A Preliminary Investigation of Concatenated Coding Schemes Utilizing Soft Decision Processing.

Several preliminary investigations into various concatenated coding schemes were performed. All concatenated schemes passed symbol reliability information from the inner decoder to the outer decoder. All analyses were performed using computer simulation of the communication links. Explicit implementation of digital functions and detailed models of analog functions of the receiver terminal were included in the link simulations. The propagation disturbances were modeled using the multiple phase screen MPS propagation simulation. Several concatenated codes were analyzed and their performance was compared to standard convolutional codes using Viterbi soft decision decoding. Advantages and disadvantages of the various error correction schemes were discussed. Issues relating to quantization effects were given particular attention. An advanced concatenated codingdecoding structure with apparent promise was developed, but has not yet been studied in detail.