Single Channel Per Carrier Research Articles

Design and Simulation of Ground Station (GS) Television Channel (TV CH) Group

The Multiple Channel per Carrier (MCPC) is considered an efficient alternative when used in Ground Station (GS) TV channel stations as it accommodate multiple channel on a limited frequency range. The MCPC technique has been widely used worldwide due to its efficiency. The MCPC technique offers exemplary performance over the traditionally Single channel Per Carrier (SCPC) when considering system accuracy, time, and cost. In this study, the MCPC static mode technique has been investigated using MATLAB tool to simulate a four TV CH system. The GS transmitter and receiver components referenced to four explicit points representing the number of channels carried by the satellite. These components have been constructed and observed using Spectrum Analyzer.

Novel MF-TDMA/SCPC switching algorithm for DVB-RCS/RCS2 return link in railway scenario

This work focuses on the return channel resource allocation in the DVB-RCS/RCS2 system for mobile terminals. A continuous carrier (CC) operation mode based on DVB-S2/S2X is considered and investigated. The paper focuses on the possibility of transmitting simultaneously in multifrequency–time division multiple access (MF-TDMA) or single channel per carrier (SCPC) medium access techniques, as suggested by a previous DVB-RCS+M standard. The introduction of this capability has also been analyzed for a new DVB-RCS2 standard that gives the possibility of using both return link (RL) modalities. Moreover, we propose a detailed study of the RL channel in a satellite platform in order to understand the operative range of SCPC and MF-TDMA techniques. The contribution seeks to provide some threshold indications to network operators for dynamically managing satellite resources.We considered the railway market, which is characterized by an N-LOS condition due to blockage caused by tunnels, vegetation, and buildings, as the reference scenario. Furthermore, we introduced a transparent gap filler (GF) solution to overcome this issue. Simulation campaigns are shown, in order to give satellite operators some guidelines, when they want to make use of this hybrid channel modality.

Link-Layer FEC and Cross-Layer Architecture for DVB-S2 Transmission With QoS in Railway Scenarios

Digital Video Broadcasting via Satellite-Second Generation (DVB-S2) was originally designed for fixed terminals, but it has recently been adopted by the DVB Return Channel via Satellite for Mobile scenario (DVB-RCS +M) under the single-carrier-per-channel (SCPC) mode. For the purpose of adapting DVB-S2 for mobile reception, it has been agreed that, among others, forward error correction (FEC) at the link layer (LL) is a suitable means of achieving reliable reception in mobile environments. Prime candidates for LL-FEC had already been available schemes in the DVB family of standards: multiple-protocol encapsulation-FEC (MPE-FEC) and MPE interburst FEC (MPE-IFEC). Furthermore, different FEC codes may be applied within these schemes, i.e., Reed-Solomon (RS) or Raptor FEC codes. This paper introduces the integration of such schemes and codes on top of DVB-S2. In addition, we analyze the performance that can be achieved when applying these schemes with particular focus on two typical railway scenarios: 1) line of sight, together with the effect of railway power arches (LOS+PA), and 2) nonline of sight (nLOS). Both theoretical and simulation analyses reveal that LL-FEC can overcome typical fading effects in the railway scenario by selecting appropriate FEC codes and optimizing the coding parameters. We show that MPE-IFEC and extended MPE-FEC with Raptor codes-as finally specified in DVB-RCS+ M-consistently show superior results over those of other LL-FEC for railway scenarios. We also indicate signaling updates to allow achievable performance. As for practical implementation, we propose two possible novel cross-layer architectures for unicast DVB-S2 to provide quality of service (QoS). The architectures allow the migration from traditional packet encapsulation based on Moving Picture Experts Group 2-Transport Streams (MPEG2-TS) to new schemes, such as generic stream encapsulation (GSE).

Effects of Tropical Rainfall to the Ku-Band Satellite Communications Links at the Equatorial Atmosphere Radar Observatory

This study investigates the effects of tropical rainfall on the Ku-band satellite communications links that connect Research Institute for Sustainable Humanosphere (RISH), Kyoto University in Japan to Equatorial Atmosphere Radar Observatory (EAR; 0.2 � S, 100.3 � E) in Indonesia, using the satellite Superbird C (144 � E in orbit). Rain attenuation of the up- and down-link radio wave signals is, for the first time, obtained at the same time in the tropics, monitoring each signal level that has been received at both stations in Japan and Indonesia for the past three years from 2003 to 2005. The up-link attenuation at each station can be estimated from the down-link signal level measured at its opposite station, because SCPC (Single Channel Per Carrier) signals used in this experiment are linearly amplified without saturation of the satellite transponders. At EAR in Indonesia, a slightly larger attenuation ratio between up and down links is statistically presented for the attenuation range of higher that 10 dB, suggesting the effects of smaller raindrop size distributions (DSD) than observed at RISH in Japan. This tendency is more conspicuous in the rainfall events when the observed attenuation shows only one peak in its time series, indicating the effects of simple convective precipitating clouds with one single cell. At RISH in Japan, a larger difference between worst month and yearly average statistics is found, due to a larger variation of the ground temperature that affects the slant-path length during the seasons, although the yearly average time percentages as such are larger at EAR than RISH up to the up-link attenuation of 15 dB. Using time percentages of their local rainfall rates, fairly good agreement is found between the observations and the ITU-R (International Telecommunication Union—Radiocommunication Sector) predictions for both locations. At EAR in Indonesia, however, the time percentages of the attenuation of more than 10 dB become significantly smaller than those predicted by the ITU-R methods for both up and down links. This indicates the remarkable reduction of equivalent path lengths down to about 2 km, caused by a fairly localized structure of convective precipitating clouds. Simultaneous X band radar observations have revealed that intense echo cores of typical rain cells causing severe attenuation

System considerations on SCPC for digital satellite receivers with direct conversion

Analog front-ends for digital satellite reception may be performed as direct conversion receivers (DCR), which do not use SAW filters. Considerations for single carrier per channel (SCPC) reception are discussed. This paper comments on the way in which baseband filtering for the DCR could be optimized. We compare the DCR with a single conversion receiver (currently used in the most concepts available in the market). Since the baseband filtering affect not only the signal selection but also the other important aspects in a tuner, like AGC, linearity behavior, dynamic range and SNR we make a more detailed overview of both concepts.

Spectrally efficient MSK scheme for SCPC communicationsystems

A spectrally efficient scheme is described, for SCPC (single channel per carrier) communication systems, in which slightly modified MSK (minimum shift keyed) channels can be allowed to overlap spectrally, with a channel spacing equal to half the individual channel bit rate, without causing any crosschannel interference.

Communications and radio determination system using two geostationary satellites. I. System and experiments

We developed two types of hybrid terminals that can provide both satellite communication and position determination services in one system. One terminal uses the single channel per carrier (SCPC) technique and the other uses the spread spectrum (SS) technique. To evaluate the performance of the two systems, we carried out experiments in Japan and in the Pacific Ocean using two geostationary satellites, ETS-V (150/spl deg/E) and Inmarsat (180/spl deg/E). The ranging accuracy between the mobile terminals and the base station via the satellites was found to be about 200 m using the SCPC system and about 10 m using the SS system. The measured positioning accuracy was about 1 km in the SCPC system and about 600 m in the SS system when experiments were carried out near Japan. The experimental results show that the positioning errors were mainly caused by the orbital determination errors of the two satellites. Presented here are the configurations and features of the SCPC and SS terminals, the experimental system, and the experimental results.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Channel-individual adaptive beamforming for mobile satellite communications

A digital frequency-division multiplex demultiplexer for single channel per carrier (SCPC) signals was developed for use in a digital channel-individual beamforming network for an adaptive satellite array antenna for mobile satellite communications. The available ASIC (35000 gate functions in CMOS technology, clock rate up to 30 MHz with low power consumption) permits the separation of FDM signals comprising up to 16 channels. Starting from a suitable model for the demultiplexer beamforming system, this paper describes the analysis, design, simulation and implementation of the hierarchically structured demultiplexer. Aspects of digital beamforming are only discussed as far as necessary for understanding. >

A multirate digital multicarrier demodulator: design, implementation, and performance evaluation

Frequency-division multiple access (FDMA) and single channel per carrier (SCPC) in the uplink and time-division multiplexing (TDM) in the downlink are employed in the system described. To interface FDMA in the uplink and TDM in the downlink, multicarrier demodulation (MCD) is required onboard the satellite. The operation of the onboard MCD is the separation of each individual channel and subsequent demodulation. The results, which concern onboard frequency demultiplexing and demodulation for low-bit-rate carriers, are constrained by the requirement that new-generation payloads could serve the stations already active in the INTELSAT Business System. A digital hardware design that implements an MCD that can process three channels at 4.4 Mb/s or 12 channels at 1.1. Mb/s is described. The test results confirm the MCD feasibility, and further improvements are expected from a semicustom implementation.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A performance analysis of DS-CDMA and SCPC VSAT networks

Spread-spectrum and single-channel-per-carrier (SCPC) transmission techniques work well in very small aperture terminal (VSAT) networks for multiple-access purposes while allowing the Earth station antennas to remain small. Direct-sequence code-division multiple-access (DS-CDMA) is the simplest spread-spectrum technique to use in a VSAT network since a frequency synthesizer is not required for each terminal. An examination is made of the DS-CDMA and SCPC Ku-band VSAT satellite systems for low-density (64-kb/s or less) communications. A method for improving the standard link analysis of DS-CDMA satellite-switched networks by including certain losses is developed. The performance of 50-channel full mesh and star network architectures is analyzed. The selection of operating conditions producing optimum performance is demonstrated. >

A dominant carrier SCPC/satellite system design

In this paper the design of a communication system that uses a dominant carrier in a two-level single channel per carrier (SCPC) system is presented. Existing international satellites, the INTELSAT system, are deployed. Since the dominant carrier increases the intermodulation distortion, the design criteria are based on the computation of the non-linear system performance. Simple expressions to give the number of intermodulation products falling in specific channels have been developed. The system carrier-to-noise power ratio is considered acceptable if found to be above the threshold value for a bit error rate of 10−4.

On‐board digital signal processing technologies for present and future SCPC systems

AbstractDevices and architectures for on‐board SCPC (single channel per carrier) multi‐carrier demodulators suitable for use in satellites to be launched between the present and the year 2000 are discussed in the light of trends in the development of device technology towards lower on‐board weight and power consumption. It is shown that at the present time (equivalent to about 1990 for on‐board use).The choice of demodulation scheme depends on the number of channels available for regeneration on board the satellite. The total weight and power consumption for several suitable on‐board multicarrier demodulation schemes are predicted for 1990, 1995 and 2000, as functions of the number of channels to be regenerated.

Comparison of two speech codecs for DMR systems

Several activities have been undertaken in Italy in the field of Digital Mobile Radio (DMR). In particular, concerning speech coding two codecs were developed to be compared on experirental Single Carrier Per Channel (SCPC) systems. These two codecs are described in the paper and their performances are compared. Both coders are based on a Split-Band (SB) structure that allows an easy exploitation of masking effects: they are a Sub-Band Coder (SBC) and SB-APC (Adaptive Predictive Coder). The main feature of both schemes is the use of Vector Quantization (VQ) to compact the side information. In addition the SB-APC scheme uses the technique of post-filtering to shape the quantizing noise of each sub-band. The main result reported in the paper is that the performances of the two schemes are almost equivalent although their structure is very different.

Onboard Digital Signal Processing Technologies for Present and Future TDMA Arid SCPC Systems

An appropriate sampling of devices and architectures for onboard TDMA (Time Division Multiple Access) equipment, burst modems, baseband switches, and SCPC (Single Channel per Carrier) multicarrier demodulators from the present to the year 2000 are selected and presented along with device technology development trends, in terms of minimizing onboard weight and power consumption. The results show that at the present time (equivalent to around the year 1990 for onboard use), onboard TDMA equipment with a clock rate of lower than 100 MHz can be reasonably realized by parallel-processed CMOS/BULK LSIC's, while for TDMA equipment with clock rates of higher than 100 MHz, bipolar devices are more appropriate. The boundary clock rate is not so rigid, and toward the year 2000, the boundary will move up to about 200 MHz. Moreover, around the year 2000, GaAs devices will be more widely used for onboard high-bit rate TDMA. It is shown that for carrier frequencies up to 2 GHz, modem implementation in monolithic microwave IC's is most suitable. Moreover, it is found that coherent demodulation will not entail a big penalty in hardware size and power consumption, because of implementing carrier recovery circuits using IC's and LSIC's. As potential baseband switch configurations, a single <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</tex> -stage and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T-S-T</tex> architecture are compared, and suitable throughputs and TDMA frame lengths for each architecture are clarified. For SCPC multicarrier demodulators, the selection of demodulation schemes depends on the number of channels available for regeneration onboard the satellite. Therefore, in this paper, for years 1990, 1995, and 2000, the total weight and power consumption for several suitable onboard multicarrier demodulation schemes are studied as a function of the number of channels to be regenerated.

Intermodulation owing to quantisation of two-carrier-level SCPC system

The quantisation of a two-carrier-level single-channel-per-carrier (SCPC) system is analysed using a simple, general approach. The quantisation staircase is represented by the sum of the input plus a sawtooth. Using an infinite Fourier series for expanding this sawtooth, closed-form expressions, in terms of the Zeta function, are obtained for the output quantised carrier and the resulting intermodulation products of any order.

A second-generation scpc system for business satellite communications

The European Telecommunications Administrations are planning to offer Business Satellite Services from the beginning of 1985. Designed under the auspices of EUTELSAT, the Satellite Multiservice System (SMS) operates in the 14/12.5 GHz bands and will use two satellites: the European Communications Satellite (ECS), and capacity leased on the French domestic satellite, Telecom 1. This paper describes the ECS SMS and in particular the Single Channel Per Carrier (SCPC) access system. This system operates over a range of data rates from 64 kbit/s to 2 Mbit/s and incorporates a number of novel features including satellite-link encryption, the use of soft-decision error correction, and full support of terrestrial interface standards.

Design considerations for a larger inmarsat standard ship earth station

AbstractA new standard of INMARSAT ship earth station for multi‐channel operation could find particular application on large passenger ships and off‐shore oil/gas platforms. This paper provides estimates of platform and ship motions and discusses general design requirements, notably of the antenna system. The discussion includes consideration of possible modulation and multiple access techniques. Single channel per carrier (SCPC) operation is advocated which permits easy integration with the present service to single channel INMARSAT Standard‐A ship earth stations. Major parameter/relative cost trade‐off curves needed in an overall ship earth station design optimization are presented.

30/20 GHz Band SCPC Satellite Communication Using Small Earth Stations

This paper presents a domestic satellite communication system accommodating numerous 30/20 GHz band small earth stations emphasizing the system outline, the use of multiple-access (MA) techniques. It also describes associated earth station configurations, equipment performance, and experimental results using the Japanese CS (medium capacity communications satellite for experimental purposes). Two kinds of earth stations are employed in this system, a small earth terminal (SET) and a master earth station (MES). The SET, which has an antenna about 2 m in diameter, is placed near a subscriber. The MES, which has an 11.5 m diameter antenna, is connected to the terrestrial telephone network through a satellite telephone switching center (STC). There are about 50 two-way channels with bit rates of 32 kbits/s which are achieved through the use of a 30/20 GHz band transponder whose EIRP is about 71.5 dBm, a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">G/T</tex> of about 2.7 dB/K and an SET's antenna diameter of 1.8 m. This results in a system availability of 99.5 percent under typical Japanese statistical rain attenuation data. To enable a demand-assigned MA technique to be employed in this system, a single channel per carrier (SCPC) is selected, taking into consideration power efficiency of the SET, flexibility of system configurations, and the adaptability of the adaptive power control during rainy periods.

Digital mobile telephone system using TD/FDMA scheme

Multiple access is an indispensable technique for efficient radio spectrum utilization in mobile radio systems, because a large number of subscribers can be connected only when they require radio channels. Frequency division multiple access (FDMA) scheme using single channel per carrier (SCPC) has been widely used. However, the SCPC-FDMA scheme has some problems, such as difficulty in setting up a large number of base station transceivers and in realizing a low-cost highly stabilized local oscillator. A time and frequency division multiple access (TD/FDMA) scheme, which is a combination scheme of TDMA and FDMA, is proposed as one of the possible solutions for these problems. After explaining the background of the proposal, some of the restrictions of the TD/FDMA scheme resulting from the land mobile radio channel characteristics are described. Basic concept of the digital mobile radio telephone system using TD/ FDMA scheme is then presented. An example of the possible system design is finally shown.

Design and Evaluation of a Convolutional Codec in Additive White Gaussian Noise, Sinusoidal Interference, and Intersymbol Interference Environment

An integrated view of the performance of a rage 3/4, forwardacting, error-correcting convolutional codec, as used on the Intelsat single channel per carrier (SCPC) satellite communication system, is presented with respect to various transmission problems. The available literature does not indicate clearly whether such a codec would have acceptable performance in an environment involving detrimental factors such as sinusoidal interference (SI) or intersymbol interference (ISI). Experimental performance evaluations are given for the cases of an additive white Gaussian noise (AWGN) environment, a pure sinusoidal interference signal, AWGN combined with SI, and finally for AWGN in an ISI environment. The results confirm that this type of codec is designed to combat random errors effectively, and not burst-type errors such as those generated by SL Further observations indicate that it is preferable to measure a codec performance in terms of bit error rate (BER) reduction for a given signal-to-noise (S/N) ratio rather than SIN reduction for a given BER since this latter method is too susceptible to the operating conditions to which the codec is submitted.