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R Reggiannini - One of the best experts on this subject based on the ideXlab platform.
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low complexity blind Carrier Frequency recovery for ofdm signals over Frequency selective radio channels
IEEE Transactions on Communications, 2002Co-Authors: Marco Luise, M Marselli, R ReggianniniAbstract:This paper introduces a blind (i.e., data independent) algorithm for Carrier Frequency offset recovery in an orthogonal Frequency-division multiplexing (OFDM) receiver operating over Frequency-selective fading channels. The main idea behind this algorithm is to exploit the time-Frequency-domain exchange inherent to the modulation scheme. Due to this feature, a Carrier Frequency offset has a similar impact on OFDM as a clock timing offset has in a quadrature amplitude modulation (QAM) system. The scheme we propose is a variant of Oerder-Meyr's (1988) feedforward clock recovery. Its performance is assessed by simulation, and the results are compared to those obtained from Van de Beek-Sandell-Borjesson's (1997) Frequency synchronizer, which bears comparable complexity. The new scheme is shown to outperform the latter over Frequency-selective fading channels, notably at medium to high signal-to-noise ratios. We also evaluated the efficiency of two different (time domain and Frequency domain) offset correction strategies embedded in a particular OFDM receiver.
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Carrier Frequency recovery in all digital modems for burst mode transmissions
IEEE Transactions on Communications, 1995Co-Authors: Marco Luise, R ReggianniniAbstract:Reliable data detection in time division multiple access (TDMA) communication systems strictly depends on the availability of accurate estimates of the synchronization parameters of the received signal, i.e., Carrier Frequency/phase and symbol timing, which must be derived from the burst preamble. The authors focus on the Carrier Frequency estimation aspect, and present a fast, open-loop, all-digital Frequency offset estimation technique, whose performance is assessed in two different communication scenarios: a TDMA satellite link employing standard modulation and burst formats, and a mobile cellular terrestrial radio system with signal and channel characteristics obeying the pan-European Group Special Mobile (GSM) recommendations. The use of the algorithm as a Frequency error detector (discriminator) in a recursive ("closed-loop") Frequency offset estimator is also discussed, and some results concerning both the transient and the steady-state behavior of such a scheme are presented. Finally, the impact of the algorithm on the receiver BER is briefly analyzed. >
Marco Luise - One of the best experts on this subject based on the ideXlab platform.
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blind Carrier Frequency tracking for filterbank multiCarrier wireless communications
IEEE Transactions on Communications, 2005Co-Authors: Vincenzo Lottici, Marco Luise, C Saccomando, F SpallaAbstract:Filterbank multiCarrier modulation (FBMCM) is an attractive technology for high-speed twisted-pair transmission and for broadband wireless communications, as well. In wireline applications, signal transmission takes place at baseband, so the issue of Carrier acquisition and tracking for coherent demodulation does not apply. In wireless communications, on the contrary, Carrier-Frequency recovery reveals the Achille's heel of multiCarrier modulation, so that robust signal processing algorithms are needed in this respect. In this paper, we derive a nondata-aided Carrier-Frequency offset recovery method for wireless FBMCM modems. In particular, we illustrate how to derive a low-complexity closed-loop tracker starting from a maximum-likelihood approach. We then show that the proposed simplifications do not entail large performance losses. In this respect, we derive the standard performance metrics of a closed-loop tracker (S-curve, root mean square estimation error, acquisition time) both on the additive white Gaussian noise channel and on a typical static Frequency-selective wireless channel. We also demonstrate by simulation good robustness of the Frequency tracker with respect to FBMCM symbol-timing errors.
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low complexity blind Carrier Frequency recovery for ofdm signals over Frequency selective radio channels
IEEE Transactions on Communications, 2002Co-Authors: Marco Luise, M Marselli, R ReggianniniAbstract:This paper introduces a blind (i.e., data independent) algorithm for Carrier Frequency offset recovery in an orthogonal Frequency-division multiplexing (OFDM) receiver operating over Frequency-selective fading channels. The main idea behind this algorithm is to exploit the time-Frequency-domain exchange inherent to the modulation scheme. Due to this feature, a Carrier Frequency offset has a similar impact on OFDM as a clock timing offset has in a quadrature amplitude modulation (QAM) system. The scheme we propose is a variant of Oerder-Meyr's (1988) feedforward clock recovery. Its performance is assessed by simulation, and the results are compared to those obtained from Van de Beek-Sandell-Borjesson's (1997) Frequency synchronizer, which bears comparable complexity. The new scheme is shown to outperform the latter over Frequency-selective fading channels, notably at medium to high signal-to-noise ratios. We also evaluated the efficiency of two different (time domain and Frequency domain) offset correction strategies embedded in a particular OFDM receiver.
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Carrier Frequency recovery in all digital modems for burst mode transmissions
IEEE Transactions on Communications, 1995Co-Authors: Marco Luise, R ReggianniniAbstract:Reliable data detection in time division multiple access (TDMA) communication systems strictly depends on the availability of accurate estimates of the synchronization parameters of the received signal, i.e., Carrier Frequency/phase and symbol timing, which must be derived from the burst preamble. The authors focus on the Carrier Frequency estimation aspect, and present a fast, open-loop, all-digital Frequency offset estimation technique, whose performance is assessed in two different communication scenarios: a TDMA satellite link employing standard modulation and burst formats, and a mobile cellular terrestrial radio system with signal and channel characteristics obeying the pan-European Group Special Mobile (GSM) recommendations. The use of the algorithm as a Frequency error detector (discriminator) in a recursive ("closed-loop") Frequency offset estimator is also discussed, and some results concerning both the transient and the steady-state behavior of such a scheme are presented. Finally, the impact of the algorithm on the receiver BER is briefly analyzed. >
Aria Nosratinia - One of the best experts on this subject based on the ideXlab platform.
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performance of mimo single Carrier Frequency domain zero forcing equalizer
International Symposium on Information Theory, 2012Co-Authors: Ahmed Hesham Mehana, Aria NosratiniaAbstract:Single-Carrier Frequency domain equalization (SC-FDE) has many advantages, but in the MIMO Frequency selective channel its performance has not been fully characterized and several important open questions remain. This paper analyzes the diversity of zero-forcing MIMO SC-FDE. It is shown that the diversity of the ZF receiver over this channel is the same as that of the ZF receiver in the Frequency-flat channel. To improve the performance, a lattice-reduction (LR) aided ZF equalization is proposed and analyzed. It is shown that the full spatial and temporal diversity is achieved by he LR-aided ZF receiver for the uncoded transmission. This is the first analytical proof for the LR-aided equalization for MIMO Frequency selective channel.
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diversity order of mmse single Carrier Frequency domain linear equalization
Global Communications Conference, 2007Co-Authors: Ali Tajer, Aria NosratiniaAbstract:In this paper we investigate the diversity order of single-Carrier Frequency domain equalizers (SC-FDE). Specifically, we look at minimum mean square error (MMSE) linear equalizers utilizing block-transmission and cyclic prefix. It is shown that the diversity order in these systems depends on data transmission rate, channel memory length, as well as transmission block length. Analyses reveal that with memory length v and transmission block length L, for the rates Rleslog L/v full diversity of v+1 is achievable. For higher rates the achievable diversity order is degraded and is equal to [2-R L]+1. Therefore MMSE SC-FDE has a diversity that varies between 1 and v+1, and achieves full diversity only for a limited range of data rates.
G L Stuber - One of the best experts on this subject based on the ideXlab platform.
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joint estimation of Carrier Frequency and sampling Frequency offsets for sc fde systems on multipath fading channels
IEEE Transactions on Communications, 2008Co-Authors: Pinghung Chiang, Dingbing Lin, G L StuberAbstract:With single-Carrier Frequency-domain equalization, the Carrier-Frequency and sampling-Frequency offsets are embedded in the phases of complex Frequency-domain signal components. This paper proposes a sub-block processing to extract the phases and applies the least-squares regression to jointly estimate the offsets. The effectiveness of the proposed SC-FDE receiver is demonstrated on multipath fading channels.
Wookwon Lee - One of the best experts on this subject based on the ideXlab platform.
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Carrier Frequency offset estimation for ofdm systems with null subCarriers
IEEE Transactions on Vehicular Technology, 2006Co-Authors: Jie Zhu, Wookwon LeeAbstract:An accurate estimation of Carrier Frequency offset (CFO) is a crucial task for orthogonal Frequency-division multiplexing (OFDM) systems but should be performed with affordable computational complexity for practicality. In this paper, the authors derive two new estimation algorithms (one for the integer part and the other for the fractional part of CFO), each of which utilizes only one OFDM block with null subCarriers but offers improved accuracy and reduced complexity. The proposed estimator for fractional CFOs operates iteratively and is insensitive to the initial CFO. The other proposed estimator for integer CFOs employs a pseudonoise binary random sequence to assist in subCarrier arrangement and accurate estimation of the integer CFO. To demonstrate the efficiency of the proposed methods, numerical results are provided from computer simulation and analysis, and comparisons are made with other existing methods in the literature
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Carrier Frequency offset estimation for ofdm systems with null subCarriers
Vehicular Technology Conference, 2004Co-Authors: Jie Zhu, Wookwon LeeAbstract:In this paper, we propose an iterative CFO estimator using a specific pattern of alternating pilots and null subCarriers in training OFDM block. One major advantage of the proposed estimator is its simple structure. The proposed method estimates the CFO in an iterative fashion based on the signals at the null subCarriers and use of the estimated CFO to correct the Carrier Frequency for the next iteration. It is found that with the proposed scheme, the final estimation accuracy depends only on the signal to noise ratio and is insensitive to the initial Frequency offset. Simulation results demonstrate that the algorithm can achieve relatively high estimation accuracy within a few iterations in Frequency-selective fading channels.