the wireless transmission unit is essential. Regarding
the protocol of wireless transmissions, various communication modules are employed for
transmission of the measured signals from the signal acquisition unit to the translation unit,
such as Bluetooth and IEEE 802.15.4 Zigbee. Bluetooth has many advantages such as sufficient
transmission rates and wide accessibility. Thus, many wireless BCI systems employ
this transmission module. Including analog front-end and digital system stage, the acquisition
unit of wireless BCI systems generally operates onboard power sources such as Li-ion,
Li-polymer, and NiMH batteries.