Connectivity loss detection and re-association

Abstract

The embodiment of the invention relates to equipment, a method, a device and a computer readable storage medium for connectivity loss detection and re-association. In the method, a network device sends a first configuration to a device set, the first configuration comprising a first set of duty cycles for querying a plurality of terminal devices associated with the device set. A network device receives a set of measurement reports for a plurality of terminal devices from a set of devices.

Description

TECHNICAL FIELD

[0001] Various example embodiments of the present disclosure generally relate to the field of telecommunications, and in particular to devices, methods, apparatuses, and computer-readable storage media for connectivity loss detection and re-association. BACKGROUND

[0002] With energy harvesting technology, a device can harvest energy present in the surrounding environment. This can allow the device to use the harvested energy and operate in a passive mode. Ambient Internet of Things (IoT) is a communication service that supports energy harvesting, and has been widely used in various vertical industries. Tags are a typical example of ambient IoT (also known as passive IoT (PIoT)) devices, and have limited capabilities. Tags can be connected or associated with a network through a reader. The tag and / or the reader can not always be statically located at one location or one site. Due to the mobility of the reader and / or the tag, the tag can lose its connectivity to the network. SUMMARY

[0003] In a first aspect of the present disclosure, a network device is provided. The network device includes at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the network device to at least perform: sending, to a set of devices, a first configuration including a first set of duty cycles for querying a plurality of terminal devices associated with the set of devices; and receiving, from the set of devices, a set of measurement reports for the plurality of terminal devices.

[0004] In a second aspect of the present disclosure, a device is provided. The second device includes at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the device to at least perform: receiving, from a network device, a first configuration including a first duty cycle for querying a terminal device; sending, to the terminal device, a query using the first duty cycle; determining a measured power of a signal backscattered by the terminal device as a response to the query; and sending, to the network device, a measurement report for the terminal device based on a measured power level of the backscattered signal.

[0005] In a third aspect of the present disclosure, a method is provided. The method includes: sending, to a set of devices, a first configuration including a first set of duty cycles for querying a plurality of terminal devices associated with the set of devices; and receiving, from the set of devices, a set of measurement reports for the plurality of terminal devices.

[0006] In a fourth aspect of the disclosure, a method is provided. The method comprises receiving, from a network device, a first configuration comprising a first duty cycle for querying a terminal device; transmitting, to the terminal device, a query using the first duty cycle; determining a measured power level of a signal backscattered by the terminal device in response to the query; and transmitting, to the network device, a measurement report for the terminal device based on the measured power level of the backscattered signal.

[0007] In a fifth aspect of the disclosure, an apparatus is provided. The apparatus comprises means for transmitting, to a set of devices, a first configuration comprising a first set of duty cycles for querying a plurality of terminal devices associated with the set of devices; and means for receiving, from the set of devices, a set of measurement reports for the plurality of terminal devices.

[0008] In a sixth aspect of the disclosure, an apparatus is provided. The apparatus comprises means for receiving, from a network device, a first configuration comprising a first duty cycle for querying a terminal device; means for transmitting, to the terminal device, a query using the first duty cycle; means for determining a measured power level of a signal backscattered by the terminal device in response to the query; and means for transmitting, to the network device, a measurement report for the terminal device based on the measured power level of the backscattered signal.

[0009] In a seventh aspect of the disclosure, a computer readable medium is provided. The computer readable medium comprises instructions stored thereon for causing an apparatus to perform at least the method according to the third aspect.

[0010] In an eighth aspect of the disclosure, a computer readable medium is provided. The computer readable medium comprises instructions stored thereon for causing an apparatus to perform at least the method according to the fourth aspect.

[0011] It should be understood that the Summary is not intended to identify key or essential features of embodiments of the disclosure, nor is it intended to limit the scope of the disclosure. Other features of the disclosure will be readily apparent from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0012] Some example embodiments will now be described with reference to the drawings, in which:

[0013] Figure 1 An example communication environment in which example embodiments of the disclosure can be implemented is shown;

[0014] Figure 2 A high level signaling diagram of a procedure for connectivity loss detection according to some example embodiments of the disclosure is shown;

[0015] Figure 3A flow diagram showing an example method for connectivity detection according to some example embodiments of the present disclosure is shown;

[0016] Figure 4 An example configuration of a query frequency for a terminal device according to some example embodiments of the present disclosure is shown;

[0017] Figure 5 A flow diagram showing an example process for connectivity detection and re-association according to some example embodiments of the present disclosure is shown;

[0018] Figure 6 A flow diagram showing an example method for connectivity detection according to some example embodiments of the present disclosure is shown;

[0019] Figure 7 A flow diagram showing an example process for connectivity detection according to some example embodiments of the present disclosure is shown;

[0020] Figure 8 A signaling diagram showing a process for connectivity detection and re-association according to some example embodiments of the present disclosure is shown;

[0021] Figure 9 A simplified block diagram of a device suitable for implementing example embodiments of the present disclosure is shown; and

[0022] Figure 10 A block diagram of an example computer readable medium according to some example embodiments of the present disclosure is shown.

[0023] In all of the drawings, like or similar reference numerals are used to refer to like or similar elements throughout. DETAILED DESCRIPTION

[0024] The principles of the present disclosure will now be described with reference to some example embodiments. It should be understood that these embodiments are described for illustrative purposes only and are helpful in understanding and implementing the present disclosure, but are not intended to limit the scope of the present disclosure in any way. The embodiments described herein can be implemented in various ways other than those described below.

[0025] In the following description and claims, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0026] References in the present disclosure to “one embodiment,” “an embodiment,” “example embodiments,” and the like indicate that the embodiment described can include a particular feature, structure, or characteristic, but every embodiment can not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Furthermore, when a particular feature, structure, or characteristic is described in connection with an example embodiment, it is submitted that embodiments can include such features, structures, or characteristics whether or not they are described in connection with particular embodiments.

[0027] It should be understood that although the terms “first” and “second” and the like can be used herein to describe various elements, these elements should not be limited to these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element without departing from the scope of the example embodiments. As used herein, the term “and / or” includes any or all combinations of one or more of the associated listed terms.

[0028] As used herein, “at least one of ” and “one or more of ” and similar phrases, where the list of two or more elements is preceded by “at least one of” or “one or more of,” means at least any one of the listed elements, or any combination of any two or more of the listed elements.

[0029] As used herein, unless expressly stated otherwise, performing a step “in response to” an event does not indicate that the step is performed immediately upon occurrence of the event, but can include one or more intervening steps.

[0030] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes” and / or “including,” when used herein, specify the presence of stated features, elements and / or components, but do not preclude the presence or addition of one or more other features, elements, components and / or combinations thereof.

[0031] As used in this application, the term “circuitry” can refer to one or more or all of the following: (a) hardware-only circuitry implementations (such as implementations in pure analog and / or digital circuitry) and (b) combinations of hardware circuits and software, such as (as applicable): (i) combinations of analog and / or digital hardware circuits with software / firmware and (ii) any portion of hardware processor with software (including digital signal processor(s), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and (c) hardware circuit(s) and / or processor(s), such as microprocessor(s) or a portion of microprocessor(s), that require software (e.g., firmware) for operation, but that software can not be present when it is not needed for operation.

[0032] This definition of circuit applies to all uses of this term in this application. As a further example, as used in this application, the term "circuit" also covers a implementation of only hardware circuit or processor (or processors), or hardware circuit or processor portions thereof, and their accompanying software and / or firmware that work together to cause an apparatus, like a mobile device or server, to perform various functions described herein. For example, as applicable, the term "circuit" covers an implementation in a baseband integrated circuit or processor integrated circuit for a mobile device or similar integrated circuits in a cellular network device or other computing or network device.

[0033] As used herein, the term "communication network" refers to a network following any suitable communication standards, such as New Radio (NR), Long Term Evolution (LTE), Long Term Evolution Advanced (LTE-A), Wideband Code Division Multiple Access (WCDMA), High Speed Packet Access (HSPA), Narrow Band Internet of Things (NB-IoT), etc. In addition, the communication between the terminal device and the network device in the communication network can be performed according to any suitable generation communication protocol, including but not limited to, the first generation (1G), the second generation (2G), 2.5G, 2.75G, the third generation (3G), the fourth generation (4G), 4.5G, the fifth generation (5G), the sixth generation (6G) communication protocol, and / or any other protocol currently known or developed. Embodiments of the present disclosure can be applied in various communication systems. In view of the rapid development in communications, it is inevitable that future types of communication technology and systems can be implemented, which can implement the present disclosure. The scope of the present disclosure should not be considered as being limited to the above-described systems.

[0034] As used herein, the term “network device” refers to a node in a communication network via which terminal devices access the network and receive services therefrom. Depending on the terminology applied, the network device can refer to a base station (BS) or an access point (AP), e.g., a Node B (NodeB or NB), an evolved NodeB (eNodeB or eNB), a New Radio (NR) NB (also referred to as gNB), a remote radio unit (RRU), a radio head (RH), a remote radio head (RRH), a relay, an integrated access and backhaul (IAB) node, a low power node (such as a femto, pico), a non-terrestrial network (NTN) or non-terrestrial network device (such as satellite network devices, low earth orbit (LEO) satellites, and geosynchronous earth orbit (GEO) satellites), a flying aircraft network device, etc. In some example embodiments, a radio access network (RAN) split architecture includes a central unit (CU) and a distributed unit (DU) at an IAB donor node. An IAB node includes a mobile termination (IAB-MT) portion similar to a UE towards a parent node, and the DU portion of the IAB node is similar to a base station towards a next hop IAB node.

[0035] The term “terminal device” refers to any end device with wireless communication capability. By way of example, and without limitation, a terminal device can refer to a communication device, user equipment (UE), subscriber station (SS), portable subscriber station, mobile station (MS), or access terminal (AT). A terminal device can include, but is not limited to, a mobile phone, a cellular phone, a smart phone, a voice over Internet Protocol (VoIP) phone, a wireless local loop phone, a tablet, a wearable terminal device, a personal digital assistant (PDA), a portable computer, a desktop computer, an image capture terminal device such as a digital camera, a game terminal device, a music storage and playback appliance, a vehicle-mounted wireless terminal device, a wireless endpoint, a mobile station, a laptop-embedded equipment (LEE), a laptop-mounted equipment (LME), a USB dongle, a smart device, a wireless customer-premise equipment (CPE), an Internet of Things (IoT) device, a watch or other wearable device, a head-mounted display (HMD), a vehicle, a drone, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in an industrial and / or an automated processing chain context), consumer electronics, devices operating on a business and / or industrial wireless network, etc. A terminal device can also correspond to a mobile termination (MT) portion of an IAB node (also referred to as a relay node). In the following description, the terms “terminal device,” “communication device,” “terminal,” “user equipment,” and “UE” can be used interchangeably.

[0036] In some example embodiments, the terminal device can comprise an environmental / passive IoT device, such as a tag. The passive IoT device can collect energy from both third generation partnership project (3GPP) and non-3GPP devices. For example, the passive IoT device can be illuminated by an energy signal and backscatter information to a device, such as a reader, that is capable of receiving and processing the signal backscattered by the passive IoT, such as a tag.

[0037] Devices powered by energy harvesting, such as passive IoT devices, can also be referred to as energy harvesting devices, which can use energy harvested from radio waves or any other form of energy that can be harvested in its (particular) deployment scenario. If the energy is collected from radio waves, the output power of the energy harvester can be from a few microwatts to tens of microwatts. If a solar panel is used to harvest energy from the sun and / or light, due to the small size of the solar panel, the output power of the energy harvester can be less than 1 milliwatt.

[0038] Some energy harvesting devices can have an active transmission circuit. After harvesting energy, such energy harvesting devices can use the active circuit for transmission, similar to a conventional transmitter. Some other energy harvesting devices, also referred to as passive devices, can not have an active transmission circuit and backscatter signals in a passive mode.

[0039] Passive IoT services have been widely used in various vertical industries, including logistics, manufacturing, transportation, energy industry, etc. Enabling passive IoT devices in both public networks and private networks can benefit the 5G or even 6G ecosystem. Passive IoT can be applied in the following scenarios: 1) scenarios where devices operate in extreme environmental conditions such as high pressure, extremely high or low temperature, humid environment, vibration, etc.; 2) scenarios that require ultra-low complexity (or cost), very small terminal size (or form factor) (e.g., mm in thickness), maintenance-free, and longer life cycle, etc.; 3) other scenarios where battery-driven devices are not applicable. Therefore, it can be necessary to support passive IoT using battery-less devices or devices with limited energy storage capability (e.g., using capacitors).

[0040] For passive IoT, radio frequency identification (RFID) solutions and backscatter technology can be used together, also referred to as backscatter RFID solutions. The goal of passive IoT is to enhance coverage for backscatter RFID solutions using 3GPP technologies, as well as to introduce new solutions with advanced features, such as harvesting energy from dedicated sources or environmental energy sources and using the energy efficiently for IoT-type data transmission. Some related use cases, traffic scenarios, and key performance indicators (KPIs) can be defined in 3GPP. The considered devices cover both battery-less type devices or devices with limited energy storage capability, and can provide energy via radio waves harvesting, light, motion, etc.

[0041] For passive IoT with energy harvesting capability or environmental energy-enabled IoT, low rate and low complexity can be targeted, and both battery-less devices and devices with small batteries can need to be supported. Furthermore, both active and passive IoT devices can need to be supported. Radio access network (RAN) design targets can be based on the identified deployment scenarios and their characteristics for the relevant use cases, e.g., can include power consumption, complexity, coverage, data rate, and positioning accuracy.

[0042] In some scenarios, tags and / or readers can not always be statically located at one location or premises. Due to the mobility of the readers and / or tags, the tags can lose their connectivity with the network. Since such low-end devices that can support use cases such as warehouse inventory management can not require “make before break” functionality, there can be no need to develop mechanisms and allocate resources in advance to maintain connectivity and service continuity as in traditional new radio (NR) devices.

[0043] Therefore, there can be some challenges in tag association. For example, it can be difficult for a tag to know that the connection with the original associated reader is lost. Meanwhile, it can be difficult for a reader to know that a tag is out of its coverage and when to start a re-association or re-attachment procedure.

[0044] Example embodiments of the present disclosure propose a scheme for connectivity loss detection. The scheme allows a device (such as a reader) that can be connected to a set of terminal devices (such as tags) and is capable of illuminating or transmitting a stimulus signal to the set of terminal devices to actively detect the loss of connection with the terminal devices and inform the network to start a re-connection procedure with the terminal devices. With the scheme, a network device (such as a gNB) transmits to a set of devices associated with a plurality of terminal devices a configuration including a set of duty cycles for querying the terminal devices (also referred to as query duty cycles). The set of devices uses the duty cycles to query the associated terminal devices and transmits to the network device a measurement report for the terminal devices that can be generated based on responses from the terminal devices to the queries.

[0045] Using the configuration of the query duty cycles, multiple readers can actively query specific tags and report the measured signal power for the tags and / or information about the lost tags. Based on such reports, the network can re-associate the tags with different readers without losing connectivity. Therefore, the events of connectivity loss between the tags and the set of readers can be reduced, and the reader and / or tag mobility can be supported.

[0046] Figure 1An example communication environment 100 in which example embodiments of the present disclosure can be implemented is shown. In the communication environment 100, a network device 110 serves a coverage area 115. Examples of the network device 110 can include a base station in a cellular network, and the coverage area 115 can be a cell served by the base station. Alternatively, the network device 110 can operate as an access point or other network device.

[0047] A plurality of terminal devices 120_1,..., 120_K,..., 120_M (individually or collectively referred to as terminal devices 120), where K and M represent positive integers and K < M, are located in the coverage area 115. In examples, the terminal devices 120 are capable of harvesting ambient energy from different energy sources, such as mechanical vibrations, electromagnetic sources, light, sound, air flow, heat, temperature variations, etc., and converting the ambient energy into usable electrical energy. For example, the terminal devices 120 can harvest energy from an electromagnetic energy source 125, which can be a 3GPP or non-3GPP ambient energy source.

[0048] Examples of the terminal devices 120 can include devices with limited capabilities, such as tags or RFID tags or wireless devices (e.g., sensors) with tags. The terminal devices 120 can be provided with a transceiver (or receiver and transmitter) to receive and transmit (or backscatter) signals and with or without a power source (e.g., in the form of a battery). Alternatively or additionally, the terminal devices 120 can operate as slightly more intelligent devices with microprocessors capable of performing some limited processing after receiving signals and / or before transmitting signals. The terminal devices 120 can operate as other more intelligent wireless devices, such as more intelligent IoT devices. For discussion purposes, some example embodiments will be discussed by using tags as examples of the terminal devices 120.

[0049] The communication environment 100 can also include devices 130_1, 130_2,..., 130_N (individually or collectively referred to as devices 130) that provide corresponding coverage areas 135_1,..., 135_N (individually or collectively referred to as coverage areas 135), where N represents a positive integer. The devices 130 can communicate with both the network device 110 and the terminal devices 120 within their coverage areas 135. For example, the device 130_1 can serve the coverage area 135_1 and be associated with the terminal devices 120_1, 120_2,..., 120_K within its served coverage area 135_1.

[0050] Device 130 can be any device capable of illuminating a signal and decoding a signal backscattered by terminal device 120. Examples of device 130 can include a reader or RFID reader, which can receive a signal transmitted (or backscattered) by an associated terminal device 120. Device 130 can be provided in a monostatic or bistatic configuration. In a monostatic configuration, device 130 (e.g., a reader) can both illuminate and receive a signal. In a bistatic configuration, device 130 can include two distributed units or modules (e.g., an illuminator / exciter and a reader), one for signal illumination and the other for signal reception. Thus, terminal device 120 can be connected or associated with a network through a particular device 130, such as a reader (in a monostatic configuration) or a pair of an illuminator and a reader (in a bistatic configuration). Although some example embodiments are discussed in a monostatic scenario, these embodiments are also applicable to a bistatic scenario.

[0051] Device 130 can operate as other wireless devices for signal illumination and reception, which can include terminal devices such as UEs and network devices such as base stations. For discussion purposes, some example embodiments will be discussed by taking a reader as an example of device 130.

[0052] It should be appreciated that Figure 1 The number of devices shown in FIG. 1 is for illustrative purposes only and is not intended as any limitation. Communication environment 100 can include any suitable number of network devices 110, terminal devices 120, and associated (or attached) devices 130. Any suitable number of terminal devices 120 and associated devices 130 can be located in a coverage area 115 of network device 110, and any suitable number of terminal devices 120 can be located in a coverage area 135 of device 130.

[0053] Communications in communication environment 100 can be implemented in accordance with any suitable communication protocol(s), including but not limited to cellular communication protocols of first generation (1G), second generation (2G), third generation (3G), fourth generation (4G), fifth generation (5G), sixth generation (6G), etc., wireless local area network communication protocols such as Institute of Electrical and Electronics Engineers (IEEE) 802.11, and / or any other protocol that is currently known or developed in the future. Moreover, communications can utilize any suitable wireless communication techniques, including but not limited to: code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), frequency division duplexing (FDD), time division duplexing (TDD), multiple-input multiple-output (MIMO), orthogonal frequency division multiple access (OFDM), discrete Fourier transform spread OFDM (DFT-s-OFDM), RFID, and / or any other techniques that are currently known or developed in the future.

[0054] In the environment 100, the terminal device 120_1 can initially be associated with (or connected or attached with) the device 130_1, which can maintain a list of terminal devices 120_1, 120_2, …, 120_K associated or connected therewith. The connectivity can be maintained for a configured time T. If the terminal devices 120_1, 120_2, …, 120_K do not transmit any data during this time T, the connectivity information can be terminated. In this case, an association procedure can be performed between the terminal devices 120_1, 120_2, …, 120_K and the device 130_1. However, during this time T, it can be necessary to maintain the connectivity between the terminal devices 120_1, 120_2, …, 120_K and the device 130_1 to enable the terminal devices 120_1, 120_2, …, 120_K to communicate whenever they have data to transmit.

[0055] In some scenarios, the terminal devices 120 and / or the devices 130 can not be statically located at one location. Due to the mobility of the terminal devices 120 and / or the devices 130, the terminal devices 120 can lose their connectivity with the network. For example, as shown, the terminal device 120_1 is moving out of the coverage area 135_1 of the device 130_1 and towards the coverage area 135_2 of the device 130_2. Thus, the terminal device 120_1 can lose connectivity with the network. Since the terminal device 120_1 can be limited in its capabilities, the network (e.g., the network device 110) and the associated device 130_1 can be prepared for connectivity loss detection. Figure 1

[0056] In some example embodiments, the network device 110 can set a duty cycle for querying each terminal device 120. The devices 130 can employ the duty cycle to query the terminal devices 120 and report received power for the terminal devices 120 and / or information about lost terminal devices to the network device 110.

[0057] Figure 2 A high-level signaling diagram of a procedure 200 for connectivity loss detection is shown in accordance with some example embodiments of the present disclosure. For purposes of discussion, the procedure 200 will be described with reference to the environment 100. Figure 1 The procedure 200.

[0058] ​In process 200, network device 110 can send (205) a first configuration to set of devices 130_1, 130_2,..., 130_N, the first configuration including a first set of duty cycles for querying a plurality of associated terminal devices 120 (e.g., including terminal device 120_1). In this example, terminal device 120_1 is associated with both devices 130_1 and 130_2 as terminal device 120_1 is moving away from the coverage area 135_1 of device 130_1 towards device 130_2. In an example, the duty cycle for terminal device 120_1 can be set by network device 110 such that devices 130_1 and 130_2 associated with terminal device 120_1 can not query terminal device 120_1 at the same time.

[0059] As shown, devices 130_1 and 130_2 can receive (210, 215) the first configuration. Devices 130_1 and 130_2 can then query terminal device 120_1 using the duty cycle associated with terminal device 120_1. As an example, device 130_1 can send (220) a query to terminal device 120_1 using the first duty cycle configured by network device 110 for terminal device 120_1. After terminal device 120_1 receives (225) the query, terminal device 120_1 can backscatter (230) a signal to device 130_1 as a response to the query. Figure 2

[0060] In this document, a query performed by a device 130 can not be a specific command, but rather simply an interaction (unicast) that a device 130 can have with a single terminal device 130, including, for example, a normal interrogation process from a device 130 to retrieve specific data from a terminal device 120.

[0061] After device 130_1 receives (235) the signal from terminal device 120_1 as a response to the query, device 130_1 can determine (240) a measured power level of the signal. The measured power level can be obtained based on a received signal power, a signal to interference noise ratio (SINR), and / or other received signal strength indications. Based on the measured power level of the signal, device 130_1 can send (245) a measurement report for terminal device 120_1 to network device 110.

[0062] ​As the terminal device 120_1 moves towards the device 130_2, the device 130_1 can not receive a response from the terminal device 120_1 or the measured power level of the signal from the terminal device 120_1 can be low. In this case, the measurement report from the device 130_1 can report a loss of connection with the terminal device 120_1. Based on such a report, after receiving (250) the measurement report for the terminal device 120_1, the network device 110 can reconfigure the duty cycle for each device 130 or initiate a re-association procedure for the terminal device 120_1.

[0063] Reference will be made to Figures 3 to 5 Some example implementations at the network device 110 are discussed.

[0064] Figure 3 A flowchart of an example method 300 for connectivity detection is shown in accordance with some example embodiments of the present disclosure. The method 300 can be implemented at the network device 110. For the purpose of discussion, reference will be made to Figure 1 The method 300 is described from the perspective of the network device 110.

[0065] At block 310, the network device 110 sends a first configuration to the set of devices 130_1, 130_2, …, 130_N, the first configuration including a first set of duty cycles for querying a plurality of terminal devices 120 associated with the devices. In some example embodiments, the first configuration can be an original configuration for the duty cycles provided to the devices 130 during an association procedure. Each device 130 can be associated with a different set of terminal devices 120, while some of the terminal devices 120 can be associated with more than one device 130.

[0066] In some example embodiments, the first set of duty cycles can be configured to avoid sending more than one query to a terminal device 120 at a querying occasion. For example, the network device 110 can configure each device 120 with a specific duty cycle. Thus, time diversity can be achieved in querying the same terminal device 120, thereby avoiding query collisions and further improving the efficiency of connectivity detection.

[0067] In some example embodiments, the frequency for querying a terminal device 120 can be determined based on the proximity between the set of devices 130 and the terminal device 120. In an example, for a terminal device 120 associated with more than one device 130, the querying frequency of a device 130 can be configured based on the measured power level of the signal backscattered from the tag reported by the device 130, such as a SINR measurement. For example, the device 130 closest to the terminal device 120 can have the highest querying frequency, thereby further improving the querying efficiency.

[0068] The proximity between the set of devices 130 and the terminal device 120 can be determined based on the power levels of signals measured by the set of devices 130 for the terminal device 120. In an example, the proximity between a device 130 and the terminal device 120 can be identified during an association procedure of the terminal device 120 based on measurements of signal received power performed and reported by the device 130.

[0069] Reference will be made to the drawings to discuss examples of configuration for query frequency. Figure 4

[0070] Figure 4 An example configuration 400 for query frequency for a terminal device 120 is shown in accordance with some example embodiments of the present disclosure.

[0071] In this example, three devices 130 (referred to as a first device, a second device, and a third device, respectively) are associated with a single terminal device 120. The first device can have reported the highest SINR for signals backscattered from the terminal device 120, followed by the third device, and then the second device. Based on this, the first device is configured with a duty cycle #1 to query the terminal device 120 every 4 time units; the third device is configured with a duty cycle #3 to query the terminal device 120 every 8 time units; and the second device is configured with a duty cycle #2 to be restricted to one query every 30 time units.

[0072] In an example, as shown in Figure 4 , the first device can skip a query opportunity at time 7 to allow for a query by the second device, further avoiding a collision. The duty cycle #1 and the duty cycle #3 are orthogonal, so the first device need not skip an additional query occasion for the third device. Other methods for diversifying the query period are possible.

[0073] Still referring to Figure 3 , at block 320, the network device 110 receives a set of measurement reports from the set of devices 130_1, 130_2, …, 130_N for a plurality of terminal devices 120. The reports can be received periodically or triggered by an event, which can depend on the configuration of the network or the network device 110. In some example embodiments, a report in the set of measurement reports can include at least one identification (ID) of at least one terminal device in the plurality of terminal devices and at least one measured power level of a signal backscattered by the at least one terminal device.

[0074] ​The measurement report can include a report of a loss of connection with the terminal device 120. In some example embodiments, the network device 110 can configure a first condition for identifying a loss of connection with a terminal device of the plurality of terminal devices, and transmit a configuration including the first condition to the set of devices 130_1, 130_2,..., 130_N. The first condition can relate to any factor or parameter related to the connectivity or mobility state of the device 130 and the terminal device 120.

[0075] In an example, the first condition can be based on a comparison of a measured power level of a signal backscattered by the terminal device to a power level threshold. The power level threshold can be configured by the network device 110. For example, the network device 110 can transmit a configuration including a power level threshold for identifying a loss of connection with a terminal device of the plurality of terminal devices to the set of devices 130_1, 130_2,..., 130_N.

[0076] The power level threshold can include a minimum power or energy threshold to declare the terminal device 120 as lost. In an example, the minimum power threshold can indicate a minimum power that a received power of the backscattered signal needs to reach, or a minimum SINR of the backscattered signal.

[0077] Further, the first condition can take into account a first number of signals backscattered by the terminal device and a second number of queries to the terminal device. For example, the first condition can be satisfied when a measured power level of the first number of signals backscattered by the terminal device in response to the second number of queries to the terminal device is less than or equal to the power level threshold. As an example, the first condition can require detecting X number of queries out of Y number of attempted queries for which the measured power level of the signal backscattered by the terminal device is below a configured minimum threshold. X and Y represent positive integers. The values of X and Y can be configured as the first configuration in the association procedure.

[0078] In some example embodiments, the network device 110 can transmit a configuration including a set of power levels used for transmitting queries to the plurality of terminal devices to the set of devices 130_1, 130_2,..., 130_N. The configuration can be transmitted during the association procedure. The power levels can include a maximum allowed power level for transmissions towards the terminal devices.

[0079] In some example embodiments, the network device 110 can use the measurement results in the measurement report, including the measured power level or loss event, to fine-tune the power level threshold (e.g., a minimum configured power threshold) used to identify a loss of connection with a particular terminal device or the power level (e.g., a maximum transmission power) used for transmissions towards a particular terminal device.

[0080] In some example embodiments, based on the received measurement reports (periodic or event-based), the network device 110 can send, to a subset of the set of devices 130_1, 130_2, …, 130_N, a second configuration comprising a second set of duty cycles for querying the terminal device 120. Thus, the network device 110 can dynamically reconfigure the query duty cycles used by the individual devices 130. It will be appreciated that although the first and second configurations as described above and other configurations as described below are discussed separately, some or even all of these configurations can be integrated or contained in one configuration.

[0081] Upon receiving a report from a device 130 about the loss of connection with the terminal device 120, the network device 110 can determine whether at least one further device 130 of the set of devices 130_1, 130_2, 130_N is associated with the terminal device 120, e.g., whether the terminal device 120 has been configured with a connection to any other device 130. If so, the network device 110 can send, to the at least one further device, a third configuration comprising at least one duty cycle for querying the terminal device 120. The third configuration can be part of the second configuration. Thus, the reconfiguration of duty cycles can be more efficient and effective.

[0082] In some example embodiments, the reconfiguration of duty cycles can be triggered based on a second condition for enabling the reconfiguration. The setting of the second condition can take into account any factor or parameter to facilitate the reestablishment of the connection between the device 130 and the terminal device 120.

[0083] In an example, the second condition can be based on the frequency of the duty cycles, e.g., a comparison of the value of the frequency to a threshold value. For example, the second condition can be satisfied when the frequency of the first number of duty cycles used by the at least one further device to query the first number of terminal devices is equal to or lower than a threshold frequency. The threshold value can be set according to implementation. Given that the terminal device can benefit from more frequent query duty cycles, a relatively lower frequency of duty cycles can be suboptimal. The reconfiguration can be enabled if the query duty cycles configured for the at least one further device have a lower query frequency or a suboptimal frequency.

[0084] In the context of the present disclosure, a suboptimal query frequency refers to a query frequency that is not perfectly aligned with the ideal frequency of retrieving data from the terminal device. For example, upon the terminal device 120 having lost the connection with the device 130, its query frequency can be, e.g., once every 30 seconds from the remaining devices associated with the terminal device 120. If the data retrieval from the terminal device 120 requires data every 10 seconds during a certain time period, the network device 110 can identify this suboptimal configuration based on assistance information from some higher layer entity and perform the reconfiguration.

[0085] The determination of the suboptimal frequency can take into account the network load or other network status. For example, data retrieval at a frequency of 30 seconds can not be allowed during high load working hours in an industrial environment, but can be acceptable during low working hours. Thus, during low working hours, the network device 110 can wait until several reconfigurations are needed for a particular device 130 to reduce the control plane (c-plane) load in the network.

[0086] In addition to the frequency of the duty cycle, the second condition for enabling reconfiguration of the duty cycle can consider the number of terminal devices with suboptimal configuration for the duty cycle from the plurality of terminal devices associated with the particular device 130. For example, the second condition can require that the frequency of the first number of duty cycles used by the device 130 to query a first number of terminal devices of a second number of terminal devices associated with the device 130 is equal to or lower than a threshold frequency. In an example, the proportion of terminal devices of the associated terminal devices that have a suboptimal configuration can be equal to or greater than a threshold proportion. The threshold proportion can be set according to the implementation. For example, if the device 130 is configured with 10 terminal devices 120 and only one of the ten terminal devices 120 has a suboptimal query configuration, the network device 110 can decide not to reconfigure the device 130 to change the duty cycle for the terminal devices with a suboptimal configuration.

[0087] Alternatively or additionally, the second condition can consider the number of connection losses reported by the device(s) 130, for example, the number of connection losses reported by a single device, the number of devices, or a threshold number of devices. In an example, the second condition can be satisfied when the number of connection losses is equal to or greater than a threshold number. Thus, if the number of connection losses requiring reconfiguration is large, for example, above a threshold number of connection losses, the reconfiguration can be triggered.

[0088] In some cases, the devices 130 can be mobile and each device 130 can be configured with a different duty cycle for querying different tags. In these cases, if one device 130 reports a tag as lost, a reconfiguration for all terminal devices associated with that device can not be needed because other terminal devices are able to be queried, even if at a lower frequency. If the device prioritized for the terminal device remains declaring the terminal device lost, the duty cycle of the queries for the remaining readers can not be optimal, and thus a reconfiguration can be triggered. With such a second condition, a reconfiguration can be performed when the device(s) 130 include a plurality of terminal devices with suboptimal query periods, without needing to configure the device(s) 130 immediately after the device 130 reports a lost terminal device.

[0089] The use of the second condition for enabling reconfiguration of the duty cycle can further reduce the overhead for reconfiguration of the duty cycle when the connection of the terminal device 120 to one or more devices 130 is lost.

[0090] Alternatively or additionally, if the received measurement report includes a report on a loss of connection with the terminal device, the network device 110 can send a configuration for reconfiguring a power level threshold for identifying a loss of connection with the terminal device and / or a power level for transmitting an inquiry to the terminal device to the set of devices 130_1, 130_2, …, 130_N. Alternatively, the network device 110 can initiate a re-association procedure for the terminal device.

[0091] Some example operations of the network device 110 will be discussed below with reference to Figure 5

[0092] Figure 5 A flowchart of an example process 500 at the network device 110 according to some example embodiments of the present disclosure is shown. In this example, a gNB can act as the network device 110, a reader can act as a device 130, and a tag can act as a terminal device 120.

[0093] In the process 500, at 505, the network device 110 or gNB can configure a duty cycle with which a reader can inquire a particular tag, labeled Tag #1, a minimum power threshold, a transmission power, and a criterion for declaring a tag lost. For example, the gNB can configure a specific inquiry period for each reader. For tags associated with more than one reader, the inquiry frequency of the readers can be configured based on SINR measurements of signals backscattered from the tag reported by the readers.

[0094] The gNB can wait for a measurement report from a reader in which a tag has been declared “lost” or “missing”. Depending on the configuration provided by the gNB to the reader, the measurement report can be periodic and / or event-based. As Figure 5 shown, at 510, the gNB can determine whether the received measurement report indicates a lost connection between the reader and Tag #1. Upon receiving such a report, at 515, the gNB can determine whether other readers are associated with Tag #1. For example, the gNB can check whether the tag has been configured with a connection to any other reader.

[0095] ​If there are other readers associated with tag #1, at 520, the gNB can determine whether the duty cycle for enough tags needs to be reconfigured for any readers associated with tag #1. For example, the gNB can determine whether the duty cycle for a large number of tags needs to be reconfigured for the readers associated with tag #1 and other tags. If yes, at 525, the gNB can reconfigure the required readers. If no, the procedure 500 returns to 510, where the gNB can continue to monitor the measurement reports from the readers indicating the lost connection with the tags.

[0096] If it is determined at 515 that there are no other readers associated with the tag or associated with a SINR measurement above the threshold, at 530, the gNB can evaluate whether a transmission power or minimum power threshold reconfiguration for the readers associated with tag #1 can help establish a connection with tag #1, e.g., by reconfiguring the minimum power threshold and / or transmission power set for the reader-tag pair, the connectivity between the tag and the reader can be reestablished.

[0097] If yes, the procedure 500 can proceed to 525, where the gNB can reconfigure the required readers. For example, if the minimum power threshold to declare a lost tag or the maximum transmission power from the reader to the tag is set very conservatively, this can be modified at this stage. Thus, if the received power or SINR reported for the tag from all readers is below the threshold, the gNB can attempt to reconfigure the readers with a lower minimum received power or SINR threshold and / or a higher transmission power.

[0098] If such a reconfiguration does not help, at 535, the gNB can trigger a re-association procedure. Otherwise, the procedure 500 can proceed to 525, where the gNB can reconfigure the required readers. For example, if there is no possibility to reestablish the connectivity between the tag and the known readers, the gNB can fallback to initiate a re-association procedure.

[0099] By allowing multiple readers to report the SINR for a particular tag, a particular tag can be actively re-associated with a different reader without losing connectivity, which can enable tag and / or reader mobility. Moreover, the re-association procedure has low complexity to allow robust communication for backscatter devices such as tags in environments where the tags and / or readers can move. Compared to traditional re-association procedures, the proposed re-association procedure can enable tag and / or reader mobility with lower overhead.

[0100] In some example embodiments, the network device 110 can send a configuration to the set of devices 130_1, 130_2, …, 130_N to enable querying of the plurality of terminal devices 120. Based on such a configuration, the devices 130 can trigger the querying of the terminal devices 120.

[0101] Example implementations at the devices 130 will be discussed below with reference to Figure 6 and Figure 7 FIG. 2.

[0102] Figure 6 A flowchart of an example method 600 for connectivity detection at the devices 130 is shown in accordance with some example embodiments of the present disclosure. For purposes of discussion, the method 600 will be described from the perspective of a device 130. Figure 1 The method 600 will be described from the perspective of a device 130.

[0103] At block 610, the device 130 receives a first configuration from the network device 110 including a first duty cycle for querying the terminal devices 120. At block 620, the device 130 sends a query to the terminal devices 120 using the first duty cycle. As described above, the network device 110 can configure the device 130 to enable such querying. Based on the configuration, the device 130 can initiate querying for its associated terminal devices.

[0104] At block 630, the device 130 determines a measured power level of a signal backscattered by the terminal devices 120 in response to the query. For example, each time the device 130 queries the terminal devices 120, the device 130 can measure the signal backscattered by the terminal devices 120. At block 640, based on the measured power level of the backscattered signal, the device 130 sends a measurement report to the network device 110 for the terminal devices 120.

[0105] The measurement report can be sent periodically or triggered by an event, which can depend on the configuration provided by the network device 110 to the device. In some example embodiments, the measurement report can include an identification (ID) of the terminal devices and the measured power level of the signal backscattered by the terminal devices.

[0106] In some example embodiments, the device 130 can identify or assess whether a terminal device 120 is lost. If it is determined that a terminal device 120 is lost, the device 130 can send a report to the network device 110 regarding the loss of connection with the terminal device 120.

[0107] In some example embodiments, the device 130 can receive a configuration from the network device 110 including a first condition for identifying a loss of connection with a terminal device. Based on the first condition, the device 130 can determine a lost terminal device. Alternatively or additionally, a preconfigured or default criterion can be used by the device 130 to declare a lost terminal device.

[0108] In an example, the first condition can be based on a measured power level for the terminal device. For example, the first configuration can be satisfied when a measured power level of the first number of signals backscattered by the terminal device in response to the second number of queries to the terminal device is less than or equal to a power level threshold.

[0109] In some example embodiments, the device 130 can receive from the network device 110 a configuration including a threshold power level for identifying a loss of connection with the terminal device. In some example embodiments, the device 130 can receive from the network device 110 a configuration including a power level for transmitting queries to the terminal device 120. Accordingly, the device 130 can send queries to the terminal device 120 at the configured power level.

[0110] If the device 130 determines that the connection with the terminal device 120 is lost, the device 130 can send a report to the network device 110 about the loss of connection with the terminal device 120. The report can also include the ID of the terminal device 120 and its latest measurements of signals backscattered by the terminal device 120. In some example embodiments, the device 130 can discard the configuration related to querying the terminal device 120, e.g., the first configuration including the first duty cycle of queries to the terminal device. In some example embodiments, the device 130 can stop querying the terminal device 120 and no longer query the terminal device 120. In this way, the device 130 can automatically discard the queries to the terminal device without the need for c-plane procedures.

[0111] Figure 7 A flowchart illustrating an example process 700 at the device 130 in accordance with some example embodiments of the present disclosure is shown. In this example, a gNB can act as the network device 110, a reader can act as the device 130, and a tag can act as the terminal device 120.

[0112] In the process 700, at 705, the device 130 or reader can receive a duty cycle to query a tag labeled Tag #1, a minimum power threshold, a transmission power, and a criterion for declaring a tag loss. For example, the reader can be configured with a particular duty cycle that can be employed to query Tag #1. In addition, the reader can be provided with a minimum power threshold and a criterion for declaring a tag loss as well as a maximum allowed power level for transmissions towards the tag.

[0113] At 710, the reader can query tag #1 and measure the received power or SINR of the backscattered signal by tag #1. The reader can initiate a query for its associated tag according to the configuration provided at 705. At 715, the reader can determine whether the measured power of the backscattered signal is below a preconfigured threshold or whether tag #1 is lost. For example, each time the reader queries tag #1, the backscattered signal can be measured and the tag can be evaluated for loss.

[0114] If the measured power of the backscattered signal is below a preconfigured threshold or tag #1 is lost, at 720, the reader can stop querying tag #1 and discard the duty cycle configured for tag #1. In an example, if the reader declares a tag lost according to the configured criteria, the first configuration including the first duty cycle of queries for the end device can be discarded.

[0115] At 725, the reader can send a measurement report to the serving cell of the gNB. The report can include the received power or SINR and / or information about a lost or missing tag. In an example, if the reader declares a tag lost, a measurement report indicating the tag loss can be sent to the gNB, which can include the tag ID and its latest measurements of the signal backscattered by the tag. These measurements can be used by the gNB, for example, to fine-tune the minimum configured power threshold or maximum transmission power of the reader for a particular tag.

[0116] If at 715 it is determined that the measured power of the backscattered signal is above a preconfigured threshold, at 730, the reader can wait for the next query period in which a query needs to be performed for tag #1. Then, the process 700 proceeds to 710, where the reader repeats querying tag #1 and measuring the received power or SINR of the signal backscattered by tag #1.

[0117] All operations and features related to the device 130 described above with reference to Figures 1 to 5 apply equally to the method 600 and the process 700 with similar effects. For the purpose of simplicity, details will be omitted.

[0118] Figure 8 A signaling diagram of a process 800 for connectivity detection and re-association is shown in accordance with some example embodiments of the present disclosure. For the purpose of discussion, reference will be made to Figure 1 the device 130 described above.

[0119] In this example, tag 802, labeled Tag 1, may serve as terminal device 120, readers or stimulators 804 and 806, labeled Reader / stimulator 1 and Reader / stimulator 2, respectively, may serve as device 130, and reader or stimulator 804 may be associated with or connected to tag 802. gNB 808 may serve as network device 110.

[0120] like Figure 8 As shown, at 810, tag-reader association can be performed using any suitable association process. At 812, the reader can be preconfigured with a duty cycle that can be used to query a specific tag, and the gNB 808 can determine the reader-tag duty cycle based on the tag's measurements reported by the reader. At 814, the reader or stimulator 804 can illuminate a signal toward the tag 802. At 816, the tag 802 can backscatter a signal toward the reader or stimulator 804 in response. At 818, the reader or stimulator 804 can measure the backscattered signal. At 820, the reader or stimulator 804 can send periodic measurement reports to the gNB 808 that include the tag ID and the tag's received power level or the reader's RSRP.

[0121] In this example, reader 1 provides a measurement report to gNB 808 stating that tag 1 is lost. This may cause gNB 808 to reconfigure reader 2's query period for tag 1 at 822. Figure 8 As shown, at 824, gNB 808 may initiate reconfiguration of the tag-reader duty cycle for a subset of readers associated with tag 802. At 826, if all readers associated with the tag are reporting low power, gNB 808 may trigger reassociation for readers not previously associated with tag 802.

[0122] For example, if the reconfiguration of the query period does not help improve the tag's SINR quality above a threshold, e.g., no other reader reports a measured SINR above the threshold for tag 802, the gNB may use the reported measurement of the backscatter signal to fine-tune the minimum configured power threshold for the specific tag(s) or to start a new association procedure.

[0123] In some example embodiments, an apparatus capable of performing any of the methods 300 (e.g., Figure 1 The network device 110 in the embodiment may include a component for performing the corresponding operations of the method 300. The component may be implemented in any suitable form. For example, the component may be implemented in a circuit or a software module. The apparatus may be implemented as or included in Figure 1 In the network device 110.

[0124] In some example embodiments, the apparatus comprises means for transmitting, to a set of devices, a first configuration comprising a first set of duty cycles for querying a plurality of terminal devices associated with the set of devices; and means for receiving, from the set of devices, a set of measurement reports for the plurality of terminal devices.

[0125] In some example embodiments, the apparatus comprises means for transmitting, to a subset of the set of devices, a second configuration comprising a second set of duty cycles for querying a terminal device.

[0126] In some example embodiments, the apparatus comprises means for transmitting, to the set of devices, a configuration comprising a power level threshold to be used to identify a loss of connection with a terminal device of the plurality of terminal devices.

[0127] In some example embodiments, the apparatus comprises means for transmitting, to the set of devices, a configuration comprising a set of power levels to be used to transmit queries to the plurality of terminal devices.

[0128] In some example embodiments, the apparatus comprises means for transmitting, to the set of devices, a configuration comprising a first condition to be used to identify a loss of connection with a terminal device of the plurality of terminal devices.

[0129] In some example embodiments, the first condition is satisfied when a measured power level of a first number of signals backscattered by the terminal device in response to a second number of queries to the terminal device is less than or equal to a power level threshold.

[0130] In some example embodiments, the set of measurement reports comprises a report on a loss of connection with a terminal device of the plurality of terminal devices.

[0131] In some example embodiments, the apparatus comprises means for determining, in response to receiving a report on a loss of connection with a terminal device from a device of the set of devices, that at least one further device of the set of devices is associated with the terminal device; and means for transmitting, to the at least one further device, a third configuration comprising at least one duty cycle for querying the terminal device based on a second condition for enabling reconfiguration of duty cycles.

[0132] In some example embodiments, the second condition is satisfied when a frequency of duty cycles used by the at least one further device to query a first number of terminal devices of a second number of terminal devices associated with the at least one further device is equal to or below a threshold frequency.

[0133] In some example embodiments, the second condition is satisfied when a number of connection losses reported is equal to or greater than a threshold number.

[0134] In some example embodiments, the apparatus comprises, in response to the set of measurement reports including a report about a loss of connection with a terminal device of the plurality of terminal devices: means for sending, to the set of devices, a configuration for reconfiguring one or more of a power level threshold to be used to identify the loss of connection with the terminal device and a power level to be used for transmitting a query to the terminal device; or means for initiating a re-association procedure for the terminal device.

[0135] In some example embodiments, the first set of duty cycles is configured to avoid more than one query being transmitted to a terminal device of the plurality of terminal devices at a query occasion.

[0136] In some example embodiments, the frequency for querying the terminal device of the plurality of terminal devices is determined based on a proximity between the set of devices and the terminal device.

[0137] In some example embodiments, the apparatus comprises means for determining the proximity between the set of devices and the terminal device based on power levels of signals measured by the set of devices for the terminal device.

[0138] In some example embodiments, the measurement reports in the set of measurement reports include at least one identification of at least one terminal device of the plurality of terminal devices and at least one measured power level of a signal backscattered by the at least one terminal device.

[0139] In some example embodiments, the measurement reports in the set of measurement reports are received periodically by the network device or triggered by an event.

[0140] In some example embodiments, the apparatus comprises means for sending, to the set of devices, a configuration for enabling querying of the plurality of terminal devices.

[0141] In some example embodiments, the apparatus further comprises means for performing other operations in the method 300 or other operations in some example embodiments of the network device 110. In some example embodiments, the means comprise: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to perform.

[0142] In some example embodiments, an apparatus (e.g., the device 130 in Figure 1 ) capable of performing any of the method 600 can comprise means for performing the respective operations of the method 600. The means can be implemented in any suitable form. For example, the means can be implemented in circuitry or software modules. The apparatus can be implemented as or included in the device 130 in Figure 1 .

[0143] In some example embodiments, the apparatus includes means for receiving, from a network device, a first configuration including a first duty cycle for querying a terminal device; means for sending a query to the terminal device using the first duty cycle; means for determining a measured power level of a signal backscattered by the terminal device in response to the query; and means for sending a measurement report for the terminal device to the network device based on the measured power level of the backscattered signal.

[0144] In some example embodiments, the apparatus comprises means for receiving, from a network device, a configuration comprising a threshold power level to be used to identify a loss of connection with a terminal device.

[0145] In some example embodiments, the apparatus comprises means for receiving, from the network device, a configuration comprising a power level to be used for transmitting the query to the terminal device, wherein the query is sent to the terminal device based on the configuration.

[0146] In some example embodiments, the apparatus comprises means for receiving, from the network device, a configuration comprising a first condition used to identify a loss of connection with the terminal device.

[0147] In some example embodiments, the first condition is satisfied when a measured power level of a first number of signals backscattered by the terminal device in response to a second number of queries by the terminal device is less than or equal to a power level threshold.

[0148] In some example embodiments, the measurement report comprises an identification of the terminal device and a measured power level of a signal backscattered by the terminal device.

[0149] In some example embodiments, measurement reports are sent periodically or triggered by an event.

[0150] In some example embodiments, the apparatus comprises means for receiving a configuration from a network device for enabling querying of the terminal device, wherein the query is sent based on the configuration.

[0151] In some example embodiments, the apparatus comprises means for sending a report regarding the loss of connection with the terminal device to the network device based on determining the loss of connection with the terminal device.

[0152] In some example embodiments, the apparatus comprises means for discarding a first configuration of a first duty cycle comprising a query for the terminal device.

[0153] In some example embodiments, the apparatus comprises means for stopping querying the terminal device.

[0154] In some example embodiments, the apparatus also includes means for performing other operations in method 600 or other operations in some example embodiments of device 130. In some example embodiments, the apparatus includes at least one processor; and at least one memory that stores instructions that, when executed by the at least one processor, cause the apparatus to perform.

[0155] Figure 9 is a simplified block diagram of a device 900 suitable for implementing example embodiments of the present disclosure. The device 900 can be provided to implement a communication device, for example, Figure 1 The network device 110 or device 130 shown. As shown, the device 900 includes one or more processors 910, one or more memories 920 coupled to the processors 910, and one or more communication modules 940 coupled to the processors 910.

[0156] The communication module 940 is for bidirectional communication. The communication module 940 has one or more communication interfaces to facilitate communication with one or more other modules or devices. The communication interface can represent any interface necessary to communicate with other network elements. In some example embodiments, the communication module 940 can include at least one antenna.

[0157] The processor 910 can be of any type suitable to the local technical network, and can include one or more of central processing units (CPUs), graphics processing units (GPUs), application-specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), digital signal processors (DSPs), and processors based on multi-core processor architectures, as non-limiting examples. The device 900 can have multiple processors such as a dedicated integrated circuit chip that is time-slaved to a clock that is synchronized with a master processor.

[0158] The memory 920 can include one or more non-transitory memories and one or more transitory memories. Examples of non-transitory memories include, but are not limited to, read-only memories (ROMs) 924, electrically programmable read-only memories (EPROMs), flash memories, hard disks, compact disks (CDs), digital video disks (DVDs), optical disks, laser disks, and other magnetic and / or optical storage. Examples of transitory memories include, but are not limited to, random access memories (RAMs) 922 and other volatile memories that will not maintain their state over a power cycle.

[0159] The computer program 930 includes computer-executable instructions that are executed by the associated processor 910. The instructions of the program 930 can include instructions for performing the operations / actions of some example embodiments of the present disclosure. The program 930 can be stored in a memory, such as the ROM 924. The processor 910 can perform any suitable actions and processes by loading a program 930 into the RAM 922.

[0160] The exemplary embodiments of the present disclosure may be implemented with the aid of a program 930 so that the device 900 can perform the operations described in the reference Figures 1 to 8 Any process of the present disclosure discussed. The example embodiments of the present disclosure may also be implemented by hardware or by a combination of software and hardware.

[0161] In some example embodiments, the program 930 may be tangibly embodied in a computer-readable medium that may be included in the device 900 (such as in the memory 920) or in another storage device accessible to the device 900. The device 900 may load the program 930 from the computer-readable medium into the RAM 922 for execution. In some example embodiments, the computer-readable medium may include any type of non-transitory storage medium, such as a ROM, EPROM, flash memory, hard disk, CD, DVD, etc. The term "non-transitory" as used herein is a limitation on the medium itself (i.e., tangible, not a signal), not on the persistence of data storage (e.g., RAM versus ROM).

[0162] Figure 10 An example of a computer readable medium 1000 is shown, which may be in the form of a CD, DVD, or other optical storage disc. The computer readable medium 1000 stores a program 930 thereon.

[0163] In general, various embodiments of the present disclosure may be implemented in hardware or dedicated circuits, software, logic, or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software executed by a controller, microprocessor, or other computing device. Although various aspects of the embodiments of the present disclosure are illustrated and described as block diagrams, flow charts, or using some other graphical representations, it should be understood that the blocks, devices, systems, techniques, or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, dedicated circuits or logic, general-purpose hardware or a controller or other computing device, or some combination thereof.

[0164] Some example embodiments of the present disclosure also provide at least one computer program product tangibly stored on a computer-readable medium (such as a non-transitory computer-readable medium). The computer program product includes computer-executable instructions, such as those included in a program module, which are executed in a device on a target physical or virtual processor to perform any method as described above. Typically, a program module includes routines, programs, libraries, objects, classes, components, data structures, etc. that perform specific tasks or implement specific abstract data types. In various embodiments, the functions of the program modules can be combined or split between program modules as needed. Machine executable instructions for program modules can be executed in local or distributed devices. In distributed devices, program modules can be located in both local and remote storage media.

[0165] The program code for implementing the method of the present disclosure can be written in any combination of one or more programming languages. The program code can be provided to a processor or controller of a general-purpose computer, a special-purpose computer, or other programmable data processing device so that when the program code is executed by the processor or controller, the functions / operations specified in the flow chart and / or block diagram are implemented. The program code can be executed entirely on the machine, partially on the machine, as a stand-alone software package, partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0166] In the context of the present disclosure, computer program codes or related data may be carried by any suitable carrier to enable a device, apparatus, or processor to perform the various processes and operations described above. Examples of carriers include signals, computer-readable media, and the like.

[0167] The computer readable medium may be a computer readable signal medium or a computer readable storage medium. The computer readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of computer readable storage media would include an electrical connection having one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0168] In addition, although operations are depicted in a particular order, it should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all operations shown be performed to achieve the desired result. In some cases, multitasking and parallel processing can be advantageous. Similarly, although several specific implementation details are included in the above discussion, these should not be interpreted as limitations on the scope of this disclosure, but rather as descriptions of features that can be specific to a particular embodiment. Unless expressly stated otherwise, certain features described in the context of a separate embodiment may also be implemented in combination in a single embodiment. On the contrary, unless expressly stated otherwise, the various features described in the context of a single embodiment may also be implemented in multiple embodiments individually or in any suitable subcombination.

[0169] Although the disclosure has been described in language specific to structural features and / or methodological acts, it should be understood that the disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

1. A network device comprising: at least one processor; as well as at least one memory storing instructions, wherein when the instructions are executed by the at least one processor, the network device causes the network device to at least perform: Sending a first configuration to a device set, the first configuration comprising a first duty cycle set for querying a plurality of terminal devices associated with the device set; and A set of measurement reports for the plurality of terminal devices is received from the set of devices.

2. The network device of claim 1 , wherein the at least one memory and the at least one processor further cause the network device to execute: A second configuration is sent to a subset of the set of devices, the second configuration including a second set of duty cycles for querying the terminal device.

3. The network device according to any one of claims 1 to 2, wherein the at least one memory and the at least one processor further cause the network device to execute: A configuration is sent to the set of devices including a power level threshold to be used to identify a loss of connection with a terminal device in the plurality of terminal devices.

4. The network device according to any one of claims 1 to 3, wherein the at least one memory and the at least one processor further cause the network device to execute: A configuration including a set of power levels is sent to the set of devices, the set of power levels to be used for transmitting queries to the plurality of terminal devices.

5. The network device according to any one of claims 1 to 4, wherein the at least one memory and the at least one processor further cause the network device to execute: A configuration including a first condition is sent to the set of devices, the first condition to be used to identify a loss of connection with a terminal device of the plurality of terminal devices.

6. The network device of claim 5, wherein the first condition is met when a measured power level of a first number of signals backscattered by the terminal device in response to a second number of queries from the terminal device is less than or equal to a power level threshold.

7. The network device according to any one of claims 1 to 6, wherein the set of measurement reports comprises a report on a loss of connection with a terminal device of the plurality of terminal devices.

8. The network device of claim 7, wherein the at least one memory and the at least one processor cause the network device to execute: In response to receiving the report of loss of connection with the terminal device from a device in the set of devices, determining that at least one further device in the set of devices is associated with the terminal device; and Based on a second condition for enabling reconfiguration of the duty cycle, a third configuration is sent to the at least one further device, the third configuration comprising at least one duty cycle for querying the terminal device.

9. A network device according to claim 8, wherein the second condition is met when the frequency of the duty cycle of the first number of terminal devices among the second number of terminal devices associated with the at least one other device is equal to or less than a threshold frequency.

10. The network device of claim 8, wherein the second condition is satisfied when the number of reported connection losses is equal to or greater than a threshold number.

11. The network device according to any one of claims 1 to 10, wherein the at least one memory and the at least one processor further cause the network device to execute: In response to the measurement report set including a report on a loss of connection with a terminal device of the plurality of terminal devices: sending a configuration to the set of devices to reconfigure one or more of a power level threshold to be used to identify a loss of connection with the terminal device and a power level to be used to transmit a query to the terminal device; or Initiate a re-association process for the terminal device.

12. The network device according to any one of claims 1 to 11, wherein the first set of duty cycles is configured to avoid more than one query being sent to a terminal device of the plurality of terminal devices at a query opportunity. 13 . The network device according to claim 1 , wherein a frequency for querying a terminal device of the plurality of terminal devices is determined based on a proximity between the set of devices and the terminal device.

14. The network device of claim 13, wherein the at least one memory and the at least one processor further cause the network device to execute: The proximity between the set of devices and the terminal device is determined based on a power level of a signal measured by the set of devices for the terminal device.

15. The network device according to any one of claims 1 to 14, wherein the measurement reports in the measurement report set include at least one identification of at least one terminal device among the multiple terminal devices and at least one measured power level of a signal backscattered by the at least one terminal device. 16 . The network device according to claim 1 , wherein the measurement reports in the measurement report set are received by the network device periodically or triggered by an event.

17. The network device according to any one of claims 1 to 16, wherein the at least one memory and the at least one processor further cause the network device to execute: A configuration for enabling querying of the plurality of terminal devices is sent to the set of devices.

18. A device comprising: at least one processor; as well as at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to at least: receiving a first configuration from a network device, the first configuration comprising a first duty cycle for querying a terminal device; sending a query to the terminal device using the first duty cycle; determining a measured power level of a signal backscattered by the terminal device in response to the query; as well as Based on the measured power level of the backscattered signal, a measurement report for the terminal device is sent to the network device.

19. The apparatus of claim 17, wherein the at least one memory and the at least one processor further cause the apparatus to perform: A configuration is received from the network device including a threshold power level used to identify a loss of connection with the terminal device.

20. The apparatus of any one of claims 18 to 19, wherein the at least one memory and the at least one processor further cause the apparatus to perform: receiving a configuration from the network device including a power level to be used for transmitting a query to the terminal device, The query is sent to the terminal device based on the configuration.

21. The apparatus of any one of claims 18 to 20, wherein the at least one memory and the at least one processor further cause the apparatus to perform: A configuration including a first condition is received from the network device, the first condition being used to identify a loss of connection with the terminal device.

22. The device of claim 21, wherein the first condition is met when a measured power level of a first number of signals backscattered by the terminal device in response to a second number of queries by the terminal device is less than or equal to a power level threshold.

23. The apparatus of any one of claims 18 to 22, wherein the measurement report comprises an identification of the terminal device and a measured power level of a signal backscattered by the terminal device.

24. The apparatus according to any one of claims 18 to 23, wherein the measurement report is sent periodically or triggered by an event.

25. The apparatus of any one of claims 18 to 24, wherein the at least one memory and the at least one processor further cause the apparatus to perform: receiving a configuration from the network device for enabling querying of the terminal device, Wherein the query is sent based on the configuration.

26. The apparatus of any one of claims 18 to 25, wherein the at least one memory and the at least one processor cause the apparatus to perform: Based on determining the loss of connection with the terminal device, a report regarding the loss of connection with the terminal device is sent to the network device.

27. The apparatus of claim 26, wherein the at least one memory and the at least one processor further cause the apparatus to perform: The first configuration including the first duty cycle for the query of the terminal device is discarded.

28. The apparatus of any one of claims 26 to 27, wherein the at least one memory and the at least one processor further cause the apparatus to perform: Stop querying the terminal device.

29. A method comprising: Sending a first configuration to a device set, the first configuration comprising a first duty cycle set for querying a plurality of terminal devices associated with the device set; as well as A set of measurement reports for the plurality of terminal devices is received from the set of devices.

30. A method comprising: receiving a first configuration from a network device, the first configuration comprising a first duty cycle for querying a terminal device; sending a query to the terminal device using the first duty cycle; determining a measured power level of a signal backscattered by the terminal device in response to the query; as well as Based on the measured power level of the backscattered signal, a measurement report for the terminal device is sent to the network device.

31. An apparatus comprising: means for sending a first configuration to a set of devices, the first configuration comprising a first set of duty cycles for querying a plurality of terminal devices associated with the set of devices; as well as Means for receiving, from the set of devices, a set of measurement reports for the plurality of terminal devices.

32. An apparatus comprising: means for receiving a first configuration from a network device, the first configuration comprising a first duty cycle for querying a terminal device; means for sending a query to the terminal device using the first duty cycle; means for determining a measured power level of a signal backscattered by said terminal device in response to said query; as well as means for sending a measurement report for the terminal device to the network device based on the measured power level of the backscattered signal.

33. A computer-readable medium comprising instructions stored thereon, the instructions being configured to cause an apparatus to at least perform the method according to any one of claims 29 to 30.

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