CN111556480B

CN111556480B - Method and system for sharing distributed network element by multiple operators

Info

Publication number: CN111556480B
Application number: CN202010078459.9A
Authority: CN
Inventors: 王俊; 刘斌
Original assignee: Individual
Current assignee: Individual
Priority date: 2019-01-31
Filing date: 2020-02-03
Publication date: 2024-03-01
Anticipated expiration: 2040-02-03
Also published as: CN111556480A

Abstract

The invention provides a method and a system for sharing a distributed network element by a plurality of operators, wherein each operator in the operators is configured with a corresponding centralized network element, and UE is connected to a core network through the distributed network element and the centralized network element, and the method comprises the following steps: broadcasting, by the distributed network element, a list of PLMN IDs for the plurality of operators; and determining, by the distributed network element, a PLMN selected by the UE, and connecting the UE to a centralized network element corresponding to an operator of the PLMN selected by the UE. The invention provides high-speed and high-capacity service for the UE with less investment, and can realize the airplane communication of seamless switching between the ground and the airplane.

Description

Method and system for sharing distributed network element by multiple operators

Technical Field

The present invention relates to the field of wireless communications technologies, and in particular, to a method and system for sharing a distributed network element by multiple operators.

Background

Currently, there are two main implementations of aircraft communications: the satellite with Ka/Ku frequency band is switched through the airborne communication equipment and then connected to a ground communication network; or the ground ATG base station is connected through the airborne communication equipment, and the ground-air data transmission is realized by using the 3G or 4G technology. The common problems of both of these approaches are high cost, low access data rate, and high latency.

Disclosure of Invention

In response to the problems with the prior art, in accordance with one embodiment of the present invention, a method is provided for sharing a distributed network element by multiple operators. Wherein each of the plurality of operators is configured with a corresponding centralized network element through which the UE is connected to the core network, the method comprising: broadcasting, by the distributed network element, a list of PLMN IDs for the plurality of operators; and determining, by the distributed network element, a PLMN selected by the UE and connecting the UE to a centralized network element corresponding to an operator of the PLMN selected by the UE.

In the above method, determining, by the distributed network element, a PLMN selected by the UE, and connecting the UE to a centralized network element corresponding to an operator of the PLMN selected by the UE may include: acquiring, by the distributed network element, information of the PLMN selected by the UE from an RRC setup request message or a random access message from the UE, thereby determining an operator selected by the UE; and transmitting, by the distributed network element, an initial UL RRC message transmission message to a centralized network element corresponding to the operator selected by the UE.

In the above method, the information of the PLMN may be a PLMN ID or an index of the PLMN ID in the PLMN ID list.

The method may further include broadcasting, by the distributed network element, a PRACH partition configuration corresponding to the PLMN. Wherein determining, by the distributed network element, a PLMN selected by a UE, and connecting the UE to an operator-corresponding centralized network element of the PLMN selected by the UE may comprise: and determining the PLMN selected by the UE according to the PRACH partition of the random access message sent by the UE by the distributed network unit, thereby determining the operator selected by the UE, and sending an initial UL RRC message transmission message to a centralized network unit corresponding to the operator selected by the UE by the distributed network unit.

In the above method, determining, by the distributed network element, a PLMN selected by the UE, and connecting the UE to a centralized network element corresponding to an operator of the PLMN selected by the UE may include: acquiring, by the distributed network element, information of the PLMN selected by the UE from an RRC setup complete message from the UE, thereby determining an operator selected by the UE; transmitting, by the distributed network element, an initial UL RRC message transmission message to a target centralized network element, wherein the target centralized network element is a centralized network element corresponding to an operator selected by the UE; transmitting, by the target centralized network element, a DL RRC message transmission message and an SRB1 configuration to the distributed network element; transmitting, by the distributed network element, a UE context release message to a source centralized network element with which a connection is established in an RRC establishment phase; and correcting, by the distributed network element, the SRB1 configuration in an RRC reconfiguration message.

The method may further include: and when the RRC establishment request message from the UE is received, searching a centralized network unit corresponding to the operator of the PLMN selected by the UE by the distributed network unit, and rejecting the RRC establishment request of the UE and not broadcasting the PLMN ID of the operator any more if the centralized network unit is not found.

The method may further include: when all UE connected to a centralized network unit corresponding to an operator disconnect from the distributed network unit, starting a timer by the distributed network unit; after the timer expires, the connection of the centralized network element corresponding to the operator is disconnected by the distributed network element.

In the above method, the distributed network element may be a DU or an IAB node of a 5G base station; and the centralized network element may be a CU of 5G base station or a home IAB base station.

In the above method, the distributed network element is connected with the centralized network element through an F1 interface.

In the above method, the UE is located on an aircraft, the distributed network element is deployed on the aircraft, and the centralized network element is deployed on the ground.

There is also provided, in accordance with an embodiment of the present invention, a system for sharing a distributed network element by a plurality of operators, including: a distributed network unit, configured to broadcast PLMN ID lists of the multiple operators, determine a PLMN selected by a UE, and connect the UE to a centralized network unit corresponding to the operator of the PLMN selected by the UE, so that the UE is connected to a core network through the distributed network unit and the centralized network unit; and a centralized network element corresponding to each of the plurality of operators.

The embodiment of the invention provides the following beneficial effects:

the method provides high-speed and high-capacity service for the UE with less investment, and realizes the airplane communication of seamless switching between the ground and the airplane. In addition to aircraft communications, the present invention is also applicable to user communications in other vehicles (e.g., ordinary trains, motor cars, high-speed rails, etc.) as well as in non-moving spaces (e.g., buildings, etc.). In other words, the present invention is applicable to the network architecture of any non-integrated base station (i.e., RAN between CU and a plurality of DUs).

Drawings

The exemplary embodiments will be described in detail by reference to the drawings, which are intended to depict the exemplary embodiments and should not be interpreted as limiting the intended scope of the claims. The drawings are not considered to be drawn to scale unless specifically indicated.

Fig. 1 schematically shows a block diagram of a 5G distributed RAN architecture according to an embodiment of the present invention;

FIG. 2 schematically illustrates a block diagram of a system for sharing DUs by an operator-specific CU for enabling aircraft communications, according to one embodiment of the invention;

FIG. 3 schematically illustrates a schematic diagram of a system for sharing DUs by an operator-specific CU for enabling aircraft communications, according to one embodiment of the invention;

fig. 4 schematically illustrates a flow diagram of a UE initial access procedure in a 5G distributed RAN architecture according to an embodiment of the present invention;

fig. 5 schematically shows a flow chart of a method of sharing a distributed network element by a plurality of operators according to one embodiment of the invention;

FIG. 6 schematically illustrates a block diagram of an IAB architecture according to one embodiment of the invention;

fig. 7 schematically illustrates a schematic diagram of a system for sharing IAB nodes by an operator-specific DgNB for enabling aircraft communications, according to one embodiment of the invention.

Detailed Description

For the purpose of making the technical solutions and advantages of the present invention more apparent, the present invention will be further described in detail by way of specific embodiments with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.

Similar to aircraft communications, there are subway communications, where antennas or remote radio units (Remote Radio Unit, RRU) are pre-installed in subways and buildings, and operators (MNOs, such as chinese communication, chinese mobile, chinese telecommunication, etc.) use these antennas or RRU by paying the owners of subways or buildings. By sharing these antennas or RRUs by all operators' base stations, a seamless access service is provided to user terminals (UEs) within a subway or building. The antenna or RRU is usually connected to the base station of the operator through an optical fiber, and the optical fiber has the characteristics of large capacity, high speed, and the like, so that the communication quality is higher. On this basis, it is possible to consider that the scheme of operators sharing network elements is applied to aircraft communication to achieve seamless handover of aircraft communication. However, the above-mentioned scheme in which operators share antennas/RRUs of subways/buildings cannot be directly applied to aircraft communications, which generally requires connection to be established through an air interface, and if the capacity is too small, there may be a problem in that the antennas or RRUs cannot be directly connected, thereby affecting the aircraft communications.

To enable aircraft communications, a distributed network element may be deployed on the aircraft and operators 'respective centralized network elements deployed on the ground, the distributed network element on the aircraft being shared by multiple centralized network elements on the ground (in other words, the distributed network element on the aircraft being shared by multiple operators), UEs on the aircraft being connected to the core network through the distributed network elements and the operators' centralized network elements, thereby enabling seamless handover of aircraft communications between the ground and the aircraft. Wherein the distributed network element broadcasts an identification list (hereinafter abbreviated PLMN ID list) of public land mobile networks (Public Land Mobile Network, abbreviated PLMNs) of all operators supported by the distributed network element to UEs on the aircraft; the UE selects a PLMN from the received PLMN ID list and communicates information of the selected PLMN to the distributed network element so that the distributed network element can thereby determine the PLMN selected by the UE, i.e. determine the operator of the PLMN; the distributed network element may then connect the UE to the operator specific (corresponding) centralized network element, thereby connecting to the core network for aircraft communication.

According to one embodiment of the present invention, a method of sharing a distributed network element by a plurality of operators is provided. With reference to the 5G Distributed RAN architecture shown in fig. 1, a Distributed Unit (referred to as DU in fig. 1 for short) of a 5G base station is used as a Distributed network Unit deployed on an aircraft, a centralized Unit (referred to as CU in fig. 1 for short) of a 5G base station is used as a centralized network Unit deployed on the ground, a specific CU is configured for each operator, and an F1 interface (referred to as 3gpp TS 38.473) is used for connection between the DU and the CU. Fig. 2-3 schematically show a deployed system in which user plane functions (User Plane Function, briefly UPF) connected to the internet and operator service networks can be integrated to a CU and network slicing functions (see 3gpp TS 23.501) are mainly provided by the CU and the core network.

In summary, the method of sharing a distributed network element by multiple operators of the present embodiment includes: the DU broadcasts a list of PLMN IDs for all operators it supports, determines the PLMN selected by the UE, and connects the UE to the operator's corresponding CU for that PLMN. For the 5G distributed RAN architecture, section 8.1 of 3gpp TS 38.401 defines an initial access procedure of a UE, i.e. a procedure of establishing an RRC connection with a 5G base station (gNB) by the UE in an rrc_idle state, and fig. 4 schematically shows an overall initial access procedure of the UE, wherein the UE establishes a connection with a DU (see gNB-DU in fig. 4) first and then with a CU (see gNB-CU in fig. 4). Based on the initial access procedure shown in fig. 4, to enable sharing of DUs by multiple operators and thus aircraft communication, it is necessary for the DUs to determine the PLMN selected by the UE, i.e. the CU to be connected, before sending an initial UL RRC message transmission (see step 2 in fig. 4, 2.INITIAL UL RRC MESSAGE TRANSFER) message to the CU. In view of this, referring to fig. 5, the method of sharing a distributed network element by a plurality of operators of the present embodiment may include the steps of:

step s11.DU broadcasts system information, wherein the system information comprises a list of PLMN IDs of operators supported by the DU.

Specifically, system information is broadcast to UEs onboard an aircraft by DUs deployed onboard the aircraft. The system information is used to provide the primary information on the radio side, including a small amount of NAS and core network information (e.g., without limitation, system bandwidth, configuration of physical channels and system frame number, cell access and reselection related information, etc.) to facilitate the UE to establish a radio connection and use the various functions provided by the network. In addition, the system information includes a PLMN ID list of operators supported by the DU, which is formed by sequentially arranging PLMN IDs of all operators supported by the DU.

Step s12. The ue selects a PLMN from the received PLMN ID list, adds information of the selected PLMN to an RRC setup request (see 1.RRC Setup Request in fig. 4) message and transmits the RRC setup request message to the DU.

As can be seen from step S12, this embodiment needs to be further modified based on the 3GPP standard, i.e. the information of the PLMN selected by the UE is added in the RRC establishment request message. In addition, referring to fig. 4, the UE may initiate a random Access procedure before transmitting the RRC establishment request message, wherein resources for transmitting the RRC establishment request message may be allocated to the UE in a random Access Response (see b.random Access Response in fig. 4) message. Generally, few resources are allocated to the RRC setup request message and there is no extra number of bits to send more information (e.g., information of the PLMN selected by the UE). In this regard, the DU may be configured to allocate more resources for the UE in the random access response message to enable the UE to transmit a larger RRC setup request message with information of the PLMN selected by the UE.

In one embodiment of the present invention, the information of the PLMN added to the RRC setup request message may be a PLMN ID of the PLMN selected by the UE.

In a preferred embodiment of the present invention, in order to save the number of bits of Uplink (UL) transmission, the information of the PLMN added to the RRC setup request message may be an index of the PLMN ID selected by the UE in the PLMN ID list. For example, if the PLMN ID selected by the UE is the first PLMN ID in the PLMN ID list broadcast by the DU, the information of the PLMN added to the RRC setup request message may be 1; if the PLMN ID selected by the UE is the second PLMN ID in the PLMN ID list, the information of the PLMN added to the RRC setup request message may be 2; and so on.

Step S13.DU obtains the information of the PLMN selected by the UE from the RRC establishment request message from the UE, determines the operator of the PLMN selected by the UE, and sends an initial UL RRC message transmission (see 2.INITIAL UL RRC MESSAGE TRANSFER in FIG. 4) message to the CU corresponding to the operator selected by the UE through the F1 interface so as to complete the access process of the UE.

In the above embodiment, the 5G distributed RAN architecture is utilized to save deployment costs; sharing DUs by multiple carrier-specific CUs to enable aircraft communications so that users on the aircraft can seamlessly enjoy 5G services; the F1 interface is used between the DU and CU to provide high-rate, high-capacity communication services for users onboard the aircraft. In addition to aircraft communications, the method of sharing distributed network elements by multiple operators in the above embodiments is also applicable to communications for users in other vehicles as well as communications for users in non-moving spaces. Furthermore, the F1 interface between the DU and CU may be carried over various links, such as over a wired link, to enable high-rate, high-capacity data transmission.

The above-described embodiments are for delivering information of a PLMN selected by a UE through an RRC setup request message. Referring to fig. 4, information of the PLMN selected by the UE may also be transferred during the UE random access procedure before the DU sends an initial UL RRC message transmission (see step 2 in fig. 4) message to the CU. Based on this, there is also provided, according to an embodiment of the present invention, a method of sharing a distributed network element by a plurality of operators, the method being applicable to a random access procedure defined in 3GPP release 15, namely a 4-step RACH, the method comprising the steps of:

step s21.DU broadcasts system information, wherein the system information comprises a list of PLMN IDs of operators supported by the DU. The system information is further extended, i.e. PLMN specific physical random access channel (Physical Random Access Channel, abbreviated PRACH) resources are defined in the system information. For example, PLMN 1 is assigned PRACH partition 1 (PRACH 1), PLMN 2 is assigned PRACH partition 2 (PRACH 2), and so on.

Step s22. The ue selects a PLMN from the received PLMN ID list and conveys information of its selected PLMN to the DU through Random Access (see a.prach in fig. 4).

Specifically, the UE acquires PRACH configuration corresponding to the selected PLMN from the system information, that is, acquires a specific PRACH partition allocated to the selected PLMN; the UE then transmits a random access message via this particular PRACH partition, whereby the DU may determine the PLMN selected by the UE from the PRACH partition in which the UE transmitted the random access message. For example, if the UE selects PLMN 1, the random access message may be transmitted via PRACH partition PRACH 1 allocated to PLMN 1; if the UE selects PLMN 2, a random access message may be sent via PRACH partition PRACH 2 allocated to PLMN 2 as follows:

PLMN 1: PRACH 1 (preamble group 1, time/frequency resource 1.)

PLMN 2: PRACH 2 (preamble group 2, time/frequency resource 2.)

PLMN 3: PRACH 3 (preamble group 3, time/frequency resource 3.)

……

Step S23.DU obtains information of PLMN selected by UE according to random access of UE, thereby determining operator of PLMN selected by UE.

Wherein, as described above, the DU may determine the PLMN corresponding to the PRACH partition according to the PRACH partition in which the UE sends the Random Access message (see a.prach in fig. 4), that is, obtain the PLMN selected by the UE.

The DU returns a random Access Response (b.random Access Response) message to the UE after receiving the random Access message from the UE. Subsequently, an RRC setup request message is sent by the UE to the DU (see step 1 in fig. 4).

Step S24, after receiving the RRC establishment request message from the UE, the DU sends an initial UL RRC message transmission (see 2.INITIAL UL RRC MESSAGE TRANSFER in FIG. 4) message to the CU corresponding to the operator selected by the UE through the F1 interface so as to complete the access process of the UE.

According to an embodiment of the present invention, there is also provided a method of sharing a distributed network element by a plurality of operators, the method being applicable to a random access procedure defined in 3GPP release 16, i.e. a two-step RACH, the method comprising the steps of:

step s31.DU broadcasts system information, wherein the system information comprises a list of PLMN IDs of operators supported by the DU.

Step S32. The UE selects PLMN from the received PLMN ID list, adds the information of its selected PLMN directly to a Random Access (see A.PRACH) message in FIG. 4, and sends the Random Access message to the DU.

Wherein the information of the PLMN added to the random access message may be a PLMN ID or may be an index of the selected PLMN ID in a PLMN ID list.

Step s33.Du acquires information of the PLMN selected by the UE from the random access message from the UE, thereby determining an operator of the PLMN selected by the UE.

After receiving the random access message from the UE, the DU returns a random access response message to the UE; subsequently, an RRC setup request message is sent by the UE to the DU.

Step S34, after receiving the RRC establishment request message from the UE, the DU sends an initial UL RRC message transmission (see 2.INITIAL UL RRC MESSAGE TRANSFER in FIG. 4) message to the CU corresponding to the operator selected by the UE through the F1 interface so as to complete the access process of the UE.

The several embodiments described above all need to be modified on the basis of the 3GPP standard and system information needs to be extended, even if the version after 3GPP release 16 accepts the solution described in the above embodiments, the situation that the UE does not support PRACH partition needs to be considered. For UEs that do not support PRACH partitioning, according to one embodiment of the invention, there is also provided a method of sharing a distributed network element by multiple operators. Wherein, after the UE sends an RRC setup complete (see 5.RRC Setup Complete in fig. 4) message to the DU, the DU redirects the UE to the CU corresponding to the operator of the PLMN selected by the UE. It should be noted that, the current 3GPP standard already adopts the UE redirection procedure, and the method for sharing the distributed network element by multiple operators includes the following steps:

step s41.DU broadcasts system information, wherein the system information comprises a list of PLMN IDs of operators supported by the DU.

Step s42. The ue selects a PLMN from the received PLMN ID list, adds information of the selected PLMN to an RRC setup complete (see 5.RRC Setup Complete in fig. 4) message, and transmits the RRC setup complete message to the DU. The information of the PLMN added to the RRC setup complete message may be a PLMN ID, or may be an index of the selected PLMN ID in a PLMN ID list.

Wherein the UE may select a PLMN from the PLMN ID list, i.e. select an operator, based on rules defined in GPP TS 23.122; information of the selected PLMN is then added to the RRC setup complete message and the RRC setup complete message is sent to the DU. It should be appreciated that before sending the RRC setup complete message, the DU has directed the UE to one CU (referred to as the source CU, see steps 1-4 in fig. 4).

Step S43.DU obtains the information of PLMN selected by UE from RRC setup completion message from UE, determines the operator of PLMN selected by UE, redirects UE to CU corresponding to the operator selected by UE through F1 interface. In one embodiment, step S43 comprises the following sub-steps:

in a substep s431.Du, the information of the PLMN selected by the UE is obtained from the RRC setup complete message from the UE, so as to determine the operator of the PLMN selected by the UE, and an INITIAL UL RRC message transmission (INITIAL UL RRC MESSAGE TRANSFER) message is sent to the CU corresponding to the operator selected by the UE through the F1 interface, which is also called a target CU. Wherein the initial UL RRC message transmission message includes a lower layer configuration of the UE.

Sub-step s432. DL RRC messaging (DL RRC MESSAGE TRANSFER) messages are sent by the target CU to the DU over the F1 interface. Wherein the DL RRC message transfer message sends the lower layer configuration back to the DU, and the target CU also sends its SRB1 configuration to the DU.

The SRB1 configuration for different operators should generally be the same, but with the difference that the time reordering timer is set, which is only valid if the RLC layer cannot correct transmission failures in time. In case of different SRB1 configurations of different operators, the UE should still use the old SRB1 configuration received in the RRC Setup (see 4.RRC Setup in fig. 4) message for a short time. Subsequently, the DU may correct the SRB1 configuration in an RRC reconfiguration (see 15.RRC Reconfiguration in fig. 4) message, where the operator-specific CUs sharing the DU should retransmit its SRB1 configuration.

Substep s433 a UE context release (UE Context Release) message is sent by the DU to the source CU over the F1 interface to release the source CU.

The above-described embodiment uses DUs of 5G base stations as distributed network units deployed on board an aircraft, and CUs of 5G base stations as centralized network units deployed on the ground. In other cases, a distributed network element other than a DU may also be used, as well as a centralized network element other than a CU. Based on this, according to one embodiment of the invention, there is also provided a method of sharing a distributed network element by a plurality of operators. Therein, an integrated access and backhaul (Integrated Access and Backhaul, abbreviated IAB) architecture as shown in fig. 6 is utilized (see 3gpp TR 38.874), using an IAB node as a distributed network element on board an aircraft, and a home IAB base station (IAB Donor, dgNB in fig. 7) as a centralized network element on the ground, wherein the IAB node comprises a DU and a user Terminal (MT), and the home IAB base station (DgNB) comprises a DU and a CU. A specific home IAB base station (DgNB) is configured for each operator and an F1 interface is employed between DUs in the IAB node and CUs of the home IAB base station (DgNB), which F1 interface may be carried over the 5G air interface. Fig. 7 schematically illustrates a deployed system, since 3GPP release 16 has defined the protocols, functions and flows of the interfaces in the IAB architecture (where it is specified how the F1 interface is carried over the 5G air interface), providing better coordination and QoS support between the UE air interface and the forward air interface than the embodiment above with DUs as distributed network elements and CUs as centralized network elements.

The steps of a method of sharing a distributed network element (IAB node) by a plurality of operators are described below with reference to fig. 7:

the IAB node broadcasts system information including a list of PLMN IDs of operators supported by the IAB node in step s51.

In particular, an IAB node deployed on an aircraft may have a unit (not shown in fig. 7) shared by multiple operators that broadcasts system information to UEs on the aircraft, including a list of PLMN IDs for operators supported by the IAB node.

Step S52.IAB node establishes connection with DgNB corresponding to the operator selected by UE dynamically according to the information of PLMN selected by UE, namely, establishes connection between DU in IAB node and CU in the selected DgNB.

The procedure of selecting a PLMN by the UE may be referred to above, and will not be described herein. In one embodiment of the present invention, step S52 may include:

upon receiving the RRC setup request (RRC Setup Request) message from the UE, the IAB node will attempt to establish a connection with the operator-specific DgNB if it has not already established a connection with the DgNB corresponding to the operator selected by the UE. Wherein the IAB node looks up the DgNB corresponding to the appropriate operator, if found, establishes a connection, if not found, the IAB node will reject the RRC setup request of the UE and remove the PLMN ID of that operator from the system information it broadcasts (i.e. the PLMN ID of that operator is no longer broadcast).

Step S53. When all the UEs connected to the DgNB corresponding to a certain operator are disconnected from the IAB node, the IAB node will keep the connection with the DgNB for the UE of the operator for a certain time, and then disconnect the connection with the DgNB.

Specifically, when all UEs connected to a DgNB corresponding to a certain operator disconnect from the IAB node, the IAB node starts a timer; after the timer expires, the IAB node disconnects the DgNB corresponding to the operator.

In the above embodiment, the IAB node deployed on the aircraft has one unit shared by a plurality of operators. However, those skilled in the art will appreciate that in other embodiments, an IAB node deployed on an aircraft may have multiple operator-specific units, each supporting only its corresponding operator.

It should be noted that some example methods are described as a flow of steps, although the flow represents operations as being performed sequentially, it will be appreciated that many of the operations may be performed in parallel, concurrently, or synchronously. In addition, the order of operations may be rearranged. The process may terminate when the operation is completed, but may also have additional steps not included in the figures or embodiments.

The above-described methods may be implemented in hardware, software, firmware, middleware, pseudocode, hardware description language, or any combination thereof. When implemented in software, firmware, middleware or pseudocode, the program code or code segments to perform the tasks can be stored in a computer readable medium such as a storage medium and the processor can perform the tasks.

It should be appreciated that the exemplary embodiments implemented in software are typically encoded on some form of program storage medium or implemented over some type of transmission medium. The program storage medium may be any non-transitory storage medium, such as a magnetic disk (e.g., a floppy disk or a hard disk) or an optical disk (e.g., a compact disk read only memory or "CD ROM"), and may be read-only or random access. Similarly, the transmission medium may be twisted wire pairs, coaxial cable, optical fiber, or some other suitable transmission medium known to the art.

While the invention has been described in terms of preferred embodiments, the invention is not limited to the embodiments described herein, but encompasses various changes and modifications that may be made without departing from the scope of the invention.

Claims

1. A method of sharing a distributed network element by a plurality of operators, wherein each of the plurality of operators is configured with a corresponding centralized network element through which UEs connect to a core network, the method comprising:

broadcasting, by the distributed network element, a list of PLMNIDs for the plurality of operators;

acquiring, by the distributed network element, information of the PLMN selected by the UE from an RRC setup request message or a random access message from the UE, thereby determining an operator selected by the UE; and

and transmitting an initial UL RRC message transmission message to a centralized network element corresponding to the operator selected by the UE by the distributed network element.

2. The method of claim 1, wherein the information of the PLMN is a PLMN ID or an index of a PLMNID in the PLMNID list.

3. The method of any of claims 1-2, wherein the method further comprises:

and when the RRC establishment request message from the UE is received, searching a centralized network unit corresponding to the operator of the PLMN selected by the UE by the distributed network unit, and rejecting the RRC establishment request of the UE and not broadcasting the PLMNID of the operator if the centralized network unit is not found.

4. The method of any of claims 1-2, wherein the method further comprises:

when all UE connected to a centralized network unit corresponding to an operator disconnect from the distributed network unit, starting a timer by the distributed network unit;

after the timer expires, the connection of the centralized network element corresponding to the operator is disconnected by the distributed network element.

5. The method according to any of claims 1-2, wherein the distributed network unit is a DU or an IAB node of a 5G base station; the centralized network element is a CU of 5G base station or a home IAB base station.

6. The method of any of claims 1-2, wherein the distributed network element and the centralized network element are connected by an F1 interface.

7. The method of any of claims 1-2, wherein the UE is located on an aircraft, the distributed network element is deployed on an aircraft, and the centralized network element is deployed on the ground.

8. A method of sharing a distributed network element by a plurality of operators, wherein each of the plurality of operators is configured with a corresponding centralized network element through which UEs connect to a core network, the method comprising:

broadcasting, by the distributed network element, a PLMN ID list of the plurality of operators and PRACH partition configuration corresponding to the PLMN;

determining, by the distributed network element, a PLMN selected by the UE based on a PRACH partition from which the UE transmits random access messages, thereby determining an operator selected by the UE,

9. The method of claim 8, wherein the method further comprises:

10. The method of claim 8, wherein the method further comprises:

11. The method of claim 8, wherein the distributed network element is a DU or an IAB node of a 5G base station; the centralized network element is a CU of 5G base station or a home IAB base station.

12. The method of claim 8, wherein the distributed network element and the centralized network element are connected by an F1 interface.

13. The method of claim 8, wherein the UE is located on an aircraft, the distributed network element is deployed on the aircraft, and the centralized network element is deployed on the ground.

14. A method of sharing a distributed network element by a plurality of operators, wherein each of the plurality of operators is configured with a corresponding centralized network element through which UEs connect to a core network, the method comprising:

acquiring, by the distributed network element, information of the PLMN selected by the UE from an RRC setup complete message from the UE, thereby determining an operator selected by the UE;

transmitting, by the distributed network element, an initial UL RRC message transmission message to a target centralized network element, wherein the target centralized network element is a centralized network element corresponding to an operator selected by the UE;

transmitting, by the target centralized network element, a DL RRC message transmission message and an SRB1 configuration to the distributed network element;

transmitting, by the distributed network element, a UE context release message to a source centralized network element with which a connection is established in an RRC establishment phase; and

correcting the SRB1 configuration in an RRC reconfiguration message by the distributed network element.

15. The method of claim 14, wherein the method further comprises:

16. The method of claim 14, wherein the method further comprises:

17. The method of claim 14, wherein the distributed network element is a DU or an IAB node of a 5G base station; the centralized network element is a CU of 5G base station or a home IAB base station.

18. The method of claim 14, wherein the distributed network element and the centralized network element are connected by an F1 interface.

19. The method of claim 14, wherein the UE is located on an aircraft, the distributed network element is deployed on the aircraft, and the centralized network element is deployed on the ground.

20. A system for sharing a distributed network element by a plurality of operators, wherein the system comprises:

a distributed network element for broadcasting PLMN ID lists of the plurality of operators, determining a PLMN selected by a UE in the method of any one of claims 1-19, and connecting the UE to a centralized network element corresponding to the operator of the PLMN selected by the UE, such that the UE is connected to a core network through the distributed network element and the centralized network element; and

a centralized network element corresponding to each of the plurality of operators.