Voice Quality Evaluation for Wireless Transmission with ROHC

Robust Header Compression (ROHC) has recently been proposed to reduce the large protocol header overhead when transmitting voice and other continous media over RTP/UDP/IP in wireless networks. In this paper we evaluate the transmission of Global System Mobile telecommunications (GSM) encoded voice with ROHC over a wireless link. We evaluate the bandwidth savings and the voice qualities using a wide array of objective voice quality metrics including SNR metrics, spectral distance metrics, as well as parametric distance metrics. We find that for a wide range of loss probabilities on the wireless link, ROHC roughly cuts the bandwidth required for voice transmissions in half. In addition, our extensive voice quality evaluations indicate that ROHC improves the voice quality compared to transmissions without ROHC, especially for large bit error probabilities on the wireless link. The improvment increases exponentially from about 0.075 for an error probability of to 0.36 for an error probability of on the 5-point Mean Opinion Score.