TERMINAL AND COMMUNICATION METHOD

Provided is a terminal including: a receiving unit configured to receive reservation information for reserving resources from a plurality of terminals, at least one of the reserved resources being a same resource; a controlling unit configured to identify a first terminal from among the plurality of terminals; and a transmitting unit configured to transmit information related to the same resource to the first terminal, wherein the receiving unit receives data from a second terminal in the same resource.

TECHNICAL FIELD

The present invention relates to a terminal and a communication method in a wireless communication system.

BACKGROUND

In LTE (Long Term Evolution) and LTE successor systems (for example, LTE-A (LTE Advanced), NR (New Radio) (also referred to as 5G)), a D2D (Device to Device) technology in which terminals communicate directly with each other without using base stations is being discussed (for example, Non-Patent Reference 1).

The D2D reduces traffic between the terminals and the base stations and enables communication between the terminals even when the base stations are unable to communicate during a disaster, and the like. Note that, the 3GPP (3rd Generation Partnership Project) refers to D2D as a “sidelink”, but the more generic term D2D is used herein. However, in the description of embodiments below, the sidelink is also used as needed.

The D2D communication is broadly classified into D2D discovery for discovering other terminals capable of communication and D2D communication (also referred to as D2D direct communication, D2D communication, direct communication between terminals, etc.) for communicating directly between terminals. Hereinafter, when D2D communication and D2D discovery are not specifically distinguished, it is simply called D2D. Also, a signal transmitted and received by D2D is called a D2D signal. Various use cases of V2X (Vehicle to Everything) services in NR have been discussed (for example, Non-Patent Reference 2).

RELATED ART

SUMMARY

Technical Problem

Power saving is being discussed as an NR sidelink enhancement. For example, in the resource allocation mode 2, where a terminal autonomously selects resources, the terminal performs partial sensing for sensing a limited number of resources in the sensing window, and based on the results thereof, the terminal selects available resource candidates from the resource selection window.

Here, when the transmission side terminal performs sensing in the resource allocation mode 2, for example, in a case where there is another terminal unviewable from the transmission side terminal, the quality of the resources at the reception side terminal may be significantly different from the quality based on the results of sensing of the resources by the transmission side terminal.

The present invention has been made in view of the foregoing matters, and it is therefore an object of the present invention to improve communication reliability when autonomously selecting resources in direct communication between terminals.

Solution to Problem

According to the disclosed technology, a terminal is provided, including: a receiving unit configured to receive reservation information for reserving resources from a plurality of terminals, at least one of the reserved resources being a same resource, a controlling unit configured to identify a first terminal from among the plurality of terminals, and a transmitting unit configured to transmit information related to the same resource to the first terminal, wherein the receiving unit receives data from a second terminal in the same resource.

Advantageous Effect of the Invention

According to the disclosed technology, it is possible to improve the communication reliability when autonomously selecting resources in direct communication between terminals.

DETAILED DESCRIPTION

Embodiments of the present invention are described below with reference to the drawings. It should be noted that the embodiments described below are examples and the embodiments to which the present invention is applied are not limited to the following embodiments.

Conventional technologies are appropriately used in the operation of the wireless communication system according to an embodiment of the present invention. However, the existing technology is, for example, an existing LTE, but is not limited to the existing LTE. Further, the term “LTE” used herein should have a broad meaning including LTE-Advanced and techniques after LTE-Advanced (for example, NR) or wireless LAN (Local Area Network) unless otherwise specified.

Further, in the embodiments of the present invention, a duplex method may be a TDD (Time Division Duplex) method, an FDD (Frequency Division Duplex) method, or any other method (for example, Flexible Duplex method).

Further, in the embodiments of the present invention, “configuring” a wireless parameter and the like may mean “pre-configuring” a predetermined value or configuring a wireless parameter indicated by a base station10or a terminal20.

FIG.1is a drawing illustrating V2X. In 3GPP, enhancing D2D functions to realize V2X (Vehicle to Everything) or eV2X (enhanced V2X) has been discussed and specifications are being developed. As shown inFIG.1, V2X is a part of ITS (Intelligent Transport Systems) and is a generic name for V2V (Vehicle to Vehicle) referring to a form of communication performed between vehicles; V2I (Vehicle to Infrastructure) referring to a form of communication performed between a vehicle and a road-side unit (RSU) installed on a roadside; V2N (Vehicle to Network) referring to a form of communication performed between a vehicle and an ITS server; and V2P (Vehicle to Pedestrian) referring to a form of communication performed between a vehicle and a mobile terminal that is carried by a pedestrian.

In addition, in 3GPP, V2X using LTE/NR’s cellular communication and communication between terminals has been discussed. V2X using cellular communication may be referred to as cellular V2X. In NR V2X, discussions are ongoing to realize higher capacity, reduced latency, higher reliability, QoS (Quality of Service) control.

It is assumed that discussions with regard to LTE/NR V2X that need not be limited to 3GPP specifications will also be performed in the future. For example, it is assumed that the following will be discussed: how to secure interoperability; how to reduce cost by implementing higher layers; how to use or how to switch a plurality of RATs (Radio Access Technologies); how to handle regulations of each country; how to acquire and deliver data of LTE/NR V2X platform; and how to manage and utilize databases.

In an embodiment of the present invention, a form in which communication apparatuses are mounted on vehicles is mainly assumed. However, an embodiment of the present invention is not limited to such a form. For example, communication apparatuses may be terminals carried by people, may be apparatuses mounted on drones or aircrafts, or may be base stations, RSUs, relay stations (relay nodes), terminals capable of scheduling, and the like.

Note that, SL (Sidelink) may be distinguished from UL (Uplink) or DL (Downlink) based on any one of, or any combination of the following 1) to 4). In addition, SL may have a different name.1) Resource arrangement in the time domain2) Resource arrangement in the frequency domain3) Synchronization signals to be referred to (including SLSS (Sidelink Synchronization Signal))4) Reference signal used for path-loss measurement for transmission power control

In addition, with regard to OFDM (Orthogonal Frequency Division Multiplexing) of SL or UL, any of CP-OFDM (Cyclic-Prefix OFDM), DFT-S-OFDM (Discrete Fourier Transform-Spread-OFDM), OFDM without Transform precoding, and OFDM with Transform precoding may be applied.

In LTE SL, with regard to allocating SL resources to the terminals20, a Mode 3 and a Mode 4 are specified. In Mode 3, the transmission resources are dynamically allocated using a DCI (Downlink Control Information) that is transmitted from a base station10to a terminal20. In addition, in Mode 3, SPS (Semi Persistent Scheduling) is also available. In Mode 4, a terminal20autonomously selects transmission resources from a resource pool.

Note that a slot in an embodiment of the present invention may be read as a symbol, a mini slot, a subframe, a radio frame, or a TTI (Transmission Time Interval). In addition, a cell in an embodiment of the present invention may be read as a cell group, a carrier component, a BWP, a resource pool, a resource, a RAT (Radio Access Technology), a system (including a wireless LAN), and the like.

Note that, in an embodiment of the present invention, the terminal20is not limited to V2X terminals, but may be any type of terminal that performs D2D communication. For example, the terminal20may be a terminal that is carried by a user, such as a smartphone, or may be an IoT (Internet of Things) device such as a smart meter.

FIG.2is a drawing illustrating an example (1) of a V2X transmission mode. In the transmission mode of the sidelink communication shown inFIG.2, in step 1, a base station10transmits a sidelink scheduling to a terminal20A. Next, the terminal20A transmits PSCCH (Physical Sidelink Control Channel) and PSSCH (Physical Sidelink Shared Channel) to a terminal20B based on the received scheduling (step 2). The transmission mode of the sidelink communication shown inFIG.2may be called a sidelink transmission mode 3 in LTE. In the sidelink transmission mode 3 in LTE, Uu based sidelink scheduling is performed. Uu is a radio interface between UTRAN (Universal Terrestrial Radio Access Network) and UE (User Equipment). Note that, the transmission mode of the side link communication shown inFIG.2may be referred to as a side link transmission mode 1 in NR.

FIG.3is a drawing illustrating an example (2) of a V2X transmission mode. In the transmission mode of the sidelink communication shown inFIG.3, in step 1, a terminal20A transmits PSCCH and PSSCH to a terminal20B using autonomously selected resources. The transmission mode of the sidelink communication shown inFIG.3may be called a sidelink transmission mode 4 in LTE. In the sidelink transmission mode 4 in LTE, the UE itself performs resource selection.

FIG.4is a drawing illustrating an example (3) of a V2X transmission mode. In the transmission mode of the sidelink communication shown inFIG.4, in step 1, a terminal20A transmits PSCCH and PSSCH to a terminal20B using autonomously selected resources. Similarly, the terminal20B transmits PSCCH and PSSCH to the terminal20A using autonomously selected resources (step 1). The transmission mode of the sidelink communication shown inFIG.4may be called a sidelink transmission mode 2a in NR. In the sidelink transmission mode 2 in NR, the terminal20itself performs resource selection.

FIG.5is a drawing illustrating an example (4) of a V2X transmission mode. In the transmission mode of the sidelink communication shown inFIG.5, in step 0, a side link resource pattern is transmitted from a base station10to a terminal20A via RRC (Radio Resource Control) settings, or is set in advance. Next, the terminal20A transmits PSSCH to a terminal20B based on the resource pattern (step 1). The transmission mode of the sidelink communication shown inFIG.5may be called a sidelink transmission mode 2c in NR.

FIG.6is a drawing illustrating an example (5) of a V2X transmission mode. In the transmission mode of the sidelink communication shown inFIG.6, in step 1, a terminal20A transmits a sidelink scheduling to a terminal20B via PSCCH. Next, the terminal20B transmits PSSCH to the terminal20A based on the received scheduling (step 2). The transmission mode of the sidelink communication shown inFIG.6may be called a sidelink transmission mode 2d in NR.

FIG.7is a drawing illustrating an example (1) of a V2X communication type. The sidelink communication type shown inFIG.7is unicast. A terminal20A transmits PSCCH and PSSCH to a terminal20. In the example shown inFIG.7, the terminal20A performs unicast to a terminal20B, and performs unicast to a terminal20C.

FIG.8is a drawing illustrating an example (2) of a V2X communication type. The sidelink communication type shown inFIG.8is group-cast. A terminal20A transmits PSCCH and PSSCH to a group to which one or more terminals20belong. In the example shown inFIG.8, the group includes a terminal20B and a terminal20C, and the terminal20A performs groupcast to the group.

FIG.9is a drawing illustrating an example (3) of a V2X communication type. The sidelink communication type shown inFIG.9is broadcast. A terminal20A transmits PSCCH and PSSCH to one or more terminals20. In the example shown inFIG.9, the terminal20A performs broadcast to a terminal20B, a terminal20C, and a terminal20D. Note that, the terminals20A shown inFIG.7toFIG.9may be referred to as a header-UE.

In addition, in NR-V2X, it is assumed that HARQ (Hybrid automatic repeat request) is supported for unicasts and groupcasts of sidelinks. Furthermore, in NR-V2X, SFCI (Sidelink Feedback Control Information) including an HARQ response is defined. Furthermore, the transmission of SFCI via PSFCH (Physical Sidelink Feedback Channel) is also under consideration.

Note that, in the following description, PSFCH is used for transmitting a sidelink HARQ-ACK. However, this is just an example. For example, PSCCH may be used to transmit a sidelink HARQ-ACK, PSSCH may be used to transmit a sidelink HARQ-ACK, or other channels may be used to transmit a sidelink HARQ-ACK.

Hereafter, for the sake of convenience, the overall information reported by the terminal20in HARQ may be called HARQ-ACK. This HARQ-ACK may also be referred to as HARQ-ACK information. More specifically, the codebook applied to the HARQ-ACK information reported from the terminal20to a base station10and the like, is called the HARQ-ACK codebook. The HARQ-ACK codebook defines a bit sequence of HARQ-ACK information. Note that, NACK is also transmitted in addition to ACK by “HARQ-ACK”.

FIG.10is a sequence chart showing an example (1) of V2X operation. As shown inFIG.10, the wireless communication system according to an embodiment of the present invention may have a terminal20A and a terminal20B. Note that, there are many user apparatuses in actuality; however,FIG.10shows the terminal20A and the terminal20B as examples.

Hereafter, when the terminals20A,20B and the like are not particularly distinguished, they are simply described as “terminals 20” or “user apparatuses”.FIG.10illustrates, as an example, the case where the terminal20A and the terminal20B are both in cell coverage, but the operation according to an embodiment of the present invention is also applicable when the terminal20B is outside of coverage.

As mentioned above, in an embodiment of the present invention, the terminal20is, for example, a device installed in a vehicle, such as an automobile, and has a function of cellular communication as a UE in LTE or NR and a sidelink function. The terminal20may be a conventional portable terminal (such as a smartphone). The terminal20may also be an RSU. Such RSU may be a UE-type RSU having the function of a UE or a gNB-type RSU having the function of a base station apparatus.

Note that, the terminal20need not be a single housing device. For example, even if various sensors are distributed throughout the vehicle, the device including the various sensors may be the terminal20.

In addition, the processing contents of the transmission data of sidelink of the terminal20are basically the same as the processing contents of the UL transmission in LTE or NR. For example, the terminal20scrambles the code words of the transmission data, modulates them to generate complex-valued symbols, and maps the complex-valued symbols (transmission signals) to one or two layers for precoding. The precoded complex-valued symbols are then mapped to resource elements to generate a transmission signal (for example, complex-valued time-domain SC-FDMA signal), which is transmitted from each antenna port.

Note that, the base station10has a function of cellular communication as a base station in LTE or NR, and a function to enable the communication of the terminal20according to the present embodiment (for example, resource pool configuration, and resource allocation). In addition, the base station10may be an RSU (gNB -type RSU).

In addition, in a wireless communication system according to an embodiment of the present invention, a signal waveform used by the terminal20for SL or UL may be OFDMA, SC-FDMA, or another signal waveform.

In step S101, the terminal20A autonomously selects resources to be used for PSCCH and PSSCH from a resource selection window having a predetermined time period. The resource selection window may be configured from the base station10to the terminal20. Here, with regard to the predetermined time period of the resource selection window, the period may be defined by the terminal implementation conditions, such as processing time or maximum allowable packet delay time, or the period may be defined in advance by specifications, or the predetermined time period may be called an interval in the time domain.

In step S102and step S103, the terminal20A transmits SCI (Sidelink Control Information) by PSCCH and/or PSSCH and SL data by PSSCH, using the resources selected autonomously in the step S101. For example, the terminal20A may transmit the PSCCH using a frequency resource adjacent to the frequency resource of the PSSCH in the same time resource as at least part of the time resource of the PSSCH.

A terminal20B receives the SCI (PSCCH and/or PSSCH) and SL data (PSSCH) transmitted from the terminal20A. The received SCI may include information of the PSFCH resources for the terminal20B to transmit an HARQ-ACK for receiving such data. The terminal20A may include information of the autonomously selected resources in the SCI and transmit it.

In step S104, the terminal20B transmits an HARQ-ACK for the received data to the terminal20A using the resources of the PSFCH determined from the received SCI.

In step S105, the terminal20A retransmits the PSCCH and PSSCH to the terminal20B if the HARQ-ACK received in step S104indicates that retransmission is requested, i.e., in the case of NACK (negative response). The terminal20A may retransmit the PSCCH and PSSCH using autonomously selected resources.

Note that, if the HARQ control with HARQ feedback is not performed, the steps S104and S105need not be performed.

FIG.11is a sequence chart showing an example (2) of V2X operation. A blind retransmission without HARQ control may be performed to improve transmission success rate or reachability.

In step S201, a terminal20A autonomously selects resources to be used for PSCCH and PSSCH from a resource selection window having a predetermined time period. The resource selection window may be configured from the base station10to the terminal20.

In step S202and step S203, the terminal20A transmits SCI by PSCCH and/or PSSCH and SL data by PSSCH, using the resources selected autonomously in step S201. For example, the terminal20A may transmit the PSCCH using a frequency resource adjacent to the frequency resource of the PSSCH in the same time resource as at least part of the time resource of the PSSCH.

In step S204, the terminal20A retransmits the SCI by PSCCH and/or PSSCH and the SL data by PSSCH to the terminal20B, using the resources selected autonomously in step S201. The retransmission in step S204may be performed a plurality of times.

Note that, if blind retransmission is not performed, step S204need not be performed.

FIG.12is a sequence chart showing an example (3) of V2X operation. A base station10may perform a sidelink scheduling. That is, the base station10may determine the resources of the sidelink to be used by a terminal20to transmit information indicating such resources to a terminal20. Furthermore, if HARQ control with HARQ feedback is applied, the base station10may transmit information indicating the resources of PSFCH to the terminal20.

In step S301, the base station10performs SL scheduling by transmitting DCI (Downlink Control Information) to a terminal20A by PDCCH. Hereafter, for the sake of convenience, the DCI for SL scheduling is called SL scheduling DCI.

In addition, in step S301, it is assumed that the base station10also transmits DCI for DL scheduling (which may be called DL allocation) to the terminal20A by PDCCH. Hereafter, for the sake of convenience, the DCI for DL scheduling is called DL scheduling DCI. The terminal20A that has received the DL scheduling DCI receives DL data by PDSCH using the resources specified in the DL scheduling DCI.

In step S302and step S303, the terminal20A transmits SCI (Sidelink Control Information) by PSCCH and/or PSSCH and SL data by PSSCH, using the resources specified in the SL scheduling DCI. Note that, only the resources of PSSCH may be specified in the SL scheduling DCI. In this case, for example, the terminal20A may transmit the PSCCH using a frequency resource adjacent to the frequency resource of the PSSCH in the same time resource as at least part of the time resource of the PSSCH.

A terminal20B receives the SCI (PSCCH and/or PSSCH) and SL data (PSSCH) transmitted from the terminal20A. The SCI received by the PSCCH and/or PSSCH includes information of the resources of the PSFCH for the terminal20B to transmit an HARQ-ACK for receiving such data.

The information of the resource is included in the DL scheduling DCI or SL scheduling DCI transmitted from the base station10in step S301, and the terminal20A obtains the information of the resource from the DL scheduling DCI or SL scheduling DCI and includes it in the SCI. Alternatively, the DCI transmitted from the base station10need not include information of the resource, and the terminal20A may autonomously include information of the resource in the SCI and then transmit it.

In step S304, the terminal20B transmits an HARQ-ACK for the received data to the terminal20A using the resources of the PSFCH determined from the received SCI.

In step S305, the terminal20A transmits an HARQ-ACK at the timing (for example, slot unit timing) specified by the DL scheduling DCI (or SL scheduling DCI) using the PUCCH (Physical uplink control channel) resource specified by the DL scheduling DCI (or the SL scheduling DCI), and the base station10receives the HARQ-ACK. The codebook of the HARQ-ACK may include an HARQ-ACK generated based on an HARQ-ACK received from terminal20B or a PSFCH not received, and an HARQ-ACK for DL data. However, when there is no DL data allocation and the like, the HARQ-ACK for DL data is not included. In NR Rel. 16, the codebook of the HARQ-ACK does not include the HARQ-ACK for DL data.

Note that, if HARQ control with HARQ feedback is not performed, step S304and/or step S305need not be performed.

FIG.13is a sequence chart showing an example (4) of V2X operation. In the NR sidelink as described above, the transmission of an HARQ response is supported by PSFCH. Note that, a PSFCH format that can be used is the same as, for example, PUCCH (Physical Uplink Control Channel) format 0. That is, the PSFCH format may be a sequence-based format where the PRB (Physical Resource Block) size is 1 and an ACK and a NACK are identified by sequence and/or cyclic shift differences. The PSFCH format is not limited to this. The PSFCH resources may be placed in the last symbol or a plurality of symbols at the end of a slot. In addition, A period N may be configured for the PSFCH resources or may be predefined. The period N may be configured or predefined in slot units.

InFIG.13, the vertical axis corresponds to the frequency domain and the horizontal axis corresponds to the time domain. PSCCH may be placed in one symbol at the beginning of a slot, in a plurality of symbols from the beginning, or in a plurality of symbols from a symbol other than the beginning. PSFCH may be placed in one symbol at the end of the slot or in a plurality of symbols at the end of the slot. Note that, for the aforementioned “beginning of the slot” and “end of the slot”, consideration of symbols for AGC (Automatic Gain Control) and symbols for transmission /reception switching may be omitted. That is, for example, in a case where a slot includes 14 symbols, “beginning of the slot” and “end of the slot” may mean t the first symbols and the end symbols from among the 12 symbols, excluding the first symbol and the last symbol. In an example shown inFIG.13, three subchannels are configured in the resource pool, and two PSFCHs are placed in the third slot after a slot in which the PSSCH is placed. The arrows from PSSCH to PSFCH show examples of PSFCHs associated with PSSCHs.

In a case where an HARQ response in the NR-V2X groupcast is groupcast option 2 that transmits an ACK or NACK, it is necessary to determine the resources to be used for transmission and reception of PSFCH. As shown inFIG.13, in step S401, a terminal20A, which is a transmission side terminal20, performs groupcast to terminals20B,20C, and20D, which are reception side terminals20, via SL-SCH. Next, in step S402, the terminal20B uses PSFCH #B, the terminal20C uses PSFCH #C, and the terminal20D uses PSFCH #D to transmit the HARQ response to the terminal20A. Here, as shown in the example inFIG.13, in a case where the number of available PSFCH resources is less than the number of20reception side terminals belonging to the group, it is necessary to determine how to allocate the PSFCH resources. Note that, the transmission side terminals20may be aware of the number of reception side terminals20in groupcast. Note that, in the groupcast option 1, only a NACK is transmitted as an HARQ response, and an ACK is not transmitted.

FIG.14is a drawing showing an example of a sensing operation in LTE. When partial sensing is not configured by an upper layer in the LTE sidelink, a terminal20selects resources and transmits them as shown inFIG.14. As shown inFIG.14, the terminal20performs sensing in a sensing window in a resource pool. Sensing enables the terminals20to receive a resource reservation field included in SCI transmitted from another terminal20and to identify available resource candidates in a resource selection window in the resource pool based on the received field. Next, the terminal20randomly selects resources from the available resource candidates. The resource selection window is a set of candidate resources to be used that are configured in the resource pool. The resource selection window may be called by other names, for example, configurations for resource selection, and target section for resource selection. The sensing window in LTE may be an interval between a predetermined time point in the past and a time point immediately before a trigger such as packet generation. Sensing all resources within the sensing window may be called full sensing. Note that, the sensing window may have another name that indicates the interval for sensing.

Further, as shown inFIG.14, the resource pool configurations may have a period. For example, the period may be 10,240 milliseconds.FIG.14illustrates an example of configuring subframe t0SLto subframe tTmaxSLas a resource pool. Areas may be configured in the resource pool within the period, by means of, for example, a bitmap.

Further, as shown inFIG.14, the transmission trigger at the terminal20occurs in subframe n; and, the priority of the transmission is pTX. The terminals20can detect, for example, that another terminal20is performing transmission with priority pTXin the sensing window from subframe tn-10×PstepSLto subframe tn-1SL. In a case where SCI is detected in the sensing window and the RSRP (Reference signal received power) exceeds a threshold value, the resource in the resource selection window corresponding to the SCI is excluded. In addition, in a case where SCI is detected in the sensing window and the RSRP is less than the threshold value, the resource in the resource selection window corresponding to the SCI is not excluded. The threshold value may be, for example, the threshold value ThpTx,pRXconfigured or defined for each resource in the sensing window based on the priority pTXand the priority pRX.

Further, the resources in the resource selection window that serve as candidates for resource reservation information, corresponding to the resources in the sensing window that are unmonitored, for example, due to transmission, are excluded, as in the subframe tzSLshown inFIG.14.

In the resource selection window from subframe n+T1to subframe n+T2, as shown inFIG.14, the resources occupied by another UE are identified and the resources excluding such resources serve as available resource candidates. In a case where the set of available resource candidates is SAand SAis less than 20% of the resources in the resource selection window, the resources may be identified again by increasing the threshold value ThpTx,pRXconfigured for each resource in the sensing window by 3 dB. That is, by increasing the threshold value ThpTx,pRXand identifying the resource again, the resources, which are not excluded because their RSRP is less than the threshold value, may be increased. Furthermore, the RSSI (Received signal strength indicator) of each resource in the SAmay be measured and the resource with the smallest RSSI may be added to a set SB. The operation of adding the resource with the smallest RSSI contained in SAto the SBmay be repeated until the set of resource candidates SBis at least 20% of the resource selection window.

A lower layer of the terminal20may report the SBto an upper layer. The upper layer of the terminal20may perform random selection with respect to the SBto determine resources to be used. The terminal20may perform sidelink transmission using the determined resources. Note that once the resources are secured, the terminal20may use the resources periodically without performing sensing a predetermined number of times (for example, Creseltimes).

FIG.15is a drawing showing an example of a partial sensing operation in LTE. When the partial sensing is configured by an upper layer in the LTE sidelink, the terminal20selects resources and transmits them as shown inFIG.15. As shown inFIG.15, the terminal20performs partial sensing for a portion of the sensing window in the resource pool. A resource for which partial sensing is performed may be referred to as a sensing target, a sensing object, a sensing subframe, or a sensing slot. Partial sensing enables the terminals20to receive a resource reservation field included in SCI transmitted from another terminal20and to identify available resource candidates in a resource selection window in the resource pool based on the received field. Next, the terminal20randomly selects resources from the available resource candidates.

Further, as shown inFIG.15, the resource pool configurations may have a period. For example, the period may be 10,240 milliseconds.FIG.15illustrates an example of configuring subframe t0SLto subframe tTmaxSLas a resource pool. Target areas may be configured in the resource pool within the period, by means of, for example, a bitmap.

As shown inFIG.15, the transmission trigger at the terminal20occurs in subframe n; and, the priority of the transmission is pTX. As shown inFIG.15, among the subframes n+T1to the subframe n+T2, Y subframes from the subframe tySLto the subframe ty+Y-1SLmay be configured as a resource selection window. Furthermore, as shown inFIG.15, the transmission trigger at the terminal20occurs in subframe n; and, the priority of the transmission is pTX.

The terminals20can detect, for example, that another terminal20performs transmission with prioritypRXin one or more sensing targets from the subframe ty-k×PstepSLto subframe ty+Y-k×Pstep-1SL, which is Y subframes in length. The k may be, for example, a 10-bit bitmap.FIG.15illustrates an example of configuring the third and sixth bits of a bitmap k to “1” that indicates that partial sensing is to be performed. That is, inFIG.15, the subframe ty-6×PstepSLto subframe ty+Y-6×Pstep-1SLand subframe ty-3×PstepSLto subframe ty+Y-3×Pstep-1SLare configured as sensing targets. As mentioned above, the i-th bit of the bitmap k may correspond to the sensing targets from subframe ty-ixPstepSLto subframe ty+Y-ixPstep-1SL.

Note that, y is an index in the Y subframes, k is configured or defined in advance in a 10-bit bitmap, and Pstepis 100 ms. However, in performing SL communication on DL and UL carriers, Pstepis (U/(D+S+U)) *100 ms, where U is the number of UL slots, D is the number of DL slots, and S is the number of special slots.

In a case where SCI is detected in one or more of the above sensing targets and the RSRP exceeds a threshold value, the resource in the resource selection window corresponding to the resource reservation field of the SCI is excluded. In addition, in a case where SCI is detected in the sensing targets and the RSRP is less than the threshold value, the resource in the resource selection window corresponding to the resource reservation field of the SCI is not excluded. The threshold value may be, for example, the threshold value ThpTX,pRXconfigured or defined for each resource in the sensing window, based on the priority pTXand the priority pRX.

As shown inFIG.15, in the resource selection window where Y subframes are configured in the interval [n+T1, n+T2], the terminal20identifies the resources occupied by other UEs, and resources excluding such resources serve as available resource candidates. Note that, the Y subframes do not have to be contiguous. In a case where the set of available resource candidates is SAand SAis less than 20% of the resources in the resource selection window, the resources may be identified again by increasing the threshold value ThpTx,pRXconfigured for each resource in the sensing window by 3 dB. That is, by increasing the threshold value ThpTx,pRXand identifying the resource again, the resources, which are not excluded because their RSRP is less than the threshold value, may be increased. Furthermore, the RSSI of each resource in the SAmay be measured and the resource with the smallest RSSI may be added to a set SB. The operation of adding the resource with the smallest RSSI contained in SAto the SBmay be repeated until the set of resource candidates SBis at least 20% of the resource selection window.

A lower layer of the terminal20may report the SBto an upper layer. The upper layer of the terminal20may perform random selection with respect to the SBto determine resources to be used. The terminal20may perform sidelink transmission using the determined resources. Note that once the resources are secured, the terminal20may use the resources periodically without performing sensing a predetermined number of times (for example, Creseltimes).

FIG.16is a drawing showing an example of a sensing operation in NR. In the resource allocation mode 2, a terminal20selects resources and then transmits them. As shown inFIG.16, the terminal20performs sensing in a sensing window in a resource pool. Sensing enables the terminals20to receive a resource reservation field or a resource assignment field included in SCI transmitted from another terminal20and to identify available resource candidates in a resource selection window in the resource pool based on the field. Next, the terminal20randomly selects resources from the available resource candidates.

Further, as shown inFIG.16, the resource pool configurations may have a period. For example, the period may be 10,240 milliseconds.FIG.16illustrates an example of configuring the slots from t0SLto tTmaxSLas a resource pool. Areas may be configured in the resource pool within the period, by means of, for example, a bitmap.

Further, as shown inFIG.16, the transmission trigger at the terminal20occurs in slot n; and, the priority of the transmission is pTX. The terminals20can detect, for example, that another terminal20is performing transmission with priority pRXin the sensing window from slot n-T0to the slot immediately before slot n-Tproc,0. In a case where SCI is detected in the sensing window and the RSRP (Reference Signal Received Power) exceeds a threshold value, the resource in the resource selection window corresponding to the SCI is excluded. In addition, in a case where SCI is detected in the sensing window and the RSRP is less than the threshold value, the resource in the resource selection window corresponding to the SCI is not excluded. The threshold value may be, for example, the threshold value ThpTx,pRXconfigured or defined for each resource in the sensing window based on the priority pTXand the priority pRX.

Further, the resources in the resource selection window that serve as candidates for resource reservation information, corresponding to the resources in the sensing window that are unmonitored, for example, due to transmission, are excluded, as in the slot tmSLshown inFIG.16.

In the resource selection window from slot n+T1to slot n+T2, as shown inFIG.16, the resources occupied by other UEs are identified and the resources excluding such resources serve as available resource candidates. In a case where the set of available resource candidates is SAand SAis less than 20% of the resource selection window, the resources may be identified again by increasing the threshold value ThpTx,pRXset for each resource in the sensing window by 3 dB. That is, by increasing the threshold value ThpTx,pRXand identifying the resource again, the resources, which are not excluded because their RSRP is less than the threshold value, may be increased, so that the set SAof the resource candidates is at least 20% of the resource selection window. In a case where the SAis less than 20% of the resource selection window, the operation of identifying resource again with a 3 dB increase in the threshold value ThpTx,pRXset for each resource in the sensing window may be repeated.

A lower layer of the terminal20may report the SAto an upper layer. The upper layer of the terminal20may perform random selection with respect to the SAto determine resources to be used. The terminal20may perform sidelink transmission using the determined resources.

FIGS.14,15and16describe the operation of the transmission side terminals20; however, the reception side terminals20may detect, based on the results of sensing or partial sensing, the data transmission from other terminals20and receive data from the other terminals20.

Power saving based on the above random resource selection and partial sensing is being discussed in the NR Release 17 sidelink. For example, for power saving, the random resource selection and the partial sensing of the side link in LTE release 14 may be applied to the resource allocation mode 2 of the NR release 16 sidelink. The terminal20, where partial sensing is applied, performs reception and sensing only in specific slots within the sensing window.

In addition, eURLLC (enhanced Ultra Reliable Low Latency Communication) is being discussed in the NR Release 17 sidelink, using inter-UE coordination as a base line. For example, the terminal20A may share information indicating the resource set with the terminal20B, and the terminal20B may take into account the information in the resource selection for transmission.

In resource allocation mode 2, in which the terminals20autonomously select resources, the resource reservation information of other terminals20is received through sensing, and based on such resource reservation information, the terminals20select the resources to be used for transmission. Here, the information received from sensing is the information at the location of the transmission side terminal20.

In another aspect, whether the quality of the resources selected by the transmission side terminals20is actually good or bad (for example, whether there is no interference or interference is small) also depends on the location of the reception side terminals20. For example, there is a hidden terminal problem in which a third terminal20, which is undetectable from the transmission side terminal20, may be in a position that causes interference to the reception side terminal20.

FIG.17is a drawing showing an example (1) of D2D communication. An example of the hidden terminal problem includes, as shown inFIG.17, a case where a reception side terminal20A is positioned between a transmission side terminal20B transmitting via resource #A and a third terminal20C transmitting via the resource #A.

FIG.18is a drawing showing an example (2) of D2D communication. As an example of the hidden terminal problem, as shown inFIG.18, in a case where a third terminal20C transmitting via resource #A is positioned out of sight due to buildings and the like from the transmission side terminal20B transmitting via the resource #A, and positioned in sight from a reception side terminal20A, the interference from the terminal20C is significantly different between the terminal20A and the terminal20B.

Therefore, the terminal20that has received the resource reservation information from different terminals20for reserving the same resource may transmit specific information to a specific terminal20.

The terminal20that has received the reservation information from different terminals20for reserving the same resource may refer to a terminal that satisfies at least one of the conditions shown in 1) to 7) below. Note that, the PC5-RRC connection refers to the RRC connection between the terminals20. Further, reserving the same resource may also mean that at least one of the plurality of resources is the same resource in the case of a reservation signal that reserves the plurality of resources.1) Received the reservation information for reserving the same resource, where the destination of any reservation information is addressed to the terminal itself2) Received the reservation information for reserving the same resource, where the destination of at least one of the reservation information is addressed to the terminal itself and the destination of at least one of the reservation information is not addressed to the terminal itself3) Received the reservation information received by unicast, groupcast, or broadcast4) Received the reservation information from the terminal20, where a PC5 -RRC connection is established with the terminal itself5) Received the reservation information (for example, reservation by time resource assignment field) to make aperiodic reservation6) The reservation information is received to make periodic reservation by the resource reservation period field7) At least one of the received RSRP and priority related to the received reservation information satisfies predetermined conditionsNote that, the predetermined conditions in 7) above may be, for example, any of the followinga) A plurality of reservation information for reserving the same resource is received, and the value or difference of the received RSRPs is greater or smaller than a predetermined valueb) A plurality of reservation information for reserving the same resource is received, and the received RSRP of the reservation information with higher priority is smaller than the received RSRP of the reservation information with lower priority, or smaller by XdB or more

FIG.19is a drawing showing an example (1) of D2D communication according to an embodiment of the present invention. As shown inFIG.19, a terminal20B, which reserves resource #A, transmits to a terminal20A, and a terminal20C, which reserves resource #A, transmits to the terminal20A. That is, inFIG.19, the aforementioned condition 1) is satisfied, in which the reservation information is received, for which the destination of reservation information for reserving the same resource is the terminal20A.

FIG.20is a drawing showing an example (2) of D2D communication according to an embodiment of the present invention. As shown inFIG.20, a terminal20B, which reserves resource #A, transmits to a terminal20A, and a terminal20C, which reserves resource #A, transmits to a terminal D other than the terminal20A. That is, inFIG.20, the aforementioned condition 2) is satisfied, in which the reservation information for reserving the same resource is received, where the destination of at least one of the reservation information is addressed to the terminal itself and the destination of at least one of the reservation information is not addressed to the terminal itself.

By defining the terminal20that has received the reservation information from different terminals20for reserving the same resource as described above, it is possible to prevent transmissions in which the same resource is used.

The terminal20that has received the resource reservation information from different terminals20for reserving the same resource may transmit specific information to a specific terminal20determined based on at least one of 1) to 12) below.1) At least one terminal20from among the terminals20that have transmitted the resource reservation information.2) N-1 terminals20from among N terminals20that have transmitted the resource reservation information.3) The terminal20determined based on the destination of the resource reservation information.FIG.21is a drawing showing an example (3) of D2D communication according to an embodiment of the present invention. For example, the specific information may be transmitted to a terminal20B that has transmitted the resource reservation information whose destination includes the sensing terminal20A shown inFIG.21. The specific information may also be transmitted to a terminal20C that has transmitted the resource reservation information whose destination is a destination (for example, terminal20D) that does not include the sensing terminal20A shown inFIG.21.4) The terminals20determined based on the PC5-RRC connection. For example, the terminal20that has established a PC5-RRC connection with the sensing terminal20, from among the terminals20that have transmitted the resource reservation information. For example, the terminal20that has not established a PC5-RRC connection with the sensing terminal20, from among the terminals20that have transmitted the resource reservation information.5) The terminals20determined based on the periodicity related to the reservation. For example, the terminal20that has made periodic reservations (for example, reservations via resource reservation periodic field) based on the resource reservation information. In addition, the terminal20that has made aperiodic reservations (for example, reservations via time resource assignment field) based on the resource reservation information. In addition, for example, the terminal20that has made a reservation with a period smaller than the value determined based on specific conditions.6) The terminal20determined based on priority. For example, the terminal20that has transmitted the reservation with the lowest priority related to the resource reservation information.7) The terminal20determined based on the Packet delay budget (PDB). For example, the terminal20that has performed transmission with a large PDB of the transport block related to the resource reservation information. For example, the terminal20that has performed transmission with a large remaining time up to PDB of the transport block related to the resource reservation information.8) The terminal20determined based on the number of reserved resources. For example, the terminal20with a large number of reserved resources according to the resource reservation information.9) The terminal20determined based on the received RSRP related to the resource reservation information. For example, the terminal20with a large or small received RSRP related to the resource reservation information.10) The terminal20determined based on the cast type of the resource reservation information. For example, the terminal20whose resource reservation information is a reservation for broadcast transmission.11) All of the terminals20that have transmitted the resource reservation information.12) All terminals20. For example, the sensing terminal20may broadcast specific information.

Note that, in a case where at least one terminal20from among the terminals20shown in the aforementioned 3) to 12) is identified and the number of identified terminals20does not satisfy the aforementioned 1) or 2), the identified terminals20may be further added or deleted based on the terminal implementation.

By defining the terminal20to which the specific information is to be transmitted from the terminal20that has received the reservation information from different terminals20for reserving the same resource as described above, it is possible to prevent transmissions in which the same resource is used.

The terminal20that has received the resource reservation information from different terminals20for reserving the same resource may transmit the specific information shown in at least one of 1) to 6) below to the specific terminal20.1) Information indicating that a collision has been detected.2) Information indicating a recommendation or request for changing resources. Note that, the recommendation means that the terminals20receiving the information do not have to comply with it, while the request means that the terminals20receiving the information must comply with it.FIG.22is a drawing showing an example (4) of D2D communication according to an embodiment of the present invention. As shown inFIG.22, a terminal20A may transmit information requesting a resource change to a terminal20C that reserves the transmission to a terminal20D other than the sensing terminal20A.3) Information indicating a recommendation or request for not using the resource.4) A recommendation or request for changing transmission power. The transmission power difference from the signal related to the reservation may be indicated, or an absolute value of the transmission power may be indicated.5) Information indicating the target resource. For example, the slot index and/or offset may be indicated, and in a case where the reservation is periodic, the resource number may be indicated.6) Information indicating a value or a range of priority to be transmitted with the resource. For example, “only transmission with a priority value of X or less is possible” may be indicated. The information may be transmitted by broadcast.

The method of transmitting specific information as shown in the aforementioned 1) to 6) may be the method shown in 1) to 3) below.1) Physical Layer Signaling. For example, SCI, PSCCH, S-SSB, PSFCH or a newly defined channel.2) MAC (Medium Access Control) Signaling. For example, MAC-CE (Control element).3) RRC Signaling. For example, a PC5-RRC message.

The terminal20, upon receiving the specific information as shown in the aforementioned 1) to 6), may perform the operation as shown in 1) to 5) below.1) Reselect resources based on the specific information. For example, as shown inFIG.22, a terminal20C, upon receiving specific information from a sensing terminal20A requesting a resource change, may select a new resource #B to be transmitted to a terminal20D other than the terminal20A.2) Drop resources based on the specific information.3) Change the transmission power based on the specific information.4) Perform an operation according to the terminal implementation based on the specific information.5) Perform a preemption operation based on the specific information. Note that, the preemption may mean the following operations.

FIG.23is a sequence chart showing an example of preemption in NR.FIG.24is a drawing showing an example of preemption in NR. In step S501, the terminal20performs sensing in a sensing window. In a case where the terminal20performs a power saving operation, the sensing may be performed for a predefined, limited period of time. Subsequently, the terminal20, based on the sensing results, identifies each resource in a resource selection window to determine a set of resource candidates SA(S502). Subsequently, the terminal20selects a resource set (r_0, r_1, ...) from the set of resource candidates SA(S503).

In step S504, the terminal20re-identifies each resource in the resource selection window based on the sensing results and based on the priority at the timing of T(r_0)-T3shown inFIG.24to determine the set of resource candidates SA. For example, with respect to r_1 shown inFIG.24, SCI transmitted from another terminal20is detected through sensing again. In a case where preemption is enabled, the terminal20excludes resource r_1 from the SAin a case where the value prio_RX, which indicates the priority of the SCI transmitted from another terminal20, is less than the value prio_TX, which indicates the priority of the transport block transmitted from the terminal itself. Note that, the lower the value indicating the priority, the higher the priority. That is, in a case where the value prio_RX, which indicates the priority of the SCI transmitted from another terminal20, is higher than the value prio_TX, which indicates the priority of the transport block transmitted from the terminal itself, the terminal20does not exclude resource r_1 from the SA.

In step S505, in a case where the SAdoes not include the resource r_i, the terminal20excludes r_i from the resource set (S505), updates the resource set, and terminates preemption.

Note that, as shown inFIG.22, the sensing terminal20A may receive data transmitted from the terminal20B in the resource #A. Note that, the sensing terminal20A may receive data from the terminal20, from which the reservation information is not received, other than the terminals20B and20C.

An embodiment of the present invention may be applied to the operation of a terminal20, i.e., the operation of configuring or allocating transmission resources of another terminal20. That is, the transmission resources of another terminal20may be configured or allocated so as to satisfy the conditions for resource selection or resource allocation according to an embodiment of the present invention.

The above-described embodiments are not limited to V2X terminals, but may be applied to the terminals that perform D2D communications.

The operations according to the above-described embodiments may be performed only in a specific resource pool. For example, the operations according to the above-described embodiments may be performed only in the resource pool that can be used by the terminals20of Release 17 or later release.

The operations according to the above-described embodiments may be applied to any case where the transmission is groupcast, the transmission is unicast, or the transmission is broadcast.

According to the above-described embodiments, the terminal20can transmit the specific information to another terminal20based on the reservation information through sensing, thereby preventing transmission collisions in resources transmitted to the device itself.

That is, in direct communication between terminals, the reliability of communication during autonomous resource selection can be improved.

Device Configuration

Next, an example of a functional configuration of the base station10and the terminal20that execute processes and operations described so far is described. The base station10and the terminal20have functions for performing the above embodiments. However, the base station10and the terminal20each may have only some of the functions in the embodiments.

FIG.25is a drawing showing an example of a functional configuration of a base station10. As shown inFIG.25, the base station10comprises a transmitting unit110, a receiving unit120, a configuring unit130, and a controlling unit140. The functional configuration shown inFIG.25is only an example. Any functional classification and any functional unit name may be used as long as the operations according to the embodiments of the present invention can be performed.

The transmitting unit110has a function of generating a signal to be transmitted to the terminal20side and transmitting the signal wirelessly. The receiving unit120has a function of receiving various signals transmitted from the terminal20and acquiring information of, for example, a higher layer from the received signals. In addition, the transmitting unit110has a function for transmitting NR-PSS, NR-SSS, NR-PBCH, DL/UL control signals, DL reference signals, and the like, to the terminal20.

The configuring unit130stores, in the storage device, the pre-configured configuration information and various configuration information to be transmitted to the terminal20and reads them from the storage device if necessary. The contents of the configuration information are, for example, information related to configuration of D2D communication.

The controlling unit140performs processing related to the settings for the terminals20to perform D2D communication, as described in the example. The controlling unit140also transmits the scheduling of D2D communication and DL communication to the terminal20via the transmitting unit110. The controlling unit140also receives information related to HARQ responses for D2D communication and DL communication from the terminal20via the receiving unit120. The functional unit related to signal transmission in the controlling unit140may be included in the transmitting unit110, and the functional unit related to signal reception in the controlling unit140may be included in the receiving unit120.

FIG.26is a drawing showing an example of a functional configuration of a terminal20. As shown inFIG.26, the terminal20comprises a transmitting unit210, a receiving unit220, a configuring unit230, and a controlling unit240. The functional configuration shown inFIG.26is only an example. Any functional classification and any functional unit name may be used as long as the operations according to the embodiments of the present invention can be performed.

The transmitting unit210generates a transmission signal from the transmission data and transmits the transmission signal wirelessly. The receiving unit220receives various signals wirelessly and acquires a signal of a higher layer from the received signal of a physical layer. In addition, the receiving unit220has a function for receiving NR-PSS, NR-SSS, NR-PBCH, DL/UL/SL control signals, or reference signals and the like transmitted from the base station10. Further, for example, the transmitting unit210, as D2D communication, transmits PSCCH (Physical Sidelink Control Channel), PSSCH (Physical Sidelink Shared Channel), PSDCH (Physical Sidelink Discovery Channel), PSBCH (Physical Sidelink Broadcast Channel) and the like to other terminals20, and the receiving unit220receives PSCCH, PSSCH, PSDCH, PSBCH and the like from other terminals20.

The configuring unit230stores, in the storage device, various configuration information received from the base station10or the terminal20via the receiving unit220, and reads them from the storage device if necessary. The configuring unit230also stores pre-configured configuration information. The contents of the configuration information are, for example, information related to configuration of D2D communication.

The controlling unit240controls the D2D communication to establish RRC connections between other terminals20, as described in the examples. The controlling unit240also performs processing related to the power saving operations. The controlling unit240also performs processing related to HARQ of D2D and DL communications. The controlling unit240also transmits, to the base station10, the information related to the HARQ response of the D2D and DL communications scheduled from the base station10to the other terminals20. The controlling unit240may also perform scheduling of D2D communication to the other terminals20. Further, the controlling unit240may autonomously select resources to be used for establishing the D2D communication based on the sensing results from the resource selection window, or may perform a re-evaluation or preemption. The controlling unit240also performs processing related to the power saving in the transmission and reception of the D2D communication. The controlling unit240also performs processing related to inter-UE coordination in D2D communication. The functional unit related to signal transmission in the controlling unit240may be included in the transmitting unit210, and the functional unit related to signal reception in the controlling unit240may be included in the receiving unit220.

Hardware Configuration

Block diagrams (FIG.25andFIG.26) used in the description of the embodiments above show blocks of each function unit. These functional blocks (configuration units) are achieved by any combination of at least one of hardware and software. Further, the method of achieving each functional block is not particularly limited. That is, each functional block may be achieved by using one physically or logically coupled device, by directly or indirectly (for example, in a wired or wireless manner) connecting two or more physically or logically separated devices, and by using these multiple devices. The functional block may be achieved by combining software with the one device above or the plurality of devices above.

For example, the base station10, the terminal20and the like in one embodiment of the present disclosure may function as a computer that processes the wireless communication methods of the present disclosure.FIG.27is a drawing showing an example of a hardware configuration of the base station10and the terminal20according to an embodiment of the present disclosure. The base station10and the terminal20above may be physically configured as a computer device including a processor1001, a storage device1002, an auxiliary storage device1003, a communication device1004, an input device1005, an output device1006, a bus1007and the like.

In the following description, term “device” can be understood as a circuit, a device, a unit and the like. A hardware configuration of the base station10and the terminal20may be configured to include one or more of the devices shown in the drawings or may be configured to not include some of the devices.

Each function in the base station10and the terminal20is achieved by the processor1001to perform calculation by loading a predetermined software (a program) on hardware such as the processor1001and the storage device1002, by controlling communication by the communication device1004, and by controlling at least one of reading and writing data on the storage device1002and the auxiliary storage device1003.

The processor1001, for example, operates an operating system to control the entire computer. The processor1001may be configured by a central processing unit (CPU) including an interface with a peripheral equipment, a control device, an arithmetic device, a register and the like. For example, the controlling unit140, the controlling unit240and the like above may be achieved by the processor1001.

Further, the processor1001reads a program (a program code), a software module, data and the like from at least one of the auxiliary storage device1003and the communication device1004into the storage device1002, and performs various processes according to the program, the software module and the data. For the program, a program that causes a computer to perform at least some of the operations described in the above embodiments is used. For example, the controlling unit140of the base station10shown inFIG.25may be included in the storage device1002and achieved by a control program operated on the processor1001. Further, for example, the controlling unit240of the terminal20shown inFIG.26may be included in the storage device1002and achieved by a control program operated on the processor1001. Although it has been described that the various processes described above are performed by one processor1001, these processes may be performed simultaneously or sequentially by two or more processors1001. The processor1001may be implemented by one or more chips. The program may be transmitted from a network via a telecommunication line.

The storage device1002is a computer-readable recording medium, and may be configured by at least one of, for example, ROM (Read Only Memory), EPROM (Erasable Programmable ROM), EEPROM (Electrically Erasable Programmable ROM), and RAM (Random Access Memory). The storage device1002may be called a register, a cache, a main memory (a main storage device) and the like. The storage device1002can store a program (a program code), a software module and the like that can be operate to implement a communication method according to one embodiment of the present disclosure.

The auxiliary storage device1003is a computer-readable recording medium, and may be configured by at least one of, for example, an optical disk such as a CD-ROM (Compact Disc ROM), a hard disk drive, a flexible disk, an optical magnetic disk (for example, a compact disk, a digital versatile disk, Blu-ray (registered trademark) disk), a smart card, a flash memory (for example, a card, a stick, a key drive), a floppy (registered trademark) disk, and a magnetic strip. The storage medium described above may be, for example, a database, a server or other suitable mediums including at least one of the storage device1002and the auxiliary storage device1003.

The communication device1004is hardware (a transmitting/receiving device) for communicating between computers via at least one of a wired network and a wireless network, and is also referred to as, for example, a network device, a network controller, a network card, and a communication module. The communication device1004may be configured to include, for example, a high frequency switch, a duplexer, a filter, and a frequency synthesizer in order to achieve at least one of frequency division duplex (FDD) and time division duplex (TDD). For example, a transmitting/receiving antenna, an amplifier unit, a transmitting/receiving unit, a transmission line interface and the like may be achieved by the communication device1004. The transmission/receiving unit may be implemented in a physically or logically separated manner between the transmitting unit and the receiving unit.

The input device1005is an input device (for example, a keyboard, a mouse, a microphone, a switch, a button, and a sensor) that receives input from outside. The output device1006is an output device (for example, a display, a speaker, and an LED lamp) that performs output to outside. The input device1005and the output device1006may have an integrated configuration (for example, a touch panel).

Further, each device such as the processor1001and the storage device1002is connected by a bus1007for communicating information. The bus1007may be configured by using a single bus, or may be configured by using a different bus for each device.

Further, the base station10and the terminal20may be configured to include hardware such as a microprocessor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a programmable logic device (PLD), and a field programmable gate array (FPGA), and some or all of the functional blocks may be achieved by the hardware. For example, the processor1001may be implemented using at least one of these hardware.

Summary of Embodiments

As described above, according to an embodiment of the present invention, a terminal is provided, comprising: a receiving unit configured to receive reservation information for reserving resources from a plurality of terminals, at least one of the reserved resources being a same resource; a controlling unit configured to identify a first terminal from among the plurality of terminals; and

a transmitting unit configured to transmit information related to the same resource to the first terminal, wherein the receiving unit receives data from a second terminal in the same resource.

According to the configuration above, the terminal20can transmit the specific information to another terminal20based on the reservation information through sensing, thereby preventing transmission collisions in resources transmitted to the device itself. That is, in direct communication between terminals, the reliability of communication during autonomous resource selection can be improved.

The controlling unit may identify, as the first terminal, a terminal that has transmitted the reservation information addressed to a different terminal among the plurality of terminals. According to the configuration, the terminal20can transmit the specific information to another terminal20based on the reservation information addressed to a terminal other than the device itself through sensing, thereby preventing transmission collisions in resources transmitted to the device itself.

The controlling unit may identify, as the first terminal, a terminal that has transmitted reservation information with low priority among the plurality of terminals. According to the configuration, the terminal20can transmit the specific information to another terminal20based on the reservation information with low priority through sensing, thereby preventing transmission collisions in resources transmitted to the device itself.

The transmitting unit may transmit, to the first terminal, information indicating an indication to use another resource without using the same resource. According to the configuration, the terminals20can transmit an indication to another terminal20to change the resource based on the reservation information through sensing, thereby preventing transmission collisions in the resource transmitted to the device itself.

The transmitting unit may transmit, to the first terminal, information indicating an occurrence of a collision in the same resource. According to the configuration, the terminals20can transmit the indication to another terminal20to change the transmission power in the resources based on the reservation information through sensing, thereby improving the quality of transmission in the resources transmitted to the device itself.

According to the disclosed technology, a communication method performed by a terminal is provided. The communication method includes: receiving reservation information for reserving resources from a plurality of terminals, at least one of the reserved resources being a same resource; identifying a first terminal from among the plurality of terminals; transmitting information related to the same resource to the first terminal; and receiving data from a second terminal in the same resource.

According to the configuration above, the terminal20can transmit the specific information to another terminal20based on the reservation information through sensing, thereby preventing transmission collisions in resources transmitted to the device itself. That is, in direct communication between terminals, the reliability of communication during autonomous resource selection can be improved.

Supplement to Embodiments

Although the embodiments of the present invention have been described above, the disclosed inventions are not limited to such embodiments, and those skilled in the art will understand various modifications, corrections, alternatives, substitutions, and the like. Although explanations have been given using specific numerical examples in order to promote understanding of the present invention, these numerical values are merely examples and any appropriate values may be used unless otherwise specified. Classification of items in the above description is not essential to the present invention, and elements described in two or more items may be used in combination as necessary, and an element described in one item may be applied to another element (as long as there is no contradiction) described in other items. A boundary of the functional unit or the processing unit in the functional block diagram does not necessarily correspond to a boundary of the physical components. Operations of the plurality of functional units may be physically performed by one component, or operations of one functional unit may be physically performed by a plurality of components. For the processing procedure described in the embodiments, the processing order may be changed as long as there is no contradiction. For convenience of description of processing, although the base station10and the terminal20have been described with reference to functional block diagrams, such devices may be implemented in hardware, software, or a combination thereof. Software operated by a processor of the base station10according to the embodiment of the present invention and software operated by a processor of the terminal20according to the embodiment of the present invention respectively may be stored in a random access memory (RAM), a flash memory, a read-only memory (ROM), EPROM, EEPROM, a register, a hard disk (HDD), a removable disk, CD-ROM, a database, a server or any other suitable storage medium.

Further, the indication of information is not limited to the aspects/embodiments described in the present disclosure, and may be performed by using other methods. For example, the indication of information may be performed by physical layer signaling (for example, DCI (Downlink Control Information), UCI (Uplink Control Information)), higher layer signaling (for example, RRC (Radio Resource Control) signaling, MAC (Medium Access Control) signaling, broadcast information (MIB (Master Information Block)), SIB (System Information Block)), other signals or a combination thereof. Further, RRC signaling may be called an RRC message and may be, for example, an RRC connection setup message, and an RRC connection reconfiguration message.

Each aspect/embodiment described in the present disclosure may be applied to at least one of LTE (Long Term Evolution), LTE-A (LTE-Advanced), SUPER 3G, IMT-Advanced, 4G (4th generation mobile communication system), 5G (5th generation mobile communication system), FRA (Future Radio Access), NR (new Radio), W-CDMA (registered trademark), GSM (registered trademark), CDMA2000, UMB (Ultra Mobile Broadband), IEEE 802.11 (Wi-Fi (registered trademark)), IEEE 802.16 (WiMAX (registered trademark)), IEEE 802.20, UWB (Ultra-WideBand), Bluetooth (registered trademark), a system using other suitable systems, and a next generation system expanded based on them. Further, a plurality of systems may be applied in a combination (for example, a combination of at least one of LTE and LTE-A and 5G).

The order of processing procedures, sequences, flowcharts, etc. of each aspect/embodiment described in the present specification may be changed as long as there is no contradiction. For example, the methods described in the present disclosure present elements of various steps using exemplary orders, and are not limited to the particular order presented.

The specific operation performed by the base station10in the present specification may be performed by its upper node in some cases. In a network consisting of one or more network nodes having the base station10, it is obvious that various operations performed for communication with the terminal20are performed by the base station10and at least one of other network nodes (for example, MME, and S-GW, but not limited to these) other than the base station10. In the above example, a case where there is one network node other than the base station10is illustrated, but other network nodes may be a combination of a plurality of the other network nodes (for example, MME and S-GW).

The information, signals, etc. described in the present disclosure may be output from an upper layer (or a lower layer) to a lower layer (or an upper layer). Input/output may be performed via a plurality of network nodes.

The input/output information and the like may be stored in a specific place (for example, a memory) or may be managed using a management table. Information to be input/output may be overwritten, updated or added. The output information and the like may be deleted. The input information and the like may be transmitted to the other device.

Determination in the present disclosure may be performed by a value represented by 1 bit (0 or 1), may be performed by a true/false value (Boolean: true or false), or may be performed by comparison of numerical values (for example, comparison with a predetermined value).

Software, whether called software, firmware, middleware, microcode, hardware description language, or other names, should be broadly interpreted to mean an instruction, an instruction set, a code, a code segment, a program code, a program, a subprogram, a software module, an application, a software application, a software package, a routine, a subroutine, an object, an executable file, an execution thread, a procedure, a feature, and the like.

Further, software, an instruction, information, and the like may be transmitted and received via a transmission medium. For example, if software uses at least one of wired technology (coaxial cable, optical fiber cable, twisted pair, digital subscriber line (DSL), etc.) and wireless technology (infrared, microwave, etc.) and is transmitted from a website, a server or other remote sources, at least one of these wired and wireless technologies is included within the definition of a transmission medium.

The information, signal, etc. described in the present disclosure may be represented using any of a variety of different technologies. For example, the data, the instruction, the commands, the information, the signal, the bit, the symbol, the chip, etc. may be represented by voltage, current, electromagnetic waves, magnetic field or magnetic particle, light field or photon, or any combination of these.

The terms described in the present disclosure and the terms necessary for understanding the present disclosure may be replaced with terms having the same or similar meanings. For example, at least one of the channel and the symbol may be a signal (signaling). The signal may also be a message. Further, the component carrier (CC) may be called a carrier frequency, a cell, a frequency carrier, and the like.

The terms “system” and “network” used in the present disclosure are used interchangeably.

Further, the information, parameters, etc. described in the present disclosure may be represented using an absolute value, may be represented by a relative value from a predetermined value, or may be represented by other corresponding information. For example, a radio resource may be indicated by an index.

The names used for the parameters mentioned above should not be limited in any respect. Further, mathematical formulas and the like using these parameters may differ from those explicitly disclosed in the present disclosure. Since various channels (for example, PUCCH, and PDCCH) and information elements can be identified by any suitable names, various names assigned to these various channels and information elements should net be limited in any respect.

The base station can accommodate one or more (for example, three) cells. When the base station accommodates a plurality of cells, the entire base station coverage area can be divided into a plurality of smaller areas, and each of the smaller areas can provide communication service by a base station subsystem (for example, a small indoor base station (RRH: Remote Radio Head)). The term “cell” or “sector” refers to a part or the whole of at least one of the coverage area of the base station and the base station subsystem that provides communication service in this coverage.

In the present disclosure, the terms “mobile station (MS)”, “user terminal”, “user equipment (UE)”, “terminal”, etc. may be used interchangeably.

At least one of the base station and the mobile station may be called a transmission device, a reception device, a communication device, and the like. At least one of the base station and the mobile station may be a device mounted on a movable body, the movable body itself and the like. The movable body may be a vehicle (for example, a car, and an airplane), may be an unmanned movable body (for example, a drone, and a self-driving car), or may be a robot (manned or unmanned). It should be noted that at least one of the base station and the mobile station includes a device that does not necessarily move during communication operation. For example, at least one of the base station and the mobile station may be IoT (Internet of Things) equipment such as a sensor.

Further, the base station in the present disclosure may be replaced by a user terminal. For example, each aspect/embodiment of the present disclosure may be applied to a configuration replaced by communication between a plurality of terminals20(for example, called D2D (Device-to-Device), and V2X (Vehicle-to-Everything)) for communication between the base station and the user terminal. In this case, the terminal20may have the function of the base station10described above. In addition, terms such as “upstream” and “downstream” may be replaced by terms corresponding to communication between terminals (for example, “side”). For example, an upstream channel, a downstream channel and the like may be replaced by a side channel.

Similarly, the user terminal in the present disclosure may be replaced by a base station. In this case, the base station may have the function of the user terminal described above.

A term “determining” used in the present disclosure may include a wide variety of operations. “Determining” may include “determining” judging, calculating, computing, processing, deriving, investigating, looking up, search, inquiry (for example, searching in a table, a database or another data structure) and ascertaining. “Determining” may include “determining” receiving (for example, receiving information), transmitting (for example, transmitting information), input, output and accessing (for example, accessing data in a memory). Further, “determining” may include “determining” resolving, selecting, choosing, establishing, comparing, etc. That is, “determining” may include “determining” a certain operation. Further, “determining” may be replaced by “assuming”, “expecting”, “considering”, and the like.

Terms “connected” and “coupled” or any variation thereof refer to any direct or indirect connection or coupling between two or more elements and may include the presence of one or more intermediate elements between the two “connected” or “coupled” elements each other. Connection or coupling between the elements may be physical, logical, or a combination thereof. For example, “connection” may be replaced by “access”. As used in the present disclosure, the two elements use at least one of one or more wires, cables and printed electrical connections, and as some non-limiting and non-comprehensive examples, and are considered to be “connected” or “coupled” to each other using electromagnetic energy having wavelengths in a radio frequency domain, a microwave domain and a light (both visible and invisible) domain.

The reference signal may be abbreviated as RS and may be called a pilot according to the applied standard.

“Based on” as used in the present disclosure does not mean “based only on” unless otherwise stated. In other words, the phrase “based on” means both “based only on” and “based at least on”.

Any reference to the elements using designations such as “first”, “second” and so on as used in the present disclosure does not generally limit the quantity or order of those elements. These designations may be used in the present disclosure as a convenient method to distinguish between two or more elements. Therefore, references to the first and second elements do not mean that only two elements can be adopted, or that the first element must somehow precede the second element.

The “means” in the configuration of each of the above devices may be replaced by a “part”, a “circuit”, a “device”, and the like.

When “include”, “including” and variations thereof are used in the present disclosure, these terms are intended to be inclusive as a term “comprising”. Further, the term “or” used in the present disclosure is intended not to be exclusive.

A radio frame may be configured by one or more frames in a time domain. Each frame of the one or more frames in the time domain may be called a subframe. The subframe may further be configured by one or more slots in the time domain. The subframe may be a fixed time length (for example, 1 ms) that does not depend on numerology.

The numerology may be a communication parameter that applies to at least one of transmission and reception of a signal or a channel. The numerology may indicate at least one of, for example, a subcarrier spacing (SCS), a bandwidth, a symbol length, a cyclic prefix length, a transmission time interval (TTI), a number of symbols per TTI, a wireless frame configuration, a specific windowing process performed by a transmitter/receiver to perform in a frequency domain, and a specific window wink process for the transmitter/receiver to perform in a time domain.

The slot may be configured by one or more symbols (OFDM (Orthogonal Frequency Division Multiplexing) symbol, and SC-FDMA (Single Carrier Frequency Division Multiple Access) symbol, etc.) in the time domain. The slot may be in time units based on numerology.

The slot may include a plurality of mini slots. Each mini slot may be configured by one or more symbols in the time domain. Further, the mini slot may be called a sub slot. The mini slot may be configured by a smaller number of symbols than the slots. PDSCH (or PUSCH) transmitted in the time unit larger than the mini slot may be called PDSCH (or PUSCH) mapping type A. PDSCH (or PUSCH) transmitted using the mini slot may be called PDSCH (or PUSCH) mapping type B.

The radio frame, the subframe, the slot, the mini slot and the symbol all represent in the time unit for transmitting a signal. For the radio frame, the subframe, the slot, the mini slot and the symbol, correspondingly different names may be used.

For example, one subframe may be called a transmission time interval (TTI), a plurality of consecutive subframes may be called TTI, and one slot or one mini slot may be called TTI. That is, at least one of the subframe and TTI may be a subframe (1 ms) in existing LTE, may be a period shorter than 1 ms (for example, 1-13 symbols), or may be a period longer than 1 ms. The unit representing TTI may be called a slot, a mini slot, and the like instead of the subframe.

Here, TTI refers to, for example, the minimum time unit of scheduling in wireless communication. For example, in the LTE system, the base station schedules each terminal20to allocate a wireless resource (a frequency bandwidth that can be used in each terminal20, transmission power, etc.) in a TTI unit. The definition of TTI is not limited to this.

TTI may be a transmission time unit such as a channel-encoded data packet (transport block), a code block, a code word, and the like, and may be a processing unit such as scheduling, link adaptation, and the like. When TTI is given, the time interval (for example, a number of symbols) to which the transport block, the code block, the code word, etc. is actually mapped may be shorter than the corresponding TTI.

When one slot or one mini slot is called TTI, one or more TTI (that is, one or more slots or one or more mini slots) may be the minimum time unit for scheduling. Further, a number of slots (a number of mini slots) configuring the minimum time unit of the corresponding scheduling may be controlled.

TTI having a time length of 1 ms may be called a usual TTI (TTI in LTE, Rel. 8-12), a normal TTI, a long TTI, a usual subframe, a normal subframe, a long subframe, a slot, and the like. A TTI shorter than the normal TTI may be called a shortened TTI, a short TTI, a partial TTI (a partial or fractional TTI), a shortened subframe, a short subframe, a mini slot, a subslot, a slot, and the like.

The long TTI (for example, a usual TTI and a subframe) may be replaced by a TTI having a time length of more than 1 ms, and the short TTI (for example, a shortened TTI) may be replaced by a TTI having a TTI length less than the TTI length of the long TTI and of 1 ms or more.

The resource block (RB) is a resource allocation unit in the time domain and the frequency domain and may include one or more continuous subcarriers in the frequency domain. A number of subcarriers included in RB may be the same regardless of numerology, for example, it may be 12. A number of subcarriers included in RB may be determined based on numerology.

The time domain of RB may also include one or more symbols and may be a length of one slot, one mini slot, one subframe, or one TTI. Each of one TTI, one subframe, etc. may be configured by one or more resource blocks.

One or more RBs may be called a physical resource block (PRB: Physical RB), a sub-carrier group (SCG), a resource element group (REG), a PRB pair, an RB pair, and the like.

Further, the resource block may be configured by one or more resource elements (REs). For example, one RE may be a wireless resource domain of one subcarrier and one symbol.

A bandwidth part (BWP) (which may also be called a partial bandwidth) may represent a subset of consecutive common RB (common resource blocks) for a certain neurology in a certain carrier. Here, the common RB may be specified by an index of RB with respect to a common reference point of the carrier. PRB may be defined in a certain BWP and may be numbered within the corresponding BWP.

The BWPs may include a BWP for UL (UL BWP) and a BWP for DL (DL BWP). One or more BWPs may be set in one carrier for the terminal20.

At least one of the set BWPs may be active and the terminal20may not be assumed to transmit/receive a predetermined signals/channel outside the active BWP. Further, the “cell”, “carrier”, etc. in the present disclosure may be replaced by “BWP”.

The configurations of the radio frame, the subframe, the slot, the mini slot, the symbol, and the like described above are merely examples. For example, configurations such as a number of subframes included in the radio frame, a number of slots per subframe or radio frame, a number of mini slots included in the slot, a number of symbols and RBs included in the slot or the mini slot, a number of subcarriers included in RB, a number of symbols in TTI, the symbol length, the cyclic prefix (CP) length can be changed in various ways.

In the present disclosure, if an article is added by translation, for example, a, an and the in English, the present disclosure may include plural nouns following these articles.

In the present disclosure, a term “A and B are different” may mean “A and B are different from each other”. The term may also mean “A and B are different from C”. Terms such as “separate”, “combine”, and the like may be similarly interpreted as “different”.

Each aspect/embodiment described in the present disclosure may be independently used, may be used in combination, or may be used by switching according to performance. Further, an indication of predetermined information (for example, an indication of “being X”) is not limited to an explicit one, and may be performed implicitly (for example, the indication of the predetermined information is not performed).

Note that, in the present disclosure, the first terminal is an example of the terminal20C. The second terminal is an example of the terminal20B.

Although the present disclosure has been described in detail above, it is clear to those skilled in the art that the present disclosure is not limited to the embodiments described in the present disclosure. The present disclosure may be implemented as amendment and modification aspects without departing from the spirit and scope of the present disclosure, which are determined by the description of the scope of claims. Therefore, description of the present disclosure is for purposes of illustration and does not have any limiting meaning to the present disclosure.

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