  Shannon channel capacity of an additive white Gaussian noise channel is the
highest reliable transmission bit rate (RTBR) with arbitrary small error
probability. However, the authors find that the concept is correct only when
the channel input and output is treated as a single signal-stream. Hence, this
work reveals a possibility for increasing the RTBR further by transmitting two
independent signal-streams in parallel manner. The gain is obtained by
separating the two signals at the receiver without any inter-steam
interference. For doing so, we borrow the QPSK constellation to layer the two
independent signals and create the partial decoding method to work with the
signal separation from Hamming to Euclidean space. The theoretical derivations
prove that the proposed method can exceed the conventional QPSK in terms of
RTBRs.
