Evaluation of VoIP in a Mobile Environment using an end-to-end Handoff Mechanism

In parallel with the growth of VoIP services, a large number of manufacturers have begun to develop multimode devices capable of connecting to multiple wireless access networks simultaneously. These multimode terminals have, in principle, the capability to support seamless handover between different radio access networks. One handover solution that utilises the IP diversity which these multimode devices can deliver is SIGMA. SIGMA is a promising end-to-end transport layer handover solution based on SCTP. The objective of this paper is to investigate if SIGMA is capable of providing seamless handover of VoIP calls without degradation in voice quality. To achieve this, we developed a Linux based testbed on which we implemented a VoIP client and server using SIGMA handoff. Each voice call uses the G.711 voice codec over RTP. PR-SCTP is used in place of the traditional UDP as the transport layer protocol. SIGMA based handover was used during full duplex voice calls between the client and server. The ITU-T E-Model has been used to calculate the voice quality during the handover. Results show that SIGMA can be used as a seamless handover mechanism for VoIP without any impact on voice quality.