KR20160046230A - Group communication method using hierarchical cluster head in mobile communication system - Google Patents

Abstract

A cluster between terminals performing group communications in a mobile communications system is formed. If a signal reception impossibility terminal is discovered among the terminals performing group communications, a cluster head designates a sub head among the terminals performing the group communications. If the terminal to receive information from the sub head cannot receive the information, the cluster head designates a sub-sub head. If a signal reception impossibility situation vanishes, the cluster head removes the sub head or sub-sub head designation.

Description

TECHNICAL FIELD [0001] The present invention relates to a group communication method using a hierarchical cluster head in a mobile communication system,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a group communication method using a hierarchical cluster head in a mobile communication system, and more particularly, to a method of performing group communication through a direct radio link between terminals in a mobile communication system.

In 3GPP, D2D (Device-to-Device) standardization for direct communication between adjacent terminals is underway without going through a base station.

The synchronization and system information broadcasting and resource allocation for D2D communication between the terminals are classified into a central control system and a distributed control system as shown in FIG.

FIG. 1 shows a conventional control method for inter-terminal D2D communication. FIG. 2 shows a state in which some of the members of the cluster can not receive a signal broadcast by a head. FIG. This indicates a problem that arises when the transmission power is increased.

First, referring to FIG. 1, the central control scheme is a scheme in which a base station or a specific terminal performs synchronization, system information broadcast, and resource allocation functions. The distributed control method is a method in which each terminal participating in communication acquires synchronization and system information with the same qualification and acquires resources through competition.

When all of the D2D communication terminals are within the area of the base station, a central control scheme through the base station is possible as shown in FIG. However, when there exist terminals existing outside the base station area, these terminals can not receive signals of the base station. Accordingly, as shown in FIG. 1 (b), a cluster is configured between terminals that communicate with each other, a head representative of the cluster is selected, and the selected cluster head performs control functions provided by the base station.

In this case, all the members of the cluster must receive the synchronization signal and system information broadcast by the head, thereby synchronizing for communication with the group members and acquiring the configuration information set for the wireless transmission. It also communicates with group members using resources allocated by the head. In D2D communication, not only the members of the cluster but also the representative head itself have independent mobility. Therefore, sometimes, as shown in FIG. 2, some of the members of the cluster may not receive a signal broadcast by the head.

To solve these problems, the following measures can be considered.

One approach is to increase the transmit power of the head. At this time, as shown in (a) of FIG. 3, the cluster head increases the transmission power and transmits the signal to a wider area. However, such a scheme increases the number of signal overlap regions with neighboring clusters as shown in FIG. 3 (b), which may cause performance degradation due to inter-cluster interference. In addition, when a member enters a signal shadow area such as a paper or a tunnel, it may be impossible to transmit a signal only by increasing the transmission power.

Another option is to configure separate clusters between members that are not receivable. If the representative head does not receive the broadcasted information, it can construct a new cluster with members in the same situation in the vicinity and select the representative head. However, in case of group communication, if communication group consists of several clusters and there is a separate head in each cluster, it is difficult to use the same synchronization and resources among independent cluster heads, There is a problem.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a group communication method using a hierarchical cluster head for dynamically establishing and releasing hierarchical subheads in order to solve the problem of failure in group communication between terminals.

According to one embodiment of the present invention, a group communication method is a group communication method using a cluster head in a mobile communication system, the method comprising: configuring a cluster between terminals performing group communication; The cluster head designates a subhead among the terminals that perform group communication, and when the terminal receiving the information from the subhead can not receive information, the cluster head transmits the information to the terminal And designating an adjacent terminal as a sub-subhead, and when the signal reception disabled state disappears, the cluster head releases the subhead or the sub-subhead designation.

According to an embodiment of the present invention, when there is a group circle that can not receive information transmitted from the representative cluster head according to independent movement of the terminal, there is a problem that the cluster needs to be divided or the transmission output of the representative cluster head is increased Thereby solving the problem of increasing the influence of interference on the surrounding cluster. That is, there is an effect that the inter-terminal group communication can be maintained by setting and releasing dynamically hierarchical subheads.

FIG. 1 shows a conventional control method for inter-terminal D2D communication.
FIG. 2 is a block diagram showing a state in which some of the members of the cluster can not receive a signal broadcast by a head.
FIG. 3 shows a problem that arises when the transmission output of the head is conventionally increased.
4 is a flowchart illustrating a group communication method according to an embodiment of the present invention.
FIG. 5 is a diagram illustrating an exemplary configuration of clusters between terminals performing group communication according to an embodiment of the present invention. Referring to FIG.
FIG. 6 is a flowchart illustrating a process of configuring a cluster between terminals performing group communication according to an embodiment of the present invention.
FIG. 7 is an exemplary diagram illustrating a situation in which a signal-incapable-capable terminal is found according to an embodiment of the present invention.
FIG. 8 is a flowchart illustrating a process of discovering a non-signal-incapable terminal according to an embodiment of the present invention.
9 is a diagram illustrating an example of a subhead designation according to an embodiment of the present invention.
10 is a flowchart illustrating a process of designating a subhead according to an embodiment of the present invention.
11 is a diagram illustrating an example of releasing a subhead according to an embodiment of the present invention.
12 is a flowchart illustrating a process of releasing a subhead according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, a terminal may be referred to as a user equipment (UE), a mobile terminal (MT), a mobile station (MS), an advanced mobile station (AMS) a high reliability mobile station (HR-MS), a subscriber station (SS), a portable subscriber station (PSS), an access terminal (AT) MS, AMS, HR-MS, SS, PSS, AT, and the like.

Also, a base station (BS) includes a node B, an evolved node B, an advanced base station (ABS), a high reliability base station (HR- (BS), an access point (AP), a radio access station (RAS), a base transceiver station (BTS) BS AP, RAS, BTS, and the like.

According to the embodiment of the present invention, terminals performing group communication constitute a cluster, and a cluster is connected to a representative terminal, that is, a cluster head, for other terminals constituting a cluster, i.e., cluster members, And allocates communication resources.

The group communication method through the hierarchical cluster head according to the embodiment of the present invention is a method of communicating with a cluster head in which the head moves away from the cluster head or enters a weak signal area, When a cluster member occurs, it designates and operates a sub-cluster head that replaces its role according to the control of the cluster head. The group communication method includes a procedure of releasing the sub-cluster head when all the members can receive information broadcast by the cluster head.

According to the embodiment of the present invention, in order to minimize the problem of interference increase in the surrounding cluster by forming one cluster and increasing the transmission power of the representative cluster head, Dynamically sets and releases subcluster heads for unreceivable cluster members.

In the embodiment of the present invention, a central control scheme for group communication is used. The central control method is a method in which a base station or a specific terminal performs synchronization and system information broadcasting and resource allocation functions. At this time, a central control system based on the heads of the clusters formed between the terminals other than the base station is used. It is assumed that a terminal performing group communication constitutes one cluster.

Now, a group communication method using a hierarchical cluster head in a mobile communication system according to an embodiment of the present invention will be described in detail with reference to the drawings.

4 is a flowchart illustrating a group communication method according to an embodiment of the present invention.

Referring to FIG. 4, a cluster is established between terminals performing group communication (S101). Next, when a signal incapable terminal is found among the terminals performing group communication (S103), a subhead is designated among the terminals performing group communication excluding the cluster head (S105). Then, a hierarchical subhead is designated (S107). Thereafter, when the signal reception impossible state disappears, the subhead is released (S109).

Here, the steps S101 to S10 will be described in detail.

6 is a flowchart illustrating a process of configuring a cluster between terminals performing group communication according to an embodiment of the present invention. FIG. 5 is a flowchart illustrating a process of configuring a cluster between terminals performing group communication according to an embodiment of the present invention. to be. At this time, step S101 of FIG. 4 is detailed, and step S101 is a preliminary step for performing group communication according to an embodiment of the present invention.

Referring to FIGS. 5 and 6, a cluster is established between the terminals 100, 200, 300, and 400 that perform group communication (S201). That is, the terminals 100, 200, 300, and 400 participating in the group communication constitute one cluster. Here, the cluster means a group of terminals capable of communicating over a single or multi-hop wireless transmission.

Next, a representative head for the cluster configured in step S201 is selected (S203). For example, the terminal UE-0 is selected as a cluster head.

Next, the UE-0 (100) selected as the cluster head broadcasts synchronization and system information for the cluster members (200, 300, 400) (S205). That is, when an arbitrary source terminal desires group communication, it allocates resources and transmits allocation information to a source terminal through a signaling message. The source terminal transmits data to the group members through the corresponding resource.

FIG. 7 is a diagram illustrating a situation in which a non-signal-incapable terminal according to an exemplary embodiment of the present invention is found, and FIG. 8 is a flowchart illustrating a process of finding a non-signal incapable terminal according to an exemplary embodiment of the present invention. At this time, step S103 of FIG. 4 is described in detail.

Referring to FIGS. 7 and 8, the movement of the UE, for example, the UE-3 400 receives the synchronization and system information and the resource allocation information transmitted by the cluster head (S301) (S303).

At this time, the terminal that has failed to receive information, i.e., the terminal (UE) -3 (400) searches for a group source terminal in the vicinity (S305). UE-3 (400) is located outside the coverage of the group.

When there is a group circle, that is, a terminal (UE) -2 300, the terminal UE-2 300 transmits a terminal discovery response to the terminal discovery request (S305) (S307).

The terminal (UE) -3 (400) transmits a reception disable state to the terminal (UE) -2 (300) (S309). Then, a terminal that can not receive a signal is detected (S311).

When the UE-2 300 can communicate with the representative cluster head 100, the UE-2 300 notifies the representative cluster head 100 of the communication with the representative cluster head 100 (S313).

If the UE-2 300 having received the non-receivable status can not communicate with the representative cluster head 100, it is not possible to communicate with the representative cluster head 100 at step S305 Step S309 is repeated.

FIG. 9 is a view illustrating a state of designating a subhead according to an embodiment of the present invention, and FIG. 10 is a flowchart illustrating a process of designating a subhead according to an embodiment of the present invention. At this time, step S105 of FIG. 4 is described in detail.

Referring to FIGS. 9 and 10, the representative cluster head 100 notified of the group resource failure in receiving the information in step S313 of FIG. 8 transmits synchronization and system information and resource allocation information (S401). Here, when the representative cluster head 100 has one or more subhead candidates, the optimal cluster head is selected as the subhead considering the number of transmission hops and the transmission power.

In step S401, the UE-2 300 designated as a subhead operates as a subhead (S403). That is, when the representative cluster head 100 broadcasts the synchronization signal, the system information, the resource allocation information, and the group communication data in step S405, the subhead 300 transmits the information received in step S405 to the terminal UE- (S407).

At this time, a hierarchical subhead designation is made. That is, when the terminal receiving the information from the subhead 300 enters the shadow area or the like and is unable to receive information, the subhead 300 selects a sub-subhead that performs its role through steps S401 to S407 can do.

FIG. 11 is a view illustrating a state of releasing a subhead according to an embodiment of the present invention, and FIG. 12 is a flowchart illustrating a process of releasing a subhead according to an embodiment of the present invention. At this time, step S109 of FIG. 4 will be described in detail.

Referring to FIGS. 11 and 12, the representative cluster head 100 broadcasts synchronization signal, system information, resource allocation information, and group communication data (S501).

(UE-3) 400 receiving information from a UE (UE) -2 300 designated as a subhead in FIGS. 9 and 10 detects reception of information transmitted from the representative cluster head 100 (S503) , It notifies the representative cluster head 100 of a signal receivable report (S505).

The representative cluster head 100 determines whether there is a terminal receiving information from the subhead 300 (S507).

If so, the process returns to step S505. On the other hand, if there is no terminal receiving information from the subhead 300, the subhead 300 is notified of the subhead release (S509).

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It belongs to the scope of right.

Claims (1)

A group communication method using a cluster head in a mobile communication system,
Configuring a cluster between terminals performing group communication,
A step of finding a signal incapable terminal among the terminals performing group communication,
The cluster head designating a subhead among terminals performing group communication,
When the terminal receiving information from the subhead can not receive information, the cluster head designates the terminal adjacent to the terminal not capable of receiving the information as a sub-subhead, and
When the signal reception disabled state disappears, the cluster head releases the subhead or the sub-subhead designation
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