Application of Information Theory to the Design of 4th Generation Cellular Communication Systems

The design of 4th Generation Cellular Communication Systems will face manychallenges, including the need to achieve very high spectrum efficiency whencompared to 3rd Generation cellular systems. In this paper, we investigate thefundamental limits of DSSS-CDMA versus TDMA for achieving high spectrumefficiency by presenting the capacity regions for each including the effectsof multiple transmit and receive antennas. To assess the channel capacityregion for local area and wide area coverage, a channel model based uponuncorrelated Rayleigh fading and model with a strong spatial correlation andRicean component are evaluated. For multiple transmit and receive antennas,both open loop and closed loop capacity regions are assessed, where the closedloop capacity assumes channel state information at the transmitter and optimumpower allocation. Conclusions from the work include an assessment of whatapproaches hold the best promise for achieving high spectrum efficiency forfuture cellular communication systems. This revised version was published online in August 2006 with corrections to the Cover Date.