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LTE_A系统是对LTE系统的进一步优化和过渡,其中新添了许多新技术,其中有小区覆盖扩展CRE(Cell Range Extension)技术。CRE技术能有效均衡宏基站和微微基站的负载,但是单独采用CRE方案,处于微微基站扩展区域的微微基站用户会受到来自宏基站的强烈干扰。为了抑制来自宏基站的强烈干扰,提出了一种时频域相结合的干扰协调方案,在控制信道、数据信道中传输的信息通过功率控制与正交频率分配相结合从而达到抑制干扰的目的。通过Matlab仿真,结果表明该方案不仅能够很好地改善由CRE技术带来的干扰问题,而且很好地改善了小区吞吐量及边缘用户速率。 相似文献
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在宏基站和微微基站(Macro-Pico)的异构网络中,资源分配可以有效地抑制基站间的干扰。基于降低用户的干扰和提高系统的吞吐量,提出一种自适应的频率资源分配方案。考虑分配给宏基站的每个资源块,如果距离宏基站较近的微微基站用户所受到的干扰高于最高限,采用不给宏基站分配这个资源块的方法,从而降低其对邻近微微基站用户的干扰,保证微微基站用户一定Qo S(Quality-of-Service)。系统仿真结果表明,与正交频率资源分配方案和共信道频率资源分配方案相比较,所提出的自适应频率资源分配方案降低了干扰和提高了系统的吞吐量。 相似文献
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目前基站上行干扰分析缺乏有效工具,工作效率低下.为提高基站上行干扰分析效率,分析了多种上行干扰产生的原因及其时频域特征,总结出干扰识别的规则,并开发出一种干扰分析工具.该工具根据多天的小时级PRB干扰话统绘制时频域干扰波形图、分析并给出干扰类型;大大提高了干扰分析效率,尤其在分析大量小区干扰时效果更为突出.该工具已在各... 相似文献
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该文考虑骨干网只能进行少量信息交换的多载波异构蜂窝网络,研究微系统进行下行传输时对宏系统的干扰协调问题。针对多载波宏基站和微基站之间存在频偏的场景,在保证对宏用户的干扰小于预定干扰门限的前提下,以最大化微系统数据率为目标,在已知瞬时干扰信道和统计干扰信道信息的条件下分别设计最优和次优发射预编码。分析和仿真的结果表明,次优算法只需迭代一次就能达到接近最优算法的性能,因此具有较低的计算复杂度。所提出的方法只需要在宏基站和微基站之间通过骨干网交换少量信息,具有较低的信息共享资源开销。所提出的方法适用于微基站附近存在多个宏用户的场景。 相似文献
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一种TD-LTE系统上行干扰三维分析方法 总被引:3,自引:3,他引:0
TD-LTE上行干扰水平是评估网络质量的重要指标,当网络受到上行干扰时,上行吞吐量、尤其是小区边缘用户的上行吞吐量将受到影响,干扰严重时甚至会影响用户的接入性能。本文对TD-LTE系统上行干扰问题进行研究,提出干扰频域、时域及地理分布特征三维联合分析方法,实现了TD-LTE系统上行干扰的全方位分析,可大大提高TD-LTE干扰优化与排查工作的效率及准确性。 相似文献
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在通用移动通信系统(Universal Mobile Telecommunications System,UMTS)异构网络中,理论分析了宏基站对微微(Pico)小区边缘用户的下行干扰问题。在传统空白帧(ABS)方法的基础上,提出了一种干扰避免策略,其主要思想是通过联合时域ABS策略和空域基于码本限制的策略提高传统ABS策略的系统性能,即在ABS子帧上,宏基站并不是完全不发送数据,而是采用码本受限的预编码进行传输。限制的码本可以根据宏小区自身的负载动态进行更改,并通过广播传递给低功率节点(Low Power Node,LPN),LPN根据得到的信息进行边缘用户的调度。仿真结果表明,提出的方法在最差5%用户吞吐率比ABS方法略有下降的情况下,使用户平均吞吐量得到了提升。 相似文献
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Hsueh-Jyh Li Ta-Yung Liu 《Vehicular Technology, IEEE Transactions on》2003,52(4):752-760
Different beamforming techniques are employed in a wideband code-division multiple-access base station, and their uplink and downlink signal-to-interference-plus-noise ratio (SINR) performances are compared. It is found that the direction of arrival (DOA) method and the complex conjugate method have almost the same uplink SINR performance, but the complex conjugate method shifts the downlink main beam direction slightly due to the difference between the uplink and downlink carrier frequency. However, the degradation in the downlink mean SINR performance is less than 1 dB compared with that obtained by the DOA method. In the downlink, the SINR performances obtained by the single-beam method and multiple-beam beamforming technique are compared. It is found that the single-beam method has a poorer SINR performance in the low SINR region because it is more likely to suffer from deep fading. In the moderate or high SINR regions, the single-beam method has a much better SINR performance because it has a higher gain in the main path direction and a smaller angular coverage of the mainlobe, which results in a stronger signal level and smaller multiple-access interference at the mobile receiver. 相似文献
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We study the problem of power efficient multiuser beamforming transmission for both uplink and downlink. The base station is equipped with multiple antennas, whereas the mobile units have single antennas. In the uplink, interference is canceled by successive decoding. In the downlink, ideal "dirty paper" precoding is assumed. The design goal is to minimize the total transmit power while maintaining individual SINR constraints. In the uplink, the optimization problem is solved by a recursive formula with low computational complexity. The downlink problem is solved by exploiting the duality between uplink and downlink; thus, the uplink solution carries over to the downlink. In the second part of the paper, we show how the solution can be applied to the problem of rate balancing in Gaussian multiuser channels. We propose a strategy for throughput-wise optimal transmission for broadcast and multiple access channels under a sum power constraint. Finally, we show that single-user transmission achieves the sum capacity in the low-SNR regime. We completely characterize the SNR-range where single-user transmission is optimal. 相似文献
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The performance of massive multiple-input multiple-output (MIMO) system is limited by pilot contamination. To reduce the pilot contamination, uplink and downlink precoding algorithms are put forward based on interference alignment criterion. In the uplink receiving processing, the target function aligns the pilot contamination and the interference signals to the same null space and acquires the maximal space degree of the desired signals. The uplink receiving precoding matrix is solved on maximal signal to interference plus noise ratio (SINR) criterion considering the impact of the pilot contamination on channel estimations. The uplink receiving precoding matrix is used as the downlink transmitting precoding matrix. Exploiting the channel reciprocity, it is proved that, if the uplink receiving precoding matrix achieves maximal S1NR, the identical precoding matrix can be used in the downlink transmission and acquires maximal signal to leakage plus noise ratio (SLNR). Simulations show that the spectrum efficiency of the proposed algorithm can reach about 1.5 times higher than that of popular matched filtering (MF) precoding algorithm, and about 1.1 times higher than multi-cell minimum mean square error (MMSE) precoding algorithm. The performance of the proposed algorithm can be improved approximately linearly with the increasing of the number of antennas. 相似文献
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When multiple single-antenna half-duplex (HD) nodes communicate with a full-duplex (FD) base station equipped with multiple transmit and receive antennas, the uplink nodes would generate inter-node interference (INI) on the downlink nodes. We propose a base station assisted INI suppression scheme. The scheme is to design a proper amplify-and-forward matrix at the base station so that the sum achievable rate of the uplink and downlink is maximized. We derive the close-form expression of the amplify-and-forward matrix, which is the product of a parameter optimization and a zero-forcing beamforming (ZFBF) matrices. Finally, we investigate the performance of the proposed INI suppression scheme in a single cell. 相似文献
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Richard E. Cagley John J. Shynk Richard P. Gooch 《Wireless Personal Communications》2007,41(4):563-580
Due to near-far effects and multiple-access interference, several types of multiuser detectors have been developed in recent
years to reliably demodulate user signals in a code-division multiple-access (CDMA) system. The downlink of Interim Standard
95 (IS-95) is particularly well suited to one such detector known as the successive interference canceler (SIC). In order
to keep the receiver complexity low, entire base station signals are typically canceled in the receiver in a sequential manner.
However, for the SIC to operate effectively, a base station signal that is being canceled must be reconstructed with enough
accuracy such that sufficient interference power is removed for the subsequent base station to be reliably detected. If this
is not possible, it may be necessary to employ techniques, specific to the signal format specified in the IS-95 downlink,
which enhance the received signal-to-interference-plus-noise ratio (SINR). In this paper, we explore the performance gains
achieved with several SINR enhancement techniques, and present computer simulations to demonstrate this improvement for example
cochannel signal scenarios. 相似文献
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简要分析了目前室内覆盖规范存在的对于上下行链路不平衡,以及重视场强不重视干扰的问题。对于其上行干扰的成因进行了详细分析,并且给出了问题出现的概率,以及相应的定位与处理方法。对室分系统的设计规范和测试方法提出了改进建议。 相似文献
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重点介绍如何有效地进行CDMA基站上行干扰的定位和清除,详细介绍干扰定位和清除的方法和流程,并给出复杂干扰定位和清除案例。 相似文献
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Zhou Yan 《Wireless Communications and Mobile Computing》2009,9(8):1113-1124
This work presents a space‐frequency prefiltering scheme for slowly time‐varying TDD MC‐CDMA downlink communications with multiple antennas at the base station (BS). Unlike the conventional spatially uncorrelated block fading channel model, both channel variation in each packet and spatial correlation are considered in the design. In the TDD mode, the mobile terminals (MTs) transmit training signals at the end of each uplink packet. In the following downlink packet, the BS computes the signal weights on different antennas and subcarriers for each MT in each symbol period based on the channel state predicted from the received training signals. The goal is to minimize the total required transmit power while keeping the received signal‐to‐interference‐plus‐noise ratio (SINR) as the target for each MT. Moreover, the maximum packet length for satisfying the SINR requirements has been determined. The results indicate that the total required transmit power can be reduced by a lower mobile speed or more BS antennas. As a result, the maximum packet length can be extended in virtue of the power reduction. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献