Browse Prior Art Database

DIVIDING ADVANCEMENT REQUESTS INTO PARTS

IP.com Disclosure Number: IPCOM000008342D
Original Publication Date: 1997-Sep-01
Included in the Prior Art Database: 2002-Jun-07
Document File: 3 page(s) / 137K

Publishing Venue

Motorola

Related People

Irina Veksler: AUTHOR [+2]

Abstract

Digital communication networks introduce outbound audio path. This scheme exploits that fact undesirable audio delay at various points along the that the assigned RF transmission slot remains transmission path. The Integrated Dispatch unchanged throughout the call. Therefore, a feedback Enhanced Network, or iDEN, utilizes a scheme, loop is used to minimize the difference between the known as Just In Time Audio (JITA), to minimize transmission time and the arrival of the outbound delay between the Transcoder (XCDR) and the audio packet from the Transcoder.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 50% of the total text.

Page 1 of 3

Technical Developments

DIVIDING ADVANCEMENT REQUESTS INTO PARTS

by lrina Veksler and Esteban Yepez, Ill

  Digital communication networks introduce outbound audio path. This scheme exploits that fact undesirable audio delay at various points along the that the assigned RF transmission slot remains transmission path. The Integrated Dispatch unchanged throughout the call. Therefore, a feedback Enhanced Network, or iDEN, utilizes a scheme, loop is used to minimize the difference between the known as Just In Time Audio (JITA), to minimize transmission time and the arrival of the outbound delay between the Transcoder (XCDR) and the audio packet from the Transcoder.

Enhanced Base Transceiver System (EBTS) on the

45 ms 15 ms #- . -

1

Fig. 1 An Example of Outbound Audio Delay

* Samples arriving from the Transcoder very early.

l

In this example, EBTS must hold the encoded samples for > 30 ms before transmitting * The EBTS will request the transcoder to send the samples earlier to reduce delay.

  This is accomplished by discarding or reusing a portion of the audio samples and setting a new timing reference to either delay or advance encod- ing. The subsequent outbound audio packets are received by the EBTS only milliseconds before they are transmitted in their assigned RF slot.

  A problem may arise whenever the XCDR receives an advancement request message from the EBTS. An advancement request requires the next

encode to occur earlier; it reduces the time available to encode the current frame by the amount of the advancement. Today's systems typically operate near full capacity. Therefore, reductions in processing time may create "overloading". This means that the required tasks were completed after they were required. "Overloading" is a serious problem in real-time systems. In an iDEN system, "overloading" results in lost audio packets, or audio gaps.

0 Mowrola, 1°C. ,997 175 Seprember 1997

[This page contains 15 pictures or other non-text objects]

Page 2 of 3

MOTVROLA Technical Developments

@

-45 ms

Fig. 2 Time Required to Encode Samples...