Adaptive OFDM Modulation Used For SDR

Software defined radio (SDR) is the future trend for mobile communication. A SDR is supposed to facilitate high speed multimedia application for future mobile standards. Adaptive modulation forms an integral part of SDR system with robust and high data rate capability. Here we have analyzed adaptive modulation scheme with their performance in changing channel condition. The modulation scheme studied for adaptive modulation are BPSK, QPSK 16QAM , 32 QAM ,64 QAM . Different order modulations and different coding schemes, allow to send more bits per symbol, thus gaining higher throughputs and better spectral efficiencies. But it must also be noted that when using a modulation technique such as 64-QAM with less overhead bits, better signal-to-noise ratios (SNRs) are necessary to overcome any Intersymbol Interference (ISI) and also maintain a certain bit error ratio (BER). The use of adaptive modulation gains wireless technologies to yielding higher throughputs while also covering long distances. This paper focusing on the physical layer design (i.e. Modulation), here the various used modulation type will be implemented in a single Matlab function that can be called with the appropriate coefficients. A comparison will be made in terms of SNR and BER relation.