排序方式: 共有14条查询结果,搜索用时 453 毫秒
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对流层散射通信信道建模及系统性能仿真 总被引:2,自引:1,他引:1
对流层散射通信是一种利用对流层媒质的不均匀性来实现超视距通信的方式.在分析对流层散射信道的统计特性的基础上,根据WSSUS假设建立了快衰落特性下的散射信道仿真模型,并进行了系统性能的实验仿真.同时通过理论计算,得出了该信道误码率的理论曲线,并与仿真结果进行比较,证明了对流层散射信道模型的合理性,该模型为分析系统的性能提供了一个有效的系统平台. 相似文献
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Ersin Gose 《International Journal of Communication Systems》2009,22(3):257-275
This paper presents the performance of the transmit diversity‐multi level turbo codes (TD‐MLTC) over the multiple‐input–multiple‐output (MIMO) channels based on the wide sense stationary uncorrelated scattering (WSSUS). The multi level‐turbo code (ML‐TC) system contains more than one turbo encoder/decoder block in its structure. At the transmitter side, the ML‐TC uses the group partitioning technique that partitions a signal set into several levels and encodes each level separately by a proper component of the encoder to improve error performance. The binary input sequence is passed through the MLTC encoder and mapped to 4‐PSK and then fed into the transmit diversity scheme for high data transmission over wireless fading channels. At the receiver side, distorted multi‐path signals are received by multiple receiver antennae. WSSUS MIMO channel parameters are estimated by using an artificial neural network and an iterative combiner. Input sequence of the first level of the MLTC encoder is estimated at the first level of MLTC decoder. Subsequently, the other input sequences are computed by using the estimated input bit streams of the previous levels. 4‐PSK two‐level turbo codes are simulated for 2Tx?1Rx and 2Tx?2Rx antenna configurations over WSSUS MIMO channels. Here, TD‐MLTC and its efficient implementations are discussed and simulation results are given. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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师小琳 《计算机工程与应用》2011,47(18):157-159
无线WSSUS衰落信道是时变信道,其信道参数随着时间的变化而变化。通常采用的经典跟踪算法(RLS算法)中的重要参数遗忘因子是固定值,这使得算法跟踪时变信道时性能无法保障。对均方误差(MSE)进行了分析,并在此基础上得到基于MSE梯度控制的可变遗忘因子VFF-RLS算法。仿真结果表明MSE分析结果正确;与经典算法相比较,VFF-RLS具有较小的MSE,更适合跟踪WSSUS信道。 相似文献
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无人机测控与信息传输信道的建模与仿真设计 总被引:2,自引:0,他引:2
分析了无人机测控与信息传输系统中传输信道的特点,针对无人机飞行中不同的状态和环境条件,建立了不同的信道模型,并在此基础上,设计了一个可用于无人机测控与信息传输系统设计的信道仿真器,该仿真器通过设置不同的参数,可对无人机飞行中所处的不同通信信道进行仿真,以全面验证无人机测控与信息传输系统中所采用的传输技术性能及接收机性能。 相似文献
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移动通信中无线信道特性的研究 总被引:2,自引:0,他引:2
从等效低通信道的时变冲激响应的相关函数和功率密度谱函数出发,研究了一些描述广义平稳非相关散射(WSSUS)的无线信道特性的统计参数,并对无线移动衰落信道的特性进行分类。分析了3种常见的小尺度多径衰落信道的统计模型,给出了在平坦衰落信道中系统传输比特误码率的一般分析方法。最后,利用这些模型和方法,给出了一些常见数字调制信号的传输误码率的数值结果。结果表明:衰落对无线移动通信系统传输性能的影响是很大的,在实际中应设法消除它。 相似文献
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Osman N. Ucan Kenan Buyukatak Ersin Gose Onur Osman Niyazi Odabasioglu 《International Journal of Communication Systems》2006,19(3):281-297
In this paper, in order to improve error performance, we introduce a new type of turbo codes, called ‘multilevel‐turbo codes (ML‐TC)’ and we evaluate their performance over wide‐sense stationary uncorrelated scattering (WSSUS) multipath channels. The basic idea of ML‐TC scheme is to partition a signal set into several levels and to encode each level separately by a proper component of the turbo encoder. In the considered structure, the parallel input data sequences are encoded by our multilevel scheme and mapped to any modulation type such as MPSK, MQAM, etc. Since WSSUS channels are very severe fading environments, it is needed to pass the received noisy signals through non‐blind or blind equalizers before turbo decoders. In ML‐TC schemes, noisy WSSUS corrupted signal sequence is first processed in equalizer block, then fed into the first level of turbo decoder and the first sequence is estimated from this first Turbo decoder. Subsequently, the other following input sequences of the frame are computed by using the estimated input bit streams of previous levels. Here, as a ML‐TC example, 4PSK 2 level‐turbo codes (2L‐TC) is chosen and its error performance is evaluated in WSSUS channel modelled by COST 207 (Cooperation in the field of Science & Technology, Project #207). It is shown that 2L‐TC signals with equalizer blocks exhibit considerable performance gains even at lower SNR values compared to 8PSK‐turbo trellis coded modulation (TTCM). The simulation results of the proposed scheme have up to 5.5 dB coding gain compared to 8PSK‐TTCM for all cases. It is interesting that after a constant SNR value, 2L‐TC with blind equalizer has better error performance than non‐blind filtered schemes. We conclude that our proposed scheme has promising results compared to classical schemes for all SNR values in WSSUS channels. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献