TECHNIQUES TO FACILITATE PRIORITIZING PACKET DATA CONVERGENCE PROTOCOL (PDCP) PROTOCOL DATA UNITS IN DUAL CONNECTIVITY

Apparatus, methods, and computer-readable media for facilitating prioritizing PDCP retransmission and/or control information in dual connectivity scenarios are disclosed herein. An example method for wireless communication at a first network node includes receiving PDUs for transmitting to a second network node while operating in a dual connectivity mode associated with a first RLC leg and at least a second RLC leg, the PDUs associated with at least one of control information or retransmission data. The example method also includes transmitting first scheduling information via the first RLC leg and transmitting second scheduling information via the second RLC leg based on the PDUs being associated with at least one of the control information or the retransmission data. The example first network node may include a UE or a base station.

TECHNICAL FIELD

The present disclosure relates generally to communication systems, and more particularly, to wireless communication utilizing dual connectivity.

INTRODUCTION

BRIEF SUMMARY

In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided for wireless communication at a first network node. An example apparatus receives protocol data units (PDUs) for transmitting to a second network node while operating in a dual connectivity mode associated with a first radio link control (RLC) leg and at least a second RLC leg, the PDUs associated with at least one of control information or retransmission data. The example apparatus also transmits first scheduling information via the first RLC leg and transmitting second scheduling information via the second RLC leg based on the PDUs being associated with at least one of the control information or the retransmission data.

DETAILED DESCRIPTION

The aspects disclosed herein provide techniques for improved transmission at a PDCP entity. A PDCP entity of a transmitting device may receive data for transmitting to a PDCP entity of a receiving device. When the transmitting device and the receiving device are operating in a dual connectivity mode, they may establish a primary RLC leg with a primary RLC entity and one or more secondary RLC legs with one or more secondary RLC entities for transmitting the data from the transmitting device PDCP entity to the receiving device PDCP entity.

In some examples, the transmitting device PDCP entity may use a data split threshold volume to determine which RLC entity to use to transmit the data. For example, when the data to transmit is greater than or equal to the data split threshold volume, the transmitting device PDCP entity may transmit a scheduling request requesting a grant to transmit data on each of the RLC entities. However, when the data to transmit is less than the data split threshold volume, the transmitting device PDCP entity may transmit a scheduling request using the primary RLC entity and forego transmitting a scheduling request using the second RLC entity.

In some examples, however, the PDCP to be transmitted may be associated with higher priority transmissions. For example, the higher priority transmission may include control information, such as a status report, a robust header compression (ROHC) feedback, or Ethernet header compression (EHC) feedback. In some examples, the high priority data may include retransmission data. When the PDCP for transmission is associated with certain types of information, such as higher priority data, it may be beneficial to attempt to transmit the data to the receiving device PDCP entity with a best effort. In some aspects, the best effort may include attempting to transmit using more than the primary RLC leg. For example, a UE may transmit a scheduling request for the primary RLC leg and at least one secondary RLC leg, e.g., even if the volume is below a data split threshold volume.

Aspects disclosed herein provide techniques for transmitting high priority data from a transmitting device PDCP entity to a receiving device PDCP entity with a best effort to deliver the higher priority data while limiting delay of the data transmission. For example, when the transmitting device PDCP entity has control information or a PDCP retransmission to transmit, the transmitting device PDCP entity transmits a scheduling request on each of the RLC legs. When the data for transmitting is non-high priority data (e.g., does not include control information or PDCP retransmission), the transmitting device PDCP entity may transmit a scheduling request on each of the RLC legs when the data volume of the data for transmitting satisfies the data split threshold volume, or may transmit a scheduling request on the primary RLC leg when the data volume of the data for transmitting fails to satisfy the data split threshold volume.

The aspects presented herein may enable a transmitting device to transmit higher priority data, such as control information or a PDCP retransmission, with a best effort while operating in a dual connectivity mode, for example, by transmitting the higher priority data using whichever RLC leg that provides a grant first and irrespective of a relationship between the volume of the higher priority data and the data split threshold volume.

FIG.1is a diagram illustrating an example of a wireless communications system and an access network100including base stations102and180and UEs104. In certain aspects, a device in communication with a base station, such as a UE104, may be configured to manage one or more aspects of wireless communication by facilitating transmitting of PDUs while operating in a dual connectivity mode. For example, the UE104may include a UE prioritization component198configured to receive PDUs for transmitting to a second network node (e.g., the base stations102and180) while operating in a dual connectivity mode associated with a first RLC leg and at least a second RLC leg, the PDUs associated with at least one of control information or retransmission data. The example UE prioritization component198may also be configured to transmit first scheduling information via the first RLC leg and transmitting second scheduling information via the second RLC leg based on the PDUs being associated with at least one of the control information or the retransmission data.

In another configuration, a base station, such as the base stations102and180, may be configured to manage or more aspects of wireless communication by facilitating transmitting of PDUs while operating in a dual connectivity mode. For example, the base stations102/180may include a base station prioritization component199configured to receive PDUs for transmitting to a second network node (e.g., the UE104) while operating in a dual connectivity mode associated with a first RLC leg and at least a second RLC leg, the PDUs associated with at least one of control information or retransmission data. The example base station prioritization component199may also be configured to transmit first scheduling information via the first RLC leg and transmitting second scheduling information via the second RLC leg based on the PDUs being associated with at least one of the control information or the retransmission data.

The aspects presented herein may enable a transmitting device to transmit high priority data with a best effort while operating in a dual connectivity mode, for example, by transmitting the high priority data using whichever RLC leg that provides a grant first and irrespective of a relationship between the volume of the high priority data and the data split threshold volume.

Although the following description provides examples directed to 5G NR (and, in particular, to transmissions while operating in a dual connectivity mode), the concepts described herein may be applicable to other similar areas, such as LTE, LTE-A, CDMA, GSM, and/or other wireless technologies, in which a network node may receive high priority data and non-high priority data for transmitting while operating in a dual connectivity mode.

FIG.3is a block diagram that illustrates an example of a first wireless device that is configured to exchange wireless communication with a second wireless device. In the illustrated example, the first wireless device may include a base station310, the second wireless device may include a UE350, and the base station310may be in communication with the UE350in an access network. As shown inFIG.3, the base station310includes a transmit processor (TX processor316), a transceiver318including a transmitter318aand a receiver318b, antennas320, a receive processor (RX processor370), a channel estimator374, a controller/processor375, and memory376. The example UE350includes antennas352, a transceiver354including a transmitter354aand a receiver354b, an RX processor356, a channel estimator358, a controller/processor359, memory360, and a TX processor368. In other examples, the base station310and/or the UE350may include additional or alternative components.

The UL transmission is processed at the base station310in a manner similar to that described in connection with the receiver function at the UE350. Each receiver318breceives a signal through its respective antenna320. Each receiver318brecovers information modulated onto an RF carrier and provides the information to the RX processor370.

FIG.4Aillustrates an example environment400supporting dual connectivity, as presented herein. Dual connectivity allows a UE404to receive data simultaneously from and/or transmit data simultaneously to different base stations (e.g., a primary base station402and a secondary base station406) in order to boost the performance of a communication link. The primary base station402and the secondary base station406may be connected via a backhaul interface.

FIG.4Billustrates an example protocol stack420for dual connectivity at a network, as presented herein. In the example ofFIG.4B, the network is implemented by the primary base station402(sometimes referred to as a “master base station,” a “primary cell group” or a “master cell group”) and the secondary base station406ofFIG.4A. However, other examples may include any suitable quantity of base stations. Additionally, or alternatively, dual connectivity at the network may be implemented by a same base station providing different cells (e.g., a primary cell and one or more secondary cells). In the example ofFIG.4B, the protocol stack420may include a PDCP entity422, a first RLC entity424, and a first MAC entity426associated with the primary base station402. The protocol stack420also includes a second RLC entity428and a second MAC entity430associated with the secondary base station406. In dual connectivity, the PDCP entity422associated with the primary base station402may receive a packet from a higher entity or layer for transmitting to the UE404. The PDCP entity422may transmit the packet via the first RLC entity424or the second RLC entity428.

FIG.4Cillustrates an example protocol stack440for dual connectivity at a UE, as presented herein. In the example ofFIG.4C, the UE is implemented by the UE404ofFIG.4A. The protocol stack440includes a PDCP entity442, a first RLC entity444, a second RLC entity446, and a MAC entity448. In some examples, the protocol stack440may include any number of RLC entities (e.g., two, three, four, five, etc.). In the illustrated example, the MAC entity448may service more than one RLC entity. However, in other examples, the protocol stack440may include any suitable quantity of MAC entities to service the RLC entities.

In the examples ofFIG.4BandFIG.4C, the PDCP entities provide multiplexing between different radio bearers and logical channels. The PDCP entities also provide header compression for upper layer data packets to reduce radio transmission overhead, security by ciphering the data packets, and handover support for UEs between base station. The RLC entities provide segmentation and reassembly of upper layer data packets, retransmission of lost data packets, and reordering of data packets to compensate for out-of-order reception due to hybrid automatic repeat request (HARQ). The MAC entities provide multiplexing between logical and transport channels. The MAC entities may also be responsible for allocating the various radio resources (e.g., resource blocks) in one cell among the UEs. The MAC entities may also be responsible for HARQ operations.

Referring again to the example ofFIG.4A, the UE404establishes dual connectivity with a network by establishing connections with the primary base station402and the secondary base station406. In the illustrated example, the UE404may establish a first connection path (e.g., a primary RLC leg408) with the primary base station402. The UE404may also establish a second connection path (e.g., a secondary RLC leg410) with the secondary base station406. For example, the primary RLC leg408may correspond to a connection between the first RLC entity444of the UE404and the first RLC entity424of the primary base station402. The secondary RLC leg410may correspond to a connection between the second RLC entity446of the UE404and the second RLC entity428of the secondary base station406.

While operating in the dual connectivity mode, the UE404may use the primary RLC leg408and/or the secondary RLC leg410to transmit data. However, the UE404may be configured with an uplink data split threshold (e.g., which may be referred to as an “ul-DataSplitThreshold” parameter or by any other name) that may indicate when and how to split the data for transmitting. For example, the UE404may be configured with an uplink data split threshold of 100 bytes. In some examples, if the overall data volume for transmitting is less than the uplink data split threshold (e.g., less than 100 bytes), then the UE404transmits the data via the primary RLC leg408. If the overall data volume is greater than or equal to the uplink data split threshold (e.g., greater than or equal to 100 bytes), then the secondary RLC leg410may also transmit a portion of the data.

However, in some examples, the RLC legs may experience different channel conditions. In such examples, if the channel conditions for each RLC leg are not considered when transmitting data, then the UE404may not take full advantage of the dual connectivity.

The aspects presented herein may enable a transmitting device to transmit certain types of information, such as higher priority transmissions, with a best effort while operating in a dual connectivity mode, for example, by transmitting the higher priority transmissions using whichever RLC leg that provides a grant first and irrespective of a relationship between the volume of the PDCP for transmission and the data split threshold volume. As examples of PDCP transmissions that may be considered high priority, the transmitting device may attempt to transmit with a best effort for PDCP retransmissions or control transmissions.

FIG.5illustrates an example communication flow500between a transmitting PDCP entity504and a receiving PDCP entity502, as presented herein. In the illustrated example, the communication flow500facilitates the transmitting of high priority data while operating in dual connectivity with a best effort to deliver the high priority data with reduced delay. As described herein, high priority data may include retransmission data and/or control information. In some examples, the transmitting PDCP entity504may be part of a UE, such as the example UE104ofFIG.1and/or the UE350ofFIG.3, and the receiving PDCP entity502may be part of a base station, such as the base station102/180ofFIG.1and/or the base station310ofFIG.3. In other examples, the transmitting PDCP entity504may be part of a base station, such as the base station102/180ofFIG.1and/or the base station310ofFIG.3, and the receiving PDCP entity502may be part of a UE, such as the example UE104ofFIG.1and/or the UE350ofFIG.3. Although not shown in the illustrated example ofFIG.5, in additional or alternative examples, the transmitting PDCP entity504may be in communication with one or more other base stations or UEs, and/or the receiving PDCP entity502may be in communication with one or more other base stations or UEs.

As shown inFIG.5, the transmitting PDCP entity504may be configured with a data split threshold volume508. In the illustrated example ofFIG.5, the transmitting PDCP entity504is configured with a data split threshold volume508of 500 bytes. However, other examples may include any suitable data volume. Moreover, when the transmitting PDCP entity504is part of a UE, the data split threshold volume may correspond to an uplink data split threshold volume, which may be referred to as “ul-DataSplitThreshold” or by any other name. When the transmitting PDCP entity is part of a base station, the data split threshold volume may correspond to any conditional threshold volume associated with one or more of the RLC legs.

In the illustrated example ofFIG.5, the transmitting PDCP entity504is operating in a dual connectivity mode with the receiving PDCP entity502. For example, the transmitting PDCP entity504includes a primary transmitting RLC entity504aand a secondary transmitting RLC entity504b, and the receiving PDCP entity502includes a primary receiving RLC entity502aand a secondary receiving RLC entity502b. As shown inFIG.5, the transmitting PDCP entity504and the receiving PDCP entity502establish a primary RLC leg510. For example, the primary transmitting RLC entity504aand the primary receiving RLC entity502amay establish a connection. Aspects of the primary RLC leg510may be implemented by the primary RLC leg408ofFIG.4A. The transmitting PDCP entity504and the receiving PDCP entity502may also establish a secondary RLC leg512. For example, the secondary transmitting RLC entity504band the secondary receiving RLC entity502bmay establish a connection. Aspects of the secondary RLC leg512may be implemented by the secondary RLC leg410ofFIG.4A.

FIG.5includes a table590including a time column592indicating a time, and a data volume column594indicating a volume of data for transmitting at the transmitting PDCP entity504at a respective time. The example table590also includes a primary leg transmission window column596and a secondary leg transmission window column598. The primary leg transmission window column596indicates a PDCP count of packets transmitted using the primary RLC leg510(e.g., transmitted from the primary transmitting RLC entity504ato the primary receiving RLC entity502a). The secondary leg transmission window column598indicates a PDCP count of packets transmitted using the secondary RLC leg512(e.g., transmitted from the secondary transmitting RLC entity504bto the secondary receiving secondary receiving RLC entity502b).

As shown inFIG.5, the transmitting PDCP entity504receives, at514, PDUs for transmitting to the receiving PDCP entity502. The PDUs may include data packets and/or control packets. For example, the transmitting PDCP entity504may receive ten packets (e.g., packets 0 to 9) for transmitting, and each packet may be 100 bytes in size. As shown in the table590, at a time T0, which corresponds to after the transmitting PDCP entity504receives the PDUs for transmitting, the transmitting PDCP entity504is scheduled to transmit 1000 bytes (e.g., the ten packets at 100 bytes each). Additionally, the PDCP count associated with the primary RLC leg510and the secondary RLC leg512are each empty.

After receiving the PDUs for transmitting (e.g., at514), the transmitting PDCP entity504transmits scheduling information that is received by the receiving PDCP entity502. The scheduling information may facilitate transmitting the PDUs to the receiving PDCP entity502via a respective RLC leg. For example, the transmitting PDCP entity504may transmit primary scheduling information516that is received by the receiving PDCP entity502to transmit packets via the primary RLC leg510. The transmitting PDCP entity504may also transmit secondary scheduling information518that is received by the receiving PDCP entity502to transmit packets via the secondary RLC leg512. The transmitting PDCP entity504may transmit the primary scheduling information516and the secondary scheduling information518via the primary RLC leg510and/or the secondary RLC leg512.

As described above, the transmitting PDCP entity504may be part of a UE or may be part of a base station. In examples in which the transmitting PDCP entity504is part of a UE, the scheduling information may correspond to scheduling requests requesting an uplink grant from the receiving PDCP entity502. For example, the primary scheduling information516may include a scheduling request requesting an uplink scheduling grant to transmit packets to the receiving PDCP entity502via the primary RLC leg510, and the secondary scheduling information518may include a scheduling request requesting an uplink scheduling grant to transmit packets to the receiving PDCP entity502via the secondary RLC leg512. In some examples, the primary scheduling information516and the secondary scheduling information518may include the total data volume for transmitting. For example, the primary scheduling information516and the secondary scheduling information518may indicate a total data volume of 1000 bytes for transmitting.

After transmitting the scheduling requests, the transmitting PDCP entity504may receive uplink scheduling grants from the receiving PDCP entity502based in part on the scheduling requests. For example, the receiving PDCP entity502may transmit a primary leg grant520that is received at the transmitting PDCP entity504for transmitting packets via the primary RLC leg510. The receiving PDCP entity502may also transmit a secondary leg grant522that is received at the transmitting PDCP entity504for transmitting packets via the secondary RLC leg512. The primary leg grant520and the secondary leg grant522may allocate a volume of data to the transmitting PDCP entity504to transmit via the respective RLC leg. For example, the transmitting PDCP entity504may receive a grant via the primary leg grant520to transmit 500 bytes via the primary RLC leg510. The transmitting PDCP entity504may also receive a grant via the secondary leg grant522to transmit 300 bytes via the secondary RLC leg512.

In examples in which the transmitting PDCP entity504is part of a base station, the scheduling information may include downlink scheduling information. For example, the primary scheduling information516may include downlink scheduling information scheduling packets for transmitting to the transmitting PDCP entity504via the primary RLC leg510. The secondary scheduling information518may include downlink scheduling information scheduling packets for transmitting to the transmitting PDCP entity504via the secondary RLC leg512. In the illustrated example ofFIG.5, the primary scheduling information516may indicate a resource allocation of 500 bytes via the primary RLC leg510, and the secondary scheduling information518may indicate a resource allocation of 300 bytes via the secondary RLC leg512.

The transmitting PDCP entity504may then transmit packets that are received by the receiving PDCP entity502via a primary leg transmission524and a secondary leg transmission526. The transmitting PDCP entity504may transmit the primary leg transmission524to the receiving PDCP entity502via the primary RLC leg510. The transmitting PDCP entity504may transmit the secondary leg transmission526to the receiving PDCP entity502via the secondary RLC leg512. The packets transmitted via the primary leg transmission524and the secondary leg transmission526may be based in part on the primary scheduling information516and the secondary scheduling information518. For example, the transmitting PDCP entity504may transmit a subset of the PDUs based on the data volume indicated in a grant scheduling an uplink transmission or based on the resource allocation indicated in downlink scheduling information.

In the illustrated example ofFIG.5, time T1of the table590indicates a status of the transmitting PDCP entity504after processing the primary scheduling information516and the secondary scheduling information518. For example, the transmitting PDCP entity504may transmit 500 bytes (e.g., five packets) to the receiving PDCP entity502via the primary leg transmission524. Additionally, the transmitting PDCP entity504may transmit 300 bytes (e.g., three packets) to the receiving PDCP entity502via the secondary leg transmission526. In the table590, the PDCP count and the RLC sequence number (SN) for both RLC legs start with zero. Thus, as shown in the example ofFIG.5, the transmitting PDCP entity504transmits packets 0, 1, 2, 3, and 4 via the primary leg transmission524, as indicated by the entry of the primary leg transmission window column596corresponding to the time T1. The transmitting PDCP entity504transmits packets 5, 6, and 7 via the secondary leg transmission526, as indicated by the entry of the secondary leg transmission window column598corresponding to the time T1. Additionally, with the eight packets transmitted via the primary leg transmission524and the secondary leg transmission526, the PDCP data volume at time T1is 200 bytes (e.g., 1000 bytes−500 bytes−300 bytes=200 bytes).

As shown inFIG.5, the transmitting PDCP entity504transmits another transmission530that is received by the receiving PDCP entity502. The transmitting PDCP entity504may transmit the transmission530to transmit the remaining data of the PDUs (e.g., the remaining 200 bytes). The transmitting PDCP entity504may transmit the transmission530via the primary RLC leg510or the secondary RLC leg512. In the illustrated example ofFIG.5, the transmitting PDCP entity504transmits the transmission530via the primary RLC leg510.

As described above, the transmitting PDCP entity504may be part of a UE or a base station. In examples in which the transmitting PDCP entity504is part of a UE, the transmitting PDCP entity504may receive a grant528allocating resources for the transmitting PDCP entity504to use to transmit the transmission530. As shown inFIG.5, the grant528may allocate 500 bytes to the transmitting PDCP entity504to use to transmit the transmission530via the primary RLC leg510. In other examples in which the transmitting PDCP entity504is part of a base station, the transmitting PDCP entity504may transmit downlink scheduling information to the receiving PDCP entity502scheduling a resource allocation for the transmission530.

Although the example ofFIG.5illustrates the transmitting PDCP entity504transmitting the remaining data via the primary RLC leg510, in other examples, the transmitting PDCP entity504may transmit the remaining data via the secondary RLC leg512and/or a combination of the primary RLC leg510and the secondary RLC leg512.

Time T2of the table590indicates a status of the transmitting PDCP entity504after transmitting the remaining data (e.g., the remaining 200 bytes). For example, the transmitting PDCP entity504may transmit the two remaining packets of the ten packets associated with the PDUs via the transmission530. As indicated by the entry of the primary leg transmission window column596corresponding to the time T2, the transmitting PDCP entity504transmits the packets 8 and 9 via the primary RLC leg510. Additionally, the PDCP data volume at the time T2is 0 bytes (e.g., 200 bytes−200 bytes=0 bytes).

In the illustrated example ofFIG.5, the receiving PDCP entity502transmits a primary RLC status report532that is received by the transmitting PDCP entity504. The primary RLC status report532indicates a status of the packets transmitted by the transmitting PDCP entity504via the primary RLC leg510. For example, the primary RLC status report532may indicate that zero or more of the packets transmitted via the primary RLC leg510were received (e.g., via an ACK) or not received (e.g., via a NACK). In some examples, the primary RLC status report532may include a bitmap in which each bit of the bitmap corresponds to a packet and a value of the bit indicates whether the packet was received or not received. For example, the primary RLC status report532includes a bitmap533of seven bits corresponding to the packets 0, 1, 2, 3, 4, 8, and 9, respectively. Additionally, in the example ofFIG.5, each bit of the bitmap533is set to a value (e.g., a “1”) to indicate that transmission of the respective packet was successful at the receiving PDCP entity502.

In the example ofFIG.5, the receiving PDCP entity502also transmits a secondary RLC status report534that is received by the transmitting PDCP entity504. The secondary RLC status report534indicates a status of the packets transmitted by the transmitting PDCP entity504via the secondary RLC leg512. For example, the secondary RLC status report534includes a bitmap535of three bits corresponding to the packets 5, 6, and 7, respectively. Additionally, in the example ofFIG.5, each bit of the bitmap535is set to a value (e.g., a “0”) to indicate that transmission of the respective packet was unsuccessful (e.g., not received by the receiving PDCP entity502). In some examples, differences in successfulness of the packet transmissions between the primary RLC leg510and the secondary RLC leg512may be due to different respective channel conditions. For example, the primary RLC leg510and the secondary RLC leg512may be associated with different block error rates (BLER) that contribute to one or more of the packets being successfully received or unsuccessfully received at the receiving PDCP entity502via the respective RLC leg.

Although the example ofFIG.5illustrates the transmitting PDCP entity504receiving the primary RLC status report532and the secondary RLC status report534, in other examples, the transmitting PDCP entity504may receive one of the primary RLC status report532and the secondary RLC status report534, or may receive neither the primary RLC status report532nor the secondary RLC status report534. In such examples, the transmitting PDCP entity504may determine the successfulness of the transmissions based on the RLC status reports received or not received. Additionally, or alternatively, the primary RLC status report532and the secondary RLC status report534may be combined in a single RLC status report and/or the bitmap533and the bitmap535may be combined in a single bitmap.

In the example ofFIG.5, time T3of the table590indicates a status of the transmitting PDCP entity504after processing the primary RLC status report532and the secondary RLC status report534. For example, the PDCP data volume remains 0 bytes and the PDCP count associated with the primary RLC leg510is reset to empty as the packets transmission via the primary RLC leg510was indicated as successful by the primary RLC status report532. However, the PDCP count associated with the secondary RLC leg512is unchanged as the packets transmission via the secondary RLC leg512was indicated as unsuccessful via the secondary RLC status report534. Additionally, based on the PDCP count of the packets, the receiving PDCP entity502may be aware that it has received packets 0, 1, 2, 3, 4, 8, and 9, and not received packets 5, 6, and 7. For example, the receiving PDCP entity502may initiate a timer536(e.g., which may be referred to as a “t-reordering” timer or by any other name). The timer536may be used by the receiving PDCP entity502to detect loss of PDCP packets. For example, when the timer536expires, the receiving PDCP entity502may provide the received packets to an upper network layer that may determine that certain packets are missing based on the PDCP count associated with the received packets. For example, if the timer536expired at time T3, the receiving PDCP entity502may provide the packets 0, 1, 2, 3, 4, 8, and 9 to the upper network layer, which may determine that the packets 5, 6, and 7 are missing.

In the illustrated example ofFIG.5, at540, the transmitting PDCP entity504performs a PDCP recovery and any outstanding packets are considered data to be sent. For example, the transmitting PDCP entity504may convert all outstanding packets to retransmission data. At time T4, as shown in the example table590, the three outstanding packets (e.g., the packets 5, 6, and 7) are converted to retransmission data, and the PDCP data volume is updated to 300 bytes corresponding to the three outstanding packets. Additionally, the PDCP count associated with the primary RLC leg510and the secondary RLC leg512are reset and set to empty, as shown in the respective entries of the primary leg transmission window column596and the secondary leg transmission window column598.

After performing the PDCP recovery (e.g., at540), the transmitting PDCP entity504ofFIG.5has a PDPC data volume of 300 bytes, but the data split threshold volume508is set to 500 bytes. In scenarios in which the transmitting PDCP entity504relies on just the primary RLC leg510to transmit the high priority data (e.g., the packets 5, 6, and 7 in the example ofFIG.5), the timer536may expire before the high priority data is successfully received by the receiving PDCP entity502. For example, channel conditions associated with the primary RLC leg510may have degraded after the primary leg transmission524and subsequent transmissions via the primary RLC leg510may be unsuccessful. In additional or alternate examples, the resource allocation for the transmission546may be low and, thus, multiple transmissions may be needed to transmit the high priority data. For example, the transmitting PDCP entity504may be allocated (e.g., via a grant or downlink scheduling information) 100 bytes of resources for transmissions via the primary RLC leg510. In such scenarios, the transmitting PDCP entity504would need three transmissions to complete the transmission of packets 5, 6, and 7.

To reduce occurrences in which the timer536may expire because the transmitting PDCP entity504is attempting to transmit the three packets via the primary RLC leg510, aspects disclosed herein enable the transmitting PDCP entity504to transmit high priority data via the primary RLC leg510and/or the secondary RLC leg512regardless of the data volume of the high priority data. For example, detecting high priority data may trigger the transmitting PDCP entity504to transmit scheduling information for transmitting via the primary RLC leg510and/or the secondary RLC leg512. The transmitting PDCP entity504may transmit the scheduling information when the PDCP data is high priority data, but the PDCP data volume fails to satisfy (e.g., is less than) the data split threshold volume508. For example, the transmitting PDCP entity504may transmit primary scheduling information542to transmit data via the primary RLC leg510and may transmit secondary scheduling information544to transmit data via the secondary RLC leg512even though the PDCP data volume (e.g., 300 bytes) is less than the data split threshold volume508(e.g., 500 bytes).

As described above, the scheduling information may include transmitting a scheduling request and receiving a grant (e.g., when the transmitting PDCP entity504is part of a UE) or may include transmitting downlink scheduling information (e.g., when the transmitting PDCP entity504is part of a base station).

In the illustrated example ofFIG.5, the transmitting PDCP entity504transmits a transmission546that is received by the receiving PDCP entity502. The transmission546may include the three packets (e.g., the packets 5, 6, and 7) converted to retransmission data when the transmitting PDCP entity504performed the PDCP recovery (e.g., at540). In the illustrated example ofFIG.5, the transmitting PDCP entity504transmits the transmission546via the secondary RLC leg512. However, in other examples, the transmitting PDCP entity504may transmit the transmission546via the primary RLC leg510and/or the secondary RLC leg512.

Time T5of the table590indicates a status of the transmitting PDCP entity504after processing the primary scheduling information542and the secondary scheduling information544. For example, the transmitting PDCP entity504may transmit the three retransmission packets (e.g., the packets 5, 6, and 7) to the receiving PDCP entity502via the secondary RLC leg512. Thus, as shown in the example ofFIG.5, the transmitting PDCP entity504transmits packets 5, 6, and 7 via the transmission546, as indicated by the entry of the secondary leg transmission window column598corresponding to the time T5. Additionally, with the three packets transmitted via the transmission546, the PDCP data volume at time T0is 0 bytes (e.g., 300 bytes-300 bytes=0 bytes).

In the table590, the RLC sequence number for both RLC legs is reset to zero when the PDCP recovery is performed, but the PDCP count remains the same. Thus, the PDCP count packet “5” corresponds to the RLC sequence number “0,” the PDCP count packet “6” corresponds to the RLC sequence number “1,” and the PDCP count packet “7” corresponds to the RLC sequence number “2.”

In the illustrated example ofFIG.5, the PDUs received for transmitting (e.g., at514) include data for a new transmission (sometimes referred to as an “original” transmission). In some examples, the PDUs received for transmitting include control information, such as a status report, ROHC feedback, or EHC feedback. Control information may also be processed as high priority data by the transmitting PDCP entity504. For example, if the data for transmitting is control information and the data volume of the control information fails to satisfy the data split threshold volume508(e.g., the data volume is less than the 500 bytes in the example ofFIG.5), then the transmitting PDCP entity504may transmit the primary scheduling information516and the secondary scheduling information518to facilitate transmitting the control information via the primary RLC leg510and/or the secondary RLC leg512. Thus, the transmitting PDCP entity504may perform a best effort to transmit the control information to the receiving PDCP entity502while limiting delay of the transmission.

Although the example ofFIG.5illustrates a primary RLC leg510and a secondary RLC leg512, it may be appreciated that the secondary RLC leg512may include one or more RLC legs. For example, the receiving PDCP entity502and the transmitting PDCP entity504may include two or more secondary RLC entities. In such scenarios, the transmitting PDCP entity504may attempt to transmit high priority data, regardless of the volume of the high priority data, via the primary RLC leg and the one or more secondary RLC legs.

FIG.6is a flowchart600of a method of wireless communication. The method may be performed by a transmitting PDCP entity, such as the transmitting PDCP entity504ofFIG.5. In some examples, the transmitting PDPC entity may be part of a UE. In other examples, the transmitting PDPC entity may be part of a base station. The method may facilitate improving reliability of data transmissions by enabling the transmitting PDCP entity to attempt to transmit high priority data via the primary RLC leg and the one or more secondary RLC legs, regardless of the volume of the high priority data.

At602, the transmitting PDCP entity determines whether there is high priority data to transmit. For example, the transmitting PDCP entity may determine if there is retransmission data to transmit or if there is control information to transmit. In some examples, the transmitting PDCP entity may convert outstanding packets to retransmission data, as described in connection with540ofFIG.5. In some examples, the transmitting PDCP entity may receive PDUs including control information, such as a status report, ROHC feedback, and/or EHC feedback, as described in connection with514ofFIG.5.

If, at602, the transmitting PDCP entity determines that there is high priority data to transmit, then, at606, the transmitting PDCP entity transmits scheduling information on both RLC legs, as described in connection with the primary scheduling information516and the secondary scheduling information518, and/or the primary scheduling information542and the secondary scheduling information544ofFIG.5. The scheduling information may include transmitting a scheduling request (e.g., when the transmitting PDCP entity is part of a UE) or may include transmitting downlink scheduling information (e.g., when the transmitting PDCP entity is part of a base station).

After transmitting the scheduling information on both RLC legs (e.g., at606), the transmitting PDCP entity may transmit, at610, the data based on the scheduling information. For example, the transmitting PDCP entity may transmit the data based on an allocation of resources received in an uplink scheduling grant or an allocation of resources indicated by downlink scheduling information, as described in connection with the primary leg transmission524, the secondary leg transmission526, the transmission530, and/or the transmission546ofFIG.5.

If, at602, the transmitting PDCP entity determines that there is not high priority data to transmit, then, at604, the transmitting PDCP entity determines whether the total PDCP data volume satisfies a data split threshold volume. For example, the transmitting PDCP entity may determine whether the total PDCP data volume is greater than or equal to the data split threshold volume.

If, at604, the transmitting PDCP entity determines that the total PDCP data volume satisfies the data split threshold volume, then control proceeds to606and the transmitting PDCP entity transmits scheduling information on both RLC legs, as described in connection with the primary scheduling information516and the secondary scheduling information518, and/or the primary scheduling information542and the secondary scheduling information544ofFIG.5. The scheduling information may include transmitting a scheduling request (e.g., when the transmitting PDCP entity is part of a UE) or may include transmitting downlink scheduling information (e.g., when the transmitting PDCP entity is part of a base station).

If, at604, the transmitting PDCP entity determines that the total PDCP data volume does not satisfy the data split threshold volume (e.g., the total PDCP data volume is less than the data split threshold volume), then, at608, the transmitting PDCP entity transmits scheduling information on the primary RLC leg, as described in connection with the primary scheduling information516and/or the primary scheduling information542.

After transmitting the scheduling information on the primary RLC leg (e.g., at608), the transmitting PDCP entity may transmit, at610, the data based on the scheduling information. For example, the transmitting PDCP entity may transmit the data based on an allocation of resources received in an uplink scheduling grant or an allocation of resources indicated by downlink scheduling information, as described in connection with the primary leg transmission524and/or the transmission530ofFIG.5.

FIG.7is a flowchart700of a method of wireless communication. The method may be performed by a first network node, such as the transmitting PDCP entity504ofFIG.5. In some examples, the first network node may be part of a UE (e.g., the UE104, the UE350, and/or an apparatus802ofFIG.8). In other examples, the first network node may be part of a base station (e.g., the base station102/180, the base station310, and/or an apparatus902ofFIG.9). The method may facilitate improving reliability of data transmissions by enabling the first network node to attempt to transmit high priority data via the primary RLC leg and the one or more secondary RLC legs, regardless of the volume of the high priority data.

At702, the first network node receives PDUs for transmitting to a second network node while operating in a dual connectivity mode associated with a first RLC leg and at least a second RLC leg, as described in connection with514ofFIG.5. The PDUs may be associated with at least one of control information or retransmission data. The receiving of the PDUs for transmitting, at702, may be performed by a packets component840of the apparatus802ofFIG.8and/or a packets component940of the apparatus902ofFIG.9.

At704, the first network node transmits first scheduling information via the first RLC leg and transmits second scheduling information via the second RLC leg based on the PDUs being associated with at least one of the control information or the retransmission data, as described in connection with the primary scheduling information516, the secondary scheduling information518, the primary scheduling information542, and/or the secondary scheduling information544of FIG. The transmitting of the first scheduling information and the second scheduling information, at704, may be performed by a scheduling information component842of the apparatus802ofFIG.8and/or a scheduling information component942of the apparatus902ofFIG.9.

In some examples, the first network node may transmit the first scheduling information via the first RLC leg and transmitting the second scheduling information via the second RLC leg in response to the PDUs including the control information. For example, the control information may include a status report, ROHC feedback, or EHC feedback.

In some examples, the first network node may transmit the first scheduling information via the first RLC leg and transmitting the second scheduling information via the second RLC leg in response to the PDUs including the retransmission data, as described in connection with the PDCP data at time T4ofFIG.5.

In some examples, the first network node may be part of a user equipment, and the second network node may be part of a base station. In such examples, the first scheduling information may include a first scheduling request and the second scheduling information may include a second scheduling request. The first network node may receive a grant scheduling a transmission via at least one of the first RLC leg and the second RLC leg, as described in connection with the primary leg grant520, the secondary leg grant522, the grant528, and/or the secondary scheduling information544ofFIG.5. The first network node may then transmit the PDUs on at least one of the first RLC leg and the second RLC leg based on the grant, as described in connection with the primary leg transmission524, the secondary leg transmission526, the transmission530, and/or the transmission546.

In some examples, the first network node (e.g., a UE) may transmit the first scheduling request via the first RLC leg when a data volume of the PDUs fails to satisfy a threshold volume (e.g., the data split threshold volume508), as described in connection with the primary scheduling information542and the PDCP data volume at time T4ofFIG.5and/or at606ofFIG.6. The example first network node (e.g., a UE) may also transmit the second scheduling request via the second RLC leg when the data volume of the PDUs fails to satisfy the threshold volume, as described in connection with the secondary scheduling information544and the PDCP data volume at time T4ofFIG.5and/or at606ofFIG.6

In some examples, the first network node may be part of a base station, and the second network node may be part of a UE. In such examples, the first scheduling information may include first downlink scheduling information, and the second scheduling information may include second downlink scheduling information.

In some examples, the first network node (e.g., a base station) may transmit the first scheduling request via the first RLC leg when a data volume of the PDUs fails to satisfy a threshold volume, as described in connection with the primary scheduling information542and the PDCP data volume at time T4ofFIG.5and/or at606ofFIG.6. The example first network node (e.g., a base station) may also transmit the second scheduling request via the second RLC leg when the data volume of the PDUs fails to satisfy the threshold volume, as described in connection with the secondary scheduling information544and the PDCP data volume at time T4ofFIG.5and/or at606ofFIG.6

FIG.8is a diagram800illustrating an example of a hardware implementation for an apparatus802. The apparatus802may be a UE, a component of a UE, or may implement UE functionality. In some aspects, the apparatus802may include a cellular baseband processor804(also referred to as a modem) coupled to a cellular RF transceiver822. In some aspects, the apparatus802may further include one or more subscriber identity modules (SIM) cards820, an application processor806coupled to a secure digital (SD) card808and a screen810, a Bluetooth module812, a wireless local area network (WLAN) module814, a Global Positioning System (GPS) module816, or a power supply818. The cellular baseband processor804communicates through the cellular RF transceiver822with the UE104and/or base station102/180. The cellular baseband processor804may include a computer-readable medium/memory. The computer-readable medium/memory may be non-transitory. The cellular baseband processor804is responsible for general processing, including the execution of software stored on the computer-readable medium/memory. The software, when executed by the cellular baseband processor804, causes the cellular baseband processor804to perform the various functions described supra. The computer-readable medium/memory may also be used for storing data that is manipulated by the cellular baseband processor804when executing software. The cellular baseband processor804further includes a reception component830, a communication manager832, and a transmission component834. The communication manager832includes the one or more illustrated components. The components within the communication manager832may be stored in the computer-readable medium/memory and/or configured as hardware within the cellular baseband processor804. The cellular baseband processor804may be a component of the UE350and may include the memory360and/or at least one of the TX processor368, the RX processor356, and the controller/processor359. In one configuration, the apparatus802may be a modem chip and include just the cellular baseband processor804, and in another configuration, the apparatus802may be the entire UE (e.g., see the UE350ofFIG.3) and include the additional modules of the apparatus802.

The communication manager832includes a packets component840that is configured to receive PDUs for transmitting to a second network node while operating in a dual connectivity mode associated with a first RLC leg and at least a second RLC leg, the PDUs associated with at least one of control information or retransmission data, for example, as described in connection with702ofFIG.7.

The communication manager832also includes a scheduling information component842that is configured to transmit first scheduling information via the first RLC leg and transmitting second scheduling information via the second RLC leg based on the PDUs being associated with at least one of the control information or the retransmission data, for example, as described in connection with606ofFIGS.6and/or704ofFIG.7. The example scheduling information component842may also be configured to transmit the first scheduling information via the first RLC leg and transmitting the second scheduling information via the second RLC leg in response to the PDUs including the control information. The example scheduling information component842may also be configured to transmit the first scheduling information via the first RLC leg and transmitting the second scheduling information via the second RLC leg in response to the PDUs including the retransmission data. The example scheduling information component842may also be configured to transmit the first scheduling request via the first RLC leg when a data volume of the PDUs fails to satisfy a threshold volume. The example scheduling information component842may also be configured to transmit the second scheduling request via the second RLC leg when the data volume of the PDUs fails to satisfy the threshold volume.

The example reception component830may also be configured to receive a grant scheduling a transmission via at least one of the first RLC leg and the second RLC leg.

The example transmission component834may also be configured to transmit the PDUs on at least one of the first RLC leg and the second RLC leg based on the grant.

As shown, the apparatus802may include a variety of components configured for various functions. In one configuration, the apparatus802, and in particular the cellular baseband processor804, includes means for receiving PDUs for transmitting to a second network node while operating in a dual connectivity mode associated with a first RLC leg and at least a second RLC leg, the PDUs associated with at least one of control information or retransmission data. The example apparatus802also includes means for transmitting first scheduling information via the first RLC leg and transmitting second scheduling information via the second RLC leg based on the PDUs being associated with at least one of the control information or the retransmission data.

In another configuration, the example apparatus802also includes means for transmitting the first scheduling information via the first RLC leg and transmitting the second scheduling information via the second RLC leg in response to the PDUs including the control information.

In another configuration, the example apparatus802also includes means for transmitting the first scheduling information via the first RLC leg and transmitting the second scheduling information via the second RLC leg in response to the PDUs including the retransmission data.

In another configuration, the example apparatus802also includes means for receiving a grant scheduling a transmission via at least one of the first RLC leg and the second RLC leg. The example apparatus802also includes means for transmitting the PDUs on at least one of the first RLC leg and the second RLC leg based on the grant.

The means may be one or more of the components of the apparatus802configured to perform the functions recited by the means. As described supra, the apparatus802may include the TX processor368, the RX processor356, and the controller/processor359. As such, in one configuration, the means may be the TX processor368, the RX processor356, and the controller/processor359configured to perform the functions recited by the means.

FIG.9is a diagram900illustrating an example of a hardware implementation for an apparatus902. The apparatus902may be a base station, a component of a base station, or may implement base station functionality. In some aspects, the apparatus902may include a baseband unit904. The baseband unit904may communicate through a cellular RF transceiver922with the UE104. The baseband unit904may include a computer-readable medium/memory. The baseband unit904is responsible for general processing, including the execution of software stored on the computer-readable medium/memory. The software, when executed by the baseband unit904, causes the baseband unit904to perform the various functions described supra. The computer-readable medium/memory may also be used for storing data that is manipulated by the baseband unit904when executing software. The baseband unit904further includes a reception component930, a communication manager932, and a transmission component934. The communication manager932includes the one or more illustrated components. The components within the communication manager932may be stored in the computer-readable medium/memory and/or configured as hardware within the baseband unit904. The baseband unit904may be a component of the base station310and may include the memory376and/or at least one of the TX processor316, the RX processor370, and the controller/processor375.

The communication manager932includes a packets component940that is configured to receive PDUs for transmitting to a second network node while operating in a dual connectivity mode associated with a first RLC leg and at least a second RLC leg, the PDUs associated with at least one of control information or retransmission data, for example, as described in connection with702ofFIG.7.

The communication manager932also includes a scheduling information component942that is configured to transmit first scheduling information via the first RLC leg and transmitting second scheduling information via the second RLC leg based on the PDUs being associated with at least one of the control information or the retransmission data, for example, as described in connection with606ofFIGS.6and/or704ofFIG.7. The example scheduling information component942may also be configured to transmit the first scheduling information via the first RLC leg and transmitting the second scheduling information via the second RLC leg in response to the PDUs including the control information. The example scheduling information component942may also be configured to transmit the first scheduling information via the first RLC leg and transmitting the second scheduling information via the second RLC leg in response to the PDUs including the retransmission data. The example scheduling information component942may also be configured to transmit the first scheduling request via the first RLC leg when a data volume of the PDUs fails to satisfy a threshold volume. The example scheduling information component942may also be configured to transmit the second scheduling request via the second RLC leg when the data volume of the PDUs fails to satisfy the threshold volume.

As shown, the apparatus902may include a variety of components configured for various functions. In one configuration, the apparatus902, and in particular the baseband unit904, includes means for receiving PDUs for transmitting to a second network node while operating in a dual connectivity mode associated with a first RLC leg and at least a second RLC leg, the PDUs associated with at least one of control information or retransmission data. The example apparatus902also includes means for transmitting first scheduling information via the first RLC leg and transmitting second scheduling information via the second RLC leg based on the PDUs being associated with at least one of the control information or the retransmission data.

In another configuration, the example apparatus902also includes means for transmitting the first scheduling information via the first RLC leg and transmitting the second scheduling information via the second RLC leg in response to the PDUs including the control information.

In another configuration, the example apparatus902also includes means for transmitting the first scheduling information via the first RLC leg and transmitting the second scheduling information via the second RLC leg in response to the PDUs including the retransmission data.

In another configuration, the example apparatus902also includes means for transmitting the first downlink scheduling information via the first RLC leg when a data volume of the PDUs fails to satisfy a threshold volume. The example apparatus902also includes means for transmitting the second downlink scheduling information via the second RLC leg when the data volume of the PDUs fails to satisfy the threshold volume.

The means may be one or more of the components of the apparatus902configured to perform the functions recited by the means. As described supra, the apparatus902may include the TX processor316, the RX processor370, and the controller/processor375. As such, in one configuration, the means may be the TX processor316, the RX processor370, and the controller/processor375configured to perform the functions recited by the means.

Aspect 1 is a method of wireless communication at a first network node, comprising: receiving PDUs for transmitting to a second network node while operating in a dual connectivity mode associated with a first RLC leg and at least a second RLC leg, the PDUs associated with at least one of control information or retransmission data; and transmitting first scheduling information via the first RLC leg and transmitting second scheduling information via the second RLC leg based on the PDUs being associated with at least one of the control information or the retransmission data.

Aspect 2 is the method of aspect 1, further including: transmitting the first scheduling information via the first RLC leg and transmitting the second scheduling information via the second RLC leg in response to the PDUs including the control information.

Aspect 3 is the method of any of aspects 1 and 2, further including: transmitting the first scheduling information via the first RLC leg and transmitting the second scheduling information via the second RLC leg in response to the PDUs including the retransmission data.

Aspect 4 is the method of any of aspects 1 to 3, further including that the first network node includes a user equipment, the second network node includes a base station, the first scheduling information includes a first scheduling request, and the second scheduling information includes a second scheduling request.

Aspect 5 is the method of any of aspects 1 to 4, further including: receiving a grant scheduling a transmission via at least one of the first RLC leg and the second RLC leg; and transmitting the PDUs on at least one of the first RLC leg and the second RLC leg based on the grant.

Aspect 6 is the method of any of aspects 1 to 5, further including that the first network node transmits the second scheduling request via the second RLC leg independent of a threshold volume.

Aspect 7 is the method of any of aspects 1 to 3, further including that the first network node includes a base station, the second network node includes a user equipment, the first scheduling information includes first downlink scheduling information, and the second scheduling information includes second downlink scheduling information.

Aspect 8 is the method of any of aspects 1 and 7, further including that the first network node transmits the second downlink scheduling information via the second RLC leg independent of a threshold volume.

Aspect 9 is the method of any of aspects 1 to 8, further including that the control information includes a status report, a ROHC feedback, or an EHC feedback.

Aspect 10 is an apparatus for wireless communication comprising at least one processor coupled to a memory and configured to implement any of aspects 1 to 9.

Aspect 11 is an apparatus for wireless communication including means for implementing any of aspects 1 to 9.

Aspect 12 is a non-transitory computer-readable storage medium storing computer executable code, where the code, when executed, causes a processor to implement any of aspects 1 to 9.