An error-floor reduction technique for short-length LT codes

Luby transform (LT) codes are often employed during best-effort packet transfers to offer rateless erasure protection. Efficient as they are, these randomized codes with a small number of input symbols often post an inevitable performance trade-off between the decoding failure rates in their waterfall and error-floor regions. In order to surmount this trade-off, we propose a new encoding strategy that requires a portion of the high-degree output symbols of an LT code to abandon the conventional equally-probable input selection strategy; instead, connect themselves to some specially selected low-degree input symbols. Our simulation results show that short-length LT codes with merely 103 input symbols yield significantly lower symbol/block failure rates at a small overhead of reception as they employ the proposed strategy. These performance-enhanced rateless codes can have potential applications in real-time multimedia broadcasting.