Effects of Post and Early Selection on SEC Based Transmit Diversity Systems with Linear Power Loading

Switch and examine combing (SEC) diversity scheme provides a lowest-complexity closed-loop transmit diversity solution. Furthermore, by probing sequentially available branches with different power loading levels, the SEC based transmit diversity systems can offer considerable amount of transmit power savings. In this paper we propose two variants for the SEC with power loading schemes proposed earlier, namely: post and early selection schemes, and we analytically evaluate their performance and complexity. It is shown that early selection scheme has the advantage of lower average transmit power by selecting the best branch with the minimal power required, and the least number of channel probes. Post selection scheme on the other hand has less average feedback load at the expense of slightly higher average transmit power.