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We propose a novel reconfigurable intelligent surface (RIS) encoded information transmission scheme for a line-of-sight environment. A RIS fed with data modulates the information on impinging waves emitted from an external source in the states of polarization (SoP) of the scattered waves by performing a novel differential polarization shift keying. In particular, the information is encoded in the change of the SoP over two successive scattering slots. The proposed scheme is immune to the SoP fluctuations in the wireless channel which allows for non-coherent detection at the receiver., 5 pages, 5 figures, submitted to IEEE Wireless Communication Letters

We propose a novel binary polarization shift keying modulation scheme for a line-of-sight environment by exploiting the polarization control ability of the reconfigurable intelligent surface (RIS). The RIS encodes the information data in terms of the polarization states of either the reflected wave from the RIS or the composite wireless channel between an RF source and receiver. In the first case, polarization mismatch correction becomes essential at the receiver. In the second case, the RIS pre-codes the reflected wave to compensate for the polarization mismatch which allows non-coherent demodulation at the receiver., 5 pages, 5 figures, submitted to IEEE Wireless Communication Letters

Frequency nulling spectral precoding is an approachthat suppresses the out-of-band emission in OFDM systems.In this paper, we discuss the transmitter architecture of thespectrally precoded OFDM systems. We design a novel precoderthat matches the practical implementation of the OFDM modulator.We show that spectral precoding can relax the analog lowpass filtering requirements of the OFDM system transmitter. Weexamine the effect of spectral precoding on the PAPR as wellas the effect of the PA on the spectral precoding suppressionperformance. We also study the compliance of the spectrallyprecoded OFDM transmitter with the 3GPP standardizationmeasures and analyze its computation complexity. At the receiverside, we analyze the in-band interference and BER performanceof the suggested precoding approach. Validerad;2018;Nivå 2;2018-08-08 (rokbeg)

We consider spectrally-precoded OFDM waveforms for 5G wideband transmission in sub-6GHz band. In this densely packed spectrum, a low out-of-band (OOB) waveform is a critical 5G component to achieve the promised high spectral efficiency. By precoding data symbols before OFDM modulation, it is possible to achieve extremely low out-of-band emission with very sharp spectrum transition enabling an efficient and flexible usage of frequency resources. Spectrally-precoded OFDM shows promising results for reaching 5G targets in high-data rate enhanced mobile broadband and ultra-reliable low-latency communications use cases. Spectral precoding is particularly efficient for wideband transmission enabling short-time transmission, which will often require flexible fragmented spectrum usage., Comment: 12 pages, 6 figures

Deliverable D4.1 del projecte Europeu FARAMIR (248351) We describe herein the envisioned improvements of the REMs due to advanced sensing and processing. In relation to that, we also discuss the underlying modelling assumptions. Finally, we comment on how REMs can be of use in different scenarios as established in WP2.

Deliverable D3.1 del projecte Europeu FARAMIR (248351) El document és Confidencial al projecte europeu FARAMIR, pel que no es pot publicar el seu contingut a E-prints.

In this paper we discuss three signal models and respective Maximum Likelihood estimators of time and frequency osets. We consider implementation structures for these estimators. Furthermore, we discuss the applicability of these estimators and some variants in a proposal for the future UMTS. Godkänd; 1997; 20080506 (ysko)

This document gives an overview of Telias OFDM based proposal for UTRA and should be cinsidered as an input to the OFDM concept group within SMG 2. The document describes the fundamental frame structure, principles of the detection, modulation, coding and synchronization. Further, the channel structure, the resource management and handover principles are outlined Godkänd; 1997; Bibliografisk uppgift: ETSI STC SMG2 meeting no 22, Bad Aibling, Germany, May 1997; 20080221 (ysko)

In this paper, we present a data-based method for simultaneous Maximum Likelihood (ML) symbol timing and carrier-frequency offset estimation in Orthogonal frequency-division multiplexing (OFDM) systems. The cyclic extension, a guardspace preceding OFDM frames, is of decisive importance for this method. It is shown that the redundancy introduced by this cyclic extension allows the estimation to be performed without additional pilots. Simulations show that the performance of the frequency estimator is usable in a tracking mode while the timing estimation can be used in an acquisition mode. Godkänd; 1996; 20080220 (ysko)

This thesis deals with the estimation of synchronization parameters in {Orthogonal Frequency Division Multiplexing} (OFDM) communication systems and in active ultrasonic measuring systems. Estimation methods for the timing and frequency offset and for the attenuation taps of the frequency selective channel are presented and investigated.In OFDM communication systems the estimation of the timing offset of the transmitted data frame is one important parameter. This offset provides the receiver with a means of synchronizing its sampling clock to that of the transmitter. A second important parameter is the offset in the carrier frequency used by the receiver to demodulate the received signal.For OFDM systems using a cyclic prefix, the joint {Maximum Likelihood} (ML) estimation of the timing and carrier frequency offset is introduced. The redundancy introduced by the prefix is exploited optimally. This novel method is derived for a non-dispersive channel. Its performance, however, is also evaluated for a frequency-selective Rayleigh-fading radio channel. Time dispersion causes an irreducible error floor in this estimator's performance. This error floor is the limiting factor for the applicability of the timing estimator. Depending on the requirements, it may be used in either an acquisition or a tracking mode. For the frequency estimator the error floor is low enough to allow for stable frequency tracking.A low-complex variant of the timing offset estimator is presented allowing a simple implementation. This is the ML estimator, given a 2-bit representation of the received signal as the sufficient statistics. Its performance is evaluated for a frequency-selective Rayleigh-fading radio channel and for a twisted-pair copper channel. Simulations show this estimator to have a similar error floor as the full resolution ML estimator.The problem of estimating the propagation time of a signal is also of interest in active pulse echo systems, such as are used in, {\it e.g.}, radar, medical imaging, and geophysics. The {Minimum Mean Squared Error} (MMSE) estimator of arrival time is derived and investigated for an active airborne ultrasound measurement system. Besides performing better than the conventional {\it Maximum a Posteriori} (MAP) estimator, this method can be used to develop different estimators in situations where the system Signal to Noise Ratio (SNR) is unknown.Coherent multi-amplitude OFDM receivers generally need to compensate for a frequency selective channel in order to detect transmitted data symbols reliably. For this purpose, a channel equalizer needs to be fed estimates of the subchannel attenuations.The linear MMSE estimator of these attenuations is presented. Of all linear estimators, this estimator optimally makes use of the frequency correlation between the subchannel attenuations. Low-complex modified estimators are proposed and investigated. The proposed modifications cause an irreducible error floor for this estimator's performance, but simulations show that for SNR values up to 20~dB, the improvement of a modified estimator compared to the Least Squares (LS) estimator is at least 3~dB. Godkänd; 1996; 20080328 (ysko)

Deliverable D6.2 del projecte FARAMIR