Presents a theoretically very simple, yet efficient, multiresolution approach to gray-scale and rotation invariant texture classification based on local binary patterns and nonparametric discrimination of sample and prototype distributions. The method is based on recognizing that certain local binary patterns, termed "uniform," are fundamental properties of local image texture and their occurrence histogram is proven to be a very powerful texture feature. We derive a generalized gray-scale and rotation invariant operator presentation that allows for detecting the "uniform" patterns for any quantization of the angular space and for any spatial resolution and presents a method for combining multiple operators for multiresolution analysis. The proposed approach is very robust in terms of gray-scale variations since the operator is, by definition, invariant against any monotonic transformation of the gray scale. Another advantage is computational simplicity as the operator can be realized with a few operations in a small neighborhood and a lookup table. Experimental results demonstrate that good discrimination can be achieved with the occurrence statistics of simple rotation invariant local binary patterns.

/pdf/multiresolution-gray-scale-and-rotation-invariant-texture-1b1y2fta4g.pdf

Multiresolution gray-scale and rotation invariant texture classification with local binary patterns

Presents a review of 200 references in content-based image retrieval. The paper starts with discussing the working conditions of content-based retrieval: patterns of use, types of pictures, the role of semantics, and the sensory gap. Subsequent sections discuss computational steps for image retrieval systems. Step one of the review is image processing for retrieval sorted by color, texture, and local geometry. Features for retrieval are discussed next, sorted by: accumulative and global features, salient points, object and shape features, signs, and structural combinations thereof. Similarity of pictures and objects in pictures is reviewed for each of the feature types, in close connection to the types and means of feedback the user of the systems is capable of giving by interaction. We briefly discuss aspects of system engineering: databases, system architecture, and evaluation. In the concluding section, we present our view on: the driving force of the field, the heritage from computer vision, the influence on computer vision, the role of similarity and of interaction, the need for databases, the problem of evaluation, and the role of the semantic gap.

/pdf/content-based-image-retrieval-at-the-end-of-the-early-years-q45iy9ejai.pdf

Content-based image retrieval at the end of the early years

Non-orthogonal multiple access (NOMA) is an essential enabling technology for the fifth-generation (5G) wireless networks to meet the heterogeneous demands on low latency, high reliability, massive connectivity, improved fairness, and high throughput. The key idea behind NOMA is to serve multiple users in the same resource block, such as a time slot, subcarrier, or spreading code. The NOMA principle is a general framework, and several recently proposed 5G multiple access schemes can be viewed as special cases. This survey provides an overview of the latest NOMA research and innovations as well as their applications. Thereby, the papers published in this special issue are put into the context of the existing literature. Future research challenges regarding NOMA in 5G and beyond are also discussed.

A Survey on Non-Orthogonal Multiple Access for 5G Networks: Research Challenges and Future Trends

This document provides updates to IEEE Std 802.16's MIB for the MAC, PHY and asso- ciated management procedures in order to accommodate recent extensions to the standard.

IEEE Standard for Local and Metropolitan Area Networks Part 16: Air Interface for Fixed Broadband Wireless Access Systems Draft Amendment: Management Information Base Extensions

One of the challenging issues for Orthogonal Frequency Division Multiplexing (OFDM) system is its high Peak-to-Average Power Ratio (PAPR). In this paper, we review and analysis different OFDM PAPR reduction techniques, based on computational complexity, bandwidth expansion, spectral spillage and performance. We also discuss some methods of PAPR reduction for multiuser OFDM broadband communication systems.

https://engold.ui.ac.ir/~sabahi/Advanced%20digital%20communication/An%20Overview%20Peak-to-Average%20Power%20Ratio%20Reduction%20Reduction%20Techniques%20for%20OFDM%20Signals.pdf

An Overview: Peak-to-Average Power Ratio Reduction Techniques for OFDM Signals

Orthogonal frequency-division multiplexing (OFDM) is an attractive transmission technique for high-bit-rate communication systems. One major drawback of OFDM is the high peak-to-average power ratio (PAPR) of the transmitter's output signal. The selected mapping (SLM) approach provides good performance for PAPR reduction, but it requires a bank of inverse fast Fourier transforms (IFFTs) to generate a set of candidate transmission signals, and this requirement usually results in high computational complexity. In this paper, we propose a kind of low-complexity conversions to replace the IFFT blocks in the conventional SLM method. Based on the proposed conversions, we develop two novel SLM schemes with much lower complexity than the conventional one; the first method uses only one IFFT block to generate the set of candidate signals, while the second one uses two IFFT blocks. Computer simulation results show that, as compared to the conventional SLM scheme, the first proposed approach has slightly worse PAPR reduction performance and the second proposed one reaches almost the same PAPR reduction performance.

Low-complexity selected mapping schemes for peak-to-average power ratio reduction in OFDM systems

Selected mapping (SLM) schemes are commonly employed to reduce the peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems. It has been shown that the computational complexity of the traditional SLM scheme can be substantially reduced by adopting conversion vectors obtained by using the inverse fast Fourier transform (IFFT) of the phase rotation vectors in place of the conventional IFFT operations [C.-L. Wang and Y. Ouyang, ?Low-Complexity Selected Mapping Schemes for Peak-to-Average Power Ratio Reduction in OFDM Systems,? IEEE Trans. Signal Process., vol. 53, no. 12, pp. 4652-4660, Dec. 2005]. To ensure that the elements of these phase rotation vectors have an equal magnitude, conversion vectors should have the form of a perfect sequence. This paper presents three novel classes of perfect sequence, each of which comprises certain base vectors and their cyclically shifted versions. Three novel low-complexity SLM schemes are then proposed based upon the unique structures of these perfect sequences. It is shown that while the PAPR reduction performances of the proposed schemes are marginally poorer than that of the traditional SLM scheme, the three schemes achieve a substantially lower computational complexity.

Novel Low-Complexity SLM Schemes for PAPR Reduction in OFDM Systems

This letter investigates power allocation for a downlink non-orthogonal multiple access system with a base station and two users. We first formulate an optimization problem for the single-input single-output (SISO) case in terms of power allocation between two users for maximizing the sum capacity under a total power constraint and a quality-of-service condition that the minimum rate requirement of each user is satisfied. Two closed-form solutions are subsequently derived. Then we extend the SISO solutions to a multiple-input multiple-output scenario. As compared to the optimal and the suboptimal approach presented in a recent work, the proposed schemes achieve close sum capacity performance with much lower computational complexity.

Power Allocation for a Downlink Non-Orthogonal Multiple Access System

The recursive computations in the MAP-based decoding of turbo codes usually introduce a significant amount of decoding delay. In this paper, we present a method for reducing the decoding delay by means of segmenting a block into several sub-blocks, which are partially overlapped. The proposed sub-block segmentation scheme allows for the parallel decoding of each component code by using several sub-block decoders. The number of steps for the recursive computations in each sub-block decoder is reduced to O(N/W), where W is the number of segmented sub-blocks. The decoding delay is approximately one-Wth that of a conventional MAP-based turbo-coding system. The cost paid is a slight degradation in bit error rate performance and a reasonable increase in hardware complexity.

A parallel decoding scheme for turbo codes

This paper presents two new systolic arrays to realize Euclid's algorithm for computing inverses and divisions in finite fields GF(2/sup m/) with the standard basis representation. One of these two schemes is parallel-in parallel-out, and the other is serial-in serial-out. The former employs O(m/sup 2/) area complexity to provide the maximum throughput in the sense of producing one result every clock cycle, while the latter achieves a throughput of one result per m clock cycles using O(m log,m) area complexity. Both of the proposed architectures are highly regular and, thus, well suited to VLSI implementation. As compared to existing related systolic architectures with the same throughput performance, the proposed parallel-in parallel-out scheme reduces the hardware complexity (and, thus, the area-time product) by a factor of O(m) and the proposed serial-in serial-out scheme by a factor of O(m/log/sub 2/m).

Chin-Liang Wang

Papers

Low-complexity selected mapping schemes for peak-to-average power ratio reduction in OFDM systems

Novel Low-Complexity SLM Schemes for PAPR Reduction in OFDM Systems

Power Allocation for a Downlink Non-Orthogonal Multiple Access System

A parallel decoding scheme for turbo codes

Systolic array implementation of Euclid's algorithm for inversion and division in GF(2/sup m/)