In DV-hop [29, 30], base stations flood their
positions to all nodes in the network. Sensors compute the minimum distance
in hops to several base stations. Base stations compute an average
distance per hop to other base stations, which will be flooded to the whole
network to facilitate sensors to calculate their positions. Ref. [33] refines
location estimates computed by DV-hop by using neighboring sensor positions
and distance estimates to help convergence to a better solution.
Similarly, Amorphous positioning scheme [27] also uses flooding to inform
sensors of their hop-count distances to each beacon. The di?®erence is that
Amorphous localization method improves the location estimates through
an o??ine hop-distance computation and neighbor information exchange.
The hop-counting method excludes the requirement for densely-distributed
beacons. However, the multi-hop flooding involves a large amount of communication
overhead, and relies on a network with dense and uniformlydistributed
sensors.
2.3 Secure Localization Schemes
Most of the current location discovery schemes assume a benign environment
where sensors can get correct reference information from beacons. However,
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the actual sensor networks may be deployed in hostile environments. Beacons
can be compromised, then inject false positioning information into the
network. Sensors can be misled and then claim that they are at positions
that are far away from their actual locations.
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