Fallback and recovery between radio access technologies

Abstract

Embodiments of apparatus and methods for fallback processing are disclosed. In one example, a method for fallback processing may include operating a user equipment with a fifth generation (5G) wireless access technology. The method may also include keeping second generation (2G) and third generation (3G) physical layer components in a hot state. The method may also include keeping 2G and 3G layer 2 components in an inactive state.

Description

Background Art

[0001] Embodiments of the present disclosure relate to apparatus and methods for wireless communications.

[0002] Wireless communication systems are widely deployed to provide a variety of telecommunication services, such as telephone, video, data, messaging, and broadcasting. In cellular communications, such as the fourth generation (4th-generation, 4G) long term evolution (long term evolution, LTE) and the fifth generation (5th-generation, 5G) new radio (new radio, NR), the third generation partnership project (3rd generation partnership project, 3GPP) defines a protocol stack that includes a set of layers collectively referred to as layer 2: from high to low in the stack, the packet data convergence protocol (packet data convergence protocol, PDCP) layer, the radio link control (radio link control, RLC) layer, and the medium access control (medium access control, MAC). These layers are located above the physical layer (physical layer, PHY) in the stack. PHY is also called layer 1. If the user equipment is capable of operating with various radio access technologies, these layer 2 and layer 1 circuits can exist in multiple versions in a given user equipment. Summary of the invention

[0003] Embodiments of apparatus and methods for fallback processing are disclosed herein.

[0004] In one example, a method for fallback processing may include operating a user equipment with a fifth generation (5G) radio access technology. The method may also include keeping second-generation (2G) and third-generation (3G) physical layer components in a warm state. The method may also include keeping 2G and 3G layer 2 (layer 2, also referred to as layer 2) components in an inactive state.

[0005] In another example, a method for fallback processing may include operating a user equipment with a fifth generation (5G) wireless access technology. The method may also include switching to a second generation (2G) or third generation (3G) wireless access technology only when out of service (OOS) coverage or an Internet protocol (IP) multimedia subsystem (IMS) failure occurs.

[0006] In another example, a method for fallback processing may include operating a user equipment with a fifth generation (5G) wireless access technology. The method may also include determining a likelihood of falling back to at least one of a second generation (2G) or a third generation (3G) wireless access technology. The method may also include falling back to a 2G or 3G wireless access technology only when the likelihood exceeds a threshold.

[0007] In another example, a method for fallback processing may include operating a user equipment with a fifth generation (5G) radio access technology. The method may also include falling back to at least one of a second generation (2G), a third generation (3G), or a fourth generation (4G) radio access technology. The method may also include performing only an idle mode search for a 5G radio access technology system when attempting to return from a 2G, 3G, or 4G radio access technology to a 5G radio access technology.

[0008] In another example, a device for fallback processing may include at least one processor and at least one memory including computer program code. The at least one memory and computer program code may be used to, together with the at least one processor, cause the device to operate at least a fifth generation (5G) wireless access technology. The at least one memory and computer program code may also be used to, together with the at least one processor, cause the device to at least keep second generation (2G) and third generation (3G) physical layer components in a hot state. The at least one memory and computer program code may also be used to, together with the at least one processor, cause the device to at least keep 2G and 3G layer 2 components in an inactive state.

[0009] In another example, a device for fallback processing may include at least one processor and at least one memory including computer program code. The at least one memory and computer program code may be used to cause the device to operate the device with at least a fifth generation (5G) wireless access technology together with the at least one processor. The at least one memory and computer program code may also be used to cause the device to switch to a second generation (2G) or third generation (3G) wireless access technology together with the at least one processor at least only when there is no service (OOS) coverage or an Internet Protocol (IP) multimedia subsystem (IMS) failure.

[0010] In another example, a device for fallback processing may include at least one processor and at least one memory including computer program code. The at least one memory and computer program code may be used to, together with the at least one processor, cause the device to operate at least with a fifth generation (5G) wireless access technology. The at least one memory and computer program code may also be used to, together with the at least one processor, cause the device to at least determine the possibility of falling back to at least one of a second generation (2G) or a third generation (3G) wireless access technology. The at least one memory and computer program code may also be used to, together with the at least one processor, cause the device to fall back to a 2G or 3G wireless access technology at least only when the possibility exceeds a threshold.

[0011] In another example, a device for fallback processing may include at least one processor and at least one memory including computer program code. At least one memory and computer program code may be used to operate the device with at least one processor at least in a fifth generation (5G) wireless access technology. At least one memory and computer program code may also be used to cause the device to fall back to at least one of the second generation (2G), third generation (3G), or fourth generation (4G) wireless access technologies together with at least one processor. At least one memory and computer program code may also be used to cause the device to perform only an idle mode search for a 5G wireless access technology system when attempting to return to a 5G wireless access technology from a 2G, 3G, or 4G wireless access technology together with at least one processor. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The accompanying drawings, which are incorporated herein and form a part of the specification, illustrate embodiments of the present disclosure and, together with the description, further serve to explain the principles of the present disclosure and enable those skilled in the relevant art to make and use the present disclosure.

[0013] Figure 1 An overlay diagram involving mixed overlay types consistent with certain embodiments of the present disclosure is shown.

[0014] Figure 2 A UE modem stack consistent with certain embodiments of the present disclosure is shown.

[0015] Figure 3 A state diagram showing an overview of certain embodiments of the present disclosure.

[0016] Figure 4 A first alternative scheme for non-standalone user equipment, namely 5G / 4G minimized fallback and recovery, according to certain embodiments of the present disclosure is shown.

[0017] Figure 5A second alternative scheme for non-standalone user equipment according to certain embodiments of the present disclosure, namely 5G / 4G fast optimized fallback and recovery, is shown.

[0018] Figure 6 A UE modem stack consistent with certain embodiments of the present disclosure is shown.

[0019] Figure 7 A state diagram showing an overview of certain embodiments of the present disclosure.

[0020] Figure 8 5G minimized fallback and recovery for 5G standalone user equipment according to certain embodiments is shown.

[0021] Fig. 9 5G fast optimized fallback and recovery for 5G standalone user equipment is shown in accordance with certain embodiments.

[0022] Fig.10 Nodes according to some embodiments are shown.

[0023] Fig.11 A network including a plurality of nodes is shown in accordance with some embodiments.

[0024] Embodiments of the present disclosure will be described with reference to the accompanying drawings. DETAILED DESCRIPTION

[0025] Although specific configurations and arrangements are described, it should be understood that this is for illustrative purposes only. Those skilled in the relevant art will recognize that other configurations and arrangements may be used without departing from the spirit and scope of the present disclosure. It will be apparent to those skilled in the relevant art that the present disclosure may also be used in various other applications.

[0026] Note that references in the specification to "one embodiment," "an embodiment," "an example embodiment," "some embodiments," "certain embodiments," etc., indicate that the described embodiments may include a particular feature, structure, or characteristic, but not every embodiment necessarily includes the particular feature, structure, or characteristic. Furthermore, such phrases do not necessarily refer to the same embodiment. Furthermore, when a particular feature, structure, or characteristic is described in conjunction with an embodiment, whether or not explicitly described, it is within the knowledge of a person skilled in the relevant art to implement such feature, structure, or characteristic in conjunction with other embodiments.

[0027] Typically, a term can be understood at least in part from usage in context. For example, the term "one or more" as used herein can be used to describe any feature, structure, or characteristic in a singular sense, or can be used to describe a combination of features, structures, or characteristics in a plural sense, which depends at least in part on the context. Similarly, terms such as "one," "an," or "the" can be understood to convey singular usage or to convey plural usage, which depends at least in part on the context. In addition, the term "based on" can be understood to not necessarily be intended to convey a set of exclusive factors, but can allow for the presence of other factors that are not necessarily explicitly described, which also depends at least in part on the context.

[0028] Various aspects of the wireless communication system will now be described with reference to various apparatus and methods. These apparatus and methods will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, modules, units, components, circuits, steps, operations, processes, algorithms, etc. (collectively referred to as "elements"). These elements can be implemented using electronic hardware, firmware, computer software, or any combination thereof. Whether these elements are implemented as hardware, firmware, or software depends on the specific application and the design constraints imposed on the overall system.

[0029] The technology described herein can be used in various wireless communication networks, such as code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems and other networks. The terms "network" and "system" are often used interchangeably. A CDMA network can implement a radio access technology (RAT), such as universal terrestrial radio access (UTRA), evolved UTRA (Evolved UTRA, E-UTRA), CDMA 2000, etc. A TDMA network can implement a RAT, such as global system for mobile communications (GSM). An OFDMA network can implement a RAT, such as LTE or NR. The technology described herein can be used for the above-mentioned wireless networks and RATs as well as other wireless networks and RATs.

[0030] Figure 1 An overlay diagram involving mixed overlay types consistent with certain embodiments of the present disclosure is shown.

[0031] like Figure 1 As shown, in a typical fifth generation (5G) cellular deployment, a typical operator may adopt a 5G system in a small concentrated hot coverage area where 5G specific low latency and high throughput applications are expected to exist. Such coverage areas may be overlaid with a traditional long term evolution (LTE) fourth generation (4G) system with a wider coverage area. In addition, these areas are usually overlaid with a traditional third generation (3G) / second generation (2G) system to provide seamless coverage and allow fallback when any user equipment (UE) moves out of the coverage of the 5G or 4G system.

[0032] A UE that can operate with multiple radio access technologies (RATs) (e.g., 5G, 4G, 3G, 2G) can use multi-RAT system selection search to acquire a suitable and verified system. Once a 5G system is acquired and in idle mode, the UE will perform periodic measurements on neighboring cells to evaluate whether it needs to reselect the same or different RAT on another cell with better coverage.

[0033] If a lower technology RAT (e.g. 3G) is reselected, the UE may also perform periodic measurements on neighboring cells to see if the UE can trigger reselection to a higher technology RAT (e.g. 5G) as soon as possible.

[0034] Ping-pong from 5G / 4G to legacy RAT and back to 5G / 4G systems may occur at the boundary between 5G and legacy system coverage.

[0035] To address mixed coverage, 5G / 4G non-stand-alone (NSA) UEs may typically have legacy 3G, 2G protocols, L2, and L1 stacks that will not remain inactive. Instead, these wireless systems may be prepared to perform periodic measurements on neighboring 3G and 2G base stations. When the UE moves out of the coverage of the 5G / 4G network and when the 3G or 2G signal strength exceeds the threshold of the current 5G / 4G system, the UE can reselect to the legacy 3G or 2G network.

[0036] A 5G-centric UE can be configured to stay in the 5G / 4G system as much as possible and only fall back to the legacy 3G / 2G system when absolutely necessary with minimal complexity and power.

[0037] This approach may require complex logic to keep all multi-RAT stacks (5G, 4G, 3G, 2G) inactive to facilitate inter-RAT reselection between RATs. In addition, this approach may require complex multi-subscriber identity module (SIM) logic to facilitate interworking between 5G, 4G, 3G, 2G.

[0038] Furthermore, this approach may perform too many measurements, resulting in inefficient use of resources at the physical (PHY) layer. Excessive measurements may also require increased power in the UE and may cause interference in the network.

[0039] In this approach, there may also be complex arbitration for sharing radio frequency (RF) resources between multiple RATs. A lot of software logic and code space may be required for multi-RAT protocol stack control. In addition, complex issues may lead to non-optimal fallback to legacy systems instead of staying on 5G as long as possible.

[0040] In certain embodiments of the present disclosure, a set of simple and minimal 5G-centric user equipment (UE) fallback and recovery schemes from 5G / 4G to the legacy 3GPP protocol stack including 3G and 2G are shown. Certain embodiments of the method can use less power and can eliminate complex multi-RAT arbitration logic by triggering fallback from 5G / 4G to the legacy system only when absolutely necessary.

[0041] A simplified and minimal set of 5G-centric user equipment (UE) fallback and recovery scenarios from 5G / 4G non-standalone (NSA) or 5G standalone (SA) to the legacy 3GPP 3G / 2G protocol stack are also explained.

[0042] At least five different aspects of certain embodiments may be provided in detail below. A first aspect of certain embodiments relates to keeping the traditional protocol stack of the user device in a cold state when the user device is in pure 5G / 4G (5G / 4G only) mode, non-independent. In this regard (described in more detail below), if a 5G-centric UE acquires a 5G or 4G network to obtain maximum performance for data throughput and latency, it may be powered on to enter a "5G4G_Only" NSA mode. Traditional 3G, 2G protocol stacks may all be inactive and in a "COLD" state. The 2G and 3G PHY layers may be powered on and enter a low-power "hot" state.

[0043] A second aspect of certain embodiments relates to a first fallback scheme for a user equipment in a pure 5G / 4G mode (which may also be described as a non-standalone mode). Figure 4 In this regard (described in more detail below), a 5G-centric NSAUE may transition to a legacy system through a simplified and minimized path only in the event of out-of-service (OOS) coverage or Internet Protocol (IP) Multimedia Subsystem (IMS) failure. The legacy 3G / 2G PHY layer may be started in a hot start, and the 3G / 2G protocol stack may be activated from a cold start.

[0044] A third aspect of certain embodiments relates to a second fallback scheme for a user equipment in pure 5G / 4G mode. In this aspect (described in more detail below), an alternative path for falling back to a legacy system is provided, using a scoring function to evaluate the likelihood of the fallback path occurring, for example taking into account the location of neighboring legacy base stations and the current UE receiving signal.

[0045] A fourth aspect of certain embodiments relates to resuming 5G / 4G without performing a connection state handover. In this aspect (described in more detail below), in order to revert to 5G / 4G, the method may include performing only an idle search by measuring and acquiring a higher 5G / 4G system without performing a connection state handover.

[0046] A fifth aspect of certain embodiments relates to a pure 5G standalone user equipment. This can be seen as extending the above aspects to a pure 5G standalone (SA) or pure 5G and higher version UE.

[0047] As mentioned above, Figure 1 An overlay diagram involving a hybrid overlay type consistent with certain embodiments of the present disclosure is shown. More specifically, Figure 1 An example of a 5G deployment with 3GPP legacy LTE, 4G, 3G, 2G coverage is shown.

[0048] One goal for a 5G-centric UE may be to stay in the 5G / 4G system as much as possible, and only fall back to the legacy 3G / 2G system when absolutely necessary with minimal complexity and power. Certain embodiments of the present disclosure may provide these and other benefits and advantages.

[0049] As described above, certain embodiments may provide a simplified and minimal set of 5G-centric UE fallback and recovery solutions from 5G / 4G NSA or 5G SA to the legacy 3GPP 3G / 2G protocol stack.

[0050] Figure 2 A UE modem stack consistent with certain embodiments of the present disclosure is shown. In this 5G-centric modem, the 5G / 4G protocol stack and PHY layer are active most of the time, with the goal of staying in pure 5G / 4G mode (NSA) as much as possible. In this mode, 5G and 4G systems interoperate according to the 3GPP IRAT protocol.

[0051] In addition, a global positioning system (GPS) engine that provides accurate location data of the UE allows the UE to calculate the distance to the nearest neighboring traditional base station. The location information of the traditional base station can be broadcast to the UE in a 5G / 4G overhead message. The GPS engine can remain in active mode. It is understood that the GPS engine can broadly include any suitable positioning engine, such as Galileo, global navigation satellite system (GLONASS), Beidou navigation system, etc.

[0052] The traditional 3G / 2G protocol stack is in cold mode or inactive mode. The corresponding 3G / 2G PHY layer is powered on but enters a low power mode or hot state. The protocol stack and physical layer can be considered in low power mode when they are receiving current but the current level is lower than the level during typical active operation (due to some components being inactive, etc.).

[0053] Figure 3 A state diagram showing an overview of certain embodiments of the present disclosure. When powered on, the UE may attempt to acquire a 5G or 4G system. Once successful, the UE may enter a pure 5G / 4G mode (NSA) in which only the 5G or 4G protocol stack and PHY layer are active. The legacy 3G / 2G protocol stack may be in an inactive or cold state, where the respective PHY layers of these protocol stacks may be powered on but in a low power or hot state.

[0054] At 5G / 4G and 3G / 2G cell edges, the UE may have to fall back to these legacy RATs. To do this effectively, the first option (5G / 4G minimized fallback and recovery) or the second option (5G / 4G fast optimized fallback and recovery) can be selected.

[0055] In the first alternative, if the UE moves out of 5G / 4G coverage, or if an IMS failure occurs, the UE may transition to 3G / 2G mode. In these legacy modes, the UE may periodically scan 5G and 4G systems to recover during an idle search. The idle search may include periodic measurements obtained by periodically scanning for higher systems. Connection switching may not be performed.

[0056] In the second alternative, the UE may use a scoring function to evaluate the likelihood of a fallback path before actually performing reselection to the legacy RAT. The scoring function may take into account the location of neighboring legacy base stations and the current signal received by the UE. Similar to the first alternative, a simplified approach may be used to recover to 5G / 4G as quickly as possible by performing an idle search. Connection switching may not be performed.

[0057] Figure 4 A first alternative scheme for non-standalone user equipment, namely 5G / 4G minimized fallback and recovery, according to certain embodiments of the present disclosure is shown.

[0058] like Figure 4 As shown, at 410, the UE can be in a pure 5G / 4G non-standalone mode after powering on and acquiring a 4G or 5G system. In this mode, the UE can perform 5G / 4G interworking according to the 3GPP inter-RAT (IRAT) protocol. The traditional 3G / 2G protocol stack can be in a cold state, and the PHY layer of these protocol stacks can be powered on but enter a low-power hot state.

[0059] At 420, the user equipment may periodically check whether one of a limited number of fallback conditions is met. Alternatively, the occurrence of one of a limited number of fallback conditions may trigger the UE to take action. The limited number of conditions may be, for example, the presence of a no service condition or an IMS failure, such as an IMS registration failure or an IMS call setup failure.

[0060] At 430, assuming the fallback condition is met, the UE may activate the 3G / 2G protocol stack and perform system selection scanning for the 3G / 2G system closest to the UE. During activation, the UE may activate the 3G / 2G protocol stack via a cold start, and the PHY layer may be activated via a hot start.

[0061] At 440, the UE may determine whether a valid 3G / 2G has been acquired. If a valid 3G / 2G has been acquired, at 450, the UE may operate in 3G / 2G mode until a 5G / 4G system is found and the process returns to 410. Otherwise, at 460, the user equipment may perform an OOS scan for any available system (e.g., 5G, 4G, 3G, 2G) at any time.

[0062] When attempting to acquire a 3G / 2G RAT, the user equipment may use the activated legacy 3G / 2G system selection algorithm. The UE may use the information of neighboring systems in previous 5G / 4G broadcast overhead signaling messages and location information obtained from GPS data to scan for the selected 3G or 2G base station closest to the UE. Once a 3G or 2G system is acquired, the system may be verified so that the UE may transition to 3G / 2G mode.

[0063] After entering 3G / 2G mode at 450, the user equipment may periodically search for a neighboring strong 5G / 4G system and may perform measurements during idle search so that the user equipment may reselect back to a higher 5G / 4G system as quickly as possible. No connection mode switching is required, so connection mode switching may be avoided in this method.

[0064] Figure 5A second alternative for non-standalone user equipment according to certain embodiments of the present disclosure is shown, namely 5G / 4G fast optimized fallback and recovery. The method includes Figure 4 Many of the same features shown, but with the addition of a fast fallback path.

[0065] As in Figure 4 In 420, the user equipment may determine whether there is an IMS failure or OOS condition. If so, the process may be as follows: Figure 4 Said, at 430, proceeds by activating the 3G / 2G protocol stack.

[0066] On the other hand, Figure 5 In the example, there is an additional path. The additional path begins at 510, determining whether to perform a fallback evaluation. In this path (as will be discussed in more detail below), the UE evaluates the fallback possibility and performs reselection only when the fallback possibility is high enough to justify the transition.

[0067] After powering on and acquiring the 5G / 4G system and entering the pure 5G / 4G mode at 410 (e.g. Figure 4 After the UE measures the 5G or 4G received power P5, if the power is less than the specified threshold P5min for a specified time interval T5min, then at 510, the 5G / 4G protocol stack may be triggered to perform an evaluation of the fallback probability.

[0068] At 520, the user equipment may calculate a fallback possibility score. In other words, when the received power is below the threshold for too long to trigger a fallback evaluation, for example, when the UE is at the cell edge of 5G coverage and legacy system coverage, the UE may check whether the UE may need to fall back to the 3G / 2G system. The UE may evaluate its fallback possibility by calculating the fallback possibility score at 520.

[0069] The fallback possibility score S_53 from 5G / 4G to 3G / 2G can be calculated as follows: Where P5 is the received signal strength of the 5G / 4G system, as mentioned above, I5 is the received interference of the 5G / 4G system, and D 532 is the distance from the UE to the nearest 3G or 2G base station, B5 is the average data buffer queue size at the UE, and L5 is the minimum delay value for packet data applications at the UE.

[0070] The remaining factors k1, k2, k3, k4, k5 can be adjustable factors of the scoring function for each variable input. Note that D 532 The distance (from the UE to the nearest 3G or 2G base station) can be derived using the UE's GPS data and location data in the 3GPP overhead information about the coordinates of the legacy RAT base stations.

[0071] At 530, the user equipment determines whether S_53 is greater than a threshold value S_53min. If so, it is considered that the possibility of needing to roll back is high. Therefore, the user equipment can continue as described above at 430. Otherwise, the user equipment can return to 410.

[0072] When the probability is higher than a threshold, fallback from 5G / 4G to 3G / 2G system can be triggered before the UE has no service on the 5G / 4G system.

[0073] By ensuring that the UE is very likely to need to perform a fallback, this scheme can avoid some unnecessary ping-ponging to and from lower systems.

[0074] The above aspects are directed to user equipment scenarios in non-standalone mode. Certain embodiments may also or optionally be applied to 5G-centric UEs operating in a pure 5G (SA mode) state. As described in the following non-limiting examples, the above methods can be extended to / from traditional 4G, 3G, 2G system fallback and recovery schemes.

[0075] Figure 6 A UE modem stack consistent with certain embodiments of the present disclosure is shown. Figure 6 More specifically, a modem stack that may be in SA mode is shown. In this 5G-centric modem, the 5G protocol stack and PHY layers may be active most of the time, with the goal of staying in 5G mode as much as possible. The 4G protocol stack as well as the 3G / 2G protocol stack may all be in cold or inactive mode. The corresponding 4G and 3G / 2G PHY layers are powered on but enter a low power mode or hot state.

[0076] Figure 7 A state diagram showing an overview of certain embodiments of the present disclosure. More specifically, Figure 7 An overview of some additional aspects of the present disclosure is provided, which may be viewed as extensions of previously described aspects.

[0077] like Figure 7 As shown, when the UE is powered on, the US can attempt to acquire the 5G system. Once successful, the UE can enter a pure 5G mode, in which only the 5G protocol stack and PHY layer are active. The traditional 4G / 3G / 2G protocol stacks can be in an inactive or cold state, and the respective PHY layers of these protocol stacks can be powered on but in a low power or hot state.

[0078] At the 5G and 4G / 3G / 2G cell edges, the UE may have to fall back to these legacy RATs. To do this effectively, the above-mentioned minimized fallback and recovery paths or the 5G fast optimized fallback and recovery paths can be selected by design.

[0079] According to the first alternative, if the UE moves out of coverage, or if an IMS failure occurs, the UE can switch to 4G mode or directly to 3G / 2G mode, depending on which system is in the search. The user equipment can prioritize 4G radio access technology over 3G / 2G radio access technology. In these legacy modes, the UE periodically scans for 5G systems to recover during idle searches. In some embodiments, no connection mode switching is performed.

[0080] According to the second alternative, the UE can use a scoring function instead of relying solely on OOS and IMS failures to evaluate the likelihood of a fallback path before actually performing a reselection to the legacy RAT. The scoring function can take into account the location of the neighboring legacy base stations and the signals currently received at the UE. Once a fallback occurs, the UE can resume using the idle search process to return to the 5G system as soon as possible. Figure 7 As shown, the UE can first return to 4G mode from 2G / 3G mode based on coverage availability.

[0081] In 3G / 2G, idle search may involve periodic scanning and measurement of higher systems (including 4G and 5G). Similarly, in 4G mode, idle search may involve periodic scanning and measurement of higher systems (i.e., 5G systems). Although these examples consider 5G as the highest level of the system (because it is the highest level currently in widespread use), these same principles can also be applied in a similar manner to any subsequent wireless access technology.

[0082] Figure 8 5G minimized fallback and recovery for 5G standalone user equipment according to certain embodiments is shown. After acquiring the 5G system, at 810, the 5G-centric UE can be powered on in pure 5G mode (also known as standalone mode). Traditional 4G / 3G / 2G protocol stacks may be in a cold state, and the PHY layers of these protocol stacks can be powered on but enter a low-power hot state. When no service coverage, IMS registration failure, or IMS call establishment failure is detected at 420, at 820, the UE can activate the 4G LTE protocol stack. The UE can activate the 4G protocol stack through a cold start, and can activate the PHY layer through a hot start. At the same time, at this time, the 3G / 2G protocol stack can remain in a cold state, and the PHY layers of these protocol stacks can continue to be powered on but remain in a low-power hot state.

[0083] The 4G LTE system selection mechanism may be activated and the selectable 4G base station closest to the UE may be scanned. Information about neighboring systems may be broadcast in 5G overhead signaling messages. At the UE, the location of the nearest 4G base station may also be obtained.

[0084] Once the 4G system is acquired at 830, the 4G system may be verified so that the UE may transition to 4G mode at 840. In this mode, the UE may periodically search for a neighboring strong 5G system and perform measurements during idle search so that the user equipment may reselect back to a higher system as quickly as possible and return to 810. All connection mode switching may be avoided.

[0085] If the 4G system cannot be acquired at 830, or cannot be verified after acquisition, the 3G / 2G protocol stack can be activated at 430 as in the previous example. The user example can activate the 3G / 2G protocol stack through cold start, and the PHY layer can be activated through hot start. The UE can use the information of the neighboring system in the previous 5G overhead signaling message and the location information obtained from the GPS data to scan for a specific 3G or 2G base station closest to the UE. Once the 3G or 2G system is acquired at 440, the acquired system can be verified so that the UE can switch to 3G / 2G mode at 450.

[0086] In 3G / 2G mode, as in the previous example, the UE may periodically search for a neighboring strong 5G / 4G system and may perform measurements during idle search so that the user equipment may reselect back to a higher 5G / 4G system as quickly as possible. Connection mode switching may not be performed.

[0087] Fig. 9 5G fast optimized fallback and recovery for 5G standalone user equipment according to certain embodiments is shown. Figure 5 Relative to Figure 4 , Fig. 9 Relative to Figure 8 Added a quick fallback option based on execution evaluation.

[0088] like Fig. 9 As shown, an alternative path is provided for 5G fast optimized fallback, where the UE can perform reselection only when the probability of fallback (also called down handover) is high enough to justify the transition.

[0089] After powering up and acquiring the 5G system and entering pure 5G mode at 810, the UE may measure its 5G received power P5. If the power is less than a specified threshold P5min for a specified time interval T5min, then at 910, the 5G protocol stack may be triggered to perform an evaluation of the fallback probability.

[0090] The UE may evaluate its likelihood of fallback (also referred to as down-handover) by calculating a fallback likelihood score at 920. This calculation may be similar to the above calculation. However, as opposed to falling back to 3G / 2G, a separate calculation may be performed for falling back to 4G.

[0091] At 930, the user equipment may perform 5G to 4G fallback possibility scoring. The UE may evaluate its fallback possibility by calculating a 5G to 4G fallback possibility score S_54 as follows: Where P5 is the received signal strength of the 5G system at the user equipment, I5 is the received interference of the 5G system, and D 54 is the distance from the UE to the nearest candidate 4G base station, B5 is the average data buffer queue size at the user equipment, and L5 is the minimum delay value for packet data applications at the user equipment.

[0092] The remaining factors k6, k7, k8, k9, k10 can be adjustable factors of the scoring function for each variable input. Note that D 54 The distance (from the UE to the nearest 4G base station) can be derived using the UE's GPS data and location data in the 3GPP overhead information about the coordinates of the legacy RAT base stations.

[0093] If S_54>S_54min, then the possibility of falling back from 5G to a nearby 4G system is reasonable, and the fallback from 5G to 4G system can be triggered before the UE is out of service on the 5G system. By ensuring that the UE is most likely to need to perform a fallback, this scheme avoids unnecessary fallbacks to lower systems.

[0094] At 820, as described above, once the fallback is triggered, the 4G protocol stack can be activated immediately, and the 4G system selection can be triggered to scan for valid 4G systems starting from the nearest 4G base station. The user equipment can activate the 4G protocol stack through a cold start, and the PHY layer can be activated through a hot start.

[0095] If a 5G packet data session is ongoing when fallback occurs, the packet data session can be forced into dormant mode, in which the IP data stack layer context is preserved until a new 4G RAT is acquired.

[0096] If it is determined at 830 that 4G is acquired and verified, then at 840, the user equipment can be switched to 4G mode. In this mode, the UE periodically scans for higher or better systems (5G) during idle search. Once any 5G system is found, the UE can revert to the higher system. In some embodiments, connection mode switching is not performed.

[0097] If the 5G to 4G scoring function S_54 criteria is not met, or if the acquired 4G system is not verified, the UE may check whether the UE should attempt to fall back to the 3G / 2G system if the UE is at the cell edge of such a legacy system.

[0098] The 5G to 3G / 2G fallback possibility score S_53 can be calculated as explained above. If at 940, S_53 is greater than the threshold S_53min, the possibility of falling back from 5G to a nearby 3G / 2G system can be considered reasonable, and the fallback from 5G to 3G / 2G system can be triggered before the UE is out of service on the 5G system. By ensuring that the UE is most likely to need to perform a fallback, the scheme avoids unnecessary transfers to lower systems.

[0099] Once the conditions are met, at 430 , the 3G / 2G protocol stack may be immediately activated, and the 3G / 2G system selection algorithm may be triggered to scan for valid 3G / 2G systems starting from the nearest legacy base station.

[0100] At the same time, the UE can periodically search for neighboring strong 5G / 4G systems and perform measurements during idle search, so that the UE can reselect back to a higher 5G / 4G system as quickly as possible without the need for connection mode switching.

[0101] Certain embodiments provide various benefits and / or advantages. For example, certain embodiments may trigger a fallback from 5G / 4G to a legacy 3G / 2G system through two methods referred to as 5G / 4G minimized fallback and recovery and 5G / 4G fast optimized fallback and recovery, respectively, thereby eliminating complex multi-RAT arbitration logic. Therefore, certain embodiments may allow 5G-centric UEs to stay in 5G / 4G (NSA) systems as much as possible and only fall back to traditional 3G / 2G systems with minimal complexity and power when absolutely necessary. In addition, certain embodiments are also applicable to UEs configured to be more preferentially in pure 5G (SA) to fall back from pure 5G to traditional 4G and 3G / 2G systems. Similarly, 5G minimized fallback and recovery and 5G fast optimized fallback and recovery provide mechanisms to achieve such benefits and / or advantages.

[0102] Therefore, more generally, some embodiments provide a practical solution with minimal software complexity. In addition, some embodiments eliminate the complex multi-RAT arbitration logic and code space between multiple RAT protocol stacks of 5G, 4G, 3G, and 2G. In addition, some embodiments eliminate the complex multi-SIM logic to facilitate interworking between 5G, 4G, 3G, and 2G. In addition, some embodiments eliminate the complex arbitration of shared RF resources between multiple RATs.

[0103] Furthermore, certain embodiments eliminate multiple legacy 3G / 2G RATs being in a non-inactive state for inter-RAT reselection. Furthermore, certain embodiments eliminate inefficient resource usage caused by excessive measurements at the PHY layer. Certain embodiments prevent 5G-centric UEs from unnecessarily ping-ponging to lower legacy 3G / 2G systems. Furthermore, certain embodiments allow 5G-centric UEs to stay in 5G / 4G systems as long as possible with enhanced performance.

[0104] Certain embodiments also avoid complex recovery logic from legacy systems to 5G / 4G systems. In addition, certain embodiments can reduce power usage in 5G-centric UEs. In addition, certain embodiments can reduce interference in the network.

[0105] Other variations of the above embodiments are also possible. For example, the triggering of the fallback evaluation may be based on additional or different criteria, such as taking into account the location of nearby traditional base stations. In addition, some embodiments may implement a ping-pong condition check to ensure that the UE performs fallback at an appropriate frequency.

[0106] The above method can be applied to various different devices, taking user equipment as an example. More generally, the method can be used in a node of a wireless network. Fig.10 Nodes according to some embodiments are shown. Fig.11 A network including a plurality of nodes is shown in accordance with some embodiments.

[0107] like Fig.10 As shown, node 1000 may include a processor 1002, a memory 1004, and a transceiver 1006. These components are shown as being connected to each other via a bus 1008, but other types of connections are also allowed. Fig.11 When the user equipment 1102 in FIG. 100 is configured as a user device 1102, other components may also be included, such as a user interface (UI), a sensor, etc. Similarly, when the node 1000 is configured as Fig.11 When the core network element 1106 in the server system is used, the node 1000 can be implemented as a blade in a server system. Other implementations are also possible.

[0108] The transceiver 1006 may include any suitable device for transmitting and / or receiving data. For example, the transceiver 1006 may implement a protocol stack (also referred to as layer 2 circuitry) and a physical layer (also referred to as layer 1 circuitry), such as described in detail in the accompanying drawings. Figure 2 and Figure 6Although only one transceiver 1006 is shown for simplicity of illustration, node 1000 may include one or more transceivers. Antenna 1010 is shown as a possible communication mechanism for node 1000. Multiple antennas and / or antenna arrays may be utilized. In addition, examples of node 1000 may communicate using wired technology instead of wireless technology, or may communicate using wireless technology in addition to wired technology. For example, Fig.11 The access node 1104 may communicate wirelessly with the user equipment 1102 and may communicate via a wired connection (eg, via an optical or coaxial cable) with the core network element 1106. Other communication hardware such as a network interface card (NIC) may also be included.

[0109] like Fig.10 As shown, node 1000 may include processor 1002. Although only one processor is shown, it should be understood that multiple processors may be included. Processor 1002 may include a microprocessor, a microcontroller, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a programmable logic device (PLD), a state machine, a gate logic, a discrete hardware circuit, and other suitable hardware for performing the various functions described in this disclosure. Processor 1002 may be a hardware device with one or more processing cores. Processor 1002 may execute software. Whether referred to as software, firmware, middleware, microcode, hardware description language or other names, software should be broadly interpreted as instructions, instruction sets, codes, code segments, program codes, programs, subroutines, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, execution threads, processes, functions, etc. Software may include computer instructions written in an interpreted language, compiled languages, or machine codes. Other techniques for indicating hardware may also be classified under the broad category of software. Processor 1002 may be a baseband chip. Node 1000 may also include other processors not shown, such as a central processing unit of the device, a graphics processor, etc. Processor 1002 may include internal memory (also referred to as local memory, which may be used as a memory for L2 data) Fig.101000). The processor 1002 may include, for example, a radio frequency chip integrated in a baseband chip, or may be provided separately. The processor 1002 may be used as a modem of the node 1000, or may be an element or component of the modem. Other arrangements and configurations are also permitted.

[0110] like Fig.10 As shown, node 1000 may also include a memory 1004. Although only one memory is shown, it should be understood that multiple memories may be included. Memory 1004 may broadly include memory and storage. For example, memory 1004 may include random access memory (random-access memory, RAM), read-only memory (read-only memory, ROM), static RAM (static RAM, SRAM), dynamic RAM (dynamic RAM, DRAM), ferroelectric RAM (ferro-electric RAM, FRAM), electrically erasable programmable ROM (electrically erasable programmable ROM, EEPROM), CD-ROM, or other optical disk storage, hard disk drive (hard disk drive, HDD), such as disk storage or other magnetic storage devices, flash drives, solid-state drives (solid-state drive, SSD), or any other medium that can be used to carry or store the required program code in the form of instructions that can be accessed and executed by processor 1002. In general, memory 1004 can be implemented as any computer-readable medium, such as a non-temporary computer-readable medium. The memory 1004 may be shared by the processor 1002 and other components of the node 1000 , such as a graphics processor or a central processing unit (not shown).

[0111] like Fig.11 As shown, the wireless network 1100 may include a network of nodes, such as UE 1102, access node 1104, and core network element 1106. User equipment 1102 may be any terminal device, such as a mobile phone, a desktop computer, a laptop computer, a tablet computer, a vehicle-mounted computer, a game console, a printer, a positioning device, a wearable electronic device, a smart sensor, or any other device capable of receiving, processing, and sending information, such as a vehicle to everything (V2X) network, any member of a cluster network, a smart grid node, or an Internet of Things (IoT) node. It should be understood that user equipment 1102 is shown as a mobile phone only in an illustrative and non-limiting manner.

[0112] The access node 1104 may be a device that communicates with the user equipment 1102, such as a wireless access point, a base station (BS), a node B, an enhanced node B (eNodeB or eNB), a next-generation node B (gNodeB or gNB), a cluster master node, etc. The access node 1104 may be connected to the user equipment 1102 by wire, wirelessly connected to the user equipment 1102, or any combination thereof. The access node 1104 may be connected to the user equipment 1102 through multiple connections, and the user equipment 1102 may also be connected to other access nodes in addition to the access node 1104. The access node 1104 may also be connected to other UEs. It should be understood that the access node 1104 is shown as a radio tower in an illustrative and non-limiting manner.

[0113] The core network element 1106 can serve the access node 1104 and the user equipment 1102 to provide core network services. Examples of the core network element 1106 may include a home subscriber server (HSS), a mobility management entity (MME), a serving gateway (SGW), or a packet data network gateway (PGW). These are examples of core network elements of an evolved packet core (EPC) system, which is the core network of an LTE system. Other core network elements can be used in LTE and other communication systems. In some embodiments, the core network element 1106 includes an access and mobility management function (AMF) device, a session management function (SMF) device, or a user plane function (UPF) device of the core network of the NR system. It should be understood that the core network element 1106 is shown as a group of rack servers in an illustrative and non-limiting manner.

[0114] The core network element 1106 may be connected to a larger network such as the Internet 1108 or another IP network to transmit packet data over any distance. Thus, data from the user equipment 1102 may be transmitted, for example, using a wired connection or a wireless connection to other UEs connected to other access points (including, for example, a computer 1110 connected to the Internet 1108), or to a tablet 1112 wirelessly connected to the Internet 1108 via a router 1114. Thus, the computer 1110 and the tablet 1112 provide other examples of possible UEs, and the router 1114 provides another example of a possible access node.

[0115] A general example of a rack-mounted server is provided as an illustration of a core network element 1106. However, there may be multiple elements in the core network, including database servers, such as database 1116, and security and authentication servers, such as authentication server 1118. For example, database 1116 may manage data related to a user's subscription to a network service. A home location register (HLR) is an example of a standardized database of subscriber information for a cellular network. Similarly, authentication server 1118 may handle authentication of users, sessions, and the like. In an NR system, an authentication server function (AUSF) device may be a specific entity that performs user equipment authentication. In some embodiments, a single server rack may handle multiple such functions, such that the connections between core network element 1106, authentication server 1118, and database 1116 may be local connections within a single rack.

[0116] Fig.11 Each network element of the wireless network 1100 can be regarded as a node of the wireless network 1100. More details about possible implementations of the nodes are described above. Fig.10 The description of the node 1000 in FIG. 1 is provided by way of example. The node 1000 may be configured as Fig.11 1102, access node 1104, or core network element 1106 in the core network. Similarly, node 1000 may also be configured as Fig.11 The computer 1110, router 1114, tablet computer 1112, database 1116, or authentication server 1118.

[0117] In various aspects of the present disclosure, the functions described herein may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or encoded as instructions or code on a non-transitory computer-readable medium. Computer-readable media include computer storage media. Storage media may be a computer program product such as a computer program product. Fig.10Any available medium accessed by a computing device such as the node 1000 in. Such computer-readable media may include, for example, but not limited to, RAM, ROM, EEPROM, CD-ROM, or other optical disk storage, HDD, such as disk storage or other magnetic storage devices, flash drives, SSDs, or any other medium that can be used to carry or store the required program code in the form of instructions or data structures and can be accessed by a processing system (such as a mobile device or a computer). Disks and optical disks used herein include CDs, laser disks, optical disks, DVDs, and floppy disks, wherein disks typically reproduce data magnetically, while optical disks reproduce data optically by lasers. The above combination should also be included in the scope of computer-readable media.

[0118] According to one aspect, a method for fallback processing may include operating a user equipment with a fifth generation (5G) wireless access technology. The method may also include keeping second generation (2G) and third generation (3G) physical layer components in a hot state. The method may also include keeping 2G and 3G layer 2 components in an inactive state.

[0119] In some embodiments, the method may further include powering on at least one of the 2G and 3G layer 2 components when it is determined that a fallback should be performed.

[0120] In some embodiments, the method may further include reselecting from the 5G radio access technology to the fourth generation (4G) radio access technology. After reselecting to the 4G radio access technology, the 2G and 3G physical layer components may continue to be kept in a hot state, and the 2G and 3G layer 2 components may be kept in an inactive state.

[0121] In some embodiments, the user equipment may be configured to operate in at least one of a standalone mode or a non-standalone mode with 5G radio access technology.

[0122] In some embodiments, the method may further include maintaining a fourth generation (4G) physical layer component in a hot state. The method may further include maintaining a 4G layer 2 component in an inactive state.

[0123] According to another aspect, a method for fallback processing may include operating a user equipment with a fifth generation (5G) wireless access technology. The method may also include switching to a second generation (2G) or third generation (3G) wireless access technology only when out of service (OOS) coverage or an Internet Protocol (IP) multimedia subsystem (IMS) failure occurs.

[0124] In some embodiments, the method may further include detecting that the user equipment is experiencing OOS coverage of 5G. The above transition may be based on the detected OOS coverage.

[0125] In some embodiments, the method may further include detecting an IMS failure. The above transition may be based on the detected IMS failure.

[0126] In some embodiments, the user equipment may be configured to operate in at least one of a standalone mode or a non-standalone mode with 5G radio access technology.

[0127] According to another aspect, a method for fallback processing may include operating a user equipment with a fifth generation (5G) wireless access technology. The method may also include determining a likelihood of falling back to at least one of a second generation (2G) or a third generation (3G) wireless access technology. The method may also include falling back to a 2G or 3G wireless access technology only when the likelihood exceeds a threshold.

[0128] In some embodiments, this determination may include taking into account the locations of neighboring legacy base stations.

[0129] In some embodiments, the determination may include taking into account signal characteristics of signals received at the user equipment.

[0130] In some embodiments, the determination may include considering an average data buffer queue size at the user equipment.

[0131] In some embodiments, the determination may include considering a minimum delay value for packet data applications at the user equipment.

[0132] In some embodiments, this determination may be performed based on determining that the received power has been below a threshold power level for a predetermined period of time.

[0133] According to another aspect, a method for fallback processing may include operating a user equipment with a fifth generation (5G) radio access technology. The method may also include falling back to at least one of a second generation (2G), a third generation (3G), or a fourth generation (4G) radio access technology. The method may also include performing only an idle mode search for a 5G radio access technology system when attempting to return from a 2G, 3G, or 4G radio access technology to a 5G radio access technology.

[0134] According to another aspect, an apparatus for fallback processing may include at least one processor and at least one memory including computer program code. The at least one memory and computer program code may be used to, together with the at least one processor, cause the apparatus to operate at least a fifth generation (5G) wireless access technology. The at least one memory and computer program code may also be used to, together with the at least one processor, cause the apparatus to at least keep second generation (2G) and third generation (3G) physical layer components in a hot state. The at least one memory and computer program code may also be used to, together with the at least one processor, cause the apparatus to at least keep 2G and 3G layer 2 components in an inactive state.

[0135] According to another aspect, a device for fallback processing may include at least one processor and at least one memory including computer program code. The at least one memory and computer program code may be used to, together with the at least one processor, cause the device to operate at least with a fifth generation (5G) wireless access technology. The at least one memory and computer program code may also be used to, together with the at least one processor, cause the device to switch to a second generation (2G) or third generation (3G) wireless access technology at least only when out of service (OOS) coverage or an Internet Protocol (IP) multimedia subsystem (IMS) failure occurs.

[0136] According to another aspect, a device for fallback processing may include at least one processor and at least one memory including computer program code. The at least one memory and computer program code may be used to, together with the at least one processor, cause the device to operate at least with a fifth generation (5G) wireless access technology. The at least one memory and computer program code may also be used to, together with the at least one processor, cause the device to at least determine the possibility of falling back to at least one of a second generation (2G) or a third generation (3G) wireless access technology. The at least one memory and computer program code may also be used to, together with the at least one processor, cause the device to fall back to a 2G or 3G wireless access technology at least only when the possibility exceeds a threshold.

[0137] According to another aspect, a device for fallback processing may include at least one processor and at least one memory including computer program code. At least one memory and computer program code may be used to operate the device with at least one processor at least in a fifth generation (5G) wireless access technology. At least one memory and computer program code may also be used to cause the device to fall back to at least one of the second generation (2G), third generation (3G), or fourth generation (4G) wireless access technologies together with at least one processor. At least one memory and computer program code may also be used to cause the device to perform only an idle mode search for a 5G wireless access technology system when attempting to return from a 2G, 3G, or 4G wireless access technology to a 5G wireless access technology together with at least one processor.

[0138] The foregoing description of the specific embodiments will reveal the general nature of the present disclosure so that others can easily modify and / or adapt the various applications of such specific embodiments by applying knowledge within the technical scope of the art without departing from the general concept of the present disclosure, without excessive experimentation. Therefore, based on the teachings and guidance presented herein, such adaptations and modifications are intended to fall within the meaning and scope of the equivalents of the disclosed embodiments. It should be understood that the terms or terms herein are intended to describe rather than limit, so that the terms or terms of this specification will be interpreted by those skilled in the art according to teachings and guidance.

[0139] The embodiments of the present disclosure have been described above with the aid of functional building blocks that illustrate the implementation of specific functions and their relationships. For ease of description, the boundaries of these functional building blocks are arbitrarily defined herein. Alternative boundaries may be defined as long as the specified functions and their relationships are properly performed.

[0140] The Summary and Abstract sections may set forth one or more but not all exemplary embodiments of the present disclosure as contemplated by the inventor(s), and thus, are not intended to limit the present disclosure and the appended claims in any way.

[0141] Various functional blocks, modules, and steps are disclosed above. The specific arrangements provided are illustrative and not restrictive. Therefore, functional blocks, modules, and steps can be reordered or combined in a manner different from the examples provided above. Likewise, some embodiments include only a subset of functional blocks, modules, and steps and allow any such subset.

[0142] The breadth and scope of the present disclosure should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.

Claims

1. A method for fallback processing, comprising: Operate user equipment with fifth generation (5G) radio access technology; Keeping second generation (2G) and third generation (3G) physical layer components hot; as well as Keep 2G and 3G Layer 2 components inactive; When it is determined that a fallback should be performed, at least one of the 2G and 3G layer 2 components is powered on.

2. The method according to claim 1, further comprising: Reselecting from the 5G wireless access technology to a fourth generation (4G) wireless access technology, wherein after reselecting to the 4G wireless access technology, continuing to maintain the 2G and 3G physical layer components in the hot state, and maintaining the 2G and 3G layer 2 components in the inactive state.

3. The method according to claim 1, wherein: The user equipment is configured to operate in at least one independent mode or non-independent mode with the 5G radio access technology.

4. The method according to claim 1, further comprising: Keeping fourth generation (4G) physical layer components hot; as well as Keep 4G Layer 2 components inactive.

5. A device for fallback processing, comprising: at least one processor; as well as at least one memory including computer program code, wherein the at least one memory and the computer program code are used to, together with the at least one processor, enable the apparatus to at least operating the device with fifth generation (5G) wireless access technology; Keeping second generation (2G) and third generation (3G) physical layer components hot; and Keep 2G and 3G Layer 2 components inactive; When it is determined that a fallback should be performed, at least one of the 2G and 3G layer 2 components is powered on.

Images