共查询到18条相似文献,搜索用时 109 毫秒
1.
为了解决无线通信系统中多输入多输出技术在移动终端的多天线制约问题,一种新的分集技术-协作分集技术被提出。编码协作分集可以在慢衰落环境下取得较好的性能,但在快衰落环境下性能较差,文中对编码协作分集进行了延伸,考虑了在快衰落环境下的空时编码协作分集和自适应空时编码协作分集。 相似文献
2.
协作MIMO通过多个单天线节点的相互协作构造多发射天线,以此形成一种虚拟MIMO多天线阵列获得空间分集增益。考虑到协作MIMO特点,天线间采用分布式空时编码进行编码协作。文章研究了协作MIMO中基于分布式空时码(DSTC)的分集复用折衷(DMT)新方案,该方案通过推导两种DSTC的中断概率与分集增益表达式,结合两类DSTC的DMT策略,根据改变复用增益阈值自适应获得最佳DMT与中断性能。数值仿真表明,所提的DMT策略可以逼近协作MIMO的DMT上限,协作节点采用该策略的中断性能仅次于上限的中断性能。在多节点构成协作MIMO网络分布式空时编码协作中,提出的DMT新方案可使系统高效地获得协作分集增益与中断性能。 相似文献
3.
4.
5.
协作发射分集系统及其误码性能分析 总被引:3,自引:0,他引:3
协作分集(cooperative diversity)技术通过使网络中各单天线用户共享彼此天线,形成虚拟的多天线阵列来实现发射或接收分集,并结合一定的编码方式,可以有效地提高系统性能。多载波码分多址(MC-CDMA,multi.carder code division multiple access)技术将数据调制到各个子载波上发送,可以有效地抵抗信道频率选择性衰落的影响。由此提出了无线网络中频率选择性衰落信道环境下的一种基于分布式空时分组码(DSTBC,distributed space tim eblock code)和MC-CDMA的协作发射分集方案,建立了协作用户间的误码表示模型,基于该模型推导了在协作条件下整个系统误码性能的理论表达式。分析了协作用户间的平均解码差错概率对系统误码性能的影响,并给出了仿真结果。结果表明,本系统相对于未编码的MC-CDMA系统获得了明显的性能增益,同时仿真也较好地验证了理论结果。 相似文献
6.
协作分集技术是一种新型的空间分集技术,它通过使多个具有单天线的终端共享彼此的天线,达到获得多天线分集增益的目的。协作分集技术能够提高系统的容量,降低系统的误码率。本文主要介绍了协作分集的概念分类,以及在多用户协作条件下的系统模型。 相似文献
7.
利用单天线终端相互协作,形成虚拟多天线发射阵列,结合接收端基站多天线接收,以此实现协作MIMO系统,同时将MIMO中的空时编码理论应用其中,可以有效利用空间分集增益和编码增益,抵抗多径衰落并提高系统性能。其中,由于分布式空时分组码(D-STBC)能有效地利用空间分集,且编码简单、性能优越,因而重点研究其在协作MIMO中的运用,对其进行了建模,设计了D-STBC接收端检测器结构,指出极大似然(ML)检测的复杂度随协作节点数的增加呈指数增长,并推导了在ML检测下的系统成对差错概率(PEP)性能;同时介绍了基于空间复用的分布式垂直型贝尔实验室分层空时编码(D-VBLAST),它可以有效地提高数据传输速率(吞吐量),且译码算法复杂度可以随着数据速率的增加线性升高,适合于相对较高SNR的协作MIMO传输系统。 相似文献
8.
协作分集技术是一种新型的空间分集技术,它通过使多个具有单天线的终端共享彼此的天线,达到获得多天线分集增益的目的.协作分集技术能够提高系统的容量,降低系统的误码率.本文主要介绍了协作分集的概念分类,以及在多用户协作条件下的系统模型. 相似文献
9.
10.
11.
This article proposes a new space-time cooperative diversity scheme called full feedback-based cooperative diversity scheme (FFBCD). In contrast to the conventional adaptive space-time cooperative diversity schemes that utilize the feedback from only the destination node, the new scheme utilizes the feedback from both the destination node and the cooperation node. With the feedback from the destination node, the occasional successful reception of the destination node in the information distribution stage can be detected, thus avoiding unnecessary retransmissions in the information delivery stage. The feedback from the cooperation node indicates the receiving state of the cooperation node in the information distribution stage, and the source node and the cooperation node will not perform cooperative retransmission during the information delivery stage unless the cooperation node is received successfully in the information distribution stage. In this way the new scheme can reduce the number of transmission attempt and improve the channel utilization. The expressions of the average number of transmission attempt are given. Numerical approximations and simulation results both show that the new scheme performs better than the non-cooperative scheme and the conventional adaptive space-time cooperative diversity scheme. 相似文献
12.
Cooperative space-time coding for wireless networks 总被引:1,自引:0,他引:1
We consider a cooperative transmission scheme in which the collaborating nodes may have multiple antennas. We present the performance analysis and design of space-time codes that are capable of achieving the full diversity provided by user cooperation. Our codes use the principle of overlays in time and space, and ensure that cooperation takes place as often as possible. We show how cooperation among nodes with different numbers of antennas can be accomplished, and how the quality of the interuser link affects the cooperative performance. We illustrate that space-time cooperation can greatly reduce the error rates of all the nodes involved, even for poor interuser channel quality. 相似文献
13.
14.
Coded cooperation in wireless communications: space-time transmission and iterative decoding 总被引:14,自引:0,他引:14
Janani M. Hedayat A. Hunter T.E. Nosratinia A. 《Signal Processing, IEEE Transactions on》2004,52(2):362-371
When mobiles cannot support multiple antennas due to size or other constraints, conventional space-time coding cannot be used to provide uplink transmit diversity. To address this limitation, the concept of cooperation diversity has been introduced, where mobiles achieve uplink transmit diversity by relaying each other's messages. A particularly powerful variation of this principle is coded cooperation. Instead of a simple repetition relay, coded cooperation partitions the codewords of each mobile and transmits portions of each codeword through independent fading channels. This paper presents two extensions to the coded cooperation framework. First, we increase the diversity of coded cooperation in the fast-fading scenario via ideas borrowed from space-time codes. We calculate bounds for the bit- and block-error rates to demonstrate the resulting gains. Second, since cooperative coding contains two code components, it is natural to apply turbo codes to this framework. We investigate the application of turbo codes in coded cooperation and demonstrate the resulting gains via error bounds and simulations. 相似文献
15.
限定时空条件下,射频综合系统有效发挥多功能效应的实质是实现系统多功能协同高效运行,而制约其协同高效运行的瓶颈是特定时空条件下可用的电磁资源。电磁资源的高效利用依赖电磁协同,是按照任务要求及限定条件,在时间、频率、空间、能量多个维度寻求构建电磁协同自组织结构的最优解,并确定具体任务时空下有序运行自组织结构的驱动方式,按照求解出的电磁资源动态分配结果,执行任务,使系统电磁效应在任务牵引下受控。电磁协同服务于多功能射频综合系统融合,可以有效利用、管理战场电磁环境,高效提升多功能射频综合系统的运行效率。本文从多功能射频综合系统融合运行之瓶颈、电磁协同概念和电磁协同方法三个方面论述电磁协同的核心要点,期望为实现多功能射频综合系统融合运行提供可行的技术途径。 相似文献
16.
To design a scheme that can approaching the capacity 1imitation transfer,and genera11y app1ied to s1ow and fast fading,the coded cooperation based on LDPC convo1utiona1 codes was studied.First1y,based on LDPC convo1utiona1 codes,the coded words were divided into two parts by puncturing a1gorithm to achieve coded cooperation.The space-time transmission was introduced into the second frame of coded cooperation to further improve the performance of the system.Simu1ation resu1ts show the effectiveness of proposed scheme. 相似文献
17.
Adaptive network coded cooperation (ANCC) for wireless relay networks: matching code-on-graph with network-on-graph 总被引:1,自引:0,他引:1
Xingkai Bao Jing Li 《Wireless Communications, IEEE Transactions on》2008,7(2):574-583
We consider user cooperation in a relay network that comprises a large collection of transmitters sending wireless data to a common receiver. A new framework exploiting the network coding technology, referred to as adaptive network coded cooperation (ANCC), is proposed to combat the lossy nature of wireless links and to adapt to the changing network topology. The central idea is to match network-on-graph, i.e. instantaneous network topologies described in graphs, with the well-known class of code-on-graph, i.e. low-density parity-check (LDPC) codes and LDPC-like codes. Both achievable rates and outage probabilities are evaluated for ANCC, and closed-form expressions are derived for the asymptotic case where the network size increases without bound. Compared with the existing schemes, ANCC significantly outperforms repetition-based schemes and performs on par with space-time coded cooperation (STCC), but obviates the need for stringent inter-user synchronization at the bit/baud level. 相似文献
18.
针对无线ad hoc网络中协作造成的中继效率低以及不同QoS需求难以满足等问题,提出了一种联合网络编码和空时编码的协作MAC协议(NSTCMAC)。NSTCMAC将网络编码与空时编码技术相结合,设计出区分业务类型的协作MAC协议传输机制,以满足不同业务类型的QoS需求;进一步通过马尔科夫链模型分析了区分业务类型的协作机制及性能。仿真结果表明,相比传统的DCF、COOPMAC以及CD-MAC协议,NSTCMAC协议能更好地保证不同的QoS需求,并能有效地解决协作造成的中继效率低的问题。 相似文献