共查询到18条相似文献,搜索用时 234 毫秒
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在基于中继的双向无线通信系统中,分析了两时隙、三时隙和四时隙的中继传输模式的系统和速率性能。考虑到实际通信场景中,信道估计误差的存在使得两时隙和三时隙传输系统的自干扰无法完全消除,研究了信道估计误差对系统和速率性能的影响。仿真结果表明,在公平的发送总功率和信息交换的前提下,两时隙和三时隙传输的和速率在无信道估计误差时在任何信噪比情况下均优于四时隙传输,随着信道估计误差的增加,其和速率显著下降。 相似文献
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该文在双向多中继选择系统中,分析了采用自适应调制的基于三时隙时分广播(TDBC)中继传输协议的系统性能,给出了存在信道估计误差时,系统的端到端信干噪比表达式,然后通过不等式缩放将表达式转化为多个服从指数分布变量和的形式,求出了其上界的分布,并利用该分布推导出了系统平均频谱效率的上界闭式表达式。通过仿真可以看出,理论分析结果与蒙特卡洛仿真结果相吻合,随着信道估计误差的增加,系统的平均频谱效率降低,并会由于自干扰不能完全被消除而出现平台。为了降低信道估计误差对系统性能的影响,该文进一步提出了一种中继端最优的功率分配策略。 相似文献
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本文针对DF协同通信网络,对两种机会中继选择策略的系统中继概率和复杂度进行了分析,其一是分布式机会中继,通过引入定时器,由各个中继节点根据本地信道状态信息竞争选出最佳中继,其二是集中式机会中继,由目的节点选择候选中继集合中瞬时信噪比最大的节点作为最佳中继。仿真结果表明,集中式机会中继的中断概率性能在高sNR时略优于分布式机会中继策略,但其复杂度和系统开销较高。 相似文献
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在MIMO中继系统中,基于完全信道状态信息的基站、中继节点和终端联合收发机设计方案能够改善系统的误比特率性能,在放大转发(AF)中继的基础上提出了一种基于不完全信道状态信息的联合收发机设计方案.新方案在基站和中继节点的功率都受限条件下,将信道估计误差建模为高斯随机变量,以最小均方误差(MMSE)为准则,采用迭代算法,得到了基站预编码矩阵、中继转发矩阵和终端解码矩阵.该方案与不考虑信道估计误差的方案相比,能够有效地改善系统的均方误差和误比特率性能. 相似文献
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论文研究了存在信道估计误差及天线相关条件下,上行多用户MIMO中继系统的预编码问题,目标是提升系统的误比特率性能。针对基于放大转发中继技术的上行多用户MIMO中继系统,考虑源-中继和中继-目的端信道中存在的信道估计误差及天线相关,提出一种基于不完全信道状态信息(Channel State Information, CSI)的预编码设计方案。首先根据最小均方误差(Minimum Mean-Squared Error, MMSE)准则设计代价函数,以发射端和中继端最大功率为约束条件,通过理论推导求得中继端和发射端的线性预编码矩阵,最后采用迭代下降法得到接收端处理矩阵的闭式解。数值仿真结果表明,在存在信道估计误差和天线相关的条件下,与现有算法相比,所提算法能有效降低系统的误比特率。 相似文献
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基于多中继导频频分复用的协同通信系统信道估计算法 总被引:1,自引:0,他引:1
本文针对频率选择性衰落环境下结合正交频分复用技术的放大转发多中继协同通信系统,提出了基于导频频分复用的频域信道估计算法,包括最小二乘(LS)估计算法和线性最小均方误差(LMMSE)估计算法。理论分析和仿真结果表明,该算法不仅成功分辨了多中继协同通信系统的所有频域信道衰落系数,避免了各中继节点转发的导频符号在目的节点上的混叠干扰,而且减少了频域信道估计所需的导频符号数量和时隙周期长度,提高了协同通信系统的传输效率和频谱利用率,同时显著提高了信道估计的精度,降低了算法的复杂度,具有较高的实用价值。 相似文献
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该文针对频率选择性衰落下的多中继分布式空频编码协同通信系统,提出了基于导频转发新时序的频域信道估计算法,包括最小二乘(LS)估计算法和低阶近似的线性最小均方误差(Lr-LMMSE)估计算法。互相协同的各中继节点在收到源节点广播发送的频域导频符号向量后,通过互不相同的时隙将其转发给目的节点,从而避免了各中继节点转发的导频符号在目的节点上的混叠干扰。理论分析和仿真结果表明,该算法成功地分辨了多中继协同通信系统的所有频域信道系数,其估计精度高,算法复杂度低,具有较高的实用价值。 相似文献
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This work proposes an Expectation–Maximization (EM) based joint channel estimation and data detection algorithm and a time sharing hopped cooperative communication for the downlink of a communication network. The algorithm was applied to the downlink of a single hop relaying network. The relaying technique is a variant of the decode and forward technique. However, it is a time sharing single hop cooperative communication technique applied to a multi-carrier code division multiple access used in cellular networks. The proposed EM algorithm is compared with the minimum mean square estimation (MMSE) method using simulation. In addition, the proposed relaying technique is compared with cooperative communication on the considered cellular network for frequency-selective fading channels. Simulation results illustrate that our proposed EM algorithm performs better than the MMSE algorithm and that our proposed relaying technique is better than the normal case and the cooperative diversity case. 相似文献
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We have investigated the performance and reliability improvement of cooperative free-space optical (FSO) communication over single input single output (SISO) system in this paper. The bit error rate (BER) analysis with quadrature phase shift keying (QPSK), gamma–gamma channel model and pointing error has been demonstrated for SISO and cooperative system. The performance improvement with different combining techniques in cooperative system for different channel environments has been shown in the paper. Markov models for reliability analysis of FSO systems in SISO and cooperative communication have been developed. We have obtained significant increase in availability and mean time between failures with cooperative communication over SISO model. 相似文献
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In this article, we propose an opportunistic transmission protocol for cooperative communication systems with L relay nodes under the influence of fading channels. Unlike the protocols previously known in the literature, and given the fact that direct single-link communication outperforms multilink cooperative communication in terms of throughput for same channel conditions, we adopt the channel conditions of the direct link as a main criterion to use whether the direct link in the transmission or the indirect cooperative link. Different performance metrics are derived to demonstrate the performance of the proposed protocol along with a switching combining with a preferable link scheme. These metrics include the bit error rate (BER), outage probability, signal to interference noise ratio (SNR) gain, average throughput and the sum SNR–throughput product (SSTP). The latter performance metric is introduced to compare the maximum achievable throughput as well as the SNR range at a given quality of service (QoS). Our results show that the proposed opportunistic protocol improves the throughput as compared to the conventional cooperative communication systems for the whole range of average SNR. On the other hand, it improves the coverage range as compared to the direct link communication. 相似文献
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研究协同通信系统的信道估计和符号检测技术,提出一种基于EM(Expectation Maximum)算法的半盲信道估计和迭代检测接收方案。它有利于减少协同通信系统的额外系统开销,并能有效提高协同通信的信道估计精度和系统误码性能。 相似文献
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针对频率选择性衰落信道下的分布式空频编码协同通信系统,提出了基于导频辅助的各种频域信道估计算法,包括最小二乘、线性最小均方误差、低阶近似线性最小均方误差算法,并给出了相应的均方误差性能表达式.理论分析和仿真结果表明本文提出的信道估计算法在协同通信系统中具有很高的实用性和精确度. 相似文献