With the fifth generation communication system in the phase of deployment, the research community has focused its attention toward a higher frequency spectrum, data rate in terabits per second, latency lower than 1 ms, and ultrahigh reliability. Communication systems having such characteristics are expected to be rolled out in the sixth generation. This article presents key technology enablers for deployment in ultra-reliable and low-latency communications for 6G networks. In addition, the potential issues related to system security and spectrum management in 6G networks are also discussed. The significant technological enablers include machine learning, channel estimation, intelligent reflecting surfaces, terahertz communication, spectrum sharing, and system security, which possess the potential to revolutionaize the future of wireless communication networks.

Visible Light Communication (VLC) is a novel optical wireless communication technology which uses Light Emitting Diodes (LEDs) and Photodiodes for coherent detection and very-high-data rate data communication system. The stringent Line of Sight (LoS) requirement in VLC makes it very suitable for Indoor Positioning System (IPS), to be used for autonomous and smart city infrastructure. The current work aims to implement a real time IPS system using VLC link in Network Simulator (NS-3). The VLC module is implemented by modelling real-time attributes of LEDs, optical channel, and the photodiodes. The localization is carried out using trilateration schemes which measures the Received Signal Strength Indication (RSSI) and the Time Difference of Arrival (TDoA) for position estimation of the target. The project is further extended to obtain a comparative analysis between VLC link and other existing technology, Wi-Fi, as far as positioning accuracy and other important performance metrics are concerned. The simulation results show significant improvement for the VLC link over the Wi-Fi link specially for the TDoA scheme accompanied by increasing number of beacon nodes.

The non-orthogonal multiple access (NOMA) technique is a strong candidate for 5G cellular networks that enable greater multiuser capacity and user fairness through multiplexing in the power domain. The user data are pulse-shaped using the orthogonal frequency-division multiplexing (OFDM) technique based on the fast Fourier transform (FFT) for conventional NOMA. We propose a discrete wavelet transform-based pulse shaping technique for NOMA. We present a closed-form expression of the bit error rate (BER) for FFT-NOMA as well as wavelet-based NOMA (WNOMA) systems. The theoretical and simulation BER results show that WNOMA outperforms FFT-NOMA in additive white Gaussian noise.

The hybrid power line communication (PLC) and visible light communication (VLC) systems can be effectively utilized for the efficient design of 5G communication setup. However, each of these integrated communication media is not primarily meant for the specific purpose of data communication, as PLC and VLC have historically served to transfer electrical energy transfer and light, respectively. With the advent of high flickering rate light emitting diodes and efficient multiplexing/modulation schemes, both technologies are observed as potential data communication carriers. Therefore, this paper presents a novel approach for modifying the modulation technique in accordance with the channel requirements of a hybrid PLC-VLC-based 5G communication systems. We provide a thorough analysis of the research work done to co-use these two technologies for data communication, suggest some exciting applications of integrated PLC-VLC systems and propose discrete wavelet transform (DWT)-based orthogonal frequency division multiplexing (OFDM) to tune the physical parameters as per the hybrid channel characteristics. Theoretical and simulation bit-error-rate results exhibit that DWT-OFDM outperforms an OFDM-based PLC-VLC system. The proposed hybrid system can be used to design smart buildings where indoor/intra-building connectivity is maintained by VLC whereas inter-building networking based on PLC communication.