Simplified Molecular Absorption Loss Model for 275-400 Gigahertz Frequency Band

Abstract

This paper focuses on giving a simplified molecular absorption loss model for a 275-400 GHz frequency band, which has significant potential for variety of future short and medium range communications. The band offers large theoretical data rates with reasonable path loss to theoretically allow even up to kilometer long link distances when sufficiently high gain antennas are used. The molecular absorption loss in the band requires a large number of parameters from spectroscopic databases, and, thus, the exact modeling of its propagation characteristics is demanding. In this paper, we provide a simple, yet accurate absorption model, which can be utilized to predict the absorption loss at the above frequency band. The model is valid at a regular atmospheric pressure, it depends on the distance, the relative humidity, and the frequency. The existing simplified model by ITU does not cover frequencies above 350 GHz and has more complexity than our proposed model. The molecular absorption loss increases exponentially with the distance, decreasing the utilizable bandwidth in the vicinity of the absorption lines. We provide a model to approximate the window widths at the above frequency band. This model depends on the distance, the relative humidity, the frequency, and the maximum tolerable loss. It is shown to be very accurate below one kilometer link distances.

Performance Analysis of THz Wireless Systems in the Presence of Antenna Misalignment and Phase Noise

“…h f respectively model the deterministic path gain, the misalignment fading and the stochastic path gain. The deterministic path gain coefficient can be expressed as h l = h f l h al , where h f l models the propagation gain according to the Friis equation, while h al stands for the molecular absorption gain and can be evaluated as in [5]. For the pointing errors, the probability density function (PDF) of the channel coefficient, h p , can be obtained as in [2].…”

Analytical Performance Evaluation of THz Wireless Fiber Extenders

“…Next, by substituting (14) into (10), the ergodic capacity can be expressed as (15) or, by using [28, eq. (15.1.1)], as…”

“…In more detail, in [14], the authors presented a novel propagation model for THz nano-scale communications. Additionally, in [15], a simplified path-loss model for the 275 − 400 GHz band was introduced. Furthermore, in [16], a multi-ray THz propagation model was presented, while, in [17], a propagation model for intrabody nano-scale communications was provided.…”

Error Analysis of Mixed THz-RF Wireless Systems

“…Scanning the technical literature, a great amount of research effort has been put on modeling and evaluating the performance of both THz [4]- [11] and RF wireless systems (see e.g., [12] and references therein). In particular, in [4], the authors reported a novel THz-band propagation model, whereas, in [5], a simplified molecular absorption loss model was delivered. The latter model was used in [6] for the quantification of the THz link capacity.…”