检索结果-内蒙古大学图书馆

Delay constrained throughput optimisation with imperfect CSI using discrete adaptive power

INTERNATIONAL JOURNAL OF ELECTRONICS 2018年第12期105卷 2033-2051页

作者： Taki, Mehrdad Nezafati, Mohammad B. Univ Qom Dept Elect Engn Qom Iran Inst Res Fundamental Sci Tehran Iran

Link adaptation is an effective tool to overcome fading effects in wireless links. However, time-varying adaptive transmission rate leads to queueing delay, and moreover, in practise, imperfect channel state information (CSI) is available for the transmitter to adapt its transmission rate and power. This article aims to consider practical constraints to enhance the link adaptation scheme. We reformulate and optimise buffer delay constrained throughput of a wireless link based on outdated noisy CSI. Discrete power adaptation is proposed, in which a limited number of feedback bits (just the index of transmission power level) is required, while the performance is improved compared to the constant power and is close to continuous adaptive power. A unified scheme is set-up, where constant, discrete or continuous adaptive power transmission is utilised considering average or instantaneous bit error rate constraints based on imperfect CSI. The effectiveness of our designs is evaluated by numerical evaluations.

关键词： Link adaptation cross-layer design adaptive modulation and coding delay constrained throughput outdated noisy CSI

来源：评论

学校读者我要写书评

暂无评论

Dynamic resource allocation in OFDM systems using DE and FRBS

引用

JOURNAL OF INTELLIGENT & FUZZY SYSTEMS 2014年第4期26卷 2035-2046页

作者： Atta-ur-Rahman Qureshi, Ijaz Mansoor Malik, Aqdas Naveed Naseem, Muhammad Tahir ISRA Univ SEAS Islamabad Pakistan Univ Air Dept Elect Engn Islamabad Pakistan

Dynamic allocation of the resources for optimum utilization is one of the most important fields of study in engineering as well as other disciplines nowadays. In this process the available resources are allocated in such a way that these resources are maximally utilized to enhance the overall system throughput while satisfying certain constraints at the same time. In this paper a similar constrained optimization problem is focused for Orthogonal Frequency Division Multiplexing (OFDM) environment, in which the transmission parameters namely code rate, modulation scheme and power are adapted in such a way that overall system data rate is maximized with a constrained bit error rate and transmit power. This is a highly non-linear problem that cannot be solved by ordinary linear optimization techniques. A Fuzzy Rule Base System (FRBS) is proposed for adapting the code rate and modulation scheme while Differential Evolution is used for choosing the optimum power vector. The proposed scheme is compared with other schemes.

关键词： Differential evolution OFDM FRBS BER adaptive modulation and coding optimum power vector

来源：评论

学校读者我要写书评

暂无评论

Integrated scheduling and link adaptation for heterogeneous networks: design and performance analysis

引用

INTERNATIONAL JOURNAL OF ELECTRONICS 2020年第7期107卷 1098-1126页

作者： Taki, Mehrdad Nezafati, Mohammad Bagher Univ Qom Dept Elect Engn Qom Iran Inst Res Fundamental Sci Tehran Iran

This paper presents novel integrated scheduling and link adaptation (ISLA) schemes for links which have a common spectrum and possibly different rates and reliability constraints. We consider the problem of weighted sum average rate maximisation of wireless links. In an orthogonal transmission system, a link is selected using instantaneous signal-to-noise (SNR) of all the links, and its rate and power are set in a jointly optimised manner. To demonstrate the effectiveness of the proposed approach, we analyse ISLA schemes with continuous rate adaptation using constant or adaptive transmission powers. ISLA schemes are designed in similar settings for practical discrete rate-adaptive systems using adaptive modulation and coding. To this end, a design framework is presented, which relies on a partitioning of space of links' SNRs into regions, similar to structured vector quantisation. Within this framework, a particular ISLA design with high performance and polynomial complexity is suggested. The proposed schemes are designed before the start of the transmission, based on closed-form solutions, and can easily be applied to multiple access or broadcast networks. We also analyse several schemes for comparison, which employ modified Round-Robin, opportunistic scheduling or online generalised scheduling. Numerical results demonstrate how the proposed ISLA schemes outperform the benchmark schemes and effectively meet various user requirements.(1)

关键词： Cross-layer design and optimisation adaptive modulation and coding rate and power allocation optimised scheduling link adaptation

来源：评论

学校读者我要写书评

暂无评论

adaptive Resource Allocation for Scalable Video Transmission over OFDMA Systems

引用

WIRELESS PERSONAL COMMUNICATIONS 2016年第1期91卷 79-99页

作者： Yang, Zan Zhao, Yuping Minist Transport Transport Planning & Res Inst Beijing 100028 Peoples R China Peking Univ Sch Elect Engn & Comp Sci State Key Lab Adv Opt Commun Syst & Networks Beijing 100871 Peoples R China

We propose an adaptive resource allocation algorithm for scalable H.264 video transmission over orthogonal frequency-division multiple-access (OFDMA) systems. The algorithm explores the scalability of the video codec and the multiuser diversity of OFDMA systems to achieve enhanced efficiency and video quality. We use the peak signal-to-noise ratio (PSNR) as the measure metric of video quality, and jointly optimize the video layer extraction and radio resource allocation, considering the heterogeneity of video sources and channel conditions. Given the fact that different quality layers of the video have different importance, an adaptive modulation and coding scheme is proposed where a fixed coding rate is used for each quality layer, and unequal error protection is implemented for different layers. We also propose a subcarrier allocation algorithm to assign subcarriers for different layers of different users' videos to maximize the average PSNR of users while satisfying the base layer requirement. The proposed resource allocation algorithm has a low complexity and is suitable for practical implementations. We further develop an end-to-end simulation testbed to demonstrate the effectiveness of the proposed transmission scheme.

关键词： Scalable video H.264 OFDMA adaptive modulation and coding Subcarrier allocation

来源：评论

学校读者我要写书评

暂无评论

Bandwidth-efficient bit-interleaved coded cooperative communications

引用

WIRELESS PERSONAL COMMUNICATIONS 2008年第3期46卷 247-268页

作者： Nguyen, Hieu T. Nguyen, Ha H. Le-Ngoc, Tho Univ Saskatchewan Dept Elect & Comp Engn Saskatoon SK S7N 5A9 Canada McGill Univ Dept Elect & Comp Engn Montreal PQ H3A 2A7 Canada

A cooperative coding scheme using M-ary modulation for high spectral efficiency and repetitive information transmission for diversity improvement is proposed. The encoder is a parallel concatenation of two bit-interleaved coded M-ary modulators (BICM) with scalable repetition of information symbols. As a result, the fraction of repeated information and the spectral efficiency of M-ary modulation can be used for bandwidth-performance tradeoff. Performance analysis is carried out to verify the performance advantage of the proposed system. In particular, analytical and simulation results in various block fading scenarios show that for a given bandwidth efficiency, a proper selection of the fraction of repeated information and the spectral efficiency of M-ary modulation can provide a large performance improvement.

关键词： cooperative communications coded modulation performance analysis block fading channel adaptive modulation and coding

来源：评论

学校读者我要写书评

暂无评论

Dynamic Fractional Frequency Reuse (DFFR) with AMC and Random Access in WiMAX System

引用

WIRELESS PERSONAL COMMUNICATIONS 2013年第4期68卷 1871-1881页

作者： Mohades, Zohreh Vakili, Vahid Tabataba Razavizadeh, S. Mohammad Abbasi-Moghadam, Dariush IUST Sch Elect Engn Dept Telecommun Tehran Iran IUST Dept Elect Engn Tehran Iran Shahid Bahonar Univ Dept Elect Engn Kerman Iran

In this paper;dynamical resource allocation scheme is proposed to improve throughput and fairness in the modern broadband wireless systems such as IEEE 802.16 Worldwide Interoperability for Microwave Access. To assign the subcarriers to users, dynamic fractional frequency reuse is used. In dynamic fractional frequency reuse, each cell is partitioned into two regions, one called super region and another called regular region. Regular region is divided into 3 parts which correspond to the three sectors. In this method, a utility function is firstly used for the subcarrier allocation to the geographical regions and then opportunistic scheduling is applied for the assignment subcarriers to users in each cell. In order to increase the throughput of the system, adaptive modulation and coding techniques are used. Using dynamic fractional frequency reuse reduces fairness among users of a cell. Therefore a random access sub-band is applied to improve the fairness of the system.

关键词： Dynamic fractional frequency reuse WiMAX Inter cell interference adaptive modulation and coding Random access

来源：评论

学校读者我要写书评

暂无评论

Physical-Layer adaptive Resource Allocation in Software-Defined Data Center Networks

引用

JOURNAL OF OPTICAL COMMUNICATIONS AND NETWORKING 2018年第12期10卷 1015-1026页

作者： Yang, Mingwei Rastegarfar, Houman Djordjevic, Ivan B. Univ Arizona Dept Elect & Comp Engn Tucson AZ 85721 USA Univ Arizona Coll Opt Sci Tucson AZ 85721 USA

With the deep physical-layer programmability enabled by software-defined networking (SDN), it is now feasible to realize optical data center transceivers that adapt their transmission parameters in response to time-varying traffic demand and signal quality conditions. In this paper, we develop a cross-layer performance tuning framework for wavelength-tunable data center transceivers, combining scalable and secure modulation order and code rate adaptation. We develop new physical-layer control modules and combine SDN control with distributed preamble encoding in order to achieve both rate adaptation and node synchronization in a wavelength-routing data center testbed. Our experimental and theoretical studies based on pulse amplitude modulation and low-density parity-check coding point to the significance of joint modulation order and code-rate adaptation in data centers. We report real-time resource adaptation with switching speeds on the order of hundreds of milliseconds.

关键词： adaptive modulation and coding Data center Preamble encoding Pulse amplitude modulation (PAM) Software-defined networking (SDN) Wavelength routing

来源：评论

学校读者我要写书评

暂无评论

adaptive scheduling for MIMO wireless networks:: Cross-layer approach and application to HSDPA

引用

IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2007年第1期6卷 259-268页

作者： Aniba, Ghassane Aissa, Sonia EMT INRS Montreal PQ H5A 1K6 Canada

In this paper, we consider the scheduling problem in multiple-input multiple-output (MIMO) wireless networks. The main important characteristic of an optimal scheduler is to maximize throughput while servicing users in a fair manner. Herein, we formulate MIMO scheduling as a Generalized Assignment Problem (GAP) and propose a general solution for the GAP, namely, a Cross-Layer MIMO scheduler (CMS), which uses a novel adaptive Proportional Fairness (APF) mapping approach in conjunction with a new Fast Transmit Antenna Selection (FTAS) technique, to determine the set of users to transmit to and the antenna over which the data associated to each user should be transmitted. The proposed scheduler is applied for packet transmission in High-Speed Downlink Packet Access (HSDPA), taking advantage of the use of adaptive modulation and coding while coping with the constraints on the maximum number of simultaneous codes a user equipment can support, the limited uplink signalling, and the absence of fast power control. Numerical results show that the proposed CMS provides up to 70% increase in total throughput compared to other scheduling schemes.

关键词： adaptive modulation and coding antenna selection cross-layer design HSDPA MIMO systems scheduling

来源：评论

学校读者我要写书评

暂无评论

Resource management to increase connection capacity of real-time streaming in mobile WiMAX

引用

IET COMMUNICATIONS 2010年第9期4卷 1108-1115页

作者： Tsai, M. -H. Sung, J. -T. Huang, Y. -M. Natl Cheng Kung Univ Dept Engn Sci Tainan 70101 Taiwan

With large network coverage, high transmission rate, strong quality of service (QoS) assurance and inexpensive deployment cost, mobile WiMAX has emerged as one of the most promising broadband wireless access technologies. However, resource management is still a challenging issue between system capacity and user gratification, especially for multimedia transmission which ordinarily requires strict delay constraints. In this study, the authors propose an adaptive call admission control in order to efficiently increase system capacity. The control mechanism can admit an incoming video on demand (VOD) connection establishing even without sufficient idle slots/bandwidth to meet the QoS requirement. With consideration of the existing VOD user stream buffer (USB), our scheduling mechanism performs adaptive admission control and QoS provision feasible each time. Also employing adaptive modulation and coding (AMC) scheme, each connection keep its fluency of real-time video performance over dynamic wireless channel status. The authors evaluate the concurrent stream connection number and connection blocking probability with different resource management strategies.

关键词： Image and video coding connection capacity real-time streaming adaptive call admission control video on demand mobile WiMAX multimedia transmission video streaming quality of service broadband networks Mobile radio systems video coding mobility management (mobile radio) WiMax Network management high transmission rate resource management broadband wireless access technologies adaptive modulation and coding QoS assurance

来源：评论

学校读者我要写书评

暂无评论

Novel resource allocation algorithms for multiuser downlink MIMO-OFDMA of FuTURE B3G systems

引用

Progress in Natural Science:Materials International 2009年第9期19卷 1141-1146页

作者： Qiaoyun Sun, Hui Tian *, Shuang Wang, Kun Dong, Ping Zhang Key Laboratory of Universal Wireless Communication, Ministry of Education, Wireless Technology Innovation Institute, Beijing University of Posts & Telecommunications, Beijing 100876, China [a]Key Laboratory of Universal Wireless Communication Ministry of Education Wireless Technology Innovation Institute Beijing University of Posts & Telecommunications Beijing 100876 China

In this paper, subcarrier and power allocation problems for multiuser downlink MIMO-OFDMA of the FuTURE B3G TDD system are investigated. For the reciprocity of the TDD channel, the channel state information can be employed at the transmitter, thus eigen beamforming can be implemented efficiently. With the goal of minimizing the total transmit power under the condition that the QoS requirement of each user can be guaranteed, a novel dynamic resource allocation scheme is proposed to exploit the multiuser diversity gain. The proposed algorithm involves adaptive subcarrier allocation, adaptive modulation and eigen beamforming and achieves significant improvement in overall system performance. Based on the proposed scheme, a modified bit and power allocation is developed. The modified scheme reduces the computational complexity at little expense of system performance. Numerical simulations show that the proposed algorithm and the modified scheme can decrease the total transmit power effectively.

关键词： adaptive modulation and coding Dynamic resource allocation Eigen beamforming MIMO–OFDMA

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：