# Efficient and Robust Image Communication Techniques for 5G Applications in Smart Cities
## 2 Related Work  
In the preliminary work, the evaluation of three types of diversity combining schemes has been presented. The analysis has been carried out by pre-detection and post-detection merits and demerits [3]. The diversity technique based on maximal ratio combining exhibits an enhancement in signal-to-noise ratio over fading channels compared to the single branch receiving system. Direct relationship between performance improvement and the number of diversity branches combined was presented in literature [4]. The maximum output selection scheme performed better than maximum SNR regarding BER for M-ary modulation schemes over Rayleigh channel [5]. The utilization of spatial diversity provides a noteworthy enhancement in the system capacity over flay-Rayleigh and frequency selective channels with optimum combining/equalization being employed [6]. The influence of fading on the BER can be reduced by employing the diversity reception. The performance enhancement was reported for both correlated and non-correlated fading channels [7]. The comparison between optimum combining (OC) and MRC was presented for two co-channel interferers and a random number of interferers, respectively. The Monte Carlo simulation was used to assess the system behavior by BER [8]. The closed form BER performance analysis has been presented for the equal-gain combiner with 2 or 3 branches over Rayleigh fading channel [9]. The analysis of OC and MRC showed that the channel correlation of the interfering signal did not affect the BER performance, whereas the BER performance got severely affected once the channel correlation of the anticipated signal approaching unity [10]. The study of MRC for wireless communication showed that the SNR is varying by the cross correlation between the channel vectors [11]. The use of hybrid transmit diversity was also being demonstrated by employing the selection diversity and maximal ratio combining jointly. The hybrid combination offered an improved BER performance in comparison to maximal ratio combining working alone [12; 13; 14; 15; 16; 17; 18]. The performance examination for multiple input multiple output (MIMO) MRC is demonstrated over the rician fading channel. On studying the result, it was very much evident from the simulation results that the behavior of single input multiple output (SISO) systems was equivalent to multiple input single output (MISO) system provide that the total antenna elements are fixed [19]. The BER of MRC and EGC was analyzed over gamma fading channels by considering the independent gamma fading on the diversity branches [20]. DCT offers an efficient alternative to DFT for the implementation of multicarrier transceivers. It can eliminate the ICI and ISI at a lower complexity without any guard interval [21]. The overall system performance of MRC with arbitrary fading parameters was analyzed over the flat-Nakagami-m fading channel [22]. The BER investigation for the DCT OFDM system and carrier frequency offset (CFO) on AWGN channel has been presented. The simulation analysis undoubtedly illustrates that the BER characterization of DCT-OFDM is reliable than the BER characterization of DFT-OFDM [23; 24]. The OFDM system based on the DCT outclasses the DFT-OFDM system by providing enhanced BER performance over the multipath fading channel having time-varying characteristics. The enhancement was nearly 5.5 dB regarding the signal-to-noise ratio [25]. The OFDM system based on DFT, DCT, and discrete wavelet transform (DWT) has been analyzed over AWGN channel with BPSK and QPSK are the modulation schemes being used. The BER analysis showed that DWT-OFDM outperforms the DFT-OFDM and DCT-OFDM. Additionally, the DCT-OFDM still provides better BER characterization in contrast to DFT-OFDM [26]. The analysis of MIMO systems by BER characterization was presented for OC and MRC in the existence of co-channel interference. The modulation scheme used for the study of system characterization is quadrature amplitude modulation (QAM) [27].