A novel frequency offset estimation technique for Mobile WiMAX

Carrier frequency offset (CFO) is a factor that corrupts subchannel orthogonality resulting to performance degradation in multiple‐input multiple‐output orthogonal frequency division multiplexing systems. We investigate the effect of CFO on the channel estimation and the effect of both CFO and channel estimation on the system capacity. The main result of the paper is a lower bound on the capacity for a given CFO and channel estimation error covariance. The lower bound is based on the Gaussian bound of the multiplicative noise because of channel estimation errors. Copyright © 2012 John Wiley & Sons, Ltd.

Section: Numerical Resultsmentioning

confidence: 99%

Section: Pilot-assisted Channel Estimationmentioning

confidence: 88%

Impact of carrier frequency offset on the capacity of MIMO‐OFDM systems

Tutgun

Aktas

2012

“…Then, the equivalent received baseband signal is

\overset{r}{true} (t) MathClass-rel= {MathClass-op\sum}_{i MathClass-rel= 1}^{S} ξ_{i} s ((), \frac{1 MathClass-bin+ α}{1 MathClass-bin+ \overset{α}{true}} t MathClass-bin- τ_{i}) e^{j 2 π f_{normalc} ((), \frac{α MathClass-bin- \overset{α}{true}}{1 MathClass-bin+ \overset{α}{true}} t MathClass-bin- τ_{i})} MathClass-bin+ η_{normalB} (t)

where η B ( t ) is the equivalent baseband noise. Although we intend to make (1 + α ) as close to

(1 MathClass-bin+ \overset{α}{true})

as possible, there is a residual carrier frequency offset defined as

f_{normalo} MathClass-rel= ((), \frac{α MathClass-bin- \overset{α}{true}}{1 MathClass-bin+ \overset{α}{true}}) f_{normalc}

which can be viewed as uniform for the whole band. Hence, a wideband system is converted into a narrowband system with frequency‐independent carrier frequency offset, which can be conveniently compensated in the wavelet filter bank systems .…”

Section: Problem Formulationmentioning

confidence: 99%

“…Although we intend to make .1C˛/ as close to .1C Ǫ/ as possible, there is a residual carrier frequency offset [24] defined as…”

Section: Problem Formulationmentioning

confidence: 99%

Sparse channel estimation for wavelet‐based underwater acoustic communications

2012

In this paper, concerning underwater acoustic (UWA) communications, we propose a wavelet filter bank system as the extension of orthogonal frequency‐division multiplexing system. We exploit the convolutional structure of a UWA channel and formulate the pilot‐assisted channel estimation as a sparse recovery problem. Then, we investigate the restricted isometry property of the measurement matrix via eigenvalue analysis and Gershgorin circle theorem. The sparse recovery problem is proven to satisfy the restricted isometry property. Moreover, we also propose a low‐complexity complex‐field homotopy algorithm for sparse channel estimation, regarding the fact that the channel taps of each path are usually complex valued in practice. Simulation results show that the wavelet filter bank system achieves more accurate UWA channel estimation performance than orthogonal frequency‐division multiplexing system under the same conditions of bandwidth, duration, data rate and channel profile. The proposed complex homotopy algorithm outperforms orthogonal matching pursuit (OMP) and stagewise OMP in both systems, whereas its computational complexity is similar to OMP. Copyright © 2012 John Wiley & Sons, Ltd.

“…In particular, timing and frequency errors can lead to a performance degradation [4,5]. For these reasons, accurate synchronisation is a major issue of an OFDM receiver, and the estimation of timing and frequency offsets has been extensively studied in the literature [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Computationally effective sampling frequency‐offset estimation for OFDM‐based LTE downlink systems

You

Shin

Song

et al. 2014

In this paper, we present a low‐complexity sampling frequency‐offset (SFO) estimation scheme suitable for the 3GPP long‐term evolution (LTE) downlink system. First, a novel SFO estimation method for a pilot‐aided orthogonal frequency division multiplexing system is proposed providing a good performance with reduced complexity. To achieve low complexity, the proposed estimation scheme uses a central conjugate‐symmetric primary synchronisation signal specified in the LTE standard, which eases the SFO estimation at the receiver. For performance evaluation, we derive the mean square error expression of the proposed frequency estimation scheme. Simulations show that the proposed frequency estimation scheme can detect the SFO with higher accuracy and much lower complexity, compared with the conventional estimation schemes. Copyright © 2014 John Wiley & Sons, Ltd.