KR20240061633A - Method and apparatus for transmitting random access channel in non terrestrial network - Google Patents

Abstract

Random access channel transmission technology can be provided in non-terrestrial networks. A method of UE (user equipment), comprising: receiving RACH configuration information including information on the number of repetitions for each transmission order and information on RACH (random access channel) resources from a satellite; selecting RACH resources of the N transmission orders from the RACH configuration information; and repeating a random preamble of the selected RACH resource with a confirmed repetition number and transmitting it to the satellite, where N is a positive integer.

Description

Method and apparatus for transmitting random access channel in non-terrestrial network {METHOD AND APPARATUS FOR TRANSMITTING RANDOM ACCESS CHANNEL IN NON TERRESTRIAL NETWORK}

This disclosure relates to a random access channel transmission technology in a non-terrestrial network, and more specifically, to a random access channel transmission technology in a non-terrestrial network that repeatedly transmits a random access channel using polarization.

Communication networks (e.g., 5G communication network, 6G communication network, etc.) are being developed to provide improved communication services than existing communication networks (e.g., LTE (long term evolution), LTE-A (advanced), etc.). there is. 5G communication networks (e.g., new radio (NR) communication networks) may support frequency bands above 6 GHz as well as frequency bands below 6 GHz. In other words, the 5G communication network may support the FR1 band and/or FR2 band. The 5G communication network can support a variety of communication services and scenarios compared to the LTE communication network. For example, usage scenarios of 5G communication networks may include enhanced Mobile BroadBand (eMBB), Ultra Reliable Low Latency Communication (URLLC), massive Machine Type Communication (mMTC), etc.

The 6G communication network can support a variety of communication services and scenarios compared to the 5G communication network. 6G communication networks can meet the requirements of ultra-performance, ultra-bandwidth, ultra-space, ultra-precision, ultra-intelligence, and/or ultra-reliability. The 6G communication network can support a variety of wide frequency bands and can be applied to various usage scenarios (e.g., terrestrial communication, non-terrestrial communication, sidelink communication, etc.) .

A communication network (eg, 5G communication network, 6G communication network, etc.) may provide communication services to terminals located on the ground. The demand for communication services for not only terrestrial but also non-terrestrial airplanes, drones, and satellites is increasing, and for this purpose, technologies for non-terrestrial networks (NTN) are being discussed. . Non-terrestrial networks can be implemented based on 5G communication technology, 6G communication technology, etc. For example, in a non-terrestrial network, communication between a satellite and a communication node located on the ground or a communication node located on the non-terrestrial network (e.g., an airplane, a drone, etc.) may be performed based on 5G communication technology, 6G communication technology, etc. In a non-terrestrial network, a satellite may perform the function of a base station in a communication network (eg, 5G communication network, 6G communication network, etc.).

Meanwhile, in non-terrestrial networks, link quality may be poor due to the long distance between the satellite and the terminal, large Doppler shift due to high-speed movement, etc. In order to overcome this, it may be necessary to improve reception performance through repeated transmission of the random access channel (RACH), which is an initial access process in the uplink.

The purpose of the present disclosure to solve the above problems is to provide a random access channel transmission method and device in a non-terrestrial network that repeatedly transmits a random access channel using polarization.

In the random access channel transmission method in a non-terrestrial network according to the first embodiment of the present disclosure to achieve the above object, the method of UE (user equipment) includes information on the number of repetitions for each transmission order and RACH (random access channel) resources. Receiving RACH setting information including information about from a satellite; Determining whether the transmission order of the RA (random access) preamble is N; If the transmission order is N, checking the number of repetitions of the N transmission order in the RACH configuration information; selecting RACH resources of the N transmission orders from the RACH configuration information; And repeating the RA preamble of the selected RACH resource with a confirmed repetition number and transmitting it to the satellite, where N may be a positive integer.

Here, the number of repetitions of the N transmission order may be 2N-1 or 2×(N-1).

Here, the RACH resource for each transmission order includes information on preamble sequences for each transmission order and information on RACH occurrences for each transmission order, and the step of selecting the RACH resource for the N transmission orders from the RACH configuration information includes, selecting preamble sequences of the N transmission orders from the RACH configuration information; And it may include selecting RACH occurrences of the N transmission orders from the RACH configuration information.

Here, the UE may select a preamble sequence from preamble sequences of the N transmission orders and generate the RA preamble based on the selected preamble sequence.

Here, the RACH configuration information includes information on the polarization pattern for each transmission order, and the step of repeating the RA preamble of the selected RACH resource with a confirmed repetition number and transmitting it to the satellite includes the preamble sequences of the selected RACH resource. selecting a preamble sequence; generating the RA preamble based on the selected preamble sequence; Confirming the polarization pattern of the N transmission order; And it may include repeating the RA preamble with the confirmed repetition number using the confirmed polarization pattern and transmitting it to the satellite.

Here, if the number of repetitions for each transmission order is R, the polarization pattern for each transmission order is divided into the identification polarization pattern for each transmission order related to the repetition number of M of the RA preamble and the residual polarization pattern for each transmission order related to the repetition number of R-M of the RA preamble. The step of repeating the RA preamble using the confirmed polarization pattern with the confirmed repetition number and transmitting it to the satellite includes repeating the M corresponding to the identified polarization pattern for each transmission order of the confirmed polarization pattern. repeating the RA preamble a number of times and transmitting it to the satellite; And repeating the RA preamble with the repetition number of R-M corresponding to the residual polarization pattern for each transmission order of the confirmed polarization pattern and transmitting it to the satellite, wherein R and M are positive integers, and M may be smaller than R.

Here, the identification polarization pattern for each transmission order may be a combination of right-handed circular polarization and left-handed circular polarization, or a combination of horizontal polarization and vertical polarization.

Meanwhile, in the random access channel transmission method in a non-terrestrial network according to the second embodiment of the present disclosure to achieve the above object, as a satellite method, RACH setting information including information on the identification polarization pattern for each transmission order is transmitted to the UE ( transmitting to user equipment; Receiving RA preambles transmitted according to the RACH configuration information from the UE based on the RACH configuration information; determining an identification polarization pattern for each transmission order by checking polarization patterns of the received RA preambles; And it may include restoring the RA preamble by combining the number of RA preambles corresponding to the number of repetitions for each transmission order according to the identified polarization pattern for each transmission order.

Here, the step of restoring the RA preamble by combining the number of RA preambles corresponding to the number of repetitions for each transmission order according to the identified polarization pattern for each transmission order is to determine the number of repetitions for each transmission order according to the identified polarization pattern for each transmission order. Confirmation steps; And it may include restoring the RA preamble by combining the number of RA preambles corresponding to the number of repetitions for each confirmed transmission order.

Here, the RACH configuration information includes information on RACH occurrences for each transmission order, and the step of receiving RA preambles transmitted from the UE according to the RACH configuration information based on the RACH configuration information includes the RACH configuration information. It may include receiving the RA preambles by monitoring RACH occurrences for each transmission order according to .

Here, the identification polarization pattern for each transmission order may be a combination of right-handed circular polarization and left-handed circular polarization, or a combination of horizontal polarization and vertical polarization.

Meanwhile, in a random access channel transmission apparatus in a non-terrestrial network according to the third embodiment of the present disclosure for achieving the above object, it is a user equipment (UE) and includes at least one processor, wherein the at least one processor includes the The UE receives RACH configuration information including information on the number of repetitions for each transmission order and information on RACH (random access channel) resources from the satellite; Determine whether the transmission order of the RA (random access) preamble is N; If the transmission order is N, check the number of repetitions of the N transmission order in the RACH configuration information; select RACH resources of the N transmission orders from the RACH configuration information; And operates to cause transmission to the satellite by repeating the RA preamble of the selected RACH resource with a confirmed repetition number, where N may be a positive integer.

Here, the RACH resource for each transmission order includes information on preamble sequences for each transmission order and information on RACH occurrences for each transmission order, and in the step of selecting the RACH resource for the N transmission order from the RACH configuration information, At least one processor causes the UE to select preamble sequences of the N transmission orders from the RACH configuration information; And may operate to cause selection of RACH occurrences of the N transmission orders from the RACH configuration information.

Here, the RACH configuration information includes information on the polarization pattern for each transmission order, and in the step of repeating the RA preamble of the selected RACH resource with a confirmed repetition number and transmitting it to the satellite, the at least one processor configures the UE to: select a preamble sequence from preamble sequences of the selected RACH resource; generate the RA preamble based on the selected preamble sequence; Confirm the polarization pattern of the N transmission order; And it may operate to cause the RA preamble to be transmitted to the satellite repeatedly using the confirmed polarization pattern with the confirmed repetition number.

According to the present disclosure, the terminal can increase the number of repetitions of the preamble as the transmission order increases. Additionally, according to the present disclosure, the terminal can implicitly inform the satellite base station of information about the number of repetitions according to the transmission order using a polarization pattern. Accordingly, according to the present disclosure, the satellite base station can know the number of repetitions using the polarization pattern and can receive the preamble by combining it from the terminal.

1A is a conceptual diagram showing a first embodiment of a non-terrestrial network.
Figure 1B is a conceptual diagram showing a second embodiment of a non-terrestrial network.
Figure 2a is a conceptual diagram showing a third embodiment of a non-terrestrial network.
Figure 2b is a conceptual diagram showing a fourth embodiment of a non-terrestrial network.
Figure 2c is a conceptual diagram showing a fifth embodiment of a non-terrestrial network.
Figure 3 is a block diagram showing a first embodiment of a communication node constituting a non-terrestrial network.
Figure 4 is a block diagram showing a first embodiment of communication nodes performing communication.
Figure 5A is a block diagram showing a first embodiment of a transmission path.
Figure 5b is a block diagram showing a first embodiment of a receive path.
FIG. 6A is a conceptual diagram illustrating a first embodiment of a user plane protocol stack in a transparent payload-based non-terrestrial network.
FIG. 6B is a conceptual diagram illustrating a first embodiment of a control plane protocol stack in a transparent payload-based non-terrestrial network.
FIG. 7A is a conceptual diagram illustrating a first embodiment of a user plane protocol stack in a regenerative payload-based non-terrestrial network.
FIG. 7B is a conceptual diagram illustrating a first embodiment of a control plane protocol stack in a regenerative payload-based non-terrestrial network.
Figure 8 is a conceptual diagram showing a first embodiment of the relationship between RO (RACH occasion) and SSB (synchronization signal block) in the time-frequency domain.
Figure 9 is a flowchart showing a first embodiment of a random access channel transmission method in a non-terrestrial network.
Figure 10 is a flowchart showing a second embodiment of a random access channel transmission method in a non-terrestrial network.

Since the present disclosure can make various changes and have various embodiments, specific embodiments will be illustrated in the drawings and described in detail. However, this is not intended to limit the present disclosure to specific embodiments, and should be understood to include all changes, equivalents, and substitutes included in the spirit and technical scope of the present disclosure.

Terms such as first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another. For example, a first component may be referred to as a second component, and similarly, the second component may be referred to as a first component without departing from the scope of the present disclosure. The term “and/or” can mean any one of a plurality of related stated items or a combination of a plurality of related stated items.

In the present disclosure, “at least one of A and B” may mean “at least one of A or B” or “at least one of combinations of one or more of A and B.” Additionally, in the present disclosure, “one or more of A and B” may mean “one or more of A or B” or “one or more of combinations of one or more of A and B.”

In this disclosure, (re)transmit can mean “transmit”, “retransmit”, or “transmit and retransmit”, and (re)set can mean “set”, “reset”, or “set and reset”. can mean “connection,” “reconnection,” or “connection and reconnection,” and (re)connection can mean “connection,” “reconnection,” or “connection and reconnection.” It can mean.

When a component is said to be "connected" or "connected" to another component, it is understood that it may be directly connected to or connected to the other component, but that other components may exist in between. It should be. On the other hand, when it is mentioned that a component is “directly connected” or “directly connected” to another component, it should be understood that there are no other components in between.

The terms used in this disclosure are only used to describe specific embodiments and are not intended to limit the disclosure. Singular expressions include plural expressions unless the context clearly dictates otherwise. In the present disclosure, terms such as “comprise” or “have” are intended to designate the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, but are not intended to indicate the presence of one or more other features. It should be understood that this does not exclude in advance the possibility of the existence or addition of elements, numbers, steps, operations, components, parts, or combinations thereof.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the technical field to which this disclosure pertains. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and should not be interpreted in an idealized or overly formal sense unless explicitly defined in the present disclosure. No.

Hereinafter, preferred embodiments of the present disclosure will be described in more detail with reference to the attached drawings. In order to facilitate overall understanding in explaining the present disclosure, the same reference numerals are used for the same components in the drawings, and duplicate descriptions of the same components are omitted. In addition to the embodiments explicitly described in this disclosure, operations may be performed according to combinations of embodiments, extensions of embodiments, and/or variations of embodiments. Performance of some operations may be omitted, and the order of performance of operations may be changed.

In an embodiment, even when a method performed in a first communication node among communication nodes (e.g., transmission or reception of a signal) is described, the corresponding second communication node is similar to the method performed in the first communication node. A method (eg, receiving or transmitting a signal) may be performed. In other words, when the operation of a user equipment (UE) is described, the corresponding base station can perform an operation corresponding to the operation of the UE. Conversely, when the operation of the base station is described, the corresponding UE may perform an operation corresponding to the operation of the base station. In a non-terrestrial network (NTN) (e.g., payload-based NTN), the operation of the base station may mean the operation of the satellite, and the operation of the satellite may mean the operation of the base station. You can.

The base station is NodeB, evolved NodeB, gNodeB (next generation node B), gNB, device, apparatus, node, communication node, BTS (base transceiver station), RRH ( It may be referred to as a radio remote head (radio remote head), transmission reception point (TRP), radio unit (RU), road side unit (RSU), radio transceiver, access point, access node, etc. . UE is a terminal, device, device, node, communication node, end node, access terminal, mobile terminal, station, subscriber station, mobile station. It may be referred to as a mobile station, a portable subscriber station, or an on-broad unit (OBU).

In the present disclosure, signaling may be at least one of upper layer signaling, MAC signaling, or PHY (physical) signaling. Messages used for upper layer signaling may be referred to as “upper layer messages” or “higher layer signaling messages.” Messages used for MAC signaling may be referred to as “MAC messages” or “MAC signaling messages.” Messages used for PHY signaling may be referred to as “PHY messages” or “PHY signaling messages.” Upper layer signaling may refer to transmission and reception operations of system information (e.g., master information block (MIB), system information block (SIB)) and/or RRC messages. MAC signaling may refer to the transmission and reception operations of a MAC CE (control element). PHY signaling may refer to the transmission and reception of control information (e.g., downlink control information (DCI), uplink control information (UCI), and sidelink control information (SCI)).

In the present disclosure, “setting an operation (e.g., a transmission operation)” means “setting information (e.g., information element, parameter) for the operation” and/or “performing the operation.” This may mean that “indicating information” is signaled. “An information element (eg, parameter) is set” may mean that the information element is signaled. In this disclosure, “signal and/or channel” may mean a signal, a channel, or “signal and channel,” and signal may be used to mean “signal and/or channel.”

The communication system may be a terrestrial network, a non-terrestrial network, a 4G communication network (e.g., a long-term evolution (LTE) communication network), a 5G communication network (e.g., a new radio (NR) communication network), or It may include at least one of the 6G communication networks. Each of the 4G communication network, 5G communication network, and 6G communication network may include a terrestrial network and/or a non-terrestrial network. The non-terrestrial network may operate based on at least one communication technology among LTE communication technology, 5G communication technology, or 6G communication technology. Non-terrestrial networks can provide communication services in various frequency bands.

The communication network to which the embodiment is applied is not limited to the content described below, and the embodiment may be applied to various communication networks (eg, 4G communication network, 5G communication network, and/or 6G communication network). Here, communication network may be used in the same sense as communication system.

1A is a conceptual diagram showing a first embodiment of a non-terrestrial network.

Referring to FIG. 1A, the non-terrestrial network may include a satellite 110, a communication node 120, a gateway 130, a data network 140, etc. A unit including the satellite 110 and the gateway 130 may be a remote radio unit (RRU). The non-terrestrial network shown in FIG. 1A may be a transparent payload-based non-terrestrial network. Satellite 110 may be a low earth orbit (LEO) satellite, a medium earth orbit (MEO) satellite, a geostationary earth orbit (GEO) satellite, a high elliptical orbit (HEO) satellite, or an unmanned aircraft system (UAS) platform. The UAS platform may include a high altitude platform station (HAPS). Non-GEO satellites may be LEO satellites and/or MEO satellites.

The communication node 120 may include a communication node located on the ground (eg, UE, terminal) and a communication node located on the non-ground (eg, airplane, drone). A service link may be established between the satellite 110 and the communication node 120, and the service link may be a radio link. Satellite 110 may be referred to as an NTN payload. Gateway 130 may support multiple NTN payloads. Satellite 110 may provide communication services to communication node 120 using one or more beams. The shape of the beam reception range (footprint) of the satellite 110 may be oval or circular.

In a non-terrestrial network, three types of service links can be supported as follows:

- Earth-fixed: the service link may be provided by beam(s) that continuously cover the same geographic area at all times (e.g. Geosynchronous Orbit (GSO) satellite)

- quasi-earth-fixed: the service link may be provided by beam(s) covering one geographical area during a limited period and a different geographical area during another period (e.g. For example, non-GSO (NGSO) satellites that produce steerable beams)

- Earth-moving: The service link may be provided by beam(s) moving over the Earth's surface (e.g., an NGSO satellite producing fixed beams or non-steerable beams)

The communication node 120 may perform communication (eg, downlink communication, uplink communication) with the satellite 110 using 4G communication technology, 5G communication technology, and/or 6G communication technology. Communication between satellite 110 and communication node 120 may be performed using an NR-Uu interface and/or a 6G-Uu interface. If dual connectivity (DC) is supported, the communication node 120 may be connected to the satellite 110 as well as other base stations (e.g., base stations supporting 4G functions, 5G functions, and/or 6G functions), DC operation may be performed based on technologies defined in the 4G standard, 5G standard, and/or 6G standard.

The gateway 130 may be located on the ground, and a feeder link may be established between the satellite 110 and the gateway 130. The feeder link may be a wireless link. Gateway 130 may be referred to as a “non-terrestrial network (NTN) gateway.” Communication between the satellite 110 and the gateway 130 may be performed based on an NR-Uu interface, a 6G-Uu interface, or a satellite radio interface (SRI). The gateway 130 may be connected to the data network 140. A “core network” may exist between the gateway 130 and the data network 140. In this case, the gateway 130 may be connected to the core network, and the core network may be connected to the data network 140. The core network may support 4G communication technology, 5G communication technology, and/or 6G communication technology. For example, the core network may include an access and mobility management function (AMF), a user plane function (UPF), a session management function (SMF), etc. Communication between the gateway 130 and the core network may be performed based on the NG-C/U interface or 6G-C/U interface.

As shown in the embodiment of FIG. 1B below, a base station and a core network may exist between the gateway 130 and the data network 140 in a transparent payload-based non-terrestrial network.

Figure 1B is a conceptual diagram showing a second embodiment of a non-terrestrial network.

Referring to FIG. 1B, a gateway may be connected to a base station, the base station may be connected to a core network, and the core network may be connected to a data network. Each of the base station and core network may support 4G communication technology, 5G communication technology, and/or 6G communication technology. Communication between the gateway and the base station may be performed based on the NR-Uu interface or 6G-Uu interface, and communication between the base station and the core network (e.g., AMF, UPF, SMF) may be performed based on the NG-C/U interface or 6G-Uu interface. It can be performed based on the C/U interface.

Figure 2a is a conceptual diagram showing a third embodiment of a non-terrestrial network.

Referring to FIG. 2A, the non-terrestrial network may include satellite #1 (211), satellite #2 (212) communication node 220, gateway 230, data network 1240, etc. The non-terrestrial network shown in FIG. 2A may be a regenerative payload-based non-terrestrial network. For example, each of Satellite #1 (211) and Satellite #2 (212) receives pay received from another entity (e.g., communication node 220, gateway 230) constituting a non-terrestrial network. A regeneration operation (eg, a demodulation operation, a decoding operation, a re-encoding operation, a re-modulation operation, and/or a filtering operation) may be performed on the load, and the regenerated payload may be transmitted.

Satellite #1 (211) and Satellite #2 (212) may each be a LEO satellite, MEO satellite, GEO satellite, HEO satellite, or UAS platform. The UAS platform may include HAPS. Satellite #1 (211) may be connected to satellite #2 (212), and an inter-satellite link (ISL) may be established between satellite #1 (211) and satellite #2 (212). ISL can operate at radio frequency (RF) frequencies or optical bands. ISL can be set as optional. The communication node 220 may include a communication node located on the ground (eg, UE, terminal) and a communication node located on the non-ground (eg, airplane, drone). A service link (eg, wireless link) may be established between satellite #1 (211) and communication node 220. Satellite #1 (211) may be referred to as the NTN payload. Satellite #1 (211) may provide communication services to the communication node 220 using one or more beams.

The communication node 220 may perform communication (e.g., downlink communication, uplink communication) with satellite #1 211 using 4G communication technology, 5G communication technology, and/or 6G communication technology. Communication between satellite #1 (211) and communication node 220 may be performed using the NR-Uu interface or 6G-Uu interface. If DC is supported, communication node 220 may be connected to satellite #1 211 as well as other base stations (e.g., base stations that support 4G functionality, 5G functionality, and/or 6G functionality) and 4G specifications. , DC operation may be performed based on technologies defined in the 5G standard, and/or the 6G standard.

Gateway 230 may be located on the ground, and a feeder link may be established between satellite #1 (211) and gateway 230, and a feeder link may be established between satellite #2 (212) and gateway 230. there is. The feeder link may be a wireless link. If ISL is not set between satellite #1 (211) and satellite #2 (212), a feeder link between satellite #1 (211) and gateway 230 may be set mandatory. Communication between each of satellite #1 (211) and satellite #2 (212) and the gateway 230 may be performed based on the NR-Uu interface, 6G-Uu interface, or SRI. The gateway 230 may be connected to the data network 240.

As shown in the embodiment of FIGS. 2B and 2C below, a “core network” may exist between the gateway 230 and the data network 240.

FIG. 2B is a conceptual diagram showing a fourth embodiment of a non-terrestrial network, and FIG. 2C is a conceptual diagram showing a fifth embodiment of a non-terrestrial network.

Referring to FIGS. 2B and 2C, the gateway may be connected to the core network, and the core network may be connected to the data network. The core network may support 4G communication technology, 5G communication technology, and/or 6G communication technology. For example, the core network may include AMF, UPF, SMF, etc. Communication between the gateway and the core network can be performed based on the NG-C/U interface or 6G-C/U interface. The function of a base station may be performed by a satellite. In other words, the base station may be located on a satellite. A base station located on a satellite may be a base station-DU (distributed unit), and a base station-CU (centralized unit) may be located within NG-RAN or 6G-RAN. The payload can be processed by a base station located on the satellite. Base stations located on different satellites can be connected to the same core network. One satellite may have one or more base stations. In the non-terrestrial network of FIG. 2B, the ISL between satellites may not be set, and in the non-terrestrial network of FIG. 2C, the ISL between satellites may be set.

Meanwhile, the entities constituting the non-terrestrial network shown in FIGS. 1A, 1B, 2A, 2B, and/or 2C (e.g., satellite, base station, UE, communication node, gateway, etc.) are as follows can be configured together. In this disclosure, an entity may be referred to as a communication node.

Figure 3 is a block diagram showing a first embodiment of a communication node constituting a non-terrestrial network.

Referring to FIG. 3, the communication node 300 may include at least one processor 310, a memory 320, and a transmitting and receiving device 330 that is connected to a network and performs communication. Additionally, the communication node 300 may further include an input interface device 340, an output interface device 350, a storage device 360, etc. Each component included in the communication node 300 is connected by a bus 370 and can communicate with each other.

However, each component included in the communication node 300 may be connected through an individual interface or individual bus centered on the processor 310, rather than the common bus 370. For example, the processor 310 may be connected to at least one of the memory 320, the transmission/reception device 330, the input interface device 340, the output interface device 350, or the storage device 360 through a dedicated interface. there is.

The processor 310 may execute program commands stored in at least one of the memory 320 or the storage device 360. The processor 310 may refer to a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor on which methods according to embodiments are performed. Each of the memory 320 and the storage device 360 may be comprised of at least one of a volatile storage medium or a non-volatile storage medium. For example, the memory 320 may be comprised of at least one of read only memory (ROM) or random access memory (RAM).

Meanwhile, communication nodes that perform communication in a communication network (for example, a non-terrestrial network) may be configured as follows. The communication node shown in FIG. 4 may be a specific embodiment of the communication node shown in FIG. 3.

Figure 4 is a block diagram showing a first embodiment of communication nodes performing communication.

Referring to FIG. 4, each of the first communication node 400a and the second communication node 400b may be a base station or UE. The first communication node 400a may transmit a signal to the second communication node 400b. The transmission processor 411 included in the first communication node 400a may receive data (eg, data unit) from the data source 410. Transmitting processor 411 may receive control information from controller 416. Control information may be at least one of system information, RRC configuration information (e.g., information set by RRC signaling), MAC control information (e.g., MAC CE), or PHY control information (e.g., DCI, SCI). It can contain one.

The transmission processor 411 may generate data symbol(s) by performing processing operations (eg, encoding operations, symbol mapping operations, etc.) on data. The transmission processor 411 may generate control symbol(s) by performing processing operations (eg, encoding operations, symbol mapping operations, etc.) on control information. Additionally, the transmit processor 411 may generate synchronization/reference symbol(s) for the synchronization signal and/or reference signal.

The Tx MIMO processor 412 may perform spatial processing operations (e.g., precoding operations) on data symbol(s), control symbol(s), and/or synchronization/reference symbol(s). there is. The output (eg, symbol stream) of the Tx MIMO processor 412 may be provided to modulators (MODs) included in the transceivers 413a to 413t. A modulator (MOD) may generate modulation symbols by performing processing operations on the symbol stream, and may perform additional processing operations (e.g., analog conversion operations, amplification operations, filtering operations, upconversion operations) on the modulation symbols. A signal can be generated by performing Signals generated by the modulators (MODs) of the transceivers 413a through 413t may be transmitted through antennas 414a through 414t.

Signals transmitted by the first communication node 400a may be received at the antennas 464a to 464r of the second communication node 400b. Signals received from the antennas 464a to 464r may be provided to demodulators (DEMODs) included in the transceivers 463a to 463r. A demodulator (DEMOD) may obtain samples by performing processing operations (eg, filtering operation, amplification operation, down-conversion operation, digital conversion operation) on the signal. A demodulator (DEMOD) may perform additional processing operations on the samples to obtain symbols. MIMO detector 462 may perform MIMO detection operation on symbols. The receiving processor 461 may perform processing operations (eg, deinterleaving operations, decoding operations) on symbols. The output of receiving processor 461 may be provided to data sink 460 and controller 466. For example, data may be provided to data sink 460 and control information may be provided to controller 466.

Meanwhile, the second communication node 400b may transmit a signal to the first communication node 400a. The transmission processor 468 included in the second communication node 400b may receive data (e.g., a data unit) from the data source 467 and perform a processing operation on the data to generate data symbol(s). can be created. Transmission processor 468 may receive control information from controller 466 and may perform processing operations on the control information to generate control symbol(s). Additionally, the transmit processor 468 may generate reference symbol(s) by performing a processing operation on the reference signal.

The Tx MIMO processor 469 may perform spatial processing operations (e.g., precoding operations) on data symbol(s), control symbol(s), and/or reference symbol(s). The output (e.g., symbol stream) of the Tx MIMO processor 469 may be provided to modulators (MODs) included in the transceivers 463a to 463t. A modulator (MOD) may generate modulation symbols by performing processing operations on the symbol stream, and may perform additional processing operations (e.g., analog conversion operations, amplification operations, filtering operations, upconversion operations) on the modulation symbols. A signal can be generated by performing Signals generated by the modulators (MODs) of the transceivers 463a through 463t may be transmitted through antennas 464a through 464t.

Signals transmitted by the second communication node 400b may be received at the antennas 414a to 414r of the first communication node 400a. Signals received from the antennas 414a to 414r may be provided to demodulators (DEMODs) included in the transceivers 413a to 413r. A demodulator (DEMOD) may obtain samples by performing processing operations (eg, filtering operation, amplification operation, down-conversion operation, digital conversion operation) on the signal. A demodulator (DEMOD) may perform additional processing operations on the samples to obtain symbols. The MIMO detector 420 may perform a MIMO detection operation on symbols. The receiving processor 419 may perform processing operations (eg, deinterleaving operations, decoding operations) on symbols. The output of receive processor 419 may be provided to data sink 418 and controller 416. For example, data may be provided to data sink 418 and control information may be provided to controller 416.

Memories 415 and 465 may store data, control information, and/or program code. The scheduler 417 may perform scheduling operations for communication. The processors 411, 412, 419, 461, 468, 469 and the controllers 416, 466 shown in FIG. 4 may be the processor 310 shown in FIG. 3 and are used to perform the methods described in this disclosure. can be used

FIG. 5A is a block diagram showing a first embodiment of a transmit path, and FIG. 5B is a block diagram showing a first embodiment of a receive path.

5A and 5B, the transmit path 510 may be implemented in a communication node that transmits a signal, and the receive path 520 may be implemented in a communication node that receives a signal. The transmission path 510 includes a channel coding and modulation block 511, a serial-to-parallel (S-to-P) block 512, an Inverse Fast Fourier Transform (N IFFT) block 513, and a P-to-S (parallel-to-serial) block 514, a cyclic prefix (CP) addition block 515, and up-converter (UC) 516. The reception path 520 includes a down-converter (DC) 521, a CP removal block 522, an S-to-P block 523, an N FFT block 524, a P-to-S block 525, and a channel decoding and demodulation block 526. Here, N may be a natural number.

Information bits in the transmission path 510 may be input to the channel coding and modulation block 511. The channel coding and modulation block 511 performs coding operations (e.g., low-density parity check (LDPC) coding operations, polar coding operations, etc.) and modulation operations (e.g., low-density parity check (LDPC) coding operations, etc.) on information bits. , QPSK (Quadrature Phase Shift Keying), QAM (Quadrature Amplitude Modulation), etc.) can be performed. The output of channel coding and modulation block 511 may be a sequence of modulation symbols.

The S-to-P block 512 can convert frequency domain modulation symbols into parallel symbol streams to generate N parallel symbol streams. N may be the IFFT size or the FFT size. The N IFFT block 513 can generate time domain signals by performing an IFFT operation on N parallel symbol streams. The P-to-S block 514 may convert the output (e.g., parallel signals) of the N IFFT block 513 into a serial signal to generate a serial signal.

The CP addition block 515 can insert CP into the signal. The UC 516 may up-convert the frequency of the output of the CP addition block 515 to a radio frequency (RF) frequency. Additionally, the output of CP addition block 515 may be filtered at baseband prior to upconversion.

A signal transmitted in the transmission path 510 may be input to the reception path 520. The operation in the receive path 520 may be the reverse operation of the operation in the transmit path 510. DC 521 may down-convert the frequency of the received signal to a baseband frequency. CP removal block 522 may remove CP from the signal. The output of CP removal block 522 may be a serial signal. The S-to-P block 523 can convert serial signals into parallel signals. The N FFT block 524 can generate N parallel signals by performing an FFT algorithm. P-to-S block 525 can convert parallel signals into a sequence of modulation symbols. The channel decoding and demodulation block 526 can perform a demodulation operation on the modulation symbols and can restore data by performing a decoding operation on the result of the demodulation operation.

In FIGS. 5A and 5B, Discrete Fourier Transform (DFT) and Inverse DFT (IDFT) may be used instead of FFT and IFFT. Each of the blocks (eg, components) in FIGS. 5A and 5B may be implemented by at least one of hardware, software, or firmware. For example, in FIGS. 5A and 5B, some blocks may be implemented by software, and other blocks may be implemented by hardware or a “combination of hardware and software.” 5A and 5B, one block may be subdivided into a plurality of blocks, a plurality of blocks may be integrated into one block, some blocks may be omitted, and blocks supporting other functions may be added. It can be.

Meanwhile, NTN reference scenarios can be defined as Table 1 below.

NTN shown in Figure 1 NTN shown in Figure 2 GEO Scenario A Scenario B LEO
(adjustable beam) Scenario C1 Scenario D1 LEO (beam moving with satellite) Scenario C2 Scenario D2

If satellite 110 in the non-terrestrial network shown in FIGS. 1A and/or 1B is a GEO satellite (e.g., a GEO satellite supporting transparent functionality), this may be referred to as “Scenario A.” If satellite #1 (211) and satellite #2 (212) in the non-terrestrial network shown in FIGS. 2A, 2B, and/or 2C are each GEO satellites (e.g., GEO supporting regeneration functionality), This may be referred to as “Scenario B”.

If satellite 110 in the non-terrestrial network shown in FIGS. 1A and/or 1B is a LEO satellite with steerable beams, this may be referred to as “Scenario C1.” If satellite 110 in the non-terrestrial network shown in FIGS. 1A and/or 1B is a LEO satellite with beams moving with the satellite, this may be referred to as “Scenario C2.” If Satellite #1 (211) and Satellite #2 (212) in the non-terrestrial network shown in FIGS. 2A, 2B, and/or 2C are each LEO satellites with steerable beams, this is referred to as “Scenario D1” It can be. If Satellite #1 (211) and Satellite #2 (212) in the non-terrestrial network shown in FIGS. 2A, 2B, and/or 2C are each LEO satellites with beams moving with the satellite, this is “Scenario D2 It can be referred to as ".

Parameters for the NTN reference scenarios defined in Table 1 can be defined as Table 2 below.

Scenario A and B Scenarios C and D Altitude 35,786km 600km
1,200km Spectrum (Service Link) < 6GHz (eg, 2GHz)
> 6GHz (eg, DL 20GHz, UL 30GHz) Maximum channel bandwidth capability (service link) 30MHz for band < 6GHz
1GHz for band > 6GHz Minimum elevation angle
Maximum distance between satellite and communication node (eg, UE) at 40,581km 1,932 km (600 km altitude)
3,131km (1,200km altitude) Maximum round trip delay (RTD) (propagation delay only) Scenario A: 541.46ms (service and feeder links)

Scenario B: 270.73ms (service link only) Scenario C: (Transparent Payload: Service and Feeder Links)
- 25.77ms (600km altitude)
- 41.77ms (1200km altitude)

Scenario D: (Regeneration Payload: Service Link Only)
- 12.89ms (600km altitude)
- 20.89ms (1200km altitude) Maximum differential delay within one cell 10.3m 3.12ms (600km altitude)
3.18ms (1200km altitude) service link NR or 6G feeder link Radio interface defined in 3GPP or non-3GPP

Additionally, in the NTN reference scenario defined in Table 1, delay constraints can be defined as shown in Table 3 below.

Scenario A Scenario B Scenario C1-2 Scenario D1-2 satellite altitude 35,786km 600km Maximum RTD on the radio interface between base station and UE 541.75ms
(worst
case) 270.57ms 28.41ms 12.88ms Minimum RTD at the radio interface between base station and UE 477.14ms 238.57ms 8ms 4ms

FIG. 6A is a conceptual diagram illustrating a first embodiment of a protocol stack of the user plane in a transparent payload-based non-terrestrial network, and FIG. 6B is a transparent payload-based non-terrestrial network. This is a conceptual diagram showing a first embodiment of a control plane protocol stack in a network.

6A and 6B, user data may be transmitted and received between the UE and the core network (e.g., UPF), and control data (e.g., control information) may be transmitted and received between the UE and the core network (e.g., AMF) ) can be transmitted and received between User data and control data may each be transmitted and received via satellite and/or gateway. The protocol stack of the user plane shown in FIG. 6A can be applied identically or similarly to a 6G communication network. The protocol stack of the control plane shown in FIG. 6B can be applied identically or similarly to a 6G communication network.

FIG. 7A is a conceptual diagram illustrating a first embodiment of a protocol stack of the user plane in a non-terrestrial network based on a regeneration payload, and FIG. 7B is a first embodiment of a protocol stack of the control plane in a non-terrestrial network based on a regeneration payload. This is a conceptual diagram showing .

Referring to FIGS. 7A and 7B, each of user data and control data (eg, control information) may be transmitted and received through an interface between the UE and a satellite (eg, base station). User data may refer to a user PDU (protocol data unit). The protocol stack of a satellite radio interface (SRI) may be used to transmit and receive user data and/or control data between a satellite and a gateway. User data can be transmitted and received through a general packet radio service (GPRS) tunneling protocol (GTP)-U tunnel between the satellite and the core network.

Meanwhile, in a non-terrestrial network, a base station may transmit system information (eg, SIB19) including satellite assistance information for NTN access. The UE can receive system information (e.g., SIB19) from the base station, check satellite assistance information included in the system information, and perform communication (e.g., non-terrestrial communication) based on the satellite assistance information. can do. SIB19 may include information element(s) defined in Table 4 below.

SIB19-r17 ::= SEQUENCE {
ntn-Config-r17 NTN-Config-r17
t-Service-r17 INTEGER(0..549755813887)
referenceLocation-r17 ReferenceLocation-r17
distanceThresh-r17 INTEGER(0..65525)
ntn-NeighCellConfigList-r17 NTN-NeighCellConfigList-r17
lateNonCriticalExtension OCTET STRING
...,
[[
ntn-NeighCellConfigListExt-v1720 NTN-NeighCellConfigList-r17
]]
}

NTN-NeighCellConfigList-r17 ::= SEQUENCE (SIZE(1..maxCellNTN-r17)) OF NTN-NeighCellConfig-r17

NTN-NeighCellConfig-r17 ::= SEQUENCE {
ntn-Config-r17 NTN-Config-r17
carrierFreq-r17 ARFCN-ValueNR
physCellId-r17 PhysCellId
}

NTN-Config defined in Table 4 may include information element(s) defined in Table 5 below.

NTN-Config-r17 ::= SEQUENCE {
epochTime-r17 EpochTime-r17
ntn-UlSyncValidityDuration-r17 ENUMERATED{ s5, s10, s15, s20, s25, s30, s35, s40, s45, s50, s55, s60, s120, s180, s240, s900}
cellSpecificKoffset-r17 INTEGER(1..1023)
kmac-r17 INTEGER(1..512)
ta-Info-r17 TA-Info-r17
ntn-PolarizationDL-r17 ENUMERATED {rhcp,lhcp,linear}
ntn-PolarizationUL-r17 ENUMERATED {rhcp,lhcp,linear}
ephemerisInfo-r17 EphemerisInfo-r17
ta-Report-r17 ENUMERATED {enabled}
...
}

EpochTime-r17 ::= SEQUENCE {
sfn-r17 INTEGER(0..1023);
subFrameNR-r17 INTEGER(0..9)
}

TA-Info-r17 ::= SEQUENCE {
ta-Common-r17 INTEGER(0..66485757);
ta-CommonDrift-r17 INTEGER(-257303..257303)
ta-CommonDriftVariant-r17 INTEGER(0..28949)
}

EphemerisInfo defined in Table 5 may include information element(s) defined in Table 6 below.

EphemerisInfo-r17 ::= CHOICE {
positionVelocity-r17 PositionVelocity-r17,
orbital-r17 Orbital-r17
}

PositionVelocity-r17 ::= SEQUENCE {
positionX-r17 PositionStateVector-r17,
positionY-r17 PositionStateVector-r17,
positionZ-r17 PositionStateVector-r17,
velocityVX-r17 VelocityStateVector-r17,
velocityVY-r17 VelocityStateVector-r17,
velocityVZ-r17 VelocityStateVector-r17
}

Orbital-r17 ::= SEQUENCE {
semiMajorAxis-r17 INTEGER (0..8589934591);
eccentricity-r17 INTEGER (0..1048575);
periapsis-r17 INTEGER (0..268435455),
longitude-r17 INTEGER (0..268435455);
inclination-r17 INTEGER (-67108864..67108863);
meanAnomaly-r17 INTEGER (0..268435455)
}

PositionStateVector-r17 ::= INTEGER (-33554432..33554431)

VelocityStateVector-r17 ::= INTEGER (-131072..131071)

Meanwhile, in non-terrestrial networks, link quality may be poor due to the long distance between the satellite and the terminal, large Doppler shift due to high-speed movement, etc. To overcome this, research on coverage enhancement (CE) may be actively discussed starting with release 17. In particular, improving random access channel (RACH) performance in the uplink may be being discussed as a major issue.

In existing TN, the power ramping method may be one method for transmitting the RACH preamble. This power ramping method can improve RACH reception performance by transmitting the RACH preamble while gradually increasing terminal power.

However, in NTN, the transmission distance between satellites and terminals can be large. Therefore, even when using maximum power, it may be difficult for the satellite to successfully receive the RACH preamble transmitted from the terminal. In this way, when the terminal gradually increases the transmission power and transmits the RACH preamble using the maximum transmission power, a method to compensate for this may be needed if the RACH is not received from the satellite.

Accordingly, in NTN, the terminal can transmit the preamble repeatedly to improve reception performance of the preamble from the satellite. At this time, the satellite can receive the preamble by combining the same number of repetitions that the terminal repeatedly transmits the preamble.

At this time, the repetition number value may be fixed. Accordingly, the satellite can know the repetition number value in advance and can receive the preamble by combining it. However, if the repetition number value is fixed like this, the terminal and satellite must always use the fixed repetition number value, which can be inefficient. Accordingly, in order to utilize PRACH resources more efficiently, the terminal can gradually increase the number of repeatedly transmitted preambles as the transmission order increases. Additionally, transmission methods utilizing polarization can be utilized in a variety of ways in an NTN environment. Accordingly, if the terminal can transmit the NTN preamble using polarization, reception performance can be improved.

Meanwhile, the 94th 3GPP (3rd generation partnership project) wireless access network technology conference in December 2021 discussed the following regarding coverage improvement.

○ The goal of Release 18 NTN can be focused on applying the developed solution to NTN by improving general NR coverage.

○ The following items can be discussed as examples of areas to be considered in the next stage of research. Additionally, the Radio Access Network Technology Assembly may discuss evaluation of coverage issues specific to NTNs that have been identified as practical research topics.

- NTN-specific iterative enhancements beyond the technologies covered in Release 17's Coverage Enhancement Work Item for related channels

- NTN-specific techniques to improve diversity and/or reduce polarization loss

Meanwhile, at the 109-e meeting of Working Group (WG) 1 of the Wireless Access Network Technology General Assembly in April 2022, LG Electronics majorly identified the following regarding the initial access procedure as potential enhancement points: discussed.

○ At the Rel-17 CE (coverage enhancement) research item stage, coverage improvement for UL (uplink) signals/channels may be necessary during the initial access procedure. Therefore, both PRACH (physical random access channel) preamble repetition and PUSCH (physical uplink shared channel) repetition of Msg3 can be considered. However, due to lack of discussion time, repeated transmission of the high-priority PUSCH of Msg 3 may have been introduced preferentially in the Rel-17 CE work item stage, and repetition of the low-priority PRACH preamble may have been introduced in the Rel-17 CE work item stage. Additional transmission can be introduced. At the Rel-18 CE work item stage, suggestions can be made for improving the coverage of NR NTN.

○ It may be desirable to consider introducing both the PRACH preamble repeat and the PUSCH repeat of Msg3 in Rel-18 NTN.

○ However, since NR (new radion) does not support repeated transmission of the PRACH preamble, it may be necessary to consider the following discussions to support PRACH preamble repetition.

- First, it may be necessary to determine the maximum number of repetitions.

- NTN-specific techniques to improve diversity and/or reduce polarization loss

- Second, since the UE can be defined to repeatedly transmit the PRACH preamble through multiple ROs (RACH occasions), the reference RO can be defined so that the UE and the network use the same RA-RNTI (random access radio network temporary identifier) value. You can.

- Lastly, additional UE operation definitions may be required to determine the starting point of the random access response (RAR) window.

Meanwhile, at the 109-e meeting of Working Group 1 of the Wireless Access Network Technology Conference in April 2022, Nokia discussed the improvement of Msg 3's PUSCH as follows.

○ Msg3's PUSCH may have been found to be a coverage bottleneck in the NR system. For this reason, repetition of Msg3 may have been introduced in Rel-17 to increase the reliability of Msg3 detection and decoding.

○ The main consensus on Msg3 repeat activation can be as follows.

- The UE may request Msg3 repetition if the measured synchronization signal reference signal received quality (SS-RSRP) is less than the RSRP threshold configured through system information block (SIB)1.

- The base station can indicate the number of Msg3 repetitions using two repurposed bits from the MCS (modulation and coding scheme) field of the RAR UL grant carried in Msg2.

Meanwhile, at the 109-e meeting of Working Group 1 of the Wireless Access Network Technology General Assembly in April 2022, Sony discussed the following to improve NR NTN coverage.

○ Polarization indication for NTN communications was discussed in Rel-17, where explicit indication of polarization for DL (downlink) by the network may be supported via SIB. Meanwhile, polarization information for UL may be displayed in SIB by the network. When there is no UL polarization information, the UE can assume the same polarization for UL and DL. In terms of polarization mode, right hand circular polarization (RHCP) or left hand circular polarization (LHCP) or linear polarization type can be indicated as SIB for DL and/or UL polarization information.

○ Providing explicit information about UE capabilities may be a necessary and direct improvement to Rel-18 NTN to mitigate polarization loss.

○ For FR (frequency ranges)1 handsets, polarization generally varies depending on the UE direction, and polarization reconstruction may be difficult. Advanced very small aperture terminal (VSAT) antennas can typically change polarization automatically, and FR2's commercial handset terminals can do so as well.

Meanwhile, for initial connection, the terminal can receive system information including the following from the base station.

- Number of RACH occurrences available per SSB

- Number of available contention-based preambles

- Preamble format to use

- Frequency domain resources

- Time domain resources (slots and symbols)

- Initial power for PRACH transmission

The base station can provide RACH-related information to the terminal through SIB1 or RRC configuration through the following RACH-configuration common parameters. Table 7 below may be an example of NR RACH settings.

rach-ConfigCommon setup:
rach-ConfigGeneric
prach-ConfigurationIndex 75;
msg1-FDM one,
msg1-FrequencyStart0,
zeroCorrelationZoneConfig 0;
preambleReceivedTargetPower -109;
preambleTransMax n10,
powerRampingStep dB4,
ra-ResponseWindow sl20,
totalNumberOfRA-Preambles 8,
ssb-perRACH-OccasionAndCB-PreamblesPerSSB one:n8,
ra-ContentionResolutionTimer sf16,
prach-RootSequenceIndex l139:91,
msg1-SubcarrierSpacing kHz120,
restrictedSetConfig unrestrictedSet

Here, the prach-ConfigurationIndex field may point to a table for the RACH configuration index. These tables can define the PRACH format to use, when to send the PRACH in the time domain, and the number of RACHs available. Next, the msg1-FDM field may be the number of FDM PRACH transmissions at one time. Here, the number of transmissions can be up to 8 RACH occasions at a time. And, the msg1-FrequencyStart field may indicate the offset of the lowest PRACH transmission occurrence in the frequency domain for PRB (physical resource block) 0.

Next, the preambleTransMax field may be the maximum number of RA preamble transmissions performed before declaring failure. And, the totalNumberOfRA-Preambles field may indicate the total number of preambles available per PRACH occurrence for both contention-based and contention-free RACH. Next, the ssb-perRACH-OccasionAndCB-PreamblesPerSSB field can have two meanings. Here, ssb-perRACH-Occasion can convey information about the number of SSBs mapped per RACH occurrence. And, CB-PreamblesPerSSB can indicate the number of contention-based preambles available per SSB.

Figure 8 is a conceptual diagram showing a first embodiment of the relationship between RO (RACH occasion) and SSB (synchronization signal block) in the time-frequency domain.

Referring to FIG. 8, when the PRACH setting index is 133, six different RACH occurrences (RO) can be defined. If the number of SSBs is 1/8, one SSB can be assigned 8 consecutive RACH occasions. Here, the msg1-FDM field may be 4.

Meanwhile, the preamble transmission power P _PRACH,target of RACH Msg1 in TN can be determined by Equation 1 below.

Here, preambleReceivedTargetPower can be set by the base station in the terminal through RRC (radio resource control). Delta_Premable may depend on the PRACH preamble format. The terminal can obtain the Delta_Premable value by converting the prach-configuration Index to the preamble format and then searching in Table 8 below.

Preamble Format Delta_Premable value 0 0dB One -3dB 2 -6dB 3 0dB

Next, Preamble_Transmission_Counter may be the number of PRACH attempts, may be 1 upon initial transmission, and may increase by 1 each time upon retransmission. powerRampingStep can be configured for the UE and can be 0/2/4/6dB.

Meanwhile, in the present disclosure, when transmitting a PRACH preamble, the UE can transmit with an increased number of repetitions in the current transmission order than in the previous transmission order. Additionally, in the present disclosure, the terminal can implicitly announce the preamble transmission order using the polarization pattern used in the first N preambles. Here, the transmission order can indicate the number of transmissions: 1st transmission for the first transmission, 2nd transmission for the next transmission, 3rd transmission for subsequent transmissions, and 4th transmission for continuous transmission. It can be. And, the number of repetitions may mean the number of times the same preamble is repeatedly transmitted in each transmission order. Each transmission order and repetition number can be mapped 1:1. At this time, the preamble may be transmitted repeatedly in the time domain. The base station can restore the preamble transmitted from the terminal by repeatedly receiving and combining the preamble from the terminal. At this time, the signal-to-noise ratio (SNR) can be increased. Accordingly, preamble reception performance can be improved.

Meanwhile, considering the long delay of NTN, it may be difficult to check whether the satellite base station has received the preamble in the previous transmission order. Therefore, it may be difficult for a satellite base station to combine and receive preambles transmitted between transmission orders. As a result, improvement in reception performance through combined reception may be possible through preambles repeatedly transmitted within the same transmission order. At this time, as the transmission order increases, the terminal may increase the number of repetitions of repeated transmission within the transmission order. The mapping relationship between transmission order and repetition number may be as shown in Table 9.

transmission order Number of repetitions (R)
(Case 1) Number of repetitions (R)
(Case 2) One One One 2 2 2 3 4 4 4 8 6 .
.
. .
.
. .
.
. N R = ^2N-1 R=2×(N-1)

In case 1 of Table 9, the terminal can transmit the preamble repeatedly 2 ^N-1 times depending on the transmission order. And, in case 2 in Table 9, the terminal can increase the number of repetitions by two as the transmission order increases. At this time, the terminal can transmit the preamble at maximum transmission power. In terms of power control, the power ramping counter may be at its maximum value. In the present disclosure, if the terminal transmits the preamble at maximum power, the preamble may not be successfully received by the satellite base station. In this case, the terminal can improve the reception performance of the preamble at the satellite base station by repeatedly transmitting the preamble.

At this time, the terminal can perform preamble transmission by combining repetitive transmission and power control. This method can be easily expanded by simply combining the method disclosed in this disclosure with existing power control schemes. At this time, by setting the first transmission to n-th transmission, the terminal can transmit the preamble to the satellite base station with a repetition number greater than 1. Subsequent measures can be explained based on the settings in Table 9. Here, n may be a positive integer.

Meanwhile, the satellite base station can separately allocate and operate RACH resources by distinguishing between cases of using the transmission polarization pattern in the first transmission order and cases of using the transmission polarization pattern in the second transmission order. Here, the RACH resource may be a preamble sequence or RO. In this way, the satellite base station can distinguish resources using the preamble sequence and RO. In addition, the satellite base station can inform the terminal of the classified resource information through SIB1 and RRC reset. At this time, when there are multiple terminals, each of the terminals may support different polarization types. Accordingly, the terminal can inform the satellite base station of information about the type of polarization it can support. Then, the satellite base station can receive information about the type of polarization that can be supported from the terminal. The satellite base station can allocate RACH resources to each terminal based on information about the supportable polarization type received from the terminal.

As an example, the satellite base station may allocate part of the preamble sequence and RO to RACH resource A, and the remainder to RACH resource B. At this time, the size of each RACH resource can be determined by the satellite base station. For example, in the case of a long sequence preamble, the satellite base station can allocate PRACHRootSequenceIndex from 0 to n1 to RACH resource A. And, the satellite base station can allocate the remaining PRACHRootSequenceIndex to RACH resource B. The terminal can transmit a preamble using RACH resource A or RACH resource B.

In other words, the UE can select one preamble sequence from the preamble sequences allocated to RACH resource A. And, the terminal can generate a preamble based on the selected preamble sequence. Afterwards, the terminal can transmit the generated preamble. Likewise, the UE can select one preamble sequence from the preamble sequences allocated to RACH resource B. And, the terminal can generate a preamble based on the selected preamble sequence. Afterwards, the terminal can transmit the generated preamble.

However, the satellite base station cannot know in advance whether the terminal transmitted using RACH resource A or RACH resource B. Accordingly, the satellite base station may determine that both RACH resource A and RACH resource B are available. Accordingly, the satellite base station can monitor both RACH resources. In other words, the satellite base station cannot distinguish whether the terminal transmitted primary or secondary transmission using the polarization of the preamble transmitted the first time. Here, resource A may be a RACH resource that uses the polarization of the transmission preamble in one transmission order. And, resource B may be a RACH resource that utilizes the polarization pattern of transmission preambles in the second transmission order. Here, n1 may be a positive integer.

Meanwhile, the terminal can repeatedly transmit the preamble to the satellite base station using a polarization pattern in two or more transmission orders. At this time, the terminal may repeatedly transmit the preamble to the satellite base station with a polarization pattern mapped to each transmission order in two or more transmission orders. At this time, the terminal may apply different polarization patterns for each transmission order. In particular, the terminal may configure the first half of the polarization pattern differently for each transmission order. Here, the first half may be a pattern as shown in Table 10, which consists of polarized waves that preferentially transmit two preambles in the polarization pattern. This first half can be called an identification polarization pattern for each transmission order.

transmission order number of repetitions Repeated transmission pattern of the first two preambles (i.e., identification polarization pattern) Subsequent polarization pattern (i.e. residual polarization pattern) 2 2 L.L. 3 4 LR XX 4 6 R.L. XXXX 5 8 RR XXXXXX

Then, the satellite base station can repeatedly receive the preamble from the terminal. And, the satellite base station can find out the polarization pattern of the preambles received from the terminal. Accordingly, the satellite base station can distinguish the identification polarization pattern from the polarization pattern received from the terminal. In addition, the satellite base station can use Table 10 to find the transmission order from the identified polarization pattern and infer the number of repetitions. As an example, considering case 2 in Table 9, the satellite base station can use Table 10 to find out the number of repetitions up to 8 repeated transmissions of the preamble. At this time, in Table 10, the combination of polarization L and R used for two preamble transmissions may be the identification polarization pattern. Here, L may be left hand circular polarization (LHCP). And, R may be right hand circular polarization (RHCP). And, the preamble transmission polarization represented by “X” in Table 10 may have any polarization.

Such repeated preamble transmission can be expected to increase the reception SNR due to diversity and polarization diversity due to multiple preamble transmissions. Here, the basic assumption may be joint reception at the satellite base station of preambles repeatedly transmitted within the transmission order. Meanwhile, the satellite base station can use combination of preambles between transmission orders. However, in an NTN environment, the time interval between transmission orders can be expected to be very large. Accordingly, channel changes such as Doppler shift values may be large in an NTN environment. Additionally, in an NTN environment, the preamble may not be properly received in the previous transmission order. Accordingly, the satellite base station may not be able to easily implement combined reception of preambles between transmission orders.

Meanwhile, the identification polarization pattern that can be used for the first two transmissions can be generalized. For example, a satellite base station may implement an identification pattern using vertically polarized (V)/horizontally polarized (H) using linear polarization. Additionally, when using circular polarization, the satellite base station can set an identifying polarization pattern including polarization that uses not only L and R but also L/R simultaneously. In this case, the number of identified polarization patterns can be expanded to 3x3 = 9. Therefore, from case 2 in Table 9 to a total of 18 repeated transmissions, the terminal can implicitly inform the satellite base station of the number of repetitions.

Meanwhile, the polarization pattern excluding the identification polarization pattern from the polarization pattern (in other words, the residual polarization pattern) may be indicated by X in Table 10. This residual polarization pattern can be defined in advance between the terminal and the satellite base station. Accordingly, the satellite base station may be aware of the residual polarization pattern. If the satellite base station does not know the residual polarization pattern, blind detection can be performed for all possible polarization combinations, increasing complexity.

As an example, in the third transmission order, the residual polarization pattern can be assumed to have four cases: RR, RL, LR, and LL. If, in the third transmission order, the satellite base station does not know the residual polarization pattern used by the terminal, it may attempt to receive all residual polarization patterns. At this time, when the transmission order is 4, 16 residual polarization patterns are available to the terminal, so reception may be attempted for all residual polarization patterns. As a result, complexity can increase rapidly.

Meanwhile, the satellite base station may not accurately know the polarization pattern used by the terminal only by receiving the first two preambles. To prepare for such cases, the satellite base station can use the polarization pattern used in the first four transmissions as an identification polarization pattern to improve preamble reception performance. In this case, the satellite base station can additionally allocate RACH resources to implicitly know the number of repetitions. In other words, different RACH resources can be allocated depending on the number of initial transmissions used to find the polarization pattern. In this case, the satellite base station may additionally allocate resource C in addition to the previously set RACH resources A and B. Here, resource C may be a RACH resource that utilizes the polarization pattern of the first three transmission preambles. If the satellite base station is allocated only resources A and B, the polarization pattern of the preamble transmitted the first two times may not be known. In this case, the initial connection of the terminal may fail.

Meanwhile, the satellite base station can allocate different RACH resources depending on whether the RACH preamble is first transmitted and the number of repetitions to allow the terminal to transmit the preamble. The RACH preamble is a process that occurs before the connection between the satellite base station and the terminal is established, and the satellite base station cannot know whether the terminal transmits repeatedly. Therefore, the satellite base station can distinguish between the primary transmission case of one-time repetitive transmission and other cases using the RACH resource used by the terminal. When the terminal uses resource B, the satellite base station can find out the polarization pattern used in the terminal using the identification pattern used in the first two transmissions.

Figure 9 is a flowchart showing a first embodiment of a random access channel transmission method in a non-terrestrial network.

Referring to FIG. 9, the terminal can determine whether the transmission order is primary (S901). As a result of the determination, the terminal may increase the transmission order by 1 if it is not a primary transmission (S902). And, the terminal can transmit a preamble using resource B (S903). In contrast, if the determination result is primary transmission, the terminal can determine whether additional repeated transmission is necessary (S904). As a result of the determination, if repeated transmission is not necessary, the terminal may set the transmission order to 1 (S905). At this time, if repeated transmission is necessary, the terminal can determine the transmission order corresponding to the required repetition (S906). Then, the terminal can determine whether the transmission order is 1 (S907). As a result of the determination, if the transmission order is 1, the terminal can transmit the preamble using a specific preamble or RO allocated for primary preamble transmission (S908). Then, the satellite base station and satellite can proceed with the subsequent random access procedure. In contrast, when the transmission order is not 1, the terminal may transmit the preamble using a specific preamble or RO allocated for secondary or higher transmission of the preamble (S903). The satellite base station can receive a preamble from the terminal through a specific preamble or RO allocated for preamble secondary transmission. Then, the satellite base station and satellite can proceed with the subsequent random access procedure.

Figure 10 is a flowchart showing a second embodiment of a random access channel transmission method in a non-terrestrial network.

Referring to FIG. 10, the terminal can determine whether the transmission order is primary (S1001). As a result of the determination, if it is a primary transmission, the terminal may transmit the preamble to the satellite base station using a specific preamble or RO allocated for the preamble primary transmission (S1002). The satellite base station can receive a preamble from the terminal through a specific preamble or RO allocated for primary preamble transmission. Then, the satellite base station and satellite can proceed with the subsequent random access procedure. In contrast, in cases where it is not a primary transmission, the terminal can determine whether the transmission order n is greater than the maximum transmission order N (S1003). Here, n and N may be positive integers.

As a result of the determination, the terminal can terminate if the transmission order is greater than the maximum transmission order, and if it is not greater than the maximum transmission order, the terminal can transmit the preamble using the resources or RO allocated for preamble secondary transmission. At this time, if the transmission order is 2 (S1004), the terminal can repeatedly transmit the preamble to the satellite base station by sequentially using polarizations corresponding to the identification polarization pattern LL used for the first two repeated transmissions (S1005). The satellite base station can receive the preamble from the terminal by combining it through a specific preamble or RO allocated for preamble secondary or higher transmission. Then, the satellite base station and satellite can proceed with the subsequent random access procedure.

Meanwhile, if the transmission order is 3 (S1006), the terminal can repeatedly transmit the preamble to the satellite base station by sequentially using polarizations corresponding to the identification polarization pattern LR used for the first two repeated transmissions. Then, the preamble can be repeatedly transmitted to the base station by sequentially using polarizations corresponding to the remaining polarization pattern XX used for the remaining repeated transmissions (S1007). The satellite base station can receive the preamble from the terminal by combining it through a specific preamble or RO allocated for preamble secondary or higher transmission. Then, the satellite base station and satellite can proceed with the subsequent random access procedure.

Meanwhile, if the transmission order is 4 (S1008), the terminal can repeatedly transmit the preamble to the satellite base station by sequentially using polarizations corresponding to the identification polarization pattern RL used for the first two repeated transmissions. Then, the preamble can be repeatedly transmitted to the base station by sequentially using polarizations corresponding to the remaining polarization pattern XXX used for the remaining repeated transmissions (S1009). The satellite base station can receive the preamble from the terminal by combining it through a specific preamble or RO allocated for preamble secondary or higher transmission. Then, the satellite base station and satellite can proceed with the subsequent random access procedure.

Meanwhile, if the transmission order is 5 (S1010), the terminal can repeatedly transmit the preamble to the satellite base station by sequentially using polarizations corresponding to the identification polarization pattern RR used for the first two repeated transmissions. Then, the preamble can be repeatedly transmitted to the base station by sequentially using polarizations corresponding to the remaining polarization pattern XXXX used for the remaining repeated transmissions (S1011). The satellite base station can receive the preamble from the terminal by combining it through a specific preamble or RO allocated for preamble secondary or higher transmission. Then, the satellite base station and satellite can proceed with the subsequent random access procedure.

The operation of the method according to the present disclosure can be implemented as a computer-readable program or code on a computer-readable recording medium. Computer-readable recording media include all types of recording devices that store information that can be read by a computer system. Additionally, computer-readable recording media can be distributed across networked computer systems so that computer-readable programs or codes can be stored and executed in a distributed manner.

Additionally, computer-readable recording media may include hardware devices specially configured to store and execute program instructions, such as ROM, RAM, or flash memory. Program instructions may include not only machine language code such as that created by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like.

Although some aspects of the disclosure have been described in the context of an apparatus, it may also refer to a corresponding method description, where a block or device corresponds to a method step or feature of a method step. Similarly, aspects described in the context of a method may also be represented by corresponding blocks or items or features of a corresponding device. Some or all of the method steps may be performed by (or using) a hardware device, such as, for example, a microprocessor, programmable computer, or electronic circuit. In some embodiments, at least one more of the most important method steps may be performed by such an apparatus.

A programmable logic device (e.g., a field programmable gate array) may be used to perform some or all of the functionality of the methods described in this disclosure. A field-programmable gate array may operate in conjunction with a microprocessor to perform one of the methods described in this disclosure. In general, it is desirable for the methods to be performed by some hardware device.

Although the present disclosure has been described above with reference to preferred embodiments, those skilled in the art may modify and change the present disclosure in various ways without departing from the spirit and scope of the present disclosure as set forth in the claims below. You will understand that it is possible.

Claims (14)

As a method of user equipment (UE),
Receiving RACH configuration information including information on the number of repetitions for each transmission order and information on RACH (random access channel) resources from the satellite;
Determining whether the transmission order of the RA (random access) preamble is N;
If the transmission order is N, checking the number of repetitions of the N transmission order in the RACH configuration information;
selecting RACH resources of the N transmission orders from the RACH configuration information; and
Repeating the RA preamble of the selected RACH resource with a confirmed repetition number and transmitting it to the satellite,
N is a positive integer,
UE's method. In claim 1
The number of repetitions of the N transmission order is 2 ^N-1 or 2×(N-1),
UE's method. In claim 1,
The RACH resource for each transmission order includes information on preamble sequences for each transmission order and information on RACH occurrences for each transmission order,
The step of selecting RACH resources of the N transmission order from the RACH configuration information is,
selecting preamble sequences of the N transmission orders from the RACH configuration information; and
Comprising the step of selecting RACH occurrences of the N transmission orders from the RACH configuration information,
UE's method. In claim 3,
The UE selects a preamble sequence from preamble sequences of the N transmission order and generates the RA preamble based on the selected preamble sequence,
UE's method. In claim 1,
The RACH setting information includes information on polarization patterns for each transmission order,
The step of repeating the RA preamble of the selected RACH resource with a confirmed repetition number and transmitting it to the satellite is,
selecting a preamble sequence from preamble sequences of the selected RACH resource;
generating the RA preamble based on the selected preamble sequence;
Confirming the polarization pattern of the N transmission order; and
Comprising the step of transmitting the RA preamble to the satellite repeatedly using the confirmed polarization pattern with the confirmed repetition number,
UE's method. In claim 5,
If the number of repetitions for each transmission order is R, the polarization pattern for each transmission order consists of an identification polarization pattern for each transmission order related to the repetition number of M of the RA preamble and a residual polarization pattern for each transmission order related to the repetition number of RM of the RA preamble, ,
The step of repeatedly transmitting the RA preamble to the satellite using the confirmed polarization pattern with the confirmed repetition number,
repeating the RA preamble with the number of repetitions of the M corresponding to the identified polarization pattern for each transmission order of the confirmed polarization pattern and transmitting it to the satellite; and
Repeating the RA preamble with the number of repetitions of the RM corresponding to the residual polarization pattern for each transmission order of the confirmed polarization pattern and transmitting it to the satellite, wherein R and M are positive integers, and M is smaller than R,
UE's method. In claim 7,
The identification polarization pattern for each transmission order consists of a combination of right-handed circular polarization and left-handed circular polarization or a combination of horizontal polarization and vertical polarization,
UE's method. As a satellite method,
Transmitting RACH configuration information including information on identification polarization patterns for each transmission order to a user equipment (UE);
Receiving RA preambles transmitted according to the RACH configuration information from the UE based on the RACH configuration information;
Checking the polarization pattern of the received RA preambles to determine an identification polarization pattern for each transmission order; and
Comprising the step of restoring the RA preamble by combining the number of RA preambles corresponding to the number of repetitions for each transmission order according to the identified polarization pattern for each transmission order,
Satellite method. In claim 8,
The step of restoring the RA preamble by combining the number of RA preambles corresponding to the number of repetitions for each transmission order according to the identified polarization pattern for each transmission order,
Confirming the number of repetitions for each transmission order according to the identified polarization pattern for each transmission order; and
Comprising the step of restoring the RA preamble by combining the number of RA preambles corresponding to the number of repetitions for each confirmed transmission order,
Satellite method. In claim 8,
The RACH configuration information includes information on RACH occurrences for each transmission order,
The step of receiving RA preambles transmitted according to the RACH configuration information from the UE based on the RACH configuration information,
Comprising the step of receiving the RA preambles by monitoring RACH occurrences for each transmission order according to the RACH configuration information.
Satellite method. In claim 8,
The identification polarization pattern for each transmission order consists of a combination of right-handed circular polarization and left-handed circular polarization or a combination of horizontal polarization and vertical polarization,
Satellite method. As a UE (user equipment),
Contains at least one processor,
The at least one processor allows the UE to:
Receive RACH configuration information including information on the number of repetitions for each transmission order and information on RACH (random access channel) resources from the satellite;
Determine whether the transmission order of the RA (random access) preamble is N;
If the transmission order is N, check the number of repetitions of the N transmission order in the RACH configuration information;
select RACH resources of the N transmission orders from the RACH configuration information; and
Operate to cause transmission to the satellite by repeating the RA preamble of the selected RACH resource with an identified repetition number,
where N is a positive integer,
UE. In claim 12,
The RACH resource for each transmission order includes information on preamble sequences for each transmission order and information on RACH occurrences for each transmission order,
In the step of selecting a RACH resource of the N transmission order from the RACH configuration information, the at least one processor allows the UE to:
select preamble sequences of the N transmission orders from the RACH configuration information; and
operative to cause selection of RACH occurrences of the N transmission orders in the RACH configuration information,
UE. In claim 12,
The RACH setting information includes information on polarization patterns for each transmission order,
In the step of repeating the RA preamble of the selected RACH resource with a confirmed repetition number and transmitting it to the satellite, the at least one processor causes the UE to:
select a preamble sequence from preamble sequences of the selected RACH resource;
generate the RA preamble based on the selected preamble sequence;
Confirm the polarization pattern of the N transmission order; and
operative to cause transmission of the RA preamble to the satellite using the identified polarization pattern repeatedly with the identified number of repetitions,
UE.

Images