5.1 Introduction

Mobile devices with wireless network interfaces have gone through a tremendous evolution in recent years. From around 1992 to 2002 the main development goal was to make these devices smaller. While during that time the form factor of phones shrank considerably, voice telephony and SMS texting remained the only two real applications and overall functionality changed very little. By around 2002, technology had developed to a point where it became impractical to shrink phones any further from a usability point of view. The Panasonic GD55 is one of the smallest mobile phones ever produced, with a weight of just 65 g, and is smaller than a credit card [1]. Since then, development has concentrated on adding additional multimedia functionality to....