In order to allow new frequency ranges for broadband satellite communication and to ensure the steadily growing demand for higher data rates, we propose the world's first in-orbit verification of a communication link in the E-band  with the project EIVE.
A data downlink in the frequency range 71-76 GHz from a nanosatellite to a ground station is planned. Detailed link budget calculations show the feasibility of a transmission in a polar low-earth orbit with a very large bandwidth of 5 GHz while using realistic compact antenna dimensions.
State-of-the art compound semiconductor technologies were used to design e.g. GaN solid-state power amplifiers (SSPA) and GaAs low-noise preamplifiers (LNA) developed by project partners in previous DLR projects. Using this existing hardware, record terrestrial other-the-air data transmission in the E-band of up to 6 Gbps over 37 km distance was already achieved and a 9.6 Gbps transmission was demonstrated using an aircraft at a distance of up to 12 km from a ground station with antenna tracking.
The partners of the EIVE project group are highly qualified for the implementation of this project due to their extensive know-how in their respective field which perfectly fits to the required competencies necessary to successfully carry out the EIVE project. In the DLR projects GISALI, ACCESS and ELIPSE coordinated by the group led by Prof. Kallfass, the Fraunhofer IAF, the Karlsruhe Institute of Technology, the Radiometer Physics GmbH and the University of Stuttgart developed the existing E-band technology platform and demonstrated the worldwide first data transmission between an aircraft and a ground station. The group led by Prof. Klinkner at the University of Stuttgart developed and operates the small satellite "Flying Laptop". The Tesat Spacecom is another industry partner with extensive expertise in space technologies and applications.
On the one hand, with the planned data downlink from a Cubesat platform to the ground station, the feasibility of high speed data links in a new frequency range for satellite communications will be assessed in an in-orbit scenario. On the other hand, applications and services for earth observation will be addressed with the planned payload, since in the future, such applications could increasingly be served by nanosatellites in the low-earth-orbit (LEO). For various applications based on W-band satellite communications such as e.g. Inter-satellite links (ISL) or duplex-capable data links for global mobile and Internet coverage via satellite networks (5G, 6G, etc.), innovative platforms such as small satellites with correspondingly more complex payloads and innovative antenna technologies will be highly attractive in the future.
 The ITU regulated frequency bands at 71-76 GHz (downlink) and 81-86 GHz (uplink) are in the so-called E-band (WR12, corresponding to the 60-90 GHz frequency range). The ESA has used the term W-band (WR10, corresponding to the 75-110 GHz frequency range) for these frequency ranges in recent ITTs.
- Demonstration of an RF link in the E-band at 71 - 76 GHz between a satellite and a ground station.
- The RF link shall achieve a RF bandwidth of 5 GHz with a useful bandwidth of 2.5 GHz.
- The influence of different weather phenomena (e.g. clouds, rain, snow, ...) on the RF link shall be characterised.
- Pseudo-random data created by an arbitrary waveform generator shall be looped continuously at a sample rate of 2.5 GSps. Different modulation schemes may be used during the transmission of pseudo-random data.
- Uncompressed video data from a high-resolution camera shall be transmitted via the E-band transmitter live and in real time. This should demonstrate that aside from known data, real data can be transmitted at a high bandwidth.
- Video data should be able to be stored on-board of the EIVE satellite in a compressed format.
- Arbitrary data stored on-board the CubeSat shall be transmitted via the E-band transmitter using different modulation schemes.
- The video camera should be used for Earth observation purposes.
|2019||Start of project|
|2020||Integration / test campaign|
The E-band payload consists of two self-developed GaN Solid State Power amplifiers as well as a low-noise GaAs pre-amplifier. A block diagram of the E-band transmitter is shown above this text. A horn antenna with a high gain is used in order to achieve a positive link budget. The utilised radiofrequency components are mounted on the body of the horn antenna which serves as a capacitive heat sink for the dissipated energy during the ground station passes.
The need for a high-bandwidth data source drove the decision to implement a high-resolution video camera to utilise the entire bandwidth of the link. The camera can be further used for Earth observation purposes as well.
The satellite bus serves as the carrier of the payload and enables its operation with respect to the requirements and constraints of the mission.
A 6U structure (100 mm x 220 mm x 340 mm) was chosen as the base of the EIVE CubeSat.
Electric Power Supply
Two deployable solar panels supported by two body-mounted solar panels with 14 solar cells each supply the power needed for the operation of the EIVE CubeSat. A lithium ion battery will maintain the system during the eclipse phases. A power control and conditioning unit regultates the solar power and supplies each subsystem with the appropriate voltages while also implementing the necessary safety features. Most subsystems can be independently switched on and off.
Attitude Control System
The EIVE CubeSat employs a variety of attitude sensors and actuators. Angular rates and the magnetic field strength are measured by a combination of different MEMS sensors. Additionally, segmented photo diodes enable the determination of the sun vector in relation to the body frame. In order to comply with the demand for a high-precision attitude accuracy during the payload operation, a star tracker will be used. Thus, the pointing knowledge can be pushed well below one degree. Magnetorquers enable a coarse attitude control, whereas reaction wheels will be used to increase the agility and the pointing accuracy during the payload operation.
The on-board computer of the EIVE CubeSat is build around a Xilinx Zynq 7020 System-on-a-Chip comprising an ARM microprocessor as well as an FPGA. The flight software is based on the successful flight software framework of the Flying Laptop satellite.
The EIVE CubeSat will use an S-Band transceiver with a downlink frequency of 2263.5 MHz for telemetry and data as well as an uplink frequency of 2083.5 MHz for tele-commands. Two low-gain patch antennas mounted on opposing sided of the CubeSat structure will offer an almost omni-directional coverage. The RF link will use the well-established CCSDS protocol.
Thermal Control System
The thermal control system bundles temperature measurements of board mounted sensors as well as 16 resistance temperature devices. Six film heaters can be used to increase the temperature of critical subsystems if needed. The satellite will be cooled entirely passive.
The main ground station of the EIVE mission will be located at the campus of the University of Stuttgart in Vaihingen. Additional ground stations of the IRS partners around the globe are available for the reception of telemetry and payload data as well as in exceptions the transmission of tele-commands both in the S-band frequency range. The reception of E-band signals will be solely conducted via the IRS ground station in Vaihingen.
The E-band signals are received with a parabolic antenna with an integrated LNO, an AGC circuit, a broadband downconverter and a base-band amplifier. The digitalisation and processing of the received signals is done in the consecutive steps. A block diagram of the signal path is displayed above this text.
Tele-commands and telemetry are received and send using the already existing parabolic antenna with an integrated CORTEX receiver located at the IRS. The operation of the S-band ground station will be modified in the near future to comply with the demands for multi-mission / multi-ground station capabilities.
Institute of Robust Power Semiconductor Systems
The Institute of Robust Power Semiconductor Systems of the University of Stuttgart manages the EIVE project.
Main tasks of the space segment are the design, integration and operation of the basis band payload. Concerning the ground segment, the ILH supervises the operation of the payload and the scientific analysis of the gathered data.
Institute of Space Systems
The Institute of Space Systems of the University of Stuttgart is responsible for the design, construction and integration of the satellite bus. Further, the IRS manages the satellite operation utilising the IRS ground station as well as external ground stations.
Fraunhofer-Institute for Applied Solid State Physics
The Fraunhofer-Institute for Applied Solid State Physics works on the E-band payload by developing the GaN-Solid-State-Power-Amplifier (SSPA) as well as the low-noise mHEMT receiver amplifiers (LNA).
RPG-Radiometer Physics GmbH
The Radiometer Physics company develops the E-band horn antenna for the CubeSat as well as the E-band antenna and electronic components for the ground station's reception antenna. This includes the RF tracking of the E-band signal.
|2019-10-24||golem.de||Nanosatelliten bringen Gigabit bei 71 bis 86 GHz|
|2019-10-23||Informatikdienst Wissenschaft||Schnelles Internet: Jederzeit und über-ALL|
|2019-10-23||raumfahrer.net||EIVE: Erschließung neuer Frequenzbänder|
|2019-10-23||Clusterportal Baden-Württemberg||Deutsche Forscher arbeiten an der Erschließung neuer Frequenzbänder|
|2019-10-23||Hochschulkommunikation Uni Stuttgart||Schnelles Internet: Jederzeit und über-ALL|
Information for Students
The EIVE project continuously offers opportunities to conduct bachelor or master theses as well as to do student assistant positions. Open positions can be found on the ILH and IRS pages linked below. Student interested in these opportunities or further not published topics should contact the appropriate person at the ILH or IRS.