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In this paper, we propose a novel routing model that can comprehensively depict multiple service requirements in multimedia sensor networks, and on the basis of this model, we design a new multi-constrained routing algorithm MCRA for multimedia communications. MCRA not only can provide end-to-end delay and packet loss ratio guarantees, but also can optimize and balance the energy consumption in sensor nodes. Compared to the congener algorithms, in MCRA, neither the acquisition of target location nor the route discovery requires any extra measurement equipment or coordinate system based on location message exchange. Besides, MAC differentiation service may optionally be applied in MCRA so as to differentiate forwarding priority levels for real-time and best-effort data in MAC layer. Theoretical analysis and simulation experiments are provided to validate our claims.

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We introduce the concept of local moments for a distribution in R p , p 1, at a point z # R p . Local moments are defined as normalized limits of the ordinary moments of a truncated version of the distribution, ignoring the probability mass falling outside a window centered at z. The limit is obtained as the size of the window converges to 0. Corresponding local sample moments are obtained via properly normalized ordinary sample moments calculated from those data falling into a small window. The most prominent local sample moments are the local sample mean which is simply the standardized mean vector of the data falling into the window, and the local covariance, which is a standardized version of the covariance matrix of the data in the window. We establish consistency with rates of convergence and asymptotic distributions for local sample moments as estimates of the local moments. First and second order local moments are of particular interest and some applications are outlined. These include locally based iterative estimation of modes and contours and the estimation of the strength of local association. 2000 Academic Press AMS 1991 subject classifications: 62G07, 62G20.