Hybrid Protocol Stack for LTE-5G Interworking
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Solution Overview
Problem
Current technologies face challenges in seamlessly supporting user plane dual connectivity between LTE and 5G networks, particularly in scenarios where 5G is deployed with limited nationwide coverage, leading to frequent radio access technology changes and associated mobility issues.
Innovation Solution
Implementing a hybrid protocol stack that allows 5G Non-access stratum (NAS) to run on top of LTE Radio-Resource-Control (RRC) layers, enabling service flow setup across combined LTE/5G systems, with options for interworking between legacy and new network components, including enhanced NodeBs and control gateways, to support seamless user plane connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If 5G is deployed with limited nationwide coverage, then 5G network deployment cost is reduced, but mobility robustness deteriorates due to frequent radio access technology changes
Solution Approach 1:
The patent combines LTE and 5G radio access technologies into a unified service flow framework. The network node integrates both LTE E-RAB (Evolved Radio Access Bearer) and 5G NR QoS (Quality of Service) flow handling capabilities, allowing seamless operation across both technologies without requiring separate management systems. This merging enables devices to camp on LTE networks while maintaining 5G service flows, thereby improving mobility robustness while accommodating limited 5G coverage.
Solution Approach 2:
The network node is designed with multi-functionality to handle both LTE and 5G protocols and service flows simultaneously. The system can operate in multiple modes: pure LTE mode, pure 5G mode, and hybrid dual-connectivity mode. This universal capability allows the network to adapt to varying coverage conditions and device capabilities, maintaining reliable service delivery regardless of whether the device is connected via LTE or 5G, thus resolving the mobility robustness issue caused by limited 5G coverage.
2Productivity
If hybrid protocol stack is implemented, then service flow establishment efficiency is improved, but device complexity increases
Solution Approach 1:
The patent segments the protocol stack into distinct functional layers with clear interfaces. The 5G NAS (Non-Access Stratum) protocol operates independently on top of the LTE RRC (Radio Resource Control) layer, rather than requiring a complete integration of both protocol stacks. This segmentation allows the device to maintain separate, well-defined protocol handlers for LTE and 5G, reducing the complexity of implementing hybrid functionality while enabling efficient service flow establishment through coordinated interaction between the segmented layers.
3Reliability
If dual connectivity is supported, then service quality is improved, but system complexity increases
Solution Approach 1:
The patent introduces a service flow as an intermediary construct that bridges LTE and 5G dual connectivity. Rather than managing complex direct interactions between multiple LTE bearers and 5G bearers, the service flow acts as a unified abstraction layer that coordinates resources across both radio access technologies. The network node manages the service flow end-to-end, handling QoS requirements and resource allocation, while the device benefits from simplified connectivity management. This intermediary approach maintains high service quality through dual connectivity while reducing system complexity.
Data Source
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AI summary
A method and apparatus may include providing, by a network node, an indication to a user equipment. The indication indicates that the network node supports interworking between a first radio-access technology and a second radio- access technology. The method may also include receiving a request to set up a service flow. The method may also include setting up the service flow.