We focus on the problem of efficient communications over access networks with asymmetric bandwidth and capability. We propose a resource-constrained asymmetric redundancy elimination algorithm (RCARE) to leverage downlink bandwidth and receiver capability to accelerate the uplink data transfer. RCARE can be deployed on a client or a proxy. Different from existing asymmetric algorithms, RCARE uses a flexible matching mechanism to identify redundant data and allocates a small sender cache to absorb the high downlink traffic overhead. Compared to existing redundancy elimination algorithms, RCARE provides a scalable sender cache that is adaptive based on resource and performance. We evaluate RCARE with real traffic traces collected from multiple servers and a campus gateway. The trace-driven simulation results indicate that RCARE achieves higher goodput gains and reduces downlink traffic compared to existing asymmetric communication algorithms. We design an adaptation algorithm for resource-constrained senders sending multiple data streams. Our algorithm takes samples from data streams and predicts how to invest cache size on individual data streams to achieve maximal uplink goodput gain. The adaptation algorithm improves the goodput gain by up to 87% compared to the baseline. In first 10% of data streams (sorted by the optimal goodput gains), RCARE achieves up to 42% goodput gain on average.

IP multicast dictates high-end routers and incurs high administrative overhead, which prevent them from being deployed in many video streaming scenarios. In this paper, we study the problem of computing the multipath multicast routes for streaming videos in Software-Defined Networks (SDNs), which adopt less expensive switches and reduce administrative overhead for lower CAPEX/OPEX. The objectives of the considered problem are robustness, load balance, SDN compatibility, and adaptiveness. We formulate this routing problem into a mathematical optimization problem, and propose two algorithms to address this problem. We implement the proposed algorithms on a popular OpenFlow controller to demonstrate its practicality, and we conduct extensive experiments to evaluate the proposed algorithms. The experiment results clearly show the merits of our algorithms over the IP multicast, e.g., we observe: (i) frame loss rate reduction between 19% and 95%, (ii) video quality improvement between 4 dB and 15 dB, (iii) sink throughput increase between 25% and 66%, and (iv) maximal link utilization reduction between 15% and 50%. We also show the tradeoff between optimality and run time of the two proposed algorithms: one of them is more suitable for smaller and more static networks, and the other one is more suitable for larger and more dynamic networks.

We design, implement, and evaluate an H.264/SVC decoder and an HTTP video streaming client on multi-core mobile devices. The decoder employs multiple decoder threads to leverage the multi-core CPUs, and the streaming server/client support adaptive HTTP video streaming. To evaluate the decoder performance, we conduct experiments using real H.264/SVC videos on a tablet and a smart phone running Android 4.0. Our experimental results demonstrate that real-time H.264/SVC decoding is feasible on multi-core mobile devices. For example, for 960×544 videos, our decoder achieves up to 20.72 FPS (Frame-Per-Second), and for 480×272 videos, it achieves up to 42.03 FPS. We also conduct extensive HTTP video streaming experiments over live WiFi and 3G cellular networks, which show that high frame rate (up to ~42 FPS), and short initial delay (as small as ~2.5 sec) are possible. We make our testbed publicly available to the research communities.

We consider the problem of asymmetric communications, which are common in many access networks. We propose a new asymmetric communication algorithm, called CacheQuery, to leverage on the already deployed downlink bandwidth and receiver capability to accelerate the uplink data transfer from one or multiple senders to a receiver. The design of CacheQuery differs from all previous asymmetric communication algorithms in two ways: (i) CacheQuery supports more flexible matching mechanism to identify redundant packet payload and (ii) CacheQuery allocates a small sender cache to absorb the potentially high downlink traffic overhead incurred by asymmetric communications. The trace-driven simulations indicate that, compared to existing asymmetric communication algorithms, CacheQuery achieves higher uplink transfer speed, yet reduces downlink traffic overhead.