摘要:

AbstractThis paper underlines the characteristics of a proposed mesh network for messaging applications in C‐band using spread ALOHA protocol. A simulation program has been developed for studying the behaviour of large networks employing ALOHA access or its variants. It is a simulation for a large population network consisting of thin traffic small messaging terminals (SMTs), and models an infinite user population which employs fixed length data packets. The program is general and allows for the study of either the mesh or the star connected networks. Certain variations of the classical ALOHA schemes, such as slotted ALOHA (with user selectable slot length) and spread ALOHA, have been studied for network operation. In the case of spread ALOHA access, the program can be run with Barker, pseudorandom, Ping Fai Li or any other spreading sequence. The results of the simulation have confirmed the utility of spread ALOHA as an access protocol for MESCOMNET. It has identified an operating point on the throughput‐traffic curve at which spread advantage is available for power reduction of S

ISSN:0737-2884    

DOI:10.1002/sat.4600100302

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

年代:1992

数据来源: WILEY

摘要:

AbstractThe forthcoming third generation of satellites incorporating multichannel demodulator (MCD) processors, and the needs apparent within aviation systems, induce the requirement for efficient band processing algorithms with specific regard to the quadrature processing arrangement.This paper presents a coherentz‐domain formulation of the pertinent digital transmultiplexer algorithms for the on‐board processing (OBP) scenario, with a view to establishing a set of desirable algorithmic properties suitable for the preferred complex oriented quadrature processing algorithms. Stemming from the principles set forth, an ensemble of new algorithms based upon mixes of Hilbert transforming and real transform algorithms is presented, wherein the established concepts relating to the telephone network transmultiplexer algorithms are able to be exploited in certain cases. Further, the computational load of one of the methods is lower than that of a known prominent OBP related technique. The computational necessities of the various algorithms are laid down for comparative purposes in addition to the mathematical descripti

ISSN:0737-2884    

DOI:10.1002/sat.4600100303

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

年代:1992

数据来源: WILEY

摘要:

AbstractThere are certain data services that could use transmit‐only land‐mobile satellite communication terminals. Such terminals would not be able to receive acknowledged messages and transmit themonward. Thus it is of interest to study alternative means of improving the system reliability. In this paper we propose the use of transmission to two satellites separated in azimuth and elevation in order to improve the reliability of throughput.We have investigated the improvements by building upon the model proposed by Lutz for land mobile satellite communications via one satellite, and extended this using measurements of the shadowing coefficient in different areas (suburban, countryside and city) to two separated satellites. The measured data is used to produce an empirical model of the equivalent shadowing coefficient variations with the separation angle variation between two satellites.The results show good agreement with the shadowing coefficients produced by the Lutz model for a single satellite. The degree of improvement produced by using two separated satellites in the different environments, in terms of bit rate and probability of the received power is gi

ISSN:0737-2884    

DOI:10.1002/sat.4600100304

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

年代:1992

数据来源: WILEY

ISSN:0737-2884    

DOI:10.1002/sat.4600100301

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

年代:1992

数据来源: WILEY