Browse Prior Art Database

H.323 PROTOCPL EXTENSIONS TO IMPROVE WIRELESS OPERATION

IP.com Disclosure Number: IPCOM000004742D
Original Publication Date: 2001-Apr-25
Included in the Prior Art Database: 2001-Apr-25
Document File: 2 page(s) / 8K

Publishing Venue

Motorola

Related People

Tyrone Bekiares: AUTHOR [+2]

Abstract

H.323 PROTOCPL EXTENSIONS TO IMPROVE WIRELESS OPERATION

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This is the abbreviated version, containing approximately 53% of the total text.

H.323 PROTOCPL EXTENSIONS TO IMPROVE WIRELESS OPERATION

by Tyrone Bekiares and Donald Newberg

BACKGROUND

The H.323 protocol includes provisions for each PDU to be extended with vendor-specific non-standard data. Motorola has identified several PDU extensions which facilitate improved wireless operation of the protocol.

EXTENSIONS TO THE REGISTRATION REQUEST (RRQ) PDU

As part of a gatekeeper-controlled H.323 network, H.323 terminals must register with a network gatekeeper as they come online. The standard H.323 registration procedure allows terminals to only crudely classify themselves as an endpoint, a gatekeeper, a gateway, etc.

To ensure good quality of service in a wireless conferencing environment, RF resources should be explicitly allocated for any streaming media present within a given call. To facilitate this, the gatekeeper must know whether the endpoints involved in a call reside on wireless or wireline links. H.323, in its current revision, does not have the capability to transmit this information.

To additionally conserve RF resources, the endpoints should know a priori what types of capabilities other given endpoints support. This information is normally not transmitted until the call setup phase begins. Using the extension disclosed here, however, endpoints transmit their capabilities at registration time to the gatekeeper. This information is then correlated into a network directory which can be accessed by the clients through a web page or similar interface. This prevents endpoints from trying to setup a call with other endpoints who do not support a given call type (e.g. two-way audio and two-way video, no audio and one-way video, etc).

Additionally, the Gatekeeper may want to prevent endpoints from calling other endpoints who are already involved in the maximum number of calls they can support. Doing so limits the number of messages that need to be transmitted for a call request that will eventually be denied anyway.

This particular extension to H.323 is accomplished by extending the standard H.323 RegistrationRequest (RRQ) PDU with a non-standard data section. The layout of the non-standard data is shown in Figure 1.1.

EXTENSIONS TO THE REGISTRATION CONFIRM (RCF) PDU

H.323 defines a mechanism whereby terminals may send in "keep-alive" data to a system gatekeeper while they are involved in a call. The interval at which the Gatekeeper expects to receive unsolicited keep-alive messages is, under the current H.323 revision, transmitted in the AdmissionConfirm (ACF) PDU.

In a wireless environment with limited RF resources, the ability to quickly detect when a subscriber is out-of-range is paramount to system performance. Fortunately, the H.323 standard defines a mechanism whereby endpoints involved in calls must transmit unsolicited status reports to the gatekeeper every n seconds. Unfortunately, the period n is transmitted...