Patent Description:
UEs, such as smartphones, smartwatches, and tablets, are commonly able to connect to one or more wireless networks, such as those implemented by employing Third Generation Partnership Project (3GPP), Fourth Generation (<NUM>), Long Term Evolution (LTE), and Fifth Generation (<NUM>) New Radio (NR) radio access technologies (RATs), via connections with one or more associated BSs. A UE can obtain both data services and voice services via its connection to such wireless networks. When a UE that is connected to a wireless network exits the service area of the BSs that provide access to the wireless network, the UE enters an OOS state. Conventionally, when in the OOS state, the UE repeatedly scans one or more frequencies to find a valid wireless signal that will allow the UE to reestablish its connection to the wireless network - a process sometimes referred to as "scanning for service. " The UE typically continues to scan for service until a valid wireless signal is found, at which time the UE reestablishes its connection to the wireless network via the valid wireless signal - a process sometimes referred to as "acquiring service. " In some embodiments, the UE scans for service across multiple RATs (e.g., any of 3GPP, <NUM>, LTE, or <NUM> NR).

<CIT> discloses service recovery techniques for an accessory device.

<CIT> discloses methods for device resource savings during a cellular out-of-service condition.

The matter for which protection is sought is defined in the claims.

The present disclosure may be better understood, and its numerous features and advantages made apparent to those skilled in the art, by referencing the accompanying drawings.

<FIG> illustrate example systems and techniques by which power consumption of two connected UEs in an OOS state can be reduced like in the claimed invention, by only using the first UE to scan for service, while the second UE does not scan for service (e.g., by disabling one or more modems of the second UE associated with the RAT or RATs being scanned). In some embodiments, the first UE may transmit OOS recovery parameters to the second UE via a wireless personal area network (WPAN), allowing the second UE to continue scanning for service in the instance that the second UE becomes unpaired from the first UE, or a signal strength of the WPAN connection between the first and second UEs becomes marginal.

In some scenarios, two UEs that are both configured for wireless communication with at least one radio access network (RAN) via at least a first RAT (e.g., 3GPP, <NUM>, LTE, or <NUM> NR) are connected to one another via a WPAN connection using a wireless technology standard such as Bluetooth. In such scenarios, a first UE (e.g., a smartphone) of the two UEs may maintain a connection to the RAN via the first RAT, while the second UE (e.g., a smartwatch) of the two UEs is tethered to the first UE and operates in a tethering mode. In the tethering mode, the second UE disables one or more modems associated with first RAT communications and instead acquires data or voice services from the first network via its WPAN connection to the first UE. Routing data and voice services to the second UE via the first UE and the WPAN connection in this way generally reduces power consumption of the second UE. However, if the first UE loses its connection to the wireless network while still connected to the second UE, both the first UE and the second UE will, in conventional systems, begin scanning for service, which undesirably results in higher power consumption at both the first and second UEs.

In the claimed invention, the first UE shares one or more OOS recovery parameters (e.g., scan patterns, timers, counters, ping-pong rates, and/or the like) with the second UE so that, in the event the first and second UEs become disconnected or the signal strength between the first and second UEs becomes marginal, the second UE can continue scanning for service (e.g., while executing corresponding OOS recovery protocols) based on the OOS recovery parameters of the first UE. That is, sending the OOS recovery parameters from the first UE to the second UE while the first and second UEs are connected provides at least some continuity between OOS recovery activities performed by the first UE and subsequent OOS recovery activities performed by the second UE.

For example, when scanning for service, a given UE uses significantly more power (e.g., as much as <NUM> times more power) than when the UE is in an otherwise idle state. For UEs with limited power supplies (e.g., battery-powered devices such as smartphones, tablets, or smart watches), it is therefore not feasible for such UEs to continuously scan for service. To reduce the power consumption associated with service acquisition, a UE in the OOS state may only scan for service during a portion of a given time period and remain in an idle state (e.g., a sleep state) for the remainder of that time period. While a UE is in the OOS state, the ratio of the amount of time that the UE scans for service to the amount of time that the UE spends in the idle state is referred to herein as the "scan ratio" of the UE. As will be described, a UE may implement an OOS recovery protocol to dynamically set the scan ratio based on the one or more OOS recovery parameters.

<FIG> illustrates a block diagram of an embodiment of a wireless communication network <NUM> in which a first UE <NUM> is communicatively coupled to a second UE <NUM> and to a RAN <NUM> via a BS <NUM>. In the present example, the first UE <NUM> is communicatively coupled to the BS <NUM> via a wireless network connection <NUM> using a first RAT (e.g., 3GPP, <NUM>, LTE, or <NUM> NR), the wireless network connection <NUM> shown at <FIG> to include a downlink connection <NUM> and an uplink connection <NUM>. The first UE <NUM> is also communicatively coupled to the second UE <NUM> via a WPAN connection <NUM> using a wireless technology standard such as Bluetooth.

In some embodiments, the first UE <NUM> is a mobile communications device, such as a smartphone or tablet, while the second UE <NUM> is a smartwatch. Both the first UE <NUM> and the second UE <NUM> are capable of communicating with the RAN <NUM> using the first RAT. However, in the present example, upon connecting to the first UE <NUM> via the WPAN connection <NUM> (i.e., upon being tethered to the first UE <NUM>), the second UE <NUM> disables one or more modems associated with first RAT communications and instead routes all of its data and voice call activity via the WPAN connection <NUM>, the first UE <NUM>, and the wireless network connection <NUM> to the BS <NUM>. For example, data (e.g., data corresponding to voice services, data services, or OOS recovery parameters) transmitted between the first UE <NUM> and the second UE <NUM> via the WPAN connection <NUM> may be included in the protocol data unit (PDU) of a WPAN packet (e.g., a Bluetooth packet), with the encoding, transmission, and decoding of the WPAN packet being performed according to conventional techniques.

A boundary <NUM> is shown centered around the first UE <NUM>, representing the range within which the first UE <NUM> can maintain its connection to the second UE <NUM> via the WPAN connection <NUM> (i.e., the range within which the second UE <NUM> can remain tethered to the first UE <NUM>). That is, if the second UE <NUM> exits the boundary <NUM>, the signal strength of the connection between the first UE <NUM> and the second UE <NUM> will diminish so that the WPAN connection <NUM> will be lost. While the boundary <NUM> is shown here as being uniform and circular, it should be understood that the illustrated shape of the boundary <NUM> is intended to be illustrative, not limiting, and could instead take other non-circular or non-uniform shapes (e.g., due to interference from objects in the immediate environment of the first UE <NUM>).

As described further below, when the first UE <NUM> becomes disconnected from the BS <NUM> and the RAN <NUM>, the first UE <NUM> enters an OOS state. In the OOS state, the first UE <NUM> sends one or more OOS recovery parameters to the second UE <NUM> while the WPAN connection <NUM> is maintained. In some embodiments, the first UE <NUM> sends one or more of the OOS recovery parameters to the second UE <NUM> periodically. In some embodiments, the first UE <NUM> sends one or more of the OOS recovery parameters to the second UE <NUM> as the respective values of such OOS recovery parameters are updated (e.g., in the case of the ping-pong rate described below, which is updated as the first UE <NUM> switches between OOS and IS states). The second UE <NUM> uses the OOS recovery parameters provided by the first UE <NUM> to execute one or more OOS recovery protocols upon being disconnected from the first UE <NUM> or responsive to determining that the signal strength of the WPAN connection <NUM> is less than a predetermined threshold level. In this way, continuity is provided between OOS recovery activities of the first UE <NUM> and subsequent OOS recovery activities of the second UE <NUM>, which may advantageously decrease power consumption of the second UE <NUM> during OOS recovery, for example.

<FIG> illustrates an example configuration of a UE <NUM>, which may correspond to an embodiment of either of the first UE <NUM> and the second UE <NUM> of the wireless communication network <NUM> of <FIG>, in accordance with some embodiments. In the depicted configuration, the UE <NUM> includes, for each RAT, a radio frequency (RF) interface <NUM>, one or more antenna arrays <NUM>, each having one or more antennas <NUM>, and a corresponding modem of the modem(s) <NUM>. For example, for wireless communications, the UE <NUM> may include a set of one or more antenna arrays <NUM>, one or more RF interface(s) <NUM>, and one or more modem(s) <NUM> to support <NUM> LTE or <NUM> NR signaling with the BS <NUM>.

The UE <NUM> further includes one or more processors <NUM> and at least one memory <NUM> (e.g., which may include one or more non-transitory computer-readable media). The one or more processors <NUM> can include, for example, one or more central processing units (CPUs), graphics processing units (GPUs), artificial intelligence (AI) accelerators or other application-specific integrated circuits (ASICs), and the like. The memory <NUM> can include any of a variety of media used by electronic devices to store data and/or executable instructions, such as random access memory (RAM), read-only memory (ROM), caches, Flash memory, solid-state drive (SSD) or other mass-storage devices, and the like. For ease of illustration and brevity, the term "memory" is used to refer to the "memory <NUM>", but it will be understood that reference to "memory <NUM>" shall apply equally to other types of storage media unless otherwise noted.

The UE <NUM> further includes a user interface module <NUM>. The user interface module <NUM> can be configured to receive inputs from a user of the UE <NUM>. The user interface module <NUM> can include a graphical user interface (GUI) that receives the input information via a touch input. In other instances, the user interface <NUM> includes an intelligent assistant that receives the input information via an audible input. For example, a user may provide inputs via the user interface module <NUM> to manually enable or disable one or more of the modems <NUM>.

The memory <NUM> is used to store one or more software applications in the form of sets of executable software instructions and associated data that manipulate the one or more processors <NUM>, modems <NUM>, RF interfaces <NUM>, user interface module <NUM>, and other components of the UE <NUM> to perform the various functions described herein and attributed to the UE <NUM>. The software includes, for example, one or more system applications <NUM>, a connection manager <NUM>, an operating system <NUM>, and one or more OOS recovery protocols <NUM>.

The system applications <NUM> may include a system manager, such as any form of a control application, software application, signal-processing and control module, code that is native to a particular device, an abstraction module or gesture module, and the like. The system applications <NUM> may also include system components and utilities associated with implementing OOS recovery functions, such as the connection manager <NUM> and the OOS recovery protocols <NUM>.

The connection manager <NUM> manages or directs the UE <NUM> in utilizing one or more connections for communication with a base station, such as an embodiment of the BS <NUM> of <FIG>. The connection manager <NUM> may include, be coupled with, or have access to components for measuring characteristics of a connection, scanning for service, receiving connection parameters from the base station, acquiring a connection, releasing a connection, or the like. In various aspects of adaptive connection management, the connection manager <NUM> may also alter connection parameters, such as to reduce data activity associated with a connection or prevent the acquisition of a connection.

The UE <NUM> executes the OOS recovery protocols <NUM> when scanning for service during the OOS state. As explained above, a tradeoff exists between power consumption in scanning for service and delay in service acquisition (e.g., based on how frequently the UE performs scans). One or more of the OOS recovery protocols <NUM> may determine the scan ratio of the UE <NUM>, setting, for a given time period, a first amount of time during which the UE <NUM> is to scan for service and a second amount of time during which the UE <NUM> is not to scan for service. In some embodiments, when the UE <NUM> is not scanning for service during such a time period, the UE <NUM> may remain in a sleep mode.

For example, one of the OOS recovery protocols <NUM> executed by the UE <NUM> may be an incremental sleep algorithm that causes the UE <NUM> to perform scans for service less frequently as the amount of time during which the UE <NUM> has remained in the current OOS state (referred to herein as the "OOS time") increases. The UE <NUM> may keep track of the amount of time that has passed while in the current OOS state using one or more timers or counters, for example. The incremental sleep algorithm may set a sleep duration based on such timers or counters, the sleep duration defining the amount of time that is to elapse between scans for service performed by the UE <NUM>. The incremental sleep algorithm may increase the sleep duration as the OOS time increases.

As another example, the OOS recovery protocols <NUM> may include a ping-pong rate-based OOS recovery protocol for adjusting the scan ratio used by the UE <NUM> when scanning for service based on the extent to which a UE <NUM> is frequently going in and out of service. For example, the UE <NUM> may determine a ping-pong rate that is representative of the rate at which the UE <NUM> has changed (e.g., historically, over a rolling time window, etc.) between an IS state and an OOS state. For example, the ping-pong rate may be determined based on the duration of the most recent connected time window in which the UE <NUM> was connected to a service (e.g., via the BS <NUM> of <FIG>). In general, the longer the duration of the connected time window, the lower the ping-pong rate. Once the ping-pong rate is determined, the ping-pong rate-based algorithm selects a starting scan ratio for the UE <NUM>, to be used the next time the UE <NUM> goes into the OOS state. More specifically, the starting scan ratio to be used during the next OOS state of the UE <NUM> may be reset to a particular scan ratio of a decreasing sequence of scan ratios used during the previous disconnected time window during which the UE <NUM> was disconnected from service. The decreasing sequence of scan ratios is a sequence in which each scan ratio is less than (or in some cases, the same) as a previous scan ratio in the sequence. The decreasing sequence of scan ratios generally decreases over the course of the sequence with respect to the scan time represented in each scan ratio. The ping-pong rate may indicate which scan ratio in the sequence of scan ratios the current scan ratio should be set to. For instance, a relatively higher ping-pong rate (indicating rapid loss and reacquisition of service) may cause the UE <NUM> to continue using the most recently used scan ratio of the sequence as if the most recent service reacquisition did not happen. A medium ping-pong rate may instead cause the scan ratio to be reset to a mid-point of the decreasing sequence of scan ratios used during the last disconnected time window. A relatively lower ping-pong rate (indicating infrequent loss and acquisition of service) may cause the scan ratio to be reset back to the initial scan ratio of the sequence. In this manner, the ping-pong rate-based OOS recovery protocol may allow for efficient reductions in scan ratios when the UE <NUM> is frequently going in and out of service.

The memory <NUM> may further store one or more OOS recovery parameters <NUM>. The OOS recovery parameters <NUM> may include any of, for example, one or more timers or counters for tracking the amount of time during which the UE <NUM> (or a connected UE) has been in the OOS state, a ping-pong rate, or other applicable parameters. The OOS recovery parameters <NUM> are used in executing one or more of the OOS recovery protocols <NUM>, as described in the previous examples.

In some embodiments, the UE <NUM> generates the OOS recovery parameters <NUM> while scanning for service and sends the OOS recovery parameters <NUM> to a connected UE (e.g., the second UE <NUM> of <FIG>), if any connected UE is present. This allows the connected UE to resume scanning for service based on the actions already taken by the UE <NUM> while scanning for service.

In some embodiments, the UE <NUM> receives the OOS recovery parameters <NUM> from a connected UE (e.g., the first UE <NUM> of <FIG>). This allows the UE <NUM> to resume scanning for service based on the actions already taken by the connected UE while scanning for service.

<FIG> illustrates a block diagram of an example in which the first UE <NUM> of the wireless communication network <NUM> is no longer connected to the BS <NUM> via the wireless network connection <NUM> of <FIG> (or any other BS), the first UE <NUM> and the second UE <NUM> are still connected via the WPAN connection <NUM> (i.e., while the second UE <NUM> is still tethered to the first UE <NUM> and is in the tethering mode), and the signal strength of the WPAN connection <NUM> is not marginal. In the present example, the first UE <NUM> is in an OOS state. In the OOS state, the first UE <NUM> scans for service to reestablish the wireless network connection <NUM> with the BS <NUM> or to establish a new wireless network connection via another BS. In some embodiments, while in the OOS state, the first UE <NUM> scans for service from multiple RANs, across multiple corresponding RATs (e.g., any of 3GPP, <NUM>, LTE, or <NUM> NR), including the first RAT. In some embodiments, when scanning for service, the first UE <NUM> performs scans of frequencies stored in an acquisition database (ACQ DB) of the first UE <NUM> in addition to full band scans on one or more RATs, with scan intervals being defined by one or more OOS recovery protocols (e.g., the OOS recovery protocols <NUM>) executed at the first UE <NUM>. The ACQ DB of the first UE <NUM> includes information related to frequencies on which the first UE <NUM> is most likely to find a signal where service may be acquired within each public land mobile network (PLMN) that is accessible by the first UE <NUM> for each RAT supported by each PLMN. In some embodiments, the ACQ DB includes a list of frequencies that are each associated with a PLMN identifier and a RAT identifier.

In conventional systems, the second UE <NUM> would typically attempt to find network service using the first RAT upon determining that the first UE <NUM> is in the OOS state. However, it is generally inefficient for both the first UE <NUM> and the second UE <NUM> to scan for service, since using both devices to scan for service only provides a marginal decrease in the delay in reestablishing service (once service is available again), while significantly increasing the power consumption of both the first UE <NUM> and the second UE <NUM>. In the claimed invention, in order to avoid such inefficiencies, the second UE <NUM> does not scan for service while connected to the first UE <NUM> via the WPAN connection <NUM> (i.e., while the second UE <NUM> is tethered to the first UE <NUM> and is in the tethering mode), as long as the strength of the WPAN connection <NUM> is non-marginal (e.g., for as long as the instantaneous or average signal strength of the WPAN connection <NUM> remains above a predetermined threshold level). In some embodiments, the second UE <NUM> disables one or more modems associated with the RATs for which service is being scanned when the first UE is in the OOS state and while the signal strength of the WPAN connection <NUM> is non-marginal. The first UE <NUM> generates OOS recovery parameters (e.g., the OOS recovery parameters <NUM> of <FIG>) while in the OOS state. In some embodiments, the first UE <NUM> uses at least some of the OOS recovery parameters as inputs to one or more OOS recovery protocols (e.g., the OOS recovery protocols <NUM> of <FIG>). In some embodiments, the first UE <NUM> additionally or alternatively sends the OOS recovery parameters to the second UE <NUM> while the first UE <NUM> is in the OOS state. In some embodiments, the first UE <NUM> sends the OOS recovery parameters to the second UE <NUM> periodically (e.g., at a predetermined rate) while the first UE <NUM> is in the OOS state.

Because the second UE <NUM> receives the OOS recovery parameters from the first UE <NUM>, the second UE <NUM> is able to continue scanning for service where the first UE <NUM> left off in the event that the second UE <NUM> becomes disconnected from the first UE <NUM> (i.e., if the WPAN connection <NUM> is lost or disabled). For example, if the second UE <NUM> becomes disconnected from the first UE <NUM> while the first UE <NUM> is in the OOS state, then the second UE <NUM> activates at least one modem (e.g., one or more of the modems <NUM> of <FIG>) configured to communicate using the first RAT, then the second UE <NUM> begins scanning for service according to one or more OOS recovery protocols (e.g., the OOS recovery protocols <NUM> of <FIG>). Rather than having to begin scanning for service without any prior information regarding actions that have already been taken by the first UE <NUM> when scanning for service, in the claimed invention, the second UE <NUM> is able to continue scanning for service based on the OOS recovery parameters received from the first UE <NUM>.

For example, the second UE <NUM> leverages scan patterns that have already been executed by the first UE <NUM>, as indicated in the OOS recovery parameters, such that the second UE <NUM> continues execution of the OOS recovery protocol(s) as though those scan patterns had already been performed by the second UE <NUM>. In some embodiments, one or more of the OOS recovery protocols (e.g., an incremental sleep algorithm or a ping-pong rate-based OOS recovery protocol of the OOS recovery protocols <NUM>) initially (i.e., in an initial phase) require a UE to scan multiple frequency bands at a relatively high rate, and over time reduce the scan ratio defining a ratio of the scan duration to the sleep duration used when scanning for service. Scanning frequency bands at a relatively higher rate corresponds to higher power consumption. So, by leveraging scan patterns previously performed by the first UE <NUM> based on the OOS recovery parameters (instead of starting the associated OOS recovery protocol(s) in their initial, high scan ratio phase), the power consumption of the second UE <NUM> is reduced when attempting to acquire service after disconnecting from the first UE <NUM>.

As another example, the OOS recovery parameters provided by the first UE <NUM> can include PLMN information acquired during one or more early stages of the OOS recovery protocol executed by the first UE <NUM>, such that the second UE <NUM> is able to begin scanning for service sooner, rather than having to perform an initial PLMN selection and PLMN search.

<FIG> illustrates a block diagram of an example in which the first UE <NUM> of the wireless communication network <NUM> is no longer connected to the BS <NUM> via the wireless network connection <NUM> of <FIG> (or any other BS), and the signal strength of the WPAN connection <NUM> is marginal (e.g., inconsistent, below a predetermined threshold level, or both) due to the second UE <NUM> being at or near the boundary <NUM>. In the present example, the first UE <NUM> is in the OOS state, as described previously.

In response to determining that the signal strength of the WPAN connection <NUM> is marginal, the second UE <NUM> activates at least one modem (e.g., one or more of the modems <NUM> of <FIG>) configured to communicate using one or more RATs (e.g., including the first RAT), then the second UE <NUM> begins scanning for service according to one or more OOS recovery protocols (e.g., OOS recovery protocols <NUM> of <FIG>).

In some embodiments, the second UE <NUM> receives OOS recovery parameters (e.g., the OOS recovery parameters <NUM> of <FIG>) from the first UE <NUM> while the first UE <NUM> is in the OOS state and prior to determining that the signal strength of the WPAN connection <NUM> is marginal. In such embodiments, rather than having to begin scanning for service without any prior information regarding actions that have already been taken by the first UE <NUM> when scanning for service, the second UE <NUM> is able to continue scanning for service based on the OOS recovery parameters received from the first UE <NUM>, as described above. For example, many OOS recovery protocols involve scanning for service more frequently in one or more early stages of the OOS recovery protocol, and scanning for service less frequently in one or more later stages of the OOS recovery protocol. According to various embodiments, the stage of the OOS recovery protocol can be determined based on one or more OOS counter values or OOS timer values of the OOS recovery parameters that indicate the number of scans for service performed or the amount of time spent in the OOS state, or based on OOS recovery protocol state information included in the OOS recovery parameters that indicate the current stage of the OOS recovery protocol. By utilizing prior information, such as the OOS recovery parameters, indicative of actions that have already been taken by the first UE <NUM> when scanning for service in the OOS state, the second UE <NUM> may skip the early stages of the OOS recovery protocol to avoid unnecessarily repeating the more frequent scans for service associated with such early stages.

<FIG> is a flow diagram of a method <NUM> of OOS recovery following loss of service via a wireless network connection using a first RAT (e.g., 3GPP, <NUM>, LTE, or <NUM> NR) by a first UE, where the first UE and a second UE are initially paired via a WPAN connection. In the claimed invention, OOS recovery parameters are shared between the first UE and the second UE when the first UE enters the OOS state. The method <NUM> is implemented in some embodiments of the wireless communication network <NUM> of <FIG>, <FIG>, and <FIG>, and in connection with some embodiments of the UE <NUM> of <FIG>. Accordingly, like elements of <FIG> are referred to in the present example using like numerals. At block <NUM>, the first UE <NUM> detects an OOS condition with respect to the first RAT. For example, the OOS condition is typically triggered by losing a wireless network connection to a BS associated with a RAN, such as the wireless network connection <NUM> to the BS <NUM> associated with the RAN <NUM>.

At block <NUM>, responsive to detecting the OOS condition, the first UE <NUM> executes one or more OOS recovery protocols, such as the OOS recovery protocols <NUM>. In some embodiments, the first UE <NUM> scans for service across multiple RATs (e.g., any of 3GPP, <NUM>, LTE, or <NUM> NR), including the first RAT. In some embodiments, when scanning for service, the first UE <NUM> performs scans of frequencies stored in an acquisition database (ACQ DB) of the first UE <NUM> in addition to full band scans on one or more RATs, with scan intervals being defined by the one or more OOS recovery protocols executed at the first UE <NUM>.

The second UE <NUM> does not automatically attempt to execute the OOS recovery protocols or scan for service, and one or more modems of the second UE <NUM> that are configured for communicating via the RATs being scanned by the first UE <NUM> are disabled (e.g., turned off or kept in an idle state). However, in some embodiments, a user may manually enable such modems to cause the second UE <NUM> to scan for service during block <NUM>.

At block <NUM>, the first UE <NUM> determines whether service (e.g., via the first RAT or another RAT for which service was scanned at block <NUM>) has been reestablished upon execution of the OOS recovery protocol(s). If the first UE <NUM> determines that service has been reestablished, the method <NUM> ends. Otherwise, if the first UE <NUM> determines that service has not been reestablished, the method <NUM> proceeds to block <NUM>.

At block <NUM>, while continuing to execute the OOS recovery protocols, the first UE <NUM> transmits OOS recovery parameters to the second UE <NUM> (e.g., via the WPAN connection <NUM>). In some embodiments, the first UE <NUM> transmits the OOS recovery parameters to the second UE <NUM> periodically (e.g., at a predetermined rate).

At block <NUM>, the second UE <NUM> determines whether the WPAN connection <NUM> between the first UE <NUM> and the second UE <NUM> has been lost. For example, the WPAN connection <NUM> between the first UE <NUM> and the second UE <NUM> can be lost if the signal strength of the WPAN connection <NUM> drops to a sufficiently low level (e.g., due to the second UE <NUM> leaving the wireless range of the first UE <NUM> with respect to the wireless technology standard used to implement the WPAN connection <NUM>) or if a user manually disables the WPAN communications of either or both of the first UE <NUM> and the second UE <NUM>. If the second UE <NUM> determines that the WPAN connection <NUM> has been lost (i.e., the first UE <NUM> is no longer connected to the second UE <NUM>), the method proceeds to block <NUM>. Otherwise, if the second UE <NUM> determines that the WPAN connection <NUM> has not been lost, the method <NUM> proceeds to block <NUM>.

At block <NUM>, the second UE <NUM> activates one or more modems configured for communication via one or more RATs (e.g., including the first RAT) and uses the one or more modems to execute one or more OOS recovery protocols (e.g., the OOS recovery protocols <NUM>). The second UE <NUM> uses the OOS recovery parameters provided by the first UE <NUM> as a basis for scanning for service. For example, the second UE <NUM> may set a scan ratio for scanning for service based on one or more timers or counters or based on a ping-pong rate included in the OOS recovery parameters. In some embodiments, the second UE <NUM> scans for service across multiple RATs (e.g., any of 3GPP, <NUM>, LTE, or <NUM> NR), including the first RAT. In some embodiments, when scanning for service, the second UE <NUM> performs scans of frequencies stored in an acquisition database (ACQ DB) of the second UE <NUM> in addition to full band scans on one or more RATs, with scan intervals being defined by the one or more OOS recovery protocols executed at the second UE <NUM>.

It should be understood that the first UE <NUM> will continue scanning for service in parallel with block <NUM> (e.g., performing blocks <NUM> and <NUM> of the method <NUM>) upon disconnection of the second UE <NUM>, typically until the first UE <NUM> has successfully regained service.

At block <NUM>, the second UE <NUM> determines whether service (e.g., via the first RAT or another RAT for which service was scanned at block <NUM>) has been reestablished upon execution of the OOS recovery protocol(s). If the second UE <NUM> determines that service has been reestablished, the method <NUM> ends. Otherwise, if the second UE <NUM> determines that service has not been reestablished, the method <NUM> proceeds to block <NUM>.

At block <NUM>, if the WPAN connection <NUM> between the second UE <NUM> and the first UE <NUM> is reestablished, the method <NUM> proceeds to block <NUM>. Otherwise, if the WPAN connection <NUM> is not reestablished, the method returns to block <NUM>. For example, the WPAN connection <NUM> can be reestablished due to the second UE <NUM> reentering the wireless range of the first UE <NUM> or due to the user reactivating WPAN communications of the first UE <NUM>, the second UE <NUM>, or both.

At block <NUM>, the second UE <NUM> determines whether the signal strength of the WPAN connection <NUM> between the first UE <NUM> and the second UE <NUM> is less than a predetermined threshold level. For example, the signal strength of the WPAN connection <NUM> may fall to below the predetermined threshold level (without the WPAN connection <NUM> being lost entirely) due to an increase in the distance between the first UE <NUM> and the second UE <NUM> (e.g., such that the second UE is disposed near the boundary <NUM>, as shown previously in <FIG>). If the second UE <NUM> determines that the signal strength of the WPAN connection <NUM> is less than the predetermined threshold level, the method <NUM> proceeds to block <NUM>. Otherwise, if the second UE <NUM> determines that the signal strength of the WPAN connection <NUM> is at or above the predetermined threshold level, the method <NUM> returns to block <NUM>.

At block <NUM>, the second UE <NUM> activates one or more modems configured for communication via one or more RATs (e.g., including the first RAT) and both the first UE <NUM> and the second UE <NUM> execute one or more OOS recovery protocols to scan for service. As described above, the second UE <NUM> uses the OOS recovery parameters provided by the first UE <NUM> as a basis for scanning for service. It may be beneficial to use both the first UE <NUM> and the second UE <NUM> to scan for service in response to determining that the signal strength of the WPAN connection <NUM> is less than the predetermined threshold level, since such a determination can be predictive of an impending loss of the WPAN connection <NUM>.

At block <NUM>, the second UE <NUM> determines whether service (e.g., via the first RAT or another RAT for which service was scanned at block <NUM>) has been reestablished upon execution of the OOS recovery protocol(s) by the first UE <NUM> and the second UE <NUM>. If the second UE <NUM> determines that service has been reestablished, the method <NUM> ends. Otherwise, if the second UE <NUM> determines that service has not been reestablished, the method <NUM> returns to block <NUM>.

In some embodiments, certain aspects of the techniques described above may be implemented by one or more processors of a processing system executing software. The software comprises one or more sets of executable instructions stored or otherwise tangibly embodied on a non-transitory computer-readable storage medium.

Such storage media can include, but is not limited to, optical media (e.g., compact disc (CD), digital versatile disc (DVD), Blu-Ray disc, magnetic media (e.g., floppy disc, magnetic tape, or magnetic hard drive), volatile memory (e.g., RAM or cache), non-volatile memory (e.g., ROM or Flash memory), or microelectromechanical systems (MEMS)-based storage media.

Claim 1:
A method comprising:
receiving, from a first user equipment (<NUM>), UE, by a second UE (<NUM>) responsive to the first UE entering an out-of-service, OOS, state, at least one OOS recovery parameter via a wireless personal area network, WPAN, connection (<NUM>);
scanning, by the second UE, while the first UE is in an OOS state and responsive to determining that the WPAN connection is lost or a signal strength of the WPAN connection is less than a predetermined threshold level, a plurality of frequency bands for service based on the at least one OOS recovery parameter; and
disabling, by the second UE, scanning of the plurality of frequency bands for service while the first UE is in an OOS state and while the signal strength of the WPAN connection is above the predetermined threshold level.