New piggybacking algorithm in VoIP using enhanced G.722.2 codec with larger frames

In this paper, we present the design of a new piggybacking algorithm for VoIP implemented using the G.722.2 codec. In piggybacking, multiple speech frames that include those transmitted in the past are encapsulated in a single packet. Because redundant copies of each frame are transmitted to the receiver, the receiver can recover those lost frames when one or more packets are lost or arrive late in their transmission. In this paper, we have enhanced the G.722.2 codec by removing further redundancies in the multiple frames encapsulated in piggybacking and by having only one set of LP coefficients for all the subframes encapsulated. We create multiple versions of the codec, each using a different frame size. Our new codec can encode the multiple frames with little degradation in PESQ, while having substantial bit savings. Its performance is evaluated against the original method of piggybacking over random losses, as well as that using packet traces collected in the PlanetLab.