Sub-channel Power Boost for LTE Cell Edge Coverage
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Solution Overview
Problem
LTE cellular communications networks face a trade-off between high spectrum efficiency and coverage, as a small frequency reuse factor enhances spectrum efficiency but worsens coverage due to increased out-of-cell interference, while a high frequency reuse factor improves coverage but reduces spectrum efficiency.
Innovation Solution
The base station determines if a power boost is needed for the communications link and uses a subset of sub-carrier frequencies to create a reduced bandwidth channel, concentrating signal power and improving SINR, especially for user devices at cell edges, thereby enhancing coverage without compromising spectrum efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a small frequency reuse factor (N=1) is used to achieve high spectrum efficiency, then spectrum efficiency is improved, but out-of-cell interference increases and coverage deteriorates
Solution Approach 1:
The patent applies local quality by differentiating transmission power across different spatial locations. Specifically, it identifies cell edge regions where coverage is problematic and applies enhanced power boosting only in those local areas rather than uniformly across the entire cell. This allows the system to maintain N=1 frequency reuse for high spectrum efficiency while providing targeted coverage enhancement where interference is most problematic.
Solution Approach 2:
The patent changes the power parameter dynamically based on channel conditions and user device location. It adjusts transmission power by selecting subsets of sub-carrier frequencies and applying power boosting factors to specific resource blocks allocated to cell edge users. This parameter change enables the system to overcome the coverage limitation of N=1 frequency reuse without sacrificing overall spectrum efficiency.
2Reliability
If a high frequency reuse factor (N>1) is used to improve coverage by decreasing out-of-cell interference, then coverage is improved, but spectrum efficiency decreases
Solution Approach 1:
Instead of changing the frequency reuse factor parameter, the patent changes the power distribution parameter across frequency resources. It maintains N=1 frequency reuse but compensates for interference by applying power boosting to specific sub-carrier subsets for cell edge users, thereby achieving coverage improvement without the spectrum efficiency penalty of higher frequency reuse factors.
3Productivity
If signal power is spread across the full channel bandwidth to maintain spectrum efficiency, then spectrum efficiency is maintained, but SINR at cell edges becomes too low for reliable communication
Solution Approach 1:
The patent applies local quality by concentrating signal power on specific local frequency resources (subsets of sub-carrier frequencies) rather than uniformly spreading power across the entire bandwidth. This localized power concentration improves SINR for cell edge users on their allocated resource blocks while maintaining overall spectrum efficiency through efficient resource allocation.
Solution Approach 2:
The patent segments the frequency bandwidth into multiple resource blocks and further divides them into subsets for different users. By allocating specific subsets of sub-carrier frequencies to cell edge users and applying power boosting to those specific segments, the system achieves both high SINR for vulnerable users and maintains overall spectrum efficiency through efficient frequency resource utilization.
Data Source
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AI summary
A method and system are provided for boosting power for a communications link between a base station and a user device, or user equipment, in a cellular communications network. In one embodiment, the communications link is a downlink between the base station and the user device established via a downlink channel having a full channel bandwidth including a number of sub-carrier frequencies. The base station determines whether a power boost is needed for a downlink to the user device. If so, the base station uses a subset of the sub-carrier frequencies from the full channel bandwidth as a reduced bandwidth channel, or sub-channel, for the downlink to the user device such that signal power is concentrated on the sub-carrier frequencies of the reduced channel bandwidth rather than spread across the sub-carrier frequencies of the full channel bandwidth. As a result, a power boost for the downlink is provided.