Reception device and detection / determination method

Abstract

A reception device (100) includes a control unit (10) that: with respect to a digital reception signal based on a signal transmitted by a transmission device, performs correlation processing for each carrier frequency correction value that is a candidate for a value to be used in correcting a carrier frequency deviation, said correlation processing being performed on the basis of a signal having a corrected carrier frequency and a spreading code sequence used by the transmission device; detects timing of the largest peak value cyclically on the basis of the signal obtained through the correlation processing; and calculates variation values on the basis of a plurality of pieces of peak timing information indicating a plurality of timings detected cyclically. The reception device also includes is a detection / determination unit (109) that: detects a carrier frequency correction value corresponding to the minimum value among the plurality of variation values corresponding to the plurality of carrier frequency correction values; and determines that the detected carrier frequency correction value is to be used for correcting the carrier frequency deviation.

Description

Receiving device and detection decision method

[0001] The present disclosure relates to a receiving apparatus and a detection decision method.

[0002] In communication systems, there may be a difference between the oscillation frequency of a transmitter and that of a receiver. Furthermore, in mobile communications, the difference between the speeds of the transmitter and receiver generates a Doppler frequency. Due to the influence of the difference in oscillation frequency or the Doppler frequency, a difference may occur between the carrier frequency of a signal transmitted by a transmitter and the carrier frequency assumed by a receiver. In communication systems, in order to receive signals normally, it is necessary to correct the carrier frequency difference and synchronize the carrier frequency. Carrier frequency synchronization is also necessary in spread spectrum communications using direct sequence spread spectrum. A spread spectrum signal synchronous receiver has been proposed (see Patent Document 1). The spread spectrum signal synchronous receiver uses multiple frequency offsets to calculate the frequency offset showing the highest peak value of correlation as carrier frequency deviation information.

[0003] JP 2012-165208 A

[0004] The above technique uses multiple frequency offsets. Here, the value based on the frequency offsets may be referred to as a carrier frequency correction value. The above technique also illustrates a case where the maximum peak value is used. In a noisy environment, noise affects the peak value. For example, the case shown in FIG. 9 is illustrated. Referring to FIG. 9, the vertical axis of the graphs in FIGS. 9(A) and 9(B) represents the correlation value. The horizontal axis of the graphs in FIGS. 9(A) and 9(B) represents time. FIG. 9(A) illustrates a case where the maximum peak value is reduced due to the influence of noise. FIG. 9(B) illustrates a case where the peak value is increased from a small value due to the influence of noise. Thus, when the above technique is used, an incorrect carrier frequency correction value may be detected. Then, the carrier frequency deviation is corrected using the incorrect carrier frequency correction value. Using an incorrect carrier frequency correction value results in signals not being received correctly.

[0005] The purpose of this disclosure is to prevent the use of an incorrect carrier frequency correction value.

[0006] According to one aspect of the present disclosure, there is provided a receiving device, the receiving device including: a control unit that performs a correlation process on a digital received signal based on a signal transmitted by a transmitting device, for each carrier frequency correction value that is a candidate for a value used to correct a carrier frequency shift, based on the signal with the carrier frequency corrected and a spreading code sequence used by the transmitting device, detects timings of periodically maximum peak values ​​based on the signal obtained by the correlation process, and calculates a variation value based on multiple peak timing information indicating the periodically detected multiple timings; and a detection determination unit that detects a carrier frequency correction value corresponding to a minimum value among multiple variation values ​​corresponding to the multiple carrier frequency correction values, and determines to use the detected carrier frequency correction value to correct the carrier frequency shift.

[0007] According to the present disclosure, it is possible to prevent the use of an incorrect carrier frequency correction value.

[0008] 1 is a block diagram showing the functions of a receiving device according to a first embodiment. FIG. 2 is a block diagram showing the functions of a carrier frequency correction unit according to the first embodiment. FIG. 3 is a block diagram showing an example (part 1) of the functions of a peak timing detection unit according to the first embodiment. (A) to (C) are diagrams showing examples of graphs illustrating the relationship between correlation values ​​and time according to the first embodiment. FIG. 4 is a block diagram showing an example (part 2) of the functions of a peak timing detection unit according to the first embodiment. FIG. 5 is a block diagram showing the functions of a receiving device according to a second embodiment. FIG. 6 is a block diagram showing the functions of a receiving device according to a third embodiment. FIG. 7 is a block diagram showing the functions of a receiving device according to a fourth embodiment. (A) and (B) are diagrams showing an example of a case where noise affects a peak value.

[0009] Hereinafter, embodiments will be described with reference to the drawings. The following embodiments are merely examples, and various modifications are possible within the scope of the present disclosure.

[0010] 1 is a block diagram showing the functions of a receiving device according to embodiment 1. The receiving device 100 is a device that executes a detection and determination method. The receiving device 100 includes an analog signal processing unit 101, an A / D conversion unit 102, a carrier frequency correction unit 103, a signal band limiting unit 104, a spreading code sequence generation unit 105, an arithmetic unit 106, a peak timing detection unit 107, a variation calculation unit 108, a detection and determination unit 109, a value detection unit 110, a synchronization detection unit 111, a despreading unit 112, a demodulation unit 113, and an error correction decoding unit 114.

[0011] The carrier frequency correction unit 103 , the signal band limiting unit 104 , the calculation unit 106 , the peak timing detection unit 107 , and the variation calculation unit 108 are included in the control unit 10 .

[0012] Some or all of the analog signal processing unit 101, A / D conversion unit 102, carrier frequency correction unit 103, signal band limiting unit 104, spreading code sequence generation unit 105, calculation unit 106, peak timing detection unit 107, variation calculation unit 108, detection decision unit 109, value detection unit 110, synchronization detection unit 111, despreading unit 112, demodulation unit 113, and error correction decoding unit 114 may be realized by a processing circuit.

[0013] Some or all of the analog signal processing unit 101, A / D conversion unit 102, carrier frequency correction unit 103, signal band limiting unit 104, spreading code sequence generation unit 105, calculation unit 106, peak timing detection unit 107, variation calculation unit 108, detection determination unit 109, value detection unit 110, synchronization detection unit 111, despreading unit 112, demodulation unit 113, and error correction decoding unit 114 may be realized as program modules executed by a processor.

[0014] The analog signal processing unit 101 receives a signal transmitted by a transmitting device. The analog signal processing unit 101 performs amplitude adjustment, frequency conversion, and band limiting on the received signal. In amplitude adjustment, the signal is adjusted to a set amplitude by an amplifier. In frequency conversion, the signal is converted by a mixer into a signal of a predetermined intermediate frequency band. In band limiting, frequency components other than those of the signal in the desired band are suppressed by a bandpass filter.

[0015] The analog signal processing unit 101 outputs the analog received signal obtained by these processes. Note that this analog received signal is a signal in the intermediate frequency band. Here, the analog signal processing unit 101 may convert the received signal into a baseband signal by frequency conversion. When this conversion is performed, the output analog received signal is a signal represented by two axes of complex I and Q components.

[0016] Furthermore, carrier frequency errors, which are errors in frequency conversion, may occur due to the influence of the difference between the oscillation frequency of the transmitting device and the oscillation frequency of the receiving device, or the influence of the Doppler frequency. When a carrier frequency error occurs, a phase rotation component that does not actually exist is added to the analog received signal, distorting the waveform of the analog received signal.

[0017] The A / D converter 102 samples the analog received signal at a predetermined sampling frequency to convert the analog received signal into a digital received signal, which may be expressed as a digital received signal based on a signal transmitted by a transmitting device.

[0018] The carrier frequency correction unit 103 has the following functions. Fig. 2 is a block diagram showing the functions of the carrier frequency correction unit according to embodiment 1. The carrier frequency correction unit 103 has a selection unit 103a, an addition unit 103b, a generation unit 103c, a frequency conversion execution unit 103d, and a control unit 103e.

[0019] The selection unit 103a switches between carrier frequency correction values ​​f1, f2, ..., fn at regular intervals and outputs them. The carrier frequency correction values ​​f1 to fn are candidate values ​​used to correct deviations in the carrier frequency. As will be described later, the regular interval is the period until a variation value is determined. The following explanation will be given for the case where the selection unit 103a outputs carrier frequency correction value f1.

[0020] The adder 103b adds a carrier frequency correction value (e.g., carrier frequency correction value f1) and a fixed component signal for converting an intermediate frequency signal into a baseband signal. As will be described later, after the carrier frequency correction value is determined, the adder 103b may use the value output by the value detector 110. Therefore, the value output by the value detector 110 is not used until the carrier frequency correction value is determined. The generator 103c generates a sine wave signal and a cosine wave signal with frequencies corresponding to the signal obtained by the addition.

[0021] The frequency conversion execution unit 103d performs frequency conversion by multiplying the digital received signal output by the A / D conversion unit 102 by a sine wave signal and a cosine wave signal. This results in a two-axis complex baseband signal. This signal is a complex signal having an I component and a Q component. Here, when the analog signal processing unit 101 is performing processing to convert to a baseband signal, the signal of this fixed component becomes 0. Then, the frequency conversion execution unit 103d performs multiplication of complex number signals. The function of the control unit 103e will be described later.

[0022] Returning to Fig. 1, the signal band limiting unit 104 will be described. The signal band limiting unit 104 attenuates band components above a predetermined threshold of the signal obtained by multiplication. In other words, the signal band limiting unit 104 attenuates high-band components of the signal output by the carrier frequency correction unit 103. This suppresses noise components of the signal. The spreading code sequence generating unit 105 generates a spreading code sequence that is the same as the spreading code sequence used by the transmitting device.

[0023] The calculation unit 106 performs correlation processing based on the signal output from the signal band limiting unit 104 (i.e., the attenuated signal) and the spreading code sequence generated by the spreading code sequence generating unit 105. In the correlation processing, the calculation unit 106 multiplies the signal output from the signal band limiting unit 104 by the spreading code sequence generated by the spreading code sequence generating unit 105. In addition, in the correlation processing, the calculation unit 106 multiplies the signal output from the signal band limiting unit 104 while changing the phase, and adds up the multiplication results for each phase. Furthermore, the addition result is a complex signal having an I component and a Q component, and these I component and Q component are each squared and added up to obtain a uniaxial signal. Note that a correlation value is obtained by the correlation processing.

[0024] The peak timing detection unit 107 periodically detects the timing of the maximum peak value based on the signal obtained by the correlation process (i.e., successive correlation values). In other words, the peak timing detection unit 107 detects the timing of the maximum peak value on a periodic basis. This allows multiple timings to be detected. Here, information indicating the timing of the maximum peak value is called peak timing information. Thus, the receiving device 100 can obtain multiple pieces of peak timing information.

[0025] The peak timing detection unit 107 may have the following functions: Fig. 3 is a block diagram showing an example (part 1) of the functions of the peak timing detection unit according to the first embodiment. The peak timing detection unit 107 has a spreading code sequence length counter unit 107a, a comparator 107b, a first counter holding unit 107c, a selector 107d, and a selected value holding unit 107e.

[0026] The spreading code sequence length counter unit 107a outputs counter values ​​from 0 to L-1 for each cycle. For example, the spreading code sequence length counter unit 107a outputs counter values ​​from 0 to L-1 in the first cycle. The spreading code sequence length counter unit 107a outputs counter values ​​from 0 to L-1 in the second cycle.

[0027] The comparator 107b compares the correlation value indicated by the signal obtained by the correlation processing with the peak value held by the selection value holder 107e. The comparator 107b outputs the comparison result to the selector 107d. If the correlation value is greater than the peak value held by the selection value holder 107e, the selector 107d outputs the correlation value. If the correlation value is equal to or less than the peak value, the selector 107d outputs the peak value. The selection value holder 107e holds the value output from the selector 107d and outputs it to the comparator 107b and the selector 107d. If the correlation value is greater than the peak value held by the selection value holder 107e, the comparator 107b outputs an update signal to the first counter holder 107c.

[0028] The first counter holding unit 107c holds a counter value corresponding to the timing at which the update signal is received. The first counter holding unit 107c outputs the counter value held when the counter value reaches L-1. Note that the selection value holding unit 107e initializes the peak value held by the selection value holding unit 107e to 0 when the counter value reaches L-1.

[0029] The variation calculating unit 108 calculates the variation value based on multiple pieces of peak timing information. For example, the variation calculating unit 108 calculates a variance as the variation value based on multiple pieces of peak timing information. Also, for example, the variation calculating unit 108 calculates a standard deviation as the variation value based on multiple pieces of peak timing information. Also, for example, the variation calculating unit 108 calculates, as the variation value, the result of adding up the absolute value of the difference between one piece of peak timing information and the average of the multiple pieces of peak timing information by the number of pieces of peak timing information. Note that this calculation method can reduce the amount of calculation required for the variance and standard deviation.

[0030] In this way, the variation value corresponding to the carrier frequency correction value f1 output by the selection unit 103a is calculated. The receiving device 100 performs the same process using the carrier frequency correction values ​​f2, ..., fn. As a result, the variation value corresponding to each of the carrier frequency correction values ​​f2, ..., fn is calculated. Therefore, the receiving device 100 can obtain a variation value for each carrier frequency correction value. In other words, the receiving device 100 can obtain multiple variation values ​​corresponding to the carrier frequency correction values ​​f1 to fn.

[0031] Here, if an accurate carrier frequency correction value is selected, the maximum peak values ​​occur at the same timing. Therefore, for example, if an accurate carrier frequency correction value is selected, the variance value will be close to 0. Therefore, the detection determination unit 109 detects the carrier frequency correction value corresponding to the smallest value among the multiple variation values ​​corresponding to the carrier frequency correction values ​​f1 to fn. Here, an example of a graph showing the relationship between the correlation value corresponding to multiple carrier frequency correction values ​​and time is shown.

[0032] 4A to 4C are diagrams showing examples of graphs illustrating the relationship between correlation values ​​and time in the first embodiment. The vertical axis of the graphs in FIGS. 4A to 4C represents correlation values. The horizontal axis of the graphs in FIGS. 4A to 4C represents time. FIG. 4A is a graph showing the relationship between correlation values ​​corresponding to carrier frequency correction value f1 and time. FIG. 4B is a graph showing the relationship between correlation values ​​corresponding to carrier frequency correction value f2 and time. FIG. 4C is a graph showing the relationship between correlation values ​​corresponding to carrier frequency correction value f3 and time.

[0033] 4A to 4C, the timing of the maximum peak value detected in each cycle is indicated by an arrow. For example, the detection determination unit 109 detects the carrier frequency correction value f2 corresponding to the smallest value among the plurality of variation values ​​corresponding to the carrier frequency correction values ​​f1 to f3.

[0034] The detection determination unit 109 determines to use the detected carrier frequency correction value to correct the deviation of the carrier frequency, and outputs information indicating the determined carrier frequency correction value to the carrier frequency correction unit 103.

[0035] Here, the control unit 103e of the carrier frequency correction unit 103 will be described. The control unit 103e outputs a signal to the selection unit 103a to cause the selection unit 103a to select the determined carrier frequency correction value. As a result, after the carrier frequency correction value is determined, the selection unit 103a selects the determined carrier frequency correction value and outputs the selected carrier frequency correction value to the addition unit 103b. For example, when the carrier frequency correction value f2 is determined, the selection unit 103a selects the carrier frequency correction value f2 and outputs the carrier frequency correction value f2 to the addition unit 103b. When the value detection unit 110 outputs a value, the addition unit 103b adds the value, the carrier frequency correction value, and a fixed component signal for converting the intermediate frequency signal to a baseband signal. The processing of the generation unit 103c and the frequency conversion execution unit 103d is the same as the processing described above.

[0036] After the carrier frequency correction value is determined, if a deviation of the carrier frequency occurs, the value detection unit 110 detects a value for correcting the deviation, and outputs the detected value to the addition unit 103b.

[0037] The synchronization detection unit 111 detects the timing of the spreading code sequence based on the signal output from the signal band limitation unit 104. For example, the synchronization detection unit 111 performs correlation processing based on the signal output from the signal band limitation unit 104 and the spreading code sequence generated by the spreading code sequence generation unit 105, and detects the timing at which the maximum correlation value occurs as the timing of the spreading code sequence.

[0038] The despreading unit 112 performs despreading processing on the signal output from the signal band limiting unit 104 based on the timing detected by the synchronization detecting unit 111. For example, the despreading unit 112 generates a spreading code sequence based on a signal indicating the timing, multiplies the spreading code sequence by the signal output from the signal band limiting unit 104, and adds up all the multiplication results for each period of the spreading code sequence. The demodulating unit 113 demodulates the signal output from the despreading unit 112. The error correction decoding unit 114 performs error correction decoding processing on the demodulated signal. In this way, the received signal is reproduced.

[0039] Here, when the carrier frequency correction value is determined based on only one maximum peak value, as in the technique of Patent Document 1, the determined carrier frequency correction value may be incorrect.

[0040] According to the first embodiment, the receiving apparatus 100 determines the carrier frequency offset value based on the variation value, thereby preventing the receiving apparatus 100 from using an incorrect carrier frequency offset value.

[0041] The peak timing detector 107 may also have the following functions: The following description will be given assuming that the selector 103a outputs the carrier frequency correction value f1.

[0042] 5 is a block diagram showing an example (part 2) of the function of the peak timing detector according to embodiment 1. The peak timing detector 107 further includes an offset counter 107f and a second counter holding unit 107g.

[0043] The offset counter unit 107f outputs counter values ​​ranging from K to K-1 for each period. For example, when the spreading code sequence length counter unit 107a outputs 0, the offset counter unit 107f outputs K. Also, for example, when the spreading code sequence length counter unit 107a outputs L-1, the offset counter unit 107f outputs K-1. The second counter holding unit 107g holds a counter value corresponding to the timing at which the update signal is received. The second counter holding unit 107g outputs the counter value it holds when the counter value reaches K-1.

[0044] In this way, the spreading code sequence length counter unit 107a outputs counter values ​​from 0 to L-1 for each period. This output is called an output based on the first criterion. Therefore, the peak timing detection unit 107 periodically detects the timing of the maximum peak value based on the first criterion. Furthermore, the offset counter unit 107f outputs counter values ​​from K to K-1 for each period. This output is called an output based on the second criterion. Therefore, the peak timing detection unit 107 periodically detects the timing of the maximum peak value based on the second criterion.

[0045] Here, the plurality of peak timing information output from the first counter holding unit 107c is referred to as a plurality of first peak timing information, and the plurality of peak timing information output from the second counter holding unit 107g is referred to as a plurality of second peak timing information.

[0046] The variation calculation unit 108 calculates a variation value based on a plurality of pieces of first peak timing information.The variation calculation unit 108 calculates a variation value based on a plurality of pieces of second peak timing information.

[0047] Here, the variation value based on multiple pieces of first peak timing information may become large. For example, when multiple pieces of first peak timing information indicate values ​​around 0 and L-1, the variation value may become large. In other words, when values ​​around 0 and L-1 are concentrated (i.e., when there are many values ​​around 0 and L-1), the variation value can be said to be small. However, the calculation may result in a large variation value. A specific example will be used for explanation. For example, L is 15. The number of multiple pieces of first peak timing information is 3. For example, the multiple pieces of first peak timing information are 0, 14, and 0. The variation calculation unit 108 calculates a variation value of "43.5", which is the variance, based on 0, 14, and 0. In this way, the variation value may become large. Therefore, the variation calculation unit 108 also uses multiple pieces of second peak timing information. First, when the plurality of pieces of first peak timing information indicate values ​​around 0 and L-1, the plurality of pieces of second peak timing information indicate values ​​around K and K-1. For example, K is set to 8. The number of pieces of second peak timing information is set to 3, as above. For example, the plurality of pieces of second peak timing information are set to 8, 7, and 8. The variation calculation unit 108 calculates a variation value of "0.2", which is the variance value, based on 8, 7, and 8. In this way, the receiving device 100 can obtain a small variation value by using the plurality of pieces of second peak timing information. In other words, the receiving device 100 can obtain a normal variation value.

[0048] In this manner, a variation value corresponding to the carrier frequency correction value f1 based on a plurality of pieces of first peak timing information (hereinafter referred to as the first variation value) and a variation value corresponding to the carrier frequency correction value based on a plurality of pieces of second peak timing information (hereinafter referred to as the second variation value) are calculated. The receiving device 100 performs the same process using the carrier frequency correction values ​​f2, ..., fn. As a result, a first variation value and a second variation value corresponding to each of the carrier frequency correction values ​​f2, ..., fn are calculated. Thus, the receiving device 100 can obtain a first variation value and a second variation value for each carrier frequency correction value. That is, the receiving device 100 can obtain a plurality of first variation values ​​corresponding to the carrier frequency correction values ​​f1 to fn based on a plurality of pieces of first peak timing information and a plurality of second variation values ​​corresponding to the carrier frequency correction values ​​f1 to fn based on a plurality of pieces of second peak timing information.

[0049] The detection decision unit 109 detects a carrier frequency correction value corresponding to the minimum value among a plurality of first variation values ​​corresponding to carrier frequency correction values ​​f1 to fn based on a plurality of first peak timing information and a plurality of second variation values ​​corresponding to carrier frequency correction values ​​f1 to fn based on a plurality of second peak timing information.

[0050] Furthermore, the variation calculation unit 108 may calculate the variation value by excluding, from among the plurality of pieces of peak timing information, the peak timing information that is farthest from the average value of the plurality of pieces of peak timing information. For example, if the plurality of pieces of peak timing information are "a, a+1, a-1, a, a+10, a," the variation calculation unit 108 excludes "a+10" and calculates the variation value based on "a, a+1, a-1, a, a." Note that "a" is a timing within one period. The variation calculation unit 108 may exclude multiple pieces of peak timing information. For example, the variation calculation unit 108 excludes multiple pieces of peak timing information that have a large difference between the peak timing information and the average value. The excluded peak timing information is likely to be erroneously detected peak timing information. Therefore, the receiving device 100 can detect an appropriate carrier frequency correction value by excluding erroneously detected peak timing information.

[0051] Here, the deviation in the carrier frequency may fluctuate due to changes in the position of the transmitting device and the position of the receiving device 100. Therefore, the receiving device 100 may determine the carrier frequency correction value again. The processing will be described in detail. After the carrier frequency correction value is determined, the selection unit 103a switches between and outputs multiple carrier frequency correction values ​​included in a range narrower than the range indicating the multiple carrier frequency correction values ​​at regular intervals. Furthermore, the multiple carrier frequency correction values ​​included in the narrow range include the determined carrier frequency correction value. The processing will be described in detail. Assume that carrier frequency correction value f2 is determined. Furthermore, carrier frequency correction value fn is carrier frequency correction value f10. After carrier frequency correction value f2 is determined, the selection unit 103a switches between and outputs carrier frequency correction values ​​f1 to f3 included in a range narrower than the range indicating the carrier frequency correction values ​​f1 to f10 at regular intervals. In this way, when the receiving device 100 determines the carrier frequency correction value again, it determines the carrier frequency correction value again from within the narrow range. In other words, the receiving device 100 does not determine the carrier frequency correction value from within a range indicating the carrier frequency correction values ​​f1 to fn (i.e., a wide range), so the receiving device 100 can determine the carrier frequency correction value in a short time.

[0052] Second Embodiment Next, a second embodiment will be described. In the second embodiment, differences from the first embodiment will be mainly described. In the second embodiment, descriptions of the commonalities between the first embodiment and the second embodiment will be omitted.

[0053] 6 is a block diagram showing the functions of the receiving device of the second embodiment. The receiving device 100 further includes a signal storage unit 115 and a signal switching unit 116. The signal storage unit 115 may be realized as a storage area secured in a memory. The signal switching unit 116 may be realized by a processing circuit. Furthermore, the signal switching unit 116 may be realized as a program module executed by a processor.

[0054] The signal storage unit 115 stores the digital received signal output by the A / D conversion unit 102. More specifically, the signal storage unit 115 stores a number of digital received signals sufficient to calculate the variation value. While the process of determining the carrier frequency correction value is being performed, the signal switching unit 116 repeatedly outputs the digital received signal stored in the signal storage unit 115 to the carrier frequency correction unit 103 so that the carrier frequency correction value is determined by repeatedly using the digital received signal. After the carrier frequency correction value is determined, the signal switching unit 116 outputs the digital received signal output by the A / D conversion unit 102 to the carrier frequency correction unit 103. In this manner, the signal switching unit 116 switches signals.

[0055] In this way, while the process of determining the carrier frequency correction value is being performed, the receiving device 100 repeatedly uses the same digital received signal to calculate multiple variation values ​​corresponding to multiple carrier frequency correction values. For example, repeatedly using the same digital received signal means the following: The digital received signal used to calculate the variation value corresponding to carrier frequency correction value f1 is the same as the digital received signal used to calculate the variation value corresponding to carrier frequency correction value f2.

[0056] According to the second embodiment, the receiving apparatus 100 calculates the variation value under the same circumstances by using the same digital received signal, which allows the receiving apparatus 100 to improve the accuracy of determining the carrier frequency offset value.

[0057] Furthermore, when the receiving device 100 determines the carrier frequency correction value again, it may use the same digital received signal. However, the digital received signal used in determining the carrier frequency correction value again is a digital received signal obtained after the digital received signal used in determining the carrier frequency correction value. In other words, after determining the carrier frequency correction value, the receiving device 100 deletes the digital received signal stored in the signal storage unit 115, stores a new digital received signal output by the A / D conversion unit 102 in the signal storage unit 115, and uses the new digital received signal in determining the carrier frequency correction value again.

[0058] Embodiment 3 Next, embodiment 3 will be described. In embodiment 3, differences from embodiment 1 will be mainly described. Furthermore, in embodiment 3, descriptions of matters common to embodiment 1 will be omitted.

[0059] 7 is a block diagram showing the functions of a receiving device according to the third embodiment. The receiving device 100 further includes a peak value detecting unit 117 and an aggregating unit 118. The peak value detecting unit 117 and the aggregating unit 118 are included in the control unit 10. The peak value detecting unit 117 and the aggregating unit 118 may be realized by a processing circuit. The peak value detecting unit 117 and the aggregating unit 118 may also be realized as program modules executed by a processor.

[0060] The following description will be given assuming that the selector 103a outputs the carrier frequency correction value f1. The peak value detector 117 periodically detects the maximum peak value based on the signal obtained by the correlation process (i.e., the successive correlation values). In other words, the peak value detector 117 detects the maximum peak value for each period. This allows multiple peak values ​​to be detected.

[0061] The aggregating unit 118 aggregates the multiple peak values. For example, the aggregating unit 118 outputs the average value of the multiple peak values ​​as the aggregation result. Furthermore, for example, the aggregating unit 118 outputs the maximum value or median value of the multiple peak values ​​as the aggregation result.

[0062] The receiving device 100 performs the same process using the carrier frequency correction values ​​f2, ..., fn, so that the receiving device 100 can obtain a plurality of aggregated results corresponding to the carrier frequency correction values ​​f1 to fn.

[0063] The detection determiner 109 divides the aggregated result by the variation value corresponding to the carrier frequency correction value for each aggregated result and the variation value corresponding to the carrier frequency correction value. For example, the detection determiner 109 divides the aggregated result corresponding to the carrier frequency correction value f1 by the variation value corresponding to the carrier frequency correction value f1. Also, for example, the detection determiner 109 divides the aggregated result corresponding to the carrier frequency correction value f2 by the variation value corresponding to the carrier frequency correction value f2.

[0064] The detection determination unit 109 detects the carrier frequency correction value corresponding to the maximum value among the multiple values ​​obtained by the calculation. Note that the multiple values ​​are values ​​obtained by calculation for each carrier frequency correction value. The detection determination unit 109 determines to use the detected carrier frequency correction value to correct the carrier frequency deviation.

[0065] Here, the larger the value indicated by the aggregation result, the more likely it is that the carrier frequency correction value is accurate. Also, the smaller the variation value, the more likely it is that the carrier frequency correction value is accurate. Therefore, the detection determination unit 109 divides the aggregation result by the variation value to determine the carrier frequency correction value used to correct the deviation of the carrier frequency.

[0066] Furthermore, the detection determining unit 109 may execute the following process. When there are multiple carrier frequency correction values ​​(hereinafter, multiple first carrier frequency correction values) corresponding to the minimum value of the variation value among the carrier frequency correction values ​​f1 to fn, the detection determining unit 109 detects the carrier frequency correction value corresponding to the maximum value among the multiple aggregation results corresponding to the multiple first carrier frequency correction values. The detection determining unit 109 determines to use the detected carrier frequency correction value to correct the deviation of the carrier frequency.

[0067] As described above, the larger the value indicated by the aggregation result, the more likely it is that the carrier frequency correction value is accurate. Therefore, when there are multiple first carrier frequency correction values, the detection determining unit 109 detects the carrier frequency correction value corresponding to the maximum value among the multiple aggregation results corresponding to the multiple first carrier frequency correction values.

[0068] In this way, the receiving apparatus 100 can detect a desirable carrier frequency offset value by using both the variation value and the aggregation result.

[0069] Embodiment 4 Next, embodiment 4 will be described. In embodiment 4, differences from embodiments 1 to 3 will be mainly described. Furthermore, in embodiment 4, descriptions of matters common to embodiments 1 to 3 will be omitted.

[0070] 8 is a block diagram showing the functions of a receiving device according to embodiment 4. Embodiment 4 is a combination of embodiments 1 to 3. The receiving device 100 further includes a signal storage unit 115, a signal switching unit 116, a peak value detection unit 117, and an aggregation unit 118.

[0071] While the carrier frequency offset value determination process is being performed, the receiving device 100 repeatedly uses the same digital received signal to calculate multiple aggregation results corresponding to multiple carrier frequency offset values. The detection determination unit 109 determines the carrier frequency offset value based on the multiple variation values ​​and the multiple aggregation results. The determination process is the same as in embodiment 3, so a description thereof will be omitted.

[0072] According to the fourth embodiment, the receiving device 100 can obtain the same effects as those of the second and third embodiments.

[0073] Furthermore, when the receiving device 100 determines the carrier frequency correction value again, it may use the same digital received signal. However, the digital received signal used in determining the carrier frequency correction value again is a digital received signal obtained after the digital received signal used in determining the carrier frequency correction value. In other words, after determining the carrier frequency correction value, the receiving device 100 deletes the digital received signal stored in the signal storage unit 115, stores a new digital received signal output by the A / D conversion unit 102 in the signal storage unit 115, and uses the new digital received signal in determining the carrier frequency correction value again.

[0074] The features of the above-described embodiments can be combined with each other as appropriate.

[0075] 10 Control unit, 100 Receiving device, 101 Analog signal processing unit, 102 A / D conversion unit, 103 Carrier frequency correction unit, 103a Selection unit, 103b Addition unit, 103c Generation unit, 103d Frequency conversion execution unit, 103e Control unit, 104 Signal band limiting unit, 105 Spreading code sequence generation unit, 106 Calculation unit, 107 Peak timing detection unit, 107a Spreading code sequence length counter unit, 107b Comparison unit, 107c First counter holding unit, 107d Selection unit, 107e Selected value holding unit, 107f Offset counter unit, 107g Second counter holding unit, 108 Calculation unit, 109 Detection determination unit, 110 Value detection unit, 111 Synchronization detection unit, 112 Despreading unit, 113 demodulation unit, 114 error correction decoding unit, 115 signal storage unit, 116 signal switching unit, 117 peak value detection unit, 118 aggregation unit.

Claims

1. a control unit that performs correlation processing for a digital received signal based on a signal transmitted by a transmitting device, for each carrier frequency correction value that is a candidate for a value used to correct a shift in a carrier frequency, based on the signal whose carrier frequency has been corrected and a spreading code sequence used by the transmitting device, detects timings of maximum peak values ​​periodically based on the signal obtained by the correlation processing, and calculates a dispersion value based on a plurality of peak timing information indicating the plurality of timings periodically detected; A detection and determination unit that detects a carrier frequency correction value corresponding to a minimum value among a plurality of variation values ​​corresponding to the plurality of carrier frequency correction values, and determines to use the detected carrier frequency correction value to correct a deviation of the carrier frequency; A receiving device having the same.

2. The control unit calculates, as the variation value, a result of adding up an absolute value of a difference between one piece of peak timing information and an average of the plurality of pieces of peak timing information by the number of pieces of the plurality of pieces of peak timing information.

2. The receiving device according to claim 1.

3. the control unit excludes peak timing information that is farthest from an average value of the plurality of peak timing information from the plurality of peak timing information, and calculates the variation value.

2. The receiving device according to claim 1.

4. the control unit periodically detects timings of maximum peak values ​​based on a first criterion, calculates a first variation value based on a plurality of first peak timing information indicating the plurality of periodically detected timings, periodically detects timings of maximum peak values ​​based on a second criterion, and calculates a second variation value based on a plurality of second peak timing information indicating the plurality of periodically detected timings; the detection determination unit detects a carrier frequency correction value corresponding to a minimum value among a plurality of first variation values ​​corresponding to a plurality of the carrier frequency correction values ​​based on a plurality of first peak timing information, and a plurality of second variation values ​​corresponding to a plurality of the carrier frequency correction values ​​based on a plurality of second peak timing information; 4. The receiving device according to claim 1.

5. After the carrier frequency correction value is determined, the control unit again determines a carrier frequency correction value from among a plurality of carrier frequency correction values ​​included in a range narrower than the range indicating the plurality of carrier frequency correction values, The plurality of carrier frequency correction values ​​included in the narrow range includes the determined carrier frequency correction value.

4. The receiving device according to claim 1.

6. A signal storage unit that stores the digital received signal, The control unit calculates the plurality of variation values ​​corresponding to the plurality of carrier frequency offset values ​​by repeatedly using the same digital reception signal while performing the process of determining the carrier frequency offset value.

4. The receiving device according to claim 1.

7. the signal storage unit stores a digital received signal obtained after the digital received signal used in determining the carrier frequency offset value; After the carrier frequency correction value is determined, the control unit again determines a carrier frequency correction value from among a plurality of carrier frequency correction values ​​included in a range narrower than the range indicating the plurality of carrier frequency correction values, The plurality of carrier frequency correction values ​​included in the narrow range includes the determined carrier frequency correction value.

7. The receiving device according to claim 6.

8. The control unit is periodically detecting a maximum peak value based on the signal obtained by the correlation processing, and aggregating the detected multiple peak values; The detection determination unit For each dispersion value and aggregation result corresponding to the carrier frequency offset value, divide the aggregation result by the dispersion value; Detecting the carrier frequency offset value corresponding to the maximum value among the multiple values ​​obtained by the calculation; determining that the detected carrier frequency correction value is used to correct the deviation of the carrier frequency; 4. The receiving device according to claim 1.

9. The control unit periodically detects a maximum peak value based on the signal obtained by the correlation processing, and aggregates a plurality of peak values ​​obtained by the detection, When a plurality of first carrier frequency correction values, which are a plurality of carrier frequency correction values ​​corresponding to a minimum value of the variation value, are present among the plurality of carrier frequency correction values, the detection determination unit detects a carrier frequency correction value corresponding to a maximum value among a plurality of aggregated results corresponding to the plurality of first carrier frequency correction values, and determines to use the detected carrier frequency correction value to correct a deviation of the carrier frequency.

4. The receiving device according to claim 1.

10. The aggregated result is an average value, a maximum value, or a median value of the plurality of peak values.

9. The receiving device according to claim 8.

11. The receiving device: a correlation process is performed on a digital received signal based on a signal transmitted by a transmitting device, for each carrier frequency correction value that is a candidate for a value used to correct a shift in a carrier frequency, based on the signal whose carrier frequency has been corrected and a spreading code sequence used by the transmitting device, the timing of a maximum peak value is periodically detected based on the signal obtained by the correlation process, and a dispersion value is calculated based on a plurality of peak timing information indicating the plurality of timings detected periodically; Detecting a carrier frequency offset value corresponding to a minimum value among a plurality of variation values ​​corresponding to the plurality of carrier frequency offset values; determining that the detected carrier frequency correction value is used to correct the deviation of the carrier frequency; Detection decision method.