Handover Control in Heterogeneous Networks
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Solution Overview
Problem
In heterogeneous wireless networks, the handover parameters and procedures for small cells overlaid on macro cells require adjustment to account for radio-frequency characteristics, as conventional methods fail to optimize mobility performance due to co-channel interference and differing coverage areas, leading to potential radio link failures.
Innovation Solution
The method involves determining the speed and type of handover for user equipment (UE) and adjusting parameters such as handover threshold, time-to-trigger, and layer 3 filter values based on UE speed and velocity to control handovers effectively between macro and small cells, preventing unnecessary handovers and radio link failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional handover parameters are used in heterogeneous networks with small cells, then macro cell handover performance is maintained, but handover performance deteriorates due to co-channel interference and different coverage areas
Solution Approach 1:
The patent applies local quality by configuring different handover parameters specifically for small cells versus macro cells. Handover parameters such as time-to-trigger, handover threshold, and layer 3 filter values are adjusted based on the cell type (small cell or macro cell) and UE speed, allowing each cell type to have optimized parameters suited to its coverage area and interference characteristics rather than using uniform conventional parameters
Solution Approach 2:
The patent implements dynamics by making handover parameters adaptive to UE speed conditions. The system dynamically selects different handover parameter sets based on whether the UE is moving at high speed, medium speed, or low speed, allowing the handover behavior to change in real-time according to mobility conditions while accounting for small cell characteristics
2Speed
If handover is allowed in high speed conditions, then mobility is maintained, but radio link failures increase due to co-channel interference in small cells
Solution Approach 1:
The patent applies parameter changes by modifying handover parameters based on UE speed classification. For high-speed UEs, the system adjusts parameters such as increasing time-to-trigger or modifying handover thresholds to prevent premature handovers that could lead to radio link failures, while still maintaining mobility by allowing handovers when conditions are appropriate
3Ease of operation
If handover threshold is lowered to enable more handovers, then mobility performance improves, but unnecessary handovers increase due to co-channel interference
Solution Approach 1:
The patent applies local quality by setting different handover thresholds for small cell scenarios versus macro cell scenarios. For small cells, the handover threshold is adjusted to account for co-channel interference and smaller coverage areas, preventing unnecessary handovers while still enabling mobility when appropriate, rather than using a single threshold for all cell types
Data Source
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AI summary
At least one example embodiment discloses a method of controlling a handover of a user equipment (UE) from a serving base station to a target, base station in a heterogeneous network. The method includes determining, by a serving base station, a speed of the UE and a type of the handover, the type of the handover being one of macro cell to macro cell, macro cell to small cell, small cell to macro cell and small cell to small cell, and controlling, by the serving base station, the handover from the serving base station to the target base station based on the speed of the UE and the type of handover.