ICI Cancellation Technique based on Estimating Delay and Doppler Profile in OFDM Reception.

A Low-Complexity Turbo Equalizer for OFDM Communication Systems

“…A number of methods have been developed to reduce this ICI sensitivity to a frequency offset [1], [6]- [10], including the windowing of the transmitted signal [7], the use of ICI self-cancellation schemes [8], [9] and the use of the channel matrix inversion for ICI cancellation [10]. Although all these approaches are effective in many practical applications (HDTV, WLAN, WiFi, WiMAX), minimizing the effect of ICI in this way is inherently suboptimal because interference contains information about the symbols that have been transmitted.…”

“…Therefore we assumed that the transmission channel consists of N P differently Doppler-shifted propagation paths with incident angles γ i . In fact, difference in incident angles γ i for each transmission path defines the difference in the Doppler shifts [10]. Thus, the received OFDM signal can be written as:…”

Improving of channel estimation scheme in mobile reception of OFDM

“…However, it is necessary to estimate the channel transfer function when ICI canceller is performed. The channel estimation scheme under the Doppler-spread channel has been proposed [2,3]. However, when number of path is increased, accuracy of the conventional channel estimation scheme is not enough to remove the influence of ICI.…”

Improving Mobility in Wireless MAN

“…Therefore, for the subchannel P(DO, = +I/ y0Q)) of interest: P(D = -1/y (t)7 (6) As was mentioned above, the specific realization of P(S(t)/yO(t)) =P P(DO /YO (7) P(D+1 / YO(t)). * (D+MJ2 / YO(t) The signal dependence of Di can be removed in equation (7) by averaging P(DO = ±I/ yo (t)) over all the possible values of the information symbols Di as: 2P -( P(Do= -1 Y(to)) k F EP(Si IYo W)) L L i~~=2' I-J Figure 5 shows the structure of a proposed turbo equalizer that implements logs form of equation 8 during making decision (6) about sign of the transmitted informational symbol DO.…”

“…This assumption allowed us to use a simple model of ICI in a DMT-based system. A number of methods have been developed to reduce this ICI sensitivity to a frequency offset [2][3][4][5][6][7][8], including the windowing of the transmitted signal, DFE implementation, implementation of ICI self-cancellation schemes and use the channel matrix inversion [7]. Although all these approaches are effective in many practical applications (HDTV, WLAN, Wi-Fi), minimizing the effect of ICI in this way is inherently suboptimal because interference contains information about the symbols that have been transmitted.…”