Methods and apparatuses for connectionless emergency access in non-terrestrial networks using satellites

Abstract

Disclosed methods and apparatuses provide connectionless emergency access to user terminals (UTs) operating in a satellite-based service area of a non-terrestrial network (NTN). Example advantages include providing for the connectionless emergency access with lightweight or semi- persistent Downlink (DL) signaling used in the satellite-based service area, at least with respect to supporting connectionless emergency accesses. Other advantages include low-latency with respect to transmission of emergency information, and the option of using the same, statically or globally defined resources for the entire service area, even in cases where NTN-based access divides the service area into multiple cells.

Description

METHODS AND APPARATUSES FOR CONNECTIONLESS EMERGENCY ACCESS IN NON-TERRESTRIAL NETWORKS USING SATELLITESTECHNICAL FIELD

[0001] Disclosed methods and apparatuses relate to providing connectionless emergency access to user terminals (UTs) operating in a satellite-based service area of a non-terrestrial network (NTN).BACKGROUND

[0002] Cellular communications systems began as terrestrial networks, but contemporary wireless communications systems may include both terrestrial networks and non-terrestrial networks (NTNs). For example, Release 17 of the specifications maintained by the Third Generation Partnership Project (3GPP) introduced normative requirements for the use of NTNs in the context of 3GPP-based wireless communications systems.

[0003] In an example deployment, a wireless communications system includes one or more NTN-based cells, where “cell” broadly refers to particular radio resources and control information used for access and mobility within a corresponding physical service area. For example, the wireless communications system includes base stations or other radio access points that use antenna systems and defined radiofrequency carriers to provide service in one or more defined service areas, where a “service area” is an area of network coverage. Cells may be static or dynamic, such as where the radio access points use dynamic beam steering.

[0004] Incorporation of NTN-based cells brings with it numerous challenges, arising not least from factors such as longer propagation delays compared to conventional terrestrial radio links, along with the correspondingly larger Doppler shifts and Doppler rate. Other complications include potentially significant variations in path loss of over time. A particular challenge relates to limitations on Downlink (DL) capacity in at least some NTN contexts. DL capacity refers, for example, to the aggregate DL throughput supportable by the network in a cell.

[0005] DL capacity limitations mean, for example, that NTN cells may not transmit all of the various DL channels or signals used for access control and mobility management of user terminals (UTs), or at least not transmit them with the same “density” in the time and / or frequency domains. Consequently, it may be more difficult for conventional UTs to establish a connection with a NTN cell, or, at the least, connection establishment may be a slower or higher- overhead process as compared to connection establishment in a conventional terrestrial-based cell.

[0006] Capacity limitations and other NTN-related issues may raise particular challenges with respect to providing service to UTs operating as Narrowband Internet-of-Things (NB-IoT) devices. For example, an NTN cell or cells may be configured to provide access to a large population of machine-type-communication (MTC) devices, such as one or more kinds of sensors. Various parameters characterize NB-IoT communications, such as the use of narrower frequency channel bandwidths as compared to the channel bandwidths used in Long Term Evolution (LTE) or New Radio (NR), and the use of multiple transmission repetitions for coverage enhancement.SUMMARY

[0007] Disclosed methods and apparatuses provide connectionless emergency access to user terminals (UTs) operating in a satellite-based service area of a non-terrestrial network (NTN). Example advantages include providing for the connectionless emergency access with lightweight or semi-persistent Downlink (DL) signaling used in the satellite-based service area, at least with respect to supporting connectionless emergency accesses. Other advantages include low-latency with respect to transmission of emergency information, and the option of using the same, statically or globally defined resources for the entire service area, even in cases where NTN- based access divides the service area into multiple cells.

[0008] One embodiment comprises a method of operation by a UT that is configured for operation with an NTN and located in a satellite-based service area of the NTN. The method includes the UT detecting an emergency event and initiating a connectionless emergency access to the NTN in response to the detected emergency event. The UT performs the connectionless emergency access by reading provisioned information stored in the UT, to identify a pool of uplink resources designated over the satellite service area for contention-based use by UTs attempting connectionless emergency accesses, and transmitting, on an initial basis, an emergency uplink (UE) burst containing replicated transmissions. Each replica in the emergency UL burst occupies respective uplink resources selected autonomously by the UT from the pool, and each replica carries common information indicating a current location of the UT and carries pointers identifying the respective uplink resources occupied by the other replicas in the emergency UL burst.

[0009] A related embodiment comprises a UT that includes radio transceiver circuitry and communications processing circuitry. The radio transceiver circuitry is configured for communicating with a NTN, with respect to the UT being located in a satellite-based service area of the NTN, and the communications processing circuitry is configured to detect anemergency event and initiate a connectionless emergency access to the NTN in response to the detected emergency event. The communications processing circuitry performs the connectionless emergency access via the radio transceiver circuitry based on reading provisioned information stored in the UT, to identify a pool of uplink resources designated over the satellite-based service area for contention-based use by UTs attempting connectionless emergency accesses. Further, the communications processing circuitry, via the radio transceiver circuitry, transmits, on an initial basis, an emergency UL burst containing replicated transmissions. Each replicated transmission (replica) occupies respective uplink resources that are selected autonomously by the communications processing circuitry from the pool. Each replica in the emergency UL burst carries common information indicating a current location of the UT and carries pointers identifying the respective uplink resources occupied by the other replicas in the burst.

[0010] Another embodiment comprises a method of operation by non-terrestrial network (NTN) that provides wireless access to UTs over a satellite-based service area. The method includes allocating a pool of uplink resources for contention-based use by UTs within the satellite-based service area attempting connectionless emergency accesses. In this context, any given UT attempts a connectionless emergency access by transmitting an emergency UL burst containing replicated transmissions. Each replica occupies respective resources in the pool as selected autonomously by the given UT and carries common information indicating a location of the given UT. Each replica further carries pointers to the respective uplink resources occupied by the other replicas in the emergency UL burst. Correspondingly, the method further includes monitoring the pool of uplink resources for connectionless emergency accesses by the UTs, and responsive to successful detection of an emergency UL burst: transmitting a response to the UT that originated the burst: using the pointers included in the replica(s) within the emergency UL burst that were successfully detected to identify the respective uplink resources occupied by the other replicas in the detected emergency UL burst, and canceling the interference attributable to the other replicas from the identified respective uplink resources. Such cancelation increases the probability of successful detection of colliding emergency UL bursts from one or more other UTs having replicated transmissions on the identified respective uplink resources.

[0011] A related embodiment comprises an NTN that includes a satellite configured to provide wireless coverage for UTs located in a corresponding satellite-based service area and further includes communications processing circuitry onboard the satellite or included in a ground segment. The communications processing circuitry is configured to allocate a pool of uplink resources for contention-based use by the UTs in attempting connectionless emergency accesses, monitor the pool of uplink resources for connectionless emergency accesses by the UTs. Further, the communications processing circuitry is configured to, in response to successfuldetection of emergency UL burst: transmit a response to the UT that originated the successfully detected emergency UL burst, use the pointers included in the successfully detected replica(s) within the burst to identify the respective uplink resources occupied by the other replicas in the burst, and cancel the interference attributable to the other replicas from the identified respective uplink resources. In one or more embodiments, the communications processing circuity performs such interference cancellation in the context of attempting to detect one or more other colliding emergency UL bursts that used the identified respective uplink resources.

[0012] 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

[0013] Figure l is a block diagram of a non-terrestrial network (NTN), according to an example embodiment.

[0014] Figure 2 is a diagram of resource pool allocation in support of connectionless emergency access by user terminals (UTs) to an NTN, according to an example embodiment.

[0015] Figure 3 is a logic flow diagram of a method of operation by a NTN to support connectionless emergency access, according to an example embodiment.

[0016] Figure 4 is a block diagram of implementation details for a satellite and a gateway station of a NTN, according to an example embodiment.

[0017] Figure 5 is a block diagram of implementation details for a UT configured to perform connectionless emergency access to an NTN, according to an example embodiment.

[0018] Figure 6 is a logic flow diagram of a method of operation by a UT for performing connectionless emergency access, according to an example embodiment.DETAILED DESCRIPTION

[0019] Figure 1 illustrates an example Non-Terrestrial Network (NTN) 10 based on the use of a satellite 12 in a space segment of the NTN 10 having a bent-pipe configuration. For transmission of forward user traffic and / or control signaling to user terminals (UTs) 14 located in a satellite-based service area 16 (“service area 16”) of the satellite 12, a ground-based Radio Access Network (RAN) base station 18 generates “normal” cellular downlink (DL) waveforms, such as Orthogonal Frequency Division Multiplexing (OFDM) symbols with user data and control channels. Instead of feeding these cellular DL signals to a terrestrial antenna system, the RAN base station 18 sends them to a terrestrial gateway station 20 in a ground segment of theNTN 10. For example, the RAN base station 18 transmits the cellular DL signals as In- phase / Quadrature (I / Q) samples or radiofrequency (RF) signals.

[0020] The gateway station 20 conveys the cellular DL signals to the satellite 12 via a feeder uplink 24, which may be a RF uplink or an optical uplink. The satellite 12 receives the cellular DL signals on the feeder uplink 24 and retransmits them on a cellular DL 26 provided by its onboard radiofrequency transceivers and associated user-link antenna system. In this bent-pipe example, the satellite 12 does not process or alter the cellular DL signals, although it may frequency-shift them to a desired cellular DL frequency band and may provide amplification and / or beamforming.

[0021] In the return or cellular uplink (UL) direction, UTs 14 transmit cellular UL signals on a cellular UL 28, with the satellite 12 relaying those cellular UL signals to the RAN base station 18, based on transmitting them to the gateway station 20 on a feeder downlink 30. Again, while the satellite 12 may perform signal amplification and frequency shifting on the cellular UL signals received from the UTs 14 on the cellular UL 28, it does not perform demodulation or other processing — hence, the feeder downlink 30 simply conveys the cellular UL signals from the UTs 14, for transfer to the RAN base station 18.

[0022] While not explicitly shown in Figure 1, each satellite 12 in one or more embodiments includes separate transceiver and antenna subsystems for the user link and the feeder link. For example, in at least one embodiment, the feeder link is optical, with the cellular UL and DL signals impressed on optical carriers. The user link is a radiofrequency (RF) link conforming with the cellular standard(s) implemented by the NTN 10 and the RAN base station 18 provides baseband processing for the cellular UL and DL directions, and communicatively couples with a cellular core network 32. The core network 32 provides access to one or more external networks 34, such as the Internet and provides a multiplicity of supporting functions for the UTs 14, such as authentication, mobility management, billing, etc.

[0023] Several points worth emphasizing include the fact that the foregoing bent-pipe context serves as a non-limiting example. In one or more embodiments, the satellite 12 is a “processing” satellite that performs signal demodulation / modulation and provides baseband processing in the digital domain. Such embodiments may integrate the RAN base station 18 into the satellite 12, with the RAN base station 18 communicatively coupling to the cellular core network 32 through the feeder uplink 24 and the feeder downlink 30.

[0024] Other points include the fact that Figure 1 illustrates single entities for simplicity — the NTN 10 may include multiple satellites 12, multiple gateway stations 20, and multiple RAN base stations 18. Each satellite 12 may provide more than one service area 16 and each service area 16 may be operated as one cell of the NTN 10 or may be subdivided into a plurality of cellsof the NTN 10. Further, in one or more implementations, the satellite(s) 12 are geostationary or geosynchronous satellites, while in other implementations they are Medium Earth Orbit (MEO) or Low Earth Orbit (LEO) satellites. As such, the service area(s) 16 may be fixed regions on the surface of the Earth, or may be dynamic, following along the ground track(s) of the satellite(s) 12. In at least one embodiment, one or more satellites 12 are geostationary satellites that provide service coverage over one or more defined satellite-based service areas.

[0025] The air interface — the cellular UL 28 and cellular DL 26 — between a satellite 12 and the UTs 14 supported by it may be understood as a set of resources. In an OFDM context, the resources comprise time-frequency resources. For example, in New Radio (NR) as defined by the Third Generation Partnership Project (3GPP), the physical layer is organized on an OFDM time-frequency grid, where the basic assignable resource is a “resource element” (RE) that comprises one subcarrier in frequency by one OFDM symbol in time.

[0026] Subcarriers are spaced by a configurable subcarrier spacing, and OFDM symbols are grouped into slots (typically 14 symbols for normal cyclic prefix). The number of slots per millisecond depends on the subcarrier spacing. REs are grouped in frequency into resource blocks (RBs), each RB being 12 consecutive subcarriers wide over one slot in time; when scheduled to a UT, these RBs become physical resource blocks (PRBs), which are the granularity of resource allocation for data and control. All NR physical channels, such as the Physical Downlink Shared Channel (PDSCH), the Physical Uplink Shared Channel (PUSCH), and Physical Downlink Control Channel (PDCCH), are mapped onto sets of REs within the time-frequency grid according to standard-defined patterns and UE-specific scheduling.

[0027] Figure 2 illustrates an advantageous allocation by the NTN 10 of a pool 40 of UL resources from an overall pool 42 of resources. Here, “resource” refers to radio resources available for transmitting in the UL or DL. In one or more embodiments, the overall pool 42 comprises Narrowband Internet-of-Things (NB-IoT) resources, as defined by the 3GPP. See, for example, the current versions of 3GPP Technical Specification (TS) 36.300, TS 36.211, TS 36.212, TS 36.213, along with TS 36.331, and TS 24.301. Access to the NTN 10 by a UT in the NB-IoT context conventionally relies on a four-step random access (RA) process preceded by the UT detecting certain downlink signals and broadcast information. In particular, conventional access to an NB-IoT cell includes a UT detecting a Narrowband Primary Synchronization Signal (NPSS) that is transmitted in Subframe 5 of each 10 millisecond NB-IoT radio frame and a Narrowband Secondary Synchronization Signal (NSSS) that is transmitted in Subframe 9 of every even NB-IoT radio frame.

[0028] Such downlink signals provide for synchronization of the UT with the network and cell identification, based upon which the UT acquires System Information (SI). SI includes aNarrowband Master Information Block or MIB-NB, along with a Narrowband System Information Block 1 (SIB1-NB), and a Narrowband System Information Block 2 (SIB2-NB). MIB-NB, as conveyed on a Narrowband Physical Broadcast Channel (NPBCH) indicates cell bandwidth and scheduling information for acquiring additional SI, while SIB1-NB and SIB2-NB provide additional access information.

[0029] Conventionally, a UT must listen on the cellular DL for NPSS / NSSS, acquire MIB- NB, SIB1-NB, and SIB2-NB, and use the acquired information to initiate a four-step random access (RA) procedure, referred to as NPRACH in the NB-IoT context. The procedure includes the UT transmitting a preamble on NPRACH resources, referred to as “Msgl ” The network returns a Random Access Response or RAR, which is referred to as “Msg2.”

[0030] Upon reception of Msg2, the UT proceeds with transmission of “Msg3,” which serves as a Radio Resource Control (“RRC”) connection / resume request and may include “early data.” Early data allows the UT to send a limited amount of data as part of the four-step RA procedure but is still predicated on the initial requirement of the UT detecting the key downlink signals and channels for acquiring synchronization and SI. Upon receiving Msg3, the network responds with “Msg4,” which includes RRC Connection Setup or Resume messaging for contention resolution. Upon completion of the four-step RA procedure, the conventional UT sends a RRC Connection Setup Complete message, which carries an initial Non-Access Stratum (NAS) message, comprising an Attach Request or a Service Request, such as relating to Control Plane (CP) data messaging.

[0031] Contrastingly, the NTN 10 allocates the pool 40 for contention-based use by UTs 14 within the service area 16, for attempting “connectionless emergency accesses.” As defined and described herein, connectionless emergency access is an advantageous SOS procedure. In one or more embodiments, connectionless emergency access comprises a UT 14 selecting random resources from a pool of contention-based UL resources and using the randomly selected UL resources to send an emergency UL burst with repetition / coding. The emergency UL burst may contain registration information for the UT 14, and the NTN 10 may respond to detection of an emergency UL burst. In response to successful detection by the NTN 10 of an emergency UL burst, the NTN 10 may respond with an acknowledgment (ACK), which may include a payload. The ACK may be structured similar to the MSG4 used in the conventional RA procedure.

[0032] Thus, connectionless emergency access as defined herein is its own contention-based uplink procedure and does not rely on establishing connectivity using the conventional four-step RA procedure described above. That is, connectionless emergency access is an initial access procedure not predicated on RA and not predicated on the UT 14 having any UT-specific UL resources allocated to it. Further, in at least some embodiments, connectionless emergencyaccess is independent of concurrent acquisition by the involved UT 14 of the key DL synchronization signals and broadcast channels described above. For example, a UT 14 performing a connectionless emergency access in one or more embodiments advantageously uses stored cell ID(s) and / or Public Land Mobile Network (PLMN) ID(s), and stored synchronization information for the NTN 10 when performing connectionless emergency access. Here, “stored” denotes information provisioned in the UT 14 or otherwise acquired at a prior time rather than based on live reception of the aforementioned DL signals and channels contemporaneously with the connectionless emergency access attempt.

[0033] Thus, connectionless emergency access by any given UT 14 means that the emergency access occurs as an initial UL transmission and without an established radio connection between the given UT 14 and the NTN 10, and independent of conventional RA operations. In the example context of 3GPP specifications, the lack of an established radio connection can be understood as the UT 14 not being in the Radio Resource Control Connected (RRC Connected) state and not otherwise having any granted UL resources.

[0034] In one or more embodiments, the allocation of the pool 40 for contention-based use by UTs 14 attempting connectionless emergency access is not exclusive. For example, the NTN 10 in one or more embodiments uses all or some of the pool 40 for one or more other purposes, such as for scheduled transmissions. The NTN 10 in one or more embodiments uses the pool 40 to support non-emergency communications with UTs 14. In the NB-IoT context, the pool 40 may be contention-based with respect to connectionless emergency access attempts by UTs 14 but also may be used on a scheduled basis by the NTN 10 for providing NB-IoT connectivity and services to the population of UTs 14 in the service area 16.

[0035] The user link (cellular DL 26 / cellular UL 28) may be in NTN Band 255, which is a frequency band defined in New Radio (NR) for NTN. Further, the PLMN ID / cell ID used for connectionless emergency access in the service area 16 may be global, even where the service area 16 is subdivided into multiple cells for managing conventional NB-IoT services. In at least one embodiment, the same PLMN and / or cell IDs are used globally across any number of service areas 16, such that a UT 14 attempting connectionless emergency access uses the same information irrespective of which service area 16 and / or which satellite 12 is involved. Along the same lines, the allocated resource pool 40 may be the same across service areas 16 and / or satellites 12.

[0036] Further, in the case that the example satellite 12 is a geosynchronous satellite, an existing challenge with delivering NB-IoT is the limited DL budget (in terms of available power). Such limitations do not apply to the UL, and it may thus be said that NB-IoT service delivery is downlink-limited in the geo-satellite context, and that problem highlights a furtheradvantage associated with the disclosed arrangement for connectionless emergency access. Namely, a UT 14 attempting connectionless emergency access does not require contemporaneous reception of downlink signals and channels from the NTN 10, which means that the NTN 10 may reduce the density or periodicity of DL beams and / or DL sync signals and broadcast information.

[0037] A UT 14 attempting connectionless emergency access need not be registered with the NTN 10 in advance of the need or attempt for emergency access. For example, in one or more embodiments, the UT 14 includes registration information in the emergency UL burst transmitted to or via the NTN 10. However, the UT 14 may be “credentialed” in the sense that the UT 14 is permitted to access the NTN 10, e.g., based on one or more identifiers of the UT 14 being recorded in subscriber profile information used by the NTN 10. As a further example, the UT 14 may have previously registered with the NTN 10. Broadly, registration and / or credentialing may be performed in advance of and independent from any connectionless emergency access attempt by the UT 14. In at least one embodiment, the UT 14 is preregistered with the NTN 10, and such preregistration may be offline — not performed in dependence on having radio connectivity with the NTN 10.

[0038] In an example embodiment, as a first or initial step of attempting connectionless emergency access, the UT 14 is programmed at setup with eSIM profile, ephemeris data, registration keys, and information indicating the configured pool 40 of resources to be used for contention-based connectionless emergency access. This initial provisioning information in one or more embodiments includes information indicating the PLMN / Cell IDs to be used for connectionless emergency access. Provisioning uses non-NTN connectivity in some embodiments. For example, the UT 14 communicatively couples to a server, such as an Internetbased provisioning server. In other embodiments, the UT 14 may receive such information via an NTN connection or other cellular connection, during a configuration process that occurs in advance of any connectionless emergency access attempt by the UT 14. Configuration may include loading credentials in the UT 14, such that the UT 14 is authorized to use the NTN 10.

[0039] After such provisioning and deployment of the UT 14, the UT 14 initiates a connectionless emergency access — an SOS procedure. According to the connectionless emergency access, the UT 14 randomly selects resources from the (contention-based) pool 40 and transmits an emergency UL burst using the randomly selected resources. The emergency UL burst contains replicated transmissions, more simply referred to as replicas. Each replica occupies respective uplink resources from the (contention-based) pool 40. The multiple replicas or copies increase the likelihood that the NTN 10 successfully receives at least one of the replicas, where one or more transmissions from the UT 14 may be lost with respect to the NTN10 due to the corresponding resources being contention-based with other UTs 14. In at least one embodiment, the replicas contained in the emergency UL burst are transmitted using coverageenhancement repetition and low-rate coding for robustness.

[0040] Each replica in the emergency UL burst carries information indicating that the access is an “emergency” access and may carry registration information. Still further, each replica carries UT location information, and may carry other information, such as an indication of the type of emergency. While including data in the uplink burst has similarities with the early data transmission provided for in Msg3 of the conventional four-step RA procedure, the emergency UL burst is independent of conventional RA and is not proceeded by or dependent on transmission of Msgl and corresponding reception of Msg2 (thus replacing or obviating the need for performing the convention RA process before attempting / requesting emergency access). Nor is the transmission dependent on contemporaneous acquisition by the UT 14 of NTN downlink signaling, such as NPSS / NSSS and NPBCH. Upon successful reception by the NTN 10 of one or more replicas included in an emergency UL burst transmitted by a UT 14, the NTN 10 in one or more embodiments returns an ACK to the UT 14. This return message may include an UL grant to the UT 14, for connection establishment and further data transfer.

[0041] One or more embodiments disclosed herein for implementation of connectionless emergency access leverage NB-IoT with pre-configuration of contention-based UL resources — contention-based capacity enhancement — together with a stable geo channel. This arrangement creates what amounts to a contention-based emergency access channel (CB-EACH) that does not require the presence of supporting downlink transmissions concurrent with the access attempt and allows for any given UT 14 to include data indicating UT location. In at least some embodiments, an emergency UL burst includes data indicating the type or nature of the emergency. Because of the approach described herein, the CB-EACH provides for robust transmission of SOS signaling by UTs 14, even in challenging link conditions, and without prior downlink synchronization and MIB / SIB acquisition. As noted, the UT 14 may be provisioned or otherwise pre-loaded with the information that would otherwise be provided via live acquisition of the MIB / SIB. Release 19 Uplink Capacity Enhancements or Release 16 Preconfigured Uplink Resources (PUR) may be exploited for pre-configuring a pool of contention-based uplink resources for use by UTs 14 in performing connectionless emergency access. As a point of distinction, however, such PUR-like operations do not involve allocation of resources to any particular UT 14 and instead simply provide for recurring (periodic) allocations of UL resources for contention-based use by UTs 14 attempting connectionless emergency access.

[0042] Example applications for connectionless emergency access include SOS / emergency signaling from smartphones, lightweight location reporting, Maritime personal SOS / PLB / EPIRB, High-Gain / VSAT UT initial access and capacity requests.

[0043] Further advantages are attained in cases where the satellite 12 is a geostationary satellite and the UT 14 is not moving rapidly or within a challenging radio propagation environment. For example, in such cases, the UT 14 may use stored synchronization information determined from a prior connection with the NTN 10, for attempting a connectionless emergency access. For example, at some earlier time in advance of attempting a connectionless emergency access, the UT 14 may have received a timing advance (TA) value from the NTN 10 for use by the UT 14 in synchronizing its UL transmission timing. In the geo-satellite context, the TA value may remain valid for much longer than seen in conventional terrestrial networks, meaning that the UT 14 may save the TA value for later use in attempting connectionless emergency accesses. In this regard, the UT 14 in one or more embodiments uses an extended TA validity timer and considers the stored TA value valid for use in attempting connectionless emergency access for the duration of that extended timer. “Extended” refers to a timer duration longer than conventionally used with respect to terrestrial networks.

[0044] Figure 3 illustrates a method 300 of operation by the NTN 10 according to one or more example embodiments. Here, the NTN 10 provides cellular access over a service area 16. In particular, in at least one example embodiment, the NTN 10 provides NB-IoT services to UTs 14 located in the service area 16.

[0045] The method 300 includes allocating (Block 302) a pool 40 of UL resources for contention-based use by UTs 14 within the service area 16 attempting connectionless emergency accesses. Any given UT 14 in this context attempts a connectionless emergency access by transmitting an emergency UL burst comprising replicated uplink transmissions, referred to as replicas. Each replica occupies respective resources in the pool 40 as selected autonomously by the given UT 14. Each replica carries common information indicating a location of the given UT 14, and each replica further carries pointers to the respective uplink resources occupied by the other (remaining) replicas in the plurality. There are at least two replicas in an emergency UL burst, and, in one or more embodiments, there are at least four.

[0046] The method 300 further includes the NTN 10 monitoring (Block 304) the pool 40 of UL resources for connectionless emergency accesses by the UTs 14. This monitoring can be understood as the NTN 10 listening on a continuing or ongoing basis for connectionless emergency access attempts by any one or more UTs 14 among an overall population of UTs 14 located in the service area 16.

[0047] Successful detection of an emergency UL burst by the NTN 10 refers to successful reception of one or more of the replicas comprised in the emergency UL burst. For example, the NTN 10 successfully detects one or more of the replicas in a given emergency UL burst, but not on the other (remaining) replicas in the emergency UL burst. Responsive to successful detection, the method 300 further includes the NTN 10: transmitting (Block 306) a response to the UT 14 that originated the successfully detected emergency UL burst; using (Block 308) the pointers included in the successfully detected replica(s) to identify the respective uplink resources occupied by the other replica(s) in the emergency UL burst; and canceling (Block 310) the interference attributable to the associated other replicas from the identified respective uplink resources. The NTN 10 uses such interference cancellation for increased probability of successful detection of colliding emergency UL bursts (e.g., from one or more other UTs 14) that use the same resources.

[0048] In particular, connectionless emergency accesses by two or more UTs 14 may collide in the sense that the respective emergency UL bursts use the same resources. For example, one or more of the replicas included in one emergency UL burst by a first UT 14 use the same resources used in another UL emergency burst by a second UT 14. Assuming, for example, that a given one of the replicas included in the emergency UL burst by the first UT 14 is not interfered with by any of the replicas in the emergency UL burst by the second UT 14, the NTN 10 successfully decodes that given replica and uses the decoded replica to obtain pointers to the resources occupied by the other (remaining) replicas in the same emergency UL burst, and it suppresses interference attributable to those other replicas and thus increases the probability of also successfully decoding at least one of the replicas included in the emergency UL burst transmitted by the second UT 14.

[0049] In at least one embodiment, any given UT 14 attempts a connectionless emergency access in accordance with the approach taken in Contention Resolution Diversity Slotted ALOHA (CRD SA). CSRDA is an advanced version of traditional Slotted ALOHA, where a device sends multiple replicas of data packets during different time slots. This approach improves communication efficiency and reliability by allowing the receiver — here, the NTN 10 — to use Successive Interference Cancellation (SIC) to resolve packet collisions, making it particularly useful in environments like loT, where there may be many devices all contending for resources and where network conditions can vary significantly.

[0050] In one or more embodiments, the method 300 further includes the NTN 10 periodically transmitting SI that indicates at least one of: the pool 40 of UL resources, a PLMN ID and / or cell ID to be included in an emergency UL burst from any given UT 14 attempting connectionless emergency access. In at least one such embodiment, the satellite 12 providingcoverage to the service area 16 transmits NPSS / NSSS, along with the SI, with the SI or further assistance information indicating ephemeris data for the satellite 12. In some embodiments, where the NTN 10 periodically transmits SI to UTs 14, the NTN 10 may transmit SI for neighboring pools to UTs 14 (e.g., that are close to a boundary of the pool 40) so that such UTs 14 are ensured to have access to appropriate SI to effectuate emergency access should such UTs 14 move or be relocated to a different location served by a different pool.

[0051] In at least one embodiment the method 300, the method includes operating the pool 40 of UL resources as a pool of NB-IoT resources and scheduling NB-IoT transmissions using resources in the pool 40, in conjunction with monitoring the pool 40 for connectionless emergency uplink accesses.

[0052] The NTN 10 in one or more embodiments is configured to push out updates to the UTs 14, with respect to updating or changing the pool 40, or provide information about different pools 40 relating to different services areas or cells. For example, when a UT 14 is in a location served by or proximate to multiple pools 40, the NTN 10 may provide such information to the UT 14 enabling the UT 14 to attempt connectionless emergency access with the NTN 10 in / via the multiple pools 40. In at least one embodiment, the NTN 10 is configured to determine that a regional or other emergency likely affecting multiple users / UTs 14 is occurring and allocate more resources for connectionless emergency access, or it may stop using already-allocated resources for any other purpose — e.g., the NTN 10 stops using the pool 40 for any scheduled transmissions to maximize resources availability for UTs 14 attempting connectionless emergency access. In at least one embodiment, the NTN 10 determines that a regional or other generally applicable emergency is occurring based on the rate or number of connectionless emergency accesses.

[0053] Figure 4 provides example details for the NTN 10, illustrating a satellite 12 according to one or more embodiments. In at least one such embodiment, the satellite 12 is a geosynchronous satellite and the service area 16 it provides comprises a large geographic region, such as CONUS. Further, although not a limiting aspect, the satellite 12 in the depicted implementation is a bent-pipe satellite.

[0054] As such, the satellite 12 in example bent-pipe form includes a feeder-link antenna or optical subsystem 50 which is configured for transmitting and receiving on the feeder link between it and a supporting gateway station 20. In embodiments where the feeder link is optical, the feeder-link antenna or optical subsystem 50 comprises one or more optical transceivers and the feeder link may use Wavelength Division Multiplexing (WDM) in the optical domain to carry different cellular signals on different optical channels.

[0055] The satellite 12 further includes a plurality of transponders 52, which may include forward-link transponders (towards the UTs 14) and return-link transponders (from the UTs 14), or bidirectional transponders that provide both forward and return link signal paths. While the transponders 52 do not perform signal processing (no demodulation / decoding and no re- encoding / remodulation), they may include filters, frequency converters, amplifiers, or other analog-domain circuitry that does not interfere with or alter the cellular waveforms being transmitted from and received with a user-link antenna subsystem 54. The user-link antenna subsystem 54 may be a multi-feed reflector-based antenna system and may provide or otherwise support one or more beams (spatially directed signal transmission or reception).

[0056] The example gateway station 20 included in the NTN 10 includes a feeder-link antenna or optical subsystem 60, which is configured for feeder-link communications with the satellite 12. Communications processing circuitry 62 included in the gateway station 20 is configured to allocate a pool 40 of UL resources for contention-based use by the UTs 14 in attempting connectionless emergency accesses. As before, any given UT 14 attempts a connectionless emergency access by transmitting an emergency UL burst comprising a plurality of replicated transmissions referred to as replicas; each replica occupies respective resources in the pool 40, as selected autonomously by the given UT 14, and each replica carries common information indicating a location of the given UT 14 and carries pointers to the respective uplink resources occupied by the other replicas in the emergency UL burst.

[0057] The communications processing circuitry 62 is further configured to monitor the pool 40 of uplink resources for connectionless emergency accesses by the UTs 14 and perform one or more operations in response to successful detection of an emergency UL burst. Successful detection refers to successful reception of one or more replicas comprised in the emergency UL burst.

[0058] The communications processing circuitry 62 is configured in one or more embodiments to respond to successful reception of an emergency UL burst by transmitting a response to the UT 14 that originated it, and using the pointers included in the replica(s) within the emergency UL burst that was / were successfully received, to identify the respective uplink resources occupied by the other (remaining) replicas in the emergency UL burst. Based on such identification, the communications processing circuitry 62 cancels the interference attributable to such other replicas from the identified respective uplink resources. The cancelation increases the probability of successful detection by the communications processing circuitry 62 of any emergency UL bursts transmitted on the same resources by one or more other UTs 14.

[0059] The communications processing circuitry 62 comprises, for example, one or more digital-domain processors, such as Digital Signal Processors (DSPs) or Field Programmable GateArrays (FPGAs), along with buffers, data and program memory, and interfaces for sending / receiving signaling via the feeder-link antenna or optical subsystem 60 and a RAN base station interface 64.

[0060] In one or more embodiments, the communications processing circuitry 62 is configured to transmit SI via the satellite 12 periodically, wherein the SI indicates at least one of: the pool 40 of UL resources, a PLMN ID and / or cell ID to be included in emergency UL bursts. Further, the SI in one or more embodiments provides ephemeris data of the satellite 12.

[0061] In at least one embodiment, the communications processing circuitry 62 is configured to operate the pool 40 of UL resources as a pool of NB-IoT resources. In at least one such embodiment, the communications processing circuitry 62 also schedules NB-IoT transmissions using resources in the pool 40, in conjunction with monitoring the pool for emergency uplink accesses. Alternatively, the pool 40 is reserved for connectionless emergency access and the NTN 10 uses other resources for user scheduling.

[0062] Figure 5 illustrates a UT 14 according to an example embodiment, where the UT 14 includes radio transceiver circuitry 70 that is configured for communicating with an NTN 10, with respect to the UT 14 being located in a service area 16 of the NTN 10. The UT 14 further includes communications processing circuitry 72 that is operatively associated with the radio transceiver circuitry 70 and configured to carry out various operations.

[0063] In at least one embodiment, the communications processing circuitry 72 is configured to detect an emergency event. The detection may be direct or indirect. For example, in one embodiment, the UT 14 includes host processing circuitry 74 that executes software applications that provide one or more desired device functions or capabilities, and the host processing circuitry 74 sends signaling to the communications processing circuitry 72 indicating the detection. Depending on its intended functionality, the UT 14 includes interface circuitry 76, which may include or communicatively couple to one or more types of sensors, such as accelerometers, smoke detectors, cameras, thermal sensors, etc. In at least one embodiment, one or more such sensors provide for emergency-event detection. The sensor(s) may provide signaling directly to the communications processing circuitry 72 or it may be provided through the host processing circuitry 74.

[0064] In at least one embodiment, the interface circuitry 76 includes one or more user interface elements, such as a touchscreen, microphone, camera, and / or physical buttons. In such embodiments, one mechanism for detecting an emergency event is receiving user input, indicating occurrence of the emergency event. User input also may be received indicating additional emergency information, such as the type of emergency. Further, the UT 14 in one or more embodiments includes a Global Navigation Satellite System (GNSS) receiver 78, fordetermining the location of the UT 14. The location information included in an emergency UL burst may be GNSS-based location information.

[0065] The communications processing circuitry 72 is configured to initiate a connectionless emergency access to the NTN 10 in response to the detected emergency event and perform the connectionless emergency access via the radio transceiver circuitry 70. Such performance is, based on the communications processing circuitry 72 reading provisioned information stored in the UT 14, to identify a pool 40 of UL resources designated over the service area 16 for contention-based use by UTs 14 attempting connectionless emergency accesses. Further in performing the connectionless emergency access, the communications processing circuitry 72 is configured to transmit, on an initial basis, an emergency UL burst comprising two or more replicated transmissions, referred to as “replicas.” “Initial basis” in this context emphasizes transmission of the emergency UL burst without benefit of a preestablished radio connection or even performing RA, and without need for contemporaneous reception of downlink signaling from the NTN 10.

[0066] In at least one embodiment, the communications processing circuitry 72 is configured to communicate with an Internet-based provisioning server 80, via the radio transceiver circuitry 70 or via another communication interface that is operatively associated with the communications processing circuitry 72 and included in the UT 14, for receiving the provisioned information independent of NTN connectivity. In one example, the interface circuitry 76 includes a Wi-Fi transceiver or other communications interface and the communications processing circuitry 72 uses that interface directly or indirectly via the host processing circuitry 74, to obtain the provisioning information from the provisioning server 80.

[0067] With respect to transmitting an emergency UL burst in any given connectionless emergency access attempt, the communications processing circuitry 72 in one or more embodiments is configured to use a stored TA value for synchronizing an uplink transmission timing of the UT 14 with the NTN 10. In this regard, the communications processing circuitry 72 will be understood as including one or more types of computer readable media, such as volatile and non-volatile memory for working data, program storage, and configuration-data storage.

[0068] In at least one embodiment, the communications processing circuitry 72 is configured to obtain the stored TA value based on prior connectivity with the NTN 10 via the radio transceiver circuitry 70. For example, the stored TA value is based on a most recent prior connectivity with the NTN 10, and the communications processing circuitry 72 is configured to control the UT 14 to connect with the NTN 10 to refresh the stored TA value in response to the most recent prior connectivity with the NTN 10 being older than a defined age threshold.

[0069] In at least one embodiment, the communications processing circuitry 72 is configured to receive a response from the NTN 10 via the radio transceiver circuitry 70, indicating successful reception by the NTN 10 of a least one replica among the plurality of replicas included in an emergency UL burst transmitted by the UT 14. Correspondingly, the communications processing circuitry 72 is configured to control the UT 14 according to the response, to establish a connection with the NTN 10. For example, the response provides RRC connection setup information and an initial UL grant to the UT 14.

[0070] With respect to any given connectionless emergency access attempt, the communications processing circuitry 72 in one or more embodiments is configured to control the UT 14 to repeatedly attempt connectionless emergency access until a corresponding response is received from the NTN 10 or until reaching a defined repetition limit. The defined reception limit may be expiration of a timer that defines a window within which the UT 14 attempts connectionless emergency access, or it may be count value that defines the maximum number of attempts, at least within a given time frame.

[0071] Figure 6 illustrates an example method 600 of operation by a UT 14, with the method 600 including the UT 14 detecting (Block 602) an emergency event. As one example, the UT 14 includes one or more sensors, and it detects the emergency event based on signaling from the one or more sensors. In another example, the UT 14 receives user input from a user of the UT 14, indicating the emergency event. In yet another example, the UT 14 is co-located with or otherwise communicatively associated with another device or system that indicates detection of the emergency.

[0072] The method 600 further includes the UT 14 initiating (Block 604) a connectionless emergency access attempt toward the NTN 10 in response to the detected emergency event, and performing the connectionless emergency access by: reading (Block 606) provisioned information stored in the UT 14, to identify a pool 40 of UL resources designated over a service area 16 for contention-based use by UTs 14 attempting connectionless emergency accesses. The UT 14 performing the connectionless emergency access attempt further includes the UT 14 transmitting (Block 608), on an initial basis, an emergency UL burst comprising a plurality replicated transmissions (replicas). Each replica occupies respective uplink resources selected autonomously by the UT 14 from the pool 40, and each replica carries common information indicating a current location of the UT 14 and carries pointers identifying the respective uplink resources occupied by the other replicas. In at least one embodiment, the replicas carry encoded event information, such as a bit map or a binary-number encoding of emergency information, indicating the type of emergency, etc.

[0073] 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

CLAIMS1. A method of operation by a user terminal (UT) configured for operation with a nonterrestrial network (NTN) and located in a satellite-based service area of the NTN, the method comprising: detecting an emergency event; initiating a connectionless emergency access to the NTN in response to the detected emergency event, and performing the connectionless emergency access by: reading provisioned information stored in the UT, to identify a pool of uplink (UL) resources designated over the service area for contention-based use by UTs attempting connectionless emergency accesses; and transmitting, on an initial basis, an emergency UL burst comprising a plurality of replicated transmissions referred to as replicas, each replica occupying respective uplink resources selected autonomously by the UT from the pool, and each replica carrying common information indicating a current location of the UT and carrying pointers identifying the respective uplink resources occupied by the other replicas.

2. The method according to claim 1, wherein detecting the emergency event comprises at least one of detecting the emergency event based on one or more sensor signals or detecting the emergency event based on user input.

3. The method according to claim 1 or 2, further comprising receiving the provisioned information independent of NTN connectivity.

4. The method according to claim 3, wherein receiving the provisioned information independent of NTN connectivity comprises receiving the provisioned information in a provisioning-based process carried out with an Internet-based provisioning server.

5. The method according to any one of claims 1-4, further comprising, with respect to transmitting the emergency UL burst, using a stored timing advance (TA) value for synchronizing an uplink transmission timing of the UT with the NTN.

6. The method according to claim 5, further comprising obtaining the stored TA value based on prior connectivity with the NTN.

7. The method according to claim 6, wherein the stored TA value is based on a most recent prior connectivity with the NTN, and wherein the method includes connecting with the NTN to refresh the stored TA value responsive to the most recent prior connectivity with the NTN being older than a defined age threshold.

8. The method according to any one of claims 1-7, wherein each replica in the emergency UL burst includes a public land mobile network (PLMN) identifier (ID) of the NTN and a cell ID of the NTN.

9. The method according to claim 8, further comprising obtaining at least one of the PLMN ID and the cell ID from the provisioned information.

10. The method according to claim 8, further comprising obtaining at least one of the PLMN ID and the cell ID from system information (SI) received from the NTN during a prior connection with the NTN.

11. The method according to any one of claims 1-10, wherein the respective uplink resources occupied by the replicas contained in the emergency UL burst are respective time-frequency resources in a time-frequency grid used by the NTN.

12. The method according to any one of claims 1-11, wherein the pool comprises a plurality of UL resources configured for use by Narrowband Internet-of-Things (NB-IoT) devices.

13. The method according to any one of claims 1-12, wherein each replica in the emergency UL burst is a Narrowband Internet-of-Things (NB-IoT) early data transmission.

14. The method according to any one of claims 1-13, wherein each replica in the emergency UL burst carries type information, indicating a type of emergency for which the connectionless emergency access was initiated.

15. The method according to any one of claims 1-14, further comprising receiving a response from the NTN, indicating successful reception by the NTN of the emergency UL burst, and establishing a connection with the NTN based on the response.

16. The method according to any one of claims 1-15, further comprising repeatedly performing the connectionless emergency access until a corresponding response is received from the NTN or until reaching a defined repetition limit.

17. A method of operation by a non-terrestrial network (NTN) that provides cellular access over a satellite-based service area, the method comprising: allocating a pool of uplink (UL) resources for contention-based use by user terminals (UTs) within the satellite-based service area attempting connectionless emergency accesses, and wherein any given UT attempts a connectionless emergency access by transmitting an emergency UL burst comprising a plurality of replicated transmissions referred to as replicas, each replica occupying respective resources in the pool as selected autonomously by the given UT and carrying common information indicating a location of the given UT and carrying pointers to the respective uplink resources occupied by the other replicas; monitoring the pool of uplink resources for connectionless emergency accesses by the UTs; and responsive to successful detection of one or more replicas contained in an emergency UL burst: transmitting a response to the UT that originated the emergency UL burst; using the pointers obtained from one or more successfully detected replicas to identify the respective uplink resources occupied by the other replicas; and canceling the interference attributable to the replicas contained in the emergency UL burst from the identified respective uplink resources, for increased probability of successful detection of emergency UL bursts from one or more other UTs on the identified respective uplink resources.

18. The method according to claim 17, further comprising periodically transmitting System Information (SI) that indicates at least one of: the pool of uplink resources, a Public Land Mobile Network (PLMN) identifier (ID) to be included in emergency UL bursts, or a cell ID to be included in emergency UL bursts.

19. The method according to claim 17 or 18, further comprising operating the pool of uplink resources as a pool of Narrowband Internet-of-Things (NB-IoT) resources and scheduling NB- loT transmissions using resources in the pool, in conjunction with monitoring the pool for emergency uplink accesses.

20. A user terminal (UT) comprising: radio transceiver circuitry configured for communicating with a non-terrestrial network (NTN), with respect to the UT being located in a satellite-based service area of the NTN; and communications processing circuitry operatively associated with the radio transceiver circuitry and configured to: detect an emergency event; initiate a connectionless emergency access to the NTN in response to the detected emergency event, and perform the connectionless emergency access via the radio transceiver circuitry, based on: reading provisioned information stored in the UT, to identify a pool of uplink (UL) resources designated over the satellite-based service area for contention-based use by UTs attempting connectionless emergency accesses; and transmitting, on an initial basis, an emergency UL burst comprising a plurality of replicated transmissions referred to as replicas, each replica occupying respective uplink resources selected autonomously by the communications processing circuitry from the pool, and each replica carrying common information indicating a current location of the UT and carrying pointers identifying the respective uplink resources occupied by the other replicas.

21. The UT according to claim 20, wherein the communications processing circuitry is configured to detect the emergency event via a sensor signal provided by a sensor included in or associated with the UT.

22. The UT according to claim 20, wherein the communications processing circuitry is configured to detect the emergency event via user input provided via a user interface included in or associated with the UT.

23. The UT according to any one of claims 20-22, wherein the communications processing circuitry is configured to communicate with an Internet-based provisioning server via the radio transceiver circuitry or via another communication interface that is operatively associated with the communications processing circuitry and included in the UT, for receiving the provisioned information independent of NTN connectivity.

24. The UT according to any one of claims 20-23, wherein, with respect to the emergency UL burst, the communications processing circuitry is configured to use a stored timing advance (TA) value for synchronizing an uplink transmission timing of the UT with the NTN.

25. The UT according to claim 24, wherein the communications processing circuitry is configured to obtain the stored TA value based on prior connectivity with the NTN via the radio transceiver circuitry.

26. The UT according to claim 25, wherein the stored TA value is based on a most recent prior connectivity with the NTN, and wherein the communications processing circuitry is configured to control the UT to connect with the NTN to refresh the stored TA value in response to the most recent prior connectivity with the NTN being older than a defined age threshold.

27. The UT according to any one of claims 20-26, wherein each replica in the emergency UL burst commonly includes a public land mobile network (PLMN) identifier (ID) of the NTN and a cell ID of the NTN.

28. The UT according to claim 27, wherein the communications processing circuitry is configured to obtain at least one of the PLMN ID and the cell ID from the provisioned information.

29. The UT according to claim 27, wherein the communications processing circuitry is configured to obtain at least one of the PLMN ID and the cell ID from system information (SI) received from the NTN during a prior connection of the UT with the NTN.

30. The UT according to any one of claims 20-29, wherein the respective uplink resources occupied by the plurality of replicas in the emergency UL burst are respective time-frequency resources in a time-frequency grid used by the NTN.

31. The UT according to any one of claims 20-30, wherein the pool comprises a plurality of uplink resources configured for use by Narrowband Internet-of-Things (NB-IoT) devices.

32. The UT according to any one of claims 20-31, wherein each replica in the emergency UL transmission is a Narrowband Internet-of-Things (NB-IoT) early data transmission.

33. The UT according to any one of claims 20-32, wherein each replica in the emergency UL burst commonly carries type information, indicating a type of emergency for which the connectionless emergency access was initiated.

34. The UT according to any one of claims 20-33, wherein the communications processing circuitry is configured to receive a response from the NTN via the radio transceiver circuitry, indicating successful reception by the NTN of the emergency UL burst, and correspondingly control the UT to establish a connection with the NTN, based on the response.

35. The UT according to any one of claims 20-34, wherein the communications processing circuitry is configured to control the UT to repeatedly attempt connectionless emergency accesses until a corresponding response is received from the NTN or until reaching a defined repetition limit.

36. A non-terrestrial network (NTN) comprising: a satellite configured to provide non-terrestrial network (NTN) coverage for user terminals (UTs) located in a corresponding satellite-based service area; and communications processing circuitry onboard the satellite or included in a ground network of the NTN, the communications processing circuitry configured to: allocate a pool of uplink (UL) resources for contention-based use by the UTs in attempting connectionless emergency accesses, wherein any given UT attempts a connectionless emergency access by transmitting an emergency UL burst comprising a plurality of replicated UL transmissions referred to as replicas, each replica occupying respective resources in the pool as selected autonomously by the given UT and carrying common information indicating a location of the given UT, and each replica further carrying pointers to the respective uplink resources occupied by the other replicas; monitor the pool of uplink resources for connectionless emergency accesses by the UTs; and in response to successful detection of an emergency UL burst: transmit a response to the UT that originated the emergency UL burst; use the pointers included in a successfully decoded one or ones among the plurality of replicas contained in the emergency UL burst to identify the respective uplink resources occupied by the other replicas in the emergency UL burst; and cancel the interference attributable to the other replicas from theidentified respective uplink resources, for increased probability of successful detection of any emergency UL bursts transmitted by one or more other UTs on the identified respective uplink resources.

37. The NTN according to claim 36, wherein the communications processing circuitry is configured to transmit System Information (SI) via the satellite periodically, wherein the SI indicates at least one of: the pool of uplink resources, a Public Land Mobile Network (PLMN) identifier (ID) to be included in emergency UL bursts, or a cell ID to be included in emergency UL bursts.

38. The NTN according to claim 36 or 37, wherein the communications processing circuitry is configured to operate the pool of uplink resources as a pool of Narrowband Internet-of-Things (NB-IoT) resources and schedule NB-IoT transmissions using resources in the pool, in conjunction with monitoring the pool for emergency uplink accesses.

Images