A high performance diversity selection technique for TDMA portable radio communications

The authors describe and show performance results for a diversity-selection technique in a frequency-selective fading portable radio channel. Diversity selection is performed by using a quality measure obtained from the demodulation process. This technique is compared to diversity selection based on power and diversity selection after channel decoding. It is found that this diversity selection technique is more effective in mitigating selective fading than a conventional technique based on power and that it performs almost as well as diversity selection after channel decoding. This diversity selection technique can be implemented at the portable handset by using only one receiver if the base station transmits in at least one time slot in addition to the communication slot. Thus, its use does not significantly increase the portable´s hardware complexity. Simulations and experiments have confirmed that two-branch diversity using the proposed method can provide reliable speech communications using TDMA (time division multiple access) for a portable radio channel with RMS spread of 555 ns or less and a transmission rate of 450 kb/s