Studies have used IsOWC interconnections as a practical way to trans
receive signals in between satellites using carrier as optical signal and
propagation medium as a space. Information can be safely transported
across the globe via IsOWC connections. The current work describes a
polarisation division multiplexed quadrature phase shift keying (PDM-
QPSK) based highest speed and longest reach IsOWC system using a
single channel. To increase receiver sensitivity, at receiver terminal
coherent detection is installed and DSP module has been implemented
to reduce losses caused by abductant atmospheric effects and to
forecast the phase (carrier). We have evaluated necessary OSNR
(optical signal to noise ratio) to obtain the appropriate BER (bit error
rate) to evaluate the output of suggested link (BER). According to the
results, a reliable 112 Gbit/s transmission with a good BER is possible
at 22,500 km. Additionally, we quantitatively examine how connections
with rising pointing faults perform in terms of OSNR. Additionally, a
comparison of the suggested link with the body of current literature
points to a better system towards (maximum data with maximum range)
and spectrum efficiency (maximum data with maximum range).
Coherent detection, DSP, and PDM-QPSK provide a strong foundation
for creating spectrally effective IsOWC connections.