Bit Error Rate of IEEE 802.16 OFDM Physical Layer using (I)FFT Block with Fixed-Point Arithmetic

Hossam Fattah


WiMAX, IEEE 802.16, Protocols and Standards, OFDM, Hardware


IEEE 802.16 wireless networks, known as WiMAX, employ Orthogonal Frequency Division Multiple (OFDM) access scheme as one of its robust physical layer schemes. The OFDM physical layer employs (Inverse) Fast Fourier Transform (I)FFT for converting the input bit stream from time domain to frequency domain or vice-versa. This (I)FFT block is a crucial component in both the transmit and receive path since it involves extensive arithmetic operations. The accuracy and performance of such operations can be greatly effected when these operations are performed as fixed-point operations where a finite number of bits can be used for storing the intermediate and final results of the (I)FFT. Performance of the OFDM transceiver, in terms of the bit error rate when using fixed-point calculations, is of a great interest for realistic deployment of such an OFDM transceiver in hardware platforms or many wireless devices. In this paper, we study the performance of an OFDM transceiver when using a fixed-point (I)FFT and compare it to the ideal case of using floating point operations. In addition, we consider the transmit and receive paths of an OFDM transceiver according to the technical specifications as outlined by the IEEE 802.16 standard. Simulation results demonstrate the bit error rate performance of a practical OFDM-based IEEE 802.16 transceiver when the (I)FFT block is using a finite number of bits

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