OMA PoC Overview and draft-allen-sipping-poc-p-headers

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OMA PoC Overview anddraft-allen-sipping-poc-p-hea
ders

• Andrew Allen Research In Motion
• Tom Hiller Lucent Technologies

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Latest Public OMA PoC Specs

• http//member.openmobilealliance.org/ftp/Public_do
  cuments/POC/Permanent_documents/OMA-AD-PoC-V1_0-20
  050308-D.zip
• http//member.openmobilealliance.org/ftp/Public_do
  cuments/POC/Permanent_documents/OMA-TS-PoC_Control
  Plane-V1_0-20050308-D.zip
• http//member.openmobilealliance.org/ftp/Public_do
  cuments/POC/Permanent_documents/OMA-TS-PoC_UserPla
  ne-V1_0_16-20050308-D.zip

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PoC Concepts

• PoC (Push to Talk over Cellular) Concepts
• Supports PoC Sessions featuring half duplex
  media from one participant to other participants.
  PoCv1 focuses on audio.
• Uses SIP signaling, and has numerous references
  to 3GPP/2 IMS/MMD, but in no way precludes non
  IMS/MMD based SIP networks. Also, OMA is access
  network agnostic.
• Can set up a PoC session to one user, a URI list
  of users, or a (flat) pre-arranged group of users
  
• Floor Control arbitrates one speaker with the
  right to speak an indication (e.g., audible
  tone) indicates when to speak
• Manual and Auto-Answering modes supported
• Manual Answer Override (MAO) supported, e.g., for
  emergency dispatch purposes
• Confirmed and an unconfirmed indication to speak

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OMA PoC Architecture
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PoC Server Functions

• Participating PoC Function (PF)
• SIP application residing in the home network of
  the user
• Provides policy enforcement for incoming PoC
  Session (e.g. Access Control, Incoming PoC
  Session Barring, availability status, etc)
• Stores the current Answer Mode, Incoming PoC
  Session Barring and Incoming Instant Personal
  Barring preferences of the PoC Client.
• Can arbitrate the active PoC sessions for
  simultaneous PoC sessions
• Controlling PoC Function (CF)
• A SIP application that can invite requested users
  or determine the participants of a group
• Acts as the Focus for the PoC Session
• Provides a centralized media distribution
• Provides a centralized floor control
  functionality
• May buffer some talk bursts

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On Demand Call Model

• On-Demand Session
• Conventional end-to-end INVITE initiated PoC
  session establishment time
• An INVITE is an implicit floor request at
  establishment and a 200 OK response can carry
  an SDP based floor grant indication.

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Pre-established Session

• Pre-established Session
• Uses a long held SIP session (setup with an
  INVITE) between the PoC Client and its
  Participating PoC Function prior to Push-to-Talk
  time negotiates codecs, floor control protocol,
  etc.
• Call establishment request is an in-dialog REFER
  request to add users to the pre-established
  session.
• REFER is an implicit floor request
• Makes significant use of an OMA specified floor
  control (and if desired SIP notifications) to
  convey session establishment and the PoC Session
  URI
• Fewer bytes than an INVITE and possibly no SIP at
  the mobile terminating side at PoC session setup

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Latency Challenge

• Dormant activation and limited over-the-air
  connection bandwidth offer challenges to PoC
• PoC indication to speak latency requirement is
  typically to be under two seconds for the
  unconfirmed indication in auto answer mode
• Unconfirmed floor control indication permits the
  originating user to speak before a terminating
  user responds to SIP signaling CF PoC server
  buffers

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Example Scenario
INVITE (P-Alerting-Mode MAO)
MAO Authorization
INVITE (P-Alerting-Mode MAO)
INVITE (P-Alerting-Mode MAO)
Answer mode Authorization
183 Session Progress (P-Answer-State Unconfirmed)
INVITE (P-Alerting-Mode MAO)
200 OK (P-Answer-State Unconfirmed)
200 OK (P-Answer-State Unconfirmed)
PoC Client Auto Answers
Media
Media Buffering
200 OK
200 OK (P-Answer-State Confirmed)
Media
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draft-allen-sipping-poc-p-headers

• P-Alerting-Mode
• Allows an originating PoC Client or PoC Server to
  request a particular answering mode (i.e.,
  Manual, Auto, MAO).
• P-Answer-State
• Allows a PoC Server to indicate in a response
  whether the session is established end-to-end or
  only as far as an intermediate node. In PoC this
  is the terminating PoC PF Server
• Needed to enable media buffering prior to called
  party answer (early right to speak indication)
• Needed to provide and indication to the caller
  that early right to speak buffering is taking
  place

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P-Alerting-Mode

• Values
• Manual
• Auto
• MAO
• Methods
• INVITE
• REFER
• Security Assumptions
• Authorization Mechanisms for requested mode
• Integrity Security between PoC Server and PoC
  Client if PoC Server performs the Authorization

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P-Answer-State

• Values
• Confirmed
• Unconfirmed
• May be included in Responses
• 1XX (typical 183 Session Progress)
• 200 OK
• Responses may or may not contain SDP
• May be included in a SIP Frag
• NOTIFY sent as a result of subscription
  established by REFER
• Security Assumptions
• Trusted PoC Server has knowledge of currently
  selected Answer Mode of the terminating PoC
  Client
• Originating PoC Client relies on a PoC Server to
  buffer media

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Thank you

• Questions?