Wireless Sensor Networks : Technology, Protocols, and Applications

24 INTRODUCTION AND OVERVIEW OF WIRELESS SENSOR NETWORKS
TABLE 1.4
(Continued)
Routing
Protocol
Category Description Examples
Location Location information about the WNs can Minimum energy
based be utilized in routing data in an energy- communication
efficient manner. Location information is network (MECN)
used to calculate the distance between
and small
two given nodes so that energy consumption minimum energy
can be determined (or at least, estimated). communication
For example, if the region to be sensed is network (SMECN)
known, the query can be diffused only to Geographic adaptive
that specific region, limiting and/or
fidelity (GAF)
eliminating the number of transmissions in Geographic and
the out-of-region space. Location-based
energy aware
routing is ideal for mobile ad hoc networks, routing (GEAR)
but it can also be used for generic WSNs.
(Note that non-energy-aware locationbased
protocols designed for wireless
ad hoc networks, such as Cartesian and
trajectory-based routing, are not desirable
or ideal in WSNs.)
QoS-oriented Quality of service (QoS)–aware protocols Sequential assignment
consider end-to-end delay requirements in routing (SAR)
setting up the paths in the sensor network. Stateless protocol
for end-to-end
delay (SPEED)
Source: Based partially on [1.92].
data type, time, and location. One needs to diffuse requests and responses over the
network with application-cognizant routing; and one must support in-network data
aggregation and processing [1.75,1.76]. Some view sensor networks as being peer
to peer at the logical level, even though the physical communication topology is
generally hierarchical; here one peer is the data source that ‘‘publishes’’ the data
(could be a basic sensor node or an aggregation node) and the other peer is the
data client that subscribes to a data content list. This topic is revisited in Chapter 6.
Sensor Network Organization and Tracking Areas of interest involving network
organization and tracking include distributed group management (maintaining
organization in large-scale sensor networks); self-organization, including authentication,
registration, and session establishment; and entity tracking: target detection,
classification, and tracking. Dynamic sensor allocation (i.e., how to deal with
impaired or unreliable sensors and/or how to ‘‘clean’’ and query noisy sensors) is
also of interest. Some of the factors that come into play include the following: area