Feeder Link OFDM Waveform Bandwidth Expansion
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Solution Overview
Problem
In 5G wireless systems, the feeder link faces challenges in finding sufficient bandwidth in lower frequency bands to support multiple beams for wide-area coverage, especially when using NR FR1 bands, which are susceptible to phase noise and Doppler-induced distortions, making it difficult to maintain reliable communication.
Innovation Solution
The solution involves multiplexing parallel streams of OFDM symbols into a single stream with a higher sample rate and shorter symbol duration, using a wider subcarrier spacing to occupy a wider bandwidth, and inserting reference signals for synchronization, thereby enhancing robustness against channel distortion and phase noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple beams are used for wide-area coverage on the feeder link, then coverage area is improved, but bandwidth availability deteriorates due to insufficient bandwidth in lower frequency bands
Solution Approach 1:
The patent transitions from using multiple parallel beams in the horizontal dimension to using a single beam with expanded frequency dimension (wider bandwidth). By occupying wider bandwidth through increased subcarrier spacing and higher sample rates, the system achieves wide-area coverage without requiring multiple beams, thus resolving the bandwidth scarcity issue in lower frequency bands.
Solution Approach 2:
The patent changes key parameters of the OFDM waveform including increasing subcarrier spacing, raising sample rate, and shortening symbol duration. These parameter changes enable the single beam to occupy wider bandwidth and achieve wide-area coverage, eliminating the need for multiple beams and resolving the bandwidth availability contradiction.
2Adaptability or versatility
If NR FR1 bands are used on the feeder link, then compatibility with existing networks is improved, but communication reliability deteriorates due to phase noise and Doppler-induced distortions
Solution Approach 1:
The patent modifies critical OFDM parameters including subcarrier spacing, sample rate, and symbol duration to create a more robust waveform. These parameter changes increase the system's resistance to phase noise and Doppler effects while maintaining compatibility with NR FR1 networks, thereby resolving the reliability contradiction.
Solution Approach 2:
The patent incorporates reference signals at strategically positioned intervals within the symbol stream to provide beforehand cushioning against channel distortions. These reference signals enable continuous synchronization and compensation for phase noise and Doppler effects, maintaining communication reliability despite using NR FR1 bands.
3Productivity
If parallel streams of symbols are multiplexed into a single stream with higher sample rate, then bandwidth efficiency is improved, but processing complexity increases
Solution Approach 1:
The patent merges multiple parallel symbol streams into a single multiplexed stream with higher sample rate. This consolidation improves bandwidth efficiency by utilizing the available spectrum more effectively while the standardized multiplexing procedure keeps processing complexity manageable through systematic organization of the combined stream.
Data Source
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AI summary
Systems, methods, apparatuses, and computer program products for feeder link data transport are provided. For example, baseband in-phase and quadrature (IQ) data may be processed at the transmitter and receiver of the feeder link. The orthogonal frequency division multiplexing (OFDM) waveform used in a beam may be modified for transmission over the feeder link. For example, the waveform may have a wider subcarrier spacing (SCS) and may fill an enlarged bandwidth than otherwise with a feeder link.