"transmitted in parallel" is correct and usable in written English.
It is usually used to refer to the transmission of multiple bits of data via multiple channels simultaneously. For example: "The data was transmitted in parallel, so it was able to be processed quickly and efficiently."
The serial signal X with length of N was transmitted in parallel.
In SDM optical networks, optical signals are transmitted in parallel through spatial modes co-propagating in suitably designed optical fibers.
The data sequences are transmitted in parallel sub-channels obtained by partitioning the wideband transmission medium in K sub-bands.
However, the situation changes in a CB-CSMA/CA system, where several frames might be transmitted in parallel.
While in multipath routing, multiple copies of one packet are transmitted in parallel along different paths to the same destination.
Let us consider Equation (12) as a process of generating redundancy symbols sc transmitted in parallel to data symbols sd.
Hence, at each transmission attempt Na STAs should be able to transmit in parallel.
Each data symbol is transmitted simultaneously (in parallel) on different subcarriers in a way similar to an MC-CDMA system with frequency-domain spreading [26].
It is because the Stream-independent scheme not only transmits data in parallel but also transmits overheads concurrently.
The NRL AMS facility provides a further enhancement, in that this system is designed to transmit ions in parallel over a broad mass range.
In order to transmit data in parallel, a pixelated system may apply spatial orthogonal frequency division multiplexing (spatial OFDM) [11, 14, 18, 20 22], which is essentially an extension of the conventional OFDM concept [23 25] to the 2-D spatial domain.
