Abstract: A data transmission method includes receiving, by an optical line terminal (OLT) from an optical network unit (ONU), uplink burst data that includes a synchronization data block and a payload, where the synchronization data block includes first synchronization data, wherein the first synchronization data includes a first preamble and an ONU identifier, and a first bandwidth occupied by the first frequency distribution of the first synchronization data is narrower than a second bandwidth occupied by the second frequency distribution of the payload, and obtaining, by the OLT from the first synchronization data, the ONU identifier.

Abstract: A charging station monitoring system including: a sensing device, a digital camera and a communication device which are arranged at a charging apparatus of a charging station, the sensing device and the digital camera each having a sensing range covering a parking lot associated with the charging apparatus and an area around the parking lot; a controller configured to determine an occupation state of the parking lot and/or detect and record an action of a third party or foreign object based on sensed information from the sensing device and the digital camera; and a charging assistance device configured to recommend an environmentally friendly charging station if an energy storage device of the electric vehicle has not been fully charged and needs to be further charged.

Abstract: A multiplexing device for orthogonal frequency division multiplexing (OFDM) system comprises a first unit for combining N-path differential-modulation symbol sequences and mapping to sub-carriers of inverse fast Fourier transformation, N is an integer which is greater than 1, and a second unit for executing the IFFT of sub-carriers to realize frequency division multiplexing of multi-path differential-modulation symbol sequences. The multiplexing transmitting device can not only realize multiplexing transmission of multi-path signals in differential OFDM system, but also the device can be very simply realized, the multiplexing method for OFDM system is also disclosed.