JP6916254B2 - Multiple ProSe group communication during side link control period - Google Patents

Description

The present disclosure relates to a method of allocating radio resources to a transmitting user device for performing direct communication transmission through a direct side link connection to one or more receiving user devices. In addition, the disclosure provides user equipment and base stations involved in the methods described herein.

<Long Term Evolution (LTE)>
Third-generation mobile communication systems (3Gs) based on WCDMA® wireless access technology are being deployed on a wide scale around the world. High Speed Downlink Packet Access (HSDPA) and Enhanced Uplink (also known as High Speed Uplink Packet Access (HSUPA)) were introduced as the first steps in enhancing, developing and evolving this technology. , Extremely competitive wireless access technology is provided.

In order to meet the ever-increasing demand from users and to be competitive with new wireless access technologies, 3GPP has introduced a new mobile communication system called Long Term Evolution (LTE). LTE is designed to provide the carriers required for high-speed data and media transmission and high-capacity voice support over the next decade. The ability to provide high bitrates is an important strategy in LTE.

The work item (WI) specifications for LTE (Long Term Evolution) include E-UTRA (Evolved UMTS Terrestrial Radio Access (UTRA)) and E-UTRAN (Evolved UMTS Terrestrial Radio Access Network (UTRAN)). : Evolved UMTS Radio Access Network), and will eventually be released as Release 8 (LTE Release 8). LTE systems are packet-based efficient radio access and radio access networks that provide all IP-based functionality at low latency and low cost. In LTE, multiple scalable transmit bandwidths (eg, 1.4 MHz, 3.0 MHz, 5.0 MHz, 10.0 MHz, 15.0 MHz, etc., are used to achieve flexible system deployments using a given spectrum. And 20.0 MHz) is specified. Radio access based on OFDM (Orthogonal Frequency Division Multiplexing) is adopted for the downlink. This is because such radio access is inherently less susceptible to multipath interference (MPI) due to its low symbol rate, uses cyclic prefixes (CP), and supports a variety of transmit bandwidth configurations. Because it is possible. For the uplink, wireless access based on SC-FDMA (Single-Carrier Frequency Division Multiple Access) is adopted. This is because, considering that the transmission output of the user equipment (UE) is limited, it is prioritized to provide a wide coverage area rather than improving the peak data rate. In LTE Release 8/9, a number of major packet radio access technologies (eg MIMO (Multiple Input Multioutput) Channel Transmission Technology) have been adopted to achieve a highly efficient control signaling structure.

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

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

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

<Component carrier structure in LTE>
The downlink component carriers of the 3GPP LTE system are further divided in the time-frequency domain in the so-called subframe. In 3GPP LTE, each subframe is divided into two downlink slots as shown in FIG. 2, where the first downlink slot provides a control channel area (PDCCH area) within the first OFDM symbol. Be prepared. Each subframe consists of a given number of OFDM symbols in the time domain (12 or 14 OFDM symbols in 3GPP LTE (Release 8)), and each OFDM symbol extends over the bandwidth of the component carrier. Therefore, each OFDM symbol is composed of several modulation symbols transmitted by its respective subcarriers. In LTE, the transmitted signal in each slot is described by a resource grid of ^{N DL} _RB x N ^RB _sc lines 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 transmit bandwidth set in the cell ^{and satisfies N min, DL} _RB ≤ N ^DL _RB ≤ N ^{max, DL} _{RB, in} which case N ^{min, DL} _RB = 6 and N ^{max and DL} _RB = 110 are the minimum and maximum downlink bandwidths supported by the specifications of the current version, respectively. ^NRB _sc is the number of subcarriers in one resource block. For sub-frame structure of conventional cyclic ^prefix, which is _{^{N RB sc = 12, N DL}} symb = 7.

Assuming a multi-carrier communication system that uses, for example, OFDM, such as that used in 3GPP Long Term Evolution (LTE), the smallest unit of resources that can be allocated by the scheduler is one "resource block". As illustrated in FIG. 2, the physical resource block (PRB) is a continuous OFDM symbol (for example, 7 OFDM symbols) in the time domain and a continuous subcarrier (for example, 12 subcarriers of component carriers) in the frequency domain. Is defined as. Therefore, in 3GPP LTE (Release 8), the physical resource block is composed of resource elements and corresponds to one slot in the time domain and 180 kHz in the frequency domain (more details on the downlink resource grid can be found in, for example, Non-Patent Document 1-6. 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 the subframe when the so-called "normal" CP (cyclic prefix) is used, and the so-called "extended" CP There are 12 OFDM symbols in the subframe when used. For technical purposes, the same continuous subcarrier-equivalent time-frequency resource that spans the entire subframe is referred to below as a "resource block pair" or a synonymous "RB pair" or "PRB pair".

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

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

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

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

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

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

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

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

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

The distance between the center frequencies of the 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 the orthogonality of the subcarriers at 15 kHz intervals. Depending on the aggregation scenario, n × 300 kHz spacing can be facilitated by inserting a small number of unused subcarriers between successive component carriers.

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

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

The features of the downlink PCell and the uplink PCell are as follows.
• For each SCell, the use of uplink resources by user equipment in addition to downlink resources can be configured (thus, the number of DL SCCs configured is always greater than or equal to the number of UL SCCs and uplinks. SCell cannot be configured to use resources only).
-Downlink PCells, unlike SCells, cannot be deactivated.
-Reestablishment is triggered when Rayleigh fading (RLF) occurs in the downlink PCell, but reestablishment is not triggered when RLF occurs in the downlink SCell.
-Non-access layer information is acquired from the downlink PCell.
The PCell can only be modified by a handover procedure (ie, security key change and RACH procedure).
-PCell is used for transmission of PUCCH.
-The uplink PCell is used for transmitting the uplink control information of the first layer.
• From a UE perspective, each uplink resource belongs to only one serving cell.

Component carriers can be configured and reconfigured, as well as added and removed by the RRC. Activation and deactivation are done via MAC control elements. During in-LTE handover, the RRC can also add, remove, or reconfigure SCells for use in target cells. When adding a new SCell, dedicated RRC signaling is used to send the SCell system information (necessary for transmission / reception) (similar to the handover in LTE Release 8/9). When SCells are added to one UE, a serving cell index is set for each SCell. The PCell always has a serving cell index of 0.

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

When carrier aggregation is set, user equipment can be scheduled for multiple component carriers at the same time, but only one random access procedure can proceed at the same time. In cross-carrier scheduling, the PDCCH of a component carrier allows the resources of another component carrier to be scheduled. For this purpose, a component carrier identification field (referred to as "CIF") has been introduced into each DCI (Downlink Control Information) format.

When cross-carrier scheduling is not taking place, the link between the uplink component carrier and the downlink component carrier (established by RRC signaling) can identify the uplink component carrier to which the grant applies. The link of the downlink component carrier to the uplink component carrier does not necessarily have to be one-to-one. In other words, two or more downlink component carriers can be linked to the same uplink component carrier. On the other hand, one downlink component carrier can be linked to only one uplink component carrier.

<Uplink access method in LTE>
Uplink transmission requires power-efficient transmission by the user terminal in order to maximize coverage. As the uplink transmission method of E-UTRA, a method that combines single carrier transmission and FDMA with dynamic bandwidth allocation is selected. The main reason for choosing single-carrier transmission is that it has a lower peak-to-average power ratio (PAPR) compared to multicarrier signals (OFDMA), which in turn improves power amplifier efficiency and coverage. This is because (the data rate is high with respect to the given terminal peak power). At each time interval, NodeB allocates the user a unique time / frequency resource for transmitting user data, which ensures orthogonality within the cell. Orthogonal multiple access on the uplink increases spectral efficiency by eliminating in-cell interference. Interference caused by multipath propagation is dealt with in the base station (NodeB) by inserting a cyclic prefix in the transmission signal.

_{The basic physical resources used to transmit data consist of frequency resources of size BW grant} over a time interval (eg 0.5 ms subframe) (encoded information bits are this resource). Mapped to). The subframe (also referred to as transmission time interval (TTI)) is the minimum time interval for transmitting user data. However, by concatenating the subframes, it is also possible to allocate the _{frequency resource BW grant to the user for a time longer than 1 TTI.}

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

For scheduled controlled access, the eNB allocates specific frequency resources (ie, time / frequency resources) over a specific time to the UE to transmit uplink data. Some time / frequency resources can be allocated for contention-based access, and the UE can transmit within this time / frequency resource without being initially scheduled by the eNB. One scenario in which a user device makes contention-based access is, for example, random access, that is, when the UE makes the first access to a cell, or when it makes the first access to request an uplink resource. Is.

For scheduled controlled access, the NodeB scheduler allocates a unique time-frequency resource for uplink data transmission to the user. More specifically, the scheduler determines:
-UE (s) that allow transmission
-Physical channel resources-Transport format (modulation / coding method (MCS)) that mobile terminals should use for transmission

The allocation information is signaled to the UE via a scheduling grant sent on the layer 1 / layer 2 control channel. In the following, for the sake of brevity, this channel will be referred to as an uplink grant channel. Therefore, the scheduling grant message contains, as information, the portion of the frequency band that the UE is allowed to use, the validity period of the grant, and the transport format that the UE must use for future uplink transmissions. .. The shortest validity period is one subframe. Grant messages can also include additional information depending on the method selected. Only grants "for each UE" are used as grants granting the right to transmit on the uplink shared channel (UL-SCH) (ie, there is no "per radio bearer" grant in each UE). Therefore, the UE needs to allocate the allocated resources among the radio bearers according to some rules. Unlike the case of HSUPA, the transport format is not selected on the user device side. The eNB determines the transport format based on some information (eg, reported scheduling information and QoS information), and the user equipment must follow the selected transport format. In HSUPA, NodeB allocates the maximum uplink resources and the UE selects the actual transport format for data transmission accordingly.

Since wireless resource scheduling is the most important function in a shared channel access network in determining quality of service, the uplink scheduling method in LTE is satisfied for the purpose of enabling efficient quality of service (QoS) management. There are some requirements that should be met.
• You should avoid running out of resources for low-priority services.
Quality of service (QoS) should be clearly distinguished for each wireless bearer / service.
-Perform a detailed buffer report (for example, a report for each wireless bearer or a report for each wireless bearer group) in the uplink report so that the eNB scheduler can identify which radio bearer / service data is transmitted. Should be able to.
• Quality of service (QoS) should be clearly distinguishable between services of different users.
-It should be possible to provide a minimum bit rate for each wireless bearer.

As can be seen from the set of conditions listed above, one important aspect of LTE scheduling schemes is that operators distribute their total cell capacity among individual radio bearers of different QoS classes. Is to provide a mechanism that can control. The wireless 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 particular amount of its total cell capacity to the total traffic associated with a particular QoS class radio bearer. The main purpose of adopting this class-based method is to be able to distinguish the processing of packets according to the QoS class to which the packet belongs.

<Layer 1 / Layer 2 control signaling>
Layer 1 / Layer 2 control signaling is used to inform the scheduled user of the user's allocation status, transport format, and other transmission-related information (eg, HARQ information, transmit power control (TPC) commands). It is sent downlink with the data. The first-layer / second-layer control signaling is multiplexed with the downlink data in the subframe (assuming that the user allocation can change in subframe units). 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 the subframe. The TTI length can be constant for all users within the service area, different for different users, or even dynamic for each user. Layer 1 / layer 2 control signaling generally only needs to be transmitted once per TTI. In the following, it is assumed that TTI is equal to one subframe without loss of generality.

Layer 1 / Layer 2 control signaling is transmitted over the physical downlink control channel (PDCCH). The PDCCH conveys the message as downlink control information (DCI), which in most cases contains resource allocation and other control information intended for groups of mobile terminals or UEs. In general, several PDCCHs can be transmitted within one subframe.

It should be noted that in 3GPP LTE, the allocation for uplink data transmission (also referred to as uplink scheduling grant or uplink resource allocation) is also transmitted by PDCCH. In addition, 3GPP Release 11 introduces EPDCCH, which performs essentially the same function as PDCCH (ie, conveys layer 1 / layer 2 control signaling), but the details of the transmission method are different from PDCCH. Further details are described in particular in the current versions of Non-Patent Document 1 and Non-Patent Document 2 (incorporated herein by reference). Therefore, most of the items outlined in the background art and embodiments apply to PDCCH and EPDCCH, or other means of transmitting layer 1 / layer control signaling, unless otherwise specified.

Information sent by layer 1 / layer control signaling for the purpose of allocating uplink or downlink radio resources (especially LTE (-A) Release 10) can generally be categorized into the following items: can.
-User identification information: Indicates the user to be assigned. This information is generally included in the checksum by masking the CRC with user identification information.
-Resource allocation information: Indicates the resource allocated to the user (eg resource block (RB)). Alternatively, this information is referred to as resource block allocation (RBA). The number of resource blocks (RBs) assigned to users can be dynamic.
-Carrier indicator: The control channel transmitted by the first carrier is used to allocate resources associated with the second carrier (ie, resources associated with the second carrier or resources associated with the second carrier) (ie). Cross-carrier scheduling).
-Modulation / coding method: Determine the modulation method and coding rate to be adopted.
-HARQ information: New data indicator (NDI), redundant version (RV), etc., which are especially useful when retransmitting a data packet or part of it.
− Power control command: Adjusts the transmission power when transmitting the uplink data or control information to be allocated.
− Reference signal information: The applied cyclic shift or orthogonal cover code index used to send or receive the reference signal to be assigned.
-Uplink Allocation Index or Downlink Allocation Index: Used to identify the order of allocation and is especially useful in TDD systems.
− Hopping information: For example, information on whether to apply resource hopping for the purpose of increasing frequency diversity and how to apply it.
-CSI request: Used to trigger the allocated resource to send channel state information.
-Multi-cluster information: Used to indicate and control whether to send in a single cluster (a contiguous set of resource blocks) or a multi-cluster (a contiguous set of at least two contiguous resource blocks). It is a flag. Multi-cluster allocation was introduced with 3GPP LTE- (A) Release 10.

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

Downlink control information takes the form of several formats, which differ in overall size from the information contained in the fields described above. The different DCI formats currently defined in LTE are: Section 5.3.3.1 of Non-Patent Document 3 (current version 12.4.0 is available on the 3GPP website. , Incorporated herein by reference). In addition, further details regarding the DCI format and the specific information transmitted in DCI can be found in the technical standards listed above, or in Section 9.3 of Non-Patent Document 4 (incorporated herein by reference). Please refer to.
-Format 0: DCI format 0 is used to transmit resource grants for PUSCH using single antenna port transmission in uplink transmit mode 1 or 2.
-Format 1: DCI format 1 is used to transmit resource allocations for transmission of single codeword PDSCH (downlink transmission modes 1, 2, 7).
-Format 1A: DCI format 1A has the purpose of compactly signaling resource allocation for single codeword PDSCH transmission and the purpose of assigning a dedicated preamble signature to mobile terminals for conflict-free random access. Used for (all send 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 information transmitted is the same as in format 1A, but in addition an indicator of the precoding vector applied to the transmission of the PDSCH is transmitted.
-Format 1C: DCI Format 1C is used to transmit PDSCH allocations in a very compact manner. When format 1C is used, PDSCH transmission is constrained to the use of QPSK modulation. This format is used, for example, to signal paging messages and to broadcast system information messages.
-Format 1D: DCI format 1D is used to compactly signal resource allocation for PDSCH transmission using multi-user MIMO. The information transmitted is the same as for format 1B, but instead of one of the indicator bits of the precoding vector, one bit is used to indicate whether a power offset is applied to the data symbol. exist. This configuration is necessary to indicate whether transmission power is shared between the two user devices. In future versions of LTE, this configuration can be extended to share power among a larger number of user devices.
-Format 2: DCI format 2 is used to transmit resource allocation for PDSCH in the case of closed-loop MIMO operation (transmission mode 4).
-Format 2A: DCI format 2A is used to send resource allocations for PDSCH in the case of open-loop MIMO operation. The information to be transmitted is the same as in the case of format 2, except that when the eNodeB has two transmitting antenna ports, there is no precoding information, and in the case of four antenna ports, it indicates 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 the case of dual layer beamforming (transmission mode 8).
-Format 2C: Introduced in Release 10, used to transmit resource allocation for PDSCH in the 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 in CoMP (cooperative multipoint) (transmission mode 10).
-Formats 3 and 3A: DCI formats 3 and 3A are used to send power control commands for PUCCH and PUSCH, each with a 2-bit or 1-bit power adjustment. These DCI formats include 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 PSCH (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 is the padding bits added to format 0. Add 0 to format 5 until it is equal to the including payload size of format 0.

Sidelink control information is defined in Section 5.4.3 (incorporated herein by reference) of Non-Patent Document 3 (current version 12.4.0), which is a 3GPP technical standard. (Details on side links will be described later).

SCI (Side Link Control Information) can convey side link scheduling information for one destination ID. SCI format 0 is defined for use in PSSCH scheduling. The following information is transmitted in 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 instruction: 11 bits ・ Group destination ID: 8 bits

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

When building a MAC PDU with data from multiple logical channels, the easiest and most intuitive way is to use absolute priority-based methods, which take the space of the MAC PDU into the logical channel priority. Assign to logical channels in descending order. That is, the data from the highest priority logical channel is processed first in the MAC PDU, then the data from the next highest priority logical channel is processed and continued until all the space in the MAC PDU is occupied. .. The absolute priority-based method is quite simple in terms of UE implementation, but can lead to a lack of data resources from lower priority logical channels in some cases. Insufficient resources mean that data from the high priority logical channel cannot send data from the low priority logical channel because it occupies all the space in the MAC PDU.

In LTE, data is transmitted in order of importance, but a preferred bit rate (PBR) is defined for each logical channel in order to avoid resource shortage of data with lower priority. PBR is the minimum data rate guaranteed for a logical channel. At least a small amount of MAC PDU space is allocated to guarantee PBR, even if the logical channels have low priority. Therefore, the problem of resource shortage can be avoided by using PBR.

The step of building a MAC PDU using PBR consists of two substeps. In the first substep, each logical channel is processed in descending order of priority of the logical channel, but the amount of data from each logical channel included in the MAC PDU is initially set to the PBR value set for that logical channel. Limit to the 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 processed again in descending order of priority. The main difference between the second substep compared to the first substep is that in all the higher priority logical channels, only if there is no more data to send, will there be MAC PDU space on each lower priority logical channel. Can be assigned.

The MAC PDU can include not only the MAC SDU from each configured logical channel but also the MAC CE. With the exception of padding BSR, MAC CE has a higher priority than MAC SDU from the logical channel, because MAC CE controls the operation of the MAC layer. Therefore, when building a MAC PDU, the MAC CE (if any) is included first and the remaining space is used for the MAC SDU from the logical channel. Then, if additional space remains 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 Section 5.4.3.1 (incorporated herein by reference) of Non-Patent Document 5 (current version 12.5.0).

The RRC controls the scheduling of uplink data by signaling the following for each logical channel:
-Priority (the higher the priority value, the lower the priority level)
-Prioritized BitRate (set the priority bit rate (PBR))
-BucketSizeDuration (set the bucket size period (BSD))

The UE maintains a _{variable B j} for each logical channel j. B _j is initialized to 0 when the associated logical channel is established, and is incremented by the product PBR × TTI time length for each TTI (PBR is the preferred bit rate of the logical channel j). However, the value of B _j can not exceed the bucket size, the value of B _j is larger than the bucket size of logical channel j, the value of B _j is set to the bucket size. The bucket size of the logical channel is equal to PBR (priority bit rate) x BSD (bucket size period), and PBR and BSD are set by the upper layer.

<LTE device-to-device (D2D) neighborhood service (ProSe)>
Neighborhood-based applications and services are a new trend in social technology. Areas identified include commercial services and services related to public safety that are of interest to businesses and users. By introducing the Prose feature into LTE, the 3GPP industry will be able to serve this growing market while at the same time urgently in some public safety communities using LTE in tandem. Can meet various needs.

Device-to-device (D2D) communication is a technical element in LTE Release 12. Device-to-device (D2D) communication technology can increase spectral efficiency in D2D as an underlay for cellular networks. For example, if the cellular network is LTE, all physical channels carrying data use SC-FDMA in D2D signaling. In D2D communication, user devices transmit data signals to each other through direct links that use cellular resources, without going through a radio base station. 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.

In ProSe Direct Discovery, a ProSe-enabled user device sends an E-UTRA direct radio signal to another nearby ProSe-enabled user device via a PC5 interface. It is defined as the procedure used to use and discover. FIG. 3 schematically shows a PC5 interface for direct discovery between devices. FIG. 4 schematically shows a radio protocol stack (AS) for ProSe direct discovery.

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

It is assumed that D2D operates in the uplink LTE spectrum (in the case of FDD) or in the uplink subframe of the cell providing coverage (in the case of TDD, except when out of coverage). Moreover, D2D transmission / reception does not use full duplex in a given carrier. From the point of view of the individual user equipment, the given carrier does not use full duplex by D2D signal reception and LTE uplink transmission (ie, D2D signal reception and LTE uplink transmission cannot be performed at the same time).

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

Regarding the user plane protocol, the contents of the agreement related to D2D communication are shown below (Non-Patent Document 6 (current version 12.0.1), section 9.2.2 (incorporated herein by reference). ) Also).

・ PDCP:
− 1: MD2D broadcast communication data (ie, IP packet) should be treated as normal user plane data.
− 1: Header compression / decompression in PDCP can be applied to MD2D broadcast communication data.
-Public safety related D2D broadcast operations use U mode for header compression in PDCP.

・ RLC:
− 1: RLC UM is used for MD2D broadcast communication.
-Segmentation and reconstruction is supported by RLC UM in the second tier.
-The receiving user equipment needs to maintain at least one RLC UM entity per transmitting peer user equipment.
-It is not necessary to configure the receiver's RLC UM entity before receiving the first RLC UM data unit.
-At this time, the need for RLC AM or RLC TM in D2D communication to transmit user plane data is not recognized.

・ MAC:
− 1: HARQ feedback is not assumed in MD2D broadcast communication.
-The receiving user device needs to recognize the source ID for the purpose of identifying the RLC UM entity of the receiver.
-The MAC header contains a second layer (L2) destination ID that enables packet filtering in the MAC layer.
-The second layer (L2) destination ID can be a broadcast address, a group cast address, or a unicast address.
Second layer (L2) group cast / unicast: Before passing the received RLC UM PDU by the second layer (L2) destination ID transmitted in the MAC header, even if it is passed to the RLC entity of the receiver. However, it can be discarded.
Second layer (L2) broadcast: The receiving user equipment processes all RLC PDUs received from all transmitters, reconstructs them, and passes IP packets to the upper layer.
-The MAC subheader contains a logical channel ID (LCID) (to distinguish between multiple logical channels).
-In D2D, at least multiplexing / demultiplexing, priority processing, 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 identification information for use in ProSe direct communication.

-SL-RNTI: Unique identification information used for scheduling ProSe direct communication-Source layer 2 ID: Identify the sender of data in side-link ProSe direct communication. The source layer 2 ID is 24 bits long and is used with the ProSe layer 2 destination ID and LCID (logical channel ID) to identify the RLC UM and PDCP entities in the receiver.
-Destination layer 2 ID: Identify the target person of the data in the side link ProSe direct communication. The destination layer 2 ID has a length of 24 bits and is divided into two bit strings in the MAC layer.
-One bit string is the lowest portion (8 bits) of the destination layer 2 ID and is transferred to the physical layer as the side link control layer 1 ID. It identifies the intended audience for data in side link control and is used to filter packets at the physical layer.
-The second bit string is the uppermost part (16 bits) of the destination layer 2 ID and is transmitted in the MAC header. It is used to filter packets at the MAC layer.

Access layer signaling is not required to form the group and set the source layer 2 ID, destination layer 2 ID, and side link control L1 ID in the UE. These identification information is provided by the upper layer or is derived from the identification information provided by the upper layer. For group cast and broadcast, the ProSe UE ID provided by the upper layer is used directly as the source layer 2 ID, and the ProSe layer 2 group ID provided by the upper layer is used directly as the destination layer 2 ID in the MAC layer. Will be done.

<Radio resource allocation in neighborhood services>
From the viewpoint of the transmitting UE, the UE corresponding to the neighboring service (ProSe compatible UE) can operate in the following two modes of resource allocation.

Mode 1 means a method in which the eNB schedules resource allocation, in which case the UE requests a transmit resource from the eNB (or release 10 relay node) and receives it from the eNodeB (or release 10 relay node). The node) schedules the resources that the UE uses to send "direct" data and "direct" control information (eg, scheduling assignments). The UE needs to be in the RRC_CONNECTED state in order to transmit 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 the usual way (next section "Transmission procedure in D2D communication"). See also). Based on the BSR, the eNB can determine that the UE has data to be transmitted by ProSe direct communication and can estimate the resources required for the transmission.

Mode 2, on the other hand, means a method in which the UE autonomously selects resources, in which case the UE transmits "direct" data and "direct" control information (ie, SA (scheduling allocation)). Select the resources (time and frequency) for yourself from the resource pool (s). One resource pool is defined, for example, by the contents of SIB18 (ie, by the comTxPoolNormalCommon field), and this particular resource pool is broadcast within the cell and is commonly available to all UEs still in the RRC_IDLE state within that cell. Is. In practice, the eNB can define up to four different instances of this pool (ie, four resource pools for sending SA messages and "direct" data). However, the UE always uses the first resource pool defined in the list, even if multiple resource pools are configured on the UE.

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

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

The following rules regarding resource allocation mode apply to the UE.
• If a UE is out of coverage, it can only use mode 2.
• If a UE is in coverage, it can use mode 1 if it has been configured by the eNB to use mode 1.
• If a UE is in coverage, it can use mode 2 if it has been configured by the eNB to use mode 2.
• In the absence of exception conditions, the UE can change from mode 1 to mode 2 or from mode 2 to mode 1 only if the eNB configures the UE to change modes. If the UE is within coverage, the UE will only use the mode indicated by the eNB configuration, unless one of the exceptional cases occurs.
• For example, while T311 or T301 is running, the UE considers itself to be under exceptional conditions.
• When an exceptional case occurs, 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, the user device performs ProSe direct communication transmission on the uplink carrier only on the resources allocated by that cell (even if the carrier's resources are, for example, UICC (general purpose IC card)). : Even if it is preset in the Universal Integrated Circuit Card).

For UEs in the RRC_IDLE state, the eNB can choose one of the following options:
-The eNB provides a mode 2 transmission resource pool in the SIB (system information block). UEs that are allowed ProSe direct communication use these resources for ProSe direct communication in the 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 the RRC_CONNECTED state in order to execute ProSe direct communication transmission.

For UEs in the RRC_CONNECTED state, the following can be done.
-A UE that is in the RRC_CONNECTED state and is permitted to execute ProSe direct communication transmission indicates to the eNB that it wants to execute ProSe direct communication transmission when it is necessary to execute ProSe direct communication transmission.
-The eNB confirms whether the UE in the RRC_CONNECTED state is permitted to transmit ProSe direct communication by using the UE context received from the MME.
-The eNB can set a transmission resource pool of the mode 2 resource allocation method that can be used without restriction for a UE in the RRC_CONNECTED state while the UE is in the RRC_CONCEPTED state by dedicated signaling. Instead, the eNB may use dedicated signaling to set up a mode 2 resource allocation transmission resource pool for a UE in the RRC_CONNECTED state that the UE can use only in exceptional cases. Yes, and unless it is an exceptional case, the UE follows mode 1.

The resource pool for scheduling allocation when the UE is out of coverage can be set as follows.
-The resource pool used for reception is set in advance.
-The resource pool used for transmission is set in advance.

The resource pool for scheduling allocation when the UE is in coverage can be configured as follows:
The resource pool used for reception is set up by the eNB via RRC (in dedicated or broadcast signaling).
The resource pool used for transmission is set by the eNB via RRC when mode 2 resource allocation is used.
-The SCI (side link control information) resource pool (also referred to as the scheduling allocation (SA) resource pool) used for transmission is not recognized by the UE when the mode 1 resource pool is used.
-When mode 1 resource allocation is used, the eNB schedules specific resources for use in transmitting side link control information (scheduling allocation). The specific resource allocated by the eNB is in the resource pool for receiving the SCI provided to the UE.

FIG. 5 shows the use of transmit / receive resources in overlay (LTE) and underlay (D2D) systems.

Whether the UE applies the mode 1 transmission or the mode 2 transmission is basically controlled by the eNodeB. When the UE recognizes a resource capable of transmitting (or receiving) D2D communication, the current state-of-the-art technology uses the corresponding resource only for the corresponding transmission / reception. For example, in FIG. 5, the D2D subframe is used only for the purpose of receiving or transmitting a D2D signal. Since the UE as a D2D device operates in half-duplex mode, it can either receive or transmit a D2D signal at any time. Similarly, the other subframes shown in FIG. 5 can be used for LTE (overlay) transmission and / or reception.

<Transmission procedure in D2D communication>
The procedure for transmitting D2D data differs depending on the resource allocation mode. As mentioned above, in mode 1, the eNB explicitly schedules the resources for communicating the scheduling allocation and D2D data after the corresponding request from the UE. Specifically, the eNB can notify the UE that D2D communication is basically permitted but the mode 2 resource (that is, the resource pool) is not provided. This notification can be made, for example, by exchanging a D2D communication interest notification by the UE with a corresponding response, the D2D communication response, in which case the comTxPoolNormalCommon is added to the corresponding exemplary ProseCommConfig information element described above. A UE that is not included, i.e. wants to initiate direct communication, including transmission, must request E-UTRAN for resource allocation for each individual transmission. Therefore, in such a case, the UE must request the resource for each of the individual transmissions, and the series of steps of the request / allocation procedure in the case of this mode 1 resource allocation is illustrated below.
-Step 1 The UE sends an SR (scheduling request) to the eNB via PUCCH.
Step 2 The eNB grants the uplink resource (for the UE to send a buffer status report (BSR)) via the PDCCH scrambled by C-RNTI.
-Step 3 The UE sends a D2D BSR indicating the state of the buffer via the PUSCH.
Step 4 The eNB allocates D2D resources (for the UE to send data) via the PDCCH scrambled by D2D-RNTI.
Step 5 The D2D transmitting side UE transmits SA / D2D data according to the grant received in step 4.

Scheduling allocation (SA) (also referred to as SCI (side link control information)) provides control information (eg, a pointer to a time-frequency resource for transmitting the corresponding D2D data, a modulation / coding method, a group destination ID). A compact (low payload) message that contains. The SCI conveys sidelink scheduling information for one (ProSE) destination ID. The content of the SA (SCI) basically follows the grant received in step 4 above. The contents of the D2D grant and SA (ie, the contents of the SCI) are, in particular, 5.4 of Non-Patent Document 3 (current version 12.4.0), which defines the SCI format 0 described above in the Background Techniques section. It is defined in Section 3 (incorporated herein by reference).

On the other hand, in the case of resource allocation in mode 2, steps 1 to 4 above are basically unnecessary, and the UE sets resources for transmitting scheduling allocation (SA) and D2D data by eNB. And autonomously select from the provided (one or more) transmit resource pools.

FIG. 6 schematically illustrates scheduling allocation and transmission of D2D data for two UEs (UE-A and UE-B). The resources for sending scheduling quotas are periodic, and the resources used for sending D2D data are indicated by the corresponding scheduling quotas.

FIG. 7 shows the D2D communication timing of mode 2 (autonomous scheduling) during one SA / data period (also known as the SC period (side link control period)). FIG. 8 shows the D2D communication timing of mode 1 (eNB schedules allocation) during one SA / data period. The SC period is a time frame consisting of scheduling allocations and transmission of their corresponding data. As can be seen from FIG. 7, after the SA offset time, the UE uses the transmit pool resource (SA_Mode2_Tx_pool) for scheduling allocation in mode 2 to transmit the scheduling allocation. After the first transmission of SA, the same SA message is retransmitted, eg, three times. The UE then sends D2D data (ie, more specifically the T-RPT bitmap / pattern) after some configured offset (Mode2data_offset) from the first subframe of the SA resource pool (given by SA_offset). ) Is started. A single D2D data transmission of a MAC PDU 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)) is basically a MAC PDU transmission (first transmission) and its retransmission (second, third, and fourth transmission). Define the timing of transmission).

During one SA / data period, the UE can transmit multiple transport blocks (only one per subframe (TTI), i.e. sequentially), but only to one ProSe destination group. In addition, the retransmission of one transport block must be completed before the first transmission of the next transport block is initiated, i.e. only one HARQ process is used to transmit multiple transport blocks. Will be done.

As is clear from FIG. 8, in the resource allocation mode (mode 1) scheduled by the eNB, the D2D data transmission (ie, more specifically the T-RPT pattern / bitmap) is in the SA resource pool. It is started in the next UL subframe after the last iteration of SA transmission. As already described in FIG. 7, the mode 1 T-RPT bitmap (transmission time resource pattern (T-RPT)) is basically a MAC PDU transmission (first transmission) and its retransmission (2). Define the timing of the 3rd, 3rd, and 4th transmissions).

<ProSe network architecture and ProSe entities>
FIG. 9 illustrates a high level of exemplary architecture for non-roaming, including different ProSe applications in UE A and UE B, as well as ProSe application servers and ProSe functions in the network. An example of the architecture of FIG. 9 is taken from Section 4.2 “Architectural Reference Model” of Non-Patent Document 8 (incorporated herein by reference).

Functional entities are presented and described in detail in Section 4.4, “Functional Entities” of Non-Patent Document 8 (incorporated herein by reference). The ProSe function is a logical function used for network-related operations required for ProSe, and plays a different role in each of the features of ProSe. The ProSe function is part of 3GPP's EPC (Evolved Packet Core) and provides all related network services such as authorization, authentication, and data processing related to nearby services. In ProSe direct discovery and direct communication, the UE can obtain unique ProSe UE identification information, other configuration information, and authentication from the ProSe function through the PC3 reference point. Although multiple ProSe functions can be deployed in the network, one ProSe function is shown for ease of explanation. The ProSe function has three main sub-functions that perform different roles depending on the characteristics of the ProSe: the Direct Provision Function (DPF), the Direct Discovery Name Management Function, and the EPC level. It consists of a discovery function (EPC-level Discovery Function). The DPF is used to provide the UE with the necessary parameters for the purpose of using ProSe direct discovery and ProSe direct communication.

As used in this context, the term "UE" means, for example, a ProSe-enabled UE that supports the following ProSe features:
-Exchange ProSe control information between the ProSe-compatible UE and the ProSe function through the PC3 reference point-Procedure for open ProSe direct discovery of another ProSe-compatible UE through the PC5 reference point-One-to-many ProSe through the PC5 reference point Direct communication procedure-Prose UE-Prose procedure for operating as a network repeater. The remote UE communicates with the ProSe UE-network repeater through the PC5 reference point. The ProSe UE-network repeater uses Layer 3 packet forwarding.
-For example, control information is exchanged between ProSe UEs through the PC5 reference point for UE-network repeater detection and ProSe direct discovery.-ProSe control information between another ProSe-compatible UE and the ProSe function through the PC3 reference point. To replace. In the case of a ProSe UE-network repeater, 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, and radio resource parameters). These parameters can be preset in the UE or, if within coverage, can be provided to the ProSe function in the network by signaling through the PC3 reference point.

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

<UE coverage status in D2D>
As already described above, the resource allocation method in D2D communication depends not only on the RRC state (that is, RRC_IDLE and RRC_CONNECTED) but also on the coverage state of the UE (that is, in-coverage and out-of-coverage). If the UE has a serving cell (ie, the UE is in the RRC_CONNECTED state, or the UE is camping on the cell in the RRC_IDLE state), the UE is considered to be in coverage.

The two coverage states described so far (ie, in-coverage (IC) and out-of-coverage (OOC)) are further divided into sub-states in D2D. FIG. 10 shows four types of states to which a D2D UE can be associated, and these states 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 sets whether the UE 1 should use the resource allocation mode 1 or the resource allocation mode 2.
State 2: UE2 has downlink coverage but no uplink coverage (ie, DL coverage only). The network broadcasts (competition-based) resource pools. In this state, the transmitting UE selects the resources used for SA and data from the resource pool set by the network. In such a state, only resource allocation in mode 2 is possible in D2D communication.
State 3: UE3 does not have uplink and downlink coverage, so strictly speaking UE3 is already considered out of coverage (OOC). However, the UE 3 is also within the coverage of some UEs (eg, UE1) that are themselves within the cell coverage, i.e. these UEs can also be referred to as CP relay UEs. Therefore, the area of the UE in the state 3 in FIG. 10 can be referred to as a CP UE relay coverage area. The UE in this state 3 is also referred to as the out-of-coverage (OOC) state 3 UE. In this state, the UE receives some information specific to the cell, which is sent by the eNB (SIB) and out of coverage via the PD2DSCH by the CP UE relay UE within the cell's coverage (SIB). OOC) State 3 Transferred to UE. Network-controlled (competition-based) resource pools are signaled by PD2DSP.
State 4: UE4 is out of coverage and does not receive PD2DSP from another UE within cell coverage. In this state (also referred to as state 4 out of coverage (OOC)), the transmitting UE selects a resource to be used for data transmission from a preset resource pool.

The main reason for distinguishing between state 3 out of coverage (OOC) and state 4 out of coverage (OOC) is to avoid the strong interference that can occur between D2D transmissions from out-of-coverage devices and legacy E-UTRA transmissions. To do. Generally, a D2D capable UE has a D2D SA and a preconfigured resource pool for data transmission for use when out of coverage. When these out-of-coverage UEs use these preset resource pools to send near cell boundaries, interference between their D2D transmissions and legacy transmissions within coverage is communication within the cell. May have an adverse effect on. If the D2D-enabled UEs in coverage transfer the D2D resource pool settings to these out-of-coverage devices near the cell boundaries, the out-of-coverage UEs send their transmissions to those resources specified by eNodeB. It can be limited and thus minimize interference with legacy transmissions within coverage. Therefore, RAN1 has introduced a mechanism by which UEs in coverage transfer resource pool information and other D2D-related settings to devices just outside the coverage area (UEs in state 3).

A physical D2D synchronization channel (PD2DSP) is used to convey this information about the in-cover D2D resource pool to nearby UEs in the network, thus coordinating resource pools within the vicinity of the network.

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

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

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

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

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

For illustration purposes only, consider the following exemplary scenario. Three ProSe logical channels LCH # 1, LCH # 2, and LCH # 3 have been established in the user equipment, and all three are associated with the same ProSe LCG (eg, "11"). Illustratively, it is assumed that LCH # 1 and LCH # 2 are assigned to ProSe destination group 1 and LCH # 3 is assigned to ProSe destination group 2. This scenario is shown in FIG.

<Buffer status report in ProSe>
Buffer status reporting has also been adapted to ProSe and is currently incorporated herein by reference to Section 5.14.1.4 "Buffer Status Reporting" of Non-Patent Document 5 (version 12.5.0). Is defined in).

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

The sidelink buffer state report (BSR) is triggered when some specific event occurs (as detailed in Section 5.14.1.4 of Non-Patent Document 5).

Further, Section 6.1.3.1a (incorporated herein by reference) of Non-Patent Document 5 (Version 12.5.0) describes the ProSe BSR MAC control elements and their corresponding contents. It is defined as follows. The MAC control element of the ProSe buffer status report (BSR) 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 in the index of the destination identification information reported in the destinationInfoList.
LCG ID: The logical channel group ID field identifies the group of logical channels (s) 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 in the ProSe destination group after all TTI MAC PDUs have been built. The amount of data is indicated by the number of bytes.
-R: It is a reserved bit and is set to "0".

FIG. 11 shows the MAC control elements of ProSe BSR in the case of even N (the number of ProSe destination groups) (cited from Section 6.1.3.1a of Non-Patent Document 5).

As described above, the transmission method in inter-device communication is quite different from the normal LTE method, including the use of ProSe destination groups to identify the content of the data. Some of the currently defined mechanisms are quite 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

An exemplary embodiment without limitation of the present invention allocates radio resources for a transmitting user device to perform a direct communication transmission through a direct side link connection to one or more receiving user devices. Provide an improved method. The independent claims provide exemplary embodiments that do not limit the invention. An advantageous embodiment is the subject of the dependent claim.

According to some embodiments, the sender user device (but not limited to), especially in a scenario where data destined for two or more sidelink destination groups is available for transmission in the sender user device. Improves the step of performing direct communication transmission.

A main aspect of the present invention is an integrated circuit that controls a transmitting user device that executes direct communication transmission through a direct side link connection to one or more receiving user devices in a communication system. The process of receiving at least two sidelink grants that handle direct communication transmissions executed within the same transmission control period and at least one of each of the two sidelink grant processes are associated with the identification information.
• Correspondingly associate each of the at least two received sidelink grants with one of each of the at least two sidelink grant processes.
• In each of the at least two sidelink grants, radio resources for performing direct communication transmission of sidelink control information and data through the direct sidelink connection are allocated according to the respective sidelink grants.
It is an integrated circuit including a process of executing a direct communication transmission within the same transmission control period for each side link grant process having the correspondingly associated side link grant.

According to the first aspect, in order to allow the user device to handle several side link grants at essentially the same time, in other words, the user device performs several direct communication transmissions at essentially the same time (eg, the same transmission). Introduce a new concept of sidelink grant process to allow transmission (within control period). Therefore, each direct communication transmission can be configured to transmit the same or different sidelink destination group data.

In the prior art, the sidelink grant is overwritten by the next received sidelink grant. On the other hand, according to this first aspect, it is possible to assign different sidelink grants to different sidelink grant processes by having a plurality of available sidelink grant processes in the UE. That is, the sidelink grant can still be overwritten (if a new sidelink grant from the same sidelink grant process is received), but the UE can have several valid sidelink grants at the same time (need to do an override). do not have). The corresponding ID of each sidelink grant process allows the sidelink grant to be uniquely associated with one of the processes. Furthermore, one sidelink grant process is associated with only one (valid) sidelink grant. When retrieving additional sidelink grants associated with the same sidelink grant process, the previous sidelink grant is overwritten as described above.

Thus, the UE for transmitting direct communication transmissions, including transmission of sidelink control information and data destined for one sidelink destination group, in each of the sidelink grant processes and their associated sidelink grants. Allocate radio resources according to their side link grants.

Therefore, if data from different sidelink destination groups is available for transmission within the user equipment, the user equipment transmits data from different sidelink destination groups using each of the available sidelink grants. You can decide that. Therefore, the transmitting user equipment performs one direct communication transmission per sidelink grant process at essentially the same time (ie, within the same transmission control period), in which case each direct communication transmission has a different sidelink destination group. It can include data as a destination. In one implementation of the first aspect, the radio resources for multiple direct communication transmissions executed within the same transmission control period do not overlap in the time domain. Time division is used in direct communication transmission.

The resource shortage of one side link destination group can be avoided according to the first aspect. Furthermore, there is no change in the transmission method from the point of view of the receiving user equipment, because the transmitting user equipment transmits data of only one sidelink destination group per direct communication transmission (that is, per sidelink grant process). Is. Therefore, the side link control information can remain the same. In one implementation of the first aspect, the step of determining (s) sidelink destination groups to which data should be sent is (s) for all acquired sidelink grants. It can be performed by the sender user equipment using a common logical channel prioritization procedure to determine the sidelink destination group, or the sender user equipment is separate for each sidelink grant. Use the logical channel prioritization procedure.

The principle of the first aspect is that both resource allocation methods (ie, receiving the corresponding side link grant from the radio base station after requested by the transmitting user equipment, and the transmitting user equipment (s). ) How to autonomously select a sidelink grant from the appropriate transmit radio resource pool). When a radio base station transmits a scheduling message including a side link grant to a transmitting user device, the side link scheduling message is (for example, information about the content of scheduling control information to be transmitted by the transmitting user device and scheduling). The sidelink grant process to which the sidelink grant should be associated (besides containing control information and information about the radio resources to be used to transmit the data) can also be identified. Based on this, the transmitting user device can associate the received sidelink grant with the intended sidelink grant process.

According to the second aspect, the direct communication transmission is improved by allowing the scheduling allocation (side link control information) transmitted by the transmitting user device to basically identify a plurality of side link destination groups. .. Therefore, data destined for multiple sidelink destination groups can be used for transmission within the sender user device, and further, sidelinks available for the sender user device to perform direct communication transmission. Assume to have a grant. The transmitting user device determines at least two sidelink destination groups for transmitting data in direct communication transmission among the plurality of sidelink destination groups. The side link control information related to the direct communication transmission transmits the side link control information and the corresponding data to the determined at least two side link destination groups and the determined at least two side link destination groups. Identify the radio resources allocated for. Therefore, the transmitting user device executes direct communication transmission capable of transmitting data of a plurality of side link destination groups.

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

According to an alternative implementation of the second aspect, the sidelink control information message includes one sidelink ID associated with a plurality of sidelink destination groups. In this alternative implementation, a mapping function is introduced to establish a correspondence between different sidelink IDs and the corresponding sidelink destination groups, and the corresponding information about this correspondence is received by the sender user device and the receiver. Must be provided to both side user equipment. After the transmitting user device determines the side link destination group to which data should be transmitted by direct communication transmission, the corresponding side link ID is associated with the determined side link destination group so that the side link ID is associated with the determined side link destination group. Obtained based on. The sidelink ID can then be included in the corresponding sidelink control information instead of the various IDs of the sidelink destination group. On the receiving side, the receiving UE can determine the side link destination group referenced by the side link ID based on this information about the correspondence as well.

The principle of the second aspect is that both resource allocation methods (ie, receiving the corresponding side link grant from the radio base station after the transmitting user equipment requests it, and the transmitting user equipment (s). ) How to autonomously select a sidelink grant from the appropriate transmit radio resource pool).

Thus, in a general first aspect, the technique disclosed herein involves a direct side link connection of one or more transmitting user devices to one or more receiving user devices in a communication system. Provides a method of allocating radio resources for performing direct communication transmissions. The transmitting user equipment is provided with at least two sidelink grant processes so that the transmitting user equipment can handle at least two sidelink grants within the same transmission control period. Each one of at least two sidelink grant processes is associated with the identification information and can be associated with one sidelink grant. At least two sidelink grants are acquired, and each of these sidelink grants is associated with one of at least two sidelink grant processes by the sending user equipment. Further, in each of the at least two side link grants, radio resources for performing direct communication transmission of side link control information and data through the direct side link connection are allocated by the transmitting user device according to the respective side link grants. .. Therefore, the transmitting user device executes direct communication transmission within the same transmission control period for each side link grant process having a correspondingly-associated side link grant.

Thus, in a general first aspect, the technique disclosed herein involves a direct side link connection of one or more transmitting user devices to one or more receiving user devices in a communication system. It provides another way of allocating radio resources to perform direct communication transmissions. In the transmitting user device, data having a plurality of side link destination groups as transmission destinations can be used for transmission. The side link grant used for direct communication transmission is available to the transmitting user device. The transmitting user device determines at least two side link destination groups from a plurality of side link destination groups as destinations for direct communication transmission. The transmitting UE allocates the radio resources used for direct communication transmission according to the available side link grants. The transmitting UE generates a side link control information message that identifies at least two determined side link destination groups and the allocated radio resource. The transmitting UE executes a direct communication transmission of the generated side link control information message and data destined to at least two determined side link destination groups through the direct side link connection.

Thus, in a general first aspect, the techniques disclosed herein perform direct communication transmission through a direct side link connection to one or more receiving user devices in a communication system. To provide user equipment. The transmitting user equipment is provided with at least two sidelink grant processes so that the transmitting user equipment can handle at least two sidelink grants within the same transmission control period. Each one of at least two sidelink grant processes is associated with the identification information and can be associated with one sidelink grant. The processor of the transmitting user equipment acquires at least two sidelink grants and associates each of these acquired at least two sidelink grants with one of at least two sidelink grant processes. In 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 each sidelink grant. Therefore, the transmitting user device executes direct communication transmission within the same transmission control period for each side link grant process having a correspondingly associated side link grant.

Thus, in a general first aspect, the techniques disclosed herein perform direct communication transmission through a direct side link connection to one or more receiving user devices in a communication system. To provide another user device. The transmitting user device includes a buffer that can be used for transmission and stores data that is destined for a plurality of side link destination groups. The side link grant used for direct communication transmission is available to the transmitting user device. The processor of the transmitting user device determines at least two sidelink destination groups from a plurality of sidelink destination groups as destinations for direct communication transmission. The processor allocates the radio resources used for direct communication transmission according to the available sidelink grants. The processor generates a sidelink control information message that identifies at least two determined sidelink destination groups and the allocated radio resource. The processor and transmitter of the transmitting UE perform direct communication transmission of generated sidelink control information messages and data destined to at least two determined sidelink destination groups through a direct sidelink connection.

Thus, in a general first aspect, the techniques disclosed herein are through a direct side link connection of one or more transmitting user devices to one or more receiving user devices in a communication system. Provided is a radio base station, which allocates radio resources for executing direct communication transmission to a transmitting user device. The transmitting user equipment is provided with at least two sidelink grant processes so that the transmitting user equipment can handle at least two sidelink grants within the same transmission control period. Each one of at least two sidelink grant processes is associated with the identification information and can be associated with one sidelink grant. The radio base station processor generates a sidelink grant and associates the generated sidelink grant with at least one of two sidelink grant processes. The processor generates a sidelink scheduling message, which contains the identification information of one sidelink grant process associated with the sidelink grant. The transmitter of the radio base station transmits the generated side link 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 benefits can be provided individually by the various embodiments and features of the content disclosed herein and in the drawings, and all to obtain one or more of these benefits and / or benefits. There is no need to provide.

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

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

An exemplary architecture of a 3GPP LTE system is shown. An exemplary downlink resource grid of subframe downlink slots as defined in 3GPP LTE (Release 8/9) is shown. The PC5 interface for direct discovery between devices is shown schematically. The radio protocol stack for ProSe direct discovery is outlined. Shows the use of transmit / receive resources in overlay (LTE) and underlay (D2D) systems. It shows the scheduling allocation (SA) and the transmission of D2D data for two UEs. It shows the D2D communication timing in mode 2 that the UE autonomously schedules. The D2D communication timing in the scheduling mode 1 scheduled by the eNB is shown. An exemplary model of ProSe architecture in non-roaming scenarios is shown. It shows cell coverage for four different states to which a D2D UE can be associated. Shows the ProSe buffer status reporting MAC control elements defined in the standard. The correspondence between the ProSe logical channel, the ProSe LCG, and the ProSe destination group in an exemplary scenario is shown. A sequence diagram of UE behavior on the transmitting side according to one implementation of the first embodiment is shown. The D2D communication timing in the two D2D transmissions scheduled by the eNB according to one implementation of the first embodiment is shown. The D2D communication timing in two D2D transmissions autonomously scheduled by the UE according to one implementation of the first embodiment is shown. A sequence diagram of UE behavior on the transmitting side according to one implementation of the second embodiment is shown. It shows the D2D communication timing in the eNB-scheduled D2D transmission that conveys the data of some side link destination groups according to one implementation of the second embodiment.

A "mobile station" or "mobile node" or "user terminal" or "user device" is a physical entity within a communication network. A 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 another functional entity on a node or network. A node can have one or more interfaces that attach the node to a communication device or communication medium, and the node can communicate through these interfaces. Similarly, a network entity can have a logical interface that attaches a functional entity to a communication device or communication medium, and the network entity can communicate with another functional entity or communication partner node through the logical interface.

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

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

The claims and the term "sidelink grant process" used in this application should be broadly understood as a process available in a user device to which a sidelink grant can be associated. Illustratively, the sidelink grant process can also be broadly understood as a memory area in a user device in which sidelink grants or sidelink grant information is stored and maintained. Each memory area is managed by the user device (for example, storing and erasing the side link grant information, overwriting the stored side link grant information with the newly received side link grant information).

The scope of claims and the term "transmission control period" used in this application should be broadly understood as the period during which a user device executes scheduling allocation (side link control information) and transmission of corresponding data. In other words, the "transmission control period" can also be understood as the period during which the side link grant is valid. As currently standardized in a 3GPP environment, a "transmission control period" can be understood as an SA / data period, or an SC (side link control) period.

The terms "ProSe destination group" or "sidelink destination group" used in the claims and elsewhere in this application are, for example, the source layer 2 ID and destination layer 2 as defined in 3GPP LTE. It can be understood as one pair of IDs.

The expressions "get (sidelink) grant", "have available (sidelink) grant", "receive (sidelink) grant", and similar expressions are from the radio base station that plays that role. Grants (sidelinks) by acquiring or receiving grants (ie mode 1), or by allowing the UE to autonomously select grant resources from the appropriate (s) transmit resource pool. It should be broadly understood to mean acquiring itself (ie mode 2) (ie the UE internally receives the grant).

Background of the currently standardized transmission methods used for D2D communication (both transmission methods associated with mode 1 (ie, scheduled by eNB) and mode 2 (autonomous scheduling)). Described in the technology section. In particular, at this time, a UE can have only one (valid) side link grant (SL grant) per side link 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 to be a valid grant and has received it before (one or more). ) Overwrite the SL grant. Therefore, since only one SL grant is available per SC period, the UE can only send one scheduling allocation per SC period. On the other hand, at present, the UE can transmit data of only one ProSe destination group per scheduling allocation, that is, scheduling control information (SCI). More specifically, in the PDU (s) associated with one SCI, the UE considers only logical channels that have the same pair of source Layer 2 ID and destination Layer 2 ID. This currently standardized D2D transmission method has some drawbacks.

If the UE has data for more than one ProSe destination group in its buffer, the UE can send data for only one ProSe destination group within one SC period, and thus the remaining (one). Or the data in the ProSe destination group (or more) is basically delayed by at least one additional SC period. This delay can be extremely large, depending on the SC period set and the number of SC periods required to transmit the complete data for one ProSe destination group. This is true even if the resources available for transmission are sufficient to transmit more data than the ProSe destination group that is initially processed. More specifically, the eNB may allocate more D2D transmit resources (by SL grant) than the UE needs, i.e. the UE may allocate one ProSe to utilize all the allocated radio resources. You do not have enough data for the destination group in your buffer. This situation can occur, for example, when the buffer state information received on the eNB side is inaccurate or the information is out of date. In this case, some of the allocated resources remain unused, because these resources cannot be used to send data for another ProSe destination group.

The inventor has conceived the following exemplary embodiments to alleviate the problems described above.

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

The following description should be understood not as limiting the scope of the present disclosure, but merely as an example of embodiments for a deeper understanding of the present disclosure. Those skilled in the art should recognize that the general principles of the disclosure described in the claims can be applied to various scenarios in ways not expressly described herein. be. Therefore, the following scenarios envisioned for the purpose of describing various embodiments do not limit the invention and its embodiments to such scenarios.

<First Embodiment>
Hereinafter, the first embodiment for solving the above problems will be described in detail. The implementation form of the first embodiment will be described with reference to FIGS. 13 to 15.

Some assumptions are made for illustration purposes, but these assumptions do not limit the scope of the embodiments. As an example, a user device (ProSe compatible UE) capable of executing ProSe communication (that is, direct D2D transmission between UEs without going through eNodeB) is assumed. Further, the UE shall have data available for transmission to a plurality of sidelink destination groups (ie, ProSe destination groups), provided that the improved direct communication transmission according to the first embodiment is It also applies when only one sidelink destination group of data is available for transmission in the UE.

The first embodiment improves direct communication transmission by introducing the concept of a sidelink grant process that allows one-to-one assignment of sidelink grants (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. The sidelink grant process can be addressed by the use of the corresponding identifying information (hereinafter exemplifiedly referred to as the sidelink grant process ID), which uniquely identifies the sidelink grant to a particular sidelink grant process. Can be assigned.

In currently standardized systems, the UE can only handle one sidelink grant at the same time (more received (s) sidelink grants overwrite the previous sidelink grant, thus Whereas there is only one valid sidelink grant in one SC period), in the first embodiment, the UE has more than one at a particular point in time (eg, within one SC period). Improve D2D communication by allowing it 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, and thus the number of valid sidelink grants possible in the UE during the SC period. Is limited by the maximum number of sidelink grant processes that the UE can run. Therefore, when a UE acquires a sidelink grant that has been addressed to a sidelink grant process that already has a sidelink grant, it overwrites the old sidelink grant with the newly acquired sidelink grant (to the currently standardized system). resemble).

According to one implementation of the first embodiment, the UE is allowed to have, for example, up to two sidelink grant processes so that the UE can handle two different sidelink grants at the same time. (Therefore, the UE has two valid sidelink grants within the SC period). Therefore, the sidelink grant process ID can have a size of 1 bit to allow the two sidelink grant processes to be distinguished. In another implementation of the first embodiment, the UE can launch more sidelink grant processes (eg, 4 or 8), which allows the UE to launch more sidelinks. Grants can be handled at the same time. However, the corresponding sidelink grant process ID has more bit sizes to allow the different sidelink grant processes to be distinguished. For example, in the case of a total of four side link grant processes, it is 2 bits, and in the case of a total of eight side link grant processes, it is 3 bits, and so on.

The maximum number of sidelink grant processes handled by the UE can be set, for example, by RRC, or can be predetermined (eg, determined within the corresponding 3GPP standard).

Overall, the UE performs D2D transmissions in each sidelink grant process within the same SC period, respectively, according to the already standardized concepts for performing D2D transmissions, eg, described in the Background Techniques section. In particular, for each sidelink grant available to the UE (ie, 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 their respective sidelink grants. For each sidelink grant available to the UE (ie, in each sidelink grant process), the UE identifies a sidelink destination group and a corresponding sidelink that identifies the radio resource allocated for the corresponding D2D transmission. It generates control information and performs D2D transmission of side link control information and corresponding data for each side link grant (process) using the assigned radio resources of each side link grant.

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

The above-mentioned principle underlying the first embodiment has various advantages. In this respect, the already established procedure can be reused without modification. For example, the same SCI format 0 can be used for the purpose of transmitting side link control information, because no additional information needs to be conveyed. Further, the receiving UE executes according to the first embodiment in one sidelink grant process because the D2D transmission in each sidelink grant process remains unchanged when compared to the currently standardized D2D transmission. There is no distinction between the D2D transmissions that are made and the D2D transmissions that are performed according to current standards (there is no need to actually make a distinction). Therefore, it is not necessary to adapt the behavior of the UE on the receiving side.

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

In addition to this, in the first embodiment, for example, by selecting different sidelink destination groups in each of the various sidelink grant processes, data destined for several sidelink destination groups will be sent to the same SC period. Can be sent within. Therefore, it is possible to avoid a resource shortage of a specific side link destination group.

So far, we have generally assumed that the UE has some sidelink grants available and have not paid attention to how the UE first acquired these sidelink grants. .. In fact, in the operation of the UE according to the principle of the first embodiment, the UE acquired the side link grant according to mode 1 (scheduled by eNB) or according to mode 2 (autonomous selection by UE). It doesn't matter. In other words, the first embodiment applies when each side link grant is acquired according to mode 1 or according to mode 2. Further, one side link grant can be scheduled in mode 1 and another side link grant can be scheduled in mode 2.

For mode 1, one or more based on the corresponding (s) requests from the UE (eg, scheduling requests or RACH procedures and corresponding buffer state information as described in the Background Techniques section). The side link grant is received from the eNB. In mode 1, each sidelink grant is received in a corresponding sidelink scheduling message sent by the eNB to the UE, which further adds the sidelink grant process to which the UE assigns the sidelink grant. Can be identified. For example, the corresponding sidelink grant process ID described above can be included by the eNB in the corresponding field of the sidelink scheduling message, in which case the UE will be assigned each sidelink grant to which the received sidelink grant should be assigned. The process can be identified using this sidelink grant process ID.

According to one implementation of the first embodiment, in this regard a new DCI format (typically referred to as DCI format 5a) can be introduced, which DCI format at least sideways within the corresponding field. Includes Link Grant Process ID. The number of bits in such a new field, including the sidelink grant process ID, is determined by the maximum total number of sidelink grant processes available to the UE. For example, a new sidelink grant process ID field can have 2 bits, which can distinguish a total of 4 sidelink grant processes.

In the new DCI format 5a, at least one or all of the following additional possible fields can be further expected.
− PSCCH resources − TPC commands for PSCCH and PSCH − The following fields of SCI format 0 ・ Frequency hopping flag ・ 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 in Non-Patent Document 3 (current version 12.4.0)). See section 1.9).

As mentioned above, in the prior art, the sidelink scheduling message used to send the sidelink grant is in DCI format 5 (see Background Techniques 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 in format 0 for scheduling the same serving cell, then the payload size in format 5 is added to the padding bits in format 0. Add 0 to format 5 until it is equal to the payload size of format 0 including. "

As is clear from this definition, "zero (0)" is added to DCI format 5 so that the payload size of DCI format 5 is equal to the payload size of DCI format 0 to facilitate blind decoding. .. According to a further implementation of the first embodiment, instead of introducing a new DCI, these padding bits (ie, "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 within the sidelink grant. In particular, some bits of any of the existing DCIs (eg DCI format 5) can be redefined for this purpose. In this case, some predefined (s) code points of at least one field transmitted within this DCI, or a combination of predefined code points of some fields is required. , This code point or combination of code points indicates that the remaining bits in the DCI are interpreted differently (ie, to indicate the sidelink grant process ID).

As mentioned above, the UE can perform several D2D transmissions within the same sidelink control period (eg, one per sidelink grant process). The various D2D transmissions performed by the 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, the radio resources used to transmit sidelink control information messages obtained from the corresponding transmit pools do not overlap in time. Similarly, the T-RPT pattern, which defines the timing of the first transmission of the MAC PDU and its retransmission, is appropriately selected so that the data transmissions of the two D2D transmissions do not overlap in time. The same applies to transmit resources for scheduling control information (SCI), i.e. 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 the UE in their respective sidelink scheduling messages. In contrast, for D2D transmissions scheduled in mode 2, when selecting resources from the corresponding pools, non-overlapping radio resources for various D2D transmissions (ie SCI and data) are selected so that they are selected. The UE itself handles it.

Instead, define, for example, a different SA_offset in each sidelink grant process to ensure that the SCI of each D2D transmission and the radio resources used to transmit the corresponding data do not overlap in time. Can be done. SA_offset is a parameter that defines the start of D2D transmission (see FIGS. 7 and 8) and therefore affects the start of SCI transmission and the next data transmission. In addition to this, for data transmissions scheduled in mode 2, different Mode2data_offset values can be used in different sidelink grant processes, which allows the same T-RPT bitmap to be used for data transmissions of different D2D transmissions. Even when using, it is possible to prevent data transmissions from overlapping in time.

FIG. 13 is a sequence diagram of UE operation for executing D2D transmission according to the first embodiment. The concept shown in FIG. 13 applies basically equally to the D2D transmission scheduled in mode 1 and the D2D transmission scheduled in mode 2, but the specifically shown sequence of steps is such that the UE eNBs the eNB. Applies to mode 1 (scenario scheduled by eNB) for receiving sidelink grants from. Further, for D2D transmissions scheduled in mode 2, the UE first selects the sidelink destination group (s) to which the data is transmitted, and then the UEs select the appropriate (s) appropriate (s). ) Get the corresponding (various) sidelink grants by autonomously selecting from the transmit radio resource pool. Based on the side link grant thus acquired, the side link control information and the corresponding side link data are generated and D2D transmission is executed.

As is clear from FIG. 13, in this exemplary scenario, N sidelink grant processes available in the UE are envisioned to handle the corresponding sidelink grants. N is 1 or more (N ≧ 1), but is less than or equal to the maximum number of side link 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 of the currently "active" sidelink grant process to handle each previously acquired sidelink grant. It is a number. That is, the UE has acquired 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 are essentially simultaneous so that these D2D transmissions are performed within the same SC period.

On the other hand, FIG. 14 shows the D2D communication timing in the case of the scenario scheduled in mode 1 during one SC period according to the first embodiment. FIG. 14 is based on the illustration already used in FIG. 8 and also shows the SA-offset time, after which the SC period begins and is shown in the sidelink grant received from the eNodeB. Scheduling quotas (sidelink control information) are sent using the corresponding outbound pool resource. Also in this exemplary scenario, it is exemplarily assumed that the same SCI message is retransmitted three times after the initial transmission of the SCI. The UE then initiates D2D data transmission in the next uplink subframe after transmitting the scheduling allocation. The MAC PDU is transmitted on its first transmission and (s) retransmissions set by the T-RPT (Time Resource Pattern of Transmission).

As is clear from FIG. 14, the UE has two sidelink grants, each addressed to a different sidelink grant process (in this exemplary case, the sidelink grant process with ID 1 and the side with ID 2). It is assumed that the link grant process) is received from the eNodeB. As described in connection with FIG. 13, the UE performs D2D transmission in each sidelink grant process (ie, in this case each of the two sidelink grants) for essentially the same sidelink control period (eg, SA_offset). It starts at the same time later and continues within the length of the side link control period). FIG. 14 illustrates this situation and shows two D2D transmissions of scheduling allocation and corresponding data performed by the transmitting user equipment. In the exemplary scenario assumed in FIG. 14, it is assumed that the upper D2D transmission is destined for a side link destination group different from the lower D2D transmission (although the two D2D transmissions are). It can also convey data from the same sidelink destination group).

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

FIG. 15 shows the D2D communication timing in the case of 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 in the Background Techniques section. Unlike the scenario of FIG. 14, it is assumed that the side link grant is not received from the radio base station and the two side link grants are autonomously selected by the UE. Similar to the illustration in FIG. 14, the radio resources for transmitting the side link control information and data of the two D2D transmissions do not overlap in time. In this case, the UE selects a corresponding resource that does not overlap in the time domain for transmitting the side link control information from SA_mode2_Tx_pool, and further, in two D2D transmissions, appropriately different T- for transmitting data. Select the transmit resource for the RPT bitmap and the corresponding control information (SCI).

14 and 15 show a scenario in which all available sidelink grants are either scheduled by eNodeB or autonomously selected. However, the UE can also have a valid (s) side link grant by mode 1 and a valid (s) side link grant by mode 2 at the same time.

In the above-described implementation of the first embodiment, it is assumed that the UE determines the side link destination group in which the D2D transmission is executed within the same SC period, and no further detailed description is given. According to a particular implementation of the first embodiment, the step of determining a sidelink destination group is performed by using a (one or more) logical channel prioritization (LCP) procedure.

According to one alternative form, one LCP procedure is performed for each sidelink grant process (or a valid sidelink grant), thus the UEs individually separate the sidelink destination groups in each sidelink grant process. select. As explained in the Background Technology section, the current standard does not specify the order in which sidelink logical channels are processed and is left to the UE implementation: destination group selection and selection. The order in which the side-link logical channels belonging to the given destination group are processed is unspecified, and no prioritization mechanism is implemented. However, in this implementation, it is assumed that the priorities corresponding to each side link destination group are associated. According to this implementation, the UE performs the LCP procedure individually for each sidelink grant process. More specifically, the UE performs the LCP procedure continuously, i.e., for example, starting with the LCP procedure for the first side-link grant process, then performing the LCP procedure for the second side-link grant process, and so on. The same is true. In each LCP procedure, the UE selects the sidelink destination group that has the available data and has the highest corresponding priority. Therefore, if the UE has data available for transmission in two different destination groups, the higher priority sidelink destination after performing the first LCP procedure (according to the first sidelink grant). If the group's data still exists in its own buffer, the UE reselects the same sidelink destination group in the second LCP procedure.

According to a further alternative, the UE performs a common LCP procedure for all sidelink grant processes (or valid sidelink grants), so the UE can set sidelink destination groups in all sidelink grant processes. , Choose in an interdependent way. In this implementation as well, it is assumed that the priorities corresponding to each destination group are associated. According to this implementation, destination group selection is performed in descending order of destination group priority. Specifically, again assuming that the UE has data available for transmission of two different destination groups, the first side of the destination group with the higher priority is the first side. Use link grants. However, the second sidelink grant has the lower priority of the destination group, even if there is still available data to be sent to the destination group with the higher priority of the destination group. Used for destination groups. If additional destination groups exist, additional sidelink grants are used as well.

<Second embodiment>
Hereinafter, the second embodiment for solving the above-mentioned problem will be described in detail. The main concept of the second embodiment is different from the concept of the first embodiment. However, scenarios (s) for explaining the underlying principles of the second embodiment can be similarly envisioned. In particular, assume a ProSe-enabled UE, and thus this UE can perform (one or more) D2D transmissions directly with another (one or more) UEs without going through the eNodeB. .. Further, the UE shall have data available for transmission, destined for multiple sidelink destination groups, where the improved D2D transmission according to the second embodiment is one sidelink in the UE. It also applies equally if the data for the destination group only is available for transmission.

According to the second embodiment, the D2D transmission is improved by enhancing the side link control information so that it can identify not only one side link destination group but also a plurality of side link destination groups. Therefore, the D2D transmission performed by the UE can convey data for a plurality of sidelink destination groups identified by the corresponding sidelink control information. The radio resources for performing D2D transmission (of sidelink control information and corresponding data) are defined by the 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 the 3GPP standard. Therefore, according to the second embodiment, no change is necessary in this respect.

In addition, the UE (having available data for multiple sidelink destination groups) selects a particular sidelink destination group (at least two) of the sidelink destination groups, and then the selected destination groups. Generates appropriate sidelink control information to identify, and generates a corresponding data packet for D2D transmission, in which case the data packet conveys data from some determined sidelink destination group. The UE can transmit data of a plurality of different side link destination groups in one D2D transmission within one SC period, and the plurality of different side link destination groups are transmitted at the beginning of the D2D transmission. Identified by side link control information.

FIG. 16 shows a sequence diagram of the behavior of the UE when performing D2D transmission according to the second embodiment, that is, the step described above, that is, the step of acquiring the side link grant, and a plurality of side link destination groups. A step of determining, a step of generating side link control information that identifies a plurality of side link destination groups, and a step of generating a data packet that conveys data to a plurality of selected side link destination groups. It includes a step of finally executing a D2D transmission of the generated side link control information and corresponding data to a plurality of side link destination groups. Although FIG. 16 shows a particular order of steps for illustration purposes, the second embodiment is not limited to this particular order, and other suitable orders are possible as well. For example, the steps to determine different sidelink destination groups can be performed before the step to obtain the sidelink grant, or the sequence of steps to generate sidelink control information and steps to generate data packets. Can be reversed.

On the other hand, FIG. 17 shows the D2D communication timing of 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 in FIG. 8 already used in the Background Techniques section. As is clear from FIG. 17, the difference is that according to the second embodiment, each MAC PDU (and its retransmission) can convey data destined for different sidelink destination groups (FIG. 17). In this particular example of, data destined for three different sidelink destination groups is transmitted within the SC period), whereas in the currently standardized system according to FIG. 8, the MAC PDUs are the same. Communicate data for sidelink destination groups (although the actual data in the various MAC PDUs varies from MAC PDU). Although not shown in FIG. 17, assuming that the UE has selected only two different sidelink destination groups for D2D transmission, the first MAC PDU (and its retransmissions) will transmit the first sidelink destination group. The destination data can be transmitted, the second MAC PDU (and its retransmission) can convey the data destined for the second sidelink destination group, and the third MAC PDU (and its retransmission) can be transmitted. Transmission) can again convey data destined for the first sidelink destination group.

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

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

According to a different implementation of the second embodiment, the side link control information message directly identifies (ie, includes a plurality of corresponding IDs) a plurality of side link destination groups, as described in detail below. Or indirectly (ie, by including one ID associated with multiple sidelink destination groups).

According to the first implementation of the second embodiment, the side link control information message transmitted as part of the D2D transmission includes one side link destination group ID per determined side link destination group. In other words, the side link control information message directly identifies the side link destination group by including the corresponding identifying information of the side link destination group. Therefore, the side link control information message can include two or more side link destination group IDs.

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 exemplified by an already standardized SCI format (as defined in section 5.4.3.1.1 of Non-Patent Document 3 (current version 12.4.0)). It can be based on 0, but in addition it can indicate some sidelink destination group IDs (referred to as "group destination IDs" in the standard). Thus, the novel SCI format 1 more specifically includes one or more of the following fields, corresponding to the already standardized SCI format 0 of Non-Patent Document 3.
− Frequency hopping flag − Resource block allocation and hopping resource allocation − Time resource pattern − Modulation coding method − Timing advance instruction

For example, instead of providing 8 bits for the group destination ID as in the currently standardized SCI format 0, the new SCI format 1 corresponds to two group destination IDs (ie, two sidelink destination group IDs). ), So it has 16 bits available. Of course, if the sidelink control information message should be able to convey more sidelink destination group IDs, then more bits must be provided in this regard (eg, three different). 24 bits for side link destination group IDs, 32 bits for four different side link destination group IDs).

As an option in this first embodiment of the second embodiment, the receiving UE recognizes the side link destination group ID referenced by the corresponding transport block in the D2D transmission. In other words, the receiving UE recognizes which transport block is carrying the data of which sidelink destination group identified in the SCI. This exemplifies a predetermined unique relationship (ie, rule) between the order of the side link destination group IDs in the SCI and the order of the corresponding transport blocks in the next part of the D2D transmission. ) Can be done. For example, the order of the (s) group destination IDs (ie, sidelink destination group IDs) in the SCI is a transport that conveys the data of the corresponding transport block (ie, each sidelink destination group) transmitted in the D2D transmission. It can correspond to the order of blocks). For example, when the first group destination ID in the SCI points to the destination A and the second group destination ID points to the destination B, there are two transport blocks transmitted within the SC period. In the case, 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 transmitted within the SC period, the third transport block contains, for example, data again destined for group A, and so on. In essence, the receiving UE recognizes the group destination ID of the corresponding transport block within the SCI period according to some predefined rule. When implementing this option in the currently defined 3GPP environment, the receiving UE will have (one or more) of the data in the transport block based on the group destination ID in the SCI and the predefined rules. Recognizes the 8 least significant bits (LSB) of the destination layer 2 ID. As a result, the UE can filter D2D transmissions (especially MAC PDUs) according to the sidelink destination group of interest, so the receiving UE can actually contain the data of the sidelink destination group of interest. Decrypt only the PDU. More specifically, if the DST field of the decrypted MAC PDU subheader is equal to any 16 MSBs of any of the UE's (s) destination Layer 2 IDs, the PDU is further processed in the UE. ..

According to the alternative implementation, the DST field of the MAC PDU subheader contains 24 MSBs (eg, full 24 bits) of the destination layer 2 ID. The receiving UE can uniquely identify the destination Layer 2 ID of the data in the transport block based on these 24 bits in the MAC subheader and can therefore 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 transmitted in the D2D transmission. For example, if there are two transport blocks to be transmitted within the SC period, even if the first group destination ID points to destination A and the second group destination ID points to destination B. The first transport block can contain data destined for group B and the second transport block contains 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, that is, the receiving UE can only filter packets of interest based on the destination Layer 2 ID. It can be decrypted.

According to the second alternative implementation of the second embodiment, the side link control information message transmitted as part of the D2D transmission contains only one ID, however, this ID is a plurality of determined side links. Associated with a destination group. As a result, instead of directly identifying the sidelink destination group by including its respective corresponding identifying information, the sidelink destination group is indirectly identified by the appropriate ID, and this ID is again multiple sides on the receiving side. Can be associated with a link destination group.

Specifically, this second alternative implementation introduces a new ID, which is transmitted in place of the sidelink destination group ID and is associated with a plurality of sidelink destination groups. In other words, this new ID (hereinafter exemplarily referred to as a broadcast ID) is a many-to-one combination of different sidelink destination groups 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 the appropriate node in the core network (eg ProSe server function). Therefore, since the ProSe server function associates some side link destination groups with each broadcast ID, such a mapping function can be executed. In this case, the corresponding mapping information (ie, the broadcast ID and the correspondingly associated sidelink destination group) is also provided to the UE and optionally the eNodeB. The provision of this information can be performed, for example, using RRC signaling, or can be broadcast in the system information by various eNodeBs.

In one variation, the new broadcast ID is the same size as the side link destination group ID normally used to identify the side link destination group in the side link control information, i.e. 8 bits (background). (See section of technology), therefore, the already defined sidelink control information format 0 can be reused without conforming. Alternatively, the new broadcast ID can be of a different (eg, larger) size than the commonly used sidelink destination group ID, in which case the new broadcast ID will be conveyed to convey the new broadcast ID. A sidelink control information format is required.

Based on the second alternative implementation of the second embodiment, the UE determines a plurality of side link destination groups to which data is transmitted in the D2D transmission according to a valid side link grant, and then these determined plurality. The corresponding broadcast ID associated with the sidelink destination group of is further determined. The UE can then include the determined broadcast ID in the side link control information for D2D transmission instead of one or more IDs in the side link destination group.

On the other hand, the UE that receives the D2D transmission including the side link control information including the broadcast ID has a plurality of sides from the received broadcast ID based on the mapping information previously received and stored, for example, from the ProSe server function. Find the link destination group.

According to the 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 side link control information message can include appropriate information (such as flags) as to whether the control information message contains a new broadcast ID or a normal side link destination group ID. In this case, a new side link control information format that further includes this flag may be required. Therefore, the sending UE includes itself a broadcast ID (when data of some sidelink destination groups is transmitted in the D2D transmission) or a normal sidelink destination group ID (in the D2D transmission). When data of only one side link destination group is transmitted), the corresponding flag is set. On the other hand, the receiving UE considers the value of this flag when determining which (one or more) sidelink destination groups the received D2D is actually destined for.

Up to this point, the two alternative implementations of the second embodiment have been described, but in each of these implementations, the side link control information can identify a plurality of side link destination groups when necessary.

Therefore, the UE having data available for transmission of some side link destination groups determines the side link destination group to transmit the data by the next D2D transmission among these plurality of side link destination groups. .. Then, in order to identify the plurality of determined side link destination groups, one suitable broadcast ID is included by including some IDs according to the first alternative implementation described above, or according to the second alternative implementation described above. Generate the corresponding side link control information message by including.

In addition, 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 during the SC period can convey data destined for the first sidelink destination group and is generated by the UE during the SC period 2 The second transport block can carry data destined for the second sidelink destination group, and so on. This is easily understood from the illustration in FIG.

However, the number of sidelink destination groups that can transmit data 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 selected T-RPT bitmap could transmit three individual MAC PDUs within one SC period. It can, therefore, allow the UE to transmit data destined for up to three sidelink destination groups. More or fewer sidelink destination groups transmitted within one SC period by setting different lengths of SC period or selecting different T-RPT patterns (eg, fewer retransmissions) Can be determined.

In the above example, the UE determines the (three) different destination groups to which the data is transmitted by the D2D transmission, but the same destination group (s) can also be selected by the UE respectively.

For further details on the various steps performed by the UE to successfully perform a D2D transmission, see the corresponding section within the Background Technology section, which is omitted here.

The corresponding operation on the receiving side is to be able to receive a D2D transmission that includes data destined for several sidelink destination groups. The receiving UE identifies some sidelink destination groups from the sidelink control information message (group destination ID) and therefore whether or not it is interested in its D2D transmission (ie, the UE is an SCI within the D2D transmission). Are you interested in receiving data to one or more of the sidelink destination groups identified by the identifier in?). 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, in order to determine whether the receiving UE wants to receive and decrypt the data in the MAC PDU, the receiving UE includes a step of obtaining a side link destination group for each MAC PDU for D2D transmission. Can be done.

For example, according to the currently standardized procedure for transmitting a MAC PDU in a sidelink D2D transmission, as defined in Section 6.2.4 of Non-Patent Document 5 (current version 12.5.0), MAC. The header contains information about the sidelink destination group of the contained data. In particular, 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 side link destination group by these bits. The currently standardized SCI message contains the 8 least significant bits of the destination layer 2 ID, and the combination of these 8 LSBs and the 16 MSBs in the MAC header causes the receiving UE to sidelink. The destination group (that is, the destination layer 2 ID) can be uniquely identified. Thus, the receiving UE can filter D2D transmissions (especially MAC PDUs) according to the sidelink destination group that it is interested in, and thus the receiving UE is of the sidelink destination group that it is actually interested in. Decrypt only the MAC PDU that contains the data. More specifically, if the DST field of the decrypted MAC PDU subheader is equal to any 16 MSBs of any of the UE's (s) destination Layer 2 IDs, the PDU is further processed in the UE. ..

According to one implementation, the DST field of the MAC PDU subheader is not only the 16 MSBs of the destination layer 2 ID as currently standardized, but the 24 MSBs of the destination layer 2 ID (eg, full 24 bits). including. The receiving UE can uniquely identify the destination Layer 2 ID of the data in the transport block based on these 24 bits in the MAC subheader and can therefore perform MAC filtering. This method 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 has a group destination ID (ie, a corresponding within the SC period). This is because the eight LSBs of the destination layer 2 ID of the transport block are not recognized. What the receiving UE recognizes based on the broadcast ID basically includes data in which the transport block within the SC period has one of the group destination IDs mapped to the broadcast ID as the destination. It's just that you can. For example, when the group destination ID = "0" and the group destination ID = "1" are mapped to the broadcast ID = "0", the receiving UE has the group destination ID = as the first transport block in the SC period. It does not recognize whether it has "0" or group destination ID = "1". The same applies to other transport blocks during 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 has the complete destination Layer 2 ID of the data in the transport block. It cannot be uniquely identified (because the receiving UE does not recognize the eight LSBs (Group Destination IDs) of the destination layer 2 IDs).

The above description of the second embodiment assumes that the UE has valid sidelink grants, but does not detail how the UE acquired these valid sidelink grants. In the operation of the UE according to the principle of the second embodiment, it is important whether the UE acquires the side link grant according to mode 1 (from eNB) or according to mode 2 (R2 autonomously selected by the UE). is not it. Therefore, the second embodiment applies to both the side link grant acquired in mode 1 and the side link grant acquired in mode 2. Specifically, in mode 1, the sidelink grant is based on, for example, a corresponding request from the UE (eg, a scheduling request or RACH procedure and corresponding buffer state information as described in the Background Techniques section). It was received from. For more information on these steps and the corresponding sidelink scheduling messages sent from the eNodeB to the UE, see the corresponding sections in the Background Technology section, which are omitted here. In mode 2, the sidelink grant is autonomously selected by the UE from the corresponding transmit radio resource pool for transmitting scheduling control information and data. Details on these procedures in Mode 2 are also omitted here, but see the corresponding sections in the Background Techniques section.

In the above-described implementation of the second embodiment, it has been described that the UE determines a plurality of side link destination groups to which D2D transmission is executed within the SC period, but no further details are shown. .. According to a particular implementation of the second embodiment, the step of determining multiple sidelink destination groups is performed by the UE by using a (single or multiple) logical channel prioritization (LCP) procedure. Can be done. In particular, the UE can determine in the LCP procedure which sidelink destination group data should be transmitted.

According to an alternative embodiment of the second embodiment, the UE is allowed to send data to a plurality of different sidelink destination groups as long as the corresponding group destination IDs (transmitted in the SCI) are the same. Will be done. More specifically, according to current standards, the group destination ID transmitted within the SCI on the physical sidelink control channel is the eight least significant bits (LSB) of the destination layer 2 ID. As long as the UE multiplexes the logical channels within the PDU of the source layer 2 ID and the destination layer 2 ID pair (the eight LSBs of the destination layer 2 ID are the same), the UE has one SC period. Data can be sent to several different sidelink destination groups within. This implementation does not require substantial changes to the currently standardized procedures. Since the group destination IDs are the same, the target receiving UE does not fail to receive the corresponding data transmission on the SL-DCH. As an example, the transmitting UE transmits data to which the destination layer 2 ID = "11111111111111111000000" and the side link destination group having the destination layer 2 ID = "111111111111111100000000" are the destinations within one SC period. This is because the eight LSBs are the same in both cases (in this case the group destination ID transmitted in the SCI is "00000000000").

<Implementation of this disclosure by hardware and software>
Another exemplary embodiment relates to implementing the various embodiments described above using hardware, software, or software that works with the hardware. In this regard, 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.

Various embodiments are further recognized as being able to be implemented or performed using a computing device (processor). Computing devices or processors include, for example, general purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or other programmable logic devices. Various embodiments may also be implemented or embodied by a combination of these devices. In particular, each functional block used in the description of each embodiment described above can be implemented by an LSI as an integrated circuit. These functional blocks can be formed individually as chips, or one chip can be formed so as to include a part or all of the functional blocks. These chips can include a data input / output unit that is coupled to them. LSIs are also referred to as ICs, system LSIs, super LSIs, or ultra LSIs, depending on the degree of integration. However, the technique for implementing an integrated circuit is not limited to LSI, and can be achieved by using a dedicated circuit or a general-purpose processor. Further, an FPGA (field programmable gate array) that can be programmed after manufacturing the LSI, or a reconfigurable processor that can reset the connection and setting of the circuit cells arranged inside the LSI can also be used.

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

Those skilled in the art will appreciate that the disclosure presented in a specific embodiment may be modified and / or modified in various ways without departing from the broadly defined concept or scope of the invention. Will be done. Therefore, the embodiments presented herein are considered exemplary in all respects and are not intended to limit the invention.

Claims (6)

An integrated circuit that controls a transmitting user device that executes direct communication transmission through a direct side link connection to one or more receiving user devices in a communication system.
The process of receiving at least two sidelink grants that handle direct communication transmissions executed within the same transmission control period, and
At least one of each of the two sidelink grant processes is associated with the identity information.
• Correspondingly associate each of the at least two received sidelink grants with one of each of the at least two sidelink grant processes.
• In each of the at least two sidelink grant processes, radio resources for performing direct communication transmission of sidelink control information and data through the direct sidelink connection are allocated according to the respective sidelink grants.
An integrated circuit comprising a process of executing a direct communication transmission within the same transmission control period for each sidelink grant process having the correspondingly associated sidelink grant. The sending user equipment are available for transmission, and a buffer for storing data of which destination is a plurality of side links destination group, respectively, provided with a processor is associated with said corresponding manner For each sidelink grant process that has a sidelink grant
-Each side link destination group is determined as a destination for direct communication transmission using wireless resources according to each side link grant.
-For each of the determined side link destination groups, side link control information that identifies the radio resource allocated to execute the direct communication transmission is generated.
The direct communication transmission of the generated side link control information and data to each of the determined side link destination groups as a destination, using the radio resources indicated by the respective side link control information. Execute within the same transmission control period, control processing,
The integrated circuit according to claim 1. The transmitting user device
• Use a common logical channel prioritization procedure to determine all said sidelink destination groups for all said received sidelink grants, or
· Use a separate logical channel prioritization procedure for each sidelink grant received,
By controlling the process, determining one sidelink destination group per received sidelink grant.
The integrated circuit according to claim 2. Each of said at least two side links grant, received from the radio base station by the receiving unit, or is autonomously selected from a transmitting radio resource pool by a processor of the sending user equipment,
When the side link grant is received from the radio base station, the receiving unit of the transmitting user device is configured to receive the side link grant by the side link scheduling message, and is based on the side link scheduling message. , Acquires identification information, which identifies the sidelink grant process in the transmitting user device, to which each of the sidelink grants should be associated.
The side link scheduling message received by the transmitting user device further includes information about the content of the side link control information to be transmitted by the transmitting user device, and the side in the direct communication transmission. Link control Indicates the radio resource, which should be used to transmit information and data, controls processing,
The integrated circuit according to any one of claims 1 to 3. The transmission process transmits the data using the next uplink subframe of the radio resource used to transmit the sidelink control information.
The integrated circuit according to any one of claims 1 to 4. The number of parallel executables of the sidelink grant process is eight.
The integrated circuit according to any one of claims 1 to 5.

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