Research and Analysis of 3G Mobile Operating System

1 Introduction

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With the advent of the mobile multimedia era and the rise of 3G wireless communications, the popularity of digital broadcasting. Coupled with the adoption of a variety of next-generation advanced video compression algorithms, mobile phones have evolved from simple call tools to smart ones. With its operating system and rich application software. The smartphone becomes a microcomputer. The mobile operating system as its core has also become a hot topic of current discussion and research. In addition to the full functionality of an ordinary mobile phone, the smartphone also has most of the functions of a PDA (Personal Digital Assistant), in particular, a personal information management system can be established. With browser and email capabilities based on wireless data communication. And more applications can be installed on this open platform. This allows the functionality of the smartphone to be expanded indefinitely. Determine if a phone is a smartphone. Mainly depends on whether it is a mobile phone with an operating system.

At present, there is no operating system in the field of smart phone operating systems that can occupy a monopoly in smart phones like the Microsoft operating system. Still a situation where multiple operating systems coexist and compete.

At present, the operating systems used by smartphones mainly include: Windows CE operating system (OS) launched by Microsoft, Symbian operating system with Nokia as the main sponsor, Palm operating system, Linux operating system, Google Android mobile phone platform, and Apple's iPhONe operating system. .

2 3G smartphone's main features

3G services can be divided into several different categories according to different levels. According to the business-oriented business, it can be roughly divided into: communication services, information services, entertainment services, Internet services, mobile commerce, and location services.

(1) Communication business

The communication services of 3G mobile phones mainly represent high-quality call functions and videophone functions. That is to say, not only can you hear the clear voice of the other party when you call. You can also see the other party's movements and expressions. The anti-interference ability of the call signal is high, the call quality is strong, the call drop frequency is greatly reduced, and the performance of the video call is stable.

(2) Information business

Based on the large capacity and high speed of 3G networks, the information services provided by operators include the pure text content of the 2G era, and more interactive communication of information content through multimedia. For example, a typical video application - the video community. Old students and old colleagues can form a community. No matter in the north and south, everyone can meet regularly and communicate and communicate through community activities.

(3) Entertainment business

The 3G smartphone entertainment business includes IP-based video applications.

Applications based on a variety of audio and video content sources and applications based on wireless audio and video transmission needs in home entertainment devices.

(4) Internet business

3G is considered to be a typical application for a high degree of convergence between mobile communications and the Internet. If it is a long time, for example, a few hours of Internet access. Using a 3G phone may not be as good as a computer (such as a mobile phone battery capacity limit), but as a short-term, mobile Internet connection, using a 3G mobile phone is very convenient and fast.

(5) Mobile commerce

Mobile commerce mainly includes mobile payment, mobile banking, mobile retail, mobile ticketing and other services. The mobile payment function means that the communication carrier can "bundle" the customer's mobile phone number with a payment account such as a bank card. Provide mobile payment services to 3G mobile phone users anytime, anywhere. Research data shows. The 3G mobile phone function that users are most interested in is the “mobile wallet”. The proportion accounted for 46.2% of the number of users surveyed. This feature fully embodies the mobility, portability, and personalization features of mobile terminals.

(6) Location service business

The location service business mainly includes trigger service, information service, tracking service and rescue service. The main goal is to provide users with security services and personalized and personal services. Such as the positioning function provided by 3G mobile phones. Make the user wherever they go. Both can be accessed via an electronic map on the phone. Find nearby hospitals, restaurants, etc. quickly and easily.

As can be seen from the functions of the above featured businesses, the 3G smartphone will gradually become a micro computer, and users can install various additional applications. Let its function be expanded infinitely: users can also set the phone according to their own preferences, making it a representative of self-personality.

3 smart phone operating system comparison

The smartphone operating system acts as a software platform for smartphones. Manage the hardware and software resources of the smartphone to provide all necessary services for the application software. The adoption of the mobile operating system enables application developers to avoid cumbersome hardware management and operational programming, focusing on the algorithmic research of the target application and the architecture of the application itself: simultaneously applying various kinds of functions provided by the smartphone operating system. Services make it easier to build complex smartphone applications.

It can be said that every smartphone operating system has its own advantages.

Their architecture and the services they provide are not the same. The particularity of the smartphone itself raises many common requirements for the smartphone operating system, such as real-time, openness, security, and hardware support capabilities. The following analysis and comparison of the current major smartphone operating systems will be carried out in terms of real-time, openness, security, and hardware support capabilities.

3.1 Real-time

Real-time performance is a very important feature of smartphone operating systems.

It is also an important indicator that needs to be measured first when choosing a smartphone operating system. In order to enhance the real-time performance of the system, the smartphone operating system usually starts from many aspects and applies various technologies in order to achieve this goal. Key metrics that measure the real-time nature of the operating system include task switching time, interrupt response time, and timer precision.

(1) Linux

Linux did not have any consideration for real-time performance at the beginning of its design. The main consideration is resource sharing. Maximize throughput. However, with the rapid development of Linux, its application range has far exceeded the original idea. Lin's openness and its support for multiple architectures make it widely used in embedded systems, but the real-time requirements of many embedded systems have made Ijnux's application in the embedded field hindered. People are demanding more and more real-time voices from Linux.

In Linux 2.4 and previous versions. The kernel is not preemptible. That is, if the current task is running in kernel mode, even if there are more urgent tasks that need to be run. The currently running tasks cannot be preempted. The emergency tasks must wait until the current task has finished executing the kernel mode and return to the user mode.

Or the current task can be considered for execution because it needs to wait for certain conditions to meet and actively release the CPU. Obviously this will seriously affect the preemption delay.

In Linux 2.6. The kernel is already preemptible. As a result, real-time performance has been enhanced, but there are still a large number of non-preemptable areas in the kernel, such as critical sections protected by spinlocks and critical sections that are explicitly preempted by preempt disable.

In Linux 2.4 and previous versions. The time complexity of the scheduler is O(n) algorithm, and the performance is lower in the case of SMP (symmetric multi-processing), because all CPUs share a task list, and there can only be one schedule at any time. The device runs, so the preemption delay is largely dependent on the number of tasks in the current system, with very large uncertainties and instabilities.

(2) Windows CE

Windows CE is not a real-time kernel in a strict sense.

But it is specifically designed for embedded systems. It supports nested interrupts, allowing higher priority interrupts to get a response first. Instead of waiting for a low-level ISR (interuption service routine) to complete. This allows the operating system to have the real-time nature required by the embedded operating system, while having better thread responsiveness. Windows CE has stricter requirements on the upper response time limit of high-level IST (interrupt service thread), and has improved the thread response capability to help developers grasp the specific time of thread conversion. And help them create new embedded applications with enhanced monitoring capabilities and control over hardware. Also. The Windows CE system has 256 priority levels. It allows developers greater flexibility in controlling the timing of embedded systems.

(3) Palm OS

Palm OS is a set of OS developed specifically for handheld computers. When writing a program. Palm OS takes into account the relatively small amount of memory on your handheld.

So it only takes up very little memory. Because the application written on the Palm OS takes up very little space (usually only a few tens of KB). Therefore, Palm OS-based handheld computers only have a few MB of RAM. But you can run many applications. And have better real-time performance. Simultaneously. Palm OS has reasonable memory management, and its memory is all fast readable and writable RAM.

There are two types of RAM: dynamic RAM and static RAM. Dynamic RAM is similar to RAM on a PC. It provides temporary storage for global variables and other data that does not need to be permanently saved. Static RAM is similar to a hard disk on a PC and can permanently store applications and data.

(4) Symbian

The EKA2 core is used in Symbian 9.0 and later. EKA2 has completely improved the original task scheduling algorithm. Full support for real-time, supporting the basic real-time requirements of certain high-bandwidth, high-priority tasks on the system. These tasks include VolP VoIP, high-speed video on-demand. EKA2's improvements include: real-time kernel enhancement, better multi-threading, API calls are more efficient and faster, and are a true 32-bit operating system.

(5) Google Android

C, oosle Android mobile phone platform is a complete mobile phone software development platform using Lint= as the kernel. It has a separate application framework and Java virtual machine. The real-time nature of the kernel can refer to the Linux part.
3.2 openness

 

Openness means that people can write software to expand the functions of the system, implement complex calculations, and provide a convenient modular programming method for very large programs. Therefore, opening the operating system is beneficial for other developers to fix the deficiency of the operating system. Make it more perfect and powerful.

Linux complies with the GPL (GNU General Public License) and opens the source code. For example, Google Android's Linux operating system is a completely open, free user interface with complete source code. Since GoogleAndroid's smartphone platform is an open system, open source code supports third-party software to join. The Google Android smartphone can load a lot of personalized software, such as firewall, instant messaging software, Office reading software and various software installed on the computer. The function of the mobile phone is more powerful, which accelerates the integration of mobile phones and computers. At the same time, unlike Windows CE and Symbian, the Android operating system is freely available to developers. There are no proprietary barriers that hinder the innovation of the mobile industry, which can save a lot of research and development costs for third-party vendors.

Windows CE is a closed operating system, and its software Windows is commercial software. Its source code is the top secret of the enterprise, so it is impossible to open.

Use software like Visual C++. Third parties can develop applications for Windows CE. Windows CE also uses a similar window. NET framework. But all usage and services are charged.

Symbian also has no open source. But according to Nokia's recent announcement, Symbian will also have an open source plan. The Symbian Foundation has released its first open source software program, which is the first step to open the entire Symbian mobile operating system.

Palm OS is an open system. Developers provide Palm OS development tools to users free of charge. Allow users to use the tool to easily write and modify related software on the basis of Palm OS.

iPhone OS X is a limited SDK (software development kit) that ensures that programmers can take advantage of the all-around OS without having to go deep into the core. In other words, the core is not completely open.

Given that RIM's mobile phones handle mostly corporate email and confidential information, this makes opening up its operating system less suitable. And it will have a certain impact on the privacy protection of users.

3.3 Security

The security issues of smartphone operating systems are mainly focused on the security threats faced after accessing voice and data networks. For example, is there a vulnerability in the system that can cause security problems? Whether the security of information storage and transmission is guaranteed, whether it is threatened by malware such as viruses. Because there are more mobile phone users than computer users. And smartphones can offer a variety of data connections. Therefore, the virus is a very serious security threat to mobile phone systems, especially smart phone operating systems. The author mainly compares the smartphone operating systems against the above several security aspects.

There are some security holes in the Symbian system itself. So it is currently the most affected by the virus. More than 50 viruses have been discovered for Symbian.

These viruses usually infect the Symbian 6.0 system. The UiQ platform is rarely infected. The widely known Cabir virus is a DoS attack on Symbian phones via a Bluetooth connection. As more and more personal information (such as phone books, business secret documents, etc.) is saved in the smartphone. In order to prevent malware or viruses from stealing this information or costing user communications, Symbian 9.0 and later introduces a new system security model.

All files of a software installed on a system before Symbian 9.0 will be stored in the ksystemappskxxx directory. In Symbian 9.0 and later systems, different files in a certain software will be stored in different directories. For example, the executable file (.exe, formerly .app) is placed under ksys and bin, and the resource file is placed under h'esource. All private data for each software is placed in the private directory, and other directories are directories shared by all software. The sysbin and hresource users cannot be changed. Executable files can only be copied by the installer. Private can only be accessed by the software corresponding to the software security number. The executable introduces a capability model that takes certain capabilities such as accessing the user's phone book, sending text messages, modifying phone settings, etc., and requires the executable to be digitally signed by Symbian or Nokia. The system also has an executable file tamper-proof function and installs a modified software package. Or use a card reader to modify the ksyskbin directory of the memory card. Will be discovered by the Symbian system. Introduce these features. The security of the system is greatly improved. However, the introduction of the system security model has also led to compatibility issues in the system.

The Windows CE system for SmartPhone has also found some cases of virus infection. The enthusiasm of the virus authors for the Microsoft platform has continued on the mobile phone system. Windows CE systems have long been found to have security vulnerabilities. A typical vulnerability is to allow an attacker to send malicious code to a mobile phone using the system, much like a Windows-based PC system.

Palm and Linux systems perform better in terms of security vulnerabilities, but this includes the impact of market share. Attackers are often more interested in exploiting vulnerabilities on systems with outstanding market share. Currently, vendors are able to fix discovered security vulnerabilities in a short period of time. As long as users update security patches in a timely manner, they can avoid the harm caused by the vulnerability.

The newly released Palm operating system provides security protection. The new security features will ensure the confidentiality of sensitive data. It mainly provides a powerful 128-bit data encryption service (the service is based on the RSA Security standard RC4 encryption algorithm) and the end. Peer security (provided by secure socket layer (SSL) services for email, web browsing, and online transactions). For developers writing applications for Palm, these new security features mean they have the foundation to build powerful cryptography and security protocols designed by security experts. Palm's goal is to simplify the development of secure applications on its platform by providing a robust security foundation that developers can "hang in."

In general, due to the security experience in the personal computer field, mobile operating system vendors have fully considered security issues when designing systems. These vendors have made many security enhancements in data encryption, communication protocols, and access authentication methods, and are still actively improving.

Just use these features correctly and some existing security solutions.

Keeping proper attention to all kinds of information released by vendors, current smartphone users can get a good security environment.

3.4 support for hardware

Due to the diversity of smartphone hardware platforms. The CPU chip update is very fast. Therefore, the smartphone operating system is required to support commonly used embedded CPUs, such as X86, ARM, MIPS, POWERPC, etc., and has good portability and supports a wide variety of external devices.

Linux supports most popular embedded processors, including 32-bit architectures such as Alpha, ARM, Cris, X86 M68K, MIPS, PARISC, PPC, SH, Spare, etc. Supported 64-bit architectures include MIPS64 and PPc64. , SH64, Spare64, X86_64, etc.

Windows CE only supports ARM, MIPS, X86, and SuperH.

Symbian can support all ARM processors from the ARM9 family to the ARM11 family. Symbian OS v9.5 is the industry's first smartphone operating system to support the ARM Cortex-A8 processor.

Processors supported by Palm include Motorola DragonBall, Xscale, and others.

The processor supported by the iPhone is ARMl 176JZF.

Black Berry supports processors such as PXA9xx and PXA270.

4 Conclusion

The development direction of 3G smart phone operating system is bound to meet the "mobile broadband" application of multimedia functions such as multimedia applications, wireless Internet access, mobile TV, mobile phone positioning and other data functions. It should be able to handle a variety of media formats such as images, music, and video streams. Provide a variety of information services including web browsing, conference calls, e-commerce and more. Simultaneously. The 3G smartphone operating system should strive to achieve a unified platform. Overcome formatting issues. Provides more flexible features and allows users to decide on features. To meet individual needs. Therefore, the future of the mobile phone market will be based on wireless Internet applications, and the proportion of hardware prices will continue to shrink. Mobile phone companies no longer rely on mobile phones for profit, relying on software and value-added services.

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