Communication device, communication method, and communication system

Abstract

Improving reliability of a D2D communication system generating aperiodic traffic. A communication device supports D2D (device-to-device) communication, and includes a listening interval decision section, a listening section, and a resource decision section. The listening interval decision section decides a listening interval in which listening is performed, based on a selection candidate time slot set including time slots set for transmitting a D2D signal. The listening section performs listening in the listening interval decided by the listening interval decision section. The resource decision section decides a resource for transmitting a D2D signal from the selection candidate time slot set based on a result of the listening by the listening section.

Description

Technical Field

[0001] This invention relates to communication devices, communication methods, and communication systems. Background Technology

[0002] Currently, most network resources are consumed by services used by mobile devices (including smartphones or feature phones). Furthermore, it is believed that the number of services used by mobile devices will continue to increase in the future.

[0003] On the other hand, with the development of IoT (Internet of Things) services (such as transportation systems, smart meters, and monitoring systems for devices), there is a need to address services with various requirements. Therefore, in the standards for fifth-generation mobile communication (5G or NR (New Radio)), in addition to the standard technologies of fourth-generation mobile communication (4G (LTE: Long Term Evolution)) (e.g., Non-Patent Documents 1-12), there is a requirement to achieve higher data rates, larger capacity, and lower latency. Furthermore, the standards for fifth-generation mobile communication have been studied in the working groups of 3GPP (Third Generation Partnership Project) (e.g., TSG-RAN WG1, TSG-RAN WG2, etc.), and a preliminary version of the standard specification was published at the end of 2017 (e.g., Non-Patent Documents 13-39).

[0004] Furthermore, V2X (Vehicle to Everything) communication was discussed in 3GPP working group meetings. V2X includes V2V (Vehicle to Vehicle) for communication between vehicles, V2P (Vehicle to Pedestrian) for communication between vehicles and pedestrians, V2I (Vehicle to Infrastructure) for communication between vehicles and road infrastructure, and V2N (Vehicle to Network) for communication between vehicles and networks. Specifications regarding V2X are described, for example, in Non-Patent Document 1. Additionally, communication devices that enable more flexible resource allocation in device-to-device communication, represented by V2X, have been proposed (e.g., Patent Document 1).

[0005] In V2X communication, for example, an autonomous resource allocation method (Mode 2) is used. In this method, the communication device listens before sending a signal to determine the resources to be used. For example, the communication device detects resources reserved by other communication devices by listening for a specified period. However, this method increases the power consumption of the communication device. Therefore, in the case of periodic data transmission in V2X communication, a method has been proposed to listen only at a specified time corresponding to that period. Furthermore, in the following description, the method of listening only at a specified time is sometimes referred to as "partial listening".

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: WO2019 / 187562

[0009] Non-patent literature

[0010] Non-patent literature 1: 3GPP TS 22.186V 16.2.0 (2019-06)

[0011] Non-patent document 2: 3GPP TS 36.211 V16.0.0 (2019-12)

[0012] Non-patent document 3: 3GPP TS 36.212 V16.0.0 (2019-12)

[0013] Non-patent document 4: 3GPP TS 36.213 V16.0.0 (2019-12)

[0014] Non-patent document 5: 3GPP TS 36.300 V16.0.0 (2019-12)

[0015] Non-patent document 6: 3GPP TS36.321 V15.8.0 (2019-12)

[0016] Non-patent document 7: 3GPP TS 36.322V 15.3.0 (2019-09)

[0017] Non-patent document 8: 3GPP TS 36.323V 15.5.0 (2019-12)

[0018] Non-patent document 9: 3GPP TS 36.331 V15.8.0 (2019-12)

[0019] Non-patent document 10: 3GPP TS36.413 V16.0.0 (2019-12)

[0020] Non-patent document 11: 3GPP TS 36.423 V16.0.0 (2019-12)

[0021] Non-patent document 12: 3GPP TS 36.425 V15.0.0 (2018-06)

[0022] Non-patent document 13: 3GPP TS 37.340 V16.0.0 (2019-12)

[0023] Non-patent document 14: 3GPP TS 38.201 V16.0.0 (2019-12)

[0024] Non-patent document 15: 3GPP TS 38.202 V16.0.0 (2019-12)

[0025] Non-patent document 16: 3GPP TS 38.211 V16.0.0 (2019-12)

[0026] Non-patent document 17: 3GPP TS 38.212 V16.0.0 (2019-12)

[0027] Non-patent document 18: 3GPP TS 38.213 V16.0.0 (2019-12)

[0028] Non-patent document 19: 3GPP TS 38.214 V16.0.0 (2019-12)

[0029] Non-patent document 20: 3GPP TS 38.215 V16.0.1 (2020-01)

[0030] Non-patent document 21: 3GPP TS 38.300 V16.0.0 (2019-12)

[0031] Non-patent document 22: 3GPP TS 38.321 V15.8.0 (2019-12)

[0032] Non-patent document 23: 3GPP TS 38.322 V15.5.0 (2019-03)

[0033] Non-patent document 24: 3GPP TS 38.323 V15.6.0 (2019-06)

[0034] Non-patent document 25: 3GPP TS 38.331 V15.8.0 (2019-12)

[0035] Non-patent document 26: 3GPP TS 38.401 V16.0.0 (2019-12)

[0036] Non-patent document 27: 3GPP TS 38.410 V16.0.0 (2019-12)

[0037] Non-patent document 28: 3GPP TS 38.413 V16.0.0 (2019-12)

[0038] Non-patent document 29: 3GPP TS 38.420 V15.2.0 (2018-12)

[0039] Non-patent document 30: 3GPP TS 38.423 V16.0.0 (2019-12)

[0040] Non-patent document 31: 3GPP TS 38.470 V16.0.0 (2019-12)

[0041] Non-patent document 32: 3GPP TS 38.473 V16.0.0 (2019-12)

[0042] Non-patent document 33: 3GPP TR38.801 V14.0.0 (2017-03)

[0043] Non-patent document 34: 3GPP TR38.802 V14.2.0 (2017-09)

[0044] Non-patent document 35: 3GPP TR38.803 V14.2.0 (2017-09)

[0045] Non-patent document 36: 3GPP TR38.804 V14.0.0 (2017-03)

[0046] Non-patent document 37: 3GPP TR 38.900 V15.0.0 (2018-06)

[0047] Non-patent document 38: 3GPP TR38.912 V15.0.0 (2018-06)

[0048] Non-patent document 39: 3GPP TR38.913 V15.0.0 (2018-06) Summary of the Invention

[0049] The problem that the invention aims to solve

[0050] As described above, in order to reduce the power consumption of communication devices in V2X, partial listening is proposed, which involves listening only at intervals corresponding to a predetermined period. Furthermore, the communication device can determine the available resources based on partial listening and use those resources to transmit signals.

[0051] However, it is believed that aperiodic traffic increases in NR-V2X, which supports new communication services. Furthermore, in previous partial eavesdropping, it is difficult to detect resources reserved through aperiodic traffic. That is, in wireless communication systems that generate aperiodic traffic, packet collisions may occur in previous partial eavesdropping, reducing the reliability of V2X communication. Moreover, this problem not only occurs in V2X communication but may also occur in any D2D (Device-to-Device) communication.

[0052] One objective of this invention is to improve the reliability of D2D communication systems that generate non-periodic services.

[0053] Methods for solving problems

[0054] One aspect of the present invention relates to a communication device that supports D2D (Device-to-Device) communication. The communication device comprises: a listening interval determination unit that determines a listening interval for listening based on a selected candidate time slot set, the selected candidate time slot set including time slots configured to transmit D2D signals; a listening unit that listens within the listening interval determined by the listening interval determination unit; and a resource determination unit that determines resources for transmitting D2D signals from the selected candidate time slot set based on the listening results of the listening unit.

[0055] Invention Effects

[0056] Based on the above methods, the reliability of D2D communication systems that generate non-periodic services can be improved. Attached Figure Description

[0057] Figure 1 This is a diagram illustrating an example of a wireless communication system according to an embodiment of the present invention.

[0058] Figure 2 This is a diagram illustrating an example of a method for determining resources based on listening.

[0059] Figure 3 This is another example of a method for determining resources based on listening.

[0060] Figure 4 This is a diagram illustrating an example of resource reservation for NR-V2X.

[0061] Figure 5This is a diagram illustrating an example of a listening method according to an embodiment of the present invention.

[0062] Figure 6 This is a diagram illustrating an example of a method for detecting reserved resources.

[0063] Figure 7 This is a diagram illustrating an example of a candidate time slot composed of discontinuous time slots.

[0064] Figure 8 This diagram illustrates an example of partial listening to the appointment process for a testing cycle service.

[0065] Figure 9 This is a diagram representing an example of a listening range.

[0066] Figure 10 This is a graph showing the comparison results regarding the reduction in power consumption.

[0067] Figure 11 This is a flowchart illustrating an example of a communication method according to an embodiment of the present invention.

[0068] Figure 12 This is a diagram illustrating an example of the structure of a base station.

[0069] Figure 13 This is a diagram illustrating an example of the structure of a communication device.

[0070] Figure 14 This is a diagram illustrating an example of resource reselection.

[0071] Figure 15 This is a diagram illustrating an example of a prediction triggered by resource (re)selection. Detailed Implementation

[0072] The topics and embodiments described in this specification are illustrative and are not intended to limit the scope of this application. For example, even if the descriptions differ, the technology of this application can be applied as long as they are technically equivalent. Furthermore, the embodiments described in this specification can be combined without contradiction.

[0073] The terms and technical content used in this specification may also be used as those described in specifications (e.g., 3GPP TS38.211 V16.0.0 (2019-12)) or in submissions as part of communication-related standards such as 3GPP.

[0074] Figure 1 An example of a wireless communication system illustrating an embodiment of the present invention. For example... Figure 1 As shown, the wireless communication system 100 includes a base station 1 and multiple communication devices 2.

[0075] Base station 1 controls the cellular communication of communication device 2 (uplink / downlink communication via the Uu interface). That is, base station 1 receives uplink signals (control signals and data signals) from communication device 2. In addition, base station 1 sends downlink signals (control signals and data signals) to communication device 2.

[0076] Communication device 2 can communicate with other communication devices via base station 1. Additionally, communication device 2 can also communicate with other communication devices without using base station 1. That is, communication device 2 supports D2D (Device-to-Device) communication. D2D communication, for example, transmits signals via the PC5 interface. Furthermore, D2D communication is sometimes referred to as "sidelink communication." Moreover, communication device 2 is sometimes referred to as "UE (User Equipment)."

[0077] When communication device 2 transmits data via D2D communication, it determines the resources to be used for transmitting the data. At this time, communication device 2 checks for resources reserved by other communication devices in the resources pre-set for D2D communication (i.e., the resource pool). Then, communication device 2 uses resources not reserved by other communication devices to transmit the data. In the following description, the process of detecting resources reserved by other communication devices in the resource pool used for D2D communication is sometimes referred to as "listening".

[0078] Figure 2 This illustrates an example of a method for determining resources based on listening. Here, it is assumed that a resource (re)selection trigger is generated in subframe n. The resource (re)selection trigger is, for example, equivalent to an indication to determine resources in order to transmit data generated by an application installed in communication device 2. Furthermore, it is assumed that the timing of generating the resource (re)selection trigger is predictable. That is, communication device 2 is able to predict the timing of generating the resource (re)selection trigger.

[0079] Communication device 2 sets a selection window and a listening window for resource (re)selection triggers. The selection window represents the range of selectable resources. That is, communication device 2 can select resources for data transmission from the resources within the selection window. When a resource (re)selection trigger is generated in subframe n, the range of the selection window is subframe "n+T1, n+T2". Parameters T1 and T2 are, for example, preset. Alternatively, parameters T1 and T2 are notified from base station 1.

[0080] The listening window represents the range within which the communication device 2 listens. That is, the communication device 2 listens for each resource within the listening window. Here, the communication device 2 listens for, for example, the 1000 subframes immediately preceding the resource (re)selection trigger. In this case, when the prediction is to generate a resource (re)selection trigger in subframe n, the range of the listening window is subframes "n-1000, n-1".

[0081] In the listening process, communication device 2 decodes the transmitted control channel (PSCCH, Physical Sidelink Control Channel) within the listening window and measures the received power of the corresponding data channel (PSSCH, Physical Sidelink Shared Channel). The resource mapping for the PSCCH includes, for example, sidelink control information (SCI) containing resources of the corresponding data channel (PSSCH) and information related to the reservation of transmission resources. Received power measurement includes, for example, measuring the received power of the reference signal (RSRP) and / or RSSI (Received Signal Strength Indicator).

[0082] In NR-V2X, the control channel (PSCCH: Physical Sidelink Control Channel) and data channel (PSSCH: Physical Sidelink Shared Channel) are multiplexed using TDM (Time Division Multiplexing) or FDM (Frequency Division Multiplexing). Furthermore, to improve the channel quality of the sidelink, a feedback channel (PSFCH: Physical Sidelink Feedback Channel) is introduced.

[0083] exist Figure 2 In the example shown, some resources within the selection window are reserved by other communication devices (UE1 and UE2). In this case, communication device 2 excludes the reserved resources with a receive power higher than a predetermined threshold from the resources within the selection window, and determines the resources to be used for data transmission from the remaining resources. Additionally, Figure 2 The eavesdropping record shown is in 3GPP Release 14.

[0084] However, in Figure 2In the method shown, the power consumption of the communication device 2 increases due to continuous listening over a long period. On the other hand, in most cases, the battery capacity of communication devices carried by pedestrians is small. Therefore, a listening method with low power consumption is required.

[0085] Figure 3 Another example of a method for determining resources based on listening is shown. Here, D2D communication sends packets at a predetermined period. Specifically, D2D communication sends packets at k×100m second intervals. k is not particularly limited and in this example is 1, 2, 5, or 10.

[0086] In this case, communication device 2 also... Figure 2 Similarly, in the illustrated scenario, a selection window and a listening window are set corresponding to the resource (re)selection trigger. However, communication device 2 sets a selection candidate subframe set within the selection window. In this example, the selection candidate subframe set consists of Y consecutive subframes. Figure 3 In this case, Y=5, and the candidate subframe set consists of 5 consecutive subframes. Additionally, Figure 3 The "candidate" option indicates the selection of a candidate subframe set.

[0087] Here, when resources within the candidate subframe set are used by periodic services of other communication devices, the last transmission should have occurred k×100m seconds prior to the candidate subframe set. Therefore, if resources prior to the candidate subframe set (k×100m seconds ago) are monitored, when a resource (re)selection trigger is generated, communication device 2 can determine whether resources within the candidate subframe set have been reserved by periodic services of other communication devices.

[0088] Therefore, communication device 2 sets a listening interval within the listening window that corresponds to the selected candidate subframe set. Specifically, as follows: Figure 3 As shown, based on the selection of candidate subframe sets, a listening interval is set k×100m seconds in advance. The length of each listening interval is the same as the length of the selected candidate subframe set. That is, each listening interval consists of Y subframes.

[0089] When a resource (re)selection trigger is generated in subframe m, communication device 2 in Figure 3 Listening is conducted in the four listening intervals shown. In this case, communication device 2 detects the availability of specified resources within the periodic service reservation candidate subframe set of UE1 and UE2 by receiving control signals (e.g., SCI) transmitted from UE1 and UE2 respectively. Furthermore, the received power of the PSSCH corresponding to the control signal is measured. Then, communication device 2 excludes resources reserved by UE1 / UE2 with received power higher than a predetermined threshold from the resources within the selection candidate subframe set, and determines the resources for data transmission from the remaining resources. Additionally, Figure 3The eavesdropping described is also documented in 3GPP Release 14.

[0090] Thus, according to Figure 3 The method shown is the same as Figure 2 Compared to the method shown, the eavesdropping period is shorter, thus reducing the power consumption of communication device 2. However, it is believed that non-periodic traffic increases in NR-V2X supporting new communication services. Furthermore, in Figure 3 In the method shown, communication device 2 cannot detect resources reserved by aperiodic services within the selected candidate subframe set. That is, in a wireless communication system that generates aperiodic services, packets transmitted by communication device 2 may conflict with packets from aperiodic services of other communication devices, potentially reducing the reliability of V2X communication.

[0091] Thus, in D2D communication systems, there is a demand for both reduced power consumption of the communication device and improved communication reliability. Specifically, this requires... Figure 2 The method shown reduces power consumption and is comparable to Figure 3 The method shown is compared to methods for improving communication reliability.

[0092] <Implementation Method>

[0093] As mentioned above, in Figure 3 In the method shown, the reliability of communication may decrease when non-periodic services occur. Therefore, firstly, the reservation of resources related to non-periodic services in D2D communication is simply recorded.

[0094] Figure 4 This illustrates an example of resource reservation for NR-V2X. NR-V2X supports retransmission processing. That is, when a communication device uses a resource to transmit data, it can reserve that resource for retransmitting that data. For example, as... Figure 4 As shown, assume data is transmitted in time slot n. In this case, the scheduling window is set based on time slot n. In this example, the scheduling window consists of 32 time slots. Furthermore, the communication device can reserve resources for retransmission within the scheduling window. The number of resources that can be reserved, including the initial transmission, is 2 or 3. Additionally, the scheduling window is an example of the range of resources that can be reserved for retransmission corresponding to the initial transmission of D2D data.

[0095] exist Figure 4 In the example shown, resources for retransmission are reserved in time slots n+10 and n+26. Furthermore, the size of the resources reserved for retransmission is the same as the initial transmission. However, resources for retransmission can be reserved for the desired time and frequency within the scheduling window.

[0096] Information related to the reservation of resources used for resending is included, for example, in the SCI. Figure 4 In this context, "C" represents the SCI. In this case, information related to the reservation of resources used for retransmission is included in the SCI set within the control channel of the initial transmission. For example, during the initial transmission in time slot n, resources (n+10, n+26) for retransmission are reserved using the SCI set for the control channel of time slot n. However, it is also possible to reserve retransmission resources (n+10) using the SCI set for time slot n, and reserve retransmission resources (n+26) using the SCI set for time slot n+10.

[0097] When using the aforementioned scheduling window to reserve retransmission resources, the maximum interval between the initial transmission and the retransmission is 32 time slots (i.e., the width of the scheduling window). In other words, when reserving a resource X for retransmission, the initial transmission corresponding to that retransmission should occur within 32 time slots prior to resource X. Therefore, when reserving for retransmission... Figure 3 When selecting resources within the candidate subframe set, the initial transmission should have occurred within a range of 32 time slots prior to the selection of that candidate subframe set. Therefore, the communication device 2 of this embodiment of the invention considers such resource reservations for retransmission to determine the listening interval.

[0098] Figure 5 An example of the eavesdropping method according to an embodiment of the present invention is shown. Furthermore, in this embodiment, communication is performed in units of time slots. When the subframe length is Ls, the time slot length is selected, for example, from Ls, Ls / 2, Ls / 4, and Ls / 8.

[0099] Communication device 2 and Figure 2 or Figure 3 Similarly, the setup and listening window correspond to the resource (re)selection trigger. Additionally, communication device 2 and... Figure 3 Similarly, as shown, the selection window sets the candidate time slot set.

[0100] When resource (re)selection triggers are generated in time slot m, the selection window is set to the range of time slots "m+T1, m+T2". Parameters T1 and T2 are, for example, preset. Alternatively, parameters T1 and T2 are notified from base station 1. In this embodiment, the candidate time slot set is composed of Y consecutive subframes within the selection window. Here, the candidate time slot set can be set at a desired position within the selection window. Furthermore, in Figure 5 In the example shown, Y=5, and the candidate time slot set consists of 5 consecutive time slots.

[0101] When a resource (re)selection trigger is generated in time slot m, the range of the listening window is set to time slot "m-T0, m-Tp". T0 is not particularly limited and can be arbitrarily determined within the range of 100m seconds to 1100m seconds. Tp represents the time required for listening-related processing in communication device 2. The time required for listening-related processing includes, for example, processing for calculating received power and processing for decoding the received signal to obtain SCI. Here, when the time required for listening-related processing is sufficiently short relative to the processing capacity of communication device 2, the range of the listening window can also be set to time slot "m-T0, m-1". Furthermore, parameters T0 and Tp are, for example, preset. Alternatively, parameters T0 and Tp are notified from base station 1.

[0102] Communication device 2 sets a listening interval A within the listening window. Listening interval A is determined based on the set of candidate time slots set within the selection window. Specifically, the starting position of listening interval A is determined based on the position of the earliest time slot in the candidate time slot set.

[0103] Here, we assume that the first slot selected from the candidate slot set is ty0. In this case, as... Figure 5 As shown, the starting time slot of listening interval A is "ty0-W". That is, the starting position of listening interval A corresponds to the time slot after the width W of the scheduling window, based on the earliest time slot in the candidate time slot set. Conversely, the ending time slot of listening interval A is "m-Tp". That is, the ending position of listening interval A corresponds to the time slot after the time required for listening-related processing, based on the time slot that triggered the resource (re)selection. In this example, the ending time slot of listening interval A coincides with the last time slot of the listening window.

[0104] Communication device 2 listens within the aforementioned listening interval A. Furthermore, based on the listening results, communication device 2 selects resources (i.e., time slots) from a set of candidate time slots for transmitting D2D signals. Then, communication device 2 uses the selected resources to transmit data.

[0105] exist Figure 6 In the illustrated embodiment, a resource (re)selection trigger is predicted to be generated in time slot m. Furthermore, communication device 2 sets the candidate time slot set to time slot "ty0, ty0+4". In this case, communication device 2 sets a listening interval A in time slot "ty0-W, m-Tp". Additionally, it is assumed that communication device 2 predicts that a resource (re)selection trigger will be generated in time slot m before time slot ty0-W. Then, when communication device 2 predicts that a resource (re)selection trigger will be generated in time slot m, it listens in time slot "ty0-W, m-Tp".

[0106] In this embodiment, UE1 transmits a D2D signal in time slots ty0-W. Furthermore, communication device 2 acquires the SCI transmitted by UE1 in time slots ty0-W by listening to each resource in listening interval A. It is assumed that the acquired SCI contains information related to resource reservations for retransmission. Here, it is assumed that the SCI means "reserving resources for retransmission in time slot ty0". Additionally, communication device 2 measures the RSRP of the PSCCH or the corresponding PSSCH transmitted from UE1. When the measured value is higher than a predetermined threshold, communication device 2 excludes the resources reserved by UE1 from the resource selection candidate time slot set. Then, communication device 2 determines the resources for transmitting data from the remaining resources in the selection candidate time slot set.

[0107] Here, as referenced Figure 4 As explained, resources for retransmission are reserved within the scheduling window. Furthermore, the starting time slot of the listening interval A is located at a position W wide of the scheduling window preceding the earliest time slot in the candidate time slot set. Therefore, when resources in the candidate time slot set are reserved for retransmission of D2D communication, the probability of performing the initial transmission corresponding to that retransmission within the listening interval A is high. That is, when resources for retransmission are reserved within the candidate time slot set, the probability of detecting the initial transmission corresponding to that retransmission by listening within the listening interval A is high. Moreover, if communication device 2 obtains the SCI of the initial transmission, it can determine the resources reserved for retransmission within the candidate time slot set. Therefore, communication device 2 can determine the resources for transmitting D2D signals in a manner that does not conflict with packets transmitted from other communication devices.

[0108] In addition, Figure 6 In the example shown, resources for retransmission are reserved in the earliest slot within the candidate slot set. However, even if resources are reserved in other slots within the candidate slot set, the probability of the corresponding initial transmission occurring within listening interval A is high. For example, when resources for retransmission are reserved in the fifth slot (i.e., ty0+4) of the candidate slot set, the corresponding initial transmission, even in the earliest case, is in slot "ty0+4-W". Therefore, if communication device 2 listens within listening interval A, it can determine the reserved resources in the candidate slot set.

[0109] Furthermore, the communication device 2 sets the listening interval A when the conditions expressed by the following formula are met.

[0110] Condition: ty0-W≤m-Tp

[0111] Furthermore, when this condition is met, a listening interval A is set, consisting of time slots “ty0-W”, “ty0-W+1”, ..., “m-Tp”.

[0112] Furthermore, to reduce power consumption, communication device 2 preferably operates in sleep mode during periods when not listening. In sleep mode, communication device 2 does not listen. That is, in sleep mode, communication device 2 does not perform decoding of received signals or measurement of received power. Moreover, when a listening interval A is set according to resource (re)selection trigger, communication device 2 switches its operating mode from sleep mode to listening mode immediately before listening interval A. That is, communication device 2 listens from time slot "ty0-W" to time slot "m-Tp".

[0113] Furthermore, in the above embodiments, the starting time slot of the listening interval A is determined by the width W of the scheduling window offset from the earliest time slot in the candidate time slot set, but the present invention is not limited to this feature. For example, the starting time slot of the listening interval A can also be determined by half the width of the scheduling window offset from the earliest time slot in the candidate time slot set (i.e., W / 2).

[0114] Furthermore, in the above embodiments, the candidate time slot set is composed of Y consecutive time slots, but the present invention is not limited to this feature. That is, the candidate time slot set can also be composed of multiple non-consecutive time slots. For example, in Figure 7 In the example shown, the candidate time slot set consists of four non-contiguous time slots. However, in this case, the starting time slot of the listening interval A is also determined by offsetting the width W of the scheduling window from the earliest time slot (i.e., ty0) of the candidate time slot set.

[0115] Figures 5-7 The method shown primarily detects resource reservations used for retransmission of non-periodic services. On the other hand, Figure 3 The methods shown primarily detect resource reservations for periodic services. Therefore, combining these methods allows for the detection of resource reservations for both periodic and non-periodic services.

[0116] In this case, resource reservations for cyclical services, for example, utilize Figure 8 The listening interval B shown is used for detection. The listening interval is set in... Figure 3 as well as Figure 8 They are essentially the same. However, in Figure 8 In the method shown, the listening interval B is set in units of time slots. When a resource (re)selection trigger is generated in time slot m, the range of the listening window is "m-T0, m-Tp". The period of the detected object is P1, P2, ..., Pn. In this case, the position of each listening interval B is determined by offsetting the candidate time slot set by P1, P2, ..., Pn.

[0117] For example, such as Figure 9As shown, communication device 2 sets a listening interval A for resource (re)selection triggers in order to detect resource reservations for retransmission of non-periodic services. Furthermore, communication device 2 sets one or more listening intervals B for resource (re)selection triggers in order to detect resource reservations for periodic services. That is, communication device 2 sets listening intervals A and B for resource (re)selection triggers. Moreover, communication device 2 listens in listening intervals A and B and detects resources reserved by other D2D communications in the selection candidate time slot set.

[0118] Figure 10 This indicates a comparison of the results regarding the reduction in power consumption. For example... Figure 2 As shown, full-range listening involves listening to all resources within the listening window. The width of the listening window is 1000 subframes. Partial listening is as follows... Figure 3 or Figure 8 As shown, listening is conducted in one or more listening zones (B). The number of listening zones set within the listening window is four, and the width of each listening zone is five subframes / slots. In this case, the number of subframes / slots belonging to listening zone (B) is 20.

[0119] like Figure 5 As shown, the implementation involves listening within listening interval A. Here, it is envisioned that the width of listening interval A is maximized. That is, the first slot selected from the candidate slot set is the next slot after the slot triggered by the resource (re)selection. Furthermore, the time Tp required for the listening process is less than the time of one slot. In this case, the starting slot of listening interval A is "m+1-W", and the ending slot of listening interval A is "m-1". Therefore, in Figure 4 When the width W of the scheduling window shown is 32 time slots, the number of time slots belonging to the listening interval A is 30.

[0120] Furthermore, to simplify the study, the width of the time slot is the same as the width of the subframe, which is 1 second. Figure 5 , Figure 7 , Figure 8 The parameter T0 shown is 1000 m seconds.

[0121] In full-range listening, listening occurs over 1000 subframes. In contrast, in partial listening, listening occurs over 20 subframes / time slots. Therefore, the power consumption of partial listening is reduced by 98% compared to full-range listening. In one implementation, listening occurs over 30 time slots. Therefore, the power consumption of this implementation is reduced by 97% compared to full-range listening. When combining partial listening and the implementation, listening occurs over 50 time slots. Therefore, the power consumption of combining both methods is reduced by 95% compared to full-range listening.

[0122] In this way, the power consumption of the implementation method is significantly reduced compared to full-range monitoring. Furthermore, the power consumption of the implementation method (and the case combining both methods) is roughly the same as that of partial monitoring. On the other hand, the implementation method is capable of detecting... Figure 4 The resource reservation shown is used for retransmission of non-periodic services, thus reducing packet conflicts compared to partial snooping.

[0123] Figure 11 This is a flowchart illustrating an example of a communication method according to an embodiment of the present invention. The processing in this flowchart is performed when the generation of a resource (re)selection trigger is predicted in the communication device 2.

[0124] In S1, communication device 2 sets a selection window corresponding to the resource (re)selection trigger. Parameters used to set the selection window (in...) Figure 5 The values ​​(T1, T2, etc.) are predetermined or notified from base station 1.

[0125] In S2, communication device 2 sets a selection candidate time slot set in the selection window. The parameters used to set the selection candidate time slot set (e.g., the number and configuration of time slots) are predetermined or notified from base station 1. For example, in... Figure 5 In the example shown, there are 5 time slots, and these time slots are consecutive. Figure 7 In the example shown, there are 4 time slots, and these time slots are not consecutive.

[0126] In S3, communication device 2 determines whether the condition "ty0 - W ≤ m - Tp" is met. ty0 represents the position of the first time slot in the candidate time slot set. W represents the width of the scheduling window for resources used to schedule retransmissions of non-periodic services. m represents the time slot that triggered the resource (re)selection. Tp represents the time required for the listening process. Then, if this condition is met, the processing of communication device 2 proceeds to S4; otherwise, the processing of communication device 2 proceeds to S10.

[0127] In S4, communication device 2 sets the listening interval A based on the resource (re)selection trigger position m, the start position ty0 of the candidate time slot set, and the width W of the scheduling window. The start position of listening interval A is the time slot after W back from the start position ty0 of the candidate time slot set. The end position of listening interval A is the time slot after the processing time Tp back from the resource (re)selection trigger m. However, the end position of listening interval A can also be the time slot immediately preceding the resource (re)selection trigger m.

[0128] In S5, communication device 2 listens within listening interval A. Specifically, for each resource within listening interval A, control information (e.g., SCI) is decoded, and the received power (e.g., RSRP of PSCCH, RSRP of PSSCH, or RSSI) is calculated. The listening results are stored in memory.

[0129] In steps S6 and S7, communication device 2 extracts resources reserved by other communication devices and whose received power exceeds a threshold based on the listening results. The initial value of the threshold is predetermined or notified from base station 1. Furthermore, when resources for D2D communication are reserved, the communication device (here, communication device Z) notifies surrounding devices of the reservation using SCI. At this time, the notification reaches all communication devices located around communication device Z. Therefore, communication device 2 can detect resource reservations through listening. Then, communication device 2 excludes resources extracted based on reservations and received power from the selected candidate time slot set.

[0130] In S8, communication device 2 determines whether there are remaining resources exceeding a predetermined amount in the candidate time slot set. The predetermined amount is, for example, 20% of the total resources in the initial state of the candidate time slot set. Then, if the remaining resources are less than the predetermined amount, in S9, communication device 2 increases the threshold. At this time, the threshold increases by, for example, 3 dB. Afterward, the processing of communication device 2 returns to S6. That is, the processes S6 to S9 are repeated until the remaining resources in the candidate time slot set become greater than or equal to the predetermined amount. Then, when the remaining resources in the candidate time slot set become greater than or equal to the predetermined amount, the processing of communication device 2 proceeds to S10.

[0131] In S10, communication device 2 selects resources for data transmission from the remaining resources in the candidate time slot set. Then, communication device 2 uses the selected resources to transmit data.

[0132] Furthermore, the processes S1 to S9 are performed, for example, before the resource (re)selection trigger. In this case, the timing of the resource (re)selection trigger is predicted, and the processes S1 to S9 are performed based on this prediction. Moreover, when the communication device 2 periodically transmits signals, it can easily predict the timing of the next resource (re)selection trigger. For example, the communication device 2 performs a process of continuously transmitting periodically using the same frequency resources before the counter expires, based on a reselection counter randomly set within a certain range (e.g., 5 to 15 times). In this case, the timing of the counter expiration is the timing of the resource (re)selection trigger, which can be easily predicted.

[0133] Alternatively, communication device 2 can also execute the processes S1 to S9 when a resource (re)selection trigger is generated. However, in this case, communication device 2 always stores a signal indicating the state of the radio waves in its memory. Then, when a resource (re)selection trigger is generated, the signals stored in the memory are used to execute the processes S1 to S9.

[0134] Figure 12This illustrates an example of the structure of base station 1. Base station 1 is, for example, a next-generation NodeB (gNB). Furthermore, as... Figure 12 As shown, base station 1 includes a control unit 11, a storage unit 12, a network interface 13, a wireless transmitter 14, and a wireless receiver 15. Additionally, base station 1 may also include components not present in... Figure 12 Other circuits or functions shown in the diagram.

[0135] The control unit 11 controls the cellular communication provided by the base station 1. Additionally, the control unit 11 can also determine parameters for D2D communication (i.e., sidelink communication) performed by the communication device 2. For example, the control unit 11 can determine parameters representing... Figure 5 The parameters T1 and T2 of the selection window configuration shown, the parameter Y representing the number of time slots in the candidate time slot set, and the parameter W representing the size of the scheduling window, etc., are used. In this case, the determined parameters are notified to the communication device 2, for example, via PDCCH (Physical Downlink Control Channel) or RRC (Radio Resource Control). Furthermore, in this embodiment, the control unit 11 is implemented by a processor. However, a portion of the functionality of the control unit 11 can also be implemented using hardware circuitry.

[0136] The storage unit 12 stores the software program executed by the processor. Furthermore, the storage unit 12 stores data and information required to control the operation of the base station 1. The storage unit 12 is implemented, for example, using a semiconductor memory. The network interface 13 provides an interface for connecting to the core network. That is, the base station 1 can connect to other base stations 1 or the network management system controlling the base station 1 via the network interface 13.

[0137] The wireless transmitter 14 transmits cellular communication wireless signals according to instructions provided by the control unit 11. Specifically, the wireless transmitter 14 transmits downlink signals to the communication device 2 located within the cell. The wireless receiver 15 receives cellular communication wireless signals according to instructions provided by the control unit 11. Specifically, the wireless receiver 15 receives uplink signals transmitted from the communication device 2 located within the cell. Furthermore, cellular communication is provided, for example, using the 2.4 GHz frequency band and / or the 4 GHz frequency band.

[0138] Figure 13This illustrates an example of the structure of communication device 2. Communication device 2 supports both cellular communication and D2D communication. Furthermore, D2D communication is implemented using a different frequency band than cellular communication. For example, D2D communication can be provided using the 6GHz frequency band. However, D2D communication can also share the same frequency band as the uplink of cellular communication. Moreover, communication device 2 includes a control unit 21, a storage unit 22, a wireless transmitter 23, a wireless receiver 24, a wireless transmitter 25, and a wireless receiver 26. Additionally, communication device 2 may also include components not specified in the text. Figure 13 Other circuits or functions shown in the diagram.

[0139] The control unit 21 controls the cellular communication and D2D communication provided by the communication device 2. In this embodiment, the control unit 21 is implemented by a processor. In this case, the control unit 21 provides the function of controlling cellular communication and D2D communication by executing a software program stored in the storage unit 22. For example, the control unit 21 executes a program that describes... Figure 11 The flowchart shown illustrates the processing procedure. In this case, the control unit 21, for example, executes a trigger based on the resources provided to the communication device 2. Figure 11 The flowchart shown illustrates the processing. Furthermore, the control unit 21 provides functions for a listening interval determination unit to determine the listening interval and a resource determination unit to determine the resources used for transmitting D2D signals from the selected candidate time slot set. Additionally, some of the functions of the control unit 21 can also be implemented via hardware circuitry.

[0140] The storage unit 22 stores the software program executed by the processor. Additionally, the storage unit 22 stores data and information required to control the operation of the communication device 2. Furthermore, the storage unit 22 is implemented, for example, using a semiconductor memory.

[0141] The wireless transmitter 23 transmits cellular communication wireless signals according to instructions provided by the control unit 21. That is, the wireless transmitter 23 transmits uplink signals to the base station 1. The wireless receiver 24 receives cellular communication wireless signals according to instructions provided by the control unit 21. That is, the wireless receiver 24 receives downlink signals transmitted from the base station 1. At this time, the wireless receiver 24 sometimes receives parameters related to eavesdropping from the base station 1.

[0142] The wireless transmitter 25 transmits D2D communication wireless signals according to instructions provided by the control unit 21. That is, the wireless transmitter 25 uses resources selected by the communication device 2 itself to transmit D2D signals to other communication devices. The wireless receiver 26 receives D2D communication wireless signals according to instructions provided by the control unit 21. That is, the wireless receiver 26 receives D2D signals transmitted from other communication devices. In this embodiment, the D2D signals include V2X data and V2X control information. Furthermore, Figure 11The listening process shown in S5 is performed by the wireless receiver 26. That is, the wireless receiver 26 has a listening unit that listens within the listening range. In this case, the wireless receiver 26 may also have a processor that performs the listening process.

[0143] In addition, Figure 13 In the example shown, the wireless communication unit for cellular communication and the wireless communication unit for D2D communication are arranged separately, but the communication device 2 is not limited to this structure. For example, the wireless communication unit for cellular communication and the wireless communication unit for D2D communication can be shared. In this case, the wireless transmitter 25 and the wireless receiver 26 are not required. Moreover, the wireless transmitter 23 transmits cellular signals and D2D signals, and the wireless receiver 24 receives cellular signals and D2D signals. In addition, the wireless receiver 24 includes a listening unit.

[0144] <Changes>

[0145] In Release 16NR-V2X, it is possible to set priorities for D2D communication reservations. For example, Figure 14 As shown, communication device 2 listens in listening interval A and selects resource R1 from time slot ty0+2 in the candidate time slot set. However, resource R1 or a portion of R1 is subsequently reserved by other communication devices with higher priority.

[0146] In this situation, communication device 2 cannot use resource R1. Therefore, when it is detected that another communication device with a higher priority has reserved resource R1, communication device 2 releases resource R1 and selects another resource from the selection candidate time slot set. Figure 14 In time slot ty0+4, resource R2 was reselected. Then, communication device 2 used the reselected resource R2 to transmit the D2D signal.

[0147] However, in order to detect reservations from other communication devices with higher priority, communication device 2 needs to continue listening even after listening interval A ends. Specifically, communication device 2 needs to continue listening until the interval where D2D signals can be transmitted ends. Therefore, preferably, communication device 2 continues listening until the selection of the candidate time slot set ends. Note that communication device 2 can decide whether to perform the above reselection for each resource pool.

[0148] Additionally, communication device 2 can also predict the location of the trigger slot used to determine the selection of the candidate time slot set. The trigger slot represents the time slot used to generate a resource (re)selection trigger or resource (re)selection indication. Here, it is assumed that communication device 2 transmits D2D signals with a period P. In this case, when communication device 2 transmits a D2D signal using a certain time slot, it can easily predict the timing of transmitting the next D2D signal. Figure 15 In the example shown, a D2D signal is transmitted in time slot m-P. Therefore, communication device 2 predicts time slot m as the next triggering time slot.

[0149] Once the trigger slot is determined, a candidate slot set is set. Furthermore, when a candidate slot set is set, such as... Figure 5 The diagram shows the determination of the listening interval A for non-periodic services, and as shown... Figure 8 The listening interval B used for periodic services is determined as shown. That is, by predicting the next trigger slot, communication device 2 can predetermine the listening interval before actually generating the resource (re)select trigger. Therefore, communication device 2 can obtain the listening results before sending the next D2D signal. Alternatively, communication device 2 can also use a counter to predict the next trigger slot.

[0150] Furthermore, for the initial transmission of periodic services or non-periodic services, the data transmission timing can be predicted based on certain assumptions or preconditions. In this case, communication device 2 can also set and select a set of candidate time slots based on this prediction. Moreover, when a resource pool is prepared that allows for random resource selection, communication device 2 can select resources without listening.

[0151] When the timing of resource reselection cannot be predicted, communication device 2 may have difficulty performing operations based on... Figure 3 or Figure 8 Listening based on the transmission cycle shown. For example, it is difficult to perform periodic-based listening in the following situations.

[0152] (1) Changes in business model

[0153] (2) The resource pool was reconstructed by the base station.

[0154] (3) The selected resources do not meet the requirements (e.g., the resource size is too small or the waiting time is too long).

[0155] In this scenario, communication device 2 can select the required resources from a resource pool capable of random resource selection without eavesdropping. Furthermore, in periodic services, communication device 2 can also randomly select resources for the initial data transmission, and for subsequent data transmissions, utilize... Figure 3 or Figure 8 The shown portion is used to listen for and select resources.

[0156] Label Explanation

[0157] 1 base station

[0158] 2 communication device

[0159] 11 Control Department

[0160] 12 Storage Department

[0161] 13 Network Interface

[0162] 14 Wireless Transmission Unit

[0163] 15. Wireless Receiver

[0164] 21 Control Department

[0165] 22 Storage Department

[0166] 23, 25 Wireless Transmission Unit

[0167] 24, 26 Wireless Receiving Unit

[0168] 100 Wireless Communication System

Claims

1. A communication device that supports D2D communication, i.e., device-to-device communication, wherein, The communication device includes: The listening interval determination unit determines the listening interval to be listened to based on the position of the first time slot in the candidate time slot set and information related to the transmission of non-periodic services. The candidate time slot set includes time slots set for transmitting D2D signals. The listening unit listens within the listening range determined by the listening range determination unit; as well as The resource decision-making unit determines the resources for transmitting D2D signals from the selected candidate time slot set based on the listening results of the listening unit.

2. The communication device according to claim 1, characterized in that, The communication device further includes a receiving unit that receives information from the base station related to the transmission of non-periodic services.

3. The communication device according to claim 2, characterized in that, The starting position of the listening interval is determined by retrospectively counting back a specified time slot from the earliest time slot, based on the information related to the transmission of non-periodic services.

4. The communication device according to claim 3, characterized in that, The specified time represents the range of resources that can be reserved in a communication system containing the communication device for retransmission corresponding to the initial transmission of D2D data.

5. The communication device according to claim 1, characterized in that, The listening interval determination unit determines the end position of the listening interval based on the data transmission instruction, wherein the data is transmitted using the resources determined by the resource determination unit.

6. The communication device according to claim 5, characterized in that, The end position of the listening interval is the time slot after a specified time following the transmission instruction.

7. The communication device according to claim 6, characterized in that, The specified time refers to the time required for the listening unit to conduct listening.

8. The communication device according to claim 1, characterized in that, The listening unit detects control information indicating resources reserved by other communication devices by decoding the received signals during the listening process. The resource decision unit excludes resources represented by the control information from the resources belonging to the selection candidate time slot set, and determines the resources for transmitting D2D signals from the remaining resources in the selection candidate time slot set.

9. The communication device according to any one of claims 1 to 8, characterized in that, The listening interval determination unit sets a second listening interval by tracing back from the selected candidate time slot set to the position after a pre-specified D2D service transmission period in the communication system containing the communication device. The listening unit listens in the listening interval and the second listening interval. Based on the listening results of the listening unit, the resource decision unit determines the resources for transmitting D2D signals from the selected candidate time slot set.

10. A communication method, wherein the communication method is performed by a communication device supporting D2D communication, i.e., device-to-device communication, characterized in that, The communication method includes: Based on the position of the first slot in the candidate slot set and information related to the transmission of non-periodic services, the listening interval for listening is determined, wherein the candidate slot set includes slots set for transmitting D2D signals. Listening within the listening range; and Based on the results of the listening, resources for transmitting D2D signals are determined from the selected candidate time slot set.

11. A communication system comprising multiple communication devices supporting D2D communication, i.e., device-to-device communication, characterized in that, The first communication device among the plurality of communication devices sends control information indicating the reserved resources to the other device. The second communication device among the plurality of communication devices determines a listening interval for listening based on the position of the earliest time slot in the candidate time slot set and information related to the transmission of non-periodic services. The candidate time slot set includes time slots set for transmitting D2D signals. Listening is performed in the listening interval. When the control information is detected during the listening, the resources represented by the control information are excluded from the resources belonging to the candidate time slot set, and the resources for transmitting D2D signals are determined from the remaining resources in the candidate time slot set.

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