Dynamic Handover Margin Forecasting for Wireless Devices
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Solution Overview
Problem
Existing handover techniques in wireless communications often result in increased handover delay, especially in non-line of sight and fast fading environments, due to the use of fixed handover margins, which can lead to suboptimal signal quality and connectivity issues.
Innovation Solution
A handover scheme that varies the handover margin based on probability forecasts of signal strength, using time-series forecasting techniques like ARIMA models to predict future signal strengths, allowing for proactive selection of the best available access point or base station, thereby reducing computational complexity and minimizing handover delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed handover margin is used to determine handover trigger conditions, then ping-pong handovers are prevented, but handover delay increases in non-line of sight and fast fading environments
Solution Approach 1:
The handover margin is transformed from a fixed value to a dynamic value that changes based on environmental conditions. The system adapts the margin magnitude according to the detected propagation environment (line-of-sight vs. non-line-of-sight) and signal fading characteristics, allowing smaller margins in fast-fading environments to reduce handover delay while maintaining stability in stable environments.
Solution Approach 2:
The handover margin parameter is modified based on environmental parameters. The system measures signal characteristics (RSSI variations, fading rate) and adjusts the margin parameter accordingly - using smaller margins when fast fading is detected and larger margins when the environment is stable, thus optimizing the trade-off between handover stability and delay.
2Reliability
If a large handover margin is used, then handover stability is improved, but handover delay increases
Solution Approach 1:
The handover margin dynamically adapts to environmental conditions rather than remaining large and fixed. In fast-fading environments, the margin is reduced to enable timely handovers, while in stable environments, the margin is increased to ensure stability, thus eliminating the need to consistently use large margins.
Solution Approach 2:
The margin parameter is adjusted based on measured signal characteristics. When rapid signal variations are detected, the system decreases the margin parameter to reduce delay; when signal stability is high, the system increases the margin parameter to maintain stability, achieving context-optimal margin values.
3Device complexity
If reactive handover decisions are made based on current signal strength, then simplicity is maintained, but handover delay increases in fast fading environments
Solution Approach 1:
The system performs preliminary measurements and environmental assessment before making handover decisions. By detecting propagation characteristics and fading rates in advance, the system can prepare appropriate margin values and trigger conditions, enabling faster reaction to signal degradation without overly complex real-time processing.
Solution Approach 2:
The system continuously monitors signal characteristics and uses this feedback to adjust handover parameters. By measuring RSSI variations and fading patterns, the system adapts the handover margin and trigger thresholds in real-time, creating a responsive system that balances simplicity with fast reaction capability.
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~4
AI summary
A method of triggering a network handover controlled by a communications device in a communications system comprising a plurality of networks with which the communications device can perform a handover operation to, the method comprising the steps of: determining a signal characteristic of each available candidate network in said communications system; forecasting a future value of said signal characteristic; determining a future handover margin for said signal characteristic of the network connection established by said communications device; determining if another available candidate network signal characteristic exceeds said handover margin at a future time, and if so, performing a handover operation to said other available candidate network, wherein said future handover margin for said signal characteristic is varied dynamically in dependence on said forecasted signal characteristic.