Implementation of adaptive modulation on the Sunrise software radio

In this paper, we investigate the implementation issues associated with adaptive modulation using pilot symbol assisted modulation based channel estimators for Rayleigh fading environments. The scheme will be implemented on the BAE System´s Sunrise receiver (which has TI´s C67 DSP). Sunrise has a download capability enhanced by the WJ-8629A developer´s kit, which provides the end user the capability to create algorithms capable of addressing evolving requirements related to receiver filtering, demodulation, decoding and analysis. Modulation is adapted on the basis of the channel SNR estimated from the received signal. Three sets of switching levels for modulation schemes were assumed and correspond to SNR at which QPSK, 16QAM, 64 QAM achieve ∼0.1%, 1% and 10% BER in a Gaussian channel. We also investigate the impact of channel estimators, channel quality estimation and the effect of frame delays on adaptive modulation.