Method and system for interrupted floor recovery in push-to-talk over cellular network

The present invention relates to a system and method that provides a configuration for recovering an interrupted floor interrupted during a Media Control process.

The PoC (Push to talk over Cellular) service defines a variety of requirements that take into account the different PoC user groups and the nature of their participation in the PoC group. One of the unique features of PoC services is the definition of priorities in media control requirements. When a PoC user requests media using priority, the controlling PoC server checks the media request along with the priority.

Currently, the three priorities defined in the PoC service are normal user, high-priority user, and preemptive user. Normally, the PoC server grants media transmission rights in the order in which media requests arrive. When one or more regular PoC users generate media requests, the requests are queued in the order they arrive. When requesting the queue to wait for media transmission rights, high priority PoC users usually have a higher priority than PoC users. Therefore, a high-priority PoC user is queued and waits so that the transmission right is granted earlier than the normal PoC user's request even if the transmission right is requested later than the normal PoC user's request. If the queue is not supported, transmission rights are granted in the order in which media transmission rights are requested, regardless of whether they are regular users or high-priority PoC users. Users with the same priority do not have priority over other users with the same priority. In such a case, the request for the media transmission right is waited in the requested time order.

When a proof-of-concept PoC user requests a media transmission right (floor), the media transmission right is immediately granted regardless of whether another user, that is, a normal-priority or high-priority PoC user, is transmitting the media. Given. Therefore, as soon as the proof-of-concept user requests the media transmission right, the media transmission transmitted by the normal PoC user or the high priority PoC user is interrupted.

Figure 1 shows the media control procedure when a preemptive user requests media.

Referring to FIG. 1, PoC client B transmits media in a PoC session in steps 100-103. PoC client A, a proof-of-concept PoC user, has an urgent need to transmit media while receiving media from PoC client B, and in steps 104 and 105, the PoC server controls the media transmission right request message. To transmit to.

The control PoC server X (control) determines whether the PoC client B transmitting the media is a proof-of-concept PoC user. If PoC Client B is not a proof-of-concept PoC user, according to server policy, Control PoC Server X interrupts PoC Client B's media transmission by transmitting a stop talk burst message in steps 106 and 107. To do.

PoC client B transmits the last buffered media packet to control PoC server X in steps 108 and 109, and controls the Media Burst Complete message in steps 112 and 113. Send to X.

The control PoC server X forwards the last media packet received from PoC client B in steps 110 and 111, and sends a Media Burst Confirm message to PoC client A in steps 114 and 115.

Upon receiving this media transmission permission message, PoC client A notifies PoC user A that media transmission is possible. The PoC client A then begins transmitting media to the controlling PoC server in steps 116 and 117. In steps 120 and 121, the controlling PoC server sends the media to all other PoC clients participating in the PoC session, except for the transmitting PoC user. Before transmitting the media, the controlling PoC server transmits a Receiving Media burst message to other PoC clients to inform the proof-of-concept PoC user that the media is being transmitted.

<p> The prior art described above allows a proof-of-concept PoC user to interrupt an ongoing media transmission and transmit his or her own media, but provides a way to return media transmission rights to the interrupted PoC user. Absent. That is, a PoC user whose media transmission has been interrupted by a proof-of-concept PoC user will no longer be able to transmit media, and will request media transmission rights and wait at the last position in the queue to transmit media. Become. Thus, interrupting the PoC user's media transmission by an interrupt of the proof-of-concept PoC user can be a bad user experience from the PoC user's point of view. Such a characteristic may also be undesired by a proof-of-concept PoC user who seeks to temporarily revoke a media transmission right.</p><p> Therefore, in order to solve the above-mentioned problems of the prior art, an object of the present invention is to temporarily interrupt the ongoing media transmission by an authorized PoC user in the current PoC infrastructure to make important matters. Provide systems and methods that can inform and recover interrupted media transmissions.</p>

<p> In order to achieve the above object, the present invention is a priority priority recovery system for media transmission rights interrupted by a PoC user in a PoC (Push to talk over Cellular) system, and media transmission by the PoC user. When there is a request, the floor request message is transmitted to the PoC server, the media is transmitted when the response to the media transmission right request is received, and then the media transmission completion message is transmitted when the media transmission is completed. When a floor request message is received with the PoC client, a media transmission interruption message is transmitted to the PoC client currently transmitting media, and when a media transmission completion message is received from the PoC client, media transmission is interrupted. It is characterized by including a PoC server that transmits a media transmission permission message in order to resume the interrupted media transmission to the PoC client.</p><p> The present invention is also a method of interrupting media transmission by a specific PoC client participating in a PoC session in a PoC system, when media transmission is required while receiving media in the PoC session. The stage where the PoC client transmits the floor request message, and when the floor request message is received, the PoC server transmits the media transmission interruption message to the PoC client that is currently transmitting the media, and the PoC client requests the transmission of the media. When the response to the media transmission right request is transmitted to, the stage where the PoC client transmits the media when the response to the media transmission right request is received, and when the media transmission is completed, the PoC client completes the media transmission. At the stage of transmitting the message to the PoC server, and when the media transmission completion message is received, the PoC server transmits a media transmission permission message to inform the PoC client whose media transmission has been interrupted that the media transmission is possible. Provided is a method characterized by having a stage of.</p>

<p> In the present invention, when a specific client who participates in a PoC session requests a media transmission right from the PoC server during media transmission from another client, the PoC server mediates the client who currently has the media transmission right. The transmission interruption message is transmitted to transition to the interruption state, and the media transmission right is given to the client requesting the media transmission right. When the interrupt client completes the media transmission, the PoC server returns the media transmission right to the interrupted client. Therefore, there is an advantage that a PoC client currently authorized in the PoC infrastructure can interrupt an ongoing dialogue, and when this interrupt ends, the interrupted media can be recovered immediately without making an explicit media request. It also has the advantage that the PoC client with priority priority can naturally sustain the dialogue even if it carries out a proof-of-concept scenario that interrupts the ongoing dialogue.</p>

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the following description, if it is determined that a specific description of the related known function or configuration obscures the gist of the present invention, the detailed description thereof will be omitted.

The present invention provides that if a privileged PoC user interrupts media transmission by another PoC user currently in transit and transmits his or her own media, then the interrupted PoC user has the right to transmit media. The purpose is to bring back.

SIP (Session Initiation Protocol) or Extended SIP, which is an application hierarchy protocol for controlling Internet Multimedia Communication (IP technology), is basically a group PoC (Puch to talk over Cellular) call. It is used as a signaling protocol for setting. Real Time Protocol (RTP) and Real Time Control Protocol (RTCP) are used for the practical transmission of media and media-related information, respectively. In addition, since PoC is a half-duplex service in principle, the real-time control protocol is a media control method that allows only one PoC user to transmit media information at a time. Used as mechanism). Also, SDP (Session Description) Protocol) can be transmitted, including information about environment settings. The information about the environment settings defines the media information used in the configured session, the port number used for each media, the codec information, and the bandwidth. That is, audio, video, photographs, and text can be used as media in one PoC session. Therefore, the media transmission right includes an audio transmission right, that is, a voice transmission right. SIP and SDP are included in the INVITE message and transmitted to establish a PoC session.

First, in the present invention, it is assumed that the PoC user requests media transmission and transmits the media in the PoC session. In addition, the PoC system implements a queue for waiting for media transmission requests, and PoC users are given media transmission rights when their turn comes. The PoC system utilizes RTP and RTCP for media and media related signaling and media arbitration. Further, in the present invention, the media includes all media such as audio, video, text, video, and file, and particularly includes Talk realized by OMA PoC v1. Therefore, TB (Talk Burst) shown in the drawings of the present invention is regarded as a kind of media burst.

The present invention proposes new conditions for media arbitration procedures when priorities apply to media requirements. Therefore, a new media arbitration method is needed. FIG. 2 shows the flow of message signals between the PoC client and the PoC server according to the embodiment of the present invention.

A PoC session is configured between PoC Client A and PoC Client B. If there is another PoC user who has requested a media transmission right, the request for that media transmission right is queued in sequence.

PoC client B transmits media to PoC client A in steps 200-203. Group members who participate in a PoC session that includes PoC Client A receive the media transmitted by PoC Client B. If PoC User A wishes to transmit media to inform him of important matters, PoC User A using PoC Client A transmits a media transmission right request message to Control PoC Server X in steps 204 and 205. .. Here, PoC user A is assumed to be a user having one of the proof-of-concept priority and the interrupt priority.

Upon receiving a media transmission right request from PoC Client A through Participating PoC Server A, Control PoC Server X acknowledges that PoC User A wishes to suspend media transmission in progress. In steps 206 and 207, the controlling PoC server X sends a Media Burst (MB) Suspend message to PoC client B through participating PoC server B. This message includes the content that the media transmission right will be granted again after the media transmission of the proof-of-concept PoC user is completed. Upon receiving this media transmission interruption message, the PoC client B interrupts the media transmission according to the received request, and in steps 208 and 209, transmits a response message to the PoC server X that the media transmission interruption message has been received. Here, the processes of steps 108 to 113 shown in FIG. 1 are performed in the same manner, but the description thereof will be omitted.

The control PoC server X sends a media burst confirm message to PoC client A in steps 210 and 211. Upon receiving the media transmission permission message from the control PoC server X, PoC client A sends media to all clients participating in the PoC session, including PoC client B, in steps 212 to 215, and all clients participating in the PoC session. Receives media transmitted from PoC client A.

If the transmission to the media of the last packet is completed in steps 216 to 219, the PoC client A sends the media transmission completion message to the control PoC server in steps 220 and 221. Upon receiving the media transmission completion message of the primitive PoC client, the control PoC server X sends a media transmission permission message to PoC client B in steps 222 and 223 in order to recover the interrupted media transmission of the PoC client B.

Upon receiving the media transmission permission message, PoC client B recognizes that media transmission is possible, and in steps 224 to 227, sends the media to all clients participating in the PoC session, and all of the PoC sessions. The client receives the media transmitted from PoC client A.

On the other hand, in steps 206 and 207, the control PoC server X can transmit a stop media burst message or a media transmission interruption message as shown in FIG. 1 to notify that the media transmission of the PoC client has been interrupted. These two messages commonly include content requesting that media transmission be stopped and content that interrupted media transmission resumes after the media transmission of the proof-of-concept PoC user has finished.

FIG. 3 is a state diagram showing the media transmission right control procedure of the PoC client. The Talk Burst message shown in FIGS. 3 and 4 is an example of a message related to voice media among media burst messages. Therefore, the method according to the present invention can be applied equally to not only audio but also other media.

According to the procedure of the present invention, a new state is introduced to apply the interruption behavior to a PoC client whose media transmission is interrupted by the proof-of-concept PoC client. The new state according to the present invention has the property that when a media transmission interruption message is received from the control PoC server during media transmission, the PoC client stops the media transmission and its media transmission right request is placed in the first column of the queue. .. Therefore, in the new state, the PoC client whose media transmission is interrupted can no longer transmit the media and must receive the media from the proof-of-concept PoC client, after the media transmission of the proof-of-concept PoC client is finished. The PoC client resumes media transmission.

In the following, audio media will be described as an example in the media transmission right control procedure. Therefore, "media transmission" is described as a kind of media in a mixed manner.

Referring to FIGS. 2 and 3, first, the PoC client B transmits the media in the state 300, and when it receives the media transmission interruption message (TB_Suspend) indicated by 301, the media transmission interruption and the standby state (U: Suspend) are immediately received. It becomes state) 302 and operates as follows.

Upon receiving the media transmission interruption message from the control PoC server, the PoC client enters the media transmission interruption and standby state 302. The control PoC server queues the client's media for which media transmission has been interrupted so that it is transmitted after the proof-of-concept PoC user finishes media transmission.

If the PoC user suspends and waits for further media transmission, the PoC client grants the queued media transmission rights through a media transmission request cancellation (TB_Release) message, as indicated by 304. It can also be canceled. That is, the PoC client sends a media transmission request cancellation (TB_Release) message to remove the media transmission right request from the queue, thereby removing the media transmission right request from the media transmission interruption and standby state (U: has no permission) state. Transition to 305.

If the PoC client whose media transmission was interrupted wishes to resume media transmission, the control PoC server will MB_Grant to the PoC user whose media transmission was interrupted when the media transmission of the primitive PoC user is completed (in the figure). , TB_Grant) Re-grant media transmission rights by transmitting a message.

When the PoC client receives an MB_Grant (TB_Grant in the drawing) message such as 306 in media transmission interruption and standby state 302, the PoC client changes to media transmission ready (U: has Permission) state 300 and begins transmitting media. ..

Next, with reference to FIG. 4, the change in the state of the PoC user by controlling the PoC server in the embodiment of the present invention will be described.

The media transmission suspend and standby state (U: Suspend) 402 indicates that the media transmission of the PoC client is not permitted and the media must be received from the proof-of-concept PoC client. PoC user controls media transmission at 400 at the request of the proof-of-concept PoC user When the PoC server transmits a media transmission suspend (S: TB_Suspend or TB_Revoke) message, the PoC user suspends media transmission. And it becomes a standby state.

In the media transmission interruption and standby state (U: Suspended), as shown in 403, when the proof-of-concept PoC user's media is continuously transmitted to the PoC user through the control PoC server, the PoC user is in the media transmission interruption and standby state. To maintain.

When the control PoC server receives the media transmission request cancellation (R: TB_Release) message from the PoC client, it cancels the media transmission right request stored in the queue and puts the PoC user from the media transmission suspension and standby state (U: Suspended). Transition to state 405 without media transmission right and during other user media transmission'(U: Not Permitted AND TB_Taken).

When the PoC server receives a proof-of-concept PoC user media transmission request cancellation (R: TB_Release) message without receiving the R: TB_Release from the PoC user, the PoC server sends a media transmission permission (TB_Grant) message to the PoC user. .. The state of the PoC user who received this message changes from'U: Suspended'to'media transmission possible'(U: permitted) state.

The media transmission right request message transmitted by the proof-of-concept PoC client to the PoC server for the media transmission request will be described with reference to &lt;Table 1&gt; below.

The TBCP media transmission right request message is a message sent by the PoC client to the PoC server for media transmission. Through this message, the PoC server can determine which PoC user wants to transmit the media.

<tables num="1"><img file="JP2008546301A_D0001.tif" /></tables>

In the subtype field, the bit pattern 00000 is used for the media transmission right request message. The SSRC (Synchronization source) field contains the SSRC of the PoC client requesting permission for media transmission.

One or more option fields can be included in the media transmission right request message. The option field of each media transmission right request message contains three subfields.

The first subfield is the option ID subfield. The option ID subfield is an 8-bit option ID that indicates the selected option.

The second subfield is the optional length subfield. The option length subfield consists of a single byte that indicates the length of the option field in bytes. The value of the option length subfield is the same as the sum of the option ID, the option length, and the number of bytes in the option value subfield.

The third subfield is the option value subfield. The option value subfield has an integer number of bytes. The format and value of this subfield is option dependent.

A subclause, such as the following, defines a specific media transmission right request message option subfield.

For media transmission request priority levels, the media transmission request priority level option is included if the PoC client and PoC server agree to assist in queuing the media transmission request. However, in the case of priority priority, it is included in the options without supporting queuing.

The PoC client indicates that the PoC user wants the media transmission request to have a priority level other than normal priority, or the PoC client attempts to change the priority level of the media transmission request waiting in the queue. If so, include the priority level.

In this case, the option ID subfield has a value of 1. The option length subfield has a value of 3. The option value subfield contains one byte indicating the defined media transmission request priority level.

At this time, the defined media transmission request priority levels that can be included in the media transmission right request message are as follows.

1. normal priority 2. high priority 3. preemptive priority 4. interrupt priority The media transmission right request message indicating the interrupt priority contains a new value (ie, 4) in the option value field as described above. Instead of the new interrupt priority value, a new option ID subfield can be used to set the interrupt priority option in the media transmission right request message.

The above-described operation of the present invention can be realized by a media transmission right request message having a proof-of-concept priority and an operation of a PoC server. It should be noted that the present invention can obtain the same effect of the present invention through the message of the new interrupt priority.

A new TBCP message may be used to indicate to the PoC client that the media transmission is interrupted and that the interrupted media transmission request is waiting in the queue. Such a media transmission interruption message will be described with reference to &lt;Table 2&gt;.

<tables num="2"><img file="JP2008546301A_D0002.tif" /></tables>

Another unique bit pattern in the subtype field is utilized for media transmission interruption messages. In &lt;Table 2&gt; above, the XXXXX bit describes a unique number indicating the media transmission interruption message of the present invention.

The application-dependent data field contains a Reason code field for the PoC server performing the controlling PoC function to interrupt the media transmission of the PoC client. Also, since additional information can be included in the additional information field, the packet length can vary based on the value of the reason code field.

The SSRC field contains the SSRC of the PoC server that performs the control PoC function.

The media transmission interruption message is sent from the PoC server performing the control PoC function to the PoC client having the media transmission permission to indicate that the media transmission is interrupted.

As described above, the present invention is a method of modifying the media request procedure that interrupts the media transmission of a currently PoC user who is permitted to transmit media and induces the operation of the PoC server in order to transmit the media of the proof-of-concept PoC user. provide. This is done by introducing a new priority level or extending the primitive priority model.

Although the specific embodiments have been described above in the detailed description of the present invention, it is possible for a person having ordinary knowledge in the art to make various changes as long as the claims are not made. Is clear. Therefore, the scope of the present invention is not limited to the above-described embodiment, and should be determined based on the description of the scope of claims and equivalents thereof.

<figref num="1">It is a figure which shows the flow of the signal which shows the media transmission using a preemptive priority.</figref><figref num="2">It is a figure which shows the signal flow of the message between a PoC client and a PoC server by embodiment of this invention.</figref><figref num="3">It is a state transition diagram of the PoC client according to the embodiment of the present invention.</figref><figref num="4">It is a state transition diagram of the PoC server according to the embodiment of this invention.</figref>