Methods and apparatuses for providing a communication service on-demand via a non-terrestrial network

Abstract

Disclosed methods and apparatuses provide support for a communication service in a Narrowband Internet-of-Things (NB-IoT) context, where an NB-IoT non-terrestrial network (NTN) provides the service to particular user terminals (UTs) in an NB-IoT cell by dynamically allocating and beamforming non-anchor carriers, to provide localized beam coverage to the UTs.

Description

METHODS AND APPARATUSES FOR PROVIDING A COMMUNICATION SERVICE ON-DEMAND VIA A NON-TERRESTRIAL NETWORKTECHNICAL FIELD

[0001] Disclosed methods and apparatuses relate to providing a communication service on demand via a non-terrestrial network (NTN).BACKGROUND

[0002] Narrowband Internet of Things (NB-IoT) is a cellular-based radio access technology (RAT) standardized by the Third Generation Partnership Project (3 GPP) to support potentially large numbers of low-complexity, low-data-rate devices with extended coverage and long battery life. NB-IoT typically operates within a narrow 180 kHz carrier that can be deployed in-band within a Long Term Evolution / New Radio (LTE / NR) carrier, in the guard band, or as a standalone carrier. NB-IoT allows network operators to reuse existing licensed spectrum efficiently with the technology optimized for infrequent, small data transmissions such as meter readings, sensor reports, and simple control messages. NB-IoT also includes features such as power saving mode (PSM), extended discontinuous reception (eDRX), and coverage enhancement levels, to meet stringent energy and coverage requirements for weak signal levels characteristic of low power or indoor devices.

[0003] To increase capacity and flexibility beyond what a single narrowband carrier can provide, operators may deploy multi-carrier NB-IoT, in which multiple NB-IoT carriers are configured within the available spectrum. Multi-carrier NB-IoT includes an anchor carrier and one or more non-anchor carriers. The anchor carrier provides the essential signaling for initial access and mobility, including synchronization signals, broadcast system information, and often paging and random access resources. NB-IoT terminals typically camp on the anchor carrier to acquire system access information and the non-anchor carriers may be used for capacity expansion and load balancing, for example.

[0004] More recently, non-terrestrial networks (NTNs), such as satellite-based radio access networks, have been considered and standardized as a complement to terrestrial cellular infrastructure for providing NB-IoT coverage. NTN-based NB-IoT raises certain challenges, such as large propagation delays on the satellite-based links. A further key challenge is downlink (DL) power constraints onboard the satellite(s) used in the NTN. These and other challenges make it challenging to use NTN-based NB-IoT in certain service scenarios, such as where realtime data flows must be supported.SUMMARY

[0005] Disclosed methods and apparatuses provide support for a communication service in a Narrowband Intemet-of-Things (NB-IoT) context, where an NB-IoT non-terrestrial network (NTN) provides the service to particular user terminals (UTs) in an NB-IoT cell by dynamically allocating and beamforming non-anchor carriers, to provide localized beam coverage to the UTs. The beamformed non-anchor carriers thus provide hotspot service where needed within an overall service area of the NB-IoT cell, which itself is supported by an anchor carrier. For example, the communication service provided via hotspot allocation is a real-time service such as a voice service. The communication service(s) provided via dynamic hotspot allocation may be any type of service requiring Quality-of-Service (QoS) treatment or otherwise requiring semi- persistent grant scheduling to support flows. The NTN also may use a power-boosting technique to improve signal quality or link robustness of the non-anchor carriers.

[0006] One embodiment comprises a method of operation by an NTN with respect to a multi-carrier NB-IoT cell provided by the NTN. The method includes providing NB-IoT connectivity for the NB-IoT cell via an anchor carrier that carries synchronization signals and broadcast information for the NB-IoT cell, the anchor carrier being associated with an anchor beam that illuminates an overall service area of the NB-IoT cell. The method further includes providing, as part of the NB-IoT connectivity, a communication service to individual UTs within the overall service area, using dynamically activated non-anchor carriers and where each non- anchor carrier is associated with a corresponding non-anchor beam that illuminates a respective localized service area within the overall service area. In this respect, providing the communication service to any given UT in the overall service area comprises assigning the given UT to an existing non-anchor carrier provided that there is an existing non-anchor carrier associated with a respective localized service area that contains the given UT and further provided that that existing non-anchor carrier has remaining service capacity for supporting the given UT, and otherwise dynamically activating a new non-anchor carrier and a new associated non-anchor beam for serving the given UT.

[0007] A related embodiment comprises an NTN. The NTN includes a satellite configured to provide NB-IoT connectivity for an NB-IoT cell of the NTN via an anchor carrier that carries synchronization signals and broadcast information for the NB-IoT cell. The anchor carrier is associated with an anchor beam that illuminates an overall service area of the NB-IoT cell.

[0008] Communications processing circuitry of the NTN is configured to provide, as part of the NB-IoT connectivity, a communication service to individual UTs within the overall service area. The communication service is provided using dynamically activated non-anchor carriers, where each non-anchor carrier is associated with a corresponding non-anchor beam thatilluminates a respective localized service area within the overall service area. Such operation may be referred to as dynamic hotspot allocation. With respect to providing the communication service to any given UT in the overall service area, the communications processing circuitry is configured to assign the given UT to an existing non-anchor carrier provided that there is an existing non-anchor carrier associated with a respective localized service area that contains the given UT and further provided that that existing non-anchor carrier has remaining service capacity for supporting the given UT. Otherwise, the communications processing circuitry dynamically activates a new non-anchor carrier and a new associated non-anchor beam for serving the given UT.

[0009] Of course, the present invention is not limited to the above features and advantages. Indeed, those skilled in the art will recognize additional features and advantages upon reading the following detailed description, and upon viewing the accompanying drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure l is a block diagram of a non-terrestrial network (NTN) that provides Narrowband Intemet-of-Things (NB-IoT) connectivity, according to an example embodiment.

[0011] Figure 2 is a logic flow diagram of a method of operation by an NTN, according to an example embodiment.

[0012] Figures 3-7 are block diagrams of various arrangements in an NTN for dynamic beamforming, according to example embodiments.

[0013] Figure 8 is a block diagram of a satellite communications system configured for operation as an NTN, according to an example embodiment.

[0014] Figures 9 and 10 are diagram illustrating an advantageous transmit power control approach, according to an example embodiment.DETAILED DESCRIPTION

[0015] Figure 1 illustrates a Non-Terrestrial Network (NTN) 10 that is configured to provide a multi -carrier Narrowband Intemet-of-Things (NB-IoT) cell 12, which is represented in the diagram in terms of a geographic service area that includes a plurality of user terminals (UTs) 14, which comprise one or more types of NB-IoT devices. Example operations include the NTN 10 serving as an access network that communicatively couples individual UTs 14 to one or more devices or systems accessible via one or more external networks 16, such as the Internet. In an example, a ground network 18 of the communicatively couples the UTs 14 to one or various application servers 20 accessible via the external network(s) 16. The application server(s) 20support one or more machine-type-communication (MTC) services for example, although diverse services and service types may be provided and the NTN 10 includes features and operations for providing one or more types of communication services in a manner that advantageously combines beamforming with the multi-carrier aspects of the NB-IoT cell 12.

[0016] The NTN 10 includes a satellite 22 and provides NB-IoT connectivity for the NB-IoT cell 12 via an anchor carrier 30 that carries synchronization signals and broadcast information for the NB-IoT cell 12. The anchor carrier 30 is associated with an anchor beam 32 that illuminates the overall service area of the NB-IoT cell 12. Here, “beam” refers to directional signal transmission or reception. Either the satellite 22 or the ground network 18 includes radio base station functionality for generating cellular downlink (DL) signals for transmission to UTs 14 via the satellite 22 and for receiving and processing cellular uplink (UL) signals received from the UTs 14. Put simply, the satellite 22 provides an air interface that comports with the NB-IoT specifications.

[0017] As part of the NB-IoT connectivity, the NTN 10 provides a communication service to individual UTs 14 within the overall service area using dynamically activated non-anchor carriers 34. Each non-anchor carrier 34 is associated with a corresponding non-anchor beam 36 that illuminates a respective localized service area 38 within the overall service area. Each non- anchor beam 36 may be understood as providing localized “hotspot” coverage that can be optimized for support of the communication service.

[0018] Providing the communication service to any given UT 14 in the overall service area comprises, in one or more embodiments, assigning the given UT 14 to an existing non-anchor carrier 34 provided that there is an existing non-anchor carrier 34 associated with a respective localized service area 38 that contains the given UT 14 and further provided that that existing non-anchor carrier 34 has remaining service capacity for supporting the given UT 14, and otherwise dynamically activating a new non-anchor carrier 34 and a new associated non-anchor beam 36 for serving the given UT 14.

[0019] In one or more embodiments, the communication service in question is of a type that requires semi-persistent scheduling of NB-IoT resources in one or both of the uplink (UL) or downlink (DL) directions. In such cases, non-anchor carriers 34 may be reserved for such use, or at least the NTN 10 may prioritize such scheduling on non-anchor carriers 34 as compared to user-plane data transfers not associated with the communication service or service type in question. For example, the communication service is a real-time service, such as a voice service. Example voice services include Internet Multimedia System (IMS) voice service.

[0020] Consider a device-terminated example, where a remote device or system initiates the communication service towards any particular UT 14 operating in the overall service area. In thiscase, the NTN 10 initiates the communication service towards the particular UT 14, based on receiving incoming signaling from an external network requesting initiation of the communication service for the particular UT 14. Initiating the communication service includes the NTN 10 determining non-anchor carrier assignment information for the particular UT 14 and using the anchor carrier 30 to configure the particular UT 14 for operation on an assigned nonanchor carrier 34.

[0021] The anchor carrier 30 is the “main” narrowband frequency where UTs 14 first connect to the NTN 10, with the anchor carrier carrying key signaling used by UTs 14 to find the NB-IoT cell 12, synchronize with the NB-IoT cell 12, read broadcast / system information, and perform the initial uplink access to the NTN 10. Conversely, each non-anchor carrier 34 serves as an extra NB-IoT carrier that need not carry the synchronization and broadcast / system information carried on the anchor carrier 30, or at least not completely or with the same periodicity. By omitting some or all of the cell-signaling overhead borne on the anchor carrier 30, each non-anchor carrier 34 has comparatively more capacity for carrying user-plane data. The NTN 10 exploits such capacity in an advantageous approach that combines as needed (on- demand) non-anchor carrier activation and deactivation in combination with beamforming-based hotspot coverage, to provide one or more communication services to UTs 14.

[0022] In particular, conventional NB-IoT is not well adapted for the delivery of such services, because of the need for Quality-of-Service (QoS) treatment of the involved user-plane traffic. For example, voice or other real-time data services may have various QoS requirements, such as jitter or minimum bit rates, and may require what amounts to deterministic or semi- persistent resource scheduling to support periodic data transfers in the flow.

[0023] Each carrier (anchor or non-anchor) has its own associated uplink and downlink resources (time-frequency slots). As such, it should be understood that a UT 14 being served on the anchor carrier 30 will receive and / or transmit user-plane data on the time-frequency resources associated with the anchor carrier 30. Likewise, for a UT 14 being served on a non- anchor carrier 34, the UT 14 will receive and / or transmit user-plane data on the time-frequency resources associated with its assigned non-anchor carrier 34. A given UT 14 may of course receive or transmit user-plane data on the anchor carrier 30 and on one or more non-anchor carriers 34, although the data being sent or received on each carrier may belong to a different communication service or application.

[0024] With respect to any particular UT 14 initiating a communication service that is delivered by the NTN 10 using the described on-demand hotspot approach, the NTN 10 receives signaling from the particular UT 14 on the anchor carrier. The signaling indicates initiation of the communication service by the particular UT 14 and, in response, the NTN 10 determines non-anchor carrier assignment information for the particular UT 14 and uses the anchor carrier to configure the particular UT 14 for operation on an assigned non-anchor carrier. Of course, the NTN 10 may send or forward initiation signaling towards a targeted remote party, e.g., a “called” party in a case where the communication service is voice. In one or more embodiments, deviceterminated and device-originated calling uses Session Initiation Protocol (SIP) signaling.

[0025] An advantageous aspect of the hotspot approach is the ability of the NTN 10 to provide enhanced signal quality on the non-anchor carriers 34, at least in cases where a nonanchor carrier 34 is not fully loaded. For example, in one or more embodiments, the NTN 10 performs load-based power control for each existing non-anchor carrier 34 to maximize a Physical Resource Block (PRB) transmit power while maintaining an average Effective Isotropic Radiated Power (EIRP) below a maximum allowed average EIRP applicable to each existing non-anchor carrier 34.

[0026] In this way, for one or more particular communication services or types of communication services that require QoS treatment or otherwise have data scheduling requirements not well suited to the conventional non-flow approach of data transfers in NB-IoT, the use of hotspots provided where and when needed within the NB-IoT cell 12 offers significant advantages. Accordingly, the NTN 10 operates with respect to the overall service area comprising the NB-IoT cell 12 according to a “beamforming solution.” The beamforming solution comprises a plurality of beamforming weights that provide for formation of the anchor beam 32 and each existing non-anchor beam 36.

[0027] In association with dynamically activating a new non-anchor carrier 34, the NTN 10 updates the beamforming solution to account for the new non-anchor beam 36 associated with the new non-anchor carrier 34. Similarly, the NTN 10 deactivates an existing non-anchor carrier 34 responsive to no UT 14 illuminated by the corresponding non-anchor beam 36 being active with respect to the communication service(s) delivered via that non-anchor carrier 34, with the NTN 10 updating the beamforming solution to account for the deactivation.

[0028] The NTN 10 in one or more embodiments applies the beamforming solution in the ground network 18 of the NTN 10 — i.e., the NTN 10 in one or more embodiments is configured for ground based beamforming (GBBF). With GBBF in the forward direction, the cellular DL signals 24 are weighted on the ground and relayed to the UTs 14 via the satellite 22, and the beamforming solution is based on end-to-end channel estimates going from the transmission point(s) in the ground network 18 of the NTN 10. With GBBF in the return direction, the satellite 22 relays the cellular UL signals 42 received from the UTs 14 to reception point(s) in the ground network 18, and the beamforming solution is applied in the signal -processing domain.

[0029] In one or more other embodiments, the satellite 22 applies the beamforming solution. For example, the satellite has a phased array antenna with a plurality of antenna elements used in beamforming and it has a beamforming circuit onboard that applies the beam weights to the antenna element signals in the transmit or receive directions for transmit or receive beamforming. Of course, the disclosed techniques are not limited to beam realization via phased array antennas.

[0030] Even with the satellite 22 applying the beamforming solution, in one or more embodiments, the NTN 10 computes the beamforming solution in the ground network 18 and transmits the beamforming solution to the satellite 22 for onboard application. Of course, it should be understood that the beamforming solution may be updated on a periodic or as needed basis, such as by estimating the propagation channels on a recurring basis and updating the beamforming solution to account for channel conditions and, of course, dynamic activation or deactivation of non-anchor carriers 34.

[0031] In at least one embodiment, the satellite 22 is a geosynchronous satellite and the NB- loT cell 12 has a potentially large service area that provides what may be regarded as conventional or baseline NB-IoT connectivity over the entire service area. To that baseline NB- loT connectivity, the NTN 10 uses dynamically activated non-anchor carriers 34 / non-anchor beams 36 to add on-demand support to individual UTs 14 or clusters of UTs 14 for one or more communication services that involve QoS flows or otherwise require some form of real-time scheduling support.

[0032] Figure 2 illustrates a method 200 of operation of an NTN 10 consistent with the foregoing example details. The method 200 includes providing (Block 202) NB-IoT connectivity for the NB-IoT cell 12 via an anchor carrier 30 that carries synchronization signals and broadcast information for the NB-IoT cell 12, the anchor carrier 30 associated with an anchor beam 32 that illuminates an overall service area of the NB-IoT cell 12. Here, saying that the anchor carrier 30 is associated with (or corresponds to) the anchor beam 32 means that anchor-carrier signals are beamformed according to the anchor beam 32, where such beamforming is applied in the forward and / or return directions.

[0033] The method 200 further includes providing (Block 204), as part of the NB-IoT connectivity, a communication service to individual UTs 14 within the overall service area, using dynamically activated non-anchor carriers 34. Each non-anchor carrier is associated with (or corresponds to) a corresponding non-anchor beam 36 that illuminates a respective localized service area 38 within the overall service area. Here, saying that each non-anchor carrier 34 is associated with (or corresponds to) a non-anchor beam 36 means that the involved non-anchor- carrier signals are beamformed according to the non-anchor beam 36, where such beamformingis applied in the forward and / or return directions. In one or more embodiments, non-anchor beam 36 need not be uniform in size and may be determined based on the locations and spatial distributions of UTs 14 being served via non-anchor beams 36.

[0034] Providing the communication service to any given UT 14 in the overall service area comprises initiating the communication service for the given UT 14 (Block 206) and determining whether an existing non-anchor carrier 34 is available for serving the UT 14 (Block 208). An existing non-anchor carrier 34 is “available” if its associated non-anchor beam 36 illuminates the given UT 14 and if it has remaining service capacity for supporting the given UT 14. If there is an available existing non-anchor carrier 34 (YES from Block 208), the NTN 10 assigns (Block 210) the given UT 14 to that existing non-anchor carrier 34 for providing the communication service. If no existing non-anchor carrier 34 is available (NO from Block 208), the method 200 includes dynamically activating (Block 212) a new non-anchor carrier 34 and a new associated non-anchor beam 36 for serving the given UT 14. In one or more embodiments, the NTN 10 may limit the activation of new non-anchor carriers 34 subject to overall power considerations and / or beamforming limitations.

[0035] Figure 3 illustrates a GBBF example in a forward beamforming context. User traffic for the various UTs 14 flows into communications processing circuitry 40, which forms corresponding beam signals. As used herein, “processing circuitry” comprises fixed circuitry or programmatically configured circuitry, or a combination of both. Processing circuitry comprises, for example, one or more microprocessors, microcontrollers, Digital Signal Processors (DSPs), Field Programmable Gate Arrays (FPGAs), Complex Programmable Logic Devices (CPLDs), Application Specific Integrated Circuits (ASICs), or other digital processing logic. In at least one embodiment, the communications processing circuitry 40 comprises one or more microprocessors that are specially adapted to carry out the hotspot-related operations described herein, based on the execution of computer program instructions stored in one or more types of computer readable media included in or accessible to the microprocessor s).

[0036] Regarding hotspot operations and control logic, user traffic not involved with the communication service(s) provided via hotspot service (i.e., not provided via the on-demand non-anchor carriers 34 / non-anchor beams 36) is formed into a beam signal corresponding to the anchor carrier 30 / anchor beam 32. User traffic to be provided via one or more active hotspots is formed into respective beam signals corresponding to the non-anchor carriers 34 associated with those hotspots (the corresponding localized service areas 38). These beam signals are not themselves beamformed and instead carry the data targeted to the corresponding beams.

[0037] Beamforming circuitry 42 applies the current beamforming solution (sets of beam weights corresponding to the various beams to be formed) to the beam signals, to obtain one ormore pluralities of weighted signals. A beam weight calculation circuit 44 provides the beamforming solution based on channel estimates provided by a channel estimation circuit 46. The channel estimation circuit 46 receives, for example, channel feedback from respective ones of the UTs 14 in the NB-IoT cell 12 and computes updated channel estimates on an ongoing basis, with the beam weight calculation circuit 44 using the updated channel estimates to update the beamforming solution. Further, the communications processing circuitry 40 may provide the beam weight calculation circuit 44 with non-anchor beam configurations, such that the beamforming solution adapts for the activation or deactivation of non-anchor beams 36.

[0038] One or more gateway stations 48 transmit the weighted signals to the satellite 22 via one or more feeder links (each gateway station 48 has its own respective feeder link to the satellite 22). Although not shown, the gateway station(s) 48 may incorporate radio base station functionality or may be associated with a radio base station of the NTN 10.

[0039] The satellite 22 includes a feeder-link interface system 50 for receiving the feederlink transmissions from the participating gateway station(s) 48, and such an interface may be a radiofrequency (RF) antenna system or an optical transceiver arrangement, in dependence on whether the feeder links are RF or optical. Correspondingly, the gateway station(s) 48 may include an RF antenna system or an optical transceiver arrangement, to support feeder link communications with the satellite 22.

[0040] A payload 52 onboard the satellite 22 couples the feeder-link interface system 50 to a user-link antenna system 54, which transmits the signals received from the ground network 18 for formation of the various beams, including the anchor beam 32 and any currently active (existing) non-anchor beams 36. The payload 52 in one or more embodiments is a bent-pipe payload that includes electrical-domain transponders that perform no signal processing but may apply filtering, amplification, and frequency translation. The user-link antenna system 54 comprises, for example, a plurality of antenna elements such that the transmission of weighted signal copies from the plurality of antenna elements creates constructive and destructive patterns of signal interference for far-field formation of the beams.

[0041] Figures 4 and 5 provide further example details for implementation of beamforming circuitry, such as the beamforming circuitry 42 depicted in Figure 3. Figure 4 relates to beamforming in the forward direction for an example “Beam A” where “A’ denotes any given beam to be form in the forward direction. The Beam Signal A comprises, for example, an intermediate frequency (IF) signal carrying user traffic for UTs 14 that are illuminated by Beam A, and a beamforming circuit 60 includes a signal splitter 62 that splits Beam Signal Ainto multiple signal copies. There are as many copies as there are transmission points / elements used in the beamforming and a signal weighting circuit 64 applies beam weights for Beam A to thesignal copies to obtain a set of weighted signals for formation of Beam X. The beam weights comprise, for example, a vector of complex coefficients that control the amplitude and phase of each signal copy with respect to its transmission from a respective one of the involved transmission points / elements.

[0042] Figure 5 illustrates example details for return (reception) beamforming via a beamforming circuit 70, to obtain a Beam signal T that corresponds to a return Beam T that illuminates a particular geographic area, which may be the overall service area of the NB-IoT cell 12 or a localized service area 38 therein. There is a plurality of reception points or antenna elements used for receiving transmissions from the UTs 14 operating in the overall service area of the NB-IoT cell 12. Each such received signal is weighted by signal weighting circuit 72 using a respective weight in a set of beam weights calculated for formation of Beam Y. A signal combiner 74 combines the weighted signals output from the signal weighting circuit 72 to obtain the Beam Signal Y. In an example case where Beam Signal Y corresponds to a given non-anchor beam 36, it will be appreciated that the incoming received signals comprise superpositions of uplink signals from multiple UTs 14 inside and outside the localized service area 38 of the given non-anchor beam 36. However, the beam weights are calculated such that the signal combining by the signal combiner 74 increases the signal-to-interference-and-noise ratio (SINR) of the uplink signals originating from UTs 14 within the localized service area 38 illuminated by the given non-anchor beam 36.

[0043] Figure 6 illustrates an example implementation of onboard beamforming at the satellite 22, where the satellite 22 includes beamforming circuitry 80, such as previously described, but where the ground network 18 includes a beam weight calculation circuit 82 to compute the beamforming solution. Thus, the feeder link(s) between the ground network 18 and the satellite 22 carry user traffic, control signaling, and the beamforming solution. The beamforming solution may be transmitted on a recurring basis, to reflect changing channel conditions and / or beam configurations.

[0044] Figure 7 illustrates an example where the satellite 22 includes the beamforming circuitry 80 and the beam weight calculation circuit 82. In this case, the ground network 18 does not provide the beamforming solution to the satellite 22 and instead provides the satellite 22 with beam configuration information, reflecting ongoing decisions by the ground network 18 regarding dynamic activation / deactivation of non-anchor beams 36 and corresponding beam information.

[0045] Broadly, in one or more embodiments, an NTN 10 includes a satellite 22 and is configured to provide NB-IoT connectivity for an NB-IoT cell 12 of the NTN 10. Such connectivity is provided via an anchor carrier 30 that carries synchronization signals andbroadcast information for the NB-IoT cell 12, where the anchor carrier 30 is associated with an anchor beam 32 that illuminates an overall service area of the NB-IoT cell 12.

[0046] The NTN 10 includes communications processing circuitry 40 that is configured to provide, as part of the NB-IoT connectivity, a communication service to individual UTs 14 within the overall service area. The NTN 10 provides the communication service using dynamically activated non-anchor carriers 34, where each non-anchor carrier 34 is associated with a corresponding non-anchor beam 36 that illuminates a respective localized service area 38 within the overall service area. Of course, it should be understood that the communication service itself may involve third parties and / or devices or systems outside the NTN 10, such that the communications processing circuitry 40 “provides” the communication service in the sense that it provides communicatively coupling to devices or system that originate the service and in the sense that it controls hotspot activation for providing the communication service to respective UTs 14.

[0047] With respect to providing the communication service to any given UT 14 in the overall service area, the communications processing circuitry 40 is configured to assign the given UT 14 to an existing non-anchor carrier 34 provided that there is an existing non-anchor carrier 34 associated with a respective localized service area 38 that contains the given UT 14 and further provided that that existing non-anchor carrier 34 has remaining service capacity for supporting the given UT 14. Otherwise, the communications processing circuitry 40 initiates dynamic activation of a new non-anchor carrier 34 and a new associated non-anchor beam 36 for serving the given UT 14.

[0048] Note that non-overlapping non-anchor carriers 34 may use the same carrier frequency and / or signal polarizations, while overlapping non-anchor carriers 34 are differentiated in terms of frequency, polarization, or time. In an example case, there are too many UTs 14 clustered together for providing the communication service via one non-anchor carrier 34, so overlapping non-anchor beams 36 may be used.

[0049] Among their various advantages, the disclosed techniques address or accommodate power constraints typical for satellite-based service, whereby satellite payloads are typically designed to a strict power delivery budget and may provide a total power capacity that is lower than what would be theoretically required to serve a full service or coverage area offered by the satellite. Moreover, satellite systems may also be limited in terms of frequency or physical processing resources. The on-demand hotspot service techniques disclosed herein address these and other issues and, notably, support targeted delivery of one or more types of communications services, such as services requiring semi-persistent resource scheduling or otherwise involving real-time data flows with QoS requirements. In one or more embodiments, the NTN 10 useshotspots within an NB-IoT coverage area to provide bidirectional voice communication. One or more such embodiments employ a GBBF architecture. While the beams are projected on the Earth by the satellite, the actual signal processing to form the beams is performed in the ground network. This approach reduces complexity of the satellite payload while allowing for the possibility of producing thousands of beams of various shapes and sizes, geographic coverage and gain, thus increasing overall capacity by placing beams according to localized demands.

[0050] Figure 8 provides a high-level block diagram of an overall satellite communications system (SCS) 100 that includes NTN infrastructure and certain core-network entities that provide NB-IoT connectivity over an NB-IoT cell 12, consistent with the foregoing example details. The SCS 100 may be understood as illustrating further details for the ground network 18 shown in Figure 1. That is, the NTN 10 introduced in Figure 1 may be realized in the context of the illustrated SCS 100. Note, too, that Figure 8 does not illustrate the satellite 22 used to provide NB-IoT coverage.

[0051] In at least one example embodiment, the communication service provided via hotspot management is a voice application. For example, one or more UTs 14 execute a voice application, with the SCS 100 providing NB-IoT connectivity and hotspot management to support the voice application.

[0052] A satellite global resource management (SGRM) 102 resides in a core network of the SCS 100 and it is configured to manage power and bandwidth for a satellite 22 that is used to provide NB-IoT connectivity for an NB-IoT cell 12. The satellite 22 also may be used for communications other than NB-IoT. The SGRM 102 maintains a global data base of satellite resources and all potential beam configurations and their states and for arbitrating available resources among various services, based on a set of rules. The SGRM 102 also configures a GBBF system 104 to generate beams with the desired characteristics (beam size, beam location, frequency, power level, etc.) at the appropriate time instant via a GBBF management interface (GMI).

[0053] Infrastructure associated with providing the NB-IoT connectivity include a resource management interface (RMI) node 106 to interface the radio base station 108 with the SGRM 102. The RMI node 106 operates a proxy server / interpreter to abstract out the details of an SRM Application Programming Interface (API) from an NB-IoT radio base station 108, e.g., an eNB. The RMI node 106 receives resource requests from the radio base station 108 according to an internal protocol and translates them to the SRM API and vice versa. Note that the example of Figure 8 assumes a bent-pipe satellite configuration and the radio base station 108 will be understood as transmitting / receiving NB-IoT DL / UL signals to / from a satellite. For example,the radio base station 108 interfaces with the satellite via one or more gateway stations 48 of the SCS 100, wherein the involved feeder link(s) convey the NB-IoT DL / UL signals.

[0054] The GBBF system 104 may be located at a gateway station 48 or may be centralized with respect to multiple gateway stations 48. In example operation, the GBBF system 104 interfaces with the RF front-end to access the forward signals and return signals carried over the feeder link and performs signal processing on these signals to form the beams toward the user locations. Although the current NB-IoT standard may not support voice, the disclosed techniques provide support for voice. In particular, the RMI node 106 can negotiate with the SGRM 102 for additional non-anchor carriers 34 to support voice per voice traffic demands in a real-time manner. In one such embodiment, the RMI node 106 receives requests from UTs 14 and corresponding requests the SGRM 102 to create new non-anchor beams 36 via the GBBF system 104 (assuming a new beam is needed), or to create additional channels on an existing non-anchor carrier 34 / beam 36 to support the requests. The RMI node 106 also cooperates with the SGRM 102 for release of non-anchor carriers 34 / beams 36 when they are no longer needed.

[0055] Consider an example of dynamic allocation of a non-anchor carrier 34. A UT 14 camps on the anchor carrier 30 during an idle state and stays on the anchor carrier 30 even when in a connected state during a data transmission. However, when a request for a call arrives, the radio base station 108 determines whether a non-anchor carrier 34 already exists at the UT 14 location and has adequate capacity to support the additional call. In the case, where the channel capacity is not adequate to support an additional call, or where no non-anchor carrier 34 exists at the location of the UT 14, the radio base station 108 sends a beam, bandwidth and carrier power request to the SGRM 102 via the RMI node 106.

[0056] The SGRM 102 allocates a non-anchor carrier 34 as solicited by the radio base station 108, based on availability of spectrum and power to support the call, and conveys the information to the radio base station 108 via the RMI node 106. The GBBF system 104 corresponding creates the associated non-anchor beam 34 to “host” the new non-anchor carrier 34. Here, “host” refers to the application of beamforming to the non-anchor carrier, for formation of the non-anchor beam 34. This beam may have different properties than the beam hosting the anchor carrier 30. For example, the anchor carrier 30 may be on an anchor beam 32 with a wide footprint supporting the camping of many UEs, while each non-anchor carrier 34 may be on a narrow spot beam oriented towards the location of a particular voice user. When calls are completed and the non-anchor carrier(s) 34 are no longer needed, radio base station 108 signals the SGRM 102 to deallocate the resources.

[0057] In one or more embodiments, each non-anchor carrier 34 is associated with a dynamically assigned non-anchor beam 36 and a dynamically assigned channel (frequency). Thisapproach avoids dedicating specific spectrum for anticipated voice calls all the time, and consuming valuable resources. Multiple calls can share a non-anchor carrier 34 as NB-IoT physical layers operate according to orthogonal frequency division multiple access (OFDMA) on the forward link and according to discrete Fourier transform spread frequency division multiple access (DFT-S-FDMA) on the return link. If another call comes in while an active call is taking place on a non-anchor carrier 34, the radio base station 108 may assign the new call on the same non-anchor carrier 34, if there are enough resources on it to carry additional calls. The non- anchor beams 36 may be allocated with a finite time limit if needed, based on existing business rules including interference and power coordination agreements. A mechanism to drive to power levels over a finite time limit to further this aim is described below

[0058] One or more embodiments of the SCS 100 use dynamic power adjustment based on channel utilization. In the DL direction, average satellite EIRP for each non-anchor carrier 34 must not exceed a threshold granted by the SGRM 102. At the same time, it is desired to maximize signal to noise ratio to the UT(s) 14 served by the non-anchor carrier 34. By factoring in the utilization factor, the radio base station 108 can boost power in active slots, while still keeping average power under a maximum threshold, as described below. As noted, in NB-IoT, in the DL direction, each PRB is 180 kHz x 1 ms. Each subframe is 10 ms long.

[0059] An example voice coder / decoder (codec) has a frame update rate of 20 ms or longer. A low-rate voice codec typically requires only a small number of PRB s on a non-anchor carrier 34 to carry a voice data for a user every 20ms, leaving the remaining PRBs of the non-anchor carrier 34 unused. When a non-anchor carrier 34 is not fully loaded (not 100% loaded), the average EIRP in 180 kHz, when measured over a longer time period, will be less than the assigned carrier EIRP. The scheduler in the radio base station 108 takes advantage of its knowledge of channel utilization to increase the power of PRB subframes actively serving the Narrowband Physical Downlink Control Channel (NPDSCH), while maintaining an average EIRP at assigned level. In such instances, the served UTs 14 may benefit from an increased link level performance and thus potentially an increased data rate or link resilience depending on the modulation and coding applied. As the number of voice users sharing a non-anchor carrier 34 increases, the radio base station 108 dynamically adjusts the PRB power of the NPDSCH channel to maintain average EIRP constant.

[0060] Figure 9 illustrates operation without power boosting based on channel utilization, while Figure 10 illustrates operation with power boosting. Both figures illustrate 20 ms intervals for an example case where the communication service being provided via hotspot coverage is voice and involves the transmission of new voice data and / or silence information on a 20 msperiodicity. The number of PRBs needed to carry voice traffic for a given UT 14 in any given transmission depends on vocoder efficiency.

[0061] Notably, modifications and other embodiments of the disclosed invention(s) will come to mind to one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the invention(s) is / are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of this disclosure. Although specific terms may be employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

CLAIMSWhat is claimed is:

1. A method of operation by a Non-Terrestrial Network (NTN) with respect to a multicarrier Narrowband Internet-of-Things (NB-IoT) cell provided by the NTN, the method comprising: providing NB-IoT connectivity for the NB-IoT cell via an anchor carrier that carries synchronization signals and broadcast information for the NB-IoT cell, the anchor carrier associated with an anchor beam that illuminates an overall service area of the NB-IoT cell; and providing, as part of the NB-IoT connectivity, a communication service to individual terminals within the overall service area, using dynamically activated non-anchor carriers and where each non-anchor carrier is associated with a corresponding non-anchor beam that illuminates a respective localized service area within the overall service area; wherein providing the communication service to any given terminal in the overall service area comprises assigning the given terminal to an existing non-anchor carrier provided that there is an existing non-anchor carrier associated with a respective localized service area that contains the given terminal and further provided that that existing non-anchor carrier has remaining service capacity for supporting the given terminal, and otherwise dynamically activating a new non-anchor carrier and a new associated non-anchor beam for serving the given terminal.

2. The method according to claim 1, wherein the communication service is a real-time service.

3. The method according to claim 1 or 2, wherein the communication service is a voice service.

4. The method according to claim 2, wherein the voice service is an Internet Multimedia System (IMS) voice service.

5. The method according to any one of claims 2-4, further comprising initiating the communication service towards any particular terminal operating in the overall service area, based on receiving incoming signaling from an external network requesting initiation of thecommunication service for the particular terminal and, in response, determining non-anchor carrier assignment information for the particular terminal, and using the anchor carrier to configure the particular terminal for operation on an assigned non-anchor carrier.

6. The method according to any one of claims 2-4, further comprising receiving signaling from any particular terminal operating in the overall service area, the signaling received via the anchor carrier and indicating initiation of the communication service by the particular terminal and, in response, determining non-anchor carrier assignment information for the particular terminal, and using the anchor carrier to configure the particular terminal for operation on an assigned non-anchor carrier.

7. The method according to any one of claims 1-6, further comprising performing loadbased power control for each existing non-anchor carrier to maximize a Physical Resource Block (PRB) transmit power while maintaining an average Effective Isotropic Radiated Power (EIRP) below a maximum allowed average EIRP applicable to each existing non-anchor carrier.

8. The method according to any one of claims 1-6, wherein the method includes operating the NTN with respect to the overall service area according to a beamforming solution comprising a plurality of beamforming weights resulting in formation of the anchor beam and each existing non-anchor beam.

9. The method according to claim 8, further comprising, in association with dynamically activating a new non-anchor carrier, updating the beamforming solution to account for the new non-anchor beam associated with the new non-anchor carrier.

10. The method according to claim 8 or 9, further comprising deactivating an existing non- anchor carrier responsive to no terminal illuminated by the corresponding non-anchor beam being active with respect to the communication service, and updating the beamforming solution to account for the deactivation.

11. The method according to claim any one of claims 8-10, further comprising applying the beamforming solution in a ground segment of the NTN configured for ground based beamforming (GBBF).

12. The method according to any one of claims 8-10, further comprising applying the beamforming solution onboard a satellite of the NTN that provides the NB-IoT connectivity for the overall service area.

13. The method according to claim 12, further comprising computing the beamforming solution in a ground segment of the NTN and transmitting the beamforming solution from the ground segment to the satellite, for application onboard the satellite.

14. The method according to any one of claims 1-13, wherein a geosynchronous satellite of the NTN provides the NB-IoT connectivity for the overall service area.

15. A Non-Terrestrial Network (NTN) comprising: a satellite configured to provide Narrowband Internet-of-Things (NB-IoT) connectivity for an NB-IoT cell of the NTN via an anchor carrier that carries synchronization signals and broadcast information for the NB-IoT cell, the anchor carrier associated with an anchor beam that illuminates an overall service area of the NB- loT cell; and communications processing circuitry onboard the satellite or in a ground segment of the NTN, wherein the communications processing circuitry is configured to provide, as part of the NB-IoT connectivity, a communication service to individual terminals within the overall service area, the communication service provided using dynamically activated non-anchor carriers, where each non-anchor carrier is associated with a corresponding non-anchor beam that illuminates a respective localized service area within the overall service area; wherein, with respect to providing the communication service to any given terminal in the overall service area, the communications processing circuitry is configured to assign the given terminal to an existing non-anchor carrier provided that there is an existing non-anchor carrier associated with a respective localized service area that contains the given terminal and further provided that that existing non-anchor carrier has remaining service capacity for supporting the given terminal, and otherwise dynamically activate a new non-anchor carrier and a new associated non-anchor beam for serving the given terminal.

16. The NTN according to claim 15, wherein the communication service is a real-time service.

17. The NTN according to claim 15 or 16, wherein the communication service is a voice service.

18. The NTN according to claim 17, wherein the voice service is an Internet Multimedia System (IMS) voice service.

19. The NTN according to any one of claims 16-18, wherein, with respect to the NTN receiving incoming signaling from an external network requesting initiation of the communication service for the particular terminal operating in the overall service area, the communications processing circuitry is configured to initiate the communication service towards the particular terminal, including determining non-anchor carrier assignment information for the particular terminal and using the anchor carrier to configure the particular terminal for operation on an assigned non-anchor carrier.

20. The NTN according to any one of claims 16-18, wherein, with respect to the NTN receiving signaling via the anchor carrier from any particular terminal operating in the overall service area that indicates initiation of the communication service by the particular terminal, the communications processing circuitry is configured to initiate the communication service for the particular terminal by determining non-anchor carrier assignment information for the particular terminal and using the anchor carrier to configure the particular terminal for operation on an assigned non-anchor carrier.

21. The NTN according to any one of claims 15-20, wherein the communications processing circuitry is configured to perform load-based power control for each existing non-anchor carrier to maximize a Physical Resource Block (PRB) transmit power while maintaining an average Effective Isotropic Radiated Power (EIRP) below a maximum allowed average EIRP applicable to each existing non-anchor carrier.

22. The NTN according to any one of claims 15-21, wherein the NTN includes beamforming circuitry that operates according to a beamforming solution comprising a plurality of beamforming weights resulting in formation of the anchor beam and each existing non-anchor beam.

23. The NTN according to claim 22, wherein, in association with dynamically activating a new non-anchor carrier, a beamforming weight calculation circuit is configured to update the beamforming solution to account for the new non-anchor beam associated with the new nonanchor carrier.

24. The NTN according to claim 22 or 23, wherein the communications processing circuitry is configured to deactivate an existing non-anchor carrier responsive to no terminal illuminated by the corresponding non-anchor beam being active with respect to the communication service and wherein the beamforming weight calculation circuit is configured to update the beamforming solution to account for the deactivation.

25. The NTN according to claim any one of claims 22-24, wherein a ground segment of the NTN is configured for ground based beamforming (GBBF) and includes the beamforming circuitry.

26. The NTN according to any one of claims 22-24, wherein the beamforming circuitry is onboard the satellite and is configured to apply the beamforming solution onboard the satellite.

27. The NTN according to claim 26, wherein the beamforming weight calculation circuit resides in a ground segment of the NTN and is configured to compute the beamforming solution for transmission of the beamforming solution from the ground segment to the satellite.

28. The NTN according to any one of claims 15-27, wherein the satellite is a geosynchronous satellite.

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