Parameter Modeling for Small-Scale Mobility in Indoor THz Communication

Abstract

Despite such challenges as high path loss and equipment cost, THz communication is becoming one of the potentially viable means through which ultra-high data rate can be achieved. To compensate for the high path loss, we present parameter modeling for indoor THz communication. To maximize efficient and opportunistic use of resources, we analyze the potential workarounds for a single access point to satisfy most of the mobile terminals by varying such parameters as humidity, distance, frequency windows, beamwidths, antenna placement, and user mobility type. One promising parameter is antenna beamwidth, where narrower beams results in higher antenna gain. However, this can lead to "beamwidth dilemma" scenario, where narrower beamwidth can result in significant outages due to device mobility and orientation. In this paper, we address this challenge by presenting a mobility model that performs an extensive analysis of different human mobility scenarios, where each scenario has different data rate demands and movement patterns. We observe that for mobile users, there are optimal beamwidths that are affected by the mobility type (high mobility, constrained mobility, and low mobility) and AP placement.

An Overview of Signal Processing Techniques for Terahertz Communications

“…In THz indoor NLoS scenarios, the total received signal is mainly accumulated from diffuse reflections [142]. Smallscale mobility in indoor THz scenarios is also studied in [143] as a function of several variables, such as frequency windows, beamwidths, distance, humidity, mobility type, and antenna placement. It is observed that there exist optimal beamwidths for specific mobility types and AP placement strategies.…”

“…In such scenarios, multiuser interference is unavoidable. In particular, in [143], the opportunistic use of resources under mobility is maximized to satisfy the constraints on humidity, distance, frequency bands, beamwidths, and antenna placement. Furthermore, a stochastic model of multi-user interference is proposed in [178], alongside modulation schemes that minimize the probability of collisions.…”

Ultra-dense low data rate (UDLD) communication in the THz

“…For example, a user/robot can have a phone, smartwatch, smart photonic wrist bands, VR glasses, smart clothes, implanted medical devices, and multiple other sensors. This explosion of indoor devices coupled with random small-scale mobility of the user [7] can overwhelm the indoor Figure 1: Minimum antenna beamwidth (in degree) required in the THz band to achieve a channel capacity of 10 bps/Hz for static users at 60% relative humidity and varying distances.…”

“…Densification of devices will not only overwhelm the system, but also can act as blockages for the THz signals. Besides high mobility and frequent change in device orientation, i.e., small-scale mobility [7], will lead to outages and lower coverage. However, with opportunistic use of the THz band, scheduling, and efficient resource allocation, multiple use-cases requiring a low data rate for indoor devices can be satisfied [11].…”

“…To compensate for the losses, devices will need higher antenna gain or narrower antenna beamwidth. Using the antenna gain analysis for static users proposed in [7], shows that even with the narrowest pencil-beams, there are distance and operating frequency limitations, which makes the THz very sensitive to usecases, shown in Fig. 1.…”