Inter-Cell Interference Coordination via Selective Power Reduction
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Solution Overview
Problem
Long Term Evolution (LTE) networks face challenges in effectively managing downlink inter-cell interference in fractional frequency reuse (FFR) schemes, which affect the balance between improving rate and coverage for cell edge users and overall network throughput and spectral efficiency.
Innovation Solution
A method is introduced where cells determine whether they are non-interfering or non-interfered by neighboring cells through relative narrow-band transmit power messages, adjusting their downlink resource power levels accordingly to mitigate interference, with cells that do not cause or receive significant interference maintaining current power levels and those that do participating in inter-cell interference coordination by reducing power on specific resource blocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If FFR partitions cell bandwidth to protect cell-edge users from interference, then cell-edge rate and coverage improve, but network throughput and spectral efficiency deteriorate
Solution Approach 1:
The patent applies local quality by differentiating interference coordination treatment between cell-edge users and cell-interior users. Cell-edge users receive enhanced protection through selective ICIC participation and power reduction on specific resource blocks, while cell-interior users maintain normal service without unnecessary power reductions. This localized differentiation resolves the contradiction by improving cell-edge reliability only where needed rather than applying blanket power reductions across the entire network.
Solution Approach 2:
The patent segments the network into different ICIC participation categories: fully participating cells, non-participating cells, and partially participating cells. This segmentation allows selective application of interference coordination measures only where interference problems exist, rather than uniformly across all cells. By dividing the network into these segments, the system improves cell-edge coverage in problematic areas while maintaining high throughput in areas without interference issues.
2Reliability
If cells reduce power on downlink resources to mitigate interference, then cell-edge user signal-to-noise ratio improves, but network capacity and spectral efficiency worsen
Solution Approach 1:
The patent dynamically changes power parameters based on interference conditions. Cells adjust their downlink power levels on specific resource blocks selectively - reducing power only when interference coordination is needed and maintaining normal power levels when interference is not an issue. This dynamic parameter adjustment resolves the contradiction by optimizing signal-to-noise ratio only where necessary rather than applying uniform power reduction.
Solution Approach 2:
The patent applies partial action by having only certain cells participate in ICIC power reduction rather than all cells. Cells that are determined to be non-interfering or non-interfered do not participate in power reduction, while only cells with actual interference problems apply power reduction on specific resource blocks. This partial application of power reduction improves SNR where needed while minimizing the impact on overall network capacity.
3Object-affected harmful factors
If all cells participate in ICIC power reduction, then inter-cell interference decreases, but unnecessary power reductions occur in non-interfering cells
Solution Approach 1:
The patent enables cells to self-determine their ICIC participation status by evaluating their own interference characteristics and neighboring cell conditions. Each cell autonomously decides whether to participate in power reduction based on local interference measurements and messages from neighboring cells, rather than receiving top-down directives. This self-service mechanism ensures that only cells with actual interference problems reduce power, eliminating unnecessary energy loss in non-interfering cells while still achieving interference mitigation where needed.
Data Source
AI summary
An example method is provided in one example embodiment and includes receiving a first message indicative of whether a first cell is non-interfering to at least one neighboring cell, determining whether the first cell is non-interfering to the at least one neighboring cell based upon the first message, and responsive to a determination that the first cell is not non-interfering to the at least one neighboring cells, reducing a power level of one or more downlink resources of a fractional frequency reuse portion of a frequency spectrum associated with the first cell.