WO2022043608A1

WO2022043608A1 - Interference estimation for improved reliability of connectivity

Info

Publication number: WO2022043608A1
Application number: PCT/FI2021/050569
Authority: WO
Inventors: István Zsolt KOVÁCS; Ryan Keating; Jeroen Wigard
Original assignee: Nokia Technologies Oy
Priority date: 2020-08-25
Filing date: 2021-08-24
Publication date: 2022-03-03

Abstract

Disclosed is a method comprising estimating an interference range and an interference change rate associated with one or more signals received from a satellite, wherein the interference range and the interference change rate are based on a plurality of estimated interference values that are estimated periodically at a pre-defined time interval. The time interval is then adjusted based at least partly on the estimated interference range and the interference change rate.

Description

INTERFERENCE ESTIMATION FOR IMPROVED RELIABILITY OF CONNECTIVITY

FIELD

The following exemplary embodiments relate to wireless communication and to non-terrestrial networks.

BACKGROUND

As resources are limited, it is desirable to optimize the usage of resources in a non-terrestrial network. A terminal device may be utilized to enable better usage of resources and enhanced user experience to a user of the terminal device.

SUMMARY

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

According to an aspect, there is provided an apparatus comprising at least one processor, and at least one memory including computer program code, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to: estimate an interference range and an interference change rate associated with one or more signals received from a satellite, wherein the interference range and the interference change rate are based on a plurality of estimated interference values that are estimated periodically at a pre-defined time interval, and to adjust the time interval based at least partly on the estimated interference range and the interference change rate.

According to another aspect, there is provided an apparatus comprising means for estimating an interference range and an interference change rate associated with one or more signals received from a satellite, wherein the interference range and the interference change rate are based on a plurality of estimated interference values that are estimated periodically at a pre-defined time interval, and means for adjusting the time interval based at least partly on the estimated interference range and the interference change rate.

According to another aspect, there is provided a system comprising at least a terminal device and a satellite, wherein the satellite is configured to transmit one or more signals to the terminal device, and wherein the terminal device is configured to: receive the one or more signals from the satellite, estimate an interference range and an interference change rate associated with the one or more signals received from the satellite, wherein the interference range and the interference change rate are based on a plurality of estimated interference values that are estimated periodically at a pre-defined time interval, and to adjust the time interval based at least partly on the estimated interference range and the interference change rate.

According to another aspect, there is provided a system comprising at least a terminal device and a satellite, wherein the satellite comprises means for transmitting one or more signals to the terminal device, and wherein the terminal device comprises means for: receiving the one or more signals from the satellite, estimating an interference range and an interference change rate associated with the one or more signals received from the satellite, wherein the interference range and the interference change rate are based on a plurality of estimated interference values that are estimated periodically at a pre-defined time interval, and adjusting the time interval based at least partly on the estimated interference range and the interference change rate.

According to another aspect, there is provided a method comprising estimating an interference range and an interference change rate associated with one or more signals received from a satellite, wherein the interference range and the interference change rate are based on a plurality of estimated interference values that are estimated periodically at a pre-defined time interval, and adjusting the time interval based at least partly on the estimated interference range and the interference change rate.

According to another aspect, there is provided a computer program comprising instructions for causing an apparatus to perform at least the following: estimate an interference range and an interference change rate associated with one or more signals received from a satellite, wherein the interference range and the interference change rate are based on a plurality of estimated interference values that are estimated periodically at a pre-defined time interval, and adjust the time interval based at least partly on the estimated interference range and the interference change rate.

According to another aspect, there is provided a computer readable medium comprising program instructions for causing an apparatus to perform at least the following: estimate an interference range and an interference change rate associated with one or more signals received from a satellite, wherein the interference range and the interference change rate are based on a plurality of estimated interference values that are estimated periodically at a pre-defined time interval, and adjust the time interval based at least partly on the estimated interference range and the interference change rate.

According to another aspect, there is provided a non-transitory computer readable medium comprising program instructions for causing an apparatus to perform at least the following: estimate an interference range and an interference change rate associated with one or more signals received from a satellite, wherein the interference range and the interference change rate are based on a plurality of estimated interference values that are estimated periodically at a pre-defined time interval, and adjust the time interval based at least partly on the estimated interference range and the interference change rate.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, various exemplary embodiments will be described in greater detail with reference to the accompanying drawings, in which

FIG. 1 illustrates an exemplary embodiment of a cellular communication network;

FIG. 2 illustrates an exemplary embodiment of a non-terrestrial network;

FIG. 3 illustrates an exemplary embodiment of a non-terrestrial network with Earth-fixed cells;

FIG. 4 illustrates interference conditions in a non-terrestrial network with Earth-fixed cells;

FIGS. 5-8 illustrate flow charts according to exemplary embodiments;

FIGS. 9a and 9b illustrate simulated measurement results according to exemplary embodiments;

FIGS. 10 and 11 illustrate apparatuses according to exemplary embodiments.

DETAILED DESCRIPTION

The following embodiments are exemplifying. Although the specification may refer to "an", "one", or "some" embodiment's] in several locations of the text, this does not necessarily mean that each reference is made to the same embodiment's], or that a particular feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments. In the following, different exemplary embodiments will be described using, as an example of an access architecture to which the exemplary embodiments may be applied, a radio access architecture based on long term evolution advanced (LTE Advanced, LTE-A) or new radio (NR, 5G), without restricting the exemplary embodiments to such an architecture, however. It is obvious for a person skilled in the art that the exemplary embodiments may also be applied to other kinds of communications networks having suitable means by adjusting parameters and procedures appropriately. Some examples of other options for suitable systems may be the universal mobile telecommunications system (UMTS) radio access network (UTRAN or E-UTRAN), long term evolution (LTE, the same as E-UTRA), wireless local area network (WLAN or Wi-Fi), worldwide interoperability for microwave access (WiMAX), Bluetooth®, personal communications services (PCS), ZigBee®, wideband code division multiple access (WCDMA), systems using ultra-wideband (UWB) technology, sensor networks, mobile ad- hoc networks (MANETs) and Internet Protocol multimedia subsystems (IMS) or any combination thereof.

FIG. 1 depicts examples of simplified system architectures only showing some elements and functional entities, all being logical units, whose implementation may differ from what is shown. The connections shown in FIG. 1 are logical connections; the actual physical connections may be different. It is apparent to a person skilled in the art that the system may also comprise other functions and structures than those shown in FIG. 1.

The exemplary embodiments are not, however, restricted to the system given as an example but a person skilled in the art may apply the solution to other communication systems provided with necessary properties.

The example of FIG. 1 shows a part of an exemplifying radio access network.

FIG. 1 shows user devices 100 and 102 configured to be in a wireless connection on one or more communication channels in a cell with an access node (such as (e/g)NodeB) 104 providing the cell. The physical link from a user device to a (e/g)NodeB may be called uplink or reverse link and the physical link from the (e/g)NodeB to the user device may be called downlink or forward link. It should be appreciated that (e/g)NodeBs or their functionalities may be implemented by using any node, host, server or access point etc. entity suitable for such a usage.

A communication system may comprise more than one (e/g)NodeB, in which case the (e/g)NodeBs may also be configured to communicate with one another over links, wired or wireless, designed for the purpose. These links may be used for signaling purposes. The (e/g)NodeB may be a computing device configured to control the radio resources of communication system it is coupled to. The NodeB may also be referred to as a base station, an access point or any other type of interfacing device including a relay station capable of operating in a wireless environment. The (e/g) NodeB may include or be coupled to transceivers. From the transceivers of the (e/g) NodeB, a connection maybe provided to an antenna unit that establishes bi-directional radio links to user devices. The antenna unit may comprise a plurality of antennas or antenna elements. The (e/g)NodeB may further be connected to core network 110 (CN or next generation core NGC). Depending on the system, the counterpart on the CN side may be a serving gateway (S- GW, routing and forwarding user data packets), packet data network gateway (P-GW), for providing connectivity of user devices (UEs) to external packet data networks, or mobile management entity (MME), etc.

The user device (also called UE, user equipment, user terminal, terminal device, etc.) illustrates one type of an apparatus to which resources on the air interface may be allocated and assigned, and thus any feature described herein with a user device may be implemented with a corresponding apparatus, such as a relay node. An example of such a relay node may be a layer 3 relay (self-backhauling relay) towards the base station.

The user device may refer to a portable computing device that includes wireless mobile communication devices operating with or without a subscriber identification module (SIM), including, but not limited to, the following types of devices: a mobile station (mobile phone), smartphone, personal digital assistant (PDA), handset, device using a wireless modem (alarm or measurement device, etc.), laptop and/or touch screen computer, tablet, game console, notebook, and multimedia device. It should be appreciated that a user device may also be a nearly exclusive uplink only device, of which an example may be a camera or video camera loading images or video clips to a network. A user device may also be a device having capability to operate in Internet of Things (loT) network which is a scenario in which objects may be provided with the ability to transfer data over a network without requiring human-to-human or human-to-computer interaction. The user device may also utilize cloud. In some applications, a user device may comprise a small portable device with radio parts (such as a watch, earphones or eyeglasses) and the computation may be carried out in the cloud. The user device (or in some exemplary embodiments a layer 3 relay node) may be configured to perform one or more of user equipment functionalities. The user device may also be called a subscriber unit, mobile station, remote terminal, access terminal, user terminal, terminal device, or user equipment (UE) just to mention but a few names or apparatuses.

Various techniques described herein may also be applied to a cyber-physical system (CPS) (a system of collaborating computational elements controlling physical entities). CPS may enable the implementation and exploitation of massive amounts of interconnected ICT devices (sensors, actuators, processors microcontrollers, etc.) embedded in physical objects at different locations. Mobile cyber physical systems, in which the physical system in question may have inherent mobility, are a subcategory of cyber-physical systems. Examples of mobile physical systems include mobile robotics and electronics transported by humans or animals.

Additionally, although the apparatuses have been depicted as single entities, different units, processors and/or memory units (not all shown in FIG. 1) may be implemented.

5G may enable using multiple input - multiple output (M1M0) antennas, many more base stations or nodes than the LTE (a so-called small cell concept), including macro sites operating in co-operation with smaller stations and employing a variety of radio technologies depending on service needs, use cases and/or spectrum available. 5G mobile communications may support a wide range of use cases and related applications including video streaming, augmented reality, different ways of data sharing and various forms of machine type applications (such as (massive) machine-type communications (mMTC), including vehicular safety, different sensors and real-time control. 5G may be expected to have multiple radio interfaces, namely below 6GHz, cmWave and mmWave, and also being integradable with existing legacy radio access technologies, such as the LTE. Integration with the LTE may be implemented, at least in the early phase, as a system, where macro coverage may be provided by the LTE, and 5G radio interface access may come from small cells by aggregation to the LTE. In other words, 5G may support both inter-RAT operability (such as LTE-5G) and inter-Rl operability (inter-radio interface operability, such as below 6GHz - cmWave, below 6GHz - cmWave - mmWave). One of the concepts considered to be used in 5G networks may be network slicing in which multiple independent and dedicated virtual sub-networks (network instances) may be created within the same infrastructure to run services that have different requirements on latency, reliability, throughput and mobility.

The current architecture in LTE networks may be fully distributed in the radio and fully centralized in the core network. The low latency applications and services in 5G may require to bring the content close to the radio which leads to local break out and multi-access edge computing (MEC). 5G may enable analytics and knowledge generation to occur at the source of the data. This approach may require leveraging resources that may not be continuously connected to a network such as laptops, smartphones, tablets and sensors. MEC may provide a distributed computing environment for application and service hosting. It may also have the ability to store and process content in close proximity to cellular subscribers for faster response time. Edge computing may cover a wide range of technologies such as wireless sensor networks, mobile data acquisition, mobile signature analysis, cooperative distributed peer-to-peer ad hoc networking and processing also classifiable as local cloud/fog computing and grid/mesh computing, dew computing, mobile edge computing, cloudlet, distributed data storage and retrieval, autonomic self-healing networks, remote cloud services, augmented and virtual reality, data caching, Internet of Things (massive connectivity and/or latency critical), critical communications (autonomous vehicles, traffic safety, real-time analytics, time-critical control, healthcare applications).

The communication system may also be able to communicate with other networks, such as a public switched telephone network or the Internet 112, or utilize services provided by them. The communication network may also be able to support the usage of cloud services, for example at least part of core network operations may be carried out as a cloud service (this is depicted in FIG. 1 by "cloud" 114). The communication system may also comprise a central control entity, or a like, providing facilities for networks of different operators to cooperate for example in spectrum sharing.

Edge cloud may be brought into radio access network (RAN) by utilizing network function virtualization (NVF) and software defined networking (SDN). Using edge cloud may mean access node operations to be carried out, at least partly, in a server, host or node operationally coupled to a remote radio head or base station comprising radio parts. It may also be possible that node operations will be distributed among a plurality of servers, nodes or hosts. Application of cloudRAN architecture may enable RAN real time functions being carried out at the RAN side (in a distributed unit, DU 104) and non-real time functions being carried out in a centralized manner (in a centralized unit, CU 108).

It should also be understood that the distribution of labour between core network operations and base station operations may differ from that of the LTE or even be non-existent. Some other technology advancements that may be used may be Big Data and all-IP, which may change the way networks are being constructed and managed. 5G (or new radio, NR) networks may be designed to support multiple hierarchies, where MEC servers may be placed between the core and the base station or nodeB (gNB). It should be appreciated that MEC may be applied in 4G networks as well.

5G may also utilize satellite communication to enhance or complement the coverage of 5G service, for example by providing backhauling. Possible use cases may be providing service continuity for machine-to-machine (M2M) or Internet of Things (loT) devices or for passengers on board of vehicles, or ensuring service availability for critical communications, and future railway/maritime/aeronautical communications. Satellite communication may utilize geostationary earth orbit (GEO) satellite systems, but also low earth orbit (LEO) satellite systems, in particular mega-constellations (systems in which hundreds of (nano) satellites are deployed). Each satellite 106 in the mega-constellation may cover several satellite-enabled network entities that create on-ground cells. The on- ground cells may be created through an on-ground relay node 104 or by a gNB located on- ground or in a satellite.

It is obvious for a person skilled in the art that the depicted system is only an example of a part of a radio access system and in practice, the system may comprise a plurality of (e/g)NodeBs, the user device may have an access to a plurality of radio cells and the system may also comprise other apparatuses, such as physical layer relay nodes or other network elements, etc. At least one of the (e/g)NodeBs or may be a Home(e/g)nodeB. Additionally, in a geographical area of a radio communication system, a plurality of different kinds of radio cells as well as a plurality of radio cells may be provided. Radio cells may be macro cells (or umbrella cells) which may be large cells having a diameter of up to tens of kilometers, or smaller cells such as micro-, femto- or picocells. The (e/g)NodeBs of FIG. 1 may provide any kind of these cells. A cellular radio system may be implemented as a multilayer network including several kinds of cells. In multilayer networks, one access node may provide one kind of a cell or cells, and thus a plurality of (e/g)NodeBs may be required to provide such a network structure.

For fulfilling the need for improving the deployment and performance of communication systems, the concept of "plug-and-play" (e/g)NodeBs may be introduced. A network which may be able to use "plug-and-play" (e/g)Node Bs, may include, in addition to Home (e/g)NodeBs (H(e/g)nodeBs), a home node B gateway, or HNB-GW (not shown in FIG. 1). A HNB Gateway (HNB-GW), which may be installed within an operator’s network, may aggregate traffic from a large number of HNBs back to a core network.

FIG. 2 illustrates an exemplary embodiment of a non-terrestrial network. A non-terrestrial network may refer to a network, or a segment of networks, using radio frequency, RF, resources in a satellite 201, or an unmanned aircraft system, UAS. The satellite 201, or UAS, may provide service, for example NR service, on Earth via one or more satellite beams and one or more cells 202, for example NR cells, over a given service area bounded by the field of view of the satellite 201. The beam footprints, i.e. the cells 202, may be elliptical in shape. There may be a service link 210, i.e. a radio link, between the satellite 201 and one or more UEs 203 within the targeted service area. The satellite may be configured to transmit one or more signals to the one or more UEs via the service link, and the one or more UEs may be configured to receive the one or more signals from the satellite. Furthermore, there may be a feeder link 211, i.e. a radio link, between the satellite 201 and one or more satellite gateways 204. The satellite gateway 204 may connect the satellite for example to a public data network 205. The satellite 201, the gateway 204, and/or the data network 205 may comprise base station functionalities, for example gNB functionalities, at least partially. The satellite 201 may implement a transparent payload with radio frequency filtering, frequency conversion and amplification, wherein the waveform signal repeated by the payload is unchanged. Alternatively, the satellite 201 may implement a regenerative payload with radio frequency filtering, frequency conversion and amplification, as well as demodulation and/or decoding, switch and/or routing, and coding and/or modulation. In other words, in the regenerative architecture, the satellite 201 may comprise all or at least some base station functionalities. The satellite 201 may be, for example, in low Earth orbit at an altitude between 400 to 2000 km, as a non-limiting example. At such an altitude, the satellite may be moving at approximately 7.5 km/s relative to Earth. A UAS may operate for example at an altitude between 8 to 50 km, and it may be stationary or moving relative to the Earth.

FIG. 3 illustrates an exemplary embodiment of a non-terrestrial network with Earth-fixed cells using steerable satellite beams with dynamically adjusted pointing direction. In this exemplary embodiment, a satellite 301 may continuously adjust the satellite beam pointing direction to fix a location of a cell 302 and a beam, for example a NR cell and a NR beam, to a specific position on Earth, while the satellite 301 itself is moving.

Alternatively, the satellite beam pointing direction may be fixed, and thus the beam footprint, for example a NR cell, may be moving on Earth as the satellite is moving.

Full coverage over large geographical areas may require a large number of satellite cells, for example dozens of cells, even with a cell diameter of 100 km, as an example. A continuous satellite beam-shaping, for example beam width and/or orientation adjustment, mechanism may be beneficial in order to maintain a reasonably stable coverage area while the satellite is moving above the area of interest, until the area is switched, or handed, over to the next satellite. Furthermore, for a non-terrestrial network with Earth-fixed cells, the satellite beam-shaping capabilities may be limited by the physical construction of the antenna system on board the satellite, such as the antenna array size, number of antenna panels, etc. For example, higher altitude LEO satellites may be larger in size, and thus may possibly accommodate larger antenna arrays and have more signal processing power and/or capabilities.

Considering the practicalities and possible imperfections of beam-shaping, these may result in dynamic, i.e. continuously changing, inter-cell interference conditions, as illustrated in FIG. 4. FIG. 4 illustrates continuously changing cell-edge interference conditions that may be experienced by a UE with Earth-fixed cells. Referring to FIG. 4, block 410 illustrates a reference coverage footprint at a first time instant with a satellite at a 90 degree elevation angle, wherein a UE 411 is in cell edge conditions. In this scheme, cell-edge borders may be minimized and uniform.

Block 420 in FIG. 4 illustrates coverage footprint at a second time instant with a satellite at a 60 degree elevation angle and Earth rotation, with beam-shaping applied. A UE 421 is in cell edge conditions in this scheme as well. The arrow 422 illustrates the satellite visibility direction. In this case, the beam footprints, i.e. cells, are distorted due to the lower satellite elevation angle and Earth curvature. The cell-edge borders have shifted and the cell-edge areas have increased, but may still be uniform if beam-shaping is applied to all beams. In terrestrial networks, for example inter-cell interference coordination, ICIC, enhanced inter-cell interference coordination, elCIC, or further enchanced inter-cell interference coordination, felCIC, may be used to mute the neighbour cells and mitigate, or cancel, interference at the UE side, with or without network assistance. However, nonterrestrial networks may involve quickly and continuously changing cell-edge conditions even for non-moving UEs, combined with large signalling delays, since large propagation paths may result in a large round-trip time. Therefore, it may be beneficial to provide an interference mitigation scheme, which relies less on signalling between a UE and a gNB.

Some exemplary embodiments may provide an apparatus, for example a UE, with a capability to autonomously mitigate the impact of interference variations for example in situations, where the apparatus experiences continuously changing cell-edge areas with significant inter-cell intra-satellite interference. The apparatus may monitor and store the elevation angle of the serving satellite, as well as the inter-cell intra-satellite intra-frequency interference levels, and then estimate an interference margin metric and/or channel quality gradient, i.e. change rate, or trend, to adjust the sampling rate for the interference measurements. The apparatus may then perform interference mitigation based on the estimated average interference trend for example by pre-emptively postponing, or timing, uplink scheduling requests. The estimated average interference trend may further allow the apparatus to determine a frequency reuse deployment scheme at the gNB or satellite without any explicit signalling from the network. The apparatus may also apply adjusted interference cancellation towards the neighbouring cells for example by biasing the channel covariance matrix and/or by adjusting the antenna beams used for transmission and/or reception. In addition, the estimated slope of the average interference trend may be used to pre-emptively prepare for a conditional handover.

FIG. 5 illustrates a flow chart according to an exemplary embodiment. The functions illustrated in FIG. 5 may be performed by an apparatus such as a UE, which may also be referred to as a terminal device. In block 501, one or more interference values towards the serving cell are estimated based on radio measurements from two or more neighbour intra-frequency cells. The interference may be estimated by using one or more interference metrics, such as signal-to-interference-plus-noise ratio, S1NR, reference signal received power, RSRP, reference signal received quality, RSRQ, and/or received signal strength indicator, RSS1. The two or more cells may be selected autonomously by the apparatus, and the one or more interference values may be estimated, or collected, autonomously by the apparatus even without any network configuration. The interference estimation may be performed periodically at a pre-defined time interval.

In block 502, the elevation angle of the serving satellite or UAS is estimated periodically. In block 503, the estimated interference values and the elevation angle values during a past time window are stored for example in an internal database of the apparatus, while being served by the same satellite or cell. A pre-defined interference threshold value, for example a S1NR threshold value, may be used to trigger storing of the information. For example, if the apparatus is in the center of a beam with a high S1NR value indicating low interference, i.e. the S1NR is above the threshold, the apparatus may switch off the storing or store the information less frequently. The past time window may be adjusted for example based on the satellite ephemeris, i.e. trajectory, and/or frequency bands.

In block 504, the range and the change rate, for example a gradient or trend, of the interference is estimated based on the stored information during the past time window. The past time window may be, for example, 10-20 seconds in order to determine the change rate for the current serving satellite or cell. The estimation may be performed periodically or continuously.

In order to estimate the interference range, the estimated interference values during the past time window may be compared for example relative to one or more predefined interference threshold values, or relative to one or more pre-defined interference ranges by determining if the estimated interference values are for example between a predefined minimum and maximum limit. The estimated interference range may indicate whether the interference is at a high, medium or low level, for example. As a non-limiting example, the interference values may be estimated to be in a high range if S1NR is below 0 dB, in a medium range if S1NR is between 0 and 5 dB, or in a low range if S1NR is above 5 dB. The estimated interference range may be used for estimating the interference change rate.

The interference change rate indicates a change, for example an increase or a decrease, in the magnitude of interference as a function of the satellite elevation angle and/or time. The interference change rate may be determined for example by dividing the difference in the magnitude of interference between a first time instant and a second time instant by the difference between the first time instant and the second time instant. For example, the first time instant may be the start of the past time window, and the second time instant may be the end of the past time window. The interference change rate may be measured for example as dB/s.

The rate at which the interference is changing may be used to determine a suitable measurement rate for the interference estimations. In other words, the time interval for performing the interference estimations may be adjusted to increase or decrease the sampling rate of the measurements. The measurement sampling rate may be based on, for example, the rate at which the S1NR is changing. The interference gradient, or trend, may also be compared to previously recorded gradients, or trends, since the patterns may repeat themselves for example in the case of a non-moving UE as the satellite moves in a fixed, or deterministic, orbit. The non-moving UE may still be moving relative to the satellite orbit due to the rotation of the Earth, which is also deterministic movement. If the estimated interference, measured for example as S1NR, fits a previously estimated interference curve, for example S1NR curve, the measurement sampling rate may be lowered, and further measurements may be used to check if the same curve is being followed.

In block 505, it is evaluated if the estimated interference range is a high interference range, i.e. if the estimated interference values during the past time window are at least partially within a pre-defined high interference range for example based on a pre-defined threshold value. If the estimated interference values are within the predefined high interference range at least partially, the interference level may be considered to be high. In blocks 506 and 511, it is also evaluated if the change rate of the interference is above a pre-defined threshold value. The pre-defined threshold value for the change rate may be based on the estimated interference range, for example. The pre-defined threshold value for the change rate may also be adjusted for example based on the satellite ephemeris, i.e. trajectory, and/or frequency bands.

If the interference is within the pre-defined high range (505: yes) and the change rate is above the pre-defined threshold value (506: yes), in block 507 it is determined that frequency domain interference mitigation, for example frequency reuse, is applied at the satellite or gNB. In block 508, interference rejection combining, IRC, receiver parameters are adapted for example by performing covariance matrix estimation over a shorter time period, which may be referred to as a first time period, and/or by decreasing beam width to a narrower beam width, which may be referred to as a first beam width. For example, the first time period may be set as the shortest possible time period, and the first beam width may be set as the narrowest possible beam width. IRC may be used to subtract interference from the received signal. Covariance matrix estimation may be used for example in IRC receiver algorithms to estimate the spatial interference power distribution in the signal domain. The longer the time window used for collecting the signal samples is, the more averaging is included in the covariance matrix estimation. The process may be iterative so that after block 508 it returns to block 501, wherein interference is estimated for another time window, and continues from there.

If the interference is within the pre-defined high range (505: yes) and the change rate is not above the pre-defined threshold value (506: no), in block 509 it is determined that frequency domain interference mitigation, for example frequency reuse, is not applied at the satellite or gNB. In block 510, the IRC receiver parameters are adapted for example by performing covariance matrix estimation over a shorter time period, which may be referred to as a second time period, and/or by decreasing beam width to a narrower beam width, which may be referred to as a second beam width. It should be noted that the second time period may be longer than the first time period, and the second beam width may be larger than the first beam width. The process may be iterative so that after block 510 it returns to block 501, wherein interference is estimated for another time window, and continues from there.

If the interference is not within the pre-defined high range (505: no) and the change rate is above the pre-defined threshold value (506: yes), in block 512 it is determined that frequency domain interference mitigation, for example frequency reuse, is applied at the satellite or gNB. In block 513, the IRC receiver parameters are relaxed for example by performing covariance matrix estimation over a longer time period, which may be referred to as a third time period, and/or by increasing beam width to a wider beam width, which may be referred to as a third beam width. It should be noted that the third time period may be longer than the second time period, and the third beam width may be wider than the second beam width. The process may be iterative so that after block 513 it returns to block 501, wherein interference is estimated for another time window, and continues from there.

If the interference is not within the pre-defined high range (505: no) and the change rate is not above the pre-defined threshold value (506: no), in block 514 it is determined that frequency domain interference mitigation, for example frequency reuse, is applied at the satellite or gNB. In block 515, the IRC receiver parameters are relaxed for example by performing covariance matrix estimation over a longer time period, which may be referred to as a fourth time period, and/or by increasing beam width to a wider beam width, which may be referred to as a fourth beam width. It should be noted that the fourth time period may be longer than the third time period, and the fourth beam width may be wider than the third beam width. For example, the fourth time period may be set as the longest possible time period, and the fourth beam width may be set as the widest possible beam width. The process may be iterative so that after block 515 it returns to block 501, wherein interference is estimated for another time window, and continues from there.

In another exemplary embodiment, a static, i.e. non-moving, apparatus may be in the center of a beam. In this case, the interference estimates may not be needed, since the S1NR may be sufficient at all times, or almost at all times, while the apparatus stays in the center of the beam. Thus, a pre-defined threshold value for example for S1NR may be used to turn off the interference measurements or to reduce the measurement rate significantly. Alternatively, a common timing advance may be broadcast for the overall cell or beam. If the differential timing advance of the common timing advance is very small, for example smaller than a pre-defined threshold value, it may be determined that the apparatus is in the center of the cell or beam, and thus the rate of the interference measurements may be reduced.

FIG. 6 illustrates a flow chart according to an exemplary embodiment for timing uplink scheduling requests. In block 601, one or more interference metrics towards the serving cell are estimated based on radio measurements from two or more neighbour intra-frequency cells. The one or more interference metrics may comprise, for example, signal-to-interference-plus-noise ratio, S1NR, reference signal received power, RSRP, reference signal received quality, RSRQ, and/or received signal strength indicator, RSS1. The two or more cells may be selected autonomously by the apparatus, and the one or more interference metrics may be estimated, or collected, autonomously by the apparatus even without any network configuration. The estimation may be performed periodically at pre-defined time intervals.

In block 602, the elevation angle of the serving satellite or UAS is estimated. In block 603, the estimated interference and elevation angle values during a past time window are stored for example in an internal database of the apparatus, while being served by the same satellite or cell. A pre-defined threshold, for example a S1NR threshold, may be used to trigger storing the information. For example, if the apparatus is in the center of a beam with a high S1NR value, i.e. above the threshold, the apparatus may switch off the storing or store the information less frequently. The past time window may be adjusted for example based on the satellite ephemeris, i.e. trajectory, and/or frequency bands.

In block 604, the gradient, i.e. change rate, or trend such as an average S1NR trend, of the interference as a function of the satellite elevation angle and/or time is estimated based on the stored information during the past time window. The past time window may be for example 10-20 seconds in order to determine the gradient for the current serving satellite or cell. The estimation may be performed periodically or continuously.

In block 605, a future time window is estimated based on the interference gradient, i.e. change rate, or trend, in order to predict when the interference will be above a pre-defined threshold. In other words, the future time window indicates the estimated time window when the interference will be above the pre-defined threshold.

In block 606, uplink scheduling request transmissions are postponed until the estimated future time window has elapsed.

In other words, the change rate may be used to determine when to transmit uplink scheduling requests to the network, for example a satellite or base station. The above exemplary embodiment may be used for example for delay tolerant data, such as an loT data report. For example, a UE may have data to send to the network, for example the satellite or base station, and predicts based on the change rate that in a future time window for example the S1NR will be higher than it is currently measuring. The UE then waits until the future time window has elapsed before transmitting the scheduling request to the network, for example the satellite or base station. The UE may then receive the uplink grant during improved radio conditions in order to ensure that the UE has a better uplink quality. The UE may also have, for example, a minimum S1NR threshold that needs to be reached before transmitting in the uplink. This minimum S1NR threshold may be learned over time by the UE or known at the time of deployment and fixed. If the UE predicts that the current satellite will move out of sight, i.e. that a handover will be performed, prior to the S1NR threshold being reached, the UE may determine to wait for another satellite before requesting uplink transmission. The UE may also determine that a higher MSC level will be possible if the scheduling request is delayed to a future time window.

FIG. 7 illustrates a flow chart according to an exemplary embodiment. Referring to FIG. 7 , an interference range and an interference change rate associated with one or more signals received from a satellite are estimated 701, wherein the interference range and the interference change rate are based on a plurality of estimated interference values that are estimated periodically at a pre-defined time interval. The time interval is then adjusted 702 based at least partly on the estimated interference range and the interference change rate.

In another exemplary embodiment, an apparatus such as a UE may adjust one or more control parameters based at least partly on the estimated interference range and the interference change rate. FIG. 8 illustrates a flow chart according to such an exemplary embodiment. Referring to FIG. 8, an interference range and an interference change rate associated with one or more signals received from a satellite are estimated 801, wherein the interference range and the interference change rate are based on a plurality of estimated interference values that are estimated periodically at a pre-defined time interval. The time interval is then adjusted 802 based at least partly on the estimated interference range and the interference change rate. Furthermore, one or more control parameters of the apparatus are adjusted 803 based at least partly on the estimated interference range and the interference change rate.

A control parameter may be defined for example as a numerical value that may be used for example for controlling one or more of the following: a transmit power level, a data rate, a scheduling request, beamforming, modulation, error coding, handovers, discontinuous reception, a power saving mode, measurement periodicity, and/or reporting periodicity.

The functions and/or steps described above by means of FIGS. 5-8 are in no absolute chronological order, and some of them may be performed simultaneously or in an order differing from the described one. Other functions and/or steps may also be executed between them or within them.

FIGS. 9a and 9b illustrate simulated measurement results for a UE according to some exemplary embodiments. When the S1NR is changing rapidly within a short time window, for example 250 ms, more frequent measurements may be beneficial in order to indicate the overall behaviour properly. On the other hand, when the S1NR is changing slowly in a short time window, less measurements may be required to estimate the change rate, or gradient, correctly. Using the instantaneous gradient as a parameter for determining the measurement rate may enable achieving the same results, while minimizing the overall number of measurements required. It should be noted that S1NR is inversely proportional to interference.

FIG. 9a illustrates three distinct cases of interference conditions. Before block 912, there is fast changing and high, or medium, interference. Therefore, it may be beneficial to decrease the time intervals for the interference measurements for example to the shortest possible setting in order to increase the accuracy of the interference mitigation at the UE. Between blocks 912 and 913, there is fast changing and low interference. Therefore, it may be beneficial to increase the time intervals for the interference measurements to be longer, since the UE may not require improved interference mitigation. After block 913, there is slowly changing and low interference. Therefore, it may be beneficial to further increase the time intervals for the interference measurements for example to the longest possible setting, since the UE may not require improved interference mitigation. In FIG. 8a, two distinct average slope values may indicate the S1NR gradient based on the measurements indicated by the trend line 911. The past time window may be 10 seconds, a first estimated S1NR gradient may be approximately 0.5 dB/s at block 912, a first S1NR range may be -5 to +5 dB, a second estimated S1NR gradient may be approximately 0.15 dB/s at block 913, and a second S1NR range may be +5 to +15 dB. Since the trend comprises a large slope followed by a low slope, it may be determined that frequency domain interference mitigation is applied at the satellite or gNB.

FIG. 9b illustrates an exemplary embodiment, where frequency reuse is not deployed, resulting in slowly changing and high interference. Therefore, it may be beneficial to decrease the time intervals of the interference measurements in order to increase the accuracy of the interference mitigation at the UE. In this exemplary embodiment, one average slope value may indicate the S1NR trend based on the measurements indicated by the trend line 921. The past time window may be 10 seconds, the estimated S1NR gradient may be approximately 0.25 dB/s at block 922, and the S1NR range may be -5 to +5 dB. Since the average trend slope is small, it may be determined that frequency domain interference mitigation is not applied at the satellite or gNB. A technical advantage provided by some exemplary embodiments may be that they may improve timing of delay-tolerant user plane uplink transmissions without signalling overhead, thus reducing power consumption. In addition, some exemplary embodiments may enable improved and autonomous interference mitigation, or cancellation, by the device without signalling overhead. Furthermore, the device may autonomously adapt to interference mitigation setup changes on the satellite or base station, such as a switch of frequency reuse, cell beam-shaping, etc. Some exemplary embodiments, for example the exemplary embodiment illustrated in FIG. 6, may reduce the number of retransmissions, which may result in power savings, and/or increase the data rate during uplink transmissions. The uplink link budget may be limited for example for non-terrestrial network devices and loT devices, which may have a limited number of antennas, and thus it may be beneficial to improve the uplink efficiency for such devices.

FIG. 10 illustrates an apparatus 1000, which may be an apparatus such as, or comprised in, a terminal device, which may also be referred to as a UE, according to an exemplary embodiment. The apparatus 1000 comprises a processor 1010. The processor 1010 interprets computer program instructions and processes data. The processor 1010 may comprise one or more programmable processors. The processor 1010 may comprise programmable hardware with embedded firmware and may, alternatively or additionally, comprise one or more application specific integrated circuits, ASICs.

The processor 1010 is coupled to a memory 1020. The processor is configured to read and write data to and from the memory 1020. The memory 1020 may comprise one or more memory units. The memory units may be volatile or non-volatile. It is to be noted that in some exemplary embodiments there may be one or more units of nonvolatile memory and one or more units of volatile memory or, alternatively, one or more units of non-volatile memory, or, alternatively, one or more units of volatile memory. Volatile memory may be for example RAM, DRAM or SDRAM. Non-volatile memory may be for example ROM, PROM, EEPROM, flash memory, optical storage or magnetic storage. In general, memories may be referred to as non-transitory computer readable media. The memory 1020 stores computer readable instructions that are executed by the processor 1010. For example, non-volatile memory stores the computer readable instructions and the processor 1010 executes the instructions using volatile memory for temporary storage of data and/or instructions.

The computer readable instructions may have been pre-stored to the memory 1020 or, alternatively or additionally, they may be received, by the apparatus, via an electromagnetic carrier signal and/or may be copied from a physical entity such as a computer program product. Execution of the computer readable instructions causes the apparatus 1000 to perform one or more of the functionalities described above.

In the context of this document, a "memory" or "computer-readable media" or "computer-readable medium" may be any non-transitory media or medium or means that can contain, store, communicate, propagate or transport the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer.

The apparatus 1000 may further comprise, or be connected to, an input unit 1030. The input unit 1030 may comprise one or more interfaces for receiving input. The one or more interfaces may comprise for example one or more temperature, motion and/or orientation sensors, one or more cameras, one or more accelerometers, one or more microphones, one or more buttons and/or one or more touch detection units. Further, the input unit 1030 may comprise an interface to which external devices may connect to.

The apparatus 1000 may also comprise an output unit 1040. The output unit may comprise or be connected to one or more displays capable of rendering visual content such as a light emitting diode, LED, display, a liquid crystal display, LCD and a liquid crystal on silicon, LCoS, display. The output unit 1040 may further comprise one or more audio outputs. The one or more audio outputs may be for example loudspeakers.

The apparatus 1000 further comprises a connectivity unit 1050. The connectivity unit 1050 enables wireless connectivity to one or more external devices. The connectivity unit 1050 comprises at least one transmitter and at least one receiver that may be integrated to the apparatus 1000 or that the apparatus 1000 may be connected to. The at least one transmitter comprises at least one transmission antenna, and the at least one receiver comprises at least one receiving antenna. The connectivity unit 1050 may comprise an integrated circuit or a set of integrated circuits that provide the wireless communication capability for the apparatus 1000. Alternatively, the wireless connectivity may be a hardwired application specific integrated circuit, ASIC. The connectivity unit 1050 may comprise one or more components such as a power amplifier, digital front end, DFE, analog-to-digital converter, ADC, digital-to-analog converter, DAC, frequency converter, (de) modulator, and/or encoder/decoder circuitries, controlled by the corresponding controlling units.

It is to be noted that the apparatus 1000 may further comprise various components not illustrated in FIG. 10. The various components may be hardware components and/or software components.

The apparatus 1100 of FIG. 11 illustrates an exemplary embodiment of an apparatus such as, or comprised in, a satellite, a UAS, or a base station such as a gNB. The apparatus may comprise, for example, a circuitry or a chipset applicable for realizing some of the described exemplary embodiments. The apparatus 1100 maybe an electronic device comprising one or more electronic circuitries. The apparatus 1100 may comprise a communication control circuitry 1110 such as at least one processor, and at least one memory 1120 including a computer program code (software) 1122 wherein the at least one memory and the computer program code (software) 1122 are configured, with the at least one processor, to cause the apparatus 1100 to carry out some of the exemplary embodiments described above.

The memory 1120 may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The memory may comprise a configuration database for storing configuration data. For example, the configuration database may store a current neighbour cell list, and, in some exemplary embodiments, structures of the frames used in the detected neighbour cells.

The apparatus 1100 may further comprise a communication interface 1130 comprising hardware and/or software for realizing communication connectivity according to one or more communication protocols. The communication interface 1130 may provide the apparatus with radio communication capabilities to communicate in the cellular communication system. The communication interface may, for example, provide a radio interface to terminal devices. The apparatus 1100 may further comprise another interface towards a core network, such as to a gateway, a network coordinator apparatus and/or an access nodes of a cellular communication system. The apparatus 1100 may further comprise a scheduler 1140 that is configured to allocate resources.

As used in this application, the term "circuitry" may refer to one or more or all of the following: a. hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry) and b. combinations of hardware circuits and software, such as (as applicable): i. a combination of analog and/or digital hardware circuit(s) with software/firmware and ii. any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone, to perform various functions) and c. hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (for example firmware) for operation, but the software may not be present when it is not needed for operation.

This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

The techniques and methods described herein may be implemented by various means. For example, these techniques may be implemented in hardware (one or more devices), firmware (one or more devices), software (one or more modules), or combinations thereof. For a hardware implementation, the apparatus (es) of exemplary embodiments may be implemented within one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), graphics processing units (GPUs), processors, controllers, micro-controllers, microprocessors, other electronic units designed to perform the functions described herein, or a combination thereof. For firmware or software, the implementation can be carried out through modules of at least one chipset (e.g. procedures, functions, and so on) that perform the functions described herein. The software codes may be stored in a memory unit and executed by processors. The memory unit may be implemented within the processor or externally to the processor. In the latter case, it can be communicatively coupled to the processor via various means, as is known in the art. Additionally, the components of the systems described herein may be rearranged and/or complemented by additional components in order to facilitate the achievements of the various aspects, etc., described with regard thereto, and they are not limited to the precise configurations set forth in the given figures, as will be appreciated by one skilled in the art. It will be obvious to a person skilled in the art that, as technology advances, the inventive concept may be implemented in various ways. The embodiments are not limited to the exemplary embodiments described above, but may vary within the scope of the claims. Therefore, all words and expressions should be interpreted broadly, and they are intended to illustrate, not to restrict, the exemplary embodiments.

Claims

1. An apparatus comprising at least one processor, and at least one memory including computer program code, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to: estimate an interference range and an interference change rate associated with one or more signals received from a satellite, wherein the interference range and the interference change rate are based on a plurality of estimated interference values that are estimated periodically at a pre-defined time interval; adjust the time interval based at least partly on the estimated interference range and the interference change rate.

2. An apparatus according to claim 1, wherein the apparatus is further caused to adjust one or more control parameters of the apparatus based at least partly on the estimated interference range and the interference change rate.

3. An apparatus according to any preceding claim, wherein the apparatus is further caused to estimate an elevation angle of the satellite periodically, wherein the interference change rate is estimated as a function of the elevation angle and/or time.

4. An apparatus according to any preceding claim, wherein the apparatus is further caused to store the estimated interference values and/or the estimated elevation angle, wherein the storing is triggered based on a first pre-defined interference threshold value.

5. An apparatus according to any preceding claim, wherein the apparatus is further caused to time one or more uplink scheduling requests based at least partly on the estimated interference change rate.

6. An apparatus according to any preceding claim, wherein the apparatus is further caused to determine whether interference mitigation is applied at the satellite or not based at least partly on the estimated interference range and the interference change rate.

7. An apparatus according to any preceding claim, wherein the apparatus is further caused to adjust a beam width based at least partly on the estimated interference range and the interference change rate.

8. An apparatus according to any preceding claim, wherein the apparatus is further caused to perform interference mitigation for the one or more received signals based at least partly on the estimated interference change rate.

9. An apparatus according to any preceding claim, wherein the time intervals are adjusted by: decreasing the time interval to a first time period, if the estimated interference range is at least partially within a pre-defined range and the estimated change rate exceeds a second pre-defined threshold value; decreasing the time interval to a second time period, if the estimated interference range is at least partially within the pre-defined range and the estimated change rate does not exceed the second pre-defined threshold value, wherein the second time period is longer than the first time period; increasing the time interval to a third time period, if the estimated interference range is not within the pre-defined range and the estimated change rate exceeds the second pre-defined threshold value, wherein the third time period is longer than the second time period; increasing the time interval to a fourth time period, if the estimated interference range is not within the pre-defined range and the estimated change rate does not exceed the second pre-defined threshold value, wherein the fourth time period is longer than the third time period.

10. An apparatus according to any preceding claim, wherein the plurality of interference values are estimated by using a signal-to-interference-plus-noise ratio, a reference signal received power, a reference signal received quality, and/or a received signal strength indicator.

11. An apparatus comprising means for: estimating an interference range and an interference change rate associated with one or more signals received from a satellite, wherein the interference range and the interference change rate are based on a plurality of estimated interference values that are estimated periodically at a pre-defined time interval; adjusting the time interval based at least partly on the estimated interference range and the interference change rate.

12. A system comprising at least a terminal device and a satellite; wherein the satellite is configured to: transmit one or more signals to the terminal device; wherein the terminal device is configured to: receive the one or more signals from the satellite; estimate an interference range and an interference change rate associated with the one or more signals received from the satellite, wherein the interference range and the interference change rate are based on a plurality of estimated interference values that are estimated periodically at a pre-defined time interval; adjust the time interval based at least partly on the estimated interference range and the interference change rate.

13. A system comprising at least a terminal device and a satellite; wherein the satellite comprises means for: transmitting one or more signals to the terminal device; wherein the terminal device comprises means for: receiving the one or more signals from the satellite; estimating an interference range and an interference change rate associated with the one or more signals received from the satellite, wherein the interference range and the interference change rate are based on a plurality of estimated interference values that are estimated periodically at a pre-defined time interval; adjusting the time interval based at least partly on the estimated interference range and the interference change rate.

14. A method comprising: estimating an interference range and an interference change rate associated with one or more signals received from a satellite, wherein the interference range and the interference change rate are based on a plurality of estimated interference values that are estimated periodically at a pre-defined time interval; adjusting the time interval based at least partly on the estimated interference range and the interference change rate.

15. A computer program comprising instructions for causing an apparatus to perform at least the following: estimate an interference range and an interference change rate associated with one or more signals received from a satellite, wherein the interference range and the interference change rate are based on a plurality of estimated interference values that are estimated periodically at a pre-defined time interval; adjust the time interval based at least partly on the estimated interference range and the interference change rate.