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Method of Determining Resource Release Hang-Time and Resource Acquisition Timeout in a Broadband Push-To-Talk System

IP.com Disclosure Number: IPCOM000245873D
Original Publication Date: 2016-Apr-14
Included in the Prior Art Database: 2016-Apr-14
Document File: 4 page(s) / 26K

Publishing Venue

Motorola

Related People

Gilbert, Steve: INVENTOR

Abstract

A method is described which a Push-To-Talk (PTT) Call Controller may use to decide when to request termination of a Guaranteed Bit-Rate (GBR) bearer when the Call Controller is used in conjunction with a 3GPP LTE cellular radio system, or other similar system in which GBR bearers are used as a resource to carry the audio of the PTT voice call. The method helps to provide conversational continuity (such as low PTT delay) where it is most needed while also allowing efficient use of GBR resources.

A method is also described for determining an appropriate limit on the amount of time allowed to elapse for the establishment of GBR bearers before allowing a PTT call to start.

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Method of Determining Resource Release Hang-Time and Resource Acquisition Timeout in a Broadband Push-To-Talk System

By Stephen Gilbert

Motorola Solutions

 

ABSTRACT

A method is described which a Push-To-Talk (PTT) Call Controller may use to decide when to request termination of a Guaranteed Bit-Rate (GBR) bearer when the Call Controller is used in conjunction with a 3GPP LTE cellular radio system, or other similar system in which GBR bearers are used as a resource to carry the audio of the PTT voice call. The method helps to provide conversational continuity (such as low PTT delay) where it is most needed while also allowing efficient use of GBR resources.

A method is also described for determining an appropriate limit on the amount of time allowed to elapse for the establishment of GBR bearers before allowing a PTT call to start.

PROBLEM

When a PTT Call Controller is used in conjunction with a 3GPP LTE cellular radio system, the PTT Call Controller may request the establishment of a separate LTE unicast GBR bearer for each member of the talkgroup on which a one-to-many group call is being initiated. During the call, each of the GBR bearers is used as a virtual channel to convey voice packets to the corresponding mobile radio (User Equipment, or UE) which is used by a talkgroup member.

When the user who had been talking releases their PTT button at the end of the talkspurt, the Call Controller is notified and must decide when to deallocate the GBR bearer from each member of the talkgroup. (Note that a talkspurt is the voice content sent from a user during a single PTT press interval). If each GBR bearer is deallocated soon after PTT is released, then it is possible that one of the group members may press their PTT to initiate an additional talkspurt which is intended to be part of the same conversation, but which is instead delayed while the GBR bearers are reestablished for each talkgroup member. The termination and reestablishment of the GBR bearers causes additional signaling traffic load which would not have occurred if they had remained established. It is possible that the channel resources needed to reestablish some of the GBR bearers may not be available, which could delay the transmission of the talkspurt or prevent one or more of the talkgroup members from hearing part or all of the talkspurt. To avoid these problems (which can impede the verbal flow of a conversation) it is useful to delay the deallocation of the GBR bearer of each talkgroup member for some period of time (the “hang time”) in order to keep them available for use by a possible subsequent talkspurt within that talkgroup. However, as the hang time is lengthened, the amount of time during which the GBR bearer resources are allocated but are unused increases, thereby wasting more GBR capacity. This has the potential to increase the blocking or delay experienced by other PTT calls or other traffic which needs to use GBR bearers.

A related problem exists when a PTT butt...