Computer Laboratory

Technical reports

Programming networks of vehicles

Jonathan J. Davies

November 2009, 292 pages

This technical report is based on a dissertation submitted September 2008 by the author for the degree of Doctor of Philosophy to the University of Cambridge, Churchill College.

Abstract

As computers become smaller in size and advances in communications technology are made, we hypothesise that a new range of applications involving computing in road vehicles will emerge. These applications may be enabled by the future arrival of general-purpose computing platforms in vehicles. Many of these applications will involve the collection, processing and distribution of data sampled by sensors on large numbers of vehicles. This dissertation is primarily concerned with addressing how these applications can be designed and implemented by programmers.

We explore how a vehicular sensor platform may be built and how data from a variety of sensors can be sampled and stored. Applications exploiting such platforms will infer higher-level information from the raw sensor data collected. We present the design and implementation of one such application which involves processing vehicles’ location histories into an up-to-date road map.

Our experience shows that there is a problem with programming this kind of application: the number of vehicles and the nature of computational infrastructure available are not known until the application is executed. By comparison, existing approaches to programming applications in wireless sensor networks tend to assume that the nature of the network architecture is known at design-time. This is not an appropriate assumption to make in vehicular sensor networks. Instead, this dissertation proposes that the functionality of applications is designed and implemented at a higher level and the problem of deciding how and where its components are to be executed is left to a compiler. We call this ‘late physical binding’.

This approach brings the benefit that applications can be automatically adapted and optimised for execution in a wide range of environments. We describe a suite of transformations which can change the order in which components of the program are executed whilst preserving its semantic integrity. These transformations may affect several of the application’s characteristics such as its execution time or energy consumption.

The practical utility of this approach is demonstrated through a novel programming language based on Java. Two examples of diverse applications are presented which demonstrate that the language and compiler can be used to create non-trivial applications. Performance measurements show that the compiler can introduce parallelism to make more efficient use of resources and reduce an application’s execution time. One of the applications belongs to a class of distributed systems beyond merely processing vehicular sensor data, suggesting that the late physical binding paradigm has broader application to other areas of distributed computing.

Full text

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BibTeX record

@TechReport{UCAM-CL-TR-761,
  author =	 {Davies, Jonathan J.},
  title = 	 {{Programming networks of vehicles}},
  year = 	 2009,
  month = 	 nov,
  url = 	 {http://www.cl.cam.ac.uk/techreports/UCAM-CL-TR-761.pdf},
  institution =  {University of Cambridge, Computer Laboratory},
  number = 	 {UCAM-CL-TR-761}
}