Channel Measurements and Modeling for Low Terahertz Communications in an Aircraft Cabin

Abstract

The low terahertz band (0.1 THz -1 THz) offers very high data rates for novel mobile applications and constitutes a promising candidate to meet the requirements in aviation, enabling future wireless in-flight entertainment systems. An extensive knowledge of the propagation effects in the radio channel in complex scenarios is a prerequisite to successfully design a communication system. This paper presents a measurement campaign in a real aircraft investigating the radio channel at 300 GHz for different deployments of a wireless inflight entertainment system. The propagation effects as well as temporal and spatial channel characteristics are analyzed for likely communication links between an access point and a user equipment. In the same way, interference links between two user equipments are studied, reporting transmission and reflection losses for various components of the aircraft. A deterministic and geometry-based channel model is derived and extended to cover the effect of human blockage that suggests an integration of the access point into the passenger service unit. The measurement and realistic path loss models can be used in further link-and system level simulations and contribute to the design of future in-flight entertainment systems.

THz Measurements, Antennas, and Simulations: From the Past to the Future

“…In the past years, various CBCS systems have become available [25], [26], [27], [28] allowing either dynamic measurements or reducing the measurement time in static environments significantly. CBCS have been widely used for measurements in various environments such as outdoor environments [27], office environments [26], industrial environments [29], data centers [30], trains [31], automotive [32], and aircrafts [33]. Recently, CBCS have also been used for channel characterisation with regard to the determination of key performance indicator (KPI) for physical layer security such as secrecy capacity [34], [35].…”

“…Measurements reported both in indoor [36], [23], [33], [29], and outdoor [40], [41] environments have shown that THz communications works also in non-line-of-sight (NLoS) situations by exploiting single or even multiple reflection or scattering processes, yielding a reduction of the received power level of compared to line-of-sight (LoS) as low as a few dB. Generally speaking, the pathloss coefficients for NLoS are in a similar range as those at cm-wave frequencies; however, shadowing is more severe, raising the probability of outage.…”

“…In highly reflective environments [23], [24], [33], the delay spread can be considerable -the order of multiple inverse bandwidths -despite the use of directional antennas. Again, this holds true for both indoor and outdoor environments.…”

“…Aligning the measurement setup with the applicationoriented use case, the measurement results are valuable in three different ways: First, various channel parameters are calculated and the propagation is characterized [33]. Second, the measurement data is used for calibration or validation of propagation simulations [31].…”

Eavesdropping Measurements for Applications in Office Environments at Low THz Frequencies

“…Measuring also relative values, the channel sounder has to be calibrated with respect to the amplitude and to the delay of the CIR with a back-to-back (B2B) calibration. By measuring the amplitude and the delay of known waveguides, a correction term can be calculated following the procedures described in [22] and [23], respectively. However, due to IQ-imbalances, the measurements are affected by an inaccuracy of up to ±2 dB but the calibration of the imbalances is an ongoing topic [24].…”