The Range Increase of Adaptive versus Phased Arrays in Mobile Radio Systems.

In this memorandum we compare the increase in range with multiple-antenna base stations using adaptive array combining to that of phased array combining. With adaptive arrays, the received signals at the antennas are combined to maximize signal-to-interference-plus-noise ratio rather than only from a directed beam. Although more complex to implement, adaptive arrays have the advantage of higher diversity gain and antenna gain that is not limited by the scattering angle of the multipath at the mobile. Here, we use computer simulation to illustrate these advantages for range increase in both narrowband and spread spectrum mobile radio systems. For example, our results show that for a 3degrees scattering angle (typical in urban areas) a 100-element array base station can increase the range 2.8 and 5.5-fold with a phased array and an adaptive array, respectively. Also, for this scattering angle, the range increase of a phased array with 100 elements can be achieved by an adaptive array with only 10 elements.