Robust slope region for wideband CDMA with multiple antennas

We analyze a low power, wideband CDMA system with multiple antennas. The joint "slope region" - of transmission rates at minimum energy per bit s derived as a function of proportion between vanishing rates for multiple users. Vertices of the slope region may be achieved by a matched filter linear interface, followed by successive interference cancellation. We introduce and evaluate the "robust slope region", the largest region which is inside every other slope region and is therefore independent of the relative proportion between transmission rates. Furthermore, we find the "robust slope", the maximum slope which can always be guaranteed to all users.