Linear versus channel coding trade-offs in full diversity full rate MIMO systems

The use of multiple transmit (TX) and receive (RX) antennas allows to transmit multiple signal streams in parallel and hence to increase communication capacity. We have previously introduced simple convolutive linear precoding schemes that spread transmitted symbols in time and space, involving spatial spreading, delay diversity and possibly temporal spreading. Such linear precoding allows to attain full diversity without loss in ergodic capacity. Linear precoding however cannot provide coding gain. Hence practical transmission systems have to involve channel coding. Threading is an example of a MIMO transmission system in which spatial diversity gets exploited via channel coding only. Practical symbol constellations however only allow the exploitation of a limited diversity order by the channel coding. Hence powerful yet simple MIMO TX schemes can be obtained by combining the coding gain and diversity exploitation of classical channel codes with linear precoding to exploit the remaining diversity degrees. A typical design would use channel coding to exploit temporal fading with linear precoding to exploit spatiofrequential fading.