The proliferation of wireless technologies and inexpensive network-cameras has enabled low-cost and quick deployment of cameras for several surveillance applications, such as traffic monitoring and border control. Smart Camera Networks (SCNs) are networks of cameras that self configure and adapt to improve their operation and reduce the demand on human operators. However, SCNs are constrained by the ability of the underlying wireless network. Streaming video over a network requires substantial bandwidth, and strict Quality-of-Service (QoS) guarantees. In contrast, existing wireless networks have limited bandwidth, and the protocols do not guarantee QoS. Thus, for SCNs to scale beyond a small number of cameras, it is vital to design efficient video delivery protocols that are aware of the limitations of the underlying wireless network.

We propose to use Video Aggregation, a technique that enables efficient delivery of video in SCNs by combining related video streams. Existing SCNs use traditional routing protocols where intermediate network routers simply forward the video packets from cameras towards the video analysis center (or base-station). This is inefficient in SCNs since multiple cameras often cover overlapping regions of interest, and video information of these regions are redundantly transmitted over the network. The proposed video aggregation protocol eliminates redundant transmissions by dynamically pruning the overlapping areas at the intermediate routers. The routers blend the received streams into one panoramic video stream with no overlaps. Aggregation also dynamically controls the streaming rate to avoid network congestion and packet drops; the routers adjust the rate of the outgoing video by estimating the available network bandwidth. Thus, base-stations receive video frames with minimal packet drops, thus improving the quality of received video.

Our testbed and simulation results show that aggregation outperforms traditional routing both in terms of received video quality and network bandwidth usage. Our testbed experiments show that aggregation improves the received video quality (the Peak Signal-to-Noise-Ratio metric) by 54%. In larger networks, we observed that aggregation eliminates up to 90% of packet drops that were observed in SCNs with traditional routing. In future, we plan to develop a suite of video delivery protocols, which include SCN-aware scheduling and transport protocols.


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