共查询到20条相似文献,搜索用时 218 毫秒
1.
2.
3.
在空间多径信道垂直线列阵通信中,由于多阵元码间干扰导致信道失衡,误码率较高,需要进行信道均衡设计。传统方法采用随机码扩频方法进行通信信道均衡,扩频信号经高放和混频后导致非线性失真,均衡效果不佳。文中提出一种基于直接序列扩频的线列阵通信信道均衡算法。基于PTRM技术构建了垂直线列阵通信的空间多径信道模型,采用直接序列扩频方法设计码间干扰抑制算法,利用垂直线列阵结构对PTRM时间压缩性能,接收到的扩频信号经高放和混频后,对中频扩频的调制信号进行相关解扩,重组多垂直线列阵的径分量,实现信道均衡。仿真结果表明,采用该算法进行垂直线列阵通信,信道均衡性能和码间干扰抑制性能较好,并有效降低了误比特率,改善了通信质量。 相似文献
4.
随着电磁环境越来越复杂,全球卫星导航系统(GNSS)受到的干扰越来越多。基于均匀间距阵列的抗干扰算法已广泛运用于GNSS干扰抑制中,但是均匀线性阵列抑制干扰的性能受到天线阵元个数和阵列孔径的严格限制。本文提出了一种基于联合互质阵列的卫星导航抗干扰算法,能够在不增加阵元的情况下获得较大的阵列孔径,提高了干扰来向估计性能且不需要知道干扰个数。该方法首先利用互质阵列的空间谱估计方法估计出干扰来向,然后,利用估计出的干扰来向构造干扰子空间,并通过正交子空间投影算法抑制干扰。算法提高了卫星导航系统的抗干扰性能,仿真实验验证了该算法的有效性。 相似文献
5.
6G星地融合网络对卫星通信系统提出了高速率低时延低能耗的要求,由于星地链路信道环境复杂多变且容易受到干扰,需要研究干扰场景下的低成本可实现阵列架构及算法。针对这一问题,设计了一种数模混合阵列结构,子阵采用50%稀疏馈电以及最小二乘波束形成算法,超阵采用最小二乘与线性约束最小方差波束形成算法,并理论分析了阵列结构的可行性,证明子阵的零点能够抑制超阵的栅瓣。仿真结果表明,该结构以更低的复杂度实现了大规模阵列的效果,波束方向图指向明确且零陷深度足够,对干扰的抑制明显,获得了接近理想阵列增益的BER性能。 相似文献
6.
7.
8.
9.
文[6]提出在数字移动通信中子带滤波器组处理可以提高不同阵元信号的相关性,从而能改善自适应阵列抑制码间干扰(ISI)和共信道干扰(CCI)的能力.在文[6]的基础上,本文研究了子带滤波器组在宽带自适应天线旁瓣相消中的应用,对其原理进行了理论分析,提出了有效的子带处理方法.经研究表明,子带滤波器组处理能有效增加主、辅助天线信号的相关性,从而提高系统干扰相消比.而且适当的过采样能使系统干扰相消比进一步提高.计算机仿真结果和实测雷达数据处理结果证实了子带处理方法的有效性和理论分析的正确性. 相似文献
10.
频率分集阵列多输入多输出(FDA-MIMO)雷达发射阵列中各阵元的载频相对于起始阵元存在频率偏移。基于频率分集阵列联合波束图存在的角度距离二维相关性,结合空间自适应波束形成技术可用来抑制主瓣欺骗干扰。针对FDA-MIMO 雷达波束形成抑制主瓣欺骗干扰时存在的距离周期性问题,提出了一种采用对数频率偏移来消除距离周期性的方法。该方法用对数频率偏移代替常用的线性频率偏移,克服了FDA-MIMO 雷达联合波束图的距离周期性,取得了更好的抗干扰效果。仿真结果验证了该方法的有效性。 相似文献
11.
Fonollosa Javier R. Zvonar Zoran Fonollosa José A.R. Català Joan 《Wireless Personal Communications》1998,6(1-2):179-196
Cochannel interference is usually a major limitation to the performance of mobile wireless systems. Examples of different forms of cochannel interference include multi-access interference in CDMA systems and cochannel interference resulting from frequency reuse in TDMA systems. In order to mitigate the interference from other users we present a blind multiuser receiver which utilizes array observations and performs both spatial and temporal processing of the received signal. The presented technique is completely blind in the sense that no signature sequences, channel state or spatial location needs to be known a priori, nor use of a training sequences, channel state or spatial location needs to be known a priori, nor use of a training sequence is required for the adaptation. The diversity introduced by the array observations can be efficiently combined with the use of CDMA signature sequences. After initial convergence, a reliable estimate of the combined temporal and spatial signature for each user is provided that can be employed by a multiuser receiver of lower complexity. 相似文献
12.
Maw-Lin Leou Chien-Chung Yeh Hsueh-Jyh Li 《Vehicular Technology, IEEE Transactions on》2000,49(1):1-10
The combination of the adaptive array and equalizer (AE) has been developed for suppressing the cochannel interference and the intersymbol interference (ISI) in mobile communications. In this paper, a novel hybrid of the adaptive array and equalizer (NHAE) system is proposed to combat the problems of insufficient degrees of freedom and mainbeam multipath interferers. The NHAE utilizes a modified training sequence to adjust the weight vector of the array that leads the array to cancel only the cochannel interferers. The ISI which is caused by the multipath interferers and the transmission system is removed by the equalizer following the array. Therefore, the array in the NHAE may need a fewer number of the elements than the conventional array which cancels both the cochannel interferers and multipath interferers. Besides, the presence of the mainbeam multipath interferers, which may seriously degrade the performance of the AE, has much less effect on the NHAE since it is suppressed by the equalizer instead of by the array. Simulation results are presented to demonstrate the merits of the NHAE 相似文献
13.
It has been shown through simulation results that the interference adaptive dynamic channel allocation (IA-DCA) scheme is a promising resource allocation strategy in time/frequency-division multiple-access (TDMA/FDMA) communication systems. The major obstacle in analyzing IA-DCA is the computation of cochannel interference without the constraint of conventional channel reuse factors. To overcome this difficulty, one needs a computationally efficient representation which can approximate the interference distribution accurately. For this purpose, a concept called channel reuse zone (CRZ) is introduced. Based on this new concept, both downlink and uplink cochannel interference are computed with two different propagation models, namely, a simplified deterministic model and a shadowing model. The results are then used to calculate the outage probability of the idealized, interference adaptive maximum parking (IAMP) scheme. Finally, as a significant contribution, an asymptotic performance bound for the two-way IA-DCA strategy is derived 相似文献
14.
15.
Electronically steerable passive array radiator (ESPAR) antennas are considered to have the capability to form a beam spatially toward the desired signal with the lowest cost. We propose a method to realize space-time adaptive filtering (STAF) by employing ESPAR antennas for TDMA or CDMA signal waveforms. According to the method, the cochannel interference signals are spatially suppressed by the adaptive beamforming, and the intersymbol interference signals are suppressed by the temporal waveform-based adaptive equalization. Simulation results show the effectiveness of the proposed method in the signal environment of a local network communication system. 相似文献
16.
Bottomley G.E. Molnar K.J. Chennakeshu S. 《Vehicular Technology, IEEE Transactions on》1999,48(5):1321-1331
the capacity and transmission quality in cellular systems can be improved by using receivers that mitigate cochannel interference and multipath propagation. In this paper, a class of multichannel maximum likelihood sequence estimation (MLSE) receivers is developed for this purpose. Interference mitigation is accomplished via adaptive antenna arrays, while multipath propagation is combated via MLSE. Practical considerations are included, such as fixed front-end filtering, sampling, and estimation of parameters from received samples. Maximal ratio combining, conventional array processing and metric combining (MC) are shown to be special cases of the proposed receivers. Performance is evaluated for π/4-shift DQPSK, using the parameters and transmission format of the time-division multiple-access (TDMA)-based IS-136 (D-AMPS) digital cellular standard. Semi-analytical performance predictions are developed which confirm simulation trends. The results show that these receivers can operate at significantly lower carrier-to-interferer (C/I) levels than conventional MC receivers 相似文献
17.
The prediction of edge element behavior is a common problem during the design of large array antennas. The performance of the center elements can be approximated by an infinite array model, but the edge element patterns and active reflection coefficients cannot. The full element-by-element analysis of a large finite array is either excessively time consuming or impossible due to the computer power required. A study has recently been carried out to develop and test methods of fully predicting large array performance using infinite array data. The methods devised are presented, together with comparisons of predicted performance and measured data from a 163-element WG-16 array 相似文献
18.
Kohno R. Imai H. Hatori M. Pasupathy S. 《Selected Areas in Communications, IEEE Journal on》1990,8(4):675-682
In the realization of code-division multiple access based on a spread-spectrum communication system, i.e. spread-spectrum multiple access (SSMA), reduction of cochannel interference is an important problem. An adaptive array antenna system is proposed that includes a cancellor of cochannel interference, which can improve performance by a combination of temporal and spatial filtering. While the adaptive array suppresses interference sources with arrival angles different from those of the desired user, the adaptive digital filter-canceller rejects those whose arrival angles are the same as those of the desired user. The proposed system can achieve stable acquisition and low error rate of demodulated data even in a heavy-interference channel where a conventional array antenna system cannot achieve satisfactory acquisition 相似文献
19.
20.
The constant modulus (CM) array is a blind adaptive beamformer capable of recovering a narrowband signal among several cochannel sources without using a pilot or training signal. It is a conventional weight-and-sum adaptive beamformer whose weights are updated by the constant modulus algorithm. An adaptive signal canceller follows the beamformer to remove the captured signal from the array input and to provide an estimate of its direction vector. Based on a Wiener model, we investigate the steady-state properties of the CM array and the signal canceller. For mutually uncorrelated sources and noise, it is shown that the signal canceller exactly removes the source captured by the array. Thus, identical stages of the CM array and signal canceller may be used in a multistage system to recover several cochannel sources. Computer simulations are presented to verify the analytical results and to illustrate the transient behavior of the system 相似文献