Carrier Frequency Offset Estimation for OFDM Systems with Null Subcarriers

Zhu, Jinlin; Lee, Wookwon

doi:10.1109/tvt.2006.878608

Cited by 39 publications

(24 citation statements)

References 19 publications

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“…Equation 4 can be split up into the wanted user modulation symbol X ς,v of user ς who exclusively transmits on subcarrier v and ICI noise N I C I v on v from the remaining subcarriers k ∈ {[0, N − 1]\v}, see (5).…”

Section: System Modelmentioning

confidence: 99%

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Effect of Carrier Frequency Offset on the Channel Capacity in Multiuser OFDM-FDMA Systems

Stemick

Rohling

2007

Wireless Pers Commun

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Orthogonal Frequency Division Multiplexing (OFDM) is a very robust transmission procedure in multipath and frequency selective radio channels. A Frequency Division Multiple Access (FDMA) resource allocation technique offers the opportunity of a detailed link adaptation scheme. The combination of these transmission-and multiple access techniques in OFDM-FDMA is an ideal and very strong candidate for the downlink of future fourth generation (4G) mobile communication systems. This technical combination offers high cell capacities by exploiting the inherent multiuser diversity effect of the system. To apply OFDM-FDMA in the uplink, the time and carrier synchronization accuracy becomes very important. Non-ideal synchronization of the user signals to the carrier frequency of the base station leads to intercarrier interferences (ICI). In this paper, an analytical model for the ICI consideration in the uplink of a multiuser OFDM-FDMA based system is derived. The impact of the carrier frequency offset (CFO) on the performance of a cellular multiuser system with respect to different subcarrier allocation schemes is analyzed.

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Section: System Modelmentioning

confidence: 99%

“…The actual measurement of the CFO can be done with dedicated signals or blindly, cf. [5][6][7] and references therein. However, such a procedure needs a large measurement overhead and its performance will strongly depend on measurement accuracies.…”

Section: Introductionmentioning

confidence: 99%

Effect of Carrier Frequency Offset on the Channel Capacity in Multiuser OFDM-FDMA Systems

Stemick

Rohling

2007

Wireless Pers Commun

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“…Remark 3 Most of the null subcarrier based frequency offset estimation methods proposed in the literature use a null subcarrier structure which is a direct frequency domain equivalent of the training symbol patterns utilized in time domain methods [7,8,29]. Hence the bandwidth efficiencies of these methods are not different from the training preamble based methods.…”

Section: Remarkmentioning

confidence: 99%

“…Recently a null subcarrier based method is proposed which is capable of estimating the fractional and integer frequency offsets but the training overhead is very high [8]. A similar technique is proposed in [29], but it needs an overhead of two OFDM symbols which is bandwidth expensive.…”

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confidence: 99%

An Efficient Maximum Likelihood Carrier Frequency Offset Estimator for OFDM Using Null Subcarriers and Cyclic Prefix

Sameer

Kumar

2009

Wireless Pers Commun

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Accurate estimation of carrier frequency offset (CFO) is an important requirement in orthogonal frequency-division multiplexing (OFDM) based wireless communication systems. In this paper, we propose a hybrid procedure to accomplish this task efficiently. One of the key importance of the approach is the judicious combination of two independent estimators so as to reduce the bandwidth overhead and computational complexity over many conventional methods. It employs the cyclic prefix and a few null subcarriers, respectively, for the fractional and integer frequency offset estimations. We also propose a novel null subcarrier allocation scheme based on Fibonacci series. The range of frequency offset that can be estimated by the proposed technique is equal to the full OFDM bandwidth. Furthermore, performance of the proposed CFO estimator is mathematically analyzed by deriving an expression for the bit error probability of the receiver under Rayleigh fading channel and the Cramer-Rao lower bound for the mean square estimation error. For moderate SNRs, our approach is shown to greatly outperform some recently published methods in terms of BER performance, bandwidth overhead and receiver complexity.

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“…To compensate the carrier frequency offset, several synchronization algorithms have been proposed in the literature [3,6,14,15,19,22,24]. The frequency offset estimation algorithms for MB-OFDM system are reported in [7, 9-11, 16, 20, 21, 23].…”

Section: Introductionmentioning

confidence: 99%

A Technique for Frequency Synchronization in Multi-Band OFDM in Realistic UWB Channel

Chakrabarti

Kumar

2009

Circuits Syst Signal Process

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This paper presents a highly accurate frequency offset estimation algorithm for multi-band orthogonal frequency division multiplexing (MB-OFDM) systems effective for realistic ultra-wideband (UWB) environment. The proposed algorithm derives its estimates based on phase differences in the received subcarrier signals of several successive OFDM symbols in the preamble. We consider different carrier frequency offsets and different channel responses in different bands to keep the analysis and simulation compatible for practical multi-band UWB scenario. Performance of the proposed algorithm is studied by means of bit error rate (BER) performance of MB-OFDM system. In order to compare the variance of the synchronizer to that of the theoretical optimum, we derive the Cramer-Rao lower bound (CRLB) of the estimation error variance and compare it with the simulated error variance both in additive white Gaussian noise and UWB channel model (CM) environments, CM1-CM4. Next, we modify the estimation algorithm by proposing a multi-band averaging frequency offset synchronization (MBAFS) scheme. We establish superior BER performance with MBAFS compared to our first scheme. We calculate modified CRLB for MBAFS and compare it with simulation results for CM1-CM4. Both analysis and simulation show that MBAFS algorithm can estimate the carrier frequency offset effectively and precisely in UWB fading channels for MB-OFDM applications. We also analyze the computational complexity of both the proposed algorithms in order to verify their feasibility of implementation in practical UWB receiver design.

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Carrier Frequency Offset Estimation for OFDM Systems with Null Subcarriers

Cited by 39 publications

References 19 publications

Effect of Carrier Frequency Offset on the Channel Capacity in Multiuser OFDM-FDMA Systems

Effect of Carrier Frequency Offset on the Channel Capacity in Multiuser OFDM-FDMA Systems

An Efficient Maximum Likelihood Carrier Frequency Offset Estimator for OFDM Using Null Subcarriers and Cyclic Prefix

A Technique for Frequency Synchronization in Multi-Band OFDM in Realistic UWB Channel

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