The work reported in this paper has formed part of the Core 3 Research Programme of the Virtual Centre of Excellence in Mobile & Personal Communications, Mobile VCE, http://www.mobilevce.com, whose funding support, including that of EPSRC, is gratefully acknowledged. More detailed technical reports on this research are available to Industrial Members of Mobile VCE.

I would also like to thank Graeme Proudler, HP (TCG); Marcus Peinado, Microsoft; David Grawrock, Intel; Don Felton, ARM; and Edward Suh, who made themselves available to answer any questions and clarify any queries that arose in relation to the respective technologies with which they are involved.