Space-Time Coded Generalized Multicarrier CDMA with Block-Spreading for Multirate Services

Relying on space-time generalized multicarrier CDMA and exploiting both transmit and receive antenna diversity, we design herein multirate transceivers which guarantee deterministic symbol recovery with multipath-diversity gains regardless of the (possibly unknown) frequency-selective FIR channels and multiuser interference. Our approach is based on a three-level design of user codes: the outer code handles multiuser interference, the middle code results in space-time diversity gains, and the inner code mitigates intersymbol interference. In a multiuser/multirate setting, the use of space-time block coding with two transmit and a single receive antenna achieves guaranteed diversity gains, whereas the use of two receive antennas could potentially double the capacity of the system (in terms of maximum number of users or achievable transmission rates). Simulations illustrate the merits of our designs.