Summary: Abstract - 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.