Wearable Metamaterial Dual-Polarized High Isolation UWB MIMO Vivaldi Antenna for 5G and Satellite Communications

A low-profile Multiple Input Multiple Output (MIMO) antenna showing dual polarization, low mutual coupling, and acceptable diversity gain is presented by this paper. The antenna introduces the requirements of fifth generation (5G) and the satellite communications. A horizontally (4.8–31 GHz) and vertically polarized (7.6–37 GHz) modified antipodal Vivaldi antennas are simulated, fabricated, and integrated, and then their characteristics are examined. An ultra-wideband (UWB) at working bandwidths of 3.7–3.85 GHz and 5–40 GHz are achieved. Low mutual coupling of less than −22 dB is achieved after loading the antenna with cross-curves, staircase meander line, and integration of the metamaterial elements. The antennas are designed on a denim textile substrate with = 1.4 and h= 0.5 mm. A conductive textile called ShieldIt is utilized as conductor with conductivity of 1.8 × 104. After optimizing the proposed UWB-MIMO antenna’s characteristics, it is increased to four elements positioned at the four corners of a denim textile substrate to be employed as a UWB-MIMO antenna for handset communications, 5G, Ka and Ku band, and satellite communications (X-band). The proposed eight port UWB-MIMO antenna has a maximum gain of 10.7 dBi, 98% radiation efficiency, less than 0.01 ECC, and acceptable diversity gain. Afterwards, the eight-ports antenna performance is examined on a simulated real voxel hand and chest. Then, it is evaluated and compared on physical hand and chest of body. Evidently, the simulated and measured results show good agreement between them. The proposed UWB-MIMO antenna offers a compact and flexible design, which is suitably wearable for 5G and satellite communications applications.

Supporting Decommissioning/Conversion of Offshore Structures Applying Innovative Technological Solution INSURE project

Companies that work in the decommissioning of platforms need tools to make smarter and informed business decisions, manage and analyse business data, increase the security of workers and operate under strict environmental protection regulations. INSURE aims at assessing the feasibility of a new service to support the decommissioning of offshore installations by means of technological innovation made available throughout each process’ step. In order to accomplish this, the project gathers high-impact Italian companies bringing together the best applicable technological and scientific know-how. INSURE foresees to combine these know-hows and create a novel tool at the service of the industry to promote a better and safer approach to the operations. Targets of the INSURE project are improving workers’ safety, enhancing environmental monitorings, increasing operations’ efficiency, reducing operational costs, offering a route for future sustainability. Project targets can be achieved through the realisation of an augmented virtual reality platform (AVRP) that will be operated in support of the decommissioning process where the data acquired/transmitted by a plurality of sensors will converge. A fleet control tool integrates information from sensors installed on autonomous aerial and underwater vehicles making use of the Global Satellite Navigation Systems (GSNS) and Satellite Communications (SatCom). The convergence of top-notch technologies (augmented/virtual reality, 3D, robotics, sensors, 5G and Satellite services), together with a cloud of infrastructure, enables a fast and complete access to real-time data at very high resolution. The proposal aims to bring the actual data and information access from the Internet of Things to the Internet of Knowledge paradigm. Confrontation with national and international possible end-users produced a set of user requirements guiding the design of a feasibility study for the realisation of one specific product. The study also includes the evaluation of economic, non-economic viability and possible regulatory constraints to its realisation. The INSURE feasibility study creates the intellectual background for the further step of the process: the realisation and development of a pilot project tailored for the purpose. This combined use of novel technologies represents an innovative integrated approach applied to the management of offshore structures undergoing decommissioning or reconfiguration for other purposes. In addition, it also involves the promotion of sustainable opportunities for commercial, social and educational exploitation of areas and assets (including, for example, the ambit of eco-tourism, renewable energies, carbon capture and storage).

Efficient Iterative Timing Recovery of Low-Density Parity-Check Decoding Metrics Using the Steepest Descent Algorithm for Satellite Communications at Low SNRs

An efficient iterative timing recovery via steepest descent of low-density parity-check (LDPC) decoding metrics is presented. In the proposed algorithm, a more accurate symbol timing synchronization is achieved at a low signal-to-noise (SNR) without any pilot symbol by maximizing the sum of the square of all soft metrics in LDPC decoding. The principle of the above-proposed algorithm is analyzed theoretically with the evolution trend of the probability mean of the soft LDPC decoding metrics by the Gaussian approximation. In addition, an efficiently approximate gradient descent algorithm is adopted to obtain excellent timing recovery with rather low complexity and global convergence. Finally, a complete timing recovery is accomplished where the proposed scheme performs fine timing capture, followed by a traditional Mueller–Müller (M&M) timing recovery, which acquires timing track. Using the proposed iterative timing recovery method, the simulation results indicate that the performance of the LDPC coded binary phase shift keying (BPSK) scheme with rather large timing errors is just within 0.1 dB of the ideal code performance at the cost of some rational computation and storage. Therefore, the proposed iterative timing recovery can be efficiently applied on occasions of the weak signal timing synchronization in satellite communications and so on.

ISRO’s Geostationary data products archival & dissemination – Retrospect and prospect

Natural extreme weather events have been causing excessive damage to life and property across the globe since time immemorial. Space based techniques and instruments have been improvised and utilised over the years to generate and collect earth observations data. Although a significant amount of research has led to meaningful forecasts of extreme weather events leading to minimising of the loss of life and property, the analytical approaches in this field need to be further studied and explored. Also, since every instance of earth observation is significant in multiple time domains (current as well as past which is required for climatology studies), it needs to be archived and disseminated in an organised and holistic manner. For long time preservation, modern infrastructure and underlying cutting edge technologies need to be adapted. With missions like GISAT, where the volume of data handled per day will be around 200 Mega bytes per second, multi level strategic approach for archival and high speed bandwidth for near real time data dissemination on public networks should be complemented with data broadcast to strategic users, using satellite communications. This paper describes the current infrastructure established for archival and dissemination and archival of ISRO’s Met-Ocean data observations and the future road map in the area of instantaneous data and weather alerts dissemination through an Indian broadcasting system (IMETCAST). This is to ensure timely delivery of satellite data to end users to facilitate near real time analysis of weather events.

Investigation of accuracy of rain-rate and rain-attenuation prediction models in satellite communications based on meteorological skills

Rainfall is a major destructive factor which severely reduces the quality and reliability of propagated signals in satellite communications. Hence, rain-attenuation prediction plays a vital role in the satellite radio link planning and engineering. The accuracy of the rain-attenuation prediction models depends on two things; (i) the accuracy of rain-rate information and (ii) the area of study. Therefore, selecting an appropriate rain-attenuation prediction model for a new site without having any specific prediction model and experimental measured rain-rate would be challenging. In this regard, this letter takes advantage of climatology skills to find an accurate model for such kind of areas. To do so, we study the Urmia-site (37.55° N, 45.1° E) and its communication link with the Eutelsat 25A (25.5° E), where there is no available experimental measured data and specific prediction models for that site. Therefore, based on the meteorological skills, the Yong-in site in South-Korea (37.43° N, 126.93° E) was chosen, as a homogeneous area with Urmia, which has available measured data of rainfall and rain-attenuation. Afterward, the most common used global prediction models are applied to Yong-in and the results are compared with the existing measurements. Consequently, the more accurate rain-rate and rain-attenuation prediction models are investigated and generalized to Urmia, which are the ITU-R P.837-5 model with 34% r.m.s. and the Joo-Hwan model with 18% r.m.s., respectively. Finally, the amount of rain-attenuation in different useful frequency bands (10-50 GHz) is investigated for Urmia by the Joo-Hwan model.

The CODYSUN Approach: A Novel Distributed Paradigm for Dynamic Spectrum Sharing in Satellite Communications

With a constant increase in the number of deployed satellites, it is expected that the current fixed spectrum allocation in satellite communications (SATCOM) will migrate towards more dynamic and flexible spectrum sharing rules. This migration is accelerated due to the introduction of new terrestrial services in bands used by satellite services. Therefore, it is important to design dynamic spectrum sharing (DSS) solutions that can maximize spectrum utilization and support coexistence between a high number of satellite and terrestrial networks operating in the same spectrum bands. Several DSS solutions for SATCOM exist, however, they are mainly centralized solutions and might lead to scalability issues with increasing satellite density. This paper describes two distributed DSS techniques for efficient spectrum sharing across multiple satellite systems (geostationary and non-geostationary satellites with earth stations in motion) and terrestrial networks, with a focus on increasing spectrum utilization and minimizing the impact of interference between satellite and terrestrial segments. Two relevant SATCOM use cases have been selected for dynamic spectrum sharing: the opportunistic sharing of satellite and terrestrial systems in (i) downlink Ka-band and (ii) uplink Ka-band. For the two selected use cases, the performance of proposed DSS techniques has been analyzed and compared to static spectrum allocation. Notable performance gains have been obtained.