Review of the Development of China's Mobile Broadband Networks

The year of 2014 saw the beginning of China's LTE,which marks that China has become one of the major engines for the global LTE development.China dazzled in the construction of LTE networks,subscribers,and industry chain.However,the policy formulated around TD-LTE also put China in predicament and brought it many challenges.With this article,we are going to put China's market for mobile broadband networks into perspective,focusing on the development of China's LTE market,challenges that encountered,and the research in this area in the years to come.Besides,in regards to the problems that already appeared,we will,from policy-making,industry-level,and technological points of view,offer our suggestions on how China should do to make this market robust.

A SCHEDULING ALGORITHM USING COMPENSATING ROUND ROBIN IN PACKET-SWTICHING BROADBAND NETWORKS

A new approximation of fair queuing called Compensating Hound Robin (CRR) is presented in this paper. The algorithm uses packet-by-packet scheduler with a compensating measure. It achieves good fairness in terms of throughput, requires only O( I) time complexity to process a packet, and is simple enough to be implemented in hardware. After the performances are analyzed, the fairness and packet loss rate of the algorithm are simulated. Simulation results show that the CRR can effectively isolate the effects of contending .sources.

SDN-Based Broadband Network for Cloud Services

Over-the-top services and cloud services have created great challenges for telecom operators. To better meet the requirements of cloud services, we propose a decoupled network architecture. Software-defined networking/network function virtualization （SDN/ NFV） will be vital in the construction of cloud-oriented broadband infrastructure, especially within data centers and for intercon nection between data centers. We also propose introducing SDN/NFV in the broadband access network in order to realize a virtu- alized residential gateway （VRG）. We discuss the deployment modes of VRG.

Powering Next-Generation Broadband Networks: ZTE's World-First Flexible, Configurable Router

16 September 2013, Shenzhen--ZTE today unveiled the world＇s first flexible, reconfigurable terabit router that allows customers to build the highest-performance broadband networks. The terabit router supports the deployment of multiple line cards with processing capabilities of 10 Gbps to 1 Tbps. It also supports the deployment of modules that can scale throughput from 200 Gbps to 18 Tbps. For easy installation in a range of environments, the router interfaces are flexible and the component design is loose-coupled. This allows customers to customize networks to their needs and promotes adaptability, consistency, and continuity.

ZTE Selected by BelTelecom for GPON National Broadband Network Project

ZTE Corporation announced on May 30, 2011 that it had won BelTelecom＇s national broadband network project in Belarus.

Evaluation of Rural Broadband Network Based on Broadband Universal Service Management System

Carrying out pilot project to provide broadband universal service nationwide, especially in rural impoverished areas, is a major policy decision in China. To accelerate implementation and ensure quality of the constructed network, it is of great significance to conduct comprehensive and scientific evaluation of the network status. In this paper, we present the evaluation of the broadband network constructed in rural China with several key indicators. It shows that with steppedup efforts of the telecom industry, broadband networks have been introduced into more and more villages. The average network speed reaches 60 Mbps, which is far exceeding 12 Mbps’ obligation.

回程网构建师 Cambridge Broadband Networks

对于全球无线通信市场而言,2008年是波澜壮阔、无比兴奋的一年。虽然金融风暴使全球经济增长放缓,但是通信领域的技术成长依然可圈可点。无线通信领域的技术进步目前极为迅速,成为引领整个信息通信产业发展的强大动力。各种无线技术"百舸争流":3G走向规模化商用;多种宽带无线技术迅速成熟;众多短距离无线技术长足发展;4G标准也全面启航……,众多初创企业也争相进入这一激烈的竞争当中。到底各种技术之间是互相竞争,还是互相补充,哪种无线技术将获得更好的市场发展空间?本刊将一连两期带您聚焦2008年无线通信领域的热门技术。

Mean Opinion Score Estimation for Mobile Broadband Networks Using Bayesian Networks

Mobile broadband(MBB)networks are expanding rapidly to deliver higher data speeds.The fifth-generation cellular network promises enhanced-MBB with high-speed data rates,low power connectivity,and ultralow latency video streaming.However,existing cellular networks are unable to perform well due to high latency and low bandwidth,which degrades the performance of various applications.As a result,monitoring and evaluation of the performance of these network-supported services is critical.Mobile network providers optimize and monitor their network performance to ensure the highest quality of service to their end-users.This paper proposes a Bayesian model to estimate the minimum opinion score(MOS)of video streaming services for any particular cellular network.The MOS is the most commonly used metric to assess the quality of experience.The proposed Bayesian model consists of several input data,namely,round-trip time,stalling load,and bite rates.It was examined and evaluated using several test data sizes with various performance metrics.Simulation results show the proposed Bayesian network achieved higher accuracy overall test data sizes than a neural network.The proposed Bayesian network obtained a remarkable overall accuracy of 90.36%and outperformed the neural network.

Evaluation of Broadband Network Performance in Nigeria

Broadband provides high speed data transmission to Internet and 4G networks were developed to transform broadband technology with higher data rate and enhanced quality of service. The performance of broadband network in Nigeria in terms of type, purpose and speed was evaluated in this work. Some quarters at Ilesa and Oba-Ile in Akure were chosen as rural areas, while Abuja and Lagos represented the urban areas of the study. Questionnaires were administered among users in these areas randomly. Thereafter, data were analyzed and research questions answered from the analyzed results. The results showed that the majority of the respondents operated on wireless broadband technologies. The download speed is generally above 100 mbps in urban areas and below in rural areas, with MTN having the highest number of subscribers. In addition, most of the Internet surfers download files. With these characteristics, it was discovered that the network operators were deploying 3G systems as broadband instead of 4G systems.

MOFs‑Derived Strategy and Ternary Alloys Regulation in Flower‑Like Magnetic‑Carbon Microspheres with Broadband Electromagnetic Wave Absorption

Broadband electromagnetic(EM)wave absorption materials play an important role in military stealth and health protection.Herein,metal–organic frameworks(MOFs)-derived magnetic-carbon CoNiM@C(M=Cu,Zn,Fe,Mn)microspheres are fabricated,which exhibit flower-like nano–microstructure with tunable EM response capacity.Based on the MOFs-derived CoNi@C microsphere,the adjacent third element is introduced into magnetic CoNi alloy to enhance EM wave absorption performance.In term of broadband absorption,the order of efficient absorption bandwidth(EAB)value is Mn>Fe=Zn>Cu in the CoNiM@C microspheres.Therefore,MOFs-derived flower-like CoNiMn@C microspheres hold outstanding broadband absorption and the EAB can reach up to 5.8 GHz(covering 12.2–18 GHz at 2.0 mm thickness).Besides,off-axis electron holography and computational simulations are applied to elucidate the inherent dielectric dissipation and magnetic loss.Rich heterointerfaces in CoNiMn@C promote the aggregation of the negative/positive charges at the contacting region,forming interfacial polarization.The graphitized carbon layer catalyzed by the magnetic CoNiMn core offered the electron mobility path,boosting the conductive loss.Equally importantly,magnetic coupling is observed in the CoNiMn@C to strengthen the magnetic responding behaviors.This study provides a new guide to build broadband EM absorption by regulating the ternary magnetic alloy.

Dielectric loss enhancement induced by the microstructure of CoFe_(2)O_(4) foam to realize broadband electromagnetic wave absorption

CoFe_(2)O_(4)has been widely used for electromagnetic wave absorption owing to its high Snoek limit,high anisotropy,and suitable saturation magnetization;however,its inherent shortcomings,including low dielectric loss,high density,and magnetic agglomeration,limit its application as an ideal absorbent.This study investigated a microstructure regulation strategy to mitigate the inherent disadvantages of pristine CoFe_(2)O_(4)synthesized via a sol–gel auto-combustion method.A series of CoFe_(2)O_(4)foams(S0.5,S1.0,and S1.5,corresponding to foams with citric acid(CA)-to-Fe(NO_(3))_(3)·9H_(2)O molar ratios of 0.5,1.0,and 1.5,respectively)with two-dimensional(2D)curved surfaces were obtained through the adjustment of CA-to-Fe^(3+)ratio,and the electromagnetic parameters were adjusted through morphology regulation.Owing to the appropriate impedance matching and conductance loss provided by moderate complex permittivity,the effective absorption bandwidth(EAB)of S0.5 was as high as 7.3 GHz,exceeding those of most CoFe_(2)O_(4)-based absorbents.Moreover,the EAB of S1.5 reached 5.0 GHz(8.9–13.9 GHz),covering most of the X band,owing to the intense polarization provided by lattice defects and the heterogeneous interface.The three-dimensional(3D)foam structure circumvented the high density and magnetic agglomeration issues of CoFe_(2)O_(4)nanoparticles,and the good conductivity of 2D curved surfaces could effectively elevate the complex permittivity to ameliorate the dielectric loss of pure CoFe_(2)O_(4).This study provides a novel idea for the theoretical design and practical production of lightweight and broadband pure ferrites.

Gradient carbonyl-iron/carbon-fiber reinforced composite metamaterial for ultra-broadband electromagnetic wave absorption by multi-scale integrated design

The demand of high-end electromagnetic wave absorbing materials puts forward higher requirements on comprehensive performances of small thickness,lightweight,broadband,and strong absorption.Herein,a novel multi-layer stepped metamaterial absorber with gradient electromagnetic properties is proposed.The complex permittivity and permeability of each layer are tailored via the proportion of carbonyliron and carbon-fiber dispersing into the epoxy resin.The proposed metamaterial is further optimized via adjusting the electromagnetic parameters and geometric sizes of each layer.Comparing with the four-layer composite with gradient electromagnetic properties which could only realize reflection loss(RL)of less than−6 dB in 2.0-40 GHz,the optimized stepped metamaterial with the same thickness and electromagnetic properties realizes less than−10 dB in the relevant frequency range.Additionally,the RL of less than−15 dB is achieved in the frequency range of 11.2-21.4 GHz and 28.5-40 GHz.The multiple electromagnetic wave absorption mechanism is discussed based on the experimental and simulation results,which is believed to be attributed to the synergy effect induced by multi-scale structures of the metamaterial.Therefore,combining multi-layer structures and periodic stepped structures into a novel gradient absorbing metamaterial would give new insights into designing microwave absorption devices for broadband electromagnetic protections.

Broadband high-efficiency dielectric metalenses based on quasi-continuous nanostrips

Benefiting from the abrupt phase changes within subwavelength thicknesses,metasurfaces have been widely applied for lightweight and compact optical systems.Simultaneous broadband and high-efficiency characteristics are highly attractive for the practical implementation of metasurfaces.However,current metasurface devices mostly adopt discrete micro/nano structures,which rarely realize both merits simultaneously.In this paper,dielectric metasurfaces composed of quasi-continuous nanostrips are proposed to overcome this limitation.Via quasi-continuous nanostrips metasurface,a normal focusing metalens and a superoscillatory lens overcoming the diffraction limit are designed and experimentally demonstrated.The quasi-continuous metadevices can operate in a broadband wavelength ranging from 450 nm to 1000nm and keep a high power efficiency.The average efficiency of the fabricated metalens reaches 54.24%,showing a significant improvement compared to the previously reported metalenses with the same thickness.The proposed methodology can be easily extended to design other metadevices with the advantages of broadband and high-efficiency in practical optical systems.

Ultralight pyrolytic carbon foam reinforced with amorphous carbon nanotubes for broadband electromagnetic absorption

For electromagnetic wave-absorbing materials,maximizing absorption at a specific frequency has been constantly achieved,but enhancing the absorption properties in the entire band remains a challenge.In this work,a 3D porous pyrolytic carbon(PyC)foam matrix was synthesized by a template method.Amorphous carbon nanotubes(CNTs)were then in-situ grown on the matrix surface to obtain ultralight CNTs/Py C foam.These in-situ grown amorphous CNTs were distributed uniformly and controlled by the catalytic growth time and can enhance the interface polarization and conduction loss of composites.When the electromagnetic wave enters the internal holes,the electromagnetic energy can be completely attenuated under the combined action of polarization,conductivity loss,and multiple reflections.The ultralight CNTs/Py C foam had a density of 22.0 mg·cm^(-3)and a reflection coefficient lower than-13.3 d B in the whole X-band(8.2-12.4 GHz),which is better than the conventional standard of effective absorption bandwidth(≤-10 dB).The results provide ideas for researching ultralight and strong electromagnetic wave absorbing materials in the X-band.

A flexible ultra-broadband multi-layered absorber working at 2 GHz-40 GHz printed by resistive ink

A flexible extra broadband metamaterial absorber(MMA)stacked with five layers working at 2 GHz–40 GHz is investigated.Each layer is composed of polyvinyl chloride(PVC),polyimide(PI),and a frequency selective surface(FSS),which is printed on PI using conductive ink.To investigate this absorber,both one-dimensional analogous circuit analysis and three-dimensional full-wave simulation based on a physical model are provided.Various crucial electromagnetic properties,such as absorption,effective impedance,complex permittivity and permeability,electric current distribution and magnetic field distribution at resonant peak points,are studied in detail.Analysis shows that the working frequency of this absorber covers entire S,C,X,Ku,K and Ka bands with a minimum thickness of 0.098λ_(max)(λ_(max) is the maximum wavelength in the absorption band),and the fractional bandwidth(FBW)reaches 181.1%.Moreover,the reflection coefficient is less than-10 dB at 1.998 GHz–40.056 GHz at normal incidence,and the absorptivity of the plane wave is greater than 80%when the incident angle is smaller than 50°.Furthermore,the proposed absorber is experimentally validated,and the experimental results show good agreement with the simulation results,which demonstrates the potential applicability of this absorber at 2 GHz–40 GHz.

Suppression of low-frequency ultrasound broadband vibration using star-shaped single-phase metamaterials

In order to suppress the low-frequency ultrasound vibration in the broadband range of 20 k Hz—100 k Hz,this paper proposes and discusses an acoustic metamaterial with low-frequency ultrasound vibration attenuation properties,which is configured by hybrid arc and sharp-angle convergent star-shaped lattices.The effect of the dispersion relation and the bandgap characteristic for the scatterers in star-shaped are simulated and analyzed.The target bandgap width is extended by optimizing the geometry parameters of arc and sharp-angle convergent lattices.The proposed metamaterial configured by optimized hybrid lattices exhibits remarkable broad bandgap characteristics by bandgap complementarity,and the simulation results verify a 99%vibration attenuation amplitude can be obtained in the frequency of20 k Hz—100 k Hz.After the fabrication of the proposed hybrid configurational star-shaped metamaterial by 3D printing technique,the transmission loss experiments are performed,and the experimental results indicate that the fabricated metamaterial has the characteristics of broadband vibration attenuation and an amplitude greater than 85%attenuation for the target frequency.These results demonstrate that the hybrid configurational star-shaped metamaterials can effectively widen the bandgap and realize high efficiency attenuation,which has capability for the vibration attenuation in the application of highprecise equipment.

Broadband Dual-Input Doherty Power Amplifier Design Based on a Simple Adaptive Power Dividing Ratio Function

In this paper,a simple adaptive power dividing function for the design of a dual-input Doherty power amplifier(DPA)is presented.In the presented approaches,the signal separation function(SSF)at different frequency points can be characterized by a polynomial.And in the practical test,the coefficients of SSF can be determined by measuring a small number of data points of input power.Same as other dualinput DPAs,the proposed approach can also achieve high output power and back-off efficiency in a broadband operation band by adjusting the power distribution ratio flexibly.Finally,a 1.5-2.5 GHz highefficiency dual-input Doherty power amplifier is implemented according to this approach.The test results show that the peak power is 48.6-49.7d Bm,and the 6-d B back-off efficiency is 51.0-67.0%,and the saturation efficiency is 52.4-74.6%.The digital predistortion correction is carried out at the frequency points of 1.8/2.1GHz,and the adjacent channel power ratio is lower than-54.5d Bc.Simulation and experiment results can verify the effectiveness and correctness of the proposed method.

Highly Efficient Broadband Achromatic Microlens Design Based on Low-Dispersion Materials

Metalenses with achromatic performance offer a new opportunity for high-quality imaging with an ultracompact configuration;however,they suffer from complex fabrication processes and low focusing efficiency.In this study,we propose an efficient design method for achromatic microlenses on a wavelength scale using materials with low dispersion,an adequately designed convex surface,and a thickness profile distribution.By taking into account the absolute chromatic aberration,relative focal length shift(FLS),and numerical aperture(NA),microlens with a certain focal length can be realized through our realized map of geometric features.Accordingly,the designed achromatic microlenses with low-dispersion fused silica were fabricated using a focused ion beam,and precise surface profiles were obtained.The fabricated microlenses exhibited a high average focusing efficiency of 65%at visible wavelengths of 410-680 nm and excellent achromatic capability via white light imaging.Moreover,the design exhibited the advantages of being polarization-insensitive and near-diffraction-limited.These results demonstrate the effectiveness of our proposed achromatic microlens design approach,which expands the prospects of miniaturized optics such as virtual and augmented reality,ultracompact microscopes,and biological endoscopy.

A new adaptive co-site broadband interference cancellation method with auxiliary channel

With the boom of the communication systems on some independent platforms(such as satellites,space stations,airplanes,and vessels),co-site interference is becoming prominent.The adaptive interference cancellation method has been adopted to solve the co-site interference problem.But the broadband interference cancellation performance of traditional Adaptive Co-site Interference Cancellation System(ACICS)with large delay mismatching and antenna sway is relatively poor.This study put forward an Adaptive Co-site Broadband Interference Cancellation System With Two Auxiliary Channels(ACBICS-2A).The system model was established,and the steady state weights and Interference Cancellation Ratio(ICR)were deduced by solving a time-varying differential equation.The relationship of ICR,system gain,modulation factor,interference signal bandwidth and delay mismatching degree was acquired through an in-depth analysis.Compared with traditional adaptive interference cancellation system,the proposed ACBICS-2A can improve broadband interference cancellation ability remarkably with large delay mismatching and antenna sway for the effect of auxiliary channel.The maximum improved ICR is more than 25 dB.Finally,the theoretical and simulation results were verified by experiments.