WO2022033102A1

WO2022033102A1 - Method and user equipment for returning to new radio after inter-system fallback

Info

Publication number: WO2022033102A1
Application number: PCT/CN2021/094638
Authority: WO
Inventors: Xin Xu; Yongsheng Shi
Original assignee: Guangdong Oppo Mobile Telecommunications Corp Ltd
Current assignee: Guangdong Oppo Mobile Telecommunications Corp Ltd
Priority date: 2020-08-10
Filing date: 2021-05-19
Publication date: 2022-02-17
Anticipated expiration: 2023-02-10

Abstract

A user equipment (UE) executes a method for returning to new radio (NR) after inter-system fallback. The UE performs a call that undergoes inter-system fallback from a high generation radio access technology (RAT) system to a low generation RAT system. The UE determines whether to return to an NR system upon termination of the call. The UE is prevented from returning to the NR system when at least one non-NR preferred condition is fulfilled and returns to the NR system when determining to return to a 5G cell, and the at least one non-NR preferred condition is not fulfilled. The method allows a UE to return to the 5G NR system in the idle mode of 2G, 3G, or 4G after the inter-system fallback. The UE may perform background 5G cell search in the idle mode of 2G, 3G, or 4G and determine whether to return to 5G or not.

Description

METHOD AND USER EQUIPMENT FOR RETURNING TO NEW RADIO AFTER INTER-SYSTEM FALLBACK

Technical Field

The present disclosure relates to the field of communication systems, and more particularly, to a method and user equipment (UE) for returning to new radio (NR) after inter-system fallback.

Background Art

Wireless communication systems, such as the third-generation (3G) of mobile telephone standards and technology are well known. Such 3G standards and technology have been developed by the Third Generation Partnership Project (3GPP) . The 3rd generation of wireless communications has generally been developed to support macro-cell mobile phone communications. Communication systems and networks have developed towards being a broadband and mobile system. In cellular wireless communication systems, user equipment (UE) is connected by a wireless link to a radio access network (RAN) . The RAN comprises a set of base stations (BSs) which provide wireless links to the UEs located in cells covered by the base station, and an interface to a core network (CN) which provides overall network control. As will be appreciated the RAN and CN each conduct respective functions in relation to the overall network. The 3rd Generation Partnership Project has developed the so-called Long Term Evolution (LTE) system, namely, an Evolved Universal Mobile Telecommunication System Territorial Radio Access Network, (E-UTRAN) , for a mobile access network where one or more macro-cells are supported by a base station known as an eNodeB or eNB (evolved NodeB) . More recently, LTE is evolving further towards the so-called 5G or NR (new radio) systems where one or more cells are supported by a base station known as a gNB.

Technical Problem

In a cellular network of non-standalone architecture (NSA) comprising 4G LTE and 5G systems, evolved packet system (EPS) Fallback can be an initial solution for voice call before Voice over NR (VoNR) . When a UE undergoes EPS fallback to a LTE system to perform an Internet protocol (IP) multimedia subsystem (IMS) voice call, two scenarios may occur:

After a voice call ends in LTE, the UE may stay in LTE if the network does not redirect the UE back to 5G NR or an LTE cell does not provide a list of 5G neighbor frequencies or cells in a system information block (SIB) .

If a voice call setup fails in LTE, the UE can fall back to a lower generation system, such as a 3G or 2G system, and retry the call in the lower generation system in a circuit switch (CS) domain. After the voice call ends in the 3G or 2G system, the UE goes back to an idle state. As no specification defines reselection between 2G/3G and 5G, the UE can only reselect to 4G first. The UE may then reselect from 4G to 5G.

At least two problems are left after in these scenarios. One problem is that no specification defines whether the UE should stay on 4G LTE or try to go back to 5G after the voice call. If the UE needs to go back to 5G, how can the UE re-select to 5G as soon as possible is a second problem.

Technical Solution

An object of the present disclosure is to propose a method and a wireless device, such as a UE, for returning to new radio (NR) after inter-system fallback.

In a first aspect, an embodiment of the invention provides a method for returning to new radio (NR) after inter-system fallback, executable in a user equipment (UE) , comprising:

performing a call that undergoes inter-system fallback from a high generation radio access technology (RAT) system to a low generation RAT system;

determining whether to return to an NR system upon termination of the call;

preventing from returning to the NR system when at least one non-NR preferred condition is fulfilled; and returning to the NR system when determining to return to a 5G cell, and the at least one non-NR preferred condition is not fulfilled.

In a second aspect, an embodiment of the invention provides a method for returning to new radio (NR) after inter-system fallback, executable in a user equipment (UE) , comprising:

performing 5G cell search between two paging occasions in an idle mode of the UE in a non-NR system after termination of the call; and

returning to an NR system when determining a 5G cell obtained in the 5G cell search for camping.

In a third aspect, an embodiment of the invention provides a user equipment (UE) comprising a transceiver and a processor. The processor is connected to the transceiver and configured to execute the following steps: performing a call that undergoes inter-system fallback from a high generation radio access technology (RAT) system to a low generation RAT system;

determining whether to return to an NR system upon termination of the call;

In a fourth aspect, an embodiment of the invention provides a user equipment (UE) comprising a transceiver and a processor. The processor is connected to the transceiver and configured to execute the following steps: performing a call that undergoes inter-system fallback from a high generation radio access technology (RAT) system to a low generation RAT system;

The disclosed method may be implemented in a chip. The chip may include a processor, configured to call and run a computer program stored in a memory, to cause a device in which the chip is installed to execute the disclosed method.

The disclosed method may be programmed as computer executable instructions stored in non-transitory computer-readable medium. The non-transitory computer readable medium, when loaded to a computer, directs a processor of the computer to execute the disclosed method.

The non-transitory computer-readable medium may comprise at least one from a group consisting of: a hard disk, a CD-ROM, an optical storage device, a magnetic storage device, a read only memory, a programmable read only memory, an erasable programmable read only memory, EPROM, an electrically erasable programmable read only memory and a flash memory.

The disclosed method may be programmed as computer program product, that causes a computer to execute the disclosed method.

The disclosed method may be programmed as a computer program, that causes a computer to execute the disclosed method.

Advantageous Effects

According to current 3GPP standards, a UE can return to 5G from a 4G LTE connected mode. How to return to the 5G NR system in the idle mode of 2G, 3G, or 4G is an issue. No mechanism has been defined to determine whether or not the UE should return to the 5G NR system after the inter-system fallback. Embodiments of the invention provide a method for a UE to return to the 5G NR system in the idle mode of 2G, 3G, or 4G after the inter-system fallback.

Description of Drawings

In order to more clearly illustrate the embodiments of the present disclosure or related art, the following figures will be described in the embodiments are briefly introduced. It is obvious that the drawings are merely some embodiments of the present disclosure, a person having ordinary skill in this field can obtain other figures according to these figures without paying the premise.

FIG. 1 illustrates a schematic view of a telecommunication system.

FIG. 2 illustrates a schematic view showing a method of returning to NR after inter-system fallback according to an embodiment of the invention.

FIG. 3 illustrates a schematic view showing an embodiment of the method of returning to NR after inter-system fallback with one non-NR preferred condition.

FIG. 4 illustrates a schematic view showing an embodiment of the method of returning to NR after inter-system fallback with one bandwidth-related non-NR preferred condition.

FIG. 5 illustrates a schematic view showing an embodiment of the method of returning to NR after inter-system fallback with one battery-related non-NR preferred condition.

FIG. 6 illustrates a schematic view showing an embodiment of the method of returning to NR after inter-system fallback with a plurality of non-NR preferred conditions.

FIG. 7 illustrates a schematic view showing an embodiment of the method of returning to NR after inter-system fallback using background 5G cell search.

FIG. 8 illustrates a schematic view showing an example of background 5G cell search.

FIG. 9 illustrates a schematic view showing 5G cells contained in assistant information for 5G cell search.

FIG. 10 illustrates a schematic view showing an embodiment of the method of returning to NR after inter-system fallback using background 5G cell search with increasing intervals.

FIG. 11 illustrates a schematic view showing an embodiment of the method of returning to NR after inter-system fallback that suppresses low generation radio access technologies (RATs) .

FIG. 12 illustrates a schematic view showing a system for wireless communication according to an embodiment of the present disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the disclosure are described in detail with the technical matters, structural features, achieved objects, and effects with reference to the accompanying drawings as follows. Specifically, the terminologies in the embodiments of the present disclosure are merely for describing the purpose of the certain embodiment, but not to limit the disclosure.

With reference to FIG. 1, a telecommunication system including a UE 10a, a UE 10b, a base station (BS) 200a, and a network entity device 300 executes the disclosed method according to an embodiment of the present disclosure. FIG. 1 is shown for illustrative not limiting, and the system may comprise more UEs, BSs, and CN entities. Connections between devices and device components are shown as lines and arrows in the FIGs. The UE 10a may include a processor 11a, a memory 12a, and a transceiver 13a. The UE 10b may include a processor 11b, a memory 12b, and a transceiver 13b. The base station 200a may include a processor 201a, a memory 202a, and a transceiver 203a. The network entity device 300 may include a processor 301, a memory 302, and a transceiver 303. Each of the

processors

11a, 11b, 201a, and 301 may be configured to implement proposed functions, procedures and/or methods described in the description. Layers of radio interface protocol may be implemented in the

processors

11a, 11b, 201a, and 301. Each of the

memory

12a, 12b, 202a, and 302 operatively stores a variety of programs and information to operate a connected processor. Each of the

transceivers

13a, 13b, 203a, and 303 is operatively coupled with a connected processor, transmits and/or receives radio signals or wireline signals. The UE 10a may be in communication with the UE 10b through a sidelink. The base station 200a may be an eNB, a gNB, or one of other types of radio nodes, and may configure radio resources for the UE 10a and UE 10b.

Each of the

processors

11a, 11b, 201a, and 301 may include application-specific integrated circuits (ASICs) , other chipsets, logic circuits and/or data processing devices. Each of the

memory

12a, 12b, 202a, and 302 may include read-only memory (ROM) , a random access memory (RAM) , a flash memory, a memory card, a storage medium and/or other storage devices. Each of the

transceivers

13a, 13b, 203a, and 303 may include baseband circuitry and radio frequency (RF) circuitry to process radio frequency signals. When the embodiments are implemented in software, the techniques described herein can be implemented with modules, procedures, functions, entities and so on, that perform the functions described herein. The modules can be stored in a memory and executed by the processors. The memory can be implemented within a processor or external to the processor, in which those can be communicatively coupled to the processor via various means are known in the art.

The network entity device 300 may be a node in a CN. CN may include 2G, 3G, or 4G LTE CN or 5G core (5GC) which includes user plane function (UPF) , session management function (SMF) , mobility management function (AMF) , unified data management (UDM) , policy control function (PCF) , control plane (CP) /user plane (UP) separation (CUPS) , authentication server (AUSF) , network slice selection function (NSSF) , and the network exposure function (NEF) .

An example of the UE in the description may include one of the UE 10a or UE 10b. An example of the base station in the description may include the base station 200a. Uplink (UL) transmission of a control signal or data may be a transmission operation from a UE to a base station. Downlink (DL) transmission of a control signal or data may be a transmission operation from a base station to a UE.

An example showing the steps that the UE may take to return 5G after a voice call ends in 2G/3G is detailed in the following:

1. The UE is camped on a 5G standalone architecture (SA) cell and registered with an IMS.

2. The User makes an IMS voice call and the network redirects the UE from NR to LTE in an EPS fallback.

3. When experiencing a failure in the IMS voice call in LTE, such as SERVICE_UNAVAILABLE (503) , and the UE falls back to 3G to retry the voice call in the CS domain.

4. When the voice call is successfully initiated in 3G and terminated, the network releases the UE to an idle state.

5. The UE may reselect from 3G to 4G LTE according to a cell reselection procedure defined in the 3GPP standards.

6. The UE needs to trigger tracking area update (TAU) procedure in LTE to notify the network.

7. If the UE has an uplink (UL) or downlink (DL) data call, the UE will stay in LTE to complete the data call and not return to 5G.

8. After the data call, the UE may reselect from LTE to 5G according to the cell reselection procedure defined in the 3GPP specifications.

Embodiments of the invention provide a solution to determine whether the UE should stay on 4G or return to 5G, and also provide a solution of fast return to 5G after EPS fallback and the voice call. Embodiments of the invention also provide a method for a UE to return to the 5G NR system in the idle mode of 2G, 3G, or 4G after the inter-system fallback. Embodiments of the invention may apply for the UE with the voice call ending in LTE.

With reference to FIG. 2, in an embodiment of the invention, the UE executes a method for returning to new radio (NR) after inter-system fallback. The UE performs a call that undergoes inter-system fallback from a high generation radio access technology (RAT) system to a low generation RAT system (block 220) . For example, the inter-system fallback may comprise fallback from a 5G NR system to a 4G LTE system, from a 4G LTE system to a 3G universal mobile telecommunication system (UMTS) , and/or from a 3G UMTS to a 2G global system for mobile communication (GSM) system.

The UE determines whether to return to an NR system upon termination of the call (block 222) . In an embodiment, the NR system may comprise at least a 5G cell. Alternatively, the NR system may comprise a 5G cell and a 5GC. The UE is prevented from returning to the NR system when at least one non-NR preferred condition is fulfilled (block 224) . The UE returns to the NR system when determining to return to a 5G cell, and the at least one non-NR preferred condition is not fulfilled (block 226) . The at least one non-NR preferred condition may comprise a condition reflects preference related to radio resources or hardware resources associated with the UE.

Conditions for return to NR or not:

In an embodiment of the invention, if the 4G system bandwidth is larger than 5G system bandwidth, the UE does not initiate fast return to 5G, unless the network re-directs the UE back to 5G. Normally, 5G NR system provides greater bandwidth that promise higher data throughput, and, therefore, the UE prefers to stay on the 5G NR system. However, many operators have 5G operations on low band and small bandwidth compared to their 4G deployment. In this case, it does not make sense to let the UE return to the 5G NR system. The system bandwidth is static information that the UE can obtain and use to perform the determination in

blocks

222, 224, and 226. When bandwidth of the NR system is less than bandwidth of the LTE system, the UE may choose to stay in the 4G LTE system.

In an embodiment of the invention, if the UE is in low-battery state, the UE does not initiate a fast return to the 5G NR system, unless the network re-directs the UE to return to the 5G NR system. Currently, UE power consumption in a 5G NR system is still much higher than in a 4G LTE system. When the UE is in a low-battery state, the UE may choose to stay in the 4G LTE system to save power.

The determination in block 222 as to whether to return to an NR system upon termination of the call may comprise more steps involving network configuration, user configuration, and the at least one non-NR preferred condition.

With reference to FIG. 3, an embodiment of the disclosed method is detailed in the following. In an embodiment of the invention, the UE executes a method for returning to NR after inter-system fallback. The UE performs a call that undergoes inter-system fallback from a high generation radio access technology (RAT) system to a low generation RAT system (block 220) . For example, the inter-system fallback may comprise fallback from a 5G NR system to a 4G LTE system, from a 4G LTE system to a 3G universal mobile telecommunication system (UMTS) , and/or from a 3G UMTS to a 2G global system for mobile communication (GSM) system.

The UE terminates the call when a session of the call is completed (block 221) . The UE determines whether to return to an NR system upon termination of the call (block 222) . In an embodiment, the NR system may comprise at least a 5G cell. Alternatively, the NR system may comprise a 5G cell and a 5GC. The operation in block 222 further comprises the following procedures. The UE determines whether to return to an NR system upon termination of the call according to configuration (block 2221) . The configuration may comprise either one or both of network configuration from the network and user configuration that is set and stored in the UE.

When the UE determines not to return to an NR system upon termination of the call according to the configuration, the method ends. When determining to return to an NR system upon termination of the call according to the configuration, the UE performs 5G cell search (block 2222) and determines whether to return to an NR system upon termination of the call according to a result of the 5G cell search (block 2223) . The UE may perform 5G cell search in a connected mode or background 5G cell search between two paging occasions in an idle mode of the UE in a non-NR system after termination of the call. The UE may increase an interval between two rounds of 5G cell search so that an interval of two current two rounds of 5G cell search is greater than an interval of two previous two rounds of 5G cell search before the current two rounds of 5G cell search.

When determining not to return to an NR system upon termination of the call according to the result of the 5G cell search (block 2223) , the UE continues 5G cell search (block 22223) . When determining to return to an NR system upon termination of the call according to the result of the 5G cell search, the UE determines whether at least one non-NR preferred condition is fulfilled (block 2224) .

The UE is prevented from returning to the NR system when at least one non-NR preferred condition is fulfilled (block 224) . The UE returns to the NR system when determining to return to a 5G cell, and the at least one non-NR preferred condition is not fulfilled (block 226) . Note that the UE may have more non-NR preferred conditions.

With reference to FIG. 4, for example, the non-NR preferred condition is related to a bandwidth of the NR system and a bandwidth of a non-NR system. When the bandwidth of the NR system is less than the bandwidth of a non-NR system (block 224-1) , the UE is prevented from returning to the NR system (block 224-2) .

With reference to FIG. 5, for example, the non-NR preferred condition is related to a battery life of the UE and a battery life threshold. When the UE is in a low-battery state in which the battery life of the UE is less than the battery life threshold (block 224-3) , the UE is prevented from returning to the NR system (block 224-4) .

With reference to FIG. 6, an embodiment of the disclosed method with more non-NR preferred conditions is detailed in the following. In an embodiment of the invention, the UE executes a method for returning to NR after inter-system fallback. The UE performs a call that undergoes inter-system fallback from a high generation radio access technology (RAT) system to a low generation RAT system (block 220) . For example, the inter-system fallback may comprise fallback from a 5G NR system to a 4G LTE system, from a 4G LTE system to a 3G universal mobile telecommunication system (UMTS) , and/or from a 3G UMTS to a 2G global system for mobile communication (GSM) system.

When the UE determines not to return to an NR system upon termination of the call according to the configuration, the method ends. When determining to return to an NR system upon termination of the call according to the configuration, the UE performs 5G cell search (block 2222) and determines whether to return to an NR system upon termination of the call according to a result of the 5G cell search (block 2223) .

When determining not to return to an NR system upon termination of the call according to the result of the 5G cell search (block 2223) , the UE continues 5G cell search (block 2222) . When determining to return to an NR system upon termination of the call according to the result of the 5G cell search, the UE determines whether at least one of a plurality of non-NR preferred conditions is fulfilled (block 2224a) .

The UE is prevented from returning to the NR system when at least one of the non-NR preferred conditions is fulfilled (block 224a) . The UE returns to the NR system when determining to return to a 5G cell, and none of the non-NR preferred conditions is fulfilled (block 226a) .

Background 5G cell search:

In an embodiment of the invention, if the UE determines to return to 5G as soon as possible and the network does not re-direct the UE back to 5G or the network does not provide 5G neighbor frequency list in a system information block (SIB) , the UE may perform the following operations in 4G idle state.

The UE may perform background 5G cell search during 4G discontinuous reception (DRX) cycle, i.e. between paging occasions in the 4G LTE system.

In an embodiment of the invention, the UE performs its own 5G frequency/cell search while in service of the 4G LTE system. Once detecting a 5G cell, the UE uses the 5G cell in the cell reselection procedure to return to the 5G NR system.

With reference to FIG. 7 and FIG. 8, an embodiment of the disclosed method with background 5G cell search is detailed in the following. In an embodiment of the invention, the UE, such as UE 10, executes a method for returning to NR after inter-system fallback. The UE performs a call that undergoes inter-system fallback from a high generation radio access technology (RAT) system to a low generation RAT system (block 310) . For example, the inter-system fallback may comprise fallback from a 5G NR system to a 4G LTE system, from a 4G LTE system to a 3G universal mobile telecommunication system (UMTS) , and/or from a 3G UMTS to a 2G global system for mobile communication (GSM) system.

The UE performs 5G cell search, such as 512, 514, and 516, between two paging occasions in an idle mode of the UE in a non-NR system after termination of the call (block 312) and returns to the NR system when determining a 5G cell obtained in the 5G cell search for camping (block 314) . The non-NR system may comprise a global system for mobile communication (GSM) , a universal mobile telecommunication system (UMTS) , or a long term evolution (LTE) system. With reference to FIG. 8, for example,

non-NR paging

411, 413, 415, and 417 to the UE in the non-NR system may comprise LTE paging. The UE performs 5G cell search 512 between paging occasions of

non-NR paging

411 and 413, 5G cell search 514 between paging occasions of

non-NR paging

413 and 415, and 5G cell search 516 between paging occasions of

non-NR paging

415 and 417.

The UE may use assistant information to perform the 5G cell search, and the assistant information comprises:

a previously camped 5G cell prior to the inter-system fallback;

a 5G neighbor cell adjacent to the previously camped 5G cell;

a stored historical 5G cell; or

a configured NR measurement object comprising a 5G frequency.

With reference to FIG. 9, a UE 10 in 5G cell C1, LTE cell C8, 3G cell C9, and 2G cell C10. A 5G NR system 405 is connected to 5G base stations operating 5G cells, such as C1-C7. A 4G LTE system 404 is connected to 4G base stations operating 4G cells, such as C8. A 3G system 403 is connected to 3G base stations operating 3G cells, such as C9. A 2G system 402 is connected to 2G base stations operating 2G cells, such as C10.

In an embodiment of the invention, to assist background 5G cell search, the UE may use the assistant information in 5G cell search, determine whether a 5G cell in the assistant information is a qualified cell, and obtain the qualified cell as the cell for returning to the NR system and camping as stated in block 314. The UE may use the previously camped 5G cell, such as C1, prior to the inter-system fallback for 5G cell search if the UE has not moved from coverage of the previously camped 5G cell. The UE may use the 5G neighbor cell/frequency, such as one or more of C2, C3, and C4, of the previously camped 5G cell prior to the inter-system fallback. The UE may use the stored 5G cell/frequency, such as one or more of C5, C6, and C7, based on UE history. The UE may use the configured NR measurement object which contains 5G cell/frequency from 4G network, if any. Accordingly, the UE may use relevant prior knowledge of the assistant information to hasten 5G cell search.

In an embodiment of the invention, the UE may use a telescoping timer to control the 5G background search. The background cell search may consume power of the UE. It is possible that the UE may in a location with no neighbor 5G cell. Therefore, the UE may gradually increase the interval of each round of 5G cell search.

With reference to FIG. 10, the UE performs 5G cell search between two paging occasions in an idle mode of the UE in a non-NR system after termination of the call (block 312-1) . The UE increases an interval between two rounds of 5G cell search so that an interval of two current two rounds of 5G cell search is greater than an interval of two previous two rounds of 5G cell search before the current two rounds of 5G cell search (block 312-2) . For example, the UE waits for 1 minute between the 1st round and the 2nd round of 5G cell search, then waits for 2 mins between the 2nd round and the 3rd round of 5G cell search, and waits for 4 mins between the 3rd round and the 4th round of 5G cell search. The operation in blocks 31 may comprise operations in blocks 312-1 and 312-2.

The following embodiments may be applied to the UE with the voice call ended in 2G/3G.

With reference to FIG. 11, an embodiment of the disclosed method with a voice call ended in a low generation RAT system is detailed in the following. In an embodiment of the invention, the UE executes a method for returning to NR after inter-system fallback. The UE performs a call that undergoes inter-system fallback from a high generation radio access technology (RAT) system to a low generation RAT system (block 320) . For example, the inter-system fallback may comprise fallback from a 5G NR system to a 4G LTE system, from a 4G LTE system to a 3G universal mobile telecommunication system (UMTS) , and/or from a 3G UMTS to a 2G global system for mobile communication (GSM) system.

When the voice call ended in the low generation RAT system, such as 2G or 3G systems (block 322) , the UE may suppress initiation of a new call in the low generation RAT system to facilitate a quick return to the high generation RAT system (block 324) . The high generation RAT system comprises the NR system or a long term evolution (LTE) system. The low generation RAT system comprises a global system for mobile communication (GSM) or a universal mobile telecommunication system (UMTS) . In an embodiment of the invention, after the voice call ends in 3G/2G, the UE may suppress user UL data call and abort DL data call on 3G/2G to allow the UE to perform 4G/5G cell search. The embodiment of the invention limits activities of the UE on 2G and 3G. In most network deployment, 4G deployment should be already sufficient to allow the UE to quickly find a 4G cell. After returning to 4G, the UE can use the aforementioned embodiments of the disclosed method to determine whether to return to 5G. An embodiment of the invention may apply the background 5G cell search to the UE in the 2G or 3G network. If the UE cannot reselect and return to 4G quickly, the background 5G search gives the UE another opportunity to return to 5G.

FIG. 12 is a block diagram of an example system 700 for wireless communication according to an embodiment of the present disclosure. Embodiments described herein may be implemented into the system using any suitably configured hardware and/or software. FIG. 12 illustrates the system 700 including a radio frequency (RF) circuitry 710, a baseband circuitry 720, a processing unit 730, a memory/storage 740, a display 750, a camera 760, a sensor 770, and an input/output (I/O) interface 780, coupled with each other as illustrated.

The processing unit 730 may include circuitry, such as, but not limited to, one or more single-core or multi-core processors. The processors may include any combinations of general-purpose processors and dedicated processors, such as graphics processors and application processors. The processors may be coupled with the memory/storage and configured to execute instructions stored in the memory/storage to enable various applications and/or operating systems running on the system.

The baseband circuitry 720 may include circuitry, such as, but not limited to, one or more single-core or multi-core processors. The processors may include a baseband processor. The baseband circuitry may handle various radio control functions that enable communication with one or more radio networks via the RF circuitry. The radio control functions may include, but are not limited to, signal modulation, encoding, decoding, radio frequency shifting, etc. In some embodiments, the baseband circuitry may provide for communication compatible with one or more radio technologies. For example, in some embodiments, the baseband circuitry may support communication with 5G NR, LTE, an evolved universal terrestrial radio access network (EUTRAN) and/or other wireless metropolitan area networks (WMAN) , a wireless local area network (WLAN) , a wireless personal area network (WPAN) . Embodiments in which the baseband circuitry is configured to support radio communications of more than one wireless protocol may be referred to as multi-mode baseband circuitry. In various embodiments, the baseband circuitry 720 may include circuitry to operate with signals that are not strictly considered as being in a baseband frequency. For example, in some embodiments, baseband circuitry may include circuitry to operate with signals having an intermediate frequency, which is between a baseband frequency and a radio frequency.

The RF circuitry 710 may enable communication with wireless networks using modulated electromagnetic radiation through a non-solid medium. In various embodiments, the RF circuitry may include switches, filters, amplifiers, etc. to facilitate the communication with the wireless network. In various embodiments, the RF circuitry 710 may include circuitry to operate with signals that are not strictly considered as being in a radio frequency. For example, in some embodiments, RF circuitry may include circuitry to operate with signals having an intermediate frequency, which is between a baseband frequency and a radio frequency.

In various embodiments, the transmitter circuitry, control circuitry, or receiver circuitry discussed above with respect to the UE, eNB, or gNB may be embodied in whole or in part in one or more of the RF circuitries, the baseband circuitry, and/or the processing unit. As used herein, “circuitry” may refer to, be part of, or include an Application Specific Integrated Circuit (ASIC) , an electronic circuit, a processor (shared, dedicated, or group) , and/or memory (shared, dedicated, or group) that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable hardware components that provide the described functionality. In some embodiments, the electronic device circuitry may be implemented in, or functions associated with the circuitry may be implemented by, one or more software or firmware modules. In some embodiments, some or all of the constituent components of the baseband circuitry, the processing unit, and/or the memory/storage may be implemented together on a system on a chip (SOC) .

The memory/storage 740 may be used to load and store data and/or instructions, for example, for the system. The memory/storage for one embodiment may include any combination of suitable volatile memory, such as dynamic random access memory (DRAM) ) , and/or non-volatile memory, such as flash memory. In various embodiments, the I/O interface 780 may include one or more user interfaces designed to enable user interaction with the system and/or peripheral component interfaces designed to enable peripheral component interaction with the system. User interfaces may include, but are not limited to a physical keyboard or keypad, a touchpad, a speaker, a microphone, etc. Peripheral component interfaces may include, but are not limited to, a non-volatile memory port, a universal serial bus (USB) port, an audio jack, and a power supply interface.

In various embodiments, the sensor 770 may include one or more sensing devices to determine environmental conditions and/or location information related to the system. In some embodiments, the sensors may include, but are not limited to, a gyro sensor, an accelerometer, a proximity sensor, an ambient light sensor, and a positioning unit. The positioning unit may also be part of, or interact with, the baseband circuitry and/or RF circuitry to communicate with components of a positioning network, e.g., a global positioning system (GPS) satellite. In various embodiments, the display 750 may include a display, such as a liquid crystal display and a touch screen display. In various embodiments, the system 700 may be a mobile computing device such as, but not limited to, a laptop computing device, a tablet computing device, a netbook, an ultrabook, a smartphone, etc. In various embodiments, the system may have more or less components, and/or different architectures. Where appropriate, the methods described herein may be implemented as a computer program. The computer program may be stored on a storage medium, such as a non-transitory storage medium.

The embodiment of the present disclosure is a combination of techniques/processes that can be adopted in 3GPP specification to create an end product.

A person having ordinary skill in the art understands that each of the units, algorithm, and steps described and disclosed in the embodiments of the present disclosure are realized using electronic hardware or combinations of software for computers and electronic hardware. Whether the functions run in hardware or software depends on the condition of application and design requirement for a technical plan. A person having ordinary skill in the art can use different ways to realize the function for each specific application while such realizations should not go beyond the scope of the present disclosure. It is understood by a person having ordinary skill in the art that he/she can refer to the working processes of the system, device, and unit in the above-mentioned embodiment since the working processes of the above-mentioned system, device, and unit are basically the same. For easy description and simplicity, these working processes will not be detailed.

It is understood that the disclosed system, device, and method in the embodiments of the present disclosure can be realized in other ways. The above-mentioned embodiments are exemplary only. The division of the units is merely based on logical functions while other divisions exist in realization. It is possible that a plurality of units or components are combined or integrated into another system. It is also possible that some characteristics are omitted or skipped. On the other hand, the displayed or discussed mutual coupling, direct coupling, or communicative coupling operate through some ports, devices, or units whether indirectly or communicatively by ways of electrical, mechanical, or other kinds of forms.

The units as separating components for explanation are or are not physically separated. The units for display are or are not physical units, that is, located in one place or distributed on a plurality of network units. Some or all of the units are used according to the purposes of the embodiments. Moreover, each of the functional units in each of the embodiments can be integrated into one processing unit, physically independent, or integrated into one processing unit with two or more than two units.

If the software function unit is realized and used and sold as a product, it can be stored in a readable storage medium in a computer. Based on this understanding, the technical plan proposed by the present disclosure can be essentially or partially realized as the form of a software product. Or, one part of the technical plan beneficial to the conventional technology can be realized as the form of a software product. The software product in the computer is stored in a storage medium, including a plurality of commands for a computational device (such as a personal computer, a server, or a network device) to run all or some of the steps disclosed by the embodiments of the present disclosure. The storage medium includes a USB disk, a mobile hard disk, a read-only memory (ROM) , a random access memory (RAM) , a floppy disk, or other kinds of media capable of storing program codes.

According to current 3GPP standards, a UE can return to 5G from a 4G LTE connected mode. How to return to the 5G NR system in the idle mode of 2G, 3G, or 4G is an issue. No mechanism has been defined to determine whether or not the UE should return to the 5G NR system after the inter-system fallback. Embodiments of the invention provide a method for a UE to return to the 5G NR system in the idle mode of 2G, 3G, or 4G after the inter-system fallback. The UE may perform background 5G cell search in the idle mode of 2G, 3G, or 4G and determine whether to return to 5G or not.

While the present disclosure has been described in connection with what is considered the most practical and preferred embodiments, it is understood that the present disclosure is not limited to the disclosed embodiments but is intended to cover various arrangements made without departing from the scope of the broadest interpretation of the appended claims.

Claims

A method for returning to new radio (NR) after inter-system fallback, executable in a user equipment (UE) , comprising:

performing a call that undergoes inter-system fallback from a high generation radio access technology (RAT) system to a low generation RAT system;

determining whether to return to an NR system upon termination of the call;

preventing from returning to the NR system when at least one non-NR preferred condition is fulfilled; and

returning to the NR system when determining to return to a 5G cell, and the at least one non-NR preferred condition is not fulfilled.
The method for returning to new radio after inter-system fallback of claim 1, wherein the non-NR preferred condition is related to a bandwidth of the NR system and a bandwidth of a non-NR system, and the preventing from returning to the NR system further comprises:

preventing from returning to the NR system when the bandwidth of the NR system is less than the bandwidth of the non-NR system.
The method for returning to new radio after inter-system fallback of claim 1, wherein the non-NR preferred condition is related to a battery life of the UE and a battery life threshold, and the preventing from returning to the NR system further comprises:

preventing from returning to the NR system when the UE is in a low-battery state in which the battery life of the UE is less than the battery life threshold.
The method for returning to new radio after inter-system fallback of claim 1, further comprising:

performing 5G cell search between two paging occasions in an idle mode of the UE in a non-NR system after termination of the call.
The method for returning to new radio after inter-system fallback of claim 4, further comprising:

increasing an interval between two rounds of 5G cell search so that an interval of two current two rounds of 5G cell search is greater than an interval of two previous two rounds of 5G cell search before the current two rounds of 5G cell search.
The method for returning to new radio after inter-system fallback of claim 4, wherein the UE uses assistant information to perform the 5G cell search, and the assistant information comprises:

a previously camped 5G cell prior to the inter-system fallback;

a 5G neighbor cell adjacent to the previously camped 5G cell;

a stored historical 5G cell; or

a configured NR measurement object comprising a 5G frequency.
The method for returning to new radio after inter-system fallback of claim 4, wherein the non-NR system comprises a global system for mobile communication (GSM) , a universal mobile telecommunication system (UMTS) , or a long term evolution (LTE) system.
The method for returning to new radio after inter-system fallback of claim 1, further comprising:

suppressing initiation of a new call in the low generation RAT system to facilitate quick return to the high generation RAT system.
The method for returning to new radio after inter-system fallback of claim 8, wherein the high generation RAT system comprises the NR system or a long term evolution (LTE) system, and the low generation RAT system comprises a global system for mobile communication (GSM) or a universal mobile telecommunication system (UMTS) .
A method for returning to new radio (NR) after inter-system fallback, executable in a user equipment (UE) , comprising:

performing a call that undergoes inter-system fallback from a high generation radio access technology (RAT) system to a low generation RAT system;

performing 5G cell search between two paging occasions in an idle mode of the UE in a non-NR system after termination of the call; and

returning to an NR system when determining a 5G cell obtained in the 5G cell search for camping.
The method for returning to new radio after inter-system fallback of claim 10, further comprising:

preventing from returning to the NR system when bandwidth of the NR system is less than bandwidth of the non-NR system.
The method for returning to new radio after inter-system fallback of claim 10, further comprising:

preventing from returning to the NR system when the UE is in a low-battery state in which a battery life of the UE is less than a battery life threshold.
The method for returning to new radio after inter-system fallback of claim 10, further comprising:

increasing an interval between two rounds of 5G cell search so that an interval of two current two rounds of 5G cell search is greater than an interval of two previous two rounds of 5G cell search before the current two rounds of 5G cell search.
The method for returning to new radio after inter-system fallback of claim 10, wherein the UE uses assistant information to perform the 5G cell search, and the assistant information comprises:

a previously camped 5G cell prior to the inter-system fallback;

a 5G neighbor cell adjacent to the previously camped 5G cell;

a stored historical 5G cell; or

a configured NR measurement object comprising a 5G frequency.
The method for returning to new radio after inter-system fallback of claim 10, wherein the non-NR system comprises a global system for mobile communication (GSM) , a universal mobile telecommunication system (UMTS) , or a long term evolution (LTE) system.
The method for returning to new radio after inter-system fallback of claim 10, further comprising:

suppressing initiation of a new call in the low generation RAT system to facilitate quick return to the high generation RAT system.
The method for returning to new radio after inter-system fallback of claim 16, wherein the high generation RAT system comprises the NR system or a long term evolution (LTE) system, and the low generation RAT system comprises a global system for mobile communication (GSM) or a universal mobile telecommunication system (UMTS) .
A user equipment (UE) , comprising:

a transceiver; and

a processor connected to the transceiver and configured to execute steps of:

performing a call that undergoes inter-system fallback from a high generation radio access technology (RAT) system to a low generation RAT system;

determining whether to return to an NR system upon termination of the call;

preventing from returning to the NR system when at least one non-NR preferred condition is fulfilled; and

returning to the NR system when determining to return to a 5G cell, and the at least one non-NR preferred condition is not fulfilled.
The user equipment of claim 18, wherein the non-NR preferred condition is related to a bandwidth of the NR system and a bandwidth of a non-NR system, and the preventing from returning to the NR system further comprises:

preventing from returning to the NR system when the bandwidth of the NR system is less than the bandwidth of the non-NR system.
The user equipment of claim 18, wherein the non-NR preferred condition is related to a battery life of the UE and a battery life threshold, and the preventing from returning to the NR system further comprises:

preventing from returning to the NR system when the UE is in a low-battery state in which the battery life of the UE is less than the battery life threshold.
The user equipment of claim 18, wherein the processor is further configured to execute:

performing 5G cell search between two paging occasions in an idle mode of the UE in a non-NR system after termination of the call.
The user equipment of claim 21, wherein the processor is further configured to execute:

increasing an interval between two rounds of 5G cell search so that an interval of two current two rounds of 5G cell search is greater than an interval of two previous two rounds of 5G cell search before the current two rounds of 5G cell search.
The user equipment of claim 21, wherein the UE uses assistant information to perform the 5G cell search, and the assistant information comprises:

a previously camped 5G cell prior to the inter-system fallback;

a 5G neighbor cell adjacent to the previously camped 5G cell;

a stored historical 5G cell; or

a configured NR measurement object comprising a 5G frequency.
The user equipment of claim 21, wherein the non-NR system comprises a global system for mobile communication (GSM) , a universal mobile telecommunication system (UMTS) , or a long term evolution (LTE) system.
The user equipment of claim 18, wherein the processor is further configured to execute:

suppressing initiation of a new call in the low generation RAT system to facilitate a quick return to the high generation RAT system.
The user equipment of claim 25, wherein the high generation RAT system comprises the NR system or a long term evolution (LTE) system, and the low generation RAT system comprises a global system for mobile communication (GSM) or a universal mobile telecommunication system (UMTS) .
A user equipment (UE) , comprising:

a transceiver; and

a processor connected to the transceiver and configured to execute steps of:

performing a call that undergoes inter-system fallback from a high generation radio access technology (RAT) system to a low generation RAT system;

performing 5G cell search between two paging occasions in an idle mode of the UE in a non-NR system after termination of the call; and

returning to an NR system when determining a 5G cell obtained in the 5G cell search for camping.
The user equipment of claim 27, wherein the processor is further configured to execute:

preventing from returning to the NR system when bandwidth of the NR system is less than bandwidth of the non-NR system.
The user equipment of claim 27, wherein the processor is further configured to execute:

preventing from returning to the NR system when the UE is in a low-battery state in which a battery life of the UE is less than a battery life threshold.
The user equipment of claim 27, wherein the processor is further configured to execute:

increasing an interval between two rounds of 5G cell search so that an interval of two current two rounds of 5G cell search is greater than an interval of two previous two rounds of 5G cell search before the current two rounds of 5G cell search.
The user equipment of claim 27, wherein the UE uses assistant information to perform the 5G cell search, and the assistant information comprises:

a previously camped 5G cell prior to the inter-system fallback;

a 5G neighbor cell adjacent to the previously camped 5G cell;

a stored historical 5G cell; or

a configured NR measurement object comprising a 5G frequency.
The user equipment of claim 27, wherein the non-NR system comprises a global system for mobile communication (GSM) , a universal mobile telecommunication system (UMTS) , or a long term evolution (LTE) system.
The user equipment of claim 27, wherein the processor is further configured to execute:

suppressing initiation of a new call in the low generation RAT system to facilitate a quick return to the high generation RAT system.
The user equipment of claim 33, wherein the high generation RAT system comprises the NR system or a long term evolution (LTE) system, and the low generation RAT system comprises a global system for mobile communication (GSM) or a universal mobile telecommunication system (UMTS) .
A chip, comprising:

a processor, configured to call and run a computer program stored in a memory, to cause a device in which the chip is installed to execute any of the methods of claims 1 to 9.
A chip, comprising:

a processor, configured to call and run a computer program stored in a memory, to cause a device in which the chip is installed to execute any of the methods of claims 10 to 17.
A computer readable storage medium, in which a computer program is stored, wherein the computer program causes a computer to execute any of the methods of claims 1 to 9.
A computer readable storage medium, in which a computer program is stored, wherein the computer program causes a computer to execute any of the methods of claims 10 to 17.
A computer program product, comprising a computer program, wherein the computer program causes a computer to execute any of the methods of claims 1 to 9.
A computer program product, comprising a computer program, wherein the computer program causes a computer to execute any of the methods of claims 10 to 17.
A computer program, wherein the computer program causes a computer to execute any of the methods of claims 1 to 9.
A computer program, wherein the computer program causes a computer to execute any of the methods of claims 10 to 17.