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Comparison of measured rain attenuation in the 10.982-GHz band with predictions and sensitivity analysis

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SUMMARY

The campaign to collect rain attenuation data on terrestrial links had commenced in Malaysian tropical climates for almost two decades. The terrestrial data so far collected have been greatly utilized to derive useful statistics for various microwave applications, such as frequency scaling, rain rate conversion factor, 1-min rain rate contour maps, wet antenna losses, and fade slope duration analysis. However, there is still severe scarcity of rain attenuation data on earth–space links in Malaysia. The results of the 2-year measurement (January 2009–December 2010) of rain rates and rain-induced attenuation in vertically polarized signals propagating at 10.982 GHz have been presented in this paper. The rain attenuation over the link path was measured at Islamic International University Malaysia and compared with ITU-R P.618-10 and Crane global models in this paper.

Abdulrahman, Y., Rahman, T. A., Islam, R. M., Olufeagba, B. J. and Chebil, J. “Comparison of measured rain attenuation in the 10.982-GHz band with predictions and sensitivity analysis” Wiley, 22 June 2014. Web. 23 June 2014.

http://onlinelibrary.wiley.com/doi/10.1002/sat.1082/abstract

Exploiting cognitive radios for reliable satellite communications

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SUMMARY

Satellite transmissions are prone to both unintentional and intentional RF interference. Such interference has significant impact on the reliability of packet transmissions. In this paper, we make preliminary steps at exploiting the sensing capabilities of cognitive radios for reliable satellite communications. We propose the use of dynamically adjusted frequency hopping (FH) sequences for satellite transmissions. Such sequences are more robust against targeted interference than fixed FH sequences. In our design, the FH sequence is adjusted according to the outcome of out-of-band proactive sensing, carried out by a cognitive radio module that resides in the receiver of the satellite link. Our design, called out-of-band sensing-based dynamic FH, is first analyzed using a discrete-time Markov chain (DTMC) framework.

Abdel-Rahman, M. J., Krunz, M. and Erwin, R. “Exploiting cognitive radios for reliable satellite communications” Wiley, 22 June 2014. Web. 23 June 2014.

http://onlinelibrary.wiley.com/doi/10.1002/sat.1083/abstract

A pre-emption framework for UMTS compatible satellite system supporting multimedia traffic

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SUMMARY

The pre-emption procedure is an important part of the radio resource management when dealing with the emergency traffic. It allows resources to be allocated to higher priority connections by pre-empting lower priority connections. The provision of the pre-emption mechanism becomes much more important in the case of satellite systems such as the Inmarsat Broadband Global Area Network system, which aids in providing the communication during a catastrophe. This paper focuses on the pre-emption framework for a Universal Mobile Telecommunications System-based satellite systems. Three algorithms have been proposed, Greedy, SubSetSum and Fuzzy pre-emption algorithm. Extensive simulations are carried out for the three algorithms, and their performances are compared against each other.

Pillai, A., Hu Y.-F., and Halliwell R. “A pre-emption framework for UMTS compatible satellite system supporting multimedia traffic” Wiley, 10 June 2014. Web. 10 June 2014.

http://onlinelibrary.wiley.com/doi/10.1002/sat.1080/abstract

An improved authentication scheme for mobile satellite communication systems

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SUMMARY

Recently, Lee et al. proposed a simple and efficient authentication scheme for mobile satellite communication systems. However, we find that their scheme is vulnerable to the smart card loss attack, the denial of service attack and the replay attack. To overcome the weaknesses of Lee et al.’s scheme, we proposed an authentication scheme for mobile satellite communication systems to improve security.

Zhang, Y., Chen J., and Huang B. “An improved authentication scheme for mobile satellite communication systems” Wiley, 10 June 2014. Web. 10 June 2014.

http://onlinelibrary.wiley.com/doi/10.1002/sat.1079/abstract

Experimental detection of mobile satellite transmissions with cyclostationary features

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ABSTRACT

One of the important functions of cognitive radio (CR) technology is spectrum sensing. The implementation of an efficient spectrum sensing function can be quite challenging because of various factors such as multi-path fading, low signal-to-noise ratio of the radio communication services to be detected and the requirement to detect and analyze the signal in a short time. As a consequence, it is important to quantitatively assess the performance of spectrum sensing techniques in various scenarios. This paper investigates different digital signal processing techniques for spectrum sensing in the context of mobile satellite transmissions: power sensing, cyclostationary sensing, efficient cyclostationary sensing based on FFT accumulation method and strip spectral correlation algorithm. This paper presents experimental results on the cyclostationary properties of GSM Thuraya mobile satellite communications in various conditions both for the uplink and downlink channels. The receiver operating characteristics are computed, and the results are presented for different algorithms and different positions of the satellite terminals. The experimental results show that the cyclostationary-feature-based detection can be robust compared to energy-based technique for low signal-to-noise ratio levels. Copyright © 2014 John Wiley & Sons, Ltd.

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Different techniques for spectrum sensing in the context of mobile satellite transmissions were investigated: power sensing, cyclostationary sensing and efficient cyclostationary sensing based on FFT accumulation method and strip spectral correlation algorithm. The experimental results on the cyclostationary properties of GSM Thuraya mobile satellite communications in various conditions both for the uplink and downlink channels show that the sensing on the basis of cyclostationary features can be robust compared with energy-based technique for low signal to noise ratio levels.’

The combined automatic repeat request and rate control mechanism in S-band mobile interactive multimedia asynchronous return link—design background, parameter dimensioning and first experimental results

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SUMMARY

In the S-band mobile interactive multimedia specification, an asynchronous access using Enhanced Spread Spectrum Aloha random access has been defined for occasional messaging applications. This access scheme is complemented by a combined automatic repeat request and terminal rate control mechanism that is described in this paper. Furthermore, a queuing theory-based model is developed to describe the behaviour of the automatic repeat request mechanism, and performance results from the first proof-of-concept implementation are presented. Copyright © 2014 John Wiley & Sons, Ltd.

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This paper presents the joint automatic repeat request and terminal rate control mechanism that have been defined for the S-band mobile interactive multimedia standard. A model based on queuing theory is developed to dimension the automatic repeat request parameters and understand the QoS boundaries of S-band mobile interactive multimedia. Furthermore, first experimental results are presented.

Enhanced spread Aloha physical layer design and performance

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SUMMARY

This paper describes the key design and performance aspects of the Enhanced Spread Spectrum Aloha (E-SSA) physical layer, which represents an essential component of the S-band Mobile Interactive Multimedia European Telecommunication Institute standard. Thanks to advanced signal processing at the gateway side, the E-SSA random access protocol allows to achieve unprecedented spectral efficiency in a pure asynchronous random access mode with high robustness against received packets power unbalance. The E-SSA physical layer is closely derived from the Third Generation Partnership Wideband Code Division Multiple Access random access channel physical layer with some adaptation to best operate in the Land Mobile Satellite channels. Particular emphasis is devoted to the E-SSA physical layer system design drivers as well to the packet transmission control policies, which are of high relevance for S-band Mobile Interactive Multimedia. The demodulator architectural design is also illustrated jointly with some of the key detection performance. Finally, the E-SSA random access protocol performance are reported for Additive White Gaussian Noise and satellite mobile channels. Copyright © 2014 John Wiley & Sons, Ltd.

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This paper describes the key design and performance aspects of the Enhanced Spread Spectrum Aloha physical layer, which represents an essential component of the S-band Mobile Interactive Multimedia European Telecommunication Institute standard. The E-SSA physical layer is closely derived from the Third Generation Partnership Wideband Code Division Multiple Access Random Access (RA) channel physical layer with some adaptation to best operate in the Land Mobile Satellite channels. The gateway exploits packet optimized Successive Interference Cancellation to boost the RA performance.

Transmission control protocol performance enhancement for mobile broadband interactive satellite communication system: a cross-layer approach

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SUMMARY

Mobile broadband interactive satellite communication system is of great interest in both academic and industrial communities. However, the conventional strict-layered protocol stack architecture and the standard TCP version perform poorly over satellite link. In this paper, we propose a comprehensive cross-layer Transmission Control Protocol (TCP) optimization architecture while considering the main factors that affect the TCP performance. In our proposed architecture, we adopt two TCP split connection performance enhancing proxies to isolate the satellite link from the terrestrial part of the broadband satellite communication system. Then, based on the proposed cross-layer architecture, we present an analytical model for the TCP throughput by taking the modulation and coding (ModCod) mode and the allocated bandwidth into account. In addition, we put forward a TCP-driven bandwidth sharing and ModCod mode optimization algorithm to maximize the TCP throughput in satellite link. Extensive simulation results illustrate that our proposed comprehensive cross-layer TCP optimization approach is able to improve the TCP throughput significantly. Copyright © 2014 John Wiley & Sons, Ltd.

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In this paper, a comprehensive cross-layer Transmission Control Protocol optimization architecture is proposed for mobile broadband interactive satellite communication system. Based on the proposed cross-layer architecture, we further present an analytical model for the TCP throughput by taking the modulation and coding (ModCod) mode and the allocated bandwidth into account. Then, a TCP-driven bandwidth sharing and ModCod mode optimization algorithm is put forward to maximize the TCP throughput in satellite link.

Metro Debuts $1M Mobile Unit For Emergency, Large Event Operations

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Transportation officials Thursday debuted a new state-of-the-art mobile command post designed to help keep bus and rail operations running smoothly in the event of an emergency.

KNX 1070’s Pete Demetriou reports Metro’s Mobile Command Center may look like a giant black mobile home from the outside, but officials say inside it’s nothing less than a rolling intelligence hub. Read More