Digital DS-CDMA receivers working below the chip rate

We consider the problem of designing low-complexity digital receivers for CDMA systems operating over channels with single or multiple propagation paths. We extend some of our recent sampling results for certain classes of non-bandlimited signals and develop a method that takes advantage of transform techniques to perform channel estimation and signal detection from a low-dimensional subspace of a received signal, that is, by sampling below the traditional Nyquist rate. By lowering the sampling rate we can reduce computational requirements compared to existing solutions, allow for slower A/D converters and significantly reduce the power consumption of digital receivers. In effect, we use an algorithmic solution to improve hardware specifications in terms of complexity and power.