Spectral efficiency of JD-CDMA mobile radio systems applying coherent receiver antenna diversity with directional antennas

At present, antenna diversity concepts based on directional antennas are subject to worldwide research activities. These concepts are promising to enhance the performance of future mobile radio systems. Especially, mobile radio system concepts using antenna diversity with directional antennas at the base stations are expected to increase the admissible number of users and to decrease both the cluster size and the transmission power, respectively. This paper intends to quantify the possible performance enhancement with respect to spectral efficiency as a performance measure for mobile radio systems. In order to obtain quantitative results, a method to determine said spectral efficiency is proposed and applied in directional inhomogeneous mobile radio scenarios. For different antenna configurations, the spectral efficiency in the uplink of a joint detection CDMA mobile radio system-being a promising candidate for third generation mobile radio systems-is evaluated. Due to the exploitation of the directional inhomogeneity of mobile radio channels by the application of antenna diversity with directional antennas, the spectral efficiency is found to be considerably larger as compared to concepts using a single omnidirectional antenna