bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ku‐Band satellite data networks using very small aperture terminals—part I: Multi‐access protocols
Authors: Raychaudhuri D. , Joseph K. 
Published: July 2007

AbstractThis two‐part paper presents a comprehensive overview on the technology of very small aperture terminal (VSAT)‐based satellite data networks, which have received increasing attention in recent years because of a combination of technical and economic factors. Ku‐band networks with customer‐premise earth‐stations can overcome the inherent local access bottleneck in wide‐area terrestrial data networks by suitably exploiting the unique multi‐access and broadcast features of satellite communication. In this part of the paper, the issue of multiple access, which is an important critical path technology in the ongoing evolution of VSAT data networks, is considered in detail. Satellite multi‐access protocols are classified in terms of channel synchronization (slotted and unslotted) and the qualitative nature of message access (fixed assigned, contention and reservation). In addition to well known techniques such as ALOHA, slotted ALOHA, tree CRA, packet CDMA and demand assigned (DAMA) TDMA, a number of new approaches to efficient unslotted access, including selective reject (SREJ) ALOHA, time‐of‐arrival CRA and locally synchronous reservation, are discussed. The general review is followed by a detailed performance comparison of a number of candidate first‐generation VSAT protocols, namely ALOHA, slotted ALOHA, SREJ‐ALOHA, DAMA with TDMA reservation access and DAMA with slotted ALOHA reservation access. The performance evaluation, based on detailed simulations with VSAT equipment and transaction traffic parameters, is summarized by curves of average delay and throughput vs. number of VSATs per channel for each of the protocols considered. Higher‐order differences in delay performance are illustrated with appropriate delay distribution results and the sensitivity of performance with respect to key equipment and traffic parameters is investigated. For the transaction traffic model under consideration, the results suggest the use of SREJ‐ALOHA among contention techniques or DAMA with slotted ALOHA reservation among controlled access alternatives. The trade‐off between contention and reservation access is shown to be more complex, depending on the combination of average delay, peak delay, transmission cost and equipment complexity suited to the particular application.In Part IITo published in the next issue
of this paper on Ku‐band VSAT networks, the issue of overall system design is considered.
Planning considerations for domestic replacement satellites
Authors: Johannsen Klaus G. 
Published: July 2007

AbstractSeveral domestic satellite systems have been more than 10 years in operation. During this time, the world has experienced a dramatic growth in communication. While the demand for more telephony and data circuits and television channels is still on the rise, new methods of signal transmission and circuit compression have been developed which may balance or reduce the need for more satellite trunk capacity. And while whole national networks are converting to digital transmission, new transmission media like optical fibre, are finding application, and may take over some of the heavy traffic routes previously carried by satellite. On the other side, business data communication between roof‐top terminals, thin route traffic to remote users, television distribution by direct satellite broadcasting are becoming more popular and satellite land mobile communication may soon be a reality.Thus the domestic satellite's role appears to be slowly changing towards thin route and mobile traffic and DBS‐type distribution and perhaps even radio position determination. System planners are adapting to the new trends in satellite communication and are trying to accommodate the various service payloads on a single satellite.This article discusses some aspects of the emerging multi‐purpose domestic satellite, which carries fixed and mobile services, TV direct broadcasting and radio position determination, in view of network digitalization, network expansion, circuit compression, synchronization. The discussion centres on transponder supply and demand, satellite replenishment, Ku‐band vs. C‐band for TV direct satellite broadcasting, choice of modulation/multiple access for mobile communication, and expected accuracy in radio position determination.
Equalization for PSK signals over non‐linear channels with non‐symmetrical frequency response
Authors: Said A. , Elrefaie A. , Kurz L. 
Published: July 2007

AbstractIn this paper, a minimum mean square error equalizer (MMSE) for receiving quadrature phase shift keyed (QPSK) signals over band‐limited non‐linear satellite channels is designed. The effect of intersymbol interference due to non‐symmetrical frequency response followed by AM/AM and AM/PM conversions are taken into account while optimizing the performance in the presence of down‐link additive white Gaussian noise.The taps gain coefficients of the equalizer are obtained using numerical methods. The average probability of error is computed for two systems: the one sample detector and the (MMSE) equalizer. It is shown that significant improvement in performance is possible by replacing the one sample detector by an MMSE equalizer.
Space radio services and WARC‐MOB‐87
Authors: Withers D. J. 
Published: July 2007

AbstractA recent conference of the ITU has agreed upon worldwide frequency allocations near 1600 MHz for communication by satellite with mobile stations on land, and has permitted the use of some aeronautical mobile‐satellite frequency bands for passengers' in‐flight telephone calls to the ground. Frequencies for systems for locating mobile stations by radio, using satellites, were allocated.
Identification of requirements for intersatellite links
Authors: Puccio A. , Saggese E. , Soprano C. 
Published: July 2007

AbstractThe intersatellite link (ISL) concept has been under evaluation for many years. It has been the subject of various European Space Agency studies, one of which is summarized here.1 The study was aimed at:
outlining a reference scenario for satellite communications in the period 1996–2005, when a new satellite generation (Eutelsat III) is expected to be operational in Europe;
analysing, within the above scenario, the opportunities for an ISL implementation;
performing a deep system analysis of the selected study cases in order to give the requirements for the first ISL generation;
evaluating a micro/millimetre wave implementation of the ISL;
evaluating an optical implementation of the ISL;
evaluating the technical and economic viability of an ISL and suggesting the best technique to be used in the first ISL generation.
The main results achieved in this analysis are that: (i) the usefulness of an early implementation of ISL has been demonstrated; (ii) verification of the system aspects in the communications networks using an ISL appears as one of the most important items; (iii) the availability of optical technologies will increase the opportunities offered to ISL implementation. From these results it is shown that a first‐generation (1995–2005) millimetre‐wave ISL would be preferable for future business systems, while a second‐generation (after 2005) optical ISL could extend the ISL field of application. It is also deemed important to have during 1995–2005 an in‐orbit experiment for optical ISL as a necessary step for a subsequent operational system.
In‐orbit demonstration of optical IOL/ISL—the silex project
Authors: Vanhove J. L. , Noeldeke C. 
Published: July 2007

AbstractThe use of optical communications for the high‐data‐rate links of the future European Data Relay System (EDRS) is receiving much attention. To confirm the feasibility of such communications links, an experimental system (SILEX) consisting of three satellites (two in geostationary orbit and one in low earth orbit) is planned for 1992 or 1993 to demonstrate both inter‐orbit link (IOL) and intersatellite link (ISL) capabilities. A detailed feasibility study was performed from January to July 1987 under a European Space Agency (ESA) contract with Matra (France) as prime contractor, ANT (West Germany), Telespazio and Selenia Spazio (Italy) as subcontractors, and contributions from Berlin (France) and Dornier (West Germany). The system is based on GaAlAs semiconductor technology (0.8 μm) with silicon avalanche photodiodes (APDs) as detectors and arrays of charge‐coupled devices (CCDs) for both acquisition and tracking sensors. The design will allow wavelength division multiplexing (WDM) and high‐data‐rate transmission to be demonstrated. The expected data rates are 120 Mb/s duplex for ISL, 1 Mb/s on the IOL forward link (GEO→LEO) and two to four simultaneous 60 or 120 Mb/s channels on the IOL return link (LEO→GEO).
Performance of optical intersatellite links
Authors: Wittig M. , Oppenhäuser G. 
Published: July 2007

AbstractThe performance of optical intersatellite links is described by a model. A significant difference between optical and microwave intersatellite links is the occurrence of so‐called burst errors. The statistics of bit error rate for an optical link are derived from simulations taking into account beam mispointing resulting from satellite motions and tracking channel noise. The effect of coding on the bit error rate is also shown. The mutual tracking system between two optical terminals located on different satellites can become unstable if the noise of the tracking loop exceeds a critical value. The results of tracking simulations are presented.
Laser diode intersatellite links: Communications subsystem
Authors: Arcidiacono A. , de Vita S. 
Published: July 2007

AbstractThis paper analyzes the critical areas in optical communications systems, placing particular emphasis on the modulation/demodulation techniques used in the ISL communications subsystem design for the ESA/PSDE programme. A 4‐PPM/QPM demodulator has been designed, and problems of implementing the system at high data rates have been addressed. Maximum likelihood demodulation techniques and slot and frame synchronization were used. An attempt was made to devise a way to achieve synchronization tracking without using unique words along data patterns. Finally, for the optical ISL the use of coding is suggested as a way to relax link budget requirements. Coding could reduce problems caused by pointing subsystem instabilities. The use of on‐board soft decoding without system bandwidth expansion is also foreseen.
On‐ground testing of a full‐scale homodyne CO2 laser transceiver for free‐space communications applications
Authors: Reiland W. , Popescu A. 
Published: July 2007

AbstractThe continuing interest in optical carriers for free‐space communications has led to the design and development of a variety of powerful communications systems. This paper describes a high‐data‐rate (140–1000 Mb/s), bidirectional CO2 laser homodyne system and the philosophy for on‐ground testing of a single transceiver package by means of a simulated counter‐terminal. The problems of laboratory testing and link down‐scaling are addressed. The simulation of the counter‐terminal and its impact on the transceiver package are discussed, along with the integration and test plan of the full‐scale laboratory breadboard model.
Fade countermeasures at Ka band for olympus
Authors: Willis M. J. , Evans B. G. 
Published: July 2007

AbstractFade countermeasure techniques that can be applied to Ka band satellite communication systems are reviewed. Considered in detail are diversity, adaptive forward error correction, fade spreading, up‐link power control and adaptive TDMA. The techniques are compared for their effectiveness at Ka band, and recommendations are made for operating systems. The two important control techniques of fade detection and fade control are discussed in terms of their ease of implementation for each countermeasure technique. Details of a planned experiment to evaluate the application of fade countermeasures to VSAT networks via the Olympus satellite are presented.
Intelsat planning and modelling software in support of IDR
Authors: Duesing Richard W. , Kelinsky Martin J. 
Published: July 2007

AbstractIn order to plan for and integrate intermediate data rate (IDR) carriers into the INTELSAT newtork, while achieving quality service with efficient use of resources, operational planning tools and transmission system models are necessary. These computer software tools and models, which have evolved and grown in parallel with the INTELSAT network, comprise numerous applications on various types of computers, including mainframe, mini and personal computer systems. This paper presents an overview of the major planning and modelling software models used at INTELSAT in support of the use of IDR digital carriers within the INTELSAT system.
A framing unit for all services
Authors: Mills Nigel 
Published: July 2007

AbstractThis article describes the P1300 IDR and IBS framing unit, designed and produced by Paradise Datacom to accompany the new generation of all‐digital satellite modems currently emerging from the modem manufacturers.The combination of framing unit and all‐digital modem gives a very flexible product, capable of fulfilling the requirements of both the IDR and IBS services, and with the entirely software controlled architecture of the framing unit, it allows for future services as yet undefined.
Understanding signals from glonass navigation satellites
Authors: Dale S. A. , Daly P. , Kitching I. D. 
Published: July 2007

AbstractIn late 1986 details of the radio‐frequency signal structure currently employed by the pre‐operational GLONASS satellite navigation system were revealed by the Satellite Communications Group at Leeds University. Since then further investigation has resulted in a successful interpretation of most of the data message transmitted on the civil code, sufficient to allow the design and construction of a GLONASS receiver capable of the same level of performance as can now be achieved with NAVSTAR GPS. Details of the message content relating to location of GLONASS satellites for the purposes of position‐fixing and time‐referencing are presented for the first time.
Prediction of rain effects on earth‐space communication links operating in the 10 to 35 GHZ frequency range
Authors: Stutzman Warren L. 
Published: July 2007

AbstractThis paper reviews the effects of precipitation on earth‐space communication links operating the 10 to 35 GHz frequency range. Emphasis is on the quantitative prediction of rain attenuation and depolarization. Discussions centre on the models developed at Virginia Tech. Comments on other models are included as well as literature references to key works. Also included is the system level modelling for dual polarized communication systems with techniques for calculating antenna and propagation medium effects. Simple models for the calculation of average annual attenuation and cross‐polarization discrimination (XPD) are presented. Calculation of worst month statistics are also presented.
Some new hybrid ARQ techniques for high error rate conditions
Authors: Benelli G. 
Published: July 2007

AbstractSome new hybrid ARQ schemes for error control in communication systems are presented in which redundancy, achieved by retransmission of a code word, is exploited to facilitate correct code‐word recovery. In the first two techniques, applicable to cases in which a code word detected in error is retransmitted several times consecutively, an error‐correcting code is used in conjunction with a normal ARQ code to enhance performance even at high error rates. These two techniques have been modified to allow application to protocols in which only one copy is sent each time a code word must be transmitted. Theoretical analysis of the protocols shows that these techniques outperform similar ARQ schemes, particularly for high error rates.
Error correcting codes for fast frequency‐hopped MFSK spread‐spectrum satellite communications under worst case jamming
Authors: Wang Q. , Guliver T. A. , Bhargava V. K. , Felstead E. B. 
Published: July 2007

AbstractSpread‐spectrum techniques such as frequency hopping (FH) have been used to reduce the vulnerability of satellite communications to jamming. In such a system, error correcting (EC) codes play an essential role. Thus a knowledge of the performance of various EC codes is necessary in order to choose an EC code and related system parameters in the design of an anti‐jam system, this paper examines the performance of various types of error correcting codes under worst case partial band noise jamming and worst case multitone jamming using fast frequency‐hopped, non‐coherent M‐ary frequency‐shift keying (NCMFSK) with optimum diversity. A comprehensive study including convolutional codes, binary and non‐binary block codes and concatenated codes has been conducted. This paper presents bit error rate (BER) performances of various error correcting codes. New candidate codes with superior anti‐jam performance are identified.
An anti‐jam packet data satellite link
Authors: Fairhurst Godred , Spracklen Tim 
Published: July 2007

AbstractWith the advent of the open systems interconnection philosophy, interworking between satellite and ground‐based data networks is rapidly becoming important. X.25 LAPB/HDLC is an important standard in this field. It defines a connection between two data switching nodes. This paper examines how a low capacity (∼kb/s) anti‐jam (A/J) satellite circuit may carry a X.25 LAPB/HDLC data link.It has been shown that use of an unmodified A/J modem employing convolutional coding gives a particularly poor performance in the presence of jamming. A study of the properties which govern the performance of a packet link has led to some recommendations for a special ‘packet mode’ for anti‐jam modems and to some suggested extensions to the data link protocol. These recommendations have been implemented in a simulator and this has revealed a performance far superior to an unmodified system. The recommendations are being implemented in a trials system, developed at the University of Aberdeen, for RSRE Defford.
An ARQ/FEC coding scheme for land mobile communication
Authors: Ferebee I. C. , Tait D. J. , Taylor D. H. 
Published: July 2007

AbstractThis paper describes the development of a laboratory test unit that implements a new Type I/II ARQ scheme for use on a land mobile forward satellite link. Investigation of channel characteristics showed that it was possible to use convolutional coding to combat random errors, but it was also necessary to employ an ARQ scheme in order to overcome fades due to signal blockage.The hardware development used commercial 68000‐based VME cards as well as special‐purpose cards to perform the functions of Viterbi decoding and packet synchronization.Results are presented for the hardware operating with Gaussian noise as time limitations excluded the use of satellite fading simulation. In order to ensure a high degree of data integrity error detection was applied to the data packets such that a residual error rate of less than 10−11 should result. This was not able to be verified due to the limited time. However, long term tests did indicate that an error rate less than 10−8 was achieved.
Algebraic properties of BCH codes useful for decoding
Authors: Da Rocha Valdemar C. , Honary Bahram K. , Bate Steve D. 
Published: July 2007

AbstractIn this paper theorems are presented which allow the simplified decoding of (n, k, δ) BCH codes in certain cases of practical interest. Such results are in a way implicit in the theory of BCH codes, but so far have not appeared explicitly in the literature. It is shown that any t0 errors, 1 ⩽ t0 ⩽ δ‐1, can be detected by using any set of only t0 consecutive coefficients of the syndrome polynomial. The correction of any t0 errors, 1 ⩽ t0 ⩽ [(δ‐1)/2], can be performed by using any set of 2t0 consecutive coefficients of the syndrome polynomial, where [x] means the integer part of x. Similar results are derived for punctured BCH codes. In this case sets of t0 or 2t0 consecutive coefficients, respectively, for detecting or correcting t0 errors, are selected from the δ‐1‐p higher‐order coefficients of the modified syndrome polynomial, where p is the number of digits punctured from a code word. These results hold true even when the punctured digits are not consecutive.
Review of saw devices and their signal processing applications in space communications
Authors: Ananasso Fulvio 
Published: July 2007

AbstractAn increasing number of advanced signal processing techniques are being investigated in satellite communications systems as the ground and space segments require more and more sophisticated, light‐weight, low‐power‐consumption and cost‐effective equipment.RF signal processing techniques based on surface acoustic wave (SAW) devices can be suitably exploited in these systems, constituting a valid alternative to digital baseband processing.This paper aims at presenting the most recent applications of SAW devices to RF signal processing in satellite communication systems. They span the frequency range from about 10 MHz to 10 GHz. Interaction of SAWs with laser beams is also illustrated.
Routeing and filtering in the ETS‐V transponder for mobile communication experiments
Authors: Kondo K. , Hashimoto Y. , Ide T. 
Published: July 2007

AbstractThe Japanese spacecraft ETS‐V implemented an experimental mobile satellite communication system via a transponder called AMEX (aeronautical maritime experimental transponder). L‐band was used for the mobile link and C‐band for the feeder link. For the L‐band two‐beam system routeing and filtering were performed through 12 SAW filters and four switches in the IF part. The effective frequency allocation plan was obtained considering the features of the links used and the characteristics of SAW filters. The filtering to prevent EMC problems was also studied for AMEX, which handles high‐ and low‐level signals simultaneously. AMEX shows good performance in orbit and is being used for a variety of mobile communication experiments by many organizations including the Communications Research Laboratory.
Signal suppression effects in an ideal hard‐limiter for the many‐carrier case
Authors: Comparetto G. M. 
Published: July 2007

AbstractAn analytical expression, previously derived in a companion paper published in Volume 7, Issue No. 1 of the International Journal of Satellite Communications (pp. 3–6), was used to generate signal suppression data for 3, 5, 10, 20, 40 and 55 input signal scenarios in the presence of Gaussian noise assuming an ideal hard‐limiter for a wide range of input signal ratios. Additionally, the signal suppression effect has been quantified for up to 200 input signals with input SNRs of ∞, 6 dB and 0 dB for the case in which a single higher‐power input signal exists in the presence of lower, equal‐powered signals. The data support the argument that the signal suppression effect is significantly reduced as the number of input signals is increased for the scenarios investigated. Also, the generated data show that the signal suppression effect decreases asymptotically to a value less than 1 dB for the case of a single higher‐power signal in the presence of varying degrees of input Gaussian noise and up to 200 total signals. Finally, a Gaussian approximation of the input signal ensemble was verified for the full range of input signal sets investigated.