Error analysis of MPEG-4 HVXC parameters at high frequencies
Fernando Perdigão, Rui Pedro Costa Rodrigues, António Navarro · 2005
This work deals with digital speech communications at very low bit rates, like 2 and 4 kbps, transmitted over long distance SW channels at HFs such as 20 and 30 MHz. The low bandwidth at HF, usually 3 kHz, imposes serious challenges namely in terms of speech compression algorithms and their transmission over such a hostile channel. Thus, This work evaluates the coding parameter significance of the MPEG-4 harmonic vector excitation coding (HVXC) algorithm. As typical transmission parameters at these frequencies, it was assumed 2400 symb/s, 8-QAM, 16-QAM, 32-QAM and 64-QAM. The results show that the most significant parameter is V/UV at SNR less than 6 dB and the least significant ones are the parameters related to the unvoiced frames. Therefore, any access control, unequal error protection, data partitioning and grouping strategies covering a wide range of SNRs can then be designed, based on the significance results presented in This work. We also propose a solution to increase the error resilience of MPEG-4 speech encoded signals over HF channels.