Engineering Services for Protocol Implementation, Test SW Design & Test Support
in Cellular Wireless Technology

PoC - Push to talk over Cellular

Requirements Analysis & Test Demo

Issue

The PoC project illustrates adare's capabilities to help a customer in analysing market opportunities and associated test product requirements in an early stage.
The PoC project is a typical example for an agile R&D approach which immediately starts with R&D prototyping and is not limited to the usual paper work analysis. This is preferably applied in an IP-related environment, where rapid prototyping is encouraged by the availability of base tools and open standards.
PoC services have already reached significant market success mainly in North America. Today, these services represent incompatible implementations from different vendors. The Open Mobile Alliance (OMA) has recognised the need for PoC mobile  interoperability and is progressing PoC standards including corresponding test cases to prove conformance to standards.

The objectives of the PoC project were manifold and included:

  • Learn the technical characteristics of PoC
  • Learn the differences between proprietary solutions and the forthcoming OMA standards (as an indicator for standards adoption and related timeframe)
  • Provide an early test demo system

Solution

PoC proved to be a challenging mobile application which owns even four major functional aspects.

  • PoC is a service dealing with user groups,
    i.e. PoC implies group management functions
  • PoC communication requires session management
    including the agreement of media parameters, associated port numbers, possibly submission of invitations to other group members, etc.
  • Once a multi-user session is established there is a need to arbitrate access to the floor, ... and last but not least
  • Media transfer (and its replication inside the network) is to be performed

The table indicates these four functional aspects and the related technical concepts & protocols that are applied in the recently released PoC standard.

PoC

The technical concepts comprise of:

  • A group management based on the XML Document Management (XDM) which allows mobile clients to access and manage service-specific data in the network using XCAP (XML Configuration Access Control Protocol)
  • Session control based on Session Initiation Protocol (SIP) principles
  • Both SIP and XDM represent part of the network service platform concepts specfied by the 3rd generation mobile standardisation bodies 3GPP and 3GGP2. The service platforms are refered to as IP Multimedia Subsystem (IMS) in 3GPP respectively IP MultiMedia Domain (MMD) in 3GPP2.
  • The floor control is performed by using a PoC-specific Talk Burst Control Protocol (TBCP) which is embedded into RTCP messages
  • VoIP technology is applied using wireless-optimised voice AMR encoding over RTP

Pre-standard PoC implementations deviate from these technical concepts more or less depending on the actual supplier approach.
OMA compliant implementations are expected in early 2006.

The major achievement of the customer project has been the implementation of a OMA-standard compliant test demonstration which can be used in conjunction with mobile handset prototypes.

Tools & Technologies

The test demo system has been implemented in Java using Eclipse IDE and JRE. The JAIN API is applied as interface between the SIP protocol stack and actual test application. In a final step the SW and GUI of the test demo were integrated into a specific customer product environment.