CN116325948A

CN116325948A - Cell selection in non-terrestrial networks

Info

Publication number: CN116325948A
Application number: CN202080106366.0A
Authority: CN
Inventors: 温萍萍; 袁平; 王文剑
Original assignee: Nokia Shanghai Bell Co Ltd; Nokia Solutions and Networks Oy
Current assignee: Nokia Shanghai Bell Co Ltd; Nokia Solutions and Networks Oy
Priority date: 2020-10-19
Filing date: 2020-10-19
Publication date: 2023-06-23
Also published as: WO2022082376A1

Abstract

Embodiments of the present disclosure relate to cell selection in non-terrestrial networks. A method, comprising: receiving, at a first device, a first message from a second device managing a source cell of the first device, the first message including at least cell selection information for supporting discontinuous reception or extended discontinuous reception at the first device; and selecting a target cell for the first device based on the cell selection information, without making measurements of the source cell after waking up from a corresponding discontinuous reception or extended discontinuous reception period during the paging transmission window, the target cell being managed by a third device different from the second device. In this way, a fast and efficient cell selection procedure for terminal devices in RRC idle mode can be implemented in the NTN.

Description

Cell selection in non-terrestrial networks

Technical Field

Embodiments of the present disclosure relate generally to the field of telecommunications and, more particularly, relate to methods, apparatuses, devices, and computer-readable storage media for cell selection in non-terrestrial networks (NTNs).

Background

Narrowband internet of things (NB-IoT) technology is intended to support the long battery life of terminal devices in a communication network. Many schemes are designed for power saving purposes in NB-IoT, including Power Save Mode (PSM), discontinuous Reception (DRX), and extended DRX (eDRX). In particular, eDRX schemes are used by terminal devices in Radio Resource Control (RRC) idle state, the periods of which include deep sleep periods (i.e., eDRX periods) and Paging Transmission Windows (PTWs). Thus, a terminal device operating in the eDRX scheme periodically enters a deep sleep state and wakes up during the PTW. eDRX cycles may range from a minimum of 10.24 seconds to a maximum of 10485.76 seconds. After waking up from such a long sleep period, the terminal device typically performs cell measurement activities, which may then trigger a cell selection or reselection procedure.

In conventional communication networks utilizing NB-IoT technology, the terminal devices are typically fixed and have low mobility, so the cell selection criteria S and the cell reselection criteria R are applicable to those communication systems. NB-IoT technology has now been employed in NTNs to provide internet of things operation in remote areas with no or low cellular connectivity for a variety of industries such as transportation and logistics, solar, oil and gas extraction, utilities, agriculture, environmental monitoring, mining, and the like. The coverage of the NTN is provided by one or more non-terrestrial network devices that move at high speed relative to a fixed location on the earth, such as Low Earth Orbit (LEO) satellites, high Altitude Platforms (HAPS), unmanned Aerospace Surveillance (UAS) platforms, and the like. Taking NTN deployed with LEO satellite constellation as an example, when a terminal device wakes up from one eDRX cycle, multiple LEO satellites may have crossed the terminal device. This typically results in frequent and unavoidable Handover (HO) and cell reselection procedures involving fixed and mobile terminal devices, and may result in complex implementation or undesirable overhead.

Disclosure of Invention

In general, example embodiments of the present disclosure provide solutions for cell selection in NTN.

In a first aspect, a first device is provided. The first device includes at least one processor; at least one memory including computer program code; the at least one memory and the computer program code are configured to, with the at least one processor, cause the first device to: receiving a first message from a second device, the second device managing a source cell of the first device, the first message including at least cell selection information for supporting discontinuous reception or extended discontinuous reception at the first device; and selecting a target cell for the first device based on the cell selection information, without measuring the source cell after waking up from a corresponding discontinuous reception period or an extended discontinuous reception period during the paging transmission window, the target cell being managed by a third device different from the second device.

In a second aspect, a second device is provided. The second device includes at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the second device to: determining cell selection information for supporting discontinuous reception or extended discontinuous reception at a first device, a source cell of the first device being managed by a second device; and transmitting a first message including at least cell selection information for causing the first device to: the target cell for the first device is selected and during the paging transmission window, after waking up from a corresponding discontinuous reception or extended discontinuous reception period, no measurements are made of the source cell, the target cell being managed by a third device different from the second device.

In a third aspect, a method is provided. The method comprises the following steps: receiving, at the first device, a first message from a second device, the second device managing a source cell of the first device, the first message including at least cell selection information for supporting discontinuous reception or extending discontinuous reception at the first device; and selecting a target cell for the first device based on the cell selection information, without measuring the source cell after waking up from a corresponding discontinuous reception or extended discontinuous reception period during the paging transmission window, the target cell being managed by a third device different from the second device.

In a fourth aspect, a method is provided. The method comprises the following steps: determining, at the second device, cell selection information for supporting discontinuous reception or extended discontinuous reception at the first device, a source cell of the first device being managed by the second device; and transmitting a first message including at least cell selection information for causing the first device to: the target cell for the first device is selected and during the paging transmission window, after waking up from a corresponding discontinuous reception or extended discontinuous reception period, no measurements are made of the source cell, the target cell being managed by a third device different from the second device.

In a fifth aspect, a first apparatus is provided. The first device comprises: means for receiving, at the first device, a first message from a second apparatus, the second apparatus managing a source cell of the first device, the first message including at least cell selection information for supporting discontinuous reception or extended discontinuous reception at the first device; and means for selecting a target cell for the first device based on the cell selection information, and during the paging transmission window, after waking up from a corresponding discontinuous reception or extended discontinuous reception period, without making measurements on the source cell, the target cell being managed by a third device different from the second device.

In a sixth aspect, a second apparatus is provided. The second device includes: means for determining, at the second device, cell selection information for supporting discontinuous reception or extended discontinuous reception at the first device, a source cell of the first device being managed by the second device; and means for sending a first message comprising at least cell selection information to the first apparatus, the cell selection information being for causing the first device to: the target cell for the first device is selected and during the paging transmission window, after waking up from a corresponding discontinuous reception or extended discontinuous reception period, no measurements are made on the source cell, the target cell being managed by a third device different from the second device.

In a seventh aspect, there is provided a non-transitory computer readable medium comprising program instructions for causing an apparatus to perform at least a method according to the third aspect above.

In an eighth aspect, there is provided a non-transitory computer readable medium comprising program instructions for causing an apparatus to perform at least the method according to the fourth aspect described above.

It should be understood that the summary is not intended to identify key or essential features of the embodiments of the disclosure, nor is it intended to be used to limit the scope of the disclosure. Other features of the present disclosure will become apparent from the following description.

Drawings

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

FIG. 1A illustrates an example communication environment at time instant T1 in which embodiments of the present disclosure may be implemented;

FIG. 1B illustrates an example communication environment at a time instant T2 after a first time instant T1, according to some example embodiments of the present disclosure;

fig. 2 illustrates a schematic diagram of an example eDRX scheme, according to some example embodiments of the present disclosure;

fig. 3 illustrates a signaling flow for a cell selection procedure according to some example embodiments of the present disclosure;

Fig. 4 illustrates a flowchart of a method for cell selection according to some example embodiments of the present disclosure;

fig. 5 illustrates a flowchart of a cell selection method according to some example embodiments of the present disclosure;

FIG. 6 illustrates a simplified block diagram of an apparatus suitable for implementing embodiments of the present disclosure; and

fig. 7 illustrates a block diagram of an example computer-readable medium, according to some embodiments of the disclosure.

The same or similar reference numbers will be used throughout the drawings to refer to the same or like elements.

Detailed Description

Principles of the present disclosure will now be described with reference to some example embodiments. It should be understood that the description of these implementations is for illustrative purposes only and to assist those skilled in the art in understanding and practicing the present disclosure without implying any limitation on the scope of the present disclosure. The disclosure described herein may be implemented in various ways other than those described below.

In the following description and claims, unless defined otherwise, 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.

References in the present disclosure to "one embodiment," "an example embodiment," etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may 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 embodiment, it is submitted that it is within the knowledge of one skilled in the art to effect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

It will be understood that, although the terms "first" and "second," etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. 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 example embodiments. As used herein, the term "and/or" includes any and all combinations of one or more of the listed terms.

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," "has," "including," "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 groups thereof.

As used in this application, the term "circuitry" may refer to one or more or all of the following:

(a) Pure hardware circuit implementations (such as implementations using only analog and/or digital circuitry), and

(b) A combination of hardware circuitry and software, such as (as applicable):

(i) Combination of analog and/or digital hardware circuit(s) and software/firmware, and

(ii) Any portion of the hardware processor(s) having software, including digital signal processor(s), software, and memory(s), that work together to cause a device, 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)

The operation is performed, but the software may not exist when the operation is not required.

The definition of circuitry is applicable to all uses of that term in this application, including in any claims. As another example, as used in this application, the term circuitry also encompasses hardware-only circuitry or a processor (or multiple processors) or an implementation of a hardware circuit or portion of a processor and its accompanying software and/or firmware. For example, if applicable to the particular claim elements, the term circuitry also encompasses a baseband integrated circuit or processor integrated circuit for a mobile device, or a similar integrated circuit in a server, a cellular network device, or other computing or network device.

As used herein, the term "communication network" refers to a network that conforms to any suitable communication standard, such as New Radio (NR), long Term Evolution (LTE), LTE-advanced (LTE-a), wideband Code Division Multiple Access (WCDMA), high Speed Packet Access (HSPA), non-terrestrial network (NTN), narrowband internet of things (NB-IoT), and the like. Furthermore, the communication between the terminal device and the network device in the communication network may be performed according to any suitable generation communication protocol, including, but not limited to, first generation (1G), second generation (2G), 2.5G, 2.75G, third generation (3G), fourth generation (4G), 4.5G, future fifth generation (5G) communication protocols, and/or any other protocol currently known or to be developed in the future. Embodiments of the present disclosure may be applied to various communication systems including, but not limited to, terrestrial communication systems, non-terrestrial communication systems, or combinations thereof. In view of the rapid development of communications, there are of course future types of communication technologies and systems with which the present disclosure may be implemented. And should not be taken as limiting the scope of the invention to only the above-described systems.

As used herein, the term "network device" refers to a node in a communication network via which a terminal device accesses the network and receives services therefrom. Depending on the terminology and technology applied, a network device may refer to a Base Station (BS) or Access Point (AP), e.g., a node B (node B or NB), an evolved node B (eNodeB or eNB), an NR NB (also known as a gNB), a Remote Radio Unit (RRU), a Radio Head (RH), a Remote Radio Head (RRH), a relay, a low power node such as a femto, pico, non-terrestrial network (NTN) or non-terrestrial network device such as a satellite network device, a Low Earth Orbit (LEO) satellite and Geosynchronous Earth Orbit (GEO) satellite, an aircraft network device, etc.

The term "terminal device" refers to any terminal device capable of wireless communication. By way of example and not limitation, a terminal device may also be referred to as a communication device, user Equipment (UE), subscriber Station (SS), portable subscriber station, mobile Station (MS), or Access Terminal (AT). The terminal devices may include, but are not limited to, mobile phones, cellular phones, smart phones, voice over IP (VoIp) phones, wireless local loop phones, tablet computers, wearable terminal devices, personal Digital Assistants (PDAs), portable computers, desktop computers, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback devices, in-vehicle wireless terminal devices, wireless endpoints, mobile stations, laptop embedded devices (LEEs), laptop mounted devices (LMEs), USB dongles, smart devices, wireless client devices (CPE), internet of things (IoT) devices, watches or other wearable devices, head Mounted Displays (HMDs), vehicles, drones, medical devices and applications (e.g., tele-surgery), industrial devices and applications (e.g., robots and/or other wireless devices operating in an industrial and/or automated processing chain environment), consumer electronic devices, devices operating on a commercial and/or industrial wireless network, and the like. In the following description, the terms "terminal device", "communication device", "terminal", "user equipment" and "UE" may be used interchangeably.

NB-IoT supports fixed and low mobility terminal devices that operate primarily in RRC idle states, which may also be referred to as NB-IoT terminal devices. As mentioned above, in DRX and eDRX schemes, NB-IoT terminal devices periodically enter a deep sleep state during a corresponding DRX or eDRX cycle and wake up during a PTW that also includes one or more Paging Occasions (POs) for monitoring a Narrowband Physical Downlink Control Channel (NPDCCH). Meanwhile, cell measurement activities, such as Reference Signal Received Power (RSRP), reference Signal Received Quality (RSRQ) measurements related to cell selection and reselection procedures in idle mode, may be performed at the terminal device during the PO.

In conventional communication systems, standards S and R are widely used for cell selection and reselection procedures. In particular, at the beginning of each PO, the terminal device may perform intra-frequency or inter-frequency measurements of RSRP on its serving cell and neighboring cells. In the context of the present disclosure, the serving cell may also be referred to as a source cell. The standard S is represented by the following formula (1):

S _rxlev ＝ Q _rxlevmeas – Q _rxlevmin – P _compensation – Q _offset (1)

wherein S is _rxlev A value (dB) representing a cell selection reception level; q (Q) _rxlevmeas A cell reception level value (e.g., RSRP) representing the measurement; q (Q) _rxlevmin Representing the minimum reception level value, P, required by the cell _compensation And Q _offset Is a numerical operator configurable or settable by the network.

In the case of intra-frequency measurement, if S _rxlev Exceeding the threshold of intra-frequency measurement, S _IntraSearchP I.e. if S _rxlev >S _IntraSearchP The terminal device determines not to perform intra-frequency measurements. Otherwise, if S _rxlev ≤S _IntraSearchP The terminal device may perform intra-frequency measurements.

Similarly, in the case of inter-frequency measurements, if S _rxlev Without exceeding the threshold of inter-frequency measurement, S _{nonIntraSearchP} I.e. if S _rxlev ≤S _{nonIntraSearchP} The terminal device may perform inter-frequency measurements. By means of the cell selection criterion S, the measurements required for cell reselection can be limited, thereby saving power consumption at the terminal device.

As mentioned above, at S _rxlev Below the threshold S of intra-frequency measurement _IntraSearchP In the following period, the terminal device measures RSRP of the serving cell and the neighboring cell, and sorts the measurement results according to the cell reselection criteria R. The serving cell level Rs and the neighbor cell level Rn as comparison parameters for cell reselection can be expressed by the following formulas (2) - (3):

Rs ＝ Q _meas,s + Q _Hyst (2)

Rn ＝ Q _meas,n – Q _offset (3)

wherein Q is _meas,s And Q _meas,n Values representing RSRP measured for the serving cell and the neighboring cell, respectively; q (Q) _Hyst Hysteresis value representing cell reselection, while Q _offset Representing measurements for a serving cell and corresponding neighboring cells Is an offset between RSRP of (b).

If the cell is ranked as the best cell, the terminal device may perform a cell reselection procedure and switch to that cell. Furthermore, the terminal device can reselect a new serving cell only if the following conditions are met: 1) At time interval T _{reselectionRAT} During this period, the new cell is better ranked than the serving cell; and 2) more than 1 second has elapsed since the terminal device camped on the current serving cell.

As communication technologies have evolved to 5G NR, HO and cell selection/reselection procedures for terminal devices may be performed between NTN cells provided by NTN devices, including but not limited to satellites, such as Low Earth Orbit (LEO) satellites, high Altitude Platforms (HAPS), unmanned Aerospace Surveillance (UAS) platforms, and the like. The 5G NR NTN is fundamentally different from the terrestrial access network and thus new mobility mechanisms and/or triggers may be required to ensure good performance and minimize the delay of the terminal equipment.

In NTN, for example, in the LEO satellite scenario, it is unlikely that the terminal device stays within the coverage of the same NTN cell for a long time due to the speed of the LEO satellite. In this way, even for fixed terminal equipment, the HO and cell selection/reselection procedures may occur frequently and inevitably. Regarding minimum cell diameter (e.g., 50 km) and maximum cell diameter (e.g., 1000 km) and relative speed, the maximum period of time that the NB-IoT terminal device remains in the NTN cell, i.e., the duration from the time that the terminal device enters the coverage of the NTN cell at the edge of one cell to the time that the terminal device leaves the coverage at the opposite edge of the cell, is listed in table 1 below.

Table 1 cell diameter and relative speeds of terminal devices

As shown above, regardless of the mobility of the terminal device, it can maintain the maximum time of connection for 6.61 seconds and 132.38 seconds in the same NTN LEO cells having diameters of 50km and 1000km, respectively, due to the movement of the LEO satellite. For NB-IoT, the maximum value of eDRX period was extended to 10485.76 seconds, which is equal to 2.91 hours. It is contemplated that multiple LEO satellites may have crossed the terminal device when the terminal device wakes up from the eDRX cycle and attempts to receive paging messages during PTW. In this case the terminal device is already located outside the coverage of the source cell and thus has been disconnected from the satellite managing the source cell. If the terminal device still performs the cell reselection procedure according to the standards S and R, redundancy and unnecessary measurements will be performed on the serving cell, resulting in power waste and undesirable delays for camping on the target cell.

To reduce power consumption, speed up cell selection and/or reselection procedures for terminal devices, and to address further potential problems, the present disclosure provides a fast and efficient cell reselection mechanism for NB-IoT. In the cell selection/reselection mechanism, the terminal device is configured with cell selection information indicating conditions for performing a simplified and fast cell selection procedure. If the condition is met, the terminal device will directly perform the cell selection procedure without measuring and judging the source cell. Otherwise, if the condition is not satisfied, the terminal device may perform a cell reselection procedure in a conventional manner. In this way, delays due to cell selection and/or reselection and power consumption at the terminal device may be reduced.

Fig. 1A and 1B illustrate an example communication environment 100 in which embodiments of the present disclosure may be implemented. In particular, fig. 1A shows the communication network 100 at a first time instant T1, while fig. 1B shows the communication network 100 at a second time instant T2 after the first time instant T1. As shown, the communication network 100 includes a first device 110 and a set of network devices including a second device 120, a third device 130, a fourth device 140, a fifth device 150, and so on. It should also be understood that the number of network devices, terminal devices and cells shown in fig. 1A and 1B are given for illustrative purposes and do not imply any limitation.

The set of network devices may be NTN devices that move around the earth's surface. As an example, the second device 120-fifth device 150 may be deployed at a satellite or UAS platform and assume that one or more beams (e.g., satellite beams) for providing a service area can be generated. The service areas of the second device 120, the third device 130, the fourth device 140, and the fifth device 150 may be referred to as cells, such as

cells

122, 132, 142, and 152.

To reduce power consumption, the first device 110 may be a terminal device having low or no mobility and operating in an RRC idle state, for example, by using eDRX scheme. Fig. 2 illustrates a schematic diagram of an example eDRX scheme 200, according to some example embodiments of the present disclosure. As shown in fig. 2, in the eDRX scheme 200, the first device 110 periodically enters a deep sleep state in the eDRX cycle 210 and wakes up during the POs 221-224 of the PTW 220 to receive the paging message. During PTW, the first device 110 monitors a downlink channel, such as NPDCCH, between the first device 110 and a network device (e.g., the second device 120) currently serving the first device 110. Further, at the POs 221-224, the first device 110 can measure RSRP and RSRQ related to cell selection or reselection on the cells 122-152.

Returning to fig. 1A and 1B, as above, the set of network devices are NTN devices that move around the earth's surface, such as LEO satellite constellations. In this case, each NTN device in the group may serve the first device 110 at a certain service time. As shown in fig. 1A, at a first time instant T1, a first device 110 is located within a cell 122 and is served by a second device 120. In other words, the cell 122 is the source cell of the first device 110. As time reaches a second time instant T2 shown in fig. 1B, the second device 120 moves away and the third device 130 moves over the first device 110. At this time, the first device 110 is located within the coverage (i.e., cell 132) of the third device 130.

It should be understood that eDRX schemes and specific configurations are set forth herein as examples and should not be construed as imposing any limitation on the scope of the present disclosure. In some example embodiments, a DRX scheme or any other power saving scheme (existing or to be developed in the future) is also possible and suitable.

In the communication environment 100 as shown in fig. 1A and 1B, respective NTN devices including a second device 120, a third device 130, a fourth device 140, and a fifth device 150 may transmit data and control information to the first device 110. The first device 110 may also communicate data and control information to the corresponding network devices 120-150. The link from each network device 120 to 150 to the first device 110 is referred to as a Downlink (DL), and the link from the first device 110 to a corresponding one of the network devices 120 to 150 is referred to as an Uplink (UL).

Communication in communication environment 100 may be implemented in accordance with any suitable communication protocol including, but not limited to, first generation (1G), second generation (2G), third generation (3G), fourth generation (4G), fifth generation (5G), etc., cellular communication protocols, wireless local area network communication protocols such as Institute of Electrical and Electronics Engineers (IEEE) 802.11, etc., and/or any other protocol currently known or developed in the future. Further, the communication may utilize any suitable wireless communication technology including, but not limited to: code Division Multiple Access (CDMA), frequency Division Multiple Access (FDMA), time Division Multiple Access (TDMA), frequency division duplex (FD), time Division Duplex (TDD), multiple Input Multiple Output (MIMO), orthogonal Frequency Division Multiplexing (OFDM), discrete fourier transform spread OFDM (DFT-s-OFDM), and/or any other technique currently known or developed in the future.

There are several aspects of mobility for the terminal device and the network device that need to be addressed, including cell selection, reselection, handover, etc. According to an example embodiment of the present disclosure, a solution for cell selection and reselection for a terminal device in an idle state is provided. More specifically, instead of repeatedly performing measurements on the source cell and the neighboring cell, cell selection information is provided to the terminal device for indicating conditions under which the simplified actual cell selection procedure is performed. While the proposed solution is described in the context of NTN scenarios, it should be understood that the solutions provided in the example embodiments of the present disclosure are also applicable to legacy terrestrial networks. For example, the proposed solution may also be applicable to ground scenarios, such as vehicles or trains in highways, as well as some HAPS scenarios.

The principles and embodiments of the present disclosure will be described in detail below with reference to fig. 3 to 5. Fig. 3 illustrates a signaling flow for a cell selection process 300 according to some example embodiments of the present disclosure. For discussion purposes, the process 300 will be described with reference to fig. 1A and 1B. The process 300 may involve the first device 110, the second device 120, and the third device 130.

As described above in connection with fig. 1-2, the first device 110 is initially located in the source cell 122 and served by the second device 120. The second device 120 determines 302 cell selection information for supporting DRX or eDRX at the first device 110. The cell selection information is configured to cause the first device 110 to: the target cell for the first device 110 is selected, while during the paging transmission window, no measurements are made of the source cell 122 after waking up from the corresponding DRX or eDRX cycle, as will be discussed in detail below. The target cell may be managed by a network device (e.g., third device 130) that is different from second device 120.

In some example embodiments, the cell selection information may be a time threshold associated with at least one service time of the set of network devices 120 to 150. As an example, the time threshold may be determined as a minimum service time among service times of the second device 120, the third device 130, the fourth device 140, and the fifth device 150. Such a time threshold may assist the first device 110 in determining whether it is still in the source cell 122 after waking up from the eDRX cycle. In particular, in the event that the eDRX period exceeds a time threshold, it indicates that the first device 110 may no longer be located within the source cell 122 when it wakes up from the eDRX period. Otherwise, the first device 110 may remain in the source cell 122 after waking up from the eDRX cycle if the eDRX cycle does not exceed the time threshold.

In some other example embodiments, the cell selection information may be an indicator for triggering selection of the target cell without measurement of the source cell 122. In these embodiments, the second device 120 may determine whether the first device 110 is still within the source cell 122 after the first device 110 wakes up from the eDRX cycle based on the eDRX cycle and a time threshold associated with at least one service time of the set of network devices 120-150. For example, if the second device 120 determines that the eDRX period of the first device 110 exceeds a time threshold, the second device 120 may set an indicator to a first value (e.g., 0) indicating a direct cell selection procedure without taking measurements of the source cell 122. If the second device 120 determines that the eDRX period of the first device 110 does not exceed the time threshold, the second device 120 may set the indicator to a second value (e.g., 1) instructing the first device 110 to perform conventional procedures, such as first making measurements on the source cell 122 and then making measurements on neighboring cells according to the criteria S and R.

In other example embodiments, the second device 120 may send an indicator to the first device 110 if the second device 120 determines that the eDRX period of the first device 110 exceeds a time threshold. Otherwise, if the second device 120 determines that the eDRX period of the first device 110 does not exceed the time threshold, an indicator will not be sent from the second device 120, implicitly instructing the first device 110 to perform a legacy procedure.

The second device 120 sends 304 a first message comprising at least cell selection information to the first device 110. In some example embodiments, the second device 120 may broadcast the first message to the first device 110. The first message may include cell selection information and a set of parameters related to cell reselection including, but not limited to, Q _rxlevmin 、P _compensation 、Q _offset Corresponding DRX or eDRX cycle, etc.

Upon receiving the first message, the first device 110 may store the cell selection information locally and then it enters the eDRX cycle, i.e., is in a deep sleep state. After waking up during PTW, e.g. at time instant t ₂ The first device 110 may already be outside the cell 122 and located within the cell 132 provided by the third device 130.

In some example embodiments, the first device 110 determines that it has moved out of the source cell 122 and may omit the measurement of the source cell 122 based on the cell selection information. In this case, the first device 110 selects 306 the target cell without making measurements on the source cell 122 based on the cell selection information. In this example, the target cell is a cell 132 managed by the third device 130. The first device 110 may then perform 308 communication with the third device 130 on the target cell 132. For example, the first device 110 may perform a cell search, receive a Master Information Block (MIB), a System Information Block (SIB), and so on from the third device 130. The cell selection procedure may follow any mechanism known or developed in the future, and thus the relevant description is omitted here to avoid redundancy.

In the event that no cell selection information is present, or cell selection information of a second value, or additionally, the eDRX period of the first device 110 does not exceed a time threshold indicated by the cell selection information, the first device 110 may perform a cell search and reselection procedure to determine the target cell. Specifically, the first device 110 may first perform measurements on the source cell 122. For example, the first device 110 may measure the RSRP or RSRQ of the source cell 122 and determine whether the cell selection condition is met, e.g., by employing criterion S. When the cell selection condition is satisfied (e.g., S _rxlev ≤S _IntraSearchP ) In the case of (a), the first device 110 performs cell search and measurement on neighbor cells.

The first device 110 may then select a target cell from among the neighboring cells based on the cell search and the measurement results. For example, the first device 110 may determine the target cell based on the criterion R. After determining the target cell, the first device 110 performs a cell reselection procedure to the target cell. The cell reselection procedure may follow any known or existing mechanism or any mechanism that will be developed in the future, and thus a description thereof is omitted here to avoid redundancy.

According to an example embodiment of the present disclosure, cell selection information is provided for assisting the terminal device in determining whether it has moved out of the source cell and is already under the coverage of a new network device (e.g., a new satellite) before performing any measurements. In this way, redundant measurements and decisions as to whether it has moved out of coverage of the source cell can be avoided. In this way, fast cell selection and reselection procedures can be implemented at terminal devices with low power consumption.

Fig. 4 illustrates a flowchart of a cell selection method 400 according to some example embodiments of the present disclosure. The method 400 may be implemented at a terminal device, such as the first device 110 described with reference to fig. 1A and 1B. The method 400 may also include the second device 120 and the third device 130. It should be understood that method 400 may include additional acts not shown and/or may omit some of the acts shown, and the scope of the present disclosure is not limited in this respect. Further, it should be appreciated that although primarily presented herein as being performed sequentially, at least a portion of the acts of process 400 may be performed concurrently or in a different order than presented in FIG. 4.

At 410, the first device 110 receives a first message from a second device 120 that manages a source cell 122 of the first device 110. The first message includes at least cell selection information for supporting DRX or eDRX at the first device 110. In some example embodiments, the first message may be broadcast from the second device 120 and further include a set of parameters related to cell reselection, such as Q _rxlevmin 、P _compensation 、Q _offset Corresponding DRX or eDRX cycle, etc. In this case, the cell selection information is transmitted together with parameters related to cell reselection. In some exemplary other embodiments, the cell selection information may be transmitted separately from the parameters related to cell reselection.

Upon receiving the first message, the first device 110 may store the cell selection information locally and may then enter a sleep state during the eDRX cycle. In some example embodiments, after waking up from the eDRX cycle, the first device 110 may enter the PTW to receive paging messages and perform measurements in radio coverage. In this case, the first device 110 performs a cell selection and reselection procedure based on the cell selection information.

At 420, the first device 110 selects the target cell 132 based on the cell selection information, while during PTW, no measurements are made of the source cell 122 after waking up from the corresponding DRX cycle or eDRX cycle. The target cell 132 is managed by a third device 130 different from the second device 120.

In some example embodiments, the cell selection information may include a time threshold associated with at least one service time of the set of network devices 120 to 150. For example, the time threshold may be determined by the second device 120 as a minimum service time among the service times of the second device 120, the third device 130, the fourth device 140, and the fifth device 150. The first device 110 may compare the eDRX cycle to a time threshold. If the eDRX period exceeds a time threshold, which indicates that the first device 110 may no longer be within the source cell 122 after waking up from the eDRX period, the first device 110 may select the target cell 132 without making measurements on the source cell 122 during PTW. For example, the first device 110 may skip measurements on the source cell 122 and perform cell search and measurements directly on the neighboring cells 132-152.

In some example embodiments, the cell selection information may include an indicator to trigger selection of the target cell without taking measurements of the source cell 122. For example, an indicator included in the cell selection information may be set to a first value (e.g., 0) to indicate that the eDRX period of the first device 110 exceeds a time threshold associated with the service time of the set of network devices 120-150, or simply to indicate that a cell is selected without performing measurements on the source cell. In this case, the first device 110 may select the target cell 132 without making measurements on the source cell 122 during PTW.

In the above-described embodiment, if the indicator is set to the second value (e.g., 1) or the indicator is not present in the first message, the first device 110 may determine that the measurement of the source cell 122 cannot be skipped and a legacy procedure will be performed.

In some example embodiments, the first device 110 may be a terminal device, and the second device 120 and the third device 130 may be network devices, such as NTN devices deployed at satellites, UAVs, and the like.

Fig. 5 illustrates a flowchart of a cell selection method 500 according to some example embodiments of the present disclosure. The method 500 may be implemented at a network device, such as the second device 120 described with reference to fig. 1A and 1B. The method 500 may also include the first device 110. It should be understood that method 500 may include additional acts not shown and/or may omit some of the acts shown, and the scope of the present disclosure is not limited in this respect. Further, it should be appreciated that although primarily presented herein as being performed sequentially, at least a portion of the acts of process 500 may be performed concurrently or in a different order than presented in FIG. 5.

At 510, the second device 120 determines cell selection information for supporting DRX or eDRX at the first device 110. The source cell 122 of the first device 110 is managed by the second device 120. The cell selection information may include a time threshold associated with at least one service time of the set of network devices 120 to 150. For example, the second device 120 may determine the time threshold as a minimum service time or an average service time of service times of the second device 120, the third device 130, the fourth device 140, and the fifth device 150.

In some other example embodiments, the cell selection information may include an indicator to trigger selection of the target cell without measurement of the source cell 122. The indicator included in the cell selection information may have a first value (e.g., 0) indicating that direct selection of the target cell is triggered without measurement of the source cell and a second value (e.g., 1) indicating that such direct target cell selection is not triggered and indicating a legacy procedure to be performed.

Alternatively, in some other example embodiments, the second device 120 may send an indicator indicating direct target cell selection in the event that the second device 120 may determine that the eDRX period exceeds a time threshold associated with the service time of the set of network devices 120-150. In the event that the second device 120 can determine that the eDRX period does not exceed a time threshold associated with the service time of the set of network devices 120-150, no indicator will be sent from the second device 120.

At 520, the second device 120 includes a first message of cell selection information to the first device 110. The cell selection information may cause the first device 110 to: the target cell 132 is selected and during PTW no measurements are made of the source cell 122 after waking up from the corresponding DRX or eDRX cycle. In this case, the target cell 132 is managed by a third device 130 different from the second device 120.

In some example embodiments, the second device 120 may broadcast the first message to the first device 110. As an example, the first message may also include a phase with cell reselectionA related set of parameters, e.g. Q _rxlevmin 、P _compensation 、Q _offset Corresponding DRX or eDRX cycle, etc. In this case, the cell selection information is transmitted together with parameters related to cell reselection. For another example, the cell selection information may be sent separately from parameters related to cell reselection. The present disclosure is not limited in this respect.

In some example embodiments, a first apparatus capable of performing the method 400 may include means for performing the respective steps of the method 400. The component may be implemented in any suitable form. For example, the components may be implemented in circuitry or software modules.

In some example embodiments, the first apparatus includes: receiving a first message from a second device, the second device managing a source cell of the first device, the first message including at least cell selection information for supporting discontinuous reception or extended discontinuous reception at the first device; and means for selecting a target cell for the first device based on the cell selection information, without measuring the source cell after waking up from a corresponding discontinuous reception or extended discontinuous reception period during the paging transmission window, the target cell being managed by a third device different from the second device.

In some example embodiments, the means for receiving the first message comprises: means for receiving a first message comprising a set of parameters related to cell reselection, and cell selection information.

In some example embodiments, the cell selection information includes a time threshold associated with at least one service time for a set of network devices serving the first apparatus, and the means for selecting the target cell includes: means for selecting the target cell in accordance with determining that the corresponding discontinuous reception or extended discontinuous reception period exceeds the time threshold without making measurements on the source cell during the paging transmission window.

In some example embodiments, the time threshold is determined as a minimum service time of at least one service time of a set of network devices for serving the first apparatus.

In some example embodiments, the cell selection information includes an indicator for triggering selection of the target cell without measurement of the source cell, and the means for selecting the target cell includes: in accordance with a determination that the cell selection information includes an indicator, selecting the target cell without making measurements on the source cell during the paging transmission window.

In some example embodiments, the first apparatus is a terminal device, the second apparatus is a network device, and the third apparatus is a further network device.

In some example embodiments, a second apparatus capable of performing the method 500 may include means for performing the respective steps of the method 500. The component may be implemented in any suitable form. For example, the components may be implemented in circuitry or software modules.

In some example embodiments, the second apparatus includes: means for determining cell selection information for supporting discontinuous reception or extended discontinuous reception at a first device, a source cell of the first device being managed by a second device; and means for sending a first message including at least cell selection information to the first apparatus, the cell selection information being used to cause the first apparatus to: the target cell for the first device is selected and during the paging transmission window, after waking up from a corresponding discontinuous reception or extended discontinuous reception period, no measurements are made of the source cell, the target cell being managed by a third device different from the second device.

In some example embodiments, the cell selection information comprises a time threshold associated with at least one service time for a set of network devices serving the first apparatus, and the means for determining the cell selection information comprises: means for determining a time threshold based on at least one service time of the set of network devices.

In some example embodiments, the means for determining the time threshold comprises: means for determining a time threshold as a minimum service time of at least one service time of the set of network devices for serving the first apparatus.

In some example embodiments, the cell selection information includes an indicator for triggering selection of the target cell without measurement of the source cell, and the means for determining the cell selection information includes: means for determining a time threshold based on at least one service time of the set of network devices for serving the first apparatus; and means for determining an indicator for triggering selection of the target cell without measurement of the source cell during the paging transmission window in accordance with a determination that the corresponding discontinuous reception or extended discontinuous reception period exceeds a time threshold.

In some example embodiments, the means for sending the first message comprises: means for transmitting a first message comprising cell selection information and a set of parameters related to cell reselection.

Fig. 6 is a simplified block diagram of a device 600 suitable for implementing embodiments of the present disclosure. The device 600 may be provided to implement communication devices such as the first device 110, the second device 120, and the third device 130 shown in fig. 1A and 1B. As shown, the device 600 includes one or more processors 610, one or more memories 620 coupled to the processors 610, and one or more communication modules 640 coupled to the processors 610.

The communication module 640 is used for two-way communication. The communication module 640 has at least one antenna to facilitate communication. The communication interface may represent any interface required to communicate with other network elements.

The processor 610 may be of any type suitable to the local technology network and may include, as non-limiting examples, one or more of the following: general purpose computers, special purpose computers, microprocessors, digital Signal Processors (DSPs), and processors based on a multi-core processor architecture. The device 600 may have multiple processors, such as application specific integrated circuit chips that are temporally slaved to a clock that synchronizes the master processor.

Memory 620 may include one or more non-volatile memories and one or more volatile memories. Examples of non-volatile memory include, but are not limited to, read-only memory (ROM) 624, electrically programmable read-only memory (EPROM), flash memory, a hard disk, a Compact Disk (CD), a Digital Video Disk (DVD), and other magnetic and/or optical storage devices. Examples of volatile memory include, but are not limited to, random Access Memory (RAM) 622 and other volatile memory that does not last for the duration of the power outage.

The computer program 630 includes computer-executable instructions that are executed by the associated processor 610. Program 630 may be stored in ROM 620. Processor 610 may perform any suitable actions and processes by loading program 630 into RAM 620.

Embodiments of the present disclosure may be implemented by means of program 630 such that device 600 may perform any of the processes of the present disclosure as discussed with reference to fig. 3-5. Embodiments of the present disclosure may also be implemented in hardware or a combination of software and hardware.

In some embodiments, program 630 may be tangibly embodied in a computer-readable medium that may be included in device 600 (e.g., in memory 620) or other storage device accessible by device 600. Device 600 may load program 630 from a computer readable medium into RAM 622 for execution. The computer readable medium may include any type of tangible, non-volatile memory, such as ROM, EPROM, flash memory, hard disk, CD, DVD, etc. Fig. 7 shows an example of a computer readable medium 700 in the form of a CD or DVD. The computer readable medium has stored thereon the program 630.

In general, the various embodiments of the disclosure may be implemented using hardware or special purpose circuits, software, logic or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. While various aspects of the embodiments of the disclosure are illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer-readable storage medium. The computer program product comprises computer executable instructions, such as instructions included in a program module, that are executed in a device on a target real or virtual processor to perform the

method

400 or 500 as described above with reference to fig. 4-5. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, etc. that perform particular tasks or implement particular abstract data types. In various embodiments, the functionality of the program modules may be combined or split between program modules as desired. Machine-executable instructions of program modules may be executed within local or distributed devices. In a distributed device, program modules may be located in both local and remote memory storage media.

Program code for carrying out the methods of the present disclosure may be written in any combination of one or more programming languages. These program code may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus such that the program code, when executed by the processor or controller, causes the functions/operations specified in the flowchart and/or block diagram to be implemented. The program code may execute entirely on the machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine, or entirely on the remote machine or server

In the context of this disclosure, computer program code or related data may be carried by any suitable carrier to enable an apparatus, device or processor to perform the various processes and operations described above. Examples of carriers include signals, computer readable media, and the like.

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 a computer-readable storage medium would include an electrical connection having one or more wires, a portable computer diskette, 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.

Further, while operations are described in a particular order, this should not be construed as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In some cases, multitasking and parallel processing may be advantageous. Also, while several specific implementation details are included in the above discussion, these should not be construed as limitations on the scope of the disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination.

Although the disclosure has been described in language specific to structural features and/or methodological acts, it is to 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 first device, comprising:

at least one processor; and

at least one memory including computer program code;

wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the first device at least to:

receiving a first message from a second device, the second device managing a source cell of the first device, the first message including at least cell selection information for supporting discontinuous reception or extended discontinuous reception at the first device; and

a target cell for the first device is selected based on the cell selection information, without making measurements on the source cell after waking up from a corresponding discontinuous reception period or an extended discontinuous reception period during a paging transmission window, the target cell being managed by a third device different from the second device.

2. The first device of claim 1, wherein the first device is caused to receive the first message by:

the first message including a set of parameters related to cell reselection and the cell selection information is received.

3. The first device of claim 1, wherein the cell selection information comprises a time threshold associated with at least one service time for a group of network devices serving the first device, and wherein the first device is caused to select the target cell by:

in accordance with a determination that the corresponding discontinuous reception period or extended discontinuous reception period exceeds the time threshold, the target cell is selected without measuring the source cell during the paging transmission window.

4. A first device as claimed in claim 3, wherein the time threshold is determined as: a minimum service time of the at least one service time of the set of network devices for serving the first device.

5. The first device of claim 1, wherein the cell selection information comprises an indicator to trigger the selection of the target cell without measurement of the source cell, and wherein the first device is caused to select the target cell by:

In accordance with a determination that the cell selection information includes the indicator, the target cell is selected without making measurements on the source cell during the paging transmission window.

6. The first device of claim 1, wherein the first device is a terminal device, the second device is a network device, and the third device is a further network device.

7. A second device, comprising:

at least one processor; and

at least one memory including computer program code;

wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the second device to at least:

determining cell selection information for supporting discontinuous reception or extended discontinuous reception at a first device, a source cell of the first device being managed by the second device; and

transmitting, to the first device, a first message including at least the cell selection information for causing the first device to: a target cell for the first device is selected, and during a paging transmission window, after waking up from a corresponding discontinuous reception period or an extended discontinuous reception period, no measurements are made on the source cell, the target cell being managed by a third device different from the second device.

8. The second device of claim 7, wherein the cell selection information comprises a time threshold associated with at least one service time for a group of network devices serving the first device, and wherein the second device is caused to determine the cell selection information by:

the time threshold is determined based on the at least one service time of the set of network devices.

9. A second device as claimed in claim 8, wherein the second device is caused to determine the time threshold by:

determining the time threshold as: a minimum service time of the at least one service time of the set of network devices for serving the first device.

10. The second device of claim 7, wherein the cell selection information comprises an indicator for triggering the selection of the target cell without measurement of the source cell, and wherein the second device is caused to determine the cell selection information by:

determining a time threshold based on at least one service time of a set of network devices serving the first device; and

In accordance with a determination that the corresponding discontinuous reception period or extended discontinuous reception period exceeds the time threshold, an indicator is determined that triggers the selection of the target cell without measurement of the source cell during the paging transmission window.

11. The second device of claim 7, wherein the second device is caused to send the first message by:

the first message comprising the cell selection information and a set of parameters related to cell reselection is sent.

12. The second device of claim 7, wherein the first device is a terminal device, the second device is a network device, and the third device is a further network device.

13. A method, comprising:

receiving, at a first device, a first message from a second device, the second device managing a source cell of the first device, the first message including at least cell selection information for supporting discontinuous reception or extended discontinuous reception at the first device; and

14. The method of claim 13, wherein receiving the first message comprises:

15. The method of claim 13, wherein the cell selection information comprises a time threshold associated with at least one service time for a set of network devices serving the first device, and wherein selecting the target cell comprises:

16. The method of claim 15, wherein the time threshold is determined as: a minimum service time of the at least one service time of the set of network devices for serving the first device.

17. The method of claim 13, wherein the cell selection information includes an indicator for triggering the selection of the target cell without measurement of the source cell, and wherein selecting the target cell comprises:

18. The method of claim 13, wherein the first device is a terminal device, the second device is a network device, and the third device is a further network device.

19. A method, comprising:

determining, at a second device, cell selection information for supporting discontinuous reception or extended discontinuous reception at a first device, a source cell of the first device being managed by the second device; and

20. The method of claim 19, wherein the cell selection information comprises a time threshold associated with at least one service time for a set of network devices serving the first device, and wherein determining the cell selection information comprises:

21. The method of claim 20, wherein determining the time threshold comprises:

22. The method of claim 19, wherein the cell selection information comprises an indicator for triggering the selection of the target cell without measurement of the source cell, and wherein determining the cell selection information comprises:

23. The method of claim 19, wherein sending the first message comprises:

24. The method of claim 19, wherein the first device is a terminal device, the second device is a network device, and the third device is a further network device.

25. A first apparatus, comprising:

means for receiving, at the first apparatus, a first message from a second apparatus, the second apparatus managing a source cell of the first device, the first message including at least cell selection information for supporting discontinuous reception or extended discontinuous reception at the first apparatus; and

means for selecting a target cell for the first device based on the cell selection information without making measurements on the source cell after waking up from a corresponding discontinuous reception period or an extended discontinuous reception period during a paging transmission window, the target cell being managed by a third device different from the second device.

26. A second apparatus, comprising:

means for determining, at a second device, cell selection information for supporting discontinuous reception or extended discontinuous reception at a first device, a source cell of the first device being managed by the second device; and

Means for sending a first message comprising at least the cell selection information to the first apparatus, the cell selection information being for causing the first apparatus to: a target cell for the first device is selected, and during a paging transmission window, after waking up from a corresponding discontinuous reception period or an extended discontinuous reception period, no measurements are made on the source cell, the target cell being managed by a third device different from the second device.

27. A non-transitory computer readable medium comprising program instructions for causing an apparatus to perform at least the method of any one of claims 13-18.

28. A non-transitory computer readable medium comprising program instructions for causing an apparatus to perform at least the method of any one of claims 19-24.