Interference Cancellation in LOS MIMO Clock Regeneration
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Solution Overview
Problem
In communication networks, especially in Line Of Sight (LOS) MIMO systems, symbol clock generation is challenging due to equal signal levels at receiver antennas, leading to large clock jitter and potential lack of synchronization if not properly managed.
Innovation Solution
The interference cancellation process is split into two parts: a first part before adaptive filtering and a second part after filtering, with the majority of cancellation occurring before symbol clock regeneration, using a canceling unit and filtering unit within a communication node to improve interference cancellation and reduce clock timing effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If interference cancellation is performed after adaptive filtering, then filtering precision is improved, but clock jitter increases and synchronization reliability deteriorates
Solution Approach 1:
The interference cancellation process is segmented into two distinct stages: pre-filtering cancellation and post-filtering cancellation. The pre-filtering cancellation stage processes signals before adaptive filtering to maintain clock synchronization reliability, while the post-filtering cancellation stage processes residual interference after adaptive filtering to achieve high filtering precision. This segmentation allows each stage to optimize for its specific function without compromising the other.
2Reliability
If majority of cancellation occurs before symbol clock regeneration, then clock jitter is reduced and synchronization is improved, but filtering precision may be compromised
Solution Approach 1:
The interference cancellation process continues across both pre-filtering and post-filtering stages, ensuring continuous suppression of interference. The pre-filtering stage addresses the majority of interference to protect clock synchronization, while the post-filtering stage continues the cancellation process to eliminate residual interference, maintaining continuous useful action throughout the signal processing chain.
3Reliability
If CLR-PLL bandwidth is increased, then clock regeneration performance is improved, but interference from multiple signals increases
Solution Approach 1:
Interference cancellation is performed as a preliminary action before the signals enter the CLR-PLL. By removing the majority of interference from multiple signals before clock regeneration, the CLR-PLL can operate with higher bandwidth and improved performance without being overwhelmed by excessive interference. This preliminary cleanup enables the PLL to function more effectively.
Data Source
AI summary
The present solution relates to a method in a communication node (201, 204, 210, 213) for canceling interference between a plurality of signals in a communication system (200). The communication node receives (501), at each of a plurality of receiver antennas (407), a respective signal. The communication node (201, 204, 210, 213) cancels (502) a first part of interference between the plurality of received signals. Then, the interference cancelled signals and the received signals are filtered (504) before a second part of interference between the filtered signals is cancelled (505).