Downlink Interference Alignment via Local Channel Knowledge
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Solution Overview
Problem
Existing interference alignment schemes in wireless communication systems require perfect global channel knowledge, are sensitive to channel estimation and quantization errors, and antenna configuration, and are affected by mobility, leading to high feedback overhead and coordination complexity.
Innovation Solution
A low-complexity interference alignment scheme that aligns interference without requiring perfect global channel knowledge, using local channel knowledge at nodes, where each transmitter only needs to know the channel state information for its affiliated receivers, and each receiver projects cross-channel interference onto a predetermined vector to maximize interference-free space for signal transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional interference alignment schemes are used to improve throughput performance, then interference is aligned and degrees of freedom are maximized, but perfect global channel knowledge is required leading to high feedback overhead
Solution Approach 1:
The patent segments the channel knowledge requirement into local components only. Each transmitter needs to know only its own channel to its affiliated receivers and the interfering channel from the other transmitter, rather than requiring complete global channel state information. This segmentation reduces the feedback overhead while still enabling interference alignment through local precoding design.
Solution Approach 2:
The patent applies local quality by having each transmitter use only locally available channel knowledge for precoding design. Each transmitter independently designs its precoding matrix based on local channel estimates, eliminating the need for centralized global channel knowledge and reducing feedback requirements while maintaining interference alignment performance.
2Measurement precision
If traditional interference alignment schemes are used to improve interference alignment accuracy, then interference is concentrated into fewer dimensions, but the schemes are highly sensitive to channel estimation and quantization errors
Solution Approach 1:
The patent applies partial action by not requiring perfect channel knowledge. Instead of demanding complete and accurate global channel state information, the scheme uses partial local channel knowledge to achieve sufficient interference alignment. This relaxed approach reduces sensitivity to estimation and quantization errors while still concentrating interference into fewer dimensions.
3Object-affected harmful factors
If existing interference alignment schemes are applied to manage interference between base stations, then interference effect is decreased, but coordination complexity and feedback overhead increase significantly
Solution Approach 1:
The patent enables self-service operation where each transmitter independently designs its precoding matrix using only locally available channel knowledge. Each base station autonomously manages its own interference without requiring complex coordination with other base stations, thereby reducing coordination complexity and feedback overhead while still decreasing the interference effect through local interference alignment.
Data Source
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AI summary
In the field of wireless communications, a method, system and device are provided for interference alignment on a downlink. The system uses a predetermined vector and channel knowledge from each transmitter to compute and feed back equivalent channel vector information from each receiver to its affiliated transmitter. With this information, each transmitter selects a set of affiliated receivers and constructs a transmitted signal by applying a selected precoding vector to rank 1 data, thereby eliminating interference to certain non-affiliated receivers.