Application of embedded real-time system in communication system

In recent years, general-purpose computer systems represented by PCs have achieved rapid development in both hardware and software, and the computing speed of processors has reached the order of 1 billion times per second. The operating system, which is the core of the computer system, has also developed from the single-task, single-user DOS with a character interface to the multi-user, multi-task Windows 98 and Windows NT with a graphical interface. The application of computers has expanded to many fields such as communications, transportation, home appliances and medical care.

However, after a long period of rapid development, especially as the driving force of IT development in the past decade, general-purpose computer systems represented by PCs have shown a trend of slowing down; at the same time, the development of emerging IT requires more and more devices to be miniaturized and intelligent. In order to adapt to this development trend, a special type of system has been developed in the application process of computer systems - embedded computer systems, namely embedded systems.

Due to its simplicity and high efficiency, embedded systems have shown a strong momentum of development in recent years. With the advent of the 21st century, the IT industry has ushered in a brand new "Post-PC Era" with embedded systems as the core. As a brand new, application-oriented computer system, embedded systems not only integrate the common features of general-purpose computer systems, but also include many new technologies suitable for "embedded" applications. Therefore, the development of embedded systems has received more and more attention from people, and its powerful and flexible applicability has been widely recognized by industries such as computers, communications and information, and its use has expanded to an unprecedentedly wide range of fields. The emergence and development of embedded systems will truly realize the "ubiquitous" use of computers.

 

Because there are many technical differences between embedded systems and general computer systems, this paper first introduces the basic concepts and key technologies of embedded systems, and then explains their technical characteristics and applicability in combination with their applications in communication systems.

1 Embedded Real-Time Systems

The embedded system includes one or more control CPUs and high-level software developed for a specific application environment, usually including an operating system. During use, the behavior of the CPU and software inside the system is not perceived by the outside world, so it is called an "embedded" system; embedded systems with a very short response time to external events are usually called "embedded real-time systems"; operating systems used in embedded real-time systems are called "embedded real-time operating systems"; and corresponding applications are called "embedded real-time applications."

1.1 Composition of Embedded Real-Time Systems

Embedded real-time systems include hardware and software, and consist of three parts: hardware platform, embedded real-time operating system and other system software modules, and real-time application programs. See Figure 1. 1.1.1 Hardware Platform

The hardware platform of an embedded real-time system usually takes a compact and highly specialized CPU as the core and combines a small number of peripheral devices with application relevance, that is, diversity.

1.1.2 Embedded real-time operating system and other system software modules

The operating system and other system software are between the hardware and the application, responsible for scheduling and managing real-time applications and completing the control and operation of the hardware. [page]

1.1.3 Real-time Applications

Real-time applications are applications that are based on embedded real-time operating systems and use the real-time mechanisms provided by the operating system to complete specific functions of specific embedded real-time systems.

Among the above three parts, the embedded real-time operating system is the core of the embedded real-time system, the platform for application development and operation, the concentrated embodiment of the difference between the embedded real-time system and other general computer systems, and the key factor in promoting the widespread application of embedded real-time systems.

1.2 Characteristics of Embedded Real-Time Operating Systems

In addition to the common characteristics of operating systems, in order to adapt to "embedded real-time" applications, embedded real-time operating systems also have outstanding features such as real-time performance, microkernel combined with expansion modules to achieve universality and configurability, and the operating system does not make assumptions about peripherals.

1.2.1 Real-time

Real-time means "in time", which is a relative concept; real-time performance indicates the operating system's ability to respond to and process external events within a foreseeable time, and is one of the key indicators of embedded real-time operating system performance. To ensure good real-time performance, embedded real-time operating systems generally use a multi-tasking mechanism to execute applications in a concurrent manner.

1.2.2 Microkernel combined with extension modules to achieve universality and configurability

In order to adapt to different "embedded" applications in terms of structure and function, embedded real-time operating systems usually adopt an architecture that combines a microkernel with configurable functional modules, making the operation both universal and configurable. The structure of an embedded real-time operating system is shown in Figure 2. 1.2.3 The operating system does not make assumptions about peripherals

The implementation of the operating system is only related to the CPU, and does not assume other physical hardware outside the CPU. Hardware-related functions rely on another software layer called the Board Support Package to complete, thus achieving the "hardware independence" of the operating system and improving the versatility and portability of the system.

Among them, 2 and 3, as key technologies of embedded real-time operating systems, have strongly promoted the widespread application of embedded systems.

1.3 Comparison between Embedded Real-Time Systems and General-Purpose Computer Systems

The comparison between embedded real-time systems and general-purpose computers is shown in Table 1. Through the comparison, it can be seen that embedded systems are application-centric, based on computer technology, with tailorable software and hardware, adapted to application systems, and with strict requirements on functions, reliability, cost, size, and power consumption. Table 1 Comparison between embedded real-time systems and general-purpose computer systems 2 Implementation of embedded real-time systems

Designing and implementing an embedded real-time system requires not only the design of the application program, but also many key issues such as the implementation of the hardware environment and the selection of the operating system.

2.1 Selecting a suitable embedded real-time operating system

Embedded real-time operating system is the core of implementing embedded real-time system. The performance of operating system directly affects the real-time performance of the whole system to a large extent. Therefore, choosing a suitable embedded real-time operating system is crucial to realize a high-performance embedded system.

2.2 Carefully divide the tasks within the application

As another important software layer, the division of tasks within the application also affects the overall performance of the embedded real-time system. In order to take into account the concurrency and overall throughput of the embedded real-time system, the division of tasks should follow the following principles:

Functionally independent operations should be a single task;

Operations with close functional connections (close coupling) should be grouped into the same task;

Functions with slow I/O operations should be divided into separate tasks;

Different priority operations are divided into different tasks;

· Operations that are computationally intensive should be divided into a separate task.

2.3 Debugging of Embedded Real-Time Systems

Unlike the design of general-purpose computer systems, the design of embedded real-time systems always involves hardware factors, so debugging the hardware platform is a necessary step. In terms of software, since embedded real-time systems are usually multi-tasking systems with strong dynamics, the functional behavior of the system needs to be determined through debugging. [page]

3 Application of embedded real-time systems in communication systems

As a special type of computer system, the application scope of embedded real-time system has expanded to many fields, especially in the field of communication, which has achieved unprecedented development. With the opening of new network services and the increase of new equipment, telecommunication network management has become an increasingly prominent issue and has attracted much attention.

The development of Telecommunication Management Network (TMN) has put forward new requirements for networks and equipment. The earlier equipment and network functions were simple and lacked the necessary and unified management interface, making it difficult for different equipment from different manufacturers to achieve intercommunication and mutual management. To solve this problem, ITU-T has carried out network management standardization work, and has successively formulated a series of protocol specifications to define the architecture and unified interface of network management. Now, when different equipment manufacturers develop communication equipment, they usually parameterize and implement ITU-T's protocols and interfaces for network management. Since ITU-T's network management model involves more layers and more complex interfaces, the functions of network management are much more complicated than before. As an important aspect of network management, equipment management directly affects the overall performance of network management; therefore, networks and equipment with simple functions cannot meet the needs of the development of modern communication networks.

The expansion of communication networks, the massive increase in new services and new equipment require network management to have not only rich management functions, but also good management performance and efficiency; that is, network management must meet certain real-time requirements. In short, modern network management has the following two outstanding characteristics:

·Complete management functions;

Good management performance.

In order to achieve perfect and efficient network management, communication equipment must enhance its own performance, thus providing a high-performance software and hardware platform for high-level network management. Therefore, a new development trend has emerged in the design of communication systems, as shown in Figure 3. The main reasons for this trend are:

(1) The previous method of using microcontrollers as a platform and running applications directly on the CPU has obvious shortcomings:

Limited hardware capabilities, unable to perform efficient and complex device management;

The hardware platform is simple and cannot effectively support multi-functional and complex network management;

The software lacks support from the operating system, and the network application design is complex, making it difficult to achieve full-featured performance network management.

It can be seen that devices based on the single-chip microcomputer platform are difficult to meet the requirements of modern network management in both hardware and software aspects.

(2) General-purpose computers are not suitable for this application environment due to limitations in size, cost, and efficiency.

(3) Using embedded real-time systems is an ideal solution:

Embedded real-time systems use compact and efficient CPUs in hardware, which are suitable for "embedding" inside devices as the hardware core of control and can support complex device management;

In terms of software, the embedded real-time system is based on a high-performance embedded real-time operating system, which not only provides good real-time guarantee for the system, but also simplifies the design of high-level application programs.

With the embedded real-time system as the core, the device has a powerful and efficient software and hardware platform similar to a general-purpose computer system; it not only meets the requirements of network management functions, but also ensures the efficiency of network management; it not only supports the management of the device itself, but also supports efficient and unified network management. Therefore, using the embedded real-time system as the functional core of the device and the network management platform is a widely used implementation solution in current communication systems.

Due to its irreplaceable advantages in functions, performance and price, embedded systems have been deeply and widely used in mobile communications, personal communications, data communications, satellite communications and information appliances.

As a new field of computer application, embedded real-time system has attracted more and more attention due to its simplicity and high efficiency. Since embedded real-time system is different from general computer system, there are several key problems in design and implementation that are different from general computer system. With the increasing complexity of application environment and more and more functions required by the system, embedded real-time operating system has become an essential part of implementing embedded real-time system.

After the development in recent years, the application scope of embedded real-time systems has expanded to the fields that were previously only available for general-purpose computer systems, and the number of applications has exceeded that of general-purpose computer systems, especially in the fields of telecommunications and IT, where they have been used more widely than ever before.

The rapid rise of embedded real-time systems marks the arrival of the "Post-PC Era". Embedded systems are becoming the systems with the most development potential and application prospects after PCs. Their rapid development is becoming a new and powerful driving force for the rapid development of industries such as IT (including communications and information).