Transmitting device, method and integrated circuit for radio resource selection and sensing

Abstract

The present disclosure relates to a transmitting device, method, and integrated circuit for radio resource selection and sensing. The transmitting device is used to determine radio resources to be used for data transmission from the transmitting device to one or more receiving devices via a sidelink interface. After data transmission is triggered, the transmitting device performs autonomous radio resource allocation to select radio resources to be used for data transmission within a transmission window based on the results of a resource sensing process during a sensing window before the data transmission is triggered. Autonomous radio resource allocation selects radio resources in a primary subframe of the transmission window relative to radio resources in a secondary subframe of the transmission window. The secondary subframes in the transmission window correspond to those subframes in the sensing window for which the transmitting device did not perform a resource sensing process, and the primary subframes in the transmission window correspond to those subframes in the sensing window for which the transmitting device performed a resource sensing process. The transmission window starts after data transmission is triggered.

Description

[0001] The present disclosure is a divisional application of an invention patent application filed on August 9, 2016, with application number 201680089558.9, entitled “IMPROVED RADIO RESOURCE SELECTION AND SENSING FOR V2X TRANSMISSIONS” and the applicant being Panasonic Corporation (USA). Technical Field

[0002] The present disclosure relates to an improved transmitting apparatus for performing radio resource selection and sensing procedures. The present disclosure provides corresponding methods and apparatus for the present invention. Background Art

[0003] Long Term Evolution (LTE)

[0004] The third generation of mobile systems (3G), based on WCDMA radio access technology, is being widely deployed around the world. The first step in enhancing or evolving this technology is to introduce High Speed ​​Downlink Packet Access (HSDPA) and enhanced uplink (also known as High Speed ​​Uplink Packet Access (HUSPA)), thereby providing a highly competitive radio access technology.

[0005] To prepare for further growth in user demand and to be competitive with new radio access technologies, 3GPP introduced a new mobile communication system called Long Term Evolution (LTE). LTE is designed to meet the carrier needs for high-speed data and media transmission and large-capacity voice support for the next decade. The ability to provide high bit rates is a key feature of LTE.

[0006] The work item (WI) specification for the Long Term Evolution (LTE), known as Evolved UMTS Terrestrial Radio Access (UTRA) and UMTS Terrestrial Radio Access Network (UTRAN), was finalized as Release 8 (LTE Release 8). The LTE system represents an efficient packet-based radio access and radio access network that provides all-IP-based functionality with low latency and low cost. In LTE, multiple adjustable transmission bandwidths, such as 1.4, 3.0, 5.0, 10.0, 15.0, and 20.0 MHz, are specified to achieve flexible system deployment using a given spectrum. In the downlink, radio access based on orthogonal frequency division multiplexing (OFDM) is adopted due to its inherent immunity to multipath interference (MPI), which is achieved by the low symbol rate, the use of a cyclic prefix (CP), and its association with different transmission bandwidth arrangements. In the uplink, radio access based on single-carrier frequency division multiple access (SC-FDMA) is adopted because, given the limited transmission power of user equipment (UE), providing wide-area coverage takes precedence over increasing the peak data rate. Many key packet radio access technologies, including Multiple Input Multiple Output (MIMO) channel transmission technology, are adopted, and an efficient control signaling structure is implemented in LTE Release 8 / 9.

[0007] LTE Architecture

[0008] Figure 1 The overall LTE architecture is shown in Figure 1. The E-UTRAN comprises eNodeBs, which provide the E-UTRA user plane (PDCP / RLC / MAC / PHY) and control plane (RRC) protocol terminations towards the user equipment (UE). The eNodeB (eNB) hosts the physical (PHY), medium access control (MAC), radio link control (RLC) and packet data control protocol (PDCP) layers, which include functionality for user plane header compression and encryption. The eNodeB also provides radio resource control (RRC) functionality corresponding to the control plane. The eNodeB performs many functions, including radio resource management, admission control, scheduling, imposing negotiated uplink quality of service (QoS), cell information broadcast, encryption / decryption of user and control plane data, and compression / decompression of downlink / uplink user plane packet headers. The eNodeBs are interconnected to each other via the X2 interface.

[0009] The eNodeB is also connected to the EPC (Evolved Packet Core) via the S1 interface, more specifically to the MME (Mobility Management Entity) via S1-MME and to the Serving Gateway (SGW) via S1-U. The S1 interface supports a many-to-many relationship between the MME / Serving Gateway and the eNodeB. The SGW routes and forwards user data packets, and also acts as a mobility anchor for the user plane during handover between eNodeBs, and as an anchor for mobility between LTE and other 3GPP technologies (terminating the S4 interface and relaying traffic between the 2G / 3G system and the PDN GW). For user equipment in idle state, the SGW terminates the downlink data path and triggers paging when downlink data for the user equipment arrives. The SGW manages and stores user equipment contexts, such as parameters for IP bearer services, network internal routing information. In the case of lawful interception, the SGW also performs replication of user traffic.

[0010] The MME is the key control node for the LTE access network. The MME is responsible for idle mode user equipment tracking and paging procedures, including retransmissions. The MME participates in bearer activation / deactivation processing and is also responsible for selecting the SGW for the user equipment at the time of initial attach and in the case of intra-LTE handover involving core network (CN) node relocation. The MME is responsible for authenticating the user (by interacting with the HSS). Non-access stratum (NAS) signaling terminates at the MME, and the MME is also responsible for generating and assigning temporary identities to user equipment. The MME checks the authorization of the user equipment to reside on the service provider's public land mobile network (PLMN) and imposes roaming restrictions on the user equipment. The MME is the endpoint in the network for ciphering / integrity protection of NAS signaling and handles security key management. The MME also supports lawful interception of signaling. The MME also provides control plane functions for mobility between LTE and 2G / 3G access networks using the S3 interface that terminates at the MME from the SGSN. The MME also terminates the S6a interface towards the home HSS for roaming user equipment.

[0011] Component Carrier Structure in LTE

[0012] The downlink component carriers of a 3GPP LTE system are subdivided in the time-frequency domain into so-called subframes. Figure 2The two downlink time slots shown in FIG, the first downlink time slot includes a control channel region (PDCCH region) within the first OFDM symbol. Each subframe includes a given number of OFDM symbols in the time domain (12 or 14 OFDM symbols in 3GPP LTE (Release 8)), each OFDM symbol spanning the entire bandwidth of the component carrier. Therefore, each OFDM symbol includes a number of modulation symbols transmitted on the corresponding subcarriers. In LTE, the transmission signal in each time slot is composed of subcarriers and The resource grid description of OFDM symbols. is the number of resource blocks within the bandwidth. Depends on the downlink transmission bandwidth configured in the cell and should satisfy in and are the minimum and maximum downlink bandwidths, respectively, supported by the current version of the specification. The number of subcarriers in a resource block. For the conventional cyclic prefix subframe structure, and

[0013] Assuming a multi-carrier communication system employing OFDM, such as used in 3GPP Long Term Evolution (LTE), the smallest unit of resources that can be allocated by the scheduling unit is a "resource block." A physical resource block (PRB) is defined as consecutive OFDM symbols in the time domain (e.g., 7 OFDM symbols) and consecutive subcarriers in the frequency domain, such as Figure 2 (e.g., 12 subcarriers for a component carrier). In 3GPP LTE (Release 8), a physical resource block thus comprises resource elements corresponding to one slot in the time domain and 180 kHz in the frequency domain (for further details on the downlink resource grid, see, e.g., 3GPP TS 36.211, "Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation (Release 8)", current version 13.1.0, section 6.2, which is available at http: / / www.3gpp.org and incorporated herein by reference).

[0014] A subframe consists of two time slots, so that there are 14 OFDM symbols in a subframe when a so-called "normal" CP (cyclic prefix) is used, and there are 12 OFDM symbols in a subframe when an "extended" CP is used. For reasons of terminology, time-frequency resources that are equivalent to the same consecutive subcarriers spanning a complete subframe are hereinafter referred to as a "resource block pair," or equivalently, an "RB pair" or "PRB pair."

[0015] The term "component carrier" refers to a combination of several resource blocks in the frequency domain. In future versions of LTE, the term "component carrier" will no longer be used; instead, the term will be changed to "cell," which refers to a combination of downlink and optional uplink resources. The relationship between the carrier frequencies of downlink resources and uplink resources is indicated in system information transmitted on the downlink resources.

[0016] Similar assumptions about the component carrier structure will also apply to later releases.

[0017] Carrier aggregation in LTE-A to support wider bandwidth

[0018] The spectrum for IMT-Advanced was determined at the World Radiocommunication Conference 2007 (WRC-07). While the overall spectrum for IMT-Advanced was determined, the actual frequency bandwidth available varies by region or country. However, after determining the outline of the available spectrum, the Third Generation Partnership Project (3GPP) began standardizing the radio interface. At the 3GPP TSG RAN#39 meeting, a study item description for "Further development of E-UTRA (LTE-Advanced)" was approved. This study item covers, for example, the technical aspects of E-UTRA evolution to meet the requirements of IMT-Advanced.

[0019] LTE-Advanced systems support a bandwidth of 100 MHz, while LTE systems only support 20 MHz. The lack of radio spectrum has become a bottleneck in wireless network development, making it difficult to find spectrum bands wide enough for LTE-Advanced systems. Therefore, there is an urgent need to find ways to access wider radio spectrum bands, and a possible answer is carrier aggregation functionality.

[0020] In carrier aggregation, two or more component carriers are aggregated to support a wider transmission bandwidth of up to 100 MHz. Several cells in an LTE system are aggregated into one wider channel in an LTE-Advanced system (which is wide enough for 100 MHz), even though the cells in LTE may be in different frequency bands.

[0021] All component carriers can be configured to be compatible with LTE Release 8 / 9, at least when the bandwidth of the component carrier does not exceed the bandwidth supported by the LTE Release 8 / 9 cell. Not all component carriers aggregated by a user equipment must be compatible with LTE Release 8 / 9. Existing mechanisms (e.g., barring) can be used to prevent Release 8 / 9 user equipment from camping on a component carrier.

[0022] A user equipment can receive or transmit simultaneously on one or more component carriers (corresponding to multiple serving cells) depending on its capabilities. An LTE-A Release 10 user equipment with reception and / or transmission capabilities for carrier aggregation can receive and / or transmit simultaneously on multiple serving cells, while an LTE Release 8 / 9 user equipment can receive and transmit only on a single serving cell, provided that the component carrier structure follows the Release 8 / 9 specifications.

[0023] Carrier aggregation is supported for both contiguous and non-contiguous component carriers, limiting each component carrier to a maximum of 110 resource blocks in the frequency domain (using 3GPP LTE (Release 8 / 9) numerology).

[0024] 3GPP LTE-A (Release 10) compatible user equipment can be configured to aggregate different numbers of component carriers originating from the same eNodeB (base station) and possibly having different bandwidths in the uplink and downlink. The number of configurable downlink component carriers depends on the downlink aggregation capability of the UE. In contrast, the number of configurable uplink component carriers depends on the uplink aggregation capability of the UE. It may not currently be possible to configure a mobile terminal with more uplink component carriers than downlink component carriers. In a typical TDD deployment, the number of component carriers and the bandwidth of each component carrier are the same in the uplink and downlink. Component carriers originating from the same eNodeB do not need to provide the same coverage.

[0025] The spacing between the center frequencies of consecutively aggregated component carriers should be a multiple of 300kHz. This is to be compatible with the 100kHz frequency raster of 3GPP LTE (Release 8 / 9) while maintaining orthogonality of subcarriers with 15kHz spacing. Depending on the aggregation scenario, n×300kHz spacing can be facilitated by inserting a small number of unused subcarriers between consecutive component carriers.

[0026] The nature of the aggregation of multiple carriers is only exposed upwards to the MAC layer. For both uplink and downlink, a HARQ entity is required in the MAC for each aggregated component carrier. (In the absence of SU-MIMO for uplink), there is at most one transport block per component carrier. A transport block and its potential HARQ retransmissions need to be mapped to the same component carrier.

[0027] When carrier aggregation is configured, the mobile terminal has only one RRC connection with the network. Upon RRC connection establishment / re-establishment, one cell provides security inputs (one ECGI, one PCI and one ARFCN) as well as non-access stratum mobility information (e.g. TAI), similarly as in LTE Release 8 / 9. After RRC connection establishment / re-establishment, the component carrier corresponding to that cell is called the downlink primary cell (PCell). For each user equipment in the connected state, one and only one downlink PCell (DL PCell) and one uplink PCell (UL PCell) are always configured. Within the configured component carrier set, the other cells are called secondary cells (SCells); the carriers of the SCells are the downlink secondary component carrier (DL SCC) and the uplink secondary component carrier (UL SCC). A maximum of five serving cells, including the PCell, can be configured for one UE.

[0028] MAC layer / entity, RRC layer, physical layer

[0029] The LTE layer 2 user plane / control plane protocol stack includes four sublayers, namely, RRC, PDCP, RLC and MAC. The medium access control (MAC) layer is the lowest sublayer in the layer 2 architecture of the LTE radio protocol stack and is defined by, for example, the current version 13.2.0 of the 3GPP technical standard TS 36.321. The connection to the physical layer below is through transport channels, and the connection to the RLC layer above is through logical channels. Therefore, the MAC layer performs multiplexing and demultiplexing between logical channels and transport channels: the MAC layer in the transmitting side constructs MAC PDUs (called transport blocks) from MAC SDUs received through logical channels, and the MAC layer in the receiving side restores MAC SDUs from MAC PDUs received through transport channels.

[0030] The MAC layer provides data transfer services to the RLC layer through logical channels (see subsections 5.4 and 5.3 of TS 36.321, incorporated herein by reference). These logical channels are control logical channels that carry control data (e.g., RRC signaling) or traffic logical channels that carry user plane data. On the other hand, data from the MAC layer is exchanged with the physical layer through transport channels classified as downlink or uplink. Data is multiplexed into transport channels depending on how it is transmitted over the air.

[0031] The physical layer is responsible for the actual transmission of data and control information over the air interface, that is, the physical layer carries all information from the MAC transport channel over the air interface on the transmitting side. Some important functions performed by the physical layer include coding and modulation, link adaptation (AMC), power control, cell search (for initial synchronization and handover purposes), and other measurements for the RRC layer (within the LTE system and between systems). The physical layer performs transmission based on transmission parameters such as modulation scheme, coding rate (i.e., modulation and coding scheme, MCS), number of physical resource blocks, etc. More information about the functions of the physical layer can be found in the current version 13.1.1 of the 3GPP technical standard 36.213, which is incorporated herein by reference.

[0032] The Radio Resource Control (RRC) layer controls the communication between the UE and the eNB at the radio interface, as well as the mobility of the UE across several cells. The RRC protocol also supports the transfer of NAS information. For UEs in RRC_IDLE, RRC supports notifications from the incoming network. RRC connection control covers all procedures related to the establishment, modification, and release of RRC connections, including paging, measurement configuration and reporting, radio resource configuration, initial security activation, and the establishment of signaling radio bearers (SRBs) and radio bearers carrying user data (data radio bearers, DRBs).

[0033] The Radio Link Control (RLC) sublayer primarily includes ARQ functionality and supports data segmentation and concatenation. Specifically, the RLC layer performs framing of RLC SDUs to fit them into the size indicated by the MAC layer. The latter two minimize protocol overhead independently of the data rate. The RLC layer is connected to the MAC layer via logical channels. Each logical channel carries different types of services. The layer above the RLC layer is typically the PDCP layer, but in some cases, the layer above the RLC layer is the RRC layer. Specifically, RRC messages transmitted on the logical channels BCCH (Broadcast Control Channel), PCCH (Paging Control Channel), and CCCH (Common Control Channel) do not require security protection and therefore bypass the PDCP layer and go directly to the RLC layer.

[0034] Uplink access scheme for LTE

[0035] For uplink transmission, power-efficient user terminal transmission is required to maximize coverage. Single-carrier transmission combined with FDMA with dynamic bandwidth allocation has been selected as the evolved UTRA uplink transmission scheme. The main reasons for preferring single-carrier transmission are the lower peak-to-average power ratio (PAPR) compared to multi-carrier signals (OFDMA), and the corresponding improved power amplifier efficiency and improved coverage (higher data rates for a given terminal peak power). During each time interval, the eNodeB allocates unique time / frequency resources to each user for transmitting user data, thereby ensuring intra-cell orthogonality. Orthogonal access in the uplink ensures improved spectral efficiency by eliminating intra-cell interference. The insertion of a cyclic prefix into the transmitted signal helps the base station (eNodeB) handle interference caused by multipath propagation.

[0036] The basic physical resource for data transmission consists of a frequency resource of size BWgrant during a time interval (e.g., a subframe), to which the coded information bits are mapped. It should be noted that a subframe (also called a transmission time interval (TTI)) is the minimum time interval for user data transmission. However, a frequency resource BWgrant over a period longer than one TTI can be allocated to a user by concatenating subframes.

[0037] Layer 1 / Layer 2 control signaling

[0038] In order to inform the scheduled users of their assignment status, transmission format and other transmission-related information (e.g., HARQ information, transmit power control (TPC) commands), L1 / L2 control signaling is transmitted together with the data on the downlink. Assuming that the user assignment can change from subframe to subframe, L1 / L2 control signaling is multiplexed with the downlink data in the subframe. It should be noted that user assignment can also be performed based on TTI (Transmission Time Interval), and the TTI length can be a multiple of the subframe. The TTI length can be fixed for all users in the service area, can be different for different users, or can even be dynamic for each user. Generally, L1 / L2 control signaling only needs to be transmitted once per TTI. Without loss of generality, it is assumed below that TTI is equivalent to one subframe.

[0039] L1 / L2 control signaling is transmitted on the Physical Downlink Control Channel (PDCCH). The PDCCH carries messages known as Downlink Control Information (DCI), which in most cases includes resource allocations and other control information for a mobile terminal or group of UEs. Several PDCCHs can be transmitted in one subframe.

[0040] Generally, the information sent in L1 / L2 control signaling for allocating uplink or downlink radio resources (particularly LTE(-A) Release 10) can be categorized into the following items:

[0041] - User ID , indicating the assigned user. This is usually included in the checksum by masking the CRC with the user ID;

[0042] - Resource allocation information , represents the resources (e.g., resource blocks, RBs) assigned to the user. Alternatively, this information is called resource block allocation (RBA). Note that the number of RBs assigned to a user can be dynamic;

[0043] - Carrier indicator , which is used in the case where a control channel transmitted on a first carrier allocates resources on a second carrier (i.e., resources on or associated with the second carrier) (cross-carrier scheduling);

[0044] - Modulation and coding schemes , which determines the modulation scheme and coding rate adopted;

[0045] - HARQ information , such as a New Data Indicator (NDI) and / or a Redundancy Version (RV), which are particularly useful in retransmissions of data packets or parts thereof;

[0046] - Power control commands , used to adjust the transmission power of the allocated uplink data or control information transmission;

[0047] - Reference signal information , such as an applied cyclic shift and / or orthogonal cover code index to be used for transmission or reception of a reference signal associated with the allocation;

[0048] - Uplink or downlink allocation index , which is used to identify the allocation order, which is particularly useful in TDD systems;

[0049] - Hopping information , e.g., an indication of whether and how to apply resource hopping to increase frequency diversity;

[0050] - CSI Request , which is used to trigger the transmission of channel state information in the allocated resources; and

[0051] - Multi-cluster information , which is a flag used to indicate and control whether transmission occurs in a single cluster (a contiguous set of RBs) or multiple clusters (at least two non-contiguous sets of contiguous RBs). Multi-cluster allocation has been introduced by 3GPP LTE-(A) Release 10.

[0052] It should be noted that the above list is non-exhaustive and, depending on the used DCI format, not all mentioned information items need to be present in every PDCCH transmission.

[0053] Downlink control information appears in several formats that differ in their overall size and in the information contained in their fields, as described above. The different DCI formats currently defined for LTE are as follows and are described in detail in 3GPP TS 36.212, "Multiplexing and channel coding," section 5.3.3.1 (current version v.13.1.0 available at http: / / www.3gpp.org and incorporated herein by reference). 3GPP technical standard TS 36.212, current version 13.1.0, defines control information for the sidelink in subsection 5.4.3, which is incorporated herein by reference.

[0054] Semi-Persistent Scheduling (SPS)

[0055] In the downlink and uplink, the scheduling eNodeB dynamically allocates resources to the user equipment via the L1 / L2 control channel (PDCCH) in each transmission time interval, where the user equipment is addressed via the user equipment-specific C-RNTI. As mentioned above, the CRC of the PDCCH is masked with the C-RNTI of the addressed user equipment (so-called dynamic PDCCH). Only user equipment with a matching C-RNTI can correctly decode the PDCCH content, that is, the CRC check is positive. This type of PDCCH signaling is also called dynamic (scheduling) grant. The user equipment monitors the L1 / L2 control channel for dynamic grants in each transmission time interval to find possible assignments (downlink and uplink) to which it can be allocated.

[0056] In addition, the E-UTRAN can persistently allocate uplink / downlink resources for initial HARQ transmissions. Retransmissions are explicitly signaled via L1 / L2 control channels when needed. Because retransmissions are dynamically scheduled, this operation is called semi-persistent scheduling (SPS), i.e., allocating resources to user equipment on a semi-persistent basis (semi-persistent resource allocation). The benefit is that PDCCH resources used for initial HARQ transmissions are conserved. Semi-persistent scheduling can be used in PCells in Release 10, but not in SCells.

[0057] An example of a service that can be scheduled using semi-persistent scheduling is Voice over IP (VoIP). During a talk-spurt, VoIP packets are generated every 20 ms at the codec. Therefore, the eNodeB can persistently allocate uplink or, respectively, downlink resources every 20 ms, which can then be used for the transmission of the VoIP packets. In general, semi-persistent scheduling is beneficial for services with predictable traffic behavior, i.e., a constant bit rate with periodic packet arrival times.

[0058] The user equipment also monitors the PDCCH in subframes in which it has been persistently assigned resources for initial transmissions. Dynamic (scheduling) grants (i.e., PDCCHs with a C-RNTI-masked CRC) can override semi-persistent resource assignments. In the event that the user equipment finds its C-RNTI on the L1 / L2 control channel in a subframe in which the user equipment has allocated semi-persistent resources, this L1 / L2 control channel assignment overrides the persistent resource assignment for that transmission time interval, and the user equipment does not follow the dynamic grant. When the user equipment does not find a dynamic grant, it will transmit / receive according to the semi-persistent resource assignment.

[0059] Configuration of semi-persistent scheduling is performed via RRC signaling. For example, within radio resource control (RRC) signaling, the periodicity of the persistent assignment, e.g., PS_PERIOD, is signaled. The activation and precise timing of the persistent assignment, as well as the physical resource and transport format parameters, are signaled via PDCCH signaling. Once semi-persistent scheduling is activated, the user equipment follows the semi-persistent resource assignment according to the SPS activation PDCCH every PS_PERIOD. Essentially, the user equipment stores the SPS activation PDCCH content and follows the PDCCH at the signaled periodicity.

[0060] In order to distinguish dynamic PDCCH from the PDCCH that activates semi-persistent scheduling (also known as SPS activation PDCCH), a separate identifier is introduced. Basically, the CRC of the SPS activation PDCCH is masked with this additional identifier, which is referred to as the SPS C-RNTI below. The size of the SPS C-RNTI is also 16 bits, the same as the regular C-RNTI. In addition, the SPS C-RNTI is also user equipment specific, that is, each user equipment configured for semi-persistent scheduling is assigned a unique SPS C-RNTI.

[0061] In the case where the user equipment detects that a semi-persistent resource allocation is activated by the corresponding SPS activation PDCCH, the user equipment will store the PDCCH content (i.e., semi-persistent resource allocation) and apply it for each semi-persistent scheduling interval, i.e., the periodicity signaled via RRC. As already mentioned, dynamic allocations (i.e., signaled on the dynamic PDCCH) are only "one-time allocations". The SPS C-RNTI is also used to signal the retransmission of the SPS allocation. In order to distinguish SPS activation from SPS retransmission, the NDI (New Data Indicator) bit is used. SPS activation is indicated by setting the NDI bit to 0. The SPS PDCCH with the NDI bit set to 1 indicates a retransmission of the initial transmission for semi-persistent scheduling.

[0062] Similar to the activation of semi-persistent scheduling, the eNodeB can also disable semi-persistent scheduling, also known as SPS resource release. There are several options for how to signal the de-assignment of semi-persistent scheduling. One option would be to use PDCCH signaling, where some PDCCH fields are set to certain predefined values, i.e., an SPS PDCCH indicating a zero-size resource assignment. Another option would be to use MAC control signaling.

[0063] LTE Device-to-Device (D2D) Proximity Services (ProSe)

[0064] Proximity-based applications and services represent an emerging socio-technical trend. Identified areas include commercial services and public safety-related services that will be of interest to operators and users. The introduction of Proximity Services (ProSe) capabilities in LTE will enable the 3GPP industry to serve this developing market and, at the same time, address the pressing needs of several public safety groups working together on LTE.

[0065] Device-to-device (D2D) communication is a technology component introduced in LTE Release 12, which enables D2D as an underlay for cellular networks to increase spectral efficiency. For example, if the cellular network is LTE, all data-carrying physical channels use SC-FDMA for D2D signaling. In D2D communication, user devices transmit data signals to each other over direct links using cellular resources, rather than through a radio base station. Throughout this disclosure, the terms "D2D," "ProSe," and "sidelink" are used interchangeably.

[0066] D2D communication in LTE focuses on two aspects: discovery and communication.

[0067] ProSe (Proximity-based Service) Direct Discovery is defined as a procedure used by a ProSe-enabled UE to discover other ProSe-enabled UEs within its close proximity using E-UTRA direct radio signals via the PC5 interface.

[0068] In D2D communication, users transmit data signals to each other via direct links using cellular resources, rather than through a base station (BS). D2D users communicate directly while remaining under the control of the BS (i.e., at least when within the coverage of the eNB). Therefore, D2D can improve system performance by reusing cellular resources.

[0069] D2D is assumed to operate in the uplink LTE spectrum (in the case of FDD) or in the uplink subframes of a given coverage cell (in the case of TDD, except when out of coverage). In addition, D2D transmission / reception does not use full-duplex on a given carrier. From the perspective of an individual UE, D2D signal reception and LTE uplink transmission on a given carrier do not use full-duplex, that is, D2D signal reception and LTE UL transmission cannot be performed simultaneously.

[0070] In D2D communication, when a specific UE1 has a transmitting role (transmitting user equipment or transmitting terminal), UE1 sends data, and another UE2 (receiving user equipment) receives it. UE1 and UE2 can change their transmitting and receiving roles. Transmissions from UE1 can be received by one or more UEs, such as UE2.

[0071] ProSe direct communication Layer 2 link

[0072] In short, ProSe direct one-to-one communication is achieved by establishing a secure Layer 2 link over PC5 between two UEs. Each UE has a Layer 2 ID for unicast communication, which is included in the source Layer 2 ID field of each frame sent by the UE on the Layer 2 link and in the destination Layer 2 ID of each frame received by the UE on the Layer 2 link. The UE needs to ensure that the Layer 2 ID used for unicast communication is at least locally unique. Therefore, the UE should be prepared to use unspecified mechanisms to handle Layer 2 ID conflicts with neighboring UEs (for example, self-allocating a new Layer 2 ID for unicast communication when a conflict is detected). The Layer 2 link used for one-to-one ProSe direct communication is identified by the combination of the Layer 2 IDs of the two UEs. This means that a UE can participate in multiple Layer 2 links for one-to-one ProSe direct communication using the same Layer 2 ID.

[0073] One-to-one ProSe direct communication includes the following procedures, as detailed in section 7.1.2 of TR 23.713 current version v13.0.0, which is incorporated herein by reference:

[0074] Establish a secure Layer 2 link on PC5.

[0075] IP address / prefix allocation.

[0076] Layer 2 link maintenance on PC5.

[0077] The Layer 2 link on PC5 is released.

[0078] Figure 3 The figure shows how to establish a secure Layer 2 link on the PC5 interface.

[0079] 1. UE-1 sends a Direct Communication Request message to UE-2 to trigger mutual authentication. The link initiator (UE-1) needs to know the Layer 2 ID of the peer (UE-2) in order to perform step 1. As an example, the link initiator can learn the Layer 2 ID of the peer by first performing a discovery procedure or by already participating in a ProSe one-to-many communication involving the peer.

[0080] 2. UE-2 initiates a mutual authentication process. Successful completion of the authentication process completes the establishment of a secure layer 2 link on PC5.

[0081] UEs participating in isolated (non-relayed) one-to-one communications may also use link-local addresses. The PC5 signaling protocol shall support keep-alive functionality, which is used to detect when a UE is out of ProSe communication range so that the UE can proceed with an implicit Layer 2 link release. Layer 2 link release over PC5 may be performed using a Disconnect Request message transmitted to the other UE, which also deletes all associated context data. Upon receiving the Disconnect Request message, the other UE responds with a Disconnect Response message and deletes all context data associated with the Layer 2 link.

[0082] ProSe direct communication related flags

[0083] The current version 13.3.0 of 3GPP TS 36.300 defines the following identifiers for ProSe direct communication in subsection 8.3:

[0084] · SL-RNTI : A unique identifier used for ProSe direct communication scheduling;

[0085] · Source Layer 2 ID : Identifies the sender of data in sidelink ProSe direct communication. The source Layer 2 ID is 24 bits long and is used together with the ProSe Layer 2 destination ID and LCID to identify the RLC UM entity and PDCP entity in the receiving unit;

[0086] · Destination Layer 2 ID : Identifies the destination of data in sidelink ProSe direct communication. The destination Layer 2 ID is 24 bits long and is split into two bit strings in the MAC layer:

[0087] ■ One bit string is the LSB portion (8 bits) of the destination Layer 2 ID and is forwarded to the physical layer as the Sidelink Control Layer 1 ID. This identifies the target of the intended data in Sidelink Control and is used to filter packets at the physical layer.

[0088] ■ The second bit string is the MSB part (16 bits) of the destination layer 2 ID and is carried within the MAC header. This is used to filter packets at the MAC layer.

[0089] Access stratum signaling is not required for group formation and configuration of the source Layer 2 ID, destination Layer 2 ID, and sidelink control L1 ID in the UE. These identifiers are provided by higher layers or derived from identifiers provided by higher layers. In the case of multicast and broadcast, the ProSe UE ID provided by higher layers is directly used as the source Layer 2 ID, and the ProSe Layer 2 group ID provided by higher layers is directly used as the destination Layer 2 ID in the MAC layer. In the case of one-to-one communication, higher layers provide the source Layer 2 ID and destination Layer 2 ID.

[0090] Radio resource allocation for short range services

[0091] From the transmitting UE’s perspective, a proximity services-enabled UE (ProSe-enabled UE) can operate in two modes for resource allocation:

[0092] Mode 1 refers to eNB-scheduled resource allocation, where the UE requests transmission resources from the eNB (or Release 10 relay node), and the eNodeB (or Release 10 relay node) in turn schedules resources used by the UE to transmit direct data and direct control information (e.g., scheduling assignments). The UE needs to be RRC_CONNECTED in order to transmit data. Specifically, the UE sends a scheduling request (D-SR or random access) to the eNB in ​​the usual way, followed by a buffer status report (BSR) (see also the section "Transmission procedure for D2D communication" below). Based on the BSR, the eNB can determine that the UE has data for ProSe direct communication transmission and can estimate the resources required for the transmission.

[0093] Mode 2, on the other hand, refers to UE autonomous resource selection, where the UE selects resources (time and frequency) from a resource pool by itself for the transmission of direct data and direct control information (i.e. SA). One resource pool is defined, for example, by the content of SIB18 (i.e. by the field commTxPoolNormalCommon), this specific resource pool is broadcast in the cell and is then commonly available to all UEs in the cell that are still in RRC_Idle state. Effectively, the eNB can define up to four different instances of the pool, four resource pools for the transmission of SA messages and direct data, respectively. However, in Release 12, the UE shall always use the first resource pool defined in the list, even if it is configured with multiple resource pools. For Release 13 this restriction is removed, i.e. the UE can transmit on multiple configured resource pools within one SC period. How the UE selects the resource pool for transmission is further outlined below (and further specified in TS 36.321).

[0094] As an alternative, another resource pool may be defined by the eNB and signaled in SIB18 (ie by using the field commTxPoolExceptional) which may be used by the UE in exceptional cases.

[0095] The resource allocation mode that the UE will use can be configured by the eNB. In addition, the resource allocation mode that the UE will use for D2D data communication may also depend on the RRC state (i.e., RRC_IDLE or RRC_CONNECTED), and the coverage state of the UE (i.e., in coverage, out of coverage). If the UE has a serving cell (i.e., the UE is RRC_CONNECTED or camped on a cell in RRC_IDLE), the UE is considered to be in coverage.

[0096] Figure 4 The usage of transmit / receive resources for overlay (LTE) and underlay (D2D) systems is illustrated.

[0097] Basically, the eNodeB controls whether the UE can apply Mode 1 or Mode 2 transmission. Once the UE knows its resources where it can send (or receive) D2D communication, the UE will only use the corresponding resources for the corresponding transmission / reception. Figure 4 In the D2D subframe, the D2D subframe will only be used to receive or send D2D signals. Since the UE as a D2D device operates in half-duplex mode, the UE can receive or send D2D signals at any time point. Similarly, Figure 4 Other subframes illustrated in may be used for LTE (coverage) transmission and / or reception.

[0098] Transmission process for D2D communication

[0099] The D2D data transmission procedure differs depending on the resource allocation mode. As described above for Mode 1, the eNB explicitly schedules resources for scheduling allocation and D2D data communication following a corresponding request from the UE. Specifically, the eNB can inform the UE that D2D communication is generally allowed, but that Mode 2 resources (i.e., resource pools) are not provided; this can be done, for example, by an exchange of a D2D communication interest indication of the UE and a corresponding response (D2D Communication Response), where the corresponding exemplary ProseCommConfig information element will not include commTxPoolNormalCommon, meaning that a UE that wants to start direct communication involving transmissions must request the E-UTRAN to allocate resources for each individual transmission. Therefore, in this case, the UE has to request resources for each individual transmission, and below, the different steps of the request / grant procedure are exemplarily listed for this Mode 1 resource allocation:

[0100] Step 1: The UE sends a Scheduling Request (SR) to the eNB via the PUCCH.

[0101] Step 2: The eNB grants UL resources (for the UE to send BSR) via PDCCH scrambled by the C-RNTI.

[0102] Step 3: The UE sends a D2D BSR indicating the buffer status via PUSCH.

[0103] Step 4: The eNB grants D2D resources (for the UE to send data) via the PDCCH scrambled by the D2D-RNTI.

[0104] • Step 5: The D2D Tx UE transmits SA / D2D data according to the grant received in step 4.

[0105] A Scheduling Assignment (SA), also known as SCI (Sidelink Control Information), is a compact (low payload) message containing control information, such as a pointer to the time-frequency resources for the corresponding D2D data transmission, the modulation and coding scheme, and the group destination ID. The SCI conveys sidelink scheduling information for one (ProSE) destination ID. The content of the SA (SCI) is essentially based on the grant received in step 4 above. The D2D grant and the SA content (i.e., the SCI content) are defined in subsection 5.4.3 of the current version 13.1.0 of the 3GPP technical standard 36.212, incorporated herein by reference. Subsection 5.4.3 specifically defines SCI format 0 (see the content of SCI format 0 above).

[0106] On the other hand, for Mode 2 resource allocation, the above steps 1-4 are basically not necessary, and the UE autonomously selects resources for SA and D2D data transmission from a transmission resource pool configured and provided by the eNB.

[0107] Figure 5 Scheduling assignments and transmission of D2D data for two UEs (UE-1 and UE-2) are exemplarily illustrated, wherein resources for sending the scheduling assignments are periodic, and resources for D2D data transmission are indicated by the corresponding scheduling assignments.

[0108] Figure 6 The D2D communication timing for Mode 2 (autonomous scheduling) during one SA / data period (also called SC period, sidelink control period) is illustrated. Figure 7 The diagram shows the D2D communication timing for Mode 1 (eNB scheduled assignment) during one SA / data period. The SC period is the time period that includes the transmission of the scheduled assignment and its corresponding data. Figure 6 As can be seen in the figure, the UE uses the transmission pool resources SA_Mode2_Tx_pool for mode 2 scheduling allocations to transmit scheduling allocations after the SA offset time. For example, the first transmission of SA is followed by three retransmissions of the same SA message. The UE then starts D2D data transmission at a configured offset (Mode2data_offset) after the first subframe of the SA resource pool (given by SA_offset), i.e., more specifically the T-RPT bitmap / pattern. One D2D data transmission of a MAC PDU (i.e., transport block) consists of its first initial transmission and several retransmissions. In order to Figure 6 (and Figure 7 ), assuming three retransmissions (i.e., the second, third, and fourth transmissions of the same MAC PDU). The Mode 2 T-RPT bitmap (Time Resource Mode for Transmission, T-RPT) essentially defines the timing of a MAC PDU transmission (the first transmission) and its retransmissions (the second, third, and fourth transmissions). The SA mode essentially defines the timing of the initial transmission of an SA and its retransmissions (the second, third, and fourth transmissions).

[0109] As currently specified in the standards, for one sidelink grant, for example, sent by the eNB or selected by the UE itself, the UE can transmit multiple transport block MAC PDUs (only one per subframe (TTI), i.e., one after another), but only to one ProSe destination group. Furthermore, the retransmission of one transport block must be completed before the first transmission of the next transport block begins, i.e., only one HARQ process is used per sidelink grant for the transmission of multiple transport blocks. Furthermore, the UE can have and use multiple sidelink grants per SC period, but select a different ProSe destination for each of them. Thus, in one SC period, the UE can transmit data to one ProSe destination only once.

[0110] As from Figure 7 As is evident from the example, for the resource allocation mode scheduled by the eNB (Mode 1), D2D data transmission, i.e. more specifically the T-RPT mode / bitmap, starts in the next UL subframe after the last SA transmission repetition in the SA resource pool. Figure 6 As illustrated, the Mode 1 T-RPT bitmap (Time Resource Pattern of Transmission, T-RPT) basically defines the timing of a MAC PDU transmission (first transmission) and its retransmissions (second, third and fourth transmissions).

[0111] The sidelink data transmission procedure can be found in section 5.14 of 3GPP standard document TS 36.321 v13.2.0, which is incorporated herein by reference. Therein, Mode 2 autonomous resource selection is described in detail, distinguishing between being configured with a single radio resource pool or multiple radio resource pools.

[0112] The above discussion is about the current state of the 3GPP standards for D2D communications. However, it should be noted that there are ongoing discussions on how to further improve and enhance D2D communications, which may lead to changes to D2D communications in future releases. The present invention, which will be described later, should also be applicable to those later releases.

[0113] For example, for 3GPP Release 14, which is currently under development, 3GPP may decide to change the transmission timing so that it is no longer based on the SC cycle as described above, but is different thereto (e.g., based on the same / similar subframes as the Uu interface transmission). Accordingly, the above detailed example of how transmission on the sidelink (PC5) interface can be performed is merely exemplary and may be applicable to Release 13, but may not be applicable to subsequent releases corresponding to the 3GPP standard.

[0114] Furthermore, in future versions of the D2D framework, especially those related to vehicular communications, T-RPT may no longer be used.

[0115] ProSe network architecture and ProSe entities

[0116] Figure 8 A high-level exemplary architecture for a non-roaming scenario is illustrated, including different ProSe applications in respective UEs A and B, as well as a ProSe application server and ProSe functions in the network. Figure 8 The example architecture is taken from TS 23.303 v.13.2.0 Chapter 4.2 "Architectural Reference Model", which is incorporated herein by reference.

[0117] The functional entities are presented and described in detail in TS 23.303 subsection 4.4 “Functional Entities”, which is incorporated herein by reference. The ProSe function is a logical function that is used for network-related actions required for ProSe and plays different roles for each feature of ProSe. The ProSe function is part of 3GPP's EPC and provides all relevant network services related to short distance services, such as authorization, authentication, data processing, etc. For ProSe direct discovery and communication, the UE can obtain a specific ProSe UE identity, other configuration information, and authorization from the ProSe function through the PC3 reference point. Multiple ProSe functions can be deployed in the network, but for ease of illustration, a single ProSe function is presented. The ProSe function includes three main sub-functions that perform different roles depending on the ProSe feature: Direct Provisioning Function (DPF), Direct Discovery Name Management Function, and EPC-level Discovery Function. The DPF is used to provide the UE with the necessary parameters for using ProSe direct discovery and ProSe direct communication.

[0118] The term “UE” used in this connection refers to a ProSe-enabled UE that supports ProSe functionality such as:

[0119] ProSe control information is exchanged between the ProSe-enabled UE and the ProSe function over the PC3 reference point.

[0120] • Procedure for Open ProSe Direct Discovery of other ProSe-enabled UEs over the PC5 reference point.

[0121] Procedures for one-to-many ProSe direct communication over the PC5 reference point.

[0122] The process of acting as a ProSe UE-to-network relay. The remote UE communicates with the ProSe UE-to-network relay over the PC5 reference point. The ProSe UE-to-network relay uses Layer 3 packet forwarding.

[0123] Control information is exchanged between ProSe UEs over the PC5 reference point, e.g., for UE-to-network relay detection and ProSe direct discovery.

[0124] ProSe control information is exchanged between another ProSe-enabled UE and the ProSe function over the PC3 reference point. In the case of ProSe UE-to-network relay, the remote UE will send this control information over the PC5 user plane to relay to the ProSe function over the LTE-Uu interface.

[0125] Configuration of parameters (e.g., including IP address, ProSe Layer 2 group ID, group security material, radio resource parameters). These parameters can be pre-configured in the UE or, if in coverage, can be signaled to the ProSe function in the network over the PC3 reference point.

[0126] The ProSe application server supports the storage of EPC ProSe user IDs, ProSe function IDs, and the mapping of application layer user IDs and EPC ProSe user IDs. The ProSe application server (AS) is an entity outside the scope of 3GPP. The ProSe application in the UE communicates with the ProSe AS via the application layer reference point PC1. The ProSe AS is connected to the 3GPP network via the PC2 reference point.

[0127] Vehicle-to-everything (V2X) services

[0128] A new study item has been set up in 3GPP in Release 14, considering the usefulness of new LTE features for the automotive industry - including Proximity Services (ProSe) and LTE-based broadcast services. The ProSe features described above are therefore considered to provide a good basis for V2X services. Changes to the D2D framework were discussed regarding how to enhance the transmission of vehicular communications. For example, the T-RPT mode may no longer be used. In addition, frequency division multiplexing can be foreseen instead of or in addition to the use of TDD for transmitting data and SA as described above. Collaborative services in vehicular scenarios are becoming crucial for future connected vehicles in the ITS (Intelligent Transport Systems) research area. These collaborative services should reduce road traffic fatalities, increase road capacity, reduce the carbon footprint of road transport, and improve the user experience during driving.

[0129] V2X communication is the transfer of information from a vehicle to any entity that may affect the vehicle, and vice versa. This information exchange can be used to improve safety, mobility, and environmental applications, including driver assistance vehicle safety, speed adaptation and warnings, emergency response, driving information, navigation, traffic operations, commercial fleet planning, and payment transactions.

[0130] LTE support for V2X services includes three different use cases:

[0131] V2V: Covers LTE-based communications between vehicles.

[0132] V2P: covers LTE-based communications between vehicles and devices carried by individuals (e.g., handheld devices carried by pedestrians, cyclists, drivers, or passengers).

[0133] V2I: Covers LTE-based communications between vehicles and roadside units.

[0134] These three types of V2X can use "cooperative awareness" to provide smarter services to end users. This means that transportation entities (such as vehicles, roadside infrastructure, and pedestrians) can collect knowledge of their local environment (such as information received from nearby vehicles or sensor equipment), process and share this knowledge to provide smarter services (such as cooperative collision warning or autonomous driving).

[0135] Regarding V2V communications, E-UTRAN allows (vehicle) UEs in close proximity to each other to exchange V2V-related information using E-UTRA(N) when permission, authorization, and proximity criteria are met. The proximity criteria can be configured by the MNO (Mobile Network Operator). However, UEs supporting V2V services can exchange this information when served by or not served by E-UTRAN supporting V2X services.

[0136] Devices supporting V2V applications (vehicle UEs) transmit application layer information (e.g., about their location, dynamics, and attributes as part of the V2V service). The V2V payload must be flexible to accommodate different information contents, and information can be transmitted periodically according to the configuration provided by the MNO.

[0137] V2V is primarily broadcast-based; V2V includes the exchange of V2V-related application information directly between unique devices, and / or the exchange of V2V-related application information between unique devices via infrastructure supporting V2X services (e.g., RSUs, application servers, etc.) due to the limited direct communication range of V2V.

[0138] With respect to V2I communications, a device supporting a V2I application sends application layer information to a roadside unit, which in turn may send the application layer information to a group of devices or devices supporting the V2I application.

[0139] V2N (Vehicle to Network, eNB / CN) is also introduced, in which one party is a UE and the other party is a serving entity, both of which support V2N applications and communicate with each other via an LTE network.

[0140] Regarding V2P communication, E-UTRAN allows UEs in close proximity to exchange V2P-related information using E-UTRAN when permission, authorization, and proximity criteria are met. The proximity criteria can be configured by the MNO. However, UEs supporting V2P services can exchange this information even when not served by E-UTRAN supporting V2X services.

[0141] UEs supporting V2P applications transmit application layer information. This information can be broadcast by vehicles with UEs supporting V2X services (e.g., to alert pedestrians) and / or by pedestrians with UEs supporting V2X services (e.g., to alert vehicles).

[0142] V2P includes the exchange of V2P-related application information directly between unique UEs (one for vehicles and the other for pedestrians), and / or the exchange of V2P-related application information between unique UEs via infrastructure supporting V2X services (e.g., RSUs, application servers, etc.) due to the limited direct communication range of V2P.

[0143] For this new study item V2X, 3GPP has already provided specific sections and definitions in TR 21.905 current version 13.0.0, which can be reused for this application.

[0144] Roadside Unit (RSU): An entity that supports V2I services that can be sent to and received from UEs using V2I applications. An RSU can be implemented in an eNB or a fixed UE.

[0145] V2I service: A type of V2X service in which one party is a UE and the other party is an RSU, both using a V2I application.

[0146] V2N service: A type of V2X service in which one party is a UE and the other party is a service entity, and the two parties communicate with each other using a V2N application and via an LTE network entity.

[0147] V2P service: A type of V2X service in which the two communicating parties are UEs using V2P applications.

[0148] V2V service: A type of V2X service in which the two communicating parties are UEs using V2V applications.

[0149] V2X service: A type of communication service that involves transmitting or receiving UEs using V2V applications via 3GPP transmission. Based on the other party involved in the communication, it can be further divided into V2V service, V2I service, V2P service and V2N service.

[0150] Many ITS services have common communication requirements:

[0151] Periodic status exchange. ITS services usually require knowledge of the status of vehicles or roadside terminals. This means the periodic exchange of data packets with information about location, speed, identifiers, etc.

[0152] Asynchronous notifications. These messages are used to notify of specific service events. Unlike previous status messages, reliable delivery of these messages to a single endpoint or a group of endpoints is often a key requirement.

[0153] Examples of the first communication type can be found in traffic efficiency services (such as remote vehicle monitoring), which aggregate periodic status data from vehicles, or safety services (such as cooperative collision avoidance), which require motion information about surrounding vehicles to detect potential impacts. Asynchronous notifications are primarily found in safety services, such as slippery road or post-collision warnings.

[0154] Different types of messages are defined and will be defined for V2V communication. ETSI has defined two different types of messages for Intelligent Transport Systems (ITS), see the corresponding European standards ETSI EN 302637-2v1.3.1 and ETSI EN 302637-3v 1.2.1:

[0155] • Collaborative Awareness Messages (CAMs), which are continuously triggered by vehicle dynamics to reflect vehicle status.

[0156] Decentralized Environmental Notification Message (DENM), which is triggered only when a vehicle-related safety event occurs.

[0157] Since V2V and ITS standardization is just beginning, it is expected that other messages may be defined in the future.

[0158] ITS-stations (ITS-Ss) continuously (periodically) broadcast CAM messages to exchange status information with other ITS-Ss. Therefore, CAM messages have a greater impact on traffic load than event-triggered (aperiodic) DENM messages. Essentially, CAM messages are heartbeat messages periodically broadcast by each vehicle to its neighbors, providing information on presence, location, temperature, and basic status. In contrast, DENM messages are event-triggered messages broadcast to warn road users of hazardous events. Therefore, the service characteristics of the CAM messages defined by ETSI for ITS are considered more representative of V2V traffic.

[0159] Collaborative Awareness Messages (CAMs) are messages exchanged in an ITS network between ITS-Ss to create and maintain mutual awareness and support collaborative performance of vehicles using the road network. Point-to-multipoint communication should be used to transmit CAMs so that the CAMs are transmitted from the originating ITS-S to the receiving ITS-S located in the direct communication range of the originating ITS-S. CAM generation should be triggered and managed by a Collaborative Awareness Basic Service that defines the time interval between two consecutive CAM generation. Currently, the upper and lower limits of the transmission interval are 100ms (i.e., a CAM generation rate of 10Hz) and 1000ms (i.e., a CAM generation rate of 1Hz). The underlying philosophy of ETSI ITS is to send CAMs when there is new information to share (e.g., a new position, new acceleration, or a new heading value). Accordingly, when the vehicle is moving slowly and at a constant heading and speed, a high CAM generation rate does not bring real benefits because the CAMs only show minimal differences. The transmission frequency of a vehicle's CAM varies between 1 Hz and 10 Hz depending on vehicle dynamics (e.g., speed, acceleration, and heading). For example, the slower a vehicle travels, the fewer CAMs are triggered and transmitted. Vehicle speed is the primary factor affecting CAM traffic generation.

[0160] In the above, periodic collaboration awareness messages have been described. However, it should be noted that while some of the above information has been standardized, other information, such as periodicity and message size, has not yet been standardized and is based on assumptions. Furthermore, standardization may change in the future, and therefore aspects of how CAMs are generated and transmitted may also change.

[0161] To ensure that the vehicle UE has radio resources for transmitting CAM on the sidelink, as described above, Mode 1 and / or Mode 2 radio resource allocation is envisioned. With Mode 1 radio resource allocation, the eNB allocates resources for SA messages and data for each SA cycle. However, when there is a large amount of traffic (e.g., high-frequency periodic traffic), the overhead on the Uu link from the UE to the eNB can be significant.

[0162] As is apparent from the above, many V2V traffic is periodic, so that 3GPP has agreed that for sidelink V2V communication Mode 1 (ie, eNB-scheduled radio resource allocation), the eNB and UE will support sidelink semi-persistent radio resource allocation.

[0163] Support for sensing mechanisms and semi-persistent transmissions is agreed upon to assist with autonomous resource control / selection mechanisms for the V2X sidelink. A UE will indicate within the PSCCH (SA / SCI) that it has data regarding a selected set of periodic resources until resource selection occurs. This resource reservation information (signaled within the SCI) can be used by other UEs intending to transmit V2X messages for resource selection, eliminating the need to consider resources already reserved / reserved by other UEs for radio resource selection. This resource reservation / reservation process is particularly suitable for services whose packets arrive at a specific period, such as CAM messages.

[0164] The indication of reserved radio resources in the scheduling information as described above can be monitored ("sensed") by other (vehicle) devices. In general, the sensing process collects information about radio resources, thereby allowing predictions to be made about future radio resources that can be used in the resource allocation process to identify a set of resource candidates for transmission. 3GPP has agreed on very few things, but it can be assumed that the sensing process classifies time-frequency resources into:

[0165] "Unavailable" resources. These are resources on which the UE is not allowed to transmit because they have already been booked / reserved by other UEs, and

[0166] • “Candidate (or available) resources.” These are resources on which the UE might / can perform transmissions.

[0167] In addition, the 3GPP agreement also performs energy measurement on the sensing process, although the agreement does not provide any details on how to perform the energy measurement and what energy measurement will be performed. Therefore, energy-based sensing can be understood as the process by which the UE measures the received signal strength on the PSSCH radio resource and / or PSCCH radio resource. Energy-based sensing can basically help identify relatively close-range interference sources as well as distant interference sources.

[0168] Furthermore, it is discussed whether to indicate the priority of data (or corresponding radio resource reservation) in the Scheduling Assignment (SCI) so that the priority can be used in the resource allocation process, although there is no agreement on how to use the priority effectively.

[0169] Another topic that emerged during the discussion was the use of a channel's (i.e., PC5 interface's) congestion level for the resource allocation process, which may be similar to the Channel Busy Ratio (CBR) known from ETSI standards (see, for example, ETSI EN 302 571 v 2.0.0 and 102 687 v 1.1.1). Again, no details were discussed in this regard, let alone an agreement on how exactly to use such a congestion level.

[0170] The sensing should be implemented in a simple way so as not to increase the complexity of the UE too much.It should also be noted that there may be multiple ways / options on how to implement the sensing algorithm.

[0171] While general agreement has been reached regarding sensing and resource reservation for V2X transmissions over the PC5 interface, implementing these mechanisms into current systems can lead to problems and inefficiencies. Summary of the Invention

[0172] Non-limiting and exemplary embodiments provide an improved UE autonomous radio resource allocation procedure for data transmission over a sidelink interface. The independent claims provide non-limiting and exemplary embodiments. Advantageous embodiments are subject to the dependent claims.

[0173] According to a first aspect, a transmitting device is provided for determining radio resources for the transmission of data (e.g., vehicle periodic or non-periodic data) via a sidelink interface to other devices. It is assumed that the transmitting device continuously performs a resource sensing process to obtain information about future radio resources. According to one example, radio resource sensing includes at least monitoring scheduled allocations transmitted by other devices that announce and / or reserve radio resources at a later point in time. The reserved radio resources can then be excluded from the radio resource selection. Sensing can also include measuring the received signal energy in the radio resources. In the future, other information may also be collected during sensing. However, it should be noted that the sensing process is not performed in the subframes in which the device performs transmission, because the device cannot perform receiving and transmitting operations simultaneously.

[0174] It is assumed that data becomes available for transmission at a specific time and the device proceeds to perform a UE-autonomous resource allocation process in order to determine the relevant transmission parameters, including the actual frequency-time radio resources to be used for data transmission. A transmission window can be defined as starting from the point at which data becomes available, within which transmission (and possible retransmissions) should be completed, for example in order to meet the latency requirements of the data. On the other hand, a sensing window can be defined as a period of time before data becomes available, during which sensing operations obtain information about the radio resources in the transmission window. During the radio resource allocation process, the vehicle UE autonomously determines the transmission parameters and selects radio resources in order to perform data transmission within the transmission window.

[0175] Based on the results of the sensing process, radio resource selection distinguishes between primary and secondary subframes within the transmission window. Secondary subframes are those subframes within the transmission window whose resource sensing process provides less information than possible because, in at least one subframe within the sensing window corresponding to a secondary subframe, the vehicle UE performs a transmission and is therefore unable to perform a resource sensing process. In contrast, primary subframes are those subframes within the transmission window where the resource sensing process performed by the vehicle UE collects all possible information because it performs the resource sensing process in all corresponding subframes within the sensing window. For example, a resource sensing process not performed in subframe t within the sensing window will result in missing information in future subframes separated by a possible data transmission period interval. Exemplarily assuming a period of multiples of 100ms, with a minimum of 100ms and a maximum of 1000ms, subframes t+100ms, t+200ms, t+300ms, ..., and t+1000ms (when within the vehicle UE's transmission window) will be considered secondary subframes.

[0176] The vehicle UE should preferably select radio resources from the primary subframe relative to radio resources from the secondary subframe. In the aspect, assuming that there are more than one possible radio resource candidates, the ranking of the radio resource candidates should be separate between the primary subframe and the secondary subframe, and the UE will select the highest ranked candidate for transmission of data. Alternatively, if the highest ranked candidate cannot be used (for example, resulting in a collision with other UEs), the second highest ranked candidate can be used, and so on. Such a ranking process can be performed in different ways. It is advantageous to use the time delay between the radio resource candidate and the data arrival time and the energy prediction obtained for the radio resource candidate during the sensing process for ranking the candidates. Radio resource candidates that cause short time delays are better than those that cause longer delays. On the other hand, radio resource candidates with low energy predictions are better than radio resource candidates for which the sensing process predicts high transmission energy.

[0177] Although energy prediction can be performed using measurements in all subframes of the sensing window, another variant improves the energy prediction for a specific radio resource candidate by considering only those subframes that are relevant to the subframe of the radio resource candidate, the relevance being based on the possible periodicity of the data, i.e. -100ms, -200ms, -300ms, ..., -1000ms as described above.

[0178] According to another aspect, the selection and transmission of radio resources for the scheduling allocation performed by the vehicle UE is improved in a similar manner to that performed for data transmission. Accordingly, radio resource reservation can be performed for the transmission of the scheduling allocation, and the vehicle UE performs a radio resource sensing process, the result of which can be used for radio resource selection for the scheduling allocation transmission. Resource reservation for the scheduling allocation can be implemented separately or jointly with the radio resource reservation for data. When implemented together with the data resource reservation, the vehicle UE reserves radio resources for both the data and the scheduling allocation, or for neither. A corresponding indication can be provided in the scheduling allocation so that the receiving entity is informed that the received scheduling allocation also reserves radio resources for one or more future transmissions of the scheduling allocation and / or data.

[0179] The radio resource selection process performed for scheduled assignment transmissions can also distinguish between primary and secondary subframes, as discussed above for data transmissions. The corresponding results of the sensing process are used in this regard to distinguish between subframes within the transmission window for which the resource sensing process acquired all possible information (resulting in primary subframes) or subframes for which it did not (resulting in secondary subframes). An unsensed subframe t within the sensing window results in secondary subframes at t+100ms, t+200ms, t+300ms, ..., t+1000ms. Similarly, resources from the primary subframe should be preferred over resources in the secondary subframes for the selection process for scheduled assignment transmissions. The ranking process for candidates within the primary and secondary subframes is performed separately from each other. The actual ranking process for resource candidates for scheduled assignment transmissions can be performed in the same manner as discussed above for ranking resource candidates for data transmissions. For example, radio resource candidates that incur a short delay are favored over those that incur a longer delay. On the other hand, radio resource candidates with low energy prediction are preferred over radio resource candidates for which the sensing process predicts high transmission energy.

[0180] Accordingly, in a general first aspect, the technology disclosed herein features a transmitting device for determining radio resources to be used for data transmission from the transmitting device to one or more receiving devices via a sidelink interface. A receiving unit and a processing unit of the transmitting device perform a resource sensing process to obtain information about radio resources that the transmitting device can use to transmit data at a later point in time. After data becomes available for transmission, the processing unit performs autonomous radio resource allocation to select radio resources to be used for data transmission within a transmission window based on information obtained through the resource sensing process during a sensing window before the data becomes available for transmission. The autonomous radio resource allocation includes preferentially selecting radio resources in primary subframes of the transmission window relative to radio resources in secondary subframes of the transmission window. Secondary subframes in the transmission window correspond to those subframes in the sensing window for which the transmitting device did not perform the resource sensing process, and primary subframes in the transmission window correspond to those subframes in the sensing window for which the transmitting device did perform the resource sensing process.

[0181] Accordingly, in a general first aspect, the technology disclosed herein features a method for a transmitting device for determining radio resources to be used for data transmission from the transmitting device to one or more receiving devices via a sidelink interface. The method includes: performing a resource sensing procedure by the transmitting device to obtain information about radio resources available for the transmitting device to transmit data at a later point in time. After data becomes available for transmission, the transmitting device performs autonomous radio resource allocation to select radio resources to be used for data transmission within a transmission window based on information obtained through the resource sensing procedure during a sensing window before the data becomes available for transmission. The autonomous radio resource allocation includes preferentially selecting radio resources in primary subframes of the transmission window relative to radio resources in secondary subframes of the transmission window. Secondary subframes in the transmission window correspond to those subframes in the sensing window for which the transmitting device did not perform the resource sensing procedure, and primary subframes in the transmission window correspond to those subframes in the sensing window for which the transmitting device did perform the resource sensing procedure.

[0182] Accordingly, in a general first aspect, the technology disclosed herein features a transmitting device for transmitting a scheduling assignment and data to one or more receiving devices via a sidelink interface. A receiving unit and a processing unit of the transmitting device perform a resource sensing process to obtain information about radio resources that the transmitting device can use to transmit the scheduling assignment at a later point in time. After first data becomes available for transmission, the processing unit performs an autonomous radio resource allocation process to select radio resources within a transmission window for transmitting the first data based on the information obtained by the resource sensing process during a sensing window, and select radio resources within a transmission window for transmitting the first scheduling assignment, the sensing window preceding the first data becoming available for transmission. The first scheduling assignment includes information about the selected radio resources within the transmission window for transmitting the first data. The transmitting unit of the transmitting device transmits the first scheduling assignment using the selected radio resources and transmits the first data using the selected radio resources. The first scheduling assignment also indicates reserved radio resources of a second scheduling assignment that can be used by the transmitting device at a later point in time to transmit second data.

[0183] Accordingly, in a general first aspect, the technology disclosed herein features a method for a transmitting device for transmitting a scheduling assignment and data to one or more receiving devices via a sidelink interface. The method includes performing a resource sensing procedure to obtain information regarding radio resources available for the transmitting device to transmit the scheduling assignment at a later point in time. After first data becomes available for transmission, the method includes performing an autonomous radio resource allocation procedure to select radio resources within a transmission window for transmitting the first data based on the information obtained by the resource sensing procedure during a sensing window, and to select radio resources within a transmission window for transmitting the first scheduling assignment, the sensing window preceding the first data becoming available for transmission. The first scheduling assignment includes information regarding the selected radio resources within the transmission window for transmitting the first data. The method then includes transmitting the first scheduling assignment using the selected radio resources, and transmitting the first data using the selected radio resources. The first scheduling assignment also indicates reserved radio resources of a second scheduling assignment that can be used by the transmitting device to transmit second data at a later point in time.

[0184] According to a second aspect, a transmitting device is provided for determining radio resources to be used for data transmission from the transmitting device to one or more receiving devices via a sidelink interface, wherein the transmitting device includes: a receiving unit and a processing unit, which performs a resource sensing process to select radio resources that the transmitting device can use to transmit data at a later point in time, after the data transmission is triggered, the processing unit performs autonomous radio resource allocation to select radio resources to be used for data transmission within the transmission window based on the results of the resource sensing process during the sensing window before the data transmission is triggered, and wherein the autonomous radio resource allocation includes selecting radio resources in a primary subframe of the transmission window relative to radio resources in a secondary subframe of the transmission window, and wherein the secondary subframes in the transmission window correspond to those subframes in the sensing window in which the transmitting device did not perform the resource sensing process, and the primary subframes in the transmission window correspond to those subframes in the sensing window in which the transmitting device performed the resource sensing process; wherein the transmission window starts after the data transmission is triggered.

[0185] According to a third aspect, a method for a transmitting device is provided, the transmitting device being used to determine radio resources to be used for data transmission from the transmitting device to one or more receiving devices via a sidelink interface, wherein the method includes the following steps performed by the transmitting device: performing a resource sensing process to select radio resources that the transmitting device can use to transmit data at a later point in time, and after the data transmission is triggered, performing autonomous radio resource allocation to select radio resources to be used for data transmission within the transmission window based on the results of the resource sensing process during the sensing window before the data transmission is triggered, wherein the autonomous radio resource allocation includes selecting radio resources in a primary subframe of the transmission window relative to radio resources in a secondary subframe of the transmission window, and wherein the secondary subframes in the transmission window correspond to those subframes in the sensing window in which the transmitting device did not perform the resource sensing process, and the primary subframes in the transmission window correspond to those subframes in the sensing window in which the transmitting device performed the resource sensing process; wherein the transmission window starts after data becomes available.

[0186] According to a fourth aspect, an integrated circuit is provided that controls a process of a transmitting device for determining radio resources to be used for data transmission from the transmitting device to one or more receiving devices via a sidelink interface, wherein the process includes the following process performed by the transmitting device: performing a resource sensing process to select radio resources available to the transmitting device for transmitting data at a later point in time, after the data transmission is triggered, selecting radio resources to be used for transmitting data within the transmission window based on the results of the resource sensing process during the sensing window before the data transmission is triggered, wherein the autonomous radio resource allocation includes selecting radio resources in a primary subframe of the transmission window relative to radio resources in a secondary subframe of the transmission window, and wherein the secondary subframes in the transmission window correspond to those subframes in the sensing window in which the transmitting device did not perform the resource sensing process, and the primary subframes in the transmission window correspond to those subframes in the sensing window in which the transmitting device performed the resource sensing process; wherein the transmission window starts after the data transmission is triggered.

[0187] Additional benefits and advantages of the disclosed embodiments will be apparent from the description and drawings. Benefits and / or advantages may be provided individually by the various embodiments and features disclosed in the description and drawings, and need not be provided in full to obtain one or more of them.

[0188] These general and specific aspects may be implemented using systems, methods and computer programs, and any combination of systems, methods and computer programs. BRIEF DESCRIPTION OF THE DRAWINGS

[0189] Exemplary embodiments are described in more detail below with reference to the accompanying drawings.

[0190] Figure 1 shows an exemplary architecture of a 3GPP LTE system,

[0191] Figure 2 shows an exemplary downlink resource grid of a downlink time slot of a subframe as defined by 3GPP LTE (Release 8 / 9),

[0192] Figure 3 Schematically illustrates how a Layer 2 link for ProSe communication is established on PC5.

[0193] Figure 4 illustrates the use of transmit / receive resources for overlay (LTE) and underlay (D2D) systems,

[0194] Figure 5 The diagram shows the scheduling allocation and D2D data transmission of two UEs.

[0195] Figure 6 The figure shows the D2D communication timing of UE autonomous scheduling mode 2.

[0196] Figure 7 The figure shows the D2D communication timing of scheduling mode 1 scheduled by eNB.

[0197] Figure 8 An exemplary architecture model of ProSe for non-roaming scenarios is illustrated.

[0198] Figure 9 illustrates the frequency-time radio resources of a data resource pool of a vehicle UE divided into a transmission window and a sensing window at a time P when data becomes available for transmission,

[0199] Figure 10 illustrates frequency time radio resources of a data resource pool for vehicle UEs according to an exemplary implementation of the first embodiment, wherein subframes of a transmission window are classified as primary subframes or secondary subframes according to a sensing process,

[0200] Figure 11 is a sequence diagram of UE behavior according to an exemplary implementation of the first embodiment,

[0201] Figure 12 FIG1 illustrates frequency, time, and radio resources of a data resource pool for a vehicle UE according to an exemplary implementation of the first embodiment, and additionally illustrates an improved energy sensing process in a sensing window for radio resource candidates in a transmission window.

[0202] Figure 13 is a sequence diagram of UE behavior according to an exemplary implementation of the first embodiment, additionally illustrating the preemption process to be performed if no resources are found in the primary subframe and the secondary subframe,

[0203] Figure 14 yes Figure 13 The sequence diagram of the preemption process shown in

[0204] Figure 15 is a sequence diagram of UE behavior according to an exemplary implementation of the first embodiment, additionally illustrating the channel busy ratio discard function,

[0205] Figure 16 is a sequence diagram of UE behavior according to an exemplary implementation of the first embodiment, additionally illustrating a collision function for detecting a possible collision of SA and data transmission,

[0206] Figure 17 is a sequence diagram of UE behavior according to an exemplary implementation of the second embodiment, and

[0207] Figure 18The frequency-time radio resources of a scheduling allocation resource pool for vehicular UEs according to an exemplary implementation of the second embodiment are illustrated, wherein transmitted subframes are classified as primary subframes or secondary subframes according to a sensing process. DETAILED DESCRIPTION

[0208] A mobile station, mobile node, user terminal, or user equipment is a physical entity within a communication network. A node may have several functional entities. A functional entity is a software or hardware module that implements and / or provides a predetermined set of functions to other functional entities of the node or network. A node may have one or more interfaces that connect the node to a communication infrastructure or medium through which the node can communicate. Similarly, a network entity may have logical interfaces that connect the functional entity to a communication infrastructure or medium through which the network node can communicate with other functional entities or peer nodes.

[0209] The term "radio resources" used in the claims and application should be broadly understood to refer to physical radio resources such as time-frequency resources.

[0210] The term "direct communication transmission" as used in this application should be understood in a broad sense as a transmission directly between two user equipments, i.e. not via a radio base station (e.g. an eNB). Accordingly, a direct communication transmission is performed via a "direct sidelink connection", which is a term used for a connection established directly between two user equipments. For example, in 3GPP, the terms D2D (device-to-device) communication or ProSe communication or sidelink communication are used. The terms "direct sidelink connection", "sidelink interface" should be understood in a broad sense and may be understood in the 3GPP context as the PC5 interface described in the background section.

[0211] The term "ProSe" or its unabbreviated form "Proximity Services" is used in this application in the context of proximity-based applications and services in LTE systems, as exemplified in the background section. Other terms such as "D2D" are also used in this context to refer to device-to-device communication for proximity services.

[0212] The term "vehicle mobile terminal" as used throughout this application is to be understood in the context of the new 3GPP study item, respectively, the work item V2X (Vehicle to Everything) described in the background section. Accordingly, a vehicle mobile terminal should be broadly understood as a mobile terminal specifically installed in a vehicle (e.g., a car, commercial truck, motorcycle, etc.) to perform vehicle communication (i.e., to transmit vehicle-related information to other entities (such as vehicles, infrastructure, pedestrians), for example, for safety or driver assistance purposes. Optionally, the vehicle mobile terminal may have access to information available in a navigation system (assuming it is also installed in the car), such as map information, etc.

[0213] The term "autonomous radio resource allocation" (as opposed to "radio base station controlled radio resource allocation") as used throughout the application can be understood exemplarily in the context of 3GPP short distance services that allow two modes of resource allocation; namely, mode 1 (i.e., radio base station controlled radio resource allocation), according to which the radio base station controls the allocation; and mode 2 (i.e., autonomous radio resource allocation), according to which the terminal (or transmitting device) autonomously selects resources (without the need for a radio base station).

[0214] As explained in the background section, 3GPP has introduced a new study item for LTE-assisted vehicular communications, which should be based on ProSe procedures to exchange V2V services between various vehicular mobile terminals and other stations. In addition, V2X services should support a semi-persistent radio resource allocation, and it has been agreed that mechanisms for radio resource reservation and sensing will be supported to the terminals—particularly for the UE autonomous resource allocation mode (also known as Mode 2). However, only general agreements have been reached on sensing and radio resource reservation, without providing details on how to implement sensing and radio resource reservation, or how to adjust other mechanisms to ensure effective and seamless operation.

[0215] For example, it is still unclear how the resource sensing mechanism should be implemented. More specifically, it is unclear how to calculate energy measurements and how to choose resources based on the sensing mechanism during Mode 2 radio resource allocation.

[0216] The following will refer to Figure 9 Describe a possible solution. Figure 9 The diagram shows the frequency-time radio resources of the data resource pool of the vehicle UE (usually a transmitting device). The frequency-time radio resources in the diagram are exemplarily shown in units of PRB pairs (physical resource block pairs, with one subframe having 12 subcarriers). Figure 9 is an exemplary and simplified diagram for illustrating the solution. It is assumed that data becomes available for transmission (i.e. a packet arrives) at time P and that the transmission of the data (possibly also including retransmissions) should be completed at time L, which is denoted as the transmission window and is dependent on the delay requirement of the data to be transmitted (e.g. 100 ms; L=P+100 ms). The results of the sensing process obtained within the sensing window (e.g. 1000 ms) before the arrival of the packet should be taken into account for the radio resource allocation process to be performed by the vehicle UE to select the frequency-time radio resources (and possibly other transmission parameters) for transmitting the data. It is assumed exemplarily that three (physical) resource block pairs are required for the transmission of the data (according to current standardization, the resource blocks should be consecutive).

[0217] One piece of information obtained from the sensing process is that certain radio resources in the transmission window have been reserved by other devices and should not be used by the vehicle UE; the corresponding squares are vertically striped. The remaining radio resource candidates (three consecutive resource block pairs) available for vehicle UE to transmit data in the complete transmission window are Figure 9 There are a total of six candidates in the transmission window, all of which may be ranked, for example, based on energy measurements performed during the sensing process in the sensing window.

[0218] In more detail, the energy (eg, received signal strength) across the entire sensing window may be measured for the relevant radio resource candidates. For example, it is assumed that the corresponding radio resource candidates are identified based on the energy measurement. Figure 9 The ranking is shown as 1 to 4. Accordingly, radio resource candidates 2 having the same corresponding frequency radio resource in the sensing window are ranked equally. The same applies to the two resource candidates 3 at the bottom of the figure. Figure 9 The corresponding radio resources of the sensing window where the measured energies are averaged to predict the energy of the radio resource candidate 2 are illustrated with diagonal stripes. Figure 9 The corresponding frequency-time radio resources in the sensing window for energy measurement of resource candidate 4 are indicated by horizontal stripes. Figure 9 , but the radio resources corresponding to candidates 1 and 3 in the sensing window also perform corresponding energy measurements and processing. Accordingly, the vehicle UE can then select the highest-ranked radio resource candidate (candidate 1 in this example) for transmitting data, e.g., the candidate with the lowest energy prediction.

[0219] The above provides possible solutions for implementing the sensing process and corresponding radio resource allocation.

[0220] An optional embodiment thereof relates to a situation where no radio resource candidates are available (for example, when too many radio resources are reserved by other devices). Therefore, the vehicle UE may have to select a radio resource candidate that collides with radio resources already reserved by other devices; this process may be expressed as "preemption". During the preemption process, the vehicle UE may randomly select a suitable radio resource from the reserved radio resources in the transmission window, or may select a suitable reserved radio resource with a relatively low received signal strength prediction. Alternatively, a priority is also indicated for the reserved radio resources, and the vehicle UE may select the reserved radio resource with the lowest priority.

[0221] However, there are several problems with the above solution. For example, the received signal strength prediction (transmission energy) for a specific radio resource candidate is based on the received signal strength measurement performed in the corresponding frequency radio resource in the entire sensing window, and therefore does not reflect the actual transmission situation in the subframe where the resource candidate is located. The energy measurements of the entire sensing window for the radio resource candidate in a specific subframe are averaged, which does not take into account that data and scheduling allocation transmissions usually occur periodically, that is, only in a specific subframe. In addition, as mentioned above, Figure 9 The illustrated radio resource selection results in a very late transmission opportunity, i.e., at the end of the transmission window, causing the vehicle UE and the receiving entity to wait a long time for data, increasing data latency. When using priorities during the preemption process as described above, the preempted UE (i.e., the UE whose resources collide with the selected radio resource candidate) may be located near the vehicle UE, causing severe interference "collision" transmissions between the two.

[0222] As explained in the background section, D2D transmissions via the sidelink interface do not use full-duplex but rather half-duplex, making simultaneous V2X transmission and reception impossible. Consequently, in subframes where a vehicle UE is transmitting (e.g., scheduling assignments and / or data), the vehicle UE cannot perform sensing procedures. It is unclear how these missed sensing opportunities affect the radio resource allocation procedures performed by the vehicle UE.

[0223] The inventors have conceived the following exemplary embodiments to alleviate the above-mentioned problems.

[0224] Specific implementations of various embodiments will be implemented within the broad specifications given by the 3GPP standards and described in part in the background section, with specific key features added as described in the following embodiments. It should be noted that the embodiments can be advantageously used, for example, in mobile communication systems, such as the 3GPP LTE-A (Release 10 / 11 / 12 / 13 / 14 or higher) communication systems described in the background section. However, the embodiments are not limited to their use in these specific exemplary communication networks.

[0225] The description should not be construed as limiting the scope of the present disclosure, but rather as examples to better understand the embodiments of the present disclosure. A skilled artisan will appreciate that the general principles of the present disclosure, as set forth in the claims, can be applied in various scenarios and in ways not explicitly described herein. Several assumptions have been made for illustrative purposes, however, these assumptions should not limit the scope of the following embodiments.

[0226] The various embodiments primarily provide a radio resource allocation process performed by a vehicle UE when transmitting data to one or more receiving devices. Other functionality (i.e., functionality that remains unchanged by the various embodiments) can remain exactly as described in the Background section, or can be modified without any consequences for the various embodiments. This can include, for example, other processes such as how the vehicle UE performs subsequent transmissions of data, or how various transmitting devices discover each other.

[0227] One example scenario in which various embodiments can be applied is V2X communication, as illustrated in the technical background section. Thus, the transmitting and receiving devices can be, for example, UEs in vehicles, roadside units, "normal" mobile terminals carried by pedestrians, and the like. Furthermore, the data can be (periodic) vehicle data, such as CAM messages, which should be continuously exchanged between various vehicle entities, and for which resource sensing procedures and semi-persistent resources have been discussed in 3GPP.

[0228] Although the following exemplary embodiments will be described in conjunction with such a V2X communication scenario for illustrative purposes, the present invention is not limited thereto.

[0229] First embodiment

[0230] Hereinafter, a first embodiment for solving the above-mentioned problems will be described in detail. Different implementations and modifications of the first embodiment will also be explained.

[0231] As described above, it is assumed, for example, that the vehicle UE is installed in a vehicle and is capable of performing vehicle communication based on the D2D framework as described in the background technology section of this application. Accordingly, vehicle data (e.g., periodic data and aperiodic data) should be transmitted by the vehicle UE to other entities, wherein the vehicle UE is interested in the data of the other entities.

[0232] It is assumed that the UE supports and primarily performs Mode 2 radio resource allocation and has been correctly configured with the necessary resource pools to be able to autonomously select radio resources for transmitting scheduling information as well as data via the PC5 (sidelink) interface.

[0233] The periodic data to be transmitted by the vehicle UE will be illustrated by the Collaboration Awareness Message (CAM) described in detail in the Background section. As explained in the Background section, sensing and radio resource reservation have been generally agreed by 3GPP to be included in future standard releases related to the transmission of periodic data. In particular, radio resource reservation on the transmitting side allows a "semi-persistent" radio resource allocation to be implemented, for example by reserving the same resources as those currently used, also for one or more later time instances to transmit other packets of periodic data. Therefore, in those later time instances, the vehicle UE does not have to perform resource selection / request (Mode 1 or Mode 2 resource allocation) again in order to be able to transmit periodic data. Radio resource reservation can be implemented in different embodiments and has not yet been fixed by 3GPP. For example, radio resources can be reserved for the next transmission instance or for a longer time period (i.e., not just the next transmission instance of periodic data). Scheduling information (SCI) transmitted together with the sidelink data identifies the radio resources used for transmission, thereby allowing the receiving entity to correctly receive and process / decode the sidelink data. The scheduling information may additionally be used to indicate radio resource reservation, for example, by indicating the time or period of the data so that the receiving entity can determine the time (eg, subframe) when the radio resources are reserved.

[0234] The vehicle UE should further continuously perform the radio sensing process as described in the background section in order to obtain information about future radio resources. This information can then be used during the mode 2 radio resource allocation process performed by the vehicle UE to select radio resources (and possible other transmission parameters) for transmitting data (and corresponding scheduling allocations). The sensing process includes decoding scheduling allocations transmitted by other devices in order to identify reserved radio resources. Optionally, the sensing process also includes energy measurement (e.g., received signal strength, RSSI) of the entire frequency resource for data transmission configured for the vehicle UE.

[0235] One potential implementation option for the resource sensing process is that each UE has a map with a prediction of frequency resources that spans, for example, 100 ms (e.g., at most 1 second) starting from the next subframe. Then, at the time P when a packet arrives in the buffer in the UE, the UE has prepared a mapping of all frequency resources for subframes P to L (which may be called the transmission window), where L basically corresponds to the maximum time span (according to QoS) until the data packet should be transmitted. The frequency map can distinguish between unavailable and available radio resources (and may also include information about the predicted energy levels of different radio resources). Other implementations of the radio sensing process are also possible, for example, where the UE does not continuously update such a future resource map, but predicts the radio resources only when needed based on past measurements in the sensing window.

[0236] In summary, it is assumed that the vehicle UE continuously performs a radio resource sensing process to obtain information about future radio resources (whether reservation and / or RSSI prediction, or other information). The vehicle UE should also be able to transmit periodic (and non-periodic) data, and a mode 2 resource allocation process (UE autonomous) should be performed in the connection to select the radio resources to be used for transmitting data within the transmission window (which may also include determining other transmission parameters, such as MCS, etc.). Based on the transmission parameters (such as modulation scheme, coding rate, etc.), the vehicle UE determines the number of resource blocks required for the transmission, and then uses the number of resource blocks thus determined to identify possible radio resources for transmitting data. It is exemplarily assumed that only consecutive resource blocks are used for sidelink transmission.

[0237] The first embodiment provides an improved radio resource allocation process that takes into account the results obtained from a previously performed sensing process. According to the first embodiment, radio resources in a transmission window (i.e., those radio resources from which the UE can select suitable radio resources for transmission) are distinguished between radio resources of a primary subframe and radio resources of a secondary subframe. The secondary subframe of the transmission window should correspond to a subframe in the sensing window in which the vehicle UE does not perform a resource sensing process and therefore obtains less information through sensing. In contrast, when corresponding to a subframe in the sensing window in which the vehicle UE has already performed a sensing process, the subframe of the transmission window is a primary subframe. Therefore, the prediction for the secondary subframe is considered to be less accurate than for the primary subframe, and therefore radio resources from the secondary subframe are less preferably selected during the resource allocation process.

[0238] In more detail, since the vehicle UE does not support simultaneous transmission and reception on the sidelink interface (see the background section), when the vehicle UE performs transmission in a subframe, it cannot simultaneously perform a reception operation and therefore cannot perform a resource sensing process. The resource sensing process collects information about future radio resources for use during the radio resource allocation process. As currently agreed, the sensing process involves at least monitoring radio resource reservations and possibly performing energy measurements. In future 3GPP releases, other types of information may be obtained during the sensing process, and the embodiments presented herein will still apply.

[0239] Assume for example that the vehicle UE performs transmission in subframe t and therefore cannot perform the sensing process in this subframe. Therefore, the vehicle UE may have missed the scheduled transmission (with or without reservation) and / or data transmission of one or more other transmitting devices.

[0240] As currently standardized, periodic vehicle data (such as CAM messages) is transmitted with a periodicity that is a multiple of 100 ms (e.g., 200 ms, 300 ms, 400 ms, ...; the maximum period between two CAM messages is 1 second, and the minimum period is 100 ms). Different or additional periodicities may be defined in the future and should also be covered by the embodiments presented herein. Radio resource reservation is typically performed for periodic data and is therefore based on the possible periodicity of the periodic data described above.

[0241] In subframes where no sensing process is performed, a potentially lost scheduling allocation may only have reserved radio resources within some predetermined time interval, depending on the possible periodicity of the periodic data discussed above. For simplicity, it is assumed that the scheduling allocation typically indicates radio resources for data transmission in the same subframe as the scheduling allocation, so that a lost radio resource reservation at subframe t may reserve radio resources in subframes that are separated by the corresponding data period (e.g., t+100ms, t+200ms, t+300ms, ..., t+1000ms). For the reasons described, a vehicle UE that has performed a transmission in subframe t and therefore has not performed a sensing process in subframe t will consider all relevant subframes t+100ms, t+200ms, t+300ms, ..., t+1000ms (when within the transmission window) as secondary subframes during a possible radio resource allocation process.

[0242] Similarly, the vehicle UE cannot sense the missing data or SA transmission in subframe t through the received signal strength measurement. Considering again that periodic data transmission may only occur at a fixed time interval (e.g., 100ms, or 200ms, or 300ms, or ..., or 1000ms), due to the lack of measurement information for subframe t, the vehicle UE considers that the energy prediction for subframes t+100ms, t+200ms, t+300ms, and ... t+1000ms is not so accurate.

[0243] In this way, the unsensed subframe results in a lack of prediction information for subsequent subframes, and is therefore considered according to the first embodiment as a secondary subframe as opposed to a primary subframe, the sensing process of which has obtained all possible information (e.g., whether radio resources are reserved, and energy measurements of all frequency radio resources of the subframe).

[0244] Then, the vehicle UE should preferably select radio resources from the primary subframe within the transmission window over radio resources from the secondary subframe. In other words, when determining radio resources for transmitting data, the vehicle UE will select radio resources from the secondary subframe only if there are no radio resources from the primary subframe.

[0245] Typically, the selection of radio resources is based on previously determined transmission parameters, such as the modulation scheme and coding rate to be used for the transmitted data. The vehicle UE thereby determines the number of resource blocks required for the transmission. According to current agreements and discussions within 3GPP, it is assumed that consecutive resource blocks are to be used for sidelink transmission. In the following exemplary illustration, it is assumed that three consecutive resource blocks are required to transmit the data. The resulting resource candidates are shown in the following figures, for example, see Figure 10 .

[0246] In conjunction with this process, it is also advantageous to rank the radio resource candidates for the primary subframe separately from the radio resource candidates for the secondary subframe. Accordingly, during the Mode 2 resource allocation process, the vehicle UE, after determining the multiple radio resource candidates in the primary subframe, will then rank them so that the best candidate can be selected for transmitting data. The possible radio resource candidates in the secondary subframe will be ranked separately from the multiple radio resource candidates in the primary subframe, that is, the ranking is performed only on the radio resource candidates in the secondary subframe. During the radio resource allocation process, the vehicle UE will then select the highest ranked candidate from the primary subframe and, if none is available, the highest ranked candidate from the secondary subframe.

[0247] Figure 10 is a frequency-time resource diagram of a data resource pool according to an exemplary implementation of the first embodiment, and exemplarily illustrates the results of the sensing and radio resource allocation process. Figure 10 The frequency-time radio resources that the vehicle UE can generally use to perform data transmission via the sidelink interface are disclosed, for example, suitable radio resources from a data radio resource pool, as described in the background section. Accordingly, a sensing process is also performed (performed in a sensing window) on these radio resources (for example, radio resources of the data transmission resource pool). For ease of explanation, Figure 10 Omitted in Figure 9 The relative energy measurements in the sensing window for the radio resource candidates in the transmission window are shown. Figure 10 As evident in , the UE transmission at subframe t is shown, as well as the resulting secondary subframe m at t+600ms. Figure 10 In the exemplary illustration of , it is assumed that a missed sensing opportunity in subframe t results in only a single secondary subframe m within the transmission window; for example, because the transmission window is only 100 ms. Depending on the length of the transmission window, a UE transmission at subframe t may result in more than one secondary subframe (i.e., t+600 ms, and t+700 ms, t+800 ms, ...). Figure 10Also evident in the figure is the separate ranking process among the radio resource candidates for the primary subframe and among the radio resource candidates for the secondary subframe; the secondary radio resource candidates are framed with dashed lines. Specifically, there are four radio resource candidates from the primary subframe (ranked from 1 to 4), and if no primary radio resource candidate is available, there will be two radio resource candidates from the secondary subframe (ranked from 1 to 2).

[0248] Figure 11 1 shows a simplified and exemplary sequence diagram of the behavior of a vehicle UE according to an exemplary implementation of the first embodiment. Figure 11 As shown, the various steps performed by the vehicle UE are as described above. The resource sensing process is described separately from it to indicate that resource sensing should be performed continuously. The dotted line from the resource sensing process to the radio resource candidate search and ranking steps for the primary and secondary subframes should be understood as the input of information (e.g., radio resource reservation and radio resource energy measurement).

[0249] There are several options on how to perform the radio resource candidate ranking process. Figure 9 A possible, albeit disadvantageous, solution is presented. Alternatively, the candidate ranking may be based solely on the time delay between the radio resource candidate and the packet arrival time; i.e., energy measurements / predictions are not taken into account for the ranking, so that candidates that only cause short delays are preferred over candidates that cause long delays. Other particularly advantageous ranking procedures will be described below as variations of the first embodiment. The ranking procedure may be based on energy measurements performed during the sensing window and the temporal distance of the radio resource candidate from the point in time when data becomes available for transmission. By additionally taking into account the delay that may be caused by transmitting data using the candidate, the waiting time for data transmission should be reduced. At the same time, the resource occupancy potential of the radio resource candidate may also be taken into account by taking into account past RSSI measurements.

[0250] The two characteristics considered for ranking, energy prediction and delay, may be considered in different ways. Specifically, the delay between the radio resource candidate and the packet arrival time may be considered first, and in case there is more than one radio resource candidate with the same time delay, the received signal strength prediction may be used to rank the candidates with the same delay; for example ranking the candidate resources from high to low in ascending order of RSSI such that the candidate with the lowest energy prediction is the highest ranked candidate for the subframe. In contrast, the received signal strength prediction may be considered first, and then in case there is more than one radio resource candidate with the same received signal strength prediction, the time delay may be used for ranking, where shorter time delays have a higher ranking than longer time delays. According to another alternative, a function of delay and received signal strength prediction may be used to rank the radio resource candidates. An exemplary function may be Z i =X*T i +Y*RSSI i X and Y are the weights for time delay characteristics and received signal strength characteristics respectively. i RSSI represents the time distance between radio resource candidate i and the packet arrival time. i represents the prediction of the received signal strength for radio resource candidate i (based on previous measurements during the sensing window). i The smaller , the higher the ranking of resource candidate i. The weights X and Y may be configured by the eNB or predetermined in other ways, for example.

[0251] exist Figure 10 The result of an exemplary ranking process taking into account mainly the time delay as described above is illustrated in FIG. As is apparent therefrom, the highest ranked primary radio resource candidate (ranking value 1) is the radio resource candidate in the primary subframe having the smallest delay relative to the packet arrival time. The remaining radio resource candidates in the primary subframe are also ranked based on their time distance to the packet arrival time. On the other hand, the ranking process for the secondary subframe m must additionally rely on energy measurements performed during the sensing window to distinguish between two radio resource candidates; the exemplary ranking is shown in FIG. Figure 10 Middle picture.

[0252] Another advantageous variant of the first embodiment improves the prediction of the received energy level of the radio resource candidate. Figure 9As described, one possible option is to use the energy measurements in the radio resources corresponding to the radio resources of a specific radio resource candidate in the entire sensing window to predict the received signal strength of the specific radio resource candidate. However, this has the following disadvantage: it may not reflect the actual transmission situation in this subframe of the radio resource candidate. In order to improve the transmission energy prediction, only relevant subframes are considered for prediction. In more detail, the relevant subframes in the sensing window are subframes with a time distance of a possible data period relative to the radio resource candidate to be ranked. As currently assumed for data transmission, the data period is a multiple of 100ms (minimum 100ms, maximum 1000ms). Therefore, in order to improve the energy prediction of a specific subframe m in the transmission window, the relevant subframes in the sensing window are m-100ms, m-200ms, m-300ms, m-400ms... and m-1000ms. Only the energy measurements performed in those relevant subframes in the sensing window are used to predict the energy in subframe m of the transmission window.

[0253] Figure 12 An exemplary illustration is given based on Figure 10 This improved transmission energy prediction of the assumption is adopted and a distinction is made between the six radio resource candidates determined for the primary and secondary subframes. Figure 12 The energy measurements in the corresponding radio resources of subframes u-600ms and u-1000ms are shown for the primary radio resource candidate 1 in subframe u. The energy measurements at the remaining relevant subframes of the sensing window (i.e., u-100ms, u-200ms, ..., u-500ms, u-700ms, u-800ms, u-900ms) are also considered, although not shown for ease of illustration. Figure 12 Similarly, although energy measurements in different radio resources of the relevant subframes are used, the radio resource candidates of the secondary subframe m are associated with subframes m-100s, m-200ms, ..., m-1000ms in the sensing window. Accordingly, Figure 12 The relevant radio resources in subframe m-1000ms are marked for energy prediction. It should be noted that since the vehicle UE performs transmission, energy measurement in the radio resources of subframe m-600ms is not possible. As mentioned above, possible periodic transmissions with a periodicity of 600ms that have an impact on subframe m of the transmission window will not be sensed, which is one of the reasons why subframe m is classified as only secondary for the radio resource allocation process. The received signal strength (i.e., energy) measured in the radio resources of the relevant subframes can then be averaged, for example, to obtain a prediction of the radio resource candidates in the subframes of the transmission window.

[0254] The advantage is that the improved energy prediction is more accurate since it takes into account the possible periodicity of data transmission.

[0255] Other advantageous implementations of the first embodiment provide solutions for these situations where no suitable radio resources can be found in the primary or secondary subframes.As mentioned above, the preemption process allows selecting radio resources from the radio resources in the transmission window even if they have been reserved by other transmitting devices.

[0256] Figure 13 is based on Figure 11 and extended with an exemplary sequence diagram of UE behavior of the preemption process as a step in the case where the vehicle UE cannot find resources in the secondary subframe (also after being unable to find resources in the primary subframe). Figure 13 As is evident in Figure 2, after determining the radio resources during the preemption process, the vehicle UE then determines the corresponding radio resources for the scheduling allocation and then transmits the SA and data. In addition, the preemption block receives as input information from the resource sensing process, such as energy measurements on the radio resources, radio resource reservations made by other devices, and possibly also information about the priority of the radio resource reservations. The latter information requires priority information (such as PPPP, ProSe-Per-Packet-Priority) to be transmitted together with the radio resource reservation and is therefore also decoded and stored by the vehicle UE during the sensing process.

[0257] Figure 14 is a simplified and exemplary sequence diagram of a preemption procedure that may be performed by a vehicle UE when no radio resources are available and should be considered as Figure 13 A possible implementation of the preemption procedure illustrated in . An optional check performed at the beginning of the preemption procedure is whether the data to be transmitted can be discarded (i.e., abandoned so as not to be transmitted). In one example implementation, the vehicle UE determines whether the data should be discarded based on the priority of the data, which can be compared with a suitable priority threshold. The data is typically associated with a ProSe-Per-Packet-Priority (PPPP) indicating the priority of the data. A suitable priority threshold in the vehicle UE can be defined, for example, by the eNodeB, for distinguishing between data that can be discarded and data that cannot be discarded. If the priority is not high enough (e.g., falls below the priority threshold), the data is discarded; otherwise, the preemption procedure then selects radio resources for the data transmission this time, but additionally taking into account reserved radio resources that were initially excluded from the previous candidate search in the primary and secondary subframes. As described above, the discarding of data is an optional check performed by the vehicle UE, and this can therefore be configurable (e.g., by upper layers of the eNB or the vehicle UE).

[0258] Although shown as part of the preemption process, the drop check may also be performed outside of the actual preemption process, such that the preemption process is only performed (without the drop check) when packets are not dropped.

[0259] Furthermore, the decision on whether to discard data may be made by higher layers of the vehicle UE, such as the RRC or application layer.

[0260] Preemption refers to the process of selecting and using radio resources that have been reserved by other transmitting devices to transmit data. As a result, some reserved radio resources are "overwritten" by one's own transmission, which may cause severe interference and should therefore be avoided if possible. However, when the data is important enough, the vehicle UE should determine one or more radio resource candidates with a suitable resource block size (including part or all of the reserved radio resources). If there are more than one resource candidates available, the vehicle UE needs to determine the most suitable candidate. One possible option is to perform a random selection of candidates across the entire transmission window, or preferably in the primary subframe and then in the secondary subframe, as described above.

[0261] According to an advantageous implementation of the first embodiment, the selection of radio resource candidates during the preemption process is improved by taking into account the priority of the radio resource and / or the RSSI prediction determined during the sensing process in the sensing window, so as to alleviate any problems caused by the preemption. In one example, the vehicle UE performs preemption by selecting the radio resource candidate of the reserved radio resource with the lowest priority. Then, if several candidates with the same priority remain, the vehicle UE may select the candidate with the lowest RSSI prediction. In a second example, the vehicle UE selects the radio resource candidate with the lowest RSSI prediction level, and in the case that several candidates remain, the candidate of the radio resource with the lowest priority is selected for transmitting data. Alternatively, a function may be defined based on two parameters (reservation priority and RSSI) that are weighted separately. An exemplary function may be Z i =w1*1 / P i +w2*RSSI i w1 and w2 are weights for the priority characteristic (the lowest priority value is the highest priority) and the received signal strength characteristic, respectively. i represents the priority for a particular radio resource reservation as part of resource candidate i, and RSSI i represents the predicted received signal strength for radio resource candidate i. The vehicle UE should select the one with the smallest (smallest) Z i radio resource candidates with the specified value.

[0262] Optionally, the priority of the reservation can be compared with the priority of the data, so that only reserved radio resources with a lower priority than the data to be transmitted should be preempted. As another option, corresponding priority thresholds and energy thresholds can be defined to limit the radio resource selection to only the "best" radio resources below both thresholds; radio resources above the thresholds are filtered out. As an optional addition, the preemption process can also distinguish between primary and secondary subframes, and candidates in primary subframes should be preferred over candidates in secondary subframes.

[0263] Additionally or alternatively, the preemption process should preferably determine the radio resource candidate that overwrites the least amount of reserved radio resources as a candidate for transmitting data. Specifically, since only a set of contiguous resource blocks can be used for data transmission on the sidelink, preempting only a few reserved resource blocks may be sufficient to obtain a sufficiently large set of resource blocks for data transmission. This reduces interference to other transmitting UEs.

[0264] As another possible criterion for the preemption process, the reserved radio resources may be chosen in such a way as to minimize the number of other devices that will be affected by the preemption, or to maximize the number of other devices so that each device will be less affected by the preemption and still be able to decode the data.

[0265] In case several candidates remain after considering two or three parameters (reservation priority, data priority or RSSI) according to any one of the above examples, the vehicle UE may randomly select one of the remaining radio resource candidates.

[0266] By taking the energy prediction into account for the preemption process, a strong interference of the data transmission performed by the vehicle UE with the preempted data transmission of the vehicle UE located in the immediate vicinity should be avoided.

[0267] After thus determining the appropriate radio resources for transmitting the data, as Figure 13 As shown, the vehicle UE then selects resources for transmitting the scheduling assignment and then transmits the scheduling assignment along with the data.

[0268] According to another advantageous implementation of the first embodiment, the congestion level of the sidelink channel is taken into account for the radio resource allocation process performed at the vehicle UE. The congestion level of the sidelink channel (which may also be referred to as the channel busyness ratio, CBR) is determined by the vehicle UE, for example, by comparing the energy level of sufficient samples over the entire bandwidth or within only one resource pool with a threshold. For example, if 90% of the samples have an energy level above the threshold, the CBR is 90%. The threshold may be fixed or configured or pre-configured by the eNB. The CBR measures the busyness level of the carrier or resource pool. The vehicle UE may use the CBR to determine whether to discard data based on the channel state. Typically, this CBR check is optional and may be configured, for example, by the eNodeB or pre-configured (for example, by the operator), thereby configuring the UE as to whether and how to perform the CBR check. For example, if the eNodeB is conservative and wants to protect the sidelink carrier, it may therefore configure some or all UEs in its cell (for example, via system information broadcast) to perform such a CBR check. On the other hand, if the eNodeB is interested in achieving higher throughput, the UE may be configured not to perform this CBR check. One possible implementation of the CBR check would be to take the priority of the data being transmitted and compare it to a priority threshold, which could optionally depend on the CBR detected for the sidelink channel. For example, only if the priority of the data being transmitted is sufficiently high will the process proceed despite the high congestion level of the channel. On the other hand, low-priority data could be discarded due to a busy channel.

[0269] In addition to or as an alternative to the data priority, the traffic type of the data being transmitted can also be considered in the CBR drop function. For example, different thresholds can be defined for secure and non-secure traffic. Assume that priority levels range from 1 to 5, with higher numbers indicating lower priority. For a CBR of 90%, secure traffic with priority level 5 and non-secure traffic with priority levels 5, 4, and 3 should be dropped. On the other hand, if the CBR is 80%, secure traffic will never be dropped, and only non-secure traffic with priority level 5 should be dropped. If the CBR is 70%, secure traffic will never be dropped, but non-secure traffic with priority levels 5 or 4 should be dropped, and so on.

[0270] If data is discarded, the responsible higher layer is informed of the failure to transmit the data, for example, so that the higher layer can decide to transmit the data again or also discard the data at the higher layer and inform the user of the transmission failure.

[0271] Figure 15 is based on Figure 11and extended with an exemplary sequence diagram of the CBR check as described above. Specifically, after data becomes available for transmission, the vehicle UE can decide whether to discard the data by considering the channel busy ratio. If the vehicle UE decides not to discard the data, it continues from Figure 11 The process is known in the art and described in detail above.

[0272] The CBR check may be considered as a part of the resource allocation process or a step before resource allocation in order to determine whether resource allocation should be started.

[0273] Furthermore, a radio resource sensing procedure can be performed for each radio resource pool configured for Mode 2 resource allocation in the vehicle UE. In this case, whether and how the vehicle UE uses CBR checking can be configured for each resource pool. For example, during configuration of the data resource pool, the eNodeB can indicate whether and how CBR checking is performed. For out-of-coverage UEs and corresponding radio resource pools, the CBR configuration can be part of the pre-configuration for each resource pool.

[0274] According to another advantageous implementation of the first embodiment, a collision check is provided in order to determine whether a scheduling assignment and a planned transmission of data, respectively, collides with a data transmission of another UE. Figure 16 is based on Figure 11 and is extended with an exemplary sequence diagram of an implementation of collision checking as described below. Figure 16 As is evident in , after selecting suitable resources for transmitting the scheduling assignment and the data, the vehicle UE proceeds with a sensing procedure, thereby monitoring scheduling assignments transmitted by other UEs that may have resource reservations for the future. Based on the scheduling assignments received from other UEs, the vehicle UE can therefore check whether the planned transmission of the scheduling assignment collides with a transmission announced by another UE as indicated by the monitored scheduling assignments. In the event of a collision, the vehicle UE can decide how to proceed further and can, for example, compare the priorities of the two colliding transmissions; namely its own SA transmission and the transmission of the other UE. In the event that the own SA transmission has a higher priority, the vehicle UE continues with the transmission of the scheduling assignment as planned. In the other case, the vehicle UE can return to the first step of the radio resource allocation procedure in order to determine new radio resources for the scheduling assignment and, if necessary, also for the data transmission. Alternatively, the SA and the data are discarded in the event of a collision; in particular when the priority of the own SA transmission is lower.

[0275] Collision detection acts in a similar way on data transmission. It is assumed that a scheduling assignment for data transmission has been transmitted. The vehicle UE continuously performs the sensing process until the time of data transmission and can thus detect possible data transmissions by other devices that collide with its own data transmission. In the event of such a collision, the vehicle UE can, for example, compare the priorities of the two data transmissions. In the event that its own data transmission has a higher priority, the vehicle UE continues to transmit the data as previously planned. In another case, the vehicle UE may have to return to the first step of the radio resource allocation process in order to determine new radio resources for data and SA transmission. Alternatively, the data is discarded in the event of a collision; in particular when the priority of its own data transmission is lower.

[0276] In the above, different implementations of the first embodiment have been described, wherein Figure 11 The "basic" implementation is described in Figure 13 、 14 , 15 and 16. Although each extension is described and illustrated separately, some or all of them can be combined to form a complete UE behavior, which then includes Figure 13 The preemption process, and / or Figure 15 CBR discard functionality, and / or Figure 16 Collision check.

[0277] In the above, it is assumed that the vehicle UE always uses the result of the sensing process for UE autonomous resource allocation (mode 2). However, whether and how sensing is used for resource allocation may alternatively be configurable and / or depend on a radio resource pool from which the vehicle UE selects radio resources for transmission. In more detail, in one implementation, the eNodeB responsible for the vehicle UE controls whether and how the sensing process affects the radio resource allocation. For example, the eNodeB may broadcast a corresponding configuration in its cell so that all vehicle UEs in the cell receiving the configuration are informed whether and how sensing is used for UE autonomous resource allocation. Alternatively, a dedicated message is transmitted from the radio base station to only one or more vehicle UEs in order to control whether and how the sensing process is implemented in those vehicle UEs.

[0278] Second embodiment

[0279] Below, a second embodiment will be described that can be used in combination with various implementations of the first embodiment. In conjunction with the first embodiment, it is simply assumed that the vehicle UE selects resources for transmission scheduling allocations, without detailing how the vehicle UE actually performs resource selection. As described in the background section, the selection of resources for transmission scheduling allocations was clearly defined in previous releases of 3GPP. In short, for UE-autonomous radio resource allocation (Mode 2), the vehicle UE can randomly select radio resources from the corresponding scheduling allocation resource pool, and can also select the T-RPT mode for repeating the scheduling allocation. However, while 3GPP has discussed and agreed to implement improvements to resource selection for data transmission (as described above, the introduction of a radio resource reservation mechanism and a sensing process), there has been no discussion or agreement on how to improve the transmission of scheduling allocations for future releases. One motivation for the agreement on improvements to V2X data transmission is to increase the reliability of such transmissions, which may not be guaranteed by purely random selection of radio resources for data transmission (e.g., in terms of the rate of collisions). For example, the number of vehicle UEs may increase in the future, and the random resource selection mechanism for transmission scheduling allocations may lead to an increase in the number of failures due to collisions. However, robust transmission of scheduling assignments, especially in vehicular communication environments, is as important as robust transmission of data.

[0280] Therefore, the second embodiment provides an improved UE-autonomous radio resource allocation process for selecting radio resources for scheduled allocation transmission. The transmission of scheduled allocation is improved so as to mimic the improvements foreseen for the data transmission discussed in the first embodiment. Accordingly, the implementation of the second embodiment provides a resource sensing process performed by the vehicle UE for the radio resources of one or more SA resource pools that can be used by the transmitting device to transmit scheduled allocations. It should be noted that the radio resource sensing process described in the first embodiment may sense different radio resources, namely the radio resources of the data resource pool that can be used by the transmitting device to transmit data. However, the radio resources of the scheduled allocation resource pool and the radio resources of the data resource pool may overlap. In any case, in a similar manner to that described in detail in the first embodiment, the vehicle UE should obtain information about future scheduled allocation radio resources by continuously performing the sensing process in those radio resources.

[0281] As will be described in more detail in the following implementation of the second embodiment, not only is radio resource reservation implemented for data transmission as described in the first embodiment, but radio resource reservation should also be implemented for the transmission of scheduled assignments. The radio resource reservation for scheduled assignments and data can be similar. In short, by providing appropriate indications in the scheduled assignment, the radio resources used to transmit the current scheduled assignment can be reserved for the transmission of one or more future scheduled assignments.

[0282] By monitoring the scheduled allocations transmitted by other devices, the resource sensing process should therefore also allow the vehicle UE to obtain information about whether radio resources are reserved by other transmitting devices and which radio resources are reserved by other transmitting devices for the transmission of the scheduled allocation. These reserved radio resources can then be excluded from the radio resource allocation process performed by the vehicle UE to select the radio resources for the transmission scheduled allocation. The radio sensing process can also include energy measurements (e.g., received signal strength, RSSI) in the entire frequency resources allocated for the transmission scheduled allocation. In the future, other types of information can also be collected. Therefore, the sensing process collects information about future radio resources to be used for the transmission scheduled allocation, which information can be used during the resource allocation process to select the best radio resources for the transmission scheduled allocation.

[0283] It is assumed that a vehicular UE shall transmit periodic data and perform a UE autonomous radio resource allocation procedure in order to determine resources for transmitting the scheduled assignment and pending data.

[0284] As already discussed in detail in conjunction with the first embodiment, the radio resource allocation process can be improved by distinguishing between the radio resources of the primary subframe and the radio resources of the secondary subframe, taking into account the results obtained from the sensing process. With respect to the primary subframe, which corresponds to a subframe in the sensing window in which the vehicle UE always performs the sensing process and thus obtains all possible information, the secondary subframe of the transmission window should correspond to a subframe in the sensing window in which the vehicle UE does not always perform the resource sensing process and thus obtains less information through sensing. Consequently, the vehicle UE may have missed a reservation for a scheduled assigned transmission made by another UE in the secondary subframe, or missed an energy measurement that affects the energy prediction for the secondary subframe, as described in detail in the first embodiment.

[0285] Therefore, the prediction for the secondary subframe is not as accurate as the prediction for the primary subframe, and thus the radio resources from the secondary subframe are less preferentially selected relative to the radio resources from the primary subframe.

[0286] As a result, this improvement of the resource allocation procedure related to the selection of radio resources for data transmission described in detail for the first embodiment can be applied to the selection of radio resources for scheduling allocation transmission according to the second embodiment.

[0287] Figure 17 is similar to the first embodiment Figure 11, illustrating an exemplary and simplified UE behavior according to the implementation of the second embodiment. As is apparent therefrom, the selection of radio resources for transmission scheduling allocations is divided into a search in the primary subframe and a subsequent search in the secondary subframe. Specifically, after data becomes available for transmission, the vehicle UE should select radio resources for SA transmission preferably from the primary subframe within the transmission window, and in the event that there are no radio resources available for SA transmission in the primary subframe, the vehicle UE should search for radio resources for SA transmission within the secondary subframe. The process then continues with the transmission of the scheduled allocation and the subsequent transmission of pending data.

[0288] Figure 18 The diagram illustrates frequency time radio resources for a scheduling allocation resource pool that can be used by vehicle UEs to transmit scheduling allocations. Figure 10 In a similar way, Figure 18 The diagram illustrates how the primary and secondary subframes are defined within a transmission window as a result of not performing the sensing process in one of the subframes of the sensing window. Similarly, for the transmission of a scheduled assignment, the vehicle UE must first determine the appropriate transmission parameters and, therefore, the number of resource blocks that will be required for the SA transmission. As currently agreed, the scheduled assignment should be transmitted using two physical resource block pairs. The vehicle UE then determines the possible radio resource candidates that will be available for the transmission of the scheduled assignment, where Figure 18 An exemplary result of a candidate search is illustrated in .

[0289] The radio resource candidates of the primary subframe should be ranked separately from the radio resource candidates from the secondary subframe, for example, in the same or similar manner as discussed in the first embodiment. Figure 18 In the figure, Figure 18 Four primary SA radio resource candidates are shown, and two secondary SA radio resource candidates are shown separately. In particular, the various different implementations of the ranking process for data transmission discussed in accordance with the first embodiment can also be reused to rank the radio resource candidates available for transmission scheduling allocation. For example, although it is disadvantageous, in combination with Figure 9 The ranking discussed is possible. Alternatively, the candidate ranking may be based solely on the time delay between the radio resource candidate and the packet arrival time, particularly taking into account the need to transmit the scheduling allocation before (or in the same subframe as) the data transmission. Another option for candidate ranking is to consider the time delay and energy prediction of the radio resource candidate based on energy measurements performed during the sensing process; various different implementations were presented above in conjunction with the first embodiment and can be reused here to implement the second embodiment.

[0290] A particularly advantageous implementation of the first embodiment improves energy prediction, such as in combination with Figure 12These improved energy measurements and predictions can also be applied to the resource sensing process performed by the vehicular UE on the radio resources available for transmission scheduling allocation. Accordingly, the energy prediction of a particular resource candidate in subframe m should consider measuring only the subframes related to that subframe of the resource candidate (i.e., separated by a possible period) in the sensing window, m-100ms, m-200ms, m-300ms, ..., m-1000ms.

[0291] like Figure 17 As shown, a preemption process can be foreseen during the resource allocation process for situations where suitable radio resources cannot be found within the primary and secondary subframes. In a manner similar to that discussed in detail in the first embodiment, radio resources reserved by other UEs for transmitting a scheduled assignment can be preempted by the vehicle UE to still be able to transmit the scheduled assignment. Furthermore, the preemption process can include a determination as to whether the scheduled assignment should be discarded, where this determination can be based on the priority of the data for which the scheduled assignment is to be transmitted, which can be compared to an appropriate priority threshold. If the data, and therefore the scheduled assignment, has sufficient priority, the vehicle UE can then determine resource candidates for transmitting the scheduled assignment, this time also considering the reserved radio resources. Various advantageous implementations of the preemption process were discussed in detail in conjunction with the first embodiment, and may also be considered for reusing to improve the selection of radio resource candidates for transmitting the scheduled assignment. For example, the priority of the reserved radio resources and / or RSSI predictions determined during the sensing process within the sensing window can be considered. Furthermore, the priority of the reserved radio resources can be compared with the priority of the data to be transmitted. Furthermore, the preemption process can differentiate between primary and secondary subframes and preferentially select radio resource candidates from the primary subframe.

[0292] In summary, the vehicle UE thus selects the best radio resources for transmitting the scheduled assignment.As mentioned above, the vehicle UE should also reserve radio resources for the next transmission of the scheduled assignment.

[0293] In some implementations of the second embodiment, whether the vehicle UE should apply semi-persistent scheduling (e.g., radio resource reservation and sensing process) to the transmission of the scheduled allocation can be configurable. According to an exemplary implementation, the eNodeB controlling the vehicle UE can decide whether some or all UEs in its cell should improve the scheduled allocation transmission by additionally reserving radio resources for future transmission of the scheduled allocation, and performing radio resource selection based on the results of the sensing process in the radio resources of the corresponding SA resource pool. The eNodeB can then inform the vehicle UE accordingly. For example, in the case where all UEs in the cell of the eNodeB should be configured in the same way, the eNodeB can broadcast a system information message in its cell so that all UEs receiving the broadcast message configure the SA transmission process as indicated.

[0294] On the other hand, how the scheduling assignment is transmitted can be coupled to the transmission process followed by the vehicle UE when transmitting data. Therefore, if the vehicle UE applies semi-persistent scheduling to data transmission, it should also apply semi-persistent scheduling to the corresponding SA transmission; and the same applies to the sensing process. When the UE does not use semi-persistent scheduling, the transmission of the scheduling assignment can be handled in the same manner as described in the prior art, for example, by randomly selecting radio resources from a suitable SA radio resource pool without reference to the results of the sensing process.

[0295] As an alternative or in addition to transmitting broadcast messages in its cell, the eNodeB may transmit dedicated messages to selected vehicular UEs, and these UEs will thus configure themselves according to the instructions in the dedicated message. Thus, the eNodeB may selectively configure vehicular UEs to perform semi-persistent scheduling for transmission scheduling assignments.

[0296] Whether and how to perform the configuration of the scheduled allocation transmission may also depend on the specific SA resource pool, so that the semi-persistent scheduling and sensing procedures are performed when the radio resources for the scheduled allocation transmission are selected from the specifically configured radio resource pool. A corresponding indication at the beginning when configuring the radio resource pool may be sufficient, for example, 1 bit for data and 1 bit for SA transmission.

[0297] As described below, the second embodiment provides several implementations for how a device receiving a scheduling assignment can infer whether the received scheduling assignment also reserves radio resources for the transmission of one or more future scheduled assignments. One option is to provide a corresponding field (e.g., 1 bit) in the scheduling assignment, where the 1-bit value indicates that the scheduling assignment also reserves radio resources for the transmission of one or more future scheduled assignments (e.g., those used to transmit the current scheduling assignment). In contrast, the receiving entity interprets another bit value of the scheduling assignment field as indicating that no radio resource reservation is to be made for the transmission of the scheduling assignment. Alternatively, instead of providing a separate field for reserving radio resources for a scheduling assignment, other implementations of the second embodiment rely on implicit indications, such as using a corresponding field in the scheduling assignment to indicate whether radio resource reservation is to be performed for data transmission. Thus, the scheduling assignment indicates that whenever data resources are reserved, the corresponding scheduling assignment resources should also be reserved. For example, the scheduling assignment may include a "periodicity" field, which may indicate the periodicity of the radio resource reservation, the number of reservation instances, etc. For example, the inclusion of a value of 0 in the periodicity field indicates that no radio reservation (for both data transmission and SA transmission) is to be made.

[0298] In the above implementation of the second embodiment, retransmissions to be performed on the scheduled assignment have not been considered. However, in order to increase the robustness of the scheduled assignment transmission, one or more retransmissions of the scheduled assignment should be performed by the vehicle UE on the sidelink interface. In the connection, in an exemplary implementation, a fixed number of (re)transmissions can be preconfigured. As in the prior art, the vehicle UE can transmit the retransmissions of the scheduled assignment with a fixed time relationship relative to the first transmission of the scheduled assignment. Alternatively, another association between the first transmission and the retransmission of the scheduled assignment can be agreed between the vehicle UE and the possible receiving entity. According to a further alternative solution, the vehicle UE can also randomly select radio resources for the retransmission of the scheduled assignment, as is done for the first transmission. For example, the radio resources available for the scheduled assignment transmission can be further divided into resources for the first transmission and resources for further retransmissions of the scheduled assignment.

[0299] However, randomly selecting radio resources for retransmissions of an assignment can also be problematic. Specifically, a scheduling assignment is transmitted using a specific radio resource within a set of radio resources, and a potential receiving entity detects the scheduling assignment by blind decoding within the set of radio resources (also known as a radio resource search space). In prior art procedures, retransmissions of a scheduling assignment are performed with a fixed time relationship relative to the first transmission of the scheduling assignment, so that the receiving entity knows which (re)transmissions of a specific scheduling assignment belong together (e.g., for properly performing soft combining to successfully decode the scheduling assignment). However, by also implementing random resource selection for retransmissions of a scheduling assignment, this fixed time relationship can no longer be guaranteed.

[0300] Therefore, it is necessary to provide a new mechanism that allows a receiving entity to associate all transmissions and retransmissions of a specific scheduling assignment. According to an exemplary implementation of the second embodiment, a common identifier can be included in the scheduling assignment transmissions in order to associate them together. Accordingly, a receiving device receiving individual transmissions for a specific scheduling assignment can then associate the correct transmission of the scheduling assignment based on the common identifier. According to an example, the common identifier can be a source identifier that identifies the vehicle UE as the source of the transmission and / or the current application that generated the data for which the scheduling assignment is transmitted. The common identifier can be part of the scheduling assignment or can be encoded as a layer 1 identifier or part of a CRC check.

[0301] A further implementation of the second embodiment improves the selection of radio resources for retransmissions of a scheduled assignment by basing the selection of resources on the results of a sensing process (e.g., in the same way as for the first transmission of a scheduled assignment discussed above). As already discussed for the above-described random selection of radio resources for SA transmissions, when the selection of radio resources is improved based on sensing results, a fixed time relationship between the first transmission and the retransmission can no longer be guaranteed. Therefore, it is necessary to provide a new mechanism that allows a receiving entity to associate all transmissions and retransmissions of one particular scheduled assignment. According to an exemplary implementation of the second embodiment, a common identifier as described above may be included in the scheduled assignment transmission in order to associate them together. According to an example, the common identifier may be a source identifier that identifies the vehicle UE as the source of the transmission and / or the current application that generated the data for which the scheduled assignment is transmitted. The common identifier may be part of the scheduled assignment or may be encoded as part of a layer 1 identifier.

[0302] Hardware and software implementations of the present disclosure

[0303] Other exemplary embodiments relate to implementing the above-described various embodiments using hardware, software, or software combined with hardware. In this regard, a user terminal (mobile terminal) is provided. The user terminal is suitable for performing the method described herein and includes corresponding entities (e.g., receiving unit, sending unit, processing unit) for appropriately participating in the method.

[0304] It should be further understood that various embodiments can be implemented or executed using a computing device (processor). The computing device or processor can be, for example, a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, etc. The combination of these devices can also execute or implement various embodiments. Specifically, each functional block used in the description of each embodiment described above can be implemented by an LSI as an integrated circuit. They can be formed as a chip individually, or a chip can be formed to include some or all functional blocks. They can include data input and output coupled thereto. Depending on the difference in the degree of integration, the LSI herein can be referred to as IC, system LSI, super LSI or ultra LSI. However, the technology for implementing integrated circuits is not limited to LSI, and can be implemented by using a dedicated circuit or a general-purpose processor. In addition, an FPGA (field programmable gate array) that can be programmed after manufacturing the LSI or a reconfigurable processor that can reconfigure the connection and setting of the circuit units deployed inside the LSI can be used.

[0305] Furthermore, various embodiments may be implemented via software modules executed by a processor or directly in hardware. Furthermore, combinations of software modules and hardware implementations may be possible. Software modules may be stored on any type of computer-readable storage medium (e.g., RAM, EPROM, EEPROM, flash memory, registers, hard disk, CD-ROM, DVD, etc.). It should also be noted that individual features of different embodiments may be combined individually or arbitrarily to form another embodiment.

[0306] It will be appreciated by those skilled in the art that many variations and / or modifications may be made to the disclosure shown in the specific embodiments. Therefore, the present embodiments are therefore considered in all respects to be illustrative and not restrictive.

[0307] A non-limiting embodiment of the present disclosure provides a transmitting device for determining radio resources to be used for data transmission from the transmitting device to one or more receiving devices via a sidelink interface, wherein the transmitting device includes: a receiving unit and a processing unit, which performs a resource sensing process to obtain information about radio resources that the transmitting device can use to transmit data at a later point in time, after the data becomes available for transmission, the processing unit performs autonomous radio resource allocation to select radio resources to be used for transmitting data within a transmission window before the data becomes available for transmission based on the information obtained through the resource sensing process during the sensing window, and wherein the autonomous radio resource allocation includes preferentially selecting radio resources in primary subframes of the transmission window relative to radio resources in secondary subframes of the transmission window, and wherein the secondary subframes in the transmission window correspond to those subframes in the sensing window for which the transmitting device did not perform the resource sensing process, and the primary subframes in the transmission window correspond to those subframes in the sensing window for which the transmitting device performed the resource sensing process.

[0308] According to the transmitting device in an embodiment of the present disclosure, the resource sensing process includes: in order to determine the radio resources reserved by other transmitting devices, the receiving unit and the processing unit monitor the scheduling information transmitted by the other transmitting devices, the scheduling information indicates the radio resources reserved by the other transmitting devices for a later time point, and measures the received signal energy in the radio resources to identify the radio resources used for transmission by the other transmitting devices.

[0309] According to a transmitting device in an embodiment of the present disclosure, the processing unit determines secondary subframes as those subframes of the transmission window, in which the resource sensing process does not obtain all possible information during the sensing window, optionally, the loss information for the secondary subframes includes: possible reservation of radio resources by other transmitting devices during the subframes in the sensing window in which the transmitting device does not perform the resource sensing process, optionally, the determination of the secondary subframes is based on possible periods of radio resource reservation that can be performed by other transmitting devices, and / or information about the received signal energy in the radio resources of the subframes in the sensing window in which the transmitting device does not perform the resource sensing process.

[0310] According to the transmitting device in an embodiment of the present disclosure, the autonomous radio resource allocation further includes: determining one or more primary transmission radio resource candidates within a primary subframe, and optionally determining one or more secondary transmission radio resource candidates within a secondary subframe, and in a case where there is more than one primary transmission radio resource candidate, the processing unit performs candidate ranking of the primary transmission radio resource candidates, and in a case where there is more than one secondary transmission radio resource candidate, the processing unit performs candidate ranking of the secondary transmission radio resource candidates, wherein the candidate ranking of the one or more primary transmission radio resource candidates is separate from the ranking of the one or more secondary transmission radio resource candidates, and optionally, wherein the candidate ranking takes into account the temporal distance of the radio resource candidates from the time point when data becomes available for transmission, and the candidate ranking by A received signal energy prediction for the radio resource to be ranked obtained by the resource sensing process, optionally wherein the received signal energy prediction for the radio resource to be ranked is based on measurements of the received signal energy of the corresponding radio resource in all subframes of the sensing window, or based on measurements of the received signal energy of the corresponding radio resource in subframes of the sensing window that are related to the subframes of the radio resource to be ranked, optionally wherein the related subframes are those subframes of the sensing window that have a distance from the radio resource to be ranked that is a multiple of a possible transmission period by other transmitting devices, optionally wherein the candidate ranking first considers time distance and then the received signal energy, or wherein the candidate ranking first considers received signal energy and then time distance, or wherein the candidate ranking is based on a function of time distance and received signal energy.

[0311] According to the transmitting device in the embodiment of the present disclosure, when data transmission or scheduling allocation transmission for data transmission is performed in a subframe, the transmitting device does not perform a resource sensing process in the subframe.

[0312] According to a transmitting device in an embodiment of the present disclosure, wherein, in a case where no radio resources can be selected for the transmission of data, the processing unit determines to discard the data if the priority of the data available for transmission is lower than the preemption priority threshold, and in a case where the data is not discarded, the processing unit performs a resource preemption process to select radio resources to be used for the transmission of data from the radio resources reserved by one or more other transmitting devices in other transmitting devices, optionally, wherein, when performing the resource preemption process, the processing unit selects the radio resources to be used for the transmission of data based on the following: the priority of the reserved radio resources, and / or the priority of the data to be transmitted, and / or the received signal energy measured by the resource sensing process in the radio resources of the corresponding subframe in the sensing window, optionally, wherein the selection of the radio resources in the resource preemption process first considers the priority of the reserved radio resources and then the received signal energy of the reserved radio resources, or first considers the received signal energy of the reserved radio resources and then the priority of the reserved radio resources, or is based on a function of the priority of the reserved radio resources and the received signal energy.

[0313] According to a transmitting device in an embodiment of the present disclosure, wherein a receiving unit and a processing unit determine a channel busy ratio of a sidelink interface, the channel busy ratio indicating a congestion level of the sidelink interface, and wherein the processing unit performs a data discarding process to determine whether data that becomes available for transmission should be discarded before performing autonomous radio resource allocation based on the determined channel busy ratio of the sidelink interface, and wherein in the case where the processing unit determines not to discard the data, the processing unit performs autonomous radio resource allocation, optionally wherein during the data discarding process, the processing unit discards the data when it determines that the priority of the data that becomes available for transmission is lower than a channel priority threshold, the channel priority threshold depending on the determined channel busy ratio of the sidelink interface, optionally wherein the transmitting device is configured by a radio base station, the radio base station controls whether the transmitting device performs the data discarding process or not, optionally wherein the configuration of the data discarding process is separate for each of a plurality of resource pools, the plurality of resource pools being capable of being used by the transmitting device to select radio resources for transmitting data, optionally wherein the channel priority threshold also depends on the type of data that becomes available for transmission, optionally wherein the channel priority threshold associated with safety data is lower than the channel priority threshold associated with non-safety data.

[0314] According to the transmitting device in an embodiment of the present disclosure, the autonomous radio resource allocation includes: excluding radio resources reserved by other transmitting devices from multiple transmission radio resources, and / or the radio resource candidates within the subframe include one or more resource blocks continuous in the frequency domain.

[0315] According to a transmitting device in an embodiment of the present disclosure, the sensing window considered for autonomous radio resource allocation includes frequency-time radio resources starting at a predetermined time point before data becomes available for transmission and ending at the time point when the data becomes available for transmission, and the transmission window includes frequency-time radio resources starting at a starting subframe immediately after the subframe at which the data becomes available for transmission and ending at a subframe at a predetermined distance from the starting subframe, wherein the distance depends on the delay requirement for the data becoming available for transmission to be met by the transmitting device.

[0316] A non-limiting embodiment of the present disclosure provides a method for a transmitting device, the transmitting device being used to determine radio resources to be used for data transmission from the transmitting device to one or more receiving devices via a sidelink interface, wherein the method includes the following steps performed by the transmitting device: performing a resource sensing process to obtain information about radio resources that the transmitting device can use to transmit data at a later point in time, and after the data becomes available for transmission, performing autonomous radio resource allocation to select radio resources to be used for transmitting data within a transmission window before the data becomes available for transmission based on the information obtained through the resource sensing process during the sensing window, wherein the autonomous radio resource allocation includes preferentially selecting radio resources in primary subframes of the transmission window relative to radio resources in secondary subframes of the transmission window, and wherein the secondary subframes in the transmission window correspond to those subframes in the sensing window for which the transmitting device did not perform the resource sensing process, and the primary subframes in the transmission window correspond to those subframes in the sensing window for which the transmitting device performed the resource sensing process.

[0317] According to the method in an embodiment of the present disclosure, the resource sensing process includes: · In order to determine the radio resources reserved by other transmitting devices, monitoring the scheduling information transmitted by other transmitting devices, the scheduling information indicating the radio resources reserved by other transmitting devices for a later time point, · Measuring the received signal energy in the radio resources so as to identify the radio resources used for transmission by other transmitting devices.

[0318] According to the method in an embodiment of the present disclosure, the method also includes: determining secondary subframes as those subframes of the transmission window, in which the resource sensing process does not obtain all possible information during the sensing window, optionally, wherein the loss information of the secondary subframes includes: possible reservation of radio resources by other transmitting devices during the subframes in the sensing window in which the transmitting device does not perform the resource sensing process, optionally, wherein the determination of the secondary subframes is based on the possible period of radio resource reservation that can be performed by other transmitting devices, and / or information about the received signal energy in the radio resources of the subframes in the sensing window in which the transmitting device does not perform the resource sensing process.

[0319] According to a method in an embodiment of the present disclosure, wherein the autonomous radio resource allocation further comprises: determining one or more primary transmission radio resource candidates within a primary subframe, and optionally determining one or more secondary transmission radio resource candidates within a secondary subframe, in a case where there is more than one primary transmission radio resource candidate, the method comprises performing candidate ranking of the primary transmission radio resource candidates, and in a case where there is more than one secondary transmission radio resource candidate, the method comprises performing candidate ranking of the secondary transmission radio resource candidates, wherein the candidate ranking of the one or more primary transmission radio resource candidates is separate from the ranking of the one or more secondary transmission radio resource candidates, optionally wherein the candidate ranking takes into account a temporal distance of the radio resource candidates from a point in time when data becomes available for transmission, and a distance across the resource candidate. A received signal energy prediction for the radio resource to be ranked obtained by the sensing process, optionally wherein the received signal energy prediction for the radio resource to be ranked is based on measurements of the received signal energy of the corresponding radio resource in all subframes of the sensing window, or based on measurements of the received signal energy of the corresponding radio resource in subframes of the sensing window that are related to the subframes of the radio resource to be ranked, optionally wherein the related subframes are those subframes of the sensing window that have a distance from the radio resource to be ranked that is a multiple of a possible transmission period by other transmitting devices, optionally wherein the candidate ranking first considers time distance and then the received signal energy, or wherein the candidate ranking first considers received signal energy and then time distance, or wherein the candidate ranking is based on a function of time distance and received signal energy.

[0320] According to a method in an embodiment of the present disclosure, wherein, in a case where no radio resources can be selected for transmission of data, the method includes determining to discard the data if the priority of the data available for transmission is lower than a preemption priority threshold, and in a case where the data is not discarded, the method includes performing a resource preemption process to select radio resources to be used for transmission of data from among the radio resources reserved by one or more other transmitting devices in other transmitting devices, optionally, wherein, when performing the resource preemption process, the method includes: selecting the radio resources to be used for transmission of data based on: the priority of the reserved radio resources, and / or the priority of the data to be transmitted, and / or the received signal energy measured by the resource sensing process in the radio resources of the corresponding subframe in the sensing window, optionally, wherein the selection of radio resources in the resource preemption process first considers the priority of the reserved radio resources and then the received signal energy of the reserved radio resources, or first considers the received signal energy of the reserved radio resources and then the priority of the reserved radio resources, or is based on a function of the priority of the reserved radio resources and the received signal energy.

[0321] According to a method in an embodiment of the present disclosure, the method includes: determining a channel busy ratio of a sidelink interface, the channel busy ratio indicating a congestion level of the sidelink interface, and before performing autonomous radio resource allocation based on the determined channel busy ratio of the sidelink interface, performing a data discarding process to determine whether data that becomes available for transmission should be discarded, and wherein in the case where the method determines not to discard the data, a step of performing autonomous radio resource allocation is performed, optionally wherein during the data discarding process, the method includes discarding the data when it is determined that the priority of the data that becomes available for transmission is lower than a channel priority threshold, the channel priority threshold depends on the determined channel busy ratio of the sidelink interface, optionally wherein the transmitting device is configured by a radio base station, the radio base station controls the transmitting device to perform or not perform the data discarding process, optionally wherein the configuration of the data discarding process is separate for each of a plurality of resource pools, and the plurality of resource pools can be used by the transmitting device to select radio resources for transmitting data, optionally wherein the channel priority threshold also depends on the type of data that becomes available for transmission, optionally wherein the channel priority threshold related to safety data is lower than the channel priority threshold related to non-safety data.

[0322] A non-limiting embodiment of the present disclosure provides a transmitting device for transmitting scheduling allocations and data to one or more receiving devices via a sidelink interface, wherein the transmitting device includes: a receiving unit and a processing unit, performing a resource sensing process to obtain information about radio resources that the transmitting device can use to transmit the scheduling allocation at a later point in time, after first data becomes available for transmission, the processing unit performing an autonomous radio resource allocation process to select radio resources within a transmission window for transmitting the first data based on the information obtained by the resource sensing process during the sensing window before the first data becomes available for transmission, and select radio resources within the transmission window for transmitting the first scheduling allocation, wherein the first scheduling allocation includes information about the selected radio resources for transmitting the first data in the transmission window, the transmitting unit transmits the first scheduling allocation using the selected radio resources, and transmits the first data using the selected radio resources, and wherein the first scheduling allocation also indicates reserved radio resources, which can be used by the transmitting device at a later point in time to transmit a second scheduling allocation for second data.

[0323] According to a transmitting device in an embodiment of the present disclosure, the autonomous radio resource allocation performed to select radio resources within a transmission window to be used for transmitting a first scheduling allocation includes: preferably selecting radio resources in a primary subframe of the transmission window relative to radio resources in a secondary subframe of the transmission window, and wherein the secondary subframes in the transmission window correspond to those subframes in the sensing window in which the transmitting device does not perform a resource sensing process, and the primary subframes in the transmission window correspond to those subframes in the sensing window in which the transmitting device performs a resource sensing process, optionally wherein the processing unit determines the secondary subframes as those subframes of the transmission window in which the resource sensing process does not obtain all possible information during the sensing window, optionally wherein the loss information for the secondary subframes includes: possible reservations of radio resources by other transmitting devices during subframes in the sensing window in which the transmitting device does not perform a resource sensing process, optionally wherein the determination of the secondary subframes is based on possible periods of radio resource reservations that can be made by other transmitting devices, and / or information about received signal energy in radio resources of subframes in the sensing window in which the transmitting device does not perform a resource sensing process.

[0324] According to the transmitting device in an embodiment of the present disclosure, the autonomous radio resource allocation performed to select radio resources within a transmission window to be used for transmitting the first scheduling allocation also includes: determining one or more primary transmission radio resource candidates within a primary subframe, and optionally determining one or more secondary transmission radio resource candidates within a secondary subframe, and in the case where there is more than one primary transmission radio resource candidate, the processing unit performs candidate ranking of the primary transmission radio resource candidates, and in the case where there is more than one secondary transmission radio resource candidate, the processing unit performs candidate ranking of the secondary transmission radio resource candidates, wherein the candidate ranking of one or more primary transmission radio resource candidates is separate from the ranking of one or more secondary transmission radio resource candidates.

[0325] According to a transmitting device in an embodiment of the present disclosure, wherein the first scheduling allocation indicates radio resources reserved for transmitting the second scheduling allocation at a later point in time: when the first scheduling allocation reserves radio resources that can be used by the transmitting device to transmit second data at a later point in time, or by including the following information: the first scheduling allocation reserves radio resources for transmitting the second scheduling allocation at a later point in time.

[0326] According to a sending device in an embodiment of the present disclosure, the sending device is configured by a radio base station, and the radio base station controls the sending device to reserve or not reserve radio resources for transmitting a second scheduled allocation at a later time point, optionally, wherein the configuration is performed by a message broadcast by the radio base station in the cell where the sending device is located, or by a dedicated message transmitted by the radio base station to the sending device, optionally, wherein the configuration regarding reserving or not reserving radio resources for transmission of the scheduled allocation is separate for each of a plurality of resource pools, and the plurality of resource pools can be used by the sending device to select radio resources for transmitting the scheduled allocation.

[0327] According to a sending device in an embodiment of the present disclosure, wherein the sending unit retransmits a first scheduling allocation once or multiple times within a transmission window, wherein the processing unit determines the number of retransmissions based on the priority of the first data and / or the congestion level of the side link interface, optionally wherein the processing unit performs an autonomous radio resource allocation process based on information obtained through a resource sensing process during the sensing window to select radio resources within the transmission window for one or more retransmissions of the first scheduling allocation, optionally wherein the first transmission of the first scheduling allocation and the one or more retransmissions of the first scheduling allocation include a public identifier to allow association of the first transmission and retransmission of the first scheduling allocation, optionally wherein the public identifier identifies the sending device and / or the data service of the sending device that generates the first data, optionally wherein the one or more retransmissions of the first scheduling allocation have a predetermined relationship with the first transmission of the first scheduling allocation.

[0328] A non-limiting embodiment of the present disclosure provides a method for a transmitting device, the transmitting device being used to transmit a scheduling allocation and data to one or more receiving devices via a sidelink interface, wherein the method includes the following steps performed by the transmitting device: performing a resource sensing process to obtain information about radio resources that the transmitting device can use to transmit the scheduling allocation at a later point in time, performing an autonomous radio resource allocation process after first data becomes available for transmission to select radio resources within a transmission window for transmitting the first data based on the information obtained by the resource sensing process during the sensing window before the first data becomes available for transmission, and selecting radio resources within the transmission window for transmitting the first scheduling allocation, wherein the first scheduling allocation includes information about the selected radio resources for transmitting the first data in the transmission window, transmitting the first scheduling allocation using the selected radio resources, and transmitting the first data using the selected radio resources, and wherein the first scheduling allocation also indicates reserved radio resources, which can be used by the transmitting device at a later point in time to transmit a second scheduling allocation for second data.

[0329] According to a method in an embodiment of the present disclosure, wherein the autonomous radio resource allocation performed to select radio resources within a transmission window to be used for transmitting a first scheduled allocation includes: preferentially selecting radio resources in a primary subframe of the transmission window relative to radio resources in a secondary subframe of the transmission window, and wherein the secondary subframes in the transmission window correspond to those subframes in the sensing window in which the transmitting device does not perform a resource sensing process, and the primary subframes in the transmission window correspond to those subframes in the sensing window in which the transmitting device performs a resource sensing process, optionally wherein the method includes determining the secondary subframes as those subframes of the transmission window in which the resource sensing process does not obtain all possible information during the sensing window, optionally wherein the loss information of the secondary subframes includes: possible reservations of radio resources by other transmitting devices during subframes in the sensing window in which the transmitting device does not perform a resource sensing process, optionally wherein the determination of the secondary subframes is based on possible periods of radio resource reservations that can be made by other transmitting devices, and / or information about received signal energy in radio resources of subframes in the sensing window in which the transmitting device does not perform a resource sensing process.

[0330] According to a method in an embodiment of the present disclosure, the autonomous radio resource allocation performed to select radio resources within a transmission window to be used for transmitting a first scheduling allocation also includes: determining one or more primary transmission radio resource candidates within a primary subframe, and optionally determining one or more secondary transmission radio resource candidates within a secondary subframe, in the case where there is more than one primary transmission radio resource candidate, the method includes performing candidate ranking of the primary transmission radio resource candidates, and in the case where there is more than one secondary transmission radio resource candidate, the method includes performing candidate ranking of the secondary transmission radio resource candidates, wherein the candidate ranking of the one or more primary transmission radio resource candidates is separate from the ranking of the one or more secondary transmission radio resource candidates.

[0331] According to a method in an embodiment of the present disclosure, the first scheduling allocation indicates radio resources reserved for transmitting the second scheduling allocation at a later point in time: when the first scheduling allocation reserves radio resources that can be used by the sending device to transmit the second data at a later point in time, or by including the following information: the first scheduling allocation reserves radio resources for transmitting the second scheduling allocation at a later point in time.

[0332] According to the method in an embodiment of the present disclosure, the transmitting device is configured by a radio base station, and the radio base station controls the transmitting device to reserve or not reserve radio resources for transmitting a second scheduled allocation at a later time point, optionally, wherein the configuration is performed by a message broadcast by the radio base station in the cell where the transmitting device is located, or by a dedicated message transmitted by the radio base station to the transmitting device, optionally, wherein the configuration regarding reserving or not reserving radio resources for transmission of the scheduled allocation is separate for each of a plurality of resource pools, and the plurality of resource pools can be used by the transmitting device to select radio resources for transmitting the scheduled allocation.

[0333] According to the method in an embodiment of the present disclosure, it also includes: retransmitting the first scheduling allocation once or multiple times within the transmission window, wherein the method also includes determining the number of retransmissions based on the priority of the first data and / or the congestion level of the side link interface, optionally, wherein the method includes performing an autonomous radio resource allocation process based on information obtained through a resource sensing process during the sensing window to select radio resources within the transmission window for one or more retransmissions of the first scheduling allocation, optionally, wherein the first transmission of the first scheduling allocation and the one or more retransmissions of the first scheduling allocation include a public identifier to allow association of the first transmission and retransmission of the first scheduling allocation, optionally, wherein the public identifier identifies the sending device and / or the data service of the sending device that generates the first data, optionally, wherein the one or more retransmissions of the first scheduling allocation have a predetermined relationship with the first transmission of the first scheduling allocation.

Claims

1. A transmitting device for determining radio resources to be used for data transmission from the transmitting device to one or more receiving devices via a sidelink interface, wherein the transmitting device comprises: a receiving unit and a processing unit which perform a resource sensing procedure in order to select radio resources which the sending device can use to transmit data at a later point in time, After data transmission is triggered, the processing unit performs autonomous radio resource allocation to select radio resources within a transmission window to be used for transmitting the data based on a result of the resource sensing process during a sensing window before the data transmission is triggered, and wherein the autonomous radio resource allocation comprises selecting radio resources in a primary subframe of the transmission window relative to radio resources in a secondary subframe of the transmission window, and The secondary subframes in the transmission window correspond to those subframes in the sensing window in which the transmitting apparatus does not perform the resource sensing process, and the primary subframes in the transmission window correspond to those subframes in the sensing window in which the transmitting apparatus performs the resource sensing process; The transmission window starts after the data transmission is triggered.

2. The transmitting device according to claim 1, wherein The resource sensing process includes: To determine the radio resources reserved by other transmitting devices, the receiving unit and the processing unit monitor scheduling information transmitted by other transmitting devices, the scheduling information indicating the radio resources reserved by the other transmitting devices for a later point in time, • Measuring received signal energy in radio resources in order to identify radio resources used for transmission by other transmitting devices.

3. The transmitting device according to claim 1 or 2, wherein: The processing unit determines the secondary subframes as those subframes of the transmission window for which the resource sensing process does not acquire all possible information during the sensing window, The loss information of the secondary subframe includes: possible reservation of radio resources by other transmitting devices during subframes in the sensing window in which the transmitting device does not perform the resource sensing procedure, wherein the determination of the secondary subframe is based on possible periods of radio resource reservation that can be made by the other transmitting devices, and / or Information on received signal energy in radio resources of subframes in the sensing window in which the transmitting device does not perform the resource sensing process.

4. The transmitting device according to claim 1, wherein The autonomous radio resource allocation further comprises determining one or more primary transmission radio resource candidates within the primary subframe, and determining one or more secondary transmission radio resource candidates within the secondary subframe, and in a case where there is more than one primary transmission radio resource candidate, the processing unit performs candidate ranking of the primary transmission radio resource candidate, and in a case where there is more than one secondary transmission radio resource candidate, the processing unit performs candidate ranking of the secondary transmission radio resource candidate, wherein the candidate ranking of the one or more primary transmission radio resource candidates is separate from the ranking of the one or more secondary transmission radio resource candidates, wherein the candidate ranking considers the temporal distance of the radio resource candidates from the time point when the data transmission is triggered, and the received signal energy prediction for the radio resource to be ranked obtained through the resource sensing process, The received signal energy prediction for the radio resource to be ranked is based on measurements of received signal energy of the corresponding radio resource in all subframes of the sensing window, or based on measurements of received signal energy of the corresponding radio resource in subframes of the sensing window that are related to the subframes of the radio resource to be ranked, wherein the related subframes are those subframes of the sensing window that have a distance from the radio resource to be ranked that is a multiple of a possible transmission period by other transmitting devices, The candidate ranking first considers the time distance and then the received signal energy, or the candidate ranking first considers the received signal energy and then the time distance, or the candidate ranking is based on a function of the time distance and the received signal energy.

5. The transmitting device according to claim 1 or 2, wherein: When data transmission or scheduling allocation transmission for data transmission is performed in a subframe, the transmitting device does not perform the resource sensing process in the subframe.

6. The transmitting device according to claim 1 or 2, wherein: In a case where no radio resources can be selected for transmission of the data, the processing unit determines to discard the data if the priority of the triggered data transmission is lower than a preemption priority threshold, and in a case where the data is not discarded, the processing unit performs a resource preemption procedure to select a radio resource to be used for transmission of the data from among radio resources reserved by one or more other transmitting devices. Wherein, when executing the resource preemption process, the processing unit selects the radio resources to be used for the transmission of the data based on the following: the priority of the reserved radio resources, and / or the priority of the data to be transmitted, and / or the received signal energy measured by the resource sensing process in the radio resources of the corresponding subframe in the sensing window, wherein the selection of radio resources in the resource preemption process first considers the priority of the reserved radio resources and then the received signal energy of the reserved radio resources, or first considers the received signal energy of the reserved radio resources and then the priority of the reserved radio resources, or is based on a function of the priority of the reserved radio resources and the received signal energy.

7. The transmitting device according to claim 1 or 2, wherein: The receiving unit and the processing unit determine a channel busy ratio of the sidelink interface, the channel busy ratio indicating a congestion level of the sidelink interface, and wherein the processing unit performs a data discard procedure to determine whether a triggered data transmission should be discarded based on the determined channel busy ratio of the sidelink interface before performing the autonomous radio resource allocation, and wherein the processing unit performs the autonomous radio resource allocation if the processing unit determines not to discard the data. wherein during the data discarding process, the processing unit discards the data when determining that the priority of the triggered data transmission is lower than a channel priority threshold, the channel priority threshold being dependent on the determined channel busy ratio of the sidelink interface, wherein the transmitting device is configured by a radio base station, the radio base station controlling the transmitting device to perform or not perform the data discarding process, wherein the configuration of the data discarding process is separate for each of a plurality of resource pools, the plurality of resource pools being usable by the transmitting device to select radio resources for transmitting data, The channel priority threshold also depends on the type of the triggered data transmission, wherein the channel priority threshold associated with safety data is lower than the channel priority threshold associated with non-safety data.

8. The transmitting device according to claim 1 or 2, wherein: The autonomous radio resource allocation includes excluding the radio resources reserved by the other transmitting devices from the radio resources to be used for the data transmission, and / or The radio resource candidates within the subframe include one or more resource blocks that are continuous in the frequency domain.

9. The transmitting device according to claim 1 or 2, wherein: the sensing window considered for the autonomous radio resource allocation comprises frequency-time radio resources starting at a predetermined point in time before the data transmission is triggered and ending at the point in time when the data transmission is triggered, and The transmission window includes frequency-time radio resources that start at a start subframe immediately after the subframe in which the data transmission is triggered and end at a subframe at a predetermined distance from the start subframe, wherein the distance depends on the delay requirement for the triggered data transmission that the sending device must meet.

10. A method for a transmitting device, the transmitting device being configured to determine radio resources to be used for data transmission from the transmitting device to one or more receiving devices via a sidelink interface, wherein the method comprises the following steps performed by the transmitting device: performing a resource sensing process to select a radio resource that the sending device can use to transmit data at a later point in time, After data transmission is triggered, autonomous radio resource allocation is performed to select radio resources within a transmission window to be used for transmitting the data based on a result of the resource sensing process during a sensing window before the data transmission is triggered, in, The autonomous radio resource allocation comprises selecting radio resources in a primary subframe of the transmission window relative to radio resources in a secondary subframe of the transmission window, and The secondary subframes in the transmission window correspond to those subframes in the sensing window in which the transmitting apparatus does not perform the resource sensing process, and the primary subframes in the transmission window correspond to those subframes in the sensing window in which the transmitting apparatus performs the resource sensing process; The transmission window starts after the data transmission is triggered.

11. An integrated circuit that controls a process of a transmitting device for determining radio resources to be used for data transmission from the transmitting device to one or more receiving devices via a sidelink interface, wherein the process comprises the following processes performed by the transmitting device: performing a resource sensing process to select radio resources available to the transmitting device for transmitting data at a later point in time, After data transmission is triggered, autonomous radio resource allocation is performed to select radio resources within a transmission window to be used for transmitting the data based on a result of the resource sensing process during a sensing window before the data transmission is triggered, in, The autonomous radio resource allocation comprises selecting radio resources in a primary subframe of the transmission window relative to radio resources in a secondary subframe of the transmission window, and The secondary subframes in the transmission window correspond to those subframes in the sensing window in which the transmitting apparatus does not perform the resource sensing process, and the primary subframes in the transmission window correspond to those subframes in the sensing window in which the transmitting apparatus performs the resource sensing process; The transmission window starts after the data transmission is triggered.

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