Green Communication Systems in IOT-Enabled Smart Cities via Wavefront Multiplexing Schemes

Many cities are adapting to new technology and advanced communication networks to update and improve infrastructure, such as public utilities, transportation, and other services. A green communication scheme using an orthogonal wavefront (WF) multiplexing scheme spatially combined with orthogonal frequency-division Multiple Access (OFDMA) techniques forms a spatial WF OFDMA transceiver. This WF OFDMA transceiver is proposed for smart city applications, including both fixed and mobile internet of things (IOT). The WF multiplexing and de- multiplexing technique serves as the preprocessing and postprocessing method of the transceiver. With coordinated multiple point forward transmission, this system establishes a communication network which can be applied to multiple access points (APs) with down links to a single mobile unit (MU) or multiple MUs either in mobile or stationary environment. These MUs can be IOT based mobile shopping systems, smart mobile services, mobile traffic controls, etc.}{Although signals received are non-coherently due to different distances between APs and MUs in a city, they can be compensated and coherently combined via adaptive equalizers at MUs periodically in a mobile environment. This is achieved by using pilot signals with an optimization method at the MU. Moreover, the required effective equivalent isotropically radiated power (EIRP) from APs to the MUs is significantly reduced due to multiple non-coherent transmission. Accordingly, the interference to adjacent frequency bands’ signals will be low. This green communication network can also be applied to the MUs staying in a stationary environment with initial setting only on fixed equalizers at MUs.