Relay device, terminal device, control method, and program for improving position estimation accuracy

Abstract

To improve positioning accuracy in a wireless communication system in which a relay device is used.SOLUTION: The relay device that relays a wireless signal received from a base station device to a terminal device, when receiving a predetermined signal generated using a first series from the base station device, relays to the terminal device a predetermined signal corresponding to a signal generated using a second series corresponding to the first series that is not used when the base station device generates the predetermined signal.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a position estimation technique in a wireless communication system using a relay device. [Background technology]

[0002] In a wireless communication system, by identifying the location of a terminal device, it is possible to provide the terminal device with a communication service according to the location. The terminal device can identify its own location by measuring radio waves transmitted from an artificial satellite using, for example, a Global Navigation Satellite System (GNSS), and notify the network of the information via a base station device. On the other hand, there may be cases where the terminal device is unable to use GNSS-based positioning, or where the GNSS-based positioning function is disabled. In such cases, for example, a method can be used in which the terminal device measures radio waves transmitted from multiple base station devices, and estimates the location of the terminal device based on the timing (propagation time) and direction of arrival of the radio waves. Summary of the Invention [Problem to be solved by the invention]

[0003] In a cellular communication system, in order to increase a communication area, a relay device (e.g., a wireless repeater) may be used that amplifies and outputs radio waves received from a base station device or a terminal device. When a relay device is used, the relay operation within the relay device may lengthen the delay until the radio waves sent from the base station device reach the terminal device. This delay may cause the terminal device to determine that the base station device is located farther away than it actually is, and as a result, the positioning error of the terminal device may become very large. [Means for solving the problem]

[0004] The present invention provides a technique for improving positioning accuracy in a wireless communication system in which a relay device is used.

[0005] A relay device according to one aspect of the present invention includes relay means for relaying a radio signal received from a base station device to a terminal device, and control means for controlling the relay means, when a predetermined signal generated using a first sequence is received from the base station device, to relay to the terminal device a second sequence corresponding to the first sequence, the second sequence being not used when the base station device generates the predetermined signal. When a signal different from the predetermined signal is received from the base station device, the relay means amplifies the signal without demodulating it and transfers it to the terminal device. .

[0006] A terminal device according to one embodiment of the present invention has a detection means for detecting an arriving predetermined signal, and an estimation means for estimating a position of the terminal device based on the detected predetermined signal and the position of a base station device that transmitted the predetermined signal, wherein the estimation means estimates the position of the terminal device using the timing at which the predetermined signal was detected when the predetermined signal generated using a first sequence is detected, and when the estimation means detects the predetermined signal corresponding to a signal generated using a second sequence related to the first sequence and which is not used when the base station device generates the predetermined signal, corrects the timing by a time related to relay processing in a relay device so that the predetermined signal arrives earlier than the timing at which the predetermined signal was detected, thereby estimating the position of the terminal device. Effect of the Invention

[0007] According to the present invention, it is possible to improve the positioning accuracy in a wireless communication system in which a relay device is used. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a wireless communication system. [Diagram 2] FIG. 11 is a diagram illustrating an example of a relay process of a PSS. [Diagram 3] FIG. 2 illustrates an example of a hardware configuration of a relay device and a terminal device. [Figure 4]FIG. 2 illustrates an example of a functional configuration of a relay device. [Diagram 5] FIG. 2 is a diagram illustrating an example of a functional configuration of a terminal device. [Figure 6] FIG. 1 is a diagram illustrating an example of a flow of processing executed in a wireless communication system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims, and not all combinations of features described in the embodiments are essential to the invention. Two or more features among the multiple features described in the embodiments may be arbitrarily combined. In addition, the same reference numbers are used for the same or similar configurations, and duplicated descriptions are omitted.

[0010] (System Configuration) FIG. 1 shows a configuration example of a wireless communication system according to the present embodiment. The wireless communication system may be a cellular communication system conforming to a cellular communication standard such as Long Term Evolution (LTE) or 5th Generation (5G) in which a terminal device connects to a base station device and performs wireless communication. It is assumed that the wireless communication system employs a relay device to improve wireless quality at a cell edge or a blind zone. FIG. 1 shows an example in which base station devices 101 to 103 and a terminal device 111 exist, and a relay device 121 is provided to relay communication of the base station device 103, for example. The terminal device 111 is configured to be able to connect to any of the base station devices 101 to 103 and perform communication. When the terminal device 111 connects to the base station device 103, the terminal device 111 establishes a connection via the relay device 121. It is noted that the relay device 121 may be, for example, a non-regenerative relay device (wireless repeater) that amplifies and outputs an incoming signal without performing demodulation or the like.

[0011] In this wireless communication system, the terminal device 111 detects a predetermined signal transmitted from each of the base station devices 101 to 103, and estimates its own location based on the timing of the detection. The terminal device 111 can estimate its own location based on the respective locations of three or more base station devices (for example, the base station devices 101 to 103) and the difference in timing at which the predetermined signals transmitted from each of these base station devices were detected, that is, the time difference of arrival (TDOA).

[0012] On the other hand, the terminal device 111 receives a predetermined signal sent from the base station device 103 via the relay device 121. For this reason, due to processing delays such as amplification and output by the relay device 121, the time it takes for the predetermined signal sent from the base station device 103 to be received by the terminal device 111 does not correspond to the length of the radio wave propagation path between the terminal device 111 and the base station device 103 via the relay device 121, and the error in the estimation result of the position of the terminal device 111 increases. On the other hand, if the terminal device 111 can recognize that the predetermined signal has arrived at the terminal device 111 via the relay device 121, the reception timing of the predetermined signal at the terminal device 111 can be corrected so that the predetermined signal arrives at the terminal device 111 earlier by the amount of the processing delay in the relay device 121. The timing after this correction corresponds to the length of the radio wave propagation path between the terminal device 111 and the base station device 103 via the relay device 121. In this case, the terminal device 111 may perform location estimation by treating the predetermined signal from the base station device 103 as having directly reached the terminal device 111 at the corrected timing. Also, the terminal device 111 may correct the corrected timing to a timing further advanced by a time corresponding to the distance between the base station device 103 and the relay device 121, and may treat the predetermined signal sent from the relay device 121 as having reached the terminal device 111 at the re-corrected timing. The terminal device 111 may then estimate its own location based on the difference in reception timing of the predetermined signals arriving from the base station device 101, the base station device 102, and the relay device 121, thereby improving the accuracy of location estimation.

[0013] On the other hand, if the relay device 121 is a wireless repeater configured to amplify and transmit an incoming wireless signal without demodulating it, it is not possible to distinguish whether the signal that has arrived at the terminal device 111 has arrived directly from the base station device 103 or has arrived via the relay device 121. For this reason, the terminal device 111 cannot perform appropriate correction of the reception timing. In view of such circumstances, in this embodiment, the processing of the relay device 121 makes it possible to distinguish whether the signal that has arrived at the terminal device 111 has arrived directly from the base station device 103 or has arrived via the relay device 121, and enables the terminal device 111 to perform appropriate correction of the reception timing.

[0014] When the relay device 121 of this embodiment receives a predetermined signal from the base station device 103, it does not amplify and output the signal as it is, but transmits the signal after performing a predetermined process. For example, the predetermined signal transmitted from the base station device 103 is generated using a first sequence. In this case, when the predetermined signal arrives at a predetermined power level or higher, the terminal device 111 can detect the predetermined signal using the first sequence. In this embodiment, the relay device 121 is also configured to detect the predetermined signal using the first sequence. Then, when the relay device 121 receives a predetermined signal generated using the first sequence, it relays a predetermined signal generated using a second sequence that corresponds to the first sequence and is different from the first sequence. Here, the second sequence may be a sequence that is not used when the predetermined signal is transmitted by the base station device 103. According to this, when the terminal device 111 detects a specified signal using the first sequence, it can determine that the specified signal arrived directly from the base station device 103, and when the terminal device 111 detects a specified signal using the second sequence, it can determine that the specified signal arrived via the relay device 121.

[0015] Note that the base station device 103 uses a first sequence when transmitting a predetermined signal, and a sequence that can be used as the first sequence may have multiple patterns. For example, when the predetermined signal is a primary synchronization signal (PSS), the base station device 103 may use a predetermined sequence prepared in advance as the first sequence as is, or may use a sequence obtained by cyclic shifting the predetermined sequence by a predetermined shift amount as the first sequence. Note that a cyclic shift is obtained by changing the head position of a predetermined sequence and adding a partial sequence that exists before the head position to the end of the sequence. For example, by performing a cyclic shift of 10 on a sequence of length 100 in which each symbol is assigned an index of 0 to 99, a sequence whose head position becomes 10 and in which a partial sequence with an index of 0 to 9 is added after the symbol with an index of 99 is obtained. Here, for the PSS, three shift amounts are specified for a Zadoff-chu sequence with a length of 127: (1) no shift (shift amount=0), (2) shift amount=43, and (3) shift amount=86. Therefore, when the PSS is used as a predetermined signal, one of the three sequences corresponding to the shift amounts can be used as the first sequence. In response to this, the relay device 121 can use a sequence different from any of the three sequences as the second sequence. For example, 3×N (N≧1) second sequences corresponding to the three first sequences can be prepared. The relay device 121 can specify which of the three first sequences was used to generate the signal received from the base station device 103, select a sequence to be used from the N second sequences corresponding to the specified sequence, generate a predetermined signal from the selected sequence, and transfer it to the terminal device 111. Note that the second sequence can be a sequence unrelated to the predetermined sequence used when generating the first sequence. Additionally, the second sequence may, in one example, be a sequence that is orthogonal to the predetermined sequence used in generating the first sequence.By preparing second sequences corresponding to each of a plurality of sequences that can be used as a first sequence, it becomes possible to determine to which of a plurality of sequences that can be used as a first sequence a specific signal detected in terminal device 111 corresponds, and also to which base station device transmitted the specific signal.

[0016] As described above, the predetermined signal may be a PSS. In this case, the first sequence is a sequence obtained by cyclic shifting the predetermined sequence by a first shift amount (shift amount=0, 43, or 86) as described above. In this case, the second sequence may be a sequence obtained by cyclic shifting the predetermined sequence by a second shift amount that cannot be taken as the first shift amount. For example, when the first shift amount is 0, the second shift amount associated with the first shift amount may be set to 9, 18, or 27. When the first shift amount is 43, the second shift amount associated with the first shift amount may be set to 52, 61, or 70, and when the first shift amount is 86, the second shift amount associated with the first shift amount may be set to 95, 104, or 113. In this case, for example, (first shift amount+9×N) may be used as the second shift amount (N=1, 2, or 3). The relay device 121 may identify a corresponding second shift amount from the first shift amount corresponding to the received PSS, and generate a new PSS using a sequence corresponding to the second shift amount. In this case, however, the relay device 121 may modify and transmit the newly generated PSS in a format that reflects the reception quality and the like in the received PSS, that is, in a format that does not lose the characteristics of the PSS received from the base station device 103. The relay device 121 may modify the received PSS by performing a cyclic shift of the corresponding shift amount on the received PSS, and transmit a PSS corresponding to the second shift amount without generating a new PSS.

[0017] By detecting a peak of a value calculated by correlation detection using a known sequence, it is detected that a predetermined signal using the known sequence has been transmitted. In contrast, when a different sequence is generated by performing a cyclic shift on a predetermined sequence, when correlation detection is performed on a predetermined signal generated using the different sequence, a peak may occur at a timing shifted by a time corresponding to the shift amount. In this case, if the timing shift at which a peak occurs in correlation detection using a predetermined sequence is included within the range of a cyclic prefix added to one OFDM (orthogonal frequency division multiplexing) symbol, an error may occur in determining which shift amount corresponds to the peak. That is, it is assumed that a certain delayed wave is generated for an OFDM symbol generated by a certain sequence, and therefore a cyclic prefix is ​​added, so when correlation detection is performed using that sequence, a peak corresponding to the delayed wave is detected within the range of the cyclic prefix. On the other hand, when correlation detection is performed using a different sequence obtained by performing a cyclic shift on that sequence, a peak occurs with a shift in timing. At this time, if the amount of cyclic shift is not large enough, the timing shift is not large, and a peak may occur at the same timing as the delayed wave, for example. In this case, it becomes impossible to determine whether the peak that appears corresponds to the sequence before the cyclic shift or the sequence after the cyclic shift. For this reason, in this embodiment, the shift amount can be set so that the difference in the timing at which the peak appears exceeds the cyclic prefix section of the symbol section of the PSS (the section of the OFDM symbol and the cyclic prefix). Note that this shift amount can also be applied to the relationship between two second sequences.

[0018] Note that such a shift amount is specified based on, for example, the length of a cyclic prefix added to an OFDM symbol. In one example, as described above, three shift amount patterns 9×N (N=1, 2, 3) for generating a second sequence for one first sequence may be specified. Note that, when a plurality of second sequences are associated with one first sequence, the plurality of second sequences may be associated with different relay devices. In this way, the terminal device 111 can specify which of the second sequences the received PSS corresponds to, thereby specifying which relay device has relayed the PSS. For example, when the delay time associated with the relay process differs for each relay device, the reception timing may be corrected by a different amount of time depending on which relay device the PSS was relayed from. This can further improve the accuracy of location estimation by taking into account the difference in characteristics of the relay devices.

[0019] An overview of the operation when such processing is performed is shown in Fig. 2. It is assumed here that base station device 101, base station device 102, and base station device 103 transmit PSSs using sequences obtained by performing cyclic shifts of 43, 86, and 0 on the Zadoff-chu sequence, respectively. Then, first relay device 121 relays a PSS corresponding to a sequence obtained by performing a further cyclic shift of 18 on the received PSS, and second relay device 122 relays a PSS corresponding to a sequence obtained by performing a further cyclic shift of 9 on the received PSS. In other words, when first relay device 121 receives a PSS using a sequence obtained by performing a cyclic shift of 43, it can output a PSS corresponding to a sequence obtained by performing a cyclic shift of 43+18=61 on the original Zadoff-chu sequence. Furthermore, when the second relay device 122 receives a PSS using a sequence subjected to a cyclic shift of 43, it can output a PSS corresponding to a sequence obtained by subjecting the original Zadoff-chu sequence to a cyclic shift of 43+9=52. In FIG. 2, both the first relay device 121 and the second relay device 122 are configured to relay a signal from the base station device 103. Therefore, since the base station device 103 transmits a PSS using a sequence subjected to a cyclic shift of 0, the first relay device 121 and the second relay device 122 relay PSSs corresponding to sequences subjected to cyclic shifts of 18 and 9, respectively.

[0020] The shift amount in each relay device may be preset, for example, by receiving setting information from the base station device to be relayed or by manual setting by the communication carrier. In either case, information on the shift amount is shared between the base station device and the relay device. The base station device may hold information on the time used to correct the reception timing, such as the time required for relay processing in each relay device. The base station device may then report information indicating the time related to relay processing and the shift amount of the sequence for each relay device that relays the communication of the base station device, for example, by system information (for example, SIB1). Information that can identify the relay device does not need to be notified. That is, it is sufficient that the terminal device 111 can recognize the relationship between the shift amount and the correction amount of the reception timing of the PSS. By acquiring this information, the terminal device 111 can correct the reception timing by the amount of time corresponding to the relay processing in the relay device depending on which relay device relayed the PSS sent from the base station device, thereby improving the accuracy of location estimation.

[0021] In FIG. 2, the terminal device 111 detects a PSS generated using a sequence in which a Zadoff-chu sequence has been cyclically shifted by a shift amount of 43, transmitted from the base station device 101. The terminal device 111 also detects a PSS generated using a sequence in which a Zadoff-chu sequence has been cyclically shifted by a shift amount of 86, transmitted from the base station device 102. These shift amounts are the shift amounts when directly transmitted from the base station device, so the terminal device 111 can determine that these PSSs have been received without going through a relay device. The terminal device 111 can specify whether the PSS has been transmitted from the base station device 101 or the base station device 102, depending on whether the shift amount is 43 or 86. That is, the terminal device 111 can specify whether the detected PSS has been transmitted from the base station device 101 or the base station device 102.

[0022] On the other hand, the terminal device 111 cannot detect a PSS generated using a Zadoff-chu sequence that has not been cyclically shifted (shift amount is 0) and that has been transmitted from the base station device 103. At this time, the first relay device 121 relays a PSS corresponding to a sequence in which a cyclic shift of 18 has been applied to a Zadoff-chu sequence as described above. Also, the second relay device 122 relays a PSS corresponding to a sequence in which a cyclic shift of 9 has been applied to a Zadoff-chu sequence. This allows the terminal device 111 to detect PSSs corresponding to Zadoff-chu sequences with shift amounts of 9 and 18. Since the shift amount is not 0, 43, or 86, the terminal device 111 can determine that these PSSs have been received via a relay device. Also, when the shift amounts are 9 and 18, the terminal device 111 can determine that a PSS corresponding to a Zadoff-chu sequence with a shift amount of 0 has been relayed by a relay device. Therefore, the terminal device 111 can specify that the PSS from the base station device 103 has arrived after being relayed by a relay device. In this case, the terminal device 111 corrects the reception timing of the PSS so that the PSS from the base station device 103 appears to have arrived directly at a timing earlier than the timing at which the PSS was actually received by the timing corresponding to the time related to the relay process. The time related to the relay process may be notified from the base station device 103 (via the relay device 121 or the relay device 122). Also, for example, when the times related to the relay process differ between the first relay device 121 and the second relay device 122, the shift amount and information indicating the time may be associated with each other and notified to the terminal device 111. For example, information indicating the first time related to the relay process in the first relay device 121 and information associating the shift amount=18 in the first relay device 121 with each other is notified to the terminal device 111. Moreover, information indicating the second time related to the relay process in the second relay device 122 and information associating the shift amount=9 in the second relay device 122 are notified to the terminal device 111.As a result, the terminal device 111 can treat a timing that is a first time earlier than the timing at which a PSS corresponding to a Zadoff-chu sequence with a shift amount = 18 was received, or a timing that is a second time earlier than the timing at which a PSS corresponding to a Zadoff-chu sequence with a shift amount = 9 was received, as the timing at which a PSS was received from the base station device 103. Note that the terminal device 111 may treat the average timing of the timing that is a first time earlier than the timing at which a PSS corresponding to a Zadoff-chu sequence with a shift amount = 18 was received and the timing that is a second time earlier than the timing at which a PSS corresponding to a Zadoff-chu sequence with a shift amount = 9 was received, as the timing at which a PSS was received from the base station device 103.

[0023] As described above, the terminal device 111 can estimate its own location based on the time difference of arrival (TDOA) using the timings at which the PSSs from the base station device 101 and the base station device 102 were received and the corrected timing at which the PSS from the base station device 103 is estimated to have been received. This location estimation based on TDOA is a conventional technique, and will not be described here.

[0024] The above-mentioned PSS is an example of a predetermined signal, and another signal may be used. For example, a signal newly defined for position measurement may be used. The first sequence and the second sequence may not be sequences generated by applying a cyclic shift to a predetermined sequence. That is, it is sufficient that a predetermined signal is generated by a sequence selected from predetermined candidates so as to be detectable in a terminal device, the first sequence and the second sequence are mutually different, and one corresponding first sequence can be identified from the second sequence.

[0025] In order to execute the above-mentioned process, the relay device 121 has a function of at least identifying a predetermined signal, modifying and amplifying the predetermined signal, and outputting the modified signal. For example, the relay device 121 may execute a demodulation process on the received predetermined signal to identify a first sequence, and further perform a cyclic shift on the first sequence to generate a second sequence, and may regenerate and relay the predetermined signal based on the second sequence. In addition, when the relay device 121 identifies the first sequence used when the received predetermined signal is generated, the relay device 121 may transmit a predetermined signal prepared separately using a second sequence corresponding to the first sequence, instead of the received reference signal. In addition, the relay device 121 may be configured to output a predetermined signal based on a modified or separately prepared second sequence after a predetermined time has elapsed since the reception timing of the predetermined signal.

[0026] Furthermore, the relay device 121 can amplify and relay signals other than the predetermined signal as a wireless repeater without performing demodulation processing on the signal. That is, the relay device 121 has a function for performing the above-mentioned processing on the predetermined signal, and can function as a wireless repeater that performs non-regenerative relay on other signals.

[0027] (Device configuration) FIG. 3 is a diagram showing an example of a hardware configuration of the relay device 121. In one example, the relay device 121 includes a processor 301, a ROM 302, a RAM 303, a storage device 304, and a communication circuit 305. The processor 301 is a computer including one or more processing circuits such as a general-purpose CPU (Central Processing Unit) or an ASIC (Application Specific Integrated Circuit), and executes the overall processing of the device and each of the above-mentioned processes by reading and executing a program stored in the ROM 302 or the storage device 304. The ROM 302 is a read-only memory that stores information such as a program related to the processing executed by the relay device 121 and various parameters. The RAM 303 functions as a workspace when the processor 301 executes a program, and is a random access memory that stores temporary information. The storage device 304 is, for example, a removable external storage device. The communication circuit 305 is, for example, a circuit for wireless communication of LTE or 5G. 2, one communication circuit 305 is illustrated, but the relay device 121 may have multiple communication circuits. For example, the relay device 121 may have wireless communication circuits and antennas for LTE and 5G.

[0028] The terminal device 111 may also have a hardware configuration similar to that shown in FIG.

[0029] 4 is a diagram showing an example of the functional configuration of the relay device 121. The relay device 121 includes, for example, a relay processing unit 401, a PSS detection unit 402, and a PSS transformation unit 403. These functional units may be implemented, for example, by the processor 301 executing a program stored in the ROM 302 or the storage device 304. However, this is not limited to this, and for example, some or all of these functional units may be implemented using dedicated hardware. Note that since the processes to be executed by the relay device 121 have been described above, the functional configuration of the relay device 121 will be merely roughly outlined here.

[0030] Relay processing unit 401 amplifies signals received from base station device 103 and transmits them to terminal device 111, and also amplifies signals received from terminal device 111 and transmits them to base station device 103. Relay device 121 is, for example, a non-regenerative relay device (wireless repeater), and relay processing unit 401 is configured to amplify (and frequency convert as necessary) signals other than predetermined signals used for positioning such as PSS without demodulating and decoding them, and output them. Note that when relay device 121 is a regenerative relay device, relay processing unit 401 can be configured to demodulate and decode the received signal, encode and modulate the data sequence obtained thereby, and regenerate and output the radio signal.

[0031] The PSS detection unit 402 performs a PSS detection process in a frequency and time resource in which a PSS (a predetermined signal) can be transmitted. For example, the PSS detection unit 402 performs correlation detection using a first sequence that can be used when the base station device 103 generates a PSS in that frequency and time resource, and can determine that a PSS has arrived when a peak appears in the correlation value. When a PSS is detected by the PSS detection unit 402, the PSS modification unit 403 modifies the PSS into a format that allows the terminal device 111 to identify that the PSS has arrived via the relay device 121. For example, the PSS modification unit 403 can perform a cyclic shift by a predetermined shift amount on a first sequence corresponding to the received PSS, and output a PSS corresponding to a second sequence that is not used by the base station device 103 to transmit the PSS. Note that the PSS modification unit 403 may generate a new PSS, for example, by using a second sequence corresponding to the first sequence used in the PSS detection by the PSS detection unit 402 to detect the PSS. The transformed or newly generated PSS output by the PSS transformation unit 403 is sent via the relay processing unit 401 .

[0032] 5 is a diagram showing an example of the functional configuration of the terminal device 111. The terminal device 111 includes, for example, a PSS detection timing identification unit 501, a detection timing correction unit 502, and a position estimation unit 503. Note that these functional units can be implemented, for example, by the processor 301 executing a program stored in the ROM 302 or the storage device 304. However, this is not limited to this, and for example, some or all of these functional units may be implemented using dedicated hardware.

[0033] The PSS reception timing specification unit 501 detects the PSS that may be sent from each base station device and the PSS that may be transferred from each relay device, and specifies the detection timing. For example, the PSS reception timing specification unit 501 detects the PSS sent from each base station device using a Zadoff-chu sequence cyclically shifted by a shift amount that each base station device can use to generate a PSS, and specifies the detection timing. The PSS reception timing specification unit 501 also detects the PSS relayed by each relay device using a Zadoff-chu sequence whose shift amount has been changed by the relay device, and specifies the detection timing. When the PSS relayed by the relay device is detected, the reception timing correction unit 502 corrects the detection timing so that the PSS arrives earlier than the actual detection timing by a time related to the relay processing by the relay device. Note that the time related to the relay processing in the relay device 121 may be, but is not limited to, the time required for the relay processing itself. For example, the time related to the relay process may include a time corresponding to an expected value of a path difference between the straight-line distance from the position of the terminal device 111 to the position of the base station device and the distance of the path from the terminal device 111 to the base station device when the PSS is received via the relay device 121. For example, the positions of at least some of the terminal devices whose communications are relayed by the relay device 121 are measured in advance using GNSS or the like, and the expected value of the path difference can be specified from the distribution of the results. In one example, when the PSS is received via relaying by the relay device 121, the timing can be corrected so that the PSS arrives at the base station device earlier than the actual reception timing by the expected value of the path difference.

[0034] The position estimation unit 503 performs positioning based on, for example, the time difference of arrival (TDOA). The position estimation unit 503 estimates the position of the terminal device 111 based on the difference in detection timing of the PSS from multiple (e.g., three) base station devices acquired by the PSS detection timing identification unit 501 or the detection timing correction unit 502. That is, the position estimation unit 503 performs position estimation based on TDOA using the timing at which the PSS was actually received when the PSS reached the terminal device 111 without being relayed by the relay device 121, and using the corrected timing when the PSS was received via relaying by the relay device 121.

[0035] (Processing flow) Next, an example of the flow of processing executed in the wireless communication system will be described with reference to FIG.

[0036] The base station device 101 generates a PSS using a sequence obtained by performing a cyclic shift of 43 on the Zadoff-chu sequence, for example, and transmits it to the surroundings. The base station device 102 generates a PSS using a sequence obtained by performing a cyclic shift of 86 on the Zadoff-chu sequence, for example, and transmits it to the surroundings (S601). It is assumed that the terminal device 111 can directly receive this PSS. The terminal device 111 detects the PSS from the base station device 101 by performing correlation detection using the sequence used by the base station device 101 to generate the PSS, and detects the PSS from the base station device 102 by performing correlation detection using the sequence used by the base station device 102 to generate the PSS. It is assumed that the terminal device 111 can detect the PSS by correlation detection using the sequence obtained by performing cyclic shifts of 43 and 86 on the Zadoff-chu sequence in this case. In this case, terminal device 111 determines that the PSS from base station device 101 and base station device 102 arrived without passing through a relay device (S602), and holds the timing at which the PSS was detected as is (S603). Note that terminal device 111 performs correlation detection using a sequence with a changed shift amount when a relay device is used, but if there is no relay device in the vicinity that relays signals from base station device 101 and base station device 102, it will not detect a PSS corresponding to that sequence.

[0037] Meanwhile, like base station device 101 and base station device 102, base station device 103 generates a PSS using a sequence obtained without performing a cyclic shift on the Zadoff-chu sequence (a shift amount of 0) and transmits it to the surroundings (S604). On the other hand, terminal device 111 is located in a position where it cannot directly receive a signal from base station device 103, and cannot detect the PSS even if it performs correlation detection using the sequence used by base station device 103 to generate the PSS. On the other hand, terminal device 111 can detect the PSS transmitted from base station device 103 and relayed by relay device 121 by performing correlation detection using a sequence with a changed shift amount when a relay device is used (S605). That is, terminal device 111 can detect the PSS by correlation detection using a sequence obtained by performing a cyclic shift with a shift amount of 18 on the Zadoff-chu sequence. In this case, the terminal device 111 determines that the PSS from the base station device 103 has arrived via the relay device 121 (S606), and corrects the timing at which the PSS was detected (S607). The terminal device 111 then performs location estimation based on TDOA (S608) using the detection timing of the PSS from the base station device 101 and the base station device 102 obtained in S603 and the detection timing of the PSS from the base station device 103 after the correction obtained in S607. Note that, in the above example, for the sake of simplicity, an example has been shown in which the detection of the PSS from the base station device 101 and the base station device 102 and the detection of the PSS from the base station device 103 are performed at different timings, but these processes may be performed in parallel.

[0038] As described above, in this embodiment, the reception timing of the PSS from each base station device is identified by removing the effect of delay caused by the relay process by the relay device 121, so it is possible to improve the estimation accuracy of the location of the terminal device 111. This makes it possible to contribute to Goal 9 of the Sustainable Development Goals (SDGs) led by the United Nations, which is to "build resilient infrastructure, promote sustainable industrialization and foster innovation."

[0039] The invention is not limited to the above-described embodiment, and various modifications and variations are possible within the scope of the gist of the invention.

Claims

1. A relay device, A relay unit that relays a radio signal received from a base station device to a terminal device; a control means for controlling the relay means, when a predetermined signal generated using a first sequence is received from the base station device, to relay to the terminal device a predetermined signal corresponding to a second sequence that corresponds to the first sequence, the second sequence being not used when the base station device generates the predetermined signal; having The relay device is characterized in that, when a signal different from the specified signal is received from the base station device, the relay means amplifies the signal without performing demodulation processing on the signal and transfers it to the terminal device.

2. 2. The relay device according to claim 1, wherein the first sequence is a sequence obtained by performing a cyclic shift on a predetermined sequence by a first shift amount or the predetermined sequence itself, and the second sequence is a sequence obtained by performing a cyclic shift on the predetermined sequence by a second shift amount that is not used as the first shift amount.

3. 3. The relay device according to claim 2, wherein the second shift amount is a shift amount obtained by adding a predetermined shift amount to a value that can be used as the first shift amount.

4. 4. The relay device according to claim 3, wherein the predetermined shift amount is set based on a length of a cyclic prefix added to an orthogonal frequency division multiplexing (OFDM) symbol.

5. 5. The relay device according to claim 1, wherein the predetermined signal is a Primary Synchronization Signal (PSS).

6. A terminal device, A detection means for detecting an incoming predetermined signal; an estimation means for estimating a location of the terminal device based on the detected predetermined signal and a location of a base station device that is a source of the predetermined signal; The estimation means includes: when detecting the predetermined signal generated using a first sequence, estimating a position of the terminal device using a timing at which the predetermined signal was detected; when detecting a predetermined signal corresponding to a signal generated using a second sequence related to the first sequence and not used when the base station device generates the predetermined signal, correcting the timing by a time related to a relay process in a relay device so that the predetermined signal appears to have arrived earlier than the timing at which the predetermined signal was detected, thereby estimating a position of the terminal device. A terminal device comprising:

7. 7. The terminal device according to claim 6, further comprising an acquisition unit for acquiring information indicating a time related to the relay process from the base station device.

8. The terminal device according to claim 7 , wherein the acquisition means acquires information indicating a time related to the relay process from system information notified by the base station device.

9. 9. The terminal device according to claim 7, wherein, when a plurality of relay devices are present, the acquisition means acquires information indicating a time related to the relay process for each of the plurality of relay devices.

10. a different second sequence corresponds to each of the plurality of relay devices; when detecting the predetermined signal corresponding to the signal generated using the second sequence, the estimation means corrects the timing by a time period related to the relay process associated with the relay device corresponding to the second sequence among the plurality of relay devices.

10. The terminal device according to claim 9 .

11. A control method executed by a relay device having a relay unit that relays a radio signal received from a base station device to a terminal device, comprising: controlling the relay means to relay, when a predetermined signal generated using a first sequence is received from the base station device, to the terminal device, the predetermined signal corresponding to a second sequence that corresponds to the first sequence, the second sequence being not used when the base station device generates the predetermined signal; A control method characterized in that, when a signal different from the specified signal is received from the base station device, the relay device amplifies the signal without performing demodulation processing on the signal and forwards it to the terminal device.

12. A control method executed by a terminal device, comprising: Detecting an incoming predetermined signal; estimating a location of the terminal device based on the detected predetermined signal and a location of a base station device that is a source of the predetermined signal; Including, In estimating the position of the terminal device, a position of the terminal device is estimated using a timing at which the predetermined signal generated using a first sequence is detected; and when detecting a predetermined signal corresponding to a signal generated using a second sequence related to the first sequence and not used when the base station device generates the predetermined signal, the timing is corrected by a time related to a relay process in a relay device so that the predetermined signal appears to have arrived earlier than the timing at which the predetermined signal was detected, thereby estimating the position of the terminal device. A control method comprising:

13. A program for causing a computer to function as the relay device according to any one of claims 1 to 5.

14. A program for causing a computer to function as the terminal device according to any one of claims 6 to 10.

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