A d v a nce d I n fo rm a t i o n

24

Linear Technology / Dust Networks

Eterna Datasheet

9.0

Typical Performance Characteristics

Network motes typically route through at least two parents traffic destined for the manager. The bandwidth and keep-alive

overhead required to support network motes will be shared across all of the mote's parents. The supply current plots include a

parameter called traffic-weighted descendants. In these graphs the term traffic-weighted descendants refers to an amount of

activity equivalent to the number of descendants were all of the network traffic and keep-alives directed to the mote in

question. Generally the number of descendants of a parent is more (typically 2x or more) than the number of traffic-weighted

descendants. For example, with reference to Figure 25 mote P1 has 0.75 traffic-weighted descendants. To obtain this value

notice that mote D1 routes half its packets through mote P1 adding 0.5 to the traffic-weighted descendant value; the other

half of D1's traffic is routed through its other parent, P2. Mote D2 routes half its packets through mote D1 (the other half

going through parent P3), which we know routes half its packets to mote P1, adding another 0.25 to the traffic-weighted

descendant value for a total traffic-weighted descendant value of 0.75.

Figure 25 Network Graph Depicting Traffic Weighted Descendant Value Calculation

The following plots correspond to networks with a P2 bandwidth profile, an assumed path stability of 80%, an 80 byte packet

and unless otherwise specified operation at 25 degrees C.