• Title/Summary/Keyword: Adaptive beamforming

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An LMS-Based Beamforming Algorithm for Antenna Array Applied to an MC-CDMA System

  • Tuan, Le-Minh;Su, Pham-Van;Kim, Jewoo;Giwan Yoon
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2002.05a
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    • pp.249-254
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    • 2002
  • In this paper, we propose an adaptive Beamforming Algorithm, called MC-LMS, for adaptive antenna applied to an MC-CDMA system. New method for updating the weight vector based on the MSE criterion is derived. Computer simulations show that MC-LMS algorithm is capable of rejecting co-channel interference that affects the MC-CDMA system. Thus, the BER performance of the MC-CDMA system is much higher than that of the MC-CDMA system without using adaptive antenna and that of the DS-CDMA system with adaptive antenna in multi-path Rayleigh fading channel.

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A Modified MMSE Algorithm for Adaptive Antennas in OFDM/CDMA Systems

  • Su, Pham-Van;Tuan, Le-Minh;Kim, Jewoo;Giwan Yoon
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2002.05a
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    • pp.509-513
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    • 2002
  • This paper presents a semi-blind Minimum Mean Square Error (MMSE) beamforming adaptive algorithm used far OFDM/CDMA combined system. The proposed algorithm exploits the transmitting pilot signal in the initial period of the transmission to update the weight vector. Then it applies the blind adaptive period to update the weight vector, in which the pilot signal is no longer used. The derivation of the algorithm based on the Mean Square Error (MSE) criterion is also presented. Computer simulation is carried out to verify the performance of the proposed approach.

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Adaptive beamforming for a PF-OFDM system using LMS algorithm (LMS기반 PF-OFDM에서의 적응 빔포밍 설계)

  • Yoo, Kyung-Rul;Oh, Jun-Suk
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.55 no.3
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    • pp.119-123
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    • 2006
  • The orthogonal frequency-division multiplexing (OFDM) technique is well known to be robust against the frequency-selective fading in wireless channels. It is due to the exploitation of a guard interval that is inserted at beginning of each OFDM symbol. Based on the conventional OFDM and a polyphase filtered orthogonal frequency division multiplexing (PF-OFDM) technique, we developed an adaptive beamforming algorithm for antenna arrays. The proposed algorithm would lead to an efficient use of channel, since it is possible to eliminate a guard interval and also easily suppress interchannel interference at the same time. In this paper, a series of computer simulations have been provided to show the performance of the proposed system.

Enhanced Adaptive Beamforming and Null Steering Algorithms in Cognitive Radio System

  • Zhuang, Zhili;Sohn, Sung-Hwan;Kim, Jae-Moung
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.34 no.11A
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    • pp.822-830
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    • 2009
  • The spectrum efficiency of mobile communication networks can be improved dramatically adopting multiple antennas technologies. In order to guarantee the licensed rights of primary user (PU), the cognitive radio system should perform in a relatively low interference manner when it gets access to the spectrum of licensed networks. In this paper, we explore a uniformly distributed circular antenna array to implement beamforming algorithm that is accomplished by optimization method at the base station of cognitive radio networks, and therefore we can suppress the interference to PU by steering quite low transmission power toward PU and constructing a narrow beam toward cognitive user (CU). By reducing the constraint number of the optimization problem, we also propose a null steering algorithm that steers rather low radiation power toward PU, while the other areas in the same cell are covered by radiation power except the local area around PU. It is pursued to reduce the computation load and enlarge the capacity of cognitive radio networks extremely. The simulation results demonstrate that the proposed algorithms process superior performance.

Fast Millimeter-Wave Beam Training with Receive Beamforming

  • Kim, Joongheon;Molisch, Andreas F.
    • Journal of Communications and Networks
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    • v.16 no.5
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    • pp.512-522
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    • 2014
  • This paper proposes fast millimeter-wave (mm-wave) beam training protocols with receive beamforming. Both IEEE standards and the academic literature have generally considered beam training protocols involving exhaustive search over all possible beam directions for both the beamforming initiator and responder. However, this operation requires a long time (and thus overhead) when the beamwidth is quite narrow such as for mm-wave beams ($1^{\circ}$ in the worst case). To alleviate this problem, we propose two types of adaptive beam training protocols for fixed and adaptive modulation, respectively, which take into account the unique propagation characteristics of millimeter waves. For fixed modulation, the proposed protocol allows for interactive beam training, stopping the search when a local maximum of the power angular spectrum is found that is sufficient to support the chosen modulation/coding scheme. We furthermore suggest approaches to prioritize certain directions determined from the propagation geometry, long-term statistics, etc. For adaptive modulation, the proposed protocol uses iterative multi-level beam training concepts for fast link configuration that provide an exhaustive search with significantly lower complexity. Our simulation results verify that the proposed protocol performs better than traditional exhaustive search in terms of the link configuration speed for mobile wireless service applications.

Duvall-Structure-Based Adaptive Beamforming Method for Cancellation of Coherent and Incoherent Interferences (코히런트/인코히런트 간섭신호제거를 위한 Duvall 구조에 기초한 적응 빔형성 방법)

  • Cho, Yang-Ho
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.33 no.10A
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    • pp.1006-1012
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    • 2008
  • This paper presents a Duvall-structure-based adaptive beamforming method which efficiently cancels coherent and incoherent interferences. The proposed method exploits several correlation vectors to increase the dimension of the weight vector, compared to the existing method which uses a single correlation vector only. The increased dimension of the weight vector leads to an improvement in the signal-to-interference plus noise ratio (SINR) performance. Moreover, the proposed method can suppress more interferences than the existing one. Simulation shows that the former is superior to the latter in terms of the steady-state and transient responses.

Adaptive Chirp Beamforming for Direction-of-Arrival Estimation of Wideband Chirp Signals in Sensor Arrays (광대역 chirp 신호의 방위각 추정을 위한 적응 빔 형성)

  • Kim, Jeong-Soo;Choi, Byung-Woong;Bae, Eun-Hyon;Lee, Kyun-Kyung
    • The Journal of the Acoustical Society of Korea
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    • v.27 no.2
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    • pp.87-91
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    • 2008
  • In this paper, the adaptive chirp beamforming method is proposed to solve the bias problem in the direction-of-arrivals (DOAs) estimation of the wideband chirp signals which have an identical time-frequency parameter and are emanated from different directions. The source location bias results from the interferences impinging on the array from the other directions. The proposed method exploits the time-frequency structure of the chirp signal based on STMV (STeered Minimum Valiance) to improve the DOA estimation performance by minimizing the chirp interferences effectively. Simulation results show the DOA estimation performance achieved by the proposed method as compared to the conventional methods.

A Study on Adaptive Sparse Matrix Beamforming Algorithm of Error Beam Steering Vector for Target Estimation (목표물 추정을 위한 오차 빔 지향벡터의 적응 회소 행렬 빔형성 알고리즘 연구)

  • Kang, Kyoung Sik
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.7 no.2
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    • pp.111-116
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    • 2014
  • In this paper, we estimates the direction of arrival of desired a target using linear array antenna in wireless communication. Direction of arrival estimation is to estimate for desired target position among incident signals on receiver array antennas. This paper improved estimation of direction of arrival for target using optimum weight, high resolution adaptive beamforming algorithm, and sparse matrix for driection of arrival estimation. Through simulation, we showed that we are performance the analysis to compare general algorithm with proposed algorithm. We show that propose algorithm more improve for direction of estimation than general beamforming algorithm.

Beamforming Optimization Using Filterbank-based Frost Algorithm (필터뱅크 기반 프로스트 알고리즘을 이용한 빔포밍 최적화)

  • Park, Ji-Hoon;Lee, Sung-Joo;Hong, Jeong-Pyo;Jeong, Sang-Bae;Hahn, Min-Soo
    • MALSORI
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    • no.66
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    • pp.73-86
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    • 2008
  • Beamforming is one of the spatial filtering techniques which extract only desired signals from noisy environments using microphone arrays. Fixed beamforming is a simple concept and easy to implement. However, it does not show good performance in real noisy conditions. As an adaptive beamforming, Frost algorithm can be a good candidate. It uses the concept of the linearly constrained minimum variance (LCMV) algorithm. The difference between the Frost and the LCMV algorithm is the error correction scheme which is very effective feature in the aspect of performance. In this paper, as quadrature mirror filtering (QMF)-based filterbank is utilized as the pre-processing of the Frost beamformning, the filter length and the learning rate of each band is optimized to improve the performance. The performance is measured by the signal-to-noise ratio (SNR) and the Bark's scale spectral distortion (BSD).

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A New Adaptive Beamforming Algorithm toy Smart Antennas Applied to an OFDM System

  • Tuan, Le-Minh;Su, Pham-Van;Kim, Jewoo;Giwan Yoon
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2002.05a
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    • pp.238-242
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    • 2002
  • In this paper. we consider an OFDM system with cochannel interference and the use of adaptive antenna arrays to suppress such interference. Based on the conventional RLS criterion, we derive a new Recursive Least Square (RLS) adaptive beamforming algorithm for antenna arrays applied in an OFDM system. Computer simulation shows that. when applied to the OFDM system. the proposed algorithm is capable of combating cochannel interference in both AWGN channel and multipath Rayleigh fading channel with AWGN.

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