WO2021223055A1

WO2021223055A1 - Self-adaption in wireless network

Info

Publication number: WO2021223055A1
Application number: PCT/CN2020/088580
Authority: WO
Inventors: Fojian ZHANG; Jian Li; Chaofeng HUI; Hao Zhang; Yuankun ZHU; Quanling ZHANG; Bo Yu; Xiuqiu XIA
Original assignee: Qualcomm Incorporated
Priority date: 2020-05-05
Filing date: 2020-05-05
Publication date: 2021-11-11

Abstract

Self-adaptation techniques to recover from packet service call failures due to network limitations in wireless network are disclosed.

Description

SELF-ADAPTION IN WIRELESS NETWORK

TECHNICAL FIELD

Various aspects described herein generally relate to wireless communication systems, and more particularly, to self-adaptation in wireless network.

BACKGROUND

Wireless communication systems have developed through various generations, including a first-generation analog wireless phone service (1G) , a second-generation (2G) digital wireless phone service (including interim 2.5G and 2.75G networks) , a third-generation (3G) high speed data, Internet-capable wireless service and a fourth-generation (4G) service (e.g., Long-Term Evolution (LTE) or WiMax) . There are presently many different types of wireless communication systems in use, including Cellular and Personal Communications Service (PCS) systems. Examples of known cellular systems include the cellular Analog Advanced Mobile Phone System (AMPS) , and digital cellular systems based on Code Division Multiple Access (CDMA) , Frequency Division Multiple Access (FDMA) , Time Division Multiple Access (TDMA) , the Global System for Mobile access (GSM) variation of TDMA, etc.

A fifth generation (5G) mobile standard calls for higher data transfer speeds, greater numbers of connections, and better coverage, among other improvements. The 5G standard, according to the Next Generation Mobile Networks Alliance, is designed to provide data rates of several tens of megabits per second to each of tens of thousands of users, with 1 gigabit per second to tens of workers on an office floor. Several hundreds of thousands of simultaneous connections should be supported in order to support large sensor deployments. Consequently, the spectral efficiency of 5G mobile communications should be significantly enhanced compared to the current 4G standard. Furthermore, signaling efficiencies should be enhanced and latency should be substantially reduced compared to current standards.

5G New Radio (NR) connectivity, or simply NR connectivity, has gained significant commercial traction in recent time. Thus, to attract more users to their network, network operators would like to show NR connectivity to users most of the time on the user interface (UI) of the mobile device such as the user equipment (UE) .

SUMMARY

This summary identifies features of some example aspects, and is not an exclusive or exhaustive description of the disclosed subject matter. Whether features or aspects are included in, or omitted from this summary is not intended as indicative of relative importance of such features. Additional features and aspects are described, and will become apparent to persons skilled in the art upon reading the following detailed description and viewing the drawings that form a part thereof.

An exemplary user equipment (UE) configured to operate in first and second radio access technologies (RATs) is disclosed. The UE may comprise a processor, a memory, and a transceiver. The processor, the memory, and/or the transceiver may be configured to determine whether or not packet service is available from a network while communicating in a standalone (SA) mode with the network via a first network node of the first RAT. The processor, the memory, and/or the transceiver may also be configured to switch from the SA mode to a non-standalone (NSA) mode when it is determined that the packet service is not available from the network. Switching to the NSA mode may include ceasing communication in the SA mode with the network via the first network node. Switching to the NSA mode may also include establishing communication in the NSA mode with the network via a second network of the second RAT. The processor, the memory, and/or the transceiver may further be configured to receive the packet service from the network subsequent to establishing the communication in the NSA mode with the network.

An exemplary method performed by a user equipment (UE) configured to operate in first and second radio access technologies (RATs) is disclosed. The method may comprise determining whether or not packet service is available from a network while communicating in a standalone (SA) mode with the network via a first network node of the first RAT. The method may also comprise switching from the SA mode to a non-standalone (NSA) mode when it is determined that the packet service is not available from the network. Switching to the NSA mode may include ceasing communication in the SA mode with the network via the first network node. Switching to the NSA mode may also include establishing communication in the NSA mode with the network via a second network of the second RAT. The method may further comprise receiving the packet service from the network subsequent to establishing the communication in the NSA mode with the network.

Another exemplary user equipment (UE) configured to operate in first and second radio access technologies (RATs) is disclosed. The UE may comprise means for determining whether or not packet service is available from a network while communicating in a standalone (SA) mode with the network via a first network node of the first RAT. The UE may also comprise means for switching from the SA mode to a non-standalone (NSA) mode when it is determined that the packet service is not available from the network. Switching to the NSA mode may include ceasing communication in the SA mode with the network via the first network node. Switching to the NSA mode may also include establishing communication in the NSA mode with the network via a second network of the second RAT. The UE may further comprise means for receiving the packet service from the network subsequent to establishing the communication in the NSA mode with the network.

A non-transitory computer-readable medium storing computer-executable instructions for a user equipment (UE) configured to operate in first and second radio access technologies (RATs) is disclosed. The executable instructions may comprise one or more instructions instructing the UE to determine whether or not packet service is available from a network while communicating in a standalone (SA) mode with the network via a first network node of the first RAT. The executable instructions may also comprise one or more instructions instructing the UE to switch from the SA mode to a non-standalone (NSA) mode when it is determined that the packet service is not available from the network. Switching to the NSA mode may include ceasing communication in the SA mode with the network via the first network node. Switching to the NSA mode may also include establishing communication in the NSA mode with the network via a second network of the second RAT. The executable instructions may further comprise one or more instructions instructing the UE to receive the packet service from the network subsequent to establishing the communication in the NSA mode with the network.

Other objects and advantages associated with the aspects disclosed herein will be apparent to those skilled in the art based on the accompanying drawings and detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are presented to aid in the description of examples of one or more aspects of the disclosed subject matter and are provided solely for illustration of the examples and not limitation thereof:

FIG. 1 illustrates an exemplary wireless communications system in accordance with one or more aspects of the disclosure;

FIG. 2 is a simplified block diagram of several sample aspects of components that may be employed in wireless communication nodes and configured to support communication in accordance with one or more aspects of the disclosure;

FIG. 3 illustrates a flow of an example scenario that can occur between a user equipment and a 5G network node when there is a packet service call failure;

FIG. 4 illustrates a flow of an example scenario that can occur between a user equipment and network nodes in which the user equipment is able to recover from packet service call failure in accordance with one or more aspects of the disclosure;

FIGs. 5-13 illustrate flow charts of an exemplary self-adaptation method performed by a user equipment to recover from packet service failure while in standalone mode in accordance with one or more aspects of the disclosure;

FIG. 14 illustrates a simplified block diagram of several sample aspects of an apparatus configured for self-adaption in accordance with one or more aspects of the disclosure.

DETAILED DESCRIPTION

Aspects of the subject matter are provided in the following description and related drawings directed to specific examples of the disclosed subject matter. Alternates may be devised without departing from the scope of the disclosed subject matter. Additionally, well-known elements will not be described in detail or will be omitted so as not to obscure the relevant details.

The word “exemplary” is used herein to mean “serving as an example, instance, or illustration. ” Any aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects. Likewise, the term “aspects” does not require that all aspects include the discussed feature, advantage, or mode of operation.

The terminology used herein describes particular aspects only and should not be construed to limit any aspects disclosed herein. As used herein, the singular forms “a, ” “an, ” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. Those skilled in the art will further understand that the terms “comprises, ” “comprising, ” “includes, ” and/or “including, ” as used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

Further, various aspects may be described in terms of sequences of actions to be performed by, for example, elements of a computing device. Those skilled in the art will recognize that various actions described herein can be performed by specific circuits (e.g., an application specific integrated circuit (ASIC) ) , by program instructions being executed by one or more processors, or by a combination of both. Additionally, these sequences of actions described herein can be considered to be embodied entirely within any form of non-transitory computer-readable medium having stored thereon a corresponding set of computer instructions that upon execution would cause an associated processor to perform the functionality described herein. Thus, the various aspects described herein may be embodied in a number of different forms, all of which have been contemplated to be within the scope of the claimed subject matter. In addition, for each of the aspects described herein, the corresponding form of any such aspects may be described herein as, for example, “logic configured to” and/or other structural components configured to perform the described action.

As used herein, the terms “user equipment” (UE) and “base station” are not intended to be specific or otherwise limited to any particular Radio Access Technology (RAT) , unless otherwise noted. In general, such UEs may be any wireless communication device (e.g., a mobile phone, router, tablet computer, laptop computer, tracking device, Internet of Things (IoT) device, etc. ) used by a user to communicate over a wireless communications network. A UE may be mobile or may (e.g., at certain times) be stationary, and may communicate with a Radio Access Network (RAN) . As used herein, the term “UE” may be referred to interchangeably as an “access terminal” or “AT, ” a “client device, ” a “wireless device, ” a “subscriber device, ” a “subscriber terminal, ” a “subscriber station, ” a “user terminal” or UT, a “mobile terminal, ” a “mobile station, ” or variations thereof. Generally, UEs can communicate with a core network via a RAN, and through the core network the UEs can be connected with external networks such as the Internet and with other UEs. Of course, other mechanisms of connecting to the core network and/or the Internet are also possible for the UEs, such as over wired access networks, WiFi networks (e.g., based on Institute of Electrical and Electronics Engineers (IEEE) 802.11, etc. ) and so on.

A base station may operate according to one of several RATs in communication with UEs depending on the network in which it is deployed, and may be alternatively referred to as an Access Point (AP) , a Network Node, a NodeB, an evolved NodeB (eNB) , a general Node B (gNodeB, gNB) , etc. In addition, in some systems a base station may provide edge node signaling functions while in other systems it may provide additional control and/or network management functions.

UEs can be embodied by any of a number of types of devices including but not limited to printed circuit (PC) cards, compact flash devices, external or internal modems, wireless or wireline phones, smartphones, tablets, tracking devices, asset tags, and so on. A communication link through which UEs can send signals to a RAN is called an uplink channel (e.g., a reverse traffic channel, a reverse control channel, an access channel, etc. ) . A communication link through which the RAN can send signals to UEs is called a downlink or forward link channel (e.g., a paging channel, a control channel, a broadcast channel, a forward traffic channel, etc. ) . As used herein the term traffic channel (TCH) can refer to either an uplink /reverse or downlink /forward traffic channel.

FIG. 1 illustrates an exemplary wireless communications system 100 according to one or more aspects. The wireless communications system 100, which may also be referred to as a wireless wide area network (WWAN) , may include various base stations 102 and various UEs 104. The base stations 102 may include macro cells (high power cellular base stations) and/or small cells (low power cellular base stations) . The macro cells may include Evolved NodeBs (eNBs) where the wireless communications system 100 corresponds to an Long-Term Evolution (LTE) network, gNodeBs (gNBs) where the wireless communications system 100 corresponds to a 5G network, and/or a combination thereof, and the small cells may include femtocells, picocells, microcells, etc.

The base stations 102 may collectively form a Radio Access Network (RAN) and interface with an Evolved Packet Core (EPC) or Next Generation Core (NGC) through backhaul links. In addition to other functions, the base stations 102 may perform functions that relate to one or more of transferring user data, radio channel ciphering and deciphering, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity) , inter-cell interference coordination, connection setup and release, load balancing, distribution for non-access stratum (NAS) messages, NAS node selection, synchronization, RAN sharing, multimedia broadcast multicast service (MBMS) , subscriber and equipment trace, RAN information management (RIM) , paging, positioning, and delivery of warning messages. The base stations 102 may communicate with each other directly or indirectly (e.g., through the EPC /NGC) over backhaul links 134, which may be wired or wireless.

The base stations 102 may wirelessly communicate with the UEs 104. Each of the base stations 102 may provide communication coverage for a respective geographic coverage area 110. In an aspect, although not shown in FIG. 1, coverage areas 110 may be subdivided into a plurality of cells (e.g., three) , or sectors, each cell corresponding to a single antenna or array of antennas of a base station 102. As used herein, the term “cell” or “sector” may correspond to one of a plurality of cells of a base station 102, or to the base station 102 itself, depending on the context.

While neighbor macro cell geographic coverage areas 110 may partially overlap (e.g., in a handover region) , some of the geographic coverage areas 110 may be substantially overlapped by a larger geographic coverage area 110. For example, a small cell base station 102' may have a coverage area 110' that substantially overlaps with the coverage area 110 of one or more macro cell base stations 102. A network that includes both small cell and macro cells may be known as a heterogeneous network. A heterogeneous network may also include Home eNBs (HeNBs) and/or Home gNodeBs, which may provide service to a restricted group known as a closed subscriber group (CSG) . The communication links 120 between the base stations 102 and the UEs 104 may include uplink (UL) (also referred to as reverse link) transmissions from a UE 104 to a base station 102 and/or downlink (DL) (also referred to as forward link) transmissions from a base station 102 to a UE 104. The communication links 120 may use multiple input multiple output (MIMO) antenna technology, including spatial multiplexing, beamforming, and/or transmit diversity. The communication links may be through one or more carriers. Allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or less carriers may be allocated for DL than for UL) .

The wireless communications system 100 may further include a wireless local area network (WLAN) access point (AP) 150 in communication with WLAN stations (STAs) 152 via communication links 154 in an unlicensed frequency spectrum (e.g., 5 GHz) . When communicating in an unlicensed frequency spectrum, the WLAN STAs 152 and/or the WLAN AP 150 may perform a clear channel assessment (CCA) prior to communicating in order to determine whether the channel is available.

The small cell base station 102' may operate in a licensed and/or an unlicensed frequency spectrum. When operating in an unlicensed frequency spectrum, the small cell base station 102' may employ LTE or 5G technology and use the same 5 GHz unlicensed frequency spectrum as used by the WLAN AP 150. The small cell base station 102', employing LTE /5G in an unlicensed frequency spectrum, may boost coverage to and/or increase capacity of the access network. LTE in an unlicensed spectrum may be referred to as LTE-unlicensed (LTE-U) , licensed assisted access (LAA) , or MulteFire.

The wireless communications system 100 may further include a mmW base station 180 that may operate in mmW frequencies and/or near mmW frequencies in communication with a UE 182. Extremely high frequency (EHF) is part of the radio frequency (RF) range in the electromagnetic spectrum. EHF has a range of 30 GHz to 300 GHz and a wavelength between 1 millimeter and 10 millimeters. Radio waves in this band may be referred to as a millimeter wave. Near mmW may extend down to a frequency of 3 GHz with a wavelength of 100 millimeters. The super high frequency (SHF) band extends between 3 GHz and 30 GHz, also referred to as centimeter wave. Communications using the mmW/near mmW radio frequency band have high path loss and a relatively short range. The mmW base station 180 may utilize beamforming 184 with the UE 182 to compensate for the extremely high path loss and short range. Further, it will be appreciated that in alternative configurations, one or more base stations 102 may also transmit using mmW or near mmW and beamforming. Accordingly, it will be appreciated that the foregoing illustrations are merely examples and should not be construed to limit the various aspects disclosed herein.

The wireless communications system 100 may further include one or more UEs, such as UE 190, that connects indirectly to one or more communication networks via one or more device-to-device (D2D) peer-to-peer (P2P) links. In the embodiment of FIG. 1, UE 190 has a D2D P2P link 192 with one of the UEs 104 connected to one of the base stations 102 (e.g., through which UE 190 may indirectly obtain cellular connectivity) and a D2D P2P link 194 with WLAN STA 152 connected to the WLAN AP 150 (through which UE 190 may indirectly obtain WLAN-based Internet connectivity) . In an example, the D2D P2P links 192-194 may be supported with any well-known D2D radio access technology (RAT) , such as LTE Direct (LTE-D) , WiFi Direct (WiFi-D) , Bluetooth, and so on. Any of the

base stations

102, 102’, 180 may send measurement requests (e.g., measurement control order (MCO) ) to the

UEs

104, 182, 190, and the UE’s 104, 182, 190 may respond with measurement reports accordingly.

FIG. 2 illustrates several sample components (represented by corresponding blocks) that may be incorporated into an apparatus 202 and an apparatus 204 (corresponding to, for example, a UE and a base station (e.g., eNB, gNB) , respectively, to support the operations as disclosed herein. As an example, the apparatus 202 may correspond to a UE, and the apparatus 204 may correspond to a network node such as a gNB and/or an eNB. It will be appreciated that the components may be implemented in different types of apparatuses in different implementations (e.g., in an ASIC, in a System-on-Chip (SoC) , etc. ) . The illustrated components may also be incorporated into other apparatuses in a communication system. For example, other apparatuses in a system may include components similar to those described to provide similar functionality. Also, a given apparatus may contain one or more of the components. For example, an apparatus may include multiple transceiver components that enable the apparatus to operate on multiple carriers and/or communicate via different technologies.

The apparatus 202 and the apparatus 204 each may include at least one wireless communication device (represented by the communication devices 208 and 214) for communicating with other nodes via at least one designated RAT (e.g., LTE, New Radio (NR) ) . Each communication device 208 may include at least one transmitter (represented by the transmitter 210) for transmitting and encoding signals (e.g., messages, indications, information, and so on) and at least one receiver (represented by the receiver 212) for receiving and decoding signals (e.g., messages, indications, information, pilots, and so on) . Each communication device 214 may include at least one transmitter (represented by the transmitter 216) for transmitting signals (e.g., messages, indications, information, pilots, and so on) and at least one receiver (represented by the receiver 218) for receiving signals (e.g., messages, indications, information, and so on) .

A transmitter and a receiver may comprise an integrated device (e.g., embodied as a transmitter circuit and a receiver circuit of a single communication device) in some implementations, may comprise a separate transmitter device and a separate receiver device in some implementations, or may be embodied in other ways in other implementations. In an aspect, a transmitter may include a plurality of antennas, such as an antenna array, that permits the respective apparatus to perform transmit “beamforming, ” as described further herein. Similarly, a receiver may include a plurality of antennas, such as an antenna array, that permits the respective apparatus to perform receive beamforming, as described further herein. In an aspect, the transmitter and receiver may share the same plurality of antennas, such that the respective apparatus can only receive or transmit at a given time, not both at the same time. A wireless communication device (e.g., one of multiple wireless communication devices) of the apparatus 204 may also comprise a Network Listen Module (NLM) or the like for performing various measurements.

The apparatus 204 may include at least one communication device (represented by the communication device 220) for communicating with other nodes. For example, the communication device 220 may comprise a network interface (e.g., one or more network access ports) configured to communicate with one or more network entities via a wire-based or wireless backhaul connection. In some aspects, the communication device 220 may be implemented as a transceiver configured to support wire-based or wireless signal communication. This communication may involve, for example, sending and receiving messages, parameters, or other types of information. Accordingly, in the example of FIG. 2, the communication device 220 is shown as comprising a transmitter 222 and a receiver 224 (e.g., network access ports for transmitting and receiving) .

The

apparatuses

202 and 204 may also include other components used in conjunction with the operations as disclosed herein. The apparatus 202 may include a processing system 232 for providing functionality relating to, for example, communication with the network. The apparatus 204 may include a processing system 234 for providing functionality relating to, for example, communication with the UEs. In an aspect, the

processing systems

232 and 234 may include, for example, one or more general purpose processors, multi-core processors, ASICs, digital signal processors (DSPs) , field programmable gate arrays (FPGA) , or other programmable logic devices or processing circuitry.

The

apparatuses

202 and 204 may include

measurement components

252 and 254 that may be used to obtain channel related measurements. The measurement component 252 may measure one or more downlink (DL) signals such as channel state information reference signal (CSI-RS) , phase tracking reference signal (PTRS) , primary synchronization signal (PSS) , secondary synchronization signal (SSS) , demodulation reference signal (DMRS) , etc. The measurement component 254 may measure one or more uplink (UL) signals such as DMRS, sounding reference signal (SRS) , etc.

The

apparatuses

202 and 204 may include memory components 238 and 240 (e.g., each including a memory device) , respectively, for maintaining information (e.g., information indicative of reserved resources, thresholds, parameters, and so on) . In various implementations, memory 238 can comprise a computer-readable medium storing one or more computer-executable instructions for a user equipment (UE) where the one or more instructions instruct apparatus 202 (e.g., processing system 232 in combination with communications device 208 and/or other aspects of apparatus 202) to perform any of the functions of FIGs. 3, 4, and 5. In addition, the

apparatuses

202 and 204 may include

user interface devices

244 and 246, respectively, for providing indications (e.g., audible and/or visual indications) to a user and/or for receiving user input (e.g., upon user actuation of a sensing device such a keypad, a touch screen, a microphone, and so on) .

The apparatus 202 may include a timer 256 and a counter. The timer 256 may be configured to measure or otherwise determine one or more time durations. The counter 258 may be configured to count or otherwise determine occurrences of one or more events.

For convenience, the

apparatuses

202 and 204 are shown in FIG. 2 as including various components that may be configured according to the various examples described herein. It will be appreciated, however, that the illustrated blocks may have different functionality in different designs. The components of FIG. 2 may be implemented in various ways. In some implementations, the components of FIG. 2 may be implemented in one or more circuits such as, for example, one or more processors and/or one or more ASICs (which may include one or more processors) . Here, each circuit may use and/or incorporate at least one memory component for storing information or executable code used by the circuit to provide this functionality. For example, some or all of the functionality represented by

blocks

208, 232, 238, and 244 may be implemented by processor and memory component (s) of the apparatus 202 (e.g., by execution of appropriate code and/or by appropriate configuration of processor components) . Similarly, some or all of the functionality represented by

blocks

214, 220, 234, 240, and 246 may be implemented by processor and memory component (s) of the apparatus 204 (e.g., by execution of appropriate code and/or by appropriate configuration of processor components) .

In an aspect, the apparatus 204 may correspond to a “small cell” or a Home gNodeB. The apparatus 202 may transmit and receive messages via a wireless link 260 with the apparatus 204, the messages including information related to various types of communication (e.g., voice, data, multimedia services, associated control signaling, etc. ) . The wireless link 260 may operate over a communication medium of interest, shown by way of example in FIG. 2 as the medium 262, which may be shared with other communications as well as other RATs. A medium of this type may be composed of one or more frequency, time, and/or space communication resources (e.g., encompassing one or more channels across one or more carriers) associated with communication between one or more transmitter /receiver pairs, such as the apparatus 204 and the apparatus 202 for the medium 262.

In general, the apparatus 202 and the apparatus 204 may operate via the wireless link 260 according to one or more radio access types, such as LTE, LTE-U, or NR, depending on the network in which they are deployed. These networks may include, for example, different variants of CDMA networks (e.g., LTE networks, NR networks, etc. ) , TDMA networks, FDMA networks, Orthogonal FDMA (OFDMA) networks, Single-Carrier FDMA (SC-FDMA) networks, and so on.

A UE may be capable of operating in multiple radio access technologies (RATs) . For example, a UE may be capable of operating in a first RAT (e.g., NR) and in a second RAT (e.g., LTE) . These are merely examples, and first and second RATs may be any of the RATs currently known (e.g., WiMax, CDMA, WCDMA, UTRA, Evolved Universal Terrestrial Radio Access (E-UTRA) , GSM, FDMA, GSM, TDMA, etc. ) .

Also, a UE may be may be capable of operating in multiple RATs at the same time. For example, a UE that can operate in both LTE and NR simultaneously is an E-UTRA-NR Dual Connectivity (ENDC) capable UE. Note that ENDC is an example of Multi-RAT DC (MRDC) capability. In general, when an MRDC capable UE is operating in two RATs, it may be communicating with a base station (e.g., eNB) of a first RAT (e.g., LTE) and with a base station (e.g., gNB) of a second RAT (e.g., NR) . When the UE operates in the first RAT, it may communicate with a network node (e.g., base station, gNB, etc. ) of the first RAT. Similarly, when the UE operates in the second RAT, it may communicate with a network node (e.g., base station, eNB, etc. ) of the second RAT.

The UE may be capable of operating in a standalone (SA) or in a non-standalone (NSA) mode within a given RAT. When operating in the SA mode, the UE is able to exchange both control and data plane (also referred to as user plane) information with the network node and/or the core network of the given RAT (e.g., NR) . When operating in the NSA mode, the UE is communicating with network nodes of the first and second RATs. In the NSA mode, the UE can exchange data plane information with the network nodes of both the first RAT (e.g., NR) and the second RAT (e.g., LTE) . However, the control plane information is exchanged only with the network node of the second RAT (e.g., LTE) .

When a UE is registered in a 5G network in the SA mode, a user of the UE may attempt to open up applications/services that require packet services (PS) such as a browser, Twitter ^TM, Facebook ^TM, etc. In some instances, the user may not receive the services due to PS call failures, and the UE may not recover from the failure for a long time.

FIG. 3 illustrates an example flow of a scenario 300 that can occur between a UE and an NR node (e.g., gNB ) operating in 5G SA mode when there is a PS call failure –i.e., when the UE is unable to receive packet service from the network via the NR node. The sequence in scenario 300 is as follows:

1. UE is registered to network in 5G SA;

2. UE sends packet data unit (PDU) session request for data service;

3. Network sends PDU session acceptance;

4. Network sends very quickly sends PDU session release command (cause #36 regular deactivation) causing the UE data call to be terminated;

5. UE responds to complete the release of PDU session;

6. Repeat steps 2-5.

Steps 2-5 can be repeated many times meaning that the packet service is unavailable to the UE for a very long time.

To address such issues, it is proposed to incorporate an automatic recovery mechanism when packet service call failures are encountered. Generally, the proposed automatic recovery mechanism may enable an MRDC UE to recover from PS call failures when in the SA mode by switching to the NSA mode. For example, when the UE discovers that packet service is not available from the network while communicating with the network in the SA mode, the UE may switch from the SA mode to the NSA mode to receive the packet service.

FIG. 4 illustrates an example of a scenario 400 in which the proposed automatic recovery mechanism is incorporated into a UE. In FIG. 4, it is assumed that the UE is multi-RAT capable. For example, in 5G, the UE may be an ENDC UE. The sequence in scenario 400 may be as follows:

A. UE registers to network in 5G SA;

B. While registered in SA mode with 5G NR, UE maintains a counter to record number of PDU session release (e.g., number of #36 regular deactivation) commands received from network (see upper dashed box) :

· UE sends PDU session request to gNB;

· UE receives PDU session accept from gNB;

· UE receives PDU session release command from gNB –counter is incremented;

· UE completes PDU session release;

· Repeat;

C. If the counter reaches MAX COUNT during period T_PDU_REL, conclude packet service is not available from gNB;

D. UE disables SA capability and starts T_backoff_SA timer:

E. UE triggers deregistration from 5G SA mode:

· UE sends deregistration request to gNB;

· UE receives deregistration accept from gNB;

F. UE switches to 5G NSA:

· UE sends attachment request to LTE with ENDC capability indication;

· UE receives attachment accept from gNB;

G. Enhanced packet service (EPS) active;

H. Perform secondary cell group (SCG) procedure to connect to gNB (same or different from gNB of steps A and B) so the UE can get packet service:

I. When T_backoff_SA time expires, UE can switch back to 5G SA:

· UE sends registration request to gNB (same or different from gNB of steps A and B and/or gNB of step H) ;

· UE receives registration accept from gNB.

FIG. 5 illustrates a flow chart of an exemplary self-adaptation method performed by a UE, e.g., to recover from packet service failure while in standalone (SA) mode in accordance with one or more aspects of the disclosure. FIG. 5 may be viewed as a generalization of the flow of FIG. 4. Here, the UE (such as the UE 202) may be capable of operating in multiple radio access technologies (RATs) including first (e.g., 5G NR) and second (e.g., 4G LTE) RATs. The memory component 238 may be viewed as an example of a non-transitory computer-readable medium that stores computer-executable instructions to operate components of the UE 202 such as the transceiver 208 (including transmitter 210 and receiver 212) , the processing system 232 (including one or more processors) , memory component 238, etc.

In block 510, the UE may establish communication in the SA mode with the network via a first network node (e.g., gNB) of the first RAT. For example, the UE may send a registration request to the first network node, and may receive a corresponding registration acceptance from the first network node. Means for performing block 510 may include the processing system 232, the memory component 238 and/or the transceiver 208 of the UE 202.

In block 520, while communicating in the SA mode with the network via the first network node, the UE may determine whether or not packet service (PS) is available from the network. Means for performing block 520 may include the processing system 232, the memory component 238, the timer 256 and/or the counter 258 of the UE 202.

FIG. 6 illustrates a flow chart of an example process that may be performed by the UE to implement block 520. As seen in FIG. 6, the UE may determine that packet service is not available if a count of failures to establish packet session (e.g., packet session establish failure count) within a set time duration (e.g., packet session establish duration) exceeds a set number (e.g., max packet session establish failure count) .

In block 610, the UE may determine a count of packet session establish failures (apacket session establish failure count) over packet session establish duration. Means for performing block 610 may include the processing system 232, the memory component 238, the timer 256 and/or the counter 258 of the UE 202.

FIG. 7 illustrates a flow chart of an example process that may be performed by the UE to implement block 610. As seen in FIG. 7, the UE may count receipt of packet session release command as a failure to establish packet session with the first network node. In block 710, the UE may send a packet session request (e.g., PDU session request) to the first network node (e.g., gNB) in an attempt to establish a packet session (e.g., PDU session) with the network. In block 720, the UE may receive a packet session acceptance (e.g., PDU session accept) from the first network node. Means for performing block 710 and means for performing block 720 may include the processing system 232, the memory component 238 and/or the transceiver 208 of the UE 202.

Subsequently in block 730, the UE may receive a packet session release command corresponding to the sent PDU session request (e.g., #36 regular deactivation command) from the first network node. As indicated, this may be considered as a failure to establish packet session. Thus, in block 740, the UE may increment the packet session establish failure count. Means for performing block 730 may include the processing system 232, the memory component 238 and/or the transceiver 208 of the UE 202. Means for performing block 740 may include the processing system 232, the memory component 238 and/or the counter 258 of the UE 202.

When packet session establish failure is encountered, the UE may repeat attempting to establish the packet session with the network until the packet session establish duration (e.g., T_PDU_REL) passes. Thus, in block 750, the UE may determine whether or not the packet session establish duration has passed. If not (N branch from block 750) , the UE may proceed to block 710. If so (Y branch from block 750) , the UE need not repeat attempting to establish the packet session.

The packet session establish duration (e.g., T_PDU_REL) may be a fixed duration (e.g., 60 sec) , and may start after the UE establishes communication in the SA mode with the network via the first network node (e.g., after block 510) . The packet session establish duration may be preset within the UE. Alternatively or in addition thereto, the packet session establish duration may be set through a configuration message (e.g., radio resource control (RRC) configuration message) from the network.

Referring back to FIG. 6 (after Y branch from block 750) , In block 620, the UE may determine whether or not the count of packet session establish failures over the packet session establish duration is equal to or greater than a max packet session establish failure count. If so (Y branch from block 620) , the UE may determine that the packet service is not available. Otherwise (N branch from block 620) , the UE may determine that the packet service is available. Means for performing block 620 may include the processing system 232 and/or the memory component 238 of the UE 202.

The max packet session establish failure count may be preset within the UE. Alternatively or in addition thereto, the max packet session establish failure count may be set through a configuration message (e.g., radio resource control (RRC) configuration message) from the network.

Referring back to FIG. 5, if it is determined that the packet service is available in the SA mode (Y branch from block 520) , then in block 530, the UE may receive packet services from the network via the first network node. Means for performing block 530 may include the processing system 232, the memory component 238, and/or the transceiver 208 of the UE 202.

On the other hand, if it is determined that the packet service is not available in the SA mode (N branch from block 520) , then in block 540, the UE may switch from the SA mode to the NSA mode. FIG. 8 illustrates a flow chart of an example process that may be performed by the UE to implement block 540. Means for performing block 540 may include the processing system 232, the memory component 238 and/or the transceiver 208 of the UE 202.

In block 810, the UE may cease communication in the SA node with the network via the first network node, and in block 820, the UE may establish communication in the NSA mode with the network via a second network node. The second network node may be a node of the second RAT (e.g., 4G LTE) . When switching from the SA mode to the NSA mode, the UE may notify the second network node that the UE is dual connectivity capable in the first and second RATS (e.g., ENDC capable in 5G NR and 4G LTE) .

FIG. 9 illustrates a flow chart of an example process that may be performed by the UE to implement block 810. In block 910, the UE may send a deregistration request to the first network node. In block 920, the UE may receive a deregistration acceptance corresponding to the deregistration request from the first network node.

FIG. 10 illustrates a flow chart of an example process that may be performed by the UE to implement block 820. In block 1010, the UE may send an attach request to the second network node. In an aspect, the attach request may indicate that the UE is dual connectivity capable (e.g., ENDC capable) . In block 1020, the UE may receive an attach acceptance corresponding to the attach request from the second network node.

Referring back to FIG. 5, subsequent to switching from the SA mode to the NSA mode (e.g., subsequent to establishing communication in the NSA mode with the network via the second network node) , in block 560, the UE may establish a data plane communication with a third network node, which may be a network node of the first RAT. For example, a secondary cell group (SCG) addition procedure may be performed. The third network node may be any network node of the first RAT. That is, in one aspect, the first and third network nodes may be one and the same. But in another aspect, they may be different network nodes. Means for performing block 550 may include the processing system 232, the memory component 238 and/or the transceiver 208 of the UE 202.

In block 560, the UE may receive packet service from the network in the NSA mode. The UE may receive the packet service via the second network node only (e.g., main cell group (MCG) bearer) , via the third network node only (e.g., SCG bearer) , or via both second and third network nodes (e.g., MCG split bearer, SCG split bearer) . Means for performing block 560 may include the processing system 232, the memory component 238 and/or the transceiver 208 of the UE 202.

Subsequent to switching to the NSA mode, in block 570, the UE may switch back to the SA mode. Means for performing block 540 may include the processing system 232, the memory component, the transceiver 208 and/or the timer 256 of the UE 202. FIG. 11 illustrates a flow chart of an example process that may be performed by the UE to implement block 540.

As seen in FIG. 11, the UE may decide to switch back to communicating in the SA mode in the first RAT after spending some time (e.g., SA backoff time) in the NSA mode. The SA backoff time may be preset within the UE. Alternatively or in addition thereto, the SA backoff time may be set through a configuration message (e.g., radio resource control (RRC) configuration message) from the network. In an aspect, the SA backoff time may be started when it is initially determined that the packet service is not available while in the SA mode (e.g., subsequent to block 520) .

In block 1105, the UE may determine whether the SA backoff time has expired or not. If so not (N branch from block 1105) , the UE may loop back. On the other hand, if the SA backoff time has expired (Y branch from block 1105) , then in block 1110, the UE may cease communication in the NSA node with the network via the second network node, and in block 1120, the UE may establish communication in the SA mode with the network via a fourth network node. The fourth network node may be a node of the first RAT (e.g., 5G NR) . The fourth network node can be any network node of the first RAT. That is it may be same as the first network node, or same as the third network node, or different from both the first and third network nodes.

FIG. 12 illustrates a flow chart of an example process that may be performed by the UE to implement block 1110. In block 1210, the UE may send a detach request to the second network node. In block 1220, the UE may receive a detach acceptance corresponding to the detach request from the second network node.

FIG. 13 illustrates a flow chart of an example process that may be performed by the UE to implement block 1120. In block 1310, the UE may send a registration request to the fourth network node. In block 1320, the UE may receive a registration acceptance corresponding to the registration request from the fourth network node.

It should be noted that not all illustrated blocks of FIGs. 5-13 need to be performed, i.e., some blocks may be optional. Also, the numerical references to the blocks in FIGs. 5-13 should not be taken as requiring that the blocks should be performed in a certain order. Indeed, some blocks may be performed concurrently.

FIG. 14 illustrates an example user equipment apparatus 1400 represented as a series of interrelated functional modules connected by a common bus. Each of the modules may be implemented in hardware or as a combination of hardware and software. For example, the modules may be implemented as any combination of the modules of the apparatus 202 of FIG. 2. A module for establishing/ceasing communication in SA mode 1410 may correspond at least in some aspects to a communication device (e.g., communication device 208) , a processing system (e.g., processing system 232) , and/or a memory component (e.g., memory component 238) . A module for establishing/ceasing communication in NSA mode 1420 may correspond at least in some aspects to a communication device (e.g., communication device 208) , a processing system (e.g., processing system 232) , and/or a memory component (e.g., memory component 238) . A module for determining whether packet service is available 1430 may correspond at least in some aspects to a processing system (e.g., processing system 232) , a memory component (e.g., memory component 238) , a timing system (e.g., timer 256) and/or a counting system (e.g., counter 258) . A module for establishing data plane communication may 1440 correspond at least in some aspects to a communication device (e.g., communication device 208) , a processing system (e.g., processing system 232) , a memory component (e.g., memory component 238) , a timing system (e.g., timer 256) and/or a counting system (e.g., counter 258) . A module for receiving packet services 1450 may correspond at least in some aspects to a communication device (e.g., communication device 208) , a processing system (e.g., processing system 232) , a memory component (e.g., memory component 238) , a timing system (e.g., timer 256) and/or a counting system (e.g., counter 258) . A module for switching between SA and NSA modes 1460 may correspond at least in some aspects to a communication device (e.g., communication device 208) , a processing system (e.g., processing system 232) , a memory component (e.g., memory component 238) , a timing system (e.g., timer 256) and/or a counting system (e.g., counter 258) .

The functionality of the modules of FIG. 14 may be implemented in various ways consistent with the teachings herein. In some designs, the functionality of these modules may be implemented as one or more electrical components. In some designs, the functionality of these blocks may be implemented as a processing system including one or more processor components. In some designs, the functionality of these modules may be implemented using, for example, at least a portion of one or more integrated circuits (e.g., an ASIC) . As discussed herein, an integrated circuit may include a processor, software, other related components, or some combination thereof. Thus, the functionality of different modules may be implemented, for example, as different subsets of an integrated circuit, as different subsets of a set of software modules, or a combination thereof. Also, it will be appreciated that a given subset (e.g., of an integrated circuit and/or of a set of software modules) may provide at least a portion of the functionality for more than one module.

In addition, the components and functions represented by FIG. 14, as well as other components and functions described herein, may be implemented using any suitable means. Such means also may be implemented, at least in part, using corresponding structure as taught herein. For example, the components described above in conjunction with the “module for” components of FIG. 14 also may correspond to similarly designated “means for” functionality. Thus, in some aspects one or more of such means may be implemented using one or more of processor components, integrated circuits, or other suitable structure as taught herein.

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

Further, those of skill in the art will appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the aspects disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure.

The various illustrative logical blocks, modules, and circuits described in connection with the aspects disclosed herein may be implemented or performed with a general purpose processor, a DSP, an ASIC, an FPGA, or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

The methods, sequences and/or algorithms described in connection with the aspects disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in random access memory (RAM) , flash memory, read-only memory (ROM) , erasable programmable ROM (EPROM) , electrically erasable programmable ROM (EEPROM) , registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal (e.g., UE) . In the alternative, the processor and the storage medium may reside as discrete components in a user terminal.

In one or more exemplary aspects, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL) , or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk and disc, as used herein, includes compact disc (CD) , laser disc, optical disc, digital versatile disc (DVD) , floppy disk and Blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

While the foregoing disclosure shows illustrative aspects of the disclosure, it should be noted that various changes and modifications could be made herein without departing from the scope of the disclosure as defined by the appended claims. The functions, steps and/or actions of the method claims in accordance with the aspects of the disclosure described herein need not be performed in any particular order. Furthermore, although elements of the disclosure may be described or claimed in the singular, the plural is contemplated unless limitation to the singular is explicitly stated.

Claims

A user equipment (UE) configured to operate in first and second radio access technologies (RATs) , comprising:

a processor;

a memory; and

a transceiver,

wherein the processor, the memory, and/or the transceiver are configured to:

determine whether or not packet service is available from a network while communicating in a standalone (SA) mode with the network via a first network node of the first RAT;

switch from the SA mode to a non-standalone (NSA) mode when it is determined that the packet service is not available from the network by:

ceasing communication in the SA mode with the network via the first network node; and

establishing communication in the NSA mode with the network via a second network of the second RAT; and

receiving the packet service from the network subsequent to establishing the communication in the NSA mode with the network.
The UE of claim 1, wherein the first RAT is 5G New Radio (NR) and the second RAT is 4G Long Term Evolution (LTE) .
The UE of claim 1, wherein when switching from the SA mode to the NSA mode, the processor, the memory, and/or the transceiver are configured to notify that the UE is dual connectivity capable in the first and second RATS.
The UE of claim 1, wherein when determining whether or not the packet service is available from the network while in the SA mode, the processor, the memory, and/or the transceiver are configured to:

determine a count of packet session establish failures over a packet session establish duration, each packet session establish failure count being a failure to establish a packet session with the network via the first network node; and

determine that the packet service is not available when the count of packet session establish failures over the packet session establish duration is equal to or greater than a max packet session establish failure count.
The UE of claim 4, wherein the packet session establish duration and/or the max packet session establish failure count are preset in the UE.
The UE of claim 4, wherein when determining the count of packet session establish failures over the packet session establish duration, the processor, the memory, and/or the transceiver are configured to:

send a PDU session request to the first network node; and

increment the count of packet session establish failures when a PDU session release command corresponding to the sent PDU session request is received from the first network node,

wherein the UE loops through sending the PDU session request and increments the count of packet session establish failures during the packet session establish duration.
The UE of claim 1, wherein when ceasing communication with the network via the first network node, the processor, the memory, and/or the transceiver are configured to:

send a deregistration request to the first network node; and

receive a deregistration acceptance corresponding to the deregistration request from the first network node.
The UE of claim 1, wherein when establishing communication in the NSA mode with the network via the second network node, the processor, the memory, and/or the transceiver are configured to:

send an attach request to the second network node, the attach request indicating that the UE is dual connectivity capable; and

receive an attach acceptance corresponding to the attach request from the second network node.
The UE of claim 8, wherein the attach request indicates that the UE is EUTRA-NR dual connectivity (ENDC) capable.
The UE of claim 1, wherein the processor, the memory, and/or the transceiver are further configured to:

subsequent to switching from the SA mode to the NSA mode, establish a data plane communication with the network via a third network node, the third network node being a network node of the first RAT.
The UE of claim 1, wherein when receiving the packet service from the network, the processor, the memory, and/or the transceiver are configured to:

receive the packet service from the network via the second network node and/or the third network node.
The UE of claim 1, wherein the processor, the memory, and/or the transceiver are further configured to switch back to the SA mode subsequent to switching to the NSA mode by:

ceasing communication in the NSA mode with the network via the second network node; and

establishing communication in the SA mode with the network through a fourth network node, the fourth network node being a network node of the first RAT.
The UE of claim 12, wherein the processor, the memory, and/or the transceiver are configured to switch back to the SA mode after an SA backoff time expires subsequent to determining that the packet service is not available from the network while in the SA mode.
A method of a user equipment (UE) configured to operate in first and second radio access technologies (RATs) , the method comprising:

determining whether or not packet service is available from a network while communicating in a standalone (SA) mode with the network via a first network node of the first RAT;

switching from the SA mode to a non-standalone (NSA) mode when it is determined that the packet service is not available from the network by:

ceasing communication in the SA mode with the network via the first network node; and

establishing communication in the NSA mode with the network via a second network of the second RAT; and

receiving the packet service from the network subsequent to establishing the communication in the NSA mode with the network.
The method of claim 14, wherein the first RAT is 5G New Radio (NR) and the second RAT is 4G Long Term Evolution (LTE) .
The method of claim 14, wherein when switching from the SA mode to the NSA mode, the network is notified that the UE is dual connectivity capable in the first and second RATS.
The method of claim 14, wherein determining whether or not the packet service is available from the network while in the SA mode comprises:

determining a count of packet session establish failures over a packet session establish duration, each packet session establish failure count being a failure to establish a packet session with the network via the first network node; and

determining that the packet service is not available when the count of packet session establish failures over the packet session establish duration is equal to or greater than a max packet session establish failure count.
The method of claim 17, wherein the packet session establish duration and/or the max packet session establish failure count are preset in the UE.
The method of claim 17, wherein determining the count of packet session establish failures over the packet session establish duration comprises:

sending a packet data unit (PDU) session request for the packet service to the first network node; and

incrementing the count of packet session establish failures when a PDU session release command corresponding to the sent PDU session request is received from the first network node,

wherein the UE loops through sending the PDU session request, and incrementing the count of packet session establish failures during the packet session establish duration.
The method of claim 14, wherein ceasing communication with the network via the first network node comprises:

sending a deregistration request to the first network node; and

receiving a deregistration acceptance corresponding to the deregistration request from the first network node.
The method of claim 14, wherein establishing communication in the NSA mode with the network via the second network node comprises:

sending an attach request to the second network node, the attach request indicating that the UE is dual connectivity capable; and

receiving an attach acceptance corresponding to the attach request from the second network node.
The method of claim 21, wherein the attach request indicates that the UE is EUTRA-NR dual connectivity (ENDC) capable.
The method of claim 14, further comprising:

subsequent to establishing communication in the NSA mode with the network via the second network node, establishing a data plane communication with the network via a third network node, the third network node being a network node of the first RAT, and the third network node being the first network node or a network different from the first network node.
The method of claim 23, wherein receiving the packet service from the network comprises:

receiving the packet service from the network via the second network node and/or the third network node.
The method of claim 14, further comprising:

switching back to the SA mode subsequent to switching to the NSA mode by:

ceasing communication in the NSA mode with the network via the second network node; and

establishing communication in the SA mode with the network through the first network node or through another network node of the first RAT.
The method of claim 25, wherein switching back to the SA mode is performed after an SA backoff time expires subsequent to determining that the packet service is not available from the network while in the SA mode.
A user equipment (UE) configured to operate in first and second radio access technologies (RATs) , comprising:

means for determining whether or not packet service is available from a network while communicating in a standalone (SA) mode with the network via a first network node of the first RAT;

means for switching from the SA mode to a non-standalone (NSA) mode when it is determined that the packet service is not available from the network, wherein the means for switching:

ceases communication in the SA mode with the network via the first network node; and

establishes communication in the NSA mode with the network via a second network of the second RAT; and

means for receiving the packet service from the network subsequent to establishing the communication in the NSA mode with the network.
The UE of claim 27, further comprising:

means for switching back to SA mode after being in the NSA mode for an SA backoff time, wherein the means for switching back:

cease communication in the NSA mode with the network via the second network node; and

establish communication in the SA mode with the network through the first network node or through another network node of the first RAT.
A non-transitory computer-readable medium storing computer-executable instructions for a user equipment (UE) configured to operate in first and second radio access technologies (RATs) , the computer-executable instructions comprising:

one or more instructions instructing the UE to determine whether or not packet service is available from a network while communicating in a standalone (SA) mode with the network via a first network node of the first RAT;

one or more instructions instructing the UE to switch from the SA mode to a non-standalone (NSA) mode when it is determined that the packet service is not available from the network by:

ceasing communication in the SA mode with the network via the first network node; and

establishing communication in the NSA mode with the network via a second network of the second RAT; and

one or more instructions instructing the UE to receive the packet service from the network subsequent to establishing the communication in the NSA mode with the network.
The non-transitory computer-readable medium of claim 29, further comprising:

one or more instructions instructing the UE to switch back to the SA mode after being in the NSA mode for an SA backoff time by:

ceasing communication in the NSA mode with the network via the second network node; and

establishing communication in the SA mode with the network through the first network node or through another network node of the first RAT.