The Bridge - Issue 3, 2021 - 24

Feature
Facilitating Satellite-Airborne-Balloon-Terrestrial
Integration for Dynamic and Infrastructure-less Networks
and power unavailability. For this reason, one of the
proposed ideas is to integrate the GBSs with satellite
stations to improve the total network's capacity and
coverage. Satellite stations can use multiple spot
beams associated with multiple label switching
protocols and spectrum access control [1]. Therefore,
satellite stations can communicate with users with the
help of GBSs working as relays [1]. In this case, GBSs
are used to amplify the communication links between
multiple satellite stations and multiple ground users
[2]. However, because the satellite stations depend on
the terrestrial network to broadcast their signals, this
presents another limitation, especially in remote areas
and during periods of congestion or network failure.
High-altitude platforms (HAPs) and tethered balloons
(TBs) can bridge this gap and provide downlink and
uplink services in remote and congested areas. One of
the most important elements in the sixth-generation
(6G) network is that coverage must be large enough
to provide acceptable data- communication services
wherever users live, including urban and remote areas.
However, 6G networks are not intended to provide
equally good service to all areas but rather maintain
resource balance [3]. Because of the huge growth
in mobile and wireless device usage and immense
data traffic, traditional GBSs are expected to face
some difficulties in supporting the demands of users
in urban areas. This problem can be exacerbated
by failures in the ground infrastructure. However,
developing a terrestrial infrastructure that provides
telecommunication services to remote areas is hardly
feasible. To overcome these challenges, integrating the
GBSs with higher altitude stations can be a promising
solution for reaching global connectivity.
The integration of GBSs, balloons, airborne, and satellite
stations into a single wireless network can enhance
the overall network throughput. Further, the integration
of the four stations would provide reliable, seamless
throughput anywhere on Earth. This includes remote,
ocean, and mountain areas where the use of optical
fiber is limited and costly. Indeed, nowadays only
half the world's population has access to the Internet
according to recent statistics, and this unconnected
population is mostly in the poorest areas of the world
where infrastructure is scarce.
HAPs and TBs can work as aerial relay stations to
enhance the wireless channel quality between ground
THE BRIDGE
users and satellite stations. Thus, they can enhance
overall network throughput and help global connectivity
with or without the existence of a terrestrial network [4].
The altitude ranges of aerial relay stations are chosen
carefully not only to reduce energy consumption, but
also to maintain the position stability of HAPs and
TBs [5]. This solution can provide immediate wireless
connectivity to (i) ground users in remote areas
with challenged networks, (ii) on-demand users in
congested urban areas with capacity shortages due
to peak traffic, such as Olympic games, marathons, or
base-station failures, (iii) first responders and victims
in emergency or disaster-recovery situations where
infrastructure networks are unavailable or disrupted, (iv)
ground military in hostile environments, and (v) borderpatrol
services for patrolling in difficult terrain. The
main advantages of deploying HAPs over GBSs can be
summarized as [4,5]:
* High coverage range: The GBSs' broadband coverage
range is usually much less than the HAPs' range due
to high non-line-of-sight (non-LoS) pathloss.
* Dynamic and quick deployment: HAPs have the
flexibility of flying to remote or challenging areas to
provide on-demand Internet services.
* Low consumed energy: Because HAPs can be
equipped with solar power panels, where the energy
can be harvested during the daytime, then HAPs
can be self- powered with careful trajectory
optimization [6].
In turn, the main advantages of HAPs over satellite
stations can be summarized as [5]:
* Quick and low-cost deployment: HAPs can be
deployed quickly to accommodate traffic/temporal
demand, emergency, or disaster-relief applications.
One HAP is sufficient to restart the broadband
communications services by flying to desired areas in
a short, timely manner. Furthermore, the deployment
cost of satellite station is much more than HAPs'
deployment cost.
* Low propagation delays and strong signals: HAPs
can provide broadband Internet services to ground
users with less delay than satellite station. This is
due to the lower path loss attenuation compared to
satellite stations.
Several papers have investigated the HAPs' deployment
methods [6,7]. The authors in [7] studied the
deployment of the HAPs taking into account the
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The Bridge - Issue 3, 2021

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