OFDMA_Part8 - E5. Due to the definitions given in equation...

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8 section 2.4 for more information). Once the CP has been added, the parallel-to-serial converter transforms { x CP + OFDM } into a sequence of ( N + α ) time-domain symbols. These symbols are then passed through a Digital-to- Analog Converter (DAC) to provide the baseband signal. This signal is then up-converted to the carrier frequency f c and transmitted out of the antenna. The signal then travels through the wireless channel (let the channel’s impulse response be designated by h ) to the RX. As shown in the OFDM receiver of Figure 3, the received signal is first down-converted to baseband and filtered to remove any high frequency components. The Analog-to-Digital Converter (ADC) samples the resulting signal to obtain: y [ n ] = h [ n ] x CP + OFDM [ n ] + noise where n ( N 1) …(E5) For simplicity, assume that there is no noise in equation
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Unformatted text preview: E5. Due to the definitions given in equation E3, each time-domain symbol constituting { x CP + OFDM } has the following interesting property: x [ m k ] = x [( m k )% N ] where m ( N 1) and k (E6) where % represents the modulo operation. This property makes { x CP + OFDM } circularly symmetric. As a result, the convolution between the channel h and { x CP+OFDM } can be written in the form of circular convolution in the following way: y [ m ] = h [ l ] x [ m l ] l = L 1 where m ( N 1) (E7) y [ m ] = h [ l ] x [( m l )% N ] l = L 1 y [ m ] = h [ m ] x [ m ] (E8) Y [ k ] = H [ k ] X [ k ] (E9)...
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This note was uploaded on 09/27/2009 for the course ECE 399 taught by Professor Prof during the Spring '09 term at University of Texas at Austin.

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