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Semelhante a 8 the path to voice over lte - vo lte (20)
8 the path to voice over lte - vo lte
- 1. Greater insight. Greater confidence.
Accelerate next-generation wireless.
The Path to Voice over LTE - VoLTE
with IMS (IP Multimedia Subsystem)
presented by
Andjela Ilic-Savoia
Agilent Technologies
Wireless Communications
© 2012 Agilent Technologies
2013
1
- 2. Agenda:
Greater insight. Greater confidence.
Accelerate next-generation wireless.
• Intro: a very brief history of IMS, Legacy (CS) vs. LTE (PS) domain
considerations
• Architecture of IMS, components, SIP
• IMS call: SIP call-flow
• What happens when out-of-coverage: flavors of fallbacks
• Protocol features for successful and efficient VoLTE
• Discussion, questions, comments?
Wireless Communications
© 2012 Agilent Technologies
2013
2
- 3. Agenda:
Greater insight. Greater confidence.
Accelerate next-generation wireless.
• Intro: a very brief history of IMS, Legacy (CS) vs. LTE (PS) domain
considerations
• Architecture of IMS, components, SIP
• IMS call: SIP call-flow
• What happens when out-of-coverage: flavors of fallbacks
• Protocol features for successful and efficient VoLTE
• Discussion, questions, comments?
Wireless Communications
© 2012 Agilent Technologies
2013
3
- 4. IMS - IP Multimedia Subsystem
…how it all began…
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• 3GPP defined IMS in 1999
• IMS as the framework for delivery of multimedia services was standardized
in 3GPP rel.5 for delivery of “Internet” services on GPRS. This was updated
and extended to CDMA and WLAN.
• In 2009 a group of over 40 organisations, operators, vendors etc. came
together to form One Voice, whose aim was essentially to decide or drive
the method of voice delivery on LTE through IMS.
• GSMA finally adopted VoLTE in 2010, and so did many of the industry big
companies
• The use of IMS through the Verizon LTE network in the USA has
accelerated the use of IMS development for mobile devices.
Wireless Communications
© 2012 Agilent Technologies
2013
4
- 5. Support for Voice with LTE
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2G/3G – Circuit Switched calls have an allocated resource even
during times of inactivity - even when nothing is being said
• Inefficient use of available bandwidth
• Access times between requesting resource and being able to talk were
too slow to enable a reaction based allocation reduced flexibility for
resource allocation
LTE – UE will generally only be provided resources when it is
necessary – even for voice
• Allows efficient use of network resources. If we are saying nothing
we will require no network resources
• Places stress on the network to ensure suitable access timing and
quality of service (QoS).
LTE transportation is fully IP – no circuit switched services
Wireless Communications
© 2012 Agilent Technologies
2013
5
- 6. Voice with LTE: what is the goal and
how to get there
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To deliver same standard of voice call with VoLTE as is delivered by
2G/3G.
Most agree that the long term solution for voice is to use VoIP and an IMS
based core network - However it will take time for networks to support this.
For networks which do not support IMS several technologies are considered,
namely:
• CSFB (Circuit Switched Fall Back) - single radio approach
• SVLTE or Dual Standby approach (Simultaneous Voice and Data LTE) dual radio approach
• SRVCC (Single Radio Voice Call Continuity) – Voice on LTE with CS
backup
CSFB, SVLTE and SRVCC all involve some level of I-RAT behavior
Wireless Communications
© 2012 Agilent Technologies
2013
6
- 7. Enter IMS …
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Characteristic
CS Mobile
Telephony
Legacy IP
Standards bodies
3GPP, 3GPP2
IEEE
3GPP/3GPP2 and
IEEE
CS voice
PS data
PS data and PS voice
Phone numbers
IP addresses
IP + support for legacy
phone numbers
Access Protocol
Reservation based
Reservation less
SIP provides
reservation based
protocol for voice and
video
Connection Type
Connection orientated
Connectionless
SIP provides
connection orientated
Centralised/ hierarchical/
closed
Distributed/ flat/open
IMS “walled garden”
debate
QoS
Guaranteed bandwidth
Best Effort
GBR and BE
supported
AAA
~5 billion
>500M
Will be lots!
Primary service
Addressing
technique
Architecture
No. of devices
IMS
IP Multi-Media
Service
Wireless Communications
© 2012 Agilent Technologies
2013
7
- 8. Agenda:
Greater insight. Greater confidence.
Accelerate next-generation wireless.
• Intro: a very brief history of IMS, Legacy (CS) vs. LTE (PS) domain
considerations
• Architecture of IMS, components, SIP
• IMS call: SIP call-flow
• What happens when out-of-coverage: flavors of fallbacks
• Protocol features for successful and efficient VoLTE
• Discussion, questions, comments?
Wireless Communications
© 2012 Agilent Technologies
2013
8
- 9. IMS has quite complex architecture…
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Architecture divided into:
• Application Plane, Control Plane, User Plane
Important part of Control Plane is the 1st point of contact for the UE –
The CSCF (Call Session Control Function).
CSCF is further divided into nodes:
• Proxy CSCF (P-CSCF) (acts as the entry point in the IMS core network)
• Interrogating CSCF (I-CSCF)
• Serving CSCF (S-CSCF)
Wireless Communications
© 2012 Agilent Technologies
2013
9
- 10. P-CSCF:
Proxy-Call Session Control Function of IMS
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• It is assigned to an IMS-capable UE terminal before registration (through OTA
message), and does not change for the duration of the registration.
• It may be in the home domain or in the visited domain.
• It facilitates the routing path for mobile originated or mobile terminated session
requests.
• It is responsible for allocating resources for the media flows (bandwidth
management)
• It can also compress/decompress SIP messages using SigComp, which
reduces the RTT over slow radio links.
• It provides subscriber authentication, and is responsible for the security of the
messages between the network and the user (ex: may establish an Ipsec).
• It may include a Policy Decision Function (PDF), which authorizes media plane
resources e.g. QoS over the media plane.
Wireless Communications
© 2012 Agilent Technologies
2013
10
- 11. SIP and IMS
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SIP server
IP Network
PSTN
GSM
IP Network
3G
Telephone Network
• SIP (Session Initiation Protocol) was initially designed to work in an open
homogeneous IP network
• SIP provides the signalling required to support call set-up procedures
• SIP also provides many other services (caller id, multi-party & emergency
calls…)
Wireless Communications
© 2012 Agilent Technologies
2013
11
- 12. To test VoLTE today, you need:
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• IMS/VoLTE capable device
• IMS/VoLTE capable BSE
• IMS Server
• Somebody to talk to: Either
another UE or IMS Client
emulator
Wireless Communications
© 2012 Agilent Technologies
2013
12
- 13. Agenda:
Greater insight. Greater confidence.
Accelerate next-generation wireless.
• Presentation:
• Intro: a very brief history of IMS, Legacy (CS) vs. LTE (PS) domain
considerations
• Architecture of IMS, components, SIP
• IMS call: SIP call-flow
• What happens when out-of-coverage: flavors of fallbacks
• Protocol features for successful and efficient VoLTE
• Discussion, questions, comments?
Wireless Communications
© 2012 Agilent Technologies
2013
13
- 14. IMS uses SIP
(Session Initiation Protocol)
User A
CSCF Proxy
REGISTER
User B
REGISTER
OK
OK
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Optional AKAv2 authentication and IPsec
SIP (Session Initiation Protocol)
e.g. INVITE, TRYING, RING, OK, BYE etc.
SDP (Session Description Protocol)
INVITE
e.g. m (media), a (attribute) etc.
TRYING
INVITE
TRYING
m=audio 49120 RTP/AVP 98 97
a=rtpmap:98 AMR/8000
a=fmtp:98 mode-set=7
RING
RING
OK
OK
RTP (Real-time Transport Protocol)
e.g. AMR encoded speech
ACK
ACK
RTCP (RT Control Protocol)
e.g. Send/receive quality metrics
RTP/RTCP
BYE
ACK
BYE
ACK
CSCF = Call Session Control Function
Wireless Communications
© 2012 Agilent Technologies
2013
14
- 15. IMS uses SIP
(Session Initiation Protocol)
User A
CSCF Proxy
REGISTER
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User B
REGISTER
CSCF Proxy
OK
OK
INVITE
TRYING
INVITE
TRYING
RING
RING
OK
OK
IP
ACK
ACK
ACK
User A
User B
SIP messages go via proxy server
RTP voice traffic ~ peer to peer (or via
other network nodes)
RTP/RTCP
BYE
Router/IP
network
BYE
ACK
CSCF = Call Session Control Function
Wireless Communications
© 2012 Agilent Technologies
2013
15
- 16. RTP
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Accelerate next-generation wireless.
RTP is used for the delivery of the user data,
Wireless Communications
© 2012 Agilent Technologies
2013
16
- 17. Agenda:
Greater insight. Greater confidence.
Accelerate next-generation wireless.
• Intro: a very brief history of IMS, Legacy (CS) vs. LTE (PS) domain
considerations
• Architecture of IMS, components, SIP
• IMS call: SIP call-flow
• What happens when out-of-coverage: flavors of fallbacks
• Protocol features for successful and efficient VoLTE
• Discussion, questions, comments?
Wireless Communications
© 2012 Agilent Technologies
2013
17
- 18. What if…LTE/IMS out of coverage?
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Accelerate next-generation wireless.
Then:
the Voice call to work would require some level or I-RAT.
Let’s examine each of the voice related I-RAT behaviors separately.
Wireless Communications
© 2012 Agilent Technologies
2013
18
- 19. Phone x Network Configuration
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1xRTT/eVDO/
eHRPD
LTE
GSM/W-CDMA/
TDSCDMA
SVLTE Simultaneous Voice & LTE aka Dual Standby
•Two phones in one case
•1xRTT (or GSM/W-CDMA) chipset for all voice calls (CS only)
•LTE/eVDO/eHRPD (and/or W-CDMA) separate chipset for data
e.g.
LTE/eVDO/HRPD radio
GUI
1xRTT CS radio
CS Voice Client
Wireless Communications
© 2012 Agilent Technologies
2013
19
- 20. Phone x Network Configuration
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1xRTT/eVDO/
eHRPD
LTE
GSM/W-CDMA/
TDSCDMA
CSFB Circuit Switched Fall Back
•Handover from LTE to legacy 2G/3G for ALL voice calls
•Use Circuit switched voice (and if available parallel slower legacy data)
e.g.
LTE/W-CDMA/GSM radio
GUI
CS Voice Client
Wireless Communications
© 2012 Agilent Technologies
2013
20
- 21. Phone x Network Configuration
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1xRTT/eVDO/
eHRPD
LTE
GSM/W-CDMA/
TDSCDMA
LTE / IMS Islands
•Differentiated quality/price IMS voice in LTE coverage areas
•End call at LTE edge
•1xRTT for E911 and wide area coverage (CS only)
E.g.
LTE/W-CDMA/GSM radio
IMS Voice Client
GUI
1xRTT CS radio
CS Voice Client
Wireless Communications
© 2012 Agilent Technologies
2013
21
- 22. Phone x Network Configuration
Greater insight. Greater confidence.
Accelerate next-generation wireless.
1xRTT/eVDO/
eHRPD
LTE
GSM/W-CDMA/
TDSCDMA
SRVCC Single Radio Voice Call Continuity
•IMS voice calling in LTE coverage areas
•Quickly handover from LTE to legacy 2G/3G at LTE edge
e.g.
LTE/W-CDMA/GSM radio
IMS Voice Client
GUI
CS Voice Client
Wireless Communications
© 2012 Agilent Technologies
2013
22
- 23. Phone x Network Configuration
Greater insight. Greater confidence.
Accelerate next-generation wireless.
1xRTT/eVDO/
eHRPD
LTE
GSM/W-CDMA/
TDSCDMA
SVLTE
CSFB
Simultaneous Voice & LTE
Aka Dual Standby
Circuit Switched
Fall Back
e.g.
LTE/ IMS
islands
SRVCC
LTE / IMS only
Single Radio Voice
Call Continuity
Most Operators will skip some steps
World phones will need to roam with many network configurations
LTE/eVDO/HRPD/GSM/WCDMA/ TDSCDMA radio
1xRTT CS radio
IMS Voice
Client
GUI
CS Voice Client
Wireless Communications
© 2012 Agilent Technologies
2013
23
- 24. Agenda:
Greater insight. Greater confidence.
Accelerate next-generation wireless.
• Intro: a very brief history of IMS, Legacy (CS) vs. LTE (PS) domain
considerations
• Architecture of IMS, components, SIP
• IMS call: SIP call-flow
• What happens when out-of-coverage: flavors of fallbacks
• Protocol features for successful and efficient VoLTE
• Discussion, questions, comments?
Wireless Communications
© 2012 Agilent Technologies
2013
24
- 25. LTE Protocol features that will affect
how VoLTE performs
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• Multiple PDNs
• QoS through QCI - QoS class identifier
•
TFT – Traffic flow Template
• SPS – semi-persistent scheduling
• TTI bundling
• RoHC – Robust header compression
• SigComp –SIP Signaling compression
• Ipsec – security tunneling
• …
Wireless Communications
© 2012 Agilent Technologies
2013
25
- 26. Protocol Features:
VoIP QoS and Multiple PDN’s
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Accelerate next-generation wireless.
Strict packet delay-based QoS
QoS will vary by allocation, by
application and will be heavily
dependent on system capacity.
UE’s can have multiple data streams,
Multiple PDN’s, Addresses, Port
numbers etc. – All with different
parameters:
•Default DRB or Dedicated DRB
•Guaranteed or non Guaranteed Bit Rate
•Packet delay budget e.g. 50 to 300ms
•Packet Error rate e.g. 10-2 to 10-6
Wireless Communications
© 2012 Agilent Technologies
2013
26
- 27. continued…QoS class identifier : QCI
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Accelerate next-generation wireless.
Wireless Communications
© 2012 Agilent Technologies
2013
27
- 28. Protocol Features: Traffic Flow Template
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Accelerate next-generation wireless.
IP packets
Applications
o TFT is set of packet filters ~ EPS bearer
o TFT decides on IP traffic priority
o Sort IP packets based on:
•IP protocol; e.g. UDP, TCP
•Port number
•IP address
•Priority
Example configuration
Internet
Dedicated
IMS-SIP
RTP
Non-GBR, low error
IPv4/6
address 1
IPv6
address 2
TFT
e.g. IMS-SIP signalling
IP1
IP2
SIP
LTE Radio
GBR, high error
Default
e.g. Browser
e.g. RTP voice stream
RF UE
Wireless Communications
© 2012 Agilent Technologies
2013
28
- 29. Protocol Features:
GBR, TFT, QoS, DRB’s signalled to UE
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Dedicated bearer, linked to
default bearer
GBR
TFT
Negotiated
QoS
Wireless Communications
© 2012 Agilent Technologies
2013
29
- 30. Protocol Features:
Semi-persistent scheduling (SPS)
•
Normal LTE operation – each SF is
allocated individually.
•
For highly repeatable applications such
as voice this is un-necessary waste of the
DL signalling channel bandwidth.
•
In voice we normally only need a few
100’s of bits at regularly spaced intervals.
•
Greater insight. Greater confidence.
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SPS is used to tell the UE to use specific
resources for a fixed time period and can
reduce significantly the DL signalling
bandwidth required.
Normal allocation - Each time an allocation is made, PDCCH resources are required
DL Normal
DL after
SPS is
scheduled
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5
SPS allocation – reduced PDCCH signalling
Wireless Communications
© 2012 Agilent Technologies
2013
30
- 31. Protocol Features: TTI bundling
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Accelerate next-generation wireless.
If at the cell edge, UE can either increase power or increase coding rate to ensure
reception at eNB
If the UE cannot increase its power - eNB gets power headroom status reports from
each UE, the UE can be instructed to use TTI bundling.
TTI bundling prevents round trip ACK/NACK delays by transmitting all Redundancy
versions in successive TTI’s.
DL signalling is reduced (less ACKs/NACKs) and round trip delay is minimized.
NACK
NACK
NACK
ACK
DL: TTI
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9
UL: RV#
0
DL: TTI
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9
UL: RV#
0 1 2 3
1
2
3
0 1 2 3
ACK
0 1 2 3
Normal transmission with HARQ feedback
delay of 4ms for each 8ms HARQ cycle – up
to 28ms for final ACK.
Bundled TTI HARQ process 0 in 4
consecutive TTI’s (different RV). Total
feedback delay is only 8ms.
ACK
Wireless Communications
© 2012 Agilent Technologies
2013
31
- 32. OTA Messages example:
SPS and TTI Bundling
Greater insight. Greater confidence.
Accelerate next-generation wireless.
Wireless Communications
© 2012 Agilent Technologies
2013
32
- 33. Protocol Features:
ROHC - Robust Header Compression
Greater insight. Greater confidence.
Accelerate next-generation wireless.
Typical VoIP Header for IP v4/v6 = 40/60 Bytes
With a typical voice rate of 12kbps,
uncompressed IPv6 headers represent
approximately 60% of the data sent / received
LTE network efficiency very poor without RoHC
Robust Header Compression is therefore
required for LTE VoIP.
Compression is over the air interface only i.e.
between UE and eNB/NB/BTS
It happens in PDCP, user plane traffic only.
Wireless Communications
© 2012 Agilent Technologies
2013
33
- 34. Protocol Features: RoHC continued
Cuts IP overhead e.g. RTP streams for speech;
2:1 for IPv4, 3:1 for IPv6
•
RoHCv2 simplification robustness handling of outof-sequence packets
Greater insight. Greater confidence.
Accelerate next-generation wireless.
Applications
•
Payload
DeCompressor
RoHC
Context
Payload
Header
Payload
Compressor
RoHC
Context
LTE Radio Layers
Payload
LTE Radio Layers
LTE Radio
Header
IP packets
Network
RF UE
Wireless Communications
© 2012 Agilent Technologies
2013
34
- 35. Protocol Features:
SigComp - SIP Signalling Compression
SIP/SDP signalling
stack
State full Compressor
/De-compressor
RTP/RTCP
Media stack
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• Compresses text based SIP and SDP
messages
• Up to 3:1 compression
• Standardized by the IETF RoHC working
group
• only implemented between a UE and
P-CSCF
Wireless Communications
© 2012 Agilent Technologies
2013
35
- 36. Protocol Features: IP Sec
Greater insight. Greater confidence.
Accelerate next-generation wireless.
Tunnel Mode (VPN like)
• Entire original IP datagram encrypted
More info in
RFC4301, 4302, 4303
Transport Mode
• AH added to protect against alteration of datagrams while in transit
Normal IP traffic
IP Header
IP Header
Transport Mode
Tunnel Mode
New IP Hdr
AH
AH
Data
Data
IP Header Data
Wireless Communications
© 2012 Agilent Technologies
2013
36
- 37. Useful references
Greater insight. Greater confidence.
Accelerate next-generation wireless.
GSMA IR.92 IMS Profile for Voice and SMS
3GPP TS 34.229 IP Multimedia call control protocol based on SIP and SDP, UE conformance specification
3GPP TS 33.178 Security Aspects of early IP Multimedia Subsystems (IMS)
3GPP TS 26.114 IP Multimedia Subsystems (IMS) Multimedia telephone: Media handling and interaction
3GPP TS 26.132 Speech and video telephony terminal acoustic test specification
3GPP TS 22.173 IP Multimedia Core Network Subsystem Multimedia Telephony Service and supplementary
services
3GPP TS 23.228 IP Multimedia Subsystem (IMS) Stage 2
ITU-T P.862. Perceptual evaluation of speech quality (PESQ)
ITU-T P.863. Perceptual Objecting Listing Quality Assessment (POLQA)
PXT Website. www.agilent.com/find/PXT
Agilent IMS/SIP www.agilent.com/find/E6966A
Interactive Functional Test (IFT). www.agilent.com/find/IFT
Wireless Communications
© 2012 Agilent Technologies
2013
37
- 38. Thank you!
Greater insight. Greater confidence.
Accelerate next-generation wireless.
Questions, comments?
Thank you for attending:
The Path to Voice over LTE - VoLTE
with IMS (IP Multimedia Subsystem)
By
Andjela Ilic-Savoia
Agilent Technologies
Wireless Communications
© 2012 Agilent Technologies
2013
38
- 40. CS vs. PS
Greater insight. Greater confidence.
Accelerate next-generation wireless.
LTE PS
IMS core
emulation
RF
IP
Audio
2G/3G PS
RF
IP
RF
IMS end-point
emulation
Audio
2G/3G CS
Wireless Communications
© 2012 Agilent Technologies
2013
40
- 41. Agilent E6966A 1FP & 2FP IMS-SIP client
Greater insight. Greater confidence.
Accelerate next-generation wireless.
•
Easy to install and use Windows 7 PC-based IMS-SIP client
•
IPv4, IPv6, Voice, video, SMS, GUI
•
Audio: AMR, AMR-WB, G711 a/uLaw, G722/.1, G729, GSM, iLBC, Speex/wb voice codecs
•
AMR/AMR-WB Octet-align, bandwidth-efficient, Mode-set negotiation and fixing
•
Video: H264, H263
•
Play test files, audio loopback, auto-answer
•
Proven voice interop with VoLTE UEs
Wireless Communications
© 2012 Agilent Technologies
2013
41
- 42. Simple VoLTE Setup
Greater insight. Greater confidence.
Accelerate next-generation wireless.
Wireless Communications
© 2012 Agilent Technologies
2013
42
- 43. Audio test scenario
Human jury testing and/or PESQ with IP impairments
Greater insight. Greater confidence.
Accelerate next-generation wireless.
Delay/Jitter/Loss insertion
Agilent IMS-SIP server
Ethernet
Agilent PXT
Agilent PXT
VoLTE UE
VoLTE UE
RF
RF
Audio Analyzer
Audio in/out headphone jack
Audio in/out headphone jack
Wireless Communications
© 2012 Agilent Technologies
2013
43
- 44. Functional test scenario
IMS/CS voice calling & Inter-RAT scenarios
Greater insight. Greater confidence.
Accelerate next-generation wireless.
Agilent IMS server and
several remote clients
Agilent 8960
1xRTT cell
Ethernet
Agilent 8960
eHRPD cell
Test
automation
Agilent PXT
LTE cell
RF
Wireless Communications
© 2012 Agilent Technologies
2013
44
- 45. Delay and Jitter insertion with ZTI NetDisturb
Greater insight. Greater confidence.
Accelerate next-generation wireless.
ZTI NetDisturb
Agilent IMS-SIP server & client(s)
USB
USB-Ethernet adaptors can be used with ZTI
NetDisturb to add delay/Jitter to any Ethernet link in
the system. NetDisturb can run on a separate PC or
share a PC with Agilent IMS-SIP client and/or server
Windows XP or 7 PC
Ethernet
VoLTE UE
Delay/Jitter
insertion
http://www.zti-telecom.com/EN/NetDisturb.html
Agilent PXT
RF
Wireless Communications
© 2012 Agilent Technologies
2013
45
- 46. Agilent-B&K VoLTE Audio Test System
Greater insight. Greater confidence.
Accelerate next-generation wireless.
Agilent IMS-SIP server & client
.bat file, IPv6
router adv*
* Batch file can be used to configure Windows 7 PC
to transmit IPv6 Router Advertisements. Alternatively
an IPv6 router can be added to the connection
between a Windows 7 or XP PC and the PXT.
B&K Audio Test Software
B&K ZE 0948
Windows 7 PC
USB
VoLTE UE
Ethernet
Audio Line
in/out
Agilent PXT
RF
HATS
B&K PESQ Audio Analyzer
Wireless Communications
© 2012 Agilent Technologies
2013
46
- 47. Adding Jitter to audio quality systems
Agilent IMS-SIP server & client
Greater insight. Greater confidence.
Accelerate next-generation wireless.
.bat file, IPv6
router adv*
Delay/Jitter tool,
e.g. ZTI NetDisturb
USB
B&K Audio Test Software
Optional
Delay/Jitter added
to any link
B&K ZE 0948
Windows 7 PC
USB
VoLTE UE
Ethernet
Audio Line
in/out
Agilent PXT
RF
HATS
B&K PESQ Audio Analyzer
Wireless Communications
© 2012 Agilent Technologies
2013
47
- 48. Vzw VoLTE test plans
Greater insight. Greater confidence.
Accelerate next-generation wireless.
Device Test Plan VoIP quality
1
•PESQ testing with VoLTE link
Compliance Test Plan IMS VoIP
2
•VoLTE call processing, voice function, timers,
InterRAT
Compliance Test Plan LTE RCS
3
•Video functional, EAB
Wireless Communications
© 2012 Agilent Technologies
2013
48
- 49. Mode-sets explained
Greater insight. Greater confidence.
Accelerate next-generation wireless.
SDP examples
AMR
AMR
RTP/UDP/IP
Example 1; use AMR and only allow 12.2kbps
a=rtpmap:97 AMR/8000
a=fmtp:97 octet-align=1; mode-set=7
AMR: 8kHz sampling, 13 bit per sample,
typically 20ms frames
Mode
0
1
2
3
4
5
6
7
Bit rate kbps
4.75
5.15
5.9
6.7
7.4
7.95
10.2
12.2
Example 2; use AMR and allow several rates
a=rtpmap:97 AMR/8000
a=fmtp:97 octet-align=1; mode-set=2,3,5,5,6,7
Quality
OK
AMR-WB: 16kHz sampling, 14 bit per
sample, typically 20ms frames
Good
Mode
0
1
2
3
4
5
6
7
8
Bit rate kbps Quality
6.6
Good
8.85
12.65
V. Good
14.25
15.85
18.25
19.85
23.05
23.85
Excellent
AMR-WB gives better speech quality than
AMR at a given bit rate.
Notes:
•If client A suggests mode-set=7 and client B suggests modeset=2,3,5,5,6,7 then both will use only 7.
•If more than one mode is agreed then mode is set on an RTP
frame by RTP frame basis
•Octet-align=1 means octet align
•Octet-align=0 (or not present) means bandwidth efficient RTP
encoding
•Vzw recommends Octet align=0 and only AMR mode 7 or
AMR-WB mode 2
Wireless Communications
© 2012 Agilent Technologies
2013
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