Performance

Technology differentiation

KDPOF´s technology outperforms the state of the art currently available in the market. Depending on the requirements and restrictions of each target market KDPOF´s technology adapts its behavior to deliver the highest level of performance.

In the Commercial market, delivering 1 Gbps over a maximum of 50 to 80 m is the target. KDPOF is the only market feasible technology, now also a standard, to deliver this performance.

In the Automotive Industry, next generation Infotainment and ADAS vehicle networks demand, at least, 1 Gbps for 15 m but with a challenging link power budget. Here, again, KDPOF´s technology is the only available technology that meets the stringent automotive requirements.

Finally, the Industrial networks demand lower bitrates (100 Mbps) but longer distances. Current Industry standards specify a maximum coverage of 50 m. not because the demand doesn´t require more but because before KDPOF´s market launch it was not technologically feasible reaching more than 50 m. Now, thanks to KDPOF´s technology, industry standards can be reviewed to increase the POF based networks coverage up to 150 m at 100 Mbps.

The following picture shows a summary of KDPOF´s position within the current market state of the art for each of the target markets: Commercial, Industrial and Automotive.

KDPOFPositionV2

KDPOF´s approach to the design of the communication system has been to optimize the capacity of the communication channel, which comprises not only the fiber but the optoelectronics as well. Many transmission modes were evaluated combining different modulation schemes with a plethora of symbol rates. A numerical optimization approach based on information theory led to selection of a final winning combination of 312.5 MHz symbol rate with 16-PAM modulation levels. The optimality of this “sweet spot” is shown in the following figure:

 

 

In terms of Bit Error Rate (BER) and Mean Time To False Packet Acceptance (MTTFPA), KDPOF technology ranks among Ethernet standards and fulfills the needs of a reliable channel. KDPOF´s proximity to Shannon´s limit for a typical channel is the best metric to judge the overall system performance:

 

 

 

KDPOF technology is developed around an Adaptive Bit Rate (ABR) functionality. The technology is able to continously monitor the channel and adapt in real time the link parameters to maintain the performance at the optimum level. The result is an “Always On” channel with the best performance achievable without packet loss.

The ABR functionality has two modes of operations: 1 Gbps and 100 Mbps. The Bit Rate adaptation takes place around each central set point always searching for the best optimum performance. The following graph shows the ABR functionality operation scheme for each of the operating modes. In this case the link is adapted in real time, based on the length of the physical channel, reducing the link speed as the channel grows in length. If instead of a length change another link parameter is modified (attenuation, bending, temperature, etc.) the system will behave identically always searching for the best performing system for the actual conditions. And all these without a single packet loss.

ABRPerformance

Link Budget

Link budget is a key figure of merit to judge the goodness  of a communication technology. For an optical link like KDPOF´s target, the link power budget is established between test points 2 and 3 of the following figure. In accordance with this convention, the power margin is calculated in dBo for a 10-12 BERtaking into account the minimum outuput power at TP2 and the worst case sensitivity at TP3. For a typical duplex channel of 15m length, a 1 Gbps link can be established with an optical power margin of 13.7 dBo. The system chooses the optimal operation point of 16 PAM with 312.5 MS/s and spectral efficiency of 3.3145 bits/Symbol:

 

 

If the link speed is reduced to 100 Mbps, the link power margin increases to 26.8 dBo. The optimum performance in this case requires a 4-PAM modulation with a sample frequency of 62.5 MS/s and a spectral efficiency of 1.8145 bits/symbol  as can be seen in the following figure:

 

Energy Efficient Ethernet

KDPOF technology implements Energy Efficient Ethernet (EEE), which translates into an optimum performance in terms of power consumption of the overall communication system. The following figure shows the EEE performance for different link loads. For comparison, the 1000BASE-T EEE performance is shown. Our EEE implementation is clearly superior to its 1G BASE-T benchmark:

Energy Savings comparison for typical 6oo Bytes frame Poison arrivals
Measurements shown in the figure have been determined using standard Ethernet traffic validation systems including:
  • Spirent Ethernet Test Center
  • RFC 2544 “Benchmarking Methodology for Network Interconnect Devices”
  • Reported speed are for “true” physical bitrates
  • Proper False Pause Frames Generation for Flow control

Measures were taken at the KDPOF and independent laboratory premises:

  • Temperature range:  -45ºC to +85ºC
  • Temperature cycles: Fast (>20 ºC/s) and slow to check the tracking algorithms
  • Induced non linearity changes: verified they get compensated in real-time