绿色蜂窝网络的频谱效率与能效函数

为了给绿色蜂窝网络的研究和设计提供一个基本的基准或判断依据,对存在多小区干扰和越区切换情况下蜂窝网络的网络传输能力(网络频谱效率)和能量效率函数(能效函数)进行了研究,揭示了蜂窝网络的功率开销与频谱效率之间的关系。首先,给出了蜂窝网络能效函数的定义,并在此基础上提出了小区干扰深度和越区切换的动力学模型,进而论证了存在多小区干扰和越区切换情况下的蜂窝网络频谱效率,并推证了数学表达式。最后,求解了蜂窝网络的能效函数,讨论了相关参数对它的影响和数值结果分析,为绿色蜂窝网络的研究和设计,提供了有益的分析依据和基础。     

生活小区的深度覆盖和容量解决方案

本文针对生活小区的无线环境，研究如何低成本解决小区室内环境的覆盖和网络话务吸收等课题，比较宏蜂窝和微蜂窝方案，并提出了微蜂窝解决措施。     

蜂窝小区中基站天线最佳覆盖的探讨

基站天线是移动通信网络的关键部件,它不仅提供了移动台和基站之间的物理链接,同时也是频率复用、分集接收、优化覆盖等移动通信技术应用中的重要设备。在移动通信系统中,信号覆盖的效果是衡量这个系统的重要指标。为了满足不同的场景需求,对于移动通信信号的最佳覆盖进行研究具有重要意义。本文主要探讨影响网络覆盖的各种因素,对天线参数进行调整,以达到最佳的覆盖效果。     

生活小区的深度覆盖和容量解决方案

本文重点针对生活小区的无线环境，研究如何低成本地解决小区室内环境的覆盖和网络话务吸收等课题．并提出了微蜂窝解决措施。     

移动通信网络小区覆盖的室内外协同解决方案

为了有效解决大型住宅小区的覆盖问题，文章介绍了一种室内外协同覆盖的方法，阐述了室外天线的设计原则和室内分布系统补充覆盖要考虑的两个方面，最后给出了室内外协同覆盖的案例分析。     

基于服务覆盖的无蜂窝边缘智能网络部署方法

为实现未来网络绿色低碳发展,以精准的按需服务提高网络运营和部署效率,将服务覆盖作为网络覆盖能力的新度量。深入挖掘无蜂窝网络部署灵活的优势,可以使每个覆盖单元达到最佳服务覆盖,从而实现系统性能的差异化优化。结合无蜂窝边缘智能网络的通信链路质量对移动边缘计算（MEC）服务器计算和下载的时延、卸载概率的影响,采用连续凸逼近算法,引入松弛变量和辅助变量将接入点（AP）和MEC联合部署混合整数非线性规划问题转化为连续的凸优化问题进行求解。仿真结果证明,基于服务覆盖的网络部署方法提升了现有网络能量效率,并显著减少用户的计算时延和系统的能耗。     

从小区覆盖和无线干扰看网络优化

从当前模拟移动电话网络普遍存在的话务不均衡和无线干扰出发 ,提出小区有效覆盖区域概念及其与话务均衡的关系 ,阐述了无线干扰门限值对话音质量和系统资源的影响 ,最后还介绍了珠海TACS网的优化实例。     

实现小区深度覆盖选择美化天线的方案探讨

文章分析了小区深度覆盖在实际建设中存在的问题,并针对这些问题对目前采用常规方法建设小区覆盖的效果进行分析对比,提出了在小区深度覆盖中不同楼宇类型应采用不同技术参数的天线方案。     

高层住宅小区LTE网络深度覆盖方案分析

本文结合实际经验,通过对高层住宅小区覆盖问题的分析,系统性地提出一套高层住宅小区LTE深度覆盖解决方案,为下一步LTE网络在高层住宅小区场景中的建设和优化提供一种借鉴。     

中继蜂窝网络中小区间和小区内的资源分割

文章提出了一种应用于固定中继蜂窝网络中基于复用分割的小区间频谱分配框架,通过引入有效复用因子这一指标来优化小区内基站和中继之间的资源分割,并比较了不同的链路带宽分配方案对系统性能的影响。理论分析和仿真结果显示,该方案可以在保证小区边缘用户的吞吐量的同时提高小区容量。     

Performance analysis of hexagonal cellular networks in fading channels

This paper analyzes the location‐dependent performance metrics of coverage probability and spectral efficiency in hexagonal cellular networks under Rayleigh fading with a general distribution for shadowing and also including two special cases of no shadowing and lognormal shadowing. The effects of system parameters such as frequency reuse factor, transmission probability of base stations, and signal‐to‐interference‐plus‐noise ratio gap from Shannon capacity are accurately characterized. The proposed approach is applied to fractional frequency reuse (FFR) scheme where the impact of FFR on spectral efficiency is evaluated. Numerical results show that (i) in a lognormal‐shadowed Rayleigh fading channel with the shadowing standard deviation of 12 dB, the cell area wide spectral efficiency is degraded by approximately 40% compared with when there is Rayleigh fading without shadowing; (ii) the improvement in spectral efficiency achieved by FFR over the universal frequency reuse increases as the transmission probability increases and the shadowing becomes less severe; and (iii) in Rayleigh fading without shadowing environment where all the base stations are actively transmitting, FFR achieves approximately 20% improvement in spectral efficiency in the cell edge area. Interestingly, this improvement increases to about 30% if a 3‐dB signal‐to‐interference‐plus‐noise ratio gap from Shannon capacity is further accounted. Copyright © 2015 JohnWiley & Sons     

蜂窝物联网核心网目标架构演进探讨

物联网存在面向2G、4G、窄带物联网（narrow band Internet of things,NB-Io T）的传统专用核心网以及面向5G的toB物联网核心网。随着网络的进一步云化演进，为简化网络、增强能力、提升效益、方便运维，需要明确面向未来的物联网核心网目标架构。基于现网存在的问题，结合网络演进驱动力，对物联网网络演进目标架构、演进策略以及业务解决方案进行了分析和探讨，以此为运营商物联网规划建设提供参考。     

以PCB为干扰源的带孔机箱电磁辐射特性仿真研究

对电子设备进行电磁辐射特性的研究,不仅要考虑机箱表面孔缝的电磁泄露,更要考虑机箱内部干扰源的电磁辐射特性.本文提出一种将PCB的电磁辐射能量导入机箱内部作为干扰源的方法,用于计算电子设备的整机电磁辐射特性,并与耦合微带线作为内部干扰源的方法进行对比.基于本文提出的将PCB作为干扰源的方法,研究了开孔尺寸、开孔类型、开孔位置对电子设备电磁辐射特性的影响,所总结的规律可为电子设备的工程设计提供一定参考标准.     

Performance analysis of the forward link cdma2000 1xEV‐DO evolution for multirate services in cellular wireless system

In this paper, we propose a combined analytical and simulation framework for performance evaluation of the forward link in the cdma2000 evolution for data only (1xEV‐DO) cellular systems with throughput and spectral efficiency being used as performance metrics. A closed form expression for the aggregate average throughput is derived in terms of system‐dependent parameters and a discrete random process that reflects the stochastic behavior of the transmission channel. The random process is expressed in terms of the cumulative distribution function (CDF) of the users signal‐to‐interference‐plus‐noise ratio (SINR). Quantitative results for throughput and spectral efficiency are presented for a variety of users distribution models, base station antenna types and frequency reuse factors for the cases of sectorized and non‐sectorized cells. Furthermore, we study the impact of the cell radius on the system performance. Copyright © 2006 John Wiley & Sons, Ltd.     

Performance analysis of load balancing in OFDMA cellular networks with inter‐cell relay

To balance and improve the resource utilization of the orthogonal frequency division multiple access (OFDMA) cellular networks, we switch parts of the edge users in overloaded cell to the adjacent light‐loaded cells by using the inter‐cell relay. The efficiency of traditional load balancing method based on the cell switching is low and in some cases, will occur the collision load problem. In this paper, we propose a new load balancing scheme based on inter‐cell relay in downlink OFDMA cellular networks. Besides, we put forward a new spectrum division scheme to reduce interference and improve spectrum efficiency. According to the formulas derived from the model we established, we can obtain the signal interference ratio and further to calculate the amount of remaining subcarrier and the throughput of the system. Finally, through numerical calculation and simulation, the result shows that the load balancing and spectrum division schemes can remit the resource stress of the overloaded cell and improve the spectrum utilization in adjacent cells.     

Design of a three-stage ring-type voltage-controlled oscillator with a wide tuning range by controlling the current level in an embedded delay cell

This paper presents a new design for a three-stage voltage-controlled differential ring oscillator embedded with a delay cell for a wide tuning range from 59 MHz to 2.96 GHz by adjusting the current level in the delay cell. The ring oscillator consists of a voltage-to-current converter, coder circuit, three-stage ring with delay cells, and current monitoring circuit to extend the tuning range of the proposed voltage-controlled oscillator. Each functional block has been designed for a minimum power consumption using the TSMC 0.18 μm CMOS technology. We simulate the performances of the proposed voltage-controlled oscillator in terms of phase noise, power consumption, tuning range, and gain. Our simulation results show that the proposed oscillator has the linear frequency–voltage characteristics over a wide tuning range. At each tuning range (mode), the calculated phase noise of the proposed ring oscillator at each tuning range (mode) was −87, −85, −81, and −79 dBc/Hz at a 1 MHz offset from the center frequency. The DC power of the proposed voltage-controlled oscillator consumed 0.86–3 mW under a 1.8 V supply voltage.