Open area 2 × 2 MIMO channel model for 2 GHz low-elevation links with diversity and capacity applications

Abstract

In civil surveillance applications, unmanned aerial vehicles (UAV) are being increasingly used in floods, fires, and law enforcement scenarios. In order to transfer large amounts of information from UAV‐mounted cameras, relays, or sensors, large bandwidths are needed in comparison to those required for remotely commanding the UAV. This demands the use of higher‐frequency bands, in all probability in the vicinity of 2 or 5 GHz. Novel hardware developments need propagation channel models for the ample range of operational scenarios envisaged, including multiple‐input, multiple‐output (MIMO) deployments. These configurations may enable a more robust transmission by increasing either the carrier‐to‐noise ratio statistics or the achievable capacity. In this paper, a 2 × 2 MIMO propagation channel model for an open‐field environment capable of synthesizing a narrowband time series at 2 GHz is described. Maximal ratio combining diversity and capacity improvements are also evaluated through synthetic series and compared with measurement results. A simple flat, open scenario was evaluated based on which other, more complex environments can be modeled.

Generalized Propagation Channel Model for 2GHz Low Elevation Links Using a Ray-tracing Method

“…Compared to the open field scenario [7] with two clear coherent contributions (direct and ground reflected rays), cluttered areas introduce more rays subject to diffraction and reflection which make up the coherent or geometry-dependent component of the proposed semi-deterministic model.…”

“…Slight modifications to the model parameter extraction procedure used for open areas in [7] were introduced with the received power, P (dBm), acquired at a sampling rate of 10 kSps. The signal was then decimated by a factor of 32 (window 1, W 1 ).…”

“…This model is composed of a deterministic part, whose structure changes with the scenarios, and a statistical part, whose structure remains the same with only the parameters being modified. Figure 6 shows the channel model's schematic diagram with greater detail of the model given in [7]. The channel model consists of…”

“…A detailed path loss analysis is performed in [4], [5] and [6]. A modeling and experimental study for the open, flat areas was presented in [7] where a 2×2 MIMO semideterministic propagation channel model for UAVs with low elevation was first described. This semi-deterministic model is an evolution of a purely stochastic one developed for deep shadow conditions [8] applying a method from a vehicle-to-vehicle MIMO propagation channel model [9].…”

“…This semi-deterministic model is an evolution of a purely stochastic one developed for deep shadow conditions [8] applying a method from a vehicle-to-vehicle MIMO propagation channel model [9]. This paper aims to generalize the semi-deterministic model, originally developed for open areas [7], for more complex, cluttered scenarios such as built-up areas or areas such as those shown in Fig. 1.…”