Turbo trellis-coded modulation with time varying mixed mapping

We describe a technique to control the trade-off between the error floor and the waterfall performance of parallel concatenated trellis-coded. modulation (PCTCM), which is also known as turbo TCM, via the choice of coded-bits-to-signal mapping for a fixed component code. We demonstrate that different choice of mapping leads to different error floor and waterfall performance. One mapping may have the lowest error floor but result in poor waterfall performance, while another mapping may achieve the opposite. We then present the time-varying mixed mapping scheme for PCTCM systems. The proposed mixed mapping scheme enables us to generate a set of turbo trellis codes from two choices of coded-bits-to-signal mapping with various waterfall performance and error floor