Brief descriptions of the six 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 (Application Programming Interface) to display information on GUI.
API framework:
It provides the framework between the low-level 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 WAN stack, 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:
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:
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 (both RAM and flash).