An analysis of the effective performance of a handset diversity antenna-proposal for the diversity antenna gain based on a signal bit-error rate

In the present cellular radio system in Japan (PDC), diversity reception techniques are employed for mobile terminals. To discuss the optimum structure of the diversity antenna, one important consideration involves the transmission quality prescribed in the system design, which is the average bit-error rate (BER) in a digital system, produced by the antenna correlation and effective gain characteristics. However, there is no "figure-of-merit" to estimate the performance of the diversity antenna from the viewpoint of the system criterion, thus it is difficult to know how effectively the diversity antenna functions in a practical use situation. In this paper, an analysis of the effective performance of a handset diversity antenna has been done by introducing a new "figure-of-merit", named the diversity antenna gain (DAG), based on the signal bit-error rate. By using the DAG, the diversity gain and the antenna effective gain in a multipath environment can be estimated at the same time. Evaluating the DAG for the /spl pi//4-shift QPSK signals, the diversity antenna for the PDC system with a post detection two-branch selection combining scheme has been analyzed. The analytical results indicate the DAG characteristics under various incident wave propagation environments with the antenna structure as parameters.