On the Physical Layer Security of IoT Devices over Satellite

Abstract

The security in satellite communications is a key issue due to the large footprint of the beams. This it is specially critical in IoT devices that transmit data directly to satellite. Take into account that IoT devices are characterized by transmitting packets of short length. Consequently, it means that it is not feasible to augment the security level of the IoT packets via complex cryptographic algorithms. Otherwise, their packed length may be increased in a non-negligible way which could augment their collision probability, latency and energy consumption. For this reason, this paper proposes to take advantage of the time-packing technique. By doing so, it is possible to use the overlapping degree among the pulse-shapes to boost the secrecy-capacity. In particular, the overlapping degree between the pulse-shapes introduces an artificial interference that degrades the eavesdropper's channel. In this regard, it is necessary to highlight that there is a residual co-channel interference in the satellite beams. So, it means that these two sources of impairments make difficult to estimate the legitimate user's transmission parameters by the eavesdropper.

On the Use of NB-IoT over GEO Satellite Systems with Time-Packed Optical Feeder Links for Over-the-Air Firmware/Software Updates of Machine-Type Terminals

“…and β = 1/σ 2 Y of the Gamma-Gamma distribution in (20) are directly related to the atmospheric conditions, and for the untracked beam case are given:…”

“…From the satellite point of view, the possibility of reducing the transmission time without augmenting the transmission bandwidth fits very well for overcoming the drawbacks of the optical channel, which heavily depend on atmospheric conditions such as clouds [6]. By doing so, the link layer may adjust the transmission time of the frames without reducing the number of symbols to transmit according to weather forecasts [20].…”

Time-Packing as Enabler of Optical Feeder Link Adaptation in High Throughput Satellite Systems

“…By doing so, the minimum Euclidean distance between received constellation points did not change, enabling a higher data rate without augmenting the communication bandwidth. With the implementation of timepacking, the use of high-order modulations could be avoided; therefore, this signaling is specially appealing for satellite systems with optical feeder link, as the Peak-to-Average Power Ratio (PAPR) of the transmit signal does not grow notably, and thus the power of the non-linear distortion and the signaldependent noise that are added can be kept low [8], [9].…”

Linear Time-Packing Detectors for Optical Feeder Link in High Throughput Satellite Systems

“…More precisely, it was shown that in presence of a binary sequence of Sincpulses, a 25%-data-rate-increase was feasible by shrinking the time between adjacent Sinc-pulses to about 80.2% of the Nyquist symbol time. Unfortunately, in order to capitalize this gain, the complexity of the detector must grow notably when the roll-off factor of the Sinc-pulses decreases, the overlapping factor between adjacent Sinc-pulses grows, and/or the order of the modulation scheme augments [5], [6]. For this reason, it is necessary to study the performance of low-complexity linear detectors, as the performance of Maximum-Likelihood Sequence Estimation (MLSE) impairs notably when the number of trellis states in the Viterbi algorithm is limited [7].…”