On the Design of Pilot Symbol Assisted Codes

We propose a novel technique, hereby referred to as pilot symbol assisted coding (PSAC), where a predetermined fraction of binary pilot symbols is interspersed with the channel-coded bits at the channel coding stage, instead of multiplexing the pilots with the data symbols at the modulation stage, as in classic pilot symbol assisted modulation (PSAM). We will subsequently demonstrate that the PSAC-aided scheme succeeds in gleaning more beneficial knowledge from the inserted pilots, because the pilot bits are not only useful for estimating the channel at the receiver, but they are also beneficial in terms of significantly reducing the computational complexity of the channel decoder. Our results suggest that in the specific application example considered the PSAC-aided scheme requires up to 45% fewer message-passing updates per decoded bit than the corresponding channel coded PSAM benchmarker scheme.