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Priority, Pre-Emption, and Quality of Service
http://www.pscr.gov
Public Safety Communications Research ProgramDepartment of Commerce – Boulder Labs
Presentation by:
Tracy McElvaneyElectronics Engineer – NIST
http://www.pscr.gov/http://www.pscr.gov/
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Acknowledgement
Funding for the work presented was provided
By
FirstNet
DHS Office of Interoperability and CompatibilityDHS Office of Emergency Communications
NIST
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Overview of Priority, Pre-Emption, QoS
• Priority, Pre-emption, and QoS showed up in 3GPPstandards in the Release 8 timeframe
– Just because it’s in the standards, doesn’t mean it’s inthe product
– Just because it’s in the product, doesn’t mean it meetspublic safety’s needs
Let’s take a look at the fundamental
priority, pre-emption and QoS mechanisms.
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The “Network”
E-CSCF
P-CSCF
S-CSCF MGCF
HSS
Cx
IP Multimedia Networks
IMS-MGW
CS Network
Mn
Mb
Mg
Mm
MRFP
Mb
Mr
Mb
Legacy mobile
signalling Networks
I-CSCF
Mw
Mw
Gm
BGCF Mj Mi
BGCF
Mk Mk C, D,
Gc, Gr
UE
Mb
Mb
Mb
MRFC
SLF
Dx
Mp
CS
CS
Rx
Mm
LRF
Ml
Le
BGCF
Mi
LCSClient
Cx
Dx
AS
Sh
Ut
Mw
ISC
IBCFMx
Mx
Mx
Ma
Dh
TrGWIzi
Ici Ix
Mg
eNB
MME / S-GW MME / S-GW
eNB
eNB
S 1 S 1
S 1
S 1
X2
X 2X 2
E-UTRAN
SGi
S12
S3
S1-MME
PCRF
Gx
S6a
HSS
Operator's IPServices
(e.g. IMS, PSS etc.)
Rx
S10
UE
SGSN
LTE-Uu
E-UTRAN
MME
S11
S5 Serving Gateway
PDN Gateway
S1-U
S4
UTRAN
GERAN
Evolved UMTS Terrestrial
Radio Access Network
Evolved Packet Core
IP Multimedia System
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The Simple Network
AirInterface
Network
Backhaul
IMS
EPC
CELL
YOU
Your network will become congested.
Quality of Service allows public safety to confidently use
LTE when the network becomes congested.
Why is QoS such a big deal?
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Today’s Discussion
AirInterface
Network
Backhaul
IMS
EPC
CELL
YOU
Provide an End User perspective on QoS functionality
1. QoS can improve access to the network (or cell)
2. QoS can improve allocation of network resources3. QoS can improve end user experience
4. Give a brief update on the FirstNet QoS evaluation
Why does QoS seem so complicated?
• It is End to End
• It is highly customizable
• It is a collection of “mechanisms”
• It can be applied to many areas
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Improving Access
AirInterface
Network
Backhaul
IMS
EPC
CELL
YOU
We’ll discuss three ways to improve access to a cell:
1. Priority Access/Handover
2. Reserve a cell (for Operator use)3. Restrict Access to a Cell (Access Class Barring)
You have Class! (Access Class that is)
• 0-9 Normal Use
• 10 Emergency Use• 11 PLMN Use
• 12 Security Services
• 13 Public Utilities
• 14 Emergency Services
• 15 PLMN Use
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Priority Access/Handover
AirInterface
Network
Backhaul
IMS
EPC
CELL
YOU
Bang!
Yikes!
1. Priority access means you can access
the cell during times of congestion.
When requesting a
connection, you can
send a High Priority
Establishment CauseAir
Interface
You can also get
priority on handover
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Configured at Cell
Reserve a Cell
Network
Backhaul
IMS
EPC
CELL
YOU
2. A cell can be reserved for use “by operator”
Broadcast
to all UEs
Access Class List
• 0-9 Normal Use
• 10 Emergency
• 11 PLMN Use
• 12 Security Services
• 13 Public Utilities
• 14 Emergency Services• 15 PLMN Use
12 13 14
Air
Interface
11
AirInterface
Backhaul
Network
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Configured at Cell
Restrict Access to a Cell
Network
Backhaul
IMS
EPC
CELL
YOU
3. Restrict Access to a Cell (Access Class Barring)
Broadcast
to all UEs
Access Class List• 0-9 Normal Use
• 10 Emergency Use
• 11 PLMN Use
• 12 Security Services
• 13 Public Utilities
• 14 Emergency Services• 15 PLMN Use
0-9 0-9 0-9
11
AirInterface
Network
Backhaul
Air
Interface
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Improving Allocation of Resources
AirInterface
Network
Backhaul
IMS
EPC
CELL
YOU
First, let’s look at the device and how it sends/receives data.
Your Device can do lots of stuff
• Voice
•Video
• Data
It can even do multiple things at once!
To do this your device
creates EPS bearers
“Call or Session”
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Improving Allocation of Resources
AirInterface
Network
Backhaul
IMS
EPC
CELL
YOU
Before we talk Pre-emption, lets talk about your device.
An EPS bearer can be…
“Call or Session”
Default: Used for handling the call and
basic data needs
Dedicated: Used for specific applications
like voice, video or data
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Improving Allocation of Resources
AirInterface
Network
Backhaul
IMS
EPC
CELL
YOU
Before we talk Pre-emption, lets talk about your device.
An EPS bearer is also…
“Call or Session” GBR: Guaranteed Bit-Rate
Non-GBR: Non-Guaranteed Bit-Rate
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Improving Allocation of Resources
AirInterface
Network
Backhaul
IMS
EPC
CELL
YOU
Now…. Imagine every one doing that at the same time!
Allocation and Retention Priority (ARP) gives priority access to
bearer resources when the network is congested.
(Get, Change or Take)
Yikes!
?
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Finally… Pre-emption
AirInterface
Network
Backhaul
IMS
EPC
CELL
Me
Let’s look at a simple example.
You
I have a new app called “BWKiller”
- Low Priority, Preempt vulnerable
Bang!
You request priority resources to handle
something like Incident Command.
Your Configuration:ARP=1
Pre-empt Capable: TRUE
Pre-empt Vulnerable: FALSE
Your request is accepted, and because you
have a higher priority you can pre-empt
my bearer.
My Configuration:ARP=15
Pre-empt Capable: FALSE
Pre-empt Vulnerable: TRUE
Yikes!
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Improving End User Experience
AirInterface
Network
Backhaul
IMS
EPC
CELL
YOU
Let’s take another look at your device
Default Bearer (Non-GBR)
Dedicated Bearer (GBR)
Web Traffic
Email
VoIP
QoS configuration establishes the priority and
maximum bit rate parameters for the pipe.
QoS configuration also establishes the
priority, maximum bit rate and traffic flow
parameters for the flows.
QoS maps LTE priority to packet priority
markings that routers can treat the
packets with priority as well (DSCP)
Local
Database
or Service
QoS configuration establishes
the priority and maximum bit
rate parameters for you and
your device.
QoS configuration
establishes the priorityand maximum bit rate for
your network.
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Improving End User Experience
AirInterface
Network
Backhaul
IMS
EPC
CELL
YOU
QoS Parameters – Because every presentation needs an eye chart
Bit Rates
- Bearer and Flow
- Aggregate Max Rate
- Max Rate
- Guaranteed Rate
Packet Transport Priority
Traffic Flow Templates
- Map Data to Flows
- Map Flows to Pipes
- Customizable
QCI Resource Type Priority Packet
Delay Budget
Packet
Error Loss Rate Example Services
1
GBR
2 100 ms 10E-02 Conversational Voice
2 4 150 ms 01E-02 Conversational Video (Live
Streaming)
3 3 50 ms 01E-02 Real Time Gaming
4 5 300 ms 10E-06 Non-Conversational Video (Buffered
Streaming)
5
Non-GBR
1 100 ms 10E-06 IMS Signalling
6 6 300 ms 10E-06
Video (Buffered Streaming)
TCP-based (e.g., www, e-mail, chat,
ftp, p2p file sharing, progressive
video, etc.)
7 7 100 ms 10E-06 Voice, Video (Live Streaming),
Interactive Gaming
8 8
300 ms 10E-06
Video (Buffered Streaming)
TCP-based (e.g., www, e-mail, chat,
ftp, p2p file sharing, progressive
video, etc.)
*Also used for Default bearer for
non-priority subscribers.
9 9
Network Transport Priority
- 7 Classes of Service
- Differentiates between services in a class (DSCP)
- Addresses things like assured forwarding, drop
probability when traversing the network routers.
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QoS – What do we expect?
AirInterface
Network
Backhaul
IMS
EPC
CELL
YOU
ARP
Establishment Cause
MPS Priority
Paging Priority
Reservation Priority
Access Class
MPS Identifier
QoS Mechanisms QoS Capabilities
QCI, MBR, GBR, AMBR
DSCP Mapping
Overload Exemption
Advanced Priority
Multi-APN Support
Priority Signaling and Processing
Priority Bearer Establishment
Priority Bearer Modification
Rebalancing Exemption
Priority Queuing
Over Allocation
Priority CSFB
Enhanced Access
Class Barring
Priority Bearer Pre-emption
Traffic Flow
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QoS Testing Strategy
AirInterface
Network
Backhaul
IMS
EPC
CELL
UE
Bang!
1. Single Cell
Functional Testing
2. Single CellNetwork Testing
3. Handover
4. Roaming
5. Network Sharing
Load Test
(UE Sim)
Network
Analyzer
AirInterface
Internet
Backhaul
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FirstNet Update
• What’s happened in the last 3 months?
– CRADA Partners have been working hard
– RAN Load Test Research
– FirstNet Preliminary Deliverables• Lab Capability, 3GPP QoS, Future Plans
• Initial Use Case, more to come
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FirstNet Update
• What’s next?
– Test Case Creation
– Functional Testing, Initial results by July
– Lab Evolution
• Key Challenges
– Need to shore up BC14 UE area – Upstream (above RAN) loading
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Acronym Soup
General Acronyms
- 3GPP: Third Generation Partnership Project
- Bearer: An information transmission path- CSFB: Circuit Switched Fall Back
- EPC: Evolved Packet Core
- EPS: Evolved Packet System
- E-UMTS: Evolved Universal Mobile Telephone Service
- E-NodeB: Evolved Node B
- IMS: Internet Protocol Multi-Media Service
- LTE: Long Term Evolution- PLMN: Public Land Mobile Network
- RAN: Radio Access Network
- UE: User Equipment
Quality of Service Related Acronyms
- AMBR: Aggregate Maximum Bit Rate- APN: Access Point Name
- ARP: Allocation and Retention Priority
- DSCP: Differentiated Services Code Point
- GBR: Guaranteed Bit Rate
- MBR: Maximum Bit Rate
- MPS: Multi-media Priority services
- PCI: Pre-emption Capability Indicator- PVI: Pre-emption Vulnerability Indicator
- TFT: Traffic Flow Template
- QCI: Quality Class Indicator
- QoS: Quality of Service
Interactive Terms and Definitions Database (Very Useful!)
http://webapp.etsi.org/Teddi/
http://webapp.etsi.org/Teddi/http://webapp.etsi.org/Teddi/
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LTE RAN Load Testing
http://www.pscr.gov
Public Safety Communications Research ProgramDepartment of Commerce – Boulder Labs
Presentation by:
Jon CookElectronics Engineer – NIST
http://www.pscr.gov/http://www.pscr.gov/
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Reasons for Testing QoS, Priority, Preemption
• Verify QoS, Priority and Preemption features
function correctly before first responders use them – Features need to be verified before lives and property
are in peril
• Provide an opportunity for network equipmentvendors and UE vendors to debug unprovenfeatures
• Verify that pieces of equipment from various
vendors interoperate properly• RAN testing is the first portion of load testing that
PSCR will look at
d h
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RAN Load Tester Research
• How can we generate radio access network
congestion? – Hundreds of users needed
• We could hire 800 people to drive around Boulderwith band 14 UEs
• Fortunately, there are devices that simulate
hundreds of users – Movement through the coverage area can also be
simulated
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RAN Load Tester Research
• RAN load tester vendors were invited to
demonstrate their capabilities• They were given a list of 18 features desired for
testing LTE band 14 QoS, priority, and preemption
• Four vendors brought their equipment to PSCRlabs between December, 2013 and April, 2014
• PSCR staff gained knowledge on currentcapabilities of RAN load testing
• RAN load test vendors gained knowledge of publicsafety needs
RAN L d T R h
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RAN Load Tester Research
• PSCR staff had several discussions to decide
which RAN load test features are necessarybased on FirstNet needs and currentcapabilities
• Multiple vendors can provide the neededcapabilities
• Key features for a RAN load tester focused
on public safety needs were identified
RAN L d T R h
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RAN Load Tester Research
• Some key features for current needs
– 2 simultaneous cells – 400 simulated UEs per cell
– Traffic generation capabilities
– QoS, ARP test capabilities
– RAN sharing test capabilities
– Detailed statistics reporting
– RF fading within and between cells
• Expandability of RAN load tester for future needs isa key requirement
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Lab Operations and Engineering
http://www.pscr.gov
Public Safety Communications Research ProgramDepartment of Commerce – Boulder Labs
Presentation by:
Todd Bohling
Electronics Engineer – NIST
PSCR L b O ti d E i i
http://www.pscr.gov/http://www.pscr.gov/
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PSCR Lab Operations and Engineering
Sponsor
Projects
CRADA
Partners
NISTPSCR
Engineering
QoS
Small Cell
Extended Cell
LMR Integration
RAN Load Test
Upgrades
Project
Coordination
Support
Engagement
CTL Project Planning
Network Security
Facilities
Test Environment
Troubleshooting
Demo Support
Over-The-Air Sites
PSCR L b O ti
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PSCR Lab Operations
• Develop best practices in multi-vendor LTE
lab environment that is Focused on PublicSafety
• Future proofing the Lab will retain the labs
value in to the distant future• Research and Implement Operational
Support Systems (OSS)
• The future is so bright we gotta wearshades!!!
Th k Y !
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Thank You!
Public Sensitive
Questions?