Fronthaul Frequency-Domain Compression via IDFT Dynamic-Range Reduction

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Solution Overview

Problem

Conventional radio fronthaul interface compression techniques are inefficient due to the large dynamic range of frequency domain data, which affects compression and decompression performance, especially in scenarios with power control, high-order modulation, and user multiplexing.

Innovation Solution

Applying Inverse Discrete Fourier Transform (IDFT) to frequency domain data to reduce the dynamic range, allowing for compression in the time domain, and then transmitting the compressed signal over the fronthaul interface, where it can be decompressed and transformed back to frequency domain using Discrete Fourier Transform (DFT) at the remote unit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If compression is applied directly to frequency domain data, then bandwidth efficiency is improved, but compression performance deteriorates due to large dynamic range

Engineering Contradiction:

Improvebandwidth efficiencyVSAvoidcompression performance

Core Design Contradiction:

Loss of energyVSMeasurement precision

Solution Approach 1:

The patent changes the domain parameter from frequency domain to time domain for compression. By applying IDFT to convert frequency domain data to time domain signal, the dynamic range is reduced, enabling better compression performance while maintaining bandwidth efficiency.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces IDFT and DFT transforms as intermediary operations. The IDFT at the transmitting end converts frequency domain data to time domain signal for compression, and the DFT at the receiving end converts the decompressed time domain signal back to frequency domain, serving as mediators to resolve the dynamic range issue.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If dynamic range of frequency domain signal is reduced, then compression performance is improved, but signal processing complexity increases

Engineering Contradiction:

Improvecompression performanceVSAvoidsignal processing complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #35Parameter changes

3Reliability

If separate fiber is run to each radio unit, then signal quality is maintained, but cost increases

Engineering Contradiction:

Improvesignal qualityVSAvoidcost

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent merges multiple radio unit data streams into a single fronthaul connection by converting to time domain, compressing, and transmitting over shared Ethernet infrastructure. This combining approach reduces the quantity of fiber required while maintaining signal quality through effective compression.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent replaces the physical mechanical system of separate fiber connections with a logical multiplexing system using Ethernet and compression algorithms. This substitution allows multiple connections to share physical infrastructure while maintaining the functional equivalence of dedicated connections.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS10135599B2Frequency domain compression for fronthaul interface

Publication Date: 2018.11.20 NOKIA TECHNOLOGIES OY

AI summary

Frequency domain compression of fronthaul interface for transporting frequency domain data over Ethernet includes applying Inverse Discrete Fourier Transform to frequency domain data contained in a frequency bandwidth to generate a time domain output signal in a time domain. The time domain output signal is compressed to generate a compressed time domain output signal. The compressed time domain output signal is transmitted over a fronthaul interface to a remote unit. The compressed time domain output signal is decompressable at the remote unit to generate a decompressed time domain output signal. Discreet Fourier Transform is applied to the decompressed time domain output signal at the remote unit to recover the frequency domain data.