Fig. 1. Process diagram. RTIs gather on allocated grid rectangles within the
expedition floor, and they get loaded into a trailer according to a precise
loading list.
- Nodes may often need to directly exchange data. The
abstraction framework should provide the
appropriate communication abstractions to
efficiently take care of this.
- Whenever necessary, rules carried by the nodes can
be changed or updated. Transfer of rules to the nodes
must be possible after the network is in operation,
and should be done in an efficient way. A compact
and flexible representation of the rules will therefore
be required.
B. Localization
In the previous section we have outlined the need for
localization support. This is a topic that has received much
attention, and a wide variety of solutions have already been
developed. Section VI elaborates more extensively on existing
localization systems.
Although addition of specialized hardware on the nodes –
which is needed for e.g. ultrasound localization – allows for
additional information about placement and distance of other
nodes or beacons and thus has the potential to increase
localization accuracy, it dramatically increases costs.
Furthermore, some specialized hardware is quite vulnerable to
shocks or rough handling or not usable at all since it requires
line-of-sight.
A measurement that (often) does not require specialized
hardware is Received Signal Strength Indication (RSSI), but
usability is still a point of discussion and dependent on the
environment of deployment and quality of the transceiver
[5][6]. The high density of nodes, the fact that RTIs are made
of metal and the absence of reliable experimental RSSI data