This paper analyzes the bit error rate (BER) performance of cooperative communication using relays which is capable of efficiently combating wireless impairments and hence will extend the coverage. With the requirement of higher data rate, the distortion of the received signal caused by multipath fading channel becomes a major problem. The relay assisted multiple input and multiple output (MIMO) Multi carrier code division multiple access (MC-CDMA) system can tackle the problem and provide higher data rate for future wireless communication system. But inter symbol interference (ISI) caused by the frequency selectivity of the channel affect the overall performance. To improve the performance of the system further, it is proposed to incorporate channel estimation based equalization and relaying in MIMO MC-CDMA system. The simulation results show performance can be still with higher number of sub carriers (SCs) and antenna configuration.

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The quality of a wireless link can be described by three basic parameters, namely transmission rate, transmission range and transmission reliability. With the advent of multipleinput multiple-output (MIMO) assisted Multicarrier code division multiple access (MC-CDMA) systems, the abovementioned three parameters may be simultaneously improved. The MC-CDMA combined with the MIMO technique, has become a core technology for future mobile radio communication system. However, possible potential gain in spectral efficiency is challenged by the receiver's ability to accurately detect the symbol due to inter symbol interference (ISI). Multipath propagation, mobility of transmitter, receiver and local scattering cause the signal to be spread in frequency, different arrival time and angle, which results in ISI in the received signal. This will affect overall system performance. The use of MC-CDMA mitigates the problem of time dispersion. However, still it is necessary to remove the amplitude and phase shift caused by channel. To solve this problem, a multiple antenna array can be used at the receiver, not only for spectral efficiency or gain enhancement, but also for interference suppression. This can be done by the beam forming, efficient channel estimation with strong equalization. This paper proposes MIMO MC-CDMA system with beamforming, Minimum mean square error (MMSE) equalization with ideal channel estimation. The simulation result shows improved BER performance when the sub carrier (SC) and antenna configuration was increased.

An accurate localization technique is considered as the significant entity in Vehicular Ad hoc Networks (VANETs) for facilitating emergency message data transmission in diversified critical safety applications. In VANETs, the system of global positioing is generally used for estimating the position of the vehicles in the network for attaining neighborhood awareness in the event of warning message dissemination. However, the existence of green foliages, buildings, indoor parking lots and urban streen canyons introduces NLOS situation that introduces unwanted errors that crumbles the degree of data dissemination in emergency situations. In this paper, Spotted Hyena and Simulated Annealing Optimization Algorithm (SHSAOA)-based positioning scheme was proposed for precise estimation of NLOS nodes. İt included the advantages of improved simulated annealing (SA) integrated into SHOA for establishing better balance between the process of exploitation and exploration in the search space. This positioning approach generated candidate solutions by deriving the merits of the trajectory-based charateristics of SA throughout the algorithmic development process in order to improve the local optimization process. This proposed SHSAOA utilized the distance infotmation that are associated with the vehicle trajectory, number of vehicles and error in distance information for assessing the precise location of the NLOS nodes in the network. The simulation results of the proposed SHSAOA scheme confirmed minimized localization error with maximized accuracy in transmission, warning message transmission rate, channel utilization degree and neighborhood awareness degree with different vehicular density and NLOS nodes.