FRESH-DFE: A New Structure for Interference Cancellation

Abstract

This paper proposes a new structure of decision feedback equalizer that exploits the cyclostationary properties of digitally modulated signals to mitigate interference. In the proposed structure, the forward filter of the conventional DFE is replaced by a cyclic filter. It is assumed that the desired and the interference signals use some mutually different signaling attributes, for example symbol rates, centre frequency etc. The resulting structure is evaluated in the presence of up to six strong interfering signals, a scenario that is typically found in wireless cellular systems. The proposed structure provides performance gains for some modulation formats but it reduces to the conventional DFE for other signal formats.

Reception filter impact on widely linear fresh receiver performance for SAIC/MAIC with frequency offsets

“…We deduce from (13) that y p,F M (k) is the sampled version, at time t = kT , of the output of the filter whose frequency (15) to (21) and whose input is x p,F M (t). It is composed of the WL FRESH filter w H F M ,k (f ), which reduces to a time-invariant (TI) linear filter for conventional receivers, followed by a sampling at the symbol rate, a real part capture and a decision box implementing the Viterbi algorithm, since r * k,k = r k ,k .…”

“…The second one is to analyze, both analytically and by simulations, the impact of the low-pass filtering on the performance of the extended WL FRESH receiver. Note that papers dealing with WL FRESH filtering for equalization/demodulation in presence of CCI are not so numerous and correspond to [15][16][17][18] for R signals and [19][20][21] for QR signals. However none of these papers discuss the impact of a low-pass filter on the output performance.…”

Two and three inputs widely linear FRESH receivers for cancellation of a quasi-rectilinear interference with frequency offset

“…The second one is to analyze, both analytically and by simulations, the impact of this differential FO on the performance of these two SAIC/MAIC receivers. Note that the scarce papers dealing with WL FRESH filtering for demodulation of QR signals [16][17][18] do not consider the proposed WL FRESH receivers and do not present any analysis of potential differential FO on the performance. To our knowledge, the impact of differential FO on the performance of WL receivers has been analyzed in [19] for R signals but has never been analysed for QR signals before this paper.…”

Widely linear FRESH receiver for SAIC/MAIC with frequency offsets

“…The CT approach allows us to exploit the full potential of the receiver by removing both the filtering structure constraints imposed by a discrete-time (DT) approach and the possible influence of the sampling rate. Note that while [2] introduces the basis of WL FRESH filtering for estimation purposes, WL FRESH filtering for equalization/demodulation in presence of CCI has been considered in [16][17][18][19] for R signals and in [20][21][22] for QR signals. While [18], [21] concern DS-CDMA systems, [17] considers blind processing whereas [16], [19] and [22] use DT MMSE approaches.…”