WO2025152124A1

WO2025152124A1 - Methods of ntn initial access

Info

Publication number: WO2025152124A1
Application number: PCT/CN2024/073107
Authority: WO
Inventors: Chenmeng LI; Wen Tang
Original assignee: MediaTek Singapore Pte Ltd
Current assignee: MediaTek Singapore Pte Ltd
Priority date: 2024-01-18
Filing date: 2024-01-18
Publication date: 2025-07-24
Anticipated expiration: 2026-07-18

Abstract

This disclosure describes methods for the initial access of NR NTN, which are divided into 7 different methods of initial access, suitable for different use cases and/or scenarios based on the usage of different combinations of wide and narrow beams of the satellite and the beam information containers. Methods 1, 2, 3, and 4 are for UEs with GNSS capability, while Methods 5, 6, and 7 are for UEs without GNSS capability. Additionally, 3 types of beam pattern information are proposed. The beam pattern information pertains to the beams of the satellites. The content of the beam pattern information is also proposed. The 3 types of beam pattern information are intended for different use cases of satellite beams.

Description

METHODS OF NTN INITIAL ACCESS

FIELD

The invention discussed below relates generally to wireless communication, and more particularly, to methods for initial access and beam hopping of NTN.

BACKGROUND

In 5G NR, the initial access procedure is designed to enable a new user equipment (UE) to establish a connection with the network, acquire synchronization, and obtain the necessary resources to initiate communication. However, in the context of NTN, the unique characteristics of satellite communication, including the extensive beam availability and limited simultaneous beam usage, pose challenges that require specific enhancements to the initial access procedure. This disclosure addresses these challenges by proposing initial access methods optimized for NTN, ensuring efficient and reliable communication between satellites and UEs in the communication network.

Due to the extensive number of beams utilized by satellites, the initial access time for User Equipment (UE) to perform Synchronization Signal Block (SSB) blind detection can be considerably prolonged. To address this issue, several segmented and non-segmented initial access approaches using a combination of wide and narrow beams, as well as CSI-RS, is proposed in this patent.

SUMMARY

The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects, and is intended to neither identify key or critical elements of all aspects nor delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later.

In one aspect, the methods for initial access of NTN are proposed, which are divided into 7 different methods of initial access, suitable for different use case and/or scenarios.

The 1^st method of initial access is a 1-step initial access for the case of UE with GNSS capability and the narrow beam pattern information container is SIB1 and/or SIBX. The beam pattern information is type 1.

The 2^nd method of initial access is a 2-step initial access for the case of UE with GNSS capability and the narrow beam pattern information container is SIB1 and/or SIBX. The beam pattern information is type 1. No further step 2 and CSI-RS narrow beam sweeping is needed if there is no preamble#1 received by the network, thus reduce the overhead of the network/satellite.

The 3^rd method of initial access is a 2-step initial access for the case of UE with GNSS capability and the narrow beam pattern information container is Msg2a. The beam pattern information is type 2. No further step 2 and CSI-RS narrow beam sweeping is needed if there is no preamble#1 received by the network, thus reduce the overhead of the network/satellite.

The 4^th method of initial access is a 2-step initial access for the case of UE with GNSS capability and the narrow beam pattern information container is Msg2b. The beam pattern information is type 2. No further step 2 and CSI-RS narrow beam sweeping is needed if there is no preamble#1 received by the network.

The 5^th method of initial access is a 1-step initial access for the case of UE without GNSS capability and the beam pattern information is informed by the network to UEs during RRC connected mode (beam pattern information type 3) or SIB1 and/or SIBX (beam pattern information type 1) . The CSI-RS is transmitted via narrow beams of satellite. Distinct CSI-RS resources-whether in time, frequency, or code domain, or an amalgamation thereof-serve to signify the narrow beam ID information. UE acquires the satellite's narrow beam ID corresponding to its location by measuring the RSRP of the CSI-RS and/or by conducting a comparison of RSRP against a predefined threshold.

The 6^th method of initial access is a 2-step initial access for the case of UE without GNSS capability and the beam pattern information is informed by the network to UEs during RRC connected mode (beam pattern information type 3) or SIB1 and/or SIBX (beam pattern information type 1) . No further step 2 and CSI-RS narrow beam sweeping is needed if there is no preamble#1 received by the network, thus reduce the overhead of the network/satellite.

The 7^th method of initial access is for the case of UE without GNSS capability and the narrow beam pattern information type 3 is indicated by the CSI-RS, thus no specific narrow beam pattern information is added into the signalling or messages. This method has the same basic procedure of method 5 or method 6.

In another aspect, 3 types of beam pattern information is proposed. The beam pattern information is of the beams of the satellites. The beam pattern information content is also proposed. The 3 types of beam pattern information is for different use case of satellite beams.

To the accomplishment of the foregoing and related ends, the one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed figures set forth in detail certain illustrative features of the one or more aspects. These features are indicative, however, of but a few of the various ways in which the principles of various aspects may be employed, and this description is intended to include all such aspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exemplary diagram of the initial access method 1.

FIG. 2 illustrates an exemplary diagram of the initial access method 2.

FIG. 3 illustrates an exemplary diagram of the initial access method 3.

FIG. 4 illustrates an exemplary diagram of the initial access method 4.

FIG. 5 illustrates an exemplary diagram of the initial access method 5.

FIG. 6 illustrates an exemplary diagram of the initial access method 6.

FIG. 7 illustrates an exemplary diagram of the 3 types of beam pattern information.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

Several aspects of telecommunication systems will now be presented with reference to various apparatus and methods. These apparatus and methods will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, components, circuits, processes, algorithms, etc. (collectively referred to as “elements” ) . These elements may be implemented using electronic hardware, computer software, or any combination thereof. Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.

Before the description of the methods for initial access of NTN, the concept of narrow and wide beams of satellite is introduced. The satellite has wide beams and narrow beams. The coverage of wide beam is larger and the areas where different wide beams covered are or are not overlapping. The coverage of narrow beams is smaller than the wide beams and the areas where different narrow beams covered are or are not overlapping. Different set of narrow beams are within different wide beams.

Additionally, in the following context, the SIBs are divided into SIB1 and SIBX. Here, SIBX represents all SIBs other than SIB1, such as SIB19, SIB2, etc. SIBX includes one or multiple SIBs other than SIB1.

In one aspect of the disclosure, the methods for initial access of NTN are proposed, which are divided into 7 different methods of initial access, suitable for different use case and/or scenarios. More specifically, we propose to consider the following 7 alternatives:

Alternative#1: method 1 of initial access

This method is for the case of UEs with GNSS capability. For instance, a UE can determine the appropriate narrow beam of the satellite to pair with based on the acquired narrow beam pattern information. This information encompasses geographical location and coverage details corresponding to the various satellite beams. Consequently, a GNSS-enabled UE, by virtue of its self-awareness of its geographical position, can intelligently ascertain the specific narrow beam of the satellite it should align with for optimal communication.

The method 1 is a 1-step initial access, as is shown in Figure 1. The initial access procedure includes preamble, msg2, msg3 and msg4. It is performed via the wide Tx beam and narrow Rx beam of the satellite.

1. UEs attempt to camp on a cell by first detecting and decoding PSS/SSS, then decoding the MIB, and subsequently receiving and decoding SIB1, as well as SIBX. The beam pattern information type 1 is transmitted within SIB1 and/or SIBX. The satellite transmits signals/messages via wide beams during this procedure.

2. UEs within the satellite narrow beam coverage will transmit preamble at the corresponding random access occasion. The preamble is generated by a RA-RNTI for this narrow beam. The satellite receives the preamble via narrow Rx beams.

3. After the satellite has received the preamble from the multiple UEs within the narrow beam coverage, network sends a Msg2 with RA-RNTI to those UEs. The satellite transmits msg2 via wide beams.

4. UEs will send Msg3 to satellite. The satellite receives the Msg3 via narrow Rx beams.

5. The satellite will send Msg4 with contention resolution to UEs via wide beams.

Alternative#2: method 2 of initial access

This method is for the case of UEs with GNSS capability. The method 2 is a 2-step initial access, as is shown in Figure 2. The 1^st step includes preamble#1 and msg2a and is performed via the wide Tx/Rx beam of the satellite. The 2^nd step includes preamble#2, msg2b, msg3 and msg4 and is performed via the wide Tx beam and narrow Rx beam of the satellite.

1. UEs attempt to camp on a cell by first detecting and decoding PSS/SSS, then decoding the MIB, and subsequently receiving and decoding SIB1, as well as SIBX. The beam pattern information type 1 is transmitted within SIB1 and/or SIBX. The satellite transmits signals/messages via wide beams in this procedure.

2. UEs within the satellite wide beam coverage will transmit preamble#1 at the corresponding random access occasion. The preamble#1 is generated by a RA-RNTI#0 for this wide beam. The satellite receives the preamble#1 via wide Rx beams. No further step 2 and CSI-RS narrow beam sweeping is needed if there is no preamble#1 received by the network, thus reduce the overhead of the network/satellite.

3. After the satellite has received the preamble#1 from the multiple UEs within the wide beam coverage, network sends a Msg2a with RA-RNTI#0 to those UEs to confirm their 1st step succeed. UEs received the Msg2a with RA-RNTI#0 may know their 1st step succeed. The satellite transmits the Msg2a via wide Tx beams.

4. The preamble#2 is generated by the RA-RNTI#1 and the random access occasion is selected based on the narrow beam preamble occasions. The satellite receives the preamble#2 via narrow Rx beams.

5. After the satellite has received the preamble#2 from the multiple UEs at different occasions within the wide beam coverage, it sends a Msg2b with RA-RNTI#1 to those UEs . The satellite transmits the Msg2b via wide Tx beams.

6. UEs will send Msg3 to satellite. The satellite receives the Msg3 via narrow Rx beams.

7. The satellite will send Msg4 with contention resolution to UEs via wide beams.

Alternative#3: method 3 of initial access

This method is for the case of UEs with GNSS capability. The method 3 is a 2-step initial access, as is shown in Figure 3. The 1st step includes preamble#1 and msg2a. The 1st step is performed via the wide Tx/Rx beam of the satellite. The 2nd step includes preamble#2, msg2b, msg3 and msg4. The 2nd step is performed via the wide Tx beam and narrow Rx beam of the satellite.

1. UEs attempt to camp on a cell by first detecting and decoding PSS/SSS, then decoding the MIB, and subsequently receiving and decoding SIB1, as well as SIBX. The satellite transmits signals/messages via wide beams in this procedure.

3. After the satellite has received the preamble#1 from the multiple UEs within the wide beam coverage, network sends a Msg2a with RA-RNTI#0 to those UEs to confirm their 1st step succeed. UEs received the Msg2a with RA-RNTI#0 may know their 1st step succeed. The satellite transmits the Msg2a via wide Tx beams. The Msg2a is with beam pattern information type 2.

4. The preamble#2 is generated by the RA-RNTI#1 and the random access occasion is selected based on the narrow beam preamble occasions. The satellite receives the preamble#2 via narrow Rx beams

Alternative#4: method 4 of initial access

This method is for the case of UEs with GNSS capability. The method 4 is a 2-step initial access, as is shown in Figure 4. The 1^st step includes preamble#1 and msg2a and is performed via the wide Tx/Rx beam of the satellite. The 2^nd step includes preamble#2, msg2b, msg3 and msg4. The preamble#2, msg2b, and msg4 is performed via the wide Tx/Rx beam of the satellite. The msg3 is performed via the narrow Rx beam of the satellite.

4. The preamble#2 is generated by the RA-RNTI#1 and the random access occasion is selected based on the wide beam preamble occasions. The satellite receives the preamble#1 via wide Rx beams.

5. After the satellite has received the preamble#2 from the multiple UEs at different occasions within the wide beam coverage, it sends a Msg2b with RA-RNTI#1 and beam pattern information type 2 to those UEs . The satellite transmits the Msg2b via wide Tx beams.

6. UEs will send Msg3 to satellite according to the narrow beam pattern information. The satellite receives the Msg3 via narrow Rx beams.

Alternative#5: method 5 of initial access

This method is for the case of UEs without GNSS capability. In scenarios where the UE lacks GNSS capabilities, it is unable to ascertain its location and, consequently, cannot determine the appropriate narrow beam of the satellite to pair with. To overcome this challenge, the UE actively measures the CSI-RS conveyed through the various narrow beams of the satellite. Based on these measurements, the UE selects a or the most suitable beam for establishing a connection.

The method 5 initial access is shown in Figure 5. The initial access procedure includes preamble, msg2, msg3 and msg4. It is performed via the wide Tx beam and narrow Rx beam of the satellite.

1. UEs attempt to camp on a cell by first detecting and decoding PSS/SSS, then decoding the MIB, and subsequently receiving and decoding SIB1, as well as SIBX. The beam pattern information is or is not transmitted within SIB1 and/or SIBX. The satellite transmits signals/messages via wide beams in this procedure.

2. The satellite transmits CSI-RS via narrow Tx beams to UEs. UEs measures the narrow beam CSI-RS from satellite and know the channel state information, narrow beam ID information etc.

3. UEs within the satellite narrow beam coverage will transmit preamble at the corresponding random access occasion. The preamble is generated by a RA-RNTI for this narrow beam. The satellite receives the preamble via narrow Rx beams.

4. After the satellite has received the preamble from the multiple UEs within the narrow beam coverage, network sends a Msg2 with RA-RNTI to those UEs. The satellite transmits msg2 via wide beams.

5. UEs will send Msg3 to satellite. The satellite receives the Msg3 via narrow Rx beams.

6. The satellite will send Msg4 with contention resolution to UEs via wide beams.

Note 1: The CSI-RS is transmitted via narrow beams of satellite. Distinct CSI-RS resources (time, frequency, or code domain, or an amalgamation thereof) serve to signify the narrow beam ID information.

Note 2: The UE acquires the satellite's narrow beam ID corresponding to the UE’s location by measuring the RSRP of the CSI-RS and/or by evaluating it against a predefined threshold. For instance, the UE conducts measurements of the CSI-RSs transmitted through various narrow beams from the satellite and records their respective RSRPs. Subsequently, the UE selects the narrow beam that delivers the highest RSRP, or alternatively, any narrow beam whose RSRP surpasses a certain threshold. Once the optimal narrow beam is identified, the UE proceeds to transmit a preamble during the designated random access opportunity associated with that specific narrow beam.

Note 3: the beam pattern information of the satellite is informed by the network to UEs in SIB1 and/or SIBX or in connected mode. For the case of in connected mode, the information is via RRC signalling, MAC CE etc, and the beam pattern information is type 3. For the case of in SIB1 and/or SIBX, the beam pattern information is type 1.

Alternative#6: method 6 of initial access

This method is for the case of UEs without GNSS capability. The method 6 is a 2-step initial access, as is shown in Figure 6. The 1st step includes preamble#1 and CSI-RS and is performed via the narrow Tx beam and wide Rx beam of the satellite. The 2nd step includes preamble#2, msg2, msg3 and msg4 and is performed via the wide Tx beam and narrow Rx beam of the satellite.

1. UEs attempt to camp on a cell by first detecting and decoding PSS/SSS, then decoding the MIB, and subsequently receiving and decoding SIB1, as well as SIBX. The narrow beam pattern information is or is not transmitted within SIB1 and/or SIBX. The satellite transmits signals/messages via wide beams in this procedure.

3. The satellite transmits CSI-RS via narrow Tx beams to UEs if there are any UEs in the wide beam area. UEs within the wide beam coverage measure the narrow beam CSI-RS from satellite and know the 1^st step succeeds.

4. UEs within the satellite narrow beam coverage will transmit preamble#2 at the corresponding random access occasion. The preamble is generated by a RA-RNTI#1 for this narrow beam. The satellite receives the preamble via narrow Rx beams.

5. After the satellite has received the preamble from the multiple UEs within the narrow beam coverage, network sends a Msg2 with RA-RNTI#1 to those UEs. The satellite transmits msg2 via wide beams.

Note : the beam pattern information of the satellite is informed by the network to UEs in SIB1 and/or SIBX or in connected mode. For the case of in connected mode, the information is via RRC signalling, MAC CE etc, and the beam pattern information is type 3. For the case of in SIB1 and/or SIBX, the beam pattern information is type 1.

Alternative#7: method 7 of initial access

This method is for the case of UEs without GNSS capability. This approach adheres to the fundamental processes outlined in methods 5 or 6. Nonetheless, it distinguishes itself by utilizing the CSI-RS to convey narrow beam pattern information type 3. Consequently, there is no need to embed explicit narrow beam pattern details within the signaling or messages. It is noteworthy that the narrow beam pattern information is encapsulated as an index or a bit string, which signifies various attributes such as the sequence of narrow beams, their time durations, and their respective coverage areas or geographical locations. The CSI-RS can be generated by this index or bit string, and/or indicate this index or bit string in time/frequency/code domain. Then the UE can derive the narrow beam pattern information by obtain and/or decoding the CSI-RS.

In another aspect, 3 types of beam pattern information is proposed, which suitable for different use case and/or scenarios of the beams used by the satellites. More specifically, we propose to consider the following alternative:

Alternative#8: 3 types of beam pattern information

Type 1 information: Indicate information for at least one of the followings:

-Narrow beams information within one or more wide beams;

-Narrow beams information within one or more cells;

-Narrow beams information within one or more serving satellite coverage;

-Narrow beams information within one specific geographic area of earth;

-Wide beams information within one or more cells;

-Wide beams information within one or more serving satellite coverages;

-Wide beams information within one specific geographic area of earth;

Type 2 information: Indicate information for at least one of the followings:

-Narrow beams information within current serving wide beam;

Type 3 information: Indicate information for at least one of the followings:

-Aspecific serving Narrow beam information;

The beam pattern information content includes at least one of the followings:

-the service order of the narrow beams

-the service order of the wide beams

-the service time duration of the beams

-the location and/or coverage of the narrow beams

-the location and/or coverage of the wide beams

Note 1: The satellite has wide and narrow beams. The coverage of wide beams is larger, and the areas covered by different wide beams may or may not overlap. The coverage of narrow beams is smaller than that of the wide beams, and the areas covered by different narrow beams may or may not overlap. Different sets of narrow beams are within different wide beams. The coverage of a wide beam is either smaller than or equal to the coverage of the satellite.

Note 2: For example, as is shown in Figure 7, beam pattern information type 1 includes beam pattern information of beam 2, 3, 4, 5 and 6; beam pattern information type 2 includes beam pattern information of beam 2, 3 and 4 of wide beam 1, or beam pattern information of beam 5 and 6 of wide beam 0; beam pattern information type 3 includes beam pattern information of beam 2 only, or any other specific narrow beam.

The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more. ” The word “exemplary” is used herein to mean “serving as an example, instance, or illustration. ” Any aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects. Unless specifically stated otherwise, the term “some” refers to one or more. Combinations such as “at least one of A, B, or C, ” “one or more of A, B, or C, ” “at least one of A, B, and C, ” “one or more of A, B, and C, ” and “A, B, C, or any combination thereof” include any combination of A, B, and/or C, and may include multiples of A, multiples of B, or multiples of C. Specifically, combinations such as “at least one of A, B, or C, ” “one or more of A, B, or C, ” “at least one of A, B, and C, ” “one or more of A, B, and C, ” and “A, B, C, or any combination thereof” may be A only, B only, C only, A and B, A and C, B and C, or A and B and C, where any such combinations may contain one or more member or members of A, B, or C. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. The words “module, ” “mechanism, ” “element, ” “UE, ” and the like may not be a substitute for the word “means. ” As such, no claim element is to be construed as a means plus function unless the element is expressly recited using the phrase “means for. ”

While aspects of the present disclosure have been described in conjunction with the specific embodiments thereof that are proposed as examples, alternatives, modifications, and variations to the examples may be made. Accordingly, embodiments as set forth herein are intended to be illustrative and not limiting. There are changes that may be made without departing from the scope of the claims set forth below.

Claims

A method of NR NTN initial access, the method for initial access of NTN are divided into 7 different methods of initial access including methods 1-7.
The method of claim 1, wherein method 1, method 2, method 3 and method 4 of the initial access method is for the case of UEs with GNSS capability, and the method 5, method 6 and method 7 of the initial access method is for the case of UEs without GNSS capability.
The method of claim 1, wherein the method 1 of initial access is a 1-step initial access and the procedure includes preamble, msg2, msg3 and msg4, it is performed via the wide Tx beam and narrow Rx beam of the satellite.
The method of claim 1, wherein the method 2 of initial access is a 2-step initial access, the 1^st step includes preamble#1 and msg2a and is performed via the wide Tx/Rx beam of the satellite, The 2^nd step includes preamble#2, msg2b, msg3 and msg4 and is performed via the wide Tx beam and narrow Rx beam of the satellite.
The method of claim 1, wherein the method 1 and method 2 of initial access, the beam pattern information type 1 is transmitted within SIB1 and/or SIBX.
The method of claim 1, wherein the method 3 of initial access is a 2-step initial access, the 1st step includes preamble#1 and msg2a, the 1st step is performed via the wide Tx/Rx beam of the satellite, the 2nd step includes preamble#2, msg2b, msg3 and msg4, the 2nd step is performed via the wide Tx beam and narrow Rx beam of the satellite, and the beam pattern information type 2 is transmitted within msg2a.
The method of claim 1, wherein the method 4 of initial access is a 2-step initial access, the 1^st step includes preamble#1 and msg2a and is performed via the wide Tx/Rx beam of the satellite, the 2^nd step includes preamble#2, msg2b, msg3 and msg4, the preamble#2, msg2b, and msg4 is performed via the wide Tx/Rx beam of the satellite, the msg3 is performed via the narrow Rx beam of the satellite, and the beam pattern information type 2 is transmitted within msg2b.
The method of claim 1, wherein the method 5 of initial access procedure includes preamble, msg2, msg3 and msg4, it is performed via the wide Tx beam and narrow Rx beam of the satellite.
The method of claim 1, wherein the method 6 of initial access is a 2-step initial access, the 1st step includes preamble#1 and CSI-RS and is performed via the narrow Tx beam and wide Rx beam of the satellite, the 2nd step includes preamble#2, msg2, msg3 and msg4 and is performed via the wide Tx beam and narrow Rx beam of the satellite.
The method of claim 1, wherein the method 7 of initial access adheres to the fundamental processes outlined in methods 5 or 6 and utilizes the CSI-RS to convey beam pattern information type 3.
The method of claim 10, wherein the narrow beam pattern information is encapsulated as an index or a bit string, which signifies various attributes such as the sequence of narrow beams, their time durations, and their respective coverage areas or geographical locations.
The method of claim 10, wherein the CSI-RS can be generated by this index or bit string, and/or indicate this index or bit string in time/frequency/code domain.
The method of claim 8, 9 or 10, wherein the distinct CSI-RS resources (time, frequency, or code domain, or an amalgamation thereof) serve to signify the narrow beam ID information.
The method of claim 8 or 9, wherein the beam pattern information type 1 is informed by the network to UEs in SIB1 and/or SIBX, the beam pattern information type 3 is informed by the network to UEs in connected mode, e.g., via RRC signalling, MAC CE etc.
The method of claim 8, 9 or 10, wherein the CSI-RS is transmitted via narrow beams of satellite.
The method of claim 8, 9 or 10, wherein the UE acquires the satellite's narrow beam ID corresponding to the UE’s location by measuring the RSRP of the CSI-RS and/or by evaluating it against a predefined threshold.
The method of claim 1, wherein the method 2, 3, 4 or 6, no further step 2 and/or CSI-RS narrow beam sweeping is needed if there is no preamble#1 received by the network.
The method of claim 1, wherein the method 5 and 6 of initial access, for the case of beam pattern information is informed by network to UEs in connected mode, the information is via RRC signalling, MAC CE etc, and the beam pattern information is type 3, for the case of beam pattern information via SIB1 and/or SIBX, the beam pattern information is type 1.
The method of claim 1, wherein the 3 types of beam pattern information:

type 1 information: Indicate information for at least one of the followings:

-narrow beams information within one or more wide beams;

-narrow beams information within one or more cells;

-narrow beams information within one or more serving satellite coverage;

-narrow beams information within one specific geographic area of earth;

-wide beams information within one or more cells;

-wide beams information within one or more serving satellite coverages;

-wide beams information within one specific geographic area of earth;

type 2 information: Indicate information for at least one of the followings:

-narrow beams information within current serving wide beam;

type 3 information: Indicate information for at least one of the followings:

-a specific serving Narrow beam information.
The method of claim 18, wherein the beam pattern information content includes at least one of the followings:

-the service order of the narrow beams;

-the service order of the wide beams;

-the service time duration of the beams;

-the location and/or coverage of the narrow beams;

-the location and/or coverage of the wide beams.