Dynamic build-out approach for use in packet voice systems

Details Dynamic build-out approach for use in packet voice systems Dynamic build-out approach for use in packet voice systems

1997-07-24

2001-08-28

Nguyen, Chau (Department: 2663)

Multiplex communications

Pathfinding or routing

Switching a message which includes an address header

C370S395430, C370S474000, C370S517000

Reexamination Certificate

active

06282196

ABSTRACT:

FIELD OF THE INVENTION
This invention relates generally to communications and, more particularly, to packet voice systems.
BACKGROUND OF THE INVENTION
Asynchronous transfer mode (ATM) networks carry fixed sized cells within the network irrespective of the applications being carried over ATM. At the network edge or at the end equipment, an ATM Adaptation Layer (AAL) maps the services offered by the ATM network to the services required by the application. There are a number of industry standards and proposed standards covering various AALs. In particular, “B-ISDN ATM Adaptation Layer Type 2 Specification,” draft Recommendation 1.363.2, November 1996, of ITU-T (herein referred to as AAL-2) provides for efficient ATM transport of small, delay-sensitive packets in such applications as packet voice systems.
In such a packet voice system, audio is transmitted in packets. Silences are suppressed (i.e., durations when signal power is below a predefined threshold). A sequence of audio packets, starting from the end of a silence duration to the beginning of the next silence duration, is referred to herein as a “talk-spurt.” A transmitter provides each packet with a sequence number. The range of sequence numbers is typically finite and repeats. For example, there may be eight sequence numbers,
0
-
7
. At the start of the first talk-spurt, the first transmitted voice packet includes the sequence number
0
. After the first eight packets are transmitted the sequence numbers begin to repeat, starting again at
0
. During silent intervals, the transmitter still counts sequence numbers such that the packet at the start of the next talk-spurt receives a sequence number just as if the silence interval had, instead, contained voice packets.
Upon receiving the first packet of a call, the receiver waits for an initial period of time, referred to herein as the “build-out” delay, before reconstructing and playing out the audio signal during a connection, or call. Once the build-out delay has passed, the receiver reconstructs the audio signal using the recovered sequence numbers to re-order received packets for the duration of the connection. Unfortunately, the use of sequence numbers, by themselves, and a single build-out delay for the entire call does not mitigate other anomalies present in packet voice systems due to packet delay and packet loss.
SUMMARY OF THE INVENTION
We have realized that it is desirable to use a dynamic build-out delay approach in a receiver during the duration of a call. In particular, the build-out delay is applied at least twice during the duration of the call.
In an embodiment of the invention, a packet voice system includes an AAL-2 and Service Specific Convergence Sublayer (SSCS) System. The receiver portion of the SSCS System recovers AAL-2 packets and plays back the compressed audio to a voice decoding element. In providing playback, the receiver applies the build-out delay at the start of each talk-spurt. The voice decoding element provides an uncompressed audio stream.
In another embodiment of the invention, the receiver portion of the SSCS System applies the build-out delay at the start of the each talk-spurt as a function of the length of the previous silence interval.


REFERENCES:
patent: 3578914 (1971-05-01), Simonelli
patent: 4920534 (1990-04-01), Adelmann et al.
patent: 5150358 (1992-09-01), Punj et al.
patent: 5255291 (1993-10-01), Holden et al.
patent: 5287347 (1994-02-01), Spanke
patent: 5396492 (1995-03-01), Lien
patent: 5606553 (1997-02-01), Christie et al.
patent: 5699369 (1997-12-01), Guha
patent: 5717691 (1998-02-01), Dighe et al.
patent: 5790538 (1998-08-01), Sugar
patent: 5831981 (1998-11-01), Tanimura et al.
patent: 5870397 (1999-02-01), Chauffour et al.
“An Algorithm for Playout of Packet Voice based on Adaptive Adjustment of Talkspurt Silence Periods” Pinto, et.al Local Computer Networks, 1999 LCN '99 Conference IEEE 1999 0-7695-0309-8/99 pp. 224-231, Aug. 1999.*
Adaptive Playout Mechanisms for Packetized Audio Applications in Wide-Area Networks, Ramachandran, et.al. INFOCOM '94 Networking for Global Communications 13'th proceedings IEEE 0743—166X/94 pp. 680-688 vol.2, Jun. 1994.*
Voice Communication Across the Internet: A Network Voice Terminal* Schulzrinne, Department of Electrical and cComputer Engineering University of Massachusetts, Amherst, MA 01003. Jul. 29, 1992.*
Modeling and ATM_Based Access Network for 3rd Generation Mobile Communication Networks by Marco Booldt,et.al., Vehicular Tech Conference 1998 VTC 98 48th IEEE vol. 3, pp. 2590-2593, vol. 3, Apr. 1998.*
Transmission of compressed voice over integrated services frame relay networks: priority service and adaptive buildout delay. by Dong, L; Kay,A.R.;Mahmoud, S.A., Apr. 1994.

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