Date of Award
Doctor of Philosophy
Electrical and Computer Engineering
Terry A. Smay
The first ground wireless packet switching radio network, named the ALOHA network, was implemented in the early 1970s at University of Hawaii. The most distinct features of a packet radio network are: (1) the absence of physical connections between users, (2) the sharing of a common transmission medium, and (3) the broadcasting capability of each user. Today, the packet radio network technology is widely used in a variety of civilian as well as military applications;The throughput of a packet radio network is defined as the percentage of time the channel carries good packets. It is largely determined by the channel access method, the signal propagation characteristics, and the capture effect at a receiver. In this dissertation, we present two packet radio network models under the Slotted ALOHA channel access method and a capture model which is based on the relative strength of signal powers of the desired packet and the interfering packets;The first model is a single-hop network with a central station and finite number of users randomly distributed in a limited area. All the users communicate with each other through the central station, which is within one hop distance of all users. Given a density distribution function for the distance of a user, we show that there is an optimal transmission probability which maximizes the throughput of the network. Also, under a light traffic load, the throughput of a remote user is relatively insensitive to its distance from the station;The second model is a multi-hop network where a user is equipped with a directional antenna and not every user can directly communicate with every other else. As a result, a user communicates with another user either directly in a single hop or through some intermediate users in multiple hops. The location of all users is modeled by a two-dimensional Poisson process with an average of [lambda] users per unit area. By balancing the transmission probability and the antenna beam width, we show that the maximum hop-by-hop progress of a packet can be achieved when the transmitter and the receiver are separated by an optimal distance.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/
Wang, Yangwei, "Performance evaluation of packet radio networks " (1988). Retrospective Theses and Dissertations. 8900.