erations of the devices (i.e., logic). To process the digital signals, devices use either digital signal processors (DSPs) or application integrated circuits (ASICs). The UMTS phones require over 40- 60 MIPS, compared to less than 1 MIPS (Million Instructions per Second) system processing required by analog cellular phones. Speech coding, channel coding, data processing and USIM (only for 3GPP devices) functionalities exist in this section. The user interface allows the user to originate and respond to calls, messages and data communications. This interface at a minimum consists of audio input (microphone) and output (speaker), display unit, keypad and accessory connectors to allow battery chargers and other devices to be connected to the mobile phone. In the last few years, we have also witnessed incorporation of touch screens, external memory slots and sensors in the user interface. The power supply provides the resource necessary to operate the devices. Power is usually supplied by internal rechargeable batteries but other sources such as car batteries or cigarette lighter sockets can be used as well. Mobile Software Platform A Software Platform or Mobile Software Platform provides an environment for the development and execution of applications, thus creation of new device applications is related to the software platform closely. A software platform is a set of products, services, and tools that help users to develop, and deliver their applications effectively. The most common platforms that can be found on today's mobile devices include Symbian, Windows Mobile, Palm, Blackberry, iPhone, Android (Linux-based), Linux, Brew, Java, and REX. Figure 10.2 shows a high level architecture of a software platform consisting of operating system (OS), middleware, and applications. The operating system manages the hardware resources and controls applications when processes use the system resources. Different software platforms use different operat- ing systems, for example, Symbian uses Symbian os while iPhone is based on