Simulation and Measurement Studies of The Vdes System’s Terrestrial Component

Abstract

In the paper, the measurement and simulation results of the VDES (VHF Data Exchange System) terrestrial component are discussed. It is anticipated that VDES will be one of the major solutions for maritime communications in the VHF band and its performance will be sufficient to fulfill the requirements of the e-navigation applications. The process of the VDES standardization (ITU R, IALA) has not been officially completed yet, but substantial amount of technical information about the future system’s terrestrial component (VDE-TER) is already available. The paper is divided into three general parts: (a) theoretical presentation of the system’s physical layer and the radio channels applicable to VDES, (b) simulation results (BER, BLER, channel delay between two propagation paths and its influence on bit rates) and (c) measurement results (useful ranges, BER). It turned out that in real maritime conditions, the VDES system can offer ranges between 25 and 38 km for the configurations assumed during the measurement campaign. Those results are generally compliant with the theoretical data in the line-of-sight conditions. In the NLOS scenarios, where fading becomes the dominant phenomenon, the discrepancies between the measurements and the theoretical results were more significant. The obtained results confirmed that VDES provides a large coding gain, which significantly improves the performance of data transmission and increases the bit rate compared to the existing maritime radiocommunication solutions. It should be noted that the results presented in the article were used by the IALA while developing the current version of the VDES specification.

Ranging and Positioning Accuracy for Selected Correlators under VHF Maritime Propagation Conditions

“…After the selection of the correlators, a full test campaign was performed on a π/4-QPSK signal generated by the VHF data exchange system (VDES) [13], [14] software simulator [15]. For testing purposes, a second signal was generated by shifting half of the sample from the first signal and by adding low-power noise.…”

Concept, signal design, and measurement studies of the R‐mode Baltic system

“…The physical layers of the AIS (ITU‐R, 2014) and VDES (ITU‐R, 2015) were implemented in the software for USRP platform. In case of the VDES system implementation, the main changes with respect to the AIS system were the utilization of the π/4‐QPSK modulation (instead of GMSK) and the root raised cosine (RRC) filter with a roll‐off factor = 0.3 for the 100 kHz band (Bronk et al., 2019a; IALA, 2019; ITU‐R, 2015). The latter is used to reduce the modulated signal bandwidth and to minimize the intersymbol interference (ISI).…”

Radio Channel Modelling for VHF System Operating in the Offshore Wind Farms Propagation Environment

“…This creates the need to analyze and evaluate the impact of the emerging offshore turbines on critical radiocommunication systems. In the case of offshore wind farms, the most important frequency range in the context of such analysis is definitely the so-called maritime VHF band (156-174 MHz), because it is utilized by most of the safety-and navigation-related systems (including AIS [2,3], GMDSS, VDES [4][5][6], and many other systems ensuring safety, security, and monitoring of shipping) operated by maritime administrations, navy, border guard, coastal guard, etc. (to a lesser extent, the medium frequency is also relevant to such analysis).…”