Design and Realization of WCDMA Project Simulation System

Transcription

1 Design and Realization of WCDMA Project Simulation System Yehui Liu and Huaiqun Wang Beijing Polytechnic College, Beijing China Abstract. WCDMA is the most widely used standard of 3rd-generation (3G) mobile communication in the world. The construction of WCDMA wireless network is complex. In order to meet the needs of the network construction in China, as well as the simulation teaching of Communication Profession in college, we designed and developed the software, WCDMA Project Simulation System. The software uses geographic information technologies and raster algorithm, and analyses the main processes of wireless network construction, stimulating the key processes such as site location selection, coverage planning, and capacity planning and so on. This software can not only assist the network planning engineers in their works, but also be used in teaching of Communication Profession in a clear way, so it is with a high practical value. Keywords: WCDMA, Simulation system, 3G. 1 Problem The third-generation mobile communication technology (3G) currently has three standards, namely the WCDMA (Wideband Code Division Multiple Access), CDMA2000 (Code Division Multiple Access 2000), TD-SCDMA (Time Division- Synchronous Code Division Multiple Access). Among them, WCDMA, formulated by 3GPP, is a 3G mobile communication system standard based on GSM MAP core network and taking UTRAN (UMTS Terrestrial Radio Access Network) as wireless interface. It is the most widely used international 3G standard, accounting for more than 80 percent of global market share. The construction of WCDMA wireless network is complex. Generally speaking, the construction of a wireless network consists of three main steps: capacity planning, quality planning and coverage planning; link analysis and network planning and design; interference analysis and optimization. In the teaching process of Communications Profession, it is difficult to clearly tell the trainees the complete process of system design by simply using teaching materials, but if you can take advantage of the system project simulation software, you can not only reasonably and orderly display the various complex devices and parameters in the intangible and invisible network, but also lively show a lot of invisible concepts and freely change the virtual devices and the environment on the site, thus greatly enhancing teaching effectiveness. Therefore, developing a set of WCDMA system project simulation Z. Du (Ed.): Intelligence Computation and Evolutionary Computation, AISC 180, pp springerlink.com Springer-Verlag Berlin Heidelberg 2013

2 462 Y. Liu and H. Wang software and applying it in the teaching and training of Communication Profession at a low-cost and low-risk way is of great practical significance and application prospects, and also plays a guiding role in live WCDMA system project practice. 2 Structure and Function of the Simulation System In order to comprehensively simulate the construction process of wireless network, the WCDMA system simulation software is divided into five independent functional modules, namely network planning, computer room construction, device operation, signaling process analysis, and network optimization. In the network construction process, key steps such as base station site location selection, coverage and capacity planning, network basic topology definition, network element design and connection configuration, antenna feeder system selection, signaling analysis simulation, and drive test optimization are allocated in the five modules in accordance with the project progress, as shown in Figure 1: Fig. 1. Software function structure chart 3 Software Key Technologies Geographic information technology (GIS) is a core technology of this software. The targets processed and managed by GIS are data of a variety of geospatial entities and their relationships, including spatial location data, graphic data and attribute data, etc, which are used to analyze and handle various phenomena and processes distributed in a certain geographic area. During the base station site location selection, the network base station data (including cell data) has become part of the geographical environment due to its relatively fixed location, so it can be seen as a point feature in the geographical environment. Therefore, geospatial information of the base station can be stored in the form of point geometry, and non-spatial attributes of the base station can be attached with graphics via the base station ID.

3 Design and Realization of WCDMA Project Simulation System 463 During coverage planning, the signal strength distribution data can be regarded as continuous coverage in a certain area, and signal strength distribution data can be accessed by Raster in geographic information, and easily be retrieved and queried, as well as be displayed in the form of image.. During wireless network planning, the planning function is to calculate the coverage of the planning area by using wireless signal communication models. The communication models can be divided into outdoor communication model and the indoor communication model by applicable environment; and empirical model and deterministic model by source of the communication model. Through the analysis of the communication environments, previous researchers and engineers have put forward a number of communication models to predict median field strength of signals accepted. Currently, widely used communication models include Okumurahata model, COST321 Hata model and general models. The communication model used by the system is a universal model, whose coefficient is derived by Hata formula. The general model is determined by the following equation: Path_Loss=K1+K2*log(d)+K3*(Hmeff)+K4*log(Hmeff)+K5*log(Heff)+K6*log( Heff)*log(d)+K7*(Diffraction_Loss)+Clutter_Loss The meaning of the parameters in the formula is explained as follows: Path_Loss: communication path loss (db) K1: attenuation constant K2: distance attenuation coefficient K3, K4: mobile station antenna height correction factor K5, K6: base station antenna height correction factor K7: diffraction correction factor Diffraction_Loss: diffraction loss Clutter_Loss: surface features attenuation correction value d: the base station and mobile station distance (km) Hmeff: mobile station effective antenna height (m) Heff: base station effective antenna height (m) For the simulation of phenomena with continuous distribution in a certain space like signal strength, field based view is appropriate. Field model can be expressed as the following mathematical formula: z : s z ( s ) Where, z is a measurable function, and s represents the position in space. In this system, Formula: signal strength = sector power + antenna gain - path attenuation, that is, measurable function. The system uses a raster method to calculate the signal strength, in which raster data model is based on a continuous coverage, and it discretizes a continuous space and covers the entire contiguous space with two-dimensional coverage or division.

4 464 Y. Liu and H. Wang 4 Software Functional Modules The WCDMA project simulation system manages wireless network construction and simulation teaching through eight main modules. The eight modules are planning principle, planning and design, network construction, RNC board operation, NodeB maintenance, RNC maintenance, signaling tracking, and network optimization. Network planning module includes the description of planning principles and planning simulation, of which the description of planning principles designs an interactive multimedia teaching framework according to WCDM planning principle. Trainees can independently design the steps of the whole planning principle process based on their understanding and mastery of WCDMA planning principles. The system automatically determines whether every step of the process is correct or not, and guides trainees into the next process based on the results and commence the introduction to the process. All the processes are correct, the system will automatically generate a network planning report. The effect of the description of planning principles is shown in Figure 2. Fig. 2. Operation of Planning Principles module Planning simulation part provides the virtual geographical environment of the designated areas, and allows trainees to conduct base station site location selection and capacity planning in a virtual geographic environment, set the parameters of the base station sector and simulates coverage planning for the set base station data. The effect of planning simulation part is shown in Figure 3. Fig. 3. Coverage planning results

5 Design and Realization of WCDMA Project Simulation System 465 The room construction module is mainly used to simulate the process of defining network topology, designing network elements, configuring links and selecting antenna feeder system. It displays the construction of a virtual room in the form of multimedia animation, and the above-mentioned simulation, trainees are allowed to conduct independent operations, and test whether their independent operations are correct according to the results of the network planning. The effect of the room building part is shown in Figure 4. Fig. 4. Simulation of room building 5 Summary and Outlook WCDMA project simulation system, relying on geographic information technology, decomposes engineering construction of the entire wireless network into several relatively independent parts that are correlated and echo each other and form an integral system. The system simulates important links of network optimization, network regulation, and signaling tracking, and can truly reproduce the scenarios of network optimization and network regulation, so that it can both help network optimization engineers work in real practices, and be used in teaching of wireless communication profession in an intuitive way, thus having a high practical value. The system has been used in the experimental program of the communication vocational education, and achieved good results. How to further strengthen and improve the simulation capabilities of the system to make the simulation more realistic is the direction of future improvement and extension. In addition, considering that the current 3G mobile communications systems also include TD-SCDMA and CDMA2000 in addition to WCDMA, and these two standards are equally important in teaching, we will continue to research and develop system engineering simulation software for the two other standards.

6 466 Y. Liu and H. Wang References [1] Zhang, C.: WCDMA Communication Network Planning and Design. People s Posts & Telecom Press, Beijing (2007) [2] Pang, W.: On the Planning of WCDMA Wireless Network. Mobile Communications (1), (2004) [3] Zhou, Y., Zhang, J., Tao, J., Zhang, M.: Exploration of WCDMA Network Capacity Optimization Strategy. IT 31(3) (2007) [4] Bi, M., Wang, S.: How to Balance Coverage and Capacity in WCDMA Network Planning. Design Technology of Posts and Telecommunications (10), (2004)