The Bridge - Issue 3, 2021 - 28

Feature
Facilitating Satellite-Airborne-Balloon-Terrestrial
Integration for Dynamic and Infrastructure-less Networks
respect and ensure that the consumed energy is less
than the stored energy in the previous time slot.
B. Back-hauling Optimization
In this section, we propose integrating GBSs and TBs
with HAPs using hybrid FSO/RF links. A key challenge
for networking under partial or no infrastructure is
establishing reliable back-hauling links to the TBs or
gateways involved in the provisioning of connectivity
services for ground users. The back-hauling
optimization problem is proposed to optimally find
back-hauling associations, HAP locations, transmit
powers, and FSO alignment between transceivers
to maximize user back-hauling throughput while
respecting resource limitations. This involves utilizing
high-frequency directional bands, such as optical bands,
as much as possible to minimize the interference
between transceivers. It is assumed that each HAP
is strictly associated to one back-hauling station (i.e.,
either a gateway station or satellite station). Additionally,
we assume a limited number of HAPs associated
with the same back-hauling station. For the FSO link
between different transceivers, we assume that the
alignment angle can be optimized to achieve LoS
alignment. In this case, we propose FSO link discovery
and establishment. One way is to explore out-ofband
techniques where support from an RF or GPS
is available to exchange the angle/direction and also
exchange information about how they are oriented.
In addition to the HAP back-hauling, back-hauling links
between GBSs and TBs with HAPs can be established
based on the form of communications. (i) For uplink,
Table I: Simulation parameters
Sub-area A
Sub-area (Km × Km)
Dimensions (Km)
Users distribution (%)
Number of TBSs
Example
THE BRIDGE
70 × 70
[x:55-125],
[y:0-70]
40
30
City area
Sub-area B
70 × 70
[x:55-125],
[y:110-180]
30
After disaster area
Sub-area C
Remaining
Remaining
30
Rural area
two possible links can be established: GBS to HAPs or
TBs to HAPs.(ii) For downlink, two possible links can
be established: HAP GBSs or HAPs to TBs, as shown
in the solid lines in Figure 2. Therefore, another binary
decision variable must be introduced for the backhauling
associations.
V. RESULTS AND DISCUSSION
This section provides some numerical results to
outline the benefits of using our proposed integration
to improve global connectivity. The numerical results
setup is within an area of 180km x 180km. We
distribute U ground users in this area in three different
sub-areas: (i) sub-area A of 70km x 70km, (ii) sub-area
B of 70km x 70 km, and (iii) sub-area C, the remaining
area. We also consider different users' density
distributions in each sub-area, as shown in Figure 3.
Sub-area A contains 30 GBSs with x and y ranges
as (x:55-125km) and (y: 0-70 km), respectively.
It contains 40% of total number of ground users.
Subarea B has no GBSs with x and y ranges as (x:55-
125km) and (y:110-180km), respectively. It contains
30% of total number of ground users. Sub-area C is
the remaining area. Further, the total number of TBs
and HAPs used are 30 and 8, respectively, as given in
Table I.
We study the enhancement of the achievable downlink
and uplink throughput when HAPs and TBs assist the
terrestrial network. We also consider different backhauling
bandwidth cases to represent both RF-only and
hybrid FSO/RF scenarios to investigate the limitation of
the RF-only scenario.
https://hkn.ieee.org/
The Bridge - Issue 3, 2021

Table of Contents for the Digital Edition of The Bridge - Issue 3, 2021
