| Summary: | Today, third generation networks are consolidated realities, and user expectations on new applications
and services are becoming higher and higher. Therefore, new systems and technologies
are necessary to move towards the market needs and the user requirements. This has driven the
development of fourth generation networks.
”Wireless network for the fourth generation” is the expression used to describe the next step
in wireless communications. There is no formal definition for what these fourth generation
networks are; however, we can say that the next generation networks will be based on the
coexistence of heterogeneous networks, on the integration with the existing radio access network
(e.g. GPRS, UMTS, WIFI, ...) and, in particular, on new emerging architectures that are obtaining
more and more relevance, as Wireless Ad Hoc and Sensor Networks (WASN). Thanks to their
characteristics, fourth generation wireless systems will be able to offer custom-made solutions and
applications personalized according to the user requirements; they will offer all types of services
at an affordable cost, and solutions characterized by flexibility, scalability and reconfigurability.
This PhD’s work has been focused on WASNs, autoconfiguring networks which are not based
on a fixed infrastructure, but are characterized by being infrastructure less, where devices have to
automatically generate the network in the initial phase, and maintain it through reconfiguration
procedures (if nodes’ mobility, or energy drain, etc..., cause disconnections). The main part of
the PhD activity has been focused on an analytical study on connectivity models for wireless ad
hoc and sensor networks, nevertheless a small part of my work was experimental. Anyway, both
the theoretical and experimental activities have had a common aim, related to the performance
evaluation of WASNs. Concerning the theoretical analysis, the objective of the connectivity
studies has been the evaluation of models for the interference estimation. This is due to the
fact that interference is the most important performance degradation cause in WASNs. As a
consequence, is very important to find an accurate model that allows its investigation, and I’ve
tried to obtain a model the most realistic and general as possible, in particular for the evaluation of
the interference coming from bounded interfering areas (i.e. a WiFi hot spot, a wireless covered
research laboratory, ...). On the other hand, the experimental activity has led to Throughput and
Packet Error Rare measurements on a real IEEE802.15.4 Wireless Sensor Network.
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