Integrated Wireless-pon access Network Architectures Milos Milosavljevic

Chapter 8 Project Achievements and Future Work 
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duration defined by its bit rate divided by the number of bits per symbol. The OFDM receivers 
perform similar scale FFT and interfaced to MATLAB through for further processing.
Critically, the additive distortion of the high power amplifier (HPA) on the transmitted WiMAX 
signals is modelled in VPI. A limiter block is used for representing nonlinear transfer function 
characteristics exhibiting amplitude clipping and consequently distorting transmitted signal to 
noise ratio. Limiter amplitudes of 0.68V and -0.68V were required to achieve -31dB EVM 
figures, the maximum allowed for 64-QAM modulation in WiMAX. 
For wireless transmission, a SUI-4 wireless channel model is presented, evaluating practical 
multi-path radio signal transmission followed by BER estimation for various cycle prefixes. 
The maximum of three paths were included where a K of zero for all paths demonstrates non-
line-of-sight wireless link between the transmitter and the receiver. Finally, the channel imposes 
maximum delay and attenuation of 4 µs and 20 dB respectively on the received signal. The 
OFDM symbol duration is initially calculated and used for variance calculations by the 
CIRpowers
function that calculates variance for each path of the channel. 
Finally, once the variance for each path has been calculated the 
genh
function is then used to 
generate the Rayleigh channel coefficients according to the specific SUI type. This is achieved 
by utilising the Jakes Model to add sinusoids for generating the fading coefficients. 
Following the simulator development and individual subsystem testing, propagation evaluation 
figures were drawn to establish its transmission merits. The network design was modified from 
its preliminary set-up, accounting for a dense AWG in the OLT and a tuneable filter with a 
VCSEL array [20] in each ONU/BS to provide for efficient wavelength routing and low-cost 
colourless upstream transmission. Significantly, to account for the wireless channel degradation 
properties and distance limitations, in order to emulate the overlapping cells/sectors properties, 
the VPI/MATLAB models were revised to include noise and therefore introduce the receiver 

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