Patent Description:
However, as the demand for mobile broadband access continues to increase, further improvements in LTE and NR technologies remain useful.

<CIT>, relates to a random access channel generation method in a mobile communication system having a large cell area. "<NPL>, relates to packet mode for SW-CDMA (Family A).

In accordance with the independent claims, a method of wireless communication performed by a user equipment, a method of wireless communication performed by a network device, and an apparatus for performing each of the methods is provided. Further preferable aspects are provided in the dependent claims.

Rather, these aspects are provided so that this disclosure will convey the scope of the disclosure to those skilled in the art.

Furthermore, while aspects may be described herein as being used for non-terrestrial networks, aspects of the present disclosure can be applied for other forms of networks. Indeed, aspects of the present disclosure may be of particular benefit in networks associated with a large number of UEs in the coverage area of a cell.

In some aspects, as shown, a cell may be provided by a base station <NUM> of a non-terrestrial network. As used herein, a non-terrestrial network may refer to a network for which access is provided by a non-terrestrial base station, such as a base station carried by a satellite, a balloon, a dirigible, an airplane, an unmanned aerial vehicle, a high altitude platform station, and/or the like. Base station <NUM> may be part of a non-terrestrial network that is separate from wireless network <NUM>. Alternatively, the non-terrestrial network (of which base station <NUM> is a part) may be part of the wireless network <NUM>.

In one example, base station <NUM> can be an example of relay station 110d.

Wireless network <NUM> may be a heterogeneous network that includes BSs of different types, e.g., macro BSs, pico BSs, femto BSs, relay BSs, non-terrestrial BSs, and/or the like.

One or more of the operations described herein may be performed by a network device. A network device may include base station <NUM>, a core network device of a <NUM> or <NUM> network, a device of a non-terrestrial network, and/or the like.

<FIG> shows a block diagram of a design <NUM> of a base station (e.g., base station <NUM> or base station <NUM>) and UE <NUM>, which may be one of the base stations and one of the UEs in <FIG>.

Controller/processor <NUM> of base station <NUM>, controller/processor <NUM> of UE <NUM>, and/or any other component(s) of <FIG> may perform one or more techniques associated with random access for a non-terrestrial network, as described in more detail elsewhere herein. For example, controller/processor <NUM> of base station <NUM>, controller/processor <NUM> of UE <NUM>, and/or any other component(s) of <FIG> may perform or direct operations of, for example, process <NUM> of <FIG>, process <NUM> of <FIG>, and/or other processes as described herein. Memories <NUM> and <NUM> may store data and program codes for base station <NUM> and UE <NUM>, respectively. As such, memory <NUM> of the UE can comprise a non-transitory computer-readable medium storing one or more instructions for wireless communication, where the one or more instructions comprise one or more instructions that, when executed by one or more processors (e.g., receive processor <NUM> and/or controller/processor <NUM>) of the UE <NUM>, cause the one or more processors to perform the method described in greater detail with reference to <FIG>.

In some aspects, UE <NUM> may include means for receiving (e.g., using antenna <NUM>, DEMOD <NUM>, MIMO detector <NUM>, receive processor <NUM>, controller/processor <NUM>, and/or the like) or determining (e.g., using controller/processor <NUM> and/or the like) information that indicates whether to perform a first random access channel (RACH) procedure for a non-terrestrial network or a second RACH procedure for a terrestrial network, wherein the first RACH procedure is configured to support a larger number of UEs contemporaneously performing a RACH procedure than the second RACH procedure, and wherein the information is based at least in part on whether the UE is associated with the non-terrestrial network or the terrestrial network; means for selectively performing (e.g., using controller/processor <NUM>, transmit processor <NUM>, TX MIMO processor <NUM>, MOD <NUM>, antenna <NUM>, and/or the like) the first RACH procedure or the second RACH procedure in accordance with the information; means for performing (e.g., using controller/processor <NUM>, transmit processor <NUM>, TX MIMO processor <NUM>, MOD <NUM>, antenna <NUM>, and/or the like) the first RACH procedure, wherein the first RACH procedure includes a first coding procedure comprising a Zadoff-Chu coding procedure and a second coding procedure; means for receiving (e.g., using antenna <NUM>, DEMOD <NUM>, MIMO detector <NUM>, receive processor <NUM>, controller/processor <NUM>, and/or the like) an indication to perform the second coding procedure, wherein the first RACH procedure includes the second coding procedure based at least in part on the indication; means for determining (e.g., using antenna <NUM>, DEMOD <NUM>, MIMO detector <NUM>, receive processor <NUM>, controller/processor <NUM>, and/or the like) whether to perform the first RACH procedure for the non-terrestrial network or the second RACH procedure for the terrestrial network based at least in part on the information; and/or the like. In some aspects, such means may include one or more components of UE <NUM> described in connection with <FIG>.

In some aspects, base station <NUM> may include means for transmitting (e.g., using controller/processor <NUM>, transmit processor <NUM>, TX MIMO processor <NUM>, MOD <NUM>, antenna <NUM>, and/or the like) information that indicates that a user equipment (UE) is to perform a first random access channel (RACH) procedure for a non-terrestrial network, wherein the RACH procedure is configured to support a larger number of UEs contemporaneously performing a RACH procedure than a second RACH procedure for a terrestrial network; means for performing (e.g., using controller/processor <NUM>, transmit processor <NUM>, TX MIMO processor <NUM>, MOD <NUM>, antenna <NUM>, and/or the like) the first RACH procedure in accordance with the information; means for signaling a signature to be used for the second coding procedure to the UE; means for signaling (e.g., using controller/processor <NUM>, transmit processor <NUM>, TX MIMO processor <NUM>, MOD <NUM>, antenna <NUM>, and/or the like) information identifying a cover code to be used for the cover coding procedure to the UE; means for providing (e.g., using controller/processor <NUM>, transmit processor <NUM>, TX MIMO processor <NUM>, MOD <NUM>, antenna <NUM>, and/or the like) an indication that the UE is to perform the second coding procedure as part of the first RACH procedure; means for receiving (e.g., using antenna <NUM>, DEMOD <NUM>, MIMO detector <NUM>, receive processor <NUM>, controller/processor <NUM>, and/or the like) a RACH message based at least in part on a particular code, wherein the particular code is based at least in part on a beam, of the multiple beams, for which the first RACH procedure is being performed; means for determining (e.g., using controller/processor <NUM>, transmit processor <NUM>, TX MIMO processor <NUM>, MOD <NUM>, antenna <NUM>, and/or the like) whether to perform the first RACH procedure for the non-terrestrial network or the second RACH procedure for the terrestrial network based at least in part on the information; and/or the like. In some aspects, such means may include one or more components of base station <NUM> described in connection with <FIG>.

A non-terrestrial base station (referred to hereafter as a BS or a base station) may provide access to a non-terrestrial network for UEs or ground stations. As used herein, a ground station may refer to a radio station designed for communication with a non-terrestrial BS via a non-terrestrial network. A reference to a UE herein can also refer to a ground station. Furthermore, a reference to a BS can also refer to a relay station.

The BS may transmit using multiple antennas that each cover a surface area. The footprint of a beam transmitted by an antenna can be defined as a cell. A UE may acquire the BS based at least in part on searching for a synchronization signal using a spatial technique (e.g., by pointing a receive antenna beam towards the satellite), a frequency technique (e.g., by scanning different frequencies until the BS's signal is acquired), a timing technique (e.g., by searching for a starting time of a signal), a sequence-based technique (e.g., by identifying a code sequence of a synchronization signal), and/or the like. Examples of a synchronization signal include a synchronization signal block (SSB), a primary synchronization signal (PSS), a secondary synchronization signal (SSS), a physical broadcast channel (PBCH), and/or the like.

Once the UE detects a beam, the UE and the BS may perform a random access channel (RACH) procedure, such as a physical RACH (PRACH) procedure, to access the network. In the RACH procedure, the UE may transmit a RACH preamble on a particular set of resources, referred to interchangeably herein as a RACH resource or a RACH occasion. The BS may detect the RACH preamble and may transmit a response to the UE.

In a non-terrestrial network, PRACH preamble resources may be larger than in a terrestrial network, such as an LTE network or a <NUM>/NR terrestrial network. This may be due to non-terrestrial networks being associated with larger Doppler shifts (and thus a wider subcarrier spacing) and longer delays than a terrestrial network, which may necessitate a larger frequency allocation and a longer time allocation for the RACH preamble. Also, a larger number of UEs may be expected to perform handovers concurrently in a non-terrestrial network, particularly a non-terrestrial network in which the cells are in constant motion (e.g., when the cells are provided by a satellite in low earth orbit or mid earth orbit). Furthermore, the cell may be larger than a terrestrial network cell, which may mean that a larger number of UEs may be expected to perform RACH procedures on the cell.

Some techniques and apparatuses described herein provide multiplexing techniques for RACH preambles so that a number of UEs that can concurrently perform a RACH procedure is increased. For example, some techniques and apparatuses described herein provide a larger number of Zadoff-Chu shifts or roots than in a terrestrial network RACH procedure, an additional coding procedure (e.g., in addition to the Zadoff-Chu coding procedure), multiplexing of multiple RACH preambles in a single time and frequency resource, and/or the like. The UE may perform an NTN RACH procedure (such as those described above) based at least in part on an indication from a BS that the UE is to perform the NTN RACH procedure. Thus, the number of UEs that can concurrently perform a RACH procedure is increased and resource utilization is improved.

<FIG> is a diagram illustrating an example <NUM> of random access in a non-terrestrial network, in accordance with various aspects of the present disclosure. As shown, <FIG> includes a base station <NUM> (e.g., BS <NUM>, a non-terrestrial BS such as BS <NUM>, a relay station, a non-terrestrial network, and/or the like) and a UE <NUM> (e.g., UE <NUM>, a ground station, a relay station, and/or the like). Base station <NUM> is referred to hereinafter as a BS, and UE <NUM> is referred to hereinafter as a UE. In some aspects, base station <NUM> may be referred to as a network device.

As shown in <FIG>, and by reference number <NUM>, the BS may transmit an indication of whether the UE is to perform a first RACH procedure (e.g., a RACH procedure associated with a non-terrestrial network (NTN)) or a second RACH procedure (e.g., a RACH procedure not associated with an NTN, such as a RACH procedure associated with a terrestrial network). In some aspects, the indication may be transmitted using radio resource configuration (RRC) messaging, downlink control information (DCI), a media access control (MAC) control element (CE), and/or the like. In some aspects, the indication may be based at least in part on a synchronization signal block (SSB) of the UE. For example, the SSB may be associated with information identifying the indication, or may be configured in a way that provides the indication (e.g., scrambled using a particular radio temporary network identifier, provided in a time or frequency location that indicates the indication, and/or the like).

It should be understood that information for performing the first RACH procedure can be transmitted by the network, and received by the UE, in more than one transmission or message. The information for performing the first RACH procedure can include such information as that described herein, for example, Zadoff-Chu signatures used in the first RACH procedure; information for performing the first coding procedure and the second coding procedure; an indication for performing the second coding procedure; one or more time or frequency resources, one or more beams, one or more codes, one or more sets of codes, one or more subsets of the one or more sets of codes, one or more bandwidth parts, one or more resource blocks, and/or any combination thereof used in performing the first RACH procedure. In some implementations, the information that indicates whether to perform the first RACH procedure may comprise information for performing the first RACH procedure as just described such that network implicitly indicates to the UE to perform the first RACH procedure by transmitting the information for the first RACH procedure (for example, where the network does not transmit the information for the second RACH procedure). In such implementations, the UE can receive the information for performing the first RACH procedure and determine, based on this implicit indication to perform the first RACH procedure, that the UE is to perform the first RACH procedure even without an explicit indication.

As shown by reference number <NUM>, in this case, the indication may indicate that the UE and the BS are to perform an NTN RACH procedure. An NTN RACH procedure may refer to a RACH procedure wherein one or more techniques are used to increase a number of RACH preambles that can be multiplexed as part of the RACH procedure. Particular operations that can be performed as part of the NTN RACH procedure are described in more detail in connection with example <NUM> of <FIG>. In some aspects, the indication may indicate which operations are to be performed as part of the NTN RACH procedure, or may indicate parameters for the NTN RACH procedure, as is also described in more detail in connection with <FIG>. In the case when the indication indicates that the UE and the BS are to perform a terrestrial network RACH procedure, then the UE and the BS may perform a terrestrial network RACH procedure (e.g., a RACH procedure prescribed by <NUM>/NR, LTE, and/or the like).

As shown by reference number <NUM>, the UE and the BS may perform the NTN RACH procedure. For example, the UE may perform one or more of the operations described in connection with <FIG> in order to increase the number of RACH preambles that can be concurrently multiplexed. Thus, the increased number of UEs and the increased rate of handover associated with NTN may be mitigated.

In some cases, a UE and a BS are referred to herein as "performing a RACH procedure. " When a UE performs a RACH procedure, the UE may perform the UE-side steps of the RACH procedure (e.g., Messages <NUM> and <NUM> in a four-step RACH procedure or Message <NUM> in a two-step RACH procedure). When a BS performs a RACH procedure, the BS may perform the BS-side steps of the RACH procedure (e.g., Messages <NUM> and <NUM> in a four-step RACH procedure or Message <NUM> in a two-step RACH procedure).

In some aspects, the RACH preambles for multiple, different beams may be configured on the same bandwidth part (e.g., a bandwidth part of one of the multiple different beams or a bandwidth part of a beam other than the multiple, different beams). In this case, the UE may multiplex the RACH preambles of multiple different beams in a same time and/or frequency (time/frequency) resource, and may differentiate the RACH preambles of the beams in the code domain (e.g., using a Zadoff-Chu sequence, a pseudo-noise sequence, an orthogonal cover code, and/or the like). In this case, the BS may signal, per beam or per group of beams, a subset of code parameters (e.g., Zadoff-Chu shifts and/or roots, pseudo-noise shifts and/or roots, orthogonal cover code indexes, and/or the like) to be used for each beam or group of beams. Thus, different beams or groups of beams may be differentiated when RACH preambles of the beams or groups of beams are transmitted in overlapped time/frequency resources.

<FIG> is a diagram illustrating an example <NUM> of encoding and processing an NTN RACH preamble, in accordance with various aspects of the present disclosure. The operations described in connection with example <NUM> may be performed by a UE (e.g., UE <NUM>, UE <NUM>, and/or the like).

As shown in <FIG>, and by reference number <NUM>, the UE may apply a Zadoff-Chu (ZC) sequence to a set of symbols of a length LRA. This may be referred to herein as a first coding procedure. The set of symbols may form a random access (RA) preamble. In some aspects, the UE may select a ZC signature (e.g., a ZC shift and/or a ZC root) to be used to encode the preamble. In some aspects, when encoding the NTN RACH preamble, the UE may use an increased number of permitted ZC signatures relative to a terrestrial RACH procedure. According to the invention, the UE selects a ZC signature for the first coding procedure from a set of more than <NUM> possible signatures (e.g., <NUM> possible signatures, <NUM> possible signatures, or a different number of possible signatures), wherein the terrestrial RACH procedure may use a set of <NUM> possible signatures. This may increase the number of NTN RACH preambles that can be code division multiplexed with each other.

As shown by reference number <NUM>, in some aspects, the UE may perform a second coding procedure, such as a second coding procedure that does not involve a ZC code. Here, the UE performs a pseudo-noise (PN) coding procedure, although techniques and apparatuses described herein are not limited to those involving the PN coding procedure as the second coding procedure. In some aspects, the UE may select a signature (e.g., a shift, a polynomial, a root, and/or the like) for the second coding procedure. For example, the UE may select the signature randomly, pseudo-randomly, using a pattern, and/or the like, which may conserve resources of the BS that would otherwise be used to indicate the pattern. In some aspects, the UE may receive information indicating a signature that is to be used. For example, the BS may provide the information indicating the signature that is to be used, which may improve network resource utilization and conserve processor resources of the UE that would otherwise be used to select the signature.

As further shown, the UE may combine the coded outputs of the first coding procedure and the second coding procedure. As shown by reference number <NUM>, the UE may perform discrete Fourier transformation (DFT) spreading on the combined output using a size of LRA. As shown by reference number <NUM>, the UE may perform subcarrier (SC) mapping so that the transformed output is mapped to a set of frequency resources (e.g., subcarriers, symbols, and/or the like).

As shown by reference number <NUM>, in some aspects, the UE may apply orthogonal cover coding (OCC) on the set of frequency domain symbols. This may be referred to herein as a second coding procedure. In some aspects, the UE may perform a second coding procedure based at least in part on a PN sequence and based at least in part on an OCC. For example, the UE may apply the PN sequence before DFT spreading occurs, and may apply the OCC after DFT spreading occurs. As shown by reference number <NUM>, in some aspects, the UE may apply the OCC after an inverse DFT (IDFT) operation <NUM> is performed (e.g., after the symbols are converted to the time domain) and before a cyclic prefix (CP) is added at reference number <NUM>. For example, the UE may apply the OCC before the IDFT operation <NUM> is performed or after the IDFT operation <NUM> is performed. In some aspects, the UE may select a signature for the OCC. For example, the UE may select the signature randomly, pseudo-randomly, using a pattern, and/or the like, which may conserve resources of the BS that would otherwise be used to indicate the pattern. In some aspects, the UE may receive information indicating a signature that is to be used. For example, the BS may provide the information indicating the signature that is to be used, which may improve network resource utilization and conserve processor resources of the UE that would otherwise be used to select the signature.

In some aspects, the BS may provide an indication to enable or disable one or more of the above operations (e.g., indicated by reference numbers <NUM>, <NUM>, <NUM>, and/or <NUM>). For example, the BS may provide an indication of whether an increased number of ZC signatures is to be used, an indication of whether to perform a second coding procedure based at least in part on a PN sequence, an indication of whether to perform a second coding procedure based at least in part on an OCC (and/or whether the second coding procedure is to be performed before or after the IDFT operation), and/or the like. Thus, the BS may balance the complexity of encoding the NTN RACH preamble and the needs of the network (e.g., based at least in part on how many UEs are expected to contemporaneously perform a RACH operation, based at least in part on available network resources, and/or the like).

<FIG> is a diagram illustrating an example process <NUM> performed, for example, by a user equipment, in accordance with various aspects of the present disclosure. Example process <NUM> is an example where a user equipment (e.g., UE <NUM>, UE <NUM>, and/or the like) performs operations associated with random access for a non-terrestrial network.

As shown in <FIG>, in some aspects, process <NUM> may include receiving or determining information that indicates whether to perform a first random access channel (RACH) procedure for a non-terrestrial network or a second RACH procedure for a terrestrial network wherein the first RACH procedure is configured to support a larger number of UEs contemporaneously performing a RACH procedure than the second RACH procedure (block <NUM>). For example, the user equipment (e.g., using antenna <NUM>, DEMOD <NUM>, MIMO detector <NUM>, receive processor <NUM>, controller/processor <NUM>, and/or the like) may receive or determine information that indicates whether to perform a first RACH procedure for a non-terrestrial network or a second RACH procedure for a terrestrial network, as described, for example, with reference to <FIG> and <FIG>. In some aspects, the first RACH procedure is configured to support a larger number of UEs contemporaneously performing a RACH procedure than the second RACH procedure. In some aspects, the information is based at least in part on whether the UE is associated with the non-terrestrial network or the terrestrial network. Determining information that indicates to perform the first RACH procedure can include determining the information based at least in part on an implicit indication.

As further shown in <FIG>, in some aspects, process <NUM> may include, responsive to the information indicating whether to perform the first RACH procedure, performing the first RACH procedure (block <NUM>). For example, the user equipment (e.g., using controller/processor <NUM>, transmit processor <NUM>, TX MIMO processor <NUM>, MOD <NUM>, antenna <NUM>, and/or the like) may perform the first RACH procedure in accordance with the information, as described, for example, with reference to <FIG> and <FIG>.

<FIG> is a diagram illustrating an example process <NUM> performed, for example, by a network device (e.g., a base station in a non-terrestrial network), in accordance with various aspects of the present disclosure. Example process <NUM> is an example where a network device (e.g., BS <NUM>, network controller <NUM>, BS <NUM>, BS <NUM>, and/or the like) performs operations associated with random access for a non-terrestrial network.

As shown in <FIG>, in some aspects, process <NUM> may include transmitting information that indicates whether a UE is to perform a first RACH procedure for a non-terrestrial network or a second RACH procedure for a terrestrial network (block <NUM>). For example, the network device (e.g., using controller/processor <NUM>, transmit processor <NUM>, TX MIMO processor <NUM>, MOD <NUM>, antenna <NUM>, and/or the like) may transmit information that indicates whether a UE is to perform a first RACH procedure for a non-terrestrial network or a second RACH procedure for a terrestrial network, as described, for example, with reference to <FIG> and <FIG>. In some aspects, the first RACH procedure is configured to support a larger number of UEs contemporaneously performing a RACH procedure than the second RACH procedure. In some aspects, the information is based at least in part on whether the UE is associated with the non-terrestrial network or the terrestrial network.

As further shown in <FIG>, in some aspects, process <NUM> may include, when the information indicates to perform the first RACH procedure, performing the first RACH procedure in accordance with the information (block <NUM>). For example, the network device (e.g., using antenna <NUM>, DEMOD <NUM>, MIMO detector <NUM>, receive processor <NUM>, controller/processor <NUM>, and/or the like) may perform the first RACH procedure in accordance with the information, as described, for example, with reference to <FIG> and <FIG>.

However, the protection scope of this application shall be subject to the protection scope of the claims.

Claim 1:
A method (<NUM>) of wireless communication performed by a user equipment, UE (<NUM>, <NUM>), comprising:
receiving or determining (<NUM>) information (<NUM>) that indicates whether to perform a first random access channel, RACH, procedure for a non-terrestrial network or a second RACH procedure for a terrestrial network, wherein:
the first RACH procedure is configured to support a larger number of UEs contemporaneously performing a RACH procedure than the second RACH procedure; and
responsive (<NUM>) to the information (<NUM>) indicating that the UE (<NUM>, <NUM>) is to perform the first RACH procedure, performing (<NUM>) the first RACH procedure,
wherein the first RACH procedure is performed based at least in part on a Zadoff-Chu signature that is selected from more than <NUM> permitted Zadoff-Chu signatures.