New Properties of Convolutional Codes and Some Applications to Communication Systems

Convolutional codes are used extensively for error correcting purposes in digital data communication systems. This paper identifies a class of codes which possess a `trellis path uniqueness' (TPU) property. The encoders of these codes (which we refer to as TPU codes) possess a stronger one-to-oneness property than that identified by Massey & Sain or McEliece. Furthermore, TPU codes are shown to possess a predictive property. Certain communication systems require predictions from received data (e.g. for fading envelope prediction, equalization or for window-edge correction schemes). It is shown that TPU codes provides this capability without requiring any extra redundancy. In addition to the predictive property, this paper highlights the possibility of exploiting the TPU property directly for synchronizing Viterbi decoders and for path-metric weighting.