Development and test of a trans-horizon communication system based on a MIMO architecture

Abstract

A multiple-input multiple-output (MIMO) system for trans-horizon radio communications within the high-frequency (HF) band (3 to 30 MHz) is presented. The diversity of transmitted polarizations is proposed as an alternative to spatial diversity in order to limit the aperture of antenna arrays at both ends of the radio link. In a theoretical step providing the estimation of capacity gain for different MIMO architectures, a 2 × 2 MIMO solution transmitting two complementary circular polarizations is identified as a balanced trade-off between performance increase and complexity. The design of the corresponding system is described with a focus on antenna arrays and the kind of signal processing that should be implemented. This novel communication system has been tested on a 280-km-long radio link. The first results underline a data transfer rate reaching a value of 24.09 kbps (in a 4.2-kHz bandwidth) that significantly exceeds the current standards for HF modems.

Hf Skywave Polarized Mimo Channels With Oblique One-Hop Paths

“…On the other hand, for each receive antenna the power contributions from the two transmit antennas tend to be equal. These observations have not been pointed out in [14] but are in line with the result in [13]. (iii) The experimental proof that on average the capacity improvement factor (CIF) of the oblique skywave MIMO channels over SISO channels is lower than the CIF of the NVIS MIMO channels, owing to the lower orthogonality of the cross-dipoles for waves with oblique trajectories.…”

“…In the last decade, researchers have recognized the importance of the characteristic waves, the extraordinary (X) and ordinary (O), that in general are elliptically polarized with opposite senses, in realizing polarization diversity and HF skywave MIMO communications without the need of large spacing between antennas [7][8][9][10][11][12][13][14]. While [7][8][9][10] discover, by simulation and experiment, a lower correlation among subchannels and a greater capacity gain over SISO channels when an antenna structure with two complementary circular polarizations is used compared to a system with linearly polarized antennas, [14] shows mathematically that linearly-polarized antennas can achieve polarization diversity.…”

Radio communication via Near Vertical Incidence Skywave propagation: an overview

“…Using modern means to generate and receive dual circular polarization [123], characteristic wave propagation may be used to provide increased diversity gain [124,125]. NVIS characteristic wave MIMO systems have been proposed by Ndao et al [126]. An overview of the net throughput, bandwidth and SNR in a fading channel of several transmission systems is given in Table 1 for comparison.…”

Antenna selection in a SIMO architecture for HF radio links

“…Future work will compare the degrees of diversity provided by the selected SIMO structure with its extension to a MIMO system that we previously proposed in Ndao et al []. In particular, the possibility of an increased throughput under the constraint of equal transmit power needs to be investigated.…”

“…Further investigations indicate that an increase in the number of antennas results in an increase in the capacity gain, but with moderate relative variations: maximum capacity gain equal to 3.82 for NC = 3, and 4.31 for NC = 4. Future work will compare the degrees of diversity provided by the selected SIMO structure with its extension to a MIMO system that we previously proposed in Ndao et al [2013]. In particular, the possibility of an increased throughput under the constraint of equal transmit power needs to be investigated.…”