Method and apparatus for transmitting v2x signal of user equipment in wireless communication system

Abstract

A method and apparatus for transmitting a sidelink signal of a user equipment in a wireless communication system are provided. A vehicle-to-everything (V2X) signal transmission method of a terminal having a limited transmission capability in a multicarrier system and a terminal using the method are provided. The method is characterized by selecting a first resource in a first carrier, if a transmission capability of the terminal is exceeded according to the first resource when a specific subframe is used in a second carrier, randomly selecting a second resource in the second carrier among remaining subframes except for the specific subframe, and transmitting a V2X signal by means of the first resource and the second resource.

Description

[0001] This application is a divisional application of patent application No. 201880031446.7 (PCT / KR2018 / 005355), filed on November 12, 2019, with a filing date of May 10, 2018, entitled "V2X signal transmission method for a terminal with limited transmission capability in a multi-carrier system and a terminal using the method". Technical Field

[0002] This disclosure relates to wireless communication, and more specifically, to a method for transmitting V2X signals for a terminal with limited transmission capabilities and a terminal using the method. Background Technology

[0003] There is increasing interest in device-to-device (D2D) technologies, where devices perform direct communication. In particular, D2D has garnered significant attention as a communication technology for public safety networks. Public safety networks have higher service requirements (reliability and security) than commercial communication networks. Specifically, public safety networks also require direct communication between devices, i.e., D2D operation, if cellular coverage is unaffected or unavailable.

[0004] D2D operation offers various advantages due to its nature as communication between neighboring devices. For example, D2D UEs offer high transmission rates and low latency, and can perform data communication. Furthermore, in D2D operation, services centralized at the base station can be distributed. If a D2D UE acts as a relay station, it can also extend the coverage of the base station.

[0005] Meanwhile, in LTE-A Advanced, the interface between terminals is called a sidelink, and the sidelink can also be used for communication between terminals installed in a vehicle or between a terminal installed in a vehicle and another arbitrary terminal, i.e., vehicle-to-everything (V2X) communication.

[0006] Traditional V2X communication does not support carrier aggregation. Carrier aggregation means that carriers can be combined and are classified as either the aggregation of consecutive carriers or the aggregation of non-consecutive carriers.

[0007] When carrier aggregation is used in V2X communication, a terminal can transmit V2X signals by using multiple carriers. However, a terminal is not always able to transmit V2X signals simultaneously on all configured carriers. For example, if the number of provided transmission chains is less than the number of configured carriers, the terminal cannot simultaneously support V2X signal transmission on all configured carriers.

[0008] When carrier aggregation is used for V2X communication for terminals with such limited transmission capabilities, the choice of how the terminal selects transmission resources becomes a problem. Summary of the Invention

[0009] The purpose of this disclosure is to provide a method for transmitting V2X signals by a terminal with limited transmission capacity in a multi-carrier system, and a terminal using the method.

[0010] In one aspect, a method is provided for transmitting vehicle-to-everything (V2X) signals performed by a user equipment (UE) with limited transmission capacity in a multi-carrier system. The method includes: selecting a first resource in a first carrier; if, considering the first resource, using a specific subframe in a second carrier exceeds the UE's transmission capacity, then randomly selecting a second resource in the second carrier from among the remaining subframes other than the specific subframe; and using the first and second resources to transmit the V2X signals.

[0011] In a specific subframe, the number of transport chains used for the UE can be less than the number of configured transport carriers.

[0012] The UE may not support frequency band combinations that include the first resource of the first carrier and the second resource of the second carrier.

[0013] A specific subframe can correspond to the UE's transmission link switching time.

[0014] The method may further include receiving V2X configuration information. The V2X configuration information may indicate the selection of transmission resources in the order of the first carrier and the second carrier.

[0015] The UE can select transmission resources based on the Channel Busy Rate (CBR) of the V2X signal and the ProSe Priority (PPPP) of each packet, in the order of the first carrier and the second carrier.

[0016] The first and second carriers can be configured to the UE through carrier aggregation.

[0017] In another aspect, a user equipment (UE) is provided. The UE includes a transceiver configured to transmit and receive radio signals; and a processor that operates in conjunction with the transceiver. When a specific subframe used on a second carrier, taking into account a first resource, exceeds the UE's transmission capacity, the processor selects a first resource on the first carrier, randomly selects a second resource on the second carrier from among the remaining subframes excluding the specific subframe, and uses the first and second resources to transmit V2X signals.

[0018] According to this disclosure, when carrier aggregation is used in V2X communication, transmission resources can be efficiently selected from multiple carriers by taking into account the transmission capabilities of the terminal. Attached Figure Description

[0019] Figure 1 A wireless communication system is shown.

[0020] Figure 2 This is a diagram illustrating the wireless protocol architecture used in the user plane.

[0021] Figure 3 This is a diagram illustrating the wireless protocol architecture used for the control plane.

[0022] Figure 4 The illustration shows a scenario used for V2X communication.

[0023] Figure 5 The figure illustrates an SLSS resource configuration method according to an embodiment of the present disclosure.

[0024] Figure 6 The diagram illustrates the SLSS transmission method according to this disclosure.

[0025] Figure 7 The illustration is in Figure 5 and 6 The methods described herein are applied to specific examples.

[0026] Figure 8 The illustration shows an example of resource selection for each carrier in the case of using carrier aggregation in V2X transmission (Option 1-1).

[0027] Figure 9 The diagram illustrates the resource selection method performed by the UE according to option 1-1 above.

[0028] Figure 10 The illustration shows another example (Options 1-2) of resource selection for each carrier in the case of using carrier aggregation in V2X communication.

[0029] Figure 11 The illustration shows another example (Option 2) of resource selection for each carrier in the case of using carrier aggregation in V2X communication.

[0030] Figure 12 The illustration shows an example of resource selection when CA is applied in a side link.

[0031] Figure 13 This is a block diagram of an apparatus for implementing embodiments of the present disclosure.

[0032] Figure 14 The diagram illustrates an example of a processor 1100 configuration. Detailed Implementation

[0033] Figure 1 A wireless communication system is shown.

[0034] For example, a wireless communication system can be referred to as the Evolved UMTS Terrestrial Radio Access Network (E-UTRAN) or the Long Term Evolution (LTE) / LTE-A system.

[0035] E-UTRAN includes at least one base station (BS) 20, which provides the control plane and user plane to user equipment (UE) 10. UE 10 can be fixed or mobile, and can be referred to by other terms such as mobile station (MS), user terminal (UT), subscriber station (SS), mobile terminal (MT), radio equipment, etc. BS 20 is typically a fixed station that communicates with UE 10, and can be referred to by other terms such as evolved Node B (eNB), base transceiver system (BTS), access point, etc.

[0036] BS 20 interconnects with each other via the X2 interface. BS 20 also connects to the evolved packet core (EPC) 30 via the S1 interface, and more specifically, connects to the mobility management entity (MME) via the S1-MME, and connects to the serving gateway (S-GW) via the S1-U.

[0037] EPC 30 includes an MME, an S-GW, and a Packet Data Network Gateway (P-GW). The MME holds UE access information or UE capability information, and this information is typically used for UE mobility management. The S-GW is a gateway with an E-UTRAN as its endpoint. The P-GW is a gateway with a PDN as its endpoint.

[0038] The radio interface protocol between the UE and the network can be layered based on the lower three layers of the Open Systems Interconnection (OSI) model, which is well-known in communication systems: Layer 1 (L1), Layer 2 (L2), and Layer 3 (L3). Among these, the Physical (PHY) layer, belonging to Layer 1, provides information transmission services using physical channels, while the Radio Resource Control (RRC) layer, belonging to Layer 3, controls radio resources between the UE and the network. For this purpose, the RRC layer exchanges RRC messages between the UE and the BS.

[0039] Wireless communication systems can be time division duplex (TDD) systems, frequency division duplex (FDD) systems, or systems in which TDD and FDD are used in a mixed manner.

[0040] Figure 2 This is a diagram illustrating the wireless protocol architecture used in the user plane. Figure 3 This diagram illustrates the wireless protocol architecture used for the control plane. The user plane is the protocol stack used for user data transmission. The control plane is the protocol stack used for control signal transmission.

[0041] refer to Figure 2 and3 The PHY layer provides information transmission services to the upper layers via physical channels. The PHY layer connects to the Media Access Control (MAC) layer via a transport channel, which is the layer above the PHY layer. Data is transmitted between the MAC and PHY layers via the transport channel. Transport channels are classified according to how data is transmitted via the radio interface and what characteristics of the data are transmitted.

[0042] Data moves between different PHY layers, i.e., the PHY layers of the transmitter and receiver, via the physical channel. The physical channel can be modulated according to an orthogonal frequency division multiplexing (OFDM) scheme and uses time and frequency as radio resources.

[0043] The functions of the MAC layer include mapping between logical channels and transport channels, and multiplexing / demultiplexing transport blocks provided on the physical channel via the transport channel of MAC Service Data Units (SDUs) belonging to the logical channel. The MAC layer provides services to the Radio Link Control (RLC) layer through the logical channel.

[0044] The RLC layer's functions include the cascading, splitting, and reassembling of RLC SDUs. To ensure the quality of service (QoS) of various types of services requested via radio bearers (RBs), the RLC layer provides three operating modes: Transparent Mode (TM), Non-Acknowledgment Mode (UM), and Acknowledgment Mode (AM). AM RLC provides error correction through Automatic Repeat Request (ARQ).

[0045] The RRC layer is defined only in the control plane. The RRC layer relates to the configuration, reconfiguration, and release of radio bearers, and is responsible for the control of logical channels, transport channels, and physical channels. RB refers to the logical path provided by Layer 1 (PHY layer) and Layer 2 (MAC layer, RLC layer, and PDCP layer) to facilitate data transmission between the UE and the network.

[0046] The Packet Data Convergence Protocol (PDCP) on the user plane performs functions including user data transmission, header compression, and encryption. The PDCP layer on the control plane performs functions including control plane data transmission and encryption / integrity protection.

[0047] The configuration of an RB refers to the process of defining the characteristics of the radio protocol layer and channel to provide a specific service and configuring each detailed parameter and operation method. RBs can be divided into two types: signaling RBs (SRBs) and data RBs (DRBs). SRBs are used as channels through which RRC messages are transmitted on the control plane, while DRBs are used as channels through which user data is transmitted on the user plane.

[0048] If an RRC connection is established between the UE's RRC layer and the E-UTRAN's RRC layer, the UE is in an RRC connected state. Otherwise, the UE is in an RRC idle state.

[0049] The downlink transport channels through which data is transmitted from the network to the UE include the Broadcast Channel (BCH) for transmitting system information and the Shared Downlink Channel (SCH) for transmitting user service or control messages. Service or control messages used for downlink multicast or broadcast services can be transmitted via the downlink SCH or via an additional downlink multicast channel (MCH). Meanwhile, the uplink transport channels through which data is transmitted from the UE to the network include the Random Access Channel (RACH) for transmitting initial control messages and the Shared Uplink Channel (SCH) for transmitting user service or control messages.

[0050] The logical channels placed above and mapped to the transport channel include the Broadcast Control Channel (BCCH), Paging Control Channel (PCCH), Common Control Channel (CCCH), Multicast Control Channel (MCCH), and Multicast Service Channel (MTCH).

[0051] A physical channel comprises several OFDM symbols in the time domain and several subcarriers in the frequency domain. A subframe comprises multiple OFDM symbols in the time domain. An RB (Resource Allocation Unit) is a resource allocation unit and comprises multiple OFDM symbols and multiple subcarriers. Furthermore, each subframe may use specific subcarriers of a specific OFDM symbol (e.g., the first OFDM symbol) for the corresponding subframe of the Physical Downlink Control Channel (PDCCH), i.e., the L1 / L2 control channel. The Transmission Time Interval (TTI) is a unit of time used for subframe transmission.

[0052] RRC state refers to whether the UE's RRC layer is logically connected to the E-UTRAN's RRC layer. The case where the UE's RRC layer is connected to the E-UTRAN's RRC layer is called the RRC connected state. The case where the UE's RRC layer is not logically connected to the E-UTRAN's RRC layer is called the RRC idle state. Because the UE has an RRC connection, the E-UTRAN can check the presence of the corresponding UE in the RRC connected state, and therefore, the UE can be effectively controlled. Conversely, the E-UTRAN cannot check UEs in the RRC idle state, and the core network (CN) manages UEs in the RRC idle state in each tracking area, i.e., a unit of area larger than the cell. That is, the presence or absence of UEs in the RRC idle state is only checked for each large area. Therefore, the UE needs to transition to the RRC connected state to be provided with public mobile communication services such as voice or data.

[0053] When a user first powers on the UE, the UE first searches for a suitable cell and remains in RRC idle state within that cell. When it is necessary to establish an RRC connection, the UE in RRC idle state establishes an RRC connection with the E-UTRAN through the RRC connection procedure and is transitioned to RRC connected state. There are several situations in which a UE in RRC idle state needs to establish an RRC connection. For example, situations may include the need to send uplink data due to reasons such as a user's call attempt, and the need to send response messages to paging messages received from the E-UTRAN.

[0054] The Non-Access Layer (NAS), located above the RRC layer, performs functions such as session management and mobility management.

[0055] In the NAS layer, two types of states are defined for managing UE mobility: EPS Mobility Management - Registered (EMM-REGISTERED) and EMM-Deregistered (EMM-DEREGISTERED). These two states apply to both the UE and the MME. The UE is initially in the EMM-DEREGISTERED state. To access the network, the UE performs an initial attachment procedure to register with the appropriate network. If the attachment procedure is successfully executed, the UE and MME transition to the EMM-REGISTERED state.

[0056] To manage the signaling connection between the UE and EPC, two types of states are defined: EPS Connection Management (ECM)-IDLE (ECM-Idle) state and ECM-CONNECTED (ECM-Connected). These two states are applied to both the UE and the MME. When a UE in ECM-IDLE state establishes an RRC connection with the E-UTRAN, the UE enters the ECM-CONNECTED state. When it establishes an S1 connection with the E-UTRAN, the MME in ECM-IDLE state enters the ECM-CONNECTED state. When the UE is in ECM-IDLE state, the E-UTRAN does not have background information about the UE. Therefore, a UE in ECM-IDLE state performs UE mobility-related procedures, such as cell selection or cell reselection, without needing to receive commands from the network. Conversely, when the UE is in ECM-CONNECTED state, it manages UE mobility in response to commands from the network. If the location of a UE in ECM-IDLE state is different from the location known to the network, the UE will notify the network of the corresponding location through the tracking area update process.

[0057] D2D operations will now be described. In 3GPP LTE-A, the service associated with D2D operations is called Pro-Se (Pro-Neighborhood Service). In the following text, ProSe is equivalent to D2D operations, and the two operations are interchangeable. ProSe will now be described.

[0058] ProSe includes ProSe directional communication and ProSe direct discovery. ProSe direct communication is communication performed between two or more nearest neighbor UEs. UEs can perform this communication using user plane protocols. A ProSe-enabled UE implies a UE that supports procedures related to ProSe requirements. Unless otherwise specified, a ProSe-enabled UE includes both public safety UEs and non-public safety UEs. A public safety UE is a UE that supports both the public safety-specified features and the ProSe procedures, while a non-public safety UE is a UE that supports the ProSe procedures but does not support the public safety-specified features.

[0059] ProSe direct discovery is the process for discovering another ProSe-enabled UE that is adjacent to a ProSe-enabled UE. In this case, only the capabilities of both types of ProSe-enabled UEs are used. EPC-level ProSe discovery refers to the process by which the EPC determines whether two types of ProSe-enabled UEs are adjacent and notifies both types of ProSe-enabled UEs of this proximity.

[0060] In the following text, for convenience, ProSe direct communication may be referred to as D2D communication, and ProSe direct discovery may be referred to as D2D discovery. The link used for D2D operation is called a side link in LTE.

[0061] Now, let's describe vehicle-to-everything (V2X) communication. V2X refers to communication between a UE installed in a vehicle and another UE, which can correspond to a pedestrian, vehicle, or infrastructure. In this context, these can be referred to as vehicle-to-pedestrian (V2P), vehicle-to-vehicle (V2V), and vehicle-to-infrastructure (V2I), respectively.

[0062] V2X communication sends / receives data / control information via a sidelink defined in D2D operations, rather than via an uplink / downlink between the eNB and UE used in traditional LTE communication.

[0063] The following physical channels can be defined in the side link as follows.

[0064] The Physical Sidelink Broadcast Channel (PSBCH) is a physical sidelink broadcast channel. The Physical Sidelink Control Channel (PSCCH) is a physical sidelink control channel. The Physical Sidelink Discovery Channel is a physical sidelink discovery channel. The Physical Sidelink Shared Channel is a physical sidelink shared channel. The Sidelink Synchronization Signal (SLSS) is a sidelink synchronization signal. The SLSS can include the Primary Sidelink Synchronization Signal (PSSS) and the Secondary Sidelink Synchronization Signal (SSSS). The SLSS and PSBCH can be transmitted together.

[0065] Side link can refer to the interface between UEs, and side link can correspond to PC5 interface.

[0066] Figure 4 The illustration shows a scenario used for V2X communication.

[0067] refer to Figure 4 (a) V2X communication can support PC5-based information exchange operations (between UEs), where PC5 is the interface between UEs, and as shown in Figure 4(b), it can also support Uu-based information exchange operations (between UEs), where Uu is the interface between the eNodeB and the UE. Additionally, as... Figure 4 As shown in (c), information exchange operations (between UEs) can be supported by using both PC5 and Uu.

[0068] In the following description, for ease of description, this disclosure is based on 3GPP LTE / LTE-A systems. However, the scope of the systems to which this disclosure applies can be extended to other systems besides 3GPP LTE / LTE-A systems.

[0069] Now, this disclosure will be described.

[0070] The following technical proposal proposes a method for a UE that does not have the ability to perform simultaneous transmission and / or reception (or a UE with limitations on the ability to perform simultaneous transmission and / or reception, and hereinafter, such a UE is referred to as "LCAP_UE") to efficiently perform V2X communication on multiple (V2X) carriers configured ( / notified by signaling) in carrier aggregation (CA) technology.

[0071] The technical proposals disclosed herein (part of the proposals) can be applied in a limited manner in the case of "continuous or non-continuous CA in intra-band".

[0072] V2X communication modes include (A) mode (referred to as mode #3), in which the eNB signals ( / controls) scheduling information related to V2X message transmission ( / reception) (on a V2X resource pool pre-configured ( / notified by signaling) from the eNB ( / network)) (representatively). For example, in mode 3, the UE located within the eNB's communication coverage area (and / or in the RRC_CONNECTED state) is the primary target. And / or V2X communication modes include (B) mode (referred to as mode #4), in which the UE independently determines ( / controls) scheduling information related to V2X message transmission ( / reception) (on a V2X resource pool pre-configured ( / notified by signaling) from the eNB ( / network). For example, in mode 3, the UE located within / outside the eNB's communication coverage area (and / / or in the RRC_CONNECTED / RRC_IDEL state) can be the primary target.

[0073] In this disclosure, "sensing operation" can be interpreted as a PSSCH-RSRP measurement operation based on a PSSCH DM-RS sequence, which is scheduled by a PSCCH that has been successfully decoded therein, and / or an S-RSSI measurement operation based on a sub-channel associated with a V2X resource pool.

[0074] In this disclosure, "receive" can be interpreted broadly as at least one of the following:

[0075] (A) V2X channel ( / signal) (e.g., PSCCH, PSSCH, PSBCH, PSSS / SSSS, etc.) decoding ( / receive) operations (and / or WAN DL channel ( / signal) (e.g., PDCCH, PDSCH, PSS / SSS, etc.) decoding ( / receive) operations,

[0076] (B) Sensing operation, and

[0077] (C) CBR measurement operation.

[0078] In this disclosure, “transmission” can be interpreted broadly as V2X channel ( / signal) transmission operations (e.g., PSCCH, PSSCH, PSBCH, PSSS / SSSS, etc.) (and / or WAN UL channel ( / signal) transmission operations (e.g., PUSCH, PUCCH, SRS, etc.)).

[0079] In this disclosure, "carrier" can be interpreted broadly as at least one of (A) a pre-configured ( / signaled) set ( / group) of carriers, (B) a V2X resource pool (set ( / group)) and (C) a set / group of time / frequency resources on a carrier.

[0080] The technical proposals of this disclosure (part of the proposals) can be extended to V2X communication of UEs (e.g., UEs with simultaneous transmit and / or receive capabilities on multiple (V2X) carriers pre-configured ( / notified by signaling) by a CA, whose capabilities are relatively superior to LCAP_UE).

[0081] In this disclosure, "synchronization signal" can be extended to include both "PSBCH" and "SLSS". In this disclosure, "LCAP_UE" can be extended to include at least one of a UE with "limited transmit (link) capability" and a UE with "limited receive (link) capability".

[0082] The description will include the sidelink received signal strength indicator (S-RSSI), the sidelink reference received signal power (S-RSRP), the channel busy ratio (CBR), and the channel occupancy ratio (CR).

[0083] First, S-RSSI is an indicator of received signal strength in the side link. S-RSSI can be defined as the linear average of the total received power of each SC-FDMA symbol in the first time slot (SC-FDMA symbols #1, 2, ..., 6) and the subframe (SC-FDMA symbols #0, 1, ..., 5), which is observed by the UE in the configured sub-channel.

[0084] S-RSRP refers to the received power of the reference signal in the sidelink. In S-RSRP, for example, there is a PSSCH-RSRP that calculates the RSRP in the PSSCH. PSSCH-RSRP can be defined as the linear average of the power contributions of resource elements (REs) carrying the demodulated reference signal (DM-RS) associated with the PSSCH in the physical resource block (PRB) indicated by the associated PSCCH.

[0085] CBR indicates the busy rate of the channel, and the CBR measured in subframe n can be defined as follows.

[0086] The PSSCH is sensed in subframe [n-100, n-1], and it indicates the ratio in the resource pool of the subchannel with S-RSSI, which is measured to exceed a predefined or pre-configured threshold.

[0087] The PSCCH is sensed in subframes [n-100, n-1] and indicates the ratio of resources in a pool of PSCCHs with S-RSSI that are configured to be transmitted together with the corresponding PSSCHs in non-contiguous resource blocks. S-RSSI is measured as exceeding a predefined or pre-configured threshold. Here, it is assumed that the PSCCH pool comprises resources the size of two consecutive PRB pairs in the frequency domain.

[0088] CR stands for Channel Occupancy Rate. The CR calculated in subframe n can be defined as the sum of the number of subchannels used for its own transmission in subframe [na, n-1] and the number of subchannels allowed for its own transmission in subframe [n, n+b], divided by the number of subchannels configured in the transmission pool throughout subframe [na, n+b].

[0089] Here, "a" is a positive integer, and b is 0 or a positive integer. "a" and "b" are determined by the UE. The relationship between "a" and "b" is a+b+1=1000, where a is 500 or greater, and n+b should not exceed the latest permitted transmission time for the current transmission.

[0090] [Proposed Method #1] Among multiple V2X carriers configured (or signaled) by CA, the LCAP_UE may preferentially perform transmit (and / or receive) operations on a carrier selected according to a portion of the pre-configured (or signaled) priority information (or rules).

[0091] (Rule #1-1) (A) Transmit (and / receive) carriers associated with a specific service (and / or data ( / message ( / application type))) that are pre-configured ( / signaled); and / or (B) carriers on which V2X message transmission (and / or reception) operations are performed based on PPPP (and / or (remaining) delay requirements), and / or message generation ( / transmit (receive)) periods that are larger (or smaller) (and / relatively larger (or smaller) than a pre-configured ( / signaled) threshold, and / or resource reservation intervals ( / periods); and / or (C) transmit (and / receive) carriers; and / or (D) carriers on which synchronization signal transmission (and / receive) is configured ( / signaled) (and / or synchronization reference carriers associated with V2X transmission (and / receive) on other carriers) and / or (E) (specific) synchronization source type (SYNCH) pre-configured ( / signaled). (SOURCETYPE) A carrier with (relative) higher priority; and / or (F) a scheduled (and / or scheduled) carrier in the case of cross-carrier scheduling (CCS) configured (or signaled); and / or (G) a transmit (and / receive) carrier with a CBR ( / CR) measurement (and / or (remaining) CR_LIMIT and / or (maximum) (allowed) transmission power) that is larger (or smaller) (and / relatively larger (or smaller) than the pre-configured (or signaled) threshold; and / or (H) a carrier with a higher (or lower) priority pre-configured (or signaled); and / or (I) a shared carrier (with WAN (uplink) communication).

[0092] (Rule #1-2) In (Rule #1-1), at least one piece of information about the (representative) CBR, CR, (residual) CR_LIMIT and (maximum allowed) transmission power of a carrier used as a carrier (priority) selection criterion can be derived ( / defined) as a (weighted) average or maximum ( / minimum) value of (measurement / configuration) values ​​of multiple (transmit / receive) resource pools on the carrier.

[0093] As another example, after selecting a carrier based on the above (priority) rules, the above criteria ( / priority parameters) can be (re)applied to the selection of the (transmit / receive) pool that will actually be used for V2X message transmission ( / reception) among the multiple (transmit / receive) resource pools on the selected corresponding carrier.

[0094] [Proposed Method #2] For each carrier, at least one of the resource location ( / mode), period, and subframe offset information that prioritizes transmission (and / or reception) operations compared to other carriers can be pre-configured or signaled.

[0095] As an example, when the LCAP_UE performs at least one of (A) (transmission) resource reservation ( / selection) operation, (B) sensing operation (e.g., S-RSSI measurement, PSSCH-RSRP measurement), and (C) CBR measurement operation, the corresponding configuration ( / signaling) may be used preferentially only.

[0096] For another example, since synchronization signal transmission (and / or reception) operations are relatively important for maintaining V2X communication performance, resources on carrier #Y that (partially) overlap with synchronization signal transmission (and / or reception) resources on carrier #X may not perform sensing operations and / or CBR measurement operations and / or (transmission) resource reservation ( / selection) operations and / or V2X message ( / channel / signal) transmission ( / reception).

[0097] As an example, by (pre-)allocating (or signaling) a specific (virtual) PPPP (P_SYN), PPPP that is relatively lower than P_SYN can be omitted during the protection of the corresponding synchronization signal reception ( / transmission) (e.g., V2X message ( / channel / signal) reception ( / transmission) that (partially) overlaps with the synchronization signal reception ( / transmission) resources).

[0098] For another example, to mitigate the reduction in synchronization signal transmission power, in resources on carrier #Y that partially overlap with synchronization signal transmission resources on carrier #X, (A) transmission operations related to a specific service (and / or data ( / message ( / application) type) pre-configured ( / signaled); and / or (B) PPPPs greater than (or less than) a pre-configured ( / signaled) threshold (e.g., it can be interpreted that a (virtual) PPP (or a specific (virtual) PPPP) with a (corresponding) pre-configured ( / signaled) threshold can be performed ( / permitted), and / or V2X message transmission operations based on (remaining) delay requirements and / or message generation ( / transmission ( / reception)) cycles and / or resource reservation intervals ( / cycles) can only be performed ( / permitted).

[0099] [Proposed Method #3] When performing V2X message transmission operation at the timing of subframe (SF) #K of carrier #A based on the above [Proposed Method #1] and / or [Proposed Method #2], and when it cannot monitor (and / or sense) the SF #P of carrier #B that overlaps (partially or entirely) with the corresponding subframe (i.e., SF #K of carrier A) in the time domain, when reserving ( / selecting) V2X communication-related (transmission) resources on carrier #B, the LCAP_UE can exclude (all) candidate (transmission) resources (in the selection window) that overlap (or conflict) with the following resources, which are separated from SF #P by one (candidate) resource reservation period (and / / or pre-configured ( / signaled) count).

[0100] [Proposed Method #4] By synchronizing the following (partial) parameters ( / configuration) among multiple carriers pre-configured ( / notified by signaling), the LCAP_UE (or UE) can efficiently perform V2X communication on multiple (V2X) carriers configured ( / notified by signaling) by the CA.

[0101] (Rule #4-1) The location and / or number of transmission (and / or reception) resources for synchronization signals (SLSS) (and / or the location and / or number of subframes (and / or the size and / or number of subchannels) associated with the V2X resource pool) can be synchronized across multiple carriers.

[0102] With the application of rules, logical (subframe) indices (and / or DFNs) (and / or V2X resource pools) related to V2X communication can be synchronized across multiple carriers (based on the anchor carrier or the synchronized carrier), thereby efficiently resolving the problem of not being able to perform simultaneous transmission and / or reception on multiple (V2X) carriers configured (or signaled) by the CA. In other words, simultaneous transmission (or reception) operations can be efficiently scheduled (or executed) across multiple carriers.

[0103] Figure 5 The figure illustrates an SLSS resource configuration method according to an embodiment of the present disclosure.

[0104] refer to Figure 5 For V2X communication, three carriers (carriers #1, #2 and #3) can be configured for the UE through carrier aggregation.

[0105] In this scenario, the number and location of SLSS resources can be configured identically across multiple carriers. For example... Figure 5 As shown, the number and location of configured SLSS resources are the same in carriers #1, #2, and #3. This configuration is designed to ensure that the (sidelink) logical (subframe) index (and / or direct frame number (DFN)) related to V2X communication is set to the same value in carriers #1, #2, and #3. That is, frames that overlap in the time domain in carriers #1, #2, and #3 can have the same (sidelink) logical (subframe) index (and / or DFN) value.

[0106] From the UE's perspective, the UE can assume that the location and quantity of SLSS resources are the same across all carriers aggregated for V2X communication.

[0107] As an example, you can (limitedly) configure ( / signal) carriers (pairs) with the same parameters ( / configuration) as the above (and / or configure ( / signal) carriers (pairs) with cross-carrier scheduling and / or carriers (pairs) with the same (time / frequency) synchronization reference carriers: (A) transmit and / or receive carriers with the same service (and / or data ( / message ( / application)) type as (specific) (pre-configured ( / signal)); and / or (B) carriers with the same synchronization source type as (specific) (pre-configured ( / signal)) and having (relatively) higher priority. Transmit and / or receive) carriers; and / or (C) carriers (pairs) configured to ( / signal) the CCS and / or carriers (pairs) wherein the (time / frequency) synchronization difference is less than a pre-configured ( / signal) threshold and / or carriers (transmit and / or receive) carriers having the same (time / frequency) synchronization reference carrier as (specific) (pre-configured ( / signal)).

[0108] (Rule #4-2) As an example, in the case where the same (time / frequency) synchronization reference carrier is configured ( / signal notification) (this is referred to as a carrier that is not a synchronization reference carrier and is called a non-synchronization reference carrier (NON-SYNRFCC)), in order to support V2X communication of existing (legacy) UEs (e.g., UEs operating in accordance with LTE REL-14) on the (corresponding) carrier that is not a synchronization reference carrier (NON-SYNRFCC), the synchronization resource can be configured ( / signal notification).

[0109] As another example, synchronization resource configuration ( / signaling) on ​​a (corresponding) carrier that is not a synchronous reference carrier (asynchronous reference carrier; NON-SYNRFCC) can be performed for the purpose of synchronizing (side-link) logical (subframe) indexes (and / or DFNs) between synchronous and asynchronous reference carriers. For this purpose, the location ( / number) of synchronization resources configured ( / signaled) on the asynchronous reference carrier can be the same as the location ( / number) of synchronization resources on the synchronous reference carrier. Alternatively, synchronization resources configured ( / signaled) on the asynchronous reference carrier can be implemented only when synchronization resources are configured ( / signaled) on the synchronous reference carrier.

[0110] As an example, in the case of an improved UE (a UE operating according to LTE REL-15), depending on the network configuration ( / signaling), the transmission of synchronization signals (e.g., SLSS) can be performed on synchronization resources on asynchronous reference carriers (NON-SYNRFCC) (and synchronous reference carriers). In this case, even when synchronization resources are configured on asynchronous reference carriers (and / or synchronous reference carriers), it can be interpreted that the network (ultimately) instructs ( / controls) whether to transmit the actual synchronization signal for the improved UE. For example, when synchronization resources are configured on synchronous reference carriers, SLSS can be always transmitted by using the synchronization resources. Conversely, even when synchronization resources are configured on asynchronous reference carriers, the network can control whether to actually transmit the synchronization signal.

[0111] The asynchronous reference carrier configured above ( / signal notification) (same) (time / frequency) synchronization reference carrier can be limited to the same synchronization source type and has (relatively) higher priority (transmit and / or receive) carriers compared to the synchronization reference carrier.

[0112] Figure 6 The diagram illustrates the SLSS transmission method according to this disclosure.

[0113] refer to Figure 6 The UE receives SLSS resource configuration information; however, the SLSS resource configuration information can configure the same location and number of SLSS resources in each of the multiple carriers aggregated by the carriers (step S210). See above reference... Figure 5 The reason described for configuring the same position and number of SLSS resources in each of the multiple carriers configured through carrier aggregation may be to synchronize the (side link) logical (subframe) indexes (and / or DFNs) across the multiple carriers.

[0114] The UE receives SLSS transmission configuration information indicating whether to actually transmit synchronization signals (e.g., PSSS / SSSS) using SLSS resources (step S220). More specifically, the network may instruct the UE whether to actually perform SLSS transmission operations only in the corresponding SLSS resources in non-synchronous reference carriers (e.g., a carrier that is not a synchronous reference carrier among multiple carriers (NON-SYNRFCC)).

[0115] The UE can transmit synchronization signals (e.g., PSSS / SSSS) using SLSS resources indicated by SLSS resource configuration information in the asynchronous reference carrier based on SLSS transmission configuration information (step S230). Of course, this only operates if the UE is configured to transmit synchronization signals in the asynchronous reference carrier based on SLSS transmission configuration information.

[0116] SLSS resource configuration information and SLSS transport configuration information can be received either by including them in the same message or by including them in separate messages.

[0117] Figure 7 Illustration Figure 5 and Figure 6 The methods described herein are applied to specific examples.

[0118] refer to Figure 7 The network sends SLSS resource configuration information to UE #1 (step S310). The SLSS resource configuration information can set SLSS resources for carriers #1, #2, and #3 that are carriers aggregated. Here, it is assumed that carriers #2 and #3 are asynchronous reference carriers. It is assumed that carrier #1 is a synchronous reference carrier. As described above, the same number and location of SLSS resources can be set in multiple carriers #1, #2, and #3 that are carriers aggregated.

[0119] The network sends SLSS transmission configuration information to UE #1 (step S320). In this case, the SLSS transmission configuration information may indicate or notify that SLSS is not actually transmitted for carriers #2 and #3. That is, the UE may be configured with the location of SLSS resources for carriers #2 and #3 as asynchronous reference carriers, but may be configured not to transmit SLSS.

[0120] Despite Figure 7 Not shown, but in the case where the network configures the transmission of SLSS configuration information between carrier #2 and carrier #3, which are asynchronous reference carriers, to actually transmit SLSS in carrier #2 but not actually transmit SLSS in carrier #3, the UE may actually transmit SLSS in carrier #2, but may not actually transmit SLSS in carrier #3.

[0121] UE #1 can send an SLSS to UE #2 via carrier #1 (step S330). Carrier #1 is a synchronization reference carrier, and SLSS can always be sent on carrier #1 when synchronization resources are set. Alternatively, even when carrier #1 is a synchronization reference carrier, the network can be configured to not actually send an SLSS. In this case, the SLSS transmission configuration information may include information indicating whether to actually send an SLSS even for carrier #1, which is the synchronization reference carrier.

[0122] [Proposed Method #5] When there are reserved (or selected) (transmission) resources (e.g., mode ( / location / quantity), period ( / subframe offset) etc.) on carrier #X (in advance or previously), when reserving (or selecting) (transmission) resources related to carrier #Y, LCAP_UE may preferentially (or to a limited extent) consider (or select) (only) (in the time domain) (partial) resources that overlap with the reserved (or selected) (transmission) resources on (corresponding) carrier #X.

[0123] As an example, the maximum number of resources that can be selected on the same TTI across multiple carriers can be no greater than the UE's transmission capacity (TX capacity), such as the number of supported transmission chains, and / or can be limited to the number that does not trigger a power-limiting condition. A power-limiting condition can refer to a situation where, with V2X message transmissions on multiple carriers partially or completely overlapping in the time domain, the sum of the V2X message transmission power calculated for each carrier exceeds the UE's maximum transmission power (maximum TX power, e.g., 23 dBm).

[0124] In other words, when selecting resources for a specific carrier (e.g., carrier #Z), the UE can exclude the TTIs on which the corresponding maximum number of resource selections has been completed and (randomly) select resources on the remaining TTIs. Then, resource selection for other carriers can be performed on the corresponding selected TTIs until the maximum allowed number is reached.

[0125] [Proposed Method #6] The CBR ( / CR) (and / or remaining transmission / resource usage opportunities and / or sensing compared with CR_LIMIT) measurement on the pre-configured ( / signaled) carrier #X can be extended to other carriers (including carrier #X) configured ( / signaled) by CA.

[0126] As an example, when applying the (corresponding) CBR ( / CR) (and / or remaining transmission / resource usage opportunities and / or sensing) measurements compared with CR_LIMIT in an extended manner, different (weighted) ratio ( / partial) values ​​can be considered for each different carrier.

[0127] As another example, in cases where the location and / or quantity of synchronization signal (send (and / or receive)) resources are configured (partially) differently between different carriers configured ( / signaled) by the CA, the logical index ( / DFN) (related to V2X communication) can be synchronized between multiple carriers by applying the following rules.

[0128] [Proposed Method #7] As an example, when resources on carrier #Y (or carrier #X) that partially overlap with the resource locations of the synchronization signals in carrier #Y (or carrier #X) are allocated together with the (actual) synchronization signal resources associated with carrier #Y (or carrier #X) by assuming ( / treating) resources as (virtual) synchronization signal resources additionally configured ( / signaled) to carrier #Y (or carrier #X) or by configuring ( / signaling) the "reserved subframes" associated with carrier #Y (or carrier #X) (e.g., this may mean resources that have not been allocated with V2X pool logical index ( / DFN)) associated with carrier #Y (or carrier #X), resources on carrier #Y (or carrier #X) that partially overlap with the resource locations of the synchronization signals in carrier #Y (or carrier #X) can be excluded.

[0129] As another example, when performing cross-carrier scheduling (CCS), in order to minimize (to the maximum) the time ( / frequency) synchronization difference between the scheduled carrier #X and the scheduled carrier #Y, cross-carrier scheduling operations can be performed (to a limited extent) between V2X resource pools where transmissions ( / receives) based on the same synchronization source type are permitted for different carriers.

[0130] As an example, in the case of transmitting CCS control ( / scheduling) information in subframe #N of a V2X resource pool where transmission based on synchronization source type #A is permitted, (interlinked) data transmission can be performed in the nearest subframe of the V2X resource pool where transmission based on synchronization source type #A is permitted on carrier #Y 4 ms (4 subframes) after the time of subframe #N.

[0131] For CA, the following scenarios are supported.

[0132] 1) Parallel transmission of MAC PDUs. Here, "parallel transmission" means transmission on different carriers that are simultaneous at different timings. In this case, the payloads of the MAC PDUs can be different from each other. 2) Parallel transmission of copies of the same packets. 3) Improved receiver capabilities. In terms of the receiver, simultaneous reception on multiple carriers can be assumed. In terms of the transmitter, transmission can occur via carriers corresponding to a subset of the available carriers. The UE can support operation of transmitting via a single carrier and also support operation of receiving via multiple carriers.

[0133] The PSCCH and associated PSSCH can be transmitted over the same carrier. However, this does not mean that the PSCCH may include information from other carriers.

[0134] In the case of the UE, when the synchronization source is selected independently in different carriers, the synchronization signal subframes can be different in the carriers. Therefore, the DFN number, subframe boundary, etc. can also become different in the carriers.

[0135] When subframe boundaries are the same but DFN numbers are different, the location of resources that should be semi-statically delayed in the carrier can be gradually shifted. Then, simultaneous transmissions occur in one subframe and separate transmissions occur in other subframes, thus potentially causing fluctuations in transmission power. When transmission power fluctuates, sensing operations at the receiver may become unstable.

[0136] Furthermore, when the subframe boundaries differ between carriers, it is difficult to fully utilize the transmission power.

[0137] In summary: 1) From the UE's perspective, when independent synchronization sources are selected between carriers, the synchronization signal subframes within the carriers can become different, resulting in different DFN numbers and subframe boundaries within the carriers. 2) When DFN numbers are not assigned, even if the UE blocks resource sets within the carrier, the positions of resources that should be semi-statically delayed within the carrier can be offset. 3) When subframe boundaries become different, it is difficult to fully utilize transmission power.

[0138] To prevent problems, it may be necessary to determine the sidelink synchronization anchor carrier. The sidelink synchronization anchor carrier can also be represented as the synchronization reference carrier described above.

[0139] For a set of sidelink component carriers (CCs), a common synchronization source priority configuration can be used. PSCCH / PSSCH transmissions on any sidelink CC in the set can be performed based on the synchronization reference selected for the sidelink synchronization anchor carrier, and SLSS / PSBCH should be performed based on the synchronization reference of the sidelink synchronization anchor carrier.

[0140] When a UE selects a synchronization source in the sidelink synchronization anchor carrier, the synchronization process for an existing UE requires that the same SLSS / PSBCH be transmitted to all CCs in the sidelink CC group.

[0141] In cases where only UEs operate via LTE-Rel-15 exist, for power efficiency, SLSS / PSBCH can be transmitted only on the sidelink synchronization anchor carrier. Multiple sidelink synchronization anchor carriers can exist in different service or local boundaries.

[0142] The number of asynchronous CCs sent / received simultaneously can depend on the UE's capabilities.

[0143] <Proposal 1> Definition of Sidelink Synchronization Anchor Carrier

[0144] For a group of sidelink CCs, a common synchronization source priority configuration can be used. The synchronization reference selected for the sidelink synchronization anchor carrier can be used for PSCCH / PSSCH transmissions on any CC in the group. SLSS / PSBCH transmissions should be sent based on the synchronization reference selected in the sidelink synchronization anchor carrier. For a group of sidelink CCs, subframe boundaries and DFN numbers can be aligned.

[0145] As another example, when its actual transmission (chain) capacity is less than the number of transmission carriers (TX carriers) selected at a higher layer (e.g., the application layer) (e.g., the UE can be interpreted as a UE with limited transmission capacity), the UE can select (or signal) specific carriers (e.g., anchor carrier, synchronization reference carrier, highest priority carrier, etc.) that are pre-configured (or signaled) for transmission using synchronization signals. And / or, the UE can randomly select from the transmission carriers selected at the higher layer (e.g., the application layer), and / or can select the transmission carriers selected at the higher layer (e.g., the application layer) by interleaving them in the time domain according to predefined rules. And / or the UE can select carriers on which no existing UE (legacy UE) exists and / or exclude carriers on which only advanced UEs (UEs operating according to LTE REL-15) are allowed to serve and select the remaining carriers.

[0146] As another example, in cases where V2X message transmissions partially or completely overlap in the time domain on multiple carriers and / or the sum of the V2X message transmission power calculated for each carrier exceeds the UE's maximum transmission power (maximum TX power, e.g., 23 dBm) (this situation is referred to as the power-limited situation), the UE may omit V2X message transmissions on a portion of the carriers and / or reduce the power of the V2X message transmissions.

[0147] (Example #1) V2X message transmissions at relatively low (or lower than the pre-configured ( / signaled) threshold) PPPP (and / or service priority and / or carrier priority) (or relatively high ( / low) (or higher than the pre-configured ( / signaled) threshold) CBR ( / CR) levels (and / or remaining transmission / resource usage opportunities compared to CR_LIMIT) are omitted (and / / transmission power is reduced), but corresponding transmission omission operations (and / / transmission power reduction operations) can be applied until the power limitation is mitigated.

[0148] As a specific example, assume that the V2X message PPPP values ​​on carriers #1 / 2 / 3 are PPPP #A / B / C respectively, and the priority among the corresponding PPPPs is A>B>C. If the UE can escape the power limitation situation when V2X message transmission on carrier #3 with the lowest PPPP value is omitted (and / or its power is reduced) but V2X message transmission on carrier #2 is not omitted (and / or its power is reduced), V2X message transmission on the remaining carriers #1 / 2 can be maintained.

[0149] (Example #2) In the case of applying Example #1, and where a portion of a V2X message transmission with the same priority (e.g., in cases where PPPP, service priority, carrier priority, carrier CBR ( / CR) level, remaining transmission / resource usage opportunities compared to CR_LIMIT, and resource PSSCH-RSRP ( / S-RSSI) are the same) should be omitted (and / or transmission power should be reduced) to escape the power-limited situation, (A) the UE may randomly select V2X messages to omit (and / or reduce transmission power). And / or (B) the UE may omit V2X messages (and / or reduce transmission power) on carriers with relatively high ( / low) (or higher ( / lower) CBR ( / CR) (and / / or remaining transmission / resource usage opportunities compared to CR_LIMIT) values ​​than the pre-configured ( / signaled) threshold. And / or (C) the UE may prioritize non-periodic (or periodic) message transmissions over periodic (or periodic) message transmissions (and / or reduce transmission power), and / or (D) the UE may exceptionally perform (all) transmissions without omission (and / or reduction of transmission power).

[0150] (Example #3) It is possible to pre-configure (or signal) count information from the network (or eNB) to continuously omit (and / reduce) the available counts of transmissions for each priority level (e.g., PPPP, service priority, carrier priority, carrier CBR ( / CR) level, remaining transmission / resource usage opportunities compared to CR_LIMIT, resource PSSCH-RSRP ( / S-RSSI)). By applying appropriate rules, the problem of excessive omission (or excessive reduction) of relatively low-priority V2X message transmissions can be mitigated.

[0151] As another example, the following (partial or complete) rules can be used to avoid (excessive) overlap of resource (re)selection on multiple carriers (and / or can (simultaneously) mitigate the half-duplex problem).

[0152] The corresponding rules can be applied in a limited way to (A) cases where the UE should transmit V2X messages on carriers configured ( / signaled) by a higher layer with a capacity relatively greater than its own transmission (chain) capacity (and / or in cases where the transmission chain switching time (between different carriers) is ensured and resource selection is performed in consideration), (B) cases where power limiting is avoided, and (C) cases where half-duplex issues related to in-band CA are mitigated, etc.

[0153] The carrier-specific resource selection in this disclosure can be performed only in a limited or additional manner within a set of selectable transmission candidate resources determined by sensing operations (e.g., excluding high-interference resources).

[0154] (Example #1) Basically, resource (re)selection for each carrier is performed randomly (or independently) in a pre-configured ( / signaled) order. However, after the number of overlapping carrier resources (this is called NUM_OV) for which a previously completed TTI is selected is counted, the corresponding TTI can be excluded from the resource selection for the corresponding specific carrier if the NUM_OV on the TTI meets a predefined condition, and the corresponding TTI is randomly selected from the resources on the remaining TTIs.

[0155] The UE can also randomly select resources on TTIs with relatively small (or large) NUM_OV values ​​from among the remaining TTIs (one or more) that have not been excluded.

[0156] The conditions can be defined as follows. Here, for example, when resources are (re)selected on a particular carrier, K TTIs (e.g., K = 1) before and / or after the resources of (one or more) carriers (one or more) that were previously selected can be additionally excluded (e.g., for transmission link switching time).

[0157] (1) When NUM_OV is the same as the UE's transmission capability (e.g., the number of supported transmission chains).

[0158] (2) The remainder of the transmission power budget (TX power budget) limit (or the UE’s maximum transmission power) minus the sum of the transmission power related to NUM_OV cannot allow simultaneous (on the corresponding TTI) transmission without causing a power limit situation.

[0159] Figure 8 The illustration shows an example of resource selection for each carrier in the case of using carrier aggregation in V2X transmission (Option 1-1).

[0160] refer to Figure 8Assume that carriers #1, #2, and #3 are configured to the UE via carrier aggregation for V2X communication, and that the UE is a UE with only two transmission chains. That is, assume that the UE has the capability to transmit V2X signals to only two carriers simultaneously.

[0161] In this scenario, the UE can exclude a subset of resources (e.g., subframes) from the candidate resource selection for V2X communication during the sensing process of each carrier. For example, the UE can exclude resources whose PSSCH-RSRP measurement is greater than a pre-configured threshold or whose S-RSSI measurement is relatively high, even if the resource is reserved by other UEs. Figure 8 An example is the case where resources (e.g., subframes) are excluded during the following process: during sensing, subframes 1 and 2 are excluded on carrier #1, subframes 1, 3, 4 and 7 are excluded on carrier #2, and subframes 2 and 5 are excluded on carrier #3.

[0162] The UE can select resources for V2X communication for each carrier based on a predefined carrier order or a configured carrier order (e.g., the UE can receive V2X configuration information, which may indicate the selection of transmission resources in the order of the first and second carriers). In this case, the carrier resource selection order can be defined by considering the ProSe priority (PPPP), CBR, etc. of each packet. For example, suppose the UE selects resources for V2X communication in the order of carriers #1, #2, and #3.

[0163] First, assume the UE selects subframes 3 and 6 from among the subframes that were not excluded during the sensing process on carrier #1 (e.g., randomly). Next, on carrier #2, the UE selects resources for V2X communication from among the subframes that were not excluded during the sensing process, and in this case, the UE considers the resources selected for V2X communication on the carrier (i.e., carrier #1) where resource selection was previously completed. For example, since selecting subframe 6 on carrier #2 would not exceed the UE's transmission capacity (i.e., simultaneous transmission on both carriers), the UE selects subframe 6 on carrier #2. Similarly, the UE could also select subframe 2 on carrier #2.

[0164] Next, the UE selects resources for V2X communication in carrier #3 that were not excluded during the sensing process, and the UE considers the resources selected for V2X communication in the carriers where resource selection was previously completed, namely carrier #1 and carrier #2. For example, because selecting subframe 6 of carrier #3 exceeds the UE's transmission capacity (i.e., it can transmit on two carriers simultaneously), the UE selects resources for V2X communication in the remaining subframes other than subframe 6 of carrier #3. Because even selecting subframe 3 of carrier #3 would not exceed the UE's transmission capacity (i.e., it can transmit on two carriers simultaneously), the UE selects subframe 3 of carrier #3. Similarly, the UE can also select subframe 7 of carrier #3.

[0165] Figure 9 The diagram illustrates the resource selection method performed by the UE according to option 1-1 above.

[0166] refer to Figure 9 The UE selects a transmission resource (first resource) on the first carrier (step S410). If the use of a specific subframe on the second carrier exceeds the UE's transmission capacity (Tx capacity) by taking the first resource into account, the UE randomly selects a resource (second resource) on the remaining subframes other than the specific subframe (step S420).

[0167] For example, in a specific subframe, the number of transmission links in the UE may be less than the number of configured transmission carriers. Alternatively, in a specific subframe, the UE may not support a frequency band combination that includes a first resource of the first carrier and a third resource of the second carrier. Alternatively, the specific subframe may correspond to the UE's transmission link handover time.

[0168] The UE can use the first resource and the second resource to transmit a signal (step S430). The signal can be a V2X signal. The UE can apply option 1-1 above to the following situations: a) the number of transmission links is less than the number of configured transmission carriers, b) the UE does not support the given frequency band combination, or c) the subframe corresponds to the transmission link switching time.

[0169] In other cases (e.g., the UE cannot meet the RF requirements due to reasons such as PSD imbalance in subframes), the UE may follow options 1-2 as described below.

[0170] Figure 10 The illustration shows another example (Options 1-2) of resource selection for each carrier in the case of using carrier aggregation in V2X communication.

[0171] refer to Figure 10Assume that carriers #1, #2, and #3 are configured to the UE for V2X communication via carrier aggregation, and that the UE is a UE with only two transmission chains. That is, assume that the UE has the ability to transmit V2X signals to only two carriers simultaneously.

[0172] The UE can select resources for V2X communication for each carrier based on a predefined carrier order or a configured carrier order. In this case, the carrier resource selection order can be defined by considering the ProSe priority (PPPP), CBR, etc. of each packet. As a result, for example, suppose the UE independently selects resources for V2X communication in the order of carriers #1, #2, and #3.

[0173] First, the UE can select subframes 3 and 6 on carrier #1, which are not excluded during the sensing process (e.g., randomly selected). Next, the UE can randomly select resources for V2X communication on carrier #2, which are also not excluded during the sensing process. If the resources randomly selected relative to carrier #2 exceed the UE's own transmission capacity (considering the resources selected for V2X communication on the carriers where resource selection was previously completed), the UE can repeat the random resource selection relative to carrier #2 until resources exceeding its transmission capacity are selected. As a result, for example, subframes 2 and 6 can be selected on carrier #2.

[0174] Next, the UE can select (e.g., randomly select) resources for V2X communication on carrier #3. At this point, assume the UE (randomly) selects subframes 3 and 6 on carrier #3. In this case, the resources selected in subframe 3 do not exceed the UE's transmission capacity (i.e., it can transmit simultaneously on both carriers), but the resources selected in subframe 6 exceed the UE's transmission capacity (i.e., it can transmit simultaneously on both carriers). In this case, the UE can (randomly) reselect resources on carrier #3 until a subframe exceeding the UE's transmission capacity is selected. That is, the UE repeatedly reselects resources on carrier #3 until a transmission resource that the UE can support is selected.

[0175] According to option 1-1, when the UE selects transmission resources on a specific carrier, if the UE selects a specific subframe on that specific carrier and the subframe exceeds the UE's transmission capacity limit considering resources reserved (selected) on other carriers, the UE makes a (random) selection among the remaining subframes other than the specific subframe. According to option 1-2, when the UE selects transmission resources on a specific carrier, if the UE preferentially selects a (random) resource (e.g., a subframe) and the result of that resource selection exceeds the UE's transmission capacity limit considering resources reserved (selected) on other carriers, the UE repeatedly reselects transmission resources relative to the corresponding specific carrier (e.g., randomly) until a transmission resource that the UE can support is selected.

[0176] Figure 11 The illustration shows another example (Option 2) of resource selection for each carrier in the case of using carrier aggregation in V2X communication.

[0177] refer to Figure 11 Assume that carriers #1, #2, and #3 are configured for V2X communication by a UE via carrier aggregation, and that the UE has only two transmission chains. That is, assume the UE has the capability to transmit V2X signals to only two carriers simultaneously. The UE can select resources for V2X communication for each carrier based on a predefined carrier order or a configured carrier order. In this case, the carrier resource selection order can be defined by considering ProSe priority per packet (PPPP), CBR, etc.

[0178] For example, suppose the UE selects resources for V2X communication in the order of carriers #1, #2, and #3. In this case, the UE can independently perform resource selection for V2X communication on each of carriers #1, #2, and #3. As a result, for example, suppose the UE selects subframes 3 and 6 on carrier #1, subframes 6 and 8 on carrier #2, and subframes 1 and 6 on carrier #3. In this case, although subframe 6 is selected on all carriers #1, #2, and #3, the UE cannot simultaneously perform transmissions for all three carriers in subframe 6 of carriers #1, #2, and #3. That is, in subframe 6, it exceeds the UE's transmission capacity (i.e., it can transmit simultaneously on two carriers). In this case, in option 2, all transmissions in subframe 6 can be discarded, or only predefined relatively low-priority transmissions (e.g., low PPP transmissions or high CBR transmissions on the carriers) can be discarded, so that the UE's transmission capacity is not exceeded.

[0179] In particular, “UE’s limited transmission capability” can mean that the UE is unable to support (simultaneous) transmission of multiple carriers relative to a particular subframe due to the following reasons (a) to (d).

[0180] (a) The number of transport chains (Tx chains) of the UE is less than the number of transport carriers configured in the subframe.

[0181] (b) The case where the UE does not support a given frequency band combination or carrier combination in a subframe.

[0182] (c) The case where the subframe corresponds to the transmission link switching time.

[0183] (d) Situations where the UE cannot meet RF requirements due to reasons such as imbalance of power spectral density (PSD) in subframes.

[0184] exist Figure 8 Option 1-1 described herein can be applied to cases (a), (b), and (c). For case (d), if the transmission capacity of a subframe is exceeded while using it, the UE can discard the transmission in the corresponding subframe.

[0185] Alternatively, option 1-1 is applied to cases (a), (b) and (c), and for case (d), the UE may repeatedly reselect resources from the candidate resource set until a transmission resource that meets the transmission capacity is selected.

[0186] Alternatively, options 1-2 can be applied to cases (a), (b) and (c), and option 2 can be applied to case (d).

[0187] Alternatively, option 1-1 can be applied to cases (a), (b), (c), and (d).

[0188] Alternatively, options 1-2 can be applied to cases (a), (b), (c), and (d).

[0189] Alternatively, option 2 can be applied to cases (a), (b), (c), and (d).

[0190] Alternatively, option 1-1 can be applied to cases (a), (b) and (c), and option 1-2 can be applied to other cases.

[0191] (Example #2) In Example #1, the resource selection order between carriers can be (A) defined by the carrier priorities described above that are pre-configured ( / signal communication); and / or (B) defined by the highest ( / lowest) PPPP value of the V2X message transmitted on the carrier; and / or (C) defined by the carrier index; and / or (D) defined in descending ( / or ascending) order based on CBR ( / CR) measurements (and / or remaining transmission / resource usage opportunities compared with CR-LIMIT) values, etc.; and / or (E) defined randomly; and / or (F) defined as prioritizing the selection of carriers (in the same frequency band) that do not require transmission link switching (time / gap) (or synchronization reference (SYNCH.REFERENCE) carriers).

[0192] As another example, for the resource selection order among carriers, carriers in which message transmissions are performed with relatively short (or long) generation ( / transmission / resource reservation) cycles (and / or high (low) reliability requirements and / or low (or high) latency requirements) can be preferentially selected.

[0193] The above rules can be extended to apply to the above options (e.g., option 1-1, option 1-2, etc.).

[0194] (Example #3) When applying Example #1, considering the transmission link switching time problem caused by limited transmission capacity (and / or half-duplex issues (related to in-band CA)), if the number of overlapping carrier resources for each selected TTI does not meet the predefined conditions, resources on the corresponding TTI (where resource selection has been completed) can be preferentially selected until the predefined conditions are met (e.g., selecting (one or more) carrier (one or more) resources on the same TTI in the direction of maximum), and / or K TTIs before and / or after the selected (one or more) carrier (one or more) resources can be excluded from the resource selection for the carrier (such excluded resources can be used for transmission link switching time).

[0195] (Example #4) When applying Example #4, if there are no remaining TTIs that satisfy predefined conditions when resources associated with a specific carrier are selected, (A) V2X message transmissions on the corresponding carrier can be omitted, or (B) V2X message transmissions on other carriers with a PPPP value lower than (or the same as) that associated with the V2X message on the corresponding carrier (or V2X message transmissions on carriers with a lower (or the same) priority value compared to the corresponding carrier, or PPPP values ​​associated with the V2X message transmission on the corresponding carrier higher than a pre-configured ( / signaling) threshold, or priority of the corresponding carrier higher than a pre-configured ( / signaling) threshold, etc., may be allowed to be omitted. Resources overlapping with selected / reserved resources on other carriers on the time axis (e.g., to prevent V2X message transmissions with relatively high PPPP values ​​(or V2X message transmissions on carriers with relatively high priority)) may be omitted. If the latter (B) condition is not met and it cannot be performed, V2X message transmissions on the corresponding carrier may be omitted.

[0196] When applying the techniques (in part or in whole) proposed in this disclosure, the following carrier resource selection can be performed.

[0197] For a given MAC PDU, a single carrier can be provided by a higher layer for its transmission. Factors to consider in carrier selection include: 1) CBR (Continuous Base Registry), and 2) UE capabilities (e.g., number of transmission links, power budget sharing capability, transmission link retuning capability, etc.).

[0198] For a given MAC PDU, a single carrier is used for both the transmission and potential retransmission of the MAC PDU. When a carrier is selected, the selected carrier is used for all MAC PDUs in the same sidelink procedure until a resource reselection is triggered for the same sidelink procedure. However, for different sidelink procedures, changes in the transmission chain between carriers (CCs) are not excluded.

[0199] In Mode 4 CA, carrier selection rules and resource selection procedures will be described. Transmission carrier selection can be performed efficiently by considering load balancing between carriers and UE capabilities, and negative impacts on the accuracy of the sensing process due to excessive dynamic transmission carrier switching can be prevented.

[0200] Figure 12 The illustration shows an example of resource selection when CA is applied in a side link.

[0201] refer to Figure 12 The UE performs resource selection on carrier #A (the first carrier).

[0202] When a UE performs resource selection for a carrier, it can exclude any subframe from the candidate resources that meets one of the following conditions.

[0203] 1) The corresponding subframe when the count of simultaneous transmissions in the subframe reaches the UE's transmission capacity, 2) The corresponding subframe when the remaining transmission power budget is insufficient to allow additional simultaneous transmissions in the subframe, and 3) The subframe that should be used for transmission link switching time.

[0204] Such subframes are excluded from the candidate resources, and subframes that have already been selected for transmission in the previous steps are given priority.

[0205] exist Figure 12 In this paper, it is assumed that the UE has the transmission capability to perform simultaneous transmission on two carriers. For the sake of simplicity, the transmission power budget or handover time is not considered.

[0206] exist Figure 12 In the diagram, the subframes shown in gray are those determined to have no available resources through the sensing process for each carrier.

[0207] First, the UE can select subframes #4 and #7 using a random selection scheme on carrier #A. Next, the UE performs resource selection on carrier #B, and in this case, subframe #7 can be selected. Since the UE has the transmission capability to perform transmissions on two carriers simultaneously, this selection is within the UE's transmission capabilities. The UE cannot select subframe #4 on carrier #B because the corresponding subframe is excluded from the sensing process. Therefore, the UE can, for example, randomly select subframe #1.

[0208] In carrier #0, the UE can select subframes #1 and #4 as transmission subframes. In carrier #B, the UE cannot select subframe #7 because the UE's transmission capacity limit has been reached.

[0209] Simpler approaches can also be considered in reducing the complexity of UEs (standards / testing aspects or implementation methods) for half-duplex issues.

[0210] In this method, firstly, 1) if the count of simultaneous transmissions in a subframe reaches the UE's transmission capacity, the corresponding subframe is excluded; 2) if the remaining transmission power budget in a subframe is insufficient to allow additional simultaneous transmissions, the corresponding subframe is also excluded. Afterwards, the UE can randomly select resources from the remaining resources (resources not excluded during the sensing process for each carrier or resources not additionally excluded during a series of carrier resource selection processes).

[0211] For example, in Figure 12In the example, subframe 7 is excluded in carrier #C, but resource selection is not limited to subframes #1 and #4. That is, another subframe (e.g., subframe 0) can be selected.

[0212] As another example, when a UE selects a transmission carrier for a MAC PDU transmission related to a specific service generated in a set of potential transmission ( / receive) carriers provided by a higher layer, after checking the following conditions in order: 1) the service type of the MAC PDU, 2) the UE's transmission capability, and 3) the carrier CBR (or priority) (which can be interpreted as configuring ( / signaling) priority among the conditions under consideration when selecting a transmission carrier), the UE can ultimately select a transmission carrier suitable for it.

[0213] As another example, when applying the methods proposed in part or in whole of this disclosure, the transport link switching operation (and / or transport link switching gap ( / time)) may use at least one of the following: (A) a TTI not configured ( / signaled) by SLSS resources, (B) a TTI in which a resource pool bitmap is not applied (e.g., a delayed subframe), (C) a TTI in which transport resource reservation ( / selection) is not performed, (D) a TTI in which message transmission ( / reception) with a PPPP value higher than a pre-configured ( / signaled) threshold is not performed, and (E) a TTI in which transmission is performed preferentially or limitedly.

[0214] As another example, when applying the methods proposed in part or in whole of this disclosure, if a UE fails to perform a receive (and / or sense) operation on a particular TTI due to a (receive) interruption related to a transmission chain switching operation, it is assumed that a resource reservation based on all interval candidate values ​​pre-allowed by another UE on the corresponding TTI is performed, and an exclusion operation (and / or a resource (re)selection operation) of overlapping candidate resources (e.g., subframes) is performed (in the selection window).

[0215] As another example, when the methods proposed in part or in whole of this disclosure are applied, the UE can simultaneously perform (or trigger) transmission resource (re)selection ( / reservation) operations on a carrier group pre-configured ( / signaled) from the network (or eNB) (e.g., this can be interpreted as a "MULTI-CARRIER SYNCHRONIZED RESOURCE (RE)SELECTION ( / TRIGGERING) PROCEDURE", and this can be referred to as MCSSYN_RESEL).

[0216] Here, for example, the reference carrier associated with MCSSYN_RESEL can be defined as at least one of the following: (A) a carrier pre-configured (or signaled) from the network (or eNB), (B) an anchor (or reference) carrier associated with synchronization, (C) a carrier with a relatively high (or low) priority pre-configured (or signaled) carrier, (D) a carrier with a relatively high (or low) PPPP value of the transmitted (or to be transmitted) V2X message (or a carrier on which message transmission is performed with a relatively short (or long) generation ( / transmission / resource reservation) period (and / or high (low) reliability requirements and / or low (or high) latency requirements), (E) a carrier with a relatively high (or low) carrier index, and (F) a carrier with a relatively high (or low) CBR ( / CR) measurement (and / or remaining transmission / resource utilization opportunities compared with CR_LIMIT).

[0217] As an example, it can be explained that (one or more) (remaining) carriers (other than the reference carrier) belonging to the same MCSYN_RESEL carrier group share (reference carrier) resources (re)select trigger timers ( / counters), etc.

[0218] As another example, in the event of a resource (re)selection operation for a specific carrier belonging to the MCSSYN_RESEL carrier group, when resources associated with the corresponding carrier are (re)selected, the overlap (referred to as OV_RSC) of resources for each TTI (transition time interval) for one or more remaining carriers (or more) belonging to the same MCSSYN_RESEL carrier group (or more) is counted. If the OV_RSC on a particular TTI satisfies a predefined condition, the corresponding TTI can be excluded, and resources on the remaining TTIs can be randomly selected.

[0219] Appropriate conditions can be defined when OV_RSC is the same as or greater than the UE's transmission capacity (e.g., the number of supported transmission chains) and / or when OV_RSC triggers a power limiting condition. As another example, the MCCSYN_RESEL carrier group can be configured ( / signaled) in the same way as a carrier group synchronized based on (specific) anchor ( / reference) carrier sharing (time / frequency).

[0220] As another example, when applying the methods (in part or in whole) proposed in this disclosure, retransmission resources associated with a specific carrier can be selected according to the TTI consecutive to the initial transmission resources available to the UE. Here, as an example, when the corresponding rules are applied, what can be mitigated is the (excessive) transmission chain switching gap ( / time) that occurs between the initial transmission and the retransmission (in cases where a handover to another transmission carrier is (inevitably) performed due to a large time gap ( / difference).

[0221] As another example, when the methods proposed in this disclosure (in part or in whole) are applied, resource selection related to differential carriers can be performed for the UE in consecutive TTIs. This is designed, for example, to mitigate the occurrence of half-duplex issues / excessive transmission chain handover time( / gap).

[0222] As another example, when applying the methods (in part or in whole) proposed in this disclosure, in cases where the UE performs actual SLSS transmit ( / receive) operations on pre-configured ( / signaled) SLSS resources on a specific carrier (e.g., a synchronization reference carrier) (and / or where pre-configured ( / signaled) SLSS resources exist on a specific carrier), K TTIs (e.g., K = 1) before and / or after the corresponding SLSS resource can be excluded from resource selection ( / allocation) on (other) carriers (e.g., for transmission link switching time). With the application of the appropriate rules, synchronization signal transmit ( / receive) operations and PSCCH / PSSCH transmit ( / receive) operations can be performed efficiently on different carriers (in the case of in-band CA). SLSS resources can be interpreted in a broader sense as “transmission of a pre-configured (or signaled) specific channel / signal (or a message with a PPPP value higher than the pre-configured (or signaled) threshold)” or “transmission of a channel / signal on a pre-configured (or signaled) specific carrier (or a channel / signal with a carrier priority higher than the pre-configured (or signaled) threshold)”.

[0223] As another example, when the methods proposed in this disclosure (in part or in whole) are applied, as a resource selection order among carriers, the UE may preferentially execute carriers that require (or allocate) relatively high power (and / or long coverage requirements) (and / or high reliability requirements and / or low latency requirements) (channel / signal / message) transmissions.

[0224] When the corresponding rules are applied, and (in the case of in-band CA) transmission power is allocated (or calculated) on different carriers, if it is necessary to reduce the transmission power of the previously allocated carriers (channel / signal / message) due to exceeding the MPR or PSD imbalance allowable limit (considering the IMD product), the transmission on the corresponding carrier can be omitted (or the transmission power on the previously allocated carriers does not need to be reduced (or does not exceed the MPR or PSD imbalance allowable limit)).

[0225] As another example, when the methods proposed in part or in whole of this disclosure are applied, the UE can perform synchronization signal monitoring (and / or transmission) operations in a pre-configured SLSS resource on the synchronization reference carrier according to pre-configured ( / signaling) rules ( / mode / ratio) (e.g., period, subframe offset).

[0226] The corresponding synchronization signal monitoring (and / or transmission) operation may be (A) performed only in a limited manner if PSCCH / PSSCH transmission operation is not performed on the non-synchronous reference carrier (NON-SYNRFCC), and / or (B) performed by omitting PSCCH / PSSCH transmission on the non-synchronous reference carrier (NON-SYNRFCC), and / or (C) performed in the form of a UE implementation.

[0227] As another example, when applying the methods (in part or in whole) proposed in this disclosure, when the UE performs resource (re)selection / reservation for a specific carrier #X, due to reasons such as reaching transmission (chain) capacity limits, the occurrence of transmission limitation situations, or the prevention of over-reception / monitoring due to half-duplex issues, the UE should exclude (one or more) subframes (on carrier #X) and, for this purpose, require clarification of the assumption that the time / range of resource reservations for (one or more) existing other carriers on which resource selection / reservation has already been performed is maintained (or confirmed). This is because, generally, whenever a resource reselection operation is triggered for resources selected / reserved on a carrier, the determination of whether resources located at the same time / frequency are used consecutively is based on a pre-configured ( / signaled) probability. That is, the determination of the probability of resource (location) changes (and / or resource reselection / reservation operations) for (one or more) (existing) other carriers on which resource selection / reservation has already been performed is not always performed / triggered together with the (re)selection / reservation execution timing related to carrier #X.

[0228] Methods for addressing this problem include, for example, (A) assuming that resource reservations on (one or more) existing different carriers are maintained (or valid) for a pre-configured (or signaled) duration (or for an indefinite period (or duration), or (B) performing a probability determination of (future) resource (location) changes for (one or more) existing other carriers when (together or pre-) a (re)selection / reservation is performed for carrier #X (or when resource selection / reservation is performed for (one or more) corresponding carriers), or (C) assuming that resources on (one or more) existing other carriers are maintained (for a certain period of time or temporarily) (e.g., in practice, this can be interpreted as the probability determination result maintaining existing resources (locations)), or (D) assuming that resource reservations on (one or more) existing other carriers are maintained (or valid) until the resource reservation counter (e.g., triggering resource reselection / reservation when the resource selection / reservation counter becomes "0") expires (or as many as a pre-configured (or signaled) multiple of the resource reservation counter).

[0229] As another example, for a carrier used for packet transmission of a specific PPPP value, the UE can select a (transmission) carrier with a remaining transmission / resource usage opportunity compared to a CR_LIMIT value that is higher (or lower) than a pre-configured (or signaled) threshold (e.g., the CR_LIMIT value can be configured differently for each CBR / PPPP (from the network)).

[0230] Here, for example, in the presence of multiple (transmission) carriers with remaining transmission / resource usage opportunities compared to a CR_LIMIT that is higher (or lower) than the corresponding threshold, the UE can randomly select one of these. Here, for example, the corresponding thresholds can be configured (or signaled) differently for each PPPP and / or CBR and / or carrier priority and / or service type ( / category).

[0231] Typically, CBR( / CR) measurements are performed whenever an (actual) initial transmission or retransmission is performed. However, for UEs with limited transmission capacity, it may be possible that a carrier on which actual initial / retransmission is not performed temporarily, and the CBR( / CR) value used after switching to such a carrier (related to the corresponding carrier) is a measurement from a relatively long time ago (i.e., the value measured when an (actual) initial transmission or retransmission was previously performed on the corresponding carrier), and may inappropriately reflect the latest state (e.g., load) related to the corresponding carrier. To mitigate this problem, CBR( / CR) measurements for carrier #Y can be performed (additionally) based on the resource reselection / reservation trigger time of carrier #X (e.g., the carrier used for the current V2X message transmission) to carrier #Y (the target carrier for switching), provided that a handover from carrier #X (e.g., the carrier used for the current V2X message transmission) to carrier #Y (the target carrier for switching) is permitted only when a resource reselection / reservation for carrier #X is triggered.

[0232] As another example, in the case of a UE with limited transmission capacity, the UE can perform resource selection for a specific carrier according to the table below. When selecting resources related to (one or more) (specific) carriers, if (in the selection window) a subframe (combination) on the corresponding carrier that does not meet predefined conditions (e.g., a subframe (combination) that does not reach transmission capacity ( / transmission limitation)) is not maintained, according to the specific techniques in the table below (e.g., options 1-2 and / or option 1-1), (A) resource reselection operations can be performed (repeatedly or limitedly) as many times as the pre-configured ( / signaled) (maximum) count, and / or (B) resource selection operations ( / procedures) related to (one or more) carriers can be not performed ( / started) (or omitted) (this prevents resource reselection operations for (one or more) specific carriers from being excessively (or infinitely) repeated). Here, for example, when the latter (B) rule is applied, it can be interpreted that transmission operations related to (one or more) corresponding carriers are omitted. The table below summarizes... Figures 8 to 11 The options in the text.

[0233] [Table 1]

[0234]

[0235] As another example, when applying options 1-2 in Table 1, if only a portion (e.g., 1) of the multiple (e.g., 2) (random) selected resources for a specific carrier exceeds the UE's transmission capacity, the UE may (A) repeat resource reselection only for the corresponding number of selected resources until resource selection is completed without exceeding the transmission capacity, or (B) repeat resource reselection for all multiple selected resources (with respect to the corresponding carrier) until resource selection is completed without exceeding the transmission capacity.

[0236] As another example, in the case of a UE with limited transmission capacity, a (RF chain) retuning time may be required when performing a transmission carrier handover. To reduce the corresponding (RF chain) retuning time overhead, (A) when the UE selects a transmission carrier, the UE maintains the carrier until a retransmission is performed (after the initial transmission) (or until a pre-configured number (or duration) of transmissions is performed), or (B) when the UE selects resources for a specific carrier, the UE may exclude (one or more) subframes between the initial transmission and retransmission on other carriers (or the duration of the pre-configured number (or duration of the pre-configured number of transmissions (or the length of the pre-configured number of transmissions (or the length of the pre-configured number of transmissions (or the length of the pre-configured number of transmissions (or the length of the pre-configured number of transmissions (or the length of the pre-configured number of transmissions ( or ...

[0237] As another example, in the case of a UE with limited transmission capacity, when resource selection is performed for a specific carrier #X, the determination of subframe #N on carrier #X, which excludes the use of the (RF chain) retuning time (e.g., assumed to be "1 subframe"), can be performed under the following condition (A) (or if the resource selection is not located before the time of the required (RF chain) retuning time starting from subframe #N): before subframe #N of carrier #X, resource selection (or transmission) of a number of (one or more) other carriers corresponding to the transmission capacity limit of the UE itself is performed and the latest (or last) resource (or transmission) on (one or more) of the corresponding other carriers is located in subframe #N-1, subframe #N is determined to be the use of the (RF chain) retuning time and is excluded from the resource selection associated with carrier #X.

[0238] As a specific example, suppose a UE has "the number of transmission capacity limits = 2" and "the number of configured carriers = 3". In this case, if resource selection (or transmission) on carriers #1 and #3 is performed on subframes #N-1 and #N-2 respectively, subframe #N on carrier #2 is determined to be used for (RF chain) readjustment time and should be excluded from resource selection related to carrier #X. On the other hand, if resource selection (or transmission) on carriers #1 and #3 is performed on subframes #N-1 and #N-6 respectively, the UE can switch from subframe #N-4 to carrier #2, and may not need to exclude subframe #N from resource selection related to carrier #X.

[0239] As another example, when multiple (in-band) carriers are configured (or signaled) via CA, due to the half-duplex problem (i.e., when a transmit (or receive) operation is performed on the timing of subframe #N on a particular carrier, a receive (or transmit) operation is performed on the same (or partially overlapping) timing of one or more other carriers within the selection window on the particular carrier on which a resource (re)selection / reservation operation cannot be triggered), and when the pre-configured (or signaled) number of candidate resources (e.g., 20% of the total number of candidate resources in the selection window) is not guaranteed (or in the absence of remaining candidate resources), (in the absence of additional actions to increase the number of candidate resources) only the remaining candidate resources can be used to perform the transmit resource selection operation (or trigger the resource reselection operation by including one or more other carriers where the resource selection / reservation is completed).

[0240] Here, as an example, in the case where a specific subframe #P is not monitored / received due to half-duplex issues, it can be assumed that all candidate (transmission) resources that may overlap (or conflict) with the following resources within the selection window can be excluded, which are spaced from subframe #P as many times as a (candidate) resource reservation period (and / or the number of pre-configured ( / signaled) counts of (candidate) resource reservation periods).

[0241] As another example, in the case of configuring ( / signaling) (in-band) CA, and where the (transmission) resources of multiple carriers overlap on a particular subframe, the reduction in transmission power associated with some or all carriers (e.g., the possible reduction in transmission coverage) may be unavoidable due to exceeding the allowable limits of MPR or PSD imbalance (considering the IMD product).

[0242] Therefore, V2X message transmissions of (one or more) different carriers that overlap (partially) in the time domain can be limited to those V2X message transmissions with a PPPP value less than a pre-configured (or signaled) threshold.

[0243] Conversely, V2X message transmission with a corresponding threshold or greater PPPP value is performed on subframe #K of a specific carrier. When resources related to V2X messages on different carriers (e.g., messages with a corresponding threshold or less PPPP value) are selected / reserved, only one or more remaining subframes other than the corresponding subframe #K can be considered (with limited consideration). (Or V2X message transmission with a corresponding threshold or greater PPPP value on a specific carrier may not overlap (partially) with V2X message transmission resources on different carriers in the time domain (or (with limited consideration) may overlap (partially) with a maximum number of pre-configured ( / signaled) V2X message transmission resources on different carriers in the time domain).

[0244] As another example, the impact (e.g., leakage) caused by PSD imbalance between different (in-band CA) carriers can be modified based on factors such as the location (and / or number) of (scheduled) resource blocks. Therefore, when a UE performs resource selection / reservation for a specific subframe, if any of the candidate resources (or a pre-configured ( / signaled) number or more) on the specific subframe cannot satisfy the PSD imbalance allowable limit (without a reduction in transmission power) when any of the candidate resources on the specific subframe is used in the selection window, the UE can (randomly) select from the remaining (candidate resources on the subframe) excluding the corresponding subframe.

[0245] As another example, when applying option 2 described in the table, if the number of selectable resources associated with multiple carriers on a particular TTI is greater than the UE's transmission capacity (and / or if transmissions associated with multiple carriers on a particular TTI cause power limitations), the UE may omit transmissions associated with carriers on the corresponding TTI based on a descending (or ascending) order of remaining transmission / resource usage opportunities compared to CR_LIMIT.

[0246] Transmissions associated with a carrier on the corresponding TTI may be omitted until the number of selected resources associated with multiple carriers on the corresponding TTI becomes less than or equal to the UE’s transmission capacity (and / or the transmissions associated with multiple carriers on the corresponding TTI do not cause a power limiting condition).

[0247] As another example, when resource selection ( / reservation) for a specific carrier is performed together with candidate resource exclusion operations (e.g., resources occupied by another UE or high-interference resources are excluded) based on sensing operations (e.g., S-RSSI measurement, PSSCH-RSRP measurement) (in the selection window), after (additional) candidate resource exclusion operations (in the selection window) considering the aforementioned transmission capacity exceeding problem (and / or reception stoppage due to power limitation conditions and / or half-duplex problems and / or transmit chain switching problems), if there are no remaining candidate resources in the selection window (and / or if the number of pre-configured ( / signaled) candidate resources (e.g., 20% of the total number of candidate resources in the selection window) is not guaranteed), (A) in the pre-configured ( / signaled) EXCEPTIONALRESOURCE A transmission associated with the corresponding carrier is performed on the POOL (Exception Resource Pool) (once, or during a pre-configured ( / signaled) count ( / time), or the number of selectable candidate resources in the selection window is guaranteed until a pre-configured ( / signaled) threshold or greater), and / or (B) a handover / resource selection ( / reservation) is performed on a carrier on which there are a relatively large number of candidate resources (e.g., may be limited to the same service ( / priority) carriers), and / or (C) a resource reselection may be triggered (including on existing carriers on which resource selection ( / reservation) has been completed).

[0248] As another example, when carrier selection is performed on a specific carrier (within a pre-configured set of potential carriers) based on sensing operations (in the selection window) and transmission capacity exceeding issues, after considering the additional candidate resource exclusion operations (described above) (in the selection window) (and / or reception stoppage due to power limitation issues and / or half-duplex issues and / or transmission chain switching issues), in the case that there are no remaining candidate resources in the selection window (and / or in the case that the number of pre-configured candidate resources (e.g., 20% of the total number of candidate resources in the selection window) is not guaranteed), (A) the corresponding (TX) carrier can be excluded from the selection candidates, and / or (B) the priority associated with carrier selection can be defined based on the descending (or ascending) order of the remaining number of candidate resources in the selection window.

[0249] As another example, the resource selection priority (A) between carriers performing the same PPPP (and / or service) message transmission (and / or having the same CBR and / or CR and / or remaining transmission / resource usage opportunities compared to CR_LIMIT) can be defined randomly, or (B) can be defined in descending (or ascending) order of carrier index (and / or CR and / or remaining transmission / resource usage opportunities compared to CR_LIMIT).

[0250] As another example, when performing resource selection ( / reservation) for a carrier, when it is determined that a particular candidate resource in the selection window has a transmission capacity exceeding the problem (and / or a reception stoppage problem due to power limitation and / or half-duplex and / or transmit chain switching problem) (e.g., if such a problem exists, the corresponding candidate resource is (additionally) excluded), (A) only the corresponding candidate resource (time) position (subframe #N) in the selection window is considered, or (B) (not only the corresponding candidate resource (time) position ((subframe #N)) in the selection window is considered), or (based on subframe #N) one (or an infinite number of times or a pre-configured (signaled) number of times or (selected) resource reservation counters (e.g., if the resource selection / reservation counter becomes "0", triggering resource re-reservation / selection)) resource (time) (one or more) positions (e.g., subframe #(N+P) of the resource reservation period (P) of (HOP_NUM).

[0251] When the latter (B) rule is applied, the probability of the corresponding candidate resource experiencing the aforementioned problems may be relatively reduced in the future. Here, for example, "HOP_NUM" can be configured (or signaled) differently based on PPPP ( / service type) (and / or CBR ( / CR) and / or remaining transmission / resource usage opportunities compared to CR_LIMIT and / or carrier priority and / or delay ( / reliability) requirements and / or whether (HARQ) retransmission).

[0252] As another example, in the case of a UE with limited reception capabilities (e.g., where the number of receive chains is less than the number of configured receive carriers), if sensing operations are not performed beyond a pre-configured ( / signaling) time length threshold on a specific carrier due to carrier switching operations, etc., (A) message transmission (related to the specific carrier) can be omitted until the sensing result of the corresponding time length threshold is secured, and / or (B) resource selection / reservation and message transmission can be performed (on the specific carrier) using limited sensing results (e.g., this can be interpreted as a partial sensing operation), and / or (C) message transmission based on random resource selection can be performed (on the specific carrier) (until the sensing result of the corresponding time length threshold is secured), and / or (D) a pre-configured ( / signaling) exception resource pool can be used (until the sensing result of the corresponding time length threshold is secured).

[0253] As another example, when resource selection ( / reservation) for a specific carrier #X is performed together with candidate resource exclusion operations based on sensing operations (in the selection window), if message transmissions with a (relatively) higher PPPP (or higher than a pre-configured ( / signaling notification) threshold) are reserved on a different carrier #Y, this operation can be (additionally) excluded from the selection window related to carrier #X. Here, for example, when the corresponding rule is applied, since the message transmission resources of (relatively) low PPPP on carrier #X (in the time domain) overlap with the message transmission resources of (relatively) high PPPP on carrier #Y, the problem of the (relatively) low PPPP message transmission being omitted or its power being reduced can be mitigated.

[0254] As another example, when the physical layer (PHY layer) performs an (additional) candidate resource exclusion operation (referred to as EXC_PRC#B) after considering (as described above) transmission capacity exceeding the problem (and / or reception stoppage due to power limiting conditions and / or half-duplex problems and / or transmit chain switching problems) and similar problems (in the selection window), and performs a candidate resource exclusion operation based on sensing operations (in the selection window) (referred to as EXC_PRC#A), and forwards the remaining candidate resources (information) to the MAC layer (in the selection window), the pre-configured ( / signaled) condition of "guaranteed number of candidate resources (e.g., 20% of the total number of candidate resources in the selection window)" related to (existing) EXC_PRC#A may not be applied (in the selection window).

[0255] Since examples of the methods proposed above can also be included in the methods of this disclosure, it is obvious that examples of the proposed methods can be considered as a proposed method. Furthermore, the proposed methods can be implemented independently, but can also be implemented as a combination (or merging) of methods.

[0256] For example, although the proposed method is described based on a 3GPP LTE / LTE-A system for ease of explanation, the system to which the proposed method is applied can also be extended to another system besides the 3GPP LTE / LTE-A system. For example, the proposed method of this disclosure can also be extended to D2D communication. In this document, D2D communication refers to a UE communicating directly with different UEs using a radio channel. In this document, although UE refers to a user terminal, a UE can also be considered a UE when a network device such as an eNB transmits and / or receives signals according to a communication scheme between UEs.

[0257] Furthermore, the methods proposed in this disclosure can be applied only to Mode 3 V2X operations (and / or Mode 4 V2X operations).

[0258] Furthermore, the proposed method of this disclosure can be applied only to pre-configured ( / signaling) (specific) V2X channel ( / signaling) transmissions (e.g., PSSCH (and / or (interlinked) PSCCH and / or PSBCH)).

[0259] Furthermore, the proposed method of this disclosure can be applied only in a limited way to situations where PSSCH and (interlinked) PSCCH (in the frequency domain) are transmitted adjacently (and / or non-adjacently) (and / or transmissions are performed based on pre-configured ( / signaled) MCS (and / or coding rate and / or resource block) (values ​​( / ranges)).

[0260] Furthermore, the proposed method of this disclosure can be applied only in a limited way to mode #3 (and / or mode #4) V2X carriers (and / or (mode #4 ( / 3) side link ( / uplink) SPS) (and / or side link ( / uplink) dynamic scheduling) carriers).

[0261] Furthermore, the proposed method of this disclosure can be applied only (limitedly) to situations where the location and / or quantity of synchronization signal (transmission (and / or reception)) resources (and / or the subframe location related to the V2X resource pool and / or number (and / or subchannel size and / or number)) are the same (and / or (partially) different).

[0262] Furthermore, the proposed method of this disclosure can be extended to apply when a UE with a transmission (chain) capability (configured by higher layers) less than the number of transmission carriers selects resources for each carrier and when a UE with limited capability (re)selects resources.

[0263] Figure 13 This is a block diagram of an apparatus for implementing embodiments of the present disclosure.

[0264] refer to Figure 13 The device 1000 includes a processor 1100, a memory 1200, and a transceiver 1300. The processor implements the proposed functions, procedures, and / or methods. The device 1000 can be a UE or an eNB. The transceiver 1300 is connected to the processor 1100 and transmits / receives radio signals. The memory 1200 can store information required for the operation of the processor 1100, and can also store transmitted / received signals.

[0265] Figure 14 The diagram illustrates an example of a processor 1100 configuration.

[0266] refer to Figure 14 The processor 1100 may include a resource selection module 1101 and a suitability determination module 1102. The resource selection module 1101 may select transmission resources for V2X signal transmission for each carrier. The suitability determination module 1102 may include a CP removal module for removing cyclic prefixes (CP) from the received signal, a phase rotation module for phase rotation, a Fast Fourier Transform (FFT) module, a Channel Estimation (CE) module, a Single-Input Multiple-Output (SIMO) decoder, an Inverse Discrete Fourier Transform (IDFT) module, a Log-Likelihood Ratio (LLR) calculation module, a descrambling module, a decoder chain, etc.

[0267] The processor may include application-specific integrated circuits (ASICs), other chipsets, logic circuits, and / or data processing devices. The memory may include read-only memory (ROM), random access memory (RAM), flash memory, memory cards, storage media, and / or other storage devices. The RF unit may include baseband circuitry for processing radio signals. When the embodiments are implemented in software, the above techniques can be implemented using modules (procedures, functions, etc.) that perform the above functions. Modules may be stored in memory and can be executed by the processor. The memory may be located internally or externally to the processor and may be coupled to the processor by various known means.

Claims

1. A method for transmitting vehicle-to-everything (V2X) signals of a user equipment (UE) with transmission capability in a wireless communication system, the method comprising: Determine the order of the first and second carriers; Select a first resource in the first carrier; Based on the consideration that using a specific subframe on the second carrier exceeds the transmission capacity of the UE while taking into account the first resource, a second resource excluding the specific subframe is randomly selected on the second carrier; and The V2X signal is transmitted using the first resource and the second resource. wherein The selection of the first resource on the first carrier prior to the selection of the second resource on the second carrier is based on the order of the first carrier and the second carrier, and The order is determined based on i) the ProSe priority (PPPP) of each packet of the V2X signal and ii) the channel busy rate (CBR).

2. The method of claim 1, wherein, The number of transmission carriers supported by the UE is less than the number of transmission carriers configured in the specific subframe.

3. The method of claim 1, wherein, The first carrier and the second carrier are configured to the UE via carrier aggregation.

4. A user equipment (UE), comprising: At least one transceiver, the at least one transceiver being configured to transmit and receive radio signals; as well as At least one processor, which operates in conjunction with the at least one transceiver, wherein the at least one processor is configured to: Determine the order of the first and second carriers; Select a first resource in the first carrier; Based on the consideration that using a specific subframe on the second carrier exceeds the transmission capacity of the UE while taking into account the first resource, a second resource excluding the specific subframe is randomly selected on the second carrier; and Use the first and second resources to send vehicle-to-everything V2X signals. The selection of the first resource on the first carrier before selecting the second resource on the second carrier is based on the order of the first carrier and the second carrier, and The order is determined based on i) the ProSe priority (PPPP) of each packet of the V2X signal and ii) the channel busy rate (CBR).

5. The UE of claim 4, wherein, The number of transmission carriers supported by the UE is less than the number of transmission carriers configured in the specific subframe.

6. The UE according to claim 4, wherein, The first carrier and the second carrier are configured to the UE via carrier aggregation.

7. An apparatus in a wireless communication system, the apparatus comprising: At least one memory; as well as At least one processor, said at least one processor being operatively connected to said at least one memory, Wherein, the at least one memory stores instructions, the instructions causing the at least one processor to perform an operation based on execution by the at least one processor, the operation including: Determine the order of the first and second carriers; Select a first resource in the first carrier; Based on the consideration that using a specific subframe on the second carrier exceeds the transmission capacity of the user equipment (UE) when considering the first resource, a second resource in the second carrier is randomly selected to exclude the specific subframe; and Use the first and second resources to send vehicle-to-everything V2X signals. The selection of the first resource on the first carrier before selecting the second resource on the second carrier is based on the order of the first carrier and the second carrier, and The order is determined based on i) the ProSe priority (PPPP) of each packet of the V2X signal and ii) the channel busy rate (CBR).

8. The apparatus according to claim 7, wherein, The number of transmission carriers supported by the UE is less than the number of transmission carriers configured in the specific subframe.

9. The apparatus according to claim 7, wherein, The first carrier and the second carrier are configured to the UE via carrier aggregation.

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