Apparatus for transmitting a symbol via a unipolar signal, the apparatus comprising: a symbol allocating unit configured to receive a symbol as a bipolar signal and allocate the symbol to one or more signals among a plurality of signals comprising first and second signals, wherein the symbol allocating unit comprises: a polarity detector configured to allocate the symbol either to the first signal or to both the first and second signals by determining a polarity of the symbol, allocating the symbol to the first signal only in response to a determination that the symbol has a first polarity, and allocating the symbol to both the first and second signals in response to a determination that the symbol has an opposite polarity to the first polarity, and a polarity mapper configured to invert a polarity of a negative symbol before pulse shaping is applied; a filter bank comprising a plurality of orthogonal pulse shaping filters each configured to apply pulse shaping to a respective one of the plurality of signals and output a filtered signal, wherein the filtered signals outputted by the plurality of pulse shaping filters are orthogonal signals; and a transmitter configured to transmit the sum of the filtered signals as a unipolar signal, wherein the transmitted signal is a weighted sum of the orthogonal pulse shapes, wherein the plurality of orthogonal pulse shaping filters comprises a first pulse shaping filter configured to apply a unipolar first pulse shape and a second pulse shaping filter configured to apply a bipolar second pulse shape, the bipolar second pulse shape being orthogonal to the unipolar first pulse shape, and wherein a sum of the first pulse shape and the second pulse shape is unipolar. a symbol allocating unit configured to receive a symbol as a bipolar signal and allocate the symbol to one or more signals among a plurality of signals comprising first and second signals, wherein the symbol allocating unit comprises: a polarity detector configured to allocate the symbol either to the first signal or to both the first and second signals by determining a polarity of the symbol, allocating the symbol to the first signal only in response to a determination that the symbol has a first polarity, and allocating the symbol to both the first and second signals in response to a determination that the symbol has an opposite polarity to the first polarity, and a polarity mapper configured to invert a polarity of a negative symbol before pulse shaping is applied; a polarity detector configured to allocate the symbol either to the first signal or to both the first and second signals by determining a polarity of the symbol, allocating the symbol to the first signal only in response to a determination that the symbol has a first polarity, and allocating the symbol to both the first and second signals in response to a determination that the symbol has an opposite polarity to the first polarity, and a polarity mapper configured to invert a polarity of a negative symbol before pulse shaping is applied; a filter bank comprising a plurality of orthogonal pulse shaping filters each configured to apply pulse shaping to a respective one of the plurality of signals and output a filtered signal, wherein the filtered signals outputted by the plurality of pulse shaping filters are orthogonal signals; and a transmitter configured to transmit the sum of the filtered signals as a unipolar signal, wherein the transmitted signal is a weighted sum of the orthogonal pulse shapes, wherein the plurality of orthogonal pulse shaping filters comprises a first pulse shaping filter configured to apply a unipolar first pulse shape and a second pulse shaping filter configured to apply a bipolar second pulse shape, the bipolar second pulse shape being orthogonal to the unipolar first pulse shape, and wherein a sum of the first pulse shape and the second pulse shape is unipolar.