10GEPON key technologies: Asymmetric–rate and Symmetric–rate PHY for PON

“PRX power budget describes asymmetric–rate PHY for PON operating at 10 Gbit/s downstream and 1 Gbit/s upstream.

PR power budget describes symmetric–rate PHY for PON operating at 10 Gbit/s downstream and 10 Gbit/s upstream.”

Physical Medium Dependent Sublayer

  10GEPON defines and expands the parameters related to physical medium dependent sublayer, including optical power budget and optical transceiver characteristics.

Optical power budget

  10GEPON currently specifies three types of optical power budgets, PR10/PRX10, PR20/PRX20 and PR30/PRX30, as shown in the figure. The PRX and PR types are defined as follows:

  • The PRX-type power budget refers to an asymmetric rate PON physical layer of 10 Gbps downlink and 1 Gbps uplink on a single mode fiber.
  • The PR-type power budget refers to the symmetric PON physical layer of 10 Gbps downstream and 10 Gbps upstream over a single mode fiber.
DescriptionLow power budget Medium power budget High power budget Unit
Fiber count1null
Upstream rate1.2510.31251.2510.31251.2510.3125GBd
Downstream wavelength1577nm
Downstream wavelength tolerance-2,+3nm
Upstream wavelength131012701310127013101270nm
Upstream wavelength tolerance±50±10±50±10±50±10nm
Maximum transmission distance≥10≥20≥20km
Maximum path loss202429dB
Minimum path loss51015dB
As long as the optical power budget and other optical layer specifications are met, the system may exceed the maximum transmission distance for a specific optical power budget level.

  The 10GEPON power budget can support 20km transmission distance and 1:32 split ratio. Symmetrical PMD sub-layer PR10, PR20 and PR30 channel loss and cost please refer to table following.

DescriptionPR10 PR20 PR30 Unit
Fiber type②Single mode fiber
Nominal distance④102020km
Available power budget⑤2321.52725.53230.5dB
Channel loss (maximum)⑥202429dB
Channel loss (minimum)⑦51015dB
Optical path cost⑧32.531.531.5dB
Optical return loss of ODN20dB
①US stands for uplink and DS stands for downlink
②Single mode fiber should meet the requirements of IEC60793-2 B1.1, B1.3 and ITU-T G.652, G.675. If ODN can meet the requirements of loss and dispersion, other types of optical fibers can also be used.
③Nominal transmission wavelength is 1577nm
④The nominal distance represents the desired maximum distance that the PMD can achieve in a typical ODN. Different odns may result in greater or smaller distances in the user's actual network.
⑤The available power budget assumes a bit error rate of 10^(-3) for the PMD service interface. Through the fec function of the pcs layer, the 10^(-12) bit error rate required by the PCS service interface can be achieved.
⑥The path loss is based on the cable attenuation of the target transmission distance and the nominal measurement wavelength. Good channel loss includes loss of active connectors, fiber splices, and other passive components such as optical splitters.
⑦These values ​​refer to the minimum loss between transmitter and receiver at the PR10, PR20, and PR30 power budget levels, and are the minimum attenuation required for PMD testing.
⑧The optical path cost refers to the difference between the available power budget and the channel loss. The difference between the nominal wavelength and the worst-case wavelength loss can be seen as a price. The optical path cost also includes transmission-related costs.
⑨The extra 1dB is for uniform downstream sending and receiving specifications.

PMD to MDI light characteristics

  The signal rate, working wavelength, side mode rejection ratio, average transmit power, extinction ratio, return loss tolerance, OMA, eye diagram, and transmitter dispersion cost (TDP) of the 10GEPON OLT transmitter are defined in Table below.

Signal rate (range)10.3125±100ppm10.3125±100ppmGBd
Wavelength (range)1575~15801575~1580nm
Side mode suppression ratio3030dB
Average transmit power (maximum)59dBm
Average transmit power (minimum)25dBm
When the transmitter is off-39-39dBm(mW)
Extinction ratio (minimum)66dB
Send OMA (minimum)3.91(2.46)6.91(4.91)dBm
Transmitter Eye Pattern Definitions X1, X2, X3, Y1, Y2, Y30.25,0.40,0.45,0.25,0.28,0.400.25,0.40,0.45,0.25,0.28,0.40UI
Optical return loss tolerance (maximum)1515dB
Transmitter reflectance (maximum)-10-10dB
Transmitter dispersion cost (maximum)1.51.5dB
Transient Dispersion Cost Dispersion Decision Time Deviation±0.05±0.05UI

The definition of 10GEPON OLT receiver’s signal rate, working wavelength, overload, sensitivity, reflectance and signal detection etc., which could be discussed in more detail if interested.

  10GEPON ONU transmitter signal rate, operating wavelength, spectrum width or side mode suppression ratio, average transmit power, extinction ratio, return loss tolerance, OMA, eye diagram and transmitter dispersion cost and other parameters so on, which could be discussed in more detail if interested.

Two-speed mode

  In 10GEPON, under the same ODN, there can be both 1GEPON ONU and 10GEPON ONU. In this case, to support the coexistence of 10GEPON ONU and 10GEPON ONU, the OLT can be set to work in a two-speed mode. To support the transmission and reception of both 10 Gbps and 1 Gbps rates, the following table describes the coexistence of PMD in the two-speed mode option.

Two-speed mode running directionOLT PMD combinationONU PMD coexisting on the same ODN
Downstream and Upstream1000BASE-PX-D

  When the downlink operates at two-speed, OLT sends 10 Gbps and 1 Gbps downlink signals simultaneously in WDM mode. When uplink is running at two speeds, OLT receives both 10 Gbps and 1 Gbps upstream signals simultaneously in TDMA mode.

Ask more 10GEPON solution cases & details!

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