共查询到18条相似文献,搜索用时 546 毫秒
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随着无线通信用户数量的指数性增长,宏小区用户数量超负荷,边缘用户受邻近微小区的干扰逐步加剧,导致整个小区的通信服务质量降低。为解决这些问题,针对双层无线异构网络场景,结合粒子群优化算法和小区范围扩展技术动态地调整微小区服务区域,寻找出小区范围扩展最优偏置值,缓解宏小区高热点区域负载压力并提高系统用户平均传输速率。仿真结果表明,相比静态小区范围扩展偏置值算法,利用动态小区范围扩展偏置选择的宏小区用户数量下降了近10%,即卸载了部分宏用户使其接入微小区,达到为宏小区减负的效果;微小区边缘用户的信干噪比相应提高了约2 dB,系统用户平均传输速率提高,整个小区的通信服务质量有较大提升。 相似文献
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提供了一种提高蜂窝OFDMA小区边缘用户上行链路传输效率的方法,它利用小区内扇区分集提高误比特率性能,并利用小区间分组分集降低分组重传次数.对小区边缘用户,提出在同一小区的不同扇区之间利用微分集改善接收信号质量,即用户所属扇区和接收用户信号最强的相邻扇区均接收等增益合并这两个扇区用户发射数据分组.同时,采用多基站协作的分组分集方法,除本地基站接收目标用户发射分组并经检验后传送到网关之外,根据当前负载与可支持负载之比最小的原则选择与该用户相邻基站,且该基站也接收该用户数据包并检验后把该分组传送到网关,无线网关把接收到分组重建为数据报后接入IP网络.同时,当多个用户均要求该相邻基站参与协作处理时,为降低小区间干扰,采用调度器保证各用户在给定时隙内仅有一个用户向相邻基站发射信号.通过联合小区内分组合并和小区间分组分集,提高了系统传输效率. 相似文献
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LTE是新一代通信技术的代名词,它对现有3G系统的网络结构和无线接入方式都有较大改进.在简要介绍LTE系统的网络架构及切换功能的基础上,重点介绍并比较了2种LTE切换自优化算法:常见的用户速度的负载均衡算法有效地降低了系统的掉话率,使系统的整体性能得到提高,但没有考虑到目标小区资源变化的情况;基于RSRP/RSRQ负载均衡算法综合考虑了源小区和目标小区的RSRP(参考信号接收功率)和RSRQ(参考信号接收质量),降低了系统的切换失败率,同时减少了不必要的切换,但没有考虑用户运动方向的影响.综合加权考虑多种因素,如用户的移动方向以及小区资源的变化等对切换的影响等方面均有待深入开展研究. 相似文献
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提出了一种在协同多入多出(Co-MIMO,collaborative MIMO)系统中的自适应用户数选择算法.基站向调度器报告各个移动台从本基站接收到的信号、干扰及噪声功率,调度器据此计算各个基站支持用户数的最佳方案,反馈给相应的基站.自适应方案根据信道的变换灵活改变基站和移动台之间的从属关系,达到有效降低小区边缘用户的小区间干扰、优化小区边缘系统容量的目的.仿真结果证明了在发射端多用户预编码下自适应支持用户数选择算法相对于支持固定用户数的优势. 相似文献
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考虑LTE用户信噪比,借助物理资源块的服务能力推算小区负载的变化状态,提出的CTLB算法能够动态地根据每个小区的负载,自动计算需要进行用户转移的小区。引入均衡因子,使所有小区最终达到预先设定的收敛目标,从而有效利用网络资源。最后,通过MATLAB搭建了一个仿真平台,验证算法的收敛性能、过载用户数及小区吞吐量的变化情况。 相似文献
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对下一代移动通信系统的小区间动态干扰协调算法进行研究,通过分析干扰水平,负载状况,基站的调节能力以及用户的位置,通过负载因子变化来接纳控制,提高边缘用户的数据传输速度,保证小区用户的公平性。通过上行功率控制及接纳算法改进方案;同时对小区用户划分区域设定,提出了小区间干扰协调的改进算法(ICPF), 并进行系统仿真计算分析,结果表明和以往传统算法相比,系统性能得到有效改进,进一步提高了系统公平性并增加小区边缘用户的吞吐量。 相似文献
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Cell biasing is an effective solution for mobile user offloading in Heterogeneous Cellular Network (HetNet). Cell biasing modifies the user association criteria by incorporating Range Expansion Bias (REB) in traditional reference signal based user association technique. For sparse user distribution, REB for picocells does not offload users located outside RSRP Threshold Coverage Area. This is because the actual Reference Signal Received Power (RSRP) value for such users is lesser than the threshold RSRP value for successful communication. On the other hand, using a negative REB value for dense user distribution around picocells is not desirable because it leads to higher interference at users and high energy consumption at macrocells. In this paper, we suggest a unified framework for coverage optimization using spectrum slicing and transmit power spreading. Our proposed framework considers a combination of subchannel transmit power and REB which is based on the user distribution around picocells. Additionally, in order to protect the signal quality of macrocell users located close to picocells, we suggest location aware subchannel allocation technique. This technique maximizes the number of Interference Free subchannels for macrocell users. Obtained results show that our proposed framework can significantly improve the coverage and system blocking for HetNet. 相似文献
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为了解决超密集网络中用户在移动过程中由于小区间干扰和负载不均衡导致的用户服务质量下降的问题,本文研究了一种面向负载均衡的主动切换策略,设计了一种基于双门限的移动切换策略,包含小区内的切换与小区间的切换。通过优化小区内的切换门限,可以最小化系统总资源开销。通过优化小区间的切换门限,能够保证用户实时业务需求的同时均衡网络负载。通过预测用户未来大尺度信道信息,设计主动的双门限切换策略,可以有效降低切换延迟。仿真结果表明,与现有的切换策略相比,所提算法不仅提高了资源利用率,还降低了用户掉线概率与切换次数。 相似文献
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超密集网络(UDNs)拉近了终端与节点间的距离,使得网络频谱效率大幅度提高,扩展了系统容量,但是小区边缘用户的性能严重下降。合理规划的虚拟小区(VC)只能降低中等规模UDNs的干扰,而重叠基站下的用户的干扰需要协作用户簇的方法来解决。该文提出了一种干扰增量降低(IIR)的用户分簇算法,通过在簇间不断交换带来最大干扰的用户,最小化簇内的干扰和,最终最大化系统和速率。该算法在不提高K均值算法的复杂度的同时,不需要指定簇首,避免陷入局部最优。仿真结果表明,网络密集部署时,有效提高系统和速率,尤其是边缘用户的吞吐量。 相似文献
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In orthogonal frequency division multiple access(OFDMA) based femtocell networks,the co-tier interference among femto base stations(FBS) becomes important in multiuser and densely deployed environment.In order to mitigate the co-tier interference and enhance the system total throughput,this paper proposed a best effort spectrum allocation scheme based on the extension of graph theory.In the scheme,a controller was proposed to collect the channel state information(CSI)of all femtocell user equipments(FUEs) in a certain range.Then,the controller evaluated the signal-to-interference Ratio(SIR) of each FUE and determined the set of its interference neighbors.By calculating the received power matrix(RPM) among FUEs and building interference graph matrix(IGM),different spectrum resource blocks(RBs) were assigned to the users with interference relation,while users without interference relation shared the same RBs,which could increase the spectrum efficiency.Simulation results show that the proposed algorithm can significantly improve the RB usage efficiency compared with the basic graph coloring theory,and more than 80% improvement can be acquired in dense deployment scenario.Besides,the throughput of both cell edge macro user equipments(MUEs) and cell edge FUEs is guaranteed on the premise of low interference. 相似文献
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Adaptive cell sectorization for CDMA systems 总被引:3,自引:0,他引:3
Given the user distribution in a cell, we investigate the two problems of how to appropriately sectorize the cell such that we minimize the total received power and the total transmit power of all the users, while giving each user acceptable quality of service in both cases. For the received power optimization problem, we show that the optimum arrangement equalizes the number of users in each sector. The transmit power optimization is formulated as a graph partitioning problem that is polynomially solvable. We provide an algorithm that finds the best sectorization assignment as well as the optimal transmit powers for all the users. The computational complexity of the algorithm is polynomial in the number of users and sectors. For both the received power optimization and the transmit power optimization, under nonuniform traffic conditions, we show that the optimum arrangement can be quite different from uniform cell sectorization (equal width sectors). We also formulate and solve the transmit power optimization and cell sectorization problem in a multicell scenario that would improve the capacity of a hot spot in the network. We observe that, with adaptive sectorization, where the sector boundaries are determined in response to users' locations, received and transmit power savings are achieved, and the number of users served by the system (system capacity) is increased compared to uniform sectorization of the cell 相似文献