M. Lucente

Perspectives of W-Band for Space Communications

In this paper, the main trends of the latest space missions will be outlined, dealing with the advantages of using W-band in space communication systems. In the first part, an overview of the current projects involved in the study of W-band is shown, highlighting the reasons of its future widespread.

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.

Design of Flower Constellations for Telecommunication Services

Satellite constellation designers take into consideration the entire telecommunication network and their design choices are influenced by many factors including: number of satellites, orbital characteristics, coverage area, network interconnections, system cost, and complexity. When the satellite constellation design method does not include a large number of possible configurations, then the final result of the design process is a suboptimal solution. Flower Constellation (FC) design provides a relatively new design approach which can overcome this problem. The time evolution of the FC theory is here summarized and the fundamental mathematics allowing the constellation design is provided. In particular, the theory is applied to the design and optimization of constellations maximizing the global coverage and the network connectivity via intersatellite links. Performance results are compared to the classical type of satellite constellations, i.e., the Walker Constellations. The performance improvement provided by FC design with respect to Walker Constellation design is shown. Finally, considerations regarding the cost for deployment and orbital control are also provided.

The WAVE mission payload

In this paper, an overview of the WAVE mission payload architecture is presented. WAVE (W-band Analysis and VErification) is the new project funded by the Italian Space Agency (ASI). The aim is to design and develop a W-band geostationary (GEO) payload to be deployed for scientific experimental studies of the W-band channel and possible utilization in satellite data communications. The large bandwidth availability in the W-band range allows conceiving and proposing advanced services for future scenarios in order to meet high-quality requirements for a large number of users. The major parameters of the payload architecture are discussed in addition to the different requirements and specifications of the on-board transmission and reception components and their dependence on the host platform

IKNOW Mission: Payload Design for In Orbit Test of W Band Technology

This paper presents the payload design for an in orbit test of W band technology called IKNOW mission (In orbit Key-test and validatioN Of W band). The increasing demand for frequency bands with large bandwidth availability to satisfy satellite communications applications requirements renders mandatory the need to explore higher and higher frequency ranges. W band (75-110 GHz) could represent the answer to these needs due to the large bandwidth availability, allowing to propose many innovative services that need high-volume transfers. Therefore, the exploitation of W band is foreseen in order to meet the high-quality data transmission for a large number of end users and data-oriented services. The IKNOW mission is a demonstrative experiment foreseen within the phase A2 of the WAVE (W band analysis and verification) project, a study funded by the Italian Space Agency (ASI), which aims at designing and developing W band payloads for telecommunication applications. This paper will be focused on the characterization of the IKNOW mission within the WAVE project devoted to carry out a preliminary channel propagation assessment. Specifically, special attention will be paid to the payload design, particularly critical from the technological point of view at these high frequencies. The basic idea is to develop the receiving/transmitting chain using MMIC devices, in order to fit cost, power and weight constraints, typically limited for a spacecraft. Technological critical items will be highlighted, focusing on the present state of the art and presenting some architectural choices. Moreover, some simulations based on ADS software will be reported in order to simulate the performance of the identified payload configuration.

IR-UWB for high bit rate communications beyond 60 GHz

The recently allocated 71–76 GHz and 81–86 GHz bands provide an opportunity for Line Of Sight (LOS) links for directional point-to-point “last mile” links. An efficient use of this spectrum may allow wireless to finally “catch up” with wires, leading to systems such as “multi-Gigabit wireless Ethernet,” and “wireless fiber.” However, the transmission at such a frequency range is characterized by several additional challenges compared to lower frequency bands, from the technological and propagation point of view, which makes difficult to use them efficiently. In this scenario, IR-UWB technology might offer some more degrees of freedom for the design of a highly integrated, low cost transceiver. This work has at its core the design and BER (Bit Error Rate) performance evaluation of an IR-UWB architecture based on an 85 GHz (this frequency belongs to W band/75–110 GHz) up-conversion stage of train of Gaussian pulses having a duration lower than 1 ns. Finally, we compare performance of this architecture with the ones of a more traditional continuous wave communications system with FSK (Frequency Shift Keying) modulation. Simulation results show that BER performance, in presence of RF non-linearities, for an IR-UWB transceiver architecture operating at W band (with same data rate and bandwidth) are better than a coherent BFSK scheme working in a similar scenario.

IKNOW: a Small LEO Satellite for W Band Experimentation

An interesting future alternative to intensively-exploited Ku and Ka bands for high-data rate transmission over satellite networks is represented by the higher frequency ranges such as W band (75-110 GHz). In this context, some experiments targeted to verify the feasibility of W band exploitation for telecommunication services deployment are being carried out. The IKNOW (In-orbit Key-test and validatioN Of W band) mission is an advanced feasibility study within the framework of WAVE (W band Analysis and VErification) project, an Italian Space Agency (ASI) study aimed at designing and developing a W band telecommunication payload. In this paper, authors will focus their attention on the IKNOW satellite mission, introducing both mission and payload architectures, in addition to some receiving chain simulations.

Flower Constellations for Telemedicine Services

Flower constellations are a particular set of satellite constellations where every satellite covers the same repeating space track. When the flower constellations are visualized on an Earth centred earth fixed reference frame, the relative orbits shows flower-shaped figures centered on the Earth. In this paper the shape and the position of a particular flower constellations has been designed for the provision of telemedicine services. Once that performance metrics of the constellation have been defined and the service targets have been identified, the performance of the flower constellation have been compared with the well known polar and Walker constellations. The particular properties of the flower constellations allow an optimized coverage of a list of targets. It was found that the flower constellations provide better performance in terms access availability and mean access time.

New developments in the WAVE W-band mission

In this paper, an overview of the evolution towards the second phase (A2) of the WAVE (W-band analysis and verification) project is made, and the timeline for the development of a future pre-operative space mission is defined. This includes the definition of a number of advanced preliminary W-band applications such as the utilization of the M-55 Geophysica manned stratospheric aircraft for a number of experiments on the channel propagation in W-band 94 GHz and 82 GHz; the introduction of the LEO nano-satellite mission IKNOW (in-orbit key-test and validation of W-band) which is used for a first uplink-downlink satellite channel characterization and in-orbit validation of W-band technology and space qualification processes. These applications are expected to provide the necessary elements towards the realization of the GEO pre-operative payload defined in the phase-A of the project

TRANSPONDERS: Research and analysis for the development of telecommunication payloads in Q/v bands

Since the 70s Italy has had a pioneering approach to higher frequencies, at first at Ka band (20/30 GHz) with the Sirio experience (launched in 1978), when such a range was still a frontier, and then with Italsat F1 and F2 experiments in the 90s [1], studying Q and V bands in addition to Ka one as well. After those experiences, Italy through the Italian Space Agency (ASI) was one of the first European countries that have made an effort toward the exploitation of Q/V band in telecommunications. In 2004 ASI funded a feasibility study (phase A), called TRANSPONDERS, Italian acronym for “research, analysis and study of Q/V payloads for telecommunications”, aimed at studying and designing a payload to be used to fully characterize the channel at Q/V bands and to test novel adaptive interference/fading mitigation techniques such as ACM (Adaptive Coding and Modulation). Finally, the feasibility and performance of preliminary broadband services in such frequencies can be verified through this study .A new phase has recently started (April 2008), called TRANSPONDERS-2 and leaded by Space Engineering S.p.A., to continue the achievements gained during the first phase. In this scenario, it is mandatory to identify pre-operative experimental missions aiming at fully verifying the feasibility of future Q/V bands satellite telecommunication applications. The experimental goals are mainly to test the effectiveness of Propagation Impairment Mitigation Techniques (PIMTs) [2] in such frequency bands and the minimization of implementation risks for operative system characterized by a series of technological challenges.