In this work, we propose a scheme for real-time voice transmission using multiple independent paths. Experiments over the Internet show that with this scheme, the mean end-to-end latency and loss rate can be greatly reduced, compared to using FEC protected single-stream transmission at the same payload data rate. Multiple paths provide channels with independent network behavior such as loss, delay variation, and outage period. By taking the advantage of the diversified path characteristics, packets can be used and played out from a backup channel when the default path suffers from negative disturbance. For this reason, the end-to-end delay can be reduced by taking the packet with lower delay, and late loss and burst loss can be avoided with the existence of an alternate path.
The efficiency of multi-path transmission depends on the statistical independency of the paths. It also depends on the availability of an alternative path which has a mean delay not much higher than the default path. This is not difficult to obtain in practice if the paths follow close geographical routes but are serviced by different ISPs. Simulation results also show that the path diversity gain depends on the difference in propagation delay of the multiple paths and the variance of the network delay.
Multi-path transmission over the Internet can be realized by a dedicated overlay network of relay servers or by exploiting future peer-to-peer architectures.