Brief descriptions of the six major layers of a mobile OS are given below:
Mobile applications: This level refers to customer-level applications such as microbrowsers and mobile retailing.
Graphical user interface (GUI): Applications use the API to display information on the GUI.
Application programming interface (API) framework: This level provides the framework between the low-level architecture components and the application layer. By using this framework, application developers do not need to know the underlying low-level details in order to take full advantage of their capabilities.
This level consists of three components:
Multimedia: This module involves image/video related functionality, audio recording and play back, etc.
Communication infrastructure: It may contain wide-area networking stacks, personal area networking stacks, and GSM and CDMA circuit-switched voice and data and packet-based data.
Security: It may include authentication, cryptography, secure communications, secure mobile payment methods, etc.
The 5th level also consists of three components:
Computer kernel: This is the central module of an operating system and it provides all the essential services required by the other parts of the operating system and applications.
Power management: This component manages the power consumption to prolong the battery life.
Real-time kernel: Handheld devices need real-time responses for some time-critical applications such as voice communication.
The bottom level is the hardware controller. The hardware includes displays and memory. It is expected that hard disks will be added to the list in the near future.
