WO2019218104A1

WO2019218104A1 - Packet delivery for multi-sim user equipment

Info

Publication number: WO2019218104A1
Application number: PCT/CN2018/086624
Authority: WO
Inventors: Ling Xie; Jiming Guo; Ruiming Zheng; Reza Shahidi; Mutaz Zuhier Afif SHUKAIR; Jun Hu
Original assignee: Qualcomm Inc
Current assignee: Qualcomm Inc
Priority date: 2018-05-12
Filing date: 2018-05-12
Publication date: 2019-11-21
Anticipated expiration: 2020-11-12

Abstract

The techniques described herein provide a procedure at a user equipment (UE) for managing a reordering timer used in a data transfer procedure at the UE. The reordering timer is conventionally used to provide time for a UE to wait to receive a missing data unit before delivering a set of data units to upper layers. If, however, the UE is receiving data from a base station according to a first subscription on a radio frequency (RF) chain, and is interrupted by communications with the base station according to a second subscription on the RF chain, the reordering timer may expire before the base station has a chance to retransmit missing data to the UE, for example. As described herein, the UE may support techniques for pausing (or freezing) the reordering timer when communications according to a first subscription is interrupted by communications according to a second subscription.

Description

PACKET DELIVERY FOR MULTI-SIM USER EQUIPMENT

BACKGROUND

The following relates generally to wireless communications and more specifically to packet delivery for multi-subscriber identity module (multi-SIM) user equipments (UEs) .

Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power) . Examples of such multiple-access systems include fourth generation (4G) systems such as Long Term Evolution (LTE) systems, LTE-Advanced (LTE-A) systems, or LTE-A Pro systems, and fifth generation (5G) systems which may be referred to as New Radio (NR) systems. These systems may employ technologies such as code division multiple access (CDMA) , time division multiple access (TDMA) , frequency division multiple access (FDMA) , orthogonal frequency division multiple access (OFDMA) , or discrete Fourier transform-spread-OFDM (DFT-S-OFDM) .

A wireless multiple-access communications system may include a number of base stations or network access nodes, each simultaneously supporting communication for multiple communication devices, which may be otherwise known as UEs. Some UEs may support communication with a network using multiple subscriptions associated with multiple subscriber identity modules (SIMs) at the UEs. Such UEs may be referred to as multi-SIM UEs. In some cases, a multi-SIM UE may use the same radio to communicate with networks according to different subscriptions. Conventional techniques at a UE for communicating with networks via the same radio according to different subscriptions are deficient.

SUMMARY

The described techniques relate to improved methods, systems, devices, or apparatuses for managing packet reordering for a data transfer procedure at a multi-subscriber identity module (SIM) (multi-SIM) user equipment (UE) . Packet reordering may occur at a radio interface protocol layer (e.g., packet data convergence protocol (PDCP) layer) of the UE and may employ a reordering timing. The reordering timer is conventionally used to provide time for a UE to wait to receive a missing data unit before delivering a set of data units to upper layers. If, however, a multi-SIM UE is receiving data from a base station according to a first subscription on a radio (e.g., a radio with one or more radio frequency (RF) chains for communication with networks) , and the multi-SIM UE is interrupted by communications with the base station according to a second subscription on the radio, the reordering timer may expire before the base station has a chance to retransmit missing data units to the UE or before lower layers of the multi-SIM UE have a chance to recover the missing data unit (e.g., via one or more retransmissions) . As described herein, a multi-SIM UE may support techniques for adapting the reordering timer when communications according to a first subscription are interrupted by communications according to a second subscription. For instance, the reordering timer may be adapted by the radio interface protocol layer at the UE based on indications from a physical layer related to service interruptions for communications using the first subscription by communications using a second subscription. Additionally, techniques for employing and adapting a delivery timer for forcing delivery of out-of-order data units based on the indications and data unit flow are described.

A method for wireless communication at a radio interface protocol layer of a UE is described. The method may include receiving a subset of a series of data units from a first base station via an RF chain according to a first subscription associated with a first SIM of the UE, starting a reordering timer for the series of data units upon identifying at least one missing data unit in the received subset of the series of data units, receiving, from a physical layer, an indication that the RF chain is being used for communicating with a second base station according to a second subscription associated with a second SIM of the UE, pausing the reordering timer based on receiving the indication, and delivering the subset of the series of data units to a higher layer based on the reordering timer.

An apparatus for wireless communication at a radio interface protocol layer of a UE is described. The apparatus may include a processor, memory in electronic communication with the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to receive a subset of a series of data units from a first base station via an RF chain according to a first subscription associated with a first SIM of the UE, start a reordering timer for the series of data units upon identifying at least one missing data unit in the received subset of the series of data units, receive, from a physical layer, an indication that the RF chain is being used for communicating with a second base station according to a second subscription associated with a second SIM of the UE, pause the reordering timer based on receiving the indication, and deliver the subset of the series of data units to a higher layer based on the reordering timer.

Another apparatus for wireless communication at a radio interface protocol layer of a UE is described. The apparatus may include means for receiving a subset of a series of data units from a first base station via an RF chain according to a first subscription associated with a first SIM of the UE, starting a reordering timer for the series of data units upon identifying at least one missing data unit in the received subset of the series of data units, receiving, from a physical layer, an indication that the RF chain is being used for communicating with a second base station according to a second subscription associated with a second SIM of the UE, pausing the reordering timer based on receiving the indication, and delivering the subset of the series of data units to a higher layer based on the reordering timer.

A non-transitory computer-readable medium storing code for wireless communication at a radio interface protocol layer of a UE is described. The code may include instructions executable by a processor to receive a subset of a series of data units from a first base station via an RF chain according to a first subscription associated with a first SIM of the UE, start a reordering timer for the series of data units upon identifying at least one missing data unit in the received subset of the series of data units, receive, from a physical layer, an indication that the RF chain is being used for communicating with a second base station according to a second subscription associated with a second SIM of the UE, pause the reordering timer based on receiving the indication, and deliver the subset of the series of data units to a higher layer based on the reordering timer.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for starting a delivery timer upon receiving the indication when the at least one missing data unit may be identified prior to receiving the indication or upon identifying the at least one missing data unit in the received subset of the series of data units when the at least one missing data unit may be identified after receiving the indication. Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for storing the subset of the series of data units received from the first base station and delivering the stored subset of the series of data units in ascending order to the higher layer after the delivery timer expires.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for triggering a data unit status report after the delivery timer expires. Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for storing the subset of the series of data units received from the first base station, receiving the at least one missing data unit before the delivery timer expires, delivering the stored subset of the series of data units in ascending order to the higher layer including the at least one missing data unit and resetting the delivery timer and the reordering timer.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the reordering timer may be started prior to receiving the indication, and where the reordering timer may be paused upon receiving the indication. In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the indication may be received prior to identifying the at least one missing data unit, and where the reordering timer may be started and paused upon identifying the at least one missing data unit.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for receiving, from the physical layer, a second indication that the RF chain may be switching from being used for communicating with the second base station according to the second subscription to being used for communicating with the first base station according to the first subscription. Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for extending the reordering timer upon receiving the second indication and resuming the reordering timer. Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for reverting the reordering timer to a configured value after the reordering timer expires.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for starting a wait timer upon receiving the second indication. Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for triggering a data unit status report after the wait timer expires when the radio interface protocol layer fails to receive the at least one missing data unit. Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for determining that a data unit status report was triggered after the expiration of a delivery timer and stopping the wait timer based on the determination.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of a wireless communications system that supports packet delivery for multi-subscriber identity module (multi-SIM) user equipment (UEs) in accordance with aspects of the present disclosure.

FIG. 2 illustrates an example of a series of data units received from a base station in accordance with aspects of the present disclosure.

FIG. 3 illustrates an example of a wireless communications system that supports packet delivery for multi-SIM UEs in accordance with aspects of the present disclosure.

FIGs. 4 and 5 illustrate example timelines of communications between base stations and a multi-SIM UE in accordance with aspects of the present disclosure.

FIG. 6 illustrates an example of a flow diagram that supports packet delivery for multi-SIM UEs in accordance with aspects of the present disclosure.

FIGs. 7 and 8 show block diagrams of devices that support packet delivery for multi-SIM UEs in accordance with aspects of the present disclosure.

FIG. 9 shows a block diagram of a communications manager that supports packet delivery for multi-SIM UEs in accordance with aspects of the present disclosure.

FIG. 10 shows a diagram of a system including a device that supports packet delivery for multi-SIM UEs in accordance with aspects of the present disclosure.

FIGs. 11 and 12 show flowcharts illustrating methods that support packet delivery for multi-SIM UEs in accordance with aspects of the present disclosure.

DETAILED DESCRIPTION

Some user equipment (UEs) may support communications with a network using multiple subscriptions associated with multiple subscriber identity modules (SIMs) at the UEs. Such UEs may be referred to as multi-subscriber identity module (multi-SIM) UEs. In some wireless communications systems, multi-SIM UEs and other UEs may use the same techniques for handling data units received from a base station. In particular, a radio interface protocol layer (e.g., packet data convergence protocol (PDCP) layer) at such UEs may receive data units from lower layers after the data units are received from a base station using a radio of the UE. When the radio interface protocol layer identifies a missing data unit (e.g., based on receiving an out-of-sequence data unit) , the radio interface protocol layer may start a reordering timer, and the radio interface protocol layer may wait to receive a missing data unit for the duration of the reordering timer before delivering a set of data units to an upper (or higher) layer. Thus, using the reordering timer, if a missing data unit is delayed, the radio interface protocol layer may avoid unnecessarily delivering data units to an upper layer out-of-order, since the radio interface protocol layer may receive the missing data unit before the reordering timer expires.

In some cases, however, at a multi-SIM UE, communications according to a first subscription may be interrupted by communications according to a second subscription. For instance, while receiving data units from a base station according to a first subscription at a UE via a radio, the UE may switch to communicating according to a second subscription at the UE via the radio. In such cases, if a reordering timer is running at a radio interface protocol layer at the UE for communications according to the first subscription, the reordering timer may run out while the radio is being used for communications according to the second subscription without giving the UE a chance to receive missing data units for communications according to the first subscription. As a result, the chances that data units are delivered out-of-order to an upper layer at the UE may increase, and a substantial amount of resources may be wasted for unnecessary retransmissions of data units and HARQ feedback.

As described herein, multi-SIM UEs may support efficient techniques for managing a reordering timer for packet delivery. In particular, a multi-SIM UE may be configured to pause a reordering timer that was started for communications according to a first subscription via a radio, when the radio is being used for communications according to a second subscription. For example, if a radio interface protocol layer identifies a missing data unit and starts a reordering timer associated with communications according to a first subscription via a radio, and the radio interface protocol layer receives an indication (i.e., while the reordering timer is running) that the RF chain is being used for communicating according to a second subscription, the radio interface protocol layer may pause the reordering timer. Similarly, if the radio interface protocol layer receives an indication that an RF chain is being used for communications according to a second subscription, and the radio interface protocol layer identifies a missing data unit associated with communications according to a first subscription, the radio interface protocol layer may start and pause the reordering timer associated with communications according to the first subscription.

Aspects of the disclosure introduced above are described below in the context of a wireless communications system. Examples of processes and signaling exchanges that support packet delivery for multi-SIM UEs are then described. Aspects of the disclosure are further illustrated by and described with reference to apparatus diagrams, system diagrams, and flowcharts that relate to packet delivery for multi-SIM UEs.

FIG. 1 illustrates an example of a wireless communications system 100 that supports packet delivery for multi-SIM UEs in accordance with aspects of the present disclosure. The wireless communications system 100 includes base stations 105, UEs 115, and a core network 130. In some examples, the wireless communications system 100 may be a Long Term Evolution (LTE) network, an LTE-Advanced (LTE-A) network, an LTE-A Pro network, or a New Radio (NR) network. In some cases, wireless communications system 100 may support enhanced broadband communications, ultra-reliable (e.g., mission critical) communications, low latency communications, or communications with low-cost and low-complexity devices.

Base stations 105 may wirelessly communicate with UEs 115 via one or more base station antennas. Base stations 105 described herein may include or may be referred to by those skilled in the art as a base transceiver station, a radio base station, an access point, a radio transceiver, a NodeB, an eNodeB (eNB) , a next-generation Node B or giga-nodeB (either of which may be referred to as a gNB) , a Home NodeB, a Home eNodeB, or some other suitable terminology. Wireless communications system 100 may include base stations 105 of different types (e.g., macro or small cell base stations) . The UEs 115 described herein may be able to communicate with various types of base stations 105 and network equipment including macro eNBs, small cell eNBs, gNBs, relay base stations, and the like.

Each base station 105 may be associated with a particular geographic coverage area 110 in which communications with various UEs 115 is supported. Each base station 105 may provide communication coverage for a respective geographic coverage area 110 via communication links 125, and communication links 125 between a base station 105 and a UE 115 may utilize one or more carriers. Communication links 125 shown in wireless communications system 100 may include uplink transmissions from a UE 115 to a base station 105, or downlink transmissions from a base station 105 to a UE 115. Downlink transmissions may also be called forward link transmissions while uplink transmissions may also be called reverse link transmissions.

The geographic coverage area 110 for a base station 105 may be divided into sectors making up only a portion of the geographic coverage area 110, and each sector may be associated with a cell. For example, each base station 105 may provide communication coverage for a macro cell, a small cell, a hot spot, or other types of cells, or various combinations thereof. In some examples, a base station 105 may be movable and therefore provide communication coverage for a moving geographic coverage area 110. In some examples, different geographic coverage areas 110 associated with different technologies may overlap, and overlapping geographic coverage areas 110 associated with different technologies may be supported by the same base station 105 or by different base stations 105. The wireless communications system 100 may include, for example, a heterogeneous LTE/LTE-A/LTE-A Pro or NR network in which different types of base stations 105 provide coverage for various geographic coverage areas 110.

The term “cell” refers to a logical communication entity used for communication with a base station 105 (e.g., over a carrier) , and may be associated with an identifier for distinguishing neighboring cells (e.g., a physical cell identifier (PCID) , a virtual cell identifier (VCID) ) operating via the same or a different carrier. In some examples, a carrier may support multiple cells, and different cells may be configured according to different protocol types (e.g., machine-type communication (MTC) , narrowband Internet-of-Things (NB-IoT) , enhanced mobile broadband (eMBB) , or others) that may provide access for different types of devices. In some cases, the term “cell” may refer to a portion of a geographic coverage area 110 (e.g., a sector) over which the logical entity operates.

The term “carrier” refers to a set of radio frequency spectrum resources having a defined physical layer structure for supporting communications over a communication link 125. For example, a carrier of a communication link 125 may include a portion of a radio frequency spectrum band that is operated according to physical layer channels for a given radio access technology. Each physical layer channel may carry user data, control information, or other signaling. A carrier may be associated with a pre-defined frequency channel (e.g., an E-UTRA absolute radio frequency channel number (EARFCN) ) , and may be positioned according to a channel raster for discovery by UEs 115. Carriers may be downlink or uplink (e.g., in an FDD mode) , or be configured to carry downlink and uplink communications (e.g., in a TDD mode) . In some examples, signal waveforms transmitted over a carrier may be made up of multiple sub-carriers (e.g., using multi-carrier modulation (MCM) techniques such as OFDM or DFT-s-OFDM) .

UEs 115 may be dispersed throughout the wireless communications system 100, and each UE 115 may be stationary or mobile. A UE 115 may also be referred to as a mobile device, a wireless device, a remote device, a handheld device, or a subscriber device, or some other suitable terminology, where the “device” may also be referred to as a unit, a station, a terminal, or a client. A UE 115 may also be a personal electronic device such as a cellular phone, a personal digital assistant (PDA) , a tablet computer, a laptop computer, or a personal computer. In some examples, a UE 115 may also refer to a wireless local loop (WLL) station, an Internet of Things (IoT) device, an Internet of Everything (IoE) device, or an MTC device, or the like, which may be implemented in various articles such as appliances, vehicles, meters, or the like.

Base stations 105 may communicate with the core network 130 and with one another. For example, base stations 105 may interface with the core network 130 through backhaul links 132 (e.g., via an S1 or other interface) . Base stations 105 may communicate with one another over backhaul links 134 (e.g., via an X2 or other interface) either directly (e.g., directly between base stations 105) or indirectly (e.g., via core network 130) .

The core network 130 may provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. The core network 130 may be an evolved packet core (EPC) , which may include at least one mobility management entity (MME) , at least one serving gateway (S-GW) , and at least one Packet Data Network (PDN) gateway (P-GW) . The MME may manage non-access stratum (e.g., control plane) functions such as mobility, authentication, and bearer management for UEs 115 served by base stations 105 associated with the EPC. User IP packets may be transferred through the S-GW, which itself may be connected to the P-GW. The P-GW may provide IP address allocation as well as other functions. The P-GW may be connected to the network operators IP services. The operators IP services may include access to the Internet, Intranet (s) , an IP Multimedia Subsystem (IMS) , or a Packet-Switched (PS) Streaming Service.

At least some of the network devices, such as a base station 105, may include subcomponents such as an access network entity, which may be an example of an access node controller (ANC) . Each access network entity may communicate with UEs 115 through a number of other access network transmission entities, which may be referred to as a radio head, a smart radio head, or a transmission/reception point (TRP) . In some configurations, various functions of each access network entity or base station 105 may be distributed across various network devices (e.g., radio heads and access network controllers) or consolidated into a single network device (e.g., a base station 105) .

In some cases, UEs 115 and base stations 105 may support retransmissions of data to increase the likelihood that data is received successfully. Hybrid automatic repeat request (HARQ) feedback is one technique of increasing the likelihood that data is received correctly over a communication link 125. HARQ may include a combination of error detection (e.g., using a cyclic redundancy check (CRC) ) , forward error correction (FEC) , and retransmission (e.g., automatic repeat request (ARQ) ) . HARQ may improve throughput at the MAC layer in poor radio conditions (e.g., signal-to-noise conditions) . In some cases, a wireless device may support same-slot HARQ feedback, where the device may provide HARQ feedback in a specific slot for data received in a previous symbol in the slot. In other cases, the device may provide HARQ feedback in a subsequent slot, or according to some other time interval.

Wireless communications system 100 may be a packet-based network that operates according to a layered protocol stack. In the user plane, communications at the bearer or Packet Data Convergence Protocol (PDCP) layer may be IP-based. A Radio Link Control (RLC) layer may in some cases perform packet segmentation and reassembly to communicate over logical channels. A Medium Access Control (MAC) layer may perform priority handling and multiplexing of logical channels into transport channels. The MAC layer may also use HARQ to provide retransmission at the MAC layer to improve link efficiency. In the control plane, the Radio Resource Control (RRC) protocol layer may provide establishment, configuration, and maintenance of an RRC connection between a UE 115 and a base station 105 or core network 130 supporting radio bearers for user plane data. At the Physical (PHY) layer, transport channels may be mapped to physical channels.

In wireless communications system 100, a radio interface protocol layer (e.g., PDCP layer) at a UE 115 may perform reordering of data units (e.g., PDCP protocol data units (PDUs) ) received from a base station 105 before delivering the data units (e.g., PDCP service data units (SDUs) ) to upper layers, such as an Internet Protocol (IP) layer, user datagram protocol (UDP) layer, or a transmission control protocol (TCP) layer. FIG. 2 illustrates an example of a series of data units 200 received from a base station 105 in accordance with aspects of the present disclosure. In the example of FIG. 2, the radio interface protocol layer may receive a number of data units 210 in sequence up to data unit N-1, and the UE 115 may deliver the data units 210 to upper layers. The radio interface protocol layer may receive the data units 210 from a lower layer such as a physical layer, medium access control (MAC) layer, or radio link control (RLC) layer. The lower layers may perform packet retransmission and recovery procedures (e.g., HARQ) , and may implement multiple HARQ processes, in some cases. In some cases, the lower layers (e.g., MAC, RLC) may not perform packet reordering, and may not provide in-sequence packets to radio interface protocol layers in-between the MAC layer and upper layers (e.g., the PDCP layer) .

In the illustrated example, after receiving data units 210 in sequence, the radio interface protocol layer may receive data unit N+1 (i.e., after receiving data unit N-1) . Thus, the radio interface protocol layer may determine that data unit N is missing (e.g., a missing data unit 215) , and may start a reordering timer based on determining that data unit N is missing.

For the duration of the reordering timer, the radio interface protocol layer may avoid delivering data unit N+1 and other data units received after data unit N+1 to an upper layer before receiving data unit N (e.g., when out-of-order packet delivery to upper layers is not configured) , since the delivery of out-of-order data units to an upper layer (e.g., the IP, UDP, or TCP layer at the UE 115) may be inefficient. For example, if the missing data unit N is delayed, and the upper layer requests a retransmission of data unit N after receiving the out-of-order data units, the upper layer may receive two copies of the data unit from a base station 105 (i.e., the delayed data unit and the retransmitted data unit) and the UE 115 may transmit duplicate acknowledgements (e.g., in HARQ feedback) to the base station 105, which may be wasteful. Accordingly, data unit N+1 and other data units (i.e., data units 220) received after missing data units 215 may be stored in a reception buffer and delivered to upper layers in ascending order after the reordering timer expires or after the missing data units 215 are received. Thus, the reordering timer provides additional time to receive the missing data units 215 before declaring by the radio interface protocol layer that the missing data units are lost.

In wireless communications system 100, a multi-SIM UE 115 may use the techniques described above to avoid unnecessarily delivering out-of-order data units to upper layers, which may limit unnecessary data transmissions and HARQ feedback in wireless communications system 100. In some cases, however, while receiving data units from a base station 105 according to a first subscription at a UE 115 via a radio, the multi-SIM UE 115 may switch to communicating according to a second subscription via the radio. In such cases, if a reordering timer is running at the radio interface protocol layer for communications according to the first subscription, the reordering timer may run out while the radio is being used for communications according to the second subscription without giving the lower layers of the UE 115 a chance to receive a missing data unit. As a result, the chances that data units are delivered out-of-order to an upper layer at the UE 115 may increase, and a substantial amount of resources may be wasted for unnecessary retransmissions of data units triggered by upper layers. As described herein, multi-SIM UEs 115 in wireless communications system 100 may support efficient techniques for managing a reordering timer to improve packet delivery.

FIG. 3 illustrates an example of a wireless communications system 300 that supports packet delivery for multi-SIM UEs in accordance with aspects of the present disclosure. Wireless communications system 300 includes base station 105-a, base station 105-b, and UE 115-a, which may be examples of a base station 105 and a UE 115 described with reference to FIGs. 1 and 2. Base station 105-a and base station 105-b may communicate with UE 115-a on carriers 305. Similar to wireless communications system 100, wireless communications system 300 may be a packet-based network that operates according to a layered protocol stack. In the user plane, base station 105-a and base station 105-b may include radio access network layers including a PDCP layer 315, RLC layer 320, MAC layer 325, and PHY layer 330, and UE 115-a may include an application layer 335, TCP/UDP layer 340, IP layer 345, and corresponding radio access network layers including PDCP layer 350, RLC layer 355, MAC layer 360, and PHY layer 365. Thus, the PDCP layer 350 of the UE may be highest layer of the radio access network layers between the base stations 105-a, 105-b and the UE 115-a. Although the examples described herein relate to techniques performed at PDCP layer 350 of UE 115-a, it is to be understood that the same techniques may be implemented at another layer at UE 115-a.

UE 115-a may be an example of a multi-SIM UE and may include a first SIM 310-a and a second SIM 310-b. The first SIM 310-a may be associated with a first subscription (e.g., with a first operator) and the second SIM 310-b may be associated with a second subscription (e.g., with a second operator) . Thus, multi-SIM UE 115-a may communicate with base station 105-a according to a first subscription associated with first SIM 310-a, and multi-SIM UE 115 may communicate with base station 105-b according to a second subscription associated with a second SIM 310-b. In some cases, multi-SIM UE 115-a may communicate with the same base station according to the first subscription associated with first SIM 310-a and the second subscription associated with the second SIM 310-b.

In some examples, multi-SIM UE 115-a may include a single radio for communications with base station 105-a and 105-b. The radio may include one or more RF chains, but may support communication with only one of base station 105-a or base station 105-b at a time (e.g., may not have separately tunable RF chains capable of concurrent communication with base stations 105-a and 105-b) . Thus, the UE 115-a may tune away from communications with base station 105-a according to the first subscription if a communication event occurs between base station 105-b and UE 115-a according to the second subscription. For example, the UE 115-a may be communicating in a connected mode with base station 105-a according to the first subscription while in an idle mode for the second subscription (e.g., the UE 115-a is considered by the network associated with the second subscription to be in an idle mode) . However, paging occasions may be defined for the second subscription so that the UE 115-a can be contacted if the network associated with the second subscription has data for the UE 115-a. In addition, the UE 115-a may perform other idle-mode procedures to maintain the ability to be contacted by the network associated with the second subscription or may receive other communications. For example, communications according to the second subscription may include receiving a paging message according to the second subscription, performing a voice call according to the second subscription, performing a tracking area update according to the second subscription, transmitting or receiving a short message service (SMS) or multimedia messaging service (MMS) according to the second subscription, non-access stratum (NAS) signaling according to the second subscription, packet-switched signaling according to the second subscription, etc.

PDCP layer 350 of multi-SIM UE 115-a may use the techniques described herein to manage a reordering timer to improve packet delivery to upper layers. Specifically, PDCP layer 350 may pause a reordering timer that was started for communications according to a first subscription via radio when the radio is being used for communications according to a second subscription, . Such techniques for managing a reordering timer to improve packet delivery to upper layers are described in further detail with reference to FIGs. 4 and 5.

FIG. 4 illustrates an example timeline 400 of communications between base station 105-a and multi-SIM UE 115-a in accordance with aspects of the present disclosure. In the example of FIG. 4, multi-SIM UE 115-a may be in the process of communicating with base station 105-a according to a first subscription associated with first SIM 310-a. Specifically, PDCP layer 350 may be receiving a series of data units from base station 105-a (e.g., receiving the data units from lower layers after the data units are received from base station 105-a via a radio of the UE 115-a) according to the first subscription. At 405, PDCP layer 350 of UE 115-a may identify a missing data unit in the series of data units received from base station 105-a.

Accordingly, PDCP layer 350 may start a reordering timer 402 to provide time to receive the missing data unit before forwarding out-of-order data units to an upper layer (e.g., TCP 340) of multi-SIM UE 115-a. PDCP layer 350 may also update a variable (e.g., RX_REORD) which holds the sequence number following the sequence number of the data unit that triggered the reordering timer, and PDCP layer 350 may update a variable (e.g., RX_DELIV) which holds the sequence number of the last data unit that has not been delivered to the upper layer (if necessary) . PDCP layer 350 may then store data units received with a sequence number larger than the missing data unit, and PDCP layer 350 may wait to deliver these data units to an upper layer until the missing data unit is received or until the reordering timer 402 expires.

At 410, PDCP layer 350 may receive an indication that the radio is switching from being used for communicating with base station 105-a according to the first subscription to being used for communicating with base station 105-b according to the second subscription. In this example, PDCP layer 350 may receive an indication of the start of tune-away gap 415. As described herein, PDCP layer 350 may pause the reordering timer 402 at 410, and multi-SIM UE 310-b may enter the tune-away gap 415.

In some cases, the tune-away gap 415 may be large and if multi-SIM UE 115-a avoids delivering stored data units to the upper layer, the data units may be significantly delayed. Thus, using the techniques described herein, PDCP layer 350 may be configured to deliver stored data units to an upper layer if the tune-away gap 415 is too large.

In particular, at 410, PDCP layer 350 may start a delivery timer 420 (also referred to as a force delivery timer) . If, at 430, the delivery timer 420 expires, PDCP layer 350 may deliver the stored data units to the upper layer in ascending order (e.g., PDCP layer 350 may deliver the stored data units with sequence numbers or count values that are less than RX_REORD) and PDCP layer 350 may trigger a PDCP status report (also referred to as a data unit status report) to attempt to retrieve the missing data unit (s) . The PDCP status report may be, for example, a PDCP control PDU including information for missing data units. In some cases, PDCP layer 350 may avoid updating the RX_DELIV variable and avoid shifting the reordering window (e.g., since the missing data unit was not received) . Pausing the reordering timer 402 and starting the delivery timer 420 at the beginning of a tune-away gap may, for example, prevent data units from being delivered out-of-order at the beginning of the tune-away gap (if, for example the reordering timer 402 is about to expire) , while still delivering stored data units without significant delay if the tune-away gap is too large. In some cases, the duration of the delivery timer 420 may be substantially longer than the duration of the reordering timer 402. For example, the duration of the delivery timer may be more than one second, and the duration may be selected to force delivery of any received data units for long tune-away gaps to prevent more substantial impacts to higher layers such as TCP retransmission time-outs. Although in the illustrated example, the missing data unit is detected at 405 prior to the indication of the tune-away gap 415, alternatively the missing data unit may be detected after the start of the tune-away gap 415. In this case, the PDCP layer 350 may start and pause the reordering timer 402 and start the delivery timer 420 when a first instance of a missing data unit is detected within a tune-away gap.

At 430, PDCP layer 350 may receive an indication that the RF chain is switching from being used for communicating with base station 105-b according to the second subscription associated with second SIM 310-b to being used for communicating with base station 105-a according to the first subscription associated with first SIM 310-a. Based on the indication at 430, PDCP layer 350 may resume the reordering timer 402 and, in other examples where the delivery timer 420 is running, PDCP layer 350 may stop the delivery timer 420. PDCP layer 350 may then continue to receive data units from base station 105-a according to the first subscription.

In some cases, since the tune-away gap 415 may cause additional data units to be missing (i.e., as the RF chain was not available to receive data units according to the first subscription) , PDCP layer 350 may be configured to extend the reordering timer 402 within a reordering timer extension duration 435 after the tune-away gap 415. That is, reordering timer 402 (e.g., started before the duration 435 or within the duration 435) may be extended (or overwritten with a larger value) . As a result, PDCP layer 350 may have sufficient time to receive data units missed during tune-away gap 415. At 440, when the extended reordering timer expires, PDCP layer 350 may deliver stored data units to upper layers and may revert the reordering timer duration (i.e., to a configured duration) . Alternatively, if the missing data unit (s) are received prior to the expiration of the extended reordering timer at 440, then the data unit (s) are delivered in sequence and the reordering timer is reset.

FIG. 5 illustrates an example timeline 500 of communications between base station 105-a and multi-SIM UE 115-a in accordance with aspects of the present disclosure. In the example of FIG. 5, multi-SIM UE 115-a may be in the process of communicating with base station 105-a according to a first subscription associated with first SIM 310-a. Specifically, PDCP layer 350 may be receiving a series of data units from base station 105-a (e.g., receiving the data units from lower layers after the data units are received from base station 105-a via a radio of the UE 115-a) according to the first subscription. At 505, PDCP layer 350 of UE 115-a may identify a missing data unit in the series of data units received from base station 105-a.

Accordingly, PDCP layer 350 may start a reordering timer 502 to provide time to receive the missing data unit before forwarding out-of-order data units to an upper layer (e.g., TCP 340) of multi-SIM UE 115-a. PDCP layer 350 may also update a variable (e.g., RX_REORD) which holds the sequence number following the sequence number of the data unit that triggered the reordering timer, and PDCP layer 350 may update a variable (e.g., RX_DELIV) which holds the sequence number of the last data unit that has not been delivered to the upper layer. PDCP layer 350 may then store data units received with a sequence number larger than the missing data unit, and PDCP layer 350 may wait to deliver these data units to an upper layer until the missing data unit is received or until the reordering timer 502 expires.

At 510, PDCP layer 350 may receive an indication that the radio is switching from being used for communicating with base station 105-a according to the first subscription associated with first SIM 310-a to being used for communicating with base station 105-b according to the second subscription associated with second SIM 310-b. That is, PDCP layer 350 may receive an indication of the start of tune-away gap 515. Thus, as described herein, PDCP layer 350 may pause the reordering timer 502 at 510 and start a delivery timer 520. In the example of FIG. 5, at 525, PDCP layer 350 may receive additional data units, including the missing data unit, after receiving the indication at 510. For instance, there may be a time delay between receiving the indication at 510 and switching the radio for communicating with base station 105-b according to the second subscription, or data units may be in process at lower layers, and the PDCP layer 350 may receive the additional data units in this delay. Thus, at 530, PDCP layer 350 may stop and reset the delivery timer 520 and the reordering timer 502 since there may be no missing data units (e.g., no data units with a sequence number before RX_REORD that have not been received) , and PDCP layer 350 may deliver the received data units to an upper layer.

At 535, the delivery timer may not be running and may not have expired previously, and PDCP layer 350 may identify another missing data unit. As a result of identifying a missing data unit within a tune-away gap, PDCP layer 350 may start and pause the reordering timer 502 and start the delivery timer 520 at 535. At 545, PDCP layer 350 may receive an indication that the radio is switching from being used for communicating with base station 105-b according to the second subscription associated with second SIM 310-b to being used for communicating with base station 105-a according to the first subscription associated with first SIM 310-a. Thus, at 545, PDCP layer 350 may resume the reordering timer 502 and may stop the delivery timer 520. PDCP layer 350 may also extend the reordering timer 502 within reordering timer extension duration 530 after the tune-away gap 515. PDCP layer 350 may then continue to receive data units from base station 105-a according to the first subscription.

In some cases, at 545, PDCP layer 545 may also start a wait timer 540. The wait timer 540 may be used to expedite data recovery when data recovery processes at RLC 355 or MAC 360 are slow. Thus, in this example, when the wait timer 540 expires at 555, PDCP layer 350 may trigger a status report to recover missing data unit (s) . In other examples, if a status report was already triggered to recover the missing data unit (s) (e.g., after the delivery timer 520 expired) , PDCP layer 350 may stop the wait timer. At 560, when the extended reordering timer expires, PDCP layer 350 may deliver stored data units to upper layers and may revert the reordering timer duration (i.e., to a configured duration) . Alternatively, if the missing data unit (s) are received prior to the expiration of the extended reordering timer at 560, then the data unit (s) are delivered in sequence and the reordering timer is reset.

FIG. 6 illustrates an example of a flow diagram 600 that supports packet delivery for multi-SIM UEs in accordance with aspects of the present disclosure. The processes described with reference to FIG. 6 may be performed at PDCP layer 350 of multi-SIM UE 115-a after receiving a new data unit from base station 105-a. Although the flow diagram provides a limited set of process to be performed upon receiving a new data unit from a base station 105-a, it is to be understood that additional processes may be performed by multi-SIM UE 115-a after receiving the new data unit from base station 105-a. The reordering timer and delivery timer described with reference to FIG. 6 may be examples of the corresponding timers described with reference to FIGs. 4 and 5. In this example, the delivery timer may not be running or may not have expired previously (e.g., a status report may not have been triggered for a missing data unit) . The techniques described with reference to FIG. 6 may be performed at PDCP layer 350 or another layer at multi-SIM UE 115-a.

Flow diagram 600 begins at 605 and proceeds to block 610. At block 610, PDCP layer 350 may receive a new data unit from base station 105-a. PDCP layer 350 may determine that the data unit is new (i.e., not a duplicate of a previously received data unit) based on the sequence number of the data unit. At 615, PDCP layer 350 may then update the stored RCVD_COUNT variable based on the sequence number of the data unit. The RCVD_COUNT variable may hold the value of the sequence number of the last data unit received. If RCVD_COUNT is greater than or equal to RX_NEXT, PDCP layer 350 may update RX_NEXT to RCVD_COUNT+1. Thus, the RX_NEXT may hold the value of the sequence number of the next data unit to be received from the base station (e.g., excluding missing data units) .

At 620, PDCP layer 350 may determine whether RCVD_COUNT is equal to RX_DELIV, where RX_DELIV holds the value of the sequence number of the first data unit (e.g., PDCP SDU) which has not been delivered to upper layers. If RCVD_COUNT is equal to RX_DELIV, PDCP layer 350 may determine that a data unit that was previously missing has been received, and, at 625, PDCP layer 350 may deliver the stored data units to upper layers in ascending sequence starting from the data unit with a sequence number equal to RX_DELIV. Otherwise, if RCVD_COUNT is not equal to RX_DELIV, PDCP layer 350 may determine that the data unit with a sequence number equal to RX_DELIV may still be missing, and PDCP layer 350 may avoid delivering the stored data units to upper layers.

At 630, PDCP layer 350 may determine whether a reordering timer at PDCP layer 350 is paused and whether RX_DELIV is greater than or equal to RX_REORD, where RX_REORD holds the value of the sequence number following the sequence number of the data unit that triggered the reordering timer. If the reordering timer at PDCP layer 350 is paused and RX_DELIV is greater than or equal to RX_REORD, PDCP layer 350 may have received all missing data units, and, at 635, PDCP layer 350 may stop and reset the reordering timer and delivery timer. Otherwise, if the reordering timer at PDCP layer 350 is paused and RX_DELIV is less than RX_REORD, PDCP layer 350 may not have received all missing data units, and PDCP layer 350 may leave the reordering timer and the delivery timer running.

At 640, PDCP layer 350 may determine whether a reordering timer at PDCP layer 350 is running or paused and whether RX_DELIV is less than RX_NEXT. If the reordering timer is not running or paused and RX_DELIV is less than RX_NEXT, a data unit may be missing and the reordering timer may not have been started. Thus, at 645, PDCP layer 350 may update RX_REORD to RX_NEXT (i.e., to the sequence number following the sequence number of the data unit that is triggering the reordering timer) , PDCP layer 350 may start and pause the reordering timer, and PDCP layer 350 may start the delivery timer. PDCP layer 350 may then continue to 650 where PDCP layer 350 may end data unit processing for the new data unit described in this example.

The examples described above are related to efficient techniques for implementing an extended reordering timer (tExtReord) , a delivery timer, and a wait timer. The extended reordering timer may be used to provide sufficient time for RLC recovery when a missing data unit is identified during a tune-away gap or after a tune-away gap. The duration of the extended reordering timer may be adaptive based on the length of a tune-away gap and may not be too large to avoid a negative impact on an upper layer due to large delays. Further, the duration of the extended reordering timer may be different for a standalone NR deployment and a non-standalone NR deployment. The delivery timer may be used to avoid long upper layer delays (e.g., such as a TCP retransmission timeout (RTO) timer expiring) . The duration of a delivery timer may be large enough to avoid frequent out-of-order delivery for short tune-away gaps, which may have a negative impact on a TCP window size. In some cases, the duration of a delivery timer may be based on the average TCP round trip time (RTT) estimation and/or may be calculated as N×tReordering or RLC tPolling× maxRLCreTX.

The wait timer may be used to allow enough time for RLC/HARQ retransmissions before triggering a PDCP status report. In some cases, the duration of the wait timer may be set as half the duration of the reordering timer or the RLC reassembly timer. As with the reordering timer, the duration of the wait timer may be different for a standalone NR deployment and a non-standalone NR deployment. As discussed above, in some examples, a PDCP status report may be triggered when the wait timer expires. In other examples, a PDCP status report may be triggered after the wait timer expires when the gap between a next data unit to be received (i.e., RX_NEXT) and the first data unit not delivered to an upper layer (i.e., RX_DELIV) is sufficiently large. That is, the PDCP status report may be triggered after the wait timer expires if RX_NEXT minus RX_DELIV is greater than a threshold PDCP hole length. The value of the threshold PDCP hole length may be set as (tExtReord-tWait) × avg data units/ms. Thus, the PDCP status report may be triggered if it may be challenging to receive all missing data units before the reordering timer expires.

FIG. 7 shows a block diagram 700 of a device 705 that supports packet delivery for multi-SIM UEs in accordance with aspects of the present disclosure. The device 705 may be an example of aspects of a UE 115 as described herein. The device 705 may include a receiver 710, a communications manager 715, and a transmitter 720. The device 705 may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses) . The communications manager 715 may perform the techniques described below at a radio interface protocol layer of device 705.

The receiver 710 may receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to packet delivery for multi-SIM UEs, etc. ) . Information may be passed on to other components of the device 705. The receiver 710 may be an example of aspects of the transceiver 1020 described with reference to FIG. 10. The receiver 710 may utilize a single antenna or a set of antennas.

The communications manager 715 may receive a subset of a series of data units from a first base station via an RF chain according to a first subscription associated with a first SIM of the UE, start a reordering timer for the series of data units upon identifying at least one missing data unit in the received subset of the series of data units, pause the reordering timer based on receiving the indication, receive, from a physical layer, an indication that the RF chain is being used for communicating with a second base station according to a second subscription associated with a second SIM of the UE, and deliver the subset of the series of data units to a higher layer based on the reordering timer. The communications manager 715 may be an example of aspects of the communications manager 1010 described herein.

The communications manager 715, or its sub-components, may be implemented in hardware, code (e.g., software or firmware) executed by a processor, or any combination thereof. If implemented in code executed by a processor, the functions of the communications manager 715, or its sub-components may be executed by a general-purpose processor, a DSP, an application-specific integrated circuit (ASIC) , a FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described in the present disclosure.

The communications manager 715, or its sub-components, may be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations by one or more physical components. In some examples, the communications manager 715, or its sub-components, may be a separate and distinct component in accordance with various aspects of the present disclosure. In some examples, the communications manager 715, or its sub-components, may be combined with one or more other hardware components, including but not limited to an input/output (I/O) component, a transceiver, a network server, another computing device, one or more other components described in the present disclosure, or a combination thereof in accordance with various aspects of the present disclosure.

The transmitter 720 may transmit signals generated by other components of the device 705. In some examples, the transmitter 720 may be collocated with a receiver 710 in a transceiver module. For example, the transmitter 720 may be an example of aspects of the transceiver 1020 described with reference to FIG. 10. The transmitter 720 may utilize a single antenna or a set of antennas.

FIG. 8 shows a block diagram 800 of a device 805 that supports packet delivery for multi-SIM UEs in accordance with aspects of the present disclosure. The device 805 may be an example of aspects of a device 705 or a UE 115 as described herein. The device 805 may include a receiver 810, a communications manager 815, and a transmitter 840. The device 805 may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses) . The communications manager 815may perform the techniques described below at a radio interface protocol layer of device 805.

The receiver 810 may receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to packet delivery for multi-SIM UEs, etc. ) . Information may be passed on to other components of the device 805. The receiver 810 may be an example of aspects of the transceiver 1020 described with reference to FIG. 10. The receiver 810 may utilize a single antenna or a set of antennas.

The communications manager 815 may be an example of aspects of the communications manager 715 as described herein. The communications manager 815 may include a data unit receiver 820, a reordering timer manager 825, a tune-away gap manager 830, and a data unit delivery manager 835. The communications manager 815 may be an example of aspects of the communications manager 1010 described herein.

The data unit receiver 820 may receive a subset of a series of data units from a first base station via an RF chain according to a first subscription associated with a first SIM of the UE. The reordering timer manager 825 may start a reordering timer for the series of data units upon identifying at least one missing data unit in the received subset of the series of data units and pause the reordering timer based on receiving the indication. The tune-away gap manager 830 may receive, from a physical layer, an indication that the RF chain is being used for communicating with a second base station according to a second subscription associated with a second SIM of the UE. The data unit delivery manager 835 may deliver the subset of the series of data units to a higher layer based on the reordering timer.

The transmitter 840 may transmit signals generated by other components of the device 805. In some examples, the transmitter 840 may be collocated with a receiver 810 in a transceiver module. For example, the transmitter 840 may be an example of aspects of the transceiver 1020 described with reference to FIG. 10. The transmitter 840 may utilize a single antenna or a set of antennas.

FIG. 9 shows a block diagram 900 of a communications manager 905 that supports packet delivery for multi-SIM UEs in accordance with aspects of the present disclosure. The communications manager 905 may be an example of aspects of a communications manager 715, a communications manager 815, or a communications manager 1010 described herein. . The communications manager 905 may include a data unit receiver 910, a reordering timer manager 915, a tune-away gap manager 920, a data unit delivery manager 925, a delivery timer manager 930, a data unit storage manager 935, a data unit status report manager 940, and a wait timer manager 945. Each of these modules may communicate, directly or indirectly, with one another (e.g., via one or more buses) .

The data unit receiver 910 may receive a subset of a series of data units from a first base station via an RF chain according to a first subscription associated with a first SIM of the UE. The reordering timer manager 915 may start a reordering timer for the series of data units upon identifying at least one missing data unit in the received subset of the series of data units. The tune-away gap manager 920 may receive, from a physical layer, an indication that the RF chain is being used for communicating with a second base station according to a second subscription associated with a second SIM of the UE. The reordering timer manager 915 may pause the reordering timer based on receiving the indication. The data unit delivery manager 925 may deliver the subset of the series of data units to a higher layer based on the reordering timer.

The delivery timer manager 930 may start a delivery timer upon receiving the indication when the at least one missing data unit is identified prior to receiving the indication or upon identifying the at least one missing data unit in the received subset of the series of data units when the at least one missing data unit is identified after receiving the indication. The data unit storage manager 935 may store the subset of the series of data units received from the first base station, and the data unit delivery manager 925 may deliver the stored subset of the series of data units in ascending order to the higher layer after the delivery timer expires. The data unit status report manager 940 may trigger a data unit status report after the delivery timer expires.

In some examples, the data unit storage manager 935 may store the subset of the series of data units received from the first base station, the data unit receiver 910 may receive the at least one missing data unit before the delivery timer expires, the data unit delivery manager 925 may deliver the stored subset of the series of data units in ascending order to the higher layer including the at least one missing data unit, the reordering timer manager 915 may reset the reordering timer, and the delivery timer manager 930 may reset the delivery timer. In some cases, the reordering timer is started prior to receiving the indication, and the reordering timer is paused upon receiving the indication. In some cases, the indication is received prior to identifying the at least one missing data unit, and the reordering timer is started and paused upon identifying the at least one missing data unit.

In some examples, the tune-away gap manager 920 may receive, from the physical layer, a second indication that the RF chain is switching from being used for communicating with the second base station according to the second subscription to being used for communicating with the first base station according to the first subscription. In some examples, the reordering timer manager 915 may extend the reordering timer upon receiving the second indication and resume the reordering timer. In some examples, the reordering timer manager 915 may revert the reordering timer to a configured value after the reordering timer expires. The wait timer manager 945 may start a wait timer upon receiving the second indication. In some examples, the data unit status report manager 940 may trigger a data unit status report after the wait timer expires when the radio interface protocol layer fails to receive the at least one missing data unit. In some examples, the data unit status report manager 940 may determine that a data unit status report was triggered after the expiration of a delivery timer, and the wait timer manager 945 may stop the wait timer based on the determination.

FIG. 10 shows a diagram of a system 1000 including a device 1005 that supports packet delivery for multi-SIM UEs in accordance with aspects of the present disclosure. The device 1005 may be an example of or include the components of device 705, device 805, or a UE 115 as described herein. The device 1005 may include components for bi-directional voice and data communications including components for transmitting and receiving communications, including a communications manager 1010, an I/O controller 1015, a transceiver 1020, an antenna 1025, memory 1030, and a processor 1040. These components may be in electronic communication via one or more buses (e.g., bus 1045) .

The communications manager 1010 may receive a subset of a series of data units from a first base station via an RF chain according to a first subscription associated with a first SIM of the UE, start a reordering timer for the series of data units upon identifying at least one missing data unit in the received subset of the series of data units, pause the reordering timer based on receiving the indication, receive, from a physical layer, an indication that the RF chain is being used for communicating with a second base station according to a second subscription associated with a second SIM of the UE, and deliver the subset of the series of data units to a higher layer based on the reordering timer.

The I/O controller 1015 may manage input and output signals for the device 1005. The I/O controller 1015 may also manage peripherals not integrated into the device 1005. In some cases, the I/O controller 1015 may represent a physical connection or port to an external peripheral. In some cases, the I/O controller 1015 may utilize an operating system such as

or another known operating system. In other cases, the I/O controller 1015 may represent or interact with a modem, a keyboard, a mouse, a touchscreen, or a similar device. In some cases, the I/O controller 1015 may be implemented as part of a processor. In some cases, a user may interact with the device 1005 via the I/O controller 1015 or via hardware components controlled by the I/O controller 1015.

The transceiver 1020 may communicate bi-directionally, via one or more antennas, wired, or wireless links as described above. For example, the transceiver 1020 may represent a wireless transceiver and may communicate bi-directionally with another wireless transceiver. The transceiver 1020 may also include a modem to modulate the packets and provide the modulated packets to the antennas for transmission, and to demodulate packets received from the antennas.

In some cases, the wireless device may include a single antenna 1025. However, in some cases the device may have more than one antenna 1025, which may be capable of concurrently transmitting or receiving multiple wireless transmissions.

The memory 1030 may include RAM and ROM. The memory 1030 may store computer-readable, computer-executable code 1035 including instructions that, when executed, cause the processor to perform various functions described herein. In some cases, the memory 1030 may contain, among other things, a BIOS which may control basic hardware or software operation such as the interaction with peripheral components or devices.

The processor 1040 may include an intelligent hardware device, (e.g., a general-purpose processor, a DSP, a CPU, a microcontroller, an ASIC, an FPGA, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof) . In some cases, the processor 1040 may be configured to operate a memory array using a memory controller. In other cases, a memory controller may be integrated into the processor 1040. The processor 1040 may be configured to execute computer-readable instructions stored in a memory (e.g., the memory 1030) to cause the device 1005 to perform various functions (e.g., functions or tasks supporting packet delivery for multi-SIM UEs) .

The code 1035 may include instructions to implement aspects of the present disclosure, including instructions to support wireless communications. The code 1035 may be stored in a non-transitory computer-readable medium such as system memory or other type of memory. In some cases, the code 1035 may not be directly executable by the processor 1040 but may cause a computer (e.g., when compiled and executed) to perform functions described herein.

FIG. 11 shows a flowchart illustrating a method 1100 that supports packet delivery for multi-SIM UEs in accordance with aspects of the present disclosure. The operations of method 1100 may be implemented at a radio interface protocol layer (e.g., PDCP layer) of a UE 115 as described herein. The operations of method 1100 may be performed by a communications manager as described with reference to FIGs. 7 through 10. In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the functions described below. Additionally or alternatively, a UE may perform aspects of the functions described below using special-purpose hardware.

At 1105, the radio interface protocol layer may receive a subset of a series of data units from a first base station via an RF chain according to a first subscription associated with a first SIM of the UE. The operations of 1105 may be performed according to the methods described herein. In some examples, aspects of the operations of 1105 may be performed by a data unit receiver as described with reference to FIGs. 7 through 10.

At 1110, the radio interface protocol layer may start a reordering timer for the series of data units upon identifying at least one missing data unit in the received subset of the series of data units. The operations of 1110 may be performed according to the methods described herein. In some examples, aspects of the operations of 1110 may be performed by a reordering timer manager as described with reference to FIGs. 7 through 10.

At 1115, the radio interface protocol layer may receive, from a physical layer, an indication that the RF chain is being used for communicating with a second base station according to a second subscription associated with a second SIM of the UE. The operations of 1115 may be performed according to the methods described herein. In some examples, aspects of the operations of 1115 may be performed by a tune-away gap manager as described with reference to FIGs. 7 through 10.

At 1120, the radio interface protocol layer may pause the reordering timer based on receiving the indication. The operations of 1120 may be performed according to the methods described herein. In some examples, aspects of the operations of 1120 may be performed by a reordering timer manager as described with reference to FIGs. 7 through 10.

At 1125, the radio interface protocol layer may deliver the subset of the series of data units to a higher layer based on the reordering timer. For instance, the radio interface protocol layer may deliver the subset of the series of data units to a higher layer when the at least one missing data unit is received or when the reordering timer expires. The operations of 1125 may be performed according to the methods described herein. In some examples, aspects of the operations of 1125 may be performed by a data unit delivery manager as described with reference to FIGs. 7 through 10.

FIG. 12 shows a flowchart illustrating a method 1200 that supports packet delivery for multi-SIM UEs in accordance with aspects of the present disclosure. The operations of method 1200 may be implemented at a radio interface protocol layer of a UE 115 as described herein. The operations of method 1200 may be performed by a communications manager as described with reference to FIGs. 7 through 10. In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the functions described below. Additionally or alternatively, a UE may perform aspects of the functions described below using special-purpose hardware.

At 1205, the radio interface protocol layer may receive a subset of a series of data units from a first base station via an RF chain according to a first subscription associated with a first SIM of the UE. The operations of 1205 may be performed according to the methods described herein. In some examples, aspects of the operations of 1205 may be performed by a data unit receiver as described with reference to FIGs. 7 through 10.

At 1210, the radio interface protocol layer may receive, from a physical layer, an indication that the RF chain is being used for communicating with a second base station according to a second subscription associated with a second SIM of the UE. The operations of 1210 may be performed according to the methods described herein. In some examples, aspects of the operations of 1210 may be performed by a tune-away gap manager as described with reference to FIGs. 7 through 10.

At 1215, the radio interface protocol layer may start and pause a reordering timer for the series of data units upon identifying at least one missing data unit in the received subset of the series of data units. The operations of 1215 may be performed according to the methods described herein. In some examples, aspects of the operations of 1215 may be performed by a reordering timer manager as described with reference to FIGs. 7 through 10.

At 1220, the radio interface protocol layer may deliver the subset of the series of data units to a higher layer based on the reordering timer. For instance, the radio interface protocol layer may deliver the subset of the series of data units to a higher layer when the at least one missing data unit is received or when the reordering timer expires. The operations of 1220 may be performed according to the methods described herein. In some examples, aspects of the operations of 1220 may be performed by a data unit delivery manager as described with reference to FIGs. 7 through 10.

It should be noted that the methods described above describe possible implementations, and that the operations and the steps may be rearranged or otherwise modified and that other implementations are possible. Further, aspects from two or more of the methods may be combined.

Techniques described herein may be used for various wireless communications systems such as code division multiple access (CDMA) , time division multiple access (TDMA) , frequency division multiple access (FDMA) , orthogonal frequency division multiple access (OFDMA) , single carrier frequency division multiple access (SC-FDMA) , and other systems. A CDMA system may implement a radio technology such as CDMA2000, Universal Terrestrial Radio Access (UTRA) , etc. CDMA2000 covers IS-2000, IS-95, and IS-856 standards. IS-2000 Releases may be commonly referred to as CDMA2000 1X, 1X, etc. IS-856 (TIA-856) is commonly referred to as CDMA2000 1xEV-DO, High Rate Packet Data (HRPD) , etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. A TDMA system may implement a radio technology such as Global System for Mobile Communications (GSM) .

An OFDMA system may implement a radio technology such as Ultra Mobile Broadband (UMB) , Evolved UTRA (E-UTRA) , Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi) , IEEE 802.16 (WiMAX) , IEEE 802.20, Flash-OFDM, etc. UTRA and E-UTRA are part of Universal Mobile Telecommunications System (UMTS) . LTE, LTE-A, and LTE-A Pro are releases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, LTE-A Pro, NR, and GSM are described in documents from the organization named “3rd Generation Partnership Project” (3GPP) . CDMA2000 and UMB are described in documents from an organization named “3rd Generation Partnership Project 2” (3GPP2) . The techniques described herein may be used for the systems and radio technologies mentioned above as well as other systems and radio technologies. While aspects of an LTE, LTE-A, LTE-A Pro, or NR system may be described for purposes of example, and LTE, LTE-A, LTE-A Pro, or NR terminology may be used in much of the description, the techniques described herein are applicable beyond LTE, LTE-A, LTE-A Pro, or NR applications.

A macro cell generally covers a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs 115 with service subscriptions with the network provider. A small cell may be associated with a lower-powered base station 105, as compared with a macro cell, and a small cell may operate in the same or different (e.g., licensed, unlicensed, etc. ) frequency bands as macro cells. Small cells may include pico cells, femto cells, and micro cells according to various examples. A pico cell, for example, may cover a small geographic area and may allow unrestricted access by UEs 115 with service subscriptions with the network provider. A femto cell may also cover a small geographic area (e.g., a home) and may provide restricted access by UEs 115 having an association with the femto cell (e.g., UEs 115 in a closed subscriber group (CSG) , UEs 115 for users in the home, and the like) . An eNB for a macro cell may be referred to as a macro eNB. An eNB for a small cell may be referred to as a small cell eNB, a pico eNB, a femto eNB, or a home eNB. An eNB may support one or multiple (e.g., two, three, four, and the like) cells, and may also support communications using one or multiple component carriers.

The wireless communications system 100 or systems described herein may support synchronous or asynchronous operation. For synchronous operation, the base stations 105 may have similar frame timing, and transmissions from different base stations 105 may be approximately aligned in time. For asynchronous operation, the base stations 105 may have different frame timing, and transmissions from different base stations 105 may not be aligned in time. The techniques described herein may be used for either synchronous or asynchronous operations.

Information and signals described herein may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

The various illustrative blocks and modules described in connection with the disclosure herein may be implemented or performed with a general-purpose processor, a digital signal processor (DSP) , an application-specific integrated circuit (ASIC) , a field-programmable gate array (FPGA) or other programmable logic device (PLD) , discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration) .

The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Other examples and implementations are within the scope of the disclosure and appended claims. For example, due to the nature of software, functions described above can be implemented using software executed by a processor, hardware, firmware, hardwiring, or combinations of any of these. Features implementing functions may also be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations.

Computer-readable media includes both non-transitory computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A non-transitory storage medium may be any available medium that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, non-transitory computer-readable media may include random-access memory (RAM) , read-only memory (ROM) , electrically erasable programmable read only memory (EEPROM) , flash memory, compact disk (CD) ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other non-transitory medium that can be used to carry or store desired program code means in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL) , or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk and disc, as used herein, include CD, laser disc, optical disc, digital versatile disc (DVD) , floppy disk and Blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above are also included within the scope of computer-readable media.

As used herein, including in the claims, “or” as used in a list of items (e.g., a list of items prefaced by a phrase such as “at least one of” or “one or more of” ) indicates an inclusive list such that, for example, a list of at least one of A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C) . Also, as used herein, the phrase “based on” shall not be construed as a reference to a closed set of conditions. For example, an exemplary step that is described as “based on condition A” may be based on both a condition A and a condition B without departing from the scope of the present disclosure. In other words, as used herein, the phrase “based on” shall be construed in the same manner as the phrase “based at least in part on. ”

In the appended figures, similar components or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If just the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label, or other subsequent reference label.

The description set forth herein, in connection with the appended drawings, describes example configurations and does not represent all the examples that may be implemented or that are within the scope of the claims. The term “exemplary” used herein means “serving as an example, instance, or illustration, ” and not “preferred” or “advantageous over other examples. ” The detailed description includes specific details for the purpose of providing an understanding of the described techniques. These techniques, however, may be practiced without these specific details. In some instances, well-known structures and devices are shown in block diagram form in order to avoid obscuring the concepts of the described examples.

The description herein is provided to enable a person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the scope of the disclosure. Thus, the disclosure is not limited to the examples and designs described herein, but is to be accorded the broadest scope consistent with the principles and novel features disclosed herein.

Claims

A method for wireless communication at a radio interface protocol layer of a user equipment (UE) , comprising:

receiving a subset of a series of data units from a first base station via a radio frequency (RF) chain according to a first subscription associated with a first subscriber identity module (SIM) of the UE;

starting a reordering timer for the series of data units upon identifying at least one missing data unit in the received subset of the series of data units;

receiving, from a physical layer, an indication that the RF chain is being used for communicating with a second base station according to a second subscription associated with a second SIM of the UE;

pausing the reordering timer based at least in part on receiving the indication; and

delivering the subset of the series of data units to a higher layer based at least in part on the reordering timer.
The method of claim 1, further comprising:

starting a delivery timer upon receiving the indication when the at least one missing data unit is identified prior to receiving the indication or upon identifying the at least one missing data unit in the received subset of the series of data units when the at least one missing data unit is identified after receiving the indication.
The method of claim 2, further comprising:

storing the subset of the series of data units received from the first base station; and

delivering the stored subset of the series of data units in ascending order to the higher layer after the delivery timer expires.
The method of claim 2, further comprising:

triggering a data unit status report after the delivery timer expires.
The method of claim 2, further comprising:

storing the subset of the series of data units received from the first base station;

receiving the at least one missing data unit before the delivery timer expires;

delivering the stored subset of the series of data units in ascending order to the higher layer including the at least one missing data unit; and

resetting the delivery timer and the reordering timer.
The method of claim 1, wherein the reordering timer is started prior to receiving the indication, and wherein the reordering timer is paused upon receiving the indication.
The method of claim 1, wherein the indication is received prior to identifying the at least one missing data unit, and wherein the reordering timer is started and paused upon identifying the at least one missing data unit.
The method of claim 1, further comprising:

receiving, from the physical layer, a second indication that the RF chain is switching from being used for communicating with the second base station according to the second subscription to being used for communicating with the first base station according to the first subscription.
The method of claim 8, further comprising:

extending the reordering timer upon receiving the second indication; and

resuming the reordering timer.
The method of claim 9, further comprising:

reverting the reordering timer to a configured value after the reordering timer expires.
The method of claim 8, further comprising:

starting a wait timer upon receiving the second indication.
The method of claim 11, further comprising:

triggering a data unit status report after the wait timer expires when the radio interface protocol layer fails to receive the at least one missing data unit.
The method of claim 11, further comprising:

determining that a data unit status report was triggered after the expiration of a delivery timer; and

stopping the wait timer based at least in part on the determination.
An apparatus for wireless communication at a radio interface protocol layer of a user equipment (UE) , comprising:

a processor,

memory in electronic communication with the processor; and

instructions stored in the memory and executable by the processor to cause the apparatus to:

receive a subset of a series of data units from a first base station via a radio frequency (RF) chain according to a first subscription associated with a first subscriber identity module (SIM) of the UE;

start a reordering timer for the series of data units upon identifying at least one missing data unit in the received subset of the series of data units;

receive, from a physical layer, an indication that the RF chain is being used for communicating with a second base station according to a second subscription associated with a second SIM of the UE;

pause the reordering timer based at least in part on receiving the indication; and

deliver the subset of the series of data units to a higher layer based at least in part on the reordering timer.
The apparatus of claim 14, wherein the instructions are further executable by the processor to cause the apparatus to:

start a delivery timer upon receiving the indication when the at least one missing data unit is identified prior to receiving the indication or upon identifying the at least one missing data unit in the received subset of the series of data units when the at least one missing data unit is identified after receiving the indication.
The apparatus of claim 15, wherein the instructions are further executable by the processor to cause the apparatus to:

store the subset of the series of data units received from the first base station; and

deliver the stored subset of the series of data units in ascending order to the higher layer after the delivery timer expires.
The apparatus of claim 15, wherein the instructions are further executable by the processor to cause the apparatus to:

trigger a data unit status report after the delivery timer expires.
The apparatus of claim 15, wherein the instructions are further executable by the processor to cause the apparatus to:

store the subset of the series of data units received from the first base station;

receive the at least one missing data unit before the delivery timer expires;

deliver the stored subset of the series of data units in ascending order to the higher layer including the at least one missing data unit; and

reset the delivery timer and the reordering timer.
The apparatus of claim 14, wherein the reordering timer is started prior to receiving the indication, and wherein the reordering timer is paused upon receiving the indication.
The apparatus of claim 14, wherein the indication is received prior to identifying the at least one missing data unit, and wherein the reordering timer is started and paused upon identifying the at least one missing data unit.
The apparatus of claim 14, wherein the instructions are further executable by the processor to cause the apparatus to:

receive, from the physical layer, a second indication that the RF chain is switching from being used for communicating with the second base station according to the second subscription to being used for communicating with the first base station according to the first subscription.
The apparatus of claim 21, wherein the instructions are further executable by the processor to cause the apparatus to:

extend the reordering timer upon receiving the second indication; and

resume the reordering timer.
The apparatus of claim 22, wherein the instructions are further executable by the processor to cause the apparatus to:

revert the reordering timer to a configured value after the reordering timer expires.
The apparatus of claim 21, wherein the instructions are further executable by the processor to cause the apparatus to:

start a wait timer upon receiving the second indication.
The apparatus of claim 24, wherein the instructions are further executable by the processor to cause the apparatus to:

trigger a data unit status report after the wait timer expires when the radio interface protocol layer fails to receive the at least one missing data unit.
The apparatus of claim 24, wherein the instructions are further executable by the processor to cause the apparatus to:

determine that a data unit status report was triggered after the expiration of a delivery timer; and

stop the wait timer based at least in part on the determination.
An apparatus for wireless communication at a radio interface protocol layer of a user equipment (UE) , comprising:

means for receiving a subset of a series of data units from a first base station via a radio frequency (RF) chain according to a first subscription associated with a first subscriber identity module (SIM) of the UE;

means for starting a reordering timer for the series of data units upon identifying at least one missing data unit in the received subset of the series of data units;

means for receiving, from a physical layer, an indication that the RF chain is being used for communicating with a second base station according to a second subscription associated with a second SIM of the UE;

means for pausing the reordering timer based at least in part on receiving the indication; and

means for delivering the subset of the series of data units to a higher layer based at least in part on the reordering timer.
The apparatus of claim 27, further comprising:

means for starting a delivery timer upon receiving the indication when the at least one missing data unit is identified prior to receiving the indication or upon identifying the at least one missing data unit in the received subset of the series of data units when the at least one missing data unit is identified after receiving the indication.
The apparatus of claim 28, further comprising:

means for storing the subset of the series of data units received from the first base station; and

means for delivering the stored subset of the series of data units in ascending order to the higher layer after the delivery timer expires.
The apparatus of claim 28, further comprising:

means for triggering a data unit status report after the delivery timer expires.
The apparatus of claim 28, further comprising:

means for storing the subset of the series of data units received from the first base station;

means for receiving the at least one missing data unit before the delivery timer expires;

means for delivering the stored subset of the series of data units in ascending order to the higher layer including the at least one missing data unit; and

means for resetting the delivery timer and the reordering timer.
The apparatus of claim 27, wherein the reordering timer is started prior to receiving the indication, and wherein the reordering timer is paused upon receiving the indication.
The apparatus of claim 27, wherein the indication is received prior to identifying the at least one missing data unit, and wherein the reordering timer is started and paused upon identifying the at least one missing data unit.
The apparatus of claim 27, further comprising:

means for receiving, from the physical layer, a second indication that the RF chain is switching from being used for communicating with the second base station according to the second subscription to being used for communicating with the first base station according to the first subscription.
The apparatus of claim 34, further comprising:

means for extending the reordering timer upon receiving the second indication; and

means for resuming the reordering timer.
The apparatus of claim 35, further comprising:

means for reverting the reordering timer to a configured value after the reordering timer expires.
The apparatus of claim 34, further comprising:

means for starting a wait timer upon receiving the second indication.
The apparatus of claim 37, further comprising:

means for triggering a data unit status report after the wait timer expires when the radio interface protocol layer fails to receive the at least one missing data unit.
The apparatus of claim 37, further comprising:

means for determining that a data unit status report was triggered after the expiration of a delivery timer; and

means for stopping the wait timer based at least in part on the determination.
A non-transitory computer-readable medium storing code for wireless communication at a radio interface protocol layer of a user equipment (UE) , the code comprising instructions executable by a processor to:

receive a subset of a series of data units from a first base station via a radio frequency (RF) chain according to a first subscription associated with a first subscriber identity module (SIM) of the UE;

start a reordering timer for the series of data units upon identifying at least one missing data unit in the received subset of the series of data units;

receive, from a physical layer, an indication that the RF chain is being used for communicating with a second base station according to a second subscription associated with a second SIM of the UE;

pause the reordering timer based at least in part on receiving the indication; and

deliver the subset of the series of data units to a higher layer based at least in part on the reordering timer.
The non-transitory computer-readable medium of claim 40, wherein the instructions are further executable to:

start a delivery timer upon receiving the indication when the at least one missing data unit is identified prior to receiving the indication or upon identifying the at least one missing data unit in the received subset of the series of data units when the at least one missing data unit is identified after receiving the indication.
The non-transitory computer-readable medium of claim 41, wherein the instructions are further executable to:

store the subset of the series of data units received from the first base station; and

deliver the stored subset of the series of data units in ascending order to the higher layer after the delivery timer expires.
The non-transitory computer-readable medium of claim 41, wherein the instructions are further executable to:

trigger a data unit status report after the delivery timer expires.
The non-transitory computer-readable medium of claim 41, wherein the instructions are further executable to:

store the subset of the series of data units received from the first base station;

receive the at least one missing data unit before the delivery timer expires;

deliver the stored subset of the series of data units in ascending order to the higher layer including the at least one missing data unit; and

reset the delivery timer and the reordering timer.
The non-transitory computer-readable medium of claim 40, wherein the reordering timer is started prior to receiving the indication, and wherein the reordering timer is paused upon receiving the indication.
The non-transitory computer-readable medium of claim 40, wherein the indication is received prior to identifying the at least one missing data unit, and wherein the reordering timer is started and paused upon identifying the at least one missing data unit.
The non-transitory computer-readable medium of claim 40, wherein the instructions are further executable to:

receive, from the physical layer, a second indication that the RF chain is switching from being used for communicating with the second base station according to the second subscription to being used for communicating with the first base station according to the first subscription.
The non-transitory computer-readable medium of claim 47, wherein the instructions are further executable to:

extend the reordering timer upon receiving the second indication; and

resume the reordering timer.
The non-transitory computer-readable medium of claim 48, wherein the instructions are further executable to:

revert the reordering timer to a configured value after the reordering timer expires.
The non-transitory computer-readable medium of claim 47, wherein the instructions are further executable to:

start a wait timer upon receiving the second indication.
The non-transitory computer-readable medium of claim 50, wherein the instructions are further executable to:

trigger a data unit status report after the wait timer expires when the radio interface protocol layer fails to receive the at least one missing data unit.
The non-transitory computer-readable medium of claim 50, wherein the instructions are further executable to:

determine that a data unit status report was triggered after the expiration of a delivery timer; and

stop the wait timer based at least in part on the determination.