JP6990749B2 - Improved radio resource selection and sensing for V2X transmission - Google Patents

Description

The present disclosure relates to an improved transmit device for performing radio resource selection and sensing procedures. The present disclosure provides corresponding methods and devices for the present invention.

[Long Term Evolution (LTE)]
Third-generation mobile communication systems (3Gs) based on WCDMA® wireless access technology are being deployed on a wide scale around the world. High-Speed Downlink Packet Access (HSDPA) and High-Speed Uplink Packet Access (HSUPA) are the first steps in enhancing, developing and evolving this technology. Uplink Packet Access)) has been introduced, which provides extremely competitive wireless access technology.

3GPP has introduced a new mobile communication system called Long Term Evolution (LTE) with the aim of meeting the ever-increasing demand from users and ensuring competitiveness for new wireless access technologies. LTE is designed to provide the carriers required for high-speed data and media transmission and high-capacity voice support over the next decade. The ability to provide high bit rates is an important measure in LTE.

The specifications of work items (WI: work item) related to LTE, called E-UTRA (Evolved UMTS Terrestrial Radio Access (UTRA)) and UTRAN (UMTS Terrestrial Radio Access Network), are finally released 8 (LTE release 8). ) Will be published. LTE systems are packet-based, efficient radio access and radio access networks that provide all IP-based functionality at low latency and low cost. In LTE, multiple scalable transmit bandwidths (eg, 1.4 MHz, 3.0 MHz, 5.0 MHz, 10.0 MHz, 15.0 MHz) are used to achieve flexible system deployments using a given spectrum. And 20.0 MHz) are specified. Radio access based on OFDM (Orthogonal Frequency Division Multiplexing) is adopted as the downlink. This is because such radio access is inherently less susceptible to multipath interference (MPI) due to its low symbol rate, uses cyclic prefixes (CPs), and has a variety of transmissions. This is because it can support bandwidth configurations. Wireless access based on SC-FDMA (Single-Carrier Frequency Division Multiple Access) is adopted as the uplink. This is because, considering that the transmission output of the user equipment (UE) is limited, it is prioritized to provide a wide coverage area rather than improving the peak data rate. In LTE Release 8/9, a number of major packet radio access technologies (eg MIMO (Multiple Input Multiple Output) channel transmission technology) have been adopted to achieve a highly efficient control signaling structure.

[LTE architecture]
FIG. 1 shows the overall architecture of LTE. E-UTRAN consists of eNodeB, which terminates E-UTRA's user plane (PDCP / RLC / MAC / PHY) and control plane (RRC) protocols for user equipment (UE). .. The eNodeB (eNB) is a physical (PHY) layer, a medium access control (MAC) layer, a radio link control (RLC) layer, and a packet data control protocol (PDCP) layer. (These layers include user plane header compression and encryption capabilities). The eNB also provides a radio resource control (RRC) function corresponding to the control plane. eNB provides radio resource management, admission control, scheduling, negotiated quality of service (QoS) implementation, cell information broadcasting, user plane data and control plane data encryption / decryption, downlink / Performs many functions such as compressing / restoring uplink user plane packet headers. A plurality of eNodeBs are connected to each other by an X2 interface.

Further, the plurality of eNodeBs are EPC (Evolved Packet Core) by S1 interface, more specifically, MME (Mobility Management Entity) by S1-MME, and serving gateway (SGW: Serving Gateway) by S1-U. It is connected to the. The S1 interface supports a many-to-many relationship between the MME / serving gateway and the eNodeB. While routing and forwarding user data packets, the SGW acts as a mobility anchor for the user plane during handover between eNodeBs, and also an anchor for mobility between LTE and another 3GPP technology (S4). It functions as (relaying traffic between the 2G / 3G system and the PDN GW) by terminating the interface. The SGW terminates the downlink data path for the idle user equipment and triggers paging when the downlink data arrives at the user equipment. The SGW manages and stores the context of the user equipment (eg, IP bearer service parameters, or network internal routing information). In addition, the SGW performs duplication of user traffic in the case of lawful interception.

The MME is the main control node of the LTE access network. The MME is responsible for tracking and paging procedures (including retransmissions) of user equipment in idle mode. The MME is involved in the bearer activation / deactivation process, and also during the initial attachment and during the in-LTE handover with the relocation of the Core Network (CN) node, the user equipment. It also plays a role in selecting SGW. The MME is responsible for authenticating the user (by interacting with the HSS). Non-Access Stratum (NAS) signaling is terminated at the MME. The MME also plays a role of generating a temporary ID and assigning it to the user device. The MME checks the authentication of the user equipment to enter the PLMN (Public Land Mobile Network) of the service provider, and enforces the roaming restriction of the user equipment. The MME is the end point in the network in the encryption / integrity protection of NAS signaling and manages the security key. Legal interception of signaling is also supported by MME. In addition, the MME provides a control plane function for mobility between the LTE access network and the 2G / 3G access network, terminating the S3 interface from the SGSN. In addition, the MME terminates the S6a interface towards the home HSS for roaming user equipment.

[Component carrier structure in LTE]
The downlink component carriers of the 3GPP LTE system are further divided in the time-frequency domain in so-called subframes. In 3GPP LTE, each subframe is divided into two downlink slots as shown in FIG. The first downlink slot comprises a control channel region (PDCCH region) within the first OFDM symbol. Each subframe consists of a given number of OFDM symbols in the time domain (12 or 14 OFDM symbols in 3GPP LTE (Release 8)), and each OFDM symbol extends over the bandwidth of the component carrier. Therefore, each OFDM symbol is composed of several modulation symbols transmitted by each subcarrier. In LTE, the transmission signal in each slot is described by a resource grid of N ^DL _RB × N ^RB _sc lines and N ^DL _symb OFDM symbols. N ^DL _RB is the number of resource blocks in the bandwidth. The N ^DL _RB depends on the downlink transmission bandwidth set in the cell and satisfies N ^{min, DL} _RB ≤ N ^DL _RB ≤ N ^{max, DL} _RB . In this case, N ^{min, DL} _RB = 6 and N ^{max, DL} _RB = 110 are the minimum and maximum downlink bandwidths supported by the specifications of the current version, respectively. ^NRB _sc is the number of subcarriers in one resource block. In the case of a normal cyclic prefix subframe structure, ^NRB _sc = 12 and N ^DL _symb = 7.

For example, assuming a multi-carrier communication system using OFDM, for example, as used in 3GPP LTE, the smallest unit of resources that can be allocated by the scheduler is one "resource block". As illustrated in FIG. 2, a physical resource block (PRB) is a continuous OFDM symbol (for example, 7 OFDM symbols) in the time domain and a continuous subcarrier (for example, 12 of component carriers) in the frequency domain. Defined as a book subcarrier). Therefore, in 3GPP LTE (Release 8), the physical resource block is composed of resource elements and corresponds to one slot in the time domain and 180 kHz in the frequency domain (more details on the downlink resource grid can be found in, for example, Non-Patent Document 1). See Section 6.2 (available on the 3GPP website (http://www.3gpp.org) and incorporated herein by reference).

One subframe consists of two slots. There are 14 OFDM symbols in the subframe when the so-called "normal" CP (Cyclic Prefix) is used, and 12 in the subframe when the so-called "extended" CP is used. There is an OFDM symbol of. For technical purposes, in the following, the same continuous subcarrier-equivalent time-frequency resource that spans the entire subframe is referred to as a "resource block pair" or a synonymous "RB pair". Alternatively, it is called a "PRB pair".

The term "Component Carrier" refers to a combination of several resource blocks in the frequency domain. In future releases of LTE, the term "component carrier" will no longer be used, and instead its terminology will be changed to "cell" to indicate a combination of downlink resources and optionally uplink resources. The link between the carrier frequency of the downlink resource and the carrier frequency of the uplink resource is indicated in the system information transmitted by the downlink resource.

Similar assumptions about the structure of component carriers apply to subsequent releases.

[Carrier Aggregation in LTE-A for Wider Bandwidth Support]
At the World Radiocommunication Conference 2007 (WRC-07), the frequency spectrum of IMT-Advanced was determined. Although the overall frequency spectrum for IMT-Advanced has been determined, the frequency bandwidth actually available will vary by region or country. However, following the determination of the available frequency spectrum outline, standardization of wireless interfaces has begun in the 3GPP (3rd Generation Partnership Project). At the 3GPP TSG RAN # 39 meeting, the description of study items regarding "Further Advancements for E-UTRA (LTE-Advanced)" was approved. This study item covers the technical elements that should be considered in the evolution and development of E-UTRA (for example, to meet the requirements of IMT-Advanced).

The LTE advanced system can support 100 MHz, while the LTE system can only support 20 MHz. Today, the lack of radiospectrum becomes a bottleneck in the development of wireless networks, and as a result, it is difficult to find a wide enough spectral band for LTE advanced systems. Therefore, there is an urgent need to find a way to obtain a wider radiospectral band, where a possible answer is the carrier aggregation function.

In carrier aggregation, two or more component carriers are aggregated to support a wider transmit bandwidth of up to 100 MHz. In the LTE-Advanced system, several cells in the LTE system are aggregated into one wider channel. This channel is wide enough for 100 MHz, even if these cells in LTE are in different frequency bands.

At the very least, all component carriers can be configured to be LTE Release 8/9 compatible when the bandwidth of the component carriers does not exceed the supported bandwidth of the LTE Release 8/9 cells. Not all component carriers aggregated by the user equipment are necessarily LTE Release 8/9 compatible. Existing mechanisms (eg, burring) can be used to prevent Release 8/9 user equipment from camping on component carriers.

The user equipment can simultaneously receive or transmit one or more component carriers (corresponding to a plurality of serving cells) depending on the capabilities of the user equipment. LTE-A Release 10 user equipment with receive and / or transmit capabilities for carrier aggregation can receive and / or transmit simultaneously on multiple serving cells. In contrast, LTE Release 8/9 user equipment can receive and transmit on only one serving cell if the component carrier structure complies with Release 8/9 specifications.

Carrier aggregation is supported on both continuous and discontinuous component carriers, with each component carrier up to 110 resource blocks in the frequency domain (using 3GPP LTE (Release 8/9) numerology). Limited to.

Configure 3GPP LTE-A (Release 10) compatible user equipment to aggregate different numbers of component carriers with different bandwidths, possibly uplinks and downlinks, transmitted from the same eNodeB (base station). It is possible to do. The number of downlink component carriers that can be set depends on the downlink aggregation capability of the user equipment. Conversely, the number of uplink component carriers that can be configured depends on the uplink aggregation capabilities of the user equipment. At this time, it is not possible to set a mobile terminal to have more uplink component carriers than downlink component carriers. In a typical TDD deployment, the number of component carriers and the bandwidth of each component carrier are the same for the uplink and downlink. Component carriers originating from the same eNodeB do not have to provide the same coverage.

The distance between the center frequencies of the component carriers that are continuously aggregated is an integral multiple of 300 kHz. This is to maintain compatibility with the 100 kHz frequency raster of 3GPP LTE (Release 8/9) while maintaining the orthogonality of the subcarriers at 15 kHz intervals. Depending on the aggregation scenario, n × 300 kHz spacing can be facilitated by inserting a small number of unused subcarriers between successive component carriers.

The effect of aggregating multiple carriers only extends to the MAC layer. The MAC layer requires one HARQ entity for each component carrier to be aggregated, both uplink and downlink. The maximum number of transport blocks per component carrier is one (when SU-MIMO on the uplink is not used). The transport block and its HARQ retransmission (when it occurs) must be mapped to the same component carrier.

When carrier aggregation is set, the mobile terminal has only one RRC connection to the network. When establishing / reestablishing an RRC connection, one cell has a security input (one ECGI, one PCI, and one ARFCN) and a non-access layer (NAS: non-access), similar to LTE release 8/9. stratum) Provides mobility information (eg TAI). After establishing / reestablishing an RRC connection, the component carrier corresponding to that cell is referred to as a downlink primary cell (PCell). In the connected state, one downlink PCell (DL PCell) and one uplink PCell (UL PCell) are always set per user device. In a configured set of component carriers, the other cells are called secondary cells (SCell), and the carriers of the SCell are the downlink secondary component carrier (DL SCC) and the uplink secondary component carrier (UL SCC). be. Up to 5 serving cells (including PCell) can be set for one UE.

[MAC layer / MAC entity, RRC layer, physical layer]
The LTE Layer 2 user / control plane protocol stack comprises four sublayers: RRC, PDCP, RLC, and MAC. The medium access control (MAC) layer is the lowest sublayer in the Layer 2 architecture of the LTE radio protocol stack and is defined, for example, by Non-Patent Document 2 which is a 3GPP technical standard. The lower physical layer is connected through the transport channel and the upper RLC layer is connected through the logical channel. The MAC layer therefore performs multiplexing and demultiplexing between the logical channel and the transport channel. The MAC layer on the transmitting side builds a MAC PDU (also known as a transport block) from the MAC PDU received through the logical channel, and the MAC layer on the receiving side restores the MAC SDU from the MAC PDU received through the transport channel. do.

The MAC layer provides data transmission services to the RLC layer through a logical channel (see Sections 5.4 and 5.3 of Non-Patent Document 2 incorporated herein by reference), which logical channels are It is either a control logical channel that conveys control data (eg, RRC signaling) or a traffic logical channel that conveys user plane data. On the other hand, data from the MAC layer is exchanged with the physical layer through transport channels (classified as downlinks or uplinks). Data is multiplexed into transport channels depending on the transmission method over the radio.

The physical layer is responsible for actually transmitting data and control information through the air interface, that is, the physical layer conveys all information from the MAC transport channel on the transmitting side through the air interface. Some important functions performed by the physical layer include coding and modulation, link adaptation (AMC), power control, cell search (for the purpose of initial synchronization and handover), and others for the RRC layer. Measurements (inside the LTE system and between systems). The physical layer performs transmissions based on transmission parameters (modulation scheme, coding rate (ie, modulation / coding scheme (MCS)), number of physical resource blocks, etc.). Further information on the function of the physical layer is described in Non-Patent Document 3 (incorporated herein by reference).

The radio resource control (RRC) layer controls the communication between the UE and the eNB on the radio interface and the mobility of the UE moving across several cells. The RRC protocol also supports the transmission of NAS information. For UEs with RRC_IDLE, RRC supports notification of incoming calls from the network. RRC connection control provides all procedures related to establishing, modifying, and disconnecting RRC connections (paging, setting and reporting measurements, setting radio resources, initial security activation, signaling radio bearer (SRB) and Covers radio bearers (including the establishment of Data Radio Bearers (DRBs)) that carry user data.

The Radio Link Control (RLC) sublayer mainly has an ARC (Automatic Repeat Request) function and also supports data division and concatenation. That is, the RLC layer performs framing of the RLC SDU to the size indicated by the MAC layer. The latter two minimize the protocol overhead regardless of the data rate. The RLC layer is connected to the MAC layer via a logical channel. Each logical channel carries different types of traffic. The layer above the RLC layer is generally a PDCP layer, but in some cases an RRC layer. That is, RRC messages transmitted on the logical channels BCCH (Broadcast Control Channel), PCCH (Paging Control Channel), and CCCH (Common Control Channel) do not require security protection and therefore bypass the PDCP layer to the RLC layer. Passed directly.

[Uplink access method in LTE]
In uplink transmission, the user terminal needs to transmit with high power efficiency in order to maximize the coverage. As the uplink transmission method of E-UTRA, a method that combines single carrier transmission and FDMA with dynamic bandwidth allocation is selected. The main reason for choosing single-carrier transmission is that the peak to average power ratio (PAPR) is lower compared to multi-carrier signals (OFDM), and the efficiency of the power amplifier is improved accordingly. This is because the coverage is also improved (the data rate is higher for the given terminal peak power). At each time interval, the eNodeB allocates the user a unique time / frequency resource for transmitting user data, thereby ensuring orthogonality within the cell. Orthogonal multiple access on the uplink increases spectral efficiency by eliminating in-cell interference. Interference caused by multipath propagation is dealt with in the base station (eNodeB) by inserting a cyclic prefix in the transmission signal.

The basic physical resource used to transmit the data consists of a frequency resource of size BW _grant over one time interval (eg subframe) (encoded information bits are mapped to this resource). ). The subframe (also referred to as a transmission time interval (TTI)) is the minimum time interval for transmitting user data. However, by concatenating the subframes, it is also possible to allocate the frequency resource BW _grant to the user for a time longer than 1 TTI.

[Layer 1 / Layer 2 control signaling]
L1 / L2 control signaling for the purpose of notifying the user to be scheduled of the user's allocation status, transport format, and other transmission-related information (eg, HARQ information, Transmit Power Control (TPC) command). Is sent downlink with the data. The L1 / L2 control signaling is multiplexed with the downlink data within the subframe (assuming that the user allocation can change on a subframe basis). It should be noted that user allocation can also be executed on a TTI (transmission time interval) basis. Note that in that case the TTI length can be an integral multiple of the subframe. The TTI length can be constant for all users in the service area, different for different users, or even dynamic for each user. L1 / L2 control signaling generally only needs to be transmitted once per TTI. In the following, it is assumed that TTI is equal to one subframe without loss of generality.

The L1 / L2 control signaling is transmitted on the physical downlink control channel (PDCCH). The PDCCH conveys a message as downlink control information (DCI). The DCI most often contains resource allocation and other control information to groups of mobile terminals or UEs. Several PDCCHs can be transmitted within one subframe.

Information sent by L1 / L2 control signaling for the purpose of allocating uplink radio resources or downlink radio resources (particularly LTE (-A) Release 10) can generally be classified into the following items.
-User Identity: Indicates the user to be assigned. This information is generally included in the checksum by masking the CRC with the user's identification information.
-Resource allocation information: Indicates the resource allocated to the user (eg, resource block (RB)). Alternatively, this information is referred to as resource block assignment (RBA). The number of resource blocks (RBs) allocated to users can be dynamic.
-Carrier indicator: When the control channel transmitted by the first carrier allocates resources related to the second carrier (that is, resources of the second carrier or resources related to the second carrier). Used (cross-carrier scheduling).
-Modulation and Coding Scheme: Determines the modulation method and coding rate to be adopted.
-HARQ information: New Data Indicator (NDI) or Redundancy Version (RV), which are particularly useful when retransmitting a data packet or part thereof.
-Power control command: Adjusts the transmission power when transmitting the data or control information of the uplink to be allocated.
-Reference signal information: Applicable cyclic shift or orthogonal cover code (OCC) index, etc. used to send or receive the reference signal to be assigned.
-Uplink Allocation Index or Downlink Allocation Index: Used to identify the order of allocation and is particularly useful in TDD systems.
-Hopping information: For example, information on whether to apply resource hopping for the purpose of increasing frequency diversity and how to apply it.
-CSI request: Used to trigger the allocated resource to send Channel State Information.
-Multi-cluster information: A flag used to indicate and control whether to send in a single cluster (a continuous set of RBs) or a multi-cluster (a contiguous set of at least two contiguous resource blocks). Is. Multi-cluster allocation was introduced with 3GPP LTE- (A) Release 10.

It should be noted that the above list is not exhaustive and, depending on the DCI format used, it may not be necessary to include all of the listed information items in each PDCCH transmission.

The downlink control information takes the form of several formats, which differ in overall size from the information contained in the fields described above. The various DCI formats currently defined in LTE are as follows and are available in Section 5.3.3.1 of Non-Patent Document 4 (3GPP website (http://www.3gpp.org)). And is incorporated herein by reference) in detail. Non-Patent Document 4, which is incorporated herein by reference, defines control information for the sidelink interface in section 5.4.3.

[Semi-Persistent Scheduling (SPS)]
For downlinks and uplinks, the scheduling eNodeB is dynamic to the user equipment via the L1 / L2 control channel (PDCCH) to which the user equipment is addressed via their particular C-RNTI at each transmission time interval. Allocate resources to. As already mentioned above, the CRC of the PDCCH is masked by the C-RNTI of the addressed user device (so-called dynamic PDCCH). Only user equipment with a matching C-RNTI can correctly decode the PDCCH content. That is, the CRC check is positive. This type of PDCCH signaling is also referred to as a dynamic (scheduled) grant. The user equipment monitors the L1 / L2 control channels for dynamic grants at each transmission time interval to discover allocated and possible allocations (downlinks and uplinks).

In addition to this, E-UTRAN may persistently allocate uplink / downlink resources for the first HARQ transmission. If necessary, the retransmission is explicitly signaled via the L1 / L2 control channel. This type of operation is called semi-persistent scheduling (SPS) because retransmissions are dynamically scheduled. That is, resources are allocated to user equipment on a semi-persistent basis (semi-persistent resource allocation). The advantage is that PDCCH resources for the initial HARQ transmission are saved. Semi-persistent scheduling can be used in PCell in Release 10, but not in SCell.

An example of a service that can be scheduled using semi-persistent scheduling is voice over IP (VoIP). Every 20 ms, VoIP packets are generated in the codec during a call. Therefore, the eNodeB may be able to continuously allocate uplink or downlink resources every 20 ms. It can then be used for the transmission of voice over IP packets. In general, semi-persistent scheduling is beneficial for predictable traffic behavior, i.e., services with a constant bit rate, and packet arrival times are periodic.

The user equipment also monitors the PDCCH in the subframe to which the resource for the first transmission is continuously allocated. A dynamic (scheduled) grant, ie a PDCCH with a C-RNTI masked CRC, can invalidate semi-persistent resource allocation. If the user equipment discovers its C-RNTI in the L1 / L2 control channel in the subframe with the allocated semi-persistent resources, this L1 / L2 control channel allocation is the transmission time interval. Disable persistent resource allocation for and user equipment follows dynamic grants. When the user device does not discover the dynamic grant, the user device sends / receives according to the semi-persistent resource allocation.

The setting of semi-persistent scheduling is done by RRC signaling. For example, the periodicity of persistent allocation, eg PS_PERIOD, is signaled within radio resource control (RRC) signaling. Persistent allocation activation, as well as exact timing, as well as physical resources and transmission format parameters are transmitted via PDCCH signaling. When semi-persistent scheduling is activated, the user equipment follows semi-persistent resource allocation according to SPS activation PDCCH per PS_PERIOD. In essence, the user device stores SPS activation PDCCH content and follows the PDCCH in a signaled cycle.

Individual identification information is introduced to distinguish dynamic PDCCH from PDCCH (also called SPS activation PDCCH) that activates semi-persistent scheduling. Basically, the CRC of the SPS activation PDCCH is masked with this additional identification information, hereinafter referred to as SPS C-RNTI. The size of SPS C-RNTI is also 16 bits, which is the same as that of normal C-RNTI. In addition, the SPS C-RNTI is also user device specific, i.e., each user device configured for semi-persistent scheduling is assigned a unique SPS C-RNTI.

If the user equipment detects that the semi-persistent resource allocation has been activated by the corresponding SPS activation PDCCH, the user equipment stores the PDCCH content (ie, semi-persistent resource allocation) and semi-persistently stores it. It is applied at each continuous scheduling interval, that is, in the cycle signaled via the RRC. As already mentioned, the only thing that is signaled in the dynamic allocation, ie dynamic PDCCH, is the "one-time allocation". Retransmission of SPS allocation is also signaled using SPS C-RNTI. An NDI (new data indicator) bit is used to distinguish SPS activations from SPS retransmissions. SPS activation is indicated by setting the NDI bit to 0. An SPS PDCCH with an NDI bit set to 1 indicates a retransmission for a semi-persistently scheduled first transmission.

Similar to activation of semi-persistent scheduling, eNodeB may also deactivate semi-persistent scheduling, also known as SPS resource deactivation. There are several options for how semi-persistent scheduling deallocation can be signaled. One option would be to use PDCCH signaling with some PDCCH fields set to some predefined values, namely SPS PDCCH indicating zero size resource allocation. Another option would be to use MAC control signaling.

[LTE device-to-device (D2D: Device to Device) proximity services (ProSe: Proximity Services)]
Accessibility-based applications and services are a new trend in social technology. Areas identified include commercial services and services related to public safety that are of interest to businesses and users. By introducing proximity services (ProSe) capabilities to LTE, the 3GPP industry will be able to serve this growing market while at the same time addressing the urgent needs of some public safety communities that work together to use LTE. I can respond.

D2D communication is a technical element introduced by LTE Release 12. This technique can increase spectral efficiency in D2D as an underlay for cellular networks. For example, if the cellular network is LTE, all physical channels carrying data use SC-FDMA in D2D signaling. In D2D communication, user equipment transmits data signals to each other through a direct link using cellular resources, without going through a radio base station. Throughout the invention, the terms "D2D", "ProSe", and "sidelink" are synonymous.

D2D communication in LTE focuses on two areas: discovery and communication.

In ProSe Direct Discovery, a ProSe-enabled user device uses an E-UTRA direct radio signal to another nearby ProSe-enabled user device via a PC5 interface. It is defined as the procedure used to discover.

In D2D communication, UEs use cellular resources to transmit data signals to each other over a direct link without going through a base station (BS). The D2D user communicates directly, but remains under the control of the base station (at least when within eNB coverage). Therefore, in D2D, system performance can be improved by reusing cellular resources.

D2D is assumed to operate in the uplink LTE frequency band (for FDD) or in the uplink subframes of cells providing coverage (for TDD, except when out of coverage). .. Moreover, D2D transmission / reception does not use full duplex in a given carrier. From the point of view of individual user equipment, D2D signal reception and LTE uplink transmission do not use full duplex in a given carrier (ie, D2D signal reception and LTE uplink transmission cannot be performed simultaneously).

In D2D communication, when one particular UE 1 is in the role of transmission (transmitting user equipment or transmitting terminal), UE 1 transmits data and another UE 2 (receiving user equipment) receives it. UE1 and UE2 can exchange the role of transmission and the role of reception. Transmission from UE1 can be received by one or more UEs (such as UE2).

[Layer 2 link for ProSe direct communication]
Briefly, one-to-one ProSe direct communication is achieved by establishing a secure Layer 2 link between the two UEs through PC5. Each UE has a Layer 2 ID for unicast communication. This layer 2 ID is the Source Layer-2 ID (source layer 2 ID) field of each frame transmitted by the UE on the layer 2 link and the Destination Layer-2 ID (destination) of each frame received by the UE on the layer 2 link. It is included in Layer 2 ID). The UE needs to ensure that the Layer 2 ID for unicast communication is unique, at least within the local range. Therefore, the UE handles a Layer 2 ID conflict with an adjacent UE using an unspecified mechanism (eg, assigning itself a new Layer 2 ID for unicast communication when a collision is detected). Should be configured to. Layer 2 links for one-to-one ProSe direct communication are identified by a combination of layer 2 IDs of the two UEs. That is, the UE can participate in multiple Layer 2 links for one-to-one ProSe direct communication using the same Layer 2 ID.

One-to-one ProSe direct communication comprises the following procedure, as detailed in Section 7.1.2. (Incorporated herein by reference) of Non-Patent Document 5.
・ Establish a secure layer 2 link through PC5 ・ Assign IP address / prefix ・ Maintain and manage layer 2 link through PC5 ・ Release layer 2 link through PC5

FIG. 3 shows how to establish a secure Layer 2 link through the PC5 interface.
1. 1. The UE-1 sends a Direct Communication Request message to the UE-2 for the purpose of triggering mutual authentication. In order to execute step 1, the link start side (UE-1) needs to know the layer 2 ID of the other side (UE-2). As an example, the link initiator can recognize the other party's Layer 2 ID by first performing a discovery procedure or by participating in one-to-many ProSe communication including the other party.
2. 2. UE-2 initiates the procedure for mutual authentication. When the authentication procedure is completed normally, the establishment of the secure layer 2 link through the PC 5 is completed.

UEs involved in a single (non-relayed) one-to-one communication can also use link-local addresses. The PC5 signaling protocol supports a keepalive feature used to detect when the UE is not within ProSe communication range. Therefore, such a UE can proceed to the implicit release of the layer 2 link. The disconnection of the layer 2 link through the PC 5 can be performed by using the Disconnect Request message sent to the other UE. The other UE also deletes all relevant context data. Upon receiving the disconnect request message, the other UE responds with a Disconnect Response message and deletes all contextual data associated with the Layer 2 link.

[Identification information related to ProSe direct communication]
Section 8.3 of Non-Patent Document 6 defines the following identification information for use in ProSe direct communication.
-SL-RNTI (Side-link wireless network temporary identifier): Unique identification information used for scheduling ProSe direct communication-Source Layer 2 ID: The sender of data in side-link ProSe direct communication Identify. The source Layer 2 ID is 24 bits long and is used with the ProSe Layer 2 destination ID and LCID to identify the RLC UM and PDCP entities in the receiver.
-Destination Layer 2 ID: Identify the target person of the data in the side link ProSe direct communication. The destination layer 2 ID has a 24-bit length and is divided into two bit strings in the MAC layer.
-One bit string is the lowest portion (8 bits) of the destination layer 2 ID and is transferred to the physical layer as the side link control layer 1 ID. It is used to identify the intended audience for data in sidelink control and to filter packets at the physical layer.
-The second bit string is the uppermost part (16 bits) of the destination layer 2 ID and is transmitted in the MAC header. It is used to filter packets at the MAC layer.

Non-access layer signaling is required to form groups in the UE and to configure source layer 2 IDs, destination layer 2 IDs, and sidelink control layer 1 IDs. These identifications are provided by the higher layers or are derived from the identifications provided by the higher layers. For group cast and broadcast, the ProSe UE ID provided by the higher layer is used directly as the source layer 2 ID, and the ProSe layer 2 group ID provided by the higher layer is used directly as the destination layer 2 ID in the MAC layer. Will be done. For one-to-one communication, the higher layer provides the source layer 2 ID and the destination layer 2 ID.

[Wireless resource allocation in proximity service]
From the viewpoint of the transmitting UE, the UE corresponding to the proximity service (Proximity-Service-enabled UE. ProSe compatible UE) can operate in the following two modes of resource allocation.

Mode 1 is because the UE requests transmission resources from the eNB (or release 10 relay node) and the eNodeB (or release 10 relay node) sends direct data and direct control information (eg, scheduling allocation). Refers to the eNB scheduling resource allocation mode that sequentially schedules the resources used by the UE. The UE needs to be RRC_CONTECTED in order to send data. In particular, the UE normally sends a scheduling request (D-SR or random access) to the eNB, followed by a sidelink buffer status report (BSR) (also in the "Transmission processedure for D2D communication" chapter below. reference). Based on the BSR, the eNB may determine that the UE has data for ProSe direct communication transmission and may estimate the resources required for transmission.

On the other hand, mode 2 refers to an autonomous resource selection mode by the UE, in which the UE itself is a resource pool in order to transmit direct data and direct control information (ie, SA). Select a resource (time and frequency) from. For example, the contents of SIB18, ie, the field comTxPoolNormalCommon, define at least one resource pool, and these particular resource pools are broadcast within the cell and then for all UEs in the cell that are still in the RRC_Idle state. It is commonly available for. In practice, the eNB can define up to four different instances of this pool (ie, four resource pools for sending SA messages and "direct" data). However, in Release 12, the UE will always use the first resource pool defined in the list, even if it has multiple resource pools configured on it. This constraint has been removed in Release 13 and the UE can send in multiple resource pools out of the configured resource pools within one SC period. Hereinafter, a method of selecting a resource pool for transmission by the UE will be further described (further defined in Non-Patent Document 2).

Instead, the eNB defines another resource pool and signals it at SIB18 (ie, by using the commTxPoolExceptional field), and the UE can use this resource pool in exceptional cases.

Which resource allocation mode the UE uses can be set by the eNB. In addition, which resource allocation mode the UE uses for D2D data communication can also be determined by the RRC state (ie RRC_IDLE or RRC_CONNECTED) and the UE coverage state (ie in or out of coverage). If a UE has a serving cell (ie, the UE is RRC_CONNECTED, or is camping on a particular cell in RRC_IDLE), the UE is considered to be in coverage.

FIG. 4 shows the use of transmit / receive resources in overlay (LTE) and underlay (D2D) systems.

The eNodeB basically controls whether the UE applies the transmission of the mode 1 or the transmission of the mode 2. When the UE recognizes a resource capable of transmitting (or receiving) D2D communication, it uses the corresponding resource only for the corresponding transmission / reception. For example, in FIG. 4, the D2D subframe is used only for the purpose of receiving or transmitting a D2D signal. Since the UE as a D2D device operates in half-duplex mode, it can either receive or transmit a D2D signal at any time point. Similarly, the other subframes shown in FIG. 4 can be used for LTE (overlay) transmission and / or reception.

[Transmission procedure in D2D communication]
Rel. The D2D data transmission procedure according to 12/13 differs depending on the resource allocation mode. As mentioned above, in the case of mode 1, the eNB explicitly schedules the resource for transmitting the scheduling allocation (SA) and the D2D data after the corresponding request from the UE. In particular, the eNB can notify the UE that D2D communication is basically allowed but mode 2 resources (ie, resource pools) are not provided. This notification can be performed, for example, by exchanging a D2D communication interest indication by the UE and a corresponding response, the D2D communication response. In this case, the corresponding exemplary ProseCommConfig information element does not include commTxPoolNormalCommon. That is, a UE wishing to initiate direct communication, including transmission, must request resource allocation from E-UTRAN for each transmission. Therefore, in such cases, the UE must request resources for individual transmissions. Hereinafter, a series of steps of the request / allocation procedure in the case of resource allocation in mode 1 will be exemplified.
-Step 1 The UE sends a scheduling request (SR) to the eNB via the PUCCH.
Step 2 The eNB grants the UL resource (for the UE to send the sidelink BSR) via the PDCCH scrambled by C-RNTI.
-Step 3 The UE sends a D2D / sidelink BSR indicating the buffer state via the PUSCH.
Step 4 The eNB allocates D2D resources (for the UE to send data) via the PDCCH scrambled by D2D-RNTI.
Step 5 The D2D transmitting side UE transmits SA (scheduling allocation) / D2D data according to the grant received in step 4.

Scheduling allocation (SA) (also referred to as SCI (side link control information)) is control information (eg, a pointer indicating a time-frequency resource for transmitting the corresponding D2D data, a modulation / coding method, a group destination ID). A compact (low payload) message containing. The SCI conveys the side link scheduling information of one (ProSe) destination ID. The content of the SA (SCI) basically follows the grant received in step 4 above. The contents of D2D grants and SAs (ie, the contents of SCI) are specifically defined in Section 5.4.3 (incorporated herein by reference) of Non-Patent Document 4, which defines SCI format 0. (See the contents of SCI format 0 above).

On the other hand, in the case of mode 2 resource allocation, steps 1 to 4 above are basically unnecessary, and the UE autonomously allocates radio resources for SA and D2D data transmission from the transmission resource pool set and provided by the eNB. Select.

FIG. 5 schematically illustrates scheduling allocation (SA) and transmission of D2D data for two UEs (UE-1 and UE-2). The resource for transmitting the scheduling allocation is periodic and the resource used for transmitting the D2D data is indicated by the corresponding scheduling allocation (SA).

FIG. 6 illustrates one specific example of mode 2, D2D communication timing for autonomous scheduling during one SA / data period, also known as SC period, side link control period. FIG. 7 illustrates D2D communication timing for mode 1, eNB scheduling allocation during one SA / data period. Rel. In 13, 3GPP defined the SC period as a period consisting of scheduling allocations and transmission of their corresponding data. As can be seen from FIG. 6, after the SA offset time, the UE transmits a scheduling allocation SA_Mode2_Tx_pool using the transmit pool resource to schedule the allocation for mode 2. After the first transmission of SA, the same SA message is retransmitted, for example, three times. The UE then sends D2D data (more specifically, the T-RPT bitmap / pattern) after some configured offset (Mode2data_offset) from the first subframe of the SA resource pool (given by SA_offset). ) Is started. A single D2D data transmission of a MAC PDU (ie, transport block) consists of its first first transmission and several retransmissions. In the illustration of FIG. 6 (and FIG. 7), it is assumed that three retransmissions (ie, second, third, and fourth transmissions of the same MAC PDU) are performed. The mode 2 T-RPT bitmap (transmission time resource pattern (T-RPT)) is basically a MAC PDU transmission (first transmission) and its retransmission (second, third, and fourth transmission). Define the timing of transmission). The SA pattern basically defines the timing of the first transmission of SA and its retransmission (second, third, and fourth transmission).

In one sidelink grant (eg sent by eNB or selected by the UE itself), the UE has multiple transport blocks (MAC PDUs) (subframes (TTIs), as currently specified in the standard). ) Can be sent only once, that is, in sequence), but can be sent to only one ProSe destination group. In addition, the retransmission of one transport block must be completed before the first transmission of the next transport block begins. That is, only one HARQ process is used per sidelink grant to send multiple transport blocks. Furthermore, the UE can have and use several sidelink grants per SC period, but a different ProSe destination is selected for each sidelink grant. Therefore, in one SC period, the UE can transmit to one ProSe destination only once.

As is clear from FIG. 7, in the resource allocation mode (mode 1) scheduled by eNB, the D2D data transmission (more specifically, the T-RPT pattern / bitmap) is the SA in the SA resource pool. It is started in the next UL subframe after the last iteration of transmission. As already described in FIG. 6, the mode 1 T-RPT bitmap (transmission time resource pattern (T-RPT)) is basically a MAC PDU transmission (first transmission) and its retransmission (2). The timing of the 3rd, 3rd, and 4th transmissions) is defined.

The procedure for transmitting sidelink data is described in Section 5.14 (incorporated herein by reference) of Non-Patent Document 2 which is a 3GPP standard. This document details the autonomous resource selection of mode 2 and distinguishes between the case where one radio resource pool or a plurality of radio resource pools are configured.

The above is the current status of the 3GPP standard for D2D communication. However, it should be noted that measures are underway to further improve and enhance D2D communications, and as a result, some changes to D2D communications are likely to be introduced in future releases. The invention described below is also applicable to such future releases.

For example, 3GPP Rel. Currently under development. In the case of 14, 3GPP may change the transmission timing so that it is no longer based on the SC period as discussed above, but differently (eg, based on the same / similar subframe as the Uu interface transmission). Can be decided. Correspondingly, the above detailed example of how transmission over the sidelink (PC5) interface can be performed is merely exemplary. It may be compatible with 13, but probably not with future releases of the corresponding 3GPP standard.

Moreover, in future releases of the D2D framework, T-RPT may no longer be used, especially in relation to vehicle communications.

[ProSe Network Architecture and ProSe Entity]
FIG. 8 illustrates a high level of exemplary architecture for non-roaming, including different ProSe applications in UE A and UE B, as well as ProSe application servers and ProSe functions in the network. The architectural example of FIG. 8 is taken from Section 4.2 "Architectural Reference Model" (incorporated herein by reference) of Non-Patent Document 7.

These functional entities are presented and described in detail in Section 4.4 "Functional Entities" (incorporated herein by reference) of Non-Patent Document 7. The ProSe function is a logical function used for network-related operations required for ProSe, and plays a different role in each of the features of ProSe. The ProSe function is a part of 3GPP's EPC (Evolved Packet Core) and provides all related network services such as authorization, authentication, and data processing related to proximity services. In ProSe direct discovery and direct communication, the UE can obtain unique ProSe UE identification information, other configuration information, and authentication from the ProSe function through the PC3 reference point. Although multiple ProSe functions can be deployed in the network, one ProSe function is shown for ease of explanation. The ProSe function has three main sub-functions that perform different roles depending on the characteristics of the ProSe: the Direct Provision Function (DPF), the Direct Discovery Name Management Function, and the EPC level. It consists of a discovery function (EPC-level Discovery Function). The DPF is used to provide the UE with the necessary parameters for using ProSe direct discovery and ProSe direct communication.

As used in this context, the term "UE" means, for example, a ProSe-enabled UE that supports the following ProSe features:
-Prose control information is exchanged between the ProSe compatible UE and the ProSe function through the PC3 reference point.
-Procedure for open ProSe direct discovery of another ProSe-enabled UE through the PC5 reference point-Procedure for one-to-many ProSe direct communication through the PC5 reference point-To operate as a repeater between the ProSe UE and the network procedure. The remote UE communicates with the repeater between the ProSe UE and the network through the PC5 reference point. Repeaters between the ProSe UE and the network use Layer 3 packet forwarding.
• For example, control information is exchanged between ProSe UEs through the PC5 reference point for repeater detection and ProSe direct discovery between the UE and the network.
-Prose control information is exchanged between another ProSe-compatible UE and the ProSe function through the PC3 reference point. In the case of a repeater between the ProSe UE and the network, the remote UE transmits this control information through the PC5 user plane to be relayed to the ProSe function through the LTE-Uu interface.
-Set parameters (including, for example, IP address, ProSe layer 2 group ID, group security material, and radio resource parameters). These parameters can be preset in the UE or, if within coverage, can be provided to the ProSe function in the network by signaling through the PC3 reference point.

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

[Vehicle communication-V2X service]
To consider the usefulness of new LTE features for the automotive industry, including proximity services (ProSe) and LTE-based broadcast services, Rel. New research items have been set in 14 3GPPs. Therefore, the ProSe function described above is considered to provide an excellent foundation for V2X services. Changes to the D2D framework will be discussed as to how the transmission of vehicle communications can be enhanced. For example, the T-RPT pattern may not be used anymore. Moreover, for the transmission of data and SA, instead of or in addition to using TDD as previously discussed, frequency division multiplexing can be expected. Coordinated services in vehicle scenarios are becoming essential for future connected vehicles within the ITS (Intelligent Transport Systems) research field. These are believed to reduce road accidents, improve road capacity, reduce carbon dioxide emissions in road transport, and improve the user experience on the move.

V2X communication is the transfer of information from a vehicle to any entity that may affect that vehicle and vice versa. This information exchange includes driver-assisted vehicle safety, speed adaptation and warning, emergency response, mobility information, navigation, traffic operations, commercial vehicle group planning and payment transactions, safety, mobility, and Can be used to improve environmental applications.

LTE support for V2X services includes three types of different use cases:
V2V: Covers LTE-based communication between vehicles.
V2P: Covers LTE-based communication between a vehicle and a device carried by an individual (eg, a mobile terminal carried by a pedestrian, cyclist, driver or passenger).
V2I: Covers LTE-based communication between the vehicle and the roadside aircraft.

These three types of V2X may use "co-recognition" to provide more intelligent services for the end user. This is because transmission entities such as vehicles, roadside infrastructure, and pedestrians have knowledge of the local environment (eg, to provide more intelligent services, such as coordinated collision warnings and autonomous driving. , Information received from other vehicles or sensor devices in the vicinity), which means that knowledge can be processed and shared.

When authorization, authentication, and proximity criteria are met for V2V communication, E-UTRAN will allow such (vehicle) UEs in close proximity to each other to use E-UTRA (N) to provide V2V related information. Allows for replacement. The proximity reference can be set by an MNO (Mobile Network Operator). However, UEs that support V2V services may or may not be serviced by E-UTRANs that support V2X services to exchange such information.

A device (vehicle UE) that supports a V2V application transmits application layer information (eg, with respect to its position, dynamic characteristics, and attributes as part of a V2V service). The V2V payload must be flexible to accommodate the different information content, and this information can be transmitted periodically according to the settings provided by the MNO.

V2V is primarily broadcast-based. V2V is an infrastructure that supports V2X services, such as RSUs, application servers, etc., for the direct exchange of V2V related application information between different devices and / or for the limited direct communication range of V2V. Includes the exchange of V2V related application information between different devices via the structure.

For V2I communication, a device that supports a V2I application may send the application layer information to the roadside machine, which in turn may send the application layer information to a group of devices or to a device that supports the V2I application.

If one party is the UE and the other party is the serving entity, both support V2N (Vehicle to Network: Vehicle-Network, eNB / CN) applications and communicate with each other over the LTE network. V2N will also be introduced.

When authorization, authentication and proximity criteria are met for V2P communication, E-UTRAN allows such UEs in close proximity to each other to exchange V2P-related information using E-UTRAN. .. The proximity reference can be set by the MNO. However, UEs that support V2P services may exchange such information even when not serviced by E-UTRANs that support V2X services.

UEs that support V2P applications transmit application layer information. Such information is provided by vehicles with UEs that support V2X services (eg, warnings to pedestrians) and / or by pedestrians with UEs that support V2X services (eg, warnings to vehicles). Can be broadcast.

V2P is a direct exchange of V2P-related application information between separate UEs (one for vehicles and the other for pedestrians) and / or V2P between separate UEs due to the limited direct communication range of V2P. Includes the exchange of relevant application information via an infrastructure that supports V2X services, such as, for example, RSUs, application servers, and so on.

For this new research item, V2X, 3GPP provided specific terms and definitions in Non-Patent Document 8 that could be reused for this application.
Roadside Vehicle (RSU): An entity that supports V2I services that can be sent and received to and from the UE using V2I applications. RSUs can be implemented in eNBs or fixed UEs.
V2I service: A type of V2X service where one party is the UE and the other party is the RSU, both using V2I applications.
V2N Service: A type of V2X service where one party is the UE and the other party is the serving entity, both using V2N applications and communicating with each other over the LTE network entity.
V2P service: A type of V2X service in which both parties of the communication are UEs using the V2P application.
V2V service: A type of V2X service in which both parties of the communication are UEs using the V2V application.
V2X service: A type of communication service that includes a transmit or receive UE that uses a V2V application over a 3GPP transport. Based on the other party involved in the communication, it can be further classified into V2V services, V2I services, V2P services, and V2N services.

Many ITS services have common communication requirements.
-Periodic status exchange. The ITS service usually needs to know the status of the vehicle or roadside terminal. This means the periodic exchange of data packets with information about position, speed, identifier, etc.
-Asynchronous notification. This type of message is used to notify you about a particular service event. Reliable delivery of these messages to a single terminal or their group, as opposed to previous status messages, is usually an important requirement.

Examples of first communication type applications are traffic efficiency services such as remote vehicle monitoring, which collect periodic status data from vehicles, or kinematic information about surrounding vehicles to detect potential impacts. Can be found in safety services such as coordinated collision avoidance that require. Asynchronous notifications can be found primarily in safety services such as slippery pavements and post-collision warnings.

Various types of messages are defined for V2V communication. Two different types of messages have already been defined by ETSI for Intelligent Transport Systems (ITS). See the corresponding European standards ETSI EN 302 637-2 v1.3.1 and ETSI EN 302 637-3 v 1.2.1.
-Cooperative recognition message (CAM). This is continuously triggered by the vehicle dynamics to reflect the status of the vehicle.
-Distributed environment notification message (DENM). This is only triggered when a vehicle-related safety event occurs.

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

The CAM is continuously (periodically) broadcast by the ITS-S to exchange status information with other ITS-stations (ITS-S), and is therefore more than an event-triggered (aperiodic) DENM message. It has a great effect on the traffic load. In essence, a CAM message is a type of heartbeat message that is periodically broadcast by each vehicle to its vicinity to provide information on presence, location, temperature, and basic status. Conversely, the DENM is an event-triggered message broadcast to warn road users of dangerous events. For this reason, the traffic characteristics of CAM messages as defined by ETSI for ITS are considered to be more representative of V2V traffic.

Coordinate recognition messages (CAMs) are messages exchanged between ITS and S in the ITS network to form and maintain mutual awareness and support vehicle coordination performance using the road network. Point-to-multipoint communication is used to transmit the CAM so that the CAM is transmitted from the calling ITS-S to the receiving ITS-S located within the direct communication range of the calling ITS-S. It shall be. The CAM generation shall be triggered and managed by a coordinated recognition basic service that defines the time interval between two consecutive CAM generations. Currently, the upper and lower limits of the transmission interval are 100 ms (ie, 10 Hz CAM generation rate) and 1000 ms (ie, 1 Hz CAM generation rate). The basic idea of ETSI ITS is to send CAM when there is new information to share (eg, new position, new acceleration, or new directional value). Correspondingly, when the vehicle is slowly moving in a constant direction and speed, the CAM displays only the smallest difference, so a high CAM generation rate does not bring any real benefit. The transmission frequency of the CAM of one vehicle varies between 1 Hz and 10 Hz as a function of the vehicle's dynamic characteristics (eg, velocity, acceleration, and orientation). For example, the slower the vehicle moves, the fewer CAMs will be triggered and transmitted. Vehicle speed is a factor that has a great influence on the generation of CAM traffic.

As mentioned above, the periodic cooperative recognition message has been described. However, it should be noted that while some of the above information has already been standardized, other information such as periodicity and message size has not yet been standardized and is based on assumptions. In addition, normalization may change in the future, and therefore the aspects of how CAMs are generated and transmitted may also change.

Mode 1 and / or mode 2 radio resource allocations are assumed as described above for the vehicle UE to have radio resources on the sidelinks to transmit the CAM. For mode 1 radio resource allocation, the eNB allocates resources for SA messages and data for each SA period. However, when there is a large amount of traffic (eg, high frequency periodic traffic), the overhead on the Uu link from the UE to the eNB can be large.

As is clear from the above, for sidelink V2V communication mode 1 (ie, eNB scheduling radio resource allocation), 3GPP agrees that sidelink semi-persistent radio resource allocation is supported by eNBs and UEs. Most V2V traffic is periodic.

It was agreed to support sensing mechanisms along with semi-persistent transmission to support autonomous resource control / selection mechanisms for V2X sidelinks. The UE will indicate in the PSCCH (SA / SCI) that it has data on the selected set of resources that occur periodically until resource selection occurs. This resource reservation information (signaled within the SCI) sends a V2X message for resource selection so that resources already reserved / booked by other UEs are not considered for radio resource selection. It can be used by other UEs intended to do so. This resource reservation / booking procedure is particularly suitable for traffic in which packets arrive at regular intervals, such as CAM messages.

The indication of the radio resource reserved in the scheduling information as described above can be monitored (“sensing”) by other (vehicle) devices. In general, sensing procedures collect information about radio resources and thus allow predictions about future radio resources that may be used in resource allocation procedures to identify a set of resource candidates for transmission. Although few have already been agreed upon by 3GPP, it can be assumed that the sensing process classifies time-frequency resources into the following:
· "Unavailable" resources. Since these resources have already been booked / reserved by another UE, the UE is a resource that is not allowed to transmit.
-"Candidate (or available) resources". These are the resources that the UE can / can perform transmissions.

In addition, 3GPP agreed to also perform energy measurements for sensing procedures, but this agreement did not provide details on how and which energy measurements should be performed. Therefore, energy-based sensing can be understood as the process by which the UE measures the received signal strength in the PSCH radio resource and / or the PSCCH radio resource. Energy-based sensing can essentially help identify short-range to long-range interference.

In addition, it was discussed whether the priority of the data (or the corresponding radio resource reservation) is indicated in the scheduling allocation (SCI) so that it can be used in the resource allocation procedure, but what is the priority? It was not agreed whether it would be used efficiently.

Further topics raised during the discussion are already known from the ETSI standard (see, eg, ETSI EN 302 571 v.2.0.0 and 102 687 v1.1.1) Channel Busy Rate (CBR). It was to use the channel congestion level (ie, on the PC5 interface) for a resource allocation procedure that could be similar to. Again, no details have been discussed in this regard, let alone an agreement on how to use such congestion levels exactly.

Sensing should be feasible in a simple manner so as not to significantly increase the complexity of the UE. It should also be noted that there can be numerous techniques / options for how to implement the sensing algorithm.

Although general consensus has been reached on sensing and resource reservation for V2X transmission over the PC5 interface, implementing these mechanisms in current systems can lead to problems and inefficiencies.

3GPP TS 36.211 V13.1.0, “Physical Channels and Modulation (Release 8)” 3GPP TS 36.321 V13.2.0, “Medium Access Control (MAC) protocol specification” 3GPP TS 36.213 V13.1.1, “Physical layer procedures” 3GPP TS 36.212 V13.1.0, “Multiplexing and channel coding” 3GPP TR 23.713 V13.0.0, “Study on extended architecture support for proximity-based services” 3GPP TS 36.300 V13.3.0, “Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Overall description; Stage 2” 3GPP TS 23.303 V13.2.0, “Proximity-based services (ProSe); Stage 2” 3GPP TR 21.905 V13.0.0

A non-limiting and exemplary embodiment provides an improved UE autonomous radio resource allocation procedure for data transmission over a sidelink interface. Independent claims provide non-limiting and exemplary embodiments. Advantageous embodiments are subject to the dependent claims.

According to the first aspect, a transmitting device for determining radio resources for transmitting data (eg, periodic or aperiodic data of a vehicle) to other devices via a side link interface is provided. To. It is assumed that the transmitting device continuously performs resource sensing procedures to obtain information about future radio resources. According to one example, radio resource sensing at least comprises monitoring scheduling assignments sent by other devices that announce and / or reserve radio resources at a later time. The reserved radio resource may then be excluded from the radio resource selection. Sensing may also be equipped to measure the received signal energy in the radio resource. In the future, other information may be collected during sensing. However, it should be noted that the sensing procedure is not performed in the subframe in which the device performs the transmission, as the receive and transmit operations cannot be performed simultaneously by the device.

At a particular time, the data becomes available for transmission and the device autonomously by the UE to determine the relevant transmission parameters, including the actual frequency-time radio resources used for data transmission. It is assumed that you will start performing the resource allocation procedure. A send window can be defined that starts when the data becomes available. In it, for example, transmission (and possibly retransmission) should be terminated to comply with data delay requirements. The sensing window, on the other hand, can be defined as the period before the data becomes available, during which the sensing operation acquires information about the radio resources in the transmit window. During the radio resource allocation procedure, the vehicle UE autonomously determines transmission parameters and selects radio resources to perform data transmission within the transmission window.

Based on the results of the sensing procedure, the radio resource selection distinguishes between primary and secondary subframes in the transmit window. Here, in at least one subframe in the sensing window corresponding to the secondary subframe, the vehicle UE performed the transmission and therefore the resource sensing procedure could not be performed, so that the secondary subframe has the resource sensing procedure. A subframe in a send window that provides less information than is possible. Conversely, the vehicle UE performed the resource sensing procedure in all corresponding subframes of the sensing window, so the primary subframe is the transmission in which the resource sensing procedure performed by the vehicle UE collects all possible information. A subframe in the window. For example, a resource sensing procedure that is not performed in subframe t of the sensing window will result in a lack of information in future subframes separated by possible cycles of data transmission. Illustratively, assuming a period that is a multiple of 100 ms with a minimum of 100 ms and a maximum of 1000 ms, the subframes t + 100 ms, t + 200 ms, t + 300 ms, ..., And t + 1000 ms are as secondary subframes when in the transmit window of the vehicle UE. Will be considered.

The vehicle UE preferentially selects radio resources from the primary subframe over radio resources from the secondary subframe. In this regard, if there are multiple possible radio resource candidates, the radio resource candidate ranking should be separate between the primary and secondary subframes, and the UE should send the data. The highest ranking candidate to be used shall be selected. Optionally, if the highest ranking candidate could not be used (eg, causing a collision with another UE), the second highest ranking candidate could be used, and so on. Such ranking procedures can be performed in different ways. It is advantageous to use the time delay between the radio resource candidate and the data arrival time, as well as the energy predictions obtained for the radio resource candidate, during the sensing procedure for ranking the candidates. Radio resource candidates that suffer a short time delay are preferred over those that suffer a longer delay. On the other hand, radio resource candidates with low energy prediction values are preferred over those for which the sensing procedure predicts high transmission energy.

It is possible to use measurements across all subframes of the sensing window for energy prediction, but further variants are specific by considering only the subframes associated with the candidate radio resource subframes. Improve energy prediction for radio resource candidates. This association is based on possible periods of data, i.e. -100 ms, -200 ms, -300 ms, ..., -1000 ms, as already discussed above.

According to a further aspect, the radio resource selection and transmission performed by the vehicle UE for scheduling allocation is improved as it was for data transmission. Correspondingly, a radio resource reservation may be made for the transmission of the scheduling allocation, the vehicle UE performs a radio resource sensing procedure, and the result is for the radio resource selection for the scheduling allocation transmission. Can be used. Resource reservations for scheduling allocations can be performed separately or in common with radio resource reservations for data. When performed in common with data resource reservation, the vehicle UE reserves radio resources for both data and scheduling allocations, or does not reserve radio resources for either of them. .. The corresponding indication provides in the scheduling allocation so that the receiving entity learns that the received scheduling allocation also reserves the radio resource for one or more future transmissions of the scheduling allocation and / or data. Can be done.

The radio resource selection procedure performed for scheduled allocation transmission may also be able to distinguish between primary and secondary subframes, as discussed above for data transmission. The corresponding result of the sensing procedure is that the resource sensing procedure has acquired all possible information (resulting in a primary subframe) or all possible information (resulting in a secondary subframe). It is used in the above viewpoint to distinguish subframes in the transmission window that are not acquired. The non-sensing subframe t in the sensing window becomes a secondary subframe at t + 100 ms, t + 200 ms, t + 300 ms, ..., T + 1000 ms. Again, resources from the primary subframe shall be better selected than resources in the secondary subframe to perform the selection procedure for sending scheduling allocations. Candidate ranking procedures within the primary and secondary subframes should be performed separately from each other. The actual ranking procedure for resource candidates for scheduling allocation transmission may be performed in the same manner as previously discussed for ranking resource candidates for data transmission. For example, radio resource candidates that suffer a short time delay are better than those that suffer a longer delay. On the other hand, radio resource candidates with low energy prediction values are more suitable than those for which the sensing procedure predicts high transmission energy.

Correspondingly, in one general first aspect, the techniques disclosed herein are the transmission of data from a transmitting device to one or more receiving devices via a sidelink interface. Provides a transmitting device for determining the radio resources to be used for. The receiver and processor of the transmitting device performs a resource sensing procedure in order to acquire information about the radio resources that the transmitting device can use to transmit data at a later time. After the data is available for transmission, the processor sends the data in the sensing window, based on the information acquired by the resource sensing procedure, before the data is available for transmission. Perform autonomous radio resource allocation to select radio resources in the transmit window that should be used for. Autonomous radio resource allocation comprises selecting radio resources in the primary subframe of the transmit window better than radio resources in the secondary subframe of the transmit window. Secondary subframes in the send window correspond to subframes in the sensing window where the sending device did not perform the resource sensing procedure during that time, and primary subframes in the sending window during which the sending device performed the resource sensing procedure. Corresponds to the subframe in the executed sensing window.

Correspondingly, in one general first aspect, the techniques disclosed herein are the transmission of data from a transmitting device to one or more receiving devices via a sidelink interface. Provides a method for transmitting devices to determine which radio resources should be used for. This method comprises performing a resource sensing procedure by the transmitting device in order to obtain information about the radio resources available for the transmitting device to transmit data at a later point in time. After the data is available for transmission, the transmitting device sends the data in the sensing window, based on the information acquired by the resource sensing procedure, before the data is available for transmission. Perform autonomous radio resource allocation to select radio resources in the transmit window that should be used for. Autonomous radio resource allocation comprises selecting radio resources in the primary subframe of the transmit window better than radio resources in the secondary subframe of the transmit window. Secondary subframes in the send window correspond to subframes in the sensing window where the sending device did not perform the resource sensing procedure during that time, and primary subframes in the sending window during which the sending device performed the resource sensing procedure. Corresponds to the subframe in the executed sensing window.

Correspondingly, in one general first aspect, the techniques disclosed herein transmit scheduling allocations and data to one or more receiving devices via a sidelink interface. Provides a sending device for. The receiver and processor of the transmitting device performs a resource sensing procedure to obtain information about the radio resources available to the transmitting device to transmit the scheduling assignment at a later point in time. After the first data is available for transmission, the processor selects a radio resource in the transmit window for transmitting the first data, and the first data is for transmission. Autonomous radio resources to select radio resources in the transmit window for transmitting the first scheduling assignment, based on the information obtained by the resource sensing procedure during the sensing window before it becomes available. Perform the allocation procedure. The first scheduling allocation comprises information about the selected radio resource in the transmit window to transmit the first data. The transmitter of the transmitting device uses the selected radio resource to transmit the first scheduling assignment and the selected radio resource to transmit the first data. The first scheduling allocation further indicates reserved radio resources available at a later point in time by the transmitting device to transmit the second scheduling allocation for the second data.

Correspondingly, in one general first aspect, the techniques disclosed herein transmit scheduling allocations and data to one or more receiving devices via a sidelink interface. Provides a method for transmitting devices. This method comprises performing a resource sensing procedure to obtain information about the radio resources available by the transmitting device in order to transmit the scheduling assignment at a later point in time. After the first data is available for transmission, this method uses an autonomous radio resource allocation procedure to select the radio resource in the transmit window to transmit the first data. In the transmit window for sending the first scheduling assignment based on the information acquired by the resource sensing procedure during the sensing window, before the first data is available for transmission. It is equipped with the selection of wireless resources. The first scheduling allocation comprises information about the selected radio resource in the transmit window to transmit the first data. The method then comprises using the selected radio resource to send the first scheduling assignment and using the selected radio resource to send the first data. The first scheduling allocation further indicates reserved radio resources available at a later point in time by the transmitting device to transmit the second scheduling allocation for the second data.

Further benefits and advantages of the disclosed embodiments will be apparent from the specification and drawings. These benefits and / or benefits can be provided individually by the various embodiments and features of the content disclosed herein and in the drawings, all to obtain one or more of these benefits and / or benefits. There is no need to provide.

These general and specific embodiments can be performed using a system, method, computer program, or any combination thereof.

Hereinafter, exemplary embodiments will be described in more detail with reference to the accompanying drawings.

An exemplary architecture of a 3GPP LTE system is shown. An exemplary downlink resource grid of subframe downlink slots as defined in 3GPP LTE (Release 8/9) is shown. The method of establishing a layer 2 link through PC5 in ProSe communication is schematically shown. Demonstrates the use of transmit / receive resources in overlay (LTE) and underlay (D2D) systems. It shows the scheduling allocation (SA) and the transmission of D2D data for two UEs. It shows the D2D communication timing in the autonomous scheduling mode 2 of the UE. The D2D communication timing in the scheduling mode 1 scheduled by eNB is shown. An exemplary architectural model of ProSe for non-roaming scenarios is shown. FIG. 5 illustrates frequency-time radio resources in a data resource pool for a vehicle UE divided into a transmit window and a sensing window at a time P when data becomes available for transmission. Illustrating a frequency-time radio resource in a data resource pool for a vehicle UE, according to the exemplary embodiment of the first embodiment, where the subframes of the transmit window are classified as primary or secondary subframes depending on the sensing procedure. It is a figure to do. FIG. 6 is a sequence diagram for UE behavior according to an exemplary embodiment of the first embodiment. Illustrating frequency-time radio resources in a data resource pool for a vehicle UE according to an exemplary embodiment of the first embodiment, in addition to this, improved energy in the detection window for radio resource candidates in the transmit window. It is a figure which illustrates the sensing procedure. FIG. 3 is a sequence diagram for UE behavior according to the exemplary implementation of the first embodiment, further illustrating the preemption procedure to be performed if no resources are found in the primary and secondary subframes. It is a sequence diagram of the preemption procedure as illustrated in FIG. FIG. 6 is a sequence diagram for UE behavior according to an exemplary embodiment of the first embodiment, further illustrating the channel busy rate reduction function. FIG. 3 is a sequence diagram for UE behavior according to an exemplary embodiment of a first embodiment, further illustrating a collision function for detecting possible collisions between SA and data transmission. It is a sequence diagram for UE behavior according to the exemplary embodiment of the second embodiment. A diagram illustrating frequency-time radio resources in a scheduling allocation resource pool for a vehicle UE according to an exemplary implementation of a second embodiment in which transmission subframes are classified as primary or secondary subframes depending on the sensing procedure. Is.

A "mobile station", a "mobile node", a "user terminal" or a "user equipment" is a physical entity within a communication network. A node can have several functional entities. A functional entity means a software module or hardware module that performs a given set of functions and / or provides a given set of functions to another functional entity on a node or network. A node can have one or more interfaces to attach the node to a communication device or communication medium. Nodes can communicate through these interfaces. Similarly, a network entity can have a logical interface that attaches a functional entity to a communication device or communication medium. A network entity can communicate with another functional entity or partner node through a logical interface.

The claims and the term "radio resource" used in this application should be broadly understood to mean physical radio resources (such as time-frequency resources).

The term "direct communication transmission" as used in this application should be broadly understood as a direct (ie, not via a radio base station (eg, eNB)) transmission between two user devices. .. Correspondingly, direct communication transmission is performed through a "direct sidelink connection" and a "direct sidelink connection" is used for a connection established directly between two user devices. Is a term to be used. For example, in 3GPP, the terminology of D2D (device-to-device) communication, ProSe communication, or sidelink communication is used. The terms "direct sidelink connection" and "sidelink interface" shall be understood in a broad sense and in the context of 3GPP may be understood as the PC5 interface described in the Background Techniques section.

The term "ProSe" or its non-abbreviated form "proximity service" as used in this application is used in LTE systems as an application based on proximity and as exemplified in the background art section. Applies in the context of services. In this context, another term such as "D2D" is also used to mean device-to-device communication in proximity services.

The term "mobile mobile terminal for vehicles" as used throughout this application should be understood in the context of work item V2X (Vehicle Communications), each of which is a new 3GPP research item, as explained in the Background Technology section. Correspondingly, the vehicle mobile terminal is specifically mounted on the vehicle (eg, vehicle, commercial truck, motorcycle, etc.) to perform vehicle communication, ie, for example, safety or driver assistance. For the purpose, it shall be widely understood as a mobile terminal that passes information related to the vehicle to other entities (such as vehicles, infrastructure, pedestrians). Optionally, the vehicle mobile terminal may have access to information available in the navigation system (also assumed to be mounted in the vehicle), such as map information.

As used throughout this application, the term "autonomous radio resource allocation" (conversely "radio base station controlled radio resource allocation") is a 3GPP proximity service that allows two modes for resource allocation, ie. Mode 1 in which the radio base station controls the allocation according to this (that is, radio base station controlled radio resource allocation), and mode in which the terminal (or transmitting device) autonomously selects the resource (without the radio base station) accordingly. Can be understood exemplary in the context of 2 (ie, autonomous radio resource allocation).

As explained in the Background Technology section, 3GPP has introduced a new study item for LTE-assisted vehicle communications, which exchanges V2X traffic between various vehicle mobile terminals and other stations. In order to do so, it shall be based on the ProSe procedure. In addition, certain semi-persistent radio resource allocations shall be supported for V2X traffic, especially for autonomous resource allocation modes by the UE (also referred to as mode 2), as well as radio resource reservations. It has been agreed that mechanisms for sensing are supported for the above purposes. However, sensing and radio resource reservation without providing details on how to implement it and how to adapt other mechanisms to ensure efficient and perfect operation. Only a general agreement has been reached.

For example, it remains unclear how accurately the resource sensing mechanism will be implemented. More specifically, it is not clear how energy measurements are calculated and resources are selected based on the sensing mechanism during Mode 2 radio resource allocation.

One possible solution is described below with reference to FIG. 9, which illustrates frequency-time radio resources in a data resource pool of a vehicle UE (generally a transmitting device). As a unit for illustrating the frequency-time radio resource in the figure, a PRB pair (Physical Resource Block pair; 12 subcarriers for one subframe) is adopted. FIG. 9 is an exemplary and simplified illustration for explaining the solution. At time P, the data becomes available for transmission (ie, packet arrival), and the transmission of the data (possibly also the retransmission) is shown as a transmission window and depends on the delay requirement of the data to be transmitted. It is assumed that it should be terminated at time L (eg, 100 ms; L = P + 100 ms). For example, the result of a sensing procedure acquired in a sensing window consisting of 1000 ms prior to packet arrival is by the vehicle UE to select frequency-time radio resources (and possibly other transmit parameters) to transmit the data. It shall be considered for the radio resource allocation procedure to be performed. Illustratively, it is assumed that three (physical) resource block pairs are required for data transmission (according to current standardization, resource blocks should be contiguous).

One piece of information obtained from the sensing procedure is that certain radio resources in the transmit window have already been reserved by other devices and should therefore not be used by the vehicle UE. The corresponding boxes are vertically striped. The remaining radio resource candidates (three consecutive resource block pairs) in the complete transmit window available for the vehicle UE to transmit data are illustrated as framed in FIG. There are a total of six candidates for the transmit window, all of which can be ranked based on, for example, the energy measurements performed during the sensing procedure within the sensing window.

More specifically, it is possible to measure energy (eg, received signal strength) across the sensing window for related radio resource candidates. Illustratively, the corresponding radio resource candidates are assumed to be ranked from 1 to 4 as shown in FIG. 9 based on the energy measurements. Correspondingly, in the sensing window, radio resource candidates 2 having the same corresponding frequency radio resource are ranked equally. The same applies to the two resource candidates 3 in the lower part of the figure. FIG. 9 illustrates the corresponding radio resources of the sensing window with diagonal stripes, and the measured energies are averaged to predict the energy for the radio resource candidate 2. Similarly, FIG. 9 shows that the corresponding frequency-time radio resources in the sensing window used for energy measurements for resource candidate 4 are horizontally striped. Although not illustrated in FIG. 9 for ease of explanation, the corresponding energy measurements and processes are similarly performed on the radio resources in the sensing window corresponding to Candidates 1 and 3. Correspondingly, the vehicle UE is the highest ranked radio resource candidate to be used to transmit data (candidate 1 in this example), for example, the candidate with the lowest energy estimate. Can be selected.

The above provides a possible solution for implementing sensing procedures and corresponding radio resource allocations.

The implementation of that option deals with situations where radio resource candidates are not available (eg, when there are too many radio resources reserved by other devices). Therefore, the vehicle UE may select radio resource candidates that collide with radio resources already reserved by other devices. This procedure can be referred to as "preemption". During the preemption procedure, the vehicle UE randomly selects the appropriate radio resource from the reserved radio resources in the transmit window, or the appropriate reserved radio with a relatively low received signal strength prediction. You may select a resource. Alternatively, the vehicle UE may select the reserved radio resource with the lowest priority if the priority is also indicated for the reserved radio resource.

However, there are some problems related to the solutions presented above. For example, the received signal strength prediction (transmission energy) of a particular radio resource candidate is based on received signal strength measurements obtained with the corresponding frequency radio resource throughout the sensing window, and therefore resource candidates are placed. It does not reflect the actual transmission status in one subframe. Averaging energy measurements across the sensing window for radio resource candidates in one particular subframe means that the transmission of data and scheduling allocations usually occurs periodically, i.e., only in a particular subframe. Do not consider that. In addition, radio resource selection as illustrated above in connection with FIG. 9 is fairly slow, i.e. a transmission opportunity at the end of the transmit window, so that the vehicle UE and the receiving entity have been waiting for data for a long time. It has to wait for data longer. As discussed above, when using priority during the preemption procedure, the preempted UE (ie, the UE of the resource that collides with the selected radio resource candidate) is placed in close proximity to the vehicle UE. Is possible, which causes serious interference between the two "colliding" transmissions.

As described in the Background Techniques section, D2D transmission over the sidelink interface uses half-duplex rather than full-duplex, so simultaneous V2X transmission and reception is not possible. Therefore, in these subframes where the vehicle UE makes transmissions (eg, scheduling allocation and / or data), the vehicle UE does not perform the sensing procedure. It is unclear how these missed sensing opportunities affect the radio resource allocation procedure performed by the vehicle UE.

The present inventor has conceived the following exemplary embodiments for the purpose of alleviating the problems described above.

Specific implementations of the various embodiments are implemented within the broad specification provided by the 3GPP standard, in part described in the Background Techniques section, with particularly important features being described in the following embodiments. Will be added to. The embodiments are advantageously used in mobile communication systems such as, for example, 3GPP LTE-A (Release 10/11/12/13/14, or upcoming releases) communication systems as described in the Background Techniques section above. However, it should be noted that embodiments are not limited to their use in these particular exemplary communication networks.

The following description is not intended to limit the scope of the present disclosure, but should be understood as merely an example of embodiments for a deeper understanding of the present disclosure. Those skilled in the art will recognize that the general principles of the present disclosure set forth in the claims can be applied to various scenarios in a manner not expressly described below. Although some assumptions have been made for illustration purposes, they shall not limit the scope of the following embodiments.

Various embodiments primarily provide radio resource allocation procedures performed by the vehicle UE when transmitting data to one or more receiving devices. Other features (ie, features that are not modified by the various embodiments) may remain exactly the same as those described in the Background Techniques section, or may be modified without affecting the various embodiments. .. This may include, for example, other steps such as how subsequent transmissions of data are performed exactly by the vehicle UE, or how various transmitting devices discover each other.

One exemplary scenario to which various embodiments can be applied is V2X communication as illustrated in the Background Techniques section. Thus, the transmitting and receiving devices can be, for example, a UE in a vehicle, a roadside unit, a "normal" mobile terminal carried by a pedestrian, and the like. Further, the data can be (periodic) vehicle data, such as CAM messages. It shall be continuously exchanged between various vehicle entities, and resource sensing procedures and semi-sustainable resources for that purpose are discussed in 3GPP.

The following exemplary embodiments are described for illustrative purposes in connection with such V2X communication scenarios, but the invention is not limited thereto.

[First Embodiment]
Hereinafter, the first embodiment for solving the above-mentioned (s) problems will be described in detail. Various implementations and variations of the first embodiment will also be described.

As already mentioned above, exemplary, as described in the background art section of the present application, a vehicle UE that is installed in the vehicle and capable of performing vehicle communication based on the D2D framework is assumed. Correspondingly, vehicle data (eg, periodic and aperiodic data) shall be transmitted by the vehicle UE to other entities interested in the data.

The UE supports the mode 2 radio resource allocation and is the required resource pool so that it can primarily execute and autonomously select radio resources for transmitting scheduling information and data over the PC5 (sidelink) interface. It is assumed that it is set properly using.

The periodic data to be transmitted by the vehicle UE is exemplified by the Co-recognition Message (CAM) detailed in the Background Techniques section. As explained in the Background Technology section, it is generally approved by 3GPP that sensing and radio resource reservations should be included in future standard releases in relation to periodic data transmission. In particular, the radio resource reservation on the transmitting side reserves the same resources currently used for one or more later time instances, for example, to send additional packets of periodic data. Allows you to implement a kind of "semi-persistent" radio resource allocation. As a result, it is not necessary for the vehicle UE to perform resource selection / request (mode 1 or mode 2 resource allocation) again at a later time instance in order to be able to transmit periodic data. Radio resource reservations can be performed in different ways and have not yet been determined by 3GPP. For example, radio resource reservations can be made for the next transmit instance, or for a longer period of time (ie, for more transmit instances than immediately following the periodic data). The scheduling information (SCI) transmitted with the sidelink data identifies the radio resource used for transmission and thus allows the receiving entity to properly receive, process / decode the sidelink data. do. Scheduling information further indicates a radio resource reservation, for example, by indicating the time or period of the data so that the receiving entity can determine at what time (eg, a subframe) the radio resource is reserved. Can be used.

The vehicle UE shall also continuously perform radio sensing procedures as described in the Background Technology section in order to obtain information about future radio resources. This information is then used during the Mode 2 radio resource allocation procedure performed by the vehicle UE to select radio resources (and possibly other transmission parameters) to transmit the data (as well as the corresponding scheduling allocation). Can be used. The sensing procedure involves decrypting the scheduling assignments sent by other devices to identify the reserved radio resource. Optionally, the sensing procedure further comprises an energy measurement (eg, received signal strength, RSSI) over the entire frequency resource for data transmission configured for the vehicle UE.

One possible implementation option for the resource sensing procedure is that all UEs have a map with frequency resource predictions over, for example, 100 ms (eg, up to 1 second), starting from the next subframe. be. Next, at the time P when the packet arrives at the buffer in the UE, the UE has already prepared a map (which may be called a transmit window) of all frequency resources from subframes P to L. Here, L basically corresponds to the maximum time span (according to QoS) until the packet is transmitted. Frequency maps can distinguish between unavailable and available radio resources (and perhaps also include information on the predicted energy levels of different radio resources). Other implementations of wireless sensing procedures are equally possible, for example, here the UE does not continually update such future resource maps, but rather the past in the sensing window only when necessary. Predict radio resources from measurements.

In summary, it is assumed that the vehicle UE continuously performs radio resource sensing procedures to obtain information (reservations and / or RSSI predictions, or even other information) about future radio resources. The vehicle UE may further be capable of transmitting periodic (and aperiodic data), and in connection therewith, transmission of data (which may further include determination of other transmission parameters such as MCS etc.). A mode 2 resource allocation procedure (autonomous by the UE) shall be performed to select the radio resource in the transmit window to be used for. Based on the transmit parameters (such as modulation scheme, code rate, etc.), the vehicle UE determines the number of resource blocks required for transmission and then uses this determined number of resource blocks. , Identify possible radio resources for data transmission. Illustratively, it is assumed that only contiguous resource blocks are used for sidelink transmission.

The first embodiment provides an improved radio resource allocation procedure that takes into account the results obtained from previously performed sensing procedures. According to the first embodiment, the radio resources in the transmit window (ie, the radio resources on which the UE can select the appropriate radio resources for transmission) are the radio resources of the primary subframe and the radio resources of the secondary subframe. Distinguished by wireless resources. The secondary subframe of the transmit window shall correspond to the subframe in the sensing window that acquired less information through sensing because the vehicle UE did not perform the resource sensing procedure. Conversely, the transmit window subframe is the primary subframe when the vehicle UE corresponds to the subframe in the sensing window on which the sensing procedure was performed. Therefore, it should be considered that the predictions for the secondary subframe are less accurate than for the primary subframe, and therefore the radio resources from the secondary subframe are selected during the resource allocation procedure. Is not very desirable.

More specifically, simultaneous transmission and reception on the sidelink interface is not supported by the vehicle UE (see Background Technology section), so the vehicle UE performs receive operations simultaneously when performing transmissions within a subframe. Cannot, and therefore cannot perform resource sensing procedures. The resource sensing procedure collects information about future radio resources for use during the radio resource allocation procedure. As currently agreed, sensing procedures include at least monitoring radio resource reservations and possibly performing energy measurements. In future 3GPP releases, other types of information may be obtained during the sensing procedure, and the embodiments presented herein will still be applicable.

Illustratively, it is assumed that the vehicle UE performed the transmission in subframe t and therefore was unable to perform the sensing procedure in that subframe. Therefore, the vehicle UE may have missed the transmission of scheduling allocations (with or without reservations) and / or the transmission of data by one or more other transmission devices.

As is currently standardized, periodic vehicle data (such as a CAM message) has a period that is a multiple of 100 ms (eg, 200 ms, 300 ms, 400 ms, ... the maximum period between two CAM messages. It is transmitted in 1 second and the minimum cycle is 100 ms). Different cycles or additional cycles may be defined in the future and shall be covered by the embodiments presented herein. Radio resource reservations are typically performed on periodic data and are therefore based on the possible periodicity of the periodic data described above.

In subframes where the sensing procedure was not performed, scheduling allocations that may have been missed are possible for periodic data, depending on the periodicity discussed above, some predetermined time distances. It is possible that the radio resource is reserved only in. For brevity, scheduling allocations generally refer to radio resources for data transmission within the same subframe as scheduling allocations, so that radio resource reservations missed in subframe t are, for example, t + 100ms, t + 200ms, t + 300ms. , ..., There is a possibility that the radio resource in the subframe separated by the corresponding data cycle is reserved, such as t + 1000 ms. For the above reasons, vehicle UEs that performed transmissions in subframe t and therefore did not perform sensing procedures in subframe t are all relevant during the possible radio resource allocation procedure (if in the transmission window). Subframes t + 100ms, t + 200ms, t + 300ms, ..., T + 1000ms are considered as secondary subframes.

Similarly, data or SA transmissions missed in subframe t are not sensed by the vehicle UE by the received signal strength measurement. Considering again that periodic data transmissions can only occur at fixed time distances (eg, 100 ms, or 200 ms, or 300 ms, or ..., or 1000 ms), the measurement information for the subframe t. Due to the lack of, the vehicle UE considers that the energy predictions for the subframes t + 100ms, and t + 200ms, and t + 300ms, and ... t + 1000ms are not very accurate.

Thus, the unsensed subframe results in a lack of predictive information about subsequent subframes, and therefore, according to the first embodiment, is the sensing procedure all possible information (eg, radio resources reserved? Considered as a secondary subframe, as opposed to the primary subframe, which obtained (energy measurements for all frequency radio resources in that subframe).

The vehicle UE shall preferentially select the radio resource from the primary subframe over the radio resource from the secondary subframe in the transmit window. In other words, when determining the radio resource for transmitting data, the vehicle UE shall select the radio resource from the secondary subframe only if no radio resource is available from the primary subframe.

In general, the choice of radio resource is based on previous determination of transmission parameters such as modulation scheme and code rate to be used to transmit the data. Therefore, the vehicle UE determines the number of resource blocks required for transmission. In line with the current agreement and discussion in 3GPP, it is assumed that successive resource blocks should be used for sidelink transmission. In the following exemplary illustrations, it is assumed that three consecutive resource blocks are required for the transmission of data. Therefore, each of the resource candidates obtained in this way is illustrated in the following figure. See FIG.

In connection with this procedure, it is also advantageous to rank the radio resource candidates for the primary subframe separately from the radio resource candidates for the secondary subframe. Correspondingly, during the mode 2 resource allocation procedure, the vehicle UE may determine multiple radio resource candidates in the primary subframe and then select the best candidate for transmitting the data. Rank radio resource candidates. Possible radio resource candidates within the secondary subframe are ranked separately. That is, this ranking is performed within the radio resource candidates of only the secondary subframe. During the radio resource allocation procedure, the vehicle UE then selects the highest ranking candidate from the primary subframe and, if not available, the highest ranking candidate from the secondary subframe.

FIG. 10 is a frequency-time resource diagram of a data resource pool, exemplifying the results of sensing and radio resource allocation procedures according to one exemplary embodiment of the first embodiment. FIG. 10 is a suitable radio resource from a data radio resource pool that is generally available for vehicle UEs to perform data transmission over the side link interface, eg, as described in the Background Techniques section. , Frequency time radio resources are disclosed. Correspondingly, sensing procedures (performed within the sensing window) are also performed for these radio resources, for example, radio resources in a data transmission resource pool. For ease of illustration, the associated energy measurements in the sensing window for radio resource candidates in the transmit window, as illustrated in FIG. 9, are omitted from FIG. As will be apparent, the UE transmission in subframe t, as well as the resulting secondary subframe m, are exemplified at t + 600 ms. In the illustration of FIG. 10, it is assumed that the missed sensing opportunity within the subframe t causes only a single secondary subframe m within the transmit window. For example, the transmit window is only 100 ms. Depending on the length of the transmit window, UE transmission in subframe t can result in two or more secondary subframes (ie, t + 600 ms, and t + 700 ms, t + 800 ms, ...). Separate ranking procedures within the radio resource candidates for the primary subframe and within the radio resource candidates for the secondary subframe are also apparent from FIG. Secondary radio resource candidates are surrounded by a dashed line. In particular, if there are four radio resource candidates (ranked from 1 to 4) from the primary subframe and the primary radio resource candidate is not available, then they are ranked from the secondary subframe (ranked from 1 to 2). ) There are two radio resource candidates.

A simplified exemplary sequence diagram illustrating the behavior of a vehicle UE according to one exemplary embodiment of the first embodiment is presented in FIG. Various steps to be performed by the vehicle UE, as generally described above, are depicted in FIG. The resource sensing procedure is described individually to indicate that resource sensing should be performed continuously. Dashed lines from resource sensing procedures for primary and secondary subframes to radio resource candidate search and ranking steps shall be understood as input of information (eg, radio resource reservations and radio resource energy measurements). ..

There are several options for how to perform the radio resource candidate ranking procedure. One possible, unfavorable solution is presented in connection with FIG. 9 above. Alternatively, candidate ranking may be based solely on the time delay between the radio resource candidate and the packet arrival time, i.e., such that a candidate that results in only a short delay is preferred over a candidate that suffers a long delay. Do not consider energy measurements / predictions in ranking. As a modification of the first embodiment, other particularly advantageous ranking procedures are described below. The ranking procedure may be based on energy measurements made during the sensing window as well as the time distance of radio resource candidates from the time the data became available for transmission. By further considering the delays that would result from using the candidates for data transmission, the latency of data transmission would be reduced. At the same time, the resource occupancy likelihood of the radio resource candidate can also be considered by considering past RSSI measurements.

Two characteristics considered for ranking, energy prediction and delay, can be considered in different ways. In particular, if the delay between the radio resource candidate and the packet arrival time can be considered first and there are multiple radio resource candidates with the same time delay, the received signal to rank the candidates with the same delay. Intensity predictions can be used. Resource candidates are ranked, for example, from high to low in descending order of RSSI so that the candidate with the lowest energy prediction value is the highest ranking candidate for that subframe. Conversely, if the received signal strength prediction is considered first and then there are multiple radio resource candidates with the same received signal strength prediction, a time delay can be used for ranking, here more. Short time delays are ranked higher than longer time delays. According to a further alternative, functions of delay and received signal strength prediction can be used to rank radio resource candidates. An exemplary function can be Z _i = X * T _i + Y * RSSI _i . X and Y are weights given to the time delay and the received signal strength characteristic, respectively. Ti indicates the time distance between the radio resource candidate _i and the packet arrival time. RSSI _i indicates a predicted value for the received signal strength of the radio resource candidate i (based on previous measurements in the sensing window). The smaller the value Z _i , the higher the rank of the resource candidate i. The weights X and Y can be set, for example, by the eNB, or else can be predetermined.

The results of an exemplary ranking procedure that primarily considers time delays as described above are illustrated in FIG. As will be apparent, the highest ranked (ranking value 1) primary radio resource candidate is the radio resource candidate within the primary subframe that has the least delay with respect to the packet arrival time. The remaining radio resource candidates in the primary subframe are also ranked based on the time distance to the packet arrival time. On the other hand, the secondary subframe m ranking procedure needs to further depend on the energy measurements performed during the sensing window to distinguish between the two radio resource candidates. An exemplary ranking is illustrated in FIG.

A more advantageous variant of the first embodiment improves the prediction of received energy levels for radio resource candidates. As described in connection with FIG. 9, one possible option is the radio corresponding to the radio resource of the particular radio resource candidate across all sensing windows in order to predict the received signal strength of the particular radio resource candidate. It is to use the energy readings in the resource. However, this has the disadvantage that it may not reflect the actual transmission status of this one subframe of radio resource candidates. To improve transmission energy prediction, only relevant subframes should be considered for prediction. More specifically, the relevant subframes within the sensing window are those having a possible data period time distance with respect to the radio resource candidates to be ranked. As currently assumed for data transmission, the data period is a multiple of 100 ms (minimum 100 ms and maximum 1000 ms). As a result, with respect to the improved energy prediction for a particular subframe m in the transmit window, the relevant subframes in the sensing window are m-100 ms, m-200 ms, m-300 ms, m-400 ms ..., and m. -1000 ms. Only energy measurements made in those associated subframes of the sensing window are used to predict the energy in the subframe m of the transmit window.

FIG. 12 illustrates this improved transmit energy prediction based on the assumptions already adopted for FIG. 10 and distinguishes between the six radio resource candidates determined for the primary and secondary subframes. As is clear from this, FIG. 12 shows energy measurements for the primary radio resource candidate 1 in subframe u at the corresponding radio resources in subframes u-600 ms and u-1000 ms. Energy measurements in the remaining relevant subframes of the sensing window, ie u-100ms, u-200ms, ..., U-500ms, u-700ms, u-800ms, u-900ms, are also for ease of illustration. , They are not shown in FIG. 12, but are considered. Similarly, energy measurements at different radio resources in related subframes are used, but both radio resource candidates for the secondary subframe m are subframes m-100s, m-200ms, ..., M in the sensing window. -Related to 1000 ms. Correspondingly, FIG. 12 marks the relevant radio resources within the subframe m-1000 ms used for energy prediction. It should be noted that energy measurements in subframe m-600 ms radio resources were not possible due to the transmission performed by the vehicle UE. As previously discussed, possible periodic transmissions with a period of 600ms that have an effect on the subframe m of the transmission window will not be sensed. This is one of the reasons for classifying the subframe m as merely secondary to the radio resource allocation procedure. The received signal strength (ie, energy) measured in the radio resources of the relevant subframes can be averaged, for example, to obtain predictions of radio resource candidates in the subframes of the transmit window.

The advantage of this is that the improved energy prediction is more accurate because it takes into account the possible cycles of data transmission.

Another advantageous embodiment of the first embodiment provides a solution when no suitable radio resource is found in either the primary subframe or the secondary subframe. As discussed earlier, preemption procedures allow you to select a radio resource from among the radio resources in the transmit window, even when they are already reserved by other transmit devices.

FIG. 13 is based on the diagram of FIG. 11 as a step when the vehicle UE is unable to discover the resources in the secondary subframe (also after failing to discover the resources in the primary subframe). , Is an exemplary sequence diagram of UE behavior extended using preemption procedures. As is apparent from FIG. 13, after determining the radio resource during the preemption procedure, the vehicle UE determines the corresponding radio resource for scheduling allocation and then transmits both SA and data. In addition, the preemption box receives information as input from the resource sensing procedure, such as energy measurements for radio resources, radio resource reservations made by other devices, and possibly information regarding radio resource reservation priorities. The latter information is such that priority information (such as PPPP, ProSe-Per-Packet-Priority: Priority per ProSe packet) is transmitted with the radio resource reservation and is therefore decoded and stored by the vehicle UE during the sensing procedure. Need to be.

FIG. 14 is a simplified exemplary preemption procedure that can be performed by the vehicle UE when radio resources are not available and should be seen as one possible implementation of the preemption procedure illustrated in FIG. It is a sequence diagram. An option check that should be performed at the beginning of the preemption procedure is whether the data to be sent can be discarded (ie, discarded so that it is not sent). In one embodiment, the vehicle UE determines whether or not the data should be discarded based on the priority of the data. The priority of this data can be compared with the appropriate priority threshold. Data is typically associated with a ProSe packet-by-ProSe packet priority (PPPP) that indicates the priority of the data. Appropriate priority thresholds may be defined in the vehicle UE, for example by eNodeB. It is then used to distinguish between data that can be discarded and data that cannot. If the priority is not high enough (eg, below the priority threshold), the data will be discarded. If not, the preemption procedure now proceeds to select the radio resources that should be used to send the data, however, in addition to this, the previous candidates in the primary and secondary subframes. It also takes into account reserved radio resources that were initially excluded from the search. As mentioned above, data destruction is an optional check performed by the vehicle UE and may therefore be configurable, for example, by the eNB or by a higher layer of the vehicle UE.

Although illustrated as part of the preemption procedure, the discard check can be performed outside the actual preemption procedure, so that the preemption procedure (without the discard check) is performed only when the packet is not dropped. To.

In addition, the decision on whether to discard the data may be made by a higher layer of the vehicle UE (such as the RRC or application layer).

Preemption refers to the process of selecting and using radio resources already reserved by other transmitting devices to transmit data. Therefore, some reserved radio resources are "overwritten" by their own transmission, which can cause serious interference and should be avoided if possible. Is. Nevertheless, if the data is significant enough, the vehicle UE may, in part or in whole, select one or more radio resource candidates with the appropriate resource block size, with reserved radio resources. You should decide. If there are multiple resource candidates available, the vehicle UE needs to determine the most appropriate candidate. One possible option, as already discussed earlier, is to perform a random selection of candidates across the send window, or preferably within the primary subframe, and then within the secondary subframe. ..

According to an advantageous implementation of the first embodiment, the selection of radio resource candidates during the preemption procedure takes into account the radio resource priority and / or the RSSI prediction value determined during the sensing procedure within the sensing window. By doing so, it will be improved to mitigate any problems caused by preemption. In one example, the vehicle UE performs preemption by selecting the radio resource candidate with the lowest priority among the reserved radio resources. Then, if several candidates with the same priority remain, the vehicle UE may select the candidate with the lowest RSSI prediction value. In the second example, the vehicle UE selects the radio resource candidate with the lowest RSSI prediction level, and if some candidates remain, the candidate with the radio resource with the lowest priority selects the data. Selected for sending. Alternatively, the function may be defined based on two separately weighted parameters: reservation priority and RSSI. An exemplary function can be Z _i = w1 * 1 / P _i + w2 * RSSI _i . w1 and w2 are weights given to the priority (the lowest priority value is the highest priority) and the received signal strength characteristic, respectively. P _i represents the priority given to the specific radio resource reservation as a part of the resource candidate i, and RSSI _i shows the predicted value of the received signal strength of the radio resource candidate i. The vehicle UE shall select a radio resource candidate with a small (minimum) _Zi value.

Optionally, the priority of the reservation can be compared to the priority of the data so that only the reserved radio resource is preempted with a lower priority than the data to be transmitted. Alternatively, it may be possible to define the corresponding priority and energy thresholds so that the radio resource selection can be limited to only the "optimal" radio resources below both thresholds. Radio resources that exceed the threshold are excluded. As an option, the preemption procedure can also distinguish between primary and secondary subframes, after which candidates are preferred to be selected from the primary subframes rather than the candidates within the secondary subframes.

In addition to, or instead, the preemption procedure should preferably determine radio resource candidates for the transmission of data that invalidate the minimum amount of reserved radio resources. In particular, considering that only a set of contiguous resource blocks is used for sending data over the sidelink, a few reserved resource blocks are used to get a set of resource blocks large enough to send the data. Preemption is enough. As a result, interference with other transmitting UEs is reduced.

As a further possible criterion for the preemption procedure, to minimize the number of other devices that may be affected by preemption, or so that each device is not significantly affected by preemption while it can still decode the data. Reserved radio resources may be selected to maximize the number of other devices.

If some candidates remain after considering two or three parameters (reservation priority, data priority, or RSSI) according to any of the above examples, the vehicle UE is the remaining radio resource candidate. One of them can be randomly selected.

By considering the energy predictions for the preemption procedure, strong interference between the data transmission performed by the vehicle UE and the preemption data transmission of the nearby vehicle UE should be avoided.

Thus, after determining the appropriate radio resource for transmission of data, the vehicle UE selects the resource for transmitting the scheduling allocation, as illustrated in FIG. 13, and then the scheduling allocation and data. Send both.

According to a more advantageous embodiment of the first embodiment, the congestion level of the side link channel is taken into account for the radio resource allocation procedure performed in the vehicle UE. The congestion level of a sidelink channel (channel busy rate, also known as CBR) is, for example, comparing the energy level of a sufficient sample to the threshold over the entire bandwidth or only within one resource pool. Determined by the vehicle UE. For example, if 90% of the samples have energy levels above the threshold, the CBR is 90%. The threshold can be fixed, set, or preset by the eNB. CBR is a measure of the busy level of a carrier or resource pool. The CBR can be used by the vehicle UE to determine whether to discard the data, taking into account the channel state. In general, this CBR check is optional and can be set, for example, by eNodeB or (eg, by the operator), thereby whether or not the CBR check should be performed and how. Set the UE as to what should be done. For example, if the eNodeB is conservative and you want to protect the sidelink carriers, you may configure some or all UEs in the cell to perform such a CBR check (eg, by system information broadcast). On the other hand, if the eNodeB is interested in achieving higher throughput, the eNodeB may configure the UE not to perform this CBR check. One possible practice of CBR checking is to prioritize the data to be transmitted and compare it to the priority threshold. The priority threshold can optionally depend on the CBR detected for the sidelink channel. For example, the procedure proceeds only if the data to be transmitted has a sufficiently high priority, despite the high congestion level of the channel. On the other hand, low priority data can be discarded in consideration of busy channels.

The traffic type of data to be transmitted may also be taken into account in the CBR discard function in addition to, or instead of, the priority of the data. For example, different thresholds can be defined for safe traffic and non-safety traffic. Assuming priority levels from 1 to 5, where the higher the number, the lower the priority. For a 90% CBR, priority level 5 secure traffic and priority levels 5, 4, and 3 unsafe traffic should be discarded. On the other hand, when the CBR is 80%, safe traffic is not discarded, but only unsafe traffic of priority level 5 is discarded. When the CBR is 70%, safe traffic is not dropped, priority level 5 or 4 unsafe traffic is dropped, and so on.

If the data is discarded, the responsible higher layer is notified of the failure to send the data so that, for example, the higher layer decides to send the data again later, or even in the higher layer. Can be discarded to notify the user of the failed transmission.

FIG. 15 is an exemplary sequence diagram based on the diagram of FIG. 11 and extended with CBR checks as discussed above. In particular, after the data is available for transmission, the vehicle UE may decide whether to discard the data by considering the channel busy rate. If the vehicle UE decides not to discard the data, the procedure known from FIG. 11 and described in detail above is then continued.

The CBR check can be considered as either part of the resource allocation procedure or a pre-resource allocation step to determine if resource allocation should be initiated.

Further, the radio resource sensing procedure can be performed for each radio resource pool configured in the vehicle UE for mode 2 resource allocation. In the above case, whether or not the vehicle UE uses the CBR check and how to use it can be set for each resource pool. For example, during the configuration of the data resource pool, the eNodeB may indicate whether or not the CBR check should be performed and how it should be performed. For out-of-coverage UEs and corresponding radio resource pools, the CBR configuration may be part of the presetting for each resource pool.

A more advantageous implementation of the first embodiment provides a collision check to determine if each scheduling allocation and the planned transmission of data conflicts with another UE's data transmission. .. FIG. 16 is an exemplary sequence diagram based on the diagram of FIG. 11 and extended with one implementation of collision checking as discussed below. As is apparent from FIG. 16, after selecting the appropriate resource for scheduling allocation and data transmission, the vehicle UE continues to perform the sensing procedure and therefore monitors the scheduling allocation transmitted by other UEs. Perhaps make a resource reservation for the future. Based on the scheduling allocations received from the other UEs, the vehicle UE will collide with the transmissions announced by the other UEs as indicated by the monitored scheduling allocations. Can be checked. In the event of a collision, the vehicle UE can determine how to proceed further, eg, prioritize the two conflicting transmissions, namely the SA transmission itself and the transmission of the other UE. Can be compared. If its SA transmission has a higher priority, the vehicle UE continues to transmit the scheduling allocation as already planned. In other cases, the vehicle UE may return to the first step of the radio resource allocation procedure to determine new radio resources for scheduling allocation and, if necessary, data transmission. Alternatively, in the case of a collision, the SA and data are discarded, especially when their SA transmission has a lower priority.

Collision detection works similarly for data transmission. It is assumed that a scheduling assignment for data transmission has been sent. The sensing procedure is continuously performed by the vehicle UE until the time of data transmission, and thus possible data transmissions by other devices that collide with their own data transmissions may be detected. In such a collision, the vehicle UE may, for example, compare the priorities of two data transmissions. If its own data transmission has a higher priority, the vehicle UE continues to transmit the data as previously planned. In other cases, the vehicle UE may need to return to the first step of the radio resource allocation procedure to determine new radio resources for data and SA transmission. Alternatively, in the case of a collision, the data is discarded, especially when its own data transmission has a low priority.

In the above, different embodiments of the first embodiment have been described. Here, a "basic" implementation is described in relation to FIG. 11, and extensions to the "basic" implementation are described in FIGS. 13, 14, 15, and 16, respectively. Although this extension is described and illustrated separately, some or all of them can be combined to form complete UE behavior, which is the preemption procedure of FIG. 13 and / or FIG. It has a CBR discard function and / or a collision check as shown in FIG.

In the above, it was assumed that the vehicle UE always uses the results of the sensing procedure for autonomous resource allocation by the UE (mode 2). However, whether or not to use sensing for resource allocation and how to use it can instead be configurable and / or the vehicle UE selects radio resources for transmission. It may depend on the wireless resource pool you have. More specifically, in one implementation, the eNodeB responsible for the vehicle UE controls whether and how the sensing procedure should affect radio resource allocation. For example, eNodeB broadcasts the corresponding configuration in the cell, whether or not all vehicle UEs in the cell receiving the configuration use sensing for autonomous resource allocation by the UE, and how. Learn to use for. Alternatively, a dedicated message from the radio base station to only these vehicle UEs to control whether and how the sensing procedure should be performed in one or more vehicle UEs. Is sent.

[Second Embodiment]
In the following, a second embodiment that can be used in combination with various embodiments of the first embodiment is described. In connection with the first embodiment, it was simply assumed that the vehicle UE selects the resource for transmitting the scheduling allocation without elaborating on how the vehicle UE actually makes the resource selection. .. As explained in the Background Technology section, the selection of resources for sending scheduling allocations is well defined in previous releases of 3GPP. In short, in the case of autonomous radio resource allocation by the UE (mode 2), the vehicle UE randomly selects a radio resource from the corresponding scheduling allocation resource pool and further repeats this scheduling allocation in the T-RPT pattern. Can be selected. However, 3GPP discusses and agrees to implement improvements for resource selection for data transmission (a radio resource reservation mechanism and sensing procedure have been introduced as discussed above), while scheduling allocation. There is no discussion or agreement on how the transmission will be improved in future releases. One motivation for the agreed improvements regarding V2X data transmission is to increase the reliability of such transmissions, which is a pure random selection of radio resources for data transmission (eg, with respect to collision rate). May not be guaranteed. For example, the number of vehicle UEs is expected to increase in the future, and a random resource selection mechanism for sending scheduling allocations can lead to an increase in the number of collision failures. However, robust transmission of scheduling allocations, especially in a vehicle communication environment, is just as important as reliable transmission of data.

Therefore, the second embodiment provides an improved UE-based autonomous radio resource allocation procedure for selecting radio resources for scheduling allocation transmission. The transmission of scheduling assignments is modified to mimic the expected improvements for data transmission, as discussed for the first embodiment. Correspondingly, the implementation of the second embodiment is performed by the vehicle UE for the radio resources of one or more SA resource pools available by the transmitting device to transmit the scheduling allocation. Provides resource sensing procedures. It is noted that the radio resource sensing procedure as described in the first embodiment probably senses different radio resources, i.e., radio resources in a data resource pool available by the transmitting device to transmit data. Should be. However, the radio resources in the scheduling allocation resource pool and the radio resources in the data resource pool can overlap. In any case, in a manner similar to that described in detail in the first embodiment, the vehicle UE will continue to perform sensing procedures on those radio resources to provide information about future scheduling allocation radio resources. Shall be acquired.

As described in more detail in the following embodiments of the second embodiment, the radio resource reservation is not only for the transmission of data as described in the first embodiment, but also for the transmission of scheduling allocations. It shall also be implemented. Scheduling allocations and radio resource reservations for data can be similar. In short, by providing the appropriate indications in the scheduling allocation, the radio resource used for the transmission of the current scheduling allocation may be reserved for future scheduled assignment transmissions.

By monitoring the scheduling allocation transmitted by other devices, the resource sensing procedure also determines whether the radio resource is reserved by another transmitting device for transmission of the scheduling allocation, and which radio resource. It shall be possible for the vehicle UE to obtain information as to whether or not the vehicle is reserved. These reserved radio resources may be excluded from the radio resource allocation procedure performed by the vehicle UE in order to select the radio resource for transmitting the scheduling allocation. The radiosensing procedure may also include energy measurements (eg, received signal strength, RSSI) across frequency resources configured for transmission of scheduling assignments. In the future, other types of information may be collected as well. Therefore, the sensing procedure collects information about future radio resources that should be used to send scheduling assignments. It can be used during the resource allocation procedure to select the best radio resource for sending the scheduling allocation.

It is assumed that the vehicle UE transmits periodic data and performs an autonomous radio resource allocation procedure by the UE to determine resources for transmitting scheduling allocation and pending data.

As already discussed in detail in connection with the first embodiment, the radio resource allocation procedure includes the radio resource of the primary subframe and the radio resource of the secondary subframe in consideration of the result obtained from the sensing procedure. Can be improved by distinguishing between. The secondary subframe of the transmit window shall correspond to the subframe in the sensing window. Here, the vehicle UE does not always perform the resource sensing procedure. Therefore, the vehicle UE always performs the sensing procedure and acquires less information by sensing compared to the primary subframe corresponding to the subframe in the sensing window, which acquires all possible information. Therefore, as described in detail with respect to the first embodiment, the vehicle UE misses the reservation of the scheduled allocation transmission by another UE in the secondary subframe, or affects the energy prediction of the secondary subframe. Missing energy measurements.

Therefore, predictions for secondary subframes are less accurate than predictions for primary subframes, and radio resources from secondary subframes should not be better selected than radio resources from primary subframes.

As a result, this improvement in the resource allocation procedure presented in detail for the first embodiment in relation to the selection of radio resources for data transmission, according to the second embodiment, for the transmission of scheduling allocations. Can be applied to radio resource selection.

FIG. 17 is a sequence diagram illustrating exemplary and simplified UE behavior according to the embodiment of the second embodiment, similar to FIG. 11 of the first embodiment. As will be apparent, the selection of radio resources for transmitting scheduling assignments is divided into a search in the primary subframe and a subsequent search in the secondary subframe. In particular, after the data is available for transmission, the vehicle UE shall suitably select the radio resource for SA transmission from the primary subframe within the transmission window and for SA transmission. If the radio resource is not available from the primary subframe, the vehicle UE shall search for the radio resource for SA transmission within the secondary subframe. The procedure then continues to send scheduling allocations and subsequent pending data.

FIG. 18 illustrates a frequency-time radio resource for a scheduling allocation resource pool, the resource being available to the vehicle UE to transmit the scheduling allocation. In a manner similar to that made in FIG. 10, FIG. 18 shows how the primary and secondary subframes are defined in the transmit window as a result of unexecuted sensing procedures in one subframe of the sensing window. Illustrate if it is. Also, with respect to the transmission of scheduling allocations, the vehicle UE must first determine the appropriate transmission parameters and therefore the number of resource blocks required for SA transmission. As currently agreed, two physical resource block pairs shall be used for the transmission of scheduling allocations. The vehicle UE then determines possible radio resource candidates that will be available for transmission of scheduling assignments, and exemplary results of the candidate search are illustrated in FIG.

The radio resource candidates for the primary subframe shall be ranked separately from the radio resource candidates from the secondary subframe, for example, in the same or similar manner as discussed for the first embodiment. This is also illustrated in FIG. 18, which illustrates four primary SA radio resource candidates and two separate secondary SA radio resource candidates. In particular, various different implementations of the ranking procedure as discussed for the transmission of data according to the first embodiment are also reused to rank the radio resource candidates that can be used to transmit the scheduling allocation. obtain. For example, the rankings discussed in connection with FIG. 9 are possible but disadvantageous. Alternatively, candidate ranking may be between radio resource candidates and packet arrival times, especially considering that the scheduling allocation must be sent earlier (or in the same subframe) as a data transmission. Obtained based solely on time delay. Another option for candidate ranking is related to the first embodiment, taking into account both the time delay and energy prediction for radio resource candidates, based on the energy measurements performed during the sensing procedure. A variety of different embodiments are presented above and can be reused herein for embodiments of the second embodiment.

As described in connection with FIG. 12, a particularly advantageous embodiment of the first embodiment improves energy prediction. These improved energy measurements and predictions can also be applied to resource sensing detection procedures performed by the vehicle UE with respect to the radio resources available to transmit scheduling assignments. Correspondingly, the energy prediction for a specific resource candidate within the subframe m is a subframe related to the resource candidate subframe, that is, a possible period of m-100 ms, m-200 ms, m-300 ms. ..., Measurements in the sensing window of only subframes separated by m-1000 ms shall be considered.

As illustrated in FIG. 17, a preemption procedure can be predicted during a resource allocation procedure in case no suitable radio resource is found in the primary and secondary subframes. Radio resources reserved by other UEs for transmission of scheduling allocations are preempted by the vehicle UE so that they can still transmit scheduling allocations, in a manner similar to that discussed in detail in the first embodiment. Can be done. In addition, the preemption procedure may comprise a decision as to whether the scheduling assignment should be discarded, which decision can be based on the priority of the data to which the scheduling assignment is sent, which is appropriate. It may be compared with a priority threshold. If the data, here the scheduling allocation, has sufficient priority, the vehicle UE proceeds to determine resource candidates for transmission of the scheduling allocation, which in turn also considers the reserved radio resource. Various advantageous embodiments of the preemption procedure have been discussed in detail in connection with the first embodiment and may be reused to improve the selection of radio resource candidates for the transmission of scheduling allocations. For example, reserved radio resource priorities and / or RSSI predictions determined during the sensing procedure in the sensing window may be taken into account. In addition, the priority of the reserved radio resource may be compared to the priority of the data to be transmitted. Further, the preemption procedure can distinguish between the primary subframe and the secondary subframe, and preferably selects a radio resource candidate from the primary subframe.

In summary, the vehicle UE selects the best radio resource to send the scheduling assignment. As discussed above, the vehicle UE shall also reserve radio resources for the next transmission of scheduling assignments.

In some embodiments of the second embodiment, it may be configurable whether the vehicle UE applies semi-persistent scheduling (eg, radio resource reservation and sensing procedures) to the transmission of scheduling assignments. According to one exemplary practice, the eNodeB controlling the vehicle UE further reserves radio resources for future transmission of scheduling allocations and is based on the results of sensing procedures on the radio resources of the corresponding SA resource pool. By performing a radio resource selection, some or all UEs in the cell may decide whether to improve the scheduled allocation transmission. The eNodeB may then notify the vehicle UE accordingly. For example, if all UEs in a cell of eNodeB are configured in the same way, eNodeB broadcasts a system information message in that cell, and all UEs receiving the broadcast message send SA as instructed. Set the procedure.

On the other hand, how the scheduling allocation is transmitted can be coupled to the transmission procedure followed by the vehicle UE when transmitting the data. As a result, if the vehicle UE applies semi-persistent scheduling to data transmission, it shall also apply semi-persistent scheduling to the corresponding SA transmissions for the sensing procedure. If the UE does not use semi-persistent scheduling, sending scheduling assignments is described in the art, for example, by randomly selecting radio resources from the appropriate SA radio resource pool without reference to the results of the sensing procedure. It can be treated in the same way as it was done.

Instead of or in addition to sending a broadcast message within the cell, the eNodeB may send a dedicated message to the selected vehicle UE. Therefore, these UEs set themselves according to the instructions in the dedicated message. Thereby, the eNodeB may selectively configure the vehicle UE to perform semi-persistent scheduling to send scheduling assignments.

The setting of whether or not to perform the scheduling allocation transmission and how to perform it can also depend on the particular SA resource pool, and therefore, like the sensing procedure, semi-persistent scheduling is also specific. Executed when selecting a radio resource for sending a scheduling assignment from the configured radio resource pool. The corresponding indications when initially configuring the radio resource pool can be sufficient, for example 1 bit for data and 1 bit for SA transmission.

As described below, in a second embodiment, whether the device receiving the scheduling assignment also reserves a radio resource for transmission of one or more future scheduling assignments received. Provides some implementation on how to estimate. One option is to provide a corresponding field (eg, 1 bit) in the scheduling allocation, where the 1-bit value is the radio resource for which the scheduling allocation sends one or more future scheduling allocations. Indicates that (eg, these radio resources used for transmission of the current scheduling assignment) are reserved. Conversely, the other bit values in the scheduling allocation field are understood by the receiving entity as indicating that no radio resource reservation has been made for the scheduling allocation transmission. Alternatively, instead of providing a separate field for the reservation of radio resources for scheduling allocation, another implementation of the second embodiment, for example, radio resource reservations are performed for data transmission. It is based on an implicit indication, such as using the corresponding field of the scheduling assignment to indicate whether or not. Therefore, the scheduling allocation indicates that as long as the data resource is reserved, the corresponding scheduling allocation resource is also reserved. For example, the scheduling allocation may probably include a "periodicity" field indicating the periodicity of the radio resource reservation, the number of instances of the reservation, and the like. No radio reservation (for data transmission as well as SA transmission) is indicated, for example, by including the value 0 in this periodic field.

In the above embodiment of the second embodiment, the retransmission to be performed for scheduling allocation has not yet been considered. Nevertheless, in order to increase the robustness of the scheduling allocation transmission, one or more retransmissions of the scheduling allocation should be performed by the vehicle UE via the sidelink interface. In the above association, in one exemplary practice, a fixed number of (re) transmissions may be preset. As in the prior art, the vehicle UE may send a retransmission of the scheduling assignment in a fixed time relationship with respect to the first transmission of the scheduling assignment. Alternatively, another association between the initial transmission and retransmission of the scheduling allocation may be agreed between the vehicle UE and the possible receiving entity. According to yet another solution, the vehicle UE may also randomly select radio resources for the retransmission of scheduling allocations, as is done for the first transmission. For example, the radio resources available for transmission of scheduling quotas can be further divided into resources for initial transmission and resources for further retransmission of scheduling quotas.

However, randomly selecting radio resources for retransmitting allocations can be problematic. In particular, scheduling allocations are sent using specific radio resources within a set of radio resources, and potential receiving entities detect scheduling allocations by blind decoding within the radio resource set (also known as the radio resource search space). do. In a prior art procedure, the retransmission of a scheduling assignment is one of the specific scheduling assignments that the receiving entity has (for example, in order to properly perform soft combining to successfully decrypt the scheduling assignment). It is executed in a fixed time relationship with respect to the first transmission of the scheduling allocation so that it can know if the (re) transmissions belong together. However, such a fixed time relationship can no longer be guaranteed by performing random resource selections for the retransmission of scheduling allocations as well.

Therefore, it is necessary to provide a new mechanism that allows the receiving entity to associate all transmissions and retransmissions for one particular scheduling assignment. According to one exemplary embodiment of the second embodiment, a common identifier may be included in the scheduling assignment transmission to correlate them together. Correspondingly, a receiving device that receives various transmissions for one particular scheduling assignment may then associate the correct transmission of the scheduling assignment based on a common identifier. According to one example, the common identifier can be a source identifier that identifies both the vehicle UE as the source of transmission and / or the current application that produces the data for which the scheduling allocation is transmitted. The common identifier can be part of a scheduling assignment or can be encoded into a Layer 1 identifier or part of a CRC check.

A further implementation of the second embodiment is to retransmit the scheduling allocation by base the resource selection on the result of the sensing procedure (eg, in the same manner as the first transmission of the scheduling allocation discussed above). Improve your radio resource selection. As already discussed above for the random selection of radio resources for SA transmission, when improving the radio resource selection based on sensing results, the fixed time relationship between initial transmission and retransmission is , Can no longer be guaranteed. Therefore, it is necessary to provide a new mechanism that allows the receiving entity to associate all transmissions and retransmissions for one particular scheduling assignment. According to one exemplary embodiment of the second embodiment, common identifiers as already described above may be included in the scheduling allocation transmission to correlate them together. According to one example, the common identifier can be a source identifier that identifies both the vehicle UE as the source of transmission and / or the current application that produces the data for which the scheduling allocation is transmitted. The common identifier can be part of a scheduling assignment or can be encoded as part of a Layer 1 identifier.

[Implementation of this Disclosure by Hardware and Software]
Another exemplary embodiment relates to implementing the various embodiments described above using hardware, software, or software associated with hardware. In this regard, a user terminal (mobile terminal) is provided. The User Terminal is configured to perform the methods described herein and includes the corresponding entities (receivers, transmitters, processors, etc.) appropriately involved in these methods.

Various embodiments are further recognized as being able to be implemented or performed using a computing device (processor). The computing device or processor is, for example, a general-purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), and the like. Or other programmable logic devices. Various embodiments may also be implemented or embodied by a combination of these devices. In particular, each functional block used in the description of each of the above-described embodiments can be implemented by an LSI that is an integrated circuit. These functional blocks may be composed of individual chips, or may be composed of one chip so as to include a part or all of the functional blocks. These chips can contain inputs and outputs of data coupled to them. LSIs are called ICs, system LSIs, super LSIs, or ultra LSIs depending on the degree of integration. However, the technique for implementing an integrated circuit is not limited to LSI, and can be achieved by using a dedicated circuit or a general-purpose processor. Further, an FPGA that can be programmed after the LSI is manufactured, or a reconfigurable processor that can reset the connection or setting of the circuit cell inside the LSI may be used.

In addition, various embodiments may also be implemented by software modules. These software modules are executed by the processor or directly in the hardware. It is also possible to combine software modules and hardware implementations. The software module may be stored in any kind of computer readable storage medium such as RAM, EPROM, EEPROM, flash memory, registers, hard disk, CD-ROM, DVD and the like. Furthermore, it should be noted that the individual features of a plurality of different embodiments can be the subject of another embodiment individually or in any combination.

It will be appreciated by those skilled in the art that the present disclosure set forth in a specific embodiment may be modified and / or modified in various ways without departing from the broadly defined concepts or scope of the invention. Will be done. Accordingly, the embodiments presented herein are considered exemplary in all respects and are not intended to limit the invention.

Claims (8)

An integrated circuit that controls the processing of a transmitter to determine which radio resource should be used for data transmission to one or more receivers via a sidelink interface.
The transmitter performs a resource sensing procedure and obtains information about radio resources that can be used to transmit data at a later time.
Autonomous radio resources based on the information acquired by the resource sensing procedure in the sensing window after the data is available for transmission and before the data is available for transmission. Perform the allocation, select the radio resource in the transmit window that should be used to transmit the data,
The autonomous radio resource allocation selects a radio resource in the primary subframe of the transmit window over a radio resource in the secondary subframe of the transmit window.
The secondary subframe in the transmit window corresponds to the subframe in the sensing window for which the transmitter did not perform the resource sensing procedure during the period of the sensing window, and the primary subframe in the transmit window. Corresponds to a subframe in the sensing window in which the transmitter performed the resource sensing procedure during the period of the sensing window, the secondary subframe being the minimum reservation of the radio resource that can be made by other transmitters. Determined based on the cycle of
The data is associated with a priority (PPPP) for each ProSe packet that indicates the priority of the data.
Integrated circuit. The resource sensing procedure is
• Monitor scheduling information transmitted by other transmitters to indicate radio resources reserved by said other transmitters for later time to determine radio resources reserved by other transmitters. To do and
It comprises measuring the received signal energy in the radio resource to identify the radio resource used by another transmitter for transmission.
The integrated circuit according to claim 1. The autonomous radio resource allocation further determines one or more primary transmit radio resource candidates within the primary subframe and one or more secondary transmit radio resource candidates within the secondary subframe. Be prepared to do
If there are a plurality of primary transmit radio resource candidates, the candidate ranking of the primary transmit radio resource candidate is executed, and if there are a plurality of secondary transmit radio resource candidates, the candidate ranking of the secondary transmit radio resource candidate is executed. The candidate ranking of the one or more primary transmit radio resource candidates is separate from the ranking of the one or more secondary transmit radio resource candidates.
The candidate ranking includes the time distance of the radio resource candidate from the time when the data became available for transmission, and the received signal acquired by the resource sensing procedure for the radio resource to be ranked. Considering the predicted value of energy,
The predicted value of the received signal energy of the radio resource to be ranked is based on the measured value of the received signal energy of the corresponding radio resource in all subframes of the sensing window, or is ranked by the radio resource. Based on the measured value of the received signal energy of the corresponding radio resource in the subframe of the sensing window associated with the subframe to be done, the relevant subframe has a number of possible transmission cycles by other transmitters. A subframe of the sensing window having a time distance from the radio resource to be ranked.
The candidate ranking first considers the time distance and then the received signal energy, or the candidate ranking first considers the received signal energy and then the time distance, or The candidate ranking is based on a function of the time distance and the received signal energy.
The integrated circuit according to any one of claims 1 and 2. When the transmitting device executes data transmission or scheduled allocation transmission for data transmission in a subframe, the transmitting device does not execute the resource sensing procedure in the subframe.
The integrated circuit according to any one of claims 1 to 3. Discard the data if the radio resource to be used for transmission of the data cannot be selected and the priority of the data available for transmission is below the preemption priority threshold. And if the data is not discarded, perform a resource preemption procedure and use it to transmit the data from among the radio resources reserved by one or more of the other transmitters. Select the radio resource to be done and
When performing the resource preemption procedure, the radio resource to be used for transmission of the data is the priority of the reserved radio resource and / or the priority of the data to be transmitted. , And / or selection based on the received signal energy measured by the resource sensing procedure in the radio resource of the corresponding subframe in the sensing window, and the selection of the radio resource in the resource preemption procedure is first described above. The priority is then considered the received signal energy of the reserved radio resource, or first the received signal energy and then the priority of the reserved radio resource, or Either based on the function of the priority of the reserved radio resource and the received signal energy.
The integrated circuit according to any one of claims 1 to 4. The process determines the channel busy rate of the side link interface, which indicates the congestion level of the side link interface, and determines whether or not the data available for transmission should be discarded. If, based on the determined channel busy rate of the side link interface, the data discard procedure is performed prior to performing the autonomous radio resource allocation and it is determined not to discard the data, the autonomous Perform radio resource allocation and
When it is determined during the data discard procedure that the priority of the data made available for transmission is lower than the channel priority threshold, the data is discarded and the channel priority threshold is used. Depends on the determined channel busy rate of the side link interface.
The transmitting device is set by a radio base station that controls the transmitting device to perform or not perform the data discarding procedure, and the setting of the data discarding procedure selects radio resources for transmitting data. For each of the multiple resource pools available by the transmitter, it is separate and
The channel priority threshold further depends on the type of data available for transmission, and the safety data-related channel priority threshold is higher than the unsafe data-related channel priority threshold. Low,
The integrated circuit according to any one of claims 1 to 5. The autonomous radio resource allocation comprises excluding radio resources reserved by the other transmitter from the plurality of radio resources and / or.
Radio resource candidates within a subframe include one or more contiguous resource blocks in the frequency domain.
The integrated circuit according to any one of claims 1 to 6. The sensing window considered for the autonomous radio resource allocation starts at a predetermined time point before the data is available for transmission and the data is available for transmission. Equipped with frequency time radio resources, which ends when
The transmit window is a frequency-time radio that begins at the start subframe immediately following the subframe in which the data is available for transmission and ends at a subframe that is a predetermined time distance away from the start subframe. With resources, the time distance depends on the data delay requirements available for transmission to be met by the transmitter.
The integrated circuit according to any one of claims 1 to 7.

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