Analysis of on-off patterns in VoIP and their effect on voice traffic aggregation

Wenyu Jiang, Henning SchulzrinneDepartment of Computer Science Columbia University

Computer Communications and Networks, 2000. Proceedings. Ninth International Conference on

Estimation of Token Bucket Parameters of VoIP Traffic

R. Bruno, R.G.Garroppo and S.GiordanoDepartment of Information Engineering University of Pisa

High Performance Switching and routing, 2000. ATM 2000 Proceedings of the IEEE Conference on , 2000

Outline

• Introduction

• Experiment Setup

• Comparisons with Traditional Silence Detectors

• Token bucket simulations and results

• Conclusions

Introduction

• Human speech consists of talk-spurts and silence gaps, also known as on-off patterns.

• Allows higher bandwidth utilization through multiplexing.

• Allows per-spurt play out delay adjustment.

• Enable echo suppression based on silence detector output.

Introduction (cont’d)

energy

Pre-spurt hangover time

Post-spurt hangover time

time

Max (-20db)

Min (-45db)

Experiment Setup

3COM Ethernet Phone

3COM Ethernet Phone

Mediatrix gateway

Comparisons with Traditional Silence Detectors

• Example spurt/gap distributions

• NeVoT SD spurt and gap CDF using different parameters

• Spurt/gap distribution after averaging over many conversations

Example spurt/gap distributions

Example spurt/gap distributions

Example spurt/gap distributions

NeVot SD spurt and gap CDF using different thresholds

NeVot SD spurt and gap CDF using different thresholds

NeVot SD spurt and gap CDF using different thresholds

Spurt/gap distribution after averaging over many conversations

Spurt/gap distribution after averaging over many conversations

Spurt/gap distribution after averaging over many conversations

Token bucket simulations and results

Effect of spurt/gap distribution on multiplexing performance, G.729B

Effect of spurt/gap distribution on multiplexing performance, G.729B

Effect of spurt/gap distribution on multiplexing performance, G.729B

Multiplexing performance for NeVoT SD with default parameters

Multiplexing performance for NeVoT SD with default parameters

Multiplexing performance for NeVoT SD with default parameters

Equivalent Queuing Model

Birth-and-death Markov Chain

Simulation analysis

classifier token-bucket conditioner

Multiplexer

Conclusions

• Spurt/gap distributions are not exactly exponential, particularly for gaps.

• The token bucket simulations result indicate that the exponential model generally gives a close estimate of the out-of-profile probability.