuring step of measuring the received intensity of the received signal according to the instruction signal;
A carrier determination step of determining presence / absence of a carrier of the radio signal based on the reception intensity and generating a carrier presence / absence signal indicating the presence / absence of the carrier;
An error determination step for determining whether or not there is an error in the length of the payload of the received signal based on the frame continuation signal and the carrier presence / absence signal; Method. The reception error determination method according to claim 7, wherein the method includes a first register step of holding a first parameter as a threshold for determining the presence or absence of the carrier,
The carrier determination step compares the reception strength with the first parameter, and generates the carrier presence / absence signal according to the result of the comparison.   9. The reception error determination method according to claim 8, wherein the first register step holds the first parameter set by a higher-level device.   9. The reception error determination method according to claim 8, wherein the method includes an interference wave determination step of monitoring an interference wave from a level fluctuation of the reception signal based on the reception intensity measured in the measurement step, An interference wave determination step generates an interference wave detection signal when a level fluctuation of a predetermined value or more is detected. The reception error determination method according to claim 10, wherein the method includes a second register step of holding a second parameter as a threshold for determining a level variation of the reception signal,
The reception error determination method, wherein the interference wave determination step detects a level fluctuation of a predetermined value or more based on the second parameter.   12. The reception error determination method according to claim 11, wherein the second register step retains the second parameter set by a host device.

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