High-Performance Compact CWDM Mux Demux Application Case: Urban Rail Transit Backbone Network Upgrade

Guangzhou Metro Line 12, as a key urban rail transit line connecting the central urban area and the new city, has a large passenger flow and high requirements for operational safety and efficiency. The original communication network adopted traditional point-to-point transmission, which could not meet the growing demand for:

• Real-time transmission of train control signals, video surveillance, and passenger information systems
• Stable operation of new services such as intelligent operation and maintenance and edge computing
• Limited fiber resources in the existing tunnel pipeline, making it difficult to lay new fibers

Core customer requirements:

• Significantly save fiber resources while improving network bandwidth capacity
• Ensure stable transmission of multiple services with low latency and low loss
• Adopt a compact, high-performance solution suitable for limited space in subway equipment rooms
• Support flexible expansion of services and wavelengths in the future

HJY’s technical team designed a customized CWDM solution based on the customer’s needs, deploying high-performance compact CWDM Mux Demux equipment in the core equipment room of the subway line and the equipment rooms of each station.

Key Solution Features:

• Free Space Technology: Adopting high-quality Free Space design, the equipment achieves ultra-low insertion loss, ensuring stable signal transmission over long distances in tunnels.
• Customized Fiber Mode: A hybrid deployment of single-fiber and dual-fiber modes was adopted:
  • Single-fiber bidirectional Mux Demux: Used in sections with limited fiber resources, realizing bidirectional transmission over a single fiber and saving 50% of fiber resources.
  • Dual-fiber bidirectional transmission: Used in core nodes to provide higher bandwidth and more stable signal quality.
• Customized Channels & Wavelengths: Customized 8-channel CWDM wavelengths (1270nm, 1290nm, 1310nm, 1330nm, 1550nm, 1570nm, 1590nm, 1610nm) with 20nm spacing, matching the customer’s existing equipment and service planning.
• Compact Package: The compact design of the equipment perfectly fits the limited space of subway equipment rooms, reducing the footprint of communication equipment by 40%.

Service Bearer:

• Fiber Resource Saving: Single-fiber bidirectional technology saved 50% of fiber resources in tunnel sections, avoiding the high cost of laying new fibers.
• Bandwidth & Stability: The network bandwidth was increased by 8 times, and the Free Space design ensured ultra-low insertion loss, with zero packet loss and stable latency during 7*24 operation.
• Space Optimization: The compact package reduced the equipment footprint by 40%, effectively utilizing the limited space of subway equipment rooms.
• Flexible Expansion: Customized wavelengths and channels support the flexible addition of new services in the future, protecting the customer’s investment.

"HJY’s customized CWDM Mux Demux solution perfectly solved our pain points of limited fiber resources and insufficient bandwidth. The high-performance, compact equipment is very suitable for the subway environment, and the technical support throughout the process is professional and efficient. It has become a key part of our intelligent rail transit construction."

—— Director of Information Department, Guangzhou Metro Group

• Customized Solutions: Provide flexible CWDM solutions with customized fiber modes, channels, and wavelengths to meet the specific needs of different industries.
• High Performance & Reliability: Free Space technology ensures ultra-low insertion loss and stable transmission, suitable for harsh environments such as urban rail transit.
• Space-Saving Design: Compact package reduces equipment footprint, ideal for scenarios with limited space.
• Full Lifecycle Support: From solution design, equipment customization to on-site deployment and after-sales maintenance, provide one-stop service for customers.