Dynamic Transmit Power Adjustment for Small Cell Coverage Holes
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Solution Overview
Problem
Deploying radio cells in indoor environments is complex due to factors like building layout, propagation characteristics, and interference, making it challenging to achieve optimal coverage while minimizing the number of cells and interference between them.
Innovation Solution
A method for dynamically adjusting downlink transmit power levels of radio nodes in a radio access network by identifying coverage holes based on signal strength and UE connection history, and adjusting power levels accordingly to ensure optimal coverage and reduce interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If radio cells are positioned close enough to each other to obtain optimal coverage, then coverage quality is improved, but interference between radio cells increases
Solution Approach 1:
The patent implements dynamic transmit power adjustment where the network controller continuously monitors coverage hole events and handover events, then adjusts the transmit power of individual radio cells in real-time based on observed conditions. This dynamic approach allows the system to maintain optimal coverage while adapting to changing interference conditions, resolving the contradiction between coverage quality and interference.
Solution Approach 2:
The system employs feedback mechanisms by counting coverage hole events (A2 events) and handover events (A1 events) to infer the presence of coverage holes. Based on this feedback information, the network controller adjusts transmit power levels to eliminate coverage holes while minimizing interference. The closed-loop control ensures that power adjustments are made only when and where necessary.
2Device complexity
If the number of radio cells is reduced to simplify deployment, then device complexity is decreased, but coverage holes increase
Solution Approach 1:
The system enables self-optimization by automatically detecting coverage holes through event counting and autonomously adjusting transmit power levels without requiring manual intervention. This self-service capability allows the network to maintain optimal coverage with fewer cells, reducing deployment complexity while ensuring coverage continuity through automated adaptation.
3Reliability
If downlink transmit power is increased to eliminate coverage holes, then coverage quality is improved, but power consumption and interference increase
Solution Approach 1:
The patent applies local quality by adjusting transmit power specifically for radio cells identified as having coverage holes, rather than uniformly increasing power across the entire network. The network controller identifies specific cells involved in coverage hole events and adjusts only their power levels, thereby eliminating coverage holes while minimizing overall power consumption and limiting interference to affected areas only.
Data Source
AI summary
A method for assigning downlink transmit power levels to radio nodes (RNs) in a small cell radio access network (RAN) includes assigning initial power levels to the RNs. For each cell, first events are counted indicating that UEs receiving a signal from their serving cells with a signal strength below a specified value have entered a coverage hole. For each cell, second events are counted indicating that UEs have re-established a previous connection on one of the cells. For each pair of cells, a coverage hole is identified between them if the number of first events for one cell exceeds a threshold and, a number of second events or re-establishment of a previous connection on the other cell exceeds another threshold. For each identified coverage hole, the downlink transmit power level is increased of at least one RN in the pair of cells between which the coverage hole is identified.