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carrier-frequency-offsets
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Integer frequency offset recovery in OFDM systems
, Article 18th Asia-Pacific Conference on Communications: "Green and Smart Communications for IT Innovation", APCC 2012, Jeju Island, 15 October 2012 through 17 October 2012 ; 2012 , Pages 641-646 ; Shayesteh, M. G ; Sharif University of Technology
2012
Abstract
This paper addresses the estimation of the integer part of the carrier frequency offset (CFO) in orthogonal frequency division multiplexing (OFDM) systems. A novel method is presented based on the maximum likelihood (ML) approach that jointly estimates the channel impulse response (CIR) and the integer CFO. The new scheme estimates the CIR by using pilots and obtains the estimate of the integer CFO by taking advantage of the effect of the CFO on the CIR and data symbols. The performance of the new method is evaluated in Rayleigh fading channels. The results demonstrate that the proposed scheme significantly outperforms the previous methods
Novel coarse timing synchronization methods in OFDM systems using fourth-order statistics
, Article IEEE Transactions on Vehicular Technology ; Volume 64, Issue 5 , 2015 , Pages 1904-1917 ; 00189545 (ISSN) ; Abdzadeh Ziabari, H ; Shayesteh, M. G ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
In this paper, the problem of coarse timing synchronization in orthogonal frequency-division multiplexing (OFDM) systems is investigated, and two new timing metrics with better performance are presented. The new metrics take advantage of two novel differential normalization functions that are based on the fourth-order statistics and are designed depending on the value of carrier frequency offset (CFO). The proposed timing metrics are theoretically evaluated using two different class separability criteria. It is shown that the new schemes considerably increase the difference between the correct and wrong timing points in comparison with previous methods. The computational complexity of the...
SINR analysis of time and frequency offsets in OFDM systems
, Article Proceedings - Conference on Local Computer Networks, LCN, 4 October 2011 through 7 October 2011 ; October , 2011 , Pages 855-859 ; 9781612849287 (ISBN) ; Khalaj, B. H ; Sharif University of Technology
2011
Abstract
In this paper, the impact of both time offsets (TOs) and carrier frequency offsets (CFOs) on the average output signal-to-interference-plus-noise ratio (SINR) in a frequency selective channel is investigated with a novel approach. First, TOs are partitioned into five cases based on how they occur. Then the mathematical models for different cases are derived. Considering CFOs and benefiting from the obtained models, closed-form expression for the SINR in each case is derived. It is proved that, SINR is independent of the observed subcarrier for the given TO and CFO. Besides, it is shown that the performance of the affected system deteriorates rapidly as the number of subcarriers increases. It...
Design and Implementation of Time and Frequency Synchronization in LTE
, Article IEEE Transactions on Very Large Scale Integration (VLSI) Systems ; Volume 23, Issue 12 , January , 2015 , Pages 2970-2982 ; 10638210 (ISSN) ; Shabany, M ; Nezamalhosseini, A ; Gulak, G ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
A novel architecture for efficient time and frequency synchronization, applied to the long-term evolution (LTE) standard, is proposed. For symbol timing, we propose applying a symbol-folding method on top of the sign-bit reduction technique, leading to a novel algorithm for the cyclic prefix-type recognition in LTE. Following the symbol timing, the fractional carrier frequency offset is estimated and compensated using an adaptive gain loop, which allows for a high-accuracy compensation in a short interval. In the frequency domain, for cell search, we propose a sign-bit reduction technique on top of the matched filter method for the primary synchronization signal detection. In addition, we...