Multicast Precoding for Multi-Beam Satellite Systems
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Solution Overview
Problem
High inter-beam interference in multi-beam satellite communication systems due to aggressive frequency reuse limits the effectiveness of spectrum utilization, requiring advanced precoding techniques to manage channel state information and interference across multiple user terminals.
Innovation Solution
A method for multicast precoding in multi-user multiple-input multiple-output (MU-MIMO) satellite communication systems, where terminal subgroups are selected based on channel state information, and equivalent channel state information is determined to construct a constant precoding matrix, reducing inter-beam interference and improving signal-to-noise-plus-interference ratio (SNIR).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If frequency reuse is increased to improve system capacity, then spectrum utilization is improved, but inter-beam interference increases
Solution Approach 1:
The patent applies preliminary anti-action by calculating precoding matrices that pre-compensate for inter-beam interference before signal transmission. The gateway computes precoding matrices based on channel state information from multiple beams, and these matrices are designed to counteract the expected interference patterns. By applying the precoding matrix to the signal vector before transmission, the system proactively neutralizes interference rather than reacting to it after reception, thereby enabling aggressive frequency reuse while maintaining signal quality.
Solution Approach 2:
The patent converts inter-beam interference from a harmful factor into a beneficial element by using the interference patterns themselves as input for precoding matrix calculation. The channel state information from multiple beams, which contains interference characteristics, is processed to generate precoding matrices that exploit knowledge of the interference environment. This transforms the previously harmful interference into useful information that guides the precoding design, improving overall system performance.
2Reliability
If joint processing (precoding) is implemented to reduce inter-beam interference, then signal quality is improved, but computational complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the set of beams into multiple subsets and calculating separate precoding matrices for each subset rather than computing a single precoding matrix for all beams simultaneously. This segmentation reduces the dimensionality of the computational problem at any given time, making the joint processing more tractable while still achieving interference mitigation within each subset. The gateway can process beams in manageable groups, reducing peak computational complexity.
Solution Approach 2:
The patent implements dynamics by adaptively adjusting the precoding strategy based on current channel conditions and system state. The precoding matrices are calculated dynamically using current channel state information from terminals, allowing the system to optimize performance for varying interference patterns and traffic conditions. This dynamic adaptation enables the system to achieve high signal quality when needed while potentially reducing computational effort when conditions are more favorable.
3Measurement precision
If channel state information is collected from all terminals to enable precoding, then precoding accuracy is improved, but feedback overhead increases
Solution Approach 1:
The patent applies segmentation to feedback by collecting channel state information from terminals in a segmented manner corresponding to beam subsets. Rather than requiring all terminals to feedback simultaneously or process all beam information at once, the system organizes feedback collection and processing by subsets, reducing the instantaneous feedback overhead while maintaining sufficient channel state information accuracy for effective precoding within each subset.
Data Source
AI summary
A, method and apparatus for wirelessly transmitting data to a plurality of terminals in each of a plurality of beams through a plurality of transmit feeds includes selecting, for each beam, two or more terminals among the plurality of terminals in the beam as a subgroup of terminals, on the basis of channel state information of the plurality of terminals; determining, for each beam, equivalent channel state information representing the subgroup of terminals in the beam on the basis of the channel state information of the terminals of at least one of the plural subgroups of terminals; and determining a set of weight coefficients that relate the plurality of transmit feeds to a plurality of signals that are intended for transmission in the plurality of beams on the basis of the equivalent channel state information representing the plural subgroups of terminals. Also disclosed is a method and apparatus for receiving data transmitted via wireless transmission to a plurality of beams through a plurality of transmit feeds and estimating a channel on the basis of the received data. The present disclosure is advantageously applicable to satellite communication systems.