Integrated Wireless-pon access Network Architectures Milos Milosavljevic

PONs with Overlapping Cells 
the obtained transmission 
comparable AWG passband characteristics with 
modeling
a tunable optical band-pass filter with 50 
wavelength which is then detected by an APD followed 
transmitted WiMAX channels.
filtered with a 100 MHz BPF, 
linear high gain amplifier and transmitted over AWGN, multi-path SUI-4 
For the faded wireless path the cyclic prefix of 1/4 is included to reduce 
The subscriber receiver is allocated in the overlapping region 

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Chapter 6 Multi-Wavelength WiMAX-PONs with Overlapping Cells 
125 
Figure 6-6: Modified ONU/BS to account for multi-wavelength transmission
The two upstream WiMAX channels at 3.4 GHz and 3.5 GHz originating at the overlapping 
sector are received by ONU/BS2 and ONU/BS9 respectively and are directly modulated in a 6 
mW biased, +1.2 dBm [5] VCSEL array each at 
λ
u
1
=1553.33
nm and 
λ
u
1
=1554.13 nm 
respectively. The VCSEL parameters are given in Table 6-3. A threshold current of 0.75mA and 
1.5 mW thermal rollover power are specified according to the model in [5]. The laser is 
assumed to be operated at the ambient temperatures for which the bias current versus output 
power (L-I) characteristics are given in Figure 6-5 (left). Other physical parameters of the laser 
such as the core radius, active region thickness, and spontaneous recombination rate are 
adjusted to comply with a typical device data sheet. To that extent, the obtained transfer 
function of the laser is given in Figure 6-7 (right). 

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Chapter 6 Multi
Parameter
Emission Frequency
Average Power
Core Radius
Active Region 
Thickness
Spontaneous 
Recombination 
Carrier Lifetime
LineWidth 
Enhancement Factor
Threshold Current
Thermal Rollover Power
Thermal Rollover 
Current
Figure 6
As it could be observed from the figure 
device in terms of L-I curve
the thermal roll over current, starts to drop due to the thermal behavior of the laser
Finally, the upstream WiMAX channels
maximum data rate of 40 Mbit
to drive the VCSEL laser array. Consequently, due