Angol
High speed digital communications has widely used Orthogonal Frequency Division Multiplexing during last three decades. The OFDM implementation initial obstacles are many, such as high speed memory and massive complex computation, due to the Very Large Scale Integrated circuit (VLSI) and Digital Signal Processing (DSP) that marked as an effective technologies . Meantime, the employment of Fast Fourier Transform declines coherent demodulation and sinusoidal generators arrays and makes the cost of implementation of the technology productive. Additional cause for the popularity of OFDM is theoretically proved with its optimal performance. OFDM signals transmitted through multiple subcarriers which mean that OFDM is considered as a multicarrier modulation. OFDM subcarriers have the property of the orthogonality and they operate at different frequencies. OFDM has been applied in wireless and wired communications, such as Digital Audio Broadcast (DAB), IEEE (Institute of Electrical and Electronics Engineers) 802.11a/g and IEEE 802.16a . A frequency-selective channel is transformed through OFDM to a parallel set of frequencies .
