Frequency of Arrival-based Interference Localization Using a Single Satellite

in 8th Advanced Satellite Multimedia Systems Conference 14th Signal Processing for Space Communications Workshop (2016, September)

Intentional and unintentional interferences are an increasing threat for the satellite communications industry. In this paper, we aim to localize an interference with unknown location using frequency of ... [more ▼]

Intentional and unintentional interferences are an increasing threat for the satellite communications industry. In this paper, we aim to localize an interference with unknown location using frequency of arrival (FoA) technique by only relying on the measurements obtained through a single satellite. In each time instance, the satellite samples the interference and forwards it to the gateway to estimate its frequency. Since the satellite moves, each estimated frequency includes a Doppler shift, which is related to the location of the unknown interferer. The satellite's position, velocity, oscillator frequency, and the interference frequency are used at the gateway to build a location-related equation between the estimated frequency and the location of the unknown interference. Simultaneously with the interference signal, the satellite samples a reference signal to calibrate the estimated frequency and compensate for the mismatches between the available and real values of the satellite's position, velocity, and oscillator frequency. Multiple location-related equations obtained based on the FoA measurements, (at least two), along with the equation of the earth surface are used to localize the unknown interference. Simulations show that increasing the number of these equations, and the satellite velocity can improve the localization accuracy by 80% and 95%, respectively. [less ▲]

GEO Satellite Feeder links and Terrestrial Full-Duplex Small Cells: A case for Coexistence

in Proceedings of 83rd IEEE VTC (Spring 2016) (2016, May)

The demand for wider bandwidths has motivated the need for wireless systems to migrate to higher frequency bands. In line with this trend is an envisaged deployment of Ka-band (or mmWave) cellular ... [more ▼]

The demand for wider bandwidths has motivated the need for wireless systems to migrate to higher frequency bands. In line with this trend is an envisaged deployment of Ka-band (or mmWave) cellular infrastructure. Further, to improve the spectral efficiency, developing full-duplex radio transceivers is gaining momentum. In view of this move, the paper proposes the possibility of reusing the satellite feeder uplink band in the full-duplex small cells. The motivation for such a reuse is two-fold :(a) there is virtually no interference from the small cells to the incumbent in-orbit satellite receiver, and (b) directive feeder antennas, with possibly additional isolation and processing causing negligible interference to the small cells. The presented interference analysis clearly supports the proposed coexistence. [less ▲]

Cooperative Estimation of Power and Direction of Transmission for a Directive Source

in IEEE Transactions on Cognitive Communications and Networking (2016)

Reliable spectrum cartography of directive sources depends on an accurate estimation of the direction of transmission (DoT) as well as the transmission power. Joint estimation of power and DoT of a ... [more ▼]

Reliable spectrum cartography of directive sources depends on an accurate estimation of the direction of transmission (DoT) as well as the transmission power. Joint estimation of power and DoT of a directive source using ML estimation techniques is considered in this paper. We further analyze the parametric identifiability conditions of the problem, develop the estimation algorithm, and derive the Cramer-Rao-Bound (CRB) for the two situations: a) where the source signal is known to the sensors, and b) where the sensors are not aware of the source signal but its distribution. Particularly, we devise a specific sensor placement/selection setup for the symmetric antenna patterned sources which leads to identifiability of the problem. Finally, numerical results verifies the efficiency and accuracy of the provided estimation algorithms in this paper. [less ▲]

Hybrid Analog-Digital Transceiver Designs for Cognitive Radio Millimiter Wave Systems

in Hybrid Analog-Digital Transceiver Designs for Cognitive Radio Millimiter Wave Systems (2016)

Recent advances in Milimeter wave (mmWave) band mobile communications may provide solutions to the increasing traffic demand in modern wireless systems. Even though mmWave bands are scarcely occupied, the ... [more ▼]

Recent advances in Milimeter wave (mmWave) band mobile communications may provide solutions to the increasing traffic demand in modern wireless systems. Even though mmWave bands are scarcely occupied, the design of a prospect transceiver should guarantee the efficient coexistence with the incumbent services in these bands. To that end, in this paper, two underlay cognitive transceiver designs are proposed based on a hybrid Analog/Digital transceiver architecture that enables the mmWave spectrum access while controlling the interference to the incumbent users with low hardware complexity and power consumption. The first cognitive solution designs a codebook free cognitive hybrid pre-coder by maximizing the mutual information between its two ends subject to interference, power and hardware constraints related to the analog counterpart. The second solution is codebook based and exhibits less complexity than the first one at the cost of inferior spectral efficiency. A novel codebook free solution for the post-coder at the cognitive receiver part is further proposed, based on a hardware constrained Minimum Mean Square Error criterion. Simulations study the performance of both the proposed hybrid approaches and compare it to the one of a fully digital solution for typical wireless environments. [less ▲]

On-board the Satellite Interference Detection with Imperfect Signal Cancellation

in 2016 IEEE 17th International Workshop on Signal Processing Advances in Wireless Communications (SPAWC) (2016)

Interference issues have been identified as a threat for satellite communication systems and services, resulting in throughput degradation and revenue loss to the satellite operators. In this context, an ... [more ▼]

Interference issues have been identified as a threat for satellite communication systems and services, resulting in throughput degradation and revenue loss to the satellite operators. In this context, an on-board spectrum monitoring unit (SMU) can be used to detect interference reliably. Current satellite SMUs are deployed on the ground and the introduction of an in-orbit SMU can bring several benefits, e.g. simplifying the ground based station in multibeam systems. This paper proposes a two-step algorithm for on-board interference detection, exploiting the frame structure of DVB-S2X standard, which employs pilot symbols for data transmission. Assuming that the pilot signal is known at the receiver, it can be removed from the total received signal. Then, an Energy Detection (ED) technique can be applied on the remaining signal in order to decide the presence or absence of interference. The simulation results show that the proposed technique outperforms the conventional ED in low interference-to-signal and noise ratios (ISNRs). [less ▲]

Cognitive approaches to enhance spectrum availability for satellite systems

in International Journal of Satellite Communications and Networking (2016)

Cognitive radio technologies have achieved in the recent years an increasing interest for the possible gain in terms of spectrum usage with respect to unshared approaches. While most of the attention has ... [more ▼]

Cognitive radio technologies have achieved in the recent years an increasing interest for the possible gain in terms of spectrum usage with respect to unshared approaches. While most of the attention has been devoted to the cognitive coexistence between terrestrial systems, the coexistence between terrestrial and satellite communications is also seen as a viable option. Cognitive radio for satellite communications (CoRaSat) has been a European Commission seventh Framework Program project funded under the ICT Call 8. CoRaSat aimed at investigating, developing, and demonstrating cognitive radio techniques in satellite communication systems for flexible and dynamic spectrum access. In this paper, the CoRaSat cognitive approaches and techniques, investigated, developed, and demonstrated as most relevant to satellite communications, are described. In particular, the focus is on spectrum awareness, that is, database and spectrum sensing approaches, and on spectrum exploitation algorithms, that is, resource allocation and beamforming algorithms, to enable the use of spectrum for satellite communications using shared bands. [less ▲]

Resource Allocation for Cognitive Satellite Communications with Incumbent Terrestrial Networks

in IEEE Transactions on Cognitive Communications and Networking (2015)

The lack of available unlicensed spectrum together with the increasing spectrum demand by multimedia applications has resulted in a spectrum scarcity problem, which affects Satellite Communications ... [more ▼]

The lack of available unlicensed spectrum together with the increasing spectrum demand by multimedia applications has resulted in a spectrum scarcity problem, which affects Satellite Communications (SatCom) as well as terrestrial systems. The goal of this paper is to propose Resource Allocation (RA) techniques, i.e. carrier, power and bandwidth allocation, for a cognitive spectrum utilization scenario where the satellite system aims at exploiting the spectrum allocated to terrestrial networks as the incumbent users without imposing harmful interference to them. In particular, we focus on the microwave frequency bands 17.7-19.7 GHz for the cognitive satellite downlink and 27.5-29.5 GHz for the cognitive satellite uplink, although the proposed techniques can be easily extended to other bands. In the first case, assuming that the satellite terminals are equipped with multiple Low Block Noise Converters (LNB), we propose a joint beamforming and carrier allocation scheme to enable cognitive Space-to-Earth communications in the shared spectrum where Fixed Service (FS) microwave links have priority of operation. In the second case, however, the cognitive satellite uplink should not cause harmful interference to the incumbent FS system. For the latter, we propose a Joint Power and Carrier Allocation (JPCA) strategy followed by a bandwidth allocation scheme which guarantees protection of the terrestrial FS system while maximizing the satellite total throughput. The proposed cognitive satellite exploitation techniques are validated with numerical simulations considering realistic system parameters. It is shown that the proposed cognitive exploitation framework represents a promising approach for enhancing the throughput of conventional satellite systems. [less ▲]

Secrecy Energy Efficiency Optimization for MISO and SISO Communication Networks

in The 16th IEEE International Workshop on Signal Processing Advances in Wireless Communications (SPAWC) (2015, June 28)

Energy-efficiency, high data rates and secure communications are essential requirements of the future wireless networks. In this paper, optimizing the secrecy energy efficiency is considered. The optimal ... [more ▼]

Energy-efficiency, high data rates and secure communications are essential requirements of the future wireless networks. In this paper, optimizing the secrecy energy efficiency is considered. The optimal beamformer is designed for a MISO system with and without considering the minimum required secrecy rate. Further, the optimal power control in a SISO system is carried out using an efficient iterative method, and this is followed by analyzing the trade-off between the secrecy energy efficiency and the secrecy rate for both MISO and SISO systems. [less ▲]

Joint Carrier Allocation and Beamforming for Cognitive SatComs in Ka-band (17.3-18.1 GHz)

in Proceedings of International Conference on Communications (2015, June)

Herein, we study the spectral coexistence of Geostationary (GEO) Fixed Satellite Services (FSS) downlink and Broadcasting Satellite Services (BSS) feeder links in the Ka-band (17.3 − 18.1 GHz) which is ... [more ▼]

Herein, we study the spectral coexistence of Geostationary (GEO) Fixed Satellite Services (FSS) downlink and Broadcasting Satellite Services (BSS) feeder links in the Ka-band (17.3 − 18.1 GHz) which is primarily allocated for BSS feeder links. Firstly, a novel cognitive spectrum exploitation framework is proposed in order to utilize the available band efficiently. Subsequently, based on the interference analysis carried out between these systems, two cognitive approaches, namely Carrier Allocation (CA) and Beamforming (BF), are investigated under the considered framework assuming the availability of an accurate Radio Environment Map (REM). The employed techniques allow the flexibility of using additional shared carriers for the FSS downlink system along with the already available exclusive carriers (19.7 − 20.2 GHz), thus increasing the overall system throughput. It is shown that a significant improvement in the per beam throughput as well as in the beam availability can be achieved by applying CA and BF approaches in the considered scenario. [less ▲]

Cognitive Spectrum Utilization in Ka Band Multibeam Satellite Communications

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 ▲]