Amalgamated Generalized Low Density Parity Check and Luby Transform Codes for the Wireless Internet

Luby transform codes (LT) were originally designed for the binary erasure channel (BEC) encountered owing to randomly dropped packets in the statistical multiplexing aided Internet, where transmitted packets are not affected by the fading or noise of the environment. For the sake of transmitting data over the BEC routinely encountered in statistical multiplexing aided wireless Internet-style scenarios, LT codes have to be combined with classic channel codes. In this paper we introduce a novel almagamated LT coding and generalized low density parity check (G-LDPC) coding scheme. Upon exploiting the packet erasure information provided by the G-LDPC decoder for the LT decoder, the proposed scheme achieves a low bit error ratio (BER) for packet error ratio (PER) E_b/N₀ values in excess of 3.2 dB when transmitting data over the AWGN-BEC channel having a packet erasure probability of P_e=0.1. When communicating over the Rayleigh-BEC channel at P_e=0.1, an E_b/N₀ value of 5.3 dB was required. In comparison to the serially concatenated LT-GLDPC scheme using no information exchange between the G-LDPC decoder and the LT decoder, the amalgamated LT-GLDPC arrangement achieved an E_b/N₀ gain of up to 1.6-2.5 dB.