  Multiplexing services as a key communication technique to effectively combine
multiple signals into one signal and transmit over a shared medium.
Multiplexing can increase the channel capacity by requiring more resources on
the transmission medium. For instance, the space-division multiplexing
accomplished through the multiple-input multiple-output (MIMO) scheme achieves
significant capacity increase by the realized parallel channel, but it requires
expensive hardware resources. Here, we present a novel multiplexing
methodology, named meta-multiplexing, which allows ordinary modulated signals
overlap together to form a set of "artificial" parallel channels, meanwhile, it
only requires similar resources as ordinary modulation schemes. We prove the
capacity law for the meta-multiplexing system and disclose that under broad
conditions, the capacity of a single channel increases linearly with the signal
to noise ratio (SNR), which breaks the conventional logarithmic growth of the
capacity over SNR. Numerous simulation studies verify the capacity law and
demonstrate the high efficiency of meta-multiplexing. Through proof-of-concept
hardware experiments, we tested the proposed method in communication practices
and achieved a spectral efficiency of 81.7 bits/s/Hz over a single channel,
which is significantly higher than the efficiency of any existing communication
system.
