WIMAX TESTBED

WiMAX, the Worldwide Interoperability for Microwave Access, is a
telecommunications technology aimed at providing wireless data over long distances
in a variety of ways, from point-to-point links to full mobile cellular type access. It is
based on the IEEE 802.16 standard, which is also called Wire IessMAN. The name
WiMAX was created by the WiMAX Forum, which was formed in June 2001 to
promote conformance and interoperability of the standard. The forum describes
WiMAX as a standards-based technology enabling the delivery of last mile wireless
broadband access as an alternative to cable and DSL. This Final Year Project attempts
to simulate via Simulink, the working mechanism of a WiMAX testbed that includes
a transmitter, channel and receiver. This undertaking will involve the baseband
physical radio link. Rayleigh channel model together with frequency and timing
offsets are introduced to the system and a blind receiver will attempt to correct these
offsets and provide channel equalization. The testbed will use the Double Sliding
Window for timing offset synchronization and the Schmid! & Cox algorithm for
Fractional Frequency Offset estimation. The Integer Frequency Offset
synchronization is achieved via correlation of the incoming preamble with its local
copy whereas Residual Carrier Fr~quency Offset is estimated using the L th extension
method. A linear Channel Estimator is added and combined with all the other blocks
to form the testbed. From the results, this testbed matches the standard requirements
for the BER when SNR is 18dB or higher. At these SNRs, the receiver side of the
testbed is successful in performing the required synchronization and obtaining the
same data sent. Sending data with SNR lower than 18dB compromises its
performance as the channel equalizer is non-linear. This project also takes the first
few steps of hardware implementation by using Real Time Workshop to convert the
Simulink model into C codes which run outside MATLAB. In addition, the Double
Sliding Window and Schmid! & Cox blocks are converted to Xilinx blocks and
proven to be working like their Simulink counterparts.