Terminal device method and terminal device

Abstract

To contribute to reducing reception failures of side-link control information for designating side-link transmission resources in each of a plurality of periods occurring at predetermined time intervals.SOLUTION: UE transmits a PSCCH including side-link control information used for PSSCH scheduling in a first time period, and transmits a PSSCH according to the side-link control information. The side-link control information includes a first information element and a second information element. The first information element indicates resource allocation for PSSCH transmission. Resources for the PSSCH transmission include a first frequency resource in the first time period. The second information element indicates whether the same frequency resource as the first frequency resource is still valid for the PSSCH transmission in a plurality of time periods occurring at predetermined time intervals after the first time period.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to device-to-device (D2D) communication, and more particularly to allocation of radio resources for D2D communication. [Background technology]

[0002] A form in which a wireless terminal communicates directly with another wireless terminal without going through an infrastructure network such as a base station is called device-to-device (D2D) communication. D2D communication includes at least one of direct communication and direct discovery. In some implementations, multiple wireless terminals supporting D2D communication form a D2D communication group autonomously or in response to instructions from a network, and communicate with other wireless terminals in the D2D communication group.

[0003] Proximity-based services (ProSe) specified in 3GPP (registered trademark) Release 12 is an example of D2D communication (see, for example, Non-Patent Document 1). ProSe Direct Discovery is performed by a procedure in which a radio terminal capable of executing ProSe (ProSe-enabled User Equipment (UE)) discovers another ProSe-enabled UE using only the capabilities of the radio communication technology (e.g., Evolved Universal Terrestrial Radio Access (E-UTRA) technology) that these two UEs possess. ProSe Direct Discovery may be performed by three or more ProSe-enabled UEs.

[0004] ProSe direct communication enables the establishment of a communication path between two or more ProSe-enabled UEs that are within a direct communication range after a ProSe direct discovery procedure. In other words, ProSe direct communication enables a ProSe-enabled UE to communicate directly with another ProSe-enabled UE without going through a Public Land Mobile Network (PLMN) including a base station (eNodeB (eNB)). ProSe direct communication may be performed using the same radio communication technology (E-UTRA technology) used to access the base station (eNB) or using a Wireless Local Area Network (WLAN) radio technology (i.e., IEEE 802.11 radio technology).

[0005] In 3GPP Release 12, the radio link between wireless terminals used for direct communication or direct discovery is called the sidelink (see, for example, Section 14 of Non-Patent Document 2). Sidelink transmissions use the same frame structure as the Long Term Evolution (LTE) frame structure defined for the uplink and downlink, and use a subset of uplink resources in the frequency and time domains. Wireless terminals (UEs) perform sidelink transmissions using Single Carrier Frequency Division Multiple Access (SC-FDMA), similar to the uplink.

[0006] In 3GPP Release 12 ProSe, the allocation of radio resources for sidelink transmission to a UE is performed by a radio access network (e.g., Evolved Universal Terrestrial Radio Access Network (E-UTRAN)). A UE that is authorized for sidelink communication by the ProSe function performs ProSe Direct Discovery or ProSe Direct Communication using the radio resources allocated by a radio access network node (e.g., eNB (eNB)).

[0007] For ProSe direct communication, two resource allocation modes are defined: scheduled resource allocation and autonomous resource selection. Scheduled resource allocation and autonomous resource selection are called "sidelink transmission mode 1" and "sidelink transmission mode 2", respectively (see section 14 of non-patent document 2).

[0008] In scheduled resource allocation for ProSe direct communication, when a UE desires sidelink transmission, it requests radio resource allocation for sidelink transmission from the eNB, and the eNB allocates resources for sidelink control and data to the UE. Specifically, the UE sends a scheduling request to the eNB to request uplink (UL) data transmission resources (Uplink Shared Channel (UL-SCH) resources) and transmits a Sidelink Buffer Status Report (Sidelink BSR) to the eNB in ​​the UL data transmission resources allocated in the uplink grant (UL grant). The eNB determines the sidelink transmission resources to allocate to the UE based on the Sidelink BSR and transmits a Sidelink grant (SL grant) to the UE.

[0009] The SL grant is defined as Downlink Control Information (DCI) format 5. The SL grant (DCI format 5) includes the following content: Resource for PSCCH, Resource block assignment and hopping allocation, and Time resource pattern index. Resource for PSCCH indicates the radio resource for the sidelink control channel (i.e., Physical Sidelink Control Channel (PSCCH)). Resource block assignment and hopping allocation are used to determine the frequency resource, i.e., the set of subcarriers (resource blocks), for transmitting the sidelink data channel (i.e., Physical Sidelink Shared Channel (PSSCH)) for sidelink data transmission. Time resource pattern index is used to determine the time resource, i.e., the set of subframes, for transmitting the PSSCH. Strictly speaking, a resource block refers to a time-frequency resource in LTE and LTE-Advanced and is a resource unit defined by multiple consecutive OFDM (or SC-FDMA) symbols in the time domain and multiple consecutive subcarriers in the frequency domain. In the case of a normal cyclic prefix, one resource block includes 12 consecutive OFDM (or SC-FDMA) symbols in the time domain and 12 subcarriers in the frequency domain. That is, the resource block assignment and hopping allocation and the time resource pattern index specify the resource block for transmitting the PSSCH. The UE (i.e., the sidelink transmitting terminal) determines the PSCCH resource and the PSSCH resource according to the SL grant.

[0010] On the other hand, in autonomous resource selection for ProSe direct communication, the UE autonomously selects resources for sidelink control (PSCCH) and data (PSSCH) from a resource pool configured by the eNB. The eNB may assign a resource pool to the UE for use in autonomous resource selection in System Information Block (SIB) 18. Note that the eNB may also assign a resource pool for use in autonomous resource selection to a UE in Radio Resource Control (RRC)_CONNECTED by dedicated RRC signaling. This resource pool may also be available when the UE is in RRC_IDLE.

[0011] When performing direct transmission in the sidelink, the transmitting UE (D2D transmitting UE) (hereinafter referred to as the transmitting terminal) transmits scheduling assignment information (Scheduling Assignment) using a radio resource area (resource pool) for the sidelink control channel (i.e., PSCCH). The scheduling assignment information is also called Sidelink Control Information (SCI) format 0. The scheduling assignment information includes content such as resource block assignment and hopping allocation, time resource pattern index, and Modulation and Coding Scheme (MCS). In the case of the above-mentioned scheduled resource allocation, the resource block assignment and hopping allocation and time resource pattern index indicated by the Scheduling Assignment (SCI format 0) follow the resource block assignment and hopping allocation and time resource pattern index indicated by the SL grant (DCI format 5) received from the eNB.

[0012] The transmitting terminal transmits data on the PSSCH using radio resources according to the scheduling allocation information. The receiving side UE (D2D receiving UE) (hereinafter referred to as receiving terminal) receives the scheduling allocation information from the transmitting terminal on the PSCCH, and receives data on the PSSCH according to the scheduling allocation information. Note that the term transmitting terminal here is an expression focusing on the transmission operation of the radio terminal, and does not mean a radio terminal dedicated to transmission. Similarly, the term receiving terminal is an expression focusing on the reception operation of the radio terminal, and does not mean a terminal dedicated to reception. In other words, the transmitting terminal can also perform reception operation, and the receiving terminal can also perform transmission operation.

[0013] The following describes a sidelink control period, a resource pool for the PSCCH, and a resource pool for the PSSCH. These are necessary for determining radio resources (i.e., subframes and resource blocks) for transmitting the PSCCH and radio resources for transmitting the PSSCH. As already described, the PSCCH is a sidelink physical channel used for transmitting sidelink control information (SCI) such as scheduling assignment information. On the other hand, the PSSCH is a sidelink physical channel used for user data transmission (direct transmission).

[0014] The sidelink control period is a scheduling cycle for the sidelink (see Figure 1). The sidelink control period is also called the PSCCH period. The transmitting terminal transmits scheduling assignment information (i.e., SCI format 0) during each sidelink control period. In 3GPP Release 12, the sidelink control period is 40 ms, 60 ms, 70 ms, 80 ms, 120 ms, 140 ms, 160 ms, 240 ms, 280 ms, or 320 ms. In other words, the sidelink control period is 40 subframes, 60 subframes, 70 subframes, 80 subframes, 120 subframes, 140 subframes, 160 subframes, 240 subframes, 280 subframes, or 320 subframes.

[0015] Therefore, the transmitting terminal notifies the receiving terminal of the allocation of PSSCH resources every sidelink control period, i.e., every 40 ms or more. However, the allocation of PSSCH resources is specified in units of 6, 7, or 8 subframes (6, 7, or 8 ms) using a time resource pattern index. Therefore, the same PSSCH resource allocation is used every 6, 7, or 8 subframes during one sidelink control period.

[0016] In one sidelink control period, the transmitting terminal selects L included in the resource pool (subframe pool) for the PSCCH. PSCCH The scheduling assignment information (i.e., SCI format 0) is transmitted twice in two subframes out of the total number of subframes. These two transmissions are performed using M subframes included in the resource pool (resource block pool) for the PSCCH. PSCCH_RP RB The transmission is performed in two different resource blocks among the resource blocks.

[0017] The resource pool for the PSCCH is configured to the UE by the eNB via broadcast (SIB 18) or dedicated signaling (RRC signaling). The resource pool for the PSCCH is configured to the UE via broadcast (SIB 18) or dedicated signaling (RRC signaling). PSCCH subframes and M PSCCH_RP RB It consists of frequency domain resource blocks.

[0018] The method for specifying a resource pool for the PSCCH will be explained using Figures 2 and 3. The resource pool for the PSCCH consists of a subframe pool and a resource block pool. Figure 2 shows the subframe pool for the PSCCH, and Figure 3 shows the resource block pool for the PSCCH.

[0019] To identify the subframe pool for the PSCCH, the eNB specifies the length (P) of the sidelink control period (PSCCH period) and the subframe bitmap and its length (N') for the PSCCH. The length (N') of the subframe bitmap can be 4, 8, 12, 16, 30, 40, or 42 bits. The N' subframes corresponding to the subframe bitmap are the first N' subframes in the sidelink control period, as shown in Figure 2. The subframe bitmap indicates that subframes corresponding to bits set to "0" are not used for PSCCH transmission, and that subframes corresponding to bits set to "1" can be used for PSCCH transmission. Therefore, the number of subframes (L) included in the PSCCH resource pool within one sidelink control period is PSCCH ) is equal to the number of subframes that have a value of 1 in the subframe bitmap. The subframes included in the PSCCH resource pool (i.e., the subframe pool) can be expressed as follows:

number

[0020] Meanwhile, as shown in Figure 3, the eNB specifies a start physical resource block (PRB) index (S1), an end PRB index (S2), and the number of PRBs (M) to identify a resource block pool for the PSCCH. The resource block pool includes M PRBs whose PRB index q is greater than or equal to the start index (S1) and less than S1 + M (S1 <= q < S1 + M), and M PRBs whose PRB index q is greater than S2 - M and less than or equal to the end index (S2) (S2 - M < q <= S2) (i.e., a total of 2M PRBs). That is, the eNB can include two PRB clusters, each containing M PRBs, in the resource block pool for the PSCCH.

[0021] Next, we will explain how to specify a resource pool for the PSSCH. In the case of scheduled resource allocation (sidelink transmission mode 1), the eNB specifies a subframe pool for the PSSCH in SIB 18 or dedicated signaling (RRC signaling). The sidelink control period (PSCCH period) associated with the PSCCH resource configuration is further associated with the PSSCH resource configuration. The UE determines the PSSCH resource pool consisting of the subframe pool as follows: That is, as shown in Figure 2, within the sidelink control period (PSCCH period), PSCCH PSCCH-1 Every subframe with a subframe index greater than or equal to +1 belongs to the subframe pool for the PSSCH.

[0022] On the other hand, in the case of autonomous resource selection (sidelink transmission mode 2), the eNB specifies the subframe pool and resource block pool for the PSSCH in SIB 18 or dedicated signaling (RRC signaling). To specify the subframe pool, the eNB specifies the offset (O2), as well as the subframe bitmap and its length (N B ) is specified.

[0023] The offset (O2) is the subframe index j of the first subframe of the sidelink control period (PSCCH period). begin Here, j within the PSCCH period indicates the offset from begin + Let N' be the total number of subframes with subframe index greater than or equal to O2.

[0024] Subframe bitmap length (N B) is 4, 8, 12, 16, 30, 40, or 42 bits. The subframe bitmap indicates that the subframes corresponding to bits set to "0" are not used for PSSCH transmission, and that the subframes corresponding to bits set to "1" can be used for PSSCH transmission. Note that the length of the subframe bitmap (N B ) is j during the PSCCH period. begin + the total number of subframes (N') with subframe indexes equal to or greater than O2. Therefore, the UE uses the bitmap b0, b1, b2, ..., b N’-1 is determined according to the following formula:

number

[0025] The resource block pool for the PSSCH in case of autonomous resource selection (sidelink transmission mode 2) is specified in the same way as the resource block pool for the PSCCH: the eNB specifies the start Physical Resource Block (PRB) index (S1), the end PRB index (S2), and the number of PRBs (M) in the PSSCH resource configuration to identify the resource block pool for the PSSCH. [Prior art documents] [Non-patent literature]

[0026] [Non-Patent Document 1] 3GPP TS 23.303 V12.4.0 (2015-03), “3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; Proximity-based services (ProSe); Stage 2 (Release 12)”, March 2015 [Non-patent document 2] 3GPP TS 36.213 V12.5.0 (2015-03), “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures (Release 12)”, March 2015 Summary of the Invention [Problem to be solved by the invention]

[0027] As mentioned above, sidelink transmission in 3GPP Release 12 uses a subset of uplink resources in the frequency and time domains. Therefore, a UE cannot receive sidelink signals transmitted by other UEs in the same subframe during sidelink transmission, because the UE's own signals would be received as high-power interference.

[0028] Therefore, in a subframe in which a UE transmits scheduling assignment information (i.e., SCI format 0) on the PSCCH, the UE cannot receive scheduling assignment information (SCI format 0) transmitted from another UE. If the UE fails to receive scheduling assignment information in a certain sidelink control period (PSCCH period), data reception (PSSCH reception) associated with the scheduling assignment information also fails in the sidelink control period. Note that the number of subframes included in the radio resource region for the PSCCH (subframe pool for the PSCCH) in which the scheduling assignment information is transmitted is smaller than the number of subframes included in the radio resource region for data transmission (PSSCH transmission) (subframe pool for the PSSCH). For this reason, a situation in which a UE cannot receive scheduling assignment information from another UE because it is transmitting scheduling assignment information (i.e., SCI format 0) on the PSCCH is likely to occur.

[0029] One of the objectives to be achieved by the embodiments disclosed in this specification is to provide an apparatus, a method, and a program that contribute to reducing failures in reception of scheduling assignment information (e.g., SCI format 0) that is transmitted in a control radio resource region (e.g., a resource pool for PSCCH) within a periodic D2D control period (e.g., a sidelink control period) and specifies D2D transmission resources (e.g., subframes and resource blocks for PSSCH transmission). [Means for solving the problem]

[0030] In a first aspect, a transmitting terminal includes at least one wireless transceiver and at least one processor, coupled to the at least one wireless transceiver and configured to transmit data to other wireless terminals without going through a base station according to periodic device-to-device (D2D) control periods. Each D2D control period includes a first subframe pool of subframes usable for transmitting D2D control information and a second subframe pool of subframes usable for the data transmission in accordance with the D2D control information. The at least one processor is configured to transmit first D2D control information in one or more subframes in the first subframe pool during a first D2D control period and to transmit the data in accordance with the first D2D control information in one or more subframes in the second subframe pool during the first D2D control period, the first D2D control information including a first information element for identifying one or more subframes in the second subframe pool during the first D2D control period. The first D2D control information further includes a second information element indicating whether the first D2D control information is valid in at least one D2D control period after the first D2D control period.

[0031] In a second aspect, a method in a transmitting terminal includes transmitting data to a receiving terminal without going through a base station according to periodic device-to-device (D2D) control periods. Each D2D control period includes a first subframe pool of subframes usable for transmission of D2D control information and a second subframe pool of subframes usable for the data transmission in accordance with the D2D control information. The performing the D2D transmission includes transmitting first D2D control information in one or more subframes in the first subframe pool within a first D2D control period and performing the data transmission in accordance with the first D2D control information in one or more subframes in the second subframe pool within the first D2D control period. The first D2D control information includes a first information element for identifying one or more subframes in the second subframe pool within the first D2D control period. The first D2D control information further includes a second information element indicating whether the first D2D control information is valid in at least one D2D control period after the first D2D control period.

[0032] In a third aspect, a receiving terminal includes at least one wireless transceiver and at least one processor. The at least one processor is coupled to the at least one wireless transceiver and configured to receive data from a transmitting terminal without going through a base station according to periodic device-to-device (D2D) control periods. Each D2D control period includes a first subframe pool of subframes usable for transmitting D2D control information and a second subframe pool of subframes usable for receiving the data in accordance with the D2D control information. The at least one processor is configured to receive first D2D control information in one or more subframes in the first subframe pool during a first D2D control period, and to receive the data in one or more subframes in the second subframe pool during the first D2D control period according to the first D2D control information. The first D2D control information includes a first information element for identifying one or more subframes in the second subframe pool during the first D2D control period. The first D2D control information further includes a second information element indicating whether the first D2D control information is valid in at least one D2D control period after the first D2D control period.

[0033] In a fourth aspect, a method in a receiving terminal includes receiving data from a transmitting terminal without going through a base station according to periodic device-to-device (D2D) control periods. Each D2D control period includes a first subframe pool of subframes usable for transmitting D2D control information and a second subframe pool of subframes usable for receiving the data in accordance with the D2D control information. The performing the data reception includes receiving first D2D control information in one or more subframes in the first subframe pool within a first D2D control period and performing the data reception in one or more subframes in the second subframe pool within the first D2D control period in accordance with the first D2D control information. The first D2D control information includes a first information element for identifying one or more subframes in the second subframe pool within the first D2D control period. The first D2D control information further includes a second information element indicating whether the first D2D control information is valid in at least one D2D control period after the first D2D control period.

[0034] In a fifth aspect, a base station includes a radio transceiver configured to communicate with a plurality of radio terminals within a cell and at least one processor configured to control data transmission from a first radio terminal to a second radio terminal according to periodic device-to-device (D2D) control periods without going through the base station. Each D2D control period includes a first subframe pool of subframes usable for transmission of D2D control information and a second subframe pool of subframes usable for the data transmission according to the D2D control information. The at least one processor is configured to transmit a D2D grant message to the first radio terminal indicating a radio resource allocation for transmission of the D2D control information and the data transmission during the first D2D control period, and indicating that the radio resource allocation is valid for at least one D2D control period after the first D2D control period.

[0035] In a sixth aspect, a method in a base station includes controlling data transmissions from a first wireless terminal to a second wireless terminal according to periodic device-to-device (D2D) control periods, each D2D control period including a first subframe pool of subframes usable for transmission of D2D control information and a second subframe pool of subframes usable for the data transmission according to the D2D control information. The controlling includes transmitting a D2D grant message to the first wireless terminal indicating radio resource allocations for the transmission of the D2D control information and the data transmissions within the first D2D control period, and indicating that the radio resource allocations are valid for at least one D2D control period after the first D2D control period.

[0036] In a seventh aspect, a program includes a group of instructions (software code) that, when loaded into a computer, causes the computer to perform the method according to the second, fourth or sixth aspect above. [Effects of the Invention]

[0037] According to the above-described aspects, it is possible to provide an apparatus, a method, and a program that contribute to reducing failures in reception of scheduling assignment information (e.g., SCI format 0) that is transmitted in a control radio resource region (e.g., a resource pool for PSCCH) within a periodic D2D control period (e.g., a sidelink control period) and specifies D2D transmission resources (e.g., subframes and resource blocks for PSSCH transmission). [Brief explanation of the drawings]

[0038] [Figure 1] FIG. 1 is a diagram illustrating a sidelink control period (PSCCH period). [Figure 2] FIG. 10 is a diagram illustrating an example of a PSCCH subframe pool and a PSSCH subframe pool within a sidelink control period. [Figure 3] FIG. 10 illustrates an example of a PSCCH resource block pool within a sidelink control period. [Figure 4] 1 is a diagram illustrating an example configuration of a wireless communication system according to some embodiments. [Figure 5] FIG. 2 is a diagram for explaining transmission of scheduling assignment information (PSCCH) and data (PSSCH) on a side link by a radio terminal (transmitting terminal) according to the first embodiment. [Figure 6] 5 is a flowchart showing an example of the operation of a wireless terminal (transmitting terminal) according to the first embodiment. [Figure 7] 5 is a flowchart showing an example of the operation of the wireless terminal (receiving terminal) according to the first embodiment. [Figure 8] 6 is a flowchart showing an example of an operation of the base station according to the first embodiment. [Figure 9] 10 is a flowchart showing an example of the operation of a wireless terminal (transmitting terminal) according to the second embodiment. [Figure 10] 10 is a flowchart showing an example of the operation of a wireless terminal (receiving terminal) according to the second embodiment. [Figure 11] 10 is a flowchart showing an example of the operation of a wireless terminal (transmitting terminal) according to the third embodiment. [Figure 12] 10 is a flowchart showing an example of an operation of a base station according to the fourth embodiment. [Figure 13] FIG. 1 is a block diagram illustrating an example configuration of a wireless terminal according to some embodiments. [Figure 14] FIG. 1 is a block diagram illustrating an example configuration of a base station according to some embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0039] Hereinafter, specific embodiments will be described in detail with reference to the drawings. In each drawing, the same or corresponding elements are designated by the same reference numerals, and for clarity of explanation, duplicate explanations will be omitted as necessary.

[0040] The following embodiments will be described mainly targeting improvements to ProSe defined in 3GPP Release 12 (LTE-Advanced). However, these embodiments are not limited to LTE-Advanced and its improvements, and may be applied to D2D communication in other mobile communication networks or systems.

[0041] First Embodiment FIG. 4 illustrates a configuration example of a wireless communication system according to some embodiments, including this embodiment. Each of wireless terminals (UE) 1A and 1B has at least one wireless transceiver and is configured to perform cellular communication (101 or 102) with a base station (eNB) 2 and to perform D2D communication over a device-to-device direct interface (e.g., PC5 interface or sidelink) 103. The D2D communication includes at least direct communication (ProSe Direct Communication) and may further include direct discovery (e.g., ProSe Direct Discovery). The eNB 2 manages a cell 21 and can perform cellular communication (101 and 102) with each of multiple UEs 1 using cellular communication technology (e.g., Evolved Universal Terrestrial Radio Access (E-UTRA) technology). Note that, for the sake of simplicity, the example of FIG. 5 illustrates a situation in which multiple UEs 1A and 1B are located within the same cell 21, but this arrangement is merely an example. For example, UE1A may be located in one cell and UE1B in the other cell of two adjacent cells managed by different eNB2s, or at least one of UE1A and UE1B may be located outside the coverage of one or more eNB2s.

[0042] Next, the transmission of PSCCH and PSSCH in the sidelink according to this embodiment will be described below. A transmitting terminal (e.g., UE1A) is configured to transmit data to another radio terminal (receiving terminal (e.g., UE1B)) without going through eNB2 in accordance with a periodic D2D control period (i.e., sidelink control period (PSCCH period)). As already described, the sidelink control period includes a subframe pool for PSCCH (first subframe pool) and a subframe pool for PSSCH (second subframe pool). The subframe pool for PSCCH includes L subframes available for transmitting sidelink control information (SCI) including scheduling assignment information (i.e., SCI format 0).PSCCH On the other hand, the subframe pool for PSSCH consists of L subframes that can be used for data transmission (PSSCH transmission) according to the scheduling assignment information (i.e., SCI format 0). PSSCH It consists of subframes.

[0043] More specifically, a transmitting terminal (e.g., UE1A) transmits sidelink control information (D2D control information) in one or more subframes (e.g., two subframes) in a PSCCH subframe pool within the jth sidelink control period. Furthermore, the transmitting terminal (e.g., UE1A) transmits data (PSSCH transmission) in one or more subframes in the PSSCH subframe pool within the jth sidelink control period in accordance with the sidelink control information. The sidelink control information transmitted in the jth sidelink control period includes a first information element (e.g., Scheduling Assignment Information (SCI) format 0) for identifying one or more subframes in the PSSCH subframe pool within the jth sidelink control period. Additionally, the sidelink control information transmitted in the jth sidelink control period includes a second information element indicating whether the radio resource allocation for the data transmission (PSSCH transmission) according to the sidelink control information remains valid in at least one sidelink control period after the (j+1)th sidelink control period.

[0044] The transmitting terminal (e.g., UE1A) may be configured to transmit data on the PSSCH without transmitting new sidelink control information (scheduling assignment information (SCI format 0)) in at least one sidelink control period from the (j+1)th onward in which the radio resource allocation for data transmission in the jth sidelink control period remains valid. On the other hand, the receiving terminal (e.g., UE1B) may be configured to receive data on the PSSCH without receiving new sidelink control information (scheduling assignment information) in at least one sidelink control period from the (j+1)th onward in which the radio resource allocation for data transmission in the jth sidelink control period remains valid.

[0045] This reduces the probability that the transmitting terminal fails to receive sidelink control information from other UEs in at least one sidelink control period after the (j+1)th period. Furthermore, the PSCCH transmission according to this embodiment reduces the number of PSCCH transmissions compared to the case where sidelink control information (scheduling assignment information) is transmitted every sidelink control period. Therefore, it reduces the probability of collisions occurring when multiple PSCCH transmissions from multiple sidelink transmitting terminals that are close to each other are performed using the same radio resources.

[0046] In some implementations, the second information element may specify the length of at least one SLCI period after the (j+1)th SLCI period (i.e., at least one SLCI period during which the radio resource allocation for data transmission in the jth SLCI period remains valid). For example, the second information element may indicate the number of SLCI periods during which the SLCI information (Scheduling Assignment Information (SCI format 0)) transmitted in the jth SLCI period remains valid.

[0047] The transmitting terminal may autonomously determine the number of sidelink control periods during which radio resource allocation for data transmission in the j-th sidelink control period remains valid (referred to as the number of effective sidelink control periods). Alternatively, the transmitting terminal may have the number of effective sidelink control periods for radio resource allocation configured by the eNB2. For example, in the case of scheduled resource allocation (sidelink transmission mode 1), the eNB2 may notify the transmitting terminal of the number of effective sidelink control periods for radio resource allocation in a sidelink scheduling grant (DCI format 5). In the case of autonomous resource selection (sidelink transmission mode 2), the eNB2 may notify the transmitting terminal of the number of effective sidelink control periods for radio resource allocation in SIB 18 or PSCCH resource configuration or PSSCH resource configuration via RRC signaling.

[0048] For example, the transmitting terminal may determine the number of effective sidelink control periods for radio resource allocation according to the amount of data to be transmitted in the sidelink stored in the data buffer. That is, the transmitting terminal may determine the number of effective sidelink control periods corresponding to the PSSCH resources required to transmit the untransmitted data. This allows the number of transmissions of sidelink control information (Scheduling Assignment Information (SCI format 0)) on the PSCCH to be appropriately reduced.

[0049] For example, the transmitting terminal may determine the number of valid sidelink control periods for radio resource allocation according to the delay requirement of an application (application program). Here, the delay requirement may be at least one of maximum delay, average delay, and priority regarding delay guarantee. If the application requires strict delay requirements (i.e., low delay), the transmitting terminal may increase the number of valid sidelink control periods compared to other applications. This prevents failures in receiving sidelink control information and the associated data transmission failures for a long period of time, thereby contributing to achieving the strict delay requirement (i.e., low delay) required by the application.

[0050] For example, the transmitting terminal may be configured by the eNB2 with the number of valid sidelink control periods according to the number of sidelink transmissions or the number of sidelink transmitting terminals in the cell 21. For example, the eNB2 may increase the number of valid sidelink control periods as the number of sidelink transmissions (the number of sidelink transmitting terminals) in the cell 21 increases. This reduces the number of PSCCH transmissions when the number of sidelink transmissions (the number of sidelink transmitting terminals) in the cell 21 is large. This reduces the probability of collisions occurring when multiple PSCCH transmissions from multiple sidelink transmitting terminals that are close to each other use the same radio resources.

[0051] Alternatively, in some implementations, the second information element may indicate whether radio resource allocation for data transmission in the jth sidelink control period is continued. The second information element may be flag information indicating whether radio resource allocation is continued. For example, the second information element may be 1-bit flag information. If the flag value is “1”, the radio resource allocation for data transmission in the jth sidelink control period may be valid for the (j+1)th and subsequent sidelink control periods. On the other hand, if the flag value is “0”, the radio resource allocation for data transmission in the jth sidelink control period may be valid only for the jth sidelink control period.

[0052] Fig. 5 shows an example of transmission of PSCCH and PSSCH according to this embodiment. In the example of Fig. 5, a transmitting terminal (e.g., UE1A) transmits sidelink control information on the PSCCH in two subframes (522 and 523) in a PSCCH subframe pool 511 during a j-th sidelink control period (PSCCH period) 501. The sidelink control information 522 and 523 transmitted during the j-th sidelink control period 501 not only includes scheduling assignment information (i.e., SCI format 0) but also indicates that the scheduling assignment information is valid for the (j+1)-th sidelink control period 502 and thereafter.

[0053] A transmitting terminal (e.g., UE 1A) performs data transmissions (PSSCH transmissions) 531-534 in a plurality of subframes in a PSSCH subframe pool 512 in a j-th sidelink control period 501 in accordance with the sidelink control information 522 and 523. Furthermore, the transmitting terminal (e.g., UE 1A) performs data transmissions (PSSCH transmissions) 535-538 in a PSSCH subframe pool 514 in the sidelink control period 502 without transmitting sidelink control information in a PSCCH subframe pool 513 in a (j+1)-th sidelink control period 502. The data transmissions (PSSCH transmissions) 535-538 are in accordance with the sidelink control information 522 and 523 transmitted in the j-th sidelink control period 501. Similarly, the transmitting terminal (e.g., UE 1A) does not transmit sidelink control information in the PSCCH subframe pool 515 in the (j+2)th sidelink control period 503, but performs data transmissions (PSSCH transmissions) 539-542 in the PSSCH subframe pool 516 in the sidelink control period 503. The data transmissions (PSSCH transmissions) 539-542 follow the sidelink control information 522 and 523 transmitted in the jth sidelink control period 501.

[0054] 6 is a flowchart showing an example (process 600) of the operation of a transmitting terminal (e.g., UE1A) according to the present embodiment. In block 601, the transmitting terminal transmits, to a receiving terminal (e.g., UE1B), sidelink control information (SCI) indicating PSSCH resources and availability of PSSCH resource allocation from the (j+1)th sidelink control period (PSCCH period) onwards during the jth sidelink control period (PSCCH period). In block 602, the transmitting terminal transmits data on the PSSCH during the jth sidelink control period (PSCCH period) in accordance with the sidelink control information for the jth sidelink control period.

[0055] In block 603, the transmitting terminal determines whether there is pending data in the buffer to be transmitted on the sidelink. If there is pending data in the buffer (YES in block 603), the transmitting terminal determines whether there is a valid scheduling assignment for the receiving terminal of the pending data (block 604). If there is a valid scheduling assignment (YES in block 604), the transmitting terminal transmits data on the PSSCH in the (j+1)th or subsequent sidelink control period according to the sidelink control information for the jth sidelink control period (PSCCH period). On the other hand, if there is no valid scheduling assignment (NO in block 604), the transmitting terminal returns to block 601 and transmits new sidelink control information (scheduling assignment information (SCI format 0)).

[0056] 7 is a flowchart showing an example (process 700) of the operation of a receiving terminal (e.g., UE 1B) according to the present embodiment. In block 701, the receiving terminal receives, from a transmitting terminal (e.g., UE 1A), sidelink control information (SCI) indicating PSSCH resources and availability of PSSCH resource allocation from the (j+1)th sidelink control period (PSCCH period) onwards during the jth sidelink control period (PSCCH period). In block 702, the receiving terminal receives data on the PSSCH during the jth sidelink control period (PSCCH period) in accordance with the sidelink control information for the jth sidelink control period.

[0057] In block 703, the receiving terminal determines whether it has a valid scheduling assignment. If so (YES in block 703), the receiving terminal receives data on the PSSCH in the (j+1)th or subsequent sidelink control period according to the sidelink control information for the jth sidelink control period (PSCCH period).

[0058] FIG. 8 is a flowchart showing an example of the operation of the eNB2 (process 700) according to this embodiment. As already explained, the transmitting terminal may be configured by the eNB2 with the number of valid sidelink control periods for radio resource allocation. FIG. 8 illustrates the case of scheduled resource allocation (sidelink transmission mode 1). In block 801, the eNB2 determines the number of valid sidelink control periods for radio resource allocation for sidelink transmission. In block 802, the eNB2 transmits a sidelink scheduling grant to UE1 (the transmitting terminal) indicating that sidelink transmission is permitted in multiple sidelink control periods (PSCCH periods). That is, the sidelink scheduling grant indicates a PSCCH transmission resource allocation, a PSSCH transmission resource allocation, and the number of sidelink control periods for which the PSSCH transmission resource allocation is valid.

[0059] <Second embodiment> In this embodiment, a modification of the sidelink transmission described in the first embodiment is described. An example of the configuration of the wireless communication system according to this embodiment is the same as that shown in Fig. 4. In this embodiment, a procedure for deactivating (or canceling) PSSCH resource allocation across multiple sidelink control periods is described.

[0060] In some implementations, a transmitting terminal (e.g., UE 1A) may be configured to transmit, to a receiving terminal (e.g., UE 1B) in any of the (j+1)-th or subsequent sidelink control periods, sidelink control information indicating that a radio resource allocation for a (j+1)-th or subsequent data transmission (PSSCH transmission) based on sidelink control information (scheduling assignment information) in the j-th sidelink control period is disabled. In other words, to disable (or cancel) a PSSCH scheduling assignment (SCI format 0) in the j-th sidelink control period that has been enabled for multiple sidelink control periods, the transmitting terminal may transmit, in any of the (j+1)-th or subsequent sidelink control periods, sidelink control information indicating the deactivation (cancellation) of the scheduling assignment.

[0061] The sidelink control information indicating the invalidation (cancellation) of a scheduling assignment may use a reserved value of the validity duration of the scheduling assignment (e.g., a value of 11111111 in the case of 8 bits). Alternatively, the sidelink control information indicating the invalidation (cancellation) of a scheduling assignment may include a flag indicating the invalidation of the scheduling assignment.

[0062] Note that multiple scheduling assignments may be valid between the transmitting terminal and the receiving terminal. In this case, the receiving terminal may invalidate all valid scheduling assignments based on information indicating invalidation (cancellation) from the transmitting terminal. Alternatively, the transmitting terminal may transmit to the receiving terminal an identifier indicating a scheduling assignment to be invalidated among the multiple valid scheduling assignments.

[0063] Additionally or alternatively, in some implementations, the receiving terminal (e.g., UE1B) may autonomously disable (or cancel) a scheduling assignment that has been enabled for multiple sidelink control periods. For example, the receiving terminal (e.g., UE1B) may disable a scheduling assignment (i.e., a PSSCH resource assignment) that has been enabled in the j-th sidelink control period if no data is received on the PSSCH from the transmitting terminal (e.g., UE1A) for a predetermined period in the (j+1)-th or subsequent sidelink control period.

[0064] When a scheduling assignment (i.e., PSSCH resource assignment) is enabled over multiple sidelink control periods, the receiving terminal may attempt to receive the PSSCH in each sidelink control period within the enabled sidelink control period, even though no data transmission on the PSSCH occurs in the (j+1)th or subsequent sidelink control periods because there is no data to be transmitted in the buffer of the transmitting terminal (i.e., sidelink transmission has been completed). Such unnecessary reception operations may result in unnecessary power consumption and reduced transmission opportunities in the receiving terminal. The procedure for disabling the scheduling assignment described in this embodiment can mitigate such adverse effects.

[0065] 9 is a flowchart illustrating an example of the operation (process 900) of a transmitting terminal according to the present embodiment. In block 901, the transmitting terminal determines that data transmission has been completed while PSSCH resource allocation for multiple sidelink control periods (PSCCH periods) is valid. In block 902, the transmitting terminal transmits sidelink control information to the receiving terminal indicating that PSSCH resource allocation for multiple sidelink control periods (PSCCH periods) is disabled.

[0066] 10 is a flowchart showing an example of the operation (process 1000) of a receiving terminal according to this embodiment. In block 1001, the receiving terminal detects that no data reception occurs on the PSSCH from the transmitting terminal for a predetermined period while a PSSCH resource allocation for multiple sidelink control periods (PSCCH periods) is valid. In block 1002, the receiving terminal autonomously disables the PSSCH resource allocation for multiple sidelink control periods (PSCCH periods).

[0067] <Third embodiment> In this embodiment, a modification of the sidelink transmission described in the first embodiment is described. A configuration example of a wireless communication system according to this embodiment is the same as that shown in FIG. 4. In this embodiment, a transmitting terminal (e.g., UE1A) is configured to set a restriction on PSSCH resource allocation over multiple sidelink control periods for the transmitting terminal autonomously or in accordance with an instruction from eNB2. In this embodiment, an example is shown in which a restriction is set individually for a specific UE1 or a specific UE group in a cell 21.

[0068] In some implementations, a transmitting terminal may autonomously or following instructions from the eNB2 impose a restriction on PSSCH resource allocation across multiple sidelink control periods when the transmitting terminal is estimated to be located at the cell boundary between the cell 21 (i.e., the serving cell) of the eNB2 and a neighboring cell. In this case, the restriction may be to not allow continuous activation of PSSCH resource allocation across multiple sidelink control periods. Alternatively, the restriction may be to set an upper limit on the number of sidelink control periods during which PSSCH resource allocation is enabled (number of active sidelink control periods).

[0069] The transmitting terminal being located at the cell boundary may be determined based on any one or any combination of the following conditions (a) to (d): (a) The reception quality (Reference Signal Received Power (RSRP) or Reference Signal Received Quality (RSRQ)) of the downlink signal of the serving cell 21 is equal to or less than a predetermined value; (b) The reception quality of the downlink signal of the neighboring cell is equal to or greater than a predetermined value; (c) The distance of the serving cell 21 from the eNB2 is equal to or greater than a predetermined value; and (d) The distance from the neighboring cell's eNB is less than a predetermined value.

[0070] If the transmitting terminal is estimated to be located at the cell boundary between cell 21 of eNB2 (i.e., the serving cell) and an adjacent cell, the transmitting terminal may cause interference to UEs or eNBs of the adjacent cell. Therefore, in other words, if there is a risk of causing interference to UEs or eNBs of the adjacent cell, the transmitting terminal may set a restriction on PSSCH resource allocation across multiple sidelink control periods to the transmitting terminal autonomously or in accordance with an instruction from eNB2.

[0071] 11 is a flowchart showing an example of the operation (process 1100) of a transmitting terminal according to this embodiment. In block 1101, the transmitting terminal detects that it is located at a cell boundary. In block 1102, the transmitting terminal sets a limit on PSSCH resource allocation for multiple sidelink control periods (PSCCH periods).

[0072] In this embodiment, a limit on PSSCH resource allocation over multiple sidelink control periods can be set for a transmitting terminal, thereby preventing the transmitting terminal from continuously interfering with sidelink or uplink transmissions in neighboring cells.

[0073] <Fourth embodiment> In this embodiment, a modification of the sidelink transmission described in the first embodiment is described. A configuration example of a wireless communication system according to this embodiment is the same as that shown in FIG. 4. In this embodiment, a transmitting terminal (e.g., UE1A) is configured to set a restriction on PSSCH resource allocation for the transmitting terminal over multiple sidelink control periods in accordance with an instruction from eNB2. In this embodiment, an example is shown in which a restriction is set individually for a specific UE1 or a specific UE group in a cell 21.

[0074] In some implementations, the eNB2 may impose a restriction on PSSCH resource allocation across multiple sidelink control periods for some or all sidelink transmitting terminals in the cell 21 when the number of sidelink transmissions (or the number of sidelink transmitting terminals) performed in the cell 21 exceeds a predetermined value. In this case, the restriction may be a lower limit (2 or more) on the number of sidelink control periods during which PSSCH resource allocation is enabled (the number of valid sidelink control periods). This allows the eNB2 to reduce the number of PSCCH transmissions when the number of sidelink transmissions (or the number of sidelink transmitting terminals) performed in the cell 21 is large. This reduces the utilization rate of the PSCCH resource pool. This reduces the probability of collisions occurring when multiple PSCCH transmissions from neighboring sidelink transmitting terminals are performed using the same radio resources.

[0075] 12 is a flowchart showing an example (process 1200) of the operation of the eNB2 according to this embodiment. In block 1201, the eNB2 detects that the number of sidelink transmissions (D2D transmissions) performed in the cell 21 exceeds a predetermined value. In block 1202, the eNB2 sets a limit on PSSCH resource allocation for multiple sidelink control periods (PSCCH periods) to one or more sidelink (D2D) transmitting terminals in the cell 21.

[0076] Finally, a configuration example of UE1 according to the above-described embodiments will be described. FIG. 13 is a block diagram showing a configuration example of UE1. Both the above-described UE1 as a transmitting terminal and the UE1 as a receiving terminal may have the configuration shown in FIG. 13. A radio frequency (RF) transceiver 1301 performs analog RF signal processing for communication with eNB2. The analog RF signal processing performed by the RF transceiver 1301 includes frequency up-conversion, frequency down-conversion, and amplification. The RF transceiver 1301 is coupled to an antenna 1302 and a baseband processor 1303. That is, the RF transceiver 1301 receives modulation symbol data (or OFDM symbol data) from the baseband processor 1303, generates a transmit RF signal, and provides the transmit RF signal to the antenna 1302. The RF transceiver 1301 also generates a baseband receive signal based on the receive RF signal received by the antenna 1302 and provides the baseband receive signal to the baseband processor 1303.

[0077] The baseband processor 1303 performs digital baseband signal processing (data plane processing) and control plane processing for wireless communication. Digital baseband signal processing includes (a) data compression / decompression, (b) data segmentation / concatenation, (c) transmission format (transmission frame) generation / decomposition, (d) transmission path coding / decoding, (e) modulation (symbol mapping) / demodulation, and (f) generation of OFDM symbol data (baseband OFDM signal) using Inverse Fast Fourier Transform (IFFT). Meanwhile, control plane processing includes communication management of Layer 1 (e.g., transmit power control), Layer 2 (e.g., radio resource management and hybrid automatic repeat request (HARQ) processing), and Layer 3 (e.g., signaling related to attachment, mobility, and call management).

[0078] For example, in the case of LTE and LTE-Advanced, the digital baseband signal processing by the baseband processor 1303 may include signal processing of a Packet Data Convergence Protocol (PDCP) layer, a Radio Link Control (RLC) layer, a MAC layer, and a PHY layer. Also, the control plane processing by the baseband processor 1303 may include processing of a Non-Access Stratum (NAS) protocol, an RRC protocol, and a MAC CE.

[0079] The baseband processor 1303 may include a modem processor (e.g., a Digital Signal Processor (DSP)) that performs digital baseband signal processing and a protocol stack processor (e.g., a Central Processing Unit (CPU) or a Micro Processing Unit (MPU)) that performs control plane processing. In this case, the protocol stack processor that performs control plane processing may be shared with the application processor 1304, which will be described later.

[0080] The application processor 1304 is also referred to as a CPU, MPU, microprocessor, or processor core. The application processor 1304 may include multiple processors (multiple processor cores). The application processor 1304 executes a system software program (operating system (OS)) and various application programs (e.g., a call application, a web browser, a mailer, a camera operation application, and a music playback application) read from the memory 1306 or a memory not shown, thereby realizing various functions of the UE1.

[0081] In some implementations, the baseband processor 1303 and the application processor 1304 may be integrated on a single chip, as indicated by the dashed line (1305) in Figure 13. In other words, the baseband processor 1303 and the application processor 1304 may be implemented as a single System on Chip (SoC) device 1305. An SoC device may also be called a system Large Scale Integration (LSI) or a chipset.

[0082] The memory 1306 is volatile memory, nonvolatile memory, or a combination thereof. The memory 1306 may include multiple physically independent memory devices. The volatile memory may be, for example, static random access memory (SRAM), dynamic RAM (DRAM), or a combination thereof. The nonvolatile memory may be mask read only memory (MROM), electrically erasable programmable ROM (EEPROM), flash memory, a hard disk drive, or any combination thereof. For example, the memory 1306 may include an external memory device accessible from the baseband processor 1303, the application processor 1304, and the SoC 1305. The memory 1306 may also include an internal memory device integrated within the baseband processor 1303, the application processor 1304, or the SoC 1305. Furthermore, the memory 1306 may include memory within a universal integrated circuit card (UICC).

[0083] The memory 1306 may store software modules (computer programs) including instructions and data for performing the processes described in the above embodiments by the UE 1. In some implementations, the baseband processor 1303 or the application processor 1304 may be configured to read and execute the software modules from the memory 1306 to perform the processes described in the above embodiments by the UE 1.

[0084] 14 is a block diagram showing an example of the configuration of a base station (eNB) 2 according to the above embodiment. Referring to FIG. 14, the base station 2 includes an RF transceiver 1401, a network interface 1403, a processor 1404, and a memory 1405. The RF transceiver 1401 performs analog RF signal processing for communication with the wireless terminal 1. The RF transceiver 1401 may include multiple transceivers. The RF transceiver 1401 is coupled to an antenna 1402 and the processor 1404. The RF transceiver 1401 receives modulation symbol data (or OFDM symbol data) from the processor 1404, generates a transmit RF signal, and provides the transmit RF signal to the antenna 1402. The RF transceiver 1401 also generates a baseband receive signal based on the receive RF signal received by the antenna 1402 and provides the baseband receive signal to the processor 1404.

[0085] The network interface 1403 is used to communicate with network nodes (e.g., a Mobility Management Entity (MME) and a Serving Gateway (S-GW)). The network interface 1403 may include, for example, a network interface card (NIC) compliant with the IEEE 802.3 series.

[0086] The processor 1404 performs digital baseband signal processing (data plane processing) and control plane processing for wireless communication. For example, in the case of LTE and LTE-Advanced, the digital baseband signal processing by the processor 1404 may include signal processing of a PDCP layer, an RLC layer, a MAC layer, and a PHY layer. Furthermore, the control plane processing by the processor 1404 may include processing of an S1 protocol, an RRC protocol, and a MAC CE.

[0087] The processor 1404 may include multiple processors. For example, the processor 1404 may include a modem processor (e.g., DSP) that performs digital baseband signal processing and a protocol stack processor (e.g., CPU or MPU) that performs control plane processing.

[0088] The memory 1405 is configured by a combination of volatile memory and nonvolatile memory. The volatile memory is, for example, SRAM or DRAM, or a combination thereof. The nonvolatile memory is, for example, MROM, PROM, flash memory, or a hard disk drive, or a combination thereof. The memory 1405 may include storage located remotely from the processor 1404. In this case, the processor 1404 may access the memory 1405 via the network interface 1403 or an I / O interface (not shown).

[0089] The memory 1405 may store software modules (computer programs) including instructions and data for performing the processes described in the above embodiments by the base station 2. In some implementations, the processor 1404 may be configured to read and execute the software modules from the memory 1405 to perform the processes of the base station 2 described in the above embodiments.

[0090] As described with reference to FIGS. 13 and 14 , each of the processors included in the UE1 and the eNB2 according to the above-described embodiments executes one or more programs including instructions for causing a computer to perform the algorithms described with reference to the drawings. The programs can be stored and provided to a computer using various types of non-transitory computer-readable media. Non-transitory computer-readable media include various types of tangible storage media. Examples of non-transitory computer-readable media include magnetic storage media (e.g., flexible disks, magnetic tapes, hard disk drives), magneto-optical storage media (e.g., magneto-optical disks), compact disc read-only memories (CD-ROMs), CD-Rs, CD-R / Ws, and semiconductor memories (e.g., mask ROMs, programmable ROMs (PROMs), erasable PROMs (EPROMs), flash ROMs, and random access memories (RAMs)). The programs may also be provided to a computer by various types of transitory computer-readable media. Examples of transitory computer-readable media include electrical signals, optical signals, and electromagnetic waves. The temporary computer-readable medium can supply the program to the computer via a wired communication path such as an electric wire or an optical fiber, or via a wireless communication path.

[0091] <Other embodiments> The above-described embodiments may be implemented independently of each other, or may be implemented in appropriate combination.

[0092] The above-described embodiments are not limited to LTE-Advanced and its improvements, but may also be applied to D2D communications in other mobile communication networks or systems.

[0093] Furthermore, the above-described embodiments are merely examples of application of the technical ideas obtained by the inventors of the present invention. In other words, the technical ideas are not limited to the above-described embodiments, and various modifications are possible.

[0094] This application claims priority based on Japanese Patent Application No. 2015-141124, filed on July 15, 2015, the disclosure of which is incorporated herein by reference in its entirety.

[0095] For example, some or all of the above embodiments can be described as, but are not limited to, the following supplementary notes. (Appendix 1) at least one radio transceiver; at least one processor coupled to the at least one wireless transceiver and configured to perform data transmission to other wireless terminals without going through a base station according to a periodic device-to-device (D2D) control period; Equipped with each D2D control period includes a first subframe pool consisting of a plurality of subframes usable for transmission of D2D control information and a second subframe pool consisting of a plurality of subframes usable for the data transmission according to the D2D control information; the at least one processor is configured to transmit first D2D control information in one or more subframes in the first subframe pool within a first D2D control period, and to perform the data transmission according to the first D2D control information in one or more subframes in the second subframe pool within the first D2D control period; the first D2D control information includes a first information element for identifying one or more subframes in the second subframe pool within the first D2D control period; the first D2D control information further includes a second information element indicating whether the first D2D control information is valid in at least one D2D control period after the first D2D control period; Transmitting terminal. (Appendix 2) the at least one processor is configured to perform the data transmission without transmitting new D2D control information in the at least one D2D control period when the first D2D control information remains valid in the at least one D2D control period. 2. The transmitting terminal according to claim 1. (Appendix 3) the second information element indicates a length of the at least one D2D control period. 3. A transmitting terminal according to claim 1 or 2. (Appendix 4) the second information element indicates whether radio resource allocation for the data transmission based on the first D2D control information is to be continued; 3. A transmitting terminal according to claim 1 or 2. (Appendix 5) the at least one processor is configured to transmit, during any one of the at least one D2D control period, second D2D control information indicating that radio resource allocation for the data transmission based on the first D2D control information is disabled. A transmitting terminal according to any one of appendixes 1 to 4. (Appendix 6) the at least one processor is configured to set a limit on the at least one D2D control period in the transmitting terminal autonomously or according to an instruction from the base station. 6. The transmitting terminal according to any one of Supplementary notes 1 to 5. (Appendix 7) the restriction includes at least one of: (a) continuous activation of the first D2D control information is not permitted; (b) an upper limit is set on the length of the at least one D2D control period; or (c) a lower limit is set on the length of the at least one D2D control period. 7. The transmitting terminal according to claim 6. (Appendix 8) the at least one processor is configured to, when it is estimated that the transmitting terminal is located at a cell boundary between a cell of the base station and an adjacent cell, set the restriction on the transmitting terminal, including (a) not allowing continuous activation of the first D2D control information, or (b) setting an upper limit value on a length of the at least one D2D control period. 8. The transmitting terminal of claim 7. (Appendix 9) the restriction includes setting a lower limit on the length of the at least one D2D control period; the at least one processor sets the lower limit value in accordance with an instruction from the base station. 8. The transmitting terminal of claim 7. (Appendix 10) the at least one processor sets the lower limit value in accordance with an instruction from the base station when the number of D2D transmissions performed within a cell of the base station exceeds a predetermined value. 10. The transmitting terminal according to claim 9. (Appendix 11) A method in a transmitting terminal, comprising: transmitting data to a receiving terminal without going through a base station in accordance with a periodic device-to-device (D2D) control period; each D2D control period includes a first subframe pool consisting of a plurality of subframes usable for transmission of D2D control information and a second subframe pool consisting of a plurality of subframes usable for the data transmission according to the D2D control information; performing the D2D transmission includes transmitting first D2D control information in one or more subframes in the first subframe pool within a first D2D control period, and performing the data transmission in accordance with the first D2D control information in one or more subframes in the second subframe pool within the first D2D control period; the first D2D control information includes a first information element for identifying one or more subframes in the second subframe pool within the first D2D control period; the first D2D control information further includes a second information element indicating whether the first D2D control information is valid in at least one D2D control period after the first D2D control period; method. (Appendix 12) performing the D2D transmission includes, when the first D2D control information remains valid in the at least one D2D control period, performing the data transmission without transmitting new D2D control information in the at least one D2D control period. The method described in Appendix 11. (Appendix 13) the second information element indicates a length of the at least one D2D control period. 13. The method according to claim 11 or 12. (Appendix 14) the second information element indicates whether radio resource allocation for the data transmission based on the first D2D control information is to be continued; The method described in Appendix 11 or 1 is as described in 2. (Appendix 15) transmitting, in any one of the at least one D2D control period, second D2D control information indicating that radio resource allocation for the data transmission based on the first D2D control information is disabled. The method according to any one of appendices 11 to 14. (Appendix 16) setting the limit on the at least one D2D control period autonomously or according to an instruction from the base station. The method according to any one of appendices 11 to 15. (Appendix 17) A non-transitory computer-readable medium storing a program for causing a computer to perform a method in a transmitting terminal, the method comprising transmitting data to a receiving terminal without going through a base station in accordance with a periodic device-to-device (D2D) control period; each D2D control period includes a first subframe pool consisting of a plurality of subframes usable for transmission of D2D control information and a second subframe pool consisting of a plurality of subframes usable for the data transmission according to the D2D control information; performing the D2D transmission includes transmitting first D2D control information in one or more subframes in the first subframe pool within a first D2D control period, and performing the data transmission in accordance with the first D2D control information in one or more subframes in the second subframe pool within the first D2D control period; the first D2D control information includes a first information element for identifying one or more subframes in the second subframe pool within the first D2D control period; the first D2D control information further includes a second information element indicating whether the first D2D control information is valid in at least one D2D control period after the first D2D control period; Non-transitory computer-readable medium. (Appendix 18) at least one radio transceiver; at least one processor coupled to the at least one wireless transceiver and configured to receive data from a transmitting terminal without going through a base station according to a periodic device-to-device (D2D) control period; Equipped with each D2D control period includes a first subframe pool consisting of a plurality of subframes usable for transmitting D2D control information and a second subframe pool consisting of a plurality of subframes usable for receiving the data according to the D2D control information; the at least one processor is configured to receive first D2D control information in one or more subframes in the first subframe pool within a first D2D control period, and to perform the data reception in one or more subframes in the second subframe pool within the first D2D control period according to the first D2D control information; the first D2D control information includes a first information element for identifying one or more subframes in the second subframe pool within the first D2D control period; the first D2D control information further includes a second information element indicating whether the first D2D control information is valid in at least one D2D control period after the first D2D control period; Receiving terminal. (Appendix 19) the at least one processor is configured to perform the data reception without receiving new D2D control information in the at least one D2D control period when the first D2D control information remains valid in the at least one D2D control period. 19. The receiving terminal of claim 18. (Appendix 20) the at least one processor is configured to disable radio resource allocation based on the first D2D control information in the at least one D2D control period when the data reception does not occur for a predetermined period in the at least one D2D control period. 20. A receiving terminal according to claim 18 or 19. (Appendix 21) 1. A method in a receiving terminal, comprising: receiving data from a transmitting terminal without going through a base station in accordance with a periodic device-to-device (D2D) control period; each D2D control period includes a first subframe pool consisting of a plurality of subframes usable for transmitting D2D control information and a second subframe pool consisting of a plurality of subframes usable for receiving the data according to the D2D control information; performing the data reception includes receiving first D2D control information in one or more subframes in the first subframe pool within a first D2D control period, and performing the data reception in accordance with the first D2D control information in one or more subframes in the second subframe pool within the first D2D control period; the first D2D control information includes a first information element for identifying one or more subframes in the second subframe pool within the first D2D control period; the first D2D control information further includes a second information element indicating whether the first D2D control information is valid in at least one D2D control period after the first D2D control period; method. (Appendix 22) performing the data reception includes, when the first D2D control information remains valid in the at least one D2D control period, performing the data reception without receiving new D2D control information in the at least one D2D control period. 22. The method described in Appendix 21. (Appendix 23) and further comprising: when the data reception does not occur for a predetermined period within the at least one D2D control period, disabling radio resource allocation based on the first D2D control information in the at least one D2D control period. 23. The method according to claim 21 or 22. (Appendix 24) A non-transitory computer-readable medium storing a program for causing a computer to perform a method in a receiving terminal, the method comprising receiving data from a transmitting terminal without going through a base station in accordance with a periodic device-to-device (D2D) control period; each D2D control period includes a first subframe pool consisting of a plurality of subframes usable for transmitting D2D control information and a second subframe pool consisting of a plurality of subframes usable for receiving the data according to the D2D control information; performing the data reception includes receiving first D2D control information in one or more subframes in the first subframe pool within a first D2D control period, and performing the data reception in accordance with the first D2D control information in one or more subframes in the second subframe pool within the first D2D control period; the first D2D control information includes a first information element for identifying one or more subframes in the second subframe pool within the first D2D control period; the first D2D control information further includes a second information element indicating whether the first D2D control information is valid in at least one D2D control period after the first D2D control period; Non-transitory computer-readable medium. (Appendix 25) A base station, a wireless transceiver configured to communicate with a plurality of wireless terminals within the cell; at least one processor configured to control data transmission from a first wireless terminal to a second wireless terminal according to a periodic device-to-device (D2D) control period without going through the base station; Equipped with each D2D control period includes a first subframe pool consisting of a plurality of subframes usable for transmission of D2D control information and a second subframe pool consisting of a plurality of subframes usable for the data transmission according to the D2D control information; the at least one processor is configured to transmit to the first wireless terminal a D2D grant message indicating a radio resource allocation for the transmission of the D2D control information and the data transmission within a first D2D control period, and indicating that the radio resource allocation is also valid for at least one D2D control period after the first D2D control period. Base station. (Appendix 26) the at least one processor is configured to set a limit on the at least one D2D control period for the first wireless terminal. 26. The base station of claim 25. (Appendix 27) the restriction includes setting a lower limit on the length of the at least one D2D control period. 27. The base station of claim 26. (Appendix 28) the at least one processor is configured to set the lower limit value to the first wireless terminal when a number of D2D transmissions performed in the cell exceeds a predetermined value. 28. The base station of claim 27. (Appendix 29) 1. A method in a base station, comprising: controlling data transmission from a first wireless terminal to a second wireless terminal without going through the base station according to a periodic device-to-device (D2D) control period; each D2D control period includes a first subframe pool consisting of a plurality of subframes usable for transmission of D2D control information and a second subframe pool consisting of a plurality of subframes usable for the data transmission according to the D2D control information; the controlling includes transmitting, to the first wireless terminal, a D2D grant message indicating radio resource allocation for the transmission of the D2D control information and the data transmission within a first D2D control period, and indicating that the radio resource allocation is also valid in at least one D2D control period after the first D2D control period. method. (Appendix 30) the controlling includes setting a limit on at least one D2D control period on the first wireless terminal. 29. The method described in Appendix 29. (Appendix 31) the restriction includes setting a lower limit on the length of the at least one D2D control period. 31. The method described in Appendix 30. (Appendix 32) the setting includes setting the lower limit value to the first wireless terminal when a number of D2D transmissions performed within a cell of the base station exceeds a predetermined value. 3. The method described in Appendix 31. (Appendix 33) A non-transitory computer-readable medium storing a program for causing a computer to perform a method in a base station, The method comprises controlling data transmission from a first wireless terminal to a second wireless terminal without going through the base station according to a periodic device-to-device (D2D) control period; each D2D control period includes a first subframe pool consisting of a plurality of subframes usable for transmission of D2D control information and a second subframe pool consisting of a plurality of subframes usable for the data transmission according to the D2D control information; the controlling includes transmitting, to the first wireless terminal, a D2D grant message indicating radio resource allocation for the transmission of the D2D control information and the data transmission within a first D2D control period, and indicating that the radio resource allocation is also valid in at least one D2D control period after the first D2D control period. Non-transitory computer-readable medium. [Explanation of symbols]

[0096] 1 UE 2 eNB 1301 radio frequency (RF) transceiver 1303 Baseband Processor 1304 Application Processor 1306 memory 1401 RF Transceiver 1404 processor 1405 memory

Claims

1. Transmitting a Physical Sidelink Control Channel (PSCCH) including sidelink control information for scheduling a Physical Sidelink Shared Channel (PSSCH) during a first time period, and transmitting the PSSCH using a first radio resource allocation during the first time period; the sidelink control information includes first information and second information; the first information indicates the first radio resource allocation for the PSSCH transmission; the second information indicates whether the first radio resource allocation is to be valid during a plurality of second time periods; transmitting the PSSCH with the first radio resource allocation in each second period of the plurality of second periods subsequent to the first period based on the first information and the second information; Terminal device method.

2. Transmitting a Physical Sidelink Control Channel (PSCCH) including sidelink control information for scheduling a Physical Sidelink Shared Channel (PSSCH) during a first time period, and transmitting the PSSCH using a first radio resource allocation during the first time period; the sidelink control information includes first information and second information; the first information indicates the first radio resource allocation for the PSSCH transmission; the second information indicates whether the first radio resource allocation is to be enabled in a plurality of second time periods; The transmitter transmits the PSSCH using the first radio resource allocation in each second period of the plurality of second periods subsequent to the first period, based on the first information and the second information. Terminal device.

3. The length of the first period and the length of the second period are the same. The terminal device according to claim 2 .

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