Abstract: Introduce the UE structure of the TD-SCDMA system and put forward the method of using SDL to develop the TD-SCDMA high-level signaling system based on practical work experience. Keywords: TD-SCDMA system SDL language MSC real-time operating system 1 Introduction to SDL language SDL (Standard Description Language) is widely used to describe the behavior of communication systems. It is the specification description language recommended by CCITT. After the development and standardization of ITU-T, it is defined in Lampi Z. 100 recommendations. ITU-T launched the first official version in 1988, with supplements and updates every four years thereafter. As the official language of international standardization, it is used to standardize the description of real-time multitasking systems. SDL and other related technologies such as Z. 120 suggestions-message sequence diagram and Z. 105 recommendations and abstract grammatical symbols together form a complete description language. In the development process of protocol software, SDL is applied in the system specification description and design stage. It is completely independent of hardware implementation and operating system. The SDL software provided by Telelogic Tau can not only be used for specification description and design, but also can generate standard C code directly from the description and design of SDL. Users can also directly embed C code in the SDL description and design to complete the functions of the implementation part in Figure 1. The C code (including embedded C code) generated by the SDL description can be directly integrated with a variety of embedded (or non-embedded) real-time multitasking operating systems, such as NUCLUS, pSOS, Solaris, Vrtx, and OSE. It can be run directly on the target board, which is convenient for users to develop protocol software. The MSC (Information Sequence Diagram) corresponding to SDL is the language used to represent information sequences in the ITU-T specification. In 1991, ITU-T standardized MSC. The flow of the signal can be conveniently expressed by the MSC diagram, that is, from which process the signal is sent to which process, whether the signal has parameters, specific parameter values, etc. can be visually represented in the SDL MSC diagram, which is for understanding and analysis The transmission of signals between modules brings great convenience. Not only that, the functions of SDL can be organically linked together through the MSC diagram. In the tracking and debugging process of the software, using Simultor and Validator can generate MSC graphs. In the software's TTN test process, MSC charts are often used to analyze the test results. The MSC diagram can also intuitively describe the sequence of signal transmission, which is not possible in the SDL description. The last step of development is to use TTCN for testing. TTCN (Combined Tree and Table Representation) is a standardized test language defined by ISO and ITU in ISO / IEC 9646-3 The system designed with SDL is a hierarchical structure system, which includes the system, function blocks and processes. A system can contain multiple blocks, and each block can consist of one or more processes. The process is the smallest processing unit in the SDL system. It is described by EFSM. All users' processing and operations are completed in the process. The content (signals, data structures, etc.) defined at the system level can be used in all blocks and processes under the system, and the content defined under the block can be used in any process of the block. It is these characteristics of SDL that play an incomparable role in the development of protocol software. The following uses SDL to develop TD-SCDMA high-level signaling to briefly explain the use of SDL. 2 TD-SCDMA system structure First introduce the structure of TD-SCDMA system. According to the requirements of the TSM protocol and the needs of actual product development, the TD-SCDMA system user terminal protocol software can be divided into the system structure shown in Figure 2 (excluding the packet data service part). The whole system structure satisfies the layered structure of TSM protocol. At the same time, TSR and HL1 modules are added according to the needs of control and software. It is a SDL block-level TD-SCDMA high-end signaling structure of UE. There are six modules in the whole system, each module corresponds to a block in SDL, and each module performs different functions. The following briefly introduces the function and interface of each module. The CM module completes connection management functions, including call control, short message, and additional services, namely the CM block in Figure 2. The MM module completes the mobility management function in the circuit-switched mode, and realizes the mobility, security, and connection management of the UE, namely the MM block in FIG. 2. The TSR module is a signal relay module, which is a part of the MM sublayer, which mainly realizes the function of signal routing; at the same time, based on the multi-instance (such as the establishment of multiple calls) of the entities in the CM sublayer, the CM module is managed by multiple instances . The RRM module completes wireless resource management and control functions. In idle mode, the RRM module performs cell selection and cell reselection, initiates RR connection establishment and handover in response to network paging or high-level RR establishment requests; during the RR connection establishment process, the RRM controls the HL1 module to initiate immediate assignment Process, the establishment of the main signaling link; in the connection mode, RRM mainly completes the resource management of the connection mode, such as assignment, channel mode change, and switching control processes; processing associated signaling, such as analyzing and processing system information types 5. Type 6: sending measurement reports and analyzing and processing layer 3 messages received on the FACH channel. In addition, the RRM module also controls the process of measuring the serving cell and neighboring cells by the HL1 module. The DL module completes the wireless connection control function, which mainly includes: providing one or more data link connections on the channel, different connections are distinguished by the data link connection identification DLCI; providing a frame type identification mechanism; allowing layer 3 messages in two Transparent transmission between layer 3 peer entities; sequence control to maintain the sequence of frames connected by a data link; with format and operability error detection function on the data link; when a data link becomes unavailable When recovering from errors, it has a mechanism to report errors to the layer 3 entity; it has the function of flow control; after completing the access request on the RACH, it has the function of resolving conflicts when a data link needs to be established. The HL1 module is a bridge connecting the protocol layer and the physical layer. According to the hardware design of the system, the tasks of the protocol layer and the application layer are completed by the ARM processor. The DSP processor is responsible for completing the specific physical layer bottom tasks, such as source and channel codec, interleaving, measurement of various physical layer parameters, Spread spectrum and modulation. The two processors exchange data through interrupts. Based on the request of the protocol layer, HL1 schedules and controls the physical layer resources by decomposing and planning the tasks of the protocol layer. Mainly include: In the process of cell selection, the HL1 module controls the physical layer to measure the code power of the neighboring cell, interpret the BSIC, interpret the phase of the DWPTS, read the BCHCH block and other tasks; in the idle state, the HL1 module controls the physical layer to perform services The measurement of the cell and neighboring cells, interpret the system information of the serving cell and the system information type 1 of the strongest 6 neighboring cells, and report the measurement results and the read system information to the RRM module; during the random access process, according to the RRM The control signal of the module, the HL1 module controls and schedules the physical layer to perform the random access process of message transmission and reception; in the connected mode, the HL1 controls the physical layer to perform data transmission and reception, service and neighboring cell measurement, and handover process. 3 Development of TD-SCDMA method using SDL system In the description of the TD-SCDMA system in Figure 2, you can use Telelogic Tau AB's SDL Editor to describe it as a standard SDL description form. But not all parts of the system can be developed using SDL. The C language (or other languages) is required to complete the hardware driver, the specific algorithm of the physical layer, the encoding and decoding of the channel, and the operation of the SIM card. Finally, all the code is compiled into an executable target code. The specific process is shown in Figure 3. The system development code running platform is ARM, and the operating system is NUCLUS PLUS. The use of SDL to implement TD-SCDMA high-level signaling software process is as follows: The first step: first define all the data structures according to the description of the detailed report. For example, the structure of saving system information, IMSI code structure, TMSI code and task planning and other structural definitions, these data structures can be in C / C ++ language format or ANS. 1 format is completed, they can be used by SDL. C / C ++ describes the CP2SDL that can be provided by SDL. The EXE tool is very easy to convert to SDL, and the PR text can be used directly [8]. The second step: use the SDL tool to compile the TD-SCDMA system description and the relevant PR description completed in Figure 2, and compile them into different C / C ++ codes as needed. The running code? The hole is usually selected in Cadvanced mode? Snow, the other is the code that can be provided to TCN test. The third step: Because the generated target code and test code have good consistency, the use of TTCN can check out the problems in the SDL design to ensure the correctness of the SDL design. This is also one of the advantages of using SDL for TD-SCDMA system development. According to the test examples written in the TSM 11 (TD-SCDMA System Test Specification) series, it is convenient to carry out the protocol conformance test and find the problems that occur in the development as much as possible, avoiding these errors to be brought to the board-level debugging, thereby speeding up Software development speed. Step 4: The C source code generated by the SDL description needs to run on the ARM hardware system, and also needs to be integrated with the selected RTOS operating system. SDL can be integrated with multiple RTOS systems, and their integration principles are the same. According to the process task of SDL, the processing situation in the RTOS system can be divided into two types, one is deep integration and the other is light integration. They have the same effect, the difference is that deep integration processes each process in the SDL description as a process in RTOS, while light integration processes the entire SDL system as a RTOS process. In practical applications, the second method is mostly used. This method is convenient for the integration of SDL and RTOS systems, and only needs to modify the interface file setnv of SDL during integration. c. In the interface file, add the following NUCLEUS function: NU_Creat_Memory_Pool () NU_Allocate_Memory () NU_Creat_Task () The first two functions are used by NUCLEUS to allocate memory and save the SDL process control block. The NU_Creat_Task () function is used to create the task of NUCLEUS, which is the key function of the interface between the SDL process and NUCLEUS. The function has 11 parameters: Task_Ptr, "SDL_fn", SDL_main, 0, NULL, Stick_Ptr, MANAGER_STACK_SZEZE, MANAGER_ TASK_PRIORITY, MANAGER_TIME_SLICE, NU_PREEMPT, NU_STRAT; where Task_Prt is the control block that points to the process, "SDL_fn" is the name of the process, Stick_Ptr is the stack pointer of the process, MANAGER_STACK_SIZE is the size of the stack; MANAGER_TIME_ SLICE is the maximum time that a process can occupy (calculated in ticks). The modified interface function only needs to be compiled with the source code generated by the SDL and the code provided by the operating system. Each time the system is started, NUCLEUS treats the SDL description as an independent task. The SDL process is managed by the SDL kernel, and the entire SDL system is managed by NCULEUS. The NUCLEUS system has its own complete message processing mechanism, and the code generated by the SDL also has its own signal processing mechanism. They are independent of each other and work together to form an application system [9]. Finally, the code generated by SDL, the code of NUCLEES and the hardware driver written are unified into ARM running code. In the entire software development process, the actual development process is not so simple from the first step to the fourth step, sometimes they are intertwined. The problems found in the test of TTCN and the target board are fed back to the design process, and are constantly revised until the system is finally perfected. It can be seen from the above process description that SDL has the following advantages: (1) The SDL tool can support both graphics (GR) and text description (PR), and can be converted to each other. The graphic method is convenient for designers to intuitively understand the design results, while the text method is easy to save. (2) Facilitate software design. The detailed design report and code design process can be organically combined. SDL can directly generate the required code by using the detailed report part described by SDL. (3) Because SDL has consistent target source code and test code, it can be directly tested by TTCN, which greatly improves the accuracy of the source code designed by SDL. At the same time, SDL has a rich MSC interface. During the testing of Valator, Simultor, and TTCN, there are MSC output, which can provide designers to check the problems in the design. The code generated by the SDL can be run on a variety of real-time multitasking platforms, and can be easily integrated with RTOS systems such as pSOS, Nucleus Plus, Solaris, VxWorks, OSEDELTA, etc., and has good consistency. The SDL tool can integrate the entire software development process, requirements report, overall design report, detailed design report, code design, and testing and maintenance. The design of each part can be described using the different functions of SDL, saving manpower and material resources to the greatest extent. However, SDL is not omnipotent in the development of protocol software. Although the description of SDL is intuitive and convenient, the code generated by SDL is very complex and not easy to modify and read. This is also the only concern for SDL. Usually a humble BUG in the generated code will never be found. |
, Is the third part of ISO / IEC 9646 standard, used for the test notation of the OSI conformance test set. The tree-table combination notation, as the name implies, is to use the test notation in the form of a tree and a table. The table is mainly used for data types, primitives, protocol observation points, constraints, etc., and the tree is used to describe the test set and test. Examples, test steps. It is very important to verify the validity of standards and conformance testing of communication software. 
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