3. Mobile Market Trends
• Fixed Mobile Convergence
– Mobile phone increasingly perceived as a computer
d d i h l ki hi
• 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
k d d l
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
4. 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
l bl k
– 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
5. 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
p g pp
– 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!
6. Technology Challenges – Network Connections
• IP Networks
– L t
Latency
– Jitter
– Packet loss
• Wireless connections
– Low signal strength
– Interference from users in
same or neighboring
hb
frequencies
– Available bandwidth varies
– Wi‐Fi access point
Wi Fi access point
bottlenecks
7. Technology Challenges
• Device Limitations
– Limited processing power
p gp
– Battery life
– Data intensive applications can
cause jitter
• Mobile Environments
– Tend to have excessive
background noise
background noise
– Hands Free operation enhances
acoustic echo
9. 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
10. Sources of Latency
• Codec
• Capture Pre‐
Pre‐ Speech
Speech IP
IP
A/D
A/D processin
Processing encoding
Encoding interface
Interface
• Playout g
• Network delay IP Network
IP Network
• Jitter buffer
Post‐
Post‐
Post Speech
Speech
Speech
Speech Jitter
Jitter
Jitter
• OS interaction
i i D/A
D/A processin
Processing
g
decoding
Decoding buffer
Butter
• Transcoding
11. Impact of Latency on Voice Quality
4
ore
Mean Opinion Sco
3
2
1
0 250 500 750
One-w ay transmission time [ms]
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)
t bl i i l )
• Users have got used to longer delays
– Still, low delay very important for high quality
12. 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
Transmission time differs for each packet
– Jitter buffer necessary to ensure continuous playout
– Trade‐off between delay and quality
13. Technology Challenges – Mobile Environments
• Acoustic Echo
– Speakerphone operation common for iPhones
– Microphone 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
noise difficult
14. 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
y
– Clock drift
• Too much of a Good Thing
– Running too many applications can drain
Running too many applications can drain
resources
– Multiple applications accessing network
j
can result in jitter
15. VoIP Design Considerations
Speech Quality
Quality Cost
Time to Market
Cost Signaling
Ease of Use
Flexibility
y Infrastructure
Network Features
Impairments Device
Power Considerations
C
Consumptionti
16. Mobile VoIP Design Considerations
Hardware Issues
Hardware Issues
Codec
Speech Codec (Processor, OS,
Acoustics, etc.)
Network Hardware
Coping with Network
Coping with Network
Degredation Power Consumption
VoIP Design
Challenges Power
Echo Cancellation
Echo Cancellation Echo
Environment – Background
Noise, Room Acoustics,
Additional Voice etc.
Processing Components
g p Voice Environment
17. Speech Codec
• Many conflicting parameters Packet‐loss
Complexity
affect choice of codec
affect choice of codec Robustness
• Determines upper limit of
Delay Memory
q
quality
y
• Support of several codecs Speech Codec
necessary Input Signal
Input Signal
Bit‐rate
Robutness
– Interoperability
– Usage scenario Sampling
Quality Rate
R
• IPR issues a significant
concern
18. Audio Bandwidth Effect on Quality
Quality
CD ‐Audio
GIPS Wideband Speech
Std Wideband Speech
p
(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 8 kHz 22.1 kHz
Frequency
• Better than PSTN quality is achievable in VoIP
– Utilizing full 0 – 4 kHz band in narrowband
– Wideband coding offers more natural and crispier voice
19. Recommendations
• IP Networks
– N
No need for dedicated bandwidth if solution includes high
d f d di t d b d idth if l ti i l d hi h
performance:
• Bandwidth management
• Robust codec framework
– Low latency achieved by efficient jitter buffer
• Audio
– Hi h
High quality audio is crucial
lit di i i l
• Users expect the same quality they experience on the PC
• Optimized Solutions
p
– Efficiency for ARM processors on iPhones
– Reduce CPU constraint and increase battery life
20. Recommendations
• Adaptive Jitter Buffer and PLC
– Manage up to 30% packet loss
Manage up to 30% packet loss
– Adapt to network busts and excessive mobile jitter
• Codecs Designed for IP Networks
g
– 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
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
21. 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
Efficient solution reduces CPU demands
– Flexible and easy to integrate
