Corrupted encoded data detection for a CELP decoder

Abstract

Undetectable data corruption in wireless communication links can occur in some cases, including cases in which a ciphering algorithm can fail to generate the same keystream for encryption at a receiver side as it does for a sender side. In wireless speech communication, such corruption might trigger an explosion of decoded sound, which might in turn hurt a user's ear. This article presents a simple algorithm for detecting corruption for a typical code-excited linear-prediction (CELP) speech decoder. The algorithm requires no additional bits for corruption detection, but detects it by monitoring the amplitude ratio of decoded adaptive and fixed excitation signals in CELP. Its practicality is demonstrated by simulation.