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Monthly Archives: June 2014

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.

Thumbnail image of graphical abstract

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.’