S. Rein, F.H.P. Fitzek (Germany), and M. Reisslein (USA)
Internet Protocol, Mean Opinion Score, Mobile Multime dia, Robust Header Compression, Voice Quality
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 evalu ate the transmission of Global System Mobile telecommu nications (GSM) encoded voice with ROHC over a wire less link. We evaluate the bandwidth savings and the voice qualities using a wide array of objective voice quality met rics 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 transmis sions in half. In addition, our extensive voice quality evalu ations indicate that ROHC improves the voice quality com pared 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 prob ability of to 0.36 for an error probability of on the 5-point Mean Opinion Score.
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