Many researches in the world deal with driving on the road to ensure optimum safety. In this context, several telecommunication technologies are often used to connect the vehicles via continuous wireless communication with the infrastructure, exchange data and information relevant to increase overall road safety and enable cooperative traffic management. These systems are not reliable for all situations and the difficulties encountered by the drivers. We have been proposed the Multi-band Orthogonal Frequency- Division Multiplexing system based on Ultra Wide Band (MB-OFDM UWB) as a good candidate to insure a Vehicle to Infrastructure (V2I) communication with high data rate and good performances in terms of Bit Error Rate (BER). However, Inter-Carrier Interference (ICI) resulting from Doppler shift phenomenon degrades MB-OFDM UWB system performance and raises a significant challenge in wireless mobile environment. In this study, V2I communication based on the MB-OFDM UWB technology is studied and analyzed for 200 Mbit/s, over multipath channel using the IEEE802.15.4a channel model with Doppler shift for different speeds. The theoretical formulas of BER in Additive White Gaussian Noise (AWGN) and Rayleigh channels are calculated and are compared to the simulation results in MB-OFDM UWB system. The comparison shows that simulation results are consistent with theoretical formulas. The degradation in the performance of the proposed system solution becomes worse with a high speed 250 Km h-1, so itâs necessary to use new receiver solutions. The Extended Kalman Filer (EKF) and the Maximum Likelihood (ML) estimation with ZF equalizer have been proposed and have been compared to Zero-Forcing (ZF) in order to combat the ICI effect. For high value of speed (250 Km h-1), the EKF method performs better than the ML method, better than the ZF equalizer and offers much improvement in performance in term of BER
The exponential chip weighting waveforms have been designed with the purpose of multiple access interferences (MAI) rejection based on the concept that the optimum despreading sequence in reference emphasizes the transitions in the received spreading signal of interest. The despreading sequence weighted by exponential chip waveforms was determined by only one parameter. The objective of this study, was to introduce neural networks (NN) to facilitate the computing of the bit error rate (BER) performance of a direct sequence code division multiple access (DS/CDMA) system over a Rayleigh multipath fading with power control error, for both coherent and noncoherent receivers, by producing the despreading sequences weighted (WDS) by exponential chip weighting waveforms. Numerical results show that the parameter values of the exponential chip weighting waveforms produced by the proposed network are nearly optimal and satisfactory in viewpoint of the achieved bit error rate (BER) performance
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