Modeling for Geo-Routing in Multi-Hop Wireless Networks - Application and Multidisciplinary Aspects of Wireless Sensor Networks - page 160

7.9 Conclusions

In this work we have shown that a meaningful assessment of a geographic, position-
based routing protocol can only be achieved through careful incorporation of the
physics of radio wave propagation in simulations. We demonstrate that UDG-based
models, and models that fail to take into account the fully correlated spatial
distribution of link reliability, significantly over-predict the end-to-end path hop
count. The only geographic routing algorithm that has been found to be capable of
exploiting the distant neighbor forwarding opportunities that occur in physically
realistic radio wave propagation environments, and thus exploited end-to-end paths
requiring fewer hops, is the localized probabilistic progress algorithm [ 15 ]. The
corollary to this conclusion is that failing to adopt a physically accurate model for
radio wave propagation can under certain circumstances ( y = 1 and

σ≥ )
produce pessimistic results on this protocol's performance in simulations.
We have provided a complete overview of the manner in which the physical
radio environment needs to be modeled. Furthermore, we have identified three
parameters that are required in order to meaningfully characterize position-based
routing and provided a geometric interpretation for these:

8dB

dB

• The angular spread of regions of higher than average range for a given probabil-

ity of packet reception, y , which is determined by the shadow fading de-corre-
lation length and the notional node transmission radius
The extent to which such regions are pronounced, given by the shadowing

•

standard deviation

σ
The average local node density,

dB

• k , which ultimately determines the probability

with which such regions are populated by neighboring nodes that are likely to
receive packet transmissions successfully

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