检索结果-内蒙古大学图书馆

IEEE International Symposium on Information Theory

作者： B. Ryabko J. Astola Siberian State University of Telecommunications and Computer Science Novosibirsk Russia Tampere International Center for Signal Processing the Technical University of Tampere Finland

In this paper we suggest a method of grouping for speeding up codes depending on the alphabet size. The method of grouping is applied to the set of all possible blocks in such a way to reduce redundancy and the comput... 详细信息

关键词： Encoding Signal processing algorithms Application software Signal processing Probability distribution Telecommunication computing Electronic mail Computational efficiency Data compression adaptive coding

来源：评论

学校读者我要写书评

暂无评论

Fairness enhancement of link adaptation techniques in wireless access networks

Fairness enhancement of link adaptation techniques in wirele...

引用

IEEE Conference on Vehicular Technology (VTC)

作者： M.H. Ahmed H. Yanikomeroglu S. Mahmoud Department of Electrical & Computer Engineering Memorial University of Newfoundland Saint John's Canada Broadband Commun. & Wireless Systems (BCWS) Centre Department of Systems & Computer Engineering Carleton University Ottawa Canada

Link adaptation techniques, such as power control and adaptive coding and modulation, aim at maximizing the throughput in wireless networks while maintaining the signal quality in terms of the signal to interference ratio. However, fair resource allocation among different users must be taken into consideration, particularly in fixed broadband wireless access networks. The low/no mobility of users in such networks can lead to location-dependent resource utilization, which causes a significant variation in the performance from a user to another. For instance, adaptive coding and modulation schemes increase the aggregate throughput in the network; however, they also increase the variation of the throughput among users. In this paper, we propose, and analyze the performance of, three fairness enhancement schemes that can be integrated with link adaptation techniques. Results show that the three proposed scheme can enhance the fairness of link adaptation techniques with different degrees without causing (or with minor) degradation to the total network throughput.

关键词： Wireless networks Throughput adaptive coding Modulation coding Resource management Power control Interference Aggregates Performance analysis Degradation

来源：评论

学校读者我要写书评

暂无评论

adaptive code rate for orthogonal code hopping multiplexing (OCHM) in synchronous downlink

Adaptive code rate for orthogonal code hopping multiplexing ...

引用

IEEE Conference on Wireless Communications and Networking

作者： Jae Kyun Kwon Suwon Park Dan Keun Sung Heesoo Lee Department of EECS Korea Advanced Institute of Science and Technology Daejeon South Korea Telecommunications Research and Development Center Samsung Electronics Company Limited Suwon Gyeonggi South Korea Mobile Telecommunication Research Laboratory Electronics and Telecommunications Research Institute Daejeon South Korea

We proposed an Orthogonal Code Hopping Multiplexing (OCHM) scheme as a new statistical multiplexing scheme in synchronous downlink. OCHM enables a large number of users to share a limited number of code channels through statistical multiplexing. In this paper, we obtain the optimal code rate in several traffic load environments by simulation and summarize the appropriate traffic load region for each code rate as the optimal code rate. An adaptive code rate control scheme is proposed and the base station adaptively changes the code rate according to traffic environments in order to save power.

关键词： adaptive coding Downlink OFDM Telecommunication traffic Information rates Degradation Code division multiplexing Error analysis Collision mitigation Automatic control

来源：评论

学校读者我要写书评

暂无评论

Optimizing TCP performance with hybrid ARQ and scheduler

Optimizing TCP performance with hybrid ARQ and scheduler

引用

IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC)

作者： Haitao Zheng H. Viswanathan Wireless Technology Research Bell-Laboratories Lucent Technologies Inc. Holmdel NJ USA

Third generation wireless systems typically employ adaptive coding and modulation, scheduling, and hybrid automatic repeat request (HARQ) techniques to provide high speed packet data service on the downlink. One important consideration in designing such a system is algorithm for the selection of coding and modulation schemes based on the channel quality of the link. We propose a systematic approach to optimize the mapping between signal-to-interference-and-noise ratio (SIlSR) and modulation and coding scheme (MCS) to maximize the throughput that takes into account the type of HARQ scheme employed. Extensive simulation results comparing performance of the proposed methods to conventional methods are presented.

关键词： Automatic repeat request Throughput Downlink Modulation coding Multiaccess communication Feedback Error analysis Hybrid power systems adaptive coding Algorithm design and analysis

来源：评论

学校读者我要写书评

暂无评论

adaptive coding protection and power control in CDMA wireless networks

Adaptive coding protection and power control in CDMA wireles...

引用

IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC)

作者： A. Abrardo G. Benelli G. Giambene D. Sennati Dipartimento di Ingegneria dell'Informazione Università degli Studi di Siena Siena Italy

This paper envisages data transmissions in a low-mobility wireless local area network based on a DS-CDMA air interface. A Rayleigh fading channel and suitable Internet-like traffic model have been envisaged to study the impact of the closed-loop power control on an adaptive coding scheme. The following quality of service (QoS) parameters have been considered in this study: the mean datagram transmission delay and the mean transmission energy per useful bit. We have obtained that our proposed adaptive coding scheme permits one to avoid the use of closed-loop fast power control. Such choice permits one to improve both previous QoS parameters, so allowing an efficient management of radio resources.

关键词： adaptive coding Protection Power control Multiaccess communication Quality of service Data communication Wireless LAN Fading Internet Communication system traffic control

来源：评论

学校读者我要写书评

暂无评论

Neuro-fuzzy networks in adaptive coding of telecommunications channels

Neuro-fuzzy networks in adaptive coding of telecommunication...

引用

Conference of the North American Fuzzy Information Processing Society - NAFIPS

作者： S. Zahan Communications Department Technical University of Cluj Napoca Cluj-Napoca Romania

Within the paper a system that controls the adaptive coding scheme of time varying telecommunications channels is presented. It is implemented by Berenji's neuro-fuzzy network GARIC (Generalized Approximate Reasoning-Based intelligent Control). A major advantage of this approach is that the system does not rely on any specific model of the channel. Another important advantage is that the system is able to adapt itself both to short and long term changes of the channel characteristics. A large part of the paper is devoted to the experimental work. An important conclusion is that, due to its adaptation capability, the system proves a large degree of flexibility and, in the same time, performances comparable or even better than the ones obtained using systems that "know" the model of the channel they are working on.

关键词： Fuzzy neural networks Intelligent networks adaptive coding Communication channels Channel coding Control systems Programmable control adaptive control Fuzzy systems Forward error correction

来源：评论

学校读者我要写书评

暂无评论

A data link control protocol for wireless ATM networks with adaptive coding rate

A data link control protocol for wireless ATM networks with ...

引用

IEEE Workshop on High Performance Switching and Routing

作者： K.S. Chan S. Chan K.T. Ko Department of Electronic Engineering City University of Hong Kong Kowloon Hong Kong China

We propose a new data link control protocol for wireless ATM networks. This new protocol can support both real time and non-real-time services by adopting different error control mechanisms. For real-time traffic, only forward error control (FEC) is used for error correction. For non-real-time traffic, a hybrid automatic repeat request (ARQ) scheme is adopted to reduce the cell loss ratio to a minimum level. In both the FEC and hybrid ARQ schemes, the coding rate is adapted to the channel conditions. When the signal-to-noise ratio (SNR) is high, the coding rate may be higher; while when the channel is bad, the coding rate is adjusted to be lower. The automatic coding rate adaptiveness guarantees the high utilization of the scarce wireless channel resources.

关键词： Wireless application protocol adaptive coding Error correction Forward error correction Automatic repeat request Delay Bandwidth Bit rate Radio link Cyclic redundancy check

来源：评论

学校读者我要写书评

暂无评论

On asymptotically optimal methods of prediction and adaptive coding for Markov sources with unknown memory

On asymptotically optimal methods of prediction and adaptive...

引用

IEEE International Symposium on Information Theory

作者： B. Ryabko F. Topsoe Information Science Siberian State University of Telecommunications Novosibirsk Russia Department of Mathematics University of Copenhagen Copenhagen Denmark

The asymptotically optimal methods of prediction for Markov sources with unknown memory are suggested. The methods are based on modified twice universal scheme.

关键词： adaptive coding Statistics Probability Telecommunications Mathematics Information theory Prediction methods Size measurement Time measurement

来源：评论

学校读者我要写书评

暂无评论

Multilayered image representation: Application to image compression

引用

IEEE TRANSACTIONS ON IMAGE PROCESSING 2002年第9期11卷 1072-1080页

作者： Meyer, FG Averbuch, AZ Coifman, RR Univ Colorado Dept Elect Engn Boulder CO 80309 USA Tel Aviv Univ Sch Math Sci Dept Comp Sci IL-69978 Tel Aviv Israel Yale Univ Dept Math New Haven CT 06510 USA

The main contribution of this work is a new paradigm for image representation and image compression. We describe a new multilayered representation technique for images. An image is parsed into a superposition of coherent layers: piecewise smooth regions layer, textures layer, etc. The multilayered decomposition algorithm consists in a cascade of compressions applied successively to the image itself and to the residuals that resulted from the previous compressions. During each iteration of the algorithm, we code the residual part in a lossy way: we only retain the most significant structures of the residual part, which results in a sparse representation. Each layer is encoded independently with a different transform, or basis, at a different bitrate, and the combination of the compressed layers can always be reconstructed in a meaningful way. The strength of the multilayer approach comes from the fact that different sets of basis functions complement each others: some of the basis functions will give reasonable account of the large trend of the data, while others will catch the local transients, or the oscillatory patterns. This multilayered representation has a lot of beautiful applications in image understanding, and image and video coding. We have implemented the algorithm and we have studied its capabilities.

关键词： adaptive coding cosine transforms image coding multilayered coding wavelet transforms

来源：评论

学校读者我要写书评

暂无评论

Performance analysis of variable rate: Symbol-by-symbol adaptive bit interleaved coded modulation for Rayleigh fading channels

引用

IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2002年第3期51卷 537-550页

作者： Lau, VKN Bell Labs Whippany NJ 07981 USA

A challenging problem in offering high-speed data service over wireless is to protect data over the error-proned fading channel in an effective way (high-bandwidth efficiency). In this paper, we propose a bandwidth-efficient error correction scheme, namely the variable rate adaptive bit interleaved coded modulation (ABICM), for the wireless mobile channel. The code rate and modulation level are varied according to the current channel state to exploit the time-varying nature of the wireless channel. Design challenges to achieve symbol-by-symbol adaptation are addressed. In particular, we address the criteria to choose the family of component codes for the ABICM system. We propose a multilevel puncturing scheme that solves the problem of symbol-by-symbol adaptive puncturing and interleaving. Equivalent distance spectrum for variable rate symbol-by-symbol adaptive codes are introduced and analytical bounds on adaptive codes are derived that enable us to determine the optimal adaptation thresholds. Two operation modes, namely the constant throughput and the constant bit error rate (BER) controls, are proposed. It is found that there are significant gains relative to fixed-rate coding in terms of signal-to-noise ratio (SNR) and throughput. It is also found that the ABICM scheme is essentially not degraded when used with small interleaving depths. This makes the ABICM very suitable for real-time applications.

关键词： adaptive bit interleaved coded modulation (ABICM) adaptive coding bit interleaved modulation

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：