A simple iterative interference cancellation scheme for orthogonal frequency division multiplexing (OFDM) signals with blanking nonlinearity in impulsive noise channels is presented. Blanking nonlinearity has been widely used in practical OFDM systems to suppress impulsive noises at the expense of reducing signal power and generating intercarrier interference (ICI). To improve the performance of blanking nonlinearity element, we propose an iterative interference cancellation scheme which can effectively reduce the level of ICI caused by the blanking operation at the OFDM receiver. With adaptive blanking threshold for each iteration, the proposed iterative receiver design can converge to its best performance with only three iterations. Simulation results show significant performance improvement is achieved by the proposed scheme.

Iterative Interference Cancellation for OFDM Signals With Blanking Nonlinearity in Impulsive Noise Channels

The detriment arising from strong and frequently occurring impulses over an Orthogonal Frequency Division Multiplexing system is paramount because signals on sub-carriers appear to be corrupted simultaneously. To overcome this obstacle, clipping has been reported as an effective approach. Unlike previous works, this work derived the clipping threshold without assuming the a priori knowledge of the probability density function (PDF) of impulsive noise, which is usually unobtainable in precise measure in most practical scenarios, and may change rapidly over time. Then, a decoding metric accommodated to the clipping effect was derived to realize coding gain. To attest the proposed scheme, this study conducted computer simulations in compliance with the IEEE 1901 standard. For various impulse noise models under consideration, the proposed scheme was promisingly on par with its conventional counterpart, the clipping threshold of which, however, relies on an assumed PDF.

Robust Clipping for OFDM Transmissions over Memoryless Impulsive Noise Channels

A method of signal processing according to one of several embodiments includes estimating a deterministic component of a received signal. The estimating is based on an estimated response of a transmission channel. Based on the estimated deterministic component, a non-deterministic component of the received signal is estimated. Based on corrupted portions of the estimated non-deterministic component, a noise estimate is obtained, and the received signal is compensated based on the noise estimate. A method according to another embodiment includes replacing received samples at corrupted locations with values from a calculated model.

Systems, methods, and apparatus for impulse noise mitigation

Impulse noise is a significant problem in some OFDM applications, including digital television broadcasting. In this paper, we study a novel decision directed impulse mitigation algorithm, both analytically and with simulations for the DVB-T parameters. In this algorithm, the noise component in each received input sample is estimated based on preliminary decisions on the transmitted data. When the estimate is large enough to indicate that impulse noise is present in the sample, the estimated noise component is subtracted from the input sample before final demodulation. This technique has been shown to be extremely effective in flat fading channels. In this paper, its application in frequency selective fading channels is analyzed. The optimum weighting factors for combining noise estimates from subcarriers subject to different fading are calculated. Simulation results are presented for Rayleigh and Ricean channels which show that the technique can reduce the error rates due to impulsive noise by an order of magnitude.

Decision directed impulse noise mitigation for OFDM in frequency selective fading channels [DVB-T example]

The development of power line communication systems for broadband multimedia applications requires a comprehensive knowledge of the channel characteristics and the main peculiarities that may influence the communication over this channel. PLC

Techniques for broadband power line communications: impulsive noise mitigation and adaptive modulation

The paper describes a new technique for mitigating the effects of impulse noise in OFDM. An estimate is made of the noise component in each received input sample. The estimates are based on the transmitted data. No pilot tones are required. When the estimate is large enough to indicate that impulse noise is present in the sample, the estimated noise component is subtracted from the input sample before final demodulation. Estimates of the noise are obtained from preliminary decisions based on the noisy signal. The technique is effective because the energy from each noise impulse is spread across the received spectrum. The technique can also be applied to multicarrier CDMA. Simulations show that, in cases of practical importance, the symbol error rate can be reduced by several orders of magnitude.

H.A. Suraweera

Papers

Impulse noise mitigation for OFDM using decision directed noise estimation