Case Details
1. What is XGS-PON?
Both XG-PON and XGS-PON belong to the GPON family. From a technical perspective, XGS-PON is a technological evolution of XG-PON.
Both XG-PON and XGS-PON are 10G PONs. The main difference is that XG-PON is an asymmetric PON with 2.5G/10G upstream and downstream rates, while XGS-PON is a symmetric PON with 10G/10G upstream and downstream rates.
The main PON technologies currently in use are GPON and XG-PON, both of which are asymmetric. Because user upstream and downstream data flows are generally asymmetric, for example, in a first-tier city, the upstream traffic of the OLT averages only 22% of the downstream traffic. Therefore, the technical characteristics of asymmetric PON generally match user needs. More importantly, the lower upstream rate of asymmetric PON reduces the cost of ONU transmission components such as lasers, resulting in a correspondingly lower device price.
2. Coexistence of XGS-PON with XG-PON and GPON
XGS-PON is a technological evolution of GPON and XG-PON, supporting mixed access of three types of ONUs: GPON, XG-PON, and XGS-PON.
2.1 Coexistence of XGS-PON and XG-PON
Like XG-PON, XGS-PON uses a broadcast method for downstream transmission and a time-delayed multiple access (TDMA) method for upstream transmission.
Since XGS-PON and XG-PON share the same downstream wavelength and rate, XGS-PON does not differentiate between XGS-PON and XG-PON ONUs in downstream transmission. The optical splitter broadcasts the downstream optical signal to each XG(S)-PON (XG-PON and XGS-PON) ONU in the same ODN link. Each ONU selects its own signal and discards all other signals.
XGS-PON transmits data in upstream transmission according to time slots, with ONUs transmitting data within the time slots permitted by the OLT. The OLT dynamically allocates timeslots based on the traffic demands of different ONUs and the ONU type (XG-PON or XGS-PON). The data transmission rate in timeslots allocated to XG-PON ONUs is 2.5 Gbps; the data transmission rate in timeslots allocated to XGS-PON ONUs is 10 Gbps.
As can be seen, XGS-PON naturally supports mixed access with both XG-PON and XGS-PON ONUs.
2.2 Coexistence of XGS-PON and GPON
Because the upstream and downstream wavelengths differ from GPON, XGS-PON uses a combo solution to share the ODN with GPON.
The XGS-PON combo optical module integrates a GPON optical module, an XGS-PON optical module, and a WDM combiner.
In the upstream direction, after the optical signal enters the XGS-PON combo port, the WDM filters the GPON and XGS-PON signals based on wavelength and then routes the signals into different channels.
In the downstream direction, signals from GPON and XGS-PON channels are multiplexed using WDM, and the mixed signal is transmitted downstream via the ODN to the ONUs. Due to different wavelengths, different ONU types use internal filters to select the wavelength they require to receive the signal.
Because XGS-PON naturally supports coexistence with XG-PON, the XGS-PON combo solution supports mixed access of GPON, XG-PON, and XGS-PON ONUs. XGS-PON combo optical modules are also called tri-mode combo optical modules (while XG-PON combo optical modules, because they support mixed access of GPON and XG-PON ONUs, are called dual-mode combo optical modules).
This concludes today's introduction. In addition, we have the related XGSPON COMBO business boards CSHF and GFCH for sale. If you need them, please feel free to contact us.
