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walsh code assignment and data structure for variable data rate communications

IEEE TRANSACTIONS ON COMMUNICATIONS 2008年第3期56卷 339-343页

作者： Wang, Michael Mao Brown, Tyler Fleming, Philip Xu, Hua Qualcomm Inc San Diego CA 92121 USA Motorola Inc Arlighton Heights IL 60004 USA

In digital communication systems, variable-length walsh codes, also called orthogonal variable spreading factor codes, are used to support simultaneous variable-rate data transmission. This paper describes algorithms for dynamic variable-length walsh code assignment. Optimal assignment criterion is derived and an efficient data structure for maintaining variable-length walsh codes is introduced. The benefits of code reallocation are also studied. Performance is evaluated via simulation.

关键词： walsh code orthogonal variable spreading factor (OVSF) code orthogonal channelization code maximum-weight criterion variable data rate communications

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High Bandwidth Efficiency and Low Power Consumption walsh code Implementation Methods for Body Channel Communication

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IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES 2014年第9期62卷 1867-1878页

作者： Ho, Chee Keong Cheong, Jia Hao Lee, Junghyup Kulkarni, Vishal Li, Peng Liu, Xin Je, Minkyu ASTAR Inst Microelect Singapore 117685 Singapore Daegu Gyeongbuk Inst Sci & Technol Dept Informat & Commun Engn Taegu 711873 South Korea

With the growing number of wearable devices and applications, there is an increasing need for a flexible body channel communication (BCC) system that supports both scalable data rate and low power operation. In this paper, a highly flexible frequency-selective digital transmission (FSDT) transmitter that supports both data scalability and low power operation with the aid of two novel implementation methods is presented. In an FSDT system, data rate is limited by the number of walsh spreading codes available for use in the optimal body channel band of 40-80 MHz. The first method overcomes this limitation by applying multi-level baseband coding scheme to a carrierless FSDT system to enhance the bandwidth efficiency and to support a data rate of 60 Mb/s within a 40-MHz bandwidth. The proposed multi-level coded FSDT system achieves six times higher data rate as compared to other BCC systems. The second novel implementation method lies in the use of harmonic frequencies of a walsh encoded FSDT system that allows the BCC system to operate in the optimal channel bandwidth between 40-80 MHz with half the clock frequency. Halving the clock frequency results in a power consumption reduction of 32%. The transmitter was fabricated in a 65-nm CMOS process. It occupies a core area of 0.24 x 0.3 mm(2). When operating under a 60-Mb/s data-rate mode, the transmitter consumes 1.85mW and it consumes only 1.26 mW when operating under a 5-Mb/s data-rate mode.

关键词： Frequency-selective digital transmission (FSDT) harmonic frequency human body communication synchronization walsh code wireless

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walsh code Soft Spread Spectrum Multi-tone Interference Suppression Algorithm 4

Walsh Code Soft Spread Spectrum Multi-tone Interference Supp...

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4th International Conference on Communication and Information Systems (ICCIS)

作者： Zhang, Danna Liu, Zhongfei Yang, Xiaojing Zhang, Yu Natl Univ Def Technol Coll Elect Countermeasures Hefei Anhui Peoples R China

ISBN: (纸本)9781728162973

For the difficulty of multi-tone interference suppression for adaptive filters based on least mean square criterion, an improved algorithm is proposed to realize multi-tone interference suppression for walsh code soft spread spectrum signals. The algorithm firstly decomposes the received signal by empirical mode, and obtains a series of intrinsic mode function with monophonic interference. Then, the adaptive filters based on least mean square is performed on the intrinsic mode function to obtain multi-tone interference. Finally, the walsh code soft spread spectrum signal is realized Multi-tone interference suppression. The simulation results show that the algorithm can realize the multi-tone interference suppression of walsh code soft spread spectrum signal within a certain SNR range.

关键词： walsh code soft spread spectrum adaptive filters empirical mode decomposition multi-tone

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Synchronization Algorithms Applied to code Division Multiplexing Link Based on the walsh code of Ground Based Beamforming 5th

Synchronization Algorithms Applied to Code Division Multiple...

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5th International Conference on Electronics, Communications and Networks (CECNet)

作者： Wan, Wei Tang, Le Tu, Hang Beijing Inst Technol Sch Informat & Elect Beijing Peoples R China

ISBN: (纸本)9789811007408;9789811007385

A synchronization algorithm that applies to the code Division Multiplexing (CDM) link based on walsh code is proposed to solve problems of pre-existing algorithms based on pilot. The algorithm proposed by this paper achieved blind synchronization without pilot, and improved applicability at low SNR by incoherent accumulation. The simulation results indicate that the proposed algorithm achieves high synchronization precision and acceptable synchronization time, and can thus be applied to CDM links based on walsh codes of GBBF (Ground Based Beam forming).

关键词： walsh code GBBF Synchronization CDM

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A High Data Rate Solution for Multi-Carrier DCSK

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INTERNATIONAL JOURNAL OF BIFURCATION AND CHAOS 2025年第5期35卷

作者： Yu, Bin Jiang, Guo-Ping Yang, Hua Jia, Ya-Qiong Liao, Hao Nanjing Univ Posts & Telecommun Sch Comp Sci Nanjing 210023 Peoples R China Hunan Inst Technol Sch Elect Informat Engn Hengyang 421002 Peoples R China Nanjing Univ Posts & Telecommun Sch Automat Nanjing 210023 Peoples R China Nanjing Univ Posts & Telecommun Sch Elect & Opt Engn Nanjing 210023 Peoples R China

A high data rate multi-carrier differential chaos shift keying system with hybrid index modulation, referred to as HDR-HIM-MC-DCSK, is proposed in this paper. In the proposed system, multiple data-bearing wavelets are parallelly transmitted with one reference signal. Different walsh codes are utilized for separating these data-bearing wavelets. Some subcarriers are used for hybrid index modulation, in which the chaotic signal and its Hilbert transform are generated for representing the active and inactive subcarriers. In addition, the analytical Bit-Error-Rate (BER) expressions of the proposed HDR-HIM-MC-DCSK system are derived over the AWGN and the multipath Rayleigh fading channels. The hardware complexity, computational complexity, energy efficiency, spectral efficiency and data rate of the proposed system are analyzed. The analytical accuracy and the advantages of the proposed system are verified by relevant simulations.

关键词： Differential chaos shift keying hybrid index modulation high data rate bit error rate walsh code

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Synchronous walsh-based bipolar-bipolar code for, CDMA passive optical networks

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JOURNAL OF LIGHTWAVE TECHNOLOGY 2007年第8期25卷 1910-1917页

作者： Hu, Hsiao-Wei Chen, Hung-Ta Yang, Guu-Chang Kwong, Wing C. Natl Chung Hsing Univ Dept Elect Engn Taichung 402 Taiwan Hofstra Univ Dept Engn Hempstead NY 11549 USA

We propose a "synchronous" wavelength-time optical code-division multiple access (CDMA) scheme using 2-D walsh-based bipolar-bipolar code, in which walsh code sequences are used for time spreading, in place of Barker sequences used in our previously proposed "asynchronous" bipolar-bipolar code. The new synchronous coding scheme supports larger cardinality and better performance than the asynchronous scheme because walsh code has a larger cardinality than Barker sequences and has a zero cross-correlational property at the expense of system synchronization. One potential application is future CDMA-based passive optical networks, in which synchronous downstream traffic uses the walsh-based bipolar-bipolar code and asynchronous upstream traffic uses the Barker-based counterpart. Since the new code is modified from the original code, the same hardware can be used for both directions of traffic.

关键词： bipolar-bipolar code optical code-division multiple access (OCDMA) walsh code

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Novel multispectral face descriptor using orthogonal walsh codes

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IET IMAGE PROCESSING 2019年第7期13卷 1097-1104页

作者： Cevik, Nazife Cevik, Taner Gurhanl, Ahmet, I Istanbul Arel Univ Dept Comp Engn Istanbul Turkey Istanbul Aydin Univ Dept Software Engn Istanbul Turkey Istanbul Aydin Univ Dept Comp Engn Istanbul Turkey

This paper proposes a novel high-performance multispectral local descriptor that uses orthogonal walsh codes during the generation of the discriminative feature set. Rotational variance and noise are compelling factors that significantly affect the distinctive performance of a facial identifier. The descriptor proposed in this article handles these challenges favourably sacrificing any distinctive performance. Orthogonal walsh codes are used during the generation of the local descriptor. A walsh code is assigned to each neighbour of a reference pixel. Before the assignment of an orthogonal code to each neighbouring pixel, these pixels are sorted in ascending order that consolidates the robustness of the method against rotational variances. Almost all methods proposed so far focus on grayscale images. However, colour bands contain important information about the relationship between pixels. Therefore, authors' method considers RGB colour bands of pixels to improve distinctive performance. The results of extensive simulations show the remarkable and competitive performance of the proposed method regarding recognition accuracy and robustness against rotational variances as well as noise effects.

关键词： image colour analysis face recognition feature extraction orthogonal codes novel multispectral face descriptor orthogonal walsh codes novel high-performance multispectral local descriptor noise distinctive performance walsh code orthogonal code neighbouring pixel pixels rotational variances

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OCPM: Ortho code privacy mechanism in smart grid using ring communication architecture

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AD HOC NETWORKS 2014年第Nov.期22卷 93-108页

作者： Li, Shi Choi, Kyung Chae, Kijoon Ewha Womans Univ Dept Comp Sci & Engn Seoul South Korea

Various privacy problems routinely arise when the control center manages the power distribution based on customers' power usage which is automatically transmitted by smart meters in the smart grid system. Therefore an improved customers' privacy protection architecture called "Ring Communication Architecture (RCA)" is proposed. In this paper, we propose a novel mechanism focusing on the privacy issues by means of an orthogonal code ("ortho code") based on the RCA. Our mechanism is performed in two processes: measurement transmission process and payment transmission process. During measurement transmission process, the data measured by smart meters are encrypted by using ortho codes and aggregated in the RCA and then sent to the utility through an aggregator. The utility can decrypt each measurement from the receiving aggregation data and charge customers in payment transmission process without realizing the privacy of customers. By the quantitative and qualitative analysis of the performance and security, the proposed mechanism can achieve low power consumption and efficient encryption as well as prevent snooping attack, modification attack, masquerading attack, and replaying attack which threaten the smart grid. (C) 2014 Published by Elsevier B.V.

关键词： Privacy Ortho code walsh code Smart meter Smart grid

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code-Domain Multiplexing for Shared IF/LO Interfaces in Millimeter-Wave MIMO Arrays

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IEEE JOURNAL OF SOLID-STATE CIRCUITS 2020年第5期55卷 1270-1281页

作者： Johnson, Manoj Dascurcu, Armagan Zhan, Kai Galioglu, Arman Adepu, Naresh Kumar Jain, Sanket Krishnaswamy, Harish Natarajan, Arun S. Oregon State Univ Sch Elect Engn & Comp Sci Corvallis OR 97330 USA Columbia Univ Dept Elect Engn New York NY 10027 USA Oregon State Univ Sch Elect Engn & Comp Sci Corvallis OR 97331 USA Qualcomm San Diego CA 92121 USA Columbia Univ Dept Elect Engn New York NY 10027 USA Univ Calif San Diego Dept Elect & Comp Engn La Jolla CA 92093 USA Apple Austin TX USA

Millimeter-wave (mm-wave) multi-input-multi-output (MIMO) systems with the digitization of every element enable spatial multiplexing, virtual arrays for radar, and digital beamforming for high mobility scenarios. However, per-element digitization results in a formidable I/O challenge in large-scale tiled MIMO mm-wave arrays. This article analyzes a code-domain approach to multiplex signals from different elements as well as the LO on a single interface. System considerations are presented, and the approach is demonstrated through a 28 GHz four-element MIMO receiver in 65-nm CMOS. Measurements show the feasibility of digital beamforming after de-multiplexing of the baseband signals from the IF/LO interface. Each element in the array achieves 16-dB conversion gain while consuming 60 mA from 1.2 V. The IC occupies 5.75 mm(2) in 65-nm CMOS, achieving small size and compatibility with $\lambda /2 \times \lambda /2$ antenna spacing due to the absence of phase shifters/combiners required in phased arrays.

关键词： Multiplexing MIMO communication Phased arrays Millimeter wave radar Bandwidth Correlation Array signal processing code-domain input matching multi-input multi-output (MIMO) millimeter-wave (mm-wave) arrays phased arrays walsh code

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code-Shifted Reference for Internally coded Time Hopping UWB Communication System

Code-Shifted Reference for Internally Coded Time Hopping UWB...

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International Symposium on Telecommunications

作者： Sedaghat, M. A. Kenari, M. Nasiri Sharif Univ Technol Dept Elect Engn Tehran Iran

ISBN: (纸本)9781424427505

In this paper, we consider a code-shifted reference (CSR) for the previously introduced internally coded time hopping UWB communication systems in order to avoid channel estimation. We evaluate the performance of our proposed scheme and compare the results with those of the uncoded coded-shifted reference (CSR) UWB system. Our numerical results show the substantial performance improvement when using the proposed scheme compared to the uncoded CSR system.

关键词： Ultra-wideband impulse radio transmitted reference internal coding code-shifted reference walsh code

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