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IEEE 802.21 WG Presentation Template


  • pg 1
									IEEE 802.23 Emergency Services
DCN: 23-11-0007-00-0000
Title: 802.11 call flow for Layer 2 support for unauthenticated
Date Submitted: March, 2011
Presented at IEEE 802.23 session in Singapore
Authors or Source(s): G. Scott Henderson, Research In Motion

Abstract: This contribution proposes an 802.11 call flow for Layer
 2 support for unauthenticated ES requests. It also identifies
 some changes by component required to support this call flow.

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                  ES VoIP CALL


                                                     PSTN PROXY
               802 x
      POA AP              PONA Router

                 DHCP Server                  Default SIP Server/ GW
                  Diagram Labels
A: End User Terminal (EUT)
B: Point of Attachment (POA)
   (e.g. 802.11 access point or 802.3 jack/switch port)
C: 802 infrastructure
   (intervening bridges, switches or wireless connections)
D: Point of Network Attachment (PONA) router
E: Default SIP Server / gateway
F: PSTN Proxy server
   (if the PSAP does not support IP directly)
G: PSAP Router (Direct IP support in the PSAP)
H: PSAP Station
• 802.11u and v conformance
• DHCP support
• 802.23 would define the ES VLAN and the ES call flow
  identifier (e.g. ES Ethertype, SNAP Headers or 11u UESA bit
  (clause )
• Default GW/SIP proxy address would be provided by a DHCP
  server (RFC 3361)
• Default GW/SIP proxy is similar to a P-CSCF in functionality
• Higher layer development would be similar/equivalent to 3GPP
  IMS ES support (e.g. TS 24.229, TS 23.167) and would need to
  be developed by the IETF

                     Layer 2 Call Flow (1)
• User initiates an emergency service call. EUT has no
  L2 association or authentication
• EUT scans for all SSIDs in range, for each SSID
  detected it listens to the beacon for the interworking IE
  (information element) and looks for ESR (emergency
  services reachable =1) and UESA (unauthenticated
  emergency services access = 1) bits in the
  interworking element advertising ES support (802.11u
  2011 clause X.1.5)
• EUT requests ES association (802.11u 2011 clause

                     Layer 2 Call Flow (2)
• AP bridges to an ES VLAN to the PONA router and
  maps the VLAN to only support emergency service
  traffic from the EUT from the 802.11 air interface.
• EUT records location from AP (802.11u 2011)
  (Optional for the EUT: EUT can use its own location,
  uses the AP location, or ask the AP for the EUT’s
  location.) (802.11u 2011 clause X.4.2)*
• The layer 2 session is established.

*in regulatory domains that allow/require location

                     Upper Layer Functions
• DHCP provides EUT with an IP address and the address to the
  Default GW/SIP Proxy
• The EUT signals to default SIP proxy/GW to open an
  ‘emergency context’ (comparable to an emergency bearer in
  3GPP) to/from the EUT. (3GPP 23.401)
• EUT sends an emergency SIP (unauthenticated) request (e.g.
  911 SIP invite) (using ES Ethertype) (Includes MAC id of EUT
  and AP (for callback) as well as location)
• Default SIP proxy/GW forwards call only to a PSAP/
• PSAP responds with ‘2xx ok’
• During the call and/or shortly after ending, PSAP may request
  new/updated location information
        EUT Applications Requirements
• EUT must be 802.11u and v compliant
• EUT must get location from the AP if needed
  (802.11u 2011 clause X.4.2)
• Request to AP to set up an ES call
• The call request must use an ES call flow identifier
  (ES Ethertype, SNAP Headers or 11u UESA bit)
• Upper layer requirements also need to be defined for
  the EUT

                     AP Requirements
• The access point must be compliant to 802.11u
  and v
• The AP must provide LOC info (IEEE 802.11v
• The AP must support access to the ES VLAN
  to the PONA based on incoming ES Ethertype
  (or UESA bit or SNAP Header)
• The AP must be able to bridge ES traffic to the

     PONA Router Requirements
• The router must recognize traffic arriving on
  ES VLANs as emergency requests
• The router will routes signaling and bearer
  traffic arriving over the ES VLAN to only the
  default SIP proxy/GW.
• The router will signal the default SIP
  proxy/GW to set up an ‘emergency context’.

   Default SIP Proxy/GW Requirements
• The gateway must support ‘SIP emergency
  services’ (e.g. 3GPP 24.229 clause 5.2.10)
• The SIP Proxy must forward ES call to the
  correct local PSAP
• In 3GPP terminology, this would be the P-
  CSCF (proxy call session control function)

•     IEEE 802.11v Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications
      Amendment 8: IEEE 802.11 Wireless Network Management

•     IEEE 802.11u Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications
      Amendment 9: Interworking with External Network

•     IETF RFC 3690 IP Telephony Requirements for Emergency Telecommunication Service (ETS) Feb
•     IETF RFC 3361 (DHCP-for-IPv4) Option for Session Initiation Protocol (SIP) Servers Aug 2002
•     3GPP TS 23.167 IP Multimedia Subsystem (IMS) Emergency Sessions Release 11 January2011

•     3GPP TS 24.229 10.2.0 IP multimedia call control protocol based on Session Initiation Protocol (SIP)
      and Session Description Protocol (SDP) Dec 2010

•     3GPP TS 23.401 10.0.0 General Packet Radio Service (GPRS) enhancements for Evolved Universal
      Terrestrial Radio Access Network (E-UTRAN) access June 2010

•     Draft-ietf-sipcore-location-conveyance-04, Location Conveyance for Session Initiated Protocol

•     Draft-patel-ecrit-sos-parameter-11, SOS Uniform Resource Identifier (URI) Parameter for Marking of
      Session Initiation Protocol (SIP) Requests related to Emergency Services

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