Technical field
[0001]
　The present invention relates to a wireless terminal and a wireless communication system capable of direct communication between wireless terminals without going through a wireless base station.
Background technology
[0002]
　
　In recent years, assuming various use cases for wireless communication systems (which can also be called mobile communication systems) such as mobile phone systems (cellular systems), further speeding up and large capacity of wireless communication (which can also be called mobile communication) Next-generation wireless communication technology is being discussed in order to achieve this. For example, the standardization organization 3GPP (3rd Generation Partnership Project) has specifications for a communication standard called LTE (Long Term Evolution) and a communication standard called LTE-Advanced based on LTE wireless communication technology. It has already been formulated and ongoing study work is underway to expand its functionality. For example, discussions are being held on the standardization of fifth-generation mobile communication systems (also called 5G systems) that realize the contents of operational scenarios and technical requirements presented by the ITU-R (International Telecommunication Union Radiocommunication sector). ..
[0003]
　In the above discussion on standardization, the main focus is on matters related to wireless communication between wireless base stations and wireless terminals, but discussions are also being made on matters related to wireless communication between wireless terminals. For example, V2X (Vehicle-to-everything) technology is known as a technology related to wireless communication between a wireless terminal (vehicle-mounted terminal) mounted on an automobile and other wireless terminals.
[0004]
　The V2X technology is an extension of the D2D (Device-to-Device) technology defined by LTE to ITS (Intelligent Transport Systems) applications. V2X technology is a general term for technologies related to multiple communication modes in ITS. For example, V2V (Vehicle-to-Vehicle), which is a communication mode between automobiles, and automobiles and roadside units (RSUs). V2I (Vehicle-to-Infrastructure), which is a communication mode between vehicles, V2P (Vehicle-to-Pedestrian), which is a communication mode between a car and a pedestrian wireless terminal, and communication between a car and a network. V2N (Vehicle-to-Network), which is a form of communication with the device, is included. V2V may be referred to as "vehicle-to-vehicle communication", V2I may be referred to as "road-to-vehicle communication", V2P may be referred to as "vehicle-to-vehicle communication", and V2N may be referred to as "vehicle-to-vehicle network communication".
[0005]
　In V2X technology, in addition to the two modes (Mode1 and Mode2) in D2D technology, mode 3 (Mode 3) in which the wireless base station performs resource scheduling for V2X communication and the wireless terminal autonomously performs V2X communication. Mode 4 for selecting resources has been added.
Prior art literature
Non-patent literature
[0006]
Non-Patent Document 1: 3GPP TS 36.211 V15.1.0 (2018-03)
Non-Patent Document 2: 3GPP TS 36.212 V15.1.0 (2018-03)
Non-Patent Document 3: 3GPP TS 36.213 V15.1.0 (2018-03)
Non -Patent Document Document 4: 3GPP TS 36.300 V15.1.0 (2018-03)
Non-Patent Document 5: 3GPP TS 36.321 V15.1.0 (2018-03)
Non-Patent Document 6: 3GPP TS 36.322 V15.0.1 (2018-04)
Non-Patent Document 7 : 3GPP TS 36.323 V14.5.0 (2017-12)
Non-Patent Document 8: 3GPP TS 36.331 V15.1.0 (2018-03)
Non-Patent Document 9: 3GPP TS 36.413 V15.1.0 (2018-03)
Non-Patent Document 10: 3GPP TS 36.423 V15.1.0 (2018-03)
Non-Patent Document 11: 3GPP TS 36.425 V14.1.0 (2018-03)
Non-Patent Document 12: 3GPP TS 37.340 V15.1.0 (2018-03)
Non-Patent Document 13: 3GPP TS 38.201 V15.0.0 (2017-12)
Non-Patent Document 14: 3GPP TS 38.202 V15.1.0 (2018-03)
Non-Patent Document 15: 3GPP TS 38.211 V15.1.0 (2018-03)
Non-Patent Document 16: 3GPP TS 38.212 V15.1.1 (2018-04)
Non -Patent Document Document 17: 3GPP TS 38.213 V15.1.0 (2018-03)
Non-Patent Document 18: 3GPP TS 38.214 V15.1.0 (2018-03)
Non-Patent Document 19: 3GPP TS 38.215 V15.1.0 (2018-03)
Non-Patent Document 20 : 3GPP TS 38.300 V15.1.0 (2018-03)
Non-Patent Document 21: 3GPP TS 38.321 V15.1.0 (2018-03)
Non-Patent Document 22: 3GPP TS 38.322 V15.1.0 (2018-03)
Non-Patent Document 23: 3GPP TS 38.323 V15.1.0 (2018-03)
Non-Patent Document 24: 3GPP TS 38.331 V15.1.0 (2018-03)
Non-Patent Document 25: 3GPP TS 38.401 V15.1.0 (2018-03)
Non-Patent Document 26: 3GPP TS 38.410 V0.9.0 (2018-04)
Non-Patent Document 27: 3GPP TS 38.413 V0.8.0 (2018-04)
Non-Patent Document 28: 3GPP TS 38.420 V0.8.0 (2018-04)
Non-Patent Document 29: 3GPP TS 38.423 V0.8.0 (2018-04)
Non -Patent Document Document 30: 3GPP TS 38.470 V15.1.0 (2018-03)
Non-Patent Document 31: 3GPP TS 38.473 V15.1.1 (2018-04)
Non-Patent Document 32: 3GPP TR 38.801 V14.0.0 (2017-04)
Non-Patent Document 33 : 3GPP TR 38.802 V14.2.0 (2017-09)
Non-Patent Document 34: 3GPP TR 38.803 V14.2.0 (2017-09)
Non-Patent Document 35: 3GPP TR 38.804 V14.0.0 (2017-03)
Non-Patent Document 36: 3GPP TR 38.900 V14.3.1 (2017-07)
Non-Patent Document 37: 3GPP TR 38.912 V14.1.0 (2017-06)
Non-Patent Document 38: 3GPP TR 38.913 V14.3.0 (2017-06)
Non-Patent Document 39: R. Molina-Masegosa and J. Gozalvez, “LTE-V for Sidelink 5G V2X,” IEEE Vehicular Technology Magazine, Vol. 12, pp. 30-39, Dec. 2017.
Outline of the invention
Problems to be solved by the invention
[0007]
　In mode 4 of the V2X technology, the wireless terminal operates so as to autonomously select a wireless resource for V2X communication. More specifically, a wireless terminal participating in V2X communication can be used to transmit a V2X signal by observing wireless resources in a range of selection windows (also referred to as Selection Window) that repeatedly arrive at a predetermined cycle. Generate information (which can also be called a resource pool) about one or more candidate free resources (CSR), and use radio resources (which can also be called CSR) randomly selected from the resource pool. The V2X signal is transmitted.
[0008]
　When the number of CSRs contained in the resource pool is less than the threshold value (for example, when the ratio of unused CSRs among the CSRs contained in the selection window is less than 20%), the conditions for selecting CSRs are relaxed. The process of setting the resource pool is repeated again.
[0009]
　When the number of wireless terminals participating in V2X communication increases, the number of CSRs included in the resource pool can be reduced by randomly selecting wireless resources from each of the plurality of wireless terminals. Moreover, the wireless terminal in V2X communication may occupy (also referred to as reservation) the selected wireless resource over a plurality of selection windows by selecting a resource once.
[0010]
　Therefore, in V2X communication, the delay of V2X communication can be increased by repeating the resource pool setting process. The same applies to wireless terminals that have an urgent need to transmit information.
[0011]
　However, in the discussion on the standardization of V2X communication, the fact is that the discussion on the problem that the delay of V2X communication can increase has not progressed so much, and a sufficient solution has not been presented.
[0012]
　An object of the present disclosure technique is to provide a wireless terminal and a wireless communication system capable of effectively suppressing delay in a wireless communication system capable of selecting a wireless resource based on a sensing result such as V2X communication.
Means to solve problems
[0013]
　According to one aspect of the present disclosure, when a wireless terminal configured to select a wireless resource for transmitting a signal based on a sensing result and detects a predetermined first event, The radio resource belonging to the first reserved area is configured to be excluded from the selection target.
Effect of the invention
[0014]
　According to one aspect of the disclosed technology, delays in wireless communication systems that can select wireless resources based on sensing results, such as V2X communications, can be effectively suppressed.
A brief description of the drawing
[0015]
FIG. 1 is a diagram showing an example of a configuration of a wireless communication system according to a first embodiment.
FIG. 2 is a diagram showing an example of arrangement of wireless resources for V2X communication in a wireless channel configuration of a wireless terminal.
FIG. 3 is a diagram showing an example of a sub-channel configuration in a side link channel.
FIG. 4 is a diagram showing an example of signal mapping in a sub-channel configuration of a side link channel.
FIG. 5 is a diagram showing an example of sensing in V2X communication.
FIG. 6 is a diagram showing an example of a first reserved area in the second time window of the side link channel according to the first embodiment.
FIG. 7 is a diagram showing an example of a processing flow in the wireless terminal according to the first embodiment.
FIG. 8 is a diagram showing an example of a first reserved area and a second reserved area in the second time window of the side link channel according to the first embodiment.
FIG. 9 is a diagram showing an example of a first reserved area and a second reserved area in the second time window of the side link channel according to the second embodiment.
FIG. 10 is a diagram showing an example of a processing flow in the wireless terminal according to the second embodiment.
FIG. 11 is a diagram showing an example of a time range in which an emergency event is applied in the side link channel according to the third embodiment.
FIG. 12A is a diagram showing an example of a processing flow in the wireless terminal according to the third embodiment (No. 1).
FIG. 12B is a diagram showing an example of a processing flow in the wireless terminal according to the third embodiment (No. 2).
FIG. 13 is a diagram showing an example of a hardware configuration of a wireless terminal and a wireless base station in a wireless communication system.
Mode for carrying out the invention
[0016]
　Hereinafter, embodiments (hereinafter, also referred to as embodiments and examples) for carrying out the present invention will be described with reference to the drawings. The configuration of the embodiment shown below shows an example for embodying the technical idea of ​​the present invention, and is not intended to limit the present invention to the configuration of the present embodiment. It is equally applicable to other embodiments included in the scope of. For example, the names of V2X communication, V2V communication, etc. may be changed in future discussions on standardization of 4G systems and 5G systems. It is also possible that the names of various channels such as PSCCH (Physical Sidelink Control CHannel) and PSCH (Physical Sidelink Shared CHannel) may be changed in future discussions on standardization of 4G systems and 5G systems. Moreover, SCI (Sidelink Control Information), TB (Transport Block), RB (Resource Block), RS (Reserved Sub-channel), RA (1 st Reserved Area), the various names such CSR (Candidate Single-subframe Resource) However, the name may be changed in future discussions on standardization of 4G systems and 5G systems. It should be noted that the present disclosure is not intended to limit the components of the invention to those using these names.
[0017]
　Needless to say, the examples shown below may be combined as appropriate. Here, all the contents of Non-Patent Document 1 to Non-Patent Document 38 are incorporated herein by reference. The release numbers of Non-Patent Document 1 to Non-Patent Document 38 are examples. That is, Non-Patent Document 1 to Non-Patent Document 38 corresponding to the latest release number published at the time of filing of the present disclosure are also incorporated herein by reference. In the present disclosure, V2X communication is an example of a wireless communication system capable of selecting a wireless resource based on a sensing result. V2X communication may be referred to as device-to-device communication, for example.
[0018]
　 In Example 1, a wireless communication system having a wireless terminal configured to select a wireless resource for transmitting a signal based on a sensing result is exemplified. According to one aspect of the first embodiment, when the radio terminal detects a predetermined first event (which may also be called an emergency event), the radio resource belonging to the first reserved area is excluded from the selection target. Can be configured. In other words, the wireless terminal that has detected the first event suppresses the transmission of a signal using the wireless resource belonging to the first reserved area. As a result, the wireless terminal having the need to transmit urgent information (which may also be referred to as the wireless terminal in the emergency mode) can communicate using the wireless resource belonging to the first reserved area. According to another aspect of Example 1, the wireless terminal may be configured to output an emergency event if there is a need to transmit urgent information. By outputting an emergency event, the wireless terminal in the emergency mode causes another wireless terminal (which may also be referred to as a wireless terminal in the non-emergency mode) to operate so as to exclude the wireless resource belonging to the first reserved area from the selection target. .. As a result, delays in V2X communication (which may be referred to as inter-device communication) of wireless terminals that need to transmit urgent information can be effectively suppressed.
[0019]
　FIG. 1 is a diagram showing an example of the configuration of the wireless communication system 1 according to the first embodiment. The wireless communication system 1 illustrated in FIG. 1 has a wireless terminal 10-1 and a wireless terminal 10-2, and a wireless base station 20. The wireless terminal 10-1 and the wireless terminal 10-2 may also be referred to as a wireless terminal 10 when there is no particular need to distinguish them. In FIG. 1, the wireless terminal 10 may be an in-vehicle terminal mounted on an automobile or a wireless terminal mounted on a mobile body other than the automobile. For example, the wireless terminal 10 may be a wireless terminal mounted on a moving body such as a railroad vehicle, a ship, or an airplane. The V2X communication in the present disclosure can be performed in wireless terminals mounted on these wide range of mobiles. Alternatively, the wireless terminal 10 may be a wireless terminal mounted on a non-moving object such as a roadside machine. The V2X communication in the present disclosure can also be executed in a wireless terminal mounted on a non-moving object such as a traffic light (which may be referred to as a roadside machine).
[0020]
　It should be noted that the radio terminal 10 and the radio base station 20 illustrated in FIG. 1 are abstract representations of a plurality of properties (which may also be referred to as sides and viewpoints). For example, the radio base station 20 may be configured by a combination of a plurality of devices. Although two wireless terminals 10 (that is, wireless terminals 10-1 and 10-2) are illustrated in FIG. 1, the wireless communication system 1 may have three or more wireless terminals 10. In other words, the wireless base station 20 may establish a wireless connection with a plurality of wireless terminals 10.
[0021]
　The wireless terminals 10-1 and 10-2 illustrated in FIG. 1 perform wireless communication conforming to wireless communication standards such as LTE and 5G within the range of the cell 30 formed by the wireless base station 20. It can be done with 20. In the present disclosure, the cell 30 formed by the radio base station 20 may be appropriately read as a radio area, a sector, a radio area, a radio service area, a macro cell, a small cell, a pico cell, or the like. It should be noted that the size of the cell 30 is not limited to the size illustrated in FIG.
[0022]
　In FIG. 1, the wireless terminals 10-1 and 10-2 are located in a range 40 (which may also be referred to as a V2X communication range) capable of mutually performing V2X communication (which may be referred to as V2V communication). Here, V2X communication is wireless communication (also referred to as inter-device wireless communication) in which wireless signals can be directly transmitted and received between the wireless terminal 10-1 and the wireless terminal 10-2 without going through the wireless base station 20. Good) is an example. For example, the wireless terminals 10-1 and 10-2 may belong to the range 40 in which V2X communication is possible when the distance between them is less than a predetermined value. The range 40 capable of V2X communication may be changed in position with the movement of the wireless terminals 10-1 and 10-2, and may be formed outside the range of the cell 30 formed by the wireless base station 20. It should be noted that the size of the range 40 in which V2X communication is possible is not limited to the size illustrated in FIG.
[0023]
　The wireless terminal 10-1 and the wireless terminal 10-2 perform sensing in a first time window (which may also be referred to as a Sensing Window) having a predetermined first time length, and transmit a V2X communication signal based on the sensing result. It is configured to select radio resources to do so.
[0024]
　FIG. 2 is a diagram showing an example of arrangement of wireless resources for V2X communication in the wireless channel configuration of the wireless terminal 10. FIG. 2 shows the time axis in the horizontal direction and the frequency axis in the vertical direction. The radio channel configuration illustrated in FIG. 2 is based on the LTE uplink radio channel configuration. That is, in the radio channel configuration illustrated in FIG. 2, PUCCHs (Physical Uplink Control CHannels) are arranged at the upper and lower ends in the frequency axis direction, and PUSCHs (Physical Uplink Shared CHannels) are arranged between the two PUCCHs. ..
[0025]
　In the example of FIG. 2, a side link channel (Sidelink Channel), which is a radio resource for V2X communication, is further arranged at an arbitrary position of the PUSCH in the frequency axis direction. The side link channels are further subdivided into L subchannels in the frequency axis direction, and PSCCH (Physical Sidelink Control CHannel) that can be used for transmission of control signals and PSCH (Physical Sidelink Shared CHannel) that can be used for transmission of data signals. And can be included. There are several variations in the subchannel configuration in the side link channel. For example, in the first method (which may also be referred to as Adjacent PSCCH + PSSCH Scheme), the radio resources that can be used for PSCCH and the radio resources that can be used for PSSCH are arranged so as to be adjacent to each other. In the second method (which may also be referred to as Nonadjacent PSCCH + PSSCH Scheme), the radio resources that can be used for PSCCH and the radio resources that can be used for PSCH are not always arranged so as to be adjacent to each other. The setting information regarding the configuration of the side link channel for V2X communication may be stored in advance in the memory of the wireless terminal 10, or may be set by wireless communication from the wireless base station 20. For example, the wireless terminal 10 is an RRC (Radio Resource) including setting information regarding the configuration of a side link channel for V2X communication from the wireless base station 20. Control) message may be received. In other words, the radio base station 20 may be configured to transmit an RRC message containing configuration information regarding the configuration of a side link channel for V2X communication. Such setting information may include, for example, setting information regarding the first reserved area according to the present disclosure. In other words, the RRC message may include setting information regarding the first reserved area according to the present disclosure. The setting information regarding the first reserved area may include, for example, information used by the wireless terminal 10 when specifying the position and size of the first reserved area.
[0026]
　FIG. 3 is a diagram showing an example of a sub-channel configuration in the side link channel. The sub-channel configuration shown in FIG. 3 is exemplified by four sub-channels (F10-A, F10-B, F10-C, F10-D), showing the frequency axis in the vertical direction and in the horizontal direction. Shows the time axis. That is, in FIG. 3, four subchannels are arranged in the vertical direction, and subframes having a predetermined time length are arranged in the horizontal direction.
[0027]
　The sub-channel configuration shown in FIG. 3 is based on the above-mentioned first method. That is, each subchannel (F10-A, F10-B, F10-C, F10-D) is a first radio resource (F10-A1, F10-B1, F10-C1, F10-D1) that can be used for PSCCH. And the second radio resource (F10-A2, F10-B2, F10-C2, F10-D2) that can be used for PSSCH are arranged so as to be adjacent to each other.
[0028]
　In FIG. 3, the first radio resource is a radio resource used for transmission of SCI (Sidelink Control Information) which is a control signal or TB (Transport Block) which is a data signal. For example, 2 It consists of two RBs (Resource Blocks). In other words, the first radio resource can be a PSCCH or a PSCH.
[0029]
　On the other hand, the second radio resource is a radio resource that can be used only for the transmission of TB, which is a data signal, and is composed of one or more RBs (for example, n RBs). In other words, the second radio resource can only be mapped to the PSSCH.
[0030]
　FIG. 4 is a diagram showing an example of signal mapping in a sub-channel configuration of a side link channel. The side link channel shown in FIG. 4 is composed of four subchannels (F10-A, F10-B, F10-C, F10-D) as in the example in FIG. The number of sub-channels is merely an example, and the side link channel may be composed of 4 or more or less than 4 sub-channels.
[0031]
　FIG. 4 shows the frequency axis in the vertical direction and the time axis in the horizontal direction. That is, in FIG. 4, four subchannels are arranged in the vertical direction, and subframes having a predetermined time length (for example, 1 ms) are arranged in the horizontal direction. Further, in the horizontal direction of FIG. 4, a second time window (which may also be referred to as a selection window) having a second time length including a plurality of subframes is arranged.
[0032]
　In the signal mapping example shown in FIG. 4, signals are sent to the third subframe (SF-1), the sixth subframe (SF-2), and the ninth subframe (SF-3) from the left end. Is mapped. It should be noted that the subframe is a concept in the time axis direction, and in other words, it is a concept that abstracts the position of the radio resource in the frequency axis direction.
[0033]
　In FIG. 4, in the third subframe (SF-1), the control signal (SCI-1) is mapped to the first radio resource (F10-A1) of the first subchannel (F10-A) from the upper end. ing. Then, the data signal (TB-1) associated with the control signal (SCI-1) is the second radio resource (F10-A2) of the first subchannel (F10-A) and the second subchannel (F10). -B) is mapped to the first radio resource (F10-B1) and the second radio resource (F10-B2). That is, the data signal (TB-1) is mapped over two subchannels (F10-A, F10-B). For example, the data signal (TB-1) may be mapped over three or more subchannels. The control signal (SCI-1) may include, for example, information on the position and length of the radio resource to which the data signal (TB-1) is mapped, information on the modulation method of the data signal (TB-1), and the like. ..
[0034]
　Further, in FIG. 4, in the sixth subframe (SF-2), the control signal (SCI-2) is transmitted to the first radio resource (F10-C1) of the third subchannel (F10-C) from the upper end. It is mapped. Then, the data signal (TB-2) associated with the control signal (SCI-2) is mapped to the second radio resource (F10-C2) of the third subchannel (F10-C). The control signal (SCI-2) may include, for example, information on the position and length of the radio resource to which the data signal (TB-2) is mapped, information on the modulation method of the data signal (TB-2), and the like. ..
[0035]
　Further, in FIG. 4, in the ninth subframe (SF-3), the control signal (SCI-3) is sent to the first radio resource (F10-B1) of the second subchannel (F10-B) from the upper end. It is mapped. Then, the data signal (TB-3) associated with the control signal (SCI-3) is the second radio resource (F10-B2) of the second subchannel (F10-B) and the third subchannel (F10). -C) first radio resource (F10-C1) and second radio resource (F10-C2), fourth subchannel (F10-D) first radio resource (F10-D1) and second radio resource (F10-D1) It is mapped to F10-D2). The control signal (SCI-3) may include, for example, information on the position and length of the radio resource to which the data signal (TB-3) is mapped, information on the modulation method of the data signal (TB-3), and the like. ..
[0036]
　As illustrated in FIG. 4, in the side link channel, the control signal (SCI-1, SCI-2, SCI-3) and the data signal (TB-1, TB-2, TB-3) are paired. Is mapped to a radio resource. These paired control signals and data signals may be mapped to adjacent radio resources or may be mapped to non-adjacent radio resources, as illustrated in FIG. That is, the example in FIG. 4 is only an example of the above-mentioned first method (which may also be referred to as Adjacent PSCCH + PSSCH Scheme). The technique of the present disclosure may also be applied to a second method (also referred to as Nonadjacent PSCCH + PSSCH Scheme).
[0037]
　The wireless terminal 10 performs sensing in order to select a wireless resource to be used for V2X communication from the sub-channel configuration of the side link channel. For example, the wireless terminal 10 performs sensing in a first time window (which may also be referred to as a Sensing Window) having a predetermined first time length, and determines a wireless resource that is likely to be unused based on the sensing result. , Radio resources are randomly selected from a group of radio resources (which may also be called a resource pool) determined to be unused.
[0038]
　FIG. 5 is a diagram showing an example of sensing in V2X communication. In FIG. 5, it is assumed that a packet to be transmitted by V2X communication is generated in the wireless terminal 10 at the time point T. The wireless terminal 10 may be unused from the resource pool in the second time window (also referred to as Selection Window) (F10-10) having a predetermined second time length (eg, 100 ms (= 100 subframes)). Randomly select high-quality radio resources. In other words, the wireless terminal 10 randomly selects wireless resources that can be used for V2X communication from the resource pool in the second time window (F10-10). The resource pool used at that time is set based on the result of sensing executed before the time of the second time window (F10-10) in which the radio resource is selected.
[0039]
　For example, the resource pool of the second time window (F10-10) has a first time length (for example, 1000 ms (= 1000 subframes) (= 10 Selection Windows)) and is also referred to as a first time window (Sensing Window). It may be set based on the result of sensing performed in). The first time window may include a plurality of second time windows (F10-0 to F10-9), as shown in FIG. In FIG. 5, the first time window includes ten second time windows and has a time length of 1000 ms (1 second).
[0040]
　In the resource pool of the second time window (F10-10), radio resource candidates (which may also be called CSR (Candidate Single-subframe Resource)) are set for each subchannel for each subframe included in the second time window. To. The wireless terminal 10 uses the wireless resource for each wireless resource candidate included in the second time window based on the sensing results in the plurality of second time windows (F10-0 to F10-9) included in the first time window. Determine if the candidate can be used for V2X communication.
[0041]
　In FIG. 5, the wireless terminal 10 has a wireless resource candidate (CSR (T)) in each of the plurality of second time windows (F10-0 to F10-9) included in the first time window before the time point T when the packet is generated. ))) Corresponding radio resource candidates (CSR (T-1000) to CSR (T-100)) are sensed, and the sensing result is used in determining the radio resource candidate (CSR (T)). In the example of FIG. 5, the first time window includes ten second time windows (F10-0 to F10-9), and the radio terminal 10 is a radio corresponding to a radio resource candidate (CSR (T)). By sensing the resource in the first time window, 10 sensing results are obtained. The wireless terminal 10 may calculate an average value from the values ​​shown in a plurality of sensing results obtained by sensing in the first time window.
[0042]
　In the resource pool setting, for example, the following conditions can be used. That is, [Condition 1] the mapping of the data signal to the radio resource candidate is not indicated by the control signal (SCI), and [Condition 2] the average of the measurement results of the radio resource candidate is less than the threshold value. is there. Here, the measurement result under the condition 2 may reflect the signal level of the V2X communication in the first time window, and may be, for example, RSSI (Received Signal Strength Indicator) or RSRP (Reference Signals Received Power). ), SNR (Signal-to-Noise Ration), RSRQ (Reference Signal Received Quality), and the like. For example, in FIG. 5, when the average value of the measurement results (CSR (T-1000) to CSR (T-100)) in the first time window is less than the threshold value (which may also be referred to as the selection threshold value), the second time window The radio resource candidate (CSR (T)) in the above can satisfy the condition 2. The above-mentioned condition 1 and condition 2 may be an AND condition or an OR condition. That is, in the case of the AND condition, when both the condition 1 and the condition 2 are satisfied, it can be determined that the radio resource candidate can be used for V2X communication. On the other hand, in the case of the OR condition, it can be determined that the radio resource candidate can be used for V2X communication as long as either condition 1 or condition 2 is satisfied.
[0043]
　The wireless terminal 10 may execute the above-described processing related to the resource pool setting every time the second time window of the second time length elapses, regardless of whether or not a packet is generated. Then, in the latest resource pool setting, when the ratio of the number of wireless resource candidates that can be used for V2X communication is less than a predetermined value, the wireless terminal 10 adds a predetermined value (for example, 3 dB) to the selection threshold value. , Reselection may be performed by determining whether or not the above condition 2 is satisfied. As a result, it is expected that the ratio of the number of wireless resource candidates that can be used for V2X communication will increase.
[0044]
　By the way, in the mode 4 of V2X communication, as described above, each wireless terminal 10 selects a wireless resource to be used for V2X communication based on the sensing result. Therefore, as the number of used radio resources increases, it may become difficult to find radio resource candidates that are likely to be unused. For example, the transmission timing of V2X communication can be delayed by repeating the resource pool setting process until the ratio of the number of wireless resource candidates that can be used for V2X communication becomes a predetermined value (for example, 20% of the total) or more.
[0045]
　Therefore, in the wireless communication system 1 according to the first embodiment, the first reserved area is set in the second time window of the side link channel. The wireless resource belonging to the first reserved area is excluded from the selection target of the wireless resource for V2X communication in the first wireless terminal when an emergency event is detected by the first wireless terminal among the plurality of wireless terminals 10. The emergency event is output by the second wireless terminal having the need to transmit urgent information among the plurality of wireless terminals 10. The second wireless terminal is an example of a wireless terminal 10 that has an urgent need to transmit information. That is, the wireless terminal 10 may be a first wireless terminal or a second wireless terminal depending on the situation. Alternatively, only a specific preset wireless terminal 10 may be allowed to be the second wireless terminal.
[0046]
　FIG. 6 is a diagram showing an example of a first reserved area in the second time window of the side link channel according to the first embodiment. In FIG. 6, the first reserved area (1 st Reserved Area) has 10 subframe lengths (for example, 10 ms) in the second time window (which may also be referred to as Selection Window), and is the third from the beginning of the second time window. Subframe is included as a start point, and the twelfth subframe is included as an end point. Further, in FIG. 6, the first reserved region is arranged so as to include all four sub-channels included in the side link channel in the frequency axis direction. The first reserved area illustrated in FIG. 6 is only an example of the present disclosure. For example, the first reserved area may be the same size as the second time window or smaller than the second time window in the time axis direction. Further, the first reserved region may have the same size as the side link channel in the frequency axis direction, or may be smaller than the side link channel. Further, the first reserved area may be arranged with any subframe within the range of the second time window as a starting point in the time axis direction. Further, the first reserved region may be arranged in any subchannel in the side link channel in the frequency axis direction.
[0047]
　As illustrated in FIG. 6, a plurality of radio resource candidates may belong to the first reserved area. Unless an emergency event is detected, a plurality of radio resource candidates belonging to the first reserved area can be used for each radio terminal 10. In other words, in the above-mentioned resource pool setting process, it is determined whether or not the plurality of radio resource candidates belonging to the first reserved area can be used in the same manner as the other radio resource candidates, and can be used by each radio terminal 10. However, when an emergency event is detected, the wireless terminal 10 that has detected the emergency event releases a plurality of wireless resource candidates belonging to the first reserved area from the resource pool generated by the above-mentioned resource pool setting process. As a result, the wireless terminal 10 having a need to transmit urgent information selects an wireless resource to be used for V2X communication from a plurality of wireless resource candidates belonging to the first reserved area by outputting an emergency event. be able to.
[0048]
　FIG. 7 is a diagram showing an example of a processing flow in the wireless terminal according to the first embodiment. An example of the processing flow shown in FIG. 7 may be executed, for example, at the timing when a packet to be transmitted by V2X communication is generated. Further, an example of the processing flow shown in FIG. 7 is executed when, for example, a packet to be transmitted by V2X communication exists in the buffer at the timing when the start point of the second time window (which may also be referred to as Selection Window) arrives. May be done. These are examples of the triggers for executing the processing flow shown in FIG. 7, and may be executed at other timings.
[0049]
　The wireless terminal 10 determines whether it is in the emergency mode (S101). In S101, the wireless terminal 10 may determine that it is in the emergency mode when the packet to be transmitted by V2X communication contains urgent information (which may be referred to as a packet, data, or signal) (S101). YES). On the other hand, in S101, the wireless terminal 10 may determine that it is not in the emergency mode when the packet to be transmitted by V2X communication does not include urgent information (NO in S101).
[0050]
　In addition, only the specific wireless terminal 10 (which may be referred to as a second wireless terminal) set in advance may be configured to execute the determination of the emergency mode (S101). In other words, the wireless terminal 10 other than the preset specific wireless terminal 10 may be configured to omit the execution of the emergency mode determination (S101) and transition to NO in S101. In other words, the wireless terminal 10 other than the preset specific wireless terminal 10 may be configured to start the process from S105 among the processes shown in FIG. 7. Such a difference in operation may be controlled by turning on / off a flag set in the memory included in the wireless terminal 10. For example, the wireless terminal 10 may be controlled to start the process shown in FIG. 7 from S101 when a predetermined flag stored in the memory is set to ON. For example, the wireless terminal 10 may be controlled to start the process shown in FIG. 7 from S105 when a predetermined flag stored in the memory is set to off.
[0051]
　When it is determined in S101 that the mode is an emergency mode (YES in S101), the wireless terminal 10 outputs an emergency event (S102) and selects a wireless resource to be used for V2X communication from the first reserved area (1 st Reserved Area). (S103). The emergency event may be output using any physical phenomenon. For example, in S102, the wireless terminal 10 may transmit a signal having a predetermined signal sequence indicating an emergency event as a radio wave. A predetermined signal sequence indicating an emergency event may be generated using a predetermined sequence such as a Zadoff Chu sequence or a CAZAC sequence. When transmitting a signal having a predetermined signal sequence indicating an emergency event (which may also be called an emergency event signal) as a radio wave, the wireless terminal 10 outputs an emergency event using a wireless communication circuit and an antenna used in V2X communication. It may be configured to do so.
[0052]
　In S102, the wireless terminal 10 may transmit a signal having a predetermined signal sequence indicating an emergency event as a sound wave. When transmitting a signal having a predetermined signal sequence indicating an emergency event (which may also be referred to as an emergency event signal) as a sound wave, the wireless terminal 10 uses a speaker, a horn (also referred to as a horn or a horn), a siren, or a megaphone. It may be configured to output an emergency event by using or the like. The emergency event signal output as a sound wave may be, for example, a siren sound sounded by an emergency vehicle during an emergency run, or a horn sound sounded by a moving body such as a vehicle or a ship in an emergency.
[0053]
　The wireless terminal 10 that outputs the emergency event in S102 executes V2X communication using the selected wireless resource (S104). When the wireless terminal 10 outputs an emergency event in S102, the wireless resource belonging to the first reserved area is released from the resource pool of the other wireless terminal 10, so that the wireless resource belonging to the first reserved area is used immediately. It becomes possible to send to.
[0054]
　On the other hand, when it is determined in S101 that the mode is not in emergency mode (NO in S101), the wireless terminal 10 determines whether or not an emergency event has been detected (S105). The wireless terminal 10 may be configured to execute a determination process (S105) as to whether or not an emergency event has been detected when a predetermined flag stored in the memory is set to off.
[0055]
　In S105, the wireless terminal 10 may detect an emergency event output as a sound wave based on an input signal from an acoustic signal input device such as a microphone. For example, the wireless terminal 10 converts an input signal from an acoustic signal input device into a frequency component by a fast Fourier transform (FFT (Fast Fourier Transform)) device, and stores it in a memory in advance as a predetermined reference. It may be determined that an emergency event has been detected when the degree of coincidence between the frequency component obtained from the input signal and the reference frequency component is equal to or greater than the threshold value as compared with the frequency component. On the other hand, the wireless terminal 10 may determine that the emergency event is not detected when the degree of coincidence between the frequency component obtained from the input signal and the reference frequency component is less than the threshold value.
[0056]
　In S105, the wireless terminal 10 may detect an emergency event output as a radio wave based on the signal acquired by the antenna and the wireless communication circuit used in the V2X communication. For example, the wireless terminal 10 monitors the radio resources of the side link channel for V2X communication (may be referred to as sensing), and has a signal having a predetermined signal sequence indicating an emergency event (referred to as an emergency event signal). If) is detected, it may be determined that an emergency event has been detected. On the other hand, the wireless terminal 10 may determine that the emergency event is not detected when the signal of the predetermined signal sequence indicating the emergency event is not detected in the radio resource of the side link channel for V2X communication. In the side link channel for V2X communication, the radio resource to which the emergency event signal is mapped may be fixedly allocated. For example, a predetermined subframe in the second time window of the side link channel may be reserved as a radio resource to which the emergency event signal is mapped. The radio resource reserved for the emergency event signal may be referred to, for example, as a second reserved area.
[0057]
　FIG. 8 is a diagram showing an example of a first reserved area and a second reserved area in the second time window of the side link channel according to the first embodiment. As illustrated in Figure 8, in the second time window side link channel (Selection Window), the first reserved area (1 st and Reserved Area), a second reserved area (2 nd and are arranged Reserved Area) .. Since the first reserved area in FIG. 8 is the same as the first reserved area illustrated in FIG. 6, the description thereof will be omitted. The second reserved area in FIG. 8 is arranged in the first subframe from the beginning of the second time window in the time axis direction. The second reserved region illustrated in FIG. 8 has the same size as the side link channel in the frequency axis direction, which is an example. For example, the second reserved region may be smaller than the side link channel in the frequency axis direction, or may be arranged in any of a plurality of subchannels included in the side link channel.
[0058]
　As illustrated in FIG. 8, the second reserved area reserved for the emergency event signal is arranged in the first subframe of the second time window, so that the wireless terminal 10 can perform an emergency event at a relatively early timing. Can be detected. In other words, the wireless terminal 10 may monitor only the wireless resource belonging to the second reserved area in the determination process of S105. The emergency event signal does not have to be mapped to all the radio resources belonging to the second reserved area. In other words, the emergency event signal may be mapped to a part of the radio resource belonging to the second reserved area. For example, the emergency event signal may be mapped to a part of the radio resources belonging to the second reserved area at the beginning in the time axis direction (for example, may be referred to as a symbol, a slot, or the like). As a result, the wireless terminal 10 can detect an emergency event at an earlier timing.
[0059]
　In FIG. 8, a gap for one subframe is provided between the second reserved area and the first reserved area. The wireless terminal 10 may execute the process of detecting the emergency event signal from the radio resource belonging to the second reserved area within the gap period between the second reserved area and the first reserved area. The time length of the gap period may be longer than one subframe or may be zero. When the gap period is 0, the wireless terminal 10 may execute the emergency event signal detection process within the period of the second reserved area. In other words, the second reserved area and the first reserved area may be adjacent to each other in the time axis direction.
[0060]
　Returning to the description of FIG. When it is determined in S105 that an emergency event has been detected (YES in S105), the wireless terminal 10 releases the wireless resource belonging to the first reserved area from the resource pool for V2X communication (S106). As a result, the radio resource belonging to the first reserved area is excluded from the selection target of V2X communication. In other words, even if the wireless terminal 10 that is not in the emergency mode has already selected the wireless resource belonging to the first reserved area as the wireless resource for V2X communication, when an emergency event is detected, the wireless resource is selected. It may be controlled not to be used for V2X communication.
[0061]
　The wireless terminal 10 determines whether or not a wireless resource can be selected from the resource pool after being released by S106 (S107). In S107, the wireless terminal 10 determines that the wireless resource can be selected when the wireless resource belongs to an area other than the first reserved area and the wireless resource that can be used for V2X communication exists in the resource pool. It may be (YES in S107). On the other hand, in S107, the wireless terminal 10 may determine that the wireless resource cannot be selected when the wireless resource that can be used for V2X communication does not exist in the resource pool (NO in S107).
[0062]
　In S107, when it is determined that the wireless resource can be selected from the resource pool released by S106 (YES in S107), the wireless terminal 10 selects the wireless resource from the resource pool (S108) and is selected. V2X communication is performed using wireless resources (S104). As a result, when an emergency event is detected, the wireless resource belonging to the first reserved area is excluded from the selection target of the V2X communication in the wireless terminal 10 that is not in the emergency mode, and the wireless resource belonging to the area other than the first reserved area is V2X. Used for communication.
[0063]
　On the other hand, in S107, when it is determined that the wireless resource cannot be selected from the resource pool after the release by S106 (NO in S107), the wireless terminal 10 stops the V2X communication in the second time window, and next time. The processing after S101 or S105 may be executed with the timing when the second time window of No. 1 arrives as an opportunity.
[0064]
　Further, when it is determined in S105 that the emergency event is not detected (NO in S105), the wireless terminal 10 does not execute the resource pool release process (S106) and selects a wireless resource from the resource pool (S108). , V2X communication is performed using the selected radio resource (S104). As a result, when an emergency event is not detected, the wireless resource belonging to the first reserved area can be selected for V2X communication in the wireless terminal 10 that is not in the emergency mode.
[0065]
　The above is an example of the processing flow in the wireless terminal 10 according to the first embodiment. The processing flow illustrated in FIG. 7 is an example, and the order of each step may be changed as appropriate. An example of the processing flow illustrated in FIG. 7 is an example of a part of the processing in the wireless terminal 10 according to the first embodiment. The wireless terminal 10 may execute other processing in addition to the processing flow illustrated in FIG. 7.
[0066]
　According to one aspect of Example 1 disclosed above, a second wireless terminal (which may also be referred to as an emergency mode wireless terminal) contains urgent information in a packet to be transmitted by V2X communication, which causes an emergency event. By outputting, the wireless resource belonging to the first reserved area is released from the resource pool of another wireless terminal (which may also be called a wireless terminal that is not in emergency mode). Therefore, the wireless resource belonging to the first reserved area is used. V2X communication can be performed. Thereby, the delay in V2X communication can be effectively suppressed.
[0067]
　According to another aspect of the first embodiment disclosed above, when there is no second wireless terminal in which the packet to be transmitted by V2X communication contains urgent information, the wireless terminal that is not in the emergency mode is reserved for the first time. Radio resources belonging to the area may be used. As a result, it is possible to suppress a decrease in utilization efficiency of wireless resources for V2X communication, and it is possible to effectively suppress a delay in V2X communication.
[0068]
　 In the second embodiment, the first reserved area has a plurality of first divided areas, and the second reserved area has a plurality of second divided areas. Then, each of the plurality of first divided regions has a one-to-one correspondence with each of the plurality of second divided regions. According to one aspect of the second embodiment, when the wireless terminal 10 is in the emergency mode, the wireless terminal 10 uses any one of the plurality of second division regions to signal a predetermined signal sequence indicating an emergency event (also referred to as an emergency event signal). Can be configured to output). According to another aspect of the second embodiment, when the wireless terminal 10 is not in the emergency mode, the radio terminal 10 may be referred to as a signal having a predetermined signal sequence indicating an emergency event (also referred to as an emergency event signal) for each of the plurality of second division regions. ) Is detected, and the radio resource belonging to the first division area corresponding to the second division area in which the emergency event signal is detected may be excluded from the selection target of V2X communication.
[0069]
　FIG. 9 is a diagram showing an example of a first reserved area and a second reserved area in the second time window of the side link channel according to the second embodiment. The first reserved area (1 st Reserved Area) in FIG. 9 has four first divided regions (RA-1, RA-2, RA-3, RA-4) in the frequency axis direction. Similarly, the second reserved area in FIG 9 (2 nd Reserved Area) is in the frequency axis direction and has a four second divided area (RS-1, RS-2 , RS-3, RS-4). Each of the four first division regions (RA-1, RA-2, RA-3, RA-4) has four second division regions (RS-1, RS-2, RS-3, RS-4). Is associated with each of. In the example of FIG. 9, the first divided region (RA-1) and the second divided region (RS-1) belong to the same subchannel (F10-A) and have a corresponding relationship. In other words, the first division area (RA-1) is associated with the second division area (RS-1). Similarly, the first division region (RA-2) corresponds to the second division region (RS-2), the first division region (RA-3) corresponds to the second division region (RS-3), and the first The 1 division region (RA-4) corresponds to the 2nd division region (RS-4). In other words, the first division region (RA-2) and the second division region (RS-2) belong to the same subchannel (F10-B), and the first division region (RA-3) and the second division region (RA-3) and the second division region. (RS-3) belongs to the same subchannel (F10-C), and the first division region (RA-4) and the second division region (RS-4) belong to the same subchannel (F10-D).
[0070]
　As illustrated in FIG. 9, the emergency event signal can be mapped in any of the second division regions (RS-1 to RS-4). In the example of FIG. 9, an emergency event signal is sent to the second division region (RS-1) belonging to the subchannel (F10-A) and the second division region (RS-2) belonging to the subchannel (F10-B). Is mapped. In other words, in the example of FIG. 9, the second division region (RS-3) belonging to the subchannel (F10-C) and the second division region (RS-4) belonging to the subchannel (F10-D) are defined. , Emergency event signals are not mapped.
[0071]
　As illustrated in FIG. 9, the radio resource is released from the resource pool only in the first division region corresponding to the second division region to which the emergency event signal is mapped. In the example of FIG. 9, wireless from the resource pool in the first division region (RA-1, RA-2) corresponding to each of the second division regions (RS-1, RS-2) to which the emergency event signal is mapped. Resources are released. In other words, in the example of FIG. 9, in the first division region (RA-3, RA-4) corresponding to each of the second division regions (RS-3, RS-4) to which the emergency event signal is not mapped. , Radio resources are not released from the resource pool.
[0072]
　FIG. 10 is a diagram showing an example of a processing flow in the wireless terminal according to the second embodiment. An example of the processing flow shown in FIG. 10 may be executed, for example, at the timing when a packet to be transmitted by V2X communication is generated. Further, an example of the processing flow shown in FIG. 10 is executed when, for example, a packet to be transmitted by V2X communication exists in the buffer at the timing when the start point of the second time window (which may also be referred to as Selection Window) arrives. May be done. These are examples of the triggers for executing the processing flow shown in FIG. 10, and may be executed at other timings. In FIG. 10, the same reference numerals are given to the parts similar to the processing flow in the wireless terminal according to the first embodiment illustrated in FIG. 7.
[0073]
　When the wireless terminal 10 determines that the mode is an emergency mode (YES in S101), the wireless terminal 10 outputs an emergency event according to the priority (S102A). In S102A, the wireless terminal 10 may determine the priority according to, for example, the length of a packet containing urgent information (which may be referred to as packet length or data length). For example, the wireless terminal 10 may be determined so that the larger the packet length, the higher the priority. Alternatively, the wireless terminal 10 may determine the priority based on the priority information set in the packet. Alternatively, the wireless terminal 10 may determine the priority based on the priority information stored in advance in the memory. The range of priority may be defined so as to correspond to the number of the first division area or the second division area. For example, when there are four second division regions, the priority range may be 0 to 3. In other words, the maximum value of priority may be defined to correspond to the number of first division regions or second division regions. For example, when there are four second division regions, the maximum priority value may be the value "3" obtained by subtracting "1" from the "number of second division regions".
[0074]
　In S102A, the wireless terminal 10 may select the second division region to which the emergency event signal is mapped according to the priority value. For example, when the priority is "0", the wireless terminal 10 may map the emergency event signal to one second division region (RS-1). For example, when the priority is "1", the wireless terminal 10 may map the emergency event signal to the two second division regions (RS-1, RS-2). For example, when the priority is "2", the wireless terminal 10 may map the emergency event signal to the three second division regions (RS-1, RS-2, RS-3). For example, when the priority is "3", the wireless terminal 10 may map the emergency event signal to the four second division regions (RS-1, RS-2, RS-3, RS-4). .. In this way, the number of selected second division regions may be increased or decreased according to the priority value. Alternatively, the wireless terminal 10 may change the position of the selected second division region according to the priority value, and the number of the selected second division regions may be fixed. For example, when the priority is "0", only the second division area (RS-1) is selected, and when the priority is "1", only the second division area (RS-2) is selected and the priority is given. When is "2", only the second division area (RS-3) may be selected, and when the priority is "3", only the second division area (RS-4) may be selected.
[0075]
　The wireless terminal 10 selects a wireless resource to be used for V2X communication from the first divided area according to the priority (S103A). In S103A, the wireless terminal 10 may select, for example, the first division area corresponding to the second division area selected according to the priority by S102A. In the example of FIG. 9, two second division regions (RS-1, RS-2) are selected according to the priority, and the wireless terminal 10 uses these selected second division regions (RS-1). , RS-2), the radio resource for V2X communication may be selected from the radio resources belonging to the first division region (RA-1, RA-2). In other words, the wireless terminal 10 is a radio belonging to the first division region (RA-3, RA-4) corresponding to the second division region (RS-3, RS-4) that is not selected according to the priority. From the resources, it is not necessary to select the wireless resource for V2X communication.
[0076]
　The wireless terminal 10 performs V2X communication using the selected wireless resource (S104). As a result, the wireless terminal 10 can perform V2X communication using any of the wireless resources belonging to the range of the first division region adjusted according to the high priority.
[0077]
　On the other hand, when it is determined that the wireless terminal 10 is not in the emergency mode (NO in S101), the wireless terminal 10 determines whether an emergency event is detected in any of the plurality of second division regions (S105A). The wireless terminal 10 may be configured to execute a determination process (S105A) for determining whether an emergency event has been detected when a predetermined flag stored in the memory is set to off.
[0078]
　In S105A, the wireless terminal 10 may monitor each of the plurality of second division regions and determine whether or not an emergency event signal is detected in each of the plurality of second division regions.
[0079]
　When it is determined that an emergency event is detected in any of the plurality of second division areas (YES in S105A), the wireless terminal 10 releases the radio resource belonging to the first division area corresponding to the emergency event from the resource pool. (S106A). In S106A, for example, the radio terminal 10 may release the radio resource belonging to the first division area corresponding to the second division area in which the emergency event signal is detected by S105A from the resource pool for V2X communication.
[0080]
　According to the example of FIG. 9, the wireless terminal 10 detects an emergency event signal in the two second division regions (RS-1, RS-2), and corresponds to the second division region (RS-1). The radio resource belonging to the 1 division area (RA-1) and the radio resource belonging to the 1st division area (RA-2) corresponding to the 2nd division area (RS-2) are released from the resource pool for V2X communication. Can be done.
[0081]
　The wireless terminal 10 determines whether or not a wireless resource can be selected from the resource pool after being released by S106A (S107). In S107, when it is determined that the wireless resource can be selected from the resource pool released by S106 (YES in S107), the wireless terminal 10 selects the wireless resource from the resource pool (S108) and is selected. V2X communication is performed using wireless resources (S104). As a result, when an emergency event is detected, the wireless resource belonging to the first division area corresponding to the second division area in which the emergency event is detected is excluded from the selection target of V2X communication in the wireless terminal 10 that is not in the emergency mode. Radio resources belonging to an area other than the first division area can be used for V2X communication.
[0082]
　On the other hand, in S107, when it is determined that the wireless resource cannot be selected from the resource pool after the release by S106A (NO in S107), the wireless terminal 10 stops the V2X communication in the second time window, and next time. The processing after S101 or S105A may be executed at the timing when the second time window of the above is reached.
[0083]
　Further, when it is determined in S105A that an emergency event is not detected (NO in S105A), the wireless terminal 10 does not release the resource pool by S106A, selects a wireless resource from the resource pool (S108), and selects it. V2X communication is performed using the obtained radio resource (S104). As a result, when an emergency event is not detected, the wireless resource belonging to the first division region can be selected for V2X communication in the wireless terminal 10 that is not in the emergency mode. Even if the emergency event is not detected, the radio resource belonging to the second division area may be excluded from the selection target of V2X communication.
[0084]
　The above is an example of the processing flow in the wireless terminal 10 according to the second embodiment. The processing flow illustrated in FIG. 10 is an example, and the order of each step may be changed as appropriate. An example of the processing flow illustrated in FIG. 10 is an example of a part of the processing in the wireless terminal 10 according to the second embodiment. The wireless terminal 10 may execute other processing in addition to the processing flow illustrated in FIG.
[0085]
　According to one aspect of the second embodiment disclosed above, the first reserved area and the second reserved area are subdivided into a plurality of first divided areas and a plurality of second divided areas, respectively. Then, the second wireless terminal (which may also be referred to as an emergency mode wireless terminal or a second wireless terminal) in which the packet to be transmitted by V2X communication contains urgent information outputs an emergency event according to the priority. Then, the wireless resources belonging to the first divided area corresponding to the emergency event are released from the resource pool of the other wireless terminal (the wireless terminal that is not in the emergency mode, which may also be called the first wireless terminal), so that the first divided area is released. V2X communication can be performed using the radio resources belonging to. In other words, in the wireless communication system 1 according to the second embodiment, the amount of wireless resources released in the first wireless terminal is controlled according to the priority in the second wireless terminal. As a result, it is possible to effectively suppress the delay in V2X communication by the wireless terminal in the emergency mode, and suppress the decrease in the utilization efficiency of the wireless resource for V2X communication. As a result, by suppressing the decrease in the utilization efficiency of the wireless resource for V2X communication, it is possible to effectively suppress the delay in V2X communication by the wireless terminal which is not in the emergency mode.
[0086]
　According to another aspect of the second embodiment disclosed above, when there is no second wireless terminal in which the packet to be transmitted by V2X communication contains urgent information, the wireless terminals that are not in the emergency mode may have a plurality of first radio terminals. Radio resources belonging to the first reserved area including the one-divided area can be used. As a result, it is possible to suppress a decrease in utilization efficiency of wireless resources for V2X communication, and it is possible to effectively suppress a delay in V2X communication.
[0087]
　 In the third embodiment, the time range to which the emergency event is applied is extended in the side link channel for V2X communication. According to one aspect of the third embodiment, when the wireless terminal 10 detects an emergency event, the wireless terminal 10 uses a wireless resource belonging to the first reserved area of ​​the second time window at the timing when the emergency event is detected as a resource pool for V2X communication. The radio resource belonging to the first reserved area in the plurality of second time windows from the detection of the emergency event to the elapse of a predetermined time is released from the resource pool for V2X communication. Can be done. In other words, in one or more second time windows included in the time period from the detection of the emergency event to the elapse of the predetermined time, the radio resources belonging to the first reserved area are continuously excluded from the selection target. To. According to another aspect of the third embodiment, when the wireless terminal 10 is in the emergency mode, the wireless terminal 10 uses the wireless resource belonging to the first reserved area of ​​the second time window at the timing when the emergency event is output to perform V2X communication. Can be configured to do. Further, according to another aspect of the third embodiment, V2X communication is performed by using the radio resources belonging to the first reserved area in the plurality of second time windows from the timing when the emergency event is output to the elapse of a predetermined time. May be configured to do.
[0088]
　FIG. 11 is a diagram showing an example of a time range in which an emergency event is applied in the side link channel according to the third embodiment. In FIG. 11, five second time windows (W-10, W-20, W-30, W-40, W-50) in the side link channel for V2X communication are illustrated, and the time is from the left end to the right. Suppose that progresses.
[0089]
　In FIG. 11, no emergency event is output in the second time window (W-10), which is the first from the left end. Therefore, the radio resource belonging to the first reserved area (RA-10) in the second time window (W-10) can be used by a radio terminal (which may also be referred to as a first radio terminal) that is not in the emergency mode. In other words, the radio resource belonging to the first reserved area (RA-10) in the second time window (W-10) may not be used by the radio terminal in emergency mode (which may also be referred to as the second radio terminal). ..
[0090]
　In FIG. 11, the emergency event (RS-20) is output in the second time window (W-20), which is the second from the left end. Therefore, the radio resource belonging to the first reserved area (RA-20) in the second time window (W-20) is released from the resource pool of the radio terminal (which may also be referred to as the first radio terminal) which is not in the emergency mode. .. In other words, the first radio terminal does not use the radio resource belonging to the first reserved area (RA-20) in the second time window (W-20). In other words, the second radio terminal may use the radio resource belonging to the first reserved area (RA-20) in the second time window (W-20).
[0091]
　In FIG. 11, no emergency event is output from the third second time window (W-30) and the fourth second time window (W-40) from the left end. However, the emergency event (RS-20) output in the second time window (W-20) is applied to the second time window (W-30) and the second time window (W-40). In other words, in the example of FIG. 11, the second time window (W-30) and the second time window (W-40) are the time periods from the timing when the emergency event is output to the elapse of a predetermined time. This is an example. For example, the first wireless terminal is a second time window (W-30, W-40) included in a predetermined time period from the second time window (W-20) from which the emergency event (RS-20) is output. The radio resources belonging to the first reserved area (RA-30, RA-40) in each are released (excluded) from the resource pool for V2X communication. For example, the second wireless terminal is a second time window (W-30, W-40) included in a predetermined time period from the second time window (W-20) from which the emergency event (RS-20) is output. V2X communication is performed using the radio resources belonging to the first reserved area (RA-30, RA-40) in each.
[0092]
　In FIG. 11, the fifth second time window (W-50) from the left end is the same as the third second time window (W-30) and the fourth second time window (W-40) from the left end. , No emergency event is output. However, the emergency event (RS-20) output in the second time window (W-20) is not applied to the second time window (W-50). In other words, in the example of FIG. 11, the second time window (W-50) is an example of the second time window after the time period from the timing when the emergency event is output to the elapse of a predetermined time. .. The radio resource belonging to the first reserved area (RA-50) in the second time window (W-50) can be used by the first radio terminal. In other words, the radio resource belonging to the first reserved area (RA-50) in the second time window (W-50) may not be used by the second radio terminal.
[0093]
　12A and 12B are diagrams showing an example of a processing flow in the wireless terminal according to the third embodiment. An example of the processing flow shown in FIGS. 12A and 12B may be executed, for example, at the timing when a packet to be transmitted by V2X communication is generated. Further, in an example of the processing flow shown in FIGS. 12A and 12B, for example, a packet to be transmitted by V2X communication exists in the buffer at the timing when the start point of the second time window (which may also be referred to as Selection Window) arrives. May be executed if. These are examples of the triggers for executing the processing flow shown in FIGS. 12A and 12B, and may be executed at other timings. In FIG. 12, the same reference numerals are given to the parts similar to the processing flow in the wireless terminal according to the first embodiment illustrated in FIG. 7.
[0094]
　In the process flow exemplified in FIG. 12A, the wireless terminal 10 may execute each step shown in S101 to S105 in the same manner as in FIG. 7. In FIG. 12A, each step shown in S101 to S105 is the same as the step shown in S101 to S105 in FIG. 7, and therefore detailed description thereof will be omitted. The wireless terminal 10 may execute S103 by omitting the output of the emergency event in S102 until the elapsed time from the output of the emergency event by the previous execution of S102 exceeds the threshold value. In S102, the wireless terminal 10 may measure the elapsed time from outputting the emergency event by a timer. Alternatively, the wireless terminal 10 stores information indicating the time when the emergency event was output in S102 (which may be referred to as an output time) in the memory, and each time S102 is executed, the difference between the current time and the output time. The elapsed time may be obtained by calculating.
[0095]
　When the wireless terminal 10 determines in S105 that an emergency event has been detected (YES in S105), the wireless terminal 10 sets an emergency flag indicating that the emergency event has been detected (S109A). The emergency flag is a flag that can be used to determine whether or not an emergency event has been detected in a time period up to a predetermined time before the execution timing when the processing flow illustrated in FIG. 12A is executed. Is. For example, the wireless terminal 10 may reserve a 1-bit length storage area for the emergency flag in the memory, and set the value "1" in the storage area for the emergency flag in S109A. The value of the emergency flag shall be retained even after the processing flow shown in FIGS. 12A and 12B is completed, unless it is initialized.
[0096]
　In S109A, the wireless terminal 10 may store the time at the time when the emergency event is detected in the memory. Alternatively, the wireless terminal 10 may start the measurement by the timer that counts the elapsed time since the emergency flag is set in S109A.
[0097]
　The wireless terminal 10 releases the wireless resource belonging to the first reserved area from the resource pool for V2X communication (S106). As a result, the radio resource belonging to the first reserved area is excluded from the selection target of V2X communication. In other words, even if the wireless terminal 10 that is not in the emergency mode has already selected the wireless resource belonging to the first reserved area as the wireless resource for V2X communication, when an emergency event is detected, the wireless resource is selected. It may be controlled not to be used for V2X communication.
[0098]
　The wireless terminal 10 determines whether or not a wireless resource can be selected from the resource pool after being released by S106 (S107). In S107, the wireless terminal 10 determines that the wireless resource can be selected when the wireless resource belongs to an area other than the first reserved area and the wireless resource that can be used for V2X communication exists in the resource pool. It may be (YES in S107). On the other hand, in S107, the wireless terminal 10 may determine that the wireless resource cannot be selected when the wireless resource that can be used for V2X communication does not exist in the resource pool (NO in S107).
[0099]
　In S107, when it is determined that the wireless resource can be selected from the resource pool released by S106 (YES in S107), the wireless terminal 10 selects the wireless resource from the resource pool (S108) and is selected. V2X communication is performed using wireless resources (S104). As a result, when an emergency event is detected, the wireless resource belonging to the first reserved area is excluded from the selection target of the V2X communication in the wireless terminal 10 that is not in the emergency mode, and the wireless resource belonging to the area other than the first reserved area is V2X. Used for communication.
[0100]
　On the other hand, in S107, when it is determined that the wireless resource cannot be selected from the resource pool after the release by S106 (NO in S107), the wireless terminal 10 stops the V2X communication in the second time window, and next time. The processing after S101 or S105 may be executed with the timing when the second time window of No. 1 arrives as an opportunity.
[0101]
　Further, when it is determined in S105 that the emergency event is not detected (NO in S105), the wireless terminal 10 determines whether or not the emergency flag indicating that the emergency event has been detected is set (S110A). Note that in FIG. 12A, the reference numeral “A” shown as the transition destination in the case of NO in S105 indicates the reference numeral “A” shown in FIG. 12B.
[0102]
　In S110A, for example, the wireless terminal 10 refers to the storage area for the emergency flag reserved in the memory, and when the value "1" is stored in the storage area for the emergency flag, the emergency event is detected. It may be determined that the emergency flag indicating is set (YES in S110A). On the other hand, in S110A, when the value "0" is stored in the storage area for the emergency flag reserved in the memory, the wireless terminal 10 has not set the emergency flag indicating that the emergency event has been detected. It may be determined (NO in S110A).
[0103]
　When the wireless terminal 10 determines that the emergency flag is set (YES in S110A), the wireless terminal 10 determines whether the elapsed time since the emergency flag is set is equal to or greater than the threshold value (S111A). In S111A, the wireless terminal 10 acquires information indicating the time (which may be referred to as the detection time) at the time when the emergency event is detected by referring to the memory, for example, and sets the current time and the detection time. The elapsed time may be obtained by calculating the difference. Alternatively, in S111A, the wireless terminal 10 may acquire the elapsed time by, for example, acquiring the timer value measured by the timer that counts the elapsed time since the emergency flag is set.
[0104]
　When the elapsed time from the setting of the emergency flag is equal to or greater than the threshold value (YES in S111A), the wireless terminal 10 initializes the emergency flag (S112A). In S112A, the wireless terminal 10 may initialize the emergency flag by setting the value "0" in the storage area for the emergency flag reserved in the memory, for example.
[0105]
　Further, when the elapsed time since the emergency flag is set is equal to or longer than the threshold value (YES in S111A), the wireless terminal 10 selects a wireless resource from the resource pool (S108), and uses the selected wireless resource for V2X. Communicate (S104). As a result, when a predetermined time elapses after the emergency event is detected, the wireless resource belonging to the first reserved area is also included in the selection target of the V2X communication in the wireless terminal 10 which is not in the emergency mode. It should be noted that in FIG. 12B, the reference numeral “B” shown as the transition destination after the determination of YES in S111A indicates the reference numeral “B” shown in FIG. 12A.
[0106]
　On the other hand, in S111A, when it is determined that the elapsed time since the emergency flag is set is less than the threshold value (NO in S111A), the wireless terminal 10 uses the wireless resource belonging to the first reserved area for V2X communication. Release from the resource pool (S106). This extends the time range to which the emergency event applies. In other words, the radio resource belonging to the first reserved area is excluded from the selection target of V2X communication. In other words, even if the wireless terminal 10 that is not in the emergency mode has already selected the wireless resource belonging to the first reserved area as the wireless resource for V2X communication, if an emergency event is detected, the wireless resource is said to be the wireless resource. May be controlled not to be used for V2X communication. It should be noted that in FIG. 12B, the reference numeral “C” shown as the transition destination after the determination of NO in S111A indicates the reference numeral “C” shown in FIG. 12A.
[0107]
　The wireless terminal 10 determines whether or not a wireless resource can be selected from the resource pool after being released by S106 (S107). In S107, when it is determined that the wireless resource can be selected from the resource pool released by S106 (YES in S107), the wireless terminal 10 selects the wireless resource from the resource pool (S108) and is selected. V2X communication is performed using wireless resources (S104). As a result, in the wireless terminal 10 that is not in the emergency mode, the wireless resource belonging to the first reserved area is excluded from the selection target of the V2X communication, and the wireless resource belonging to the area other than the first reserved area is used for the V2X communication.
[0108]
　On the other hand, in S107, when it is determined that the wireless resource cannot be selected from the resource pool after the release by S106 (NO in S107), the wireless terminal 10 stops the V2X communication in the second time window, and next time. The processing after S101 or S105 may be executed with the timing when the second time window of No. 1 arrives as an opportunity.
[0109]
　Further, when it is determined in S110A that the emergency flag indicating that an emergency event has been detected is not set (NO in S110A), the wireless terminal 10 selects a wireless resource from the resource pool (S108) and selects it. V2X communication is performed using the radio resources (S104). As a result, in the wireless terminal 10 that is not in the emergency mode, the wireless resource belonging to the first reserved area is also included in the selection target of the V2X communication. It should be noted that in FIG. 12B, the reference numeral “B” shown as the transition destination after the determination of NO in S110A indicates the reference numeral “B” shown in FIG. 12A.
[0110]
　The above is an example of the processing flow in the wireless terminal 10 according to the third embodiment. The processing flow illustrated in FIGS. 12A and 12B is an example, and the order of each step may be changed as appropriate. An example of the processing flow exemplified in FIGS. 12A and 12B is an example of a part of the processing in the wireless terminal 10 according to the third embodiment. The wireless terminal 10 may execute other processes in addition to the process flow illustrated in FIGS. 12A and 12B.
[0111]
　According to one aspect of the third embodiment disclosed above, when an emergency event is detected, the wireless terminal 10 V2X the radio resource belonging to the first reserved area of ​​the second time window at the timing when the emergency event is detected. Release from the resource pool for communication. Further, according to one aspect of the third embodiment, the wireless terminal 10 communicates V2X communication of wireless resources belonging to the first reserved area in a plurality of second time windows from the detection of an emergency event to the elapse of a predetermined time. Release (exclude) from the resource pool for. As a result, the wireless terminal that is not in the emergency mode (which may also be referred to as the first wireless terminal) executes the emergency event detection process in a plurality of second time windows from the detection of the emergency event to the elapse of a predetermined time. It does not have to be. As a result, the first wireless terminal can save the power that can be consumed when the emergency event detection process is executed. As a result, the first wireless terminal can extend the drive time by the battery while effectively suppressing the delay in the V2X communication, and can execute the V2X communication more effectively.
[0112]
　According to another aspect of the third embodiment disclosed above, when the wireless terminal in the emergency mode (which may also be referred to as the second wireless terminal) is in the emergency mode, the second at the timing when the emergency event is output. The radio resource belonging to the first reserved area of ​​the time window can be used for V2X communication. Further, according to another aspect of the third embodiment, the second radio terminal is urgent in a plurality of second time windows included in the time period from when the emergency event is output until the elapsed time becomes equal to or more than the threshold value. The radio resource belonging to the first reserved area can be used for V2X communication while omitting the output of the event. As a result, the second wireless terminal is consumed when the output processing of the emergency event is executed in the plurality of second time windows included in the time period from the output of the emergency event to the elapsed time exceeding the threshold value. The power that can be generated can be preserved. As a result, the second wireless terminal can extend the drive time by the battery while effectively suppressing the delay in the V2X communication, and can execute the V2X communication more effectively.
[0113]
　According to still another aspect of Example 3 disclosed above, if the packet to be transmitted by V2X communication does not have a second radio terminal containing urgent information, the first radio terminal that is not in emergency mode will be: Radio resources belonging to the first reserved area may be used. As a result, it is possible to suppress a decrease in utilization efficiency of wireless resources for V2X communication, and it is possible to effectively suppress a delay in V2X communication.
[0114]
　 Finally, the hardware configuration of the wireless terminal 10 and the wireless base station 20 used in each of the above disclosed embodiments will be briefly described.
[0115]
　FIG. 13 is a diagram showing an example of a hardware configuration of a wireless terminal (UE) 10 and a wireless base station (eNB / gNB) 20 in the wireless communication system 1. It should be noted that the wireless terminal 10-1 and the wireless terminal 10-2 shown in FIG. 13 can be the above-mentioned first wireless terminal and can also be the second wireless terminal.
[0116]
　The UE 10 (that is, UE10-1 and UE10-2) in FIG. 13 includes a wireless communication circuit 101 (may be referred to as a wireless communication unit, a second wireless communication unit, and a second wireless communication circuit), and a processing circuit 102 (processing). It has a unit, a second processing unit, a second processing circuit), a memory 103, and the like. Note that the UE 10 in FIG. 13 is not shown with respect to a part of the configuration such as an antenna. Further, the UE 10 may include a display device such as a liquid crystal display, an input device such as a touch panel, and a battery such as a lithium-ion rechargeable battery. Further, when the UE 10 in FIG. 13 is configured to output an emergency event signal as a sound wave, it may be provided with a speaker, a sound alarm (which may also be referred to as a horn or a horn), a siren, a megaphone, or the like.
[0117]
　The wireless communication circuit 101 receives a baseband signal (which may be referred to as a wireless signal or a digital wireless signal) from the processing circuit 102, and receives a radio signal (second radio) having a predetermined output level from the baseband signal. It is configured to generate a signal (which may also be referred to as an analog radio signal) and radiate the radio signal into space via an antenna. As a result, the UE 10 can transmit a radio signal to the radio base station 20 or another UE 10. For example, the UE 10-1 may transmit a V2X communication signal to the UE 10-2 by the wireless communication circuit 101 of the UE 10-1. Similarly, the UE 10-2 can transmit a V2X communication signal to the UE 10-1 by the wireless communication circuit 101 of the UE 10-2. Further, the wireless communication circuit 101 is configured to receive the wireless signal input from the antenna, convert the wireless signal into a baseband signal, and supply the baseband signal to the processing circuit 102. As a result, the UE 10 can receive a radio signal from the radio base station 20 or another UE 10. For example, the UE 10-1 may receive a signal of V2X communication from the UE 10-2 by the wireless communication circuit 101 of the UE 10-1. Similarly, the UE 10-2 can receive the signal of V2X communication from the UE 10-1 by the wireless communication circuit 101 of the UE 10-2. As described above, the wireless communication circuit 101 is configured to be capable of transmitting and receiving wireless signals, and has a function of performing wireless communication with the wireless base station 20 or another UE 10. For example, the wireless terminal 10 is a wireless communication circuit 101 shown in FIG. 13, which is a wireless communication circuit 101 for wireless communication with a wireless base station 20 and a wireless communication circuit 101 for V2X communication with another wireless terminal 10. And may be implemented.
[0118]
　The wireless communication circuit 101 may be communicably connected to the processing circuit 102 via a transmission circuit mounted inside the UE 10. Examples of such a transmission circuit include a transmission circuit conforming to standards such as M-PHY and Dig-RF.
[0119]
　The processing circuit 102 (which may be referred to as a processor circuit or an arithmetic circuit) is a circuit configured to perform baseband signal processing. The processing circuit 102 generates a baseband signal (which may be referred to as a wireless signal or a digital wireless signal) based on the wireless communication protocol stack in the wireless communication system 1, and outputs the baseband signal to the wireless communication circuit 101. It is composed of. For example, as the wireless communication protocol, LTE or 5G wireless communication protocol may be used. Further, for example, as the wireless communication protocol, a wireless communication protocol for V2X communication may be used. Further, the processing circuit 102 is configured to perform reception processing such as demodulation / decoding on the baseband signal input from the wireless communication circuit 101 based on the wireless communication protocol stack in the wireless communication system 1. In other words, in the uplink, the processing circuit 102 transmits the first data addressed to the radio base station 20 or another UE 10 from the upper layer according to the procedure of the radio communication protocol stack in which the radio communication function is divided into a plurality of layers. It has an aspect as a circuit for causing the wireless communication circuit 101 to transmit a wireless signal based on at least a part of the second data obtained by sequentially processing the lower layers. Further, the processing circuit 102 is a circuit that sequentially processes the wireless signal received via the wireless communication circuit 101 from the lower layer to the upper layer according to the procedure of the wireless communication protocol stack in which the wireless communication function is divided into a plurality of layers. Has an aspect as. Here, receiving the input of the baseband signal from the wireless communication circuit 101 via the transmission circuit has an aspect of receiving the wireless signal from the wireless base station 20 or another UE 10 via the wireless communication circuit 101. Further, outputting the baseband signal to the wireless communication circuit 101 via the transmission circuit has an aspect of transmitting the radio signal to the wireless base station 20 or another UE 10 via the wireless communication circuit 101.
[0120]
　Even if the processing circuit 102 is an arithmetic unit that realizes the operation of the UE 10 (which may also be referred to as a wireless terminal) according to each of the above-described embodiments by reading and executing a program stored in the memory 103, for example. Good. In other words, the processing circuit 102 is a subject (for example, an operation that executes a processing flow in the operation of the wireless terminal 10 according to each of the above-described embodiments (for example, the operation shown in FIGS. 7, 10, 12A, and 12B). It has an aspect as (which can also be called an arithmetic unit). Examples of the processing circuit 102 include a CPU (Central Processing Unit), an MPU (Micro Processing Unit), a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), and a combination thereof. The processing circuit 102 may be a multi-core processor including two or more cores. Further, the processing circuit 102 may mount two or more processing circuits 102 according to each layer in the wireless communication protocol stack of the wireless communication system 1. Further, for example, the wireless terminal 10 includes a processing circuit 102 for wireless communication with the wireless base station 20 and a processing circuit 102 for V2X communication with another wireless terminal 10 as the processing circuit 102 shown in FIG. It may be implemented.
[0121]
　The processing circuit 102 may be referred to as a C-CPU. In addition to the processing circuit 102, the UE 10 may implement a processor circuit that can also be called an A-CPU that executes an application. The processing circuit 102 may be mounted on one chip together with a processor circuit which may also be referred to as an A-CPU, or may be mounted as a chip different from the A-CPU. The processing circuit 102 may have an aspect as a control unit having a function of controlling the operation of the UE 10. Further, the processing circuit 102 sends a first control message regarding the reconstruction of the wireless connection between the wireless base station 20 and the wireless terminal 10 from the wireless base station 20 to the wireless communication circuit 101 (may be referred to as a wireless communication unit). It may have an aspect as a processing unit configured to receive by.
[0122]
　The memory 103 is a circuit configured to store and hold data and programs related to baseband signal processing executed by the processing circuit 102. The memory 103 includes at least a non-volatile storage device and / or a volatile storage device. For example, RAM (Random Access Memory), ROM (Read Only Memory), SSD (Solid State Drive), HDD (Hard Disk Drive) and the like can be mentioned. In FIG. 13, the memory 103 is a general term for various storage devices such as a main storage device and an auxiliary storage device. As with the processing circuit 102, the memory 103 may be equipped with two or more memories 103 according to each layer in the wireless communication protocol stack of the wireless communication system 1. For example, in the wireless terminal 10, as the memory 103 shown in FIG. 13, a memory 103 for wireless communication with the wireless base station 20 and a memory 103 for V2X communication with another wireless terminal 10 may be mounted. Good.
[0123]
　The wireless base station 20 exemplified in FIG. 13 includes a wireless communication circuit 201 (may be referred to as a wireless communication unit, a first wireless communication unit, or a first wireless communication circuit) and a processing circuit 202 (processing unit, first processing). A unit, which may be referred to as a first processing circuit), a memory 203, and a wired communication circuit 204.
[0124]
　The wireless communication circuit 201 receives a baseband signal from the processing circuit 202 on the downlink, generates a radio signal of a predetermined output level from the baseband signal, and radiates the wireless signal into space via an antenna. It is composed. Further, the wireless communication circuit 201 is configured to receive the wireless signal input from the antenna on the uplink, convert the wireless signal into a baseband signal, and supply the baseband signal to the processing circuit 202. The wireless communication circuit 201 can also be communicatively connected to the processing circuit 202 via a transmission line such as CPRI (Common Public Radio Interface), and is also referred to as RRH (Remote Radio Head) or RRE (Remote Radio Equipment). Can be done. Further, the combination of the wireless communication circuit 201 and the processing circuit 202 is not limited to one-to-one, and one wireless communication circuit 201 may be associated with a plurality of processing circuits 202, or a plurality of wireless communication circuits 201 may be associated with each other. It is also possible to associate with one processing circuit 202, or to associate a plurality of wireless communication circuits 201 with a plurality of processing circuits 202. As described above, the wireless communication circuit 201 has an aspect as a communication unit (which may also be referred to as a transmission / reception unit or a second transmission / reception unit) having a function of performing wireless communication with the UE 10. In other words, the wireless communication circuit 201 may be configured to transmit an RRC message including setting information regarding the configuration of a side link channel for V2X communication to the wireless terminal 10. Such setting information may include, for example, setting information regarding the first reserved area according to the present disclosure. In other words, the RRC message may include setting information regarding the first reserved area according to the present disclosure. The setting information regarding the first reserved area may include, for example, information used by the wireless terminal 10 when specifying the position and size of the first reserved area.
[0125]
　The processing circuit 202 is a circuit configured to perform baseband signal processing. The processing circuit 202 is configured to generate a baseband signal based on the wireless communication protocol stack in the wireless communication system 1 on the downlink and output the baseband signal to the wireless communication circuit 201. Further, the processing circuit 202 is configured to perform reception processing such as demodulation / decoding on the baseband signal input from the wireless communication circuit 201 on the uplink based on the wireless communication protocol stack in the wireless communication system 1. Will be done. In other words, in the downlink, the processing circuit 202 is a side link for V2X communication according to the procedure of a wireless communication protocol stack (for example, LTE or 5G wireless communication protocol stack) in which the wireless communication function is divided into a plurality of layers. It has an aspect as a circuit that sequentially processes an RRC message including setting information regarding a channel configuration from an upper layer to a lower layer and transmits the RRC message via the wireless communication circuit 201. Further, in the uplink, the processing circuit 202 transfers the wireless signal received via the wireless communication circuit 201 from the lower layer to the upper layer according to the procedure of the wireless communication protocol stack in which the wireless communication function is divided into a plurality of layers. It has an aspect as a circuit for sequentially processing. Here, in the uplink, receiving the input of the baseband signal from the wireless communication circuit 201 has an aspect of receiving the wireless signal from the UE 10 via the wireless communication circuit 201. Further, some functions of the processing circuit 202 may be implemented in the wireless communication circuit 201 described above. For example, the wireless communication circuit 201 may include functions related to a physical layer (which may also be referred to as layer 1) in the wireless communication protocol stack. As described above, the arrangement of the implementation related to the processing of the layer (or sublayer) in the wireless communication protocol stack may be redesigned between the wireless communication circuit 201 and the processing circuit 202.
[0126]
　The processing circuit 202 has an aspect as a main body (may be called an arithmetic unit) that executes a processing flow in the radio base station 20 by reading and executing a program stored in the memory 203, for example. .. Examples of the processing circuit 202 include a CPU (Central Processing Unit), an MPU (Micro Processing Unit), a DSP (Digital Signal Processor), and an FPGA (Field Programmable Gate). Array) and so on. The processing circuit 202 may be a multi-core processor including two or more cores. Further, the processing circuit 202 may implement two or more processing circuits 202 according to each layer in the wireless communication protocol stack of the wireless communication system 1. For example, a processing circuit 202 that executes processing as a MAC entity belonging to the MAC layer, a processing circuit 202 that executes processing as an RLC entity belonging to the RLC layer, and a processing circuit 202 that executes processing as a PDCP entity belonging to the PDCP layer. 202 and may be implemented individually. As described above, the processing circuit 202 has an aspect as a control unit having a function of controlling the operation of the radio base station 20 (may be referred to as a second control unit to distinguish it from the control unit of the UE 10). Has. For example, the processing circuit 202 executes a process of transmitting various setting information (for example, the first setting information and the second setting information) to the UE 10. The various setting information may be referred to as a control signal. Further, for example, the processing circuit 202 may be configured to transmit an RRC message including setting information regarding the configuration of a side link channel for V2X communication to the wireless terminal 10. Such setting information may include, for example, setting information regarding the first reserved area according to the present disclosure. In other words, the RRC message may include setting information regarding the first reserved area according to the present disclosure. The setting information regarding the first reserved area may include, for example, information used by the wireless terminal 10 when specifying the position and size of the first reserved area.
[0127]
　The memory 203 is a circuit configured to store and hold data and programs related to baseband signal processing executed by the processing circuit 202. The memory 203 includes at least a non-volatile storage device and / or a volatile storage device. For example, RAM (Random Access Memory), ROM (Read Only Memory), SSD (Solid State Drive), HDD (Hard Disk Drive) and the like can be mentioned. In FIG. 13, the memory 203 is a general term for various storage devices such as a main storage device and an auxiliary storage device. As with the processing circuit 202, the memory 203 may be equipped with two or more memories 203 according to each layer in the wireless communication protocol stack of the wireless communication system 1. For example, a memory 203 used for processing as a MAC entity belonging to the MAC layer, a memory 203 used for processing as an RLC entity belonging to the RLC layer, and a memory 203 used for processing as a PDCP entity belonging to the PDCP layer. , May be implemented individually.
[0128]
　The wired communication circuit 204 converts the packet data into packet data in a format that can be output to another device and transmits the packet data to the other device, or extracts data or the like from the packet data received from the other device to obtain the memory 203 or the processing circuit. Output to 202 or the like. Examples of other devices may include other wireless base stations, MMEs (Mobility Management Entity), SGWs (Serving Gateways), and the like. MME and SGW are also referred to as core nodes, and the logical communication interface used for communication with the core node may also be referred to as S1 interface. The logical communication interface used for communication with other radio base stations may also be referred to as an X2 interface. It should be noted that the names of the various devices mentioned above may be changed in the formulation of LTE or 5G specifications.
[0129]
　The above detailed description will clarify the features and advantages of the present disclosure. It is intended to extend to the features and advantages of the present disclosure as described above, to the extent that the claims do not deviate from their spirit and scope of rights. In addition, anyone with ordinary knowledge in the relevant technical field should be able to easily come up with any improvements or changes. Therefore, there is no intention to limit the scope of disclosure having invention to the above-mentioned ones, and it is possible to rely on appropriate improvements and equivalents included in the scope disclosed herein. For example, each step disclosed herein does not necessarily have to be processed in chronological order in the order described as an example of the processing flow, but within the scope of the claims. , The order of the steps may be changed, or a plurality of steps may be executed in parallel. It should be noted that the circumstances that can occur in the 5G system clarified in the above detailed explanation can be found when the 5G system is examined from one aspect, and when the 5G system is examined from another aspect, other circumstances may occur. Note that it can be found. In other words, the features and advantages of the present invention are not limited to applications that solve the circumstances specified in the above detailed description.
[0130]
　Finally, the configurations of the respective examples and modifications in the present disclosure show an example for embodying the technical idea of ​​the present invention, and the present invention is limited to the configurations of the respective examples and modifications. It is not intended to be, and may be equally applicable to other embodiments within the scope of the claim. For example, it should be noted that the terms in the present disclosure may be renamed in the specification of LTE systems, 5G systems and V2X communications. It should also be noted that one or more alternatives listed for the terms in this disclosure may be synonymous with each other.
Code description
[0131]
1 Wireless communication system
10 Wireless terminal (UE)
101 Wireless communication circuit
102 Processing circuit
103 Memory
20 Wireless base station (eNB / gNB)
201 Wireless communication circuit
202 Processing circuit
203 Memory
204 Wired communication circuit
30 Cell
40 V2X Communication range
The scope of the claims
[Claim 1]
A wireless terminal configured to select a wireless resource for transmitting a signal based on the sensing result, and when a
　predetermined first event is detected, the wireless resource belonging to the first reserved area is selected.
A wireless terminal characterized by being excluded from selection .
[Claim 2]
The wireless terminal according to claim 1
　, wherein when a signal according to a predetermined signal sequence is detected in the second reserved area, it is determined that the first event has been detected
.
[Claim 3]
The wireless terminal according to claim 2,
　wherein the first reserved area has a plurality of first divided areas,
　the second reserved area has a plurality of second divided areas, and the plurality of second reserved areas
　. Each of the one-divided regions has a one-to-one correspondence with each of the plurality of second-divided regions, and
　it is determined whether or not a signal according to the predetermined signal sequence is detected for each of the plurality of second-divided regions. A wireless terminal characterized by
　excluding radio resources belonging to the first division region corresponding to the second division region in which a signal according to the predetermined signal sequence is detected from the selection target
.
[Claim 4]
The wireless terminal according to any one of claims 1 to 3
　, wherein the wireless resource belonging to the first reserved area is selected from the selection target until a predetermined time elapses after the first event is detected.
A wireless terminal characterized by continuing exclusion .
[Claim 5]
The wireless terminal according to claim 1,
　wherein the sensing is sensing for a predetermined wireless resource, and when the first event is not detected, the wireless resource belonging to the first reserved area is included in the selection target.
A wireless terminal characterized by being tolerated .
[Claim 6]
A wireless communication system,
　based on the results of sensing, and a first wireless terminal and a second wireless terminal configured to select a radio resource for transmitting a signal,
　the first wireless terminal When a
　　predetermined first event is detected, the radio resource belonging to the first reserved area is configured to be excluded from the selection target, and
　the second radio terminal is
　　configured to output the first event.
A wireless communication system characterized by the fact that
[Claim 7]
The wireless communication system according to claim 6,
　wherein the first wireless terminal is
　　configured to determine that the first event has been detected when a signal according to a predetermined signal sequence is detected in the second reserved area. The wireless communication system is characterized 　　in that
　the second wireless terminal is
configured to output a signal according to the predetermined signal sequence in the second reserved area
.
[Claim 8]
The wireless communication system according to claim 7,
　wherein the first reserved area has a plurality of first divided areas, and
　the second reserved area has a plurality of second divided areas
　. Each of the first division regions has a one-to-one correspondence with each of the plurality of second division regions, and
　the first radio terminal has the
　　above-mentioned predetermined signal sequence for each of the plurality of second division regions. determine signal is detected,
　　the radio resources that belong to the first divided region signal by said predetermined signal sequence corresponding to the second divided area is detected, excluded from selection,
　it is configured to ,
　the second wireless terminal,
　　in one or more of the second divided region, the output signal with a predetermined signal sequence,
　configured,
a wireless communication system, characterized in that.
[Claim 9]
The wireless communication system according to claim 6,
　wherein the sensing is sensing for a predetermined wireless resource, and
　the first wireless terminal belongs to the first reserved area when the first event is not detected.
A wireless communication system characterized in that wireless resources are allowed to be included in the selection .