Soft satellite cell switch

Abstract

A method and apparatus are disclosed. A method (500) in a wireless device for switching between a first satellite serving a cell and a second satellite serving the cell during a period of overlap is described. The cell is comprised in a terrestrial footprint served by one or more satellite-based radio access nodes, and the wireless device capable of receiving synchronization signal blocks, SSB's, and system information blocks, SIBs, from both satellites serving the cell during the period of overlap. The method includes receiving (510) a first satellite specific SIB, from the first satellite serving the cell, the SIB comprising subframe timing information, comprising a timing offset for the SSB of the second satellite serving the cell, wherein the timing offset has a half-frame granularity. The method also includes the wireless device, upon determining that a switch to the second satellite serving the cell is to be performed, determining (520) a timing of a SSB for the second satellite serving the cell. Also, the method includes synchronizing (530) with the second satellite serving the cell based on detecting the SSB corresponding to the second satellite serving the cell.

Description

[0001] SOFT SATELLITE CELL SWITCH

[0002] TECHNICAL FIELD

[0003] The present disclosure concerns satellite based cellular communications, and in particular, the soft switching between satellites providing a terrestrial cell for the cellular communication serving a land based wireless device.

[0004] BACKGROUND

[0005] There is an ongoing resurgence of satellite communications. Several plans for satellite networks have been announced in the past few years. The target services vary, from backhaul and fixed wireless, to transportation, to outdoor mobile, to loT. Satellite networks could complement mobile networks on the ground by providing connectivity to underserved areas and multicast / broadcast services. Certain aspects of the disclosure and their embodiments may provide solutions to these or other challenges.

[0006] To benefit from the strong mobile ecosystem and economy of scale, adapting the terrestrial wireless access technologies including long term evolution (LTE) and new radio (NR) for satellite networks is drawing significant interest, which has been reflected in the 3rdGeneration Partnership Project (3GPP) standardization work. In 3GPP release 15, 3GPP started the work to prepare NR for operation in a Non-Terrestrial Network (NTN).

[0007] In this document, unless explicitly stated otherwise, the term Non-Terrestrial Network -NTN - refers to aNRNTN, i.e. aNTN that operates according to 3GPP NR technology adapted to satellite communication.

[0008] The work was performed within the study item “NR to support Non-Terrestrial Networks” and resulted in 3GPP TR 38.811 V15.4.0 (2020-09) Study on New Radio (NR) to support non-terrestrial networks (Release 15). In 3GPP release 16, the work to prepare NR for operation in an NTN network continued with the study item “Solutions for NR to support NonTerrestrial Network”, which has been captured in 3GPP TR 38.821 V16.2.0 (2023-03) Solutions for NR to support non-terrestrial networks (NTN) (Release 16). In parallel the interest to adapt narrowband internet of things (NB-IoT) and LTE for machine type communications (LTE-M) for operation in NTN is growing. As a consequence, 3 GPP release 17 contains both a work item on NR NTN, on which NTN related specification in 3GPP release 17 has been based, and a study item and work item on NB-IoT and LTE-M support for NTN.In 3GPP Release 18, the feature “satellite switch with resync” was introduced and specified. This is relevant for the present invention and is elaborated further below.

[0009] A satellite radio access network usually includes the following components:

[0010] - A satellite that refers to a space-home platform. An earth-based gateway that connects the satellite to a base station or a core network, depending on the choice of architecture.

[0011] - A feeder link that refers to the link between a gateway and a satellite. - An access link, or service link, that refers to the link between a satellite and aUE.

[0012] Depending on the orbit altitude, a satellite may be categorized as low earth orbit (LEO), medium Earth orbit (MEO), or geostationary Earth orbit (GEO) satellite.

[0013] - LEO: typical heights ranging from 250 - 1,500 km, with orbital periods ranging from 90 - 120 minutes.

[0014] MEO: typical heights ranging from 1,500 - 35,786 km, with orbital periods, PMEO, in the range 2 hours < PMEO < 24 hours. MEO and LEO are also known as Non-Geo Synchronous Orbit (NGSO) type of satellite.

[0015] GEO: height at about 35,786 km, with an orbital period of 24 hours. Also known as a Geo Synchronous Orbit (GSO) type of satellite.

[0016] Two basic architectures can be distinguished for satellite communication networks, depending on the functionality of the satellites in the system:

[0017] - Transparent payload (also referred to as bent pipe architecture). The satellite forwards the received signal between the terminal and the network equipment on the ground with only amplification and a shift from uplink frequency to downlink frequency. When applied to general 3GPP architecture and terminology, the transparent payload architecture means that the NR Node B (gNB) is located on the ground and the satellite forwards signals / data between the gNB and the UE Regenerative pay load. The satellite includes on-board processing to demodulate and decode the received signal and regenerate the signal before sending it back to the Earth. When applied to general 3 GPP architecture and terminology, the regenerative payload architecture means that the gNB is located in the satellite.In the work item for NR NTN in 3GPP release 17 and release 18, only the transparent payload architecture is considered.

[0018] Figure 1 shows an example architecture of a satellite network with bent pipe transponders (i.e., the transparent payload architecture). The gNB (depicted as base station ‘BS’ in Figure 1) may be integrated in the gateway or connected to the gateway via a terrestrial connection (wire, optic fiber, wireless link).

[0019] The significant orbit height means that satellite systems are characterized by a path loss that is significantly higher than what is expected in terrestrial networks. To overcome the pathloss it is often required that the access and feeder links are operated in line-of-sight conditions, and that the UE is equipped with an antenna offering high beam directivity.

[0020] A communication satellite typically generates several beams over a given area. The footprint of a beam is usually in an elliptic shape, which has been traditionally considered as a cell (but a cell consisting of multiple beams is not precluded). In some examples the footprint is comprised of multiple cells and / or multiple beams. The footprint of a beam is also often referred to as a spotbeam (as depicted in Figure 1). The spotbeam may move over the Earth surface with the satellite movement (and the Earth’s rotation) or may be Earth fixed with some beam pointing mechanism used by the satellite to compensate for its motion. The size of a spotbeam depends on the system design and may range from tens of kilometers to a few thousands of kilometers.

[0021] The NTN beam may in comparison to the beams observed in a terrestrial network provide a very wide footprint and may cover an area outside of the area defined by the served cell. Beam covering adjacent cells will overlap and cause significant levels of intercell interference, resulting from the slow decrease of the signal strength in the outwards radial direction. This is due in part to the high elevation angle and long distance to the network-side (satellite-home) transceiver, which, compared with terrestrial cells, results in a comparatively small relative difference between the distance from the cell center to the satellite and the distance from a point at the cell edge to the satellite. To overcome the large levels of interference, a typical approach in NTN is to configure different cells with different carrier frequencies and polarization modes.

[0022] Three types of beams or cells are supported in NTN:

[0023] • Earth-fixed beams / cells: provisioned by beam(s) continuously covering the same geographical areas all the time (e.g., in the case of GEO satellites).• Quasi-Earth-fixed beams / cells: provisioned by beam(s) covering one geographic area for a limited period and a different geographic area during another period (e.g., in the case of non GEO stationary orbit (NGSO) satellites generating steerable beams).

[0024] • Earth-moving beams / cells: provisioned by beam(s) whose coverage area slides over the earth surface (e.g., in the case of NGSO satellites generating fixed or non-steerable beams).

[0025] Throughout this disclosure the use of the terms beam and cell are interchangeable, unless explicitly noted otherwise.

[0026] Of the three above cell types, quasi-Earth-fixed cells and moving cells seem to be the ones most promising for actual deployment. In the case of moving cells, each cell (the footprint of its beam(s)) moves across the surface of the Earth as its serving satellite moves along its orbit.

[0027] The same satellite will only be able to cover the same area on the Earth for a limited time, unless the satellite is in a geostationary orbit (and note that LEO satellites have the most traction in the satellite communication industry). In the case of moving cells, each cell moves along the surface of the Earth as the satellite serving it moves along its orbit above. Hence, as seen from the ground, cells gradually replace each other over any given area. In the case of quasi-Earth-fixed cells, the cell area (as the name implies) remains fixed to the same geographical area, regardless of satellite movements. To enable this, a serving satellite has to have means for dynamically directing its beam(s), so that the same area of the Earth is covered despite the satellite’s movement. However, since the satellites orbit around the Earth, it is inevitable that different satellites will have the task of covering a certain geographical cell area at different time periods. When this task is switched from one satellite to another, this in principle means that one cell is replaced by another, although covering the same area (often referred to as a cell switch).

[0028] As a consequence, all UEs connected in the old cell (i.e., UEs in RRC_CONNECTED state) have to be handed over (or otherwise moved, e.g. using Radio Resource Control (RRC) connection reestablishment) from the old to the new cell, and all UEs camping on the old cell (i.e., UEs in RRC IDLE or RRC INACTIVE state) have to perform cell reselection to the new cell. When the satellite serving the area is changed, so that an old cell disappears and a new cell appears, this is referred to as a satellite switch. A consequence of a satellite switch is thatboth the service link (i.e. the link between the UE and the satellite) and the feeder link (i.e. the link between the satellite and the gateway (GW) / gNB) are switched.

[0029] A similar situation occurs in conjunction with feeder link switches, i.e. when the serving satellite remains the same, but its connection to the ground changes from one (old) GW / gNB to another (new) GW / gNB. Also in this case there is a switch between an old cell and a new cell (i.e. the old cell is replaced by a new cell).

[0030] Satellite switches and feeder link switches can both be referred to with the umbrella term “cell switch”.

[0031] In terms of such cell switches there are two alternative principles: 1) hard switch; and 2) soft switch. With hard switch, there is an instantaneous switch from the old to the new cell, i.e., the new cell appears at the same time as the old cell disappears (or with a small time gap in between). This makes completely seamless (i.e., interruption free) handover in practice impossible and creates a situation which may lead to overload of the access resources in the new cell, due to potential access attempt peaks when many UEs try to access the new cell right after the cell switch.

[0032] With soft switch there is a time period during which the new and the old cell coexist (i.e. overlap), covering the same geographical area. This coexistence / overlap period allows some time for connected UEs to perform measurements and to be handed over to the new cell, and for UEs in RRC IDLE state and RRC INACTIVE state (i.e. UEs camping in the cell) to reselect to the new cell. Thus, the coexistence / overlap period of the two cells facilitates distribution of the access load in the new cell and thereby also provides better conditions for handovers with shorter interruption time. Soft switch is likely to be the most prevalent cell switch principle in quasi-Earth-fixed cell deployments.

[0033] Yet another possible deployment option is what is usually referred to as discontinuous coverage. With discontinuous coverage, NGSO satellites orbit the Earth, providing coverage to moving or quasi-Earth-fixed cells. What characterizes a discontinuous coverage deployment is that when a satellite ceases to provide coverage in a certain location, another satellite does not immediately take over this task. Instead, the location is left without coverage for a certain time until another satellite (or possibly even the same satellite) starts to provide coverage in the location. Discontinuous coverage can thus be seen as a consequence of sparse satellite deployment. It may typically be used during an early phase where the satellite constellation is still being built up and the number of deployed satellites gradually increase. Alternatively, it can be a deployment alternative chosen to reduce the cost of the NTN, e.g. in cases where thetargeted customers and applications are insensitive to access delays. In terms of standard specification, special support for discontinuous coverage has so far mainly been taken into account in the specification of the LTE based loT NTN.

[0034] The gNB and the GW may be separate entities which are spatially separate with a non-negligible propagation delay between them, or they can be integrated in a single entity, or separate entities but collocated in a way that the propagation delay between them is negligible. The inventive mechanisms presented herein are applicable in all cases if the (somewhat inappropriate) definition of the feeder link is the communication link between the satellite and the gNB.

[0035] Ephemeris data (sometimes referred to as “ephemeris information” or “ephemeris parameters” or just “ephemeris”) is data that allows a UE (or other entity) to determine a satellite’s position and velocity, i.e., the ephemeris data contains parameters related to the satellite’s orbit. There are several different formats defined for ephemeris data.

[0036] In TR 38.821 it has been captured that ephemeris data should be provided to the UE, for example to assist with pointing a directional antenna (or an antenna beam) towards the satellite, and to calculate a correct Timing Advance (TA) and Doppler shift. In NR NTN and loT NTN, ephemeris data is broadcast in the system information (SI) in each cell, included in an NTN specific system information block (SIB), (labeled SIB 19 in NR NTN and SIB31 loT NTN, see section 2.2.2.4).

[0037] A satellite orbit can be fully described using 6 parameters. Exactly which set of parameters is chosen can be decided by the user; many different representations are possible. For example, a choice of parameters used often in astronomy is the set (a, e, i, Q. co, t). Here, the semi-major axis a and the eccentricity e describe the shape and size of the orbit ellipse; the inclination i, the right ascension of the ascending node Q. and the argument of periapsis co determine its position in space, and the epoch time t determines a reference time (e.g. the time when the satellites moves through periapsis). This set of parameters is illustrated in Figure 2.

[0038] As an example of a different parametrization, the Two-Line Element sets (TLE)s use mean motion n and mean anomaly M instead of a and t. A completely different set of parameters is the position and velocity vector (x, y, z, vx, vy, vz) of a satellite. These are sometimes called orbital state vectors. They can be derived from the orbital elements and vice versa, since the information they contain is equivalent. All these formats (and many others) are possible choices for the format of ephemeris data to be used in NTN.An aspect discussed during the 3GPP study item and captured in 3GPP TR 38.821 is the validity time of ephemeris data. Predictions of satellite positions in general degrade with increasing age of the ephemeris data used, due to atmospheric drag, maneuvering of the satellite, imperfections in the orbital models used, etc. Therefore, the publicly available TLE data are updated quite frequently. For example, the update frequency depends on the satellite and its orbit and ranges from weekly to multiple times a day for satellites on very low orbits which are exposed to strong atmospheric drag and need to perform correctional maneuvers often. Even more frequent updates will be used in NR NTN (and loT NTN) to allow the UE to determine / predict the satellite’s position (and velocity) accurately enough to satisfy the requirements in NTN, e.g., to enable a UE to calculate an accurate enough UE-specific TA. In NR NTN, the ephemeris data and the validity time of the ephemeris data is provided to the UE in the ntn-Config IE in the NTN specific SIB, SIB19 (see section 2.2.1.4).

[0039] Propagation delay is an important aspect of satellite communication. Its expected impacts in NTN is different from the impacts of propagation delay in a terrestrial mobile system. For a bent pipe satellite network, the UE-gNB round-trip delay may, depending on the orbit height, range from a few or tens of ms in the case of LEO satellites to several hundreds of ms for GEO satellites. As a comparison, the round-trip delays in terrestrial cellular networks are typically below 1 ms.

[0040] The distance between the UE and a satellite can vary significantly, depending on the position of the satellite and thus the elevation angle seen by the UE. The propagation delay may also be highly variable due to the high velocity of the LEO and MEO satellites and change in the order of 10 - 100 ps every second, depending on the orbit altitude and satellite velocity.

[0041] The long propagation delays in NTN have many consequences, one of which being that large Timing Advance (TA) values have to be used (where a TA is the time a UE has to advance its UL transmission in relation to the corresponding frame, slot and symbol in the DL to achieve alignment between the uplink (UL) and the downlink (DL) frame / slot / symbol structure at an UL / DL alignment reference point, which typically is the gNB). In addition, due to the fast movement of the satellite (excluding GEO satellites), the TA will continuously change and will do so quite rapidly. 3GPP has dealt with these circumstances through a combination of new parameters and introduction of the principle of UE autonomous adaptation of the TA.

[0042] To take care of the part of the TA that is common for all UEs in the cell, the satellite broadcasts in the system information (SIB 19 in NR NTN and SIB31 in loT NTN) so-called Common TA information, consisting of a Common TA value. The UE specific part of the TA,i.e., the UE-satellite RTT is left to the UE to autonomously calculate. To do this, the UE has to obtain its own location and the satellite position. The UE can obtain its own location e.g., using GNSS measurements, and the satellite’s position (as well as its velocity) can be derived from the ephemeris data broadcast by the gNB (in the same SIB as the Common TA parameters). The ephemeris data and the Common TA parameters are nominally valid at a so-called epoch time, which is also indicated in the same SIB (or, if the epoch time indication is absent in the SIB, the epoch time is assumed to be the end of the system information (SI) window in which the SIB was received). Based on the ephemeris data, the UE can predict the satellite’s position a certain time into the future, and the first and second time derivatives (i.e., the drift and drift variation parameters) of the Common TA allows the UE to calculate how the Common TA value changes with time. Furthermore, the broadcast ephemeris data and Common TA parameters have a limited validity time, which is also indicated in the same SIB. The ephemeris data and Common TA parameters the UE uses when calculating the UE specific TA have to be valid, i.e. their validity time must not have expired. The same goes for the UE location information, typically based on a GNSS measurement, the UE uses in the TA calculation (in particular to calculate the UE-satellite round trip time, RTT).

[0043] In a LEO or MEO communication system, a large number of satellites deployed over a range of orbits is required to provide continuous coverage across the full globe. Launching a mega satellite constellation is both an expensive and time-consuming procedure. It is therefore expected that some satellite constellations will only provide partial earth-coverage, or full but locally intermittent earth-coverage. In case of some constellations dedicated to massive loT services with relaxed latency requirements, it may not even be necessary to support full earthcoverage. It may be sufficient to provide occasional or periodic coverage according to the orbital period of the constellation.

[0044] SUMMARY

[0045] To address the problems described herein, multiple partly inter-related solutions are provided. They apply both to temporary and permanent shifting of the synchronization signal blocks (SSB)s during soft satellite switch with resync, although some specific aspects mainly target temporary SSB shifting.

[0046] The tools that are used to address the problems comprise:Restricting the granularity of the time-shifts of the SSBs to steps of half-frames (i.e. steps of 5 subframes) or even whole frames.

[0047] Time-shifting of SSBs.

[0048] Frequency-shifting of SSBs.

[0049] Unchanged SSB content (decoupled from the SSB location while shifted).

[0050] Indication of “special” SSB, e.g. shifted SSB without associated SIB1.

[0051] SSBs without PBCH.

[0052] Some of the solutions may be extended with an indication in the time- and / or frequency-shifted SSB informing UEs of the special nature of the SSB.

[0053] The essence of the invention is to avoid the problems described previously by using timeshifting with restricted granularity or decoupling the SSB content from the time domain structure and / or applying frequency-shifting of the SSBs.

[0054] Certain embodiments may provide one or more of the following technical advantage(s). The solution eliminates or at least mitigates the problems associated with a time-shifted SSB being out of sync with the time domain frame / slot structure.

[0055] In a first aspect a method performed by a wireless device for switching between a first satellite serving a cell and a second satellite serving the cell during a period of overlap is provided. The cell is comprised in a terrestrial footprint served by one or more satellite-based radio access nodes. The wireless device being capable of receiving synchronization signal blocks, SSB’s, and system information blocks, SIBs, from both satellites serving the cell during the period of overlap. The method comprising receiving a first satellite specific SIB, from the first satellite serving the cell, the SIB comprising subframe timing information, comprising a timing offset for the SSB of the second satellite serving the cell, wherein the timing offset has ahalf-frame granularity. The method further comprising the wireless device, upon determining that a switch to the second satellite serving the cell is to be performed, determining a timing of a SSB for the second satellite serving the cell. The wireless device furthermore performing the step of synchronizing with the second satellite serving the cell based on detecting the SSB corresponding to the second satellite serving the cell.

[0056] In some examples of the first aspect, the timing offset comprises a restriction to an ssb-TimeOffset parameter signalled in the satellite specific SIB.

[0057] In some examples of the first aspect, the first satellite serving the cell is a source satellite and the second satellite serving the cell is a target satellite.

[0058] In some examples of the first aspect, the SSB from the second satellite serving the cell istemporarily distinguishable from the SSB of the first satellite serving the cell and receiving a subsequent SSB from the second satellite serving the cell which is no longer distinguishable from the SSB from the first satellite serving the cell.

[0059] In some examples of the first aspect, the physical channel in which the SSB of the second satellite serving the cell is transmitted is scrambled according to a sequence identified in the first satellite specific SIB.

[0060] In some examples of the first aspect, the timing offset is used only to indicate the timing of the SSB and the associated SSB content is configured according to the SSB timing without the offset.

[0061] In some examples of the first aspect, the SSB of the second satellite serving the cell is distinguished from the SSB of the first satellite serving the cell by the first satellite specific SIB information indicating a frequency shift for the SSB of the second satellite serving the cell.

[0062] In some examples of the first aspect, the information indicating the frequency shift for the SSB of the second satellite serving the cell is temporary and only applies when the SSB of the second satellite serving the cell is transmitted when the SSB of the first satellite serving the cell is still being transmitted.

[0063] In some examples of the first aspect, the frequency shift is used only to distinguish the SSB of the second satellite serving the cell from the SSB of the first satellite serving the cell and the associated SSB content is configured according to the SSB frequency / subcarrier offset without the frequency shift.

[0064] In some examples of the first aspect, the frequency-shift is pre-defined (e.g. with different shift sizes depending on the carrier frequency and / or the carrier bandwidth) and the time-shift is indicated in the first satellite specific SIB.

[0065] In a second aspect, a method performed by a network node for switching between a first satellite serving a cell and a second satellite serving the cell is provided. The cell is comprised in a terrestrial footprint served by one or more satellite based radio access nodes. The method comprising causing a transmission of a first satellite specific system information block, SIB, from the first satellite serving the cell, the SIB comprising subframe timing information comprising a timing offset for a synchronization signal block, SSB, of the second satellite serving the cell, wherein the timing offset has a half-frame granularity. The method further comprises the network node causing an indication to at least one served wireless device that a switch to the second satellite serving the cell is to be performed. The method furthermore comprises the step of the network node causing a transmission of an SSB for the second satelliteserving the cell from the second satellite serving the cell, based on the indicated timing offset. In some examples of the second aspect, the timing offset comprises a restriction to an s sb -TimeOffset parameter signalled in the satellite specific SIB.

[0066] In some examples of the second aspect, the first satellite serving the cell is a source satellite and the second satellite serving the cell is a target satellite.

[0067] In some examples of the second aspect, the SSB from the second satellite serving the cell is temporarily distinguishable from the SSB of the first satellite serving the cell and causing the transmission of a subsequent SSB from the second satellite serving the cell which is no longer distinguishable from the SSB from the first satellite serving the cell.

[0068] In some examples of the second aspect, the physical channel in which the SSB of the second satellite serving the cell is transmitted is scrambled according to a sequence identified in the first satellite specific SIB.

[0069] In some examples of the second aspect, the timing offset is used only to indicate the timing of the SSB and the associated SSB content is configured according to the SSB timing without the offset.

[0070] In some examples of the second aspect, the SSB of the second satellite serving the cell is distinguished from the SSB of the first satellite serving the cell by the first satellite specific SIB information indicating a frequency shift for the SSB of the second satellite serving the cell.

[0071] In some examples of the second aspect, the information indicating the frequency shift for the SSB of the second satellite serving the cell is temporary and only applies when the SSB of the second satellite serving the cell is transmitted when the SSB of the first satellite serving the cell is still being transmitted.

[0072] In some examples of the second aspect, the frequency shift is used only to distinguish the SSB of the second satellite serving the cell from the SSB of the first satellite serving the cell and the associated SSB content is configured according to the SSB frequency / subcarrier offset without the frequency shift.

[0073] In some examples of the second aspect, the frequency-shift is pre-defined (e.g. with different shift sizes depending on the carrier frequency and / or the carrier bandwidth) and the time-shift is indicated in the first satellite specific SIB.

[0074] In some examples of the second aspect, the network node is a satellite access network, SAN, comprising terrestrial based base station functions and non-terrestrial satellite based functions, e.g. adaptive antenna systems and payload transfer functions onboard the satellite.

[0075] In some examples of the second aspect, the terrestrial functions of the SAN control thefirst and the second satellite based functions serving the cell.

[0076] In a third aspect, a wireless device for switching between a first satellite serving a cell and a second satellite serving the cell is provided. The cell is comprised in a terrestrial footprint served by one or more satellite-based radio access nodes. In some examples of the third aspect, the wireless device comprises processing circuitry and a power source configured to supply power to the processing circuitry. The wireless device being configured to receive a first satellite specific system information block, SIB, from the first satellite serving the cell, the SIB comprising subframe timing information, comprising a timing offset for the SSB of the second satellite serving the cell, wherein the timing offset has a half-frame granularity. The wireless is further configured to determine that a switch to the second satellite serving the cell is to be performed and determine a timing of a SSB for the second satellite serving the cell. Furthermore, the wireless device is configured to synchronize with the second satellite serving the cell based on detecting the SSB corresponding to the second satellite serving the cell.

[0077] In further examples of the third aspect, the wireless device is configured to perform any of the methods previously described pertaining to a wireless device.

[0078] In a fourth aspect, a network node for switching between a first satellite serving a cell and a second satellite serving the cell is provided. The cell is comprised in a terrestrial footprint served by one or more satellite based radio access nodes. In some examples of the fourth aspect the network node comprises processing circuitry and a power source circuitry configured to supply power to the processing circuitry. The network node being configured to cause the transmission of a first satellite specific system information block, SIB, from the first satellite serving the cell, the SIB comprising subframe timing information comprising a timing offset for a synchronization signal block, SSB, of the second satellite serving the cell, wherein the timing offset has a half-frame granularity. The network node being further configured to cause an indication to at least one served wireless device that a switch to the second satellite serving the cell is to be performed. Furthermore, the network node is configured to cause the transmission of an SSB for the second satellite serving the cell from the second satellite serving the cell, based on the indicated timing offset.

[0079] In further examples of the fourth aspect, the network node is configured to perform any of the methods previously described pertaining to a network node.

[0080] BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1: Depicts a satellite based radio access network according to certain embodiments disclosed herein.

[0081] FIG. 2: Depicts certain ephemeris parameters used in one or more embodiments disclosed herein.

[0082] FIG. 3: Depicts the time shift of SSBs according to one or more embodiments disclosed herein.

[0083] FIG. 4: Depicts the frequency shift of SSBs according to one or more embodiments disclosed herein.

[0084] FIG. 5: Depicts a flow chart according to one or more embodiments disclosed herein. FIG. 6: Depicts a flow chart according to one or more embodiments disclosed herein. FIG. 7 shows an example of a communication system 700 in accordance with some embodiments.

[0085] FIG. 8 is another example of a communication system 800 according to some embodiments.

[0086] FIG. 9 shows a wireless device 900, which may be configured to operate in communication system 700 of Figure 7 or in communication system 800 of Figure 8.

[0087] FIG. 10 shows a network node 1000 in accordance with some embodiments.

[0088] FIG. 11 is a block diagram illustrating a virtualization environment 1100 in which functions implemented by some embodiments may be virtualized.

[0089] DETAILED DESCRIPTION

[0090] Some of the embodiments contemplated herein will now be described more fully with reference to the accompanying drawings. Embodiments are provided by way of example to convey the scope of the subject matter to those skilled in the art.

[0091] The solutions and embodiments outlined below are described in terms of NR-based NTNs, but they may also be applicable to future NTN standards, e.g. 6G, as well as to further development of the LTE-based loT NTN.

[0092] The term “network” is used in the solution description to refer to a network node, which typically will be a gNB, but which may also be another type of node serving a similar purpose in another system or RAT, e.g. in a 6GNTN.

[0093] The terms “idle mode”, “RRC IDLE state” or “RRC IDLE mode” are used interchangeably in this document. Similarly, the terms “inactive mode”, “RRC INACTIVE state” or “RRC INACTIVE mode” are used interchangeably in this document.Herein the value of t-service-rl7 is sometimes referred as “remaining service time” or “current cell stop serving time”. This parameter typically informs the UE when the satellite (normally operating in a LEO or MEO) that is serving the cell to which the UE is connected will stop serving the area due to its movement or when the cell will be replaced by another cell, e.g. because the serving satellite is subject to a feeder link switch, thereby starting to forward traffic to and from another gNB.

[0094] There are two main deployment principles for NTN: quasi-Earth-fixed cells and Earthmoving cells. These deployment principles are also referred to by other names. The quasi-Earth-fixed cells deployment principle is also referred to as quasi-Earth-fixed beams. The Earth-moving cells deployment principle is also referred to as Earth-moving beams, or shorter, moving or and moving beams.

[0095] “SSB” and “SS / PBCH” are two equivalent terms for the same thing. Both are used in the 3 GPP standard.

[0096] In this document, the satellites involved in a satellite switch with resync procedure are mostly referred to as the “old satellite” and the “new satellite”, but they may equivalently be referred to as the “source satellite” (equivalent term for the “old satellite”) and the “target satellite” (equivalent term for the “new satellite”).

[0097] Due to the special operating conditions in a Non-Terrestrial Network, the system information broadcasted in an NTN cell has to include NTN-specific information. To serve this purpose, a new SIB (SIB 19) has beenintroduced in NR NTN which contains NTN-specific information. In loTNTN, SIB31 more or less corresponds to SIB19 in NR NTN.

[0098] In 3GPP release 18, the feature satellite switch with resync was introduced with the goal to enable switching of the satellite that serves a certain quasi-Earth-fixed cell area with less control signaling involved than when handover or conditional handover is used to move the UEs to the new satellite, as was the case with 3GPP release 17 functionality, and with that legacy functionality, the new satellite would in principle serve a new cell, albeit covering the same area as the old cell (and hence the handover or conditional handover was needed). With satellite switch with resync, the physical cell identity (PCI) remains unchanged during the switch and the cell thus in principle remains the same from the UE perspective. This new functionality is only specified for intra-gNB cases, i.e. the same gNB communicates with the UEs via the old and the new satellite (in the transparent payload architecture).

[0099] Satellite switch with resync comes in two flavors: hard and soft. With the hard variant, the switch from the old to the new satellite happens instantaneously, i.e. without any overlapin time. In the case of transparent pay load architecture, the gNB thus starts transmitting via the new satellite immediately as it stops transmitting via the old satellite.

[0100] On the other hand, with soft satellite switch with resync, there is a period of overlap during which both the old and the new satellite serve the cell, although the service via the new satellite is limited to transmission of SSBs for the UEs to synchronize on until the old satellite stops serving the cell, at which point the new satellite assumes full service of the cell. To avoid interference between the SSBs transmitted via the new satellite and the SSBs transmitted via the old satellite, the SSBs transmitted via the new satellite can be time-shifted. This concept is depicted in Figure 3. A UE is informed of this time-shift via the ssb-TimeOffset field in SIB 19. The time-shift is in relation to the time domain structure of the radio interface, i.e. in terms of the frames, subframes and slots (and their numbers), which are aligned (and continuous) at the uplink time synchronization reference points (UTSRP) of the respective satellites (note that this may be at the gNB for both the old and the new satellite). However, the time difference between an SSB sent via the old satellite and the corresponding SSB sent via the new satellite will be different for different UEs in the cell, depending on their locations, This is because UEs in different locations will have different propagation delays both to the old and the new satellite.

[0101] Satellite switch with resync is described as follows in section 16.14.3.2.3 in 3GPP TS 38.300 NR; NR and NG-RAN Overall description; Stage-2 version 18.4.0:

[0102] Upon both hard and soft satellite switch over in the quasi-Earth fixed scenario with the same SSB frequency and the same gNB, the satellite switch with re-synchronization procedure is supported. The satellite switch with re-sync avoids a L3 mobility for UEs in the cell by maintaining the same PCI on the geographical area covered by quasi-Earth fixed beam.

[0103] For soft satellite switch over, the UE can start synchronizing with the target satellite before the source satellite ends to serve the cell. It is not required for the UE to be connected to source satellite when the UE switches to target satellite.

[0104] For hard satellite switch over, the UE can only start synchronizing with the target satellite after the switch to the target satellite is initiated.

[0105] When both CHO and Satellite switch with re-synchronization are configured, it is up to UE implementation which procedure to initiate, if both of them are triggered simultaneously.

[0106] For the re-synchronization to the target satellite, random access can be triggered by a PDCCH order via the target satellite.######## End of extract from section 16.14.3.2.3 of3GPP TS 38.300 vl8.4.0 ########

[0107] The Radio Resource Control (RRC) parameters most relevant for satellite switch with resync are included in SIB 19. These parameters are the ones indicated by underlined text (other text has been omitted for brevity - indicated by the square brackets) in the below extract from 3GPP TS 38.331 version 18.4.0.

[0108] ################ Start of extract from 3GPP TS 38.331 V18.4.0 ################

[0109]

[0110]

[0111]

[0112] ################ End of extract from 3GPP TS 38.331 V18.4.0 ################

[0113] Furthermore, the NTN-Config-rl7lE is defined as follows in ASN.l code in the same specification:

[0114]

[0115] "

[0116] "

[0117] "

[0118]

[0119]

[0120]

[0121] Furthermore, section 5.7.19 in 3GPP TS 38.331 version 18.4.0 contains some procedural logic describing a UE’s behavior during satellite switch with resync. The text from that section is inserted below.

[0122] ######### Start of extract from section 5.7.19 in 3GPP TS 38.331 V18.4.0 #########

[0123] A UE capable of hard satellite switch with re synchronization in RRC -CONNECTED initiates the procedure when SatSwitchWithReSync and t-Service are included in SIB 19.

[0124] Upon initiating the procedure, the UE shall:

[0125] l >if t-ServiceStart is included in SIB 19 and the UE supports soft satellite switch with resynchronization :

[0126] 2> start acquiring DL synchronization with the SpCell served by the satellite indicated by ntn- Config in SatSwitchWithReSync between the time indicated by t-ServiceStart and the time indicated by t-Service for the serving cell;

[0127] l >upon the time indicated by t-Service:

[0128] 2> stop timer T430 if running;

[0129] 2> inform lower layers that UL synchronisation is lost due to satellite switch with resynchronization;

[0130] 2> synchronise to the DL of the SpCell served by the satellite indicated by ntn-Config in SatSwitchWithReSync, if the UE has not previously synchronized to the DL of the SpCell; 2> start timer T430 with the timer value set to ntn-UlSyncValidityDuration from the subframe indicated by epochTime in ntn-Config in SatSwitchWithReSync;

[0131] 2> inform lower layers when UL synchronisation is obtained.

[0132] NOTE: UE should attempt to re-acquire SIB 19 after satellite switch with re synchronization. The exact time is left to UE implementation.

[0133] ######### End of extract from section 5.7.19 in 3GPP TS 38.331 V18.4.0 #########

[0134] A proposal that is being discussed in the work with release 19 of the 3GPP standard is that the time-shifted SSBs sent via the new satellite during a soft satellite switch with resync should be only temporary, i.e. when the overlap period ends (i.e. at the time indicated by t-Service in SIB19), the SSBs would be shifted back to their original position in the time structure. That is,the time-shift indicated by the field ssb-TimeOffset in SIB 19 would be temporary and apply only between the times indicated by t-ServiceStart and t-Service.

[0135] An SSB consists of a Primary Synchronization Signal (PSS), a Secondary Synchronization Signal (SSS) and a PBCH part, which contains the MIB (which is a part of the cell’s system information) and some additional PBCH payload bits which are not part of the MIB.

[0136] A gNB may transmit SSBs in groups, wherein such a group is referred to as an SS burst or an SS burst set. A motivation for this may be that the different SSBs in an SS burst are transmitted in different beams (thus concentrating the energy to increase the reach), wherein the beams together provide coverage for the entire cell.

[0137] According to the 3GPP standard, SSBs can only be placed in certain positions in the time domain. These positions follow certain patterns, which depend on the maximum number of SSBs that can be sent in an SS burst, and this maximum number in turn depends on the carrier frequency. The positions are usually referred to as candidate positions, since a network deployment may choose to use only a subset of the candidate positions. Each candidate position is associated with an SSB index. The pattern of candidate positions is always confined to a half-frame (i.e. the 5 first subframes of a frame or the 5 last subframes of a frame). To this end, clause 4.1 of 3GPP TS 38.213 NR; Physical layer procedures for control (Release 18) version 18.5.0 restricts where an SSB can be placed within a half-frame - for a given SSB index, there is only one allowed position.

[0138] Furthermore, SSBs are tightly coupled to the frame in which they are transmitted, in the sense that the PBCH transmission contains information related to the SFN of the frame in which the PBCH (which is part of the SSB) is transmitted. The MIB contains the 6 MSBs of the 10 bits in the SFN. The remaining 4 LSBs of the SFN are conveyed by PBCH payload bits which are not included in the MIB. Some of the non-MIB PBCH payload bits are encoded by the scrambling sequence used to scramble the PBCH.

[0139] Moreover, if the time-shift moves the SS burst to a frame with new SFN that has at least one of the 6 SFN MSBs in the MIB with another value than the SFN of the frame of the SS burst’s original position, then the SFN bits in the MIB are impacted and should be changed to reflect the new time domain position of the SSB. And since the rest of the SFN bits are included in the remaining PBCH payload bits, these bits will be affected as soon as the SS burst is shifted to a frame with a new SFN. In addition, one of the non-MIB PBCH payload bits is a half-frame indicator, which indicates whether the SSB (as well as the SS burst it belongs to) is sent in the first or the last half-frame of the frame. This bit is affected if the time-shift moves the SS burstfrom the first half-frame of a frame to the last half-frame of a frame, or vice versa, regardless of whether the frame is the same as before the time-shift or another frame.

[0140] The RRC specification, 3GPP TS 38.331 version 18.4.0, allows configuring ssb-TimeOffset with subframe granularity (0-159 subframes), where a subframe is 1 ms long. This fine granularity of the time-shift means that after the time-shift, an SS burst may have a position where it crosses a frame border or a half-frame border. This means that it becomes ambiguous which SFN - and / or which half-frame - to indicate in the PBCH transmission. For instance, if the SS burst in its new position crosses a frame border, should the SSBs indicate the SFN of the frame where the SS burst starts or the SFN of the frame where the SS burst ends? Or should the SSB(s) in the SS burst that is(are) sent in the first frame indicate the SFN of that frame while the remaining SSB(s) in the SS burst indicate the SFN of the second frame?

[0141] In these situations, the standardized rule stipulating certain allowed SSB positions within a half-frame for the SSBs in an SS burst would beviolated. In addition, if different SSBs in an SS burst indicate different SFNs, the standardized principle that all SSBs in an SS burst should have the same content - apart from the SSB index - would be violated.

[0142] To address the problems described previously, multiple partly inter-related solutions are provided with the present invention. They apply both to temporary and permanent shifting of the SSBs during soft satellite switch with resync, although some specific aspects mainly target temporary SSB shifting.

[0143] The tools that are used to address the problems comprise:

[0144] Restricting the granularity of the time-shifts of the SSBs to steps of halfframes (i.e. steps of 5 subframes) or even whole frames. This is only used in solution 1.

[0145] Time-shifting of SSBs.

[0146] Frequency-shifting of SSBs.

[0147] Unchanged SSB content (decoupled from the SSB location while shifted). Indication of “special” SSB, e.g. shifted SSB without associated SIB1. SSBs without PBCH.

[0148] The different solutions are:

[0149] Solution 1: Restricting the time shift granularity to steps of half-frames (or frames) as a way to avoid the problems described previously regarding violation of the principles for where in the time domain structure an SS bursts may be placed.Solution 2: Time-shifting with unchanged SSB content. The SSB is allowed to deviate from the specified time domain locations of the SS burst patterns and the SSB content is decoupled from the time domain location context where it is located. Instead, the SSB content remains unaffected by the timeshift and instead reflects the time domain context of the location it would have without a time-shift.

[0150] Solution 3: Frequency -shifting instead of time-shifting of SSBs. By using frequency-shifting instead of time-shifting, the shifted SSBs can adhere to the specified rules for where an SS burst may be located in the time domain structure, while still avoiding colliding SSB transmissions. The solution is fully resistant to potential issues associated with large cell sizes and short SSB periodicities, and ensures collision-free SSBs in all scenarios.

[0151] Solution 4: Network choice of time-shifting (e.g. as in solution 2 or solution 1) or frequency-shifting (e.g. as in solution 3) of SSBs.

[0152] Solution 5: Time-shifting and frequency -shifting of SSBs used in different scenarios, according to specifications in the standard. For instance, frequency-shifting (e.g. as in solution 3) could be specified to be used when the combination of SCS and transmission bandwidth of the CBW allows, while time-shifting (e.g. as in solution 2 or solution 1) when the combination of SCS and transmission bandwidth of the CBW does not allow frequencyshifting.

[0153] Solution 6: Combined time-shifting and frequency-shifting of SSBs. As one option, there is full separation in both the time domain and the frequency domain. As another option, full separation is needed only in the time domain, while the frequency shift need be no larger than to ensure that UEs performing initial cell search will not detect and receive the SSBs.

[0154] Solution 7: Using modified SSBs without PBCH during the overlap period (i.e. while SSBs are transmitted both via the old satellite and via the new satellite). This may be combined with time- and / or frequency-shifting, e.g. as in solutions 1-6. When the overlap period ends, the modified SSBs are turned into regular SSBs.

[0155] The different solutions are described in further detail below.Solution 1: Restricted time-shift granularity

[0156] To avoid at least some of the problems described previously, for example the deviation from standardized principles regarding the SSBs locations in the time domain structure, this solution proposes restricting the flexibility of the time-shifting to steps of half-frames (i.e. a time-shift would be an integer number ofhalf-frames), or, optionally allowing only time-shifts of an integer number of whole frames (where a frame consists of 10 subframes, while a halfframe consists of 5 subframes).

[0157] This can be achieved by redefining the ssb-TimeOffset field in SIB 19 to a range ofhalf-frames (or a range of frames) or, in other embodiments, introducing a new ssb-TimeOffsetRestricted field in SIB 19 which is defined as a range ofhalf-frames (or a range of frames). The latter could for example be realized as follows in ASN.l code (based on the ASN.l code for SIB19 in 3GPP TS 38.331 version 18.4.0) (additions are indicated with underlined text, omitted text for brevity is indicated by square brackets).

[0158]

[0159]

[0160] Using this solution, at least some of the problems of deviation from the principles of the locations of SSBs in the time domain structure as well as the problems of setting the PBCHcontent described above may be avoided. As one benefit of this, UEs detecting the SSBs during initial cell search (and other UEs) will find SSBs with a content harmonized with the time domain structure. However, UEs finding the SSBs during initial cell search may still be confused (which may lead to errors) because they may expect to find either an associated SIB1 or an additional Cell-Defining SSB (CD-SSB), depending on the values of the ssb-SubcarrierOffset and pdcch-ConfigSIBl fields in the MIB. This issue could potentially be mitigated by using a reserved codepoint in pdcch-ConfigSIBl. It would also be possible to prevent UEs from decoding the time-shifted SSBs by using an additional scrambling of the PBCH, e.g. applied to the CRC and / or on top of the normal scrambling. Legacy UEs would fail to decode this PBCH and non-legacy UEs (e.g. supporting release 19+ of the 3GPP standard) could know (by standard specification) to ignore SSBs scrambled in this way during initial cell search.

[0161] A disadvantage of this solution is that it restricts the flexibility of how the network can fine-tune the time-shift to ensure collision-free SSB transmissions in the entire cell (which is especially critical in large cells with short SSB periodicities). This may however not be a severe restriction in many cases, as the optimal time-shift typically would be half an SSB period. However, the problem may become more severe when the shortest SSB periodicity, i.e. 5 ms, is used.

[0162] Solution 2: Time-shifting with unchanged SSB content

[0163] With this solution, the SSB time-shifting configured by ssb-TimeOffset with a range of 1-159 subframes is still used, but to this is added the feature that the temporarily time-shifted SSB is allowed to be located in places that deviates from the locations and patterns stipulated by clause 4.1 in 3GPP TS 38.213 version 18.5.0, and is allowed have a content that deviates from the principles of how this content should be tied to the time domain structure. This allows to introduce a different principle for temporarily time-shifted SSBs, wherein the SSB content remains unchanged, unaffected by the time-shift. That is, the content of a time-shifted SSB is the content it would have without a time-shift, i.e. the content reflects the time domain position the SSB would have had without a time-shift (e.g. in terms of SFN and half-frame indications). A UE receiving it could thus use ssb-TimeOffsest to inverse the time-shift to determine the SSB’s permanent position in the time domain structure and interpret the SSB content (in particular the PBCH content) accordingly. (Alternatively, or as another option, the UE may ignore the content of the PBCH during the overlap period, i.e. while SSBs are transmitted both via the old satellite and via the new satellite).Note that since the scrambling sequence used to scramble the PBCH carries information constituting bits of the PBCH payload, unchanged SSB content (in particular unchanged PBCH content) means that the scrambling sequence applied to the PBCH remains unaffected by the time-shift, just like the rest of the SSB / PBCH content.

[0164] Solution 3: Frequency-shifting of SSBs

[0165] With this solution, no time-shift is applied to the SSBs, but instead the SSBs associated with the new satellite are shifted in the frequency domain (where this shift may be only temporarily applied during the time when SSBs are sent via both the old satellite (a.k.a. source satellite) and the new satellite (a.k.a. target satellite)). This is further depicted in Figure 4. This way, problems associated with time-shifting of SSBs described previously may be avoided. In addition, the solution mitigates potential issues associated with large cell sizes and short SSB periodicities, and ecan provide collision-free SSBs. As the ssb-SubcarrierOffset field is affected by the frequency -shift, this solution may be considered as two options: one where the ssb-SubcarrierOffset field reflects the SSB’s new position in the frequency domain, and one where the principle of unchanged SSB content is applied, so that it reflects the SSB’s unshifted position in the frequency domain.

[0166] To support this solution, a new field, e.g. called ssb-FrequencyOffset, could be introduced as an extension in SIB 19 to indicate the frequency-shift, e.g. in number of subcarriers or in steps of X Hz or steps of X kHz or steps of X MHz. If the new field indicates the frequency-shift in terms of number of subcarriers, as one option this could refer to the subcarrier spacing used for the SSBs or, as another option, it could refer to the subcarrier spacing indicated in the subCarrierSpacingCommon field in the MIB, or, as a yet another option, the new field could include, or be accompanied by, an indication of the subcarrier spacing to apply.

[0167] The following is an example of how this could be implemented in ASN.1 (based on the ASN.l code for SIB19 in 3GPP TS 38.331 version 18.4.0) (additions are indicated with underlined text, omitted text for brevity is indicated by square brackets)

[0168]

[0169]

[0170]

[0171] An additional benefit (at least when the frequency-shift is temporary) of this solution is that if the SSBs are shifted to a frequency which is not on the sync raster (which comprises the frequencies on which a UE searches for SSBs, e.g. during initial cell search), they will not be found by UEs performing initial cell search, in particular not legacy UEs, meaning that “accidental” camping on the frequency -shifted SSBs is avoided.

[0172] The applicability of the solution has the restriction that it requires that the total bandwidth (also referred to as transmission bandwidth within the carrier bandwidth (CBW)) has to be large enough to fit two non-overlapping SSBs in parallel. This means that the solution cannot be applied in deployments with certain combinations of subcarrier spacing (SCS) and transmission bandwidth of the carrier bandwidth (CBW). However, the range of deployment scenarios (i.e. combinations of SCS and CBW) in which the solution can be applicable can be extended to include also some of the more challenging combinations of SCS and transmission bandwidth of the CBW by using the punctured SSBs with narrower transmission bandwidth which 3GPP has specified for use in deployments with 3 MHz CBW. Preferably, such punctured SSBs would only be applied during the overlap period when SSBs are transmitted via both the old and the new satellite (and only when the combination of SCS and transmission bandwidth of the CBW requires it).

[0173] In a variation of this solution, the frequency-shifted SSB can be a Non-Cell-Defining SSB (NCD-SSB). For example, during the overlap period when SSBs are transmitted via both the old and the new satellite, a CD-SSB would correspond to the old satellite (source satellite) whereas a NCD-SSB would correspond to the new satellite (target satellite).

[0174] Solution 4: Network choice of time-shifted or frequency-shifted SSBsWith this solution, the standard would support both time-shifting and frequency-shifting of SSBs (but only one of them at a time), so that the network can choose to apply either of them (but not both) during a soft satellite switch with resync. The indication of the choice of type of shift, as well as the size of the shift, could e.g. be indicated in SIB 19, which then would have to be extended with field(s) supporting this possibility.

[0175] The following is an example of how this could be implemented in ASN.1 (based on the ASN.l code for SIB19 in 3GPP TS 38.331 version 18.4.0) (additions are indicated with underlined text, omitted text for brevity is indicated by square brackets)

[0176]

[0177]

[0178] The time-shifting referred to could, as one option, be time-shifting as described for solution 2 in section 2.7.1.2.2 (i.e. time-shifting with unchanged SSB content), or, as another option, it could refer to the time-shifting described for solution 1 in section 2.7.1.2.1 (i.e. timeshifting with restricted granularity). The frequency-shifting could be the frequency-shifting of solution 3 described in section 2.7.1.2.3.

[0179] Solution 5: Time-shifting and frequency-shifting of SSBs used in different scenariosWith this solution, the standard should support, and stipulate, both time-shifting of SSBs and frequency -shifting of SSBs, but in different scenarios, e.g. in network deployments with different combinations of SCS and transmission bandwidth of the CBW.

[0180] As one option, frequency-shifting, e.g. in accordance with solution 3 (described in section 2.7.1.2.3) could be specified to be used in all deployment scenarios where the combination of SCS and the transmission bandwidth of the CBW allows it, while time-shifting, e.g. in accordance with solution 2 (described in section 2.7.1.2.2) or in accordance with solution 1 (described in section 2.7.1.2.1). In one variant of this option, the scenarios where frequencyshifting of SSBs is stipulated include scenarios where the combination of SCS and transmission bandwidth of the CBW requires puncturing of SSBs (to make two non-overlapping parallel SSBs fit in the transmission bandwidth of the CBW). In another variant of this option, the scenarios where frequency-shifting of SSBs is stipulated exclude scenarios where the combination of SCS and transmission bandwidth of the CBW requires puncturing of SSBs (to make two non-overlapping parallel SSBs fit in the transmission bandwidth of the CBW), and in these scenarios, time-shifting of SSBs (e.g. in accordance with solution 2 or solution 1) would instead be stipulated.

[0181] The time-shift (when this is used) or the frequency-shift (when this is used) could be indicated in SIB 19.

[0182] Solution 6: Combined time-shifting and frequency-shifting of SSBs

[0183] With this solution, both time-shifting (e.g. in accordance with solution 2 or solution 1) and frequency-shifting of SSBs are applied simultaneously when SSBs are shifted.

[0184] In one variant of the solution, “full frequency-shifting” (i.e. with shifts large enough to allow two non-overlapping SSBs to fit within the transmission bandwidth of the CBW, even though this is not needed because the time-shift ensures that the SSBs are not parallel in the frequency domain).

[0185] In another variant, the time-shifting of the SSBs (e.g. in accordance with solution 2 or solution 1) is complemented by a frequency-shift that is smaller than what would be needed make the SSBs non-overlapping if they were transmitted (or received) in parallel. In this variant the frequency-shift can be almost arbitrarily small as long as it is large enough to prevent UEs performing initial cell search from detecting and receiving the SSBs. An additional requirement to achieve the purpose of preventing UEs from detecting and receiving the frequency-shifted SSBs during initial cell search is that the frequency of the frequency -shifted SSBs must deviate enough from the frequencies on the sync raster.The time-shift and the frequency-shift could both be indicated in SIB 19, but as another option, the frequency -shift could be specified in the standard (e.g. possibly with different shift sizes depending on the carrier frequency and / or the carrier bandwidth) while the time-shift is indicated in SIB 19.

[0186] Extensions to the solutions

[0187] As one possible solution extension, any or all of the above-described solutions could be extended with a possibility to indicate in the PBCH content (or PBCH scrambling) that the SSB is a special SSB, e.g. a time-shifted SSB or a frequency SSB. To this end, as one option, a reserved codepoint in pdcch-ConfigSIBl could be used to indicate the special nature of the SSB. As another option, the special nature of the SSB could be indicated by a modification of the scrambling applied to the PBCH, e.g. by applying additional scrambling to the PBCH, e.g. applied to the CRC and / or on top of the normal scrambling on the full PBCH.

[0188] As another possible solution extension, any or all of the above-described solutions could be used either with unchanged SSB content (applicable to all solutions) or with SSB content that reflects the shifted SSB’s new position in the time domain and / or frequency domain (not applicable to solution 2).

[0189] Solution 7: Shifted PSS / SSS without PBCH

[0190] With this solution, the SSBs transmitted via the new satellite are modified during the overlap period, so that they only consist of the PSS and SSS, but without any PBCH. This can be achieved e.g. through muting or puncturing PBCH within an SSB, where only the 127 subcarriers in the first and thirds symbols of the SSB would be preserved which correspond to PSS and SSS. This solution may be combined with time-shifting and / or frequency -shifting, e.g. in accordance with what is described for solutions 1-6.

[0191] When the overlap period ends, i.e. at t-Service (i.e. when the SSB transmissions, and other transmissions, via the old satellite cease), the SSBs are turned into full-fledged regular SSBs. If the time- and / or frequency -shift was temporary, the SSBs are also shifted back to the permanent position.

[0192] By removing the PBCH, the problems described previously regarding the violation of the coupling of the PBCH content with the time domain structure may be avoided by not transmitting any PBCH.

[0193] Figure 5 is a flow chart depicting an exemplary method performed by a wireless device or user equipment (UE). The method 500 is performed by a wireless device for switching between a first satellite serving a cell and a second satellite serving the cell. As describedpreviously the cell may be an earth fixed cell or quasi-earth fixed cell and from the wireless device’s perspective should be the same cell (same PCI) but as the serving satellites move the satellite serving the cell has to be switched over. The cell is comprised in a terrestrial footprint or spotbeam served by one or more satellite based radio access nodes. The wireless device is adapted for switching between a first satellite serving a cell and a second satellite serving the cell during a period of overlap. In other words the wireless device capable of receiving synchronization signal blocks, SSB’s, and system information blocks, SIBs, from both satellites serving the cell during the period of overlap. For example the SAN may be configured in transparent mode where one or more adaptive antenna systems (AAS) are satellite based and communicate with the terrestrial functions via a terrestrial gateway and connected via one or more feeder links or instances of a feeder link.

[0194] The method 500 proceeds with the step of receiving 510 a first satellite specific system information block, SIB, from the first satellite serving the cell, the SIB comprising subframe timing information for the cell. In some examples the subframe timing information comprises a timing offset for the SSB of the second satellite serving the cell, wherein the timing offset has a half-frame granularity. In other words, the wireless device receives in the first satellite specific SIB a timing offset for the SSB of the second satellite serving the cell, wherein the timing offset has a half-frame granularity. In other words the minimum offset value is a half frame.

[0195] When the wireless device determines that a switch to the second satellite serving the cell is to be performed, the method proceeds with the wireless device determining 520 a timing of a synchronization signal block, SSB for the second satellite serving the cell. The switch may be determined by receiving signalling to the wireless device by the serving cell or in another way, by the satellite serving the cell. In some examples the SSB from the second satellite serving the cell is distinguishable from an SSB from the first satellite serving the cell. The wireless device is performing a soft switch and therefore is receiving SSB’s and SIBs from both satellites serving ultimately the same cell. This is a temporary situation where there is an overlap of the beams transmitted by the source satellite and the target satellite.

[0196] The method proceeds 530 with the wireless device synchronizing with the second satellite serving the cell based on detecting the SSB corresponding to the second satellite serving the cell.

[0197] In some examples the timing offset comprises a restriction to an ssb-TimeOffset parameter signalled in the satellite specific SIB. In other examples a new parameter could besignalled. In some examples the new parameter may be added in a later release to restrict the timing to specific granularity.

[0198] In some examples the first satellite serving the cell is a source satellite and the second satellite serving the cell is a target satellite and both the first satellite and the second satellite are configured to operate with the same physical cell identity, PCI. In some examples the cell is an earth fixed cell, a quasi earth fixed cell or a earth moving cell.

[0199] In some examples the SSB from the second satellite serving the cell is temporarily distinguishable from the SSB of the first satellite serving the cell and receiving a subsequent SSB from the second satellite serving the cell which is no longer distinguishable from the SSB from the first satellite serving the cell.

[0200] In some examples the physical channel in which the SSB of the second satellite serving the cell is transmitted is scrambled according to a sequence identified in the first satellite specific SIB.

[0201] In some examples, distinguishing the SSB of the second satellite serving the cell from the SSB of the first satellite serving the cell involves the wireless device receiving, in the first satellite specific SIB a timing offset for the SSB of the second satellite serving the cell, wherein the timing offset is used only to indicate the timing of the SSB and the associated SSB content is configured according to the SSB timing without the offset.

[0202] In some examples, distinguishing the SSB of the second satellite serving the cell from the SSB of the first satellite serving the cell involves the wireless device receiving, in the first satellite specific SIB information indicating a frequency shift for the SSB of the second satellite serving the cell.

[0203] In some examples the information indicating the frequency shift for the SSB of the second satellite serving the cell is temporary and only applies when the SSB of the second satellite serving the cell is transmitted when the SSB of the first satellite serving the cell is still being transmitted.

[0204] In some examples the frequency shift is used only to distinguish the SSB of the second satellite serving the cell from the SSB of the first satellite serving the cell and the associated SSB content is configured according to the SSB frequency / subcarrier offset without the frequency shift.

[0205] In some examples the method further comprises the wireless device receiving, in the first satellite specific SIB an indication of whether a timing offset or a frequency shift is applied to the SSB from the second satellite serving the cell.In some examples the timing offset or a frequency shift is applied to the SSB from the second satellite serving the cell based on one or more scenarios or deployments, e.g. in network deployments with different combinations of subcarrier spacing, SCS, and transmission bandwidth of the carrier bandwidth, CBW.

[0206] In some examples both the timing offset and the frequency shift of embodiments 2a and 4 are applied to the SSB from the second satellite serving the cell.

[0207] In some examples both time-shift and the frequency -shift are indicated in the first satellite specific SIB.

[0208] In some examples the frequency -shift is pre-defined (e.g. with different shift sizes depending on the carrier frequency and / or the carrier bandwidth) and the time-shift is indicated in the first satellite specific SIB.

[0209] Figure 6 is a flow chart of an exemplary method performed by a network node. For example the network node may be a satellite access node (SAN).

[0210] The method 600 is performed by a network node for switching between a first satellite serving a cell and a second satellite serving the cell, wherein the cell is comprised in a terrestrial footprint served by one or more satellite based radio access nodes. The method 600 proceeds with the step of causing 610a transmission of a first satellite specific system information block, SIB, from the first satellite serving the cell, the SIB comprising subframe timing information for the cell. In some examples subframe timing information comprises a timing offset for a synchronization signal block, SSB, of the second satellite serving the cell, wherein the timing offset has a half-frame granularity. In other words, the network node causes the transmission in the first satellite specific SIB of a timing offset for the SSB of the second satellite serving the cell, wherein the timing offset has a half-frame granularity. In other words the minimum offset value is a half frame. In some examples this transmission is triggered by the onboard satellite functions. In other examples the terrestrial functions of the SAN trigger the transmission via control signalling.

[0211] The method proceeds with the network node causing 620 an indication to at least one served wireless device that a switch to the second satellite serving the cell is to be performed.

[0212] The method proceeds with the step of causing 630 a transmission of a synchronization signal block, SSB for the second satellite serving the cell, based on the indicated timing offset. In some examples the SSB from the second satellite serving the cell is distinguishable from an SSB from the first satellite serving the cell. In some examples this transmission is triggered bythe onboard satellite functions. In other examples the terrestrial functions of the SAN trigger the transmission via control signalling.

[0213] In some examples the timing offset comprises a restriction to an ssb-TimeOffset parameter signalled in the satellite specific SIB. In other examples a new parameter could be signalled. In some examples the new parameter may be added in a later release to restrict the timing to specific granularity. In some examples the first satellite serving the cell is a source satellite and the second satellite serving the cell is a target satellite and both the first satellite and the second satellite are configured to operate with the same physical cell identity, PCI..

[0214] In some examples the cell is an earth fixed cell, a quasi earth fixed cell or a earth moving cell.

[0215] In some examples the SSB from the second satellite serving the cell is temporarily distinguishable from the SSB of the first satellite serving the cell and causing the transmission of a subsequent SSB from the second satellite serving the cell which is no longer distinguishable from the SSB from the first satellite serving the cell.

[0216] In some examples the physical channel in which the SSB of the second satellite serving the cell is transmitted is scrambled according to a sequence identified in the first satellite specific SIB.

[0217] In some examples distinguishing the SSB of the second satellite serving the cell from the SSB of the first satellite serving the cell comprises causing the transmission, in the first satellite specific SIB a timing offset for the SSB of the second satellite serving the cell, wherein the timing offset is used only to indicate the timing of the SSB and the associated SSB content is configured according to the SSB timing without the offset.

[0218] In some examples distinguishing the SSB of the second satellite serving the cell from the SSB of the first satellite serving the cell comprises causing the transmission, in the first satellite specific SIB information indicating a frequency shift for the SSB of the second satellite serving the cell.

[0219] In some examples the information indicating the frequency shift for the SSB of the second satellite serving the cell is temporary and only applies when the SSB of the second satellite serving the cell is transmitted when the SSB of the first satellite serving the cell is still being transmitted.

[0220] In some examples the frequency shift is used only to distinguish the SSB of the second satellite serving the cell from the SSB of the first satellite serving the cell and the associatedSSB content is configured according to the SSB frequency / subcarrier offset without the frequency shift.

[0221] In some examples the method further comprises causing the transmission, in the first satellite specific SIB an indication of whether a timing offset or a frequency shift is applied to the SSB from the second satellite serving the cell.

[0222] In some examples the timing offset or a frequency shift is applied to the SSB from the second satellite serving the cell based on one or more scenarios or deployments, e.g. in network deployments with different combinations of subcarrier spacing, SCS, and transmission bandwidth of the carrier bandwidth, CBW.

[0223] In some examples both the timing offset and the frequency shift of embodiments 9a and 11 are applied to the SSB from the second satellite serving the cell.

[0224] In some examples both time-shift and the frequency -shift are indicated in the first satellite specific SIB.

[0225] In some examples the frequency -shift is pre-defined (e.g. with different shift sizes depending on the carrier frequency and / or the carrier bandwidth) and the time-shift is indicated in the first satellite specific SIB.

[0226] In some examples the network node is a satellite access network, SAN, comprising terrestrial based base station functions and non-terrestrial satellite based functions, e.g. adaptive antenna systems and payload transfer functions onboard the satellite.

[0227] In some examples the terrestrial functions of the SAN control the first and the second satellite based functions serving the cell.

[0228] Figure 7 shows an example of a communication system 700 in accordance with some embodiments.

[0229] In the example, the communication system 700 includes a telecommunications network 702 that includes an access network 704, such as a radio access network (RAN), and a core network 706, which includes one or more core network nodes 708. The access network 704 includes one or more access network nodes or base stations of various types, access network nodes 710A and 710B are depicted (which may be collectively referred to as network nodes 710), or any other similar 3rdGeneration Partnership Proj ect (3GPP) access nodes or non-3GPP access points (APs). Some embodiments of the access network 704 may include more than one access network technology. The network nodes 710 of access network 704 facilitate direct or indirect connection of wireless devices, also referred to as user equipment (UEs), such as byconnecting UEs 712A, 712B, 712C, and 712D (one or more of which may be generally referred to as UEs 712) to the core network 706 over one or more wireless connections.

[0230] Moreover, a network node is not necessarily limited to an implementation in which a radio portion and a baseband portion are supplied and integrated by a single vendor. Thus, it will be understood that network nodes include disaggregated implementations or portions thereof. For example, in some embodiments, the telecommunications network 702 includes one or more Open-RAN (ORAN) network nodes. An ORAN network node is a network node in the telecommunications network 702 that supports an ORAN specification (e.g., a specification published by the O-RAN Alliance, or any similar organization) and may operate alone or together with other network nodes to implement one or more functionalities of any network node in the telecommunications network 702, including one or more access network nodes 710 and / or core network nodes 708.

[0231] Examples of an ORAN network node include an open radio unit (O-RU), an open distributed unit (O-DU), an open central unit (O-CU), including an O-CU control plane (O-CU-CP) or an O-CU user plane (O-CU-UP), a RAN intelligent controller (near-real time or non-real time) hosting software or software plug-ins, such as a near-real time control application (e.g., xApp) or anon-real time control application (e.g., rApp), or any combination thereof (the adjective “open” designating support of an ORAN specification). An ORAN network node may support a specification by, for example, supporting an interface defined by the ORAN specification, such as an Al, Fl, Wl, El, E2, X2, Xn interface, an open fronthaul user plane interface, or an open fronthaul management plane interface. Moreover, an ORAN network node may be a logical node in a physical node. Furthermore, an ORAN network node may be implemented in a virtualization environment (described further below) in which one or more network functions are virtualized. For example, the virtualization environment may include an O-Cloud computing platform orchestrated by a Service Management and Orchestration Framework via an O-2 interface defined by the O-RAN Alliance or comparable technologies.

[0232] The network nodes 710 facilitate direct or indirect connection of one or more UEs 712 to the core network 706 over one or more wireless connections.

[0233] In some embodiments, the telecommunication network 702 includes a non-terrestrial network, NTN. Unless otherwise described herein, embodiments applicable for NTN may be implanted according to the following clauses. An NTN is telecommunication network where the radio access payload is conveyed via satellite to a ground station. E-UTRAN supports radioaccess over non-terrestrial networks for BL UEs, UEs in enhanced coverage and NB-IoT UEs. Support for non-terrestrial networks encompasses platforms that provide radio access through Geosynchronous orbits (GSO), Non-Geosynchronous Orbit (NGSO), which includes Low-Earth Orbit (LEO) and Medium Earth Orbit (MEO) or High Altitude Platform Systems (HAPS). Another example of a Non-Terrestrial Network (NTN) provides non-terrestrial NR access to the UE by means of an NTN payload and an NTN Gateway, a service link between the NTN payload and a UE, and a feeder link between the NTN Gateway and the NTN payload exists. An access network 704 may include an NTN access network such as the 3GPP Satellite Access Node (SAN) which comprises Non-NTN infrastructure base station functions (e.g. eNB / gNB) a terrestrial Gateway which provides the interface to the feeder link to an NTN payload RF node. In some embodiments a network node 710 comprises a SAN, wherein the location of base station functions for a network node 710 (described above for the general terrestrial access) vary between residing in the terrestrial access network node part of the SAN and the NTN Payload RF node functions depending on the supported architecture. One example of NTN architecture is called bent pipe or transparent architecture where the radio frequency processing function (transceiver) on a satellite platform is interconnected with a terrestrial base station, also known as transparent architecture, and the NTN payload is passed transparently, no unpacking. Another example of NTN architecture is called regenerative architecture, where part or all of the eNB / gNB can be in the satellite.

[0234] In some examples a SAN includes an open radio unit (O-RU), an open distributed unit (O-DU), an open central unit (O-CU), including an O-CU control plane (O-CU-CP) or an O-CU user plane (O-CU-UP), a RAN intelligent controller (near-real time or non-real time) hosting software or software plug-ins, such as a near-real time control application (e.g., xApp) or a non-real time control application (e.g., rApp), or any combination thereof (the adjective “open” designating support of an ORAN specification).

[0235] Example wireless communications over a wireless connection include transmitting and / or receiving wireless signals using electromagnetic waves, radio waves, infrared waves, and / or other types of signals suitable for conveying information without the use of wires, cables, or other material conductors. Moreover, in different embodiments, the communication system 700 may include any number of wired or wireless networks, network nodes, UEs, and / or any other components or systems that may facilitate or participate in the communication of data and / or signals whether via wired or wireless connections. The communication system 700may include and / or interface with any type of communication, telecommunication, data, cellular, radio network, and / or other similar type of system.

[0236] The UEs 712 may be any of a wide variety of communication devices, including wireless devices arranged, configured, and / or operable to communicate wirelessly with the network nodes 710 and other communication devices. Similarly, the network nodes 708, 710 are arranged, capable, configured, and / or operable to communicate directly or indirectly (e.g., via other devices of telecommunications network 702) with the UEs 712 and / or with other network nodes or equipment in the telecommunications network 702 to enable and / or provide network access, such as wireless network access, and / or to perform other functions, such as administration in the telecommunications network 702. More specifically, UEs 712 may send messages, data, and / or other signals to network nodes 708, 710 or other elements of the telecommunications network 702 by transmitting such signals to the relevant device directly without the signals passing through any intervening devices or by transmitting such signals to the relevant device indirectly through an intervening device (or multiple intervening devices) that then transmit the signal to the relevant device. Similarly, network nodes 708, 710 may send messages, data, and other signals to UEs 7122, other network nodes 708, 710, and other devices in telecommunications network 702 directly or indirectly. As one specific example, a core network node 108 may transmit a particular message to a UE 712 by transmitting the message to an access network node 710 that will then transmit the message to the intended UE 712. Similarly, a core network node 108 may receive a particular message from a UE 712 by receiving the message from an access network node 710 that itself received the message from the UE 712.

[0237] In the depicted example, the core network 706 connects elements of the access network 704 (e.g., one or more of the network nodes 710) to one or more host computing systems, such as host 716. These connections may be direct or indirect via one or more intermediary networks or devices. In other examples, network nodes may be directly coupled to hosts. The core network 706 includes one or more core network nodes (e.g., core network node 708) of various types, one or more of which may be generally referred to as network nodes 708. Network nodes 708 are structured with hardware and software components. Features of these components may be substantially similar to those described with respect to the UEs, access network nodes, and / or hosts, such that the descriptions thereof are generally applicable to the corresponding components of the core network node 708. Example core network nodes provide functions of one or more of a Mobile Switching Center (MSC), Mobility Management Entity (MME), HomeSubscriber Server (HSS), Access and Mobility Management Function (AMF), Session Management Function (SMF), Authentication Server Function (AUSF), Subscription Identifier De-concealing function (SIDF), Unified Data Management (UDM), Security Edge Protection Proxy (SEPP), Network Exposure Function (NEF), and / or a User Plane Function (UPF).

[0238] The host 716 may be under the ownership or control of a service provider other than an operator or provider of the access network 704 and / or the telecommunications network 702. The host 716 may be operated by the service provider or on behalf of the service provider. The host 716 may host a variety of applications to provide one or more service. Examples of such applications include live and pre-recorded audio / video content, data collection services such as retrieving and compiling data on various ambient conditions detected by a plurality of UEs, analytics functionality, social media, functions for controlling or otherwise interacting with remote devices, functions for an alarm and surveillance center, or any other such function performed by a server.

[0239] As a whole, the communication system 700 of Figure 7 enables connectivity between the UEs, network nodes, and hosts. In that sense, the communication system 700 may be configured to operate according to predefined rules or procedures, such as specific standards that include, but are not limited to: Global System for Mobile Communications (GSM); Universal Mobile Telecommunications System (UMTS); Long Term Evolution (LTE), and / or other suitable 2G, 3G, 4G, 5G standards, or any applicable future generation standard (e.g., 6G); wireless local area network (WLAN) standards, such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards (Wi-Fi); and / or any other appropriate wireless communication standard, such as the Worldwide Interoperability for Microwave Access (Wi-Max), Bluetooth, Z-Wave, Near Field Communication (NFC) ZigBee, Li-Fi, and / or any low-power wide-area network (LPWAN) standards such as LoRa and Sigfox. Moreover, the communication system 700 may be configured to support multiple different standards, protocols, or other rule sets, with individual components supporting all of the relevant rule sets or with different components or sub-systems within the communication system 700 supporting different standards, protocols, or rule sets.

[0240] As one example, in certain embodiments, access network 704 may contain some access network nodes 710 that support 3GPP radio access technologies (RAT), such as LTE or NR, while other access network nodes 710 support (or the same access network nodes 710 additionally support) non-3GPP RATs, such as Wi-Fi or a proprietary RAT. As another example, telecommunications network 702 may support multiple generations of relatedcommunication standards (e.g., 4G and 5G 3GPP communication standards) and, as a result, may include an access network 104 and / or a core network 106 that supports multiple different standard generations or may include multiple access networks 104 and / or multiple core networks 106 with individual networks 104, 106 supporting different standard generations.

[0241] Telecommunications network 702 may support network slicing to provide different logical networks to different devices that are connected to the telecommunications network 702. For example, the telecommunications network 702 may provide Ultra Reliable Low Latency Communication (URLLC) services to some UEs, while providing Enhanced Mobile Broadband (eMBB) services to other UEs, and / or Massive Machine Type Communication (mMTC)ZMassive loT services to yet further UEs.

[0242] In some examples, one or more of the UEs 712 are configured to transmit and / or receive information without direct human interaction. For instance, a UE may be designed to transmit information to the access network 704 on a predetermined schedule, when triggered by an internal or external event, or in response to requests from the access network 704. Additionally, a UE may be configured for operating in single- or multi-RAT or multi-standard mode. For example, a UE may operate with any one or combination of Wi-Fi, NR (New Radio) and LTE, i.e. being configured for multi-radio dual connectivity (MR-DC), such as E-UTRAN (Evolved-UMTS Terrestrial Radio Access Network) New Radio - Dual Connectivity (EN-DC).

[0243] In the example, the hub 714 communicates with the access network 704 to facilitate indirect communication between one or more UEs (e.g., UE 712C and / or 712D) and network nodes (e.g., network node 710B). In some examples, the hub 714 may be a controller, router, content source and analytics, or any of the other communication devices described herein regarding UEs. For example, the hub 714 may be a broadband router enabling access to the core network 706 for the UEs. As another example, the hub 714 may be a controller that sends commands or instructions to one or more actuators in the UEs. Commands or instructions may be received from the UEs, network nodes 710, or by executable code, script, process, or other instructions in the hub 714.

[0244] As another example, the hub 714 may be a data collector that acts as temporary storage for UE data and, in some embodiments, may perform analysis or other processing of the data. As another example, the hub 714 may be a content source. For example, for a UE that is a VR headset, display, loudspeaker or other media delivery device, the hub 714 may retrieve VR assets, video, audio, or other media or data related to sensory information via a network node, which the hub 714 then provides to the UE either directly, after performing local processing,and / or after adding additional local content. In still another example, the hub 714 acts as a proxy server or orchestrator for the UEs, in particular if one or more of the UEs are low energy loT devices.

[0245] The hub 714 may have a constant / persistent or intermittent connection to the network node 710B. The hub 714 may also allow for a different communication scheme and / or schedule between the hub 714 and UEs (e.g., UE 712C and / or 712D), and between the hub 714 and the core network 706. In other examples, the hub 714 is connected to the core network 706 and / or one or more UEs via a wired connection. Moreover, the hub 714 may be configured to connect to an M2M service provider over the access network 704 and / or to another UE over a direct connection. In some scenarios, UEs may establish a wireless connection with the network nodes 710 while still connected via the hub 714 via a wired or wireless connection. In some embodiments, the hub 714 may be a dedicated hub - that is, a hub whose primary function is to route communications to / from the UEs from / to the network node 71 OB. In other embodiments, the hub 714 may be a non-dedicated hub - that is, a device which is capable of operating to route communications between the UEs and network node 71 OB, but which is additionally capable of operating as a communication start and / or end point for certain data channels.

[0246] Figure 8 is another example of a communication system 800 according to some embodiments. As used herein, the communication system 800 includes multiple access points (APs) 810 (with four exemplary APs 810A, 810B, 810C, and 810D being depicted) and multiple wireless devices, referred to in the context of communication system 800 as stations (STAs) 812 (referred to individually as STA 812A, STA 812B, STA 812C, STA 812D, and STA 812E). STA 812A is served by AP 810A in a first basic service set (BSS) 820A. STA 810B and STA 810C are served by AP 810B in a second BSS, BSS 820B. STA 812D is served by AP 810C in a third BSS, BSS 820C. STA 812E is served by AP 810D in a fourth BSS, BSS 820D. Stations 812 may be non-AP STAs and correspond to various kinds of wireless devices, for example, user terminals, such as mobile or stationary computing devices like smartphones, laptop computers, desktop computers, tablet computers, gaming devices, head-mounted displays (HMDs) for Augmented Reality (AR) or Virtual Reality (VR), or the like. Further, stations 812 could, for example, correspond to other kinds of equipment like smart home devices, printers, multimedia devices, data storage devices, or the like.

[0247] Each of STAs 812 may connect through a radio link to one of APs 810. For example, depending on location or channel conditions experienced by a given STA 812, the STA mayselect an appropriate AP and BSS for establishing the radio link. The radio link may be based on one or more orthogonal frequency-division multiplexing (OFDM) carriers from a frequency spectrum that is shared on the basis of a contention-based mechanism, e.g., an unlicensed or license exempt band like 2.4 GHz Industrial, Scientific, and Medical (ISM) band, the 5 GHz band, the 6 GHz band, or the 60 GHz band.

[0248] Each AP 810 may provide data connectivity to STAs 812 connected to a particular AP 810. As illustrated, APs 810 may be connected to a data network 830. In this way, APs 810 may also provide data connectivity between STAs 812 and other entities, e.g., to one or more servers, service providers, data sources, data sinks, user terminals, or the like. Accordingly, the radio link established between a given STA 812 and its serving AP 810 may be used for providing various kinds of services to STA 812, e.g., a voice service, a multimedia service, or other data service. Such services may be based on applications that are executed on STA 812 and / or on a device linked to STA 812. By way of example, Figure 8 illustrates an application service platform 832 provided in data network 830. The application(s) executed on STA 812 and / or on one or more other devices linked to STA 812 may use the radio link for data communication with one or more other STA 812 and / or the application service platform 832, thereby enabling utilization of the corresponding service(s) at STA 812.

[0249] Figure 9 shows a wireless device 900, which may be configured to operate in communication system 700 of Figure 7 or in communication system 800 of Figure 8. The wireless device 900 may be alternatively referred to as a UE 900, like a UE 712 within the context of communication system 700, or as a station (STA) 900 or as a non-access-point station (non-AP STA) 900, like a STA 812 within the context of the communication system 800, in accordance with respective embodiments. As used herein, a wireless device refers to a device capable, configured, arranged and / or operable to communicate wirelessly with network nodes and / or other wireless devices. Examples of a wireless device include, but are not limited to, a smart phone, mobile phone, cell phone, voice over IP (VoIP) phone, wireless local loop phone, desktop computer, personal digital assistant (PDA), wireless cameras, gaming console or device, music storage device, playback appliance, wearable terminal device, wireless endpoint, mobile station, tablet, laptop, laptop-embedded equipment (LEE), laptop-mounted equipment (LME), smart device, wireless customer-premise equipment (CPE), vehicle, vehicle-mounted or vehicle embedded / integrated wireless device, and wireless terminal. Other examples include any type of UE identified by the 3rd Generation Partnership Project (3GPP),including a narrow band internet of things (NB-IoT) UE, a machine type communication (MTC) UE, and / or an enhanced MTC (eMTC) UE.

[0250] A wireless device 900 may support device-to-device (D2D) communication, for example by implementing a 3 GPP standard for sidelink communication, Dedicated Short-Range Communication (DSRC), vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), or vehicle-to-everything (V2X). In other examples, wireless device 900 may not necessarily have a user in the sense of a human user who owns and / or operates the relevant device. Instead, wireless device 900 may represent a device that is intended for sale to, or operation by, a human user but which may not, or which may not initially, be associated with a specific human user (e.g., a smart sprinkler controller). Alternatively, wireless device 900 may represent a device that is not intended for sale to, or operation by, an end user but which may be associated with or operated for the benefit of a user (e.g., a smart power meter).

[0251] In particular embodiments, wireless device 900 includes processing circuitry 902 that is operatively coupled via a bus 904 to an input / output interface 906, a power source 908, a memory 910, a communication interface 912, and / or any other component, or any combination thereof. Certain embodiments of wireless device 900 may include all or a subset of the components shown in Figure 9. The level of integration between the components may vary from one embodiment of wireless device 900 to another. In general, in a particular embodiment of wireless device 900, processing circuitry 902, input / output interface 906, power source 908, memory 910, and communication interface 912 may, in whole or in part, represent or include physical components common to or shared by one or more of the other elements of wireless device 900. Further, certain embodiments of wireless devices 900 may contain multiple instances of a component, such as multiple processors, memories, transceivers, transmitters, receivers, etc.

[0252] The processing circuitry 902 is configured to process instructions and data and may be configured to implement any sequential state machine operative to execute instructions stored as machine-readable computer programs in the memory 910. The processing circuitry 902 may be implemented as one or more hardware-implemented state machines (e.g., in discrete logic, field-programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), etc.); programmable logic together with appropriate firmware; one or more stored computer programs, general-purpose processors, such as a microprocessor or digital signal processor (DSP), together with appropriate software; or any combination of the above. For example, the processing circuitry 902 may include multiple central processing units (CPUs).In the example, the input / output interface 906 may be configured to provide an interface or interfaces to an input device, output device, or one or more input and / or output devices. Examples of an output device include a speaker, a sound card, a video card, a display, a monitor, a printer, an actuator, an emitter, a smartcard, another output device, or any combination thereof. An input device may allow a user to capture information into wireless device 900. Examples of an input device include a touch-sensitive or presence-sensitive display, a camera (e.g., a digital camera, a digital video camera, a web camera, etc.), a microphone, a sensor, a mouse, a trackball, a directional pad, a trackpad, a scroll wheel, a smartcard, and the like. The presence-sensitive display may include a capacitive or resistive touch sensor to sense input from a user. A sensor may be, for instance, an accelerometer, a gyroscope, a tilt sensor, a force sensor, a magnetometer, an optical sensor, a proximity sensor, a biometric sensor, etc., or any combination thereof. An output device may use the same type of interface port as an input device. For example, a Universal Serial Bus (USB) port may be used to provide an input device and an output device.

[0253] In some embodiments, the power source 908 is structured as a battery or battery pack. Other types of power sources, such as an external power source (e.g., an electricity outlet), photovoltaic device, or power cell, may be used to supply power to circuitry or to charge an associated battery. The power source 908 may further include power circuitry for delivering power from the power source 908 itself, and / or an external power source, to the various parts of wireless device 900 via input circuitry or an interface such as an electrical power cable. Power source 908 may perform any formatting, converting, or other modification to make accessible power suitable for the respective components of the wireless device 900 to which power is supplied.

[0254] The memory 910 may be or be configured to include memory such as random access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), magnetic disks, optical disks, hard disks, removable cartridges, flash drives, and so forth. In one example, the memory 910 includes one or more programs 914, such as an operating system, web browser application, a widget, gadget engine, or other application, and corresponding data 916. The memory 910 may store, for use by wireless device 900, any of a variety of various operating systems or combinations of operating systems.

[0255] The memory 910 may be configured to include a number of physical drive units, such as redundant array of independent disks (RAID), flash memory, USB flash drive, external harddisk drive, thumb drive, pen drive, key drive, high-density digital versatile disc (HD-DVD) optical disc drive, internal hard disk drive, Blu-Ray optical disc drive, holographic digital data storage (HDDS) optical disc drive, external mini-dual in-line memory module (DIMM), synchronous dynamic random access memory (SDRAM), external micro-DIMM SDRAM, smartcard memory such as tamper resistant module in the form of a universal integrated circuit card (UICC) including one or more subscriber identity modules (SIMs), such as a USIM and / or ISIM, other memory, or any combination thereof. The UICC may for example be an embedded UICC (eUICC), integrated UICC (iUICC) or a removable UICC commonly known as ‘SIM card.’ The memory 910 may allow wireless device 900 to access instructions, programs and the like, stored on transitory or non-transitory memory media, to off-load data, or to upload data. An article of manufacture, such as one utilizing a communication system may be tangibly embodied as or in the memory 910, which may be or comprise a device-readable storage medium.

[0256] The processing circuitry 902 may be configured to communicate with an access network or other network via or using the communication interface 912. The communication interface 912 may comprise one or more communication subsystems and may include or be communicatively coupled to an antenna 922. The communication interface 912 may include one or more transceivers used to communicate, such as by communicating with one or more remote transceivers of another device capable of wireless communication (e.g., another wireless device or a network node in an access network). Each transceiver may include a transmitter 918 and / or a receiver 920 appropriate to provide network communications (e.g., optical, electrical, frequency allocations, and so forth). Moreover, the transmitter 918 and receiver 920 may be coupled to one or more antennas (e.g., antenna 922) and may share circuit components, software or firmware, or alternatively be implemented separately.

[0257] In the illustrated embodiment, communication functions of the communication interface 912 may include cellular communication, Wi-Fi communication (e.g., according to an IEEE 802.11 family standard), LPWAN communication, data communication, voice communication, multimedia communication, short-range communications such as Bluetooth, near-field communication, location-based communication such as the use of the global positioning system (GPS) to determine a location, another like communication function, or any combination thereof. Communications may be implemented according to one or more communication protocols and / or standards, such as IEEE 802.11, Code Division Multiplexing Access (CDMA), Wideband Code Division Multiple Access (WCDMA), GSM, LTE, NewRadio (NR), UMTS, WiMax, Ethernet, transmission control protocol / intemet protocol (TCP / IP), synchronous optical networking (SONET), Asynchronous Transfer Mode (ATM), QUIC, Hypertext Transfer Protocol (HTTP), and so forth.

[0258] In particular embodiments, wireless device 900 may provide an output of data captured via a sensor, through its communication interface 912, via a wireless connection to a network node, and / or in any appropriate manner. Data captured by sensors of a wireless device 900 can be communicated through a wireless connection to a network node via another wireless device 900. In particular embodiments, such output may be periodic (e.g., once every 15 minutes if it reports the sensed temperature), random (e.g., to even out the load from reporting from several sensors), in response to a triggering event (e.g., when moisture is detected an alert is sent), in response to a request (e.g., a user initiated request), or a continuous stream (e.g., a live video feed of a patient).

[0259] As another example, wireless device 900 comprises an actuator, a motor, or a switch, related to a communication interface configured to receive wireless input from a network node via a wireless connection. In response to the received wireless input the states of the actuator, the motor, or the switch may change. For example, wireless device 900 may comprise a motor that adjusts the control surfaces or rotors of a drone in flight according to the received input or to a robotic arm performing a medical procedure according to the received input.

[0260] Wireless device 900, when in the form of an Internet of Things (loT) device, may be a device for use in one or more application domains, these domains comprising, but not limited to, wearable technology, extended industrial application and healthcare. Non-limiting examples of such an loT device are a device which is or which is embedded in: a connected refrigerator or freezer, a TV, a connected lighting device, an electricity meter, a robot vacuum cleaner, a voice controlled smart speaker, a home security camera, a motion detector, a thermostat, a smoke detector, a door / window sensor, a flood / moisture sensor, an electrical door lock, a connected doorbell, an air conditioning system like a heat pump, an autonomous vehicle, a surveillance system, a weather monitoring device, a vehicle parking monitoring device, an electric vehicle charging station, a smart watch, a fitness tracker, a wearable for tactile augmentation or sensory enhancement, a water sprinkler, an animal- or item-tracking device, a sensor for monitoring a plant or animal, an industrial robot, an Unmanned Aerial Vehicle (UAV), and any kind of medical device, like a heart rate monitor or a remote controlled surgical robot. In particular embodiments, wireless device 900 represents an loT device that comprises circuitry and / or software in dependence of the intended application of the loT devicein addition to other components as described in relation to the example embodiment of wireless device 900 shown in Figure 9.

[0261] As yet another specific example, in an loT scenario, wireless device 900 may represent a machine or other device that performs monitoring and / or measurements, and transmits the results of such monitoring and / or measurements to another wireless device and / or a network node. Wireless device 900 may in this case be an M2M device, which may in a 3GPP context be referred to as an MTC device. As one particular example, wireless device 900 may implement the 3GPP NB-IoT standard. In other scenarios, wireless device 900 may represent a vehicle, such as a car, a bus, a truck, a ship and an airplane, or other equipment that is capable of monitoring and / or reporting on its operational status or other functions associated with its operation.

[0262] In practice, any number of wireless devices 900 may be used together with respect to a single use case. For example, a first wireless device 900 might be or be integrated in a drone and provide the drone’s speed information (obtained through a speed sensor) to a second wireless device 900 that is a remote controller operating the drone. When a user makes changes from the remote controller, the first wireless device 900 may adjust the throttle on the drone (e.g. by controlling an actuator) to increase or decrease the drone’s speed. The first and / or the second wireless device 900 can also include more than one of the functionalities described above. For example, wireless device 900 might comprise the sensor and the actuator, and handle communication of data for both the speed sensor and the actuators.

[0263] Figure 10 shows a network node 1000 in accordance with some embodiments. As used herein, network node refers to equipment capable, configured, arranged and / or operable to communicate directly or indirectly with a UE and / or with other network nodes or equipment, in a telecommunications network. In accordance with respective embodiments, network node 1000 may be configured to operate in communication system 700 of Figure 7, like network nodes 708 or 710, or in communication system 800 of Figure 8, like an AP 810 or a station 812. Examples of network nodes include, but are not limited to, access points (APs) (e.g., radio access points), base stations (BSs) (e.g., radio base stations, Node Bs, evolved Node Bs (eNBs) and NR NodeBs (gNBs)), O-RAN nodes or components of an O-RAN node (e.g., O-RU, O-DU, O-CU), components of a satellite access network (SAN) (e.g, terrestrial base station, gateway, NTN payload RF function).

[0264] Network nodes 1000 may be categorized based on the amount of coverage they provide (or, stated differently, their transmit power level) and so, depending on the provided amount ofcoverage, may be referred to as femto base stations, pico base stations, micro base stations, or macro base stations. Network node 1000 may be a relay node or a relay donor node controlling a relay. Network nodes 1000 may also include one or more (or all) parts of a distributed radio base station such as centralized digital units, distributed units (e.g., in an O-RAN access node) and / or remote radio units (RRUs), sometimes referred to as Remote Radio Heads (RRHs). Such remote radio units may or may not be integrated with an antenna as an antenna integrated radio. Parts of a distributed radio base station may also be referred to as nodes in a distributed antenna system (DAS).

[0265] Other examples of network nodes 1000 include multiple transmission point (multi-TRP) 5G access nodes, multi-standard radio (MSR) equipment such as MSR BSs, network controllers such as radio network controllers (RNCs) or base station controllers (BSCs), base transceiver stations (BTSs), transmission points, transmission nodes, multi-cell / multicast coordination entities (MCEs), Operation and Maintenance (O&M) nodes, Operations Support System (OSS) nodes, Self-Organizing Network (SON) nodes, positioning nodes (e.g., Evolved Serving Mobile Location Centers (E-SMLCs)), and / or Minimization of Drive Tests (MDTs).

[0266] In particular embodiments, network node 1000 includes a processing circuitry 1002, a memory 1004, a communication interface 1006, and a power source 1008. In general, in a particular embodiment of network node 1000, processing circuitry 1002, memory 1004, communication interface 1006, and power source 1008 may, in whole or in part, represent or include physical components common to or shared by one or more of the other elements of network node 1000.

[0267] The network node 1000 may be composed of multiple distinct network entities (e.g., a NodeB entity and a RNC entity, or a BTS entity and a BSC entity, etc.), which may each have or utilize their own respective physical components. In certain scenarios in which the network node 1000 comprises multiple such entities (e.g., BTS and BSC), one or more of the separate entities may be shared among several network nodes. For example, a single RNC may control multiple NodeBs. In such a scenario, each unique NodeB and RNC pair, may in some instances be considered a single separate network node. In some embodiments, the network node 1000 may be configured to support multiple radio access technologies (RATs). In such embodiments, some components may be duplicated (e.g., separate memories 1004 or portions of memory 1004 for different RATs) and some components may be reused (e.g., a same antenna 1010 may be shared by different RATs). The network node 1000 may also include multiple sets of the various illustrated components for different wireless technologies integrated intonetwork node 1000, for example GSM, WCDMA, LTE, NR, Wi-Fi (e.g., according to an IEEE 802.11 family standard), Zigbee, Z-wave, LoRaWAN, Radio Frequency Identification (RFID) or Bluetooth wireless technologies. These wireless technologies may be integrated into the same or different chip or set of chips and other components within network node 1000.

[0268] The processing circuitry 1002 may comprise a combination of one or more of a microprocessor, controller, microcontroller, central processing unit, digital signal processor, application-specific integrated circuit, field programmable gate array, or any other suitable computing device, resource, or combination of hardware, software and / or encoded logic operable to provide, either alone or in conjunction with other components, such as the memory 1004, to provide network node 1000 functionality.

[0269] In some embodiments, the processing circuitry 1002 includes a system on a chip (SOC). In some embodiments, the processing circuitry 1002 includes one or more of radio frequency (RF) transceiver circuitry 1012 and baseband processing circuitry 1014. In some embodiments, the RF transceiver circuitry 1012 and the baseband processing circuitry 1014 may be on separate chips (or sets of chips), boards, or units, such as radio units and digital units. In alternative embodiments, part or all of RF transceiver circuitry 1012 and baseband processing circuitry 1014 may be on the same chip or set of chips, boards, or units.

[0270] The memory 1004 may comprise any form of volatile or non-volatile computer-readable memory including, without limitation, persistent storage, solid-state memory, remotely mounted memory, magnetic media, optical media, random access memory (RAM), read-only memory (ROM), mass storage media (for example, a hard disk), removable storage media (for example, a flash drive, a Compact Disk (CD) or a Digital Video Disk (DVD)), and / or any other volatile or non-volatile, non-transitory device-readable and / or computer-executable memory devices that store information, data, and / or instructions that may be used by the processing circuitry 1002. The memory 1004 may store any suitable instructions, data, or information, including a computer program, software, an application including one or more of logic, rules, code, tables, and / or other instructions capable of being executed by the processing circuitry 1002 and utilized by the network node 1000. The memory 1004 may be used to store any calculations made by the processing circuitry 1002 and / or any data received via the communication interface 1006. In some embodiments, the processing circuitry 1002 and memory 1004 is integrated.

[0271] The communication interface 1006 is used in wired or wireless communication of signaling and / or data with UEs, other network nodes, and / or any other network equipment. Inthe illustrated embodiment, communication interface 1006 comprises port(s) / terminal(s) 1016 to send and receive data, for example to and from a network over a wired connection. In particular embodiments, network node 900 may be capable of wireless communication and communication interface 1006 may also include radio front-end circuitry 1018 that may be coupled to, or in certain embodiments a part of, an antenna 1010. Particular embodiments of radio front-end circuitry 1018 include filter(s) 1020 and amplifier(s) 1022. The radio front-end circuitry 1018 may be connected to an antenna 1010 and processing circuitry 1002. The radio front-end circuitry may be configured to condition signals communicated between antenna 1010 and processing circuitry 1002. The radio front-end circuitry 1018 may receive digital data that is to be sent out to other network nodes or UEs via a wireless connection. The radio frontend circuitry 1018 may convert the digital data into a radio signal(s) having the appropriate channel and bandwidth parameters using a combination of filters 1020 and / or amplifiers 1022. The radio signal(s) may then be transmitted via the antenna 1010. Similarly, when receiving data, the antenna 1010 may collect radio signals which are then converted into digital data by the radio front-end circuitry 1018. The digital data may be passed to the processing circuitry 1002. In other embodiments, the communication interface may comprise different components and / or different combinations of components.

[0272] In certain alternative embodiments, network node 1000 may be capable of wireless communication but does not include separate radio front-end circuitry 1018, instead, the processing circuitry 1002 includes radio front-end circuitry and is connected to the antenna 1010. Similarly, in some embodiments, all or some of the RF transceiver circuitry 1012 is part of the communication interface 1006. In still other embodiments, the communication interface 1006 includes one or more ports or terminals 1016, the radio front-end circuitry 1018, and the RF transceiver circuitry 1012, as part of a radio unit (not shown), and the communication interface 1006 communicates with the baseband processing circuitry 1014, which is part of a digital unit (not shown).

[0273] The antenna 1010 may include one or more antennas, or antenna arrays, configured to send and / or receive wireless signals. The antenna 1010 may be coupled to the radio front-end circuitry 1018 and may be any type of antenna capable of transmitting and receiving data and / or signals wirelessly. In certain embodiments, the antenna 1010 is separate from the network node 1000 and connectable to the network node 1000 through one or more interfaces or ports.

[0274] The antenna 1010, communication interface 1006, and / or the processing circuitry 1002 may be configured to perform some or all of the receiving operations and / or obtainingoperations described herein as being performed by the network node 1000. Any information, data and / or signals may be received from a UE, another network node and / or any other network equipment. Similarly, the antenna 1010, the communication interface 1006, and / or the processing circuitry 1002 may be configured to perform some or all of the transmitting or sending operations described herein as being performed by the network node 1000. Any information, data and / or signals may be transmitted to a UE, another network node and / or any other network equipment.

[0275] The power source 1008 provides power to the various components of network node 1000 in a form suitable for the respective components (e.g., at a voltage and current level needed for each respective component). The power source 1008 may further comprise, or be coupled to, power management circuitry to supply the components of the network node 1000 with power for performing the functionality described herein. For example, the network node 1000 may be connectable to an external power source (e.g., the power grid, an electricity outlet) via an input circuitry or interface such as an electrical cable, whereby the external power source supplies power to power circuitry of the power source 1008. As a further example, the power source 1008 may comprise a source of power in the form of a battery or battery pack which is connected to, or integrated in, power circuitry. The battery may provide backup power should the external power source fail.

[0276] Embodiments of the network node 1000 may include additional components beyond those shown in Figure 10 for providing certain aspects of the network node’s functionality, including any of the functionality described herein and / or any functionality necessary to support the subject matter described herein. For example, the network node 1000 may include user interface equipment to allow input of information into the network node 1000 and to allow output of information from the network node 1000. This may allow a user to perform diagnostic, maintenance, repair, and other administrative functions for the network node 1000.

[0277] Figure 11 is a block diagram illustrating a virtualization environment 1100 in which functions implemented by some embodiments may be virtualized. In the present context, virtualizing means creating virtual versions of apparatuses or devices which may include virtualizing hardware platforms, storage devices and networking resources. As used herein, virtualization can be applied to any device described herein, or components thereof, and relates to an implementation in which at least a portion of the functionality is implemented as one or more virtual components. Some or all of the functions described herein may be implemented as virtual components executed by one or more virtual machines (VMs) implemented in oneor more virtual environments 1100 hosted by one or more of hardware nodes, such as a hardware computing device that operates as an access network node, UE, core network node, or host. Further, in embodiments in which a virtual node does not require radio connectivity (e.g., a core network node or host), then the node may be entirely virtualized. In some embodiments, the virtualization environment 1100 includes components defined by the O-RAN Alliance, such as an O-Cloud environment orchestrated by a Service Management and Orchestration Framework via an 0-2 interface.

[0278] Applications 1102 (which may alternatively be called software instances, virtual appliances, network functions, virtual nodes, virtual network functions, etc.) are run in the virtualization environment Q400 to implement some of the features, functions, and / or benefits of some of the embodiments disclosed herein.

[0279] Hardware 1104 includes processing circuitry, memory that stores software and / or instructions executable by hardware processing circuitry, and / or other hardware devices as described herein, such as a network interface, input / output interface, and so forth. Software may be executed by the processing circuitry to instantiate one or more virtualization layers 1106 (also referred to as hypervisors or virtual machine monitors (VMMs)), provide VM 1108A and VM 1108B (which may be collectively referred to as VMs 1108), and / or perform any of the functions, features and / or benefits described in relation with some embodiments described herein. The virtualization layer 1106 may present a virtual operating platform that appears like networking hardware to one or more of the VMs 1108.

[0280] The VMs 1108 comprise virtual processing, virtual memory, virtual networking or interface and virtual storage, and may be run by virtualization layer 1106. Different embodiments of the instance of a virtual appliance 1102 may be implemented on one or more of VMs 1108, and the implementations may be made in different ways. Virtualization of the hardware is in some contexts referred to as network function virtualization (NFV). NFV may be used to consolidate many network equipment types onto industry standard high volume server hardware, physical switches, and physical storage, which can be located in data centers, and customer premise equipment.

[0281] In the context of NFV, each of the VMs 1108 may be a software implementation of a physical machine that runs programs as if they were executing on a physical, non-virtualized machine. Each of the VMs 1108, and that part of hardware 1104 that executes that VM, be it hardware dedicated to that VM and / or hardware shared by that VM with others of the VMs, forms separate virtual network elements. Still in the context of NFV, a virtual network functionis responsible for handling specific network functions that run in one or more of the VMs 1108 on top of the hardware 1104 and corresponds to an application 1102.

[0282] Hardware 1104 may be implemented in a standalone network node with generic or specific components. Hardware 1104 may implement some functions via virtualization. Alternatively, hardware 1104 may be part of a larger cluster of hardware (e.g. such as in a data center or CPE) where many hardware nodes work together and are managed via management and orchestration 1110, which, among others, oversees lifecycle management of applications 1102. In some embodiments, hardware 1104 is coupled to one or more radio units that each include one or more transmitters and one or more receivers that may be coupled to one or more antennas. Radio units may communicate directly with other hardware nodes via one or more appropriate network interfaces and may be used in combination with the virtual components to provide a virtual node with radio capabilities, such as a radio access node or a base station. In some embodiments, some signaling can be provided with the use of a control system 1112 which may alternatively be used for communication between hardware nodes and radio units.

[0283] Although the computing devices described herein (e.g., UEs, network nodes, hosts) may include the illustrated combination of hardware components, other embodiments may comprise computing devices with different combinations of components. It is to be understood that these computing devices may comprise any suitable combination of hardware and / or software needed to perform the tasks, features, functions and methods disclosed herein. Determining, calculating, obtaining or similar operations described herein may be performed by processing circuitry, which may process information by, for example, converting the obtained information into other information, comparing the obtained information or converted information to information stored in the network node, and / or performing one or more operations based on the obtained information or converted information, and as a result of said processing making a determination. Moreover, while components are depicted as single boxes located within a larger box, or nested within multiple boxes, in practice, computing devices may comprise multiple different physical components that make up a single illustrated component, and functionality may be partitioned between separate components. For example, a communication interface may be configured to include any of the components described herein, and / or the functionality of the components may be partitioned between the processing circuitry and the communication interface. In another example, non-computationally intensive functions of any of such components may be implemented in software or firmware and computationally intensive functions may be implemented in hardware.In certain embodiments, some or all of the functionality described herein may be provided by processing circuitry executing instructions stored on in memory, which in certain embodiments may be a computer program product in the form of a non-transitory computer-readable storage medium. In alternative embodiments, some or all of the functionality may be provided by the processing circuitry without executing instructions stored on a separate or discrete device-readable storage medium, such as in a hard-wired manner. In any of those particular embodiments, whether executing instructions stored on a non-transitory computer-readable storage medium or not, the processing circuitry can be configured to perform the described functionality. The benefits provided by such functionality are not limited to the processing circuitry alone or to other components of the computing device, but are enjoyed by the computing device as a whole, and / or by end users and a wireless network generally.Example Embodiments

[0284] Example LA method performed by a wireless device for switching between a first satellite serving a cell and a second satellite serving the cell, wherein the cell is comprised in a terrestrial footprint served by one or more satellite based radio access nodes, the method comprising: receiving a first satellite specific system information block, SIB, from the first satellite serving the cell, the SIB comprising subframe timing information for the cell; upon determining that a switch to the second satellite serving the cell is to be performed, determining a timing of a synchronization signal block, SSB for the second satellite serving the cell such that the SSB from the second satellite serving the cell is distinguishable from an SSB from the first satellite serving the cell; synchronizing with the second satellite serving the cell based on detecting the SSB corresponding to the second satellite serving the cell.

[0285] Example la. The method of Example 1, wherein the first satellite serving the cell is a source satellite and the second satellite serving the cell is a target satellite.

[0286] Example lb. The method of Example 1 or la, wherein the cell is an earth fixed cell, a quasi earth fixed cell or a earth moving cell.

[0287] Example 2. The method of Example 1, la, or lb, wherein the SSB from the second satellite serving the cell is temporarily distinguishable from the SSB of the first satellite serving the cell and receiving a subsequent SSB from the second satellite serving the cell which is no longer distinguishable from the SSB from the first satellite serving the cell.

[0288] Example 2a. The method of Example 1 or 2, wherein distinguishing the SSB of the second satellite serving the cell from the SSB of the first satellite serving the cell comprises: receiving, in the first satellite specific SIB a timing offset for the SSB of the second satellite serving the cell, wherein the timing offset has a half-frame granularity.

[0289] Example 2b. The method of Example 2a, wherein the physical channel in which the SSB of the second satellite serving the cell is transmitted is scrambled according to a sequence identified in the first satellite specific SIB.

[0290] Example 3. The method of Example 1 or 2, wherein distinguishing the SSB of the second satellite serving the cell from the SSB of the first satellite serving the cell comprises: receiving, in the first satellite specific SIB a timing offset for the SSB of the second satellite serving the cell, wherein the timing offset is used only to indicate the timing of the SSB and the associated SSB content is configured according to the SSB timing without the offset.

[0291] Example 4. The method of Example 1, la, lb, or 2, wherein distinguishing the SSB ofthe second satellite serving the cell from the SSB of the first satellite serving the cell comprises: receiving, in the first satellite specific SIB information indicating a frequency shift for the SSB of the second satellite serving the cell.

[0292] Example 4a. The method of Example 4, wherein the information indicating the frequency shift for the SSB of the second satellite serving the cell is temporary and only applies when the SSB of the second satellite serving the cell is transmitted when the SSB of the first satellite serving the cell is still being transmitted.

[0293] Example 4b. The method of Example 4 or 4a, wherein the wherein the frequency shift is used only to distinguish the SSB of the second satellite serving the cell from the SSB of the first satellite serving the cell and the associated SSB content is configured according to the SSB frequency / subcarrier offset without the frequency shift.

[0294] Example 5. The method of Example 2a or 4, further comprising: receiving, in the first satellite specific SIB an indication of whether a timing offset or a frequency shift is applied to the SSB from the second satellite serving the cell.

[0295] Example 6. The method of Example 2a or 4, wherein the timing offset or a frequency shift is applied to the SSB from the second satellite serving the cell based on one or more scenarios or deployments, e.g. in network deployments with different combinations of subcarrier spacing, SCS, and transmission bandwidth of the carrier bandwidth, CBW.

[0296] Example 7. The method of Example 1, la, lb or 2, wherein both the timing offset and the frequency shift of Examples 2a and 4 are applied to the SSB from the second satellite serving the cell.

[0297] Example 7a. The method of Example 7, wherein both time-shift and the frequency -shift are indicated in the first satellite specific SIB.

[0298] Example 7b. The method of Example 7, wherein the frequency-shift is pre-defined (e.g. with different shift sizes depending on the carrier frequency and / or the carrier bandwidth) and the time-shift is indicated in the first satellite specific SIB.

[0299] Example 8. A method performed by a network node for switching between a first satellite serving a cell and a second satellite serving the cell, wherein the cell is comprised in a terrestrial footprint served by one or more satellite based radio access nodes, the method comprising: causing the transmission of a first satellite specific system information block, SIB, from the first satellite serving the cell, the SIB comprising subframe timing information for the cell; causing the indication to at least one served wireless device that a switch to the second satellite serving the cell is to be performed; causing the transmission of a synchronization signal block,SSB for the second satellite serving the cell such that the SSB from the second satellite serving the cell is distinguishable from an SSB from the first satellite serving the cell.

[0300] Example 8a. The method of Example 8, wherein the first satellite serving the cell is a source satellite and the second satellite serving the cell is a target satellite.

[0301] Example 8b. The method of Example 8 or 8a, wherein the cell is an earth fixed cell, a quasi earth fixed cell or a earth moving cell.

[0302] Example 9. The method of Example 8, 8a, or 8b, wherein the SSB from the second satellite serving the cell is temporarily distinguishable from the SSB of the first satellite serving the cell and causing the transmission of a subsequent SSB from the second satellite serving the cell which is no longer distinguishable from the SSB from the first satellite serving the cell.

[0303] Example 9a. The method of Example 8, 8a, 8b or 9, wherein distinguishing the SSB of the second satellite serving the cell from the SSB of the first satellite serving the cell comprises:

[0304] causing the transmission, in the first satellite specific SIB a timing offset for the SSB of the second satellite serving the cell, wherein the timing offset has a half-frame granularity.

[0305] Example 9b. The method of Example 9a, wherein the physical channel in which the SSB of the second satellite serving the cell is transmitted is scrambled according to a sequence identified in the first satellite specific SIB.

[0306] Example 10. The method of Example 8, 8a, 8b or 9, wherein distinguishing the SSB of the second satellite serving the cell from the SSB of the first satellite serving the cell comprises:

[0307] causing the transmission, in the first satellite specific SIB a timing offset for the SSB of the second satellite serving the cell, wherein the timing offset is used only to indicate the timing of the SSB and the associated SSB content is configured according to the SSB timing without the offset.

[0308] Example 11. The method of Example 8, 8a, 8b or 9, wherein distinguishing the SSB of the second satellite serving the cell from the SSB of the first satellite serving the cell comprises:

[0309] causing the transmission, in the first satellite specific SIB information indicating a frequency shift for the SSB of the second satellite serving the cell.

[0310] Example Ila. The method of Example 11, wherein the information indicating the frequency shift for the SSB of the second satellite serving the cell is temporary and only applies when the SSB of the second satellite serving the cell is transmitted when the SSB of the first satellite serving the cell is still being transmitted.

[0311] Example 1 lb. The method of Example 11 or 1 la, wherein the wherein the frequency shift is used only to distinguish the SSB of the second satellite serving the cell from the SSB of thefirst satellite serving the cell and the associated SSB content is configured according to the SSB frequency / subcarrier offset without the frequency shift.

[0312] Example 12. The method of Example 9a or 11, further comprising: causing the transmission, in the first satellite specific SIB an indication of whether a timing offset or a frequency shift is applied to the SSB from the second satellite serving the cell.

[0313] Example 13. The method of Example 9a or 11, wherein the timing offset or a frequency shift is applied to the SSB from the second satellite serving the cell based on one or more scenarios or deployments, e.g. in network deployments with different combinations of subcarrier spacing, SCS, and transmission bandwidth of the carrier bandwidth, CBW.

[0314] Example 14. The method of Example 8, 8a, 8b or 9, wherein both the timing offset and the frequency shift of Examples 9a and 11 are applied to the SSB from the second satellite serving the cell.

[0315] Example 14a. The method of Example 14, wherein both time-shift and the frequencyshift are indicated in the first satellite specific SIB.

[0316] Example 14b. The method of Example 14, wherein the frequency -shift is pre-defined (e.g. with different shift sizes depending on the carrier frequency and / or the carrier bandwidth) and the time-shift is indicated in the first satellite specific SIB.

[0317] Example 15. The method of any of Examples 8 to 14, wherein the network node is a satellite access network, SAN, comprising terrestrial based base station functions and nonterrestrial satellite based functions, e.g. adaptive antenna systems and payload transfer functions onboard the satellite.

[0318] Example 16. The method of claim 15, wherein the terrestrial functions of the SAN control the first and the second satellite based functions serving the cell.

[0319] Example 17. A wireless device, comprising: processing circuitry configured to perform any of the operations of any of the Examples 1-7; and a power source configured to supply power to the processing circuitry.

[0320] Example 18. A network node comprising: processing circuitry configured to perform any of the operations of any of the Examples 8-16; a power source circuitry configured to supply power to the processing circuitry.

[0321] Example 19. A wireless device comprising: one or more antennas; communication interface connected to the one or more antennas and to processing circuitry; the processing circuitry being configured to perform any of the operations of any of the Examples 1-7; an input interface connected to the processing circuitry and configured to allow input ofinformation into the UE to be processed by the processing circuitry; an output interface connected to the processing circuitry and configured to output information from the UE that has been processed by the processing circuitry; and a power source connected to the processing circuitry and configured to supply power to the UE.

[0322] Example 20. A satellite access node, SAN, comprising: one or more antennas, and payload transfer functions onboard one or more satellites; feeder link communication interface connected to the one or more antennas and to processing circuitry; the processing circuitry being configured to perform any of the operations of any of the Examples 8-16.

Claims

CLAIMS1. A method (500) performed by a wireless device for switching between a first satellite serving a cell and a second satellite serving the cell during a period of overlap, wherein the cell is comprised in a terrestrial footprint served by one or more satellite-based radio access nodes, and the wireless device capable of receiving synchronization signal blocks, SSB’s, and system information blocks, SIBs, from both satellites serving the cell during the period of overlap, the method comprising:receiving (510) a first satellite specific SIB, from the first satellite serving the cell, the SIB comprising subframe timing information, comprising a timing offset for the SSB of the second satellite serving the cell, wherein the timing offset has a half-frame granularity;upon determining that a switch to the second satellite serving the cell is to be performed, determining (520) a timing of a SSB for the second satellite serving the cell; and, synchronizing (530) with the second satellite serving the cell based on detecting the SSB corresponding to the second satellite serving the cell.

2. The method according to claim 1, wherein the timing offset comprises a restriction to an s sb -TimeOffset parameter signalled in the satellite specific SIB.

3. The method according to claim 1 or 2, wherein the first satellite serving the cell is a source satellite and the second satellite serving the cell is a target satellite and both the first satellite and the second satellite are configured to operate with the same physical cell identity, PCI.

4. The method according to any of claims 1 - 3, wherein the SSB from the second satellite serving the cell is temporarily distinguishable from the SSB of the first satellite serving the cell and receiving a subsequent SSB from the second satellite serving the cell which is no longer distinguishable from the SSB from the first satellite serving the cell.

5. The method according to any of claims 1 - 4, wherein the physical channel in which the SSB of the second satellite serving the cell is transmitted is scrambled according to a sequence identified in the first satellite specific SIB.

6. The method according to any of claims 1 - 5, wherein the timing offset is used only to indicate the timing of the SSB and the associated SSB content is configured according to the SSB timing without the offset.

7. The method according to any of claims 1 - 6, wherein the SSB of the second satellite serving the cell is distinguished from the SSB of the first satellite serving the cell by the first satellite specific SIB information indicating a frequency shift for the SSB of the second satellite serving the cell.

8. The method according to claim 7, wherein the information indicating the frequency shift for the SSB of the second satellite serving the cell is temporary and only applies when the SSB of the second satellite serving the cell is transmitted when the SSB of the first satellite serving the cell is still being transmitted.

9. The method according to claim 7 or 8, wherein the frequency shift is used only to distinguish the SSB of the second satellite serving the cell from the SSB of the first satellite serving the cell and the associated SSB content is configured according to the SSB frequency / subcarrier offset without the frequency shift.

10. The method according to claim 9, wherein the frequency -shift is pre-defined (e.g. with different shift sizes depending on the carrier frequency and / or the carrier bandwidth) and the time-shift is indicated in the first satellite specific SIB.

11. A method (600) performed by a network node for switching between a first satellite serving a cell and a second satellite serving the cell, wherein the cell is comprised in a terrestrial footprint served by one or more satellite based radio access nodes, the method comprising: causing (610) a transmission of a first satellite specific system information block, SIB, from the first satellite serving the cell, the SIB comprising subframe timing information comprising a timing offset for a synchronization signal block, SSB, of the second satellite serving the cell, wherein the timing offset has a half-frame granularity;causing (620) an indication to at least one served wireless device that a switch to the second satellite serving the cell is to be performed; and,causing (630) a transmission of an SSB for the second satellite serving the cell from thesecond satellite serving the cell, based on the indicated timing offset.

12. The method according to claim 11, wherein the timing offset comprises a restriction to an ssb-TimeOffset parameter signalled in the satellite specific SIB.

13. The method according to claim 11 or 12, wherein the first satellite serving the cell is a source satellite and the second satellite serving the cell is a target satellite and both the first satellite and the second satellite are configured to operate with the same physical cell identity, PCI.

14. The method according to any of claims 11 - 13, wherein the SSB from the second satellite serving the cell is temporarily distinguishable from the SSB of the first satellite serving the cell and causing the transmission of a subsequent SSB from the second satellite serving the cell which is no longer distinguishable from the SSB from the first satellite serving the cell.

15. The method according to any of claims 11 - 14, wherein the physical channel in which the SSB of the second satellite serving the cell is transmitted is scrambled according to a sequence identified in the first satellite specific SIB.

16. The method according to any of claims 11 - 15, wherein the timing offset is used only to indicate the timing of the SSB and the associated SSB content is configured according to the SSB timing without the offset.

17. The method according to any of claims 11 - 16, wherein the SSB of the second satellite serving the cell is distinguished from the SSB of the first satellite serving the cell by the first satellite specific SIB information indicating a frequency shift for the SSB of the second satellite serving the cell.

18. The method according to any of claims 11 - 17, wherein the information indicating the frequency shift for the SSB of the second satellite serving the cell is temporary and only applies when the SSB of the second satellite serving the cell is transmitted when the SSB of the first satellite serving the cell is still being transmitted.

19. The method of claim 17 or 18, wherein the wherein the frequency shift is used only to distinguish the SSB of the second satellite serving the cell from the SSB of the first satellite serving the cell and the associated SSB content is configured according to the SSB frequency / subcarrier offset without the frequency shift.

20. The method according to any of claims 17 - 19, wherein the frequency-shift is pre-defined (e.g. with different shift sizes depending on the carrier frequency and / or the carrier bandwidth) and the time-shift is indicated in the first satellite specific SIB.

21. The method according to any of claims 11 - 20, wherein the network node is a satellite access network, SAN, comprising terrestrial based base station functions and non-terrestrial satellite based functions, e.g. adaptive antenna systems and payload transfer functions onboard the satellite.

22. The method according to claim 21, wherein the terrestrial functions of the SAN control the first and the second satellite based functions serving the cell.

23. A wireless device (712, 812, 900) for switching between a first satellite serving a cell and a second satellite serving the cell, wherein the cell is comprised in a terrestrial footprint served by one or more satellite-based radio access nodes, the wireless device comprising: processing circuitry anda power source configured to supply power to the processing circuitry, the wireless device being configured to:receive a first satellite specific system information block, SIB, from the first satellite serving the cell, the SIB comprising subframe timing information, comprising a timing offset for the SSB of the second satellite serving the cell, wherein the timing offset has a half-frame granularity;determine that a switch to the second satellite serving the cell is to be performed and determine a timing of a SSB for the second satellite serving the cell; and,synchronize with the second satellite serving the cell based on detecting the SSB corresponding to the second satellite serving the cell.

24. The wireless device (712, 812, 900) of claim 23, further configured to perform any of themethods according to claims 2 to 10.

25. A network node (704, 820, 1000) for switching between a first satellite serving a cell and a second satellite serving the cell, wherein the cell is comprised in a terrestrial footprint served by one or more satellite based radio access nodes, the network node comprising processing circuitry anda power source circuitry configured to supply power to the processing circuitry, the network node being configured to:cause the transmission of a first satellite specific system information block, SIB, from the first satellite serving the cell, the SIB comprising subframe timing information comprising a timing offset for a synchronization signal block, SSB, of the second satellite serving the cell, wherein the timing offset has a half-frame granularity;cause an indication to at least one served wireless device that a switch to the second satellite serving the cell is to be performed; and,cause the transmission of an SSB for the second satellite serving the cell from the second satellite serving the cell, based on the indicated timing offset26. The network node (704, 820, 1000) of claim 25, further configured to perform any of the methods according to claims 12 -22.

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