KR102056717B1 - Signalling method for direct communication between terminals - Google Patents

Abstract

A signaling method of a terminal for direct communication between terminals is disclosed. The transmitting terminal transmits a link establishment request message for link establishment to the receiving terminal, and the receiving terminal transmits a link establishment response message to the transmitting terminal in response. Here, the link establishment request message includes a field indicating a flow to be used when the receiving terminal acquires a token.

Description

Signaling method for direct communication between terminals {SIGNALLING METHOD FOR DIRECT COMMUNICATION BETWEEN TERMINALS}

The present invention relates to a signaling method for direct communication between terminals.

Direct communication transmits and receives a signal between terminals without arbitration or control of a base station. As the demand for direct communication between terminals increases, there is a need for a direct communication method within or outside the infrastructure communication area.

The target standard for direct communication between terminals is IEEE Std. 802.16.1a. IEEE Std. 802.16.1a standard allocates dedicated resources for direct communication in time and frequency domain in the infrastructure communication frame structure between a base station and a terminal, and performs direct communication between terminals by exchanging signals between terminals through the allocated radio resources. .

In order to differentially provide a Quality of Service (QoS) for each trackfill in a radio resource interval, a flow is set in MAC measurement and a MAC packet data unit (PDU) is configured for each flow. Talk-around Direct Communication (TDC) of the IEEE Std. 802.16.1a standard sets a flow ID (FID, Flow Identifier) in a unidirectional link setup process, and the transmitter sets the FID not to be duplicated. However, when the direction of unidirectional traffic is changed by the token transfer procedure, a situation may occur where the traffic source is changed to the terminal that does not set the FID. In this case, a problem occurs in that the transmitting terminal does not configure the MAC PDU for the terminal for which the FID is not set.

Multicast connections are the transmission of data to multiple groups of users. In the first step of establishing a multicast connection, a connection establishment procedure is performed, thereby creating a multicast connection group. However, the existing IEEE Std. 802.16.1a standard does not present an operation scenario of a user (terminal) exiting a multicast connection group. In addition, since the procedure for transmitting the multicast connection setting information after the setting step is not defined, a user who wants to additionally participate in the multicast connection group may not participate in the multicast connection group.

In one-way unicast and multicast connections, the procedure of searching for the presence or absence of a receiving terminal at a communication distance and disconnecting a connection without a communication channel is not defined in the existing IEEE Std. 802.16.1a standard.

An object of the present invention is to provide a signaling method for establishing an FID to support a token handover procedure in a unidirectional link.

Another object of the present invention is to provide a signaling method for dynamically maintaining a multicast connection group.

Another problem to be solved by the present invention is to provide a signaling method for releasing a call when detecting whether the receiving terminal is within a communication distance and deviates.

Another problem to be solved by the present invention is to provide a signaling method for operating a plurality of dedicated channels on one link.

According to an embodiment of the present invention, a signaling method of a first terminal for direct communication between terminals is provided. The signaling method may include transmitting a first link establishment request message for establishing a direct communication link to a second terminal, and receiving a first link establishment response message for establishing a direct communication link from the second terminal. The first link establishment response message includes a first field indicating a flow to be used by the second terminal.

The first link establishment request message may further include a second field indicating a flow establishment request for token transfer.

The first link establishment response message may include a field indicating a flow establishment confirmation (Confirm) for token transfer.

The first link establishment request message may be transmitted through a request to send data portion, and the first link establishment response message may be transmitted through a clear to send data portion.

The signaling method may further include detecting a loss of the direct communication link, and if the loss of the direct communication link is detected, releasing the direct communication link.

The detecting may include determining that the direct communication link is lost when a signal is not received over a predetermined number of times among channels established between the first terminal and the second terminal.

The releasing step may include transmitting a link release indication message to the second terminal to release the direct communication link.

The signaling method may further include releasing at least one dedicated channel of the plurality of dedicated channels when the direct communication link is operated by a plurality of dedicated channels.

The step of releasing the at least one dedicated channel may include receiving a status of the plurality of dedicated channels from a second terminal and determining a dedicated channel to release among the plurality of dedicated channels, and for the dedicated channel to be released. The method may include transmitting a resource change indication message including a field for identifying a resource to the second terminal.

According to another embodiment of the present invention, a signaling method of a first terminal for direct communication between terminals is provided. The signaling method may include transmitting a token broadcast message for token notification to a plurality of second terminals, receiving a token request message from a desired third terminal having a token among the plurality of second terminals, and the third And transmitting a token response message, which is a response to the token request message, to the terminal, wherein the token request message includes a first field indicating a flow to be used by the third terminal.

The flow may be used in the multicast connection of the third terminal.

The signaling method may further include transmitting a token handover message indicating a token transfer to the plurality of second terminals.

According to another embodiment of the present invention, a signaling method of a first terminal for direct communication between terminals is provided. The signaling method may include transmitting a MAC header to a plurality of second terminals, transmitting a preamble to the plurality of second terminals, and request to send to the plurality of second terminals. ) Repeatedly transmitting, via the data portion, a link establishment indication message for establishing a direct communication link.

The signaling method may further include detecting a loss of the direct communication link, and if the loss of the direct communication link is detected, releasing the direct communication link.

The detecting may include determining that the direct communication link is lost when a signal transmitted to an auxiliary channel among channels established between the first terminal and the plurality of second terminals is lower than a clear channel threshold. It may include a step.

According to another embodiment of the present invention, a signaling method of a relay terminal for relaying direct communication between a first terminal and a second terminal is provided. The signaling method includes receiving a relay request message requesting relay information from the first terminal, and transmitting a relay response message, which is a response to the relay request message, to the first terminal. The relay response message includes a field indicating a flow to be used by the second terminal.

The signaling method may further include transmitting the relay request message to the second terminal, and receiving the relay response message including the field from the second terminal.

The relay request message may include a field indicating a flow establishment request for token transfer, and the relay response message may further include a field indicating a flow establishment confirmation for token transfer.

According to another embodiment of the present invention, a signaling method of a relay terminal for relaying direct communication between a first terminal and a plurality of second terminals is provided. The signaling method may include receiving a token handover message for token transfer from the first terminal, transmitting a token broadcast message for token notification to the plurality of second terminals, and token among the plurality of second terminals. Receiving a token request message from a third terminal wishing to have a second request; and transmitting a token response message, which is a response to the token request message, to the plurality of third terminals; 3 It includes a field indicating a flow to be used by the terminal.

The signaling method may further include transmitting a link establishment indication message including the flow to the plurality of second terminals and the third terminal.

According to an embodiment of the present invention, by additionally setting the FID to support the token transfer procedure in the unidirectional link, the terminal acquiring the token may successfully generate a packet.

According to another embodiment of the present invention, the multicast connection setup may be repeatedly performed to cope with the dynamic change of the multicast.

According to another embodiment of the present invention can provide a procedure for detecting and releasing the loss of the direct communication link.

According to another embodiment of the present invention, when a plurality of dedicated channels are operated in the direct communication link, a procedure for releasing the dedicated channel may be provided according to the state of the channel.

1 and 2 are frame structures illustrating resources for direct communication according to an embodiment of the present invention.
3 is a diagram illustrating a link establishment procedure when unidirectional unicast connection according to an embodiment of the present invention.
4 is a diagram illustrating a link establishment procedure in one-way unicast connection according to another embodiment of the present invention.
5 is a diagram illustrating a token transfer procedure in a one-way multicast connection according to an embodiment of the present invention.
6 is a diagram illustrating a link establishment procedure when a token acquiring terminal according to an embodiment of the present invention is unidirectional multicast connection.
7 is a diagram illustrating an environment in which a terminal relays a direct communication relay link.
8 is a diagram illustrating a procedure of acquiring relay information according to an embodiment of the present invention.
9 is a diagram illustrating a procedure of acquiring relay information according to another embodiment of the present invention.
FIG. 10 is a diagram illustrating an environment when a terminal is unidirectional unicast connection and multicast relay connection.
11 is a diagram illustrating a procedure for establishing a one-way unicast connection and a multicast relay connection according to an embodiment of the present invention.
12 is a view showing a token management procedure of the relay terminal according to an embodiment of the present invention.
FIG. 13 is a diagram illustrating a link establishment procedure when a relay terminal connects to a one-way multercast according to an embodiment of the present invention. FIG.
14 is a diagram illustrating a link establishment procedure in unidirectional multicast connection for dynamically maintaining a multicast connection group according to an embodiment of the present invention.
15 is a diagram illustrating a method for detecting and releasing link loss in unidirectional unicast direct communication according to an embodiment of the present invention.
16 illustrates a method of releasing a dedicated resource channel in unidirectional unicast direct communication according to an embodiment of the present invention.
17 is a diagram illustrating a method of releasing a dedicated channel in a bidirectional unicast direct communication link according to an embodiment of the present invention.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, a terminal, a mobile terminal (MT), a mobile station (MS), an advanced mobile station (AMS), a high reliability mobile station (HR-MS) May also refer to a subscriber station (SS), a portable subscriber station (PSS), an access terminal (AT), a user equipment (UE), or the like. It may also include all or part of the functionality of the HR-MS, SS, PSS, AT, UE and the like.

The base station (BS) is an advanced base station (ABS), a high reliability base station (HR-BS), a node B (node B), an evolved node B (eNodeB) An access point (AP), a radio access station (RAS), a base transceiver station (BTS), a mobile multihop relay (MMR) -BS, a relay station serving as a base station, RS), a high reliability relay station (HR-RS) serving as a base station, etc., and may also refer to ABS, Node B, eNodeB, AP, RAS, BTS, MMR-BS, RS, HR-RS. It may also include all or part of the function.

In addition, signaling for direct communication is a procedure for exchanging a MAC (Medium Access Control) control message for direct communication, and may be mixed with a signaling procedure or a MAC signal procedure.

First, a frame structure for supporting a signaling method for direct communication according to an embodiment of the present invention will be described.

1 and 2 are frame structures illustrating resources for direct communication according to an embodiment of the present invention.

1 and 2, a superframe includes a plurality of frames, and each frame includes a plurality of subframes. Some subframes within each frame may be allocated to an uplink (UL) resource region, and some other subframes may be allocated to a downlink (DL) resource region.

In the present specification, a part of the uplink resource region is illustrated as a radio resource (direct mode zone) for direct communication, but is not limited thereto. In infrastructure communication between a base station and a terminal, radio resources for direct communication may not be used. Terminals participating in direct communication may perform direct communication using a direct communication protocol and a procedure through a radio resource for direct communication.

Meanwhile, radio resources for direct communication may include a synchronization channel, a dedicated channel, and a supplementary channel. The synchronization channel may transmit a synchronization message including information for frequency or time synchronization acquisition between a transmitting terminal and a receiving terminal for direct communication between terminals. The dedicated channel may deliver a packet for direct communication between terminals. Here, the packet may include data and control information. Auxiliary channels include Request To Send (RTS) and Clear To Send (CTS) to reserve dedicated channel, ACK message indicating whether packet is successfully delivered, control message for channel measurement value, and signaling MAC control message and the like can be delivered. Radio resources for direct communication in one superframe may be divided into a synchronization part and a data part. Here, the data portion is composed of two slots, each slot may be represented by slot 1 and slot 2. Each slot may include a dedicated channel and an auxiliary channel. Here, the dedicated channel and the auxiliary channel have a 1: 1 correspondence. For example, the auxiliary channel of slot 1 may correspond to the slot 2 dedicated channel of the previous superframe. The auxiliary channel of slot 2 may correspond to the dedicated channel of slot 1 of the same superframe.

Hereinafter, a signaling method of setting a flow ID (FID) to support a token handover procedure will be described. This signaling method will be described by dividing into one-way unicast connection, one-way multicast connection, one-way unicast connection and unicast relay connection, one-way unicast connection and multicast relay connection according to the configuration of the link.

First, referring to FIGS. 3 and 4, a method of additionally configuring an FID during unidirectional unicast connection will be described.

3 is a diagram illustrating a link establishment procedure when unidirectional unicast connection according to an embodiment of the present invention.

Referring to FIG. 3, the transmitting terminal transmits an Advanced Air Interface-Direct Communication-Link Establishment-Request (AAI-DC-LEST-REQ) message to the receiving terminal for a direct communication link establishment request ( S310). A flow allocated by the transmitting terminal is set in the AAI-DC-LEST-REQ message.

The transmitting terminal negotiates whether to use a function supporting a token handover procedure through an AAI-DC-LEST-REQ message. As shown in the underlined part of Table 1 below, the transmitting terminal adds a "Flow Establishment Request for Token Handover" field to the AAI-DC-LEST-REQ message and transmits it to the receiving terminal. If this field value is set as "Not Allowed", it does not support the token handover procedure. If it is set to "Request to establishment flow for token handover", it supports the token transfer procedure.

Thereafter, the receiving terminal transmits an Advanced Air Interface Direct Communication-Link Establishment-Response (AAI-DC-LEST-RSP) message to the transmitting terminal (S320). Here, as shown in the underlined portion of Table 2, the receiving terminal adds a "Flow Establishment Confirm for Token Handover" field to the AAI-DC-LEST-RSP message and transmits it to the transmitting terminal. . If this field value is set to "Not Allowed", it does not support the token handover procedure. If it is set to "Confirm flow establishment for token handover", it supports the token transfer procedure. The "Flow Establishment Request for Token Handover" field of the AAI-DC-LEST-REQ message transmitted by the transmitting terminal is set to "Request to establishment flow for token handover", and is directly transmitted by the receiving terminal. When the "Confirm flow establishment for token handover" field of the AAI-DC-LEST-RSP message is set to "flow Establishment Confirm for Token Handover", the token transfer procedure is finally determined.

Meanwhile, the receiving terminal sets a flow to be used by the receiving terminal through an AAI-DC-LEST-RSP message. As shown in the underlined part of Table 2 below, a field for setting an additional flow (flow to be used by the receiving terminal) is added to the AAI-DC-LEST-RSP message transmitted by the receiving terminal. do. The additional flow is used to process the traffic transmitted after the receiving terminal acquires the token in the future.

4 is a diagram illustrating a link establishment procedure in one-way unicast connection according to another embodiment of the present invention.

Referring to FIG. 4, the resource allocation function and the link setting function are integrated.

After transmitting the preamble to the receiving terminal (S410), the transmitting terminal transmits the RTS, and transmits a direct communication link establishment request (AAI-DC-LEST-REQ) message through the RTS data portion (S420).

Thereafter, the receiving terminal transmits a preamble to the transmitting terminal (S430), transmits a CTS, and transmits a direct communication link establishment response (AAI-DC-LEST-RSP) message through the CTS data portion (S440).

In this case, the AAI-DC-LEST-REQ message includes a "Flow Establishment Request for Token Handover" field as described above with reference to FIG. 3 and a AAI-DC-LEST-REQ message. RSP) message includes a "Flow Establishment Confirm for Token Handover" field and a field for setting an additional flow (flow to be used by the receiving terminal).

Table 1 below shows a description of the AAI-DC-LEST-REQ message field described above, and Table 2 shows a description of the AAI-DC-LEST-RSP message field. .

Field Size  ( bits ) Value Of Description Condition Link Change Count 4 The change count of this transaction assigned by the sender. If new transaction is started, Link Change Count is incremented by one (modulo 16) by the sender. Shall always be present Flow Establishment  Request for Token Handover 4 Indicates that the sending HR - MS  requests the receiving HR - MS to  establish flows and send MAC PDUs on  the flows
0x0: Request to establish flow for  token handover
0x1: Not allowed
0x2 to  0 xF : Reserved . Shall always be present For (i = 0; i <N_Flow_Est; i ++) { N_Flow_Est is the number of flows on which the sender of this message sends MAC PDUs.
Range [0..1] FID 4 Flow identifier assigned by the sink of packets on the flow Traffic priority 3 0 to 7: Higher numbers indicate higher priority
Default: 0 CS Specification Parameters 8 0-15: Reserved
16: Voice Codec G.729A
17: Voice Codec AMR
18-255: Reserved MAC Header Type One Indicates whether AGMH or SPMH is presented at the start of MAC PDUs of the service flow.
0: AGMH (Advanced Generic MAC Header)
1: SPMH (Short-Packet MAC header)
default value is 0. }

Field Size  ( bits ) Value Of Description Condition Link Change Count 4 Link Change Count from corresponding the AAI-AAI-DC-LEST-REQ Shall always be present Confirmation Code 4 Zero indicates the request was successful. Nonzero indicates failure.
0x0: accept
0x1: reject with a recommended DCH
0x2: reject
0x3 to 0xF: reserved Shall always be present Flow Establishment  Confirm for Token Handover One Zero indicates that the sending  HR-MS of this message confirms flow establishment .
0 : Confirm flow establishment for  token handover
One : Not allowed Shall always be present Direct Mode Zone Type 2 Direct mode zone type of a recommended DCH
0x0: Common direct mode zone (CAAI-DCZ)
0x1: Common direct mode zone extended (CAAI-DCZ-E)
0x2: Cell specific direct mode zone (CSAAI-DCZ)
0x3 to 0xF: Reserved . Present if Confirmation Code == 0x1 DCH Number 6 Recommended DCH number on the zone of Direct Mode Zone Type Present if Confirmation Code == 0x1 For  (i = 0; i <N_Flow_Est; i ++) { N_ Flow _ Est is the number of flows on  which the sender of this message  sends MAC PDUs .
Range  [0..1] Present if  Confirmation Code  == 0x0 and Flow  Establishment Confirm for Token  Handover == 0x0 FID 4 Flow identifier assigned by the  source of packets on the flow Present if  Confirmation Code  == 0x0 and Flow  Establishment Confirm for Token  Handover == 0x0 Traffic Priority 3 0 to  7: Higher numbers indicate  higher priority
Default : 0 Present if  Confirmation Code  == 0x0 and Flow  Establishment Confirm for Token  Handover == 0x0 CS Specification Parameters 8 0-5: Reserved
16: Voice Codec  G.729A
17: Voice Codec AMR
18-55: Reserved Present if  Confirmation Code  == 0x0 and Flow  Establishment Confirm for Token  Handover == 0x0 MAC Header Type One Indicates whether AGMH or SPMH is  presented at the start of MAC PDUs  of the service flow .
0 : AGMH  ( Advanced Generic MAC Header )
One : SPMH  ( Short - Packet MAC header )
default value is  0. Present if  Confirmation Code  == 0x0 and Flow  Establishment Confirm for Token  Handover == 0x0 }

Next, referring to FIGS. 5 and 6, a method of additionally setting an FID in a unidirectional multicast connection will be described.

5 is a diagram illustrating a token transfer procedure in a one-way multicast connection according to an embodiment of the present invention.

The token transfer procedure is a procedure to change the direction of data transmission and reception while using the radio resources allocated for unidirectional direct communication connection. The right to transmit a signal through a radio resource is called a token. The terminal with the token may transmit a signal. The token is owned by one terminal, and the other terminal receives a signal through a radio resource.

Referring to FIG. 5, a transmitting terminal having a token receives a plurality of token information through an Advanced Air Interface-Direct Communication-Token-Advertisement (AAI-DC-TKN-ADV) message for token notification. Announce to the terminal (S510), through which it is known that the token is available.

The terminal that wants to have a token among the plurality of receiving terminals transmits an Advanced Air Interface Direct Communication -Token-Request (AAI-DC-TKN-REQ) message requesting a token to the transmitting terminal (S520). A direct communication token response (Advanced Air Interface Direct Communication-Token-Response, AAI-DC-TKN-RSP) message is received from the transmitting terminal (S530). In this case, the receiving terminal that wants to have a token may use a slot other than the slot in which the AAI-DC-TKN-ADV message is transmitted. That is, a procedure for requesting a token through a slot other than slot 1 in which a unidirectional multicast connection is established may be performed in a unidirectional one-to-one procedure. To this end, a receiving terminal wishing to have a token transmits a direct communication token request (AAI-DC-TKN-REQ) message through the data area of the RTS and a direct communication token response (AAI-DC-TKN) through the data area of the CTS. -RSP) message can be received.

At this time, the transmitting terminal determines the receiving terminal to which the token is to be delivered, and receives a plurality of token information through an Advanced Air Interface Direct Communication-Token-Handover (AAI-DC-TKN-HO) message indicating the token transfer. Notification to the terminal (S540), through which the token transfer procedure is completed.

Subsequently, the terminal acquiring the token (meaning a terminal selected from a plurality of receiving terminals) receives a direct communication link establishment instruction (Advanced Air Interface-Direct Communication-Link Establishment-Command, AAI-DC-LEST-CMD) message through a dedicated channel. Proceed to the procedure for establishing a multicast connection by transmitting to a plurality of receiving terminals (S550). When this procedure is performed continuously in a synchronization message, the terminal acquiring the token transmits a channel preamble (Ded-CH Preamble) through a dedicated channel and subsequently direct communication link establishment instruction (AAI-DC-LEST-CMD). Send a message to a plurality of receiving terminals. At this time, the direct communication link establishment instruction (AAI-DC-LEST-CMD) message is a broadcast type direct air RTS (Advanced Air Interface-Direct Communication-Request to Send, AAI-RTS) message (including DCGID) which proceeds with channel occupancy. Is sent with. Through such a procedure for establishing a multicast connection, a terminal (including a newly established terminal) without multicast connection information may join the multicast group. Meanwhile, in the AAI-DC-LEST-CMD message, a flow ID (FID) assigned by the terminal acquiring the token is set, and the terminal acquiring the token is determined by the terminal acquiring the token. Multicast connection using the assigned FID.

Meanwhile, in the above embodiment of the present invention, a receiving terminal that wants to have a token adds flow ID (FID) information to be set in addition to a direct communication token request (AAI-DC-TKN-REQ) message. That is, as shown in the underlined portion of Table 3 below, the direct communication token request (AAI-DC-TKN-REQ) message includes a field for setting a flow to be additionally set by a receiving terminal wanting to have a token. This added flow is used by the receiving terminal to acquire future tokens to process the traffic.

Table 3 below shows the description of the Direct Communication Token Request (AAI-DC-TKN-REQ) message field described above and the Direct Communication Token Request (AAI-DC-TKN-REQ) as shown in the underlined portion of Table 3. The message contains a field indicating the added flow.

Field Size  ( bits ) Value Of Description Condition Direct Mode Zone Type 2 Direct mode zone type of a recommended DCH
0x0: Common direct mode zone (CAAI-DCZ)
0x1: Common direct mode zone extended (CAAI-DCZ-E)
0x2: Cell specific direct mode zone (CSAAI-DCZ)
0x3 to 0xF: Reserved . DCH Number 4 Indicates a number of dedicated channel with DCH Number. For  (i = 0; i <N_Flow_Est; i ++) { N_ Flow _ Est is the number of flows on which the  sender of this message sends MAC PDUs .
Range  [0..1] FID 4 Flow identifier assigned by the source of  packets on the flow Traffic Priority 3 0 to  7: Higher numbers indicate higher priority
Default : 0 CS Specification Parameters 8 0-5: Reserved
16: Voice Codec  G.729A
17: Voice Codec AMR
18-55: Reserved MAC Header Type One Indicates whether AGMH or SPMH is presented at  the start of MAC PDUs of the service flow .
0 : AGMH  ( Advanced Generic MAC Header )
One : SPMH  ( Short - Packet MAC header )
default value is  0. }

As described above, a receiving terminal newly obtaining a token (hereinafter referred to as a 'token obtaining terminal') establishes a one-way multicast connection to a new receiving terminal.

6 is a diagram illustrating a link establishment procedure when a token acquiring terminal according to an embodiment of the present invention is one-way multicast connection.

Referring to FIG. 6, the token acquiring terminal transmits a preamble to a plurality of receiving terminals (S610), transmits an RTS, and directs a direct communication link establishment command through an RTS data area. Multicast the AAI-DC-LEST-CMD) message (S620). At this time, the token acquiring terminal includes the FID additionally set in FIG. 5 in the direct communication link establishment indication (AAI-DC-LEST-CMD) message, and the plurality of receiving terminals receiving the FID is allocated by the token acquiring terminal. Use for multicast connections. That is, the token acquiring terminal connects unidirectional multicast using the additionally set FID, so that a receiving terminal that does not previously have multicast connection information can join the multicast group.

Through such a procedure, the token acquisition terminal may complete a new resource allocation procedure and link setting procedure between receiving terminals.

Next, referring to FIGS. 7 to 9, a method of additionally setting an FID during unidirectional unicast connection and unicast relay connection will be described.

7 is a diagram illustrating an environment in which a terminal relays a direct communication relay link.

Referring to FIG. 7, the relay terminal 100 has a direct communication link (channel 1 of slot 1) established in relation to the transmitting terminal 200 and another direct communication link (slot 2) in relation to the receiving terminal 300. Channel) is set. The relay terminal 100 may be located in an area in which both the coverage A of the transmitting terminal 200 and the coverage B of the receiving terminal 300 are located. The relay terminal 100 receives data transmitted by the transmitting terminal 200 through a direct communication link and transmits the data to the receiving terminal 300 through another direct communication link.

8 is a diagram illustrating a procedure of acquiring relay information according to an embodiment of the present invention.

Referring to FIG. 8, the transmitting terminal transmits an advanced air interface direct communication-relay request (AAI-DC-RELAY-REQ) message requesting relay information to the relay terminal (S810). The AAI transmits a direct communication relay request (AAI-DC-RELAY-REQ) message to the receiving terminal (S820).

The receiving terminal transmits an Advanced Air Interface Direct Communication-Relay-Response (AAI-DC-RELAY-RSP) message to the relay terminal in response (S830), and the relay terminal transmits a direct communication relay response message to the transmitting terminal. Transmit (S840).

This procedure completes the relay information request and acquisition process.

9 is a diagram illustrating a procedure of acquiring relay information according to another embodiment of the present invention.

Referring to FIG. 9, the transmitting terminal transmits a preamble to the relay terminal (S910), and transmits a direct communication relay request (AAI-DC-RELAY-REQ) message requesting relay information through the RTS data (S920). . In this regard, the relay terminal transmits a preamble to the transmitting terminal that has transmitted the direct communication relay request (AAI-DC-RELAY-REQ) message (S930), and direct communication relay response (AAI-DC-RELAY-) through the CTS message. RSP) transmits a message (S940).

Meanwhile, in the embodiment of the present invention, the direct communication relay request (AAI-DC-RELAY-REQ) message described with reference to FIG. Field, and the AAI-DC-RELAY-RSP message includes a "Flow Establishment Confirm for Token Handover" field as shown in the underlined portion of Table 5 below. Through such a field, token transfer function negotiation takes place. The direct communication relay response (AAI-DC-RELAY-RSP) message further includes a field indicating an additional FID setting for supporting token handover, as shown in the underlined portion of Table 5 below. That is, the receiving terminal or the relay terminal adds a field for setting an additional flow (flow to be used by the receiving terminal or the relay terminal) to the AAI-DC-RELAY-RSP message, and through this, the receiving terminal or the relay terminal After acquiring this future token, the flow used to process the traffic is set.

Table 4 shows AAI-DC-RELAY-REQ message field descriptions, and Table 5 shows AAI-DC-RELAY-RSP message field descriptions.

Field Size  ( bits ) Value Of Description Condition Link Change Count 4 The change count of this transaction assigned by the sender. If new transaction is started, Link Change Count is incremented by one (modulo 16) by the sender. Shall always be present For (i = 0; i <N_Flow_Est; i ++) { N_Flow_Est is the number of flows on which the sender of this message sends MAC PDUs.
Range [0..1] FID 4 Flow identifier assigned by the sink of packets on the flow Traffic priority 3 0 to 7: Higher numbers indicate higher priority
Default: 0 CS Specification Parameters 8 0-15: Reserved
16: Voice Codec G.729A
17: Voice Codec AMR
18-255: Reserved MAC Header Type One Indicates whether AGMH or SPMH is presented at the start of MAC PDUs of the service flow.
0: AGMH (Advanced Generic MAC Header)
1: SPMH (Short-Packet MAC header)
default value is 0. } Target DCTID or DCGID 24 Indicates a receiving HR-MS (Group) address. Flow Establishment  Request for Token Handover 4 Indicates that the sending HR - MS  requests the receiving HR - MS to  establish flows and send MAC PDUs on  the flows
0x0: Request to establish flow for  token handover
0x1: Not allowed
0x2 to  0 xF : Reserved . Present if Target  DCTID exists

Field Size  ( bits ) Value Of Description Condition Link Change Count 4 Link Change Count from the corresponding AAI-DCRELAY-REQ Shall always be present Confirmation Code 4 Zero indicates the request was successful. Nonzero indicates failure.
0x0: accept
0x1: reject with a recommended DCH
0x2: wait next response message
0x3 to 0xF: reserved Shall always be present Direct Mode Zone Type 2 Direct mode zone type of a recommended DCH
0x0: Common direct mode zone (CAAI-DCZ)
0x1: Common direct mode zone extended (CAAI-DCZ-E)
0x2: Cell specific direct mode zone (CSAAI-DCZ)
0x3 to 0xF: Reserved . Present if Confirmation Code == 0x1 DCH Number 6 Recommended DCH number on zone of Direct Mode Zone Type Present if Confirmation Code == 0x1 Flow Establishment  Confirm for Token Handover One Zero indicates that the sending  HR-MS of this message confirms flow establishment .
0 : Confirm flow establishment for  token handover
One : Not allowed Present if  Confirmation Code  == 0x0 and the  sending HR - MS of  this message  receives the ? low  Establishment Confirm for Token  Handover? ield For  (i = 0; i <N_Flow_Est; i ++) { N_ Flow _ Est is the number of flows on  which the sender of this message  sends MAC PDUs .
Range  [0..1] Present if  Confirmation Code  == 0x0 and Flow  Establishment Confirm for Token  Handover == 0x0 FID 4 Flow identifier assigned by the  source of packets on the flow Present if  Confirmation Code  == 0x0 and Flow  Establishment Confirm for Token  Handover == 0x0 Traffic Priority 3 0 to  7: Higher numbers indicate  higher priority
Default : 0 Present if  Confirmation Code  == 0x0 and Flow  Establishment Confirm for Token  Handover == 0x0 CS Specification Parameters 8 0-5: Reserved
16: Voice Codec  G.729A
17: Voice Codec AMR
18-55: Reserved Present if  Confirmation Code  == 0x0 and Flow  Establishment Confirm for Token  Handover == 0x0 MAC Header Type One Indicates whether AGMH or SPMH is  presented at the start of MAC PDUs  of the service flow .
0 : AGMH  ( Advanced Generic MAC Header )
One : SPMH  ( Short - Packet MAC header )
default value is  0. Present if  Confirmation Code  == 0x0 and Flow  Establishment Confirm for Token  Handover == 0x0 }

Next, referring to FIGS. 10 to 12, a method of additionally setting an FID in a unidirectional unicast connection and a multicast relay connection will be described.

FIG. 10 is a diagram illustrating an environment when a terminal is unidirectional unicast connection and multicast relay connection. FIG.

Referring to FIG. 10, when the transmitting terminal 200 transmits data to the relay terminal 100, the relay terminal 100 broadcasts or receives data received from the transmitting terminal 200 to the plurality of receiving terminals 300. Multicast. However, the present invention is not limited thereto, and a broadcast or multicast environment may be set between the transmitting terminal and the relay terminal.

11 is a diagram illustrating a procedure for establishing a one-way unicast connection and a multicast relay connection according to an embodiment of the present invention.

Referring to FIG. 11, a transmitting terminal transmits a direct communication relay request (AAI-DC-RELAY-REQ) message to a relay terminal (S1110), and the relay terminal directs a direct communication link establishment instruction to a plurality of receiving terminals (AAI-DC). -LEST-CMD) is transmitted (S1120). The relay terminal transmits a direct communication relay response (AAI-DC-RELAY-RSP) message to the transmitting terminal (S1130). Through this procedure, a unidirectional unicast connection is established between the transmitting terminal and the relay terminal, and a multicast connection is established between the relay terminal and the plurality of receiving terminals.

12 is a view showing a token management procedure of the relay terminal according to an embodiment of the present invention.

Referring to FIG. 12, when the transmitting terminal intends to return a token, the transmitting terminal transmits a direct communication token handover (AAI-DC-TKN-HO) message informing the relay terminal of the token transfer (S1210). Then, the relay terminal continuously transmits a direct communication token broadcast (AAI-DC-TKN-ADV) message to announce that the token is available to the plurality of receiving terminals (S1220). In this case, the slot between the transmitting terminal and the receiving terminal and the slot between the relay terminal and the receiving terminal may be different.

Thereafter, the receiving terminal that wants to have a token exchanges a direct communication token request / response (AAI-DC-TKN-REQ / RSP) message with the relay terminal (S1230, S1240). Transmit a direct communication token request (AAI-DC-TKN-REQ) message to the relay terminal (S1230), and receives a direct communication token response (AAI-DC-TKN-RSP) message from the relay terminal in response (S1240). ). On the other hand, the relay terminal that receives the direct communication token request (AAI-DC-TKN-REQ) message from the receiving terminal (receiving terminal that wants to have a token), if the decision to transfer the token direct communication token handover ( AAI-DC-TKN-HO) message is transmitted to a plurality of receiving terminals (S1250), through which the token management procedure is completed. Thereafter, the terminal receiving the token transmits data to the relay terminal and transmits the relay terminal to other terminals. Here, the relay terminal multicasts a direct communication link establishment indication (AAI-DC-LEST-CMD) message in order to newly establish a multicast connection (S1260).

Meanwhile, in an embodiment of the present invention, a receiving terminal that wants to have a token adds flow ID (FID) information to be additionally set in an AAI-DC-TKN-REQ message. That is, the AAI-DC-TKN-REQ message includes a field for setting a flow to be additionally set by a receiving terminal that wants to have a token. Used to handle this traffic. The direct communication token request (AAI-DC-TKN-REQ) message is shown in Table 3.

As described above, whenever the target is changed in the multicast relay connection, the relay terminal performs the multicast relay connection setup. This procedure is a method in which the multicast connection setup is performed without changing the relay terminal.

13 is a diagram illustrating a link establishment procedure when a relay terminal connects to a one-way multicast according to an embodiment of the present invention.

Referring to FIG. 13, the relay terminal transmits a preamble to a plurality of receiving terminals (S1310), transmits an RTS, and multi-direct communication link establishment indication (AAI-DC-LEST-CMD) message through the RTS data area. To cast (S1320). At this time, the relay terminal includes the FID additionally set in FIG. 12 in the direct communication link establishment indication (AAI-DC-LEST-CMD) message, and the plurality of receiving terminals receive the multicast using the additionally set FID. Used to connect. That is, the relay terminal connects unidirectional multicast using the additionally set FID, so that a receiving terminal that does not previously have multicast connection information can join the multicast group.

Through such a procedure, the relay terminal may newly complete a resource allocation procedure and a link setting procedure among a plurality of receiving terminals.

Next, a signaling method for dynamically maintaining a multicast connection group will be described. Although a call group belonging to a multicast connection has a dynamically variable characteristic, multicast connection information is transmitted only when a multicast connection is established, and thus may not support dynamic characteristics of the call group. In order to compensate for this, embodiments of the present invention support the dynamic variability of the multicast talkgroup by repeatedly performing the multicast connection procedure.

14 is a diagram illustrating a link establishment procedure in unidirectional multicast connection for dynamically maintaining a multicast connection group according to an embodiment of the present invention.

As shown in FIG. 14, the transmitting terminal transmits a MAC header S1410, a preamble 1420, and an RTS to a plurality of receiving terminals, and direct communication link establishment instruction (AAI-DC) through the RTS data area. -LEST-CMD) multicasts the message (S1430). Ranging notifications are set in the MAC header.

On the other hand, as shown in Figure 14, the transmitting terminal according to an embodiment of the present invention three frames composed of a MAC header (MAC header), preamble, direct communication link establishment indication (AAI-DC-LEST-CMD) message Send it repeatedly. That is, the transmitting terminal repeatedly transmits a direct communication link establishment indication (AAI-DC-LEST-CMD) message to dynamically maintain the multicast connection group, and a transmitting period may be selected by the transmitting terminal.

Next, referring to FIG. 15, a signaling method for releasing a call when detecting whether the receiving terminal is within a communication distance and deviating is described.

15 is a diagram illustrating a method for detecting and releasing link loss in unidirectional unicast direct communication according to an embodiment of the present invention.

While transmitting traffic between the transmitting terminal and the receiving terminal, the transmitting terminal detects a link loss when there is no signal on the auxiliary channel in the unidirectional unicast connection (S1510). In this case, the method of detecting the link loss by the transmitting terminal determines that there is no response to the auxiliary channel more than a predetermined number of times. If there is no response in the auxiliary channel, the unassigned auxiliary channel code reception or auxiliary channel signal may be lower than the clear channel threshold.

When the transmitting terminal detects a link loss, an advanced air interface direct communication link release instruction (AAI-DC-LREL-CMD) message is transmitted to the receiving terminal to release the direct communication link (S1520). ). The transmitting terminal receives the response (ACK) from the receiving terminal and releases the link. Here, the link release command code field of the AAI-DC-LREL-CMD message may be set to a link loss (0x01).

As shown in FIG. 15, when there is no signal response to the auxiliary channel in the unidirectional multicast connection as well as the unidirectional unicast connection, it may be determined as a link loss. That is, in the unidirectional multicast connection, when the auxiliary channel signal is lower than the clear channel threshold, it may be determined as a link loss. When the transmitting terminal detects the link loss as described above, the direct communication link release indication (AAI-DC-LREL-CMD) message may be transmitted to the plurality of receiving terminals, and the link may be released without receiving a response. In this case, the link release command code field of the AAI-DC-LREL-CMD message may be set to a link loss (0x01).

Lastly, referring to FIGS. 16 and 17, a signaling method of operating a plurality of dedicated channels in one link will be described. That is, a procedure for deleting a dedicated channel will be described to support a function of allocating a plurality of dedicated channels.

16 is a diagram illustrating a method for releasing a dedicated resource channel in unidirectional unicast direct communication according to an embodiment of the present invention.

First, it is assumed that a plurality of dedicated channels are used for a unidirectional direct communication link between a transmitting terminal and a receiving terminal.

The transmitting terminal receives the status of the channel transmitted from the receiving terminal (S1610), and determines a dedicated channel to release among a plurality of dedicated channels (S1620). When the transmitting terminal determines a dedicated channel to release among a plurality of dedicated channels, an instruction for changing a direct communication resource including a field for identifying a resource of the dedicated channel to be released (Advanced Air Interface Direct Communication-Resource Change-Command, AAI-DC- The RCHG-CMD) message is transmitted to the receiving terminal (S1630). As indicated by the underlined portion of Table 6 below, the AAI-DC-RCHG-CMD message includes a field for identifying a resource of a dedicated channel to be released.

Although FIG. 16 illustrates a unidirectional unicast direct communication connection, the method may be applied to a unidirectional multicast direct communication connection.

Table 6 below shows a description of the AAI-DC-RCHG-CMD message field.

Field Size  ( bits ) Value Of Description Condition For (i = 0; i <N_DCH; i ++) { N_ DCH is the number of DCHs which are changed to new DCHs Old Direct Mode Zone Type 2 Direct mode zone type for old DCH
0x0: Common direct mode zone (CAAI-DCZ)
0x1: Common direct mode zone extended (CAAI-DCZ-E)
0x2: Cell specific direct mode zone (CSAAI-DCZ)
0x3: Reserved . Old DCH Number 4 Indicates old DCH number. New Direct Mode Zone Type 2 Direct mode zone type for new DCH
0x0: Common direct mode zone (CAAI-DCZ)
0x1: Common direct mode zone extended (CAAI-DCZ-E)
0x2: Cell specific direct mode zone (CSAAI-DCZ)
0x3: Reserved . New DCH Number 4 Indicates new DCH number. } For  (i = 0; i <N_DCH_Rel; i ++) { N_ DCH _ Rel is the number of DCHs which  are released from TDC communication Direct Mode Zone Type 2 Direct mode zone type for release
0x0: Common direct mode zone  ( CAAI - DCZ )
0x1: Common direct mode zone extended  ( CAAI - DCZ -E)
0x2: Cell specific direct mode zone  ( CSAAI - DCZ )
0x3: Reserved . DCH Number 4 Indicates DCH number for release }

17 is a diagram illustrating a method of releasing a dedicated channel in a bidirectional unicast direct communication link according to an embodiment of the present invention.

First, it is assumed that a plurality of dedicated channels are operated in a bidirectional direct communication link between a transmitting terminal and a receiving terminal.

The transmitting terminal receives the status of the transmitted channel from the receiving terminal (S1710), and determines a dedicated channel to release among the plurality of dedicated channels (S1720). At this time, when the transmitting terminal determines a dedicated channel to release among a plurality of dedicated channels, a direct communication resource change request including a field for identifying a resource of the dedicated channel to release (Advanced Air Interface Direct Communication-Resource Change-Request, AAI- The DC-RCHG-REQ) message is transmitted to the receiving terminal through slot 1 (S1730). As shown in the underlined portion of Table 7, the AAI-DC-RCHG-REQ message includes a field for identifying a resource of a dedicated channel to be released.

Table 7 shows a description of the AAI-DC-RCHG-REQ message field.

Field Size  ( bits ) Value Of Description Condition For (i = 0; i <N_DCH; i ++) { N_DCH is the number of dedicated channels Old Direct Mode Zone Type 2 Direct mode zone type for old DCH
0x0: Common direct mode zone (CAAI-DCZ)
0x1: Common direct mode zone extended (CAAI-DCZ-E)
0x2: Cell specific direct mode zone (CSAAI-DCZ)
0x3 to 0xF: Reserved . Old DCH Number 4 Indicates old DCH number. New Direct Mode Zone Type 2 Direct mode zone type for new DCH
0x0: Common direct mode zone (CAAI-DCZ)
0x1: Common direct mode zone extended (CAAI-DCZ-E)
0x2: Cell specific direct mode zone (CSAAI-DCZ)
0x3: Reserved . New DCH Number 4 Indicates new DCH number. } For (i = 0; i <N_DCH_NI; i ++) { N_DCH_NI is the number of recommended dedicated channels for candidates of new DCHs Present if 0 <N_DCH_NI Direct Mode Zone Type 2 Direct mode zone type of a recommended DCH
0x0: Common direct mode zone (CAAI-DCZ)
0x1: Common direct mode zone extended (CAAI-DCZ-E)
0x2: Cell specific direct mode zone (CSAAI-DCZ)
0x3: Reserved . DCH Number 6 DCH number of a candidate Noise and Interference Level Mean 8 Noise and Interference mean. This is noise plus interference power level that is divided by the number of subcarriers in the frequency domain and averaged over the dedicated channel.
-134 dBm to -30 dBm in units of 1 dB.
-134 dBm is encoded as 0x00,
-30 dB is encoded as 0x69,
0x69 to 0xFF is reserved . Noise and Interference Level Variance 4 Noise and Interference variance.
0 dB to 15 dB in units of 1 dB. } For  (i = 0; i <N_ DCH _ Rel ; i ++) { N_ DCH _ Rel is the number of DCHs which are  released from TDC communication Direct Mode Zone Type 2 Direct mode zone type for release
0x0: Common direct mode zone  ( CAAI - DCZ )
0x1: Common direct mode zone extended  ( CAAI - DCZ -E)
0x2: Cell specific direct mode zone  ( CSAAI - DCZ )
0x3: Reserved . DCH Number 4 Indicates DCH number for release }

Meanwhile, the receiving terminal, not the transmitting terminal, may determine a dedicated channel to release and request it to the transmitting terminal. As shown in FIG. 17, the receiving terminal may determine a dedicated channel to release after measuring a channel state (S1740). When the receiving terminal determines a dedicated channel to release among a plurality of dedicated channels, a direct communication resource change response including a field for identifying a resource of the dedicated channel to be released (Advanced Air Interface Direct Communication-Resource Change-Request, AAI-DC- The RCHG-RSP) message is transmitted to the transmitting terminal through slot 2 (S1750). As indicated by the underlined portion of Table 8 below, the AAI-DC-RCHG-RSP message includes a field for identifying a resource of a dedicated channel to be released.

Table 8 shows a description of the AAI-DC-RCHG-RSP message field.

Field Size  ( bits ) Value Of Description Condition Confirmation Code 4 Zero indicates the request was successful. Nonzero indicates failure.
0x0: accept with new mapping of DCHs
0x1: reject (continue to use current DCHs)
0x2 to 0xF: reserved Shall always be present For (i = 0; i <N_DCH; i ++) { N_ DCH is the number of DCHs which are changed to new DCHs Present if Confirmation Code == 0x0 Old Direct Mode Zone Type 2 Direct mode zone type for old DCH
0x0: Common direct mode zone (CAAI-DCZ)
0x1: Common direct mode zone extended (CAAI-DCZ-E)
0x2: Cell specific direct mode zone (CSAAI-DCZ)
0x3: Reserved . Old DCH Number 4 Indicates old DCH number. New Direct Mode Zone Type 2 Direct mode zone type for new DCH
0x0: Common direct mode zone (CAAI-DCZ)
0x1: Common direct mode zone extended (CAAI-DCZ-E)
0x2: Cell specific direct mode zone (CSAAI-DCZ)
0x3: Reserved . New DCH Number 4 Indicates new DCH number. } For  (i = 0; i <N_DCH_Rel; i ++) { N_ DCH _ Rel is the number of DCHs which  are released from TDC communication Direct Mode Zone Type 2 Direct mode zone type for release
0x0: Common direct mode zone  ( CAAI - DCZ )
0x1: Common direct mode zone extended  ( CAAI - DCZ -E)
0x2: Cell specific direct mode zone  ( CSAAI - DCZ )
0x3: Reserved . DCH Number 4 Indicates DCH number for release }

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

Claims (20)

In the signaling method of a first terminal for direct communication between terminals,
Transmitting a first link establishment request message for establishing a direct communication link to a second terminal, and
Receiving, from the second terminal, a first link establishment response message for establishing a direct communication link,
The first link establishment response message includes a first field indicating a flow to be used by the second terminal. The method of claim 1,
The first link establishment request message further includes a second field indicating a flow establishment request for token transfer. The method of claim 2,
The first link establishment response message includes a field indicating a flow establishment confirmation (Confirm) for token transfer. The method of claim 1,
The first link establishment request message is transmitted through a request to send data portion,
And the first link establishment response message is transmitted through a Clear to Send data portion. The method of claim 1,
Detecting a loss of the direct communication link, and
If the loss of the direct communication link is detected, further comprising releasing the direct communication link. The method of claim 5,
The detecting step,
And determining that the direct communication link is lost when no signal is received over a predetermined number of channels among channels established between the first terminal and the second terminal. The method of claim 5,
The releasing step,
And sending a release link indication message to the second terminal to release the direct communication link. The method of claim 1,
And when the direct communication link is operated with a plurality of dedicated channels, releasing at least one dedicated channel of the plurality of dedicated channels. The method of claim 8,
Releasing the at least one dedicated channel,
Receiving a status of the plurality of dedicated channels from a second terminal at all times and determining a dedicated channel to release among the plurality of dedicated channels; and
And transmitting a resource change indication message including a field for identifying a resource for the dedicated channel to be released to the second terminal. In the signaling method of a first terminal for direct communication between terminals,
Transmitting a token broadcast message for token notification to a plurality of second terminals;
Receiving a token request message from a desired third terminal having a token among the plurality of second terminals, and
Transmitting a token response message that is a response to the token request message to the third terminal,
The token request message includes a first field indicating a flow to be used by the third terminal. The method of claim 10,
The flow is a signaling method used in the multicast connection of the third terminal. The method of claim 10,
And transmitting a token handover message informing of token transfer to the plurality of second terminals. In the signaling method of a first terminal for direct communication between terminals,
Transmitting a MAC header to a plurality of second terminals,
Transmitting a preamble to the plurality of second terminals;
Repeatedly transmitting a link establishment indication message for establishing a direct communication link through the request to send data portion to the plurality of second terminals; and
Generating, by the plurality of second terminals, a response message including a first field indicating a flow to be used by the plurality of second terminals. The method of claim 13,
Detecting a loss of the direct communication link, and
If the loss of the direct communication link is detected, further comprising releasing the direct communication link. The method of claim 14,
The detecting step,
A signaling method comprising determining that the direct communication link is lost when a signal transmitted to an auxiliary channel among channels established between the first terminal and the plurality of second terminals is lower than a clear channel threshold; . In the signaling method of a relay terminal for relaying direct communication between a first terminal and a second terminal,
Receiving a relay request message for requesting relay information from the first terminal, and
Transmitting a relay response message, which is a response to the relay request message, to the first terminal;
The relaying response message includes a field indicating a flow to be used by the second terminal. The method of claim 16,
Transmitting the relay request message to the second terminal, and
And receiving, from the second terminal, the relay response message including the field. The method of claim 16,
The relay request message includes a field indicating a flow establishment request for token transfer,
The relay response message further includes a field indicating a flow establishment confirmation (Confirm) for token transfer. In the signaling method of a relay terminal for relaying direct communication between a first terminal and a plurality of second terminals,
Receiving a token handover message for token transfer from the first terminal;
Transmitting a token broadcast message for token notification to the plurality of second terminals;
Receiving a token request message from a third terminal that wants to have a token among the plurality of second terminals, and
Transmitting a token response message that is a response to the token request message to the plurality of third terminals;
The token request message includes a field indicating a flow to be used by the third terminal. The method of claim 19,
And transmitting a link establishment indication message including the flow to the plurality of second terminals and the third terminals.

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