This paper depicts the development of Orthogonal Frequency Division Multiplexing from a historical perspective. A summary of major research milestones are noted that contributed to modern-day OFDM.These contributions include the use of discrete Fourier transforms replacing the analog implementation and addition of cyclic extensions to ensure orthogonality among the sub-channels. Also, channel equalization algorithms to suppress inter-symbol interference and inter-carrier interference, channel estimation through the insertion of pilot tones among data blocks, peak-to-average power ratio reduction, and synchronization techniques are discussed.This full text paper was peer reviewed at the direction of IEEE Communications Society subject matter experts for publication in the IEEE "GLOBECOM" 2008 proceedings.978-1-4244-2324-8/08/$25.00

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This paper presents an evaluation of a deployed WiMAX system operating in the 4.9GHz Public Safety Band in the City of Tulsa. The study includes propagation analysis for the coverage and network performance tests to demonstrate the viability of a WiMAX system as a medium for public safety. We considered existing propagation models in the UHF band (300 MHz to 3 GHz) to be applied to 4.9 GHz and compared the characteristics predicted by the models with the measured data. The results show that of the three models presented, the Cost-231 Hata Model best predicts the characteristics of the deployed WiMAX system.Network performance tests were also conducted to measure the throughput of the system at various adaptive modulation rates.