Measurement study on wireless camera networks

Transporting camera surveillance data using wireless networks has benefits of reduced cost and increased flexibility. In this paper, we report a measurement study of wireless camera networks using IEEE 802.11 standards, which are pervasively adopted and supported by a large number of vendors. We studied two testbeds deployed in real-world environments, one in a residential house and the other in an office building. We configured these testbeds with both one-hop star and multi-hop mesh topologies and we also compared the application-layer performance over these camera networks using different physical-layer protocols and MAC-layer configurations. We found that the 10-node single-hop camera network in the residential house provided reasonable application quality, if hidden-terminal protection mechanism is used. On the other hand, the 15-node multi-hop camera network in the office building suffered throughput unfairness across cameras, leading to unacceptable application performance for the cameras that are more than one hops away from the server. One possible solution is to use multiple radios on individual cameras, as our experiments showed great performance improvement. We observed that the suitable choices of several network parameters are often dependent on the radio environment, and network-layer throughput is not sufficient to predict the performance of camera applications. These results suggest cross-layer joint network optimizations must be tailored to meet the specific requirements of the applications using distributed cameras.