Wireless Sensor Networks

90 Chapter 3 Networking Sensors

b

c

d

s

Figure 3.8 A routing example for the GEAR protocol. Node s wishes to route a packet to node d,

but there is a network hole in between.

to d is

√

5. In the process, b will also update its learned cost to d to

be 1 +

√

5, which is larger than that of c. Thus when s wishes to send

another packet to d, it will choose neighbor c over neighbor b. The

completeness of LRTA

∗

implies that when a valid path from s to d

exists, it will always be found eventually in this fashion. However,

no performance guarantees on the quality of the actual path used or

the convergence rate can be given.

Even though there are no theoretical optimality ...