A novel adaptive antenna architecture - subcarrier clustering for high-speed OFDM systems in presence of rich co-channel interference

Sun, Yong; Matsuoka, Hiroaki

doi:10.1109/vtc.2002.1002880

Cited by 14 publications

(21 citation statements)

References 5 publications

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“…The structure of the receiver is the extension of a single antenna OFDM receiver and is similar to the receiver of a SIMO-OFDM system with post-FFT scheme [7][8][9]. Receive beamforming is implemented for the kth subcarrier by multiplication of the received OFDM symbols R m r (k), m r = 1, .…”

Section: Post-fft Mimo-ofdm Structurementioning

confidence: 99%

“…Due to the presence of the DFT operation in the OFDM demodulation chain two main schemes were proposed; beamforming in time-domain (pre-FFT scheme) and beamforming in frequency domain (post-FFT scheme) [3][4][5][6][7][8][9][10]. While beamforming weights in the pre-FFT scheme are directly applied to time domain signals in the receiver [3,5,6], in the post-FFT scheme time domain signals are first converted to frequency domain, by applying DFT to each received signal, and then performing beamforming on each individual subcarrier [4,[7][8][9][10]. Since the post-FFT scheme uses DFT in each antenna it is computationally more complex than the pre-FFT scheme.…”

Section: Introductionmentioning

confidence: 99%

“…These methods often use criteria such as maximization of SNR, mutual information, or minimization of BER to obtain the beamforming weights [4][5][6][7]13]. In reference based methods, however, the weights are obtained by minimizing the error between the received signal and a reference signal such as pilot symbols or preamble blocks [3,8,12]. Blind methods are obviously more complex and less effective in performance than reference-based methods which nevertheless encounter less spectral efficiency [14].…”

Section: Introductionmentioning

confidence: 99%

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Post-FFT Beamforming in a Pilot-Assisted MIMO-OFDM System

Asadollahi-Yazdi

Seydnejad

2014

Wireless Pers Commun

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It has been shown that by employing beamforming in the receiver of a Single-Input Multiple-Output-orthogonal frequency division multiplexing (SIMO-OFDM) system its performance has been greatly improved by suppressing co-channel interferences and mitigating fading effects of the channel. To get even greater performance applying a similar beamforming technique to the transmitter side of a Multiple-Input Multiple-Output (MIMO)-OFDM system was further employed. However, while in SIMO-OFDM systems both blind and reference-based methods have been investigated, in MIMO-OFDM systems only algorithms based on blind methods have been proposed so far. In this article we develop a reference-based joint transmit-receive beamforming technique, based on pilot symbols, in a MIMO-OFDM system. Post-FFT scheme is used in both sides as the beamforming method. Appropriate adaptive algorithms are developed to obtain the joint optimal beamforming weights in the receiver by minimizing the error signal between the estimated pilot symbols and their actual values. Receiver weights are used locally whereas transmitter weights are sent to the transmitter through a low-rate feedback channel similar to blind methods. The effect of various factors on the performance of the proposed beamforming structure is considered and it is shown that the joint transmit-receive beamforming is more effective than the sole receive beamforming although the improvement due to transmit beamforming is limited by the total transmit power constraint.

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Section: Post-fft Mimo-ofdm Structurementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Post-FFT Beamforming in a Pilot-Assisted MIMO-OFDM System

Asadollahi-Yazdi

Seydnejad

2014

Wireless Pers Commun

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“…For instance, if a N sub-carrier OFDM system with S antenna elements undergoes a total of L BF recursions, then Pre-FFT has complexity of the order of S × L where as the Post-FFT has N × S × L. Moreover, Post-FFT has scalability issues with regards to number of sub-carriers, with complexity of the BF mechanism being direct proportional to number of OFDM sub-carriers. To reduce complexity of the Post-FFT approach, several solutions have been proposed such as sub-carrier clustering based BF [19] and Multi-Stage BF [20].…”

Section: Related Work and Algorithm Formulationmentioning

confidence: 99%

“…vector that is computed using pilot sub-carriers only. Furthermore, µ must satisfy (19) and (20) just as was the case in ITBF. …”

Section: Conventional Lms Beamformingmentioning

confidence: 99%

Iterative turbo beamforming for orthogonal frequency division multiplexing-based hybrid terrestrial-satellite mobile system

2012

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exhibits a high degree of sensitivity to the pilot sub-carriers. Increasing the number of reference pilots significantly improves BF performance as well as system performance. However, this increase comes at the cost of data throughput which inevitably shrinks due to transmission of additional pilots. Hence an approach where reference signals available to the BF process can be increased without transmitting additional pilots can exhibit superior system performance without compromising throughput.Thus, in this paper we present a novel three-stage Iterative Turbo Beamforming (ITBF) algorithm for an OFDM based Hybrid Terrestrial-Satellite Mobile System which utilises both pilots and data to perform interference mitigation. Data sub-carriers are utilised as virtual reference signals in the BF process. Results show that when compared to non-iterative conventional BF, the proposed ITBF exhibits Bit Error Rate Gain (BERG) of up to 2.5 dB with only one iteration.

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