Piero Angeletti

Co-channel signal power measurement methodology in a communication and payload joint simulator

In this paper we provide payload designers with a new methodology to accurately assess the impact of the payload sub-systems onto the end-to-end system performance. The final goal is to have a reliable tool able to model any payload architecture, including the antenna section and a realistic signal excitation to eventually estimate the signal distortions and deviation from ideal performance induced by non ideal response of the payload elements. I. Introduction O far most of the telecommunication satellite payloads have been designed without taking into account the physical layer system performance and therefore showing a conservative approach based on legacy engineering experience. The impact of payload sub-systems non-ideal behavior is often difficult to be assessed from an end-toend system point of view. Hence payload specifications are often based on a performance requirement breakdown referring to every individual sub-system level and not always clearly related to the overall system design perspective. As an example in advanced payload architectures using distributed amplification (such as multi port amplifiers or active and semi-active antennas) different signals are jointly interacting in a complex non-linear environment and the impact of possible transmit chain phase and amplitude tracking errors in the presence of nonlinear multi-carrier HPA operations are very difficult to estimate both at sub-system and end-to-end level. A very detailed payload and modulator/demodulator simulator can be realized but certainly it is not manageable by payload designers other than becoming more and more complex due to the latest innovations on physical layer techniques (e.g. near-Shannon coding, higher order modulations with pre-distortion techniques, adaptive coding and modulation etc..) and complex payload architectures. S

Performance Assessment of Output Sections of Satellite Flexible Payloads

In communication satellite systems, the payload utilization can be improved by means of the reconfigurability of the RF power among different beams and channels as an alternative to the well-known multiple antenna beams. The performance of a reconfigurable payload strictly depends on the architecture of its high-power section. In particular, the use of Multiport Amplifiers (MPAs) is generally considered the most effective means of achieving a high level of on-board RF power flexibility. This paper trades-off two multi-amplifier architectures based on both standard traveling-wave Tubes (TWTAs) and MPAs, with the objective of assessing the provided on-board power flexibility and overall DC-RF power efficiency. In addition, the two solutions will be evaluated according to their capability of achieving the required quality in end-to-end satellite link with a minimum DC power consumption, still guaranteeing some realistic margins on the link budget. The comparisons are performed by means of an in-house ESA developed software simulator able to analyze the impact of any payload non-ideality on the end-to-end link performance; in particular, the reference signal impairments are estimated by the carrier-to-interference ratio, evaluated with the correlation method.

Accurate characterization of TWTA distortion in multicarrier operation by means of a correlation-based method

Complex payload architectures, together with the use of high-order digital modulations and advanced coding schemes, call for a new interpretation of the traveling-wave tube (TWT) linearity parameters. We propose a correlation-based methodology to assess in a simple, yet effective, manner the level of intermodulation (IM) generated by the TWT nonlinearity; this method is particularly suited to accurate IM evaluation in the presence of multicarrier operation with non-constant envelope modulations.

Multi-Amplifiers Architectures for Power Reconfigurability

In communication satellite systems, the reconfigurability of the RF power among different beams and channels can be employed in alternative to the well-known multiple antenna beams, in order to improve the payload utilization. The performance of a reconfigurable payload strictly depends on the architecture of the high-power section. Two multi- amplifiers architectures, one based on bias-adjustable Traveling-wave Tubes (flex-TWTAs), the other based on Multiport Amplifiers, will be traded-off against the achievable efficiency and degree of flexibility at payload level.

Performance analysis of satellite payload output sections based on Multiport Amplifiers

The performance of a reconfigurable telecommunication satellite payload strictly depends on the architecture of its high-power section. This paper trades-off two multi-amplifier architectures based on both standard traveling-wave Tubes (TWTAs) and MPAs (Multiport Amplifiers), with the objective of assessing the provided on-board power flexibility, the overall DC-RF power efficiency and power consumption.

Flexible payload architecture for multiple shaped-beam coverage from a S-DMB geostationary satellite system

The paper presents the proposed architecture and the optimization results of a flexible payload for S-band mobile broadcasting to multiple shaped-beams. A key element in the payload is constituted by the high power section which provides RF power generation and distribution to feeds with appropriate amplitude and/or phase beamforming constraints to realize different shaped coverages. The outcome of the design and optimization activity is a promising architectural solution showing a high degree of coverage reconfigurability as well as an almost full freedom in power-to-beam allocation.

A discrete aperiodic active lens for multibeam satellite applications

In the paper one aperiodic constrained active lens generating a multiple spot contiguous beams coverage is proposed. The antenna is optimized in terms of number of radiators, dimensions, weight, and power amplifiers efficiency. The antenna represents an interesting architecture based on a single aperture able to replace conventional antennas based on multi reflector dishes onboard geo or non-geo stationary satellites. Experimental results recently achieved are presented.

Generalized Thru-Reflect-Line Calibration Technique for the Measurement of Multimodal Radiating Waveguides

The objective of this letter is to extend the use of the generalized thru-reflect-line measurement technique to the case of a radiating multimodal rectangular waveguide aperture. Although this radiating aperture has been carefully studied from a theoretical point of view, the relevant experimental characterization has been limited to the case where the feeding waveguide is monomodal. In addition to theory, we also present experimental results that agree quite well with full-wave simulations, thereby fully validating the measurement technique.

On Ground Beam Forming and Multi User Detection Proof of Concept

In the frame of the on-going ARTES-5.1 ESA project “On Ground Beam Forming Networks And Multi User Detection Proof Of Concept” different scenarios of interest for the OGBF with Multi user detection technique has been defined, based on a single S-Band GEO satellite. This paper is focused on the definition and design of a hardware test bed implementing a scaled version of an OGBF/MUD system in order to verify the achievable performance. The OGBF demonstrator test bed includes a traffic emulator with relevant channel impairments, a satellite emulator including frequency conversion and multiplexing of the feeds signals and HPA emulation, and a gateway emulator with on ground frequency conversion, digital demultiplexing and MMSE-SIC based Multi user detector.

On-Ground Beamforming and Interference Cancellation for next generation mobile systems

On-Ground-Beam-Forming (OGBF) is a well-known technique which was however relatively ignored in the satellite communication field until recently when it has been adopted in some mobile system in place of on-board Beam Forming for its higher flexibility and lower payload complexity. OFBF also paves the road to higher capacity interactive systems thanks to the possibility of dynamic beamforming optimized to the set of users being served in each given time interval. The present paper will present some trade-offs concerning OGBF, including on-board payload complexity, calibration issues and feasibility of dynamic OGBF in a mobile environment.