APPARATUSES, METHODS, AND SYSTEMS FOR INCREASING THE TRANSMISSION RELIABILITY FOR TRANSMISSIONS OF A DUPLICATION BEARER IN A SHARED SPECTRUM

Apparatuses, methods, and systems are disclosed for increasing the transmission reliability for transmissions of a duplication bearer in a shared or unlicensed spectrum. A UE apparatus for a mobile network (“NW”) includes a transceiver that initiates a listen before talk procedure (“LBT”) on shared spectrum, for transmission of a medium access control (“MAC”) protocol data unit (“PDU”) containing an original packet data convergence protocol (“PDCP”) PDU of a data radio bearer (“DRB”) configured for PDCP duplication, wherein PDCP duplication is deactivated for the DRB. The apparatus includes a processor that determines whether the LBT failed or succeeded and selectively enables PDCP duplication for the DRB in response to determining that the PDCP PDU was not transmitted due to failure of the LBT.

FIELD

The subject matter disclosed herein relates generally to wireless communications and more particularly relates to apparatuses, method, and systems for increasing the transmission reliability for transmissions in a network (“NW”) that supports shared spectrum.

BACKGROUND

Some wireless communications systems support packet duplication for both user plane data, as well as control plane data, in order to increase the reliability of transmissions, i.e., by having the diversity gain. Duplication is a function of the Packet Data Convergence Protocol (“PDCP”) layer, e.g., PDCP Protocol Data Units (“PDUs”) are duplicated. Services that benefit from duplication include URLLC or Signaling Radio Bearers (“SRBs”). In various systems, a network (“NW”) configures a data radio bearer (“DRB”) for packet data convergence protocol (“PDCP”) duplication and the NW may activate or deactivate PDCP duplication. In existing systems, a user equipment (“UE”) performs PDCP duplication in accordance with the configuration and activation/deactivation provided by the NW.

BRIEF SUMMARY

Apparatuses for increasing the transmission reliability for transmissions of a duplication bearer (e.g., a data radio bearer (“DRB”) configured for packet data convergence protocol (“PDCP”) duplication) in a shared spectrum. In one or more embodiments, a User Equipment (“UE”) apparatus for a mobile network (“NW”) includes a transceiver that initiates a listen before talk procedure (“LBT”) on shared spectrum, for transmission of a medium access control (“MAC”) protocol data unit (“PDU”) containing an original packet data convergence protocol (“PDCP”) PDU of a data radio bearer (“DRB”) configured for PDCP duplication, wherein PDCP duplication is deactivated for the DRB. The apparatus further includes a processor that: determines whether the LBT failed or succeeded; and selectively enables PDCP duplication for the DRB in response to determining that the PDCP PDU was not transmitted due to failure of the LBT. Various methods and systems may perform the functions of the apparatus.

A method for increasing the transmission reliability for transmissions of a duplication bearer (e.g., a DRB configured for PDCP duplication) that supports shared spectrum. In one or more embodiments, the method includes initiating a listen before talk procedure (“LBT”) on shared spectrum, for a transmission of a medium access control (“MAC”) protocol data unit (“PDU”) containing an original packet data convergence protocol (“PDCP”) PDU of a data radio bearer (“DRB”) configured for PDCP duplication, wherein PDCP duplication is deactivated for the data radio bearer. In various embodiments, the method further includes determining whether the LBT failed or succeeded and selectively enabling PDCP duplication for the DRB in response to determining that the PDCP PDU was not transmitted due to failure of the LBT.

DETAILED DESCRIPTION

FIG.1is a schematic block diagram illustrating a wireless communication system100for selectively enabling PDCP duplication for a data radio bearer in a network120that supports shared spectrum, in accordance with one or more embodiments of the disclosure. according to embodiments of the disclosure. In one embodiment, the wireless communication system100includes at least one remote unit105, an access network120containing at least two base units110, wireless communication links115, and a mobile core network140. Even though a specific number of remote units105, access networks120, base units110, wireless communication links115, and mobile core networks140are depicted inFIG.1, one of skill in the art will recognize that any number of remote units105, access networks120, base units110, wireless communication links115, and mobile core networks140may be included in the wireless communication system100. In another embodiment, the access network120contains one or more WLAN (e.g., Wi-Fi™) access points.

In one implementation, the wireless communication system100is compliant with the 5G system specified in the 3GPP specifications. More generally, however, the wireless communication system100may implement some other open or proprietary communication network, for example, LTE or WiMAX, among other networks. The present disclosure is not intended to be limited to the implementation of any particular wireless communication system architecture or protocol.

In some embodiments, the remote units105may communicate with a remote host151via a data path125that passes through the mobile core network140and a data network150. For example, a remote unit105may establish a PDU connection (or a data connection) to the data network150via the mobile core network140and the access network120. The mobile core network140then relays traffic between the remote unit105and the remote host151using the PDU connection to the data network150.

The base units110may be distributed over a geographic region. In certain embodiments, a base unit110may also be referred to as an access terminal, an access point, a base, a base station, a Node-B, an eNB, a gNB, a Home Node-B, a relay node, a device, or by any other terminology used in the art. The base units110are generally part of a radio access network (“RAN”), such as the access network120, that may include one or more controllers communicably coupled to one or more corresponding base units110. These and other elements of the radio access network are not illustrated, but are well known generally by those having ordinary skill in the art. The base units110connect to the mobile core network140via the access network120.

The base units110may serve a number of remote units105within a serving area, for example, a cell or a cell sector via a wireless communication link115. The base units110may communicate directly with one or more of the remote units105via communication signals. Generally, the base units110transmit DL communication signals to serve the remote units105in the time, frequency, and/or spatial domain. Furthermore, the DL communication signals may be carried over the wireless communication links115. The wireless communication links115may be any suitable carrier in licensed or unlicensed radio spectrum. The wireless communication links115facilitate communication between one or more of the remote units105and/or one or more of the base units110.

In one embodiment, the mobile core network140is a 5G core (“5GC”) or the evolved packet core (“EPC”), which may be coupled to a data network150, like the Internet and private data networks, among other data networks. Each mobile core network140may belong to a single public land mobile network (“PLMN”). The present disclosure is not intended to be limited to the implementation of any particular wireless communication system architecture or protocol.

The mobile core network140includes several network functions (“NFs”). As depicted, the mobile core network140includes multiple control plane functions including, but not limited to, an Access and Mobility Management Function (“AMF”)143, a Session Management Function (“SMF”)145, and a Policy Control Function (“PCF”). Additionally, the mobile core network140includes a user plane function (“UPF”)141and a Unified Data Management (“UDM”)147. Although specific numbers and types of network functions are depicted inFIG.1, one of skill in the art will recognize that any number and type of network functions may be included in the mobile core network140.

Disclosed herein are methods, systems, and apparatuses for efficient activation/deactivation of PDCP duplication for both CA- and DC-based architectures. To efficiently activate and/or deactivate packet duplication (e.g., PDCP duplication), a base unit110signals to the remote unit105, e.g., a first control signal. This signaling may be PDCP control signaling, MAC control signaling, or RRC signaling. For 3GPP networks, the 5G radio Radio Access Technology (“RAT”) (referred to as New Radio, “NR”) supports packet duplication for data on both the user plane and the control plane, e.g., in order to increase the reliability of transmissions by having the diversity gain. As mentioned above, this packet duplication is a function of the PDCP layer, such that PDCP PDUs are duplicated.

PDCP duplication benefits services such as URLLC, where transmission reliability and latency enhancements are two key aspects. Moreover, redundancy/diversity schemes in Carrier Aggregation (“CA”) scenarios can be used to reach the reliability and latency requirements of URLLC. For URLLC, two independent transmission channels on different carriers may be needed for extreme-reliability cases such as error rates of 10−5to 10−9within a given latency bound. Here, duplication based on CA is a tool available to the scheduler to further improve the transmission reliability. However, where reliability on one of the carriers cannot be guaranteed, it is thus beneficial to have further carrier(s) available. As an example, such a situation may be due to a temporary outage/fading dip, due to unanticipated change or wrong channel state information.

Packet duplication may be also applied based on Dual Connectivity (“DC”) architecture, e.g., split bearer operation with PDCP duplication. In a general sense, packet duplication may be used together with different diversity schemes involving more than one radio link to serve a UE. While the below embodiments focus on DC and CA scenarios, the present disclosure is not intended to be limited to those implementations.

Generally, packet duplication is limited to those situations where the extra reliability is needed, e.g., dynamic activation/deactivation. Here, PDCP control signaling or MAC control signaling (e.g., MAC control element (“CE”)) may be used to activate/deactivate the PDCP duplication. Beneficially, this also reduces the overhead of activation/deactivation of the PDCP duplication. Currently, PDCP duplication is generally configured and activated/deactivated by the NW but there are no procedures for a UE to selectively and/or autonomously active/deactivate PDCP duplication in a flexible, dynamic manner in a shared spectrum where LBT procedures are performed before transmission.

In one embodiment, the remote unit105is configured with a split bearer, e.g., for dual connectivity. In such embodiments, the default state for PDCP duplication at the split bearer may be deactivated, wherein the base unit110explicitly activates PDCP duplication by sending the first control signal. In another embodiment, the remote unit105communicates with the access network120using carrier aggregation, the remote unit105being configured with at least one bearer which has a PDCP entity which is associated with two logical channels/RLC entities being mapped to different serving cells. In such embodiments, the default state for PDCP duplication of the bearer may be deactivated, wherein the base unit110explicitly activates PDCP duplication by sending the first control signal.

In one embodiment when duplication is selectively activated or enabled by the remote unit105, the remote unit105removes PDCP PDUs from transmission buffer associated with one logical channel/RLC entity which were already successfully transmitted via the other logical channel/RLC entity, e.g., in order to avoid that the transmission buffer is piling up. The removal (discarding) of packets may be based on received RLC status reports, according to one or more embodiments. Here, a RLC layer at the remote unit105informs a PDCP layer about the successfully transmitted PDCP PDUs. The PDCP layer may then send a PDCP discard notification to the other RLC entity. Further details about discarding of duplicated PDCP PDUs and related PDUs at other layer is provided below with respect toFIGS.4,5, and6.

A Work Item Description WID for Rel-17 titled “Enhanced Industrial Internet of Things (IoT) and ultra-reliable and low latency communication (“URLLC”) support for NR″ describes industrial usage of mobile networks where ultra-reliable and low latency communication are important.

The achievable latency and reliability performance of NR may need to be extended to support use cases with tighter requirements. In order to extend the NR applicability in various verticals, the SI of NR Industrial Internet of Things (“IIoT”) has concluded that certain enhancements of RAN features in different layers should be specified for Rel-16. A Release 16 work item delivered part of the intended enhancements and also email discussions prior RAN #86 identified additional improvement needs, which are reflected in the Release 17 WI.

In Technical Specification Group Service and System Aspects (“TSG-SA”) certain side enhancements for supporting Time-Sensitive Communications (“TSC”) as defined in TR 23.734 are considered to enable accessing market beyond a Time-Sensitive Networking (“TSN”) solution included in Release 16 (which can address only a small part of the industrial automation market).

The support of unlicensed operation needs checking if Release 16 features need any additions to enable operation on Frequency Range 1 (410 MHz-7125 MHz) (“FR1”), especially in controlled environments, which assumes an environment which contains only devices operating on the unlicensed band installed by the facility owner and where unexpected interference from other systems and/or radio access technology happens only sporadically.

Certain aspects to support an enhanced Industrial Internet of Things (IIoT) together with ultra-reliable and low latency communication (“URLLC”) support for NR where further specifications and new apparatuses and methods would be beneficial include the following:1) Required Physical Layer feedback enhancements for meeting URLLC requirements such as: a) UE feedback enhancements for HARQ-ACK; b) CSI feedback enhancements to allow for more accurate MCS selection.2) Uplink enhancements for URLLC in unlicensed controlled environments such as a) Support for UE-initiated COT for FBE with minimum specification effort; and b) Harmonizing UL configured-grant enhancements in NR-U and URLLC introduced in Rel-16 to be applicable for unlicensed spectrum.3) Intra-UE multiplexing and prioritization of traffic with different priority such as: a) multiplexing behavior among HARQ-ACK/SR/CSI and PUSCH for traffic with different priorities, including the cases with UCI on PUCCH and UCI on PUSCH; and b) PHY prioritization of overlapping dynamic grant PUSCH and configured grant PUSCH of different PHY priorities on a BWP of a serving cell including the related cancelation behavior for the PUSCH of lower PHY priority, taking the solution developed during Rel-16 as the baseline.4) Enhancements for support of time synchronization such as: a) RAN impacts of SA2 work on uplink time synchronization for TSN; and b) Propagation delay compensation enhancements (including mobility issues, if any).5) RAN enhancements based on new QoS related parameters if any, e.g., survival time, burst spread, decided in SA2.

Accordingly, this disclosure addresses the following issues regarding RAN enhancements based on new QoS related parameters, e.g., survival time, in the context of PDCP duplication in a shared or unlicensed spectrum, where a communication latency and reliability target is to be achieved: a) reducing the impact of LBT failures for the transmission of PDCP duplicates for reliability and latency critical URLLC traffic; and b) avoiding the expiry of a survival timer associated with a bearer due to LBT failures.

PDCP Duplication/Support of Survival Time

PDCP duplication is a beneficial feature adopted by Rel-15 to facilitate URLLC, which can be conducted in both downlink and uplink. The NR IIoT Study Item aims to further enhance such feature in order to improve both performance and efficiency of the scheme. In the objective of the Study Item on NR Industrial Internet of Things (NR-IIoT), the following has been approved: “Enhancements (e.g., for scheduling) to satisfy QoS for wireless Ethernet when using TSN traffic patterns as specified in TR 22.804”. The survival time is a new QoS parameter introduced by IIoT applications related to the application availability. It can be viewed as an ultimate “rescuing” period available after a message failure before the application is declared “unavailable”. It is best explained by the following excerpt from TR22.804.

FIG.2is a timing diagram illustrating up time, down time and up state, down state, also showing survival time, in accordance with one or more embodiments of the disclosure. The flow of events inFIG.2is as follows. The network205is up and running (solid vertical line underneath the word “UP” indicates up state). A source device210starts sending messages215(sloping arrows) to a target device220, on which an automation function e.g., an application230is running. A communication service225is, from the point of view of the target application230, in an up state (solid vertical line is shown under “UP”). The up/down state of the application230is based on correctly received messages215. Note that the up time interval of the application230starts later than the up state of the network205, i.e., with the receipt of the first message215from the source device210.

The network205transitions into a down state if it no longer can support end-to-end transmission of the source device's messages215to the target device220according to the negotiated communication QoS. Once the application230on the target device220senses the absence of expected messages (“Deadline for expected message”235inFIG.2), it will wait a pre-set period before it considers the communication service to be unavailable (“Deadline for message reception”240inFIG.2). This is the so-called survival time245. The survival time245can be expressed as a period of time or, especially with cyclic traffic, as a maximum number of consecutive incorrectly received or lost messages. If the survival time245has been exceeded, the application transitions the status of the communication service into a down state (solid line of application230changes to DOWN inFIG.2).

The application will usually take corresponding actions for handling such situations of unavailable communication services. For instance, it will commence an emergency shutdown. Note that this does not imply that the target application is shut off; rather it transitions into a pre-defined state, e.g., a safe state. As a general rule, the target application230still “listens” to incoming packets or may try to send messages to the source device210or source application. Once the network205/communication service225is in the up state again (solid line inFIG.2changes to UP), the communication service state as perceived by the target application will change to the up state.

The communication service225is thus again perceived as available (solid line of communication service changes to UP inFIG.2) as soon as a message is correctly received by the application at the target device. The state of the application, however, depends on the counter measures taken by the application. The application might stay in down state if it is in a safe state due to an emergency shutdown. Or, the application may do a recovery and change to up state again.

FIG.3is a timing diagram illustrating a fixed frame period structure300, in accordance with one or more embodiments of the disclosure. In a FBE (frame based equipment) mode of operation, the remote unit105or base unit110(e.g., device/network node) performs LBT in an idle period305and once acquired, the channel/medium, the device/network node can communicate within the non-idle time of a fixed frame period (“FFP”)315duration (referred to as channel occupancy time (COT)310). In certain specifications/regulations, the idle period305is not shorter than the maximum of 5% of the FFP315and 100 microseconds.

FIG.4is a diagram illustrating PDCP duplication400in a case of carrier aggregation (“CA”), in accordance with one or more embodiments of the disclosure. The depicted example illustrates PDCP PDU duplication which may be configured, enabled, activated, and/or deactivated by the NW or, in accordance with one or more embodiments of the present disclosure, may be selectively enabled (e.g., autonomously) by a UE in response to a failed LBT. It may be noted that references to PDCP PDUs duplicates415may in certain embodiments, such as for example, embodiments describing the total number of PDCP PDU generated for transmission refer to both the original PDCP PDU415aand the one or more duplicated PDCP PDUs415bbecause the original PDCP PDUs and the duplicated PDCP PDUs are essentially the same.

For the PDCP duplication400illustrated for CA, cell restriction functionality440is introduced in order to ensure that the same PDCP PDUs (original PDCP PDU415aand duplicate PDCP PDU415b) are not transmitted on the same cell/carrier, e.g., to ensure that original PDCP PDU415aand its duplicate PDCP PDU415bare not both transmitted on CellA/CarrierA455aand are not both transmitted on CellB/CarrierB455b, which would effectively eliminate diversity gain that would occur, for example, by transmitting the original PDCP PDU415aon Cell A/Carrier A455aand transmitting the one or more duplicate PDCP PDU415bon a different cell/carrier such as Cell B/Carrier B455b. In various embodiments, such LCH carrier restrictions440for logical channels (“LCHs”) associated with a duplication radio bearer may be configured with an information element (“IE”) allowedServingCells indicating on which cells/carriers data of a particular logical channel can be transmitted. In some embodiments, other signals or messages known to one of skill in the art may be used to configure LCH carrier restrictions or other duplication parameters.

Operation in Unlicensed Spectrum

Devices/network nodes such as UEs and gNBs operating in unlicensed/shared spectrum may be required to perform a Listen-Before-Talk (“LBT”) procedure, e.g., channel sensing, or clear channel assessment (“CCA”) prior to being able to transmit in the unlicensed spectrum. If the device/network node performing LBT does not detect the presence of other signals in the channel, the medium/channel is considered available for transmission.

The following terminologies are defined as follows:

A channel refers to a carrier or a part of a carrier consisting of a contiguous set of resource blocks (“RBs”) on which a channel access procedure is performed in shared spectrum.

Like LBT, a channel access procedure (“CAP”) is a procedure based on sensing that evaluates the availability of a channel for performing transmissions. The basic unit for sensing is a sensing slot with a duration Tsl=9 us. The sensing slot duration Tslis considered to be idle if an eNB/gNB or a UE senses the channel during the sensing slot duration, and determines that the detected power for at least 4 us within the sensing slot duration is less than energy detection threshold XThresh. Otherwise, the sensing slot duration Tslis considered to be busy.

A channel occupancy refers to transmission(s) on channel(s) by eNB/gNB/UE(s) after performing the corresponding channel access procedures (e.g., as described in 3GPP TS 37.213).

A Channel Occupancy Time (e.g., such as COT310depicted inFIG.3) refers to the total time for which eNB/gNB/UE and any eNB/gNB/UE(s) sharing the channel occupancy perform transmission(s) on a channel after an eNB/gNB/UE performs the corresponding channel access procedures described in this clause. For determining a Channel Occupancy Time, if a transmission gap is less than or equal to 25 us, the gap duration is counted in the channel occupancy time. A channel occupancy time can be shared for transmission between an eNB/gNB and the corresponding UE(s).

A DL transmission burst is defined as a set of transmissions from an eNB/gNB without any gaps greater than 16 us. Transmissions from an eNB/gNB separated by a gap of more than 16 us are considered as separate DL transmission bursts. An eNB/gNB can transmit transmission(s) after a gap within a DL transmission burst without sensing the corresponding channel(s) for availability.

A UL transmission burst is defined as a set of transmissions from a UE without any gaps greater than 16 us. Transmissions from a UE separated by a gap of more than 16 us are considered as separate UL transmission bursts. A UE can transmit transmission(s) after a gap within a UL transmission burst without sensing the corresponding channel(s) for availability.

As shown in Table 1 below, four Channel Access Priority Classes are defined which can be used when performing uplink and downlink transmissions in Licensed Assisted Access (“LAA”) carriers (see 3GPP TS 37.213 Table 4.2.1-1).

For uplink transmissions that are dynamically scheduled, the eNB/gNB/base station selects the Channel Access Priority Class taking into account the lowest priority QoS Class Identifier (“QCI”) in a Logical Channel Group (“LCG”). For UE-initiated uplink transmission on configured grant resources respectively for AUL transmissions, the UE selects the lowest channel access priority class (i.e., highest signaled value) of the logical channel with MAC SDU multiplexed into the Medium Access Control (“MAC”) PDU. MAC Control Elements (“CEs”), other than padding buffer status report (“BSR”) use the highest channel access priority class (i.e., lowest signaled value).

Since exceeding the survival time245(shown inFIG.2) has quite severe consequences, i.e., the status of the communication service225transitions to a “down state”, it is beneficial to ensure that transmissions of delay sensitive applications, e.g., TSN traffic flows, are correctly received within the end-to-end latency budget in order to avoid the unavailable time, i.e., a down state. Therefore, the Radio Access Network (“RAN”) beneficially reacts quickly to increase the reliability of the wireless link for the concerned traffic flow(s), in particular when operated in a shared or unlicensed spectrum where LBT failures may occur for uplink transmissions. The present disclosure includes several embodiments which allow a fast reaction to LBT failures over the wireless channel by a UE dynamically and selectively enabling PDCP duplication.

Various embodiments of the apparatuses, and methods described below beneficially increase the transmission reliability for high reliable transmission in a shared spectrum in order to avoid e.g., a situation such as depicted inFIG.2where an attempted transmission exceeds the survival time245, which would in turn trigger the application to transition the status of the communication service225into a down state. The various embodiments may also be applicable for a situation in which the communication service225is a DOWN state, so as to quickly recover and bring the communication service225status back to the UP state.

FIG.5depicts a user equipment apparatus500that may be used for selectively enabling duplication of PDCP PDUs for a radio bearer, according to one or more embodiments of the disclosure. The user equipment apparatus500may include an instance of the remote unit105and/or UE205. Furthermore, the user equipment apparatus500may include a processor505, a memory510, an input device515, an output device520, and a transceiver525. In some embodiments, the input device515and the output device520are combined into a single device, such as a touch screen. In certain embodiments, the user equipment apparatus500does not include any input device515and/or output device520.

As depicted, the transceiver525includes at least one transmitter530and at least one receiver535. Additionally, the transceiver525may support at least one network interface540. Here, the at least one network interface540facilitates communication with an eNB or a gNB (e.g., using the Uu interface). Additionally, the at least one network interface540may include an interface used for communications with an UPF and/or AMF.

The processor505, in one embodiment, may include any known controller capable of executing computer-readable instructions and/or capable of performing logical operations. For example, the processor505may be a microcontroller, a microprocessor, a central processing unit (“CPU”), a graphics processing unit (“GPU”), an auxiliary processing unit, a field programmable gate array (“FPGA”), or similar programmable controller. In some embodiments, the processor505executes instructions stored in the memory510to perform the methods and routines described herein. The processor505is communicatively coupled to the memory510, the input device515, the output device520, and the transceiver525.

Referring again toFIG.4, as well as toFIG.5, in some embodiments, the processor505establishes a radio bearer to communicate with a mobile communication network. Here, the radio bearer includes a PDCP protocol entity410at the PDCP layer405of a protocol stack, a first RLC protocol entity425aand one or more second RLC protocol entities425bbeing associated with the PDCP protocol entity410, a first logical channel LCH1being associated with said first RLC protocol entity425a, and a second logical channel LCH2being associated with the second RLC protocol entity425b. In various embodiments, at the MAC layer430, the radio bearer may include a MAC entity435athat takes into account LCH carrier restrictions440when performing multiplexing and assembly. The MAC entity435amay include a first HARQ entity445aand a second HARQ entity445bassociated respectively with first and second PHYs455a,455bin physical layer450.

The memory510, in one embodiment, is a computer readable storage medium. In some embodiments, the memory510includes volatile computer storage media. For example, the memory510may include a RAM, including dynamic RAM (“DRAM”), synchronous dynamic RAM (“SDRAM”), and/or static RAM (“SRAM”). In some embodiments, the memory510includes non-volatile computer storage media. For example, the memory510may include a hard disk drive, a flash memory, or any other suitable non-volatile computer storage device. In some embodiments, the memory510includes both volatile and non-volatile computer storage media. In some embodiments, the memory510stores data relating to duplicating PDCP PDUs for a radio bearer, for example storing indications to activate/deactivate packet duplication, indications of successful transmission of PDCP data PDUs, and the like. In certain embodiments, the memory510also stores program code and related data, such as an operating system or other controller algorithms operating on the user equipment apparatus500and one or more software applications.

The input device515, in one embodiment, may include any known computer input device including a touch panel, a button, a keyboard, a stylus, a microphone, or the like. In some embodiments, the input device515may be integrated with the output device520, for example, as a touchscreen or similar touch-sensitive display. In some embodiments, the input device515includes a touchscreen such that text may be input using a virtual keyboard displayed on the touchscreen and/or by handwriting on the touchscreen. In some embodiments, the input device515includes two or more different devices, such as a keyboard and a touch panel.

In certain embodiments, the output device520includes one or more speakers for producing sound. For example, the output device520may produce an audible alert or notification (e.g., a beep or chime). In some embodiments, the output device520includes one or more haptic devices for producing vibrations, motion, or other haptic feedback. In some embodiments, all or portions of the output device520may be integrated with the input device515. For example, the input device515and output device520may form a touchscreen or similar touch-sensitive display. In other embodiments, all or portions of the output device520may be located near the input device515.

The transceiver525communicates with one or more network functions of a mobile communication network. The transceiver525operates under the control of the processor505to transmit messages, data, and other signals and also to receive messages, data, and other signals. For example, the processor505may selectively activate the transceiver (or portions thereof) at particular times in order to send and receive messages. The transceiver525may include one or more transmitters530and one or more receivers535.

FIG.6is a diagram600illustrating an overview of certain actions of UE for selectively enabling PDCP duplication for a data radio bearer in a network that supports shared spectrum, in accordance with one or more embodiments of the disclosure.

In various embodiments, a UE500,605receives configuration information (e.g., from a NW e.g., via a gNB610) for a duplication bearer (e.g., a DRB configured for PDCP duplication). For shared spectrum, the UE500,605performs a LBT615for a pending transmission/retransmission. If the LBT is successful, the UE500,605, transmits620the original PDCP PDU and in various embodiments, removes corresponding duplicate PDCP PDUs that may have been pre-generated and stored at one or more RLC entities. In one or more embodiments, if the LBT fails, the UE500,605selectively enables625duplicate PDCP transmission in accordance with one or more embodiments of the disclosure, such as in one or more of the six embodiments described in the sections that follow. In some embodiments, in the case of such LBT failures, the UE500,605further transmits or retransmits the one or more duplicated PDCP PDUs stored in the RLC entities, until, in certain embodiments, the UE500,605receives635an acknowledgement that the transmission was successful and removes corresponding duplicate PDCP PDUs from the buffer of or more entities (e.g., PDCP, RLC, MAC) in the DRB. It may be noted that in the following section, reference is made to various elements depicted in various figures such asFIGS.4,5, and6.

According to a first embodiment, configuration information received by the remote unit e.g., UE605, indicates which of the associated Radio Link Control (“RLC”) entities (e.g.,425a,425b) or LCHs (e.g., LCH1433a, LCH2433b) are to be used for PDCP duplication as well as the maximum number of PDCP duplicates (e.g.,415b) to be sent. A radio bearer being configured for duplication may have a set of associated RLC entities425and corresponding LCHs LCH1, LCH2. The set of RLC entities425may include a primary RLC entity425aand one or more secondary RLC entities425bbut only a subset of the set of RLC entities is configured by the NW to be used for duplication. According to the NW configuration, a UE500,605duplicates PDCP SDUs/PDUs and submits the PDCP PDU duplicates415a,415b, . . . to the configured RLC entities425a,425bassociated with the LCHs433(depicted as LCH1, LCH2, . . . ). It should be noted that the maximum number of PDCP PDU duplicates415a,415bwhich the UE500,605is supposed to transmit as configured by the NW may be smaller than the number of PDCP PDU duplicates generated respectively for the number of RLC entities/LCHs used for duplication as configured. In other words, a NW may configure a larger number of RLC entities/LCHs to be used for duplication than the number of PDCP duplicates which the UE500,605is allowed to transmit in order to support high reliability requirement for e.g., URLLC traffic in a shared spectrum.

Given that in a shared spectrum, the UE500,605needs to first get access to the channel before being able to make an uplink transmission, i.e., the UE500,605needs to perform channel sensing/LBT operation before an uplink transmission, it may happen that the transmission of a MAC PDU containing a PDCP duplicate415cannot take place due to an unsuccessful CCA (LBT failure) which in turn may impact the reliability. Therefore, the UE500,605may generate more PDCP duplicates415than are finally transmitted according to the NW configuration in accordance with this first embodiment and/or one or more compatible embodiments disclosed herein.

To give an example, the UE500,605may have a radio bearer configured for duplication with 4 RLC entities425, i.e., a PDCP entity410may be associated with one primary RLC425aand 3 secondary RLC entities425b. The NW may configure the UE500,605such that all four RLC entities425are used for duplication, i.e., a primary RLC entity425aand the three secondary RLC entities425b, such that 4 copies of a PDCP PDU415are generated. Furthermore, in certain implementations, the NW may configure the maximum number of PDCP duplicates the UE500,605is allowed to transmit to a value of 2. In order to ensure the transmission of two PDCP copies even in the case of LBT failures, the UE500,605generates according to this embodiment and compatible embodiments, four copies of a PDCP PDU415which are ready for transmission even though in the end only two of the four copies are transmitted in the uplink. According to one implementation of the embodiment, the UE500,605performs a LBT procedure for each of the uplink transmission of the four copies of the PDCP PDU415. In existing systems, an assumption for PDCP duplication introduced in Rel-16 has been that a configured grant is allocated for each of the RLC entities of a duplication bearer, i.e., data of an RLC entity/LCH of a duplication bearer is mapped to a configured grant.

According to various implementations of embodiment 1 and compatible embodiments, for cases when the LBT procedure is successful for the transmission of more than two PDCP PDU duplicates415, i.e., the number of successful LBTs is larger than maximum number of PDCP duplicates that the UE is allowed to transmit, the UE500,605selects according to one implementation of the embodiment, which of the PDCP duplicates415to transmit, and thereby which of the configured grant (“CG”) resources are used for transmission. Any remaining CG resource with successful LBTs can be skipped, or alternatively used for other transmissions by the UE500,605, e.g., for other PDUs or SDUs. According to another implementation of the embodiment, the NW may additionally configure the UE500,605with the RLC entities425and corresponding LCHs which are in certain embodiments used by the UE500,605for the transmission of PDCP duplicates415for the cases where the corresponding LBT is successful. According to one or more implementations of the first embodiment, the UE500,600transmits at most as many PDCP duplicates415as configured by the NW even though the UE500,605may have gotten access to the channel, i.e., the LBT was successful, for the transmission of further PDCP duplicates. The other generated MAC PDU(s) containing the further generated PDCP PDU duplicates which are not transmitted and are hence pending in the HARQ buffer of one or more HARQ entities445are discarded, according to one or more implementations of the first embodiment and compatible embodiments. Accordingly, there is no further (re)transmission of such MAC PDUs. Similarly, the corresponding RLC PDUs/PDCP PDUs respectively RLC SDUs/PDCP SDUs multiplexed in those MAC PDUs are also discarded according to certain implementations. Moreover, when discarding the RLC PDU/SDU(s), the UE500,605may reassign a Radio Link Control Sequence Number (“RLC SN”) of the subsequent RLC PDUs in order to avoid a Sequence Number (“SN”) gap to facilitate a RLC receiving window operation. Any remaining CG resource with a successful LBT may be skipped, or alternatively used for other transmissions by the UE500,600, e.g., for other PDUs or SDUs.

According to a second embodiment, a UE such as UE500,605autonomously activates (e.g., enables without receiving explicit duplication activation instructions from the network) RLC entities425and corresponding LCHs433for PDCP duplication, e.g., secondary LCH(s)433b, among the set of configured RLC entities425and corresponding LCHs433associated with a duplication radio bearer and submits PDCP PDU duplicates415to the autonomously activated RLC entities425. Essentially, the UE500,605generates more duplicates of a PDCP PDU415than configured by the NW entity. A radio bearer being configured for duplication may have a set of associated RLC entities425and corresponding LCHs433—the set of RLC entities425including a primary RLC entity425aand one or more secondary RLC entities425b, but only a subset of the RLC entities425is configured by the NW to be used for duplication. In order to support high reliability transmissions (e.g., URLLC), PDCP duplication may be required. However, given that in a shared spectrum, the UE500,605needs to first get access to the channel before being able to make an uplink transmission, i.e., the UE needs to perform LBT procedure before an uplink transmission, it may happen that the transmission of a MAC PDU containing a PDCP duplicate cannot take place due to a failed CCA, which, in turn will impact the reliability. Therefore, the UE500,605will, according to the second embodiment and one or more compatible embodiments, proactively generate more PDCP duplicates than are configured by the network in order to ensure that the configured number of duplicates is finally transmitted. The UE500,605duplicates, according to one implementation of the second embodiment, one or more PDCP SDU/PDU of a DRB configured for duplication at the PDCP transmitting entity and submits the one or more duplicate PDCP PDUs415bto a set of secondary RLC entities425band corresponding LCHs433b. It should be noted that the set of secondary RLC entities425bused for duplication is bigger than the number of duplicates configured by the NW.

To give an example, a UE500,605may have a radio bearer configured for duplication with four RLC entities, i.e., a PDCP entity410may be associated with one primary RLC and three secondary RLC entities. The network may configure the UE500,605such that only two of the four RLC entities are used for duplication, i.e., the primary RLC entity and one secondary RLC entity, such that two copies of a PDCP PDU are transmitted. In order to ensure the transmission of two PDCP copies, even in the case of LBT failures625, the UE500,605autonomously activates the remaining two secondary RLC entities425bfor duplication in order generate two more copies of a PDCP SDU/PDCP PDU415bwhich are ready for transmission in case of a LBT failure625. Accordingly, the UE500,605performs a LBT procedure615for uplink transmissions of the MAC PDUs containing PDCP PDUs of the two RLC entities425bconfigured by the NW for duplication as well as for transmission of the additional two PDCP PDU duplicates425bgenerated autonomously by the UE500,605.

In existing systems, an assumption for PDCP duplication introduced in Rel-16 has been that a configured grant is allocated for each of the RLC entities of a duplication bearer, i.e., data of a RLC entity/LCH of a duplication bearer is mapped to a configured grant. In case the LBT procedure is successful620for the transmission of the PDCP PDU copies of the two RLC entities configured by NW for duplication, the UE500,605transmits only the two corresponding MAC PDUs and discards the other two generated MAC PDUs pending for transmission as well as the corresponding RLC PDUs/PDCP PDUs contained in the MAC PDUs. For cases when LBT/CCA615fails for a transmission of a PDCP PDU of the two RLC entities configured by the NW for duplication and LBT/CCA is successful for the transmission of an autonomously generated PDCP PDU duplicate, the UE transmits the corresponding MAC PDU containing the autonomously generated PDCP PDU duplicates415bsuch that two PDCP PDU duplicates415bare transmitted. The other generated MAC PDUs are discarded as well as the corresponding RLC PDUs/PDCP PDUs contained in the MAC PDU. Further when discarding the untransmitted RLC PDU(s)415b, the UE500,605reassigns a RLC SN of the subsequent RLC PDUs in order to avoid a SN gap, i.e., as this is important for the RLC receiving window operation.

According to a third embodiment, which may be implemented in connection with the first and second embodiments described about, a UE500,605may transmit a TB containing a PDCP PDU duplicate415for which transmission could not take place in a HARQ process due to a failed LBT625in a different HARQ process being associated with a PUSCH for which an LBT was successful. As described in the first and second embodiments above, in order to support high reliability transmissions (URLLC) PDCP duplication is one technique which is used by the network. However, given that in a shared spectrum, the UE500,605needs to first get access to the channel before being able to make an uplink transmission, i.e., the UE500,605needs to perform a LBT procedure before an uplink transmission, it may happen that the transmission of a MAC PDU containing a PDCP duplicate cannot take place due to a failed LBT/CCA which in turn will impact the reliability. According to one implementation of this third embodiment, the NW configures which of the RLC entities/LCHs associated with the PDCP entity of a duplication bearer are to be used for PDCP duplication. The NW may only configure a subset of the configured RLC entities to be used for PDCP duplication. Accordingly, the UE500,605generates PDCP PDU duplicates and submits them to the configured RLC entities/LCHs. As in Rel-16, the UE performs an LBT procedure for the transmission of the corresponding MAC PDUs containing the PDCP PDU duplicates. According to one implementation of the embodiment, the UE500,605, however, performs not only an LBT procedure for the UL grant(s) for which those MAC PDUs have been generated, but may also perform LBT on other UL grant(s) which are available for transmission. Such additional UL grants may be for example the UL grants associated with the other RLC entities of the duplication bearer which are not enabled for duplication according to NW configuration.

As mentioned above it is expected that SPS and Configured Grants (CG) will play a key role in serving the various co-existing traffic types expected in TSN networks. As a result, it is assumed that TSN streams carrying delay-sensitive data, e.g., URLLC traffic, requiring the support of a survival time is mapped onto an UL DRB which is configured with duplication across two or more legs, where the duplication is inactive by default. The associated LCHs are e.g., mapped onto configured grants (e.g., via a LCP restriction parameter such as LCH carrier restrictions440) which are dimensioned such that the resources are well aligned with the data arrival time and also well dimensioned to carry a complete TSN message/PDCP SDU, so that RLC does not need to segment it.

In order to not delay the transmission of high priority packets such as PDCP PDU duplicates, which may not be acceptable for e.g., URLLC data, the UE500,605may transmit a generated MAC PDU—for cases that LBT fails for the associated UL grant—on a different UL grant for which LBT was successful. Assuming that the TB size is the same for the UL grants for which UE performed LBT procedure, the internal mapping of TB(s) to different HARQ processes should not impose any technical problems.

According to a fourth embodiment, a UE500,605selectively enables duplication for the transmission or retransmission of a MAC PDU containing a PDCP PDU415of a duplication bearer according to certain predefined criteria. In order to be able to transmit duplicate(s) of a PDCP PDU415afor which the original PDCP PDU415awas not transmitted due to a failed LBT625, i.e., an LBT that failed for the (re)transmission of the MAC PDU containing the original PDCP PDU415a, the duplicates of the original PDCP PDU415amust be already available for transmission. Therefore, the UE500,605duplicates, according to one implementation of the fourth embodiment, each PDCP SDU/PDU of a DRB configured for duplication at the PDCP transmitting entity and submits the duplicate(s) proactively to the one or more RLC entities425and corresponding logical channels433which are configured for PDCP duplication, i.e., also referred to as secondary LCHs. It should be noted that the duplication at the PDCP layer405is done even though duplicate transmissions are currently deactivated by NW, i.e., when PDCP PDUs are otherwise only transmitted via a single (primary) logical channel on PUSCH. According to one implementation UE selectively enables PDCP duplication for the transmission of PDCP PDUs of a radio bearer configured for duplication for cases that a MAC PDU containing a PDCP PDU of the radio bearer was not transmitted due to a failed LBT625, i.e., an LBT that failed for the (re)transmission of the MAC PDU containing the original PDCP PDU415. It should be noted that PDCP duplication is applied to the subsequent PDCP PDUs of the radio bearer.

According to one or more implementations of this fourth embodiment, a UE500,605pre-generates one or more duplicate RLC PDUs upon receiving the duplicate PDCP PDUs from the PDCP transmitting entity at the RLC entity(ies)425associated with the one or more secondary LCHs433and stores the pre-generated RLC PDUs427at the respective RLC entities425, i.e., store the RLC PDUs427that are pending for initial transmission. Generating an RLC PDU427implies that an RLC SN is associated with the PDCP PDU/RLC SDU received from PDCP layer405and a RLC header is generated (e.g., as further specified in 3GPP TS 38.322).

When pre-generating the one or more RLC PDUs, the UE500,605may assume that no segmentation is needed, i.e., that a complete PDCP PDU415is contained in one RLC PDU. According to this implementation of the fourth embodiment, the UE500,605discards the pre-generated RLC PDUs427of the secondary LCHs upon receiving an acknowledgement635from lower layers that an LBT was successful for the transmission of a MAC PDU containing the original PDCP PDU415carried on the (primary) LCH. By discarding the duplicate RLC PDUs427stored at the RLC layer420for the secondary LCH(s)433, it is ensured that a duplication transmission is not performed for cases that the transmission of a PDCP PDU415was performed, i.e., LBT/CCA success, on the primary LCH. Hence a wastage of radio resources is avoided by discarding640duplicate RLC PDUs based on feedback635of LBT success.

Further, when discarding the pre-generated (but untransmitted) duplicate RLC PDUs427b, the UE500,605may reassigns the RLC SN of the subsequent RLC PDUs427in order to avoid a SN gap, i.e., this is important for the RLC receiving window operation. Upon receiving feedback from lower layers that LBT failed for the transmission of a MAC PDU carrying a PDCP PDU415of the primary LCH433, the UE500,605autonomously enables transmission of the pre-generated duplicate PDCP/RLC PDU(s) and optionally for further subsequent PDCP PDU transmissions according to one implementation of the fourth embodiment. To be more specific, when UE500,605receives a LBT failure indication for the (initial) transmission of a MAC PDU containing an original PDCP/RLC PDU of the primary LCH, the UE performs a retransmission of this MAC PDU (carrying the data of the primary LCH), e.g., autonomous retransmission for the case that LBT failed for a configured grant transmission, and also in addition transmits the pre-generated RLC PDU(s) containing the duplicate PDCP PDU(s) for the secondary LCH(s) which are pending in the RLC layer for initial transmission.

The UE500,605submits the pre-generated RLC PDUs to the MAC layer where corresponding MAC PDUs are generated and ultimately transmitted on the PUSCH(s), e.g., duplicates may be transmitted on other configured grants being scheduled/assigned for duplicate transmissions. The MAC PDU(s) containing the duplicated PDCP PDU(s) are for example transmitted with redundancy version (RV) zero or any other RV which ensures that the transmissions are self-decodable.

As mentioned above, it is expected that SPS and Configured Grants (CG) will play a key role in serving the various co-existing traffic types expected in TSN networks. As a result, it is assumed that TSN streams carrying delay-sensitive data, e.g., URLLC traffic, requiring the support of a survival time is mapped onto an UL DRB which is configured with duplication across two or more RLC entities425and corresponding LCHs433. The associated LCHs433are e.g., mapped onto configured grants (e.g., via LCP restriction parameters440) dimensioned such that the resources are well aligned with the data arrival time and also well dimensioned to carry a complete TSN message/PDCP SDU, so that RLC does not need to segment it.

According to a further embodiment, the UE500,605receives configuration information that includes a priority threshold, which determines whether to apply the enhanced duplication schemes as outlined in various of the disclosed embodiments. For example, for cases when a bearer configured for duplication has an associated logical channel priority exceeding (alternatively being greater or equal) the configured threshold, the UE500,605is allowed to apply some proactive generation of PDCP PDU duplicates415as outlined in the second embodiment or may transmit MAC PDUs containing PDCP PDU duplicates415on other UL resources than configured by NW as outlined in the third embodiment. Alternatively, the NW may explicitly configure for a bearer whether the enhanced duplication mechanisms as outlined in any of the disclosed embodiments are to be applied by the UE505,605.

According to a fifth embodiment, a UE500,605discards a MAC PDU containing a PDCP PDU (duplicate)415which is pending in a HARQ buffer (e.g., in HARQ entities445) for (re)transmission in case the successful decoding/transmission of another MAC PDU containing copy of the same PDCP PDU415was acknowledged by the receiver. The MAC PDU may be for example pending in a HARQ buffer due to a failed LBT for a transmission attempt. According to this implementation of the embodiment, the UE500,605discards the MAC PDU containing a PDCP PDU duplicate415upon receiving an acknowledgement (ACK) from receiving entity for the transmission of another MAC PDU containing a copy of the same PDCP PDU415.

In order to be able to discard the MAC PDU, the UE500,605/MAC layer430may need to check the PDCP SN of the PDCP PDU415contained in a MAC PDU, i.e., MAC layer430needs to parse the higher layer header. According to a further implementation, the UE500,605further discards the duplicate PDCP PDU415and corresponding RLC SDU/RLC PDU427. By discarding the duplicate PDUs stored at the RLC layer420and the PDCP layer405, it is ensured that a duplication transmission is not performed for cases that the transmission of the PDCP PDU415was already performed successfully. Hence a wastage of radio resources is avoided by discarding duplicate RLC/MAC PDUs based on HARQ feedback from the receiving entity. Further when discarding duplicate RLC SDU/PDUs, the UE500,605reassigns the RLC SN of the subsequent RLC PDUs427in order to avoid a SN gap, i.e., this is important for the RLC receiving window operation.

According to a sixth embodiment, a UE500,605increases the channel access priority class, i.e., adopts a lower channel access priority class value, for the next transmission attempt of the same MAC PDU in case the previous transmission attempt was not successful, i.e., when the MAC PDU could not be transmitted on PUSCH due to a LBT failure. If for example a channel access priority class of value 3 was used for a transmission attempt, then UE500,605may according to this embodiment use the channel access priority class of value ‘2’ for the next transmission attempt of the same TB. According to another implementation of this embodiment, the UE500,605may use a short LBT for a next transmission attempt of a MAC PDU for cases that LBT failed for the previous transmission attempt. Increasing the Channel Access Priority Class (“CAPC”) or using only short LBT may increase the probability of a LBT success for the next transmission attempt, which may be important in order to avoid for example a situation where survival time245expires.

Especially at higher carrier frequencies, multiple beams may operate nominally on the same cell, where the spatial characteristic of each beam can ensure that there is little correlation of the channel characteristics, thereby enabling another degree of diversity. It is therefore possible in all disclosed embodiments that the cell restriction functionality (described above in the context of CA/DC duplication LCH carrier restrictions440) does not need to be upheld. For example, duplicated packets may be transmitted on the same cell with different beams. To this end, exemplarily a respective CG resource can be configured with a spatial relation information (representing a beam, for example, using a TCI index/SRI index). Additional configuration information may indicate which of the spatial relations (representing a beam) is used for the transmission of an LCH associated with a duplication radio bearer.

In certain embodiments, the apparatuses, systems, and methods disclosed herein provide enhanced PDCP duplication operation in a shared spectrum. In such embodiments, a NW configures/activates ‘n’ RLC entities/LCHs of a duplication bearer which are used for PDCP duplication, i.e., the UE generates n PDCP duplicates. The NW further configures ‘x’, the maximum number of duplicates to be transmitted by the UE, where x<n.

Further, the UE performs an LBT procedure for all n MAC PDUs carrying the n PDCP duplicates. If the number of successful LBT is larger than x, then the UE selects which PDCP duplicates to transmit.

In some embodiments, a UE autonomously activates RLC entities/LCH of a duplication for PDCP duplication. In such embodiments, the UE autonomously generates additional PDCP duplicates (NW configured the UE to generate a certain number of duplicates) and performs LBT procedure for the transmission of the corresponding MAC PDUs in order to increase the probability of LBT success for the configured number of PDCP duplicates.

In various embodiments, a UE autonomously activates PDCP duplication for cases when LBT fails for the transmission of the original PDCP PDU. In such embodiments, the UE pre-generates PDCP duplicates which are ready for transmission in case of LBT failure and the UE discards the pre-generated PDCP duplicates in a case in which LBT success is indicated for the transmission of the original PDCP PDU.

In certain embodiments, a UE increases the CAPC for cases when LBT fails for the transmission on a configured grant in order to increase the likelihood of a LBT success for the autonomous retransmission of the TB.

FIG.7depicts one embodiment of a network equipment apparatus700that may be used for configuring duplication of PDCP PDUs for a radio bearer, according to one or more embodiments of the disclosure. The network equipment apparatus700may be an instance of the base unit110and/or the gNB610(described with respect toFIGS.1and6. Furthermore, the network equipment apparatus700may include a processor705, a memory710, an input device715, an output device720, and a transceiver725. In some embodiments, the input device715and the output device720are combined into a single device, such as a touch screen. In certain embodiments, the network equipment apparatus700does not include any input device715and/or output device720.

As depicted, the transceiver725includes at least one transmitter730and at least one receiver735. Additionally, the transceiver725may support at least one network interface770. Here, the at least one network interface740facilitates communication with a remote unit105, such as the UE500,605, with other network functions in a mobile core network140, such as the UPF141, AMF143, and the like.

The processor705, in one or more embodiments, may include any known controller capable of executing computer-readable instructions and/or capable of performing logical operations. For example, the processor705may be a microcontroller, a microprocessor, a central processing unit (“CPU”), a graphics processing unit (“GPU”), an auxiliary processing unit, a field programmable gate array (“FPGA”), or similar programmable controller. In some embodiments, the processor705executes instructions stored in the memory710to perform the methods and routines described herein. The processor705is communicatively coupled to the memory710, the input device715, the output device720, and the transceiver725.

In certain embodiments, the network equipment apparatus700may be involved in performance of various steps of UE methods for selectively (e.g., autonomously) enabling PDCP duplication such as for example, communication configuration information to the UE indicating the number of duplicate PDCP PDUs that may be generated or communication other configuration information described above.

FIG.8is a flow chart diagram illustrating one embodiment of a method800that may be used for increasing the transmission reliability for transmissions of a duplication bearer in a shared or unlicensed spectrum.

In certain embodiments, the method800is performed by a user equipment device (“UE”). In one or more embodiments, the method800includes receiving802a configuration from a network entity configuring the RLC entities of a split bearer configured for PDCP duplication a PDCP PDU of said split bearer is submitted to. In certain embodiments, method800continues and includes receiving804a configuration from the network entity configuring the maximum number of duplicates to be transmitted for a PDCP PDU. In some embodiments, method800continues and includes generating806a PDCP PDU duplicate of a PDCP PDU for each of the configured RLC entities of said split bearer and submitting a PDCP duplicate to each of the configured RLC entities. In various embodiments, the method800continues and includes initiating808a listen before talk procedure on a shared or unlicensed spectrum, for the transmission resource associated with each of the generated PDCP PDU duplicates. In certain embodiments, the method800continues and includes determining810whether the listen before talk procedure was successful or not for the transmission resource of a PDCP PDU duplicate. In some embodiments, the method800continues and includes transmitting812a PDCP PDU duplicate if the listen before talk procedure was successful and the number of transmitted PDCP PDU duplicates for a PDCP PDU has not exceeded said configured maximum number of duplicates and the method800ends.

In some embodiments, the number of configured RLC entities a PDCP PDU duplicate is submitted to is greater than the configured maximum number of duplicates.

In certain embodiments, the UE forms a MAC PDU for each of the PDCP PDU duplicate submitted to the configured RLC entities, said MAC PDU being comprised of a PDCP PDU duplicate.

In various embodiments, the method800and/or various implementations thereof may be implemented using the remote unit105depicted inFIG.2of the present disclosure.

FIG.9is a flow chart diagram illustrating another method900that may be used for selectively enabling PDCP duplication for a data radio bearer in a network that supports shared spectrum, in accordance with one or more embodiments of the disclosure.

In various embodiments, the method900begins and includes initiating905a listen before talk procedure (“LBT”) on shared spectrum, for a transmission of a medium access control (“MAC”) protocol data unit (“PDU”) containing an original packet data convergence protocol (“PDCP”) PDU of a data radio bearer (“DRB”) configured for PDCP duplication, where PDCP duplication is deactivated for the data radio bearer. The method900continues and further includes determining910whether the LBT failed or succeeded. The method900continues and further includes selectively enabling915PDCP duplication for the data radio bearer configured for duplication in response to determining that the PDCP PDU was not transmitted due to failure of the LBT.

In various embodiments, the apparatuses, systems, and methods disclosed herein, provide a useful aspect of enabling an enhanced PDCP duplication operation in a shared or unlicensed spectrum by reducing the impact of LBT failures for the transmission of PDCP duplicates for reliability and latency critical URLLC traffic. A second aspect is to autonomously enable PDCP duplication in the event of an LBT failure in order to avoid that the survival timer associated with a bearer expires.

In some embodiments, a NW configures the UE to generate a higher number of PDCP duplicates than the number of duplicates which UE is ultimately allowed to transmit in the uplink to the receiver. By generating a higher number of PDCP duplicates and performing LBT procedure for all the generated PDCP duplicates respectively the MAC PDU carrying such PDCP duplicates, the probability of LBT success for the number of duplicates the UE is ultimately transmitting is increased. By autonomously enabling PDCP duplication in the UE for the case that LBT failed for a transmission attempt of a packet increases the probability that the packet is successfully transmitted within the required delay budget.

The various embodiments disclosed herein provide certain advantages over other implementations that rely on autonomous retransmissions for the case that an LBT failure occurred for the transmission of a PDCP PDU duplicate, which increases the latency of a data packet transmission and may even cause the expiry of a survival timer trigger the application to transition the status of the communication service into a down state. By enabling autonomously PDCP duplication for cases when LBT failed for a previous transmission attempt of a packet or by increasing the number of LBT trials for the transmission of PDCP duplicates, the transmission reliability is increased and the latency for a packet transmission is reduced.

In one aspect, a UE generates a configured number of PDCP duplicates and performs LBT procedure for the transmission of the corresponding MAC PDUs carrying the PDCP PDU duplicates. The UE transmits only a subset of the generated PDCP duplicates/MAC PDUs for which LBT procedure was successful. NW configures the UE with the maximum of duplicates which the UE is allowed to transmit; the other PDCP duplicates/MAC PDUs are discarded.

In another aspect, a UE autonomously pre-generates duplicates of a PDCP PDU and submits them to the configured RLC entities of a duplication bearer. When LBT fails for the transmission of a PDCP PDU, the UE autonomously generates MAC PDU carrying the pre-generated PDCP duplicates and performs LBT procedure for such MAC PDUs in a subsequent transmission occasion.

A User Equipment (“UE”) apparatus for a mobile network (“NW”) is disclosed that includes a transceiver that initiates a listen before talk procedure (“LBT”) on shared spectrum, for a transmission of a medium access control (“MAC”) protocol data unit (“PDU”) containing an original packet data convergence protocol (“PDCP”) PDU of a data radio bearer (“DRB”) configured for PDCP duplication, wherein PDCP duplication is deactivated for the data radio bearer. In various embodiments, the apparatus includes a processor that: determines whether the LBT failed or succeeded; and selectively enables PDCP duplication for the data radio bearer configured for duplication in response to determining that the PDCP PDU was not transmitted due to failure of the LBT.

In some embodiments, prior to performing the LBT, the UE duplicates the original PDCP PDU and submits duplicate PDCP PDUs to one or more RLC entities associated with a PDCP entity of the data radio bearer and corresponding logical channels (“LCHs”) selected from a primary LCH and one or more secondary LCHs.

In certain embodiments, the UE duplicates the original PDCP PDU whether or not duplicate transmissions are currently deactivated by the NW.

In various embodiments in response to receiving duplicate PDCP PDUs from a PDCP transmitting entity at the one or more RLC entities, the UE pre-generates and stores corresponding RLC PDUs at the one or more RLC entities pending a transmission of the duplicates.

In one or more embodiments, UE pre-generates the corresponding RLC PDUs without segmentation such that each PDCP PDU is contained in one RLC PDU.

In some embodiments, in response to receiving feedback from lower layers that an LBT failed for the transmission of the MAC PDU containing the original PDCP PDU carried on the primary LCH, the UE retransmits the MAC PDU containing the original PDCP PDU on the primary LCH and transmits the pre-generated RLC PDUs stored at the RLC entities corresponding to one or more secondary LCHs.

In various embodiments, in response to receiving an acknowledgement from lower layers that an LBT succeeded for the transmission of a MAC PDU containing the original PDCP PDU corresponding to the primary LCH, the UE discards the RLC PDUs stored at the RLC entities corresponding to the one or more secondary LCHs.

In certain embodiments, the UE reassigns an RLC sequence number (“SN”) of subsequent RLC PDUs to avoid a SN gap being caused by discarding pending duplicate RLC PDUs that were not transmitted.

In one or more embodiments, the UE further submits the pre-generated RLC PDUs to the MAC layer and generates MAC PDUs containing the duplicated PDCP PDUs for transmission on one or more physical uplink shared channels (“PUSCHs”).

In some embodiments, generated MAC PDUs are transmitted with a redundancy version that ensures that the transmissions are self-decodable.

In various embodiments, prior to selectively enabling PDCP duplication of the original PDCP PDU in response to determining that the PDCP PDU was not transmitted due to failure of the LBT, the UE receives configuration information including a priority threshold that indicates which of one or more predetermined duplication modes to use.

In certain embodiments, in response to receiving an acknowledgement of successful transmission and decoding of a MAC PDU containing the same PDCP PDU that was duplicated, the UE discards a copy of the MAC PDU pending in a HARQ buffer for transmission.

In one or more embodiments, the UE further discards one or more corresponding duplicate PDCP PDUs and RLC PDUs pending in a HARQ buffer for transmission based on HARQ feedback from a receiving entity.

In various embodiments, the UE reassigns an RLC sequence number (“SN”) of subsequent RLC PDUs to avoid a SN gap being caused by discarding the pending duplicate RLC PDUs that were not transmitted.

In some embodiments, in response to determining that the transmission of the MAC PDU containing the original PDCP PDU was unsuccessful due to an LBT failure, the UE performs one or more of:adopting a lower channel access priority class value for subsequent retransmission attempts of one or more MAC PDUs carrying the PDCP PDU duplicates; andusing a short LBT for subsequent retransmission attempts of one or more MAC PDUs carrying the PDCP PDU duplicates.

A method is disclosed for increasing transmission reliability for transmissions of a duplication bearer in a network (“NW”) that supports shared spectrum. In various embodiments, the method includes initiating a listen before talk procedure (“LBT”) on shared spectrum, for a transmission of a medium access control (“MAC”) protocol data unit (“PDU”) containing an original packet data convergence protocol (“PDCP”) PDU of a data radio bearer (“DRB”) configured for PDCP duplication, where PDCP duplication is deactivated for the data radio bearer. The method further includes determining whether the LBT failed or succeeded and selectively enabling PDCP duplication for the data radio bearer configured for duplication in response to determining that the PDCP PDU was not transmitted due to failure of the LBT.

In some embodiments, the method includes duplicating the original PDCP PDU prior to performing the LBT and submitting duplicate PDCP PDUs to one or more RLC entities associated with a PDCP entity of the data radio bearer and corresponding logical channels (“LCHs”) selected from a primary LCH and one or more secondary LCHs.

In one or more embodiments, the method includes duplicating the original PDCP PDU is performed whether or not duplicate transmissions are currently deactivated by the NW.

In certain embodiments, the method includes, in response to receiving duplicate PDCP PDUs from a PDCP transmitting entity at the one or more RLC entities, pre-generating and storing corresponding RLC PDUs at the one or more RLC entities pending a transmission of the duplicates.

In some embodiments, the method includes pre-generating the corresponding RLC PDUs without segmentation such that each PDCP PDU is contained in one RLC PDU.

In various embodiments, in response to receiving feedback from lower layers that an LBT failed for the transmission of the MAC PDU containing the original PDCP PDU carried on the primary LCH, the UE retransmits the MAC PDU containing the original PDCP PDU on the primary LCH and transmits the pre-generated RLC PDUs stored at the RLC entities corresponding to one or more secondary LCHs.

In one or more embodiments, in response to receiving an acknowledgement from lower layers that an LBT succeeded for the transmission of a MAC PDU containing the original PDCP PDU corresponding to the primary LCH, the UE discards the RLC PDUs stored at the RLC entities corresponding to the one or more secondary LCHs.

In certain embodiments, the UE reassigns an RLC sequence number (“SN”) of subsequent RLC PDUs to avoid a SN gap being caused by discarding pending duplicate RLC PDUs that were not transmitted.

In some embodiments, the UE submits the pre-generated RLC PDUs to the MAC layer and generates MAC PDUs containing the duplicated PDCP PDUs for transmission on one or more physical uplink shared channels (“PUSCHs”).

In various embodiments, the method includes transmitting the generated MAC PDUs with a redundancy version that ensures that the transmissions are self-decodable.

In one or more embodiments, the method includes receiving at a UE performing the transmissions configuration information comprising a priority threshold that indicates which of one or more predetermined duplication modes to use, wherein the configuration information is received prior to selectively enabling PDCP duplication of the original PDCP PDU in response to determining that the PDCP PDU was not transmitted due to failure of the LBT.

In certain embodiments, the method includes discarding a copy of the MAC PDU pending in a HARQ buffer for transmission in response to receiving an acknowledgement of successful transmission and decoding of a MAC PDU containing the same PDCP PDU that was duplicated.

In some embodiments, the method includes discarding one or more corresponding duplicate PDCP PDUs and RLC PDUs pending in the HARQ buffer for transmission based on HARQ feedback from a receiving entity.

In various embodiments, the method includes reassigning a RLC sequence number (“SN”) of subsequent RLC PDUs to avoid a SN gap being caused by discarding the pending duplicate RLC PDUs that were not transmitted.

In one or more embodiments, the method includes, in response to determining that the transmission of the MAC PDU containing the original PDCP PDU was unsuccessful due to an LBT failure, performing one or more of:adopting a lower channel access priority class value for subsequent retransmission attempts of one or more MAC PDUs carrying the PDCP PDU duplicates; andusing a short LBT for subsequent retransmission attempts of one or more MAC PDUs carrying the PDCP PDU duplicates.