SIP Session Establishment Network Element
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Solution Overview
Problem
In 3G communication systems, there is a challenge in establishing packet switched sessions between devices connected to different types of networks, such as packet switched (PS) and circuit switched (CS) networks, as the calling party is often unaware of the called party's network connection, leading to failed session attempts and resource wastage.
Innovation Solution
A method and network element that determine whether the second communication device is connected to a network enabling the requested session, and inform the first communication device and user if it is not, using SIP messages with headers like CALL-INFO and WARNING to provide necessary information and options for the user.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a packet switched session is requested to be established with a device connected to a CS network, then the session establishment process is initiated, but the session fails and resources are wasted
Solution Approach 1:
The network performs preliminary action by checking whether the called device is connected to a PS network before attempting to establish a packet switched session. This is achieved by querying the HSS for the device's current network attachment status. By performing this check in advance, the system can prevent initiating session establishment processes that would inevitably fail, thereby avoiding waste of network resources and improving overall productivity.
2Ease of operation
If the calling party does not know the called party's network connection status, then automatic session establishment is attempted, but the user is not informed of the failure reason
Solution Approach 1:
The system implements feedback by providing the calling party with information about the called device's network connection status through SIP headers (CALL-INFO and WARNING) before the session establishment fails. This feedback mechanism allows the user to understand why the session cannot be established (i.e., the called device is attached to a CS network rather than a PS network), enabling informed decisions about whether to proceed with alternative connection types or cancel the request.
3Measurement precision
If network elements query HSS for device location, then accurate network determination is achieved, but additional signaling and processing time are required
Solution Approach 1:
The network performs the HSS query for device location information as a preliminary action during the session establishment process, specifically when receiving a SIP INVITE message. By conducting this query in advance and caching the result, the network determines the device's network attachment status before attempting session setup. This preliminary determination, while requiring some signaling time, ensures accurate network detection and prevents subsequent failures, making the time investment worthwhile for improving overall system efficiency.
Data Source
AI summary
The invention relates to a method for handling a request by a first communication device 11 connected to a network of a communication system to establish a packet switched session with a second, wireless communication device 12, which session requires the second communication device 12 to be connected to a network which enables the establishment of the session. In order to enable an enhanced handling of such a request, it is proposed that it is first determined whether the second communication device 12 is currently connected to such a network. In case it is determined that the second device 12 is not connected to such a network, a corresponding indication is transmitted to the first device 11. The user of the first device 11 is then informed via the first device 11 that the requested session cannot be established. The invention relates equally to a communication system enabling such a method and to corresponding elements 11, 13 of such a system.