Descripción



A number of applications in wireless sensor networks (WSN) require sensor nodes to obtain their absolute or relative positions. Equipping every sensor with a GPS receiver may be expensive, en ergy prohibitive and limited to outdoor applications. Therefore, we consider cooperative localization where each sensor node with unknown location obtains its location by cooperating with neighboring sensor nodes. In this chapter, we apply probabilistic inference to the problem of cooperative localiza tion. These techniques are capable to obtain, not only location estimates, but also a measure of the uncertainty of those estimates. Since these methods are computationally very expensive, we need to use messagepassing methods, which are also known as belief propagation (BP) methods. BP is a way of organizing the global computation of marginal beliefs in terms of smaller local computations within the graph. It is one of the bestknown probabilistic methods for distributed inference in statistical physics, articial intelligence, computer vision, errorcorrecting codes, localization, etc. The whole computation takes a time proportional to the number of links in the graph, which is signicantly less than the exponentially large time that would be required to compute marginal probabilities naively. However, due to the presence of nonlinear relationships and highly nonGaussian uncertainties the standard BP algorithm is undesirable. Nevertheless, a particlebased approximation via nonpara metric belief propagation (NBP) makes BP acceptable for localization in sensor networks. In this chapter, after an introduction to cooperative localization, we describe BP/NBP techniques and its generalizations (GBP) for the loopy networks. Due to the poor performance of BP/NBP methods in loopy networks, we describe three improved methods: GBP based on Kikuchi approximation (GBPK), nonparametric GBP based on junction tree (NGBPJT), and NBP based on spanning trees (NBPST). The last one (NBPST) is currently a unique method which is computationally feasible in a largescale WSN.  
Internacional

Si 
DOI

DOI: 10.1002/9781118104750.ch25 
Edición del Libro


Editorial del Libro

John Wiley & Sons 
ISBN

9781118104750 
Serie


Título del Libro

Handbook of Position Location: Theory, Practice, and Advances 
Desde página

837 
Hasta página

869 