ZTE´s Optical Transmission Products Used in National Backbone Network of Indonesia

The platform has the following features:
    (1) Supporting long-span networking and multi-span mixed networking 
    (2) Open multi-service access mode and Optical Transfer Unit (OTU) supporting multi-service access
    (3) Strong service convergence ability, including the convergence of 4 STM-1/4 services, 2 GbE services and 4 STM-16 services
    (4) Flexible filter design with a serial/parallel structure, supporting add/drop of 1-40 waves
    (5) Flexible networking modes, including link networking, ring networking and tangent ring networking
    (6) Perfect power management technologies
    (7) Optical performance monitoring
    (8) Accurate fault location and precise performance monitoring
    (9) Outband Forward Error Correction (FEC) function
    (10) Dispersion management technology
    (11) Powerful and unique NMS
    (12) Flexible structure and smooth upgrading ability

1 Technical Features of ZTE’s  DWDM System
The toll backbone wave division equipment of ZXWM M900 backbone transmission platform is well designed for
large-capacity optical transmission. It can fully satisfy the networking and management requirements of diversified users and be fit for various toll backbone networks. The system supports up to 40 working wavelengths and up to 400 Gb/s transmission capacity, and the wavelength selection and interval are in strict compliance with ITU-T Recommendations. It supports multiple networking modes, such as the link, ring and ring tangent modes. ZXWM M900 has two types: the integrated model and the open model. The integrated system can directly connet ZXSM-2500 SDH or ZXSM-10G, which meets the requirements for optical interfaces specified in the G.692 Recommendation. The open system adopts the wavelength conversion technology. It can be configured with the wavelength transfer unit that enables multi-service access. In addition to expanding the trunk distance and capacity of SDH equipment from different vendors and satisfies the ITU-T specifications for optical interfaces, it can also access service signals, such as IP data signals. The system has the following features:

    (1) Supporting long-span networking and multi-span mixed networking
    In consideration of the features of the toll backbone network, the system supports both long-span networking as well as mixed networking of various spans to meet the networking requirements of different backbone networks.

    (2) Open multi-service access mode and Optical Transfer Unit (OTU) supporting multi-service access
    ZXWM M900 adopts an open design mode. It makes use of the O/E/O wavelength conversion technology to convert accessed optical signals into optical signals that satisfy the specifications of G.692 and G.691 Recommendations. It can not only transparently access the STM-N signals from any SDH equipment, but also bear optical signals of other formats, like POS, GE and ATM. Users’ investments can accordingly be protected.

    (3) Strong service convergence ability, including the convergence of 4 STM-1/4 services, 2 GbE services and 4 STM-16 services
    Wavelength resources can be effectively used via service convergence. The system also enables performance monitoring and overhead transparent transmission of services.

    (4) Flexible filter design with a serial/parallel structure, supporting add/drop of 1-40 waves
    Metropolitan Area Network (MAN) equipment is required to have flexible scalability due to the uneven distribution of MAN services and uncertainty of future service expansion. The filter of ZXWM M900 adopts a modular design and enables the scalability from 1 to 40 waves. Requirements for MAN node upgrading can accordingly be satisfied.
 

    (5) Flexible networking modes, including link networking, ring networking and tangent ring networking 
    The Optical Supervision Channel (OSC) board, Network Element Control Processor (NCP) board and OHP board of ZXWM M900 support cross-networking. Hence the system can have complicated network topologies, like link, star, cross, tangent ring and intersection networking. It is applicable for various layout modes of backbone networks.

    (6) Perfect power management technologies
    To ensure network performance, the ZXWM M900 system adopts a perfect power management technology to adjust and control the power of system nodes.

    System power management technologies include the power pre-balance technology and the intelligent optical amplifier control technology. The power pre-balance technology is used to adjust the output power of the optical transfer unit via the Network Management System (NMS) to ensure the balance of optical power in each channel of the optical receiving end. The intelligent optical amplifier, in addition to providing gain-flat and gain-locking functions, also offers gain adjusting and output power transient compressing functions.

    (7) Optical performance monitoring
    There are three optical performance monitor units in the system, which are used to measure such parameters of each optical channel as optical power, central wavelength and optical Signal Noise Ratio (SNR). It also sends the data to the NMS for users’ check.

    (8) Accurate fault location and precise performance monitoring
    The optical forwarding board of the ZXWM M900 system provides the B1 and J0 byte parity check function. Its service convergence board enables performance check on the tributary end and the group end. It can correctly fix fault locations and types.

    In the ZXWM M900 system, boards of the main optical channel adopt wide-range and high-precision power collection and monitoring technologies, and the measurement error is less than 1dB. It can reflect the system performance accurately.

    (9) Outband Forward Error Correction (FEC) function
    The outband FEC technology can be used to improve system transmission performance. It can improve the optical SNR by about 6 dB and enables extra-long-span transmission. This can meet the requirements of the MAN on the 10G services. In different configurations, boards with the outband FEC function can enable outband FEC coding, outband FEC decoding, outband FEC coding after decoding, and non outband FEC coding.

    (10)  Dispersion management technology
    In 10 Gb/s transmission or 2.5 Gb/s and 10 Gb/s mixed transmission, dispersion limitation must be taken into considerations to enable long-distance transmission in the protection state. In system design, the dispersion management technology is adopted to enable broadband dispersion compensation. This technology enables high-speed long-distance transmission and satisfies the requirements for transmitting 10Gb/s signals.

    (11)  Powerful and unique NMS
    ZXWM-NMS provides friendly and easy-to-operate user interfaces. It supports multi-layer management on the Network Element (NE) layer, NE management layer and Network Management (NM) layer. In addition to the standard alarm management, performance management, configuration management, maintenance management and system management functions specified in the ITU-T Recommendations, it also provides the following features:

• It adopts the object-oriented technology to realize the three-layer C/S structure that separates the interface, service and data. The system provides fine scalability and adaptation.
• It adopts the standard ECC dynamic routing protocol to facilitate the construction of complicated networks.
• It adopts the main/standby station management technology to enable the real-time synchronization and automatic switching of data between the active and the standby stations.
• It enables remote software downloading. Via the latest technologies, it enables online upgrading of all software (including foreground/background NM software and
  single-board embedded software) without interrupting services.
• It provides a remote control optical interface to adjust optical interface parameters remotely, like wavelength, power and gain.

    (12)  Flexible structure and smooth upgrading ability 
    The system adopts a modular structure. The backplane interfaces of all optical channel boards are the same, which enables board intermixing. The system can hence be flexibly configured. System upgrading and expansion can be implemented by adding optical forwarding subracks and boards in the same rack. So the system has fine compatibility and scalability.

    The system adopts multi-rack management technologies. Each NCP board in the ZXWM M900 system provides the multi-rack management function. More spaces for smooth system upgrading are provided.

2 Project Overview
On August 12, 2004, ZTE won the tender of supplying optical network products to the national backbone network transmission project of TELKOM, the biggest fixed network operator in Indonesia. The ZXWM-M900 backbone network OTM equipment, ZXSM-10G backbone network SDH transmission equipment and ZXSM-2500C will be provided to construct the national backbone transmission network of TELKOM. At present, TELKOM requires only the bearing of two traditional SDH services, E1 and STM-1. The network solution of ZTE, however, can also satisfy the future requirements for new data services in addition to satisfying current service requirements and reserving big expansion spaces.

    As shown in Figure 1, the networking topology of the project is a dual-node tangent ring. Each node on the ring adopts ZXWM M900, which is configured in the back-to-back OTM mode; this can fully ensure the add/drop of 32 waves (to be upgraded to 40 waves); on the public crossing nodes of the two rings, the wave channel protection function is provided to further increase network security.

    To cooperate with the DWDM-layer solution, ZTE adopts the ZXSM-10G and the ZXSM-2500C to add/drop and schedule large-capacity services.

    ZTE’s optical transmission network solution provides complete protection functions on services in addition to ensuring service capacity. The network layer enables the MS-SPRing (Multiplex Section Shared Protection Ring); the NE layer provides 1+1 or 1:1 protection for public boards; the NE layer provides 1:N protection for electric service boards.

2.1 System Structure
According to the initial traffic demands, two 10 G services will be provided in this phase of the project. With the development of network services,  wavelength can be upgraded online without affecting existing services so as to fully satisfy the demands for future service developments.

2.2 Services Supported
The system supports multiple services: SDH services, including STM-1/-4/-16/-64; SONET services, including OC-3/-12/-48/-192; ATM services or POS, including STM-1c/4c/16c; Ethernet services, including 100 M/GE services, Enterprise Systems Connection (ESCON), and Fiber Channel (FC) services. For other services, it provides flexible multi-rate interfaces to bear any services at the rate of 45 Mb/s-2.5 Gb/s.

    To solve the problem of low bandwidth usage rate caused by small-granule services, the ZXWM M900 system adopts the T-MUX (Transparent-Multiplexing) mode to implement binding transmission of subrate bandwidth. This can greatly reduce investments and operation costs and overcome the complexity and diversity of MAN services.

2.3 Protection Mechanism
In this phase of the project, the SDH layer enables 10 G MSSPRing protection. As the project design has fully considered the OSNR of the biggest distance and dispersion, the system can be upgraded online for service development. Optical layer protection can be finally executed.

2.4 System Upgrading
    (1)Increase of wavelength number
    The wavelength number can be added and configured without limitation within 40 waves. In the future, with the development of network services, online upgrading of wavelength can be implemented without affecting existing services to cater to future requirements.

    (2)Configurable upgrading in fixed directions
    New services can be upgraded to enable the add/drop function, while existing services keep their original configuration without being interrupted. If existing services are upgraded to enable the add/drop function, the services would be interrupted temporarily.

Manuscript received: 2004-09-29