Abstract:
Millimeter-wave is a promising technology for Vehicular ad-hoc Networks (VANETs). Millimeter-wave is, however, susceptible to path loss and fading, which degrades system performance. Error-free data between Vehicle to Vehicle (V2V) and Vehicle to Infrastructure (V2I) in the context of fading and mobility of vehicles calls for in-depth research.
In addition to the above-mentioned limitations, challenging issues degrading the reliability of VANET are the problems of high penetration loss and blocking. To establish effective communication in mmWave networks in context of vehicles, a detailed understanding of the VANET communication channel is necessary, which differs significantly from those explored at frequencies lower than 6 GHz. When a vehicle’s speed exceeds 50 km/h, Doppler shifts can have adverse affects on the reliability of V2V communication. The transmission becomes impossible in VANET because of the increasing mobility of the nodes.
This research presents three tractable channel models for VANET in which system performance degradation due to error is addressed. In the first model, concatenated Alamouti Space-Time Block Coding (ASTBC) and Bose–Chaudhuri–Hocqueng- -hem (BCH) coding are used. The two Bit Error Rate (BER) closed-form approximations, one for BCH in Rayleigh fading and the other for BCH with ASTBC, are obtained. SNR and code rate are included in these expressions, which can be used to create VANET systems. The findings demonstrate that the BER obtained by concatenating ASTBC and BCH is 10-5 thus outperforming the traditional BER obtained by ASTBC expression. The code rate (127,36), (127,64) and (255,251) are used to evaluate the performance of the proposed expressions.
The next step is designing a comprehensive tractable model for VANET over millimeter waves that combines Reed Solomon (RS) coding with Space-Time Block Coding (STBC). The closed-form approximations for BER of RS in the Additive White Gaussian Noise (AWGN) channel and Rayleigh fading are derived. The performance of RS closed-form expressions is compared with previous BER computation approaches. The results shows that the BER lies between 10-6 to 10-7. Furthermore, the model’s performance has been compared with the current VANET communication systems, specifically the IEEE 802.11bd and 3GPP V2X communication systems. Results are comparable with V2X NR and demonstrate that our suggested approach works better than IEEE 802.11bd. As metrics for performance, throughput, Packet Error Rate (PER), and Packet Reception Ratio (PRR) are employed. The model has also been evaluated with vehicles moving at faster velocities. Further, the simulation and numerical findings show that the AWGN approximation for STBC-RS model outperforms RS-MPSK traditional system i.e the achieving the BER of 10-7. These derived expressions can be adopted in designing various VANET architectures targeting reliability in the network. The path loss and fading are reduced since the directivity of the transmitter has increased using beamforming.
The analytical and numerical results are compared, demonstrating the accuracy of our closed-form expressions. The impact of the Doppler shift using BCH and RS coding is also analyzed in VANET communication. Since Orthogonal Frequency Division Multiplexing (OFDM), which is highly susceptible to Doppler shift, is used by the IEEE 802.11p PHY layer. It is seen that the results of the suggested model surpass those of earlier models, including 802.11p.
Considering there exhibits a strong dependence of 5G/6G communication on both the molecular composition of the medium and the transmission distance. We have simulated our two closed-form approximations of BER in the THz channel. We have conducted a detailed analysis of relative humidity dependency on code rate. Further, we have analyzed code rate relation with relative humidity. The results are analyzed at different code rates. Moreover, we have compared our results with the performance of existing ASTBC technique in THz channel. The results depict that the proposed model surpasses the behavior of the ASTBC equation in THz. The findings presented here are expected to pave the way for ultra-reliable vehicular communication networks.
