Develop the structure of small Switching System in Vietnam

Transcription

1 Develop the structure of small Switching System in Vietnam Phát triển cấu trúc hệ thống tổng đài nhỏ ở Việt Nam Hoang Minh Tóm tắt: HiÖn nay, ph t trión phçn mòm îc coi lµ c héi míi cho c c ngµnh c«ng nghiöp ViÖt nam. ý t ëng ph t trión nòn c«ng nghiöp BCVT trong n íc (bao gåm c hö thèng tæng µi dung l îng nhá) sö dông c c phçn cøng tiªu chuèn quèc tõ nh b n thµnh phèm, thiõt kõ cêu tróc hö thèng vµ lµm chñ phçn mòm b»ng nguån lùc trong n íc ra êi. Bµi b o nµy tr nh bµy ng¾n gän vò cêu tróc m¹ng VNPT vµ chiõn l îc cña VNPT ph t trión c c hö thèng tæng µi. PhÇn cuèi cïng cña bµi b o sï giíi thiöu vò ph ng ph p luën vµ c c kõt qu cña dù n VINEX dù n ph t trión tæng µi 1000 sè. I. VNPT s existing Telecommunication Network Architecture 1.1 General Information Until now, Vietnam Post & Telecommunications (VNPT) share has been estimated by 90% in domestic market [1] and VNPT is the only Service Provider has a license to do International Telecommunication Services. In recent years, VNPT Telecommuni-cation Network has been improved rapidly on both sides: Size of network and Technologies & Services. Size of Network: According to the Post and Telecommunication newspaper (published on Feb. 2001), at middle of March, VNPT Telecommunication Network will have 3,500,000 subscribers. The biggest city of Vietnam- Ho Chi Minh Ville, has a teledensity of 18-lines/100 inhabitants, while national figure of 4.27 lines/100 inhabitants [1], and VNPT schedules to archive the number of telephone lines as: 4,183,000 by which increasing the national teledensity of 5 lines/100 inhabitants [1] by the end of Technology: Transmission technology is changing from PDH to SDH with 100% Provinces has a Province Optical Backbone based on SDH technology [2]. New Services: Various of new services have been given in the recent years, and plan to provide new services in the market from the year of 2001, basing on ISDN, IP, and ATM. Mobile Services are also focused [2].

2 Signaling Network: VNPT are using both of signaling system in theirs network: R2 and SS7. In the near future, VNPT planes to change R2 signaling all to SS7 signaling network[2]. 1.2 Switching Systems network International Gateway VNPT used AXE-105 system at: Hanoi, Danang and Ho Chi Minh Ville as 3 International Gateway [2]. Toll: VNPT divides theirs Country Network into 3 layers: Toll/Tandem Layer: 03 AXE-10 Switching System (located at Hanoi, HoChiMinh, Danang) and 02 TDX-10 (Located at Hanoi, Ho Chi Minh). Basing on these systems, VNPT used as Local Tandem Systems [2]. Province Layer: Including 124 HOST Switching System. These Systems are located in 61 Provinces. Totally, this layer consist various kind of Switching System [2]. (AXE-10, TDX-1B, E-10 EWSD..) District Layer: Consist a lot of Stand-Alone Switching System and also remote systems of HOST System. There are more than 10 kind of Stand-alone Switching system is still operating on the Network. 1.3 Transmission Systems Network International Link VNPT are using the both: Cable-Marine and Satellite Systems [2]. Country Link SDH Technology based on Optic-cable Network VNPT has implemented SDH technology Equipment form Foreigner Venders such as: Nortel, Siemens, Fujitsu. The bandwidth is 622Mb/s and 2.5 Gb/s [2] PDH technology based on Microwave Network

3 VNPT has implemented many Equipment form Foreigner Vendor such as: Alcatel, Siemens, Marconi, Fijitsu, Summary: VNPT Telecommunication Network is fully digital Network but it is complicated Network because of basing on many kind of network Element. Because of this character, VNPT has an advantage such as they cannot be control by Foreign Venders. But they also get many disadvantages such as: To difficult to manage and maintain they Network II. VNPT s Strategy for development of Switching System in Vietnam 2.1 General Review With the plan to reach the teledensity by 8 lines/100 citizens in 2005, VNPT should invest 3.5 million subscribers in the next 4 years. However, to deploy this plan, VNPT cannot implement 100% equipments in theirs Network by importing Equipment because of many reasons, one of those is that VNPT should follow Government guidance on the strategy of development Domestic industry. In Vietnam, up to 80% of population are located in rural areas but used only 8% of Telecommunication services. VNPT determine the rural is potential future market and planning to provide their services in to rural areas, it is a good chance for switching development in Vietnam, especially for small and medium - sized switching systems because of their economy and flexibility Therefore, mastering an open telecommunication system is necessary and urgent... With the capability of Vietnam engineers, to meet the demand, developing and manufacturing small switching systems is greatly significant. 2.2 Difficulty and solution: How to develop Small Switching system in Vietnam? Today, system structure of switching systems has been considering and closely managed. Mastering system structure of switching system, allow us to deploy other functions (operations, management, and maintenance...) as well as reconfigure the system to meet Vietnam network reality [3]. According to the research results about the small switching systems in VNPT Network, we can summary as follow: Imported System: High qualification and reliable. However, these Systems are hardly to match with changes and features of Vietnam Telecommuni-cation

4 Network and not enabling user (operator) to reconfigure the system. And its price is high [3]. Domestic System: There are some kinds of Small Switching systems in VNPT Network, which are researched, developed and manufactured by Local Companies. However, its remain problems are: - Hardware function blocks are domestically manufactured so the stability and safety are not very high. - The open feature of system structure is not proved. A professional operating system has not been applied into the system yet. Man - Machine interface has not met Vietnam Telecommunication network's requirements (especially for rural Telecommunication) [3] Then, the question is: How to develop the Small Switching system for Vietnam? At this time, the Software Development is new chance for Vietnam industries. Vietnamese engineers can design and develop a big and difficult software systems. Therefore, the idea for developing Domestic Telecommunication Industry (including Small Switching system) has been occur: " using international standard hardware products like semi-products, designing system structure and mastering software by domestic resources". III. VINEX The Switching System for Vietnam 3.1 General structure of the switching system Since a switching system is a node in an overall communications network, the architecture of the switch is established from functional requirements of the node. The elements of a circuit switching digital switch is as shown in Figure 1. Terminations are provided by the switch for both analog & digital signal (A and B port correspond).

5 Synchronization Port B Digital Termination Multiplex Translation Switching center network Resources Port A Analog Termination A/D D/A Multiplexer Control I/O Administration and Maintenace Signaling Figure 1. Elemens of a digital switching system The Multiplexer is an element which combines/splits low speed data channels to/from high speed ones. Multiplex translation is needed if the format of terminations is different from the switching center network multiplex format. The switching center network contains space-divided and time-divided switching stages that allow information on any multiplex time slot to be transferred to any other multiplex time slot Various resources are attached to the switching network. These include digitally synthesized tones, conference circuits, tone receivers, and other signalprocessing devices Control of overall system is provided by that stored program controls (SPC) processor accessing to various system elements Input/Output devices are used to provide a variety of system functions including dial administration, alarm reporting, maintenance access, traffic reporting, automatic message accounting, and common channel signaling. 3.2 Develop the VINEX 1000 Structure Vinex 1000 is the name of the development project. VINEX stand for Vietnam Exchange. A special team of PTIT has developed this project form 1997 and this project has been finished at the end of The result of this project is a

6 Switching System named VINEX VINEX 1000 has total 1280 ports (can be expand to 2048 ports) and it is a very flexible configuration. After development, VINEX 1000 has been transferred for industrial factories and they have manufactured VINEX 1000 to supply for VNPT Network. To develop VINEX 1000, the first mission is defining the feature and function of the system. This system should adapt the ITU requirements for Switching system (Switching, Numbering, Routing, Transmission Interfacing, Signaling, Synchronizing, Man-Machine Interface) [7], [8] and also should follow all of requirements of DGPT to adapt Vietnam reality [4], [5], [6]. VINEX are small and medium- sized Switching system, then it can use in District Layer of VNPT Network. Therefore, its technical requirements are higher than small Switching systems (capacity under 1000 ports). It should focus on some specific requirements as following: - 24/24 hours continuous and stable operating - Flexible on re-configuration - Monitoring and managing the status of the System as well as Functional Blocks - Alarming Function - Easy for Operating, Administration and Maintenance - Safety and accuracy on Charging - Remote Management and Upload Vietnam is not capable to develop local telecom industry, so to develop VINEX 1000, we should find the suitable international standard Hardware from foreign vendors to reuse their HW like semi-products. After considering, we chose hardware form VNPT-LGE join Venture (This Join Venture manufacture Big Switching System serve for Province Layer of VNPT Network). We used all of their hardware: Subscriber card, Trunk card, Signaling Card, Control card and after that, we design our system structure and develop all software by ourselves. Base on this solution, we will have a stable and International Standard platform because we have used the industrial products resulted from advanced industries and technologies [9],[10], [11]. VINEX has a distributed structure [13]. The control Structure is showed in the Figure 2. In the Main processing layer (MPM), we applied hoststandby technique and 2 MPM are running parallel. They send message to each other through a common buffer (Share RAM) basing real-time control

7 signaling [13]. On this, we used a Real-Time and Multi tasking OS (This are based on Motorola CPU MC 68020) [12]. Application Processing Man-Machine Interface Main processing Switching Inter Processing Control Control Signals Generation Subscribers Control Trunk Interface RMFC Receiver/ Transceiver DTMF Receiver/ Subscriber Cards 1. Control Bus 2. Signaling Bus Figure 2: Vinex 1000 Control Path Structure The Figure 3 describes how speech path is designed on the VINEX The speech path on Vinex 1000 including voice path and message path basing on PCM links. We used 4 sub-highway (2048) as IPCM link to transfer message between s [13]. The figure 4 shows I/O functions of VINEX To make easy for maintenance and management, all of Functional Blocks has their own I/O port. For the system, we put one Floppy disk 3.5 and one hard disk in to the Application Processing with the purpose is store and manage all of Application data, Operating data, Traffic data, File log and Alarm messages (Not system data) [13].

8 Application Processing Man-Machine Interface Main processing Switching Inter Processing Control Control Signals Generation Subscribers Control Trunk Interface RMFC Receiver/ Transceiver DTMF Receiver/ Subscriber Cards 4. Control Bus 5. Signaling Bus Figure 3: Vinex 1000 Speech Path Structure

9 Tone Clock Application Processing Main Processing RS 232 Digital Switch Matrix Array InterProcessing Control Trunk Line card RMFC DTMF Univesal Line Processing Subscriber Line card RS 232 RS 232 RS 232 Figure 4: Vinex 1000 I/O Interface and Functional Block Structure I. Conclusion The object is successfully developed so as to prove the creativeness and open a way to develop Domestic Telecommunication industry that is" using international standard hardware products like semi-products, designing system structure and mastering software by domestic resources". Base on this solution, Vietnam can speedily developing local informatics capability and telecommunication capability with the lowest investment of time and expenditure. References: 1. Post and Telecommunication Magazine (Vietnam) Vol. Dec.2000 and Vol. Feb Project: Built up the Network Management Center for VNPT Oct.2000

10 3. Hoang Minh. Research results of the project: research and development small switching system with capacity lines ( KHKT-RD and TCT-P) 4. Directorate General of Posts and Telecommunications DGPT-Technical Standardization Specification for Small Switching System. TCN DGPT-Climate Standardization Specification for Telecommunication Equipment. TCN DGPT-Technical Standardization Specification for PABX System. TCN TELSTRA. INTER-Exchange signaling Systems for Vietnam; CCITT. Interworking of Signaling Systems LGIC. STAREX VK 10. LGIC. STAREX APR General Descriptions 11. LGIC. STAREX Ldi General Descriptions 12. Stuart Bennett. Real Time Computer Control t Hoang Minh. Research results of the project: research and development switching system with capacity lines ( TCT-P) Author Biography: HOANG MINH - Year of birth: : graduated from Hanoi University : Working in the Research Institute of Post and Telecommunication (PTIT Member) : Working in the Company for Development of Information Technology (CDIT PTIT Member) as director - He is now carrying out the PhD. thesis on Research and develop structure of small switching systems adapted with Vietnam network