Passive Optical Network (PON) is a network architecture that uses unpowered optical splitters to deliver data to multiple endpoints, such as homes, businesses, or, in this case, 5G stations. As 5G requires a significant increase in bandwidth and the ability to handle high data rates, PON offers a robust solution for meeting these demands.
Where is PON Used in 5G Deployments?
PON technology is primarily used in the fronthaul segment of 5G networks. The fronthaul connects the centralized baseband unit (BBU) to the distributed radio heads (RRH) or remote radio units (RRU). In this case, PON serves as a cost-effective and efficient solution for transmitting data over long distances. As demand increases, PON networks can easily scale by adding more optical fibers and splitters, making it ideal for 5G deployments, where numerous antennas are often deployed close to each other.
Can PON Handle the Necessary Bandwidth?
Yes, it can deliver the necessary bandwidth for 5G fronthauls. With the introduction of 10G PON (XGS-PON) and 25G PON (NG-PON2), the bandwidth capacity of PON networks has significantly increased. For example, 10G PON can deliver 10Gbps for both downstream and upstream traffic, while 25G PON can provide up to 25Gbps speeds. Moreover, PON can deliver symmetrical bandwidth, which means download and upload speeds are equal, ideal for real-time data processing.
In 5G deployments, multiple remote radio units (RRU) can be served by a single PON connection without latency. By configuring the Dynamic Bandwidth Allocation (DBA), the optical line terminal (OLT) can automatically adjust bandwidth allocation to each RRU during peak traffic periods, ensuring efficient data flow.
What You Need for PON Installation in 5G Stations?
PON allows for high-speed broadband connectivity, minimal latency and unlimited scalability in 5G deployments. The key components of a PON structure includes:
- Optical Line Terminal (OLT): Located at the service provider’s central office, it manages data traffic to and from the network. An OLT can handle up to 128 ONUs simultaneously, which makes it an ideal choice for point-to-multipoint (PTMP) networks.
- PLC Splitter: This passive optical splitter is used to distribute the optical signal from the OLT to multiple ONUs. Unlike active components, it doesn’t need power to operate and requires little maintenance.
- Optical Network Unit (ONU): Installed at the customer’s premises, it converts optical signals back to electrical signals for use by the 5G radio.
- Pre-terminated Fiber Optic Cables (SC connectors): These cables transmit data between the OLT, splitters and ONUs at high speeds. They are available in different configurations (2, 4 or 12 strands, direct-burial, etc.)
- Optical Transceivers (SFP+/XFP): Optical transceivers are required at BBU to send and receive optical signals.
How to Use PON in 5G Deployments?
PON provides a cost-effective, high-capacity solution to handle the large amounts of data transmitted between the BBUs and RRUs. Here’s a step-by-step guide on how to install PON in the fronthaul of 5G stations:
Step 1: Network Planning
Before installation, proper planning is crucial. You should identify where the OLT will be placed (usually in a centralized location such as a data center) and where ONUs will be installed (close to RRUs). Ensure the fiber length between the OLT and each ONU stays within the recommended range for optimal signal strength, typically up to 20km.
Step 2: Connect the OLT to the BBU
The BBU typically has high-speed optical ports (e.g., CPRI, eCPRI) for connecting to the fronthaul network. First, insert a compatible optical transceiver (SFP+/XFP) into the BBU base. Mount the OLT in a server rack and ensure it’s connected to a stable power source. Then, connect one end of the fiber cable into the SFP+ transceiver in the BBU and the other end into the corresponding port on the OLT.
- BBU Configuration: Configure the BBU to recognize the optical connection to the OLT. Set up the appropriate fronthaul protocols (eCPRI or CPRI) to ensure proper communication between the BBU and RRUs via the OLT.
Step 3: Lay Fiber Optic Cables
Lay the fiber optic cables along the planned routes, using protective conduits where necessary to avoid physical damage. Alternatively, you can opt for direct-burial fiber optic cables. Designed with high-strength armor, these cables can be buried directly underground without the need for additional conduits. However, due to the metallic components inside, it’s important to ground the cable in outdoor deployments.
Step 4: Install PLC Splitters
Install the passive optical splitters at strategic points in the network where the optical signal needs to be distributed to multiple ONUs. This allows one OLT to serve multiple RRUs. You can place splitters in junction boxes or cabinets close to where the fiber branches to the ONUs, and then connect the incoming fiber from the OLT to the splitter’s input.
Step 5: Connect the ONUs to the RRUs
The ONUs serve as the interface between the PON and the 5G radio units. You should install each ONU near the RRU using a waterproof enclosure if necessary. Connect the output fibers of the splitter to each ONU’s fiber line and use Ethernet cables to connect the ONU to the corresponding RRU.
Step 6: Configure the Network
After the configuration is done, the next step is to configure the PON network. First and foremost, you need to conduct end-to-end tests to confirm that data is being transmitted correctly from the OLT to the ONUs and from the ONUs to the RRHs/RRU. Use an optical power meter to verify the strength of the optical signals from the ONUs to the RRUs, ensuring the signal strength is strong enough. To optimize your PON network, you can set the appropriate settings on each ONU, such as VLANs, Dynamic Bandwidth Allocation (DBA), and QoS policies.
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