CN110740485A

CN110740485A - Node selection method and device for integrated access and backhaul system

Info

Publication number: CN110740485A
Application number: CN201910945059.0A
Authority: CN
Inventors: 刘莺迎; 王益伟; 龙娇妍; 池程
Original assignee: Henan University of Animal Husbandry and Economy
Current assignee: Henan University of Animal Husbandry and Economy
Priority date: 2019-09-30
Filing date: 2019-09-30
Publication date: 2020-01-31

Abstract

The present invention relates to node selection methods for integrated access and backhaul systems deployed in new wireless NRs using massive multiple input multiple output MIMO systems including multiple IAB nodes, of which is partially donor IAB nodes, control signaling required to enhance LTE RRC signaling to support IAB node integration processes to dynamically switch backhaul links, IAB nodes supporting multiplexing of access links and backhaul links in TDM, FDM, and SDM with half-duplex constraints, the selection methods including that when an IAB node performs cell selection/reselection, an IAB node with a smaller number of hops back to the IAB should have higher priority and the load of the IAB node should be lower, so that NR cells can be deployed flexibly, very densely, and connected to the IAB node with fewer backhaul hops can reduce delay and achieve better resource efficiency.

Description

Node selection method and device for integrated access and backhaul system

Technical Field

The present invention relates to wireless communication technology, and more particularly, to link assistance information reporting and data transmission in a wireless communication system.

Background

A wireless communication system may include a base station (hereinafter, referred to as "BS") that communicates with a user equipment (hereinafter, referred to as "UE"). The UE may include a mobile device (e.g., a cellular phone, a tablet, a laptop, an internet of things (IoT) device, etc.). The quality of a communication link or channel between a BS and a UE may deteriorate due to various factors, such as blockage of buildings, a relatively long distance between the BS and the UE, and the like. A method of solving this problem may include deploying a relay node (hereinafter referred to as "RN") in a wireless communication system to enhance and/or extend coverage of a BS.

BSs communicating with UEs through RNs are referred to as donor BS. these RNs form backhaul links with the donor BS allowing UEs to reach the donor BS. through RNs and signals from the UE can also be sent directly from RNs to the donor BS. Integrated Access and Backhaul (IAB) systems evolving from RN deployment in 3GPP are under development to support multihop relay in New Radio (NR) communication networks.

However, the backhaul link may fail in some cases, and therefore new solutions are needed to protect data or signal transmission.

Disclosure of Invention

Accordingly, aspects of the present invention provide a method of node selection for an integrated access and backhaul system deployed in a new wireless NR using a massive multiple-input multiple-output MIMO system including a plurality of IAB nodes, of which is a donor IAB node, control signaling required to enhance LTE RRC signaling to support IAB node integration procedures to dynamically switch backhaul links, IAB nodes supporting multiplexing of access links and backhaul links in TDM, FDM and SDM with half-duplex constraints, characterized by:

when the IAB node performs cell selection/reselection, the IAB node with the lower number of hops back to the IAB donor should have a higher priority and the load of the IAB node should be lower.

Further , donor IAB reselection is included, wherein,

step 0: the IAB node is configured by the serving IAB donor 1 to report information, measurements of candidate backhaul links between the IAB node and neighboring IAB donors,

step 1: the IAB node reports the assistance information to the serving donor IAB,

, the source donor IAB decides to handover based on the measurement, the source donor IAB sends a backhaul handover request to the target donor IAB,

and step 3: if resources are available in the target IAB donor, the target IAB donor will reply with an ACK to the source IAB donor,

and 4, step 4: the source IAB donor sends a backhaul handover command to the IAB node,

, upon receiving the backhaul handover command message, the IAB node will connect to the target IAB donor,

step 6: after the IAB node is successfully connected, the target IAB donor transmits the complete backhaul switch to the source IAB donor.

Further , a next hop IAB node reselection is included, wherein,

IAB node1 and IAB node2 are both within the coverage of the IAB donor, but IAB node3 is out of the coverage of the donor IAB, and therefore IAB node3 is connected to the IAB donor relayed by either IAB node1 or IAB node2,

step 0: the serving IAB donor configures the IAB node to report information, measurements, delay or load information,

step 1: the IAB node reports assistance information, measurements of backhaul links related to IAB node2 and IAB node3,

, once the IAB donor decides to perform an IAB node switch, the IAB donor sends a backhaul handover request to the target IAB node2,

and step 3: the target IAB node2 replies an ACK to the IAB donor,

and 4, step 4: the IAB donor sends a backhaul handover command to the IAB node3 relayed by the IAB node1, FFS: the contents of the backhaul handover command are transparent to IAB node1,

and 5: after receiving the backhaul handover command message, the IAB node3 connects to the target IAB node2,

step 6: after successful connection of IAB node3, the target IAB node2 will send the full backhaul switch to the donor IAB,

and 7: the IAB donor communicates the backhaul release to IAB node1,

in step 1, the IAB node will report information to help the serving donor IAB make its decision, the following information will help the donor IAB,

measurement of the link between IAB node3 and the candidate IAB node, or

Delay information of candidate IAB nodes, or

-loading information of candidate IAB nodes;

in case of IAB node reselection, the IAB node should report side information including measurement results, latency information and load information to the donor IAB.

Further , the slot boundaries of the IAB node and the donor IAB node should be aligned with an integer multiple symbol shift.

, IAB node topology management includes two types, centralized topology management and distributed topology management, in the centralized topology management, the topology of the whole IAB network is managed by a centralized entity, the entity maintains the global topology of the IAB network, the centralized entity is located on the donor IAB, the core network or the application server, in the distributed topology management, each IAB node and IAB donor has its own topology management entity, and maintains the local topology according to the information exchange with the adjacent nodes.

In another aspect, the present invention provides a node selection apparatus for integrated access and backhaul system deployed in new wireless NR, using massive MIMO system with multiple inputs and outputs, including multiple IAB nodes, part being donor IAB node, requiring LTE RRC signaling enhancement to support control signaling required for IAB node integration process to dynamically switch backhaul link, and supporting multiplexing of access link and backhaul link in TDM, FDM and SDM with half duplex constraint, comprising:

selection means for, when the IAB node performs cell selection/reselection, the IAB node with a smaller number of hops back to the IAB donor should have a higher priority and the load of the IAB node should be lower.

, further comprising donor IAB reselection means for performing the following steps, wherein,

, further comprising a next hop IAB node reselection means to perform the following steps, wherein,

and step 3: the target IAB node2 replies an ACK to the IAB donor,

and 7: the IAB donor communicates the backhaul release to IAB node1,

measurement of the link between IAB node3 and the candidate IAB node, or

Delay information of candidate IAB nodes, or

-loading information of candidate IAB nodes;

The invention achieves the following beneficial effects:

, which is a potential technology for future cellular network deployment scenarios and applications, is the support of wireless backhaul and relay links, allowing for flexible, very dense deployment of NR cells without scaling down the density of the transport network.

Drawings

The invention is now described in the following with respect to aspects of preferred embodiments thereof, with reference to the accompanying drawings, in which:

fig. 1 illustrates a network system architecture for integrated access and backhaul links;

fig. 2 shows a diagram of semi-static slot format configurations of a donor gbb and an IAB node;

fig. 3 shows a diagram of a dynamic slot format configuration on a group common PDCCH by SFI;

fig. 4 shows a schematic diagram of a multi-hop backhaul for an IAB node.

Detailed Description

Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. In this regard, embodiments of the present invention may take different forms and should not be construed as limited to the description set forth herein. Accordingly, the embodiments are described below by referring to the drawings only to illustrate aspects of the present invention.

In the prior art, due to the larger available bandwidth of NR compared to LTE (e.g. mmWave spectrum) and the local deployment of massive MIMO or multi-beam systems in NR, opportunities are created for developing and deploying integrated access and backhaul links. This may allow for a dense network of self-backhauled NR cells to be more easily deployed in a more integrated manner by basing on many control and data channels/procedures defined to provide access to the UE. An example illustration of a network with such integrated access and backhaul links is shown in fig. 1, where the access and backhaul links can be multiplexed by a relay node (rrtp) in time, frequency or space.

For current network systems that integrate access and backhaul links, a number of factors need to be considered at the physical layer. The operation of the different links may be on the same or different frequencies (also referred to as "in-band" and "out-of-band" relays). Although effective support of out-of-band relays is important for some NR deployment schemes, it is important to know the requirements of in-band operation, which means that interworking with access links running on the same frequency is tighter to accommodate duplex restrictions and avoid/mitigate operation. And (4) interference.

The term lockout overcomes short term blockages in mmWave systems may require RAN-based fast mechanisms that switch between rTRPs, where no core network involvement is required, the above described need to mitigate short term blockages for NR operations in the millimeter wave spectrum, and the desire to more easily deploy self-backhauled NR cells, creating a need to develop an integrated framework that allows fast handover access and backhaul links.

The SA1 has established a service requirement for wireless self-backhauling. The method comprises the following steps:

the 5G network should enable operators to support wireless self-backhauling using NR and E-UTRA.

The 5G network should support flexible and efficient wireless self-backhauling for indoor and outdoor scenarios.

The 5G network should support flexible allocation of radio resources between access and backhaul functions.

The 5G network should support autonomous configuration of access and wireless self-backhauling functions.

The 5G network should support multi-hop wireless self-backhauling.

The 5G network should support autonomous adaptation to the wireless self-backhauling network topology to minimize service disruption.

The 5G network should support topologically redundant connections over the wireless self-backhaul.

After LTE initial access, the IAB node needs to identify itself as an NR IAB node and request LTE-NR dual connectivity.LTE RRC signaling needs to be enhanced to support the control signaling needed for the IAB node integration process, such as routing updates and IAB with F1-DU setup procedures, which are part of the control signaling of NR F1 during initial setup and IAB node control signaling. upon completion of the IAB integration process, the donor gNB will configure the LTE-NR bi-directional connection to the IAB node as an NR cell, as an SCG, for the backhaul link of the IAB node.

The IAB node will perform LTE initial access for NSA operations. LTE RRC signaling needs to be enhanced to support control signaling required for the IAB node integration process, such as route update and IAB DU setup negotiation with F1-AP setup process, and both SSB and CSI-RS can be used for the IAB to detect and measure candidate backhaul links at phase 2 to dynamically switch backhaul links. The radio resources for backhaul link measurements will be configured with respect to the candidate donor gNB. Under half-duplex constraints, the radio resources used by the IAB node to measure the backhaul link should be configured for the UE-specific RS to avoid potential cell-specific radio resource collisions that may synchronize different scenarios of the node according to transmission timing in transmissions to the UE between the donor gNB and the IAB. The radio resources used by the IAB node for candidate backhaul link measurements should be configured coordinated among the candidate donor gnbs to allow simultaneous measurements of multiple backhaul links, including the serving and target donor gnbs. Using SSB in TDM/FDM with/without muting will limit the number of candidate backhaul links to measure. Since the IAB node will be considered as a UE in CONNECTED state, the CSI-RS resource for CSI or RRM measurements should be a good reference signal for backhaul link measurements. The configuration of CSI-RS resources for IAB node backhaul link measurements is similar to UE CSI measurements from multiple beams for beam management or CoMP. The plurality of NZP and ZP CSI-RS resources may be configured as reference for backhaul link measurement for any candidate backhaul link and interference mitigation for non-measured backhaul links, respectively, to allow the IAB node to measure multiple candidate backhaul links simultaneously.

Further , the configuration of the plurality of NZP and ZP CSI-RS resources as a reference for backhaul link measurement for any candidate backhaul link and interference mitigation for non-measured backhaul links may be considered to allow the IAB node to measure multiple candidate backhaul links simultaneously.

By serving the gNB, the CSI-RS resources configured for candidate backhaul link measurements may also be used for RRM measurements in case NZP and ZP CSI-RS resource configurations are coordinated between the candidate backhaul links. The CSI-RS resources used for beam management or CSI measurement of the donor gbb should be reused for RRM measurement and RLM measurement of the IAB backhaul link. An advantage of using CSI-RS for RRM and RLM measurements is that measurement performance may be improved when ZP CSI-RS is configured on the same REs of CSI-RS resources of neighboring cells to mitigate interference. .

The CSI-RS resources configured for beam management or CSI measurement of the donor gbb should be reused for RRM measurement and RLM measurement of the IAB backhaul link.

For example, in a first phase of discovery, the node IAB may be configured to perform a full-duplex operation in the battle of half-duplex constraints, and transmit timing conditions 1-7 studied in the IAB study may not work at all if the network is not fully synchronized (including offset synchronization).

The CSI-RS used as RS for IAB node backhaul link measurements will work with the different case where offset synchronized DL/UL transmission timing is required between the IAB node and the donor gbb.

In RAN1#93, the IAB node supports multiplexing of the access link and the backhaul link in TDM, FDM and SDM with half-duplex constraints for in-band operation of the backhaul link and the IAB Uu access link, when links are in transmit state and the other link is in receive state, transmission sidelobes will cause self-interference.

The interference mitigation scheme is to configure the DL/UL slot format for the IAB node by an RRC semi-statically, as shown in FIG. 1, to avoid simultaneous reception in links and transmission in another link, as shown in FIG. 2, if the DL/UL slot format of the donor gNB is configured by the RRC semi-statically, as shown in FIG. 1, to avoid simultaneous reception in the IAB node and transmission in another link.

If the DL/UL slot format is dynamically configured on the donor gNB and the SFI is indicated on the group common PDCCH, the IAB may assume the role of the UE and decode the group common PDCCH and determine its DL/UL slot format, as shown in FIG. 3, the slot boundary on the IAB node is delayed by symbols after DL transmission from the backhaul link, wherein the access link slot format dynamically adjusts each slot based on the SFI received from the donor gNB from FIGS. 2 and 3, interference mitigation by the IAB may be achieved by semi-statically or dynamically allocating the DL/UL slot configuration on the IAB node based on the DL/UL slot configuration of the donor gNB.

It can be seen from fig. 2 and 3 that the slot boundaries of IAB nodes should be offset by a few symbols relative to the slot boundaries of the donor gNB to avoid self-interference between the access link and the backhaul link while another links are receiving at link transmissions for UL transmissions on the backhaul link, the transmission time will be determined by the TA command from the donor gNB, which TA is derived from the propagation delay for the IAB backhaul link, since the IAB nodes are fixed, the propagation delay should be stable.

Therefore, the slot boundaries of the IAB node and donor gNB should be aligned with the integer multiple symbol shift. The number of OFDM symbols offset at the slot boundary of an IAB node should be configured to be the same for all IAB nodes in the cluster.

Furthermore, based on the current NR specifications, the UE will perform measurements and select a suitable cell based on RRC _ IDLE state measurements and cell selection criteria, which is not optimal due to problems in the physical layer design. While camped on a cell, the UE should periodically search for a better cell according to cell reselection criteria. If a better cell is found, the cell is selected. Likewise, if the IAB node MT part attempts to connect to the parent IAB node, the cell selection and reselection schemes should be the same. But considering that different IAB nodes have different backhaul hop counts to reach the IAB donor, if the IAB node is connected to an IAB node with a smaller hop count than the IAB donor, less radio resources and less end-to-end delay will be required.

As shown in fig. 4, IAB2 requires two hops to reach the donor IAB, while IAB-x only requires hops to reach the donor IAB-assuming IAB2 and IAB-x are both cells suitable for IAB3, and IAB3 chooses to connect to IAB2, the packet transmission delay from a UE served by IAB3 to the IAB donor includes four parts, 1) delay between UE and IAB3, 2) delay between IAB3 and IAB2, 3) delay between IAB2 and IAB1, and 4) delay between IAB1 and the donor IAB in another aspect, if IAB3 is connected to IABx, the packet transmission delay from a UE served by IAB3 to the IAB donor includes only three parts.

How to connect to the IAB node with fewer backhaul hops may reduce latency and achieve better resource efficiency. Is a matter that must be considered.

Based on the above analysis, IAB nodes with a lower number of hops back to the IAB donor should have higher priority when the IAB node performs cell selection/reselection. In addition to the number of hops, links with lower load should also be considered when the IAB node performs cell selection/reselection in order to achieve load balancing.

Therefore, when an IAB node performs cell selection/reselection, the IAB node with a smaller number of backhaul hops should have a higher priority and the load of the IAB node should be lower.

generally, the IAB node does not have to establish a connection with each detected neighboring node, rather, the IAB node only needs to select or a few neighboring cells to connect.

The parent IAB node selection may be based on control of a centralized topology management entity or a distributed topology management entity in order to implement the parent IAB node selection. The following operations should also be realized.

In addition, the IAB node must update measurement reports to the centralized topology management entity in view of changing channel environments and radio links, meaning that each IAB will continue to perform measurements on neighboring cells and report to the centralized entity.

Further , for centralized topology management, the IAB node must perform measurements and send measurement reports to the centralized topology management entity.

Regarding the location of the centralized topology management entity, a donor CU or donor node is considered eligible for centralized topology management. For the case of CU-DU splitting, the donor CU can obtain measurement reports for all access UE and IAB node MT parts, the connection between IAB nodes and the congestion status of the backhaul link. Thus, the donor CU may be a centralized topology management entity. For the non-CU-DU split case, the IAB donor node may obtain topology related information from the IAB node over the Xn interface and then make topology control decisions. However, this means that the Xn interface should be enhanced to topology-dependent information exchange.

It should also be noted that donor CUs or donor nodes may be eligible for centralized topology management.

In distributed topology management, there are topology management entities per IAB node and IAB donor, and a local topology is maintained at each node based on information received from its neighbors.

To assist an IAB node in selecting a suitable parent IAB node, information needed to select/reselect an IAB cell, such as an IAB indication, a donor backhaul hop count to an IAB, and a traffic load status data forwarding path for an intermediate IAB node along the IAB node, may be broadcast by each IAB node .

For distributed topology management, information required for IAB cell selection/reselection may be broadcast at , such as an IAB indication, a donor IAB indication, the number of backhaul hops to an IAB donor, and the traffic load status data forwarding path along the IAB node by intermediate IAB nodes.

Further in step , the method is carried out,

for reselection of the IAB node, the following is also processed:

topology adjustments are made for physically fixed relays to achieve reliable operation, such as mitigating congestion and load variations on the backhaul link the IAB node reselection is processed as follows based on IAB donor reselection and the lower hop IAB node reselection, respectively.

(1) Donor IAB reselection

Step 0: the IAB node is configured by the serving IAB donor 1 to report information, such as measurements of candidate backhaul links between the IAB node and neighboring IAB donors.

Step 1: the IAB node reports assistance information (e.g., measurement results) to the serving donor IAB.

Once the source donor IAB decides to handover based on the measurement, the source donor IAB sends a backhaul handover request to the target donor IAB.

And step 3: if resources are available in the target IAB donor, the target IAB donor will reply an ACK to the source IAB donor.

And 4, step 4: the source IAB donor sends a backhaul handover command to the IAB node.

upon receiving the backhaul handover command message, the IAB node will connect to the target IAB donor.

The above-described CP procedure for donor IAB reselection is similar to the handover procedure.

(2) Down hop IAB node reselection

Assume that IAB node1 and IAB node2 are both within the coverage of the IAB donor. However, IAB node3 is out of coverage of the donor IAB. Thus, IAB node3 is connected to an IAB donor relayed by IAB node1 or IAB node 2.

Step 0: the serving IAB donor configures an IAB node (e.g., IAB node 3) to report information, such as measurement results, delay or load information.

Step 1: the IAB node reports assistance information such as measurements of the backhaul links related to IAB node2 and IAB node 3.

the IAB donor sends a backhaul handover request to the target IAB node2, once the IAB donor decides to perform an IAB node handover.

And step 3: the target IAB node2 replies with an ACK to the IAB donor.

And 4, step 4: the IAB donor sends a backhaul handover command to the IAB node3 relayed by the IAB node 1. FFS: the contents of the backhaul handover command are transparent to IAB node 1.

And 5: after receiving the backhaul handover command message, the IAB node3 connects to the target IAB node 2.

Step 6: after IAB node3 successfully connects, target IAB node2 will send the full backhaul exchange to the donor IAB.

And 7: the IAB donor communicates the backhaul release to IAB node 1.

In step 1, the IAB node will report information to help the donor IAB in service make a decision.

Measurement of the link between IAB node3 and the candidate IAB node

Delay information of candidate IAB nodes (e.g. IAB node1 and IAB node 2)

Loading information of candidate IAB nodes (e.g. IAB node1 and IAB node 2)

The above embodiments are only optional embodiments of the present invention, and are not intended to limit the present invention in any way, and any simple modification, equivalent change, combination or modification made on the above embodiments according to the technical spirit of the present invention still belongs to the protection scope of the technical solution of the present invention.

It will be understood by those skilled in the art that all or part of the steps of the above methods may be implemented by a program instructing associated hardware (e.g., a processor), and the program may be stored in a computer readable storage medium such as a read-only memory, a magnetic or optical disk, etc. alternatively, all or part of the steps of the above embodiments may be implemented by or more integrated circuits.

Although the embodiments disclosed in the present application are described above, the descriptions are only used for facilitating the understanding of the embodiments of the present application, and are not intended to limit the present application, such as the specific implementation methods in the embodiments of the present invention. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the disclosure as defined by the appended claims.

While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

The node selection method of integrated access and backhaul system, the integrated access and backhaul IAB system is deployed in new wireless NR, uses large-scale MIMO system with multiple input multiple output, including multiple IAB nodes, wherein part is donor IAB node, needs to enhance LTE RRC signaling to support control signaling required by IAB node integration process to dynamically switch backhaul link, and the IAB node supports multiplexing access link and backhaul link in TDM, FDM and SDM with half-duplex constraint, characterized in that, it includes:

when the IAB node performs cell selection/reselection, the IAB node with the lower number of hops back to the IAB donor should have a higher priority and the load of the IAB node should be lower.
2. The selection method of claim 1, further comprising donor IAB reselection, wherein,

step 0: the IAB node is configured by the serving IAB donor 1 to report information, measurements of candidate backhaul links between the IAB node and neighboring IAB donors,

step 1: the IAB node reports the assistance information to the serving donor IAB,

, the source donor IAB decides to handover based on the measurement, the source donor IAB sends a backhaul handover request to the target donor IAB,

and step 3: if resources in the target IAB donor are available, the target IAB donor will reply ACK to the source IAB donor, step 4: the source IAB donor sends a backhaul handover command to the IAB node,

, upon receiving the backhaul handover command message, the IAB node will connect to the target IAB donor,

step 6: after the IAB node is successfully connected, the target IAB donor transmits the complete backhaul switch to the source IAB donor.
3. The selection method of any of claims 1-2, further comprising a next hop IAB node reselection, wherein,

IAB node1 and IAB node2 are both within the coverage of the IAB donor, but IAB node3 is out of the coverage of the donor IAB, and therefore IAB node3 is connected to the IAB donor relayed by either IAB node1 or IAB node2,

step 0: the serving IAB donor configures the IAB node to report information, measurement results, delay or load information, step 1: the IAB node reports assistance information, measurements of backhaul links related to IAB node2 and IAB node3,

, once the IAB donor decides to perform an IAB node switch, the IAB donor sends a backhaul handover request to the target IAB node2,

and step 3: the target IAB node2 replies an ACK to the IAB donor,

and 4, step 4: the IAB donor sends a backhaul handover command to the IAB node3 relayed by the IAB node1, FFS: the contents of the backhaul handover command are transparent to IAB node1,

and 5: after receiving the backhaul handover command message, the IAB node3 connects to the target IAB node2,

step 6: after successful connection of IAB node3, the target IAB node2 will send the full backhaul switch to the donor IAB,

and 7: the IAB donor communicates the backhaul release to IAB node1,

in step 1, the IAB node will report information to help the serving donor IAB make its decision, the following information will help the donor IAB,

measurement of the link between IAB node3 and the candidate IAB node, or

Delay information of candidate IAB nodes, or

-loading information of candidate IAB nodes;

in case of IAB node reselection, the IAB node should report side information including measurement results, latency information and load information to the donor IAB.
4. The selection method of claim 3, wherein slot boundaries of the IAB node and donor IAB node should be aligned with integer multiple symbol shifts.
5. The selection method of claim 4, wherein the IAB node topology management is of two types: centralized topology management and distributed topology management; in centralized topology management, the topology of the entire IAB network is managed by a centralized entity, which maintains the global topology of the IAB network; the centralized entity is located on a donor IAB, a core network or an application server; in distributed topology management, each IAB node and IAB donor has its own topology management entity and maintains a local topology based on the exchange of information with neighboring nodes.
The node selection device of integrated access and backhaul system deployed in new wireless NR, using massive multiple input multiple output MIMO system, including multiple IAB nodes, wherein part is donor IAB node, control signaling required for enhancing LTE RRC signaling to support IAB node integration process to dynamically switch backhaul link, IAB node supporting multiplexing access link and backhaul link in TDM, FDM and SDM with half-duplex constraint, characterized in that it comprises:

selection means for, when the IAB node performs cell selection/reselection, the IAB node with a smaller number of hops back to the IAB donor should have a higher priority and the load of the IAB node should be lower.
7. The selection apparatus of claim 6, further comprising donor IAB reselection apparatus to perform the steps of, wherein,

step 0: the IAB node is configured by the serving IAB donor 1 to report information, measurements of candidate backhaul links between the IAB node and neighboring IAB donors,

step 1: the IAB node reports the assistance information to the serving donor IAB,

, the source donor IAB decides to handover based on the measurement, the source donor IAB sends a backhaul handover request to the target donor IAB,

and step 3: if resources in the target IAB donor are available, the target IAB donor will reply ACK to the source IAB donor, step 4: the source IAB donor sends a backhaul handover command to the IAB node,

, upon receiving the backhaul handover command message, the IAB node will connect to the target IAB donor,

step 6: after the IAB node is successfully connected, the target IAB donor transmits the complete backhaul switch to the source IAB donor.
8. The selection apparatus according to any of the claims 6-7, , further comprising a down hop IAB node reselection apparatus to perform the steps, wherein,

IAB node1 and IAB node2 are both within the coverage of the IAB donor, but IAB node3 is out of the coverage of the donor IAB, and therefore IAB node3 is connected to the IAB donor relayed by either IAB node1 or IAB node2,

step 0: the serving IAB donor configures the IAB node to report information, measurement results, delay or load information, step 1: the IAB node reports assistance information, measurements of backhaul links related to IAB node2 and IAB node3,

, once the IAB donor decides to perform an IAB node switch, the IAB donor sends a backhaul handover request to the target IAB node2,

and step 3: the target IAB node2 replies an ACK to the IAB donor,

and 4, step 4: the IAB donor sends a backhaul handover command to the IAB node3 relayed by the IAB node1, FFS: the contents of the backhaul handover command are transparent to IAB node1,

and 5: after receiving the backhaul handover command message, the IAB node3 connects to the target IAB node2,

step 6: after successful connection of IAB node3, the target IAB node2 will send the full backhaul switch to the donor IAB,

and 7: the IAB donor communicates the backhaul release to IAB node1,

in step 1, the IAB node will report information to help the serving donor IAB make its decision, the following information will help the donor IAB,

measurement of the link between IAB node3 and the candidate IAB node, or

Delay information of candidate IAB nodes, or

-loading information of candidate IAB nodes;

in case of IAB node reselection, the IAB node should report side information including measurement results, latency information and load information to the donor IAB.
9. The selection apparatus of claim 8, wherein slot boundaries of the IAB node and donor IAB node should be aligned with integer multiple symbol shifts.
10. The selection apparatus of claim 9, wherein the IAB node topology management is of two types: centralized topology management and distributed topology management; in centralized topology management, the topology of the entire IAB network is managed by a centralized entity, which maintains the global topology of the IAB network; the centralized entity is located on a donor IAB, a core network or an application server; in distributed topology management, each IAB node and IAB donor has its own topology management entity and maintains a local topology based on the exchange of information with neighboring nodes.