Small Cell Uplink Interference Mitigation via Preamble Correlation
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Solution Overview
Problem
Current mechanisms for mitigating uplink interference between macrocell and small cell base stations are inadequate when there is an imbalance in downlink and uplink coverage, making it difficult to identify and address interference caused by macrocell user equipment (UEs) that do not detect the small cell's downlink signal.
Innovation Solution
The method involves transmitting preambles from potentially interfering UEs to a small cell, which then reports back to the macrocell base station, allowing the macrocell to identify and mitigate interference by correlating preamble detection with UE locations and signal strengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If small cells operate within macrocell coverage area using the same radio carrier, then network capacity and service uniformity are improved, but co-channel interference between cells increases
Solution Approach 1:
The patent segments the carrier resources by dividing subcarriers into different groups allocated for cell-center UEs and cell-edge UEs. Small-cell UEs are served using subcarriers allocated for macrocell UEs near the center, while macrocell UEs near the edge use dedicated subcarriers. This segmentation reduces co-channel interference while maintaining network capacity.
Solution Approach 2:
The patent applies local quality by allocating different subcarrier resources to different spatial locations and UE types. Cell-center UEs and small-cell UEs receive different subcarrier allocations than cell-edge UEs, creating location-specific resource quality that mitigates interference in specific areas while preserving overall network productivity.
2Adaptability or versatility
If small cells use subcarriers allocated for macrocell UEs near the edge, then resource utilization is improved, but uplink interference to small cell increases
Solution Approach 1:
The patent segments subcarrier allocation into distinct groups: one group for small-cell UEs and cell-center macrocell UEs, and another group for cell-edge macrocell UEs. This segmentation prevents macrocell UEs near the edge from interfering with small-cell uplink transmissions while maintaining efficient carrier utilization through targeted resource allocation.
3Object-affected harmful factors
If macrocell UEs near the edge are separated by distance from small-cell UEs, then uplink interference is reduced, but resource allocation flexibility decreases
Solution Approach 1:
The patent segments the macrocell UE population into cell-center and cell-edge groups with dedicated subcarrier allocations. This segmentation naturally separates interfering macrocell UEs from small-cell UEs in the frequency domain, reducing uplink interference while maintaining manageable resource allocation complexity through systematic grouping.
Solution Approach 2:
The patent applies local quality by providing different subcarrier resource allocations to macrocell UEs based on their location (cell-center vs. cell-edge). This location-based resource differentiation reduces interference for small-cell uplink while maintaining flexibility in resource allocation through location-specific quality adjustments.
Data Source
AI summary
Identifying a interfering, candidate or suspect of interfering (interferer) user device, UE, being served by a first base station (macro eNB) and causing uplink interference on a second base station (small cell). The first base station (macro eNB) transmits uplink channel configuration information (PRACH configuration info) to the second base station (small cell). The first base station (macro eNB) receives an Interference indication message, comprising an indication that a cell of the second base station (small cell) is experiencing uplink interference form at least one user device. For each of a plurality of user devices being served by the first base station (macro eNB), the first base station (macro eNB), assigns a preamble to the user device, UE, and transmits the assigned preamble to the user device, UE. The first base station (macro eNB) also transmits the assigned preambles to the second base station (small cell). The first base station (macro eNB) then receives a list of preambles detected at the second base station, and identifies the at least one interfering user device, UE, based on the received list.