Özet:
Releasing autonomous vehicles in the near future; communication of vehicles
with each other to circumvent traffic congestion, road safety, fuel-saving, efficient
transportation, road tolls, their connecting over the internet and storing of data of
vehicles on cloud and fog enforce research of vehicular communication systems. In the
first chapter of this dissertation, non-wide sense stationary (WSS) vehicular channels
having various issues are addressed. Then, the literature about vehicular channels are
presented.
Although shadowing effects are mostly neglected in the literature, it is known that it is
available in the most wireless communication environment. Hence, a channel model
like generalized-k (KG) including shadowing is a realistic one. Therefore, KG
fading
channels are described in the second chapter of this dissertation because the selected
channel for each different topic addressed in this dissertation is the KG
fading channel.
In wireless communication, applying diversity techniques such as
multiple-input-multiple-output (MIMO), maximum ratio combining (MRC), antenna
selection, equal gain combining (EGC), beamforming is important in order to increase
communication quality. One of them is the maximum ratio transmission (MRT)
technique with low receiver complexity can make ultra reliable vehicular feasible
in practice. In the third chapter of this dissertation, performance improvement
with MRT over KG
channels is investigated by considering error rates and outage
probability (OP).
In recent years, non-orthogonal multiple access (NOMA) has drawn a lot of attention
due to serving multiple users in the same resource blocks (i.e., the same time-slots and
frequency bands). It accomplishes that by multiplexing multiple users in the power
domain with superposition coding (SC) at the transmitter and by using successive
interference cancellation (SIC) at the receiver. Thus, it considerably reduces frequency
scarcity and latency compared to orthogonal multiple access (OMA) techniques used
in previous communication generations. Therefore, in the fourth chapter of this
dissertation, the performance of downlink-non-orthogonal multiple access (NOMA)
which provides a noticeable gain in the frequency spectrum, quite decreases latency,
and is provisioned to be used in the fifth generation, is researched in KG vehicular
fading channels.
In the fifth chapter of this dissertation, the performance of uplink-NOMA over KG
vehicular channels is studied. Frequency scarcity and latency leads inherently to a
bigger problems in vehicular channels due to the requirement of fast and reliable.
Therefore, NOMA is more important for vehicular channels than other channels. To
this end, performance metrics such as OP, average channel capacity (AVC), and symbol
error probability (SER) are mathematically analyzed for the considered system.
