Partial OFDM Symbol Filtering for ACLR Compliance
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Solution Overview
Problem
In 3GPP LTE, 4G, and 5G communication systems, the discontinuity between OFDM symbols leads to out-of-band energy leakage, worsening the adjacent channel leakage ratio (ACLR) and requiring extensive Digital Signal Processing (DSP) resources for full channel filtering, which is inefficient.
Innovation Solution
Implementing partial channel filtering that selectively filters only the time domain samples surrounding the points of discontinuity between OFDM symbols, reducing the DSP resources needed while meeting ACLR specifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If full channel filtering is applied to all transmitted time domain samples, then ACLR specification requirements are met, but DSP resources are consumed excessively
Solution Approach 1:
The patent divides the continuous stream of time domain samples into discrete groups, where each group contains samples surrounding a specific OFDM symbol boundary discontinuity. The channel filter is applied selectively to each group independently rather than to the entire signal stream, reducing overall DSP resource consumption while maintaining ACLR compliance at each discontinuity point.
Solution Approach 2:
The patent applies channel filtering only locally around the points of discontinuity (OFDM symbol boundaries) where it is most needed to prevent out-of-band energy leakage. Samples far from discontinuities are not filtered, creating a non-uniform filtering strategy that optimizes the balance between ACLR performance and DSP resource usage.
2Object-generated harmful factors
If channel filtering is applied to all time domain samples, then out-of-band energy leakage is reduced, but processing efficiency decreases
Solution Approach 1:
The patent extracts and identifies the specific portions of the signal that contain discontinuities (OFDM symbol boundaries) and applies filtering only to those extracted segments. By separating the filtering operation from the entire signal processing chain and applying it only where necessary, processing efficiency is improved while still reducing out-of-band energy leakage effectively.
Solution Approach 2:
Instead of applying full channel filtering to all samples (excessive action), the patent applies partial filtering only to the minimal necessary portions of the signal surrounding discontinuities. This partial action approach achieves sufficient suppression of out-of-band energy leakage while dramatically improving processing efficiency.
Data Source
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AI summary
Various communication systems may benefit from improved radio signaling. For example, communication systems may benefit from selective or partial filtering of a radio signal. A method, in certain embodiments, may include analyze at a network entity a radio signal comprising a plurality of orthogonal frequency division multiplexing symbols. The radio signal comprises at least one point of discontinuity between the plurality of symbols. The method may also include filtering a select time domain sample of the radio signal in the plurality of symbols. The select sample surrounds the at least one point of discontinuity. In addition, the method may include replacing the select time domain sample surrounding the at least one point of discontinuity of the radio signal with the filtered sample in the plurality of symbols.