A rank-reduced LMMSE canceller for narrowband interference suppression in OFDM-based systems

Abstract

Abstract-We present a narrowband interference (NBI) canceller that suppresses spectral leakage in an orthogonal frequency-division multiplexing (OFDM)-based system caused by a narrowband (NB) signal. In our scenario, we assume that the spectrum of the NB signal is within the spectrum of the OFDM signal. This can be the case, e.g., on digital subscriber lines (DSL) and in new unlicensed frequency bands for radio transmission.The canceller makes linear minimum mean-square error estimates of the spectral leakage by measuring the NBI on a few modulated or unmodulated OFDM subcarriers. It uses a model of the NB signal's power spectral density as a priori information. Using frequency invariant design it is possible to cancel NBI from signals that are changing their frequency location with significantly reduced complexity overhead. The operational complexity of the canceller can be lowered by using the theory of optimal rank reduction and using the time-bandwidth product of the NB signal.Analytical performance evaluations, as well as Monte Carlo simulations, also show that without perfect a priori information this canceller can suppress the spectral leakage from a strong NB signal (e.g., with equal power as the OFDM signal) to well below the background noise floor for typical applications where it causes negligible signal to noise ratio and symbol error rate degradation.Index Terms-Digital subscriber lines (DSL), discrete multitone (DMT), industrial-scientific-medical (ISM) band, orthogonal frequency-division multiplexing (OFDM), radio frequency interference (RFI), wireless local area network (WLAN).

A Sparsity-Aware Approach for NBI Estimation in MIMO-OFDM

“…20 known subcarriers out of 128 total subcarriers in each OFDM symbol. In the same figure, we show the performances of two other approaches from the literature; namely, the LMMSE and CMMOE approaches proposed in [8] and [9], respectively. We provided both approaches with the exact auto-correlation matrix of the NBI signal which Performance comparison between CS, LMMSE, and CMMOE approaches for SISO CP-OFDM systems with the HT 40MHz mode for r = 3. involved the profile of the fading channel experienced by the NBI, the FO distribution, and the transmitted NBI vector.…”

“…In [8], a few silent (unmodulated) subcarriers are used to measure the interference signal and, then, the linear minimum mean square error (LMMSE) technique is used to estimate the whole NBI signal. The constrained minimum mean-outputenergy (CMMOE) is proposed in [9] for NBI suppression where the receiver is designed to minimize the output energy while preserving the desired symbol and canceling the intercarrier interference.…”

Applying spatial diversity to mitigate partial band interference in undersea networks

“…The interference mitigation techniques typically exploit the short time or limited frequency span of the interfering signal. Examples of impulsive noise suppression techniques for multi-carrier modulation may be found in [25]- [31], while [32]- [41] address narrowband interference mitigation. Early approaches tended to separate channel estimation and interference detection, and more recent work has focused on jointly estimating the channel and mitigating interference.…”

A Comparison of a Single Receiver and a Multi-Receiver Techniques to Mitigate Partial Band Interference

“…The interference mitigation techniques typically exploit the short time or limited frequency span of the interfering signal. Examples of impulsive noise suppression techniques for multi-carrier modulation may be found in [5]- [11], while [12]- [21] address narrowband interference mitigation. Early approaches tended to separate channel estimation and interference detection, while more recent work has focused on jointly estimating the channel and mitigating interference.…”