Link Adaptation Interference Reduction via Scheduling Knowledge
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Solution Overview
Problem
In packet-based wireless communication networks like LTE, existing methods for link adaptation fail to accurately account for interference from uncoordinated transmissions, leading to suboptimal modulation, coding, and power settings, especially for UEs near cell borders, which results in reduced network capacity and increased latency.
Innovation Solution
Implementing a method in radio base stations that uses UE scheduling knowledge to adjust Channel Quality Indicators (CQI) by estimating and correcting for interference from scheduled UEs, thereby selecting a suitable link adaptation scheme that includes coding rate, modulation, and transmit power, while maintaining a noise margin to minimize retransmissions and interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If link adaptation is performed based on reported and measured CQI and received power level, then the transmission can be adapted to current interference situation, but the interference experienced in the past will not be the same as the interference present in the scheduled time frame, leading to suboptimal modulation, coding, and power settings
Solution Approach 1:
The patent applies preliminary action by predicting future interference levels based on scheduled transmissions before actually performing the link adaptation. The base station calculates expected interference from newly scheduled UEs and adjusts CQI accordingly, so that the link adaptation decisions are made with knowledge of upcoming interference conditions rather than relying solely on past measurements.
Solution Approach 2:
The patent implements feedback by using the scheduled transmission information as a feedback mechanism to adjust CQI predictions. The base station feeds back the expected interference impact from scheduled UEs to the link adaptation process, creating a closed-loop system where scheduling decisions inform interference estimation, which in turn guides modulation and coding selections.
2Area of stationary object
If UEs near cell borders are served, then network coverage is improved, but these UEs are very sensitive to interference from other UEs in adjacent cells and radio base stations, requiring accurate interference knowledge for power allocation
Solution Approach 1:
The patent applies local quality by treating interference management differently for cell border UEs versus other UEs. The system specifically calculates and applies interference adjustments for UEs identified as being near cell borders, recognizing that these UEs have different interference characteristics and require specialized handling in the link adaptation process.
3Productivity
If interference from scheduled UEs is not accounted for in link adaptation, then the scheduling process remains simple, but this leads to reduced network capacity and increased latency
Solution Approach 1:
The patent applies self-service by having the base station automatically calculate and adjust CQI based on its own scheduling decisions. The base station uses its knowledge of scheduled UEs to predict interference and adjust link adaptation parameters without requiring additional signaling or external input, making the interference management self-contained within the base station's scheduling logic.
Data Source
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AI summary
The present invention relates to a method and arrangement for reducing interference in a cellular communication network. A radio base station of the network is configured to serve at least a first cell, where interference is reduced by selecting a link adaptation scheme for a UE in the first cell, The arrangement comprises means for receiving measurements on estimated channel quality, means for estimating channel quality for a future transmission by adjusting the received measurements on estimated channel quality based on knowledge of future UE scheduling in at least the first cell, and means for selecting the link adaptation scheme comprising a transmit power level based on the estimated channel quality for the future transmission.