WiMAX Network Architecture and Emergency
- Status Update –
7th Emergency Services Workshop
College Park, MD, USA - 11-13 May 2010
Contact: dirk.kroeselberg@nsn.com,
Nokia Siemens Networks
2010-05-11
Thanks to Greg Schumacher and Ming Lai
for additional input!
WiMAX Forum Standards Activities
● The WiMAX Forum (www.wimaxforum.org) develops
● Requirements in the Service Provider WG (SPWG)
● A standardized network architecture
● in the Network WG (NWG)
● where most emergency efforts take place
● Radio interface profiles
● in the Technical WG (TWG)
● based on IEEE 802.16-2009 and 802.16m
Releases of the WiMAX network standards
● Release 1.0 published in 2007
● Release 1.5 published in 2009
● many enhancements, some new features
● Emergency support: citizen-to-authority, focused on emergency
access
● IMS support: 3GPP IMS with WiMAX-specific discovery, Policy
and Charging Control (PCC) support
● Standardized Location support
● Detailed presentation from ES-Workshop05 (Vienna, 2008):
http://www.emergency-servicescoordination.info/2008Oct/slides/esw5-wimax.pdf
Releases of the WiMAX network standards
● Release 1.6 (under final review, will be published during 2010)
● introduces network-initiated priority treatment for Emergency
Telecommunications Service (ETS)
● Release 2.0 (specification development started recently)
● enhancements to emergency call support and ETS planned
● References for Release 1.5:
● Core Specification (stage-3):
http://www.wimaxforum.org/sites/wimaxforum.org/files/technical_document/2009/09
/WMF-T33-001-R015v01_Network-Stage3-Base.pdf
● Emergency Services Support:
http://www.wimaxforum.org/sites/wimaxforum.org/files/technical_document/2009/09
/WMF-T33-102-R015v02_Emergency-Services.pdf
● Location based Services (LBS):
http://www.wimaxforum.org/sites/wimaxforum.org/files/technical_document/2009/09
/WMF-T33-110-R015v01_LBS.pdf
ES Roaming Reference Architecture
Visited NSP
NAP
Home NSP
R2
R2
R3
ASN
SS/MS
VoIP
client
R1
R5
AAA
AAA
LS
LS
LC
LR
CSN
CSN
R3
R4
RV
RV
V-VSP
H-VSP
VoIP
Server
VoIP
Server
PSTN
GW
PSTN
GW
Another ASN
Legend of lines:
Bearer plane:
Control plane:
PSAP
PSAP
ES network entry overview
● The ES specification (WMF-T33-102-R015) focuses on network
access
● Placing an emergency call while already on the network is
handled by the VoIP application (separate spec like for IMS)
● WiMAX uses EAP/AAA-based network entry
● EAP = Extensible Authentication Protocol, IETF RFC 3748
● Access security and authorization via EAP methods
● Set up quality-of-service profiles with RADIUS/Diameter
● Network (visited CSN) selection supported via NAI decoration
● Emergency is indicated through NAI decoration
● NAI = network access identifier, IETF RFC 4282
● NAI carries the user identity of the subscriber within EAP/AAA
● {sm=2} <username>@<NSPRealm> indicates emergency
● No impact or dependency on 802.16e MAC layer
Unauthorized/Unauthenticated Support in
WiMAX ES
● Unauthorized = empty prepaid, barred subscription, roaming not
allowed, etc.
● mainly depending on home operator (AAA-server) policy
● possible in WiMAX to grant limited access for unauthorized cases
● emergency is recognized during network entry, further handling
depends on operator policy
● Unauthenticated = no subscription or unrecognized subscription
● All WiMAX devices are shipped with a device certificate
● Public-key infrastructure required for certificate verification hosted by
the WiMAX Forum, see http://www.wimaxforum.org/resources/pki
● If no (user) subscription is available, network entry for emergency can
be allowed with
● using EAP-TLS as authentication method
● providing the device certificate in EAP-TLS to the network
● This simply provides an appropriate building block. Operators can
enable this, if required.
ETS support in WiMAX
● ETS = Emergency Telecommunications Service (authority-to-authority)
● Release 1.6 only provides an initial specification that allows ETS priority
signaling within the WiMAX network
● No specific considerations for the 802.16 radio interface
● Specification is currently under final review.
● Will be published as part of the final Release 1.6 core specifications
later in 2010.
● Opens (planned to be addressed by Release 2.0):
● Exact method to signal ETS and priority across the 802.16 radio
interface (needs harmonization of all existing emergency fields in the
wireless MAC layer (L2 of 802.16-2009 and 802.16m)
● Detailed structure of the Priority Indication field for ETS and
other emergency services (considered out-of-scope in Release 1.6)
Emergency enhancements planned for
Release 2.0 networks
● Consider radio link emergency signaling
● Current network specification only uses EAP NAI decoration for
emergency call indication. Works fine in network entry, but
difficult when the device is already attached to the network.
● IEEE 802.16-2009 and 802.16m provide an emergency
indication as part of the initial ranging message.
● 802.16-2009 and 802.16m also define several emergency
related TLVs. Unclear how to use them in the network.
● Update specification text to better match local regulation (in
particular for the North-America region).
● Improve support for dedicated VoIP systems.
● Support for broadcast messaging and CMAS (commercial mobile
alert system) specific extensions discussed at requirements level
Comments welcome!