Unequal Error Protection of MELP Compressed Speech Based on Plotkin Type LDPC Code

An unequal error protection scheme is proposed for robust transmission of MELP compressed speech. Plotkin type constructed LDPC codes provide different protection to different part of the codeword. In our scheme, we use this code to encode MELP bit stream in accordance with the sensitivity of the bits in a frame to errors, giving more protection to the bits affecting the speech quality more. Simulation results show that the objective assessments of speech quality after transmission are greatly improved comparing with the EEP scheme under the same channel conditions.