Mobile and Ubiquitous Computing

Objectives

To give students an overview of the fields of mobile and ubiquitous computing, and an appreciation of their challenges and opportunities. By the end of the chapter, students should be able to give an account of how these systems differ from more conventional, wired distributed systems. They should be able to give an account of the challenges they raise that do not have solutions among the algorithms and techniques in the remainder of the book. They should develop a healthy sense of how difficult some of these new challenges are, and how little exists by way of solutions. They should be inspired to solve them!

Points to emphasize

That system volatility is a major characteristic of the systems under study. This fact, and the fact that volatility arises here principally out of integration with the physical world, are key. Energy and other resource limitations, and changes in associations and connectivity are especially important to emphasize.

The student should be encouraged to ask two critical questions of any system they are studying: (1) how is physical integration (a) utilized or (b) a constraint in this system? And (2) how wide a set of components could participate in – that is, interoperate within – this system?

Possible difficulties

Students may find the coverage of some topics to be on the brief side, and some of the papers cited in the chapter – as well as others – will need to be covered to gain a proper appreciation.

Students may be unfamiliar with some of the sensors mentioned in this chapter such as accelerometers, and other technologies used for physical association and in physically constrained channels (infrared, camera-based barcode reading, etc.). It should help to ask them each to do some background research into one particular technology and report to the class.

It will help to go over at least one paper about sensor networks in detail. The algorithms can be quite complex. Similarly, it will help to go into the basic physics of at least one location technology in more depth than there is space for in the book – especially so as to give the student an understanding of the error modes involved. Areas in cities where GPS performs poorly are a good example.

Thinking about security and privacy in ubiquitous and mobile computing requires something of a different mindset. For example, logging in is rarely a helpful mechanism (if it is, then the system is probably not spontaneous and we have gone back to talking about conventional distributed systems). It may help to get the students thinking about a practical example, such as how a café’s owners could restrict access to their services to people drinking their coffee.

For an appreciation of the problems of adaptation, it may help to to ask students to take any web home page and to sketch a concrete design for the “same” page on a mobile phone – and then to think how that transformation could have been achieved (if at all) automatically.

Teaching hints

The contents of this chapter represent one relatively brief perspective on what are very large fields of research. The instructor will probably want to select from among the topics and add material from several other authors.

Mobile phones – and the forms into which they might evolve – are often good examples, which help make the subject concrete. Similarly, RFID tags (which many students will have read about) and GPS will often be familiar.