Demonstration of bidirectional wireless transmission
Summary
Transmissions exceeding 100Gbps enable both optical-fibre and wireless connections for communication lines between fixed stations, facilitating the construction of flexible backhaul networks, wireless connections with mobile base stations during events, and temporary lines during disasters. In the 6G era, the demand for wireless communications will accelerate with the emergence of high-definition video transmission, autonomous driving, remote medical surgery, and advanced applications such as VR and AR, all of which increase the need for high-capacity wireless communication. NTT, DOCOMO and NEC are working to increase capacity using a novel spatial multiplexing method that uses OAM, a property of electromagnetic waves. OAM, a physical quantity that describes certain properties of electromagnetic waves, is generated by adjusting the phase difference of signals from the transmitting antenna so that the same-phase trajectory spirals in the direction of propagation. While there is a report of a successful real-time transmission test that achieved 14.7Gbps over 40 metres in a single direction using OAM-mode multiplexing technology with digital signal processing circuits in the 71GHz to 86GHz band (E-band), which is used in existing wireless systems, real-time transmission capacity needs to be further increased for 6G and beyond wireless systems.