Bidirectional Packet Aggregation and Coding for Efficient VoIP Transmission in Wireless Multi-Hop Networks

Jun HASEGAWA  Hiroyuki YOMO  Yoshihisa KONDO  Peter DAVIS  Katsumi SAKAKIBARA  Ryu MIURA  Sadao OBANA  

IEICE TRANSACTIONS on Communications   Vol.E92-B   No.10   pp.3060-3070
Publication Date: 2009/10/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E92.B.3060
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Advanced Information and Communication Technologies and Services in Conjunction with Main Topics of APCC/COIN 2008)
wireless ad-hoc network,  packet aggregation,  network coding,  VoIP,  

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This paper proposes bidirectional packet aggregation and coding (BiPAC), a packet mixing technique which jointly applies packet aggregation and network coding in order to increase the number of supportable VoIP sessions in wireless multi-hop mesh networks. BiPAC applies network coding for aggregated VoIP packets by exploiting bidirectional nature of VoIP sessions, and largely reduces the required protocol overhead for transmitting short VoIP packets. We design BiPAC and related protocols so that the operations of aggregation and coding are well-integrated while satisfying the required quality of service by VoIP transmission, such as delay and packet loss rate. Our computer simulation results show that BiPAC can increase the number of supportable VoIP sessions maximum by around 87% as compared with the case when the packet aggregation alone is used, and 600% in comparison to the transmission without aggregation/coding. We also implement BiPAC in a wireless testbed, and run experiments in an actual indoor environment. Our experimental results show that BiPAC is a practical and efficient forwarding method, which can be implemented into the current mesh hardware and network stack.