Adaptation of mobility measurements in non-terrestrial networks

Abstract

According to an aspect, there is provided a user equipment, UE, for performing the following. Based on a serving cell of the user equipment, being provided by a first satellite, having a first neighbor cell provided by a second satellite, the UE determines whether a downlink opportunity of the first neighbor cell overlaps with a downlink opportunity of the serving cell currently usable by the user equipment when the user equipment is operating in an idle mode. Based on the downlink opportunity of the first neighbor cell not overlapping with the downlink opportunity of the serving cell currently usable by the user equipment, the UE sets a scaling factor for a cell reselection process involving one or more satellites to be equal to 1. The scaling factor is usable, at the user equipment, for scaling timing of least one of: cell detection, cell measurements or cell evaluation for cell reselection.

Description

ADAPTATION OF MOBILITY MEASUREMENTS IN NON-TERRESTRIAL NETWORKSFIELD

[0001] Various example embodiments relate to non-terrestrial cellular communications.BACKGROUND

[0002] Non-terrestrial network (NTN) refers to communication network infrastructure in which at least one of the network elements is positioned or operates outside of Earth's terrestrial surface. NTNs may utilize, for example, satellites, for providing wireless communication services. Said satellites usable in NTNs may comprise, for example, low Earth orbit (LEO) satellites which may reach speeds of up to 7600 m / s. This presents challenges for the operation of the NTN as user equipment (UE) can only measure the radio signals transmitted by such LEO satellites for a limited amount of time before the satellite disappears beyond the horizon or the cell is switched away. Moreover, in LEO scenarios, the relative speed of the satellite imposes significant Doppler offsets which need to be post compensated by the UEs in downlink. Recently, adoption of Internet of Things (loT) time division duplexing (TDD) in narrowband Internet of Things (NB-IoT) in NTNs has been suggested. Said problems need to be addressed in the implementation of said loT TDD for NB-IoT.SUMMARY

[0003] According to some aspects, there is provided the subject-matter of the independent claims. Some example embodiments are defined in the dependent claims.

[0004] The scope of protection sought for various example embodiments of the disclosure is set out by the independent claims. The example embodiments and features, if any, described in this specification that do not fall under the scope of the independent claims are to be interpreted as examples useful for understanding various example embodiments of the disclosure.

[0005] According to a first aspect, there is provided an apparatus comprising:at least one processor; andat least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform:based on a serving cell, provided by a first satellite, having a neighbor cell provided by a second satellite,- determining whether a downlink opportunity of the neighbor cell overlaps with any communication opportunity of the serving cell currently usable by the apparatus, and - based on the downlink opportunity of the neighbor cell not overlapping with any communication opportunity of the serving cell currently usable by the apparatus, setting a scaling factor for a cell reselection process involving one or more satellites to be equal to 1, wherein the scaling factor is usable, at the apparatus, for scaling timing of least one of: cell detection, cell measurements or cell evaluation for cell reselection.

[0006] According to a first embodiment of the first aspect, the at least one memory and the instructions are configured, with the at least one processor, to cause the apparatus to perform, based on the serving cell having the neighbor cell provided by the second satellite,- based on the downlink opportunity of the neighbor cell overlapping with a communication opportunity of the serving cell currently usable by the apparatus, setting the scaling factor to be equal to 2

[0007] According to a second embodiment of the first aspect, the neighbor cell is a first neighbor cell, and the at least one memory and the instructions are configured, with the at least one processor, to cause the apparatus to perform:based on the downlink opportunity of the first neighbor cell not overlapping with any communication opportunity of the serving cell currently usable by the apparatus,- determining whether the serving cell has a second neighbor cell provided by a third satellite and having no downlink opportunity overlapping with said any communication opportunity of the serving cell;- based on the serving cell having the second neighbor cell provided by the third satellite and having no downlink opportunity overlapping with said any communication opportunity of the serving cell, enabling radio measurements of the second neighbor cell, in addition to the serving cell and the first neighbor cell, and setting the scaling factor to be equal to 2

[0008] According to a third embodiment of the first aspect, the at least one memory and the instructions are configured, with the at least one processor, to cause the apparatus to perform:based on the serving cell having no neighbor cell provided by the second satellite, setting the scaling factor to be equal to 1.

[0009] According to a fourth embodiment of the first aspect, said any communication opportunity of the serving cell currently usable by the apparatus comprises a downlink opportunity of the serving cell when the apparatus is operating in an idle or inactive mode.

[0010] According to a fifth embodiment of the first aspect, said any communication opportunity of the serving cell currently usable by the apparatus comprises, when the apparatus is operating in an idle or inactive mode:a downlink opportunity of the serving cell if no random access channel, RACH, procedure is on-going at the apparatus, ordownlink and uplink opportunities of the serving cell if a RACH procedure is ongoing at the apparatus.

[0011] According to a sixth embodiment of the first aspect, said any communication opportunity of the serving cell currently usable by the apparatus comprises both downlink and uplink opportunities of the serving cell when the apparatus is operating in a connected mode.

[0012] According to a seventh embodiment of the first aspect, the at least one memory and the instructions are configured, with the at least one processor, to cause the apparatus to perform:receiving, from the first satellite via the serving cell, neighbor cell information for one or more neighbor cells of the serving cell being provided by one or more satellites, wherein the neighbor cell information defines at least one or more downlink opportunities of the one or more neighbor cells; anddetermining, based at least on the neighbor cell information, whether the serving cell has the neighbor cell provided by the second satellite,wherein the determining whether the downlink opportunity of the neighbor cell overlaps with said any communication opportunity of the serving cell currently usable by the apparatus is based at least on the neighbor cell information.

[0013] According to an eighth embodiment of the first aspect, the neighbor cell is an intra-frequency neighbor cell.

[0014] According to a ninth embodiment of the first aspect, the at least one memory and the instructions are configured, with the at least one processor, to cause the apparatus to execute the cell reselection process using the scaling factor.

[0015] According to a tenth embodiment of the first aspect, further defining the ninth embodiment, the executing of the cell reselection process comprises:performing narrowband reference signal received power, NRSRP, measurements of any intra-frequency neighbor cell at least every Ksateiiite *Tmeasure,NB_intra_NC, wherein Ksateiiite is the scaling factor, and Tmeasure,NB_intra_NC is a pre-defined time reserved for measuring of an intra-frequency cell.

[0016] According to an eleventh embodiment of the first aspect, further defining the ninth embodiment, the executing of the cell reselection process comprises:evaluating whether a detectable intra-frequency cell meets one or more predefined reselection criteria within KSateiiite*Tdetect,NB_intra, wherein Ksateiiite is the scaling factor, and Tdetect,NB intra NC is a pre-defined time reserved for detection of a new intra-frequency cell before evaluating it for cell reselection.

[0017] According to a twelfth embodiment of the first aspect, further defining the ninth embodiment, the executing of the cell reselection process comprises:evaluating whether a detected intra-frequency cell meets one or more pre-defined reselection criteria within Ksateiiite *Tevaiuate,NB_intra-NC, wherein Ksateiiite is the scaling factor, and Tevaiuate.NB intra-Nc is a pre-defined time reserved for evaluating a detected intra-frequency cell for cell reselection.

[0018] According to a thirteenth embodiment of the first aspect, the serving cell and the neighbor cell employ time domain duplexing, TDD, for communication with the apparatus.

[0019] According to a fourteenth embodiment of the first aspect, further defning the thirteenth embodiment, the serving cell and the neighbor cell employ a TDD frame structure comprising a n downlink subframes and n uplink subframes, the n downlink subframe and n uplink subframes being paired one-to-one to form n uplink-downlink subframe pairs, and one uplink-downlink subframe pair, defining uplink and downlink opportunities, being active at any given time, n being a positive integer.

[0020] According to a fifteenth embodiment of the first aspect, the first satellite is a first low-Earth orbit, LEO, satellite or a first non-geostationary orbit, NGSO, satellite, and the second satellite is a second LEO satellite or a second NGSO satellite.

[0021] According to a sixteenth embodiment of the first aspect, the apparatus is a Narrowband Internet of Things user equipment, NB-IoT UE.

[0022] According to a second aspect, there is provided a non-transitory computer readable medium having stored thereon instructions that, when executed by a computing device, cause the computing device to perform:determining whether a serving cell of the computing device, being provided by a first satellite, has a neighbor cell provided by a second satellite; andbased on the serving cell of the computing device having a neighbor cell provided by the second satellite,- determining whether a downlink opportunity of the neighbor cell overlaps with any communication opportunity of the serving cell currently usable by the computing device, and- based on the downlink opportunity of the neighbor cell overlapping with no communication opportunity of the serving cell currently usable by the computing device, setting a scaling factor for a cell reselection process involving one or more satellites to be equal to 1, wherein the scaling factor is usable, at the apparatus, for scaling timing of least one of cell detection, cell measurements or cell evaluation for cell reselection.

[0023] According to a third aspect, there is provided a method comprising:determining whether a serving cell of an apparatus, being provided by a first satellite, has a neighbor cell provided by a second satellite; andbased on the serving cell of the apparatus having a neighbor cell provided by the second satellite,- determining whether a downlink opportunity of the neighbor cell overlaps with any communication opportunity of the serving cell currently usable by the apparatus, and - based on the downlink opportunity of the neighbor cell overlapping with no communication opportunity of the serving cell currently usable by the apparatus, setting a scaling factor for a cell reselection process involving one or more satellites to be equal to 1, wherein the scaling factor is usable, at the apparatus, for scaling timing of least one of: cell detection, cell measurements or cell evaluation for cell reselection.

[0024] According to a first embodiment of the third aspect, the method further comprises, based on the serving cell having the neighbor cell provided by the second satellite,- based on the downlink opportunity of the neighbor cell overlapping with a communication opportunity of the serving cell currently usable by the apparatus, setting the scaling factor to be equal to 2

[0025] According to a second embodiment of the third aspect, the neighbor cell is a first neighbor cell, and the method further comprises:based on the downlink opportunity of the first neighbor cell not overlapping with any communication opportunity of the serving cell currently usable by the apparatus,- determining whether the serving cell has a second neighbor cell provided by a third satellite and having no downlink opportunity overlapping with said any communication opportunity of the serving cell;- based on the serving cell having the second neighbor cell provided by the third satellite and having no downlink opportunity overlapping with said any communication opportunity of the serving cell, enabling radio measurements of the second neighbor cell, in addition to the serving cell and the first neighbor cell, and setting the scaling factor to be equal to 2

[0026] According to a third embodiment of the third aspect, the method further comprises:based on the serving cell having no neighbor cell provided by the second satellite, setting the scaling factor to be equal to 1.

[0027] According to a fourth embodiment of the third aspect, said any communication opportunity of the serving cell currently usable by the apparatus comprises a downlink opportunity of the serving cell when the apparatus is operating in an idle or inactive mode.

[0028] According to a fifth embodiment of the third aspect, said any communication opportunity of the serving cell currently usable by the apparatus comprises, when the apparatus is operating in an idle or inactive mode:a downlink opportunity of the serving cell if no random access channel, RACH, procedure is on-going at the apparatus, ordownlink and uplink opportunities of the serving cell if a RACH procedure is ongoing at the apparatus.

[0029] According to a sixth embodiment of the third aspect, said any communication opportunity of the serving cell currently usable by the apparatus comprises both downlink and uplink opportunities of the serving cell when the apparatus is operating in a connected mode.

[0030] According to a seventh embodiment of the third aspect, the method further comprises:receiving, from the first satellite via the serving cell, neighbor cell information for one or more neighbor cells of the serving cell being provided by one or more satellites, wherein the neighbor cell information defines at least one or more downlink opportunities of the one or more neighbor cells; anddetermining, based at least on the neighbor cell information, whether the serving cell has the neighbor cell provided by the second satellite,wherein the determining whether the downlink opportunity of the neighbor cell overlaps with said any communication opportunity of the serving cell currently usable by the apparatus is based at least on the neighbor cell information.

[0031] According to an eighth embodiment of the third aspect, the neighbor cell is an intra-frequency neighbor cell.

[0032] According to a ninth embodiment of the third aspect, the method further comprises executing the cell reselection process using the scaling factor.

[0033] According to a tenth embodiment of the third aspect, further defining the ninth embodiment, the executing of the cell reselection process comprises:performing narrowband reference signal received power, NRSRP, measurements of any intra-frequency neighbor cell at least every Ksateiiite *Tmeasure,NB_intra_NC, wherein Ksateiiite is the scaling factor, and Tmeasure,NB_intra_NC is a pre-defined time reserved for measuring of an intra-frequency cell.

[0034] According to an eleventh embodiment of the third aspect, further defining the ninth embodiment, the executing of the cell reselection process comprises:evaluating whether a detectable intra-frequency cell meets one or more predefined reselection criteria within KSateiiite*Tdetect,NB_intra, wherein Ksateiiite is the scaling factor, and Tdetect,NB intra NC is a pre-defined time reserved for detection of a new intra-frequency cell before evaluating it for cell reselection.

[0035] According to a twelfth embodiment of the third aspect, further defining the ninth embodiment, the executing of the cell reselection process comprises:evaluating whether a detected intra-frequency cell meets one or or more predefined reselection criteria within KSateiiite*Tevaiuate,NB_intra-NC, wherein Ksateiiite is the scaling factor, and Tevaiuate.NB intra-Nc is a pre-defined time reserved for evaluating a detected intra-frequency cell for cell reselection.

[0036] According to a thirteenth embodiment of the third aspect, the serving cell and the neighbor cell employ time division duplexing, TDD, for communication with the apparatus.

[0037] According to a fourteenth embodiment of the third aspect, further defining the thirteenth embodiment, the serving cell and the neighbor cell employ a TDD frame structure comprising a n downlink subframes and n uplink subframes, the n downlink subframe and n uplink subframes being paired one-to-one to form n uplink-downlink subframe pairs, and one uplink-downlink subframe pair, defining uplink and downlink opportunities, being active at any given time, n being a positive integer.

[0038] According to a fifteenth embodiment of the third aspect, the first satellite is a first low-Earth orbit, LEO, satellite or a first non-geostationary orbit, NGSO, satellite, and the second satellite is a second LEO satellite or a second NGSO satellite.

[0039] According to a sixteenth embodiment of the third aspect, the method is performed by a Narrowband Internet of Things user equipment, NB-IoT UE.

[0040] According to a fourth aspect, there is provided an apparatus comprising:at least one processor; andat least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform:based on a serving cell of the apparatus, being provided by a first satellite, having a first neighbor cell provided by a second satellite,- determining whether a downlink opportunity of the first neighbor cell overlaps with any communication opportunity of the serving cell currently usable by the apparatus, and - based on the downlink opportunity of the first neighbor cell not overlapping with said any communication opportunity of the serving cell currently usable by the apparatus,• determining whether a downlink opportunity of a second neighbor cell, provided by a third satellite, overlaps with the downlink opportunity of the first neighbor cell; and• based on the downlink opportunity of the second neighbor cell not overlapping with the downlink opportunity of the first neighbor cell, setting a scaling factor for a cell reselection process involving one or more satellites to be equal to 1, wherein the scaling factor is usable, at the apparatus, for scaling timing of least one of: cell detection, cell measurements or cell evaluation for cell reselection.

[0041] According to a first embodiment of the fourth aspect, the at least one memory and the instructions are configured, with the at least one processor, to cause the apparatus to perform, based on the serving cell having the first neighbor cell provided by the second satellite,- based on the downlink opportunity of the first neighbor cell overlapping with said any communication opportunity of the serving cell currently usable by the apparatus, setting the scaling factor to be equal to 2.

[0042] According to a second embodiment of the fourth aspect, the at least one memory and the instructions are configured, with the at least one processor, to cause the apparatus to perform, based on the downlink opportunity of the first neighbor cell not overlapping with said any communication opportunity of the serving cell currently usable by the apparatus,• based on the downlink opportunity of the second neighbor cell overlapping with the downlink opportunity of the first neighbor cell, setting the scaling factor to be equal to 2.

[0043] According to a third embodiment of the fourth aspect, the at least one memory and the instructions are configured, with the at least one processor, to cause the apparatus to perform, based on the downlink opportunity of the first neighbor cell not overlapping with said any communication opportunity of the serving cell currently usable by the apparatus,• based on the downlink measurement opportunity of the second neighbor cell overlapping with the downlink opportunity of the first neighbor cell while not overlapping with said any communication opportunity of the serving cell currently usable by the apparatus, enabling radio measurements of the second neighbor cell, in addition to the serving cell and the first neighbor cell, and setting the scaling factor to be equal to 2; and• based on the downlink measurement opportunity of the second neighbor cell overlapping with the downlink opportunity of the first neighbor cell and also with said anycommunication opportunity of the serving cell currently usable by the apparatus, setting the scaling factor to be equal to 2

[0044] According to a fourth embodiment of the fourth aspect, the at least one memory and the instructions are configured, with the at least one processor, to cause the apparatus to perform:based on the serving cell having no neighbor cell provided by the second satellite, setting the scaling factor to be equal to 1.

[0045] According to a fifth embodiment of the fourth aspect, said any communication opportunity of the serving cell currently usable by the apparatus comprises a downlink opportunity of the serving cell when the apparatus is operating in an idle or inactive mode.

[0046] According to a sixth embodiment of the fourth aspect, said any communication opportunity of the serving cell currently usable by the apparatus comprises, when the apparatus is operating in an idle or inactive mode:a downlink opportunity of the serving cell if no random access channel, RACH, procedure is on-going at the apparatus, ordownlink and uplink opportunities of the serving cell if a RACH procedure is ongoing at the apparatus.

[0047] According to a seventh embodiment of the fourth aspect, said any communication opportunity of the serving cell currently usable by the apparatus comprises both downlink and uplink opportunities of the serving cell when the apparatus is operating in a connected mode.

[0048] According to an eighth embodiment of the fourth aspect, the at least one memory and the instructions are configured, with the at least one processor, to cause the apparatus to perform:receiving, from the first satellite via the serving cell, neighbor cell information for one or more neighbor cells of the serving cell being provided by one or more satellites, wherein the neighbor cell information defines at least one or more downlink opportunities of the one or more neighbor cells; anddetermining, based at least on the neighbor cell information, whether the serving cell has the neighbor cell provided by the second satellite,wherein the determining whether the downlink opportunity of the first neighbor cell overlaps with said any communication opportunity of the serving cell currently usable bythe apparatus and the determining whether the downlink opportunity of the second neighbor cell, overlaps with the downlink opportunity of the first neighbor cell are based at least on the neighbor cell information.

[0049] According to an ninth embodiment of the fourth aspect, the first and second neighbor cells are an intra-frequency neighbor cells.

[0050] According to a tenth embodiment of the fourth aspect, the at least one memory and the instructions are configured, with the at least one processor, to cause the apparatus to execute the cell reselection process using the scaling factor.

[0051] According to a eleventh embodiment of the fourth aspect, further defining the tenth embodiment, the executing of the cell reselection process comprises:performing narrowband reference signal received power, NRSRP, measurements of any intra-frequency neighbor cell at least every Ksateiiite *Tmeasure,NB_intra_NC, wherein Ksateiiite is the scaling factor, and Tmeasure,NB_intra_NC is a pre-defined time reserved for measuring of an intra-frequency cell

[0052] According to a twelfth embodiment of the fourth aspect, further defining the tenth embodiment, the executing of the cell reselection process comprises:evaluating whether a detectable intra-frequency cell meets one or more predefined reselection criteria within KSateiiite*Tdetect,NB_intra, wherein Ksateiiite is the scaling factor, and Tdetect,NB intra NC is a pre-defined time reserved for detection of a new intra-frequency cell before evaluating it for cell reselection.

[0053] According to a thirteenth embodiment of the fourth aspect, the executing of the cell reselection process comprises:evaluating whether a detected intra-frequency cell meets one or more pre-defined reselection criteria within Ksateiiite *Tevaiuate,NB_intra-NC, wherein Ksateiiite is the scaling factor, and Tevaiuate.NB intra-Nc is a pre-defined time reserved for evaluating a detected intra-frequency cell for cell reselection.

[0054] According to a fourteenth embodiment of the fourth aspect, the serving cell and the first and second neighbor cells employ time division duplexing, TDD, for communication with the apparatus.

[0055] According to a fifteenth embodiment of the fourth aspect, further defining the fourteenth embodiment, the serving cell, the first neighbor cell and the second neighbor cell employ a TDD frame structure comprising a n downlink subframes and n uplink subframes, the n downlink subframes and n uplink subframes being paired one-to-one to form n uplinkdownlink subframe pairs, and one uplink-downlink subframe pair, defining uplink and downlink opportunities, being active at any given time, n being a positive integer.

[0056] According to a sixteenth embodiment of the fourth aspect, the first satellite is a first low-Earth orbit, LEO, satellite or a first non-geostationary orbit, NGSO, satellite, and the second satellite is a second LEO satellite or a second NGSO satellite, and the third satellite is a third LEO satellite or a third NGSO satellite.

[0057] According to a seventeenth embodiment of the fourth aspect, the apparatus is a Narrowband Internet of Things user equipment, NB-IoT UE.BRIEF DESCRIPTION OF THE DRAWINGS

[0058] FIG. 1 illustrates an example of a network scenario in accordance with at least some example embodiments;

[0059] FIG. 2 illustrates a time division duplexing (TDD) frame structure usable in embodiments;

[0060] FIG. 3 illustrates two overlapping TDD frame structure associated with a serving cell and its neighbor cell usable in embodiments;

[0061] FIGs. 4 to 7 illustrate processes according to some embodiments; and

[0062] FIG. 8 illustrates an apparatus according to some embodiments.DETAILED DESCRIPTION OF SOME EMBODIMENTS

[0063] Embodiments of the present disclosure provide enhancements for timing of mobility measurements in Non-Terrestrial Networks (NTNs). More specifically, at least some embodiments may pertain to enhancements for timing of mobility measurements in NTNs employing a time division duplexing (TDD) pattern (i.e., a TDD frame structure). The timing of the mobility measurements may be adjusted, in embodiments, at least by adjustment of ascaling factor Ksateiiite for scaling, at the apparatus, timing of cell detection, cell measurements and / or cell evaluation associated with a cell reselection process.

[0064] FIG. 1 illustrates an example of a network scenario in accordance with at least some example embodiments. Illustrated is user equipment (UE) 110 (equally called a user terminal, a user device or a terminal device). The UE 110 may be, for example, a Narrowband Internet of Thing (NB-IoT) device, a Machine-Type Communication (MTC) device, Internet of Things (loT) device, a 5G New Radio Reduced Capability (RedCap) device, an enhanced RedCap (eRedCap) device. In other embodiments, the UE 110 may be a smartphone, a feature phone, a tablet computer, a laptop computer, a desktop computer or a smartwatch, or a vehicle, for example. For example, NB-IoT device can be embedded in a smartphone. An example use case of a NB-IoT device is animal tracking. The UE 110 may be a half-duplex device, which cannot receive and transmit simultaneously.

[0065] The UE 110 may be an NTN UE or a dual-capability UE. The dual-capability UE may be defined as a UE which is capable of both NTN communication as well as terrestrial network communication (e.g., communication in terrestrial cellular and / or non-cellular systems or networks). Examples of terrestrial cellular systems include Long Term Evolution (LTE), fifth generation (5G), also known as New Radio (NR), and sixth generation (6G). Examples of terrestrial non-cellular systems include Wireless Local Area Network (WLAN) and Worldwide interoperability for Microwave Access (WiMAX).

[0066] UE 110 may be furnished with a satellite navigation capability, for example in the form of a satellite navigation receiver installed in the UE 110, and be configured to receive signals from a navigation satellite constellation, such as Global Positioning System (GPS) and / or the Galileo constellation. A satellite navigation capability may be used to determine the location and / or current time at the UE 110. The satellite navigation satellite constellation may be distinct from an NTN satellite constellation that the UE 110 may be configured to use for communication. Satellite links and NTN communications may be used at least to provide cellular communications to UEs on remote areas, disaster zones or over the sea.

[0067] In some embodiments, the UE 110 may be, in particular, a narrowband loT (NB-loT) device. NB-IoT device may be defined as a UE capable of communicating with an NB-loT network. The NB-IoT device is characterized by having a low power consumption, wide coverage and using a narrow frequency bandwidth. In some embodiments, the transmit power of the NB-IoT device may be equal to or smaller than 23 dBm. Additionally or alternatively,said narrow frequency bandwidth of the NB-IoT device may be defined to be equal to or smaller than 180 kHz. The NB-IoT device as used in embodiments may belong to one of two NB-IoT categories: Category NB1 (having lower complexity) and Category NB2 (enabling support for higher data rates and additional features). Category NB1 and Category NB2 are defined, respectively, in 3GPP Releases 13 & 14. Examples of NB-IoT devices may comprise a smart meter, an environmental sensor or a wearable device.

[0068] Service link 112 may connect the UE 110 with a non-terrestrial wireless network node 120. Non-terrestrial wireless network node 120 may be referred to as a satellite, configured to perform non-terrestrial communications with UE 110 over service link 112. Non-terrestrial wireless network node 120 may be in orbit 101 about the Earth, for example in Geostationary Earth Orbit, GEO, or Low-Earth Orbit, LEO. A GEO orbit may be defined as an orbit located at approximately 36000 km from Earth, above the equator. The orbit period of GEO satellites may be equivalent to one astronomical day. Therefore, GEO satellites may be static from the point of view of one user, or UE 110, on Earth. The GEO satellites have been around for decades and mostly used for low throughput applications. Recent technical developments have made the GEO deployments significantly attractive for new medium and high throughput applications using satellites.

[0069] LEO orbit may be defined as an orbit located at heights between 300 km and 1500 km above Earth. LEO satellites may be deployed in different orbit inclinations and orientations around Earth, and travel and significant speeds (approximately 7500 m / s at 600 km) and have a very high relative speed from an observer on Earth, such as the UE 110.

[0070] Some embodiments may involve, in particular, non-terrestrial wireless network nodes 120 being LEO satellites. In some such embodiments, the LEO satellites (or at least some of them) may have an altitude of 600 km or 1200 km with earth-fixed and / or earth -moving cells in the 1616-1626.5 MHz mobile-satellite services (MSS) band.

[0071] In case of a regenerative architecture, lower layers may be implemented at the hardware located in non-terrestrial wireless network node 120, meaning that some central functions deployed by a Base Station (BS) may be deployed at non-terrestrial wireless network node 120, such as scheduling, retransmissions and / or random access. A BS may be equally called an access node or an access point or a network node. In case of transparent architecture, hardware of non-terrestrial wireless network node 120 may act simply as a repeater or frequency converter, for a BS located on a ground station, such as BS 134, and the latency of thescheduling algorithms may be twice as high as in the case of regenerative architecture. In some example embodiments, non-terrestrial wireless network node 120 may be a transparent relay, meaning that non-terrestrial wireless network node 120 may act as an amplify-and-forward type of relay between UE 110 and a non-terrestrial gateway (NTN-GW) 130 on the Earth’s surface.

[0072] In some example embodiments, the non-terrestrial wireless network node 120 may be referred to as a BS. For example, in the context of LTE, the non-terrestrial wireless network node 120 may be referred to as an eNB while the non-terrestrial wireless network node 120 may be referred to as a gNB in the context of NR. In any case, example embodiments are not restricted to any particular wireless technology. Instead, example embodiments may be exploited in any cellular communication network wherein non-terrestrial communications are used, such as in 6G networks. Non-terrestrial wireless network node 120 may be solar-powered or powered by heat from radioactive decay, for example. The satellite’s orbit 101 is, in part, schematically denoted in FIG. 1, as is its momentary orbital velocity vector 120v. The service link 112 may convey information in the downlink, from the non-terrestrial wireless network node 120 to the UE 110, and in the uplink from the UE 110 to the non-terrestrial wireless network node 120.

[0073] The non-terrestrial wireless network node 120 may have a feeder link 123 with the NTN-GW 130. As is the case with the service link 112, the feeder link 123 may convey information in both directions, uplink and downlink. The service link 112 and the feeder link 123 may be wireless links, but they need not comply with the same wireless technology. However, in some embodiments, the service link 112 and the feeder link 123 may be based on the same wireless technology. The NTN-GW 130 may comprise the BS 134, or it may be arranged in connection with the BS 134, wherefore the UE 110 may access an NTN cellular system via the non-terrestrial wireless network node 120 such that the non-terrestrial wireless network node 120 may act as the bidirectional relay between the UE 110 and the NTN-GW 130.

[0074] One terrestrial BS 134 may control one or more cells, and communicate with the UE 110 over air interface 113. In some embodiments, the BS 134 may have an interface with the NTN-GW 130 or core network 140. The NTN-GW 130 may be connected with further nodes via another gateway or core network 140, for example.

[0075] While the non-terrestrial wireless network node 120 and the UE 110 may be a mobile, non-terrestrial wireless network node 120 moving at a high speed, the NTN-GW 130may be a stationary node. When a constellation of satellite 120 is employed, the UE 110 may in principle be almost anywhere, or indeed anywhere, on the Earth’s surface. Compared to terrestrial cellular systems, NTN cellular systems may need enhanced timing corrections. Such enhancements are more central in NTN systems due to the long propagation distance, and delay, between the UE 110 and the non-terrestrial wireless network node 120 over the service link 112, but also due to the fast movement of the non-terrestrial wireless network node 120 which causes Doppler shifts. Furthermore, in transparent satellites, there is an additional time delay and frequency shift due to the feeder link 123 between NTN-GW 130 and non-terrestrial wireless network node 120.

[0076] Said satellites usable in NTNs may comprise, for example, low Earth orbit (LEO) satellites which may reach speeds of up to 7600 m / s. This presents challenges for the operation of the NTN as user equipment (UE) can only measure the radio signals transmitted by such LEO satellites for a limited amount of time before the satellite disappears beyond the horizon or the cell is switched away. Moreover, in LEO scenarios, the relative speed of the satellite imposes significant Doppler offsets which need to be post compensated by the UEs in downlink. Recently, adoption of Internet of Things (loT) time division duplexing (TDD) in narrowband Internet of Things (NB-IoT) in NTNs has been suggested. Said problems need to be addressed in the implementation of said loT TDD for NB-IoT

[0077] Compared to a purely terrestrial cellular communication systems, there are multiple challenges to be addressed in order to provide NTN coverage in a system natively designed to provide terrestrial coverage. One such challenge relates to the aforementioned high speeds of the LEO satellites. Due to said high speeds, a UE can only measure radio signals transmitted by such a LEO satellite for a limited amount of time before the satellite disappears on the horizon or the cell is switched away. Moreover, the high speed of the LEO satellites imposes significant doppler offsets which need to be post-compensated by the UEs in downlink. This fact needs to be taken into account, e.g., in cell reselection procedures used in NTNs. Namely, in the cell reselection requirements, the total time for the UE to complete the measurements may be scaled by a scaling factor called Ksateiiite. Said scaling factor may also be used for scaling of timing in cell detection and cell evaluation subprocesses of the cell reselection process.

[0078] In order to provide context for embodiments to be discussed below which pertain to adjustment of the scaling factor Ksateiiite, the definition and use of the scaling factor Ksateiiite isdiscussed the following. It is noted that the scaling factor Ksateiiite is defined, in general, according to 3GPP standards, namely at least 3GPP TS 36.133 and 36.306.

[0079] According to a conventional definition derived from 3GPP TS 36.133, the scaling factor Ksateiiite is a scaling factor for measurement timing at a UE for measurements corresponding to one or more non-geostationary orbit (NGSO) satellites (e.g., one or more LEO satellites). If a geostationary orbit (GSO) satellite(s) is / are measured on the carrier or if there is only one NGSO satellite associated to cells the UE is required to monitor (or measure), Ksateiiite may be equal to 1. If multiple NGSO satellites are to be monitored (or measured), Ksateiiite may be equal to the number NGSO satellites to be measured. Typically, the maximum number of NGSO satellites which may be monitored by a single UE is 2 (and, thus, the value of Ksateiiite is limited to 2). The scaling factor may be defined per frequency layer (i.e., per frequency band), as defined in 3GPP TS 36.306. The embodiments to be discussed to be discussed seek to amend this definition to accommodate use of time-domain duplexing (as opposed frequency domain duplexing). Namely, in connection with embodiments, if there are two or more satellites, e.g. NGSO satellites, associated to the cells the UE is required to measure, the scaling factor Ksateiiite may be 1 or 2 depending on overlap of communication opportunities associated with said two or more (NGSO) satellites, as will be discussed in detail below.

[0080] The scaling factor Ksateiiite affects how measurements of intra-frequency NB-IoT cells (at least for UE category NB1) in normal coverage are carried out. The UE may be able to identify new intra-frequency cells and perform narrowband reference signal received power (NRSRP) measurements of identified intra-frequency cells without an explicit intra-frequency neighbor list containing physical layer cell identities. The UE may be able to evaluate whether a (newly) detectable intra-frequency cell meets (one or more) pre-defined reselection criteria defined in TS36.304 within Ksateiiite *Tdetect,NBjntra_NC when Treselection= 0, where Tdetect,NB intra NC is a (pre-defined) time reserved for detection of a new intra-frequency cell before evaluating it for (cell) reselection (i.e., a time to detect a cell) and Treselection is a (cell) reselection timer. An intra frequency cell may be considered to be detectable according to any of NRSRP, NRSRP Es / Iot, NSCH RP and NSCH Es / Iot defined in Annex B.1.4 of 3GPP TS 36.133 for a corresponding Band. Here, NSCH denotes a narrowband shared channel, Es / Iot is signal-to-inteference-plus-noise (SINR) metric used in NB-IoT and RP is received power.

[0081] Moreover, the UE may measure NRSRP at least every KSateiiite*Tmeasure,NBjntra_NC at least for intra-frequency cells that are identified and measured according to the measurementrules, where Tmeasure,NBjntra_NC is a (pre-defined) time reserved for measuring of an intrafrequency cell (i.e., a time to measure a cell).

[0082] The UE may filter NRSRP measurements of each measured intra-frequency cell using at least 2 measurements. Within the set of measurements used for the filtering, at least two measurements may be spaced by at least Tmeasure,NBjntra-Nc / 2.

[0083] For an intra-frequency cell that has been already detected, but that has not been reselected to, the filtering may be such that the UE may be capable of evaluating that the (detected) intra-frequency cell has met reselection criteria defined, e.g., in 3GPP TS 36.304 within Ksateiiite * Tevaiuate,NB intra-Nc when Treseiection = 0, provided that the (detected) intra-frequency cell is at least X dB better ranked (compared to the serving cell), where ‘X’ is a cell reselection margin which may be defined, e.g., as specified in Table 4.6A.2.4-3 of 3GPP TS 36.133 and Tevaiuate.NB intra-Nc is a (pre-defined) time reserved for evaluating a detected intra-frequency cell for (cell) reselection (i.e., a time to evaluate a cell). When evaluating cells for reselection, the side conditions for NRSRP, NRSRP Es / Iot, NSCH RP and NSCH Es / Iot apply to both serving and non-serving NB-IoT intra-frequency cells. For example, said reselection criteria may comprise at least one of a criterion requiring that signal quality (or strength) of a serving cell is below a first predefined threshold, a criterion requiring that signal quality (or strength) of a neighbor cell is above a second pre-defined threshold, suggesting it can offer better service than the current cell, a criterion relating to priority levels assigned to serving and / or neighbor cells or a criterion based on ranking of (neighbor) cells according to their signal quality measurements.

[0084] The scaling factor Ksateiiite may also have an effect on inter-frequency neighbor cell measurements, as defined in 3GPP TS 36.206 (namely, in Section 8.14A.6.4 thereof). Namely, the UE may be able to identify a new detectable inter-frequency cell within Tidentify inter NBi-Nc,m when pre-defined criteria for inter-frequency measurement, as defined in, is fulfilled, where Tidentify inter _NBi-Nc,m is dependent on, among other parameters, on Ksatellite m(i.e., on the scaling factor Ksatellitedefined for frequency layer of index m).

[0085] As indicated above, adoption of Internet of Things (loT) time division duplexing (TDD) in narrowband Internet of Things (NB-IoT) systems in NTNs has been suggested, instead of previously used frequency domain duplexing (FDD). In at least some embodiments, the (LEO or NGSO) satellites may be assumed to employ TDD. FIG. 2 illustrates one exemplary TDD frame structure 200 (or TDD pattern) usable in connection with embodiments.

[0086] Referring to FIG. 2, the TDD frame structure 200 comprises a simplex time slot 201, a 4 uplink subframes 202 to 205 and 4 downlink subframes 206 to 209. The 4 uplink subframes 202 to 205 and 4 downlink subframes 206 to 209 are paired one-to-one to form 4 uplink-downlink subframe pairs (i.e., pairs ULI & DL1, UL2 & DL2, UL3 & DL3 and UL4 & DL4). In one example, each cell will operate exclusively with one uplink-downlink pair, for example pairs ULI & DL1, while another cell may operate with another or the same uplinkdownlink pair. The simplex time slot and each uplink and downlink subframe may be preceded by a (fixed or adjustable) guard period (depicted in FIG. 2 as black blocks). One uplinkdownlink subframe pair, defining uplink and downlink opportunities, may be active at any given time. In other words, the active uplink and downlink subframes may always have the same index in the TDD frame structure 200. Each uplink-downlink subframe pair defines uplink and downlink opportunities (i.e., time windows during which uplink and downlink communication can be carried out). In the illustrated example, the simplex time slot 201 has a duration of 20.32 ms, the uplink and downlink subframes 202 to 209 have, each, a duration of 8.28 ms, and the total duration of the TDD frame structure 200 is 90 ms. The guard period 201 may be fixed or adjustable.

[0087] As implied above, a UE when receiving a scheduling grant in DL1 subframe will have to transmit in ULI subframe. Likewise, UL2, UL3 and UL4 are paired to different cells and UEs in the area of coverage of the satellite. This means that, if the UE is transmitting on ULI, it is not expected to transmit in any of the other UL opportunities within the 90 ms TDD pattern 200 and is only expected to receive information, from the serving cell to which the UE can transmit, during DLL In one example, this results in the UE being able to receive information from the serving cell in 8 ms (or 8.28 ms) every 90 ms. As is visible in FIG. 2, the separation between a downlink opportunity and the paired uplink opportunity is 3*8.28 ms + 3 guard periods + the simplex time slot and thus at least 45 ms

[0088] More generally, the TDD frame structure usable in embodiments may comprise n downlink subframes and n uplink subframes, where the n downlink subframes and n uplink subframes are paired one-to-one to form n uplink-downlink subframe pairs. Here, n is a positive integer. The n downlink subframes and n uplink subframes may be arranged, e.g., similar to the example of FIG. 2, that is, the n uplink subframes may precede the n downlink subframes (or vice versa). A (fixed or adjustable) guard period may precede each uplink and downlink subframe. Additionally, the TDD frame structure may comprise a simplex time slot (and its guard period) arranged in the beginning of the TDD frame structure, similar to FIG. 2.Moreover, the specific time values indicated in FIG. 2 should be considered exemplary values. Thus, the durations of the different subframes / slots and the total duration of the TDD frame structure may differ from the ones shown in FIG. 2, in some embodiments.

[0089] As discussed above in detail, the scaling factor Ksateiiite for measurement timing was introduced in 3GPP TS 36.133 to account for the fact that, because of the significant Doppler difference between serving and target satellites to be measured, the UE can either measure one or the other but not both. This leads to “shared” communication opportunities. To account for the splitting of the downlink (measurement) opportunities, it makes sense to expand the time to detect (and to measure, and to evaluate) a cell using the scaling factor Ksateiiite.

[0090] The above consideration was based on use of FDD in the NTN. However, when using the TDD frame pattern 200 as discussed in connection with FIG. 2, said splitting of the downlink (measurement) opportunities no longer happens if the cells to be measured belong to non-overlapping downlink transmission opportunities (that is, non-overlapping in time domain). For example, if UE is receiving from the serving cell in DL1, the UE can perform downlink measurements on other cells for the remainder of the periodic TDD frame except for ULI, i.e. in one or more of DL2, DL3, DL4, UL2, UL3, UL4 and the simplex slot. Hence, the serving cell DL1 downlink measurement opportunity may not be overlapping with neighbor cells using for example DL2, DL3, or DL4.

[0091] To illustrate the discussed in the previous paragraph, FIG. 3 shows two TDD frame patterns 301, 302 as observed by a particular UE. The first TDD frame pattern 301 corresponds to a TDD frame pattern of a serving cell provided by a serving satellite (e.g., a serving LEO or NGSO satellite), and the second TDD frame pattern 302 corresponds to a TDD frame pattern of a neighbor cell of the serving cell provided by a neighbor satellite (e.g., a neighbor LEO or NGSO satellite). Said first and second TDD frame patterns 301, 302 have the same structure as the TDD frame pattern 200 of FIG. 2. The second TDD frame pattern 302 is shifted in time relative to the first TDD frame pattern 301 due to the propagation delay difference between the propagation paths between the UE and the serving satellite and between the UE and the neighbor satellite.

[0092] Now, if we consider the scenario of FIG. 2 in case where the UE is allocated to DL1 & ULI subframes on the serving satellite while also being enabled to employ UL2 & DL 2 of the neighbor satellite. Notably, there is no overlap between said subframes from the point of view of the UE. Therefore, it would make no sense to set the scaling factor Ksateiiite to beequal to 2 in this particular case even though the UE is required to measure two separate satellites. The embodiments seek to overcome this issue by introducing additional processes for setting the value of the scaling factor Ksateiiite. For example, a technical advantage will be that by reducing the Ksateiiite to be equal to 1 the measurements can be completed faster.

[0093] FIG. 4 illustrates a process for setting value of a scaling factor (e.g., Ksateiiite) for timing of one or more actions relating to cell reselection according to embodiments. The process of FIG. 4 may be carried out by an apparatus. The apparatus may be a UE, such as a UE 110 of FIG. 1, or a part thereof. In some embodiments, the apparatus may be an NB-IoT UE (e.g., an NB-IoT device of category NB1). In the following, the entity carrying out the process of FIG.4 is called simply an apparatus.

[0094] Referring to FIG. 4, it is initially evaluated, in block 401, whether a (current) serving cell, provided by a first satellite, has a neighbor cell provided by a second satellite. Here, the first and second satellites may be, e.g., LEO or NGSO satellites. The first and second satellites may be employ TDD for communication with the apparatus (or, in general, with any UEs). The first and second satellites may, e.g., employ the TDD frame pattern 200 of FIG. 2. In some embodiments, the neighbor cell provided by the second satellite may be an intrafrequency (neighbor) cell (i.e., a cell operating at the same carrier frequency as the serving cell) or an NB-IoT intra-frequency (neighbor) cell. The evaluation of block 401 may be based on neighbor cell information (comprising, e.g., information on downlink and uplink occasions of one or more neighbor cells of the serving cell) obtained from the serving cell, as will be described in further detail in connection with FIG. 5.

[0095] Based on the serving cell having a neighbor cell provided by a second satellite in block 401, the apparatus carried out actions of blocks 402, 403, 404 or blocks 402, 403, 405. Namely, the apparatus determines, in block 402, whether a downlink opportunity (i.e., a downlink measurement opportunity) of the neighbor cell overlaps with any communication opportunity of the serving cell currently usable (or used) by the apparatus. Here and in the following, the term “communication opportunity” is defined as a general term for an opportunity which may be either a downlink opportunity or an uplink opportunity. A downlink opportunity is defined as a periodically repeated downlink subframe during which the associated cell is expected to be transmitting. An uplink opportunity is defined as a periodically repeated uplink subframe during which the UE(s) are expected to be transmitting. The downlink / uplink transmission may not be allowed outside of the downlink / uplink opportunity,for example because the satellite is operating in TDD mode. The overlapping may refer, here and in the following features relating to overlapping of any communication opportunities, to overlapping in time domain either partially or fully. As discussed in connection with FIGs. 2 & 3, each downlink / uplink opportunity may be associated with a downlink / uplink subframe of a particular TDD frame pattern (e.g., the TDD frame pattern 200 of FIG. 2). For example, the communication opportunity can be one of ULI, UL2, UL3, UL4, DL1, DL2, DL3 or DL4.

[0096] Said any communication opportunity of the serving cell currently usable (or used) by the apparatus may comprise a downlink opportunity or both a downlink opportunity and an uplink opportunity, depending on the status (or state) of the apparatus. Here, said downlink opportunity may correspond to a downlink subframe of a TDD frame pattern (e.g., of FIG. 2) having a particular index (e.g., DL1), and / or said uplink and downlink opportunities may correspond to uplink and downlink subframes of a TDD frame pattern having the same index (e.g., ULI & DL1). Namely, said any communication opportunity of the serving cell currently usable by the apparatus may comprise (or consist of) a downlink (measurement) opportunity of the serving cell when the apparatus is operating in an idle or inactive mode (or state). On the other hand, said any communication opportunity of the serving cell currently usable by the apparatus may comprise (or consist of) both downlink and uplink opportunities of the serving cell when the apparatus is operating in a connected mode (or state). Here and in the following, the idle, inactive and connected modes may be radio resource control (RRC) idle, inactive and connected modes.

[0097] In some embodiments, one exception to the operation discussed in the previous paragraph may exist. Namely, if the apparatus triggers a random access channel (RACH) attempt (i.e., a RACH procedure) while operating in the idle or inactive mode, the apparatus may define said any communication opportunity of the serving cell currently usable by the apparatus to comprise (or consist of) both downlink and uplink opportunities of the serving cell. In other words, said any communication opportunity of the serving cell currently usable by the apparatus may comprise (or consist of), when the apparatus is operating in an idle or inactive mode (or state), a downlink opportunity of the serving cell if no RACH procedure is on-going at the apparatus or downlink and uplink opportunities of the serving cell if a RACH procedure is on-going at the apparatus. If the RACH procedure fails, the apparatus may, again, only take into account the downlink opportunity of the serving cell in block 402.

[0098] In some alternative embodiments, the determination of block 402 may be limited only to downlink opportunity (or downlink opportunities) of the serving cell currently usable (or used) by the apparatus, irrespective of the state or mode of the apparatus. Thus, in these embodiments, said any communication opportunity of the serving cell currently usable (or used) by the apparatus of block 402 may comprise (or consist of) a downlink opportunity of the serving cell currently usable (or used) by the apparatus.

[0099] The determination of block 402 may be based, e.g., on neighbor cell information (comprising, e.g., information identifying one or more neighbor cells of the serving cell and, optionally, one or more satellites providing said one or more neighbor cells and / or information on downlink and uplink opportunities of the one or more neighbor cells) obtained from the serving cell and information on downlink and uplink opportunities of the serving cell, as will be described in further detail in connection with FIG. 5

[0100] Based on the downlink opportunity of the neighbor cell not overlapping with said any communication opportunity of the serving cell currently usable by the apparatus in block 403, the apparatus sets, in block 404, a (timing) scaling factor for a cell reselection process involving one or more satellites to be equal to 1. The scaling factor is usable, at the apparatus, for scaling timing of least one of: cell detection, cell measurements or cell evaluation (for the cell reselection). Said cell evaluation may pertain to evaluation of detected cells. Said scaling factor may be Ksatellitewhich was discussed above at length.

[0101] Based on the downlink opportunity of the neighbor cell overlapping with said any communication opportunity of the serving cell currently usable by the apparatus in block 403, the apparatus sets, in block 405, the scaling factor (e.g., Ksatellite) to be equal to 1.

[0102] Subsequently, the scaling factor may be used, by the apparatus, in at least one cell reselection process carried out by the apparatus. Namely, the apparatus may use the scaling factor for at least one of: scaling the time to detect a new neighbor cell, scaling the time to perform measurements on detected neighbor cell or scaling the time to evaluate the detected and measured neighbor cell for cell reselection.

[0103] In some embodiments, the executing of the cell reselection process by the apparatus comprises at least one of the following steps which use the scaling factor Ksatellite:- performing narrowband reference signal received power (NRSRP) measurements of any intra-frequency neighbor cell at least every Ksatellite *Tmeasure,NB_intra_NC,wherein Ksateiiite is the scaling factor, and Tmeasure,NB_intra_Nc is a pre-defined time reserved for measuring of an intra-frequency cell;- evaluating whether a newly detectable intra-frequency cell meets one or more pre-defined reselection criteria within KSateiiite*Tdetect,NB_intra, wherein Ksateiiite is the scaling factor, and Tdetect,NB_intra_Nc is a pre-defined time reserved for detection of a new intra-frequency cell before evaluating it for cell reselection; or- evaluating whether a detected intra-frequency cell meets one or more predefined reselection criteria within Ksateiiite *Tevaiuate,NB tra-NC, wherein Ksateiiite is the scaling factor, and Tevaiuate.NB intra-Nc is a (pre-defined) time reserved for evaluating a detected intra-frequency cell for cell reselection.

[0104] For example, said one or more pre-defined reselection criteria may comprise at least one of: a criterion requiring that signal quality (or strength) of a serving cell is below a first predefined threshold, a criterion requiring that signal quality (or strength) of a neighbor cell is above a second pre-defined threshold ( suggesting it can offer better service than the current cell), a criterion relating to priority levels assigned to serving and / or neighbor cells or a criterion based on ranking of (neighbor) cells according to their signal quality measurements.

[0105] In some embodiments, only one of the functionalities discussed in connection with blocks 404, 405 may be implemented.

[0106] FIG. 5 illustrates another process for setting value of the scaling factor (e.g., Ksateiiite) for timing of one or more actions relating to a cell reselection process involving one or more satellites according to embodiments. The process of FIG. 5 may be carried out by an apparatus. The apparatus may be a UE, such as a UE 110 of FIG. 1, or a part thereof. In some embodiments, the apparatus may be an NB-IoT UE (e.g., an NB-IoT device of category NB1 or NB2). In the following, the entity carrying out the process of FIG. 5 is called simply an apparatus.

[0107] The process of FIG. 5 is a variation of the process of FIG. 4. Thus, any of the features and definitions discussed in connection with FIG. 4 may apply, mutatis mutandis, in connection with the process of FIG. 5.

[0108] Referring to FIG. 5, the apparatus receives, in block 501, from a first satellite via a (current) serving cell of the apparatus (which is provided by the first satellite), neighbor cell information for one or more neighbor cells of the serving cell. The one or more neighbor cellsare provided by one or more satellites. Said one or more satellites may comprise, in general, the first satellite (i.e., the serving satellite) and / or one or more other (neighbor) satellites. The neighbor cell information may identify the one or more neighbor cells and, for each of the one or more neighbor cells, a satellite providing said neighbor cell (or at least whether or not the satellite providing said neighbor cell is the serving satellite). In some embodiments, said one or more satellites associated with the neighbor cell information may comprise at least a second satellite, that is, the neighbor cell information may pertain to at least one neighbor cell not provided by the first satellite. The neighbor cell information may be broadcasted by the first satellite. The transmission or broadcasting of the neighbor cell information may be initiated by the first satellite acting itself as a base station or by a terrestrial base station using the first satellite as a repeater or frequency converter.

[0109] The neighbor cell information defines (i.e., provides information on) at least one or more downlink opportunities of the one or more neighbor cells. Thus, the neighbor cell information defines at least a downlink opportunity of a neighbor cell provided by the second satellite. Optionally, the neighbor cell information may also define (i.e., provides information on) one or more uplink opportunities of the one or more neighbor cells.

[0110] In addition to comprising information on the downlink (and optionally uplink) opportunities of the one or more neighbor cells, in some embodiments, the neighbor cell information may comprise also, for each or at least one of the one or more neighbor cells, at least one of a frequency band, a carrier frequency, a physical cell identifier (ID) or satellite assistance information (e.g., an ephemeris).

[0111] In some embodiments, said one or more neighbor cells associated with the neighbor cell information may be intra-frequency (neighbor) cells or NB-IoT intra-frequency (neighbor) cells.

[0112] In some embodiments, the neighbor cell information may be received as a part of a system information block (SIB) such as SIB3, SIB4 or SIB5, SIB3-NB, SIB4-NB or SIB5-NB, where SIB3-NB, SIB4-NB and SIB5-NB SIBs defined for NB-IoT devices.

[0113] The apparatus determines, in block 502, based at least on the neighbor cell information, whether the serving cell has a neighbor cell provided by a second satellite.

[0114] The following actions pertaining to blocks 503 to 507 may be carried out as described above in connection with blocks 401 to 405 of FIG. 4 and are, thus, not discussedhere for brevity. However, it should be highlighted here that the determination of whether the downlink opportunity of the neighbor cell overlaps with any communication opportunity of the serving cell currently usable by the apparatus in block 504 may be based on the neighbor cell information as well as on information on downlink and uplink opportunities of the serving cell. Said information on downlink and uplink opportunities of the serving cell may have been obtained from the first satellite previously.

[0115] FIG. 6 illustrates a process for setting value of a scaling factor (e.g., Ksateiiite) for timing of one or more actions relating to cell reselection according to embodiments. The process of FIG. 6 may be carried out by an apparatus. The apparatus may be a UE, such as a UE 110 of FIG. 1, or a part thereof. In some embodiments, the apparatus may be an NB-IoT UE (e.g., an NB-IoT device of category NB1 or NB2). In the following, the entity carrying out the process of FIG. 6 is called simply an apparatus.

[0116] The process of FIG. 6 is a variation of the process of FIG. 4. Thus, any of the features and definitions discussed in connection with FIG. 4 may apply, mutatis mutandis, in connection with the process of FIG. 6. In some embodiments, the additional steps 501, 502 discussed in connection with FIG. 5 may also be implemented in combination with the process of FIG. 6 (even though these features are not explicitly shown in FIG. 6).

[0117] The initial steps of the process of FIG. 6 pertaining to blocks 601 to 603 may fully correspond to actions of blocks 401 to 403 of FIG. 4 and are, thus, not discussed here for brevity.

[0118] The difference between the processes of FIG. 4 and 6 lies in the additional evaluation in block 604, 605. Namely, after it has been determined that the downlink opportunity of a first neighbor cell (called the neighbor cell in previous embodiments), provided by a second satellite, does not overlap with any communication opportunity of the serving cell currently usable by the apparatus in block 603, the apparatus determines, in block 604, whether a downlink opportunity of a second neighbor cell, provided by a third satellite, overlaps with the downlink opportunity of the first neighbor cell. The determination of block 604 may be based, e.g., on neighbor cell information discussed in connection with FIG. 5.

[0119] The third satellite may be, in many ways, similar to the first and second satellites. The third satellite may be, e.g., a LEO orNGSO satellite. The third satellite may employ TDD for communication with the apparatus. The third satellite may employ, for example, the TDD frame pattern 200 of FIG. 2. In some embodiments, the second neighbor cell provided by thethird satellite may be an intra-frequency (neighbor) cell (i.e., a cell operating at the same carrier frequency as the serving cell) or an NB-IoT intra-frequency (neighbor) cell.

[0120] Based on the downlink opportunity of the second neighbor cell not overlapping with the downlink opportunity of the first neighbor cell in block 605, the apparatus sets, in block 606, a (timing) scaling factor (e.g., Ksatellite) for a cell reselection process involving one or more satellites to be equal to 1. Similar to previous embodiments, the scaling factor is usable, at the apparatus, for scaling timing of least one of: cell detection, cell measurements or cell evaluation (for the cell reselection). Said cell evaluation may pertain to evaluation of detected cells. The apparatus may set the scaling factor to be equal to 1 also in the case where no second neighbor cell provided by a third satellite exists in block 605.

[0121] Based on the downlink opportunity of the second neighbor cell overlapping with the downlink opportunity of the first neighbor cell in block 605, the apparatus sets, in block 606, the scaling factor (e.g., Ksatellite) to be equal to 2. Similar to earlier embodiments, the apparatus may set the scaling factor have the value of 2 also in cases where the serving cell has no neighbor cell provided any satellite other than the first satellite and where the downlink opportunity of the first neighbor cell overlaps with any communication opportunity of the serving cell currently usable by apparatus.

[0122] In some embodiments, only one of the functionalities discussed in connection with blocks 606, 607 may be implemented.

[0123] FIG. 7 illustrates another process for setting value of the scaling factor (e.g., Ksatellite) for timing of one or more actions relating to cell reselection according to embodiments. The process of FIG. 7 may be carried out by an apparatus. The apparatus may be a UE, such as a UE 110 of FIG. 1, or a part thereof. In some embodiments, the apparatus may be an NB-IoT UE (e.g., an NB-IoT device of category NB1 or NB2). In the following, the entity carrying out the process of FIG. 7 is called simply an apparatus.

[0124] The process of FIG. 7 is a variation of the process of FIG. 4. Thus, any of the features and definitions discussed in connection with FIG. 4 may apply, mutatis mutandis, in connection with the process of FIG. 7.

[0125] The initial steps of the process of FIG. 7 pertaining to blocks 701 to 703 may fully correspond to actions of blocks 401 to 403 of FIG. 4 and are, thus, not discussed here for brevity.

[0126] The difference between the processes of FIG. 4 and 7 lies in the additional steps of blocks 704 to 708. Namely, after it has been determined that the downlink opportunity of a first neighbor cell (called the neighbor cell in some previous embodiments), provided by a second satellite, does not overlap with any communication opportunity of the serving cell currently usable by the apparatus in block 703, the apparatus determines, in block 704, whether the serving cell has a second neighbor cell which is provided by a third satellite and which has no downlink opportunity overlapping with said any communication opportunity of the serving cell. The determination of block 704 may be based, e.g., on neighbor cell information discussed in connection with FIG. 5.

[0127] Based on the serving cell having the second neighbor cell provided by the third satellite and having no downlink opportunity overlapping with said any communication opportunity of the serving cell in block 705, the apparatus enables, in block 708, radio measurements of the second neighbor cell, in addition to the serving cell and the first neighbor cell, and sets, in block 707, the scaling factor to be equal to 2. Here, it may be assumed that the apparatus is, by default, configured to carry out, at a time, radio measurements of the serving cell and one neighbor cell, at most. Thus, the capabilities of the apparatus are expanded, in block 708, over this default configuration.

[0128] Based on the serving cell not having said second neighbor cell which is provided by the third satellite and has no downlink opportunity overlapping with said any communication opportunity of the serving cell in block 705, the apparatus sets, in block 706, the scaling factor to be equal to 1. This case may be applicable both when the apparatus has no other neighbor cell than the first neighbor cell as well as when the apparatus has at least one further neighbor cell in addition to the first neighbor cell but each of said at least one further neighbor cell has a downlink opportunity overlapping with said any communication opportunity of the serving cell.

[0129] In some alternative embodiments, block 708 may be connected to (i.e., followed by) block 706 (instead of block 707).

[0130] In some embodiments, the functionalities described in connection with FIG. 7 may be combined with any of the embodiments discussed in connection with FIG. 5 or 6.

[0131] In embodiments where processes of FIGs. 6 & 7 are combined, the apparatus may select the value of the scaling factor, for example, in the following manner. Namely, based onthe downlink opportunity of the first neighbor cell, provided by the second satellite, overlapping with no communication opportunity of the serving cell currently usable by the apparatus (i.e., the case of block 603 / 703 (no)), the apparatus may select the scaling factor as follows:• Based on the downlink opportunity of the second neighbor cell overlapping with the downlink opportunity of the first neighbor cell while failing to overlap with said any communication opportunity of the serving cell currently usable by the apparatus, the apparatus may enable radio measurements of the second neighbor cell, in addition to the serving cell and the first neighbor cell, and set the scaling factor to be equal to 2.• Based on the downlink opportunity of the second neighbor cell overlapping with the downlink opportunity of the first neighbor cell and also with said any communication opportunity of the serving cell currently usable by the apparatus, the apparatus may set the scaling factor Ksateiiite to be equal to 2 (without enabling radio measurements of the second neighbor cell).• Based on the downlink opportunity of the second neighbor cell not overlapping with the downlink opportunity of the first neighbor cell and overlapping or not overlapping with said any communication opportunity of the serving cell currently usable by the apparatus, the apparatus may set the scaling factor Ksateiiite to be equal to 1.In some embodiments, one or more of the features indicated above with bullet points (e.g., features of the first two bullet points) may be implemented.

[0132] The blocks, related functions, and information exchanges described above by means of FIGs. 3 to 7 are in no absolute chronological order, and some of them may be performed simultaneously or in an order differing from the given one. Other functions can also be executed between them or within them, and other information may be sent, and / or other rules applied. Some of the blocks or part of the blocks or one or more pieces of information can also be left out or replaced by a corresponding block or part of the block or one or more pieces of information

[0133] FIG. 8 provides an apparatus 801 according to some embodiments. Specifically, FIG. 8 may illustrate an apparatus configured to carry out at least some of the functions described above. The apparatus 801 may be or form a part of a UE. Said UE may be, e.g., an NB-IoT UE (e.g., of category NB1 or NB2).

[0134] The apparatus 801 may comprise one or more communication control circuitry 820, such as at least one processor, and at least one memory 830, including one or morealgorithms 831, such as a computer program code (software) wherein the at least one memory and the computer program code (software) are configured, with the at least one processor, to cause the apparatus 801 to carry out any one of the exemplified functionalities of the apparatus described above in connection with any of FIGs. 3 to 7. Said at least one memory 830 may also comprise at least one database 832.

[0135] When the one or more communication control circuitry 820 comprises more than one processor, the apparatus 801 may be a distributed device wherein processing of tasks takes place in more than one physical unit. Each of the at least one processor may comprise one or more processor cores. A processing core may comprise, for example, a Cortex-A12 processing core manufactured by ARM Holdings or a Zen processing core designed by Advanced Micro Devices Corporation. The one or more control circuitry 820 may comprise at least one Qualcomm Snapdragon and / or Intel Atom processor.

[0136] Referring to FIG. 8, the one or more communication control circuitry 820 of the apparatus 801 is configured to carry out functionalities described above by means of any of elements of FIGs. 3 to 7 using one or more individual circuitries. It may also be feasible to use specific integrated circuits, such as digital signal processing (DSP) block, digital signal processor, an application-specific integrated circuit (ASIC) or a field-programmable gate array (FPGA), or other components and devices for implementing said functionalities in accordance with different embodiments.

[0137] Referring to FIG. 8, the apparatus 801 may further comprise different interfaces 810 such as one or more communication interfaces comprising hardware and / or software for realizing communication connectivity according to one or more communication protocols. For example, the one or more communication interfaces 810 may comprise at least one interface enabling communication between the apparatus and one or more base stations. At least some of said one or more base stations may be satellited-based base stations.

[0138] Referring to FIG. 8, the memory 830 may be implemented using any suitable data storage technology, such as semiconductor based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory.

[0139] As used in this application, the term ‘circuitry’ may refer to one or more or all of the following: (a) hardware-only circuit implementations, such as implementations in onlyanalog and / or digital circuitry, and (b) combinations of hardware circuits and software (and / or firmware), such as (as applicable): (i) a combination of analog and / or digital hardware circuit(s) with software / firmware and (ii) any portions of hardware processor(s) with software, including digital signal processor(s), software, and memory(ies) that work together to cause an apparatus, such as a terminal device or an access node, to perform various functions, and (c) hardware circuit(s) and processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g. firmware) for operation, but the software may not be present when it is not needed for operation. This definition of ‘circuitry’ applies to all uses of this term in this application, including any claims. As a further example, as used in this application, the term ‘circuitry’ also covers an implementation of merely a hardware circuit or processor (or multiple processors) or a portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware.

[0140] In an embodiment, at least some of the processes described in connection with FIGs. 3 to 7 may be carried out by an apparatus comprising corresponding means for carrying out at least some of the described processes. Some example means for carrying out the processes may include at least one of the following: detector, processor (including dual -core and multiplecore processors), digital signal processor, controller, receiver, transmitter, encoder, decoder, memory, register, multiply-accumulate (MAC) unit, delay element, RAM, ROM, software, firmware, display, user interface, display circuitry, user interface circuitry, user interface software, display software, circuit, filter (low-pass, high-pass, bandpass and / or bandstop), sensor, circuitry, inverter, capacitor, inductor, resistor, operational amplifier, diode and transistor. In some embodiments, at least some of the processes may be implemented using discrete components. In an embodiment, at least some of the processes described in connection with FIGs. 3 to 7 may be carried out by an apparatus comprising corresponding hardware means for carrying out at least some of the described processes. Said hardware means may comprise at least one of: a multiplier, an adder, a MAC unit, a barrel shifter, a register, a shift register, a memory unit, a control logic, a clocking circuitry or a finite state machine.

[0141] According to an embodiment, there is provided an apparatus (e.g., a UE) comprising means for performing:based on a serving cell, provided by a first satellite, having a neighbor cell provided by a second satellite,- determining whether a downlink opportunity of the neighbor cell overlaps with any communication opportunity of the serving cell currently usable by the apparatus, and- based on the downlink opportunity of the neighbor cell not overlapping with any communication opportunity of the serving cell currently usable by the apparatus, setting a scaling factor for a cell reselection process involving one or more satellites to be equal to 1, wherein the scaling factor is usable, at the apparatus, for scaling timing of least one of: cell detection, cell measurements or cell evaluation for cell reselection.

[0142] According to an embodiment, there is provided an apparatus (e.g., a UE) comprising means for performing:based on a serving cell of the apparatus, being provided by a first satellite, having a first neighbor cell provided by a second satellite,- determining whether a downlink opportunity of the first neighbor cell overlaps with any communication opportunity of the serving cell currently usable by the apparatus, and- based on the downlink opportunity of the first neighbor cell not overlapping with said any communication opportunity of the serving cell currently usable by the apparatus,• determining whether a downlink opportunity of a second neighbor cell, provided by a third satellite, overlaps with the downlink opportunity of the first neighbor cell; and • based on the downlink opportunity of the second neighbor cell not overlapping with the downlink opportunity of the first neighbor cell, setting a scaling factor for a cell reselection process involving one or more satellites to be equal to 1, wherein the scaling factor is usable, at the apparatus, for scaling timing of least one of: cell detection, cell measurements or cell evaluation for cell reselection.

[0143] Embodiments as described above may also be carried out, fully or at least in part, in the form of a computer process defined by a computer program or portions thereof. Embodiments of the methods described in connection with FIGs. 3 to 6 may be carried out by executing at least one portion of a computer program comprising corresponding instructions. The computer program may be provided as a computer readable medium comprising program instructions stored thereon or as a non-transitory computer readable medium comprising program instructions stored thereon. The computer program may be in source code form, object code form, or in some intermediate form, and it may be stored in some sort of carrier, which may be any entity or device capable of carrying the program. For example, the computer program may be stored on a computer program distribution medium readable by a computer or a processor. The computer program medium may be, for example but not limited to, a record medium, computer memory, read-only memory, electrical carrier signal, tele-communications signal, and software distribution package, for example. The computer program medium may bea non-transitory medium. Coding of software for carrying out the embodiments as shown and described is well within the scope of a person of ordinary skill in the art.

[0144] The term “non-transitory”, as used herein, is a limitation of the medium itself (that is, tangible, not a signal) as opposed to a limitation on data storage persistency (for example, RAM vs. ROM).

[0145] Reference throughout this specification to one embodiment or an embodiment means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present solution. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment.

[0146] As used herein, a plurality of items, structural elements, compositional elements, and / or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary. In addition, various embodiments and example of the present solution may be referred to herein along with alternatives for the various components thereof. It is understood that such embodiments, examples, and alternatives are not to be construed as de facto equivalents of one another, but are to be considered as separate and autonomous representations of the present solution.

[0147] Even though embodiments have been described above with reference to examples according to the accompanying drawings, it is clear that the embodiments are not restricted thereto but can be modified in several ways within the scope of the appended claims. Therefore, all words and expressions should be interpreted broadly and they are intended to illustrate, not to restrict, the embodiment. It will be obvious to a person skilled in the art that, as technology advances, the inventive concept can be implemented in various ways. Further, it is clear to a person skilled in the art that the described embodiments may, but are not required to, be combined with other embodiments in various ways.INDUSTRIAL APPLICABILITY

[0148] At least some embodiments find industrial application in non-terrestrial cellular communications.

Claims

34CLAIMS1. A user equipment comprising:at least one processor; andat least one memory storing instructions that, when executed by the at least one processor, cause the user equipment at least to perform:based on a serving cell of the user equipment, being provided by a first satellite, having a first neighbor cell provided by a second satellite,- determining whether a downlink opportunity of the first neighbor cell overlaps with a downlink opportunity of the serving cell currently usable by the user equipment when the user equipment is operating in an idle mode, and- based on the downlink opportunity of the first neighbor cell not overlapping with the downlink opportunity of the serving cell currently usable by the user equipment, , setting a scaling factor for a cell reselection process involving one or more satellites to be equal to 1, wherein the scaling factor is usable, at the user equipment, for scaling timing of least one of: cell detection, cell measurements or cell evaluation for cell reselection.

2. The user equipment of claim 1, wherein the at least one memory and the instructions are configured, with the at least one processor, to cause the user equipment to perform, based on the serving cell having the first neighbor cell provided by the second satellite,- based on the downlink opportunity of the first neighbor cell overlapping with the downlink opportunity of the serving cell currently usable by the user equipment, setting the scaling factor to be equal to 2.

3. The user equipment according to any preceding claim, wherein the at least one memory and the instructions are configured, with the at least one processor, to cause the user equipment to perform:based on the serving cell having no neighbor cell provided by the second satellite, setting the scaling factor to be equal to 1.

4. The user equipment according to any preceding claim, wherein the first neighbor cells is an intra-frequency neighbor cell.

355. The user equipment according to any preceding claim, wherein the at least one memory and the instructions are configured, with the at least one processor, to cause the user equipment to execute the cell reselection process using the scaling factor.

6. The user equipment of claim 5, wherein the executing of the cell reselection process comprises:performing narrowband reference signal received power, NRSRP, measurements of any intra-frequency neighbor cell at least every Ksateiiite *Tmeasure,NB_intra_NC, wherein Ksateiiite is the scaling factor, and Tmeasure,NBjntra_NC is a pre-defined time reserved for measuring of an intra-frequency cell.

7. The user equipment of claim 5 or 6, wherein the executing of the cell reselection process comprises:evaluating whether a detectable intra-frequency cell meets one or more pre-defined reselection criteria within KSateiiite*Tdetect,NB_intra, wherein Ksateiiite is the scaling factor, and Tdetect,NB intra NC is a pre-defined time reserved for detection of a new intra-frequency cell before evaluating it for cell reselection.

8. The user equipment according to any of claims 5 to 7, wherein the executing of the cell reselection process comprises:evaluating whether a detected intra-frequency cell meets one or more pre-defined reselection criterion within Ksateiiite *Tevaiuate,NB_intra-NC, wherein Ksateiiite is the scaling factor, and Tevaiuate.NB intra-Nc is a pre-defined time reserved for evaluating a detected intra-frequency cell for cell reselection.

9. The user equipment according to any preceding claim, wherein the serving cell and the first neighbor cell employ time division duplexing, TDD, for communication with the user equipment.

10. The user equipment of claim 9, wherein the serving cell and the first neighbor cell employ a TDD frame structure comprising a n downlink subframes and n uplink subframes, the n downlink subframes and n uplink subframes being paired one-to-one to form n uplinkdownlink subframe pairs, and one uplink-downlink subframe pair, defining uplink and downlink opportunities, being active at any given time, n being a positive integer.

11. The user equipment according to any preceding claim, wherein the first satellite is a first low-Earth orbit, LEO, satellite or a first non-geostationary orbit, NGSO, satellite, and the second satellite is a second LEO satellite or a second NGSO satellite.

12. The user equipment according to any preceding claim, wherein the user equipment is a Narrowband Internet of Things user equipment, NB-IoT UE.

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