JP2019126092A - Improved resource allocation in device-to-device (d2d) communication - Google Patents

Abstract

To allocate radio resources to a transmission side terminal for executing direct communication transmission through direct link connection.SOLUTION: A transmission side terminal receives system information broadcast from a base station. The system information broadcast includes information on a temporary transmission radio resource pool indicating radio resources for executing direct communication transmission and setting information on a resource pool to limit time length when a transmission side terminal can use the temporary radio resource pool.SELECTED DRAWING: Figure 18

Description

  The present disclosure relates to a method of allocating radio resources to a transmitting terminal for performing direct communication transmission through a direct link connection with the receiving terminal. Furthermore, the present disclosure provides transmitting terminals and base stations involved in the method described herein.

[LTE (Long Term Evolution)]
Third generation mobile communication systems (3G) based on WCDMA® radio access technology are being deployed on a wide scale in the world. High-speed downlink packet access (HSDPA) and enhanced uplink (high-speed uplink packet access (HSUPA: high-speed packet access (HSUPA)) are the first steps in enhancing, evolving and evolving this technology. (Also referred to as Uplink Packet Access), which provides a very competitive wireless access technology.

  In order to respond to the ever-increasing demand from users and to secure competitiveness against new radio access technologies, 3GPP has introduced a new mobile communication system called LTE (Long Term Evolution). LTE is designed to provide the carriers required for high speed transmission of data and media and high capacity voice support for the next 10 years. The ability to provide high bit rates is an important measure in LTE.

  The specifications of work items (WI) for Long Term Evolution (LTE) are referred to as E-UTRA (Evolved UMTS Terrestrial Radio Access) and E-UTRAN (Evolved UMTS Terrestrial Radio Access Network), and finally release 8 Released as (LTE release 8). The LTE system is a packet-based efficient radio access and radio access network, providing full IP-based functionality with low latency and low cost. In LTE, scalable transmission bandwidths (eg, 1.4 MHz, 3.0 MHz, 5.0 MHz, 10.0 MHz, 15.0 MHz, etc.) to achieve flexible system deployment using a given spectrum And 20.0 MHz) are specified. For downlink, radio access based on OFDM (Orthogonal Frequency Division Multiplexing) is adopted. Because such wireless access is inherently less susceptible to multi-path interference (MPI) due to low symbol rate, and also uses cyclic prefix (CP), and various transmissions. This is because it can cope with the bandwidth configuration. For uplink, radio access based on SC-FDMA (Single-Carrier Frequency Division Multiple Access) is adopted. This is because, given the limited transmission power of the user equipment (UE), it is prioritized to provide a wider coverage area than to improve the peak data rate. In LTE Release 8/9, a number of key packet radio access technologies (eg, Multiple-Input Multiple-Output (MIMO) channel transmission technology) are employed to achieve a highly efficient control signaling structure.

[LTE architecture]
FIG. 1 shows the overall architecture of LTE, and FIG. 2 shows the architecture of E-UTRAN in more detail. The E-UTRAN is configured of an eNodeB, and the eNodeB terminates a user plane (PDCP / RLC / MAC / PHY) protocol and a control plane (RRC) protocol of E-UTRA directed to user equipment (UE: User Equipment). The eNodeB (eNB) is a physical (PHY) layer, a medium access control (MAC) layer, a radio link control (RLC) layer, and a packet data control protocol (PDCP) layer (These layers host user plane header compression and encryption functions). The eNB also provides a Radio Resource Control (RRC) function corresponding to the control plane. The eNB performs radio resource management, admission control, scheduling, implementation of uplink quality of service (QoS) by negotiation, broadcast of cell information, encryption / decryption of user plane data and control plane data, downlink Perform many functions, such as compression / decompression of / uplink user plane packet headers. The plurality of eNodeBs are connected to each other by the X2 interface.

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

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

Component carrier structure in LTE
The downlink component carriers of the 3GPP LTE system are further divided in the time-frequency domain in so-called subframes. In 3GPP LTE, each subframe is divided into two downlink slots as shown in FIG. 3, in which the first downlink slot covers the control channel region (PDCCH region) in the first OFDM symbol Prepare. Each subframe is composed 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 spans the entire bandwidth of the component carrier. Thus, the OFDM symbols are each composed of several modulation symbols transmitted on N ^DL _RB × N ^RB _sc respective subcarriers, as also shown in FIG.

For example, assuming a multi-carrier communication system using OFDM as used in 3GPP LTE, the smallest unit of resources that can be allocated by the scheduler is one "resource block". A physical resource block (PRB: Physical Resource Block) is, as illustrated in FIG. 4, N ^DL _symb consecutive OFDM symbols in the time domain (eg, seven OFDM symbols) and N ^RB in the frequency domain. It is defined as _sc continuous subcarriers (eg, 12 subcarriers of component carriers). Therefore, in 3GPP LTE (Release 8), a physical resource block is configured of N ^DL _symb × N ^RB _sc resource elements corresponding to one slot in the time domain and 180 kHz in the frequency domain (downlink resource grid For further details, see, eg, Section 6.2 of Non-Patent Document 1 which is available on the 3GPP web site and is incorporated herein by reference).

One subframe consists of two slots, so there are 14 OFDM symbols in the subframe when the so-called "normal" cyclic prefix (normal CP) is used, the so-called "extended" cyclic When the prefix (extended CP) is used, 12 OFDM symbols are present in a subframe. As a terminology, in the following, a time-frequency resource equal to the same N ^RB _sc consecutive subcarriers across subframes is referred to as a 'resource block pair', or 'RB pair' or 'PRB (physical Resource block) called "pair".

  The term "component carrier" means the combination of several resource blocks in the frequency domain. In future releases of LTE, the term "component carrier" will no longer be used, but instead its terminology will be changed to "cell" indicating a combination of downlink 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 on the downlink resource.

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

[Carrier aggregation in LTE-A to support wider bandwidth]
At the World Wireless 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 varies by region and country. However, following the determination of the outline of the available frequency spectrum, standardization of the air interface was started in 3GPP. In 3GPP, at the 3GPP TSG RAN # 39 meeting, the description of the study item (Study Item) on “Further Advancements for E-UTRA (LTE-Advanced)” was approved. This examination item covers technical elements to be considered in the evolution and development of E-UTRA (for example, in order 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 wireless spectrum is a bottleneck in the development of wireless networks, and as a result, it is difficult to find a sufficiently wide spectrum band for the LTE advanced system. Therefore, it is urgent to find a way to obtain a wider radio spectrum band, where the possible answer is the carrier aggregation function.

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

  All component carriers can be configured as LTE Release 8/9 compatible when the number of aggregated component carriers is at least the same for uplink and downlink. All component carriers aggregated by the user equipment may not necessarily be LTE Release 8/9 compatible. Existing mechanisms (eg, barring) can be used to prevent the release 8/9 user equipment from camping on the component carrier.

  The user equipment may simultaneously receive or transmit one or more component carriers (corresponding to multiple serving cells) depending on its capabilities. The LTE-A Release 10 user equipment with the reception and / or transmission capabilities for carrier aggregation can simultaneously receive and / or transmit on multiple serving cells, On the other hand, LTE Release 8/9 user equipment can receive and transmit on only one serving cell if the structure of the component carrier conforms to the release 8/9 specification.

  Carrier aggregation is supported on both contiguous and non-contiguous component carriers, where each of the component carriers is up to 110 in the frequency domain when using the 3GPP LTE (Release 8/9) calculation scheme. Limited to resource blocks.

  Configure 3GPP LTE-A (Release 10) compatible user equipment to aggregate different number of different component carriers of different bandwidths, possibly from uplink and downlink, sent from the same eNodeB (base station) It is possible. The number of downlink component carriers that can be configured depends on the downlink aggregation capability of the user equipment. Conversely, the number of uplink component carriers that can be configured depends on the uplink aggregation capability of the user equipment. The mobile terminal can not be configured 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 the downlink. Component carriers transmitted from the same eNodeB do not necessarily have to provide the same coverage.

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

  The impact of aggregating multiple carriers only affects the MAC layer. In the MAC layer, one HARQ entity is required per aggregated component carrier in both uplink and downlink. There is at most one transport block per component carrier (when not using SU-MIMO in the uplink). The transport block and its HARQ retransmission (when it occurs) needs to be mapped to the same component carrier.

  FIG. 5 and FIG. 6 show L2 layer structure in which carrier aggregation is configured in downlink and uplink, respectively.

  When carrier aggregation is configured, the mobile terminal only has one RRC connection with the network. At RRC connection establishment / re-establishment, one cell has security inputs (one ECGI, one PCI, and one ARFCN) and non-access layer (NAS) mobility information (NAS), as in LTE Release 8/9. Example: TAI) is provided. After RRC connection establishment / re-establishment, the component carrier corresponding to that cell is referred to as a downlink primary cell (PCell). In the connected state, one downlink PCell (DL PCell) and one uplink PCell (UL PCell) are always configured per user equipment. A cell other than the primary cell in the set of component carriers is referred to as a secondary cell (SCell), and the carriers of SCell are a downlink secondary component carrier (DL SCC) and an uplink secondary component carrier (UL SCC) It is.

  Configuration and reconfiguration of component carriers, and addition and deletion can be performed by RRC. Activation and deactivation takes place via the MAC control element. At the time of intra-LTE handover, RRC can also add, delete, or reconfigure SCells for use in the target cell. When adding a new SCell, the system information of the SCell (this information is required for transmission / reception) is sent using dedicated RRC signaling (as at handover in LTE Release 8/9).

  When the user equipment is configured to use carrier aggregation, a pair of uplink component carriers and downlink component carriers is always active. The downlink component carrier of this pair may also be referred to as the "downlink anchor carrier". The same applies to the uplink.

  When carrier aggregation is configured, user equipment can be scheduled for multiple component carriers at the same time, but at most one random access procedure can be performed at one time. In cross-carrier scheduling, resources of another component carrier can be scheduled by PDCCH of the component carrier. For this purpose, a component carrier identification field (referred to as "CIF") has been introduced in each DCI format.

  When cross carrier scheduling is not performed, linking uplink component carriers and downlink component carriers can identify uplink component carriers to which a grant is applied. The links of the downlink component carrier to the uplink component carrier do not necessarily have to be one to one. In other words, multiple 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.

[RRC state in LTE]
LTE is based on only two main states: "RRC_IDLE" and "RRC_CONNECTED".

  In the RRC_IDLE state, the radio is not active but is assigned and tracked by the network. More specifically, the mobile terminal in the RRC_IDLE mode performs cell selection and reselection (in other words, determines a cell to camp on). In the cell (re) selection process, each applicable radio access technology (RAT) radio resource priority, radio link quality, and cell status (ie cell barred or reserved) Is considered. The mobile terminal in the RRC_IDLE mode monitors the paging channel to detect an incoming call, and further acquires system information. The system information mainly consists of parameters for the network (E-UTRAN) to control the (re) selection process of the cell and how the mobile terminal accesses the network. The RRC specifies control signaling (ie paging and system information) to be applied to the mobile terminal in RRC_IDLE state. The behavior of the mobile terminal in the RRC_IDLE state is defined in more detail in section 4 “General description of Idle mode” (incorporated herein by reference) of Non-Patent Document 2.

  In the RRC_CONNECTED state, the mobile terminal has an active radio operation with the eNodeB. In E-UTRAN, radio resources are allocated to mobile terminals so that (unicast) data can be transmitted via a shared data channel. To support this operation, the mobile terminal monitors the corresponding control channel used to indicate dynamic allocation of time and frequency shared transmission resources. The mobile terminal provides the network with its buffer status and downlink channel quality reports and measurement information of neighboring cells so that the E-UTRAN can select the optimal cell for the mobile terminal. These measurement reports include cells using another frequency or radio access technology (RAT). Furthermore, the user equipment receives system information which is mainly composed of the information required to use the transmission channel. User equipment in the RRC_CONNECTED state may be configured to use a discontinuous reception (DRX) cycle to extend the life of its battery. RRC is a protocol for the E-UTRAN to control the behavior of user equipment in the RRC_CONNECTED state.

  The various functions (including connection mode) of the mobile terminal in the RRC protocol are described in Section 4 "Functions" (incorporated herein by reference) of Non-Patent Document 3.

[Uplink access method in LTE]
Uplink transmissions require power efficient transmission by the user terminal to maximize coverage. As the uplink transmission scheme of E-UTRA, a scheme combining single carrier transmission and FDMA of dynamic bandwidth allocation is selected. The main reason for choosing single carrier transmission is the lower peak to average power ratio (PAPR) compared to multicarrier signal (OFDMA) and the corresponding improvement in the efficiency of the power amplifier And the improvement in coverage is expected (the data rate is higher than the given terminal peak power). At each time interval, the Node B assigns a unique time / frequency resource for transmitting user data to the user, thereby ensuring orthogonality in the cell. Orthogonal multiple access in the uplink increases spectral efficiency by eliminating intra-cell interference. Interference due to multipath propagation is dealt with in the base station (Node B) by inserting a cyclic prefix into the transmission signal.

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

[Uplink scheduling scheme in LTE]
As an uplink scheme, both scheduling controlled (ie, controlled by eNB) and contention based access can be used.

  In case of scheduling controlled access, specific frequency resources of a specific length of time (i.e. time / frequency resources) for transmitting uplink data are allocated to the user equipment. However, some time / frequency resources can be allocated for contention based access. Within the context of contention based time / frequency resources, user equipment may transmit without being initially scheduled. One scenario in which the user equipment performs contention based access is, for example, random access, ie when the user equipment performs the first access to a certain cell, or the first access to request uplink resources. It is time to do it.

For scheduling controlled access, the Node B's scheduler assigns users unique frequency / time resources for uplink data transmission. More specifically, the scheduler determines the following:
・ Allows transmission (one or more) user equipment ・ Physical channel resource (frequency)
-Transport format that the mobile terminal should use for transmission (MCS (Modulation and Coding Scheme))

  The assignment information is signaled to the user equipment via a scheduling grant sent on the L1 / L2 control channel. In the following, this channel is referred to as uplink grant channel for the sake of simplicity. The scheduling grant message includes, as information, at least a portion of the frequency band that is permitted to be used by the user equipment, a grant validity period, and a transport format that the user equipment must use for uplink transmission to be performed from now on. included. The shortest lifetime is one subframe. The grant message may also include additional information depending on the scheme selected. Only “for each user equipment” grant is used as the grant to grant the right to transmit on the uplink shared channel (UL-SCH) (ie there is no “for each radio bearer at each user equipment”) . Therefore, the user equipment needs to allocate allocated resources among the radio bearers according to some rules. Unlike the case of HSUPA, the transport format is not selected on the user equipment side. The eNB determines the transport format based on some information (eg reported scheduling information and QoS information), and the user equipment has to comply with the selected transport format. In HSUPA, the Node B allocates the maximum uplink resources and the UE selects the actual transport format for data transmission accordingly.

Since scheduling of radio resources is the most important function in shared channel access network in determining quality of service, uplink scheduling scheme in LTE satisfies for the purpose of enabling efficient quality of service (QoS) management. There are several requirements to be done.
• Resource shortages for low priority services should be avoided.
Quality of Service (QoS) should be clearly distinguished in each radio bearer / service.
・ Enables fine-grained buffer reporting (eg report per radio bearer or report per radio bearer group) in uplink reporting so that eNB scheduler can identify which radio bearer / service data is sent Should be
It should be possible to clearly distinguish quality of service (QoS) between services of different users.
It should be possible to provide a minimum bit rate per radio bearer.

  As can be understood from the conditions listed above, one important aspect of LTE's scheduling scheme is that operators control the distribution of their total cell capacity among individual radio bearers of different QoS classes To provide a mechanism that can The QoS class of the radio bearer is identified by the QoS profile of the corresponding SAE bearer signaled from the serving gateway to the eNB as described above. The operator can assign a specific amount of his total cell capacity to the total traffic associated with a radio bearer of a specific QoS class. The main purpose of adopting this method based on class is to make it possible to distinguish the processing of packets according to the QoS class to which they belong.

[Structure of (broadcast) system information]
In 3GPP terminology, (broadcast) system information is also referred to as BCCH information, ie the broadcast control channel (logical channel) of the radio cell to which the UE is connected (active state) or attached (idle state) Means information transmitted in

  The system information generally includes a master information block (MIB: Master Information Block) and several system information blocks (SIBs). The master information block (MIB) contains control information on each system information block. Control information associated with each system information block (SIB) may have the following structure. That is, each control information associated with the SIB can indicate the position of the SIB relative to a common timing reference on the transport channel on which the SIB is transmitted (eg, time-frequency plane for OFDM radio access Position, ie, a specific resource block allocated for transmission of each SIB). Furthermore, the repetition period of SIB can be indicated. This repetition period indicates the period in which each SIB is transmitted. Furthermore, the control information may also include the timer value of the timer based update mechanism of the SIB information, or the value tag in case of tag based update of the SIB information.

  The following table is an overview of the classifications and types of system information blocks (SIBs) in the UMTS legacy system, as defined in Section 8.1.1 of Non-Patent Document 4 (incorporated herein by reference). Is shown. System information is also defined in the LTE system, and details are described in section 6.3.1 of Non-Patent Document 5 (incorporated herein by reference).

Device to Device (D2D) communication technology will be implemented in LTE Release 12, as described in more detail in a later section. Currently, in the standardization work by 3GPP, in particular, the definition of the system information block type 18 (SIB type 18: SystemInformationBlock Type 18) is advanced to include some information related to ProSe direct communication and direct discovery. The following definition of SIB 18 is an excerpt from the currently considered currently-considered change request r2-143565, which was previously agreed on ProSe for non-patent document 3. However, this is not a final decision but should be understood as an example only.

  As is apparent from the above system information, the commIdleTxPool field (including the commSA-TxResourcePoolCommon sub-field) indicates a common resource, and UEs that have received SIB 18 and are still in an idle state Resources) can be used on a base basis). In other words, the network operator can commonly define radio resources for all UEs, but these radio resources are only available when the UEs are still idle. As described later, these radio resources defined by commIdleTxPool are classified as mode 2 resources (used autonomously by the UE).

Buffer status report
The buffer status reporting procedure is used to provide the serving eNB with information regarding the amount of data ready for transmission in the UE's uplink buffer. The RRC layer sets up two timers periodicBSR-Timer and retxBSR-Timer, and optionally, buffer status report (BSR) by signaling logicalChannelGroup for each logical channel, which assigns logical channels to logical channel groups (LCGs) Control. Further details regarding buffer status reporting are described in section 5.4.5 of Non-Patent Document 6 (incorporated herein by reference).

[LTE inter-device (D2D) proximity service (ProSe)]
Proximity based applications and services are a new trend in social technology. Areas to be identified include commercial services of interest to businesses and users and services related to public safety. By introducing the Proximity Service (ProSe) feature into LTE, the 3GPP industry can serve this growing market while at the same time the urgency of several public safety communities that use LTE in tandem Meet the needs of

  Device-to-device (D2D) communication is a technology element in LTE release 12. Device-to-device (D2D) communication techniques can increase spectral efficiency in D2D as an underlay for cellular networks. For example, if the cellular network is LTE, then all physical channels carrying data use SC-FDMA in D2D signaling.

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

  In D2D communication, UEs transmit data signals to each other over a direct link using cellular resources without going through a base station (BS). D2D users communicate directly but remain under control of the base station (at least when in coverage of the eNB). Thus, with D2D, system performance 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 (in the case of TDD, except in the case of out of coverage) of the cell providing the coverage. Furthermore, D2D transmission / reception does not use full duplex on a given carrier. From the point of view of the individual user equipments, do not use full duplex with D2D signal reception and LTE uplink transmission on a given carrier (ie D2D signal reception and LTE uplink transmission can not occur simultaneously).

  In D2D communication, when one specific UE 1 is in a transmission role (sending user equipment or transmitting terminal), UE 1 transmits data, and another UE 2 (receiving user equipment) receives it. UE1 and UE2 can exchange transmission and reception roles. The transmission from UE1 may be received by one or more UEs similar to UE2.

The contents of the agreement related to D2D communication regarding the user plane protocol are shown below (see also Section 9.2.2 of Non-Patent Document 7 (also incorporated herein by reference)).
-PDCP:
1: MD2D broadcast communication data (ie IP packets) should be treated as normal user plane data.
1: 1: For MD2D broadcast communication data, header compression / decompression in PDCP can be applied.
-For public safety related D2D broadcast operation, use U mode for header compression in PDCP.
-RLC:
1: 1: Use RLC UM for MD2D broadcast communication.
Segmentation and Reassembly are supported in L2 by RLC UM.
The receiving user equipment needs to maintain at least one RLC UM entity per sending peer user equipment.
There is no need to configure the RLC UM entity of the receiver before receiving the first RLC UM data unit.
At present, the need for RLC AM or RLC TM in D2D communication for transmitting user plane data is not recognized.
-MAC:
1: 1: Do not assume HARQ feedback in MD2D broadcast communication.
The receiving user equipment needs to recognize the source ID in order to identify the RLC UM entity of the receiver.
The MAC header contains an L2 destination ID that enables packet filtering in the MAC layer.
The L2 destination ID can be a broadcast address, a group cast address, or a unicast address.
L2 Groupcast / Unicast: The L2 destination ID conveyed in the MAC header makes it possible to discard received RLC UM PDUs, even before passing them to the RLC entity of the receiver.
• L2 broadcast: The receiving user equipment processes all RLC PDUs received from all transmitters and reassembles and passes IP packets to upper layers.
MAC subheader contains logical channel ID (LCID) (to distinguish multiple logical channels).
For D2D, at least multiplexing / demultiplexing, priority handling, and padding are useful.

[Radio resource allocation]
From the transmitting UE's point of view, UEs that support proximity services (ProSe enabled UEs) can operate in the following two modes of resource allocation.

  Mode 1 refers to a scheme in which the eNB schedules resource allocation, in which case the UE requests a transmission resource from the eNB (or a Release 10 relay node), and receives it to relay the eNB (or the Release 10) Nodes) schedule the correct resources that the user equipment will use to transmit "direct" data and "direct" control information (e.g. Scheduling Assignment (SA)). The UE needs to be in the RRC_CONNECTED state to transmit data. Specifically, the UE sends a scheduling request (dedicated scheduling request (D-SR) or random access) to the eNB, and then sends a buffer state report (BSR: Buffer State Report) in the normal manner (next section “D2D communication (See also "Transmission procedure in Based on the buffer status report (BSR), the eNB can determine that the user equipment has data to be transmitted by ProSe direct communication, and can estimate resources required for transmission.

On the other hand, mode 2 means that the UE autonomously selects a resource, in which case the resource (time and frequency) for transmitting "direct" data and "direct" control information Is selected from the resource pool on its own. One resource pool is defined (eg by the commIdleTxPool field), eg, by the contents of SIB 18 (described in the previous section), this particular resource pool is broadcast in the cell and everything in the cell is still in the RRC_IDLE state. Common to all UEs. Alternatively or additionally, the eNB may define another resource pool to signal for a particular UE (ie, by using the commTxResourcePool field). Although not finally determined yet, standardization is currently in progress with respect to the corresponding ProSe information element according to the change request r2-143565 for Non-Patent Document 3. Thus, the following definitions should be understood as examples only.

  This ProSeCommConfig information element may be part of the network response sent by the eNB in response to a corresponding request by the UE attempting to perform D2D communication. For example, as shown in FIG. 16, when the UE desires to perform D2D communication, it may transmit a D2D Communication Interest Indication to the eNB. In this case, the D2D communication response (eg, as part of RRC Communication Reconfiguration) may include the ProseCommConfig information element described above.

  Furthermore, pre-configured radio resources that can be utilized for scheduling assignment (SA) or D2D communication of data UEs that are out of coverage of the cell of the eNB can also be classified as resources in mode 2 .

  Which resource allocation mode the UE uses is configurable by the eNB as described above. Furthermore, which resource allocation mode the UE uses for D2D data communication may also be determined by the RRC state (ie, RRC_IDLE or RRC_CONNECTED) and the UE's coverage state (ie, within or out of coverage). it can. If the UE has a serving cell (ie, the UE is in the RRC_CONNECTED state or is camped on a particular cell in the RRC_IDLE state), the UE is considered to be in coverage.

According to the current agreement in 3GPP (see Change Request to Non-Patent Document 8 in R2-143672 (see section on resource allocation)), the following rules for resource allocation mode apply to the UE.
If the UE is out of coverage, it can only use mode 2.
If the UE is in coverage, it can use mode 1 if it is configured by the eNB to be able to use mode 1
If the UE is in coverage, it can use mode 2 if it is configured by the eNB to enable mode 2.
The UE can change from mode 1 to mode 2 or from mode 2 to mode 1 only if the UE is configured by the eNB to change mode when no exception condition exists. If the UE is in coverage, the UE uses only 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 permitted to use mode 2, even though it is set to use mode 1.

  While the user equipment is in the coverage area of the E-UTRA cell, it performs ProSe direct communication transmission on the uplink carrier only on the resources allocated by that cell (even if the resource of the carrier is eg UICC (generic IC card) : Even if it is preset in Universal Integrated Circuit Card)).

For UEs in the RRC_IDLE state, the eNB may select one of the following options:
-The eNB provides mode 2 transmission resource pool in SIB (System Information Block). UEs that are authorized for ProSe direct communication use these resources for ProSe direct communication in the RRC_IDLE state.
-ENB indicates in SIB that it supports D2D but does not provide resources for ProSe direct communication. The UE needs to enter the RRC_CONNECTED state to perform ProSe direct communication transmission.
For UEs in the RRC_CONNECTED state, the following may be done.
-When the UE in the RRC_CONNECTED state and permitted to perform ProSe direct communication transmission needs to perform ProSe direct communication transmission, it indicates to the eNB that it desires to perform the ProSe direct communication transmission.
-The eNB confirms whether the UE in the RRC_CONNECTED state is permitted to transmit ProSe direct communication, using the UE context received from the MME.
-For the UE in the RRC_CONNECTED state, the eNB can set up, using dedicated signaling, a transmission resource pool of a mode 2 resource assignment scheme that can be used without restriction while the UE is in the RRC_CONNECTED state. Instead of this, the eNB may set the transmission resource pool of the mode 2 resource allocation scheme that can be used by the UE in an exceptional case to the UE in the RRC_CONNECTED state by dedicated signaling. Yes, and in exceptional cases, the UE follows mode 1.

  The above behavior of the UE for resource allocation is simplified as a state diagram in FIG. 7 and FIG. FIG. 7 shows the case where the UE is in the RRC_IDLE state, which distinguishes between in-coverage and out-of-coverage. It should be noted that UEs that are out of coverage and in RRC IDLE state can use mode 2 resource allocation. Currently, no exceptional cases are defined for UEs in the RRC_IDLE state. On the other hand, FIG. 8 shows the case where the UE is in the RRC_CONNECTED state, and distinguishes between in-coverage and exceptional cases. As apparent from the figure, UEs in connected state and exceptional cases can use mode 2 resource allocation.

  FIG. 9 illustrates the use of transmit / receive resources in overlay (LTE) and underlay (D2D) systems.

  Basically, the eNodeB controls whether the UE applies mode 1 transmission or mode 2 transmission. When the UE recognizes resources that can transmit (or receive) D2D communication, the current state of the art uses corresponding resources only for corresponding transmission / reception. For example, in FIG. 9, D2D subframes are used only for the purpose of receiving or transmitting D2D signals. Because the UE as a D2D device operates in half duplex mode, it can either receive or transmit D2D signals at any time. Similarly, the other subframes shown in FIG. 9 can be used for LTE (overlay) transmission and / or reception.

[Transmission procedure in D2D communication]
The transmission procedure of D2D data differs depending on the resource allocation mode. As described above, in mode 1, the eNB explicitly schedules resources for carrying scheduling assignment (SA) and D2D data after the corresponding request from the UE. Specifically, the eNB can notify the UE that D2D communication is basically permitted but mode 2 resources (i.e. resource pool) are not provided. This notification may be performed, for example, by exchanging the D2D communication interest notification by the UE with the corresponding response D2D communication response as shown in FIG. 16, in which case the corresponding example described above The information element of ProseCommConfig does not include commTxREsourcePool, that is, the UE desiring to initiate direct communication including transmission must request resource allocation from E-UTRAN for each individual transmission. Therefore, in such a case, the UE has to request the resources of each individual transmission, and the following shows an example of a series of steps of request / assignment procedure for this mode 1 resource assignment.
Step 1 UE sends SR (scheduling request) to the eNB via PUCCH.
Step 2 The eNB grants uplink resources (for the UE to send a buffer status report (BSR)) via PDCCH scrambled by C-RNTI.
Step 3 The UE sends a D2D BSR over PUSCH indicating the status of the buffer.
Step 4 The eNB allocates D2D resources (for the UE to send data) via PDCCH scrambled by D2D-RNTI.
Step 5 The D2D sender UE sends scheduling assignment (SA) / D2D data according to the grant received in step 4.

Scheduling Assignment (SA) is a compact (low payload) message that includes control information (e.g., a pointer pointing to a time-frequency resource for transmitting the corresponding D2D data). The contents of the scheduling assignment (SA) basically follow the grant received in step 4 above. Although the details of the contents of the D2D grant and scheduling assignment (SA) have not been determined at present, the following agreement has been made as specific assumptions regarding the contents of the scheduling assignment (SA).
• Frequency resources are indicated by Release 8 uplink type 0 resource allocation (5 to 13 bits depending on system bandwidth)
• 1-bit frequency hopping indicator (per release 8)
Some reinterpretation of indexing is to be defined so that physical resource blocks (PRBs) outside of the resource pool configured in mode 2 are not used by hopping.
-Only single cluster resource allocation is effective. That is, if there is a gap in the resource pool in the frequency domain, resource allocation does not span the gap.
• RV index is not used in scheduling assignment (SA). The RV pattern of the data is {0, 2, 3, 1}.

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

  FIG. 10 exemplarily shows the transmission of scheduling assignment (SA) and D2D data for two UEs (UE-A and UE-B). The resources for sending the scheduling assignment (SA) are periodic, and the resources used for transmission of D2D data are indicated by the corresponding scheduling assignment (SA).

Resource Pool for Scheduling Allocation (SA) and D2D Data
The scheduling allocation (SA) when the UE is out of coverage and the resource pool for D2D data can be configured as follows.
The resource pool used to receive the scheduling assignment (SA) is pre-configured.
-The resource pool used for the transmission of scheduling assignments (SA) is pre-configured.
The resource pool used to receive D2D data is pre-configured.
The resource pool used for the transmission of D2D data is preset.

The resource pool for scheduling assignment (SA) when the UE is in coverage may be configured as follows.
The resource pool used to receive the scheduling assignment (SA) is configured by the eNB via dedicated RRC or broadcast signaling.
-The resource pool used for transmission of scheduling assignment (SA) is configured by the eNB via RRC when mode 2 resource assignment is used.
The resource pool used for the transmission of scheduling assignments (SAs) is not known to the UE when mode 1 resource assignment is used.
-If mode 1 resource assignment is used, the eNB will schedule specific resources to use for transmission of scheduling assignment (SA). The particular resources allocated by the eNB are within the resource pool for scheduling assignment (SA) reception provided to the UE.

[UE coverage status in D2D]
As already mentioned above (see, eg, FIG. 7 and FIG. 8), the resource allocation method in D2D communication also depends on the UE's coverage state (ie, in-coverage and out-of-coverage) in addition to the RRC state (ie, RRC_IDLE and RRC_CONNECTED) Do. If the UE has a serving cell (ie, the UE is in the RRC_CONNECTED state or is camped on a particular 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 distinguished into sub-states for D2D. FIG. 11 shows four different states that can be associated with the D2D UE, 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. Furthermore, the network sets whether UE1 should use resource allocation mode 1 or resource allocation mode 2.
-State 2: UE2 has downlink coverage but no uplink coverage (i.e. only downlink coverage). The network broadcasts (contention based) resource pools. In this state, the transmitting UE selects the resources to be used for scheduling assignment (SA) and data from the resource pool configured by the network. In this state, only resource allocation in mode 2 is possible for D2D communication.
State 3: UE3 is already considered out of coverage (OOC), strictly speaking, as it has no uplink and downlink coverage. However, UE 3 is within the coverage of several UEs (eg, UE 1) that are themselves within the coverage of the cell, ie, these UEs may also be referred to as CP relay UEs, and the UEs in state 3 in FIG. The area of can be referred to as the 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, this information is sent by the eNB (SIB) and the state 3 coverage via PD2DSCH by the CP UE relay UE in the coverage of the cell It is forwarded to the outside (OOC) UE. A network controlled (contention based) resource pool is signaled by the PD2 DSCH.
-State 4: UE4 is out of coverage and does not receive PD2DSCH from another UE in the coverage of the cell. 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 pool of resources configured in advance.

  The reason for distinguishing between state 3 out of coverage (OOC) and state 4 out of coverage (OOC) is primarily to avoid possible strong interference between D2D transmissions from devices out of coverage and legacy E-UTRA transmissions. In order to Generally, D2D capable UEs have pre-configured resource pools for transmission of D2D SAs and data to use when out of coverage. When these out-of-coverage UEs transmit near their cell boundaries using these pre-configured resource pools, the interference between their D2D transmissions and legacy transmissions in the coverage will be in-cell communication. Can have an adverse effect on If the D2D capable UEs in the coverage transfer the D2D resource pool configuration to devices outside these coverage near the cell boundary, then the UEs out of coverage will transmit their transmissions to those resources specified by the eNodeB. It can be limited, thus minimizing interference with legacy transmissions in coverage. Therefore, RAN1 introduced a mechanism in which UEs in the coverage transfer resource pool information and other settings related to D2D to a device (UE in state 3) just outside the coverage area.

  The physical D2D synchronization channel (PD2DSCH) is used for the purpose of conveying this information about the in-coverage D2D resource pool to UEs located in the vicinity in the network, and thus the resource pool in the vicinity of the network is adjusted. The final content of PD2DSCH has not been finalized yet.

[D2D discovery]
ProSe (Proximity Service) Direct Discovery (ProSe Direct Discovery) allows ProSe-enabled user equipment to transmit E-UTRA direct radio signals via another PC5 interface to another ProSe-compatible user equipment or devices in the vicinity. It is defined as the procedure used to discover using. FIG. 12 schematically illustrates the PC5 interface for direct discovery between devices.

  The upper layer handles discovery information announcement and monitoring permissions. For this purpose, the user equipment has to exchange pre-defined signals (referred to as discovery signals). The user equipment maintains a list of nearby user equipment by periodically checking the discovery signal in order to establish a communication link when needed. The discovery signal needs to be detected with high reliability even in an environment where the signal to noise ratio (SNR) is low. It is necessary to allocate resources for the discovery signal so that the discovery signal can be transmitted periodically.

  There are two types of ProSe direct discovery: open and restricted. The open type is where there is no need for explicit permission from the user equipment to be discovered, and limited type discovery is only done with explicit permission from the user equipment to be found.

  ProSe Direct Discovery can be a stand-alone service enabler at the discovering user equipment, which is the user equipment at which the discovering user equipment is found in the particular application Allows you to use information from The information transmitted in ProSe direct discovery may be, for example, “find taxi near”, “find coffee shop”, “find nearest police station”, etc. The user equipment on the discovering side can acquire necessary information through ProSe direct discovery. In addition, depending on the information obtained, ProSe Direct Discovery can be used to perform subsequent operations in the telecommunication system (eg, initiate ProSe Direct Communication, etc.).

[ProSe Direct Discovery Model]
ProSe Direct Discovery is based on several discovery models. The outline is shown below. The model for ProSe direct discovery is defined in more detail in section 5.3 of Non-Patent Document 9 (incorporated herein by reference).

Model A ("I am here")
Model A is also expressed as "I am here." Because the announcer's user equipment broadcasts information about itself (identification information of its own ProSe application, identification information of ProSe UE, etc.) in the discovery message, thereby revealing its own identity and being available to itself. To communicate to other devices of the communication system.

  According to model A, two roles of ProSe enabled user equipment involved in ProSe direct discovery are defined. The ProSe compliant user equipment can have the functions of the user equipment that announces and the user equipment that monitors. The announcer's user equipment announces specific information that can be used by nearby user equipment that has the discovery permission. The monitoring user equipment monitors specific information of interest in the vicinity of the announcer user equipment.

  In this model A, the announcing user equipment broadcasts discovery messages at pre-defined discovery intervals, and the monitoring user equipment interested in these messages read and process the messages.

Model B ("Who is there?" / "Are you there?")
This model defines the following two roles of ProSe enabled UEs involved in ProSe direct discovery.
-Discovering UE: This UE sends a request that contains specific information about what it wants to discover.
-Discovered UE: The UE that has received the request message can respond with some information related to the discovering UE's request.

  Model B is equivalent to "Who is there? / Are you there?" This is because the discovering user equipment transmits information on another user equipment for which it wants to receive a response. The information to be transmitted may be, for example, information on a ProSe application ID corresponding to a group. Members of the group can respond to this transmitted information.

  According to this model B, two roles of ProSe-enabled user equipment involved in ProSe direct discovery are defined: user equipment on the discovery side and user equipment on the discovery side. The discovering user equipment sends a request containing specific information about what it wants to discover. On the other hand, the discovered user equipment receiving this request message can respond with some information related to the request of the discovering user equipment.

  The content of the discovery information is transparent to the access layer (AS), and the access layer (AS) does not recognize the content of the discovery information. Thus, the access layer does not distinguish between the various models of ProSe direct discovery, nor the type of ProSe direct discovery. The ProSe protocol passes only valid discovery information to announce to the access layer (AS).

  The user equipment may be involved in the announcement and monitoring of discovery information in both RRC_IDLE and RRC_CONNECTED states according to the eNB configuration. The user equipment announces and monitors discovery information subject to half-duplex constraints.

[Type of discovery]
FIG. 13 is a diagram showing an IDLE mode and a CONNECTED mode when receiving a discovery resource in D2D communication, in relation to a resource allocation procedure.

  D2D communication is controlled by the network (in this case the carrier manages the switch between direct transmission (D2D) and the conventional cellular link) or the device directly links without the control of the carrier It can be managed by In D2D, infrastructure mode and ad hoc communication can be combined.

  In general, device discovery is necessary periodically. Furthermore, the D2D device performs device discovery using a discovery message signaling protocol. For example, a D2D capable user equipment can send its own discovery message, and another D2D capable user equipment can receive this discovery message and use this information to establish a communication link. As an advantage of the hybrid network, if the D2D device is also within the communication range of the network infrastructure, a network entity such as an eNB may additionally support the transmission and configuration of discovery messages. Coordination / control of transmission and configuration of discovery messages by the eNB is also important to prevent interference between D2D messaging and cellular traffic controlled by the eNB. Furthermore, devices within the coverage can support the ad hoc discovery protocol, even if some of the devices are outside the scope of network coverage.

At least the following two types of discovery procedures have been defined in order to define the terminology used further in the description.
Type 1: A resource allocation procedure in which resources for announcing discovery information are allocated without targeting specific user equipment, and further characterized by:
O The eNB provides the user equipment with the configuration of the resource pool used to announce the discovery information. Configuration can be signaled in SIB.
O The user equipment autonomously selects the radio resource (s) from the indicated resource pool and announces the discovery information.
O The user equipment can announce discovery information on randomly selected discovery resources during each discovery period.
Type 2: A resource allocation procedure in which resources for announcing discovery information are allocated for a specific user equipment and further characterized:
O The user equipment in RRC_CONNECTED mode may request resources from the eNB to announce the discovery information via RRC. The eNB allocates resources via RRC.
○ Resources are allocated within the resource pool set for the user equipment to be monitored.

  According to the type 2 procedure, resources are allocated, for example, semi-persistent for transmission of discovery signals.

If the user equipment is in RRC_IDLE mode, the eNB may select one of the following options.
-The eNB may provide type 1 resource pool in SIB to announce discovery information. User equipment that is authorized for ProSe Direct Discovery announces discovery information using these resources in RRC_IDLE mode.
-The eNB can indicate in SIB that it supports D2D but does not provide resources to announce discovery information. The user equipment needs to enter RRC_CONNECTED mode to request D2D resources to announce discovery information.

  For user equipment in the RRC_CONNECTED state, the user equipment that is authorized to perform the ProSe Direct Discovery Announcement informs the eNB that it wants to perform the D2D Discovery Announcement. Then, the eNB confirms whether the user equipment is permitted to announce ProSe Direct Discovery using the UE context received from the MME. The eNB may configure the user equipment via dedicated RRC signaling (or no resources) to use type 1 resource pool or type 2 dedicated resources for announcement of discovery information. The resources allocated by the eNB are valid until: a) the eNB de-configures the resource by RRC signaling, or b) the user equipment enters the IDLE mode.

  The receiving user equipment in RRC_IDLE mode and RRC_CONNECTED mode monitors both the type 1 and type 2 discovery resource pools that are allowed. The eNB provides the configuration of the resource pool used to monitor the discovery information in SIBs. The SIB may also include discovery resources used to announce in neighboring cells.

Wireless Protocol Architecture
FIG. 14 schematically shows a radio protocol stack (AS: Access Stratum) for ProSe direct discovery.

  The AS layer functions as an interface with the upper layer (ProSe protocol). Thus, the MAC layer receives discovery information from the upper layer (ProSe protocol). In this case, the IP layer is not used to transmit discovery information. Furthermore, the AS layer has a scheduling function, and the MAC layer determines radio resources to be used to announce discovery information received from higher layers according to this scheduling function. In addition to this, the AS layer has the function of generating discovery PDUs, and according to this function, the MAC layer constructs a MAC PDU carrying discovery information and physically transmits the MAC PDU on the determined radio resource. Pass to layer MAC header is not added.

  At the user equipment, the RRC protocol informs the MAC layer of the discovery resource pool. Furthermore, the RRC informs the MAC layer of the type 2 resources assigned for transmission. There is no need for a MAC header. The MAC header for discovery does not include fields based on when performing filtering in L2. Filtering discovery messages at the MAC level is not considered to save processing power or power compared to performing filtering based on ProSe UE ID or ProSe application ID in the upper layer. The receiving MAC layer passes all received discovery messages to the upper layer. At this time, the MAC layer passes only the correctly received message to the upper layer.

  In the following, it is assumed that L1 (PHY) indicates to the MAC layer whether the discovery message is correctly received. Furthermore, it is assumed that the upper layer always passes only valid discovery information to the AS layer.

[D2D synchronization]
The main role of synchronization is to allow the receiver to obtain time and frequency references. Such criteria can be used for at least the following two purposes. 1) Align receive window and frequency correction when detecting D2D channel, 2) align transmitter timing and parameters when transmitting D2D channel. The following channels are currently defined in 3GPP for the purpose of synchronization.
-D2DSS D2D synchronization signal-PD2DSCH physical D2D synchronization channel-PD2 DSS primary D2D synchronization signal-SD2 DSS secondary D2D synchronization signal

Furthermore, in 3GPP, the following terminology relating to synchronization is agreed upon, and these terminology will be exemplarily used in the remainder of the present application.
D2D Sync Source: A node that transmits at least a D2D sync signal. The D2D synchronization source may basically be eNB or D2D UE.
D2D synchronization signal: a signal from which the UE can obtain timing and frequency synchronization.

  D2D synchronization can be understood as a procedure similar to LTE cell search. The following synchronization procedures for receivers and transmitters are currently being considered in 3GPP in order to enable both network control and efficient synchronization in partial and in-coverage scenarios.

[Receiver synchronization]
The ProSe-enabled UE periodically searches for an LTE cell (following the mobility procedure of LTE) and the D2DSS / PD2DSCH transmitted by a Synchronization Source (SS) UE.

  When a suitable cell is found, the UE camps on that cell and follows cell synchronization (according to the LTE legacy procedure).

  When the appropriate D2DSS / PD2DSCH to be sent by the SS (synchronization source) UE is found, the UE synchronizes its receiver with all incoming D2DSS / PD2DSCH (depending on the UE's capabilities) and the incoming connection ( Monitor them for scheduling assignments). It should be noted that the D2DSS transmitted by the eNodeB D2D synchronization source is a Release 8 PSS / SSS (Primary Synchronization Signal / Secondary Synchronization Signal). The eNodeB D2D synchronization source has higher priority than the UE D2D synchronization source.

Synchronize transmitters
The ProSe-enabled UE periodically searches for an LTE cell (following the mobility procedure of LTE) and the D2DSS / PD2DSCH transmitted by the SS (synchronization source) UE.

  When an appropriate cell is found, the UE camps on that cell and follows cell synchronization to be able to transmit D2D signals. In such case, the network may configure the UE to transmit D2 DSS / PD2 DSCH according to cell synchronization.

  If no suitable cell is found, the UE checks if any of the incoming D2 DSS / PD2 DSCH can be further relayed (ie the maximum hop count has not been reached), and (a) can be further relayed the incoming D2 DSS / If PD2DSCH is found, then the UE synchronizes its transmitter with its signal and sends D2DSS / PD2DSCH accordingly, or (b) UE can not find an incoming D2DSS / PD2DSCH that can be further relayed Operates as an independent synchronization source, and transmits D2 DSS / PD2 DSCH according to any internal synchronization reference.

  Further details of the synchronization procedure in D2D are described in Section 7 of Non-Patent Document 9 (incorporated herein by reference).

[Cell Selection and RRC Connection Establishment]
FIG. 15 schematically and exemplarily shows prior art message exchange between a UE and an eNB for selecting a cell and establishing an RRC connection. The selection of cells in step 2 is based on, for example, section 5.2.3 of Non-Patent Document 11 (incorporated herein by reference). UEs not camped on WAN (Wide Area Network, eg LTE) cells are considered as out of coverage (OOC). Camp-on to a cell can be based on the cell selection criteria / process defined in Section 5.2.3 of Non-Patent Document 11. Thus, before completing step 2, the UE is generally considered out of coverage (OOC). If cell selection is successful and the UE camps on (in the appropriate or allowed cell), the UE is in RRC idle state. The UE remains in RRC idle state until step 7 (ie, until it receives an RRCConnectionSetup message from the network) and then changes to RRC connected state.

3GPP TS 36.211, "Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation (Release 8)" TS 36.304 3GPP TS 36.331 3GPP TS 25.331, "Radio Resource Control (RRC)", version 12.2.0 TS 36.331 v12.2.0 3GPP TS 36.321 3GPP TS 36.843 vers. 12.0.0 TS 36.300 3GPP TS 23.303 V12.1.0 TS 36.843 V12.0.1 3GPP TS 36.304 v12.1.0

  An exemplary embodiment which does not limit the present invention is a method of allocating radio resources to a transmitting terminal for performing direct communication transmission over a direct link connection, which improves the above mentioned problems. To provide a way. The independent claims provide an exemplary embodiment that is not limiting the present invention. Advantageous embodiments are the subject matter of the dependent claims.

  According to a first aspect, an additional (temporary transmission for performing direct communication transmission) is added to an idle transmission radio resource pool already defined in the latest technology. Network resource for the transmission radio resource pool. The state of the art radio resource pool for idle state transmission is limited to terminals in idle state, but the additional radio resource pool for transmission according to the first aspect is independent of the idle state or connection state of the terminal Is set such that the length of time that this temporary transmission radio resource pool can be used by the transmitting terminal is limited. Thus, the base station broadcasts in its cell system information including information on this temporary transmission radio resource pool and the corresponding configuration information. The temporary transmission radio resource pool according to the first aspect is the same as the state-of-the-art idle state transmission radio resource pool, the transmitting terminal that has received the system information broadcast can directly access the receiving terminal through the direct link connection. 3 illustrates radio resources available to perform direct communication transmission.

  Various implementations of this first aspect differ as to how this additional resource pool usage time is limited by the configuration information, or the terminal uses such resources of the temporary transmission radio resource pool Sometimes the terminal includes the further requirement that it must establish a wireless connection with the base station (at least try to establish it).

  By using this additional resource pool, it is possible to prevent interruptions while the terminals in the cell establish a wireless connection with the base station.

  Thus, in one general aspect, the techniques disclosed herein allocate to a transmitting terminal radio resources for performing direct communication transmission to a receiving terminal over a direct link connection in a communication system. To provide a way. The method comprises the following steps performed by the transmitting terminal: receiving the system information broadcast from the base station, wherein the system information broadcast is directly linked by the transmitting terminal receiving the system information broadcast. Information about the temporary transmission radio resource pool indicating the radio resources available for performing direct communication transmission to the reception side terminal through the frame, and the temporary transmission radio resource pool available by the transmission side terminal And D. limiting a certain length of time, including information on configuration information on a temporary transmission radio resource pool. Also provided are corresponding terminals and base stations involved in the method.

  According to a second aspect, a preconfigured transmission radio resource pool is made available to terminals within the coverage of a cell of a base station. Although such a preset radio resource pool for transmission is already known in the state of the art for use in out-of-coverage situations, in a second aspect, the terminal covers the use of this resource pool It extends to situations that are within. In this context, "pre-configured" may be pre-selected, for example by information in the USIM card of the mobile phone, or by upper layer signaling from the core network, even without receiving any system information from the radio access. It should be understood that the configured radio resource pool for transmission is known to the terminal.

  Similar to the first aspect, various implementations of the second aspect may be used by such a preconfigured radio resource pool for transmission when the terminal is within the coverage of the cell. This limitation can be implemented in a variety of ways, including an option to limit the amount of time that is possible. In another implementation of the second aspect, when the terminal uses such resources of the preset radio resource pool for transmission, as a prerequisite, the terminal has to establish a wireless connection with the base station. You must (at least try to establish).

  Thus, in one general aspect, the technology disclosed herein provides a transmitting terminal that performs direct communication transmission to a receiving terminal over a direct link connection in a communication system. The transmitting terminal is preset with a transmitting radio resource pool indicating radio resources available to the transmitting terminal for performing direct communication transmission to the receiving terminal through direct link connection. The radio resource pool for transmission set in advance is available when the transmitting terminal is within the coverage of the base station's cell.

  Further benefits and advantages of the disclosed embodiments will become apparent from the present specification and the drawings. These benefits and advantages may be separately provided by the various embodiments and features disclosed in the specification and drawings, and it is not necessary to have all of them to obtain one or more of these benefits and advantages. .

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

  In the following, exemplary embodiments will be described in more detail with reference to the attached drawings.

1 illustrates an exemplary architecture of a 3GPP LTE system. Fig. 3 shows an exemplary overview of the entire 3 GPP LTE E-UTRAN architecture. Fig. 6 shows an exemplary subframe boundary of downlink component carriers defined for 3GPP LTE (Release 8/9). Fig. 6 shows an exemplary downlink resource grid of downlink slots defined in 3GPP LTE (Release 8/9). The L2 layer structure of 3GPP LTE-A (release 10) in the state where the carrier aggregation of the downlink is enabled is shown. The L2 structure of 3GPP LTE-A (release 10) in the state where the carrier aggregation of the uplink is enabled is shown. It shows an outline of resource allocation modes available to the terminal when in the RRC_IDLE state, in the coverage of the cell, and out of the coverage of the cell, and transitions between the resource allocation modes. It shows a summary of resource allocation modes available to the terminal when in the RRC_CONNECTED state, within cell coverage, and outside cell coverage, and transitions between those resource allocation modes. Fig. 6 illustrates the use of transmit / receive resources in an overlay (LTE) and underlay (D2D) system. Figure 3 shows the transmission of scheduling assignment (SA) and D2D data for two UEs. The coverage associated with four different states that can be associated with D2D UEs is shown. Fig. 5 schematically illustrates a PC5 interface for direct discovery between devices. The diagram which showed idle mode and connection mode at the time of receiving a resource for discovery in D2D communication is shown. Fig. 3 schematically shows a radio protocol stack for ProSe direct discovery. Fig. 2 illustrates an exemplary prior art message exchange between a UE and an eNodeB to select a cell and establish an RRC connection. Fig. 7 illustrates the exchange of D2D communication interest notification messages and corresponding D2D communication responses. Fig. 6 shows an exemplary movement of the UE at the edge of the cell. FIG. 16 is an extension of FIG. 15 and exemplarily shows a message exchange in the prior art for selecting a cell and establishing an RRC connection, wherein UE-A shows an interest in D2D communication and for transmission of D2D communication Request dedicated radio resources for Furthermore, various different time periods are shown. It shows a message exchange if the RRC connection establishment procedure fails. It indicates a period in which the UE can not transmit D2D communication. FIG. 10 shows how the UE applies the T-RPT pattern to subframes for mode 1 resources. Fig. 6 illustrates how the UE applies T-RPT pattern to subframes for mode 2 resources.

  The following embodiments may be advantageously utilized in mobile communication systems such as, for example, 3GPP LTE-A (release 10/11/12) described in the background section, but these embodiments It should be noted that the present invention is not limited to use in the exemplary communication network.

  Mobile stations or mobile nodes or user terminals are physical entities in a communication network. One node can have several functional entities. A functional entity means a software module or hardware module that performs a predetermined set of functions or provides a predetermined set of functions to a node or another functional entity of a network, or both. A node can have one or more interfaces that attach itself to a communication device or medium, and the nodes can communicate through these interfaces. Similarly, a network entity can have a logical interface that attaches a functional entity to a communication device or medium, and the network entity can communicate with another functional entity or correspondent node through the logical interface.

  As used in the claims and in this application, "sender terminal" means a user terminal in the role of transmitter. Conversely, "receiving side terminal" means a user terminal in the role of a receiver. The adjectives "sender" and "receiver" are only intended to clarify temporal behavior / roles.

  “Direct communication transmission” as used in the claims and in the present application means, as an example, device-to-device (D2D) communication currently being considered in LTE release 12. Correspondingly, the term "direct link connection" is, as an example, a connection channel or communication channel through a PC5 interface that directly connects two D2D user terminals, and the direct transmission of data without network involvement. It means a connection channel or communication channel that enables exchange. In other words, the communication channel is established in the communication system, bypassing the eNodeB (base station), between two user equipment close enough to exchange data directly.

  The terms "wireless connection establishment procedure" as used in the claims and in the present application can be understood as procedures involving random access procedures or procedures without. Thus, initiating a wireless connection establishment procedure can be understood as equivalent to transmitting a preamble of a random access procedure or as equivalent to transmitting an RRC connection request message . Thus, in the context of 3GPP LTE, the radio connection establishment procedure may be a random access procedure followed by an RRC connection establishment procedure.

  The term "dedicated radio resource" as used in the claims and in the present application is to be understood as a radio resource explicitly assigned to a particular terminal by a base station (eNodeB). The dedicated radio resources may themselves be either mode 1 resources or mode 2 resources as described in the background section. This term is to be understood as contrasting with "common radio resources" which can be commonly used by terminals in a cell. For example, a radio resource pool for transmission defined by system information (e.g. SIB 18) is broadcast in the cell, so this radio resource can be used by the terminal receiving this system information.

  The expression "initiates the wireless connection establishment procedure" and similar expressions shall be understood as requiring the terminal to attempt to establish a wireless connection with the base station, but the wireless connection establishment procedure fails. Note that it may be. In other words, although the terminal is required to try to establish the wireless connection, the terminal succeeds only in starting the corresponding wireless connection establishment procedure, and continues the wireless connection establishment procedure as it is and successfully completes the wireless connection. It does not have to succeed in establishing. Thus, in this representation, this requirement to initiate the radio connection establishment procedure results in success, ie establishment of the radio connection (eg receiving an RRC connection setup message) or failing (eg RRC connection rejection) It should be understood that it is irrelevant whether the message is received.

  As used in the claims and in the present application, the expression (and similar expressions) that "the radio resource pool for transmission is available" means that the terminal is directly (for example, scheduling assignment (SA) or direct communication data) In the broad sense, it should be understood in the sense that the terminal can (though not necessarily) select and use resources from the radio resource pool for transmission when it is desired to carry out communication transmission. Correspondingly, the expression (and similar expressions) that the radio resource pool for transmission is used is actually intended by the terminal to carry out direct communication transmission and is appropriate from the radio resource pool for transmission. Broadly understood as meaning selecting a resource and performing its direct communication transmission on that selected resource.

  As used in the claims and in the present application, the expression "in coverage" is used, as long as the terminal has successfully selected a cell, regardless of whether the terminal is idle or connected. It should be broadly understood as meaning that the terminal is considered to be in coverage. The criteria for cell selection are defined in Non-Patent Document 2. All in-coverage UEs are signaled from the network using broadcast messages (in idle or connected state) or using dedicated (ie one-to-one between UE and network) messages in connected state Can be received. For example, if the UE has a serving cell (ie, the UE is in the RRC_CONNECTED state or camped on the cell in the RRC_IDLE state), the UE is considered to be in coverage. Therefore, the expression "out of coverage" should be understood as the opposite meaning.

  The terms "preset" used in the claims and in the present application mean that the corresponding resource of the resource pool is known to the terminal, even without receiving any information from the radio access. That is, it should be broadly understood as meaning that the radio resource pool set in advance is available regardless of the cell and the system information broadcast in the cell.

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

  As described in the background section, the UE may use different resources for D2D direct communication with another UE, depending on its state and configuration by the eNB. The inventor has recognized a number of problems and drawbacks with respect to the currently considered implementation of direct communication (ie 3GPP D2D communication). The following various scenarios and problems exist, which are described in connection with FIG. FIG. 18 (an extension of FIG. 15), in addition to FIG. 15, shows the UE's interest in D2D communication, the UE requesting dedicated radio resources for transmission of D2D communication, and various different time periods 0, 1, 2, A, B, C, D are shown. Although not shown in FIG. 18, as described in the background section, the UE is pre-configured for reception / transmission of scheduling assignment (SA) and D2D data when it is out of coverage of the cell It can have mode 2 resources.

  The eNB may decide in its own network that mode 2 resource allocation can not be performed when the UE is in RRC idle state. For purposes of explanation, such a type of network is referred to as a type A network. In particular, in a type A network, the UE recognizes in the SIB 18 that D2D is permitted, but there is a common mode 2 resource (eg, resource pool according to mode 2) broadcast for D2D In order not to do so, the UE must first establish an RRC connection (see FIG. 15). Then, after the UE is properly configured for D2D (eg, using D2D communication interest notification and corresponding D2D communication response (see FIG. 16)), the UE responds to the configuration for the UE by UE (D2D communication response message Mode 2 resources can be accessed for transmission). If resources available for D2D communication (eg as a dedicated mode 2 resource pool) are not provided by the D2D communication response as described in the background section (steps in section "Transmission procedure in D2D communication" 1 to 5), the UE needs to explicitly request the resources associated with D2D using dedicated signaling (scheduling request, buffer status report), which takes more time (see period C) ).

  Furthermore, period D shown in FIG. 18 is a delay when sending the first D2D after receiving the corresponding D2D grant. This delay may be considered negligible but may not be negligible, as we have calculated that each scheduling assignment (SA) and resource pool bitmap period for data, their offset (eg SFN (eg Depending on resource settings such as the system frame number) offset from 0), T-RPT (time resource pattern of transmission) to be allocated, the period D alone can be about 300 to 400 ms.

  As a result, the UE can not execute D2D communication by the end of period 2 shown in FIG. 18, and furthermore, even if D2D is permitted by the D2D communication response from the eNB, the communication response is dedicated to the UE. If D2 mode 2 resources are not provided (in this case the UE needs to explicitly request a grant of resources for a specific D2D transmission), D2D communication may also be performed over period C and period D Can not.

  In a type A network, the network operator has complete control over resource usage. Because the network operator is aware of the number of UEs running D2D, and thus can distribute resources between D2D applications and LTE applications. However, UEs in such a type A network can not perform any D2D communication in idle state. Furthermore, even after being in the RRC connected state, the UE must send a D2D communication interest notification message, wait for at least an explicit network response to receive D2D communication resources, and actually send communication data It is necessary to wait an additional time (period C and / or period D) before it can be done. This delay can easily add up to 2 seconds or more. In Release 12, D2D communication is primarily intended for public safety applications, so a delay / interrupt of even 2 seconds is not acceptable, especially for VoIP / voice / conversation classes of service. This is especially true for UEs at the cell edge that may move between out-of-coverage and in-coverage situations. FIG. 17 shows a UE moving at the periphery of a cell.

  This problem is mitigated, in a limited manner, in another type of network where common mode 2 D2D communication resources used in RRC idle state are provided by network deployment by eNB. Such a network can be referred to as a type B network for purposes of illustration. In such a Type B network, the UE has acquired SIB 18 (including the corresponding Mode 2 idle resource setting (eg commIdleTxPool)) (and thus is more than in a Type A network) (Early) start D2D communication using such mode 2 idle resource. Thus, these UEs can perform D2D data communication shortly before the interruption occurs again in the periods B, C, D. Thus, the UE can not perform D2D communication in period 0, but can perform D2D communication during period A.

  However, even in the type B network, the UE is suppressed from performing D2D communication at a specific timing, which causes undesirable delays and / or interruptions. The UE may continue to use mode 2 idle state resources as long as it is in the RRC idle state. State-of-the-art mode 2 idle state resources via SIB 18 can only be used in RRC idle state. However, if the UE establishes an RRC connection (and for some reason, eg, for reasons of WAN (eg, to access the Internet)) and thus changes to an RRC connected state (see step 7 of FIG. 15), that UE Can no longer use these resources of the mode 2 resource pool defined by SIB 18 for the purpose of continuing or initiating D2D communication (ie, at the time of step 7 in FIG. 15). In such a case, the UE sends at least a D2D communication interest notification message and waits for an explicit network response to resume the previously initiated D2D communication or to start a new D2D communication, mode 2 D2D communication resources must be received (or when it is necessary to explicitly request a grant of resources for a particular D2D transmission, as described above in connection with steps 1 to 5 of the D2D communication transmission procedure) I have to wait a long time). This leads to communication delays and / or interruptions. The UE can not perform D2D communication in periods B, C (and D).

  FIG. 20 shows the various time periods described in FIG. 18 as blocks and illustrates the difference in time periods during which the UE can not transmit D2D communication for Type A and Type B networks.

  FIG. 19 is similar to FIG. 18, but shows a case where establishment of RRC connection fails. As apparent from the figure, after initiating the establishment of the RRC connection, the establishment fails (for example, because the RRC connection is rejected by the eNB, or for other reasons such as cell reselection, or T300 is broken Things can happen). In either case, the UE remains in RRC idle state. In a Type A network, such a situation is particularly disadvantageous. This is because the UE can not execute D2D communication at all while in the idle state. On the other hand, in the case of a type B network, D2D communication is possible after obtaining SIB 18 including setting of idle state resources of mode 2 (ie, during period A and later).

  One suitable (and easily implemented) solution for Type B networks is to at least allocate dedicated resources that can be used for direct communication transmission to the terminal by the eNodeB (period B + C in FIG. 18). (See (+ D)), to make the mode 2 idle state resource (commIdleTxPool) available also by the terminal in RRC connected state.

  The inventor has conceived the following first and second exemplary embodiments in order to alleviate the above mentioned problems.

  In the following, some exemplary embodiments will be described in detail. Some of these embodiments are intended to be implemented within the broad specifications given in part by the 3GPP standards (parts of which are described in the background section), and in particular the important features are: The description will be made in connection with various embodiments. It should be noted that although these embodiments may be advantageously used in mobile communication systems such as, for example, the 3GPP LTE-A (Release 10/11/12) communication system described in the background section, these embodiments It should be noted that the invention is not limited to use in this particular exemplary communication network.

  It is to be understood that the following description is not intended to limit the scope of the present disclosure, but is merely an example of an embodiment for a thorough understanding of the present disclosure. It will be appreciated by those skilled in the art that the general principles of the present disclosure as recited in the claims can be applied to various scenarios, in a manner not explicitly described herein. Thus, the following scenarios envisaged for the purpose of describing the various embodiments do not limit the invention to such scenarios.

First Embodiment
The first series of embodiments will be described below. In order to simplify the description of the principles of the first embodiment, several assumptions are made, which are interpreted as limiting the scope of the present application as broadly defined by the claims. It should be noted that it should not be.

  According to a first aspect, an additional transmitting radio resource pool for performing direct communication transmission is defined by the network operator, this additional resource pool being an idle state transmitting radio as already known from the prior art Resource pools differ in several ways. As described in the Background section, if the network operator decides to do this, information about the radio resource pool for transmission can be broadcasted by the base station in that cell. Therefore, the terminal that has received this system information broadcast can autonomously use resources from this transmission radio resource pool when it desires to execute direct communication with another terminal. The prior art radio resource pool for transmission (referred to for convenience as the radio resource pool for idle state transmission) can be used by the terminal while in the idle state, but when the state of the terminal changes to the connected state, the above mentioned problems Some of the occur.

  On the other hand, the additional transmission radio resource pool (referred to as a temporary transmission radio resource pool for convenience) introduced according to this first aspect is only temporarily (ie, over a limited length of time) ) But it is irrelevant whether the terminal is idle or connected. The network operator can control the length of time that this temporary transmission radio resource pool can be used by corresponding additional indication information (setting information) in the system information broadcast. Limiting the availability of this temporary transmission radio resource pool can be implemented in several different ways, some of which will be described exemplarily later, but in any way The time available for this temporary resource is limited and can be controlled by the base station (i.e. the network operator).

  The network operator has complete control (or at least as much control as possible) on its radio resources, in terms of making the radio resource pool for idle transmission commonly available to the terminals via system information broadcast. It is possible to choose to assign a specific dedicated resource pool to specific terminals, or to assign only specific dedicated physical resources to each terminal, such that Thus, the network operator may not want the terminal to autonomously use the prior art idle resource radio resource pool in its cell. The reason is, for example, that the terminal can use the resource from this idle transmission radio resource pool almost unlimitedly (as long as the terminal is idle), or in the case of using autonomously, The network does not know if the UE is actually using these idle mode D2D resources, because the network can not know about the number of such UEs (UE in idle mode is recognized at cell level) It is recognized only at the tracking area level sufficiently larger than the cell level). Thus, the network determines whether this idle mode D2D resource is too low (ie, there are many collisions in the use of D2D resources) or too much (ie, it would otherwise unnecessarily consume LTE resources). Can not do it. On the other hand, in the case of an additional temporary radio resource pool for transmission, the network operator accurately defines physical resources that can be used over a configurable amount of time (albeit to a lesser extent) can do. Of course, as a direct benefit of this method, the terminal accesses the resources for direct communication transmission immediately upon receiving and processing the corresponding system information broadcast containing information on the temporary transmission radio resource pool. be able to. On the other hand, the network operator can flexibly control the time when such resources are commonly available to the terminal in the terminal's cell. Since the number of UEs establishing RRC connection is much less than the total number of UEs in idle mode in the cell, the additional temporary radio resource pool for temporary transmission is broadcasted in SIB 18 in the prior art (see Compared with the mode 2) idle state transmission radio resource pool, it can be sufficiently efficient / small in size. The additional temporary radio resource pool for transmission is particularly advantageous for terminals existing in a cell that does not actually provide such an idle radio resource pool for idle state. However, the additional temporary transmission radio resource pool is also advantageous for terminals in the other type of cell that actually broadcasts the idle transmission radio resource pool. Because, in that case, when the terminal is already in the connected state but dedicated resources for direct communication transmission are not allocated yet by the base station, or when the terminal is not actually transmitting data for D2D communication yet Also, resources for direct communication transmission are available.

  In summary, by providing the temporary transmission radio resource pool of the first aspect in the system information broadcast of the cell instead of or in addition to the prior art radio resource pool for idle state transmission , Delays or interruptions of direct communication of terminals are reduced or almost eliminated, and at the same time the network operator is given as much control over such resources as possible. Although different depending on the specific implementation, in a cell of type A network (that is, the system information does not include the idle transmission radio resource pool), the terminal receives the above-mentioned temporary transmission radio resource pool. Resources can be used from this resource pool after, that is, during period A, period B, period C, and period D shown in FIG. In a cell of type B network, the terminal may use resources from the temporary transmission radio resource pool for the period B + C + D.

  A further implementation of the first aspect relates to a method of limiting, by means of configuration information, the length of time that a temporary transmitting radio resource pool can be used by transmitting terminals in a cell. For example, the system information broadcast can directly indicate the appropriate time length (eg, 10 ms, 100 ms, 2000 ms) of the temporary transmission radio resource pool. In this case, although different depending on the specific implementation, the terminal may use this indicated time length, for example, a temporary transmission radio resource pool for the specific time after receiving the system information broadcast. Interpret as Alternatively, instead of activating the timer when the terminal receives a system information broadcast, the transmitting terminal may transmit (for example, by sending a scheduling assignment to another terminal in direct communication transmission) a temporary transmission radio resource pool. The timer can be started when the use is started. In any case, as a particular benefit of this method, such a configuration is independent of the wireless connection establishment procedure and its consequences, and thus predictable by the base station.

  A temporary transmission radio resource pool is available by specifying a specific condition / event that causes the terminal to stop using this resource further instead of directly indicating the length of time. Time can be limited "indirectly". For example, a terminal desiring to use these resources as an indication related to a temporary transmission radio resource pool may avoid that the terminal remains idle and uses such resources indefinitely, An indication that further attempts to establish a wireless connection with the base station should be made can be included in the system information broadcast. In this case, the terminal uses resources from its temporary transmission radio resource pool only while the connection is established and dedicated radio resources are allocated to the terminal by the base station (see period A + B + C in FIG. 18). And the dedicated radio resource is used instead for direct communication transmission after the dedicated radio resource is allocated. Alternatively, if the connection can not be established or the connection is refused, the temporary transmission radio resource pool is only transmitted until the terminal is notified of the failure of the establishment (see period A in FIG. 19). The terminal is allowed to use resources from Alternatively, at that time, the base station may establish a connection with the terminal but not permit the terminal to perform direct communication transmission (see period A + B in FIG. 18). Furthermore, in view of the fact that it may take a long time for the terminal to actually use the dedicated radio resource allocated to the terminal by the base station, in a further alternative scheme, the terminal Establishment and after receiving dedicated radio resources for direct communication transmission from the base station), using these dedicated radio resources allocated to the terminal by the base station for scheduling assignment (SA) or direct communication transmission of data Until the time of execution (see period A + B + C + D in FIG. 18), the time for which the temporary transmission radio resource pool is available can be extended.

  The actual indication to establish the connection is, for example, a specific length of time, within which time the terminal (at least) starts establishing the connection (eg immediately after receiving the system information broadcast, or temporarily sending It can indicate the required length of time to start immediately after starting to use the trusted radio resource pool. As yet another option, the terminal is requested to initiate connection establishment before being permitted to use radio resources from the temporary transmission radio resource pool for direct communication transmission. To this end, the terminal can be understood as initiating establishment of a connection with a base station by transmitting, for example, a preamble of a random access procedure.

  In addition to this, in the first aspect, as in the case of the prior art wireless resource pool for idle state transmission, in a temporary transmission wireless resource pool, scheduling assignment (SA) is carried out through another link through another direct link. It is possible to distinguish between the resources available for direct communication transmission to and from the resources available for direct communication transmission of "direct" data to another terminal via a direct link. Thus, the cell can provide different resources for transmission of scheduling assignments (SAs) and transmission of data.

  So far, several different implementations of the first aspect have been described. In the following, the principles behind this first aspect and its implementation are exemplarily applied to an LTE system (such as the LTE system described in the background section).

  In particular, the current standardization by 3GPP considers the inclusion of some information related to ProSe direct communication and direct discovery using SIB18. Therefore, the information on the above-mentioned temporary transmission radio resource pool and its setting information can be part of this SIB type 18. Of course, it should be noted that for the purpose of this first aspect, this information can be conveyed using any other type of system information block. Furthermore, in a specific example, a selected field in the system information block for conveying a temporary transmission radio resource pool and its configuration information is referred to as "commTxPoolTemp". Again, for purposes of this aspect, any other name may be chosen for this field, or information regarding the temporary transmit radio resource pool may be placed in another field of the corresponding configuration information. Note that it can be inserted. The same applies to the names and formats chosen for the specific variables commSA-TxResourcePoolCommonTemp and commData-TxResourcePoolCommonTemp.

Thus, the following definition of an information element of system information block type 18 is to be understood as an example only.

  In a first aspect, significant changes introduced to the information element of this exemplary system information block type 18 as compared to the prior art are bolded and underlined for easy recognition. As is apparent from the table, in this particular example, the configuration information is implemented as the variable "allowedTime", which takes 100 ms, 200 ms, etc. as an example time value as described above, Therefore, the time length is directly limited. Of course, these specific time values and the number of time values that can be set should be understood as examples only. Any other time value and the number of configurable time values can be chosen accordingly. The terminal receives its system information broadcast by reading the value indicated by the variable "allowedTime" (or the terminal starts using resources from the temporary transmission radio resource pool to perform direct communication) After that, it is possible to determine the length of time that the temporary transmission radio resource pool can be used. The UE may configure and activate corresponding timers to monitor.

As a further alternative, another example of the definition of SIB 18 is shown below. As with the exemplary definitions above, the names given to variables and the specific values given to variables should be understood as examples only.

  In a first aspect, significant changes introduced to the information element of this exemplary system information block type 18 as compared to the prior art are bolded and underlined for easy recognition. As is apparent from the above table, the configuration variable timeToInitiateRRCConnEst is included to indirectly limit the use of the temporary transmission radio resource pool (ie commTxPoolTemp) based on different termination conditions as will be explained later. It is done. By using this configuration variable timeToInitiateRRCConnEst, the UE is instructed to attempt to establish an RRC connection with the eNB in a time such as 1 ms or 5 ms, which is an exemplary time as indicated above. Depending on various behaviors of the UE, for example, until an RRC connection is established and the eNB allocates dedicated radio resources to the terminal, or until the UE recognizes that the RRC connection has failed to be established, or in a cell The UE until the eNB notifies the UE that direct communication is not permitted to be performed, or until it actually performs a scheduling assignment (SA) or direct communication of data using dedicated resources assigned to the UE by the eNB In addition, it is possible to permit the use of resources of the temporary transmission radio resource pool.

  Furthermore, it should be noted that this new field commTxPoolTemp is an option in SIB 18, so the decision on whether to broadcast this field in the cell is left to the network operator. As the commIdleTxPool field (previously defined in the state of the art) is also optional, as a result the network operator sets one or both of the commIdleTxPool field and the commTxPoolTemp field (via the eNB) as required, or Neither can be set.

  Of course, it is also possible to combine the multiple definitions of SIB 18 shown above, so that the commTxPoolTemp field can be set to include the variables “allowedTime” and “timeToInitiateRRCConnEst”.

Second Embodiment
The second aspect of the invention also solves the above-mentioned problems inherent in the prior art, but in a different way. Instead of defining an additional transmitting radio resource pool in the system information broadcast as done in the first aspect, this second aspect relates to transmitting radio resource pool, which is preset, Not only when the terminal is out of the coverage of the cell, but also when the terminal is in the coverage of the cell, as it is currently defined, as it is used for direct communication transmission. In this context, "preconfigured" is distinguished from "configured" resources configured by system information broadcast from the base station. In other words, the pre-set resources are known to the terminal (and base station), for example, even without receiving any information from the radio access, ie independently of the cell and the system information broadcast in the cell. is there. The preconfigured radio resources belong to the state of the art itself and are already used by UEs that are outside the coverage of the cell (ie no system information broadcast has been received from the cell's base station).

  For example, a preset radio resource pool for transmission can be defined by a network operator and hard coded into a common sim / USIM card that can be inserted and used in the most common mobile phones. Alternatively, the appropriate information on such a preconfigured radio resource pool for transmission is provided to the terminal using higher layer signaling (eg from core network via internet protocol or non-access layer protocol) can do.

  The terminal can perform direct communication transmission also by using radio resources from a preset radio resource pool for transmission, even when it is within the coverage of a cell. This means that the system information broadcast is received by itself, whether the system information broadcast includes information on a resource pool, whether a wireless connection is established or not, which state the terminal is currently in (idle state or connection state) It has nothing to do with Thus, the terminal is not throttled, delayed or interrupted for direct communication transmission. Therefore, unlike the first embodiment, according to the second aspect, the terminal can perform direct communication transmission also in period 0 in addition to periods A, B, C, and D.

  One option is to apply the preconfigured radio resource pool for transmission, which is already defined in the latest technology for terminals out of coverage, to terminals within the coverage of the base station's cell. It is to reset to.

  On the other hand, alternative options are new pre-configured intra-coverage transmissions, in addition to the pre-configured radio resource pools for transmissions already defined in the state of the art for out-of-coverage terminals. It is to set up a trusted radio resource pool (in-coverage configured transmission radio resource pool), and this preset in-coverage transmission radio resource pool is applied to terminals within the coverage, but it is still a base station. Terminals that are out of coverage of the cell can not be used. In this case, sim / USIM is both a preset transmission radio resource pool targeted for out-of-coverage of the latest technology and a preset in-coverage transmission resource resource pool according to the second aspect. It may be stored on the card, or alternatively be defined by higher layer signaling as described above.

  In a further development of the second aspect, the network operator sets this preconfigured radio resource pool for transmission (even if this resource pool is preconfigured for a particular terminal). Provides some control over what is actually available in your cell. For example, the network operator can decide that the resources of these preset radio resource resource pools for transmission are not available to the terminal in its own cell. For this purpose, the system information broadcast appropriately indicates whether or not the use of the transmission radio resource pool set in advance is permitted to the terminal within the coverage of the cell.

  One possible and simple way to indicate this is a 1-bit flag in the system information, one bit value being the radio for transmission preset for the terminals in the coverage of the cell Indicates that use of the resource pool is permitted, and the other bit value indicates that it is not permitted.

  Alternatively, the system information may include, as an option, setting information of the transmission radio resource pool set in advance, and when the setting information does not exist, the terminal may transmit radio resource set in advance. Recognize that the pool is not used. On the other hand, setting information on a transmission radio resource pool set in advance exists in the system information. Thus, when received by a terminal attached to a cell, that terminal can continue to use the preconfigured transmission radio resource pool for direct communication transmission, but its configuration information regarding the use of this resource pool It recognizes that it applies further.

  The configuration information can take various forms. For example, according to a refinement of the second aspect, it is advantageous to also temporally limit the use of this preset radio resource pool for transmission while within the coverage of the cell. As described in connection with the first aspect, there are several possible ways to limit the length of time that a particular radio resource pool is available to the terminal. Therefore, the setting information of the transmission radio resource pool set in advance may be similar to or the same as the setting information described above in the case of the temporary transmission radio resource pool.

  In detail, the system information broadcast can indicate, for example, directly (eg, 10 ms, 100 ms, 2000 ms) an appropriate time length of the transmission radio resource pool set in advance. In this case, although different depending on the specific implementation, the terminal can use this indicated time length for the specified time, for example, after the preset radio resource pool for transmission has received the system information broadcast. Interpreted as something. Alternatively, instead of activating the timer when the terminal receives a system information broadcast, the sending terminal is preconfigured transmission (eg by sending a scheduling assignment (SA) to another terminal in direct communication transmission) A timer can be started when the use of the trusted radio resource pool is started.

  Instead of directly indicating the length of time, or in addition to this, the preset radio resource pool for transmission is used by specifying a specific condition / event that causes the terminal to stop using this resource further The time that is possible can be "indirectly" limited. For example, a terminal desiring to use these resources as an indication associated with a preset radio resource pool for transmission prevents the terminal from remaining idle and using such resources indefinitely. Therefore, the system information broadcast can include an indication that it should further attempt to establish a wireless connection with the base station. In this case, the terminal is able to use the resources from the transmission radio resource pool set in advance only during the time when the connection is established and the base station allocates dedicated radio resources to the terminal (see period 0 + A + B + C in FIG. For direct communication transmission after being permitted to use and dedicated radio resources are allocated, the dedicated radio resources are instead used. Alternatively, if the connection can not be established or the connection is refused, the temporary transmission radio resource pool is only transmitted until the terminal is notified of the establishment failure (see period 0 + A in FIG. 19). The terminal is allowed to use resources from Or, at that time, the base station may establish a connection with the terminal but not allow the terminal to perform direct communication transmission (see period 0 + A + B in FIG. 18). Furthermore, in view of the fact that it may take a long time for the terminal to actually use the dedicated radio resource allocated to the terminal by the base station, in a further alternative scheme, the terminal Establishment and after receiving dedicated radio resources for direct communication transmission from the base station), using these dedicated radio resources allocated to the terminal by the base station for scheduling assignment (SA) or direct communication transmission of data Until the time of execution (see period 0 + A + B + C + D in FIG. 18), the time for which the preset radio resource pool for transmission can be used can be extended.

  The actual indication to establish the connection is, for example, a specific length of time, within which time the terminal (at least) starts establishing the connection (eg immediately after receiving the system information broadcast, or pre-set) Can be indicated immediately after the start of use of the transmission radio resource pool). As yet another option, the terminal is requested to initiate connection establishment before being permitted to use radio resources from a preset radio resource pool for direct communication transmission. To this end, the terminal can be understood as initiating establishment of a connection with a base station by transmitting, for example, a preamble of a random access procedure.

  The preconfigured radio resource pool for transmission can define the actual physical radio resources (ie time and frequency) and optionally also define the particular transmission format or transmission power associated with the physical radio resources Can. Furthermore, when the terminal is in coverage and uses a preconfigured radio resource pool for transmission for direct communication transmission, the power of those transmissions can be controlled by the base station (in a conventional manner).

  So far, several different implementations of the second aspect have been described. In the following, the second aspect and the principle behind its implementation are exemplarily applied to an LTE system (such as the LTE system described in the background section).

  According to some implementations described above in relation to the second aspect, to allow / do not allow the use of the pre-configured radio resource pool for transmission when within coverage, and / or this resource Modify the system information broadcast from the base station to configure the use of.

As described in the first aspect, the current standardization by 3GPP considers that some information related to ProSe direct communication and direct discovery is included using SIB 18, and SIB 18 is mentioned above. It can communicate flags and configuration information. Of course, it should be noted that for the purpose of this second aspect, any other type of system information block can be used to convey these information. Below, a very specific example is shown. Configurations and configuration variables have specific names (ie, usePreconfigResInCoverage, allowedTime, timeToInitiateRRCConnEst), and these variables are specifically configured (ie, ms100, ms200, ms300, etc., ms01, ms05, etc.) ). Again, it is to be noted that for the purpose of this second aspect, any other name can be chosen for the field, and the actual value of the variable can be a different value.

  In a second aspect, the significant changes introduced to the information element of this exemplary system information block type 18 as compared to the prior art are bolded and underlined for easy recognition.

  As apparent from the above table, the field "usePreconfigResInCoverage" of the configuration information is optional, and therefore, when this field is present in the system information broadcast, the corresponding UE will be in coverage. It can be recognized that the transmission radio resource pool (the resource of mode 2) set in advance is available. Conversely, when this field is not present, the UE recognizes that the corresponding preset radio resource pool for transmission is not available in that cell.

  The configuration variables "allowedTime" and "timeToInitiateRRCConnEst" are themselves as already described in the first aspect and are likewise defined in this second aspect. As is evident from the above example, these configuration variables can also be defined at the same time (if the eNB so decides), which enables the use of a preconfigured radio resource pool for in-coverage transmission. The length of time that is can be limited directly and / or indirectly. Thus, in this particular example, part of the configuration information is implemented as the variable "allowedTime", and exemplary time values are 100 ms, 200 ms, etc. as indicated above, thus the time length Directly limit. The terminal has received a system information broadcast by reading the value indicated by the variable "allowedTime" (or started using resources from the temporary transmission radio resource pool for the terminal to perform direct communication) After), it is possible to determine the length of time that the preset radio resource pool for transmission is available. The UE may configure, activate and monitor corresponding timers.

  Similarly, the configuration variable “timeToInitiateRRCConnEst” can be included to indirectly limit the use of the temporary transmission radio resource pool (ie, commTxPoolTemp) based on different termination conditions as described later. By using this configuration variable timeToInitiateRRCConnEst, the UE is instructed to attempt to establish an RRC connection with the eNB for an exemplary time, such as 1 ms or 5 ms as indicated above. Depending on various behaviors of the UE, for example, until an RRC connection is established and the eNB allocates dedicated radio resources to the terminal, or until the UE recognizes that the RRC connection has failed to be established, or in a cell Until the eNB notifies the UE that the execution of the direct communication is not permitted, or until it actually performs the scheduling assignment (SA) or direct communication of data using dedicated resources allocated to the UE by the eNB. The UE can be permitted to use the resources of the transmission radio resource pool set in advance.

  Furthermore, although this second embodiment has been described as a single solution that differs from the first embodiment, in general this second embodiment can be combined with the first embodiment .

Third Embodiment
The inventor has recognized further problems in connection with D2D communication and current developments. More specifically, apart from the above mentioned problem of the UE being restrained from performing D2D communication for various time periods in different scenarios, another problem is the out of state 3 (OOC) UE and the state 4 It relates to out-of-coverage (OOC) UEs. Specifically, the method by which a particular UE recognizes whether it is in state 3 (CP UE relay) or state 4 is not yet clear. This leads to additional problems, and the UE is not clear about the resources and transmit power to use to perform D2D communication.

FIG. 11 and the corresponding descriptions in the Background section describe the four general states that the UE can take. These states are summarized as follows.
State 1: Within the coverage of the cell (IC) (very close to the center of the cell)
State 2: Within cell coverage (IC) (periphery of cell)
State 3: out of cell coverage (immediately outside the cell). Such UEs may generate some WAN interference "if they transmit" at high transmit power on colliding resources.
State 4: Outside the cell's "true" coverage. Even transmitting at high transmit power on conflicting resources does not cause any kind of WAN interference.

  Clearly, the UE is out of coverage of the cell in both state 3 and state 4, but the way the UE distinguishes between state 3 and state 4 is unclear. The reason is that the UE only recognizes that it is not within the coverage of the cell (ie not camped on any WAN cell).

  The following solutions are possible.

  If the UE receives PD2DSCH, it considers itself to be state 3 and if it has not received PD2DSCH for a specific predefined (or configurable) time, it considers itself to be state 4 . The PD2DSCH is physical layer information sent by the eNB to the OOC (out-of-coverage) UE via some in-coverage (IC) UEs as described in the background section (in-coverage (IC) UE Transfer PD2 DSCH). The PD2 DSCH signals some resources for D2D communication. When received by the OOC (out of coverage) UE, the resources received in the PD2 DSCH for D2D communication are prioritized over the pre-configured mode 2 resources available to the OOC (out of coverage) UE. This is advantageous because, without taking such measures, these UEs may consider themselves to be in state 4 and may transmit with high transmit power on conflicting resources, pre-configured mode 2 Some WAN interference may occur by using the following resources.

  The UE in state 3 regards itself again as the UE in state 4 when reception of PD2 DSCH or D2 DSS (D2D synchronization signal) has been suspended for a predefined period.

  The resource that the UE should use to perform D2D communication so that no problem (interference) with the WAN communication is caused by specifying how the UE distinguishes state 3 and state 4 in this way And transmit power can be efficiently selected / calculated.

  It should be noted that the third embodiment described above can be combined with the first embodiment and / or the second embodiment described above.

Fourth Embodiment
As another issue recognized for D2D communication, it is unclear in the current standardization which UEs are responsible for transferring PD2 DSCH to out-of-coverage (OOC) UEs.

  The following alternative solutions are possible. It is also possible to combine the following solutions.

  In general, UEs that are well within the coverage of the cell (eg good measurement of RSRP and RSRQ of the serving cell) but not near the center of the cell may be good candidates for transferring PD2 DSCH. . Specifically, a specific wireless reception value is between predefined thresholds (eg, RSRP (reference signal reception power) / RSRQ (reference signal reception quality) measurement value is a specific threshold value. Between the “x” and the threshold “y”). In such case, threshold x and threshold y are broadcast along with the contents of PD2 DSCH.

  Another possible candidate for transferring PD2 DSCH is a UE that transmits / transfers D2 DSS. The contents of PD2DSCH are broadcasted.

  Another possible solution is for the network to explicitly request specific UEs in dedicated signaling to forward PD2 DSCH. The contents of the PD2 DSCH may be broadcast or signaled to the UE by dedicated signaling.

  One possible combination of the above solutions is the UE that has already transferred D2 DSS and is well within the coverage of the cell (ie between RSRP or RSRQ corresponding thresholds).

  It is noted that the fourth embodiment can be used together with any of the first embodiment, the second embodiment and the third embodiment, or together with any combination thereof. I want to.

Fifth Embodiment
Yet another issue that is recognized for D2D communication relates to the receive / transmit operation in D2D communication. As described in the background section, the transmission behavior of D2D communication differs slightly depending on the resource allocation mode. For mode 1 D2D communication, the eNB issues a D2D grant (ie (E) PDCCH scrambled by D2D-RNTI) to the D2D sender UE, which D2D grant is for transmission of scheduling assignment (SA) Not only resources but also resources for data (ProSe / D2D data) are allocated. More specifically, this D2D grant is at least used by the D2D sender UE to transmit the scheduling assignment (SA) resource index (SA resource index) (scheduling assignment (SA)), within the SA resource pool. It includes a time / frequency resource), a T-RPT index field and a data RB assignment field (indicating time / frequency resources basically for D2D data transmission). The T-RPT index field refers to an entry in a table (this table contains, for example, 128 entries) listing all available T-RPT patterns. The transmission time resource pattern (T-RPT pattern) defines the time resource pattern of D2D data transmission in the D2D data resource pool.

  When the D2D transmitting UE receives the D2D grant from the eNB, it uses the SA resource index in order to determine, within the SA resource pool, subframes and frequency resources to be used for transmission or retransmission of scheduling assignment (SA) messages. . Furthermore, the D2D transmitting UE is at least a D2D grant for the purpose of determining subframes (and in some cases, frequency resources based on some other information conveyed in the D2D grant) to be used for transmission of D2D data PDUs. Use the received T-RPT index information. The functions for deriving subframes for transmission of D2D data PDUs are different for mode 1 D2D transmission and mode 2 D2D transmission. For mode 2 D2D transmission, the D2D sender UE applies the T-RPT pattern to subframes represented as 1 in the resource pool bitmap. Basically, the D2D transmitting UE applies the T-RPT pattern to subframes defined as D2D subframes usable for mode 2 transmission according to the mode 2 D2D data transmission resource pool. An example is shown in FIG.

  The 1 in the transmission resource pool bitmap represents a so-called D2D subframe (i.e., a subframe reserved for mode 2 D2D transmission). T-RPT patterns are applied to these D2D subframes. As can be understood in FIG. 22, D2D subframes in which the corresponding T-RPT entry is 1 (subframes in which both the resource pool bitmap entry and the T-RPT bitmap entry are 1) are D2D data Used for sending PDUs. As already explained in the background art, for mode 2 resource allocation, the D2D sender UE autonomously selects the T-RPT pattern and signals it in the scheduling allocation (SA). Thus, the D2D receiver UE can determine the time / frequency resource of D2D data transmission based on the received T-RPT pattern (after successfully decoding the scheduling assignment (SA)). For mode 2 D2D transmission, there is no D2D grant.

  For mode 1 D2D transmission, as already mentioned above, the eNB allocates a T-RPT pattern to be used for D2D transmission and signals it to the D2D transmitting UE via D2D grant.

  In the case of mode 1, taking into account that there is no resource pool for D2D transmission, the T-RPT parameters are applied directly to the physical uplink subframes. This is because all uplink subframes can be D2D subframes. According to an exemplary embodiment, the D2D transmitting UE determines the T-RPT pattern indicated by the T-RPT pattern index in the D2D grant to all subframes in the resource pool's bitmap (ie, the bitmap). This applies to subframes in which the entry is 1 and subframes in which the entry is 0). An example of mode 1 D2D data transmission is shown in FIG.

  As can be understood from the figure, again, the same T-RPT pattern as used in the exemplary scenario described for mode 2 D2D transmission is used as an example. However, in mode 1, the T-RPT pattern is applied to all (uplink) subframes in the resource pool. In the case of mode 1, since the resource pool for data transmission is not defined / set up, the D2D transmitting UE applies the T-RPT pattern to either the data transmission resource pool of mode 2 or the data reception resource pool. be able to. What is important is that some reference subframe when applying the T-RPT pattern in mode 1, ie, the start subframe, is required. Alternatively, some timing relationship between the initial transmission of D2D data and the scheduling assignment (SA) can be predefined. For example, the first transmission opportunity for D2D data in mode 1 (ie, this is the start subframe of the T-RPT pattern) occurs x ms after the previous transmission of a scheduling assignment (SA) message.

  Depending on whether D2D data transmission of mode 1 or D2D data transmission of mode 2 is used by the D2D transmitter UE, the usage of the T-RPT pattern differs. Therefore, the D2D receiver UE needs to be able to distinguish between the mode 1 D2D data transmission and the mode 2 D2D data transmission. More specifically, when the D2D receiver UE receives the scheduling assignment (SA) in the SA resource pool, it can correctly interpret the T-RPT pattern (ie, the correct time of the corresponding D2D data transmission / In order to determine frequency resources) it needs to be able to know whether the scheduling assignment (SA) was sent by mode 1 D2D data transmission or by mode 2 D2D data transmission. According to another exemplary embodiment, the scheduling assignment (SA) message includes an explicit indicator of the resource assignment mode used for D2D communication. That is, a new field in the scheduling assignment (SA) message indicates whether mode 1 or mode 2 was used for D2D data transmission.

  As an alternative solution, the transmission / resource assignment mode is implicitly indicated by the T-RPT pattern signaled in the scheduling assignment (SA) message. The available T-RPT patterns preset or given in table form are divided into two sets, one set of T-RPT patterns is used for mode 1 transmission and two of the T-RPT patterns The second set is used for mode 2. For example, assuming 128 different T-RPT patterns, patterns 0-63 can be used for mode 1 D2D transmission, and indexes 64-127 T-RPT patterns are reserved for mode 2. The D2D receiver UE should be aware of whether the transmitting UE is using resource allocation mode 1 or using mode 2 based on the received T-RPT index in the scheduling allocation (SA) Can.

  As a further alternative solution according to yet another exemplary embodiment, the resource assignment / transmission mode can be derived from the value of the TA field contained in the scheduling assignment (SA). The mode 1 transmission and the mode 2 transmission use different transmission timings, so the receiving UE can distinguish between the mode 1 transmission and the mode 2 transmission based on the value of the TA field. For example, the TA value for mode 2 transmission is always 0, whereas in mode 1 the TA value is set to the UE's NTA value (ie the UE is a legacy uplink in mode 1 D2D transmission Use transmit timing).

  As a further alternative, the resource assignment / transmission mode can be implicitly indicated by the frequency resources used for transmission of scheduling assignment (SA) messages. For example, the scheduling assignment (SA) message transmitted by the mode 2 transmitting UE and the scheduling assignment (SA) message transmitted by the mode 1 transmitting UE differ in frequency resources used. More specifically, the SA transmission resource pool for mode 2 is different from the resources (mode 1) allocated by the eNB for transmission of scheduling allocation (SA).

  Yet another alternative solution according to a further exemplary embodiment of the present invention defines the length of the T-RPT pattern bitmap so that it is not necessary to distinguish between mode 1 and mode 2 transmissions. It is to be. More specifically, the length of the T-RPT pattern bitmap should be the same as the length of the resource pool bitmap to which the T-RPT pattern applies. Taking the examples shown in FIGS. 21 and 22 described above, the length of the T-RPT pattern should be 30 bits.

  Since both T-RPT patterns in mode 1 and mode 2 apply to the same start subframe (eg, start subframe of resource pool), the D2D receiver UE can distinguish between mode 2 transmission and mode 1 transmission. There is no need to

  Note that the fifth embodiment is together with any of the first embodiment, second embodiment, third embodiment, and fourth embodiment, or together with any combination thereof. Please note that it can be used.

[Implementation of the present disclosure by hardware and software]
Another exemplary embodiment relates to the implementation of the various embodiments described above using hardware and software. In connection with this, user equipment (mobile terminal) and eNodeB (base station) are provided. The user terminal and the base station are adapted to carry out the method described herein.

  It is further recognized that the various embodiments of the invention may be implemented or carried out using a computing device (processor). The computing device or processor may be, for example, a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), Or other programmable logic devices. Various embodiments of the invention may also be practiced or embodied by a combination of these devices.

  Furthermore, various embodiments of the invention may also be implemented by means of software modules. These software modules may be executed by a processor or directly in hardware. Also, a combination of software modules and hardware implementation is possible. The software modules may be stored on any type of computer readable storage medium, such as RAM or EPROM, EEPROM, flash memory, registers, hard disk, CD-ROM, DVD, etc.

  Furthermore, it should be noted that the individual features of the plurality of different embodiments may individually or in any combination be the subject of another embodiment.

  It will be appreciated by those skilled in the art that various changes and / or modifications may be made to the disclosure as set forth in the specific embodiments. Accordingly, the embodiments of the present disclosure are to be considered in all respects as illustrative and not restrictive.

Claims (2)

An integrated circuit for controlling processing of a transmitting terminal performing direct communication transmission to a receiving terminal through a direct link connection in a communication system, the processing comprising
A process of receiving a system information broadcast from a base station;
The system information broadcast is
-A radio resource pool for idle state transmission or a temporary transmission, indicating by the transmitting terminal receiving said system information broadcast the radio resources available for performing direct communication transmission to the receiving terminal over the direct link connection. With a trusted radio resource pool,
-The transmitting terminal is required to initiate a radio connection establishment procedure with the base station before using the temporary transmission radio resource pool;
Configuration information on the temporary transmission radio resource pool including:
Information about, including
A process of selecting a radio resource from the idle state transmission radio resource pool or the temporary transmission radio resource pool;
The idle state transmission radio resource pool can be used only when the transmitting terminal is in the idle state,
The process of selecting the radio resource includes the idle state transmission radio resource pool when the system information broadcast includes setting information on the idle state transmission radio resource pool and the transmitting terminal is in the idle state. Is selected as a radio resource,
In the process of selecting the radio resource, when the system information broadcast does not include setting information on the idle state transmission radio resource pool, and includes setting information on the temporary transmission radio resource pool. Wireless resource pool for general transmission as a radio resource,
When the temporary transmission radio resource pool is selected as a radio resource, a radio connection establishment procedure with the base station is started, and then direct communication transmission of either scheduling assignment or data to the receiving side terminal is performed. Transmitting processing performed using the selected radio resource,
including,
Integrated circuit. The temporary transmission radio resource pool is up to any of the following:
-Dedicated radio resources available for performing direct communication transmission are allocated by the base station to the transmitting terminal.
The transmitting terminal initially performs direct communication transmission using a dedicated radio resource assigned by the base station to the transmitting terminal;
The wireless connection establishment procedure initiated by the sending terminal fails
Only by the sending terminal,
The dedicated radio resource is a radio resource selectable from an assigned radio resource pool for transmission allocated by the base station to the transmitting terminal, or the dedicated radio resource is for direct communication transmission A radio resource allocated to the transmitting terminal by the base station in response to a resource request from the transmitting terminal;
An integrated circuit according to claim 1.