  This paper presents a new method, referred to as the cocktail
intra-symbol-code, to reveal the possibility of exceeding the channel limit of
QPSK input by transmitting independent signals in parallel manner and
separating them the receiver, repetitively. In the proposed modulation scheme,
the rhombic constellation is created to work with the modulated signal and the
channel code in Euclidean- and Hamming space cooperatively. The theoretical
derivations are done under the assumption of using the capacity-achieving codes
and the results are shown in terms of the reliable bit rates.
