Integrated Wireless-pon access Network Architectures Milos Milosavljevic

Figure 7-6: Obtained EVM at the WiMAX OLT receiver for 3.5 GHz channel
The resemblance of experimental and simulation results, in relation to EVM, confirm that 
network modelling, in view of the rigid selection of its design parameters, can approximate an 
equivalent experimental test-bed with accuracy. Therefore, it can be concluded, that the 
proposed optical network provides a transparent channel for standard wireless signal formats 
transmitted bi-directionally over a multi-wavelength power-splitting PON.

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Chapter 7 Experimental Investigation of WiMAX Transmission over Multi-Wavelength PONs 
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Finally, the constellation diagrams obtained at the WiMAX receivers after 23.2 km fibre and 16 
split are displayed in Figure 7-7. The RF drive power in the MZM was +13 dBm and -6 dBm 
for downstream and upstream respectively since these powers are considered optimum for the 
lowest received EVM. It is important to note that no phase rotations could be observed since the 
constellation diagrams are obtained after the amplitude and phase correction, in contrast to the 
simulation results presented in the previous chapter. The two outermost points on the 
constellations are the pilot tones used for synchronisation and estimation purposes. 
Figure 7-7: 64-QAM Downstream (left) and 16-QAM upstream (right) modulation

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Chapter 7 Experimental Investigation of WiMAX Transmission over Multi-Wavelength PONs 
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7.4 Summary
This chapter summarised the performance figures produced by the experimental demonstration 
of WiMAX transmission over legacy PONs and their resemblance to the modelling results 
presented in proceeding chapters. This was achieved by the application of the Aeroflex PXI 
IEEE802.16-2005 WiMAX transceivers, terminated at the OLT and ONU/BSs of the multi-
wavelength PON with the aim of substantiating the simulation results that recommended the 
feasibility and performance validity of the original network architecture.
To demonstrate fixed-to-mobile convergence, a BER of 1E-9 has been initially demonstrated 
for wired users, featuring error-free GPON transmission by means of FDM propagation over 
multi-wavelength, power-splitting links.
In addition, experimental results have confirmed EVM figures, at remote base stations and the 
OLT receiver, below -29 dB and -23 dB for 25.2 Mbit/s and 18.9 Mbit/s, downstream and 
upstream WiMAX channels respectively, being in compliance with IEEE 802.16-2005 
standards. Higher data rates however could be achieved with wider WiMAX bandwidths. 
Significantly, 40 km downstream transmission without any dispersion compensation was also 
readily achieved.
Finally, direct VCSEL laser modulation in upstream has shown negligible degradation on the 
received WiMAX channels in the OLT demonstrating low-cost colourless ONU/BS termination 
with simple couple optics.

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