Li-Fi Scrubs Into the Operating Room

IEEE Spectrum  March 13, 2020 An international team of researchers (Germany, Czech Republic) set up multiple Li-Fi transmitters and receivers in a neurosurgery operating room in Prague. In a series of tests, the Li-Fi system managed to transfer data quickly and without complete signal loss. They achieved data rates of up to 600 megabits per second. Because Li-Fi uses higher-frequency light than Wi-Fi does, it could, in theory, have a higher bandwidth and therefore transmit data more quickly. Unlike Wi-Fi’s radio frequencies, which can pass through walls, optical light is easily blocked by humans or objects. To get around this […]

New Antenna Will Boost UAV Communication with Satellites

IEEE Spectrum  March 10, 2020 Conventional sabre-like antennas generate a donut-shape radiation pattern, which provides an omnidirectional coverage and is ideal for air-to-ground communication. However, a donut-shape pattern has a null at its zenith which inhibits communication with other satellites. To provide signal directly above the antenna researchers in China designed a novel sabre-like antenna incorporated two metal radiators into the design. The first is a monopole, which is perpendicular to the ground with an omnidirectional pattern. The second is a dipole, which is parallel to the ground with broadside pattern – creating a signal that fills the blind spot […]

Team develops optical communications technology to double data transfer speed

Phys.org  February 24, 2020 Researchers in South Korea have designed real-time pulse amplitude modulation-4 (PAM-4) digital signal processing including forward error correction for a C-band inter-datacenter network. The PAM-4 DSP is intended to compensate for chromatic dispersion and provide dispersion tolerance. A decision feedback equalizer and maximum likelihood sequence equalizer were employed for the dispersion compensation. A low-density parity check code was used to increase coding gain. They have empirically proved the feasibility of 25 km transmission without error-floor sign, corresponding to a dispersion compensation capacity of 425 ps/nm and confirmed 35 km ∼ 85 km error-free transmission for inter-datacenter […]

Using sound and light to generate ultra-fast data transfer

Science Daily  February 11, 2020 To be able to send data at increased speeds, the lasers need to be modulated very rapidly: switching on and off or pulsing around 100 billion times every second. Instead of using external electronics, researchers in the UK used acoustic waves to vibrate the quantum wells inside the quantum cascade laser. The acoustic waves were generated by the impact of a pulse from another laser onto an aluminium film that caused the film to expand and contract, sending a mechanical wave through the quantum cascade laser. They were able to control the light output by […]

Building an Orbiting Internet Just for Satellites

IEEE Spectrum  January 23, 2020 Small satellites in the low earth orbit depend on NASA’s Tracking and Data Relay Satellite System (TDRSS) to route signals from satellites to the correct ground stations when the satellite is on the other side of the earth. TDRSS is rarely accessible to companies, prohibitively expensive to use, and over 25 years old. To alleviate these problem a company in the US is creating a commercial replacement for TDRSS by building a constellation of many tiny satellites in LEO. The satellites will form the backbone of a space-based mesh network operating much like an Internet […]

Satellite constellations harvest energy for near-total global coverage

Science Daily  January 10, 2020 A team of researchers in the US (Industry, UC Davis, Cornell University) has discovered two alternative 4-satellite constellations with 24- and 48-hour periods, both of which attain nearly continuous global coverage. They harness energy from nonlinear orbital perturbation forces (e.g., Earth’s geopotential, gravitational effects of the sun and moon, and solar radiation pressure) to reduce their propellant and maintenance costs. The 24-hour period constellation reduces the overall required vehicle mass budget for propellant by approximately 60% compared to a geostationary Earth orbit constellation with similar coverage over typical satellite lifetimes. The discovery could drive advances […]

Soundwaves carry information between quantum systems

Nanowerk  December 30, 2019 An international team of researchers ( USA- University of Chicago, UC Santa Barbara, Argonne National Laboratory, Japan) created a hybrid quantum system that acoustically drives transitions in electron spins. The experiment showed a basis for mechanical (strain) control. They developed a theoretical model from a combination of direct experimental observation and density functional theory calculations. From all of this information, they illustrated different types of mechanical strain that drive longer-lasting spins. The material studied was silicon carbide, which has been shown recently to support long-lived spin states that can be accessed optically. The results offer theoretical […]

New system transmits high-speed unrepeated signal over 520 kilometers

EurekAlert  December 16, 2019 To make long-haul data transmission cheaper an international team of researchers (Russia, USA industry) developed transmission line with three sections, each consisting of fiber optic cables of two types connected in series. Remote optically pumped erbium amplifiers (ROPA) were installed at the points of junction between the sections. The systems amplify the signal along the link without the need for electrical power sources. They successfully transmitted a signal over 520 km (323 mi) at 200 Gbps. To avoid the attenuation of the signal, it was amplified initially upon transmission and then two more times remotely, along […]

Communications device offers huge bandwidth potential

EurekAlert  December 10, 2019 Researchers at the University of Illinois have demonstrated that the device they developed can rapidly switch functionality to perform the varied tasks needed to support a network with carrier frequencies of over 100 gigahertz. They developed a 3D-printed scaffold, which served as a negative of the desired network. A polymer was poured in and, once set, microcapillaries 0.3 millimeters in diameter were filled with plasma, metal or a dielectric gas. Using this replica-molding technique they perfected the dimensions and spacings of the microcapillaries in the lattice. They showed that rapid changes in the electromagnetic characteristics of […]

Structured light promises path to faster, more secure communications

Eurekalert  November 5, 2019 Researchers in South Africa review the progress being made in using structured light in quantum protocols to create a larger encoding alphabet, stronger security and better resistance to noise. Since patterns of light can be distinguished from each other, they can be used as a form of alphabet. Its information capacity is much higher than polarized light and security is stronger, and the robustness to noise is improved. It turns out that many protocols can be efficiently implemented withotterns of light. Unfortunately, the toolkit to manage these patterns is still underdeveloped and requires a lot of […]