We investigate the properties of data collection in wireless sensor networks, in terms of both capacity and power allocation strategy.\nWe consider a scenario in which a number of sensors observe a target being estimated at fusion center (FC) using minimum meansquare\nerror (MMSE) estimator. Based on the relationship between mutual information and MMSE (I-MMSE), the capacity of\ndata collection in coherent and orthogonal multiple access channel (MAC) models is derived. Considering power constraint, the\ncapacity is derived under two scenarios: equal power allocation and optimal power allocation of bothmodels.We provide the upper\nbound of capacity as a benchmark. In particular, we show that the capacity of data collection scales as T((1/2)log(1 + ??)) when the\nnumber of sensors L grows to infinity. We show through simulation results that for both coherent and orthogonal MAC models,\nthe capacity of the optimal power is larger than that of the equal power.We also show that the capacity of coherent MAC is larger\nthan that of orthogonal MAC, particularly when the number of sensors L is large and the total power P is fixed.
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