New approaches to clipped OFDM channels: modeling and receiver design

We present a vector-based approach to modeling an orthogonal frequency division multiplexing (OFDM) system with intentional clipping and oversampling at the transmitter. We show how to model the clipping noise as a function of the transmitted signal. We also show that a clipped OFDM channel can be considered to be similar to a MIMO channel, with the addition of a clipping indicator vector which indicates which samples are clipped. This approach allows many existing equalization and detection techniques to be implemented. We then present an iterative MMSE receiver based on this model, and show that it outperforms existing techniques. We also present maximum-likelihood estimation of the clipping indicator vector. We show how to apply coding to this vector to improve performance, a technique we call coded-clipping.