METHOD AND APPARATUS FOR DETECTING BAD DATA PACKETS RECEIVED BY A MOBILE TELEPHONE USING DECODED SPEECH PARAMETERS

摘要

The mobile telephone detects bad data packets by decoding speech parameters represented by the packets and comparing those speech parameters against acceptable ranges of speech parameters. If the speech parameters do not lie within the acceptable ranges, the packets are discarded. This speech parameter-based detection of bad data packets is particularly useful in mobile telephones receiving variable rate data packets wherein an error in determining the rate of a packet results in the entire packet being decoded at an incorrect rate, thereby likely causing an annoying audible artifact in the decoded speech signal. Such rate detection errors can occur eventhough a CRC or other conventional error detection check fails to detect the bad packet. In an exemplary implementation, receiver (132) of mobile telephone (128) receives signals encoded with TIA/EIA/IS-95-A standards. Variable rate decoder (140) determines linear speech parameter frequencies and codebook gain parameters using linear predictive coding techniques. The parameters are tested against acceptable ranges to detect bad data packets by speech parameter examining unit (144).