Controlling post-transmission-grant active time based on likelihood of retransmission grant

Abstract

A method and system to control how long a user equipment device (UE) will monitor for retransmission grant reception after engaging m a scheduled uplink transmission to an access node serving the UE. An example method involves the UE monitoring an extent to which the UE receives retransmission grants from the access node before die scheduled uplink transmission, e.g., monitoring on a per-uplink-transmission-transaction basis over a sliding window of a number of connected-mode-discontinuous-reception (cDRX) cycles. Further, the example method involves the UE using the monitored extent to which the UE receives retransmission grants as a basis to control by the UE a quantity of retransmission-grant windows after the scheduled uplink transmission in each of which the UE will monitor for receipt of a respective retransmission grant from the access node (in addition to any such monitoring within configured cDRX on-duration-time (ODT) configured for the UE).

Description

Attorney Docket No.24-0613-WO Controlling Post-Transmission-Grant Active Time Based on Likelihood of Retransmission Grant BACKGROUND

[0001] A traditional cellular wireless communication system includes multiple access nodes configured to serve user equipment devices (UEs) such as cell phones, tracking devices, wirelessly equipped personal computers, gaming devices, media players, Internet of Things (IoT) devices, and other wirelessly-equipped devices, whether or not technically “user” operated.

[0002] Each access node may provide one or more cells each defining wireless coverage in which to serve UEs over a respective air-interface. Further, each access node may be coupled with a core network that includes infrastructure configured to support the access node’s service of UEs and that provides connectivity with a transport network such as the Internet. With this arrangement, when a UE is positioned within coverage of an access node, the UE may be able to engage in air-interface communication with the access node and may thereby be able to communicate through the access node, the core network, and the transport network with various remote servers and / or other entities.

[0003] A representative wireless communication system could operate in accordance with one or more radio access technologies (RATs), which may define the physical structure of the air interface between access nodes and UEs and may also define associated procedures for service of UEs.

[0004] Recent examples of these RATs include, without limitation, (i) “4G” Long Term Evolution (LTE), which facilitates mobile broadband service using technologies such as orthogonal frequency division multiplexing (OFDM) and multiple input multiple output (MIMO), (ii) “5G NR” (5G New Radio), which may use a more scalable OFDM air interface and other advanced features to support higher data rates and advanced applications, and (iii) “6G”, which might support even higher data rates, possibly by making use of millimeter wave and Terahertz spectrum.

[0005] Under such a RAT, the access node may be configured to provide each of its one or more cells on a respective radio frequency (RF) carrier that defines a downlink channel for carrying communications from the access node to UEs and an uplink channel for carrying communications from UEs to the access node. Each such carrier, and thus each such cell, may be either frequency division duplex (FDD), with separate frequency channels definedAttorney Docket No.24-0613-WO respectively for downlink and uplink use, or time division duplex (TDD), with a single frequency channel multiplexed over time between downlink and uplink use.

[0006] Further, the downlink and uplink channels of each cell on which an access node provides service may be structured in a manner that defines physical air-interface resources for carrying both control signaling and user-plane communications between the access node and UEs. For instance, the air interface may be divided over time into frames, subframes (e.g., 1 millisecond (ms) each), timeslots (slots), and symbol time segments (symbols), and over frequency into subcarriers, so as to define an array of resource elements each occupying a respective subcarrier and spanning a respective symbol time segment. Each resource element may then serve to carry data (user-plane or control-plane) through modulation of the resource element’s subcarrier with an applicable modulation-and-coding scheme. Further, the air interface may be divided over time and channel bandwidth into physical resource blocks (PRBs), each of which may span a certain number of subcarriers (e.g., 12) in frequency and a certain duration (e.g., half of a timeslot) in time. In addition, certain resource elements in these PRBs may be reserved for particular use, such as to carry control signaling or to carry user-plane data communications.

[0007] On the downlink, for instance, certain resource elements may cooperatively carry signaling from the access node that UEs could measure as a basis to gauge cell coverage strength. Further, other resource elements may cooperatively define a physical downlink control channel (PDCCH) for carrying downlink control signaling such as scheduling directives from the access node to UEs. Still further, other resource elements may cooperatively define a physical downlink shared channel (PDSCH), and the access node could schedule use of the PDSCH on a PRB basis for use to carry user-plane data from the access node to served UEs.

[0008] On the uplink, on the other hand, certain resource elements may cooperatively define an access channel for carrying access requests from UEs to the access node. Further, other resource elements may cooperatively define a physical uplink control channel (PUCCH) for carrying various uplink signaling such as measurement reports and scheduling requests from UEs to the access node. Still further, other resource elements may cooperatively define a physical uplink shared channel (PUSCH), and the access node could schedule use of the PUSCH on a per PRB basis to carry user-plane data from served UEs to the access node.Attorney Docket No.24-0613-WO SUMMARY

[0009] When a UE enters into coverage of such a system the UE may scan for and discover sufficiently strong coverage of an access node, and the UE may then engage in signaling with that access node to connect with the access node. For instance, the UE may engage in random-access signaling and Radio Resource Control (RRC) signaling with the access node to establish a logical RRC connection between the UE and the access node, thus transitioning the UE from an RRC idle mode to an RRC connected mode. Further, if the UE is not already registered with the core network, the UE may register with the core network through the UE’s established RRC connection.

[0010] Once the UE is RRC-connected, the UE may then engage in wireless packet- data communication, with the access node coordinating use of air-interface resources for carrying packet-data to and from the UE.

[0011] For instance, when the UE has data to transmit to an entity on the transport network, the UE may transmit a scheduling request (SR) to the access node on the PUCCH, and, in response, the access node may assign one or more uplink PRBs for use to carry at least some of the data over the air from the UE to the access node and may transmit to the UE on the PDCCH a Downlink Control Information (DCI) message that specifies the assigned uplink PRB(s). The UE may then receive and read this DCI message to determine the assigned uplink PRB(s), and the UE may accordingly transmit data over the air to the access node in the assigned uplink PRB(s). Upon receipt of this data transmitted by the UE, the access node may then forward the data through the core network for output onto the transport network and ultimate routing to the destination entity.

[0012] Further, when a remote entity transmits data on the transport network for receipt by the UE, that data may arrive at the UE’s registered core network and may flow through the core network to the UE’s serving access node. The access node may then assign one or more downlink PRBs for use to carry at least some of that data over the air from the access node to the UE, and the access node may transmit to the UE on the PDCCH a DCI message specifying the assigned downlink PRB(s) and may accordingly transmit data over the air to the UE in the assigned downlink PRB(s). The UE may thus receive and read the access node’s DCI message to determine the assigned downlink PRB(s) and may accordingly receive the transmitted data in the assigned downlink PRB(s).

[0013] For both downlink and uplink air-interface communication, the UE and access node may also apply a retransmission process when necessary to handle errors in theirAttorney Docket No.24-0613-WO air-interface transmissions. This process may occur on a per-transport-block basis, i.e., respectively for each block of data that the access node schedules to be transmitted, and the process may be a Hybrid Automatic Repeat Request (HARQ) process and may have a corresponding HARQ process identifier that the access node specifies in its DCI messaging to the UE.

[0014] With example HARQ as to scheduled downlink transmission of data, for instance, the UE could perform a cyclic redundancy check (CRC) to determine if the UE successfully received the data and could transmit to the access node either a positive acknowledgment (ACK) or a negative acknowledgement (NACK), with a NACK causing the access node to schedule and provide retransmission of the data to the UE, possibly with added error-correction information. Whereas, with example HARQ as to scheduled uplink transmission of data, the access node could perform a CRC of received data to determine if the access node successfully received the data and, if not, could transmit to the UE a DCI message that constitutes a retransmission-grant for the same HARQ process, directing the UE to retransmit at least a portion of the data to the access node possibly along with added error- correction information.

[0015] For both downlink and uplink, there may be a maximum number of allowed such transmission attempts per HARQ process, referred to as max-HARQ-Tx (also referred to as “maxHARQTx”) (possibly five or seven, for instance). If transmission is not successful after allowing for that maximum number of transmission attempts, then the transmission of that block of data may be deemed to have failed and may be abandoned.

[0016] When a UE is RRC connected, the UE may need to regularly monitor the PDCCH in search of DCI messages that the access node may send to the UE to schedule air- interface communication with the UE. This monitoring may involve the UE engaging in a “blind-decoding” process in which the UE evaluates various groups of resource elements on the PDCCH in search of any DCI message that is directed to the UE (e.g., a DCI message that is masked (e.g., scrambled) with an identifier (e.g., cell radio network temporary identifier (C- RNTI)) assigned to the UE). Accordingly, if the PDCCH is transmitted frequently, such as in every downlink subframe or timeslot, then the UE may need to perform this monitoring just as frequently.

[0017] Because this frequent monitoring of the PDCCH may drain the UE’s battery energy, the UE may instead operate with a process called connected-mode discontinuous reception (cDRX) to help reduce the amount of time that the UE’s radio and associatedAttorney Docket No.24-0613-WO processing logic is active. According to cDRX, the UE in the RRC connected mode may generally remain in a low-power inactive or sleep state (e.g., with its cellular modem powered down) in which the UE does not monitor the PDCCH for signaling from the access node, but the UE will periodically wake up and operate in an active state for just a cDRX on-duration time (ODT) to monitor for PDCCH signaling, after which the UE will then go back to sleep if possible.

[0018] In practice, the access node may configure the UE with cDRX timing parameters (e.g., cDRX timing parameters defined for the UE), though RRC configuration messaging when the UE first connects with the access node and / or at other times, possibly based on the type of communication in which the UE is engaged. Further, for scheduling downlink transmission to the UE, the access node may then be set to transmit any DCI messages to the UE just during the UE’s configured ODT instances, i.e., when the access node knows that the UE will be monitoring the PDCCH.

[0019] When a UE is operating with cDRX, in addition to the UE being active for each of the UE’S periodically recurring ODT instances, the UE may also be active at other times to the extent necessary to facilitate the UE’s air-interface communication with the access node.

[0020] An example of such other times may be if the UE starts an uplink- transmission transaction with the access node at some point between the UE’s ODT instances. When the UE is in the cDRX sleep state between ODT instances and the UE has data to transmit, for instance, the UE may respond to the existence of that data by engaging in an uplink-transmission transaction with the access node as noted above, namely, transmitting an SR to the access node, then searching for, receiving, and reading a DCI message from the access node that schedules use of uplink PRB(s) to carry data from the UE, and then transmitting the data in the scheduled uplink PRB(s). Further, this active time may be extended for HARQ processing. In any event, the start of this uplink-transmission transaction (e.g., when the UE sends the SR to the access node) may represent the UE transitioning from the cDRX sleep state to the cDRX active state. And as this occurs between the UE’s configured ODT instances in this example, the UE would therefore be active for at least some time other than the UE’s configured ODT instances.

[0021] Another example of such other times may be if the UE seeks to initiate uplink data communication during one of the UE’s ODT instances, and the uplink-transmission transaction process, including any HARQ processing, extends beyond the end of that ODTAttorney Docket No.24-0613-WO instance. For instance, during an ODT instance, if the UE has data to transmit, the UE may responsively engage in the above-noted uplink-transmission transaction with the access node. But at least part of that transaction may extend beyond the end of the ODT instance. In that case, the UE may remain active until the end of its uplink-transmission transaction, and thus beyond the end of the ODT instance.

[0022] Unfortunately, having a connected-mode UE be active at times other than its normal ODT instances is undesirable for at least the reason noted above. Namely, the more time the UE is active, the more the UE’s battery energy may be drained.

[0023] The present disclosure provides technical advances that may help to avoid or minimize this problem.

[0024] In one respect, the present disclosure provides a mechanism to help minimize an amount of time that a UE will remain in the cDRX active state after engaging in scheduled transmission of packet data to the UE’s serving access node, with the UE taking into account how many retransmissions of the packet data may be required. For instance, the UE may monitor how many retransmission grants the UE has tended to receive recently on a per uplink- transmission-transaction basis, and the UE may use the monitored number of transmission grants as a basis to configure how the long the UE will monitor for an retransmission grant as to a future data transmission. This process may thereby help avoid having the UE stay active for an unnecessarily long time after the UE’s initial transmission.

[0025] By way of example, disclosed is a method to control how long a UE will monitor for retransmission grant reception after engaging in a scheduled uplink transmission to an access node serving the UE. The method may involve the UE monitoring an extent to which the UE receives retransmission grants from the access node before the scheduled uplink transmission, e.g., an extent of retransmission grants on a per-uplink-transmission-transaction basis. Further, the method may involve the UE using the monitored extent to which the UE receives retransmission grants the monitored extent to which the UE receives retransmission grants as a basis to control a quantity of retransmission-grant windows after the scheduled uplink transmission in each of which the UE will monitor for receipt of a respective retransmission grant from the access node.

[0026] In another respect, the present disclosure provides for the UE engaging in processing to help correlate the UE’s uplink-transmission transaction with a cDRX ODT defined for the UE. This process may help control when the UE will start an uplink-transaction, such as when the UE will send an SR to the access node, in an effort to maximize timeAttorney Docket No.24-0613-WO alignment of the UE’s uplink-transmission transaction with an ODT instance configured for the UE.

[0027] By way of example, disclosed is a method to control SR transmission from a UE to an access node serving the UE. The method may involve the UE selecting an SR occasion (e.g., on the PUCCH) at which the UE will start a transmission process (e.g., an uplink- transmission transaction) for data to be transmitted over an air-interface from the UE to the access node, with the selecting being based on a determination that use of the selected SR occasion will help maximize overlap of active time of the UE for the transmission process with active time of the UE according to a cDRX configuration of the UE. Further, the method may involve, based on the selecting, the UE transmitting to the access node, in the selected SR occasion, a scheduling request requesting the access node to provide the UE with an uplink grant of air-interface resources to facilitate transmission of the data over the air-interface from the UE to the access node.

[0028] In some examples, the UE could achieve transmission of the SR in the selected SR occasion by controlling timing of internal delivery of the packet data to a Layer-2 (L2) buffer in the UE such that time of receipt of the packet data into the Layer-2 buffer results in the UE starting the transmission process at the selected SR occasion. For instance, the UE may process the data through an internal protocol stack from an application layer down to a Media Access Control (MAC) layer and then store the data in the L2 buffer at the MAC layer pending the transmission, and the controlling could occur at the application layer.

[0029] Further, disclosed is a UE configured to carry out one or more of these methods. For instance, the UE may include a wireless communication interface through which the UE engages in air-interface communication with a serving access node, and the UE may include one or more processors (e.g., a host processor and / or a baseband processor of the wireless communication interface), non-transitory data storage, and program instructions stored in the non-transitory data storage and executable by the processor to carry out the disclosed operations.

[0030] Still further, disclosed is a non-transitory computer-readable medium having stored thereon instructions executable by a processor to cause a UE to carry out the disclosed operations. And yet further, disclosed is a computer program comprising program instructions executable by a processor of a UE to carry out the disclosed operations, such as any one or more of the disclosed methods for instance.Attorney Docket No.24-0613-WO

[0031] These, as well as other aspects, advantages, and alternatives will become apparent to those of ordinary skill in the art by reading the following detailed description, with reference where appropriate to the accompanying drawings. Further, it should be understood that the descriptions provided in this summary and below are intended to illustrate the invention by way of example only and not by way of limitation. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a simplified block diagram of an example wireless communication system in which various disclosed features could be implemented.

[0033] Figure 2 is a simplified illustration of an example HARQ retransmission process.

[0034] Figure 3 (parts 3A and 3B) is a simplified illustration of an example Cdrx implementation

[0035] Figure 4 is a simplified illustration of how a UE may operate in a connected- mode active state in multiple retransmission-grant windows after a scheduled uplink transmission.

[0036] Figure 5 is a flow chart illustrating an example method.

[0037] Figure 6 is a simplified illustration of a protocol stack for processing outbound data.

[0038] Figure 7 is a simplified illustration of context for SR-occasion selection.

[0039] Figure 8 is a flow chart illustrating another example method.

[0040] Figure 9 is a simplified block diagram of an example UE. DETAILED DESCRIPTION

[0041] Referring to the drawings, as noted above, Figure 1 is a simplified block diagram of an example cellular wireless communication system in relation to which various disclosed features could be implemented.

[0042] In Figure 1, the example cellular wireless communication system includes a radio access network (RAN) 100 and a core network 102. The RAN 100 may include numerous access nodes configured to cooperatively provide coverage throughout a given market area. As shown, for instance, the RAN 100 may thus include an example access node 104, which may include an antenna structure and associated equipment (neither shown) configured to provide UEs with cellular service over an example air interface 106 defining a cell. The core networkAttorney Docket No.24-0613-WO 102 may then include a user-plane subsystem 108 for carrying user-plane communications (e.g., application-layer communications) to and from UEs, and a control-plane subsystem 110 for controlling registration and setup and management of service flows for UEs. In addition, the core network 102 is shown providing connectivity with an example transport network 112 such as the internet.

[0043] This cellular wireless communication system could operate in accordance with one or more RATs as noted above, which may define the physical structure of the air interface 106 including channels like those described above, and may also define associated procedures for handling service of UEs.

[0044] In line with the discussion above, when an example UE 114 is within sufficiently strong coverage of the access node 104, the UE may engage in random-access signaling and RRC signaling with the access node to establish an RRC connection between the access node and the UE in the cell, putting the UE into an RRC-connected mode. Further, if the UE is not already registered with the core network 102 to engage in cellular communication service, the UE may also engage in registration signaling with the control-plane subsystem 110, through non-access stratum (NAS) signaling via the access node, to register for service. For instance, the UE may send a registration request over its RRC connection to the access node, which the access node may forward into the control-plane subsystem 110 for processing. After authenticating the UE, the control-plane subsystem 110 may then engage in a process to set up for the UE one or more quality-of-service (QoS) flows (or bearers) for carrying user-plane traffic through the user-plane subsystem 108 to and from the UE.

[0045] As discussed above, once the UE is RRC-connected, the UE may then engage in wireless packet data communication (i.e., packet data communication via the UE’s air- interface connection) with various remote entities, such as with an example remote entity 116 as shown in Figure 1, with the access node coordinating the air-interface portion of the communication.

[0046] This packet-data communication may take various forms, possibly including real-time media communication such as voice, streaming media, and / or gaming communication, and / or non-real-time communication such as file transfer, message communication, or the like. The remote entity 116 may therefore also take various forms, such as an end-user device or an application server, possibly an Internet Multimedia Subsystem (IMS) platform, among other possibilities.Attorney Docket No.24-0613-WO

[0047] As to uplink communication in particular, when the UE has data to transmit, the UE may transmit an SR to the access node on the PUCCH, and the access node may assign PUSCH resources to carry the data from the UE and may transmit to the UE on the PDCCH a DCI message designating those assigned PUSCH resources. Through blind-decoding, the UE may thus discover this DCI message transmitted from the access node, and the UE may accordingly transmit the data to the UE on the assigned PUSCH resources.

[0048] Further, for uplink communications, the UE and access node may engage in a HARQ processing as noted above, to help deal with possible transmission errors. In practice, for instance, once the access node schedules PUSCH transmission from the UE for a given HARQ process, the access node may then determine if the access node successfully receives that scheduled PUSCH transmission from the UE, and if not, the access node may provide the UE with a retransmission grant. Namely, if the access node does not successfully receive the UE’s scheduled PUSCH transmission (e.g., by not receiving the transmission or by detecting through a CRC analysis that the transmission was in error), the access node may transmit to the UE on the PDCCH a DCI message for the same HARQ process, directing the UE to retransmit at least a portion of the data possibly together with some added error correction information, and the UE may accordingly engage in retransmission as scheduled. The access node may include in such a DCI message an indicator that is interpretable by the UE to mean that the DCI message is a retransmission grant rather than a transmission grant, so that the UE will treat the DCI message as a directive to retransmit the data for the same HARQ process.

[0049] For each uplink HARQ process, after the UE receives a first transmission grant from the access node, the UE may be configured to allow a particular amount of time in which the UE may receive one or more retransmission grants from the access node. If the maximum allowed number of transmissions per HARQ process is N = max-HARQ-Tx as noted above, and if each retransmission-grant window is defined as a Round Trip Time (RTT) to allow for the UE’s PUSCH transmission to the access node and the access node’s response to the UE with a DCI message defining a retransmission grant, then the total amount of time that the UE would need to allow for receipt of one or more retransmission grants would be (N- 1)(RTT). For instance, if N=5 and RTT=8ms, then there would be 4 retransmission-grant windows of duration 8ms each, so the UE would need to allow for 32ms after its receipt of the first transmission grant in which to receive one or more retransmission grants from the access node.Attorney Docket No.24-0613-WO

[0050] In practice, for each HARQ process, the UE may be configured to monitor the PDCCH for this entire allowed time after the UE receives a first transmission grant from the access node. Alternatively the UE may be configured to monitor the PDCCH just in a last portion of each retransmission-grant window, as a retransmission-timer period in which the UE might receive a retransmission grant from the access node. Further, for each of one or more retransmission grants that the UE receives from the access node during this allowed time after the UE’s receipt of the first transmission grant, the UE may responsively retransmit to the access node as scheduled.

[0051] Figure 2 illustrates this retransmission process by way of example for a given HARQ process, e.g., for uplink transmission of a given block of data from the UE to the access node. This example assumes that N = max-HARQ-Tx = 5, and so there are four retransmission- grant windows as discussed above.

[0052] As shown in Figure 2, at step 200, for the block of data at issue, the UE first sends an SR to the access node. At step 202, the UE then receives from the access node first uplink transmission grant, scheduling PUSCH transmission from the UE in designated upcoming PUSCH resources. At step 204, the UE then engages in PUSCH transmission as scheduled. At that point, the UE then monitors for retransmission grants from the access node in each of the four retransmission grant windows 206, each defined by an RTT period 208 and including a retransmission-timer period 210. Further after each retransmission-grant window in which the UE receives from the access node a retransmission-grant for the same HARQ process, the UE then responsively engages in the scheduled retransmission to the access node.

[0053] This retransmission process may differ depending on the RAT.

[0054] In LTE, for instance, once the access node transmits to the UE a first uplink transmission grant for a given HARQ process, if the access node receives that scheduled uplink transmission, then the access node may transmit to the UE an ACK control message that indicates that the access node received the transmission, but the access node may then still engage in CRC processing and transmitting of one or more retransmission grants to the UE in the one or more allowed retransmission-grant windows. Therefore, in LTE, once the UE receives an ACK for its uplink transmission, the UE may then monitor for retransmission grants in the number of allowed retransmission-grant windows after the first transmission grant, and for each retransmission grant may retransmit accordingly.

[0055] Whereas, in NR, uplink HARQ is asynchronous, without any ACK signaling from the access node to the UE. Rather, once the access node transmits to the UE a first uplinkAttorney Docket No.24-0613-WO transmission grant for a given HARQ process, the access node may engage in CRC processing and transmitting of one or more retransmission grants to the UE in the one or more allowed retransmission-grant windows. Thus, in NR, once the UE receives a first transmission grant and engages in the scheduled uplink transmission, the UE may then monitor for retransmission grants in the number of allowed retransmission grant windows after the first transmission grant, and for each retransmission grant may retransmit accordingly.

[0056] As further noted above, when the UE is RRC connected, the UE may operate with cDRX.

[0057] Figures 3A and 3B illustrate example cDRX implementation. As shown in Figure 3A, cDRX defines a cDRX cycle 300 and an ODT 302 that periodically recurs at least once per cDRX cycle. With this arrangement, in each cDRX cycle 300, the UE may operate in a DRX sleep state for a DRX OFF period in which the UE’s modem may be powered off or in a reduced power mode and the UE does not monitor the PDCCH, and the UE may operate in a DRX active state for a DRX ON (ODT) period 302 in which the UE’s modem may be powered on and the UE would monitor the PDCCH. Further, as shown in Figure 3B, cDRX also defines an inactivity timer (IAT) 304 that restarts each time the UE receives a DCI message scheduling downlink or uplink transmission, and the UE would remain active until at least the expiration of that inactivity timer even if the inactivity timer expires beyond the end of an ODT 302.

[0058] In practice, cDRX may further define parameters to facilitate the above- described HARQ processing, namely, to help ensure that the UE is active when the UE needs to be active in order to monitor for retransmission grants from the access node. For this purpose, cDRX may define max-HARQ-Tx, RTT, as well as a retransmission-timer period at the end of each retransmission-grant window.

[0059] As noted above, the access node may configure the UE with various cDRX parameter values, through RRC signaling with the UE. For instance, the access node may configure values of the cDRX cycle, the ODT period (onDurationTimer), the inactivity timer period (drx-InactivityTimer), max-HARQ-Tx, and the retransmission-timer period (drx- RetransmissionTimer). Further, the RTT parameter may be set to a default value depending on whether the carrier in use is FDD or rather TDD.

[0060] As further noted above, the present disclosure provides mechanisms to help minimize the extent to which the connected-mode UE will be active at times other than the UE’s configured cDRX ODT periods. The following subsections will describe example mechanisms, which could be applied separately or in combination with each other.Attorney Docket No.24-0613-WO Controlling Post-Transmission-Grant Active Time Based on Likelihood of Retransmission Grant

[0061] As indicated above, one mechanism provides for controlling how long a UE will monitor for retransmission grants and thus how much time the UE will need to be active to engage in that monitoring. In particular, this mechanism may involve controlling how many retransmission-grant windows the UE will be set to monitor, based on the UE’s recent history of receipt of retransmission grants.

[0062] The technical issue here is that, with the HARQ process described above, the UE would monitor for the N = max-HARQ-Tx number of retransmission grants after the UE’s initial transmission and would therefore need to be in the active state to engage in that monitoring. In some implementations, this may mean that the UE would remain in the active state for the full duration of (N-1)(RTT), i.e., for the full duration of all N-1 retransmission- grant windows, after the UE receives the first transmission grant for a given HARQ process, to allow the UE to monitor for the N-1 retransmission grants. In other implementations, this may mean that the UE would need to be in the active state for at least the retransmission-timer period of each of the N-1 retransmission-grant windows. In any event, this active time would most likely encompass at least some time between the UE’s configured cDRX ODT instances, which would be undesirable as noted above.

[0063] Figure 4 illustrates this issue by way of example, though not to scale. This example assumes that (i) N = max-HARQ-Tx = 5, (ii) RTT=8ms, (iii) cDRX cycle = 60ms, (iv) ODT = 4ms, and (v) inactivity timer = 4ms. This example also assumes that the UE has data in its L2 buffer at a time that causes the UE to send an SR to the access node in an SR occasion shortly before one of the UE’s ODT instances.

[0064] As shown in Figure 4, after the UE sends the SR to the access node as the start of an uplink-transmission transaction, the UE would then monitor for a first transmission grant for a HARQ process and, upon receipt of the first transmission grant, would then engage in PUSCH transmission as scheduled. In turn the UE would then monitor for a retransmission grant respectively in each of the (N-1) = 4 retransmission-grant windows starting from the UE’s receipt of the first transmission grant. Thus, the UE may be active for the full duration of (N- 1)(RTT) = 32ms after the UE receives the first transmission grant, or at least for the retransmission-timer period of each of the (N-1) = 4 retransmission-grant windows. Unfortunately, however, much of this active time would occur outside of the UE’s ODT instances and may therefore undesirably consume more of the UE’s battery energy.Attorney Docket No.24-0613-WO

[0065] Per the present disclosure, the UE can work to minimize the amount of time that the UE would monitor for retransmission grants, by taking into account the extent to which the UE has recently received retransmission grants on a per-HARQ-process basis.

[0066] A theory here is that the extent to which the UE has recently received retransmission grants may correlate with quality of the UE’s uplink air-interface connection with the access node or one or more other associated metrics. If the UE is in relatively good quality coverage of the access node, then the UE may receive few if any retransmission grants from the access node on a per-HARQ-process basis; conversely, if the has received few if any retransmission grants from the access node on a per-HARQ-process basis, that may mean that the UE is in relatively good coverage of the access node with little risk of errors in uplink transmission, and there may therefore be relatively low likelihood of the UE needing to retransmit. Whereas, if the UE is in relatively poor quality coverage of the access node, then the UE may receive more retransmission grants from the access node on a per-HARQ-process basis; conversely, if the UE has received many retransmission grants from the access node on a per-HARQ-process basis, that may mean that the UE is in relatively poor coverage of the access node with more of a risk of errors in uplink transmission, and there may therefore be relatively high likelihood of the UE needing to retransmit.

[0067] Accordingly, the UE may monitor the extent to which the UE receives retransmission grants from the access node on a per-uplink-transmission-transaction basis (e.g., per-HARQ-process basis). The UE may conduct this monitoring on a sliding window over at least a recent predefined period of time while the UE is served by the access node. This predefined period of time could be set to a duration that is deemed to reasonably represent how many retransmission grants the UE has recently tended to receive from the access node, and thus to support a prediction of how many retransmission grants the UE is likely to receive on a per-uplink-transmission-transaction basis. For instance, the period could be set to a number of cDRX cycles such as four to eight cDRX cycles, among other possibilities. In this monitoring, the UE may keep a rolling average or other statistical representation of the number of retransmission grants that the UE has received on a per-uplink-transmission-transaction basis, as an example representation of the extent to which the UE receives retransmission grants.

[0068] The UE may then use this monitored extent to which it receives retransmission grants as a basis to control how long the UE will monitor for retransmissionAttorney Docket No.24-0613-WO grants moving forward. In practice, this may involve the UE dynamically setting its configured value of max-HARQ-Tx, possibly to a value lower than that configured by the access node.

[0069] In an example implementation, the UE may initially apply the max-HARQ- Tx value configured by the access node, or another default max-HARQ-Tx value. Thus, if the value of max-HARQ-Tx is 5, the UE may initially be set to monitor for retransmission grants in (N-1) = 4 retransmission-grant windows after the UE receives the first transmission grant for a HARQ process.

[0070] While applying this default value of max-HARQ-Tx over a sliding window monitoring period, such as over a predefined number of cDRX cycles as noted above, the UE could determine how many retransmission grants the UE has been receiving on a per-uplink- transmission-transaction basis, as a prediction of how many of how many retransmission grants the UE will receive on a per-uplink-transmission-transaction basis. Based on that determination, the UE may then control what value of max-HARQ-Tx the UE will use moving forward.

[0071] By way of example, the UE may determine whether the UE received any retransmission grants in a most recent monitoring window (e.g., within the most recent past predefined number of cDRX cycles). In this example, if the UE has received any retransmission grants in the monitoring window, then the UE may responsively apply a first (e.g., default) value of max-HARQ-Tx (e.g., as configured by the access node) moving forward. Whereas, if the UE has not received any retransmission grants in the monitoring window, then the UE may apply a second value, M, of max-HARQ-Tx that is less than the first value of max-HARQ-Tx. The lesser value M may be configurable and could be set to 1 for instance or possibly 2 to cause UE to monitor in one retransmission-grant window.

[0072] This example could alternatively involve the UE evaluating a rolling average number of retransmission grants that the UE received over the course of the sliding monitored window and comparing that rolling average with a predefined low threshold value (e.g., 1, among other possibilities) as a basis to control whether to apply the first value of max-HARQ- Tx or rather a second, lower value of max-HARQ-Tx. For instance, if the UE determines that the rolling average is at least 1, then the UE may responsively apply the first value of max- HARQ-Tx value moving forward. Whereas, if the UE determines that the rolling average is less than 1, then the UE may responsively apply the second value of max-HARQ-Tx.

[0073] As another example, the UE may more directly base max-HARQ-Tx on the number of retransmission grants that the UE has tended to receive on a per-uplink-Attorney Docket No.24-0613-WO transmission-transaction basis or has received in the most recent monitoring window (e.g., predefined number of cDRX cycles). For instance, if UE received no retransmission grants in the most recent monitoring window, then the UE may set max-HARQ-Tx to 1 moving forward, so that the UE will not monitor for a retransmission grant after the UE’s first PUSCH transmission for a HARQ process. Whereas, if the UE received 1 retransmission grant in the most recent monitoring window, then the UE may set max-HARQ-Tx to 2 moving forward, so that the UE will monitor for a retransmission grant in a single retransmission-grant window. Further, if the UE received 2 retransmission grants in the most recent monitoring window, then the UE may set max-HARQ-Tx to 3 moving forward, so that the UE will monitor for a retransmission grant in 2 retransmission-grant windows. And if the UE received if the UE received 3 retransmission grants in the most recent monitoring window, then the UE may set max-HARQ-Tx to 4 moving forward, so that the UE will monitor for a retransmission grant in 3 retransmission-grant windows, and so forth.

[0074] In practice, if and when the UE thereby sets max-HARQ-Tx to a value that is less than the default max-HARQ-Tx value, the UE may apply an additional process to determine whether and when to revert to applying the default max-HARQ-Tx value (or perhaps otherwise increasing the max-HARQ-Tx value from the reduced value that the UE is applying). This additional process may involve the UE determining whether the UE receives a retransmission grant when the UE is active and thus monitoring for retransmission grants, such as during a cDRX ODT configured for the UE.

[0075] As an example of this additional process, assume that the UE has applied the above process and has thereby set max-HARQ-Tx to 1 so that the UE is set to not monitor for retransmission grants in any of the retransmission-grant windows. With the UE’s normal cDRX process, the UE would still be monitoring the PDCCH for DCI messages in each of the UE’s configured ODT instances. If, through that monitoring, the UE receives a retransmission grant, that would indicate that something went wrong with a PUSCH transmission from the UE. In response to receiving that retransmission grant, the UE may therefore revert to applying the default value of max-HARQ-Tx moving forward. In alternative implementations, the UE may base this reversion on the UE receiving at least two or more such retransmission grants, among other possibilities.

[0076] In these or other examples, particularly but not necessarily limited to a scenario where the UE does not even receive an ACK confirming that the access node received the UE’s PUSCH transmission (e.g., with 5G NR), the UE could also condition application ofAttorney Docket No.24-0613-WO this process on the UE determining that the UE is in good enough coverage of the access node (e.g., having good enough uplink air-interface quality) to justify applying a value of max- HARQ-Tx that is lower than the default value possibly configured by the access node.

[0077] For instance, in a scenario where the UE and access node engage in uplink power control to control the UE’s transmission, and where the UE has a power headroom value representing how much more the UE can increase its transmission power before reaching a maximum allowed transmission power level, the UE may base this on the UE’s currently set transmission power and / or the UE’s power headroom. If the UE’s currently set transmission power is lower than a predefined threshold level and / or the UE’s power headroom is higher than a predefined threshold level, then the UE may responsively engage in this process of dynamically controlling max-HARQ-Tx and particularly allowing max-HARQ-Tx to be lower than a default value. Whereas, if the UE’s currently set transmission power not lower than a predefined threshold level and / or the UE’s power headroom is not higher than a predefined threshold level, then the UE may responsively forgo engaging in this process. The UE may also consider other metrics for this purpose, including for instance downlink receive signal strength (e.g., reference signal receive power), as a possible surrogate for evaluating uplink quality.

[0078] Figure 5 is a flow chart illustrating an example method that a UE could carry out accordingly, to control how long the UE will monitor for retransmission grant reception after engaging in a scheduled uplink transmission to an access node serving the UE. As shown in Figure 5, at block 500, the example method includes the UE monitoring an extent to which the UE receives retransmission grants from the access node before the scheduled uplink transmission. At block 502 (which is shown subsequent to block 500 but may occur as a process in parallel with block 500), the UE uses the monitored extent to which the UE receives retransmission grants as a basis to control a quantity of retransmission-grant windows after the scheduled uplink transmission in each of which the UE will monitor for receipt of a respective retransmission grant from the access node.

[0079] In line with the discussion above, the quantity in this method could be (N-1), where N = max-HARQ-Tx, in which case the act of controlling the quantity could involve controlling a value of max-HARQ-Tx. For instance, the UE could have a default value of max- HARQ-Tx configured by the access node, and the act of controlling the quantity of retransmission-grant windows after the scheduled uplink transmission in each of which the UE will monitor for receipt of a respective retransmission grant from the access node could involve reducing the configured value of max-HARQ-Tx to a value lower than the default value.Attorney Docket No.24-0613-WO Further, as noted above, the act of reducing of the configured value of max-HARQ-Tx to the value lower than the default value could be based at least on (e.g., conditioned on) a determination by the UE that the UE has at least threshold high uplink air-interface quality.

[0080] As additionally discussed above, the act of monitoring the extent to which the UE receives retransmission grants from the access node before the scheduled uplink transmission could be performed on a per-uplink-transmission-transaction basis (e.g., on a per HARQ-process basis) and could be performed over a sliding window defined as a multiple of cDRX cycles configured for the UE.

[0081] Further, as discussed above, the quantity of retransmission-grant windows after the scheduled uplink transmission in each of which the UE will monitor for receipt of a respective retransmission grant from the access node could be in addition to any cDRX on- duration-time in which the UE will monitor for scheduling directives (e.g., any uplink grants) from the access node. Namely, in addition to monitoring for a retransmission grant in each retransmission-grant window of the quantity, the UE may also have cDRX ODTs in which the UE engages in monitoring for scheduling directives, and some of those cDRX ODTs may overlap in time at least in part with one or more retransmission-grant windows of the quantity. Thus, the UE may monitor for retransmission grant reception from the access node within at least one cDRX on-duration time separate from the quantity of retransmission-grant windows.

[0082] Yet further, as discussed above, the act of the UE using the monitored extent to which the UE receives retransmission grants as a basis to control the quantity of retransmission-grant windows after the scheduled uplink transmission in each of which the UE will monitor for receipt of a respective retransmission grant from the access node could take various forms.

[0083] For instance, (i) the UE may make a determination of whether the monitored extent satisfies a predefined low threshold level, (ii) if the determination is negative, then, based at least on the determination, the UE may operate with the quantity set to a first quantity, and (iii) if the determination is affirmative, then, based at least on the determination, the UE may operate with the quantity set to a second quantity less than the first quantity. By way of example, the predefined low threshold level could be zero, the first quantity could be non-zero, and the second quantity could be zero.

[0084] As further discussed above, if the determination is affirmative and the UE therefore operates with the quantity set to the second quantity less than the first quantity, the UE could then engage in additional processing including (a) detecting receipt by the UE of aAttorney Docket No.24-0613-WO given retransmission grant, through monitoring by the UE during a cDRX ODT after passing of the second quantity of retransmission-grant windows and (b) responsive to at least the detecting, the UE switching to operate with the quantity set to the first quantity rather than the second quantity, or the UE otherwise increasing the quantity.

[0085] Still further, as discussed above the act of the UE using the monitored extent to which the UE receives retransmission grants as a basis to control by the UE the quantity of retransmission-grant windows after the scheduled uplink transmission in each of which the UE will monitor for receipt of a respective retransmission grant from the access node could involve based at least on the monitored extent, the UE operating with the quantity set to the monitored extent. Controlling Timing of Scheduling-Request Transmission Based on cDRX Timing

[0086] As indicated above, another mechanism provides for controlling when the UE will begin an uplink-transmission transaction in an effort to maximize alignment of the UE’s associated active time with the UE’s configured cDRX active time.

[0087] The technical issue here may arise as a result of SR occasions being defined for the UE separate from configuration of the UE’s cDRX timing. In practice, as noted above, the access node may configure the UE with cDRX parameters, such as periodicity of the UE’s ODT instances. Separately, but also through RRC signaling, the access node may also configure the UE with definitions of SR occasions available for use by the UE, such as by defining the SR occasions as occupying particular subcarriers in frequency and as occurring with particular periodicity and timing offset.

[0088] While the details of these settings are matters of design choice, it may well be the case that some of the UE’s defined SR occasions end up being relatively inefficiently positioned in time in relation to the UE’s ODT instances, while other of the UE’s SR occasions may end up being more efficiently positioned in time in relation to the UE’s ODT instances.

[0089] The efficiency of time placement of an SR occasion in relation to the UE’s ODT instances may be measured in relation to how well an uplink-transmission transaction starting at the SR occasion would align in time with the UE’s ODT instances. If the UE would be active for the duration of the uplink-transmission transaction stating with the UE’s transmission of an SR to the access node (possibly with some exception), it would be technically efficient to have that active time overlap as much as possible with one or more of the UE’s configured ODT instances, when the UE would be active anyway. Whereas, it wouldAttorney Docket No.24-0613-WO be less technically efficient to have that active time occur in between the UE’s configured ODT instances when the UE would not otherwise be active.

[0090] When the UE has data to transmit, it may therefore be useful to have the UE send an SR in an SR occasion that could help to align the UE’s uplink-transmission transaction for that data as much as possible with one or more of the UE’s configured ODT instances.

[0091] In normal practice, the UE may be configured to select the soonest upcoming SR occasion to use when the UE has data that is ready to be transmitted. More particularly, the UE may implement a protocol stack for processing outbound data, and the UE may select a soonest upcoming SR occasion to use once the UE has data in an L2 buffer ready to be transmitted.

[0092] Figure 6 illustrates an example of such a protocol stack, which extends from an application layer 600 down to a MAC layer 602 and the physical (air-interface) layer 604. The UE may be configured to engage in particular processing respectively at each of these layers. By way of example, at the application layer 600, the UE may establish data to be transmitted, at various intervening layers (e.g., Real-time Transport Protocol (RTP), Transport, Network, Packet Data Convergence Protocol (PDCP)), the UE may then operate on that data (e.g., segmenting the data, adding headers, etc.), and at the MAC layer 602, the UE may then hold the processed data in an L2 buffer 606 pending uplink scheduling and transmission.

[0093] The arrival of data in the L2 buffer 606 of the UE may be a trigger for UE, at the MAC layer, then proceeding to select an SR occasion in which the UE will transmit an SR to the access node as a request for an uplink transmission grant. In particular, at this point, the UE may then select a soonest upcoming SR occasion in which to transmit an SR to the access node, in order to start an uplink-transmission-transaction as soon as possible.

[0094] As presently contemplated, when the UE has data in its L2 buffer, instead of proceeding by rote to send an associated SR in a soonest upcoming SR occasion, the UE will send an SR in an SR occasion selected to help maximize timing overlap of the UE’s active time for the uplink-transmission transaction with the UE’s already configured cDRX active time.

[0095] To facilitate this, once the UE is initially configured by the access node with cDRX settings and with SR-occasion settings, the UE can engage in a self-configuration process to identify one or more “sync” points as SR occasions that would help align the UE’s active timing of uplink-transmission-transactions with the UE’s cDRX active time (e.g., ODT instances). The UE could then select one of these SR occasions when the UE has data in its L2 buffer 606 to be transmitted.Attorney Docket No.24-0613-WO

[0096] The process of the UE selecting each of these SR occasions may take various forms.

[0097] Without limitation, for instance, the UE may select an SR occasion based on the SR occasion being in close time proximity to the start of one of the UE’s configured ODT instances, such as within 1 to 2 ms of the start of the ODT instance, among other possibilities. Selecting an SR occasion that is in close time proximity to the start of an ODT instance may help align the UE’s active times as desired if the UE’s active time to monitor for an uplink transmission grant would then start early in the ODT instance (e.g., 1 to 2 ms into the ODT instance, among other possibilities) when the UE would be active anyway.

[0098] The UE’s selection of an SR occasion may be by way of comparison between SR occasions. For instance, the UE may select an SR occasion based on the selected SR occasion being in close time proximity to the start of an ODT instance, rather than selecting another SR occasion that is in close proximity to the end of an ODT instance, or rather than selecting an SR occasion that is very much between ODT instances and may result in threshold little or no time overlap between the UE’s active time for the uplink-transmission transaction and the UE’s configured cDRX active time. Thus, for instance, the may select an SR occasion to use based on the SR occasion being close in proximity to the start of an ODT configured for the UE and based on the SR occasion not being close in proximity to the end of an ODT defined for the UE (in both cases with proximity being defined as desired, such as but not limited to 1 to 2 ms for instance).

[0099] Figure 7 illustrates an example of this selection process. As shown, when data arrives at the UE’s MAC layer 602 and thus the L2 buffer 606, the UE could theoretically transmit an SR in a soonest upcoming SR occasion 700. However, as shown, that soonest upcoming SR occasion occurs just after one of the UE’s ODT instances, which is technically inefficient for the reasons noted above. Instead, to help maximize active time overlap as presently contemplated, the UE may wait and transmit an SR in a later upcoming SR occasion 702, based on the later upcoming SR occasion 702 occurring just before one of the UE’s ODT instances, which can help maximize active time overlap.

[0100] How well this process works in practice will of course depend on the UE’s specific cDRX and SR configuration parameters and other factors, such as the UE’s current setting of max-HARQ-Tx, and also how often the UE ends up with data in its L2 buffer 606 for transmission.Attorney Docket No.24-0613-WO

[0101] In an example implementation, this process of selecting and using an SR occasion that will help maximize active time overlap could be combined with the above- described process to dynamically set max-HARQ-Tx. For instance, if, through the above process, the UE can reduce its max-HARQ-Tx value to 1, so that the UE would go to sleep upon expiration of the inactivity time after its first PUSCH transmission for a HARQ process and would not monitor for retransmission grants, the UE’s associated active time would be shorter and it may therefore be easier for the UE to align that active time with a given one of the UE’s ODT instances by selecting and using a suitable SR occasion.

[0102] In practice, the UE could control this process at the MAC layer 602, responding to the presence of data in the L2 buffer 606 by sending an SR in an SR occasion that the UE selects (in advance or on the fly) to help maximize the UE’s active time overlap. Alternatively, the UE could control this process at a higher layer of the protocol stack, such as at the application layer 600 for instance, by controlling when data gets sent down the protocol stack to arrive at the L2 buffer 606.

[0103] By way of example, as the UE establishes data at the application layer 600 for the UE to transmit, the UE could control timing of output of that data at the application layer 600 for processing down the UE’s protocol stack so as to help cause the data to arrive at the L2 buffer 504 just before an SR occasion that would help maximize active time overlap.

[0104] To facilitate this, the UE could be provisioned, possibly self-configured, with (i) an indication of about how long it takes to process data down the UE’s protocol stack from the application layer 600 to the MAC layer 602 and (ii) sync points in time that would be at or just before SR occasions that could help maximize active time overlap. For instance, the UE may pre-select these SR occasions and store the sync points. (E.g., a baseband processor of the UE’s modem may preselect these SR occasions and store the sync points in data storage accessible to the application layer of the UE.) Based on this information, then, when the UE has data at the application layer for the UE to transmit, the UE could then hold that data at the application layer until a time of release down the stack that would result in arrival of the data at the L2 buffer 606 at or reasonably close in time (e.g., within 1 to 2 ms) of a defined sync point so as to cause the UE to then send an SR in an SR occasion that will help maximize active time overlap.

[0105] To additionally help in maximizing the extent to which the UE’s active time for uplink-transmission transactions will align with the UE’s configured cDRX ODT instances the UE may also bundle data when appropriate at the application layer, to reduce the numberAttorney Docket No.24-0613-WO of times the application layer sends data down the protocol stack for transmission – and thus the number of times data arrives at the L2 buffer 606 and triggers SR transmission. This enhancement may apply especially with, but not limited to, a scenario where the UE is engaged in a real-time packet-based media communication such as a voice-over-Internet-Protocol (VoIP) call or other real-time media communication where the UE may be transmitting a continuous stream of data.

[0106] With VoIP, for instance, if the UE is transmitting digitized voice to a remote device, the UE may generate at the application layer 600 a new voice packet every 20ms. Without the present arrangement, the UE may therefore pass down its protocol stack to its L2 buffer a new voice packet every 20ms, and so the UE may send a new SR to the access node every 20ms, which may mean that the UE may engage in a new uplink-transmission transaction every 20ms. To help reduce the frequency of such uplink-transmission transactions and their associated active times, the UE as presently contemplated could bundle voice packets. For example, the UE could concatenate every two 20ms voice packets, to establish a 40ms voice packet and could send each 40ms voice packet in turn down the protocol stack, each at an opportune time as noted above, for processing and transmission.

[0107] By combining together this packet bundling with the use of an SR occasion that helps to maximize active time overlap, and perhaps further with the dynamic configuration of max-HARQ-Tx, the UE can even further help minimize the amount of time that the UE would be active outside of the UE’s configured cDRX ODT instances. Further, other combinations of these and other procedures may be possible as well. Without limitation, for instance, the UE may combine together the packet bundling with the dynamic configuration of max-HARQ-Tx without also using an SR occasion selected to help maximize active time overlap.

[0108] Figure 8 is a flow chart illustrating an example method that a UE could carry out accordingly, to control SR transmission from a UE to an access node serving the UE. As shown in Figure 7, at block 800, the example method includes the UE selecting an SR occasion at which the UE will start a transmission process for data to be transmitted over an air-interface from the UE to the access node, with the selecting being based on a determination that use of the selected SR occasion will help maximize overlap of active time of the UE for the transmission process with active time of the UE according to a cDRX configuration of the UE. Further, at block 802, the method includes, based on the selecting, the UE transmitting to the access node, in the selected SR occasion, a scheduling request requesting the access node toAttorney Docket No.24-0613-WO provide the UE with an uplink grant of air-interface resources to facilitate transmission of the data over the air-interface from the UE to the access node.

[0109] In line with the discussion above, the UE could be configured with a plurality of SR occasions over time (e.g., per RRC configuration messaging from the access node), in which case, the act of the UE selecting the SR occasion could involve the UE selecting the SR occasion from the plurality of SR occasions. In practice, for instance, the UE may establish a set of the configured SR occasions by analyzing timing of the SR occasions in relation to timing of the UE’s cDRX ODTs, with the set of configured SR occasions being SR occasions that will help maximize the active time overlap as noted above. The UE could then select the SR occasion from that established set.

[0110] In an example implementation, as discussed above, the UE’s selecting of the SR occasion could occur when the UE has data in a Layer-2 buffer of the UE ready to be transmitted. In practice, for instance, the UE may process the data through an internal protocol stack from an application layer down to a MAC layer and then store the data in a buffer at the MAC layer pending the transmission, and the UE could then select the SR occasion. Further, as noted above, the selected SR occasion may not be a soonest upcoming SR occasion after the UE stores the data in the buffer. (E.g., the soonest upcoming SR occasion may be relatively undesirable, as starting the transmission process at that point may result in little if any timing overlap between the UE’s active time for the transmission process and the UE’s active time according to its cDRX configuration.)

[0111] As discussed above, the selecting of the SR occasion could be based at least in part on the SR occasion being in close time proximity to a start of a cDRX ODT configured for the UE. Further, the selecting of the SR occasion could be based at least on the SR occasion not being proximate in time to an end of a cDRX ODT defined for the UE.

[0112] As further discussed above, the act of the UE transmitting the SR in the selected SR occasion could involve the UE controlling timing of internal delivery of the packet data to a Layer-2 buffer in the UE such that time of receipt of the packet data into the Layer-2 buffer results in the UE starting the transmission process at the selected SR occasion. For instance, the UE may process the data through an internal protocol stack from an application layer down to a MAC layer and then store the data in the Layer-2 buffer at the MAC layer pending the transmission, and the controlling could occur at the application layer.

[0113] Still further, as discussed above, the data could comprise real-time media such as digitized voice, video, or other such media for instance, and the UE could bundlingAttorney Docket No.24-0613-WO sequential segments of the real-time media to form the data (e.g., at the application layer), with the bundling helping to reduce instances of uplink transmission and associated active time of the UE. Example Device Configuration

[0114] Figure 9 is a simplified block diagram of an example UE, showing some of the components that the example UE may include. As shown, the UE may include a wireless communication interface 900, a host processor 902, and non-transitory data storage 904. These components could be integrated together and / or communicatively linked together in various ways. For instance, the components could be linked together through a system bus, network, or other connection mechanism 906 and / or could be integrated together in various ways.

[0115] The wireless communication interface 900, which could be provided on a dedicated chipset among other possibilities, could include components that enable the UE to engage in air-interface communication with an access node through an antenna structure 908 of the UE. To facilitate this, the wireless communication interface 900 could include a baseband processor 910 and non-transitory data storage 912. The baseband processor 910 could one or more general purpose processors (e.g., one or more microprocessors, etc.) and / or one or more special-purpose processors (e.g., digital signal processors, application-specific integrated circuits, etc.). And the non-transitory data storage 912 could comprise one or more volatile and / or non-volatile storage components (e.g., optical, magnetic, or flash storage, RAM, ROM, EPROM, EEPROM, cache memory, and / or other computer-readable media, etc.), possibly integrated in whole or in part with the baseband processor 910. The non-transitory data storage 912 of the wireless communication interface 900 could hold program instructions 914 that may be executable by the baseband processor 910 to carry out various radio operations (e.g., modulation and demodulation) as well as various other operations described herein. Further, the wireless communication interface 900 could include a RF front end (RFFE) 916 including amplifiers and possibly other circuitry, to interface between the baseband processor 910 and the antenna structure 908.

[0116] The host processor 902 of the example UE could likewise comprise one or more general purpose processors and / or one or more special-purpose processors. And the non- transitory data storage 904 could likewise comprise one or more volatile and / or non-volatile storage components, possibly integrated in whole or in part with the processor 902. Further, the non-transitory data storage 904 may store program instructions 918 that may be executable by the host processor 902 to carry out various operations described herein.Attorney Docket No.24-0613-WO

[0117] With this arrangement, some operations of the UE could be carried out by the wireless communication interface 900, while other operations of the UE could be carried out by the host processor 902. For instance, the baseband processor 910 of the wireless communication interface 900 might handle setting of the max-HARQ-Tx value as discussed above and identifying candidate SR occasions that can help maximize timing overlap of the UE’s active time as discussed above. Whereas, the host processor 902 might handle application-layer control of bundling real-time data and / or control of when to output data down the UE’s protocol stack in an effort to cause use of an SR occasion that will help maximize the UE’s active time overlap as discussed above. Other implementations are possible as well.

[0118] As further shown, the example UE also includes a battery 920, which may provide energy to drive operation of various components of the UE. In line with the discussion above, various disclosed methods may help to minimize the amount of time that the UE is active when in an RRC-connected mode, which may thereby help to minimize drain of the UE’s battery energy.

[0119] In addition, the present disclosure also contemplates non-transitory data storage (e.g., one or more non-transitory computer-readable medium components (e.g., optical, magnetic, or flash storage, RAM, ROM, EPROM, EEPROM, etc.)) holding program instructions executable by at least one processor of a UE to cause the UE to carry out various operations described herein.

[0120] Further, the present disclosure also contemplates a computer program comprising a set of program instructions executable by at least one processor of a UE to carry out (e.g., to cause the UE to carry out) various operations described herein, such as to perform the various operations of the example methods and variations discussed above. In an example implementation, the computer program could further be stored in non-transitory data storage such as that noted above, among other possibilities.

[0121] Example embodiments have been described above. Those skilled in the art will understand, however, that changes and modifications may be made to these embodiments without departing from the true scope and spirit of the invention.

Claims

Attorney Docket No.24-0613-WO CLAIMS What is claimed is:

1. A method to control how long a user equipment device (UE) will monitor for retransmission grant reception after engaging in a scheduled uplink transmission to an access node serving the UE, the method comprising: monitoring by the UE an extent to which the UE receives retransmission grants from the access node before the scheduled uplink transmission; and using by the UE the monitored extent to which the UE receives retransmission grants as a basis to control by the UE a quantity of retransmission-grant windows after the scheduled uplink transmission in each of which the UE will monitor for receipt of a respective retransmission grant from the access node.

2. The method of claim 1, wherein the quantity is N-1, wherein N = max-HARQ-Tx, and wherein controlling the quantity comprises controlling a value of max- HARQ-Tx. The method of claim 2, wherein the UE has a default value of max-HARQ-Tx configured by the access node, and wherein controlling by the UE the quantity of retransmission-grant windows after the scheduled uplink transmission in each of which the UE will monitor for receipt of a respective retransmission grant from the access node comprises reducing the configured value of max-HARQ-Tx to a value lower than the default value.

4. The method of claim 3, wherein the reducing of the configured value of max-HARQ-Tx to the value lower than the default value is based at least on a determination by the UE that the UE has at least threshold high uplink air-interface quality. The method of claim 1, wherein monitoring the extent to which the UE receives retransmission grants from the access node before the scheduled uplink transmission is on a per-uplink-transmission-transaction basis.

6. The method of claim 5, wherein each uplink-transmission transaction is a respective hybrid automatic repeat request (HARQ) process.Attorney Docket No.24-0613-WO 7. The method of claim 1, further comprising performing the monitoring over a sliding window defined as a multiple of connected-mode-discontinuous-reception (cDRX) cycles configured for the UE.

8. The method of claim 1, wherein the quantity of retransmission-grant windows after the scheduled uplink transmission in each of which the UE will monitor for receipt of a respective retransmission grant from the access node is in addition to any connected-mode- discontinuous-reception (cDRX) on-duration-time (ODT) in which the UE will monitor for scheduling directives from the access node.

9. The method of claim 1, wherein using by the UE the monitored extent to which the UE receives retransmission grants as a basis to control by the UE the quantity of retransmission-grant windows after the scheduled uplink transmission in each of which the UE will monitor for receipt of a respective retransmission grant from the access node comprises: making a determination by the UE of whether the monitored extent satisfies a predefined low threshold level; if the determination is negative, then, based at least on the determination, operating by the UE with the quantity set to a first quantity; and if the determination is affirmative, then, based at least on the determination, operating by the UE with the quantity set to a second quantity less than the first quantity.

10. The method of claim 9, wherein the predefined low threshold level is zero, the first quantity is non-zero, and the second quantity is zero.

11. The method of claim 10, further comprising: monitoring by the UE for retransmission grant reception from the access node within at least one connected-mode-discontinuous-reception (cDRX) on-duration time (ODT) separate from the quantity of retransmission-grant windows.

12. The method of claim 9, wherein using by the UE the monitored extent to which the UE receives retransmission grants as a basis to control by the UE the quantity of retransmission-grant windows after the scheduled uplink transmission in each of which the UEAttorney Docket No.24-0613-WO will monitor for receipt of a respective retransmission grant from the access node further comprises, if the determination is affirmative and the UE therefore operates with the quantity set to the second quantity less than the first quantity: detecting receipt by the UE of at least one retransmission grant, through monitoring by the UE during a connected-mode-discontinuous-reception (cDRX) on-duration time (ODT) after passing of the second quantity of retransmission-grant windows; and responsive to at least the detecting, switching by the UE to operate with the quantity set to the first quantity rather than the second quantity.

13. The method of claim 1, wherein using by the UE the monitored extent to which the UE receives retransmission grants as a basis to control by the UE the quantity of retransmission-grant windows after the scheduled uplink transmission in each of which the UE will monitor for receipt of a respective retransmission grant from the access node comprises: based at least on the monitored extent, operating by the UE with the quantity set to the monitored extent.

14. A user equipment device (UE) comprising: a wireless communication interface through which to engage in air-interface communication; at least one processor; non-transitory data storage; and program instructions stored in the non-transitory data storage and executable by the at least one processor to cause the UE to carry out operations to control how long the UE will monitor for retransmission grant reception after engaging in a scheduled uplink transmission to an access node serving the UE, the operations comprising: monitoring an extent to which the UE receives retransmission grants from the access node before the scheduled uplink transmission, and using the monitored extent to which the UE receives retransmission grants as a basis to control a quantity of retransmission-grant windows after the scheduled uplink transmission in each of which the UE will monitor for receipt of a respective retransmission grant from the access node.Attorney Docket No.24-0613-WO 15. The UE of claim 14, wherein the quantity is N-1, wherein N = max-HARQ-Tx, and wherein controlling the quantity comprises controlling a value of max-HARQ-Tx.

16. The UE of claim 15, wherein the UE has a default value of max-HARQ-Tx configured by the access node, and wherein controlling the quantity of retransmission-grant windows after the scheduled uplink transmission in each of which the UE will monitor for receipt of a respective retransmission grant from the access node comprises reducing the configured value of max-HARQ-Tx to a value lower than the default value.

17. The UE of claim 14, wherein the quantity of retransmission-grant windows after the scheduled uplink transmission in each of which the UE will monitor for receipt of a respective retransmission grant from the access node is in addition to any connected-mode- discontinuous-reception (cDRX) on-duration-time (ODT) in which the UE will monitor for scheduling directives from the access node.

18. Non-transitory data storage holding program instructions executable by at least one processor of a user equipment device (UE) to carry out operations to control how long the UE will monitor for retransmission grant reception after engaging in a scheduled uplink transmission to an access node serving the UE, the operations comprising: monitoring an extent to which the UE receives retransmission grants from the access node before the scheduled uplink transmission; and using the monitored extent to which the UE receives retransmission grants as a basis to control a quantity of retransmission-grant windows after the scheduled uplink transmission in each of which the UE will monitor for receipt of a respective retransmission grant from the access node.

19. The non-transitory data storage of claim 18, wherein the quantity is N-1, wherein N = max-HARQ-Tx, and wherein controlling the quantity comprises controlling a value of max-HARQ-Tx.

20. The non-transitory data storage of claim 19, wherein the UE has a default value of max-HARQ-Tx configured by the access node, and wherein controlling the quantity of retransmission-grant windows after the scheduled uplink transmission in each of which the UEAttorney Docket No.24-0613-WO will monitor for receipt of a respective retransmission grant from the access node comprises reducing the configured value of max-HARQ-Tx to a value lower than the default value.

21. A computer program comprising program instructions executable by a processor of the UE to perform a method according to any of claims 1-13.

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