Let's Communicate
We want to hear from you.

Category Archives: Industry News

In-line interference mitigation techniques for spectral coexistence of GEO and NGEO satellites

By | Industry News | No Comments

SUMMARY

The interest towards the deployment of Low Earth Orbit (LEO)/Medium Earth Orbit (MEO) satellite systems in several frequency bands is increasing due to the requirement of low latency for real-time systems and high demand of broadband data. When the number of usable Non-Geostationary (NGEO) satellites, that is, LEO/MEO in space, increases, the frequency coexistence between the NGEO satellite systems with the already existing geostationary (GEO) satellite networks becomes a requisite. In this context, it is crucial to explore interference mitigation techniques between GEO and NGEO systems in order to allow their spectral coexistence. More specifically, in the coexistence scenario of GEO and NGEO satellite networks, in-line interference may be a serious problem, especially in the equatorial region. In this paper, we provide several frequency sharing studies in the context of the coexistence of an NGEO satellite link with another NGEO/GEO satellite link.

Sharma S. K. Chatzinotas S. and Ottersten. “In-line interference mitigation techniques for spectral coexistence of GEO and NGEO satellites” Wiley, 9 September 2014. Web. 10 September 2014.

http://onlinelibrary.wiley.com/doi/10.1002/sat.1090/abstract

Analysis and performance evaluation of new coding options for space telecommand links – Part I: AWGN channels

By | Industry News | No Comments

We investigate and compare, over the additive white Gaussian noise channel, different options for updating the error correcting code currently used in space mission telecommand links. Besides some more consolidated proposals, using low-density parity-check codes, we characterize and assess the performance of alternative schemes, based on parallel turbo codes and soft-decision decoded Bose-Chaudhuri-Hocquenghem (BCH) codes.

Baldi M., Chiaraluce F., Garello R., Maturo N., Aguilar Sanchez I., and Cioni S. “Analysis and performance evaluation of new coding options for space telecommand links – Part I: AWGN channels” Wiley, 9 September 2014. Web. 9 September 2014.

http://onlinelibrary.wiley.com/doi/10.1002/sat.1092/abstract

Analysis and performance evaluation of new coding options for space telecommand links – part II: jamming channels

By | Industry News | No Comments

SUMMARY

In this paper, we study the performance of telecommand space links affected by pulsed, continuous wave and pseudo-noise jamming. Countermeasures include coding, interleaving, and direct sequence spread spectrum. Binary and non-binary low-density parity-check codes, parallel turbo codes, and soft-decision decoded BCH codes are considered. We investigate the impact of different decoding algorithms, also taking into account the role of jamming state information, spreading processing gain and interleaving. The results show that significant gains (up to more than 10 dB) can be achieved in a number of interesting scenarios.

Baldi M., Chiaraluce F., Garello R., Maturo N., Aguilar Sanchez I. and Cioni S. “Analysis and performance evaluation of new coding options for space telecommand links – part II: jamming channels” Wiley, 8 September 2014. Web. 8 September 2014.

http://onlinelibrary.wiley.com/doi/10.1002/sat.1091/abstract

Efficient dynamic authentication for mobile satellite communication systems without verification table

By | Industry News | No Comments

SUMMARY

The mobile satellite system is an important wireless communication system widely used nowadays. The issue of protecting the transmission security in low-earth-orbit satellite networks thus becomes more and more critical. It is known that several authentication schemes for satellite communication systems have been proposed to deal with the issue. However, previous protocols either employ complicated public key computation or have to maintain a verification table. In this paper, the author will introduce a new dynamic authentication protocol for mobile satellite communication systems without using a verification table.

Lin H.-Y. “Efficient dynamic authentication for mobile satellite communication systems without verification table” Wiley, 8 September 2014. Web. 8 September 2014.

http://onlinelibrary.wiley.com/doi/10.1002/sat.1088/abstract

Early detection and rejection probability-based congestion control scheme for deep space networks

By | Industry News | No Comments

Summary

Deep Space Networks (DSNs) are a class of DTNs. In such networks, owing to limited radio range and node mobility, end-to-end paths between source and destination nodes are not available. Messages are relayed by store-and-forward strategy and may be buffered for long periods before being forwarded to the next hop. Therefore, the buffer of message carriers may overflow, and congestion follows. To address this issue, this paper proposes an early detection and rejection probability-based congestion control algorithm, named ERBA, in which every intermediate node estimates rejection probability when a new message arrives and refuses to receive the message with the rejection probability, so as to avoid congestion. To validate its effectiveness, ERBA is merged into static routing (SR) and dynamic routing (DR). SR and DR are classical routing algorithms for DSNs. The simulation results show that when working with ERBA, the routing overhead of SR and DR decreases rapidly.

Y Jiang G. Shen Y. and Chen J. “Early detection and rejection probability-based congestion control scheme for deep space networks” Wiley, 5 September 2014. Web. 5 September 2014.

http://onlinelibrary.wiley.com/doi/10.1002/sat.1094/abstract

Satellite interference evaluation: joint effect of modeling earth station locations and earth station antenna sidelobe gains as random variables

By | Industry News | No Comments

SUMMARY

When several satellite communication systems share the same frequency band, each system operates under the aggregate interference generated by the others. In this interfering environment, interference calculation procedures in which worst-case situations and simplifying assumptions are considered are commonly used. Given that the geostationary satellite orbit and the frequency spectrum are limited resources, it is important to consider alternatives that lead to a more precise interference evaluation. One of these alternatives is the use of a probabilistic methodology, in which some of the parameters involved are modeled as random variables. This work considers the specific case in which the earth station geographic locations and the sidelobe gains of their antennas are modeled as random.

Tamo, A. and Fortes, J. M. P. “Satellite interference evaluation: joint effect of modeling earth station locations and earth station antenna sidelobe gains as random variables” Wiley, 3 September 2014. Web. 3 September 2014.

http://onlinelibrary.wiley.com/doi/10.1002/sat.1089/abstract

QoS provisioning by power control for video communication via satellite links

By | Industry News | No Comments

SUMMARY

Video transmissions over satellite links are sensitive to signal fades because of rain, especially in the tropics. We performed a video-streaming experiment over a satellite link for 24 days distributed over 1 year to investigate the effects of rain fade. Based on the measurements, models for the relationships between rainfall rate, power level, packet loss, and video quality are proposed. Furthermore, for both uplink and downlink channel, an adaptive closed loop power control algorithm, with a Proportional–Integral–Derivative controller is designed. This is used for the mitigation of the rain-induced attenuation in order to guarantee a certain level of Quality of Service and Quality of Experience.

Ma T., Lee Y. H., Winkler S. and Ma M. “QoS provisioning by power control for video communication via satellite links” Wiley, 1 September 2014. Web. 2 September 2014.

http://onlinelibrary.wiley.com/doi/10.1002/sat.1087/abstract

Welcome to our Satellite Blog

By | Industry News, Satellite Blog | No Comments

In the context of spaceflight, a satellite is an artificial object which has been intentionally placed into orbit. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon. The world’s first artificial satellite, the Sputnik 1, was launched by the Soviet Union in 1957. Since then, thousands of satellites have been launched into orbit around the Earth. Read More