Ernestina Cianca

EHF for Satellite Communications: The New Broadband Frontier

The exploitation of extremely high-frequency (EHF) bands (30-300 GHz) for broadband transmission over satellite links is currently a hot research topic. In particular, the Q-V band (30-50 GHz) and W-band (75-110 GHz) seem to offer very promising perspectives. This paper aims at presenting an overview of the current status of research and technology in EHF satellite communications and taking a look at future perspectives in terms of applications and services. Challenges and open issues are adequately considered together with some viable solutions and future developments. The proposed analysis highlighted the need for a reliable propagation model based on experimental data acquired in orbit. Other critical aspects should be faced at the PHY-layer level in order to manage the tradeoff between power efficiency, spectral efficiency, and robustness against link distortions. As far as networking aspects are concerned, the large bandwidth availability should be converted into increased throughput by means of suitable radio resource management and transport protocols, able to support very high data rates in long-range aerospace scenarios.

Integrated satellite-HAP systems

Thus far, high-altitude platform (HAP)-based systems have been mainly conceived as an alternative to satellites for complementing the terrestrial network. This article aims to show that HAP should no longer be seen as a competitor technology by investors of satellites, but as a key element for an efficient hybrid terrestrial-satellite communication system. Two integrated HAP-satellite scenarios are presented, in which the HAP is used to overcome some of the shortcomings of satellite-based communications. Moreover, it is shown that the integration of HAPs with satellite systems can be used to provide more efficient fleet-management and traffic-control services and more powerful data-relay systems.

Satellite Communications Supporting Internet of Remote Things

This paper focuses on the use of satellite communication systems for the support of Internet of Things (IoT). We refer to the IoT paradigm as the means to collect data from sensors or RFID and to send control messages to actuators. In many application scenarios, sensors and actuators are distributed over a very wide area; in some cases, they are located in remote areas where they are not served by terrestrial access networks and, as a consequence, the use of satellite communication systems becomes of paramount importance for the Internet of Remote Things (IoRT). The enabling factors of IoRT through satellite are: 1) the interoperability between satellite systems and sensors/actuators and 2) the support of IPv6 over satellite. Furthermore, radio resource management algorithms are required to enhance the efficiency of IoT over satellite. In this work, we provide an integrated view of satellite-based IoT, handling this topic as a jigsaw puzzle where the pieces to be assembled are represented by the following topics: MAC protocols for satellite routed sensor networks, efficient IPv6 support, heterogeneous networks interoperability, quality of service (QoS) management, and group-based communications.

SALICE project: Satellite-Assisted Localization and Communication Systems for Emergency Services

Restoring the connectivity in the emergency areas and providing NAV/COM services able to support and coordinate the rescue teams represent two of the main telecommunication needs for efficient emergency situation management. The SALICE (Satellite-Assisted LocalIzation and Communication system for Emergency services) Project aimed at identifying the system architecture and the most suitable solutions to be adopted in the future integrated reconfigurable NAV/COM systems and to analyze their feasibility in realistic emergency scenarios. The article analyzes the proposed strategies and the most significant project results in pursuing both the global coverage of the emergency areas and the development of a reconfigurable and cooperative NAV/COM system.

Energy Efficient Wireless Networks Towards Green Communications

Wireless networks have become an essential part of the modern life. However, currently, 3% of the world-wide energy is consumed by the ICT infrastructures which causes about 2% of the world-wide CO2 emissions. The transmitted data-volume increases rapidly and wireless communications are used extensively while network design rules have practically ignored the energy efficient network design approach to limit CO2 emissions. This approach is currently named Green Communications. Significant energy savings in mobile networks can be expected by defining and standardizing energy efficiency metrics and combining energy aware flexible radios and networks. This paper discusses several techniques such as cross layer approach, multiple antennas, cell size reduction and cognitive radio, from the system-wide energy efficiency point of view, outlining challenges and open issues.

Stratospheric relay: potentialities of new satellite-high altitude platforms integrated scenarios

In the frame of the development of future telecommunications systems, an integration of heterogeneous networks (wireline, wireless, terrestrial or space-based) is envisaged. High Altitude Platfonns (HAP) could play a key role, acting as “building blocks” of such systems; therefore, a new research area concerns their integration in satellite scenarios. This paper presents and analyses two conceivable HAPsatellite integrated scenarios, considering both radio and optical communications for the HAP-satellite links.

Channel-adaptive techniques in wireless communications: an overview

The concept of adaptivity is of paramount importance in the design of future communication systems, in which a careful exploitation of the limited available resources (bandwidth, power, etc.) is required. The potential of channel-adaptive transmission has been already recognized 30 years ago, but it did not receive much interest at that time. In the last decade, the advent of feasible software radio systems, and hence, the availability of fast flexible and reconfigurable transceivers has renewed interest in adaptive techniques, which include adaptive modulation and coding, adaptive antennas and adaptive equalization techniques. This paper focuses on adaptive modulation and adaptive error control mechanisms. Basic concepts are highlighted and an overview on the achieved results and new trends in this research area are presented. Some results from information theory are also presented, which show the limitations of these techniques and motivate further research on the practical and design issues that have to be addressed to enable performance to reach close to the theoretical limit. Copyright

Hybrid System HAP-WiFi for Incident Area Network

Recent large scale disasters have highlighted the importance of a robust and efficient public safety communication network able to coordinate emergency operations even when existing infrastructures are damaged. The Incident Area Network (IAN) is a self-forming temporary network infrastructures brought to the scene of an incident to support personal and local communications among different public safety end-users. In this work we are interested in investigating how the High Altitude Platform (HAP) can effectively support Multimedia Broadcast/Multicast Service (MBMS) in a scenario wherein the preexistent terrestrial network is not available. To this aim, we propose an efficient policy of Radio Resource Management (RRM) based on cooperation framework between HAP and Mobile Ad-Hoc NETwork (MANET). The proposed solution has been successfully tested through a comprehensive simulation campaign.

Experimental Italian Q/V band satellite network

Broadband technologies are taking a predominant role in the emerging information society. In particular, broadband satellite communication systems, with their global access and broadcasting capabilities, are well suited to answer to the requirements of the information society. This paper focuses on the efforts that are currently spent toward the development of EHF (Extremely High Frequency) satellite communications systems. In particular, Q/V (35–75 GHz) and W (75–110 GHz) bands, represent an almost “free” spectrum resource that could be used to realize the so-called satellite gigabit-connectivity, in order to support innovative broadband applications. This paper presents the most important features of an experimental Q/V band satellite network based on the Alphasat TDP#5 (Technology Demonstration Payload), an ongoing project, funded by the Italian Space Agency, that aims at carrying out communication and propagation experiments over a Q/V band satellite link.

Waveform design solutions for EHF broadband satellite communications

The problematic RF environment experienced by broadband satellite communications at EHF frequency bands, in particular Q/W bands, call for the use of novel waveforms. This paper presents a detailed comparison of several waveforms in presence of nonlinear distortions and typical values of phase noise introduced at Q/W band. Two main types of waveforms have been compared: Constant Envelope multicarrier waveforms (CE-OFDM and CE-SCFDMA) and single carrier impulse-based waveforms (TH-UWB, DS-UWB and PSWF-based PSM). This comparison will allow to draw some practical guidelines for the waveforms design of EHF broadband satellite communications.