Symbol-wise beamforming for MIMO-OFDM transceivers in the presence of co-channel interference and spatial correlation

Pollok, Andre; Cowley, William G.; Letzepis, Nick

doi:10.1109/twc.2009.12.081678

Cited by 16 publications

(26 citation statements)

References 18 publications

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“…Similar to blind methods, we assume in our simulations that the feedback channel has zero delay with no error [16][17][18][19][20][21]. The effect of the delay in the feedback channel has been considered by some authors [25,26].…”

Section: Choose Initial Values For the Transmitter Weightsmentioning

confidence: 99%

“…Since using beamforming in the receiver of a SIMO-OFDM system has greatly improved the system performance, its idea was also extended to the transmitter side, resulting in a Multiple-Input Multiple-Output (MIMO) OFDM beamforming configuration [1,[15][16][17][18][19][20][21]. Similar to a SIMO-OFDM system, both pre-FFT and post-FFT schemes have been employed to implement the beamforming in a MIMO-OFDM system.…”

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: Choose Initial Values For the Transmitter Weightsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Asadollahi-Yazdi

Seydnejad

2014

Wireless Pers Commun

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“…The authors extended their work for SIMO-OFDM wireless ad-hoc systems in [14] and showed effective CCI mitigation using a similar SMI based iterative beamformer. Authors in [15] propose an iterative symbol-level transmit and receive beamformer with the objective of SINR maximisation, whereas authors in [16] propose a smooth beamformer based on orthogonal iterations across sub-carriers. Specific to OFDM, recently Zhao et al [17] proposed a turbo based channel estimator which aims to reduce ICI induced in OFDM systems due to users mobility.…”

Section: Related Work and Algorithm Formulationmentioning

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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“…BF has been studied in detail with reference to OFDM [3]- [5]. For the hybrid system, we have previously proposed several adaptive BF strategies [6]- [8].…”

Section: Introductionmentioning

confidence: 99%

Semi-Adaptive Beamforming for OFDM Based Hybrid Terrestrial-Satellite Mobile System

Khan

Imran

Evans

2012

IEEE Trans. Wireless Commun.

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Adaptive interference mitigation requires significant resources due to recursive processing. Specific to satellite systems, interference mitigation by employing adaptive beamforming at the gateway or at the satellite both have associated problems. While ground based beamforming reduces the satellite payload complexity, it results in added feeder link bandwidth requirements, higher gateway complexity and suffers from feeder link channel degradations. On the other hand, employing adaptive beamforming onboard the satellite gives more flexibility in case of variation in traffic dynamics and also for changing of beam patterns. However, these advantages come at the cost of additional complexity at the satellite.In pursuit of retaining the benefits of onboard beamforming and to reduce the complexity associated with adaptive processing, we here propose a novel semi-adaptive beamformer for a Hybrid TerrestrialSatellite Mobile System. The proposed algorithm is a dual form of beamforming that enables adaptive and non-adaptive processing to coexist via a robust gradient based switching mechanism. We present a detailed complexity analysis of the proposed algorithm and derive bounds associated with its power requirements. In the scenarios studied, results show that the proposed algorithm consumes up to 98% less filter computing power as compared to full-adaptive case without compromising on system performance.

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Symbol-wise beamforming for MIMO-OFDM transceivers in the presence of co-channel interference and spatial correlation

Cited by 16 publications

References 18 publications

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

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

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

Semi-Adaptive Beamforming for OFDM Based Hybrid Terrestrial-Satellite Mobile System

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