软分数频率复用在4G通信系统中应用

针对4G移动通信系统提出的提高频谱利用率、同频组网的需求，文章从频率复用问题入手，提出了一种软分数频率复用方案。软分数频率复用方案包括3种表现形式，在实际应用中，可以根据物理层链路增益选择适当的表现形式。文章以第2种表现形式为例介绍了采用该方案的频率复用方法。研究表明，使用软分数频率复用方案，系统的频率复用系数可以达到1／3～1。软分数频率复用方案解决了同频组网问题，并已经在上海4G实验网中得到了良好的应用。     

同频分布式FuTURE TDD第四代移动通信系统

针对第四代（4G）移动通信系统的基本需求，探讨了同频分布式FuTURE 4G TDD试验系统中的链路技术和同频分布式组网方案，给出了全链路方案设计参数以及基于可拓集合的软分数频率复用同频分布式组网方案．最后，结合外场测试环境，给出了现场实测误块率以及频率复用系数。     

OFDMA系统静态软频率复用技术研究

在OFDMA系统中,小区间同频干扰是主要干扰。在B3G/4G系统中,为了减少小区间干扰,静态软频率复用技术已得到了广泛的应用。介绍了2种静态软频率复用方案:经典软频率复用和基于功率重用的软频率复用。在此基础上,详细研究了使用改进型比例公平调度算法的功率重用软频率复用系统。通过仿真,分析并证实了静态软频率复用技术可对边缘用户吞吐量带来极大提升,同时给出并验证了系统中改进型比例公平调度器的最佳配置参数。     

TD-SCDMA系统频率规划方法分析

首先介绍了TD-SCDMA系统组网方式，接着重点分析比较了三种异频组网方案．然后详细阐述了其他组网策略的三个组网方案．最后对不同组网方式和组网方案进行了归纳，本文旨在找到一条兼顾系统指标、容量及发展的可行方法．建议在TD-SCDMA网络大规模建设初期．业务信道可采用异频组网方式和采用173／3频率复用方式。     

TD-SCDMA室内外频率复用组网解决方案

文章从室内外基站相互干扰特性出发,分析7TD—SCDMA室内外同频组网的干扰情况。并提出了根据干扰情况进行频率分配和无线资源调整的频率复用组网解决方案,最后研究该项技术在实际网络的应用效果,并提出部署建议。     

LTE-A中继网络中干扰协调算法分析

在LTE-Advanced网络中,引入中继(Relay)技术解决小区边缘用户的通信质量较差问题,但在这种中继节点与基站的同频组网的情况下,存在严重的小区内干扰,仅增大频率复用数量,会使信道质量降低,同时增加了小区内的干扰,所以设计一种好的中继网络中干扰协调算法十分重要。文章拟研究基于部分频率复用的小区内干扰协调技术,从部分频率复用的角度,针对下行链路,通过基于MATLAB的LTE系统及仿真平台测试不同的频率复用系数,从仿真显示结果找出一个合适的频率系数,使得干扰最小,频谱利用率最高。     

B3G/4G中的软频率复用方案及算法研究

文章首先简要介绍了传统的复用方案和具有代表性的几种小区间干扰协调方案,然后主要介绍了软频率复用方案的原理和性能,最后提出了子载波资源单向分配、子载波资源随机分配和子载波资源双向分配等软频率复用方案及具体实现算法。通过仿真得出结论,子载波资源双向分配方案在业务量不高情况下,具有显著优势,并且实现复杂度低。     

抑制LTE系统小区间干扰的软频率复用改进方案

为提高系统性能,LTE系统可通过频率复用因子（Frequency Reuse Factor,FRF）为 3的软频率复用（Soft Frequency Reuse,SFR）方案来有效抑制小区间的同频干扰,但在小 区峰值速率和系统容量方面仍有改善空间,由此介绍一种FRF为7的SFR方案,并结合与之相 适应的资源调度策略,可较大地提高小区边缘用户的峰值速率,使系统容量得以提升。     

基于位置的无线通信系统资源管理方案研究

首先提出一种基于位置的ICIC(小区间干扰协调)方案和一种基于位置的辅助中继选择方案。对前一种方案,分析方案中的硬频率复用、部分频率复用和软频率复用三种频率复用策略的原理和优缺点;对后一种方案,通过获取无线通信系统中MT(移动终端)的位置、路径损耗和SNR(信噪比),采用传播模型对BER(比特误码率)做出估计。     

跳频技术与1×3频率复用技术的结合

简要介绍了跳频技术的原理以及现在普遍采用的4×3频率复用技术。针对现实需要解决的网络容量和质量的问题 ,提出在4×3频率复用的基础上运用1×3频率复用技术与跳频技术相结合 ,并列举了一些具体实施的抗干扰措施和思路     

多小区OFDMA系统中分数频率复用方法的优化分析

在以OFDMA为基本多址方式的第四代移动通信系统中,频率复用作为提高系统性能的有效方法受到了广泛的关注,特别是分数频率复用和软频率复用。然而,如何进一步优化基于这些频率复用方法的OFDMA系统还有待研究。本文分析了多小区OFDMA系统负载和频率集合分配比例对小区总吞吐量和小区边缘用户数据速率的影响。同时,给出了在保证小区边缘用户服务质量的条件下,使小区总吞吐量最优的小区中心频率分配比例,并用仿真进行验证。仿真结果还表明了,随着分配比例的增大,小区总吞吐量先增大后减小。     

室内密集型家庭基站网中自适应软频率复用技术

Femtocell networks have emerged as a key technology in residential, office building or hotspot deployments that can significantly fulfill high data demands in order to offload indoor traffic from outdoor macro cells. However, as one of the major challenges, inter-femtocell interference gets worse in 3D in-building scenarios because of the presence of numerous interfering sources and then needs to be considered in the early network planning phase. The indoor network planning and optimization tool suite, Ranplan Small- cell?, makes accurate prediction of indoor wireless RF signal propagation possible to guide actual indoor femtocell deployments. In this paper, a new adaptive soft frequency reuse scheme in the dense femtocell networks is proposed, where multiple dense femtocells are classified into a number of groups accord-ing to the dominant interference strength to others, then the minimum subchannels with different frequency reuse factors for these groups are determined and transmit powers of the grouping sub-channels are adaptively ad-justed based on the strength to mitigate the mutual interference. Simulation results show the proposed scheme yields great performance gains in terms of the spectrum efficiency relative to the legacy soft frequency reuse and universal frequency re-use.     

A universal frequency reuse scheme in LTE‐A heterogeneous networks

Effective inter‐cell interference mitigation has been extensively studied because of its outstanding cell‐edge signal quality improvement capability. Conventional static inter‐cell interference coordination strategies, including fractional frequency reuse and soft frequency reuse, have received much attention owing to their effectiveness in mitigating interference and low complexity in implementation. However, they are less effective when dealing with dense uneven traffic distributions and dynamic traffic demands and thus incur low spectrum utilization in some cells and spectrum shortage in others. This paper proposes a universal frequency reuse scheme in a two‐layer Long Term Evolution‐Advanced heterogeneous network to ensure good throughput for all user equipment (UE), especially UEs at cell edge. The proposed scheme allows each cell to use all the spectrum resources, limited by an orderly regulation of all sub‐bands. This scheme minimizes the potential occurrence probability of inter‐cell co‐sub‐band interference through an intra‐cell sub‐band resource management. Furthermore, a graph‐theoretic based sub‐band allocation algorithm is developed to optimize UE throughput performance, especially for the cell‐edge low signal to interference noise ratio UEs. A comprehensive performance comparison among different frequency reuse schemes is conducted by considering performance metrics, including cell‐edge throughput, average throughput, and signal to interference noise ratio cumulative distribution function. Simulation result shows that the universal frequency reuse scheme outperforms other two schemes significantly. Copyright © 2016 John Wiley & Sons, Ltd.     

一种基于OFDMA系统的频率复用方法

频率复用作为提高小区边缘用户性能的有效方式已被广为研究。然而,如何在提高小区边缘用户性能的同时,使频谱利用率得到有效提高仍是一个有待解决的问题。在以正交频分多址(OFDMA)为基本多址方式的第4代(4G)系统中该问题尤为突出。为此,该文提出了一种OFDMA系统中的频率复用方法,通过抑制小区间干扰提高小区边缘用户性能;同时,根据小区中心与小区边缘通信环境的差异,分别对其实施不同的频率复用策略使频率复用系数接近于1以提高频谱利用率。仿真结果表明,与未经过频率规划的全频率复用相比,该文提出的频率复用方法提高了系统吞吐量并显著改善了小区边缘用户性能。     

A capacity degradation model under interferences for sectorized cellular networks with fractional frequency reuse

This paper presents a capacity degradation model under interferences for sectorized cellular networks with fractional frequency reuse. In a sectorized fractional frequency reuse network, allocated bandwidth consists of a number of frequency partitions. To avoid intra‐cell interferences, each frequency partition is then assigned to two different groups, the super group (Sup‐G) and the regular group. However, because a Sup‐G in a cell employs the same frequency partition as the other Sup‐Gs in the neighboring cells, inter‐cell interferences may become serious when the radius of the Sup‐G is largely increased. In the worse case, the largely increasing inter‐cell interferences will eventually degrade the overall system capacity. Additionally, different density distributions of mobile stations may have different levels of impact on the capacity degradation. In this paper, both folded normal distribution and uniform distribution are considered in building the capacity degradation model. Numerical simulations show that by carefully adjusting the ratio between the radius of the Sup‐G and the radius of a cell, (i) an mobile station could receive the same capacity no matter where it is residing, and (ii) the maximum system capacity can be therefore achieved. Copyright © 2013 John Wiley & Sons, Ltd.     

Downlink Transmit Power Allocation in Soft Fractional Frequency Reuse Systems

Downlink transmit power allocation schemes are proposed for soft fractional frequency reuse (FFR) in loose and tightly coordinated systems. The transmit powers are allocated so that the loss of spectral efficiency from the soft FFR is minimized, and the required cell edge user throughput is guaranteed. The effect of the soft FFR on spectral efficiency is evaluated depending on the power allocation schemes and the number of subbands. Results show that the loss of spectral efficiency from the soft FFR can be reduced by configuring an appropriate number of subbands in the loosely coordinated systems. In tightly coordinated systems, results show that the loss of spectral efficiency can be minimized regardless of the number of subbands due to its fast coordination.     

Multi-beam cooperative frequency reuse for coordinated multi-point transmission

Coordinated multi-point (CoMP) joint transmission is considered in the 3rd generation partnership project (3GPP) long term evolution (LTE)-advanced as a key technique to mitigate inter-cell interference and improve the cell-edge performance. To effectively apply CoMP joint transmission, efficient frequency reuse schemes need to be designed to support resource management cooperation among coordinated cells. However, most of the existing frequency reuse schemes are not suitable for CoMP systems due to not considering multi-point joint transmission scenarios in their frequency reuse rules. In addition, the restrictions of frequency resources in those schemes result in a high blocking probability. To solve the above two problems, a multi-beam cooperative frequency reuse (MBCFR) scheme is proposed in this paper, which reuses all the available frequency resources in each sector and supports multi-beam joint transmission for cell-edge users. Besides, the blocking probability is proved to be efficiently reduced. Moreover, a frequency-segment-sequence based MBCFR scheme is introduced to further reduce the inter-cell interference. System level simulations demonstrate that the proposed scheme results in higher cell-edge average throughput and cell-average throughput with lower blocking probability.     

Performance of power control in inter-cell interference coordination for frequency reuse

To mitigate inter-cell interference in 3G evolution systems,a novel inter-cell interference coordination scheme called soft fractional frequency reuse is proposed in this article,which enables to improve the data rate in cell-edge.On this basis,an inter-cell power control is presented for the inter-cell interference coordination,and the inter-cell balanced signal to interference plus noise ratio(SINR) among users is established for power allocation,which enables mitigation of inter-cell interference.Especia...