A network layer approach to enable TCP over multiple interfaces
Wireless Networks
A hybrid approach for authenticating MPEG-2 streaming data
MCAM'07 Proceedings of the 2007 international conference on Multimedia content analysis and mining
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A variety of wireless interfaces are available for today's mobile user to access Internet content. When coverage areas of these different technologies overlap, a terminal equipped with multiple interfaces can use them simultaneously to improve the performance of its applications. We term the services enabled by such simultaneous use of multiple interfaces as Multi-Access Services. These services constitute Bandwidth Aggregation, Mobility/Reliability Support, Resource Sharing and Data-Control Plane Separation. As a first step towards realizing in practice the above mentioned services, we develop a network layer architecture that introduces minimal changes to the infrastructure. We also identify and implement on an experimental testbed, the various functional components that make up this architecture. While the architecture can support many different services, we explore in depth one such service provided by the architecture: Bandwidth Aggregation (BAG) in the context of Video and TCP applications. For video applications, an important aspect of the architecture when providing BAG services is the scheduling algorithm that partitions the traffic onto different interfaces. We propose one such algorithm Earliest Delivery Path First (EDPF), that ensures packets meet their playback deadlines by scheduling packets based on the estimated delivery time of the packets. We show through analysis, implementation and simulations that EDPF performs close to an idealized Aggregated Single Link (ASL) discipline and outperforms by a large margin other scheduling approaches based on weighted round robin. Apart from the scheduling algorithm, we also consider a content adaptation algorithm, Min Cost Drop (MC-DROP) to selectively drop video frames when adequate bandwidth cannot be reserved on the interfaces. While BAG services can improve the throughput of TCP applications, it introduces challenges in the form of packet reordering. So, we propose Packet Pair based Earliest-Delivery-Path-First for TCP (PET) scheduling algorithm that minimizes reordering by sending packet pairs on the path that introduces the least amount of delay. A Buffer Management Policy (BMP) is also introduced at the client to hide any residual reordering from the TCP receiver. We show through simulations that PET in combination with BMP achieves good bandwidth aggregation under a variety of network conditions.