Concatenated Codes for Aeronautical Telemetry Kanagaraj Damodaran, Erik Perrins [esp@eecs.ku.edu]

1. In the modern world of communication systems, channel coding has become an indispensable tool to satisfy power and bandwidth constraints. As made clear by Shannon, large coding gains can be obtained by encoding large blocks of information sequences. However spectrum being a limited resource, encoding and spectral efficiency prove to be conflicting requirements which represent a basic communications problem. Concatenated Codes for Aeronautical TelemetryKanagaraj Damodaran, Erik Perrins [esp@eecs.ku.edu] Motivation Proposed Solution • High rate concatenated codes improves spectral efficiency. • Concatenated Codes • Serial concatenation of codes proved to be better in performance than parallel concatenation. • In the above technique we concatenate an outer non-recursive encoder separated from an inner (CPM)modulator (which is viewed as a code) by an interleaver. • Continuous Phase Modulation (CPM) is a constant envelope, power and bandwidth efficient digital modulation technique. Iterative Decoding BER Performance • As a common folk theorem states “All codes are good, except those that we know how to decode”. • We use a novel, low-complexity, sub-optimum iterative decoding algorithm. • The crux of the iterative decoding algorithm is a soft-input soft-output (SISO) a posteriori probability (APP) section. • rate ½ concatenated codes with CPM provides approximately a gain of 2.5 dB over conventional codes.