RU2734102C1 - Improved probing and selection of radio communication resources for v2x transmissions - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: invention relates to the field of transmitting devices, which performs resource probing procedure to obtain information on radio communication resources, which can be used for data transmission at a later moment in time. After the data become available for transmission, the transmitting device performs independent radio resource allocation to select radio resources in the transmission window, which must be used for data transmission, based on information obtained through the procedure of probing resources during the probing window. Autonomous distribution of radio communication resources comprises selection of radio communication resources in primary subframes of transmission window, preferably over radio resources in secondary subframes of transmission window. Secondary subframes correspond to those subframes in the probing window, during which the transmitting device did not perform the resource probing procedure, and the primary subframes correspond to those subframes in the probing window during which the transmitting device has performed the resource probing procedure.

EFFECT: technical result is to increase the efficiency of communication.

9 cl, 18 dwg

Description

TECHNICAL FIELD OF THE INVENTION

The present invention relates to improved transmitters for performing sensing and radio resource selection. The present invention provides suitable methods and apparatus for the invention.

PRIOR ART

Long Term Evolution (LTE)

Third generation (3G) mobile systems based on WCDMA radio access technology are deployed on a large scale around the world. The first phase of improvement or development of this technology entails the introduction of High Speed Downlink Packet Access (HSDPA) and an improved uplink, also referred to as High Speed Uplink Packet Access (HSUPA), providing a radio access technology that is very competitive.

In order to be prepared for further growing user needs and to be competitive with new radio access technologies, 3GPP has introduced a new mobile communication system called Long Term Evolution (LTE). LTE is designed to meet the carrier's needs for high-speed media and data transport, as well as support high-capacity voice communications for the next decade. The ability to provide high bit rates is a key feature of LTE.

The Long Term Evolution (LTE) Working Question (WI), which is called UMTS Terrestrial Radio Access Evolved (UTRA) and UMTS Terrestrial Radio Access Network (UTRAN), has ended as Revision 8 (LTE Rel. 8). The LTE system is an efficient packet-based radio access and radio access networks that provide full IP-based functionality with low latency and low cost. In LTE, scalable multiple transmission bandwidths such as 1.4, 3.0, 5.0, 10.0, 15.0, and 20.0 MHz are specified in order to achieve flexible system deployment using a specific spectrum. In the downlink, an Orthogonal Frequency Division Multiplexing (OFDM) based radio access has been used because of its inherent robustness to multipath interference (MPI) due to its low symbol rate, the use of a cyclic prefix (CP), and its affinity with different bandwidth arrangements transmission. Frequency division multiple access, single carrier radio access has been used in the uplink since providing wide coverage has been prioritized over improving peak data rates given the limited transmit power of the user equipment (UE). Many key packet radio access techniques are used, including multiple-input multiple-output (MIMO) channel transmission techniques, and a highly efficient control signaling structure is achieved in LTE Rel. 8/9.

LTE architecture

The general architecture of LTE is shown in FIG. 1. E-UTRAN consists of an eNodeB providing E-UTRA user plane (PDCP / RLC / MAC / PHY) and control plane (RRC) 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 the user plane header compression and encryption functionality. It also offers Radio Resource Control (RRC) functionality corresponding to the control plane. It performs many functions, including radio resource management, admission control, scheduling, uplink quality of service (QoS) enforcement, cell broadcast, user and control plane data encryption / decryption, and downstream user plane packet header compression / decompression. communication lines / uplinks. eNodeBs are interconnected with each other via an X2 interface.

The eNodeBs are also connected via the S1 interface to the EPC (Evolved Packet Core), in particular to the MME (Mobility Management Entity) via the S1-MME and the Serving Gateway (SGW) via the 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 while also acting as a mobility anchor for the user plane during inter-eNodeB handoffs and as a mobility anchor between LTE and other 3GPP technologies (terminating the S4 interface and relaying traffic between 2G / 3G and PDN GW). For idle UEs, the SGW terminates the downlink data path and initiates a paging call when the downlink data arrives for the UE. It administers and stores user equipment contexts such as IP bearer service parameters or routing information internal to the network. It also duplicates user traffic in the event of a legitimate interception.

MME is a key control node for an LTE access network. It is responsible for monitoring and paging the idle user equipment, including retransmissions. It is involved in the bearer activation / deactivation process and is also responsible for the selection of the SGW for the user equipment upon initial attachment and during intra-LTE handover involving Core Network (CN) node relocation. It is responsible for authenticating the user (through interaction with the HSS). No Access Layer Signaling (NAS) terminates at the MME, and it is also responsible for generating and distributing temporary credentials to user equipments. It checks the authorization of the user equipment to anchor in the service provider's PLMN and enforces roaming restrictions of the user equipment. The MME is the network termination point for encryption / integrity protection for NAS signaling and provides security key management. Lawful interception of signaling is also supported by the MME. The MME also provides a control plane function for mobility between LTE and 2G / 3G access networks, terminating the S3 interface in the MME from the SGSN. The MME also terminates the S6a interface towards the home HSS for roaming user equipments.

Component carrier structure in LTE

поднесущих и

OFDM-символов.

является числом блоков ресурсов в рамках полосы пропускания. Количество

зависит от полосы пропускания передачи нисходящей линии связи, сконфигурированной в соте, и должно удовлетворять

, где

и

являются соответственно наименьшей и наибольшей полосами пропускания нисходящей линии связи, которые поддерживаются текущей версией технического описания.

является числом поднесущих в рамках одного блока ресурсов. Применительно к структуре субкадра с нормальным циклическим префиксом,

.The downlink component carrier of the 3GPP LTE system is subdivided in the time-frequency domain into so-called subframes. In 3GPP LTE, each subframe is divided into two downlink slots as shown in FIG. 2, wherein the first downlink slot comprises a control channel area (PDCCH area) within the first OFDM symbols. Each subframe consists of a specific number of OFDM symbols in the time domain (12 or 14 OFDM symbols in 3GPP LTE (Revision 8)), with each OFDM symbol covering the entire bandwidth of the component carrier. Thus, each of the OFDM symbols consists of a number of modulation symbols that are transmitted on the respective subcarriers. In LTE, the transmitted signal in each slot is described by a resource grid from

subcarriers and

OFDM symbols.

is the number of resource blocks within the bandwidth. number

depends on the downlink transmission bandwidth configured in the cell and must satisfy

where

and

are respectively the lowest and highest downlink bandwidths supported by the current version of the technical specification.

is the number of subcarriers within one resource block. Applied to the normal cyclic prefix subframe structure,

...

Assuming a multi-carrier communication system such as using OFDM such as used in 3GPP Long Term Evolution (LTE), the smallest unit of resources that can be assigned by the scheduler is one “resource block”. A physical resource block (PRB) is defined as successive OFDM symbols in the time domain (eg, 7 OFDM symbols) and successive subcarriers in the frequency domain, as exemplified in FIG. 2 (for example, 12 subcarriers per component carrier). In 3GPP LTE (Revision 8), a physical resource block is thus composed of 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, for example, 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, available at http://www.3gpp.org and incorporated herein by links).

One subframe consists of two slots, so there are 14 OFDM symbols in a subframe when a so-called "normal" CP (cyclic prefix) is used and 12 OFDM symbols in a subframe when a so-called "extended" CP is used. For the sake of terminology, in the following, time-frequency resources equivalent to the same consecutive subcarriers spanning a full subframe are referred to as a “resource block pair”, or equivalently an “RB pair” or “PRB pair”.

The term "component carrier" refers to the combination of multiple resource blocks in the frequency domain. In future LTE revisions, the term “component carrier” is no longer used; instead, the terminology is changed to "cell", which refers to a combination of downlink and optionally uplink resources. The association between the carrier of the downlink resources and the carrier of the uplink resources is indicated in the system information that is transmitted on the downlink resources.

Similar assumptions about the component carrier structure will apply to later revisions as well.

LTE-A carrier aggregation for higher bandwidth

The decision on the frequency spectrum for Enhanced-IMT was taken at the World Radiocommunication Conference 2007 (WRC-07). Although a decision has been made on the overall frequency spectrum for Enhanced-IMT, the actual available frequency bandwidth varies according to each region or country. Following the decision on the available frequency spectrum structure, however, the standardization of the radio interface has begun in the 3rd Generation Partnership Project (3GPP). At 3GPP TSG RAN # 39, the Study Subject Description for Further Advancements for EUTRA (LTE-Advanced) was approved. The subject matter of the study covers technological components that need to be considered for the development of E-UTRA, for example, to meet the requirements of Enhanced-IMT.

The bandwidth that LTE-Enhanced system can support is 100MHz, while the LTE system can only support 20MHz. Nowadays, the lack of radio spectrum has become a bottleneck in the development of wireless networks, and as a result, it is difficult to find a spectrum band that is wide enough for the Advanced-LTE system. As a consequence, it is necessary to find a way to obtain a wider radio spectrum bandwidth, with the possible answer being the carrier aggregation functionality.

With carrier aggregation, two or more component carriers are aggregated in order to support wider transmission bandwidths, up to 100MHz. Aggregation of several cells in the LTE system is carried out into one wider channel in the Advanced-LTE system, which is wide enough for 100 MHz, even though these cells in LTE may be in different frequency bands.

All component carriers can be configured to be compatible in LTE Rel. 8/9 at least when the bandwidth of the component carrier does not exceed the supported bandwidth of the LTE Rel. 8/9 honeycomb. It is not necessary that all of the constituent carriers that are aggregated by the user equipment may be Rel. 8/9. Existing mechanisms (eg, barring) can be used to prevent Rel-8/9 user equipments from being anchored in the component carrier.

User equipment can simultaneously transmit and receive on one or more component carriers (corresponding to multiple component carriers), depending on its capabilities. User equipment LTE-A Rel. 10 with reception and / or transmission capabilities in relation to carrier aggregation can simultaneously receive and / or transmit over several serving cells, while LTE Rel. 8/9 can transmit and receive on only one serving cell, provided that the component carrier structure follows the Rel. 8/9.

Carrier aggregation is supported for both contiguous and non-contiguous component carriers, with each component carrier being limited to a maximum of 110 Resource Blocks in the frequency domain (using 3GPP LTE numerology (Revision 8/9).

It is possible to configure 3GPP LTE-A (Revision 10) -compatible user equipment to aggregate a different number of component carriers originating from the same eNodeB (base station) and possibly different bandwidths in the uplink and downlink. The number of downlink component carriers that can be configured depends on the downlink aggregation capability of the UE. Conversely, the number of uplink component carriers that can be configured depends on the UE's uplink aggregation capability. At present, it is not possible to configure a mobile terminal with the number of uplink component carriers greater than the number of downlink component carriers. In a typical TDD deployment, the number of component carriers and the bandwidth of each component carrier in the uplink and downlink are the same. Component carriers originating from the same eNodeB do not necessarily provide the same coverage.

The distance between the center frequencies of the adjacent aggregated carrier components should be a multiple of 300 kHz. This is in order to be compatible with the 100kHz 3GPP LTE Frequency Pattern (Revision 8/9) and at the same time maintain the orthogonality of subcarriers with 15kHz spacing. Depending on the aggregation scenario, n × 300 kHz distance can be achieved by inserting a low number of unused sub-carriers between adjacent component carriers.

The multi-carrier aggregation nature is only available up to the MAC layer. For both the uplink and the downlink, there is only one HARQ entity required in the MAC for each aggregated component carrier. The largest single transport block per component carrier is present (in the absence of uplink SU-MIMO). The transport block and its potential HARQ retransmissions should be mapped to the same component carrier.

When the carrier aggregation is configured, the mobile terminal has only one RRC connection to the network. When creating / re-establishing an RRC connection, one cell provides security input (one ECGI, one PCI and one ARFCN) and non-access layer mobility information (eg TAI) similar to LTE Rel. 8/9. After creation / re-establishment of the RRC connection, the constituent carrier corresponding to that cell is referred to as the Downlink Primary Cell (PCell). There is always one and only one downlink PCell (DL PCell) and one uplink PCell (UL PCell) configured for the user equipment in the connected state. Within the configured component carrier set, the other cells are referred to as Secondary Cells (SCell); with SCell carriers being the Secondary Downlink Component Carrier (DL SCC) and the Secondary Uplink Component Carrier (UL SCC). A maximum of five serving cells, including PCell, can be configured for one UE.

MAC layer / object, RRC layer, Physical layer

The LTE Layer 2 user / control plane protocol stack contains four sublayers, RRC, PDCP, RLC, and MAC. The Media 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, 3GPP TS 36.321, current version 13.2.0. The connection to the physical layer below is carried out via transport channels, and the connection to the RLC layer above is carried out via logical channels. As a consequence, the MAC layer performs multiplexing and demultiplexing between logical channels and transport channels: the MAC layer on the transmitting side creates MAC PDUs, known as transport blocks, from MAC SDUs received through the logical channels, and the MAC layer on the receiving side recovers the MAC SDU from the MAC PDU. received through transport channels.

The MAC layer provides a data bearer service (see sub-clauses 5.4 and 5.3 of TS 36.321, incorporated herein by reference) for the RLC layer through logical channels, which are either logical control channels that carry control data (e.g., RRC signaling) or logical traffic channels that carry user plane data. On the other hand, data exchange from the MAC layer is carried out with the physical layer through transport channels, which are classified as downlink or uplink. The data is multiplexed into transport channels depending on how it is transmitted over the radio interface.

The Physical Layer is responsible for the actual transmission of data and control information over the air interface, i.e., the Physical Layer carries all information from the MAC transport channels through the air interface on the transmission side. Some of the 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 (within LTE system and between systems) for RRC layer. The physical layer performs transmissions 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 on the functioning of the physical layer can be found in 3GPP technical standard 32.213, current version 13.1.1, which is incorporated herein by reference.

The Radio Resource Control (RRC) layer manages communication between the UE and the eNB over the air interface and the mobility of the UE that roams across multiple cells. RRC also supports the transfer of NAS information. For a UE in the RRC_IDLE state, RRC supports notification from the network of incoming calls. RRC connection management covers all procedures related to the creation, modification and release of an RRC connection, including paging, configuration and measurement reporting, configuration of radio resources, initial security activation, and creation of signaling radio bearer (SRB) and radio bearers. carrying user data (radio data carriers, DRB).

The radio link control (RLC) sublayer mainly contains ARQ functionality and supports data segmentation and concatenation, i. E. The RLC layer framing the RLC SDUs to fit in the size specified by the MAC layer. The latter two minimize protocol losses regardless of the data transfer rate. The RLC layer is connected to the MAC layer through logical channels. Each logical channel carries different types of traffic. The layer above the RLC layer is usually the PDCP layer, but in some cases it is the RRC layer, i.e., RRC messages transmitted on the logical channels BCCH (Broadcast Control Channel), PCCH (Paging Control Channel) and CCCH ( Shared Control Channel) do not require security and thus go directly to the RLC layer bypassing the PDCP layer.

Uplink access scheme for LTE

In the context of transmission, power efficient transmission of a user terminal is needed to maximize coverage. Single carrier transmission combined with dynamic bandwidth allocation FDMA was chosen as the evolved UTRA uplink transmission scheme. The main reason for the preference for single carrier transmission is 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 certain terminal peak power). During each slot, the eNodeB assigns a unique time / frequency resource to users to transmit user data, thereby ensuring intra-cellular orthogonality. Uplink orthogonal access promises increased spectral efficiency by eliminating intra-cellular interference. Multipath interference is handled at the base station (eNodeB) by inserting a cyclic prefix into the transmitted signal.

The basic physical resource used for data transmission consists of a frequency resource of BWgrant size for one time interval, for example, a subframe in which encoded information bits are displayed. It should be noted that a subframe, also referred to as a transmission time interval (TTI), is the smallest time interval for transmitting user data. However, it is possible to assign the frequency resource BWgrant over a longer time period than one TTI for the user by concatenating subframes.

Layer 1 / Layer 2 control signaling

In order to inform scheduled users of their allocation status, transport format, and other transmission related information (eg, HARQ information, transmit power control (TCP) commands), L1 / L2 control signaling is transmitted along the downlink along with the data. The L1 / L2 control signaling is multiplexed with the downlink data in a subframe, assuming that the user allocation may vary from subframe to subframe. It should be noted that user allocation can also be performed based on TTI (Transmission Time Interval), where the TTI length can be multiples of subframes. The TTI length can be fixed in the service area for all users, it can be different for different users, or it can even be dynamic for each user. In general, the L1 / L2 control signaling is required to be transmitted only once per TTI. Without loss of generality, the following assumes that the TTI is equivalent to one subframe.

L1 / L2 control signaling is carried on the Physical Downlink Control Channel (PDCCH). The PDCCH carries a message as Downlink Control Information (DCI), which in most cases includes resource assignments and other control information for a mobile terminal or UE group. Several PDCCHs can be transmitted in one subframe.

In general, the information sent in the L1 / L2 control signaling for the assignment of uplink or downlink radio resources (in particular LTE (-A) Revision 10) can be classified into the following elements:

- User credentials indicating the user who is being shared. This is typically included in the checksum by masking the CRC with user credentials;

- Resource allocation information indicating resources (eg, Resource Blocks, RBs) to which the user is allocated. Alternatively, this information is referred to as resource block assignment (RBA). Note that the number of RBs over which the user is allocated may be dynamic;

- Carrier indicator, which is used if the control channel transmitted on the first carrier assigns resources that relate to the second carrier, i.e., resources on the second carrier or resources associated with the second carrier; (planning between carriers);

- Modulation and coding scheme, which defines the modulation scheme used and coding rate;

- HARQ information such as new data indicator (NDI) and / or redundancy version (RV), which are particularly used in retransmissions of data packets or portions thereof;

- Power control commands to adjust the transmission power of the assigned data transmission or uplink control information;

- Information of the reference signal, such as the applied cyclic shift and / or the index of the orthogonal code of the coverage, which should be used for transmitting or receiving reference signals related to the assignment;

- An uplink or downlink assignment index, which is used to identify the order of assignments, which is particularly useful in TDD systems;

- Information hopping, for example, an indication of whether and how resource hopping is applied in order to increase frequency diversity;

- A CSI request that is used to initiate the transmission of channel state information on the assigned resource; and

- Multi-cluster information, which is a flag used to indicate and control whether transmission occurs in one cluster (contiguous set of RBs) or across multiple clusters (at least two non-contiguous sets of contiguous RBs). Multi-cluster distribution was introduced by 3GPP LTE- (A) Revision 10.

It should be noted that the above is not exhaustive, and it is not required that all of the aforementioned pieces of information be present in every PDCCH transmission depending on the DCI format that is used.

Downlink control information takes place in several formats that differ in overall size as well as information contained in their fields, as mentioned above. The various DCI formats that are 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 v13.1.0, available at http: // www. 3gpp.org and is incorporated herein by reference). 3GPP TS 36.212, current version 13.1.0, defines in Subclause 5.4.3, which is incorporated herein by reference, control information for a sidelink interface.

Semi-permanent scheduling (SPS)

In the downlink and uplink, the scheduling eNodeB dynamically allocates resources to the user equipments in each transmission time slot over the L1 / L2 control channel (s) (PDCCH), where the user equipments are addressed through their specific C-RNTI. As mentioned previously, the CRC of the PDCCH is masked with the C-RNTI of the addressable user equipment (so called dynamic PDCCH). Only one user equipment with a matching C-RNTI can decode the PDCCH content correctly, i.e., the CRC is positive. This kind of PDCCH signaling is also referred to as dynamic (scheduling) grant. The user equipment monitors each L1 / L2 control channel transmission time slot for dynamic grant in order to find a possible allocation (downlink or uplink) that is assigned to it.

In addition, the E-UTRAN can allocate uplink / downlink resources for initial HARQ transmissions in a persistent manner. Retransmissions are explicitly signaled through the L1 / L2 control channel (s) when required. Since retransmissions are dynamically scheduled, this kind of work is referred to as semi-persistent scheduling (SPS), i.e. resources are allocated to the user equipment on a semi-persistent basis (semi persistent resource allocation). The advantage is that PDCCH resources are conserved for the initial HARQ transmissions. Semi-permanent scheduling can be used in PCell Edition 10, but not in SCell.

One example of a service that can be scheduled using semi-persistent scheduling is Voice over IP (VoIP). Every 20ms a VoIP packet is generated in the codec during the speech stream. As a consequence, the eNodeB can allocate uplink resources and thus downlink resources in a constant manner every 20ms, which can then be used to transmit Voice packets over IP. In general, semi-persistent scheduling is beneficial for services with predictable traffic behavior, i.e. constant bit rate, packet arrival time is periodic.

The user equipment also monitors the PDCCH in a subframe in which resources for initial transmission have been allocated in a persistent manner. Dynamic (planning) resolution, i.e. PDCCH with C-RNTI-masked CRC can cancel semi-persistent resource allocation. In the event that the user equipment finds its C-RNTI on the L1 / L2 control channel (s) in subframes in which the user equipment has assigned semi-persistent resources, this L1 / L2 control channel allocation cancels the persistent resource allocation for that transmission time slot, and user equipment follows dynamic resolution. When the user equipment does not find a dynamic grant, it will transmit / receive according to a semi-persistent resource allocation.

The configuration of semi-persistent scheduling is performed by RRC signaling. For example, a periodicity, such as PS_PERIOD, of a persistent allocation is signaled as part of Radio Resource Control (RRC) signaling. Permanent allocation activation, as well as fine timing, as well as physical resources and transport format parameters, are sent via PDCCH signaling. Once the semi-persistent scheduling is activated, the user equipment follows the semi-persistent resource allocation in accordance with the PDCCH by SPS activation every PS_PERIOD. As such, the user equipment stores the contents of the SPS activation PDCCH and follows the PDCCH at a signaled frequency.

In order to distinguish a dynamic PDCCH from a PDCCH that activates semi-persistent scheduling (hereinafter referred to as SPS activation PDCCH), separate identification data are entered. Basically, the CRC of the SPS activation PDCCH is masked with this additional identification, which in the following are referred to as SPS C-RNTI. The SPS C-RNTI size is also 16 bits, just like the normal C-RNTI. In addition, the SPS C-RNTI is also user equipment specific, i.e. each user equipment that is configured for semi-persistent scheduling is allocated a unique SPS C-RNTI.

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

Similar to enabling semi-persistent scheduling, the eNodeB can also disable semi-persistent scheduling, also referred to as SPS resource release. There are several options for how cancellation of the semi-persistent scheduling allocation can be signaled. One option would be to use PDCCH signaling with some PDCCH fields set to some predefined values, i. E. SPS PDCCH indicating resource allocation of size zero. Another option would be to use MAC control signaling.

Device-to-Device (D2D) Proximity Services (ProSe) LTE

Proximity-based applications and services represent an emerging socio-technological trend. The identified areas include services related to commercial services and Public Safety, which will be of interest to operators and users. The introduction of Proximity Services (ProSe) capability in LTE enables the 3GPP industry to serve this emerging market and, at the same time, will meet the pressing needs of several Public Safety associations that are jointly committed to LTE.

Device-to-Device (D2D) communication is a technology component introduced by LTE-Rel.12 that provides D2D as a substrate for the cellular network to increase spectral efficiency. For example, if the cellular network is LTE, then all data-carrying physical channels use SC-FDMA for D2D signaling. In D2D communications, user equipments transmit data signals to each other via a direct link using cellular resources instead of via a radio base station. Throughout the patent application, the terms "D2D", "ProSe" and "sidelink" are used interchangeably.

D2D communications in LTE are focused on two areas: Discovery and Communications. ProSe Direct Discovery (Proximity Based Services) is defined as the procedure used by a ProSe enabled UE to discover other ProSe UEs in its vicinity using direct E-UTRA radio signals over the PC5 interface.

In D2D communication, UEs transmit data signals to each other via a forward link using cellular resources instead of via a base station (BS). D2D users communicate directly while remaining under the control of the BS, ie at least in the coverage of the eNB. As a consequence, D2D can improve system efficiency by reusing cellular resources.

D2D is assumed to operate in the LTE uplink spectrum (in the case of FDD) or uplink subframes at the cell providing coverage (in the case of TDD, except when out of coverage). In addition, D2D transmit / receive does not use full duplex on a specific carrier. From the point of view of an individual UE, on a specific carrier, D2D signal reception and LTE uplink transmission do not use full duplex, i.e., simultaneous D2D signal reception and LTE UL transmission are not possible.

In D2D communication, when one particular UE1 plays 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 transmit and receive roles. The transmission from UE1 may be received by one or more UEs like UE2.

ProSe feed-forward layer-2 link

In short, direct one-to-one ProSe communication is implemented by creating a secure layer-2 link across PC5 between two UEs. Each UE has a unicast Layer-2 ID, which is included in the Source Layer-2 ID field of each frame that is sent on the layer-2 link and in the Recipient Layer-2 ID of each frame that is received on the layer-2 link. The UE needs to ensure that the Layer-2 ID for unicast communication is at least locally unique. Thus, the UE must be prepared to handle collisions of Layer-2 IDs with adjacent UEs using unspecified mechanisms (eg, self-assigning a new Layer-2 ID for unicast communication when a collision is detected). A layer-2 link for one-to-one ProSe direct communication is identified by the combination of the Layer-2 IDs of the two UEs. This means that the UE can be involved in multiple Layer-2 links for direct one-to-one ProSe communications using the same Layer-2 ID.

Direct One-to-One ProSe communication consists of the following procedures, as explained in detail in TR 23.713 current version v13.0.0 section 7.1.2, which is incorporated herein by reference:

- Creation of a secure communication line of layer-2 through PC5.

- Assigning an IP address / prefix.

- Providing layer-2 communication link via PC5.

- Release of the layer-2 communication link via PC5.

FIG. 3 illustrates how a secure layer-2 link is created over the PC5 interface.

1. The UE-1 sends a Forward Communication Request message to the UE-2 in order to initiate 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 may learn the Layer-2 ID from the peer by first performing the procedure discovery or by participating in one-to-many ProSe communications involving a peer.

2. The UE-2 initiates a mutual authentication procedure. Successful completion of the authentication procedure completes the creation of a secure layer-2 link through PC5.

UEs involved in isolated (no relay) one-to-one communications may also use link-local addresses. The PC5 Signaling Protocol must support keepalive functionality, which is used to detect when UEs are not in the ProSe Link range so that they can transition to an implicit release of the layer-2 link. Release of the layer-2 link via PC5 can be accomplished by using a Release Request message sent to another UE, which also deletes all associated context data. Upon receipt of the Disconnect Request message, the other UE responds with a Disconnect Reply message and deletes all context data associated with the layer-2 link.

Identity data associated with Direct ProSe Link

3GPP TS 36.300, current version 13.3.0, defines in subclause 8.3 the following identification data to use for Direct ProSe Communications:

- SL-RNTI: Unique identification used for ProSe Direct Link Scheduling;

- Source Layer-2 ID: Identifies the sender of data in a Direct ProSe Direct Connection. The Source Layer-2 ID is 24 bits in length and is used in conjunction with the ProSe Layer-2 Receiver ID and LCID to identify the I + UM RLC entity and the PDCP entity at the receiver;

- Recipient Layer-2 ID: Identifies the data target in a Direct ProSe Direct Connection. The Recipient Layer-2 ID is 24 bits in length and is split into two bit lines on the MAC layer:

- One bit string is the LSB part (8 bits) of the Recipient Layer-2 ID and is forwarded to the physical layer as the Layer-1 ID of the Direct Link Control. It identifies the target of the intended data in Direct Link Control and is used to filter packets on the physical layer.

- The second bit string is the MSB part (16 bits) of the Recipient Layer-2 ID and is carried within the MAC header. It is used to filter packets on the MAC layer.

No Access Layer Signaling is required to form the group, and to configure the Source Layer-2 ID, the Receiver Layer-2 ID and the Direct Connection Control L1 ID in the UE. These credentials are either provided by the top layer or extracted from the credentials provided by the top layer. In case of multicast and broadcast, the ProSe UE ID provided by the upper layer is used directly as the Source Layer-2 ID, and the ProSe Layer-2 Group ID provided by the upper layer is used directly as the Receiver Layer-2 ID in the MAC layer. ... In the case of one-to-one communication, the top layer provides the Source Layer-2 ID and the Receiver Layer-2 ID.

Allocation of radio resources for Proximity Services

From the point of view of the transmitting UE, the Proximity Services UE (ProSe UE) can operate in two modes for resource allocation:

Mode 1 refers to a scheduling eNB mode in which the UE requests transmission resources from the eNB (or Revision 10 relay node) and the eNodeB (or Revision 10 relay node) in turn schedules the resources used by the UE to transmit immediate data and direct management information (eg Scheduling Assignment). The UE is required to be in the RRC_CONNECTED state in order to transmit data. In particular, the UE sends a scheduling request (D-SR or Random Access) to the eNB, followed by a buffer status report (BSR) of the direct connection in the usual way (see also the next chapter “Transfer Procedure for D2D Communication”). Based on the BSR, the eNB can determine that the UE has data for ProSe Direct Link transmission and can estimate the resources required for the transmission.

On the other hand, Mode 2 refers to a UE-autonomous resource selection mode in which the UE independently selects resources (time and frequency) from the resource pool (s) to transmit immediate data and immediate control information (i.e., SA). At least one resource pool is defined, for example, by the contents of SIB18, namely the commTxPoolNormalCommon field, this particular resource pool (s) being broadcast in the cell and then shared by all UEs in the cell even in the RRC_Idle state. In fact, the eNB can define up to four different instances of said pool, respectively four resource pools for the transmission of SA messages and direct data. However, in Rel-12, the UE must always use the first resource pool defined in the list, even if multiple resource pools have been configured. This limitation has been removed for Rel-13, ie, the UE can transmit on several of the configured resource pools within one SC period. How the UE selects resource pools for transmission is further described below (further indicated in TS36.321).

Alternatively, another resource pool can be defined by the eNB and signaled in SIB18, namely by using the commTxPoolExceptional field, which can be used by the UE in exceptional cases.

Which resource allocation mode the UE will use is configured by the eNB. In addition, which resource allocation mode 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 status of the UE, i.e. in coverage, outside coverage. A UE is considered to be in coverage if it has a serving cell (ie, the UE is RRC_CONNECTED, or anchored in a cell in RRC_IDLE).

FIG. 4 illustrates transmission / reception resource utilization for overlay (LTE) and substrate (D2D) systems.

Mainly, the eNodeB controls whether the UE can apply Mode 1 or Mode 2 transmission. Once the UE knows its resources on which it can transmit (or receive) D2D communication, it uses only the appropriate resources for the corresponding transmit / receive. For example, in FIG. 4 D2D subframes will only be used to receive or transmit D2D signals. Since the UE, as a D2D device, will operate in Half Duplex mode, it can either receive or transmit D2D signals at any time. Similarly, the other subframes illustrated in FIG. 4 can be used for LTE transmission and / or reception (overlay).

Transfer Procedure for D2D Communication

D2D data transfer procedure according to Rel. 12/13 differs depending on the resource allocation mode. As described above for Mode 1, the eNB explicitly schedules resources for the D2D Scheduling Assignment and Data Communication upon a corresponding request from the UE. In particular, the UE may be informed by the UE that D2D communication is generally allowed, but that Mode 2 resources (ie, resource pool) are not being granted; this could be done, for example, by exchanging a D2D Communication Indication of Interest by the UE and a corresponding response, D2D Communication Response, where the corresponding exemplary ProseCommConfig information item would not include commTxPoolNormalCommon, meaning that a UE that wishes to initiate a direct communication involving transmission shall request the E-UTRAN for resource assignments for each individual transmission. Thus, in such a case, the UE has to request resources for each individual transmission, and in the following, the different steps of the request / grant procedure are listed by way of example for a given Mode 1 resource allocation:

- Stage 1: UE sends SR (Scheduling Request) to the eNB via PUCCH;

- Step 2: the eNB allows the UL resource (for the UE to send the BSR of the direct connection) through the PDCCH encrypted with C-RNTI;

- Step 3: UE sends D2D / direct connect BSR indicating buffer status via PUSCH;

- Step 4: The eNB enables the D2D resource (for the UE to send data) through the PDCCH encrypted with D2D-RNTI.

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

The Scheduling Assignment (SA), also called SCI (Direct Attach Control Information), is a compact (low payload) message containing control information such as an indication (s) to time-frequency resources, modulation and coding scheme, and Group Recipient ID for appropriate D2D data transfer. SCI transports direct connection scheduling information for one recipient ID (ProSe). The SA (SCI) content is basically in accordance with the permission taken in Step 4 above. D2D resolution and SA content (i.e., SCI content) are defined in the 3GPP technical standard, current version 13.1.0, subclause 5.4.3, incorporated herein by reference, defining in particular format 0 SCI (see content format 0 SCI above).

On the other hand, for Resource Allocation Method 2, the above steps 1-4 are generally unnecessary and the UE autonomously selects radio resources for SA and D2D data transmission from the transmission resource pool (s) configured and provided by the eNB.

FIG. 5 illustrates by way of example the transmission of the Scheduling Assignment and D2D data for two UEs, UE-1 and UE-2, in which the resources for sending the scheduling assignments are periodic and the resources used for the D2D data transmission are indicated by the corresponding Scheduling Assignment.

FIG. 6 illustrates one specific example of D2D communication timing for Autonomous Scheduling Mode 2 during one SA / data period, also known as SC period, Direct Connection Control period. FIG. 7 illustrates the D2D communication timing for Mode 1 eNB scheduling during one SA / data period. In Rel. 13, 3GPP defines the SC period as a time period consisting of the transmission of the Scheduling Destination and its corresponding data. As can be seen from FIG. 6, the UE transmits, after the SA offset time, the Scheduling Assignment using transmission pool resources for the scheduling assignment for Mode 2, SA_Mode2_Tx_pool. The 1st SA transmission is followed, for example, by three retransmissions of the same SA message. Then, the UE starts transmitting the D2D data, i.e., more specifically the T-RPT bitmap / pattern, with some configured offset (Mode2data_offset) after the first subframe of the SA resource pool (which is set by SA_offset). One D2D data transmission of a MAC PDU (i.e., transport block) consists of its 1st initial transmission and several retransmissions. To illustrate, FIG. 6 (and FIG. 7), it is assumed that three retransmissions are performed (i.e., 2nd, 3rd and 4th transmission of the same MAC PDU). Bitmap T-RPT Mode2 (temporary transmission resources template, T-RPT) mainly determines the transmission timing MAC PDU (first transfer) and its retransmission (2 ^nd, 3 and 4 ^{s th} transmission). Template SA primarily determines the initial transmission timing SA and its retransmissions ((2 ^nd, 3 and 4 ^{s th} transmission).

As currently specified in the standard, for one direct connection permission, for example, either sent by the eNB or selected by the UE itself, the UE can transmit multiple transport blocks, MAC PDUs, (only one per subframe (TTI), i.e. i.e., one by one), however, only one group of ProSe recipients. Also, retransmissions of one transport block must be completed before the first transmission of the next transport block begins, ie, only one HARQ process is used to allow a direct connection to transmit multiple transport blocks. In addition, the UE may have and use multiple direct connection grants per SC period, but a different ProSe recipient is selected for each one. Thus, in one SC period, the UE can transmit data to one ProSe recipient only once.

As evident from FIG. 7, in relation to eNB-Scheduling Resource Allocation (Mode 1) mode, D2D data transmission, ie, in particular T-RPT pattern / bitmap, starts in the next UL subframe after the last SA retransmission in the SA resource pool. As already explained for FIG. 6, The T-RPT Mode1 (Temporary Transmission Resource Pattern, T-RPT) bitmap mainly determines the transmission timing of the MAC PDU (1st transmission) and its retransmissions (2nd, 3rd, and 4th transmission).

The direct connection data transfer procedure can be found in the standard document 3GPP TS 36.321 v13.2.0, section 5.14, which is incorporated herein by reference. It details Autonomous Resource Selection Mode-2, which differs when configured with one radio resource pool or multiple radio resource pools.

What has been discussed above is the current state of the 3GPP standard for D2D communications. However, it should be noted that there is ongoing discussion on how to further improve and improve D2D communications, which will likely lead to some changes being introduced to D2D communications in future revisions. The present invention, as will be described later, will also be applicable to these later editions.

For example, in relation to 3GPP Rel. 14, which is currently under development, 3GPP may decide to change the transmission timing so that it is no longer based on SC periods as discussed above, but in a different way (for example, based on subframes just like / similar to Uu ). Accordingly, the above detailed examples of how transfers can be performed via the direct connection interface (PC5) are only exemplary and can be applied to Rel. 13, but possibly not for later revisions of the respective 3GPP standards.

In addition, in future revisions of the D2D infrastructure, in particular in connection with vehicle-related communications, the T-RPT may no longer be used.

ProSe Network Architecture and ProSe Objects

FIG. 8 illustrates a high-level exemplary architecture for a non-roaming case, including different ProSe applications in respective UEs A and B, as well as ProSe Application Server and ProSe function in the network. Exemplary Architecture FIG. 8 is taken from TS 23.303 v.13.2.0 chapter 4.2 Architectural Reference Model, which is incorporated herein by reference.

Functional entities are presented and explained in detail in TS 23.303 Subclause 4.4 Functional Entities, which is incorporated herein by reference. The ProSe function is a logic function that is used for the network-related actions required for ProSe and plays a different role for each of the ProSe features. The ProSe function is part of the 3GPP EPC and provides all relevant network services like authorization, authentication, data processing, etc. related to proximity services. For direct ProSe discovery and communication, the UE can receive UE ProSe specific identity, other configuration information, as well as authorization from the ProSe function via the PC3 reference point. There may be multiple ProSe features deployed on a network, although a single ProSe feature is presented for simplicity of illustration. The ProSe function consists of three main subfunctions that perform different roles depending on the ProSe attribute: Direct Submission Function (DPF), Direct Discovery Name Administration Function, and EPC Layer Discovery Function. DPF is used to provide the UE with the necessary parameters to use ProSe Direct Discovery and ProSe Direct Communication.

The term “UE” as used in this connection refers to a ProSe-enabled UE supporting ProSe functionality such as:

- Exchange of ProSe control information between ProSe-enabled UEs and ProSe Function through the PC3 reference point.

- Procedures for open Direct ProSe Discovery of other ProSe-enabled UEs via the PC5 reference point.

- Procedures for Direct One-to-Many ProSe Communication through the PC5 reference point.

- Procedures for acting as a UE-to-ProSe Network Relay. The remote UE communicates with the ProSe UE-to-Network Relay through the PC5 reference point. The ProSe UE-to-Network repeater uses layer-3 packet forwarding.

- Exchange of control information between ProSe UEs through the PC5 reference point, for example for UE-to-ProSe Network Relay detection and ProSe Direct Discovery.

- Exchange of ProSe management information between other ProSe-enabled UEs and the ProSe Function through the PC3 reference point. In the case of a UE-to-ProSe Repeater, the Remote UE will send this control information through the PC5 user plane to be relayed over the LTE-Uu interface to the ProSe Function.

- Parameter configuration (for example, including IP addresses, ProSe Layer-2 Group ID, Group security material, radio resource parameters). These parameters can be pre-configured in the UE, or, if in coverage, provided by signaling through the PC3 reference point to the ProSe Function in the network.

The ProSe Application Server supports the ProSe EPC User ID Store, and ProSe Function IDs, and the display of the Application Layer User ID and ProSe EPC User ID. The ProSe Application Server (AS) is an entity outside the scope of 3GPP. The ProSe application in the UE communicates with the ProSe AS through the application layer reference point PC1. AS ProSe connects to the 3GPP network through the PC2 reference point.

Vehicle-related communications - V2X services

A new research subject was formulated in 3GPP in Rel. 14 to consider the usefulness of new LTE features for the automotive industry - including Proximity Service (ProSe) and LTE-based broadcast services. The ProSe functionality explained above is thus seen as offering a good basis for V2X services. Changes to the D2D infrastructure are being discussed regarding how the transmission of vehicle-related communications can be improved. For example, T-RPT templates may no longer be used. In addition, frequency division multiplexing may be provided instead of or in addition to the use of TDD as previously discussed for data and SA transmission. Collaborative services in vehicle-related scenarios are becoming integral to the future connected vehicle within the ITS (Intelligent Transport Systems) research area. They are supposed to reduce road traffic fatalities, increase road capacity, reduce the carbon footprint of road transport, and improve the user experience while traveling.

V2X communication is the passage of information from a vehicle to any object that can affect the vehicle and vice versa. This exchange of information can be used to improve safety, mobility and environment applications to enable vehicle safety with driver assistance, speed adaptation and warning, emergency response, trip information, navigation, transportation, commercial fleet planning and payment transactions. ...

LTE support for V2X services contains 3 types of different use cases, which are as follows:

- V2V: covering LTE-based communication between vehicles.

- V2P: encompassing LTE-based communication between a vehicle and a device that is carried by an individual (for example, a portable terminal that is carried by a pedestrian, cyclist, driver and passenger).

- V2I: covering LTE-based communication between the vehicle and the roadside unit.

These three V2X types can leverage “shared awareness” to deliver smarter services to end users. This means that transport entities such as vehicles, roadside infrastructures, and pedestrians can collect knowledge about their local environment (for example, information received from other vehicles or sensor equipment in their immediate vicinity) in order to process and share these values. in order to provide more intelligent services such as joint collision warning or autonomous driving.

For V2V communications, E-UTRAN allows such UEs (vehicles) in close proximity to each other to exchange V2V-related information using E-UTRA (N) when the authorization, authorization and proximity criteria are met. Proximity criteria can be configured via MNO (Mobile Network Operator). However, UEs supporting the V2V Service may exchange such information when served or not served by an E-UTRAN that supports the V2X Service.

The device (vehicle UE) supporting V2V applications transmits application layer information (eg, its location, dynamics and attributes as part of the V2V Service). The V2V payload must be flexible to accommodate different content of information, and information can be transmitted periodically according to the configuration provided by the MNO.

V2V is predominantly broadcast-based; V2V involves the exchange of V2V-related application information between individual devices directly and / or, due to the limited direct communication range of V2V, the exchange of V2V-related application information between individual devices through an infrastructure supporting the V2X Service, for example RSU, an application server , etc.

For V2I communication, a V2I application capable device sends application layer information to the Roadside Unit, which in turn can send application layer information to a group of devices or a V2I application support device.

Also introduced is V2N (Vehicle with Network, eNB / CN), in which one side is the UE and the other side is the serving entity, both supporting V2N applications and communicating with each other via the LTE network.

For V2P communications, the E-UTRAN allows such UEs that are in close proximity to each other to exchange V2P related information using the E-UTRAN when the authorization, authorization and proximity criteria are met. Proximity criteria can be configured via MNO. However, the UE supporting the V2P Service can exchange such information even when the E-UTRAN that supports the V2X Service is not being served.

The UE supporting V2P applications transmits the application layer information. Such information may be broadcasted by a vehicle with a UE supporting the V2X Service (eg, pedestrian warning) and / or by a pedestrian with a UE supporting the V2X Service (eg, warning to a vehicle).

V2P involves the exchange of V2P-related application information between individual UEs (one for the vehicle and the other for the pedestrian) directly and / or, due to the limited direct communication range of V2P, the exchange of V2P-related application information between individual UEs via the infrastructure supporting V2X Service, such as RSU, application server, etc.

For this new V2X study subject, 3GPP has provided specific concepts and definitions in TR 21.905, current version 13.0.0, which can be reused for this application.

Roadside Unit (RSU): An entity supporting V2I Service that can transmit to and receive from a UE using a V2I application. The RSU can be implemented in an eNB or a fixed UE.

V2I Service: A type of V2X Service in which one side is a UE and the other side is an RSU, with both sides using a V2I application.

V2N Service: A type of V2X Service in which one side is the UE and the other side is the serving entity, with both parties using V2N applications and communicating with each other via LTE network entities.

V2P Service: A type of V2X Service in which both sides of the communication are UEs using a V2P application.

V2V Service: A type of V2X Service in which both sides of the communication are UEs using a V2V application.

V2X service: A type of communication service that includes a transmitting or receiving UE using a V2V application over 3GPP transport. On the basis of the other party involved in the link, it can be further divided into V2V Service, V2I Service, V2P Service, and V2N Service.

Many ITS services have general communication requirements:

- Periodic exchange of status. ITS services generally need to know about the status of the vehicle and roadside terminals. This implies the periodic exchange of data packets with information about location, speed, ID, etc.

- Asynchronous notifications. This type of message is used to inform about a special service event. In contrast to previous status messages, reliable delivery of these messages to a single terminal or group of terminals is usually a key requirement.

Examples of the use of the first type of communication can be found in traffic efficiency services, such as remote vehicle monitoring, which collects periodic status data from vehicles, or safety services, such as collaborative collision avoidance, which require kinematic information about surrounding vehicles. to detect potential collisions. Asynchronous notifications are mainly found in security services such as slippery sidewalk warnings or post-collision warning.

Different message types are already and will be defined for V2V communication. Two different message types have already been defined by ETSI for Intelligent Transport Systems, see the relevant European Standards ETSI EN 320 637-2 v1.3.1 and ETSI EN 302 637-3 v1.2.1:

- Collaborative Awareness Messages (CAM), which are continuously triggered by vehicle dynamics to reflect the status of the vehicle.

- Decentralized Environment Notification Messages (DENM), which are triggered only when vehicle-related security events occur.

As V2V and ITS standardizations are rather early, it is expected that other messages may be defined in the future.

Continuous (periodic) CAM broadcasts are carried out by ITS-Ss to exchange status information with other ITS-Ss and thus have a greater impact on traffic load than event-triggered (aperiodic) DENMs. Essentially, CAM messages are a kind of “live” messages that are periodically broadcast by each vehicle to its neighbors to provide presence, position, temperature and basic status information. In contrast, DENMs are event-triggered messages that are broadcast to notify road users of a hazardous event. For this reason, the traffic characteristics of CAM messages, as defined by the ETSI for the ITS, are considered more representative of V2V traffic.

Collaborative Awareness (CAM) messages are messages exchanged in the ITS network between ITS-S in order to create and maintain awareness of each other and to support vehicle interoperability using the road network. Point-to-multipoint communication must be used for the transmission of CAMs so that the CAMs are transmitted from the source ITS-S to the receiving ITS-S located in the forward range of the source ITS-S. The generation of the CAM must be initiated and administered through the basic Shared Awareness service, which defines the time interval between two consecutive CAM generation times. Currently, the upper and lower limits of the transmission interval are 100ms (i.e., the CAM generation frequency of 10Hz) and 1000ms (i.e., the CAM generation frequency of 1Hz). The underlying philosophy of the ETSI ITS is to send a CAM when there is new information to share (eg new position, new acceleration, or new heading values). Accordingly, when vehicles are moving slowly and at a constant course and speed, the high frequency of CAM generation does not provide real advantages, since the CAMs show only minimal differences. The CAM transmission frequency of a single vehicle varies between 1Hz and 10Hz as a function of vehicle dynamics (eg speed, acceleration and course). For example, the slower the transport neighborhood moves, the fewer CAMs are initiated and transmitted. Vehicle speed is the main influencing factor in CAM traffic generation,

In the above, periodic Joint Awareness messages have been described. It should be noted, however, that although some of the information above has already been standardized, other information such as message frequency and size is not yet standardized and based on assumptions. In addition, standardization may change in the future and thus, aspects of how CAMs are generated and transmitted may also change.

In order for the vehicle UE to have radio resources on a direct connection to transmit the CAM, Mode 1 and / or Mode 2 radio resource allocation is assumed, as explained above. For Mode 1 radio resource allocation, the eNB allocates resources for SA message and data for each SA period. However, when there is a lot of traffic (eg, high frequency periodic traffic), the Uu link overhead from the UE to the eNB can be large.

As evident from the above, most of the V2V traffic is periodic, so 3GPP agreed that for Mode 1 direct connect V2V (i.e. eNB planned radio resource allocation), semi-persistent direct connect radio resource allocation will be supported by eNB and UE.

It has been decided to support the sensing mechanism along with semi-persistent transmissions to facilitate the autonomous control / resource selection mechanism for direct V2X connectivity. The UE will indicate in the PSCCH (SA / SCI) that it has data on the selected set of recurring resources until a resource selection occurs. This resource reservation information (signaled in the SCI) can be used by other UEs that intend to transmit a V2X message to select a resource so that resources that are already reserved / reserved by other UEs are not considered for radio resource selection. This resource reservation / reservation procedure is particularly suitable for traffic for which packets arrive at regular intervals, such as CAM messages.

Monitoring ("sensing") the indication of the reserved radio resources in the scheduling information, as mentioned above, is performed by other (vehicle-related) devices. In general, the probing procedure gathers information on radio resources and thus provides a prediction of future radio resources that can be used in the resource allocation procedure to identify a set of potentially suitable resources (candidate resources) for transmission. Very few things have already been agreed by 3GPP, but it can be assumed that the sounding process classifies time-frequency resources into:

- 'Unavailable' resources. These are resources on which the UE is not allowed to transmit because these resources have already been booked / reserved by other UEs, and

- 'candidate resources (or available)'. These are the resources on which the UE can / will be able to transmit.

In addition, 3GPP agreed to also perform energy measurements for the sensing procedure, although the agreement does not provide any details as to how and what energy measurements should be performed. Thus, energy-based sensing can be understood as a process in which the UE measures the received signal strength over the PSCCH radio resources and / or the PSCCH radio resources. Energy-based sensing, as such, can be useful to identify sources of interference as near and far.

In addition, it was discussed whether the data priority (or the corresponding radio resource reservation) is indicated in the scheduling assignment (SCI) so that it can be used in the resource allocation procedure, although it was not agreed on how the priority is actually used.

An additional topic that arose during the discussion was the use of a channel congestion level (i.e., the PC5 interface) for the resource allocation procedure, which may be similar to the Channel Occupancy Ratio (CBR), which is already known from the ETSI standards (see, for example , ETSI EN 302 571 v 2.0.0 and 102 687 v1.1.1). Again, no details were discussed in this regard, let alone agreements on how exactly to use this level of overflow.

Probing should be implemented in a simple manner so as not to increase the complexity of the UE too much. It should also be noted that there may be several ways / options for how to implement the probing algorithm.

Although general agreements have been reached regarding sensing and resource reservation for V2X transmissions over the PC5 interface, implementing these mechanisms in current systems can lead to problems and inefficiencies.

SUMMARY OF THE INVENTION

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

In accordance with a first aspect, a transmitter is provided for determining radio resources for transmitting data (eg, vehicle-related periodic or non-periodic data) via a direct interface to other devices. It is assumed that the resource sensing procedure is continuously performed by the transmitter so as to obtain information about future radio resources. In accordance with one example, probing radio resources at least comprises monitoring scheduling assignments transmitted by other devices that advertise and / or reserve radio resources at a later time point (s). The reserved radio resources can then be excluded from the selection of radio resources. Probing may also comprise measuring the received signal energy in radio resources. In the future, other information may also be collected during the probing. However, it should be noted that the probing procedure is not performed in the subframes in which the device is transmitting, since the transmit and receive operations cannot be performed by the device at the same time.

It is assumed that at a specific time, data will become available for transmission and the device will proceed to perform the UE-autonomous resource allocation procedure so as to determine the relevant transmission parameters, including the actual time-frequency radio resources that should be used for data transmission. A transmission window may be defined, starting at the moment data becomes available, within which transmission (and possibly retransmissions) must be completed, for example, so as to meet delay requirements for data. Alternatively, the probing window can be defined as a period of time before data is available and during which the probing operation acquires information about the radio resources in the transmission window. During the procedure for probing radio resources, the vehicle-related UE autonomously determines transmission parameters and selects radio resources so as to perform data transmission within the transmission window.

Based on the results of the sounding procedure, the radio resource selection distinguishes between primary subframes and secondary subframes in the transmission window, with the secondary subframes being those subframes in the transmission window for which the resource sounding procedure provides less information than possible because in at least one subframe in the probing window that corresponds to the secondary subframe, the vehicle-related UE performs transmission and thus cannot perform the resource probing procedure. Conversely, primary subframes are those subframes in the transmission window for which the resource probing procedure performed by the vehicle UE gathers all possible information as it performs the resource probing procedure in all corresponding subframes of the probing window. For example, an unfulfilled resource probing procedure in subframe t of the probing window will result in a lack of information in future subframes that are at a distance of possible data transmission intervals. As an example, assuming a frequency of multiples of 100ms, with a minimum of 100ms and a maximum of 1000ms, the subframes t + 100ms, t + 200ms, t + 300ms, ... and t + 1000ms will be considered secondary subframes when in the transmission window of the UE vehicle.

The vehicle UE should select the preferred radio resources from the primary subframes over the radio resources from the secondary subframes. In this regard, given more than one possible radio candidate resource, the ranking of the radio candidate resources should be separate for primary subframes and secondary subframes, and the UE should select the highest ranked candidate to use for data transmission. Optionally, if the highest ranked candidate cannot be used (e.g., causing a conflict with other UEs), the highest ranked second candidate can be used, etc. The ranking procedure as such can be performed in different ways. It is advantageous to use the time delay between the radio candidate resource and the arrival time of the data, as well as the energy prediction obtained for the radio candidate resources during the probing procedure for ranking candidates. Radio candidate resources that result in a short time delay are preferred over those that result in longer delays. On the other hand, low energy prediction radio candidate resources are preferred over those for which the sounding procedure predicts high transmission energy.

While it is possible to use the measurement across all subframes of the sounding window for energy prediction, further options improve energy prediction for a particular radio candidate resource by considering only those subframes that relate to the subframe of the radio resource candidate, the ratio being based on possible data periods , i.e. -100ms, -200ms, -300ms,…, -1000ms, as discussed above.

In accordance with a further aspect, radio resource selection and transmission performed by a vehicle-related UE for scheduling assignments is improved in a manner similar to that performed for data transmissions. Accordingly, a radio resource reservation can be made for transmission of scheduling assignments, and a vehicle-related UE performs a radio resource probe procedure, the results of which can be used to select a radio resource for scheduling assignment transmissions. The resource reservation for scheduling assignments can be implemented separately or in conjunction with a radio resource reservation for data. When co-implemented with data resource reservation, the vehicle-related UE either reserves radio resources for both data and scheduling assignments, or not for one of them. An appropriate indication can be provided in the scheduling assignment such that the receiving entities are aware that the received scheduling assignment also reserves radio resources for one or more future transmissions of the scheduling assignment and / or data.

The radio resource selection procedure performed to transmit the scheduling assignment can also distinguish between primary and secondary subframes, as discussed above with respect to data transmissions. The corresponding results of the sounding procedure are used in this relation so as to distinguish subframes in the transmission window for which the resource sounding procedure receives all possible information (leading to primary subframes) or does not receive all possible information (resulting in a secondary subframe). An un-probed subframe t in the probing window results in a secondary subframe t + 100ms, t + 200ms, t + 300ms,…, t + 1000ms. Again, resources from the primary subframes must be selected in preference over resources in the secondary subframes to perform a selection procedure for transmitting a scheduling assignment. The procedure for ranking candidates in primary subframes and in secondary subframes must be performed separately from each other. The actual procedure for ranking candidate resources for transmission of a scheduling assignment can be performed in exactly the same manner as discussed above for ranking a candidate resource for data transmissions. For example, radio candidate resources that result in a short time delay are preferred over those that result in longer delays. On the other hand, low energy prediction radio candidate resources are preferred over those for which the sounding procedure predicts high transmission energy.

Accordingly, in one general first aspect, the techniques disclosed herein characterize a transmitter for determining radio resources to be used to transmit data from a transmitter over a direct interface to one or more receiving devices. The receiver and processor of the transmitter perform a resource sensing procedure so as to obtain information about radio resources that can be used for the transmitter to transmit data at a later point in time. After the data becomes available for transmission, the processor performs an autonomous radio resource allocation to select radio resources in the transmit window to be used for transmitting data based on information obtained through the resource probe procedure during the probing window before the data became available for transmission. Autonomous allocation of radio resources comprises selecting radio resources in primary subframes of a transmission window, preferably over radio resources in secondary subframes of a transmission window. Secondary subframes in the transmission window correspond to those subframes in the sounding window during which the transmitter did not perform the resource sounding procedure, and the primary subframes in the transmission window correspond to those subframes in the sounding window during which the transmitter performed the resource sounding procedure.

Accordingly, in one general first aspect, the techniques disclosed herein describe a method for a transmitter to determine radio resources to be used to transmit data from a transmitter over a direct interface to one or more receiving devices. The method comprises the step of performing a resource sensing procedure by the transmitting device so as to obtain information about radio resources that can be used for the transmitter to transmit data at a later point in time. After the data becomes available for transmission, the transmitter performs an autonomous radio resource allocation to select radio resources in the transmit window to be used for data transmission based on information obtained through the resource probe procedure during the probing window before the data became available for transmission. Autonomous allocation of radio resources comprises selecting radio resources in primary subframes of a transmission window, preferably over radio resources in secondary subframes of a transmission window. Secondary subframes in the transmission window correspond to those subframes in the sounding window during which the transmitter did not perform the resource sounding procedure, and the primary subframes in the transmission window correspond to those subframes in the sounding window during which the transmitter performed the resource sounding procedure.

Accordingly, in one general first aspect, the techniques disclosed herein characterize a transmitter for transmitting scheduling assignments and data over a direct connect interface to one or more receiving devices. The receiver and processor of the transmitter perform a resource sensing procedure to obtain information about radio resources that can be used by the transmitter to transmit scheduling assignments at a later point in time. After the first data becomes available for transmission, the processor performs an autonomous radio resource allocation procedure to select radio resources in the transmission window for transmitting the first data, and to select radio resources in the transmission window for transmitting the first scheduling assignment based on the information obtained by procedures for probing resources during the probing window before the first data became available for transmission. The first scheduling destination contains information on the selected radio resources in the transmission window for transmitting the first data. The transmitter of the transmitter transmits the first scheduling assignment using the selected radio resources and transmits the first data using the selected radio resources. The first scheduling assignment further indicates reserved radio resources that can be used at a later point in time by the transmitter to transmit the second scheduling assignment for the second data.

Accordingly, in one general first aspect, the techniques disclosed herein describe a method for a transmitter for transmitting scheduling assignments and data over a direct interface to one or more receiving devices. The method comprises the step of performing a resource sensing procedure to obtain information on radio resources that can be used by the transmitter to transmit scheduling assignments at a later point in time. After the first data becomes available for transmission, the method comprises performing an autonomous radio resource allocation procedure to select radio resources in the transmission window for transmitting the first data, and select radio resources in the transmission window for transmitting the first scheduling assignment based on information obtained through the resource probing procedure during the probing window before the first data became available for transmission. The first scheduling destination contains information on the selected radio resources in the transmission window for transmitting the first data. The method then comprises transmitting a first scheduling assignment using the selected radio resources and transmitting the first data using the selected radio resources. The first scheduling assignment further indicates reserved radio resources that can be used at a later point in time by the transmitter to transmit the second scheduling assignment for the second data.

Additional beneficial results and advantages of the disclosed embodiments will be apparent from the technical description and the Figures. Beneficial results and / or advantages may be individually provided by various embodiments and features of the technical description and drawings of the invention, and it is not required that all be provided in order to obtain one or more of the same.

These general and specific aspects can be implemented using a system, method, and computer program, and any combination of systems, methods, and computer programs.

BRIEF DESCRIPTION OF THE FIGURES

In the following, exemplary embodiments are described in more detail with reference to the accompanying figures and drawings.

FIG. 1 shows an exemplary architecture of a 3GPP LTE system,

FIG. 2 shows an example downlink resource grid of a downlink slot at a subframe as defined for 3GPP LTE (Revision 8/9).

FIG. 3 schematically illustrates how a layer-2 link is created through PC5 for ProSe communication,

FIG. 4 illustrates transmission / reception resource utilization for overlay (LTE) and substrate (D2D) systems,

FIG. 5 illustrates the transmission of Scheduling Assignment and D2D data for two UEs,

FIG. 6 illustrates D2D communication timing for UE-Autonomous Scheduling Mode 2,

FIG. 7 illustrates the D2D communication timing for Mode 1 eNB scheduling,

FIG. 8 illustrates an exemplary architecture model for ProSe for a no-roaming scenario,

FIG. 9 illustrates the radio time-frequency resources of a data resource pool for a vehicle-related UE at time P when data becomes available for transmission in a transmission window and a sounding window,

FIG. 10 illustrates radio time frequency resources of a data resource pool for a vehicle-related UE in accordance with an exemplary implementation of the first embodiment, where transmission window subframes are classified as primary or secondary subframes depending on the sounding procedure,

FIG. 11 is a timeline for UE behavior in accordance with an exemplary implementation of the first embodiment,

FIG. 12 illustrates radio time-frequency resources of a data resource pool for a vehicle-related UE in accordance with an exemplary implementation of the first embodiment, further illustrating an improved energy sensing procedure in a sounding window for candidate radio resources in a transmission window,

FIG. 13 is a flowchart for UE behavior in accordance with an exemplary implementation of the first embodiment, further illustrating a preemption procedure to be performed if no resources are found in primary and secondary subframes,

FIG. 14 is a flow chart of the displacement procedure illustrated in FIG. thirteen,

FIG. 15 is a timeline for UE behavior in accordance with an exemplary implementation of the first embodiment, further illustrating a channel occupancy reset function,

FIG. 16 is a flowchart for UE behavior in accordance with an exemplary implementation of the first embodiment, further illustrating a collision function for detecting possible SA collisions and data transmission,

FIG. 17 is a timeline for UE behavior in accordance with an exemplary implementation of the second embodiment, and

FIG. 18 illustrates radio time frequency resources of a scheduling assignment resource pool for a vehicle-related UE in accordance with an exemplary implementation of the second embodiment, where transmission subframes are classified into primary or secondary subframes depending on a sounding procedure.

DETAILED DESCRIPTION

A mobile station or mobile node or user terminal or user equipment is a physical entity in a communication network. One node can have several functional objects. A functional object refers to a software or hardware module that implements and / or offers a predetermined set of functions to other functional objects of a node or network. Nodes can have one or more interfaces that attach the node to a communication facility or medium through which the nodes can communicate. Similarly, a network entity may have a logical interface that attaches a functional entity to a communication facility or medium through which it can communicate with other functional entities or related nodes.

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

The term "direct transmission" as used in the patent application should be understood broadly as transmission directly between two user equipments, ie, not via a radio base station (eg, eNB). Accordingly, the transfer of a direct connection is performed through a "direct connection of a direct connection", which is the concept used for a connection created directly between two user equipments. For example, 3GPP uses the terminology for D2D (Device-to-Device) communication or ProSe communication or direct connect communication. The term “direct connection direct connection”, “direct connection interface” should be understood in a broad sense and in the context of 3GPP can be understood as the PC5 interface described in the prior art section.

The term "ProSe" or in its non-abbreviated form, "Proximity Services" as used in the patent application is used in the context of proximity-based applications and services in the LTE system, as explained by way of example in the related art section. Other terminology such as "D2D" is also used in this context to refer to Device-to-Device communication for Proximity Services.

The term “vehicle-related mobile terminal” as used throughout the patent application is to be understood in the context of the new 3GPP research subject, respectively working question V2X (vehicle-related), as explained in the related art section. Accordingly, a vehicle-related mobile terminal is to be understood broadly as a mobile terminal, which is particularly installed in a vehicle (e.g., a passenger car, commercial trucks, motorcycles, etc.) in order to carry out vehicle-related communication, those. ensuring the passage of information related to the vehicle to other objects (such as vehicles, infrastructure, pedestrians), for example, for safety purposes or to assist the driver. Optionally, the vehicle-related mobile terminal can access information available in the navigation system (provided that it is also installed in the vehicle), such as map information, etc.

The term “autonomous radio resource allocation” (inversely “base station-controlled radio resource allocation”) as used throughout the patent application can be taken as an example in the context of 3GPP Proximity Services allowing two modes for resource allocation; namely, Mode 1 (i.e., radio base station-controlled allocation of radio resources) in accordance with which the radio base station controls the allocation, and Mode 2 (i.e., autonomous allocation of radio resources) in accordance with which the terminal (or transmitting device) autonomously selects resources (no radio base station).

As explained in the related art section, 3GPP is introducing a new research subject for LTE-enabled vehicle communications that should be based on ProSe procedures to exchange V2X traffic between various vehicle-related mobile terminals and other stations. In addition, the kind of semi-persistent radio resource allocation should be supported for V2X traffic, and it was agreed that mechanisms for radio resource reservation, as well as sounding, would be supported for this purpose - in particular for UE-autonomous resource allocation mode (also referred to as Mode 2). However, only general agreements have been reached with respect to sensing and radio resource reservations, without providing details on how to implement them and how to adapt other mechanisms to ensure efficient and flawless operation.

For example, it remains unclear how exactly the resource sensing mechanism should be implemented. In particular, it is unclear how the energy measurement is calculated and how resources should be selected based on the sensing mechanism during Mode 2 radio resource allocation.

One possible solution will be explained in the following with reference to FIG. 9, which illustrates the time-frequency resources of a data resource pool of a vehicle-related UE (transmitter as a whole). A PRB pair (a pair of Physical Resource Blocks; 12 subcarriers for one subframe) is taken as a unit for exemplary illustration of radio time-frequency resources in the figure. FIG. 9 is an exemplary and simplified illustration to explain the solution. It is assumed that at time P, data will become available for transmission (i.e., a packet arrives), and data transmission (possibly, however, also retransmissions) should be completed at time L, which is denoted as a transmission window and depends from the delay requirement (s) of the data to be transmitted (for example, 100ms; L = P + 100ms). The results of the sounding procedure, obtained within the sounding window in the form of, for example, 1000ms before the packet arrives, should be taken into account for the radio resource allocation procedure to be performed by the vehicle UE in order to select the time-frequency radio resources (and possibly other transfer parameters) for data transfer. As an example, it is assumed that three pairs of (physical) resource blocks are required for data transmission (according to the current standardization, the resource blocks should be contiguous).

One of the information obtained from the sensing procedure is that specific radio resources in the transmission window are already reserved by other devices and thus should not be used by the vehicle UE; the corresponding cells have vertical shading. The remaining candidate radio resources (three adjacent resource block pairs) in the full transmission window that are available to the vehicle UE for data transmission are illustrated as boxed in FIG. 9. There are six candidates in total in the transmit window, all of which can be ranked based on the energy measurements taken during the sounding process in the sounding window.

In more detail, it is possible to measure energy (eg, received signal strength) across the entire sensing window for associated radio candidate resources. By way of example, it is assumed that the respective radio candidate resources are ranged from 1 to 4, as illustrated in FIG. 9 based on energy measurements. Accordingly, candidate radio resources 2 having the same radio frequency resources in the sounding window are equally ranked. The same applies to the radio candidate resources 3 at the bottom of the figure. FIG. 9 illustrates, with diagonal shading, the respective radio resources of the sounding window over which the measured energy is averaged to predict the energy for the candidate radio resources 2. Similarly, FIG. 9 indicates the corresponding radio time-frequency resources in the sounding window used to measure energy for candidate resource 4, horizontally shaded. Although not illustrated in FIG. 9 for simplicity of illustration, corresponding energy and processing measurements are also performed for radio resources in the probing window corresponding to candidates 1 and 3. Accordingly, the vehicle-related UE can then select the highest ranked radio candidate resource (candidate 1 in this example) for use for data transmission, for example, the lowest energy prediction candidate.

The above provides a possible solution to implement the sensing procedure and the corresponding allocation of radio resources.

Its optional implementation therefore deals with a situation where there are no available candidate radio resources (for example, when too many radio resources are reserved by other devices). A related UE in this way may need to select a candidate radio resource that conflicts with radio resources that have already been reserved by other devices; this procedure can be referred to as "displacement". During the preemption procedure, the vehicle UE may select suitable radio resources from among the reserved radio resources in the transmission window randomly, or may select suitable reserved radio resources with relatively low received signal strength prediction. Alternatively, provided that the priority is also indicated for the reserved radio resources, the vehicle-related UE may select the reserved radio resources with the lowest priority.

However, several problems arise with the above solution. For example, predicting the received signal strength (transmission energy) for a particular radio resource candidate is based on received signal strength measurements made in the respective radio frequency resources over the entire sounding window, and if so, does not reflect the actual transmission situation in one subframe in which the resource candidate is located. Averaging the energy measurements over the entire sensing window for the radio candidate resource (s) in one particular subframe does not account for the fact that data transmissions and scheduling assignments typically occur periodically, i. E. only in special subframes. Moreover, the selection of radio resources, as exemplified above in connection with FIG. 9, gives transmission possibilities which are quite late, i.e. at the end of the transmission window, so that the vehicle UE, as well as the receiving entities, must wait for data for a long time; data waiting time increases. By using priority during the preemption procedure, as discussed above, there is a possibility that the UE that is being preempted (i.e., the UE whose resources conflict with the selected radio candidate resource) is located close to the related UE so that there is strong interference between two "conflicting" transmissions.

As explained in the prior art section, D2D transmissions over a direct connection interface do not use full duplex, but half duplex, so that simultaneous V2X transmission and reception is not possible. Therefore, in those subframes where the vehicle UE performs transmission (eg, scheduling and / or data assignments), the sensing procedure cannot be performed by the vehicle UE. It is unclear how these missed probing opportunities will affect the resource allocation procedure performed by the vehicle UE.

The following exemplary embodiments are conceived by the inventors to mitigate the problem (s) explained above.

Specific implementations of the various embodiments are to be implemented in a broad whitepaper as defined by the 3GPP standards and explained in part in the prior art section, with specific key features added as explained in the following embodiments. It should be noted that the embodiments can be advantageously used, for example, in a mobile communication system such as 3GPP LTE-A communication systems (Revision 10/11/12/13/14 or later) as described in the Technical Background Art section. but the embodiments are not limited to their use in these specific exemplary communication networks.

The explanations are not to be understood as limiting the scope of the invention, but as only exemplary embodiments in order to better understand the present invention. A person skilled in the art should be aware that the general principles of the present invention, as set forth in the claims, may be applied to various scenarios and in ways that are not explicitly described herein. A number of assumptions are made for purposes of illustration, which, however, should not limit the scope of the following embodiments.

Various embodiments mainly provide a radio resource allocation procedure performed by a vehicle UE when transmitting data to one or more receiving devices. Other functionality (i.e., functionality that does not vary by different embodiments) may remain exactly the same as explained in the prior art section, and may be changed without affecting different embodiments. This may include, for example, other procedures such as how the subsequent data transmission is accurately performed by the vehicle UE, or how different transmitters detect each other.

One exemplary scenario to which the various embodiments may be applied is V2X communication, as exemplified in the related art section. Therefore, the transmitting and receiving devices can be, for example, a UE in a vehicle, a roadside unit, a "normal" mobile terminal that is carried by a pedestrian, and so on. In addition, the data may be (periodic) vehicle-related data, eg, CAM messages, which must be continuously exchanged between various vehicle-related entities, and for which the resource sensing procedure and semi-persistent resources have been discussed in 3GPP.

Although the following exemplary embodiments will be explained for purposes of illustration in connection with such a V2X communication scenario, the invention should not be limited thereto.

First embodiment

In the following, a first embodiment to solve the above problem will be described in detail. Different implementations and variations of the first embodiment will also be explained.

As mentioned above, it is assumed as an example a vehicle-related UE that is installed in a vehicle and is capable of performing vehicle-related communications based on a D2D infrastructure as explained in the prior art section of this patent application. Accordingly, vehicle related data (eg, periodic and nonperiodic data) must be transmitted to vehicle UEs to other entities that are interested in the data.

The UE is assumed to support and mainly execute Mode-2 radio resource allocation and has been correctly configured by the necessary resource pool (s) to be able to autonomously select radio resources for transmitting scheduling information as well as data via the PC5 interface (direct connection ).

The periodic data to be transmitted to the vehicle UE will be exemplified by Collaborative Awareness Messages (CAMs), which are explained in detail in the related art section. As explained in the prior art section, sensing and radio resource reservations have been generally agreed by 3GPP for inclusion in future edition (s) of the standard in connection with periodic data transmission. In particular, reserving radio resources on the transmitting side enables the implementation of a kind of "semi-persistent" radio resource allocation by, for example, reserving the same resources as currently used also for one or more time instances to transmit further periodic data packets. Therefore, the vehicle UE does not need to perform resource selection / request (Mode-1 or Mode-2 resource allocation) again at those later time instances in order to be able to transmit periodic data. The radio resource reservation can be implemented in various ways and is not yet committed by 3GPP. For example, radio resource reservations can be made for the next transmission instance or for a longer period of time (i.e., more than just the next periodic data transmission instance). Scheduling information (SCI), carried with the direct connection data, identifies the radio resources that are used for transmission, and thus allows the receiving entity to correctly receive and process / decode the direct connection data. The scheduling information can further be used to indicate radio resource reservations, for example, by specifying a time or data periodicity so that the receiving entity can determine for what time (eg, subframe) radio resources are reserved.

The vehicle UE must further continuously perform the radio sensing procedure, as explained in the prior art, so as to obtain information about future radio resources. This information can then be used during the Mode-2 radio resource allocation procedure performed by the vehicle UE to select radio resources (and possibly other transmission parameters) for data transmission (as well as the corresponding scheduling assignment, however). The sensing procedure includes decoding scheduling assignments transmitted by other devices so as to identify the reserved radio resources. Optionally, the sensing procedure further comprises energy measurements (eg, received signal strength, RSSI) across all frequency resources for data transmissions configured for the vehicle UE.

One potential option for implementing a resource sensing procedure is that each UE has a frequency resource prediction map that spans, for example, 100ms (with, for example, a maximum of 1 second) starting from the next subframe. Then, at time P, when the packet arrives at the buffer in the UE, the UE already has a prepared map of all frequency resources for subframes from P to L (can be called a transmission window), where L mainly corresponds to the maximum time interval (according to QoS ) during which the packet must be transmitted. The frequency map can distinguish between unavailable and available radio resources (and possibly also contain information about the predicted energy level of different radio resources). Other implementations of the radio sounding procedure are equally possible, for example, where the UE does not continuously update such a future resource map, but instead predicts radio resources from the last measurements in the sounding window only when needed.

In summary, it is assumed that the vehicle-related UE continuously performs the radio resource probing procedure to obtain information about future radio resources (whether it be reservations and / or RSSI predictions or other information as well). The vehicle-related UE must additionally be able to transmit periodic (and non-periodic) data and must, in said communication, perform a Mode-2 (UE-autonomous) resource allocation procedure so as to select radio resources in the transmission window to be used for transmission data (may additionally include determining other transmission parameters such as MCS, for example). Based on transmission parameters (such as modulation scheme, coding rate, etc.), the vehicle-related UE determines the number of resource blocks required for transmission, and subsequently identifies possible radio resources for data transmission, thus using the determined number of resource blocks. ... As an example, it is assumed that only contiguous resource blocks should be used prior to transferring a direct connection.

The first embodiment provides an improved radio resource allocation procedure, taking into account the results obtained from the sounding procedure performed before. According to the first embodiment, the radio resources in the transmission window (i.e., those radio resources from which the UE can select suitable radio resources for transmission) are differentiated into radio resources of the primary subframes and the radio resources of the secondary subframes. The secondary subframe of the transmission window should correspond to the subframes in the sounding window where the vehicle-related UE does not perform the resource sounding procedure and thus obtains less information through the sounding. In contrast, the subframes of the transmission window are primary subframes when they correspond to subframes in the sounding window where the vehicle UE performed the sounding procedure. The prediction for the secondary sub-frame should thus be considered less accurate than for the primary sub-frames, and thus radio resources from the secondary sub-frames are less preferred for selection during the resource allocation procedure. In more detail, since simultaneous transmission and reception are not supported by the vehicle-related UE over a direct connection interface (see the prior art section), when the vehicle-related UE transmits in a subframe, it cannot simultaneously perform reception operations, and thus cannot perform resource probe procedure. The resource probe procedure collects information on future radio resources for use during the radio resource allocation procedure. As currently agreed, the sensing procedure at least includes monitoring radio resource reservations and possibly performing energy measurements. In future revisions of 3GPP, other types of information may be obtained during the sounding procedure, and the embodiments presented herein may still be applied.

As an example, it is assumed that the vehicle UE is transmitting in subframe t and thus cannot perform the probing procedure in that subframe. A vehicle-related UE can thus potentially skip a scheduling assignment procedure (with or without reservation) and / or transmit data by one or more other transmitters.

As currently standardized, periodic vehicle-related data (such as CAM messages) are transmitted in multiples of 100ms (e.g. 200ms, 300ms, 400ms, ...; where the maximum frequency between two CAMs is 1s and the minimum frequency is 100ms) ... Different or additional periodicities may be defined in the future and should also be encompassed by the options for implementation presented in this document. Radio resource reservations are typically performed for periodic data, and as such, are based on the above mentioned possible periodic data intervals.

In a subframe where the probing procedure has not been performed, a possible missed scheduling assignment could only reserve radio resources at some predetermined time distances, depending on the periodicities discussed above that are possible for periodic data. For simplicity, it is assumed that the scheduling assignment primarily indicates radio resources for data transmission in the same subframe as the scheduling assignment, such that a skipped radio resource reservation in subframe t has potentially reserved radio resources in a subframe that is spaced apart by the appropriate data frequency, for example , t + 100ms, t + 200ms, t + 300ms,…, t + 1000ms. For this reason, a vehicle-related UE, transmitting in subframe t and thus not performing the probing procedure in subframe t, will count all associated subframes t + 100ms, t + 200ms, t + 300ms, ..., t + 1000ms as secondary subframes during a possible radio resource allocation procedure (being within the transmission window).

Likewise, a missed data or SA transmission in sub-frame t cannot be probed by the vehicle UE through the received signal strength measurement. Again, given that periodic data transmissions can only occur at fixed time distances (e.g. 100ms or 200ms or 300ms or ... or 1000ms), the vehicle-related UE considers that the energy predictions for subframes t + 100ms and t + 200ms and t + 300ms and ... t + 1000ms are not accurate due to the lack of measurement information for subframe t.

Thus, a non-probed subframe results in a lack of prediction information for the subsequent subframe (s), which are thus considered, according to the first embodiment, as secondary subframes as opposed to primary subframes for which the probing procedure has received all possible information (e.g., resources are reserved or not radio, and energy measurements for all radio frequency resources on that subframe).

The vehicle UE must then select, within the transmit window, preferably radio resources from the primary subframes over radio resources from the secondary subframes. In other words, when determining radio resources for data transmission, only if radio resources are not available from the primary subframes, the vehicle-related UE has to select radio resources from the secondary subframes.

In general, the selection of radio resources is based on previous definitions of transmission parameters such as modulation scheme and coding rate to be used for data transmission. The vehicle UE thus determines the number of resource blocks that will be needed for transmission. In accordance with current agreements and discussions in 3GPP, it is assumed that contiguous resource blocks should be used for direct connection transmissions. In the following exemplary illustrations, it is assumed that three contiguous resource blocks are required for data transmission. The thus obtained candidate resources are respectively illustrated in the following figures, for example see FIG. ten.

In connection with this procedure, it is also advantageous to rank the radio candidate resources of the primary subframes separately from the radio candidate resources of the secondary subframes. Accordingly, during the Mode-2 resource allocation procedure, the vehicle-related UE, after determining the plurality of radio candidate resources in the primary subframes, will proceed to ranking them in order to be able to select the optimal candidate for data transmission. The possible candidate radio resources in the secondary subframes will be ranked separately from them, i. E. ranging is performed only within the radio candidate resources of the second subframes. During the radio resource allocation procedure, the vehicle-related UE will then select the candidate with the highest rank from the primary subframes, and if not available, will select the candidate with the highest rank from the secondary subframes.

FIG. 10 is a diagram of time-frequency resources of a data resource pool, and illustrates the result of a procedure for sensing and allocating radio resources in accordance with one exemplary implementation of the first embodiment as an example. FIG. 10 discloses radio time-frequency resources that are generally available to a vehicle UE to perform data transmissions over a direct-connect interface, eg, suitable radio resources from a data radio resource pool as described in the prior art section. Accordingly, the probing procedure (performed in the probing window) is also performed on these radio resources, for example, radio resources of a data transmission resource pool. For ease of illustration, the relevant sounding window energy measurements for radio candidate resources in the transmit window, as illustrated in FIG. 9 are omitted from FIG. 10. As is evident from this, the transmission of the UE in subframe t, as well as the resulting secondary subframe m, in t + 600ms, is illustrated. In the exemplary illustration of FIG. 10, it is assumed that a missed probing opportunity in subframe t results in only one secondary subframe m within a transmission window; for example, since the transmission window is only 100ms, depending on the transmission window length, a UE transmission in subframe t may result in more than one secondary subframe (i.e., t + 600ms and t + 700ms, t + 800ms, ...) ... A separate ranking procedure within the radio candidate resources of the primary subframes as well as within the radio candidate resources of the secondary subframes is also apparent from FIG. ten; secondary radio candidate resources are enclosed in a dotted line box. Specifically, there are four candidate radio resources from the primary subframe (ranked 1 to 4), and there will be two candidate radio resources from the secondary subframes (ranked 1 to 2) in the case where the primary candidate radio resources are not available.

A simplified and exemplary sequence diagram illustrating the behavior of a vehicle-related UE in accordance with one exemplary implementation of the first embodiment is shown in FIG. 11. The various steps to be performed by the vehicle UE, as generally explained above, are depicted in FIG. 11. The procedure for probing resources is depicted separately from this to indicate that the probing of resources should be performed continuously. The dashed lines from the resource sounding procedure to the steps of searching and ranking a radio resource candidate for primary and secondary subframes are to be understood as input of information (eg, radio resource reservation, and radio resource energy measurement).

There are several options for how to perform the radio candidate resource ranking procedure. One possible, albeit disadvantageous, solution is presented in connection with FIG. 9 above. Alternatively, the ranking of the candidates may be based only on the time delay between the candidate radio resource and the arrival time of the packet; that is, disregarding energy measurements / predictions for ranking so that candidates resulting from only a short delay are preferred over candidates that result in a long delay. Other particularly advantageous ranking procedures will be described in the following as variants of the first embodiment. The ranging procedure can be based on the energy measurements taken during the sensing window, as well as the temporal distance of the candidate radio resource from the point in time when the data becomes available for transmission. By further considering the delay that may result from using a candidate for data transmission, latency for data transmissions should be reduced. At the same time, the likelihood that a resource will be occupied by a radio candidate resource can also be accounted for by considering past RSSI measurements.

Two characteristics, energy prediction and latency, considered for ranking, can be considered differently. In particular, the delay between the radio candidate resource and the packet arrival time can be considered first, and in the case where more than one radio candidate resource with the same time delay is present, prediction of the received signal strength can be used to rank candidates with one and the same delay; candidate resources are ranked, for example, from high to low in the order of increasing RSSI, so that the candidate with the lowest energy prediction is the candidate with the highest rank for that subframe. Conversely, prediction of received signal strength can be considered first, and then in the case where more than one radio candidate resource with the same received signal strength prediction is present, a time delay can be used for ranking, where the shorter time delay is ranked higher. than a longer time delay. In accordance with a further alternative, the delay and prediction function of the received signal strength may be used to rank candidate radio resources. An example function would be Z _i = X * T _i + Y * RSSI _i . X and Y are weights respectively given for the time delay and received signal strength characteristics. T _i denotes the temporal distance between the candidate radio resource i and the arrival time of the packet. RSSI _i denotes a prediction for received signal strength at candidate radio resource i (based on previous measurements during the sounding window). The smaller the value of Z _i , the higher the ranking for candidate resource i. The weights X and Y can be configured by the eNB, for example, or otherwise predefined.

The result of an exemplary ranging procedure that primarily deals with time lag as described above is illustrated in FIG. 10. As apparent from this, the highest ranked primary radio candidate resource (ranking value 1) is the radio candidate resource in the primary subframe that has the lowest delay with respect to the packet arrival time. The remaining candidate radio resources in the primary subframes are also ranked based on their temporal distance from the time of packet arrival. On the other hand, the ranking procedure for the secondary sub-frame m must additionally rely on energy measurements taken during the sensing window to distinguish between the two radio candidate resources; an exemplary ranking is illustrated in FIG. ten.

A further advantageous embodiment of the first embodiment improves the prediction of received energy levels for a candidate radio resource. As explained in connection with FIG. 9, one possible option is to use energy measurements in radio resources that correspond to the radio resources of a particular radio resource candidate across the entire probing window to predict the received signal strength of a particular radio resource candidate. The disadvantage of this, however, is that it may not reflect the actual transmission situation in a given one subframe of the candidate radio resource. In order to improve the prediction of transmit energy, only associated subframes should be considered for prediction. In more detail, the associated subframes in the sounding window are those that have the temporal distance of the possible data periodicity with respect to the radio candidate resources to be ranked. As currently assumed for data transfers, the data rate is a multiple of 100ms (with a minimum of 100ms and a maximum of 1000ms). Therefore, for improved energy prediction for a particular subframe m in the transmit window, the associated subframes in the probing window are m-100ms, m-200ms, m-300ms, m-400ms, ... and m-1000ms. Energy measurements made only in these associated subframes of the sounding window are used to predict the energy in subframe m of the transmission window.

FIG. 12 illustrates by way of example this improved transmission energy prediction based on assumptions already made for FIG. 10 and distinguishes between six radio candidate resources that are defined for the primary and secondary subframes. As is evident from this, FIG. 12 illustrates, for a primary radio candidate resource 1 in subframe u, energy measurements in respective radio resources of subframes u-600ms and u-1000ms. Energy measurements in the remaining associated subframes of the probing window, i.e. u-100ms, u-200ms,…, u-500ms, u-700ms, u-800ms, u-900ms are also taken into account even though they are not shown in Fig. 12 for ease of illustration. Likewise, both radio candidate resources of the secondary subframe m are associated with subframes m-100ms, m-200ms, ..., m-1000ms in the sounding window, even though energy measurements in different radio resources are used for the associated subframes. Accordingly, FIG. 12 marks associated radio resources in subframes m-1000ms used for energy prediction. It should be noted that energy measurements in the radio resources of the subframe m-600ms were not possible due to the transmission being performed by the vehicle UE. As discussed previously, possible 600ms periodic transmissions affecting subframe m of the transmission window will thus not be probed, which is one reason for classifying subframe m as only secondary in relation to the radio resource allocation procedure. The strength (i.e., energy) of the received signal, measured in radio resources on associated subframes, can then, for example, be averaged to obtain a prediction of a candidate radio resource in a subframe of a transmission window.

The advantage is that improved energy prediction is more accurate because it takes into account the periodicity of data transmissions.

Other advantageous implementations of the first embodiment provide solutions for cases where no suitable radio resources are found in either primary or secondary subframes. As previously discussed, the preemption procedure allows radio resources to be selected from among the radio resources in the transmit window even when they are already reserved by other transmitting devices.

FIG. 13 is an example timeline for UE behavior based on the diagram of FIG. 11 and extended by the preemption procedure as a step in the case where the vehicle UE is unable to find resources in the secondary subframes (after also failing to find resources in the primary subframes). As evident from FIG. 13, after determining the radio resources during the preemptive procedure, the vehicle-related UE proceeds to determine the corresponding radio resources for the scheduling assignment and then transmits both the SA and the data. In addition, the propelling unit receives information from the resource sensing procedure as input, such as energy measurements on radio resources, reservations of radio resources made by other devices, and possibly also information on the priority of reserving radio resources. The latter information requires that priority information (such as PPPP, Priority-of-Per-Packet-ProSe) be transmitted along with the radio resource reservation and thus also be decoded and stored by the vehicle UE during the sounding procedure.

FIG. 14 is a simplified and exemplary flow chart for a preemption procedure that may be performed on a vehicle UE in the event that no radio resources are available and should be considered as one possible implementation of the preemption procedure illustrated in FIG. 13. An optional check to be performed at the beginning of the eviction procedure is whether or not the data to be transmitted (ie, ignored so as not to be transmitted) can be discarded. In one exemplary implementation, the vehicle-related UE determines whether or not data should be discarded based on the priority of the data, which can be compared with a suitable priority threshold. Data is usually associated with a Settlement-per-ProSe-Priority (PPPP), which indicates the priority of the data. A suitable priority threshold may be determined in a vehicle-related UE, for example by an eNodeB, and used to distinguish between data that can be cleared and that cannot be cleared. If the priority is not high enough (for example, below the priority threshold), the data is discarded; otherwise, the preemption proceeds to select the radio resources to be used for data transmission, however, this time considering the reserved radio resources that were originally excluded from the previous candidate search in the primary and secondary subframes. As mentioned above, the data flush is an optional check that is performed by the vehicle UE, and if so, it can be configurable, for example, by the eNB or overlay on the vehicle UE.

Although illustrated as part of the flush check, the flush check can also be performed outside of the actual flush check, so that the flush (without flush check) is performed only when the packet is not flushed.

Moreover, the decision on whether to flush or not to flush data can be made by the upper layer of the vehicle related UE (such as RRC or application layer).

Crowding refers to the process of selecting and using radio resources that are already reserved by other transmitting devices in order to transmit data. Some of the reserved radio resources are thus "overwritten" by their own transmission, which can cause serious interference and should therefore be avoided as much as possible. Yet, when the data is important enough, the vehicle UE must determine one or more candidate radio resources with a suitable resource block size that - in part or in whole - contains the reserved radio resources. If there are more than one available candidate resources, the vehicle UE needs to determine the most suitable candidate. One possible option is to perform a random selection of candidates over the entire transmission window, or preferably in primary subframes and then in secondary subframes, as previously discussed.

In accordance with preferred implementations of the first embodiment, the selection of the radio candidate resource during the preemption procedure is improved to mitigate any preemption problems by considering the radio resource priority and / or the RSSI prediction determined during the sounding procedure in the sounding window. In one example, the vehicle-related UE performs preemptive behavior by selecting the lowest priority radio candidate resource from the reserved radio resources. Then, if multiple candidates with the same priority remain, the vehicle-related UE may select the candidate with the lowest RSSI prediction. In a second example, the vehicle UE selects the radio candidate resource with the lowest RSSI prediction level, and in the case of several remaining candidates, the radio resource candidate with the lowest priority is selected for data transmission. Alternatively, the function can be determined based on two parameters, reservation priority and RSSI, weighted individually. An example function would be Z _i = w1 * 1 / P _i + w2 * RSSI _i . w1 and w2 are weights according to given priority (lowest priority value is highest priority) and received signal strength characteristics. P _i denotes the priority given to the particular radio resource reservation as part of the candidate resource i, and RSSI _i denotes the prediction of the received signal strength of the candidate resource i. The vehicle UE should select the radio candidate resource with the smallest (smallest) value of Z _i .

Optionally, the reservation priority can be compared with the data priority so that only reserved radio resources with a priority lower than the data to be transmitted should be preempted. As another option, it may be possible to determine the appropriate priority and energy thresholds so as to be able to limit the selection of radio resources to only "optimal" resources that lie below both thresholds; radio resources above the thresholds are filtered out. As an optional addition, the eviction procedure can also distinguish between primary and secondary subframes, and then should preferably select a candidate from the primary subframe over a candidate in the secondary subframe.

In addition or alternatively, the preemption procedure should preferably determine a candidate radio resource for data transmission that covers the smallest amount of reserved radio resources. In particular, since only a set of contiguous resource blocks can be used to transfer data over a sidelink, preempting only a small number of reserved resource blocks may be sufficient to obtain a sufficiently large set of resource blocks to transfer data. Thus, interference with other transmitting UEs is reduced.

As an additional possible criterion for a preemption procedure, the reserved radio resources can be chosen to minimize the number of other devices that will be affected by the crowding out, or to maximize the number of other devices so that each device is less affected by the crowding out while still having the ability to decode data.

In the case where multiple candidates remain after considering two or three parameters (reservation priority, data priority, or RSSI) according to any of the examples above, the vehicle UE may randomly select one of the remaining radio candidate resources.

By taking into account the energy predictions for the preemptive procedure, strong interference with the data transmission performed by the vehicle UE with the captured data transmission from the nearby vehicle UE should be prevented.

After determining the appropriate radio resources for data transmission in this manner, the vehicle-related UE proceeds as illustrated in FIG. 13 to the selection of resources for transmitting the scheduling assignment, and then transmits both the scheduling assignment and data, however.

In accordance with a further advantageous implementation of the first embodiment, the congestion level of the direct connection channel is taken into account for the radio resource allocation procedure performed by the vehicle UE. The congestion rate of the forward link channel (also referred to as the channel occupancy rate, CBR) is determined by the vehicle UE, for example, by comparing the energy level of sufficient samples to a threshold across the entire bandwidth or only within one resource pool. For example, if 90% of the samples have an energy level above the threshold, the CBR is 90%. The threshold value can be fixed or configurable by the eNB, or pre-configured. CBR measures the occupancy rate of a carrier or resource pool. CBR can be used by the vehicle UE to determine whether or not to discard data due to channel status. In general, this CBR check is optional and can be configured, for example, by the eNodeB or pre-configured (eg, by an operator), thereby configuring the UE as to whether and how the CBR check should be performed. For example, if the eNodeB is conservative and wishes to protect the direct connect carrier, it may thus configure some or all of the UEs in its cell (eg, by broadcasting system information) to perform such a CBR check. On the other hand, if the eNodeB is interested in achieving higher throughput, it can configure the UEs not to perform this CBR check. One possible implementation of the CBR check takes the priority of the data to be transmitted and compares it to a priority threshold, which can optionally be dependent on the CBR that is detected for the direct connection. For example, only if the priority of the data to be transmitted is high enough, the procedure will continue despite the high level of channel congestion. On the other hand, low priority data may be discarded due to a busy channel.

The type of data traffic to be transmitted can also be accounted for in the CBR flush function, either in addition to or as an alternative to data priority. For example, different thresholds can be defined for security traffic and non-security traffic. Assuming a priority level of 1 to 5, where the higher the number, the lower the priority. For a CBR of 90%, security traffic with priority level 5 and non-security traffic with priority levels 5, 4, and 3 should be dropped. On the other hand, if the CBR is 80%, security traffic will never be dropped, whereas only non-security traffic with priority level 5 should be dropped. If the CBR is 70%, security traffic will never be dropped, whereas non-safety traffic with priority level 5 or 4 should be dropped, and so on.

If the data is discarded, the responsible upper layer is informed about the failure of the data transmission, for example in such a way that the upper layer can decide to send the data again later, or discard the data also on the upper layer and inform the user of the failed transmission.

FIG. 15 is an exemplary sequence diagram based on the diagram of FIG. 11, and extended CBR validation as discussed above. In particular, after the data becomes available for transmission, the vehicle-related UE may decide whether or not to discard the data based on the channel occupancy ratio. The procedure, as known from FIG. 11 and described in detail above, then continues if the vehicle-related UE decides not to discard data.

The CBR check can either be considered part of the resource allocation procedure or a step prior to resource allocation so as to determine whether resource allocation should begin at all.

Moreover, the radio resource sensing procedure can be performed based on the radio resource pool configured in the vehicle UE for resource allocation Mode-2. In this case, whether and how the vehicle-related UE should use the CBR check can be configured per resource pool. For example, during the configuration of the data resource pool (s), the eNodeB may indicate whether and how CBR checks should be performed. For out-of-coverage UEs and their respective radio resource pools, the CBR configuration may be part of the pre-configuration for each resource pool.

In accordance with further advantageous implementations of the first embodiment, collision tests are provided to determine whether a scheduled transmission of a scheduling assignment, respectively, collides with another UE's data transmission. FIG. 16 is an exemplary sequence diagram based on the diagram of FIG. 11, and an extended one implementation of collision checking, as discussed in the following. As evident from FIG. 16, after selecting suitable resources for transmission of scheduling assignments and data, the vehicle-related UE continues to perform the probing procedure and thus monitors scheduling assignments transmitted by other UEs, possibly making future resource reservations. Based on the received scheduling assignments from other UEs, the vehicle-related UE can thus check whether the scheduled transmission of the scheduling assignment conflicts with the announced transmission of the other UE, as indicated by the monitored scheduling assignment. In the event of a conflict, the vehicle-related UE may decide how to proceed further and may, for example, compare the priorities of the two conflicting transmissions; ie, own transmission of the SA and transmission of the other UE. In the case where the own SA transmission has a higher priority, the vehicle-related UE continues with the transmission of the scheduling assignment as already scheduled. Alternatively, the vehicle-related UE may return to the first step (s) of the radio resource allocation procedure to determine new radio resources for scheduling assignments, and optionally also for data transmission. Alternatively, SA and data are discarded in case of conflict; especially when the priority of the own transmission of the SA is lower.

Conflict detection functions in a similar way for data transmission. It is assumed that the scheduling destination for data transmission has been transmitted. The sensing procedure is continuously performed by the vehicle UE during the data transmission time, and thus possible data transmissions by other devices conflicting with their own data transmission can be detected. In such a case of conflict, the vehicle-related UE may, for example, compare the priorities of the two data transmissions. In the case where the native data transmission has a higher priority, the vehicle-related UE continues with the data transmission as previously scheduled. In another case, the vehicle UE may need to return to the first steps of the radio resource allocation procedure to determine new radio resources for data and SA transmission. Alternatively, the data is discarded in the event of a conflict; especially when the priority of own transmission is lower.

In the above, different implementations of the first embodiment have been described, where a “basic” implementation is described in connection with FIG. 11, and extensions for said "base" implementation are described respectively in FIG. 13, 14, 15, and 16. Although the extensions are described and illustrated separately, some or all of them may be combined to form the overall behavior of the UE, which then contains the eviction procedure in FIG. 13 and / or the CBR reset function in FIG. 15 and / or checking the conflict in FIG. sixteen.

In the above, it is assumed that the vehicle UE always uses the results of the probe procedure for the UE-Autonomous Resource Allocation (Mode 2). However, whether and how probing is used for resource allocation may instead be configured and / or dependent on the 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 probing procedure should affect the radio resource allocation. For example, the eNodeB may broadcast the corresponding configuration in its cell so that all vehicle UEs in the cell receiving the configuration know whether and how to use probing for UE-autonomous resource allocation. Alternatively, the dedicated message is transmitted from the radio base station to only one or more vehicle-related UEs so as to control whether and how the sensing procedure should be implemented in those vehicle-related UEs.

Second embodiment

In the following, a second embodiment will be described, which can be used in combination with various implementations of the first embodiment. In connection with the first embodiment, it was simply assumed that the vehicle UE selects resources for transmitting the scheduling assignment without going into details as to how the vehicle UE actually performs resource selection. As explained in the prior art section, the selection of resources for transmitting the scheduling assignment is well defined in previous editions of 3GPP. Briefly, in relation to UE-Autonomous Radio Resource Allocation (Mode 2), the vehicle-related UE may randomly select radio resources from the corresponding scheduling assignment resource pool, and may further select a T-RPT template to repeat this scheduling assignment. However, while 3GPP discussed and agreed on the implementation of improvements for the selection of resources for data transmission (a mechanism for reserving radio resources was introduced, as, indeed, the sensing procedure, as discussed above), nothing was discussed or agreed on how the transmission of the scheduling assignment could be improved for future revisions. One motive for consistent improvements with respect to V2X data transmissions is to increase the reliability of such transmissions, which cannot be guaranteed by a purely arbitrary choice of radio resources for data transmission (eg, based on contention frequency). For example, the number of vehicle UEs is expected to grow in the future, and the random resource selection mechanism for transmitting scheduling assignments may lead to an increased number of collision failures. However, reliable transmission of the scheduling destination, in particular in a vehicle-related environment, is just as important as the reliability of the data transmission.

The second embodiment thus provides an improved UE-autonomous radio resource allocation procedure for selecting radio resources for transmitting a scheduling assignment. The transmission of scheduling assignments is improved to reproduce the improvements provided for data transmissions as discussed for the first embodiment. Accordingly, implementations of the second embodiment provide a resource sensing procedure that is performed by the vehicle UE for radio resources of one or more SA resource pools that can be used by the transmitter to transmit scheduling assignments. It should be noted that the resource probing procedure, as described in the first embodiment, probes possibly different radio resources, namely those from the pool of data resources that can be used by the transmitter for data transmission. The radio resources of the scheduling assignment resource pool and the radio resources of the data resource pool may, however, overlap. In any case, in a manner similar to that described in detail in the first embodiment, a vehicle-related UE must obtain information on future radio resources of a scheduling assignment by continuously executing a sensing procedure on those radio resources.

As will be described in more detail in the following implementation of the second embodiment, radio resource reservation must also be implemented for transmission of scheduling assignments, not only for data transmission as described in the first embodiment. Reservation of radio resources for scheduling and data assignments can be similar. Briefly, by providing suitable indications in the scheduling assignment, radio resources used to transmit the current scheduling assignment can be reserved for one or more future transmissions of the scheduling assignment.

By monitoring scheduling assignments transmitted by other devices, the resource sensing procedure should thus also allow the vehicle UE to obtain information as to whether and which radio resources are reserved by other transmitters for transmitting scheduling assignments. These reserved radio resources can then be excluded from the radio resource allocation procedure that is performed on the vehicle UE to select radio resources for transmitting the scheduling assignment. The radio sensing routine can also comprise energy measurements (eg, received signal strength, RSSI) over frequency resources configured to transmit scheduling assignments. Other types of information may also be collected in the future. The sensing procedure thus collects information on future radio resources to be used for transmitting scheduling assignments that can be used during the resource allocation procedure to select optimal radio resources for transmitting scheduling assignments.

It is assumed that the vehicle-related UE should transmit periodic data and perform the UE-autonomous radio resource allocation procedure so as to determine resources for transmitting scheduling assignment and pending data.

As discussed in detail in connection with the first embodiment, the radio resource allocation procedure can be improved by discriminating between the radio resources of the primary subframes and the radio resources of the secondary subframes, taking into account the results obtained from the sounding procedure. The secondary subframe of the transmit window should correspond to the subframes in the sounding window where the vehicle-related UE does not always perform the resource sounding procedure and thus obtains less information through the sounding, compared to the primary subframes that correspond to the subframes in the sounding window where the related the vehicle, the UE always performs the probing procedure and thus obtains all possible information. The vehicle-related UE may thus skip a reservation for transmitting a scheduling assignment by another UE in the secondary subframe, or skip an energy measurement affecting energy prediction for the secondary subframe, as explained in detail for the first embodiment.

Thus, prediction for secondary subframes is less accurate than for primary subframes, and radio resources from secondary subframes should thus be selected less favorably than radio resources from primary subframes.

As a result, this improvement in the resource allocation procedure as detailed for the first embodiment in connection with the selection of radio resources for data transmission can be applied in accordance with the second embodiment to select radio resources for transmission of scheduling assignments.

FIG. 17 is a sequence diagram similar to FIG. 11 of the first embodiment illustrating an exemplary and simplified behavior of a UE in accordance with an implementation of the second embodiment. As is evident from this, the selection of radio resources for transmission of the scheduling assignment is divided into a search in primary subframes and a subsequent search in secondary subframes. In particular, after data becomes available for transmission, the vehicle-related UE must select, within the transmission window, radio resources for SA transmission, preferably from primary subframes, and in the absence of radio resources for transmission of SAs available in primary subframes, the vehicle UE must search for radio resources for SA transmission in secondary subframes. The procedure then continues with transmission of the scheduling assignment and subsequent transmission of pending data.

FIG. 18 illustrates radio time-frequency resources for a pool of scheduling assignment resources, with resources available to a vehicle UE to transmit scheduling assignments. In a manner similar to that of FIG. 10, Fig. 18 illustrates how primary and secondary subframes are determined within a transmit window as a result of an outstanding probe procedure in one subframe of the probing window. Also, for transmission of a scheduling assignment, the vehicle-related UE must first determine the appropriate parameters and thus the number of resource blocks that will be required to transmit the SA. As agreed at the moment, two pairs of physical resource blocks should be used to transmit the scheduling assignment. The vehicle UE then determines the candidate radio resources that will be available for transmission of the scheduling assignment, where an exemplary candidate search result is illustrated in FIG. eighteen.

The radio candidate resources of the primary subframes should be ranked separately from the radio candidate resources from the secondary subframes, for example, in exactly the same or similar manner as discussed for the first embodiment. This is also illustrated in FIG. 18, which shows four primary SA candidate radio resources and separately two secondary SA candidate radio resources. In particular, various different implementations of the ranking procedure, as discussed for data transmission in accordance with the first embodiment, can also be reused to rank radio candidate resources that can be used to transmit scheduling assignments. For example, ranking is possible, as discussed in connection with FIG. 9 despite the flaws. Alternatively, the candidate ranking may be based only on the time delay between the radio candidate resource and the packet arrival time, in particular considering that the scheduling assignment is required to be transmitted before (or in the same subframe) data transmission. Another option for ranking candidates considers both time delay and energy prediction for a candidate radio resource based on energy measurements taken during the sounding procedure; various different implementations are presented above in connection with the first embodiment, and may be reused here for implementations of the second embodiment.

In particular, advantageous implementations of the first embodiment improve energy prediction as explained in connection with FIG. 12. These improved energy measurements and predictions can also be applied to a resource sensing procedure performed by a vehicle UE over radio resources to transmit scheduling assignments. Accordingly, the energy prediction for a specific candidate resource in subframe m should take into account measurements in the sounding window of only subframes that are associated with the subframe of the candidate resource, i.e., located at a distance of possible periodicities, m-100ms, m-200ms, m- 300ms,…, m-1000ms.

As illustrated in FIG. 17, a preemptive procedure may be provided during the resource allocation procedure for cases where suitable radio resources cannot be found in 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 scheduling assignments can be acquired by a vehicle-related UE so as to still be able to transmit scheduling assignments. In addition, the preemption procedure can comprise determining whether the scheduling assignment should be reset, the determination can be based on the priority of the data for which the scheduling assignment will be transmitted, which can be compared with a suitable priority threshold. If the data, and thus the scheduling assignment, has sufficient priority, the vehicle-related UE may proceed to determine candidate resources for transmitting the scheduling assignment, this time also considering the reserved radio resources. Various advantageous implementations of the preemption procedure have been discussed in detail in connection with the first embodiment and are believed to also be reused to improve the selection of radio candidate resources for transmitting scheduling assignments. For example, the priority of the reserved radio resources and / or the RSSI prediction that is determined during the sounding procedure in the sounding window can be taken into account. Moreover, the priority of the reserved radio resources can be compared with the priority of the data to be transmitted. Also, the preemptive procedure can distinguish between primary and secondary subframes and must select radio candidate resources predominantly from primary subframes.

In summary, the vehicle-related UE thus selects the optimal radio resources for transmitting the scheduling assignment. As discussed above, the vehicle UE must also reserve radio resources for the next transmission of scheduling assignments.

In some implementations of the second embodiment, it may be configurable whether or not the vehicle-related UE should apply semi-persistent scheduling (eg, radio resource reservation and sounding procedure) to the transmission of scheduling assignments. In accordance with one exemplary implementation, an eNodeB managing a vehicle-related UE may decide whether some or all of the UEs in its cell should improve the transmission of a scheduling assignment by further reserving radio resources for future scheduling assignment transmissions and performing resource selections. radio communications based on the results of the sounding procedure in the radio resources of the corresponding SA resource pool. The eNodeB can then inform the vehicle-related UE accordingly. For example, in a case where all UEs in a cell of an eNodeB are to be configured in the same way, the eNodeB may broadcast a system information message in its cell so that all UEs receiving said broadcast message configure an SA transmission procedure as prescribed.

On the other hand, how to transmit the scheduling assignments may be related to the transmission procedure followed by the vehicle UE when transmitting data. Therefore, if the vehicle-related UE applies semi-persistent scheduling for data transmissions, it should also apply semi-persistent scheduling for the corresponding SA transmissions; and similar for the sounding procedure. When the UE is not to use semi-persistent scheduling, the transmission of the scheduling assignment can be handled in a manner similar to that described in the prior art, for example, by randomly selecting radio resources from a suitable radio resource pool SA without any reference to the results of the sounding procedure.

Alternatively, or in addition to broadcasting a broadcast message in its cell, the eNodeB can transmit the dedicated value to the selected vehicle UEs, and thus these UEs will configure themselves according to the dedicated message instruction. Thus, the eNodeB can selectively configure vehicle-related UEs to perform semi-persistent scheduling for transmission of scheduling assignments.

The configuration of whether and how to transmit a scheduling assignment can also depend on a particular resource pool SA so that semi-persistent scheduling, as indeed the probe procedure, is performed when selecting radio resources for transmitting scheduling assignments from a particular configured resource pool (s). radio communications. Appropriate guidance when configuring radio resource pools at the beginning may be sufficient, for example, one bit for data and one bit for SA transmissions.

As will be described in the following, the second embodiment provides several implementations of how devices receiving a scheduling assignment infer whether or not a received scheduling assignment reserves radio resources for transmission of one or more future scheduling assignments. One option is to provide an appropriate field (e.g., one bit) in the scheduling assignment, with one bit value indicating that the scheduling assignment also reserves radio resources (e.g., those radio resources used to transmit the current scheduling assignment) also to transmit one or more future scheduling appointments. Conversely, a different bit value on the scheduling assignment field is understood by the receiving entities to indicate that no radio resource reservation is made for transmitting the scheduling assignment. Alternatively, instead of providing a separate field for reserving radio resources for scheduling assignments, other implementations of the second embodiment rely on implicit indication, for example using a corresponding scheduling assignment field to indicate whether or not radio resources are reserved for data transmissions. Therefore, the scheduling assignment indicates that, provided that data resources are reserved, the corresponding scheduling assignment resources should also be reserved. For example, the scheduling assignment may include a "periodicity" field, possibly indicating the frequency of the radio resource reservation, the number of instances of the reservation, and so on. The absence of radio redundancy (for data transmission, as well as for SA transmission), for example, is indicated by including the value 0 in this periodicity field.

In the above implementations of the second embodiment, retransmissions to be performed for scheduling assignments have not yet been considered. Yet, in order to increase the reliability of the transmission of the scheduling assignment, one or more retransmissions of the scheduling assignment must be performed by the vehicle UE via the direct connection interface. In said connection, in one exemplary implementation, a fixed number of (retransmissions) transmissions may be pre-configured. As in the prior art, a vehicle-related UE can transmit retransmissions of a scheduling assignment with a fixed timing with respect to the first transmission of a scheduling assignment. Alternatively, a different association between the first transmission and retransmissions of the scheduling assignment may be negotiated between the vehicle UE and the candidate receiving entities. In accordance with still other alternatives, the vehicle-related UE may also select radio resources to retransmit the scheduling assignment in an arbitrary manner, as is done for the first transmission. For example, radio resources available for transmission of scheduling assignments can be further divided into resources for the first transmission and resources for additional retransmissions of the scheduling assignment.

However, arbitrary selection of radio resources also for assignment retransmissions can be problematic. Specifically, scheduling assignments are transmitted using specific radio resources within the radio resource set, and potential receiving entities discover the scheduling assignments by blind decoding within the radio resource set (also referred to as a radio resource search space). In the prior art procedure, retransmissions of a scheduling assignment are performed with a fixed time dependence with respect to the first transmission of a scheduling assignment so that the receiving entity knows which (retransmissions) of one particular scheduling assignment belong to each other (e.g., to perform soft combining appropriately to successfully decode scheduling assignment). However, by implementing arbitrary resource selection also for retransmissions of scheduling assignments, such a fixed time dependence can no longer be guaranteed.

Therefore, a new mechanism needs to be provided to allow receiving entities to associate all transmissions and retransmissions for one specific scheduling destination. In accordance with one exemplary implementation of the second embodiment, a common identifier may be included in scheduling assignment transmissions so as to associate them together. Accordingly, a receiving device that receives different transmissions for one particular scheduling destination can then, based on the common identifier, associate the correct transmissions of the scheduling destination. According to one example, the common identifier may be a source identifier identifying both the vehicle-related UE being the transmission source and / or the current application generating data for which the scheduling destination is transmitted. The common identifier can be made part of the scheduling assignment, or can be encoded into part of the layer 1 identifier or CRC.

Additional implementations of the second embodiment improve the selection of radio resources for retransmissions of the scheduling assignment based on the results of the sounding procedure (eg, in the same manner as for the first transmission of the scheduling assignment discussed above). As discussed for the above random selection of radio resources for SA transmission, while improving the selection of radio resources based on the sounding results, a fixed timing relationship between the first transmission and retransmissions can no longer be guaranteed. Therefore, a new mechanism needs to be provided to allow receiving entities to associate all transmissions and retransmissions for one specific scheduling destination. In accordance with one exemplary implementation of the second embodiment, a common identifier, as already explained above, may be included in the scheduling assignment transmissions so as to associate them together. In accordance with one example, the common identifier may be a source identifier identifying both the vehicle-related UE being the transmission source and / or the current application generating data for which the scheduling destination is transmitted. The common identifier can be made part of the scheduling assignment, or can be encoded into the layer 1 identifier part.

Hardware and Software Implementation of the Present Invention

Other exemplary embodiments relate to implementing the various embodiments described above using hardware, software, or software in conjunction with hardware. In this regard, a user terminal (mobile terminal) is provided. The user terminal is configured to perform the methods described herein, including appropriate entities for proper participation in the methods, such as receiver, transmitter, processors.

In addition, it will be appreciated that various embodiments may be implemented or performed using computing devices (processors). The computing device or processor may, for example, be general purpose processors, digital signal processors (DSPs), problem-oriented integrated circuits (ASICs), field programmable gate arrays (FPGAs), or other programmable logic devices, etc. Various embodiments can also be made or implemented by combining these devices. In particular, 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 individually formed as chips, or a single chip can be formed to include some or all of the functional blocks. They can include the input and output of data associated with them. LSI may be referred to as IS, system LSI, super LSI, or ultra LSI in this document depending on the difference in integration. However, the technique for implementing an integrated circuit is not limited to LSI and can be implemented using a dedicated circuit or a general purpose processor. In addition, an FPGA (Programmable Gate Array) can be used, which can be programmed after the manufacture of the LSI, or a configurable processor in which the connections and cell settings located inside the LSI can be reconfigured.

In addition, various embodiments can also be implemented by software modules that are executed by a processor or directly in hardware. A combination of software modules and hardware implementation is also possible. The software modules can be stored on any kind of computer readable storage media such as RAM, EPROM, EEPROM, flash memory, registers, hard disks, CD-ROMs, DVDs, etc. In addition, it should be noted that individual features of different embodiments may be individually or in an arbitrary combination be the subject of another embodiment.

One skilled in the art will appreciate that numerous variations and / or modifications may be made to the present invention as shown in specific embodiments. Consequently, the present embodiments are to be considered in all respects as illustrative and not restrictive.

Provision 1. Transmitting device for determining the radio resources to be used to transmit data from the transmitting device via the direct interface to one or more receiving devices, the transmitting device contains:

the receiver and processor, which, during operation, perform a resource sensing procedure so as to obtain information about radio resources that can be used for the transmitter to transmit data at a later point in time,

after the data becomes available for transmission, the processor, during operation, performs an autonomous radio resource allocation to select radio resources in the transmission window to be used for data transmission, based on information obtained through the resource probing procedure during the probing window before the data is available for transmission, and

wherein the autonomous radio resource allocation comprises selecting radio resources in the primary subframes of the transmission window, preferably over the radio resources in the secondary subframes of the transmission window, and

the secondary subframes in the transmission window correspond to those subframes in the sounding window during which the transmitter did not perform the resource sounding procedure, and the primary subframes in the transmission window correspond to those subframes in the sounding window during which the transmitter performed the resource sounding procedure.

Statement 2. A transmitting device according to Statement 1, in which the resource sensing procedure contains:

- in order to determine radio resources that are reserved by other transmitting devices, the receiver and the processor, during operation, monitor scheduling information that is transmitted by other transmitting devices, indicating radio resources reserved by other transmitting devices for a later point in time,

- measure the energy of the received signal in the radio resources so as to identify the radio resources that are used by other transmitting devices for transmission.

Position 3. The transmitter according to Position 1 or 2, in which the processor, during operation, determines the secondary subframes as those subframes of the transmission window for which the resource sounding procedure has not received all possible information during the sounding window,

optionally, the missing information for the secondary subframe contains:

- possible reservation of radio resources by other transmitting devices made during a subframe in the sounding window in which the transmitter did not perform the resource sounding procedure, optionally, the definition of secondary subframes is based on possible frequency of radio resource reservations that can be made by other transmitters, and / or

- information on the energy of the received signal in the radio resources of the subframe in the sounding window, in which the transmitter did not perform the resource sounding procedure.

Position 4. A transmitter according to one of Positions 1 to 3, wherein the autonomous radio resource allocation further comprises determining one or more primary transmit radio candidate resources in primary subframes and optionally determining one or more secondary transmit radio candidate resources in secondary subframes ,

and in the case where more than one primary transmit radio candidate resources are present, the processor, during operation, performs ranking of the primary transmit radio candidate resource candidates, and in the case where more than one secondary transmit radio candidate resources are present, the processor, during operation, performs ranking of candidates of secondary transmit radio candidate resources, wherein the candidate ranking of one or more primary transmit radio candidate resources is separate from the ranking of candidates of one or more secondary transmit radio candidate resources,

optionally, in this case, the ranking of candidates considers the temporal distance of the candidate radio resource from the moment in time when the data became available for transmission, as well as the prediction of the energy of the received signal obtained by means of the procedure for probing resources for the radio resources to be ranked,

optionally in this case, the prediction of the received signal energy for the radio resources to be ranked is based on measurements of the received signal energy of the corresponding radio resources in all subframes of the sounding window or based on measurements of the received signal energy of the corresponding radio resources in the subframes of the sounding window associated with the subframe, radio resources which are to be ranked, optionally where the associated subframes are those subframes of the sounding window that have a distance from the radio resources to be ranked, a multiple of the possible transmission intervals by other transmitting devices,

optionally, the candidate ranking first considers the temporal distance and then the received signal energy, or the candidate ranking first considers the received signal energy and then the temporal distance, or the candidate ranking is based on a function of the temporal distance and the received signal energy.

Position 5. The transmitter according to one of Positions 1 to 4, wherein the transmitter does not perform the resource sounding procedure in that subframe when performing data transmission or transmission of a scheduling assignment for data transmission in a subframe.

Provision 6. A transmitting device according to one of Provisions 1 to 5, in which in the case when the radio resources cannot be selected to be used for data transmission, the processor, during operation, determines to reset the data in the case when the priority of the data available for transmission is below the preemptive priority threshold, and in the case where data is not flushed, the processor, during operation, performs a resource preemption procedure to select radio resources to be used for data transmission from among radio resources reserved by one or more other transmitting devices,

optionally, the processor, when executing the resource preemption procedure, selects the radio resources to be used for data transmission based on the priority of the reserved radio resources and / or the priority of the data to be transmitted and / or the energy of the received signal, measured by procedures for sounding resources in the radio resources of the corresponding subframes in the sounding window, optionally, while the selection of radio resources in the resource preemptive procedure either first considers the priority and then the energy of the received signal from the reserved radio resources, or first considers the energy of the received signal and then the priority of the reserved radio resources or based on the priority and received signal energy function of the reserved radio resources.

Position 7. A transmitter according to one of Positions 1 to 6, in which the receiver and the processor, during operation, determine the channel occupancy rate of the direct interface, indicating the level of overflow of the direct interface, and the processor, during operation, performs the procedure discarding data before performing autonomous radio resource allocation based on the determined channel occupancy ratio of the direct connect interface so as to determine whether data that becomes available for transmission should be discarded or not, and in the case where the processor determines not to discard data, the processor performs autonomous allocation of radio resources,

Optionally, during the data reset procedure, the processor resets the data when it determines that the priority of the data that becomes available for transmission is below the channel priority threshold, and the channel priority threshold depends on the specified channel occupancy ratio of the direct connection interface,

optionally, the transmitting device is configured by the radio base station controlling the transmitting device to perform or not to perform the data reset procedure, optionally, the configuration of the data reset procedure is separate for each of the plurality of resource pools used by the transmitting device to select radio resources for data transmission,

optionally in this case, the channel priority threshold is additionally dependent on the type of data that is made available for transmission, optionally the safety data-related channel priority threshold being below the non-safety-related channel priority threshold.

Statement 8. A transmission device according to one of Provisions 1 to 7, wherein the autonomous allocation of radio resources comprises excluding radio resources reserved by other transmitting devices from a plurality of transmission radio resources, and / or

wherein the radio candidate resource in the subframe comprises one or more resource blocks that are contiguous in the frequency domain.

Provision 9. A transmitter according to one of Provisions 1 to 8, wherein the probing window considered for autonomous allocation of radio resources contains time-frequency radio resources starting at a predetermined point in time before the data becomes available for transmission, and ending at the point in time when the data becomes available for transmission, and

the transmit window contains the radio time-frequency resources, starting in the initial subframe, which is immediately after the subframe in which the data became available for transmission, and ending in a subframe, which is at a predetermined distance from the initial subframe, with the distance depending on the delay requirements data that becomes available for transmission to be performed by the transmitting device.

Statement 10. A method for a transmitting device for determining radio resources to be used to transmit data from a transmitting device via a direct connection interface to one or more receiving devices, the method comprising the following steps performed by the transmitting device, in which:

performing a resource sensing procedure so as to obtain information about radio resources that can be used for the transmitter to transmit data at a later point in time,

after the data becomes available for transmission, autonomous radio resource allocation is performed to select radio resources in the transmission window to be used for data transmission based on information obtained through the resource probe procedure during the probing window before the data becomes available for transmission,

wherein the autonomous radio resource allocation comprises selecting radio resources in the primary subframes of the transmission window, preferably over the radio resources in the secondary subframes of the transmission window, and

the secondary subframes in the transmission window correspond to those subframes in the sounding window during which the transmitter did not perform the resource sounding procedure, and the primary subframes in the transmission window correspond to those subframes in the sounding window during which the transmitter performed the resource sounding procedure.

Statement 11. A method according to Statement 10, in which the resource sensing procedure comprises:

- monitoring scheduling information that is transmitted by other transmitting devices indicating radio resources reserved by other transmitting devices for a later point in time so as to determine radio resources that are reserved by other transmitting devices,

- measuring the energy of the received signal in the radio resources so as to identify the radio resources that are used by other transmitting devices for transmission.

Position 12. The method according to Position 10 or 11, wherein the method further comprising the step of determining the secondary subframes as those subframes of the transmission window for which the resource sounding procedure has not received all possible information during the sounding window,

optionally, the missing information for the secondary subframe contains:

- possible reservation of radio resources by other transmitting devices made during a subframe in the sounding window in which the transmitter did not perform the resource sounding procedure, optionally, the definition of secondary subframes is based on possible frequency of radio resource reservations that can be made by other transmitters, and / or

- information on the energy of the received signal in the radio resources of the subframe in the sounding window, in which the transmitter did not perform the resource sounding procedure.

13. A method according to one of Provisions 10 to 12, wherein the autonomous radio resource allocation further comprises determining one or more primary transmit radio candidate resources in primary subframes and optionally determining one or more secondary transmit radio candidate resources in secondary subframes,

and in a case where more than one primary transmission radio candidate resources are present, the method comprises ranking the candidates of the primary transmission radio candidate resources, and in the case where more than one secondary transmission radio candidate resources are present, the method comprises a step of performing a ranking of the candidates of the secondary transmit radio candidate resources, wherein the ranking of the candidates of one or more primary transmit radio candidate resources is separate from the ranking of the candidates of the one or more secondary transmit radio candidate resources,

optionally, in this case, the ranking of candidates considers the temporal distance of the candidate radio resource from the moment in time when the data became available for transmission, as well as the prediction of the energy of the received signal obtained by means of the procedure for probing resources for the radio resources to be ranked,

optionally in this case, the prediction of the received signal energy for the radio resources to be ranked is based on measurements of the received signal energy of the corresponding radio resources in all subframes of the sounding window or based on measurements of the received signal energy of the corresponding radio resources in the subframes of the sounding window associated with the subframe, radio resources which are to be ranked, optionally where the associated subframes are those subframes of the sounding window that have a distance from the radio resources to be ranked, a multiple of the possible transmission intervals by other transmitting devices,

optionally, the candidate ranking first considers the temporal distance and then the received signal energy, or the candidate ranking first considers the received signal energy and then the temporal distance, or the candidate ranking is based on a function of the temporal distance and the received signal energy.

Proposition 14. A method according to one of Provisions 10 to 13, in which in the case when the radio resources cannot be selected to be used for data transmission, the method comprises the step of determining to reset the data in the case when the priority of the data available for is below a preemptive priority threshold, and in the case where data is not flushed, the method comprises performing a resource preemptive procedure to select radio resources to be used for data transmission from radio resources reserved by one or more others transmitting devices,

optionally, when performing the resource preemption procedure, the method comprises the step of selecting radio resources to be used for data transmission based on the priority of the reserved radio resources and / or the priority of the data to be transmitted and / or energy of the received signal, measured by the procedure for probing the resources in the radio resources of the corresponding subframes in the probing window, optionally, while the selection of radio resources in the preemptive procedure either first considers the priority and then the energy of the received signal from the reserved radio resources, or first considers the energy of the received signal, and then the priority of the reserved radio resources, or based on the priority function and the received signal energy of the reserved radio resources.

Statement 15. A method according to one of Provisions 10 to 14, the method comprising the steps of:

determining a channel occupancy ratio of the direct connection interface indicating the overflow level of the direct connection interface, and performing a data reset procedure before performing autonomous radio resource allocation based on the determined channel occupancy ratio of the direct connection interface, so as to determine whether data that is to become available for transmission, to be cleared or not, and in this case, in the case when the method determines not to discard data, a step is performed in which autonomous allocation of radio resources is performed,

optionally, during the data reset procedure, the method comprises the step of discarding data when it is determined that the priority of the data that becomes available for transmission is lower than the channel priority threshold, and the channel priority threshold depends on the determined channel occupancy ratio of the direct interface connections,

optionally, the transmitting device is configured by the radio base station controlling the transmitting device to perform or not to perform the data reset procedure, optionally, the configuration of the data reset procedure is separate for each of the plurality of resource pools used by the transmitting device to select radio resources for data transmission,

optionally in this case, the channel priority threshold is additionally dependent on the type of data that is made available for transmission, optionally the safety data-related channel priority threshold being below the non-safety-related channel priority threshold.

Statement 16. Transmitting device for transmitting scheduling destination and data via a direct connection interface for one or more receiving devices, wherein the transmitting device comprises:

a receiver and processor that, during operation, perform a resource sensing procedure to obtain information about radio resources that can be used by the transmitter to transmit scheduling assignments at a later point in time,

after the first data becomes available for transmission, the processor, during operation, performs an autonomous radio resource allocation procedure to select radio resources in the transmission window for transmitting the first data, and to select radio resources in the transmission window for transmitting the first scheduling assignment to based on information obtained through the resource probing procedure during the probing window before the first data became available for transmission, the first scheduling destination containing information on the selected radio resources in the transmission window for transmitting the first data,

a transmitter that, during operation, transmits a first scheduling assignment using the selected radio resources and transmits the first data using the selected radio resources, and

wherein the first scheduling assignment further indicates reserved radio resources that can be used at a later time by the transmitter to transmit the second scheduling assignment for the second data.

Position 17. A transmitter according to Position 16, wherein the autonomous radio resource allocation performed to select resources in the transmit window to be used for transmitting the first scheduling assignment comprises selecting radio resources in the primary subframes of the transmit window, preferably over radio resources in the secondary subframes transmission windows, and

in this case, the secondary subframes in the transmission window correspond to those subframes in the sounding window during which the transmitter did not perform the resource sounding procedure, and the primary subframes in the transmission window correspond to those subframes in the sounding window during which the transmitter performed the resource sounding procedure,

optionally, in this case, the processor, during operation, determines the secondary subframes as those subframes of the transmission window for which the resource sounding procedure did not receive all possible information during the sounding window,

optionally, the missing information for the secondary subframe contains:

- possible reservation of radio resources by other transmitting devices made during a subframe in the sounding window in which the transmitter did not perform the resource sounding procedure, optionally, the definition of secondary subframes is based on possible frequency of radio resource reservations that can be made by other transmitters, and / or

- information on the energy of the received signal in the radio resources of the subframe in the sounding window, in which the transmitter did not perform the resource sounding procedure.

Statement 18. A transmitter according to Statement 16 or 17, wherein the autonomous radio resource allocation performed to select radio resources in the transmit window to be used for transmitting the first scheduling assignment further comprises determining one or more primary transmit radio resource candidates in primary subframes and optionally determining one or more secondary radio candidate transmission resources in secondary subframes,

and in the case where more than one primary transmit radio candidate resources are present, the processor, during operation, performs ranking of the primary transmit radio candidate resource candidates, and in the case where more than one secondary transmit radio candidate resources are present, the processor, in operation, performs ranking of candidates of secondary transmit radio candidate resources, wherein the ranking of candidates of one or more primary transmit radio candidate resources is separate from the ranking of candidates of one or more secondary transmit radio candidate resources.

Provision 19 A transmitter according to one of Provisions 16 to 18, wherein the first scheduling assignment indicates radio resources reserved for transmission of the second scheduling assignment at a later point in time:

- in the case where the first scheduling assignment reserves radio resources that can be used at a later point in time to transmit second data by the transmitter, or

- by containing information that the first scheduling assignment reserves radio resources for transmission of the second scheduling assignment at a later point in time.

Position 20. Transmitting device according to one of Positions 16 to 19, wherein the transmitting device is configured by the radio base station controlling the transmitting device to reserve or not reserve radio resources for transmitting the second scheduling assignment at a later point in time, optionally while the configuration is performed by broadcasting a message by the radio base station in the cell where the transmitting device is located, or by means of a dedicated message transmitted by the radio base station to the transmitting device,

and optionally, the configuration as to whether or not to reserve radio resources for transmitting scheduling assignments is separate for each of a plurality of resource pools used by the transmitter to select radio resources for transmitting scheduling assignments.

Position 21. A transmitter according to one of Positions 16 to 20, in which the transmitter, during operation, retransmits the first scheduling assignment one or more times in the transmission window, and the processor, during operation, determines the number of retransmissions of the first assignment scheduling based on the priority of the first data and / or the overflow level of the direct connection interface,

optionally, the processor, during operation, performs an autonomous resource allocation procedure to select radio resources in the transmission window for one or more retransmissions of the first scheduling assignment, based on information obtained through the resource probing procedure during the probing window,

optionally wherein the first transmission of the first scheduling assignment and the one or more retransmissions of the first scheduling assignment comprise a common identification so as to allow the association of the first and retransmissions of the first scheduling assignment, optionally wherein the common identification identifies the transmitter and / or the transmitter data service that generates the first data,

optionally wherein one or more retransmissions of the first scheduling assignment have a predetermined relationship with the first transmission of the first scheduling assignment.

Statement 22. A method for a transmitting device for transmitting a scheduling destination and data via a direct connection interface to one or more receiving devices, the method comprising the following steps performed by the transmitting device, in which:

performing a resource sensing procedure to obtain information about radio resources that can be used by the transmitter to transmit scheduling assignments at a later point in time,

after the first data becomes available for transmission, perform an autonomous radio resource allocation procedure to select radio resources in the transmission window for transmitting the first data, and select radio resources in the transmission window for transmitting the first scheduling assignment based on the information obtained through the probing procedure resources during the probing window before the first data became available for transmission, while the first scheduling destination contains information on the selected radio resources in the transmission window for transmitting the first data,

transmit the first scheduling assignment using the selected radio resources, and transmit the first data using the selected radio resources, and

wherein the first scheduling assignment further indicates reserved radio resources that can be used at a later time by the transmitter to transmit the second scheduling assignment for the second data.

Statement 23 A method according to Statement 22, wherein autonomous radio resource allocation performed to select resources in a transmission window to be used for transmission of a first scheduling assignment comprises selecting radio resources in primary subframes of a transmission window, preferably over radio resources in secondary subframes of a window transmission, and

in this case, the secondary subframes in the transmission window correspond to those subframes in the sounding window during which the transmitter did not perform the resource sounding procedure, and the primary subframes in the transmission window correspond to those subframes in the sounding window during which the transmitter performed the resource sounding procedure,

optionally, the method comprises the step of determining the secondary subframes as those subframes of the transmission window for which the resource sounding procedure did not receive all possible information during the sounding window,

optionally, the missing information for the secondary subframe contains:

- possible reservation of radio resources by other transmitting devices made during a subframe in the sounding window in which the transmitter did not perform the resource sounding procedure, optionally, the definition of secondary subframes is based on possible frequency of radio resource reservations that can be made by other transmitters, and / or

- information on the energy of the received signal in the radio resources of the subframe in the sounding window, in which the transmitter did not perform the resource sounding procedure.

Statement 24. The method according to Statement 22 or 23, wherein the autonomous radio resource allocation performed to select radio resources in the transmit window to be used for the transmission of the first scheduling assignment further comprises determining one or more primary transmit radio resource candidates in the primary subframes, and optionally determining one or more secondary transmission radio candidate resources in secondary subframes,

and in a case where more than one primary transmission radio candidate resources are present, the method comprises ranking the candidates of the primary transmission radio candidate resources, and in the case where more than one secondary transmission radio candidate resources are present, the method comprises a step of performing the ranking of the candidates of the secondary transmit radio candidate resources, wherein the ranking of the candidates of the one or more primary transmit radio candidate resources is separate from the ranking of the candidates of the one or more secondary transmit radio candidate resources.

Statement 25 A method according to one of Provisions 22 to 24, wherein the first scheduling assignment indicates radio resources reserved for transmission of the second scheduling assignment at a later point in time:

- in the case where the first scheduling assignment reserves radio resources that can be used at a later point in time to transmit second data by the transmitter, or

- by containing information that the first scheduling assignment reserves radio resources for transmission of the second scheduling assignment at a later point in time.

Position 26: A method according to one of Positions 22 to 25, wherein the transmitting device is configured by the radio base station controlling the transmitting device to reserve or not reserve radio resources for transmitting the second scheduling assignment at a later time, optionally wherein the configuration is performed by broadcasting a message by the radio base station in the cell where the transmitting device is located, or by means of a dedicated message transmitted by the radio base station to the transmitting device,

and optionally, the configuration as to whether or not to reserve radio resources for transmitting scheduling assignments is separate for each of a plurality of resource pools used by the transmitter to select radio resources for transmitting scheduling assignments.

Position 27. The method according to one of Positions 22 to 26, further comprising the step of retransmitting the first scheduling assignment one or more times in the transmission window, and the method further comprising the step of determining the number of retransmissions of the first scheduling assignment to based on the priority of the first data and / or the overflow level of the direct connection interface,

optionally, the method comprises the step of performing an autonomous resource allocation procedure to select radio resources in a transmission window for one or more retransmissions of the first scheduling assignment based on information obtained through the resource sounding procedure during the sounding window,

optionally wherein the first transmission of the first scheduling assignment and the one or more retransmissions of the first scheduling assignment comprise a common identification so as to allow the association of the first and retransmissions of the first scheduling assignment, optionally wherein the common identification identifies the transmitter and / or the transmitter data service that generates the first data,

optionally wherein one or more retransmissions of the first scheduling assignment have a predetermined relationship with the first transmission of the first scheduling assignment.

Claims (27)

1. An integrated circuit that, in operation, controls the process of the transmitter to determine the radio resources to be used to transfer data from the transmitter through a direct interface to one or more receiving devices, which process comprises: performing a resource probe procedure in order to obtain information about radio resources that can be used for data transmission by the transmitting device at a later point in time, after the data becomes available for transmission, performing an autonomous radio resource allocation to select radio resources in the transmit window to be used for data transmission based on information obtained through the resource sounding procedure during the sounding window before said data became available for transmission, and wherein the autonomous radio resource allocation comprises the selection of radio resources in the primary subframes of the transmission window with priority over the radio resources in the secondary subframes of the transmission window, and the secondary subframes in the transmission window correspond to those subframes in the probing window, during which the transmitter did not perform the resource sounding procedure, and the primary subframes in the transmission window correspond to those subframes in the probing window during which the transmitter performed the resource sounding procedure. 2. The integrated circuit of claim 1, wherein the resource sensing procedure comprises: - in order to determine the radio resources that are reserved by other transmitting devices, said process, during its execution, monitors for scheduling information that is transmitted by other transmitting devices, indicating radio resources reserved by these other transmitting devices for a later point in time, - measuring the received signal energy in radio resources to identify radio resources that are used by other transmitting devices for transmission. 3. The integrated circuit of claim 1, wherein said process, during its execution, determines the secondary subframes as those subframes of the transmission window for which the resource sounding procedure has not received all possible information during the sounding window, wherein the missing information for the secondary subframe contains: - possible radio resource reservation by other transmitters made during a subframe in the sounding window in which the transmitter did not perform the resource sounding procedure, and / or where the determination of secondary subframes is based on possible radio resource reservation periods that can be made by these other transmitters, and / or - information on the energy of the received signal in the radio resources of the subframe in the sounding window, in which the transmitter did not perform the resource sounding procedure. 4. The integrated circuit of claim 1, wherein the autonomous radio resource allocation further comprises determining one or more potentially suitable primary radio transmission resources in primary subframes and / or determining one or more potentially suitable secondary radio transmission resources in secondary subframes, and in the case where there is more than one potentially suitable primary radio transmission resource, said process during its execution ranks the potentially suitable primary radio transmission resources, and in the case where there is more than one potentially suitable secondary radio transmission resource, said process during its execution ranks potentially suitable secondary radio transmission resources, wherein the ranking of one or more potentially suitable primary radio transmission resources is separate from the ranking of one or more potentially suitable secondary radio transmission resources, the ranging takes into account the temporal distance of the potentially suitable radio resource from the moment in time when the data became available for transmission, as well as the prediction of the energy of the received signal obtained by means of the resource probing procedure for the radio resources to be ranged, wherein the prediction of the received signal energy for the radio resources to be ranked is based on measurements of the received signal energy of the corresponding radio resources in all subframes of the sounding window or is based on measurements of the received signal energy of the corresponding radio resources in the subframes of the sounding window associated with the subframe whose radio resources are to be ranged , where these associated subframes are those subframes of the sounding window that have a distance from the radio resources to be ranged, a multiple of the possible transmission frequencies of other transmitters, the ranging first takes into account the temporal distance and then the energy of the received signal, or the ranging first takes into account the energy of the received signal and then the temporal distance, or the ranging is based on a function of the temporal distance and the energy of the received signal. 5. The integrated circuit of claim 1, wherein said process, when performing a data transmission or transmission of a scheduling assignment for data transmission in a subframe, does not perform a resource sounding procedure in that subframe. 6. The integrated circuit according to claim 1, in which in the case when the radio resources cannot be selected for their use for data transmission, said process during its execution determines to reset the data in the case when the priority of the data available for transmission is below the threshold the preemptive priority values, and in the case when data is not flushed, said process, during its execution, performs a resource preemptive procedure to select radio resources to be used for data transmission from among radio resources reserved by one or more of the other transmitting devices, wherein said process, when performing the resource preemption procedure, selects the radio resources to be used for data transmission based on the priority of the reserved radio resources and / or the priority of the data to be transmitted and / or the energy of the received signal measured by the resource sensing procedure in the radio resources of the corresponding subframes in the sounding window, while, optionally, the choice of radio resources in the resource preemptive procedure either first considers the priority and then the received signal energy of the reserved radio resources, or first considers the received signal energy and then the priority of the reserved radio resources, or is based on functions of priority and energy of the received signal of the reserved radio resources. 7. The integrated circuit of claim 1, wherein said process, when executed, determines a channel occupancy rate of the direct connect interface indicating the overflow level of the direct connect interface, wherein the process, during its execution, performs a data reset procedure prior to performing autonomous radio resource allocation based on of this determined channel occupancy ratio of the direct connection interface to determine whether the data that becomes available for transmission should be discarded or not, and in the case when the said process determines not to discard the data, this process performs autonomous allocation of radio resources, wherein during the data reset procedure, said process resets data upon determining that the priority of the data that becomes available for transmission is lower than the channel priority threshold, the channel priority threshold being dependent on said determined channel occupancy ratio of the direct connection interface, wherein the transmitting device is configured by the radio base station controlling the transmitting device to perform or not to perform the data reset procedure, while, optionally, the configuration of the data reset procedure is separate for each of the plurality of resource pools used by the transmitting device to select radio resources for transmission data, wherein the channel priority threshold is further dependent on the type of data that is made available for transmission, the security data-related channel priority threshold being lower than the non-security-related channel priority threshold. 8. The integrated circuit of claim 1, wherein the autonomous radio resource allocation comprises excluding radio resources reserved by other transmitters from the plurality of radio transmission resources, and / or wherein the potentially suitable radio resource in the subframe comprises one or more resource blocks that are contiguous in the frequency area. 9. The integrated circuit of claim 1, wherein the sensing window taken into account for the autonomous allocation of radio resources comprises radio time-frequency resources starting at a predetermined time before the data becomes available for transmission and ending at the time when the data become available for transmission, and the transmit window contains radio time-frequency resources starting in the initial subframe, which is immediately after the subframe in which the data became available for transmission, and ending in a subframe, which is at a predetermined distance from the initial subframe, this distance depending on the delay requirements in in relation to data that becomes available for transmission to be performed by the transmitting device.

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