Page 154 - ITU Journal Future and evolving technologies – Volume 2 (2021), Issue 2

ITU Journal on Future and Evolving Technologies, Volume 2 (2021), Issue 2

UAV1
UAV2

Flight path
of the target

Fig. 1 – Laser mesh created by two airborne UAVs that are quasi‑static. A uniformly spaced laser array is considered on each airborne UAV. The laser
array platform is tilted at each airborne UAV. The coverage area and shape of the elements of the mesh can be changed by changing the spacing between
the individual laser beams and changing the position of airborne UAVs or changing the tilt of the array platform.

In this paper, a new alternative to radar systems for • The energy emissions from the radar can be detected

the detection, classi ication, localization, and tracking of from a long distance, hence, exposes them to the risk

aerial objects is provided. In our work, a novel concept of detection. However, in the proposed approach,
of the mesh of laser beams in the sky is proposed. A sim‑ there are no long‑range emissions sourced from the
ple illustration of the concept using two UAVs is shown in transmitter (TX) or the RX.
Fig. 1. The laser mesh forms a web‑like structure in the

• Radar systems use complex algorithms for clutter re‑

sky. Laser beams in the mesh can be transmitted either
jection. These algorithms have limitations depend‑

from a satellite or a High‑Altitude Platform (HAP) such
ing on the size and height of the lying target, the mo‑

as hot air balloons, medium altitude rotary‑wing UAVs,

tion of the objects in the surroundings, and the ter‑

or both. The transmitted laser beams can be received ei‑
rain type. In the proposed approach, no clutter re‑

ther directly on the ground or rotary‑wing UAVs near the
jection is required.
ground. Any lying object that crosses the laser mesh will

• The radar systems depend on the delay of the re‑

block the path of the laser beams and will be detected
ceived pulses to range a target and pulse repetition
and subsequently localized. Laser mesh steering is intro‑

frequency needs to be correctly selected to avoid

duced to steer virtual gates at different azimuth positions.

range ambiguity. In our approach, a target is de‑

The laser steering in the azimuth plane helps in localiza‑
tected instantaneously without delay and range am‑
tion, classi ication, and tracking of moving aerial objects,
biguity issue.
and increases the coverage area. A mathematical model

of the blockage of the laser beam of the Gaussian pro ile is • Large and bulky antennas are required for long‑

provided. Moreover, Gaussian training data that has the range transmission and reception of radar signals.

features of 3D shape, maximum velocity, pitch and drift There are additional maintenance overheads for ro‑
angles, and a maximum altitude is used for model devel‑ tating radars. On the other hand, laser beam gener‑

opment. A data set is created for eleven different type of ation, and reception are performed using electronic
lying objects grouped in four categories. The results ob‑ and optical equipment that are concise and more ef i‑

tained from simulations proves the viability of our pro‑ cient compared to mechanically controlled radar sys‑
posed approach. tems.

The main advantages of our proposed approach com‑

pared to radar systems are summarized as follows: • Complex sounding signals and processing tech‑

niques are used for the detection, localization, and

ication of sophisticated targets e.g., terrain

• Our proposed approach is energy ef icient compared hugging drones and missiles. Our proposed ap‑

to the radar systems. The radar systems broadcast

proach does not require complex sounding signals

the radio signals in the free space and the transmit‑ and associated processing techniques.
ted energy spreads in different directions. A small

fraction of the transmitted energy from the radar is • The probability of detection of different types of
received back. On the other hand, in our approach, a aerial targets with the proposed approach is signif‑
point‑to‑point connection is established without sig‑ icantly higher compared to conventional radar sys‑
ni icant spreading of the transmitted energy towards tems. The probability of false alarms using our ap‑

the receiver (RX). Moreover, the received laser en‑ proach is also small compared to radar systems as

ergy can be recycled into other forms. the detection is solely dependent on the interruption
of the laser link.
140 © International Telecommunication Union, 2021