Performance comparison of antenna diversity and slow frequency hopping for the TDMA portable radio channel

The authors compare the performance of a TDMA (time-division multiple-access) system plan using two-branch antenna diversity to other TDMA system plans using channel and time slot interleaving and slow frequency hopping/burst error correction (SFH/BC). Results indicate that the system designer can trade off spectral efficiency by using a double-error-correction code with channel interleaving and SFH to make the SFH/BC system perform as well as a system using two-branch antenna diversity. For a system with interleaving and SFH, the number of hopping frequencies required depends on the code used and on the design of the demodulator (i.e. hard versus soft decisions). As long as the code is chosen such that the system can handle the complete failure of one of the hopping frequencies, it can achieve about the same outage probability or speech block dropping rate as a system using antenna diversity. However, this equality is exacted at the price of spectral efficiency. In this instance, the decrease in required signal-to-interference ratio (S/I) is not enough to offset the decrease in the number of available channel sets caused by the wider bandwidth required to transmit the lower rate code. Other coding plans must be evaluated for relative spectral efficiency