References of "Liolis, Konstantinos"
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See detailOptical Feeder Links Study towards Future Generation MEO VHTS Systems
Mengali, Alberto UL; Lyras, Nikos K.; Shankar, Bhavani UL et al

in Proceedings of the 35th AIAA International Communications Satellite Systems Conference (ICSSC) (2017, October)

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See detailSimultaneous Sensing and Transmission for Cognitive Radios with Imperfect Signal Cancellation
Politis, Christos UL; Maleki, Sina UL; Tsinos, Christos UL et al

in IEEE Transactions on Wireless Communications (2017)

In conventional cognitive radio systems, the secondary user employs a “listen-before-talk” paradigm, where it senses if the primary user is active or idle, before it decides to access the licensed ... [more ▼]

In conventional cognitive radio systems, the secondary user employs a “listen-before-talk” paradigm, where it senses if the primary user is active or idle, before it decides to access the licensed spectrum. However, this method faces challenges with the most important being the reduction of the secondary user’s throughput, as no data transmission takes place during the sensing period. In this context, the idea of simultaneous spectrum sensing and data transmission is proposed. The present work studies a system model where this concept is obtained through the collaboration of the secondary transmitter with the secondary receiver. First, the secondary receiver decodes the signal from the secondary transmitter, subsequently, removes it from the total received signal and then, carries out spectrum sensing in the remaining signal in order to decide about the presence/absence of the primary user. Different from the existing literature, this paper takes into account the imperfect signal cancellation, evaluating how the decoding errors affect the sensing reliability and derives the analytical expressions for the probability of false alarm. Finally, numerical results are presented illustrating the accuracy of the proposed analysis. [less ▲]

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See detailCognitive Spectrum Utilization in Ka Band Multibeam Satellite Communications
Maleki, Sina UL; Chatzinotas, Symeon UL; Evans, Barry et al

in IEEE Communications Magazine (2015), 53(3), 24-29

Multibeam satellite networks in Ka band have been designed to accommodate the increasing traffic demands of the coming years. However, these systems are spectrum limited due to the current spectrum ... [more ▼]

Multibeam satellite networks in Ka band have been designed to accommodate the increasing traffic demands of the coming years. However, these systems are spectrum limited due to the current spectrum allocation policies. This paper investigates the potentials of applying cognitive radio techniques in satellite communications in order to increase the spectrum opportunities for future generation of satellite networks without interfering operation of incumbent services. These extra spectrum opportunities can potentially amount to 2.4 GHz of bandwidth in downlink, and to 2 GHz of bandwidth in uplink for high density fixed satellite services (HDFSS). [less ▲]

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See detailCognitive Zone for Broadband Satellite Communication in 17.3-17.7 GHz Band
Maleki, Sina UL; Chatzinotas, Symeon UL; Krause, Jens et al

in IEEE Wireless Communications Letters (2015)

Deploying high throughput satellite systems in Ka band to accommodate the ever increasing demand for high data rates hits a spectrum barrier. Cognitive spectrum utilization of the allocated frequency ... [more ▼]

Deploying high throughput satellite systems in Ka band to accommodate the ever increasing demand for high data rates hits a spectrum barrier. Cognitive spectrum utilization of the allocated frequency bands to other services is a potential solution. Designing a cognitive zone around incumbent broadcasting satellite service (BSS) feeder links beyond which the cognitive fixed satellite service (FSS) terminals can freely utilize the same frequency band is considered in this paper. In addition, we show that there is a rain rate called rain wall, above which cognitive downlink communications becomes infeasible. [less ▲]

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See detailSpatial Multiplexing in Optical Feeder Links for High Throughput Satellites
Gharanjik, Ahmad UL; Liolis, Konstantinos; Shankar, Bhavani UL et al

in Spatial Multiplexing in Optical Feeder Links for High Throughput Satellites (2014, December 02)

Optical feeder links are an attractive alternative to the RF feeder links in satellite communications (SatCom). In this paper, we present initial results from an optical feeder link study. We discuss the ... [more ▼]

Optical feeder links are an attractive alternative to the RF feeder links in satellite communications (SatCom). In this paper, we present initial results from an optical feeder link study. We discuss the architecture of a geostationary earth orbit (GEO) satellite system based on optical feeder links. To mitigate the effects of cloud coverage, which is the main availability-limiting factor, Optical Ground Station (OGS) diversity is employed. Moreover, a spatial multiplexing scheme is considered. Assuming an ON-OFF channel model, the number of required OGSs to ensure availability and throughput requirements is analyzed [less ▲]

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See detailCognitive Radio for Ka Band Satellite Communications
Maleki, Sina UL; Chatzinotas, Symeon UL; Sharma, Shree Krishna UL et al

in 32nd AIAA International Communications Satellite Systems Conference, August 2014 (2014, August)

The satellite communication data traffic is increasing dramatically over the coming years. High throughput multibeam satellite networks in Ka band are potentially able to accommodate the upcoming high ... [more ▼]

The satellite communication data traffic is increasing dramatically over the coming years. High throughput multibeam satellite networks in Ka band are potentially able to accommodate the upcoming high data rate demands. However, there is only 500 MHz of exclusive band for download and the same amount for upload. This spectrum shortage impose a barrier in order to satisfy the increasing demands. Cognitive satellite communication in Ka band is considered in this paper in order to potentially provide an additional 4.4 GHz bandwidth for downlink and uplink fixed-satellite-services. In this way, it is expected that the problem of spectrum scarcity for future generation of satellite networks is alleviated to a great extent. The underlying scenarios and enabling techniques are discussed in detail, and finally we investigate the implementation issues related to the considered techniques. [less ▲]

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