WO2020263551A1

WO2020263551A1 - User equipment-requested semi-persistent scheduling

Info

Publication number: WO2020263551A1
Application number: PCT/US2020/036686
Authority: WO
Inventors: Jibing Wang; Erik Richard Stauffer
Original assignee: Google LLC
Current assignee: Google LLC
Priority date: 2019-06-28
Filing date: 2020-06-08
Publication date: 2020-12-30
Anticipated expiration: 2021-12-28

Abstract

This document describes techniques of user equipment-requested semi-persistent scheduling, for transmitting uplink data by a user equipment (110) using semi-persistent scheduling. The user equipment (110) receives a resource grant of air interface resources for uplink transmissions using semi-persistent scheduling and transmits, to a base station (121), a first command indicating the user equipment (110) will perform an uplink transmission using the received resource grant at a first time offset after transmitting the first command. The user equipment (110) transmits data at the first time offset using the air interface resources of the received resource grant. The user equipment (110) receives, at a second time offset after transmitting the first command, an indication of whether the base station (121) correctly received the transmission of the data.

Description

USER EQUIPMENT-REQUESTED SEMI-PERSISTENT SCHEDULING

BACKGROUND

[0001] The evolution of wireless communication to fifth generation (5G) standards and technologies provides higher data rates and greater capacity with improved reliability and lower latency which enhances mobile broadband services. 5G technologies also provide new classes of services for vehicular networking, fixed wireless broadband, and the Internet of Things (IoT).

[0002] A unified air interface, which utilizes licensed, unlicensed, and shared license radio spectrum in multiple frequency bands is one aspect of enabling the capabilities of 5G systems. The 5G air interface utilizes radio spectrum in bands below 1 GHz (sub-gigahertz), below 6 GHz (sub-6 GHz), and above 6 GHz. Radio spectrum above 6 GHz includes millimeter wave (mmWave) frequency bands that provide wide channel bandwidths to support higher data rates for wireless broadband.

[0003] Wireless networks use semi-persistent scheduling to support applications that require low latency operation, such as Voice over Internet Protocol (VoIP), where data packet size is small, and control signaling overhead is burdensome for packets with small inter-arrival times. Typically, base stations use semi-persistent scheduling to allocate resources at the time of dedicated bearer establishment for an application, such as a VoIP call, instead of allocating the resources periodically. A user equipment can then use the semi -persistently scheduled resources on the dedicated bearer, as needed. However, for some applications, such as on-line gaming, the base station lacks visibility into the uplink resource requirements of the user equipment to appropriately schedule uplink resources, which affects the responsiveness of the application to user inputs and diminishes the user experience with the application. SUMMARY

[0004] This summary is provided to introduce simplified concepts of user equipment-requested semi-persistent scheduling. The simplified concepts are further described below in the Detailed Description. This summary is not intended to identify essential features of the claimed subject matter, nor is it intended for use in determining the scope of the claimed subject matter.

[0005] In aspects, methods, devices, systems, and means for transmitting uplink data by a user equipment using semi -persistent scheduling are described in which the user equipment receives a resource grant of air interface resources for uplink transmissions using semi-persistent scheduling. The user equipment transmits, to a base station, a first command indicating the user equipment will perform an uplink transmission using the resource grant at a first time offset after transmitting the first command. The user equipment transmits data at the first time offset and receives, at a second time offset after transmitting the data, an indication of whether the base station correctly received the transmission of the data.

[0006] In other aspects, methods, devices, systems, and means for receiving uplink data by a base station using semi -persistent scheduling are described in which the base station transmits a resource grant of air interface resources for uplink transmissions using semi-persistent scheduling to a user equipment. The base station receives a first command indicating the user equipment will perform an uplink transmission using the resource grant at a first time offset after receiving the first command. The base station receives data at the first time offset using the air interface resources of the resource grant. The base station transmits, at a second time offset after the receiving the data, an indication of whether the base station correctly received the data. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Aspects of user equipment-requested semi-persistent scheduling are described with reference to the following drawings. The same numbers are used throughout the drawings to reference like features and components:

FIG. 1 illustrates an example wireless network environment in which various aspects of user equipment-requested semi-persistent scheduling can be implemented.

FIG. 2 illustrates an example device diagram that can implement various aspects of user equipment-requested semi-persistent scheduling.

FIG. 3 illustrates an air interface resource that extends between a user equipment and a base station and with which various aspects of user equipment- requested semi-persistent scheduling techniques can be implemented.

FIG. 4 illustrates an example block diagram of a wireless network stack model that characterizes a communication system with which various aspects of user equipment-requested semi-persistent scheduling can be implemented.

FIG. 5 illustrates example details of data and control transactions between devices of user equipment-requested semi-persistent scheduling in accordance with aspects of the techniques described herein.

FIG. 6 illustrates an example method of user equipment-requested semi- persistent scheduling as generally related to uplink semi -persistent scheduled transmissions by a user equipment in accordance with aspects of the techniques described herein.

FIG. 7 illustrates an example method of user equipment-requested semi- persistent scheduling as generally related to reception, by a base station, of semi-persistently scheduled uplink transmissions from a user equipment in accordance with aspects of the techniques described herein. DETAILED DESCRIPTION

Overview

[0008] This document describes techniques of user equipment-requested semi- persistent scheduling for transmitting uplink data by a user equipment using semi- persistent scheduling. The user equipment (UE) receives a resource grant of air interface resources for uplink transmissions using semi -persistent scheduling (SPS) and transmits, to a base station, a first command indicating the user equipment will perform an uplink transmission using the received resource grant at a first time offset after transmitting the first command. The user equipment transmits data at the first time offset using the air interface resources of the received resource grant and receives, at a second time offset after transmitting the first command, an indication of whether the transmission of the data was received correctly by the base station.

[0009] In aspects, user equipment-requested semi-persistent scheduling is described in which the user equipment transmits an uplink control channel instruction to start semi-persistently scheduled uplink transmissions. The user equipment can also transmit an uplink control channel instruction to stop semi-persistently scheduled uplink transmissions. By enabling the user equipment to control semi-persistently scheduled uplink transmissions, instead of relying solely on a base station to control when these transmissions are initiated and terminated, the user equipment and applications executing on the user equipment benefit from reduced latency and improved real-time determinism when initiating semi-persistently scheduled uplink transmissions.

[0010] While features and concepts of the described systems and methods for user equipment-requested semi-persistent scheduling can be implemented in any number of different environments, systems, devices, and/or various configurations, aspects of user equipment-requested semi-persistent scheduling are described in the context of the following example devices, systems, and configurations.

Example Environment

[0011] FIG. 1 illustrates an example environment 100, which includes a user equipment 110 (UE 110) that can communicate with base stations 120 (illustrated as base stations 121 and 122) through wireless communication links 130 (wireless link 130), illustrated as wireless links 131 and 132. For simplicity, the UE 110 is implemented as a smartphone but may be implemented as any suitable computing or electronic device, such as a mobile communication device, modem, cellular phone, gaming device, navigation device, media device, laptop computer, desktop computer, tablet computer, smart appliance, vehicle-based communication system, or an Internet- of-Things (IoT) device such as a sensor or an actuator. The base stations 120 (e.g, an Evolved Universal Terrestrial Radio Access Network Node B, E-UTRAN Node B, evolved Node B, eNodeB, eNB, Next Generation Node B, gNode B, gNB, or the like) may be implemented in a macrocell, microcell, small cell, picocell, and the like, or any combination thereof.

[0012] The base stations 120 communicate with the user equipment 110 using the wireless links 131 and 132, which may be implemented as any suitable type of wireless link. The wireless links 131 and 132 include control and data communication, such as downlink of data and control information communicated from the base stations 120 to the user equipment 110, uplink of other data and control information communicated from the user equipment 110 to the base stations 120, or both. The wireless links 130 may include one or more wireless links (e.g, radio links) or bearers implemented using any suitable communication protocol or standard, or combination of communication protocols or standards, such as 3rd Generation Partnership Project Long-Term Evolution (3GPP LTE), Fifth Generation New Radio (5G R), and so forth. Multiple wireless links 130 may be aggregated in a carrier aggregation to provide a higher data rate for the LIE 110. Multiple wireless links 130 from multiple base stations 120 may be configured for Coordinated Multipoint (CoMP) communication with the UE 110.

[0013] The base stations 120 are collectively a Radio Access Network 140 ( e.g RAN, Evolved Universal Terrestrial Radio Access Network, E-UTRAN, 5G NR RAN or NR RAN). The base stations 121 and 122 in the RAN 140 are connected to a core network 150. The base stations 121 and 122 connect, at 102 and 104 respectively, to the core network 150 through an NG2 interface for control -plane signaling and using an NG3 interface for user-plane data communications when connecting to a 5G core network, or using an SI interface for control-plane signaling and user-plane data communications when connecting to an Evolved Packet Core (EPC) network. The base stations 121 and 122 can communicate using an Xn Application Protocol (XnAP) through an Xn interface, or using an X2 Application Protocol (X2AP) through an X2 interface, at 106, to exchange user-plane and control -plane data. The user equipment 110 may connect, via the core network 150, to public networks, such as the Internet 160 to interact with a remote service 170.

Example Devices

[0014] FIG. 2 illustrates an example device diagram 200 of the user equipment 110 and the base stations 120. The user equipment 110 and the base stations 120 may include additional functions and interfaces that are omitted from FIG. 2 for the sake of clarity. The user equipment 110 includes antennas 202, a radio frequency front end 204 (RF front end 204), an LTE transceiver 206, and a 5G NR transceiver 208 for communicating with base stations 120 in the RAN 140. The RF front end 204 of the user equipment 110 can couple or connect the LTE transceiver 206, and the 5G NR transceiver 208 to the antennas 202 to facilitate various types of wireless communication. The antennas 202 of the user equipment 110 may include an array of multiple antennas that are configured similar to or differently from each other. The antennas 202 and the RF front end 204 can be tuned to, and/or be tunable to, one or more frequency bands defined by the 3GPP LTE and 5G NR communication standards and implemented by the LTE transceiver 206, and/or the 5G R transceiver 208. Additionally, the antennas 202, the RF front end 204, the LTE transceiver 206, and/or the 5G R transceiver 208 may be configured to support beamforming for the transmission and reception of communications with the base stations 120. By way of example and not limitation, the antennas 202 and the RF front end 204 can be implemented for operation in sub-gigahertz bands, sub-6 GHZ bands, and/or above 6 GHz bands that are defined by the 3GPP LTE and 5G NR communication standards.

[0015] The user equipment 110 also includes processor(s) 210 and computer- readable storage media 212 (CRM 212). The processor 210 may be a single core processor or a multiple core processor composed of a variety of materials, such as silicon, polysilicon, high-K dielectric, copper, and so on. The computer-readable storage media described herein excludes propagating signals. CRM 212 may include any suitable memory or storage device such as random-access memory (RAM), static RAM (SRAM), dynamic RAM (DRAM), non-volatile RAM (NVRAM), read-only memory (ROM), or Flash memory useable to store device data 214 of the user equipment 110. The device data 214 includes user data, multimedia data, beamforming codebooks, applications, and/or an operating system of the user equipment 110, which are executable by processor(s) 210 to enable user-plane communication, control-plane signaling, and user interaction with the user equipment 110. [0016] In some implementations, the CRM 212 may also include a scheduling manager 216. Alternately or additionally, the scheduling manager 216 may be implemented in whole or part as hardware logic or circuitry integrated with or separate from other components of the user equipment 110. The scheduling manager 216 can communicate with the antennas 202, the RF front end 204, the LTE transceiver 206, and/or the 5G NR transceiver 208 to implement techniques for user equipment- requested semi-persistent scheduling described herein.

[0017] The device diagram for the base stations 120, shown in FIG. 2, includes a single network node ( e.g ., a gNode B). The functionality of the base stations 120 may be distributed across multiple network nodes or devices and may be distributed in any fashion suitable to perform the functions described herein. The base stations 120 include antennas 252, a radio frequency front end 254 (RF front end 254), one or more LTE transceivers 256, and/or one or more 5G NR. transceivers 258 for communicating with the UE 110. The RF front end 254 of the base stations 120 can couple or connect the LTE transceivers 256 and the 5G NR transceivers 258 to the antennas 252 to facilitate various types of wireless communication. The antennas 252 of the base stations 120 may include an array of multiple antennas that are configured similar to or differently from each other. The antennas 252 and the RF front end 254 can be tuned to, and/or be tunable to, one or more frequency bands defined by the 3GPP LTE and 5G NR communication standards and implemented by the LTE transceivers 256, and/or the 5G NR transceivers 258. Additionally, the antennas 252, the RF front end 254, the LTE transceivers 256, and/or the 5G NR transceivers 258 may be configured to support beamforming, such as Massive-MIMO, for the transmission and reception of communications with the UE 110.

[0018] The base stations 120 also include processor(s) 260 and computer- readable storage media 262 (CRM 262). The processor 260 may be a single core processor or a multiple core processor composed of a variety of materials, such as silicon, polysilicon, high-K dielectric, copper, and so on. CRM 262 may include any suitable memory or storage device such as random-access memory (RAM), static RAM (SRAM), dynamic RAM (DRAM), non-volatile RAM (NVRAM), read-only memory (ROM), or Flash memory useable to store device data 264 of the base stations 120. The device data 264 includes network scheduling data, radio resource management data, beamforming codebooks, applications, and/or an operating system of the base stations 120, which are executable by processor(s) 260 to enable communication with the user equipment 110.

[0019] CRM 262 also includes a base station manager 266. Alternately or additionally, the base station manager 266 may be implemented in whole or part as hardware logic or circuitry integrated with or separate from other components of the base stations 120. In at least some aspects, the base station manager 266 configures the LTE transceivers 256 and the 5G NR transceivers 258 for communication with the user equipment 110, as well as communication with a core network, such as the core network 150. The base station manager 266 can implement the techniques for user equipment-requested semi-persistent scheduling described herein.

[0020] The base stations 120 include an inter-base station interface 268, such as an Xn and/or X2 interface, which the base station manager 266 configures to exchange user-plane and control-plane data between other base stations 120, to manage the communication of the base stations 120 with the user equipment 110. The base stations 120 include a core network interface 270 that the base station manager 266 configures to exchange user-plane and control-plane data with core network functions and/or entities. Air Interface Resources

[0021] FIG. 3 illustrates an air interface resource that extends between a user equipment and a base station and with which various aspects of user equipment- requested semi-persistent scheduling can be implemented. The air interface resource 302 can be divided into resource units 304, each of which occupies some intersection of frequency spectrum and elapsed time. A portion of the air interface resource 302 is illustrated graphically in a grid or matrix having multiple resource blocks 310, including example resource blocks 311, 312, 313, 314. An example of a resource unit 304 therefore includes at least one resource block 310. As shown, time is depicted along the horizontal dimension as the abscissa axis, and frequency is depicted along the vertical dimension as the ordinate axis. The air interface resource 302, as defined by a given communication protocol or standard, may span any suitable specified frequency range, and/or may be divided into intervals of any specified duration. Increments of time can correspond to, for example, milliseconds (mSec). Increments of frequency can correspond to, for example, megahertz (MHz).

[0022] In example operations generally, the base stations 120 allocate portions e.g ., the resource units 304) of the air interface resource 302 for uplink and downlink communications. Each resource block 310 of network access resources may be allocated to support respective wireless communication links 130 of multiple user equipment 110. In the lower left corner of the grid, the resource block 311 may span, as defined by a given communication protocol, a specified frequency range 306 and comprise multiple subcarriers or frequency sub-bands. The resource block 311 may include any suitable number of subcarriers (e.g. , 12) that each correspond to a respective portion (e.g, 15 kHz) of the specified frequency range 306 (e.g, 180 kHz). The resource block 311 may also span, as defined by the given communication protocol, a specified time interval 308 or time slot (e.g. , lasting approximately one-half millisecond or 7 orthogonal frequency-division multiplexing (OFDM) symbols). The time interval 308 includes subintervals that may each correspond to a symbol, such as an OFDM symbol. As shown in FIG. 3, each resource block 310 may include multiple resource elements 320 (REs) that correspond to, or are defined by, a subcarrier of the frequency range 306 and a subinterval (or symbol) of the time interval 308. Alternatively, a given resource element 320 may span more than one frequency subcarrier or symbol. Thus, a resource unit 304 may include at least one resource block 310, at least one resource element 320, and so forth.

[0023] In example implementations, multiple user equipment 110 (one of which is shown) are communicating with the base stations 120 (one of which is shown) through access provided by portions of the air interface resource 302. The base station manager 266 (shown in FIG. 2) may determine a respective data-rate, type of information, or amount of information ( e.g ., data or control information) to be communicated (e.g., transmitted) by the user equipment 110. For example, the base station manager 266 can determine that each user equipment 110 is to transmit at a different respective data rate or transmit a different respective amount of information. The base station manager 266 then allocates one or more resource blocks 310 to each user equipment 110 based on the determined data rate or amount of information.

[0024] Additionally, or in the alternative to block-level resource grants, the base station manager 266 may allocate resource units at an element-level. Thus, the base station manager 266 may allocate one or more resource elements 320 or individual subcarriers to different user equipment 110. By so doing, one resource block 310 can be allocated to facilitate network access for multiple user equipment 110. Accordingly, the base station manager 266 may allocate, at various granularities, one or up to all subcarriers or resource elements 320 of a resource block 310 to one user equipment 110 or divided across multiple user equipment 110, thereby enabling higher network utilization or increased spectrum efficiency.

[0025] The base station manager 266 can therefore allocate air interface resource 302 by resource unit 304, resource block 310, frequency carrier, time interval, resource element 320, frequency subcarrier, time subinterval, symbol, spreading code, some combination thereof, and so forth. Based on respective allocations of resource units 304, the base station manager 266 can transmit respective messages to the multiple user equipment 110 indicating the respective allocation of resource units 304 to each user equipment 110. Each message may enable a respective user equipment 110 to queue the information or configure the LTE transceiver 206 and/or 5G NR transceiver 208 to communicate via the allocated resource units 304 of the air interface resource 302.

User Plane and Control Plane Signaling

[0026] FIG. 4 illustrates an example block diagram 400 of a wireless network stack model 400 (stack 400). The stack 400 characterizes a communication system for the example environment 100, in which various aspects of user equipment-requested semi-persistent scheduling can be implemented. The stack 400 includes a user plane 402 and a control plane 404. Upper layers of the user plane 402 and the control plane 404 share common lower layers in the stack 400. Wireless devices, such as the UE 110 or the base stations 120, implement each layer as an entity for communication with another device using the protocols defined for the layer. For example, a UE 110 uses a Packet Data Convergence Protocol (PDCP) entity to communicate to a peer PDCP entity in a base station 120 using the PDCP.

[0027] The shared lower layers include a physical (PHY) layer 406, a Media Access Control (MAC) layer 408, a Radio Link Control (RLC) layer 410, and a PDCP layer 412. The PHY layer 406 provides hardware specifications for devices that communicate with each other. As such, the PHY layer 406 establishes how devices connect to each other, assists in managing how communication resources are shared among devices, and the like.

[0028] The MAC layer 408 specifies how data is transferred between devices. Generally, the MAC layer 408 provides a way in which data packets being transmitted are encoded and decoded into bits as part of a transmission protocol.

[0029] The RLC layer 410 provides data transfer services to higher layers in the stack 400. Generally, the RLC layer 410 provides error correction, packet segmentation and reassembly, and management of data transfers in various modes, such as acknowledged, unacknowledged, or transparent modes.

[0030] The PDCP layer 412 provides data transfer services to higher layers in the stack 400. Generally, the PDCP layer 412 provides transfer of user plane 402 and control plane 404 data, header compression, ciphering, and integrity protection.

[0031] Above the PDCP layer 412, the stack splits into the user-plane 402 and the control-plane 404. Layers of the user plane 402 include an optional Service Data Adaptation Protocol (SDAP) layer 414, an Internet Protocol (IP) layer 416, a Transmission Control Protocol/User Datagram Protocol (TCP/UDP) layer 418, and an application layer 420, which transfers data using the wireless link 130. The optional SDAP layer 414 is present in 5G NR networks. The SDAP layer 414 maps a Quality of Service (QoS) flow for each data radio bearer and marks QoS flow identifiers in uplink and downlink data packets for each packet data session. The IP layer 416 specifies how the data from the application layer 420 is transferred to a destination node. The TCP/UDP layer 418 is used to verify that data packets intended to be transferred to the destination node reached the destination node, using either TCP or UDP for data transfers by the application layer 420. In some implementations, the user plane 402 may also include a data services layer (not shown) that provides data transport services to transport application data, such as IP packets including web browsing content, video content, image content, audio content, or social media content.

[0032] The control plane 404 includes a Radio Resource Control (RRC) layer 424 and a Non-Access Stratum (NAS) layer 426. The RRC layer 424 establishes and releases connections and radio bearers, broadcasts system information, or performs power control. The RRC layer 424 also controls a resource control state of the UE 110 and causes the UE 110 to perform operations according to the resource control state. Example resource control states include a connected state ( e.g ., an RRC connected state) or a disconnected state, such as an inactive state (e.g., an RRC inactive state) or an idle state (e.g, an RRC idle state). In general, if the UE 110 is in the connected state, the connection with the base station 120 is active. In the inactive state, the connection with the base station 120 is suspended. If the UE 1 10 is in the idle state, the connection with the base station 120 is released. Generally, the RRC layer 424 supports 3GPP access but does not support non-3GPP access (e.g, WLAN communications).

[0033] The NAS layer 426 provides support for mobility management (e.g, using a Fifth-Generation Mobility Management (5GMM) layer 428) and packet data bearer contexts (e.g, using a Fifth-Generation Session Management (5GSM) layer 430) between the UE 110 and entities or functions in the core network, such as the Access and Mobility Management Function of the core network 150 or the like. The NAS layer 426 supports both 3GPP access and non-3GPP access.

[0034] In the UE 110, each layer in both the user plane 402 and the control plane 404 of the stack 400 interacts with a corresponding peer layer or entity in the base station 120, a core network entity or function, and/or a remote service, to support user applications and control operation of the UE 110 in the RAN 140. User Equipment-Requested Semi-Persistent Scheduling

[0035] FIG. 5 illustrates data and control transactions between a user equipment 110 and a base station 121 and with which various aspects of user equipment-requested semi-persistent scheduling can be implemented. In aspects, user equipment-requested semi-persistent scheduling is described in which the user equipment 110 controls when uplink data is transmitted using resources that are granted by the base station 121 for semi-persistent scheduling (SPS).

[0036] The base station 121 transmits a resource grant (resource pre-grant 505) of SPS air interface resources 302 to the user equipment 110. The resource grant can be communicated in a Radio Resource Control (RRC) message. The resource grant may be included in an uplink grant of other air interface resources 302 or may be a separate uplink grant of air interface resources 302 for SPS uplink transmissions by the user equipment 110. The base station 121 may grant the SPS resources for a limited time period (time window). The base station 121 may also revoke the grant, for example, if the base station 121 determines that the UE 110 is not using or is making limited use of the SPS resources granted at 505.

[0037] At 510, the user equipment 110 determines to start uplink transmissions using semi-persistently scheduled resources. For example, a user starts playing an on line game application on the user equipment 110 that requires low-latency uplink communications of the user’s control inputs for the game. Other examples for when the user equipment might want to request semi-persistently scheduled resources include interactive video chat, industrial robotics, and automated (or semi-automated) driving systems.

[0038] At 515, the user equipment 110 transmits a control channel command indicating to the base station 121 that the user equipment 110 is starting uplink transmissions using at least a portion of the semi-persistently scheduled resources (SPS uplink transmissions) indicated in the resource grant 505. For example, the user equipment 110 transmits a Start-SPS-Uplink command to the base station 121 as a layer 2 (MAC layer 408) control element or using layer 1 (physical layer 406) signaling, to indicate that the user equipment 110 is starting uplink transmissions using the semi- persistently scheduled resources. The user equipment 110 autonomously determines to begin and then begins SPS uplink transmissions without waiting for instructions, signaling, or an acknowledgement of the Start-SPS-Uplink command on a downlink control channel from the base station 121, which reduces latency and improves real time determinism for the user equipment 110 when initiating semi -persistently scheduled uplink transmissions. Optionally or additionally, the Start-SPS-Uplink command may include a request for an indication (acknowledgement/negative acknowledgment, ACK/NACK) from the base station as to whether SPS uplink transmission(s) are correctly received, an indication of a time offset (“time offset 2” at 530) at which the base station transmits the ACK or NACK, or both the request for the indication and the time offset.

[0039] Alternatively, the transmission of the control channel command at 515 can trigger the base station 121 to transmit a command to the user equipment (not shown), on a downlink control channel, to start SPS uplink transmissions at the first, fixed time offset. The trigger may automatically trigger the base station, or the trigger may have dependencies such that the base station does not immediately transmit a command to the user equipment.

[0040] At a first, fixed time offset (“time offset 1” at 520) after transmitting the Start-SPS-Uplink command, the user equipment 110 transmits data as an SPS uplink transmission at 525. The Start-SPS-Uplink command may include an indication of a value of the first time offset ( e.g ., two mSec or four mSec) which may be based on the latency requirements of the application transmitting data using the SPS uplink resources. Alternatively, the value of the first time offset may be determined in any suitable manner, such as being determined by the base station 121 and included in the resource grant 505, negotiated by the user equipment 110 and the base station 121 (not shown), or the like. Optionally or additionally, the SPS uplink transmission at 525 may include a request for an indication (ACK/NACK) from the base station as to whether the SPS uplink transmission is correctly received, an indication of a time offset (“time offset 2” at 530) at which the base station will transmit the ACK or NACK, or both the request for the indication and the time offset.

[0041] In another aspect, the user equipment 110 can request a downlink acknowledgement/negative acknowledgment (ACK/NACK at 535) for each SPS uplink transmission at a second, fixed time offset (“time offset 2” at 530) after each respective SPS uplink transmission. The user equipment 1 10 can request the ACK/NACK by sending a layer 3 (RLC layer 410) message or a layer 2 (MAC layer 408) control element to the base station 121. The UE 110 can specify the value of the second time offset in the layer 3 message or the layer 2 control element. The value of the second time offset may be the same as the value of the first time offset or different than the value of the first time offset.

[0042] If needed, a retransmission of the data at 545 included in the SPS uplink transmission ( e.g ., in response to receiving a downlink NACK of the original SPS uplink transmission) occurs after a third, fixed time offset (“time offset 3” at 540) after the respective SPS uplink transmission. The user equipment 110 can request the third time offset for the SPS uplink retransmission by sending a layer 3 (RLC layer 410) message or a layer 2 (MAC layer 408) control element to the base station 121. The value of the third time offset may be different than the value of the first or second time offsets and may be chosen to support the latency requirements of the user’s application. [0043] The downlink acknowledgement/negative acknowledgment (ACK/NACK at 555) for the SPS uplink retransmission occurs at a fourth, fixed time offset (“time offset 4” at 550) after the SPS uplink retransmission. The time offset for the downlink ACK/NACK (“time offset 4” at 550) can be the same or different than the second time offset (“time offset 2” at 530).

[0044] Although a single SPS uplink transmission is shown in FIG. 5, the user equipment 110 can make any number of SPS uplink transmissions, including retransmissions as needed, using the semi-persistently scheduled resources granted at 505. At 560, the user equipment 110 determines to stop uplink transmissions using the semi-persistently scheduled resources. For example, the user stops playing the on-line game application on the user equipment 110, ends the video chat, or shuts down the controller for the robot or driving system. At 565, the user equipment 110 transmits a control channel command indicating to the base station 121 that the user equipment 110 is stopping uplink transmissions using the semi-persistently scheduled resources. For example, the user equipment 110 transmits a Stop-SPS-Uplink command to the base station 121 as a layer 2 (MAC layer 408) control element or using layer 1 (physical layer 406) signaling, to indicate that the user equipment 110 is stopping uplink transmissions using the semi-persistently scheduled resources. The user equipment 110 autonomously determines to end SPS uplink transmissions without waiting for instructions or acknowledgements of the Stop-SPS-Uplink command on a downlink control channel from the base station 121. Alternatively, the transmission of the control channel command at 565 can trigger the base station 121 to transmit an indication (not shown) using a downlink control channel command to stop SPS uplink transmissions. The trigger may automatically trigger the base station, or the trigger may have dependencies such that the base station does not immediately transmit a command to the user equipment. [0045] After transmitting the Stop-SPS-Uplink command, if the user equipment 110 determines to resume uplink transmissions using the semi -persistently scheduled resources, the user equipment 110 transmits another Start-SPS-Uplink command 515 to the base station 121 and continues to transmit using the SPS resources as described above. For example, the resource grant 505 may be valid for a specified time window. The user equipment may repeatedly start and stop transmitting using the SPS resources in the resource grant 505 as long as the resource grant 505 remains valid. If the time window for the resource grant 505 has elapsed, the user equipment 110 can request a new resource grant for SPS transmissions from the base station 121.

Example Methods

[0046] Example methods 600 and 700 are described with reference to FIGs. 6 and 7 in accordance with one or more aspects of user equipment-requested semi- persistent scheduling. The order in which the method blocks are described are not intended to be construed as a limitation, and any number of the described method blocks can be skipped or combined in any order to implement a method or an alternate method. Generally, any of the components, modules, methods, and operations described herein can be implemented using software, firmware, hardware ( e.g ., fixed logic circuitry), manual processing, or any combination thereof. Some operations of the example methods may be described in the general context of executable instructions stored on computer-readable storage memory that is local and/or remote to a computer processing system, and implementations can include software applications, programs, functions, and the like. Alternatively or in addition, any of the functionality described herein can be performed, at least in part, by one or more hardware logic components, such as, and without limitation, Field-programmable Gate Arrays (FPGAs), Application-specific Integrated Circuits (ASICs), Application-specific Standard Products (ASSPs), System- on-a-chip systems (SoCs), Complex Programmable Logic Devices (CPLDs), and the like.

[0047] FIG. 6 illustrates example method(s) 600 of user equipment-requested semi-persistent scheduling as generally related to semi -persistently scheduled (SPS) uplink transmissions by the user equipment 110. At block 602, a user equipment ( e.g . the user equipment 110) receives a resource grant of air interface resources (e.g., air interface resources 302) for SPS uplink transmissions from a base station (e.g, the base station 121). For example, the user equipment receives a resource grant in an RRC message from the base station.

[0048] At block 604, the user equipment determines to start SPS uplink transmission(s), and at block 606 the user equipment transmits a Start-SPS-Uplink command to the base station. For example, the user equipment transmits the Start-SPS- Uplink command using a layer 2 control element or using layer 1 signaling.

[0049] At block 608, the user equipment transmits data using an SPS uplink transmission. For example, the user equipment transmits the data at the first time offset 520 using the air interface resources of the received resource grant.

[0050] At block 610, the user equipment receives an acknowledgement or negative acknowledgement for the SPS uplink transmission. At block 612, the user equipment determines if a negative acknowledgement (NACK) was received. If the user equipment received the negative acknowledgement (NACK), the user equipment retransmits the data as an SPS uplink retransmission at block 614. For example, the user equipment retransmits the data at a third time offset 540 after the transmission of the data. Optionally, if an acknowledgement (ACK) was received and the SPS resource grant remains valid, the user equipment may, as shown at 622, transmit additional data by returning to block 608. Thus, when the method returns to block 608, additional data is transmitted at a time after the first time offset, but still using the SPS resource grant. The data transmitted during the first iteration of block 608 and the data transmitted during each subsequent iteration of block 608 may be distinct protocol data units.

[0051] At block 616, the user equipment receives an acknowledgement or negative acknowledgement for the SPS uplink retransmission. For example, the user equipment receives, at a fourth time offset after the retransmission of the data at 614, an indication (an ACK or a NACK) of whether the base station received correctly the retransmission of the data. Optionally, as long as the SPS resource grant remains valid, the user equipment may, as shown at 624, transmit additional data by returning to block 608.

[0052] At block 618, the user equipment determines to stop SPS uplink transmissions and at block 620 the user equipment transmits a Stop-SPS-Uplink command to the base station. For example, the user equipment transmits the Stop-SPS- Uplink command using a layer 2 control element or using layer 1 signaling. Additionally or optionally, after block 620 and as long as the SPS resource grant remains valid, the user equipment can continue to start and stop SPS uplink transmissions as shown at 626.

[0053] FIG. 7 illustrates example method(s) 700 of user equipment-requested semi-persistent scheduling as generally related to reception, by a base station, of SPS uplink transmissions from a user equipment. At block 702, the base station ( e.g ., the base station 121) transmits a resource grant of air interface resources (e.g., air interface resources 302) to a user equipment (e.g, the user equipment 110) for SPS uplink transmissions. At block 704, the base station receives a Start-SPS-Uplink command from the user equipment. For example, the base station receives the Start-SPS-Uplink command using a layer 2 control element or using layer 1 signaling. [0054] At block 706, after a first time offset (e.g., the time offset 1 at 520) the base station receives an SPS uplink transmission from the user equipment. At block 708, the base station determines if the SPS uplink transmission was received correctly.

[0055] If the SPS uplink transmission was received correctly at 708, the base station transmits an acknowledgement to the user equipment at block 710 and, if the resource grant remains valid, the base station returns to block 706 to receive additional SPS uplink transmissions, as shown at 718. If the SPS uplink transmission was not received correctly at 708, the base station transmits a negative acknowledgement to the user equipment at block 712.

[0056] If the base station transmits a negative acknowledgement to the user equipment at block 712, the base station receives an SPS uplink retransmission at block 714 and, if the resource grant remains valid, the base station returns to block 706 to receive additional SPS uplink transmissions, as shown at 720. For example, the base station receives the retransmission of the data at a third time offset 540 after the reception of the SPS uplink transmission.

[0057] At block 716, the base station receives a Stop-SPS-Uplink command from the user equipment. For example, the base station receives the Stop-SPS-Uplink command using a layer 2 control element or using layer 1 signaling. Additionally or optionally, after block 716 and as long as the SPS resource grant remains valid, the process returns to block 704 (as shown at 722) enabling the base station to receive additional SPS uplink commands and data transmissions from the user equipment as described above.

[0058] In the following some examples are described:

Example 1 : A method of transmitting uplink data by a user equipment using semi- persistent scheduling, the method comprising: receiving, by the user equipment, a resource grant of air interface resources for semi-persistently scheduled uplink transmissions;

transmitting, by the user equipment and to a base station, a first command indicating the user equipment will perform an uplink transmission using the received resource grant at a first time offset after the transmitting the first command, the transmitting the first command being effective to direct the base station to receive the uplink transmission at the first time offset;

transmitting data at the first time offset and using the air interface resources of the resource grant; and

receiving, at a second time offset after the transmitting the data, an indication of whether the base station correctly received the transmission of the data.

Example 2: The method of example 1, further comprising:

transmitting, by the user equipment, additional data using the resource grant of air interface resources for semi-persistently scheduled uplink transmissions.

Example 3: The method of example 1 or example 2, further comprising:

transmitting, by the user equipment and to the base station, a second command indicating the user equipment will stop uplink transmissions using the resource grant.

Example 4: The method of any one of the preceding examples, further comprising: requesting, by the user equipment, the indication of whether the base station correctly received the transmission of the data, the request including a value of the second time offset. Example 5: The method of example 4, wherein the transmitting the first command indicating the user equipment will perform the uplink transmission includes the requesting the indication of whether the base station correctly received the transmission of the data.

Example 6: The method of example 4, wherein the transmitting the data at the first time offset includes the requesting the indication of whether the base station correctly received the transmission of the data.

Example 7: The method of example 4, wherein the requesting the indication of whether the base station correctly received the transmission of the data comprises: transmitting the request for the indication to the base station in a layer 3 message or in a layer 2 control element.

Example 8: The method of any one of the preceding examples, wherein the indication of whether the base station correctly received the transmission of the data includes an acknowledgement or a negative acknowledgement, the method further comprising:

if the indication of whether the base station correctly received the transmission of the data includes the negative acknowledgement, retransmitting the data at a third time offset after the transmitting the data and using the air interface resources of the received resource grant; and

receiving, at a fourth time offset after the retransmitting the data, an indication of whether the retransmitted data. Example 9: The method of example 8, wherein the second time offset and the fourth time offset have the same value.

Example 10: The method of example 8, wherein the second time offset and the fourth time offset have different values.

Example 11 : The method of any one of the preceding examples, wherein the user equipment receives the resource grant of air interface resources for semi-persistently scheduled uplink transmissions in a Radio Resource Control message.

Example 12: The method of any one of the preceding examples, wherein the transmitting the first command comprises:

transmitting the first command using a layer 2 control element or using layer 1 signaling.

Example 13 : The method of any of the preceding examples, wherein the transmitting the first command triggers the base station to transmit, using a downlink control channel command, an indication to the user equipment to start semi-persistently scheduled uplink transmissions at the first time offset.

Example 14: A user equipment comprising:

a radio frequency transceiver; and

a processor and memory system comprising a scheduling manager application that is executable to configure the user equipment to perform any one of the methods of examples 1 to 13. Example 15: A method of receiving uplink data by a base station using semi- persistent scheduling, the method comprising:

transmitting, by the base station and to a user equipment, a resource grant of air interface resources for semi-persistently scheduled uplink transmissions;

receiving, by the base station, a first command indicating the user equipment will perform an uplink transmission using the resource grant at a first time offset after the receiving the first command;

receiving data at the first time offset and using the air interface resources of the resource grant; and

transmitting, at a second time offset after the receiving the data, an indication of whether the base station correctly received the data.

Example 16: The method of example 15, further comprising:

determining that the data was correctly received; and

if the data was correctly received, the transmitting the indication at the second time offset comprises transmitting an acknowledgement; or

if the data was not correctly received, the transmitting the indication at the second time offset comprises transmitting a negative acknowledgement.

Example 17: The method of example 15 or example 16, wherein if the data was not correctly received, the method further comprises:

receiving, by the base station, a retransmission of the data at a third time offset after the receiving the data and using the air interface resources of the resource grant; and transmitting, at a fourth time offset after the receiving the retransmission of the data, an indication of whether the base station correctly received the retransmission of the data.

Example 18: The method of any one of examples 15 to 17, wherein the base station transmits the resource grant of air interface resources for semi -persistently scheduled uplink transmissions in a Radio Resource Control message.

Example 19: The method of any one of examples 15 to 18, wherein the receiving the first command comprises:

receiving the first command using a layer 2 control element or using layer 1 signaling.

Example 20: The method of any one of examples 15 to 19, wherein the receiving the first command further comprises:

transmitting, by the base station, an indication to the user equipment, using a downlink control channel command, to start semi-persistently scheduled uplink transmissions that are effective to direct the user equipment to transmit the data at the first time offset.

Example 21 : A base station comprising:

a radio frequency transceiver; and

a processor and memory system comprising a base station manager application that is executable to configure the base station to perform any one of the methods of examples 15 to 20. [0059] Although aspects of user equipment-requested semi-persistent scheduling have been described in language specific to features and/or methods, the subject of the appended claims is not necessarily limited to the specific features or methods described. Rather, the specific features and methods are disclosed as example implementations of user equipment-requested semi-persistent scheduling, and other equivalent features and methods are intended to be within the scope of the appended claims. Further, various different aspects are described, and it is to be appreciated that each described aspect can be implemented independently or in connection with one or more other described aspects.

Claims

CLAIMS What is claimed is:

1. A method of transmitting uplink data by a user equipment using semi- persistent scheduling, the method comprising:

receiving, by the user equipment, a resource grant of air interface resources for semi-persistently scheduled uplink transmissions;

2. The method of claim 1, further comprising:

3. The method of claim 1 or claim 2, further comprising:

4. The method of any one of the preceding claims, further comprising: requesting, by the user equipment, the indication of whether the base station correctly received the transmission of the data, the request including a value of the second time offset.

5. The method of claim 4, wherein the transmitting the first command indicating the user equipment will perform the uplink transmission includes the requesting the indication of whether the base station correctly received the transmission of the data.

6. The method of claim 4, wherein the transmitting the data at the first time offset includes the requesting the indication of whether the base station correctly received the transmission of the data.

7. The method of claim 4, wherein the requesting the indication of whether the base station correctly received the transmission of the data comprises:

transmitting the request for the indication to the base station in a layer 3 message or in a layer 2 control element.

8. The method of any one of the preceding claims, wherein the indication of whether the base station correctly received the transmission of the data includes an acknowledgement or a negative acknowledgement, the method further comprising: if the indication of whether the base station correctly received the transmission of the data includes the negative acknowledgement, retransmitting the data at a third time offset after the transmitting the data and using the air interface resources of the received resource grant; and

receiving, at a fourth time offset after the retransmitting the data, an indication of whether the retransmitted data.

9. The method of claim 8, wherein the second time offset and the fourth time offset have the same value.

10. The method of claim 8, wherein the second time offset and the fourth time offset have different values.

11. The method of any one of the preceding claims, wherein the transmitting the first command comprises:

12. The method of any of the preceding claims, wherein the transmitting the first command triggers the base station to transmit, using a downlink control channel command, an indication to the user equipment to start semi-persistently scheduled uplink transmissions at the first time offset.

13. A user equipment comprising:

a radio frequency transceiver; and

a processor and memory system comprising a scheduling manager application that is executable to configure the user equipment to perform any one of the methods of claims 1 to 12.

14. A method of receiving uplink data by a base station using semi- persistent scheduling, the method comprising:

15. The method of claim 14, wherein the receiving the first command comprises:

16. The method of claim 14 or claim 15, wherein the receiving the first command further comprises:

17. A base station comprising:

a radio frequency transceiver; and

a processor and memory system comprising a base station manager application that is executable to configure the base station to perform any one of the methods of claims 14 to 16.

18. A computer-readable medium comprising instructions that, when executed by a processor, cause an apparatus comprising the processor to perform any of the methods of claims 1 to 12 or 14 to 16.