Browse Prior Art Database

Application Server assisted Direct Mode Offload

IP.com Disclosure Number: IPCOM000247215D
Original Publication Date: 2016-Aug-17
Included in the Prior Art Database: 2016-Aug-17
Document File: 3 page(s) / 84K

Publishing Venue

Motorola

Related People

Madhusudan Pai: AUTHOR [+3]

Abstract

This paper describes a method for application server assisted direct mode push to talk calls. 3GPP ProSe [1] defines methods for LTE UEs to communicate in direct mode. This paper describes a method where PTT server is aware of a direct mode graph for each PTT group. This graph consists of UEs that are affiliated to the group which can communicate with each other either directly or through other UEs in the graph acting as a relay for this communication. When PTT Server determines that all call participants are in a connected graph for the PTT communication, PTT server instructs all the required devices in the graph to switch to direct mode, setup the communication session and on completion, resume network connected mode of operation. The communication may be for 1-1 or group PTT calls. This paper further describes how UEs that communicate over diverse technologies such as LMR direct mode can be included in the graph. Such UEs are bridged by converged (multi-mode) devices and/or collaborative devices (LMR and LTE device collaborating over a bluetooth link) that support both capabilities. This enables direct mode communication between LMR and LTE devices.

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Application Server assisted Direct Mode Offload

By Madhusudan Pai, Brundaban Sahoo, Tom Senese

Motorola Solutions

 

ABSTRACT

This paper describes a method for application server assisted direct mode push to talk calls.

3GPP ProSe [1] defines methods for LTE UEs to communicate in direct mode. This paper describes a method where PTT server is aware of a direct mode graph for each PTT group. This graph consists of UEs that are affiliated to the group which can communicate with each other either directly or through other UEs in the graph acting as a relay for this communication. When PTT Server determines that all call participants are in a connected graph for the PTT communication, PTT server instructs all the required devices in the graph to switch to direct mode, setup the communication session and on completion, resume network connected mode of operation. The communication may be for 1-1 or group PTT calls.

This paper further describes how UEs that communicate over diverse technologies such as LMR direct mode can be included in the graph. Such UEs are bridged by converged (multi-mode) devices and/or collaborative devices (LMR and LTE device collaborating over a bluetooth link) that support both capabilities. This enables direct mode communication between LMR and LTE devices.

PROBLEM

In an incident scene with dense population of LTE devices in small geographic area (e.g. single cell or few cells) unicast PTT service is inefficient. LTE broadcast/multicast based PTT service is proposed as part of 3GPP MC-PTT [2] standards. However, it may occur that under congestion, the network does not have sufficient broadcast/multi-cast bearers within a given cell. Hence there is a need for an off-network solution that enables PTT communication between participants.

3GPP ProSe [1] teaches how a UE discovers other UEs in direct mode vicinity. However, to move to an off-network mode for a group call, the UE must know that all other UEs affiliated to that group are available in direct mode vicinity. This information is not available at a UE.

On the contrary, A PTT server is aware of all UEs that are affiliated to a group. However, it is not aware of their direct mode capability. It is also unaware of the set of other UEs in a given UE’s direct mode vicinity.

Further, PTT Server is only aware of users served by it which are affiliated to the group. It is unaware of UEs in other networks (e.g. LMR or other broadband networks) that are also affiliated to the same group.

Finally, there may be scenarios where LTE users in 2 different cells are required to be in the same group call but there is no network coverage between these 2 cells (or eMBMS bearers available in these 2 cells due to higher priority PTT Calls). However, there may be converged (LMR & LTE) devices in these 2 cells that can talk to each other and therefore bridge LTE devices in these 2 cells as well as extend coverage to LMR devices in LMR range.

 

SOLUTION

This disclosure enables a network assisted m...