DSP Implementation of QPSK and 8-QAM Transmitter for Software Defined Radio

Future wireless communication services will require a reconfigurable transmitter capable of switching between several modulation techniques. Reconfigurability could be achieved by defining the transmitter in software. To adapt to different wireless standard, future radios have to be implemented in software. Software modem radios for 2 and 2.5 Generations have already been implemented (Jeffrey, 2002). In this paper, software defined transmitter capable of switching between Quadrature Phase Shift Keying (QPSK) and 8-Quadrature Amplitude Modulation (QAM) techniques has been implemented on a Digital Signal Processor (DSP) TMS320VC5416 platform. A single coupled standard quadrature recursive oscillator has been used in the design instead of two oscillators required for the two modulation schemes. This saves program memory. The results obtained are in accordance with the simulation and theoretical analysis