On the spectral efficiency of CDMA with space-time spreading

We consider a general, synchronous, randomly-spread code-division multiple-access transmission scheme in which the transmitted data is any linear combination of the data and the spreading sequences are not tied to any specific transmit antenna. For large user populations, we characterize the spectral efficiency (capacity per chip) as a function of the array size, signal-to-noise ratio and the number of users per chip in the presence of frequency flat fading.