Some 5G communication services have been launched and are expected to usher in a new era of next-generation communication. On the other hand, because this communication is found in environments with LTE, Wi-Fi, and other existing communication systems, more complex noise issues are foreseen. Before 5G devices fully enter communication environments, we studied the noise environments for 5G communication and examined the noise suppression measures that will be needed.
5G communication environments are expected to be used alone in few actual cases. Instead, typically, they are expected to be added to existing communication environments. In these environments, the spurious emissions generated inside devices due to existing wireless communication can connect to 5G wireless circuits and result in communication interference.
We are finally at a state where actual 5G devices have started to appear, but because it takes time to evaluate using actual devices, we envisioned a system where a millimeter wave circuit like that shown in the figure was added to a 5G communication circuit. We then used frequency multiplier and mixer test boards installed in the circuit to evaluate the effect when external noise connects to a signal line required for operation. In this study, spurious emissions are defined as excess signals other than the communication signals themselves, and they include communication signals from other communication and high-order harmonics.