Patent ID: 6633840
Filing Date: 2003-10-14
Classification: H04L,H04W

Abstract:
A method of transmitting digital data between two telecommunication terminals on a speech channel, in particular a mobile telephone channel, via a telecommunication network comprising speech signal transcoders, the speech signals exchanged between said terminals being encoded and decoded in each terminal in accordance with a predetermined speech encoding scheme having a speech transmission format, wherein K-bit binary streams represent speech information over predetermined intervals, comprising:identifying bit configurations of said K-bit binary streams that are compatible with the transcoders (TRAU) of the telecommunication network, each of said identified bit configurations including at most Kâˆ’L bits having values dependent on content of said digital data; transcoding the digital data into transcoded data with the speech transmission format using only said identified bit configurations, the transcoded data comprising K-bit words in which (Kâˆ’L) bits have values dependent on the content of the digital data, and the remaining L bits have values independent of the content of the digital data, where both K and L are integers, K is greater than L, and L is greater than zero; transmitting the transcoded data over said telecommunications network; and decoding the transmitted transcoded data at the receiver, wherein said identifying the bit configurations of said binary streams that are compatible with the transcoders of the telecommunication network includes application of at least one of the following steps: excluding bits of the speech transmission format which are not protected by an error correcting code when transmitted as being used for said (Kâˆ’L) bits having values dependent on the content of said digital data; excluding high variations in amplitude of pitch or energy values between successive K-bit binary streams; and excluding least significant bits of parameters within the speech transmission format as being used for said (Kâˆ’L) bits having values dependent on the content of said digital data.