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II
Advanced Mobile App Optimizations
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CHAPTER 5
Mobile Embedded System Architecture
CONTENTS
5.1 Embedded Systems
5.1.1 Embedded Systems Overview
5.2 Scheduling Algorithms
5.2.1 Basic Concepts
5.2.2 First-Come, First-Served Scheduling Algorithm
5.2.3 Shorted-Job-First Scheduling Algorithm
5.2.4 Multiprocessors
5.2.5 Priority Scheduling Algorithm
5.2.6 ASAP and ALAP Scheduling Algorithm
5.2.6.1 ASAP
5.2.6.2 ALAP
5.3 Memory Technology
5.4 Mobile Embedded Systems
5.4.1 Embedded Systems in Mobile Devices
5.4.2 Embedded Systems in Android
5.4.3 Power Management of Android
5.4.4 Embedded Systems in Mobile Apps
5.5 Messaging and Communication Mechanisms
5.5.1 Message Mechanisms
5.5.2 Communication Mechanisms
5.6 Exercises
Mobile DEVICE is the indispensable part of a mobile system, and all the chips used in a mobile device are embedded systems. These embedded systems with various functions are controlled by the mobile operating system and collaborate with each other to complete every task mobile apps request.
In this chapter, we introduce the mobile embedded system architecture, including:
Overview of embedded systems
Applications of embedded system.
The processor technology in embedded systems
Basic concepts in processor technology in embedded systems
The scheduling algorithms in processor technology in embedded systems
Memory technology in embedded systems
Embedded systems in mobile devices
Embedded systems in Android
5.1 EMBEDDED SYSTEMS
5.1.1 Embedded Systems Overview
Embedded systems are anything that uses a micoprocessor but is not a general-purpose computer. An embedded system is a computer system with a dedicated function, which is embedded as a part of a complete device, including hardware and mechanical parts [60]. These tiny systems can be found everywhere, ranging from commercial electronics, such as cell phones, cameras, portable health monitoring systems, automobile controllers, robots, and smart security devices, to critical infrastructure, such as telecommunication networks, electrical power grids, financial institutions, and nuclear plants [61, 62, 63]. The increasingly complicated embedded systems require extensive design automation and optimization tools.
Modern embedded systems are often based on microcontrollers [64, 65], such as Central Processing Unit (CPU)s with integrated memory or peripheral interfaces, but ordinary microprocessors, which use external chips for memory, and peripheral interface circuits are still common. Embedded systems are commonly used in telecommunication systems, consumer electronics, transportation systems, and medical equipment [66].
Telecommunication Systems
Telecommunication systems employ numerous embedded systems, from telephone switches to cell phones.
Consumer Electronics
Consumer electronics include personal digital assistants (PDAs), such as audio players, mobile phones, videogame consoles, digital cameras, video players, and printers. Embedded systems are used to provide flexibility, efficiency, and features.
Home Automation
Embedded devices are used for sensing and controlling in-home automation using wired and wireless networks. Embedded devices can be used to control lights, climate, security, audio/visual, and surveillance.
Transportation Systems
Embedded systems are increasingly used from flight to automobiles in transportation systems. New airplanes contain advanced avionics, such as Inertial Guidance Systems (IGS) and Global Positioning System (GPS) receivers that also have considerable safety requirements. Various electric motors use electric motor controllers. Automobiles, electric vehicles, and hybrid vehicles increasingly use embedded systems to maximize efficiency and reduce pollution.
Medical Equipment
Medical equipment uses embedded systems for vital signs monitoring, electronic stethoscopes for amplifying sounds, and various medical imaging for non invasive internal inspections. Embedded systems within medical equipment are often powered by industrial computers.
Besides the usages mentioned above, embedded systems are also widely used in a new kind of technology, which is wireless sensor networking (WSN). The WSN consists of spatially distributed autonomous sensors to monitor physical or environmental conditions. Commonly monitored parameters are temperature, humidity, pressure, wind direction and speed, illumination intensity, vibration intensity, sound intensity, power-line voltage, chemical concentrations, pollutant levels, and vital body functions [67]. WSN enables people and companies to measure myriad things in the physical world and acts on this information under the help of embedded Wi-Fi sys...
