HetNets Under Decoupled Uplink and Downlink Access with UE Random Discontinuous Transmission: Local Delay and Energy Efficiency

Due to the limited uplink capability in heterogeneousnetworks (HetNets), the decoupled uplinkand downlink access (DUDA) mode has recently beenproposed to improve the uplink performance. In thispaper, the random discontinuous transmission (DTX)at user equipment (UE) is adopted to reduce the interferencecorrelation across different time slots. By utilizingstochastic geometry, we analytically derive themean local delay and energy efficiency (EE) of an uplinkHetNet with UE random DTX scheme under theDUDA mode. These expressions are further approximatedas closed forms under reasonable assumptions.Our results reveal that under the DUDA mode, there isan optimal EE with respect to mute probability underthe finite local delay constraint. In addition, with thesame finite mean local delay as under the coupled uplinkand downlink access (CUDA) mode, the HetNetsunder the DUDA mode can achieve a higher EE witha lower mute probability.

Cross-Tier Interference Mitigation in 3D HetNets for LTE and Wi-Fi Access

Due to the unprecedented rate of transformation in thefield of wireless communication industry,there is a need to prioritise the coverage,network power and throughput as preconditions.In Heterogeneous Networks(HetNets)the low power node inclusion like Femto and Pico cells creates a network of Multi-Tier(M-Tier)which is regarded as the most significant strategy for enhancing the coverage,throughput,4G Long Term Evolution(LTE)ability.This work mainly focuses on M-Tier 3D Heterogeneous Networks Energy Efficiency(EE)based Carrier Aggregation(CA)scheme for streaming real-time huge data like images.Atfirst,M-Tier 3D HetNets scheme was made for investigating Signal to Noise Interference Ratio(SNIR)on assessing the collective Pico-tier and Femto-tier interference.Next,the scheme of channel allocation is scrutinised so as to esti-mate throughput from the multiple tiers.Additionally,with the use of CA technique,the problem of energy efficiency for M-Tier 3D Heterogeneous Network(HetNet)in relation to energy metrics and throughput was evaluated with the use of LTE and Wireless Fidelity(Wi-Fi)coexistence.The simulation is carried out in a MATLAB setting,and the outcomes reveal a huge impact on EE.The simulation is carried in terms of EE,transmission time,throughput,packet success rate,convergence probability,and coverage region.The analysis from simu-lation shows that on improving the output of the device,interference among small cell base stations is reduced on increasing EE.The outcomes attained aid in the effective creation of M-Tier 3D HetNets for enhancing EE by employing Multi-Stream Carrier Aggregation(MSCA)in HetNets.

Energy efficiency based joint cell selection and power allocation scheme for HetNets

Heterogeneous networks （HetNets） composed of overlapped cells with different sizes are expected to improve the transmission performance of data service significantly. User equipments （UEs） in the overlapped area of multiple cells might be able to access various base stations （BSs） of the cells, resulting in various transmission performances due to cell heterogeneity. Hence, designing optimal cell selection scheme is of particular importance for it may affect user quality of service （QoS） and network performance significantly. In this paper, we jointly consider cell selection and transmit power allocation problem in a HetNet consisting of multiple cells. For a single UE case, we formulate the energy efficiency of the UE, and propose an energy efficient optimization scheme which selects the optimal cell corresponding to the maximum energy efficiency of the UE. The problem is then extended to multiple UEs case. To achieve joint performance optimization of all the UEs, we formulate an optimization problem with the objective of maximizing the sum energy efficiency of UEs subject to QoS and power constraints. The formulated nonlinear fractional optimization problem is equivalently transformed into two subproblems, i.e., power allocation subproblem of each UE-eell pair, and cell selection subproblem of UEs. The two subproblems are solved respectively through applying Lagrange dual method and Kuhn-Munkres （K- M） algorithm. Numerical results demonstrate the efficiency of the proposed algorithm.

A Markov Based Performance Analysis of Handover and Load Balancing in HetNets

LTE heterogeneous networks (HetNets) is becoming a popular topic since it was first developed in 3GPP Release 10. HetNets has the advantage to assemble various cell networks and enhance users’ Quality of Service (QoS) within the system. However, its development is still constrained by two main issues: 1) Load imbalance caused by different transmission powers for various tiers, and 2) The unbalanced transmission power may also increase unnecessary handover rate. In order to solve the first issue, Cell range expansion (CRE) can be applied in the system, which will benefit lower-tier cell during user association phase;CRE, Hysteresis Margin (HM) and Time-to-Trigger (TTT) will be utilized to bound UE within lower tier network of HetNets and therefore solve the second issue. On the other hand, the relationship of these parameters may be complicated and even reduce QoS if they are chosen incorrectly. This paper will evaluate the advantage and disadvantage of all three parameters and propose a Markov Chain Process (MCP) based method to find optimal HM, CRE and TTT values. And then, the simulation is taken and the optimal combination for our scenario is obtained to be 1 dB, 6 dB and 60 ms respectively. First contribution of this paper is to map the HetNets handover process into MCP and all the phases of handover can be calculated and analysed in probability way, so that further prediction and simulation can be realised. Second contribution is to establish a mathematical method to model the relationship of HM, CRE and TTT in HetNets, therefore the coordination of these three important parameters is achieved to obtain system optimization.

An enhanced almost blank sub-frame management for efficient elCIC in non-uniform HetNets

A new enhanced inter-cell interference coordination （elCIC） is adopted for managing almost blank sub-frame （ABS）,which jointly exploits the time, frequency and power dimensions to improve the resource utilization. In particular, a non-uniform two tier heterogeneous network （ HetNet） is considered, where the pico cells are located close to the macro cell and the number of users in each pico cell is different. To alleviate the interference caused by the co-channeldeployment,the macro cells employ low power ABS （LP- ABS）, and the resource blocks （RBs） are divided into twoparts during an ABS. One is exclusively reserved for macro cell users ad the other is reserved for pico cell users. Themacro cells are allowed to use different percentages of RBs and different powers for their own transmission during the LP- ABS. The user association,resource allocation,ABS proportion,the frequency band partition parameter and the transmission power of macro cells are considered, aiming at maximizing the proportional fairness utility of the system. An iterative algorithm is also proposed and simulation results demonstrate that the proposed algorithm can improve both the system throughput and user fairness compared with the existing schemes.

5G超密集异构网络双连接技术架构设计

双连接(Dual Connectivity,DC)技术是一种创新型技术,可以满足5G超密集异构网络(Heterogeneous Network,HetNet)日益增长的高数据速率传输需求。在5G超密集HetNet中,DC切换是对传统移动网络切换的进一步优化和发展。因此,以DC技术的一般概念为基础,设计了5G非独立接入(Non-Standalone Access,NSA)架构和独立接入(Standalone Access,SA)架构。同时,为确保5G超密集HetNet业务的连续性,避免小蜂窝之间频繁切换和乒乓效应的发生,设计了基于DC的切换程序。

Modular handover algorithm for 5G HetNets with comprehensive load index

Most existing handover decision system （HDS） designs are monolithic, resulting in high computational cost and unbalance of overall network. A novel modular handover algorithm with a comprehensive load index for the 5th generation （5G） heterogeneous networks （HetNets） is proposed. In this paper, the handover parameters, serving as the basis for handover, are classified into network＇s quality of service （QoS） module, user preference （UP） module and degree of satisfaction （DS） module according to the new modular HDS design. To optimize switching process, the comprehensive network load index is deduced by using triangle module fusion operator. With respect to the existing handover algorithm, the simulation results indicate that the proposed algorithm can reduce the handover frequency and maintain user satisfaction at a higher level. Meanwhile, due to its block calculation, it can bring about 1.4 s execution time improvement.

Caching modeling and energy analyzing of cell-free wireless heterogeneous networks with beta Ginibre point process

Cell-free Wireless Heterogeneous Networks(HetNets)have emerged as a technological alternative for conventional cellular networks.In this paper,we study the spatially correlative caching strategy,the energy analysis,and the impact of parameter β on the total energy cost of the cell-free wireless HetNets with Access Points distributed by Beta Ginibre Point Process(β-GPP).We derive the approximate expression of Successful Delivery Probability(SDP)based on the Signal-to-Interference-plus-Noise Ratio coverage model.From both analytical and simulation results,it is shown that the proposed caching model based on β-GPP placement,which jointly takes into account path loss,fading,and interference,can closely simulate the caching performance of the cell-free HetNets in terms of SDP.By guaranteeing the outage probability constraints,the analytical expression of the uplink energy cost is also derived.Another conclusion is that with AP locations modeled by β-GPP,the power consumption is not sensitive to β,but is sensitive to the dimension of the kernel function;hence β is less restrictive,and only the truncation of the Ginibre kernel has to be appropriately modified.These findings are new compared with the existing literature where the nodes are commonly assumed to be of Poisson Point Process,Matern Hard-Core Process,or Poisson Cluster Process deployment in cell-free systems.

LTE的新技术展望

为应对移动互联网带来的海量数据流量的承载需求,4G网络亟需引入异构网的新型组网形态,并打造多网络智能协同融合的移动智能管道,争取首先在组网架构上有一个新突破。本文基于3GPP标准化进程,对LTE分层组网的HetNet、小区干扰协调以及LTE与WLAN智能协同的SaMOG、ANDSF等新技术进行展望。

Joint Spectrum Partition and Performance Analysis of Full-Duplex D2D Communications in Multi-Tier Wireless Networks

Full-duplex(FD)has been recognized as a promising technology for future 5G networks to improve the spectrum efficiency.However,the biggest practical impediments of realizing full-duplex communications are the presence of self-interference,especially in complex cellular networks.With the current development of self-interference cancellation techniques,full-duplex has been considered to be more suitable for device-to-device(D2D)and small cell communications which have small transmission range and low transmit power.In this paper,we consider the full-duplex D2D communications in multi-tier wireless networks and present an analytical model which jointly considers mode selection,resource allocation,and power control.Specifically,we consider a distance based mode selection scheme.The performance analysis of different D2D communications modes are performed based on stochastic geometry,and tractable analytical solutions are obtained.Then we investigate the optimal resource partitions between dedicated D2D mode and cellular mode.Numerical results validate the theoretical anlaysis and indicate that with appropriate proportions of users operated in different transmission modes and optimal partitioning of spectrum,the performance gain of FD-D2D communication can be achieved.

HetNet无线网络架构的研究

近年来,随着智能终端的日益丰富,移动互联网迅猛发展,无线数据流量和信令数量对网络的冲击前所未有,这使得"频谱"和"站点"从未像现在这样成为左右无线网络未来发展的关键要素。站点密度触碰到无法超越的极限。经过多年的建设,宏站建设密度已经非常大,一些发达地区密集城区的站间距甚至小于米。尽管如此,由于城市环境复杂、业务量大,网络仍面临容量压力和深度覆盖盲区。然而,受邻区干扰机制所限,继续提升宏站密度,并不是解决这些问题的有效办法。解码无线网络建设新模式扩展宏蜂窝层,提升单站吞吐量以保障移动网络连续覆盖,能有效解决现有问题的HetNet立体分层组网体系,正是本文研究的主要内容。

5G异构组网技术工程实施探讨

针对5G超密集异构网络组网技术进行深入研究,摸索出适合本地条件5G超密集异构网络组网模式,以便为将来的5G网络全面部署和推广应用打下坚实的基础。研究内容包括:超密集网络部署研究、异构站点选择探索、站点获取经验摸索、异构网选择原则、能耗效率控制技术、异构协同技术、回传链路技术研究、资源优化配置研究等。对超密集网络、站点选择、站点获取、异构网选择、能耗效率、异构协同、回传链路等问题进行深入分析,并根据工程建设实际情况对这些问题提出具有可行性的建议。

Clustering-based adaptive low-power subframe configuration with load-aware offsetting in dense heterogeneous networks

Heterogeneous Networks(HetNets)and cell densification represent promising solutions for the surging data traffic demand in wireless networks.In dense HetNets,user traffic is steered toward the Low-Power Node(LPN)when possible to enhance the user throughput and system capacity by increasing the area spectral efficiency.However,because of the transmit power differences in different tiers of HetNets and irregular service demand,a load imbalance typically exists among different serving nodes.To offload more traffic to LPNs and coordinate the Inter-Cell Interference(ICI),Third-Generation Partnership Project(3GPP)has facilitated the development of the Cell Range Expansion(CRE),enhanced Inter-Cell Interference Coordination(eICIC)and Further enhanced ICIC(FeICIC).In this paper,we develop a cell clustering-based load-aware offsetting and an adaptive Low-Power Subframe(LPS)approach.Our solution allows the separation of User Association(UA)functions at the User Equipment(UE)and network server such that users can make a simple cell-selection decision similar to that in the maximum Received Signal Strength(max-RSS)based UA scheme,where the network server computes the load-aware offsetting and required LPS periods based on the load conditions of the system.The proposed solution is evaluated using system-level simulations wherein the results correspond to performance changes in different service regions.Results show that our method effectively solves the offloading and interference coordination problems in dense HetNets.

城市无线立体异构网络部署分析

随着城市的不断发展,各大运营商2G、3G、LTE等无线网络的发展,无线传播环境日益复杂,针对通信行业内在建设GSM网、TDS网、WLAN网等多层网络方面,尤其是在高校、高端小区、商务区等特殊场景,存在很多的发展困惑,譬如各种场景下多层网络如何组网、如何归类、如何识别不同的业务类型,如何划定业务发展模型、如何更有效的将数据业务分流到相对廉价的网络制式上等等。面对此类纷繁复杂的现实情况,如何更有效地在城区部署无线网络是本文解决的主要问题。

异构网络的构建与小基站的测试需求

通过介绍异构网,引入small cell这一概念,着重论述了small cell在未来LTE网络中的重要性以及由此带来的新挑战。通过对比3GPP标准中相关宏基站与small cell在射频测试当中不同指标的定义,阐述了在测试small cell射频指标性能时所面临的挑战和解决方案。

TD-LTE深度覆盖方案研究

本文对TD-LTE深度覆盖的场景要求进行了全面分析,给出了不同场景下的解决方案。并对3GPP R10协议中的HetNet深度覆盖方案进行了研究,对其需要注意的关键问题进行了全面的分析,为中国移动深度覆盖方案提供了参考。

HetNet中基于上行CoMP的动态多小区接入算法

提出了HetNet中基于上行CoMP的动态多小区接入算法(UCDS),动态选择协作基站,利用CoMP机制,改善小区边缘用户的上行传输性能。进一步地,提出了基于二次判决的协作小区选择算法(DJCS),以减少参与协作的基站数,降低协作复杂度并节省基站端资源。仿真结果表明,UCDS算法能显著提高边缘用户的平均吞吐率和传输能效,而DJCS算法在保证用户性能的情况下,降低了基站端的能耗。

Delay-Based User Association in Heterogeneous Networks with Backhaul

The Internet of things(IoT) as an important application of future communication networks puts a high premium on delay issues. Thus when Io T applications meet heterogeneous networks(HetNets) where macro cells are overlaid with small cells, some traditional problems need rethinking. In this paper, we investigate the delay-addressed association problem in two-tier Het Nets considering different backhaul technologies. Specifically, millimeter wave and fiber links are used to provide high-capacity backhaul for small cells. We first formulate the user association problem to minimize the total delay which depends on the probability of successful transmission, the number of user terminals(UTs), and the number of base stations(BSs). And then two algorithms for active mode and mixed mode are proposed to minimize the network delay. Simulation results show that algorithms based on mutual selection between UTs and BSs have better performance than those based on distance. And algorithms for mixed modes have less delay than those for active mode when the number of BSs is large enough, compared to the number of UTs.

Optimal Power Allocation for Heterogeneous Network Capacity Maximization

We investigate the optimal joint power allocation in Heterogeneous Networks （HetNets） to maximise its capacity. Consider- ing frequency reuse in the network, we study two power-constraint cases, i.e., per-cell po- wer constraint case and per-tier power con- straint case. We formulate the capacity maxi- mization problem by allowing each subcarrier of Marco eNodeB （MeNB） to be shared by users from multiple Picos. We mathematically demonstrate that the optimal power allocation in the per-cell power constraint case has a re- markably simple nature： each Pico transmits to its user with maximum power, while MeNB either selects only one user to jointly transmit with maximum power or does not transmit to any user. In the per-tier power constraint case, the difference is that the power allocation be- tween two Picos takes the form of water-fill- ing. Numerical results verify that our proposed schemes outperform the conventional interfe- rence coordination schemes.

A blockchain-empowered AAA scheme in the large-scale HetNet

A Large-Scale Heterogeneous Network(LS-HetNet)integrates different networks into one uniform network system to provide seamless one-world network coverage.In LS-HetNet,various devices use different technologies to access heterogeneous networks and generate a large amount of data.For dealing with a large number of access requirements,these data are usually stored in the HetNet Domain Management Server(HDMS)of the current domain,and HDMS uses a centralized Authentication/Authorization/Auditing(AAA)scheme to protect the data.However,this centralized method easily causes the data to be modified or disclosed.To address this issue,we propose a blockchain-empowered AAA scheme for accessing data of LS-HetNet.Firstly,the account address of the blockchain is used as the identity authentication,and the access control permission of data is redesigned and stored on the blockchain,then processes of AAA are redefined.Finally,the experimental model on Ethereum private chain is built,and the results show that the scheme is not only secure but also decentral,without tampering and trustworthiness.