Implementing HD Voice on Mobile Devices

• Global IP Solutions (GIPS)– Recognized leader in world class voice and video

processing technology for IP networks– GIPS software is deployed in over a billion end-points – Enables developers, operators and mobile

manufacturers to offer the highest quality regardless of network conditions

• Roar Hagen– Chief Technical Officer– GIPS– R&D in speech and video processing for more than 20

years– Ph.D. in Information Theory (source coding)

Where is HD Voice Most Needed?

CONFIDENTIAL

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*Best quality means clean, or perfect conditions

Best possible PSTN Quality*

Best possible Cell Phone Quality*

Hang-up, intolerable speech degradation

• Where audio bandwidth is currently most constrained

• Where intelligibility is most difficult

• Where environmental factors (background noise, echo) further impair quality

• Conferencing/Collaboration

Mobile telephony is the most in need of a quality upgrade

Mobile Quality Issues• Network Deficiencies

– Low signal strength– Wi-Fi bottlenecks– Additional delay, jitter and packet loss in IP network

• Device Limitations– Limited processing power and battery life– OS limiting access to real-time VoIP– Recording and playout

• Environmental disturbances– Acoustic Echo– Background noise

DesignChallenges

Coping with Network Degradation Power Consumption

Hardware Issues (Processor, OS, Acoustics, etc.)

Echo Cancellation

Additional Voice Processing Components

Environment – Background Noise, Room Acoustics,

etc.

Speech Codec

Network

Codec

Hardware

Echo Power

Voice Environment

Design Considerations

Impact of Poor Networks

• Packet Loss– Occurs due to flushed buffers in network nodes– Same effect if packets are too late to be used– Smooth concealment necessary

• Network Jitter– Transmission time differs for each packet– Jitter buffer necessary to ensure continuous playout– Trade-off between delay and quality

• Latency– Major effect is “stepping on each other’s talk”– Long delays make echo more annoying

Enhancing the HD Voice Experience

• Echo cancellation– Speaker and microphone placement can create echo– Hands free even more difficult– Higher audio bandwidth allows more echo– CPU limitations make full duplex difficult

• Noise suppression– Mobile environments inherently noisy– Higher audio bandwidth allows more noise

Sound and Noise

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CONFIDENTIAL

So Many Codec Options

G.729.1

G.719

G.718

RTAudio

SILK

iPCM-WB

Speex

iSAC

AAC-LDG.722.2 (AMR-WB)

G.722.1 (Siren)

G.722

BV 32

SVOPC G.711.1EVRC-WB

iSAC

G.722

G.711.1

MUSHRA Test Results For Different Codecs

Summary

• Mobile (and conferencing) in most need of HD– But also have the most challenges

• Need overall high quality HD design– Delay, Packet Loss, Jitter handling– Suitable codec designed for IP networks– Echo Cancellation, Noise Suppression, Gain Control– Conference Mixing

• New devices more powerful and open (Android)– Easier to provide high quality– Less need for heavy optimization of complexity