Reduced Power Roaming for Accessory Devices

Abstract

The present disclosure relates to reduced power roaming for accessory devices. The present invention discloses a user equipment (UE) configured to prioritize multiple public land mobile networks (PLMNs) from an aggregated roaming priority public land mobile network (RPPLMN) list into multiple prioritized PLMNs, the RPPLMN list containing the multiple PLMNs; and connect to a selected PLMN from the multiple prioritized PLMNs based on the priority of the selected PLMN. The UE is further configured to determine whether an application processor (AP) assisted location service is available, wherein the AP assisted service is configured to identify multiple deployed PLMNs at a current geographic location of the UE and multiple frequencies used by the multiple deployed PLMNs; and when the AP assisted location service is available, determine whether a registered PLMN (RPLMN) is valid in a current mobile country code (MCC).

Description

Technical Field

[0001] The present disclosure relates to wireless communications and, more particularly, to reduced power roaming of accessory devices. Background Art

[0002] A user equipment (UE) may be paired with another UE (e.g., a smartwatch) via a short-range communication protocol. For example, the UE may be a companion device and the additional UE may be an accessory device. The companion device and the accessory device may communicate via a short-range communication protocol to perform various operations. In some cases, the additional or accessory UE may be capable of cellular communications over a wireless network without the companion UE.

[0003] Typically, accessory devices have limited battery capacity. Therefore, it is important that their power is used efficiently and not wasted unnecessarily. For example, autonomous cellular communications of an accessory device (without the help of a companion device) consume a large amount of power. Roaming is an exacerbating factor when it comes to power consumption for a variety of reasons. For example, if an accessory device is roaming and is not paired with a companion device, the accessory device will need to scan multiple frequencies / bands to find a roaming partner network to which it can connect. Roaming agreements between cellular providers are often unknown to the accessory device, which creates challenges when attempting to register on a roaming partner network (e.g., risk of being rejected on multiple roaming networks).

[0004] Furthermore, even if there is a roaming agreement with a provider, with respect to the network guide of roaming (SoR), it is possible that an accessory device that successfully registers on a roaming partner network may be denied a later registration with that same network. This may happen, for example, if the target cell is already overloaded with connected UEs. This results in additional registration attempts for the accessory device, resulting in more power consumption.

[0005] Furthermore, due to slower wireless connections and / or lower RATs (e.g., 2G / 3G), radio resource control (RRC) connections tend to be about 40% longer when roaming. Additionally, long round trip times (RTTs) are experienced because data traffic may be routed to the home network. Further, the lack of WiFi availability forces roaming UEs (or accessory devices) to utilize cellular communications more frequently, again resulting in increased power consumption.

[0006] Furthermore, due to rejection by the roaming partner network, the roaming UE (or accessory device) typically remains in limited service mode for a longer period of time, which results in a resume scan of frequencies that the UE can connect to, further resulting in additional power consumption. Finally, when there are multiple available roaming partner networks, the roaming UE (or accessory device) may remain connected to a low priority network and will perform periodic scans (e.g., every 6 minutes) for higher priority networks to which it can connect, resulting in additional power consumption.

[0007] For these reasons, a UE (eg, an accessory device) may drain its battery significantly faster than when it is connected to its home network. Summary of the invention

[0008] Some example embodiments are directed to a processor of a user equipment (UE) configured to perform operations including: prioritizing a plurality of public land mobile networks (PLMNs) from an aggregated roaming priority public land mobile network (RPPLMN) list into a plurality of prioritized PLMNs, the RPPLMN list comprising the plurality of PLMNs; and connecting to a selected PLMN from the plurality of prioritized PLMNs based on a priority of the selected PLMN.

[0009] Other exemplary embodiments are directed to a user equipment (UE) having: a transceiver configured to communicate with a plurality of networks; and a processor communicatively coupled to the transceiver and configured to perform operations. The operations include: prioritizing a plurality of public land mobile networks (PLMNs) from an aggregated roaming priority public land mobile network (RPPLMN) list into a plurality of prioritized PLMNs, the RPPLMN list comprising the plurality of PLMNs; and connecting to a selected PLMN from the plurality of prioritized PLMNs based on a priority of the selected PLMN. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 Exemplary network arrangements are shown according to various exemplary embodiments.

[0011] Figure 2 An exemplary UE according to various exemplary embodiments is shown.

[0012] Figure 3 Methods of performing cell selection by a UE according to various exemplary embodiments are shown.

[0013] Figure 4 A diagram illustrating a reduced power recovery scan performed by a UE according to various exemplary embodiments is shown. DETAILED DESCRIPTION

[0014] The exemplary embodiments may be further understood by reference to the following description and associated drawings, wherein similar elements have the same reference numerals. The exemplary embodiments describe devices, systems, and methods for reducing power consumption of accessory devices while roaming.

[0015] The exemplary embodiments are described with respect to UE. However, the use of UE is for illustration purposes only. The exemplary embodiments can be utilized with any electronic component that can establish a connection with a network and is configured with hardware, software and / or firmware for exchanging information and data with the network. Therefore, the UE described herein is used to represent any electronic component.

[0016] The exemplary embodiments are also described with reference to a specific type of UE (hereinafter referred to as an "accessory device" or "accessory UE"). An accessory device is typically a UE that has less capabilities or limited capabilities (e.g., limited battery power) relative to some aspects of the UE. Some examples of accessory UEs may include smart watches, IoT devices, etc. As described above, in some cases, these accessory devices may be able to access a cellular network via another device referred to herein as a "matching device." However, it should be understood that the accessory devices described herein do not require the ability to connect to a cellular network via a matching device, for example, the accessory device may have a cellular chip and may not have a short-range communication chip such as a Bluetooth chip. In addition, it should be understood that even though the exemplary embodiments are described with reference to an accessory UE, the exemplary embodiments may be implemented in any type of UE.

[0017] The exemplary embodiments are also described with reference to home networks and roaming networks including 5G New Radio (NR) radio access technology (RAT) and Long Term Evolution (LTE) RAT. However, the exemplary embodiments are applicable to UEs connected to or attempting to connect to any type of cellular RAT (including legacy RATs such as 3G, 2G, GSM, etc.).

[0018] As mentioned above, there are many factors that can quickly drain the battery power of an accessory device when roaming. Multiple registration attempts, scanning all available frequencies, and constantly scanning for higher priority roaming partner networks are just some of the issues that lead to unnecessary power consumption. Typically, the accessory device includes a list of operator-controlled public land mobile networks (OPLMNs) stored on the device's Subscriber Identity Module (SIM) card that the device can reference when searching for roaming partners. However, this list is not an updated list and leaves the UE searching / scanning for roaming partner networks on which the UE can register.

[0019] According to an exemplary embodiment, an aggregated roaming priority public land mobile network (PLMN) list can be compiled, stored, and dynamically updated on the accessory device. The aggregated list is based on a number of different sources. The accessory device utilizes the list to ensure that a desired available network can be selected without wasting registration attempts on less desirable networks (as defined by the list).

[0020] Another problem that causes unnecessary power consumption is the number of frequencies scanned by the accessory device. There are usually multiple frequency bands, each of which has hundreds of frequencies. Typically, the UE and / or accessory device must scan every frequency of each frequency band to find a suitable roaming PLMN.

[0021] According to an exemplary embodiment, the accessory device can utilize its application processor (AP) to identify a list of all deployed PLMNs at the geographic location of the accessory device and the frequencies used by each of the deployed PLMNs. Thus, the number of frequencies scanned by the accessory device is significantly reduced, thereby advantageously saving power. AP-assisted roaming can be used at any time (e.g., at power-up, during limited service or no service periods, etc.).

[0022] Figure 1 An exemplary network arrangement 100 according to various exemplary embodiments is shown. The network arrangement 100 includes UEs 110, 112. Those skilled in the art will appreciate that UEs 110, 112 may be any type of electronic component configured to communicate via a network, such as a mobile phone, a tablet, a smart phone, a phablet, an embedded device, a wearable device, a Cat-M device, a Cat-M1 device, an MTC device, an eMTC device, other types of Internet of Things (IoT) devices, etc. A practical network arrangement may include any number of UEs used by any number of users. Therefore, an example with two UEs 110, 112 is provided for illustrative purposes only.

[0023] Each of the UEs 110, 112 may be configured to communicate directly with one or more networks. In the example of the network configuration 100, the networks with which the UEs 110, 112 may wirelessly communicate are a 5G New Radio (NR) radio access network (5G NR-RAN) 120, an LTE radio access network (LTE-RAN) 122, and a wireless local area network (WLAN) 124. However, it should be understood that the UEs 110, 112 may also communicate with other types of networks, and that the UEs 110, 112 may also communicate with the networks via a wired connection. Thus, UE 110, 112 may include a 5G NR chipset for communicating with 5G NR-RAN 120, an LTE chipset for communicating with LTE-RAN 122, a Universal Mobile Telecommunications System (UMTS) chipset for communicating with a first legacy network (e.g., a 3G network) (not shown), a Global System for Mobile Communications (GSM) chipset for communicating with a second legacy network (e.g., a 2G network) (not shown), and an ISM chipset for communicating with WLAN 124.

[0024] UE 110, 112 can communicate with each other without using networks 120-124. For example, UE 110, 112 can communicate with each other using short-range communication protocols such as Bluetooth, short-range WiFi, etc. Therefore, if UE 110 and UE 112 are close to each other (e.g., within a distance where Bluetooth communication can be performed), UE 110 and UE 112 can exchange data. In an exemplary scenario, if a short-range communication protocol is used, UE 110 and UE 112 may have a matching relationship, where UE 110 is a matching device (e.g., a mobile phone, a tablet computer, a smart phone, a tablet phone) and UE 112 is an accessory device (e.g., a wearable device, such as a smart watch). Therefore, in certain operating modes, UE 112 can be configured to access network services using only a short-range communication protocol without connecting to any of networks 120-124. In this exemplary operating mode, companion UE 110 may connect to one or more of networks 120-124 and relay data exchanged with the one or more networks 120-124 via a short-range communication path to accessory UE 112. However, in other operating modes, such as when the Bluetooth connection is severed due to UE 112 moving out of proximity of UE 110 or disabling the Bluetooth functionality of UE 112, UE 112 may independently connect to one or more of networks 120 to 124.

[0025] 5G NR-RAN 120 and LTE-RAN 122 may be parts of cellular networks that may be deployed by cellular providers (e.g., Verizon, AT&T, T-Mobile, etc.). These networks 120, 122 may include, for example, cells or base stations (NodeB, eNodeB, HeNB, eNBS, gNB, gNodeB, macrocell base stations, microcell base stations, small cell base stations, femtocell base stations, etc.) configured to send and receive traffic from UEs equipped with appropriate cellular chipsets. WLAN 124 may include any type of wireless local area network (WiFi, hotspot, IEEE 802.11x network, etc.).

[0026] UE 110, 112 may be connected to 5G NR-RAN 120 via gNB 120A and / or to LTE RAN 122 via eNB 122A. gNB 120A may be configured with the necessary hardware (e.g., antenna array), software and / or firmware to perform massive multiple-input multiple-output (MIMO) functionality. Massive MIMO may refer to a base station configured to generate multiple beams for multiple UEs. During operation, UE 110, 112 may be within range of multiple gNBs. Therefore, simultaneously or alternatively, UE 110, 112 may also be connected to 5G NR-RAN 120 via gNB 120B. Reference to two gNBs 120A, 120B is for illustrative purposes only. The exemplary embodiments may apply to any appropriate number of gNBs. In addition, the UEs 110, 112 may communicate with the eNB 122A of the LTE-RAN 122 to transmit and receive control information for downlink and / or uplink synchronization with respect to the 5G NR-RAN 120 connection.

[0027] Those skilled in the art will appreciate that any relevant procedures may be performed to connect the UE 110, 112 to the 5G LTE-RAN 120 and / or the LTE-RAN 122. For example, as discussed above, the 5G NR-RAN 120 and the LTE-RAN 122 may be associated with a particular cellular provider at which the UE 110, 112 and / or its user has a contract and credential information (e.g., stored on a SIM card). Upon detecting the presence of the 5G NR-RAN 120 and / or the LTE RAN 122, the UE 110, 112 may transmit the corresponding credential information in order to associate with the 5G NR-RAN 120 and / or the LTE RAN 122. More specifically, the UE 110, 112 may be associated with a particular base station (e.g., a gNB 120A of the 5G NR-RAN 120, or an eNB 122A of the LTE-RAN 122).

[0028] In addition to networks 120, 122, and 124, network arrangement 100 also includes a cellular core network 130, the Internet 140, an IP multimedia subsystem (IMS) 150, and a network service backbone 160. Cellular core network 130 (e.g., 5GC of a 5G NR network) can be viewed as an interconnected collection of components that manage the operation and traffic of a cellular network. Cellular core network 130 also manages traffic flowing between a cellular network and the Internet 140.

[0029] The IMS 150 may be generally described as an architecture for delivering multimedia services to the UE 110 using the IP protocol. The IMS 150 may communicate with the cellular core network 130 and the Internet 140 to provide multimedia services to the UE 110. The network service backbone 160 communicates directly or indirectly with the Internet 140 and the cellular core network 130. The network service backbone 160 may be generally described as a set of components (e.g., servers, network storage arrangements, etc.) that implement a set of services that may be used to extend the functionality of the UE 110 to communicate with various networks.

[0030] Figure 2 An exemplary UE 110 or 112 is shown according to various exemplary embodiments. The following will be described from the perspective of UE 112 (e.g., an accessory device). However, it should be noted that the following description of UE 112 may also apply to UE 110. Figure 1 100 is used to describe the UE 112. The UE 112 may represent any electronic device and may include a processor 205, a memory arrangement 210, a display device 215, an input / output (I / O) device 220, a transceiver 225, and other components 230. The other components 230 may include, for example, an audio input device, an audio output device, a battery to provide a limited power source, a data acquisition device, a port for electrically connecting the UE 112 to other electronic devices, one or more antenna panels, etc.

[0031] Processor 205 may be configured to execute multiple engines of UE 112. For example, the engines may include a roaming management engine 235. Roaming management engine 235 may perform various operations related to roaming, such as compiling and updating an aggregated roaming priority PLMN (RPPLMN) list and searching for PLMN frequencies that UE 112 may register with while roaming.

[0032] The above-mentioned engine is merely exemplary as an application (e.g., a program) executed by the processor 205. The functions associated with the engine may also be represented as an independent combined component of the UE 112, or may be a modular component coupled to the UE 112, for example, an integrated circuit with or without firmware. For example, the integrated circuit may include an input circuit for receiving a signal and a processing circuit for processing the signal and other information. The engine may also be embodied as an application or multiple separate applications. In addition, in some UEs, the functionality described for the processor 205 is shared between two or more processors such as a baseband (BB) processor and an application processor (AP). The exemplary embodiments may be implemented in any of these or other configurations of the UE.

[0033] The memory arrangement 210 may be a hardware component configured to store data related to operations performed by the UE 112. The display device 215 may be a hardware component configured to display data to a user, and the I / O device 220 may be a hardware component that enables user input. The display device 215 and the I / O device 220 may be separate components or may be integrated together (such as a touch screen). The transceiver 225 may be a hardware component configured to establish a connection with the 5G NR-RAN 120, LTE-RAN 122, WLAN 124, etc. Thus, the transceiver 225 may operate on multiple different frequencies or channels (e.g., a continuous set of frequencies).

[0034] Figure 3 A method 300 of performing cell selection by a UE 112 according to various exemplary embodiments is shown. At 302, the UE 112 is powered on. It should be noted that powering on does not mean that the UE 112 is completely powered off, but may also cover scenarios where the transceiver 225 of the UE 112 that was previously disabled is now enabled (e.g., leaving airplane mode, leaving companion mode, etc.).

[0035] At 304, UE 112 locally derives the registered PLMNs (RPLMNs) from the memory arrangement 210 of UE 112 or via peer-to-peer (P2P) communication (e.g., via Bluetooth) from the companion UE 110. In addition, UE 112 composes an aggregated roaming priority PLMN (RPPLMN) list based on the plurality of source priority lists. In some embodiments, the aggregated RPPLMNs include: (1) RPLMNs derived locally and / or from UE 110, (2) an authorized PLMN list including a global roaming partner list that has a roaming agreement with the cellular provider of UE 112, (3) an operator-controlled public land mobile network (OPLMN) list stored on a universal SIM card of UE 112 (or on a SIM card of the companion UE 110 if the OPLMN list on the SIM of UE 112 is empty), and / or (4) a user-based PLMN list.

[0036] The RPLMN is the PLMN previously used by the UE 112 (or UE 110) when roaming at the current geographic location. As described above, the RPLMN may be stored locally on the UE 112 or UE 110 and shared with the UE 112 via short-range communication (e.g., Bluetooth). The RPLMN list includes PLMNs to which the UE 112 has previously been globally connected. Since the UE 112 is an accessory device, it is more likely that the UE 110 will have the most recent RPLMN since users typically roam more frequently with their companion devices. However, this is not always the case as it all depends on user preference. If the companion UE 110 has gone through the roaming network selection process and has selected a PLMN, the companion UE 110 may share this information with the UE 112 so that the UE 112 may register on the same PLMN, thereby saving power. In some embodiments, if companion UE 110 receives a rejection from one or more networks during the roaming network selection process, companion UE 110 can share this information with UE 112 so that UE 112 does not waste power trying to register on these PLMNs. The priority between the RPLMNs stored on accessory device 112 and the RPLMNs stored on companion device 110 and shared with the accessory device can be based on the timestamps associated with the respective RPLMNs. The use of various priorities will be described in more detail below.

[0037] The authorized PLMN list represents roaming partners with which the cellular provider of UE 112 has roaming agreements. The authorized PLMN list may be periodically updated by pushing the updated list to UE 112 when UE 112 is connected to a WiFi network. For example, the manufacturer of UE 112 may maintain the authorized PLMNs on one or more servers within its network through its association with various operators. The authorized PLMNs may be stored, for example, on a server that is part of the network service backbone 160. The authorized PLMNs may then be periodically pushed to UE 112 when the UE is connected to WLAN 124 (e.g., any WiFi network).

[0038] The OPLMN list is a list of PLMNs configured by the UE's cellular provider on the SIM of UE 112 and / or the SIM of UE 110. In some embodiments, the SIM of UE 110 may be configured with more PLMNs because it is generally considered to be the primary device to be used during roaming. In this case, UE 110 may share the OPLMNs configured on its SIM with UE 112.

[0039] The user-based PLMN list may be derived from other UEs with the same cellular provider (e.g., crowdsourcing). The user-based PLMN list includes PLMNs to which other UEs with various cellular providers are globally connected. UE 112 may use its cellular provider and current geographic location to narrow down the user-based PLMN list.

[0040] In some embodiments, UE 112 assigns priorities to the multiple PLMN lists discussed above. In some embodiments, UE 112 gives a first priority to the latest RPLMN (local or P2P) from the aggregated RPPLMN list, a second priority to PLMNS on the authorized PLMN list, a third priority to PLMNS on the OPLMN list, and a fourth priority to PLMNS on the user-based PLMN list.

[0041] The aggregated RPPLMN list is stored on the UE 112 and is filtered using the detected Mobile Country Code (MCC) of the country in which the UE 112 is located. In some embodiments, if the UE 112 is near the border of the country, the UE 112 may also include PLMNs from neighboring countries when filtering the list. The UE 112 may utilize the aggregated PLMN list when deciding which PLMNs to scan first, thereby saving power by potentially avoiding scanning lower priority PLMNs entirely. The aggregated RPPLMN further allows the UE 112 to select the highest priority PLMN if multiple PLMNs are available at a given time and location. In some embodiments, unknown PLMNs that are not on the aggregated RPPLMN list may be treated as prohibited PLMNs by the UE 112.

[0042] return Figure 3 Once the aggregated RPPLMN has been formed, at 306, the UE 112 determines whether AP assisted location is available. AP assisted location refers to the identification of one or more PLMNs deployed at the current location of the UE 112 and the frequencies used by those PLMNs by the AP of the UE 112 (e.g., the processor 205). The AP uses the geographic location of the UE 112 to provide this information to the UE. The location of the UE 112 can be determined based on any known location service (e.g., GPS location service, WiFi location service, etc.). It should be understood that although the exemplary embodiment describes that the AP is responsible for determining and storing location-related information, other components of the UE 112 can also perform the functions described herein for the AP.

[0043] If, at 306, AP assisted location is available because the location of UE 112 was successfully determined, then at 308, UE 112 determines whether an RPLMN is valid for the currently detected MCC. If one or more RPLMNs are valid in the current MCC, then at 310, the RPLMN is selected. At 312, UE 112 scans the frequencies used by the AP identified as RPLMNs. At 314, UE 112 performs cell selection for the selected RPLMN using the frequencies from 312.

[0044] However, if at 308, UE 112 determines that no RPLMN is valid in the current MCC, then at 316, UE 112 utilizes the aggregated RPPLMN list. In this case, at 312, UE 112 scans the frequencies identified by the AP for PLMNs deployed at the current location of UE 112. UE 112 prioritizes the frequency scan according to the aggregated RPPLMN priority discussed above (e.g., scans authorized PLMN frequencies first, then scans OPLMN frequencies second, etc.). At 314, UE 112 performs cell selection for the selected PLMN using the frequencies from 312.

[0045] If, at 306, AP assisted location is not available because the location of UE 112 cannot be determined, then at 318, UE 112 determines whether the timestamp of the RPLMN is within a predetermined time period. For example, if UE 112 has been connected to a PLMN (thus making it an RPLMN) and subsequently powered off and on, the RPLMN timestamp is relatively recent. If the RPLMN timestamp is within a predetermined time period, then at 210, the RPLMN is selected. Once the RPLMN is identified, the AP of UE 112 can provide the UE with the frequency utilized by the PLMN. At 322, UE 112 uses the frequency provided by the AP to connect to the RPLMN. However, if the connection fails (e.g., the registration attempt of UE 112 on the PLMN is rejected), UE 112 can perform a band scan limited to the RPLMN to determine the correct frequency. At 314, UE 112 performs cell selection for the selected PLMN using the frequency from 322.

[0046] However, if it is determined at 318 that the RPLMN timestamp is not within a predetermined time period (or if this is the first time that the UE 112 is at the current location), then at 324, the UE 112 determines whether there are one or more OPLMNs on the SIM card that the UE 112 can register with (whether the OPLMN is valid in the current location). If one or more OPLMNs are identified, then at 320, the UE 112 selects a PLMN based on the PLMN priorities defined above. Once a PLMN is selected, the method 300 proceeds to 322 and 314, as described above. If no OPLMN is identified on the SIM card, the UE 112 selects its home PLMN (HPLMN) at 326. However, because the UE 112 is not at home and is roaming, it will detect an MCC change. Therefore, the UE 112 will detect the available PLMNs at the location and will select a PLMN based on the PLMN priorities defined above. Once a PLMN is selected, the method 300 proceeds to 322 and 314, as described above.

[0047] Figure 4 A diagram illustrating a reduced power recovery scan performed by UE 112 according to various exemplary embodiments is shown. Figure 3 The operations described are relevant to the case where UE 112 is initially powered on (e.g., transceiver 225 is starting up). However, there may also be cases where UE 112 has been connected to a roaming network but subsequently goes out of service (OOS) or enters a limited service scenario. Typically, if this occurs, the UE will perform periodic scans (e.g., once every 5-10 seconds) to determine whether a previously used frequency is available or a cell is available, as shown at 410. However, these scans are performed blindly. As Figure 4 As shown, according to various exemplary embodiments, UE 112 may perform a stored list scan (SLS) of PLMNs and frequencies identified by the AP. The AP identifies these PLMNs and frequencies based on the current or last known location of UE 112 (the location where UE 112 moved out of service). UE 112 sorts the PLMNs / frequencies identified by the AP based on the PLMN priorities discussed above, as shown at 402, 404, 406, and 408. The UE then performs an SLS scan 414 of the prioritized frequencies. In some embodiments, as indicated at 416, UE 112 may repeat the scan of frequencies at the top of the PLMN priority list and / or frequencies that UE 112 previously camped on before moving out of service, because the likelihood that UE 112 will successfully register on those PLMNs is higher.

[0048] Aggregating RPPLMNs can reduce the number of scans that UE 112 performs when roaming, thereby improving the battery life of UE 112. For example, when a UE is rejected by a roaming network and there are multiple available networks, the UE will typically attempt to register on the network 5 times (e.g., every 10-15 seconds) according to the 3GPP standard. Each attempt will consume power. According to an exemplary embodiment, UE 112 can modify the retry counter so that UE 112 will increase the number of registration retries on higher priority PLMNs and eliminate retries on low priority PLMNs instead of continuously trying to connect to the roaming partner network. In some embodiments, UE 112 can additionally modify the time period between retries based on signal strength (e.g., a smaller period for strong signals and a larger period for weak signals). If during a registration attempt, UE 112 receives a rejection #15 "No suitable cell in the tracking area", UE 112 can immediately switch to an alternative RAT (e.g., 3G, 2G) in the same PLMN because the UE will be less likely to find an LTE network. However, if UE 112 is also rejected on the alternative RAT, UE 112 may add the PLMN to the forbidden PLMN list.

[0049] In some embodiments, in order to further save power, UE 112 may avoid continuous or concurrent registration attempts on multiple networks. On the contrary, in some embodiments, UE 112 may add random backoff so that it does not consume a lot of power in a short period of time. UE 112 may enter sleep mode during the random backoff period and then try to connect to the next PLMN. Such backoff timer is beneficial because it gives UE time to move away from the area where the roaming signal is weak, and the reconnection attempt will be useless and waste energy. In some embodiments, when a non-serious rejection is received or in an abnormal situation (e.g., continuous RACH failure), UE 112 may alternatively interleave registration attempts on the network. For example, if UE 112 receives a rejection #17 network failure after attempting to register on the highest priority PLMN, UE 112 may immediately try to register on the next PLMN. If the registration on the second PLMN fails, UE 112 may retry the registration on the first PLMN.

[0050] As described above, currently, a UE camping on a lower priority network will perform periodic scanning for a higher priority network. However, accessory devices such as UE 112 are generally not data-intensive devices and / or are not intended to display roaming operator names. Therefore, PLMN priority is less important. Therefore, according to some embodiments, as long as the functions of UE 112 are supported, regardless of the priority of the PLMN, UE 112 can remain camped on the current PLMN. Additionally or alternatively, if a cellular provider has only one roaming partner at a given location or has no preference for which roaming partner to use, periodic scanning can be completely eliminated. In some embodiments, the home PLMN (HPLMN) search can be limited to the area at the national border and eliminated in the non-border area relative to the country adjacent to the UE's home country.

[0051] In addition to the power saving features discussed above, in some embodiments, the UE 112 may also disable its UMTS and / or GSM chipsets if those RATs are not supported for the UE 112. Once the current MCC is detected, the UE 112 detects this situation and disables any unsupported chipsets to save power.

[0052] Although this patent application describes various combinations of various embodiments each having different features, those skilled in the art will understand that any feature of an embodiment may be combined with features of other embodiments in any manner not publicly denied or with features that are not functionally or logically inconsistent with the operation or function of the device of the embodiments disclosed in the present invention.

[0053] It is understood that the use of personally identifiable information should be subject to privacy policies and practices that are generally recognized to meet or exceed industry or government requirements for maintaining user privacy. Specifically, personally identifiable information data should be managed and processed to minimize the risk of unintentional or unauthorized access or use, and the nature of the authorized use should be clearly stated to users.

[0054] Those skilled in the art will appreciate that the exemplary embodiments described above may be implemented with any suitable software configuration or hardware configuration or combination thereof. Exemplary hardware platforms for implementing the exemplary embodiments may include, for example, Intel x86-based platforms with compatible operating systems, Windows OS, Mac platforms and MAC OS, mobile devices with operating systems such as iOS, Android, etc. In other examples, the exemplary embodiments of the above methods may be embodied as a program including lines of code stored on a non-transitory computer-readable storage medium, which, when compiled, may be executed on a processor or microprocessor.

[0055] It will be apparent to those skilled in the art that various modifications may be made to the present disclosure without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure is intended to cover modifications and variations of the present disclosure, provided that these modifications and variations are within the scope of the appended claims and their equivalents.

[0056] Priority / Incorporated by Reference

[0057] This patent application claims priority to U.S. Provisional Patent Application Serial No. 63 / 040907, filed on June 18, 2020, and entitled “Reduced Power Roaming by an Accessory Device,” which is incorporated herein by reference in its entirety.

Claims

1. An electronic device for user equipment UE, comprising a processor, wherein the processor is configured to perform operations, the operations comprising: Prioritizing a plurality of public land mobile networks PLMNs from an aggregated roaming priority public land mobile network RPPLMN list into a plurality of prioritized PLMNs, wherein the RPPLMN list is constructed based on a plurality of source priority lists and includes at least registered public land mobile networks RPLMNs; Selecting a PLMN from the plurality of prioritized PLMNs, the selecting being based at least on a priority of the selected PLMN, wherein the selecting further comprises: determining whether an application processor AP assisted location service is available, wherein the AP assisted location service is configured to identify a plurality of deployed PLMNs at a current geographic location of the UE and a plurality of frequencies used by the plurality of deployed PLMNs, When the AP assisted location service is available, determining whether the RPLMN is valid in the current mobile country code MCC, and When the AP assisted location service is unavailable, determining whether the timestamp of the RPLMN is within a predetermined time period; and Connecting to a selected PLMN among the plurality of prioritized PLMNs.

2. The electronic device of claim 1, wherein if the RPLMN is not valid in the current MCC, the selected PLMN is a PLMN among the plurality of deployed PLMNs having a higher priority than any other PLMN among the plurality of deployed PLMNs.

3. The electronic device of claim 1, wherein if the RPLMN is valid in the current MCC, the selected PLMN is the RPLMN.

4. The electronic device of claim 1, wherein if the timestamp of the RPLMN is within the predetermined time period, the selected PLMN is the RPLMN.

5. The electronic device of claim 1 , wherein the RPPLMN list further comprises one or more operator-controlled public land mobile networks (OPLMNs) stored on a subscriber identity module (SIM) card of the UE, and if the timestamp of the RPLMN is not within the predetermined time period, the operation further comprises: Determining whether the one or more OPLMNs are valid in the current geographic location of the UE.

6. The electronic device of claim 5, wherein if the one or more OPLMNs are valid in the current geographic location of the UE, the selected PLMN is an OPLMN of the one or more OPLMNs on the SIM card that has a higher priority than any other OPLMN.

7. The electronic device of claim 5, wherein if the one or more OPLMNs are not valid in the current geographic location of the UE, the operations further comprise: Attempt to connect to the Home Public Land Mobile Network (HPLMN); detecting all available PLMNs at the current geographical location of the UE, The selected PLMN is a PLMN among the available PLMNs that has a higher priority than any other available PLMNs.

8. The electronic device of claim 1, wherein if a failure occurs while connecting to the selected PLMN, waiting for a backoff period before attempting to connect to the selected PLMN or a second selected PLMN in the plurality of prioritized PLMNs.

9. The electronic device of claim 1, wherein the aggregated RPPLMN list is one of: (i) received from a source external to the UE, or (ii) constructed by the UE by retrieving information from multiple sources.

10. A user equipment UE, comprising: a transceiver configured to communicate with a plurality of networks; and a processor communicatively coupled to the transceiver and configured to perform operations including: Prioritizing a plurality of public land mobile networks PLMNs from an aggregated roaming priority public land mobile network RPPLMN list into a plurality of prioritized PLMNs, wherein the RPPLMN list is constructed based on a plurality of source priority lists and includes at least a registered public land mobile network RPLMN; Selecting a PLMN from the plurality of prioritized PLMNs, the selecting being based at least on a priority of the selected PLMN, wherein the selecting further comprises: determining whether an application processor AP assisted location service is available, wherein the AP assisted location service is configured to identify a plurality of deployed PLMNs at a current geographic location of the UE and a plurality of frequencies used by the plurality of deployed PLMNs, When the AP assisted location service is available, determining whether the RPLMN is valid in the current mobile country code MCC, and When the AP assisted location service is unavailable, determining whether the timestamp of the RPLMN is within a predetermined time period; as well as Connecting to a selected PLMN among the plurality of prioritized PLMNs.

11. The UE of claim 10, wherein if the RPLMN is not valid in the current MCC, the selected PLMN is a PLMN among the plurality of deployed PLMNs having a higher priority than any other PLMN among the plurality of deployed PLMNs.

12. The UE according to claim 10, wherein if the RPLMN is valid in the current MCC, the selected PLMN is the RPLMN.

13. The UE of claim 10, wherein if the timestamp of the RPLMN is within the predetermined time period, the selected PLMN is the RPLMN.

14. The UE of claim 10, wherein the RPPLMN list further comprises one or more operator-controlled public land mobile networks (OPLMNs) stored on a subscriber identity module (SIM) card of the UE, and if the timestamp of the RPLMN is not within the predetermined time period, the operation further comprises: determining whether the one or more OPLMNs are valid in the current geographic location of the UE, wherein if the one or more OPLMNs are valid in the current geographic location of the UE, the selected PLMN is an OPLMN of the one or more OPLMNs on the SIM card that has a higher priority than any other OPLMN.

15. The UE of claim 14, wherein if the one or more OPLMNs are not valid in the current geographic location of the UE, the operations further comprise: Attempt to connect to the Home Public Land Mobile Network (HPLMN); as well as detecting all available PLMNs at the current geographical location of the UE, The selected PLMN is a PLMN among the available PLMNs that has a higher priority than any other available PLMNs.

16. The UE of claim 10, wherein the UE is an accessory device having a companion relationship with a companion UE.

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