共查询到19条相似文献,搜索用时 125 毫秒
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一种基于MCS信息的白适应MIMO机制选择算法 总被引:1,自引:1,他引:0
文章讨论了在时变无线信道下多天线无线通信系统中MIMO机制的选择问题,并提出一种基于调制编码(Modulationand Coding Scheme,MCS)信息的MIMO机制选择方案。该方案通过对MCS信息进行统计和分析,自适应的选择MIMO机制以获得最大吞吐量。与已有MIMO选择方案相比,该算法不仅仍能准确地选择出合适的MIMO机制,而且易于实现,更容易应用于实际系统中。 相似文献
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本文提出了一种通用的自适应编码调制系统吞吐量性能分析方法.基于各固定编码调制方式的误码率(BER)性能,使每种编码调制方案对应于一个信道平均信噪比(SNR)范围,再应用拉格朗日函数法得到使自适应编码调制系统吞吐量性能最大的信噪比转换门限,可得到系统的平均吞吐量性能.数值分析结果表明,相对于自适应M进制正交幅度调制(MQAM),自适应Turbo编码MQAM系统吞吐量性能有显著提高,并且该性能受瞬时误码率要求的影响较小.Nakagami信道中,在相同平均信道信噪比条件下,随着m的增大,系统吞吐量性能提高缓慢. 相似文献
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本文介绍了第四代移动通信(4G)系统中的OFDM和MIMO技术,叙述了MIMO—OFDM系统模型及其相应的关键技术,包括同步技术、空时处理技术、自适应调制和编码技术、信道估计技术。 相似文献
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可见光多输入多输出(MIMO)通信中空时分组编码能够获得较高的分集增益,但是其有效性较差,空间调制编码能够提高系统的频谱利用率但其可靠性较差。因此结合空时分组编码和空间调制编码的优势设计出空时分组-空间调制(STBC-SM)级联编码应用到可见光MIMO通信系统中,根据朗伯光源衰减特性建立了可见光室内传输信道模型,并对系统有效性及可靠性进行了仿真验证。结果表明在确保原有效性和相同误码率前提下,STBC-SM级联编码的可靠性较SM提高了5~8 dB,在确保原可靠性的前提下,STBC-SM级联编码的有效性较STBC提高了。表明文中设计的级联编码可有效的解决通信系统中有效性与可靠性的矛盾问题,为研究室内可见光MIMO通信提供了很好的理论意义。 相似文献
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本文讨论了MIMOOFDM系统中一种基于自适应编码调制的的跨层传输技术。该技术结合传统物理层自适应编码调制和数据链路层自动请求重发,利用信道估计参数和数据链路层的误包率计算自适应编码调制门限,在系统给定时延和误包率约束的基础上最大程度地提高频谱利用率。仿真结果表明,编码系统具有很强的差错控制作用,相比传统物理层自适应编码调制系统和未编码系统都提高了频率利用率;当频率利用率为1时,相比于未编码系统,编码带来的增益为4dB。同时这种强差错控制作用也使得改变系统最大重传次数对切换门限的影响变小,因此跨层自适应编码调制相比传统物理层自适应带来的频谱效率的提高变小,这就使得实际系统能以较小的时延代价换取足够的频谱利用率增益。 相似文献
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Multiple-input multiple-output (MIMO) technology can provide high data rate and substantial diversity. Space time block code (STBC) provides diversity gain and obtains signal of better quality even under bad channel conditions. However, it has no contribution to system average throughput. Vertical-bell laboratory layered space-time (VBLAST) improves peak data rate but leads to higher packet error rate (PER) at cell edge when the channel condition is poor. To get both higher system average throughput and cell edge throughput, an adaptive STBC-VBLAST transmission for downlink mobile WiMAX system is proposed and analyzed through system-level simulation in this article. The proposed approach compares the effective capacity of two candidate MIMO modes (STBC or VBLAST) and reports its decision to the base station with only one extra signaling bit. The simulation results show that the proposed approach can attain a balance between STBC and VBLAST. Besides, the cell throughput approximates that of pure VBLAST and the cell edge throughput is close to that of pure STBC. 相似文献
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A cross layer approach based on queuing and adaptive modulation for MIMO systems has been presented. To realize the system, an adaptive modulation scheme using MIMO systems combined with finite-length queuing at the data link layer has been designed. A finite state Markov chain for MIMO channels has been constructed to persue the queuing analysis. The packet loss rate, the average throughput, and the average spectral efficiency have been computed. Furthermore, the packet error rate for adaptive modulation to minimize the packet loss rate and maximize the average throughput is extracted. The obtained results present the advantages of using the proposed cross layer architecture. 相似文献
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Bing Hui Manar Mohaisen Dongkeol Han KyungHi Chang YoungSeok Baek Bontae Koo 《Wireless Personal Communications》2012,67(3):505-523
In this paper, two novel multiple-input multiple-output (MIMO) detection algorithms, adaptive parallel QRDM (APQRDM) and adaptive iterative QRDM (AIQRDM) which are able to achieve the similar detection throughput as conventional QRDM while reducing the computational complexity, are introduced, and the system performances are evaluated on the platform of 3GPP LTE downlink. In both 2 ×?2 and 4 ×?4 MIMO, APQRDM and AIQRDM algorithms can achieve almost same packet error rate performance as those of conventional QRDM algorithm, while the computational complexity is significantly reduced. Also, the receiver employing APQRDM and AIQRDM detection algorithms shows the almost same throughput as the case of conventional MIMO detection algorithms. Furthermore, practical channel estimation techniques are employed, and the system performances are thoroughly analyzed and discussed. 相似文献
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《Journal of Visual Communication and Image Representation》2008,19(8):520-528
In this paper, we present a novel scalable video transmission strategy over multi-input multi-output (MIMO) wireless systems with time-varying channel capacity. It is a great challenge to simultaneously guarantee the QoS for video delivery and maximize the system throughput over time-varying MIMO channel. We demonstrate that, by making full use of estimated channel state information (CSI) through feedback, a cascade of adaptive operations can be designed to satisfy maximum throughput for scalable video over MIMO systems. These operations include power allocation based on water-filling (WF), adaptive channel selection (ACS), and novel throughput maximizing power reallocation (PR). The proposed ACS transmission scheme enables overall increase in data throughput among enhancement layers by adaptively launching base layer bit-stream to proper sub-channel. Then, after initial power allocation with WF and proper adaptive mode selection, we obtain the surplus power across enhancement layer sub-channels which can be reallocated to some sub-channels by the proposed PR scheme. With such power reallocation, certain enhancement layers will be able to reach new level of QAM modulation through PR so as to maximize the system data throughput. We present in this paper some detailed analysis on these adaptive operations. We also present some simulation results to demonstrate that maximum throughput video transmission over MIMO wireless systems indeed can be achieved based on scalable video coding (SVC) and a sequence of appropriately designed adaptive operations. 相似文献
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In this paper, we study a multi-mode quantized precoding multiple-input multiple-output (MIMO) system with per-substream adaptive modulation and coding under a maximal throughput target. An analytical throughput expression is firstly presented by recurring to Gaussian mixed approximation for block error rate of Turbo codes. An optimal mode-MCS (modulation and coding scheme) selection algorithm is then developed to achieve maximal throughput performance based on throughput criterion. Further, a complexity-reducing selection algorithm with negligible performance loss is proposed by making full use of the information provided by singular value decomposition of the instantaneous channel matrix at the receiver side. Simulation results show that both selection algorithms can achieve good throughput performance in the above mentioned MIMO system. 相似文献
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Future high speed mobile applications require diverse Quality of Service (QoS). To provide flexible data rate services while
satisfying the low delay requirements, adaptive MIMO OFDM is a promising technique over time varying channels. In this paper
a variable power adaptive MIMO OFDM system under imperfect CSI using cross layer design for mobile ad hoc networks is proposed.
Data throughput is maximized while maintaining the delay QoS requirements in the presence of channel estimation errors. Numerical
results show that the variable power adaptive MIMO OFDM system provides better spectral efficiency than its constant power
counterpart. 相似文献
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缓存辅助多天线中继技术可以为5G通信系统提供广域覆盖范围,并且有效改善系统的吞吐率性能.研究了一个三节点多天线缓存辅助中继系统,提出了最大化系统平均吞吐率的最佳缓存辅助中继策略,即联合自适应链路选择以及功率分配方案.分析结果表明,最佳的链路选择方案仅依赖于当前的瞬时信道状态信息以及相关链路的信道统计信息,而最佳功率分配方案是对发送的数据流进行等功率分配.仿真结果表明,相对于无缓存辅助的MIMO中继系统,缓存的引入能够显著改善中继系统的吞吐率.此外,MIMO技术的引入还能够获得多天线所带来的复用增益,进一步改善缓存辅助中继系统的吞吐率. 相似文献
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Implementation of a MIMO OFDM-based wireless LAN system 总被引:11,自引:0,他引:11
The combination of multiple-input multiple-output (MIMO) signal processing with orthogonal frequency division multiplexing (OFDM) is regarded as a promising solution for enhancing the data rates of next-generation wireless communication systems operating in frequency-selective fading environments. To realize this extension of OFDM with MIMO, a number of changes are required in the baseband signal processing. An overview is given of the necessary changes, including time and frequency synchronization, channel estimation, synchronization tracking, and MIMO detection. As a test case, the OFDM-based wireless local area network (WLAN) standard IEEE 802.11a is considered, but the results are applicable more generally. The complete MIMO OFDM processing is implemented in a system with three transmit and three receive antennas, and its performance is evaluated with both simulations and experimental test results. Results from measurements with this MIMO OFDM system in a typical office environment show, on average, a doubling of the system throughput, compared with a single antenna OFDM system. An average expected tripling of the throughput was most likely not achieved due to coupling between the transmitter and receiver branches. 相似文献
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Mário Marques da Silva Américo Correia Nuno Souto José Seguro Paulo Gomes Rui Dinis 《Wireless Personal Communications》2012,66(4):833-853
A coordinated multi-resolution and multi-point MIMO transmission method for the LTE-Advanced is presented considering the Evolved-Multimedia Broadcast/Multicast Service (E-MBMS). Fixed relays with MIMO and different adaptive frequency reuse schemes are considered in the proposed scheme to improve the E-MBMS spectral efficiency at the cell borders and/or to save transmission power from the base stations and relays. In order to provide additional diversity over Rayleigh multi-path fading channels, a signal space diversity based on Complex Rotation Matrices (CRM) is used, associated to MIMO, as a multi-resolution technique. The decoding of these signals are facilitated with the use of Maximum Likelihood Soft Output (MLSO) criterion, included in the proposed receiver. The link performance of the MIMO system turbo-coded with hierarchical constellations and CRM is analyzed in terms of bit and block error rate (BER/BLER). The corresponding system level coverage and throughput gains are also evaluated associated to the presence or not of fixed relays and measuring the maximum spectral efficiencies at cell borders of single cell point-to-multipoint or single frequency network. The influence of the cell radius in the performance of the previous cellular topologies with coordinated MIMO transmissions is also evaluated. 相似文献