Implicit Radio Resource Control State Transition

Abstract

The present disclosure relates to implicit radio resource control state transitions. A wireless device is capable of establishing a radio resource control (RRC) connection with a cellular base station. It is possible to determine a data inactivity timer length and a target RRC state for an implicit RRC transition. It is possible to start a data inactivity timer with the determined data inactivity timer length. It is possible to determine that the data inactivity timer has expired. The wireless device is capable of transitioning to the target RRC state at least in part based on determining that the data inactivity timer has expired.

Description

[0001] This application is a divisional application of the patent application for invention titled "Implicit Radio Resource Control State Transition" with the application number 201980013029.4 and the filing date of February 11, 2019. Technical Field

[0002] This application relates to wireless communication, and more particularly to systems, devices, and methods for performing implicit radio resource control state transitions in a cellular communication system. Background Art

[0003] The use of wireless communication systems is growing rapidly. In recent years, wireless devices such as smart phones and tablet computers have become increasingly sophisticated. In addition to supporting telephone calls, many mobile devices (i.e., user equipment devices or UEs) now also provide access to the Internet, email, text messaging, and navigation using the Global Positioning System (GPS), and are capable of operating sophisticated applications that utilize these functions. Additionally, there are many different wireless communication technologies and wireless communication standards. Some examples of wireless communication standards include GSM, UMTS (e.g., associated with the WCDMA or TD-SCDMA air interfaces), LTE, LTE-Advanced (LTE-A), HSPA, 3GPP2 CDMA2000 (e.g., 1xRTT, 1xEV-DO, HRPD, eHRPD), IEEE 802.11 (WLAN or Wi-Fi), BLUETOOTH TM etc.

[0004] The introduction of an increasing number of features and functions in wireless communication devices also requires continuous improvement of wireless communication and improvement of wireless communication devices. It is particularly important to ensure the accuracy of the signals transmitted and received by user equipment (UE) devices (e.g., via wireless devices such as cellular phones, base stations, and relay stations used in wireless cellular communication). Additionally, increasing the functionality of UE devices can place a significant strain on the battery life of the UE devices. Therefore, it is also very important to reduce the power requirements in the design of UE devices while allowing the UE devices to maintain good transmission and reception capabilities to improve communication.

[0005] To increase coverage and better serve the increasing demands and scope of the intended use of wireless communication, in addition to the above communication standards, there are also wireless communication technologies under development, including 3GPP fifth-generation (5G) new radio (NR) communication. Therefore, there is a need to improve the areas that support such development and design. Summary of the Invention

[0006] Embodiments of systems, devices, and methods for performing implicit radio resource control state transitions in a cellular communication system are provided herein.

[0007] In some cellular communication systems, there may be several possible Radio Resource Control (RRC) states in which a wireless device can operate. For example, at least according to some embodiments, in addition to the RRC connected state, in 5G NR, it may also be possible to operate in the RRC idle or RRC inactive state. In such a scenario, for example, when there are multiple options upon release from the RRC connected state, it may be useful to provide a mechanism for the wireless device to indicate its preference for which RRC state it wants to enter as the target state upon release from the RRC connected state, and / or for the cellular network to indicate to the wireless devices served by the network which RRC state the wireless device should transition to upon release from the RRC connected state. Accordingly, according to some embodiments, such a mechanism is described herein.

[0008] Additionally, at least in some cellular deployment scenarios, it is envisioned that there may be a very high density of wireless devices, many of which may only occasionally or periodically wish to communicate a small amount of data. In such cases, simply performing via air signaling for the RRC connection release message can represent a large amount of signaling load. Accordingly, techniques for performing RRC connection release using an implicit mechanism are described herein, which can reduce the signaling load in such scenarios (and other possible scenarios), and can also potentially allow at least some wireless devices to reduce the overall power consumption by potentially accelerating their transition from the RRC connected state to a higher power efficiency RRC inactive or RRC idle state once any expected data transactions are completed.

[0009] Techniques for a wireless device to negotiate to determine a preferred discontinuous reception cycle length for use by the wireless device in the RRC inactive state are also described herein. For example, the preferred discontinuous reception cycle length may potentially be different from the discontinuous reception cycle length configured for use by the wireless device in the RRC idle state. Providing a mechanism for such negotiation can allow the wireless device to more dynamically manage its configuration, and / or can help the network distinguish devices in different RRC states based on different paging cycles and allocate a DRX duration commensurate with the device capabilities / types, for example, to more evenly distribute the paging load.

[0010] Such techniques can be used alone or in any combination as needed. According to various embodiments, a wireless device implementing such techniques can, at least in some cases, reduce the data transmission latency experienced by the wireless device, reduce the need for downlink signaling, and / or achieve a faster transition to a higher power efficiency operating state.

[0011] Note that the techniques described herein may be implemented in and / or used with several different types of devices, including but not limited to base stations, access points, cellular telephones, portable media players, tablet computers, wearable devices, and various other computing devices.

[0012] This summary is intended to provide a brief overview of some of the subject matter described in this document. Accordingly, it should be understood that the above features are merely examples and should not be construed as narrowing the scope or essence of the subject matter described by this invention in any way. Other features, aspects, and advantages of the subject matter described herein will become apparent from the following detailed description, the drawings, and the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 An exemplary (and simplified) wireless communication system is shown in accordance with some embodiments;

[0014] Figure 2 An exemplary base station communicating with an exemplary wireless user equipment (UE) device is shown in accordance with some embodiments;

[0015] Figure 3 is an exemplary block diagram of a UE in accordance with some embodiments;

[0016] Figure 4 is an exemplary block diagram of a base station in accordance with some embodiments;

[0017] Figure 5 is a communication flowchart showing an exemplary possible method for performing an implicit radio resource control state transition in a cellular communication system;

[0018] Figures 6 to 10 is a message sequence diagram showing various exemplary possible communication flows for performing an implicit radio resource control state transition in a cellular communication system; and

[0019] Figure 11 is a message sequence diagram showing an exemplary possible communication flow for negotiating a preferred discontinuous reception cycle length in a cellular communication system.

[0020] Although the features described herein are susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and are described in detail herein. However, it should be understood that the drawings and the detailed description thereof are not intended to limit this application to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the subject matter as defined by the appended claims. Detailed implementation mode

[0021] Acronyms

[0022] Throughout this disclosure, various acronyms are used. The definitions of the most prominent acronyms that may appear throughout this disclosure are as follows:

[0023] · UE: User Equipment

[0024] · RF: Radio Frequency

[0025] · BS: Base Station

[0026] · GSM: Global System for Mobile Communications

[0027] · UMTS: Universal Mobile Telecommunications System

[0028] · LTE: Long Term Evolution

[0029] · NR: New Radio

[0030] · RRC: Radio Resource Control

[0031] · DRX: Discontinuous Reception

[0032] · TX: Transmission / Transmit

[0033] · RX: Receive / Receive

[0034] · NW: Network

[0035] · LAN: Local Area Network

[0036] · WLAN: Wireless Local Area Network

[0037] · AP: Access Point

[0038] · RAT: Radio Access Technology

[0039] · IEEE: Institute of Electrical and Electronics Engineers

[0040] · Wi-Fi: Wireless Local Area Network (WLAN) RAT based on the IEEE 802.11 standard

[0041] Terms

[0042] The following is a glossary of terms that will appear in this application:

[0043] Memory medium - Any of various types of non-transitory memory devices or storage devices. The term "memory medium" is intended to include installation media such as CD-ROMs, floppy disks, or magnetic tape devices; computer system memory or random access memory such as DRAM, DDR RAM, SRAM, EDO RAM, Rambus RAM, etc.; non-volatile memory such as flash memory, magnetic media such as hard disk drives or optical storage devices; registers or other similar types of memory elements, etc. The memory medium may also include other types of non-transitory memory or combinations thereof. In addition, the memory medium may be located in a first computer system that executes a program, or may be located in a different second computer system that is connected to the first computer system via a network such as the Internet. In the latter example, the second computer system may provide program instructions to the first computer system for execution. The term "memory medium" may include two or more memory media that may reside in different locations in different computer systems connected, for example, via a network. The memory medium may store program instructions (e.g., embodied as a computer program) that may be executed by one or more processors.

[0044] Carrier medium - The memory medium as described above, and physical transmission media such as buses, networks, and / or other physical transmission media that convey signals such as electrical signals, electromagnetic signals, or digital signals.

[0045] Computer system (or computer) - Any of various types of computing systems or processing systems, including personal computer systems (PCs), mainframe computer systems, workstations, network appliances, Internet appliances, personal digital assistants (PDAs), television systems, grid computing systems, or other devices or combinations of devices. Generally, the term "computer system" may be broadly defined as any device (or combination of devices) that includes at least one processor that executes instructions from a memory medium.

[0046] User equipment (UE) (or "UE device") - Any of various types of computer systems or devices that are mobile or portable and perform wireless communication. Examples of UE devices include mobile phones or smartphones (e.g., iPhone TM , Android-based phones), tablets (e.g., iPad TM ), Samsung Galaxy TM ), portable gaming devices (e.g., Nintendo DS TM ), PlayStation Portable TM ), Gameboy Advance TM ), iPhone TM ), iPhone TM) Wearable devices (e.g., smartwatches, smart glasses), laptops, PDAs, portable Internet devices, music players, data storage devices, or other handheld devices, etc. Generally, the term "UE" or "UE device" can be broadly defined as encompassing any electronic device, computing device, and / or telecommunications device (or combination of devices) that is convenient for a user to transport and capable of wireless communication.

[0047] Wireless device - Any one of various types of computer systems or devices that perform wireless communication. The wireless device can be portable (or mobile), or can be stationary or fixed at a certain location. A UE is an example of a wireless device.

[0048] Communication device - Any one of various types of computer systems or devices that perform communication, where the communication can be wired communication or wireless communication. The communication device can be portable (or mobile), or can be stationary or fixed at a certain location. A wireless device is an example of a communication device. A UE is another example of a communication device.

[0049] Base station (BS) - The term "base station" has the full scope of its ordinary meaning and at least includes a wireless communication station that is installed at a fixed location and used for communication as part of a wireless telephone system or radio system.

[0050] Processing element - Refers to various elements or combinations of elements that can perform functions in a device (such as a user equipment device or a cellular network device). The processing element can include, for example: a processor and associated memory, parts or circuits of individual processor cores, entire processor cores, processor arrays, circuits such as ASICs (application-specific integrated circuits), programmable hardware elements such as field-programmable gate arrays (FPGAs), and any one of various combinations of the above.

[0051] Wi-Fi - The term "Wi-Fi" has the full scope of its ordinary meaning and at least includes a wireless communication network or RAT that is served by wireless LAN (WLAN) access points and provides connectivity to the Internet through these access points. Most modern Wi-Fi networks (or WLAN networks) are based on the IEEE 802.11 standard and are marketed under the name "Wi-Fi". Wi-Fi (WLAN) networks are different from cellular networks.

[0052] Automatically - refers to an action or operation performed by a computer system (e.g., software executed by a computer system) or a device (e.g., a circuit, a programmable hardware element, an ASIC, etc.) without the need for user input directly specifying or performing the action or operation. Thus, the term "automatically" is contrasted with a user manually performing or specifying an operation, where the user provides input to directly perform the operation. An automatic process can be initiated by input provided by the user, but the subsequent actions that are "automatically" performed are not specified by the user, i.e., they are not "manually" performed, where the user specifies each action to be performed. For example, a user filling out a spreadsheet by selecting each field and providing input to specify information (e.g., by typing information, selecting checkboxes, radio selections, etc.) is manually filling out the spreadsheet, even though the computer system must update the spreadsheet in response to the user's actions. The spreadsheet can be filled out automatically by a computer system, where the computer system (e.g., software executing on a computer system) analyzes the fields of the spreadsheet and fills out the spreadsheet without any user input specifying the answers to the fields. As indicated above, the user can invoke the automatic filling of the spreadsheet but does not participate in the actual filling of the spreadsheet (e.g., the user does not manually specify the answers to the fields but they are completed automatically). This specification provides various examples of operations that are automatically performed in response to actions taken by the user.

[0053] Configured to - various components can be described as "configured to" perform one or more tasks. In such an environment, "configured to" is a broad statement generally indicating "having" the "structure" to perform one or more tasks during operation. Thus, even when the component is not currently performing a task, the component can be configured to perform the task (e.g., a set of electrical conductors can be configured to electrically connect a module to another module even when the two modules are not connected). In some environments, "configured to" can be a broad recitation of a structure generally meaning "having circuitry to perform one or more tasks during operation". Thus, even when the component is not currently powered on, the component can be configured to perform the task. Generally, the circuitry forming the structure corresponding to "configured to" can include hardware circuitry.

[0054] For ease of description, various components can be described as performing one or more tasks. Such a description should be interpreted to include the phrase "configured to". A component described as configured to perform one or more tasks is explicitly intended not to invoke the interpretation of 35 U.S.C. § 112, paragraph 6, for that component.

[0055] Figure 1 and Figure 2 - Exemplary communication system

[0056] Figure 1 illustrates an exemplary (and simplified) wireless communication system that can implement various aspects of the present disclosure according to some embodiments. Note thatFigure 1 The system is merely an example of a possible system, and these embodiments may be implemented in any of a variety of systems as needed.

[0057] As shown, the exemplary wireless communication system includes a base station 102 that communicates with one or more (e.g., any number) user equipments 106A, 106B, etc. up to 106N via a transmission medium. Each user equipment may be referred to herein as a "user equipment" (UE) or UE device. Thus, the user equipment 106 is referred to as a UE or UE device.

[0058] The base station 102 may be a base transceiver station (BTS) or a cell site and may include hardware and / or software for implementing wireless communication with the UEs 106A through 106N. If the base station 102 is implemented in the context of LTE, it may be referred to as an "eNodeB" or "eNB". If the base station 102 is implemented in the context of 5G NR, it may alternatively be referred to as a "gNodeB" or "gNB". The base station 102 may also be equipped to communicate with a network 100 (e.g., the core network of a cellular service provider, a telecommunications network such as the public switched telephone network (PSTN), and / or the Internet, and various possible networks). Thus, the base station 102 may facilitate communication between user equipments and / or between user equipments and the network 100. The communication area (or coverage area) of a base station may be referred to as a "cell". Also as used herein, with respect to a UE, a base station may sometimes be considered to represent the network, taking into account the uplink and downlink communications of the UE. Thus, a UE that communicates with one or more base stations in a network may also be understood to communicate with the network.

[0059] The base station 102 and the user equipment may be configured to communicate via a transmission medium using any of a variety of radio access technologies (RATs), which are also referred to as wireless communication technologies or telecommunications standards, such as GSM, UMTS (WCDMA, TD-SCDMA), LTE, LTE-Advanced (LTE-A), LAA / LTE-U, 5G NR, 3GPP2, CDMA2000 (e.g., 1xRTT, 1xEV-DO, HRPD, eHRPD), Wi-Fi, etc.

[0060] Base stations 102 and other similar base stations operating according to the same or different cellular communication standards may thus provide, as one or more cell networks, continuous or near-continuous overlapping services to the UEs 106 and similar devices over a geographical area via one or more cellular communication standards.

[0061] Note that UE106 is capable of communicating using multiple wireless communication standards. For example, UE106 may be configured to communicate using either or both of the 3GPP cellular communication standard or the 3GPP2 cellular communication standard. In some embodiments, UE 106 may be configured to perform implicit radio resource control state transitions at least according to the various methods described herein. UE 106 may also be configured or alternatively configured to communicate using WLAN, BLUETOOTH TM , one or more global navigation satellite systems (GNSS, such as GPS or GLONASS), one and / or more mobile television broadcast standards (e.g., ATSC-M / H), etc. Other combinations of wireless communication standards (including more than two wireless communication standards) are also possible.

[0062] Figure 2 An exemplary user equipment 106 (e.g., one of devices 106A to 106N) communicating with a base station 102 according to some embodiments is shown. UE106 can be a device with wireless network connectivity, such as a mobile phone, a handheld device, a wearable device, a computer, or a tablet, or substantially any type of wireless device. UE 106 may include a processor configured to execute program instructions stored in a memory. UE 106 can perform any of the method embodiments described in the present invention by executing such stored instructions. Alternatively or in addition, UE 106 may include programmable hardware elements, such as a field programmable gate array (FPGA) configured to perform any of the method embodiments described in the present invention or any part of any of the method embodiments described in the present invention. UE106 may be configured to communicate using any one of multiple wireless communication protocols. For example, UE106 may be configured to communicate using two or more of CDMA2000, LTE, LTE-A, 5G NR, WLAN, or GNSS. Other combinations of wireless communication standards are also possible.

[0063] UE106 may include one or more antennas for communicating using one or more wireless communication protocols according to one or more RAT standards. In some embodiments, UE106 may share one or more parts of the receive chain and / or the transmit chain among multiple wireless communication standards. The shared radio components may include a single antenna or may include multiple antennas for performing wireless communication (e.g., for MIMO). Generally, the radio components may include any combination of a baseband processor, analog radio frequency (RF) signal processing circuitry (e.g., including filters, mixers, oscillators, amplifiers, etc.), or digital processing circuitry (e.g., for digital modulation and other digital processing). Similarly, the radio components may implement one or more receive chains and transmit chains using the aforementioned hardware.

[0064] In some embodiments, the UE 106 may include separate transmit chains and / or receive chains (e.g., including separate antennas and other radio components) for each wireless communication protocol it is configured to communicate with. As another possibility, the UE 106 may include one or more radio components shared among multiple wireless communication protocols, and one or more radio components uniquely used by a single wireless communication protocol. For example, the UE 106 may include shared radio components for communicating using any of LTE or CDMA2000 1xRTT (or LTE or NR, or LTE or GSM, etc.), and separate radio components for communicating using each of Wi-Fi and BLUETOOTH TM for communicating. Other configurations are possible.

[0065] Figure 3 - Block diagram of an exemplary UE device

[0066] Figure 3 FIG. shows a block diagram of an exemplary UE 106 according to some embodiments. As shown, the UE 106 may include a system on a chip (SOC) 300, which may include portions for various purposes. For example, as shown, the SOC 300 may include a processor 302 that can execute program instructions for the UE 106, and a display circuit 304 that can perform graphics processing and provide a display signal to a display 360. The processor 302 may also be coupled to a memory management unit (MMU) 340, which may be configured to receive addresses from the processor 302 and translate those addresses into locations in a memory (e.g., memory 306, read-only memory (ROM) 350, NAND flash memory 310) and / or other circuits or devices, such as the display circuit 304, radio components 330, connector I / F 320, and / or display 360. The MMU 340 may be configured to perform memory protection and page table translation or setup. In some embodiments, the MMU 340 may be included as part of the processor 302.

[0067] As shown, the SOC 300 may be coupled to various other circuits of the UE 106. For example, the UE 106 may include various types of memory (e.g., including NAND flash 310), a connector interface 320 (e.g., for coupling to a computer system, docking station, charging station, etc.), a display 360, and wireless communication circuitry 330 (e.g., for LTE, LTE-A, NR, CDMA2000, BLUETOOTH TM, Wi-Fi, GPS, etc.). The UE device 106 may include at least one antenna (such as 335a), and may include multiple antennas (such as shown by antennas 335a and 335b) for performing wireless communication with the base station and / or other devices. Antennas 335a and 335b are shown by way of example, and the UE device 106 may include fewer or more antennas. Generally speaking, one or more antennas are collectively referred to as antenna 335. For example, the UE device 106 may use antenna 335 via radio circuitry 330 to perform wireless communication. As described above, in some embodiments, the UE may be configured to perform wireless communication using multiple wireless communication standards.

[0068] As further described subsequently herein, the UE 106 (and / or the base station 102) may include hardware and software components for implementing an implicit radio resource control state transition method for at least the UE 106 to perform in a cellular communication system. One or more processors 302 of the UE device 106 may be configured to implement part or all of the methods described herein, for example by executing program instructions stored on a memory medium (e.g., a non-transitory computer-readable memory medium). In other embodiments, one or more processors 302 may be configured as programmable hardware elements, such as an FPGA (field programmable gate array) or as an ASIC (application specific integrated circuit). Additionally, as Figure 3 shown, one or more processors 302 may be coupled to other components and / or may interoperate with other components to perform an implicit radio resource control state transition in a cellular communication system according to various embodiments disclosed herein. One or more processors 302 may also implement various other applications and / or end-user applications running on the UE 106.

[0069] In some embodiments, the radio component 330 may include separate controllers dedicated to controlling communication for various corresponding RAT standards. For example, as Figure 3 shown, the radio component 330 may include a Wi-Fi controller 332, a cellular controller (such as an NR controller) 334, and a BLUETOOTH TM controller 336, and in at least some embodiments, one or more or all of these controllers may be implemented as corresponding integrated circuits (simply referred to as ICs or chips), which communicate with each other and communicate with the SOC 300 (more specifically with one or more processors 302). For example, the Wi-Fi controller 332 may communicate with the cellular controller 334 via a cell-ISM link or a WCI interface, and / or BLUETOOTH TMThe controller 336 may communicate with the cellular controller 334 via a cell-ISM link or the like. Although three separate controllers are shown within the radio component 330, other embodiments may have fewer or more similar controllers for the various different RATs that may be implemented in the UE device 106.

[0070] Figure 4 - Block diagram of an exemplary base station

[0071] Figure 4 A block diagram of an exemplary base station 102 according to some embodiments is shown. Note that Figure 4 the base station is only one example of a possible base station. As shown, the base station 102 may include a processor 404 that may execute program instructions for the base station 102. The processor 404 may also be coupled to a memory management unit (MMU) 440 or other circuits or devices, and the MMU may be configured to receive addresses from the processor 404 and translate those addresses to locations in a memory (e.g., memory 460 and read-only memory (ROM) 450).

[0072] The base station 102 may include at least one network port 470. The network port 470 may be configured to couple to a telephone network and provide access to a plurality of devices such as the UE device 106 as described herein with respect to Figure 1 and Figure 2 the telephone network. The network port 470 (or an additional network port) may also be configured or alternatively configured to couple to a cellular network, such as the core network of a cellular service provider. The core network may provide mobility-related services and / or other services to a plurality of devices such as the UE device 106. In some cases, the network port 470 may be coupled to the telephone network via the core network, and / or the core network may provide the telephone network (e.g., in other UE devices served by the cellular service provider).

[0073] Base station 102 may include at least one antenna 434 and possibly multiple antennas. One or more antennas 434 may be configured to operate as a wireless transceiver and may be further configured to communicate with UE device 106 via radio component 430. Antenna 434 communicates with radio component 430 via communication link 432. Communication link 432 may be a receive link, a transmit link, or both. Radio component 430 may be designed to communicate via various radio telecommunications standards, which include but are not limited to NR, LTE, LTE-A, WCDMA, CDMA2000, etc. Processor 404 of base station 102 may be configured to implement and / or support the implementation of part or all of the methods described herein, such as by executing program instructions stored on a memory medium (e.g., a non-transitory computer-readable memory medium). Alternatively, processor 404 may be configured as a programmable hardware element such as an FPGA (Field Programmable Gate Array), or as an ASIC (Application Specific Integrated Circuit), or a combination thereof. In the case of certain RATs (e.g., Wi-Fi), base station 102 may be designed as an access point (AP), in which case network port 470 may be implemented to provide access to a wide area network and / or one or more local area networks, e.g., it may include at least one Ethernet port, and radio component 430 may be designed to communicate according to the Wi-Fi standard. Base station 102 may operate according to various methods disclosed herein to cause a wireless device to perform an implicit radio resource control state transition in a cellular communication system.

[0074] Figure 5 —Implicit radio resource control state transition

[0075] Multiple cellular communication technologies include using a Radio Resource Control (RRC) protocol (e.g., which may facilitate connection establishment and release, radio bearer establishment, reconfiguration, and release) and / or various other possible signaling functions that support the air interface between a wireless device and a cellular base station.

[0076] A wireless device may generally operate in one of multiple possible conditions (e.g., states or modes) with respect to RRC. For simplicity, the condition of a wireless device with respect to RRC may subsequently be referred to herein as its RRC state. For example, in LTE, a wireless device may operate in an RRC connected state (e.g., where the wireless device may perform continuous data transmission and where handovers between cells are managed by the network and access stratum context information is reserved for the wireless device), or may operate in an RRC idle state (e.g., where the wireless device may operate in a more battery-efficient state when not performing continuous data transmission, where the wireless device may handle its cell reselection activities, and where the network may not reserve access stratum context information for the wireless device).

[0077] In addition to the RRC connected state and the RRC idle state, according to at least some embodiments, one or more other types of RRC states may also be supported for a wireless device. For example, for NR, an RRC inactive state may be supported, in which the wireless device may be able to operate in a relatively battery-efficient manner while the network still retains at least some access stratum context information. According to at least some embodiments, such a state may be based on the mobility of the wireless device. For example, the wireless device may be able to move within a radio access network notification area (RNA) without notifying the next generation (NG) radio access network (RAN). When in this state, the wireless device may perform cell reselection and system information acquisition for itself, for example, at least in part based on the system information broadcast by potential candidate cells. At the same time, the last served base station (e.g., gNB) may maintain the wireless device context and the NG connection to the 5G core network (CN) associated with the wireless device, for example, to facilitate an easier transition back to the RRC connected state. When paging a wireless device in the RRC inactive state, the RAN may use RNA-specific parameters, such as including UE-specific discontinuous reception (DRX) and UE identity index values (e.g., I-RNTI).

[0078] In at least some cases, using the RRC inactive state may help reduce the network signaling overhead for a wireless device connection. For example, for a wireless device with infrequent data transmissions, using this RRC inactive state can reduce the amount of mobility-related signaling (e.g., for handovers) required compared to using the RRC connected state, for example, because the wireless device may be able to manage its own cell reselection process when moving between cells. For such wireless devices, using the RRC inactive state can also reduce the amount of connection establishment-related signaling required compared to using the RRC idle state, for example, because the network can retain at least some context information for the wireless device. This can directly reduce the signaling latency associated with the transition to the RRC connected state.

[0079] As another potential benefit, for example, compared to operating in the RRC idle state, this state can reduce the control plane latency of the wireless device. For example, for the RRC inactive state relative to the RRC idle state, it is possible to shorten the access stratum connection establishment period and / or the non-access stratum connection establishment period. Therefore, the time from the battery-efficient state to the start of continuous data transmission can be reduced.

[0080] Additionally, for example, compared to operating in the RRC connected state, this state can improve the power saving ability of a wireless device. For example, compared to when in the RRC inactive state, when in the RRC connected state, services and / or neighbor cell measurements may be required more frequently, for example, at least in line with the discontinuous reception (C-DRX) cycle of the connection of the wireless device.

[0081] One use case that may be common (or become common) in a cellular communication system may include a scenario that may be referred to as a massive machine type communication (mMTC) scenario. For example, in an mMTC scenario, there is a high device density in the cellular network that tends to perform small periodic data communication activities. For such devices, once the data transmission is complete, at least as a possibility, the RRC connection of the device may be released by means of explicit RRC connection release signaling provided by the network after a pre-determined connection activity period. However, at least in some cases, with respect to the mMTC scenario, this explicit mechanism for releasing the RRC connection can result in a heavy signaling load on the network. Additionally, using a pre-determined connection inactivity period before RRC connection release can represent a potential waste of power, for example, because this can ensure that the wireless device spends at least a certain amount of time in the RRC connected state but does not perform any data activity before being released to a potentially more power-efficient RRC idle or RRC inactive state. This can be particularly costly for some machine type communication (MTC) devices that may be highly power-constrained (e.g., according to various embodiments, may have a battery life expectancy of 5 to 10 years and other possibilities).

[0082] In view of such considerations, it may be useful to provide a mechanism for a wireless device to indicate which RRC state it will preferably transition to after the RRC connection is released, for example, based on any one of its device type, current service mode, speed, motion state, mobility history, uplink and / or downlink buffer status, and / or various other considerations. Additionally, it may be useful to provide a mechanism for the wireless device and its serving base station to implement an implicit RRC connection release and possibly further negotiate how long a data inactivity period is required before continuing with the implicit RRC connection release on each side. Therefore, Figure 5 is a flowchart showing a method for a wireless device (e.g., a wireless user equipment (UE) device) to perform an implicit radio resource control state transition in a cellular communication system, which, among various possibilities, can help reduce network signaling load and / or improve the power usage efficiency of the wireless device.

[0083] Figure 5Aspects of the method may be implemented by a wireless device, e.g., in conjunction with a cellular base station (such as, with respect to UE 106 and BS 102 shown and described in the various figures herein), or more generally in conjunction with any of the computer systems or devices shown in the above figures as needed, and other devices. Note that although aspects of the method are described in a manner that involves the use of communication technologies and / or features associated with NR and / or 3GPP specification documents, such description is not intended to limit the disclosure and may be used in any suitable wireless communication system as needed. Figure 5 At least some elements of the method, however, this description is not intended to limit the present disclosure and may be used in any suitable wireless communication system as needed. Figure 5 Aspects of the method. In various embodiments, some of the method elements shown may be executed simultaneously in a different order than shown, may be replaced by other method elements, or may be omitted. Additional method elements may also be executed as needed. As shown, Figure 5 The method may operate as follows.

[0084] At 502, the wireless device may establish an RRC connection with the cellular base station. Establishing the RRC connection may include configuring various parameters for communication between the wireless device and the cellular base station, establishing environmental information of the wireless device, and / or any of various other possible features, e.g., involving establishing an air interface of the wireless device for cellular communication with a cellular network associated with the cellular base station. After establishing the RRC connection, the wireless device may operate in the RRC connected state.

[0085] At 504, the wireless device may negotiate a data inactivity period and a target RRC state for an implicit transition from the RRC connected state with the cellular base station. Such negotiation may be performed using any desired signaling mechanism, e.g., including using any of various (e.g., new or pre - existing) RRC messages and / or media access control (MAC) control elements (CEs). As one possibility, such negotiation may be performed during RRC connection establishment.

[0086] To negotiate the target RRC state, the wireless device may indicate a preferred target RRC state to transition to when released from the RRC connected state. For example, the wireless device may indicate that the preference for the target RRC state is RRC idle or RRC inactive. The preference may be selected by the wireless device based on any of various considerations, such as device type (e.g., MTC, phone, etc.), device movement history, movement / speed information (e.g., high - speed train, pedestrian, vehicle, etc.), service mode (e.g., short / long data session, periodic data, etc.). In addition or alternatively, the wireless device may provide auxiliary information to the cellular base station to assist in determining the target RRC state of the wireless device, and the auxiliary information may include information about any such parameters of the wireless device as well as various other possible types of information.

[0087] In at least some cases, the wireless device may also indicate a preferred data inactivity timer length for the wireless device. For example, this preferred data inactivity timer length may be used by the wireless device and the cellular base station as a basis for determining when an implicit RRC state transition should occur. The preferred data inactivity timer length may be determined by the wireless device based on considerations similar to those used to determine the preferred target RRC state to transition to when releasing from the RRC connected state of the wireless device, and / or may include any of a variety of other possible parameters. Additionally or alternatively, the wireless device may provide such assistance information to the cellular base station to additionally / alternatively assist in determining the data inactivity timer length for the wireless device.

[0088] The cellular base station (or more generally, the network in which the cellular base station operates) may determine, for example, at least in part based on the information provided by the wireless device, the target RRC state to transition to when releasing from the RRC connected state for the wireless device and / or the data inactivity timer length for the wireless device for an implicit RRC state transition. In other words, the cellular base station may consider any one or all of the preferred target RRC state indicated by the wireless device, the preferred data inactivity timer length indicated by the wireless device, and / or various types of assistance information provided by the wireless device (e.g., the device type of the wireless device; the mobility history information of the wireless device; the motion information of the wireless device; or the service mode of the wireless device, as well as other possible types of assistance information). Additionally or alternatively, the cellular base station may determine the target RRC state and / or the data inactivity timer length for the wireless device at least in part based on any one of a variety of additional or alternative types and / or sources of information. For example, the cellular base station may base its determination on the downlink buffer status information available for the wireless device, the network load, and / or the availability of other network resources and / or any of a variety of other considerations.

[0089] A cellular base station may indicate to a wireless device a determined target RRC state and / or a data inactivity timer length. Note that, according to various embodiments, the target RRC state determined by the cellular base station may be the same as the preferred target RRC state indicated by the wireless device, or may be a different RRC state. Similarly, the data inactivity timer length determined by the cellular base station may be the same as the requested data inactivity timer length, or may be a different data inactivity timer length. At least according to some embodiments, regardless of whether the target RRC state and / or data inactivity timer length indicated by the cellular base station matches the target RRC state and / or data inactivity timer length requested by the wireless device, the wireless device may accept the target RRC state and / or data inactivity timer length indicated by the cellular base station. For example, as a possibility, the cellular communication standard document may specify (or the cellular network operator and the wireless device vendor may otherwise agree) that the wireless device should always accept the target RRC state and data inactivity timer length parameters provided by the cellular network. Other arrangements are also possible.

[0090] The cellular base station and the wireless device may each start a data inactivity timer with a negotiated data inactivity timer length. The cellular base station and the wireless device may use the data inactivity timer to separately track whether and when the RRC connection is implicitly released. At each moment of data activity (e.g., uplink activity, downlink activity) between the wireless device and the cellular base station, each of the cellular base station and the wireless device may restart its data inactivity timer for the wireless device. Note that, among various possibilities, data activity may be determined based on either or both of physical layer (Layer 1, e.g., Hybrid Automatic Repeat reQuest (HARQ)) activity or Radio Link Control (RLC) / Media Access Control (MAC) (Layer 2 / 3) activity as needed.

[0091] Note that if the wireless device experiences movement during an RRC connection (e.g., a handover to another cell that may be served by a different cellular base station occurs), the target RRC state and data inactivity timer length information for the RRC connection (e.g., as context information of the wireless device) may be maintained such that the new serving base station can know the determined target RRC state and data inactivity timer length and may track the current data inactivity timer value for the wireless device.

[0092] Note also that, if desired, the wireless device and / or the cellular base station can avoid scheduling any uplink or downlink activity for a particular amount of time that causes the data inactivity timer used to determine when an implicit RRC state transition occurs to expire. The duration of such a restriction can be selected as desired, for example, to reduce the likelihood of possible synchronization issues that can occur when the data inactivity timer at the wireless device and the data inactivity timer at the cellular base station are slightly offset from such data activity.

[0093] In 506, when the data inactivity timer expires, the wireless device and the cellular base station can implicitly release the wireless device from the RRC connected state to a target RRC state. Thus, if the target RRC state is RRC idle, the wireless device can begin operating according to the idle timeline (e.g., after the idle discontinuous reception (DRX) paging timeline configured between the wireless device and the network), while if the target RRC state is RRC inactive, the wireless device can begin operating according to the inactive timeline (e.g., after the inactive DRX paging timeline configured between the wireless device and the network). The cellular base station can similarly follow the paging timeline appropriate for the RRC state of the wireless device and manage the context information of the wireless device according to the target RRC state. At least according to some embodiments, such an implicit RRC state transition of the wireless device to the target RRC state can be achieved, for example, with no explicit air signaling between the wireless device and the cellular base station at least at the time of the RRC state transition.

[0094] Note that, if desired, a mechanism can also be provided for the wireless device to indicate a preference for the length of the inactive DRX cycle that will be used for the wireless device when the wireless device is operating in the RRC inactive state. For example, as one possibility, the wireless device can indicate its preferred inactive DRX value in an attach request or RNA update request message (e.g., separately and in addition to its preferred idle DRX value, or implicitly by indicating its preferred idle DRX value). The network and the wireless device can determine the DRX cycle length for the wireless device to use in the RRC inactive state based at least in part on the indication of the preferred DRX cycle length (e.g., and also potentially at least in part on the network-preferred inactive DRX cycle length). For example, as one possibility, the smaller of the wireless device-preferred inactive DRX cycle length and the network-preferred inactive DRX cycle length can be selected (e.g., resulting in a shorter DRX cycle) as the DRX cycle length for the wireless device. Other methods of selecting the DRX cycle length for a wireless device in the RRC inactive state are also possible.

[0095] Note also that, while negotiation of the data inactivity timer length and the use of such a data inactivity timer to support implicit RRC state transitions, and negotiation of the target RRC state to transition to after the RRC connection is released, may be beneficial in at least some cases, negotiation of the target RRC state to transition to after the RRC connection is released can also be used in combination with explicit RRC connection release signaling techniques. For example, at least in some cases, a wireless device may be able to release from an RRC connected state to a target RRC state based at least in part on an explicit RRC connection release indication received from a cellular base station.

[0096] By using such techniques to negotiate the target RRC state and / or support implicit RRC state transitions, a wireless device may be able to transition to a high power efficiency operating state, such as an inactive or idle state, more quickly after a data communication session. For example, it may be possible to negotiate a lower data inactivity timer length for an implicit RRC state transition than may have been generated prior to the availability of an explicit RRC connection release message. Additionally, such techniques can significantly reduce the amount of air interface downlink network signaling used to provide an RRC connection release. Thus, at least according to some embodiments, the techniques described herein can reduce the signaling load on the network, improve power efficiency and / or reduce the data transmission latency of a wireless device, among other possible benefits.

[0097] Note that, as a possibility, the techniques described herein for negotiating the data inactivity timer length and / or the target RRC state can be used on a per RRC connection basis. For example, whenever a wireless device establishes an RRC connection, the wireless device may indicate its preferred target RRC state and / or data inactivity timer length and receive an indication of the target RRC state and / or data inactivity timer length selected by the network for the wireless device. This can allow a wireless device with potentially changing preferences (e.g., changing due to experiencing different service modes at different times) to more flexibly adapt to such changing preferences. Alternatively or in addition, a wireless device may be able to establish data inactivity timer length and / or target RRC state parameters that are sustainable across multiple RRC connections for the wireless device. For example, in such a case, the wireless device and the network may store such information as part of the context information of the wireless device between RRC connections. At least according to some embodiments, this can allow a wireless device with predictable preferences to avoid unnecessary signaling to renegotiate the same parameters each time an RRC connection is established.

[0098] Figures 6 to 11 — Message sequence diagrams and additional information

[0099] Figures 6 to 11 shows additional aspects that can be combined, if desired, with the Figure 5 method. However, it should be noted that inFigures 6 to 11 The exemplary details shown and described with respect to these figures are not intended to limit the present disclosure as a whole: Many variations and alternatives of the details provided below are possible and should be considered within the scope of the present disclosure.

[0100] It is expected that 5G NR processing includes use cases for mMTC scenarios. MTC devices (e.g., UEs) may typically utilize their serving network to enter the RRC connected state periodically (e.g., perhaps infrequently) for a short period of time, e.g., to exchange a small amount of data. Once the data transmission / reception is complete, among various possibilities, the network may release the UE's RRC connection after a pre-determined connection inactivity period, which may be on the order of a few seconds.

[0101] If a very high device density occurs (e.g., as a possibility, on the order of millions of devices per specific geographical area; other definitions are possible), then if explicit air interface RRC signaling messages are used, this may mean a very heavy signaling load on the air interface just for releasing the RRC connections of the devices served by the network.

[0102] In addition, such an institution may also force these devices, which may be highly power-constrained (e.g., as a possibility, the battery needs to last from 5 to 10 years; other definitions are possible), to waste unnecessary time in the RRC connected state even after the intended data transaction between the device and the network is complete. Instead, such devices may be better served by being able to transition more quickly to a higher power efficiency state (e.g., idle or inactive state). Thus, a fallback scheme is described herein that can better meet the needs of the devices served in a cellular network.

[0103] In addition to various other possible use cases, the techniques described herein may be useful for cellular devices that are wearable devices or otherwise battery-constrained and that may need to transmit very small amounts of data using their serving network at least in some cases. In such cases, such a device may be able to signal its intent to the network and attempt to complete the data transaction, such as being able to quickly fallback to a high power efficiency state, such as the RRC inactive or RRC idle state. Note that according to various embodiments, such a scheme may also or alternatively be used for any number of other possible use cases.

[0104] As part of such a scheme, a cellular device may indicate a preferred target state (e.g., RRC inactive or RRC idle) based on its traffic pattern and / or other auxiliary parameters. The network may choose to respect the device's recommendation or choose an alternative target state and may use the network-selected RRC connection release mechanism to transition the device to the requested target state.

[0105] Additional auxiliary parameters from the device can include any one of a variety of possible parameters. For example, the device type of the cellular device (e.g., MTC, phone), device movement history, device movement and speed (high-speed train, pedestrian, vehicle, etc.), service mode (short / long data session, periodic data, etc.) and / or any one of various other parameters / characteristics can be provided. At least in some cases, such auxiliary information can indicate the intention of the UE (e.g., quickly) to fallback to a high power efficiency state rather than remain in the connected state.

[0106] Among various possibilities, an explicit RRC connection release mechanism or an implicit RRC connection release mechanism can be used to achieve fallback to a specific target state. For the implicit mechanism, the cellular device and the network may be able to negotiate a threshold timer value, e.g., based on the auxiliary information provided by the device and / or the indication of the requested / preferred threshold timer value provided by the device. The threshold timer value can control when the device can automatically transition out of the RRC connection state to the target state without explicit RRC signaling from the network.

[0107] Thus, as one possibility, a solution that utilizes both the negotiation of the target state to which the cellular device is to transition after RRC connection release and the implicit RRC connection release mechanism can operate as follows. When the device is in the RRC inactive or idle state, the device can request (e.g., in any agreed RRC signaling message) a preferred data inactivity timer and a preferred RRC state fallback to when the inactivity timer expires from the network. In addition, the device can also indicate the service mode and / or any relevant auxiliary information that can help the network configure the inactivity timer and the preferred RRC state after the inactivity timer expires.

[0108] When the data inactivity timer expires, the network can respond (e.g., in any agreed RRC signaling message) with the data inactivity timer value that the device should apply and the RRC state to which the device should transition (e.g., from the RRC connected state). Note that at least according to some embodiments, regardless of the value requested by the device in the uplink, the parameters from the network can be bound to the device, e.g., parameters regarding both the data inactivity timer value and the target RRC state. For example, as mentioned above, in some cases, the cellular communication standard or other protocols between the relevant parties can specify that the wireless device must accept such network-provided parameters, e.g., in order to comply with the standard or protocol.

[0109] To ensure interoperability with other devices that do not desire to implement such a feature, it may be possible to use the encoding for the preferred data inactivity timer and the preferred state after the data inactivity timer expires as an optional (e.g., non-critical ASN.1 extension) in an uplink RRC message, and / or use the encoding for the data inactivity timer and the state after the inactivity timer expires as an optional (e.g., non-critical ASN.1 extension) in a downlink RRC message. Thus, for example, if a newly introduced information element that supports such a feature is not present in a downlink RRC signaling message, it may be assumed (e.g., by a wireless device that has provided an indication of the preferred data inactivity timer and / or the preferred state to transition to after the data inactivity timer expires) that the network does not support the feature.

[0110] As an additional or alternative feature, it may also be possible to provide a mechanism for a cellular device to negotiate the DRX duration / cycle length for the RRC inactive state. For example, according to some embodiments, when in the RRC inactive state from the network, the device may request to use the preferred DRX periodicity. Such a request may be provided in an uplink non-access stratum (NAS) message, e.g., such that the device may optionally encode the requested DRX periodicity for the RRC inactive state. The network may encode the preferred DRX periodicity for the RRC inactive state in a downlink system information message. At least according to some embodiments, the configured inactive DRX periodicity may be selected as the minimum of what the device requests in NAS signaling and what the network broadcasts in the cell system information.

[0111] Figures 6 to 11 is a message sequence diagram showing various possible scenarios that may occur between the UE and the network when implementing such a scheme. Note that although, for convenience, Figures 6 to 11 the time units represented in are shown as seconds, it should be noted that other units may also be used (e.g., among the various possibilities, according to 5G NR subframe / slot / micro-slot durations and / or with implicit offsets), and this representation should not be considered restrictive. Similarly, although parameter negotiation is shown in the illustrated figure as being performed using RRCConnectionResumeRequest / Confirm messages, such negotiation may be part of any desired RRC signaling message, e.g., including the initial RRCConnectionSetup procedure. In addition, the auxiliary information for negotiation need not be limited to the preferred data inactivity timer length and the target RRC state, but may also or alternatively include service mode and / or any other desired auxiliary information, such as device movement history, device motion, device type, etc. In other words, although Figures 6 to 11The details of the illustrated scenario may represent some possible specific implementation options, but many other details may also or alternatively be used as needed, and the overall scenario of Figures 6 to 11 should not be regarded as a limitation on the present disclosure.

[0112] Figure 6 Illustrated is a scenario according to some embodiments in which the UE requests the RRC inactive state as its preferred state after the data inactivity timer expires, and in which the RRC inactive state is also selected by the network as the state to transition to after the data inactivity timer expires.

[0113] As shown, at 602, the UE may initially operate in the RRC inactive state. At 604, the UE may determine to transition to the RRC connected state, and at 606, the UE may initiate a random access channel (RACH) procedure by transmitting a physical RACH (PRACH) preamble (which may also be referred to as MSG1) on the uplink. At 608, the network may respond on the downlink with an uplink grant (which may also be referred to as MSG2). The UE may encode (610) and transmit (612) an RRCConnectionResumeRequest message (which may also be referred to as MSG3) on the uplink, requesting the preferred data inactivity timer value (T1) and the preferred state (RRC_INACTIVE) to transition to when the inactivity timer expires. The network may encode (614) and transmit (616) an RRCConnectionResume message (which may also be referred to as MSG4) on the downlink, indicating the data inactivity period (T2) and the state (RRC_INACTIVE) that the UE is to transition to after the data inactivity timer expires. Note that in Figure 6 the exemplary scenario, the data inactivity timer (e.g., T2 in the illustrated scenario) and state (e.g., RRC_INACTIVE in the illustrated scenario) specified by the network may be bound to the UE.

[0114] Upon completion of the RRC connection establishment procedure, the UE may be in the RRC connected state (618) and may start the data inactivity timer according to the negotiated data inactivity timer length. At 620, the UE may restart the data inactivity timer after each data activity (UL or DL) between the UE and the network. If the timer expires, the UE may transition to the RRC inactive state without any explicit network trigger and may then operate in the RRC inactive state (622).

[0115] Figure 7Illustrated are some embodiments in which the UE requests the RRC idle state as its preferred state after the data inactivity timer expires, and in which the RRC idle state is also selected by the network as the state to transition to after the data inactivity timer expires.

[0116] As shown, at 702, the UE may initially operate in the RRC inactive state. At 704, the UE may determine to transition to the RRC connected state, and at 706, may initiate a RACH procedure by transmitting a PRACH preamble. At 708, the network may respond with an uplink grant. The UE may encode (710) and transmit (712) a RRCConnectionResumeRequest message, requesting a preferred data inactivity timer value (T1) and a preferred state (RRC_IDLE) to transition to when the inactivity timer expires. The network may encode (714) and transmit (716) a RRCConnectionResume message, indicating a data inactivity period (T2) and the state (RRC_IDLE) the UE is to transition to after the data inactivity timer expires. As in the Figure 6 scenario of Figure 7 In an exemplary scenario, the data inactivity timer (e.g., T2 in the illustrated scenario) and state (e.g., RRC_IDLE in the illustrated scenario) specified by the network may be bound to the UE.

[0117] Upon completion of the RRC connection establishment procedure, the UE may be in the RRC connected state (718) and may start the data inactivity timer according to the negotiated data inactivity timer length. At 720, the UE may restart the data inactivity timer after each data activity (UL or DL) between the UE and the network. If the timer expires, the UE may transition to the RRC idle state without any explicit network trigger and may subsequently operate in the RRC idle state (722).

[0118] Figure 8 Illustrated are some embodiments in which the UE requests the RRC inactive state as its preferred state after the data inactivity timer expires, but in which the RRC idle state is not selected by the network as the state to transition to after the data inactivity timer expires.

[0119] As shown, in 802, the UE may initially operate in the RRC inactive state. In 804, the UE may determine to transition to the RRC connected state, and in 806, may initiate a RACH procedure by transmitting a PRACH preamble. In 808, the network may respond with an uplink grant. The UE may encode (810) and transmit (812) a RRCConnectionResumeRequest message, requesting a preferred data inactivity timer value (T1) and a preferred state (RRC_INACTIVE) to transition to when the inactivity timer expires. The network may encode (814) and transmit (816) a RRCConnectionResume message, indicating a data inactivity period (T2) and the state (RRC_IDLE) the UE is to transition to after the data inactivity timer expires. Similarly, in Figure 8 the exemplary scenario of, the data inactivity timer (e.g., T2 in the illustrated scenario) and the state (e.g., RRC_IDLE in the illustrated scenario) specified by the network may be bound to the UE.

[0120] Upon completion of the RRC connection establishment procedure, the UE may be in the RRC connected state (818), and may start a data inactivity timer according to the negotiated data inactivity timer length. In 820, the UE may restart the data inactivity timer after each data activity (UL or DL) between the UE and the network. If the timer expires, the UE may transition to the RRC idle state without any explicit network trigger and may then operate in the RRC idle state (822).

[0121] Figure 9 A scenario is shown in which, according to some embodiments, the UE requests RRC inactivity as its preferred state after the data inactivity timer expires, but in which the network does not indicate a data inactivity period or the state to transition to after the data inactivity timer expires.

[0122] As shown, in 902, the UE may initially operate in the RRC Inactive state. In 904, the UE may determine to transition to the RRC Connected state, and in 906, may initiate a RACH procedure by transmitting a PRACH preamble. In 908, the network may respond with an uplink grant. The UE may encode (910) and transmit (912) a RRCConnectionResumeRequest message, requesting a preferred data inactivity timer value (T1) and a preferred state (RRC_INACTIVE) to transition to when the inactivity timer expires. The network may encode (914) and transmit (916) a RRCConnectionResume message, where the network may not indicate the data inactivity period or the state to transition to after the data inactivity timer expires. For example, this scenario may occur if the network chooses not to support such a feature. In this scenario, the UE may still be able to complete the RRC connection establishment procedure and subsequently operate in the RRC Connected state (918), but may not have a configured data inactivity timer for implicit RRC state transitions or the target RRC state to transition to. Thus, at least according to some embodiments, the UE and the network may use an explicit RRC connection release mechanism to ultimately release the RRC connection in the Figure 9 scenario shown.

[0123] Figure 10 Illustrated is a scenario according to some embodiments where the UE requests the RRC Idle state as its preferred state after the data inactivity timer expires, and where the RRC Idle state is also selected by the network as the state to transition to after the data inactivity timer expires. However, in the Figure 10 scenario, the network may override the use of the negotiated data inactivity timer by providing an explicit RRC connection release message.

[0124] As shown, in 1002, the UE may initially operate in the RRC Inactive state. In 1004, the UE may determine to transition to the RRC Connected state, and in 1006, may initiate a RACH procedure by transmitting a PRACH preamble. In 1008, the network may respond with an uplink grant. The UE may encode (1010) and transmit (1012) a RRCConnectionResumeRequest message, requesting a preferred data inactivity timer value (T1) and a preferred state (RRC_IDLE) to transition to when the inactivity timer expires. The network may encode (1014) and transmit (1016) a RRCConnectionResume message, indicating the data inactivity period (T2) and the state (RRC_IDLE) that the UE is to transition to after the data inactivity timer expires.

[0125] When the RRC connection establishment process is completed, the UE may be in the RRC connected state (1018) and may start a data inactivity timer according to the negotiated data inactivity timer length. At 1020, the UE may restart the data inactivity timer after each data activity (UL or DL) between the UE and the network. If the timer expires, the UE will transition to the RRC idle state without any explicit network trigger and will then operate in the RRC idle state. However, in the illustrated scenario, at 1022, the network may provide an RRCConnectionRelease message indicating that the UE should release the RRC connection and transition to a specified RRC state (e.g., RRC_IDLE in the illustrated scenario) before the data inactivity timer expires, and this RRCConnectionRelease message may also trigger the UE to transition to the RRC idle state (1024).

[0126] Thus, even if an implicit RRC connection release mechanism is configured, the network may still be able to explicitly release the RRC connection (e.g., potentially earlier than the release that would occur according to the implicit RRC connection release mechanism). Note that in such cases, the RRC connection release may configure the UE to transition to a previously agreed-upon RRC state (e.g., RRC_IDLE in the illustrated scenario) or a different RRC state as needed.

[0127] According to at least some embodiments, using the techniques described herein for supporting implicit RRC state transitions and for negotiating the target RRC state to transition to after an RRC connection release may reduce data transmission latency, for example, by potentially leveraging the RRC inactive state. For example, since access stratum context establishment (e.g., including AS security and measurement configuration) may be avoided during a subsequent transition to the RRC connected state, the time required to start data transmission may be reduced (e.g., as a possibility, it may be reduced by 100 ms - 200 ms; other amounts of time for AS context establishment may also be reduced). Additionally, such techniques may reduce the amount of downlink signaling used in a cellular communication system, e.g., reducing at least some RRC connection release signaling that may not be needed. Further, such techniques may allow for a faster transition from the RRC connected state to a higher power efficiency state (such as RRC inactive or RRC idle), e.g., because it may not be necessary to wait for an explicit network protection timer to expire to trigger a state transition from the RRC connected state, which may be beneficial for power-constrained devices for which high power efficiency may be particularly important.

[0128] Figure 11 A scenario is shown in which a UE may indicate a preferred RRC inactive DRX cycle length according to some embodiments.

[0129] As shown, in 1102, the UE may receive system information (e.g., System Information Block 2) from the network, and the system information may indicate the preferred idle DRX value of the network (e.g., T1_IDLE in the shown scenario) and the preferred inactivity DRX value of the network (e.g., T1_INACTIVE in the shown scenario). When in the RRC idle state (1104), the UE may transmit an attachment request or an RNA update request to the network (1106). The attachment / RNA update request may indicate the preferred idle DRX value of the UE (e.g., T2_IDLE in the illustrated scenario), and the preferred inactivity DRX value of the UE (e.g., T2_INACTIVE in the illustrated scenario). In 1108, the network may respond, for example, with an attachment accept message or an RNA update accept message as needed. In 1110, based on the network preferred values and the UE preferred values, the UE may be able to determine and configure its idle and inactivity DRX values. For example, in the illustrated scenario, the idle DRX value may be configured as T3_IDLE = min(T1_IDLE, T2_IDLE), and the inactivity DRX value may be configured as T3_INACTIVE = min(T1_INACTIVE, T2_INACTIVE). In 1112, the UE may transition to the RRC connected state.

[0130] When the UE is released from the RRC connected state, the UE may implement the configured inactivity DRX or idle DRX cycle lengths, e.g., depending on whether the UE is released to RRC inactive or RRC idle. In 1114, for example, as shown, as a first option, the network may transmit an RRCConnectionRelease message having a status indicator equal to inactive, in which case the UE may transition to the RRC inactive state (1116) and perform inactivity DRX monitoring with a period of T3_INACTIVE (1118). In 1120, as a second option, the network may transmit an RRCConnectionRelease message having a status indicator equal to idle, in which case the UE may transition to the RRC idle state (1122) and perform idle DRX monitoring with a period of T3_IDLE (1124). Note that although not shown in Figure 11 the UE may alternatively be implicitly released from the RRC connection (e.g., such as according to the various techniques described herein).

[0131] According to at least some embodiments, using the techniques described herein for negotiating an inactivity DRX cycle length can improve the ability of the network to distinguish between devices in RRC inactive and devices in RRC idle based on different paging cycles and allocate a DRX duration commensurate with the device capabilities / types, which can help the network achieve a more uniform paging load distribution. Additionally, compared to RRC idle, latency-sensitive devices can particularly benefit from the shorter DRX cycle of RRC inactivity, for example, because it can allow for a faster transition to RRC connectedness as needed and when needed.

[0132] In the following, additional exemplary embodiments are provided.

[0133] A set of embodiments may include an apparatus that includes: a processing element configured to cause a wireless device to: establish a radio resource control (RRC) connection with a cellular base station; determine a data inactivity timer length and a target RRC state for an implicit RRC transition; start a data inactivity timer with the determined data inactivity timer length; determine that the data inactivity timer has expired; and transition to the target RRC state at least in part based on determining that the data inactivity timer has expired.

[0134] According to some embodiments, to determine the data inactivity timer length and the target RRC state for an implicit RRC transition, the processing element is further configured to cause the wireless device to: provide an indication of a requested data inactivity timer length and an indication of a preferred target RRC state to the cellular base station; and receive an indication of the data inactivity timer length and the target RRC state from the cellular base station.

[0135] According to some embodiments, the processing element is further configured to cause the wireless device to provide an indication of one or more parameters configured to assist in determining one or more of the data inactivity timer length or the target RRC state, where the one or more parameters include one or more of the following: the device type of the wireless device; the mobility history information of the wireless device; the motion information of the wireless device; or the service mode of the wireless device.

[0136] According to some embodiments, the data inactivity timer length is different from the requested data inactivity timer length.

[0137] According to some embodiments, the target RRC state is different from the preferred target RRC state.

[0138] According to some embodiments, the processing element is further configured to cause the wireless device to: provide an indication of a preferred discontinuous reception (DRX) cycle length for use by the wireless device in the RRC inactive state; and receive from the cellular base station an indication of a DRX cycle length for use by the wireless device in the RRC inactive state.

[0139] According to some embodiments, the processing element is further configured to cause the wireless device to: reset the data inactivity timer after each data activity between the wireless device and the cellular base station.

[0140] According to some embodiments, at least in part based on determining that the data inactivity timer has expired and the transition to the target RRC state includes an implicit RRC state transition, the implicit RRC state transition is performed without explicit signaling between the wireless device and the cellular base station.

[0141] Another set of embodiments may include a wireless device comprising: at least one antenna; radio components operatively coupled to the at least one antenna; and a processing element operatively coupled to the radio components; wherein the wireless device is configured to: transition to a radio resource control (RRC) connected state using a cellular base station; transmit to the cellular base station an indication of a preferred target RRC state to transition to when released from the RRC connected state; receive from the cellular base station an indication of a target RRC state to transition to when released from the RRC connected state; and transition to the target RRC state when released from the RRC connected state.

[0142] According to some embodiments, the wireless device is implicitly released from the RRC connected state at least in part based on a determination of a transition from the RRC connected state made by the wireless device without receiving an explicit indication from the cellular base station.

[0143] According to some embodiments, the wireless device is further configured to: transmit to the cellular base station an indication of a preferred data inactivity timer length for the wireless device; and receive from the cellular base station an indication of a data inactivity timer length for the wireless device, wherein the determination of the transition from the RRC connected state made by the wireless device without receiving an explicit indication from the cellular base station is at least in part based on the expiration of a data inactivity timer having the data inactivity timer length indicated by the cellular base station.

[0144] According to some embodiments, the target RRC state is selected at least in part based on the indication of the preferred target RRC state.

[0145] According to some embodiments, the wireless device releases from the RRC connected state at least in part based on an explicit RRC connection release indication received from the cellular base station.

[0146] According to some embodiments, the target RRC state includes one of the following: RRC idle; or RRC inactive.

[0147] Another set of embodiments may include a cellular base station including: at least one antenna; radio components operatively coupled to the at least one antenna; and a processing element operatively coupled to the radio components; wherein the cellular base station is configured to: establish a radio resource control (RRC) connection with a wireless device; receive an indication from the wireless device of a preferred RRC state to transition to after the RRC connection is released; determine, at least in part based on the indication of the preferred RRC state to transition to after the RRC connection is released, the RRC state that the wireless device is to transition to after the RRC connection is released; and transmit an indication to the wireless device of the determined RRC state that the wireless device is to transition to after the RRC connection is released.

[0148] According to some embodiments, the cellular base station is further configured to: receive an indication from the wireless device of one or more parameters, where the one or more parameters include one or more of the following: the device type of the device; the mobility history information of the wireless device; the motion information of the wireless device; or the service mode of the wireless device, wherein the RRC state that the wireless device is to transition to after the RRC connection is released is further determined at least in part based on the one or more parameters.

[0149] According to some embodiments, the cellular base station is further configured to: receive an indication from the wireless device of a preferred data inactivity timer length for the wireless device; determine, at least in part based on the indication of the preferred data inactivity timer length for the wireless device, the data inactivity timer length for the wireless device; and transmit an indication to the wireless device of the determined data inactivity timer length for the wireless device.

[0150] According to some embodiments, the cellular base station is further configured to: start a data inactivity timer for the wireless device for the RRC connection, where the data inactivity timer has the determined data inactivity timer length; during the RRC connection, use the wireless device to restart the data inactivity timer after each data activity; and when the data inactivity timer expires, implicitly release the RRC connection with the wireless device.

[0151] According to some embodiments, the cellular base station is further configured to: determine not to schedule data activity with the wireless device at the first time, at least in part based on the current value of the data inactivity timer at the first time.

[0152] According to some embodiments, the cellular base station is further configured to: receive an indication from the wireless device of a preferred discontinuous reception (DRX) cycle length for use by the wireless device in the RRC inactive state; determine a DRX cycle length for use by the wireless device in the RRC inactive state, at least in part based on the indication of the preferred DRX cycle length for use by the wireless device in the RRC inactive state; and when the wireless device is in the RRC inactive state, use the determined DRX cycle length for the wireless device.

[0153] Another exemplary embodiment may include a method that includes: performing any or all parts of the foregoing examples by a wireless device.

[0154] Another exemplary embodiment may include a device that includes: an antenna; radio components coupled to the antenna; and a processing element operatively coupled to the radio components, where the device is configured to implement any part or all parts of the foregoing examples.

[0155] Another exemplary embodiment may include a non-transitory computer-accessible memory medium that, when executed at a device, causes the device to implement any part or all parts of any of the foregoing examples.

[0156] Another exemplary embodiment may include a computer program that includes instructions for performing any part or all parts of any of the foregoing examples.

[0157] Another exemplary embodiment may include a device that includes means for performing any element or all elements of any of the foregoing examples.

[0158] Another exemplary embodiment may include an apparatus that includes a processing element configured to cause a wireless device to perform any or all of the elements of any of the foregoing examples.

[0159] As is well known, the use of personally identifiable information should follow privacy policies and practices that are generally recognized as meeting or exceeding industry or government requirements for maintaining user privacy. Specifically, personally identifiable information data should be managed and processed to minimize the risk of inadvertent or unauthorized access or use, and the nature of authorized use should be clearly explained to users.

[0160] Embodiments of the present invention can be implemented in any of a variety of forms. For example, in some embodiments, the present invention can be implemented as a computer-implemented method, a computer-readable memory medium, or a computer system. In other embodiments, the present invention can be implemented using one or more custom-designed hardware devices such as an ASIC. In other embodiments, the present invention can be implemented using one or more programmable hardware elements such as an FPGA.

[0161] In some embodiments, a non-transitory computer-readable memory medium (e.g., a non-transitory memory element) can be configured to store program instructions and / or data, wherein if the program instructions are executed by a computer system, the computer system is caused to perform a method, such as any of the method embodiments described herein, or any combination of the method embodiments described herein, or any subset of any of the method embodiments described herein, or any combination of such subsets.

[0162] In some embodiments, a device (e.g., a UE) can be configured to include a processor (or a set of processors) and a memory medium (or a memory element), wherein the memory medium stores program instructions, wherein the processor is configured to read and execute the program instructions from the memory medium, and wherein the program instructions are executable to implement any one of the various method embodiments described herein (or any combination of the method embodiments described herein, or any subset or any combination of such subsets of any of the method embodiments described herein). The device can be implemented in any of a variety of forms.

[0163] While the above embodiments have been described in considerable detail, many variations and modifications will become apparent to those skilled in the art once the above disclosure is fully understood. The present disclosure is intended that the following claims be interpreted to cover all such variations and modifications.

Claims

1. A wireless device, comprising: at least one antenna; radio components, the radio components being operably coupled to the at least one antenna; and a processor, the processor being operably coupled to the radio components; wherein the wireless device is configured to: transition to a Radio Resource Control (RRC) connected state using a cellular base station; determine to fallback to a preferred RRC state instead of staying in the RRC connected state; transmit, in an RRC message, auxiliary information including the preferred RRC state to the cellular base station, wherein the preferred RRC state is selected from a group including an RRC inactive state and an RRC idle state and is indicated in the auxiliary information, and wherein the auxiliary information indicates that the wireless device determines to fallback to the preferred RRC state instead of staying in the RRC connected state; receive an indication to transition to the preferred RRC state from the cellular base station; and transition to the preferred RRC state.

2. The wireless device according to claim 1, wherein the indication to transition to the preferred RRC state is received in response to transmitting the auxiliary information.

3. The wireless device according to claim 1, wherein the wireless device is further configured to: provide an indication of a preferred Discontinuous Reception (DRX) cycle length for use by the wireless device in the RRC inactive state; and receive an indication of a DRX cycle length for use by the wireless device in the RRC inactive state from the cellular base station.

4. The wireless device according to claim 3, wherein the wireless device is further configured to: transition to the RRC inactive state, wherein the wireless device uses the DRX cycle length when transitioning to the RRC inactive state.

5. The wireless device according to claim 1, wherein the wireless device is further configured to: provide an indication of a preferred Discontinuous Reception (DRX) cycle length for use by the wireless device in the RRC idle state; and receive an indication of a DRX cycle length for use by the wireless device in the RRC idle state from the cellular base station.

6. The wireless device according to claim 5, wherein the wireless device is further configured to: transition to the RRC idle state, wherein the wireless device uses the DRX cycle length when transitioning to the RRC idle state.

7. The wireless device according to claim 1, wherein the wireless device is further configured to: determine a data inactivity timer length for an implicit RRC transition; receive an indication of an RRC state from the cellular base station after transmitting the auxiliary information including the preferred RRC state; start a data inactivity timer with the determined data inactivity timer length; determine that the data inactivity timer has expired; and transition to the RRC state at least in part based on determining that the data inactivity timer has expired.

8. A cellular base station, comprising: at least one antenna; radio components, the radio components being operably coupled to the at least one antenna; and A processing element operably coupled to the radio component; wherein the cellular base station is configured to: Transition a wireless device to a Radio Resource Control (RRC) connected state; Receive, in an RRC message, auxiliary information from the wireless device that includes a preferred RRC state, wherein the preferred RRC state is selected from a group that includes the RRC inactive state and the RRC idle state and is indicated in the auxiliary information, and wherein the auxiliary information indicates that the wireless device determines to fallback to the preferred RRC state instead of remaining in the RRC connected state; Send an indication to the wireless device to transition to the preferred RRC state.

9. The cellular base station according to claim 8, wherein the indication to transition to the preferred RRC state is transmitted in response to receiving the auxiliary information.

10. The cellular base station according to claim 8, wherein the cellular base station is further configured to: Receive an indication from the wireless device of a preferred Discontinuous Reception (DRX) cycle length for use by the wireless device in the RRC inactive state; and Transmit an indication to the wireless device of a DRX cycle length for use by the wireless device in the RRC inactive state.

11. The cellular base station according to claim 10, wherein the cellular base station is further configured to: Transition the wireless device to the RRC inactive state, wherein the cellular base station uses the DRX cycle length when transitioning the wireless device to the RRC inactive state.

12. The cellular base station according to claim 8, wherein the cellular base station is further configured to: Receive an indication from the wireless device of a preferred Discontinuous Reception (DRX) cycle length for use by the wireless device in the RRC idle state; and Transmit an indication to the wireless device of a DRX cycle length for use by the wireless device in the RRC idle state.

13. The cellular base station according to claim 12, wherein the cellular base station is further configured to: Transition the wireless device to the RRC idle state, wherein the cellular base station uses the DRX cycle length when transitioning the wireless device to the RRC idle state.

14. A method for operating a wireless device, the method comprising: Transitioning to a Radio Resource Control (RRC) connected state using a cellular base station; Determining to fallback to a preferred RRC state instead of remaining in the RRC connected state; Transmitting, in an RRC message, auxiliary information to the cellular base station that includes the preferred RRC state, wherein the preferred RRC state is selected from a group that includes the RRC inactive state and the RRC idle state and is indicated in the auxiliary information, and wherein the auxiliary information indicates that the wireless device determines to fallback to the preferred RRC state instead of remaining in the RRC connected state; Receiving an indication from the cellular base station to transition to the preferred RRC state; and Transitioning to the preferred RRC state.

15. The method according to claim 14, wherein the indication to transition to the preferred RRC state is received in response to transmitting the auxiliary information.

16. The method according to claim 14, further comprising: providing an indication of a preferred discontinuous reception (DRX) cycle length for use by the wireless device in the RRC inactive state; and receiving from the cellular base station an indication of a DRX cycle length for use by the wireless device in the RRC inactive state.

17. The method according to claim 16, further comprising: transitioning to the RRC inactive state, wherein the wireless device uses the DRX cycle length when transitioning to the RRC inactive state.

18. The method according to claim 14, further comprising: providing an indication of a preferred discontinuous reception (DRX) cycle length for use by the wireless device in the RRC idle state; and receiving from the cellular base station an indication of a DRX cycle length for use by the wireless device in the RRC idle state.

19. The method according to claim 18, further comprising: transitioning to the RRC idle state, wherein the wireless device uses the DRX cycle length when transitioning to the RRC idle state.

20. The method according to claim 14, further comprising: determining a data inactivity timer length for an implicit RRC transition; after transmitting the auxiliary information including the preferred RRC state, receiving an indication of the RRC state from the cellular base station; starting a data inactivity timer with the determined data inactivity timer length; determining that the data inactivity timer has expired; and transitioning to the RRC state at least in part based on determining that the data inactivity timer has expired.

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