检索结果-内蒙古大学图书馆

IEEE Wireless Communications and Networking Conference

作者： Yoon, Young C. Savas, Alpaslan Chen, Wanshi Ericsson Inc. USA San Diego CA 92121 5012 Wateridge Vista Drive United States Ericsson Inc. United States LGE Mobile Research United States

ISBN: (纸本)9781424402694

This paper considers the application of distributed transmit diversity (TD) to digital broadcast networks. Distributed TD allows spatial encoding across transmit sectors (cell-sites or satellites) each with a single antenna. We focus on Alamouti space-frequency (SF) codes in particular and consider terrestrial systems based on cellular type networks. System coverage results are presented for a 1xEV-DO broadcast network based on a comprehensive evaluation methodology developed in 3GPP2 for system modeling and orthogonal frequency division modulation (OFDM). The results show that distributed transmit diversity can deliver significant coverage gains. For example, given a bandwidth of 1.25 MHz, a data rate of 1.2 Mbps and a minimum bit-error rate (BER) requirement of 0.1%, the broadcast coverage increases from roughly 40% in the absence of distributed TD to 70% with the Alamouti linear combiner and to 82% with a zero-forcing (ZF) spatial equalizer.

关键词： space-time coding space-frequency coding Transmit diversity Broadcast networks OFDM Site Diversity Digital Video Broadcasting (DVB)

来源：评论

学校读者我要写书评

暂无评论

Noncoherent space-frequency coded MIMO-OFDM

引用

IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 2005年第9期23卷 1799-1810页

作者： Borgmann, M Bölcskei, H Swiss Fed Inst Technol Commun Technol Lab CH-8092 Zurich Switzerland

Recently, the use of coherent space-frequency coding in orthogonal frequency-division multiplexing (OFDM)-based frequency-selective multiple-input multiple-output (MIMO) fading channels has been proposed. Acquiring knowledge of the fading coefficients in a MIMO channel is already very challenging in the frequency-flat (fast) fading case. In the frequency-selective case, this task becomes significantly more difficult due to the presence of multiple paths, which results in an increased number of parameters to be estimated. In this paper, we address code design for noncoherent frequency-selective MIMO-OFDM fading links, where neither the transmitter nor the receiver knows the channel. We derive the code design criteria, quantify the maximum achievable diversity gain, and provide explicit constructions of full-diversity (space and frequency) achieving codes along with an analytical and numerical performance assessment. We also demonstrate that unlike in the coherent case, noncoherent space-frequency codes designed to achieve full spatial diversity in the frequency-flat fading case can fail completely to exploit not only frequency diversity but also spatial diversity when used in frequency-selective fading environments. We term such codes "catastrophic".

关键词： diversity frequency-selective fading channels multiple-input multiple-output (MIMO) systems noncoherent communications orthogonal frequency-division multiplexing (OFDM) pairwise error probability (PEP) Rayleigh fading space-frequency coding

来源：评论

学校读者我要写书评

暂无评论

Differential space-frequency modulation via smooth logical channel for broadband wireless communications

引用

IEEE TRANSACTIONS ON COMMUNICATIONS 2005年第12期53卷 2024-2028页

作者： Su, WF Liu, KJR SUNY Buffalo Dept Elect Engn Buffalo NY 14260 USA Univ Maryland Dept Elect & Comp Engn College Pk MD 20742 USA Univ Maryland Syst Res Inst College Pk MD 20742 USA

In this letter, a differential space-frequency modulation (DSFM) scheme is proposed for multiple input multiple-output (MIMO)-orthogonal frequency-division multiplexing (OFDM) systems in broadband wireless communications. we assume that the fading channels keep constant only within each OFDM block, and may change independently from one OFDM block to another. The differential schemes proposed for MIMO-OFDM systems in the literature cannot successfully decode with such a rapidly fading channel, since the successful decoding of the previously existing schemes relies on the assumption that the fading channel keeps constant within a period of several OFDM blocks, and it changes slowly from a period of several OFDM blocks to another. In our proposed DSFM scheme, the transmitted signals are differentially encoded in the frequency domain within each OFDM block. Thus, the differential decoding can be performed over subcarriers within each single OFDM block. Furthermore, if a statistical channel power-delay profile (PDP) is known at the transmitter, we propose to create a smooth logical channel to improve the performance of the DSFM scheme. We obtain the smooth logical channel by sorting the channel frequency responses over subcarriers from a statistical point of view. If the logical channel is not smooth enough, we further consider a pruning process in which we use only the "good" part of the channel and get rid of the "bad" part of the channel. Simulation results show that the proposed DSFM scheme over a smooth logical channel (with pruning, if necessary) performs well for various channel PDPs.

关键词： differential space-time (ST) coding frequency-selective fading channels full diversity multiple-input multiple-output (MIMO)-orthogonal frequency-division multiplexing (OFDM) systems space-frequency coding

来源：评论

学校读者我要写书评

暂无评论

Towards maximum achievable diversity in space, time, and frequency: Performance analysis and code design

引用

IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2005年第4期4卷 1847-1857页

作者： Su, WF Safar, Z Liu, KJR SUNY Buffalo Dept Elect Engn Buffalo NY 14260 USA Nokia Danmark AS Technol Platforms Modern Syst Design Copenhagen Denmark Univ Maryland Dept Elect & Comp Engn College Pk MD 20742 USA Univ Maryland Inst Syst Res College Pk MD 20742 USA

Multiple input multiple output (MIMO) communication systems with orthogonal frequency division multiplexing (OFDM) modulation have a great potential to play an important role in the design of the next-generation broadband wireless communication systems. In this paper, we address the problem of performance analysis and code design for MIMO-OFDM systems when coding is applied over both spatial, temporal, and frequency domains. First, we provide an analytical framework for the performance analysis of MIMO-OFDM systems assuming arbitrary power delay profiles. Our general framework incorporates the space-time and space-frequency (SF) coding approaches as special cases. We also determine the maximum achievable diversity order, which is found to be the product of the number of transmit and receive antennas, the number of,delay paths,. and the rank of the temporal correlation matrix. Then, we propose two code design methods that are guaranteed to achieve the maximum diversity order. The first method is a repetition coding approach using full-diversity SF codes, and the second method is a block coding approach that can guarantee both full symbol rate and full diversity. Simulation results are also presented to support the theoretical analysis.

关键词： broadband wireless communications maximum achievable diversity MIMO-OFDM systems multiple antennas space-frequency coding space-time-frequency coding

来源：评论

学校读者我要写书评

暂无评论

On the performance of recursive space-frequency codes and iterative decoding in wideband OFDM-MIMO systems: simulated and measured results

引用

INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS 2004年第8期17卷 789-810页

作者： Fletcher, PN McNamara, DP Piechocki, RJ Nix, AR Dean, M QinetiQ Ltd Malvern Worcs England Univ Bristol Ctr Commun Res Bristol BS8 1UB Avon England

In this paper, we study the performance of a bandwidth efficient space-frequency turbo encoding scheme over wideband channels. Results are presented for simulated wideband MIMO channels consisting of two transmit antennas and up to two receive antennas. In addition, wideband channel measurements undertaken with practical multi-element antenna structures at both the access point (AP) and mobile terminal (MT) are presented. Analysis is in terms of channel capacity, 10% channel outage capacity and space-frequency iterative decoding for an IEEE802.11a physical layer complaint modem. It is shown when operating with a spectral efficiency of 1.2 bits/s/Hz, the iterative decoded space-time codes comes within approximately 4.7 dB of 10% outage capacity over Rayleigh fading wideband channels with two transmit and two receive antennas. Over measured channels the iterative decoding scheme performs within 7.7 dB 10% of outage capacity. Losses due to channel state information estimation are also investigated. Copyright (C) 2004 John Wiley Sons, Ltd.

关键词： OFDM space-time coding space-frequency coding iterative decoding MIMO channel capacity

来源：评论

学校读者我要写书评

暂无评论

space-frequency coded HIPERLAN/2

引用

IEEE TRANSACTIONS ON CONSUMER ELECTRONICS 2004年第4期50卷 1162-1168页

作者： Esli, C Ozgul, B Delic, H Bogazici Univ Dept Elect & Elect Engn TR-34342 Bebek Istanbul Turkey

This paper attempts to provide an evaluation of High Performance Local Area Network Type 2 (HIPERLAN/2), equipped with space-frequency coded double-antenna transmit diversity. The HIPERLAN/2 physical layer entities are simulated for frequency-selective fading channels for the standard's digital modulation schemes of BPSK, QPSK, 16-QAM and 64-QAM. Protocol data unit (PDU) error rate comparisons of HIPERLAN/2 with and without space frequency coding reveal the potential gains and caveats. The analytical bit error probability calculations confirm that the simulation results are consistent with the theory(1).

关键词： OFDM space-frequency coding transmitter diversity wireless LAN

来源：评论

学校读者我要写书评

暂无评论

Bandwidth efficient OFDM transmitter diversity techniques

引用

EURASIP JOURNAL ON APPLIED SIGNAL PROCESSING 2004年第10期2004卷 1508-1519页

作者： Lee, KF Williams, DB Motorola Labs Multimedia Architecture Lab Schaumburg IL 60196 USA Georgia Inst Technol Sch Elect & Comp Engn Atlanta GA 30332 USA

space-time block-coded orthogonal frequency division multiplexing (OFDM) transmitter diversity techniques have been shown to be efficient means of achieving near-optimal diversity gain in frequency-selective fading channels. However, these known techniques all require a cyclic prefix to be added to the transmitted symbols, resulting in bandwidth expansion. In this paper, iterative space-time and space-frequency block-coded OFDM transmitter diversity techniques are proposed that exploit spatial diversity to improve spectral efficiency by eliminating the need for a cyclic prefix.

关键词： space-time coding space-frequency coding transmitter diversity OFDM channel estimation pilot symbols

来源：评论

学校读者我要写书评

暂无评论

Collision avoidance in space-frequency coded FH-OFDMA

Collision avoidance in space-frequency coded FH-OFDMA

引用

IEEE International Conference on Communications (ICC 2004)

作者： Kurt, T Deliç, H Univ Ottawa Sch Informat Technol & Engn Commun & Signal Proc Lab Ottawa ON K1N 6N5 Canada

ISBN: (纸本)0780385330

A frequency hopping, space-frequency coded clustered orthogonal frequency-division multiple access (OFDMA) system is considered. It is shown analytically that SIT coding reduces the number of collisions in OFDMA with random subcarrier hopping. Expressions for the expected number of symbol loss in a cluster collision are derived. Bit error rate computations via simulations in a frequency-selective fading channel corroborate the theoretical findings.

关键词： frequency-hopping OFDMA clustered OFDM space-frequency coding

来源：评论

学校读者我要写书评

暂无评论

Channel tracking and decoding in space-frequency coded OFDM systems over dispersive channels

Channel tracking and decoding in space-frequency coded OFDM ...

引用

7th International Conference on Signal Processing

作者： Xue, YM Su, GC Beijing Inst Technol Dept Electron Eng Informat Sci Beijing 100081 Peoples R China

ISBN: (纸本)7121002159

This paper proposes a novel decoding scheme for OFDM with multi-antenna systems. which uses space-frequency Block coding (SFBC), over time-frequency selective channels. We employ Kalman filtering for MIMO channel matrix tracking in order to enable SFBC-OFDM decoding with diversity gains. Simulation results confirm that the proposed scheme exhibits robustness to time-frequency selectivity.

关键词： Kalman filtering dispersive channels space-frequency coding OFDM

来源：评论

学校读者我要写书评

暂无评论

A space-time coding scheme with maximum diversity gains over frequency-selective fading channels

A space-time coding scheme with maximum diversity gains over...

引用

14th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications

作者： Chen, SP Yao, TR S Cent Univ Nationalities Dept Elect & Informat Engn Wuhan 430074 Hubei Peoples R China

ISBN: (纸本)7505350668

We introduce a novel space-time coding scheme, called space-time cyclic-delay coding (STCDC), for multiple input multiple output orthogonal frequency-division multiplexing (MIMO-OFDM) systems over frequency-selective fading channels. The scheme exploits the redundancy introduced by channel coding. The transmitter antennas send the cyclically delayed copies of OFDM symbols, and the receiver uses the maximum likelihood estimation method to estimate the transmitted sequence. We show that STCDC-OFDM can achieve the maximum diversity, which is the product of the number of transmitter antennas the number of receiver antennas (N-r) and the channel length (L), if the error control code has at least a free distance of NrL. Compared with the existing space-time coding and space-frequency coded MIMO-OFDM techniques, the proposed scheme has the advantages of being independent from the number of transmit antennas and having a lower implementation complexity.

关键词： cyclic delay coding OFDM diversity space-time coding space-frequency coding

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：