Massive MIMO Precoding Interference Mitigation
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Solution Overview
Problem
In Massive MIMO systems, downlink precoding operations cause significant interference to neighboring cells, particularly due to SRS contamination, as the precoding vectors between serving and neighboring cells can be parallel, leading to increased interference.
Innovation Solution
A method is introduced where the serving cell identifies and notifies interfering cells about specific RS ports causing interference through backhaul signaling, allowing the interfering cells to adjust their precoding vectors to minimize interference. This involves configuring and transmitting RS ports using multiple antennas and determining orthogonal precoding matrices based on feedbacked CSI and SRS information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If downlink precoding operation is performed in Massive MIMO system, then system capacity increases and transmitting power decreases, but interference to neighboring cells increases significantly
Solution Approach 1:
The patent applies local quality by making the precoding operation selective rather than uniform across all cells. The serving cell performs precoding to improve its own performance, while neighboring cells are identified and excluded from precoding operations in the affected resource elements. This localized differentiation resolves the contradiction by allowing precoding benefits in the serving cell while preventing interference propagation to neighboring cells.
Solution Approach 2:
The patent inverts the conventional approach by having the serving cell identify and protect neighboring cells from interference rather than having neighboring cells try to avoid interfering with each other. The serving cell determines which resource elements cause interference to neighboring cells and selectively applies precoding only where it benefits the serving cell without harming neighbors, thus solving the interference problem from the source rather than the destination.
2Power
If precoding vectors of serving cell and neighboring cell are parallel, then Massive MIMO gain is achieved, but SRS contamination increases
Solution Approach 1:
The patent applies preliminary action by having the serving cell proactively identify neighboring cells that may suffer from SRS contamination before the contamination occurs. The serving cell determines which resource elements would cause parallel precoding vectors with neighboring cells and pre-selects alternative resource elements or adjusts precoding configurations to avoid the contamination, thus preventing the harmful effect rather than correcting it afterward.
3Object-generated harmful factors
If interference cancellation scheme is implemented, then interference to neighboring cells is reduced, but device complexity increases
Solution Approach 1:
The patent applies self-service by having the serving cell autonomously identify and resolve its own interference issues without requiring complex coordination with neighboring cells. The serving cell independently determines which resource elements cause interference, selects alternative resource elements, and adjusts its precoding operations accordingly. This self-contained approach reduces interference while avoiding the complexity of inter-cell coordination mechanisms.
Data Source
AI summary
The present invention provides a large-scale MIMO communication method and device in a base station and a UE. In one embodiment, a base station transmits first signaling firstly, wherein the first signaling indicates the configuration information of a first RS, and the first RS includes M RS ports; and then receives second signaling, wherein the second signaling indicates M1 RS ports in the first RS, M is a positive integer greater than 1, M1 is a positive integer smaller than or equal to M, and transmitting cells of the first RS are cells other than transmitting cells of the first signaling. The present invention effectively reduces interference with neighboring cells during Massive MIMO transmission, and solves the problem of SRS contamination. Meanwhile, the present invention is compatible with the existing LTE system as much as possible and has good compatibility.