AN 846: Intel® Stratix® 10 Forward Error Correction

ID 683805
Date 7/02/2018
Public
Document Table of Contents

5.3.1. 100GBASE-KP4 Mapping (IEEE802.3bj Clause 91)

Figure 18. 100GBASE-KP4 Mapping
  • RS (544, 514, 15, 10) FEC
  • 26.5625 Gbps
  • 3.03% rate expansion
  • Data is stripped per symbol across four lanes

RS(544, 514) requires additional room to accommodate 5440 bits instead of 5280 bits. After transcoding, it must additionally make room for approximately 3% more bits of overhead. The precise overhead is calculated as 1/33; new rate = old rate * 34/33. This result is overspeed for PAM4. For example:

  • Payload data rate = 50 Gbps
  • Encoding it to 66b encoding: 50*66/64 = 51.5625 Gbps
  • Adding FEC expansion: 51.5625*(34/33) = 53.125 Gbps

Intel® Stratix® 10TX devices do not support the 100GBASE-KP4 physical medium dependent (PMD).

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