MME Handover Between CS and PS Networks
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Solution Overview
Problem
Current solutions for handover of communication services between Circuit Switched (CS) and Packet Switched (PS) networks in cellular networks require significant enhancements to the Gn/Gp Serving General Packet Radio Services Support Node (SGSN) and increased complexity in signaling, making them inefficient.
Innovation Solution
Implementing a method within the Mobile Management Entity (MME) to manage handovers by sending resource allocation requests and responses between network nodes, allowing seamless handover of communication services from CS to PS networks without the need for extensive SGSN upgrades.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If handover of communication service between CS and PS networks is implemented using traditional methods, then service continuity is maintained, but network complexity and signaling overhead increase significantly
Solution Approach 1:
The MME acts as an intermediary between the CS network (MSC server) and PS network (eNodeB, SGW), managing the handover process centrally. The MME receives handover requests from the MSC server, allocates resources in the target PS network, and coordinates the transition, thereby simplifying the overall network architecture by consolidating control functions in a single entity rather than distributing complexity across multiple network elements.
Solution Approach 2:
The handover process is segmented into distinct phases: resource allocation phase (MME requests resources from eNodeB), handover execution phase (UE switches from CS to PS network), and bearer activation phase (dedicated bearers are activated for the communication service). This segmentation allows each phase to be managed independently with specific signaling messages, reducing overall signaling complexity compared to a monolithic handover approach.
2Adaptability or versatility
If handover management is implemented with extensive SGSN enhancements, then handover capability is improved, but device complexity and upgrade requirements increase
Solution Approach 1:
The MME serves as a mediator that eliminates the need for complex SGSN enhancements. Instead of requiring the SGSN to handle inter-technology handover between CS and PS networks, the MME assumes this role, communicating with both the MSC server (CS network) and eNodeB/SGW (PS network). This intermediary approach maintains handover capability while avoiding SGSN complexity and upgrade requirements.
Solution Approach 2:
The handover management functionality is extracted from the SGSN and placed in the MME. By removing the complex handover management responsibilities from the SGSN, the patent achieves handover capability without requiring SGSN enhancements. The MME independently handles resource allocation, bearer management, and coordination between network elements.
3Reliability
If resource allocation requests are sent through multiple network nodes, then resource allocation is achieved, but signaling overhead increases
Solution Approach 1:
Multiple signaling operations are merged into single composite messages. The MME combines resource allocation requests (including bearer setup, QoS parameters, and resource requirements) into a single Handover Request message sent to the eNodeB. Similarly, resource allocation responses and bearer activation commands are consolidated, reducing the number of separate signaling exchanges compared to traditional multi-step procedures.
Solution Approach 2:
The MME performs preliminary resource allocation actions before the actual handover executes. Resources are pre-allocated in the target PS network (eNodeB and SGW) during the resource allocation phase, so that when the UE switches networks, resources are already ready. This preliminary action eliminates the need for post-handover resource setup signaling, reducing overall signaling overhead.
Data Source
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AI summary
The embodiments herein relate to method in a mobile management entity, referred to as MME (201), for enabling handover of a communication service between a circuit switched, referred to as CS, network (100a) and a packet switched, referred to as PS, network (100b). The user equipment (101) is located in the CS network (100a) and having a communications service in the CS network (100a). Handling is improved by providing communication between the MME and a mobile switching centre, MSC, server 203.