Neighbor Cell Interference Estimation in WCDMA Networks
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Solution Overview
Problem
Current wireless communication networks face challenges in accurately estimating neighbor cell interference, particularly in WCDMA networks, which affects load prediction and interference management in heterogeneous networks, leading to inefficiencies in scheduling decisions and resource utilization.
Innovation Solution
A method and system for estimating neighbor cell interference by obtaining and signaling interference-related quantities, including soft, softer, and remaining neighbor interference, based on measured load and total wideband power, allowing for improved interference management and scheduling decisions across network nodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If neighbor cell interference estimation is performed using conventional methods in WCDMA networks, then the estimation can be obtained with standard processing, but the accuracy is insufficient (inaccuracy better than 10-20% cannot be achieved) and the bandwidth is limited
Solution Approach 1:
The patent segments the neighbor cell interference estimation into multiple independent components: soft handover interference estimation, softer handover interference estimation, and remaining neighbor cell interference estimation. Each component is estimated separately using specific algorithms (Kalman filters with different parameters), allowing high-accuracy estimation of each segment while maintaining overall high bandwidth through parallel processing of these segmented components
Solution Approach 2:
The patent introduces an intermediary processing layer that separates the total received power into distinct interference components before final estimation. By using intermediate variables such as soft handover power estimates, softer handover power estimates, and remaining neighbor cell power estimates, the system achieves both high accuracy and high bandwidth in the final neighbor cell interference estimation
2Ease of operation
If the scheduler bases scheduling decisions on load prediction with inherent delays of at least 5 TTIs, then scheduling decisions can be made, but the load prediction accuracy deteriorates due to the delay between scheduling decision and interference power appearance
Solution Approach 1:
The patent performs preliminary estimation of soft handover interference, softer handover interference, and remaining neighbor cell interference before the actual scheduling decision is made. By calculating these interference components in advance using current measurements and predictive algorithms, the system compensates for the inherent 5 TTI delay, maintaining high load prediction accuracy while enabling timely scheduling decisions
Solution Approach 2:
The patent implements feedback mechanisms where the estimated interference components are continuously updated based on actual received power measurements and previous estimation errors. This feedback loop allows the system to adapt to changing network conditions and maintain accurate load predictions despite the time delay between scheduling decisions and their effects on the air interface
3Adaptability or versatility
If soft and softer handover powers are estimated separately, then the estimation process can account for different handover types, but additional inaccuracies are introduced in the load prediction and estimation steps
Solution Approach 1:
The patent segments the handover interference estimation into distinct soft handover and softer handover components, each processed through dedicated Kalman filter algorithms with handover-specific parameters. This segmentation allows the system to adapt to different handover types while maintaining accuracy by applying type-appropriate estimation methods to each segment, rather than using a single generic estimation approach that would introduce inaccuracies
4Adaptability or versatility
If more network nodes are introduced to meet heterogeneous network trends, then network coverage and capacity are improved, but operator control is reduced and interference management becomes more difficult
Solution Approach 1:
The patent enables each network node to autonomously estimate its own neighbor cell interference components (soft, softer, and remaining) using locally available measurements and standardized algorithms. This self-service capability allows nodes in heterogeneous networks to independently manage their interference without requiring complex centralized control, thereby supporting network heterogeneity while keeping interference management complexity at an acceptable level
Data Source
AI summary
Mobile broadband traffic has been exploding in wireless networks (300) resulting in an increase of interferences and reduced operator control. Networks (300) are also becoming more heterogeneous putting additional demand in interference management. There is currently no support for signalling of neighbor cell interference gleaned from soft and softer handover powers. Thus, there are no algorithms that accounts for and/or estimates interference impact factors between neighboring cells based on neighbor cell interference estimates gleaned from soft and softer handover power. To address these and other issues, techniques to accurately predict/estimate neighbor cell interferences that accurately accounts for own cell powers, soft handovers, softer handovers, neighbor cell interferences, and remaining neighbor cell interferences are presented. The described techniques estimate coupling effects of scheduling decisions in one cell to surrounding cells. In this way, interferences in the network (300) can be managed. To allow sharing of impact factors between network nodes (500), signalling techniques are also presented.