Status and Trends of Satellite-to-earth Optical Communications

The development ofinformation society needs a communications system with high data transmission rate, large storage capacity, and wide coverage as support. Facing the increasing demands on the satellite communications capacity and the data transmissions rate, communication technologies based on microwave cannot yet meet the demands. Therefore, new communications media and technologies need to be urgently found. With the breakthough ofkey technologies in satellite laser communications and the g…     

Research and Development of New Broadband Wireless Access System

Broadband Wireless Access (BWA) has become one of the major evolution trends in the fields of broadband access and mobile communications. However,some difficulties emerged during the application and industrialization of the BWA system,which calls for typical service models,key technology innovations and backbone support from broadband Internet. This article introduces a Broadband Wireless Multimedia (BWM) access system. It aims to build a new-type "triple play" BWA network by integrating terrestrial digital TV system and the BWA system,and by taking broadband Internet as its core network platform. A primary research shows that the new BWA system is an effective solution to the existing difficulties of BWA system. Moreover,it is quite competitive in service provision,service coverage,frequency planning,terminal power consumption and cost for network construction.     

Wireless Mesh Architecture for IP-Based Base Stations

Combining the performance advantages of both Wireless Local Area Network (WLAN) and Ad hoc network, Wireless Mesh Network (WMN) is characterized by large capacity, high rate and wide coverage. It has become an effective means for broadband wireless access and can be applied flexibly in various wireless environments. The wired connections between base stations in traditional cellular mobile communications systems can no longer satisfy the requirements for flexible deployment, low cost, high scalability and good reliability. The wireless Mesh architecture for IP-based base stations is thus introduced as an optional solution to support the flat and simplified next generation mobile communications networks. The key technologies used to support self-organization of IP-based base stations involve several aspects, including on-demand self-organization of base stations, joint radio resource scheduling mechanism, routing, security and network management.     

Inter-domain traffic balancing with co-channel interference management in multi-domain heterogeneous network for LTE-A

Heterogeneous network(Het-Net) is part of the long-term evolution advanced(LTE-A) study item and represents cellular deployments with a mixture of cells of different overlapping coverage areas,e.g.,a number of relay and pico cells overlaid by a macro cell in the same frequency.Traffic balancing and interference management are required in Het-Net design for LTE-A to maintain system performance.In this paper,we propose an inter-domain cooperative traffic balancing scheme focusing on reducing the effective resource cost and mitigating the co-channel interference in multi-domain Het-Net.We first set up the conception of multi-domain in Het-Net and incorporate the co-channel interference into the proposed traffic balancing scheme.Then we model the traffic balancing issue as a multi-domain traffic resource optimization problem for minimizing the effective resource cost.The detailed implementation for the proposed traffic balancing scheme is designed.In the numerical evaluation,the genetic algorithm(GA) as an optimization method is used to demonstrate that the total effective resource cost is significantly reduced through our proposed inter-domain traffic balancing scheme,comparing with the intra-domain traffic balancing scheme.The 43% of the resource cost is saved.In the system level simulation,the performance results of signal interference noise ratio(SINR) and throughput demonstrate that the proposed scheme has great advantages in interference management in Het-Net.     

Distance control strategy for deploying content replica servers in an edge cloud

To reduce fetching cost from a remote source,it is natural to cache information near the users who may access the information later.However,with development of 5 G ultra-dense cellular networks andmobile edge computing(MEC),a reasonable selection among edge servers for content delivery becomes a problem when the mobile edge obtaining sufficient replica servers.In order to minimize the total cost accounting for both caching and fetching process,we study the optimal resource allocation for the content replica servers’ deployment.We decompose the total cost as the superposition of cost in several coverages.Particularly,we consider the criterion for determining the coverage of a replica server and formulate the coverage as a tradeoff between caching cost and fetching cost.According to the criterion,a coverage isolation(CI) algorithm is proposed to solve the deployment problem.The numerical results show that the proposed CI algorithm can reduce the cost and obtain a higher tolerance for different centrality indices.     

A Dormant Multi-Controller Model for Software Defined Networking

In order to improve the scalability and reliability of Software Defined Networking （SDN）, many studies use multiple controllers to constitute logically centralized control plane to provide load balancing and fail over. In this paper, we develop a flexible dormant multi-controller model based on the centralized multi-controller architecture. The dormant multi-controller model allows part of controllers to enter the dormant state under light traffic condition for saving system cost. Meanwhile, through queueing analysis, various performance measures of the system can be obtained. Moreover, we analyze the real traffic of China Education Network and use the results as the parameters of computer simulation and verify the effects of parameters on the system characteristics. Finally, a total expected cost function is established, and genetic algorithm is employed to find the optimal values of various parameters to minimize system cost for the deployment decision making.     

Status Quo and Prospect of Millimeter Wave RoF Communication Technology

The optical communication technology features low cost,wide band,low loss,and anti-electromagnetic interference performance.By combining the optical communication technology with the radio millimeter wave communication system,the Millimeter Wave Radio over Fiber (MM-RoF) system boasts a lot of advantages,including wide band,small size,light weight,low cost,low loss,and resistance of electromagnetic interference as well as high transmission quality.The MM-RoF technology solves the problems faced by traditional microwave transmission system at the millimeter wave band,namely,high loss and inability to resist interference efficiently.Meanwhile,it puts an end to the bottleneck of millimeter wave electronic devices and thus is deemed as with great potentials.The MM-ROF technology that supports multiple formats and services signifies one of the significant trends for future development of the MM-RoF system.     

On UAV Serving Node Deployment for Temporary Coverage in Forest Environment:A Hierarchical Deep Reinforcement Learning Approach

Unmanned aerial vehicles(UAVs) can be effectively used as serving stations in emergency communications because of their free movements, strong flexibility, and dynamic coverage. In this paper, we propose a coordinated multiple points based UAV deployment framework to improve system average ergodic rate, by using the fuzzy C-means algorithm to cluster the ground users and considering exclusive forest channel models for the two cases, i.e., associated with a broken base station or an available bas...     

Coverage and capacity optimization in LTE network based on non-cooperative games

As to provide the optimal coverage and capacity performance,support high-data-rate service and decrease the capital expenditures and operational expenditures(OPEX)(CAPEX) for operator,the coverage and capacity optimization(CCO) is one of the key use cases in long term evolution(LTE) self-organization network(SON).In LTE system,some factors(e.g.load,traffic type,user distribution,uplink power setting,inter-cell interference,etc.) limit the coverage and capacity performance.From the view of single cell,it always pursuits maximize performance of coverage and capacity by optimizing the uplink power setting and intra-cell resource allocation,but it may result in decreasing the performance of its neighbor cells.Therefore,the benefit of every cell conflicts each other.In order to tradeoff the benefit of every cell and maximize the performance of the whole network,this paper proposes a multi-cell uplink power allocation scheme based on non-cooperative games.The scheme aims to make the performance of coverage and capacity balanced by the negotiation of the uplink power parameters among multi-cells.So the performance of every cell can reach the Nash equilibrium,making it feasible to reduce the inter-cell interference by setting an appropriate uplink power parameter.Finally,the simulation result shows the proposed algorithm can effectively enhance the performance of coverage and capacity in LTE network.     

Research on uplink coordinated transmission schemes in LTE-advanced systems

The investigation of inter-cell interference mitigation techniques is a key area in wireless communications.Coordinated multiple points(CoMP) transmission/reception is a candidate technique for interference cancellation in 3GPP LTE-Advanced system.However,the coordination scheme in CoMP remains a key research problem to be solved,which will have a strong influence on the performance of CoMP.In this paper,a novel coordinated transmission scheme is proposed for the uplink LTE-Advanced system.In our scheme,several base transceiver stations(BTS) and users are selected as coordination partners which form a CoMP cluster.Joint processing is used at the receiver to mitigate interference.From the perspective of coordinated partner selection,our scheme can be divided into static and dynamic coordination which are both considered to fully exploit the throughput gain of CoMP.The proposed schemes are evaluated by system level simulation and compared with the conventional LTE system based upon single cell processing.Our simulation results demonstrate that the proposed schemes attain superior performance as opposed to the conventional system in terms of cell average and cell edge throughput.     

Integrated RF architectures in fully-organic SOP technology

Future wireless communications systems require better performance, lower cost, and compact RF front-end footprint. The RF front-end module development and its level of integration are, thus, continuous challenges. In most of the presently used microwave integrated circuit technologies, it is difficult to integrate the passives efficiently with required quality. Another critical obstacle in the design of passive components, which occupy the highest percentage of integrated circuit and circuit board real estate, includes the effort to reduce the module size. These issues can be addressed with multilayer substrate technology. A multilayer organic (MLO)-based process offers the potential as the next generation technology of choice for electronic packaging. It uses a cost effective process, while offering design flexibility and optimized integration due to its multilayer topology. We present the design, model, and measurement data of RF-microwave multilayer transitions and integrated passives implemented in a MLO system on package (SOP) technology. Compact, high Q inductors, and embedded filter designs for wireless module applications are demonstrated for the first time in this technology.     

Universal Digital Portable Communications: A System Perspective

In our highly mobile society, the provision of voice and data communications to a person away from his/her wireline telephone has become a major communications frontier. The early penetration of this frontier has been based on very limited portable communications approaches, e.g., cordless telephones, mobile radio telephones, and radio paging. Each of these approaches only partially satisfies portable communications needs. This paper describes an approach to providing universal digital portable communications integrated into telephone networks. A system configuration employing time-division multiple-access radio link architecture and frequency reuse is described. Issues affecting radio link transmission rates and radio system coverage are discussed. Characteristics and parameters of a possible system to supplement the wire (or fiber) loop are indicated.     

A high-efficiency broadband HF wire-antenna system

The purpose of this antenna design is to provide an efficient, broadband, wire-antenna system for RF communications. The benefits of the antenna include a single integrated antenna system for total band coverage, high system efficiency across the operating band, the capability to transmit and receive multiple signals instantaneously, and simple mechanical assemblies. The antenna design comprises various configurations of multiple transceivers, connected to a set of RF filters and associated impedance-matching networks, which are used to excite a plurality of trapped-antenna elements. The antenna system offers control over the antenna's directivity and the antenna's driving-point impedance by using sub-band systems, as defined by a series of RF filters and traps that divide the physical antenna element into varying radiating lengths. Continuous coverage over the entire frequency band of interest is achieved by using different physical antenna elements for adjacent sub-bands. The utilization of sub-bands reduces the impedance-matching network requirements, and helps to more efficiently radiate energy over the entire frequency band of interest. The resultant higher antenna system efficiencies allow for moderate and feasible performance specifications for transmitters, receivers, and matching-network components. The design can utilize various configurations and orientations of monopoles, dipoles, associated arrays, and RF traps     

A satellite‐augmented cellular network concept

Some next‐generation personal communication systems propose the use of satellite systems for extending geographical coverage of cellular service. We pursue the idea of using satellite capacity to offload congestion within the area serviced by the terrestrial network. An integrated satellite‐cellular network configuration is considered. The performance of this system is evaluated by means of an analytical model for a one‐dimensional (highway) cellular system overlaid with satellite footprints and by means of simulation for a planar cellular network with satellite spot beam support. Under certain re‐use assumptions, an improvement is found in the blocking performance of the integrated system over the Erlang‐B blocking of a purely cellular circuit switched systems. This is achieved by efficient partitioning (static) of the total bandwidth into space and terrestrial segments. Major factors that influence performance, such as different reuse considerations on the satellite and cellular systems, cell size to footprint size ratios, admission control and call management policies, and changes in traffic patterns, are also investigated. This revised version was published online in June 2006 with corrections to the Cover Date.     

Global communications in the information age

Advances in application-specific integrated circuits (ASICs) are steadily moving global communications toward its ultimate goal: to secure voice, data and images in any combination, anywhere, at any time. Current trends in ASIC design that are leading to more reliable circuits which offer increasing performance at lower and lower cost per function are discussed. The trends include finer features, increasing complexity, shorter design cycles, and the use of more powerful simulation and CAD tools all of which lead to an increasingly pervasive use of integrated circuits     

A multimedia interhospital communications system for medicalconsultations

The authors present a study whose main objective has been to explore the use of high-bandwidth multimedia communications technology for medical applications physically distributed among hospitals, that is to say an interhospital multimedia communications system. The design and development issues of a prototype are described, as well as the results of an in-field trial. From the results of this trial, a performance study has been developed for evaluating the expected communications requirements of a large-scale configuration of the system     

基于MCGS数字温度传感器的温度巡检系统设计

针对储煤场实际情况设计的温度巡检系统抛弃传统采温传感器,采用新型三端数字传感器,监控系统采用组态软件MCGS,大大减少系统硬件设计、软件开发量,提高系统反映敏感度.详细叙述硬件配置、系统控制过程,介绍使用MCGS开发的系统界面、温度采集程序.系统已运行两年,实践证明系统整体性价比极佳,已在一些仓库推广.     

地面空中接口在卫星移动通信的适用性研究

为发展星地一体化网络、真正实现全球无缝覆盖,研究地面移动通信空中接口在卫星通信的适用性是一种有效的解决思路。本文系统性的介绍了地面3G/4G移动通信空中接口和卫星通信系统架构,总结了现有文献关于地面空中接口在星上的适用性初步评估,对比分析了各种地面空中接口在卫星信道环境下的链路性能,为地面空中接口在星上应用的改进方向提供了参考依据。     

Application of adaptive array antenna to a TDMA cellular/PCS system

This article discusses the use of an adaptive array antenna technology in a TDMA cellular/personal communications services (PCS) system and demonstrates that the adaptive array antenna improves cell coverage, provides better signal quality, and reduces cost of deployment of cellular/PCS service in a given area