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101.
针对广泛存在于无线通信环境中的阴影效应对系统性能影响非常大的问题,采用与传统的微分集技术相比,能够有效地对抗这种阴影衰落的分布式天线技术来解决这个问题.为了获得该条件下系统的理论性能,分析了采用最大比合并和相干等增益合并分集的广义分布式天线系统.借助lognormal近似法,给出了其中断概率和误码率性能的高精度解析结果.分析表明,在存在阴影衰落的情况下,这种广义分布式天线系统能够同时获得较大的微/宏分集增益,非常适合未来的无线小区环境. 相似文献
102.
针对空间受限平台跳频(FH)通信系统同址干扰的特点,提出共用天线结合导频的跳频同址干
扰抵消(CAP-FH-AIC)算法. 只需在自适应定频同址干扰抵消系统的基础上增加导频产生模
块和窄带滤波器,通过将多参考输入自适应跳频干扰抵消(M-AIC)转化为单参考输入自适应
定频同址干扰抵消(S-AIC)的方式即实现本算法. 算法实现简单、性能稳定,使跳频同址干
扰抵消可以获得和定频同址干扰抵消一致的性能. 相似文献
扰抵消(CAP-FH-AIC)算法. 只需在自适应定频同址干扰抵消系统的基础上增加导频产生模
块和窄带滤波器,通过将多参考输入自适应跳频干扰抵消(M-AIC)转化为单参考输入自适应
定频同址干扰抵消(S-AIC)的方式即实现本算法. 算法实现简单、性能稳定,使跳频同址干
扰抵消可以获得和定频同址干扰抵消一致的性能. 相似文献
103.
104.
在移动通信速度优化问题的研究中,终端速度的估计对长期演进(LTE)系统性能有重要的影响.针对传统信道自相关函数法在高速场景下应用受限的问题,提出了一种新的联合速度估计算法.上述算法在中速和低速场景下采用信道自相关函数法进行估计,在高速场景下采用频偏估计法进行估计,利用归一化接收功率标准差进行场景判断并在两种方法中切换,以提高速度估计精度.仿真结果表明,联合估计算法在低速、中速以及高速场景下均具有较高的估计精度,具有较好的应用价值. 相似文献
105.
王晓晶 《计算机工程与科学》2014,36(10):1906-1910
天馈线系统产生的无源互调干扰有其独特性,实践中多采用测试仪表现场排查方法,存在效率低下、准确率低等问题。针对这些问题,提出了利用基站系统作为互调检测硬件平台的天馈线干扰非现场排查法,可以通过干扰频谱数值对比,从复合干扰中分离出由天馈系统引发的互调干扰并对其进行定性,因而提高了检测排查的效率和准确性。 相似文献
106.
基于0.13μm CMOS工艺,设计了一种采样率达到1 MS/s的10位逐次逼近模数转换器,其中逐次逼近数字控制逻辑采用全定制的方法,减小了数字单元的面积和功耗;比较器中的预放大器分别采用了二极管连接和开关管复位的方式将各级运放的输出短接,加快比较速度,最后一级锁存器采用改进的两级动态锁存器,进一步提升比较速度的同时降低了失调误差。实验结果表明,1.2 V电源电压下,所设计的ADC采样率达到1 MS/s,输入信号频率为12.5 kHz时,测得的输出信号信噪比为54.47 dB,SFDR为45.18 dB。 相似文献
107.
To improve the capacity of initial ranging (IR) users simultaneously accessing into network and enhance the performance of the IR, a novel IR algorithm is presented for the orthogonal frequency division multiple access systems with the smart antenna. The beamforming weight vectors provided by the antenna array are introduced for the IR users, and the procedures of the multiuser parameter estimation and the interference cancellation are designed. The proposed method can improve the accuracy of the channel estimation of active paths and efficiently reduce the residual multiple access interference. Simulation results show that the proposed method has a much better performance than the available successive multiuser detection and interference cancellation algorithm and accommodates more active ranging users simultaneously accessing into a cell. 相似文献
108.
Coupled gas chromatography with electroantennographic detection (GC-EAD) using antennae of adult female Manduca sexta was employed to screen for olfactory stimulants present in headspace collections from four species of larval host plants belonging to two families: Solanaceae—Lycopersicon esculentum (tomato), Capiscum annuum (bell pepper), and Datura wrightii; and Martyniaceae—Proboscidea parviflora. Headspace volatiles were collected from undamaged foliage of potted, living plants. GC–EAD revealed 23 EAD-active compounds, of which 15 were identified by GC-mass spectrometry. Identified compounds included aliphatic, aromatic, and terpenoid compounds bearing a range of functional groups. Nine EAD-active compounds were common to all four host plant species: (Z)-3-hexenyl acetate, nonanal, decanal, phenylacetaldehyde, methyl salicylate, benzyl alcohol, geranyl acetone, (E)-nerolidol, and one unidentified compound. Behavioral responses of female moths to an eight-component synthetic blend of selected tomato headspace volatiles were tested in a laboratory wind tunnel. Females were attracted to the blend. A comparison of responses from antennae of males and females to bell pepper headspace volatiles revealed that males responded to the same suite of volatiles as females, except for (Z)-3-hexenyl benzoate. EAD responses of males also were lower for (Z)- and (E)-nerolidol and one unidentified compound. Electroantennogram EAG dose–response curves for the 15 identified EAD-active volatiles were recorded. At the higher test doses (10–100 g), female antennae yielded larger EAG responses to terpenoids and to aliphatic and aromatic esters. Male antennae did respond to the higher doses of (Z)-3-hexenyl benzoate, indicating that they can detect this compound. On the basis of ubiquity of the EAD-active volatiles identified to date in host plant headspace collections, we suggest that M. sexta uses a suite of volatiles to locate and identify appropriate host plants. 相似文献
109.
110.
A low profile circularly polarized (CP) antenna with reconfigurable polarization is designed and presented, which can radiate omnidirectional patterns that can be switched between left‐hand circularly polarized (LHCP) and right‐hand circularly polarized (RHCP). A pair of arc‐shaped complementary dipoles is acted as reconfigurable elements by bridging four pin diodes at the dipole arced arms. A meander phase shift line is employed to connected the arc dipole arms and plate cavity to adjust the phase relationship of two sources. The proposed antenna exhibits the omnidirectional radiation pattern by combining six identical elements placed in a circular array configuration. 24 p‐i‐n diodes are exploited to six elements, by manipulating the dc bias voltage across the diodes, the polarization state of the antenna can be switched. The patterns of the antenna are similar to that of a dipole, but its size is only about Φ0.87 × 0.029λ0 at 5.8 GHz. The overlapped bandwidth of measured 3‐dB axial ratio (AR) and 10‐dB return loss is 5.724‐5.87 and 5.738‐5.91 GHz for two polarization states, which are right on the target of ISM band. It can be well adapted to medical diagnosis systems. 相似文献