XG-GPON and XGS-PON: Understanding the Principles and Applications

The Evolution of GPON Technology

GPON(Gigabit-capable Passive Optical Network) is the access technology of a passive optical network (PON) based on the ITU-T G.984.x standard. Its development has undergone continuous evolution and improvement, while also driving the development and popularization of fiber optic access networks. With the increasing demand from users for higher bandwidth, new generations of PON technology such as XG-PON(10 Gigabit-capable Passive Optical Network) and XGS-PON(10 Gigabit Symmetrical Passive Optical Network) have emerged.

XG-PON and XGS-PON are collectively referred to as 10G GPON. XG-PON is an upgraded version of GPON technology, capable of providing up to 10 Gbps downstream bandwidth and 2.5 Gbps upstream bandwidth. XGS-PON, on the other hand, is a further development of GPON technology aimed at providing symmetrical upstream and downstream bandwidth, with both upstream and downstream data transmission rates reaching 10 Gbps.

These technologies offer higher rates and bandwidth than traditional GPON, catering to the growing demand for broadband and emerging applications such as 4K/8K videos, virtual reality (VR), and augmented reality (AR).

For more details about the difference between GPON, XG-PON, and XGS-PON, please check: GPON vs. XG PON vs. XGS PON: Which PON Technology Is Right for Your Network?

Unlock Network Architecture: XG-PON and XGS-PON

In fact, XG-PON and XGS-PON have the same network structure as GPON, consisting of OLT, ONU, and ODN, following the standard P2MP architecture of PON networks, and can be widely used in FTTx scenarios.

• OLT: A convergence device placed at the central office that terminates the PON protocol.

• ONU: A user-side unit or terminal located on the client side, providing various interfaces to the user.

• ODN: Consisting of optical fibers and one or more Passive Optical Splitters (POS), it connects the OLT and the ONU.

For more information about these components, please check: Decoding OLT, ONU, ONT, and ODN in PON Network

Exploring the Working Principles of XG-PON and XGS-PON

10G GPON uses Wavelength Division Multiplexing (WDM) technology to achieve bidirectional data transmission on a single fiber within the same ODN network by using different wavelengths for upstream and downstream, as shown in the figure:

Downstream Data Transmission

The downstream link refers to the process of data transmission from the OLT to the ONU. In this direction, data is sent via broadcasting. The OLT broadcasts data to all ONUs, and each ONU selects and receives the data intended for itself, discarding other data.

The diagram below illustrates the downstream service forwarding process. On the OLT, data flows are encapsulated into GEM ports within the service processing unit. The OLT broadcasts the data encapsulated into GEM ports to all ONUs. Upon receiving the data sent by the OLT, each ONU determines whether to process or discard the data flow based on the XGEM port ID.

Upstream Data Transmission

The upstream link refers to the process of data transmission from the ONU back to the OLT. To avoid signal conflicts and interference, the upstream link is managed using a Time Division Multiple Access (TDMA) mechanism. The OLT allocates time slots for each ONU, and each ONU sends data within its designated time slot to prevent data collisions. The optical signals aggregated at the OLT are converted back into electrical signals for processing, and the data is forwarded to higher-level networks.

The upstream service forwarding process is illustrated in the diagram below. On the ONU, data flows are encapsulated into the corresponding GEM ports and then mapped to the corresponding T-CONTs. The OLT schedules data flows based on T-CONTs and sends them to the OLT in sequence according to time slots. The OLT then decapsulates the data flows from the GEM ports and forwards them to the corresponding service units.

How to Deploy 10G GPON Network

10G GPON Network

10G GPON network refers to a network infrastructure entirely based on 10 Gigabit Passive Optical Network (GPON) technology. The 10G GPON OLT connects to 10G GPON ONUs, with signal transmission exclusively over the ODN network. This network configuration features a uniform device type (solely 10G GPON equipment), making it easy to deploy and maintain. It is suitable for new deployments in 10G GPON FTTx network scenarios.

10G GPON and GPON Hybrid Networking

This networking method involves having both 10G GPON and GPON equipment within the same PON network, sharing a single ODN. In a hybrid network, 10G GPON and GPON access boards are inserted into the same OLT to handle access services. Due to the different wavelengths used by 10G GPON and GPON (10G GPON typically uses 1577nm for downstream and 1270nm for upstream, while GPON uses 1490nm for downstream and 1310nm for upstream), passive xWDM/xPON Multiplexers is needed for wavelength allocation. It is important to note that on the OLT, a 10G GPON access board can only connect to 10G GPON ONUs, and a GPON access board can only connect to GPON ONUs.

This networking approach achieves a smooth transition from GPON to 10G GPON while maximizing investment protection. However, the coexistence of 10G GPON and GPON devices in the network also presents challenges in terms of network complexity and maintenance.

10G GPON & GPON Shared Board Hybrid Networking

The key difference between this hybrid networking method and the previous one is that it uses shared service boards that support simultaneous processing of 10G GPON and GPON signals. These types of service boards can handle two different wavelengths simultaneously. This method uses built-in xWDM/xPON Multiplexers, commonly referred to as Combo-PON equipment.

This type of networking provides a high degree of flexibility, allowing 10G GPON and GPON services to be deployed flexibly on the same OLT according to demand. By using shared service boards, the cost of equipment procurement can also be reduced, resulting in cost efficiency.

Summary

As the next-generation PON technology, 10G GPON meets the increasing demands of high-bandwidth network applications while enabling high-bandwidth access at a lower cost. FS supports the customization of XG(S)-PON devices and the FS solutions team will continue to provide you with reliable and professional services. For more information on PON technology and equipment, please visit FS PON Networks.