Always Best Packet Switching: The Mobile VoIP Case Study

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Currently, a mobile device equipped with multiple heterogeneous wireless Network Interface Cards (NICs) cannot take advantage of its capabilities as the conventional mobility management approach allows it to select and use only one of its NICs at a time. In contrast to this approach, this case study proposes the so-called Always Best Packet Switching (ABPS) model that allows applications to use simultaneously all the available NICs, and switch each given IP datagram through the most suitable NIC. This depends on the characteristics of the datagram itself. Specifically, it shows that the ABPS model enables mobile applications to create policies for load balancing and recovery purposes in order to support effectively mobile multimedia services. This paper also describes a cross-layer mechanism termed Robust Wireless Multi-Path Channel (RWMPC) that adopts the ABPS model in order to meet effectively interactivity and low packet loss Quality of Service (QoS) requirements of Voice over IP (VoIP) applications that run on mobile hosts equipped with multiple WLAN NICs. By exploiting RWMPC services, VoIP applications can establish and maintain separate wireless links with different access points providing access to, possibly independently managed, wireless networks, and select for each UDP datagram the best link to be used for communication purposes.