KR101034380B1 - System and Method for security of Neighborhood Area Network using neighborhood detection - Google Patents

Abstract

The present invention relates to a security method and apparatus, and more particularly, to a system and method for network security using neighbor search in a neighbor area network (NAN).

In accordance with an embodiment of the present invention, a network security system using neighbor search in a NAN includes: an access node accessing a new cluster through a predetermined parent node; And a coordinator for transmitting a neighbor search request to the access node to receive an extended ACL frame generated by the neighbor search from the access node, wherein the extended ACL frame is a neighbor representing neighbor nodes within one hop of the access node. List fields; And a neighbor node time stamp field indicating time information of radio resources allocated to the neighbor nodes, respectively.

Neighbor Discovery, NAN, Cluster Structure

Description

System and Method for Security of Neighborhood Area Network using neighborhood detection}

The present invention relates to a security system and method, and more particularly, to a system and method for network security using neighbor search in a neighbor area network (NAN).

Wireless short-range networking technologies include radio-frequency identification (RFID), Bluetooth, and Zigbee. For example, the application of wireless short-range networking technology is expected to grow rapidly in various fields such as home network, building, industrial device automation, environmental monitoring, medical field, automotive communication, etc. to form a wide market.

For example, in the home network field, the service is changing from the wall pad function and the control service of home appliances to the service based on the wireless network infrastructure inside the home. However, it is a simple home auto level such as remote meter reading or lighting control due to the sluggishness of standardization of interface between devices and security and protocol problems, and security problem in the field of entertainment and information service based on home server and digital appliances, which are the main network in home network. When it comes to stepping out of step.

As such, research on transmission and reception speeds is mainly performed in short-range communication, and a security technique and a system capable of preventing malicious access to forgery of a message or generating a large amount of packets throughout a network are needed.

According to an embodiment of the present invention, there is provided a system and method capable of maintaining security in a neighbor area network (NAN) by blocking a network connection to a malicious node by neighbor search.

In addition, it is to provide a system and method that can block the access of the malicious node by reflecting the information according to the neighbor search in the extended ACL frame.

The objects of the present invention are not limited to the above-mentioned objects, and other objects that are not mentioned will be clearly understood by those skilled in the art from the following description.

In order to achieve the above technical problem, an aspect of a network security system using neighbor search in a NAN of the present invention includes: an access node accessing a new cluster through a predetermined parent node; And a coordinator for transmitting a neighbor search request to the access node to receive an extended ACL frame generated by the neighbor search from the access node, wherein the extended ACL frame is a neighbor representing neighbor nodes within one hop of the access node. List fields; And a neighbor node time stamp field indicating time information of radio resources allocated to the neighbor nodes, respectively.

In order to achieve the above technical problem, an aspect of a network security method using neighbor search in a NAN according to the present invention includes accessing a predetermined cluster from an access node, receiving an initial synchronization beacon, and performing synchronization; And transmitting a neighbor search request to the access node to receive an extended ACL frame generated by the neighbor search from the access node, wherein the extended ACL frame is a neighbor representing neighbor nodes within one hop of the access node. List fields; And a neighbor node time stamp field indicating time information of radio resources allocated to the neighbor nodes, respectively.

Another aspect of the network security method using the neighbor search in the NAN of the present invention to achieve the above technical problem is the step of accessing a predetermined cluster from the access node to receive an initial synchronization beacon; Receiving the address of the access node and the generated random number key from the access node, and transmitting a neighbor search request to the access node; Receiving an extended ACL frame according to the neighbor node search; Selecting one node from a list of neighbor nodes collected according to a neighbor search from the access node, and receiving a first encryption key generated by calculating an address, a random key, and a master key of the selected node; Extracting the selected node by decrypting the first encryption key by the random number key and the master key; And determining whether the information of the selected node coincides with the selected node information extracted from the extended ACL frame.

According to an embodiment of the present invention as described above, the NAN (Neighborhood Area Network) can detect and block the connection of the malicious node by neighbor search.

In addition, even if a malicious node replicates the neighboring node, by introducing a time stamp of the corresponding node according to the neighbor search, the hacking node can be detected more securely and securely.

The effects of the present invention are not limited to the above-mentioned effects, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims.

Specific details of other embodiments are included in the detailed description and the drawings. Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various different forms, and only the embodiments make the disclosure of the present invention complete, and the general knowledge in the art to which the present invention belongs. It is provided to fully inform the person having the scope of the invention, which is defined only by the scope of the claims. Like reference numerals refer to like elements throughout.

1 is a view schematically showing a network of a general cluster structure. Referring to FIG. 1, in a NAN (Neighborhood Area Network), a network may be formed in a structure of predetermined clusters 100 and 200. For example, the predetermined network may be divided into a first cluster 100 managed by the first coordinator 110 and a second cluster 200 managed by the second coordinator 210.

The coordinator 110, 210 is responsible for radio resource allocation and radio resource control of the nodes 120, 121, 122, 123, 124, 220, 221, 222, and 223 belonging to the cluster 100, 200. Control data transmission and reception of each node (120, 121, 122, 123, 124, 220, 221, 222, 223) in (100, 200).

Nodes 120, 121, 122, 123, 124, 220, 221, 222, and 223 may be divided into parent nodes 120 and 220 and child nodes 121, 122, 123, 124, 221, 222 and 223. Can be. The parent nodes 120 and 220 use the radio resource allocation information and control information generated from the coordinator 110 and 210 as child nodes 121, 122, 123, 124, 221, 222, and 223 which are their subgroup nodes. To pass.

The child nodes 121, 122, 123, 124, 221, 222, and 223 are movable nodes, and may be connected to each cluster 100 and 200 or may move from one cluster to another cluster. The child nodes 121, 122, 123, 124, 221, 222, and 223 may be parent nodes when another new node connects to the subgroup.

FIG. 2A is a diagram illustrating a data structure of a general ACL frame, and FIG. 2B is a diagram illustrating an ACL data structure of a coordinator in the cluster structure of FIG. 1.

Referring to FIG. 2A, a typical NAN (Neighborhood Area Network) may generate a data structure of an ACL frame using information of a node, and may provide a predetermined level of security through updating and exchanging this.

For example, the ACL frame 270 may include an address field 241, a security field 242, a key field 243, a vector field 244, and a counter field 245. Here, the ACL frame 270 is an Access Control List frame, and refers to an information list of nodes that access the cluster or access the network through a predetermined parent node.

The address field 241 refers to an address that identifies a given node. For example, the address field 241 may list MAC addresses representing hardware or addresses in the form of IP and ID.

The security field 242 is a field representing a general security level. For example, the security level may be None, AES, AES-CCM, AES-CBC-MAC, or the like.

The key field 243 refers to an encrypted key generated by the coordinator. The key field may be an encrypted ACL key or may have a different ACL key for each node or each layer. For example, one parent node can have a K1 key, and child nodes below it can have a K2 key value.

The vector field 244 serves to provide an initial vector so that the same key is not repeated when encrypting the key.

The counter field 245 is composed of a frame counter and a key sequence, and serves to prevent an error in encrypting packets different from each other.

However, in the general ACL frame structure, since there is no key for distinguishing clusters, it is possible to distinguish a cluster from other clusters by allocating the same master key within a cluster.

As such, since each cluster shares a master key with registered nodes, when the master key is shared without encryption, a malicious node may intercept the master key, listen to the transmission messages of other registered nodes, and forge and forge. .

Referring to FIG. 2B, as shown in FIG. 1, the ACL frame 271 in the first coordinate 110 belonging to the first cluster 100 includes all nodes PN1 and N4 belonging to the first cluster 100. , N5, N6, and N7) may be an ACL frame including a plurality of data structures.

In addition, the ACL frame 272 in the second coordinate 210 belonging to the second cluster 200 is the ACL frame 272 of all the nodes (PN2, N1, N2, N3) belonging to the first cluster 200 It can be represented by a plurality of data structures.

In the above-described ACL frames 271 and 272, the information on each node located under the coordinator 110 and 210 or a predetermined node indicates the ACL frame structure, but the master key under each cluster 100 and 200 is exposed or The exposure of ACL key values in key fields poses a risk of forgery to the malicious node. On the other hand, even if there is a malicious access by the malicious node, the ACL frame structure cannot easily identify the access of the malicious node. Here, a malicious node is a non-normal node that accesses a network system, generates excessive load, disturbs the system, or generates a duplicate node using its information to generate unnecessary traffic in the network.

Therefore, in an embodiment of the present invention, the ACL frame is expanded or modified by neighboring search to easily identify the hacking node's access, thereby preventing access and duplication of malicious nodes to maintain security.

3 is a flowchart of a security method using neighbor search in a NAN according to an embodiment of the present invention. Referring to FIG. 3, first, a new node approaches a predetermined cluster, and requests a coordinated connection to the cluster (S310). Hereinafter, the new node will be referred to as a "connection node" for connecting to the cluster.

The coordinator determines the network or cluster access authority or access permission of the access node, and prepares resource allocation for accessing the cluster of the access node. The coordinator may perform basic resource allocation and authentication for data transmission and reception to the access node through the parent node of the access node. In addition, according to an embodiment of the present invention, a predetermined test process may be performed as follows to determine whether the access node is a malicious node.

The coordinator allocates a slot for communication between the access node and the neighbor nodes (S320). A predetermined message may be exchanged between the access node and neighbor nodes of the access node through the assigned slot. Here, a slot refers to a part of available radio resources such as a predetermined time and / or frequency. For example, if there are 16 time slots per round, up to 16 time slots may be allocated. Here, the neighbor node refers to a node within one hop from the access node or within a predetermined metric range defined by a neighbor area network (NAN).

The access node and the neighbor nodes may exchange messages with each other in the assigned slots (S330). For example, the access node may transmit a specific message such as a hello message indicating whether the neighbor node is present or not connected with the neighbor nodes. This hello message can be broadcast to neighbor nodes.

Nodes receiving the message generate an extended ACL frame, which will be described later, by neighbor search for neighbor nodes (S340). Here, the extended ACL frame refers to a frame that lists the ACL list of neighboring nodes around its own node. In other words, while transmitting and receiving a predetermined message through each assigned slot, it is possible to know the information of neighboring nodes surrounding itself, and can generate an extended ACL frame based on this information. The extended ACL frame is a frame generated in one embodiment of the present invention and may include a neighbor node list by neighbor search and neighbor time stamp information assigned to the neighbor node. Here, the time stamp information refers to a time slot in which a predetermined node transmits a message, and each node may receive a predetermined time slot allocated from the coordinator and transmit and receive a message in the corresponding time slot.

The access node or neighbor nodes send the extended ACL frame to the coordinator through the parent node. The coordinator compares the cluster information with the extended ACL frame with the cluster information (S350). Here, the cluster information may include information of nodes belonging to a predetermined cluster. The cluster information may be a frame having the same structure as the extended ACL frame, or may be a predetermined data structure indicating the cluster information including neighbor node list information and neighbor node time stamp information included in the extended frame. Meanwhile, in an embodiment of the present invention, "transmitting an extended ACL frame" may be defined as transmitting an extended ACL frame or transmitting information extracted from the extended ACL frame. For example, it may be understood to extract and transmit information of a neighbor list field and a neighbor node time stamp field, which will be described later, in the extended ACL frame.

The coordinator already has the updated cluster information due to the access of the new road, and can compare it with the extended ACL frame generated by the neighbor search and transmitted to the coordinator (S350). Thus, the coordinator may compare some of the cluster structure extracted by the extended ACL frame based on the cluster information and the neighbor search that the coordinator has, and may determine the existence of the malicious node when there is a difference.

If there is a malicious node, the coordinator blocks the access of the malicious node connecting to the network (S360). The connection blocking of the network may be performed by blocking the connection of the network such as canceling radio resource allocation to the malicious node.

4 illustrates an extended ACL frame structure generated according to a neighbor search in a NAN according to an embodiment of the present invention. Referring to FIG. 4, an extended ACL frame generated according to a neighbor search according to an embodiment of the present invention may further include a neighbor list field 446 and a neighbor node time stamp field 447 in a general ACL data structure. have.

For example, a generic ACL frame may include an address field 441, a security field 442, a key field 443, a vector field 444, and a counter field 445. Here, the ACL frame 270 is an Access Control List frame and refers to a list representing information of nodes that access the cluster or access the network through a predetermined parent node. Since the address field 441, the security field 442, the key field 443, the vector field 444, and the counter field 445 have been described in detail with reference to FIG. 2, the neighbor list field 446 and The neighboring node time stamp field 447 will be described in detail below.

The neighbor list field 446 is a data field indicating an identifier or number identifying a neighbor node of the node. For example, if there are three neighboring nodes around the access node, three extended ACL frames are generated, and the neighbor list field 446 of each extended ACL frame may contain an identifier or number identifying the neighboring node. have.

The neighbor node time stamp field 447 is a field indicating a time stamp of a neighbor node corresponding to the neighbor list field 446. For example, when the neighbor node transmits a message in the second time slot, the neighbor node time stamp field 447 may stamp the second time slot time for the neighbor node. In general, when a coordinator allocates a specific time slot to each neighboring node for a plurality of slots for neighbor search, the neighboring nodes may transmit and receive a predetermined message in a specific time slot given to each other. Therefore, normal nodes can send and receive messages in a specific time slot, while abnormal malicious nodes cannot send and receive messages in a specific time slot.

As described above, the extended ACL frame 400 may be generated by adding the neighbor list field 446 and the neighbor node time stamp field 447 by neighbor search. By the extended ACL frame 400, a malicious node can be easily extracted. Malicious node extraction will be described in more detail later.

5A shows a schematic diagram of detecting a malicious node according to a neighbor search in a NAN according to an embodiment of the present invention. FIG. 5B shows the extended ACL frame structure collected by the access node in FIG. 5A.

Referring to FIG. 5A, nodes of a predetermined cluster structure may form a network around the coordinator C. FIG. Nodes N1, N2, N3, and N4 that are primarily connected to the coordinator C may be configured. Among them, the N2 node becomes a parent node and may have child nodes N20, N21, and N22 below. This hierarchical structure may be determined by the key value of the key field in FIG. 5B, and the key value is different for each hierarchical layer (for example, the key values of the nanny nodes are K2, the child nodes are K3, and the child nodes are K1). Can have a key value.

Meanwhile, it is assumed that N20, N21, and N22 child nodes connected to the N2 parent node are normal nodes, and N220, N221, and N222 child nodes of N22 are malicious nodes. N22 receives the ACL key from the coordinator C through the parent node N2 and can normally connect to the cluster. However, N22 may generate duplicate nodes such as N220, N221, and N222 which are abnormal malicious nodes in order to generate wrong network traffic.

In this process, the new access node N22 may perform neighbor search. N22 may search for a parent node N2, a neighbor node N20, N22, and a child node N220, N221, N222 by neighbor search. Accordingly, as shown in FIG. 5B, the N22 access node may include N2, N20, N22, N220, N221, and N222 as an NHS list.

However, the coordinator has N1, N2, N3, N4, N20, N21, and N22 as a list of nodes normally connected in a predetermined cluster structure. In addition, the coordinator C has only N2, N20, and N22 as the normal neighbor list (NHS List) of the newly connected node N22. Accordingly, the coordinator C compares the neighbor list field of the node with the neighbor list field 446 generated by the neighbor search of the corresponding node, and detects N220, N221, and N222, which are malicious nodes generating abnormal traffic. Can be.

As described above, by comparing the neighbor list 446 generated by the coordinator and the neighbor list generated by the neighbor search, an abnormal malicious node can be easily extracted.

As another example, the neighbor node time stamp field 447 may be used to determine a malicious node. The coordinator C may instruct each node to allocate a radio resource for a predetermined time slot while instructing each node to search for a neighbor. Thus, each normal node may be assigned a specific time slot for neighbor search. Therefore, after receiving the neighbor search command from the coordinator (C), each node can send and receive a predetermined message in the time slot given to it. When the access node transmits and receives a predetermined message from neighbor nodes, the normal node may check the specific time stamp by transmitting the message in the assigned time slot.

For example, in the neighbor search in FIG. 5A, the coordinator C allocates 6 time slots for N2, 9 time slots for N20, and 10 time slots for N22. N220, N221, and N222 may allocate time slots 12, 13, and 14, respectively. Thus, normal nodes N2, N20, N22 send messages in a given time slot, making the neighbor search successful.

However, the replication nodes N220, N221 and N222 cannot transmit and receive messages in a given time slot. In a non-normal state, a replicated node cannot send or receive messages in a specific time slot for neighbor search in the coordinator. This is simply because the node cannot be sent or received in physical time.

Therefore, when the coordinator receives the extended ACL frame 400 of the N22 node that performed the neighbor search, the neighbor node time stamp field 447 may be checked to determine the malicious nodes N220, N221, and N222.

As described above, according to an embodiment of the present invention, an extended ACL frame may be generated by neighbor search, and received by the coordinator to determine whether the node is a malicious node. The extended ACL frame includes a neighbor list field 446 and a neighbor node time stamp field 447 so that the malicious node can be easily determined by this data field.

6 is a flowchart of a security method using neighbor search according to another embodiment of the present invention. Referring to FIG. 6, the access node may access an cluster managed by a predetermined coordinator and undergo an initial synchronization process (S605 and S610). For example, a predetermined synchronization process through a beacon may be performed. On the other hand, it is assumed that security between the coordinator and the parent node is intact.

Subsequently, the coordinator requests an address Add _nn and an arbitrary random key K _{ran from} the access node accessing the cluster (S612 and S615). The access node generates a random number key and transmits its own information including the address Add _nn and the random number key K _ran to the coordinator (S620). Here, the address Add _nn serves as an identifier for identifying the access node, and may include, for example, a MAC address representing a device of the access node or an IPv6 type address of the access node.

The coordinator generates a master key encrypted by an encryption function such as a hash function and transmits the master key to the access node through the parent node (S625 and S630). Since the access node does not know the encrypted key information, the access node cannot use it to authenticate its node using the encrypted master key.

In response, the coordinator requests a neighbor search (NHS) from a parent node and child nodes below the parent node (S635, S640, and S642).

Accordingly, neighboring nodes including the access node and the parent node may exchange messages in time slots allocated to each other (S650, S651, S652, and S653). By this message exchange, it is possible to identify neighboring nodes around its own node. However, in the neighbor search, only child nodes may send and receive messages except for the parent node. The extended ACL frame structure indicating neighbor search information may be generated by the neighbor node search.

The extended ACL frame, which is the neighbor search information obtained by the neighbor search, is transmitted to the parent node (S660, S670). The parent node transmits neighbor search information to the coordinator (S675). Here, the extended ACL frame may include a list of neighboring nodes and time stamp information of the neighboring nodes around a predetermined node.

The access node selects an arbitrary node k from the neighbor node list retrieved by the neighbor search, and performs an XOR operation on the encrypted master key and the random key (Add _k || Random key || Master key) to select the first encryption key. Create In this way, the generated first encryption key is transmitted to the coordinator (S680). Since the coordinator already has the master key and the Lambton key of the access node, XOR operation is performed on the first encryption key information received from the access node with the master key and the random key of the access node by double decryption to select k nodes selected by the access node. Can be extracted (S685).

The coordinator compares the decrypted k node information with the extended ACL frame information received from the parent node (S687). In the same case, the coordinator performs an XOR operation with the random key received from the access node to generate the ACL key, which is the second encryption key, and transmits the master key to the access node as a value of the ACK key field (S690). Therefore, the security maintenance can be improved by transmitting the encrypted key field 443 instead of the key field 443 transmitted and received in plain text.

The access node decrypts the encrypted ACL key field value with its own random key and transmits master key information to the coordinator (S693). The coordinator performs authentication through the master key, and registers the access node as a normal node (S695).

As described above, by selecting an arbitrary k node among neighboring nodes by neighbor search and using an encrypted ACL key field, other nodes accessing the cluster intercept the ACK key field to hack or down the cluster. Can prevent the activity of

Meanwhile, in another embodiment, even when collecting information of one neighbor node, the coordinator may not respond to a desired allocation time because one of the plurality of keys generated by the number of neighbor nodes needs to be decrypted. In addition, when a single node duplicates and generates a plurality of nodes, it cannot respond by assigning all keys and the allocated time to the time allocated by the coordinator. Even if the malicious node replicates the neighbor node k, since the slot information contained in the neighbor node time stamp field 447 is not known, the malicious node cannot respond to the corresponding time slot at all. Therefore, the coordinator can easily detect the evil node.

As yet another example, the coordinator may determine a malicious node through a difference between the neighbor search list and the neighbor node time stamp field generated by malicious node replication and the neighbor search list and the neighbor node time stamp field. Detection can be facilitated.

As described above, according to an embodiment of the present invention, by using the information of the neighbor nodes obtained according to the neighbor search, the malicious node is easily carried out with the resource information of the node even without introducing a complicated calculation and authentication process for encryption. Can be extracted.

Although embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art to which the present invention pertains have various permutations, modifications, and modifications without departing from the spirit or essential features of the present invention. It is to be understood that modifications may be made and other embodiments may be embodied. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

1 is a view schematically showing a network of a general cluster structure.

2A is a diagram illustrating a data structure of a general ACL frame.

FIG. 2B is a diagram schematically illustrating an ACL data structure in the coordinator in the cluster structure of FIG. 1.

3 is a flowchart of a security method using neighbor search in a NAN according to an embodiment of the present invention.

4 is a diagram illustrating an extended ACL frame structure generated according to a neighbor search in a NAN according to an embodiment of the present invention.

5A is a schematic diagram of detecting a malicious node according to a neighbor search in a NAN according to an embodiment of the present invention.

FIG. 5B is a diagram illustrating an extended ACL frame structure collected by an access node in FIG. 5A.

6 is a flowchart of a security method using neighbor search in a NAN according to another embodiment of the present invention.

* Description of the main parts of the drawings *

100, 200: cluster

120, 220: Coordinator

270, 271, 272: ACL frame

400: extended ACL frame

Claims (12)

An access node accessing a new cluster through a given parent node; And A coordinator for transmitting a neighbor search request to the access node to receive an extended ACL frame generated by the neighbor search from the access node, The extended ACL frame is A neighbor list field indicating neighbor nodes within one hop of the access node; And And a neighbor node time stamp field indicating time information of radio resources allocated to the neighbor nodes, respectively. The method of claim 1, And the coordinator determines whether a malicious node exists by using the neighbor list field and the neighbor node time stamp field included in the received extended ACL frame. 3. The method of claim 2, And the coordinator compares cluster information indicating information of nodes belonging to a predetermined cluster with information extracted from the received extended ACL frame to determine whether the node is a malicious node. The method of claim 1, The Neighbor Time Stamp field indicates a time slot allocated by the coordinator for transmission and reception of messages between the access node and the neighbor node. The method of claim 1, The access node transmits the extended ACL frame information by setting a time slot number or time for receiving a specific message from the neighbor node to a value of a neighbor node time stamp field of the neighbor node. Security system. Accessing a predetermined cluster from an access node, receiving an initial synchronization beacon, and performing synchronization; And Sending a neighbor search request to the access node to receive an extended ACL frame generated by the neighbor search from the access node, The extended ACL frame is A neighbor list field indicating neighbor nodes within one hop of the access node; And And a neighbor node time stamp field indicating time information of radio resources allocated to the neighbor nodes, respectively. The method of claim 6, And comparing cluster information including information of nodes belonging to a predetermined cluster with information extracted from the received extended ACL frame to determine whether the node is a malicious node. The method of claim 6, The value of the neighbor node time stamp field of the neighbor node is a value indicating a time slot number or time at which the access node receiving the neighbor search request receives a hello message from the neighbor node. Way. Accessing a predetermined cluster from an access node to receive an initial synchronization beacon; Receiving the address of the access node and the generated random number key from the access node, and transmitting a neighbor search request to the access node; Receiving an extended ACL frame according to the neighbor node search; Selecting one node from a list of neighbor nodes collected according to a neighbor search from the access node, and receiving a first encryption key generated by calculating an address, a random key, and a master key of the selected node; Extracting the selected node by decrypting the first encryption key by the random number key and the master key; And And determining whether or not the information of the selected node and the selected node information extracted from the extended ACL frame coincide with each other. The method of claim 9, wherein after determining whether the selected node information matches, Computing the master key and the random number key to generate a second cryptographic key and transmit the second encryption key to the access node. The method of claim 9, And said master key represents an encrypted key assigned to said predetermined cluster in a coordinator. The method of claim 9, The extended ACL frame is A neighbor list field indicating neighbor nodes within one hop of the access node; And And a neighbor node time stamp field indicating time information of radio resources allocated to the neighbor nodes, respectively.

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