检索结果-内蒙古大学图书馆

60th IEEE Vehicular Technology Conference

作者： Penther, B Bouttier, A Rollet, R Mitsubishi Elect Informat Technol Europe F-35708 Rennes France

ISBN: (纸本)0780385217

OFDM-based broadband Wireless LAN standards like IEEE802.11a or ETS1/BRAN HiperLAN/2 rely on adaptive modulation and coding for link adaptation. This paper presents a novel link adaptation metric that enables a better prediction of the BER/PER performance without a priori knowledge on the channel profile. This metric computes statistics from the output of the equalizer in order to take into account the channel noise and multipath fading conditions at the same time. Simulation and experiments show that the proposed scheme is able to improve the overall system performance with a reasonable implementation cost.

关键词： adaptive modulation and coding link adaption WLAN HiperLAN/2.IEEE802.11a Qos

来源：评论

学校读者我要写书评

暂无评论

adaptive Communication using Softcomputing Techniques

Adaptive Communication using Softcomputing Techniques

引用

International Conference of Soft Computing and Pattern Recognition (SoCPaR)

作者： Atta-ur-Rahman Qureshi, Ijaz Mansoor Salam, Muhammad Hammad Muzaffar, Muhammad Zeeshan PMAS Arid Agr Univ Rawalpindi Barani Inst Informat Technol Rawalpindi Pakistan Inst Signals Syst & Soft Comp ISSS Islamabad Pakistan Air Univ Dept Elect Engn Islamabad Pakistan ISRA Univ SEAS Islamabad Pakistan Univ Lahore SIT Islamabad Pakistan

ISBN: (纸本)9781479934003

adaptive communication has gained attention of almost every recent communication system because of its rate enhancement and context aware features. In this concept, different transmission parameters like transmit power, forward error correcting (FEC) code rate and modulation scheme are adaptively chosen according to the channel state information. Consequently, that set of transmission parameters is chosen that maximizes the channel capacity as well as fulfills the power and bit error rate constraints. Finding the optimum value of the said parameters is a highly non-linear problem with huge search space for solution. In this paper, we have investigated Ant Colony Optimization (ACO) in conjunction with a fuzzy rule base system (SA-FRBS) for adaptive coding, modulation and power in an orthogonal frequency division multiplexing environment. Proposed scheme is compared with Simulated Annealing and FRBS (SA-FRBS) assisted adaptive coding modulation and power scheme as well as with the fixed power scheme. Superiority of proposed scheme is shown by the simulations.

关键词： component ACO Simulated Annealing OFDM FRBS BER adaptive modulation and coding

来源：评论

学校读者我要写书评

暂无评论

DYNAMIC RATE ADAPTATION AND MULTIUSER DOWNLINK BEAMFORMING USING MIXED INTEGER CONIC PROGRAMMING

DYNAMIC RATE ADAPTATION AND MULTIUSER DOWNLINK BEAMFORMING U...

引用

20th European Signal Processing Conference (EUSIPCO)

作者： Cheng, Yong Philipp, Anne Pesavento, Marius Tech Univ Darmstadt Commun Syst Grp Darmstadt Germany Tech Univ Darmstadt Dept Mat Darmstadt Germany

ISBN: (纸本)9781467310680

This paper considers jointly optimized rate adaptation and beamforming (JRAB) to achieve maximum weighted sum-rate in a multiuser downlink network. In our approach the rate adaptation consists in assigning modulation and coding schemes (MCSs) for the users which are modeled by multiple-choice constraints. The challenge of the problem lies in its combinatorial nature of the MCS selection process. We address the JRAB problem within the mixed integer second order cone programming (MI-SOCP) framework. We propose a convenient MI-SOCP reformulation that is specifically suitable to reduce the run-time in branch-and-bound (BB) methods. Further, a preprocessing step and a novel branching prioritizing principle (BPP) are introduced to speed up the BB type solutions. To facilitate applications in large systems, a fast heuristic algorithm is developed. We show via simulations that the improved MI-SOCP formulation and the BPP can significantly reduce the run-time for solving the JRAB problem with BB. Numeric results also show that the heuristic algorithm yields weighted sum-rates that are larger than that computed by the state-of-the-art MI-SOCP solver IBM ILOG CPLEX under the given run-time limitations.

关键词： Dynamic rate adaptation adaptive modulation and coding Multiuser downlink beamforming Joint optimization Mixed integer conic programming

来源：评论

学校读者我要写书评

暂无评论

Dynamic Flow Control for Big Data Transmissions toward 5G Multi-Hop Relaying Mobile Networks 7

Dynamic Flow Control for Big Data Transmissions toward 5G Mu...

引用

IEEE 7th International Symposium on Cloud and Service Computing (IEEE SC2)

作者： Chang, Ben-Jye Li, Yi-Hsuan Chen, Shin-Pin Liang, Ying-Hsin Natl Yunlin Univ Sci & Technol Dept Comp Sci & Informat Engn Touliu Yunlin Taiwan Nan Kai Univ Technol Dept Multimedia Animat & Applicat Caotun Nantou Taiwan

ISBN: (纸本)9781538658628

Cloud computing provides various diverse services for users accessing big data through high data rate cellular networks, e.g., LTE-A, IEEE 802.11ac, etc. Although LTE-A supports very high data rate, multi-hop relaying, and cooperative transmission, LTE-A suffers from high interference, path loss, high mobility, etc. Additionally, the accesses of cloud computing services need the transport layer protocols (e.g., TCP, UDP, and streaming) for achieving end-to-end transmissions. Clearly, the transmission QoS is significantly degraded when the big data transmissions are done through the TCP protocol over a high interference LTE-A environment. Thus, this paper proposes a cross-layer-based adaptive TCP algorithm to gather the LTE-A network states (e.g., AMC, CQI, relay link state, available bandwidth, etc.), and then feeds the state information back to the TCP sender for accurately executing the network congestion control of TCP. As a result, by using the accurate TCP congestion window (cwnd) under a high interference LTE-A, the number of timeouts and packet losses are significantly decreased. Numerical results demonstrate that the proposed approach outperforms the compared approaches in goodput and fairness, especially in high interference environment. Especially, the goodput of the proposed approach is 139.42% higher than that of NewReno The results can justify the claims of the proposed approach.

关键词： Toward 5G LTE-A Multiple-hop relaying cross-layer adaptive modulation and coding congestion control TCP reliable transmission

来源：评论

学校读者我要写书评

暂无评论

Research of Link Adaptation Technology and Solutions in Wireless Communication Network

Research of Link Adaptation Technology and Solutions in Wire...

引用

2nd International Conference on Measurement, Instrumentation and Automation (ICMIA 2013)

作者： Cao, Lu Xu, Ying Wang, Tianlei Wuyi Univ Sch Informat & Engn Jiangmen Peoples R China

ISBN: (纸本)9783037857519

With the rapid growth of the demand for wireless data services, it becomes a hotspot in the field of mobile communication to maximize data transfer rate on the limited bandwidth. Link adaptation technology has a strong advantage in improving the data transfer rate and the spectrum utilization rate, thus becoming one of the key technologies in current and future mobile communication systems. This paper aims to study the adaptive technology of the wireless link, emphasizing on the basic principles and existing implementations of the adaptive modulation and coding (AMC) and the hybrid-automatic repeat request (HARQ) which are both mainstream link adaptive technologies. Finally, a new link adaptation technology implementation is given by combining the advantages of AMC and HARQ.

关键词： Link Adaptation adaptive modulation and coding Hybrid-automatic repeat request

来源：评论

学校读者我要写书评

暂无评论

Efficient Link Adaptation in OFDM Systems using a Hybrid Intelligent Technique 13

Efficient Link Adaptation in OFDM Systems using a Hybrid Int...

引用

13th International Conference on Hybrid Intelligent Systems (HIS)

作者： Atta-ur-Rahman Qureshi, Ijaz Mansoor Salam, Muhammad Hammad Naseem, Muhammad Tahir Barani Inst Informat Technol Rawalpindi Pakistan Inst Signals Syst & Soft Comp ISSS Islamabad Pakistan Air Univ Dept Elect Engn Islamabad Pakistan Univ Lahore Islamabad Pakistan

ISBN: (纸本)9781479924394

adaptive communication for rate enhancement and link survival is a recent area of interest. In adaptive communication, transmission parameters like transmit power, code rate and modulation scheme are chosen in an adaptive manner to match the link conditions and quality of service demand at that transmission interval. But this is a highly non linear phenomenon and a constrained optimization problem. In this paper, we have investigated Simulated Annealing algorithm in conjunction with a fuzzy rule base system (SA-FRBS) for adaptive coding, modulation and power in an orthogonal frequency division multiplexing environment. The cases of fixed and adaptive communication are compared and results are shown through the simulations.

关键词： component Sinmlated Annealing OFDM FRBS BER adaptive modulation and coding

来源：评论

学校读者我要写书评

暂无评论

FBL (Flexible Block-wise Loading) Algorithm for Effective Resource Allocation in OFDMA Systems with Reduced Uplink Feedback Information

FBL (Flexible Block-wise Loading) Algorithm for Effective Re...

引用

19th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications

作者： Sun, TaeHyoung Wang, YuPeng Chang, KyungHi Inha Univ Grad Sch IT&T Inchon South Korea

ISBN: (纸本)9781424426430

AMC (adaptive modulation and coding) is a well-known technique that selects a suitable modulation level and coding rate according to the user's channel quality. The utilization of AMC in DL (downlink) requires the DL channel information of each user to properly select the MCS (modulation and coding Scheme) level. However, under a practical OFDMA system environment, it is unsuitable to feed back all the channel information over the whole frequency resources due to the limited uplink bandwidth. In this paper, to optimize the performance of the AMC system we propose a FBL (Flexible Block-Wise Loading) algorithm) combined with a novel CQI (Channel Quality Information) feedback scheme with a reduced number of required bit. The proposed FBI algorithm dynamically allocates groups of sub-carriers to each user based on the channel quality information in a newly defined feedback signal format, thereby improving the sector throughput and outage probability performance.

关键词： OFDMA adaptive modulation and coding FBL CQI Reduction

来源：评论

学校读者我要写书评

暂无评论

Mitigating Interference in Content Delivery Networks by Spatial Signal Alignment: The Approach of Shot-Noise Ratio

引用

IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2018年第4期17卷 2305-2318页

作者： Liu, Dongzhu Huang, Kaibin Univ Hong Kong Dept Elect & Elect Engn Hong Kong Hong Kong Peoples R China

Multimedia content, especially videos, is expected to dominate data traffic in next-generation mobile networks. Caching popular content at the network edge, namely content helpers (base stations and access points), has emerged as a solution for low-latency content delivery. Compared with traditional wireless communication, content delivery has a key characteristic that many signals coexisting in the air carry identical popular content. However, they can interfere with each other at a receiver if their modulation-and-coding (MAC) schemes are adapted to individual channels following the classic approach. To address this issue, we present a novel idea of content adaptive MAC (CAMAC) where adapting MAC schemes to content ensures that all signals carrying identical content are encoded using an identical MAC scheme to achieve spatial MAC alignment. Consequently, interference can be harnessed as signals to improve the reliability of wireless delivery. In the remaining part of the paper, we focus on quantifying the gain that CAMAC can bring to a content-delivery network by using a stochastic-geometry model. Specifically, content helpers are distributed as a Poisson point process and each of them transmits a file from a content database based on a given popularity distribution. Given a fixed threshold on the signal-to-interference ratio for successful transmission, it is discovered that the successful content-delivery probability is closely related to the distribution of the ratio of two independent shot noise processes, named a shot-noise ratio. The distribution itself is an open mathematical problem that we tackle in this work. Using stable-distribution theory and tools from stochastic geometry, the distribution function is derived in closed form. Extending the result in the context of content-delivery networks with CAMAC yields the content-delivery probability in different closed forms. In addition, the gain in the probability due to CAMAC is shown to grow with the level

关键词： Content delivery cache-enabled network adaptive modulation and coding stochastic geometry shot noise ratio

来源：评论

学校读者我要写书评

暂无评论

Constellation rearrangement: Enhancement for multilevel modulation formats and transmit diversity

引用

WIRELESS PERSONAL COMMUNICATIONS 2004年第1-2期29卷 35-45页

作者： Wengerter, C Von Elbwart, AGE Seidel, E Panason Multimedia commun European Lab D-63225 Langen Germany

Radio link adaptivity will be a key feature of the air interfaces of future mobile communication systems. This adaptivity includes techniques such as fast scheduling, hybrid ARQ, transmit diversity and adaptive modulation and coding. The performance of adaptive modulation generally suffers from the power inefficiencies of multilevel modulation formats. This is due to the variations in bit reliabilities caused by the bit-mapping onto the signal constellation. This article presents a concept, called constellation rearrangement (CoRe), which improves the multilevel modulation power efficiency by the joint application with transmit diversity schemes. It is shown by a theoretical analysis for 16-QAM that the presented concept can equalize variations in bit reliabilities by employing different mapping rules for the transmission over the diversity branches. This significantly improves the receiver block error rate performance and, hence, the performance of the adaptive modulation and coding. This is proven by simulations at link-level in a multicarrier CDMA system for AWGN and fading channels employing turbo coded transmission.

关键词： constellation rearrangement radio link adaptivity adaptive modulation and coding transmit diversity multilevel modulation quadrature amplitude modulation turbo coding soft demodulation multicarrier CDMA

来源：评论

学校读者我要写书评

暂无评论

Performance Evaluation of AMC turbo Coded OFDM for 3GPP Long Term Evolution downlink system

Performance Evaluation of AMC turbo Coded OFDM for 3GPP Long...

引用

International Conference on Multimedia Computing and Systems (ICMCS)

作者： El Makhtari, Salima Moussaoui, Mohamed Samadi, Hassan Ecole Natl Sci Appl Lab Technol Informat & Commun Tangier Morocco

ISBN: (纸本)9781467315203

This paper presents a performance evaluation of OFDM LTE downlink physical layer according to the latest 3GPP specifications. Particularly, adaptive modulation and coding (AMC) is described and analyzed. This is in conjunction with the turbo decoding algorithm Max-Log-Maximum A Posteriori (Max-Log-MAP) used in soft input soft output (SISO) decoders. The performance analysis is carried out in terms of bit error rate (BER) and throughput by varying parameters such as signal to noise ratio (SNR), modulation schemes, coding rates and decoding iterations number.

关键词： 3GPP LTE OFDM Turbo coding adaptive modulation and coding Throughput BER

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：