Tracking and diversity for a mobile communications base station array antenna

A simulation model for analyzing the performance of antenna arrays in a mobile flat-fading environment is derived and applied to particular problems of tracking, combining and angle diversity. The model introduces angular coordinates that allows for the flexibility of utilizing directional co-channel interferers as well as providing the flexibility to test various array adaptation algorithms in a two dimensional mobile environment. The model is applied to a base-station 7 element half-wavelength spacing antenna array, operating at a carrier frequency of 815 MHz. The angle diversity performance is investigated by observing the bit error rate (BER) improvement for a π/4 DQPSK operating at 10 Kb/s. A tracking algorithm is demonstrated for maintaining the directional beam on the mobile for various vehicle trajectories and velocities up to 80 km/hr. The diversity and tracking algorithms performed well in the real environment as was predicted by simulation. Angle diversity provided a factor of 2 improvement in the BER, for a π/4 DQPSK signal at an Eb/No of 31 dB