Position-Based Routing Protocols for Ad Hoc Networks - Application and Multidisciplinary Aspects of Wireless Sensor Networks - page 53

Fig. 4.6 Example of the expected region in DREAM

Figure 4.6 gives an example for the expected region in DREAM. If a node does
not have a one-hop neighbor in the required direction, a recovery procedure has to
be started. However, this procedure is not part of the DREAM specification [ 6 ].
Since DREAM uses the restricted directional flooding to forward data packets
themselves, there will be multiple copies of each packet at the same time. This
increases the probability of using the optimal path; however, it decreases its
scalability to large networks with a high volume of data transmissions and makes it
more suitable for applications that require a high reliability and fast message delivery
for infrequent data transmissions.

4.3.6 LAR

Like DREAM, Location-Aided Routing (LAR) [ 12 ] is an example of restricted direc-
tional flooding routing protocols; however, partial flooding is used in LAR for path
discovery purpose and in DREAM for packet forwarding [ 24 ]. Hence, LAR does not
define a location-based routing protocol but instead proposes the use of position
information to enhance the route discovery phase of reactive Ad Hoc routing
approaches [ 6 ]. If no information is available in the source about the position of the
destination, LAR is reduced to simple flooding [ 6 ]. Otherwise, the expected zone (the
area containing the circle and two tangents) is fixed from the source and defined