Ship-Centric Direct Communication with Pilot-Aided Fading Compensation

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Solution Overview

Problem

Existing maritime communication systems face challenges with high power consumption, interference, and multipath fading due to sea level effects when using high-frequency bands, especially in maritime environments, which are not adequately addressed by current technologies like SC-FDE and OFDM.

Innovation Solution

A ship-centric direct communication system utilizing a transmission frame with strategically placed pilots for channel estimation and linear interpolation in the frequency domain, combined with a pseudo-random noise sequence to reduce power density and enhance modulation efficiency, minimizing multipath fading impacts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If high-frequency bands are used for maritime communication, then data transmission rate is improved, but multipath fading caused by sea level effects worsens

Engineering Contradiction:

Improvedata transmission rateVSAvoidsignal quality

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies SC-FDE modulation which transforms the signal from time domain to frequency domain for processing, changing the parameter of signal representation. This frequency domain equalization effectively combat multipath fading by compensating for channel effects on each frequency component independently, thus maintaining signal quality at high data rates

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces frequency domain equalization as an intermediary process between transmission and reception. The equalizer acts as a mediator that compensates for multipath fading effects by calculating and applying inverse channel responses in the frequency domain, thereby restoring signal quality without reducing transmission rate

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If OFDM method is used for downlink transmission, then spectral efficiency is improved, but peak-to-average power ratio increases causing transmitter power inefficiency

Engineering Contradiction:

Improvespectral efficiencyVSAvoidtransmitter power consumption

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

Instead of using OFDM's multiple orthogonal subcarriers in time domain, the patent inverts the approach by using single carrier frequency domain equalization. The data is first modulated on a single carrier, then transformed to frequency domain for equalization, and finally transformed back. This inversion maintains spectral efficiency while avoiding the high PAPR problem of OFDM

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent replaces the time-domain equalization mechanism with a frequency-domain equalization mechanism. Instead of dealing with complex time-domain channel impulse responses, the system substitutes this with simpler frequency-domain channel transfer functions that are easier to equalize, reducing the computational and power burden on the transmitter

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If pilots are transmitted frequently for channel estimation in fast-moving environments, then channel estimation accuracy is improved, but overhead increases reducing actual user transmission speed

Engineering Contradiction:

Improvechannel estimation accuracyVSAvoiduser transmission speed

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent uses frequency domain sampling to estimate the channel response at all frequency points based on measurements at selected pilot frequency points. This partial action approach allows accurate channel estimation across the entire bandwidth by interpolating from a subset of pilot measurements, reducing overhead while maintaining accuracy in fast-moving environments

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS12520339B2Ship-centric direct communication system and operation method thereof

Publication Date: 2026.01.06 KOREA INSTITUTE OF OCEAN SCIENCE & TECHNOLOGY

AI summary

A ship-centric direct communication system and an operation method thereof are proposed. The system includes a data transmission device configured to transmit, to a data reception device through a link channel, a transmission frame composed of a plurality of slots generated according to slot time, a plurality of pilots provided for channel estimation and arranged at respective specific positions in each of the plurality of slots according to a pilot transmission period, and data symbols arranged between each of the plurality of pilots, and the data reception device configured to perform channel compensation for data present between the plurality of pilots by using the plurality of pilots for each of the plurality of slots of the transmission frame when the transmission frame is received from the data transmission device and performing linear interpolation after the channel estimation in a frequency domain, and convert channel-compensated signals back into time domain symbols.