Advantages of 3G protocol standards

We know that the current 3G protocol standards include TD-SCDMA, CDMA 2000 and WCDMA. Here, we will not summarize the features and differences of the three protocols, but mainly discuss some advantages of the 3G protocol standard. Let's take a look at the specific applications and functions it contains.

1.3G protocol standard

TD-SCDMA and UMTS/IMT-2000 systems will be widely used in the next few years. The following formal languages are part of the 3GPP method and are widely used in standards:

SDL, Specification and Description Language, Specification and Description Language, graphical Language used to describe the system structure and behavior ｡

MSC, Message Sequence Chart, Message Sequence Chart, and graphical language that describes the communication Sequence ｡

ASN.1, Abstract Syntax Notation Number One, Abstract Syntax Notation 1, describes protocol information and CODEC language ｡

TTCN, Tree and Tabular Combined Notation. The Tree table describes the language of consistency testing in combination with the Notation ｡

All these languages are standardized by ITU and/or ISO. They can be processed by computers, there are already excellent integrated development tools in the market. Below we discuss the advantages of using formal language for TD-SCDMA and UMTS protocol stack development ｡

2. Quick Start

The advantage of using the 3G protocol standard to implement the Protocols described by SDL and ASN.1 Based on the SDL/ASN.1 tool is obvious. The user starts to develop the specifications that can be processed by the computer. This specification is completely correct -- because it is a standard ｡

The TD-SCDMA and UMTS standards contain a complete, detailed description of the protocol data units (PDUS) used in the Protocol. When ASN.1 is used in the standard, ASN.1 can and should be used directly in the implementation process. In the 3G protocol standard, ASN.1 has been detailed to automatically generate the decoder, which can be directly used as the implementation language for data definition ｡

However, the SDL specification in the standard is far from detailed enough to generate an implementation directly. Some behaviors are described by state machines, but limited to behaviors that directly affect the external features of the protocol entity, this is also an abstract method that does not limit the implementation of the Protocol. Many semantic descriptions of the standard are sometimes represented in SDL images in additional texts as non-defined processes ｡

To obtain an executable specification, the implementer must add a Protocol framework to create, manage, and delete protocol entities. In addition, many architecture options, such as the buffer mechanism, must also be determined, all semantics of the standard are represented by the behavior diagram and external process (which must be implemented). The SDL is initially described from the standard and then goes through several more implementation-oriented follow-up stages, until it is implemented ｡

The advantage is that SDL/ASN.1-based implementers do not need to create a system description from scratch because they already have a starting point in the standard ｡

3. Early verification and Verification

The second major advantage of the 3G protocol standard is that practitioners do not have to wait until the complete implementation to observe and test behavior. Even very limited SDL descriptions can be simulated. one way is to compare the MSC diagram in the standard with the MSC diagram generated in the simulation ｡

In addition, by observing the simulation description behavior and providing specific input, the implementers can also enhance their understanding of the Protocol ｡

4. mature methods

From TD-SCDMA or UMTS standards to implementation is a very complex task. To control this complexity, it is very important to develop in stages, limited, well-defined, and easy-to-understand enhancements at each stage. This method not only facilitates the development process, but also makes the choice of systems and structures more visible and visible, it can also be publicly discussed and improved without hiding behind and hiding behind the complexity, and invisible to others except the real-world ｡

In this sense, the SDL-based approach is mature. This traceable and reproducible process already has existing courses, books, and consulting services ｡