Real-time voice communication over the internet using packet path diversity

Abstract

The quality of real-time voice communication over besteffort networks is mainly determined by the delay and loss characteristics observed along the network path. Excessive playout buffering at the receiver is prohibitive and significantly delayed packets have to be discarded and considered as late loss. We propose to improve the tradeoff among delay, late loss rate, and speech quality using multi-stream transmission of real-time voice over the Internet, where multiple redundant descriptions of the voice stream are sent over independent network paths. Scheduling the playout of the received voice packets is based on a novel multi-stream adaptive playout scheduling technique that uses a Lagrangian cost function to trade delay versus loss. Experiments over the Internet suggest largely uncorrelated packet erasure and delay jitter characteristics for different network paths which leads to a noticeable path diversity gain. We observe significant reductions in mean end-to-end latency and loss rates as well as improved speech quality when compared to FEC protected single-path transmission at the same data rate. In addition to our Internet measurements, we analyze the performance of the proposed multi-path voice communication scheme using the ns network simulator for different network topologies, including shared network links. KeywordsPacket path diversity, multi-stream transmission, multi-path transmission, adaptive playout scheduling, multiple description coding, forward error correction, voice over IP.

Picture-perfect streaming over the Internet: is there hope?

“…For instance, [10,9] proposes a scheme for real-time audio transmission using multiple independent paths between a single sender and a single receiver, where multiple description coding (MDC) is used in multi-path delivery and a FEC approach is used in single-path delivery. In contrast, we believe that it is important to understand the effects of multi-path delivery on loss characteristics, even without the use of coding techniques -an advantage being that it can then be made to work well with any coding technique or media codecs.…”

VoIP Aggregation in Wireless Backhaul Networks

“…It is a natural expectation that the wireless backhauls should provide similar or better performance for most existing Internet applications, including real-time applications like VoIP, which has been identified as one of the most important real-time applications with potential commercial interest [7][8][9][10][11]. However, supporting VoIP applications over wireless backhaul networks poses a number of new challenges that have not existed in the previous Internet VoIP research [12][13][14].…”

Network-Adaptive Video Communication Using Packet Path Diversity and Rate-Distortion Optimized Reference Picture Selection

“…To maximize the benefits of diversity in media communication, multiple streams can be sent, in a distributed manner, over independent or largely uncorrelated network paths with diversified loss and delay characteristics [1][2][3][4][5][6][7][8][9]. In this way, the probability of a negative disturbance, such as packet loss, impacting all channels at the same time will be small.…”

“…As discussed in [1], IPv4 source routing is usually turned off within the Internet for security reasons. More promising is to implement path diversity by means of an overlay network that consists of relay nodes [1,2,13], where packets are sent along different routes as being encapsulated into IP packets that have the addresses of different relay nodes as their destination. At the relay nodes, packets are forwarded to other relay nodes such that the packets from different description streams travel along as few common links as possible.…”