PON Module Parameters Guide: How to Choose the Best GPON & EPON Modules

Passive Optical Network modules play a crucial role in modern communication networks, providing efficient and stable solutions for data transmission. Depending on the connected devices, PON modules can be classified into Optical Line Terminal modules and Optical Network Unit modules.

Due to their distinct functions, OLT and ONU modules differ in transmission power, reception sensitivity, and overload optical power:

• Transmission Power: The intensity of the optical signal sent.

• Reception Power: The minimum detectable optical signal at the receiving end.

• Reception Sensitivity: Higher sensitivity means better performance at lower optical power, improving link budget and transmission efficiency.

• Overload Optical Power: The maximum optical power a device can handle without damage.

Currently, the two main standards organizations for PON networks, ITU and IEEE, have established different technical protocols to define the parameters of PON modules. Next, we will introduce the parameters of PON optical modules corresponding to these different protocols.

EPON and 10G-EPON Module

EPON Module

EPON module, defined by the IEEE 802.3ah standard in 2004, which can support the transmission rate of 1.25G upstream and downstream, and is widely used in the optical access network based on Ethernet.

EPON modules are divided into classes PX10 and PX20, with specific parameters as follows:

Device	OLT		ONU
PON Module	Class PX10	Class PX20	Class PX10	Class PX20
Transmitted Optical Power	-1~+4dBm	2~7dBm	-1~+4dBm	2~ 7dBm
Overload Optical Power	-3dBm	-6dBm	-3dBm	-6dBm
Sensitivity of reception	-23dBm	-27dBm	-23dBm	-27dBm

10G EPON Module

With the development of technology, 10GEPON (10 Gigabit Ethernet PON) emerged as the successor to EPON. According to the IEEE 802.3av standard, 10GEPON features symmetrical 10G uplink and downlink rates, but also offers a 1.25G uplink rate in some applications.

The standard also specifies PR10, PR20, and PR30 grades for 10GEPON modules, which have improved sensitivity and saturation ranges to better meet the needs of high-bandwidth network environments.

Device	OLT			ONU
PON Module	Class PR10	Class PR20	Class PR30	Class PR10	Class PR20	Class PR30
Transmitted Optical Power	-1~+4dBm	2~7dBm	4~9dBm	-1~+4dBm	2~7dBm	4~9dBm
Overload Optical Power	-8dBm	-9dBm	-10dBm	-8dBm	-9dBm	-10dBm
Sensitivity of reception	-28dBm	-29dBm	-30dBm	-28dBm	-29dBm	-30dBm

GPON, XGPON and XGSPON Module

GPON Module

Another key PON technology is GPON (Gigabit Passive Optical Network), which supports upstream rates of 1.25G and downstream rates of 2.5G, demonstrating excellent performance in terms of transmission rates and coverage.

ITU-T G.984 standard for GPON modules defines class B+ and class C+. The specific performance parameters:

Device	OLT		ONU
PON Module	Class B+	Class C+	Class B+	Class C+
Transmitted Optical Power	1.5~5dBm	3~7dBm	0.5~5dBm	1.5~5dBm
Overload Optical Power	-8dBm	-12dBm	-8dBm	-12dBm
Sensitivity of reception	-27dBm	-32dBm	-27dBm	-32dBm

10G GPON--XG-PON & XGS-PON Module

As the demand for bandwidth continues to grow, GPON has gradually evolved into XG-PON modules transmission supported by the ITU-T G.987 protocol, which features asymmetric 2.5G upstream/10G downstream rates. To meet the needs of certain ultra-high-speed transmission scenarios, XGSPON (10 Gigabit-capable Symmetrical Passive Optical Network) technology, with symmetrical data rate, has also emerged, further enhancing the support for symmetrical bandwidth. The ITU classifies 10G rate PON modules as class N1/N2.

It is worth noting that apart from the differences in upstream and downstream transmission rates, the XGPON and XGSPON modules are largely consistent in other parameters, allowing you to make flexible choices based on your transmission rate requirements:

Protocol Standards	XGPON	XGSPON
Downstream Rate	10 Gbps	10 Gbps
Upstream Rate	2.5 Gbps	10 Gbps

 

Device	XG(S)-PON OLT		XG(S)-PON ONU
PON Module	Class N1	Class N2	Class N1	Class N2
Transmitted Optical Power	1.5~5dBm	3~7dBm	0.5~5dBm	1.5~5dBm
Overload Optical Power	-8dBm	-12dBm	-8dBm	-12dBm
Sensitivity of reception	-27dBm	-32dBm	-27dBm	-32dBm

XG(S)-PON & GPON Combo Module

In practical scenarios, network upgrades often require compatibility with existing equipment. To ensure a smooth transition from GPON to 10G-PON, OLTs need to support multiple protocols. This necessity has led to the development of XG(S) PON & GPON Combo OLT module. Combo PON modules can simultaneously support two network protocols, allowing operators to upgrade their networks without replacing terminal devices, thus enhancing upgrade flexibility and cost-effectiveness.

The XG-PON Combo OLT includes two specifications, B+ and C+, with optical link budgets of 28dB and 32dB, respectively. This supports various customer requirements for different optical power budget scenarios.

In addition to the integration of GPON and XGPON, GPON also integrates with XGSPON to form the XGSPON/GPON Combo OLT module. This module includes two specifications, N1 and N2, with optical link budgets of 27dB and 31dB, supporting higher-speed network transmission.

XG-PON & GPON Combo OLT Module

PON Module	Class B+	Class C+
Transmitted Optical Power	1.5~5dBm	3~7dBm
Overload Optical Power	-8dBm	-12dBm
Sensitivity of reception	-27dBm	-32dBm

XGS-PON & GPON Combo OLT Module

PON Module	Class N1	Class N2
Transmitted Optical Power	4~9dBm	7~11dBm
Overload Optical Power	-8dBm	-12dBm
Sensitivity of reception	-27dBm	-30dBm

How to Connect The OLT and ONU Modules to Modern Networks

In PON network deployment, to ensure low-loss and high-efficiency transmission between OLT and ONU modules, it is recommended that matching module types be selected for connection. For example, when using a B+ module in the OLT, it is advisable to pair it with a B+-type ONU module.

Key points to ensure compatibility include:

• 1. Standardized Protocols: Ensure the selected PON modules comply with the same protocol standards. For instance, due to protocol differences, EPON and GPON modules are generally not interchangeable.

• 2. Optical Power Requirements: The transmitted optical power of the OLT should be higher than the receiving sensitivity of the ONU to ensure effective signal transmission. If the transmitted power is insufficient, the ONU may not receive enough signal.

• 3. Saturation Power: Pay attention to the saturation power of the ONU, which is the maximum optical signal power that the ONU can receive. If the OLT's transmitted power exceeds the saturation threshold of the ONU, it could cause signal distortion. When selecting PON modules, ensure the transmitted power of the OLT is within the receiving sensitivity range of the ONU and below its saturation power.

• 4. Wavelength Compatibility: Different PON modules (such as GPON and XG-PON) use different wavelengths for signal transmission. Even if the optical power matches, incompatibility in wavelength can cause the devices to malfunction.

When choosing modules to insert into devices, it's essential to note that module compatibility varies among manufacturers, so it's crucial to follow the manufacturer-provided guidelines for connections.

For example, most of FS's PON modules are universal PON modules, with some modules compatible with devices from companies like Nokia, Huawei, Ericsson, CommScope, Fiberhome, and others.

When selecting modules, you need to pay attention to whether the modules are compatible with the devices, whether parameters like transmission power and sensitivity between modules match, and ensure proper connection according to the device's manual to achieve optimal performance and compatibility.

Summary

The critical role of PON optical modules in these applications highlights their importance in modern communication networks. As technology continues to advance and user demands increase, PON technology will find even broader applications. FS, as a leader in the optical networking field, offers comprehensive network solutions that help businesses and households achieve efficient and stable connectivity. This ensures they are well-equipped to meet the challenges of higher bandwidth and more complex network demands in the future.