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基于Alamouti提出的BPSK调制下空时分组码在Rayleigh衰落信道中的简单分集方案。推导出多发射和多接收天线系统中正交空时分组码在Nakagami衰落信道的BPSK调制下的比特差错率的最小距离球界,并推广到在高阶调制下衰落信道中系统符号差错率的性能。仿真分析和比较了空时分组码的多天线系统中发射和接收天线分集增益,以及信道相关参数的变化对系统误比特性能的影响。 相似文献
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基于Alamouti提出的BPSK调制下空时分组码在Rayleigh衰落信道中的码性能原理,推导出高阶(M ary)调制下Rician衰落信道中空时分组码的符号差错率的最小距离球界,并进行计算机仿真分析了两信道下引入空时分组码的多天线系统中发射和接收天线的分集增益,发射天线数量的“地板效应”以及Rician因子K对符号差错性能的影响。 相似文献
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提出了一种用于正交空时分组码(OSTBC:Orthogonal Space-Time Block Code)多发射天线多接收天线系统的盲自适应接收机.该方法主要利用了正交空时分组码的内在特性,给出了一个针对正交空时分组码多发射天线多接收天线系统的无约束代价函数,分析了该函数的全局最小值点.利用该无约束代价函数,通过投影逼近方法给出了递推最小二乘(RLS)自适应算法实现.仿真结果表明:该接收机可以很好的跟踪衰落信道的变化,在不利用导频信号的情况下很好的还原出原始的传输信号. 相似文献
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《Communications Magazine, IEEE》1996,34(10):152-154
This article presents simple formulas which are helpful in predicting interference reduction and capacity increase provided by switched-beam intelligent antenna systems for cellular telecommunications. The key element of this type of intelligent antenna system is an m×M switching matrix where m is the number of beams and M is the number of radio channel units. The system capacity is related to the complexity of the switching matrix. A 12-beam switched-beam antenna system can provide 100 percent capacity increase over a conventional three-sector (three-beam) antenna system 相似文献
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几种多天线系统的信道容量比较 总被引:3,自引:1,他引:2
分布式天线、智能天线和扇区天线是三种能大大提高无线通信系统容量的技术,本文比较了这三种多天线系统的信道(Shannon)容量.假设每个用户在所有接收天线上的总功率相等,分析表明分布式天线和扇区天线的信道容量远大于智能天线的信道容量,而传统的观点认为智能天线在抑制干扰时要比扇区天线的性能更好,从而获得更大的系统容量.另外我们分析了分布式天线在渐近条件下的信道容量,即用户数K和载波数M都趋近无穷大,而保证α=K/M一定.分析表明在α较大时,分布式天线与比扇区天线的信道容量差趋近常数0.44比特/秒/维,但是如果考虑分布式天线的分集增益,那么分布式天线的信道容量要远大于扇区天线. 相似文献
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In this paper, the multiple access capacity of an Mary pulse position modulation (PPM) impulse radio (IR) system with antenna array is analyzed in dense multipath environments. An antenna array with Rake receivers is used to capture the signal energy from multipaths. Multiple access performance of the system is evaluated in terms of number of supported users for a given bit error rate and bit transmission rate with different number of antenna elements and selected paths. Numerical results show that the multiple access capacity of an M-ary IR system can be improved significantly by increasing the number of antenna elements and/or by adding more paths coherently at the receiver. 相似文献
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超大规模多输入多输出(Multiple-Input Multiple-Output,MIMO)天线系统是6G的关键技术,由于天线单元间距很小,多个天线单元的互耦效应是影响其性能的因素之一。建立了基于石墨烯基贴片天线阵列-子阵列架构的超大规模MIMO天线系统,推导出了互耦效应影响下的信道容量表达式。通过电磁场数值计算仿真了超大规模MIMO天线系统的信道容量,结果表明,在不考虑互耦效应时,超大规模MIMO天线系统的信道容量与子阵列天线单元数、子阵列数以及发射机功率正相关;在互耦效应的影响下,系统的信道容量降低,互耦效应的强弱与子阵列天线单元的间距有关,天线单元间间距越小,相邻天线间的互耦效应越明显,系统的信道容量越小。该仿真结果可以为6G中超大规模MIMO天线系统的设计提供参考。 相似文献
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在基于分布式发射天线的多入多出(MIMO)系统中,由于各发射天线的发射信号不同时到达接收端,用于信道估计的导引设计及发射方法存在一定困难。针对这一问题,该文提出一种无需信道估计的分布式MIMO差分编码及检测方法:发送端将发射矩阵进行相位差分调制后发射,接收端利用前后接收量判断相位信息恢复出发送端数据信息。该方法频谱效率与V-BLAST相同,适用于任意发射天线数和接收天线数,且不要求接收天线数大于发射天线数。仿真结果表明,在不同信道传播时延情况下,误码率性能不同。 相似文献
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When array antennas are used for wide-frequency operation a difficulty with grating lobes is encountered at the upper frequency end of the operating band. This paper points out that the use of arrays for transmission and reception with different interelement spacings can be used to extend the operating frequency band in a radar system. The principle of transmitting-receiving arrays with different illuminations was used by Mattingly [2] to lower the sidelobe level of a radar array antenna. Birge [3] used it to reduce the number of elements in an array while preserving the resolution. The same principle is used in this paper to extend the operating frequency bandwidth of a radar antenna system. Relationships for an optimized radar array antenna system are derived. The criterion for optimization is the maximum bandwidth with a given total number of elements. It is shown that in an optimized system the number of elements in one array antenna is one greater than in the other, and the ratio of interelement spacings is inversely proportional to the square of the number of elements in the respective arrays. Based on these conditions, a functionk is computed and tabulated. This function determines the number of grating lobes permissible in the specified angular sector, without overlap, as a function of the number of elements in the two arrays. An application to a high frequency (HF) ionospheric radar antenna system, now under construction, is used as an illustration of the principles outlined in the paper. 相似文献
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Phased array calibration 总被引:2,自引:0,他引:2
Calibration of a phased array antenna while the antenna is in service can be a complex and time-consuming procedure that affects use of the antenna and imposes an unacceptable overhead on the system. The procedure described herein uses a maximum likelihood algorithm to minimize the number of measurements, thus reducing the impact on the system and shifting the overhead to a remote site 相似文献
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Reverse link erlang capacity of multiclass CDMA cellular system considering nonideal antenna sectorization 总被引:1,自引:0,他引:1
Castaneda-Camacho J. Uc-Rios C.E. Lara-Rodriguez D. 《Vehicular Technology, IEEE Transactions on》2003,52(6):1476-1488
In this paper, the effect of antenna sectorization in the reverse link erlang capacity of a multiclass code-division multiple-access (CDMA) cellular system is studied. Traditionally, it has been considered that the capacity is multiplied by a factor equal to the number of sectors introduced. This is true only in the ideal antenna sectored system. However, due to the nonideal antenna radiation pattern, the sectorization gain is smaller than the number of sectors. Our contribution is the analytical study of the effect of nonideal antenna patterns on the capacity of a multiclass CDMA system. We also present an approximated analysis of the erlang capacity, considering that blocking in CDMA occurs when the interference reaches a predetermined level above the background noise level of mainly thermal origin. The analysis also includes the effects of imperfect power control and service activity detection. We found that the capacity losses due to the consideration of antenna sectorization are about 20.20% for the nonideal antenna radiation pattern and 30.32% for the evaluated commercial radiation pattern. This percentage loss implies that the sectorization gain is approximately 2.39 for a nonideal antenna pattern and 2.09 for a commercial antenna pattern in typical conditions, /spl mu/=4 and /spl alpha/=8 dB. 相似文献
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In this paper, a framework is presented to analyze the performance of multiuser diversity (MUD) in multiuser point-to-multipoint (PMP) MIMO systems with antenna selection. Based on this framework, the tight closed-form expressions of outage capacity and average symbol error rate are derived for the multiuser transmit antenna selection with maximal-ratio combining (TAS/MRC) system, by which we show how and with what characteristics antenna selection gains, MIMO antenna configurations and fading gains impact on the system performance, with an emphasis on the study of multiuser diversity influence. From both theoretical and simulation results, our study shows that in multiuser PMP TAS/MRC systems an diversity order equals to the product of the number of transmit antennas, number of receive antennas and number of users can be achieved; what's more, users plays a key role in the system performance and can be viewed as equivalent 'virtual" transmit antennas, which is the source of the multiuser diversity inherent exists in the multiuser system. This kind of diversity can be efficiently extracted in the design of multiantenna systems. 相似文献