The Experts below are selected from a list of 3090 Experts worldwide ranked by ideXlab platform

Limin Xiao - One of the best experts on this subject based on the ideXlab platform.

  • Codebook Design for uniform rectangular arrays of massive antennas
    IEEE Vehicular Technology Conference, 2013
    Co-Authors: Jingyu Li, Shichao Yu, Limin Xiao, Yufei Zhao, Jie Zeng, Xin Su, Xibin Xu
    Abstract:

    Massive Multiple-Input Multiple-Output (MIMO) is an emerging research field due to the increasing demand of spectral efficiency in wireless broadband systems, such as Long Term Evolution (LTE) which is proposed by 3GPP (Third Generation Partnership Project). Precoding is important to exploit the performance of massive MIMO, and Codebook Design is crucial due to the limited feedback channel. In this paper, we propose a novel double Codebook Design method based on a Kronecker-type approximation of the array correlation structure for the uniform rectangular array, which is preferable for the antenna deployment of massive MIMO systems. As a case study, we run simulations based on assumptions of the LTE-Advanced system which is extended to 32 dual-polarized antennas. The results verify that the proposed Codebook Design has remarkable performance gain compared to the traditional double Codebook under the uniform rectangular array setup.

  • VTC Spring - Codebook Design for Uniform Rectangular Arrays of Massive Antennas
    2013 IEEE 77th Vehicular Technology Conference (VTC Spring), 2013
    Co-Authors: Jie Zeng, Yufei Zhao, Limin Xiao
    Abstract:

    Massive Multiple-Input Multiple-Output (MIMO) is an emerging research field due to the increasing demand of spectral efficiency in wireless broadband systems, such as Long Term Evolution (LTE) which is proposed by 3GPP (Third Generation Partnership Project). Precoding is important to exploit the performance of massive MIMO, and Codebook Design is crucial due to the limited feedback channel. In this paper, we propose a novel double Codebook Design method based on a Kronecker-type approximation of the array correlation structure for the uniform rectangular array, which is preferable for the antenna deployment of massive MIMO systems. As a case study, we run simulations based on assumptions of the LTE-Advanced system which is extended to 32 dual-polarized antennas. The results verify that the proposed Codebook Design has remarkable performance gain compared to the traditional double Codebook under the uniform rectangular array setup.

Francisco Madeiro - One of the best experts on this subject based on the ideXlab platform.

  • Vector quantization Codebook Design based on Fish School Search algorithm
    Applied Soft Computing, 2018
    Co-Authors: Charles S. Fonseca, Felipe A. B. S. Ferreira, Francisco Madeiro
    Abstract:

    Abstract Vector Quantization (VQ) has been used in image coding systems since it allows high compression rates. Codebook Design can be seen as a high dimensional optimization problem and, in this scenario, swarm intelligence techniques have been used. This paper presents a new VQ Codebook Design algorithm based on swarm clustering. The method, based on Fish School Search (FSS) algorithm, is introduced. The FSS is embedded in Linde–Buzo–Gray (LBG) algorithm as a swarm clustering method, here called FSS-LBG. Also, a modification in the original FSS breeding operation is proposed in order to favor the exploration ability and, therefore, achieve better results in terms of PSNR of the reconstructed images. Simulation results show gains up to 1.57 dB in terms of PSNR when compared to LBG algorithm for the image Lena at 0.5625 bpp using a Codebook of size 512.

  • Accelerating Families of Fuzzy K-Means Algorithms for Vector Quantization Codebook Design
    Sensors (Basel Switzerland), 2016
    Co-Authors: Edson Mata, Silvio Bandeira, Paulo S. G. De Mattos Neto, Waslon Lopes, Francisco Madeiro
    Abstract:

    The performance of signal processing systems based on vector quantization depends on Codebook Design. In the image compression scenario, the quality of the reconstructed images depends on the Codebooks used. In this paper, alternatives are proposed for accelerating families of fuzzy K-means algorithms for Codebook Design. The acceleration is obtained by reducing the number of iterations of the algorithms and applying efficient nearest neighbor search techniques. Simulation results concerning image vector quantization have shown that the acceleration obtained so far does not decrease the quality of the reconstructed images. Codebook Design time savings up to about 40% are obtained by the accelerated versions with respect to the original versions of the algorithms.

  • Modified firefly algorithm applied to image vector quantisation Codebook Design
    International Journal of Innovative Computing and Applications, 2016
    Co-Authors: V. Severo, Herbert A. De Sá Leitão, Waslon Lopes, Juliano B. Lima, Francisco Madeiro
    Abstract:

    Vector quantisation VQ has been used in signal processing applications, such as steganography, watermarking and signal compression. The performance of signal processing systems based on VQ depends on the Designed Codebooks. In the present work, modifications are introduced in the firefly algorithm - Linde-Buzo-Gray FA-LBG for the purpose of VQ Codebook Design. The modified version differs from the original one mainly for attempting to assure a stronger influence of the training set in Codebook Design. In the scenario of image vector quantisation, simulation results show that the modified algorithm outperforms both the original one as well as the traditional LBG algorithm in terms of Codebook quality, assessed by the peak signal to noise ratio of the reconstructed images. Additionally, alternatives are presented to accelerate the proposed algorithm, which lead to execution time savings up to 90%.

  • PSO Algorithm Applied to Codebook Design for Channel-Optimized Vector Quantization
    IEEE Latin America Transactions, 2015
    Co-Authors: Herbert A. De Sá Leitão, Waslon T. A. Lopes, Francisco Madeiro
    Abstract:

    Vector quantization (VQ) has been used in signal compression systems. However, in the scenario of image transmission, VQ is very sensitive to channel errors. An approach to decrease such sensitivity is channel-optimized vector quantization (COVQ), which involves VQ Codebook Design taking into account the characteristics of the channel. In the present work, particle swarm optimization (PSO) is applied to Codebook Design for COVQ. Simulation results are presented for a variety of bit error rates of a binary symmetric channel (BSC) and reveal the effectiveness of the method in decreasing visual impairment by blocking artifacts in the reconstructed images, overperforming conventional COVQ Codebook Design in terms of peak signal to noise ratio of the reconstructed images for approximately 90% of exhaustive evaluations of image transmission over BSC.

  • SBRN - On Frequency Sensitive Competitive Learning for VQ Codebook Design
    2008 10th Brazilian Symposium on Neural Networks, 2008
    Co-Authors: P.h.e. Santo, Rebecca C. De Albuquerque, Daniel C. Cunha, Francisco Madeiro
    Abstract:

    Vector quantization (VQ) plays an important role in many image coding systems. The present paper examines the application of frequency sensitive competitive learning for VQ Codebook Design. Simulation results are presented for: the influence of the initialization on Codebook Design; the normalized entropy of the codevectors; the number of multiplications spent in the Codebook training; the "evolution" of the Codebook by the end of each iteration of the algorithm; the quality of the Designed Codebooks in terms of the peak signal to noise ratio of the reconstructed images. A comparison with both LBG (Linde-Buzo-Gray) and non frequency sensitive competitive learning is presented.

Xiang-gen Xia - One of the best experts on this subject based on the ideXlab platform.

  • Codebook Design for Millimeter-Wave Channel Estimation With Hybrid Precoding Structure
    IEEE Transactions on Wireless Communications, 2017
    Co-Authors: Zhenyu Xiao, Pengfei Xia, Xiang-gen Xia
    Abstract:

    In this paper, we study hierarchical Codebook Design for channel estimation in millimeter-wave (mmWave) communications with a hybrid precoding structure. Due to the limited saturation power of the mmWave power amplifier, we consider the per-antenna power constraint (PAPC). We first propose a metric, termed generalized detection probability (GDP), to evaluate the quality of an arbitrary codeword . This metric not only enables an optimization approach for mmWave Codebook Design, but also can be used to compare the performance of two different codewords/Codebooks. To the best of our knowledge, GDP is the first such metric, particularly for mmWave Codebook Design. We then propose a heuristic approach to Design a hierarchical Codebook exploiting beam widening with the multi-RF-chain sub-array (BMW-MS) technique. To obtain crucial parameters of BMW-MS, we provide two solutions, namely, a low-complexity search (LCS) solution to optimize the GDP metric and a closed-form (CF) solution to pursue a flat beam pattern. Performance comparisons show that BMW-MS/LCS and BMW-MS/CF achieve very close performances, and they outperform the existing alternatives under the PAPC.

  • hierarchical Codebook Design for beamforming training in millimeter wave communication
    IEEE Transactions on Wireless Communications, 2016
    Co-Authors: Zhenyu Xiao, Pengfei Xia, Tong He, Xiang-gen Xia
    Abstract:

    In millimeter-wave communication, large antenna arrays are required to achieve high power gain by steering toward each other with narrow beams, which poses the problem to efficiently search the best beam direction in the angle domain at both Tx and Rx sides. As the exhaustive search is time consuming, hierarchical search has been widely accepted to reduce the complexity, and its performance is highly dependent on the Codebook Design. In this paper, we propose two basic criteria for the hierarchical Codebook Design, and devise an efficient hierarchical Codebook by jointly exploiting sub-array and deactivation (turning-off) antenna processing techniques, where closed-form expressions are provided to generate the Codebook. Performance evaluations are conducted under different system and channel models. Results show superiority of the proposed Codebook over the existing alternatives.

T. Nakamura - One of the best experts on this subject based on the ideXlab platform.

  • High-speed Codebook Design by the multipath competitive learning on a systolic memory architecture
    2004
    Co-Authors: Kentaro Sano, C. Takagi, Kenichi Suzuki, T. Nakamura
    Abstract:

    So far, we have proposed a dedicated processor based on a systolic memory architecture to accelerate competitive learning (CL) for optimal Codebook Design. While this processor achieves high-speed Codebook Design, it has essential problems: limitation of hardware resources and lack in flexibility of Codebook size. To solve these problems, we present a multipath CL algorithm that allows the processor to flexibly handle the various size of a Codebook. The multipath CL on the FPGA-based prototype of the processor could Design Codebooks with comparable MSEs to the software simulation while the prototype processor achieved 2000 times faster processing speed than a general-purpose processor.

  • ITCC (1) - A systolic memory architecture for fast Codebook Design based on MMPDCL algorithm
    International Conference on Information Technology: Coding and Computing 2004. Proceedings. ITCC 2004., 2004
    Co-Authors: Kentaro Sano, C. Takagi, Ryusuke Egawa, K. Suzuki, T. Nakamura
    Abstract:

    Vector quantization with an adaptive Codebook is attractive for lossy data compression. During the last few decades, architectures have been proposed to accelerate adaptive Codebook Design that requires a huge amount of computation. However, they are mainly based on Kohonen competitive learning algorithm or LBG algorithms that have an essential problem, the under-utilization problem. This paper presents a systolic memory architecture for highspeed Codebook Design based on MMPDCL algorithm not suffering from the under-utilization problem. We modify MMPDCL algorithm to exploit parallelism and implement with simple hardware. Simulation results demonstrated that the modified MMPDCL algorithm can give Codebooks with comparable MSEs to the original MMPDCL algorithm.

  • Systolic computational memory approach to high-speed Codebook Design
    Proceedings of the Fifth IEEE International Symposium on Signal Processing and Information Technology 2005., 1
    Co-Authors: Kentaro Sano, C. Takagi, T. Nakamura
    Abstract:

    This paper presents a systolic computational memory approach to high-speed Codebook Design required for vector quantization (VQ). Our proposed systolic computational memory has the advantages of both the systolic array and computational RAM: massively parallel processing capability and wide bandwidth of internal memory. By introducing deferred update of a Codebook, the parallelism of the mini-max partial distortion competitive learning (MMPDCL) algorithm is enhanced and fully exploited by the proposed systolic computational memory for high-speed Codebook Design. The experiments of VQ-based image compression show that the FPGA-based prototype running at 33 MHz achieves about 400 times faster Codebook Design than a software approach on a general-purpose microprocessor running at 2 GHz

  • CLUSTER - Parallel competitive learning algorithm for fast Codebook Design on partitioned space
    2004 IEEE International Conference on Cluster Computing (IEEE Cat. No.04EX935), 1
    Co-Authors: Shintaro Momose, Kentaro Sano, K. Suzuki, T. Nakamura
    Abstract:

    Vector quantization (VQ) is an attractive technique for lossy data compression, which is a key technology for data storage and/or transfer. So far, various competitive learning (CL) algorithms have been proposed to Design optimal Codebooks presenting quantization with minimized errors. However, their practical use has been limited for large scale problems, due to the computational complexity of competitive learning. This work presents a parallel competitive learning algorithm for fast code-book Design based on space partitioning. The algorithm partitions input-vector space into some subspaces, and independently Designs corresponding subCodebooks for these subspaces with computational complexity reduced. Independent processing on different subspaces can be processed in parallel without synchronization overhead, resulting in high scalability. We perform experiments of parallel Codebook Design on a commodity PC cluster with 8 nodes. Experimental results show that the high speedup of the Codebook Design is obtained without increase of quantization errors.

Zhenyu Xiao - One of the best experts on this subject based on the ideXlab platform.

  • Codebook Design for Millimeter-Wave Channel Estimation With Hybrid Precoding Structure
    IEEE Transactions on Wireless Communications, 2017
    Co-Authors: Zhenyu Xiao, Pengfei Xia, Xiang-gen Xia
    Abstract:

    In this paper, we study hierarchical Codebook Design for channel estimation in millimeter-wave (mmWave) communications with a hybrid precoding structure. Due to the limited saturation power of the mmWave power amplifier, we consider the per-antenna power constraint (PAPC). We first propose a metric, termed generalized detection probability (GDP), to evaluate the quality of an arbitrary codeword . This metric not only enables an optimization approach for mmWave Codebook Design, but also can be used to compare the performance of two different codewords/Codebooks. To the best of our knowledge, GDP is the first such metric, particularly for mmWave Codebook Design. We then propose a heuristic approach to Design a hierarchical Codebook exploiting beam widening with the multi-RF-chain sub-array (BMW-MS) technique. To obtain crucial parameters of BMW-MS, we provide two solutions, namely, a low-complexity search (LCS) solution to optimize the GDP metric and a closed-form (CF) solution to pursue a flat beam pattern. Performance comparisons show that BMW-MS/LCS and BMW-MS/CF achieve very close performances, and they outperform the existing alternatives under the PAPC.

  • hierarchical Codebook Design for beamforming training in millimeter wave communication
    IEEE Transactions on Wireless Communications, 2016
    Co-Authors: Zhenyu Xiao, Pengfei Xia, Tong He, Xiang-gen Xia
    Abstract:

    In millimeter-wave communication, large antenna arrays are required to achieve high power gain by steering toward each other with narrow beams, which poses the problem to efficiently search the best beam direction in the angle domain at both Tx and Rx sides. As the exhaustive search is time consuming, hierarchical search has been widely accepted to reduce the complexity, and its performance is highly dependent on the Codebook Design. In this paper, we propose two basic criteria for the hierarchical Codebook Design, and devise an efficient hierarchical Codebook by jointly exploiting sub-array and deactivation (turning-off) antenna processing techniques, where closed-form expressions are provided to generate the Codebook. Performance evaluations are conducted under different system and channel models. Results show superiority of the proposed Codebook over the existing alternatives.

  • circular antenna array based Codebook Design and training method for 60ghz beamforming
    Wireless Communications and Networking Conference, 2013
    Co-Authors: Wei Feng, Zhenyu Xiao, Depeng Jin, Lieguang Zeng
    Abstract:

    Beamforming is necessary in 60GHz millimeterwave communications in order to compensate for high path loss. A complete beamforming algorithm includes Codebook Design and beam training. The existing beamforming protocol of IEEE 802.15.3c standard has following flaws: (1) Not all three beamforming pattern types (quasi-omni pattern, sector and beam) have their own Codebooks; (2) Almost every beam points to two directions, one of which is expected but the other one is unwanted; (3) Setup time of beam training is long. This paper proposes a Codebook Design and corresponding training procedure based on circular antenna array with a two-layer-structure. It allows every pattern type to own its corresponding Codebook and highly directional antenna radiation pattern. The training setup time is reduced to around half of 3c training time. Performance evaluations also manifest that the proposed algorithm leads to less antenna gain loss and more robust performance than the 3c standard.