Page 282 - Kaleidoscope Academic Conference Proceedings 2024

2024 ITU Kaleidoscope Academic Conference

12
14 RIS -NOMA
AF Relay NOMA RIS-NOMA
12 10 8 AF Relay NOMA
Throughput (Mbps) 8 6 Sum Rate (Mbps) 6
10

4 4
2
2
0 0
5 10 15 20 25 30 0 5 10 15 20 25 30
Transmit Power (dB) SNR(dB)

Figure 4- Throughput versus Transmit power Figure 5- Throughput versus Transmit power
The resultant SINR can be expressed using the modelling interference and improve the total signal strength that is
discussed in [18] and can be written as received at the destination. However, The AF relay is a more
straightforward method in which the relay amplifies and
 1 h h P transmits the signal that has been received without any
sR
 = 1 1 R d (13) external processing and hence lags at high SNR.
(  2 h 2 + 1  2 h h / h 2 )  2
+
1
1 R d
1 R d
2 R d
2 1 R
1
R
To facilitate spatial multiplexing, RIS regulates the spatial
distribution of reflected signals by serving multiple users
The achievable rate and the throughput can be calculated simultaneously, thus, it has the potential to enhance the
using the equation 6. system's capacity and throughput and this can be seen from
the plot shown in the Fig. 4. Additionally, by generating a
3. SIMULATION RESULTS variety of propagation paths, reducing fading, and enhancing
overall system reliability, the RIS can offer high spatial
In order to validate the closed form expressions obtained in diversity as compared to the AF relay. The AF relay has
the proposed work presented in section II, systematic monte limited scope for beamforming capabilities as compared to
Carlo simulation has been performed for both the STAR-RIS RIS and hence low throughput as compared to the RIS.
NOMAV2V as well as for the AF relay-based NOMA V2V
models. Thorough investigation was carried out for accuracy Fig. 5 illustrates the sum rate plot for RIS and AF relay, The
of the benchmark performances of both the model and a results of the simulation indicate that under all conditions,
comparative study was carried out for the maximum the sum rate of the signal monotonically increase when the
achievable rate and throughput of the both models. The maximum transmit power threshold of rises and when the

entire model was simulated for 2 vehicular models, the transmit power threshold of rises, the power assigned to

distance between the vehicles and RIS and Vehicle to relay vehicles increases, resulting in a higher achievable rate that
were all kept at 100 m. the model was validated for Rayleigh the user demands. In order to send the signal point to point,
channel for urban scenario and the channel gain was taken to a specific vehicle, the SDR algorithm modulates the
the random value between zero and one. The power reflection phase shift of each reflecting unit on the RIS by
transmitted by both the relays have been assumed to be same enhancing the maximum transmit power threshold

and was taken as 1W, the number of RIS element was taken simultaneously optimizing the phase shift of reflected signal
as 81, noise power was taken as -80dBm in all the cases. which substantially increases the vehicles signal rate.
First and the foremost, In the Fig. 3, maximum achievable In the proposed comparison of both methods, STAR-RIS
rate of the two models has been compared with respect to the V2V NOMA has outperformed AF relay V2V NOMA.
SNR, It can be noticed that at low SNR values the achievable However, the AF relay has better scope, it does not require
rate of RIS assisted model and AF relay assisted model both accurate channel state information (CSI) for beamforming or
have comparable values but as the SNR increases beyond 15 reflection corrections, it works better in situations where it is
dB the AF relay assisted model lags the RIS assisted model difficult to get CSI quickly and accurately. Since AF relay
and this is possible because the reconfigurable elements are does not depend on exact placement or reflection
introduced by STAR-RIS, which have the ability to reflect modifications, it may be more adaptable in scenarios where
and change the incident signals simultaneously. By it is difficult to determine the relay's exact location.
implementing intelligent adjustments to the phase shifts of
these elements, RIS is able to generate constructive

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