VoIP on the iPhone: Explore the Possibilities

1. VoIP on the iPhone: Imagine the Possibilities Jan Linden, VP of Engineering

2. VoIP on the iPhoneOutline • Market trends • Technology trends • Mobile VoIP challenges • Solutions and recommendations

3. Advanced Mobile and Multimedia Capabilities Evolution of IP Voice andVideo Processing Solutions Designed Specifically for VoIP PSTN Solutions Adapted for VoIP

4. Mobile Market Trends • Fixed Mobile Convergence • Mobile phone increasingly perceived as a computer • Advanced operating systems such as Apple OSX are making this a reality • Users expect to access the same applications available across multiple platforms • Increased accessibility and affordability • Network operators are introducing new pricing models to encourage uptake of data driven services and applications • IP networks enable more cost effective transport • Handset prices declining • iPhone 3G half the price of 1st Generation

5. Mobile Technology Trends • Migration from legacy cellular to next-gen networks • Allows for faster data connection • Growth of Smartphone adoption • iPhone and other dual-mode phones provide greater flexibility in connecting to available networks • All-in-one devices able to run multiple applications efficiently • Consumers can place calls and receive data simultaneously • Development of 3rd Party Applications • Operating systems, like the Apple OS X, more conducive to advanced 3rd party applications • VoIP over mobile in high demand

6. The iPhone as a VoIP Platform • iPhone most VoIP friendly phone on market… • Open APIs for easy development • Sufficient CPU resources • Support of wideband codecs • Intuitive UI makes for simple navigation between applications • Demand for 3rd party apps is higher than other phones • …but strengths present unique challenges • Running too many applications can drain resources • Usage scenarios can negatively impact voice quality • With the right voice processing software, developing VoIP applications is a cinch!

7. Technology Challenges – Network Connections • IP Networks • Latency • Jitter • Packet loss • Wireless connections • Low signal strength • Interference from users in same or neighboring frequencies • Available bandwidth varies • WiFi access point bottlenecks

8. Technology Challenges • Device Limitations • Limited processing power • Battery life • Data intensive applications can cause jitter • Mobile Environments • Tend to have excessive background noise • Hands Free operation enhances acoustic echo

9. Impact of IP Networks Delay Packet Loss Network Jitter

10. Impact of IP Networks – Latency • Major effect is “stepping on each other’s talk” • Usage scenario affects annoyance factor – higher delay can be tolerated for mobile devices • Long delays make echo more annoying 1011100 0101101 1111010 001100111

11. Sources of Latency • Codec • Capture • Playout • Network delay • Jitter buffer • OS interaction • Transcoding Speech Encoding IP Interface Pre- Processing A/D IP Network A/D Pre-processing Speech encoding IP interface Speech Decoding Jitter Butter Post- Processing D/A IP Network D/A Post-processing Speech decoding Jitter buffer

12. 4 3 Mean Opinion Score 2 1 0 250 500 750 One-way transmission time [ms] Impact of Latency on Voice Quality Data from ITU-T G.114 • ITU-T (G.114) recommends: • Less than 150 ms one-way delay for most applications (up to 400 ms acceptable in special cases) • Users have become accustomed to longer delays • Still, low delay very important for high quality

13. Impact of IP Networks – Packet Loss and Jitter • 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

14. Technology Challenges – Mobile Environments • Acoustic Echo • Speakerphone operation common for iPhones • Micropohone and speaker close • High delay in VoIP makes echo more prominent • Background Noise • Environments inherently noisy • Usage scenarios can make differentiating between speech and noise difficult

15. Technology Challenges – Devices • Limited Resources • Size limits processing power • Battery life also limited • VoIP Friendliness • Many smartphones limit access to soundcard • Device buffers add latency • Clock drift • Too much of a Good Thing • Running too many applications can drain resources • Multiple applications accessing network can result in jitter

16. VoIP Design Considerations Speech Quality Cost Quality Time to Market Cost Signaling Ease of Use Infrastructure Flexibility Network Impairments Features Device Considerations Power Consumption

17. Mobile VoIP Design Considerations Environment – Background Noise, Room Acoustics, etc. Codec Speech Codec Hardware Network Coping with Network Degredation VoIP Design Challenges Power Consumption Power Echo Cancellation Echo Hardware Issues (Processor, OS, Acoustics, etc.) Additional Voice Processing Components Voice Environment

18. Speech Codec • Many conflicting parameters affect choice of codec • Determines upper limit of quality • Support of several codecs necessary • Interoperability • Usage scenario • IPR issues a significant concern Packet-loss Robustness Complexity Complexity Memory Delay Speech Codec Input Signal Robutness Bit-rate Bit-rate Sampling Rate Quality

19. Audio Bandwidth Effect on Quality Quality • Better than PSTN quality is achievable in VoIP • Utilizing full 0 – 4 kHz band in narrowband • Wideband coding offers more natural and crispier voice CD -Audio GIPS Wideband Speech Std Wideband Speech (e.g. G.722.2) GIPS Narrowband Speech Std Narrowband Speech Implementation (PSTN) 200 - 3400 Hz 3,4 4 kHz 6.4-7.0 kHz 22.1 kHz 8 kHz Frequency

20. iPhone Specific Challenges • Applications cannot run in the background • Audio HAL APIs (regular APIs) not available on iPhone. (As on Mac.) Very iPhone specific solution had to be designed • Must consider change of audio route (e.g. headset in/out) and handle this • Wideband audio not available via built-in mic  

21. Recommendations • IP Networks • No need for dedicated bandwidth if solution includes high performance: • Bandwidth management • Robust codec framework • Low latency achieved by efficient jitter buffer • Audio • High quality audio is crucial • Users expect the same quality they experience on the PC • Optimized Solutions • Efficiency for ARM processors on iPhones • Reduce CPU constraint and increase battery life

22. Recommendations • Adaptive Jitter Buffer and PLC • Manage up to 30% packet loss • Adapt to network busts and excessive mobile jitter • Codecs Designed for IP Networks • Work in tandem with jitter buffer to overcome packet loss • Can deliver Wideband experience • Robust and bit-rate adaptive codecs necessary • Efficient use of the total available bandwidth • GIPS iLBC already in the iPhone, GIPS iSAC and other wideband codecs provide even better user experience • Aggressive Voice Quality Enhancement • Detect and cancel background noise • Suppress acoustic echo

23. Recommendations • VoiceEngine Mobile for iPhone • Comprehensive package of voice processing components • Handles delay, jitter, packet loss and mobile environments • Optimized for iPhone and Smartphones • Efficient solution reduces CPU demands • Flexible and easy to integrate