Miniaturization technology of SDH multi-service access equipment

Abstract: This paperanalyzesthe demand for miniaturization of access system brought about by the marginalization ofSDHtechnology application in view ofthe development trend that SDH is gradually applied to multi-service access at the end of the communication network and the user side,proposes toadopt the miniaturization design in the research and development ofSDHmulti-service access equipment, and at the same time discusses the problems and countermeasures faced in the overall implementation scheme, multi-service integration, system structure and interconnection, simplification of upper and lower service interfaces, component selection and reduction of design power consumption. At the same time, it discusses the overall implementation scheme, multi-service integration, system structure and interconnection, simplification of upper and lower service interfaces, component selection and reduction of design power consumption, etc., andits countermeasures.

Keywords: SDH , access network, multi-service, miniaturization design

I. INTRODUCTION

The application ofSDHin China has been very mature,SDHtechnology is currently being extended to the edge of the network and multi-service access layer, has become a development trend of the fiber optic access market.SDHtechnology has the reliability, flexibility, and provide multi-service access capabilities of thelaunch of theSDH/MSTPplatform allows network operators to quickly and efficiently meet the needs of users of a variety of service access,SDH's This advantage makes it gradually expand its application to the field of access network, and its functions and interfaces are constantly close to the end user. Therefore,the marginalization of the application ofSDHtechnology on the equipment size, cost, reliability and other aspects of the new requirements, many applications (such asFTTB,FTTC,OLT/" target="_blank">FTTH, etc.) requireSDHaccess equipment as miniaturized as possible, which is moreintegratedthan the traditionalSDHequipment, compact, and can be placed on the desktop, fixed to a wall or placed in a standard machine. wall or placed in a standard cabinet. Currently, many equipment developers in the industry are trying to makeSDHsmaller and more sophisticated, while meeting the needs of more services.

II. Miniaturization design features

Miniaturization of electronic products should generally follow the following principles: without affecting the function of the case, through the miniaturization of the product as much as possible to save the use of resources, such as the use of small devices, the removal of redundant functions; simplify the product structure, advocate the "simple and beautiful" design principles, such as reducing the number of product components, etc.,the use of modularized structural design and easy to disassemble the linkage, and minimize the number of fasteners; in order to ensure the durability of the product on the basis of giving the product a reasonable service life, and at the same time, consider reducing the energy consumption in the process of using the product, and so on. Therefore, in the specific design, it is necessary to consider the product design area, the thickness of the devices used, working efficiency, system heat dissipation, system reliability and other factors.

With the continuous progress of information and electronics technology and chip, manufacturing process continues to mature, miniaturized design has been widely used in consumer information products. Nowadays,the marginalization of the application of SDH technology makesthe SDHaccess equipment to provide a variety of services and reduce the cost of development at the same time, is gradually converging to miniaturization.

III. SDH multi-service access equipment miniaturization design

In the field of low-end optical transmission and access equipment, PDH optical terminals and optical cats and other fiber optic transmission and access products, due to relatively simple in the realization of the technology, the business capacity of the equipment is not large, many equipment manufacturers have adopted miniaturization technology to reduce equipment costs, reduce power consumption and reduce the volume, for operators to save the number of racks, reduce the server room occupies the purpose. However,the mapping and rewiring ofSDHaccess equipment is relatively complex, and traditional solutions require a set of integrated circuit chipsets to complete. For example, through the traditional program to design a set of simple dual-optical port155M ADMequipment, many manufacturers have chosen to usespecial integrated circuitssuch asPMC.The simplest device also requirestwoline interface chips,twoTUPPchips, in addition to the need for a dedicated clock chip, as well as the appropriateMAPPERchip and so on. Only these integrated circuits discharged on thePCBwill take up a lot of space, plus optical modules, up and down the2Mcircuit port, network management interfaces, etc., the volume of equipment is often made relatively large.

However, the high-speed development of computers and ultra-large-scale integrated circuits and other technologies for the SDH highly integrated, highly flexible to provide the possibility of realization. In recent years, China's government has increased support for the software and integrated circuit industry. Compared with the developed countries of China's integrated circuit industry started relatively late, which has been themain bottleneckrestrictingthe rapid development ofChina'sSDH, but also because we started late can learn from the success of foreign experience and lessons learned, to make up for the shortcomings, so that we will be able to take less detours, we designed the product in the overall planning, integration, and so on, in many aspects can be compared with foreign products have made greater progress. At present, China's rapid development of integrated circuit enterprises, some manufacturers have begun to work onthe application ofhighly integrated special-purpose integrated circuits inthe field ofSDHaccess equipment to promotethe development of miniaturization technology forSDHaccess equipment, and made an important contribution; there are also a number of equipment manufacturers are using low-pricedFPGAfield-programmable logic devices to achieve simpleSDHaccess equipment. We believe that the current market outlook for metro optical networks and access networks in China is promising, and miniaturizedSDHaccess devicesfor use at the edge of the networkwill also grow rapidly. Therefore, wehave adopted the miniaturization design conceptin the newly developedTOPAccesslow-costSDHmulti-service access equipment to reduce the size and area of the motherboard as much as possible under the premise of satisfying the flexible configuration of multi-services and striving for concise product design solutions, perfect functionality, low power consumption, and small equipment size, which makes the product suitable for a variety of services at the edge of the communication network and the end of the access layer or user side of the access and transmission. The product is suitable for the access and transmission of various services at the edge and end access layer of communication network or user side.

1. Adopting concise overall design scheme

In order to satisfythe need for compact size of SDH access equipmentapplied at the edge of the network, it is important to formulate a concise realization scheme to reduce the size and cost. In the design, we use a single-chip solution that can realize the required functions and provide perfect performance. The main chip completes all the main functions such as reconnection, mapping, line interface and common service interface, etc. As long as the connection of various service interface circuits, managementCPUand power supply and other related circuits can realize thevarious functions oflow-end multi-serviceSDHaccess equipment. Service interfaces and optical interfaces are connected to the main system in the form of modular slots to meet the needs of flexible multi-service configuration. This makes thePCBdesign more simple, the circuit board area is greatly reduced, power consumption has been reduced, but also due to the reduction of related peripheral circuits to enhance the stability of the system, simplify the production process, so that the commissioning and maintenance of the equipment is more convenient.

Simplified single-chip program schematic 1

2 . Highly integrated with diversified services, adopting high-density interconnection structure and component overlapping technology

The network application ofSDHaccess equipment is marginalized, requiring the equipment to have access to a variety of services. With the development and rapid popularization of the Internet, MAN and access network services show a trend of diversification and broadband, video on demand, data center interconnection,VPN, and e-commerce and other services come one after another,IPand other data services gradually become the fastest-growing demand. Therefore,the development trend ofSDHaccess equipment must be able to simultaneously support the transmission ofTDM-basedvoice services andaccess toIPand Ethernet services, and the continuous integration ofSDH/" target="_blank">ATMand switching functions, constitutingan SDH-basedmulti-service access platform. The increase of multi-service access types and theminiaturization ofSDHequipment design is a pair of contradictions, miniaturization design, we adopted a simple automatic identification method of service interface, and take full advantage of the pin multiplexing, so that a high degree of integration of diversified services to adapt tothe needs ofas many aseightdifferent service access. The service interface circuit adopts the zero-component overlapping technology, and the high-density interconnection structure inside the device makes the overall structure simple, smart and practical.

3. Simplify the interface circuit of upper and lower services

SDHaccess equipment can provide users with a larger capacity, the number of up and down the service interface is usuallymorethanPDHequipment. Due to the use of the main chip integrated into the main business interface functions, and built-in2Mclock smoothing and re-timing functions, and thus the design of the interface circuit of the upper and lower services can be greatly simplified. For example,2Mcircuitin the telecommunications networkis currently providing a major form of service, the traditionalSDHequipment usually need to useLIUcircuit, but now only need to design a simple electrical interface can be, so that the business interface board is simple and compact.

4. High-density installation of printed circuit boards

Designed to use small SMD components, not only can make the SDH access product miniaturization, but also to achieve a high degree of automation in the assembly of the entire equipment is very helpful.

5. Reduce design power consumption, improve heat dissipation

As far as possible, the use of low-power chips is animportant part of therealization ofthe miniaturization of SDH access equipment. The miniaturization of the equipment means that the integration degree is increased, the volume is reduced, the internal space is limited and air circulation is poor, if the components, especially the power consumption of the main chip is too high, then to solve the problem of heat dissipation and to maintain the silence will be more difficult, and the selection of lower-power consumption of the main chip and the business interface processor devices can better avoid these problems. In the design, we use theSDHmain chipwith1.2Vpower supply in thecore, and the service interface circuits, such as broadbandIPinterface, are also realized by choosing the industry's low-power Fast Ethernet chip, so that the total power consumption of the equipmentis comparableto that of the ordinaryPDHequipment, which greatly simplifies the structural and heat dissipation design, and reduces the complexity of the assembly and maintenance of the equipment.

IV. Conclusion

Through reasonable miniaturization design, we will have multi-service transmission function of the access layer SDH equipmentTOPAccessdesigned to be able to flexible networking; access services can be configured according to the needs of low power consumption, can be adapted to a variety of power supply conditions; small size, shape and structure of the equipment can be adapted to the environment in the user's end of the installation conditions, such as racks, wall-mounted mounting and other ways. With theSDHoptical transmission and access equipment gradually to the edge of the network and the convergence of multi-service access transformation, low-endSDHmulti-service access products market demand is a growing trend, the miniaturization of equipment to bring about production efficiency, cost reduction, power consumption reduction, stable processing quality and other advantages, to become thebest alternative tohigh-endPDHaccess equipment, and the rapid development of market applications to lay the foundation.The miniaturized design ofthis kind of low-costSDHmulti-service access equipmentprovides an opportunityfor operators to useSDHtechnology ona large scale in the metropolitan access network, which has good economic and social benefits.