“…Instead, a few studies have been concentrated on its FEC mechanism, as will be seen in Section 4.2. Barberis et al [2001], Huang et al [2007], and Moura et al [2007] used a hypothetical VBR codec in their simulated mechanisms for adaptive rate control, which consisted of a collection of CBR sources with bitrate values ranging from 8 to 64 kb/s in steps of 8 kb/s. Finally, Abreu-Sernandez and Garcia-Mateo [2000] proposed, to the best of our knowledge, the only study that uses VBR control in an actual VoIP system, implemented on the Motorola DSP96002, with bitrates of 9.4, 7.7, and 5.9 kb/s.…”