Macro Cell Mobility State Control for Heterogeneous Network Handovers
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Solution Overview
Problem
In heterogeneous networks, the high density of small cells can lead to mobility issues and interference between high power and low power nodes, particularly affecting handover performance and data transfer efficiency.
Innovation Solution
Implementing separate discontinuous reception configurations for macro cells and small cells, along with the use of almost blank subframes and coordinated resource sharing, to manage user equipment associations and reduce interference, while ensuring efficient handover and data transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If small cells are introduced within macro cell to improve capacity and cell edge performance, then network capacity and coverage are improved, but mobility performance deteriorates due to frequent handovers and handover failures
Solution Approach 1:
The patent changes the parameter of cell association by introducing a mobility state parameter that dynamically determines whether a UE should associate with macro cells or small cells. Based on the estimated mobility state (low, medium, high), the system adapts the association strategy to optimize both capacity and mobility performance.
Solution Approach 2:
The patent performs preliminary estimation of the UE's mobility state before handover decisions are made. By estimating mobility state in advance based on historical handover information, the system can proactively determine the appropriate cell association strategy, preventing handover failures rather than reacting to them.
2Productivity
If high density of small cells is deployed, then network capacity is improved, but handover failure rate increases due to fast changing radio conditions at small cell edges
Solution Approach 1:
The patent introduces a mobility state parameter that changes based on UE movement characteristics. This parameter dynamically adjusts the handover strategy, allowing the system to maintain high network capacity through dense small cell deployment while reducing handover failures by identifying and managing high-mobility UEs differently from low-mobility UEs.
Solution Approach 2:
The patent implements a feedback mechanism where the system continuously monitors handover performance and uses this information to estimate and update the UE's mobility state. This feedback loop allows the system to adapt to changing radio conditions and adjust handover parameters in real-time, reducing handover failure rates in high-density small cell environments.
3Object-affected harmful factors
If separate frequency layers are used for macro cells and small cells, then interference between high power and low power nodes is reduced, but device complexity increases due to multiple frequency configurations
Solution Approach 1:
The patent makes the macro cell and small cell operate on the same frequency layer, allowing the system to serve multiple functions (coverage and capacity) on a single frequency. This universal frequency usage reduces device complexity by eliminating the need for separate frequency configurations while maintaining interference management through mobility-based cell association strategies.
4Reliability
If mobility state estimation is implemented to optimize cell association, then mobility performance is improved, but device complexity increases due to additional processing requirements
Solution Approach 1:
The patent implements a self-service mechanism where the network infrastructure (macro cell and small cells) collectively perform mobility state estimation using information already available in the system (handover messages, measurement reports). This approach improves mobility performance without significantly increasing UE processing complexity, as the estimation is distributed across network elements that already handle UE communication.
Data Source
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AI summary
A method at a UE operating in a hybrid network, the method receiving a separate discontinuous reception configuration at the UE for the macro cell than for a small cell; and configuring a receiver on the UE according to the separate discontinuous reception configurations. Further, a method at a macro cell, the method determining a mobility state of a UE; finding a service at the UE; and limiting the UE to associate only with the macro cell based on at least one of the determining and the finding. Further, a method at a UE in an environment with a macro and small cell using the same frequency, including receiving a first allocation for small cell within a common small HARQ subframe set; and receiving a second allocation for a macro cell within a common macro HARQ subframe set, wherein the sets do not overlap.