The focus of this study is the optimal configuration of a wireless low-power duty-cycled network with respect to theminimal energy consumption. Precisely, the energy consumption of a truncated-ARQ scheme in realistic shadowing environments is examined for the reference IEEE 802.15.4e standard protocol and for its cooperative extension that is presented in the paper. We show how to choose betwee...

We present the real-world evaluation of SPIDA, an electronically switched directional antenna. Compared to most existing work in the field, SPIDA is practical as well as inexpensive. We interface SPIDA with an off-the-shelf sensor node which provides us with a fully working real-world prototype. We assess the performance of our prototype by comparing the behavior of SPIDA against traditional om...

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Dark line resonances, narrowed with a buffer gas to less than 100 Hz width, are observed in a Cs vapor cell using a directly modulated vertical-cavity surface-emitting laser (VCSEL). An external oscillator locked to one of these resonances exhibits a short-term stability of ( ) = 9 3 10 12 , which drops to 1 6 10 12 at 100 s. A physics package for a frequency-reference based on this design coul...

A corollary of Hilbert’s basis theorem is that any antichain in the set of n-dimensional vectors with non-negative entries is finite. In other words, any antichain in the poset given by cartesian powers of semi-infinite chains is finite. We study several variations of this result. We provide necessary and sufficient conditions for antichains in the cartesian product of posets to be finite or bo...