Integrated Wireless-pon access Network Architectures Milos Milosavljevic

Figure 5-4: Optical network unit/base station modeling 
Table 5-5: DFB laser parameters in the ONU/B
S
Parameter 
Value 
Unit 
Emission Frequency 
2.9979e8/1310e-9 
Hz 
Average Power 
3 
mW 
Laser Chip Length 
100e-6 
m 
Active Region Width 
3e-6 
m 
Photon Lifetime 
3 
ps 
Carrier Lifetime 
2.1 
ps
Differential Refractive 
Index 
-1.63e-26 
m^3 
LineWidth 
Enhancement Factor 
3 
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Chapter 5 Interoperability of xPON and WiMAX 
99 
The laser driver circuit, with the parameters given in Table 5-6, is utilised to bias the laser to 
produce the required power as well as to set the correct amplitude of the input signal avoiding 
clipping at the laser output. 
Table 5-6: Laser driver parameters
 
Parameter 
Value 
Unit 
Drive Amplitude 
800e-6 
V 
Bias 
21e-3 
V 
The electrical BPFs, before the HPAs, are used to select the desired channel prior to 
transmission over the air. The local oscillator is running in synchronism with the OLT oscillator 
for the specific ONU/BS. 
The ONU/BS will be modified at a later stage to include VCSEL array and tuneable optical 
BPF operation for enhanced network dynamicity by the use of multiple wavelengths. This 
topology will be investigated in the following chapter. In contrast, the ONU/BS design 
presented here is adequate for establishing and evaluating transparent WiMAX transmission 
over legacy TDM PONs.
5.2.3 Optical Outside Plant Simulation 
The outside plant consists mainly of a passive splitter and a SSMF as in typical PON 
deployments. The passive splitter is modelled with the variable optical attenuator to account for 
various split losses while the 20 km SSMF is modelled using a standard universal fibre VPI 
module, featuring bidirectional signal flow, nonlinearities, various dispersion effects and loss 
figures [22].
The VPI Table 5-7 includes the modelling parameters for the 20 km SSMF. A standard 
chromatic dispersion parameter was utilised to represent a typical fibre.
Since, the optical power 

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