Radio access technology switching based on network support

Abstract

Methods, systems, and devices for wireless communication are described. Generally, the described techniques provide efficient fallback from one RAT to another while maximizing the services available to the UE. When a UE's request to communicate with a base station using one RAT is rejected by the network node for unexpected reasons, the UE can use the techniques described herein to fall back to the appropriate RAT. For example, after receiving a response indicating that a request including fifth-generation (5G) parameters has been rejected, the UE can discard the 5G parameters and fall back to fourth-generation (4G) instead of second-generation (2G) or third-generation (3G). Unexpected reasons can be pre-configured and determined based on several factors, including the UE's subscription, the Public Land Mobile Network (PLMN) associated with the network node, etc.

Description

Technical Field

[0001] The following relates generally to wireless communications, and more particularly to network-supported radio access technology (RAT) switching.

[0002] background

[0003] Wireless communication systems are widely deployed to provide various types of communication content, such as voice, video, packet data, messaging, broadcast, etc. These systems may be able to support communication with multiple users by sharing available system resources (e.g., time, frequency, and power). Examples of such multiple access systems include fourth generation (4G) systems (such as long term evolution (LTE) systems, advanced LTE (LTE-A) systems, or LTE-A Pro systems), and fifth generation (5G) systems, which may be referred to as new radio (NR) systems. These systems may employ various technologies, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal frequency division multiple access (OFDMA), or discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-S-OFDM).

[0004] A wireless multiple access communication system may include one or more base stations or one or more network access nodes, each base station or network access node simultaneously supporting communication of multiple communication devices, which may be further referred to as user equipment (UE). In some wireless communication systems, a UE may support multiple RATs for communicating with one or more base stations. For example, in addition to the second generation (2G) and the third generation (3G), a UE may also support 5G and 4G for communication with one or more base stations. Improved techniques for identifying a suitable RAT for communication with a base station at a UE may be desirable.

[0005] Overview

[0006] The described technology relates to improved methods, systems, devices and apparatuses for supporting radio access technology (RAT) selection and communication (e.g., attachment and bearer setup) based on network support. In general, the described technology provides efficient selection of RAT (e.g., fallback from one RAT to another RAT) while maximizing the services available to the UE. When a request from a UE to communicate with a base station using one RAT is rejected by a network node for unexpected reasons, the UE can use the technology described herein to select an appropriate RAT. For example, after receiving a response indicating that a request including fifth generation (5G) parameters is rejected, the UE may discard the 5G parameters and fall back to or maintain a connection using a fourth generation (4G) RAT instead of falling back to a second generation (2G) or third generation (3G) RAT. Unexpected reasons may be preconfigured and may be determined based on several factors, including the UE's subscription, a public land mobile network (PLMN) associated with the network node, etc. Further, unexpected reasons may include reasons for which the handling at the UE is not defined.

[0007] A method of wireless communication supporting a first radio access technology and a second radio access technology at a UE is described. The method may include: establishing a connection with a base station according to the first radio access technology; transmitting a first request associated with a bearer for a communication service to a first network node via the connection established with the base station, the first request including parameters associated with the second radio access technology; receiving a response from the first network node indicating that the first request is rejected, the response including a rejection cause that is one of a preconfigured cause in a set of preconfigured causes; determining that the second radio access technology is not supported by the first network node for communication with the UE based on the rejection cause being one of the preconfigured causes in the set of preconfigured causes; and transmitting a second request associated with a bearer for the communication service to the first network node based on the determination, the second request not including parameters associated with the second radio access technology.

[0008] An apparatus for supporting wireless communication of a first radio access technology and a second radio access technology at a UE is described. The apparatus may include a processor, a memory coupled to the processor (e.g., operatively, communicatively, functionally, electronically, electrically, etc.), and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to: establish a connection with a base station according to the first radio access technology; transmit a first request associated with a bearer for a communication service to a first network node via the connection established with the base station, the first request including parameters associated with the second radio access technology; receive a response from the first network node indicating that the first request is rejected, the response including a rejection cause that is one of a preconfigured cause set; determine that the second radio access technology is not supported by the first network node for communication with the UE based on the rejection cause being one of the preconfigured causes in the preconfigured cause set; and transmit a second request associated with a bearer for a communication service to the first network node based on the determination, the second request not including parameters associated with the second radio access technology.

[0009] Another apparatus for wireless communication supporting a first radio access technology and a second radio access technology at a UE is described. The apparatus may include means for: establishing a connection with a base station according to the first radio access technology; transmitting a first request associated with a bearer for a communication service to a first network node via the connection established with the base station, the first request including parameters associated with the second radio access technology; receiving a response from the first network node indicating that the first request is rejected, the response including a rejection cause that is one of a preconfigured cause in a set of preconfigured causes; determining that the second radio access technology is not supported by the first network node for communication with the UE based on the rejection cause being one of the preconfigured causes in the set of preconfigured causes; and transmitting a second request associated with a bearer for a communication service to the first network node based on the determination, the second request not including parameters associated with the second radio access technology.

[0010] A non-transitory computer-readable medium storing code for wireless communication at a UE supporting a first radio access technology and a second radio access technology is described. The code may include instructions executable by a processor to perform the following operations: establish a connection with a base station according to the first radio access technology; transmit a first request associated with a bearer for a communication service to a first network node via the connection established with the base station, the first request including parameters associated with the second radio access technology; receive a response from the first network node indicating that the first request is rejected, the response including a rejection cause that is one of a preconfigured cause in a set of preconfigured causes; determine that the second radio access technology is not supported by the first network node for communication with the UE based on the rejection cause being one of the preconfigured causes in the set of preconfigured causes; and transmit a second request associated with a bearer for the communication service to the first network node based on the determination, the second request not including parameters associated with the second radio access technology.

[0011] Some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein may further include operations, features, devices, or instructions for the following actions: adding a PLMN associated with the first network node to a list of PLMNs that may not be supported by the second radio access technology; and based on adding the PLMN to the list, suppressing the transmission of a request including parameters associated with the second radio access technology to the network node associated with the PLMN. Some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein may further include operations, features, devices, or instructions for the following actions: receiving a threshold number of responses from the first network node, each response including a rejection cause that may be one of a preconfigured cause set; and based on receiving the threshold number of responses, transmitting a second request to the first network node, the second request not including parameters associated with the second radio access technology. Some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein may further include operations, features, devices, or instructions for the following actions: receiving an indication of a threshold number of responses after which the UE may transmit a second request.

[0012] Some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein may further include operations, features, devices, or instructions for the following actions: determining that the second radio access technology is not supported by the first network node based on the UE's subscription to an operator having a relationship with the PLMN associated with the first network node. In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the preconfigured cause includes a rejection cause for which the handling at the UE may not be defined. In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the preconfigured cause includes one or more of a first cause indicating that the base station may not be able to derive the identity of the UE, a second cause indicating that an evolved packet system (EPS) service may not be allowed in the PLMN associated with the first network node, and a third cause indicating a protocol error. In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the first request and the second request include an attach request or a tracking area update request.

[0013] A method of wireless communication supporting a first radio access technology and a second radio access technology at a UE is described. The method may include: establishing a first connection with a first base station according to the second radio access technology; transmitting a first request associated with a bearer for a communication service to a first network node via the first connection with the first base station, the first request including parameters associated with the second radio access technology; receiving a response from the first base station indicating that the first request is rejected, the response including a rejection cause that is one of a preconfigured cause set of preconfigured causes; determining that the second radio access technology is not supported by the first network node for communication with the UE based on the rejection cause being one of the preconfigured causes in the preconfigured cause set; establishing a second connection with the first base station or the second base station according to the first radio access technology based on the determination; and transmitting a second request associated with a bearer for a communication service to the first network node or the second network node via the second connection with the first base station or the second base station based on the determination, the second request not including parameters associated with the second radio access technology.

[0014] An apparatus for supporting wireless communication of a first radio access technology and a second radio access technology at a UE is described. The apparatus may include a processor, a memory coupled to the processor (e.g., operatively, communicatively, functionally, electronically, electrically, etc.), and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to: establish a first connection with a first base station according to the second radio access technology; transmit a first request associated with a bearer for a communication service to a first network node via the first connection with the first base station, the first request including parameters associated with the second radio access technology; receive a response from the first base station indicating that the first request is rejected, the response including a rejection cause that is one of a preconfigured cause set; determine that the second radio access technology is not supported by the first network node for communication with the UE based on the rejection cause being one of the preconfigured causes in the preconfigured cause set; establish a second connection with the first base station or the second base station according to the first radio access technology based on the determination; and transmit a second request associated with a bearer for a communication service to the first network node or the second network node via the second connection with the first base station or the second base station based on the determination, the second request not including parameters associated with the second radio access technology.

[0015] Another apparatus for wireless communication supporting a first radio access technology and a second radio access technology at a UE is described. The apparatus may include means for: establishing a first connection with a first base station according to the second radio access technology; transmitting a first request associated with a bearer for a communication service to a first network node via the first connection with the first base station, the first request including parameters associated with the second radio access technology; receiving a response from the first base station indicating that the first request was rejected, the response including a rejection cause that is one of a preconfigured cause set of preconfigured causes; determining that the second radio access technology is not supported by the first network node for communication with the UE based on the rejection cause being one of the preconfigured causes in the preconfigured cause set; establishing a second connection with the first base station or the second base station according to the first radio access technology based on the determination; and transmitting a second request associated with a bearer for a communication service to the first network node or the second network node via the second connection with the first base station or the second base station based on the determination, the second request not including parameters associated with the second radio access technology.

[0016] A non-transitory computer-readable medium storing code for wireless communication at a UE supporting a first radio access technology and a second radio access technology is described. The code may include instructions executable by a processor to perform the following operations: establish a first connection with a first base station according to the second radio access technology; transmit a first request associated with a bearer for a communication service to a first network node via the first connection with the first base station, the first request including parameters associated with the second radio access technology; receive a response from the first base station indicating that the first request is rejected, the response including a rejection cause that is one of a preconfigured cause in a set of preconfigured causes; determine that the second radio access technology is not supported by the first network node for communication with the UE based on the rejection cause being one of the preconfigured causes in the set of preconfigured causes; establish a second connection with the first base station or the second base station according to the first radio access technology based on the determination; and transmit a second request associated with a bearer for a communication service to the first network node or the second network node via the second connection with the first base station or the second base station based on the determination, the second request not including parameters associated with the second radio access technology.

[0017] Some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein may further include operations, features, devices, or instructions for the following actions: adding a PLMN associated with the first network node to a list of PLMNs that are not supported by the second radio access technology; and based on adding the PLMN to the list, suppressing the transmission of a request including parameters associated with the second radio access technology to the network node associated with the PLMN. Some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein may further include operations, features, devices, or instructions for the following actions: receiving a threshold number of responses from the first network node, each response including a rejection cause that may be one of a preconfigured cause set; and based on receiving the threshold number of responses, transmitting a second request to the first network node or the second network node, the second request including parameters associated with the first radio access technology. Some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein may further include operations, features, devices, or instructions for the following actions: receiving an indication of a threshold number of responses after which the UE may transmit a second request.

[0018] In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, it is determined that the second radio access technology may not be supported by the first network node based on the UE's subscription to an operator having a relationship with a PLMN associated with the first network node. In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the preconfigured cause includes a rejection cause for which the handling at the UE may not be defined. In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the preconfigured cause includes one or more of a first cause indicating that the base station may not be able to derive the identity of the UE, a second cause indicating that an evolved packet system (EPS) service may not be allowed in the PLMN associated with the first network node, and a third cause indicating a protocol error. In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the first request and the second request include an attach request or a tracking area update request. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 An example of a wireless communication system supporting network-supported radio access technology (RAT) switching in accordance with aspects of the present disclosure is illustrated.

[0021] Figure 2 An example of a wireless communication system supporting network-supported RAT switching in accordance with aspects of the present disclosure is illustrated.

[0022] Figure 3 and 4 An example of a process flow to support network-supported RAT switching in accordance with aspects of the present disclosure is illustrated.

[0023] Figure 5 and 6 A block diagram of a device supporting RAT switching based on network support according to aspects of the present disclosure is shown.

[0024] Figure 7 A block diagram of a communication manager supporting network-supported RAT switching is shown in accordance with aspects of the present disclosure.

[0025] Figure 8 A diagram of a system including a device supporting network-supported based RAT switching is shown in accordance with aspects of the present disclosure.

[0026] Fig. 9 and 10 A flow chart illustrating a method of supporting network-supported based RAT switching according to aspects of the present disclosure is shown.

[0027] Detailed Description

[0028] Some wireless communication systems may support multiple radio access technologies (RATs) for communication of UEs. Each RAT may be associated with a level of service provided to the UE and may include the fifth generation (5G), fourth generation (4G), third generation (3G), and second generation (2G) listed in descending order of the level of service provided to the UE. Thus, 5G may support additional services and may be the desired RAT for communication between the UE and a base station, while 2G may support limited services and may be used as a fallback when other RATs are unavailable or unsupported. In some wireless communication systems, 2G and 3G may be fallback options used by the UE when a 4G request from the UE is rejected.

[0029] In some cases, a network or a portion of a network may support 4G and may not support 5G, but the UE in the network may support both 4G and 5G. For example, with the introduction of 5G services, users may upgrade to UEs that support 5G faster than operators can update the network to support 5G services. In such cases, the UE may transmit a 4G request including 5G parameters to try to indicate the ability to use 5G (e.g., 5G in non-standalone (NSA) mode). However, because the network may not support 5G, the network may not be able to process the 5G parameters, and the request may be rejected by the network due to abnormal or unexpected reasons. Since the handling of these unexpected reasons may not be defined at the UE, the UE may misinterpret the rejection as being unable to use the 4G connection and fall back to 2G or 3G services in the network. That is, since the 4G request is rejected, and 2G and 3G are fallback options used by the UE when the 4G request is rejected, the UE may fall back to 2G or 3G when the 4G request is rejected. Therefore, even though the network may support 4G, the 4G request may be rejected if the 4G request includes 5G parameters. In this way, the UE may be downgraded to 2G or 3G, and the additional services provided by 4G may not be available to the UE.

[0030] As described herein, a wireless communication system may support efficient techniques for RAT selection while maximizing the services available to the UE. Specifically, when a UE is denied by a network node to communicate with a base station using a RAT due to unexpected reasons, the UE may be configured to continue using the RAT using the techniques described herein, or to fall back to an appropriate RAT. For example, after receiving a response indicating that a 4G request with 5G parameters is rejected, the UE may fall back to 4G without a 5G support option, rather than falling back to 2G or 3G. Unexpected reasons may be preconfigured and may be determined based on several factors, including the UE's subscription, a public land mobile network (PLMN) associated with the network node, etc. Further, unexpected reasons may include reasons for which the handling at the UE is not defined.

[0031] The various aspects of the present disclosure introduced above are described below in the context of a wireless communication system. Examples of processes and signaling exchanges that support network-supported RAT switching are subsequently described. Various aspects of the present disclosure are further illustrated and described by and with reference to apparatus diagrams, system diagrams, and flow charts related to network-supported RAT switching.

[0032] Figure 1 An example of a wireless communication system 100 that supports network-supported RAT switching according to various aspects of the present disclosure is illustrated. The wireless communication system 100 may include one or more base stations 105, one or more UEs 115, and a core network 130. In some examples, the wireless communication system 100 may be a long term evolution (LTE) network, an advanced LTE (LTE-A) network, an LTE-A Pro network, or a new radio (NR) network. In some examples, the wireless communication system 100 may support enhanced broadband communications, ultra-reliable (e.g., mission-critical) communications, low latency communications, communications with low-cost and low-complexity devices, or any combination thereof.

[0033] The base stations 105 may be dispersed throughout a geographic area to form the wireless communication system 100, and may be different forms of devices or devices with different capabilities. The base stations 105 and the UEs 115 may communicate wirelessly via one or more communication links 125. Each base station 105 may provide a coverage area 110 over which the UEs 115 and the base stations 105 may establish one or more communication links 125. The coverage area 110 may be an example of a geographic area over which the base stations 105 and the UEs 115 may support communication of signals according to one or more radio access technologies.

[0034] The UEs 115 may be dispersed throughout the coverage area 110 of the wireless communication system 100, and each UE 115 may be stationary or mobile, or stationary and mobile at different times. The UEs 115 may be different forms of devices or devices with different capabilities. Figure 1 Some example UEs 115 are illustrated in FIG. 1. The UEs 115 described herein may be capable of communicating with various types of devices, such as other UEs 115, base stations 105, or network equipment (e.g., core network nodes, relay devices, integrated access and backhaul (IAB) nodes, or other network equipment), such as Figure 1 as shown in .

[0035] Each base station 105 may communicate with the core network 130, or communicate with each other, or both. For example, the base station 105 may interface with the core network 130 via one or more backhaul links 120 (e.g., via S1, N2, N3 or other interfaces). The base stations 105 may communicate with each other directly (e.g., directly between the base stations 105), or indirectly (e.g., via the core network 130), or directly and indirectly on the backhaul link 120 (e.g., via X2, Xn or other interfaces). In some examples, the backhaul link 120 may be or include one or more wireless links.

[0036] One or more of the base stations 105 described herein may include or may be referred to by a person of ordinary skill in the art as a base transceiver station, a radio base station, an access point, a radio transceiver, a B node, an evolved B node (eNB), a next generation B node or a gigabit B node (any of which may be referred to as a gNB), a home B node, a home evolved B node, or other suitable terminology.

[0037] UE 115 may include or may be referred to as a mobile device, a wireless device, a remote device, a handheld device, or a subscriber device, or some other suitable terminology, where a "device" may also be referred to as a unit, a station, a terminal, a client, or the like. UE 115 may also include or be referred to as a personal electronic device, such as: a cellular phone, a personal digital assistant (PDA), a multimedia / entertainment device (e.g., a radio, an MP3 player, or a video device, etc.), a camera, a gaming device, a navigation / positioning device (e.g., a GNSS (Global Navigation Satellite System) device based on, for example, GPS (Global Positioning System), Beidou, GLONASS, or Galileo, or a ground-based device), a tablet computer, a laptop computer, a personal computer, a netbook, a smartbook, a personal computer, a smart device, a wearable device (e.g., a smart watch, smart clothing, smart glasses, virtual reality goggles, a smart wristband, smart jewelry (e.g., a smart ring, a smart bracelet)), a drone, a robot / robotic device, a vehicle, an in-vehicle device, a meter (e.g., a parking meter, an electricity meter, a gas meter, a water meter), a monitor, a gas pump, an appliance (e.g., a kitchen appliance, a washing machine, a dryer), a location tag, a medical / health care device, an implant, a sensor / actuator, a display, or any other suitable device configured to communicate via a wireless or wired medium. In some examples, UE 115 may include or be referred to as a wireless local loop (WLL) station, an Internet of Things (IoT) device, an Internet of Everything (IoE) device, or a machine type communication (MTC) device, etc., which may be implemented in various objects such as electrical appliances or vehicles, meters, etc.

[0038] The UE 115 described herein may be capable of communicating with various types of devices, such as other UEs 115, which may sometimes act as relays, as well as base stations 105 and network equipment including macro eNBs or gNBs, small cell eNBs or gNBs, relay base stations, etc. Figure 1 as shown in .

[0039] The UE 115 and the base station 105 may communicate wirelessly with each other via one or more communication links 125 on one or more carriers. The term "carrier" may refer to a set of radio frequency spectrum resources having a defined physical layer structure for supporting the communication link 125. For example, a carrier for the communication link 125 may include a portion of a radio frequency spectrum band (e.g., a bandwidth portion (BWP)) that operates according to one or more physical layer channels for a given radio access technology (e.g., LTE, LTE-A, LTE-A Pro, NR). Each physical layer channel may carry acquisition signaling (e.g., synchronization signals, system information), control signaling for coordinating carrier operations, user data, or other signaling. The wireless communication system 100 may support communication with the UE 115 using carrier aggregation or multi-carrier operation. The UE 115 may be configured to have multiple downlink component carriers and one or more uplink component carriers according to a carrier aggregation configuration. Carrier aggregation may be used in conjunction with both frequency division duplex (FDD) and time division duplex (TDD) component carriers.

[0040] The signal waveform transmitted on the carrier may include multiple subcarriers (e.g., using multi-carrier modulation (MCM) techniques, such as orthogonal frequency division multiplexing (OFDM) or discrete Fourier transform spread OFDM (DFT-S-OFDM)). In a system using MCM technology, a resource element may include a code element period (e.g., the duration of a modulation code element) and a subcarrier, where the code element period and the subcarrier spacing are inversely related. The number of bits carried by each resource element may depend on the modulation scheme (e.g., the order of the modulation scheme, the code rate of the modulation scheme, or both). Thus, the more resource elements received by UE 115 and the higher the order of the modulation scheme, the higher the data rate of UE 115 can be. Wireless communication resources may refer to a combination of radio frequency spectrum resources, time resources, and spatial resources (e.g., spatial layers or beams), and the use of multiple spatial layers can further improve the data rate or data integrity of communication with UE 115.

[0041] The time interval of the base station 105 or the UE 115 can be expressed as a multiple of a basic time unit, and the basic time unit can be, for example, a sampling period T s =1 / (Δf max ·Nf) seconds, where Δf maxNf may represent the maximum supported subcarrier spacing, and Nf may represent the maximum supported discrete Fourier transform (DFT) size. Time intervals of communication resources may be organized according to radio frames, each having a specified duration (e.g., 10 milliseconds (ms)). Each radio frame may be identified by a system frame number (SFN) (e.g., ranging from 0 to 1023).

[0042] Each frame may include a plurality of consecutively numbered subframes or time slots, and each subframe or time slot may have the same duration. In some examples, a frame may be divided into subframes (e.g., in the time domain), and each subframe may be further divided into a number of time slots. Alternatively, each frame may include a variable number of time slots, and the number of time slots may depend on the subcarrier spacing. Each time slot may include a number of code element periods (e.g., depending on the length of the cyclic prefix added before each code element period). In some wireless communication systems 100, the time slot may be further divided into a plurality of mini-time slots containing one or more code elements. Excluding the cyclic prefix, each code element period may include one or more (e.g., Nf) sampling periods. The duration of the code element period may depend on the subcarrier spacing or the operating frequency band.

[0043] A subframe, slot, mini-slot, or symbol may be the smallest scheduling unit (e.g., in the time domain) of the wireless communication system 100 and may be referred to as a transmission time interval (TTI). In some examples, the TTI duration (e.g., the number of symbol periods in a TTI) may be variable. Additionally or alternatively, the smallest scheduling unit of the wireless communication system 100 may be dynamically selected (e.g., in bursts of shortened TTIs (sTTIs)).

[0044] Physical channels may be multiplexed on a carrier according to various techniques. Physical control channels and physical data channels may be multiplexed on a downlink carrier, for example, using one or more of a time division multiplexing (TDM) technique, a frequency division multiplexing (FDM) technique, or a hybrid TDM-FDM technique. A control region (e.g., a control resource set (CORESET)) for a physical control channel may be defined by a number of symbol periods and may extend across a system bandwidth or a subset of a system bandwidth of a carrier. One or more control regions (e.g., CORESETs) may be configured for a set of UEs 115. For example, one or more of the UEs 115 may monitor or search a control region for control information according to one or more search space sets, and each search space set may include one or more control channel candidates in one or more aggregation levels arranged in a cascaded manner. An aggregation level for a control channel candidate may refer to the number of control channel resources (e.g., control channel elements (CCEs)) associated with coded information for a control information format having a given payload size. The search space sets may include a common search space set configured for transmitting control information to multiple UEs 115 and a UE-specific search space set for transmitting control information to a specific UE 115 .

[0045] Each base station 105 may provide communication coverage via one or more cells (e.g., macro cells, small cells, hot spots, or other types of cells, or any combination thereof). The term "cell" may refer to a logical communication entity used to communicate with a base station 105 (e.g., on a carrier), and may be associated with an identifier (e.g., a physical cell identifier (PCID), a virtual cell identifier (VCID), or other) used to distinguish adjacent cells. In some examples, a cell may also refer to a geographic coverage area 110 or a portion of a geographic coverage area 110 (e.g., a sector) on which a logical communication entity operates. The range of such a cell may range from a smaller area (e.g., a structure, a subset of a structure) to a larger area depending on various factors (such as the capabilities of the base station 105). For example, a cell may be or include a building, a subset of a building, or an external space between or overlapping a geographic coverage area 110, as well as other examples.

[0046] A macro cell generally covers a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access to UEs 115 that have service subscriptions with a network provider that supports the macro cell. A small cell may be associated with a lower power base station 105 (compared to a macro cell), and the small cell may operate in the same or different (e.g., licensed, unlicensed) frequency band as the macro cell. A small cell may provide unrestricted access to UEs 115 that have service subscriptions with a network provider, or may provide restricted access to UEs 115 associated with the small cell (e.g., UEs 115 in a closed subscriber group (CSG), UEs 115 associated with users in a home or office). A base station 105 may support one or more cells and may also support communications on one or more cells using one or more component carriers.

[0047] In some examples, the base stations 105 may be mobile and thus provide communication coverage for mobile geographic coverage areas 110. In some examples, different geographic coverage areas 110 associated with different technologies may overlap, but the different geographic coverage areas 110 may be supported by the same base station 105. In other examples, overlapping geographic coverage areas 110 associated with different technologies may be supported by different base stations 105. The wireless communication system 100 may include, for example, a heterogeneous network in which different types of base stations 105 provide coverage for various geographic coverage areas 110 using the same or different RATs.

[0048] The wireless communication system 100 may be configured to support ultra-reliable communication or low latency communication or various combinations thereof. For example, the wireless communication system 100 may be configured to support ultra-reliable low latency communication (URLLC) or mission-critical communication. UE 115 may be designed to support ultra-reliable, low latency or critical functions (e.g., mission-critical functions). Ultra-reliable communication may include private communication or group communication, and may be supported by one or more mission-critical services (such as mission-critical push-to-talk (MCPTT), mission-critical video (MCVideo), or mission-critical data (MCData). Support for mission-critical functions may include prioritization of services, and mission-critical services may be used for public safety or general commercial applications. The terms ultra-reliable, low latency, critical mission, and ultra-reliable low latency may be used interchangeably herein.

[0049] In some examples, UE 115 may also be able to communicate directly with other UE 115 over a device-to-device (D2D) communication link 135 (e.g., using a peer-to-peer (P2P) or D2D protocol). One or more UEs 115 utilizing D2D communication may be within a geographic coverage area 110 of a base station 105. Other UEs 115 in such a group may be outside the geographic coverage area 110 of the base station 105, or may not be able to receive transmissions from the base station 105 for other reasons. In some examples, each group of UEs 115 communicating via D2D communication may utilize a one-to-many (1:M) system, in which each UE 115 transmits to each other UE 115 in the group. In some examples, the base station 105 facilitates the scheduling of resources for D2D communication. In other cases, D2D communication is performed between each UE 115 without involving the base station 105.

[0050] The core network 130 may provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. The core network 130 may be an evolved packet core (EPC) or a 5G core (5GC), which may include one or more network nodes or entities 135. For example, the core network 130 may include at least one control plane entity (e.g., a mobility management entity (MME), an access and mobility management function (AMF)) that manages access and mobility, and at least one user plane entity (e.g., a serving gateway (S-GW), a packet data network (PDN) gateway (P-GW), or a user plane function (UPF)) that routes packets or interconnects to an external network. The control plane entity may manage non-access stratum (NAS) functions such as mobility, authentication, and bearer management of UE 115 served by a base station 105 associated with the core network 130. User IP packets may be delivered through a user plane entity, which may provide IP address allocation and other functions. The user plane entity may be connected to a network operator IP service 150. Operator IP services 150 may include access to the Internet, an intranet, an IP Multimedia Subsystem (IMS), or packet-switched streaming services.

[0051] Some network devices (such as base stations 105) may include subcomponents, such as access network entities 140, which may be examples of access node controllers (ANCs). Each access network entity 140 may communicate with each UE 115 through one or more other access network transport entities 145, which may be referred to as radio heads, smart radio heads, or transmission / reception points (TRPs). Each access network transport entity 145 may include one or more antenna panels. In some configurations, the various functions of each access network entity 140 or base station 105 may be distributed across various network devices (e.g., radio heads and ANCs) or merged into a single network device (e.g., base station 105).

[0052] The wireless communication system 100 may operate using one or more frequency bands, typically in the range of 300 megahertz (MHz) to 300 gigahertz (GHz). In general, the 300 MHz to 3 GHz region is referred to as the ultra-high frequency (UHF) region or decimeter band because the wavelengths range from about 1 decimeter to 1 meter long. UHF waves may be blocked or redirected by buildings and environmental features, but these waves may penetrate various structures sufficiently for macro cells to provide service to UEs 115 located indoors. Transmissions using UHF waves may be associated with smaller antennas and shorter ranges (e.g., less than 100 kilometers) than transmissions using smaller frequencies and longer waves in the high frequency (HF) or very high frequency (VHF) portions of the spectrum below 300 MHz.

[0053] The wireless communication system 100 may utilize both licensed and unlicensed radio frequency spectrum bands. For example, the wireless communication system 100 may employ licensed assisted access (LAA), LTE unlicensed (LTE-U) radio access technology, or NR technology in an unlicensed band (such as the 5 GHz industrial, scientific, and medical (ISM) band). When operating in an unlicensed radio frequency spectrum band, devices (such as base stations 105 and UEs 115) may employ carrier sensing for conflict detection and avoidance. In some examples, operations in an unlicensed band may be based on a carrier aggregation configuration (e.g., LAA) in coordination with component carriers operating in a licensed band. Operations in an unlicensed spectrum may include downlink transmissions, uplink transmissions, P2P transmissions, or D2D transmissions, among others.

[0054] The base station 105 or UE 115 may be equipped with multiple antennas, which can be used to employ technologies such as transmit diversity, receive diversity, multiple-input multiple-output (MIMO) communications, or beamforming. The antennas of the base station 105 or UE 115 may be located in one or more antenna arrays or antenna panels that can support MIMO operations or transmit or receive beamforming. For example, one or more base station antennas or antenna arrays may be co-located at an antenna assembly (such as an antenna tower). In some examples, the antennas or antenna arrays associated with the base station 105 may be located at different geographical locations. The base station 105 may have an antenna array having antenna ports of several rows and columns that the base station 105 can use to support beamforming for communications with the UE 115. Similarly, the UE 115 may have one or more antenna arrays that can support various MIMO or beamforming operations. Additionally or alternatively, the antenna panel may support radio frequency beamforming for signals transmitted via the antenna ports.

[0055] Beamforming (which may also be referred to as spatial filtering, directional transmission, or directional reception) is a signal processing technique that may be used at a transmitting device or a receiving device (e.g., a base station 105, a UE 115) to shape or steer an antenna beam (e.g., a transmit beam, a receive beam) along a spatial path between the transmitting device and the receiving device. Beamforming may be achieved by combining signals communicated via antenna elements of an antenna array so that some signals propagating at a particular orientation relative to the antenna array experience constructive interference, while other signals experience destructive interference. Adjustments to signals communicated via antenna elements may include the transmitting device or the receiving device applying an amplitude offset, a phase offset, or both to signals carried via antenna elements associated with the device. Adjustments associated with each antenna element may be defined by a set of beamforming weights associated with a particular orientation (e.g., relative to the antenna array of the transmitting device or the receiving device, or relative to some other orientation).

[0056] The wireless communication system 100 may support multiple RATs (e.g., 5G, 4G, 3G, and 2G) for communication of the UE 115 (e.g., via the base station 105). In some cases, the network in the wireless communication system 100 may support 4G and may not support 5G, but the UE 115 in the network may support both 4G and 5G. For example, with the introduction of 5G services, users may upgrade to 5G-enabled UEs 115 faster than operators may be able to update the network to support 5G services. In such cases, the UE 115 may transmit a 4G request with 5G parameters to indicate the ability to use 5G (e.g., in NSA mode). However, because the network may not support 5G, the network may not be able to process the 5G parameters, and the request may be rejected by the network due to abnormal or unexpected reasons. That is, the network (e.g., network node 135) may respond suddenly or unexpectedly because the network may not be able to manage or process 5G parameters or information elements (IEs) (e.g., parameters associated with dual connectivity NR (DCNR) or UE extended security capabilities introduced with 5G).

[0057] The above-mentioned abnormal or unexpected cause may correspond to a reason why the treatment for it at UE 115 is undefined. The treatment may be undefined due to the assumption that the network will support 5G if the UE 115 in the network supports 5G, or the treatment may be undefined in the case where the UE 115 attempts to establish communication. In one example, in response to a request from UE 115, the network may indicate that the UE 115 identity cannot be derived by the network (e.g., cause #9). This EPS mobility management (EMM) cause may be sent to UE 115 when the network cannot derive the identity of UE 115 from the globally unique temporary UE identity (GUTI), the serving temporary mobile subscriber identity (TMSI) (S-TMSI), the packet TMSI (P-TMSI), and the routing area identity (RAI). For example, there may be no matching identity context in the network, or the network may be unable to verify the identity of UE 115 due to a failed integrity check of the received message. However, for an attach procedure, this cause may be unexpected, since the attach request may be the first registration message transmitted to the network node 135, and it is expected that the MME would not save the UE identity before this first registration.

[0058] In another example, a network node 135 in the network may indicate that EPS services are not allowed in a PLMN linked to the network node 135 (e.g., cause #14). This EMM cause may be sent to the UE 115 transmitting a request (e.g., requesting services), or to the UE 115 when the network initiates a disconnect request in a PLMN that does not provide roaming for EPS services to the UE 115. However, in a home PLMN, this cause may be unexpected because the home PLMN should support EPS services. In yet another example, the network node 135 may indicate a protocol error (e.g., cause #111). However, it may also be unexpected to receive this rejection cause more than once (e.g., for an attach request or a tracking area update (TAU) request) or within the home PLMN.

[0059] Since the handling of these unexpected reasons may be undefined, the UE 115 may simply determine that the 4G request including the 5G parameters transmitted to the network is rejected. After a threshold number (e.g., five) of 4G requests from the UE 115 are rejected (e.g., for registration with the network), the UE 115 may disable 4G (e.g., LTE). The UE 115 may then move to a circuit switching (CS) RAT, such as 2G (e.g., Global System for Mobile Communications (GSM)) or 3G (e.g., Wideband Code Division Multiple Access (WCDMA)). Therefore, although the network may support 4G, the request from the UE may be rejected if the 4G request includes 5G parameters. In this way, the UE 115 may be downgraded to 2G or 3G, and the additional services provided by 4G may be lost (e.g., causing data interruption). Further, in some cases, if the operator is unable to support 2G or 3G (e.g., as a fallback), the UE 115 may not be able to obtain any service (e.g., when 4G requests from the UE 115 are continuously rejected by the network, resulting in no data transmission). When the UE 115 is roaming (e.g., transferred to a roaming PLMN), the chance that the UE 115 transmits a request that cannot be handled by the network may also increase.

[0060] As an example, UE 115 may transmit an initial attach request to the PLMN, and the PLMN may transmit a response to UE 115 indicating that the request was rejected because the UE 115 identity could not be derived by the PLMN (e.g., cause #9). Similarly, a TAU request may be rejected by the network for the same reason (e.g., upon a change in tracking area, or after an intra-RAT or inter-RAT handover from a CS domain to a PS domain in the same PLMN). The rejected TAU request may trigger an attach procedure for UE 115, and UE 115 may receive a response to the attach request indicating that the request was rejected because EPS services are not allowed in the PLMN (e.g., cause #14). Therefore, UE 115 may only receive CS services from the network (e.g., 2G or 3G). Further, the rejection received from the network may be non-integrity protected and may disable a denial of service (DoS) feature. As described herein, the wireless communication system 100 may support efficient techniques for selecting a RAT (eg, falling back from one RAT to an appropriate RAT) while maximizing services available to a UE 115 - a.

[0061] Figure 2 An example of a wireless communication system 200 that supports network-supported RAT switching according to various aspects of the present disclosure is illustrated. The wireless communication system 200 includes a UE 115-a, which may be a reference Figure 1 The wireless communication system 200 also includes a base station 105-a, which may be a base station 105-a. Figure 1 The wireless communication system 200 also includes a network node 135-a, which may be a reference Figure 1 An example of a network node 135 is depicted. Base station 105-a may provide communication coverage for coverage area 110-a. Wireless communication system 200 may implement aspects of wireless communication system 100. For example, wireless communication system 300 may support efficient techniques for falling back from one RAT to an appropriate RAT while maximizing services available to UE 115-a.

[0062] exist Figure 2In an example of , UE 115-a may identify a set of preconfigured causes with which network node 135-a may reject a request. UE 115-a may identify a set of preconfigured causes based on UE 115-a's subscription to an operator having a relationship with a PLMN associated with network node 135-a. A preconfigured cause may correspond to an unexpected cause for which handling at UE 115-a is not defined (e.g., an abnormal cause that is typically not visible or expected as part of a list of attach rejection causes or TAU rejection causes). In some cases, base station 105-a may signal UE 115-a of a set of preconfigured causes. In other cases, base station 105-a may signal UE 115-a of instructions for handling a set of causes, and UE 115-a may determine that all other causes are in the set of preconfigured causes. Thus, UE 115-a may identify a preconfigured cause based on signaling from base station 105-a, independently of signaling from base station 105-a, or some combination thereof.

[0063] Once the UE 115-a determines that a threshold number of requests are rejected by the network 135-a, and each rejection indicates one of the preconfigured reasons, the UE 115-a may fall back to the appropriate RAT using the techniques described herein. For example, the UE 115-a may support communications with a first RAT (e.g., 4G) and a second RAT (e.g., 5G), and the UE 115-a may transmit a request 205 (e.g., an attach request, a TAU request, or other request) with parameters associated with the second RAT to the network node 135-a (e.g., via the base station 105-a). The UE 115-a may then receive a response 210 indicating that the request was rejected with a specified rejection reason. In this example, the UE 115-a may determine that the rejection reason is in a preconfigured set of rejection reasons. Accordingly, UE 115-a may determine that the second RAT is not supported by network node 135-a (e.g., where a threshold number of requests are rejected for preconfigured reasons), and UE 115-a may transmit an updated request 215 without parameters associated with the second RAT to network node 135-b or to a different network node 135 (not shown).

[0064] Using these techniques, UE 115-a can maximize the services available to UE 115-a because UE 115-a can avoid downgrading to a third RAT (e.g., 3G) or a fourth RAT (e.g., 2G) that provides less service than the first RAT. The above-mentioned threshold number of requests (e.g., consecutive requests for the same PLMN) can be configured to be less than the threshold number of requests after which UE 115-a falls back to other RATs (e.g., third or fourth RATs). For example, in the case where UE 115-a is configured to fall back to other RATs after five requests are rejected, UE 115-a can be configured to discard parameters associated with the second RAT after three requests. In this way, UE 115-a may attempt at least some requests (e.g., two requests) that have parameters associated with the first RAT but not parameters related to the second RAT. In some cases, the UE may receive an indication of the threshold number of requests from base station 105-a. In other cases, the UE 115 - a may be configured to identify the threshold number of requests independently of signaling from the base station 105 - a .

[0065] In some cases, once a threshold number of requests from UE 115-a are rejected by network node 135-a for preconfigured reasons, and UE 115-a decides to transmit subsequent requests without parameters associated with the second RAT, UE 115-a may also add the PLMN associated with network node 135-b to the list of prohibited PLMNs. In such cases, UE 115-a may avoid transmitting requests with parameters associated with the second RAT to any network node associated with a PLMN in the list of prohibited PLMNs. A list of prohibited PLMNs (e.g., a list of prohibited PLMNs for 5G NSA capabilities) may be maintained for NSA cells, and the maximum number of entries for the list may be configurable (e.g., set to a certain value X). Further, communications with other equivalent PLMNs (ePLMNs) and equivalent home PLMNs (EHPLMNs) may not be affected (e.g., these PLMNs may not be added to the list of prohibited PLMNs). Upon restart (e.g., during power cycling) or upon Universal Subscriber Identity Module (USIM) removal, the list of prohibited PLMNs (e.g., for 5G NSA capabilities) may be removed. In some examples, low power mode (LPM) may not be considered another reset condition (e.g., the list may not be removed upon entering LPM).

[0066] Figure 3 An example of a process flow 300 for supporting RAT switching based on network support according to aspects of the present disclosure is illustrated. The process flow 300 illustrates aspects of a technique performed by a UE 115-b, which may be a reference Figure 1 and2 The process flow 300 also illustrates aspects of the technique performed by a base station 105-b, which may be a reference to Figure 1 and 2 The process flow 300 may support efficient techniques for falling back from one RAT to an appropriate RAT while maximizing the services available to the UE 115-b. Figure 3 In the example, UE 115-b may support communications according to a first RAT (e.g., 4G) and a second RAT (e.g., 5G).

[0067] At 305, UE 115-b may establish a connection with base station 105-b according to a first RAT (e.g., may perform a random access procedure and establish an RRC connection via a cellular cell associated with the first RAT). At 310, UE 115-b may transmit a first request associated with a bearer for a communication service to network node 135-b via the connection established with base station 105-b. For example, the first request may be an attachment request sent in an RRC setup complete message. The first request may include parameters associated with the second RAT. At 315, UE 115-b may receive a response from the first network node 135-a indicating that the first request was rejected, wherein the response includes a rejection cause that is one of a preconfigured cause in a set of preconfigured causes. The preconfigured cause may include a rejection cause for which handling at UE 115-b is not defined. For example, the preconfigured causes may include a first cause indicating that the base station 105-b or network node 135-b is unable to derive the identity of the UE 115-b (e.g., cause #9), a second cause indicating that EPS services are not allowed in the PLMN associated with the network node 135-b (e.g., cause #14), or a third cause indicating a protocol error (e.g., cause #111).

[0068] At 320, the UE 115-b may determine, based on the rejection cause being one of the preconfigured causes in the set of preconfigured causes, that the second RAT is not supported by the network node 135-b for communication with the UE 115-b. Specifically, the UE 115-b may determine that a threshold number of requests have been rejected for one of the preconfigured causes in the set of preconfigured causes (e.g., in the case where the UE 115-b receives N consecutive attach or TAU rejects with causes #9, #14, or #111 for the same LTE PLMN). Accordingly, at 325, the UE 115-b may transmit, based on the determination, to the network node 135-b a second request associated with a bearer for the communication service, wherein the second request does not include parameters associated with the second RAT. The threshold number of requests may be configurable (e.g., via signaling from the base station 105-b to the UE 115-b), or may be preconfigured at the UE 115-b. Further, the threshold number of requests may have a default value (e.g., 3), which may also be configurable (e.g., via signaling from base station 105-b to UE 115-b) or may be pre-configured at UE 115-b.

[0069] UE 115-b may also add the PLMN associated with network node 135-b to a list of PLMNs that are not supported by the second RAT, and UE 115-b may suppress transmitting requests with parameters associated with the second RAT to the network node associated with the PLMN. In some cases, if UE 115-b roams into a PLMN (e.g., a visited PLMN (VPLMN)) and an attach or TAU request is rejected with cause #14, UE 115-b may disable a previously specified behavior of adding the PLMN to a list of prohibited PLMNs for GPRS services. Further, in some cases, UE 115-b may be configured with a list of PLMNs to which the techniques described herein (e.g., event detection algorithms) are to be applied. If the list of PLMNs includes the PLMN associated with network node 135-b, UE 115-b may discard the parameters associated with the second RAT after a threshold number of requests including such parameters are rejected due to one of a preconfigured cause set. If the list of PLMNs is empty or does not include a PLMN associated with the network node 135-b, or if the list of PLMNs is not configured, the behavior described herein may be disabled (e.g., after receiving a threshold number of rejections for preconfigured reasons, the UE 115-b may not discard parameters associated with the second RAT).

[0070] Once network node 135-b receives the second request, network node 135-b may successfully process the parameters included in the second request and may accept or approve the request. For example, if the first and second requests are attachment requests, UE 115-b may successfully perform an attachment procedure and network node 135-b may establish an appropriate bearer for providing communication services to UE 115-b via the network (e.g., via network node 135-b or other network nodes (such as a packet data network gateway)). Alternatively, if the first and second requests are TAU requests, UE 115-b may successfully receive a TAU from base station 105-b.

[0071] Figure 4 An example of a process flow 400 for supporting RAT switching based on network support according to aspects of the present disclosure is illustrated. The process flow 400 illustrates aspects of a technique performed by a UE 115-c, which may be a reference Figure 1 and 2 The process flow 400 also illustrates aspects of the technique performed by a base station 105-c, which may be a reference to Figure 1 and 2 As described herein, process flow 400 may support efficient techniques for falling back from one RAT to an appropriate RAT while maximizing the services available to UE 115-c. Figure 4 In the example, UE 115-c may support communications according to a first RAT (e.g., 4G) and a second RAT (e.g., 5G), and UE 115-c may connect to a standalone (SA) 5G cell at base station 105-c.

[0072] At 405, the UE 115-c may establish a first connection with the base station 105-c (e.g., an SA cellular cell at the base station 105-c) according to the second RAT. At 410, the UE 115-c may transmit a first request associated with a bearer for a communication service to the network node 135-c via the connection established with the base station 105-c. For example, the first request may be an attachment request sent in an RRC setup complete message. The first request may include parameters associated with the second RAT. At 415, the UE 115-c may receive a response from the network node 135-c indicating that the first request was rejected, wherein the response includes a rejection cause that is one of the preconfigured causes in a set of preconfigured causes. The preconfigured cause may include a rejection cause for which the handling at the UE 115-c is not defined. For example, the preconfigured causes may include a first cause indicating that the base station 105-c or network node 135-c is unable to derive the identity of the UE 115-c (e.g., cause #9), a second cause indicating that EPS services are not allowed in the PLMN associated with the network node 135-c (e.g., cause #14), or a third cause indicating a protocol error (e.g., cause #111).

[0073] At 420, the UE 115-c may determine that the second RAT is not supported by the network node 135-c for communication with the UE 115-c based on the rejection reason being one of the preconfigured reasons in the set of preconfigured reasons. Specifically, the UE 115-c may determine that a threshold number of requests have been rejected for one of the preconfigured reasons in the set of preconfigured reasons (e.g., in the case where the UE 115-c receives N consecutive attach or TAU rejects with reasons #9, #14, or #111 for the same LTE PLMN). Therefore, at 425, the UE 115-c may establish a second connection with the base station 105-c or another base station 105 (not shown) according to the first RAT. For example, the UE 115-c may perform a cell search for the second connection or may otherwise detect different cells. At 430, the UE 115-c may then transmit, via a second connection with the base station 105-c or another base station 105, to the network node 135-c or another network node 135, a second request associated with a bearer for the communication service, wherein the second request may not include parameters associated with the second RAT. The threshold number of requests may be configurable (e.g., via signaling from the base station 105-c to the UE 115-c), or may be preconfigured at the UE 115-c. Further, the threshold number of requests may have a default value (e.g., 3), which may also be configurable (e.g., via signaling from the base station 105-c to the UE 115-c), or may be preconfigured at the UE 115-c.

[0074] UE 115-c may also add the PLMN associated with network node 135-c to a list of PLMNs that are not supported by the second RAT, and UE 115-c may refrain from transmitting requests with parameters associated with the second RAT to the network node associated with the PLMN. Figure 4 In the example of , UE 115-c may disable SA communications associated with the second RAT (e.g., SA 5G), and UE 115-c may block the PLMN for 5G SA services. Subsequently, UE 115-c may attempt data services on the first RAT (e.g., 4G or LTE). If UE 115-c roams into a PLMN (e.g., a visited PLMN (VPLMN)) and the attach or TAU request is rejected with reason #14, UE 115-c may disable the previously specified behavior of adding the PLMN to the list of prohibited PLMNs for GPRS services.

[0075] Additionally, in some cases, the UE 115-c may be configured with a list of PLMNs to which the techniques described herein (e.g., event detection algorithms) are to be applied. If the list of PLMNs includes a PLMN associated with the network node 135-c, the UE 115-c may discard parameters associated with the second RAT after a threshold number of requests including such parameters are rejected due to one of a preconfigured set of reasons. If the list of PLMNs is empty or does not include a PLMN associated with the network node 135-c, or if the list of PLMNs is not configured, the behavior described herein may be disabled (e.g., the UE 115-c may not discard parameters associated with the second RAT after receiving a threshold number of rejections for preconfigured reasons).

[0076] Once the network node 135-c receives the second request, the network node 135-c may successfully process the parameters included in the second request and may accept or approve the request. For example, if the first and second requests are attachment requests, the network node 135-c may successfully establish a bearer for providing communication services to the UE 115-c within the network (e.g., via the network node 135-c or other network nodes (such as, a packet data network gateway)). Specifically, the first connection according to the second RAT may be connected to the SA cell at the base station 105-c, and the second connection according to the first RAT may be associated with a different cell at the base station 105-c (e.g., a cell supporting the first RAT) or a cell of another base station 105 (e.g., a cell supporting the first RAT, or a cell supporting the first RAT or the second RAT when the other base station 105 is associated with a different PLMN). Therefore, after the second request, the UE 115-c may attach to a different cell (e.g., a cell supporting the first RAT) at the base station 105-c or another base station 105. Alternatively, if the first and second requests are TAU requests, the UE 115 - c may successfully receive a tracking area update from the base station 105 - c .

[0077] Figure 5 A block diagram 500 of a device 505 supporting RAT switching based on network support according to aspects of the present disclosure is shown. The device 505 may be an example of aspects of the UE 115 as described herein. The device 505 may include a receiver 510, a communication manager 515, and a transmitter 520. The device 505 may also include a processor. Each of these components may be in communication with each other (e.g., via one or more buses).

[0078] The receiver 510 may receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to RAT switching based on network support, etc.). The information may be passed to other components of the device 505. The receiver 510 may be a reference Figure 8 Examples of aspects of the described transceiver 820. The receiver 510 may utilize a single antenna or a collection of antennas.

[0079] The communication manager 515 may establish a connection with a base station according to a first radio access technology; transmit a first request associated with a bearer for a communication service to a first network node via the connection established with the base station, the first request including parameters associated with a second radio access technology; based on the determination, transmit a second request associated with a bearer for a communication service to the first network node, the second request not including parameters associated with the second radio access technology; receive a response from the first network node indicating that the first request is rejected, the response including a rejection cause that is one of the preconfigured causes in a preconfigured cause set; and determine that the second radio access technology is not supported by the first network node for communication with the UE based on the rejection cause being one of the preconfigured causes in the preconfigured cause set.

[0080] The communication manager 515 may also establish a first connection with the first base station according to the second radio access technology; based on the determination, establish a second connection with the first base station or the second base station according to the first radio access technology; transmit a first request associated with a bearer for a communication service to the first network node via the first connection with the first base station, the first request including parameters associated with the second radio access technology; based on the determination, transmit a second request associated with a bearer for a communication service to the first network node or the second network node via the second connection with the first base station or the second base station, the second request not including parameters associated with the second radio access technology; receive a response from the first base station indicating that the first request is rejected, the response including a rejection cause as one of the preconfigured causes in the preconfigured cause set; and determine that the second radio access technology is not supported by the first network node for communication with the UE based on the rejection cause being one of the preconfigured causes in the preconfigured cause set. The communication manager 515 may be an example of aspects of the communication manager 810 described herein.

[0081] The communication manager 515 or its subcomponents may be implemented in hardware, in code (e.g., software or firmware) executed by a processor, or any combination thereof. If implemented in code executed by a processor, the functions of the communication manager 515 or its subcomponents may be performed by a general purpose processor, a DSP, an application specific integrated circuit (ASIC), an FPGA or other programmable logic device designed to perform the functions described in the present disclosure, discrete gate or transistor logic, discrete hardware components, or any combination thereof.

[0082] The communication manager 515 or its subcomponents may be physically located at various locations, including being distributed such that portions of functionality are implemented by one or more physical components at different physical locations. In some examples, according to various aspects of the present disclosure, the communication manager 515 or its subcomponents may be separate and distinct components. In some examples, according to various aspects of the present disclosure, the communication manager 515 or its subcomponents may be combined with one or more other hardware components, including but not limited to input / output (I / O) components, a transceiver, a network server, another computing device, one or more other components described in the present disclosure, or a combination thereof.

[0083] The transmitter 520 may transmit signals generated by other components of the device 505. In some examples, the transmitter 520 may be co-located with the receiver 510 in a transceiver module. For example, the transmitter 520 may be a reference Figure 8 Examples of aspects of the described transceiver 820. The transmitter 520 may utilize a single antenna or a collection of antennas.

[0084] Figure 6 A block diagram 600 of a device 605 supporting RAT switching based on network support according to aspects of the present disclosure is shown. The device 605 may be an example of aspects of the device 505 or UE 115 as described herein. The device 605 may include a receiver 610, a communication manager 615, and a transmitter 640. The device 605 may also include a processor. Each of these components may be in communication with each other (e.g., via one or more buses).

[0085] The receiver 610 may receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to RAT switching based on network support, etc.). The information may be passed to other components of the device 605. The receiver 610 may be a reference Figure 8 Examples of aspects of the described transceiver 820. The receiver 610 may utilize a single antenna or a collection of antennas.

[0086] The communication manager 615 may be an example of aspects of the communication manager 515 as described herein. The communication manager 615 may include a connection manager 620, a request manager 625, a response manager 630, and a RAT manager 635. The communication manager 615 may be an example of aspects of the communication manager 810 as described herein.

[0087] The connection manager 620 may establish a connection with the base station according to the first radio access technology. The request manager 625 may transmit a first request associated with a bearer for a communication service to the first network node via the connection established with the base station, the first request including parameters associated with the second radio access technology. The response manager 630 may receive a response from the first network node indicating that the first request is rejected, the response including a rejection cause that is one of the preconfigured causes in the preconfigured cause set. The RAT manager 635 may determine that the second radio access technology is not supported by the first network node for communication with the UE based on the rejection cause being one of the preconfigured causes in the preconfigured cause set. The request manager 625 may transmit a second request associated with a bearer for a communication service to the first network node based on the determination, the second request not including parameters associated with the second radio access technology.

[0088] The connection manager 620 may establish a first connection with the first base station according to the second radio access technology. The request manager 625 may transmit a first request associated with a bearer for a communication service to the first network node via the first connection established with the first base station, the first request including parameters associated with the second radio access technology. The response manager 630 may receive a response indicating that the first request is rejected from the first base station, the response including a rejection cause that is one of the preconfigured causes in the preconfigured cause set. The RAT manager 635 may determine that the second radio access technology is not supported by the first network node for communication with the UE based on the rejection cause being one of the preconfigured causes in the preconfigured cause set. The connection manager 620 may establish a second connection with the first base station or the second base station according to the first radio access technology based on the determination. The request manager 625 may transmit a second request associated with a bearer for a communication service to the first network node or the second network node via the second connection with the first base station or the second base station based on the determination, the second request not including parameters associated with the second radio access technology.

[0089] The transmitter 640 may transmit signals generated by other components of the device 605. In some examples, the transmitter 640 may be co-located with the receiver 610 in a transceiver module. For example, the transmitter 640 may be a reference Figure 8 Examples of aspects of the described transceiver 820. The transmitter 640 may utilize a single antenna or a collection of antennas.

[0090] Figure 7A block diagram 700 of a communication manager 705 supporting RAT switching based on network support is shown in accordance with aspects of the present disclosure. The communication manager 705 may be an example of aspects of the communication manager 515, the communication manager 615, or the communication manager 810 described herein. The communication manager 705 may include a connection manager 710, a request manager 715, a response manager 720, a RAT manager 725, a PLMN manager 730, and a rejection threshold manager 735. Each of these modules may communicate directly or indirectly with each other (e.g., via one or more buses).

[0091] The connection manager 710 may establish a connection with the base station according to the first radio access technology. In some examples, the connection manager 710 may establish a first connection with the first base station according to the second radio access technology. In some examples, the connection manager 710 may establish a second connection with the first base station or the second base station according to the first radio access technology based on the determination. The request manager 715 may transmit a first request associated with a bearer for a communication service to the first network node via the connection established with the base station, the first request including parameters associated with the second radio access technology. In some examples, the request manager 715 may transmit a second request associated with a bearer for a communication service to the first network node based on the determination, the second request not including parameters associated with the second radio access technology.

[0092] In some examples, the request manager 715 may transmit a first request associated with a bearer for a communication service to the first network node via a first connection established with the first base station, the first request including parameters associated with the second radio access technology. In some examples, the request manager 715 may transmit a second request associated with a bearer for a communication service to the first network node or the second network node via a second connection with the first base station or the second base station based on the determination, the second request not including parameters associated with the second radio access technology. In some examples, the request manager 715 may suppress transmitting a request including parameters associated with the second radio access technology to a network node associated with the PLMN based on adding the PLMN to the list. In some examples, the request manager 715 may transmit a second request to the first network node based on receiving a threshold number of responses, the second request not including parameters associated with the second radio access technology.

[0093] In some examples, the request manager 715 may suppress transmitting a request including parameters associated with the second radio access technology to a network node associated with the PLMN based on adding the PLMN to the list. In some examples, the request manager 715 may transmit a second request including parameters associated with the first radio access technology to the first network node or the second network node based on receiving a threshold number of responses. In some cases, the first request and the second request include an attach request or a tracking area update request. In some cases, the first request and the second request include an attach request or a tracking area update request.

[0094] The response manager 720 may receive a response from the first network node indicating that the first request is rejected, the response including a rejection cause as one of the preconfigured causes in the preconfigured cause set. In some examples, the response manager 720 may receive a response from the first base station indicating that the first request is rejected, the response including a rejection cause as one of the preconfigured causes in the preconfigured cause set. In some cases, the preconfigured cause includes a rejection cause for which the handling at the UE is not defined. In some cases, the preconfigured cause includes a first cause indicating that the base station cannot derive the identity of the UE, a second cause indicating that an evolved packet system (EPS) service is not allowed in a public land mobile network (PLMN) associated with the first network node, and one or more of a third cause indicating a protocol error. In some cases, the preconfigured cause includes a rejection cause for which the handling at the UE is not defined. In some cases, the preconfigured causes include one or more of a first cause indicating that the base station cannot derive the identity of the UE, a second cause indicating that Evolved Packet System (EPS) service is not allowed in a public land mobile network (PLMN) associated with the first network node, and a third cause indicating a protocol error.

[0095] The RAT manager 725 may determine that the second radio access technology is not supported by the first network node for communication with the UE based on the rejection reason being one of the preconfigured reasons in the preconfigured cause set. In some examples, the RAT manager 725 may determine that the second radio access technology is not supported by the first network node for communication with the UE based on the rejection reason being one of the preconfigured reasons in the preconfigured cause set. In some examples, the RAT manager 725 may determine that the second radio access technology is not supported by the first network node based on the UE's subscription to an operator having a relationship with a public land mobile network (PLMN) associated with the first network node. In some cases, determining that the second radio access technology is not supported by the first network node is based on the UE's subscription to an operator having a relationship with a public land mobile network (PLMN) associated with the first network node.

[0096] The PLMN manager 730 may add a public land mobile network (PLMN) associated with the first network node to a list of PLMNs that are not supported by the second radio access technology. In some examples, the PLMN manager 730 may add a public land mobile network (PLMN) associated with the first network node to a list of PLMNs that are not supported by the second radio access technology. The rejection threshold manager 735 may receive a threshold number of responses from the first network node, each response including a rejection cause as one of the preconfigured causes in the preconfigured cause set. In some examples, the rejection threshold manager 735 may receive an indication of a threshold number of responses to which the UE is to transmit a second request thereafter. In some examples, the rejection threshold manager 735 may receive a threshold number of responses from the first network node, each response including a rejection cause as one of the preconfigured causes in the preconfigured cause set. In some examples, the rejection threshold manager 735 may receive an indication of a threshold number of responses to which the UE is to transmit a second request thereafter.

[0097] Figure 8 A diagram of a system 800 including a device 805 supporting RAT switching based on network support according to various aspects of the present disclosure is shown. The device 805 may be an example of a device 505, a device 605, or a UE 115 as described herein or include components of these devices. The device 805 may include components for two-way voice and data communications, including components for transmitting and receiving communications, including a communication manager 810, an I / O controller 815, a transceiver 820, an antenna 825, a memory 830, and a processor 840. These components may be in electronic communication via one or more buses (e.g., a bus 845).

[0098] The communication manager 810 may establish a connection with a base station according to a first radio access technology; transmit a first request associated with a bearer for a communication service to a first network node via the connection established with the base station, the first request including parameters associated with a second radio access technology; based on the determination, transmit a second request associated with a bearer for a communication service to the first network node, the second request not including parameters associated with the second radio access technology; receive a response from the first network node indicating that the first request is rejected, the response including a rejection cause that is one of the preconfigured causes in a preconfigured cause set; and determine that the second radio access technology is not supported by the first network node for communication with the UE based on the rejection cause being one of the preconfigured causes in the preconfigured cause set.

[0099] The communication manager 810 may also establish a first connection with the first base station according to the second radio access technology; based on the determination, establish a second connection with the first base station or the second base station according to the first radio access technology; transmit a first request associated with a bearer for a communication service to the first network node via the first connection with the first base station, the first request including parameters associated with the second radio access technology; based on the determination, transmit a second request associated with a bearer for a communication service to the first network node or the second network node via the second connection with the first base station or the second base station, the second request not including parameters associated with the second radio access technology; receive a response from the first base station indicating that the first request is rejected, the response including a rejection cause that is one of the preconfigured causes in the preconfigured cause set; and determine that the second radio access technology is not supported by the first network node for communication with the UE based on the rejection cause being one of the preconfigured causes in the preconfigured cause set.

[0100] I / O controller 815 can manage input and output signals of device 805. I / O controller 815 can also manage peripheral devices that are not integrated into device 805. In some cases, I / O controller 815 can represent a physical connection or port to an external peripheral device. In some cases, I / O controller 815 can utilize an operating system, such as MS- MS- OS / Or another known operating system. In other cases, I / O controller 815 may represent or interact with a modem, keyboard, mouse, touch screen, or similar device. In some cases, I / O controller 815 may be implemented as part of a processor. In some cases, a user may interact with device 805 via I / O controller 815 or via hardware components controlled by I / O controller 815.

[0101] The transceiver 820 may communicate bidirectionally via one or more antennas, wired or wireless links, as described above. For example, the transceiver 820 may represent a wireless transceiver and may communicate bidirectionally with another wireless transceiver. The transceiver 820 may also include a modem to modulate packets and provide the modulated packets to an antenna for transmission, and demodulate packets received from an antenna.

[0102] In some cases, a wireless device may include a single antenna 825. However, in some cases, the device may have more than one antenna 825, which may be capable of transmitting or receiving multiple wireless transmissions concurrently.

[0103] The memory 830 may include RAM and ROM. The memory 830 may store computer-readable, computer-executable code 835 including instructions that, when executed, cause the processor to perform the various functions described herein. In some cases, the memory 830 may include, among other things, a BIOS that may control basic hardware or software operations, such as interaction with peripheral components or devices.

[0104] The processor 840 may include an intelligent hardware device (e.g., a general-purpose processor, a DSP, a CPU, a microcontroller, an ASIC, an FPGA, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof). In some cases, the processor 840 may be configured to operate a memory array using a memory controller. In other cases, the memory controller may be integrated into the processor 840. The processor 840 may be configured to execute computer-readable instructions stored in a memory (e.g., memory 830) so that the device 805 performs various functions (e.g., functions or tasks of supporting RAT switching based on network support in NR).

[0105] The code 835 may include instructions for implementing various aspects of the present disclosure, including instructions for supporting wireless communications. The code 835 may be stored in a non-transitory computer-readable medium, such as a system memory or other type of memory. In some cases, the code 835 may not be directly executed by the processor 840, but may cause a computer (e.g., when compiled and executed) to perform the functions described herein.

[0106] Fig. 9 A flow chart illustrating a method 900 for supporting RAT switching based on network support according to aspects of the present disclosure is shown. The operations of the method 900 may be implemented by a UE 115 or a component thereof as described herein. For example, the operations of the method 900 may be implemented by a UE 115 or a component thereof as described herein. Figures 5 to 8 In some examples, the UE may execute an instruction set to control the functional elements of the UE to perform the functions described below. Additionally or alternatively, the UE may use dedicated hardware to perform various aspects of the functions described below.

[0107] At 905, the UE may establish a connection with a base station according to a first radio access technology. The operations of 905 may be performed according to the methods described herein. In some examples, aspects of the operations of 905 may be as described with reference to Figures 5 to 8 The connection manager described is implemented.

[0108] At 910, the UE may transmit, via a connection established with the base station, to a first network node a first request associated with a bearer for a communication service, the first request including parameters associated with a second radio access technology. The operations of 910 may be performed according to the methods described herein. In some examples, aspects of the operations of 910 may be performed as described in reference to Figures 5 to 8 The request manager described is executed.

[0109] At 915, the UE may receive a response from the first network node indicating that the first request is rejected, the response including a rejection reason as one of the preconfigured reasons in the preconfigured cause set. The operations of 915 may be performed according to the methods described herein. In some examples, aspects of the operations of 915 may be performed as described in reference to Figures 5 to 8 The response manager described is executed.

[0110] At 920, the UE may determine that the second radio access technology is not supported by the first network node for communication with the UE based on the rejection reason being one of the preconfigured reasons in the preconfigured cause set. The operations of 920 may be performed according to the methods described herein. In some examples, aspects of the operations of 920 may be performed as described with reference to Figures 5 to 8 The RAT manager described herein is used to perform the above operations.

[0111] At 925, the UE may transmit, based on the determination, to the first network node a second request associated with a bearer for the communication service, the second request not including parameters associated with the second radio access technology. The operations of 925 may be performed according to the methods described herein. In some examples, aspects of the operations of 925 may be performed as described in reference to Figures 5 to 8 The request manager described is executed.

[0112] Fig.10 A flow chart illustrating a method 1000 for supporting RAT switching based on network support according to aspects of the present disclosure is shown. The operations of the method 1000 may be implemented by a UE 115 or a component thereof as described herein. For example, the operations of the method 1000 may be implemented by a UE 115 or a component thereof as described herein. Figures 5 to 8 In some examples, the UE may execute an instruction set to control the functional elements of the UE to perform the functions described below. Additionally or alternatively, the UE may use dedicated hardware to perform various aspects of the functions described below.

[0113] At 1005, the UE may establish a first connection with the first base station according to the second radio access technology. The operations of 1005 may be performed according to the methods described herein. In some examples, aspects of the operations of 1005 may be as described with reference to Figures 5 to 8 The connection manager described is implemented.

[0114] At 1010, the UE may transmit a first request associated with a bearer for a communication service to a first network node via a first connection established with a first base station, the first request including parameters associated with a second radio access technology. The operations of 1010 may be performed according to the methods described herein. In some examples, aspects of the operations of 1010 may be performed as described in reference to Figures 5 to 8 The request manager described is executed.

[0115] At 1015, the UE may receive a response from the first base station indicating that the first request is rejected, the response including a rejection cause as one of the preconfigured causes in the preconfigured cause set. The operations of 1015 may be performed according to the methods described herein. In some examples, aspects of the operations of 1015 may be performed as described in reference to Figures 5 to 8 The response manager described is executed.

[0116] At 1020, the UE may determine that the second radio access technology is not supported by the first network node for communication with the UE based on the rejection reason being one of the preconfigured reasons in the preconfigured reason set. The operations of 1020 may be performed according to the methods described herein. In some examples, aspects of the operations of 1020 may be performed as described with reference to Figures 5 to 8 The RAT manager described herein is used to perform the above operations.

[0117] At 1025, the UE may establish a second connection with the first base station or the second base station based on the first radio access technology based on the determination. The operations of 1025 may be performed according to the methods described herein. In some examples, aspects of the operations of 1025 may be as described with reference to Figures 5 to 8 The connection manager described is implemented.

[0118] At 1030, the UE may transmit, based on the determination, to the first network node or the second network node via a second connection with the first base station or the second base station, a second request associated with a bearer for the communication service, the second request not including parameters associated with the second radio access technology. The operations of 1030 may be performed according to the methods described herein. In some examples, aspects of the operations of 1030 may be performed as described with reference to Figures 5 to 8 The request manager described is executed.

[0119] It should be noted that the methods described herein describe possible implementations, and that the various operations and steps may be rearranged or otherwise modified and other implementations are possible. Furthermore, aspects from two or more methods may be combined.

[0120] Although aspects of LTE, LTE-A, LTE-A Pro, or NR systems may be described for example purposes, and LTE, LTE-A, LTE-A Pro, or NR terminology may be used in much of the description, the techniques described herein may also be applicable to networks other than LTE, LTE-A, LTE-A Pro, or NR networks. For example, the described techniques may be applied to various other wireless communication systems, such as Ultra Mobile Broadband (UMB), Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM, and other systems and radio technologies not explicitly mentioned herein.

[0121] The information and signals described herein may be represented using any of a variety of different techniques and technologies. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referred to throughout this description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0122] The various illustrative blocks and components described in conjunction with the disclosure herein may be implemented or performed with a general purpose processor, a DSP, an ASIC, a CPU, 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 processor, controller, microcontroller, or state machine. The 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).

[0123] The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. Software should be broadly interpreted as meaning instructions, instruction sets, codes, code segments, program codes, programs, subroutines, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether they are described in software, firmware, middleware, microcode, hardware description language, or other terms. If implemented in software executed by a processor, each function may be stored on a computer-readable medium or transmitted therefrom as one or more instructions or codes. Other examples and implementations fall within the scope of the present disclosure and the appended claims. For example, due to the nature of software, the functions described herein may be implemented using software executed by a processor, hardware, firmware, hard wiring, or any combination thereof. The features that implement the functions may also be physically located in various locations, including being distributed so that the various parts of the functions are implemented at different physical locations.

[0124] Computer readable medium includes both non-transient computer storage medium and communication medium, and it includes any medium that facilitates computer program to transfer from one place to another place.Non-transient storage medium can be any available medium that can be accessed by general or special-purpose computer.As an example and not limitation, non-transient computer readable medium can include random access memory (RAM), read-only memory (ROM), electrically erasable programmable ROM (EEPROM), flash memory, compact disk (CD) ROM or other optical disk storage, disk storage or other magnetic storage device, or can be used to carry or store instruction or data structure form of desired program code means and can be accessed by general or special-purpose computer or general or special-purpose processor any other non-transient medium.Similarly, any connection is also properly referred to as computer readable medium.For example, if software is transmitted from website, server or other remote source using coaxial cable, optical fiber cable, twisted pair, digital subscriber line (DSL) or wireless technology such as infrared, radio and microwave, then the coaxial cable, optical fiber cable, twisted pair, DSL or wireless technology such as infrared, radio and microwave are just included in the definition of computer readable medium. Disk and disc as used herein include CDs, laser discs, optical discs, digital versatile discs (DVDs), floppy disks, and Blu-ray discs, where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above are also included within the scope of computer-readable media.

[0125] As used herein (including in the claims), "or" used in a listing of items (e.g., a listing of items with a phrase such as "at least one of" or "one or more of") indicates an inclusive listing, such that, for example, a listing of at least one of A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C). Likewise, as used herein, the phrase "based on" should not be interpreted as referring to a closed set of conditions. For example, an example step described as "based on condition A" may be based on both condition A and condition B without departing from the scope of the present disclosure. In other words, as used herein, the phrase "based on" should be interpreted in the same manner as the phrase "based at least in part on". As used herein, the term "and / or" used in a listing of two or more items means that any of the listed items may be employed alone, or any combination of two or more of the listed items may be employed. For example, if a composition is described as comprising components A, B, and / or C, the composition may comprise only A; only B; only C; a combination of A and B; a combination of A and C; a combination of B and C; or a combination of A, B, and C.

[0126] In the accompanying drawings, similar components or features may have the same reference number. In addition, various components of the same type may be distinguished by following the reference number with a dash and a second reference number that distinguishes between similar components. If only the first reference number is used in the specification, the description may apply to any of the similar components having the same first reference number regardless of the second reference number, or other subsequent reference numbers.

[0127] The descriptions set forth herein in conjunction with the accompanying drawings describe example configurations and do not represent all examples that can be implemented or fall within the scope of the claims. The term "example" as used herein means "used as an example, instance, or illustration" and does not mean "better than" or "better than other examples." This detailed description includes specific details to provide an understanding of the described techniques. However, these techniques may be practiced without these specific details. In some instances, known structures and devices are shown in block diagram form to avoid obscuring the concepts of the described examples.

[0128] The description herein is provided to enable one of ordinary skill in the art to make or use the present disclosure. Various modifications to the present disclosure will be apparent to one of ordinary skill in the art, and the universal principles defined herein may be applied to other variations without departing from the scope of the present disclosure. Thus, the present disclosure is not limited to the examples and designs described herein, but should be granted the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for supporting wireless communications of a first radio access technology and a second radio access technology at a user equipment (UE), the method comprising: establishing a connection with a base station according to the first radio access technology; transmitting, via the connection established with the base station, to a first network node, a first request associated with a bearer for a communication service, the first request comprising parameters associated with the second radio access technology; receiving a response from the first network node indicating that the first request is rejected, the response including a rejection reason that is one of a preconfigured set of reasons; determining, based at least in part on the rejection reason being one of the preconfigured set of reasons, that the second radio access technology is not supported by the first network node for communication with the UE; as well as Based at least in part on the determination, transmitting to the first network node a second request associated with a bearer for the communication service, the second request excluding parameters associated with the second radio access technology.

2. The method of claim 1, further comprising: adding a public land mobile network (PLMN) associated with the first network node to a list of PLMNs that are not supported by the second radio access technology; as well as Based at least in part on adding the PLMN to the list, transmitting a request including parameters associated with the second radio access technology to a network node associated with the PLMN is suppressed.

3. The method of claim 1, further comprising: receiving a threshold number of responses from the first network node, each response including a rejection cause as one of the preconfigured causes in the set of preconfigured causes; as well as Based at least in part on receiving the threshold number of responses, transmitting the second request to the first network node, the second request excluding parameters associated with the second radio access technology.

4. The method of claim 3, further comprising: An indication is received that the threshold number of responses after which the UE is to transmit the second request.

5. The method of claim 1, wherein: Determining that the second radio access technology is not supported by the first network node is based at least in part on a subscription of the UE to an operator having a relationship with a public land mobile network (PLMN) associated with the first network node.

6. The method of claim 1, wherein the preconfigured cause comprises a rejection cause for which handling at the UE is undefined.

7. The method of claim 1 , wherein the preconfigured causes include one or more of a first cause indicating that the base station cannot derive the identity of the UE, a second cause indicating that Evolved Packet System (EPS) service is not allowed in a public land mobile network (PLMN) associated with the first network node, and a third cause indicating a protocol error.

8. The method of claim 1, wherein the first request and the second request comprise an attach request or a tracking area update request.

9. A method for supporting wireless communications of a first radio access technology and a second radio access technology at a user equipment (UE), the method comprising: establishing a first connection with a first base station according to the second radio access technology; transmitting, via the first connection with the first base station, to a first network node a first request associated with a bearer for a communication service, the first request comprising parameters associated with the second radio access technology; receiving a response from the first base station indicating that the first request is rejected, the response including a rejection cause that is one of a preconfigured cause in a preconfigured set of causes; determining, based at least in part on the rejection reason being one of the preconfigured set of reasons, that the second radio access technology is not supported by the first network node for communication with the UE; establishing a second connection with the first base station or a second base station according to the first radio access technology based at least in part on the determining; as well as Based at least in part on the determination, transmitting to the first network node or the second network node via the second connection with the first base station or the second base station a second request associated with a bearer for the communication service, the second request not including parameters associated with the second radio access technology.

10. The method of claim 9, further comprising: adding a public land mobile network (PLMN) associated with the first network node to a list of PLMNs that are not supported by the second radio access technology; as well as Based at least in part on adding the PLMN to the list, transmitting a request including parameters associated with the second radio access technology to a network node associated with the PLMN is suppressed.

11. The method of claim 9, further comprising: receiving a threshold number of responses from the first network node, each response including a rejection cause as one of the preconfigured causes in the set of preconfigured causes; as well as Based at least in part on receiving the threshold number of responses, transmitting the second request to the first network node or the second network node, the second request including parameters associated with the first radio access technology.

12. The method of claim 11, further comprising: An indication is received that the threshold number of responses after which the UE is to transmit the second request.

13. The method of claim 9, wherein determining that the second radio access technology is not supported by the first network node is based at least in part on a subscription of the UE to an operator having a relationship with a public land mobile network (PLMN) associated with the first network node.

14. The method of claim 9, wherein the preconfigured cause comprises a rejection cause for which handling at the UE is undefined.

15. The method of claim 9, wherein the preconfigured causes include one or more of a first cause indicating that the base station cannot derive the identity of the UE, a second cause indicating that Evolved Packet System (EPS) service is not allowed in a public land mobile network (PLMN) associated with the first network node, and a third cause indicating a protocol error.

16. The method of claim 9, wherein the first request and the second request comprise an attach request or a tracking area update request.

17. An apparatus for supporting wireless communications of a first radio access technology and a second radio access technology at a user equipment (UE), the apparatus comprising: processor; a memory coupled to the processor; as well as Instructions stored in the memory and executable by the processor to cause the device to perform the following operations: establishing a connection with a base station according to the first radio access technology; transmitting, via the connection established with the base station, to a first network node, a first request associated with a bearer for a communication service, the first request comprising parameters associated with the second radio access technology; receiving a response from the first network node indicating that the first request is rejected, the response including a rejection reason that is one of a preconfigured set of reasons; determining, based at least in part on the rejection reason being one of the preconfigured set of reasons, that the second radio access technology is not supported by the first network node for communication with the UE; as well as Based at least in part on the determination, transmitting to the first network node a second request associated with a bearer for the communication service, the second request excluding parameters associated with the second radio access technology.

18. The apparatus of claim 17, wherein the instructions are further executable by the processor to cause the apparatus to: adding a public land mobile network (PLMN) associated with the first network node to a list of PLMNs that are not supported by the second radio access technology; and Based at least in part on adding the PLMN to the list, transmitting a request including parameters associated with the second radio access technology to a network node associated with the PLMN is suppressed.

19. The apparatus of claim 17, wherein the instructions are further executable by the processor to cause the apparatus to: receiving a threshold number of responses from the first network node, each response including a rejection cause as one of the preconfigured causes in the set of preconfigured causes; and Based at least in part on receiving the threshold number of responses, transmitting the second request to the first network node, the second request excluding parameters associated with the second radio access technology.

20. The apparatus of claim 19, wherein the instructions are further executable by the processor to cause the apparatus to: An indication is received that the threshold number of responses after which the UE is to transmit the second request.

21. The apparatus of claim 17, wherein determining that the second radio access technology is not supported by the first network node is based at least in part on a subscription of the UE to an operator having a relationship with a public land mobile network (PLMN) associated with the first network node.

22. The apparatus of claim 17, wherein the preconfigured cause comprises a rejection cause for which handling at the UE is undefined.

23. The apparatus of claim 17, wherein the preconfigured causes include one or more of a first cause indicating that the base station cannot derive the identity of the UE, a second cause indicating that Evolved Packet System (EPS) service is not allowed in a public land mobile network (PLMN) associated with the first network node, and a third cause indicating a protocol error.

24. The apparatus of claim 17, wherein the first request and the second request comprise an attach request or a tracking area update request.

25. An apparatus for supporting wireless communications of a first radio access technology and a second radio access technology at a user equipment (UE), the apparatus comprising: processor; a memory coupled to the processor; as well as Instructions stored in the memory and executable by the processor to cause the device to perform the following operations: establishing a first connection with a first base station according to the second radio access technology; transmitting, via the first connection with the first base station, to a first network node a first request associated with a bearer for a communication service, the first request comprising parameters associated with the second radio access technology; receiving a response from the first base station indicating that the first request is rejected, the response including a rejection cause that is one of a preconfigured cause in a preconfigured set of causes; determining, based at least in part on the rejection reason being one of the preconfigured set of reasons, that the second radio access technology is not supported by the first network node for communication with the UE; establishing a second connection with the first base station or a second base station according to the first radio access technology based at least in part on the determining; as well as Based at least in part on the determination, transmitting to the first network node or the second network node via the second connection with the first base station or the second base station a second request associated with a bearer for the communication service, the second request not including parameters associated with the second radio access technology.

26. The apparatus of claim 25, wherein the instructions are further executable by the processor to cause the apparatus to: adding a public land mobile network (PLMN) associated with the first network node to a list of PLMNs that are not supported by the second radio access technology; and Based at least in part on adding the PLMN to the list, transmitting a request including parameters associated with the second radio access technology to a network node associated with the PLMN is suppressed.

27. The apparatus of claim 25, wherein the instructions are further executable by the processor to cause the apparatus to: receiving a threshold number of responses from the first network node, each response including a rejection cause as one of the preconfigured causes in the set of preconfigured causes; and Based at least in part on receiving the threshold number of responses, transmitting the second request to the first network node or the second network node, the second request including parameters associated with the first radio access technology.

28. The apparatus of claim 27, wherein the instructions are further executable by the processor to cause the apparatus to: An indication is received that the threshold number of responses after which the UE is to transmit the second request.

29. The apparatus of claim 25, wherein determining that the second radio access technology is not supported by the first network node is based at least in part on a subscription of the UE to an operator having a relationship with a public land mobile network (PLMN) associated with the first network node.

30. The apparatus of claim 25, wherein the preconfigured cause comprises a reject cause for which handling at the UE is undefined.

31. The apparatus of claim 25, wherein the preconfigured causes include one or more of a first cause indicating that the base station cannot derive the identity of the UE, a second cause indicating that Evolved Packet System (EPS) service is not allowed in a public land mobile network (PLMN) associated with the first network node, and a third cause indicating a protocol error.

32. The apparatus of claim 25, wherein the first request and the second request comprise an attach request or a tracking area update request.

33. An apparatus for supporting wireless communications of a first radio access technology and a second radio access technology at a user equipment (UE), the apparatus comprising: means for establishing a connection with a base station according to said first radio access technology; means for transmitting, via the connection established with the base station, to a first network node, a first request associated with a bearer for a communication service, the first request comprising parameters associated with the second radio access technology; means for receiving a response from the first network node indicating that the first request is rejected, the response comprising a rejection cause that is one of a preconfigured set of causes; means for determining, based at least in part on the rejection reason being one of the preconfigured set of reasons, that the second radio access technology is not supported by the first network node for communication with the UE; as well as Means for transmitting, based at least in part on the determination, to the first network node a second request associated with a bearer for the communication service, the second request not including parameters associated with the second radio access technology.

34. The apparatus of claim 33, further comprising: means for adding a public land mobile network (PLMN) associated with the first network node to a list of PLMNs that are not supported by the second radio access technology; as well as Means for refraining from transmitting, to a network node associated with the PLMN, a request including parameters associated with the second radio access technology based at least in part on adding the PLMN to the list.

35. The apparatus of claim 33, further comprising: means for receiving a threshold number of responses from the first network node, each response including a rejection cause as one of the preconfigured causes in the set of preconfigured causes; as well as Means for transmitting the second request to the first network node based at least in part on receiving the threshold number of responses, the second request not including parameters associated with the second radio access technology.

36. The apparatus of claim 35, further comprising: Means for receiving an indication of the threshold number of responses after which the UE is to transmit the second request.

37. The apparatus of claim 33, wherein determining that the second radio access technology is not supported by the first network node is based at least in part on a subscription of the UE to an operator having a relationship with a public land mobile network (PLMN) associated with the first network node.

38. The apparatus of claim 33, wherein the preconfigured cause comprises a rejection cause for which handling at the UE is undefined.

39. The apparatus of claim 33, wherein the preconfigured causes include one or more of a first cause indicating that the base station cannot derive the identity of the UE, a second cause indicating that Evolved Packet System (EPS) service is not allowed in a public land mobile network (PLMN) associated with the first network node, and a third cause indicating a protocol error.

40. The apparatus of claim 33, wherein the first request and the second request comprise an attach request or a tracking area update request.

41. An apparatus for supporting wireless communications of a first radio access technology and a second radio access technology at a user equipment (UE), the apparatus comprising: means for establishing a first connection with a first base station according to the second radio access technology; means for transmitting, via the first connection with the first base station, to a first network node, a first request associated with a bearer for a communication service, the first request comprising parameters associated with the second radio access technology; means for receiving a response from the first base station indicating that the first request is rejected, the response comprising a rejection cause that is one of a preconfigured set of causes; means for determining, based at least in part on the rejection reason being one of the preconfigured set of reasons, that the second radio access technology is not supported by the first network node for communication with the UE; means for establishing a second connection with the first base station or a second base station according to the first radio access technology based at least in part on the determining; as well as Means for transmitting, based at least in part on the determination, to the first network node or the second network node via the second connection with the first base station or the second base station, a second request associated with a bearer for the communication service, the second request not including parameters associated with the second radio access technology.

42. The apparatus of claim 41, further comprising: means for adding a public land mobile network (PLMN) associated with the first network node to a list of unsupported PLMNs for the second radio access technology; as well as Means for refraining from transmitting, to a network node associated with the PLMN, a request including parameters associated with the second radio access technology based at least in part on adding the PLMN to the list.

43. The apparatus of claim 41, further comprising: means for receiving a threshold number of responses from the first network node, each response including a rejection cause as one of the preconfigured causes in the set of preconfigured causes; as well as Means for transmitting the second request to the first network node or the second network node based at least in part on receiving the threshold number of responses, the second request comprising parameters associated with the first radio access technology.

44. The apparatus of claim 43, further comprising: Means for receiving an indication of the threshold number of responses after which the UE is to transmit the second request.

45. The apparatus of claim 41, wherein determining that the second radio access technology is not supported by the first network node is based at least in part on a subscription of the UE to an operator having a relationship with a public land mobile network (PLMN) associated with the first network node.

46. ​​The apparatus of claim 41, wherein the preconfigured cause comprises a reject cause for which handling at the UE is undefined.

47. The apparatus of claim 41, wherein the preconfigured causes include one or more of a first cause indicating that the base station cannot derive the identity of the UE, a second cause indicating that Evolved Packet System (EPS) service is not allowed in a public land mobile network (PLMN) associated with the first network node, and a third cause indicating a protocol error.

48. The apparatus of claim 41, wherein the first request and the second request comprise an attach request or a tracking area update request.

49. A non-transitory computer readable medium storing code for supporting wireless communications of a first radio access technology and a second radio access technology at a user equipment (UE), the code comprising instructions executable by a processor for: establishing a connection with a base station according to the first radio access technology; transmitting, via the connection established with the base station, to a first network node, a first request associated with a bearer for a communication service, the first request comprising parameters associated with the second radio access technology; receiving a response from the first network node indicating that the first request is rejected, the response including a rejection reason that is one of a preconfigured set of reasons; determining, based at least in part on the rejection reason being one of the preconfigured set of reasons, that the second radio access technology is not supported by the first network node for communication with the UE; as well as Based at least in part on the determination, transmitting to the first network node a second request associated with a bearer for the communication service, the second request excluding parameters associated with the second radio access technology.

50. The non-transitory computer readable medium of claim 49, wherein the instructions are further executable to: adding a public land mobile network (PLMN) associated with the first network node to a list of PLMNs that are not supported by the second radio access technology; and Based at least in part on adding the PLMN to the list, transmitting a request including parameters associated with the second radio access technology to a network node associated with the PLMN is suppressed.

51. The non-transitory computer readable medium of claim 49, wherein the instructions are further executable to: receiving a threshold number of responses from the first network node, each response including a rejection cause as one of the preconfigured causes in the set of preconfigured causes; and Based at least in part on receiving the threshold number of responses, transmitting the second request to the first network node, the second request excluding parameters associated with the second radio access technology.

52. The non-transitory computer readable medium of claim 51, wherein the instructions are further executable to: An indication is received that the threshold number of responses after which the UE is to transmit the second request.

53. The non-transitory computer-readable medium of claim 49, wherein determining that the second radio access technology is not supported by the first network node is based at least in part on a subscription of the UE to an operator having a relationship with a public land mobile network (PLMN) associated with the first network node.

54. The non-transitory computer-readable medium of claim 49, wherein the preconfigured cause comprises a rejection cause for which handling at the UE is undefined.

55. The non-transitory computer-readable medium of claim 49, wherein the preconfigured causes include one or more of a first cause indicating that the base station cannot derive the identity of the UE, a second cause indicating that Evolved Packet System (EPS) service is not allowed in a public land mobile network (PLMN) associated with the first network node, and a third cause indicating a protocol error.

56. The non-transitory computer readable medium of claim 49, wherein the first request and the second request comprise an attach request or a tracking area update request.

57. A non-transitory computer readable medium storing code for supporting wireless communications of a first radio access technology and a second radio access technology at a user equipment (UE), the code comprising instructions executable by a processor for: establishing a first connection with a first base station according to the second radio access technology; transmitting, via the first connection with the first base station, to a first network node a first request associated with a bearer for a communication service, the first request comprising parameters associated with the second radio access technology; receiving a response from the first base station indicating that the first request is rejected, the response including a rejection cause that is one of a preconfigured cause in a preconfigured set of causes; determining, based at least in part on the rejection reason being one of the preconfigured set of reasons, that the second radio access technology is not supported by the first network node for communication with the UE; establishing a second connection with the first base station or a second base station according to the first radio access technology based at least in part on the determining; as well as Based at least in part on the determination, transmitting to the first network node or the second network node via the second connection with the first base station or the second base station a second request associated with a bearer for the communication service, the second request not including parameters associated with the second radio access technology.

58. The non-transitory computer readable medium of claim 57, wherein the instructions are further executable to: adding a public land mobile network (PLMN) associated with the first network node to a list of PLMNs that are not supported by the second radio access technology; and Based at least in part on adding the PLMN to the list, transmitting a request including parameters associated with the second radio access technology to a network node associated with the PLMN is suppressed.

59. The non-transitory computer readable medium of claim 57, wherein the instructions are further executable to: receiving a threshold number of responses from the first network node, each response including a rejection cause as one of the preconfigured causes in the set of preconfigured causes; and Based at least in part on receiving the threshold number of responses, transmitting the second request to the first network node or the second network node, the second request including parameters associated with the first radio access technology.

60. The non-transitory computer readable medium of claim 59, wherein the instructions are further executable to: An indication is received that the threshold number of responses after which the UE is to transmit the second request.

61. The non-transitory computer-readable medium of claim 57, wherein determining that the second radio access technology is not supported by the first network node is based at least in part on a subscription of the UE to an operator having a relationship with a public land mobile network (PLMN) associated with the first network node.

62. The non-transitory computer-readable medium of claim 57, wherein the preconfigured cause comprises a rejection cause for which handling at the UE is undefined.

63. A non-transitory computer-readable medium as described in claim 57, wherein the preconfigured causes include one or more of a first cause indicating that the base station cannot derive the identity of the UE, a second cause indicating that Evolved Packet System (EPS) service is not allowed in a public land mobile network (PLMN) associated with the first network node, and a third cause indicating a protocol error.

64. The non-transitory computer readable medium of claim 57, wherein the first request and the second request comprise an attach request or a tracking area update request.

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