JP7183351B2 - Multiple ProSe Group Communication During Sidelink Control Period - Google Patents

Description

The present disclosure relates to a method of allocating radio resources to a transmitting user equipment for performing direct communication transmissions over direct sidelink connections to one or more receiving user equipment. Further, the present disclosure provides user equipment and base stations involved in the methods described herein.

<Long Term Evolution (LTE)>
The third generation mobile communication system (3G), based on WCDMA(R) radio access technology, is being deployed on a wide scale around the world. The first step in enhancing or evolving this technology is the introduction of High Speed Downlink Packet Access (HSDPA) and Enhanced Uplink (also known as High Speed Uplink Packet Access (HSUPA)), which provides , provides extremely competitive radio access technology.

In order to meet the increasing demand from users and to ensure competitiveness with new radio access technologies, 3GPP has introduced a new mobile communication system called Long Term Evolution (LTE). LTE is designed to provide carriers with the demand for high-speed transmission of data and media as well as high-capacity voice support over the next decade. The ability to provide high bitrates is a key strategy in LTE.

Work Item (WI) specifications for LTE (Long Term Evolution) are Evolved UMTS Terrestrial Radio Access (UTRA) and E-UTRAN (Evolved UMTS Terrestrial Radio Access Network (UTRAN)). : Evolved UMTS Terrestrial Radio Access Network) and will eventually be published as Release 8 (LTE Release 8). The LTE system is a packet-based efficient radio access and radio access network that offers all IP-based functionality with low latency and low cost. In LTE, scalable multiple transmission bandwidths (e.g., 1.4 MHz, 3.0 MHz, 5.0 MHz, 10.0 MHz, 15.0 MHz, and 20.0 MHz) are specified. Radio access based on OFDM (Orthogonal Frequency Division Multiplexing) is employed for the downlink. Because such radio access is inherently immune to multipath interference (MPI) due to its low symbol rate, it uses a cyclic prefix (CP), and it supports various transmission bandwidth configurations. Because it is possible. The uplink employs SC-FDMA (Single-Carrier Frequency Division Multiple Access) based radio access. This is because, given the limited transmit power of user equipment (UE), providing a wider coverage area is prioritized over improving peak data rates. LTE Release 8/9 adopts a number of key packet radio access technologies (eg, MIMO (Multiple Input Multiple Output) channel transmission technology) to achieve a highly efficient control signaling structure.

<LTE architecture>
Figure 1 shows the overall architecture of LTE. E-UTRAN consists of eNodeBs, which terminate E-UTRA user plane (PDCP/RLC/MAC/PHY) and control plane (RRC) protocols towards user equipment (UE). The eNodeB (eNB) consists of 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 are user plane header compression and ciphering). ), including the functionality of The eNB also provides radio resource control (RRC) functionality for the control plane. The eNB provides radio resource management, admission control, scheduling, negotiated uplink Quality of Service (QoS) enforcement, broadcast of cell information, encryption/decryption of user plane and control plane data, downlink/uplink It performs many functions such as compression/decompression of user plane packet headers. Multiple eNodeBs are connected to each other by an X2 interface.

In addition, the plurality of eNodeBs are connected to an EPC (Evolved Packet Core) through the S1 interface, more specifically, an MME (Mobility Management Entity) through the S1-MME, and a serving gateway ( SGW: Serving Gateway). The S1 interface supports many-to-many relationships between MME/Serving Gateways and eNodeBs. The SGW routes and forwards user data packets, while acting as a mobility anchor for the user plane during handovers between eNodeBs, and also as an anchor for mobility between LTE and another 3GPP technology (S4 terminating interfaces and relaying traffic between the 2G/3G system and the PDN GW). The SGW terminates the downlink data path for idle user equipment and triggers paging when downlink data arrives for that user equipment. The SGW manages and stores user equipment context (eg IP bearer service parameters, or network internal routing information). Furthermore, the SGW performs duplication of user traffic in case of lawful interception.

The MME is the main control node of the LTE access network. The MME is responsible for idle mode user equipment tracking and paging procedures (including retransmissions). The MME is involved in the bearer activation/deactivation process and also selects the SGW for the user equipment during initial attach and during intra-LTE handover with core network (CN) node relocation. also play a role in The MME is responsible for authenticating the user (by interacting with the HSS). Non-Access Stratum (NAS) signaling is terminated at the MME, which is also responsible for generating and assigning temporary identities to user equipment. The MME checks the authorization of the user equipment to enter the service provider's Public Land Mobile Network (PLMN) and enforces roaming restrictions for the user equipment. The MME is the termination point in the network for ciphering/integrity protection of NAS signaling and is responsible for security key management. Lawful interception of signaling is also supported by the MME. In addition, the MME provides control plane functions for mobility between LTE and 2G/3G access networks and terminates the S3 interface from the SGSN. Additionally, the MME terminates the S6a interface towards the home HSS for roaming user equipment.

<Component carrier structure in LTE>
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 Figure 2, where the first downlink slot covers the control channel region (PDCCH region) within the first OFDM symbol. Prepare. Each subframe consists of a given number of OFDM symbols in the time domain (12 or 14 OFDM symbols in 3GPP LTE (Release 8)), each OFDM symbol spanning the entire bandwidth of a component carrier. Each OFDM symbol is thus composed of a number of modulation symbols transmitted on respective subcarriers. In LTE _, the transmitted signal in each slot is described by a resource grid of N ^DL _RB ×N ^RB _sc subcarriers and N ^DL symb OFDM symbols. N ^DL _RB is the number of resource blocks in the bandwidth. The number N ^DL _RB depends on the downlink transmission bandwidth configured in the cell and satisfies N ^min,DL _RB ≦N ^DL _RB ≦N ^max,DL _RB , where N ^min,DL _RB =6 and N ^max,DL _RB =110 are the minimum and maximum downlink bandwidths respectively supported by the current version of the specification. N ^RB _sc is the number of subcarriers in one resource block. For the normal cyclic prefix subframe structure, N ^RB _sc =12 and N ^DL _symb =7.

Assuming a multi-carrier communication system, eg using OFDM, eg as used in 3GPP Long Term Evolution (LTE), the smallest unit of resource that can be allocated by the scheduler is one "resource block". A physical resource block (PRB) consists of consecutive OFDM symbols in the time domain (eg, 7 OFDM symbols) and consecutive subcarriers in the frequency domain (eg, 12 subcarriers of a component carrier), as illustrated in FIG. defined as Thus, in 3GPP LTE (Release 8), a physical resource block consists of resource elements and corresponds to one slot in the time domain and 180 kHz in the frequency domain (further details on the downlink resource grid can be found e.g. See Section .2 (available on the 3GPP website and incorporated herein by reference)).

One subframe consists of two slots, so there are 14 OFDM symbols in a subframe when the so-called "normal" CP (cyclic prefix) is used and the so-called "extended" CP is There are 12 OFDM symbols in a subframe when used. For the purpose of terminology, time-frequency resources equivalent to the same contiguous subcarriers spanning an entire subframe are hereinafter referred to as "resource block pairs" or equivalently "RB pairs" or "PRB pairs".

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

Similar assumptions regarding the structure of the component carrier apply to subsequent releases.

<Carrier aggregation in LTE-A for wider bandwidth support>
At the World Radiocommunication Conference 2007 (WRC-07), the frequency spectrum for IMT-Advanced was decided. Although the overall frequency spectrum for IMT-Advanced has been determined, the actual available frequency bandwidth varies by region and country. However, following the determination of the outline of the available frequency spectrum, the standardization of the radio interface started in 3GPP (3rd Generation Partnership Project). At the 3GPP TSG RAN #39 meeting, the description of the study item on "Further Advancements for E-UTRA (LTE-Advanced)" was approved. This study item covers technical elements that should be considered in evolving E-UTRA (eg, to meet the requirements of IMT-Advanced).

The bandwidth that an LTE Advanced system can support is 100 MHz, while an LTE system can only support 20 MHz. Today, the lack of radio spectrum has become a bottleneck in the development of wireless networks, and as a result it is difficult to find wide enough spectrum bands for LTE Advanced systems. Therefore, there is an urgent need to find a way to acquire wider wireless spectrum bands, where a possible answer is carrier aggregation function.

In carrier aggregation, two or more component carriers are aggregated in order to support wider transmission bandwidths up to 100 MHz. In LTE-Advanced system, several cells in LTE system are aggregated into one wider channel, which is wide enough for 100MHz even if these cells in LTE are in different frequency bands. .

All component carriers can be configured to be LTE Release 8/9 compatible, at least when the component carrier bandwidth does not exceed the supported bandwidth of an LTE Release 8/9 cell. Not all component carriers aggregated by a user equipment are necessarily LTE Release 8/9 compatible. Existing mechanisms (eg, barring) can be used to prevent Rel-8/9 user equipment from camping on component carriers.

A user equipment can simultaneously receive or transmit on one or multiple component carriers (corresponding to multiple serving cells) depending on its capabilities. An LTE-A Release 10 user equipment with receive and/or transmit capabilities for carrier aggregation can simultaneously receive and/or transmit on multiple serving cells, whereas LTE A Rel-8/9 user equipment can receive and transmit on only one serving cell if the component carrier structure complies with the Rel-8/9 specifications.

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

Configuring 3GPP LTE-A (Release 10) compatible user equipment to aggregate different numbers of component carriers, possibly with different bandwidths in the uplink and downlink, transmitted from the same eNodeB (base station) It is possible to The number of downlink component carriers that can be configured 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 capability of the user equipment. Currently, it is not possible to set the 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 uplink and downlink. Component carriers transmitted from the same eNodeB need not provide the same coverage.

The spacing of the center frequencies of the continuously aggregated component carriers is a multiple of 300 kHz. This is to maintain compatibility with the 100 kHz frequency raster of 3GPP LTE (Release 8/9) while maintaining orthogonality of 15 kHz spaced subcarriers. In some aggregation scenarios, n×300 kHz spacing can be facilitated by inserting a small number of unused subcarriers between consecutive component carriers.

The impact of aggregating multiple carriers only extends to the MAC layer. The MAC layer requires one HARQ entity per aggregated component carrier in both uplink and downlink. There is a maximum of 1 transport block per component carrier (without using SU-MIMO in the uplink). A transport block and its HARQ retransmissions (when they occur) should be mapped to the same component carrier.

When carrier aggregation is configured, the mobile terminal has only one RRC connection with the network. During RRC connection establishment/re-establishment, one cell receives security inputs (one ECGI, one PCI, and one ARFCN) and non-access stratum (NAS) mobility information ( e.g. TAI). After establishment/re-establishment of the RRC connection, the component carrier corresponding to that cell is called downlink primary cell (PCell). In connected state, there is always one downlink PCell (DL PCell) and one uplink PCell (UL PCell) per user equipment. In a configured set of component carriers, the other cells are called secondary cells (SCells), and the carriers of the SCells are downlink secondary component carriers (DL SCC) and uplink secondary component carriers (UL SCC). Up to five serving cells (including PCell) can be configured for one UE.

The characteristics of the downlink PCell and the uplink PCell are as follows.
- Per SCell, the use by the user equipment of uplink resources in addition to downlink resources can be configured (so the number of DL SCCs configured is always greater or equal to the number of UL SCCs and the number of uplink SCell cannot be configured to use only resources).
• Downlink PCells cannot be deactivated unlike SCells.
• Rayleigh fading (RLF) on the downlink PCell triggers re-establishment, but RLF on the downlink SCell does not trigger re-establishment.
• Non-access stratum information is obtained from the downlink PCell.
• The PCell can only be changed by handover procedures (ie security key change and RACH procedures).
- PCell is used for transmission of PUCCH.
- The uplink PCell is used to transmit Layer 1 uplink control information.
• From the UE's point of view, each uplink resource belongs to only one serving cell.

Configuration and reconfiguration, addition and deletion of component carriers can be performed by RRC. Activation and deactivation are done via MAC control elements. During intra-LTE handover, RRC may also add, remove, or reconfigure SCells for use in the target cell. When adding a new SCell, dedicated RRC signaling is used to send the SCell's system information (required for transmission/reception) (similar to during handover in LTE Release 8/9). When a SCell is added to a UE, each SCell is configured with a serving cell index. A PCell always has a serving cell index of 0.

When the user equipment is configured to use carrier aggregation, at least one pair of uplink and downlink component carriers is always active. A downlink component carrier of this pair is sometimes referred to as a "downlink anchor carrier." The same is true for the uplink.

When carrier aggregation is configured, user equipment can be scheduled on multiple component carriers at the same time, but at most one random access procedure can be in progress at the same time. Cross-carrier scheduling allows the PDCCH of a component carrier to schedule resources of another component carrier. For this purpose, a component carrier identification field (referred to as "CIF") is introduced in each DCI (Downlink Control Information) format.

When cross-carrier scheduling is not in effect, the uplink component carrier to downlink component carrier link (established by RRC signaling) may identify the uplink component carrier to which the grant applies. The linking of downlink component carriers to uplink component carriers does not necessarily have to be one-to-one. In other words, more than one downlink component carrier can be linked to the same uplink component carrier. On the other hand, one downlink component carrier can only be linked to one uplink component carrier.

<Uplink access method in LTE>
Uplink transmission requires power efficient transmission by the user terminals in order to maximize coverage. A combination of single-carrier transmission and FDMA with dynamic bandwidth allocation has been chosen as the uplink transmission scheme for E-UTRA. Single-carrier transmission was chosen primarily because of its lower peak-to-average power ratio (PAPR) and correspondingly improved power amplifier efficiency and improved coverage compared to multi-carrier signals (OFDMA). (high data rate for given terminal peak power). In each time interval, the NodeB assigns users unique time/frequency resources for transmitting user data, thereby ensuring orthogonality within the cell. Orthogonal multiple access in the uplink increases spectral efficiency by eliminating intra-cell interference. Interference due to multipath propagation is addressed at the base station (NodeB) by inserting a cyclic prefix into the transmitted signal.

The basic physical resource used to transmit data consists of a frequency resource of size BW _grant over one time interval (e.g. a subframe of 0.5 ms) (the coded information bits are ). It should be noted that a subframe (also called transmission time interval (TTI)) is the minimum time interval for transmitting user data. However, by concatenating subframes, it is also possible to allocate frequency resources BW _grant to users for longer than one TTI.

<Uplink scheduling method in LTE>
Uplink schemes in LTE allow both scheduled access (ie controlled by the eNB) and contention-based access.

For scheduled access, a UE is assigned a specific frequency resource (ie, time/frequency resource) for a specific amount of time to transmit uplink data by the eNB. Some time/frequency resources can be allocated for contention-based access, and a UE can transmit in this time/frequency resource without being scheduled by the eNB first. One scenario in which the user equipment has contention-based access is for example random access, i.e. when the UE makes its first access to a cell or when it makes its first access to request uplink resources. is.

For scheduled access, the NodeB scheduler assigns users unique time-frequency resources for uplink data transmission. More specifically, the scheduler determines:
- UE(s) to allow transmission
・Physical channel resources ・Transport format (modulation and coding scheme (MCS)) that the mobile terminal should use for transmission

Allocation information is signaled to the UEs via scheduling grants sent on the L1/L2 control channel. In the following, this channel will be referred to as an uplink grant channel for the sake of brevity. Therefore, the scheduling grant message contains as information the part of the frequency band that is allowed to be used by the UE, the validity period of the grant and the transport format that the UE must use for upcoming uplink transmissions. . The shortest validity period is one subframe. Additional information may also be included in the grant message depending on the scheme chosen. For grants granting the right to transmit on the uplink shared channel (UL-SCH), only 'per UE' grants are used (ie there is no 'per radio bearer in each UE' grant). Therefore the UE needs to distribute the allocated resources among the radio bearers according to some rules. The transport format is not selected at the user equipment side, unlike in HSUPA. The eNB decides the transport format based on some information (eg reported scheduling information and QoS information) and the user equipment has to comply with the selected transport format. In HSUPA, the NodeB allocates maximum uplink resources and the UE selects the actual transport format for data transmission accordingly.

Since radio resource scheduling is the most important function in shared channel access networks in determining service quality, uplink scheduling schemes in LTE have been met in order to enable efficient quality of service (QoS) management. There are some requirements that should be met.
・A lack of resources for low-priority services should be avoided.
- The quality of service (QoS) should be clearly demarcated for each radio bearer/service.
Fine-grained buffer reporting (e.g. per radio bearer or per radio bearer group reporting) in uplink reporting so that the eNB scheduler can identify which radio bearer/service data is being transmitted. should be able to
• It should be possible to clearly distinguish the Quality of Service (QoS) between services of different users.
• It should be possible to provide a minimum bit rate per radio bearer.

As can be seen from the set of conditions listed above, one important aspect of the LTE scheduling scheme is that operators can distribute their total cell capacity among individual radio bearers of different QoS classes. is to provide a mechanism that can control The radio bearer QoS class is identified by the corresponding SAE bearer QoS profile signaled from the serving gateway to the eNB as described above. An operator can allocate a certain amount of its total cell capacity to the total traffic associated with radio bearers of a certain QoS class. The main purpose of adopting this class-based method is to allow the handling of packets to be differentiated according to the QoS class to which they belong.

<Layer 1/Layer 2 Control Signaling>
L1/L2 control signaling is used to inform scheduled users of their allocation status, transport format, and other transmission-related information (e.g., HARQ information, transmit power control (TPC) commands). Sent on the downlink along with the data. Layer 1/Layer 2 control signaling is multiplexed together with downlink data in subframes (assuming user allocation can change from subframe to subframe). Note that user allocation can also be performed on a TTI (Transmission Time Interval) basis, in which case the TTI length can be a multiple of subframes. The TTI length can be constant for all users within the coverage area, different lengths for different users, or even dynamic for each user. Layer 1/Layer 2 control signaling typically only needs to be transmitted once per TTI. In the following, without loss of generality, we assume that the TTI is equal to one subframe.

Layer 1/Layer 2 control signaling is transmitted on the physical downlink control channel (PDCCH). The PDCCH carries messages as downlink control information (DCI), which in most cases contain resource allocations and other control information intended for a group of mobile terminals or UEs. In general, several PDCCHs can be transmitted within one subframe.

Note that in 3GPP LTE, allocations for uplink data transmission (also called uplink scheduling grants or uplink resource allocations) are also transmitted on the PDCCH. Furthermore, 3GPP Release 11 introduced EPDCCH, which basically performs the same function as PDCCH (ie carries L1/L2 control signaling), but the details of the transmission method are different from PDCCH. Further details can be found, inter alia, in the current versions of Non-Patent Documents 1 and 2 (incorporated herein by reference). Therefore, most of the items outlined in the background and embodiments apply to PDCCH and EPDCCH or other means of conveying L1/L2 control signaling unless otherwise stated.

Information sent in L1/L2 control signaling for the purpose of allocating uplink radio resources or downlink radio resources (especially LTE(-A) Release 10) can be generally classified into the following items: can.
- User identification information: Indicates the user to be assigned. This information is commonly included in the checksum by masking the CRC with user identification information.
- resource allocation information: indicates the resource (eg resource block (RB)) allocated to the user. Alternatively, this information is called Resource Block Allocation (RBA). Note that the number of resource blocks (RBs) allocated to a user can be dynamic.
- Carrier indicator: used when a control channel transmitted on a first carrier allocates resources associated with a second carrier (i.e. resources of the second carrier or resources associated with the second carrier) ( cross-carrier scheduling).
- Modulation/coding method: Determine the modulation method and coding rate to be adopted.
- HARQ information: such as New Data Indicator (NDI) and Redundancy Version (RV), which are particularly useful when retransmitting data packets or parts thereof.
– power control command: adjusts the transmission power when transmitting data or control information on the allocated uplink;
- Reference signal information: such as applied cyclic shifts and orthogonal cover code indices used to transmit or receive the reference signal to be assigned.
- Uplink Allocation Index or Downlink Allocation Index: Used to identify the order of allocation, particularly useful in TDD systems.
- Hopping information: for example, whether and how to apply resource hopping for the purpose of increasing frequency diversity.
- CSI request: used to trigger the transmission of channel state information on the allocated resources.
- Multi-cluster information: used to indicate and control whether the transmission is in a single cluster (a contiguous set of resource blocks) or multi-cluster (at least two non-contiguous sets of contiguous resource blocks). is a flag. Multi-cluster allocation was introduced by 3GPP LTE-(A) Release 10.

Note that the above list is not exhaustive, and depending on the DCI format used, not all listed information items need to be included in each PDCCH transmission.

Downlink control information takes the form of several formats, which differ in overall size and the information contained in the fields mentioned above. The different DCI formats currently defined in LTE are: , incorporated herein by reference). Further details regarding the DCI format and the specific information transmitted in the DCI can be found in the technical standards listed above, or Section 9.3 of Non-Patent Document 4 (incorporated herein by reference). See
- Format 0: DCI format 0 is used to transmit resource grants for PUSCH using single-antenna port transmission in uplink transmission modes 1 or 2;
- Format 1: DCI format 1 is used to transmit resource allocations for single codeword PDSCH transmissions (downlink transmission modes 1, 2, 7).
- Format 1A: DCI format 1A is intended for compact signaling of resource allocation for single codeword PDSCH transmission and for allocating dedicated preamble signatures to mobile terminals for contention-free random access. and (all transmission modes).
- Format 1B: DCI format 1B is used to compactly signal resource allocation for PDSCH transmission (downlink transmission mode 6) using closed-loop precoding with rank-1 transmission. The transmitted information is the same as in format 1A, but additionally an indicator of the precoding vector applied to PDSCH transmission is transmitted.
- Format 1C: DCI format 1C is used to transmit PDSCH assignments very compactly. When format 1C is used, PDSCH transmission is constrained to use QPSK modulation. This format is used, for example, to signal paging messages and broadcast system information messages.
- Format 1D: DCI format 1D is used to compactly signal resource allocation for PDSCH transmission with multi-user MIMO. The information transmitted is the same as for format 1B, but instead of one of the bits in the precoding vector indicator, there is one bit to indicate whether a power offset is applied to the data symbols. exist. This configuration is necessary to indicate whether or not transmit power is shared between the two user equipments. In future versions of LTE, this configuration may be extended for power sharing among a larger number of user equipments.
- Format 2: DCI format 2 is used to transmit resource allocation for PDSCH in case of closed-loop MIMO operation (transmission mode 4).
- Format 2A: DCI format 2A is used to transmit resource allocation for PDSCH in case of open-loop MIMO operation. The transmitted information is the same as for format 2, except that if the eNodeB has 2 transmit antenna ports, there is no precoding information, and for 4 antenna ports, to indicate the transmission rank. 2 bits are used for (transmission mode 3).
- Format 2B: Introduced in Release 9 and used to transmit resource allocation for PDSCH in case of dual-layer beamforming (transmission mode 8).
- Format 2C: Introduced in Release 10 and used to transmit resource allocation for PDSCH in case of closed-loop single-user MIMO operation or multi-user MIMO operation (up to 8 layers) (transmission mode 9).
- Format 2D: Introduced in Release 11, used for transmission of up to 8 layers, mainly used in CoMP (Coordinated Multipoint) (transmission mode 10).
- Formats 3 and 3A: DCI formats 3 and 3A are used to transmit power control commands for PUCCH and PUSCH, with 2-bit or 1-bit power adjustment, respectively. These DCI formats contain individual power control commands for groups of user equipment.
- Format 4: DCI format 4 is used for scheduling PUSCH using closed-loop spatial multiplexing transmission in uplink transmission mode 2;
- Format 5: DCI format 5 is used for scheduling PSCCH (Physical Sidelink Control Channel) and SCI used for scheduling PSSCH (Physical Sidelink Shared Control Channel) Contains some fields of format 0. The number of information bits in DCI format 5 mapped to a given search space is less than the payload size of format 0 for scheduling the same serving cell, and the payload size of format 5 does not include the padding bits added to format 0. Add zeros to format 5 until it equals the payload size of format 0, including

Section 5.4.3 of the 3GPP technical standard Non-Patent Document 3 (current version 12.4.0), which is incorporated herein by reference, defines sidelink control information. (more on sidelinks later).

SCI (Sidelink Control Information) can carry sidelink scheduling information for one destination ID. SCI format 0 is defined for use in PSSCH scheduling. The following information is transmitted by SCI format 0.
- Frequency hopping flag: 1 bit - Resource block allocation and hopping resource allocation - Time resource pattern: 7 bits - Modulation/coding method: 5 bits - Timing advance indication: 11 bits - Group destination ID: 8 bits

<Logical channel prioritization (LCP) procedure>
For the uplink, the process by which the UE creates MAC PDUs for transmission using the assigned radio resources is fully standardized and is optimized and consistent across different implementations of the UE. , the UE is designed to meet the QoS of each configured radio bearer. The UE must determine the amount of data for each logical channel to include in the new MAC PDU based on the uplink transmission resource grant message signaled on the PDCCH and, if necessary, space for MAC control elements. must be assigned.

When constructing a MAC PDU with data from multiple logical channels, the simplest and most intuitive method is based on absolute priority, in which space in the MAC PDU is divided between logical channel priorities. Assign logical channels in descending order. That is, process the data from the highest priority logical channel first in the MAC PDU, followed by the data from the next highest priority logical channel, and so on until the MAC PDU space is all occupied. . The absolute priority based method is quite simple in terms of UE implementation, but in some cases can lead to resource starvation of data from low priority logical channels. Insufficient resources means that data from lower priority logical channels cannot be transmitted because data from higher priority logical channels occupy all the space in the MAC PDU.

In LTE, a prioritized bit rate (PBR) is defined for each logical channel for the purpose of transmitting data in order of importance while also avoiding resource shortages for low priority data. PBR is the guaranteed minimum data rate for a logical channel. Even if the logical channel has low priority, at least a small amount of MAC PDU space is allocated to guarantee PBR. The resource scarcity problem can therefore be avoided by using PBR.

The step of constructing a MAC PDU using PBR consists of two substeps. In the first substep, each logical channel is processed in descending order of logical channel priority, but the amount of data from each logical channel to include in the MAC PDU is initially reduced to the PBR value set for that logical channel. Limit to a corresponding amount. After processing all logical channels to their respective PBR values, if there is space left in the MAC PDU, perform the second substep. In the second substep, each logical channel is again processed in descending order of priority. The main difference in the second sub-step compared to the first sub-step is that MAC PDU space is allocated to each low priority logical channel only when there is no more data to send on all high priority logical channels. can be assigned.

A MAC PDU may include a MAC CE as well as a MAC SDU from each configured logical channel. Except for padding BSR, MAC CE has higher priority than MAC SDUs from logical channels, because MAC CE controls the operation of the MAC layer. Therefore, when constructing a MAC PDU, the MAC CE (if any) is included first, and the remaining space is used for MAC SDUs from logical channels. Then, if there is more space left and it is large enough to contain the BSR, the Padding BSR is triggered and included in the MAC PDU. A logical channel prioritization (LCP) procedure is applied each time a new transmission is performed.

Logical channel prioritization is standardized, for example, in Non-Patent Document 5 (current version 12.5.0), section 5.4.3.1 (incorporated herein by reference).

RRC controls uplink data scheduling by signaling the following for each logical channel:
priority (higher priority values indicate lower priority levels);
・ prioritizedBitRate (sets the priority bit rate (PBR))
- bucketSizeDuration (sets the bucket size duration (BSD))

The UE maintains a variable B _j for each logical channel j. _Bj is initialized to 0 when the associated logical channel is established, and is incremented by the product PBR*TTI duration every TTI (PBR is the preferred bit rate for logical channel j). However, the value of _Bj cannot exceed the bucket size, and when the value of _Bj is greater than the bucket size of logical channel j, the value of _Bj is set to the bucket size. The bucket size of a logical channel is equal to PBR (priority bit rate) times BSD (bucket size period), where PBR and BSD are set by higher layers.

<LTE Device-to-Device (D2D) Proximity Service (ProSe)>
Proximity-based applications and services are a new trend in social technology. Areas identified include commercial services of interest to operators and users and services related to public safety. By introducing Proximity Services (ProSe) capabilities to LTE, the 3GPP industry will be able to serve this potential growth market while coordinating with the emergence of several public safety communities using LTE. can meet your needs.

Device-to-device (D2D) communication is a technology component in LTE Release-12. Device-to-device (D2D) communication technologies can increase spectral efficiency with D2D as an underlay to 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 equipments transmit data signals to each other over direct links using cellular resources without going through radio base stations. Throughout the invention, the terms "D2D", "ProSe" and "sidelink" are synonymous.

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

ProSe (Proximity Service) Direct Discovery allows a ProSe-enabled user equipment to identify another (one or more) ProSe-enabled user equipment in its vicinity using E-UTRA direct radio signals over the PC5 interface. Defined as the procedure used to discover using. Figure 3 schematically shows the PC5 interface for direct discovery between devices. FIG. 4 schematically shows a radio protocol stack (AS) for ProSe direct discovery.

In D2D communication, UEs transmit data signals to each other over direct links using cellular resources without going through a base station (BS). D2D users communicate directly but remain under the control of the base station (at least when within the coverage of the eNB). Therefore, D2D can improve system performance by reusing cellular resources.

D2D is assumed to operate in the uplink LTE spectrum (for FDD) or in the uplink subframes of the cell providing coverage (for TDD, except when out of coverage). Furthermore, D2D transmission/reception does not use full duplex on a given carrier. From an individual user equipment perspective, full duplex with D2D signal reception and LTE uplink transmission on a given carrier is not used (ie D2D signal reception and LTE uplink transmission cannot occur simultaneously).

In D2D communication, when one particular UE1 is in the role of transmitting (transmitting user equipment or transmitting terminal), UE1 sends data and another UE2 (receiving user equipment) receives it. UE1 and UE2 can exchange roles of transmission and reception. A transmission from UE1 may be received by one or more UEs similar to UE2.

Concerning the user plane protocol, the agreement related to D2D communication is shown below (Section 9.2.2 of Non-Patent Document 6 (current version 12.0.1) (incorporated herein by reference) )).

・PDCP:
- 1: M D2D broadcast communication data (ie IP packets) should be treated as normal user plane data.
- 1: For MD2D broadcast communication data, header compression/decompression in PDCP can be applied.
• For public safety related D2D broadcast operations, use U-mode for header compression in PDCP.

- RLCs:
- 1: Use RLC UM for MD2D broadcast communication.
- Segmentation and reconstruction are supported at Layer 2 by RLC UM.
- The receiving user equipment shall maintain at least one RLC UM entity per sending peer user equipment.
- There is no need to configure the receiver's RLC UM entity before receiving the first RLC UM data unit.
- Currently, there is no recognized need for RLC AM or RLC TM in D2D communications that transmit user plane data.

・MAC:
- 1: HARQ feedback is not assumed in MD2D broadcast communication.
– The receiving user equipment needs to know the Source ID for the purpose of identifying the receiver's RLC UM entity.
- The MAC header contains a layer 2 (L2) destination ID that enables packet filtering at the MAC layer.
- The layer 2 (L2) destination ID can be a broadcast address, a groupcast address, or a unicast address.
Layer 2 (L2) Groupcast/Unicast: By the Layer 2 (L2) destination ID conveyed in the MAC header, the received RLC UM PDU is sent even before passing it to the receiver's RLC entity. can be discarded.
• Layer 2 (L2) Broadcast: The receiving user equipment processes all received RLC PDUs from all transmitters, reassembles and passes IP packets to upper layers.
- The MAC subheader contains a Logical Channel ID (LCID) (to distinguish between multiple logical channels).
- In D2D at least multiplexing/demultiplexing, priority handling and padding are useful.

<Identification information related to ProSe direct communication>
Section 8.3 of Non-Patent Document 7 (current version 12.5.0) defines the following identities for use in ProSe direct communication:

• SL-RNTI: A unique identifier used for scheduling ProSe direct communications • Source Layer 2 ID: Identifies the sender of data in sidelink ProSe direct communications. The Source Layer 2 ID is 24 bits long and is used together with the ProSe Layer 2 Destination ID and LCID (Logical Channel ID) to identify the RLC UM and PDCP entities at the receiver.
• Destination Layer 2 ID: Identifies the target of the data in sidelink ProSe direct communication. The Destination Layer 2 ID is 24 bits long and is split into two bitstrings at the MAC layer.
• One bit string is the least significant part (8 bits) of the destination Layer 2 ID and is forwarded to the physical layer as the Sidelink Control Layer 1 ID. It identifies the intended data target for sidelink control and is used for packet filtering at the physical layer.
• The second bit string is the most significant part (16 bits) of the destination Layer 2 ID, carried in the MAC header. This is used for packet filtering at the MAC layer.

No access stratum signaling is required to form the group and set the source layer 2 ID, destination layer 2 ID and sidelink control L1 ID in the UE. These identities are provided by higher layers or are derived from identities provided by higher layers. For groupcasts and broadcasts, the ProSe UE ID provided by the higher layers is used directly as the source Layer 2 ID and the ProSe Layer 2 Group ID provided by the higher layers is used directly as the destination Layer 2 ID at the MAC layer. be done.

<Radio Resource Allocation in Proximity Service>
From the perspective of the transmitting UE, a Proximity Service enabled UE (ProSe capable UE) can operate in two modes of resource allocation:

Mode 1 refers to a scheme in which the eNB schedules resource allocation, where the UE requests transmission resources from the eNB (or Release 10 relay node) and receives it from the eNodeB (or Release 10 relay node). nodes) schedule resources that UEs use to transmit 'direct' data and 'direct' control information (eg, scheduling assignments). The UE needs to be in RRC_CONNECTED state to send data. Specifically, the UE sends a scheduling request (D-SR (dedicated scheduling request) or random access) to the eNB, and then sends a buffer status report (BSR) in a normal way (next section “Transmission procedure in D2D communication” see also). Based on the BSR, the eNB can determine that the UE has data to transmit via ProSe direct communication and estimate the resources required for transmission.

Mode 2, on the other hand, refers to a scheme in which the UE selects resources autonomously, where the UE transmits 'direct' data and 'direct' control information (i.e. SA (Scheduling Assignment)). selects resources (time and frequency) for itself from the resource pool(s). One resource pool is e.g. defined by the contents of SIB18 (i.e. by the commTxPoolNormalCommon field) and this particular resource pool is broadcast in the cell and commonly available to all UEs still in RRC_IDLE state in that cell. is. In practice, an eNB can define up to 4 different instances of this pool (ie 4 resource pools for SA messages and 'direct' data transmission). However, the UE will always use the first resource pool defined in the list, even if multiple resource pools are configured for the UE.

Alternatively, the eNB may define a separate resource pool and signal it in SIB18 (ie by using the commTxPoolExceptional field) and the UE may use this resource pool in exceptional cases.

Which resource allocation mode the UE uses is configurable by the eNB. Furthermore, which resource allocation mode the UE uses for D2D data communication may also depend on the RRC state (i.e. RRC_IDLE or RRC_CONNECTED) and the UE coverage state (i.e. in-coverage or out-of-coverage). can. A UE is considered to be in coverage if it has a serving cell (ie the UE is in RRC_CONNECTED state or camped on a particular cell in RRC_IDLE state).

The following rules regarding resource allocation modes apply to the UE.
• If the UE is out of coverage, the UE can only use mode 2.
• If the UE is in coverage, the UE may use Mode 1 if the UE is configured by the eNB to be able to use Mode 1.
• If the UE is in coverage, the UE may use mode 2 if the UE is configured by the eNB to be able to use mode 2.
- When no exception conditions exist, the UE may change from Mode 1 to Mode 2 or from Mode 2 to Mode 1 only if the UE is configured by the eNB to change modes. When the UE is in coverage, the UE will only use the mode indicated by the eNB's configuration unless one of the exceptional cases occurs.
• The UE considers itself to be in an exception condition, eg while T311 or T301 is running.
• When exceptional cases occur, the UE is temporarily allowed to use Mode 2 even if it is configured to use Mode 1.

While within the coverage area of an E-UTRA cell, a user equipment performs ProSe direct communication transmissions on uplink carriers only on resources allocated by that cell (even if the carrier resources are : Universal Integrated Circuit Card).

For UEs in RRC_IDLE state, the eNB may choose one of the following options.
• The eNB provides a Mode 2 transmission resource pool in the SIB (System Information Block). UEs enabled for ProSe Direct Communication use these resources for ProSe Direct Communication in RRC_IDLE state.
• The eNB indicates in the SIB that it supports D2D but does not provide resources for ProSe direct communication. The UE needs to enter RRC_CONNECTED state to perform ProSe direct communication transmission.

For UEs in RRC_CONNECTED state, the following can be done.
• A UE that is in RRC_CONNECTED state and is authorized to perform a ProSe direct communication transmission indicates to the eNB that it wishes to perform a ProSe direct communication transmission when it needs to perform a ProSe direct communication transmission.
- The eNB checks if the UE in RRC_CONNECTED state is allowed for ProSe direct communication transmission using the UE context received from the MME.
• The eNB may configure, for a UE in RRC_CONNECTED state, a transmission resource pool for Mode 2 resource allocation schemes that can be used without restriction while the UE is in RRC_CONNECTED state through dedicated signaling. Alternatively, the eNB may configure, for a UE in RRC_CONNECTED state, a transmission resource pool for a Mode 2 resource allocation scheme that the UE can use only in exceptional cases, via dedicated signaling. If it can and is not an exceptional case, the UE follows Mode 1.

The resource pool for scheduling assignments when the UE is out of coverage can be configured as follows.
• The resource pool used for reception is pre-configured.
• The resource pool used for transmission is preconfigured.

The resource pool for scheduling assignments when the UE is in coverage can be set as follows.
• The resource pool used for reception is configured by the eNB via RRC (in dedicated or broadcast signaling).
• The resource pool used for transmission is configured by the eNB via RRC if Mode 2 resource allocation is used.
• The SCI (Sidelink Control Information) resource pool used for transmission (also called Scheduling Assignment (SA) resource pool) is not known to the UE when Mode 1 resource pools are used.
• If Mode 1 resource allocation is used, the eNB schedules specific resources for use in transmitting sidelink control information (scheduling allocation). The specific resources allocated by the eNB are within the resource pool for SCI reception provided to the UE.

FIG. 5 shows transmission/reception resource usage in overlay (LTE) and underlay (D2D) systems.

The eNodeB basically controls whether the UE applies Mode 1 or Mode 2 transmission. When a UE recognizes a resource on which it can transmit (or receive) D2D communication, it only uses the corresponding resource for corresponding transmission/reception in the current state of the art. For example, in FIG. 5, the D2D subframes are used only for the purpose of receiving or transmitting D2D signals. A UE, as a D2D device, operates in half-duplex mode and can therefore either receive or transmit D2D signals at any point in time. Similarly, other subframes shown in FIG. 5 may be used for LTE (overlay) transmission and/or reception.

<Transmission procedure in D2D communication>
D2D data transmission procedures differ depending on the resource allocation mode. As described above, for Mode 1, the eNB explicitly schedules scheduling assignments and resources for conveying D2D data after a corresponding request from the UE. Specifically, the eNB may inform the UE that D2D communication is basically allowed but no Mode 2 resources (ie resource pool) are provided. This notification can be done, for example, by exchanging a D2D Communication Interest Notification by the UE and a corresponding response, the D2D Communication Response, where the corresponding exemplary ProseCommConfig information element described above contains commTxPoolNormalCommon Not included, ie a UE wishing to initiate direct communication involving transmissions must request resource allocation from E-UTRAN for each individual transmission. In such a case, the UE must therefore request resources for each individual transmission, and the following is an exemplary sequence of steps for the request/allocation procedure for this Mode 1 resource allocation case.
- Step 1 UE sends SR (Scheduling Request) to eNB via PUCCH.
• Step 2 eNB grants uplink resources (for UE to send Buffer Status Report (BSR)) via PDCCH scrambled by C-RNTI.
• Step 3 UE sends D2D BSR over PUSCH indicating buffer status.
• Step 4 eNB allocates D2D resources (for UE to send data) via PDCCH scrambled by D2D-RNTI.
• Step 5 The D2D transmitting UE transmits SA/D2D data according to the grant received in step 4.

Scheduling Assignment (SA) (also called SCI (Sidelink Control Information)) specifies control information (e.g. pointer to time-frequency resource for transmitting corresponding D2D data, modulation and coding scheme, group destination ID). It is a compact (low payload) message containing The SCI carries sidelink scheduling information for one (ProSE) destination ID. The SA (SCI) content basically follows the grant received in step 4 above. The contents of the D2D grant and SA (ie the contents of the SCI) are specifically specified in 5.4. Section 3, which is incorporated herein by reference.

In contrast, for Mode 2 resource allocation, steps 1 to 4 above are basically unnecessary, and the UE is configured by the eNB for scheduling assignment (SA) and resources for transmitting D2D data. and autonomously selects from the provided transmission resource pool(s).

FIG. 6 exemplarily shows the scheduling assignment and D2D data transmission for two UEs (UE-A and UE-B). The resources for sending scheduling assignments are periodic, and the resources used for sending D2D data are indicated by the corresponding scheduling assignments.

FIG. 7 shows D2D communication timing for mode 2 (autonomous scheduling) during one SA/data period (also known as SC period (sidelink control period)). FIG. 8 shows D2D communication timing for Mode 1 (eNB schedules allocation) during one SA/data period. An SC period is a window of time that consists of a scheduling assignment and its corresponding transmission of data. As can be seen from FIG. 7, the UE transmits the scheduling assignment using the transmission pool resource for scheduling assignment in mode 2 (SA_Mode2_Tx_pool) after the SA offset time. After the first transmission of SA, the same SA message is retransmitted, for example, three times. The UE then starts the D2D data transmission (or 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). ). A single D2D data transmission of a MAC PDU consists of its first transmission and several retransmissions. In the illustration of FIG. 7 (and FIG. 8), 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)) basically represents the transmission of a MAC PDU (first transmission) and its retransmissions (second, third, and fourth define the timing of transmission).

During one SA/data period, the UE may transmit multiple transport blocks (only one per subframe (TTI), ie in sequence), but to only one ProSe destination group. Furthermore, the retransmission of one transport block must be completed before the first transmission of the next transport block is started, i.e. only one HARQ process is used for multiple transport block transmissions. be done.

As is evident from FIG. 8, for the eNB-scheduled resource allocation mode (mode 1), the D2D data transmission (or more specifically the T-RPT pattern/bitmap) is allocated within the SA resource pool It starts in the next UL subframe after the last iteration of SA transmission. As already explained in FIG. 7, the T-RPT bitmap for Mode 1 (Transmission Time Resource Pattern (T-RPT)) is basically the transmission of a MAC PDU (first transmission) and its retransmissions (2 3rd, 3rd and 4th transmissions).

<ProSe Network Architecture and ProSe Entities>
FIG. 9 shows a high-level exemplary architecture for the non-roaming case, including different ProSe applications in UE A and UE B, ProSe application servers and ProSe functions in the network. The example architecture of FIG. 9 is taken from Non-Patent Document 8, section 4.2 “Architectural Reference Model” (incorporated herein by reference).

Functional Entities are presented and described in detail in Non-Patent Document 8, Section 4.4 "Functional Entities" (incorporated herein by reference). A ProSe Function is a logical function used for network-related operations required of ProSe, and plays a different role in each aspect of ProSe. The ProSe function is part of 3GPP's EPC (Evolved Packet Core) and provides all relevant network services such as authorization, authentication and data processing related to proximity services. In ProSe Direct Discovery and Direct Communication, a UE can obtain a unique ProSe UE identity, other configuration information, and authentication from ProSe functions through a 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: Direct Provision Function (DPF), Direct Discovery Name Management Function (DPF), and EPC level. Discovery function (EPC-level Discovery Function). DPF is used to provide the UE with the necessary parameters for the purpose of using ProSe Direct Discovery and ProSe Direct Communication.

The term "UE" used in this context means a ProSe capable UE that supports, for example, the following ProSe features.
Exchanging ProSe control information between a ProSe capable UE and a ProSe function through the PC3 reference point A procedure for open ProSe direct discovery of another ProSe capable UE through the PC5 reference point One-to-many ProSe through the PC5 reference point Procedures for direct communication • Procedures for operating as a ProSe UE-network repeater. Remote UEs communicate with the ProSe UE-Network Repeater through the PC5 reference point. The ProSe UE-Network Repeater uses Layer 3 packet forwarding.
Exchanging control information between ProSe UEs over a PC5 reference point, e.g. for UE-network repeater detection and ProSe direct discovery ProSe control information over a PC3 reference point between another ProSe capable UE and a ProSe function to replace. In the case of ProSe UE-Network Relay, the remote UE sends 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, radio resource parameters). These parameters can be preconfigured at the UE or provided to the ProSe function in the network by signaling through the PC3 reference point when in coverage.

The ProSe Application Server supports storage of EPC ProSe User IDs and ProSe Function IDs, and mapping of application layer User IDs and EPC ProSe User IDs. A ProSe Application Server (AS) is an entity outside the scope of 3GPP. ProSe applications in the UE communicate 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.

<UE coverage state in D2D>
As already mentioned above, the resource allocation method in D2D communication depends not only on the RRC state (ie RRC_IDLE and RRC_CONNECTED) but also on the coverage state of the UE (ie in-coverage, out-of-coverage). A UE is considered in coverage if it has a serving cell (ie the UE is in RRC_CONNECTED state or the UE is camped on a cell in RRC_IDLE state).

The two coverage states described so far, namely in-coverage (IC) and out-of-coverage (OOC), are further differentiated into sub-states in D2D. Figure 10 shows four different states with which a D2D UE can be associated, which can be summarized as follows.
• State 1: UE1 has uplink coverage and downlink coverage. In this state, the network controls each D2D communication session. Further, the network configures whether UE1 should use resource allocation mode 1 or resource allocation mode 2.
• State 2: UE2 has downlink coverage but no uplink coverage (ie DL coverage only). The network broadcasts a (contention-based) resource pool. In this state, the transmitting UE selects resources to use for SA and data from a resource pool configured by the network. In such a state, only resource allocation according to mode 2 is possible in D2D communication.
• State 3: Strictly speaking, UE3 is already considered out of coverage (OOC) because it has no uplink and downlink coverage. However, UE3 is also within the coverage of some UEs (eg UE1) which are themselves within the coverage of the cell, ie these UEs can also be referred to as CP relay UEs. Therefore, the region of state 3 UEs in FIG. 10 can be referred to as the CP UE relay coverage region. UEs in this State 3 are also referred to as out-of-coverage (OOC) State 3 UEs. In this state, the UE receives some cell-specific information, which is sent by the eNB (SIB) and out-of-coverage (SIB) by the CP UE relay UE in the cell's coverage via PD2DSCH. OOC) State 3 Transferred to the UE. A network-controlled (contention-based) resource pool is signaled by the PD2DSCH.
• State 4: UE4 is out of coverage and does not receive PD2DSCH from another UE that is in coverage of the cell. In this state (also referred to as State 4 Out of Coverage (OOC)), the transmitting UE selects resources to use for data transmission from a pre-configured resource pool.

The reason for distinguishing between State 3 Out-of-Coverage (OOC) and State 4 Out-of-Coverage (OOC) is primarily to avoid possible strong interference between D2D transmissions from out-of-coverage devices and legacy E-UTRA transmissions. It is for A D2D capable UE typically has a pre-configured resource pool for transmission of D2D SAs and data for use when out of coverage. When these out-of-coverage UEs transmit near the edge of the cell using these pre-configured resource pools, the interference between their D2D transmissions and the in-coverage legacy transmissions can cause intra-cell communications. may adversely affect If in-coverage D2D capable UEs transfer D2D resource pool configuration to these out-of-coverage devices near the cell boundary, the out-of-coverage UEs direct their transmissions to these resources designated by the eNodeB. can be limited, thus minimizing interference with legacy transmissions within the coverage. Therefore, RAN1 has introduced a mechanism for UEs within its coverage to transfer resource pool information and other D2D related configurations to devices immediately outside the coverage area (UEs in state 3).

A physical D2D Synchronization Channel (PD2DSCH) is used to convey this information about the in-coverage D2D resource pool to UEs located nearby in the network, thus coordinating the resource pools within the network's vicinity.

<LCP procedure for D2D (sidelink) logical channel>
The LCP procedure in D2D is different from the LCP procedure shown above for "normal" LTE data. The following information is from Non-Patent Document 5 (current version 12.5.0) describing LCP in ProSe, section 5.14.1.3.1, which is incorporated herein by reference in its entirety. ).

The UE performs the following logical channel prioritization procedure when a new transmission is performed.
• The UE (eg MAC entity) allocates resources to sidelink logical channels according to the following rules:
- The UE should not split the RLC SDU (or partially transmitted SDU) if the entire SDU (or partially transmitted SDU) fits in the remaining resources.
- When the UE splits the RLC SDUs from the sidelink logical channels, it maximizes the size of the segments to fill the grant as much as possible.
- The UE should maximize data transmission.
- When the UE has data available for transmission, the UE does not transmit padding only, given a sidelink grant size equal to or greater than 10 bytes.

Note: The above rule implies that the order in which the sidelink logical channels are processed is left to the UE implementation.

In general, the MAC layer only considers logical channels that have the same pair of source and destination Layer 2 IDs in one PDU, i. Only the logical channels of the destination group are considered, ie basically the UE selects the ProSe destination group during the LCP procedure. Furthermore, in Release 12, during one SA/data period, a D2D transmitting UE can only send data to one ProSe destination group.

All D2D (sidelink) logical channels (e.g. STCH (Sidelink Traffic CHannel: sidelink traffic channel)) are assigned to the same logical channel group (LCG) with LCGID set to "11" (Non-Patent Document 5 5.14.1.4 Buffer Status Reporting). In Release 12, there is no prioritization mechanism for D2D (sidelink) logical channels/groups. Essentially, all sidelink logical channels have the same priority from the UE's point of view, ie the order in which the sidelink logical channels are processed is left to the UE implementation.

For illustrative purposes only, consider the following exemplary scenario. There are three ProSe logical channels LCH#1, LCH#2 and LCH#3 established in the user equipment, all three associated with the same ProSe LCG (eg "11"). For illustrative purposes, assume that LCH#1 and LCH#2 are assigned to ProSe destination group 1 and LCH#3 is assigned to ProSe destination group 2. FIG. This scenario is illustrated in FIG.

<Buffer status report in ProSe>
Buffer status reporting has also been adapted to ProSe and is now available in Non-Patent Document 5 (version 12.5.0), section 5.14.1.4 "Buffer Status Reporting" (incorporated herein by reference). is defined as

The (D2D) sidelink buffer status reporting procedure is used to provide the serving eNB with information on the amount of sidelink data available for transmission in the UE's sidelink buffer. RRC controls sidelink BSR reporting by setting two timers Periodic-ProseBSR-Timer and RetxProseBSR-Timer. Each sidelink logical channel (STCH) is assigned to an LCG with LCGID set to '11' and belongs to the ProSe destination group.

A sidelink buffer status report (BSR) is triggered when a number of specific events occur (specified in detail in Section 5.14.1.4 of Non-Patent Document 5).

Additionally, Section 6.1.3.1a of Non-Patent Document 5 (version 12.5.0) (incorporated herein by reference) describes the ProSe BSR MAC control element and its corresponding content as: It is defined as follows. The ProSe Buffer Status Report (BSR) MAC control element consists of one group index field, one LCG ID field, and one corresponding buffer size field per reported D2D destination group. More specifically, the following fields are defined for each included ProSe Destination Group.
• Group Index: The Group Index field identifies the ProSe destination group. The length of this field is 4 bits. The value is set to the index of the destination identification reported in destinationInfoList.
• LCG ID: The Logical Channel Group ID field identifies the group(s) of logical channels for which buffer status is reported. The length of the field is 2 bits and is set to '11'.
Buffer Size: The Buffer Size field identifies the total amount of data available across all logical channels of the ProSe destination group after all TTI's MAC PDUs have been built. The amount of data is indicated in bytes.
• R: Reserved bit, set to '0'.

FIG. 11 shows the MAC control element of ProSe BSR for an even number N (number of ProSe destination groups) (taken from Section 6.1.3.1a of Non-Patent Document 5).

As explained above, the transmission scheme for inter-device communication is quite different from the normal LTE scheme, including the use of ProSe destination groups to identify data content. Some of the currently defined mechanisms are rather inefficient.

3GPP TS 36.211, “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation (Release 8)” 3GPP TS 36.213 3GPP TS 36.212, “Multiplexing and channel coding” LTE - The UMTS Long Term Evolution - From Theory to Practice, Edited by Stefanie Sesia, Issam Toufik, Matthew Baker 3GPP TS 36.321 3GPP TR 36.843 3GPP TS 36.300 TS 23.303

Exemplary non-limiting embodiments allocate radio resources for a transmitting user equipment to perform direct communication transmissions over direct sidelink connections to one or more receiving user equipments. An improved method is provided. The independent claims provide non-limiting exemplary embodiments of the invention. Advantageous embodiments are subject matter of the dependent claims.

According to some aspects, particularly (but not limited to) a scenario in which data destined for more than one sidelink destination group at the transmitting user equipment is available for transmission. improves the step of performing a direct communication transmission.

A main aspect of the present invention is to allocate radio resources to a transmitting user equipment for performing direct communication transmissions over a direct sidelink connection to one or more receiving user equipments in a communication system. a radio base station for providing at least two sidelink grants to said transmitting user equipment such that said transmitting user equipment is capable of receiving at least two sidelink grants covering direct communication transmissions performed within the same transmission control period; two sidelink grant processes are provided, each one of the at least two sidelink grant processes is associated with identification information and can be associated with one sidelink grant, the radio base station
- a processor configured to generate a sidelink grant and associate the generated sidelink grant with one sidelink grant process of the at least two sidelink grant processes;
- the processor is configured to generate a sidelink scheduling message including identification of the one sidelink grant process associated with the sidelink grant;
the processor;
- a transmitter configured to transmit the generated sidelink scheduling message to the transmitting user equipment;
A wireless base station equipped with

According to a first aspect, in order to allow the user equipment to handle several sidelink grants essentially simultaneously, in other words the user equipment performs several direct communication transmissions essentially simultaneously (e.g. the same transmission In order to be able to transmit within a controlled period), we introduce a new concept of sidelink grant process. Accordingly, each direct communication transmission can be configured to transmit data for the same or different sidelink destination groups.

In the prior art, sidelink grants are overwritten by the next received sidelink grant. In contrast, according to this first aspect, by having multiple sidelink grant processes available in the UE, it is possible to allocate different sidelink grants to different sidelink grant processes. i.e. a sidelink grant can still be overwritten (if a new sidelink grant for the same sidelink grant process is received), but the UE can have several valid sidelink grants at the same time (no need to overwrite). do not have). A sidelink grant can be uniquely associated with one of the processes by the corresponding ID of each sidelink grant process. Furthermore, one sidelink grant process is associated with only one (valid) sidelink grant. When obtaining a further sidelink grant associated with the same sidelink grant process, the previous sidelink grant is overwritten as already explained.

Thus, the UE may, in each of the sidelink grant processes and their associated sidelink grants, for sending direct communication transmissions including the transmission of sidelink control information and data destined for one sidelink destination group. Radio resources are allocated according to respective sidelink grants.

Thus, if data of different sidelink destination groups are available for transmission within the user equipment, the user equipment transmits data of different sidelink destination groups using each of the available sidelink grants. can be determined. Thus, the transmitting user equipment performs essentially one direct communication transmission per sidelink grant process at the same time (i.e. within the same transmission control period), where each direct communication transmission serves a different sidelink destination group. Can contain data to be sent to. In one implementation of the first aspect, radio resources for multiple direct communication transmissions performed within the same transmission control period do not overlap in the time domain. Time division is used in direct communication transmissions.

Resource starvation of one sidelink destination group can be avoided according to the first aspect. Furthermore, there is no change in the transmission scheme from the receiving user equipment's point of view, since the transmitting user equipment only sends data for one sidelink destination group per direct communication transmission (i.e. per sidelink grant process). is. Therefore, the sidelink control information can remain the same. In one implementation of the first aspect, the step of determining the sidelink destination group(s) to which data should be sent comprises: for all obtained sidelink grant(s) To determine the sidelink destination group, it can be performed by the transmitting user equipment using a common logical channel prioritization procedure, or the transmitting user equipment can perform individual channel allocation for each sidelink grant. Use a logical channel prioritization procedure.

The principle of the first aspect is that both resource allocation methods (i.e. receiving the corresponding sidelink grant from the radio base station after the transmitting user equipment requests it and the transmitting user equipment (one or more ) autonomous selection of sidelink grants from the appropriate transmit radio resource pool). When the radio base station transmits a scheduling message containing a sidelink grant to the transmitting user equipment, the sidelink scheduling message contains (e.g. information about the content of the scheduling control information to be transmitted by the transmitting user equipment and the scheduling Besides comprising information about radio resources to be used for transmission of control information and data, the sidelink grant process with which the sidelink grant should be associated can also be identified. Based on this, the transmitting user equipment can associate the received sidelink grant with the intended sidelink grant process.

According to a second aspect, direct communication transmission is improved by allowing the scheduling assignment (sidelink control information) transmitted by the transmitting user equipment to essentially identify multiple sidelink destination groups. . Thus, data destined for multiple sidelink destination groups is available for transmission within the transmitting user equipment, and furthermore, the transmitting user equipment has available sidelinks for performing direct communication transmissions. Assume that you have a grant. The transmitting user equipment determines at least two sidelink destination groups from among the plurality of sidelink destination groups to convey data in the direct communication transmission. The sidelink control information associated with the direct communication transmission transmits the determined at least two sidelink destination groups and sidelink control information and corresponding data destined for the determined at least two sidelink destination groups. radio resources allocated for; Thus, the transmitting user equipment performs a direct communication transmission capable of carrying data for multiple sidelink destination groups.

According to one implementation of the second aspect, the sidelink control information message includes one ID per sidelink destination group.

According to an alternative implementation of the second aspect, the sidelink control information message includes one sidelink ID associated with multiple sidelink destination groups. In this alternative implementation, a mapping function is introduced to establish a correspondence between different sidelink IDs and corresponding sidelink destination groups, and corresponding information about this correspondence is sent to the sending user equipment and the receiving user equipment. must be provided for both side-user equipment. After the transmitting user equipment determines the sidelink destination group to which data should be conveyed by direct communication transmission, the transmitting user equipment assigns the corresponding sidelink ID to this correspondence so that the sidelink ID is associated with the determined sidelink destination group. Seek based on. The sidelink IDs can then be included in the corresponding sidelink control information in place of the various IDs of the sidelink destination group. On the receiving side, the receiving UE can determine the sidelink destination group to which the sidelink ID refers, based on this information about the correspondence as well.

The principle of the second aspect is that both resource allocation methods (i.e. receiving the corresponding sidelink grant from the radio base station after the transmitting user equipment requests it and the transmitting user equipment (one or more ) autonomous selection of sidelink grants from the appropriate transmit radio resource pool).

Thus, in one general first aspect, the technology disclosed herein enables a transmitting user equipment in a communication system to A method for allocating radio resources for performing direct communication transmissions. At least two sidelink grant processes are provided to the transmitting user equipment such that the transmitting user equipment can handle at least two sidelink grants within the same transmission control period. Each one of the at least two sidelink grant processes is associated with identification information and can be associated with one sidelink grant. At least two sidelink grants are obtained, each sidelink grant being associated with one of the at least two sidelink grant processes by the transmitting user equipment. Further, in each of the at least two sidelink grants, radio resources for performing direct communication transmission of sidelink control information and data over the direct sidelink connection are allocated by the transmitting user equipment according to the respective sidelink grants. . Thus, the transmitting user equipment performs a direct communication transmission within the same transmission control period for each sidelink grant process that has a correspondingly-associated sidelink grant.

Thus, in one general first aspect, the technology disclosed herein enables a transmitting user equipment in a communication system to Another method of allocating radio resources for performing direct communication transmissions is provided. At the transmitting user equipment, data destined for multiple sidelink destination groups is available for transmission. A sidelink grant used for direct communication transmission is available to the sending user equipment. The transmitting user equipment determines at least two sidelink destination groups from the plurality of sidelink destination groups as destinations for direct communication transmissions. The transmitting UE allocates radio resources used for direct communication transmissions according to the available sidelink grants. The transmitting UE generates a sidelink control information message identifying the determined at least two sidelink destination groups and the allocated radio resources. The transmitting UE performs direct communication transmission of the generated sidelink control information messages and data destined for the determined at least two sidelink destination groups over the direct sidelink connection.

Thus, in one general first aspect, the technology disclosed herein performs direct communication transmission over a direct sidelink connection to one or more receiving user equipment in a communication system. to provide a user equipment that At least two sidelink grant processes are provided to the transmitting user equipment such that the transmitting user equipment can handle at least two sidelink grants within the same transmission control period. Each one of the at least two sidelink grant processes is associated with identification information and can be associated with one sidelink grant. A processor of the transmitting user equipment obtains at least two sidelink grants and associates each of the obtained at least two sidelink grants with one of the at least two sidelink grant processes. For each of the at least two sidelink grants, the processor allocates radio resources for performing direct communication transmission of sidelink control information and data over the direct sidelink connection according to the respective sidelink grant. Thus, the transmitting user equipment performs a direct communication transmission within the same transmission control period for each sidelink grant process that has a correspondingly associated sidelink grant.

Thus, in one general first aspect, the technology disclosed herein performs direct communication transmission over a direct sidelink connection to one or more receiving user equipment in a communication system. provide another user equipment that The transmitting user equipment comprises a buffer that stores data available for transmission and destined for a plurality of sidelink destination groups. A sidelink grant used for direct communication transmission is available to the sending user equipment. A processor of the transmitting user equipment determines at least two sidelink destination groups from the plurality of sidelink destination groups as destinations for the direct communication transmission. A processor allocates radio resources used for direct communication transmissions according to available sidelink grants. The processor generates a sidelink control information message identifying the determined at least two sidelink destination groups and the allocated radio resources. The transmitting UE's processor and transmitter perform direct communication transmission of the generated sidelink control information messages and data destined for the determined at least two sidelink destination groups over the direct sidelink connection.

Thus, in one general first aspect, the technology disclosed herein enables a transmitting user equipment in a communication system to A radio base station for allocating radio resources to a transmitting user equipment for performing direct communication transmissions. At least two sidelink grant processes are provided to the transmitting user equipment such that the transmitting user equipment can handle at least two sidelink grants within the same transmission control period. Each one of the at least two sidelink grant processes is associated with identification information and can be associated with one sidelink grant. A radio base station processor generates a sidelink grant and associates the generated sidelink grant with one of at least two sidelink grant processes. A processor generates a sidelink scheduling message including identification information of one sidelink grant process associated with the sidelink grant. The radio base station transmitter transmits the generated sidelink scheduling message to the transmitting user equipment.

Further benefits and advantages of the disclosed embodiments will be apparent from the specification and drawings. These benefits and/or advantages may be provided individually by various embodiments and features of the disclosure herein and by the drawings, and all in order to obtain one or more of these benefits and/or advantages. need not be set.

These general and specific aspects can be implemented using systems, methods, computer programs, or any combination thereof.

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

1 shows an exemplary architecture of a 3GPP LTE system; 3 shows an exemplary downlink resource grid for downlink slots of subframes defined in 3GPP LTE (Release 8/9). Fig. 3 schematically shows a PC5 interface for direct discovery between devices; Figure 2 schematically shows a wireless protocol stack for ProSe direct discovery; Fig. 2 shows transmission/reception resource usage in overlay (LTE) and underlay (D2D) systems; Figure 3 shows scheduling assignment (SA) and D2D data transmission for two UEs. Fig. 3 shows the D2D communication timing in mode 2, where the UE autonomously schedules; 1 shows D2D communication timing in scheduling mode 1 scheduled by an eNB. Fig. 3 shows an exemplary model of ProSe's architecture in a non-roaming scenario; Fig. 4 shows cell coverage for four different states with which a D2D UE may be associated; Figure 3 shows the ProSe Buffer Status Report MAC control element defined in the standard; FIG. 4 shows the correspondence between ProSe Logical Channels, ProSe LCGs and ProSe Destination Groups in an exemplary scenario; FIG. 4 shows a sequence diagram of UE behavior at the transmitting side according to an implementation of the first embodiment; FIG. FIG. 4 illustrates D2D communication timing for two eNB-scheduled D2D transmissions according to an implementation of the first embodiment; FIG. FIG. 4 illustrates D2D communication timing for two UE autonomously scheduled D2D transmissions according to an implementation of the first embodiment; FIG. FIG. 12 shows a sequence diagram of UE behavior at the transmitting side according to an implementation of the second embodiment; FIG. FIG. 12 illustrates D2D communication timing in an eNB-scheduled D2D transmission carrying data for several sidelink destination groups, according to an implementation of the second embodiment; FIG.

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

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

The term "direct communication transmission" as used in the claims and this application is understood broadly as a direct (i.e. not via a radio base station (e.g. eNB)) transmission between two user equipments. want to be A direct communication transmission is thus carried out through a “direct sidelink connection”, which is the term used for a connection established directly between two user equipments. For example, 3GPP uses the terminology D2D (device-to-device) communication, or ProSe communication, or sidelink communication. The term "direct sidelink connection" as used in the claims and this application shall be understood broadly and in the context of 3GPP can be understood as the PC5 interface described in the Background section.

The term "sidelink grant process" as used in the claims and this application should be understood broadly as a process available in the user equipment with which a sidelink grant can be associated. Illustratively, the sidelink grant process can also be understood broadly as a memory area in the user equipment in which the sidelink grant or sidelink grant information is stored and maintained. Each memory area is managed by the user equipment (e.g., storing sidelink grant information, clearing, overwriting stored sidelink grant information with newly received sidelink grant information).

The term "transmission control period" as used in the claims and this application should be broadly understood as a period during which the user equipment performs scheduling assignments (sidelink control information) and corresponding data transmissions. In other words, the "transmission control period" can also be understood as a period during which the sidelink grant is valid. As currently standardized in the 3GPP environment, the “transmission control period” can be understood as the SA/data period or the SC (Sidelink Control) period.

The term "ProSe destination group" or "sidelink destination group" as used in the claims and the rest of this application refers to, for example, the Source Layer 2 ID and the Destination Layer 2 ID defined in 3GPP LTE. It can be understood as a pair of IDs.

The expressions "obtain (sidelink) grant", "have (sidelink) grant available", "receive (sidelink) grant", and similar expressions are used from the radio base station responsible for (Sidelink) grant by acquiring or receiving a (sidelink) grant (i.e. Mode 1) or by the UE autonomously selecting resources for the grant from the appropriate transmission resource pool(s) It should be broadly understood to mean acquiring itself (ie mode 2) (ie the UE receives the grant internally).

Background on the currently standardized transmission schemes used for D2D communication, both those associated with Mode 1 (i.e. eNB-scheduled) and those associated with Mode 2 (autonomous scheduling): Described in the technical section. In particular, currently the UE can only have one (valid) sidelink grant (SL grant) per sidelink control period (SC period). In mode 1, even if the eNB issues several grants to the UE, the UE only considers the last received grant as a valid grant and the previously received (one or more ) override the SL grant. Therefore, the UE can only send one scheduling assignment per SC period since there is only one SL grant available per SC period. On the other hand, currently a UE can only transmit data for one ProSe destination group per scheduling assignment, ie scheduling control information (SCI). More specifically, in the PDU(s) associated with one SCI, the UE only considers logical channels with the same pair of source and destination Layer 2 IDs. This currently standardized D2D transmission scheme has several drawbacks.

If the UE has data for more than one ProSe destination group in its buffer, the UE can only send data for one ProSe destination group in one SC period, thus the remaining (one or multiple) ProSe destination group data is typically delayed by at least one further SC period. Depending on the configured SC period and the number of SC periods required to transmit the complete data for one ProSe destination group, this delay can be quite large. This is true even if the resources available for transmission are sufficient to transmit more data than the ProSe destination group that is processed first. More specifically, the eNB may allocate more D2D transmission resources (via SL grants) than the UE needs, i.e. the UE has only one ProSe It does not have enough data for the destination group in its buffer. This situation can occur, for example, when the buffer status information received at the eNB side is not accurate or the information is out of date. In this case, some of the allocated resources remain unused because these resources cannot be used to transmit data for another ProSe destination group.

The inventors have conceived the following exemplary embodiments to alleviate the problems described above.

Some of the embodiments are implemented within broad specifications given by the 3GPP standards, some of which are described in the Background section, and particularly important features associated with various embodiments are described below. added to It should be noted that although these embodiments can be advantageously used in mobile communication systems such as, for example, 3GPP LTE-A (Release 10/11/12/13) as described in the background section, these embodiments is not limited to use with this particular exemplary communication network.

The following description should not be understood as limiting the scope of the present disclosure, but merely as examples of embodiments for a better understanding of the present disclosure. Those skilled in the art should recognize that the general principles of the disclosure, as recited in the claims, can be applied to a variety of scenarios and in ways not explicitly described herein. be. Accordingly, the following scenarios envisioned for purposes of describing various embodiments are not intended to limit the invention and its embodiments to such scenarios.

<First embodiment>
A first embodiment for solving the above problem will be described in detail below. An implementation of the first embodiment is described with respect to FIGS. 13-15.

For purposes of explanation, some assumptions are made, but these assumptions are not intended to limit the scope of the embodiments. By way of example, user equipment (ProSe capable UEs) enabled to perform ProSe communication (i.e. direct D2D transmission between UEs without going through an eNodeB) is assumed. Furthermore, it is assumed that the UE has data available for transmission destined for multiple sidelink destination groups (i.e. ProSe destination groups), provided that the improved direct communication transmission according to the first embodiment is , even if only one sidelink destination group's data is available for transmission at the UE.

The first embodiment improves direct communication transmission by introducing the concept of sidelink grant process(es) that allows one-to-one allocation of sidelink grant(s) within the UE. do. In other words, the UE can handle multiple sidelink grants by running a sidelink grant process corresponding to each sidelink grant. A sidelink grant process can be addressed through the use of corresponding identification information (hereinafter exemplarily referred to as a sidelink grant process ID), which uniquely identifies the sidelink grant to a particular sidelink grant process. can be assigned

In currently standardized systems, only one sidelink grant can be handled by the UE at the same time (further received sidelink grant(s) will overwrite the previous sidelink grant, thus There is only one valid sidelink grant within one SC period), whereas the first embodiment allows the UE to receive two or more Improve D2D communication by being able to have a valid sidelink grant. In other words, a UE operating according to the first embodiment is allowed to have one valid sidelink grant per sidelink grant process, thus the number of valid sidelink grants possible within the SC period at the UE is limited by the maximum number of sidelink grant processes that the UE can operate. Therefore, when a UE obtains a sidelink grant addressed to a sidelink grant process that already has a sidelink grant, it overwrites the old sidelink grant with the newly obtained sidelink grant (in the currently standardized system resemble).

According to one implementation of the first embodiment, the UE is allowed to have, for example, at most two sidelink grant processes so that the UE can handle two different sidelink grants simultaneously. (so the UE has two valid sidelink grants in the SC period). Therefore, the sidelink grant process ID can have a size of 1 bit in order to be able to distinguish between the two sidelink grant processes. In another implementation of the first embodiment, a larger number (e.g., 4, or 8, etc.) sidelink grant processes can be activated in the UE, which allows the UE to support even more sidelink Grants can be handled simultaneously. However, the corresponding sidelink grant process ID has a size of more bits to allow different sidelink grant processes to be distinguished. For example, 2 bits for a total of 4 sidelink grant processes, 3 bits for a total of 8 sidelink grant processes, and so on.

The maximum number of sidelink grant processes handled by the UE can be configured, for example, by RRC, or can be pre-determined (eg, determined in the corresponding 3GPP standard).

Overall, the UE performs D2D transmissions in each sidelink grant process within the same SC period, respectively according to already standardized concepts for performing D2D transmissions, e.g., described in the background art section. Specifically, for each sidelink grant available to the UE (i.e. in each sidelink grant process), the UE determines one sidelink destination group and includes data destined for the determined sidelink destination group. Generate the corresponding transport block. Radio resources for D2D transmission are allocated according to respective sidelink grants. For each sidelink grant available to the UE (i.e. in each sidelink grant process), the UE has a corresponding sidelink grant that identifies the sidelink destination group and the radio resources allocated for the corresponding D2D transmission. Generate control information and perform D2D transmission of sidelink control information and corresponding data for each sidelink grant (process) using the allocated radio resources of the respective sidelink grant.

Details of these steps for performing D2D transmission are omitted here, but instead refer to the corresponding sections in the Background section of this application.

The above-described principle underlying the first embodiment entails various advantages. In this respect, already established procedures can be reused without modification. For example, the same SCI format 0 can be used for the purpose of transmitting sidelink control information, since no additional information needs to be conveyed. Furthermore, since the D2D transmission in each sidelink grant process remains unchanged when compared to the currently standardized D2D transmission, the receiving UE can perform according to the first embodiment in one sidelink grant process and D2D transmissions performed according to current standards (no real need to do so). Therefore, there is no need to adapt the behavior of the receiving UE.

Moreover, in the first embodiment, more data can be transmitted within the SC period, thus increasing the data rate of D2D transmission.

Additionally, in the first embodiment, data destined for several sidelink destination groups can be sent to the same SC period, for example, by selecting different sidelink destination groups in each of the various sidelink grant processes. can be sent within Thus, starvation of resources for a particular sidelink destination group can be avoided.

So far, we have generally assumed that the UE has several sidelink grants available, and have not paid attention to how the UE initially obtained these sidelink grants. . Indeed, in the operation of the UE according to the principles of the first embodiment, the UE obtained the sidelink grant according to mode 1 (scheduled by the eNB) or according to mode 2 (autonomous selection by the UE). It doesn't matter. In other words, the first embodiment applies when the sidelink grant is obtained according to mode 1 or according to mode 2, respectively. In addition, one sidelink grant can be scheduled by mode 1 and another sidelink grant can be scheduled by mode 2.

For Mode 1, one or more of the A sidelink grant is received from an eNB. In Mode 1, each sidelink grant is received in a corresponding sidelink scheduling message sent by the eNB to the UE, which further describes the sidelink grant process in which the sidelink grant is assigned by the UE. can be identified. For example, the corresponding sidelink grant process ID mentioned above may be included by the eNB in the corresponding field of the sidelink scheduling message, in which case the UE is responsible for each sidelink grant to which the received sidelink grant should be assigned. A process can be identified using this sidelink grant process ID.

According to one implementation of the first embodiment, a new DCI format (illustratively referred to as DCI format 5a) may be introduced in this respect, which at least contains side-by-side data in the corresponding field. Contains the link grant process ID. The number of bits in such new field containing the sidelink grant process ID depends on the maximum total number of sidelink grant processes available to the UE. For example, the new sidelink grant process ID field may have 2 bits, allowing a total of 4 sidelink grant processes to be distinguished.

In the new DCI format 5a, at least one or all of the following additional possible fields can also be expected.
- Resources for PSCCH - TPC commands for PSCCH and PSSCH - The following fields of SCI format 0: Frequency hopping flags Resource block allocation and hopping resource allocation Time resource pattern

These other possible fields in the new DCI format 5a correspond to the same fields already standardized in DCI format 5 (5.3.3 .1.9).

As mentioned above, in the prior art, the sidelink scheduling message used to send sidelink grants is DCI format 5 (see Background section). Section 5.3.3.1.9 of Non-Patent Document 3 (current version 12.4.0) currently defines DCI format 5 as follows.
"If the number of information bits in format 5 mapped to a given search space is less than the payload size of format 0 for scheduling the same serving cell, then the payload size of format 5 is the padding bits appended to format 0. Add zeros to format 5 until it equals the payload size of format 0, including

As is clear from this definition, to facilitate blind decoding, DCI format 5 is appended with "zero (0)" so that the payload size of DCI format 5 is equal to the payload size of DCI format 0. . According to a further implementation of the first embodiment, instead of introducing a new DCI, these padding bits (i.e. "zero (0)") can be reused for the purpose of indicating the sidelink grant process ID. can.

Alternatively, there is another way to convey the new sidelink grant process ID field in the sidelink grant. In particular, some bits of any existing DCI (eg DCI format 5) can be redefined for this purpose. In this case, some predefined codepoint(s) of at least one field conveyed in this DCI, or a combination of predefined codepoints of several fields, is required. , this code point or combination of code points indicates that the remaining bits in that DCI are interpreted differently (ie, to indicate the sidelink grant process ID).

As mentioned above, the UE may perform several D2D transmissions within the same sidelink control period (eg, one per sidelink grant process). Various D2D transmissions performed by a UE within the same sidelink control period generally do not overlap in the time domain (ie the UE performs D2D transmissions in different subframes). In particular, radio resources used for transmitting sidelink control information messages obtained from corresponding transmission pools do not overlap in time. Similarly, the T-RPT pattern, which defines the timing of the first transmission of a MAC PDU and its retransmissions, is chosen accordingly to avoid overlapping the data transmissions of the two D2D transmissions in time. The same applies to transmission resources for scheduling control information (SCI), ie SCI transmissions of different sidelink grant processes do not overlap in time.

For D2D transmissions scheduled in Mode 1, the eNodeB determines non-overlapping T-RPT patterns and transmission resources for SCI and informs these to the UE in respective sidelink scheduling messages. In contrast, for D2D transmissions scheduled in mode 2, when selecting resources from the corresponding pool, non-overlapping radio resources for the various D2D transmissions (i.e. SCI and data) are selected such that: The UE itself will handle it.

Alternatively, defining e.g. can be done. SA_offset is a parameter that defines the start of the D2D transmission (see Figures 7 and 8) and thus affects the start of the SCI transmission and the next data transmission. In addition, for data transmissions scheduled in Mode 2, different Mode2data_offset values can be used in different sidelink grant processes, thereby allowing even the same T-RPT bitmap for data transmissions of different D2D transmissions. , it is possible to ensure that the data transmissions do not overlap in time.

FIG. 13 is a sequence diagram of UE operations for performing D2D transmission according to the first embodiment. The concept illustrated in FIG. 13 applies essentially equally to D2D transmissions scheduled in Mode 1 and D2D transmissions scheduled in Mode 2, but the specifically illustrated order of steps is such that the UE Applies to mode 1 (eNB-scheduled scenario) receiving sidelink grants from Furthermore, for D2D transmissions scheduled in Mode 2, the UE first selects the sidelink destination group(s) to which the data is to be transmitted, after which the UE selects the appropriate (one or more ) obtain the corresponding (various) sidelink grants by autonomously selecting from the transmit radio resource pool. Based on the sidelink grant thus obtained, sidelink control information and corresponding sidelink data are generated to perform D2D transmission.

As evident from FIG. 13, in this exemplary scenario, it is assumed that there are N sidelink grant processes available in the UE to handle the corresponding sidelink grants. N is greater than or equal to 1 (N≧1), but less than or equal to the maximum number of sidelink grant processes (N≦maximum number). In FIG. 13, N is not the maximum number of sidelink grant processes that can be configured for the UE, but the number of sidelink grant processes currently “active” to handle each previously acquired sidelink grant. is a number. That is, the UE has obtained one sidelink grant for each of the N sidelink grant processes.

FIG. 13 shows that the D2D transmissions in each sidelink grant process are independent of each other, but essentially concurrent so that these D2D transmissions are performed within the same SC period.

On the other hand, FIG. 14 shows the D2D communication timing for the scenario scheduled in mode 1 during one SC period according to the first embodiment. Figure 14 is based on the illustration already used in Figure 8 and also shows the SA-offset time after which the SC period begins and which is shown in the sidelink grant received from the eNodeB. Scheduling assignments (sidelink control information) are transmitted using the corresponding transmission pool resources allocated. Again in this exemplary scenario, it is illustratively assumed that the first transmission of SCI is followed by three retransmissions of the same SCI message. The UE then starts D2D data transmission in the next uplink subframe after sending the scheduling assignment. A MAC PDU is transmitted in its first transmission and retransmission(s) set by the T-RPT (Transmission Time Resource Pattern).

As is clear from FIG. 14, the UE has two sidelink grant processes (in this exemplary case sidelink grant process with ID 1 and sidelink grant process with ID 2) that are each addressed to a different sidelink grant process. link grant process) is assumed to be received from the eNodeB. As described in connection with FIG. 13, the UE may send D2D transmissions in each sidelink grant process (i.e. in each of the two sidelink grants in this case) to essentially the same sidelink control period (e.g. SA_offset). later, and continue for the length of the sidelink control period). Figure 14 depicts this situation, showing two D2D transmissions of scheduling assignments and corresponding data performed by the transmitting user equipment. The exemplary scenario assumed in FIG. 14 assumes that the top D2D transmission is destined for a different sidelink destination group than the bottom D2D transmission (although two D2D transmissions can also carry data for the same sidelink destination group).

As mentioned above, the radio resources used to transmit several D2D transmissions do not overlap in time. As is evident from Figure 14, the eNodeB selected non-overlapping radio resources in the time domain for transmitting the two scheduling assignments and indicated them in the sidelink grant. In addition, the eNodeB selected non-overlapping radio resources in the time domain for transmitting data and corresponding control information (SCI) for each of the two D2D transmissions and indicated them in the sidelink grant. As can be seen from FIG. 14, the respective T-RPT bitmaps are different between the two D2D transmissions.

FIG. 15 shows the D2D communication timing for the scenario scheduled in mode 2 during one SC period according to the first embodiment. FIG. 15 is based on the illustration already used in FIG. 7 of the background art section. Different from the scenario of Fig. 14, it is assumed that no sidelink grant is received from the radio base station and two sidelink grants are autonomously selected by the UE. Similar to the illustration in FIG. 14, radio resources for transmitting sidelink control information and data for two D2D transmissions do not overlap in time. In this case, the UE selects non-overlapping corresponding resources in the time domain from the SA_mode2_Tx_pool for transmitting the sidelink control information, and also selects appropriately different T-s for transmitting data in the two D2D transmissions. Select transmission resources for the RPT bitmap and corresponding control information (SCI).

Figures 14 and 15 show scenarios where all available sidelink grants are either scheduled by the eNodeB or selected autonomously. However, the UE may also have valid sidelink grant(s) according to mode 1 and valid sidelink grant(s) according to mode 2 at the same time.

In the above-described implementation of the first embodiment, it is assumed that the UE determines the sidelink destination group for which D2D transmissions are performed within the same SC period, and no further details are given. According to a particular implementation of the first embodiment, the step of determining the sidelink destination group is performed by using (one or more times) a Logical Channel Prioritization (LCP) procedure.

According to one alternative, one LCP procedure is performed for each sidelink grant process (or valid sidelink grant), so that the UE identifies the sidelink destination groups in each sidelink grant process separately from each other. select. As explained in the background art section, according to current standards, the order of processing the sidelink logical channels is not specified and is left to the UE implementation, i.e. destination group selection and selection The order of processing sidelink logical channels belonging to a given destination group is not specified and no prioritization mechanism is implemented. However, this implementation assumes that each sidelink destination group has a corresponding priority associated with it. According to this implementation, the UE performs the LCP procedure separately for each sidelink grant process. More specifically, the UE performs the LCP procedures sequentially, i.e., for example, starting with the LCP procedure for the first sidelink grant process, then performing the LCP procedure for the second sidelink grant process, and so on. It is the same. The UE selects the sidelink destination group that has available data and has the highest corresponding priority in each LCP procedure. Therefore, if the UE has two different destination groups of data available for transmission, after performing the first LCP procedure (according to the first sidelink grant), the higher priority sidelink destination If the group's data still exists in its buffer, the UE selects the same sidelink destination group again in the second LCP procedure.

According to a further alternative, a common LCP procedure is performed by the UE for all sidelink grant processes (or valid sidelink grants), so that the UE assigns sidelink destination groups in all sidelink grant processes. , to choose in an interdependent manner. This implementation also assumes that each destination group has a corresponding priority associated with it. According to this implementation, destination group selection is performed in descending order of destination group priority. Specifically, assuming again that the UE has two different destination groups of data available for transmission, the destination group with the higher priority among the destination groups will receive the first side. Use link grants. However, the second sidelink grant has the lower priority of the destination group even if there remains data available to be sent to the destination group with the higher priority of the destination group. Used for destination groups. If there are additional destination groups, then additional sidelink grants are used as well.

<Second embodiment>
Below, a second embodiment for solving the above-described problem will be described in detail. The main concept of the second embodiment differs from that of the first embodiment. However, the scenario(s) for explaining the principles underlying the second embodiment can be envisioned as well. In particular, we assume a ProSe capable UE, which is therefore capable of performing D2D transmission(s) directly with another UE(s) without going through the eNodeB. . Furthermore, it is assumed that the UE has data available for transmission destined for multiple sidelink destination groups, except that the improved D2D transmission according to the second embodiment is directed to one sidelink at the UE. It applies equally if only destination group data is available for transmission.

According to a second embodiment, D2D transmission is improved by enhancing the sidelink control information to identify multiple sidelink destination groups instead of just one sidelink destination group. Thus, a D2D transmission performed by a UE can carry data for multiple sidelink destination groups identified by corresponding sidelink control information. Radio resources for performing D2D transmissions (of sidelink control information and corresponding data) are defined by sidelink grants available to the UE. Unlike the first embodiment, the UE has only one valid sidelink grant per SC period, similar to the scheme currently defined in 3GPP standards. Therefore, according to the second embodiment, no change is required in this respect.

Further, the UE (which has data available for multiple sidelink destination groups) selects (at least two) specific sidelink destination groups among the sidelink destination groups, and then selects multiple sidelink destination groups. and generate corresponding data packets for D2D transmissions, where the data packets carry data for the number of determined sidelink destination groups. The UE can transmit data for different sidelink destination groups in one D2D transmission within one SC period, and the different sidelink destination groups are transmitted at the beginning of the D2D transmission. Identified by sidelink control information.

FIG. 16 shows a sequence diagram of the behavior of a UE when performing D2D transmission according to the second embodiment, the steps described above, i.e. obtaining a sidelink grant and multiple sidelink destination groups. generating sidelink control information identifying a plurality of sidelink destination groups; generating a data packet carrying data destined for the selected plurality of sidelink destination groups; and finally performing a D2D transmission of the generated sidelink control information and corresponding data destined for a plurality of sidelink destination groups. Although FIG. 16 shows a specific order of steps for purposes of illustration, the second embodiment is not limited to this specific order, and other suitable orders are possible as well. For example, the step of determining various sidelink destination groups can be performed before the step of obtaining the sidelink grant, or the steps of generating sidelink control information and generating data packets can be performed in sequence. can be reversed.

On the other hand, FIG. 17 shows the D2D communication timing for the scenario scheduled in mode 1 during one SC period according to the second embodiment. The exemplary illustration in FIG. 17 is based on the illustration according to FIG. 8 already used in the Background section. As can be seen from FIG. 17, the difference is that according to the second embodiment, each MAC PDU (and its retransmissions) can carry data destined for different sidelink destination groups (FIG. 17 In this particular example of , data destined for three different sidelink destination groups are transmitted within the SC period), whereas in the currently standardized system according to FIG. Conveys sidelink destination group data (although the actual data in the various MAC PDUs differs from MAC PDU to MAC PDU). Although not depicted in FIG. 17, assuming the UE has selected only two different sidelink destination groups for D2D transmission, the first MAC PDU (and its retransmissions) will send the first sidelink destination group. A second MAC PDU (and its retransmissions) can carry data destined for a second sidelink destination group, and a third MAC PDU (and its retransmissions) can carry data destined for a second sidelink destination group. transmission) can again carry data destined for the first sidelink destination group.

Further, as is apparent from FIG. 17, the scheduling assignment (sidelink control information) transmitted at the beginning of the sidelink control period (and its retransmissions) identifies three sidelink destination groups.

The same concepts described in the eNB-scheduled D2D transmission scenario of FIG. 17 can be applied to the UE-scheduled D2D transmission (ie, mode 2).

According to a different implementation of the second embodiment, the sidelink control information message identifies multiple sidelink destination groups directly (i.e., by including multiple corresponding IDs), as described in detail below. or indirectly (ie, by including an ID that is associated with multiple sidelink destination groups).

According to a first implementation of the second embodiment, the sidelink control information message sent as part of the D2D transmission includes one sidelink destination group ID per determined sidelink destination group. In other words, the sidelink control information message directly identifies the sidelink destination group by including corresponding identification information of the sidelink destination group. Accordingly, a sidelink control information message may contain more than one sidelink destination group ID.

According to a variation of the first implementation, a new sidelink control information format (hereinafter exemplarily referred to as SCI format 1) can be defined with several fields for the sidelink destination group ID. . The new SCI format 1 is illustratively the already standardized SCI format 0, but in addition can indicate some sidelink destination group ID (called "group destination ID" in the standard). Accordingly, the new SCI format 1 more specifically corresponds to the already standardized SCI format 0 of Non-Patent Document 3 and includes one or more of the following fields.
- frequency hopping flag - resource block allocation and hopping resource allocation - time resource pattern - modulation coding scheme - timing advance indication

For example, instead of providing eight bits for the group destination ID as in the currently standardized SCI format 0, the new SCI format 1 supports two group destination IDs (i.e. two sidelink destination group IDs). ), so we have 16 bits available. Of course, if the Sidelink Control Information message is to be able to carry more Sidelink Destination Group IDs, more bits must be provided at this point (e.g. 3 different 24 bits for sidelink destination group ID, 32 bits for 4 different sidelink destination group IDs).

As an option for this first implementation of the second embodiment, the receiving UE is aware of the sidelink destination group ID referenced by the corresponding transport block in the D2D transmission. In other words, the receiving UE knows which transport block carries data for which sidelink destination group identified in the SCI. This illustratively implies a predetermined unambiguous relationship (i.e., the rule ). For example, the order of the Group Destination ID(s) (i.e. sidelink destination group IDs) within the SCI is the order of the corresponding transport blocks sent in the D2D transmission (i.e. the transport that carries the data for each sidelink destination group). block) order. For example, when the first group destination ID in the SCI points to destination A and the second group destination ID points to destination B, there are two transport blocks sent within the SC period. , the first transport block contains data destined for group A and the second transport block contains data destined for group B. If there are three transport blocks to be sent within the SC period, the third transport block contains eg data again destined for group A, and so on. Essentially, the receiving UE knows the Group Destination ID of the corresponding transport block within the SCI period according to some pre-defined rule. When implementing this option in the currently defined 3GPP environment, the receiving UE may select one or more ) recognize the 8 least significant bits (LSBs) of the destination Layer 2 ID. As a result, the UE is able to filter D2D transmissions (especially MAC PDUs) according to the sidelink destination groups it is interested in, so that the receiving UE actually receives MAC Decode only PDUs. More specifically, if the DST field of the decoded MAC PDU subheader is equal to the 16 MSBs of any of the UE's destination layer 2 ID(s), the PDU is further processed at the UE. .

According to an alternative implementation, the DST field of the MAC PDU subheader contains the 24 MSBs (eg, full 24 bits) of the destination Layer 2 ID. Based on these 24 bits in the MAC subheader, the receiving UE can uniquely identify the destination Layer 2 ID of the data in the transport block and thus perform MAC filtering. In this case, the order of the group destination IDs in the SCI need not correspond to the order of the corresponding transport blocks sent in the D2D transmission. For example, even if the first group destination ID points to destination A and the second group destination ID points to destination B, if there are two transport blocks sent within the SC period: A first transport block may contain data destined for group B, and a second transport block may contain data destined for group A. The receiving UE can uniquely perform filtering based on the 24-bit destination Layer 2 ID in the MAC PDU subheader, i.e. the receiving UE only filters packets of interest based on the destination Layer 2 ID. can be decrypted.

According to a second alternative implementation of the second embodiment, the sidelink control information message sent as part of the D2D transmission contains only one ID, however this ID may be the determined sidelink Associated with a destination group. As a result, instead of directly identifying the sidelink destination groups by including their corresponding identification information, the sidelink destination groups are indirectly identified by the appropriate ID, and this ID is again used on the receiving end for multiple sidelinks. Can be associated with a link destination group.

Specifically, this second alternative implementation introduces a new ID that is sent in place of the sidelink destination group ID and that is associated with multiple sidelink destination groups. In other words, this new ID (hereinafter exemplarily referred to as a Broadcast ID) identifies the various sidelink destination groups in a many-to-one fashion such that one Broadcast ID is associated with at least two different sidelink destination groups. group together according to the mapping of This new mapping function can be performed by a suitable node in the core network (eg ProSe server function). The ProSe server function can therefore perform such a mapping function in order to associate several sidelink destination groups with each broadcast ID. In this case, the corresponding mapping information (ie Broadcast ID and correspondingly associated sidelink destination group) is provided to the UE and optionally also to the eNodeB. Providing this information may be performed using, for example, RRC signaling, or may be broadcast in system information by the various eNodeBs.

In one variation, the new Broadcast ID is the same size as the Sidelink Destination Group ID normally used to identify the Sidelink Destination Group in the Sidelink Control Information, i.e. 8 bits (Background technology section), so the already defined sidelink control information format 0 can be reused without adaptation. Alternatively, the new Broadcast ID can be a different (eg, larger) size than the sidelink destination group IDs normally used, in which case a new Broadcast ID is used to convey the new Broadcast ID. A sidelink control information format is required.

According to a second alternative implementation of the second embodiment, after the UE determines multiple sidelink destination groups to which data is transmitted in D2D transmissions according to a valid sidelink grant, these determined multiple A corresponding broadcast ID associated with the sidelink destination group of . The UE may then include the determined broadcast IDs in the sidelink control information for D2D transmissions instead of the ID(s) of the sidelink destination group.

On the other hand, a UE that receives a D2D transmission with sidelink control information that includes a broadcast ID may select multiple sidelinks from the received broadcast ID, e.g., based on previously received and stored mapping information from the ProSe server function. Find the link destination group.

According to a variation, for the purpose of maintaining backward compatibility, especially if the broadcast ID has the same size as the previously used ID of the sidelink destination group conveyed in the sidelink control information message, the sidelink Appropriate information (such as flags) may be included in the sidelink control information message as to whether the control information message contains a new broadcast ID or a normal sidelink destination group ID. In this case, a new sidelink control information format that further includes this flag may be required. Therefore, the transmitting UE may itself include the Broadcast ID (when data for some sidelink destination groups are sent in a D2D transmission) or the normal sidelink destination group ID (for D2D transmissions). When only one sidelink destination group's data is sent in a sidelink destination group), the corresponding flag is set accordingly. On the other hand, the receiving UE considers the value of this flag when determining which sidelink destination group(s) the received D2D is actually intended for.

Thus far, two alternative implementations of the second embodiment have been described, each of which allows sidelink control information to identify multiple sidelink destination groups when needed.

Therefore, a UE with data available for transmission of several sidelink destination groups determines which sidelink destination group among these multiple sidelink destination groups it will transmit data to in the next D2D transmission. . Then, to identify the determined multiple sidelink destination groups, either by including several IDs according to the first alternative implementation described above, or one suitable broadcast ID according to the second alternative implementation described above. to generate the corresponding sidelink control information message.

Additionally, the UE generates corresponding data packets (ie, MAC PDUs) destined for multiple sidelink destination groups for transmission as part of the D2D transmission within the SC period. For example, the first transport block (MAC PDU) generated by the UE in the SC period may carry data destined for the first sidelink destination group, and the 2 The second transport block can carry data destined for the second sidelink destination group, and so on. This can be easily understood from the illustration of FIG.

However, the number of sidelink destination groups to which data can be sent by D2D transmission within one SC period also depends on the length of the SC period and/or the T-RPT pattern given by the sidelink grant. Please note that For example, in the exemplary scenario of FIG. 17, the length of the sidelink control period in combination with the T-RPT bitmap selected allows three separate MAC PDUs to be transmitted within one SC period. Therefore, data destined for up to three sidelink destination groups can be sent by the UE. Setting different lengths of SC periods or choosing different T-RPT patterns (e.g. fewer retransmissions) allows more or fewer sidelink destination groups to be transmitted within one SC period. can be determined.

In the above example, the UE determines (three) different destination groups to which data is sent via D2D transmission, but the same destination group(s) may each be selected by the UE.

Further details of the various steps performed by the UE to successfully perform a D2D transmission are omitted here, but refer to the corresponding sections in the Background section.

A corresponding operation at the receiving end may receive a D2D transmission containing data destined for some sidelink destination group. The receiving UE identifies some sidelink destination groups from the sidelink control information message (Group Destination ID) and thus whether it is interested in that D2D transmission (i.e. the UE can identify SCI are interested in receiving data to one or more of the sidelink destination groups identified by the identifiers in the . If the UE is interested, the corresponding data in the D2D transmission is received and decoded in an appropriate manner by the receiving UE. In this case, the receiving UE determining the sidelink destination group for each MAC PDU of the D2D transmission to determine if the receiving UE wishes to receive and decode the data in the MAC PDU. can be done.

According to currently standardized procedures for transmitting MAC PDUs in sidelink D2D transmissions, e.g. A header contains information about the sidelink destination group of the contained data. Specifically, in the "DST" field of the MAC header, the 16 most significant bits of the destination Layer 2 ID are transmitted, and the receiving UE can identify the sidelink destination group by these bits. The currently standardized SCI message contains the 8 least significant bits of the destination Layer 2 ID, and these 8 LSBs in combination with the 16 MSBs in the MAC header allow the receiving UE to sidelink A destination group (ie, destination layer 2 ID) can be uniquely identified. Therefore, the receiving UE can filter the D2D transmissions (especially MAC PDUs) according to the sidelink destination group it is interested in, and thus the receiving UE is actually interested in the sidelink destination group. Decode only MAC PDUs that contain data. More specifically, if the DST field of the decoded MAC PDU subheader is equal to the 16 MSBs of any of the UE's destination layer 2 ID(s), the PDU is further processed at the UE. .

According to one implementation, the DST field of the MAC PDU subheader is the 24 MSBs (e.g., the full 24 bits) of the destination Layer 2 ID, rather than just the 16 MSBs of the destination Layer 2 ID as currently standardized. including. Based on these 24 bits in the MAC subheader, the receiving UE can uniquely identify the destination Layer 2 ID of the data in the transport block and thus perform MAC filtering. This scheme is particularly advantageous in the second embodiment described above, in which several group destination IDs are mapped to one broadcast ID, because the receiving UE is able to identify the group destination ID (i.e. the corresponding 8 LSBs) of the destination Layer 2 ID of the transport block. Recognition by the receiving UE based on the broadcast ID basically means that the transport block within the SC period contains data destined for one of the group destination IDs mapped to that broadcast ID. The only thing is that it is possible. For example, if Group Destination ID = '0' and Group Destination ID = '1' are mapped to Broadcast ID = '0', the receiving UE will ensure that the first transport block in the SC period is Group Destination ID = '1'. It does not know whether it has '0' or Group Destination ID = '1'. The same applies for other transport blocks within the SC period. According to current standards, the DST field in the MAC PDU subheader only contains the 16 MSBs of the destination Layer 2 ID, so the receiving UE does not know the complete destination Layer 2 ID of the data in the transport block. It cannot be uniquely identified (because the receiving UE does not know the 8 LSBs (Group Destination ID) of the destination Layer 2 ID).

The above description of the second embodiment assumes that the UE has valid sidelink grants, but does not elaborate on how the UE obtains these valid sidelink grants. In the operation of the UE according to the principles of the second embodiment, it is important whether the UE acquires the sidelink grant according to Mode 1 (from the eNB) or according to Mode 2 (R2 autonomously selected by the UE). is not. Therefore, the second embodiment applies to both the sidelink grant obtained in mode 1 and the sidelink grant obtained in mode 2. Specifically, for Mode 1, sidelink grants are sent to the eNodeB, e.g. based on corresponding requests from the UE (e.g. scheduling requests or RACH procedures and corresponding buffer status information as described in the Background section). was received from Details regarding these procedures and the corresponding sidelink scheduling messages sent from the eNodeB to the UE are omitted here, but please refer to the corresponding sections in the Technical Background section. For Mode 2, the sidelink grant is autonomously selected by the UE from the corresponding transmission radio resource pool for transmitting scheduling control information and data. Details regarding these procedures for Mode 2 are also omitted here, but please refer to the corresponding sections in the Background Art section.

In the above implementation of the second embodiment, it was described that the UE determines multiple sidelink destination groups to which D2D transmissions are to be performed within the SC period, but no further details are given. . According to a particular implementation of the second embodiment, the step of determining multiple sidelink destination groups is performed by the UE through the use of (one or more) logical channel prioritization (LCP) procedures. can be done. In particular, the UE can decide in the LCP procedure which sidelink destination group's data should be sent.

According to an alternative to the second embodiment, the UE is allowed to send data to multiple different sidelink destination groups as long as the corresponding group destination IDs (sent in the SCI) are the same. be done. More specifically, according to current standards, the group destination ID transmitted in the SCI on the physical sidelink control channel is the 8 least significant bits (LSBs) of the destination layer 2 ID. As long as the UE multiplexes logical channels in PDUs of a source Layer 2 ID and destination Layer 2 ID pair (where the 8 LSBs of the destination Layer 2 ID are the same), the UE can only use one SC period. data can be sent to multiple different sidelink destination groups within the This implementation requires virtually no changes to currently standardized procedures. Since the group destination ID is the same, the intended receiving UE will not fail to receive the corresponding data transmission on SL-DCH. As an example, the transmitting UE may transmit, within one SC period, data destined for a sidelink destination group having destination layer 2 ID="111111111111111000000000" and destination layer 2 ID="111111111111111100000000". , since the 8 LSBs are the same in both cases (the Group Destination ID sent in the SCI in this case is "00000000").

<Hardware and software implementation of the present disclosure>
Another exemplary embodiment relates to implementing the various embodiments described above using hardware, software, or software cooperating with hardware. In this context, a user terminal (mobile terminal) and an eNodeB (base station) are provided. User terminals and base stations are configured to perform the methods described herein and include corresponding entities (receivers, transmitters, processors, etc.) that are appropriately involved in these methods.

It is further recognized that various embodiments can be implemented or performed using a computing device (processor). A computing device or processor may be, for example, a general purpose processor, digital signal processor (DSP), application specific integrated circuit (ASIC), field programmable gate array (FPGA), or other programmable logic device. Various embodiments may also be performed or embodied by combinations of these devices. In particular, each functional block used in the description of each embodiment described above can be implemented by an LSI as an integrated circuit. These functional blocks can be formed individually as chips, or a single chip can be formed to include some or all of the functional blocks. These chips may include data inputs and outputs coupled to them. LSIs are also called ICs, system LSIs, super LSIs, or ultra LSIs depending on the degree of integration. However, the technology for implementing integrated circuits is not limited to LSI, but can be accomplished using dedicated circuits or general-purpose processors. Furthermore, an FPGA (Field Programmable Gate Array) that can be programmed after the LSI is manufactured, or a reconfigurable processor that can reconfigure connections and settings of circuit cells arranged inside the LSI can be used.

Additionally, various embodiments may also be implemented by software modules. These software modules can be executed by a processor or directly in hardware. Also a combination of software modules and a hardware implementation is possible. The software modules may be stored on any kind of computer readable storage media, for example RAM, EPROM, EEPROM, flash memory, registers, hard disks, CD-ROM, DVD, etc. Furthermore, it should be noted that individual features of a plurality of different embodiments may be the subject of another embodiment, either individually or in any combination.

It will be appreciated by those skilled in the art that various changes and/or modifications may be made to the present disclosure as illustrated in specific embodiments without departing from the concept or scope of the invention as broadly described. will be done. Accordingly, the embodiments set forth herein are to be considered in all respects illustrative and not restrictive of the invention.

Claims (5)

A radio base station for allocating radio resources to a transmitting user equipment for performing direct communication transmissions over a direct sidelink connection to one or more receiving user equipment in a communication system, said transmitting user equipment comprising:
At least two sidelink grant processes are available to the transmitting user equipment such that the transmitting user equipment is capable of receiving at least two sidelink grants covering direct communication transmissions performed within the same transmission control period. each one of the at least two sidelink grant processes is associated with identification information and can be associated with one sidelink grant;
- a processor configured to generate a sidelink grant and associate the generated sidelink grant with one sidelink grant process of the at least two sidelink grant processes;
- the processor is configured to generate a sidelink scheduling message including identification of the one sidelink grant process associated with the sidelink grant;
the processor;
- a transmitter configured to transmit the generated sidelink scheduling message to the transmitting user equipment;
A radio base station equipped with The processor is further configured to generate another sidelink grant and associate the generated another sidelink grant with another sidelink grant process of the at least two sidelink grant processes. and the processor is further configured to generate another sidelink scheduling message including identification information of the another sidelink grant process associated with the another sidelink grant; a machine configured to transmit the generated further sidelink scheduling message to the transmitting user equipment;
Thus, said transmitting user equipment performs a direct communication transmission within the same transmission control period for each sidelink grant process having a correspondingly associated sidelink grant.
The radio base station according to claim 1. the sidelink scheduling message transmitted by the radio base station further comprising information about content of scheduling control information to be transmitted by the transmitting user equipment, and in the direct communication transmission the scheduling control information and indicating the radio resource to be used for transmitting data;
Optionally, the sidelink scheduling message transmitted by the radio base station is a 3GPP DCI format 5 type message, and further the identification information of the sidelink grant process is padded in the DCI format 5 type message. encoded in the portion used for
The radio base station according to claim 1 or 2. A method performed by a radio base station for allocating radio resources to a transmitting user equipment for transmitting direct communication transmissions over a direct sidelink connection to one or more receiving user equipments in a communication system. and
At least two sidelink grant processes are available to the transmitting user equipment such that the transmitting user equipment is capable of receiving at least two sidelink grants covering direct communication transmissions performed within the same transmission control period. wherein each one of said at least two sidelink grant processes is associated with identification information and is capable of being associated with one sidelink grant, said method comprising:
- generating a sidelink grant and associating said generated sidelink grant with one sidelink grant process of said at least two sidelink grant processes;
- generating a sidelink scheduling message including identification of the one sidelink grant process associated with the sidelink grant;
- transmitting the generated sidelink scheduling message to the transmitting user equipment;
A method, including Controlling a radio base station's process of allocating radio resources to a transmitting user equipment for the transmitting user equipment to perform direct communication transmissions over direct sidelink connections to one or more receiving user equipments in a communication system. an integrated circuit,
At least two sidelink grant processes are available to the transmitting user equipment such that the transmitting user equipment is capable of receiving at least two sidelink grants covering direct communication transmissions performed within the same transmission control period. wherein each one of said at least two sidelink grant processes is associated with identification information and is capable of being associated with one sidelink grant, said process comprising:
- generating a sidelink grant and associating the generated sidelink grant with one sidelink grant process of the at least two sidelink grant processes;
- generating a sidelink scheduling message including identification of the one sidelink grant process associated with the sidelink grant;
- sending the generated sidelink scheduling message to the transmitting user equipment;
An integrated circuit, including:

Images