LSB-coded modulation and its applications to microwave digital radios

We present a forward error correction (FEC) scheme, called LSB-coded modulation. The scheme combines coding and modulation based on the observation that the symbol errors mostly occur due to the mix-up of adjacent ones. It is simple to implement, efficient and flexible with different data and coding rates. It is particularly suited for high speed, bandwidth-efficient digital communication systems. We have developed practical implementation techniques, such as FEC frame synchronization and receiver carrier phase ambiguity resolution. This scheme has been successfully applied to Harris 155.52 Mbps, 128QAM 30 MHz bandwidth, SONET/SDH microwave digital radios.