IMS Control Message Transmission via Control Plane
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Solution Overview
Problem
The existing mobile communication systems experience increased call setup delay due to the requirement of establishing a user plane in packet-switched call setup procedures for IMS control messages, which is not present in circuit-switched systems.
Innovation Solution
The method involves determining whether a UE is registered to the IMS service and setting up an SRB_IMS entity to transmit IMS control messages directly through the control plane, utilizing existing Iu signaling connections and SRB entities to bypass the need for user plane setup, thereby reducing delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a user plane is established for transmitting IMS control messages in packet-switched call setup procedures, then the messages can be transmitted, but call setup delay increases due to the additional setup time required
Solution Approach 1:
The patent extracts the IMS control message transmission from the user plane and relocates it to the control plane. Specifically, the SGSN identifies IMS control messages (such as SIP messages) and routes them through the control plane via the RNC, bypassing the need for user plane establishment. This separation allows IMS control messages to be transmitted independently without requiring packet data network resource allocation, thereby reducing call setup delay while maintaining reliable message delivery
Solution Approach 2:
The patent introduces the SGSN as an intermediary that mediates between the GGSN and the RNC for IMS control message transmission. The SGSN receives IMS control messages from the GGSN, identifies them as control plane traffic, and forwards them to the RNC for transmission to the UE. This intermediary function enables the control plane to handle IMS signaling without requiring user plane setup, effectively bridging the gap between packet-switched network architecture and circuit-switched-like signaling efficiency
2Loss of time
If the control plane is used for IMS control message transmission without user plane setup, then call setup delay is reduced, but the system must differentiate between control plane and user plane messages
Solution Approach 1:
The patent employs protocol discrimination mechanisms that act as 'color coding' for different message types. The SGSN uses protocol discriminators to identify IMS control messages (such as SIP INVITE, REGISTER, etc.) among other packet data traffic. This identification mechanism allows the system to differentiate control plane messages from user plane data without complex additional signaling, as the message type is inherently identifiable through protocol analysis at the SGSN
Solution Approach 2:
The patent implements preliminary configuration where the SGSN is pre-configured with information about which protocol discriminators correspond to IMS control messages. This preliminary setup allows the SGSN to quickly identify and route IMS control messages through the control plane without requiring real-time decision-making complexity. The RNC is also pre-configured to handle control plane IMS messages, enabling efficient message routing while minimizing runtime complexity
Data Source
AI summary
Apparatus and Method for transmitting control message related to a packet call service in an IP multimedia subsystem (IMS) that transmits/receives an IMS control message using a control plane to reduce a delay caused by setting of a user plane in a packet call setup process. A user equipment (UE) determines whether an IMS service is registered in response to a radio resource control (RRC) connection request. The UE sets an SRB_IMS request parameter requiring that the IMS control message be processed through a signaling radio bearer (SRB) depending on whether the IMS service is registered. The UE transmits an RRC connection request message including the SRB_IMS request parameter to a radio network controller (RNC). The UE configures an SRB_IMS entity.