检索结果-内蒙古大学图书馆

Performance Comparison of repetition coding MIMO Optical Wireless Communications with Distinct Light Beams

SENSORS 2022年第3期22卷 1256-1256页

作者： Ding, Jupeng Lin, Chih Wang, Jintao Yang, Hui Wang, Lili Xinjiang Univ Sch Informat Sci & Engn Key Lab Signal Detect & Proc Xinjiang Uygur Auton Urumqi 830046 Peoples R China China Mobile Res Inst Beijing 100053 Peoples R China Tsinghua Univ Beijing Natl Res Ctr Informat Sci & Technol Dept Elect Engn Beijing 100084 Peoples R China Ludong Univ Sch Informat & Elect Engn Yantai 264025 Peoples R China

In current optical wireless communications (OWC) oriented research works, the various multiple input multiple output (MIMO) techniques are introduced and utilized to enhance the coverage performance. Objectively, this Lambertian light beam based MIMO research paradigm neglects the light beam diversity and the potential performance gains. In this work, the distinct non-Lambertian light beams of commercially available light emitting diodes (LEDs) were adopted to configure MIMO OWC links. Specifically, the homogenous and heterogeneous non-Lambertian MIMO configurations were constituted in typical indoor scenarios. Moreover, applying the repetition coding (RC) MIMO algorithm with low complexity, a spatial coverage performance comparison was made between the several above mentioned non-Lambertian configurations and the well-discussed Lambertian MIMO configuration. Numerical results illustrate that the homogeneous NSPW light beam configuration could provide a more than 30 dB average signal to noise ratio (SNR), while the achievable average SNR of the heterogeneous light beam configuration was up to 28.77 dB. On the other side, the counterpart of the Lambertian configuration achieved just about 27.00 dB. Objectively, this work paves the fundamental and essential way for the further design and optimization of MIMO OWC in this novel light beam dimension.

关键词： repetition coding MIMO optical wireless communications distinct light beams

来源：评论

学校读者我要写书评

暂无评论

A 10-state model for an AMC scheme with repetition coding in mobile wireless networks

引用

EURASIP JOURNAL ON WIRELESS COMMUNICATIONS AND NETWORKING 2013年第1期2013卷 1页

作者： Nguyen Quoc-Tuan Dinh-Thong Nguyen Lam Sinh Cong Vietnam Natl Univ Hanoi Vietnam Univ Technol Sydney Sydney NSW 2007 Australia

In modern broadband wireless access systems such as mobile worldwide interoperability for microwave access (WiMAX) and others, repetition coding is recommended for the lowest modulation level, in addition to the mandatory concatenated Reed-Solomon and convolutional code data coding, to protect vital control information from deep fades. This paper considers repetition coding as a time-diversity technique using maximum ratio combining (MRC) and proposes techniques to define and to calculate the repetition coding gain G (r) and its effect on bit error rate (BER) under the two fading conditions: correlated lognormal shadowing and composite Rayleigh-lognormal fading also known as Suzuki fading. A variable-rate, variable-power 10-state finite-state Markov channel (FSMC) model is proposed for the implementation of the adaptive modulation and coding (AMC) scheme in mobile WiMAX to maximize its spectral efficiency under constant power constraints in the two fading mechanisms. Apart from the proposed FSMC model, the paper also presents two other significant contributions: one is an innovative technique for accurate matching of moment generating functions, necessary for the estimation of the probability density function of the combiner's output signal-to-noise ratio, and the other is efficient and fast expressions using Gauss-Hermite quadrature approximation for the calculation of BER of QPSK signal using MRC diversity reception.

关键词： Lognormal fading Suzuki fading Gauss-Hermite polynomial Moment generating function WiMAX Adaptive modulation and coding repetition coding Finite-state Markov channel model

来源：评论

学校读者我要写书评

暂无评论

A Special Class of Quasi-cyclic Low-Density Parity-Check Codes Based on repetition Codes and Permutation Matrices

引用

PROBLEMS OF INFORMATION TRANSMISSION 2017年第3期53卷 229-241页

作者： Ivanov, F. I. Russian Acad Sci Kharkevich Inst Informat Transmiss Problems Moscow Russia

We propose a new ensemble of binary low-density parity-check codes with parity-check matrices based on repetition codes and permutation matrices. The proposed class of codes is a subensemble of quasi-cyclic codes. For the constructed ensemble, we obtain minimum distance estimates. We present simulation results for the proposed code constructions under the (Sum-Product) iterative decoding algorithm for transmission over an additive white Gaussian noise channel using binary phase-shift keying.

关键词： Binary phase shift keying repetition check matrix minimum distance permutation matrix AWGN channels Codes repetition coding Construction Specifications cyclic codes low density parity check codes Permutation

来源：评论

学校读者我要写书评

暂无评论

Performance Evaluation of Symbol-Wise XOR Based Bi-directional Relaying

引用

IEICE TRANSACTIONS ON COMMUNICATIONS 2009年第5期E92B卷 1796-1807页

作者： Wu, Jianming Miyazaki, Shunji Ohbuchi, Kazuhisa Taniguchi, Tomohiko YRP R&D Ctr Yokosuka Kanagawa 2390847 Japan

In this paper, we investigate the system performance of decode and forward based bi-directional relaying based on symbol-wise XOR operation. This technique gives more freedom in selecting the modulation and coding scheme at relay stations, and significantly relaxes the transmission bottleneck. However, the performance degradation occurs when the modulation orders of both links differ from each other. To mitigate such an impact, we exploit a repetition coding scheme in conjunction with a redundant modulation code scheme by overlapping MCS levels. To this end, a system level simulation proves that the proposed scheme achieves about 43% capacity gain over bit-wise XOR based bi-directional relaying and gives additional 10% gain over symbol-wise XOR based bidirectional relaying.

关键词： DF AF bi-directional relaying XOR redundant MCS repetition coding

来源：评论

学校读者我要写书评

暂无评论

A Comprehensive Study of repetition-Coded Protocols in Multi-User Multi-Relay Networks

引用

IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2009年第8期8卷 4329-4339页

作者： Wang, Chao Fan, Yijia Thompson, John S. Poor, H. Vincent Univ Edinburgh Inst Digital Commun Edinburgh EH9 3JL Midlothian Scotland Princeton Univ Dept Elect Engn Princeton NJ 08544 USA

The diversity-multiplexing tradeoff (DMT) performances of novel decode-and-forward (DF) relaying protocols for multi-source multi-relay cooperative networks are studied in this paper. For a strong-interference scenario and an isolated-relay scenario, the proposed protocols significantly improve diversity performance over direct source-destination transmissions by using a simple repetition coding strategy in relays. This is in addition to enhancing the multiplexing performance over standard DF protocols, which usually suffer from the half-duplex limitation at relays. Although the DMT performance of DF based relaying protocols is limited by the quality of source-relay links in principle, adaptive forms of the proposed protocols at the relays can transmit/not transmit according to source-relay transmissions and still provide link reliability and spectral efficiency advantages in general source-relay channel conditions.

关键词： Cooperative diversity diversity-multiplexing tradeoff (DMT) repetition coding

来源：评论

学校读者我要写书评

暂无评论

A Novel Linear Precoder Design for Reliable UL/DL Detection in TDD Cellular Networks

引用

IEEE TRANSACTIONS ON COMMUNICATIONS 2022年第12期70卷 8167-8180页

作者： Ibrahim, Mohamed Salah Hussain, Ahmed Sidiropoulos, Nicholas D. Univ Virginia Dept Elect & Comp Engn Charlottesville VA 22904 USA InterDigital Commun Conshohocken PA 19428 USA

The ever-growing demands on wireless connectivity, especially with the emergence of various data-intensive low-latency applications, require novel multiplexing solutions capable of reliably supporting high rates at low latency. Non-orthogonal time division duplex (TDD) coupled with multiuser detection can meet these emerging needs, provided that accurate channel state information is available. This paper proposes a new pilot-free TDD frame structure that allows designing highly effective multiuser decoders and precoders for uplink and downlink multicell systems, in an unsupervised manner. The key idea is that each user repeats and permutes its uplink data using a pre-assigned permutation code. Invoking canonical correlation analysis (CCA) at the serving BS on the two deinterleaved uplink blocks yields high quality CCA-based beamformers capable of both recovering the uplink and precoding the downlink user signals in a way that effectively mitigates interference. The paper includes a pilotless synchronization framework that leverages CCA to recover the timing and frequency offsets in an asynchronous multiuser MIMO setup, without using pilots. Simulations are used to study the performance of the proposed approach on a large-scale network with multiple users and cells, while laboratory experiments with a small-scale network of software radios are used to demonstrate that the approach works well in practice under common hardware imperfections.

关键词： Uplink Downlink Multiuser detection Correlation Codes MIMO communication Interference Time division duplex (TDD) downlink uplink multiuser detection multiple-input-multiple-output (MIMO) canonical correlation analysis (CCA) blind detection repetition coding identifiability software defined radio (SDR) synchronization

来源：评论

学校读者我要写书评

暂无评论

A robust and secure time-domain ICI canceller for OFDM based ubiquitous systems in time-varying multipath channels

引用

JOURNAL OF SUPERCOMPUTING 2008年第1期45卷 29-43页

作者： Seo, Jeong-Wook Yeo, Sang-Soo Park, Kyoo Seok Chang, Hang Bae Cho, Sung-Eon Kim, Dong-Ku Yonsei Univ Sch Elect & Elect Engn Seoul 120749 South Korea Kyushu Univ Dept Comp Sci & Commun Engn Fukuoka 812 Japan Kyungnam Univ Dept Comp Engn Masan 631701 Kyongnam South Korea Daejin Univ Dept Business Adm Gyeonggi 487711 South Korea Sunchon Natl Univ Dept Comp Sci & Commun Engn Sunchon 540742 Jeollanam South Korea

A robust and secure time-domain cancellation is proposed for inter-carrier interference (ICI) reduction in OFDM systems for ubiquitous environments. To cope with the problem of the conventional time-domain canceller, which does not work in deep fades, simple repetition (de)coding and modulation order increasing techniques are exploited in our proposal. The approximated repetition decoding provides reliable symbols in the regeneration operation, and the increased modulation order maintains the spectral efficiency. Simulation results indicate that the proposed method using 16QAM significantly improves the BER performance compared with the conventional method using QPSK, while the spectral efficiency is maintained. Moreover, the proposed method using 64QAM concurrently improves both the BER performance and the spectral efficiency.

关键词： OFDM intercarrier interference time-varying multipath channel repetition coding

来源：评论

学校读者我要写书评

暂无评论

Precise BER Analysis of repetition Coded OFDM Systems over Time- and Frequency-Selective Rayleigh Fading Channels

引用

IEICE TRANSACTIONS ON COMMUNICATIONS 2015年第1期E98B卷 88-98页

作者： Sasamori, Fumihito Asada, Satoru Takyu, Osamu Handa, Shiro Shinshu Univ Fac Engn Nagano 3808553 Japan Cent Japan Railway Co Nagoya Aichi 4506101 Japan

Orthogonal frequency division multiplexing (OFDM) has great advantages of high spectrum efficiency and robustness against multi-path fading. When the received signal is deeply suppressed by deep fading, path loss and shadowing, the received carrier powermust be increased in order to avoid degrading communication quality and provide high reliability at the cost of lower system throughput. A repetition coding is very attractive in providing the high reliability with simple configuration and the low decoding complexity of maximal ratio combining. In order to analytically confirm the effectiveness of repetition coded OFDM systems, we theoretically analyze the effect of increasing the number of repetitions (diversity branches) and acquiring both time and frequency diversity gain, and then derive a closed-form equation of average bit error rate (BER) to easily but precisely evaluate the performance.

关键词： OFDM repetition coding maximal ratio combining fading correlation closed-form equation

来源：评论

学校读者我要写书评

暂无评论

Effects of diversity schemes and correlated channels on OWC systems performance

引用

JOURNAL OF MODERN OPTICS 2017年第21期64卷 2298-2305页

作者： Alimi, Isiaka A. Shahpari, Ali Monteiro, Paulo P. Teixeira, Antonio L. Univ Aveiro Inst Telecomunicacoes DETI Aveiro Portugal

The salient features and advantages of free-space optical (FSO) system are very appealing for different applications in a number of communication network sectors. In spite of the advantages and diverse applications of FSO communication, its extensive use is hindered by the atmospheric turbulence-induced fading in real-life scenarios. Spatial diversity technique is one of effective means of mitigating turbulence-induced fading and, consequently, improves the system performance. In this paper, we study the spatial diversity schemes for mitigating turbulence-induced fading in the FSO communication systems using the bit error rate (BER) as a performance metric. The schemes considered are based on orthogonal space-time block codes and repetition codes (RCs). We derive simple approximate closed-form expressions for the error probability of the log-normal FSO links with intensity modulation and direct detection (IM/DD). Furthermore, we also investigate the effects of spatial correlation between the transmit apertures on the system performance. We achieve this using the exponential model for determining the correlations between the apertures. We observe that the proposed BER expressions are able to quantify the effects of spatial diversity schemes and spatial correlations on the system.

关键词： Atmospheric turbulence diversity techniques free-space optical communications lognormal channel repetition coding space-time coding spatial diversity

来源：评论

学校读者我要写书评

暂无评论

Performance Comparison of MIMO Techniques for Optical Wireless Communications in Indoor Environments

引用

IEEE TRANSACTIONS ON COMMUNICATIONS 2013年第2期61卷 733-742页

作者： Fath, Thilo Haas, Harald EADS Deutschland GmbH Innovat Works D-81663 Munich Germany Univ Edinburgh Inst Digital Commun Edinburgh EH9 3JL Midlothian Scotland

In this paper, we compare the performance of multiple-input-multiple-output (MIMO) techniques applied to indoor optical wireless communications (OWC) assuming line-of-sight (LOS) channel conditions. Specifically, several 4 x 4 setups with different transmitter spacings and different positions of the receiver array are considered. The following MIMO algorithms are considered: repetition coding (RC), Spatial Multiplexing (SMP) and Spatial Modulation (SM). Particularly, we develop a framework to analytically approximate the bit error ratios (BERs) of these schemes and verify the theoretical bounds by simulations. The results show that due to diversity gains, RC is robust to various transmitter-receiver alignments. However, as RC does not provide spatial multiplexing gains, it requires large signal constellation sizes to enable high spectral efficiencies. In contrast, SMP enables high data rates by exploiting multiplexing gains. In order to provide these gains, SMP needs sufficiently low channel correlation. SM is a combined MIMO and digital modulation technique. We show that SM is more robust to high channel correlation compared to SMP, while enabling larger spectral efficiency compared to RC. Moreover, we investigate the effect of induced power imbalance between the multiple transmitters. It is found that power imbalance can substantially improve the performance of both SMP and SM as it reduces channel correlation. In this context, we also show that blocking some of the links is an acceptable method to reduce channel correlation. Even though the blocking diminishes the received energy, it outweighs this degradation by providing improved channel conditions for SMP and SM. For example, blocking 4 of the 16 links of the 4 x 4 setup improves the BER performance of SMP by more than 20 dB, while the effective signal to noise ratio (SNR) is reduced by about 2 dB due to the blocking. Therefore, MIMO techniques can provide gains even under LOS conditions which provide only lit

关键词： MIMO optical wireless communications repetition coding spatial modulation spatial multiplexing

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：