摘要:

AbstractA comparative analysis between frequency scanning and multispot satellite systems has been performed in the context of land mobile applications. The aim of the work has been to confirm the effectiveness of the frequency scanning approach, whose technical feasibility has already been proved by the authors in a previous study, also in a comparative investigation with a more conventional satellite configuration.A proper comparative methodology has been established to compare two baseline configurations of the two systems. The analysis has also been rendered parametric, varying some system characteristics such as bandwidth, traffic distributions and linearity requirement. The achieved results are provided and widely commented on in the paper.

ISSN:0737-2884    

DOI:10.1002/sat.4600130202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractThe design of line of sight (L.O.S.) or satellite links requires annual point rainfall rate statistics for several percentages of time in the locations where the radiocommunication links are planned. Rain rate data within an average year, indeed, allow the estimation of the time percentage during which attenuation due to rain is significant, and consequently the future link margin.To meet ITU Radiocommunication Sector's Recommendations, we propose a probability law model allowing the prediction of the rainfall rate cumulative distribution in temperate and tropical climates.This model, which can be easily used, may serve as a very useful and accurate enough tool for radiocommunication engineers and scientists.

ISSN:0737-2884    

DOI:10.1002/sat.4600130203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractThis paper deals with satellite payload architectures adequate for the provision of universal mobile telecommunication services (UMTS) by medium altitude earth and geostationary orbit (MEO and GEO) satellites. The payload concept introduced is based on a transparent transponder with onboard digital signal processing (DSP) operations and digital beamforming at the traffic carrier level (narrowband beamforming). The emphasis of the paper is on key design aspects and technology considerations of the payload processor unit (PPU), which includes multiplexing/demultiplexing and digital beamforming operations, and on the antenna and RF signal handling subsystems. For completeness, a review on the European digital technology is also presented. The development of such a payload architecture is in line with present and planned activities of the European Space Agency (ESA) for MEO and GEO orbit systems, which are also implicitly discussed in the paper.

ISSN:0737-2884    

DOI:10.1002/sat.4600130204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractIt is known that concatenated coding can significantly enhance the performance of digital communication systems operating over fading channels when compared to uncoded or single‐coded systems. The price to be paid for such an improvement, however, is a substantial increase in the required bandwidth. In this paper, we consider the use of a concatenation scheme in which the inner code is a trellis‐coded modulation (TCM) system. The analysis is carried out for two different outer codes: a binary Golay code and a non‐binary Reed‐Solomon code. Results obtained for the Rayleigh and Rician fading channels through analytical bounds indicate that the use of this system does provide a significant reduction in the bit error probability, a fact that is also verified through computer simulation. Unlike a traditional concatenated system, the proposed method achieves the coding gain while maintaining acceptable bandwidth eff

ISSN:0737-2884    

DOI:10.1002/sat.4600130205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

ISSN:0737-2884    

DOI:10.1002/sat.4600130201

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY