Fountain Codes With PAPR Constraint for Multicast Communications

The Forward Link Only (FLO) merit of fountain codes is utilized to avoid excessive retransmission requests for multicast communications. Two important and basic classes of fountain codes, Random Linear (RL) codes and Luby Transform (LT) codes, are considered in this paper as application layer Forward Error Correction (FEC) codes. High Peak-to-Average Power Ratio (PAPR) is a notorious physical layer problem in OFDM systems. We take the PAPR constraint into account in the encoding of fountain codes for OFDM multicast communications. We propose a selective mapping (SLM) technique that selects the best P candidates among the QP candidates. This SLM technique performs significant better than the conventional SLM technique that selects the best candidate among the Q candidates. Mathematical analysis and computer simulation verify the excellence of our designs.