Advantages, Application and Development of OXC

Compared with ROADM, OXC can greatly reduce the space, reduce power consumption and simplify internal fiber connections through highly integrated board functions and optical backplane. The 20-dimensional OXC only requires one cabinet, reducing the space by 2/3. Only more than 30 single boards are needed, the number of single boards used is reduced by 2/3, and the corresponding power consumption is also reduced. The optical fiber connections within the site are all through the optical backplane, and the fiber connection is completed after the plug-in board is completed, which improves the startup efficiency and reduces the maintenance cost.

High integration, small footprint, saving room space

ROADM sites need to use optical amplification, WSS, OSC, OTDR, OP and other separate boards. There are many types and large quantities of boards, and multiple cabinets are required. OXC has been optimized and highly integrated with related single board functions. The optical circuit board and optical add/drop board only occupy one slot to achieve line direction access and 32-wave service add/drop; only one cabinet is needed to achieve 32-dimensional optical crossover. Scheduling, saving 2/3 of the floor space.

Energy-saving, easy to activate, easy to maintain, and low costs in operation and maintenance

The 16-dimensional OXC only requires one main and one backup 63A power supply, and the 32-dimensional OXC only requires two main and two backup 63A power supplies. Compared with ROADM, the power consumption of the equipment is reduced and the number of power terminals required is reduced. At the same time, the use of optical backplane solves the problems of large number of internal fiber connections, low startup efficiency, and difficult maintenance of ROADM, and realizes "zero" internal optical fiber connection. The fiber is connected by plugging in the board; inserting an optical line single board, connecting the line fiber for software Configuration can activate 1D; an optical up and down board, connect the relevant service boards, and set up the software to activate the service, which is convenient; supports optical layer OAM, and can monitor the service rate, optical power, and central wavelength of each wavelength channel , source node and other information and perform route verification to facilitate fault and reduce operation and maintenance costs.

Support ultra-large capacity optical cross-connection and low latency

It supports CE, C++ and L++ bands. A single cabinet supports 32 dimensions and can support 1024T optical cross-connection to meet the demand for trunk line and metro optical cross-connection capacity. It can be used with branch line-integrated service boards to achieve wavelength-level cross-connection scheduling; and Used together with OTN equipment, sub-wavelength and wavelength-level cross-scheduling can be achieved. Optical cross-connect nodes are connected only through optical fibers, achieving almost no latency.

Network intelligence

An intelligent network should support functions such as automatic discovery of network topology and resources, service provisioning and control, route calculation, intelligent scheduling, and network performance monitoring. As a physical layer device, OXC supports the CDC function, which can solve the problem of wavelength conflicts, increase the flexibility of optical cross-scheduling, and improve the utilization of network resources; it supports FlexGrid, which can realize dynamic adjustment of transmission pipeline bandwidth and realize wavelengths such as 100G and beyond Intelligent scheduling; supports optical domain balancing and automatic optical power optimization, reduces WSS collusion costs, improves system transmission performance, increases available routes, and improves network survivability. The application of OXC in trunk and metropolitan area networks, especially in high-dimensional networks, provides guarantee for network intelligence.

Starting in 2018, various domestic manufacturers have successively launched 16/20/32-dimensional OXC products, replacing ROADM for commercial use in the trunk and metro networks of operators such as China Mobile, China Telecom and China Unicom.

The transmission distance of the trunk network is thousands of kilometers, and it generally uses a star network. There are not many physical links, and the line dimension is not high. However, the node business volume is large (especially the core node), and the business takes up a lot of OXC dimensions. The 16/20 and 32-dimensional OXC have 16, 20 and 32 slots respectively. Each slot can be inserted into an optical line board or an optical add and drop board to achieve one optical line directional access or a set of 32-wave service add and drop. When designing the network, you need to consider the current line dimensions and business levels. At the same time, it is necessary to consider the future line dimension and upstream and downstream business expansion needs, and reserve slots for later expansion. Later expansion is very convenient. Inserting an optical circuit board can add a line dimension, and inserting an optical add/drop circuit board can add a set of 32-wave local add/drop. The local add/drop circuit board has two expansion ports. Each expansion port can implement 32 waves of services. When the OXC slot is tight, it can cooperate with the WSS board on the transmission subrack to achieve 96 waves of services in a single OXC slot.

The transmission distance of metropolitan area networks is short, generally hundreds of kilometers, and Mesh networking is used. It has many physical links and many line dimensions, and each dimension has business up and down. The core node lines have many dimensions and the upstream and downstream traffic volume is large; the non-core node lines have few dimensions and have little expansion potential. Similarly, the dimensions of OXC need to be determined based on the current and subsequent line dimensions and upstream and downstream business needs. Generally, the core nodes of domestic metropolitan area networks use 32-dimensional OXC, and the non-core nodes use 16-dimensional OXC.

Network development has brought about an increase in the optical layer scheduling dimension of core nodes, and at the same time, the upstream and downstream traffic of core sites has increased. In the northwest ring network of China Telecom, the Taiyuan hub site has reached 57 dimensions. Currently, the commercially available 1×N WSS only supports up to 32 dimensions, which cannot meet the high-dimensional requirements of the core nodes of the existing network. With the further development of the network, there are increasing demands for high dimensions, and high-dimensional 64 or 128 dimensions will become a development direction of OXC.

In high-dimensional situations, it is easy for local add and drop traffic to conflict with services of the same wavelength from different line dimensions, so CDC requirements (wavelength-independent, direction-independent, and competition-independent) have become important requirements for OXC. Currently, commercial M×N WSS has 8/16 dimensions, and the number of add and drop ports is generally 24, which cannot meet the needs of high dimensions and large number of add and drop local services. At the same time, M×N WSS does not yet support the L++ band. High-dimensional, multi-port CDC and band expansion are also a development direction of OXC.

As networks become more meshed and intelligent, the requirements for optical cross-connect scheduling capabilities are getting higher and higher. ROADM uses separate single boards, which has problems such as large floor space, high power consumption, large number of internal fibers, and error-prone startup and maintenance. Only 9-dimensional and 20-dimensional devices are commercially available. OXC solves the above problems through optical backplanes, highly integrated optical circuit boards and optical add-and-drop circuit boards. OXC supports ultra-large cross-connect capacity, has the advantages of high integration, small footprint, convenient startup and operation, and is green and energy-saving. It has been widely used in the trunk lines and metropolitan area networks of operators such as China Mobile, China Telecom, and China Unicom. At the same time, with the development of the network, supporting higher dimensions, multi-port CDCF, and supporting L++ band CDCF are also issues that need to be further solved.